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Thayer Creek Project, A Reconnaissance Report, October 1979
~ THAYER CREEK PROJECT A Reconnaissance Report ALASKA POWER AUTHORITY LIBRARY COPY PLEASE DO NOT REMOVE FROM OFFICE: STATE OF ALASKA ALASKA POW/ER AUTHORITY Anchorage, Alaska By HARZA Engineering Company Chicago, Illinois October 1979 THAYER CREEK PROJECT A Reconnaissance Report Prepared for the State of Alaska Alaska Power Authority Anchorage, Alaska by Harza Engineering Company Chicago, Illinois October 1979 | HARZA ENGINEERING COMPANY CONSULTING ENGINEERS October 15, 1979 Alaska Power Authority Suite 31 333 West 4th Avenue, Anchorage, Alaska 99501 Attention: Mr. Eric P. Yould Executive Director Subject: Thayer Creek Project Summary Letter Gentlemen: We present the results of our reconnaissance study of the Thayer Creek Project. The study includes technical, economic and environmental evaluations of the Project. We recommend that a feasibility study leading to an FERC license application be made of the Project, if financing at an interest rate equal to or less than 2 percent can be obtained and if a reconnaissance study of coal or wood-fired electricity generation and the availablility of coal or wood fuel resources does not show that type of project to be more attractive than the Thayer Creek Project. The following paragraphs briefly describe the Project and the studies which were made. The Thayer Creek Project The Thayer Creek Project is located at a falls on the creek of the same name, about 6 miles north of the town of Angoon on Admiralty Island in Southeast Alaska. The Project would have an initial installed capacity of 400 kW and at full production level (4 units) would produce about 2,560 MWh in an average year. 150 SOUTH WACKER ORIVE CHICAGO. ILLINOIS 6GO606 i TEL. (312) 855-7000 CABLE: HARZENG CHICAGO TELEX 25-3540 Alaska Power Authority October 15, 1979 Page Two The Table of Significant Data at the end of this letter con- tains pertinent data on the Project. A plan and sections of the Project are shown on Exhibits T-2 and T-3 of the report. The Project will consist of a dam, spillway, intake, penstock, powerstation and transmission line. The dam will be a concrete gravity structure containing an uncontrolled spillway. Maximum dam height will be about 56 feet. Water will pass through a 4.0 foot diameter steel penstock 160 feet long. A powerstation will be constructed near the base of the falls. The powerhouse will be a prefabricated metal building containing two vertical- shaft fixed-blade propeller turbines. Each turbine will be directly coupled to a generator rated at 200 kW. Power from the Project will be transmitted to Angoon over a 6-mile long, 12.5-kV transmission line. A 0.4-mile long submarine cable crossing will also be required. A preliminary identification of the potential environmental impacts of the Project shows that there do not appear to be any critical environmental issues which would preclude project development, except for the proposed wilderness designation of Admiralty Island. The problem of wilderness land designation could be avoided if the land were selected by the local native corporation before the designation is made. Anadromous fish spawn below the falls, but construction and operating proced- ures can be adopted that will reduce any adverse impact. Costs The construction cost of the Project includes the direct cost of civil works, contractor's overhead and profit, purchase and installation of equipment, contingencies, engineering and owner's administration, but excludes price escalation beyond the date of the estimate and interest during construction. The estimated construction cost of the Project, at September, 1979 price level is $9.4 million. Operation and maintenance cost for the Project is estimated at $40,000 per year at September, 1979 price level. Alaska Power Authority October 15, 1979 Page Three Economics A comparison of benefits produced by the Project, as measured by the cost of alternative diesel generation, with the cost of the Project shows that the Project has a benefit-cost ratio of 1.19 at an interest rate of 2 percent assuming differential fuel cost escalation of 2 percent. The average cost of energy over the 50-year life of the Project, at September, 1979, price level, would be 22.3 cents/kWh. This compares with 28.4 cents/kWh for the diesel alternative. Schedule The Project could enter service by the beginning of 1985, if an organizational framework is developed, financial feasibility is established, and feasibility studies are started in the fourth quarter of 1979. Conclusion We find the Thayer Creek Project to be attractive if financing can be obtained at an interest rate of 2 percent or less. We recommend that financing alternatives be investigated as soon as possible. Concurrently, a reconnaissance level study should be made of the use of wood and coal as a fuel to supply power to Angoon. The study should include an evaluation of both direct combustion and biomass conversion. A decision can then be made whether to implement the Thayer Creek Project, based on the availability of suitable financing and viable alternative projects. We would be pleased to provide you any assistance you may require in these matters. Very truly yours, we £? LLLEL.. Arthur E. Allen Project Director TABLE OF SIGNIFICANT Thayer Creek RESERVOIR Water Surface Elevation, ft msl Normal Maximum Minimum Tailwater Elevation, ft msl Type of Regulation HYDROLOGY Drainage Area, sq mi Avg. Annual Runoff, cfs/mi2 Streamflow, cfs Maximum Monthly Average Annual Minimum Monthly DAM Type Height, ft Top Elevation, ft msl Dam Volume, cy SPILLWAY Type Crest Elevation, ft msl Width, ft Design Discharge, cfs PENSTOCK Type Diameter, ft Length, ft Shell Thickness, in DATA 71 71 24 None 64.3 6.3 75) 405 150 Conc. Gravity 56 88 6,420 Conc. Ogee aL 40 11,000 (22,000)2/ Steel 4.0 160 On875 1/ Discharge capacity with flow overtopping dam TABLE OF SIGNIFICANT DATA (Cont'd) Thayer Creek POWERSTATION Number of Units (Initial) 2 Turbine Type Propeller Rated Net Head, ft 45 Generator Unit Rating, kW 200 Full Load Discharge, one unit, cfs 64 POWER AND ENERGY Installed Capacity, kW 400 Firm Capacity, kW 210, / Avg. Annual Energy Generation, MWh 1576= Avg. Plant Factor, % 45 COSTS AND ECONOMICS Construction Cost, $x106 9.4 Unit Cost, $/kW inst 23,500 B/C Ratio @2% with 2% fuel escalation 1.19 Average Cost of Energy, cents/kWh 22.3) 1/ Average annual river flows could produce 1752 MWh 100% of the time, however this generation will not be utilized initially because of system energy demand. THAYER CREEK DETAILED TABLE OF CONTENTS - T Page Chapter Summary Letter Table of Significant Data Table of Contents i Foreword T-F-1 Purpose and Scope T-F-1 Background and Previous Studies T-F-1 Authorization T-F-2 Acknowledgements T-F-2 ‘is Project Setting T-I-1 Location and Access T-I-1 Population and Economy T-I-1 Electric Power System T-I-1 Utilities Existing Facilities Power Market Forecast ead Hee wee Topography T-I-3 Geology T-I-3 Hydrology T-I-3 Ecology T-I-4 II. The Thayer Creek Project T-II-1 General Description T-II-1 Introduction T-II-1 Project Arrangement T-II-1 Project Functional Design T<-II=2 Hydroelectric Power Production TT, Geology, Foundations and Construction T-II-2 Materials Description of Project Facilities T-II-4 Dam and Spillway T-II-4 Power Intakes T-II-5 Penstock T-II-6 Powerstation T-II-6 ABIES IV. DETAILED TABLE OF CONTENTS (Cont'd) Switchyard and Transmission Access Roads Reservoir Spoil Disposal Environmental Aspects Project Constuction First Year Second Year Third Year Project Costs Construction Cost Operation and Maintenance Cost Project Selection and Operation Stream Regulation Characteristics Type, Number and Capacity of Generating Units Power and Energy Production Economic Analysis Methodology Alternative Sources of Power Wind and Solar Load Management and Energy Conservation Interconnection Other Hydro Wood and Coal Diesel Economic Criteria Economic Comparison Cost of Energy Recommendations and Implementation Recommendations Organizational Framework and Financing Preconstruction Activities Implementation Schedule -ii- HHA . HAH NOU WHE vaAwPY EXHIBITS General Location Map General Plan Project Sections Detailed Cost Estimate Project Selection Cost of Energy Implementation Schedule APPENDICES Geology Hydrology Environment References -iii- FOREWORD (T) Purpose and Scope of Report This report is to document the results of a reconnaissance level study of the Thayer Creek Project near Angoon on Admiralty Island in Southeast Alaska. The objective of the study is to determine if an application for license to the Federal Energy Regulatory Commission (FERC) should be made. Also, an evaluation of alternative energy sources for Angoon is presented. The scope of the study includes the following work items: Lis Size installation and estimate project power and energy production in relation to system loads. 2. Prepare reconnaissance level analyses, preliminary design, geologic maps and layouts of appurtenant structures. Sie Perform an environmental reconnaissance and identify the potential environmental impacts of the project. 4, Make a preliminary assessment of the safety hazard, if any, caused or introduced by the project. Bye Estimate the construction, operation and mainten- ance costs and service life of the project. 6. Evaluate energy alternatives and prepare an economic analysis of project. 7. Prepare a final report documenting the studies. Background and Previous Studies Studies of hydroelectric power development in the Angoon area have considered the development of Thayer Creek since stygies completed by the Federal Power Commission in 1947 [1]—% An inventory study [2] prepared for the Alaska Power Authority (APA) in 1977 also selected Thayer Creek as the site for power development. The present study is a direct result of the 1977 study. 17 Reference listed in Appendix D. Eyl Authorization The work was carried out under a contract between the APA and Harza Engineering Company, effective as of June l, 1979. Funds for the study were provided by the State of Alaska. Acknowledgements Harza acknowledges and appreciates the valuable assistance and advice offered by the staffs of the following agencies: Alaska Power Authority Alaska Power Administration Tlingit & Haida Regional Electrical Authority U.S. Forest Service, Tongass National Forest U.S. Geological Survey Alaska Department of Fish and Game Admiralty Island Citizens' Council T-F-2 Chapter T-I PROJECT SETTING Location and Access The Thayer Creek Project is located at latitude 57° 35'N and longitude 134° 37'W, near the town of Angoon on Admiralty Island in Southeast Alaska. See Exhibit T-l. The Project develops the head between the top and the bottom of a falls on Thayer Creek at a point about 0.2 miles upstream from Chatham Strait. Access to the damsite and the powerstation site is gained by boat to the mouth of Thayer Creek and from there by foot. Population and Economy The Project would serve the town of Angoon. The majority of the inhabitants of the project area are Alaskan Natives, predominantly Tlingit Indians. The population of the area is about 500 and accounts for almost all the population of Admiralty Island. The major commercial activity of the project area is fishing. Electric Power System Utilities Angoon is served by the Tlingit and Haida Regional Elec- trical Authority (THREA), a rural electric cooperative with offices in Juneau, Alaska, which serves 5 towns in Southeast Alaska. Existing Facilities All power in the project area is generated by small diesel- electric units located in Angoon. ‘The power is distributed directly from the powerstation; there are no transmission lines interconnecting the town with other areas. Table T-I-l lists the generating units serving the area. All units are owned by THREA. Table T-I-l ANGOON ELECTRIC SYSTEM EXISTING DIESEL GENERATING FACILITIES Nameplate Capacity, kW l/ Unit No. Unit Total Firm= 1 300 2 165 3 400 865 465 ay Largest unit out of service. Power Market Forecast The forecast of future electric power needs is based ona current forecast prepared for the utility (THREA). A fore- cast of the power and energy generation