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HomeMy WebLinkAboutSusitna FERC exhibit B 1982D=U&OO~& c ~riD~~®©© Susitna Joint Venture Document Number {(a3 Please Return To DOCUMENT CONTROL I l I I I I I I I I : I I t Pre·pared by: IJ~Im ---·------------_.__.~~---------------, SUSITNA HYDROELECTRIC PROJEC:T DRAFT FERC LICENSE APPLICAT!ON EXHIBIT B PROJECT OPERATION AND RESOURCE UTILIZATION NOVEMBER 1982 I I I I I I . I I i I I I I I 1 I ! ...___ __ ALfl\SKA POWER AUTHORITY---=.;.- rr·--------~ Prepared by: SUSITNA HYDROELECTRIC PROJECT DRAFT FERC LICENSE APPLICATION EXHISIT 8 PROJECT OPERATION AND RESOURCE UTILIZATION NOVEMBER 1982 L..._. __ ALASKA POWER AU-rHORJTY~,-----~ • ' .. ; . \ .. · , ' . .. ' f· • • • • '. • . . ' ' .. , . . . . I EXHIBIT B -STATEMENT OF PROJECT OPERATION AND RESOURCE UTILIZATION List of Tables List of Figures 1 -DAMSITE SELECTION ........................ , ...... ~ ........... . 1.1 -Previous Studies ..................................... . (a) Early Studies of Hydroelectric Potential ........ . (b) U.S. Bureau of Reclamation-1953 Study ......... . (c) U.S. Bureau of Reclamation-1961 Study ......... . (d) Alaska Power Administration-1974 Study ........ . (e) Kaiser Proposal for Development ................. . (f) U.S. Army Corps Engineers -1975 and 1979 Studies. 1.2-Plan Formulation and Selection Methodology···~········ 1.3-Damsite Selection .................................... . (a) Site Screening .................................. . (b) Engineering Layouts ............................. . (CJ Capital Costs ..•........................•......•. 1.4-Formulation of Susitna Basin Development Plans .•...... (a) Tunnel Alternatives .....................•........ (b) Se 1 eeted Basin Oeve 1 opment Plans ................ . (c) Selected Basin Development Plans ·····~··········· 1.5-Evaluation of Basin Development Plans ................ . (a) Evaluation Methodology .......................... . (b) Evaluation Criteria ...........•.................. (c) Results of Evaluation Process ..............•..... 1.6-Preferred Susitna Basin Development Plan ............. . 2-ALTERNATIVE FACILITY DESIGN, PROCESSES AND OPERATIONS ...... . 2.1-Susitna Hydroelectric Development .................... . 2.2-Watana Project Form•Jlation ·········H···········o····· (a) Selection of Reservoir Level ·····~· .. ~············ (b) Selection of Installed Capacity ......•........... (c) Selection of Spillway Design Floods v••··········· (d) Main Dam Alternatives ...... " .......... , ....... ,.~ (e) Diversion Scheme Alternatives ········~··········· (f) Spillway Facilities Alternatives ................ . (g) Power Facilities Alternatives .................... . 2.3-Selection of Watana General Arrangement ....... .,~······ (a) Selection Methodology····~····~·················· (b) Design Data and Criteria ...............•......... (c) Evaluation Criteria ............................. . (d) Pre 1 imi nary Review .............................. . (e) Intermediate Review ............................. . (f) Fin a 1 Rev i ew .................................... . 2.4 -Devil Canyon Project Formulation ..................... . (a) Selection of Reservoir Level .................... . (b) Selection of Installed Capacity ................. . (c) Selection of Spillway Capacity .................. . (d) Main Dam Alternatives ........................... . (e) Diversion Scheme Alternatives ................... . (f) Spillway Alternatives ........................... . (g) Power Facilities Alternatives ..... , ............. . PagE 1-1 1-1 1-1 1-2 1-2 1-3 1-3 1-3 1-4 1-5 1-6 1-7 1-11 1-11 1-13 1-14 1-14 1-16 1-16 1-21 1-22 1-25 2-1 2-1 2-1 2-2 2-5 2-7 2-8 2-13 2-17 2-18 2-22 2~22 2-24 2-24 2-24 2-30 2-35 2-41 2-42 2"'"42 2-43 2-44 2~48 2-50 2-51 • ' ' .. .. .J • j . . . ··-~!:~~~,.~~~---~-----~------····---·--·--·~ ·-----------· ______ ..:._ ____ :;z _____ ~...:.~---------.·_ -~ ......... ::....... ______ _y_.....L.... __ .:..::_..;,.."--.:...,___~----..;::..........o.;; .. __ ~_~---~--·.~ ·i·-~-- p • J Table of Contents (Continued) . 2.5-Selection of Devil Canyon General Arrangement ........ . (a) Selection Methodology ................•........... {b) Design Data Criteria ................•............ (c) Preliminary Review .............................. . (d) Final Review .................................... . 2,6-Selection of Access Road Corridor .................... . (a) Previous Studies .........•....................... (b) Selection Process Constraints ................... . (c) Corridor Identification and Selection ..•......•.. (d) Development of Plans ............................ . (e) Evaluation of Plans ............................. . (f) Comparison of the Selected Alternative Plans .... . (g) Summary ...........••..............•.............. (h) Final Selection of Plan ..•.......•............... 2,.7 -Selection of Transmission Facilities ................. . Page 2-53 2-53 2-53 2-53 2-58 2-59 2-59 2-60 2-60 2-61 2-61 2-64 2-72 2-72 2-75 (a) Electric System Studies ..........•............... {b) Corridor Selection .....................•......... (c) Corridor ~reening ..................•...•.•...... 2-75 2-82 2-93 2-102 2-106 2-112 2-118 2-119 2-119 2-119 2-119 2-120 2-120 2-120 2-121 3-1 3-1 3-2 3-2 3-2 3-2 3-3 3-3 3-4 3-4 3-5 3-6 3-6 3-6 3-6 3-7 3-7 3-8 (d) Recommended Corridors ........................... . (e) Route Selection ................................. . (f) Towers, Foundations and Conductors .............. . 2. 8 -Selection of Project Operation ....................... . (a) Pre-Project Flows ........................•....... (b) Range of Post-Project Flows .................... .. (c) Timing of Flow Releases ....•.........•.....•...•. (d) Maximum Drawdown ................................ . (e) Ener~ Production ............................... . (f) Net Benefits ..•............................•..... (g) Operational Flow Scenario Selection ............. . (h) Instream Flow and Fishery Impact on Flow Selection .................................. . 3 -DESCRIPTION OF PROJECT OPERATION .......................... .. 3.1-Operation within Railbelt Power System ............... . 3.2-Plant and System Operation Requirements .............. . 3.3-General Power Plant and System Railbelt Criteria ..... . (a) Installed Generating Capacity .................. .. (b) Transmission System Capability .................. . (c) Summary .............•........•................... 3.4 -Economic Operation of Units ......................... .. (a) Merit-Order Schedule ............................ . {b) Optimum Load Dispatching ........................ . (c) Operating Limits of Units ....••...•.....•........ (d) Optimum Maintenance Program .................... .. 3.5 -Unit Operation Reliability Criteria ................. .. (a) Power System Analyses ....•..••................... (b) System Response and Load-Frequency Centro l ...... . (c) Protective Relaying System and Devices .......... . 3.6-Dispatch Control Centers ....................•......... 3.7-Susitna Project Operation ............................ . J, ., .. l 1 I I I I Table of Contents (Continued) Page 4-ENERGY PRODUCTION AND SUPPORTING DATA ············•·o·····e·· 4-1 4.1-Hydrology ··································••o•······· 4-1 (a) Historical Streamflow Data ....................... 4-1 (b) Water Resources .................................. 4-1 (c) Streamflow Extension ········~···················· 4-2 (d) Critical Streamflow Used for Dependable Capacity .. 4-2 (e) Floods .........................................•. 4-2 (f) Flow Adjustments ................................. 4-3 4.2-Reservoir Data ........................................ 4-4 (a) Reservoir Storage ....•..•........................ 4-4 (b) Rule Curves ............................. 0 •••••••• 4-5 4.3-Operating Capabilities of Susitna Units .......•.•..... 4-5 ( a) ~~at an a . o • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 4-5 (b) Devil Canyon ................................. 0 •••• 4-6 4o4-Tailwater Rating Curve ························••oo•o•• 4-7 5-STATEMENT OF POWER NEEDS AND UTILIZATION .................... 5-1 5.1-Railbelt Load Forecasts ............................... 5-1 (a) Scope of Studies ................................. 5-1 (b) Electricity Demand Profiles ...................... 5-1 (c) Battelle Load Forecasts .......................... 5-5 5.2-Marketing and Price for Watana Output in 1994 ......... 5-10 (a) Contractual Preconditions for Susitna Energy Sale ........................................... 5-11 (b) Market Price for Watana Output 1995-2001 ...... 0 •• 5-12 (c) Market Price for Watana and Devil Canyon Output in 2003 ........................................ 5-12 (d) Potential Impact of State Appropriations ......... 5-12 (e) Conclusions ...................................... 5-12 5.3-Sale of Power ......................................... 5-12 6 -FUTURE SUSITNA BASIN DEVELOPMENT REFERENCES • • • • • • • • • • • • • ~ • • • • • 0 • • • • • • ~ ~ 6-1 L l L f I I I I I I I ,, -~ ~ ---·~..,..,._:.._....._,:,_~,_..._,._~~--" ,_, _____ ..,..,. .... ,_,....,.,_,, ..• _ ''-• _,_,__ -~-~--. ----.-~ . .-..---·----.,.,...--·~---~ _,,.._ -~--. _ _,, Exhibit B-Statement of Project Operation and Resource Utilization LIST OF TABLES Number B.l B.2 8.3 8.4 8.5 B.6 B.7 B.B 8.9 B.10 B.11 B.l2 B.13 B.14 8.15 8.16 B.17 8.18 B.l9 B.20 8.21 8.22 8.23 B.24 8.25 B.26 8.27 8.28 8.29 Title Potential Hydroelectric Development Cost Comparisons Dam Crest and Full Supply Levels Capital Cost Estimate Summaries -Susitna Basin Dam Schemes -Cost in$ Million 1980 Results of Screening Model Information on the Devil Canyon Dam and Tunnel Schemes Tunnel Schemes Power Output and Average Annual Energy Capital Cost Estimate Summaries for Scheme 3 Tunnel Alternative Costs in $ Million 1980 Susitna Development Plans Susitna Environmental Development Plans Results of Economic Analyses of Susitna Plans Results of Economic Analyses of Susitna Plans - Low and High Load Forecast Annual Fixed Carrying Charges Summary of Thermal Generating Resource Plant Parameters Economic Backup Data for Evaluation of Plans Economic Evaluation of Devil Canyon Dam and Tunnel Schemes and Watana/Devil Canyon and High Devil Canyon/Vee Plans Environmental Evaluation of Devil Canyon Dam and Tunnel Schemes Social Evaluation of Susitna Basin Development Schemes/Plans Energy Contribution Evaluation of the Devil Canyon Dam and Tunnel Schemes Overall Evaluation of Tunnel Scheme and Devil Canyon Dam Scheme Environmental Evaluation of Watana/Devil Canyon and High Devil Canyon/Vee Development Plans Energy Contribution Evaluation of the Watana/Devil Canycn and High Devil Canyon/Vee Plans Overall Evaluation of the High Devil Canyon/Vee and Watana/Devil Canyon Dam Plans Combined Watana and Devil Canyon Operation Present Worth of Production Costs Design Parameters for Dependable Capacity and Energy Production Watana -Maximum Capacity Required (MW) -Thermal as Base Watana -Maximum Capacity Required (MW) -Thermal as Peak Design Data and Design Criteria for Final Review of Layouts f 1 i LIST OF TABLES (Continued) Number Title 8.30 8.31 8.32 8.33 8.34 8.35 8.36 8 .. 37 8.38 8.39 8.40 8.41 8.42 8.43 8.44 8.45 8.46 8.47 8.48 8.49 8.50 8.51 8.52 8.53 8.54 8.55 8.56 8.57 8.58 8.59 8.60 Eva 1 uation Criteria Summary of Comparative Cost Estimates Devil Canyon -Maximum Capacity Required (MW) Design Data and Design Criteria for Review of Alteinative Layouts Summary of Comparative Cost Estimates Power Transfer Requirements (MW) Summary of Life Cycle Costs Technical, Economic, and Environmental Criteria Used in Corridor Selection En vi ronmenta 1 Inventory -Southern Study Area Environmental Inventory -Central Study Area Environmental Inventory -Northern Study Area Soil Associations Within the Proposed Transmission Corridors -General Description, OffrJad Trafficability, Limitations (ORTL), and Common Crop Suitability (CCS) Definitions for Offroad Trafficabflity Limitations and Common Crop Suitability of Soil Associations Economical and Technical Screening -Southern Study Area Economical and Technical Screening -Central Study Area Economical and Technical Screening -Northern Study Area Summary of Screening Results Environmental Constra·i nts -Southern Study Area Environmental Constraints -Central Study Area Environmental Constraints -Northern Study Area Technical Economic and Environmental Criteria Used in Corridor Screening Watana Estimated Natural Flows Devil Canyon Estimated Natural Flows Monthly Flow Requirements at Gold Creek Energy Potential of Watana -Devil Canyon Developments for Different Reservoir Operating Rules Net Benefits for Susitna Hydroelectric Project Operating Scenarios Average Annual and Monthly Flow at Gage in the Susitna Basin Peak Flows of Record Estimated Flow Peaks in Susitna River Flood Routing-Maximum Flows (cfs) Estimated Evaporation Losses -Watana and Devil Canyon Reservoirs L L L ! 1 t t l l l l I I I I I LIST OF TABLES (Continued) Number 8.61 8.62 8.63 8.64 8.65 8.66 8.67 8.68 8.69 8.70 8 .. 71 8.72 Minimum Releases at Watana Minimum Releases at Devil Canyon Water Appropriations Within One Mile of the Susitna River Turbine Operating Conditions Historical Annual Growth Rates of Electric Utility Sales Annual Growth Rates in Utility Customers and Consumption Per Customer Utility Sales by Railbelt Regions Summary of Railbelt Electricity Projections Forecast Total Generation and Peak Loads -Total Railbelt Region ISER 1980 Rail be 1 t Region Load and Energy Foree asts Used for Generation Planning Studies for Development Selection December 1981 Battelle PNL Railbelt Region Load and Energy Forecasts Used for Generation Planning Studies Battelle Demand Forecasts -Total Railbelt L t t l l L l l 1 I I I I Exhibit 8 -Statement of Project Operation and Resource Utilization LIST OF FIGURES Number 8.1 8.2 8.3 8.4 8.5 8.6 8.7 8.8 8.9 8.10 8.11 8.12 8.13 8.14 8.15 8.16 8.17 8.18 8.19 8.20 8.21 8.22 8.23 8.24 8.25 8.26 8.27 8.28 8.29 8.30 8.31 8.32 8.33 8.34 8.35 8.36 8.37 8.38 Title Location Map Damsites Proposed by Others Susitna Basin Plan Formulation and Selection Process Profile Through Alternative Sites Mutually Exclusive Development Alternatives Devil Canyon Hydro Development Fill Dam Watana Hydro Development Fill Dam Watana Staged Fill Dam High Devil Canyon Hydro Development Susitna III Hydro Development Vee Hydro Development Denali and Maclaren Hydro Developments Schematic Representation of Conceptual Tunnel Schemes Preferred Tunnel Scheme 3 Plan Views Preferred Tunnel Scheme 3 Sections Generation Scenario with Susitna Plan El.3 Generation Scenario with Susitna Plan E2.3 Generation Scenario with Susitna Plan E3.1 Watana Reservoir -Dam Crest Elevation/Present Worth of Product Costs Watana -Arch Dam Alternatives Watana -Alternative Dam Axes Watana Diversion -Headwater Elevation/Tunnel Diameter Watana Diversion -Upstream Cofferdam Costs Watana Diversion -Tunnel and Cofferdam Cost/Tunnel Diameter Watana Diversion -Total Cost/Tunnel Diameter Watana -Preliminary Schemes Watana-Scheme WP1 -Plan Watana -Scheme WP3 -Sections Watana -Scheme WP2 and WP 3 Watana -Scheme WP2 -Sections Watana-Scheme WP4-Plan Watana -Scheme WP4 -Sections Watana -Scheme WP3A Watana -Scheme WP4A Devil Canyon Diversion -Headwater Elevation Tunnel Diameter Devil Canyon Diversion -Total Cost Tunnel Diameter Devil Canyon -Scheme DC1 Devil Canyon -Scheme DC2 I· ' ~ L L l l I. I I I I I LIST OF FIGURES (Continued) Number Title 8.39 8.40 8.41 8.42 8.43 8.44 8.45 8.46 8.47 8.48 Be49 8.50 8.51 8.52 8.53 8.54 8.55 8.56 8.57 8.58 8.59 8.60 8.61 8.62 8.63 B.64 8.65 8.66 8.67 8.68 Devil Canyon -Scheme DC3 Devil Canyon -Scheme DC4 Devil Canyon -Selected Scheme Alternative Access Corridors Access Plan 13 (North) Access Plan 16 (South) Access Plan 18 (Proposed) Schedule for Access and Diversion Alternative Transmission Line Corridors - Southern Study Area Alternative Transmission Line Corridors - Central Study Area Alternative Transmission Line Corridors- Northern Study Area Recommended Transmission Line Corridor - Southern Study Area Recommended Transmission Line Corridor- Southern Study Area Recommended Transmission Line Corridor- Central Study Area Recommended Transmission Line Corridor- Central Study Area Recommended Transmission Line Corridor - Northe~n Study Area Recommended Transmission Line Corridor - Northern Study Area Recommended Transmission Line Corridor - Northern Study Area Recommended Transmission Line Corridor- Northern Study Area Typical Load Variation in Alaska Railbelt System Data Collection Stations Average Annut~.l Flow Distribution Within the Susitna River Basin Monthly Average Flows in the Susitna River at Gold Creek Flow Duration Curve Mean Monthly Inflow at Watana Pre-Project Flow Duration Curve Mean Monthly Inflow at Devil Canyon Pre-Project Frequency Analysis of Average Annual Energy for Susitna Developments Hydrological Data -Sheet 2 Hydrological Data -Sheet 2 Hydrological Data -Sheet 1 Hydrological Data -Sheet 1 l l l I I. !I, • LIST OF FIGURES (Continued} Number 8.69 8 • .70 8 . .71 8 .. .72 8 . .73 8.74 8 . .75 fL76 8.77 8.78 8.79 8.80 8.81 8.82 8.83 Title ~1onthly Tar9et Minimum Reservoir Levels Watana -Unit Output Watana -Turbine Performance (at Rated Head} Watana -Unit Efficiency (at Rated Head) Devil Canyon -Unit Output Devil Canyon -Turbine Performance (at Rated Head) Devil Canyon -Unit Efficiency (at Rated Head) Railbelt Area of Alaska Showing Electrical Load Centers Historical Total Railbelt Utility Sales to Final Customers ISER 1980 Energy Forecasts Used for Deve 1 opment Selection Studies Electric Power Forecasting Process December 1981. Battell.~ Load and Energy Forecasts Used for G~neration Planning Studies Energy Pricing Comparisons -1994 System Costs Avoided by Developing Susitna Energy Pricing Comparisons -2003 l t l I l l l l I . (l ,_.,,. ~--~------"........_"'""" .-~----~····-·-···--· ... __ ~-· ~ ;...-') 1 -DAMSITE SELECTION .. .. l l I I" EXHIBIT B -PROJECT OPERATION AND RESOURCE UTILIZATION 1 -DAMSITE SELECTION This section summarizes the previous site selection studies 1nd the studies done during the Alaska Power Authority Susitna Hydroelectric Project Feasibility Study. Additional detail on this topic can be found in Reference 1. 1.1 -Previous Studies Prior to the undertaking of the Susitna Hydroelectric Project Feasi- bility Study by the applicant, the hydroelectric development potential of the Alaskan Railbelt had been studied by several entities. (a) ~arly Studies of Hydroelectric· Potential Shortly after World ~~ar II ended, the United States Bureau of Reclamation (USBR) conducted an initial investigation of hydro- ilectric potential in Alaska and issued a report of the results in 1948. Responding to a recommendatio~ made in 1949 by the nine- teenth Alaska territorial legislature that Alaska be included in the Bureau of Reclamation program, the Secretary of Interior prc- vided funds to update the 1948 work. The resulting report, issued in 1952, recognized the vast hydroelectric potential within the territory and placed particular emphasis on the strategic location of the Susitna River between Anchorage and Fairbanks as well as its proximity to the connecting Railbelt (Figure B.1). A series of studies was commissioned over the years to identify damsites and conduct geotechnical investigations. By 1961, the Department of the Interior proposed authorization of a two-dam power system on the Susitna River involving the Devil Canyon and the Denali sites (Figure B.2). The definitive 1961 report was subsequently updated by the Alaska Power Administration (an agency of the USBR) in 1974, at which time the desi~ability of proceeding with hydroelectric development was reaffirmed. The Corps of EnginPers {COE) was also active in hydropower invest- igations in Alaska during the 1950s and 1960s, but focused its attention on a more ambitious development at Rampart on the Yukon River. This project was capable of generating five times as much annual electric energy as the prior Susitna proposal. The sheer size and the technological challenges associated with Rampart cap- tured the imagination of supporters and effectively diverted attention from the Susitna Basin for more than a decade. The Rampart report was finally shelved in the early 1970s because of strong environmental concerns and the uncertainty of marketing prospects for so much energy, particularly in light of abundant 1-1 .. • I ~' ~:,.r I -r-·'-1 natural gas which had been discovered and developed in Cook Inlet .. The energy cr1s1s precipitated by the OPEC oil boycott in 1973 provided some further impetus for seeking development of renewable resources. Federal funding was made available both to complete the Alaska Power Administration's update report on Susitna in 1974 and to launch a prefeasibility investigation by the COE. The State of Alaska itself commissioned a reassessment of the Susitna Project by the Henry J .. Kaiser Company in 1974. Salient features of the various reports to date are outlined in the following sections. {b) U.S. Bureau of Reclamation -1953 Study (c) The USBR 1952 report to the Congress on Alaska's overall hydro- electric potential was followed shortly by the first major study of the Susitna Basin in 1953. Ten damsites were identified above the railroad crossing at Gold Creek. These sites are identified on Figure B.2, and are listed below: -Gold Creek; -Olson; -Devil Canyon; -Devil Creek; -Watana; -Vee; -Maclaren; -Denali; -Butte Creek; and -Tyone (on the Tyone River). Fifteen more sites were considered below Gold Creeko However, more attention has been focused over the years on the Upper Susitna Basin where the topography is better suited to dam con- struction and where less impact on anadromous fisheries is ex- pected. Field reconnaissance eliminated half the original Upper Basin list, and further USSR consideration centered on Olson, Devil Canyon, Watana, Vee, and Denali. All of the USBR studies since 1953 have regarded these sites as the most appropriate for further investigation. U.S. Bureau of Reclamation -1961 Study In 1961 a more detailed feasibility study resulted in a recom- mended five-stage development plan to match the load growth curve as it was then projected. Devil Canyon was to be the first development--a 635-foot-high arch dam with an installed capacity of about 220 M~~. The reservoir formed by the Devil Canyon dam 1-2 f1 't ' ..... alone would not store enough water to permit higher capacities to be economically installed, since long periods of relatively low flow occur in the winter months. The second stage would have increased storage capacity by adding an earthfill dam at Denali in the upper reaches of the basin. Subsequent stages involved adding generating capacity to the Devil Canyon dam. Geotechnical investigations at Devil Canyon were more thorough than at Denali. At Denali, test pits were dug, but no drilling occurred. (d) Alaska Power Administration -1974 Little change from the basic USBR-1961, five-stage concept appeared in the 1974 report by the Alaska Power Administration. This later effort offered a more sophisticated design, provided new cost and schedule estimates, and addressed marketing, eco- nomics, and environmental considerations. (e) Kaiser Proposal for Development The Kaiser study, commissioned by the Office of the Governor in 1974, proposed that the initial Susitna development consist of a single dam known as High Devil Canyon located on Figure 8.2. No field investigations were made to confirm the technical feasibil- ity of the High Devil Canyon location because the funding level was insufficient for such efforts. Visual observations suggested the site was probably favorable. The USSR had always been uneasy about foundation conditions at Denali, but had to rely upon the Denali reservoir to provide storage during long periods of low flow. Kaiser chose to avoid the perceived uncertainty at Denali by proposing to build a rockfill dam at High Devil Canyon v1hich, at a height of 810 feet, would create a large enough reservoir to overcome the storage problem. Although the selected sites were different, the COE reached a similar conclusion when it later chose the high dam at Watana as the first to be constructed. . Subsequent developments suggested by Kaiser included a downstream dam at the 01 son site and an upstream dam at a site known as Susitna III (Figure 8.2). The information developed for these additional dams was confined to estimating energy potential. As in the COE study, future development of Denali remained a possibility if foundation conditions were found to be adequate and if the value of additional firm energy provided economic justification at some later date. (f) U.S. Army Corps of Engineers -1975 and 1979 Studies The most comprehensive study of the Upper Susitna Basin prior to the current study was completed in 1975 by the COE. A total of 23 alternative developments were analyzed, including those proposed by the USBR, as well as consideration of coal as the primary 1-3 ;;a J energy source for Railbelt electrical needso The COE agt'eed that an arch dam at Devi 1 Canyon was appropriate, but found that a high dam at the Watana site would form a large enough reservoir for seasonal storage and would permit continued generation during low flow periods. The COE recommended an earthfill dam at ~latana with a height of 810 feet. In the longer term, development of the Denali site re- mained a possibility which, if constructed, would increase the amount of firm energy available in dry years. An ad hoc task force was created by Governor Jay Hammond upon com- pletion of the 1975 COE Study. This task force re~commended en- dorsement of the COE request for Congressional authorization, but pointed out that extensive further studies, particularly those dealing with environmental and socioeconomic questions, were necessary before any construction decision could be made. At the federal 1 evel, concern was expressed at the Office of Man- agement and Budget regarding the adequacy of geotechnical data at the Watana site as well as the validity of the economics. The apparent ambitiousness of the schedule and the feasibility of a thin arch dam at Oev~l Canyon were also questioned. Further in- vestigations were funded and the COE produced an updated report in 1979. De vi 1 Canyon and Watana were reaffirmed as appropriate sites, but alternative dam types were investigated. A concrete gravity dam was analyzed as an a:lternative for the thin arch dam at Devi 1 Canyon and. the Watana dam was changed from earthfi 11 to rockfill. Subsequent cost and schedule estimates still indicated economic justification for the pr·oject. 1.2 -Plan Formulation and Selection M'ethodology The proposed plan which is the subject of this license application was selected after a review and reassessment of all previously considered sites. Additional detail in support of the findings in this Exhibit is found in Reference 5. This section of the report outlines tht: engineering and planning studies carried out as a basis for formulation of Susitna Basin devel- opment plans and selection of the preferred plan. In the description of the planning process, certain plan components and processes are frequently discussed. It is appropriate that three par- ticular terms be clearly defined: Oamsite -An individual potential damsite in the Susitna Basin, referred to in the generic process as "candidate. 11 1-4 '. ' ,. C\;,.. " I . .I { I : .,. , .: . . . · .. • \ . 1 ' · •,\ 1 • . I l ' Basin Development -A plan for developing energy within the Upper Plan Susitna Basin involving one or more dams, each of specified height, and corresponding power plants of specified capacity. Each plan is identified by a plan number and subnumber indicating the staging sequence to be followed in developing the full potential of the plan over a period of time. Generation - A specified sequence of implementation of power Scenario generation sources capable of providing sufficient power and energy to satisfy an electric load growth forecast for the 1980-2010 period in the Railbelt area. This sequence may include dif- ferent types of generation sou~ces such as hydro- electric and coal, gas or oil-fired thermal. These generation scenarios were developed for the comparative evaluations of Susitna Basin genera- tion versus alternative methods of generation. In applying the generic plan formulation and selection methodology, five basic steps are required; defining the objectives, selecting can- didates, screening, formulation of development plans! and, finally,, a detailed evaluation of the plans (Figure 8.3). The objective is to determine the optimum Susitna Basin development plan. The various steps 'required are outlined in subsections of this section. Throughout the planning process, engineering layout studies were made to refine the cost estimates for power generation facilities or water storage development at several damsites within the basin. These data were fed into the screening and plan formulation and evaluation studies. The second objective, the detailed evaluation of the various plans, is satisfied by comparing generation scenarios that include the selected Susitna Basin development plan with alternative generation scenarios, including all-thermal and a mix of thermal plus alternative hydropower developmentso 1.3 -Damsite Selection In previous Susitna Basin studies, twelve damsites were identified in the upper portion of the basin, i.e., upstream from Gold Creek. These sites are listed in Table 8.1 with relevant data concerning facilities, cost, capacity, and energy. The longitudinal profile of the Susitna River and typical reservoir levels associated with these sites are shown in Figure 8.4. Figure 8.5 illustrates which sites are mutually exclusive, i$e., those which can- not be developed jointly, since the downstream site would inundate the upstream site. 1-5 '.··.~ ' i :lf ·"'1! ri . ' It can b1~ readily seen that there are several mutually exclusive schemes for power development of the basin. The development of the Watana s·nte precludes development of High Devil Canyon, Devils Creek, Susitna III and Vee but fits well with Devil Canyon. Conversely, the High Dev·n Canyon site would preclude Watana and Devi 1 Canyon but fits well with Olson and Vee or Susitna III. These downstream sites do not preclude development of the upstream storage sites Denali or Butler Creek and Maclaren. All rele\eant data concerning dam type, capital cost, power, and energy output wE:r·e assembled and are summarized in Table B.l. For the Devil Canyon, High Devil Canyon, Watana, Susitna III, Vee, Maclaren, and Denali sites, conceptual engineering layouts were produced and capital costs were estimated based on calculated quantities and unit rates. Detailed analyses were also undertaken to assess the power capability and energ1,y yields. At the Gold Creek, Devil Creek, Maclaren, Butte Creek, and Tyone sites, no detailed engineering or energy studies were undertaken; data from previous studies were used with capital cost estimates updated in 1980 levels. Approximate estimates of the potential average energy yield at the Butte Creek and Tyone sites were undertake:n to assess the relative importance of these sites as energy producers. The data presented in Table B.l show that Devil Canyon, High Devil Can- yon, and Watana are the most economic 1 arge energy producers in the basin. Sites such as Vee and Susitna III have only medium energy pro- duction, and are slightly more costly that the previously mentioned damsites'. Other sites such as Olson and Gold Creek are competitive provided they have additional upstream regulation. Sites such as Denali and Maclaren produce substantially higher cost energy than the other sites but can also be used to increase regulation of flow for downstrea.m use. (a) Site Screeni~ The objective of this screening process was to eliminate sites which would obviously not be included in the initial stages of the Susitna Basin development plan and which, therefore, did not deserve further study at this stage. Three basic screening criteria were used: environmental, alternative sites, and energy contribution. The :screening process involved eliminating all sites falling in the unacceptable environmental impact and alternative site cate- gories. Those failing to meet the energy contribution criteria were also eliminated unless they had some potential for upstream regulation. The results of this process, described in detail in Reference 5, are as follows: 1-6 • I • ' • ' ' ~ . ' ~. . , • I' ' ~ • /1 ... -' .. ,.. ; ~--··--·-' ·--.. ...--...... -... _.~,__--~ ....... ·---...--~·~, ~-~· ' -~..,._:_---~· ~=---..,--~ .. -................... -,.....i.,;__;_~---~~,..., . -The 11 Unacceptable site" environmental category eliminated the Gold Creek, Olson, and Tyone sites. -The alternative sites category eliminated the Devil Creek and Butte Creek sites. -No additional sites were eliminated for failing to meet the energy contribution criteria. The remaining sites upstream from Vee, i.e., Maclaren and Denali, were retained to insure that further study be directed toward determining the need and viabi- lity of providing flow regulation in the headwaters of the Susitna. (b) Engineering Layouts In order to obtain a uniform and reliable data base for studying the seven sites remaining, it is necessary to develop engineering layouts and reevaluate the costs. In addition, staged develop- ments at several of the larger dams were studied. The basic objective of these layout studies was to establish a uniform and consistent development cost for each site. These lay- outs are consequently conceptual in nature and do not necessarily represent optimum project arrangements at the sites. Also, be- cause of the lack of geotechnical information at several of the sites, judgmental decisions had to made on the appropriate founda- tion and abutment treatment. The accuracy of cost estimates made in these studies is of the order of plus or minus 30 percent. (i) Design Assumptions In order to maximize standardization of the layouts, a set of basic design assumptions was developed. These assump- tions covered geotechnical, hydrologic, hydraulic, civil, mechanical, and electrical considerations and were used as guidelines to determine the type and size of the various components within the overall project layouts. As stated previously, other than at Watana, Devil Canyon, and Denali, little information regarding site conditions was available. Broad assumptions were made on the basis of the limited data, and those assumptions and the interpretation of data have been conservative. It was assumed that the relative cost differences between rockfill and concrete dams at the site would either be marginal or greatly in favor of the rockfill. The more detailed studies carried out subsequently for the Watana and Devil Canyon sites support this assumption. Therefore, a rockfill dam has been assumed at all developments in order to eliminate cost discrepancies that might result from a consideration of dam-fill unit costs compared to concrete unit costs at alternative sites. l.a7 .. !Jil s ' j L ~ • l '-' -,) '·-'" ------·------------~--,-~~~--~---~-------~--------~~ (ii) General Arrangements A brief description of the general arrangements developed for the various sites is given t2iow. Descriptions of Watana and Devil Canyon in this section are of the prelim- inary layouts and should not be confused with the proposed layouts in Exhibit A and Exhibit F. Figures 8.6 to 8.12 illustrate the layout details. Table 8.3 summarizes the crest 1 eve~ 1 s and dam heights considered. In laying out the developments, conservative arrangements have been adopted, and whenever poss i b 1 e there has been a general standardization of the component structures. -Devil Canyon (Figure 8.6) The development at Devil Canyon, located at the upper end of the canyon at its narrowest point, consists of a rock- fill dam, single spillway, power facilities incorporating an underground powerhouse, and a tunnel diversion. The rockfill dam would rise above the valley on the south abutment and terminate in an adjoining saddle dam of simi- lar construction. The dam would be 675 feet above the lowest foundation level with a crest elevation of 1470 and a volume of 20 million cubic yards. The spi-llway would be located on the north bank and would consist of a gated overflow structure and a concrete-1 ined chute linking the overflow structure with intermediate and terminal stilling basins. Sufficient spillway capacity would be provided to pass the Probable Maximum Flood safely. The power facilities would be located on the north abut- ment. The massive intake structure would be founded with- in the rock at the end of a deep approach channel and would consist of four integrated units~ each serving individual tunnel penstocks. The powerhouse would house four 150-MW vertically mounted Francis type turbines driv- ing overhead 165 MVA umbrella type generators. As an alternative to the full power development in the first phase of construction, a staged powerhouse alternative was also investigated. The dam would be com- pleted to its full height but with a initial plant installed capacity in 300-MW range. The complete power- house would be constucted together with penstocks and a tailrace tunnel for the initial two 150-MW units, together with concrete foundations for the future units. 1-8 .. Watana (Figure B.7 and B.8) For initial comparative study purposes, the dam at Watana is assumed to be a rockfill structure located on a similar alignment to that proposed in the previous COE studies. It would be similar in construction to the dam at Devil Canyon with an impervious core founded on sound bedrock and an outer she 11 composed of b 1 as ted rock excavated from a single quarry located on the south abutment. The dam would rise 880 feet from the lowest point on the foundation and have an overall volume of approximately 63 million cubic yards for a crest elevation of 2225. The spillway would be located on the north ·bank and would be simi 1 ar in concept to that at Devi 1 Canyon with an intermediate and terminal stilling basin. The power facilities located within the south abutment with similar intake, underground powerhouse, and water passage concepts to those at Devi 1 Canyon would incorporate four 200-MW turbine/generator units giving a total output of 800-MW. As an alternative to the initial full development at Watana, staging alternatives were investigated. These included staging of both dam and powerhouse construction. Staging of the powerhouse would be similar to that at Devil Canyon, with a Stage I installation of 400-MW and a further 400-MW in Stage II. In order to study the alternative dam staging concept it was assumed that the dam would be constructed for a maxi- mum operating water surface elevation some 200 feet lmver than that in the final stage (Figure B.8). The powerhouse would be completely excavated to its final size during the first stage. three oversized 135-MW units would be installed together with base concrete for an additional unit. A low level control structure and twin concrete-lined tunnels leading into a downstream stilling basin would form the first stage spillway. For the second stage, the dam \voul d be comp 1 eted to its full height, the impervious core would be appropriately raised, and additional rockfill would be placed on the downstream face. It was assumed that before construction commences the top 400 feet of the first stage dam would be removed to ensure the complete integrity of the impervious cort:. for the raised dam. A second spillway control struc- ture would be constructed at a higher level and would in- 1-9 corporate a downstream chute 1 eading to the Stage I spillway structure. The original spillway tunnels would be closed with concrete plugs. A new intake structure would be constructed utilizing existing gates and hoists, and new penstocks would be driven to connect with the existing ones. The existing intake would be sealed off. One additional 200 MW unit would be installed and the required additional penstock and tailrace tunnel constructed. The existing 135-MW units would be upgraded to 200 MW. -High Devil Canyon (Figure 8.9) The development would be located between Devil Canyon and Watana. The 855 feet high rockf·ill dam \'/ould be similar in design to Devil Canyon, containing an estimated 48 million cubic yards of rockfill with a crest elevation of 1775. The south bank spillway and the north bank powerhouse facilities would also be similar in concept to Devil Canyon, with an installed capacity of 800-~1W. Two stages of 400-~1W were envisaged in each v.Jhich would be undertaken in the same manner as at Devil Canyon, with the d~m initially constructed to its full height. -Susitna, III (Figure 8.10) The development would involve a rockfi11 dam with an impervious core approximately 670 feet high, a crest ele- vation of 2360, and a volume of approximately 55 million cubic yards. A concrete-lined spillway chute and a single stilling basin would be located underground~ with the two diversion tunnels on the south bank. -Vee (Figure 8.11) A 610 feet high rockfill dam founded on bedrock with a crest elevation of 2350 and total volume of 10 million cubic yards was considered. Since Vee is located further upstream than the other major sites the flood flows are correspondingly lower, thus allowing for a reduction in size of the spillway facili- ties. A ~pillway utilizing a gated overflow structu~e, chute, and flip bucket was adopted. The power facilities would :onsist of a 400-MW underground powerhouse located in the south bank with a tailrace outlet well downstream of the main dam. A secondary rockfill dam would also be required in this vicinity to seal off a low point. Two diversion tunnels would be provided on the north bank. 1-10 I I J j j J J J . J J J -Maclaren (Figure B.12) The development would consist of a 185 feet high earthfill dam founded on pervious riverbed materials. The crest elevation of the dam would be 2405. This reservoir would essentially be used for regulating purposes. Diversion would occur through three conduits located in a open cut on the south bank and floods would be discharged via a side chute spillway and stilling basin on the north bank. -Denali (Figure 8.12) Denali is similar in concept to Maclaren. The dam would be 230 feet high, of earthfill construction, and would have a crest elevation of 2555. As for Maclaren, no generating capacity would be included. A combined diver- sion and spillway facility would be provided by twin con- crete conduits founded in open cut excavation in the north bank and discharging into a common stilling basin. (c) Capital Costs For purposes of initial comparisons of alternatives, construction quantities were determined for items comprising the major works and structures at the site. Where detail or data were not suffi- cient for certain work, quantity estimates were made on the basis of previous Acres• experience and the general knowledge of site conditions reported in the literature. In order to determine total capital costs for various structures, unit costs have been developed for the items measured. These have been estimated on the basis of review of rates used in previous studies, and of rates used on similar works in Alaska and elsewhere. Where appli- cable, adjustment factors based on geography, climate, manpower and accessibility were used. Technical publications have also been reviewed for basic rates and escalation factors. The total capital costs developed are shown in Tables B.l and B.2. It should be noted that the capital costs for Maclaren and Denali shown in Table 8.1 have been adjusted to incorporate the costs of generation plants with capacities of 55-MW and 60-MW, respec- tively. Additional data on the projects are summarized in Table 8.3. 1.4 -Formulation of Susitna Basin Development Plans The results of the site screening process described above indicate that the Susitna Basin development plan should incorporate a combination of several major dams and powerhouses located at one or more of the fol-lowing sites: 1-11 .. ' .. ' . __ · .·• •· ··--... -_~.:-~· ·-'"=>.·.-_ ·' •• . .. ~ ._ . _.:.... .. . . ... ·. . . ~.. ... .,. ~ .. ':'::./-:..: .. , ·- ~' \., :_,. -Devi 1 Canyon; -High Devil Canyon; -Watana; -Susitna III; or -Vee. Supplementary upstream flow regulation could be provided by structures at: -Maclaren; and -Denali. Cost estimates of these projects are itemized on Table 8.4. A computer assisted screening process identified the plans that are most economic as those of Devil Canyon/Watana or High Devil Canyon/Vee. In addition to these two basic development plans, a tunnel scheme which provides potential environmental advantages by replacing the Devil Can- yon dam with a long power tunnel and a development plan involving Watana Dam was also introduced. The criteria used at this stage of the process for selection of pre- ferred Susitna Basin development plans are mainly economic (Figure B.3). Environmental considerations are incorporated into the further assessmert of the plans finally selected. The results of the screening process are shown in Table B.S. Because of the simpl ifyi.lS assumptions that were made in the screening model, the three best solutions from an economic point o..;; view are included in the table. The most important conclusions that can be drawn are as follows: -For energy requirements of up to 1,150 Gwh, the High Devil Canyon, D~vil Canyon or the Watana sites individually provided the most eco- nnmic energy. The difference between the costs shown on Table B.4 is around 10 percent, which is similar to the accuracy that can be expected from the screening model. --For energy requirements of between 1, 750 and 3, 500 Gwh, the High Devil Canyon site is the most economic. -For energy requirements of between 3,500 and 5,250 Gwh the combina- tions of either Watana and Devil Canyon or High DevJl Canyon and Vee are most economic. -The total energy production capability or the Watana/Devil Canyon development is considerably larger than that of th2 High Devil Canyon/Vee alternative and is the only plan capable of meeting energy demands in the 6,000 Gwh range. 1-12 (a) Tunnel Alternative A scheme involving a long power tunnel could conceivably be used to replace the Devil Canyon dam in the Watana/Devil Canyon development plan. It could develop similar head for power genera- tion and may provide some environmental advantages by avoiding inundation of Devil Canyon. Obviously~ because of the low winter flows in the river, a tunnel alternative could be considered only as a sc~ond stage to the Watana development. Conceptually, the tunnel alternatives would comprise the following major components in some combination, in addition to the Watana dam reservoir and associated powerhouse: -Power tunnel intake works; -One or two power tunnels of up to forty feet in diameter and up to thirty miles in length; - A surface or underground powerhouse with a capacity of up to 1200 MW; - A re-regul at ion dam if the intake works are located downstream from Watan a; and -Arrangements for compensation flow in the bypassed river reach. Four basic alternative schemes were developed and studied. Figure 8.13 is a schematic illustration of these schemes. All schemes assumed an initial Watana development with full reservoir supply level at Elevation 2200 and the associated powerhouse with an installed capacity of 800 MW. Table 8.6 lists all the pertinent technical information. Table B.7 lists the power and energy yields for the four schemes. Table 8.8 itemizes the capital cost estimate. Based on the foregoing ~conomic information, Scheme 3 (Figures 8.14 and 8.15) produces the lowest cost energy by a factor of nearly 2. A review of the environmental impacts associated with the four tunnel schemes indicates that Scheme 3 would have the least impact, primarily because it offers the best opportunities for regulating daily flows downstream from the project. Based on this assessment and because of its almost 2 to 1 economic advantage, Scheme 3 was selected as the only scheme worth further study (see Development Selection Report for detailed analysis). The capital cost es~imate for Scheme 3 appears in Table 8.8. The estimates also incorporate single and double tunnel options. For purposes of these studies, the double tunnel option has been selected 1-13 • • because of its superior reliability. It should also be recognized that the cost estimates associated with the tunnels are probably subject to more variation than those associated with the dam schemes due to geotechnical uncertainties. I~ an attempt to compensate for these uncertainties, economic sensitivity analyses using both higher and lower tunnel costs have been conducted. (b) ~dditional Basin Development Plan As noted, the Watana and H'i gh Devi 1 Canyon dams ites appear to be individually superior in economic terms to all others. An additional plan was therefore developed to assess the potential fpr developing these two sites together. For this scheme, the Watana dam would be developed to its full potential. The High Devil Canyon dam would be constructed to a crest elevation of 1470 to fully utilize the head downstream from Watana. (c) Selected~ Basin Development Plans The essential objective of this step in the development selection prot;ess is defined as the identification of those plans which appear to warrant further, more detailed evaluation. The results of the final screening process indicate that the Watana/Devil Canyon and the High Devil Canyon/Vee plans are clearly superior to all other dam combinations. In addition, it was decided to study further Tunnel Scheme 3 as an alternative to the High Devil Canyon darn and a p 1 an cotnbi ni ng Watana and High De vi 1 Canyon. Associated with each of these p 1-l!.lS are sever a 1 options for staged development. For this more detailed analysis of these basic plans, a range of different approaches to staging the developments was considered. In order to keep the total options to a reason- able number and also to maintain reasonably large staging step5 consistent with the total development size, staging of only the two larger d9velopmen+s: i.e., Watana and High Devil Canyon, was considered. The basic staging concepts adopted for these develop- ments involved staging both dam and powerhouse construction, or alternatively just staging powerhouse construction. Powerhouse stages were considered in 400 MW increments. Four basic plans and associated subplans are briefly described below. Plan 1 involves the Watana/Oevil Canyon sites, Plan 2 the High Devil Canyon/Vee sites, Plan 3 the Watana-tunnel concept, and Plan 4 the Watana/High Dev11 Canyon siteso Under each plan several alternative subplans were identified, each involving a different staging concept. Summaries of these plans are given in Table B.9 .. 1-14 ( i) (ii) (iii) Plan 1 -Subplan 1.1: The first stage involves constructing Watana Dam to its full height and installing 800 MW. Stage 2 involves constructing Devil Canyon Dam and installing 600 MW. -Subp1an 1.2: For this Subplan, construction of the Watana Dam is staged from a crest elevation of 2060 to 2225. The powerhouse is also staged from 400 MW to 800 MW. As for Subplan 1.1, the final stage involves Devil Canyon with an installed capacity of 600 MW. -Subplan 1.3: This Subplan is similar to Subplan 1.2 except that only the powerhouse and not the dam at Watana is staged~ Plan 2 -Subplan 2.1: This Subplan involves constructing the High Devil Canyon Dam first with an installed capacity of 800 MW. The second stage involves constructing the Vee Dam with an installed capacity of 400 MW. Subplan ~.2: For this Subplan, the construction of High Devil Canyon is staged from a crest elevation of 1630 to 1775~ The installed capacity is also staged from 400 to 800 MW. As for Subplan 2.1, Vee folJows with 400 MW of installed capacity. Subp·.lan 2.3: This Subplan is similar to Subplan 2.2 except that only the powerhouse and not the dam at High Devil Canyon is staged. Plan 3 --- -Subplan 3.1: This Subplan involves initial co~struction of Watana and installation of 800 MW capacity. The next stage involves the construction of the downstream re- regulation dam to a crest elevation of 1500 and a 15 mile long tunnel. A total of 300 MW would be installed at the end of the tunnel and a further 30 MW at the reregulation dam. An additional 50 MW of capacity would be installed at the Watana powerhouse to facilitate peaking operations. -Subplan 3.2: This Subplan is essentially the same as Subplan 3.1 except that construction of the initial 800 MW powerhouse at Watana is staged. 1-15 .. • • tf • ~ • • • • • • . ~ • . . ' • • .. ... • \. • • • .·-• • I; • , i ., I .. ( i v) Plan 4 This single plan was developed to evaluate the development of the two most economic damsites, Watana and High Devil Canyon, jointly.. Stage 1 involves constructing Watana to its full height with an installed capacity of 400 MW~ Stage 2 involves increasing the capacity at Watana to 800 MW. Stage 3 involves constructing High Devil Canyon to a crest elevation of 1470 so that the reservoir extends to just downstream of Watana. In order to develop the full head between Watana and Portage Creek, an additional smaller dam is added downstream of High Devil Canyon. This dam would be located just upstream from Portage Creek so as not to interfere with the anadromous fisheries and would have a crest elevation of 1030 and an installed capacity of 150 MW~ For purposes of these studies, this site is referred to as the Portage Creek site. 1~5 -Evaluation_of Basin Development Plans The overall objective of this step in the evaluation process was to select the preferred basin development plan. A preliminary evaluation of plans was initially undertaken to determine broad comparisons of the available alternatives. This was followed by appropriate adjustments to the plans and a more detailed evaluation and comparison. In the process of initially evaluating the final four schemes, it became apparent that there waul d be en vi ronmenta 1 problems associ a ted with allowing daily peaking operations from the most downstream reser- voir in each of the plans described above. In order to avoid these potential problems while still maintaining operational flexibility to peak on a daily basis, re-regulation facilities were incorporated in the four basic plans. These facilities incorporate both structural measures such as re-regulation dams and modified operational pro- cedures. Details of these modified plans, referred to as E1 to E4, are listed in Table B.10. The plans listed in Table B.10 were subjected to a more detailed analysis as described in the following section. (a) Evaluation Methodology The approach to evaluating the various basin development plans described above is twofold: -For determining the optimum staging concept associated with each basic plan (i.e., the optimum subplan), only economic criteria are used and the least cost staging concept is adopted. 1-16 .. J c. •• For assessing which plan is the most appropriate, a more detailed evaluation proct?ss. incorporating economic, environmental, social and energy contribution aspects is taken into account. Economic evaluation of any Susitna Basin development plan requires that the impact of the plan on the cost of energy to the Railbelt area consumer be assessed on a systemwide basis. Since the con- sumer is supplied by a large number of different generating sources, it is necessary to determine the total Railbelt system cost in each case to compare the various Susitna Basin Jevelopment options. The primary tool used for system costs was the mathematical model developed by the Electricity Utility Systems Engineering Depart- ment of the General Electric Company. The model is commonly known as OGP5 or Optimized Generation Planning Model, Version 5. The following information is paraphrased from GE literature on the program~ The OGP5 program was developed over ten years to comb 1 ne the three main elements of generation expansion planning (system reliabil- ity, operating and investment costs) and automate generation addi- tion decision analysis. OGP5 will automatically develop optimum generation expansion patterns in terms of economics, reliability and operation. Many utilities use OGP5 to study load management, unit size, capital and fuel costs, energy storage, forced outage rates, and forecast uncertainty. The OGP5 program requires an extensive system of specific data to perform its planning function. In developing an optimal plan, the program considers the existing and corrmitted units (planned and under construction) available to the system and the characteris- tics of these units including age, heat \"ate, size and outage rates as the base gene~ration plan. The program then considers the given load forecast and operation criteria to determine the need for additional system capacity based on given reliability cri- teria. This determines 11 11ow much" capacity to add and mwhen" it should be installed. If a need exists during any monthly itera- tion, the program will consider additions from a list of alterna- tives and select the available unit best fitting the system needs. Unit selection is made by computing production costs for the sys- tem for each alternative included and comparing the results. The unit resulting in the lowest system production cost is select- ed and added to the system. Finally, an investment cost analysis of the capital costs is completed to answer the question of 11 What kind" of gener·ation to add to the system. The model is then further used to compare alternative plans for meeting variable electrical demands, based on system reliability and production costs for the study period. 1 ... 17 0 _fj ---;--.~--_:~-~--~t~~ -, .-:-.• • ,, A minor limitation inherent in the use of the OGP5 model is that the number of years of simulation is limited to 20. To overcome this, the s+~dy period of 1980 to 2040 has been broken into three separate segments for study purposes~ These segments are common to all system generation plans. The first segment has been assumed to be from 1980 to 1990. The model of this time period included all committed generation units and is assumed to be common to all generation scenarios. The end point of this model becomes the beginning of each 1990- 2010 model. The model of the first two time periods coosidered (1980 to 1990, and 1990 to 2010) provides the total production costs on a year- to-year basis. These total costs include, for the period of modeling, all costs of fuel and operation and maintenance of all generating units included as part of the system. In addition, the completed production costs include the annualized investment costs of any production plans added during the period of study. A number of factors which contribute to the ultimate cost of power to the consumer are not included in this model. These are common to all scenarios and include: -All investment costs to plants in service prior to 1981; -Costs of transmission systems in service both at the transmis- sion and distribution level; and Administrative costs of utilities for providing electric service to the public. Thus, it should be recognized that the production costs modeled represent only a portion of ultimate consumer costs and in effect are only a portion, albeit major, of total costs. The third period, 2010 to 2040, was modeled by assuming that pro- duction costs of 2010 would recur for the additional 30 years to 2040. This assumption is believed to be reasonable given the limitations on forecasting energy and load requirements for this period. The additional perio~ to 2040 is required to at least take into account the benefit derived or v a 1 ue of the addition of a hydroelectric power plant which has a useful life of fifty years or more. The selection of the preferred generation plan is based on numer- ous factors. One of these is the cost of the generation plan. To provide a consistent means of assessing the production cost of a given generation scenario, each production cost total has been converted to a 1980 present worth basis. The present worth cost 1-18 • of any generation scenario is made up of three cost amounts. The first is present worth cost (PWC) of the first ten years of study (1981 to 1990), the second is the PWC of the scenario assumed during 1990 to 2010 and the third the PWC of the scenario in 2010 assumed to recur for the period 2010 to 2040. In this way the long-term (60 years) PWC of each generation scenario in 1980 dollars can be compared. A summary of the input data to the model and a discussion of the • results follow. (i) Initial Economic Analyses Table B.11 lists the results of the first series of economic analyses undertaken for the basic Susitna Basin development plans listed in Table B.10. The information provided includes the specified on-line dates for the various stages of the plans, the OGP5 run index number, the total installed capacity at year 2010 by category, and the total system present-worth cost in 1980 for the period 1980 to 2040. Matching of the Susitna development to the load growth for Plans El, E2, and E3 is shown in Figure B.l6, B.l7 and 8.18 respectively. After 2010, steady state conditions are assumed and the then-existing generation mix and annual costs for 2010 are applied to the years 2011 to 2040. This extended period of time is necessary to ensure that the hydroelectric options being studied, many of which only come on-line around 2000, are simulated as operating for periods approaching their economic lives and that their full impact on the cost of the generation system is taken into account. -Plan El -Watana/Devil Canyon • Staging the dam at Watana (Plan E1.2) is not as economic as constructing it to its full height (Plan E1.1 and E1.3). The present worth advantage of not staging the dam amounts to $180 million in 1980 dollars. The results indic~te that, with the level of analysis performed, there is no discernible benefit in staging construction of the Watana powerhouse (Plan El.l and E1.3). However, Plan El.4 results indicates that, should the powerhouse size at Watana be restricted to 400 MW, the overall system present worth costs would increase. Additional runs performed for variations of Plan E1.3 indicate that system present worth would increase by $1,110 million if the Devil Canyon dam was not constructedc A five year delay in construction of the Watane dam would increase system present worth by $220 million. 1-19 ' • -• I .. • : • • • i. ~ • : ~ - ' • • ' • • ' -"'. ... • • .. ., ~ -·. ~ .. . . \. . 'j -~~;~~~~>~::: .... ~~:"~"· .. J ..,-.~~---~··~--·~-·-----·"'·····~··. ( ~ i) Plan E2 -High Dev·il Canyon/Vee The results for Plan E2.3 indicate that the system pre- sent worth is $520 million more than Plan E1.3. Present worth increases also occur if the Vee dam stage is not constructed. A reduction in present worth of approxi- mately $160 million is possible if the Chakachamna hydroelectric project is constructed instead of the Vee dam . . The results of Plan E2.1 indicate that total system present worth would increase by $250 million if the total capacity at High Devil Canyon Y~ere limited to 400 t"lW. -Plan E3 -Watana/Tunnel The results for Plan E3.1 illustrate that the tunnel scheme versus the Devil Canyon dam scheme (E1.3) adds approximately $680 million to the total system present worth cost. The availability of reliable geotechnical data would undoubtedly have improved the accuracy of the cost estimates for the tunnel alternative. For this reason, a sensitivity analysis was made as a check to determine the effect of halving the tunnel costs. This analysis indicates that the tunnel scheme is still more costly than constructing the Devil Canyon dam. -Plan E4 -Watana/High Devil Canyon/Portage Creek The results indicate that system present worth associated with Plan E4.1, excluding the Portage Creek site develop- ment, are $200 million ,more than the equivalent E1.3 plan. If the Portage Creek development is included, the present worth difference would be even greater. Load Forecast Sensitivity Analyses . . The plans with the lowest present-worth cost were subjected to further sensitivity analyses. The objective of the analysis was to determine the impact on the development decision of a variance in forecast. The load forecasts used for this analysis were made by ISER and are presented in Section 5.1 of this Exhibit. These results are summarized in Table B'"12. At the low load forecast, full capacity development of Watana-Devil Canyon Scheme 1.3 is not warranted. Under Scheme 1.4, the most economic development includes a 400 MW development at each site, as compared to Watana only. 1-20 .) I Similarly, it is more economic to develop High Devil Canyon and Vee, as compared to High Devil Canyon only, but at a total capacity of only 800 MW. At this level of projected demand, the Watana-Devil Canyon Plan is more economic than the High Devil Canyon-Vee Plan or any singular development ($210 million, present worth basis). As individual developments however, the High Devil Canyon only plan is slightly superior econom·ically than the Watana project ($90 million, present worth basis). At the high load forecast, the larger capacities are clearly needed. In addition, both the High Devil Canyon-Vee and Watana-Devil Canyon plans are improved economically by the addition of the Chackachamna project. This illustrates the superiority of the Chackachamna project to the additon of alternative coal and gas projects using the study price projections. Similar to the low load forecast, the Watana- Devil Canyon project is superior to the High ~evil Canyon-Vee alternative but the margin of difference on a present worth basis is much greater ($1.0 bill·ion, present worth basis). (b) Evaluation Criteria The following criteria were used to evaluate the shortlisted basin deveiopment plans. These criteria generally contain the require- ments of the generic process with the exception that an additional criterion, energy contribution, is added in ordei to ensure that full consideration is given to the total basin energy pot~ntial developed by the various plans. (i) Economic Plans were compared using long-term pres€nt worth costs) ca1culated using the OGP5 generation planning model. The parameters used in calcul a.ting the total present-worth cost of the total Railbelt generating system for the period 1980 to 2040 are listed in Table 8.13 and 8.14. Load forecasts used in the analysis are presented in Section 5.l(b). Environmental A qualitative assessment of the environmental impact on the ecological, cultut'al, and aesthetic resources is undertaken for each p1an. Emphasis is placed on identifying major concerns so that these could be combined with the other evaluation attributes in an over~ll assessment of the plan. 1-21 ' u (c) ( i i i ) Soc i a 1 This attribute includes determination of the potential non- renewable resource displacement, the impact on the state and local economy, and the risks and consequences of major structural failures due to seismic events. Impacts on the economy refer to the effects of an investment plan oneco- nomic variables. (iv) Energy Contribution The par&meter used is the total amount of energy produced from the specific development plan. An assessment of the energy development foregone is also undertaken. The energy loss that is inherent ~o the plan and cannot easily be recovered by subsequent staged developments is of greatest concern. Results of Evaluation Process The various attributes outlined above have been determined for each plan and are summarized in Tables 8.15 through 8.23. Some of the attributes are quantitative while others are qualitative. Overall evaluation is based on a comparison of similar types of attributes for each plan. In cases where the attributes associ- ated with one plan all indicate equality or superiority with respect to another plan, the decision as to the best plan is clear cut. In other cases where some attributes indicate superiority and others inferiority, differences are highlighted and trade-off decisions are made to determine the preferred development plan. In cases where these trade-offs have had to be made, they were relatively straightforward, and the decision-making process can, therefore, be regarded as effective and consistent. In addition, these trade-offs are clearly identified so that independent assessment can be made. The overall evaluation process is conducted in a series of steps. At each step, only two plans are compared. The superior plan is then taken to the next step for evaluation against a third plan. ( i) Devil Canyon Dam Versus T1mnel The first step in the process involves the comparison of the Watana-Devil Canyon dam plan (El.3) and the Watana-Tunnel plan (E3.1). Since Watana is common to both plans, the evaluation is based on a comparison of the Devi1 Canyon dam and the Scheme 3 tunnel alternative. 1-22 ". + • • ... • ' • • '. ' • • • ' ' • • -r' • 1 l ., I I I ! I In order to assist in the evaluation in terms of economic criteria, additional information obtained by analyzing the results of the OGP5 computer runs is shown in Table 8.15. This information illustrates the breakdown of .the total system present worth cost in terms of capital investment, fuel, and operation and maintenance costs. -Economic Comparison From an economic point of view, the Watana-Devil Canyon dam scheme is superior. As summarized in Tables 8.15 and 8.16, on a present worth basis the tunnel scheme is $680 million more expensive than the dam scheme. For a low demand growth rate, this cost difference would be reduced slightly to $650 million. Even if the tunnel scheme costs are halved, the total cost difference would still amount to $380 million. As highlighted in Table 8916 considera- tion of the sensitivity of the basic economic evaluation to potential changes in capital cost estimates, the period of economic analysis, the discount rate, fuel costs, fuel cost escalation: and economic plant life do not change the basic economic superiority of the dam scheme over the tunnel scheme. -Environmental Comparison The environmental comparison of the two schemes is sum- marized in Table 8.17. Overall, the tunnel scheme is judged to be superior because: . It offers the potential for enhancing anadromous fish populations downstream of there-regulation dam due to the more uniform flow distribution that will be achieved in this reach; . It would inundate 13 mi 1 es 1 ess of resident fisheries habitat in river and major tributaries; It has a lower potential for inundating archeological sites due to smaller reservoir involved; and . It would preserve much of the characteristics of the Devil Canyon gorge which is considered to be an aesthe- tic and recreational resource. -Social Comparison Table 8.18 summarizes the evaluation in terms of the social criteria of the two schemes. In terms of impact on state and local economics and risks because of seismic 1-23 } I I :i I D ( i i) I I I I I J i exposure, the two schemes are rated equal. However, the dam scheme has, due to its higher energy yield, more potential for displacing nonrenewable energy resources, and therefore has a slight overall advantage in terms of the social evaluation criteria. -Energy Comparison Table 8.19 summarizes the evaluation in terms of the energy contribution criteria. The results show that the dam scheme has a greater potential for energy production and develops a larger portion of the basin's potential. The dam scheme is therefore judged to be superior from the energy contribution standpoint. -Overall Comparison The overall evaluation of the two schemes is summarized in Table 8.20. The estimated cost saving of $680 million in favor of the dam scheme plus the additional energy pro- duced are considered to outweigh t reduction i~ the overall environmental impact of th\ •Jnnel scheme. The dam scheme is therefore judged to be superior overal!. Watana-Devil Canyon Versus High Qevil Canyo~-Vee The second step in the development selection process involves an evaluation of the Watana-Devil Canyon (E1.3) and the High Devil Canyon-Vee (E2.3) development plans. -Economic Comparison In terms of the economic criteria (see Table 8.15 and 8.16) the Watana-Devil Canyon plan is less costly by $520 million. Consideration of the sensitivity of this deci- sion to potential changes in the various parameters con- sidered (i.e., load forecast, discounted rates, etc.) does not change the basic superiority of the Watana-Devil Canyon p 1 an. Under the low load-growth forecast, the Watan&-Devil Canyon plan is favored by only $210 million. While under the high load-growth forecqst the advantage is $1040 million. -Environmental Comparison The evaluation in terms of the environmental criteria is summarized in Table 8.21~ In assessing these plans, a reach-by-reach comparison was made for the section of the 1-24 .. ! Susitna River between Portage Creek and the Tyone River. The Watana-Devil Canyon scheme would create more potential environmental impacts in the Watana Creek area. However, it is judged that the potential environmental impacts whi:h would occur above the Vee Canyon dam with a High Devil Canyon-Vee development are more severe in overall comparison. Of the seven environmental factors considered in Table B.17, except for the increased loss of river valley, bird and black bear habitat, the Watana-Devil Canyon development plan is judged to be more environmentally acceptable than the High Canyon-Vee plan. The other six area.s in which Watana-Devil Canyon was judged to be super·ior ar·e fisheries, moose, caribou, furbearers, cultm·al resources, aesthetics, and land use. -Energy Comparison The evaluation of the two plans in terms of energy contri- bution criteria is summai'ized in Table B.22. The t~atana­ Devil Canyon scheme is assessed to be superior because of its higher energy potential and the fatt that it develops a higher proportion of the basin's ene~gy potential. The Watana-Devil Canyon plan annually develops 1160 GWh and 1650 GWh ~ore average and firm energy respectively than the High Devil Canyon-Vee plans~ -S~c:: 1 a l Compar::.i son T~L1e 3.18 summari~es the evJluation in terms of the soc1Jl criteria. As in the case of the dam versus tunnel comparison, the Watana-Devil Canyon plan is judged to have a slight advantage over the High Devil Canyon-Vee plan. This is because of its greater po .. :ential for displacing nonrenewable resources. In other social impact areas there are minimal ·differences between plans. 