requirements in the project area is shown on Table T-I-2. Future requirements for THREA in Angoon have been estimated by a Rural Electrification Administration (REA) team [3] in cooperation with THREA. The current forecast, made in May 1979, is substantially lower than previous forecasts, basically because the previous forecasts were overly optimistic and recent rate increases have curtailed increases in per capita consumption. Over the ten-year forecast period the REA pre- dicted per capita consumption to remain constant with load growth coming from new connections. The combined load served by THREA is forecast to increase at 1.5 percent per year. Table) T-1—2 POWER AND ENERGY GENERATION REQUIREMENTS Peak Energy Year Demand, kW Generation, MWh/yr 1978 (actual) ye 680 1983 304 1200 1988 327 1290 1993 353 1390 TZ There are tentative plans to build a cold storage plant in Angoon, but this load has not been included because of the uncertainty of its magnitude, timing and connection to the THREA system. Topography Admiralty Island has rolling, rugged mountainous terrain rising to 4600 feet at Eagle Peak, near Juneau. Thayer Creek drops from about El. 400 at Thayer Lake, passes through a canyon, and then enters Chatham Strait. At the base of the canyon there are a series of cascades with a base near tidewater at El 24. The Project would develop the last of these cascades which is about 10 feet high. Geology The canyon, which has been eroded by Thayer Creek, was apparently caused by the rapid rebound of this part of Admiralty Island following the melting of late Pleistocene glaciers and by possible uplift along the Chatham Strait Fault. Rock in the area of project structures is part of the Devonian-Gambier Bay Formation and consists of hard foliated marble. Earth- quakes are common in the project area and the Project could be subject to severe shaking. More information on project geology is presented in Appendix T-A. Hydrology The climate of the project area is largely maritime with occasional incursions of continental air masses. The climate is mild and humid with much precipitation. Average annual temperature is 41°F with lows ranging from -10°F in the winter to highs of about 85°F in the summer. Precipitation varies greatly with elevation and location. At Angoon mean annual precipitation is about 47 inches. Thayer Creek at the damsite has a drainage area of 64 square miles and an average annual inflow of 405 cfs or 6.3 cfs/mi2. December through April are low flow months with average flows below 300 cfs. High flow months are May, June and October, with average flows greater than 600 cfs. More detailed information on project hydrology is present- ed in Appendix T-B. Hydrologic information relating to pro- ject operation is presented in Chapter T-III. Dot —S Ecology Vegetation in the project area is typical of hemlock- spruce coastal forest. The area has not been logged. Wildlife in the project area includes brown bear and Sitka black-tailed deer as well as many of the 200 bird species common to South- east Alaska. Thayer Creek is a catalogued anadromous fish stream and reportedly supports spawning runs of pink, chum and perhaps coho salmon. More information on the ecology of the project area is presented in Appendix T-C. Project environmental impacts are discussed in Chapter T-II. T-I-4 Chapter T-II THE THAYER CREEK PROJECT General Descripition Introduction Thayer Creek falls is a long series of cascades that do not provide any significant drop at any one point where a substantial net head could be developed. However, with a moderately high dam an initial generating capacity of 400 kw can be installed with a water demand that does not exceed the flow in the river except for a small period of less than 5 percent of an average year. In effect, the required installed capacity will be dependable capacity, with the plant operated on a run of the river basis, with no expected drawdown of the pool below the spillway crest level. The spillway can be expected to operate some 95 percent of the time. This chapter gives a description of the Project, the functional and preliminary design of the major project elements, the schedule for the construction of the project and the estimated project costs. Project Arrangement The Thayer Creek Project will consist of the following principal elements: a. A concrete gravity dam across the river, founded on rock, with an uncontrolled ogee spillway with crest at El. 71 in the river section. b. Individual intakes for the initial and future instal- lations, containing slots for conduits, which are located on a bench on the north abutment, and a tem- porary diversion conduit with closure gates, located through the dam at one side of the spillway. Ce A power conduit approximately 160 feet long to be constructed as an exposed steel penstock to convey water down to a powerhouse located just downstream of the base of the last waterfall on the creek. d. A powerhouse containing the turbines, generators and electrical switchgear and an adjacent switchyard to contain the transformer and transmission pull-off structures. Tate e. Other facilities, including access road and transmission line. Exhibit T-2 shows a plan of the project general arrangement. Exhibit T-3 shows sections through the major structures includ- ing the dam and spillway, the penstock and its anchor blocks, and the powerstation. A summary of significant data relating to the project is shown on the table at the end of the Summary Letter. Project Functional Design Due to the availability of water at the damsite, the Pro- ject will be designed to provide both energy and dependable capacity for the town of Angoon and its environs. The plant will operate essentially as a run-of-the-river plant with little drawdown of the pool below spillway crest level. The initial two units to be installed can meet the entire system energy requirements during the first 18 years of the project's life. Hydroelectric Power Production The powerplant initially will have two generators rated at 200 kW each, powered by fixed-blade propellor turbines of 281 Hp each. The total initial installed generating capacity will be 400 kW. At full utilization (4 units) the Project will produce 2560 MWh in an average year. Net operating head will be in the order of 45 feet with the reservoir at the spillway crest level and two units opera- ting. Geology, Foundation and Construction Materials A detailed description of the site geology is presented in Appendix T-A. Thayer Lake and much of Thayer Creek is a juvenile drainage basin reflecting a recent glacial history with numerous small lakes, muskegs and a poorly integrated drainage system. However, near the coast, where the proposed dam would be located, Thayer Creek has eroded a deep, steep-sided canyon. The depth of the canyon, which is from 300 to 400 feet, apparently is caused by uplift of this part of Admiralty Island resulting from the rapid rebound of Admiralty Island following melting of Late Pleistocene glaciers and by possible uplift along the Chatham Strait Fault. Rapids are located T-LiI-2 along the creek near the coast and the valley is narrow and sides are steep, in places precipitous. Valley sites are covered with thin overburden deposits of talus and trees, which often show signs of hill creep (bent tree trunks, small shallow slumps). These are indicators of oversteepened slopes which are confirmed by the 45° slope of the canyon walls. The many indicators of the instability of overburden on the valley sides suggest that a reservoir near the mouth of Thayer Creek would be rapidly filled with debris and/or that installations in the area could be damaged by debris avalan- ches if not properly protected. Rock found at the site belongs to marbles of the Devon- ian-Gambier Bay Formation. At the dam site and in the power- plant area, the marble of the Gambier Bay Formation is a medium grey, finely crystalline, hard foliated marble. Folia layers are often laminae but vary to 6 in. apart. Layers are generally coated with chlorite mica. Foliation generally strikes NW, parallel to the coast and dips 40°NE. The rock mass is intersected by a strong set of vertical joints that are essentially at right angles to folia- tion. Another set of vertical joints strikes N-S. Both joint sets appear to locally control the direction of streamflow. Proximity of the site to Chatham Strait and the Chatham Strait Fault would suggest that movement on this fault could severely shake the site. While the fault is generally consid- ered to be inactive, its length and apparent relationship to the Fairweather Fault would make it suspect. Therefore, structures should be designed to withstand strong shaking. The powerplant site, which is near the coast, could also be susceptible to tsunamis originating on the Chatham Strait Fault. Stripping of the dam's abutments will require removal of organic matter and soil from both the foundation area and from the slopes to an elevation of possibly 200 feet. The strip- ping above the dam's foundation area and penstock alignment would consist of removing all unstable material. Some trim- ming and shaping of rock cliffs may also be required. A modest grout curtain to minimize uplift pressure should also be adequate. It is recommended that the channel area curtain consist of holes 10 feet deep drilled on 5 feet cen- ters and angled N85E. Abutment grouting of holes 10 feet deep on 10 feet centers and drilled normal of the slope is also recommended. Dior —3 The powerplant should be founded on bedrock. Protection from tree blow-down and debris avalanche should be provided by cutting larger trees in the area and removing soil and talus as necessary. Aggregates will be needed for about 6600 cubic yards of concrete in the dam, penstock supports, and powerhouse sub- structure. The aggregates must be obtained from a source other than an area near the project site and be transported by barge to the project site. Aqgregate sources in the Project area contain schist and therefore are not suitable for concrete aggregate materials. The contractor, will therefore, elect to obtain the aggregates from the closest source with docking and loading facilities that provide transport of construction materials. Known sources are in the Ketchikan and Seattle areas. The contractor could also develop a quarry on the same island (Admiralty) where the intrusive volcanic rock outcrops near the shoreline, provided that the suitable rock is not in an area to be designated as wilderness. However, this would involve towing and constructing a barge-loading facility that would permit loading through most of the high and low tide range. This probably would be more expensive than obtaining the aggregate from an existing developed source. Description of the Project Faciliites Dam and Spillway The dam will be a concrete gravity dam with an uncontrolled ogee spillway crest over the deeper, river section. The crest of the spillway is set at elevation 71.0 and the top of the dam at elevation 88.0. The dam, with a backslope of 0.7h:lv, will have a maximum height of 56 feet in the river section. Half of the dam height is attributed to providing dead storage for the large amount of pebble and stones moved along the bed of the river by the very large and turbulent flood flows expected every year. The 25 foot depth was arbitrarily chosen on the basis of evidence at the site of a large delta formation of stones and pebbles at the mouth of the river and the amount of talus debris on the canyon slopes. If the project offers economic possibilities of being a viable project, studies could be carried out to determine a more accurate volume for this consideration and to devise some possible means of flushing this material through the dam when excess water is available. The results of such studies could reduce the construction cost of the dam and maintenance costs T-11I-4 related to keeping stones away from the power intakes at the face of the dam. The probable maximum flood for Thayer Creek has been determined to be in the order of 43,000 cfs. Conservative assumptions for the outflow characteristics of the lake demon- strate that a flood of this magnitude with a volume of approx- imately 74,000 acre-feet would be attenuated by at least one half - to about 22,000 cfs, by storage routing through Thayer Lake. Considering also that the project lies in an area not to be developed or to be inhabited in the future it was decided to dimension the spillway for 11,000 cfs, or 50% of the prob- able maximum flood flow expected to arrive at the dam site, and to allow the PMF to pass over the non-overflow portion of the dam (together with surcharging the spillway). This results in a spillway equal to the width of the exist- ing river channel and, except for extremely rare occurances, confines discharges to the existing channel. The spillway will be provided with a flip bucket to force flow away from the base of the dam. No storage effect is considered available in the project's reservoir to attenuate the peak flood inflow. In passing the probable maximum flood discharge, the top of the dam will be surcharged by 5 feet of water. The dam would be stable under this head, and no significant damage would be expected to be abutments. A short concrete, apron would be provided downstream of the dam to channel the water towards the river and to carry the water over the penstocks, should overtopping of the non-overflow sections occur. A grout curtain will be provided along the entire length of the concrete dam near the upstream face of the dam. The entire foundation of the dam and spillway will be stripped to sound rock. The dam and spillway will require about 6,420 cubic yards of concrete. Power Intakes The power intakes will be located on a bench at the right side of the existing river channel, between the spillway train- ing wall and the north river abutment. One intake will feed the initial two units and the other will be provided for a future installation of an additional two units. The power intakes will have bell-mouthed entrances and be provided with Telia guides and seal plates on the upstream face of the dam for interchanging trashracks with bulkhead gates which can be lowered from a hoist at the top of the dam. The intake water passages will have slots for emergency closure gates operated from hoists at the top of the dam. Penstock An initial exposed 4.0 foot diameter penstock with a total length of about 160 feet will connect the initial intake to the powerstation. The exposed penstock will be provided with intermediate concrete supports in the horizontal reach and anchor blocks where it changes direction in dropping to the powerstation. The penstock is located to allow for the possible future installation of an additional penstock to feed two additional units to bring the total installation to four generating units. Between the powerstation and the lower anchor block, a penstock bifurcation will be provided to feed the individual unit turbines. The penstock bifurcation will be supported on a rock backfill between the down slope anchor block and the powerstation and will be encased in concrete. The escarpment face behind the penstock will be cleared of possible rock spalls and be stabilized with rock bolts and wire mesh. Powerstation The powerhouse will have a reinforced concrete substructure with a prefabricated metal type superstructure above the gener- ator room floor. Unit width would be approximately 9 feet. The turbines would be mounted in formed pits 6 feet square above the draft tubes. The overall dimension of the initial powerplant super- structure containing two units and an erection area will bea building 32 feet long by 12 feet wide by 20 feet height. The two turbines will be vertically set fixed blade pro- pellor type available as standard inventory "package" models, each rated to produce at least 281 horsepower at a net head of 45 feet at 1200 rpm. At the rated output and head, each turbine will discharge 64 cfs. T-II-6 The generators and turbines will be connected by a vertical drive shaft setting. The generator will be rated at 250 kVA at 60° C temperature rise, 0.8 powerfactor and 60 hertz. Each generator will have a continuous overload rating of 15 percent. Switchyard and Transmission Circuit breakers will be of the air magnetic, or vacuum interruptor type as appropriate. They will be rated to inter- rupt the maximum expected fault current and will be used to put the unit on-line during the normal start-up sequence and to take the unit off line. Station service power will be supplied at 480-V, through 3-phase, dry-type transformers and 480-V circuit breakers. All protective relays and all control devices for complete manual and automatic operation of the generating units will be provided. Supervisory control equipment will be provided to permit remote control, indication, and communication of powerhouse generating control from a remote central control room located at Angoon. The generators will be connected to a power transformer located in a small yard on the upstream side of the powerstation. The transformer will be rated at 575 kVA. The transformer will be connected to the Angoon substation by a single 12.5-kV circuit about 6.4 miles long, including a 0.4 mile long submarine cable crossing at the mouth of Kootznahoo Inlet. The powerstation will be provided with a light bridge crane, supported on separate columns and support beams for purposes of unloading and erection during construction and servicing. Accessory electrical equipment for the control and protec-— tion of the powerplant and miscellaneous mechanical equipment will be provided in the powerhouse. Access Roads There are no access roads north of Kootznahoo Bay at the present time and none are foreseen for the future. There are escarpments along the edge of the water between Kootznahoo Bay and the project site that preclude the possibility of construct- ing economical overland access to the site. Also, since no docking facilities are available on the north side of Kootzna- ale 7) hoo Bay it would be more practical to consider constructing a timber crib barge loading and unloading facility for construc- tion and maintenance of the project near the outlet from Thayer Creek. The timber crib facility would not be extended out into ex- pected low tide pools. Unloading would be done during the high tide sea levels. Movement of barges would be limited to fair weather periods, because storms on Chatham Straits can create very rough water in a short time, thereby making docking maneuvers impossible. An access road could easily be constructed from the timber crib to the powerhouse on the north side of the river and be extended on a bench cut up to the dam site. Reservoir The reservoir created by the uncontrolled spillway crest level of El. 71.0 will be about 0.8 miles long and be entirely confined to the canyon in the region of the existing falls. The reservoir will be surcharged above El. 71.0 most of the time. When inflows exceed turbine discharges, the excess flow is discharging over the spillway crest. Clearing of the reservoir should be carried out in the areas between the stream bed and El. 75 at either side of the streambed. Spoil Disposal Overburden, containing organic matter and decomposed rock removed from required excavations at the damsite, will be temporarily stockpiled and then placed into waste disposal areas which were cleared and used as staging areas during con- struction. The material will be placed in compacted layers, finished off with stable slopes, and seeded. Environmental Aspects An environmental reconnaissance was carried out and the potential impacts of the Project on the environment were identified. Details of this investigation are presented in Appendix T-C. The damming of Thayer Creek above the end of the falls will not affect the passage of anadromous fish since the final Tel 3 10 foot fall (farthest downstream) serves as a natural bar- rier. The construction of the Project may have some adverse effect on the migratory and resident salmonid population below the falls, but proper construction procedures and scheduling could minimize these impacts. At the present level of study there do not appear to be any major adverse environmental impacts of the Project which would prohibit its construction or greatly restrict its operation, provided project lands can be acquired by Kootznoo- woo, Inc. (Angoon's native corporation) or other appropriate private party. The project site is located on lands in the Tongass National Forest which are being recommended for inclusion in the Wilderness System. Water projects are not permitted on wilderness lands except by authorization of the President. Project Construction The project construction will be carried out by separate supply and civil works construction contracts. A single general contractor will be engaged to build the project. The contractor will be required to provide access to the site by constructing a timber crib barge loading facility capable of functioning at high tide. The contractor must also: 1) construct an access road to the powerstation and to the dam site above; 2) clear and strip the power house and dam sites; and 3) provide for his power requirements during construction. Actual construction can be completed in a period of two and a half years including three summer seasons. The contractor will use the first spring season to construct a timber crib loading facility for access to the site, mobilize his equip- ment and work force, occupy the site, and establish his shops and working areas. First Year When the contractor has constructed the loading facility, completed move-in, and finished assembling his shops and main- tenance facilities he will begin transportation of materials, including concrete aggregate, to the site. He can then begin clearing and stripping brush, overburden, and loose and weathered rock from the dam and powerhouse foundation areas. By the time the foundation areas are prepared for placing concrete, the contractor should have his batching plant erected and be ready for concreting operations. Diversion would slg) commence in August of the first year by building a Cellular Sheet Pile Cofferdam to permit dewatering of the south half of the dam foundation by confining flows against the north (right) abutment. Initial concrete placement in the dam will be for the left half of the dam to at least El. 55.0. This part of the dam will contain a 7.0' wide by 7.5' high formed diversion conduit with a bell-mouthed entrance set upstream of the dam to permit incorporation of a diversion closure gate operated from the top of the dam along the upstream face of the dam. When the dam is completed, the diversion closure gate would be closed in August of the third summer season. August is normally the lowest flow month in the summer. While initial river diversion is being effected, the con- tractor will simultaneously begin work on the powerhouse below the falls. The total concrete to be poured in the dam is approximate- ly 6400 cy. The largest pour the contractor will have to make ina 10 hour shift is in the order of 170 cy. A concrete batching and mixing plant with two 1.5 cy. mixers would provide ample time for charging, mixing and unloading cycles to provide concrete as necessary. The batching plant would be located on a bench close to the downstream end of the dam. Concrete can be placed in lifts by using one or more truck mounted mobile cranes. Penstock assembly must begin before the end of the first year so that sections to be embedded in the dam will be avail- able when needed. During the first year, work will begin on clearing the transmission line. It is expected that work will be significantly curtailed through the winter months of December, January, February and March due to snow, low temperatures and limited hours of daylight. If winter conditions are not too severe, or should the contractor need to make up lost time, it would be possible to continue on the powerstation and transmission line erection during the winter season. Work would be expected to be less productive and should not be necessary under normal conditions. T-II-10 Second Year By mid summer of the second year the contractor will com- plete erection of the prefabricated metal superstructure for the powerstation and installation of auxiliary electrical and mechanical equipment. He will then commence installation of the turbine, genera- tors