1.6 -Preferred Susitna Basin Development Plan One-on-one cornpar·i sons of the Watana-Devi l Canyqn plan with the Watana- tunnel plan and the High Devil Canyon-Vee plans are judged to favor the Watana-Devil Canyon plan in each case. The Watana-Devil Canyon plan was therefore selected as the preferred Sus·itna Basin development plan, and the basis for continuation of more detailed design optimization and environmental studies. 1-25 .. ' I I I' I I I 2 -ALTERNATIVE FACILITY DESIGN~ PROCESSES AND OPERATIONS .. I I I I 2c-ALTERNATIVE FACILITY DESIGNS, PROCESSES AND OPERATIONS 2.1 -Susitna Hydroelectric Development As originally conceived the Watana project initially comprised an earthfill dam with a crest elevation of 2225 and 400 MW of generating capacity scheduled to commence operation in 1993. An additional 400 MW would be brought on-line in 1996. At Devil Canyon an additional 400 MW vJould be installed to commence operation in the year 2000. Detailed studies of each project have led to refinement and optimization of designs in terms of a number of key factors, including updated load forecasts and economics. Geotechnical and environmental constraints identified as a resu1t of continuing field work have also greatly influenced the currently recommended design concepts. Plan formulation and alternative facility designs considered for the Watana and Devil Canyon developments are discussed in this section. Background information on the site characteristics as well as additional detail on the plan formu1ation process are included in the Supporting Design Report of Exhibit F and the referenced reports. 2.2 -Watana Project Formulation This section describes the evolution of the general arrangement of the Watana project which, together with the Devil Canyon project, comprises the development plan proposed. The process by which reservoir operat- ing levels and the installed generating capacity of the power facil- ities were established is presented, together with the means of hand- ling floods expected during construction and subsequent project opera- tion. The main components of the Watana development are as follows: -Main dam; -Diversion facilities; -Spillway facilities; -Outlet facilities; -Emergency release facilities; and -Power facilities. A number of alternatives are available for each of these components and they can be combined in a number of ways. The following paragraphs 2-1 • .. • !! f,..t,_"_·. ._, .. ". ~ .:,;~;. .. :~ l ! j J ~ I i ~ ~ I I I I I I l l t ~ '. describe the various components and methodology for the preliminary, intermediate, and final screening and review of alternative general arrangement of the components, together with a brief description of the selected scheme. This section presents the alternative arrangements studied for the Watana project. (a) Selection of Reservoir Levels TI1e selected elevation of the Watana dam crest is based on consid- erations of the value of the hydroelectric energy produced from the associated reservoir, geotechnical constraints on reservoir levels, and freeboard requirements. Firm energy, average annual energy, construction costs, and operation and maintenance costs were determined for the Watana development with dam crest eleva- tions of 2240, 2190, and 2140. The relative value of energy pro- duced in terms of the present worth of the long-term production costs (LTPW) for each of these three dam elevations was determined by means of the OGP5 generation planning model described in Section 1 of this Exhibit. The physical constraints imposed on dam height and reservoir elevation by geotechnical considerations were reviewed and incorpor-ated into the crest elevation selection process. Finally, freeboard requirements for the PMF and settle- ment of the dam after construction or as a result of seismic activity were taken into account. (i) Methodolog~ Firm and aver' age annual energy produced by the Sus itna development are based on 32 years of hydrological records. The energy produced was determined by using a multi- reservoir simulation of the operation of the Watana and Devil Canyon reservoirs. A variety of reservoir drawdowns were examined, and drawdowns producing the maximum firm energy consistent with engineering feasibility and cost of the intake structure were selected. Minimum flow require- ments were established at both project sites based on down- stream fisheries considerations. To meet system demand the required maximum generating capa- bility at Watana in the period 1994 and 2010 ranges from 665 MW to 908 MW. For the reservoir level determinations, energy estimates were made on the basis of assumed average annual cap1city requirements of 680 MW at Watan1 in 1994, increasing to 1020 MW at Watana in 2007, with an additional 600 MW at Devil Canyon coming online in the year 2002. The long term present worth costs of the generation system required to meet the Railbelt energy demand were then determined for each of the three crest elevations of the Watana dam using the OGP5 model. 2-2 . --~ • .. rl ij 1 ' J J 1 ~ I I I I I I I l J The construction cost estimates used in the OGP5 modeling proCE'!SS for the \~at ana and Devi 1 Canyon projects were based on preliminary conceptual layouts and construction sche- dules. Further refinement of these layouts has taken place during the optimization process. These refinements have no significant impact on the reservoir level selection. (ii) Economic Optimization Economic optimization of the Watana reservoir level was based on an evaluation of three dam crest elevations of 2240, 2190~ and 2140. These crest elevations applied to the central portion of the embankment with appropriate allowances for freeboard and seismic settlement, and correspond to maximum operating levels of the reservoir of 2215, 2165, and 2115 feet, respectively. Average annual energy calculated for each case using the reservoir simulation model are given ·in Table 8.24, together with corresponding project construction costs. In the determination of LTPW, the Susitna capital costs were adju£ted to include an allowance for interest during construction and then used as input to the OGP5 model. Simulateq annual energy yields were distributed on a monthly basis by the reservoir operation model to match as closely as possible the projected monthly energy demand of the Railbelt and then input to the OGP5 model. The LTPW of meeting the Railbelt energy demand using the Susitna devel- opment as the primary source of energy was then determined for each of the three reservoir levels. The results of these evaluations are shown in Table B.25, and plots showing the variation of the LTPW with dam crest elevation are shown in Figure B.19. This fig'.!i'"e indicates that on the basis of the assumptions used, the minimum LTPW occurs at a Watana crest elevation ranging from approxi- mately 2160 to 2200 (reservoir levels 2140 to 2180 feet). A higher dam crest will still result in a development which has an overall net economic benefit relative to thermal energy sources. However, it is also clear that as the height of the Watana dam is increased, the unit costs of additional energy produced at Watana is somewhat greater than for the displaced thermal energy source. Hence, the LTPW of the overall system would increase. Conversely, as the height of the dam is lowered, and thus Watana produces less energy, the unit cost of the energy produced by a thermal generation source to replace the lost Susitna energy is more expensive than Susitna energy. In this case also, the LTPW increases. 2-3 ... ] l ' . \J'. ' i (iii) Geotechnical Considerations On the north side of the reservoir created by the Watana dam a relict channel of considerable depth connects the reservoir to Tsusena Creek. As the water surface elevation of the reservoir is increased up to and beyond 2200 feet, a low area in the relict channel would require costly water retaining structures to be built and other measures to be taken. In addition to the cost the technical feasibility of these measures is not as certain as desired on a project of this magnitude. Because of the considerations relating to seismic stability, seepage problems and permafrost con- ditions in the relict channel area, the hydraulic head at the upstream end of the relict channel should.be limited wherever possible. By comparing normal reservoir levels plus flood surcharge to ground surface contours, it was determined that with normal reservoir level of 2185 and a small freeboard dike the following conditions would exist: -For flood magnitudes up to the 1:10,000-year event, there would be no danger of overtopping the lowest point in the relict channel. -For the PMF a freeboard dike in the low area of up to 10 feet in height would provide adequate protection. This dike would be wetted only a few days during a PMF event. -If seismic settlement or settlement due to permafrost melting did occur, the combination of the 10 feet free- board dike constructed on a suitable foundation plus normal reservoir level of 2185 feet would ensure that breakthrough in the relict channel area would not occur. With this approach, the Watana project will develop the maximum energy reasonably available without incurring the need for costly water retaining structures in the relict channel area. (iv) Conclusions It is important to establish clearly the overall objective used as a basis for setting the Watana reservoir level. An objective which would minimize the LTPW energy cost would lead to selection of a slightly lower reservoir level than an objective which would maximize the amount of energy which can be obtained from the available resource, while doing so with a technically sound project. The three values of LTPW developed by the OGP5 computer runs defined a relationship between LTPW and Watana dam 2-4 ... ,, ] ] J j ~ ' i I '4 il height which is relatively insensitive to dam height. This is highlighted by the curve of LTPW versus dam height in Figure 8.19. This figure shows there is only a slight var- iation in the LTPW for the range of dam heights included in the analysis. Thus, from an economic standpoint the opti- mum crest elevation could be considered as varying over a range of elevations from 2140 to 2220 with little effect on project economics. The main factors in establishing the upper limit of d(~ height were consequently the geotech- nical considerations discussed in (iii) above. The normal maximum operating level of the reservoir was therefore set at Elevation 2185, allowing the objective of maximizing the economic use of the Susitna resource still to be satisfied. (b) Selection of Installed Capacity The generating capacity to be installed at both Watana and Devil Canyon was determined on the basis of generati.on planning studies described in Sections 6 and 8 of Reference 4 together with appro- priate consideration of the following: -Available firm and average energy from Watana and Devil Canyon; -The forecast energy demand and peak load demand of the system; -Available firm and average energy fr'om other existing and com- mitted plant; -Capital cost and annual operating costs for Watana and Devil Canyon; -Capital cost and annual operating costs for alternative sources of energy and capacity; -Environmental constraints on reservoir operation; and -Turbine and generator operating characteristics. Table B.26 lists the design parameters used in establishing the dependable capacity at Watana. (i) Installed Capacity A computer simulation of reservoir operation over 32 years of hydrological record was used to predict firm (dependable) and ave·rage energy avail able from Watana and Devil Canyon reservoir~ on a monthly basis. Seven alternative reservoir operating rules were assumed, varying from a maximum power generation scenario which would result in significant impact to dam stream fisheries (Case A) through to a flow that provides guaranteed minimum summer releases which minimize the impact on down-stream fisheries (Case D). For the preliminary design, Case C predicted energies have been used to assess the required plant capacity. The computer simulation gives an estimate of the monthly energy available from each reservoir, but the sizing of the plant capacity must take into account the variation of 2-5 ( .. ) 11, demand load throughout each month on an hourly basis. Load forecast studies have been undertaken to predict the hourly variation of load through each month of the year, and also the growth in peak load (MW) and annual energy demand (GWh) through to the end of th eplanning horizon, 2010. The economic analysis for the proposed development assumes that the average energy from each reservoir is available every year. The hydrological record, however, is such that this average energy is available only from a series of wetter and drier years. In order to utilize the average energy, capacity must be available to generate the energy available in the wet years up to the maximum requirement dictated by the system energy demand, less any energy available from other committed hydro plant. Watana has been designed to operate as a pedking station, if required. Tables 8.27 and 8.28 show the estimated maximum capacity required in the peak demand month (December) at Watana to fully utilize the energy available from the flows of record. If no thermal energy is needed (i.e., in wetter years), the maximum requirement is controlled only by the shape of the demand curve. If thermal energy is required (in average to dry years), the maximum capacity required at Watana will depend on whether the thermal energy is provided by high merit order plant at base load (Option 1, Table 8.27); or by low merit order peaking plant (Option, Table 8.28). On the basis of this evaluation, the ultimate power genera- tion capabi 1 ity at Watana was selected as 1020 ~IW for design purposes to allow a margin for hydro f)inning reserve and standby for forced outage. This installation also provides a margin in the event that the load growth exceeds the medium load forecast. Unit Capacity Selection of the unit size for a given total capacity is a compromise between the initial least cost solution, gener- ally i.1vo1 ving a scheme with a smaller number of 1 arge capacity units, and the improved plant efficiency and s~curity of operation provided by a larger number of 5maller capacity units. Other factors include the size of each unit as a proportion of the total system load and the minimum anticipated 1oad on the station. Any requirement for a minimum downstream flow would also affect the selec- tion. Growth of the actual load demand is also a signifi~ cant factor, since the installation of units may be phased to match the actual load growth. The number of units and 2-6 • * • I (c) I their individual ratings were determined by the need to deliver the required peak capacity ~n the peak demand month of December at the minimum December reservoir level with the turbine wicket gates fully openn An examination was made of the economic impact on power plant production costs of various combinations of a number of units and rated capacity which would provide the sel- ected totat capacity of 1020 MW. For any given installed capacity, plant efficiency increases as the number of units increases. The assumed capitalized value used in this evaluation was $1.00 per average annual kWh over project life, based on the economic analysis completed for the thermal generation system. Variations in the number of units and capacity will affect the cost of the power intakes, penstocks, powerhouse, and tailrace. The differ- ences in these capital costs were estimated and included in the evaluation. The results of this analysis are presented below. Rated Capitalized Value of Additional Capacity Add it i anal Number of Unit Energy Capital Cost Net Benefit of Units (MW) {$Millions) ( $ Mi 11 ions) {$ Millions) 4 6 8 250 170 40 31 9 125 50 58 -8 It is apparent from this analysis that a six-unit scheme with a net benefit of approximately $9 million is the most economic alternative. This scheme also offers a higher degree of flexibility and security of operation compared to the four-unit alternative, as well as advdntages if unit installation is phased to match actual load growth. The net economic benefit of the six unit scheme is $17 million greater than that of the eight-unit scheme, while at the same time no significant operational or scheduling advan- tages are associated with the eight-unit scheme. A scheme incorporating six units each with a rated capacity of 170 MW, for a total of 1020 MW, has been adopted for all Watana alternatives. Selection of the Spillway Design Flood Normal design practice for projects of this magnitude, together with applicable design regulations, require that the project be capable of passing the Probable Maximum Flood (PMF) routed through the reservoir without endangering the dam. 2-7 • .la ~ j J , . . J 'l td I l ~ ' wl ~... .- In addition to this requirement, the project should have sufficient spillway capacity to safely pass a major flood o·; lesser magnitude than the PMF without damaging the main dam or ancillary structures. The frequency of occurrence of this /lood, known as the sp i 11 way design flood or Standard Project Flood (SPF), is generally selected on the basis of an evaluation of the risks to the project if the spillway design flood is exceeded, compared to the costs of the structures required to safely discharge the flood. For this study, a spillway design flood with a return frequency of 1:10,000 years was selected for Watana. A list of spillway design flood frequencies and magnitudes for several major projects is presented below. Spi 11 \vay Spillway Design Flood Basin Capacity PeaK PMF After Routing Project Frequency Inflow (cfs) (cfs) (cfs)* Mica, Canada PMF 250,000 250,000 150,000 Churchill Falls, Canada 1:10,000 600,000 1,000,000 230,000 New Bullards, USA PMF 226,000 226,000 170,000 Oroville, USA 1:10,000 440,500 711,400 4409500 Guri, Venezuela (final stage) PMF 1,000,000 1,000,000 1,000,000 Itaipu, Brazi 1 PMF 2,195,000 2,195,000 2,105,000 Sayano, USSR 1:10,000 480,000 N/A 680,000 *A11 spillways except Sayano have capacity to pass PMF with surcharge. The flood frequency aralysis produced the following values: Flood Probable Maximum Spillway Design Frequency 1:10,000 years Inflow Peak 326,000 cfs 156,000 cfs Additional capacity required to pass the PMF will be provided by an emergency spillway consisting of a fuse plug and rock channel on the right bank. (d) Main Dam Alternatives This section describes the alternative types of dams considered at the Watana site and the basis for the selected alternative. 2-8 I I I I I I I I I I I t t l (i) Comparison of Embankment and Concrete Type Dams The selection between an embankment type or a concrete type dam is usually based on the configuration of the valley, the condition of the foundation rock, depth of the over- burden, and the relative availability of construction materials. Previous studies by the COE envisaged an embankment dam at Watana. Initial studies completed as part of this current evaluation included comparison of an :~arthfi 11 dam with a concrete arch dam at the \~atana site. An arrangement for a concrete arch dam alternative at Watana is presented in Figure B.20. The results of this analysis indicated that the cost of the embankment dam was somewhat lower than the arch dam, even though the concrete cost rates used were significantly lower than those used for the Devil Canyon Dam. This preliminary evaluation did not indicate any overall cost savings in the project in spite of some savings in the earthworks and concrete struc- tures for the concrete dam layout. A review of the overall construction schedule indicated a minimal savings in time for the concrete dam project. Based on the above and the likelihood that the cost of the arch dam would increase relative to that of the embankment dam, the arch dam alternative was eliminated from further consideration. (ii) Concrete-face Rockfill Type Dam The selection of a concrete-face rock fill da,n at Watana would appear to offer economic and schedule advantages when compared to a conventional impervious-core rock fill dam. For example, one of the primary areas of concern with the earth-core rock fill dam, is the control of water content for the core material and the available construction period during each summer. The core material will have to be protected against frost penetration at the end of each season and the area cleared and prepared to receive new material after each winter. On the oth~: hand, rock fill materials can be worked almost year-round and the quarrying and placing/compacting operations are not affected by rain and only marginally by winter weather. The concrete face rock fill dam would also require less foundation preparation, since the critical foundation contact area is much less than that for the impervious- core/rock foundation contact. The side slopes for faced rock fill could probably be of the order of 1.5:H to l:V or steeper as compared to the 2.5 and 2.0:H to l:V for the earth-core rock fill .. This would allow greater flexibility for layout of the other facilities; in particular, the 2-9 .. .. ., ·11 ... •.·.· :·I I I I! I Ji L the upstream and downstream porta 1 s of the diversion tunnels and the tailrace tunnel portals. The diversion tunnels could b0 shorter, giving further savings in cost and schedule. However, the height of the Watana dam as currently proposed is 885 feet, some 70 percent higher than the highest concrete face-rock fill dam built to date (the 525-foot high Areia dam in Brazil completed in 1980). A review of concrete face rock fill dams indicates that increases in height have been typically in the range of 20 percent; for example, Paradela-370 feet completed in 1955, Alto Anchicaya-460 feet completed in 1974, Areia -525 feet completed in 1980. Although recent compacted rock fill dams have generally performed well and a rock fill dam is inherently stable even with severe leakage through the face, a one-step increase in height of 70 percent over existing structures is well beyond percedent. In addition to the height of the dam, other factors which are beyond precedent inc 1 ude the seismic and climatic conditions at Susitna. It has been stated that concrete face rock fill dams are well able to resist earthquake forces and it is admitted that they are very stable structures in themselves. However, movement of rock leading to failure of the face slab near the base of the dam could result in excessive leakage through the dam. To correct such an occurrence would require lowering the water level in the reservoir which would take many year·s and involve severe economic penalties from loss of generating capacity. No concrete face rock fill dam has yet been built in an arctic environment. The drawdown at Watana is in excess of 100 feet and the upper section of the face slab will be subjected to severe freeze/thaw cycles. Although the faced rock fill dam appears to offer schedule advantages, the overall gain in impoundment schedule would not be so significant. With the earth-core rock fill dam, impoundment can be allowed as the dam is constructed. This is not the case for a concrete faced rock fill since the concrete face slab is normally not cJnstructed until all rock fill has been placed and construction settlement taken place. The slab is then poured in continuous strips from the foundation to the crest. Most recent high faced rock fill dams also incorporate an impervious earth fill cover over the lower section to minimize the risk of excessive leakage through zones which, because of their depth below normal water level, are difficult to repair. Such a zone 2-10 I I I I I 1 t. at Watana might cover the lower 200 to 300 feet of the slab and require considerable volumes of impervious fill, none of which could be placed until all other construction work had been completed. This work would be on the critical path with respect to impoundment and, at the same time, be subject to interference by wet weather. The two types of dam were not casted in detail because cost was not consid~ed to be a controlling factor. It is of interest to note, however, that similar alternatives were estimated for the LG 2 project in northern Quebec and the concrete face alternative was estimated to be about 5 percent cheaper. However, the managers, on the · recommedation of their consultants, decided against the use of a concrete face rock fill for the required height of 500 feet in that environment. In summary, a concrete face rock fill dam at Wat an a is not considered appropr i ate as a firm recommendation for the feasibility stage of development of the Susitna project because of: the 70 percent increase in height over precedent; and the possible impacts of high seismicity and climatic conditions. (iii) Selection of Dam Type Selection of the configuration of the embankment dam cross-section was undertaken within the context of the following basic considerations: -The availability of suitable construction materials within economic haul distance, particularly cm'"e materia 1; -The requirement that the dam be capable of withstanding the effects of a significant earthquake shock (2) as well as well as the static loads imposed by the reservoir and its own weight; -The relatively limited construction season available for p 1 acement of compacted fi 11 materials. The main dam would consist of a compacted core protected by fine and coarse filter zones on both the upstream and down- 2-11 ··~ ~.:. il 1 rl !I I I I I ' .. t ' I L~ stream slopes of the core. The upstream and downstream outer supporting fill zones would contain relatively free draining compacted gravel or rockfill, providing stability to the overall embankment structure. The location and inclination of the core is fundamental to the design of the embankment~ Two basic alternatives exist in this regard: - A vertical core located centrally within the dam; and -An inclined core with both faces sloping upstream. A central vertical core was chosen for the embankment based on a review of precedent design and the nature of the availabl~ impervious material. The exploration program undertaken during 1980-81 indicated that adequate quantities of materials suitable for dam con- struction were located within reasonable haul distance from the site. The well-graded silty sand material is consid- ered the most promising source of impervious fill. Compac- tion tests indicate a natural moisture content slightly on the wet side of optimum moisture content, so that control of moisture content will be critical in achieving a dense core with high shear strength. Potential sources for the upstream and downstream shells include either river gravel from borrow areas along the Susitna River or compacted rockfill from quarries or exca- vations for spillways. During the intermediate review process, the upstream slope of the dam was flattened from 2.5H:lV used during the ini- tial review to 2.75H:1V. This slope was based on a con- servative estimate of the effective shear strength p~ra­ meters of the available construction materials, as well as a conservative allowance in the design for the effects of earthqu~ke loadings on the dam. During the final review stage, the exterior upstream slope of the dam was steepened from 2.75H:lV to 2.4H:1V, reflect- ing the results of the preliminary static and dynamic design analyses being undertaken at the same time as the general arrangement studies. As part of the final review, the vo 1 ume of the dam with an upstream s 1 ope of 2. 4H: 1 V was computed for four alternative dam axes. The location of these alternative axes are shown on Figure 8.21. The dam volume associated with each of the four alternative axes is listed below: 2-12 .· ·• 11 !:j tl I I I I I I I "' (e) Alternative Axis Number 1 2 3 4 Total Volume (million yd3) 69.2 7L.7 69.3 71.9 A section with a 2.4H:1V upstream slope and a 2H:1V down- stream slope located on alternative axis .number 3 was used for the final review of alternative schemes. Diversion Scheme Alternatives The topography of the site generally dictates that diversion of the river during construction be accomplished using diversion tun- nels with upstream and downstream cofferdams protecting the main construction area. The configuration of the river in the vicinity of the site favors location of the diversion tunnels on the north bank, since the tunnel length for a tunnel on the south bank would be approximate- ly 2,000 feet greater. In addition, rock conditions on the north bank are more favorable for tunneling and excavation of intake and outlet portals. (i) Design Flood for Diversion The recurrence interval of the design flood for diversion is generally established based on the characteristics of the flow regime of the river, the length of the construc- tion period for which diversion is required and the pro- bable consequences of overtopping of the cofferdams. Design criteria and experience from other projects similar in scope and nature have been used in selecting the diver- sion design flood. At Watana damage to the partially completed dam could be significant, or more importantly would probably result in at least a one-year delay in the completion schedule. A preliminary evaluation of the construction schedule indicates that the diversion scheme would be required for 4 or 5 years until the dam is of sufficient height to permit initial filling of the reservoir. A design flood with a return frequency of 1:50 years was selected based on experience and practice with other major hydroelectric projects. This approximates a 90 percent probability that the cofferdam will not be overtopped during the 5-year construction period. The diversion design flood together with average flow characteristics of the river significant to diversion are presented below: 2-13 ... I I r ! J . J 'I ,, J J . ~· tl I .. I I I I I l I. [ L Average annual flow Maximum average monthly flow Minimum average monthly flow Design flood inflow (1:50 years) ( i i) Cofferdams 7,990 cfs 23,100 cfs (June) 890 cfs (March) 87,000 cfs For the purposes of establishing the overall general arrangement of the project and for subsequent diversion optimization studies, the upstream cofferdam section adopted comprises an initial closure dam structure approxi- mately 30 feet high placed in the weto (iii) Diversion Tunnels Concrete-lined tunnels and unlined rock tunnels were com- pared. Preliminary hydraulic studies indicated that the design flood routed through the diversion scheme would re- sult in a design discharge of approximately 80,500 cfs. For concrete-lined tunnels, design velocities of the order of 50 ft/s have been used in several projects. For unlined tunnels, maximum design velocities ranging from 10 ft/s in good quality rock to 4 ft/s in less competent material are typical. Thus, the volume of material to be excavated using an unlined tunnel would be at least 5 times that for a lined tunnel. The reliability of an unlined tunnel is more dependent on rock conditions than is a lined tunnel, particularly given the extended period during which the diversion scheme is required to operate. Based on these considerations, given a considerably higher cost, together with the somewhat questionable feasibility of four unlined tunnels with diameters approaching 50 feet in this type of rock, the unlined tunnels have been eliminated. The following alternative lined tunnel schemes were examined as part of this analysis: -Pressure tunnel with a free out 1 et; -Pressure tunnel with a submerged outlet; and -Free flow tunnel. (iv) Emergency Release Facilities The emergency release facilities influenced the number, type, and arrangement of the diversion tunnels selected for the final scheme. At an early stage of the study, it was established that some form of low level release facility was required to 2-14 ... .. I I I I I I I I f f [ .,. meet instream flow requirements during filling of the reservior, and to permit lowering of the reservoir in the event of an extreme emergency. The most economical alternative available would involve converting one of the diversion tunnels to permanent use as a low level outlet facility. Since it would be necessary to maintain the diversion scheme in service during construction of the emergency facilities outlet works, two or more diversion tunnels would be required. The use of two diversion tunnels also provides an additional measure of security to the diversion scheme in case of the loss of service of one tunnel. The low level release facilities will be operated for approximately three years during filling of the reservoir. Discharge at high heads usually requires some form of energy dissipation prior to returning the flow to the river. Given the space restrictions imposed by the size of the diversion tunnel, it was decided to utilize a double expa~sion system constructed within the upper tunnel. (v) Optimization of Diversion Scheme Given the considerations described above relative to design flows, cofferdam configuration, and alternative types of tunnels, an economic study was undertaken to determine the optimum combination of upstream cofferdam height and tunnel diameter. Capital costs were developed for three heights of upstream cofferdam embankment with a 30-foot-wide crest and exterior slopes of 2H:1V. A freeboard allowance of 5 feet for set- tlement and wave runup and 10 feet for the effects of down- stream ice jamming on tailwater elevations was adopted. Capital costs for the 4,700 foot long tunnel alternatives included allowances for excavation, concrete liner, rock bolts, and steel supports. Costs were also developed for the upstream and downstream portals, including excavation and support. The cost of intake gate structures and asso- ciated gates was determined not to vary significantly with tunnel diameter and was excluded from the analysis. Curves of headwater elevation versus tunnel diameter for the various tunnel alternatives with submerged and free outlets are presented in Figure 8.22. The relationship between capital cost and crest elevation for the upstream cofferdam is shown in Figure 8.23. The capital cost for various tunnel diameters with free and submerged outlets is given in Figure 6.24. 2-15 ... • J:,··· ' • 'l·f:-.. ·· l \ - The results of the optimization study ars presented in Figure 8.25 and indicate the fv.llowing optimum solutions for each alternative. Diameter Cofferdam Crest Type of Tunnel (feet) El ev at ion ( ft) Tot a 1 Cost ( $ ) Two pressure tunnels 30 1595 66,000,000 Two free flow tunnels 32.5 1580 68,000,000 Two free flow tunnels 35 1555 69,000,000 The cost studies·indicate that a relatively small cost dif- ferential (4 to 5 percent) separates the various alterna- tives for tunnel diameter from 30 to 35 feet. (vi) Selected Diversion Scheme An important consideration at this point is ease of coffer- dam closure. For the pressure tunnel scheme, the invert of the tunnel entrance is below riverbed elevat·ion, and once the tunnel is complete diversion can be accomplished with a closure dam section approximately 10 feet high. The free flow tunnel scheme, however, requires a tunnel invert approximately 30 feet above the riverbed level, and diver- sion would involve an end-dumped closure section 50 feet high. The velocities of flows which would overtop the cof- ferdam before the water levels were raised to reach the tunnel invert level would be prohibitively higher, resulting in complete erosion of the cofferdam, and hence the dual free flow tunnel scheme was dropped from consideration. Based on the preceeding considerations, a combination of one pressure tunnel and one free flow tunnel (or pressure tunnel with free outlet) was adopted. This will permit initial diversion to be made using the lower pressure.tun- nel, thereby simplifying the critical closure operation and avoiding potentially serious delays in the schedule. Two alternatives were re-evaluated as follows: Tunnel Diameter (feet) 30 35 Upstream Cofferdam· Crest Elevation Approximate Height (feet) (feet) 1595 1555 2-16 150 110 ; l J J J ' j j J J J J J J J More detailed layout studies indicated that the higher cofferdam associated with the 30 foot diameter tunnel alternative would require locating the inlet portal further upstream into 11 The Fins 11 shear zone. Si nee good rock conditions for portal construction are essential and the 35 foot diameter tun~el alternative would permit a portal location downstream of 11 The Fins 11 , this latter alternative was adopted. As noted in (v), the overall cost difference was not significant in the range of tunnel diameters con- sidered, and the scheme incorporating two 35 foot diameter tunnels with an upstream cofferdam crest elevation of 1555 was incorporated as part of the selected general arrange-ment. (f) Spillway Facilities Alternatives As discussed in subsection (c) above, the project has been designed to safely pass floods with the following return fre-quencies: Flood Inflow Peak (cfs) --...:.,_ Total Spillway Discharge (cfs} Spillway Design Probable Maximum Frequency 1:10,000 years 156,000 326,000 119,000 150,000 Discharge of the spillway design flood will require a gated ser- vice spillway on either the left or right bank. Three basic al- ternative spillway types were examined: -Chute spillway with flip bucket; -Chute spillway with stilling basin; and -Cascade spillway. Consideration was also given to combinations of these alternatives with or without supplemental facilities such as valved tunnels and an emergency spillway fuse plug for handling the PMF discharge. Clearly, the selected spillway alternatives wi"ll greatly influence and be influenced by the project general arrangement. (i) Energy Dissipation The two chute spillway alternatives considered achieve effective energy dissipation either by means of a flip bucket which would direct the spillway discharge in the form of a free-fall jet into a plunge pool well downstream from the dam or a stilling bas in at the end of the chute which would dissipate energy in a hydraulic jump. The cascade type spillway would limit the free fall height of 2-17 .. .. I I I I I I I I~ I I I I I I l l (ii) the discharge by utilizing a series of 20 to 50 foot steps down to river level, with energy dissipation at each step. All spillway alternatives were assumed to incorporate a concrete agee type control section controlled by fixed roller vertical lift gates. Chute spillway sections were assumed to be concrete-lined, with ample provision for air entrainment in the chute to prevent cavitation erosion, and with pressure relief drains and rock anchors in the foundation. Environmental Mit i gat i o_fl During development of the general arrangements for both the Watana and Devil Canyon dams, a restriction was imposed on the amount of excess dissolved nitrogen permitted in the spillway discharges. Supersaturation occurs when aerated flows are subjected to pressures greater than 30 to 40 feet of head which forces excess nitrogen into solution. This occurs when water is subjected to the high pressures that occur in deep plunge pools or at large hydraulic jumps. The eY.cess nitrogen would not be dissipated within the downs·:ream Devil Canyon reservoir and a buildup of nitrogen concentration could occur throughout the body of water. It would even~~ally be discharged downstream from Devil Canyon with harmful effects on the fish population. On the basis of an evaluation of the related impacts and discussions with interested federal and state agencies, spillway facil- ities were designed to limit discharge3 of water from either Watana or Devil Canyon that may become supersat- urated with nitrogen to a recurrence period of not less than 1:50 years. (g) Power Facilities Alternative Selection of the optimum power plant development involved consid- eration of the following: -Location, type and size of the power plant; -Geotechnical considerations; -~umber, type, size and setting of generating units; -Arrangement of intake and water passages; and -Environmental constraints. (i) Comparison of Surface and Underground Powerhouse Studies were carried out to compare the construction costs of a surface powerhouse and of an underground powerhouse at Watana. These studies were undertaken on the basis of pre- liminary conceptual layouts assuming six units and a total 2-18 • " • .J .J . l l J . J J j .J J J J J .. ~ · . .. ...... i ' .. ·· . • installed capacity of 1020 MW. The comparative cost estimates for powerhouse civil works and electrical and mechanical equipment (excluding common items) indicated an advantage in favor of the underground powerhouse of $16,300,000. The additional cost for the surface power- house arrangement is primarily associated with the longer penstocks and the steel linings required . The underground powerhouse arrangement is also better suited to the severe winter conditions in Alaska, is less affected by river flood flows in summer, and is aesthet- ically less obtrusive. This arrangement has therefore been adopted for further development . (ii) Comparison of Alternative Locations Preliminary studies were undertaken during the development of conceptual project 1 ayouts at Watana to investigate both right and left bank locations for power facilities. The configuration of the site is such that south bank locations required longer pP.nstock and/or tailrace tunnels and were therefore more expensive. The location on the south bank was further rejected because of indications that the underground facilities would be located in relatively poor quality rock. The underground powerhouse was therefore located on the north bank such that the major openings lay between the two major shear features (11 The Fins 11 and the "Fingerbuster"). (iii) Underground Openings Because no construction adits or extensive drilling in the powerhouse and tunnel locations have been completed, it has been assumed that full concrete-lining of the penstocks and tailrace tunnels would be required. This assumption is conservative and is for preliminary design only; in prac- tice, a large pt~oportion of the tailrace tunnels would pro- bably be unlined, depending on the actual rock quality en-countered. The minimum center-to-center ~pacing of rock tunnels and caverns has been assumed for layout studies to be 2.5 times the width or diameter of the larger excavation. (iv) Selection of Turbines The selection of turbine type is governed by the available head and flow. For the design head and specific speed, Francis type turbines have been selecteJ. Francis turbines 2-19 ( .. ' j J j j j j (v) have a reasonably flat load-efficiency curve over a range from about 50 percent to 115 percent of rated output with peak efficiency of about 92 percent. The number and rating of individual units is discussed in detail in subsection (b) above. The final selected arrangement comprises six units producing 170 MW each, rated at minimum reservoir level (from reservoir simulat·fon studies) in the peak demand month (December) at full gate. The unit output at best efficiency and a rated head c~ 580 feet is 181 ~1W. Transformers The selection of transformer type, size, location and step-up ratir1g is summarized below: -Single phase transformers are required because of trans- port limitations on Alaskan roads and railways; -Direct transformdtion from 15 kV to 345 kV is preferred for overall system transient stability; -An underground transformer gallery has been selected for minimum total cost of transformers, cables, bus, and transformer losses; and -A grouped arrangement of three sets of three single-phase transformers for each set of two units has been selected (a total of nine transformers) to reduce the physical size of the transformer gallery and to provide a trans- former spacing comparable with the unit spacing. (vi) fower Intake and Water Passages The power intake and approach channel are significant items in the cost of the overall power facilities arrangement. The size of the intake is controlled by the number and min- imum spacing between the penstocks, which in turn is dic- tated by geotechnical considerations. The preferred penstock arrangement comprises six individual penstocks, one for each turbine. With this arrangement, no inlet valve is required in the powerhouse since turbine dewatering can oe performed by closing the control gate at the intake and draining the penstocks and scroll ca~e through a valved bypass to the tailrace. An alternative arrangement with three penstocks was considered in detail tc assess any possible advantages. This scheme would require a bifurcation and two inlet valves on each penstock 2-20 • . . . ~ .. • ,. , . • -..A' 0 • ,. 't ~~ ... ~• o• /t '( ~ •· ... • ~;' • ~ .~I • ~ • : rf ' ~ ~ . ~ • • • • ~> ' ,.. ' " -r{l· ; 1 i ~ j j ] !tern and extra space in the powerhouse to accommodate the inlet valves. Estimates of relative cost differences are sum- marized below: Cost Difference ($ x 106) 6 Penstocks 3 Penstocks Intake Penstocks Bifurcations Valves Powerhouse Base Case 0 0 0 0 .,20.0 -3.0 + 3.0 + 4.0 + 8.0 + 6.0 Capitalized Value of Extra Head Loss 0 Total 0 -2.0 Despite a marginal saving of $2 million (or less than 2 percent in a total estimated cost of $120 mill ion) in favor of three penstocks~ the arrangement of six individual pen- stocks has been retained. This arrangement provides im- proved flexibility and security of operation. The preliminary design of the power facilities involves two tailrace tunnels leading from a common surge chamber. An alternative arrangement with a single tailrace tunnel. was also considered~ but no significant cost saving was apparent. Optimization studies on all water passages were carried out to determine the minimum total cost of initial construction plus the capitalized value of anticipated energy losses caused by conduit friction~ bends and changes of section. For the penstock optimization, the construction costs of the intake and approach channel were included as a function of the pensto~k diameter and spacing. Similarly, 1n the optimization studies for the tailrace tunnels the costs of the surge chamber were included as a function of tailrace tunnel diameter. (vii) Environmental Constraints Apart from the potential nitrogen supersaturation problem discussed, the major environmental constraints on the design of the power facilities are: -Contra} of downstream river temperatures; and -Control of downstreem flows. The intake design has been modified to enable power plant flows to be drawn from the reservoir at four different levels throughout the anticipated range of reservoir 2-21 .. ) I I I I I l L l drawdown for energy production in order to control the downstream river temperatures within acceptable limits. Minimum flows at Gold Creek during the critical summer months have been studied to mitigate the project impacts on salmon spawning downstream cf Devil Canyon. These minimum flows represent a constraint on the reservoir operation and influence the computation of average and firm energy pro- duced by the Susitna development. The Watana development will be operated as a daily peaking plant for load following. The actual extent of daily peak- ing will be dictated by unit availability, unit size, sys- tem demand, system stability, generating costs, etc. 2.3 -Selection of Watana General Arrangement Preliminary alternative arrangements of the Watana Project were devel- oped ~td subjected to a series of review and screening processes. The layouts selected from each screening prQcess were developed in greater detail prior to the next review and, where necessary, additional lay- outs were prepared combining the features of two or more of the altern- at~ves. Assumptions and criteria were evaluated ot each stage and add- itional data incorporated as necessary. The selection process followed the general selection methodoiogy established for the Susitna project and is outlined below. (a) Selection Methodology The determination of the project general arrangement at Watana was undertaken in three distinct review stages: preliminary, inter- mediate, and final. {i) Preliminary ~.~view (completed early in 1981) This comprised four steps: -Step 1: Assemble available data; Determine design criteria; and Establish evaluation criteria. -Step 2: -Step 3: Develo~ preliminary layouts and design criteria based on the above data including all plausible alternatives for the constituent facilities and structures. Review all layouts on the basis of technical feasibility, readily apparent cost differences, safety, and environmental impact. 2-22 • ~ -.,.._ ..... __ _,....,.,_......, --------.....,.......,......,. ___ ~~~ '" ---~-.::.:: :: .. :.-...::...".· ':,', ~ -~--· I I ~~.· ;i' " f:' l r -Step 4: Select those layouts that can be identified as most favorable, based on the evaluation criteria established in Step 1, and taking into account the preliminary nature of the work at this stage. {ii) Intermediate Review (completed by mid-1981) This involved a series of 5 steps: -Step 1: Review all data, incorporating additional data from other work tasks. Review and expand design criteria to a greater 1 evel of detai 1. Review evaluation criteria and modify, if neces- sary. -Step 2: Revise selected layouts on basis of the revised criteria and additional data. Prepare plans and principal sections of layouts. -Step 3: Prepare quantity estimates for major structures based on drawings prepared under Step 2. Develop a preliminary construction schedule to evaluate whether or not the selected layout will allow completion of the project within there- quired time frame. Prepare a preliminary contractor's type estimate to determine the overall cost of each scheme. -Step 4: Review all layouts on the basis of technical feasibil~ty~ cost impact of possibie unknown conditions and uncertainty of assumptions~ safe- ty, and environmental impact. -Step 5: Select the two most favorable layouts based on the evaluation criteria determined under Step 1. (iii) Final Review (completed early in 1982) -Step 1: Assemble and review any additional data from other wm·k tasks. Revise design criteria in accordance with addi- tional available data. Finalize overall evaluation criteria. 2-23 • .. 1 I '): i u l [ t -Step 2: Revise or further develop the two layouts on the basis of input from Step 1 and determine overall dimensions of structures, water passages, gates, and other key items. -Step 3: Prepare quantity take-offs for all major struc- tureso Review cost components within a preliminary con- tractor's type estimate using the most recent data and criteria, and develop a construction schedule. Determine overall direct cost of schemes. -Step 4: Review all layouts on the basis of practicabil- ity, technical feasibility, cost, impact of pos- sible unknown conditions, safety, and environ- mental impact. -Step 5: Select the final layout on the basis of the evaluation criteria developed under Step 1. (b) Design Data and Criteria (c) (d) As discussed above, the review process included assembling rele- vant design data, establishing preliminary design criteria, and expanding and refining these data during the intermediate and final reviews of the project arrangement. The design data and design criteria which evolved through the final review are pre- sented in Table 8.29. Evaluation Criteria The various layouts were evaluated at each.stage of the review process on the basis of the criteria summarized in Table Bo30. These criteria illustrate the progressively more detailed evaluation process leading to the final selected arrangement. Preliminary Review The development selection studies described in Section 8, Volume 1 of Reference 4, involved comparisons of hydroelectric schemes at a number of sites on the Susitna River. As part of these compari- sons a preliminary conceptual design was developed for Watana in- corporating a double stilling basin type spillway. Eight further layouts were subsequently prepared and examined for the Watana project during this preliminary review process in 2-24 j t l -~ addition to the scheme shown on Figure 8.7. These eight layouts are shown in schematic form on Figure 8.25. Alternative 1 of these layouts was the scheme recommended for further study (1). This section describes the preliminary review undertaken of al- ternative Watana layouts. (i) Basis of Comparison of Alternatives Although it was recognized that provision would have to be made for downstream releases of water during filling of the reservoir and for emergency reservoir drawdown, these fea- tures were not incorporated in these preliminary layouts. These facilities ~~uld either be interconnected with the diversion tunnels or be provided for separately. Since the system selected \vould be similar for all layouts with mini- mal cost differences and little impact on other structures, it was decided to exclude these facilities from overall assessment at this early stage. Ongoing geotechnical explorations had identified the two major shear zones crossing the Susitna River and running roughly parallel in the northwest direction. These zones encl os.e a stretch of watercourse approximately 4500 feet in length. Preliminary evaluation of the existing geological data indicated highly fractured and altered materials within the actual shear zones which would pose serious pro- blem5 for conventional tunneling methods and would be un- suitable for founding of massive concrete structures. The originally proposed dam axis was located between these shear zones, and since no apparent major advantage appeared to be gained from large changes in the dam location, lay- outs generally were kept within the confines of these bounding zones. An earth and rockfi 11 dam was used as the basis for a 11 layouts. The downstream slope of the dam was assumed as 2H:1V in all alternatives and upstream S1upes varying be- tween 2.5H:lV and 2.25H:1V were examined in order to deter~ mine the influence of variance in the dam slope on the con- gestion of the layout. In all preliminary arrangements except the one shown on Figure 8.7, cofferdams were incorporated within the body of the main dam. Floods greater than the routed 1:10,000 year spillway design flood and up to the probable maximum flood were assumed to be passed by surcharging the spillways, except in cases where an unlined cascade or stilling basin type spillway served as the sole discharge facility. In $UCh 2-25 • ' l l ' • ,J it'' ' ' , I ~ instances, under 1 arge surcharges, these spillways would not act as efficient energy dissipaters but would be drowned out, acting as steep open channels with the possi- bility of their total destruction. In order to avoid such an occurrence the design flood for these latter spillways was co~sidered as the routed probable maximum flood. On the basis of information existing at the time of the preliminary review, it appeared that an underground power- house could be located on either side of the river. A sur- face powerhouse on the north bank appeared feasible but was precluded from the south bank by the close proximity of the downstream toe of the dam and the adjacent broad shear zone. Locating the powerhouse further downstrea111 would require tunneling across the shear zone, which would be expensive and would require excavating a talus slope. Furthermore, it was found that a south bank surface powerhouse would either interfere with a south bank spillway or would be directly impacted by discharges from a north bank spillway. (ii) Description of Alternative Double Stilling Basin Scheme The scheme as shown on Figure 8.7 has a dam axis loca- tion similar to that originally proposed by the COE, and a north bank double stilling basin spillway. The spill- way follows the shortest line to the river, avoiding interference with the dam and discharging downstream almost parallel to the flow into the center of the river. A substantial amount of excavation is required for the chute and stilling basins, although most of this material could probably be used in the dam. A large volume of concrete is also required for this type of spillway, resulting in a spillway system that would be very costly. The maximum head dissipated within each stiJling basin is approximately 450 feet. vJithin world experience, cavitation and erosion of the chute and basins should not be a problem if the structures are properly designed. Extensive erosion downstream would not be expected . The diversion follows the shortest route, cutting the bend of the river on the north bank, and has inlet portals as far upstream as possible without having to tunnel through "The Fins 11 • It is possible that the underground powerhouse is in the area of "The Finger-buster~~, but the powerhouse could be located upstream almost as far as the system of drain holes and 2-26 • :w .· 1 i ' ! ~ . , .... galleries just downstream of the main dam grout curtain. -Alternative 1 This alternative, figure B.26, is that recommended for further study (1) and is similar to the layout described above except that the north side of the darn has been rotated clockwise, the axis relocated upstream, and the spillway changed to a chute and flip bucket. The revised dam alignment resulted in a slight reduction in total dam volume compared to the above alternative. A localized downstream curve was introduced in the dam close to the north abutment in order to reduce the length of the spillway. The. alignment of the spillway is almost parallel to the downstream section of the river and it discharges into a pre-excavated plunge pool in the river approximately 800 feet downstream from the flip bucket. This type of spillway should be considerably less costly than one incorporating a stilling basin, provided that excessive pre-excavation of bedrock within the plunge pool area is not required. Careful design of the bucket will be required, however, to prevent excessive erosion downstream causing undermining of the valley sides and/or build up of material downstream which could cause elevation of the tailwater levels. -Alternatives 2 through 20 Alternative 2 consists of a south bank cascade spillway with the main dam axis curving downstream at the abutments. The cascade spillway would require an extremely large volume of rock excavation but it is probable that most of this material, with careful scheduling, could be used in the dam. The excavation would cross 11 The Fingerbuster" and extensive dental concrete would be required in that area. In the .. upstream portion of the spillway, velocities would be relatively high because of the narrow configuration of the channel, and erosion could take place ~n this area in proximity to the dam. The discharge from the spillway enters the river perpendicular to the general flow but velocities would be relatively low and should not cause substantial erosion problems. The powerhouse is in the most suitable location for a surface alternative where the bedrock is close to the surface and the overall rock slope is approximately 2H:1V. 2-27 .. 1.; .1~.' ~~ l l l f ti b Alternative 2A is similar to Alternative 2 except that the upper end of the channel is divided and separate control structures are providede This division would allow the use of one structure or upstream channel while m.:.tintenance or remedi a1 work is being performed on the other. Alternative 2B ·is similar to Alternative 2 except that the cascade spillway is replaced by a double stilling basin type structure. This spillway is somewhat longer than the similar type of structure on the north bank in the alternative described above. However, the slope of the ground is less than the rather steep north bank and may be easier to construct, a factor which may partly mitigate the cost of the longer structure. The dis- charge is at a sharp angle to the river and more concen- trated than the cascade, which could cause erosion of the opposite bank. Alternative 2C is a derivative of 28 with a similar arrangement, except that the double stilling basin spillway is reduced in size and augmented by an addi- tional emergency spillway in the form of an inclined, unlined rock channel. Under this arrangement the con- crete spillway acts as the main spillway, passing the 1:10,000 year design flood with greater flows passed down the unlined channel which is closed at its upstream end by an erodible fuse plug. The problems of erosion of the opposite bank still remain, although these could be overcome by excavation and/or slope protection. Erosion of the chute would be extreme for significant flows, although it is highly unlikely that this emerg- ency spillway would ever be used. Alternative 20 replaces the cascade of A1ternative 2 with a lined chute and flip bucket. The comments rela- tive to the flip bucket are the same as for Alternative 1 except that the south bank location in this instance requires a longer chute, partly offset by lowe~ construction costs because of the flatter slope. ..the flip bucket discharges into the river at an angle which may cause erosion of L-he opposite bank. The underground powerhouse is located on the north bank, an a~rrangement which provides an overall reduction of the length of the water passages. -Alternative 3 This arrangement has a dam axis location slightly upstream from Alternative 2, but retains the downstream 2-28 ·~ j l l t t curve at the abutments. The main spillway is an unlined rock cascade on the south bank which passes the design flood. Discharges beyond the 1:10,000 year flood would be discharged through the auxiliary concrete-lined chute and flip bucket spillway on the north bank~ A gated control structure is provided for this auxiliary spillway which gives it the flexibility to be used as a backup if maintenance should be required on the main spillway. Erosion of the cascade may be a problem, as mentioned previously, but erosion downstream should be a less important consideration because of the low unit discharge and the infrequent operation of the spillway .. The diver~1on tunnels are situated in the north abutment, as with previous arrangements, and are of similar cost for all these alternatives. -Alternative 4 This alternative involves rotating the axis of the main dam so that the south abutment is relocated approximately 1000 feet downstream from its Alternative 2 location. The relocation results in a reduction in the overall dam quantities but would require siting the impervious core of the dam directly over the "Fingerbuster" shear zone at maximum dam height. The south bank spillway, consisting of chute and flip bucket, is reduced in 1 ength compared to other south bank locations, as are the power facility water passages. The diversion tunnels are situated on the south bank; there is no advantage to a north bank location, since the tunnels are of similar length owing to the overall downstream relocation of the dam~ Spillways and power faci1ities would also be lengthened by a north bank location with this dam configuratton. -Selection of Sche~es for Further Study A basic consideration during design development was that the main dam core should not cross the major shear zones because of the obvious problems with treatment of the foundation. Accordingly, there is very little scope for realigning the main dam apart from a slight rotation. to place it more at right angles to the river. Location of the spillway on the north bank results in a shorter distance to the river and allows discharges almost parallel 4o the general direction of river flow4 The double stilling basin arrangement would be extremely expensive, particularly if it must be designed to pass the probable maximum flood. An alternative such as 2C 2-29 .. • I ~ l l would reduce the magnitude of design flood to be passed by the spillway but would only ~e acceptable if an emergen·cy spillway with a high degree of operational predictability could be constructed. A flip bucket spillway on the north bank, discharging directly down the river, would appear to be an economic arrangement~ although some scour might occur in the plunge pool area. A cascade spillway on the south bank could be an acceptable solution providing most of the excavated material could be used in the dam, and adequate rock conditions exist. The length of diversion tunnels can be decreased if they are located on the north bank. In addition, the tunnels would be accessible by a preliminary access road from the north, which is the most likely route. This loca- tion wo u 1 d a 1 so avoid the area of 11 Th e Fi ngerbuster ;• and the steep cliffs which would be encountered on the south side close to the downstream dam toe. The underground configuration assumed for the powerhouse in these preliminary studies allows for location on either side of the river with a minimum of interference with the surface structures. Four of the preceding layouts, or variations of them, were selected for further study: . A variation of the double stilling basin scheme, but with a single stilling basin main spillway on the north bank, a rock channel and fuse plug emergency spillway, a south bank underground powerhouse and a north bank diversion scheme; . Alternative 1 with a north bank flip bucket spillway, an underground powerhouse on the south bank, and north bank diversiG;I; . A variation of Alternative 2 with a reduced capacity main spillway and a north bank rock channel with a fuse plug serving as an emergency spillway; and . Alternative 4 with a south bank rock cascade spillway~ a north bank underground powerhouse, and a north bank diversion. (e) Intermediate Review For the intermediate review process, the four schemes selected as a result of the preliminary review were examined in more detail 2-30 • .. r " j 1 n. ~ L and modified. A description of each of the schemes is given below and shown on Figures 8.27 through B.32. The general locations of the upstream and downstream shear zones shown on these p 1 ates are approximate and have been refined on the basis of subsequent field investigations for the proposed project. (i) Description of Alternative Schemes The four schemes are shown on Figures 8.27 through B.32. -Scheme WP1 (Figure 8.27) This scheme is a refinement of Alternative 1. The up- stream slope of the dam is flattened from 2.5:1 to 2.75:1. This conservative approach was adopted to pro- vide an assessment of the possible impacts on project layout of conceivable measures which may prove necessary in dealing with severe earthquake design conditions. Uncertainty with regard to the nature of river alluvium also led to the location of the cofferdams outside the limits of the main dam embankment. As a result of these conditions, the intake portals of the diversion tunnels on the north bank are also moved upstream from 11 The Fins 11 • A chute spillway with a flip bucket is located on the north bank. The underground powerhouse is located on the south bank. -Scheme WP2 (Figures 8.29 and 8.30) This scheme is derived from the double stilling basin layout. The main dam and diversion facilities are sim- ilar to Scheme WPl except that the downstream cofferdam is relocated further downstream from the spillway outlet and the diversion tunnels are correspondingly extended. The main spillway is located on the north bank, but the two stilling basins of the preliminary DSR scheme are combined into a single stilling basin at the river level. An emergency spiilway is also located on the 'north bank and consists of a channel excavated in rock, discharging downstream from the area of the relict channel. The channel is closed at its upstream end by a compacted earthfill fuse plug and is capable of dis- charging the flow differential between the probable maximum flood and the 1:10,000-year design flood of the main spillway. The underground powerhouse is located on the south bank. 2-31 .. J J f J 1J'' I ·~ ,. J t l l -Scheme WP3 (Figures 8.28 and 8.29) This scheme is similar to Scheme WPl in all respects except that an emergency spillway is added consisting of north bank rock channel and fuse plug. -Scheme WP4 (Figures 8.31 and 8.32) The dam location and geometry for Scheme WP4 are similar to that for the other schemes. The diversion is on the north bank and discharges downstream from the powerhouse tailrace outlet. A rock cascade spillway is located on the south bank and is served by two separate control structure_s with downstream stilling basins. The underground powerhouse is located on the north banko (ii) Comparison of Schemes The main dam is in the same location and has the same con- figuration for each of the four layouts considered. The coffardams have been located outside the limits of the main dam in order to allow more extensive excavation of the alluvial material and to ensure a sound rock foundation beneath the complete a.rea of the dam. The overall design of the dam is conservative, and it was recognized during the evaluation that savings in both fill and excavation costs can probably be made after more detailed study. The diversion tunnels are located on the north bank. The upstream flattening of the dam slope necessitates the loca- tion of the diversion inlets upstream from "The Fins" shear zone which would require extensive excavation and support where the tunnels pass through this extre~ely poor rock zone and could cause delays in the construction schedule. A low-lying area exists on the north bank in the area of the relict channel and requires approximately a 50-foot high saddle dam for closure, given the reservoir operating level assumed for the comparison study. However, the fin- ally selected reservoir operating level will require only a nominal freeboard structure at this location. A summary of capital cost estimates for the four alterna·" tive schemes is given in Table 8n3l. The results of this intermediate analysis indicate that the chute spil1way with flip bucket (Scheme WPl) is the least costly spillway alternative. The scheme has the additional advantage of relatively simple operating characteristics. The control structure 2-32 ,. • \U,, ! \.··. j ~ u ., ~ ~ ' ~ u, ~-~ ( i i i ) ~' ~. t:,1 ~ t L l\ i. ''. ·--..--.~·-·" ___ ,..,.._"_,.,..,~~·~····-·---·~-----~~· --~·-·---~__,~.