and power transformer under the supervision of manufact-— urer's representatives. The transmission line pole erection will be completed and work initiated on stringing the conductors. In July of the second year the river will be diverted through the concrete formed diversion conduit in the dam and work will be initiated on the north half of the gravity dam. Concrete placement will be done simultaneously over the entire dam axis. Third Year Early in the third summer season the Contractor will com- plete the installation of the electro-mechanical equipment and complete the transmission line into Angoon on the south side of Kootznahoo Bay. The contractor will complete concrete placement in the dam by the end of June and then close the diversion conduit to fill the reservoir. In July of the third year the contractor can begin test- ing the units and making the necessary adjustments and correc— tions to bring the units on line before the end of September. Cleanup and restoration of all construction areas at the dam site and around the powerstation will proceed simultaneously with testing of the units. The contractor will remove his equipment and material from the site during August and September. The construction schedule is indicated on Exhibit T-7. Project Costs The construction and operation and maintenance costs of the Project are estimated as discussed below. The costs are estimated at a September 1979 price level. Tel al Construction Cost The construction cost of the Project is summarized on Table T-II-1 and a detailed estimated is shown on Exhibit T-4. The construction cost includes the direct cost of civil works contractor's overhead and profit, purchase and instal- lation of equipment, contingencies, engineering, and owner's administration, but excludes price escalation beyond September, 1979, and interest during construction. Table T-II-1 CONSTRUCTION COST OF PROJECT (In Thousand Dollars at September 1979 Price Level) Item Cost Mobilization 1050 Land and Land Rights 102 Reservoir Clearing 38 Diversion and Care of Water 317 Dam, Spillway and Intake 2467 Waterconductor 312 Powerhouse 122 Mechanical and Electric Equip. 382 Roads 740 Transmission 860 Subtotal Direct Cost 6390 Contingencies (25% +) 1598 Total Direct Costs 7988 Engineering and Administration (18% +) 1412 Total Construction Cost 9400 Detailed estimates of quantities are calculated from the project plans, and unit prices or lump sum costs are estimated for each item of work. The items within each project feature are estimated either as part of a general construction contract or an equipment pur- chase contract. The unit costs of labor and locally available construction materials were obtained from local sources. Con- struction equipment unit costs are developed from lower U.S. T-II-12 hourly rates adjusted to local conditions. Unit prices were verified by checking recent bids on the Green Lake Project located near Sitka and by experience of the Corps of Engineers in Alaska. Unit costs for the principal items of work are based on a construction plan designed to implement the Project in accordance with the schedule as shown on Exhibit T-7. The direct cost estimated for the permanent equipment includes purchase, delivery, and installation. The major equipment items include: the turbine and governor; generator and exciter; transformer and terminal equipment switchgear; and powerstation crane. The prices of major equipment items are estimated based on recent experience with similar equipment, and, when possible, on preliminary quotations from manufacturers. To allow for unforeseen construction problems, changes in design, and errors or omissions in estimating, a contingency allowance of 25% is added on all costs. Based on data obtained from other hydroelectric projects, an allowance of about 18% for engineering and owner's overhead expenses is added to the total of the preceding costs. This consists of 15% for engineering and monitoring of construc- tion and 3% for owner's overhead costs to be charged against project construction. Operation and Maintenance Cost The Project will be equipped for remote control operation from Angoon. Routine operation and maintenance expenses are estimated at $40,000 per year. T-ti— 13 Chapter T-III PROJECT SELECTION AND OPERATION This chapter describes the selection of the stream regula- tion characteristics for the Thayer Creek Project and the type, number, and capacity of generating units. The operation of the Project in relation to power system loads is also discuss- ed in this chapter. The selection of the Thayer Creek Project from among other possible sources of generation is discussed in Chapter T-IV. Stream Regulation Characteristics Thayer Creek has power production potential far in excess of forecast system requirement through the last year of poten- tial project life. By 2033, the last year of the 50 year life for the Thayer Creek Project, assuming initial operation by the end of 1984, Angoon will have a peak load of 640 kW and require 2,520 MWh of energy. The average annual flow in Thayer Creek would be capable of producing 1300 kW of contin- uous power or 11,500 MWh of energy per year (at the head of 45 feet). Therefore, it was decided that the Thayer Creek Project should be a run-of-river hydro plant. A flow duration curve for Thayer Creek is shown on Exhibit 7-5. At the initial project installed capacity of 400 kW, the plant would require a flow of about 120 cfs, which is avail- able at least 85 percent of the time. A flow of about 65 cfs, which will operate one 200 kW unit, is available almost 100 percent of the time. With minimal pondage for hourly regula- tion to meet peaks, the Project should be able to supply power system needs through most of its life. Type, Number and Capacity of Generating Units A 400-kW initial installation at Thayer Creek will supply the needs of the Angoon system to the year 2002. A two unit installation is selected to improve reliability and effi- ciency. The Project will be capable of expansion by the addition of two more 200-kW units. Each of the units should be of a "package-type" includ- ing a fixed blade propeller turbine. This type of unit was selected because of the suitable head on the Project and the low cost of this type of unit. slot Power and Energy Production The Project will provide replacement energy in the system. The Project will also be able to produce about 330 kW of power, 90 percent of the time. Some drawdown might increase this amount. Whenever the water supply permits (about 85 percent of the time), the project could produce 400 kw. The Project is assumed to be capable of meeting the system's energy requirment to the year 2033 at which time the system will require 2560 MWh/yr. Peo Tal To Chapter T-IV ECONOMIC ANALYSIS Methodology An evaluation, at the reconnaissance level, indicates the economic attractiveness of the Project. The costs of produc- ing the same power and energy produced by this Project as by an alternative source of generation is taken as the benefit accruable to the Project. The benefits and costs of the Pro- ject are compared under various economic assumptions to deter- mine benefit-cost (B/C) ratios. As an additional indication of economic attractiveness, the annual cost of energy as produced by the Project was com- pared with the annual cost of generation from alternative sources over the Project's life. Alternative Sources of Power The various types of projects available to serve the pro- ject area were screened to determine the most likely alternative source of generation. Costs were estimated for that alternative. The following types of alternatives have been suggested: diesel; other hydro; wood waste; wind; solar; interconnection with other systems; and energy conservation. Of these alter- natives, the first three offer the most promise for the pro- ject area and are discussed in more detail at the end of this section. The others are not as attractive for the reasons presented in the following paragraphs. Wind and Solar Wind is a form of solar energy. Both the use of wind to drive a generator directly and the use of solar energy for heating or for conversion to electricity are not practical alternatives for Southeast Alaska in the near and intermediate term. A wind demonstration project, sponsored by the State of Alaska, is currently underway in the Aleutians. The project is small, will require an energy storage system to provide continuous energy, and present economics do not justify the installation of such units on even a small scale commercial basis. Direct use of solar energy has found increasing appli- cation in areas of the U.S. having abundant sunshine but that is not the case in Southeast Alaska. relict Load Management and Energy Conservation Load management and energy conservation could be used to reduce power and energy requirements and limit growth in demand. These measures have been tried experimentally in large market areas and have met with questionable success. In the case of the project under study in this report, its primary function is to supply energy to replace existing diesel gen- eration. By applying load management and conservation measures, existing loads could probably not be significantly reduced. Any slowdown in growth rate affected by these measures would only delay the date by which the Project would be fully ab- sorbed by the system and would not significantly affect project economics. Interconnection The nearest large load-center to the project area is Juneau. Interconnection with that system would be imprac- tical at present levels of technology due to the cost of a long transmission line (about 55 miles), an ocean cable crossing, and the low level of consumption in the project area. Other Hydro The earliest published evaluation of hydroelectric power sites in Southeast Alaska was completed by the Federal Power Commission and the U.S. Forest Service in 1947 [1]. That study identified 8 sites on Admiralty Island, one of which was Thayer Creek. In the mid-1960's the Alaska Power Admini- stration made an inventory study of hydro-electric sites in the State of Alaska. As a result of that study three sites, Hasselborg Creek, Thayer Creek, and Kathleen Creek, were indentified on Admiralty Island. In 1977, Robert W. Rether- ford and Associates [2] completed an inventory study which identified the Thayer Creek site as the most promising site to serve Angoon. The Hasselborg Creek site was apparently rejected because the river is an anadromous fish stream. The Kathleen Creek site is farther from Angoon than Thayer Creek. A potential hydroelectric development at Jim's Lake (See Exhibit T-l1) was studied during this present work. That project would be part of a salmon hatchery being considered at the head of Mitchell Bay. The hydroelectric development at Jim's Lake is estimated to cost $25 million at September 1979 price level. Assuming half of this cost would be allocated to the hatchery, the resulting hydroelectric cost would be $31,250/kW for a 400 kW installation. Thayer Creek Tesi) / ) EXH/8/T = : a or - nay Vv g crete (10% Max. Grade) VE Timber Crib barge Loading PY Facility O 00 20 300 400 500 Ley feet Scale HARZA encineeRinc COMPANY AUGUST 1978 8 8 wo 1. te, Dam (| house For Sections A-A, \ B-BEC-C Sée- \) Exabit 7-3. ALASKA POWER AUTHORITY THAYER CREEK PROJECT GENERAL PLAN is estimated to cost $25,000/kW; therefore Thayer Creek was selected over Jim's Lake. A brief map study was made of other potential hydro projects near the project area. The study did not find any site more attractive than Thayer Creek. Wood and Coal Angoon will require a plant of about 500 kW to meet its load over the next 20 years. Wood-waste fired steam turbine generators of that size have not been economically attractive in the past. The most promising wood-waste fired plant in this capacity range uses a gasifier to convert solid fuels containing carbon into a gaseous fuel by means of a thermo-chemical reactor. The gaseous fuel would then be burned in specially equipped conventional diesel units. Such a plant could also use coal or peat as a fuel. Alaska Village Electric Cooperative (AVEC) is currently sponsoring a demonstration project using biomass conversion. Although there is presently no logging operation near Angoon, there are large collections of deadfall timber on beaches near the town. This wood could possibly be harvested for power generation. Also, there is an abandoned coal mine and claim on the south side of Konalku Bay. Other coal deposits have been reported near Passage Point on Mitchell Bay. Both of these areas are about five miles from Angoon. The biomass conversion unit and the equipment required to burn the gas in the existing diesel engine is estimated to cost about $700/kW at September 1979 price levels, including contingencies and engineering. This cost would apply to the equipment required to supply a 500 kW unit. The unit would have to operate on dual fuel (10% diesel oil, 90% gas) and the fuel moisture content could not be more than 30%. At this capital cost, waste-wood fuel (30% moisture) would have to be available at a cost less than $58 per ton and coal at a cost less than $82 per ton in order for the project to be more economical than diesel generation. Those costs assumed: existing diesel units will be used; the interest rate could not exceed 9 percent; and there is no differential fuel escala- tion. The capital cost of the biomass gas fired plant assumes the use of existing diesel engines and does not include the cost of the engine-generator set. The cost of wood in Angoon is difficult to estimate, since there is no local wood processing facility in this town. The Alaska Timber Corporation in Klawock sells dry wood chips for T=—IV—3 $65 per 2400 pound unit, FOB Klawock. Adjusting this cost to an equivalent moisture content (30 to 40 percent) and heat value, equivalent unit weight and adding transportation and handling costs, gives a cost of about $55 per ton delivered in Angoon. In the lower 48 states, wood fuel is generally available to wood-fired plants located in forest areas at a cost of about $15 per ton (40% moisture). Assuming this cost to double for Alaskan conditions, wood fuel should cost $30 per ton if it were available in Angoon. Thus, wood for power generation might cost from $30 to $55 per ton. At this price, the wood fuel might also be suitable for use in biomass conversion units. The wood fuel costs presented in this analysis are at the appraisal level. These costs are sufficiently attractive that a reconnaissance level study should be made for the use of wood-waste and coal in biomass conversion to serve the Angoon areas. An evaluation of direct burning of wood and coal for use in a steam turbine generator should also be included in the study. Diesel At present, the entire load in the project area is met by diesel oil-fired electric generating sets. This is presently the most viable alternative source of generation in the project area. Recent offers received by the THREA for 400-kW diesel electric units averaged about $235 per kilowatt, FOB Seattle, at September 1979 price levels. Including transportation, erection, contingencies, and engineering, the cost of a unit installed in the project area is about $600 per kilowatt. Annual operation and maintenance cost, exclusive of fuel, is estimated to be about $120,000 per year for a plant in the project area. At present (July 1979), diesel fuel in the project area costs about $0.65 per gallon, delivered. This price is expected to increase over the next several months in line with trends in price increases experienced by gasoline. The price of $0.65 per gallon does not reflect the recent 24 percent increase in the reference price of Arabian light crude announced by OPEC in July. To reflect the short term upward pressure on the price of petroleum fuels, a price of $0.80 per gallon is used as the base price of diesel oil in the present economic analyses. Fuel consumption in the project area averages 8.7 kWh/gal, which gives a fuel cost of $0.092/kWh. T-Iv-4 Economic Criteria Certain basic criteria are established for the economic analysis. These criteria define interest rates, fuel esca- lation rates, project life, and period of analysis. Four interest rates, 2,5,7, and 9 percent, are used in the analyses. Differential fuel escalation rates of 0,2, and 5 percent are assumed for diesel fuel. Differential fuel price escalation is the rate at which fuel prices are assumed to escalate over and above the normal inflation rate. The average physical and economic life of the hydroelectric project is assumed to be 50 years and that of the diesel units to be 20 years. The period of study for comparison is taken to be equal to the life of the hydro project, 50 years. Economic Comparison The economic comparison of the project is made using life cycle costing. By this method estimates of costs and benefits are made in the year in which they occur and are then discounted to a common date at a given interest rate. The period of analysis is 50 years. In the analysis, costs and benefits are performed to determine the benefit-cost ratio discounted to January 1, 1980. The results of the analysis are shown on Table T-V-1l. The benefit-cost ratios given on Table T-V-l show that the Project is not economically attractive at any interest rate assuming no fuel escalation. For the purpose of evaluating the Project, a fuel escalation rate of 2 percent is recommended as being representative of future trends. At that rate, the Project would be economically viable at an interest rate of 2 percent. Table T-V-1 THAYER CREEK PROJECT Benefit-Cost Ratios Interest Rate% 2 2) i 2 Fuel Escalation, & 0 0.85 0.49 0.35 0.27 2 1.19 0.63 0.44 0.33 5 2.52 Tuga 0.73 0.49 T—LV—5) Cost of Energy The cost of energy from the Project and the alternative is calculated year by year over the life of each project. The calculations are made assuming a cost of money of 2,5,7, and 9 percent and assuming a differential fuel escalation rate of 2 percent. Normal inflation is assumed at 4 percent per year over the life of both projects. The computations are made assuming the cold storage would not be interconnected. The annual cost of energy includes allowances for amortization, interest, operation, maintenance, administration and insurance. Tax free financing is assumed. The cumulative total cost of energy and the cumulative present worth of the cost of energy were also determined. A discount rate of 8 percent was assum- ed for present worth calculations. The results are shown graphically and in tabular form on Exhibit T-6. As can be seen from the exhibit, the cost of energy from the project is less than that from the alternative after 1988. T-IV-6 Chapter T-V RECOMMENDATIONS AND IMPLEMENTATION Recommendations The economic analysis, presented in the previous chapter shows that the Project is economical at interest rates of 2 percent or less, assuming differential fuel escalation of 2 percent. The project site is located on lands in the Tongass Nat- tional Forest which are being recommended for inclusion in the Wilderness System. Water resource projects are not permitted on Wilderness land except by authorization of the President. Project development therefore would be very unlikely unless the lands were acquired by Kootznoowoo, Inc. (Angoon's Native Corporation). Recommendation for future study of the Project is therefore contingent upon financing and land selection. An organizational framework should be developed as soon as possible to investigate financing alternatives. Discussions should be held with Kootznoowoo, Inc. to de- termine their interest in acquiring the project site. A reconnaissance-level study should be made of the use of wood and coal either as a fuel by conversion to low-Btu gas which can be burned in an internal combustion engine or as a fuel for direct combustion in a boiler to drive a steam tur-- bine. The study should include site specific studies for Angoon and might also include a general study of the use of wood, coal, and peat as a fuel for electricity generation ona regional and statewide basis. If the outcome of the above recommended actions is favor- able, a Declaration of Intention should be filed with the FERC and a feasibility study and, possibly, an FERC license appli- cation should be prepared. Organizational Framework and Financing THREA should be the implementing agency for the Project. THREA is the agency charged with power generation and distribution in Angoon and most of the rural area of Southeast Alaska. THREA also has the possiblity of obtaining low in- terest federal financing for the Project. The Alaska Power T-V-1 Authority might want to serve as an advisor to THREA to provide impetus and guidance during project implementation and to represent the State of Alaska's interest in regional power developement. THREA, with APA support, should make contact with the REA to determine if the Project could qualify for low interest financing. At the same time any possibilities the State or THREA might have for obtaining low interest financing from other sources should be explored. THREA, also with APA support, should obtain a decision from Kootznoowoo, Inc. on land selection. If low interest financing is not available, if land select- ion cannot be made, or if wood or coal fired generation are more attractive than the Project, then future studies of the Project should be deferred. If acceptable financing is available, land selection can be made, and alternative generation is not econ- omically attractive, then the Project should be implemented as described below. Preconstruction Activities A Declaration of Intention should be filed with FERC. Concurrently, a feasibility study of the Project should be started. The scope of the feasibility study should be aimed at satisfying the requirements for an FERC license application, whether or not one will eventually be required. The study should be prepared in close cooperation with state and federal agencies. The exact scope of the study, particularly in relation to environmental studies, will depend on the requirements of the agency under whose jurisdiction most of the affected resources would fall. In this case anadromous fish would be the resource most affected and the Alaska Department of Fish and Games (ADFG) the responsible agency. Also the U.S. Forest Service (USFS) should be included in project planning. Contacts should be made with ADFG and USFS at the time the scope of work is developed and throughout the study. The time schedule for the feasibility study will depend on the baseline date requirements of ADFG. A feasibility study with limited baseline ecological data could be completed in one year's time. At that time a tentative decision on project feasibility could be made and financing and permitting arrange- ments could be initiated. At the same time environmental T-V~2 studies could continue to satisfy ADFG requirements. At the completion of these studies and before award of construction and equipment contracts, an addendum could be issued which would make a final recommendation on project feasibility, and final financing arrangements could be concluded. The Project would be classified as minor (less than 1500 kw) under current FERC regulations. The licensing process could be completed in about one year's time. If the FERC rules that it has jurisdiction, an FERC application could be filed upon completion of the feasibility study by rearranging the material in the feasibility study into license application format. For the purpose of developing an implementation schedule and for the other analyses contained in this report, the case in which an FERC license application would not be required has been used. Design and permits other than FERC licensing could be completed during the final environmental study period to insure that construction and equipment supply contracts could be awarded as soon as possible after the feasibility study is finalized. Implementation Schedule An implementation schedule for the Thayer Creek Project is shown on Exhibit T-7. If organizational arrangements and the feasibility study are begun in the fourth quarter of 1979, the Project could be in commercial operation by the end of 1984. T-V-3 EXHIBIT T-l hy Thayer Creek Watershed Boundary bam Axis Powerhouse New 12.5 VS Transmission \ Line —s . . ANGE: 0 wW yas vbbmariné Cres 519 I se “Se Cj 1 ALASKA POWER BU THORIT. wer 3 7 Sy yew THAYER CREEK PROJECT _ resect Area "GENERAL LOCATION MAP a WARZA ENGINEERING COMPANY: AUGUST 1973 Access Road Ge Original Ground Future Intake Ha or ares not Sound Rock prov Initial Intake be Penstock | Temporary e¢ Lyn Piversion Opening SECTION A-A LOOKING UPSTREAM Scale cl 20 40 Feet pee] Hd seho 4.0'$ Steel Penstock i SECTION C-C WATER CONDUIT Scak 0 /o 20 Feet on | Falls @ Outlet of Canyon, Just U/S of Powerhouse SECTION C,;-C, Scale a 20 40 Feet Diversion Closure Gate "2 Temporar 70'W x7. iz Diversion Conduit EXHIBIT T-3 Training Wall Top of Sound Rock Original Ground. H 2 H, \ SE 3 ‘S Ie rc ioe a SECTION 8-B SPILLWAY Sco Oo Genera tor (200 KW) 30° $ Butterfly Valve Steel Penstock a /é Feet ‘Crane 7§ Ton Capacity ‘Stee/ Column Support for Crane Prefabricated Superstructure (l2'x 50'x 20' High) Fixed Blade Propeller Turbine (28/ Hp) POWERHOUSE TRANSVERSE SECTION Penstock SECTION C2-C2z Scale 9 20 40 Feet CL) Sco 4 8 Feet \eeeieeeeieeeeeee ALASKA POWER AUTHORITY THAYER CREEK PROJECT FROJECT SECTIONS EXHIBIT T-4J ESTIMATE HARZA ENGINEERING COMPANY CHICAGO, ILLINOIS Project, ] hayer Cr eek H yo 6 Date 5S. ple ber [47 Grage / ot. Pooks Structure MMNnéa Estimated by Checked by av ITEM | Quantity Unit Price Amount hs B Zs GS ERCONDUCTOR DAWER HOUSE EXHIBI] 1-4 ESTIMATE HARZA ENGINEERING COMPANY CHICAGO, ILLINOIS hem ITEM Quantity Unit Price Amount MOBILIZATION 4 Const. CAMP | M6 bi | Fi 7001. 