-----~--~ .. ~~H·~ -~--·-...._ _ _,_,_.;.,_._c~·-~---------*·--- has prov1s1on for surcharging to pass the design flood. The probable maximum flood can be passed by additional sur- charging up to the crest level of the dam. In Scheme WP3 a similar spillway is provided, except that the control structure is reduced in size and discharges above the routed design flood are passed through the rock channel emergency spillway. The arrangement in Scheme WPl does not provide a backup facility to the main spillway, so that if repairs caused by excessive plunge pool erosion or damage to the structure itself require removal of the spillway from service for any length of time, no alternative dis- charge facility would be available. The additional spill- way of Scheme WP3 would permit emergency discharge if it were required under extreme circumstances. The stilling basin spillway (Scheme WP2) would reduce the potential for extensive erosion downstream, but high veloc- ities in the lower part of the chute could cause cavitation even with the provision for aeration of the discharge. This type of spillway would be very costly, as can be s-een from Table 8.28. The feasibility of the rock cascade spillway is entirely dependent on the quality of the rock, which dictates the amount of treatment required for the rock surface and also the proportion of the excavated material which can be usea in the dam. For determining the capita 1 cost of Scheme WP4, conservative assumptions were made regarding surface treatment and the portion of material that would have to be wasted. The diversion tunnels are located on the north bank for all alternatives examined in the intermediate review. For Scheme WP2, the downstre~m portals must be located down- stream from the stilling basin, resulting in an increase of approximately 800 feet in the length of the tunnels. The south bank location of the powerhouse requires its placement close to a suspected shear zone, wit:~ the tailrace tunnels passing through this shear zone to reach the river. A longer access tunnel is alsv required, together with an additional 1,000 feet in the length of the tailrace. The south-side location is remote from the main access road? which will probably ~eon the north side of the river, as will the transmission corridor. Selection of Schemes for Further Study Examination of the technical and economic ~spects of Scheme WPl through WP4 indicates there is little scope for adjust- ment of the dam axis owing to the confinement imposed by 2-33 • IJ u I ' i .I u " J J. the upstream and downstream shear zones. In addition, pas- sage of the diversion tunnels through the upstream shear zone could result in significant delays in construction and additional costo Fr01~ a comparison of costs in Table 8.28, it can be seen that the flip bucket type spillway is the most economical, but because of the potential for erosion under extensive operation it fs undesirable to use it as the only discharge facility. A mid-level release will be required for emer- gency drawdown of the reservoir, and use of this release as the first-stage service spillway with the flip bucket as a backup facility would combine flexibility and safety of operation with reasonable cost. The emergency rock ~hannel spillway wc~uld be retained for discharge of flows above the routed 1:10,000-year flood. The stilling ba.sin spillway is very costly and the operat- ing head of 800 feet is beyond precedent experience. Ero- sion downstream should not be a problem but cavitation on the chute could occur. Scheme WP2 was therefore eliminated from further consideration. The cascade spillway was also not favored for techrical and economic reasons. H~wever, this arrangement does have an advantage in that it provides a means of preve~t~ng nitro- gen supersaturation in the downstream discharges from the project which could be harmful to the fish population. A cascade configuration would reduce the dissolved nitrogen content; hence~ this alternative was retained for further evaluation. The capacity of the cascade was reduced and the emergency rock channe 1 spill way was inc 1 uded to take the extreme floods. The results of the intermediate review indicated that the following components should be incorporated into any scheme carried forward for final review: -Two diversion tunnels located on the north bank of the river; ·· An underground powerhouse v.l so located on the north bank; An emergency spillway, compr1s1ng a rock channel ex:a- vated on the north bank and discharging well downstream from the north abutment. The channe1 is sealed by an erodible fuse plug of impervious material designed to fail if overtopped by the reservoir; and 2-34 I I I - A compacted earthfill and rockfill dam situated between the two major shear zones which traverse the project site. As discussed above, two specific alternative methods exist witn respect to routing of the spillway design flood and minimizing the adverse effects of nitrogen supersaturation on the downstream fish population. These alternatives are: - A chute spillway with flip bucket on the north bank to pass the spillway design flood, with a mid-level release system designed to operate fo~ floods with a frequency of up to about 1:50 years; or -A cascade spillway on the south bank. Accordingly, two schemes were developed for further ·eva·lua- tion as part of the final review process. These schemes are described separately in the paragraphs below. (f) Final Review The two schemes considered in the final review process were essen- tially deriva~ions of Schemes WP3_ and WP4. (i) Scheme WP3A (Figure B.33) This scheme is a modified version of Scheme WP3 described above. Because of scheduling and cost considerations, it is extremely important to maintain the diversion tunnels downstream ·from 11 The F·i ns." It i·s a 1 so important to keep the dam axis as far upstream as possible to avoid conges- tion of the downstream structures. For these reasons, the inlet portals to the .... :version tunnels were located in the sound bedrock forming the downstream boundary of "The Fins.11 The up~:ream cofferdam and main dam are maintained in the upstream locations as shown on Figure B.33. As mentioned previously, additional criteria have necessitated modifications in the spillway configuration, and low-level and emergency drawdown outlets have been introduced. The main modifications to the scheme are as follows: -Main Dam Continuing preliminary design studies and review of world practice suggest that an upstream slope of 2.4H:lV would be dcceptable for the rock shell. Adoption of this slope 2-35 .. .. I I u u I results not only in a reduction in dam fill volume but also in a reduction in the base width of the dam which permits the main project components to be located between the major shear zones. The downstream slope of the dam is retained as 2H:lV. The cofferdams remain outside the limits of the dam in order to allow complete e.xcavation of the riverbed allu-vium. -Diversion In the intermediate review arrangements, diversion tun- nels passed through the broad structure of "The Fins," an intensely sheared area of breccia, gouge, and infills. Tunneling of this material would be difficult, and might even require excavation in open cut from the surface. High cost would be involved, but more important would be the time taken for construction in this area and the pos- sibility of unexpected delays. For this reason, the inlet portals have been relocated downstream from this zone with the tunnels located closer to the river and crossing the main system of jointing at approximately 45°. This arrangement allows for ~horter tunnels with a more favorable orientation of the inlet and outlet portals with respect to the river flow directions. A separate low-level inlet and concrete-lined tunnel is provided, leading from the reservoir at approximate Ele- vation 1550 to downstream of the diversion plug where it merges with the diversion tunnel close~t to the river. This low-level tunnel is designed to pass flows up to 12,000 cfs during reservoir filling. It would also pass up to 30~000 cfs under 500-foot head to allow emergency draining of the reservoir. Initial closure is made by lowering the gates to the tun- nel located closest to the river and constructing a con- crete closure plug in the tunnel at the location of the grout curtain underlying the core of the main dam. On completion of the plug, the low-level release is opened and controlled discharges are passed downstream. The closure gates within the second diversion tunnel portal are then closed and a concrete closure plug constructed in line with the grout curtain. After closure of the gatesl filling of the reservoir would commence. -Outlet Facilities As a provision for drawing down the reservoir in case of emergency, a mid-level release is provided. The intake 2-36 .. I I I 1 to these facilities is located at depth adjacent to the power facilities intake structures. Flows would then be passed downstream r.hrough a concrete-1 ined tunnel, dis- charging beneath tt:e downstream end of the main spillway flip bucket. In order to overcome potential nitrogen supersaturation problems, Scheme WP3A also incorporates ~ system of fixed cone valves at the downstream end of the outlet facilities. The valves were sized to discharge in conjunction with the powerhouse oper·ating at 7000 cfs capacity (flows up to the equivalent routed 50-year flood). Six cone valves are r·equired, located on branches from a steel manifold and protected by individual upstream closure gates. The valves are partly .incorporated into the mass concrete block forming the flip bucket of the main spillway. The rock downstream is protected from erosion by a concrete facing slab anchored back to the sound bedrock. -Spiliways As discussed above, che designed operation of the main spi,lway facilities was arranged to limit discharges of potentially nitrogen-supersaturated water from Watana to flows having an equivalent return period greater than 1:50 years. The main chute spillway and f'iip bucket discharge into an excavated plunge pool in the downstream river bed. Re- leases are controlled by a three-gated ogee structure located adjacent to the outlet facilities and power intake structure just upstream from th0 dam centerline. The design discharge is approximately 114,000 cfs, cor- responding to the routed 1:10,000-year flood (145,000 cfs) reduced by the 31,000 cfs flows attributable to out- let and power facilities discharges. The plunge pool is formed by excavating the alluvial river deposits to bed- rocko Since the excavated plunge pool approaches the 'limits of the calculated maximum scour hole; it is not anticipated that, given the infrequent discharges, sig- nificant downstream erosion will occur. An emergency spillway is provid2d by means of a channel excavated in rock on the north bank, discharging well downstream from the north abutment in the direction of Tsusena Creek. The channel is sealed by an erodible fuse pl~g of impervious material designed to fail if over- topped by the reservoir, although some preliminary exca- vation may be necessary. The crest level of the plug will be set at Elevation 2230, well below that of the main dam. The channel will be capable of passing the 2-37 .. I ' 1 L excess discharge of floods greater than the 1:10,000- year flood up to the probable maximum flood of 326,000 cfs. -Power Facil·ities The power intake is set slightly upstream from the dam axis deep within sound bedrock at the downstream end of the approach channel. The intake consists of six units with provision in each unit for drawing flows from a variety of depths covering the complete drawdown range of the reservoir. This facility also provides for draw- ing water from the different temperature strata within the upper part of the reservoir and thus regulating the temperature of the downstream discharges close to the natural temperatures of the river. For this preliminary conceptual arrangement, flow withdrawals from different levels a:e achieved by a series of upstream vertical shutters moving in a single set of guides and operated to form openings at the required level. Downstream from these shutters each unit has a pair of wheel-mounted closure gates which will iso1ate the individual pen- stocks. The six penstocks are 18-foot-diameter, concrete-lined tunnels ;.-,clined at 55° immediately downstream from the intake to a nearly horizontal portion leading to the powerhouse. This horizontal portion is steel-lined for 150 feet upstream from the turbine units to extend the seepage path to the powerhouse and reduce the flow with- in the fractured rock area caused by blasting in the adjacent powerhouse cavern. The six 170 MW turbine/generator units are housed within the major powerhouse cavern and are serviced by an over- head crane which runs the length of the powerhouse and into the service area adjacent to the units. Switch- gear, ma.intenance room and offices are located within the main cavern, with the transformers situated dawn- stream in a separate gallery excavated above the tail- race tunnels. Six inclined tunnels carry the connecting bus ducts from the main power hall to the transformer gallery. A vertical elevator and vent shaft run from the power cavern to the main office building and control room located at the surface. Vertical cable shafts, one for each pair of transformers, connect the transformer ga 11 er y to the swi tchyard direct 1 y overhead. C"Ownstream from the transformer gallery the underlying draft .tube tunnels merge into two surge chambers (one chamber for 2-38 L · ·11 .. r~ l ·\ I i I I I l three draft tubes) which also house the draft tube gates for isolating the units from the tailrace. The gates are operated by an overhead traveling gantry located in the upper part of each of the surge chambers. Emerging from the ends of the chambers, two concrete-lined, low- pressure tailrace tunnels carry the discharges to the river. Because of space restrictions at the river, one of these tunnels has been merged with the downstream end of the diversion tunnel. The other tunnel emerges in a separ~e portal with provision for the insta11~ion of bulkhead gates. The orientation of water passages and underground cav- erns is such as to avoid, as far as possible, alignment of the main excavations with the major joint sets. -Access Access is assumed to be from the north side of the river. Permanent access to structures c 1 ose to the river i s by a road a 1 on g the north down stream ri v er bank and then vi a a tunnel passing thn:wgh the concrete forming the flip bucket. A tunnel from this point to the power cavern provides for vehicular access. A secondary access road across the crest of the dam passes down the south bank of the valley and across the lcwer part of the dam. (ii) Scheme WP4A (Figure B.34) Th i s sc h erne i s s i mil ar i" most respects to Scheme WP3A pre- viously discussed, except for the spillway arrangements. -Main Dam The main dam axis is similar to that of Scheme WP3A, except for a s1 ight downstream rotation at the soc~th abutment at the spi 1 ~I way contr·o 1 structures. -Diversion The diversion and low levei releases are the same for the two schemes. 2-39 u l_J_ .. .. F.;J w I I . I -Outlet Facilities The outlet facilities used for emergency drawdown are separate from the main spillway for this scheme. The outlet facilities consists of a low-level gated inlet structure discharging up to 30,000 cfs into the river through a concrete-lined, free-flow tunnel with a ski jump flip bucket. This facility may also be operated as an auxiliary outlet to augment the main south bank spillway. -Spillways The main south bank spillway is capable of passing a design flow equivalent to the 1:10,000-year flood through a series of 50-foot drops into shallow pre- excavated plunge pools. The emergency spillway is designed to operate during floods of greater magnitude up to and including the PMF. Main spillway discharges are controlled by a broad multi-gated control structure discharging into a shallow stilling ba~in. The feasibility of this arrangement is governed by the quality of the rock in the area, requir- ing both durability~o withstand ero~ion caused by spillway flows and a high percentage a~ sound rockfill material that can be used from the excavat·~on directly in the main dam. On the basis of the site information developed concur- rently with the general arrangement studies, it became apparent that the major shear zone known to exist in the south bank area extended further downstream than initial studies have indicated. The cascade spillway channel was therefore lengthened to avoid the shear area at the lower end of the cascade. The arrangement shown on Figure 8.34 for Scheme WP4A does not reflect this relocation, which would increase the overal·. cost of the scheme. The emergency spillway consisting of rock channel and fuse plug is similar to that of the north bank spillway scheme. -Power Facilities The power facilities are similar to those in Scheme WP3A. • .. I l l l (iii) Evaluation of Final Alternative Schemes An evaluation of the dissimilar features for each arrange- ment (the main spillways and the discharge arrangements at the downstream end of the outlets) indicates a saving in capital cost of $197,000,000, excluding contingencies and indirect cost, in favor of Scheme WP3A. If this difference is adjusted for the savings associated with using an appro- priate proportion of excavated material from the cascade spillway as rockfill in the main dam, this represents a net overall cost diffe~ence of approximately $110,000,000 in- cluding contingencies, engineering, and administration costs. As discussed above, although limited ·information exists regarding the quality of the rock in the downstream area on the south bank, it is known that a major shear zone runs through and is adjacent to the area presently allocated to the spillway in Scheme WP4. This would require relocating the south bank cascade spillway several hundred feet farther downstream into an area where the rock qua 1 i ty is unknown and the topography 1ess suited to the gentle overall slope of the cascade. The cost of the excavation would substantially increase compared to previous assumptions, irrespective of the rock quality. In addition, the resistance of the rock to erosion and the suitability for use as excavated material in the main dam would become less certain. The economic feasibility of this scheme is largely predicated on this last factor, since the ability to use the material as a source of rockfi 11 for the main dam represents a major cost saving. In conjunction with the main chute spillway, the problem of the occurrence of nitrogen super·5aturatian can be overcome by the use of a regularly operated dispersion type valve o~tlet facility in conjunction with the main chute spill- way. Since this scheme presents a more economic solution with fewer potential prob1ems concerning the geotechnical aspects of its desifln, the nor·th bank chute arrangement (Scheme WP3A) has been adopted as the final selected scheme. 2.4 -Devil Canyon Project Formulation This section describes the development of the general arrangement of the Devil Canyon project. The method of handling floods during con~ struction and subsequent project operation is also outlined in this section~ 2-41 .. .. ' -~ J ... ~ ;,~.,._:;_;;_.2.__7~~;1 • -' ! j } ..d I cJ J ; ; L~ :j' "' J j J J 1 l J. ! J. ihe reservoir level fluctuations and inflow for Devil Canyon will es- sentially be controlled by operation of the upstream Watana project. This aspect is also briefly discussed in this section. (a) Selection of Reservoir Level The selected normal maximum operating level at Devil Canyon Dam is Elevation 1455. Studies by the USBR and COE on the Devil Canyon Project were essentially based on a sim·ilar reservoir level Hhich corresponds to the tailwater level selected at the Watan~ site. Although the narrow configuration of the Devil Canyon site and the rel~tively low costs involved in increasing the dam height suggest that it might be economic to do so, it is clear that the upper economic limit of reservoir level at Devil Canyon is the Watana tail race 1 eve l. Although significantly lower reservoir levels at Devil Canyon would lead to lower dam costs, the location of adequate spillway facilities in the narrow gorge would become extremely difficult and lead to offsetting increases in cost. In the extreme case, a spillway discharging over the d~m would raise concerns regarding safety from scouring at the toe of the dam which have already led to rejection of such schemes. (b) Selection of Installed Capacity Tne methodology used for the preliminary selection of installed capacity at Devil Canyon is s·imilar to the Watana methodology described in Section 2.2(b). The decision to operate Devi 1 Canyon primarily as a base-loaded plant was governed by the following main considerations: -Daily peaking is more effectively performed at Watana than at Devil Canyon; and Excessive fluctuations in discharge from the Devil Canyon dam may have an undesirable impact on mitigati1n measures incorpor- ated in the final design to project the downstream fisheries. Given this mode of operation) the required installed capacity at Devil Canyon has been determined a~ the maximum capacity needed to utilize the available energy from the hydrological flows of record, as m0dified by the ~·eservoir operation rule curves. In years where the energy from Watana and Devil Canyon exceeds the syste.m demand, the usab 1 e energy has been reduced at both stat ions in proportion to the average net head available, assuming that flows used to gener--ate energy at Watana will also be used to gen- erate ene1rgy at Devi 1 Canyon.. 2-42 • . , " . ,.J---.:.....,J:;~lf-t\,~-M~,. '•"""---~-~ '""~ l l t t l .._:_' . Table 8.32 shows an assessment of maximum plant capacity required at Devil Canyon in the peak demand month (December). The Devil Canyon capacity is the same whether thermal energy is used for base load or for peaking since Devil Canyon is designed for peaking only. The selected total installed capacity at Devil Canyon has been established as 600 MW for design purposes. This will orovide some margin for standby during forced outage and possible accelerated growth in demand. The major factors governing the selection of the·unit size at Devil Canyon are the rate of growth of system demand, the minimum station output, and the requirement of standby capacity under forced outage conditions. The power facilities at Devil Canyon have been developed using four units at 150 MW each. This arrangement will provide for efficient station operation during low 1oad periods as well as during peak December loads. During final design, consideration of phasing of installed capacity to match the system demand may be desirable. However, the uncertainty of load forecasts and the additional contractual costs of mobilization for equipment instal- lation are such that for this study it has been assumed that all units will be commissioned by 2002. The Devil Canyon reservoir will usually be full in December; hence, any forced outage could result in spilling and a loss of available energy. The units have been rated to deliver 150 MW at maximum December drawdown occuring during an extremely dry year; this means that in an average year, wit~ higher reservoir levels th~ full station output can be maintain~d even with one unit on forced outage. (c) Selec;tio..!l_of Spi1lway Capacity A flood frequency of 1:10,000 years was selected for the spillway design on the same basis as described for Watana~ An emergency spillway with an erodible fuse plug will also be provided to safely discharge the probable maximum flood. The development plan envisages completion of the Watana project prior to construction at Devil Canyon. Accordingly, the inflow flood peaks at Devil Canyon will be less than pre-project flood peaks because of rant- ing through the Watana reservoir. Spil1way design f1oods are: Flood 1:10,000 years Probable Maximum 2-43 Inflow Peak (cfs) 165,000 345,000 .. 1 I j I I I "·-+-. '• -~ ~-~·-..--··.· ' The avoidance of nitrogen supersaturation in the downstream flow for Watana also will apply to Devil Canyon. Thus, the discharge of water possibly supersaturated with nitrogen from Devil Canyon will be limited to a ~ecurrence period of not less than 1:50 years by the use of fixed-cone valves similar to Watana. (d) Main Dam Alternatives The location of the Devil Canyon damsite was examined during pre~ vious studies by the USBR and COE. These studies focused on the narrow entrance to the canyon and led to the recommendation of a concrete arch dam. Notwithstanding this initial appraisal, a com- parative analysis was undertaken as part of this feasibility study to evaluate the relative merits of the following types of struc- tures at the same location: -Thick concrete arch; -Thin concrete arch; and -Fill embankment. (i) Comparison of Embankment and Concrete Type Dams The geometry was developed for both the thin concrete arch and the thick concrete arch dam and the dams were analyzed and thei~ behavior compared under static, hydrostatic, and seismic loading conditions. The project layouts for these arch dams were compared to a layout for a rockfill dam with its associated structures. Consideration of the central core rockfill dam layout indi- cated relatively small cost differences from an arch dam cost estimate, based on a cross-section significantly thicker than the finally selected design. Furthermore, no information was avtilable to indicate that impervious cm~e material in the necessary quantities could be found within a reasonable distance of the damsite. The rockfill dam wt.J.:~ accordingly dropped from further consideration. It is further noted that since this alternative dam study, seismic anaiysis of the rockfill dam at Watana has resulte:d in an upstream slope 1:2.4, thus indicating the requirement to flatten the 1:2.5 slope adopted for the rockfill dam alternative at Devil Canyon. Neither of the concrete arch dam layouts were intended as the final site arrangement, but were sufficiently representative of the most suit ab 1 e arrangement associated with each dam type to provide an adequate basis for comparison. Each type of dam was located just downstream from where the river enters Devil Canyon and close to the 2-44 •• .. • • ... ' -• et.. . . ·• , .• . . . '" \ . . . . . . . , J j J I .J. j J l I I I canyon•s narrowest point, which is the optimum location for all types of Jams. A brief description of each dam type and configuration is given below. -Rockfill Dam For this arrangement the dam axis would be some 625 feet downstream of the crown section of the concrete dams. The assumed embankment slopes would be 2.25 H:lV on the upstream face and 2H:1V on the downstream face. The main dam would be continuous with the south bank saddle dam, and therefore no thrust blocks would be required. The crest length would be 2200 feet at Elevation 1470; the crest width would be 50 feet. The dam would be constructed with a central impervious core, inclined upstream, supported on the downstream side by a semi-pervious zone. These two zones would be protected upstream and downstream by filter and transition materials. The shell sections would be constructed of rockfill obtained from blasted bedrock. For preliminary design all dam sections would be assumed to be founded on rock; external cofferdams would be founded on the river alluvium, and would not be incorporated into the main dam. The approximate volume of material in the main dam would be 20 million cubic yards. A single spillway would be provided on the north abutment to control all flood flows. It would consist of a gate control structure and a double stilling basin excavated into rock; the chute sections and stilling basins would be concrete-lined, with mass concrete gravity retaining walls. The design capacity would be sufficient to pass the 1:10,000 year flood without damage; excess capacity would be provided to pass the PMF without damage to the main da1.1 by surcharging the rest::rvo ;r and spillway. The powerhouse waul d be 1 ocated und~~rground in the north abutment. The multi-level power intake would be constructed in a rock cut in the north abutment on the dam centerline, with four independent penstocks to the 150 MW Francis turbines. Twin concrete-lined tailrace tunnels would connect the powerhouse to the river via an intermediate draft tube manifo1d. -Thick Arch Dam The main concrete dam would be a single center arch structure, acting partly as a gravity dam, with a vertical cylindrical upstream face and a sloping downstream face inclined at 1V:0.4H. The maximum height of the dam would be 635 feet ith a uniform crest width of 2-45 • • J J l L 30 feet, a crest length of approximately 1,400 feet 9 and a maximum foundation width of 225 feet. The crest elevation would be 1460. The center portion of the dam would be founded on a massive mass concrete pad constructed in the excavated river bed. This central section would incorporate the main spillway with sidewalls anchored into solid bedrock and gated orifice spillways discharging down the steeply inclined downstream face of the dam into a single large stilling basin set below river level and spanning the valley. The main dam would terminate in thrust blocks high on the abutments. The south abutment thrust block would incorpora~e an emergency gated conttol spillway structure which would discharge into a rock channel running well downstream and terminating at a level high above the river valley. Beyond the control structure and thrust block, a low- lying saddle on the south abutment would be closed by means of a rockfill dike founded on bedrock. The powerhouse would house four 150 MW units and would be located underground within the north abutment. The intake would be constructed integrally with the dam and connected to the powerhouse by vertical steel-lined penstocks. The main spillway would be designed to pass the 1:10,000-year routed flood with larger floods discharged downstream via the emergency spillway. -Thin Arch Dam The main dam would be a two-center, double-curved arch structure of similar height to the thick arch dam, but with a 20-foot uniform crest and a maximum base width of 90 feet. The crest elevation \\'Ould be 1460. The center section wouid b~ founded on a concrete pad, and the extreme upper portion of the dam would terminate in con- crete thrust blocks located on the abutments. The main spillway would be located on the north abutment and would consist of a conventional gated control struc- ture discharging down a concrete-lined chute terminating in a flip bucket. The bucket would discharge into an unlined plunge pool excavated in the riverbed alluvium and located sufficiently downstream to prevent under- mining of the dam and associated structures. 2 4 .,., ... b , • .\) J I ,J . 1 l J j J l The main spillway would be supplemented by orifice type spillwaJs located high in the center portion of the dam which would discharge into a concrete-lined plunge pool immediately downstream from the dam. An emergency spillway consisting of a fuse plug discharging into an unlined rock channel terminating well downstream would be located beyond the saddle dam on the south abutment. The concrete dam would terminate in a massive thrust block on each abutment which, on the south abutment, would adjoin a rockfill sa~dle dam. The main and auxiliary spillways would be designed to discharge the 1:10,000-year flood. Larger floods for storms up to the probable maximum flood would be dis- charged through the emergency south abutment spillway. -~omparison of Arch Dam Types Sand and gravel for concrete aggregates are believed to be available in sufficient quantities within economic distance from the damsite. The gravel and sands are formed from the granitic and metamorphic rocks of the area; at this time it is anticipated that they will be suitable for the production of aggregate~ after screen- ing and washing. The bedrock g~ology of the site is discussed in Refer- ence 3. At this time it appears that there are no geo- logical or geotechnical concerns that would preclude either of the dam types from consideration . Under hydrostatic and temperature loadings, stresses within the thick arch dam would be generally lower ~han for the thin arch alternative. However, finite element analysis has shown that the additional mass of the dam under seismic loading would produce stresses of a greater magnitude in the thick arch dam than in the thin arch dam. If the surface stresses approach the maximum allowable at a particular section, the remaining under- stressed ar~ea of concrete wi 11 be greater for the thick arch, and the factor of safety for the dam would be ~or­ respondingly higher. The thin arch is, however, a more efficient design and better utilizes the inherent pro- perties of the concrete. It is designed around accept- able predetermined factors of safety and requires a much smaller vo 1 ume of concrete for the actual dam struc- tur·e. 2-47 ; I I I l lt J j 1 1 l L (> .. -.. -·· --~-· -----·---· ~----.---------·-·-·· .. -···--··-····--· The thick arch arrangement did not appear to have a distinct te~hnical advantage compared to a thin arch dam and would be more expensive because of the larger volume of concrete needed. Studies, therefore, continued on refining the feasibility of the thin arch alternativea (e) Diversion Scheme Alternatives In this section the selection of general arrangement and the basis for sizing of the diversion scheme are presented. (i) General Arrangements (ii) The steep walled valley at the site essentially dictated that diversion of the river during construction be accom- plished using one or two diversion tunnels, with upstream and downstream cofferdams protecting the main construction area. The selection process for establishing the final general arrangement included examination of tunnel locations on both banks of the river. Rock conditions for tunneling did not favor one bank over the other. Access and ease of con- struction strongly favored the south bank or abutment, the obvious approach being via the alluvial fan. The total length of tunnel required for the south bank is approximately 300 feet greater; however, access to the north bank could not be achieved without great difficulty. Design Flood for Diversion The recurrence interval of the design flood for diversion was established in the same manner as for Watana dam. Accordingly, at Devil Canyon a risk of exceedence of 10 percent per annum has been adopted, equivalent to a design flood with a 1:10-year return period for each year of crit- ical construction exposure. The critical construction time is estimated at 2.5 years. The main dam could be subjected to overtopping during construction without caus- ing serious damage, and the existence of the Watana facil- ity upstream would offer considerable assistance in flow regulation in case of an emergency. These considerations led to the selection of the design flood with a return frequency of 1:25 years. The equivalent inflow, together with average flow charac- teristics of the river significant to diversion, are pre- sented below: -Average annual flow: 9,050 cfs -Design flood inflow (1:25 years routed through Watana reservoir): 37,800 cfs 2-48 ··~ j ] J I .J ,I J J ! 1 (iii) Cofferdams ( i v j (v) As at Watana, the considerable depth of riverbed alluvium at both cofferdam sites indicates that embankment-type cof- ferdam structures would be the only technically and econom- ically feasible alternative at Devil Canyon. Fer the pur- poses of establishing the overall general arrangement of the project and for subsequent diversion optimization studies, the upstream cofferdam section adopted will com- prise an initial closure section approximately 20 feet high constructed in the wet, with a zoned embankment constructed in the dry. The downstream cofferdam will comprise a clos- ure dam structure approximately 30 feet high placed in the wet. Contra 1 of underseepage through the a 11 uvi urn materia 1 may be required and could be achieved by means of a grouted zone. The coarse nature of the alluvium at Devil Canyon led to the selection of a grouted zone rather than a slurry wall. Diversion Tunnels Although studies for the Watana project indicated that concrete-lined tunnels are the most economically and technically feasible solution, this aspect was reexamined at Devil Canyon. Preliminary hydraulic studies indicated that the design flood routed through the diversion scheme would result in a design discharge of approximately 37,800 cfs. For concrete-lined tunnels, design velocities of approximately 50 ft/s would permit the use of one concrete-lined tunnel with an equivalent diameter of 30 feet. Alternatively, for unlined tunnels a maximum design velocity of 10 ft/s in good quality rock would require four unlined tunnels, each with an equivalent diameter of 35 feet, to pass the design flow. As was the case for the Watana diversion scheme, considerations of reliability and cost were considered sufficient to eliminate consideration of unlined tunnels for the diversion scheme. For the purposes of optimization studies, on'ly a pressure tunnel was considered, since previous studies indicated that cofferdam closure problems associated with free-flow tunnels would more than offset their other advantages. Optimization of Diversion Scheme Given the considerations described above relative to design flows, cofferdam configuration, and alternative types of tunnels, an economic study was undertaken to determine the optimum combination of upstream cofferdam elevation (height) and tunnel diameter. 2-49 ·~ J i ,J . J J J .J J I .! J Capital costs were developed for a range of pressure tunnel diameters and corresponding upstream cofferdam embankment crest elevations with a 30-foot wide crest and exterior slopes of 2H:1V. A freeboard allowance of 5 feet was included for settlement and wave runup. Capital costs for the tunnel alternatives included allow- ances for excavation, concrete liner, rock bolts, and steel supports. Costs were also developed for the upstream and downstream portals, including excavation and support. The cost of an intake gate structure and associated gates was determined not to vary significantly with tunnel diameter and was excluded from ~he analysis. The centerline tunnel length in all cases was estimated to be 2,000 feet. Rating curves for the single-pressure tunnel alternatives are presented in Figure 8.35. The relationship between capital costs for the ups.tream cofferdam ard various tunnel diameters is given in Figure 8.36. The results of the optimization study indicated that a single 3D-foot-diameter pressure tunnel results in the overall least cost (Figure B.36). An upstream cofferdam 60 feet high, with a crest elevation of 945, was carried for- ward as part of the selected general arrangement • (f) Spillway Alternatives The project spill ways have been designed to safely pass floods with the following return frequencies: Inflow Peak Flood Spillway Design Probable Maximum Discharge Frequency 1:10,000 years Inflow (cfs) 165,000 345,000 A number of alternatives were considered singly and in combination for Devil Canyon spillway faci 1 iti es. These included gated ori- fices in the main dam discharging into a plunge po0l, chute or tunnel spillways with either a flip bucket or stilling basin for energy di ss i pati on, and open channe 1 spillways. As described for Watana, the selection of the type of spillway was influenced by the general arrangement of the major structures. The main spill- way facilities would discharge the spillway design flood through a gated spillway control structure with energy dissipation by a flip bucket which directs the spillway discharge in a free fall jet 2-50 ,. .. • J I J j J J J J J .I .I l into a plunge pool in the river. As noted above, restrictions with respect to limiting nitrogen supersaturation in selecting acceptable spillway discharge structures have been applied. The various spillway arrangements developed in accordance with these considerations are discussed in Section 2.5. (g) Power Facilities Alternatives The selection of the optimum arrangements for the power facilities involved consideration of the same factors as described for Watana. ( i ) Comparison of Surface and Underground Powerhouses A surface powerhouse at Devil Canyon would be located either at the downstream toe of the dam or along the side of the canyon wall. As determined for Watana, costs fav- ored an underground arrangement. In addition to cost~ the underground powerhouse layout has been selected based on the follo\"Jing: Insufficient space is available in the steep-sided canyon for a surface powerhouse at the base of the dam; -The provision of an extensive intake at the crest of the arch dam would be detrimental to stress conditions in the arch dam, particularly under earthquake loading, and would require significant changes in the arch dam geo- metry; and -The outlet facilities located in the arch dam are designed to discharge directly into the river valley; these would cause significant winter icing and spray problems to any surface structure below the dam. (ii) Comparison of Alternative Locations The underground powerhouse and related facilities have been located on the north bank for the following reasons: -Generally superior rock quality at depth; The south bank area behind t~e main dam thrust block is unsuitable for the construction of the power intake; and -The river turns north downstream from the dam, and hence the north bank power development is more suitable for extending the tailrace tunnel to develop extra head. (iii) Selection of Units The turbine type selected for the Devil Canyon development is governed by the design head and specific speed and by 2-51 economic considerations. Francis turbines have been adopted for reasons similar to those discussed for Watana in Section 2.2(g). The selection of the nwnber and rating of individual units is discussed in detail in Section 2.4(b). The four units will be rated to deliver 150 MW each at full gate opening and minimum reservoir ~evel in December (the peak demanci month). (iv) Transformers Transformer selection is similar to Watana (Section 2.2(g)(v)). (v) Power Intak~ and Water Passages For flexibility of operation, individual penstocks are pro- vided to each of the four units. Detdiled cost studies showed that there is no significant cost advantage in using two larger diameter penstocks with bifurcation at the pow- erhouse compared to four separate penstocks. A single tailrace tunnel with a length of 6,800 f~et to develop 30 feet of additional head downstream from the dam has been incorporated in the design. Detailed design may indicate that two smaller tailrace tunnels for improved reliability may be superior to one large tunnel since the extra cost involved is relatively small. The surge chamber design would be essentially the same with one or two tun- nels. The overall dimensions of the intake structure are governed by the selected diameter and number of the penstocks and the minimum penstock spacing. Detailed studies comparing construction cost to the value of energy lost or gained w~re carried out to determine th~ ~ptimum diameter of the penstocks and the tai !race tunnel. (vi) Environmental Constraints In addition to potential nitrogen-saturation problems caused by spillway operation, the major impacts of the Devil Canyon power facilities development are: -Changes in the temperature regime of the river; and -Fluctuations in downstream river flows and levels. Temperature modeling has indic~ed that a multiple level intake design at Devil Canyon would aid in controlling downstream water t~mperatures. 2-52 I J 2.5 Consequently, the intake design at Devil Canyon incorporates two levels of draw-off. The Devil Canyon station will normally be operated as a base-loaded plant throughout the year to satisfy the requirement of no significant daily vari~tion in power flow. Selection of iJevil Canyon General Arrangement The approach to selection of a general arrangement for Devil Canyon was a similar but simplified version of that used for Watana. (a) Selection Methodology (b) (c) Preliminary alternative arrangements of the Devil Canyon project were developed and selected using two rather than three review stages. Topographic conditions at this site limited the develop- ment of reasonably feasible layouts, and four schemes were ini- tially developed and evaluated. During the final review, the sel- ected layout was refined based on technical, operational and envi- ronmental considerations identified during the preliminary review. Design Data and Criteria The design data and design criteria on which the alternative lay- outs were based are presented in Table 8.33. Subsequent to selec- tion of the preferred Devil Canyon scheme, the information was refined and updated as part of the on-going study program. Preliminary Review Consideration of the options available for types and locations of various structures led to the development of four primary layouts for examination at Devil Canyon in the preliminary review phase. Previous studies had led to the selection of a thin concrete arch structure for the main dam, and indicated that the most acceptable technical and economic loc~tion was at the upstream entrance to the canyon. The dam axis has been fixed in this location for all alternatives. ( i) Description of Alternative Schemes The schemes evaluated during the preliminary review are describea below. In each of the alternatives eval~ated, the dam is founded on the sound bedrock underlying the riverbed. The str·..:cture is 635 feet high, has a crest width of 20 feet, and a maximum base width of 90 feet. Mass concrete thrust blocks are founded high on the abut- ments, the south block extending approximately 100 feet 2-53 • • -.~ '~ I I I I I I i ' ,, ·~,. . "·-() .... ,,c . "----~"""" .... --~ above the existing bedrock surface and supporting the upper arches of the dam. The thrust block on the north abutment makes the cross-river profile of the dam more symmetrical and contributes to a more uniform stress distribution. -Scheme DC1 (Figure 8.37) In this scheme, diversion facilities comprise upstream and downstream earthfill and rockfill cofferdams and two 24-foot-diameter tunnels beneath the south abutment. A rockfill saddle dam occupies the lower lying area beyond the south abutment running from the thrust block to the higher ground beyond. The impervious fill cut- off for the saddle dam is founded on bedrock approximately 80 feet beneath the existing ground surface. The maximum height of this dam above the foundation is approximately 200 feet. The routed 1:10,000-year design flood of 165,0CO cfs is passed by two spillways. The main spillway is located on the north abutment. It has a design discharge of 120,000 cfs, and flows are controlled by a three-gated agee control structure. This discharges down a concrete-lined chute and over a flip bucket which ejects the water in a diverging jet into a pre-excavated plunge pool in the riverbed. The flip bucket is set at Elevation 925, approximately 35 feet above the river level. An auxiliary spillway discharging a total of 35,000 cfs is located in the center of the dam, 100 feet below the dam crest, and is controlled by three wheel-mounted gates. The orif·ices are designed to direct the flow into a concrete-lined plunge pool just downstream from the dam. An ~~ergency spillway is located in the sound rock south of the saddle dam. This is designed to pass discharges in excess of the 1:10,000-year flood up to a probable maximum flood of 345,000 cfs, if such an event should ever occur. The spillway is arr unlined rock ~hannel which discharges into a valley downstream from the dam leading into the Susitna River. The upstream end of the channel is closed by an earth- fill fuse plug. The plug is designed to be eroded if overtopped by the reservoir. Since the crest is lower than either the main or saddle dams, the plug would be washed out prior to overtopping of either of these structures. The underground power facilities are located on the north bank of the river, within the bedroc~ forming the 2-54 .. I l I I I I dam abutment. The rock within this abutment is of better quality with fewer shear zones and a lesser degree of jointing than the rock on the south side of the canyon, and hence more suitable for underground excavation. The power intake is located just upstream from the bend in the valley before it turns sharply to the right into Devil Canyon. The intake structure is set deep into the rock at the downstream end of the approach channel. Separate penstocks for each unit lead to the power-house. The powerhouse contains four 150 MW turbine/generator units. The turbines are Francis type units coupled to overhead umbrella type generatorsG The units are serviced by an overhead crane running the length of the powerhouse and into the end service bay. Offices, the control room, switchgear room, maintenance room, etc., are ·located beyond the service bay. The transformers are housed in a separate upstream gallery located above the lower horizontal section of the penstocks. Two vertical cable shafts connect the gallery to the sur- face. The draft tube gates are housed above the draft tubes in separate annexes off the main powerhall. The draft tubes converge in two bifurcations at the tailrace tunnels which discharge under free-flow conditions to the river. Access to the powerhouse is by means of an unlined tunnel leading from an access portal on the north side of the :anyon. The switchyard is located on the south bank of the river just downstream from the saddle dam, and the power cables from the transformers are carried to it across the top of the dam. -Scheme DC2 (Figure 8.38) The layout i·s gen.=ra lly similar to Scheme DCl except that the chute sp·.:llway is located on the south side of the canyon. The concrete-lined chute terminates in a flip bucket high on the south side of the canyon which drops the discharges into the river below. The design flow is 120,000 cfs, and discharges are controlled by a 3-gated, agee-crested control structure similar to that for Scheme DCl which abuts the south side thrust block. The saddle dam axis is straight, following the shortest route between the control structure at one end and the rising ground beyond the low-lying area at the other. 2-55 I I I J J j -Scheme DC3 {See Figure 8.39) The layout is similar to Scheme DCl except that the north side main spillway takes the fol'·m of a sing·le tunnel rather than an open chute. A 2-gated, agee-- control structure is located at the head of the tunnel and discharges into an inclined shaft 45 feet diameter at its upper end~ The structure wi11 discharge up to a maximum of 120,000 cfs. The concrete-lined tunnel narrows to 35 feet diameter and discharges into a flip bucket which directs the flows in a jet into the river below as in Scheme DCl. An auxiliary spillway is located in the center of the dam and an emergency spillway is excavated on the south abutment . . The layout of dams and power facilities are the same as for Scheme DGl. -Scheme DC4 {See Figure 8.40) __ , __ _ The dam, power facilities) and saddle dam for this scheme are the same as those for Scheme DCl. The major difference is the substitution of a stilling-basin type spillway on the north bank for the chute and flip bucket. A 3-gated, agee-control structure is located at the end of the dam thrust block and controls the dis- charges up to 3 maximum of 120,000 cfs, The concrete-lined chute is built into the face of the ca!1yon and discharges into a 500-foot-long by 115-foot- wide by 100-foot~high concrete stilling basin formed below river level and deep within the north side of the canyon. Central orifi.ces in the dam and the south bank rock channel and fuse plug form the auxiliary and emergency spillways, respectively, as in the other alternative schemes. The downstream cofferdam is located beyond the stilling basin and the diversion tunnel outlets are located farther downstream to enable ~onstruction of the stilling basin. (ii) Comp~rison of Alternatives i • "" • • Q .. . The arch dam, saddle dam, power facilities, and diversion vary only in a minor degree among the four alternatives. Thus, the comparison of the schemes rests solely on a com- par·ison of the spillway facilities. 2-56 ----_J__ . . ; ~ . --~ --. ~ • .. ·.' .· ~ . -. •. : __ ·-.. -_ ._· '._.-.-.-.~~ ·.·._-:..:--.. -~·---~--~~-~--~---------__ .. :......~- 1 I • •• I As can be seen from a comparison of the costs in Table B¥34, the flip bucket spillways are substantirlly less costly to construct than the stilling-basin type of Scheme DC4. The south side spillway of Scheme DC2 runs at a sharp angle to the river and ejects the discharge jet f~om high on the canyon face toward the opposite side of the canyon. Over a longer period of operation, scour of the heavily jointed rock could cause undermining of the canyon sides and their subsequent instability. The possibility also exists of deposition of material in the downstream riverbed with a corresponding elevation of the tailrace. Construction of a spillway on the steep south side of the river could be more difficult th~n on the north side because of the presence of deep fissures and large unstable blocks of rock which are present on the south side close to the top of the canyon. The two north side flip bucket spillway schemes, based on either an open chute or a tunnel, take advantage of a down- stream bend in the river to discharge parallel to the course of the river. This will reduce the effects of erosion but could still present a problem if the estimated maximum possible scour hole would occur. The tunnel type spillway could prove difficult to construct because of the large diameter inclined shaft and tunnel raralleling the bedding planes. The high velocities en- counter·8d in the tunnel spillway could cause problems with the possibility of spiraling flows and severe cav~tation both occuring . The stilling basin type spillway of Scheme DC4 reduces downstream erosion problems within the canyon. However, cavitation could be a problem under the high-flow veloci- ties experienced at the base of the chute. This would be somewhat alleviated by aeration of the flows. There is, however, little precedent for stilling basin operation at heads of over 500 feet; even where floods of much less than the design capacity have been discharged, severe damage has occurr~d. (iii) Selection of Final Scheme The chute and flip bucket spillway of Scheme OC2 could gen- erate downstream erosion problems which could require con- siderable maintenance costs and cause reduced efficiency in operation of the project at a future date. Hydraulic design problems exist with Scheme OC3 which may also t~ve 2-57 ... ] ] ] 1 I ' ' I ,I I I severe cavitation problems. Also: there is no cost advantage in Scheme DC3 over the open chute Scheme DC1. In Scheme DC4, the operating characteristics of a high head stilling basin are little known, and there are few exampl€s of successful operation. Scheme DC4 also costs cons~derably more than any other scheme (Table 8.30)~ All spillways operating at the required heads and dis·- charges will eventually cause some erosion. For all schemes, the use of solid cone valve outlet facilities in the lower portion of the dam to handle floods up to 1:50-year frequency is considered a more reasonable approach to reduce erosion and eliminate nitrogen super- saturation problems than the gated high li!vel or)rice out- lets in the dam. Since the cost of the flip bucket type spillway in the scheme is considerably less than that of the stilling basin in Scheme DC4, and since the latter offers no relative operational advantage, Scheme DCl has been selected for further study as the selected scheme. (d) Final Review The layout selected in the previous section was further developed in accordance with uprl~ted engineering studies and criteria. The major change compared to Scheme DC1 is the elimination of the high level gated orifices and introduction of low level fixed-cone valves, but other modifications that were introduced are described below. The revised layout is shown on Figure 8.41. structu;·es is as fo 11 ows. (i) Main Dam A description of the The maximum operating level of the reservoir was raised to Elevation 1455 in accordance with updated information rela- tive to the Watana tailwater level. This requires raising the ddm crest to Elevation 1463 with the concrete parapet wall crest at Elevation 1466. The saddle dam was raised to Elevation 1472. (ii) Spillways and Outlet Facilities To eliminate the potential for nitrogen supersaturation problems, the outlet facilities were designed to restrict supersaturated flow to an average recurrence interval of greater than 50 years. This led to the replacement of high level gated orifice spillway by outlet facilities incorpor- ating 7 fixed-cone valves, 3 with a diameter of 90 inches 2-58 .. J ] ] ] J '·jr.· k J I J I ] ,, ~-· _, __________ ~ ""' ~"~~----..<----··--·--~-.~--··----~~·'-···,.._.,., ... ______ _ and 4 with a diameter of 102 inches, capable of passing a design flow of 38,500 cfs. The chute spillway and flip bucket are located on the north bank, as in Scheme DC1; however, the chute length was decreased and the elevation of the flip bucket raised com-pared to Scheme DC1o More recent site surveys indicated that the ground surface in the vicinity of the saddle dam was lower than originally estimated. The emergency spillway channel was relocated slightly to the south to accommodate the larger dam. (iii) Diversion The previous twin diversion tunnels were replaced by a single-tunnel scheme. This was determined to provide all necessary security and will cost approximately one-half as much as the two-tunnel alternative. (iv) Power Facilities The drawdown range of the reservoir was reduced, allowing a reduction in height of the power intake. In order to locate the intake within solid rock, it has been moved into the side of the valley~ requiring a slight rotation of the water· pa£sages, powerhouse, and caverns comprising the power facilities. 2.6 -Selection of Access Road Corridor (a) Previous Studies The potential for hydroelectric power generation within the Susitna Basin has been the subject of considerable investigation over the years as is described in Section 1.1 of this exhibit. These studies produced much tnformation on alternative development plans but little on the question of access. The first report to incorporate an access plan was that of the Corps of Engineers in 1975. The proposed pla~ consisted of a 24 foo~-wide road with a design speed of 30 miles per hour that connected with the Parks Highway near Chulitna Station, paralleled the Alaska railroad south and east to a crnssing of the Susitna River then proceeded up the south side of the river to Devil Canyon. The road continued on the south side of the Susitna River to Watana, passing by the north end of Stephan Lake and the west end of the Fog Lakes. In addition a railhead facility was to be constructed at Gold Creek. This plan is s·imilar to one of the selected alternative plans, Plan 16 (South), discussed later in this section. 2-59 .. .. 1·. .. I I Other studies crmcerning the Susitna Hydroelectric Project mentioned access ~nly in passing and did not involve the development of an access plan. {b) Selection Process Constraints Throughout the development 9 evaluation and selection of the access plans the foremost objective has been to provide a transportation system that waul d support construction activities and a 11 ow for the orderly development and maintenance of site facilities~ Meeting this fundamental objective involved the consideration not only of economics and technical ease of development but als0 ma~y other d i v_erse factors. Of prime importance was the potentia 1 for impacts to the environment, namely impacts to the local fish and game populations. In addition since the Native villages and the Cook Inlet Region will eventually acquire surface and subsurface rights, their interests were recognized and taken into account as were those of the local communities and general pubiic. With so many different factors influencing the choice of an access plan it is evident that no one plan will satisfy all interests. The aim during the selection process has been to consider all factors in their proper perspective anct produce a plan that represents the most favorable solution to meeting both project related goals and minimizing impacts to the environment and surrounding communities. · (c) Corridor Identification and Selection Three general corridors were identified leading from the existing transportation network to the damsites. This network consists of the Parks Highway and the Alaska Railroad to the west of the damsites and the Denali Highway to the north. The three general corridors are identified in figure 8.42. Corridor 1 -From the Parks Highway to the Watana damsite via the north side of the Susitna River. Corridor 2 -From the Parks Highway to the Watana damsite via the south side of the Susitna River. Corridor 3 -From the Denali Highway to the Watana damsite. The access road studies identifi~d a total of eighteeen alternative plans within the three r.orridors. The alternatives were developed by laying out routes en topograph1cal maps in accordance with accepted road and rail design criteria. Subsequent field investigations re£ulted in minor modifications to reduce environmental impacts and improve alignment. 2-60 . I • • • • . . . ... . . . ... " --' 0 • • ~ ' \ • • ,# ll • -""' ... ' . Gl ...... Q - I I I I I I I l ' l l . ' t ',•;) -~··--~--··-"-··---'4' ', D ,,'!!!', -----''--~-----·· ____ .. (d) Development of P1ans At the beginning of the study a plan formulation and initial selection process was developed. The criteria that most significantly affected the selection process were identified as: -Minimizing impacts to the environment; -Minimizing total project costs; Providing transportation flexibility to minimize construction risks; Providing ease of operation and maintenance; and -Pre-construction of a pioneer road. During evaluation of the access plans, input from the public agencies and Native organizations was sought and their response resulted in an expansion of the original list of eight alternative plans to eleven. These studies culminated in the production of the Access Route Selection Report (15) which recommended Plan 5 as the route which most closely satisfies the selection criteria. Plan 5 starts from the P~rks Highway near Hurricane and traverses southeast along the Indian River to Gold Creek. From Gold Creek the road continues east on the south side of the Susitna River to the Devil Canyon damsite~ crosses a low level bridge and continues east on the north side of the Susitn& River to the Watana damsite. For the project to remain on schedule it would have been necessary to construct a pioneer road along this route prior to the FERC license being issued. In March of 1982 the Alaska Power Authority presented the results of the Susitna Hydroelectric Feasiblity Report (4), of which access plan 5 was a part, to the public, agenc1qs and organizations. During April comment was obtained relative to the Feasibility Study from the~e groups. As a result of these comments the p1oneer road concept was eliminated, rhe evaluation criteria were refined, and six additional access alternatives were developed. During the evaluatiun process Alaska Power Authority (APA) formulated a further plan, thus increasing the total number of plans under evaluation to eighteen. This subsequently became the plan recommended by APA staff to the APA Board or Directors, and was formally adopted as the Proposed Access Plan in September 1982. (e) Evaluation of Plans The refined criteria used to evaluate the eighteen alternative access plans were; -No pre-license construction -Minimize environmental impacts -Minimize construction duration -Provide access ~etween sites during project operation phase 2-61 • I I I I I I I ' I '~ I I 1 .\._.,'.) . "'-· -~·-"' '-~·-'"···-.... ~_,, __ ,_, ____ _,____ '·---------~ .. ::_ __ ~-----------------,'.:-... ,. ''"'"' ' "--" --· ,_, __ ,, '"• ,,.,,,,,.~-·"'""-"'""' , _______ .:,_, __ ,, _____ .. _ _;,._';_·".~---~-~---····~---·""'·"'-"··-··_ .. -,.;._,___,..:,_ ...... Provide access flexibility to ensure project is.brought on-line within budget and schedule -Minimize total cost of access -Minimize initial investment required to provide a~cess to the Watana damsite -Minimize risks to project schedule Accommodate current land uses and plans Accommodate Agency preferences Accommodate preferences of Native organizations Accommodate preferences of local communities -Accommodate public concerns All eighteen plans were evaluated using these refined criteria to determine the most responsive access plan in each of the three basic corridors. To meet the overall project schedule requirements for the Watana development it is necessary to secure initial access to the Watana damsite within one year of the FERC license being issued. The constraint of no pre-license construction resulted in the elimination of any plan in which initial access could not be completed within one year. This constraint eliminated six plans (plans 2, 5, 8, 9, 10, 12) from further consideration. On completion of both the Watana and Devil Canyon dams it is planned to operate and maintain both sites from one central location, Watana. To facilitate these operation and maintenance activites access plans with a road connection between the sites were considered superior to those plans without a road connection. Plans 3 and 4 do not have access between the sites and were discarded. The ability +o make full use of both rail and road systems from southcentral ports of entry to the railhead facility provides the project management with far greater flexibility to meet contingencies, and control costs and schedule. Limited access plans utilizing an all rail or rail link system with no road connection to an existing highway have less flexibility and would impose a restraint on project operation that could result in delays and significant increases in cost. Four plans with limited access (plans 8, 9, 10 and 15) were eliminated because of this constraint. Residents of the Indian River and Gold Creek communities are generally not in favor of a road access near their communities. Plan 1 was discarded because plans 13 and 14 achieve the same objectives without impacting the Indian River and Gold Creek areas. 2-62 .. .. I I I • • P1an 7 was eliminated because it includes a circuit route connecting to both the George Parks and Denali highways. This circuit route was considered unacceptable by the resource agencies since it aggravated the control of public access. The seven remaining plans found to meet the selection criterion were plans 6, 11, 13, 14, 16, 17 and 18. Of these plans, plans 13, 16 and 18 in the North, South, and Denali corridors respectively were selected as being the most responsive plan in each corridor. The three plans are described below and the route locations shown in Figures 8.43 through 8.45. (i) Plan 13 'North' (see Figure 8.43) (ii) (iii) This plan utilizes a roadway from a railhead facility adjacent to the George Parks Highway at Hurricane to the Watana damsite following the north side of the Susitna Rivera A spur road, seven mi1es in length, would be constructed at a later date to service the Devil Canyon development. This route is mountainous and includes terrain at high elevations. In addition extensive sidehill cutting in the region of Portage Creek will be necessary, however construction of the road would not be as difficult as Plan 16. Plan 16 1 South 1 (see Figure 8.44) This route generally parallels the Susitna River, travelling west to east form a railhead at Gold Creek to the Devil Canyon damsite, and continues following a southerly loop to the Watana damsite. Twelve mi 1 es downstream of the Watana damsite a temporary low level crossing across the Susitna River wil be used until completion of a permanent bridge. A connecting road from the George Parks Highway to Devil Canyon, with a major high level bridge across the Susitna River is necessary to provide full road access to either site. The topography from Go)d Creek to Devil Canyon is mountainous and the route involves the most difficult construction of the three plans, requiring a 11Umber of sidehill cuts and the construction of two major bridges. To provide initial access to the Watana dams-ite this route presents the most difficult construction problems of the three routes and has the highest potential for schedule delays and related cost increases . Plan 18 'Denali-North' (see Figure 8.45) This route originates at a railhead in Cantwell, utilizing the existing Denali Highway to a point 21 miles east of the junction of the George Parks and Denali highways. A new road will be constructed from this point due south to the Watana damsite. The majority of the new road w)ll traverse 2-63 .. ' I I I relatively flat terrain which will allow construction using side borrow techniques, resulting in a minimum of disturbance to areas away from the alignment. This is the most easily constructed route for initial access to the Watana site. Access to the Devil Canyon development will consist primarily of a railroad extension from the existing Alaska Railroad at Gold Creek to a railhead facility adjacent to the Devil Canyon camp area. To provide access to the Watana damsite and the existing highway Watana damsite and the existing highway system a connecting road w~ll be constructed from the Devil Canyon railhead following a northerly loop to the Watana damsite. Access to the north side of the Susitna River will be attained via a high level suspension bridge constructed approximately one mile downstream of the Devil Canyon dam. In general the alignment crosses terrain with gentle to moderate slopes which will allow roadb2d construction without deep cuts. (f) Comparison of the Selected Alternative Plans To determine which access plan best accommodates both project related goals and the concerns of the resource agencies, Native organizations and affected communitites, the three selected alternative plans were subjected to a multi-disciplinary evaluation and comparison. The key issues addressed in this evaluation and comparison were: ( i ) Plan Costs For the development of access to the Watana site the Denali-North Plan has the least cost and the lowest probability of increased costs resulting from unforeseen conditions. The North Plan is ranked second. The North Plan has the lowest overall cost while the Denali-North has the highest. However, a lar~e portion of the cost of the Denali-North Plan would be incurrE~d more than a decade in the future. When converting costs to equivalent present value the overall costs of the Denali-North and the South plans are approximately equal. The costs of the three alternative plans cat~ be summarized as follows: Estimated To~~ Cost ($ x 106) Watana Devil Canyon Total D1 scounted Tot a 1 No~th (13) 241 \.. r· 127' 368 416 437 287 335 326 South (16) 312 Denali-North (18) 224 104 213 The costs are in terms of 1982 dollars and inrlude all costs associated with design, construction, maintenance and logistics. 2-64 • (ii) Schede1r~ The schedule for providing initial access to the Watana site was given prime consideration since the cost ramifications of a schedule delay are highly significant. The elimination of pre-license construction of a pioneer access road has resulted in the compression of on-site construction activities in the 1985-86 period. With the present overall project scheduling, should diversion not be comp1~ted prior to spring runoff in 1987, dam foundation preparation work will be delayed one year, and hence cause a delay to the overall project of one year. It has been estimated that the resultant increase in cost would likely be in the range of 100-200 million dollars. The access route that assures the quickest completion and hence the earliest delivery of equi?ment and material to the site has a distinct advantage. The forecasted construction period, including mobilization, for the three plans is: Denali-North North South 6 months; 9 months; and 12 months. It is evident that, with the Denali-North Plan, site activities can be supported at an earlier date than by either of the other routes. Consequently the Denali-North Plan offers the highest prcbability of meeting schedule and hence the least risk of project delay and increase in cost. The schedule for access in relation to diversion is shown for the three plans in Figure 8.46. (iii) Environment~l Issues Outlined below are the key environmental impacts which have been identified for the three routes. The specific mitigaton measures necessary to avoid, minimize or compensate for these impacts are discussed in Exhibit E. -Wildlife and Habitat The three selected alternative access routes are made up of five distinct wildlife and habitat segments: 1. Hurricane to Devil Canyon: This segment is composed almost entirely of productive mixed forest, · riparian, and wetlands habitats important to moose, furbearers, and birds. It includes three areas where slopes of over 30 percent will require side-hill cuts, all above wetland zones vulnerable to erosion related impacts. .. • I I I I > f} 2. Gold Creek to Devil ~anyon This segment is composed of mixed forest and wetland habitats, but includes less wetland habitat and fewer wetland habitat types than the Hurricane to Devil Canyon segment. Although this segment contains habitat suitable for moose, black bears, furbearers and birds it has the least potential for adverse impacts to wildlife of the five segments considered. 