1 HIS 001000 ba Dock eS | 06}000 ESTIMATE EXHIBIT T-4 HARZA ENGINEERING COMPANY CHICAGO, ILLINOIS rote Thayer Creek Hydro oon sete er [9 at — os Pages Structure st Co Dainbeiimated by. Checked by. av — ITEM Quontity Unit Price Amount Ss P Y 4 INT, C ‘Ov _700 cY| 48 ZIGC 2 Comn cavation pe eve ee I ‘Lhir WOW} Outi Zo _LF | so qI7Z0 GC 3 OBIS C Zoo ) 5 S Fa | o7 cY| 350 3 Cement & Zoo Cw] AIG 2 ' In-forcin3 37 Zor LBs) fic 0 : t 4 1S LF) 54 Tr rack «ale. / cd farts Lo Ox ock Gol 240 LE] 20 t ty Ini. LS AIO @ WATERCO pUstor SES nstock 22.000 50 oc = ‘tion Joeo cy|_ 42 SO .3 Concrefe ff Supporls ite ic Zs 0 A Cem 60 CwT] /4.10 é 5 ; n¢_ Ste 5 800 18s| 1.10 6 Me olts 1400 LF | 30 43 -7 Clearcin 1 Ac\|7soo sn 0 mon E 1) SGC (ey iiiiig Z Su 2\26 EXHIBIT T-4 ESTIMATE HARZA ENGINEERING COMPANY CHICAGO, ILLINOIS Project_/ ero A cthiled Pelin., Es Structure (YE ri ITEM Quantity Unit Price Amount LOWERHOUSE Rock Excavahon 60 cy | 4% 2/860 ommon Excavation IS cy | 7 [os On AS — ¢ Concrete’ StrucTura| 35 CY | 350 iS Cement a2 loo wT /4,10 16 Reinforciay ‘S is! _ 2000 LBS 10 = Pa ira fee) Lids Floorlf ) B50 SF 8 Prefabricated Bld g ~ £50 SF ed ing AC | “Late © Crane~ Suppert Cofumns L bod lL Sewer 4 Water Treatment [us aef0ed Sub ota | ine |_| 8 IMECHANICAL # ELECTRICAL FauUIP. | 7 LTgebine Verno ) || SE ator ~ x = | Tran Or Aye 2 Units aia 601 O80 Lf E . * Ft ma vip. __| witch ae To bd 1b Be verhotce Tx [Ze EE ubto 4 | - q |ROADS _ | | 9: f OS NM ji 870 Oc] 2 Bench Cut Road OS Mi lr4ebe0 —_kzolooo [| —s Subittal ae ete ee ESTIMATE HARZA ENGINEERING COMPANY CHICAGO, ILLINOIS EXHIBIT T-4 Unit Price gq tae vcer| 6.0 Ml [i606 12 bee, Si ) iy Cabte Crosaina 04 M/ ote LL 4 ' ——. afi MFT a 5 |. FN70/ + Y/OK kit 4 waSRY { | SoAyn a eae pa eG } aeoheseind dene anoen - Eye / 4a SAL LIB/HXFT oes fe ae ie J ‘SeIDy ot. sais alent it Elavetibn iin Feet | t 1 i : 4 a 2 EXHIBIT T-5 _.vheet 20 7 | ON CURVE Au ry! CREEK! PROVECT | 710, DURA os i _FLOY aus eh ALASKA POWER AU? THA feed = --+— Cr. 1 \ ' er. Thay Flow. D urate 0.70 80. 3 ior. { : es ee 06 ft 40 0. ep Bhi 2 SSS Ne Se ase Say ese ieee race ay eno tyre ey Sere aera cc a T raf. Pee tests oo pen bff onal Ene i 17 ' em 5 yate fe Sys we oF Po \ngoon: Fo vette pet een | ® | | § Pred < ‘ le ieee 1 Energy cents i t eee tt 4 ' ! i ? 1 : 1 + t + _ i ' j J i { J iy CE enue cia ee ee oe Ce Sef ee eee s a eeted | [By Ti i i { t i | i i { | a oe] eeees ee SE earns ae Creek Hydro’ 7 EXH/B/T 7-6 eae Seen ure ed ih { \ | | | {3 } f i { I ee i 1330 il Marea. ae { 1 het ta be ee 2005. . | regen ae skA POWER AUTH ITY. eer : gone AYER CREEK PROJECT Lees epee one eerer a Pais COST OF MONEYS REFERENCE MATE YEAR 1985 1986 1987 1988 1989 1990 1994 1992 1993 1994 1995 1996 1997 199R 1999 2000 2004 2202 200 2004 2005 2006 2007 20c8 2009 2010 20%1 eci2 2013 20tu 2015 2016 2017 2018 2019 2crg acy 2022 2023 2c2u 2526 2026 2027 2028 eceg ectn ent 2cse 2033 2c3a FIKED COSTS 367, 367, 367, 367, 367, 367, 367, 367, 367. 3o7. 3o7, 367, 367, 307, 3oT, 367, aoa, 404, wou, Os, aoa, GO, od, aou, uod, uo4, 4o4, uda, Gnu, aoa, ou, Goa, uo4, aou, aoa, wos, aos, uo4, wou, 40a, ane, “os, aod, Sie. Sie, Ste. Sie. 5i2. Si2. Sie. Own costs 715 74, 77. 80, 83, Be, 90. 93. 97, 101, 105, 109, 113. 114, 123, 128, 133% 138, 144, 149, 155. 161, Loa, 17S. 182, 189, 196, 204, ete. eel, asc, 239, 249, 259, 269, 250, eat. 302, 315. 327, 340, 354, 368, 383, 398, Gia, 430, GoR, cee, 484, INFLATION RATES JANUARY 1980 THAYER CREEK PROJECT 2040 TOTAL u3Be u4te ude ude uS0e U5de ud%e ub0e Ubke UOBe u72e U7be u80~e 4856 49068 u95e S37. S4ae 54Bs 5536 5596 S656 57260 579 586. 5936 6006 60B. bloe 6256 6346 6436 6536 6536 6736 6846 6956 7066 7198 Wie Wade 7586 7720 RIS. 9106 9266 9426 9606 9766 9966 HYDRO FUEL ESCALATION RATE= .020 ALL COSTS IN & 1000 ENERGY GENERATED Mah 1234, 1253, 1271. 1290, 1310, 1329, 1349, 1370, 1390, 1411, 1432, 1454, 1475, 1496, 1520, 1543, 1566, 1589, 1613, 1637, 1662, 16087, 1712, 1738, 1764, 1790, 1817, 1645, 1872, 1900, 1929, 1958, 1987, 2017, 2047, 2078, 2109, 214i, 2173, 2205, 2236, e272, 2306, es4i, 2376, e4uii. 2448, 2ubu, 2522, 2559, Cost OF ENERGY CENTS/KWK 35.5 35.2 34,9 34,6 34,4 34,1 33,8 33,6 33,4 33,2 33,0 32,8 32,6 32,4 32,2 32,1 34,3 34,1 33,9 33,8 33,6 33,5 33,4 33,3 33,2 33,1 33,0 33,0 32,9 32,9 32,9 32,8 32,8 32,8 32,9 32,9 32.9 33,0 33,1 33,2 33,2 33,4 33,5 38,2 38,3 38,4 38.5 38,6 38,8 38,9 CUMULATIVE TOTAL 438, 679, 1322, 1769, 2219, 2672, 3129, 3589, 4OS3. 4521, 4993, 5469, 5949, G34, 6924, 7418, 7955.5 Bu97, 9045, 9598, 10157, 10723, 11295, 11873, 12459, 13052, 13652, 14261, 14877, 15502, 16136, 10779, 17431, 18094, 18767, 19450, 2014s, 20652, 21579, 22301, 23045, 23803, 24575, 25470, 20380, 27306, 28248, 29208, 30185, 31182, PRESENT WORTH 276, 257, 240, 223, 208, 194, 181, 169. 158, 147, 138, 129, 120. 112, 105, 98, 99, 92, 86, al, 76, Th, 6b, b2. 58, 55. Ste ub, us, ae, 40, 37, 35, 33, 3Le 29, 27, 26, 24, 23. 22. 20, 19, el. 19% 18, 17. 16. 15. 14, DISCOUNT RATES ,080 CUMULATIVE Pai, 276, 533. 7736 99 be 1205. 1399, 1580, 17506 1908. 20556 2193. 23246 2442, 25546 26596 27576 2856, 2948, 3035, 3ilbe 31916 32626 3328, 3390. 3449, 35036 355u. 3602 3047, 36906 37296 37to. 3602. 3a3u4, 38656 38956 3922. 3946, 39726 39956 4017. 4037. 4OSbe GOTT. UO9be6 itd, 41326 4146. GYO3. G178. 6 9 Zz 4984S QL LIGHXF HARZA ENGINEERING COMPANY THAYER CREEK PROJECT HYORG COST OF MONEYS .056 INFLATION RATES 040 FUEL ESCALATION RATE& ,.020 DISCOUNT RATES ,080 REFERENCE DATE s JANUARY 1980 ALL COSTS IN $ 1000 FIXED Oem FUEL ENERGY Cost OF CUMULATIVE PRESENT CUMULATIVE Year costs costs cost Total GENERATED ENERGY TOTAL WORTH PAW, Man CENTS/KWh 19RS 046, M1, W176 1234, 58,1 717, uS2, aS2, 1986 o4o, 74, 7206 1253, 57,5 1437, 420, 872. 1987 o4o, 77. 723. 1271, 56,8 2159, 390, 1262, 1988 646, BO. T2oe 1290, 56.2 2885, 363, 1625.6 1989 646, 83, 7296 1310, 55,7 So14, 336, 1963, 1990 bub, Bo, 7326 1329, 55.1 4346, 314, 2277 1994 646, 90. 3b. 1349, 54,5 soee2, 292, 25609. 1992 eds, 93. 73%. 1370, 54,0 5821, 272. 2641.4 1993 o4e, 97, 7436 1390, 53.4 oSou, 253. 3094, 1994 646, 101, 7476 1411, 52.9 USNs 235. 3329, 1995 646, 105, 7516 1432, 52,4 8062, 219, 3548, 1996 646, 109, 7556 yas, 51.9 8817, 204, 3752. 1997 646, 113, 7596 1475, Se) 9576, 190, 3942, 1998 bue, ia, 766 1498, 51,0 10340, 177, G119, 1999 . 646, 123, 76%. 1520, 50.6 11109, 165, 4264, 2000 o4o, 125, 77u. 1543, 50.1 11682, 154, UG3R, 2on4 710, P3370 B43. 1566, 53.8 12725, 155, 4593, 2002 710, 136, R4uB. 1549, 53,4 13573, tad, G73B, 2003 710, laa, asc. 1613, 52,9 14427, 135. 4872, 2004 710, 149, ASG. 1637, 52.5 15286, 125, 6998, 2005 710, i55, ROSe 1662, 52.1 16151, 117, S115. 2006 710, 161. B76 1687, 51,7 17023, 109, S22u, 2007 710. 168, R7Be 1712, Si.3 17901, 102, 5325. 2008 710. 175, RBS. 1738, 50,9 18785, 9S, 5U206 2009 710, 182, BV26 1764, 50,5 19677, 89, 5509. 2010 710, 189, R996 1790, 50,2 20576, 83, S592, 2011 710, 196, - 906. 1817, 49,9 21482, 77. 560% 2012 7105 204, 1b. 1645, 49,6 22397, 72. S741. 2o1y 710, ate. 9226 1872, 49,3 23319, 67. S808, 2018 710. CONG 9316 1900, 49,0 s 24250. 63, S671. 2015 710, 230, a4o. 1929, 68,7 25190. 59, 59306 2016 710, 239, 94% 1958, 46,5 26139, SS. 5985, 2017 710, 249, 9596 1987, 48,2 27097, St. 6037, 201R * 710. 259, 9696 2017, 48,0 28066, ub, 6085. 2019 710, 269, 97%. 2047, 47,8 29045, 45, 61306 2020 710, 280, 9906 2078, 47,6 30034, 42, 61726 2024 710, 291. 190L6 2109, 47,5 31035, 39, 6212.6 Gy eve? 710, 302, 1ol2e 2141, 47,3 320u8, 37. 6249, > m 2023 710, 315, 1025s 2173, 47,2 33072, 35, 6283. th >< 2024 710. 327, 1037. 2205, 47,0 34109, 32, O31b. at 2025 M10. 340, 10506 2238, 46,9 35159, 30, 6346, ®o & 2026 710, 354, 1o646 2272, 46,8 36223, 29%, 6375.6 “’ OB 2027 710, 368, 1078. 2306, 46,7 37301, 27. 6402 > 2028 710, 3A3, 10936 234i, 46,7 38394, 25, 64275 UN 2029 B94, 396, 12926 2376, Sa,u 39666, 28, ouSu, QO 2030 Boa, ata, 1308. 24, 54,2 40994, 26, 6486, > MN 2031 B94, uo, 1524. 2448, Su,t 42316, 24, 050G, ’ 2032 894, &GR, 13626 2464, 54,0 uso60, 23, 6527. \O 6\ 2933 Bu, S66. 1360. 2s2e, $3.9 uS019, 2k. OSGR, 203u acu, ues, 1378. 2559, 53,8 e394, 26. 6568, LIARZA IMOMEFE OS COMPANT COSY OF MONEYS YEAR 1985 196 19A7 1988 1989 1999 199) 1992 1993 1994 1995 1996 1997 199R 1999 2000 2004 2002 2003 20.4 2005 2006 2007 2008 2009 2010 20t4 2012 2013 2014 2015 2916 2017 2018 2019 2020 2024 2022 2023 2024 2025 2026 2027 2028 2029 2030 2034 2032 2933 2034 869, 869, 869, Bod, 869, 869, 869, B69, B69, 899, B69, 869, ROG, 869, 69, B69, 954, 954, 954, 954, 954, 954, 954, 954, 954, 954, 954, 954, 954, 954, 954, 954, osu, 954, 954, 954, 954, 954, 954, 954, 954, 954, 954, 954, Soir AS? 6 1197, 1197, 1197, aeLiGi77.) Ow costs 71. 74, 77. 60, 83, Bo, 90, 93. Sia 101. 10S. 109, 113. 1148, 123, 126, 133, 134, laa, 149, 155, 161, 168, 175.0 $82. 189, 196, 204, 212. 221, 250. 239, 2u9, 259, 269, 280, 29ste 302, Silaie 327, 340, 354, 3645, 383, 396, 414, 430, Gus, S66, GBu, INFLATION RATES REFERENCE DATE = JANUARY 1980 FIXED costs FUEL cost THAYER CREEK PROJECT 2040 ToTAL 9406 G43e 946s 9496 9526 9556 9598 9626 9066 9708 Q74e OTB, 982. 9576 9926 9976 1087. 19926 10986 1103. 1409. 11156 14226 1129. 11366 11436 1450.6 1458. 11666 14756 1164. 11936 12036 Lolde 12236 La3de 12456 12566 1269. 12816 12946 1308, 1322. 13376 1595.6 lolie 1627s 16456 1663.6 1o51e HYDRO FUEL ESCALATION RATES 029 ALL COSTS IN $ 1000 ENERGY GENERATED Man 1234, 1253, 1271, 1290, 1310, 1329, 1349, 1370, 1390, 1411, 1432, 1454, 1475, 1496, 1520, 1543, 1566, 1589, 1613, 1637, 1662, 16057, 1712. 1738, 1704, 1790, 1617, 1645, 1672, 1900, 1929, 1958, 19875 2017, 2047, 2078, 2109, 214i, 2173, 2205, 2238, 2272. 2306, 2341, 237o, 24it, 2448, 2464, 2522, 2559, Cost OF ENERGY CENTS/KWh 7o,2 75,3 74,4 73.5 72,7 71.9 71,0 70,3 69,5 68.7 68,0 67,3 66,6 65,9 65,2 64,6 69,4 68,7 68,0 67,4 66,7 66,1 65.5 64,9 64,4 63,8 63,3 62,8 62,3 61,8 61,4 * 60,9 60,5 60,1 59,7 59,4 59,0 58,7 58,4 58,1 57,8 57.6 57,3 57.3 67,1 66,8 66,5 66,2 65,9 65,7 CUMULATIVE TOTAL 940, 1683, 2828, 3777. 4729, S664, 66u3, 76056 BS71, 9541, 10515, 11493, 12475, 13462, 144Sa, 15450, 16537, 17629, 16727, 19630, 20939, 22055, 23177, 24305, 25441, 20584, 27734, 26893, 30059, 31234, 32418, 33611. 34513, 36626, 37249, 36482, 39727, 40984, 42252, 43533, 44827, 46135, 474S7, wa79g4u, 59389, 52000, $3027, $5272, 56934, Sbo16, PRESENT WORTH S92, 550, Site u75, Gul, 410, 361. 354, 329, 306, 264, 264, 246, 229. 213. 198, 200, 186, 173, 161. 150, 140, 130, lel. 113, 105, 98, G1. 65, 79, 74, 69, 65. 60, So, 53, 49, Ub, 43, GO, 38, 356 33, 3ie 34, 32. 30, 26, 26, 24, DISCOUNT RATE ,080 CUMULATIVE Pym, 592. 1142. 16053. 2128. 2569. 2978, 3359, 37136 4042. U3uB, 4os2. GBI. $142, S370 5583. S781. 5981, O17, 6340. ©5016 66516 6791.6 6921. 7042. i256 72606 7358. 74506 75356 Told. 7669, 77586 78226 1883.6 7939, 719916 BOUL, 8086, 8129, 81706 B2076 6242, 8275.6 6306» 8340, 6372. 840%. 6429. 8455.6 8460, 6 fo ¢ 498s 9-L LIGIHXY HARZA ENGINEERING COMPANY COSY OF MONEYS REFERENCE DATE YEAR 1985 1986 1987 19RR 1989 1990 1994 1992 1993 1994 1995 1996 1997 1998 1999 2600 2004 20%2 2003 2004 2005 2596 2007 2008 2909 2010 2011 2012 203 eo1a 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2079 2030 2031 2032 2033 2034 FIXED costs file, 1i1e, 1i1e, 1it2, iiie. ~ . NUNN MN . oe ee eee 0+” costs TAs Ta, tha 80. 83, Bo, 90, 93. 97, 101, 1cs, 109, ise 118, 123. lee, 133. 138, 144, 149, 155. 161. 164, 175. 182, 189, 1Se, 204, 212, eet, 230. 239, eud, el. 269, 280, eek, 302, S15 LieUG 340, 354, 36, 383, 398. aye, u3o, aoa, Gob, 4Ba, INFLATION RATES JANUARY 4980 FUEL cost THAYER CREEK PROJECT 0040 TOTAL 1183. 1166.6 11896 11926 11956 1198. 1202. 12056 1209. 12136 1217.6 12216 1225-6 1230. 12356 1240. 13526 1357. 15636 13686 13746 1380. 1387, 1394, Lute 1408. 14156 1u2de ludte 1440. 1449. 1u5Be 1u6b. 1u78e 1488. 10996 15106 15216 1534. 1546.6 1559. 1573. 1587. 16026 19226 19386 1654.6 19726 19906 20066 HYDRO FUEL ESCALATION RATES .020 ALL COSTS IN $ 1000 ENERGY GENERATED Mah 1234, 1253, 1271, 1290, 1319, 1329, 1349, 1370, 1390, 1411, 1432, 1454, 1475, 1498, 1520, 1543, 1566, 1589, 16013, 1637, 1662, 1687, 1712. 1738, 1764, 1790, 1817, 1845, 1872, 1900, 1929, 1956, 1957, 2017, 2047, 2978, 2109, 2141, 2173, 2295, 2236, 22726 2306, 2341, 2376, 24ait, 2aue, 2484, 2522, 2559, cost OF ENERGY CENTS/KWH 95,9 94,7 93,5 92,4 91.2 9041 89,1 88,0 87,0 86,0 65,0 84,0 83,1 62,1 61,2 60,3 66,3 65,4 84,5 63,6 62,7 81,8 61,0 60,2 79,4 78.6 77,9 77,2 76,5 75,8 75,1 “74,5 73,9 73.3 72,7 72,1 71,6 71,1 70,6 70,1 69,7 69,2 68,8 68,4 80,9 60,4 79,8 79,4 78,9 78,5 CUMULATIVE TOTAL 1163, 2369, S556 4749, Souq, T1de2, 8344, 9549, 10758, 11971, 13186, 14409, 15634, 16664, 16099, 19338, 20690, 220467, 23410, 24778, 26152, 27533, 28920, 39313, 31714, 33122, 34537, 35961, 37392, 36832, 40261, 41739, 43206, acead, 46172, 47670, 49180, $0702, S2e35, 535731. $5340, $6913, 56500, 60102, 62026, 63962, S916, 67688, 69877, 71886, PRESENT WORTH 745, 692, ou2, S96, 553. si4, 4776 443, die, 382, 355. 330, 307, 285. 2656 eho, 249, 23k, 215, 200, 186, 173, 161. 150. 139, 130, 12t. ii2, 10S, 97, De 85. 79, 73, 68, 64, 60, So. Se. a8, US, 42, 39, 37. ut. 38, 36, 33, 31. 29, DISCOUNT RATES ,080 CUMULATIVE Pay, 7456 1437, 20796 2676.6 3229. 3743, 42206 Weed, S075. SUS7. S812. o142, 6449, 6734, 6999, 72456 TU9G, 77256 7940. 8140, 8326, BudA, 665%, 6809, 6948, 9077. 9198, 93106 9615, 95126 9003.6 9668, 97bb. GBU0, 9908, 9972. 10032. 10067, 10139. 10188, 10233, 10275. 103156 1035), 10392. 10431. 104666 10500, 10531. 10560. 6405 4904S 9-L LIGIHXF HARZA ENGINEERING COMPANY ) f y THAYER CREEK PROJECT NIESEL ALTERNATIVE COST OF MONEYS (020 INFLATION RATES 6040 FUEL ESCALATION RATES ,020 DISCOUNT RATE= ,080 REFERENCE DATE = JANUARY 1980 ALL COSTS IN $ 1000 FIXED Cem FUEL ENERGY cost OF CUMULATIVE PRESENT CUMULATIVE YEAR cosTs costs rast TOTAL GENERATED ENERGY TOTAL WORTH Par, Mil CENTS/KWH 1985 0. 213, fol, 3746 1234, 30,3 374, 235, 235, 1986 oO. 22. 173, B9U6 1253, 31,5 768, 230. Uobe 1987 oO. 230, 186, ulee 1e7t, 32,7 1164, 2256 6906 1988 oO. 235, 201, 40e 1290, 34.1 1624, 220, 9106 1989 0, 249, P16, uous 1310, 35,5 2088, 215, 1126. 19909 0. 259, 232, UIte 1329, 36,9 2579, 210, 1336. 1994 0. 269, 250, 519, 1349, 38,4 3098, 206, 1542. 1992 0. 280, 269, S4By 1370, 40,0 Bodo, 202, 174u, 1993 oO. 2%, 2289, S806 1390, 41,7 4227, 197. 1944, 1994 oO. 303, att, olbe 1411. 43,5 4640, 193, 21356 1995 0. 315, 335, 64% 1432, 45,3 5490, 190, 232d, 1996 Oo. 327, 360, 6876 1454, 47,3 o177, 186, 2510.6 1997 30, Bun, wal, 7566 1475, 51,4 6935, 190, 2700. 1998 30, 354, “17, BOLe 1498, 53,5 7735, 186, 28856 1999 30, 368, uue, B47. 1520. 55,7 6582, 182, 3067. 2000 30, 383, ues, RISe 1543, 56,0 Qu77T, 178, 3245, 2001 30, 398, 519, Oates 1566, 60,5 10425, 174, 3019, 2002 30. ic, 559, 1n035 1589, 63,41 11427, 171. 359%. 2003 30. ayy, 601, 1oe2e 1613, 65,8 12489, 167. 3757.6 200g 30. aus, 647, 1924, 1037, 68,7 13413, 1o4, 39256 2005 30, doe, 496, 14916 1662, 71.7 1460S, 161, 4082, 2906 30, uaa, 7uB, 12036 1667, 74,9 16068, 158, W240. 2097 30, Sou, ROS, 1339. 1712. 78,2 17407, 155. U396, 2008 30. Sau, RO6, 14206 17386, 81,7 18627, 1S2,. USB, +2009 30, 56S, 932, 15076 1764, 65,4 20334, 150, 4698, 2010 30. 567, 1903, 16906 1790, 69,3 21933, 147, Gaus, ent 30, 589, 1079, 1698. 1817, 9355 23632, 145, 4990, 2eote2 30, 613, 1161, 1R0U, 1645, 97,8 239435, 142, Si32e 2013 30, 637, 1249, 1916. 1872, 102,4 27352, 140, 52720 201g Bo, 663. 174d, 2037s 1900. 107,2 29389, 138, S106 201s 39. OBS, luse, 21656 1929, 112,3 31554, 136, 5545, 2016 sO, 717, 1555, 23030 1952, 117,46 33856, 134, 5679. 2017 99, Tho, 1A74, 251K. 1987, 126,7 36375, 135, SEld, 2018 99, T76. Trot, 2675s 2017, 132.6 39050, 133, SOUT. 2019 99, 807, 1937, 2ad3, 2047, 138,9 41693, 13te 607B. 2020 99, 39, 2naku, 3Bn226 2078, 145,40 aegis, 129, 6207. 2024 G5, AT2, 2742, Bailde 2109, 152,4 48128, 127. 6334, Y) h 2022 $9, 907, 2u13, 3ulGe e14t, 159,7 Sisu7, 1256 OUSRB, > 2023 99, 944, 2596, 36368. 2173, 167.4 55186, 1235. 6582, r x 2624 99. al, 2793, BAT3e 2205, 175,6 $9059, Lele 67036 % t 2025 99, 1021. 305, 4124. 2238, 164,2 63183, 120, 6823, 5B 2026 99, 1061. 3233, 4x9 2272. 193,46 67577, 116, OFUL, * 2027 99, 104, 378, 46816 2306, 203,40 72258, 116, 70576 Rar 2028 99, 11GA, 3742, UGB, 2341, 213,1 77247, 1156 71726 \ N 2029 99, 1194, sn26, S3l%e 2370, 223.9 82566. 113, 7285. 9 2030 99, 1242, 4%32, So7de 241i, 235,2 86259, 112. 7397, NS N 2031 99, 1291, dhol. o0Ste 2448, 247,2 94290, 11le 7508, ' 2032 99, 1343, Sota, 6U5b. 2484, 259,9 100746, 109. Tel?e \o N 2033 99, 1397. 53955 OAM 6 2522, 273.3 107637, 108, 77256 2034 994 1453, Saou, 73566 2559, 287,44 114993, 107, 7B326 HIARZA ENGINEERING COMPANY COST OF MONEYS YEAQ 1985 1986 1987 1988 19A8Qq 1990 1994 1992 1993 1994 1995 1996 1997 1998 1999 2000 2004 2cn2 2003 2004 2005 2906 2097 2008 2009 2010 2013 Pole 2013 2o1a 2015 2916 2017 2018 2019 2020 2024 2022 2023 2924 205 2026 2027 202R 2029 2030 2031 2032 2033 2034 Or cosTs 213, 22). 230, 239, 249, 259, 269, 280, 2o1, 303, 315, 327, 340, 354, 3oR, 383, 398, aia, asi, aur, doe, Bu, Sou, Seu, sus, S67, 589, 613, 637, 663. 689, Ji7, 746, TTo. 807, 639, 872, 907, Qu4, 981, 10214, 1061, 1104, 1146, 1194, 1242, 1291, 1343, 1397, 1453, INFLATION RATES REFERENCE DATE = JANUARY 1980 FIXED cosTs FUEL Ost ol, 173, 186, aot, aie, 232. 250, 769, 289, Vite 335, oO, 387, oi7, aaa, 4B3, 519, 559, 601, 4u7, 496, 748, aos, Rob, 932, 103, 1A79, 146t, 1249, 144, 1ags, 1555, 1a74, LAO, 1o37, 2nk4, 2242, 2ui3, 2556, 2793, 3005, 3933, 3u7a, 3742, 4n26, 4332, chol, Sais, $395, Sao4, é THAYER CREEK PROJECT nIESEL 2040 ToTal B7Ue we Ulbe 440s USue uMte 51%. 548. 5806 bide 6490 6876 708. Rlie a576 a056 957s 1ol3e 10726 14346 12016 12736 13496 14306 1517. 16106 1708. LALds 19266 20476 2475s 23130 2549. 27066 2A7U. 30536 32456 3u500- 36698 3q0U. 44556 UHede 47126 50206 $3506 S70ue 60826 6uET. 69226 73876 ALTERNATIVE FUEL ESCALATION RATES ,020 ALL COSTS IN $ 1000 ENERGY GENERATED Mah 1234, 1253, 1271. 1290, 1310, 1329, 1349, 1370, 1390, 1411, 1432, 1454, 1475, 1498, 1520, 1543, 1506, 1589, 1613, 1637, 1662, 1687, 1712, 1738, 1764, 1790, 1617, 1645, 1872, 1900, 1929, 1958, 1987.6 2017, 2047, 2076, 2109, 24st, e173, 2205, 2236, 2272, 2306, 2341, 2376, 2411, 2448, 2uea, 2522, 2559, cost OF CUMULATIVE ENERGY TOTAL CENTS/KWH 30.3 374, 31,5 768, 32,7 1184, 34,1 1o2u, 35,5 2088, 36.9 2579, 38,u 3096, 40,0 3646, 41,7 4227, 43,5 4840, 45,3 5490, 47,3 6177, 52,0 6945, Sus 77556 50,4 Bol2, 58,7 9517, 61,1 10475, 63,7 11467, 66,4 12555, 69,3 13693, 72.3 14695, 75,5 1616R, 73,8 {7517.6 82,3 16947, 66,0 20464, 89,9 22073, 94,0 23782. 98,3 25595, 102,9 27522, 107,7 29569, 112,8 3i74a, 418.1 340Sd, 126,3 36606, 134,2 393t2. 140,40 42166, 146,9 45239, 153,9 48GB, 161,2 51933, 1608,9 55003, 177,0 59557, 185.6 oicae, 194.7 630487, 204,3 72799, 214,5 77819, 225.2 83169, 236,5 80873, 248.5 94955, 2ol,t 101442, 274.5 108364, 288.6 115751. PRESENT WORTH 235, 230, 225, 220, 215, 210, 206, 202, 197, 193, 190. 186, 192, 188, 184, 180, 176, 172, 169, 166, 162, 159, 156, 154, 151. 148, 146, 143, 141, 138, 136, 134, 137, 135, 1320 130. 128, 126, 126, 122, 121. 119.6 117. 116, 114, 113, Lil, 110. 108, 107. OISCOUNT RATES ,080 CUMULATIVE Paw, 2356 Ub6. 6906 9106 11266 1336. 1542. 17a, 194, 21356 232u6 25106 27026 28906 3074. 325U, 34306 36026 37716 39376 4099,% 4259, 4U1S6 45056 47196 UROT, S013. SiSee S297. SU35, SS716 5705. S642, SS77. 610% 62396 6357, CUGT, bbls 6760, ©8690, 6O79. 104 be 72i26 7326s TOG, 75506 T6E06 7T7O0B. 7875. 642 2 fP7YS 2-L LIGIHXT HARZA ENGINEERING COMPANY COST OF MONEYS ,070 FIXED YEAR costs 1985 0. 1926 On 1987 Oo, 198R 0. 1989 0. 1999 Oo. 1994 0, 1992 Oo. 1993 0, 1994 0. 1995 0, 19% 0. 1997 a7, 1998 47, 1999 a7, 2000 GT. 2004 One 2002 67, 2003 47, 2004 47, 2005 47, 20% 47, 2097 47, 2008 47, 2009 Gy, 2010 47, 20'4 47. 2012 47, 2013 47. 2054 ay, 2015 a7, 2016 47, 2017 154, 2018 154, 2019 154, 2n29 154, 2021 154, 2022 154, 2023 154, 2o2u 154, 2025 14, 2026 156, 2027 154, 20248 154, 2029 154, 2030 154, 2931 154, 2032 154, 2033 154, 2034 154, Oem costs 233. 221. 230, 239, 249, 259, 209, 280, 291, 303, 315, sara 340, 354, 368, 383. 398, aia, esi. gua, 4o6, 46a, Soa, S24, Sus. 567, 569, o13, 637. 663, 689, 717. 746, 776. 807, 839, 672, 907, Sua, 981. 1021, 1Col, 1104, 1148, 1194, teue, 1291, 1343, 1397, 1453, INFLATION REFERENCE DATE = JANUARY 4080 FUEL cost fol. 173, 186, 2016 216, 23e, aso, 269, 7a9, Stl. 335, 360, WET, ait, aus, a53, 619, 559, s01, a4u7, 696, 748, aos, R66, 932, 103, 1979, 1161, 1249, 1yaa, tude, 1555, 1A74, 1Aa01, 1937, 284, 2rd, 2013, 2596, 2793, 305, 3233, 3u78, 3742, 4n26, 4332, Sool, Soi4, 5395, SAO4, RATES YMAYER CREEK PROJ nTeset 2040 TOTAL 37c. 3b. ulbe 440s UOus uFte S19. 54B. S806 blue 649. 637s 7756 Bla. ROUe 9l2e Qb46 19200 1079. 1141. 1208 12806 13566 1u3?e 15246 L6d7: 1715e 1a2te 19336 20546 2162. 23206 25736 27306 2A98. 30776 32696 Bulue 35936 3028, G179% GUSBe U73b6 Sn4de Stlde S72B6 61966 oslte G46. Tale ALTERNATIV FUEL ESCALATION RATES 2020 ALL COSTS IN & 1000 ENERGY GENERATED MnH 1234, 1253, T27i. 1290, 1310, 1329, 1349, 1370, 1390, 1411, 1432, 1454, 1475, 1498, 1520, 1543, 1566, 1549, 1613, 1637, 1662, 1687, 1712, 1736, 1764, 1790, 1617, 1845, 1872, 1900, 1929, 1958, 1987, 2017, 2047, 2078, 2109, 2141, 2173, 2205, 2238, 2272, 2306, 234i, 2376, 2411. 2448, 2ue4, 2522, 2559, Cost OF CUMULATIVE ENERGY TOTAL CENTS /KAH 30,3 374, 31.5 768. Sent 1164, 34,1 1o24, 35,5 2088, 36,9 2579, 38,4 3096, 40,0 3oub, 41,7 4227, 43,5 4840, 45,3 5490, 47,3 : 6177, $2.5 6952, 54,6 7769. 50,8 6633, Set 9545, 61,6 10510, 64,2 11529, 66,9 12608, 69,7 13749, 72,7 14958, 75.9 16238, 79,2 17594, 62,7 19031, Boa 20555, 90,3 2217. 94,4 23687, 98,7 25707. 103,3 27641, 108,1 29695, 133,1 31877, 118,5 34195, 129,5 360779, 135,4 39500, 1414,5 42398, 143,14 45475, 155,0 GB743, 162,3 $2217, 170,0 S59i1, 178,41 59839, 166,7 64018, 195,8 68467, 205,48 73203, 235.5 76247, 226,2 83621. 237,5 89349, 249.5 95455, 262,1 1014966, 275,4 108912, 289.6 116323, PRESENT WORTH 235. 230, 225, 2206 215, 210, 206, 202, 197, 193, 190, 186, 194, 189, 165, 161, 177. 174, 170, 167, 163, 160. 157. 154, 15t, 149, 146, ia4, 141, 139, 137. 134, 138, 134. 133, 131. 129, 127. 125, 123, 12k. 119, 118, 116, 115, 113, 112. 110, 109, 108, DISCOUNT RATES ,080 CUMULATIVE Pom, 235. dob, 690% G10. 1125. 1336. 1542. 1744, 1944, 21356 2324, 25106 270d, 2693, 3079, 326%. 3437, Bolle 378i, SOUR, Gitte “2716 GU2Be 45e3e Gr3u, Gass, 5029. Si73. S3id, SuSde 5S69. S72u, S826 5998, O13t. 62625 O3916 6518. E43, O7bb66 68458, 1007, 71236 T2446 7356. T4695 7580, 7690.6 1799.6 7907, 6 Jo 9 feeys Q-L LIGIHXF LARZA ENGINEERING COMPANY Cast CF “CNEYS REFERENCE NATE YEAR 1985 1986 1SA7 1988 1989 1990 1994 1992 1993 1994 1995 1996 1997 1998 1999 2000 2004 2002 2003 2004 ecns 20% 2007 2008 2009 2010 2co11 2082 2013 2014 2015 2ct6 2017 2018 2019 2020 2024 2022 2923 2024 2025 2026 2027 2728 2029 2030 2c34 2032 2033 2034 FIXED costs 2990 = JANUARY O+n costs e136 eet. 230, 239, 249, 2596 269, 2A0, 2ui. 303, 315% 327. 340, 354, 368, 363, 398, 4i4, a3, qua, 4oo, aaa, Sou, S24, 545, 567. 589, 613, 637, 063, 689, T17 6 T4o, Tlo. B07, 839, 872, 907. 