3. Devil Canyon to Watana (North Side): The following comments apply to both the Denali-North and North routes. This segment traverses a varied mixture of forest, shrub, and tundra habitat types, generally of medium to low productivity as wildlife habitat. It crosses the Devils and Tsusena Creek drainages and passes by Swimming Bear Lake which contains habitat suitable for furbearers. 4. Devil Canyon to Watana (South Side): This segment is highly varied with respect to habitat types, containing complex mixtures of forest, shrub, tundra, wetlands, and riparian vegetation. The western portion is mostly tundra and shrub, with forest and wetlands occurring along the eastern portion in the vicinity of Prairie Creek, Stephan Lake, and Tsusena and Deadman Creeks. Prairie Creek supports a high concentration of brown bears and the lower Tsusena and Deadman Creek areas support lightly hunted concentrations of moose and black bears. The Stephan Lake area supports high densities of moose and bears. Access development in this segment would probably result in habitat loss or alteration, increased hunting and human-bear conflicts. 5. Denali Highway to Watana: This segment is primarily composed of shrub anct tundra vegetation types, with little productive forest habitat present. Although habitat diversity is relatively low along this segment, the southern portion along Deadman Creek contains an important brown bear concentration and browse for moose. This segment crosses a peripheral portion of the range of the Nelchina caribou herd and there is evidence that as herd size increases, caribou are likely to migrate across the route and calve in the vicinity. Although it is not possible to predict with any certainty how the physical presence of the road itself or traffic will affect caribou movements, population size or productivity it is likely that a variety of site-specific mitigation measures will be necessary to protect the herd. 2-66 .. II ~ ,(1 Jil j ' ' Jl.' . . The three access plans are made up of the following combinations of route segments: North South Denali-North Segments 1 and 3 Segments 1, 2, and 4 Segments 2, 3, and 5 The North route has the least potential for creating adverse impacts to wildlife and habitat for it traverses or approaches the fewest areas of productive habitat and zones of species concentration or movement. The wildlife impacts of the South Plan can be expected to be greater than those of the North Plan due to the proximity of the route to Prairie Creek, Stephan Lake and the Fog Lakes, which currently support high densities of moose and black and brown bears. In particular Prairie Creek supports what may be the highest concentration of brown bears in the Susitna Basin. Although the Denali-North Plan has the potential for disturbances of caribou, brown bear and black bear concentrations and movement zones, it is considered that the potential for adverse impacts with the South Plan is greater o Fisheries All three alternative routes would have direct and indirect impacts on the fisheries. Direct impacts include the affects on water quality and aquatic habitat whereas increased angling pressure is an indirect impact. A qualitative comparison of the fishery impacts related to the alternative plans was undertaken. The parameters used to assess impacts along each route included: the number of streams crossed, the number and length of lateral tr-ansits (i .. e., where the roadway parallels the streams and runoff from the roadway can run directly into the stream), the number of watersheds affected, and the presence of resident and anadromous fish . The three access plan alternatives incorporate combinations of seven distinct fishery segments. 1. Hurricane to Devil Canyon: Seven stream crossings .will be required along this route, including Indian River which is an important salmon spawning river. Both the Chulitna River watershed and the Susitna River watershed are affected by this route. The increased access to Indian River will be an important indirect impact to the segment. Approximately 1.8 miles of cuts into banks greater than 30 degrees occur along this route requiring erosion control measures to preserve the water quality and aquatic habitat. 2-67 .. ·, "' I I' . I I '~ l t L l t 2. Gold Creek to Devil Canyon: This segment crosses six streams and is expected to have minimal direct and indirect impacts. Anadromous fish spawning is likely in some streams but impacts are expected to be minimal. Approximately 2.5 miles of cuts into banks greater than 30 degrees occur in this section. In the Denali-North Plan, this segment would be railroad whereas in the South Plan it would be road. 3. Devil Canyon to Watana (North Side, North Plan): This segment crosses twenty streams and laterally transits four rivers for a total distance of approximately twelve miles. Seven miles of this 1 ateral transit parallels Portage Creek which is an important salmon spawning area. 4. Devil Canyon to Watana (North Side, Denali-North Plan): The difference between this segment and segment 3 described above is that it avoids Portage Creek by traversing through a pass four miles to the east. The number of streams crossed is consequently reduced to twelve, and the number of lateral transits is reduced to two with a total distance of four miles. 5. Devil Canyon to Watana (South Side): The portion between the Susitna River Ci"ossing and Devil .canyon requires nine steam crossings, but it is unlikely that these contain significant fish populations. The portion of this segment from Watana to the Susitna River is not expected to have any major direct impacts, however, increased angling pressure in the vicinity of Stephan Lake may result cue to the proximity of the access road. The segment crosses both the Susitna and the Talkeetna watershed. Seven miles of cut into banks of greater than 30 degrees occur in this segment. 6. Denali Highway to Watana: The segment from the Denali Highway to the Watana damsite has twenty-two stream crossings and passes from the Nenana into the Susitna watershed. Much of the route crosses or is in proximity to seasonal grayling habitat and runs parallel to Deadman Creek for nearly ten miles. If recruitment and growth rates are low along this segment it is unlikely that resident populations could sustain heavy fishing pressure. Hence, this segment has a high potential for impacting the local grayling population. 2-68 '] I I I t f g 7. Denali Highway: The Denali Highway from Cantwell to the Watana access turnoff will require upgrading. The upgrading will 1nvolve only minor realignment and negligible alteration to present stream crossings. The segment crosses eleven streams and laterally transits two rivers for a total distance of five miles. There is no anadromous fish spawning in this segment and little direct or indirect impact i s expected. The three alternative access routes are comprised of the following segments: North South Denali-North Segments 1 and 3 Segments 1, 2, and 5 Segments 2, 4, 6 and 7 The Denali-North Plan is likely to have a significant direct and indirect impact on grayling fisheries given the number o·f stream crossings, lateral transits, and watershed affected. Anadromous fisheries impact will be minimal and will only be significant along the railroad spur between Gold Creek and Devil Canyon. The South Plan is likely to create significant direct and indirect impacts at Indian River, which is an important salmon spawning river. Anadromous fisheries impacts will also occur in the Gold Creek to Devil Canyon segment as for the Denali-North Plan. In addition indirect impacts may occur in the Stephan Lake area. The North Plan, like the South Plan may impact salmon spawning activity in Indian River. Significant impacts are likely along Portage Creek due to water quality impacts through increased eroston and due to indirect impacts such as increased angling pressure. ~~ith any of the selected plans, direct and indirect effects can be minimized through proper engineering design and prudent management. Criteria for the development of borrow areas and the design of bridges and culverts for the proposed access plan together with mitigation recommendations are discussed in Exhibit E. (iv) Cultural Resources A level one cultural resources survey was conducted over a large portion of the three access plans. The segment of 2-69 I I I t (v) the Denali-North Plan between the Watana damsite and the Denali Highway traverses an area of high potential for cultural resc.Jrce sites. Treeless areas along this segment lack appreciaole soil desposition, making cultural resources visible and more vulnerable to secondary impacts. Common to both the Denali-Nor.:h and the North Plan is the segment on the north side of the Susitna River from the Watana damsite to where the road parallels Devils Creek. This segment is also largely treeless making it highly vulnerable to secondary impacts. The South Plan traverses less terrain of archaeological importance than either of the other two routes. Several sites exist along the southerly Devil Canyon to Watana segment, however, since much of the route is forested these sites are less vulnerable to secondary impacts. The ranking from the least to the highest with regard to cultural resources impacts is South, North, Denali-North. However, impacts to cultural resources can be fully mitigated by avoidance, protection or salvage; consequently, this issue was not critical to the selection process. Socioeconomics Socioeconomic impacts on the Mat·-Su Borough as a whole would be similar in magnitude for all three plans. However~ each of the three plan~ ~ffects future socioeconomic conditions in differ-1g degrees in certain areas and communities. The important differences affecting specific communities are outlined below. -Cantwell: The Denali-North Plan would create significant increases in population, local employment, business activity, housing and traffic. These impacts result because a railhead facility would be located at Cantwell and b~cause Cantwell would be the nearest community to the Watana damsite. Both the North and South Plans would impact Cantwell to a far lesser extent. -Hurricane: The North Plan would significantly impact the Hurricane area since currently there is little population, employment, business activity or housing. Changes in socioeconomic indicators for Hurricane would be less under the South Plan and considerably less under the Denali-North plan. 2-70 ·.1····· j ' 1 .. I I I I I (vi) -Trapper Creek and Talkeetna: Trapper Creek would experience slightly larger changes in economic indicators with the North Plan than under the South or Denali-North Plans. The South Plan would impact the Talkeetna area slightly more than the other two plans. -Gold Creek: With the South Plan a railhead facility would be developed at Gold Creek creating a significant increase in socioeconomic indicators in this area. The Denali-North Plan includes construction of a railhead facility at the Devil Canyon site, which would create impacts at Gold Creek, but not to the same extent as the South Plan. Minimal impacts would result in Gold Creek under the North Plan. The affected public's responses to these potential changes are mixed. The people of Cantwell are generally in favor of some economic stimulus and development in their community. Residents of Trapper Creek and Talkeetna have indicated that rapid, uncontrolled change is not desired. This and other feedback to date indicates that the Denali-North Plan will come closest to creating socioeconomic changes that are acceptable to or desired by landholders and residents in the potentially impacted areas and communities. Preferences of Native Organizations .-:::& The Tyonek Native Corporation, Cook Inlet Region Inc. (CIRI) and the CIRI Village residents all prefer the South Plan since it provides full road access to their lands south of the Susitna River. The Ahtna Native Region Corporation and the Cantwell Village Corporation support the Denali-North Plan. None of the Native Organizations support the North Plan. (vii) Relationship to Current Land Stewardships, Uses and Plans Much of the land required for project development has been or may be conveyed to Native organizations. The remaining lands are generally under state and federal control. The South Plan traverses more Native-selected lands than either of the other two routes, and although present land use is low, the Native organizations have expressed an interest in potentially deveiop·ing their lands for mining, recreation$ forestry or residential use. 2-71 • I . . . I I (g) I I I (h) The other land management plans that have a large bearing on access development are the Bureau of Land Management•s (BLM) recent decision to open the Denali Planning Block to mineral exploration, and the Denali Scenic Highway Study being initiated by the Alaska Land Use Council. The Denali Highway to Deadman Mountain segment of the Denali-North Plan would be compatible with BLM•s plans. During the construction phase of the project the Denali-North Plan could create conflicts with the development of a Denali Scenic Highway; however, after construction the access road and project facilities could be incorporated into the overall Scenic Highway planning. By providing public a~~ess to a now relatively inaccesible, semi-wilderness area, conflict may be imposed with wildlife habitats necessitating an increased level of wildlife and people management by the various resource agencies. In general, however, non~ of the plans will be in major conflict with any present federal, borough or Native management plans. Summary In reaching the decision as to which of the three alternative access plans was to be recommended, it was necessary to evaluate the highly complex interplay that exists between the many issues involved. Analysis of the key issues indicates that no one plan satisfied all the selection criteria nor accommodated all the concerns of the resource agencies, Native organizations and public. Therefore, it was necessary to make a rational assessment of tradeoffs between the sometimes conflicting environmental concerns of impacts on fisheries, wildlife, socioeconomics, land use and recreational opportunities on the one hand, with project cost, schedule, construction risk and management needs on the other. With all these factors in mind, it should be emphasized that the primary purpose of access is to provide and maintain an uninterrupted flow of materials and personnel to the damsite throughout the life of the project. Should this fundamental objective not be achieved, significant schedule and budget overruns will occur. Final Selection of Plan (i) Elimination of 'South Plan• The South route, Plan 16, was eliminated primarily because of the construction difficulties associated with building a major low level crossing twelve miles downstream of the Watana damsite. This crossing would consist of a floating 2-72 I I I I I I I_ i t L or fixed temporary bridge which would need to be removed prior to spring breakup during the first three years of the project, (the time estimated for completion of the permanent bridge). This would result in a serious interruption in the flow of materials to the site. Another drawback is that floating bridges require continual maintenance and are generally subject to more weight and dimensional limitations than permanent structures. A further limitation of this route is that for the first three years of the project all construction work must be supported solely from the railhead facility at Gold Creek. This problem arises because it will take an estimated three years to complete construction of the connecting road across the Susitna River at Devil Canyon to Hurricane on the George Parks Highway. Limited access, such as this, does not provide the flexibility needed by the project management to meet contingencies and control costs and schedule. Delays in the supply of materials to the damsite, caused by either an interruption of service of the railway system or the Susitna River not being passable during spring breakup, could result in significant cost impacts. These factors, together with the realization that the South Plan offers no specific advantages over the other two plans in any of the areas of environmental or social concern, led to the South Plan being eliminated from further consideration. {ii) Schedule Constraints The choice of an atcess plan thus narrowed down to the North, and Denali-North Plans. Of the many issues addressed during the·evaluation process, the issue of "schedule" and 11 SChedule risk" was determined as being the most important in the final selection of the recommended plan. Schedule plays such an important role in the evaluation process because of the special set of conditions that exist in a sub arctic environment. Building roads in these regions involves the consideration of many factors not found elsewhere in other environments . Specifically, the chief concern is one of weather, and the consequent short duration of the construction season. The roads for both the North and Denali-North plans will, for the most part, be constructed at elevations in excess of 3,000 feet. At these elevations the likely time available for uninterrupted construction in a typical year is 5 months, and at most 6 months. 2-73 ~ I I I I I I I I (iii) The foreca~~ted construction period including mobilization is 6 months for the Denali-North Plan and 9 months for the North. At first glance a difference in schedule of 3 months does nat seem great, however when considering that only 6 months of the year are available for construction the additional 3 months become highly significant. If diversion is not achieved prior to spring runoff in 1987: dam foundation preparation work will be delayed one year, and hence cause a delay to the overall project of one yea~·. Cest Impacts_ The increase in costs resulting from a one year delay have been estimated to be in the range of 100-200 million. This increase includes; the financial cost of investment by spring of 1987, the financial costs of rescheduling work for a one year delay, and replacement power costs. ( i v) Summary The Denali-North Plan has the highest probability of meeting schedule and least risk of increase in project cost for two reasons. First it has the shortest construction schedule (six months). Second is that winter construction, although difficult, would cause no significant delay for the route traverses relatively flat terrain for its entire length. In contrast the North route is mountainous and involves extensive sidehill cutting, especially in the Portage Creek area. Winter construction along sections such as this would presert major problems and enhance the probability of schedule delay. (v) Plan Recommendation It is recommended that the Denali-North route be selected so as to ensure completion of initial access to the Watana damsite by the end of the first quarter of 1986, for it is considered that the risk of significant cost overuns is too high with any other route. (vi) Environmental Concerns -Recommended Plan The m~in disadvantage of the Denali-North route is that it has a higher potential for adverse environmental impacts than the North route alternative. These impacts have been identified and following close consultation with environmental subconsultants many of the impacted areas have been avoided by both careful alignment of the road, 2-74 . . . . ... ' . . ' 4,-I .1> ' "', ·"'" ' " • ' I ' . . • , • II \ # • .. • I . . I I I I I and the development of design c~iteria which do not detract from the semi-wilderness charac:2r of the area. Some environmental impacts and conf 1 cts are unavoidable however, and where these impac~; occur 5 speciric mitigation measures have been developed tt reduce them to a minimum. These measures are outlined in jetail within the relevant sections of Exhibit E . 2.7 -Selection of Transmission Facilitie~ The objective of this section is to descr te the studies performed to select a power delivery system from the S1 sitna River basin generating plants to the major load centers in Anchorage and Fairbanks. This sys- tem will be comprised of transmission lines, substations, a dispatch center, and means of communicationsv The major topics of the transmission studies include: -Electric system studies; -Transmission corridor selection; -Transmission route selection; -Transmission towers, hardware and conductors; -Substations; and -Dispatch center and communications. -· (a) Elec~ric System Studies Transmission planning criteria were developed to ensure the design of a reliable and economic electrical power system, with compont.~nts rated to allow a smooth transition through early project stages to the ultimate developed potential. Strict application of optimum, long-term criteria would require the installation of equipment with ratings larger than necessary at excessive cost. In the interest of economy and long-term system performance, these criteria were temporarily relaxed during the early development stages of the project. Although allowing for satisfactory operation during early system development, final system parameters must be based on the ultimate Susitna potential. The criteria are intended to ensure maintenance of rated power flow to Anchorage and Fairbanks during the outage of any single line or transformer element. The essential features of the criteria are: -Tota·l power output of Sus itna to be delivered to one or two stations at Anchorage and one at Fairbanks; - 11 Breaker-and-a-half" switching station arrangements; 2-75 J 1 J j J .'I ll J ' ' :j ;J J '{J • -Overvoltages during line energizing not to exceed specified limits; -·System voltages to be within established limits during normal operation; Power delivered to the loads to be maintained and system voltages to be kept within established limits for system operation under emergency conditions; -Transient stability during a 3-phase line fault cleared by breaker action with no reclosing; and -Where performance limits are ex~eeded, the most cost effective corrective measures are.to be takene (i) Existing System Data Data compiled in a report by Commonwealth Associates Inc. (16) has been used for preliminary transmission system analysis. Other system data were obtained in the form of single-line diagrams from the various utilities. (ii) Power Transfer Requirements The Susitna transmission system must be designed to ensure the reliable transmission of power and energy generated by the Susitna Hydroelectric Project to the load centers in the Railbelt area. The power transfer requirements of this transmission system are determined by the following factors: -System demand at the various load centers; -Generating capabilities at the Susitna project; and -Other generation available in the Railbelt area system. Most of the electric load demand in the Railbelt area is located in and around two main centers: Anchorage and Fairbanks. The largest load center is Anchorage, with most of its load concentrated in the Anchorage urban area. The second largest load center is Fairbanks. Two small load centers (Willow and Healy) are located along the Susitna transmission route. The only other significant load centers in the Railbelt region are Glennallen and Valdez~ however, their combined demand is expected to be less than 2 percent of the total Railbe1t demand in the foreseeable future. A survey of past and present load demand levels as well as various forecasts of future trends ~~'rlicates these approximate load levels at the various c~ ~,?. • I I j . .J Load Area Anchorage -Cook Inlet Fairbanks -Tanana Valley Glennallen -Valdez Percent of Total Rai lbelt Load 78 20 2 Consider·ing the geographic location and the currently projected magnitude of the total load in the area, transmission to Glennallen-Valdez is not likely to be economical in the foreseeable future. If it is ever to be economical at all, it would likely be a direct radial extension, either from Susitna or from Anchorage. In either case, its relative magnitude is too small to have significant influence on either the viability or development characteristics of the Susitna project or the transmission from Susitna to the Anchorage and Fairbanks areas. Accordingly, it has been assumed for study purposes that approximately 80 percent of the generation at Susitna will be transmitted to the Anchorage area and 20 percent to Fairbanks. To account for the uncertainties in future local load growth and local generation development, the Susitna transmission system was designed to be able to transmit a maximum of 85 percent of Susitna generation to Anchorage and a maximum of 25 percent to Fairbanks. The potential of the Susitna Hydroelectric Project is expected to be developed in three or four stages as the system load grows over the next two decades. The transmission system must be designed to serve the ultimate Susitna development, but staged to provide reliable transmission at every intermediate stage. Present plans call for three stages of Susitna development: 680 MW at Watana in January 1994 followed by an additional 340 MW in July 1994; and, 600 MW at Devil Canyon in 2002. Development of other generation resources could alter the geographic load and generation sharing in the Railbelt, depending on the location of this development. However, current studies indicate that no other very large projects are likely to be developed until the full potential of the Susitna project is utilized~ The proposed transmission configuration and design should, therefore, be able to satisfy the bulk transmission requirements for at least the next two decades. The next major genera~lon development after Susitna will then require a transmission system determined by its own magnitude and location. The resulting power transfer requirements for the Susitna transmission system are indicated in Table B~35. 2-77 l r I I J J j j {iii) Transmission Alternatives Because of the geographic locdtion of the various centers, transmission from Susitna to Anchorage and Fairbanks will result in a radial system con~'iguration. This allows significant freedom in the choice of transmission voltages, conductors, and other parameters for the two line sections, with only limited dependence between them. Transmission alternatives were developed for each of the two system areas, including voltage levels, number of circuits required, and other parameters, to satisfy the necessary transmission requirel-iients of each area. To maintain a consistency with standard ANSI voltages used in other parts of the United States, the following voltages were considered for Susitna transmission: o Watana to Devi 1 Canyon and on to Anchorag1e: o Devil Canyon to Fairbanks: -Susitna to A~~horage 500 kV or 345 kV 345 kV or 230 kV Transmission at either of two different voltage levels {345 kV or 500 kV) could reasorably provide the necessary power transfer capability over the distance of approximately 140 miles between Devil Canyon and Anchorage. The required transfer capability of 1,377 MW is 85 percent of the ultimate generating capacity of 1,620 MW. At 500 kV, two circuits would provide more than adequate capacity. At 345 kV, either three circuits uncompensated or two circuits with series compensation are required to provide the necessary reliability for the single contingency ou·cage criterion .. At lower voltages, an excessive number of parallel circuits are required, while above 500 kV, two circuits are still needed to provide service in the event of a line outage. -Susitna to Fairbanks Applying the same reasoning used in choosing the transmission alternatives to Anchurage, two circuits of either 230 kV or 345 kV were chosen for the section from Davil Canyon to Fairbanks. The 230 kV alternative requires series compensation to satisfy the planning criteria in case of a line outage. 2-78 • I ! ,·' I ~;_, ,, -Total System Alternatives The transmission section alternatives mentioned above were combined into five realistic total system alternatives. Three of the five alternatives have different voltages for the two sections. The principal parameters of the five transmission system alternatives analyzed in detail are as follows: Susitna to Anchorage Susitna to Fairbanks Number of Number of Alternative Circuits Voltage Circuits Volta!e ( kV) (k( 1 2 345 2 345 2 3 345 2 345 3 2 345 2 230 4 3 345 2 230 5 2 500 2 230 Electric system analyses, including simulations of line energ1z1ng, load flows of normal and emergency operating conditions, and transient stability performance, were carried out to determine the technical feasibility of the various alternatives. An economic comparison of transmission system life cycle costs was carried out to evaluate the relative economic merits of each alternative. All five transmis~1on alternatives were found to have acceptable performance characteristics. The most significant difference was that single-voltage systems (345 kV, Alternatives 1 and 2) and systems without series compensation (Alternative 2) offered reduced complexity of design and operation and therefore were likely to be marginally more reliable. The present-worth life cycle costs of Alternatives 1 through 4 were all within one percent of each other. Only the cost of the 500/230 kV scheme (Alternative 5) was 14 percent aoove the others. A surrmary of the life cycle cost analyses for the various alternatives is shown in Table 8.36. A technical and economic comparison was also carried out to determine possible advantages and disadvantages of HVDC transmission, as compared to an ac system, for transmitting )usitna power to Anchorage and Fairbanks. HVDC transmission was found to be technically and operationally more complex as well as having higher life cycle costs. 2-79 • ., I L (iv) Confiauration at Generation and Load Centers Interconnections between generation and load centers and the transmission system were developed after reviewing the existing system configurations at both Anchorage and Fairbanks as well as the possibilities and current development plans in the Susitna, Anchorage, Fairbanks, Willow, and Healy areas. Susitna C9nfiguration Preliminary development plans indicated that the first project to be constructed would be Watana with an initial installed c~pacity of 680 MW, to be increased to 1020 MW in the second development stage~ The next project~ and the last to be considered in this study, would be Devil Canyon, with an installed capacity of 500 MW. ~itching at Willow Transmiss ;on from Susitna to Anchorage is facilitated by the introduction of an intermediate switching station. This has the effect of reducing line energizing overvoltages and reducing the impact of line outagP~ on system stability. Willow is a suitable locatior1 ~JY' this intermediatr switching station; in additio'. it would make it possible to supply local load when tt.1s is justified by development in the area. This local load is expected to be less than 10 percent of the total Railbelt area system load, but the availability of an EHV line tap would definitely facilitate future power supply. Switching at Healy A switching station at Healy was considered early in the analysis but was found to be unnecessary to satisfy the planning criteria. The predicted load at Healy is small enough to be supplied by local generation and the existing 138 kV transmission from Fairbanks. -Anchorage Configuration Analysis of system configuration, distribution of loads, and development in the Anchorage area 'led to the conclusion that a transformer station near Palmer would be of little benefit. Most of the major loads are concentrated in and around the urban Anchorage area at 2-80 .. • '] J ;-;1 < _, ·-'t J l < r- I I l' the mouth of Knik Arm. In order to reduce the length of subtransmission feeders, the transformer stations should be located as close to Anchorage as possible. The routing of transmission into Anchorage was chosen from the following three possible alternatives: o Submarine Cable Cro·ssing From Point MacKenzie to Point Woronzof This would require transmission thr-ough a very heavily developed area. It would also expose the cables to damage by ships• anchors, which has been the experience with existing cables, resulting in questionable transmission reliability. - o Overland Route North of Knik Arm via Palmer This may be most economical in terms of capital cost in spite of the long distance involved. However, approval for this route is unlik~'ly since overhead transmission through this developed area is considered environmentally unacceptable. A longer overland route around the developed area is considered unacceptable because of the mountainous terrainc o Submarine Cable Crossing of Knik Arm, In the Area of Lake Lorraine and Six M11 e Creek This option, approximately parallel to the new 230 kV cable under construction for Chugach Electric Association (CEA), includes some 3 to 4 miles of su6marine cable and requires a high capital cost. Since the area is upstream from the shipping lanes to the port of Anchorage, it will result in a reliable trapsmission link, and one that does not have to cross environmentally sensitive conservation areas. The third alternative is clearly the best of the three options. With this configuration a differeh" option is possible for the submarine cable crossing. To reduce cable costs the crossing could be constructed with two cable circuits plus one spare phase. This option requires a switching station at the west terminal of Knik Arm. A switching station at the west terminal would clearly require increased costs and complications for constru~tion and operation as a result of poor accessG 2-81 • .. " _ .. _ -4-,. ·~ ......:::;....__ r--•-.w·~'-• ___ ....:; .. ~·-, ~ ··~•·-···-~ ~; I I I I I ,.,_:, .~·.;:_a ~~··.· ):.::_:__.~ '!···· .. ' __:_"~---- Fairbanks Configuration Susitna power for the Fairbanks area is recommended to be delivered to a single EHV/138 kV transformer station located at Ester. No alternatives were given detailed consideration. (b) Corridor Selection {i) Methodology Development OT the proposed Susitna project will require a transmission system to deliver electric power to the Railbelt area~ The building of the Anchorage to Fairbanks Intertie system will result in a defined corridor· and route for the Susitna transmission lines between Willow and Healy.. Therefore, three areas require study for corridor selection: the northerr area to connect Healy with Fairbanks; the central area to connect the Watana and Devil Canyon dams ites with the Interti e; and the southern area to connect Willow with Anchorage. Using the selection criteria discussed below, corridors 3 to 5 miles wide were selected in each of the three study areas. These corridors were then evaluated to determine which ones met the more specific screening criteria. This screening process resulted in one corridor in each area being designated as the recommended corridor for the transmission line. (ii) Selection Criteria Since the corridors studied range in width from three to five miles, the base criteria had to be applied in broad terms. The study also indicated that the criteria listed for technical purposes could reappear in the economic or environmental classification. The technica·. criteria were defined as requirements for the normal and ~afe performance of the transmission system and its reliability. The selection criteria are in three categories, technical, economic and environmental& The criteria are listed in Table 8.37 .. ·(iii) Identification of Corridors As discussed previously, the Susitna transmission line corridors studied are located in three geographical areas; namely: 2-82 • .. I I I' 'I I I i - -The southern study area between Willow and Anchoragee -The central study area between Watana, Devi 1 Canyon, and the Intertie. -The northern study area between Healy and Fairbankso (iv) Description of Corridors Figures 8.47 through Be49 portray the corridors evaluated in the southern, central, and northern study areas, respectively. For purposes of simplification, only the centerline of the three-to-five-mile-wide corridors are shown in the figures. In each of the three figures, each corridor under consideration has been identified by the use of letter symbols. The various segment intersections and the various segments, where appropriate, have been designated. Thus, segments in each of the three study areas can be separately referenced. Furthermore, the segments are joined together to form corridors~ For example, in the northern study area Corridor ABC is composed of Segments AB and BC. The alternative corridors selected for each study area are described in detail in the following paragraphs. In addition, Tables 8.38, 8.39 and B.40 contain detailed environmental data for each corridor segment. -Southern Study Area o Corridor One -Willow to Anchorage via Palmer Corridor ABC's consisting of Segments AB and BC', begins at the intersection with th~ Intertie in the vicinity of Willow. From here, the corridor travels in a southeasterly direction, crossing wetlands, Willow Creek, and Willow Creek Road before turning slightly to the southeast following the drainage of Deception Creek. The topography in the vicinity of this segment of the corridor is relatively flat to gently rolling with standing water and tall-growing vegetation in the vicinity of the creek drainages. At a point northwest of Bench Lake, the corridor turns in an easterly direction crossing the southern foothills of the T~lkeetna Mountains. The topography here is gently to mo~erately rolling with shrub-to tree-sized vegetation occurring throughout. As the corridor approaches the crossing of the Little Susitna River, it turns and heads southeast again, crossing the little Susitna River and Wasilla Fishhook Road .. 2-83 • "· ~ .::::. . ' ' ' '-......_ '.' r I 'I Passing near Wolf Lake and Gooding Lake, the corridor then crosses a secondary road, some agricultural lands, State Route 3, and the Glenn Highway, before intersecting existing transmission lines south of Palmer. In the vicinity of the Little Susitna River, the topography is gently rolling. As the corridor travels toward Palmer~ the land flattens, more lakes are present, and some agricultural development is occurring. After crossing the Glenn Highway, the corridor passes through a residential area before crossing the broad floodplain of the Matanuska River. Just west of Bodenburg Buttes the corridor turns due south through more agricultural land before crossing the Knik River and eventually connecting with the Eklutna Power Station. All of the land south of Palmer is very flat with some agricultural development. Just south of Palmer, the proposed corridor intersects existing transmission facilities and parallels or replaces them from a point just south of Palmer, across the river, and into the vicinity of the Ekl utna Power House. From her·e into Anchorage, the corridor as proposed would parallel existing facilities, crossing near or through the communities of Eklutna, Peters Creek, Birchwood, and Eagle River by using one of the two existing transmission line ri ghts·-of-way in this area. The 1 and here is flat to gently rolling with a great deal of t·esidential development. This corridor segment is the most easterly of the three considered in the southern study area and avoids an underw~ter crossing of Knik Arm. o Cor~idor Two -Willow to Point MacKenzie via Red Shirt Lake Corridor ADFC, consisting of Segments ADF and FC, commences again at the point of intersection with the Intertie in the vicinity of Willow; but immediately turns to the southwest, first crossing the railroad, then the Parks Highway, then Willow Creek just west of Willow. The land in the vicinity of this part of the segment is very flat~ with wetlands dominating the terrain. Southwest of Florence Lake, the proposed corridor turns, crosses Rolly Creek, and heads nearly due south, passing through extensive wetlands west and wetlands west and south of Red Shirt Lake .. The corridor in this area parallels existing tractor trails crossing very flat lands with significant 2-84 .. .. " I I I I i) amounts of tall-growing vegetation in the better drained locations. Northwest of Yohn Lake, the corridor segment turns to the southeast, passing Yohn Lake and My Lake before crossing the Little Susitna River. Just south of My Lake, the corridor turns in a generally southerly direction, passing Middle Lake, and east of Horseshoe Lake before finally intersecting the existing Beluga 230 k V transmission 1 i ne at a spot just north of MacKenzie Point. From here, the corridor parallels MacKenzie Point's existing transmission facilit·ies before crossing under Knik Arm to emerge on the easterly shore of Knik Arm in the vicinity of · Anchorage. The land in the vicinity of this segment is extremely flat and very wet, supporting dense stands of tall-growing vegetation on any of the higher or better drained areasu o Corridor Three -Willow to Point MacKenzie via Lynx lake Corridor AEFC is very similar to and is a derivation of Corridor ADFC; it consists of Segments AEF and FC. This corridor also extends to the southwest of Willow. West of the Parks Highway, however, just north of Willow Lake, this corridor turns and travels southwest of Willow and east of Long Lake, passiny between Honeybee Lake and Crystal Lake. The corridor then turns southeastward to pass through wetlands east of Lynx Lake and Butterfly Lake before crossing the Little Susitna River. The land is well developed in this area. It is very flat and, while it is wet, also supports dense stands of tall growing vegetation on the better drained sites. Corridor Three rejoins Corridor Two at a point south of My Lake. -Central Study Area The central study area encompasses a broad area in the vicinity of the damsites. From Watana, the study area extends to the north as far as the Denali Highway and to the south as far as Stephan Lake. From this point westward, the study area encompasses the foothills of the Alaska Range and, to the south, the foothills of the Talkeetna Mountains. Included in this study area are 1 ands under consideration by the Interti e Project investigators. The ~lternative corridors would connect both Devil Canyon and Watana dams with the Intertie at 2-85 • .. one of four locations, which are identified in Figure R .48. As for the southern study area, individual corridor segments are listed in the text. This is to aid the render both in determining corridor locations in the figures and in examining the environmental inventory data listed for each segment in Tables 8.38, 8.39, and 8.40. o Corridor One-Watana to Intertie via South Shore, 'Susitna River Corridor ABCD consists of three segments: AB, BC, and CD. This corridor originates at the ~Jatana Dam site and fo 11 ows the southern boundary of the river at an elevation of approximately 2,000 feet from Watana to Devil Canyon. From Devil Canyon, the corridor continues along the southern shore of the Susitna River at an elevation of about 1,400 feet to the point at which it connects with the Intertie, assuming the Intertie follows the railroad corridor. The land surface in this area is relatively flat, though incised at a number of locations by tributaries to the Susitna River. The relatively flat hills are covered by discontinuous stands of dense, tall-growing vegetation. o Corri dar Two -Watana to Intert ie vi a Stephan Lake ABECD, the second potential corridor, is essentially a derivation of Cortidor One and is formed by replacing Segments BC with BEC. Originating at Point B, Corridor Segment BEC leaves the river and generally parallels one of the proposed Watana Dam access road corridors. This corridor extends southwest from the river, passing near Stephan Lake to a point northwest of Oaneka Lake. Here the route turns back to the northwest and intersects Corridor One at the Devil Canyon Dam site. The terrain in this area!) again, is gently rolling hills with relatively flat benches. Vegetation cover ranges from sparse at the higher elevations to dense along the river bottom and along gentler slopes of the Susitna River and its tributaries. 2-86 i u I I l Jl .1.1 I o Corridor Three ·, ;~at ana to Intert i e vi a North Shore, Susitna River Corridor Tnree (AJCF), located on the north side of -the river, consists of Segments AJ and CF. Starting at the Watana Dam site, the corridor crosses Tsusena Creek and heads westerly, following a small drainage tributary to the Susitna River. Once crossing Devil Creek, the corridor passes north and west of High Lake. · The corridor stays below an elevation of 3,700 feet as it crosses north of the High Lak.e area, east of Devi 1 Creek, on its approach to Devil Canyon. From Devil Canyon, the corridor again extends to the west, crossing Portage Creek and intersecting the Intertie in the vicinity of Indian River. In the drainages, to elevations of ~bout 2~000 feet, tree heights range to 60 feet. Between Devil Creek and Tsusena Creek, however, at the higher elevations, very little vegetation grows taller than three fee~. Once west of Devil Creek, discontinuous areas of tall-growing vegetation exist. o Corridor Four -Watana to Intertie tia Devil Creek Pass/East Fork Chulitna River Another means of connecting the two dam schemes with the Intertie is to follow Corridor One from Watana to Devil Canyon and then exit the Devil Canyon project to the north (ABCJHI). This involves connecting Corridor Segments AB, BC, CJ, HJ, and HI. With this alternative, the corridor extends northeast at Devil Canyon past High Lake to Devil Creek drainage, From there, it moves northward to a point north of the south boundary of the Fairbanks Meridian. The corridor then follows the Portage Creek drainage beyond its point of origin to a site within the Tsusena Creek drainage. Likewise, it follows the Tsusena Creek drainage to a point near Jack River, at which point it parallels this drainage into Caribou Pass. From Caribou Pass, the corridor turns to the west, following the Middle Fork Chulitna River until meeting the Intertie in the vicinity of Summit Lake. While along much of this corridor the route follows river valleys, the plan also requires crossing high mountain passes in rugged terrain. This is especially true in the crossing between Portage Creek and Tsusena Creek drainages, where elevations of over 4,600 feet are involved. Tall-growing vegetation is restricted to the lower elevations along the river drainages with 2-87 I I J J -.. '.·>'-. ·---~·-•' ·: . ~ .. '"~ ~:_~:;~ ~~. 1 ittl e other than 1 ow-growing fm--bs and shrubs present at higher el ev at ions. o Corridor Five -Watana to Intertie via Stephan Lake and the East Fork Chulitna River A variation of Corridor Four, Corridor Five (ABECJHI) rep 1 aces Segment BC with Corri dar Segment BEC (of Corridor Two) with the previously described corridor. This results in a corridor that extends fr-om the Watana Dam site southwesterly to the vicinity of Stephan Lake, and from Stephan Lake into the Devil Canyon Dam site.. From Devil Canyon to the Intertie, the corridor follows the Devil Creek, Portage Creek, and Middle Fork Chulitna drainages previously mentioned. As before, ~he corridor crosses rolling terrain throughout the length of the paralleled drainages, with some confined, higher elevation passes encountered between Portage Creek and Tsusena Creek .. o Corridor Six -Devil Canyon to the Intertie via 1susena Creek/Chulitna River -Another option (CBAHI) for connecting the dam projects to the Intertie involves conn.ecting Devil Canyon and Watana along the south shore of the Susitna River vi a Corridor Segment CBA, then exiting Watana to the north on Segments AH and HI along Tsusena Creek to follow this drainage to Caribou Pass o The corridor" then contains the previously described route along the Jack River and ~1iddle Fork Chulitna until connecting with the Intertie near Summit Lake. The terrain in this corridor proposal would be of moderate elevation with some confined, higher elevation passes between the drainages of Tsusena Creek and the Jack Ri ver,o o Corridor Seven -Devil Canyon to Intertie via Stephan Lake and Chulitna River This alternative uses CorridOt"' Six but replaces Segment BC with Segment BEC from Corridor Two. This route would thus be designated CEBAHI. Terrain features are as described in Corridors Two and Six. o Corridor Eight -Devil Canyon to Intertie via Deadman/ Brush~ana Creeks: and [}en a 1 i Hi ghwa.y_ · Yet another option to the previously described corridors is the interconnection of Devil Canyon with Wat ana vi a Corridor One (Segment CBA), with a segment 2-88 .. . I I J 1 t hen extendin g from Watana north ea st er ly al ong the De adman Creek drainage (Segment AG ). The segment proceed 5 north of Deadman Lake and Deadman Mountai n, then turns to the west and intersects the Brushkana Creek dra i nage . It then follows Brushkana Creek north to a point east of the Kana Bench Mark. This segment of the corridor would parallel one of t he proposed access roads. From there, the corr ;dor turns west, generally parallel to the Denal i Highway , to the point of interconnection with the Intertie in the vicinity of Cantwell. The area encompasses rolling hills with modest elevation changes and some forest cover, especially at the lower elevations. o Corridor Nine -Devil Canyon to Intertie via Stephan Lake and Denali Highway Corridor Nine (CEBAG) is exactly the same as Corridor Eight with the exception of Corridor Segment BEC, utilized to replace Segment BC. Each combination of segments has been previously described. o Corridor Ten -Devil Canaan to Intertie via North Shore, Sus1tna River, an Denali Highway Corridor Ten connects Devil Canyon-Watana with the Intertie in the vicinity of Cantwell by means of Corridor Segments CJAG. Segment CJA is part of Corridor Three and, as such, has been previously described. Segment AG has also been described above as part of Corridor Eight. As noted earlier, the Corridor Ten terrain consists of mountainous stretches with accompanying gently rolling to moderately rolling hills and flat plains covered in places with tall-growing vegetation. o Corridor Eleven -Devil Canyon to the Intertie via Tsusena Creek/Chulitna River Another northern route connecting Devil Canyon with Watana is that created by connecting Corridor Segment CJA (part of Corridor Three) with Segment AHI of Corridor Six. n-Watana to the Intertie Another route under consideration is Corridor JA-CJHI. From north to south, this involves a corridor extending from the Intertie near Summit Lake, heading 2-89 J • I I I easterly along the Middl e Fork Chulitn a drainage into Caribou Pass. From here, it parallels t he Jack Rive r and connects with the Portage Creek-Devil Creek route, Segment HJ. At po int J , located in the Devil Creek drainage east of High Lake, the corridor splits, with one segment extend i ng westerly to Dev il Canyon and the other extending east to the Watana Dam site along previously described Corridor Segments JC and JA, respectively. Terrain features of this r oute have been previously described. o Corridor Thirteen -Watana to Devil Canthn via South Shore, Devil Canyon to Intert1e v1a N5r Shore, Susitna River Corridor Segments AB, BC, and CF are comb i ned to f orm this cor ri dor. Descri ptions of the terrain crossed by these segments appear in discussions of Corridor One (ABCD) and Corridor Three (AJCF). o Corridor Fourteen -Watana to Devil Canthn via North shore, Dev1t canyon to lntert1e via sou Sho r 1, Sus itna River This corridor would connect the damsites in the directionally opposite order of the previous corridor, and include Corridor Segment AJCD. Again, as parts of Corridors One and Three, the terrain features of this corridor have been previously described. o Corridor Fifteen -Watana to Devil Canthn via Stephan Laket Devil Canyon to lntertie v1a Nort Shore, Susi na River Corridor Two (ABEC) and Corridor Three (CF) form to create this study-Jrea corridor. Terrain features have been presented under th~ discussions of each of these two corridors. -Northern Study Area In the· northern study area, four transmission 1 ine . corridor options exist for connecting Healy and Fairbanks (Figure 8.49). o Corridor One -Healy to Fairbanks via Parks Highway Corridor One (ABC), consisting of Segments AB and BC, starts in the v ~ci nity of the Healy Power Plant. From here, the corridor heads northwest, crossing the 2-90 J J J j J J ex i st i ng Golde n Va ll ey El ect r i c Assoc i at i on Transmiss i on Lin e, the ra i lroad, and the Parks Hi ghway before turn i ng to the nort h and parallel i ng this road t o a point due west of Browne. Here, as a resu l t of t erra i n featur es, the corridor turns northeast, cross i ng the Parks Highway once again as well as the existing transm i ss i on line, the Nenana River, and t he r ailroad, and cont i nues northeasterly to a poi nt northeast of the Clear Missile Early Warning Station (MEWS). Cont in uing northward, the corridor eventually crosses the Tanana River east of Nenana, then heads nor t heast, first cro s sing Little Goldstream Creek, then the Parks Hi ghway just north of the Bonanza Cr eek Experimental Forest. Before reach i ng the drainage of Oh i o Creek~ this corridor turns back to the northeast, crossing the old Parks Highway and heading into the Ester Substation west of Fairbanks. Terrain along th i s entire corr i dor segment is relatively flat, wi th the exception of the foothills north of the Tanana River. Much of the route, especially that port i on between the Nenana and the Tanana River crossings, is very broad and flat, has stand i ng water during the summer months and, in some places, i s overgrown by dense stands of tall-growing vegetation. This corridor segment crosses the foothills northeast of Nenana, also a heavily wooded area. An opt i on to the above (and n0t shown in t he figures), that of closely paralleling and sharing rights-of-way with the existing Healy-Fa i rbanks transmiss i on line, has been considered. While it is usual l y attractive to parallel existing corridors wherever possible, th i s option necessitates a great number of road crossings and an extended length of the corridor paralleling the Parks Highway. A potent i ally s i gnificant amount of highway-abutting land would be usurped f or containment of t he right-of-way. These features, in combination, eliminated this corridor from furthe r evaluation. o Corr i dor Two -Healy to Fairbanks via Crossing Wood River The second corridor (ABDC) is a variation of r~rr i dor One and consists of Segments AB and BDC. At 90int B, ea s t of the Clear MEWS, instead of turn i ng north, the corridor continues to the northeast . ~•ossing Fish 2-91 j j j J J J J j Creek, the Totatlan i ka River, Tat l ani ka Creek, the Wood Ri ver, and Crooked Creek before turning to the north. At a p0 i nt equidistant from Crooked and Will ow Creeks, the corri dor turns north, crosses the Tanana Ri ver east of Hadley Slough, and extends to the Ester Subst at i on. North of the Tanana River, this cor ri dor segment also crosses Rose Creek and the Parks Highway. Where it diverges from the original corridor, this corridor traverses extensive areas of flat ground, wi th standing water very prevalent throughout the summer months. Heavily wooded areas occur in the broad floodplain of the Tanana River, in the vicinity of the river crossing, and in the foothills around Rose Creek. o Corridor Three -Healy to Fairbanks via Healy Creek and Japan Hills Cor~i dor Three (AEDC), consisting of Segments AE and EDC, exits the Healy Power Plant in an easterly direction . i nstead of proceeding northwest ; this corridor, following its interconnection with the Intertie Project, heads east up Healy Creek, passing the Usibelli Coal Mine. Near the headwaters of Healy Creek, the corridor cuts to the east, crossing a high pass of approximately 4,700 feet elevation and descending into the Cody Creek drainage. From Healy to the Cody Creek drainage, the terrain is relatively gentle but bounded by very rugged mountain peaks. The elevation gain from the Healy Power Pl ant to the pass between the Healy Creek-Cody Creek drainages is approximately 3,300 feet. From here, the segment turns to the northeast, following the lowlands accompanying the Wood River. The corridor next parallels the Wood River from the An~erson Mountain area, past Mystic Mountain, and out into the broad floodplain of the Tanana River east of Japan Hills. Near ~he confluence of Fish Creek and the Wood River, the corridor turns north and intersects the north-south portion of Cor ridor Two (Segment DC), after first passing through Wood River Buttes. Much of the area north of J apan Hi l ls is flat and very wet with stands of dense, t al l -growing vegetation. 2-92 I I I I I I I I I I (c) o Corridor Fou r -Healy to Fairbanks via Wood River and Fort Wa 1 nwn ght Corridor Four (AEF) is a derivation of Corridor Three and is composed of Segments AE and EF. PointE i s located just north of Japan Hills along the Wood River. From here, the corridor deviates from Co rri dor Three by running north across the Blair Lake Air Force Range, Fort Wainwright, and several tributaries of the Tanana River, before reaching the crossing of Salchaket Slough. Corridor Four passes Clear Creek Butte on the east. A new substation would be located on the Fairbanks side of the Tanana River just north of Goose Island. From Point E to Point F, the terrain of the corridor is flat and very wet, and again, dense stands of tall-growing vegetation exist both in the better drained portions of the flat lands and in the v:cinity of the river crossing. Corr i dor Screening The objectives of the screening process were to focus on the previously se lected corridors and select those best meeting technical, economic, and environmental criteria. (i) Reliability Reliability is an uncomprom1s1ng factor in screening al ternative transmission line corridors. Many of the criteria utilized for economic , environmental, and technical reasons also relate to the select i on of a corridor within which a line can be operated with minimum power interruption . Six bas i c factor s were considered in relation to reliability: -Elevation: Lines located at eleva t ions below 4,000 fe et will be less exposed to severe wi nd and i ce conditions, wh i ch can interrupt St!rvice . -Aircraft: Avoidance of areas near aircraft landing and takeoff operat i ons will minimize risks from collisions. -Stability: -Existing Power Lines: Avoidance of areas susceptible to land, ice, and snow slides will red uce chance of power failures. Avo i dance of crossing existing transmission lines will reduce the possibility of lines touching dur i ng fa ilures and will facilitate repairs. 2-93 1 J J J -Topography: Lines located in areas with gent l e relief will be easier to construct and repair. -Access: Lines located in reasonable proximity to transportation corr i dors will be more quickly accessible and, t :1erefore, more quickly repaired if any fai l ures occur . (ii) Technical Screening Criteria Four primary and two secondary technical factors wer e considered in the scree~ing of alternative corridors. Primary As·pects: o Topography o Climate and Elevation low temperatures, snow depth, icing, and severe winds are very important parameters in transmission design, operation, and reliability. Climatic factors become more severe in the mountains, where extreme winds are expected for exposed areas and passes. Alaska Power Administration believes that elevations above 4,000 feet in the Alaska Range and Talkeetna Mountains are completely unsuitable for lotJting major transmission facilitjes. Significant advantages of reliability and cost are expected if the lines are routed below 3,000 feet in elevation. This elevation figure was used in the screening process. o Soils Although transmission lines ar less affected by soils and foundation limitations than railroads ard pipelines, it is more reliable to build a transmission 1ine on soil that does not appear to be underlain by sei:;mically induced ground failures or on a swainpy area where maintenance and inspection may create prob 1 ems. These factors were ut n i zed in the screening process. Because of the vast areas of wetlands in the study area, particularly in the southern portion, it was not possible to locate a corridor that would avoid all wetland areas. 2-94 ,1· ., I 1 'I j . J j J J j o hength of Corridors -Secondary Aspects: ___ .._,~- o Vegetation and Clearing Heavily forested areas must be cleared prior to construction of the transmission line. Clearing the vegetation will. cause some disruption of the soi 1. If not properly stabilized through restoration and vegetation, increased erosion will result. If the vegetation is cleared up to river banks on stream crossings, it may result in additional sedimentation. During the corridor screening, those corridors crossing through large expanses of heavily timbered areas were eliminated. o Other Highway and river crossings were avoided as much as possible. (iii) Economic Screening Criteria Three primary and one secondary aspect of the economic criteria were considered. -Primary Aspect~: o Length o Right-of-Way Whenever possible, existing rights-of-ways were shared or paraleled to avoid the problems associated with pioneering a corridor in previously inaccessible areas. o Access Roads -Secondary Aspects: In addition to the major considerations concerning economic screening of corridors, some other aspects were also considered. These include topography, since it is more economical to build a line on a flat corridor than on a rugged or a mountainous one; and limiting the number of stream, river, highway, road, and railroad crossings in order to minimize costs. 2-95 l J .J i j (iv) Environmental Screening Criteria Because of the potential, adverse environmental impacts from transmission line construction and operation, environmental criteria were carefully scrutinized in the screening process. Past experience has shown the primary environmental considerations to be: -Aesthetic and Visual (including impacts to recreation) -Land Use (including ownership and presence of existing rights~of-way) Also of significance in the evaluation process are: -Length -Topography -Soils Cultural Resources -Vegetation Fishery Resources -Wildlife Resources A description and rationale for use of these criteria are presented below: -Primary Aspects: o Aesthetic and Visual The presence of large transmission line sb·uctures in undeveloped areas has the potential for adverse aesthetic impacts. Furthermore, the presence of these lines can conflict with recreational use, particularly those nonconsumptive recreational activities such as hiking and bird watching where great emphasis is placed on scenic values. The number of road crossings encountered by transmission line corridors is al3o a factor that needs to be inventoried because of the 2-96 1 j ... .J potential for visual impacts. The number of roads crossed, the manner in which they are crossed, the nature of existing vegetation at the crossing site (i.e., potential visual screening), and the number and type of motorists using the highway all influence the desirability of one corridor versus another. Therefore, when screening the previously selected corridors, consideration was focused on the presence of recreational areas, hiking trails, heavily utilized lakes, vistas, and highways where views of transmission line facilities would be undesirable. o Land Use The three primary components of land use considerations are: 1) land status/ownership, 2) existing rights-of-way, and 3) existing and proposed development . . Land/Status/Ownership The ownership of land to be crossed by a transmission line is important because cer~ain types of ownership present more restrictions thar others. For example, some recreation areas such as st_~ · and federal parks and areas like game refuges ~~c military lands, among others, present poss.~:~· constraints to corridor routing. Private landowners generally do not want transmission lines on their lands. This information, when known in advance, permits corridor routing to avoid such restrictive areas and to occur in areas where land use conflicts can be minimized • . Existing Rights-of-Way Paralleling existing rights-of-way tends to result in less environmental impact than that which is associated with a new right-of-way because the creation of a new right-of-way may provide a means of access to areas normally accessible only on foot. This can be a critical factor if it opens sensitive, ecological areas to all ter~ain vehicles. 2-97 .. j l j J J J J J J j J . . j j Imp&ct on soils, vegetation, stream crossings, and others of the inventory categories can also be lessened through the paralleling of existing access roads and cleared rights-of-way. Some impact is still felt, however, even. though a right-of-way may exist in the area. For example, cultural resources may not have been identified in the original routing effort. Wetlands present under existing transmission 1 ines may 1 ike\'1ise be negatively influenced if ground access to the vicinity of the tower locations is required. There are common occasions where paralleling an existing facility is not desirable. This is particularly true in the case of highways that offer the potential for visual impacts and in situations where paralleling a poorly sited transmission facility would only compound an existing problem . . Existing and Proposed Developments This inventory identifies such things as agricultural use; planned urban developments, such as the proposed capital site; existing residential and cabin developments; the location of airports and of lakes used for float planes; and similar types of information. Such information is essential for locating transmission line corridors appropriately, as it presents conflicts with these land use activities. Secondary Aspects: o Length The length of a transmission line is an environmental factor and, as such, was considered in the screening process. A longer line \'Jill require more construction activity than a shorter line, will disturb more land area, and will have a greater inherent probability of encountering environmental constraints. o Topography The natural features of the terrain are significant from the standpoint that they offer both positive and negative aspects to transmission line routing. Steep 2-98 • .. .. I I slopes, for example, present both difficult construction and soil stabilization problems with potentially long-term, negative environmental consequences. Also, ridge crossings have the potential for visual impacts. At the same time, slopes and elevation changes present opportunities for routing transmission lines so as to screen them from both travel routes and existing communities. When planning corridors then, the identification of changes in relief is an important factor. o Soils Soils are important from several standpoints. First of all, scarification of the land often occurs during the construction of transmission lines. As a result, vegetation regeneration is affected, as are the related features of soil stability and erosion potential. In addition, the development and installation of access roads, where necessary, are very dependent upon soil types. Tower designs and locations are dictated by the types of soils encountered in any particular corridor segment. Consequently, the review of existing soils information is very significant. This inventory was conducted by means of a Soil Associations Table, Table 8.41. Table 8.42 presents the related definitions as they apply to the terms used in Table 8.41. o Cultural Resources The avoidance of known or potential sites of cultural resources is an important component of the routing of transmission 1 ines. In pl annirag for Susitna Project transmission lines, however, information on the presence of cultural resources is, for the most part, unavailable. An appropriate program for identifying and mitigating impacts of the finally selected route ... is necessary. o Vegetation The consideration of the presence and location rf various plant communities is essential in transmission line siting~ The inventory of plant communities, such as those of a tall-growing nature or wetlands, is significant from the standpoint of construction, clearing, and access road development requirements. In addition, identification of locations of endangered 2-99 ,. .. -.---~-,-~ . ----~----:.._·-. :· ,--~-~ _____ !:_~ ~~·--~:;-~-=:~_-~: .. :.:.-.~:,-.=--=-=-=--=--~~:-=-=--=---:-: .. -: .: ::< ... ·:--.----~~~,.--~------........... :~ .. ~.:::::::::_'I . ~ ·. ·. . . ' . : _·---·-. -. -.---<-. -.. . . . . . . -. -.. ·. ·~, --' ---_, "~~~-·~-·~~ .::-.... -., ',_:·..._ ____ ._.~ ... :::•:.J~~--~""--~ and threatened plant species is also critical. While several Alaskan plant species are currently under review by the U.S. Fish and Wildlife Service, no plant species are presently 1 i sted under the Endangered Species Act of 1973 as occurring in Alaska. No corridor currently under consideration has been identified as traversing any location known to support these identified plant species. o Fishery Resources The presence or absence of resident or anadromous fish in a stream is a significant factor in evaluating suitable transmission line corridors. The corridor•s effects on a stream's resources must be viewed from the standpoint of possible disturbance to fish species, potential loss of habitat, and possible destruction of spawning beds. In addition, certain species of fish are more sensitive than others to disturbance. Closely related to this consideration is the number of stream crossings. The nature of the soils and vegetation in the vicinity of the streams and the manner in which the streams are to be crossed are also important environmental considerations when routing transmission lines. Potential stream degradation, impact on fish habitat through disturb~nce, and long-term negative consequences resulting from siltation of spawn1hg beds are all concerns that need evaluation in corridor routing. Therefore, the number of 3tream crossings and the presence of fish species and habitat value were considered when data were av ai 1 ab 1 e. o Wildlife Resources -- The three major groups of wildlife which must be considered in transmission corridor screening are big g~me, birds, and furbearers. Of all the wildlife species to be considered in the course of routing studies for transmiss·ion lines, big game species (together with endangered species) are most significant. Many of the big game species, including grizzly bear, caribou, and sheep, are particularly sensitive to human intt'usion into relatively undisturbed areas. Calving grounds, denning areas, and other important or unique habitat areas as identified by the Alaska Department of Fish and Game 2-100 • .. • .. were identified and incorporated into the screening process .. Many species of birds such as raptors and swans are sensitive to human disturbance. Identifying the presence and location of nesting raptors and swans permits avoidance of traditional nesting areas. Moreover, if this category is investigated, the presence of endangered species (viz, peregrine falcons) can be determined. Important habitat for furbearers exists along many potential transmission lin~ corridors in the railbelt area, and its ioss or disruption would have a direct effect on these animal populations. Investigating habitat preferences, noting existing habitat, and identifying populations through available information are important steps in addressing the selection of environmentally acceptable alternatives. (v) Screening Methodology -Technical and Economical Screening Methodology The parameters required for the technical and economical analyses were extracted from the environmental inventory tables (Tables B.38 through B.40). The tables, together with the topographic maps, aerial photos, and existing published materials, were used to compare the alternative corridors from a technical and economical point of view. The parameters used in the analysis were: length of corridors, approximate number of highway/road crossings, approximate number of river/creek crossings, land ownership, topography, soils, and existing rights-of-way. The main factors contributing to the economical and technical analyses are combined and listed in Tables B.43, B.44, and B.45. It should be noted that-most of the parameters are in miles of line length, except the tower construction. In this analysis, it was decided to assign 4.5 towers for each mile of 345-kV line. In order to screen the most qualified corridor, it was decided to rate the corridors as follows: Corridor rated A -recommended Corridor rated C -acceptable but not preferred Corridor rated F -unacceptable 2-101 ( I I • I • I • .. From the technical point of view, reli~ility, is the main objective. An environmentally and economically sound transmission llne was rejected if the line was not reliable. Thus, any line which received an F technical rating, was assigned an overall rating of F and eliminated from further consideration. The ratings appear in each of the economical and technical screening tables (Tables B.43, B.44, ~d B.45) and are summarized in Table 8.46. -Environmental Screen'!_ng Methodology In order to compare the a 1 tern at i ve corridors (Figures 8.47, B.48, and B.49) from an environmental st~dpoint, the environmental criteria discussed above were combined into environmental constraint tables {Tables B.47, B.48, and B.49). These tables combine information for each corridor se~ent into the proper corridors under study. This permitted the assignment of an environmental rating, which identifies the relative rating of each corridor within each of the three study areas. The assignment of environmental ratings is a subjective, qualitative technique intended as an aid to corridor screening. Those corridors that are recommended are identified with and "A," while those corridors that are acceptable but not preferred are identified with a "C." Finally, those corridors that are considered unacceptable are identified with an "F." (d) Selected Corridor The selected corridor consists of the following segements: Corridot ADFC (Figures B.50 and B.51) Corridor ABCD (Figures B.52 and B.53) Corrid1r ABC (Figures B.54 through 8.57) -Southern Study Area: -Central Study Area: -Northern Study Area: Specifics of these corridors and re~ons for rejection of others are discussed below. More d~ail on the screening process and the specific tech;,ical ratings of each alternative are in Chapter 10 of Exhibit E. ( i) ~uthern Study Area In the southern study area, Corridor Segment AEF and, hence, Corridor Three (AEFC) were determined unacceptable. This results prim~ily from the routing of the segment through the rel ati vel y we 11-deve loped and heavilY utili zed Nancy Lake state recreation area. Adjustments to this z ... 1o2 (; .. route to make it more acceptable were attempted but no alterations proved successful. Consequently, it was recommended this corridor be dropped from further consideration. Corridor One (ABC') was identified as acceptable but not preferred, thus given the C rating. Its great length, its traversing of residential and other developed lands, and the numerous creek crossings and extensive forest clearing involved relegate this corridor to this environmental rating. Economically and technically, this corridor has more difficulties than the other two considered. This is a longer l1ne and crosses areas which may require easements in the area north of Anchorage. · Corridor Two {AOFC) was .identified as the candidate which would satisfy most of the screening criteria. This corridor is shown in Figures B.50 and B.51, and stretches from an area north of Willow Creek to Point MacKenzie in the south. The corridor is located east of the lower Susitna River and crosses the Little Susitna River. The corridor also crosses an existing 138 kV line owned and operated by Chugach Electric Association (CEA), which starts at Point MacKenzie and extends to Teeland Substation. Up to this point in the corridor selection study, Point MacKenzie has been considered a terminal point for Susitna power. It was assumed that an underwater cable crossing would be provided at this location~ Upon further study and data-gathering it has become known that the existing crossing at Point MacKenzie has experienced power interruptions caused by ship's anchors snagging the submarine cables. CEA, which owns the submarine cables, required additional transmission capacity to Anchorage. After thoroughly studying the matter, it has opted for a combined submarine/overhead cable transmission across Knik Arm and onto Anchorage. This was the most desirable option to CEA, both from the environmental and technical point of vi e'IJ. The CEA crossing will be located approximately eight miles northeast of Point MacKenzie on the west shore of the Knik Arm and across from Elmendorf Air Force Base in the vicinity of Six Mile Creek. This crossing is located northeast of the Anchorage Harbor, away from the heavy ship traffic, thereby reducing risk of anchor damage to the cab 1 e. 2-103 .. • • 1 I .. I (; i ) It is intended to terminate Corridor ADFC at this new crossing point and extend the transmission corridor to Elemendorf Air Force Base and beyon.d to Anchorage. Although the crossing is approximately eight miles northeast of Point MacKenzie, it does not influence the results of this corridor selection and screening process . The best corridor has been selected and screened. During routing studies minor deviations outside the corr·idor will have to occur in order to terminate at the revised crossing point. However, preliminary investigations indicate it will be possible to select a technically, economically, and environmentally acceptable route, particularly since an existing transmission line can likely be paralleled from the selected corridor to the revised crossing point. Further~ore, CEA has received the necessary permits and is constructing an underwater crossing at Knik Arm, indicating acceptable levels of environmental impact. Central Study Area In the central study &rea, several corridor segments and, hence, their associated corridors were determinEd to be unacceptable. The first of these, Corridor Segment BEC, appears as part of Corridors Two (ABECD), Five (ABECJHI), Seven {CEJAHI), Nine (CEBAG), and Fifteen (ABECF). The reason for rejecting this segment is primarily that th2 developed recreation ·area around Stephan Lake would be needlessly harmed, because viable options exist to avoid intruding into this area. Again, modifying this route to something more acceptable failed. Consequently, it is recommended that these five corridors be dropped from further· consideration. Corridor Segment AG was also determined not to warrant further consideration because of its approximate 65-mile length, two-thirds of which would possibly require a pioneer access road. Also, extensive areas of clearing would be required, opening the corridor to view in some scenic locations. Finally~ the impacts on fish and wildlife habitats are potentially severe. These preliminary findings, coupled with the fact that more viable options to Segment AG exist, suggest that consideration of this corridor segment and} therefore, Corridors Eight (CBAG) and Ten (CJAG) shou1d be terminated. Corridors Eleven (CJAHI) and Twelve (JA-CJHI) were identified as acceptable. This rating arose from the fact that, as shown in Environmental Constraint Table B.48, 2-104 • I numerous constraints affect this routing. Information from recently completed field investigations suggest that these constraints cannot be overcome and the routes should be rejected. Furthermore, the technical and economical ratings preclude these corridors from further consideration. Corridor Segment HJ has been moved so that it no longer parallels the Oevi1 Creek drainage; the new location HC is selected to avoid both High Lake and the Devil Creek drainage. It then follows the Portage Creek drainage to the point of intersection with Corridor Segment JH, near the creek's headwaters. Subsequent investigations have confirmed that this corridor segment is not viable and, consequently, Corridors Four and Five are eliminated from further consideration. Corridors Six intrudes on valuable wildlife habitat and would cross numerous creeks, none of which are currently crossed by existing access roads. I~ addition, a high mountain pass and its associated shallow soils, steep slopes, and surficial bedrock constrain this routing. Finally, its crossing of areas over 4,000 feet in elevation makes it technically unacceptable, so this corridor is dropped from further consideration. Corridors Three (AJCF) and Fourteen (AJCD) have been identified as acceptable but not recommended because of the CJ Corridor Segment. This corridor segment intrudes upon an existing recreation area at High Lake and contravenes existing views of the Alaska Range; it also crosses valuable habitat for sensitive big game species. Corridor One (ABCO), as shown in Figure B.48, was one of the three recommended corridors. Constraints to this routing do exist, however, and will need to be further evaluated before modifications to this corridor are suggested. This corridor is one of the shortest~in length (38 miles) of all corridors considered in this area. It is recommended, therefore, because of its technical and economical rating. Corridor Thirteen (ABCF) is also an acceptable but not preferred corridor. With the presence of the developed recreation area at Otter Lake, Corridor Thirteen could require special attention in Segment CF. The technical rating for this corridor is attractive because of the short length of transmission line and the fact that the lines could be constructed within a reasonable distance to the access roads. Because of crossings of deep ravines and 2-105 .. .. - - - - - - - - (iii) forest clearing, this corridor is not recommended economic a 11 y. Fiaures B.52 and B.53 show the location of the recommended corridor in the area from Watana to an area in the vicinity of Gold Creek, and it essentially straddles the Upper Susitna River. The area of the corridor between Watana and Devil Canyon may be extended to the north and is dependent on the route the access road may take. Every effort will be made to coordinate the transmission lines with the access road~ Northern Study Area Corridors Three (AEDC) and Four (AEF) were determined unacceptable because of many constraints, and thus, rated F~ They include: the lack of an existing access road; problems in dealing with tower erection in shallow bedrock zones; the need for extensive wetland crossings and forest clearing; the 75 river or creek crossings involved; and the fact that prime habitat for waterfowl, peregrine falcons, caribou, bighorn sheep, golden eagle, and brown bear would be crossed. In addition, Corridor Four crosses areas of si~nificant land use constraints and elevations of over 4,000 feet. Corridor Two (ABDC) was identified as acceptable but not preferred, and thus, rated C. Certain constraints identified for this corridor suggest that an alternative is preferable. Compared with Corridor One, Corridor Two crosses additional wetlands and requires the development of more access roads and the clearing of additional forest 1 ands. Corridor One (ABC), shown in Figures B.54 to B.57, was the only recommended corridor in the northern study area. While many constraints were identified under the various categories, it appears possible to select a route within this corridor to minimize constraint influences. This corridor is attractive economically, because it is close to access roads and the Parks Highway. The visual impact can be lessened by strategic placement of the line. This line also best meets technical and economical requirements. (e) Route Selection (i) Methodology After identification of the preferred transmission line corridors, the next step in the route selection process i nvo 1 ved the analysis of the data as gather·ed and presented 2-106 .. on the base map. Overlays were compiled so that various constraints affecting construction or maintenance of a transmission facility could be viewed on a single map. The map was used to select possible routes within each of the three selected corridors. By placing all major constraints (e.g., areas of high visual exposure, private lands, endangered species, etc.) on one map, a route of least impact was selected. Existing facilities, such as transmission lines and tractor trails within the study area, were also considered during the selection of a minimum impact route. Whenever possible, the routes were selected near existing or proposed access roads, sharing ( i i) whenever possible existing rights-of-way. The data base used in this analysis was obtained from the following sources: -An up-to-date land status study; -Existing aerial photos; -New aerial photos conducted for selected sections of the previously recommended transmission line corridors; -Environmental studies including aesthetic considerations; -Climatological studies; -Geotechnical exploration; -Additional field studies; and -Public opinions. Selection Criteria The purpose of this section is to identify three selected routes; one from Healy to Fairbanks, the second f;om the Watana and Devil Canyon damsites to the intertie, and the third from Willow to Anchorage. The previously chosen corridors were subject to a process of refinement and evaluation based on the same·technical, economic, and environmental criteria used in corridor selection. In addition, special emphasis was concentr~ed on the following points: -Satisfying the regulatory and permit requirements; -Selection of routing th~ provides for minimum visibility from highways and homes; and -Avoidance of developed agricultural lands and dwellings. (iii) Environmental Analysis The corridors selected were analysed to arrive at the route which is the most compatible with the environment and also 2-107 • . .. meet the engineering and economic objectives. The environmental analysis was conducted by the process described below: Literature Review Data from various literature sources, agency communications, and site visits were reviewed to inventory existing environmental variables. From Juch an inventory, it was possible to identify environmental constraints in the recorrmended corridor locations. Data sources were cataloged and filed for later retrieval. -Avoidance Routing ~y Constraint Analysis To establish the most appropriate location for a transmission line route, it was necessary to identify those environmental constraints that coulu be impediments to the development of such a route. Many specific constraints were identified during the preliminary screening; others were determined during the 1981 field investigations. By utilizing information on topography, existing and proposed land use, aesthetics, ecological features~ and cultura·l resources as they exist within the corridors, and by careful placement of the route with these considerations in mind, impact on these various constraints was minimized. Base Maps and Overlays Constraint analysis information was placed on base maps. Constraints were identified and presented on overlays to the base maps. This mapping process involved using both existing information and that acquired through Susitna Project studies. This information was first categorized as to its potential for constraining the development of a transmission line route within the preferred corridor and then placed on maps of the corridors. Environmental constraints were identified and recorded directly onto the base maps. Overlays to the base maps were prepared indicating the type and extent of the encountered constraints. Three overlays were prepared for each map: one for visual constraints, one for man-made, and one for biological constraints. These maps are presented as a separate ~ocument (12). 2-108 • I 6 (iv) Technical and Economic Analysis Route location objectives are to obtain an optimum combination of reliability and cost with the fewest environmental problems. In many cases, these objectives are mutually camp at i b 1 e. Throughout the evaluation, much emphasis was placed on locating the route relatively close to existing surface transportation faci l'it i es whenever pass i b 1 e. The factors that contributed heavily in the technical and economic analysis were: topography, climate and elevation, soils, length, and access roads. Other factors of less importance were vegetation, and river and h~ghway crossings. These factors are detailed in Tables B.37 and B.50. -Selection of Alternative Routes The next step in the route selection process involved the analysis of the data presented on the base maps. The data were used to select possible routes within each corridor. By placing all major constraints on one map, routes of smallest impacts were selected. Existing facilities, such as transmission lines and tractor trails within the study area~ were also taken into consideration during the selection of a least impact route. -Evaluation of a Primary Route The evaluation and selection of alternative ~outes to arrive at a primary route involved a closer examination of each of the possible routes using mapping process and data previously descl"ibed. Preliminary routes were compared to determine the route of least impact within the primary corridors of each study area. For ex amp 1 e, such variables as number of stream and road crossi~gs required were noted. Then, following the field studies and through a comparison of routing data$ including the route•s total length and its use of existing facilities, one route was designated the primary route. Land use, land ownership, and visual impacts were key factors in the selection process. (v) Route Soil Conditions Description Baseline geological and geotechnical information has been compiled through photointerpretation and terrain 2-109 1 l unit mapping. The general objective was to document the conditions that would significantly affect the design and construction of the transmission 1 ine towers. t•1ore specifically, the conditions included the forms o' various origins, noting the occurrence and distriltution of significatn geologic factors such as permafrost, potentially unstable slopes~ potentially eordible soils, possible active fault traces, potential construction materi.als, active floodplains, organic materials, etc. Work on the airphoto interpretation consisted of several activities culminating in a set of terrain unit maps showing surface materials, geologic features and conditions in the project area. The first activity consisted of a revit~w of the literature concerning the geology of the intertie corridors and transfer of the information gained to high-level photographs at a scale of 1:63,000. Interpretation of the high-level photos created a regional terrain framework which assisted in interpretation of the low-level 1:30,000 project photos. Major terrain divisions identified on the high-level photos were then used as an aerial guide for delineation of more detailed ter-rain·units on the low-level photos .. The primary effort of the work was the interpretation of over 140 photos covering about 300 square miles of varied terrain. The land area covered in the mapping exercise is shown on map sheets and displayed in detail on photo mosaics (13). As part of the terrain analysisr the various bedrock units and dominant lithologies were identified using published U.S. Geological Survey reports. The extent of these units was approximately shown on the photographs, and using exposure patterns, shade, texture, and other features of the rock unit as they appeared on the photographs, unit boundaries were drawn. Physical characteristics and typical engineering properties of each terrain unit were considered and a chart for each corridor was developed. The charts ·identify the terrain units as they have been mapped and characterize their properties in numerous categories. This allows an assessment of each unit•s influence on various project features. 2-110 .. .. . -Terrain Unit Analysi~ The terrain unit is a special purpose term comprising the land forms expected to occur from the ground surface to a depth of about 25 feet. The terrain unit maps for the proposed Anchorage to Fairbanks transmission line show the aerial extent of the specific terrain units which were identifed during the air photo investigation and were corroborated in part by a limited onsite surface investigation. The units document the general geology and geotechnical characteristics of the area. The north and south corridors are separated by several hundred miles and not surprisingly encounter different geomorphic provinces and climatic conditions. Hence, while there are many land forms (or individual terrain units) that are colllitOt11 to both corridors, there are also some landforms mapped in just one corridor. Tlie landforms or individual terrain units mapped in both corridors were breifly described. Several of the landforms have not been mapped independently but rather as compound or complex terrain units. Compound terrain units result when one landform overlies a second recognized unit at a sha 11 ow depth (less than 25 feet), such as a thin deposit of glacial till overlying bedrock or a mantle of lacustrine sediments overlying till. Compl~x terrain units have been mapped where the surficial exposure pattern of two landforms are so intricately related that they must be mapped as a terrain unit complex, such as some areas of bedrock and colluvium. The compound and complex terrain units were described as a composite of individual 1 andforms comprising them. The stratigraphy, topographic position, and aerial extent of all units, as they appear in each corridor, were summarized on the terrain unit properties and enginee"ing interpretations chart (13). (vi) Results and Conclusions A study of existing information and aerial overflights, together with additional aerial coverage, was used to locate the recommended route in each of the southern, central, and northern study areas. Additional environmental information and 1 and status studies made it possible to align the routes to avoid any restraints. 2-111 - Terrain unit maps describing the general material expected in the area were prepared specifically for transmission line studies and were used to locate the routes away from unfavorable soil conditins whenever possible. The selected transmission line route for the three areas of study is presented in Exhibit G. As a first step, the 3 to 5 mile wide corridor previously selected for each of the three study areas was narrowed to a half mile-wide corridor based on the previous criteria. This centerline represents a right-of-way width of 500 feet. The width is adequate for three, single-circuit, parallel lines with tower structures having horizontal phase spacing of 33 feet. However, between the Devil Canyon damsite and Gold Creek, the width of the right-of-way is 650 feet which is needed to accommodate four single-circuit linese Enviromental constraint analysis information was placed on base maps and overlays (12). Subsequent to the submission of the Feasibility Study (4) a further refinement process on the line route has taken place to reflect the possibility of land acquisition problems at locations along the corridor. This process has resulted in an improved routing, generally close to the earlier proposal, in the Fairbanks to Healy and the Willow to Anchorage line sections. Also since the Feasibility Study the proposals for access to the power development have undergone reassessment. This has resulted in a decision to provide access to Watana from the Denali Highway and not build the Watana to Devil Canyon link until the latter site is developed. Because of this lack of early access to Devil Canyon the main Switching Station for the transmission has been relocated at Gold Creek. The earlier line routing proposals were accordingly reviewed to establish the optimum location for lines for Watana to Gold Creek and from Devil Canyon to Gold Creek. This route was established within the corridors examined in detail earlier, using the same methodology as before. (f) Towers, Foundations and conductors The Anchorage and Fairbanks Intertie will consist of existing lines and a new section between Willow and Healy. The new section .. 2-112 • • • f will be built to 345 kV standards but will be temporarily operated at 138 kV and will be fully compatible with Susitna requirements. (i) Transmission Line Towers Section of Tower Type Because of the unique soil conditions in Alaska which are characterized by extensive regions of muskeg and permafrost, conventional self-supporting or rigid towers will not provide a satisfactory solution for the proposed transmission Jine. Permafrost and seasonal changes in the soil are known to cause 1 arge earth movemerts at some locations, requiring towers with a high degree of flexibility and capability to sustain appreciable loss of structural integrity. A guyed tower is well suited to these conditions; these include the guyed~V, guyed-Y, guyed delta, and guyed portal type structures. The type of structure selected for the construction of the Intertie is the hinged-guyed steel X-tower, a refinement of the guyed structure concept; this type of tower is, therefore, a prime candidate for use on the Watana transmission system. Guyed pole-type structures will be used on larger angle and dead end structures; a similar arrangement will be used in specially heavy loading zones. The design feature of the X-tower include hinged connections between the legs and the foundation and four longitudinal guys attached in pairs to two guy anchors, providing a high degree of flexibility with excellent structural strength. The wide leg spacing results in relatively low foundation forces which are carried on pile type footings in soil and steel grillage or rock anchor footings where rock is close to the surface. In narrow·right-of-way situations, cantilevt~r steel pole structures are anticipated with foundations consisting of cast-in-place concrete augered piles. In the final design process, experience gained in the construction and operation of the Intertie will be used· in the final selection of the structue type to be used for the Watana transmission. 2-113 • .. "' .. A 11 tower structures wi 11 be constructed of 11 weatheri ng 11 type steel which matures to a dark brown color over a period of a few years and is considered to have a more aesthetically pleasing appearance than either galvanized steel or aluminum. Climatic Studies and Loadings Climatic studies for transmission ·lines were performed to determine probable maximum wind and ice loads based on historical data. A more detailed study incorporating additional climatic data was carried out for the Intertie final design. These studies have resulted in the selection of preliminary loading for the line design. Details of the climatic studies for Watana transmission lines may be found in Reference 14. Preliminary loadings selected for line design should be confirmed by a detailed study, similar to that performed for the Intertie, that will examine conditions for the Healy to Fairbanks, Willow to Anchorage and Gold Creek to Watana sections of the route together with an update of the Healy to Willow study incorporating any data from field measurement stations collected in the interim period. Based on data currently av ai 1 able, it appears that the line can be divided up into zones as far as climatic loading is concerned as follows: -Normal Loading Zone -Heavv Ice Loadinq Zone ~ ... -Heavy Wind Loading Zone The heavy ice and heavy wind zones will have an additional critical loading case including to reflect the special nature of the. zone. -Tower F ami"l y A family of tower designs will be developed as follows: • Suspension towers will be provided for both standard span plus angle (up to 3°) application and for lonn span or light angla (0° to 8°) application . • Tension towers will be provided for light angle and dead end (0° to 8°), for large angle and dead end (8° to 50°) and for minimum angle and dead end (50° to 90°). 2-114 • .. • ! p ! The maximum wind span and weight span ratios to be utilized will be set in final design to reflect the rugged nature of the terrain along the 1 ine route. Some trial spotting of towers in representative tertains will be used to ~uide this selection. Minimum weight span to wind span ratio limits will be set during tower spotting and a "low temperature template" used to check that unexpected uplift will not develop at low weight span towers for very low temperatures. The span to be used in design wi 11 be the subject of an economic optimization study. A span of not less than 1,200 ft is expected with spans in the field varying to greater and lesser values in specific cases depending upon span and loading zone .. (ii) Tower Foundations -Geotechnical Conditions The generalized terrain analysis {13) was conducted to collect geologic and geotechnical data for the transmission l·tne corridm~s, a relatively large area. The engineer"ing characteristics of the terrain units have been generalized and described qualitatively .. When evaluating the suitability of a terrain unit for a specific use, the actual properties of that unit must be verified by onsite subsurface investigation, sampling, and 1 aboratory testing. The three main types of foundation materials along the transmission line are: • Good material, which is defined as overburden which permits augered excavation and allows installation of concrete without special form work; • Wetland and permafrost mater·i a1 which requires special design detai ·1 s; and .• Rock material defined as material in which drilled-in anchors and concrete footings can be used. Based on (lerial, topographic, and terrain unit maps, the following was noted: • For the southern study area: Wet 1 and and permafrost materials constitue the major part of this area. Some rock and good foundation materials are present in this area in a very sma11 proportion. 2-115 • For the central study area: Rock foundation and good materials were observed in most of this study areao • For the nm"'thern study area: The major part of this area is wetland and permafrost materials. Some parts have rock ma.teri al s. -Types of Foundation The types of tangent tower envisaged for these lines will require foundations to suppot the leg or mast capable of carrying a predominantly vertical load with some 1 ateral shear, and a guy anchor foundation. The cantilever pole structure foundation is required to resist the high overturning moment inherent in the cant i 1 ever arrangement .. The greater part of the combined maximum reactions on a transmission tower footing is usually from short duration loads such as broken wire, wind, and ice. With the exception of heavy-angle, dead-end or terminal structures, only a pa.rt of the total reaction is of a permanent nature. As a consequence, the permissible soil pressure, as used in the design of building foundations, may be considerably increased for footing for transmission structures. The permissible values of soil pressure used in the footing design will depend on the structur:2 and the supporting soil. The basic criterion is that displacement of the footing is not restr·i cted because of the flexibility of the selected x-frame tower and its hinged connection to the footing. The shape and configuration of the selected tower are important factors in foundation considerations. Loads on the tower consist of vertical and horizontal loads and are transmitted down to the foundation and then distributed to the soi 1 • In a tower p 1 aced at an angle or used as dead-end in the line, the horizontal loads are responsible for a large portion of the loads on the foundation. In addition to the horizontal shear, a moment is also present at the top of the foundation, creating vertical download and uplift forces on the footing. 2-116 .. .. rr -... .: To enable the selection of a safe and economical tower foundation design for each tower site it is necessry to select a footing which takes account of the actual soil conditions at the site. This is done by matching the soil conditions to a series of ranges in soil types and groundwater conditions which have been predetermined during the design phase to cover the full range of soils expected to be encountered along the line length. ?reconstruction drilling, soil sampling, and laboratory testing at representative locations along the line enable the design of a family of footings to be prepared for each tower type from which a selection of the appropriate footing for the specific site can be made during construction. The fondation types for structure legs and masts will be g;""outed anchor where rock is very shallow or at surface and steel grillage with granu1ar backfill where soil is competent and not unduely frost sensitive. In areas where soi 1 s are weak and whey·e permafrost or part i c u 1 ar 1 y forst -heave prone mater i al is encountered driven steel piles will be used. Guy anchors wi 11 use grouted anchors in rock. Grouted earth or helical plate screw-in anchors with driven piles wi11 be used in permafrost or very weak soils. Proof 1 oad testing of pi 1 es and dr i 11 ed in anchors wi 11 be required both for design and to check on the as-built capacity of these foundation elements during construction. (iii) Voltage Level and Conductor Size Economic studies were carried out of transmission utilizing 500 kV, 345 kV, and 230 kV ac. At each voltage level an optimum conductor capacity was developed. Schemes involving use of 500 kV or ~45 kV on the route to Anchorage and 345 kV or 230 kV to Fairbanks were investiqated. The study recommended the adoption of two 345 kV uiiits to Fairbanks and three 345 kV unit$ to Anchorage. Comparative studies were carried out of the possible use of HVDC which indicated no economic advantage of such a scheme. 2-117 • .. u u The 345 kV system studies ind·;,,ated that a conductor capacity of 1950 MCM per phase was economical with due account for the value of losses. A phase bundle consisting of twin 754 MCM Rail (45/7) ACSR was proposed as meeting the required capacity and also having acceptable corona and radio interference performance. Detailed design studies as part of the final design will compare the economics of ths conductor configuration with the use of alternatives such as twin 954 MCM Cardinal (54/7) ACSR and single 215.6 MCM Bluebird (84/19) ACSR which could give comparable electrical performance with better structural performance. Cardinal because of a 15 percent superior strength-to-weight ratio can be sagged tighter than Rail, to result in savings in tower height and/or increased spans. Bluebird because of a smalier circumference and projected area compared with a twin conductor bundle attracts some 15 percent less load from ice or wind; together with its greater strength this leads to less sag under heavyloadings and 1 ighter loads for the structures to carry. conductor swing angles will also be reduced thus reducing tower head size requirements and edge of right-of- way clearing .. 2.8 -Selection of Project Operati~ ) A reservoir simulation model was used to evaluate the optimum method of operating the Susitna hydroelectric project for a range of past project flows at the Gold Creek gaging station 25 miles downstream of the Devil Canyon damsite. The process that led to the selection of the flow scenario used in this license application includes the following steps: -Determination of pre-project flows at Gold Creek, Watana and Devil Canyon for 32 year~ of record; Selection of range of flows to be included in the analysis; -Selection of timing of flow releases to match fishery requirements; -Selection of maximum drawdown at Watana; Determination of energy produced for the seven flow release scenarios being studied; -Determination of net benefits for each flow scenario; -Selection of range of flows acceptable based on ecomomic factors; and -Influence of instream flow and fishery considerations on selectjon of project operational flows. 2-118 • j ( I I • I • I • ... A summar·y discussion of the detailed analysis is presented in the following paragraphs. (a) Pre-Project Flows The USGS has operated a gaging station (Station 15292000) at Gold Creek on the Susitna River continuously since 1950. They have also operated the Cantwell gage near Vee Canyon on the upper end of the proposed Watana Reservoir since 1961. These two gaging stations combined with a regional analysis were used to develop a 32 year record for the Cantwell gage. The flow at \~atana and Devil Canyon was then calculated using the Cantwell flow as the base and adding an incremental flow proportional to the additional drainage area between the Cantwell gage. and the damsites. The resulting flows at Watana and Devi 1 Canyon are presented in Tables 8.51 and B.52. (b) Range of Post-Projec~ Flows Dur·ing investigation of the full range of flows appropriate for use as operational target flows at Gold Creek, two factors were considered: that operational flow which would produce the maximum amount of usable energy from the project neglecting all other considerations (Case A), and that operational summer flow which would have minimum impact on downstream fishery and instream flow uses (Case D). Between these two end points five additional flow scenarios were established. The minimum target flows for all seven flow scenarios are presented in Table 8.53. (c) Timing of Flow Releases In the reach of the river between Talkeetna and Devil Canyon it is presently perceived that the most important aspect of successful salmon spawning is providing access to the side channel and slough areas connected to the main stem spawning areas. Access to these areas is primarily a function of water level (fiow) in the main channel of the river during the period when the salmon must gain access to the spawning arease Field studies during 1981 and 1982 have indicated the access should be provided in late July, August and early September. Thus, the project operational flow has been scheduled to satisfy this requirement; i.e., the flow will be increased the last week of July, held constant during August and the first two weeks of September and then decreased to a level specified by energy demands in mid to late September. (d) Maximum Ofawdown In Reference 4 the maximum drawdown was selected as 140 feet for Watana and 50 feet for Oevi 1 Canyon. Because the Devil Canyon maximum drcwdown would be controlled by technical considerations the 50 foot drawdown was not reconsidered and has been retained as 2-119 • (e) (f) . . . . -. . . . . . . ··-.' -·~~ ... p .. ·" -...!' ~' the upper limit for Devil Canyon. On the other hand, the Watana maximum drawdown is governed by intake structure cost, energy product-ion, and downstream flow considerations; thus, it was refined during the 1982 studies. This refinement process resulted in the selection of 120 feet as the maximum drawdown for the Watana development. Energy Production Using the pre-project flows, the seven flow release scenarios, and the maximum drawdowns established in subsections (a)-(d) above were input to the reservoir simulation model. The amount of energy produced, the flow at Gold Creek and the reservoir levels were determined for the 32 years of record. A summary of the energy produced using the seven flow scenarios is presented in Table B.54. Net Benefits To determine the net economic value of the energy produced by the Susitna Hydroelectric Project the mathematical model commonly known as OGP 5 (Optimized Generation Planning Model, Version 5) was used to determine the present worth value (1982 dollars) of the long-term (1993 to 2051) production costs (LTPWC) of supplying the Railbelt energy needs by various alternative means of generation. A more detailed description of the OGP model is contained in the Section 1.5. The analysis was performed for the 11 best thermal option 11 as well as for the seven flow scenarios for operating Susitna. The results are presented in Table 8.55. The net benefit presented in Table B.55 is the difference between the L TP~~C for the "best therma 1 option" and the L TPWC for the various Susitna options~ In Table B.55, Case A represents the maximum usable energy option and results in a net benefit of $1215 million. As flow i~ transferred from the winter to the August-September t iflle pet"i od for fishery and i nstrearr flow mitigation purposes the amount of usable energy decreases. This decrease is not significant until the flow provided at Gold Creek during August reaches the 12,000 to 14,000 cfs range. For a flow of 19,000 cfs at Gold Creek, a flow scenario that represents minimum downstream fishery impact, approximately 45 percent of the potential project net benefits have been foregone. (g) Operational Flow Scenario Selection Based on the economic analysis discussed above, it was judged that, while case A flows produced the maximum net benefit, the loss in net benefits (compared to Case A) for cases A1, Az, and C were of an acceptable magnitude. The loss associated with Case c1 is on the borderline between acceptab 1 e and 2-120 (h) unaccepab·l e. As fishery and i nstream fl 0\'1 impact (and hence mitigation costs associated with the various flow scenarios) are quantified the decrease in mitigation costs associated with high flows may warrant selecting a higher flow case such as C1. However, the loss in net benefits associated with Cases C2 and D was not acceptable and it is doubtful ·that the mitigation cost reduction associated with these higher flows will bring them into the accepab 1 e range. Instream Flow and Fishery Impact on Flow Selection =- As noted ear1ier, the primary function controlled by the late summer flow is the abi 1 ity of the salmon to gain access :o their traditional spawn·ing grounds. Instream flow assessment conducted during 1981 (the wettest July-August on record) and 1982 (one of the driest July-Augusts on record) has indicated that, for flows of the Case A magnitude, severe impacts would occur which can not be mitigated except by compensation through hatchery construction. For flows in the 10,000 to 12,000 cfs range (flows similar to those that occured in Aug!.lst., 1982) the salmon can, with difficulty, obtain access to their spawning grounds. To insure that the salmon can always obtain access to spawning ar·eas during a flow of 10,000 to 12,000 cfs simple, relatively low cost physical mitigation measures are incorporated into the mitigation plan presented in Chapter 3 of Exhibit E. Based on this assessment the Case A and A1 fl 0\'1 scenarios are considered uracceptable, thus establishing a lower limit for the acceptable flow range as approximately 10,000 cfs (Case A2) at Gold Creek during August. As a result, by combining the economic analysis and the instream flow considerations the Case C scenario providing a flow of 12,000 cfs at Gold Creel< during August (see Table 8.53) has been selected as the project operational flow~ As a more refined assessment of fishery impact, mitigation costs and projected project n~t benefits becomes available, the project operational flow will be adjusted. However~ it is unlikely that the final flow selection will be less than 10,000 cfs or greater than 16,000 cfs during August at Go 1 d Creel<. 2-121 "' ' 3 -DESCRIPTION OF PROJECT OPERAT~DN 3 -DESCRIPTION OF PROJECT OPERATION 3.1 -Operation Within Railbelt Power System A staged development is planned for implementation of Susitna power generation. The following schedule for unit start-up is proposed: Start-up Date 1994 (Jan.) 1994 (July) 2002 Dam Site Wo.tana Watana Devil Canyon *Installed generating capacity. No . and S i ze of Units (~1W) Brought On-line 4 X 170 2 X 170 4 X 150 Total Susitna On-line Capacity* ({~W) 680 1020 1620 As shown above, the first four units are scheduled to be on line at Watana in early 1994, followed by the remaining two Watana units in mid 1994. Startup .of all four units at Devil Canyon is planned for 2002. , Of the total project installed capacity of 1620 ~1W, 1280 MW were utilized as the basis for generation planning. The ramaining 340 MW are planned to meet the needs for spinning reserve capacity. This section describes the operation of the Watana and Devil Canyon power plants in the Railbelt electrical system. Under currP-nt condi- tions in the Railbelt, a total of nine utilities share responsibility for generation and distribution of electric power, with limited inter- connections. The proposed arrangements for optimization and control of the dispatch of SusitnJ power to Railbelt load centers is based on the expectation that a single entity will eventually be set up for this purpose. In the year 2010 the projected Railbelt system, with Susitna on line, is projected to comprise: Coal-fired Steam: Natural Gas GT: Diesel: Natural Gas CC: Hydropower: TOTAL 13 MW 326 MW 6 MW 317 MW 1775 MW 2437 MW It is important to note that the Susitna project will be the single rr:ost significant power source in the system. The dispatch and distri- 3-1 .. bution of power from all sources by the most economical and reliable means is therefore essential. The general principles of reliability of plant and system operation, reservoir regulation, stationary and spin- ning reserve requirements, and maintenance programming are discussed in this section. Estimates of dependable capacity and annual energy pro- duction for both Watana and Devi 1 Canyon are presented. Operating a,nd maintenance procedures are described, and the proposed performance monitoring system for the two projects is also outlined. 3.2 -f._lant and System Operation Requirements The main function of system planning and operation control is the allo- cation of generating plant on a short-term operational basis so that the total system demand .is met by the available generation at minimum cost consistent with the security of supply. The objectives are gener- ally the same for long-term planning or short-term operational load dispatching, but with important differences in the latter case. In the short-term case, the actual state of the system dictates system relia- bility requirements, overriding economic considerations in load dis- patching. An important factor arising from economic ano reliability considerations in system planning and operation is the provision of stationary reserve and spinning reserve capacity. Figure B.58 shows the daily variation in demand for the Railbelt system during typical winter and summer weekdays and the seasonal variation in monthly peak demands for estimated loads in a typical year (the year 2000). 3.3 -General Power Plant and System Railbelt rriteria The following basic reliability standards and criteria have been adopted for planning the Susitna project. (a) Installed Generating Capacity Sufficient generating capacity is installed in the system to in- sure that the probability Jf occurrence of load exceeding the available generating capa~ity shall not be greater than one day in ten years (Loss-of-load probability (LOLP) of 0.1). (b) Transmission System Capabilitr The high-voltage transm1ssion system should be operable at all load levels to meet the following unscheduled single or double contingencies without instability, cascading or interruption of lead. -The single contingency situation is the loss of any single gen- erating unit, transmission line, transformer, or bus (in addi- tion to normal scheduled or maintenance outages) without ~xceed­ ing the applicable emergency rating of any facility; and 3-2 • • ·~ ·l -The double contingency situation is the subsequent outage of any remaining equipment, line or subsystem without exceeding the short time emergency rating of any facility. In the single contingency situation, the power system must be cap- able of readjustment so that all equipment would be loaded within normal ratings, and in the double contingency situation, within emergency ratings for the probable duration of the outage. During any contingency: -Sufficient reactive power (MVAR) capacity with adequate controls is installed to maintain acceptable transmission voltage pro- fi 1 es. -The stability of the power system is maintained without loss of load or generation during and after a three-phase fault, cleared in normal time, at the most critical location. (c) Summary Opet"'ational reliability criteria thus fall into four main cate- gories: -LOLP of 0.1, or one day in ten years, is maintained for the recommended plan of operation; -The single and double contingency requirements are maintained for any of the more probable outages in the plant or transmis- sion system; -System stability and voltage regulation are assured from the electrical system studies. Detailed studies for load frequency control have not been performed, but it is expected that the stipulated criteria will be met with the more than adequate spinning reserve capacity with six units at Watana and four units at Devil Canyon; and -The loss of all Susitna transmission lines on a single right- of-way has a low level of probability. In the event of the loss of all 1 i nes, the hydro plants at Watana and Devil Canyon are best suited to restore power supply quickly after the first line is restored since they are designed for 11 black start" operation. In this respect, hydro plans are superior to thermal plants because of their inherent black start capability for restoration of supply to a large system. 3.4 -Economic Dispatch of Units A Susitna Area Control Center wi 11 be located at Watana to control both the Watana and the Devil Canyon power plants. The control center will be linked through the supervisory system to the Central Dispatch Control Center at Willow. 3-3 .. .. I f ., .. -·---·----..:.._,_. --"•u~,:_----·-'---~" :....-~-'" -S'.:J:.v_· --- Ope rat ion wi 11 be semi -automatic with gene rat ion instruct ions input from the Central Dispatch Center at Willow, but with direct control of the Susitna system at the control center at Watana. The supervisory control of the entire Alaska Railbelt system vlill be done at the Central Dispatch Center at Willow. A high level of control automation with the aid of digital computers will be sought, but not a complete computerized direct digital control of the Watana and Devil Canyon power plants. Independent operator controlled local-manual and local-auto operations will still be possible at Watana and Devil Canyon power plants for testing/corrmissioning or during emergencies. The control system will be designed to perform the following functions at both power plants: -Start/stop and loading of units by operator; -Load-frequency control of units; -Reservoir/water flow control; -Continuous monitoring and data logging; -Alarm annunciation; and -~Jan-machine communication through visual display units (VDU) and con- sole. In addition, the computer system will be capable of retrieval of tech- nical data, design criteria, equipment characteristics and operating 1 imitations, schematic diagrams, and operating/maintenance records of the units. The Susitna Area Control Center will be capable of completely indepen- dent control of the Central Dispatch Center in case of system emer- gencies. Similarly it will be possible to operate the Susitna units in an emergency situation from the Central Dispatch Center, although this should be an unlikely operation considering the size, complexity, and impact of the Sus i tna generating plants on the system. The Central Dispatch Control Engineer decides which generating units should be operated at any given time. Decisions are made on the basis of known information, including an 11 order-of-merit 11 schedule, short- term demand forecasts, limits of operation of units, and unit mainten- ance schedules. (a) Merit-Order Schedule In order to decide which generating unit should run to meet the system demand in the most economic manner, the Control Engineer is provided with information of the running cost of each unit in the form of an 11 order-of-merit11 schedule. The schedule gives the cap- acity and fuel costs for thermal units, and reservoir regulation limits for hydro plants. (b) Optimum Load Dispatching One of the most important functions of the Control Center is the accurate forecasting of the load demands in the various areas of the system. 3-4 • .. .. (c) Based on the anticipated demand, basic power transfers between areas, and an allowance for reserve, the planned generating capa- city to be used is determined by taking into consideration the reservoir regulation plans of the hydro plants. The type and size of the units should also be taken into consideration for effective load dispatching. In a hydro-dominated power system such as the Rail belt system woul'1 be if Susitna is developed, the hydro unit will take up a much greater part of base load operation than in a thermal domin- ated power system. The planned hydro units at Watana typically are well suited to load following and frequency regulation of the system and providing spinning reserve. Greater· flexibility of operation was a significant factor in the selection of siA units of 170 MW capacity at Watana, rather than fewer ·1 arger-si ze units. O~~!ting Limits of Units There are strict constraints on the minimum load and the loading rates of machines: to dispatch load to these machines requires a systemwide dispatch program taking these constraints into consid- eration. In general, hydro units have excellent startup and load following characteristics; thermal units have good part-loading characteristics. Typical plant loading limitations are given below: ( i) Hydro Units -Reservoir regulation constraints resulting in not-to- exceed maximum and minimum reservoir levels, daily or seasonally. Part loading of units is impossible in the zone of rough turbine operation (typically from above no-load-speed to 50 percemt load) due to vi brat ions arising from hydraulic surges. (ii) Steam Units -Loading rates are slow (10 percent per minute). -The units may not be able to meet a sudden steep rate of rise of 1 oad demand. The units have a minimum economic shutdown period (about 3 hours). -The total cost of using conventional units includes bank- ing, raising pressure and part-load operations prior to maximum economic ope rat ion. 3-5 • • (d) (iii) Gas Turbines -Cannot be used as spinning reserve because nf very poor efficiency and reduced service life. -Require 8 to 10 minutes for normal start-up from cold. Emergency start up times are of the order of 5 to 7 minutes. Optimum Maintenance Program An important part of operational planning \'klich can have a signif- icant effect on operating costs is maintenance programming. The program specifies the times in the year and the sequence in \'Klich plant is released for maintenance. 3.5 -Unit Operation Reliability Criteria During the operational load dispatching conditions of the power system, the reliability criteria often override economic considerations in scheduling of various units in the system. Also im~ortant in consider- ing operational reliability are system response, load-frequency con- tra 1, and spinning reserve capab i 1 it i es. (a) Power System Analyses Load-frequency response studies determine the dynamic stability of the system due to the sudden forced outage of the 1 argest unit (or generation block) in the system. The generation and load are not balanced, and if the pick-up rate of new generation is not ade- quate, loss of load will eventually result from under-voltage and under-frequency relay operation, or load-shedding. The aim of a well designed high security system is to avoid load-shedding by maintaining frequency and voltage within the specified statutory limits. (b) System Response and Load-Frequency Control To meet the frequency requirements, it is necessary that the effective capacity of generating plant supplying tr1e system at any given instant should be in excess of the load demand. In the absence of detailed studies, an empirical factor of 1.67 times the capacity of the largest unit in the system is normally taken as a design criterion to maintain system frequency within acceptable limits in the event of the instantaneous loss of the largest unit. It is recommended that a factor of 1. 5 times the largest unit size be considered as a minimum for the Alaska Railbelt system, with 2 times the largest unit size as a fairly conservative value (i.e., 300 to 340 MW). 3-6 • (c) The quickest response in system generation will come from the hydro units. The large hydro units at Watana and Devil Canyon on spinning ri~serve can respond in the turb i ni ng mode within 30 seconds. !his is one of the particularly important advantages of the Susitna hydro units. Gas turbines can only respond in a second stage operation within 5 to 10 minutes and vmuld not strictly qualify as spinning reserve. If thermal units are run part-loaded (eog., 75 percent), this wou1d be another source of spinning reserve. Ideally, it would be ddvantageous to prov·ide spinning reserve in the thermal generation as well, in order to spread spinning reserves evenly in the system, with a compromise to economic loading resulting fran such an operation. Pro;ective Relaying System and Devices The primary protective relaying systems provided for the gener- ators and transmission system of the Susitna project are designed to disconnect the faulty equipment from the system in the fastest possible time. Independent protective systems are installed to the extent necessary to provide a fas t-c 1 eari ng backup for the primary protective system so as to limit equipment damage, to limit the shock to the system and to speed restoration of service. The relaying systems are designed so as not to restrict the normal or necessary network transfer capabilities of the power system. 3.6 -Disp~tch Control Centers The operation of the Watana and Devil Canyon power plant in relation to the Central Dispatch Center can be considered to be the second tier of a three-tier control structure as follows: -Central Dispatch Control Center (345 kV network) at \aJillow: manages the main system energy transfers, advises system configuration and checks overpll security. -Area Control Centet· (Generation connected to 345 kV system; for ex- ample, Watana and Devil Canyon): deals with the 1oading of genera- tors connected directly to the 345 kV network, switching and safety precautions of local systems, checks security of interconnections to main system. -District or Load Centers (138 kV and lower voltage networks): gener- ation and distribution at lower voltage levels. For the Anchorage and Fairbanks areas, the district center functions are incorporated in the respective area control centers. Each generating unit at Watana and Devil Canyon is started up, loaded and operated~ and shut down from the Area Control Center at Watana according to the 1 oad i ng demands from the Centra 1 Dispatch Contra 1 Center with due consideration to: 3-7 • .. . --Watana reservoir regulation criter·ia; De vi 1 Canyon reservoir" regulation criteria; -Turbine loading and de-loading rates; -Part loading and maximum loading Gharacteristics of turbines and generators; -Hydraulic transient characteristics of waterways and turbines; -Load-frequency control of demands of the system; and -Voltage regulation requirements of the system. The Watana Area Control Center is equipped with a computer-aided con- trol system to efficiently carry out these functions. The computer- aided control system allows a minimum of highly trained and skilled operators to perform the control and supervision of Watana and Devil Canyon plants from a single control room. The data information and retrieval system will enable the performance and alarm monitoring of each unit individually as wel1 as the plant/reservoir and project oper- ation as a whole. 3.7 ~ Susitna Project Operation ""' Substantial seasonal as well as over-the-year regulation of the river flow is achieved with the two reservoirs. The simulation of the reser- voirs and the power facilities at the two developments was carried out on a monthly basis to assess the energy potential of the schemes, river flows downstream and flood control possibilities with the reservoirs. The following paragraphs summarize the main features of reservoir oper- ation. An optimum reservoir operation v11as e5tablished by an iterative process to minimize net system operating costs while maximizing firm and usable energy production. Seven alternative operating cases for the Watana reservoir (A, A1, Az~ C, c1~ Cz, and D) were selected for study to defi n<= the pass i b 1 e range of operation. Case A rept·esents an optimum power and energy scenario, while Case D reflects a case of 11 mi nimum impact on downstream fisheries 11 • The other five cases are inter,mediate levels of power operation and dolfmstream impact. These essentially define monthly minimum flows at Gold Creek that must be maintained while providing energy consistent with other project constraints. For feasibility report purposes, operation model ".1.\ 11 was adopted for project design. Studies with appropriate fisheries mitig~ion measures were developed based on Case A flows at ~ld Creek. Table 8.54 presents a summary of potential energy generation with three of the seven different operating rules for Watana and Devil Canyon deve 1 opments. • Average annual energy potential of Watana development is 3460 GWh, and that of Devil Canyon development is 3450 GWh. A frequency analysis of the river hydrology was made to derive the firm annual energy potential (or the dependable capacity) of the hydro development. The Federal Energy Regulatory Commission (FERC) defines the dependable c~acity of hydroelectric plants ai: "the capacity which, under the most adverse flow conditions of record can be relied upon to carry system load, provide dependable reserve capacity, and meet firm power obligations taking into account seasonal variations and othar charac- teristics of the load to be supplied". Based on the Railbelt system studies and previous experience on large hydroelectric projects, it was assumed that a dry hydrological sequence with a recurrence period of the order of 1:50 years waul d canst itute an adequate re 1 i ability for the Railbelt electrical system. An analysis of annual energy patenti al of the reservoirs showed Uat the lowest annual energy generation, 5380 GWh, has a recurrence frequency 1 in 300 years. The second lowest annual energy of 5400 GWh has a recurrence frequency of 1 in 70 years. This latter figure has been adopted as the firm energy from the development. The monthlY distribution of firm annual ~ergy from the reservoir simulation has been used in system generation planning studies. Average monthlY energy based on the recorded sequence hydrology is used in the economic analysis. 3-9 • .. '' 4 -ENERGY PRODUCTION AND SUPPORTING DATA 4 -DEPENDABLE CAPACITY AND ENERGY PRODUCTION Table B.26 summarizes design parameters for dependable capacity and energy production levels. 4.1 -Hydrology (a) Historical Streamflow Records Historical streamflow data are available for several gaging sta- tions on the Susitna River and its main tributaries. Continuous gaging records were available for the following eight stations on the river and its tributaries: Maclaren River near Paxson~ Denali, Cantwell, Gold Creek and Susitna stations on the Susitna River, Chulitna Station on the Chulitna River, Talkeetna on the Talkeetna River, and Skwentna on the Skwentna River. The longest period of record available is for the station at Gold Creek (32 years from 1949 to 1981). At other stations, record length varies from 6 to 23 yearso Gaging was continued at all these stations as part of the project study program. A gaging station was estab- lished at the Watana damsite in 1980, and streamflow records are available for the study period. Partial streamflow records are available at several other stations on the river for varying periods; the station locations are shown in Figure 8.59. It should be noted that gaging will continue as the project pro- gresses in order to improve the streamflow record, as wel1 as after project completion at selected sites required for project operation. (b) Water Resources Above its confluence with the Chulitna River,, the Susitna contri- butes approximately 20 percent of the mean annual flow measured at Susitna Station near Cook Inlet. Figure 8.60 shows how the mean annual flow of the Susitna increases towards the mouth of the river at Cook Inlet. Seasonal variation of flow in the river is extreme and ranges fr-om very low values in winter (October to April) to high summer values (May to September). For the Susitna River at Gold Creek, the average winter and summer· flows are 2210 and 20,200 cfs respec- tively, i.e., a 1 to 10 ratio. This large seasonal differ·ence is mainly due to effects of glacial and snow melt in the surrmer. The monthly average flows in the Susitna River at Gold Creek are given in Figure 8.61.. Some 40 percent of the streamflow at Gold Creek originates above the Denali and Maclaren gages. This catch- ment generally comprises the glaciers and associated high moun- tains. On the average, approximately 87 percent of the streamflow recorded at Gold Creek station occurs during the summer months., At higher elevations in the basin the distribution of flows is concentrated even more in the summer months. For the Mac1aren River near Paxson ( Elevation 4520), the average winter and summer 4-1 (c) . ' ' . . . . ' .' . . . ~ . . . . . '· . '. flows are 144 and 2,100 cfs respectively, i.e. a 1 to 15 ratio. The monthly percent of annual discharge and mean monthlY dis- charges for the Susitna River and tributaries at the gaging sta- tions above the Chulitna confluence are given in Table 6.56. Streamflow Extension Synthesized flows at the Wat an a and Dev i 1 Canyon dams it es are pre- sented in Tatll es B .51 and B ,52. Flow duration curves based on these monthly estimates are presented for Watana and Devil Canyon damsites in Figures 8.62 and 8.63. The inhouse FILLlN computer program developed by the Texas Water Deve 1 o pment Board was used to fi 11 in gaps in historic a 1 stream- flow records at the eight continuous gaging stations. The 32 year record (up to 1981) at Go 1 d Creek was used as the base record . The procedure ~opted for filling in the d~a gaps uses a multi- site regression technique which analyzes monthlY time-series data. Flow sequences for the 32-year period were generated at the remaining seven stations. Using these flows at Cantwell station and observed Go 1 d Creek flows , 3 2-year month 1 y flow sequences at the Watana and Devil Canyon damsites were generated on the basis of prorated drainage areas. Recorded streamflows at Watana and oev i 1 Can yon were i nc1 uded in the historic a 1 record where a v ai 1- able. Critical Streamflow Used for Dependable CapacitY ._,,.... --- AV et age annu a 1 energy potent i a 1 of Wat an a dev e 1 oprr.ent is 3460 GWh , and that of Devil Canyon developmem; is 3450 GWh. A frequency aralysis of the river hydrology was made to derive the firm annual energy potential (or the dependable capacity) of the hydro development. The analysis of annual energy potential of the reservoirs showed that the lowest annual energy generation has a recurrence frequency approximately equal to 1 in 50 years reulting in an annual energy of 5380 GWh (see Figure 8.64). This figure has been adopted as the finn energy from the development, Experience with other large hydroelt•r.tric projects ·indicates tlJat 1 in 50 years provides adequate rellability. (e) Floods The most common causes of flood peako. in the Susitna River Basin are snowmelt or a ccmbin;xtion of snowmelt and rainfall over a large area. An>1ual maximum peak disc!Hrgcs generally occur be- tween May :~nd October with the majority t appro xi mate 1 y 60 percent) occurring in June. Sorne of the annual maximum flood peaks have also occurr':!d in Augu~t or \eter and are the rl'su1t of heavy rains over large ;;reas iW\:•Pented by signif·icant $f1CI-.iil"llt from higher 'I \J .. >!,' '·¥ fJ elevations and glacial runoff. Table B.57 presents selected flood peaks re(orded at different gaging stations. Routing of fl oo dthro ugh the W at an a and Oev i 1 Canyon dams is presented in Figure 8.58. A reg·:onal flood peak and volume frequency analysis was carried out using the recorded floods in the Susitna River 1..1d its pr inc i p a 1 t ri but ar i es • These an a 1 ys es were conducted for two different time periods. The first period, after the ice breakup and before freezeup (May through October), contains the largest floods which must be accommodated by the project. The second period represents that portion of time during which ice conditions occur in the river (October through May). These floods, although smaller, car. be accompanied by ice jamming and must be considered during the construction phase of the project in planning the design of cofferdams for river diversion. A s~ of multiple line~ regression equations were developed using physiographic basin parameters such as catchment area, stream length, precipitation, snuwfall amounts, etc., to estimate flood peaks at ungaged sites in the basin. In conjunction with the .analysis of shapes and volumes of recorded large floods at Gold Creek, a set of project design flood hydrographs of different recurrence intervals were develo~ed (see Figures 8.65 and 8.66). The results of the a!Jov e an a 1 ys is were us ect for est im at i ng flood hydrographs at the damsites and ungaged streams and rivers along the access road alignments for design of spill>'~ctYS, culverts, etc. Table 8.58 lists mean annual, 50-, 100-, and 10,000-year floods at the Watana and Devil Canyon damsites and at the Gold Creek gage. The p.-oposed reservoirs at Watana and oevi 1 Canyon would be class- ified as "large" and with "high hazard potential" according to the guidelines for safety inspect ion of dams 1 aid out ':Jy the Corps of Engineers. This would indicate the need for the probable maximum flood (PMF) to be considered in the ev~·luation of the proposed projects. Estimated peak discharges during the PMF at se 1 ected locations are included ir Table B.58, and the PMF hydrograph is presented in Figure B.66. Table B.59 lists the maximum flows through the vurious dam facilities for the 50, 10,000, and PMF events. (f) f.}_ow Adjustments Evaporation from the proposed WatJ.na and Oev i1 Canyon reservoirs has been evaluated to determine its significance. Evaporation is influenced by air and water t~per~ures. wind. ~mospheric pres- sure, and dissolved solids within the water. However, thP evalua- tion of these factors' effects on evaporation is difficult because of their interdependence on each other. Consequently, more sim- plified methods were preferred and have be<;ln uti 1 i zed to estimate evaporation losses from the two reservoirs. 4-3 Tne monthlY evaporation estimates for the reservoirs are presented in Table 8.60. The estimates indicate that evaporation losses will be less than or equal to additions due to precipitation on the reservoir surface. Therefore, a conservative approach was taken, with evapm .. ation losses and precipitation gains neglected in the energy calculations. Leakage is not expected to result in significant flow losses. Seepage through the relict channel is estimated as less than one- half of one percent of the average flow and therefore has been neglected in the energy calculations to date. This approach will be reviewed when further investigations of the relict channel are completed. Minimunt flow releases are required throughout the year to maintain downstream river stages. The most significant factor in determin- ing the minimum flow value is '.he maintenance of downstream fish- eries. The monthlY flow requirements that were used in determina- tion of project energy potential are given in Table B.53. The numbers shown in Table B.53 represent the minimum stream flow required at Go 1 d Creek • These requ i r·ements wo u 1 d remain constant for all phas2s of project development. The actual flows released from the project at Watana (when Watana is op~rating alone) and at Devil Canyon (for combined operation of both dams) will be less than the required Gold Creek flows pror~ed on the basis of streamflow contributions from the intervening basin area. Tables B.61 and B.62 give the typical minimum required flow releases at Watana and Devil Canyon for a 32-year period of record. After completion of Devil Canyon, flow releases from Watana will be regu1 ated by system operation requirements. Because the tail- water of the Devil ~anyon reservoir will extend upstream to the Watana tailrace, there will be no release requirements for stream- flow maintenance of Watana for the Watana/Devil Canyon combined operating configuratior .. Existing water rights in the Susitna Basin were investigated to determine impacts on downstream flow requirements. Based on inventory information provided by the Alaska Department of Natural Resources, it was determined that existing water users will not be affected by the project. A 1 i sting of a 11 water appro pr·i at ions located within one mile of the Susitna River is provided in Table 6.63. 4.2 -Reservoir Data (a) ~eservoir Storage Gross s tor age vo 1 ume of the Wat an a reservoir at its norma 1 maxi mum operating level of 2185 feet is 9.5 million acre-feet, which is about 1.6 times the mean annual flow (MAF) at the damsite. Live 4-4 • .. i1 (b) storage in the reservoir is 3.7 million acre-feet. Devil Canyon reservoir has a gross storage of 1.1 million acre-feet and 1 i ve storage of 0.35 million ac~e-feet. The area-capacity curves for the Watana and Devil Canyon reser- voirs ~e provided in_Figure 8.67 and Figure 8.68, respectively. Rule Curves Operation of the reservoirs for energy production is based on tar- get water surface levels set for the end of each month. The tar- get level represents that level below which no energy beyond firm energy can be produced. In other words, if t~e reservoir level drops below the target onlY firm energy will be produced. In wetter years when the reservoir level surpasses the target level, energies greater than firm energy can be produced, but onlY as great as the s,ystem energy demand a 11 ows. With a reservoir rule curve which establishes minimum reservoir levels at different times during the year, it will be possible to produce more energy in wetter years during winter than by follow- ing a set energy pattern. At the same time, the rule curve ensures that low flow sequences do not materiallY reduce the energy potential below a set minimum or firm annual energy. The rule curves for Watana and Devil Canjon under combined opera- tion are shown in Figure 8.69. 4.3 -Operating Capabilities of Susitna Units .... . --- The operating conditions of both the Watana and Devil Canyon turbines are summarized in Table 8.64. (a) Watana The Watana powerhouse will have six generating units with a nomin- al capacity of 170 MW corresponding to the minimum December reser- voir level (Elevation 2114). The gross head on the plant wi 11 vary from 610 feet to approxi- matelY 735 feet. The maximum unit output will change with head, as shown on Figure 8.70. The rated head for the turbine has been established at 680 ~eet, which is the weighted average operating head on the station. Allowing for generator losses, the rated turbine output is 250,000 hp (185 .5 MW) at full gate. 4-5 • .. iy ···----·····--·--····-·-"'·-----~---~--~·----"-----~----·----'---'-.._;."-~'---__:._.~...;.---~--'-',:......;_c.--~-... '" The rated output of the turbines will be 250,000 hp at 680 feet rated net head. Maximum and minimum heads on the units will be 728 feet and 604 feet, respectively. The full gate output of the turbines will be about 275,000 hp at 728 feet net head and 209,000 hp at 604 feet net head. Jvergating of the turbines may be possible, providing approximately 5 percent additional power; however, at high heads the turbine output will be restricted to avoid overloading the generators. The best efficiency point of the t~rbines will be established at the time of preparation of bid docume~ts for the generating equipment and will be based on a detailed analysis of the anticipated operating range of the turbines. For preliminary design purposes, the best efficiency (best gate) output of the units has been assumed as 85 percent of the full gate turbine output. This percentage may vary from about 80 percent to 90 percent; in general, a lower percentage reduces turbine cost. The full gate and best gate efficiencies of the turbines will be about 91 percent and 94 percent respectively at rated head. The efficiency will be about 0.5 percent lower at maximum head and 1 percent lower at minimum head. The preliminary performance curve for the turbine is shown on Figure 8.71. The \aJatand plant output may vary from zero, with the units at standstill or at spinning reserve, to approximately 1200 when all six units are operating under maximum output at maximum head. A graph of plant efficiency versus output and the number of on-line units is shown in Figure 8.72. The load following requ·irements of the plant results in widely varying loading, but because of the multiple unit installation the total plant efficiency varies only slightly. (b) Devil Canyon The Devil Canyon powerhouse will have four generating units with a nominal capacity of 150 MW based on the minimum December reservoir level (Elevation 1405) and a corresponding gross head of 555 feet in the station. The gross head on the plant will vary from ti55 feet to 605 feet. The maximum unit output will change with head as shown in Figure 8.73. The rated average operating head for the turbine has been estab- lished at 575 feet. Allowing for generator losses, this results in a rated turbine output of 225,000 hp (168 MW) at full gate. 4-6 • "' .g The generator rating has been selected as 180 MVA with a 90 per- cent power factor. The generators will be capable of continuous operation at 115 percent rated power. Because of the high capa- city factor for the Devil Canyon station, the generators will therefore be sized on the basis of maximum turbine output at maxi- mum head, allowing for a possible 5 percent addition in power from the turbine. This maximum turbine output (250,000 hp) is within the continuous overload rating of the generator. Maximum and minimum heads on the units will be 542 feet and 600 feet, respectively. The full gate output of the turbines will be about 240,000 hp at maximum net head and 205,000 hp at minimum net head. Overgating of the turbines may be possible, providing approximately 5 percent additional power. For preliminary design purposes, the best efficiency {best gate) output of the units has been assumed at 85 percent of the full gate turbine output. The full gate and best gate efficiencies of the turbines will be about 91 percent and 94 percent, respectively, at rated head. The efficiency will be about 0.2 percent lower at maximum head and 0.5 percent lower at minimum head. The preliminary performance curve for the turbine is shown in Figure 8.74. The Devil Canyon plant output may vary from zero to 700 MW with all four units operating at maximum output. The combined plant efficiency varies with output and number of units opera.ting as shown in Figure 8.75. As with Watana~ the plant efficiency varies only slightly witn loading due to the load following capabilities of multiple units. 4.1 -Tailwater Rating Curve The tailwater rating curve for the Watana development is shown on Figure 8.67 and for the Devil Canyon development on Figure 8.68. 4-7 • • f 5 -STATEMENT OF POWER NEEDS AND UTILIZATION • .. ~.-<~;. -~ .... ,~-·-. 5 -STATEMENT OF POWER NEEDS AND UTILIZATION 5.1 -Railbelt Load Forecasts In this section of the Exhibit 7 the electrical demand forecasts for the Railbelt region are described. Historical and projected trends are identified and discussed, and the forecasts used in Susitna generation planning studies are presented. The feasibility of a major hydroelectric project depends in part upon the extent the available capacity and energy are consistent with the needs of the market to be served by the time the project comes on line. The Alaska Power Authority and the State of Alaska authorized load forecasts for the Alaska Railbelt region to be prepared independently of the Susitna feasibility study. The Railbelt region~ shown in Figure B.76, contains three electrical loa.d centers: the Anchorage-Cook Inlet area, the Fairbanks-Tanana Valley area, and the Glennallen-Valdez area. These areas are repre- sented by the shaded areas in the figure. Because of the relatively small electrical requirements of the Glennallen-Valdez load center (approximately 2 percent of the demand of the Anchorage-Cook Inlet area} it is not specifically analyzed as an ·individual load center. For this study the Glennallen-Valdez load center is considered to be part of the Anchor age-Cook In 1 et 1 o ad center. The e 1 ectri c a 1 demands for the Glennallen-Valdez area are determined as part of these projections and are combined with the Anchorage-Cook Inlet loads. Actually, these loads will not be served for the fores1aeable future by capacity from the intertied Railbelt area. (a) Scope of Studies There have bee0 two sets of forecasts developed and used during the feasibility study. In 1980, the Institute for Social and Economic Research (ISER) prepared economic and accompanying end- use energy demand projections for the Railbelt. The end-use forecasts were further refined as part of the fe~Jibility study to estimate capacity demands and demand patterns. Also estimated was the potential impact on these forecasts of additional load management and energy conservation efforts. These forecasts were used in several portions of th~ feasibility study, including the development selection study, and initial economic, finantial and sensitivity analyses. These forecasts are discussed in more detail in Subsection (b) below. In December 1981, Battelle Pacific Nm"-ci.~.--test Laboratories produced a series of revised load forecasts for the Railbelt. These fore- casts were developed as a part of the Railbelt Alternatives Study 5-1 • .. completed by Battelle under contract to the State of Alaska. Battelle•s forecasts were a result of further updating of economic projections by ISER and some revised end-use models developed by Battelle, which took into account price sensitivity and several other factors not included in tne 1980 projections. The Dec~mber 1981 Battelle forecasts were used in the final project staging, economic, financial and sensitivity analyses. The December 1981 Sattelle forecasts are presented in subsection (c) below. Both forecasting groups produced high, medium and low forecasts for use in Susitna planning studies. The merlh~"J1 fvtecast vJas used for determining base generation p1ans, with the high and low forecasts used in sensitivity analyses. (b) Electricity Demand Profiles This section reviews the historical growth of electricity consump- tion in the Railbelt and compares it to the national trend. Earlier forecasts of Railbelt electricity consumption by ISER, which were used in Susitna development selection studies, are also described. (i) Historical Trends Between 1940 and 1978, electricity sales in the Railbelt grew at an average annual rate of 1.5.2 percent. This growth was roughly twice that for t(,e nation as a whole. Table 8.65 shows U.S. and Alaska~ annual growth rates for different periods between 1940 and 1978. The historical growth of Railbelt utility sales from 1965 is illustrated in Figure B. 77. Although the Railbelt growth rates consistently exceeded the national average, the gap has been narrowing in later years due to the gradu a 1 maturing of the A 1 ask an economy. Growth in the Railbelt has exceeded the national average for two reasons: population growth in the Railbelt has been higher· than the national rate, and the proportion of Alaskan households served by electric utilities was lower than the U.S. average so that some g~owth in the number of customers occurred independently of population growth. Table B.66 compares U.S. and Alaskan growth rates in the residential and commercial sectors. The distribution of electricity consumption between resi- dential and commercial-industrial-government sectors has been fairly stable. By 1978, the commercial-industrial- government and residential sectors accounted for 52 percent and 47 percent respectively. In contrast, the 1978 nation- widr ~hares were 65 percent and·34 percent, respectively. Historical electricity demand in the Railbelt, disaggre- gated by regions, is shown in Table B.67. During the 5-2 • (ii) period from 1965 to 1978, Greater Anchorage accounted for about 75 percent of Railbelt electricity consumption fol- lowed by Greater Fairbanks with 24 percent and Glennallen- Valdez with 1 percent. The pattern of regional sharing during this period has been quite stable and no discernible trend in regional shift has emerged. This is mainly a result of the uniform rate of economic development in the Alaskan Railbelt. ISER Electricity Consumption Foreca~:s The methodology used by ISER to estimate e1ectr~ic energy sales for the Railbelt is summarized in this se.ction and the results obtained are discussed. Methodology The ISER electricity demand forecasting model concep- tualized in computer logic the linkage between economic growth scenarios and electricity consumption. The out- put from the model is in the form of projected values of electricity consumption for each of the three geographi- ca 1 areas of the Rai 1 belt (Greater Anchorage, Greater Fairbanks and Glennallen-Valdez) and is c1assified by fi~al use (i.e., heating, washing, cooling, etc.) and co~suming secto~ (commercial, residential, etc). The model produces ou~put on a five-year time basis from 1985 to 2010~ inclusive. The ISER model consists of several submodels linked by key variables and dt•iven by policy and technical assump- tions and state and national trends. These submodels are grouped into four economic models which forecast future levels of economic activity Knd four electricity consumption models which forecast the associated elec- tricity requirements by consuming sectors. For two of the consuming sectm·s it was not possible to set up com- puter models and simplifying assumptions were made. -Forecasting Uncertainty To adequately address the uncertainty associated with the prediction of future demands, a number of different economic growth scenarios were considered. These were formulated by alternatively combining high, moderate and low gro111th rates in the area of special projects ar.d industry with state government fiscal policies aimgd at stimulating either high, moderate or low growth. This resulted in a total of nine potent·ial growth scenarios 5-3 • .. for the state. In addition to these scenarios, ISER also considered the potential impact of a price reduced shift towards increased electricity demand. A short list of six future scenarios was selected. These con- centrated around the mid-range or 11 base casen estimate and the upper and lower a~\d extremes (see Table 8.68). -Demand Forecasts An important factor to be cons·idered "in gener·ation plan- ning studies is the peak power demand associated with a forecast of electric energy demand. The overall approach to derivation of the peak demand forecasts for the Railbelt region was to examine the available histor- ical data with regard to the generation of electrical energy and to apply the observed generation patterns to existing sales forecasts. Information routinely sup- plied by the Railbelt utilities to the Federal Energy Regulatory Commission was utilized to determine these load patterns. The first step involved an adjustment to the allocated sales to reflect losses and energy unaccounted for. The adjustment was made by increasing the energy al1ocated to each utility by a factor computed from historical sales and generation levels. This resulted in a gross energy generation for each utility. The factors determined for the monthly distribution of total annual generation were then used ';o distribute the gross generation for each year. The resulting hourly loads for each utility were added together to otcain the total Railbelt system load pattern for each forecast year. Table 8.69 summarizes the total energy generation and the peak loads for each of the low, medium, and high ISER sales forecasts, assuming moderate government expenditure. Adjusted ISER Forecast~ Three of the 1nitial ISER energy forecasts were con- sidered h~ ·generatiQn planning stud~es for development selection studies. lltese included the base case (f4ES-Gr4) or medium forecatt, a low forecast and a high forecast. me 1ow forecast was-rhat cor~esponding to the low economic growth as proposed by ISER with an adjustment for low government expenditure (LES-GL). The high forecast corresponded to the ISER high economic 5-4 .. •· fi .11 growth scenario with an adjustment for high government expenditure (HES-GH). The electricity forecasts summarized in Table B.69 rep- resent total utility generation and include projections for self-supplied industrial and military generation sectors. Included in these forecasts are transmission and distribution losses in the range of 9 to 13 percent depending upon the generation scenario assumed. These forecasts, rangir.g from 2.71 to 4.76 percent average annual growtho were adjusted for use in generation plan- ning studies. The self-supplied industrial energy primarily involves drilling and offshore operations and other activities which are not likely to be connected into the Railbelt supply system. This component, which varies depending upon generation scenario, was therefore omitted from the forecasts used for planning purposes. The military is likely to continue purchasing energy from the general market as long as it remains economic. However, much of their generating capacity is tied to district heating systems which would presumab1y continue operation. For study purposes, it was therefore assumed that 30 percent of the estimated military generation would be supplied from the grid system. The adjustments made to p0wer and energy forecasts for use in self-supplied industrial and mil~tary sectors are ref1ected in Table Be69 and in Figure B.78. The power and energy values given in Table B.70 are those develop- ed by ISER and used in the development selection studies. Annual growth rates range from 1.99 to 5.96 percent for very low and high forecasts with a medium generation forecast of 3.96 perce~t. (c) Battelle Load Forecasts As part of its study of Alaska Railbelt Electric Energy Alterna- tives (6) Battelle did extensive work in reviewing the 1980 ISER forecasts, methodology, and data, and produced a new series of forecasts. These forecasts built on the base of information and modeling established by ISER's 1980 wm k and, with the assistance of ISER, developed new models for forecasting Railbe1t economic activity and resulting electrical energy demands. The resulting forecasts were adopted directly for use in final generation planning studies under this feasibility study. 5-5 .. .. These revised forecasts included both an energy and peak capacity projection for each year of the study period (1982-2010). roe pro- jection left out portions of electrical demand which would be self-supplied, such as much of the military demand and some of the industrial demand. In addition, these forecasts took into account the conservation technology and market penetration likely to take place. Details of the Battelle forecasts and metho~ology are available in a report produced by Battelle in early 1982 (9). The demand forecasting process is summarized in the following three paragraphs. Figure B.79 shows the electricity demand forecasting process used by Battelle. The forecasting process contains two steps. The first step combines sets of consistent economic and policy assump- tions (scenarios) with economic models from the ISER to produce forecasts of future economic activity~ population, and households in the Railbelt region and its three load centers~ In the second step, these forecasts are combined with data on current end uses of electricity in the residential sector, data on the size of the Railbelt commercial building stock, data on the cost and perfor- mance of conservation; assumptions concerning the future prices of electricity and other fuels, and future uses of electricity to produce demand forecasts. The economic and population forecasts, energy use data, and other assumptions are all entered into a computer-based electricity demand forecasting model called the Railbelt Electricity Demand (RED) Model (7). The RED model generates forecasts of housing stock and commercial building stock and the price-adjusted intensity of energy use in both the residential and corrmercial (including government) sectors. It also adds estimates of major industrial electrical energy demand and miscellaneous uses such as street 1 i ght i ng. Tiiese forecasts are adjusted for specific energy conservation policies~ and then the major end-use sector forecasts are combined by the model into forecasts of future annual d~mand for electr·ic energy for each of the Rai1belt's load centers. The combined annual loads are adjusted by an annual load factor to estimate future annual peak demand by load centers Finally, the peak loads are added together and multiplied by a diversity factor {to adjust for the fact that peak loads for different load centers do not coincide) to derive peak demand for the Railbe1t. More detail on the RED model can be found in Reference 7~ The projected cost of power affects these forecasts. Because the size of demand for power affects the size, number, and cost of generating facilities that may have to be built to meet the demand (which in turn affects the cost of power), several passes through the RED model with constant economic assumptions and va~y­ ing costs of power are required to produce a final forecast. 5-6 The Battelle study produced numerous 1 oad forecasts which corres- ponded to different development plans. The plans varied due to different economic scenarios and costs of power. From these sep- arate forecasts, a high, medium and low forecast were selected for project planning and economic and financial feasibility studies. The Battelle forecasts are based on energy sales, and have there- fore been adjusted by an addition of an estimated 8 percent for transmission losses to arrive at the supply forecast to be used in generation planning. Table B.71 and Figure B.BO present the three Battelle forecasts which were prepared to bracket the range of electrical demand for the future. It should be noted that the load forecast figures vary in absolute values of peak demand and energy from those figures in the refer- enced Battelle studies. This minor variance (approximately 5-8 percent in the project development years) is due to the revision in the Battelle forecasts in 1982 after the feasibility v1ork on Susitna proceeded using December 1981 numbers. The Battelle forecasts were used in second stage generation plan- n·ing studies. The second stage studies focused on the economic and financial feasibility of the selected Susitna project and the sensitivity of the analyses to variation of key study assumptions. The differences between the earlier· ISER forecasts used in . development selection studies and the revised Battelle for-ecasts are not considered to be significant enough to have altered the conclusions of th~ earlier studies. The Railbelt generation plan- ning studies undertaken for Susitna feasibility assessment were based on the Battelle medium forecast. The high and low BattellP forecasts were used as a basis for sensitivity testing. No additional information on load patterns relative to monthly and daily shifting of load shapes was developed in the Battelle fore- casts. Thu>, the historical data developed for use with the 19&J ISER forecasts were also used with the Battelle forecasts. (d) Load Management and Conservation The Alaska Power Authority as a developer of power prqjects has not instituted any conservation rate design programs to effect loads. However, both the ISER and Battelle forecasts included a consideration of these measures. In addition, the ISER low forecast (Tables B.69 and B.70) was modified to reflect a higher degree of load modifying measures. (i) The resultant ISER forecasts in Table B.69 were made based on several projected conservation measures in place. These assumed measurPs resulted in lower forecasts than would be made if prevailing (1980) conditions were projected to continue. 5-7 • .. ~ , . . ,l -• '*' . • - • • • I ~ ~ . . . , . . -. . . ii For the residential sector, ISER assumed the federally~mandated efficiency standards for electrical home appliances would be enforced from 1981 to 1985 but that target efficiencies wou1d be reduced by 10 percent. Energy saving due to retrofitting of homes was assumed to be confined to single family residences and to occur between 1980 and 1985o Heating energy consumption was assumed to be reduced by 4 percent in Fairbanks, 2 percent in Anchorage and between 2 and 4 perc2nt in the Glennallen-Valdez areae Enforcement of mandatory construction or performance standards for new housing was assumed in 1981 with a reduction of the heat load for new permanent home construction by 5 percent. In the commercial-industrial-gover·nment sector, it was assumed by ISER that electricity requirements for new construction would be reduced by 5 percent between 1985 and 1990 and by 10 percent during the period 1990 to 2000. It v~ms assumed that retrofitting measures would have no impact. Since the ISER forecasts incorporated the impacts of these expected energy conservation measures but did not include load ntanagement, a low load forecast with high emphasis on load reduction measures was made. The purpose of this forecast would be to test gener·at ion plans during the development selection pha:;e. TI1e basis for this forecast was the ISER forecast~ further adjusted downward to account for load reduction measures. The programs of energy conservation and load management measures that were assumed to be implemented in addition to those included in the ISER forecast are the following: · • Energy programs provided for in the Alaska state energy conservation legislation; • Load management concepts not tested by utilities, inc1uding rate reform, to reflect incremental cost of service and load controls. The impact of state energy conservation legislation has been evaluated in a study by Energy Probe (10) which indicated that it could reduce the amount of electricitiy needed for space heating by 41 percent. Tt1e total growth rate in electricity demand over the 1980-2010 period would drop from an average of 3.98 percent per annum (projected by ISER in the MES-GM forecast) to 3.49 percent annum. Energy Probe indicated that the electrical energy growth rate could be reduced even further to 2.70 percent per annum with a conservation program more stringent than that presently contemplated by the state legisl~ture. 5-8 ,. .. .. ' ~ .... .., . . .. . . : . ' . . . . ' ~ ~ . . .~ ;. ~·. . . . . . ... . . . -. .""'· ~ 0 I Q The ISC:R low forecast case incorporates an annual growth rate of 2.71 percent. This rate would be reduced with enforcement of energy conservation measures more intensive than those present 1 y in the state 1 egis 1 ature. An annua 1 growth rate of 2.1 percent was judged to be a reasonable lower limit for electrical demand for purposes of this study. This represents a 23 percent reduction in growth rate which is similar to the reduction developed in the Energy Probe study. T~e implementation of load management measures would result 1n an additional reduction in peak load demand. The residential sector demand is the most sensitive to a shift of load from the peak period to the off-peak period. Over the 1980-2010 period, an annual growth rate for peak load of 2.73 percent was used in the low forecast case. With load management measures such as rate reform and load controls, this growth rate could be reduced to an estimated 2.1 percent. The annual load factor for year 2010 would be increased from 62.2 percent in the low forecast to 64.4 in the lowest case. The resultant adjusted low-load management and conservation forecast is presented in Table B.70. The forecast was used to check the development selection plans discussed in Section 1. Results of that analysis are presented in Table 8.12. (ii) The Battelle Railbelt Electric Power Alternative Study-(6) also reviewed in depth the impact of conservation impacts on load forecasts. The forecoasts made for the base plans, such as those produced in Table B.71 take into account substantial conservation of electricity because of the increase in price of electricity during the time horizon of th~ study. Since the forecasts are an end product of an iterative process of demand and price analysis, they include a market penetration of conservation technologies which · improve the efficiency of end use of electricity. This would include a variety of techniques such as weatherstripping, set-back thermostats, water-heater jackets. These measures which are expected to be adopted as a matter of course are the low initial investment, quick-payback conservation methods. The Battelle Study also studied a specific plan ·tn which conservation alternatives received greater emphasis than the base plan. The plan also included a high use of renewable energy sources. To achieve the plan, a maximum technical contribution of conservation program was assumed which goes beyond the market-i.nduccd conservation included in the base plan. 5-9 L In this conservation program, the State of Alaska is assumed to provide a grant program to residential consumers to offset the initial investment cost of four technologies with higher initial cost and high eDergy payoff. The four selected technologies are: super insulation of buildings, passive solar designs for space heating, active solar hoc water heating, and wood-fired space heatinge Because less information is available about specific end uses of electricity in the business sector, the conservation supply plans relied on estimates of maximum average electrical conservation of about 35 percent in the business sector and corresponding estimates of minimum life cycle energy costs. The initial capital cost of achieving this maximum technical saving was then reduced to zero by an assumed business sector grant program, resulting in full technical savings. The resultant forecasts of peak demand and annual energy are presented in Table 8.72. The table compares the Battelle base plan forecast to the high conservation and rene\table resource forecast for low, medium and high conservation. As discussed in (c) of this subsection, these forecasts vary slightly from the forecasts used in Susitna project planning studies, due to adjustments made after completion of the lattera Additionally, the forecasts are for end use demand and should be increased by approximate 1 y eight pet"cent for line losses and reserve requirements. These forecasts are those developed with the Susitna project part of the generation plan. They are slightly higher than those of similar economic scenarios which do not include Susitna due to the price elasticity of the forecast model. 5.2 -Market and Price for Watana Output in 1994 It has been planned that Watana energy will be supplied at a single wholesale rate on a free market basis. This requires, in effect, that Susitna energy be priced so th&t it is attractive even to utilit1es with the lowest cost alternative source of energy. On this basis it is estimated that for the marketable 3315 GWh of energy generated by Watana in 1994 to be attractive, a price of 145 mills per kWh in 1994 dollars is required. Justification for this price is illustrated in Figure 8.81. Note that the assumption is made that the only capital costs which would be avoided in the early 1990s would be those due to the addition of new coal-fired generating plants (i.e., the alternative 2 x 200 MW coal-fired Beluga station). The financing considerations under which it would be appropriate for Watana energy to be sold at approximately 145 mills/kWh price are pre- sented in Exhibit D; however, it should be noted that some of the energy which would be displaced by Watana•s 3315 GWh would have been generated at a lower cost than 145 mills, and utilities might wish to 5-10 delay accepting it at this price until the escalating cost of natural gas or other fuels made it more attractive. A number of approaches to the resolution of this problem can be postulated, including pre-contract arrangements. (a) Contractual Preconditions for Susitna Energy Sale It will be necessary to contract with Railbelt utilities for the purchase of Susitna capacity and energy on a basis appropriate to support financing of the project. Pricing policies for Susitna output are assumed to be constrained by both cost (as defined by State of Alaska Senate Bill 25) and by the price of energy from the best thermal option. Marketing Sus itna • s output within these tw·i n constraints waul d ensure that all state support for Susitna flowed through to con- sumers and under no circumstances were prices to consumers higher than they would have heen under the best thermal option. In addi- tion, consumers would also obtain the long-term economic benefits of Susitna•s low cost energy. (b) Market Price for Watana Output 1995~2001 After its initial entry into the system in 1994, the price and market for the 3315 Gwh of Watana output is consistently upheld over the years to 2001 by the projected 20 percent increase in total demand over this period. There would, as a result, be a 70 percent increase in cost savings compared with the best thermal alternative. The increasing cost per unit of output from a system without Susitna is illustrated in Figure B.82o (c) Market and Price for Watana and Devil Canyon Output in 2003 A diagramatic analysis of the total cost savings which the com- bined Watana and Devil Canyon output will confer on the system compared with the present thermal option in the year 2003 is shown in Figure B.83. These total savings are divided by the energy contributed by Susitna to indicate a price of 250 mills per kWh as the maximum price which can be charged for Susitna output. Here again, the problem of competing with low~r cost combined cycle, gas turbines, etc., will have to be addressed; however, this prob- lem is likely to be short term in nature, since by this time period these thermal power facilities will be approaching retire- ment. Only about 90 percent of the total Susitna output will be absorbed by the system in 2002; the balance of the output will be progress- 5-11 a:·· I . (d) ively absorbed over the following decade. This will provide increasing total savings to the system from Susitna with no associated increase in costs. Potential Impact of State Appropriations In the preceding paragraphs the maximum price at which Susitna energy could be sold has been identifiedG Sale of the energy at these prices will depend upon the magnitude of any proposed state appropriation designed to reduce the cost of Susitna energy in the earlier years. At significantly lower prices it is likely that the total system demand will be higher than assumed. This, com- bined with a state appropriation to reduce the energy cost of Watana energy, would make it correspondingly easier to market the output from the Susitna development; however, as the preceding analysis shows, a viable and strengthening market exists for the energy from the development that would make it possible to price the output up to the cost of the best thermal alternative. (e) Conclusions Based on the assessment of the market for power and energy output from the Susitna Hydroelectric Project, it has been concluded that, with the appropriate level of state appropriation and with pricing as defined in Senate Bill 25, an attractive basis exists, particularly in the long term, for the Railbelt utilities to derive benefit from the project. It should be recognized that contractual arrangements covering purchase of Susitna output will be an essential precor.aition for the actual commencement of pro- ject construction. These contractual arrangements will be pursued during the licensing and design phase of the project. 5.3 -Sale of Power Electrical energy from the Susitna Hydroelectric Project will be sold to utilities serving the Anchorage/Fairbanks net. The potential customers for Susitna power utilities in the Railbelt inc 1 ude: -Fairbanks Municipal Utility System; -Homer Electric Association; -Anchorage Municipal Light & Power Department; -Chugach Electric Association; -Golden Valley Electric Association; -Matanuska Electric Association; and -Seward Electric System A more detailed discussion of marketing can be found in Reference 8. 5-12 • .. • n II ti ' 1 ') I I 6 -FUTURE SUSITNA BASIN DEVELOPMENT .. • I. ,. . 6 -FUTURE SUSITNA BASIN DEVELOPMENT The Alaska Power Authority has no current plans for further development of the Watana/Devil Canyon system and no plans for further water power projects in the Susitna River Basin at this time. Development of the proposed projects would preclude further major hydroelectric development in the Susitna basin, with the exception of major storage projects in the Sus i tna basin headwaters. A 1 though these types of plans have been considered in the past, they are neither active nor anticipated to be so in the foreseeable future. 6-1 ] _I I I. I f f REFERENCES 1. Acres American Inc., Susitna Hydroelectric Project, Development Selection Report, prepared for the Alaska Power Authority, December 1981. 2. Woodward-Clyde Consultants, Final Report on Seismic Studies for Susitna Hydroelectric Project, prepared for Acres American Inc., February 1982. 3. Acres American Inco, Susitna Hydroelectric Project, 1980-81 Geotechnical Report, prepared for the Alaska Power Authority, February 1982. 4. Acres American Inc., Susitna Hydroelectric Project, Feasibility Report, Vol. 1, prepared for the Alaska Power Authority, March·- 1982. 5. General Electric Company, OGP5 User 1 s Manual, May 1979. 6. Battelle Pacific Northwest Laboratories, Railbelt Electric Power Alternatives Study: Evaluation of Railbelt Electric Energy Plans, prepared for the Office of the Governor, State of Alaska, August 1982. 7. Battelle Pacific Northwest Laboratories~ The Railbelt Electricity Demand (RED) Model Specifications Report, prepared for the Office of the Governor, State of A1 aska, Augu'~t ~ ~82. 8. Ac~es American Inc., Susitna Hydroelectric Project Reference Report, Economic, Marketing and Financial Evaluation, prepared for the Alaska Power Authority, April 1982. 9. Battelle Pacific Northwest Laboratories, Alaska Economic Projectsion for Estimating Requirements for the Railbelt, prepared for the Office of the Governor, State of Alaskao 10. Energy Probe, An Evaluation of the ISER Electricity Demand Forecast, July 1980. 11. R&M Consultants, Susitna Hydroelectric Project, Regional Flood Studie~, prepared for Acres American Inc., December l98l. 12o Acres American Inc. and Terrestrial Environmental Specialist, Inc., Transmission Line Selected Route, prepared for the Alaska Power Aut~ority,-~arch 1982. 13. R&M Consultants, Terrain Analysis of the North and South Interti@ Power· Transmission Corridors, prepared for Acres ,LU-nerican Inc., - November 19S1. fJ· ~. ~.: ~- L 'I J 'I .B B B REFERENCES (Continued) 14. Acres American Inc, Susitna Hydroelectric Project, Feasibility Report, Vol. 4, prepare forte Alas a Power Authority, Marc 1982. 15. Acres American Inc., Susitna Hydroelectric Project, Access Route Selection Report, prepared for the Alaska Power Authority, March T9B2. - 16. Commonwealth Associates Inc., Anchorage-Fairbanks Transmission I ntert i e-Tr ansmi ss ion System D"at a, prepared for the A 1 ask a Power Authority, November 1980. • .. .. • TABLE 8.1: POTENTIAL HYDROELECTRIC DEVELOPMENT Cap I tal Average 1 Economic Dam Cost Installed Annual Cost of Source Proposed Freight Upstream $ ••1llllon Capacity Energy Energy of • Site Type Ft. Regulation ( 1980) (MW) Gwh $/1000 kWh Data Gold Creek 2 FIll 190 Yes 900 260 1, 140 37 USSR 1953 Olson • (Sus ltna II> Concrete 160 Yes 600 200 915 'Zt USBR 1953 Jl KAISER 1974 COE 1975 Dev II Canyon Concrete 675 th 830 250 11420 27 This Study Yes 1, 000 600 2, 980 17 " H lgh Dev II Canyon II (Susftna I) FIJI 855 No 1, 500 800 3.,540 21 II Dev II Creek 2 Ff II Approx th 850 Watana Fill 880 No 1, 860 800 3, 250 2 II Susltna Ill Fill 670 No 1 ,.390 350 1 ,5Fcf': 41 II Vee Fill 610 No 1, 060 400 1;,370 37 II 2 Fill 185 No 5304 55 180 124 Maclaren II Denali Fill 230 No 480 4 60 245 81 " Butte Creek 2 FIll Approx No 40 13o3 USSR 1953 150 2 Fill Approx 6 22 3 USSR 1953 Tyone 60 Notes: ( 1) Includes AFOO, Insurance, Amort I zatfon, and Operation and MaIntenance Costs. (2) No detailed engineering or anergy studies undertaksn as part of this study. (3) These are approximate estimates and serve only to represent the potential of these r~o damsltes In perspective. ( 4) Inc I ude es·l" r mated costs of power genera ... r I on fac Ill ty • C'* ,. -~ ~- • • • ~~~-~f;'-c:_-, ,.-.-·-,___ ~-~ c~-'=l [~·-··.i ~--J rr;L"; !:C:J llCIW D:J ~ ~ Dm '" ... . TABLE B~2 -COST COM~ARISONS DAM _ A c:;:. E s 19~0:: o T A E R s Instal led Captf~l Cost -Instal led Capital Cost SOurce and ---·--S--It~e ___________ T~y.p_e ____ ~C~a.p~ac~l~t~~-~--MW~-----S~m~l~l~ll~o~n ____ _.C~a.p~ac~l~t~~----MW~-----~$~m~l~l~l~lo~n~--~q-~-te~o~f_D~a-t~a-- Gold Creeh Filt 2601 Olson (Sus ltn~ II) Concrete Dev f I Canyon F II I Concrete Arch Concrete Gravity High Devil Canyon FIJI (Sus ttna 1) Dev! I Creek Fill Wat~na Susltna Ill Vee Maclaren Danai I Notes: Ft II FIJI FJ I I Fill FIJI .600 800 800 350 400 55 60 1,000 1,500 1,860 1,390 1,060 530 480 776 776 700 1CJ2 445 t-One 890 550 630 910 1,480 1, 630 770 500 (1) Dependable Capacity (2) Excluding Anchorage/Fafrban~~ transmission lntertle, but Including local access and tr~nsmlssfon • USRB 1968 COE 1975 COE 1975 COE 1978 COE 1975 COE 1978 KAISER 1974 COE 1975 COE 1975 Jlllll :-.. -· , . . I I I I I I I I I 11 IJ u I L !;c. TABLE 8.3: DAM CREST AND FULL SUPPLY LEVELS Staged full Dam Average Dam Supply Crest Tat I water Site Construction Level -F-t. Level -F-t. Level -ft. Gold Creek t-0 870 880 680 Olson No 1,020 1,030 810 Portage Creek fob 1, 020 1, 030 870 Dev ll Canyon - I ntermed tate height No 1,250 1,270 890 Dev II Canyon - full height tb 1,450 1,470 890 High Devil Canyon '-No 1, 610 1,630 1,030 No 1, 750 1, 775 1, 030 Watana Yes 2_,000 2,060 1,465 Stage 2 2,200 2,225 1,465 SusJtna I I I No 2,340 2,360 1, 810 Vee No 2,330 2,350 1, 925 Maclaren No 2,395 2,405 2,300 Denali tb 2, 540 2,555 2,405 Notes: (1) To foundation level. • Dam He Jght 1 ft .. 290 310 250 465 675 710 855 680 880 670 610 185 230 .. • 1) 2) 3) 4) 5) 6) 7) 8) 9) f' ~ Item Lands, Damages & Reservoirs Diversion Works MaIn Dam Auxi llary Dam Power System SpIll way System Roads 3nd Bridges Transmission Ltne Camp Fecllltles and Support 10) Mtscellanaous 1 11) Mobilization and Preearatlon Subtotal Cont!ngency (20%) Engineering and Owner's Administration (12~) TOTAL Notgs: Dev f I Canyon 1470 ft Crest 600 MW 26 50 166 0 195 130 45 10 97 8 30 757 152 91 1000 TABLE B.,4 -CAPITAL COST ESTIMATE SU~RIES SUS IT Nl\ BAS I N DN-1 SO. I EMES COST I N $M I!.Li ON 1 J80 High Devil Canyon Watana Susltna Ill 1775 ft Crest 2225 ft Crest 2360 ft Crest 800 MW 800 MW 330 MW 11 46 13 48 71 88 432 536 398 0 0 0 232 244 140 141 165 121 68 96 70 to 26 40 140 160 130 a 8 8 47 57 45 1137 . 1409 1053 227 282 211 136 169 126 1500 1860 1390 (1) Includes recreational fac II It I es, buildings and grounds and permanent operating equipment. .... i' Vee Maclaren 2350 ft Crest 2405 ft Crest 400 MW No eower 22 25 31 118 183 106 40 0 175 0 74 0 80 57 49 0 100 53 8 5 35 15 803 379 161 76 96 45 1060 500 Denali 2250 ft Crest No eower 38 112 100 0 0 0 14 0 50 5 14 333 67 40 440 f I' r I f . I· l Total Demand Cap. Energy Run MW GWh 400 • 1750 2 800 3500 3 1200 5250 4 1400 6150 TABLE B.5 -RESULTS OF SCREENING t~DEL Optimal Solution Max. lnst. Site Water Cap. Names Level MW Hiah 1580 400 Devtl Canyon High Devil 1750 800 Canyon Watana 2110 700 Devi I 1350 500 Canyon TOTAL 1200 Watana 2150 740 Devil 1450 660 Canyon Total Cost $ ml Ilion 885 1500 1690 800 2490 1770 1000 . ,. First Suboptimal Solution Max. lnst. Site Water Cap. Names Level MW Devil 1450 400 Canyon Watana 1900 450 Devil Canyon 1250 350 TOTAL BOO High 1750 800 Devil Canyon Vee 2350 400 TOTAL 1200 N 0 SOLUTION Second Suboptimal Soultton Total Max. lnst. Total Cost Site Water Cap. Cost $ ml 1.1 I on Names Level MW $ mill Jon 970 Watana 1950 400 980 1130 Watana 2200 800 1860 710 ie1o 1500 High 1750 820 1500 Devt I Canyon 1060 Susitna 2300 380 1260 Ill 2560 TOTAL 1200 2760 N 0 S 0 L U T I 0 N f,. r 1 t· l 1 ~ l ~ LJ r ' I_ I JJ:..' .. L TABLE 8.6: INFORMATION ON THE DEVIL CANYON DAM AND TUNNEL SCHEMES Dev II Canyon . Tunnel Schema Item Dam 1 2 3 Reservoir Area (Acres) 7,500 320 0 3,900 River Milas Flooded 31.6 leO 0 15.8 Tunnel Length (Milas} 0 27 29 13.5 Tunnel Vslume ( 1000 Yd ) 0 t 1, 976 12,863 3, 732 Compensating Flow Release (cfs) 0 1, 000 1, 000 1, 000 Reservoir Volume (1000 Acre-feet) l, 100 g.:; -350 Dam Haight (feet) 625 75 -245 T yp i cat Da II y Range of Discharge 4,000 From Dev i I Canyon 6..,000 4, 000 8,300 Powerhouse to to to to (cfs) 13,000 14,000 14,000 8..,900 Approximate Maximum 03 J I y Fluctuations in Reservoir (feet) 2 15 -4 Notes: 3 Estimated, above existing rock elevation. . . . . . c> "' •• ~ . . . . : • A . . .. • ., 4 0 0 29 5, 131 1, 000 - - 3,900 to 4,200 \ - .. .. • TABLE 8.7-DEVIL CANYON TUNNEL SCH~1ES COSTS, POWER OUTPUT AND AVERAGE ANNUAL ENERGY Instal led . Dev II Canyon caeacl~ (MW) Increase 1 In Average Annual Watanavll Canyon Instal led Capacity Energy Stage Tunnel (MW) (Gwh) STAGE 1: Watana Dam 800 STAGE 2: Tunnel: -Scheme 1 800 550 550 2,050 -Scheme 22 70 1,150 420 4,750 -Scheme 3 850 330 380 2,240 -Scheme 4 800 365 365 2,490 Note -(\) Increase over single Watana, 800 MW development 3250 Gwh/yr (2) Includes power and enerQt produced at re-reguiatlon dam (3) Energy cost ls based on an economic analysis (I.e. using 3 percent Interest rate) 1 Tunnel Scheme Increase In Average Total Project Annua I Energy Costs (Gwh> $ Million ... -- 2,050 1980 1, 900 2320 2,180 1220 890 1490 3 Cost of Addltion'l Energy (mills/kWh> .·.--- 42.6 52.9 24.9 73.6 l' f t l l \ I l' I !• h I l·· I I ! .. TABLE B.S -CAPITAL COST ESTIMATE. SLMMARIES TLNNEL S(}{EMES COSTS IN $MILLION 1980 I Two 30 ft one 40 ft Item dla tunnels dla tunnel Land and damages 1 reservoir clearing 14 14 Divers ion works 35 35 B Re-regulation dam 102 102 Power system 680 576 (a) Main tunnels 557 453 I (b) lntake 1 powerhousa, tailrace and switchyard 123 123 Secondary power station 21 21 I Spillway system 42 42 Roads and brIdges 42 42 f Transmission lines 15 15 Camp facilities and support 131 117 f Ml scell aneous* 8 8 Mobilization and 2reearatton 47 47 TOT/\ L CONSTRLCT I ON COST t, 137 1, 015 e Contingencies (20%> f 227 203 Enplneering, and Owner's Administration 136 122 f TOTAL PROJECT COST 1,500 1,340 TABLE Be 9. SUS ITNA DEVELOPMENT PLANS TABLE 8.9 (Continued) Cumu I e.t I ve St~ge/lncrementa! Data S~stem Data Annual Maximum Energy Capital Cost Ear· I t est Reservo t r Seasonal Product ion Plant $Mil I Ions On-1 lne FuJI Supply Draw-Firm Avg. Factor Plan Stage Construction 1 % (1980 values) Date Level -ft. down-ft. Gw-1 Gw-i 2. 1 High Devil Canyon 1775 ft 800 MW 3 1500 1994 1750 150 2460 3400 49 2 Vee 2350 ft 400 MW 1060 1997 2330 150 3870 4910 47 TOTAL SYSTEM 1200 MW . 2560 2.2 High Devil Canyon 3 1630 ft 400 MW 1140 1993 1610 100 1770 2020 58 2 Htgh Devil Canyon add 400 MW Capac Jty raise dam to 1775 ft 500 1996 1750 150 2460 3400 49 3 Vee 2350 ft 400 MW 1060 1997 2330 150 3870 4910 47 TOTAL SYSTEM 1200 t-1W 2700 t t 2.3 High Devil Canyon I 3 1775 ft 400 MW 1390 1994 1750 150 2400 2760 79 2 High Devil Canyon i add 400 MW capacity 140 1994 1750 150 2460 3400 49 ! 3 Vee zoz~-ft 400 MW 1060 1997 2330 150 3870 4910 47 l TOTAL ;, JT8-1 1200 MW 2590 I f I 3. 1 1 Watana 2225 ft 800 MW 1860 1993 2200 150 2670 3250 46 I 2 Watana add 50 MW t tunnel 330 MW 1500 1995 1475 4 4890 5430 53 I TOTAL SYSTEM 1180 MW 3360 f ' r l r \ l t )r • f· f· l • .. t· / • TABLE 8.9 (Continued) Cumu latlve Stage/Incremental Data System Date Annua I Maximum Energy Capital Cost Earliest Reserv~!r Seasonal Production Plant $ M I I lions On-line F•.!: I Supply Draw-Firm ·Avg. Factor Plan Stage Constr·uctlon 'j (1980 values) Date Level -ft .. down-ft. G\ti G\tt % 3. 2 Watana 2225 ft 400 MW 1740 1993 2200 150 2670 2990 85 2 Watana add 400 t~ capacity 150 1994 :l200 150 2670 3250 46 3 Tunnel 330 MW add 50 MW to Watana 1500 1995 1475 4 4690 5430 53 -3390 4.1 Watana 2'~25 f1" 400 MW 1740 1995 3 2200 150 2670 2990 85 2 \~atana add 400 MW capacity 150 1996 2200 150 2670 3250 46 3 HIgh Dav II Canyon 1470 ft 400 MW 860 1998 1450 100 4520 5280 50 4 Portage Creak 1030 ft 150 MW 650 2000 1020 50 5110 6000 51 TOTAL SYSTEM 1350 MW 3400 NOTES: (1) Allowing for a 3 year overlap construction period between major dams. (2) Plan 1.2 Stage 3 Is lass expansive than Plan 1.3 St~ga 2 due to lower rooblllzatlon costs. (3) Assumes FERC license can be fl I ad by June 1984, lao 2 years later than for the Watana/Dav II Cenyon PI an 1 • ... ~ -- j I I: t r r ~ ,------------ TABLE 8.10. SUSITNA ENVIRONMENTAL DEVElOPMENT PLANS Cumulative Stage/Incremental Data S~stem Data Annual Maximum ·Energy Capital Cost Earl test Reservoir Seasonal Product ton Plant $ Mt II ions On-line Full Supply Draw-Firm Avg .. Factor Plan Stage Construction ( 1980 va I ues ) Date 1 Level -ft. down-ft G\!!-1 GWH. ,; E 1. 1 Watana 2225 ft 80CMW and Ra-Regulation Dam 1960 1993 2200 150 2670 3250 46 2 Dev II Canyon 1470 ft 400'4W 900 1996 1450 100 5520 6070 58 TOTAL SYSTEM 120CMW "'2800 l E 1. 2 1 Watana 2060 ft 40CMW 1570 1992 2000 100 1710 2110 60 I 2 Watana raise to ~ 2225 ft 360 1995 2200 '150 2670 2990 85 l 3 Watana add 40CMW I capacity and l l Re-Regulatlon Dam 2302 1995 2200 150 2670 3250 46 ! I 4 De-:! I Canyon 1470 ft f 40CNW 900 1996 1450 100 5520 6070 58 i ! TOTAL SYSTEM 120CMW ~ l l l Et.3 1 Watana 2225 ft 40CMW 1740 1993 2200 150 2670 2990 85 l l 2 Watana add 40Q.1W ! capacity and ! Re-Regulatlon Dam 250 1993 2200 150 2670 3250 46 I I I 3 Dev II Canyon 14 70 fT I l 400 MW 900 1996 1450 100 5520 6070 58 r TOTAL SYSTEM 120a.1W "'2890 ! t ! r t l ! -1 I t f f • ·~ . rr rr·--.,..,_.., IL __ ·-·-·- TABLE B.10 (Contlnuedl Cumu latlve S-t:_~e/l.ncrementa I Data System Data Annual Maximum Energy Capital Cost Earliest Reservoir Seasonal Product I on Plant $Millions On-line Full Supply Draw-Firm Avg. Factor Plan 1 Stage Construction (1980 values) o~~te Level -'ft. down-ft. G'M GWH % E 1. 4 Watana 2225 ft' 400\1\i 1740 1993 2200 150 2670 2990 85 2 Dev II Canyon 1470 ft 40CMw· 900 1996 1450 100 5190 5670 81 --TOTAL SYSTEM 8Qa-1W 2640 E2. 1 ~ High Devil Canyon 1775 H· 80CJ.1W .:md 3 Re-Regulatlon Dam 1600 1994 1750 150 2460 3400 49 2 Vee Z350ft ~Oav1W 1060 1997 2330 150 • 3870 4910 47 TOTAL SYSTeM 120<MW 2660 E2 •. 2 High Devil Canyon '1630 ft 40CMW 3 1140 1993 1610 100 1770 2020 56 2 HIgh Oav II Canyon raise dam to 1775 ft add 40CM\~ and Re-Regul atlon Dam 600 1996 1750 150 2460 3400 49 3 Vee 2350 ft 400 MW 106G 1997 2330 150 3870 4910 47 TOTAL SYSTe-1 1200v1W .2800 E2. 3 High Devil Canyon 1775 ft 40CMW 1390 3 1750 150 1994 2400 2760 79 2 H f.gh Dev II Canyon add 40CMW capac lty and Re-Regul a'rlon ~· Dam 240 1995 1750 150 2460 3400 49 ,. 3 Vee 2350 ft 400V.W 1060 1997 2330 150 3870 4910 47 TOTAL SYSTEM 1200 2695' TABLE 8.10 (Continued) Cumulative Stege/lncremeJttal Oat a S:tstem Data Annual Maximum Energy Capital Cost Earliest Reservoir Seasonal Production Plant $ M II lions On-line Ful I Supply Draw-Firm Avg. Factor Plan Sta a Construction (1980 values) 1 Level -ft. G\'M G'tl-t Date down-ft. E.Zt. 4 High Devil Canyon 1 755 ft 40CMW 1390 1994 3 1750 150 2400 2760 79 2 H l gh Dev t I Canyon add 400MW capacity and Portage Creek Dam 150 ft 790 1995 1750 150 3170 4080 49 3 Vee 2350 ft 40CMW 1060 1997 2330 150 4430 5540 47 TOTAL SYSTEM 3240"" E3. 2 Watana 2225 it 40CMW 1740 1993 2200 150 2670 2990 85 2 Wa,tana add 400 MW capac 1 ty and Ra-Regulatlon Dam 250 1994 2200 150 2670 3250 46 3 Watana add SCMW Tunnel Scheme 33CMW 1500 1995 1475 4 4890 5430 53 TOTAL SYSTEM 118CM\i "3490"" E4. 1 1 Watana 2225 ft 40a4W 1740 19953 2200 150 2670 2990 85 2 Watana add 400'4\i capacIty and Re-Ragulatlon Dam 250 1996 2200 150 2670 3250 46 3 HIgh Dav II Canyon 1 470 ft 40CMW 860 1998 1450 100 4520 5280 50 4 Portage Creek l 030 ft 15CMW 650 2000 1020 50 5110 6000 51 TOTAL SYSTEM 1350 MW 1300 NOTES: (1) AI lowing for a 3 year overlap constructiQn period between maJor dams. (2) Plan 1.2 Stage 3 Is less expensive than Plan 1.3 Sta~e 2 due to lower mobilization costs. (3) Assumes FERC license can be flied by June \984, Ia. years later than for the Watana/Devll Canyon Plan " l ' 1. - 'II d d l ! -i \ I ! ! I l l ! f. 1 l t I I l .... ( I TABLE 8.11 -RESULTS OF ECONOMIC ANALYSES OF SUSITNA PLANS -MEDIUM LOAD FORECAST - Susl=fna Oeveloement Plan Inc.: lns=falled Capacity (MW) by lotal System Total System On I i ne Dates Category in 2010 Installed Present Remarks Pertaining to Plan Stages OGP5 Run Tfiermal Ry<Iro . -Capacity In Worth Cost the Susltna Basln No .. t 2 '3 4l I de No. -cQal Gas 011 Other Sus ltna 2010-MW $ Million Develo~ment Plan E1. 1 1993 2000 LXE7 300 426 0 144 1200 2070 5850 E1. 2 1992 1995 1997 2002 L5Y9 200 501 0 144 1200 2045 6030 E 1.3 1993 1996 2000 L8J9 300 426 0 144 1200 2070 5850 1993 1996 L7N7 500 651 0 144 800 2095 69€0 Stage 3, Dev t I Cl'Jnyon Dam not constructed 1998 2001 2005 LAD7 400 276 30 144 1200 2050 6070 Delayed Implementation schedule E 1.4 1993 2000 LCK5 200 726 50 144 800 1920 5890 Total development 1 tml ted to 800 MW I Modi fled EZ.l 1994 2000 LB25 400 651 60 144 800 2055 6620 HIgh Dev 11 Canyon limited to 400 MW E2.3 1 1993 1996 2000 L601 300 651 20 144 1200 2315 6370 1993 1996 LE07 500 651 30 144 800 2125 6720 Stage 3, Vee Dam, not constructed Mod !fled E2.3 1993 1996 2000 LEB3 300 726 220 144 1300 2690 6210 Vee dam rep I aced by Chakachamna dam 3.1 1993 1996 2000 L607 200 651 30 144 1160 2205 6530 Special Capital cost of tunnel 3. 1 1993 1996 2000 L615 200 651 30 144 1180 2205 6230 reduced by 50 percent E4.1 1995 1996 1998 LTZ5 200 576 30 144 1200 2150 6050 Stage 4 not co1~structed NOTES: (ll Adjusted to Incorporate cost of re-regulatlon dam • ..,_ II • ~ • • ~ • • I ............. -................ -. TABLE B.13 -ANNU&.L FIXED CARRYING CHARGES Economic Parameters r l Economic Cost of Life f.bney Amortization l.1surance Pro.}ec1" T}:~e -Years % % % Thermal -Gas Turbine (Oil Fired) 20 3.00 3. 72 0.25 -Diesel, Gas Turbine (Gas Ft red) and f ' , f Large Steam 3.00 Turbine 30 410 0. 25 -Small Steam Turbine 35 3.00 1.65 0.25 Hydrqpower 50 3.00 0.89 0.10 - .. TABLE B. 14 -SUMW\RY OF THERM-\L GENERAl I NG RESOLRCE PLANT PARAMETERS P LA fil 1 1 '(" Cu7\[ -F I REO STEAR c()161 NED G\S Parameter CYCLE Tl.RB INE DIESEL 500 f.1W 250 MW 100 MW 250 MW 75 Mil 10 M\'l Heat Rate <Btu/kWh) 10,500 10,500 10,500 8,500 12,000 11' 500 O&M Costs fixed O&M ($/yr/kW) 0. 50 1. 05 1.30 2.75 2 .. 75 o. 50 Variable O&M ($jMWH) 1.40 1. 80 2.20 0.30 0.30 5.00 Outages Planned Outages <%> 11 11 11 14 11 1 Forced Outages ($) 5 5 5 6 3.8 5 Construction Period (yrs) 6 6 5 3 2 Start-up Ttme !yrs) 6 6 6 4 4 Total Ca¥1tal Cost ($ mil lort) Rat I belt: 175 26 1. 7 Beluga: 1,130 . 630 290 ~ Ca2ital Cost (.$/kW) 1 Rall bolt: 728 250 778 Beluga: 2473 2744 3102 Notes: ( 1) Inc I udlng AFOC at 0 percent escal atlon and 3 percent· Interest. TABLE B.15-ECONOMIC BACKUP DATA fOR EVALUATION OF PLANS Total Present Worth Cost for l98l -2040 ~ PeriodS Million <%Total) Generation I an Genera-tion I an neratton I an W l th H t gh Dev II Wlth Watana -WiTh Watana -All Thermal Parameter Canyon -Vee Devi I, Canyon Dam Tunnel Generatl2n Plans Capt tal Investment 2800 (44) 2740 (47) 3170 (49) 2520 (31) 3220 (50) 2780 (47) 3020 {46) 5240 (64) fuel Operation and Malntenance 350 (6) 330 (6) 340 (5) 370 (5) 6370 (100) 5850 (100) 6530 (100) 8130 (tOO) iOTAL: - .. • • 11\BLE e.16 -ECONOI~IC EVALIJIIliOH Of OEVIL CANYON DAM liND lUNNEL SCHEtJ£5 1\ND WAlANI\/I)EVIL CAIIYOII AIID HIGH DEVIL CANYOtlf/EE PLAIIS ------ resenT wor o eT one I < m II onl o toTal generation Remarks . . .!~tem costs jor the: _ --oev11 t!onyon bam o'ler wafano70ev l I canyon Dams over ~~~~~~~~~~~~~~~~~~~~~~~~t~h~e~l~Pin~n~e~t~S~ch~e~~~~-~-~ theHl~ Dev\l Canyon~ee Da~ 680 --------------~--~----------- Economic ranktng: Devl\ Canyon dam schema \s superlor to Tunnel scheme• WaTanafOevl\ Canyon dam p\an ts superior to the High Oev 1 \ Canyon dam~ ee dam pI an. ECONOMIC EVALUAl\ON: -=Base Case SENS\TlV\lY ANALYSES: -Load Growth -Capital Cost Estimate -Period of Economlc Analysis -0 t scount Rate -Fue\ Cost -Fuel Cost Escalatlon -Economic Thermal P\ant Life Low Hlgh Period shortened to {1980-2010) 5~ 8% {tnterpotated) 9!t 80% baste fuel cost O% tue\ ascatatton O% coal escatatton 50% extension O% extens ton · 650 N.A. 210 1040 . Higher uncerTainty assoc-Higher uncertainty associaTed ~ITh tated w\th tunnel scheme.. H.o.c./Vee plan• 160 230 As boTh the capital and fuel costs associated with the tunnel scheme and H.o.c.f/ea Plan are higher than for Watana/Oevll Canyon plan anY chanJOS to these parameters cannot reduce the Oevll Canyon or Watana/OeVII Canyon net benefit to beloW zero. The net benefit of the Watana/Devl\ Canyon plan remains pos\ttve tor the range of toad forecasts considered• No change in ranking• Higher cost uncerta\nttes associ- ated wtth higher cost schemes/plans. Cost uncertaintY therefore does not aftect econom1c ranklng• Shot"'ter per lod of eval uat ton decreases economlc dtfferenceso Ranking remains unchanged· Ranking rematns unchanged· TABLE 8.17 -ENVIRONMENl.AL EVALlJ.A.TION OF DEVIL CANYON [)AM AND TUNNEL SCHEME ~~~~--~~~~~~~~~~~~~~~~~~---Scheme Judged 1o have Appraisal the least potential Impact Environmental (Differences In lm~~palc:t~. ----------~ldte~nutJtlf~lc~a~t~lo~n~------------_1A~~~~~~~~~----------~1 ~un~n~e~1------~0C~--------~A:..!.t.!..tr!..!-!1 b~u~t~e _____________ ...:C::.:o~n!::c:.:::e!..rn:.:;s::.,_ ________ ...:o:::.;f:.......:tw.::.;o sche~s) of d I tterence Ecological: -Downstream Fisheries and Wildlife Resident Fisheries: Wildlife: Cultural: Land Use: 09ER~LL EVALOAIION! Effects resulting fran changes In water quantity and quality. toss of .resident fisheries habitat. Loss of wll d II fe habitat. ~ significant dlffer- en~e between schemes regarding effects down- stream of Dev II Canyon. Difference In reach between Dev II Can yen dam and tunnel .re- regulat ton dam. Minimal differences between schemes. MJ n I mal dl Herences between schBrles• Inundation of Potential differences archeological sites. between schemes. Inundation of Devil Canyon. Significant dlff~rence between schemes·, With the tunnel scheme con- irolled floWs between regula- Tion dam and downstream power- house of fer5. potent I at for anadromous f I sherfes enhance- ment In this 11 mile reach of the river. Devil Canyon dam would Inundate 27 mlles of the Susttna River and approximately 2 miles of Devil Creek. The toone! scheme would Inundate 16 mlles of the Susltna River. The most sensitive 11lldllfe ha- bitat In this reach Is upstream of the tunnel re-regulatton dam where there Is no significant difference between the schames. The Dev II Canyon dam s:cheme In addition Inundates the river valley between the hlo dam sites resulting In a moderate Increase In 1 mpaets 11> w II d I! te. Due to the larger area Inun- dated the probability of Inun- dating archeological sites Is increased. The Dev II Canyon Is cons I de red a unIque resource, 80 percent of which wou I d be I nun dated by the Dev II Canyon dam scl!eme. This would result In a loss ot uoth an aesthet lc value pi us 'the potential tor llhlte water recreation. lf\'3 .annal scheme nas overall a tower Impact oil Ilia euv It o•unalll• Not a factor In eva! uation of scheme• It fisheries enhancement oppor- tunity can be realized the tun- nel scheme offers a positive mitigation measure not available with the Devil Canyon dam scheme• This opportunity Is considered moderate and favors the tunnel scheme• However, there are no current plans for such enhancement an:i teas lb II- tty Is uncertain• Potential value Is therefore not s I gll- tlcant relative to additional cost of tunnel. Loss of habitat with dam scheme Is less than 5% of total for Susltna main stem. This reach of river Is therefore not considered to be highly significant for resident flsherl es a-nd thus the dl f terence between the schemes Is minor and favors the tunnel scheme. Moderate wildlife populations of noose, b I ac k bear, wease! , fox, wolverine, other smal I mammals and songbirds and some riparian cliff habitat for ravens and raptors, In 11 miles of river, would be toot with the dam scheme. Thus, the difference In toss of wildlife habitat Is considered moderate t~n:i fa110rs the tunnel scheme. Significant archeological si-tes, It Identified, can proba- bly be excavated. Additional costs could range from several hundreds to hundreds of thousands of dollars, but are still consider- ably less than the additional c~t of the t~X~nel scheme. ThIs concern Is not considered a factor In scheme evaluation. The aesthetic and to some extent too recreat tonal losses associ- ated with the development of the Dev II Canyon dam Is -the maIn aspect fa vorl ng the tunnel scheme. How&ver, current recreational uses of Devil Canyon are low due to lim! ted access. Future pass 1 bIll tes include major recreational develop- ment with construction of restau- rants, marinas, efu. lhder suc;h conditions, neither scheme would be more favorable. X X X oc al As ect Potential non-renewable resource dlspl acement Impact on state economy Impact on I oca I economy Selsmfc exposure Overall Evaluation ,.· .. 115 - TABLE B.18 -SOOIA~ EVALUATION OF SUSITNA BASIN DEVELOPMENT SCHEMES/PLANS Parameter Mil I Jon tons Beluga coal over 50 years ] Risk of major structur-al fa t1 ure Potential Impact of fat I ure on human II fe. 80 v I anyon Dam Scheme 110 170 210 A I I proj acts wou I d have sImI I ar Impacts on the state and I oca I economy. AI I projects designed to slmi~~r levels of safety. .4ny dam fa J I ures wou I d ef'fect the same downstream JX"~PU Jatfon. 1. Devil Canyon dam superior to tunnel. 2. Watana/Devll Canyon superior to High Devil Canyon/Vee plan, Remarks Devfl Canyon dam scheme potential hfgher than tunnel scherna. Watana/ Devil Canyon plan higher than High Devil Canyon/ Vee pI an. Essentl~l ly no difference between pl~ns/schames. TABLE 8.19-ENERGY CONTRIBUfiON EVAL~TION OF THE DEVIL CANYON DAM AND TUNNEL SCHEMES Parameter Total Energy Production Capab i I Jty Annual Average Energy GWH Firm Annua~ Energy GWH %Basin P9tential Developed Energy Potential Not Developed GWH Notes: Dam 2850 2590 43 60 Tunnel 2240 2050 32 380 Remarks Devil Canyon dam annually develops 610 GWH and 540 GWH rrore average and f trm energy respectively than the Tunnel scheme. Devi I Canyon schemes develops more of the basln potentia!. As currently envisaged~ the Devil Canyon dam does not deve I op 15 ft gross head batween the Watana s lte and i·he Dev I 1 Canyon reservso Jr. The tunnel scheme Incorporates addl- ttonal friction losses in tunnels. AI so the compen- sation flow released from re-regulation dam 1s not used in conjunction with head between re-regulation dam and Devil Canyon. ( l) Based on annual average energy. Ful I potential based on 1..5BR four dam scheme. • I I I J !ABLE B.20-OVEP~LL EVALUAIION OF 1UNNEL SCHEME AND DEVIL CANYON DAM SCKE~£ 1\TiRIBU1E Econanlc Energy Contribution Environmental Social Overall Evaluation SUPERIOR PLAN Devil Canyon Dam Dev l t Canyon Dam lunnel Dev 11 Canyon Dam (Marg l nat ) Devil Canyon dam scheme t s superior lradeoffs made: Economic advantage of dam scheme ts judged to outwe t gh the reduced environmental Impact associated with the tunnel scheme. = • l Environmental Attribute Ecolo~lcal: I) · I sherI as 2) Wildlife a) !>bose bl Caribou c) Forbearers d) Biros and Bears Cultural; TABLE B.21 -ENVIRONMENTAL EVALUATION OF h'ATANA;DEVIL CANYOI~ AND HIGH DEVIL CANYON/VEE DEVELOPMENT PLANS Plan Com arlson Nb significant difference In effects on downstream anadromous fisheries. HDC/V would Inundate approximately 95 miles of the Susltna River and 28 miles of tributary streams, In- cluding the Tyone River. W/DC would Inundate approximately 84 miles of the Susitna River and 24 miles of tr lbutary streams, Including h'atana Creek. Due to the avoidance of the Tyone River, lesser Inundation of residant flsherfp.s habitat and no significant difference In the effects on anadromous fisheries, the W/DC plan Is judged fu have less Impact. HDC/V would inundate 123 ml les of critical winter river Dt>a to the tower potent! at for direct Impact bottom habitat. on moose populations wtthln the Susttna, the W/00 plan Is judged superior. · WJDC would Inundate 108 miles of this river bottom habitat. HDCJV would Inundate a large area upstream of Vee uti I !zed by three sub-populations of moose that range In the northeast section of the basin. W/DC would Inundate the Watana Creek area utilized by moose. The condition ot this sub-population of moose and the qual fty of the habitat they are using appears to be decrws I ng. · Tha Increased length of river flooded, especially up- stream from the Vee dam site, would result In the HDC/V plan creating a greater potential division of the Nelchlna herd's range. In addition, an Increase In range wou I d be d I recti y Inundated by the Vee res-ervoir. · The area f I ooded by the V<:le reservoIr Is cons I dared Important 1o some key forbearers, particularly red fox. This area Is judged to be .rrare Important than the Watana Creek area that would be Inundated by the W/DC plan. Forest habItat, Important for bIrds and b I ac k bears, exist along the val fey slopes. The loss of this habi- tat would be greater with the W/DC plan. There Is a high potential for discovery of archeologi- cal sltes In the easterly region of the Upper Susltna Basin. The HDC/V plan has a greater potential of affecting these sites. For other reaches of the river the difference between plans Is considered minimal. Due to the potential for a greater Impact on the Nelchlna caribou hard, the HDC/V scheme is considered Inferior. Due 1o the lesser potential for Impact on fur- bearers the W/DC Is judged fu be superior. The HDC/V plan Is judged superior. The W/OC plan Is Judged to have a lower po- tential effect on ar~heologlcal sites. X X X X X X TABLE 8.21 (Continued) With either scheme, the aesthetic quality of both Dev J I Canyon and Vee Canyon wou I d be lmpa Ired. The HDC/V plan would also Inundate Tsusena Fat Is. Due to construction at Vee Dam site and the size of the Vee Reservoir, the J:IDC/V plan would Inherently create access to more wilderness area than would the W/DC plan. Both plans Impact the val ley aesthetics. The difference Is considered minimal. As It 1 s easter 1o ext1and access than to limit It, Inherent access requirements were considered detrimental and the W/DC plan is Judged superior. The ecological sensitivitY of the area. opened by the J:IOC/V pI an re l n- forces this Judgement. OVERALL EVALIY\TION: The W/!:C plan Is Judged to be superior to the HDC/V plan. (The tower Impact on birds and bears associated with HDC/V plan Is considered "f? be outweighed b/ all the other Impacts which favour the W/OC plan.) NOTES; W = Watan!l. Dam OC = Devl J Canyon D<lm HOC =High Devil Car,yon Dam V =Vee Dam Plan JUdged to have the least ~otential im~t X TABLE B.22 -ENERGY CONTRIBUTION EVAL~TION OF THE WATANA/DEVIL CANYON AND HIGH DEVIL CANYON/VEE PLANS Parameter Total Energy Production §pabl I 11j Annual Average Energy GWH Firm Annual Energy GWH % Basin Potential Deve I oped <1 ) Energy Potential Not Developed GWH {2) Notes: -- Watana/ High Devil Dev i I Canyon Canyon/Vee 6070 4910 5520 3870 91 81 60 650 Remarks Watana/Devtl Canyon plan annually devel- ops 1160 GWH and 1650 GWH more average and fhm energy re- pecttvely than the High Devil Canyon/Vee Plan. Watana/Devtt Canyon plan develops more of the bastn potential As currently con- calved, the Watana/- Dev i I Canyon PI an does not develop 15 ft of gross head between the Watana site and the Davit Canyon reservoir. The High Devil Canyon/Vee Plan does not develop 175 tt qross head between ee sfta and High Dev II reservoir. (1) Based on annual average energy. Full potential based on USSR four dam schemes. (2) Includes losses due to unutll ized head. ~ 1 ABLE B. 23 -OVERALL EVALLV\ T I ON Of THE HI Gt DEV l L CANYON/VEE AND WATANA/DEVIL CANYON DAM PLANS ATTRIBUTE Economic Energy Contribution Environmental Soc tal Overall Eva I uation SUPERIOR PLAN Watana/Devll Canyon Watana/Devtl Canyon Watana/Devtl Canyon Watana/Oevtl Canyon (Marginal) Plan with Watana/Oevll Canyon ts superior T radeof fs made: None I l I ' TABLE B.24: COMBINED WATANA AND DEVIL CANYON OPERATION Watana* Dev I i Canyon* Total Average Watana Dam Cost Cost Annua I Energy Crest flevatlon (ft MSL) -·.--- 2240 (2215 reservoir alevatlon) 2190 (2165 reservoir elevat~on) 2140 (2115 reservoir etevatton) Cost ($ X 106) ($ X 106) ($ X 106) 4,076 1, 711 5, 787 3,785 1, 711 5,496 3, 516 1, 711 5,227 Watana Project alone Cprlor to year 2002) Crest Elevation {ft MSL> 2240 2100 2140 Average Annual Energy (GWh) 3~ 542 3,322 3,071 * Estimated costs ln January 1982 dol Iars, based on preltmtnary conceptual designs, Including rei let channel drainage blanKet and 20 percent contlr.genctes. TABLE B.25: PRESENT WORTH OF PRODUCTION COSTS Watana Dam Present Worth Crest Elevation of Producttcon Cos·ts (ft MSL) ($ X 10 2240 (reservoir elevation 2215) 7,123 2190 (reservoir el evatlon 2165) 7,052 2140 (reservoir etevatton 2115) 7, 084 * LTPW tn January 1982 dollars. (GWh) 6,809 6,586 6,264 .. '" ... ) J J I I. TABLE B.26: DESIGN PARAMETERS FOR DEPENDABLE CAPACITY AND ENERGY PRODUCTION (a) Min tmum stream ftow (fi'Onthl y average, cfs) Mean stream flow Maximum stream floW Evaporation Leakage Minimum flow release Flow duration curve Crlticat streamflow for dependable capacity curve (Watana and Oevll Canyon combl nad) Area capacity curve Rule curve Hydraul lc Capacity F l.ow (cfs) 1/2 full best Efficiency 1/2 full best Generator output (KW) t/2 ful I best Ta 11 water ratt ng curves Powerplant capability vs head Watana Dev t I Canyon_ 570 (March, 1950) 664 (March, 1964) 7,990 9,050 42,840 (June, 1964) 47,816 (June, 1964) Approximately cancels prec1pttatlon and \s neglected. Section 4.Hf) Negl tg tb1e Table B.67 Figure 6.69 Negllg ible 1abte 8.68 Figure 8,.69 5,400 ~~h annual potential recurrence treq uency 1 i n 10 years Figure 8.67 Flgure B,.68 Flgure B.62 Figure B.69 l, 775 1,895 3,550 3,790 2,900 3,100 87 87 91 91 94 94 9\,000 82,000 183,000 164,000 156,000 139,000 figure 8.67 Figure B.68 Figure B. 70 Ftgure Be 73 • l .1 1 ' I I I L l TABLE 8.27: WATAW! -MAXIMLM C".APACITY REQUIRED (M'r/) OPT I ON 1 -THERMA.L AS BASE Hydrological Year 1 \ 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 j 20 I 21 22 23 24 25 26 27 28 29 30 31 32 *Restr feted by peak demand **t-1ax i mum va I ue ***Inc I ud I ng Dev i ~ Canyon CAPACITY CMW) 1995 2000 743 762 550 569 760 779 749 768 744 763 763 782 737 756 771 790 799** 818** 5G3 582 769 788 784* 803 773 792 771 790 745 764 550 569 745 764 554 573 771 790 550 569 550 569 !'50 569 784* 803 747 766 550 569 550 569 728 747 550 569 785* 804 550 569 787* 806 754 773 2010*** 838* 680 836* 836* 868* 832* 838* 836** 825* 683* 832* 829* 832* 838* 844* 840* 836* 684* 832* 685* 67& 672 834* 838* 684 678 839* 675 833* 678 837* 839* - ' • 'I • I I I --------. ' . ' . ~ . . ' \ . . \. TABLE B. 28: WATAW!. -MAXIMLM CAPACITY REQJIRED (MWi OPT ION 2 -THERW'.L AS PEAK CAPACITY (MW) -- Hydrological Year 1995 2000 1 575 575 2 382 382 3 592 .592 4 581 581 5 576 576 6 595 595 7 569 569 e 603 603 . 9 631 631 10 395 365 11 601 601 12 616 616 13 605 605 14 603 603 15 577 577 16 382 382 17 577 577 18 386 386 19 603 603 20 382 382 21 382 382 22 382 382 23 616 626 24 579 579 I 25 382 382 26 382 382 27 560 560 28 382 382 29 617 617 30 382 382 31 619 619 32 586 586 *Inc I ud 1 ng De•i II Canyon 2010* 838 389 839 836 868 8.12 f£8 836 825 391 832 829 832 838 844 840 836 392 832 393 386 380 834 838 392 386 839 383 833 387 837 839 - -• J • -I ' . . .... • ""' ... t"'-' • . . . "-. --~ -----. --, .It~, • 1 · 117 • • • i;;:l #' ~ • .. • • :·. . • . -~ . . ... • . . -,' ,.. . b. . . • ~ ~~ ~:: .·~. -:. -h:..~. -, . .-. . . .. . .. . 1 J L L • TABLE B. 29: DESIGN DATA AND DESIGN CRITERIA FOR FINAL REVIEW OF LAYOUTS River Flows Average flow {over 30 years of record): Probable maximum flood (routed): Maximum Inflow with return period of 1:10p000 years: Maximum 1: 10,000-yaar routed discharge: Maximum flood with return period of 1::00 years: Maximum flood with return period of 1:50 years: Reservoir normal maximum operating level: Reservoir minimum operating level: Dam Type: Crest elevation at point of maximum super elevation: Height: Cutoff and foundation treatment: Upstream slope: Downstream slope: Crest w 1 dth: Diversion Cofferdam type: Cutoff and foundation: Upstream cofferdam crest el evatlon: Downstream cofferdam crest elevation: Maximum pool level during construction: Tunnels Final closure: Releases during Impounding: SpIll way Design floods: Main sp r II way -Capacity: -Control stt·ucture; Emergency spt J I way -Capacity: -Type: Power Intake Type: Number of Intakes: Draw-off requirements: Drawdown: 7,860 cfs 326,000 cfs 156,000 cfs 1 i 5,900 cfs 116,000 cfs 87,000 cfs 2215 ft 2030 ft Rockflll 2240 ft 890 fi" <lbove foundation .. Core founded on rock; grout curtain and downstream drains 2. 4H: lV 2H: 1V 50ft Rockft II St urry trench to bedrock 1 :s5 tt 1475 ft 1580 ft Concrete I in ed , Mass c0ncrete plugs 6,000 cfs maximum via bypass to outlet structure Passes PMF, preserving lntagrfty of dam with no foss of lffe Passes routed 1: 1 O, 000-year f I ood wt th no damage 'to structures Routed 1: 1 0,000-year fiood with 5 ft su,·c.harge Gated ogee crests PMF mtnLls 1:10,000 year flood Fuse plug Rat nforced concrete 6 ~1ult!-level corresponding 1o temperature strata 1 85 feet . ' I I j J J J 1 TABLE B. 29: (Cont' d) Penstocks Type: Number of penstocks: Powerhouse Type; Transfonmer area: Control room and administration: Accass -Vehicle: -Personnel : Power Plant Type of turbines: Number and rat l ng: ~ -.. ". Rated net head : Des f gn f I ow: Normal maximum gross head: Type of generator: Rated output: Power factor: Frequency: Transformers: Tailrace Water passages: Surge: Average tailwater elevation {full generation): Concrete-lined tunnels with downstream steel I J ners 6 Underground Separate gallery Surface Rock tunnel Elevator from surface Francis 6 X 170 MW 690ft 3., 500 cfs per unit 745ft Vertical synchronous 190 MVA 0.9 60HZ 13.8-345 kV., 3-phase 2 concrete-lined tunnels Separate surge cham~ers 1458 ft ' I fi· t .. PRELIMINARY REVIEW Technical feaslbtl tty Can pat I b II I ty of I ayout with known geological and topographical site features Ease of constl~uction Physical dimensions of component structures In carte~ In I ocat Ions Obvious cost differences of comparable structures Envtrono9ntal acce~t- ab i I ity Operating characteristics TABLE 8.30: EVALUATION CRITIERA INTERMEDiATE REVIEW Technical feastbil tty Com pat Jb! I I ty of I ayout with known geological and topographical site features Ease of construction Overall cost Envlr~nmenral accept- ab I llty Operating characteristics Impact on construction schedule F l N.I\L REV l EW Technical feasibility Compatibility of layout with known geological and topographical site features Ease of construction Over a I I cost Env itonmental impact Mode of operation of spill- ways Impact on construction schedule Design and operating limTta- tJons for key structures .. \ TABLE B. 31: SUMt>\1\RY OF COfwPARAT I VE COST EST I W\TES INTERMEDIATE REVIEW a= ALTERf\LA.TIKE ARRANGEt4ENTS (January 1982 $ x 10 ) WP1 WP2 WP3 WP4 Diversion 101 .. 4 11~ 6 101.4 103. 1 Service Spll I way 128. 2 208.3 122.. 4 267 .. 2 Emergency Spillway 46.9 46.9 Ta J I race Tunnel 13. 1 13. 1 13. 1 ao Credit for Use of ~~k in Dam (11. 7) (31. 2) (1 a. 8) (72. 4) Total Non-<:ommon Items 231. 0 349.7 26!i 0 30~ 9 COiliiOOn Items 1643. 0 1643.0 1643.0 1643.0 Subtotal 1874. 0 1992.. 7 1908. 0 1948. 9 Camp & Support Costs (16%} 299.8 318.8 305.3 311.8 Subtotal 2173. 8 2311. 5 2213. 3 2260. 7 Cont ~ ngency (20$) 434~ 8 462.3 442.7 452. 1 Subtotal 2608. 6 1773. 8 2656. 0 2712. 8 Eng I near J ng and ( 12. 5$) Adminlstratfon 326. 1 346.7 332.0 339. 1 TOTAL 2934. 7 3120. 5 2988. 0 3051. 9 .. TABLE 8.32: DEVIL CANYON ~ M'\XIMUI~ CAPACITY REQUIRED (MW) Capacity (Mv/) leal Yaar 2010 (0 tJon 1 and 2) 1 544** 2 353 3 546 4 546 5 514 6 548 7 544 8 546 9 557 10 351 11 548 12 551 13 548 I 14 544 15 538 16 542 17 546 18 350 I 19 550 20 349 21 355 22 361 ti 23 548 24 544 25 349 26 355 27 543 0 28 359 29 549 30 355 31 545 ~ 32 543 **Maximum Value ' " .. I l L • " . ,) {.._! -• '"~ •-··-"'-·.-~~-~r-··----•~'"-~··•·_,,....-. ___ ~...._~,__..,_,..,.-~----~~· _,__~---=--~-·~~--,......-..,;.--.[~-· ~. ~~:~-' TABLE 8.33: CESIS~ Q\TI\ AND DESIGN CRITERIA FOR REVIEW OF Al TERNI\T I VE LAYOUTS River Flows Average flow (over 30 years of record): Probable maximum flood: Max. flood with return period of 1:10,000 years: Maximum flood with return period of 1:500 years: Maxim~m flood with return period of 1:50 ysars: Reservoir -~ Normal maximum operating level: Reservoir mlnimum operating level: Area of reservoir at maximum operating level: Reservoir tlve storage: Reservoir full storage: Dam Type: Crest elevation: Crest I ength: Maximum height above foundation: Crest width~ Dl vers Jon Cofferdam types: upstream cofferdam crest elevation: Downstream cofferdam crest elevation: Maximum pool level during construction: Tunnels: Outlet structures: Final closure: Releases during Impounding: Spl llway Deslgn floods: ServIce sp til way -capacity: -control structure: -energy dtsstpatlon: Secondary spIll way -capacity: -control structure: -energy dlssJ pat Jon: Emergency spill way -capac tty: -type: 8, 960 cfs 346,000 cf.li 165,000 cfs (after routing through Watana 42,000 cfs (after routing through Watana 1455 feet 1430 feet 21, 000 a:: res 180,000 acre feet 1,100,000 acre feet Concrete arch 1455 feet 635 feet 20 feet Rockf I II 96Q feet 900 feet 955 feet Concrete I I ned U:>w-1 eve! structure wtth slide closure gate Mass concrete plugs ln line with dam grout curtain 2,000 cfs mln. via fixed-cone valves Passes PMF, preserving Integrity of dam with no loss of I I fe Passes routed 1: 10, ooo-,ear flood with no damage to structures 45,000 cfs Ftxed-cone valves Five lOB-Inch diameter fixed-cone valves 90,000 cfs Gated, ogee crests Stilling basin pmf minus routed 1: 10, ooo-,ear !-food \.. Fuse pi ug TABLE B. 33: \Con"t' d) Power In-take Type: Transformer area: Access I Type of "turbbes: Number and raring: Rated net head: Maximum gross head: Type of generator: Rated output: Fbwer factor: I I l f_ L. [ L l Underground Separate gallery Rock Tunnel Francis 4 x 140 MW 550 feet 565 feet approx. Vertical synchronous 155 MVA Q.9 ~-I, . . . . . . ..,. . . . .. • ' " ,,' ' ' ,, . ··--~-------~------~...._,......,..,~.~~·---·-"""""''"'~--...-.-·--.--~-··--~--~~"~~·~-..... ~--~---··"·-··--·-· .I .I TABLE 8,.34: SUMW\RY OF COWAR.\T I VE COST ESTI M\TES -·- J PRELIM I NA.RY REV 1 E.W OF ALTERNAT 5VE ARRANGEMEt-ITS (January 1982 S X 10 ) I Item DC1 OC2 Dq3 PC4 Land Acquisition 22. 1 22. 1 22. 1 22. 1 Reservoir 1U 5 1 n 5 1 tl. 5 1 a. 5 ~1ain Dam 468. 7 468. 7 468. 7 468.7 • Emergency Spillway 25.2 25.2 25.2 2!i 2 Power Facll lttes 21 to 7 211. 7 211.. 7 211. 7 Switchyard 7.1 "41 7.1 7. 1 M I sc el j an eo us Structures 9.5 9.5 9.5 9.5 • Access Roads & Site Faci I ities 28.4 28.4 28..4 28.4 Common Items -Subtotal •7a:t 2 783; 2 783; 2 l1i3: 2 Diversion 32. 1 32. 1 32. 1 34. 9 l Service Sp I II 't!aY 4(i 8 53. 3 sa. 1 85. 2 Saddle Dam 19 .. 9 18.6 1 6'. 6 19 .. 9 Non-Gommon/lt~~s Subtotal 98: 8 ·-roo lOot 8 14(1 0 Total 882.0 887.2 884.0 923.2 I Camp & Support Costs ( 16%) 141. 1 141. 9 141.4 147.7 Subtotal 10231 1 1 029> l 102$4 10701 9 Contingency (20$) 204 .. 6 205..8 205.1 214.2 I Subtotal 12217 1234 9 1230. 5 128i 1 Eng Tneed!lg & Administration (12. 5%> 153.5 154.3 153.8 160 .. 6 Total 1381 .. 2 13891 2 13"B4;""3" 144 5I 7 l l L L. • .. I I TABLE 8.35: POWER TRANSFER REQUIREMENTS (MW) I INSTALLED CAPAC J TY TRANSFER ~QUIREMENT I Sus itna to Susitna to Year Watana Devi I Canyon Total Susltna Anchorage Fairbanks . 1993 680 -680 578 170 I 1994 1020 -1020 867 255 2002 1020 600 1620 1377 I 405 I I. I TABLE 8 .. 36: SUMMARY OF tiFE CYCLE COSTS I. TRANSMISSION ALTERNATIVE j 'I 2 3 4 5 Transmission Lines 1981 $ X 106 L Capt tal $156.70 $159. 51 $133.96 St 40.94 $159., 27 Land Acquisition 18.73 20.. 79 18.07 20.13 18.65 Capitalized Annual Charges 127.34 130. 14 107.43 112.83 t 26. 91 Capital fzed Line losses 53.01 5~·.50 n4 .. 51 65.82 42.82 L --·- Total Transmission line Cost $355.84 $3~. 94 $323.97 $339.72 $347.65 ' ~wItching Stat tons .. -. •• "" Capital r $114 ... 09 $106.40 $128.32 $120.64 $154.75 Capital I zed Annual Charges 121.02 113.30 135.94 128.22 165.02 -... Total Switching S+atJon Cost 235.11 219.70 254.26 248.86 319.77 ----TOT At-$590 .. 9.5 $584.64 $588.23 $588.58 $667.42 I I I i . ' • ' ¥·~->' ...-.,.,_,__,,_., ,_ __ ._..,.,...,_.. _ __,_ •• ~ >-•""""'-'••C·-'.--.• ~· ~~ -~..-'-·· -"-•• ~ >·•--•~ ••• •-••• Type t. lechn leal -Primary -Secondary 2. Econcmlcal -Primary -Secondary 3. Environmental -Primary -Secondary TABLE 8.37: TECHNICAL, ECON0-1 IC, AND ENVIROf-1.1ENTAL CRITERIA USED IN CORRIDOR SELECTION Criteria General Location Elevation Relief Access River Crossings Elevation Access River Crossings Timbered Ar~s Wetlands Development Existing Transmission Rlght-of..Way Land Status Topography Vege·tatlon Selection Connect with lntertla near Gold Creek, Willow, and Healy. Connect Healy +o Fairbanks. Con- nect WII low to Anchorage. Avoid mountainous areas. Select gentle ret ief. Locate In proximity to existl ng transportation corridors to facilitate maintenance and repairs. Minimize wide crossings. Avoid mountainous areas. locate ln proximl~/ to existing transportation corridors to reduce construction costs. M!nlmlze wide crossings. Minimize such areas to reduce cl~arlng costs. Minimize crossings whlch require speclal designs. Avoid ~lsting or proposed developed areas. Par~ II et. Avoid private lands, wtldlffe refuges, parks. Select gentle relief. Avoid heavily timbered areas. • - TABLE 8,38 Envlroniwentil ln~entory .. Southern Study'Area (Wt11ow to Anchoraqe/Polnt Had~!nzt,e) Corridor 1\pprolt. 1\jlpro•. I Approll. I Topography Sotls I Sepnt length Road Crossings Rlver/Creek ,CrosstngJ _(Httes) Willow {tOO'), cross!S • Willow to near A8 6C' AUf 1\[f rc 38 35 26 27 lZ 2 hwy (Rt. 3, Glenn) 6 111hl duty roads 1 un mproved rotd 2 trath 1 railroad 4 hwy (Glenn, 4x) 3• light duty roads 7 unimproved roads i trail several r~ltro&ds 1 highway {Rt. J) l tractor tra t h 1 hlgh~ay (Parks) l tractor 'iratl 2 tractor tral1s •· l rher 17 creeh 4 rivers 11 creeks 1 rtver 6 creeks 1 rher 6 creeks Z creeks WHlow Cit, follows Deception Cit. (1000'~ along rldgo of latkeetnl ts, t.t. Into P1l~ (200') Pal~~~er (200 1 ),. crosses Knlk River to base at Chugadh Hts. 1500' ), along Knlk mt 200'-300'), to 1\m:horage zoo•) . Willow (100')~ s. along Susttna Rtver plains (flat, wet area, with drier, raised lc~ees, 200'-400'), to F at 150' Willow (100'}, s. aiong flat wt aru (200' -400'), to F at about 150' F at 150' &long flats to C near sea 1eve1 a. Source: United States Depart~nt of Agriculture, Soil Conserv,tlon Ser~fce 1979. See Append hi Table 8-1 for ellplanat lon of sof.1 untts. b. Source: Clftl/l~lmes and Marver. 1980. P•Prlvate, SPTAaState Pateflt~d or Tentatively Approved. SP•State Patented, OAP•Oorough Approved or Patented. Pahner-S04 PI 1~~~er EOl Palmer-EOl t:n tk 1\rlll -Erl S. of Ek1utna to n. or Anchorage -505 Anchor age -504 w 111014-504 S. of WlHow to· to F-SOl Near t. Sus ttna River -505 ReNinder-504 tte~r F -S04 ('Cear C -SOl band Ownership/ b Status A to s. of Willow Ck Rd. crossing-mostly P, with s~ DAP and some SP; ••• to due n. of Wasttl;~alnly SPl~; .•. to 8-MOstly P, with SOMe BAP and SP 8 to ~r1tk R. -i'; , •. to Bfrchwood-•alnly YS ~lth some SPTA, P and 8AP; Btrchwood ar~a-P; s.~. of Birchwood to near c•-u.s. Ar~y Htlltary Wdt; C'-Data void Hear A-P: route fairly even MIK of BAP and SPTA; some P near Fish Cit; area surrounding l Su!ltna R- Su5ttna fltts Game Refuge; near .F-SPTA A, s. to Rainbow l.- mostly P, sma\1 p~rcels BAP; State Selected fed. !'a:·cel w. of Willow L.; ~. tot. Su~ltna R. -Haney lake StatE Rec. Areai to F o Ml~ of SPTA and BAP F tu 1 MI. ,,-SPTA; ••• s. to Horseshoe L.-Pt HacKen~te ~gr. Sale•··· ~. to C- maln1y SPTA, s~ BAP Existing/Proposed Exht lng Oe'lelop!l!nts ~1ts-of-Way Ag. uses,n. & w. of follows no known right- Ptl~r; ag/res. use of-w~y for appreciable near t. SUI ltna; dhtance propos!d c"plhl site; •bed re,. 1rea At WI 11ow Cit.; Wl11~ air strip; cabtn near A Urban uses tn Anch.; rara11els trans. line passes throuGh/near Knlk R. to Anch.; several commU~Itles: parallels Glenn Uwy fron Eagle R, Birchwood knit R. to Birchwood; Eklutna, Chugiak, p~ra\1~\~ ~R-Eagle to Ptters Ct. c• Red Shirt lake-Generally p~rallel~ a ~IKed resfd~ntlal trector lrall use; near residential & recr. areas s.w. of Willow; Susltna flats S\ate Game Refuge Ht~ed res. areas; lakes u~ed to land float planes Scattered resldentlol/r.ablns on llorseshbe lake; proposed 19. uses tn area Ho ftno'lm Generally follows a • tractor lra' I f ..• ! I- r I , l \ Corridor $e9'f'E'Ol AS BC' AEF FC ,__ r - TABLE. 8 .. 38 (CONTtiJ) Environmental Inventory -Southern Study Area (WII1low to J\nchorage/Potnt Mackenrle) Scentc Qual tty/ Recreatton Gooding L. -bird-w3tchlng~ rec. trails e. or w n lmr-hunttny· Mk htg, )(•C skilnl, dug s eddlng, !now- trobll ng, snowshoeing; rec. tratl by Decep. Cx-snow- .ablllng, dog sledding, fIsh lng Passes netr Z ca~tng grounds; parallel~ !dltarod r&ctny trail (xMc· sk t log~ s edd tng, sn~bi 1 lng); bJrdwatchlng at Eklutna Flats 1nd Hatunuska River X-c ski L snowmobile tra\15; re(reatton area s.w. of Will~ Hlled ret. areas; Haney lake State Rec. a!"ea; tn·lls and ~lttple uses; ••Y crc~s Goose B&y St. Game Rduge May cross Sustlna flats State Wildlife Refuge Cultural 1 Resources Data vold Oda ¥~-?td bah vold Yegetat ton b . Up lD,m}, flllxed deciduous- conifer· forests (birch-spruce)~ open and closed l$l0Slly TAll shrub (alder); s~ MOodland black spruce; bogs along Oeceptton Ck • Deciduous 1ore~t (bals~ poplar) along t•her, prob1bly birch/spruce forest~ on uplands In MOSt of area Oata votd lllghe~ grotmds: Spruce .. birch-poplar forests t~et sedge grass bogs and black spruce for~sts prevalent tn lowel" t.IQ\f Upper half; mostly upland birch, spn.ce L aspen lower half: Nel sedge~grass bogs ~nd black spruce; some btrcht spruce; as9en on higher ground Spruce forests, spruce- birth forests~ sedge-grass bogs and black spruce bogs Ftsh c Resources Willow tk. -chinook GllMOn, grayling, burbot, longnose sucker, round whitefish, Dolly Varden, slimy sculp 1tn• hke trout Me rainbow tr;oul. in lakes; t. Sus~tnl R. ~ \\ng salnon; necep. Ck. -k$ng, pink sa\moh Sockeye, ch lnook. iJirlka ch1J111 0 coho sa leoon tn large rivers; grayl lng burh:>'t, longnose sucker, ro!Jnd wh lte· fish, Dolly Varden, sli~ sculptn~ lake and rainbow trout In lakes L stream1 sa.liiOrJ of part icuhr stgnlflcance tn the ~atanuska and Kn ik R t t~P.rs Willow Ck.: chtnoot salmon; lake &nd rainboW trout poslble tn so~ lakes; also, In streams are grayling, burbot, longno;e sucker, round whitefish, .Dolly 'lsrden, s1 h•Y sculpin; Red • Skirt L. -lake trout, sockeye sal~n Lakes ~ay ccntatn rainbow and lake trout; possibly grayling in the reg ton lake ~y contain rainbow and lake trout; poss lbly grayHng tn the region · d Birch Dahl votd Waterfowl and shore: bird nesttng , areas around Kntk An• and Eagle Rher Flats Waterfowl and shore bird nesting in Willow Creek/ Delta Islands Same as AOF Waterfowl and s.hore bird •igratton route, feeding and nesttng area d forbearers Data t>old Data void Data void • d Bfg G~me Except near Palmer- block be~r summfr· range. moose winter/ summer range, ml9rat corr1dors and calvir area; near A also browr\ bear ~unrner range and feeding area Data vutd Brown and black bear feedlns area, moose winter/summer range and cal~fng area Same as ADf furbearer and small Ma11111al stmller/ winter range Black bear summer r~ogc and feeding area; moose wtnter/ summer ranfie, reedtn snd calving area a. Coasttl 1rea probably h1s many sltes,·avatlab1e literature not yet ~evl~wed. ~. Ta;l shrub•aider; low sh~ub•dwarf b\rch, and/or willow; open ~pruce•block (wet) or whlte spruce, 25%-60~ co~en woodland spruceawhtte or black spruce. 1~-25~ d. little data available. Source cr l~for.atlon In this table: Alaska Oepart~nt of Fish and Game l978b. t. little dati available. Source of lnformatton In thts table: 1\lasita DepArtMent of Fish and Game l97Ba. cover, ~••ed forest• spruce-birch. .. J TABLE B.,?f) Enviro~nu1 Inventory -C!titral Study Aru (Oasa Sites to Intert ie) Corr'tdor Appro;r.. .Approx. f Approx. I Toe>ogra.phy Soi1s 1 Sc:gn'Jent A8 C13 SEC JC' Cf' AG A."i Ht HJ l.engtn nottd t.ross ings Rfver/Creek. !~iles} ~o,ssil'l2i 7 0 5 creeks 18 0 15 1+ 1 river 4 creek; 23 0 8 creeks 18 0 11 cr~ks a 0 1 CT'~ 1.5 0 2 creeks 65 0 1 river 35 cre-eks 22 0 9 eree~s 21 0 15 creeks 2~ 0 13 creeks Hoderite sicping i. r1~ of Suslt"a R. Vall~y; crosses dee) rav1ne at Fag Ct. at about zooo· contour zooo• e.ol'<tO~ Along S.. ri• of Susitna River; cross~s 3 steep ;orges ~&hly sloping terrain; crasses Susitna R. ne1r Gold Creek {800') CMsses ~c!erat.e slopes around Stephan 1. ake; w. , t.~en n. to ~void d~ep·r~vioe at Ch~ako Ck., th~:. fo nows s. rta of Susitna at about 2000' A {about 2000') to 3500'; cro~ses d~p ravine at Devil Ck. (2000'); gce5 by several ponds .; {2000' ). $.w. through gently sloping High Lake area,to C ~ 01!:-tn Canyon ( 2000~) Peti1 c~nyon (<2000') ~est ~s· 60!'.)1 deep Portage C~ gorge; w. across gt1tt le. terra:'ln to f (1200') A {2000' )., n. 'long Oeadtaan Ck. to 3200'; ~rosses SnJsn~ana drainage !at 3200 •) ~ orops to Henan a River {2400' j and hirly flit terrain tuG {2200') A (ZOOG'), along T!.u:iena Ck-~; p~~t Tsusen~ Butte; through J:t.. pass at JGOO• H (3400') thrcugh 1;1ts.; along J.u:k R. dra ina~ and Caribou Pass; to I at 400' H (3-WO') throu91 •u~ along Por-tage Ck. draina~. through pass at 3600'; into Devil Crw drainage; to J at 2000' SOlS B westward· S015; near C·-SOlO OSlO B, westward ~ OSlS; bet~1 a' c- IU3; near C • SOlO A, \t'l!:latward ... OSlS; rE!'I'IIainder, except _J - 0516; near J • SOlO OSlO SOlO Near A and along Denali Hwy • OSU; through mt~.-SOl6 Near A .. SOlS; rnt. baS.! -S016; mts. -RHl ms .... RMl; a 1 ong hwy • SOlS Near J ... S016; mid elevation-. ... SOl7; IItts • • RHl. •· Source: United St&\tes Oepartme.,t of Agricu1ture, Soil Conservation S·r:rvice 1979. S~ AppendiX Table B•l for explanaticn of $011 units~ b., Source: CIR.l/Holmes and :tarver. 1~80. P•Private, SPTA•State Patented (lr Tentatively .Apprond, SS•State S,elet:.tion, \'S•Village Selection. Land Ownership/ Statusb vs vs C to l 1/2 m i . e. cf Susitna R. - VS; Susitna R. tc 1 1/Z mi. e. - SPTA; •n to O·P vs except where corridor skir-ts Cheeeha.lco Ck. ravine, .tlir.h is classified. SS Suspended SS except at J ar at A westward across rsusena Ck •• which are V! SS '"gept at J a.r C which ar~ \'S C to 1 l/2 ~ai. e of Miami L. mainl . VS with SliiA 11 parcel of SS; .... to F-P A -YS; n. of A t s.w. of Big L. - SS; ••• to s .. of Deadman. L. -SPT.' .... to Oen,,l1 Hw.> • Fed. D-1 L&l'\d; da.ta void fgr 8 mi.; around t;- Small :ed. Par~e . A • VS; ·~· to n. nt Tsusena Butte SS; data void beyond here I -VS; data voic to east .l -VS; Devil Ck drain&Jgt .. S.); dat1 void beyond he,-, . ~ 1 Corridor S~ts AB 8C CD SEC AJ JC CF AH HI HJ . ' * c~ ,. ·-~·-·---·------,.,_,,_._ ..... ~ .......... , ... _. ___ ~.-..ro-~----~·--..._......,,,.~--"·'"~""'-.....-~-___________ ,_.,~ .. ---·-- TABLE B.39 (CONT 1 D) Environmental Inventory -Central Study Ar~a (0~ Sites to !ntertie) Fish 1 Resources Fog Lakes -Do11y Varden, sculpin; Stephan Lake cont1fns lake and rainbow trout, sockeye & coho salmon, whit!fish, lon;nose sucker, grayling; btirbot Several ~all tributaries crossed, perhaps used by grayling Same as SC Several ~11 tributaries crossed, perhaps used by grayling, burbot Dolly Varden; grayling in Tsusen: Creek Surbot; no data for High Lake Portage Creek has king, chinook, ch~ and pink salmon, grayling, burhot Dolly Varden; lakes -1~~ trout, grayling, white-fish; tributaries to Nenana Rfver ano Brush~ana Cre~ n. of Deadman Mt, and Jack R. near Denali Hwy considered important fish habitat Dolly Varden; grayling Lake trout, Caribou Pass ar~a; Jack River s. of Caribou P!SS considered important fish habitat; data void Portage Creek o king. chinooK, chUM, and pink salmon, grayli~g. burbo~ Birds Potential raptor nesting habitat in Fog Creek aru Potential raptor nesting habitat along Devil Canyon Potential raptor nest.ing habitat along Devil Canyon Potential raptor nesting habitat along Devil Canyon and 1long drainages upstre!IRI; Stephan Lake area important to waterfowl and migrating swans Data void Potential raptor hab. by Devil Canyon; golden eagle nest along Devil Ck. s. of confluence of ck,. from High Lake Potential raptor · habitat along lower Portage Ck. and frOQ Port .age Ck. mouth through Devil Canyon Waterfowl numerous at Oudriian Lake; impor .. t&nt bald eagle habitat by Denali Hwy and Henana R. just w. of Monahan Flat; unchecked bald eagle nest along Deadman Ck, s.e. of Tsusena Butte Known active bald eagle nest s.e. of Tsusena Butte Data void · Oata void Furbearers Excellent fox and marten hab iht; Fog lakes support numerous beavers and muskrat; otters corrmon Exee 11 ent fox and marten hAbitat Area around Devil Canyon has excellent fox And JDarten habit at Excellent fox and marten habitat, particularly around St~han Lake Red fox denning sites, nunerous. beaver, IIIUSkrat and mink, especially around High Lake ~ '.me as AJ Area between Parks Hwy and Oevi 1 Canyon su~~~rts numerous teaver, ~~skrat, and mink Population relatively low, although beaver~ min~. fox present; Deadma.'l Ht~ to Denali Hwy •• moderate pop. red fox PoDulat1on along Tsusena Ck. pro- bably relatively 1o~; with beaver, mink, and fox probably present Data 't"'id Numerous beaver, muskrat, and mink around High L~e a. Lfttle data available, s~urces of information tn thfs table; Alaska Department of Fish and Game l978a, Friese 1975, and Morro~ !980. Supports large pop. of moose; wolves, ~lverine and bear, (especially brown) c.onmon; caribou regularly use area ·Area ~round Stephan L!k~ & Prafrie Ck. supports 1 arge pop. of 11100se; wo 1 ves * wolverines, and some bear (especially brown) corrmon; caribou regular users Moose, caribou, and bear habitat Same as AB )buth of Tsusena Ck. ili'Jj)ortant moose habitat; heavily used by black and brown bear Important moose and bear habitat; data void Probably ill1)ortant li!QOSe winter;ng area and black bear habitat; at least one wolf pack Probably important area for caribou. · expec:ia lly in the north Data void O.tta void Data void I j J I I I I I I l l r L TABLE 8.39 (CONT'D) Environrnent!l Inventory • Central Study Area (Dam Sites to Intert1e) Corridor Segment Existing/Proposed Deve1ooments AS Fo1 lows general route of proposed Sus1tna access rds.; cabins on Fog Lakes; p14nes use lakes Existing Rights-<lf-Way No known BC Follows general No known rout! of Susitn~ proposed access rds.; c-abins and lodge 0., Stephan L. co Follows propos~d Old Corps trail, s~sitna aeces~ rd.• Gold Ck. to Devil Devil Canyon to Susitna R.; scattered cabins in Cattyon/Go1t5 Carlyon Creek area SEC Follows general route Mo known proposed Susitn& access rd.; cabins and lodge on Stephan Lake AJ Follows a proposed Mo known Susitna access rd. from Watana westw~rd for approx. S mi • ; lodge at High Lake JC G~nerally follows No known propoud Susitna access rd.; lodge at High L3kt Follows i proposed CF Susitna access rd. No known for about 3 mi. fr~ Devil Canyon to . Portage Ck. ; mining, cabins Follows a proposed Parallels Denali Susftna acc~ss rd. • Hwy beyond Watana to just n. of Srushkar~a Ck. Deadman Mt.; drainage to G occasional ctbins; landing strip along Oen&11 Hwy; airport near G Cabins near Tsusena No known Butte HI Cabins near Summit No known HJ Susitna access rd. "o known along Devil Ck. for about 4 mi.; cabins along Devil Ck. drainage Scl!11ic Quality/ R!Cre&tion • og Lakes -:t1gh a ~thet i~ qua11ty; f 'shing in Fog l.llta St~an Lake .. h1gh aesthetic quality Scenfc are4; possible fishing Stephan Lake -high aesthet1: quality; major recreation area for fishing/boating/ planes Hign Lake and other lakes -high aestnetic quality; fishing/ hunting·in High Laxe are• Same as AJ Boating in Susitna; hunting, fishing, hikil'lg '-.... .. Remote flat areas • high vfsibflity; Deadman L. and Mt •• Aleska Range -high aesthetic quality; fishing. fluat pl~nes; major rec. areas by Brushkana and Nenana R •• Orasher L. Tsusena Butte .. aesthetic:: qu&~ity; ~or sheep hunting Area Major sheep hunting are!; bird watching at S1.m11it !. • Scenic drainage; Sheep hunt~ng 1n n. Cultural Resources Arch. site» identified near Watana Dam site and w. shore of Sttph&n Lake; potent~Al for more sites ar~und Fog La.kes and Stephan Like Arch. sites near Stephan LAke Hist. sites \'lear Sold Ck.; data void See AB Arch. sites at Port~ge Oc. and Susitna R. con- fluence and rttar Watan& Da~~~ site No knOW! arch. sith Arch. sites at Porta~ Ck.; hist. sites near Canyon Arch. sites along Deadman Ck. Arch. site n, of Tsusena Butte along Tsusena Ck; data void. Oa.U void Dati void a. Tall shrub•alder; 1~ shru!>•dwarf bfrch, and/Qr wfllow; open spruce•blac!l: (wet) or wh.ite .spruce, 25%-60~ cover; wocd1and spr.uce""--hit~ or black spruce. 1~-25~ cover. mixed forest• spruce-birch. I a Vegetation Mostly woodland black spruce (wet); soMe low shrub Open and woodland spruce forests. low shrub, ooen and c1os~ ~ahed i.)rest in about eqva1 M!Ounts Mostly clos~ mixed forests Woodlanr. spruce and bogs around Stephan Lake; law . shrub. mat & cushion and sedge-grass tundrl at upoer end of Cheechako Ck. drain-age; tall shrub (alder) and mixed forest along Cheechako Ck. and towards Devil Canyon Mostly low shrub. mat & cushion. sedge-gras5 tundra some t&ll shrub (alder) Tall shrub (alder). low shrub and open mixed forest Open & ~lased mixtd forest, tall shrub, low ~hrub. Mostly 11;),; shrub in southern end; northern end -dat~ void Low shrub, tall shrub, woodland spruce Data void ~~ ''\. Mat & c~~~hion, sedge- grass tundra, tall shrub a~d open mixed forest in southern end . ' .ABLE t-~e-..v £nvlronmP.nt.l1 Inventory -~rthern Study Area (Uea1y to hlr\lanks) Corridor ~prox. 1\pprox. f Apprux. I Topography Se!JIIIf!nl Aa BC BOC EOC length {Hiles} 40 50 4G 65 50 40 Road Crossings 2 highway (Park) l trails (1 wtnter) 2 unl~roved rds, 1 nllroad Parks lllghw"y 1 wtnter trail 1 winter trail 1 hwy. (Parb) 1 trail 7 trans Several roads in fairbanks, depend tng upon exact route; 3 trails ,. River/Creek Crossings 3 rivers 15 creeks 1 river 25 creeks 2 rivers 29 creek 1 river 1 SO creeks 2 rivers 22 creeks 2 rivers 10 creeks Salchaket Slough Fo Hoiofs Nenan~t RIver north at 1000' to Browne-crosses Riveq n.w. to Clear flt~S at 500' Clear MEWS (500') north across p~atn (400'). n.e. across Tanana itlver Valley to Ester (£00°) Clear HEWS {500'), n.e. across plain to 1 point about 24 •'· due s. of Ester; n. ~ross plaAn to Tanana R. (400') and n. to . Ester Up ltealy Ck. to pass at 4500'; down Wood R. drainage to Japan Hills (1100'); steep lilts.; valleys Japat~ HHh (1100') n.w. oo ph In· aiong Wood R.; thr~~gh Wood R. Buttes area, n. across lanana R.;·n.to Ester · ,J;spanHHh (lUX>') n. .~ross plain to Tanana R, ( 5(JIO'}: n. to Fairbanks a. An•.J~~es co.-rldor Is louted on n. sIde of l!ea ly Ck. for nn~t of Its length, n. side of Codr Clc., arid n.w. side of Uood R. b~ Source: Unete11 Stales Oeparl~neflt of Agriculture, Sol 1 Conservat ton Servke 1979. See ~~ndb Table o~t for exphn.atlon or soil units .• Sot 1s b I RIO Near 0 -lRlOi flats s. of Tanana Rtver- IQ2; Tana~a Rlver- lQJ; Tanana R. to Ester~IR14 Near B -IRlO Rer~~atnder -IQ2 Hear A. -IRlO; ~t. base -JQ25; Mt. area -RHl; near E -UU Near E -IRl; between E and open flats -lRlO; open flats IQZi Tanana R. -JQJ; Ester -IR14 Hear E -IRl; s. section of flats- IRlO; flats -IQ2; Fairbanks -IQl l~nd Ownership/ Status c .A to e. of Dry Ck.-sma11 Fed. Parcel: ••• to$, of Clear fOIS and at B~tltOSt ly SPTA, s~all parcels of P, SMall Fed. Mat. A.lot. along · Nenana R.; Clear HEWS area-pareel CIRI ·~lectton. and U.S. ArMy Udl. land 0 to 1 1/Z Ml n. -SPTA; ••• to s. to Tanana R. -SS; ••• to Tanana R.-P: ••• to crossing l. Goldslre~ Ck. -~ostly SPTA; ••• to Bonanza Ck. Crossing -SS; ••• to near C-SP; remainder -data void 8 area -SPTA; Fish Ck to Tanana R. -data votd; remainder -SPTA, BAP wtth P at C and just n. of Tanana R • A tQNenana R.-smail Fed. Parcel; ••• to e. of Gold Run -SPrA ••• remainder- data voht s~ as DOC north of the Tanana River Data void Exlstlnq/rroposed Oeve loJ?II!!!nts Scattered residential and other u:;es along Parks ffwy; cabin near Browne; atr strip at etealy Scattered res ldentlal &nd other uses along Parks ttwy; cabin at Tanan~ R. crossing H. Wainwright HH. Reservatton Air strips -Healy and Crtpple/ltea1y Ck s. con f1 uence; cabins-Cody Ck/ Wood R • , Snow Ht • Gulch hlsttog R lghts-of -Way Generally parallc Parks Hwy, RR and tr.:m:;. line-!lc.tl to Browne Follows w/ln se~et ~~. Parks Hwy, RR, at;d trans. line; ~re closely foll( r'ark!> llwy. and tn line and sled rd. of lanana R • No known Parallels s~all r• near flea 1y to Co a Ck.; sma 11 RR -Ill to Suntrana; tral lit pass between llf and Cody Ch. Ft. Ualnwrlght Hll. Ho known Res.; Wood R. Butte VJ\BH rt. Wainwright Hl1. Res.; cabl~ -Wood n. cro~slng s •. of Clear Butte Parallels 8onnlflr lrat1-C1ear Ck. 0 to Fairbanks; trar line just s. or Fairbanks c. Source: CiRI/IIolenes ·and Harver. 1980. P•Prlvate, SPTA•State Patented or Tentatively Approved; SP•State Patened, SS*Slate Selection, BAP•Borough Approved or Patented. i r !~ ! • • Currldor Segnl(!nt AB BC BDC EOC EF L Scenic Quality/ Recreation L rt~rks Jlwy-scenfc area; rafting, kayaklng on Nenana ll. P~rks ttwy -scent~ area; hunt fng, f fsh lng Nf~ open flat-high ··~ lblllty; sno~bllfog In f1~ts s. of f& lrh~nks Scenic quality data vofd; Healy Ck • rafting art~t Cultural Resoun;:es Orr Ck. arch. sl e near Healy; qood posst~lllty for Dlt1er s ltes; date votd Good possibility for arch. sites; dah wtd Good ~ssfblltty for arch. s ftes; dah wid Dry tk. arch. s lte near flealy; few .wch. sites In mountains; Maybe near Japan Hills; data void Wide oren fhts -hfgh Ulgh posslblltty vlslbl1ty; snowmobiling for arch. sites: In flats s. of Fairbank~ data void Wide open rtats -htgh vIs IIJI 11ty Arch. sites have it'!::., ldent If led for tht! Ft. Wainwright and Blair lal:es areas t TABLE 8.40 (CONT'D) Envfronmer;ta1 Inventory -Northern Study 1\r~a (lleah· to Fairbanks) a Vegehtlon Southerr; rnd -dtd Y\J ld Northun ~net -low shrub, sed~-~ras5 tundra S. of Tanan.J Rive•· -wet old rfver floodplain, low shrub an~ sedge-grass bogs; Tanana R. ct·oss lng- wlli6W and alder shrub types, white spruce, balsa. popl~r for!sts aiong river: n. of T&nar.a R. -open and closed deciduous (birch and cspen) forests on slopes, w/woodland sprute and bogs, low shrube and wet sedge-gra~s on ~alley hr•tloms Probably wet, low s~rvb, bogs, wet sedge-grass, alder shrub, lowland spruce; n. of Tanana- upland dectduous forests Data void Probably shtllir ·to bDC ProbJbly SIMilar to EOC; Wl!t. ffsh b Resources c Birds Grayttng, burbot, longnose sucker, ln~ortant golden Dolly Varden, round whl~efish, slt~J eagle kabttat sculpin n~ar ;' Grayling, burbot, 1ongnose sucker, Dolly Varden, round whitefish, s1tmy sculp. fnt salmon (coho, king, chUMJ, sheeff~h: 1a~e chub pos,lble Same as AB S~ as AB, lake ~hub po!slble • Selll1! as ac wfth the e11cept ton of coho sal~n, which I! not recorded . Prime peregrine habtt~t at Tanana R.; prime water- fowl hablht along Tanana R. s. of eorrfdor Hear Totatlanlka Ck. to Tanana R. -prl~ waterfo~l habitat; ~ear Wood R. - t~ortant raptor habitat; between D & C by Tanana R. - ur1me peregrine h>1b It at Important golden eagle habitat 1t A & along tlealy Ck. s. Qf Uslbell I Pk; prfme peregrine habitat on Keevy Pk. rrom Wood R. Outtct to n. of Tanana R.-pr!~~ waterfowl habitat; between 0 & C along the Tanana ft.-prime peregrine habitat. H. of Blair lake Air Force Rang¥. to the Tanana R: :.. prt~~e · w~terfowl hahltat; ~. of Fairbanks along Tanana R.-prt~ bald eag1P. habitat c: furbearers PriMe hebltat -15 MI. frOM Nenana to 0 Prtme hab lht - frCI!I C leir HEWS across the Tanana Prime ~ab It et from 8 to ~truss Tanana River .. Prime hAbitat rr~ E .to the s. abotst 15 .... Prime habftat fro" £ to just n. of Tanlinl River Prime habitat fr~ [ to Tanana Rl¥er c __ Big Game Fro"' Henana R. to B- pr IIIIP. ii'IOOSe and lqJorlllnl hhr:k bear habitat; trom n north- ward ~out to ~•.­ prime ~~e habltftt Clur ~f.WS to 11cross Tanar111 R -prime moose and 1mportanl black bear h~blht; n. of Bonanzll Ck. Exp. Forest -prl~ black be11r habitat 8 to across T an11na R -prime ~ose. i~orhnt black bear hab Hat; Wwd R • to just s. of the Tanana R.-prime black bear habitat Uslbe11t to Japan Ullls- prtme moose ~ caribou habitat; between A & Hystlc Ht.-prl~ sheep hcblt4l; E to the ~. - f~ort. black bear hab. E to just n. of T1nana R.-priMe ~os~. Important black bear h11btht; Wood R. to just • 5. of Tan~na R.-prime black bear habitat • E lc Tanana R.-vrlme moose and l~ortant black bear h~bltat; Cle1r MENS to Tanana R. -prime black be1r habitat 41. h1t shrub•alder; low shrub•dwarr btrch-. and/or wtllow; open spruce:obbct (wet) or white spruce, 25S-60S cover; woodland spruce•whlte or black spruce, !~·25~ cover. Mixed forest• spruce-birch. b. little d1ta co'~•ll•b1e. Sources of lnfor1111llon In thfs table: Alaska Dt1JartllteP~ af :; Ish 1111d G~ 1918& and Morrow 1900. c. Source: YaoBallenberghe personal tot~mmlut lon. Prime habltat'"llllniiiiU!It amoun~ of land necessary to provtde sustained yield for that specie$; ba~ed upon knowledge or lh1l ~pedes' needs fr0111 experhmce of AOF&G fler~onnel. l~ortanl habllal•land 111hlch the AOf&G considers not as crtttcal to a 5pec;es as 11 PriMe habitat but Is valuable. l j J J J j TABLE 8.41 SOIL ASSOCIATIONS WITHIN THE PROPOSED TRANSMISSION CORRIDORS - GENERAL DESCRIPTION, OFFROAD TRAFFICt~.BILITY LIMITATIONS (ORTL}, AND COMMON CROP SUITABILITY (CCS}a EFl -Typic Gyofluvents -Typic Cryaquepts, loamy, nearly level -Dominant soils of this association consist of well-drained, stratified, waterlaid sediment of variable thickness over a substratum of gravel, sand, and cobblestones. Water table is high in other soils, including the scattered muskegs. ORTL: Slight -Severe (wet; subject to flood- ing); CCS: Good-Poor (low soil temperature throughout growing season)e EOl -Typic Cryorthents, loamy, nearly level to rolling -This association occupies broad terraces and moraines; most of the bed~ rock is under thick deposits of very gravelly and sandy glacial drift, capped with loess blown from barren areas of nearby floodplains. Well- drained, these soils are the most highly developed agricultural lands in Alaska. ORTL: Slight; CCS: Good -Poor. IQ2 -Histic Pergelic Cryaquepts -loamy, nearly 1eve1 to rolling The dominant soils in this association are poorly drained, developed in silty material of variable thickness over very gravelly glacial drift. Most soils have a shallow permafrost table, but in some of the very gravelly, well-drained soils, permafrost is deep or absent. ORTL: Severe -Wet; CCS: Poor J IQ3 -Histic Pergelic Cryaquepts -Typic Cryofluvents, loamy, nearly level J J . I J dl • -Soils of this association located in low areas and meander scars of floodp1ains are poorly drained silt loam or sandy loa:; these are usually saturated above a shallow perrnarfrost table. Soils on the natural levees along existing and former channels are well-drained, stratified silt loam and fine sand; permafrost may occur. ORTL: Severe (wet); CCS: Unsuit- able (low temperature during growing season; wet) -Good (but subject to flooding) • IQ25 -Pcrgelic Cryaquepts -Pergelic Cryochrepts, very gravelly, hilly to steep -Soils of this association occupying bruad ridgetops, hillsides, and a. Source: U.S. Department of Agriculture, Soil Conservation Service 1979. See Appendix Table 8.2 for definitions for Offroad Trafficability ~ .. limitations and Corr.mo'l Crop Suitability. • • I I I . ' . I I I TABLE 8.41 (Cont'd) valley bottoms at high elevation are poorly drained, consisting of a few inches of organic matter, a thin layer· of silt loam, under which is very gravelly silt loam; permafrost tab1e is at a depth greater than 2 feet. In locations of hills and ridges above tree line these soils are well- drained. ORTL: Severe (wet, steep slopes); CCS: Unsuitable (wet; low soil temperature; short, frost-free period). IRl -Typic Cryochrf!pts, loamy, nearly level to rolling -On terraces and outwash plains, these soils are well-drained, having a thin mat of cour£0 organic matter over gray silt loam. In slight depres- sions and former d1 ~inage ways, these are moderately well-drained soils, having a thin organic mat over silt loam, with a sand or gravelly sub- stratum. ORTL: Slight-Moderate; CCS: Good. IRlO-Typic Cryochrepts, very graveily, nearly level to rolling-Aerie Crya- quepts~ loamy, nearly level to rolling -Generally we11-to moderately well-drained soils of terraces, outwash plains, and low moraines. Typically, these soils have a silt loam upper layer over gravelly soils. P0ckets of poorly drained soils with a shal- low permafrost table occupy irregular depressions. ORTL: Moderate - Severe (wet); CCS: Good -Poor (wet; low soil temperature throughout growing season; short, ftost-free period}. IR14-Alfie Cryochrepts~ loamy, hilly to steep-Histic Pergelic Cryaquepts, loamy, nearly level to rolling On mid-slopes, these soils are well drained, of micaceous loess ranginn to many feet thick over shattered bedrock of mica schist. Bottomland areas are poorly drained with a relatively thick surface of peatmoss. these soils, permafrost ranges from 5-30 inches in depth. ORTL: Moder~te-Severe (steep slope; wet); CCS: Poor (steep slopes; highly susceptible to erosion). IU3 -Pergelic Cryumbrepts, very gravelly, hilly to steep -rough mo~ntainous 1 and In -On high alpine slopes and ridges close to mountain peaks, these soils have a thin surface mat of or~anic material beneath which is an 8 to 12- inch-thick, dark brown horizon formed in very gravelly or stony loam. This association also includes areas of bare rock and stony rubble on mountain peaks. ORTL: Severe (short, frost-free period) -Very Severe (steep slope); CCS: Unsuitable {short, frost-free period; shallow bedrock). RMl -Rough Mountainous Land -Rough, mbuntainous land composed of stesp, rocky slopes; icefields; and • • ' I I I I I I I I TABLE B.41 (Cont'd) glaciers. Soils on lower slopes are stony and shallow over bedrock. Un- suitable for agriculture. Roads feasible only in major valleys. SOl -Typic Cryorthods, loamy, nearly level to rolling -SptHtgnic Borofibrists, nearly level -Low hills, terraces, and outwash plains have well-drained soils formed in silty loess or ash, over gravelly glacial till. Depressions have poorly drained, fibrous organic soils. ORTL: Slight -Very Severe; CCS: Good (on well-drained soils) -Unsuitable (wet organic soil). S04 -Typic Cryorthods, very gravelly, nearly level to rolling -Sphagnic Borofibrists, nearly level -Soils of nearly level to unduldting outwash plains are well-drained to excessively well-drained, formed in a mantel of silty loess over very gravelly glacia'l till. Soils of the association located in depressions are very poorly drained, organic soils. ORTL: Slight -Very Severe; CCS: Good-Unsuitable (wet, organic). SOS -Typic Cr'yorthods, very gravelly, hilly to steep -Sphagnic Borofibrists, nearly ~evel -On the hills and plains, these soils, formed in a thin metal of silty loess over very grayelly and stony glacial drift, are well drained and strongly acid. In muskegs, most of these soils consist of fibrous peat. ORTL: Severe (steep slope); CCS: Unsuitable (steep slopes; stones and boulders; short, frost-free season). SOlO -Humic Cryorthods, very gravelly, hilly to steep /f. v -Generally, these are well-drained soils of foothills and deep mountain valley.:;, formed in very gravelly drift with a thin mantel of silty loess or mixture of loess and volcanic ash. These soils are characteristically free of permafrost except in the highest elevation. ORTL: Severe (steep slope); CCS: P-oor-Unsuitable (low soil temperature throughout growing season; steep slopes). SOlS -Pergelic Cryorthods -Histic Pergelic Cryaquepts, very gravelly~ nearly level to rolling On low moraine hills, these soils are well drained, formed in 10 to 20 inches of loamy material over very g~"avelly glacial drifts. On foot slopes and valleys, these soils tend to be poorly drain~d, with shallow permafrost table. ORTL: Slight -Severe (wet); CCS: Unsuitable (short, frost-free period; wet; stones and boulders). . . I --,•·-r -··•~"'••--~"-""~"'~··•.....--·~•-~•·•~·~•·~--'~·-~-,_.,....-~-.,._~,,-<' >"•-~---•·••-· "*"'"".._._,._.~._••••·•-• _..,,_., _ _, __ ''"' TABLE 8.41 (Cont•d) S016 -Pergelic Cryorthods very gravelly, hilly to steep-Histic Pergelic Cryaquepts, loamy, nearly level * On hilly moraines these soils are well-drained; beneath a thin surface of partially decomposed organic matter, the soils have spodic horizons developed in shallow silt loam over very gravelly or sandy loam. In valleys and long foot slopes, these are poorly drained soils, with a thick, peaty layer over a frost-churned loam or silt loam. Here, depth of permafrost is usually less than 20 inches below surface mat. ORTL: Severe (steep slope; wet); CCS: Unsuitable (short, frost-free period) - Poor (wet; low soil temperature). . .. ' ~~-- l I I I I I • :./ ~ ·-· -··· ____ ..,_ ........ _.,_,... __ , ___ , ____ ,___ ..__ ... -·--~-----.......... ~~------...;~-------.-------~-~··· TABLE B.42 DEFINITIONS FOR OFFROAD TRAFFICABILITY LIMITATIONS AND COMMON CROP SUITABILITY OF SOIL ASSOCIATIONSa OFFROAD TRAFFICABILITY LIMITATIONS {ORTL) Offro.ad Trafficability refers to cross-country movement of conventional wheeled· and tracked vehicles! including construction equipment. Soil limitations for Offroad Trafficability (based on features of undisturbed soils) were rated Slight, Moderate, Severe, and Very Severe on th~ following bases: -Slight Soil limitations, if any, do not restrict the movement of cross-country vehicles. -Moderate Soil limitations need to be recognized but can generally be overcome with careful route planning. Some special equipment may be required. -Severe Soil limitations are difficult to overcome, and special equipment and careful route ~lanning are required. These soils should be avoided if possible. -Very Severe Soil limitations are generally too difficult to overcome. Generally, these soils are unsuitable for conventional offroad vehicles. Common Cropb Suitability (CCS) Soils were rated as Unsuitable, Good, Fair, and Poor for the production of com- mon crops on the following bases: -Unsuitable Soil or c11mate limitations are generally too severe to be overcome. None of the common crops can be grown successfully in mo5t years, or there is danger of excessive damage to soils by erosion if cultivation is attempted. a. Source: U.S. Department of Agriculture, Soil Conservation Service 1979. b. T~e principal crops grown in Alaska--barley, oats, grasses for hay anJ s1lage, and potatoes--were considered in preparing ratings. Although only these crops were used, it is assumed that the ratings are also valid for vegetables .and other crops suited to Alaskan soils. '----~ -~---~----· --·-----f~--''---·-··"-·---- ] J I I I I I TABLE BA42 (Cont'd) -Good Soil or climate limitations, if any, are easily overcome, and all of the com- mon Alaskan crops can be grown under ordinary management practices. On soils of this group -- (a) Loamy texture extends to a depth of at least 18 inches (45 em). {b) Crop growth is not impeded by excessive soil moisture during the growing seasons. {c) Damage by flooding occurs no more frequently than 1 year in 10. (d) Slopes are dominantly less than 7 percent. (e) Periods of soil moisture deficiency are rare, or irrigation is econom- i c a 11 y f e as i b 1 e .. (f) Damage to crops as a result of early frost can be expected no more fre- quently than 2 years in 10. (g) The hazard of wind erosion is estimated to be slight. -Fair Soils or climate limitations need to be recognized but can be overcome. Com- mon crops can be grown, but careful management and special practices may be required. On soils of this group -- {a) Loamy texture extends to a depth of at 1 east 10 inches ( 25 em). (b) Periods of excessive soil moisture, whieh ca~ impede crop growth during the growing season, do not exceed a total of 2 weeks. (c) Damage by flooding occurs no more frequently than 2 years in 10. {d) Slopes are dominantly less than 12 percent. (e) Periods of soil moisture deficiency are infrequent. (f) Damage to crops as a result of early frost can be expected no more fre- quently than 3 years in 10. (g) There is no more than a moderate hazard of wind erosion. -Poor .. '·· Soils or climate limitations are difficult to overccme and are severe enough • C.! I I I I I I l TABLE B.42 (Cont'd) to make the use questionable~ The choice of crops is narrow, and special treatment or managment practices are required. In some places, overcoming the limitations may not be feasible~ On soils of this group -- (a) Loamy texture extends to a depth of at least 5 inches (12 em). {b) Periods of excessive soil moisture during the growing season do not ex- Cc~d a total of 3 weeks. (c) Damage by flooding occurs no more frequently than 3 years in 10. (d) Slopes are dominantly less than 20 percent. (e) Periods of soil moisture deficiency are frequent enough to severely dam- age crops. (f) Climat·ic conditions permit at least one of the common crops, usually grasses, to be grown successfully in most years. • .. . ' j J J I 1··· . . . I I TABLE 8.43: ECON<J.11CAL AND TECHNICAL SCREENING SOUTHERN STUDY AREA (WILLOW TO ANCHORAGE/POINT MACKENZIE) -Length Cm i I es) -Max. Elev. (ft) -Clearing (miles) - Medium & L!ght None -Acc~ss (miles) = Ne\\' Roads 4-Whue I -Tower Construction* -Rating: Economical Technical A = recommended corridor C = acceptable but not preferred F = unacceptable (1) (2) ABC' ADFC 73 38 1400 400 61 20 12 18 20 0 53 38 329 180 c A c A *Approximate number of towers required for thls corridor, assuming single-circuit line. (3) AEFC 39 400 15 24 12 27 176 c A TABLE 8.44: ECONOMICAL AND TECHNICAL SCREENING CENTRAL STUDY AREA (DAM SITES TO JNTERTIE) ( 1 ) (2) (3) (4) (5) (6) (7) (8) . (9) (10) (11) ( 12) ( 13) ( 14) ( 15) ABCD ABECD AJCF ABCJHI ABECJHI CBAHI CEBAHI CBAG CEBAG CJAG CJAHI JACJHI ABCF AJCD ABECF - -Length 40 45 41 77 82 68 75 90 ("5 91 69 70 41 41 45 -Max. Elevation, fi'. 2500 3600 3500 4300 4300 4300 3500 3300 3600 3500 3800 3900 2500 3500 3600 -Clearing Medium & Light 38 30 26 18 30 20 27 45 37 40 55 17 39 26 35 None 2 15 15 59 50 48 46 45 60 51 14 53 2 15 10 -Access New Roads 28 33 41 66 57 47 56 60 70 63 50 50 41 29 45 4-Wheel 12 12 0 0 0 0 0 28 27 2'8 0 15 0 12 0 -Tower Construction* 180 203 185 347 369 306 329 405 428 410 311 315 180 185 203 -Rating: Economical A c c F F c F F F F c F c A c Technical A c c F F F c c c c c c A A c A = recommended C = acceptable but not preferred F = unacceptable *Approximate number of towers required for this corr ldor, assuming single-circuit line. J .. , l J I , I ' , I ' I I' ' rjl • I ' ' I ' t I :f~ I i I -Length TABLE 8.45: ECONOMICAL AND TECHNICAL SCREENING NORTHERN STUDY AREA (HEALY TO FAIRBANKS} (1) (2) {3) ABC ABDC AEDC 90 86 115 {4) AEF 105 -Max. Elevation 1600 1600 4500 4500 -Clearing 50 40 Medium & Light 48 50 None 42 36 75 55 -Access New Roads 0 0 54 42 4-Wheel 90 43 42 16 -Tower Construction* 405 387 518 473 -Rating: Economical A A c c Technical A c F F A = recommended C = acceptable but F = unacceptable not preferred *Approximate number of towers required assuming single-circuit line. for this corrldor1 • • \ '• '•1 i.l li( ! I.' ' . i I ' . I I I I .I I f . l 'l ' . Ill 1M j TABLE 8.46: SUMMARY OF SCREENING RESULTS Corrl dor -Southern Study Area ( 1) ABC' (2) ADFC (3) AEFC -Cental Study Area Cl) ABCD (2) ABECO (3) AJCF (4) ABCJHI (5) ABECJHI (6) CBAHI (7) CEBAHI (8) CBAG (9) CEBAG {10) CJAG C 11) CJAHl Cl2) JACJHI ( 13) ABCF (14) AJCD ( 15) ABECF -Northern Study Area (1) ABC (2) ABDC (3) AEDC (4) AEF A = recommended Env. c A F A F c F F F F F F F f F A c F A c F F C = acceptable but not preferred F = unacceptable RAT NGS Econ. c A c A c c F F c F F F F c F c A c A A c c Tech. c A A A c c F F F c c c c c c A A c A c F F Summary c A F A F c F F F F F F F F F c c F A c F F • ' ' Corridor -] (AIIC'} 2 ~AOfC} l (AEFC) ' .. TABLE 8.47 .. ... .. EnvfrOMiental Constraints -Southern Siudy Area (WU Pow to Anchorage/Pofnt Mackerazte) Length 73 38 39 'I opo~raphy/ So f 1 s $Oijjij sons wltll severe 11•ftattons to off road travt15 s 'l!'lle SJQOd a gr f- 'cultural Goth ltlst of route potentially wt, with severe lt•ttatlons to off road travel; SOft good •yrt- cu1turil so ls Siae 11 Corridor 2 land Ust: 1RO existing ROW In AD; rESidential u~es near Pal~r; proposed Cdpltal stte; ~ch U.S. Hllltary Wdl.,Prlvate, and VI1Jaga Se1tcttOR hnd Tratl Is only exlattng ROW; re~identlal and recre1ttonal areas; Susttna flats Gome P~fuge; agricultural land ule NO ~nown extsttng ROW~ residential and rccre· ational use areas, fnctudtng Nancy Lakes; lakes used by float flanes; agricultural and sala Aesthetics lilltarod lr11l i tratl paralleling Deception Ck.: Gooding L. blrd- wltchtny nn' 5 cross ngs of Glenn tt.ty, 1 crossing of Parks lwy Susltna flats Gl111e Refuge; iditarod Traih I croutng of Parka tt.ly like area south of Wl11ow: ldttarod Tre n; 1 crosstng of Parks •hrly a. Coastal area probably has ~ny sites; IYIIllble literature not yet reviewed. b.. A • recD~Mended r. • acceptable b,t not rec~n.ended F • unacceptable Cultural Resources a Arcbiologic sites- dati votd Archeologtc sites- data Yotd Archeologfc sttes~ data ~td Vegetation lEEbnas along Deception Ck. and ~t Mltanuska River crossing; extensive cleartng In upltnd, forested areas net!lded Extensive wetlands; clearing needed 1n foNs ted areas Extensl~e wet1ands; clearing needed fn forested •r~as Fish Resources li river and 2lf creek crossings; valuable spawning sites, especially 1111100: kntk 1\rel HI tanush 1rea date votd 1 river and 8 creek cross tngs; valuable spawning sites. especially sa11101l: l. Sus Una R. data vo1d 1 river and 8 creek crossing~; va1uab1e spawning sftes, especially sa l1110n: l. Sus I tna R. data void 'I . .. Ytldltfe Resources Passes through or near waterfowl end shorebird nesting and feeding areas. and areas used by brown bear Passes through or near waterfowl and shorebird nesttng, feeding. and Mlgra- tton areas, and ereas used by furbearera tnd brown bear Sa.e IS Corrtdor 2 Envtronlflenta1 Rating b ---c A f ir : i -' ' j • .. . .. lengtf:1 Corr·ldor J!!!!lli.. ~!phy/Sotls_ 1 (ABell) 2 (ASECD) :J (AJCf) .. (ABCJJU) 40 45 41 77 Cro!l!in sevenl deep r.vfnes; cbout tooo• change tn elevation; sa.e t.~et soH!: Cross25 several deep rav lnes; .tbout 2000' change tn ell'2v.; s~ ste~ slopes; s~ wet sons· Crosses severa 1 ~ep ravines; about 2000• change In eJeutlon; SOllie steep slopes: soce wet sons ··~ 11!111. .. . TABLE 8.48 Env~ronmenta1 Constr~tnts -Central Study Are• (~ Sttes to lntert1e) Aesthetics 'cu1turi1 Resources ......0~--------- land Use Utt!e existing ROW except Corps rd. i 11t0st1y Yf11age Selection &nd Private l1nds fog lakes; Stephan lake; propcsed access road lttt1~ exlsttng Fog lakes; ROW ex~ept Crops Stephan take; rd. and at D; rec. propo~ed access and restd. areas; road; hf~ float plan~ areas; country (Pralrte mostly Y11iage & Chulttna Ck. Selection and drainages) and Prfvale Lands vtewshed of Alaska Range Ho ex1stl:-~g ROW except at f: rec. areas: float p hoe areas: .,st ly YH lage Selection and Private lind; resfd. " rec. development tn area of Otter l. and old sled rd. Ho ex ts t tng ROW; rec. areas and ho 1 a ted cab Ins; lakes used by float planes; mch YIUage Selection land Yfewshed of A lash Range & H~gh Lake; pro- pGsed access rd. fog lakes; Stephan Lab!; proposed &cccn rd; vfewshed of AlaskA Range Archeologtc sites ne~r Natana dam site, S~ephan late and Fog lakes; d1ta votd fro. Gold Creek to Devt1 C~nyon: historic sites ne(r the cowmunlttes of Gold Creek and Canyon Same as Cott ldor 1 Archeologlc sttes by Watana d~ site, & near Portage Ck./Susltna R. confluence; possJble sttes along Susttna R.; Htstortc sites near communities of Gold Ck. amf Canyon Vegetation Wetlands In eastern thtrd or corrfdor; extensive forest- clearfng needed Wetlands tn eastern half of corridor; edenstve forest- clearing needed Forest-clearing needed In western half F'sh Resources 1 r tver and 17 creek crossings; valuable · spawning areas, expeclally grayling: dah void 1 river and !7 creek crossings; valuabl@ spawn tng areAS • especially grayling: data void 14 creek crossing: valuable spawning areas,·especla11y grayling and sa1.an: • lndtan River Porhge Creek data void S.a11 wetland areas In Jl\ area; extens tve forest-clearing needed; dah void 1 river and 42 creek crossings; valuable . spawning areas, especIally grayJ fng · WC1d11fe Resources Env lroiWl!enta 1 Ratlng 1 Unidenllf8ed r•ptor nest loc~ted on trfb. to Susftna; passes through, h!bltat fort re~t~rsr furbearers, ~~~ves, wolve~tne, bro~ bear, caribou P1sses through habIt at ror: raptors, ~aterfowl, Migrat- Ing ~wans. furbearers, caribou, wolves, wolverfne, brown bear Golden eagle nest along DevH Clc. near High l.; active raven nest on Devil Ck.; passes through habitat for: rap tors, fut·bearers, wolves, brONO bear A f c c Crone-s several deep r1vfnes; >2000' ch•nge tn cleut ton; rout fng above 4000' ; steep slopes; SCtll!! wet sons; shallow bed- rock In 1ts. Archeo1ogtc sttes near Watana dM s fte, Stephan l. ,m!Jt Fog lDkesi possible sttes along pass between dratnages; data void between H and I Golden eagle nest along Devil Ck. ne~r High l.; caribou ~v~nt area; passes through habtt~t for: raptGrs, waterfowl, furbearers, wolves, wo her lne, brown bear 1. A ., •·ecOtMtended C • acceptable but not recommended f • unaccept.&ble • • 5 {Ai9ECJHI) 6 (CBNU) 7 (CEBAHI) 8 {COAG) BZ 68 73 90 C~o~ses set.~,!nl deep nvfnes: changes In el~v•tlon >2000•; rout lng •bove 4000': steep slopes~ SOD! .-,.t soils; shallow bedrodt fn •ts Crosses st:vertl deep nvtnes; changes fn eleYilt1on of about JEOO•; routing above 400f.l'; steep slopes: sor=e wet soils; shallow bedrock In •h. Crosses severtl deep rav lnes; chtnge In elevation of Jbout ltioo•; rout lng abo~te 3000'; steep slopes; SO!Qe wet 50t1s; sht11ow bedrock In 11t.s. Crosses S«•vera 1 deep nvtnes; chtn!)e In elev1tion of about 1600'; rout fng above 3000 • i deep s lop~s; s OllU! ;.;et so t 1s. sha J1ow bedrock In IJits. f il!!'""'~ .. TABLE B.48 CCONT 10) Envtron.ental Constraints -Central Study Ar~a (Da• Sttes to lntertfe) s~ .1$ tr-rr ldor 4 fog l•hs; Stephan Lake; Hfgh hl:e; proposed ICUSS rd; vtewshed at Aluh Ringe Ho known tudstfng fog hke11 111d ROW; rec. ireas Stephan lake; ~nd isolated proposed iCcess cabins; float rd.; Tsusena plane are~; Dutte; vlewshed Susltna area and of Alaska R~ge near I are Vl11~ge Sel~ctton land . . s..., 1s Corrtdor 6 Fog likes and Stephan lake: proposed .cess rd.; high country (Pralrfe- Chunnna Cks); Tsusena Butte; vlewshed of Ahsh Ringe Cultural Resour~s SMe as Corr t dor 4 Archeologlc sftes near Hatan~ da. sfte, fog lakes tnd Stephan l.; data void between H 111d I SMie u Corridor 6 Ho exhttog ROW; rec. areu lnd hohted cabins; f1o1t p lao~ ~rcas; 1lr strip and airport; rwch V H li!Jf! Selection and Federal land Fog lahs: Stepban take; ~cess rd; seen tc are• or Deatitan Clc.; vlewshed of Alash Range frcheologtc sites near Wat&nt d~ site, Fog Lakesl· Stephan lake and 1 ong Deadlwan Ck. f \•egeht ton fish Resources --Wlidllf~ Resources Wet: ~mds fr .. A iod Stephan lake areas; extens tva forest-clearing needed Edenslve wet- hnds frD• B to neat'" husena · Butte; ftxtenstve fores t-c !ear tng needed Extens fve wet- linds tn Stephin L. Fog Lakes, rsu:&ena Butte treas; .extenlive forest-clearing nee~ed Wetlands between 8 a»d·MOuntalns; extensfve forest- clearing needed 42 creek crossings: valuible spawning areas, especially grayling •nd sal.an: dah void Same as Corr ldor 4 wtth t~ort•nt waterfowl •nd algr•tlng sw~n hlbltat 1t StepiHin lake 32 cr~ek crossings; valuable spawning areas. especially griyllng: data told 45 cree~ 'rosslng; valu~bie spawning ~reas, especla!Jy grayl tng: dat4 vo ld 1 river and 43 creek crossings; valuable spawnIng are•s, expecl'ally grayling: data votd Bild eagle nest s.e. of Tsusena BuUe: area of Clrlbou .uv~nt; passes through habitat for: raptors,~terfowJ, fur- bearers, wolves, wolverine, brown bear Same as Corr ldor 6, wtth t~ortant·waterfo~l and •lgratlng sw1n hablt1t at Stephan lake Important bl1d eagle habitat by Denali »wy. and DeadMan l.; unchecked bald eagle nest near Tsusena Outte; passes through habitat for: raptors, furbearers, wolves, wolverine, browrt bur Env fronmenh 1 Ra~ lng F c F c length Corrfdor _(Hilesl Topography/Soils 9 (C£DAG) 10 (CJAG) 11 (CJNU) 12 (JA-CJIII) 95 91 69 70 Crosses set~eral deep ravfrtes: changes In elevatfon of about 1600': rout fng above 3000'; steep slopes: so..a wet sofls; shlll1ov bedrod fn •ts. SUJe as Corridor 8 . Crosses sever.11 deep ravines: changes fn e Jevat ton of 1000' ; rout fng above 3000' i steep slopes; SOliN! wet sons; shallow bedrock in llts. SAM@ at Corridor 11 land Use SaMe as Corridor 8 No exfstfng ROW; rec. 1reas and tsolated cabtns: float plane areas: afr strfp and afrport; IIIOStly Vflhge Select ton and FederaJ land No ex 1st fng ROW; rec. 1reu and tsol1ted cabins: f1oat t~hne · !re,u; iiiOsi iy VIllage Sel~ctlon and Private land Ho ~;c 1st lng ROW; ree. aren and tsohted cabins; float plane area: 1110stly YS11cge Selection and Private land l'~ TABLE 8.48 (CONT 1 D) Environment1l Constratnts • C@ntral Study Ar~: (D!~ s•t,~·to lntertte) Aesthetics Fog Lakes: Stephan Lake: proposed access rd: high country (Pralrte and Chunllna Cks.); Deadman Clc. ; vtewshed of Ahsh Range · Jffgh t.rllces area: proposed access rd.i Dealhan Clc. dratnage; view- shed at Alash Range fffgh lakes area; proposed 1cceu rd,; vfewshed of A lash Range High takes area; proposed access rd.; Tsusena Butte; vle\#shed' of Ahsh Range Cultural Resources Selllrl! As Corr fdor 8 Arc~eologfc sites near Watana d~ sfte. and along DeadMAn Ck. Archeolootc sites near Watana daM site Archeologfc stte nEar Watana daM stte; possible sites along p~ss bet~een drainages Vegetatfnn Nethnds fn Stephan l./Fog lakes areas; extensive forest• cle1rtng needed S..a 11 wet lands In JA area; extensive forest~ during f!l!eded Sftla11 wetland areas In JA area; SOMe forest-clearing needed S=a11 wetland areas tn JA ari!a; fairly e.lltens tve forest clearing r.eeded FIsh Resources . 1 river and 48 creek r.rosstng~; valuable spawning areas. expeclally gr~y1fng: d1t2 votd 1 rfver and 47 creek crossings: valuable spawn fng areas~ expeclally grayling: data votd 36 creek crossings; valuable spawning areas, espec1ally ·gnyl tng and uJ110n: d•ll void ~0 creek crosstngs: va'luab le spawn lng areas, especially grayling and salaon: dati void Wildlife Resources Environmental Rating SaMe as Corridor 8p with l~ortant waterfowl and Migrating swan habitat at Stephan lake Golden eagle nest along Oe~ll Ck. near High lak~: unchecked bald eagle nest near Tsusena Butte: area of caribou move- Ment; passes through ~ablt~t for: raptorsa waterfowl, furbearers, brown bear Golden eagle nest along Devil Ck. near High lake; b1ld ~igle oest s.e. or Tsusena Butte; passes through habftat for: raptor~, furbearers, brown bear Golden eagle nest along Oe~fl Clc. rvear High lake; passes through habitat for: raptors, furbearers. ~lves, bro.) bear F r. c f r. ~ ) . ( ' ' . ~·· .. TABLE 8.48 (CONT'D) Envtr~ntal Constraints • Central Study Are1 (Da• Sltfs to f~t~rtie) length Envfron~nhl Corrtdor (HUes) To~Jrephl/Soi1~ land Us!! Aesthetics Cultural Resources Vesetatlon fIsh Resources; Wlldl tfe Resources Rating 13 41 Crosses several Ho known existing Fog Lakes, Archeoluglc sites near Wethnds tn 15 creek crossings; Unidentified r•ptor nest " (AllCf) deep ravl~s; ROW except at f; Stephan l. ~ '~•hna dant s lte, eastern lh trd va1uab1e spawning on tributary to Susttna; about 1000@ rec. lre&s; float proposed access Portage Ck./Susltna R. of corridor; &reas, especially ptsses through• habitat fo~: change In plahe areas; rd. confluence; Stephan L., extensive grayltng and sal.on: raptors, furbe~rers, wolves, e lev at I on; SCli1!!e resfd. and rec. and fog lakes; historic forest-chtartng lndlan River ., 1 ver tne, brown bear, wet sons use near Otter sites; near co.munltles neQded Porhge Creek caribou L. and old sled of Canyon and Gold Ck. data voCd rd.; isolated . cablnsi mostly Yltla~ Selection Land; so.e Private land 14 41 Crosses deep lfltle exist 5ng Vlewshed of Archeologlc sites by Forest·c~eArlng l rfver .,,d .16 creek Golden eagle nest In Devil A {AJCO) rav lne &t .Dev n ROW except old Ahsh Ringe Wit ana d• sIte, needed tn weJtern crossings; va1uab1e Ck./Htgh late 1rea; 1ctlve Ck.; about 2000' torgs rd. ~nd and IHgh Like: possible sites Along hllf spawntny arus, rat· 1 nest on Oevt1 Ck.; change tn •t ; rec. areas; proposed :.teen Susltn• R.; historic especla ly grayling: pas~es through habitat fof: elevation; routing IsolAted Cib•ns; road sites r~ar communities data void rdptors, furbearers, .u•ves, Jbove 3000'; SOlie IIIUCh V 11 hge of Canyon 1nd Gold Ck. brown bear. caribou steep slopes; Selection land; SOIIQ wet soli~ soc.e Prfnte L1nd 15 45 Cros$eS several "o known existing fog like$; S~~~e as Corr tdor 13 Wetlands In lS'creek crossings; IMportant waterfowl iPd f (ADECf) deep nvfne5; Rail except at F; Stephan Lake; eastern half valuable spawning •lgratlng swan habitat about 2000' ch .. ;.~e rec. are1s; float proposed access of corridor; 1r~as. especially at Steph1n L.; passes tn elevat toni plane ireas; road; hi~ extensive forest-grayl!r.g and sal~n: t~rough habttat for: SOllie wet. so I s ~res fd. in& rec. country Prairie clearing needed Jndta1t R lver raptors, waterfowl, use nen Otter and thun ln• Cks. Portage Creek furbearers, wo i ve s & L. and old sled drainages); d•h void wolverine, brown beir, rd.; lsohtet~ vlewshed of caribou . cabins; .aslly Alaska Rtnge Vllhge Selectlcm hnd with SMM! Prlvite Lind ;f ' (' .. _ ....... Corridor • (ABC) 2 (ABOC) 3 {Atilt) 4 (A£f) --- •, TABLE 8.49 Environmental Constra~nts -Northern Study Area (Healy tu Fatrbanks) Lenfth (fit es) Topography/Sons land Use Aesthetics ""00-Some wet soils IUF stftj); 3 cross 1n!;s of wfth severe rtstdent1al areas Parks Hwy; 1taw1tatfons to and tsolated cabins; Nenana R.-otr~road trafffc so~ U.S. Htlftary scl!n1c area Wtthdraw1 and Nattve land ·86 Severe lf•ftattons Ho existing ROW ~. 3 crossings of us 105 to off-road traffic in wt sons of tiNt flits Change !n elevotfon "' about 2500*; steep .slopes: shallow bedrock in ~ts.& severe lt~lt­ atfons to off-road trafrtc tn the flats Sa~ .u Corridor 3 of Bro~e• scattered restdentfal and 1solated cabfns; ~trstrip; fort Wainwright Hf11tary Reser- vatton No existing ROW beyond Healy/Cody Ck. confluence; holated cabins; afrstr1ps; Fort Wainwright Hi11tary Reservation Afr,trtpsi isolated cabins; Fort Wmtn- wrtgbt HlJ Uary Rest!rva tt on r Parks ftwy; high vbtbtHty in open fl&l ts 1 cross tng of Parks J~y; htgh vhlbll tty tn open flats Hfgh vtsibfllty tn open flats a. Source:.VanBal~~nberghe personal c~icatton. Prime habftat • MtntmuM. a~unt of land necessary to provide a sustained yield for 1 spectes1 ba~ed upon knowledge of thJt specfes• needs frDN upertence of ADF!G Personnel. lll'lpOrtant habitat • bnd Nhtch ADF&G considers not as crtttcaJ to 1 specie~ ~s ts Priae habitat but ts vaJuible. ' b. A • ret~nded C • &ccept~ble but not preferred f .. un~eceeJlable Cultura~ Resources ~rcfieologic sites probable since there h a known Jite nearby; data votd . Dry Creek ercheoloyic stte near llea.y; possible sttes along river crosstngs; data vofd Cry Creek archeo1ogtc Jfte .near flealy: J:'OSSible slh!S near Japan H111s and in the 1111ts.; dlltll \!Ufd Archeologtc lites near Dry Creek and fort Wainwright; possible sttes near Tanana River: data vofd l Vegetation . E~tensfve wetlands' forest clearing nfeded ~natnly north o'" the Tlnf.:ll Rher . Probably extensive wetlands between Wood and Tanana Rivers; extenstve forest clentng needed n. of Tanana Rtver frobably e•tenstve wetlands b2tween Wood and Tanana Rivers~ a~tenstve forest clt!&rfng needed n. of Tanana River; data lacking for southern part Probably ext~nsfv~ wetlands ~~tween Wood and T~'i1111 Rhers. Fhh Resources ~ river and 40 creek crossings~ valuable spa"'" i ng s ite5: Tanana River data void 5 river and 44 cre~k crossing$; valuable spawning s1tt!s: Wood River dati votd 3 rfver and 72 creek crossings; valuable spa~rm i ng s ftes: Wood Rfver data vo1d 3 river and 60 creek crossings: valuable spawning sites: Wood Rtver data wfd Utldl He P.:;::;otJrces 8 £nvttonlll(! Pi~~es-through or near prt~ habitat for: peregrines, waterfowl, furbearers. lltOOSe; passes through or near i~~~porhnt habit;t for: pere- grtnes, golden eagles Passes through or near prtme habStat for: peregr1 nes. waterfowl, forbearers; passes through or near important habttat for: golden eagles& other raptors Passes through or ncar prime habttat for: peregrines, waterfowl. furbearers, car,fbou, sheepi passes through or near- t~nportant habitat for: golden eagles, brown bear Passes through or near prfme habitat for:peregrlnes, bald eagles, waterfowl, fu•bearers, carfbo~. sh~ep; passes through or near Important habitat for: golden eagles, brown bear Aatln· A c F c • • Technical Primary Secondary Economic Primary Secondary Environmental Primary Secondary TABLE 8.50: TECHNICAL, ECONOMIC AND ENVIRONMENTAL CRITERIA USED IN CORR I Dffi SCREENING Topography Climate and Elevation Soi Is Length Vegetation and Clearing Highway a~1d River Crossings Length Prese\lce of Right-of-Way Presence of Access Roads Topography Stream Crossings H l ghway and Ra II road Cross i ngs Aesthetic and Visual Land Use Presence of Existing Right-of-Way Existing and Proposed Development Length Topography Soils Cultural Reservoir Vegetation Fishery Resources Wildiife Resources TABLE B. 51: WATANA ESTIMATED NATURAL FLOWS YEAR OCT NOV IIEC JAN FEB MAR AF'f\ MAY JUN JUL AUG SEP 1950 4719. 9~ 2083.6 1168.9 815.1 641.7 569.1 680.1 8655.9 16432.1 19193.4 16913.6 7320.4 1951 3299.1 1107.3 906.2 ao8.o 673.0 619t8 1302.2 11649~8 185l7t9 19786.6 16476.0 17205.5 1957.( 4592.9 2170.1 1501.0 1274.5 841.0 735.0 803.9 4216.5 25773.4 22110,9 17356.3 11571.0 1953 6285.7 2756.8 1281.2 818.9 611.7 670.7 1302.0 15037.2 21469.8 17355.3 16681.6 11513.5 1954 4218.9 1599.6 1183.8 1087.8 803.1 638.2 942. C.1 11696.8 19476.7 16903.6 20420.6 9165.5 1955 3859.2 2051.1 1549.5 1388.3 1050.5 886.1 940 .t] 6718.1 24801.4"23787.9 23537.0 13447.8 1956 4102.3 1588.1 1038~6 816.9 754.8 694.4 718~3 12953.3 27171.8 25831.3 19153.4 13194.4 1957 4208.0 2276.6 1707.0 1373.0 1189.0 . 935.0 945.1' 10176.2 25275.0 19948.9 17317~7 14841.1 1958 6034.9. 2935~9 2258.5 1480.6 1041~7 973.5 1265.4 9957.8 22097.8 19752.7 18843.4 5978.7 1959 3668.0 1729.5 1115.1 1081.0 949.0 694.0 885.7 10140.6 18329.6 20493,1 23940.4 12466.9 1960 5165.5 2213.5 1672.3 1400.4 1138.9 961.1 1069.9 13044.2 13233.4 19506.1 19323.1 16085.6 1961 6049.3 2327.8 1973.2 1779~9 1304.8 1331.0 1965.0 13637.9 22784.1 19839.8 19480.2 10146.2 1962 4637.6 2263.4 1760.4 1608.9 1257.4 1176.8 1457.4 11333.5 36017.1 23443.7 19887.1 12746.2 1963 5560.1 2508.9 1708.9 1308.9 1184.7 883,6 776.6 15299.2 20663.4 28767.4 21011.4 10800.0 1964 5187.1 1789.1 1194.7 852.0 781.6 575"2 609.2 3578.8 42841.9 20082.8 14048~2 7524.2 1965 4759.4 2368.2 1070.3 863,0 772.7 807.3 1232.4 10966.0 21213.0 23235.9 17394.1 16225.6 1966 5221.2 1565.3 1203.6 1060.4 984.7 984.7 1338.4 7094.1 25939.6 16153.5 17390,9 9214.1 1967 3269.8 1202.2 1121.6 1102.2 1031.3 889.5 849.7 12555.5 24711.9 21987.3 26104.5 13672.9 1968 4019.0 1934.3 1704.2 .1617.6 1560.4 1560.4 1576.7 12826t7 25704,0 22082vB 14147,5 "7163,6 1969 3135.0 1354.9 753.9 619.2 607.5 686.0 1261.6 9313.7 13962.1 14843.5 7771.9 4260.0 1970 2403.1 1020.9 709.3 636.2 602.1 624.1 986.4 9536t4 14399,0 18410.1 16263.8 7224.1 1971 3768.0 2496.4 1.687.4 1097.1 777.4 717.1 813.7 2857.2 27612.8 21126.4 27446.6 12188.9 1972 4979.1 2587.0 1957.4 1670.9 1491*4 1366.0 1305.4 15973.1 27429.3 19820.3 17509.5 10955.7 1973 4301.2 1977.9 1246.5 1031t5 1000,2 873.9 914.1 7287.0 23859.3 16351.1 18016.7 8099.7 1974 3056.5 1354.7 931.6 786.4 689.9 627.3 871.9 12889.0 14780.6 15971.9 13523.7 9786.2 1975 3088.8 1474.4 1276.7 1215.8 1110.3 1041.4 1211.2 11672.2 26689.2 23430.4 15126.6 13075.3 1976 5679.1 1601.1 876.2 757.8 743.2 690.7 1059.8 8938.8 19994.0 17015.3 18393•5 5711.5 1977 2973.5 1926.7 1687.5 1348.7 1202.9 1110.8 1203t4 8569.4 31352.8 19707.3 16807.3 10613.1 1978 5793.9 2645.3 1979.7 1577.9 1267.7 1256.7 1408.4 11231.5 17277.2 18385.2 13412.1 7132.6 1979 3773.9 1944.9') 1312.6 1136.83 1055.4, 1101.2 1317.9312369.3122904&8 24911.7 16670.7 9096.7 1980 6150.0:! 3525.0 2032.0 3 1470.0 1233.0; 1177.0 3 1404.0.,10140.04 23400.0.1 26740.0~ 18000.0211000.02.. 1981 6458.02. 3297.02 1385.04 1147.0i 971.0 889.04 1103.0 10406.0 17323.0 27940.0 31435,0 12026.0 AVE 4513.1 2052.4 1404.8 1157.3 978.9 898.3 1112.6 10397.6 22922.4 20778.0 18431.4 ~0670.4 Notes: ( 1) D ischsrges based on Cantwell a1d Gold Creek flows unless specified (2) Watana observed flows (3) Flowe based on Gold Creok (4) Watana long-term average flows assumed •. c AVE 6599t5 7696,1 7745.5 7908.7 7351.4 8674.8 9001~5 83ll9.4 7718,4 7957.7 7901.2 . 8551 t 6 9799.1 9206.1 8255.4 8409,0 7345.9 9041.5 7991.4 4880.8 6068.0 8549.1 8920.4 7079.9 6272.5 8367.7 6788.4 8208.6 6947.4 13133.0 0855.9 9523.3 7943.1 TABLE 8.52: DEVIL CANYON ESTIMATED NATURAL FLOWS YEAR OCT NOV IrEC JAN FE£1 MAR Af'R HAY JUN JUL ~UI3 SEP AVE 1950 5758.2 2404.7 1342.5 951.3 735.7 670 .. 0 802.2 10490.? 18468.6 21383.4 18820.6 7950;.8 7431.6 1951 3652,0 1231 t 2 to3o. a. 905.7 767.5 697:-1 1504~6 13218.5 19978.5 21575.9 18530.0 19799.1 8574.2 1952 . 5221!7 2539.0 1757.5 1483.7 943.2 828.2 878.5 4989.5 30014.2 24861,7 19647.2 13441.1 8883.8 1953 7517.6 3232.6 1550*4 999.6 745.6 766.7 153t. a 17758.3 25230.7 1~104.0 19207.0 13920.4 9304.4 1954 5109.3 1921.3 1387.1 1224.2 929.7 729.4 1130.6 15286o0 23188tl 19154,1 24071.6 11579.1 8809.2 1955 4830.4 2506,R 1668.0 1649.1 1275.2 1023.6 1107 ··1 8390.1 28081.9 26212.8 24959.6 13989.2 9657.8 1956 4647.9 1788.6 1206.6 921.7 893.1 852,3 867.3 15979.0 31137.1 29212.0 22609.8 16495.8 10550.9 1957 5235.3 2773.8 1986.6 1583.2 1388.9 1105.4 11·C9 • 0 12473.6 28415.4 22109.6 19389.2 18029.0 9633.3 1958 7434.5 3590.4 2904.9 1792.0 1212.2 1085.7 1437.4 11849.2 24413.5 21763.1 21219.8 6988.8 8807.6 1959 4402.8 1999.8 1370~9 1316.9 1179.1 877.9 1119.9 13900.9 21537~7 23390.4 28594.4 15329.6 9585.0 1960 6060.7 2622.7 2011.5 1606.2 1340.2 1112.8 1217.8 14802.9 14709.8 21739.3 22066.1 18929.9 9025.0 1961 7170.9 2759.9 2436.6 2212.0 1593.6 1638.9 2405.4 16030.7 27069.3 22880.6 21164.4 12218.6 9965.1 1962 5459.4 2544.1 1978.7 1796.0 1413.4 1320.3 1613.4 12141.2 40679.7 24990.6 22241.8 14767.2 10912.2 1963 6307.7 2696.0 1896t0 1496.0 1387.4 958.4 810.9 17697.6 24094.1 32388.4 22720.5 11777.2 10352.5 1964 5998.3 2085.4 1387.1 978.0 900.2 663.8 696.5 4046.9 47816.4 21~26.0 15585.8. 8840.0 9243.7 1965 5744.0 2645.1 1160.8 925,3 828.8 866.9 1314.4 12267.1 24110.3 26195.7 19709.3 18234.2 9506.8 1966 6496.5 1907.8 1478.4 127G.7 1187.4 1187.4 1619.1 9734.0 30446.~ 18536.2 20244.6 10844.3 8663.4 196.7 3844.0 1457,9 1364.9 135:1.9 1268.3 1089.1 1053.7 14435.5 27796.4 25081.2 30293.0 15728.2 10397.5 1968 4585.3 2203.5 1929.7 1851.2 1778.7 1778J7 1791.0 14982.4 29462.1 24871.0 16090.5 8225.9 9129.2 1969 3576.7 1531.8 836.3 686.6 681.8 769.6 1421.3 10429.9 14950,7 15651.2 8483.6 4795.5 5317.9 1970 2866.5 1145.7 810.0 756.9 708.7 721.8 1046,6 10721.6 17118.9 211A2.2 18652.8 8443.5 7'011.3 1971 4745.2 3081.8 2074.8 1318.8 943.6 866.8 986.2 3427.9 31031.0 22941.6 30315.9 13636.0 9614.1 1972 5537.0 2912.3 2312.6 2036.1 1836.4 1659.8 1565.5 19776.8 31929.8 21716.5 18654.1 11804.2 1015.1.8 1973 4638.6 .1154.8 1387.0 1139.8 1128.6 955.0 986.7 7896.4 26392.6 17571.8 19478.1 8726.0 7704.6 1974 3491t4 1462.9 997.4 842.7 745.9 689.5 949.1 15004.6 16766.7 17790.0 15257.0 11370.1 7113 •. 9 1975 3506.8 1619.4 1486.5 1408.8 1342.2 1271.'9 1456.7 14036,5 30302.6 26108.0 17031.6 15154.7 9567.1 1976 7003.3 1853.0 1007.9 896.8 876.2 825.2 1261.2 11305.3 22813.6 18252.6 19297.7 6463.3 7654.7 1977 3552.4 2391.7 2147.5 1657.4 1469.7 1361.0 1509.8 11211.9 35606.7 21740.5 18371.2 11916.1 9411.3 1978 6936.3 321o.e 2371.4 1867.9 1525.0 1480.6 1597el 11693t4 18416.8 20079,0 15326,5 8000.4 7715,4 197~ 4502.3 2324.3 1549.4 1304.1 1203,.6 1164.7 1402.8 1?~:4.0 24052.4 ~7462.8 19106.7 10172.4 8965.0 198 6900.0 3955,0 2279.0 1649.0 1383,.0 1321.0 1575.0 11377.0 26255.0 J0002.0 20196.0 12342.0 9936.2 1981.1f 7246.0 3699.0 1554.0 1287.0 1089,0 .997.0 1238.0 11676.0 19436,0 31236.0 35270.0 13493.0 10685.1 . AVE 5311.8 2382.9 1652.0 1351.9 1146.9 1041.8 1281.5 12230.2 25991.3 23100.9 20709.0 12299.2 9041.6 . * Discharges baaed on Watana flows .. .. • TABLE B~53: MONTHLY FLOW REQUIREMENTS AT GOLD CREEK I MTH A A1 A2 c Cl 0 2000 2000 2000 2000 2000 I N 1000 1000 1000 1000 1000 D 1000 1000 1000 1000 1000 J 1000 1000 '1000 1000 1000 f 1000 1000 1000 1000 1000 M 1000 1000 1000 1000 1000 A 1000 1000 1000 1000 1000 M 2000 4000 5000 6000 6000 J 2000 4000 5000 6000 6000 J 1 2000 4320 5400 6480 6650 A 2000 8000 10000 12000 14000 s2 2000 6200 7750 9300 10400 l No-tes: Derivation of transitional flows. 1 2 July = (June x 26 + 5 [ June+ August)) 2 31 Sept= (August x 14 + 5 I June+ August) +June x 11) 2 C2 2000 1000 1000 1000 1000 1000 1000 6000 6000 6810 16000 11500 1 30 • • D 2000 1000 1000 1000 1000 1000 1000 6000 6000 7050 19000 13150 ~ TABLE B. 54: ENERGY POTENTIAL OF WATANA -DEVIL CANYON DEVELOPMENTS FOR DIFFERENT DOWNSTREAM FLOW REQUIREMENTS ENERGY P 0 T E N T I A L G W H WATANA 0 N L Y WATANA & D E V I L CANYON FIRM ENERGY AVERAGE ENERGY FIRM ENERGY AVERAGE ENERGY MONTH CASE A c D A c D A c 0 A c D OCT 244 221 180 296 263 185 482 610 590 548 610 587 NOV 269 243 197 340 322 321 528 472 410 678 635 473 " DEC 315 285 231 407 388 323 617 551 480 801 770 645 JP.N 288 260 21 1· 356 346 316 564 504 439 742 717 646 FEB 224 202 164 .. 291 283 266 438 392 341 638 616 513 MAR 250 226 278 290 286 276 490 438 381 628 614 527 APR 209 189 267 253 250 248 409 366 319 516 507 483 MAY 200 182 211 266 258 251 423 4011 338 484 445 425 JUN 183 165 152 236 227 215 363 324 282 440 429 441 JUL 187 169 209 216 205 196. 371 332 288 424 405 398 AUG 196 303 324 286 373 588 390 479 1543 495 581 85!,; SEP 200 266 179 239 274 354 394 1')9 569 536 579 1T! J - TOTAL 2765 2711 2603 3476 3475 3449 5469 5338 4980 6930 6908 6771 NOTE: Cases Band C were similar and only Case C was analyzed In detail. • \ • C· • ~·c,' ~ ~ , _ _;--.__,_,.r------'--~--· ---~----~-------..----------··---·-·_:.,....._ __ --~~-~- I T: TABLE 8.55: NET BENEFITS FOO. SUS IT~ HYDROELECTRIC PROJECT OPERATING SCENARIOS I LTPWC* NET BENEFIT PERCENT t Decrease 6 6 Relative (1982 dollars x 10 \ ( 1982 do i I ars x 10 ) to Case A I I Thennal Opt ton 8238 Case A 7023 1215 Case At 7037 1201 1 t Case A2 7049 1189 2 Case C 1091 1141 6 L Case C1 7180 "1058 13 Case c 2 7329 909 25 Case 0 7574 664 45 *Long-Term Present Worth Costs "'~ I I • I I I L L ....... --~-.-· -~---~-_,.......,_ .. __ _.,__ --.. ---·---"'~~-----------~-~-----------~~ -~--'-·- 0 !ABLE 8.56: AVERAGE ANNU~L AND MONIHLY FLOW AT GAGE IN THE SUSITNA BASIN* STATION (USGS Reference Number Sus Jtna River Susltna River at Go I d Creek Near Cantwell (2920) (2915) MONTH Drat nage Area 6160 4140 sq. mt .. % Mean(cfs) J Mean(cfs) JANU\RY 1 1,474 1 824 FEBRtJa.RY 1 1,.249 1 722 t-!ARCH i 1, 124 1 692 APRIL 1 1,362 1 853 MAY 12 13,240 10 7, 701 JUNE 24 27,815 26 19,326 JULY 21 24,445 23 16,892 AUGUST 19 22,228 20 14,658 SEPTEMBER 12 1~321 10 7, 800 OCTOBER 5 5, 771 4 3,033 NOV8·1BER 2 2, 577 2 1,449 DECEMBER 2 1,807 1 998 ANN~L -cfs 100 9, 753 100 6,246 Period of Record -Gold Creek -195Q-81 Cantwell -1961-72 Denal t -1957-79 Maclaren -1957-79 '*· Ref. USGS Stream-f I ow Data Susftna River Near Danai I (2910) 950 % Mean(cfs) 1 244 1 206 1 188 1 233 6 2,036 22 7,285 28 9,350 24 8,050 10 3,350 3 1,122 2 490 1 314 100 2,739 ) Maclaren River Near Paxson ~1912) 280 % Mean(cfs) 1 96 1 84 l 76 87 7 803 25 2, 920 27 3, 181 22 2,573 10 1,149 3 409 1 177 1 118 100 973 ' " • ,~, ~---~-'"''" TABLE 8.57: PE~K FLOWS OF RECORD Gold Creek Cantwell Dena! J Maclaren Peak Peak Peak Peak 3 3 3 3 Date ft /s Date ft /s Date ft /s Date ft /s 8/25/59 62,300 6/23/61 30,500 8/18/63 17,000 9/13/60 8, 900 6/15/62. 80,600 6/15/62 47,000 6/07/64 166 000 6/14/62 6,650 6/07/64 90, 700 6/07/64 50,500 9/09/65 i 5, 800 7/18/65 7,350 6/06/66 63,600 8/11/70 20,500 8/14/67 28,200 8/14/67 7,600 8/15/67 80,200 8/10/71 60,000 1!21/68 19,000 8/10/71 9,300 8/10/71 87,400 6/22/72 45,000 8/013/71 38,200 6/17/72 1, too TABLE 8.58: ESTIMATED FLOOD PEAKS IN SUSITNA RIVER ' l --Location Peak Inflow in Cfs for RecurrE rJC2_ I nterve: I in Years 1:2 1:50 1:100 1:10,000 PMF - Gold Creek 49,500 106,000 118, 000 190,000 408,000 \, Watana Damsfta 40,000 87,000 97,000 156,000 326,000 Oevll Canyon Damsite ) 12,600 39,000 61,000 165, 000 345,000 (Routed Peak In f I ow ) with Watana ) ; . TABLE 6.59: WATANA FLOOD ROUTING -MAXIMUM FLOWS (cfs) WATANA FLOOD ROUTING Maximum Flows During Flood (cfs) Splllway Flood Powerhouse Outlet Main Emergency Total 1: 50 7000 24,000 0 0 3100 1:10,000 7000 24,000 119,000 0 150,000 PMF 70006 24,000 150,000 11911000 293,000 DEVIL CANYON FLOOD ROUTINGb Maximum Flow D.u r t ng Flood (cfs) .... Spillway F I ood Powerhouse Outlet Main Emer Tota I - 1; 50 3500 35,~00 0 0 39,000 1:10,000 3500 38,500 12~.,000 0 165,000 PMF 3500c 3A,500 156,000 150.000 345,000 No-tes: a b Powerhouse clo?es when reservoir level exceerls 2193 ft MSL Assumes Watana Reservoir apstream Powerhouse closes when roservotr level exceeds 1456 MSL c Maximum Reservlor Level (f"t) 2193 2193.5 2201.0 Maximum Reservoir Level ( ft) 1455 1455 1466 .. \ L. TABLE 8.60: ESTI~l'ED EVAPORATION LOSSES -~~TANA AND DEVIL CANYON RESERVOIRS -WATANA P::m Reservoir Evaporation Evaporation Month (Inches) (Inches) - January 0.0 0.0 February 0.0 0.0 March 0.0 0.0 April 0.0 0.0 May 3.6 2.5 June ;i4 2.4 July ~3 2.3 August 2.5 t. 8 September 1. 5 1. 0 October 0.0 a.o November a.o a.o December o.o o.o -- Annual Evap., 14.3 1 0., 0 ~Based on data -April 1980-June 1981 3 Based on data -Ju I y 1980-June 1981 Based on data -January 1941-December 1980 ........ ... ,. D E V I L Pan Evaporation (Inches) 0.0 0.0 a.o uo 3.9 3.8 3.7 2.7 1. 7 t\ 0 (l,Q o. 0 - 15.8 CANYON Average Month I y A I r Temperature < •c) Reservoir EvaporatIon (Inches) Watana 1 Dev I I Canvon 2 Talkeetna3 (10 -2.5 -4.5 -1~ 0 0.0 - 7 .. 3 -5. 0 -9.3 a.o -1. 8 -4. 3 -6, 7 0.0 -1. 8 -2.5 0.7 2.7 8.7 6. 1 7. 0 2.7 lU. 0 S\2 12. 6 2.6 13. 7 11. 9 14. 4 1. 9 12. 5 N/A 12.7 1. 2 N/A 4.8 7. 8 0.0 0.2 -1. 8 Q.2 a.o -5. 1 -7. 2 - 7 .. 8 o. 0 -17. 9 -21. 1 -12.7 - 11. 1 I } l I v~, ! l l I I l I \ I \: l l" \ \ • l: \'' ~~-l.' l TABLE 8.61: FLOW RELEASE (CFS) AT WATANA FOR WATANA ONLY -CASE C . OCT NOV J)EC ,JAN f'F.B iiAR APR 1 . rl664, 6 97l·6c 3 1128~) ~ 3 970~) c 6 8)'~)8 I 2 BOBO.B 738:~ I 7 2 ~)(~41). 9 th~.,o. 7 77 !,~) t) 71H9,9 6290,() b4,SU) :1 ~)(,74. :-s 3 7082.9 10164{1 11617.4 lOl b~h 0 9P'7 I .,"1 • ,, 8241.~. 7 7r:07 r. ~) C\) 4 ·B269,3 10750.7 11397.6 9709e4 8928.2 RiB2c4 BOFHit 6 5 r.· 691 ') ,, . "'· (;!)'11. 6 11~i00) I. 9978 ~ ~s 9119.lt 0149.1 / 7646.'/. 6 5684.0 7246 t l 11665.9 10278c8 9~~67 c(J a~~97, a 7644c4 7 762.0. () 9582.1 l1155 ,·(, ~707c4 9(li'lo3 B20bc1 74~1.9 B T/7~~ r• . ' I ,) 1 ()270. ~j 11H2:i. "i 1 0?.6:i. ~i 9r.' )r.· r.• ,) ' ,} . ,) B44,S • 7 7!.48~7 9 9605.4 10929.9 12374.9 10:i71c1 9358~2 8485,2 7969.0 10 5731.9 6~'il2.7 7772«5 9971.5 9~!65. 5 8205.7 7589 I:; 11 8736.0 10207.4 l17B8.7 10290.9 94···-4 ,) ,) ! B4i'2c8 t77:i I f) 12 f.4B2, 7 10321.7 12089.6 10670.4 96?1.:3. B842~7 Bl~6a, /, 13 6f)~jf)) :-s 1 ()(.~)7) :; 11s7,s.a 10499.4 9~i7:-s. 9 Hb8H, ~) fH,Sl, 0 14 9130.6 10502.9 ll825.3 10199c4 950l.2 s:i95. 3 7~80.?. 15 6516.0 9783 .l 113l1d 9742.5 9098.1 BOB6.9 7:H2 c B 16 5759.3 6535.8 7538.2 S'r:'60 ~ ,) . I '""t 9089c2 ·a;u 9 c{) 741'36.0 17 8791.7 9559.3 11320.0 9'150.9 9:~01c 2 8496c4 8042 c(l Hl r7'1?_ ~~ ,) (, . ) . 6~)1)4, a 7606 .:~ 9992.7 9:~4 7 dJ 0401.2 7r.··-~~ ~i ~l ,) • • • 19 7589.5 992Bc2 11820.6 10508.1 ~'B'J6 c 9 9(l72c1 82fJ() I:~ 20 5756.8 6543.1 7573.0 7636.5 9064.5 8197.7 7r:•r•3 6 ,)~ .. :!1 fl907 I 9 /.809. 4 /S56c2 7:~30. 4 6420.?. 61,1 y, () !iH26, 2 ,, ..... 5971.4 6790,2 7879.0 7:~36. ~~ 64l9c1 6b14eB r.·a" '5 1 ,) 2~ c 2.~ 7H6C)" 2 1()~)81)) 9 1 ~~073 .{~ 1 ')~i,~ L ) 4 YBI)7,9 UU/7,7 B~)•)9, 0 24 !\697.0 6589.5 ll3r•2c9 9'122,() Cf~Ho, 7 a:;Rr•, b 7617.7 2S 5780,5 6573.2 7622.2 7091.7 6638.2 B139.0 7r: 7r:. . ~· ,) .) c ~ 26 590lc1 ~782.7 78llc4 7274,2 n:i~Hi, 6 6~)37 c () :i739.0 27 77'Jn, J 9t'i95 .1 l 099:?. t,.. 9648.3 9059.7 8202.4 776:~ t 4 2H ~iH27' 7 ()62H •.1 /,S77 ,() 7l~i~),9 ,, ?.~i 1) 4 7~)'J:s. 1 79c)7. 0 29 5692.1 9198.0 12096.1 104b8c4 9~)84 c 2 8768.4 H1l2 c,O 30 5881.8 6683.9 7750.7 7215.6 6306.8 6477.9 ~)679 c () 31 56Bj,2 1130~.1 12148.4 103~0.5 ~'549 c 5 8688.7 9107.6 32 9053c3 11290.9 l150lc4 10037c5 9~87c5 8"00.7 7H06c6 it' MAY ,JIJN .JlJL •. 6 'J2 IM ,, • •• f ,, 4853.9 46l7.4 7a74.1 4~1~ir.' r.· ' . ,) . ,) ~778d . 5:~21H H ~)00:? I 3 479/c'l.. 11 ~~]~j I h 49~)9 c 6 ~ ~)60 I 9• H~169. :i A}9,S?..?. 4t)9C). (i L•2a• 8 9 ,, -,) ' r)174.6 6849.6 ~'~H•O, l 90HU,6 BB1Hc7 71)00. 7 712:~.; 474H.~l IIB04 I 2 4~'/,:~. n 47ri5.7 696Hc7 4B:~a. ~ 4780.9 9~581 c 9 4870.4 4812.9 10116 c :~ ··2( ·~ 'J ,) . ) ' c ' 4747c4 {il)42. :-s 1Ml98, 'J ~~i7'l I •} l16i1.4 -\9~9.4 95ln.9 ''3'"1 1 ,), ,., . . u:n· .. ~ ~-•• ~. c .., ~)()20. 1 7711.6 4911:?&8 ~>167.4 . :)2!)8 c 9 6~>17 6 4 :i 4 •. ,.,. l . ,),).) c 914?.,1 (,837, i t:·r.·r.• ) ?. ,).),)( .. 9:~BI" 2 Tr··· · a ,),) c r.7 or-. r: ,) .... ,) r. '.W(-J 9 ,) ,. ,) ' 1\B~H, 'J 4629 c 7 . 5428.1 4982.6 4747.? ~)~)0 1, B ~)if,6 d) 4~':~H. 'l 12~HB ,,1) '/,~() 1 • c) 4 74?.. =~ ,.,. r:·a ~~ ,)/. ,} . t\973.6 458~.1 9442. ~~ 4p•·9 ,. h) c &) 46~i4 ~ 8 5346.7 7869.7 6791.! ~j8fi7'c 1 4~'64' ~~ 4~)87 t 9 ~·~·r• 4 6 ,),),) . 1~444,1 474~), 4 7~''' 0 ·-,) c ,) JtH44c:l 460Sc4 Hao9, ~' .... 2?. a ,) .t •.• 774/.cO. 6968.2 r·Jn" 6 ,) ~ ;(.. 9231.9 7~!07 c 6 4B14c0 ~5632. 0 7!)'1 tl • ,t 1.. l •Hl "l • 1' () 0\l<.Q. , .. t)UG 9033.6 08()(1 t C) B4:~6 c :i 8071t6 6:i?.c> J\; j 406:~ .l 1(t0~)~) c 4 0777.7 a~~<·~;. 4 8969.2 /'J"J'J 0 l 9380.2 11«)04.0 1 ?.4Bk d, 9608.2 fJ274c1 ni60. 9 lldHU, 9 8977. r; 9n>6, o R283,B B685.6 !O?.l'J,~) 972lc/ 9;~()J. 7 9036.6 1059;~. 5 9~)67 t :i 9022cl 8210.7 9070cJ l ~'~J91c 0 'J77e.a SEP a:i01c 0 r.'l.6r:' 5 ,) . ~). 6;i91c 0 ~ •.•. 4 ·~ •. ,).,t , c .,a ~j~i·l~i t 5. 8"1~i7 c fJ 8275.0 .. 72~i4 .1 7'"'-o o .) .) t 7390.3 4B7rh 6 6076.2 7?.H6.0 'J78(l t 0 72'.] ? .. ) ' . ,, 1<•:~81 c 7 6764.1 87~·~ a::: ~>· t\J 7647.6 7674,() 7 4();~ c l 7048.9 785~). 7 a:~2~>. 7 68:~6 c 2 606~) c 3 6BBj.O 727.~.1 782t) c 6 7626c7 702(),() ~'316.0 t ' . . i I r' ! "' . TABLE 8.62: FLOW RELEASE CCFS) AT DEVIL CANYON FOR WATANA/DEVIL CANYON -CASE C OCT HOV DE:C ~IAN FEB MAR APR MAY ,JIJN .JUL AUG S£P 1 6602.4 10756cl 12481.7 1 1!)74 t 6 l08B7.0 SH09,3 74{t~). () 6:~05. 0 6047.5 59n9. ~j 10940.6 8949c8 2 6r.•r:·•s r.· 7c)72, :s 8065.7 744:, .:s ()47!. s 6rm9 ,,> 702,S • ~ 7913 t I) 574~S, ,S ~)71~.:1 l()f),~l) t C) 70W/,1 .h),,.,) 3 6489. 8· l 0226 .l 12~i26. 3 11610.6 lll23.a 9S07c8 '7401.3 ,., (: ·-r.· 74:i9. 4 6:~73. 2 10727.2 B2t~1~1 ,) h).,) 4 6623.0 ll385.9 12:.il8,4 11589.2 1l137.2 9929.7 fH:~4c6 974:~! 6 99lHJ c 3 5760.1 1Mi9/c 0 . 79~5H • 4 5 67~)7. f) 7c>,S9, f) 11/H:~ .4 l !2:19. 0 10'/09 J s UH6U.7 77:s:s. 4 · 9H7 ,s • .q 7 >:n r.· r.·yr·) ~· 9971 )\s l'l~i'J .1 ( • • J ,) • ..~ ,)( . ,) 6 6746.9 7l39e0 l2~)62 .4 11637 c !) 11186,2 1 04f>9. 6 771<• c 2 6/.2? '1. n:~k2. 9 7547 tl .112(\9,6 1<H4:i.6 • • •• c .;J 7 7,~?.9JH 1!•)12,4 1247H.7 l i f.)b,S. 9 lf)07(. t 9 H99 J. • (, 7470.1 991)1). ~i 11)f)i'9 t :~ 921 f). ~j 11'699) 7 !649~).8 8 8217.2 11397.6 12~).27 0 7 1160~) i 1 11167.2 1 o:i64 , o 8742.8 7279,6 9(,70 c 7 ~)9~H ./ 10B49c2 B401c8 9 10205.5 11-485.2 12775.0 ll6~!~.3 11113.1 10:i20.3 9:~69. a 7~'!)7 ( 4 7940c7 5B6!'io2 10679•8 B7:~a, a 10 6708.1 707'?.9 8039.7 986~.0 111~)84 9 9()1/t2 7722.7 8638.5 6640c4 6~J:~9 c B 10197.7 13012.6 11 9042.6 11349.7 :12561.2 11646.1 11168 c :J 1 o·J·-~· :1 B/74 •. o 92~)'3 c B "7'-6 ·~ 6024.0 10476,1 7719 t'9 ' ,) \) . \) ,) ... 1?. 6r.·a,~ r.· J.orio7, 2 126~9.3 J. J. H 0 ~i • U 11292.4 l 04:S:f, J. 9rH 4 ,H 9~)71), 9 1 )2"'4 r.• 7147,:s l J. 1)6 c\ • 4 8A 1lH.6 \),•Jt,) I • ,) , ,) 13 6617.2 9907.0 12559.6 11 ~>97. 4 11147c6 1()3!)3. 0 910Bc4 6~'()4 c 7 10407' 7• P1 'J2 r.· 1l,?.2~J ( =~ 14767,2 I , C ,) 14 9289.6 11228.8 l2476oS l1ri92.5 llloa.v 10~H4, 7 831:s.6 n)78. 7 98()8 c 2 ~~~~78 c () 1 1<»5() t ~. llOOB .:1 15 8980.2 :11309.2 12491.8.11568,9 j 1125. ~j fHW3t 1 72~''}. 3 5739.9 10f141.6 a:ii12. 2 1114:>, B 8569.0 16 ·6758. B 90~1.7 124~i7. 0 11566.,., 10808.6 I 9006c 2 7917.2 704~~ .1 76~~4. :~ nj4(1, 4 10669.3 9ft?8.7 17 9478.4 111:~1 "s 12~i:s,s .1 J.lt,J.7,(, 111.ao~o 9u:m. 1 H2t.l,9 ,S206, 0 1 o:~9!i. H 60!)6. 7 1041 «1 "s 8394.3 lfl 6612.1 7070.6 B036.4 9r.55.7 11241-J.l 922Bc4 7/. "'6 r 9(1/.'4 c 1 964() c :> Ul '>2 ,. 12B64cS 15728.2 ,.) . ,, ,_ .. \.} 19 7rib7.2 ll273. !:i 12611.8 l16?1.B 11179.6 l038B.7 9:~99. 6 94'. 4 t' 9988.1 8922cH 10920 c ~i 8709.9 ,) . ,) 20 6593.b 70~)5. 6 7998.0 8·1o::s. 6 j083B.8 8919c:i 7561~H ~)~'BB o 5 5991.7 5682' (1 1117f1.('t 8712d) 21 6663.6 714:{,0 B140c1 7540.0 6554.6 6689.2 6!i44. 4 6(H~7, 6 644&.9 6:~24 c 6 101172 c 8 8622. !) 22 6972. :-s 7:{99. !:i H?.H!i .o no:~. 9 ast,:s. !i 6()86 I 7 r.·~~r.·4 ~ 62.c}A}. H ,S79(,. 2 ro ~~12. o 1040!) t 9 9248.8 ~l\ ,) • ' 23 8518.9 11304.0 12564.7 1l665t0 11214.5 10417.7 9414 ( :J 1(12(,/, B 1 o:H 9." 84(18 c !i 11 :~6~ c 1 8/B4c2 24 626~1 l a 10'/:H ,9 124,s:-s. 9 11 r.·r.·9 ·s 111Al2t7 fJAHJ~.:i 7r.·ay r.· r.• 6'1') ~~ Mi71, :1 ria or>, a J.l UJH .1 B9ri<.. o .,.),) ' ' ,) . ,) ~) \ ' ... ' 25 6!i78,B 7043.8 8003.9 ;~~92. 6 6426.2 8067. ~~ 7t'f·'1 '9 9't''6 .. 6(Jl7.8 5796.9 l:l 037. {) 84~!0 t 1 ,) ,, • c •I C .l 26 6617.7 7119 t !i a1r52, <. 7"''')7 7 6~iMJ, 9 (,(,9(). :-s r.·ur··s 2 817:~ t 9 '191~). 0 H9t)~), ,\ 1 f)94 1 t 6 8144.7 ,, '· . ,) ,). .. 27 7791.9 11076.8 12"!)9 c 1 11:i62 • B 10Rft6.0 B91~4, r> '7B64c0 6'·7rr. 2 64~4.8 f>7~\(, G 6 l1ti9/c7 8BH2c3 ,) ',) . 28 6679.B 7257.3 B235.9 7r.36.0 6538.8 9075.6 8112.6 tl71 ~)' 4 10229.7 84~'9. 0 111~U .2 8~)76.1 29 6722.0 10985.1 j2590.6 1164 9. !) j1197c4 1 0~~91.1 . 9388.6 6729cH r.•s•79 r· 57?l .• 3 j 09:i6 t !) B/73.4 ,) ,) . ,) 30 678;,.9 7228.4 8140.7 7489,2 6!)04. 2 6~182 .a 7;i lfJ. :l 79B6c2 7t,o:>, ;' H!585. 9 1064/)t 7 8702.4 31 66B~i, 2 HB91,a !2r.'1?. r.· 11!)90. 6 1114?..6 1o:m1. a 92(J f. r: 62:~H, 7 9481.9 'l HHJ,?. J.! ?.:S6, 0 8~{6 (.. 0 . ,) . ' ~) . ) .. ,, 32 7855.0 11345,7 124!)8 .o 11592,9 111~1.6 10:J:U c 1 886-'1c9 6'•( 0 In :>5~'B • () 817/,. 9 17878,2 1271,'). f 0 ,, ) ' c .> • ill& TABLE 8.63: WATER APPROPRIATIONS WITHIN ONE MILe OF THE SUSITNA RIVER A 00 IT f{fW\L SOI.RCI:. LOCATION* NU~ER TYPE (DEPTH) AMJUNT CERTIFICATE T 19N R!lol 45156 Single-family dwelling well {1) 650 gpd general crops same source n .5 ac-ft/yr T25N R~ 43981 Single-family dwelling well (90 ft) 500 gpd T26N R!l'l 78895 Slngle-famtly dwelling well (20 ft) 500 gpd 200540 Grade school well (27 ft) 910 gpd 209233 Fire station well (34 ft) 500 gpd T27N R:W 200180 Single-family dwelling unnamed stream 200 gpd Lawn & garden Irrigation same source 100 gpd 200515 Single-family dwell tng unnamed lake 500 gpd 206633 Single-family dwelling unnamed lake 75 gpd 206930 S t ng I e-fam t I y d we I I l ng unnamed lake 250 gpd 206931 Single-family dwelling unnamed lake 250 gpd 'I I ( PERMIT 206929 General crops unnamed creek 1 ac-ft/yr I ·-. -· T30N R.l<l 206735 Sing le-fami I y dwelling unnamed stream 250 gpd ' ' PENDING 209866 Single-family dwelling Sherman Creek 75 gpd Lawn & garden Irrigation same source 50 gpd *All locations are wtthln the Seward Msridia~ \" .~ l. ~:. DAYS OF USE 365 91 365 365 334 365 365 153 365 365. 365 -· 365 153 365 365 183 .. ' ' ·~ 411 I • I '1 TABLE Be64: TURBINE OPERATING CONDITIONS Watana Maximum net head 728 feet t-1 t n i mum net head 604 feet Design head 680 feet Rated head 680 feet Turbine flow at rated head, cfs 3550 cfs Turbine efflclency at design head 91% Turblne-generatlng rating at rated head 186,500 kW I Devil Canyon 600 feet 542 feet 575 feet 575 feet 3800 cfs 91% 168,000 kW .. •.., • . .... ll TABLE 8.65: HISTORICAL ANNU'\L GROWTH RATES OF ELECTRlC UTILITY SALES 1' Anchorage and Fairbanks Period u.s. Areas r 1940 -1950 8. S% 20. 5% .. , .. t 950 -1960 8.. 7% 1~ 3% I 1960 -1970 7. 3$ 12.. 9$ 1970 -1978 4. 6% 11. 7% 1970 ... ~ 973 6. 7f, 13. 1% 1973 -1978 3. 5% 10. 9f, '1._, • .5;1( 1940 -197G 7. 3% 15.2% ,lt.;;_,p !l ~g;;t TABLE 8.66: ANNU4.L GROWTH RATES IN UTILITY CUSTOMERS AND CONSUMPTION PER CUSTOMER Greater Anchorage_ Greater Fairbanks u.s. Customers Consumption per Customers Consumpt ton per Customers Consumption per (Thousands> Customer (MWh) <Thousands> Customer (MWh) (MIIIllons) Customer (MWh) Residential 1965 27 6.4 6.2 4.8 57. 6 4.9 1978 77 1 Q, 9 17. 5 lU 2 77;. 8 8.8 Annua I Growth Rata <%> 8.4 4..2 6.0 6.0 ? .. 3 4.6 Commercial 1965 4.0 1. 3 7. 4 t: .. b 1n 2 2.9 ~ 1 Annua I Growth Rate C%> 7. 5 6.4 1. 6 l I ' I I t ! ,• l .,.,~ 4' I !I ( i i ! l • I v L .. • t·· \ ! t t - ' t f :r " t : t ' i ! t : l t TABLE B.67: UTILITY SALES BY RA!LBELT REG!ONS ~reater Anchorage ~reater Fairbanks ~lennal len-9aldez 1 1 Sales No. of Sales No. of Sales Reg tonal Customers Reg tonal Customers -Regional Year GWh Share (Thousands) GWh Share <Thousands) GWh Share 1965 369 78% 31. 0 98 21% 9.5 6 1% 1966 415 32. 2 108 9.6 W\ 1967 461 34.4 66 N'\ N'\ 1968 5!9 39.2 141 1 a. 8 ~ 1969 587 42.8 170 11. 6 No\ 1970 684 75% 4ei 9 213 24% 12. 6 9 1% 1971 797 49. 5 251 13. 1 10 1972 906 54. 1 26Z n. s 6 1973 1010 5ei 1 290 13.9 11 1974 1086 61. 8 322 15. 5 14 1975 1270 75% 66. 1 413 24% 16. 2 24 1% 1976 1463 71. 2 423 17.9 33 1977 1603 81. 1 447 20.0 42 1978 1747 79'f, 87. 2 432 19% 20. 4 38 2% Annual Growth 12. 7% a. 2'f, 12. 1% 6. 1% 13. 9% NOTES: (1) Includes residential and commercial users only, but not miscellaneous users. Source: Federal Energy Regulatory Coomtss to~, Powsr System Statement. NA. : Not Ava II ab I e. 1 No. of Customers (Thousands) .6 ~ NA. N'\ N\ • 8 • 9 • 4 1. 0 1. 3 1. 9 2.2 4 1 2.0 9. 7% .. U Ra I I be It i' ota I 1 Sales ~ .. of Customers GWh (Thousands) 473 41. 1 523 41. 8 527 34. 4 661 30. 0 758 54.4 907 60. 3 1059 63. 5 1174 68. 0 1311 71. 0 1422 78. 6 1707 84.2 1920 91. 3 2092 103. 2 2217 109. 6 12. 6% 7. 8% • • . ~ TABLE B.68: SUMMARY 0~ ISER RAILBELT ELECTRICITY PROJECTIONS Uttlit~ Sales to All Consuming Sectors (GWh) MES"'GM 1 Year 1980 1985 1990 \995 2000 2005 2010 LES-GL l Bound 2390 2798 3041 3640 4468 4912 5442 Average Annual Growth Rate <%> 1980-1990 2. 44 1990-2000 :3.92 2000-2010 1. 99 1980-2010 2.78 NOTES: MES-GM LES-GM (Base Case) 2390 2390 2921 3171 3236 3599 3976 4601 5101 5730 5617 6742 6179 7952 3. 08 4. 18 4. 66 4.. 76 1. 94 3.. 33 3.22 4.09 Lower Bound = Estimates for LES-GL Upper Bound = Est I mates for HES-G1 LES = Low Econom lc Growth MES =Medium Economic Growth HES = HIgh EconrJffi lc Growth GL = Low Gover·nment Expenditure GM • Moderat~ Government Expenditure GH =High ~Jvernment Expenditure with Price I uduced ShIft 2390 3171 3599 4617 6525 8219 10142 4. 18 6. 13 4. 51 4.94 (1) Reslhlts generated by Acres, all others by ISER. HES-GM 2390 3561 4282 5789 7192 9177 11736 5. 00 5. 32 5. 02 5.45 HF.S-G1 Bound 2390 3'707 4443 6317 8010 10596 14009 5. 40 5. 07 5. 75 6. 07 Military Net Generation (GWh) MES-GM (Base Case) 334 334 334 334 334 334 334 0.0 0.0 0.0 o.o LES-GM 414 414 414 414 414 414 414 0.0 0.0 0.0 o.o Sal f-Supptled lndustr~ Net Genera+ton (GWh) MES-GM (Base Case) 414 571 571 571 571 571 571 3, 27 0.0 0.0 1. 08 MES=GM with Price Induced Sh 1ft 414 571 571 571 571 57\ 571 3. 27 0.0 0.0 1. 08 HES-GM 414 847 981 981 981 981 981 9.0 0.0 0.0 2 .. 92 ( I I \, . I· I j • .. ' /' '. iABLE 8.69: FORECAST TOTAL GENERATION AND PEAK LOADS -TOTAL RAILBELT REGlON 1 is!:R Cow <CEs'"GML ISER Medium (MES-GM) ISER Hlgh::JHES-GM>: Year 1978 1980 1985 1990 1995 2000 2005 2010 Percent Growth/Yr. 1978-2010 NOTES: Generation (GWh) 3323 3522 4141 4503 5331 6599 7188 7522 2. 71 Peak load (MW) 606 643 757 824 977 1210 1319 1435 Peak <1eneratlon load Generation <GWhl <MW) (GWh) 3323 606 3323 3522 643 4135 4429 808 5528 4922 898 6336 6050 1105 8013 7327 1341 9598 8471 1551 11843 9838 1600 14730 3. 45 3. 46 4. 76 (1) loci udes net generation from mllltary and sat f-supplled Industry sources. (2) AI t forecasts assum& moderate government expenditure. Peak load (MtO 606 753 995 1146 1456 1750 2158 2683 4. 76 .. ·~ fl :1 ~ .. J Year 1980 1985 1990 1995 2000 2005 2010 TABU: Bo 70: lSER 1980 RA ILBELT REGION L~D AND ENERGY FORtr.ASTS ~ED FOR GENERATION PLANNING STUDIES FOR DEVELOPMENT SELECTION LOAD CASE Low PI us Load Management and Low Medium High Conservation 1 (LES-GL >2 CMES-GM>3 (HES-GH >4 (LES-GL Adjusted) load LOad Load MW GWh Factor MW GWh Factor MW GWh Factor MW GWh 510 2790 62. 5 510 2790 62.4 510 2790 62.4 510 279J 560 3090 62.8 sao-· 3160 62.4 650. 3570 62.6 -695.. 3860 ___ 620 3430 6~2 640 3505 62.4 735 4030 62.6 920 5090 685 3810 63. 5 795 4350 62.3 945 5170 62. 5 1295 7120 755 4240 63.8 950 5210 62.3 1175 6430 62,4 1670 9170 835 4690 64. 1 1045 5700 62.2 1380 7530 62.3 2285 12540 920 5200 64.4 1140 6220 62.2 1635 8940 62.4 2900 15930 _J lO~d. Factor 62.4 " 63. 4 63. 1 62.8 62.6 62.6 62. 7 Notes: (1) LES-GL: low economic growth/tow government expenditure with load management and conservat 1 on .. (2) LES-GL: low economic growth/low government expenditur~ (3) MES~: Medium economic growth/moderate government expenditure .. (4) HES-GH: High economic growth/high government expenditur~ ( 5) Excludes reserve requirements. Energy figures are for net generation. • .. j 1 I I [ . . . . . . .. . ..... . . ,-:;_ . . . ,: ... . . . . . . . . . . ';..: . '. ~ . -. . . . .. ~ . !ABLE B. 71: CECEMBER 1981 BATIELLE PNL RAI LBELT REGI0N LOI\D AND ENERGY FORECASTS USED FOR. GENERAIION PLANNING SIUDlES L 0 AD CASE f:iedlum [ow High load load load Year MW GWh Factor MW GWh Factor MW GWh Factor 1981 574 2893 57.5 568 2853 57.3 598 3053 58.3 1985 687 3431 57. 8 642 3234 57. 5 794 4231 60. 8 1990 892 4456 57.0 802 3999 56.9 1098 5703 59.3 1995 983 4922 57. 1 849 4240 54 0 1248 6464 59. 1 2000 1084 5469 57.4 921 4641 57.4 1439 7457 59. 0 2005 1270 6428 57. 8 1066 5358 51o 4 1769 9148 59. 0 2010 1537 7791 57.9 1245 6303 57.8 2165 11,435 60.3 Average Annual Growth Rate<%> 1981-1990 !iO 4.9 3.9 3.8 7. 0 42 1990-2000 40 3.1 1.4 1.5 2.7 2.7 2001-2010 3.6 3.6 3. 1 3. 1 4.2 4.4 1981-2010 3. 5 3..5 2.7 2.8 4. 5 4.6 Note: Excludes reserve .requirements. Energy figures are for net generatt~n. • • TABLE Be72: BATTELLE DEMAND FORECASTS--TOTAL RAILBELT High Conservation and Base Plan Renewable Resource Use Medium Economic Scenario Medium Seasonal Scenario Peak Sa las Peak Sates Year (P.1W) CGWh) (MW) (GWh) 1980 521 2551 521 2551 1985 647 3160 577 2746 1990 924 4482 832 3937 1995 996 4894 966 4692 2000 955 4728 936 4576 2005 1073 5327 1038 5085 2010 1347 6685 1245 6101 Low Economlc Scenario Low Econom lc Scenario Peak Sales Peak Sales Year CMW) CGWh) (MW) CGWh) 1980 522 2554 522 25.54 1985 626 3052 557 2651 1990 841 4083 751 3554 1995 854 4150 816 3922 2000 767 3756 750 3627 2005 812 3991 796 3859 2010 991 4878 979 4758 High Economic Scenario HIgh Economic Scenario Peak Sales Peak Sales Year (MW) CGWh) (MW) (GWh) - 1980 521 2550 521 2550 1985 657 3259 596 2835 1990 1102 5639 1002 5043 .. 1995 1198 6168 1164 5937 2000 1174 6092 1148 5888 2005 1391 7175 1352 6892 2010 i88S 9627 1816 9156 ] J J J LOCATION MAP LEGEND PROPOSED DAM SITES ' ' . . • "' ... \ . LOCATION MAP FIGURE B.t lBtR I , • LA ... B • - b.EGlND TYONE" & DAN!iiTE OAMSITES PROPOSED BY OTHERS .FIGURE 8.2 lim\ PREVIOUS STUDIES AND FIELD RECONNAISSANCE 12DAM SITES GOLD CREEK DEVIL CANYON HIGH DEVIL CAN'10N DEVIL CREEK WATANA SUSITNA m VEE MACLAREN DENAU BUTTE CREEK TYONE SCREEN ------ ENGINE,ERING COMPUTER MODELS TO DETERMINE LEAST COST DAM COMBINATIONS. LAYOUT AND t---------~ COST STUDIES 7DAM SITES 3 BASIC ·DEVELOP· MENT PLANS CR~TERIA DEVIL CANYON ~BJECTIVE WATANA I DEVIL ECONOMICS HIGH DEVIL ECONOMIC CANYON ENVIRONMENTAL CANYO~ ___ __. HIGH DEVIL ALTERNATIVE ~~~~N~ m CANYON I VEE - SITES . HIGH DEVIL ENERGY VEE CANYON I WATANA CONTRIBUTION MACLAREN '---------' DENALI ADDITIONAL SITES PORTAGE CREEK DATA ON DIFFERENT THERMAL ·GENERATING SOURCE;.;:S ____ ...-____, CRITERIA COMPUTER MODELS TO EVALUATE •· -POWER AND ENERGY YIELDS -SYSTEMWIDE ECONOMICS ECONOMIC ENVIRONMENTAL SOCIAL WATANA/DEVIL CANYON PLUS Tf-ERMA.L ENERGY CONTRIBUTION LEGEND DIS. HIGH DEVJL CANYON DIS WATANA ~STEP NUMBER IN STANDARD PROCESS (APPENDIX A) SUSITNA BASIN PLAN· FORMU~ATION ·AND SELECTION PROCESS FIGURE B.3 ~~R I • II . ft;; t PCftTAGE CR. 100 ·. 120 140 180 RIVER MILES • . D~a» F4 <( 19P&'-~ 205o! ~ ·2200' OSHETNA RIVER r---=-:..-..1 2000' F ==T • tr;;00;rvoNE RIYEPI I I I I ! __,--4' -MACLAREN RIVER I·· _jJ 2200' I I I I I I 'I ~ 23501 ! 280 1_soo• PROFILE THROUGH ALTERNATIVE SITES F\GURE 8.4 " • GOC'D DEVIL HIGH DEVIL CREEK OLSON CANYON OEVIL C~EEK CANYON GOlD CREEK ;:;: ::::: OLSON :;::: ::: ,• :;;;: ::::: n :::::::~:::: DEVIL. CANYON HIGH DEVIL CANYON DEVIL. CREEK LEGEND COMPATIBLE ALTERNATIVES :::: ;;;;. ;;;.; :;:~ ;;::;;;.;:: ·~~ a·. F.:l .::l ::::: r.::: WATANA SUSITNA m ·- WATANA SUSITNAm ~EE MACLAREN :;;.~~::::::::::::: ~=mt~mm· !~~: . ; :::;)~\~[ ~~· ,, ~::;;;:::;:=~::: :;::•::::::: :~:~ ~~: ;:~: :j:~:~: VEE D MACLAREN MUTUALLY EXCLUSIVE ALTERNATIVES DAM IN COLUMN IS MUTUALLY EXCLUSIVE IF FULL m·:·=·~·~i:~~~~·SUPPLY LEVEL OF DAM IN ROW EXCEEDS THIS VALUE-f'T. I :: VAI.UE IN BRACKET REFERS TO APPROXIMATE DAM HEIGHT. DENALI BUTTE CREEK l MUTUALLY EXCLUSIVE DEVELOPMENT· ALTERNATIVES ! ·-·- BUTTE DENALI CREEK TYONE I FIGURE B,!5 • .. .. .................. ~ .......................................... ._ .... r~~----.w ~.r--~._._._ \:;j Ul u. z z \100 0 ~ 1000 ~ '100 J Ul e.oo .£XCAV'A.ii0N / EXISTING GROUND StJRF,b..C.E PROFILE. E.XISTt""G ;a::x::..::, J..EV£1. ;l-__..~...t---'~ "'"' -...t---L-1 _....___.. _ _,___ ... , -=:::-. !0:::::0 15CO '20CO ..,.AGE. •N F'e.l!.T QOFILE. FIGURE 8.6 [.~ ". ~~ ),.___ALA_SKA ___ ro_W_E_R_. A_U_T_HO_R_IT_Y---1 M [j sustTHA HYtlRO£~£CllltC ri\OJECT DEVIL CANYON HYDRO DEVELOPMENT FILL DAM "",.. OEC 1961 I I ·-------,- ·:.oo r--~-­ ·400 !;; l:' ·!>O:l ~ il.oO ~~~00 ~ ·~oo z Q JQO !,( ~ l:xJO ""=>o I·--------- 0 J ~ \:t··ila.NtFO~o .:._GA-!. Sf1A;-"" 15CXl '< FE."-i Pk'Ot:'ILE. ;::cAC!LlTIES r~· l ~ I l ( ' I 1 ! J -~· ,... r . ·' . ·~ L -· SE~~R~L ~~~~~~~~~ s.:.o..-e.. A. 7 0 "100 ~ > Ill .J Ill SF~c i' .:::lN 1-·A. 'L-~·c . ~RM.t..L. .... A" W 1.. E.L '2.2.00 """"""' -:, -~~---'~-----·~- 0 r !>CAt-£. '!> 0 ~L.E. c. 'P= SC.CTION TI-IRU DAM SCAI-E.'P.> sao ~00 too __, JCOQ FEE:! rmiPiil .400 FEET -7.00 n.E:T ----·--.-- 5PlLLNAY PROFIL£ SCA.W:. 8 FIGURE 8.7 ~ A...AS.c..A ;;ewER AU"ll-lOQ:ry ~ '!t-s. -.... r.. -:¥5'<cc.£.c"!"::c.c "~:Ec:r WA'ANA HYDRO OEVE!..O?MENT FILl. DAM r r : 1 l '.: ~ " 'j w ::.oo '50:l &00 ~::>0 :;oc .. -·-~·- --~~AGE.Jl SP .• ~WAr."r ..... ----------... _o•JG:T:..JOI"-.t:..L SECT;QN Tl-H2;.; t-OF DAM ~":.Ai...E €;; ... ~ .. :'~t-..AA .. MAlt .O::.PERA.,. NG ..,£,J"£t..,..E .. 2'2X' SPILLWA.Y ~C:AI...E · e. PROFILE. ti!900 It ~ IBOO ~ 1100 .:; ~ J<iOO Ul ul ·500 1400 5EC..,..ION Tl-li<J.J D~ SC:.~L..E.;f!, POWER FACILITIES PROF"ILE SCALE' B seA!.& A ~ 4 a I"'E.ET J.tXJ FEET .$C/>.1.& f!>~ 8.8 ALASKA POWER AUTHORITY IUIITtrfA t4YDft0lLlCTRtC WATANA STAGED FILL DAM Pf\OJlCt 12 8.5 8 I I ::1; " -<:x: :; o-::oG> ~ o:r "' • 0 01'1 % m< .. <-0 "'r ,. ro 0 .. 0)> ~ "l>z .. 1:-< " mo ~ zz ,. -i " ~ ,. 0 .. n ~ l_ r {) z ~~ ~ <:.. q .t; f./~ (I! t') ·-1 6 z. -l r fi) c D .., ~ ~ ~ t-E..Vb~ li"')r" ·•J Cf:E.T ~ ?\ H ~: -·~-Ji-t; n. .J • ·rrrr : i 1 r:1lt ' ' ' ' ··1 ' ! l i II 1 ~lh~ ! I l I 1.' I ·~. :vr ' •·' ; ''I :t l I "' k' f. ' i r,· ~ '{ I r,l· , :.; , • fll"' I• ' I " 1 r· :r J; f · ~ t ii ~ y! M 1~' I Y'l• p I ; 1 ~ l , i '1\. ,. 1 J,t. : • n' "' I ' .11 1 I '~ ~ , i nl ~· IU ! 1/t. n, 't ]:u., t• I• .I I v•t l,i :; I . \ . ,, 1, ! ~~ $: I '[!II Il l ~ ~ ! I ! I . l/ I 1:~ IJ I 1/: j' i ; /l ·I' I I L~~r 1 1 ,,t·r !' / I . v . l ,·,~, ~! ·. -~- :: f • rl' '\,, ' i ' .~ .., .'.:1::= .:; .' 'I 1; +t •• ,, .. ·~ {; L ' c."!. q "" ~. r ----·'i !" ·----;. 3J It .. ' (.h :· ... f· l'' •' •{I ·11 ~~· I I>' ··~ "' 11\tP ""' 'lift nr b I~ I~ "' ELEVATION IN FE.IiT 8§8§~8§§ I I I ' ' I , ,,. ' ; ' 1: f, ~ ~ ~ I j ·~f·····- j : r AI ~ 1 I , , • f'J 01-I , i... ~~ 1/fi~f ~ l> §~I r I ... 8 rL ~ !>-~~~~§ !;; ~ •. 1J 2: i)l~ i J o;:: ::!!!'] r _, 1 § " m -n c; c ::u rn >I!D s; ID .., ~ ~I .. 8 "' > c .... :z: 0 "' ~ i I 1 Ef'l/ lz-•lh l l -~ ~ ~ '1 : "I r ~ ; po\,i ~ 2~~ j~~1 ~~c: : !i ~; :r:n -~.,.. !( ~~ )!1 f.l! I I ' (t ·~ r g I~ ,: IJ i i~ ~ \} () ~ § [!I fJ r]l ~ n ~ r () "' r {jl --1 •. 0 m J:_ \PH ~ ~I 0 -'TJ z -" r m "'~~ n ~ ~i n; ~~ I ! I ! G) rn z [II ~ i:l: ~ ~) iU )> J> 7 6) [II :;: tTl i!: -1 [ ·-::::::1 p.::;;;:;:;;;. ~ i 1'!:1.-EVATION ..... FEET' n: ,..o " ri .Lg~ I} -~ I' '"' I I~ I f;_ : r i I~ yl =:1:-:.t-..:-~~ 'I !:ol-:::1::-r~ -- 1 ~~ ~ K' i ~ !'i 2: " " 8 t 7 0 II' c ;;J ~ rn j \ 'i l I (/) [ll () II' -1 ;'I -~0 ~z {jl ·-1 r 1J c 0 l> ~ 1<>''1<""'•'-''ii' It-~~ ~ 1j:;:':;1~ l ~ ,~ I / lj_jf) 1t ' ) J (j / :-.; .. . ~~--.·1' .~ l \ \( f l I J . / / I I EL.5:VATION IN F'EI!.T § ,/I . ' I I ' i i J ~ p ~ ~ ~ ~ r ~· r- t ~ o. ...J ... . ~ I I t \l' ' ·' . ' -1($. -1· ~ ·I I . (J ' o'\ ~. (;o \::::!.r:· ;) 1/ /,.., .. / / /f .__./ r =·--·--· J """"-~.-~ .... ~---~------:---·-~--·-----.. --.. -,...,. _________ ...., Jo.;:'i<Mf.~..o.fi.A>t. #L.. jc .... i~' ,---------~~-"=~-?-~" 17'-\'~~:------ 1900 1------------·---~--- 1800 -------------· liOO 0 S!:..C1•0N '71-lR.ll DAM $\!.C.I..E,.: e. t I •! //-:.,.J~f..~A...,...;. GA.l:..LE~ -· ---,·'*"--.. -~~11--L------1--.P,..-=,----.::.;:;_::.;.;._ I / POWE.k. FACILITE.S PROFiLE. ~·.:.A ... e. e 10 G14A..ll·•.:..GE. .N rE.E.T ?PILLVVAY PROFiLE.. 1!:> FIGURE B.IO SUSITNA m HYDRO DEVELOPMENT \ ,_,._,...._ ... ----- \ '2t.OO 2._!00 m .... 00 u. ! ~ ~ ~ cl ·1000 '(~A--tAAJt; ;_~': .. · ~o;_-:_:-~_:=rr*r---:-.."'---==---....::~.-.-----;--...... ; .. .,,:;_,___ ~~:-~ .. 4,.~;j ........ tt __ .... u !: FOL LENG· 8.5 8 r_•_ t L f I L 1 J [ f f L. fl ! l 'I ~1 l J d ,, --r· ~ .. ~ ....... . ·<'-C b------------- 1~~ .! '~ X. ;____,_ --~~--- "~"------.... '···-·· --------·----------~-~--~/~~~~~~-~-~~-~~~~~lLL~-~-~~~~~~~~~--: ,..,,, ..... i".'<;'~~··r-f •· ... " f ......... ~ '-..'- tr... ,......_....._--.... --.. .. _ ._.r..... '-., ___ } ~ .. 4 .!..CLA~E.h..l SE.""S~A.'-A~<:~~ .. ~:· .. ~E. .. "T : ~:... .. : ;-..., ;:...:...~..,, !~RO!:.S· ~E.CT1.JN ~:...t...~.-c *'i)~t..\A~ t-.A,tU; ·-,..;·. "ao. :o.i'is • \ DENA:_! GE...,E.RA.L ARl<.ANGE.ME.t-. T SCALE·A ;....~R¥<!.. ... "~AX '"'"': ~~a~ ts.~~· · l ~ .. u ~~/ / ··---.__ :~<:oss s~::c-:-;o:-. e.::A~e: e, OO..i!OLE. B£l.LMC~~._. r-r<.:.<:~:..t.r:.~ ONI..E."f ~----'-.... f-J•; ....... F'O'<AR'f o:>a<tO:.G ~ :..=-:. "0<:1. PovE.tl.5oO>. ......_ __ ·~ , ·· ~-. -L.\: 2.· ~'2' .. :.'2-~C.Ot-.:A,.! ~ .. '4. ''"' ~ ~7.' "\'t-JE..E.L.. MOUNiE.O Gb.iE.~ S E.C710N D·D --------- FIGURE 8.12 I ul~ IJ--ALA=-·=-sKA-:-::::-:Po::-:w:-:-E:-:R::A-:-:U-;-T-;Ho;;-;;R:-:-:IT-;:;Y:-1 fti [j lUStTNA HTDIIIDtlltlfliiC rAOHC'1 DENALI a MACLAREN HYDRO DEVELOPMENTS 22·.00 FT. WATANA 800 MW -~-2 MILES . --1475 fT. ~~ ~,..--RE-REGULATION DAM • 2 EL5 38 FT. DIAMETER 800 MW-70MW 2 TUNNELS 38 FT. DIAMETER DEVIL CANYON 550 MW H50 MW I!IM----RE • REGULATION DAM 30 MW 30 FT. DIAMETER 800 MW 365 MW 24 FT. DIAMETER SCHEMATIC REPRESENTATION OF CONCEPTUAL TUNNEL SCHEMES 6 TUNNEL SCHEME # I . 2. ~3. 4. .. • FIGURE 8.13 ~~~~ J J l SC+-lE.ME. ~ ~--- ··--·---·-------, ·--------·~ PLta.N GENERAL AR~ANGEME.NT DEVIL Ct..tJYQN Cb'tv2R~OUSE !>CAI.E 0 400 FEET E:::: GENERAL. A!;?RA~.;GEMEN'T [___------------------------------------------------~-G __ ~~ __ :~~~::~U=L=:=~~o~,O~:N::~~-·~--~=EE===T============~==============::======;:==========::~;:;:~;;~~==:.:~;=======::·~··~~;::::=:::==::: AI.L "'L.A.NS 'WO ...AV.:>c1T$ FOQ. CONC:CJ:"TuA.~... S,.;JO'( "'-'""""'$~ Or<L.'< f..-;J ALASKA POWER AUTHORITY 00!!1 IUtlfllfA H't'OII:OJLIC"f';i"C '"O.ItCT PREFERRED TUNNEL SCHEME 3 PLAN VIEWS ••oo f ,,OQ lLOI1 ~ ~ f ?:. ·~oo % ~ ~ w 1'100 J ( .. 1100 i tt I~OC ,_ . .. "l!C ?:. :z 0 ;::: 1400 ~ ,. w J ... '-00 ~"'e l l ISQO I ~ .. ! .. .._ ' : 1400 % 0 ~ ·!OC ~ ·~CO (f ----~--~:~---·~----~~~~~0~c·~~JL~~~~~L_-~---~~~~~~~ -~ •. ,.-.• , ___..,.i.:. -------------· ~-------- .. ; :1 ) r7 RE·REGULATtON DAM TYPICAL SECTION I®Or------------ ACC<.S~ r-T-"""-"-~oo' l -11-!tt-:::7.='---r-~~t-- POWER' TUNNEL INTAKE SECTION ~CA-E. A.. SP!LLWAf ;::;ROFILE >#00 1500 E ... :; llOO % 0 s ''lGQ ~ .... ... ... __ ._ POWER•~ --~--~-~--~--~ ----------~---~ .. 6----·-L----~----~----~---~---~~--~----~-----L----~.o~--~----~---------------------------------------....... ------------.... TUNNEL. ALIGNMENT '~ ' \ ' DEVIL CANYON POWER FACILITIES PROFILE ~~~~--~--~S~C~A~~~~~A~- NCT~.' i ft-.... · {; J"'""''"VI! ! (-... ~Uo.$U ·:~,\ ! __ , .# .,/ t'/. DE.TAIL A AI..~ ~·~~,tc,-~~~ .:.:,:; S...:F:~":" :::.ETA LoS A~ :.:.,~,., .. E.~TttAL. t..NO to:o~ sr ... :~v j:: ~"~~~e.~~'-"' ;t:•A!L A I"NPI -I l>ETAIL& (1TPJ ROCK BOLTS , ROCK BOLlS 4 SHOTCRETE l / FA$:,"T ~!"T'rl~ .. 'lt.OUT TYPICAL TUNNEL SECTIONS {>.C<". T<;l !:>C:AL.E) SIEiA.IL'c FIGURE B.l5 PREFERRED TUNNEl. SCiiEME 3 SECTIONS ~--~---~-~,~~~~---~----~<~---.. -·---~..._-..,_---~-------... ~---------~~-:v-. ,-~~·~~~t ·",.?;~-;-, ,:-,-~--.~!~4~,:-·;;, .~ ·-:c":7~:~'"'·c"':"'=.,.._,-....,...--7"":---~--;--~-~·.-·-,.--··-.._~.............___.._. ..... ,~--..,,""' ... ___ ,__ "" J l 0 s: ::!:2 0 0 0 10 8 :I: 3=6 (.!) 0 0 0 >-(!) ffi4 z w 2 ISSO 1990 LEGEND~ D HYDROELECTRIC -COAL FIRED THERMAL ~ GAS FIRED THERMAL 2000 • OIL FIRED THERMAL( NOT SHOWN ON ENERGY DIAGRAM NOTE : RESULTS OBTAINED FROM OGPS RUN L8J9 TOTAL DISPATCHED ENERGY • DEVIL CANYON (400 MW) WATANA-l ( 400 MW) EXISTiNG 6 COMMITTED 0~--~----------------------·----------------~--------------------~ 2010 1980 1990 ~000 T~ME GENERATION SCENARIO WITH SUSITNA .PLAN E 1.3 -MEDIUM LOAD FORECAST- FIGURE 8.16 . 1 :) r~ r·~ 1 j J ;: :!: 2 0 0 0 '~ ':r.- 0 <t:t 0. <( 0 10 8 :I: ~6 0 0 0 2 715 1980 1990 LEGEND: D HYDROELECTRIC li~fJjf~~ COAL FIRED THERMAL EZ1 GAS fiRED THERMAL • 22!0 2000 2010 • OIL FIRED THERMAL( NOT SHOWN ON ENERGY DIAGRAM OGPS RUN L601 TOTAL DISPATCHED VEE(400MW) ENERGY HIGH DEVIL CANYON-2 (400MW) HIGH DEVIL CANYON ·1(400 MW) .. • EXISTJNG AND COMMITTED 0~---L---------------------------~------~--------------------------~· 1980 1990 2000 2010 TIME GENERATION SCENARIO WITH SUSITNA PLAN E 2.3 . r;.~ .·1 -MEDIUM LOAD FORECAST-FIGURE 9.17 •• - .. br.: ' L. .f~ ' .3 ~ :E2 0 0 0 I >-t- 0 ~· <l u 10 8 I ;=6 (!) 0 0 0 I >- C) 0::: t\1 4 z w 2 715 LEGEND= D HYDROELECTRIC MIJ COAL , .. IRED THERMAL f.Zl GAS F~REO THERMAL • OIL FIRED THERMAL (NOT SHOWN ON ENERGY OIAGR NOTE : RESULTS OBTAINED FROM OGPS RUN L607 TOTAL DISPATCHED ENERGY TUNNEL{380 MW), . ANA-2 (400MW WATANA-I( 400 MW) ~. EXISTING a COMMITTED 0~--.. ~------------------------------------------------------------~ 1980 199C'J 2000 2010 TIME li- ----GE_N_E_R-AT-Io_N_s .. _c_E_NA_R_·'o_w_'_TH_s_us_r1-·N_A-PLA·--N-E3_._~ __ _uUB._I~. R_,. !JIIi -MEDIUM LOAD FORECAST-. FIGtiRE 8.18 ·I I ; . ! 1'1_.· !4: 'I l"'-1 r~~ ~I. [~ . r .;.--,· .; [ i_, .. · !;. .... [J- -\00 X '* - 7300 72.00 7100 ~ 7000 (/) 0 0 z 0 i= 0 :::> Q ~ 6900 a. :I: J- £1': 0 :r;. t-saoo z w (/) w £1': a. 6700 6600 . 1----· ~. • .. 6500 2140 2160 ~ ~ . 2180 2200 DAM CREST ELEVATION WATA NA RESERVOIR I 2220 (FEET) I I / .. I - 2240 2260 DAM CREST ELEVATION I PRESENT \'10RTH OF PRODUCTION COSTS·· ~-~-"-· FIGURE B,l9 •• ......____..,..__. ·----_.,..,.--------------~--------.:::::====-a .. r--"'t ...----. .----. ....----. ,----, __.... .--~ ·r-~~ \'~ ~1~-~ rr-:-_; fr2:·~·4\ fl:::~:_! ~~ ~-2400--.......____ ------noo -----·~~ rr~-~ r.-~ ·~l ~e ITf'::'",..-':-; Tt:-~:;;; ';"-. .. . -•'*-II': ".1 .llfi.....,.LJ l n :.:.,.,~--' ~ ' I ~- CLO~uR£ EMBANKMENT EL2UO SWITCHYARD ARF. A 1 tJ'I'l'l'flfJ) ,/·(I NOTE ~\\i'fl rT'PJ...:..-·-. ~ ,~'-. THIS DRAWING I~LUSTRATES A fo,/'( ' ,._<¢ PRELIMINARY CONCtPTUAL PRt'.;(CT L~YOUT «'}' · ' PREPARED FOR COMPAniSOH OF ALTERNATIVE -' g '-"" SITE DEVELOPMENTS ONLY .. ... uoo r. ----:-, ,}' ..... ::! ~ .~· ·-· ·- 0 200 400 FEET SCALE~ too_./ FIGURE 8.20 ALASKA POWER AUTHORITY -·sustrNA HYoooEiTcriitc ffi'Qj£c::r· WATANA ARCH DAM ALTERNATIVE £1:'2.......---.... Ac;[;,;;r;uCAN'1Nc(;PO~Allo· MARCH 19e2 .. .. ........--, t.F .. ·. ~ ~ ..... --'l .........---. ...---,__ .... -. ~,·~ tF~-I !:p-..-! ~~~.~~:~ ~~~~ ~-..~~--1 ~--'tf:'-' • ~ ' t ' i [ _,, I ""·-""·-~ " -·--~ 113215,000 • - ,r-- .----. --·~;~::.;' z---:1 ,...--, 'it:::...,.,,., ~:~ .. '"' ~· ~ • --, ----. ~ i--· 1...-..... L.-.2.2 Be \LE } 2f0 :r FEET FIGURE 8.21 ALASKA POWER AUTHORITY SUSITNA H'!'llflOELECTRIC PROJECT WATANA ALTERNATIVE DAM AXES MARCH 1982 I t I I I· • • ! I~ I I J [] [i ft [i r d f :· L. l L,. l L. [L I L~ (; ~M o!-·~~ (1 L.- r b L .. U L~-.._. 1600 I \ \ \ \ \ (') \ LESS THAN 3~ I ENTRANCE SUBMERGED -1550~-------+--------~--~~4-~---------r--------~ .,; ll--z 0 !« > w _. w 0 TYPICAL TUNNEL SECTION 1450L----------L---------L---------L---------~------~ 25 30 35 40 45 TUNNEL DIAMETER (FT.) NOTE FOR 80,000 CF S WATANA DIVERSION HEADWATER ELEVATION I TUNNEL DIAMETER FIGURE 8.22 • .. I f8 w~ ~ ~ fti [1 (~. (i [iii (~ [~ r~ \._. [II [! ~ ~ I} t~- t--=- LL z 0 -~ <( > I.LI _, IJJ 1650 r-------.-----r--~r------r-------. AT 1720 COST 50XI06 IGOOr-----H~---r-----~---~ 1550 1---t--~-t------r-------+---------J 1500 '------..~..... ____ '---___ __,_ ___ , IOXJ06 20XJ0 6 30XJ06 CAPITAL COST $ WATANA DIVERSION UPSTREAM COFFERDAM COSTS 40XJ06 FIGURE 8.23 • ,. j .. rJ G fJ [~ [~ [~ f t~~- Gt [J. Lii [~ [~ l~ lJJ L~ [} IJ I • 80--------~---------.--------~--------~------~--------~ -50 U) 0 - X -- ..... C/) 40 0 0 -' ct 1--a.. <! 0 30 20r.--------+-------~~-------+--------~--------+-------~ 10~-------+--------~--------+---------~-------+--------~ 0 TYPICAL TUNNEL SECTION 15 20 25 30 35 TUNNEL DIAMETER (t:T.) WATANA DIVERSION TUNNEL COST I TUNNEL DIAMETER 40 45 FIGURE 8.24 • .. l I r · r· r l] f~i ft [I n [I L_ L .. l { . [ L .. t L,~ l t 11 L L~·· f~ L ~ l~ U L. tJ !:c- • .-----------------------------.--. . .,_._. ---------, ,-. U) 0 - ')( - (f) ... (I) 0 (.' ..J 4:l ... 0.. ~ 0 ..J ~ ... 0 .... 1oo -------.--------.----------~-T 80 70 60 0 TYPIC At. TUNNEL SECTION 50 15 20 25 30 35 TUNNEL DIAMETER (FT.) WATANA DIVERSION TOTAL COST I TUNNEL DIAMETER 40 FIGURE 8.25 m .. • .... --. r; "I c;:-~ i ~ ,--......, ,.---... r~ Ll: ;-.,.'""""- r----.. r;--'1 r-' ,...-.., r-r--, l~~ 1,,, 1i T 7 •' ,:<"' ........ -0,#<. ·, \ / ALT£RNAYIVE 3 -r---. , ............... /!-r-......., ... l ;---'! l ALTERNATIVE 2 AL'fERNATIVE 2C AL"TE.RNATIVE 4 WATANA PRELIMINARY SCHEMES ~ ~ ALTERNATIVE 2A ALTERNATIV~ 20 FIGURE 8.26 ~~~.l[tl ALASKA POWER AUTHORITY j\.1 IJ SUSiTNA HYDROELECTRIC PROJECT WATANA PRELIMINARY SCHEMES MARCH 1982 \! i • • • -~--r;--t ~~ ' Lr-·i.e:-,...._ ~ r-----> ~ r-lf"!''-~ l ----tlWO -----tuo • ~ Lt......... r-,_.... ~. ,---- ~JL. ,...._.... .,._ l,.t ... -- 21200 FIGURE 8.2.7 ALASKA POWER AUTHORITY IIR SUSITNA HYDROELECTRic PROJECT WATANA SCHEME WPI PLAN MARCH 1982 L .. It "~~'"'"~ t i.e- '- noo IUO 2150 1050 tooo 1100 ::. .. so ... ... ;: ~I tOO .. ~. ITDO 17,0 111!10 1100 15!10 I 1500 r 14!10 ~ 1400 l uso ~uoo I ~ ~21!10 ~ tiOO L~~.2 r;--" ..---..., ,---...... ..--.. ~., ~4--•L. I~ ~ ~ r-----·--l. / CONTROL STRUCTURE 3-S~'W&~O'H fiXED WHEEL UUS --ORIGINAL GROUND~---· S-SD'W a40'H FIXED-. ---· WIIUL GAUl ~-· --·-· SECTION A-A SCALE A ~ Jl; ~ t r-, .k>~<-~"-""" SPILLWAY PROf'll.E Sc'i:'L£i. --ORIGINAL GROUND ~----· _ _.... ---- l:j 2.000 "' ... % ;; 11150 0 ~ ~ i0il900 [ BE~I!OCI< ~ SURFACE r:: t SECTION SCALE A 22'0 .. ... ::! 22.00 ~ , 0 ;:: ~ 21!10 ... .J ... 210:1 ! 1 r j o-o r l;c i:: d 1~00 SECTION 8-B SCt.LE A SECTION E·C SCALE A >-i!200 ... ::! -lrililiiii!Hi: TYPICAL CHUTE WALL SECTION s:ALE B .l ~1!1!10 ti ~ FIGURE 8.28 "'21CO .~ SECTION c-Q SCALE A L THIS PR~WINO IL\.US~RATES A PRELIMitlAIIY C.OUCEPiUAI. PROJECT LA'IOUT PREPARED fOR COMPARISON OF ALTERNATIVE !liTE DEVELOPMEtllS ONL'I t. atllTIOHS FOR SCHEME WPI ARE BIMILA!I EXCEPT THAT GATE STRUCTURE IS "o' Willi! WITH cREST EL 2150 AIID 3·401 WIDE X 53'HI0t. OATES GIR ALASKA POWER AUTHORI'fY suslrNA HvoRci'Et:EC:rmc f.RojEcr' ~ · ·· WATANA SCHEME WP3 SECTIONS MARGH 1982 • • 21TS s------ GENERAL ARRANGEMENT SCALE!A • 0 200 400 FEET 3CALE A. ~!!!!!!~~OiibiOii~ 0 ~0 100 FE£T SCALE B NOTE -THIS DRAWING ILLUSTRATES A PRELIMINAR't CONCEPTUAL PROJECT LAVOUT PREPARED FOR COMPARISON or. ALTtRNATIVt !ITI!: DEVELOPMENTS ONLY SECTION A-A SCALE :8 FIGURE 8.29 I j ALASKA POWER AUTHORITY SUSITNA HYOP.OELECTR1C PROJECT WATANA SCI-IEME WP 2 a WP :5 PLAN a SECTIONS ! ! • • [r~~ ,..._..,., r-----. r:--" ,,--.....-. . ~-. iT-ur-t[r- uoo 22:00 j SECTION A-A -,_ rr-.Jr==" SECTION 8·8 ......___. ~"'-'"""'"-"' 1000 l!Tii.TIONIHO li'l FEET r----'1 :r="": IJPILl.WAY PRO~ ,,..._..., ,.....__., .i'f"'"-=·" ~-=-:.:' eoo r 01 --...., .----., 'f= F-::.o:- 0 SCALE 2000 IDO 200 rEET THIS ORAWINQ l!.lUS':II~S A PllEUioiiiiAII'l' CONCEPTIJAL PROJECT LAYOUT PIIEPAIIED tOR COiolPARf.l()H OF ALTEIINATIVE t"T£ DEVEL(11'M£1m! ONU' ;-I 1 f--··-1 r·, ...... , -~--~-~~~-- 21!00 FIGURE 8.30 ALASKA POWER AUHlORITY SUSITNA HYOflOa.EcT~IC PRO.:'<'CT WATANA SCHEME WP2 SECTIONS -----------.'IC.IU AWt~ICAH IHCCMolll.T£0 MARCH 1982 ' I I • . • --~""2zso~·~ ,..,.-· --_./' THIS DRAWING ILLUSTRATES A PIIELIMIN4RT CONCEPTUAl., PfiUJECT LAYOUT PREPARED ron ClliiPAIIISON OF I.LTtiiNATIVt SITI: ~::<tLOPidtHTS ONL\' ----~------_.------------~----~---------------------------------------·----""---------w---------------~.~------~----------------- IT~O I 'rOO~-·--" 11,0 1800 '· 1580 __ , ---~·"-... FIGURE 8.31 .,1 ~ ALAS:SA POWER AUTHORITY 1\1 (j n---s'"'"u"'s""ITN""A~H"""Y""DR-O"'E"""LE-CT-RICPRO.iEc:r-··- WATANA SCHEME WP4 PLAN MARCH 1962 • • . (1:- tl w ,.. J: ~ ;:: ~ ~ ., ... w 1:! ~ r 0 ;:: ~ ~ ... ... lf',; w--_____.., .,.__..., -""' ..,.._--...... -, ~t~"' ' p ____,.., __., .................... :::-1 .--.--1 .~ .----"'"""' l~-t.r--~,r--~ iJ --'t~ :_.,,:-c f"""' r~r r·~ . . ' L --'·-~ l::-r ~ ~: ~::: IIORMAI.. MAX. 'Ill.. CONTROl STRUCTURE EI..:ZZOCl (SEE EIILA1'16ED DETAIL) .-------------+--------,---1------------------------------------------------------·------------------· t-100 DOO. _ : ~ --·--·---~£15' OVEJI~Il£N -··«--·--· ·--.... ----·--~-·--· uoo 11\'0 !000 1900 !100 I TOO 11100 1!100 HOO !HO me 2100 -=-~----------·--·-----· ~------------fASr.ADE ------.. --------------------------~=-.. --....__ __ ::">... ··= = : <::::::::. ~ ----.:::.."'; -·----~--t-BEDilOQ( SURFACE ..:;_______ --~ LEFT $IDE ----------·----.!.~.-...::-=::;---~ ---··-· ~·~-::-... ····--------·-- --------· -·--· . .. • ..,L_ 'S:~-' -·-....::. ORioiNA£:oliO'lr•r.)"""iiRFACE ••• , •·-....::,-;-...._ ' '-.._LEFT 8£t;£ ···-----·-··--··---------------~-~ ·-----'----c:~~~EiifiOc~ SURFACE -~ '"" • ...:..'.....:.:_-~-·-- -. ....---- ,__.. ------- ··-· ----·----------------1:--------------z I -,~-_~HT •. CIDE_, __ , .:_..,_, --"'*-·~·· ... 1-------+----------------------· EXCAVATIOH-AIOHT SlOt:/ 1 '). • ..:::-"£0RIGIIII.L CROUND~s:hu"""'""'"~~ l_ ___ . ' ·RIGHT SIOC r----------------~~-----------------+------------------------------------------------------------------------------------------~~~------------~~~~ L ••• ·:~;:-.._ '------------------------------s~~~--~~~o--~~~--~~s--~~~~~~,o~~~--'---'---,~e--'---'--~--'--~zo~~~-J--~~e~~-~--'---'--,,~o~~--'--~--'--~35~~~-J--~~~~-'--~--'--~~~~s--L-.t...~~--~so~ ! 'ATIONifolO IN FEET J+.B SPILLWAY CONTROL STRUCTURE SCALE! B • SPILLWA "!....E.B.QE!!4 SCALEI A ELZZZI~------------------------- SECTION B·B SCALE! B ------------------- ~ ~ uool----- z ~ ~~~--------~!--~-~.+-~~--~=====iJ-~~-1~--t-~--~~~~------------------~~.1~=~ ~ II w I I I I -------------------------------------~~~··--------1100 '----------+--- 1 FIGURE 8.32 t"-~ SECTION A-A SCALE! I SECTION C-C ~CALI!I li 0 200 40(1 FEET crc.u A ~~· ~~5iiiiiiiiuiiliil •• 1W ALASKA POWER AUTHORITY fl (lll---SU--SI-TNA...,-H,...YOROEl.-....,..-EC-l-R1-C-I'""'RO:--J""ECT,..,---t o so too FI!I!T ICH.I! ll (11'1 Sil-lii .!!2!! THI9 DIIAWIHG UlltTIIATU 4 llfii!LINIIIAI!Y COftei!I'TUAL I'IIMCT LAYOUT I'MAUIED FOil COfoii>AIIISOH Of' ALT!.ftti.'\TIVf lilT! Dt:VtLOI'IIIENTS 0!1\.Y WATANA SCHEME WP4 SF.CT!ONS MARCH 1982 -------------·· --------------------------~------------------------------------------·/--------------~--------------------~----------------------------·---------~--~~~ft~l~I~A~M(~ft~IU~N-I~NC~~~~-~~~~---~··------~----~ l r7: ~I rr: ~. ;----, -___., ,.-.... It~ 1 !;.:: l ----.., Lf"'""' 1.;-r~~ Pt' 'f i-f~· . t"~w ' c • ---, .....__.., ---.1 r~'1 ,___,.., .. ...,.,.._,., -· ,,, ........ r~ ~~ ~ r·-I ~ I H. ~~. ,_ 200 40° FEET FIGURE 8.33 ~-~[p ALASKA POWER AUTHORITY ~2200 .... t=ftl:-=(l=.. ___ su_s_IT_N_A_H_Y_OR_O_E_L_E_cT_R_.IC_PR_o_J_ECT ___ - 1 .~ THIS DIIAWIN<J ILLUSTRATES A PRELIMINARY CONCEPTUAl. PROJECT LAYotrr PREPARED fOR COMPARISON Of ALTERNATIVE SitE D!VfLOPMENTI oNLY WATANA SCHEME WPM MARCH 1992. ____ .._ _______ _ ACNU AllfMICAH INCOI1P0MlT[O .. ' # ~-­ \ ' IIGO--~--- THI9 OMWiNO f~LU9TR.o\TES A PIIE~IMINAifl' CONCEPTU~ PP PIIEPAIIEO FOR COMPARISON ;Jf.CT UM>UT .\LTEIIIIATIVE SIT! DEvt.LOPhtt:NTS ONLV ~po ~IX> -Fm FIGURE 8.34 ALASKA POWER AUTHORITY SUSITNA HYDROELECTRIC PROJECT WATANA SCHEME WP4A t.:[.;.<-J~ &cit!A'Wt'ittiii'iiiciiiiPC,ft'ATio MARCH 1982 I' 'I L I ! • .. l r t [ ( I I . \ l j ~ """" """'· "'= 1~50 ~------~---------r--------.---------~ 1000 ........ -----+------++-----r---------+-----1 ·-.,.: u. -~ ~ ~ -1 Ill IIi u : u: :') (I) ffi 950 I -PRESSURE TUNNEL (361000 CFS i 0 880 TYP. TUNNEL SECTION 20 25 30 35 TUNNEL DIAMETER (FT) DEVIL CANYON DIVERSION HEADWATER ELEVATION/TUNNEL DIAMETER 40 FIGURE 8.35 \ • : "L;_·: ----· I I . I 1 j I 2Q 18 . 16 14 -U)o -l-en 0 0 10 8 6 0 TYPICAL TUNNEL SECTION 0 - .. - \ ~ ~ v ~ • 25 30 35 TUNNEL DiAMETER (FT.) DEVlL .CAN 'ION 01VERSlON TOTAL COST I TUNNEL DiAMETER · · 40 FIGURE 6.36 • .. .. .. ~~ "' r--~ r--:-:-"'""'1 •'' r f ~---. r---"r r-' 0 0 7 1 \ \ ,...._.., ,.....---. ,...--~~ -,.._, r----' ,.._ -... ~ r.--"'t -t~ r-' _.._,..., • .... I. r:-=l. r.-::::l. ~ '---::-:-::! '-.::1 ~ 1'1~,~~., .-----. _......,.., --~ ......----': ,........._.., __, ,.........-, --r-'1 ~ rr-""'1. __ _, ' 1&00 ) ) 1400 I l I J ) 1300 \ ~ 8 !2 .. I SECTION A-A (-- \ , I I ' ' GENERAL ARRANGEMENT SWITCH YARD /EL. 11170 I \ ' ' 0 100 &CALl!~ ' \ I I I I THIS ll!IAWIHO ILLUSTRATES A PRWMIHARY CONCEPTUAL PROJECT I.AVWT Ptii!I'Afl!D ,OR COMPARISON 01 ALTI!ANATIVI! BIT! DI!VELOPM!tiTB OHI.Y POWI!RHOU ;E LOCATION S'JQJECT TO OPTIIIIZATIDH STUDIES Of' OOWH3TREiol LOCATIOfiS, FIGURE 8.37 IIR ALASKA POWER AUTHORITY 11--=~~--~ SUSITNA HYDROELECTRIC PROJECT DEVIL CANYON SCHEME DCI --~--AtRtn AUIRICAH INCOAI'OI!~TlO MARCH 196Z l l l I l ! l l \ I I I \ I (' • ·~ -r""~ .,..--, ,.....---""\ ,-"---... -"' r-~ r~ ~ r-"' ,., , .. -'"'l r---'1 t . I i.; ·I\ I '' ( / I l \I \\ 'I \ \ 1\ \., \ \I 0 \ g \\ ,, \ ..... --~ r \\ .t It I t ',1 \ \\ ~~-Ulltl.flL ... j ,, % \ \\ r----1 -~ ,, " ........ ~<(~i' \ \\ 0 0 ACOUI T N[L~ s \ I\ ' 0 : ~ \hi\, \ \\ 1\\ 0 \ ~~~ \~ 0 \\ \i~~ ~ \\ \ ( g \1 oog .. \\ ~-I -1\ 0 I \\ ' 0 ( \\ I !:! 11 \\ \ ,, ,, ,, ~ \ II \\ \I '· \ ~ . " \ ' \ \ r---'"'1 ~ r-' ,..__, ·~ ~ j ( ~0 ) ... / 0 "' ~ I I I \ \ \ ' ' ' ' ' ' ,, r ~· I I I I SIVITCHYARO \ I I El..l370 i ' \ \ ..... , I I / r I ... .,..,.,.-""\, \ \ \ ' \ \ ~ . co,. ... ·., SCAlE GENERAL ARRANGEMENT \ 0 " \ \ I ' ' I \ 0 0 !2 \ 0 ~ \ \ \ I \_,_ \ ' \ 100 200 l'l:ET ~ TillS ORAVIING I!.LUSliUI t tJoO A PfiW!jiiW'IV CO!iC!PT.JAI, l'fiOJECT LAYOUT PM .... MO FOil COMI'Afti!ON 01' ALT!I!IIATIVE liT! I)(VEL~NTI Ollll' ~ POWERHOUSE l.l)CATION SUBJECT TO OPTIMIZATION STUOlES OF OOWHSTREAM LOCATIONS. -FIGURE 8.38 BIR ALASKA POWER AUTHORITY 11-----------l SUSITNA HYDROELECTRIC PROJECT DEVIL CANYON SCHEME OC2 ~ MARCH 1982 ------------ACRES AII(RICAN IMC~f'CIUfEO \ \ • 1P ... :.; ... ... !': t 0 .~ > ... ... .. 1n .. ur.e • • lee<! "00 ~ 1:500 !tOO 1100 1000 100 800 <40' SECTION 9,.9 liCA~ 8 \ <4d ' GENERAL ARRANGEMENT SCAU::A -~ ... _.... ------------·---.. ---· \ ·- SECTION C·C SCAtl;t II ... E SECTION A-A SC~L.t!: A ~ ------~·--··---- ·-------------- G ~ ... ____ -:-;;&;;;-TW;--------'-.,_ ,JMAX. T.I'I.L. ' , EL. 928 EL. 921l EL. 8]8'-..._ ·~ ¥ ==f MIN. TW.L. EL.II72 f ~ ~~--------- SECTION D·D SCALi!l I 0 SCAI.!! A I GO 200 FEET 0 20 <40 FEET &CAL!: D c:2::=~s=a==J~-- !!Q.!! TillS OIIAWIIIQ ILLUSTftATE$ A l'llfl.IMIH.<II't COMCEI'TUAL 1"11MCT LA'IUJT l'llti'Mm 1"011 COIIII'I'IIIaotf Of' ALTtAMATM: lin lliVti.OI'illKTI OIIU' --. ~:='::~ SECTION E-E acAU::II SECTIOJLF·F SCALE: II SECTION G·G SCALE: ! FIGURE 8.39 lml ALASKA POWER AUTHOR~TY ftdlj 11---:S~~=::::-A:-:-:H'r:::OROEL.ECTR=;:::-;:=;:IC::-;:PR:;;O;-;J;:::ECT=---t DEVIL CANYON SCHEME OC3 ~~ itiiii.Wfii~iiic'i.;o;".Ti'o MARCH 1962 • .. ..--- 1.. ' ~­) OEMEP.Ai.. ARR~NG~MENT -t---·----g:::;=cr.:.·==..;-....;:;-~~-=--=:-:-_ .. :l____ ----------··--·-------------~ 100 200 ~00 400 DOO 800 70o 900 g(,o 1000 1100 IZ\10 doo 1~00 u!oo uioo ri'oo 0 1100 ..---~------ ti 1:! 1000 1----- SECTION 8·8 SECTION IE-E. S7!1TIONII'" IN I'E!T !!ECTION A-A ( TlliiU !PILLWA'i'l SECTION C·C SECTION F-t:_ oo:(!.. T1'111 DIIMitt.IQ IWJITIIATtl A P'l![l.lllltiiNtY COI!CEI'T\IAL l'ti0J!C1' U\'I'OUT I'!11UM£O POfl C~lltltllll f/1' II.Til!IIIITM IITI D£V[l.l)f'WliTI tw' SECTION D-0 0 100 200 FEET SCALE t=== F!GURE 8.40 IR ALASK4 POWER_ AUTHORITY SUS!TNA HYOROEl.£CTRIC 1'1\0JECT DEVIL CANYON SCHEME DC4 • "o "o I I J I I ) I I \ \ ) ~ 8WI7CHY~AO f.£L.I'5TO] ~ 1 \ \ \~· ~ ~ ~ . , \ ! I \ ) { ... I . 0 100 200 I':!ET ) SCALE I W -=;;;;? ..... _,.J NOTE Tl«< DIIAWIMI IU,III't!IATU A I'ML .. INAIIY COMCII'TII4L PIIO.IICT U'I'WT ,.,.l'I\Mtl 1'011 coti,_IIIIOfll ot' ALTIIINATIV!t IITI MWLOI'Mt:ll T ottLY. I I I / I \ \ I ( \ ~ I \ \ I I I I ) '~) ( I ~ { 1 b ~ \ --- "-··-··-~·-·-· ··•••'\" ---· . .----~~ '· ~\ -~ ~\ FIGURE 8.41 ALASKA POWER AUTHORITY SUSITNA tiYOROE\.ECTRIC PROJECT DEVIL CANYON SELECTED SCHEME MARCH 1962 i l \ l I I \ I l· r· I 1 I .. ... ·"""" . ,, . CORRIDOR .. SCAI.E a MILES "-:=--b: --rl ' ' L ACCESS PLAN ~ 3 [NORTH) ·''SUSITNA HYDROELECTRIC PRO.JECT AL TERlNA TIVE ·ACCESS PLAN''· • • FIGURE 8.43 • .. • • ". ~-"~~~-·---'--··--------~-.-., ... ,.,..~., ... ~,..,--------~-"--·-"'· --···--·------······-····--~·~ ------------~~--~-'--~--.. ------'----~/ ""-·~~----'---"--'~------- ACCESS PLAN ., 6 [SOUTH] .,, SUSITNA HVDROELIECTRIC PROJECT ALTERNATIVE ACCESS PLAN,, FIGURE 8,44 [j] .. .. i .. ACCESS PLAN 'I' B [PROPOSED] ~ "SUSITNA HYDROeLECTRIC PROJECT ALTERNATIVE ACCESS PLAN'':- • • FIGURE. B.45 OJ . ' ' '.: ". . (}' .. . .. ' . . ~ ~' . . ' . ~ .. (\ l • • ~: t . $ ""' .. ' " . ...... ' . ~ ~ ~ g • • ... • ... ... •• • ' . . ~ . ~.. .. .• . . \ . SCHEDULE fOR ACCESS AND DIVERSION 1985 1986 I I . I • TIME FRAME FOR EXPECTED '"~~ ISSUE OF FERC LICENCE IVERS ION CONSTRUCTION nmm (I) 1 0 I I NITIAL ACCESS CONSTRUCTION 1 ACCESS REQUIRED DENALI II 11111111111111111111111 · NO LATER THAN (I) ~ . I THIS DATE TO I SUPPORT DIVERSION CONSTRUCTION ~ NORTH lHTTmTIIIlllll ( I) l I ) THTTIII SOUTH -· . (I) ·• . • RIVER DIVERSION v ·~ II I I I • I :. 1 • I I I I J I 1. • I I I I ·! NOTES: 111111111111111 ACTIVITY START COULD BE DELAYED AND DIVERSION STILL MET. ( l) LATEST START DATE OF CONSTRUCTION ACTIVITY. """ I L ~ [iiJ FIGURE 8.46 t - .. . .. .. ' . . . .. • \ l • • ' I ,< ' • I f ,, r L " ~,. ..... h ' !:~~--;.;;, i·, : ALTERNATIVE TRANSMISSION LINE CORR~DORS SOUTHERN STUDY AREA LOCATION IIAP LEGEND ---STUDY CORRIDOR •••••••••••••• INTERTIE ( APPROXIMATE ) 0 5 10 e ; iiiii SCALE IN MILES FIGURE 8.471•1 F:OLC lENGl 112 ) 1~ i • IB.5i 1 13 r l I -l I _! J ~·:~ r ~A.~~~~JM~~~~_:~ l ·---------·----·--·------------------------------T-=---r==:::-:;:~:1 ® @ l N / ALTERNATIVE TRANSMISSION LINE CORRIDOflS CENTRAL STUDY AREA _../' LOCATI:JN MAP LEGEND ---STUDY CORRIDOR ••••••••••••• • INTERTIE (APPROXIMATE) 0 5 10 SCALE IN MIL.ES FIGURE 8.48 f r· 1: I ~ I ~ I ® I I I [I LOCATION IAAP LEGEND ,_--STUDY CORRIDOR •••••••••••••• INTERTIE (APPROXIMATE} 0 5 10 :e:::: .... w I SCALE IN M 1 LES ALTERNATIVE TRANSMISSION LINE CORRIDORS ~~~~ NORTHERN STUDY AREA FIGURE 9.49 U ----------------------------------------~--~ r t I I ; L [":,. i. ! l u i ® \ •,...;a f \ \ i ! r~ \ \ . \~~\ ~.> \ {l \ . \ i }I ~ \ ~ ~ t I I I ~ ----- 0 I ......,._....., ~CAL~ IN MILES RECOMMENDED TRANSMISSION CORRIDOR SOUTHERN STUDY AREA . II 2 J i.OCATION MAP FIGURE ,! I 1 r i l L,., ,..., j' J n il u LOCATION M4P J 0 I 2 I s;;; Ul SCALE IN MILES RECOMMENDED TRANSMISSION CORRIDOR L----------------~--------------------·---------SOUTHERN STUDY AREA FIGURE 8.51 r t li f . r ' !1 It L. r: L r I l -' 1 J .::::! fl -.I J l @ n' j r !)1·-:~:_-~-:_p~~~~~~~~~~~mf\lrJf+J~~h~rn~~~x?7iHc?t~"l1' I.--·~~~~~~~~~~~~~~~ I MATCHLINE B RECOMMENDED TRANSMISSION CORRIDOR CENTRAL STUDY AREA ll 0 SCALE IN MILES 2 .. "' = 5C.&I.£1NMILES LOCATION MAP FIGURE B.5J •I .. ~- /'' / 12 ·-·---·--··---~------.c-:-~----~~--:..::::::::::::_.~-----------··f! ___ :_:_:::_~..:::_:_:...::;;.:.:.:_:_: __ ~~:J.~~-·"-' - .... RECOMMENDED TRANSMISSION CORRIDOR CENTRAL STUDY AREA ~~ \ ~· ..... I I I I ; L-c MATCHUNE B] 0 I 2 ~~--=-I SCALE IN MILES 0 .. "" c:s:.= S1CAU 1"1 MII..[S LOCATION MAP I ( RECOMMENDED TRANSMISSION CORRIDOR NORTHERN STUDY AREA MATCHUNE C 0 E SCALE IN MILES 2 I FIGURE I ·. 1 •• DO tcAI.£ IIi MILD · LOCA TlllN YAP \ '... . i' \ ' .. FIGURE 8.55 \BIRI RECOMMENDED TRANSMISSION CORRIDOR . NORTHERN STUDY AREA SCALE IN MILES I ~ 'l J ~-~ J l j J @ ~ I l I I I ~ 'l. -, ; ~ ~ \ ,. -!. •. ); '\ -~ . RECOMMENDED TRANSMISSION CORRIDOR NORTHERN STUDY AREA ..... ~ .... io .... ... ... • : " ' •• I ~ / 0 t' ,.;) = 111C1U: IH UIL£5 LOCATION liAP I 0 I 2 I -==:a SCALE IN MILES FIGURE I I I B.Ji}· rl I l ~ 'I FOUl LENGl 12 · ~I 11 ·;1 s.s·;j 8 ll ll : •urf ·' -~ . l l.l MANU~ .J! l Fee6 r I' L r L L [ J . .. -~> ~ -- '\ i . ....,. ",( . (. RECOMMENDED TRANSMISSION CORRIDOR NORTHERN STUDY AREA ... 0 SCALE IN MILES LJCA TION MAP 2 FIGURE B.5711Rl I l Eh J 12 11 8.5 8 l I I I; I rr I 1.., n ,, L .,.. ,;~ r: r~ r ' L-., L f _\ 0 c 0 ..J ~ • w a.. "' 0 .-z I.LI (,) c:: ILl a.. 100 90 80 70 60 50 40 30 20 I 0 0 0 . ,/ I I ~ v 4 i 8 12 HOURS 16 WINTER WEEI<DAY HOURLY LOAD VARIATION -... ~ '\ \ 20 24 NOTE: PEAK MW DECEMBER ZOOO AD: 1084 MW 100 90 0 eo <1: 0 ..J 70 ~ <1: 60 ILl a.. II-!SO 0 .-40 z w :10 0 c:: w 20 a.. 10 0 1\ _, 0 / ""·-L-'"" "'--. v J I """ f-../ 4 8 - 12 HOURS 16 SUMMER WEEKDAY HOURLY LOAD VARIATION ' I • 20 24 NOTE: PEAK MW JULY 2000 AD: 658 MW til ! TYPICAL. LOAD VARIATION IN ALASKA RAI LBELT SYSTEM • 1100 1000 300 800 ~ 700 ::.E 0 600 <C 0 ..J 500 :Ill: <t ILl 400 a. aoo 200 100 0 /_ " v ~ / ·-' v --..,. - i f-.- - I I I 2 I • J F M A M J J A S 0 N D MONTH LOAD VARIATION IN YEAR 2000 FIGURE 6.58 ] u ( \ • \ cOOt( IN££'T DATA COLLECTION STATIONS ~ """'"------"· Cl'lr. STATION ------·'-~·~ ' IAl -IT* II!Y£II lEAl! llDIAll I ,., ~ lr.YVI AT W:E ~ 11:1 "-88TNA llrV£R ICAII WToUIA ~ i {I)) !Uli!J"!lo\ I!Mll lltfoll DlVIL CAIN'"..fC ; ltl !IUISITllol -loT eDLD C!Wl'.l< i If)~ l'l'm! II[NI ~ I&) m~CU:TJ~A IWWII NEAft ~ 110 SUSfl1ll4 --~ , I I) ~ IIMll NUll !liCWEII1'* l IJl TEIITll4 l'iM:II Nt:AII ~ mnoH IKI 30SI1'* 111"\0 loT IU3IT1CA ITioTlOII ll; X X X X l( )( X X )( ll~Jg X X II )t II X X X r!-x X X X X X I I( X I X )( )( X )( X X X X )( I X X X 'l, il,· "" ., 1:11 t ., . t~ x\x•xj m1-Pft£WCT I ['"•-••n ,·. I tt«l-Pflts.t"f lljX X X IWO•PIIEIENT l X; :x )( ' I I $49-~ X \ \ 19!141-rtn a i 1980-I'IIE!DfT X '""-P'RDOIT l X ' --I'I'IES£NT ·X l ; mv-IMO I IHIO-I'M:l!OfT l l I l IIT4 -o'M:liEIIT __j I I I !2m 1. I"AJJAMETI!M t1!A11U111ED UlJTED II M'PIJeCIC Dl t. ~ w.T!II ..urr ..mill ~ J DA'm COUECTIOII 1111 tiiEMC* 0 10 l!O -.ES .... (APf'IIDll USED IN PMF STUDY [jj] ~~~--~~~~~~~-=~====~~=:=:=:=:=:=:=:=:=:===:=:=:=:=:====~;:==~===:=:=:=:=:=:=:=::==::=~=::==::==::==:=:= FIGURE 8.59 ·--------~---~----~--,r--~----~-~--~. --~--.. -.-~= .. ; .. =.===;:=.;~.~~;~;~;,;~;~;~=~~-~~=.=~=;;~=-=.=-~~~_=,=;~=~=~=~=~=~=~=1~~;~;~=.~:-~.i~-~-~~r-.J_ ·o L [ I CHULITNA RIVER YENTNA ROVER 39 4 ~o SUSITNA RIVER DEVIL WATANA CANYON SITE SrtE :19 °/o · 20°/0 GOLD CREEK I TALKEETNA MVER -go~~~= SO 0 '· PARKS HIGHWAY BRIDGE "' GAGING STATION 0/0 SUSITNA GAGING STATtON AVERAGE ANNUAL FLOW DISTRIBUTION W'fT'HIN THE SUSITNA RIVER BASIN FIGURE 8.60 .. ' ; \ .. } l ' 50,000 LEGEND WETTEST YEAR .. ~962 -0 40,000 z 0 AVERAGE YEAR (..) w .(/) a::: w ~!EST YEAR -1969 a. 1-30,000 w w LL. f..) -(]) :::> (..) -3: 20,000 0 _. LL. ~ <{ w n-: ..... (/) iO,OOO • NOV DEC I APR MAY JUN JUL AUG SEP OCT MONTHLY AVERAGE FLOWS IN THE SUSITNA RIVER AT GOLD CREEK 0 JAN FEB MAR ' FIGURE 8.61 -;-, I 1 ' I I l ' 1 l l G ~' l. "' 0 -"' -(f) u. 0 - LLJ Cl a: <[ :I: 0 U) Q 0.20 0.40 0.60 PROB OF EXCEEDENCE FLOW DURATION CURVE MEAN MONTHLY INFLOW AT WATANA PRE-PROJECT 0.30 • • • 1.00 FIGURE u~ I anm l .. • ----- _, J I .f . !\ .llo! \ ' ·""" ~ t i;,L t ~. ,.,. __ ~ 't w.._. L 48. .. 0 - )C -(/) "-0 - lLl Cb a:: <l ::1: 0 (I) Q .. It I 8. O.D-'------------...------------__,. 1.00 0.40 0.60 0.80 0.00 0.20 PROB OF EXCEEOENCE FLOW DURATION CURVE MEAN MONTHLY INFLOW AT DEVIL CANYON PRE-PROJECT FIGURE 8,63 • • J\ ~i • l' ,, l ' ,, : i l 'l f <:1 ··1. ~. ~ • • • I 15 r O.Ol . -- . - 0.05 OJ 0.2 0.5 I b -- RETURN PERIOD IN YEARS 1.11 ·l25 2 5 10 100 r WATANA PLUS DEVIL CANYON I I ' FIRM ENERGY~ r , . . rWATANA ONLY II ' -"~ .. , 5 10 20 30 40 50 so 10 eo 90 95 98 99 f'ERCENT EXCEEDENCE PROBABILITY FREQUENCY ANALYSIS OF AVERAGE ANNUAL ENERGY FOR SUSITNA DEVELOPMENTS I 1000 . :-- rFIRM ENERGY ' - 99.8 99.9 FIGURE 8.64 f· 99.99 1 I t •I' I. I . f f l L .. J J 10 60 20 10 0 uoa l-...---1.-----L--L---1...--'--~_j 0 s 10 15 zo 25 liO l!!l TIME (DAYS) 1•50 YEAR FLOOC (SUIAIER) --· _, .. , .. ----;----·-.,-----.--·-1-··-r-~ 1 I i 2200 J...---.-..i..---1---+---+----+-l-+-t---1! : l 2198 -219~ ... ~ z ~ ~194 < > ... ... ... "' 2192. 6 > E ... ::l 2190 "" 2188 !!.laG 218'1 ~--~---~----+---~--~,--~~ 0 i ' ----···--" -·"---+---, . . I ' ·-~~-'' -· ' "'UTLET f4CILITJES +-·--j ' fULL C4PACITY ; POW~aiiOUSE AN:> OUTLET FN:ILITIES ~ OPER4TIHG (MATCHIIIG INFLOW) 10 15 20 25 TN£ (DAYS) 1•50 YEAR FLOOD ('UMWER) '50 leO ICO 140 1:0 ; ... u 100 g 2 ~frO ... 60 40 Ill SPILLWAY OPERATIHG POWERHOUSE AHO zo oun.ET FACtLmEl FULL CAIW:ITY POWEIIIlOIISE AMO f OUTLET FACILITIES OPEIIATIHQ (MATCHiliG IHFLOW) 0 0 5 10 15 20 u TlloJE (DAYS) 1•101000 YEAR FLOOO 2202 2200 Zl~ -2196 ... J!, "' 0 ;:: 2194 ~ ... .... "' E 2192 0 > E ... ~ ZIPO ZIBII 2186 218<4 0 15 lO t.~ TIME IDAYSI 1•10,000 YEAR fLOOD --· ~j .~ i J l!O :.!1 MO -· f'--l . t !\>, /"OUT !'\..OW NFLOW"'I u I, I \ I ! \;t\ I llCEWERGEHCY SPLLI*Y\ O!'f;RATING \ \ ( -\ ~' [\ I " li!O zao Z40 ; ... ~200 ~ t 150 ... ... IZO I· /l J~ M.<.IH SPILLWAY OPERATilG ~PO'NERIIOU~ AND OUTLET _/ FACII.ITIES AT FULL CAPACITY TLET F'J.CILITIES \)PERATIN~ 1»0 40 0 0 15 ~0 TIME (DAYS) PROBABLE MAXIMUiol FLOOD ~1'--.. 2200~----~-----~--=-+~~+-~"'~4---~r---~ 11--E".AERGENCY SPILLWAY' O!'f:RAnlO 1\ :::: :~~~~:~~~::-_-.-1----t----Jl-\-\ -_ ---+-+------l-1 I \ I j l \ ~~.' ~ 219~ --r-r· I i :: ~---~-,--~.-~\-~-1\---~---t--+-\ I J or: MAIN SPILLWAY, OUTLET FACILITIES l . ~"'"';"' ll,i ~loe I---l--l'--+-- ____., I 1\-OUTLET FACILITIESI I I nJULLCA~~c_rr_v __ ~----~----L---~ !1840 L-----~~'-----'-10 10 20 25 50 ll5 21111 TlloiE (DAYS) PI\OBABLE MAXIMUM fLOOD Fl GURE 8.65 IAII ALASKA POWER AUPIORITY .. II---:SUSrTNA""'~=-:-:-:H-:YDRio-::-:OEl.-::-:Eo-::.::-::1 :::-:RIC~PftOJ-.,..-:E-:CT::----1 WATANA HYDROLOGICAL DATA SHEET 2 MARCH 1982. <~<-·~----------------------~~ ,__,-'T' '~T' ---T--1 ~~FLCW l "' ·-"'+' F,c •• -~ \rOUTFL.OW -~+ •·'-'-~ \:----r-----1 ' ~ ISO ~'tRHOUSE CLOSED, ...J ... IZO liO J -~-""""-·~ ~-~~---+--~--i PROBABLE MAXIMUM FLOOD IIDERVOIII ELEVATION ; ! .. ~~ ... ~ --~--"' . I l ' ' ' 14l.O -'-----+---:~-~~+-4--!----i 1400 1-----t---t----1r-----Jj,---+---!---l 0 ll 10 IS 20 TlME(MYSl PROBABLE MAXIMUM FLOOD 1110 /""\. 1110 I 1 140 1!0 ;; ... u ~ 100 .:: jr eo 0 it l I) ~~tA:9w • OUTFLO'II~ 1\ I I I '-._ [\ I ............ - 60 40 to l pt;' i '-MA.IN j"'LLWA.Y ?PERA.TIHG ERHOUSE AND ~LET FACI!..ITr OP£!1ArNII 0 0 15 zo 10 TIWE IDAYSI RESERVOIR ROUTING 1•10,000 fR. FLOOO 1460 r--·r-- ~ 1450 \) ~~~·OUTLET f.FUTIES j NO MAIN SI'IU.WI.Y OPCRA.TI I 1\-MA.X. JsEL•Ie5 10 ,. 20 l5 Tlli!E (DAYS) RESERVOIR ROUTING 1•10,000 YR. fLOOD so 20 v 10 0 0 1460 ;: 1'158 IL z ~ > 1456 a 0: §~ ., ... 0: 2 14!:00 J*ffl.IJ ·OOTFLL :; 1'--t t- f'I'OIIERHOOSE IUIO OUTLEY FACiunES OP£1lA.TING \ S 10 ~ lO !5 TillE IDolYS) RESERVOIR ROUTING t•SO YR. SUKIIIER Fl.DOO J \ lr POWERHOUSE J,JD i I OUTLET FACILITIES OPERIITltiG I r I I .. \.~~oA-lWSEL • ~5~ I ! ' ~ 1 i I 20 !5 30 10 15 TillE [OAYSI RESERVOIR ROUTING 1•50 YR. SUWIIER FLOOD FIGURE 8.66 ALASKA POWER AUTHORITY SUSfTM4 HYDROEl..fC'TRIC PROJECT DEVIL CANYON HYDROLOGICAl DATA SHEET 2 MARCH 1982 ' t 2600 ~ 0 6 1~80 I 2500 t 2~00 .• 147:> l l 2300 ---·~·~·-~ ........ -------+-- I ! 1470 2200 j I I E ~ 2100 ;: ... ... ./ v ~ 146!1 ;:: g "' -' .. 1460 ~ ~ 2000 > d 1900 !BOO I L -~-~ I I 't l noo 1600 1455 I' i I_NI7T DEfiHED !500 1400 0 2 6 8 12 14 0 20 VOLUiol£ (ACRE FEET •101 ) RESERVOIR VOLUME AND SURFACE AREA I ! -v / / . / I i/ /i J /.! v I 1 I 'I ! I l I l ' I l ' l I i l ! I ' -~ ! -+' -~r->- ' l t ! 1 I i l l - 40 60 10 100 ~20 CISCHAR6E (CFS • 101 ) TAILWATER RATING / 140 160 120 ., ... <>I~ 8 - E 60 0 . l I 1 I I I ,-; v l /i -I ·.-JIJ. I r, ·- VIi/ I v I / / ~ 7 ~--/ v I // ·-+-~ "" I l i l I I ! I I i I I j_J 1.005 5 to 20 50 100 1000 10,000 RETUR« PERIOO (YEARS) INFLOW FLOOD FREQUENCY FIGURE 8.67 WATANA HYORC:..OGICAL DATA SHEET I MARCH 1982 n 1; i '-l' { 0 -.."""""-'-'--~~~,~~J· ;:: "' "' l!o ~ ~ ...1 1/J' I~ 1'100 1300 1200 1100 1000 900 0 SLV'FAC£ AllEA (1000 ACRES) 12 10 8 I) " 2 ' -.-·<>+--,.---'-------. ...-... ~ __ ..,.. ___ ~_,_,__ "'··~-----""'""""'~- ..... _ _.........,... __ ~_ ---+--__..._._,.,__.,._, __ w_ --+- .. 6 6 10 12 VOLUME !ACRE FEET X ,o• l RESERVOIR VOLUME AND SURFACE AREA 0 810 _.J j 865 i l ___ J I I r ;:: "' U1 ... 1 1-86Q 5 w :I; "' C> <( "' 855 sse 845 14 i ' -·t· ---:--" ·- -l I j +"'-~~--+--~ I . .L I -·1 -1 j +- .I L.__.__~-'--*-~--._ _ ___._---. ·----~--] (' 20 60 eo 100 I :!a 140 160 reo 200 C1SC~ARGE ICFS X IO'l TAILWATER RATING CURVE I!IC IG: -~---~-·-------·--1,--4------l-- 1 i ----~---l-1--l---i--l--·-·--+-1'-1 . I 150 f--- , I 135 -----~--------------t-·--l---+-41,----4--1 111 ... 120 ~ 1Cl5 0 E Ill 90 ~ ~ 0 75 60 IS 0 ....,.._---·~..-. .,._ ___ ~-.-·· ----·u~_..,. . ..,. > .~ ......... ',.,_.,.---r-__..,.--" ' 1 L_ ________________________ .~~----~5--~10~~=-~5~0~10:0--~~~~000 1.005 ~ RETURN PERIOD !YEARS) FLOOD FREQUENCY CURVE !INFLOW AFTER ROUTING THROUGH WATAHAI FIGURE B. 68 I IPD[Q I ALASKA POWER AUTHORITY nun£o 1---s-u-st-rN_A_H_v_oo_o_EL_E_CT_R_i_c_PR_o_J_E_cr __ -l DEVIL CANYON HYDROLOGICAL DATA SHEET I ~ .. ,. ... -MARCH 1982 i'CRE$~tRtCAN iNc.~P.:,RATEo q ,.--~ ..... ----' • 2200[ 2190 NORMAL MAXIMUM ,OPERATING LEVEL 2185 I I 2180 -12180 -2170 ,...: LL. 2160 -2160 -_. 2150 "" > 2140 -l&J _. 12125 2130 0: 0 2120 ~ > a: 2112 lU 0 w 2100 f-a: 2095 2092 J 2080 I l I ; I ._J 0 N ·o "' F M A M "' "' A s MONTHS . WATANA RESERVOIR 1460 r- NORMAl MAXIMUM OPERATING LEVEL 1455 1450 f- ... RESERVOIR IS KEPT FULL AT -r= 1440 ~ ALL TIMES IF POSSIBLE. ll.. L -_. LLI > 1430 f- LLI iL _, a: 0 1420 f- > ' a: ' "' 1.0. •.• en w 1410 ct: - l~ 1400- 1390~---~1 -------~1------~'-----·~----~l--~J _____ ~l~---J~---~J ____ ~J _____ J~----J· 0 N "' F M A "' "' A s MONTHS DEVIL CANYON RESERVOIR MONTHLY TARGET MlNIMUM RESERVOIR LEVELS FIGURE 8.69 .. • "' 740 t 15 °/0 GENERA OR RATED POWER ~ .. , ~t' I ' RESERVOIR EL 2185 I -r-------- 720 I ! ..... 680 I I I . tl WEIGHTED ~ 'ERAGE HEAD 700 \:i t... ·-..... IJJ r UJ 660 ll.. f,.oo~ t 0 <l UJ ::s: l ..... w z 1 7 . ~ INIMUM OECEME ~R HEAD I 640 l ~170 MW I t I I ! 62.0 I I. BEST EFFI< IENC;_; FULL GATE ,, .. I, I RESERVOIR EL. 206!5 -~ --I -- ll " 600 \ t ~ 580 100 12.0 140 160 UN\T OUTPUT -MW 180 2.00 220 WATANA -UNIT OUTPUT fiGURE 6.70 i f j :.., -~ L 0 ->-(,) z LL.I 0 L !A: I&. I.&J ~ I i 4.~ ;:) .... \ h., L l ' L l l 90 80 70 40,000 ~· \ _.:_. \ _':'l:.:· ~. ~ ' .. ..., . . \ . . . • • ... " • .s. aopoo • ~ ... e. .. 120poo 160,000 200,000 TURBINE OUT?UT ( HP) WATANA-TURBINE PERFORMANCE (AT RATED HEAD) • 4000 -(/) IL 3000 0 - I.&J (!) a: <l :I: g Q t= 2000 3 1000 24opoo FIGURE 8.71 .. .. I f it, L ~ j: t: r: .I h 1: l r j· !; l\ \ i t \ ll t fi ( \l r, q p f! H q ', ; ! il n I' l I l· ' ( I l. i' "' h. f, L r L I ' .. I 94 90 - 86 -... ~ C.• ->-0 z w 0 82 i'i: LL w 78 74 100 -•• ,_,,,_..__;;_,:.__...,...,.~.__,.__..;........,:;._,__""~ ........ ...;:.__.,' " .. , ""'%'"' ~-rttat eHtH:IflM'~~~wt ·m stfS'twes +«t itwtc -""r··, i! ·1 ,~ t 1·· -..._j r-1 UNIT ~2 UNITS I \ v I I I I I I -300 500 700 PLANT 0 UTPUT ( MW) WATANA ... UNIT EFFICIENCY (AT RATED HEAD) '- I ' I ' l t' -1100 FIGURE B. 72 l ... • ·' ·x.,-·-·· . ·~ ·tite<otrt&¥*1iit:JiiiWMHt't$1f'*i5UtMMnz&it' $ ili·rr•"·Eii ~"l't'ftWt'&f'~····+·;r· ···~ 620 -------~--------~---------~--------~----------~--~------~ 115 o GENERATOR RA ED POWER _........_.~ 600 ~------ RESERVOIR EL. t455 5aor----------4---------~~-------4--~------~--------~--------~ I I ii3EST EfFiC ENCY7 · 540~----~E~E~~L~1~-~l~4~05~~----k===~~Wfi~~~~~~~~~--------~ 520~--------~--------~--------~----------+---------~----~--~ ' ~--------~--------!40 100 120 160 UNlT OUTPUT-MW ISO 200 220 ., j t l i t· I l \ t t \: I' ,. l \' ! ! 1 \ \ i l ' DEVIL CANYON-UN\T OUTPUT FIGURE s.73 ~~~~) • .. . ~~ l: \ ... _/ . -• • t, 0 • -·· . . . ' : . . . ·-. . . . . . . ,, . . i ' . r 4._ "'-· """ L.,c. I L • --------------------------------------------------------------------~ ." 90 -I ~ 0 - ~------~~---------k--------~---------4----------~--~4000 b z UJ 0 80 iL. tL. liJ UJ z ~ ::;:) 1- 70 -m tL. ~--------4---------~--------~----~~-4----------~--~woo~ w ~ a: <i li U) i5 t: ~--------4-------~~--------~~-----------4------·----r-~--~2000~ 40,000 ------~---------r--~1000 80,000 120p00 160,000 200,000 TURBiNE OUTPUT ( HP) DEVIL CANYON -TURBINE PERFORMANCE (AT RATED HEAD} .. i," ' i ! 1 r~ 1' ! \ \ r \ \ \ '; \ I. L \' I" \4 ~~ fl ! FIGURE B.14 • L-----~------------------------------------------------------------------~ ~ I p i ) l t .. -fl. - l; z w ~ : .. ., .:U..lt: • • -~ • ~ 0 0 ·• :. ; . ' ·:J "1~·~~----., ·=-':"~~-·~····'~'', ·:-~-~., ........... ·~~·,.' . . .... . ' . . . . .. 94r-.---------~--------·~--------~--------~----------~----~ 0 82r-~--------~---------4----------r---------~--------~-------~ lL lL w 78~4---------~---------4----------~--------~--------~------~ 74~~---------+---------4----------+---------~---------+------~ 100 200 300 400 500 PLANT OUTPUT ( MW) DEVIL CANYON-UNIT EFFICIENCY (AT RATED HEAD) FIGURE: 6.75 •• .. ;. - • .. .... ··-·"·--··-----------------__________________________ _. .... ----------~-----------~ RAILBELT AREA OF ALASKA SHOWING ELECTRICAL LOAD CENTERS FlGURE 8.76 .. " t-Q ~ ·"'\'It r \ I I l L r j I l t l r ! r t· r r l !I I ., i. [ l t [ 2500 ---·---------------------- 2000 I t -:r: == 0 -(/) 1500 liJ ..J <( (/) >- 1--0 -a:: ..... td 1000 ..J t1J o~--~-------~-----------~----------~ 1965 . 1970 .. 1975 1980 YEAR HISTORICAL TOTAL RAILBELT UTIUTY SALES TO FINAL CUSTOMERS FIGURE B .. 77 -. !::". t • 1'1 ' . I l \' ! l I \ L \ r . l \ I \ \' I l; \ ' \ l· \ \ i n l asr-------------------------------------------------------~--~ I I I I 15 14 13 12 -tO ll 0 I I LEGEND HES"' GH : HIGH ECONOMIC GROWTH+ HIGH GOVERNMENT EXPENDITURE MES-GM :: MODERATE ECONOMIC GROWTH ·t MODERATE GOVERNMENT EXPENDITURE LES-GL :: LOW ECONOMIC GROWTH +LOW GOVERNMENT EXPE~DITURE LES • GL ADJUSTED : LOW ECONOMIC GROWTH +LOW GOVERNMENT EXPENDITURE T LOAD MANAGEMENT AND CONSERVATION I I I I I I I I IHES-GH I I I I I I z: ~ 10~------------------~------------------~~----------------~ (!) - ,, , , , , , / , , , , , , , , , .,, ~ __,.,. . .,.,.,-_,.,. LES -GL ADJ::JSTED 0~--~------~----~--~--------~--------~-----------_.--------~ 1980 1985 1990 1995 2000 2005 2010 YEAR lSER 1980 ENERGY FORECASTS USED FOR DEVELOPMENT SELECTION STUDIES FIGURE 8.78 .. • ['1• r l l t \ I a l ' \ \ l '~ r 1 t lf l I! l l ; ~ ,·1 ' j 'l ! !' J.:!, \!' 1; t • ECONOMIC SCENARIOS • PRIVATE ECONOMlC ACTiVITY • STATE FiSCAL POUCY ECONOMIC MODELS • i.S'CR SIATEWI DE MODEL • REGIONALIZATION MODEL o HOUSEHOLD FORMAl ION -~1 ECONOMIC, INDUSTRIAL, POPULATION AND HOUSEHOLD FORECASTS • ~-· INPUT DATA AND ASSUMPTIONS o END USE SURVEY • CONSERVATION PERFORMANCE AND COSTS • FUEL COSTS • COMWIERCIAL BUILDING STOCK ~ END USE MODEL (RED) l ELECTRIC ENERGY CONSUMPTION FORECASTS • ANNUAL ENERGY • PEAK DEMAND _,.__7 .. " _____________ ,......_.._ ..... "" ELECTRIC POWER FORECASTING PROCESS FIGURE 8.79 I t ' ~ .. D. I I I 14 / 3 2 / rHtGH / I /'". I LOW____....~· C--· ·- / / / 0 ~------~------~----~~--------~---------------- 1980 1985 1990 1995 YEAR 2000 DECEMBER 1981 BATTELLE LOAD AND 2005 2010 ENERGY FORECASTS USED FOR GENERATION PLANNING STUDIES~· FIGURE B.BO • .. • . . . • ' ... • • • • ' • ~ t . ~ p . .. • . Q' ~ ' • . t ,. • • " q • n ·. • n• .. It · • · .. • . . • • <# f> • • • fJ t' ., ....:: ... ' ~ f ~ t "' . ' b • ' . J: :!: .:zt -~ :E t: 0 0 > E' Q) c UJ r r- 300 1\;;: ~~\\ .;:: 260 200 • ~~; LEGErm ·----· .......... • • . Area Under ''l'hb Line !s Annu&l Cost of Best Thennal Option r (lneludlng Investment Com} -i I GATA_NA ONLy I N 19941 Energy Colt of B•at Thti'YOM Option Energy Cort of Sutltna Optio 1'1 Operating Costs of Thermal P1 In 1893 Emndad to 1994 antln U11 Shaded Ar.ta Aeprttttntl Plant Operatlnw In 1992 DIIPI0Citd tl't Wlltlna ::: 150 r--..: I ;~·~:~; :1.~·: ~~:~:~~Pfiii!L-·•••••••••••••••••••••••••••••••••••••·i-•••[ •• ~=~Undar This Limo I• Annual Colli of SUsltns Optiotl I ~ Area Under This Line is Annual : :::: :;:: :: 100 1-' ::::: ::;: :;:;:;:;:;:;::: :::::.:; ::::: :::: :;:::: :::: 50 :::: :::::::::::::;:::. :::::•:· :::: 1,000 :·:·: ·:·:· :::~:::::::::: .....---.r-: -· Operating Cost of Existing Capacity 1993/4 : (Avoided Coats of Fuel and O&M Only) • I : Ara~.Represents Annual Operating Costs : ,_ from Existing Generating Plsnt : Common to Both Susitna and ·:·:I ; Thtrmll Options :;~;~. :.:.:.:.:. ;:::::::: :::~ :;;~h~:;:~ ::;~: :m~ s::= =====: :=:::::::::::::::: ~ ·:·: :::::; :~::; Medium Growth Symm Energy d//b. .///-'"' :;~;~;~~ ~~m~~~ ' I I 3,000 4,000 Annuli E114tt'tiY Output GWh 6,000 ~ B. !II -ENERGY PRICING COMPARISONS-1994 • --~-·---·--------------------------------------------------------------------------------------------~ FIGURE \ l \ \ I I' I • ·~ ' Rev.1 380 360 340 320 300 -..c ~ 280 I -~ :E 260 -.. co .2 .. a.. 240" ., c t<l .:1 .. 220 0 (.) ~ Q) 200 c: w ·~ 180 ~'" 160 140 120 100 SYSTEM COSTS AVOIDED BY DEVELOPING SUSITNA COMPARED WITH BEST THERMAL OPTION IN MILLS PER UNIT OF SUSITNA OUTPUT IN CURRENT DOLLARS ~~ ~· I 'I I ~· • I COST SAVvNGS FROM SUSITNA INCREASING I OVER WHOLE LIFE OF PROJECT •• I ~· • I •.. ,. Increasing Thermal Fuel ## Costs Avofded -.._# >·--··· ... ·-*' ~~ ~"' #--# #-~~ # ~ II /.... Avoids Cost of a Further 200 MW Coal Fired Generat~ng Unit I • I •• J... Avoids Cort of 2 x 200 MW Coal Firod Generating Units ' ' Watana or. Stream in 1993 Devil C.:1ya!t on· Strtilin in 2002 -02 04 05 06 0;1 08 09 2010 11 12 13 5 6 7 8 9 2000 01 Yeen FIGURE S.82 -SYSTEM COSTS AVOIDED BY DEVELOPING SUSITNA ~-------------------,,~,-------------------------------------------------------------------------------94 I i ·,-I. • • "' t; 0 (.) En ... (I) = w 400 -I WATANA & DEVIL CA~YON IN 2003] 300 LEGEND '""\ ' ~' ·--~~~ Energy Cost of Best Thermal Option \ I Area Under This Line is Annual Cost of Best l'hermal Option ~1 \ (Including Investment Cost} , \ u n n n Energy Cost of Susltna Option ~~: ,..________ ----:~:, 1 1 Operating Costs of Thermal Plant in Use J I • :::::.• :.::::~.::.::: Plant Opmting ~ll\l;:j!'iilll~\ L..... r Area Under This Line is Annual Cort of Susitn~ a:.:· Dbplo~d by Susltn• ~·••••••••~••••••••••••••••••••~•••••••••~••••••••••••••••e••••••••••••~•••••••••••••••••••••••••••••••m••••••••a•••••etllll~ I ; : I : : I • I I • -~•••m••••••••-,••-••••••••••••n~---~ ! ~ : ~ 200 : ~ ! E 100 : ~ ! ~ : ~ l ~ l ~ l = I E : ~ ! E l ~ I r l Energy Output 5 Energy Output Watana ____....: Watana and Devil Canyon ~•1: I • I • : ~ : E ! ~ ! ~ Medium Growth System Energy Forecast for 1994; 6,044 GWh l ~ i ~~~ : ~M~ro 0 ~~~~~~~~~~~~~~~~~~-----~'----------------~'------~~----------~'----~------------._--. __ ~~~~~~A- 1,000 2,000 3,000 4,000 5,000 6,000 • Annual Energy output GWh ftPDrQ FIGURE aa3 -ENERGV PRICiNG COMPARISONS-2003 HUnto L-·----~-----------------------------------------------------------· ~--------n---------------------------------------------------------------~--~