944, ORL. 1021, 1061, 1104, 1148, 1194, 1242; 1291, 1343, 1397, 1453, INFLATION 1980 FUEL cost tole 1736 186, ant. 216, 232, 250, 269, 269, Bil, 335, 360, RAT, ai?, 4ua8, oat, si9, 559. aol, 447, 496, TUR, aos, REO, o32, ino3, 1979, Tot, 1349, 134d, luge, 1555, Lard, 1a01, 1937, 2na4, 2242, 2ui3, 2596, 2793, 3705, 3233, 3478, 3742, un26, 4u32, Goel, Soi4a, 5395, Saou, RATE= nie +040 TaTal wd, BPMs ulbe 440. Uode 4916 519. 546. 58%. blue 6496 6876 7796 R226 ROA, Qlbe QOB. 19246 10836 11456 Y2126 Lahde 1360. 1u4te 15286 16216 17196 1R256 19376 20586 21866 252d, 25556 27426 20106 389%. 37816 34866 37056 39406 4196 ube U746, 5056. S38be0 5740.6 6,18. 6523. 695B. 7U236 2 CREEK PROJEC VE ALTERNATI FUEL ESCALATION RATES ,020 ALL COSTS IN $ 1000 ENERGY GENERATED Mia 1234, 1253, 1271, 1290, 1310, 1329, 1349, 1379, 1390, 1411, 1432, 1uS4, 1475, 1498, 1520, 1543, 1560, 1589, 1613, 1637, 1662, 1687, 1712. 1738, 1764, 1790, 1817, 1845, 1872, 1900, 1929, 1958, 1987, 2017, 2047, 2078, 2109, 2141, 2173, 2205, 2258, 2272, 2306, 2341, 2370, 2411, 2448, 24ueu, 2522, Doo. Cost OF ENERGY CENTS/KWh 30.3 31,5 32,7 34,1 35.5 36,9 38,4 40,0 41,7 43,5 45,3 47,3 52,8 Su,9 57.1 59,4 61,86 64,4 o741 70,0 ea9 Toei 79,4 82,9 66,6. 90,5 94,6 98,9 103,5 106,3 113,3 118,7 130.1 136.0 142,14 148,7 155,6 162,8 170,5 178.7 187,2 196,3 205,9 216,0 226,7 238.0 250,0 262,6 27559 290.0 CUMULATIVE TOTAL SU 768, 11e64, lo2d, 2088, 2579, 3098, 3o46, 4227, UBUuO, 5490, 0177, 6956. 7777. @ouS, 9561. 10530, 11553, 12636, 13781, 14994, 16278, 17638, 19079, 20007, 22227, 23947, es77t. 27709, 29767, 31953, 34276, 368o2, 39604, o2esia, 45603, 46883, $2369, 56075, 60015, 64206, 68667, 73415, 76471, 83557, 89597, 95715. 102236, 109196, 110619, OISCOUNT RATE= ,080 PRESENT WORTH 235, 230, 225. 2206 215. 210. 206, 202, 197, 193, 190, 186, 195, 190, 166, 162, 178, 174, 171, 167, 164, 161. 158, 155. 152, 149, 146, 144, 142, 139, 137, 135, 139, 136, 134, 132, 129, 127. 125, 123, 122, 120, 118, 116. 115, 113, 112, 110. 109, 108, CUMULATIVE Paty 2356 Uobe 6906 9106 11266 1336.6 1542, 1744, 1944, 21356 2324. 25106 2705.6 28956 3081. 3263, 3442, Bolbe 3787.6 3954, G11Be W279, Gude, USU16 4743, UB92, 5038. 51626 S32u, S463, S600. S735. S873. 6010. 614d, 62756 6405, 65326 6658, O7E1. 6903.6 7022, 71406 72576 7372. 7465. 7597.6 7707. 7Blbe 7924, 6 J96 4284S Q-L LIGIHXI WHARZA ENGINEERING COMPANY EXIT ae 2|3| 4 Preconstruction Activities Organization, Larrnd Selection anid Alternative 5tudy Declaration of Intention Feasibility Study-Provrsioral -Firral Environmental Other Permits : FINANCING Design, Contract Documents ¢ Award Construction Mobilization | Docking Facilities and Access foads Diversion Dam Penstock ee Powerhouse Turbines and Generators ct Transmss/or Testing arid Commissioning ALASKA POWER AUTHORITY THAYER CREEK PROJECT IMPLEMENTATION SCHEDULE HAR ZA eNciINEERING COMPANY AUGUST 1979 Appendix T-A GEOLOGY Regional Geology General Formations of Southeast Alaska vary from Lower Ordovician volcanics (in some places deposited in marine environments) and cherts to poorly consolidated recent glacial (fluvioglacial and glacio-marine) clastics. The older (Tertiary and older) beds are often intricately folded and faulted. Folding and faulting apparently occurred in several different episodes in the past, and, judging from current seismic activity and apparent differ- ential uplift of opposite sides of the Chatham Strait, continue in the present. Stratigraphy In general the older (pre-Tertiary) sedimentary rocks are marine as evidenced by black shales, cherts and limestone, (or their metamorphic equivalents e.g. slates and marbles). Volcanism, which is still present, has occurred intermit-— tently since the early Paleozoic. This is evidenced by basalt or andesite volcanic flow rocks, or welded tuffs in unmetamor- phosed areas and by greenstones in metamorphic sequences. Plutonic activity has occurred during at least four geo-periods - the Silurian, Jurassic, Lower Cretaceous and Lower Tertiary. Plutonic rocks vary from granites to gabbros. In places, rock sequences have been subjected to low grade regional metamorphism which has produced schists, green- stones, slates and marbles. Bedding is often difficult to differentiate from foliation in many of these sequences. In addition to the regional metamorphism, aureoles, or zones of contact metamorphic rocks, surround many of the plutonic rocks. Structure Southeast Alaska is a part of the Coast Range of the west coast that extends from California northward to the Alaskan Peninsula. As such, it is a broad belt of interconnected ranges that has been subjected to several episodes of folding and faulting and plutonic intrusions. THA =i. The several episodes of folding, and faulting, and plutonic intrusions have resulted in extremely complex geology. This geology is additionally complicated by a system of strike-slip faults where horizontal movement has been large enough to bring different facies of contemporanous strata into juxtaposition. These faults generally trend northwestward in conformity with the structural grain of the area and often have large vertical movements. Some are apparently active. Seismicity Orogenic Earthquakes. The seismic history of Southeast Alaska, while short, shows a high level of activity. A large amount of this appears to be related to the seismic activity of the circum-Pacific orogenic belt (or "ring of fire"). This belt is characterized by a deep oceanic trench (the Aleutian Trench), a principal tectonic line with epicenters of shallow earthquakes and active or recently extinct volcanos (the Aleutian Islands) with epicenters of earthquakes originating at depths near 100 km. This Pacific orogenic belt is the classical concept of thrust faulting extending to substantial depths. Earthquakes foci increase in depth as distance from the oceanic trench increases. Master faults, primarily strike-slip in character, account for much of the seismic activity of Southeast Alaska. These faults, shown on Exhibit T-A-l, occupying and bounding the Coast Range orogenic belt, can, in places, be identified to pass through the area. Major seismic activity attributed to these faults is described below. The map of epicenters, generally shows a correlation between faulting and seismic activity. (a) The Fairweather-St. Elias-Chugach Fault is the larg- est and most active in coastal Alaska. Activity associated with this fault resulted in the Lituya Bay earthquake of July 10, 1959. This movement was at least 70 feet laterally and 21.5 feet vertically. Other large earthquakes, including the Prince William Sound, Alaska, earthquake of 1964, and the Yakutat Bay earthquake of September 10, 1899, may also have originated on this fault. (b) A second major fault, the Denali-Chatham Strait Fault passes through the Alexander Archipelago along Chatham Strait, joining the Fairweather Fault west of Prince of Wales Island. The northern end of this fault is considered to be active and this activity is believed to have formed scarps along the Alaska Range. There is no reported evidence of movement of T-A-2 the fault; however, the Denali-Chatham Strait Fault is long and it should not be assumed that it is inactive. Some severe earthquakes appear to have originated on the northern part of the fault. Many other faults appear to be related to the Chatham Strait - Fairweather Fault System. Within the area of Southeast Alaska, these faults, in general, are considered to be inactive or dead faults, in that they have not moved during the Holocene. Earthquakes in the area often cannot be related to known surface faults and may be presumed to be indigenous to the area. Design for such earthquakes should be ona zonal basis. It should be noted that seismic activity is largely concentrated between the Chatham Strait and Fairweather Faults and along and to the west of the Fairweather Fault. Sites significantly east of the Chatham Fault should be expected to experience a lower level of activity. Volcanic Earthquakes. Several large earthquakes have been attributed to volcanic eruptions on the Aleutian Islands. These have resulted in tsunamis. Tsunamis or Tidal Waves. One of the effects of earthquakes can be the formation of seismic sea waves or tsunamis. General- ly these are generated by submarine earthquakes; however, earthquakes with epicenters on land can also cause tsunamis. Within the area of Southeast Alaska, tsunamis can generally be expected to be generated in the Aleutian Trench, along the Fairweather Fault, or in the Japan Trench. Several have been reported that can be attributed to movement along the Fair- weather Fault. Potential tsunami generation could also occur in Southeast Alaska by earthquakes on the Chatham Strait Fault, and one reported in 1899 in Lynn Canal may have originated on this fault. Powerplant sites on or very near the coast could be damag- ed by tsunamis. Physiography The overridding factor in the formation of the present terrain of Southeast Alaska has been Wisconsinian glaciation. Glaciers apparently originated from ice caps on the larger islands, and then spread into the lower areas as valley and tidewater glaciers. In some areas, local mountain glaciers resulted in the formation of cirques and hanging valleys. Retreat of glaciers occurred approximately 10,000 years ago, a short period of time from a geological standpoint. TAS Removal of glacial ice loads resulted in substantial rebound of land masses at some places (approximately 700 ft. for Douglas Island as reckoned from present sea level). Because of the short period of time since glaciation, drainage systems are often poorly integrated, streams are immature, flowing through valleys with oversteepened sides and with steep gradients in places, and through shallow isolated lakes and muskegs in other places. The rebound phenomena apparently are not present in all islands. Furthermore, the phenomena have been complicated by rising sea levels following melting of glacial ice and possibly differential movement along major faults, such as the Chatham Strait Fault. The results of these factors with reference to the project area are that: (1) The upper parts of Thayer Creek and Thayer Lake appear to have been formed by valley glaciers. These glaciers in turn flowed into larger tidewater glaciers; (2) Upper parts of drainage basins for creeks are poorly integrated; and (3) Thayer Creek has eroded its course near the coast through a sharp ridge bordering Chatham Strait. This suggests substantial uplift with reference to present sea level of this part of the coast. Debris Avalanches and Landslides A major consideration of some sites and reservoirs in valleys with oversteepened sides could be debris avalanches of soils and of weathered and broken rock and glacier deposits which could fill the reservoir and damage project facilities. The literature of the area reports instances of destructive debris avalanches and other mass wasteage phenomena. Many scars are found on aerial photographs, observed from planes, or found on ground attesting to commonness of these phenomena. Bent tree trunks on some slopes indicate creep movement and potential instability. In general, debris avalanches occur on oversteepened slopes, i.e. slopes exceeding 36°. This is slightly steeper than the commonly accepted 33° angle of repose for talus deposits. Commonly the debris avalanche involves relatively thin cohesionless soils and thin surficial layers of broken and weathered rock. In some cases the layering of broken and weathered rock results from stress relief joints which are generally parallel to the surface and which appear to have been T-A-4 formed as a result of relief of stress following melting of glaciers. Triggering mechanisms can be large increases of soil moisture due to rain or disruption of drainage due to construc- tion activities, logging, or other activities that remove vegetation. Earthquakes also can trigger debris avalanches. Rock falls from cliffs are one of the mass wasteage phenomena. Good engineering practice can eliminate hazards to projects from this source. Other types of landslides of either rock or soil probably occur in Southeast Alaska. These do not appear to be factors in the area of these projects. Thayer Creek Geology Physiography Thayer Lake and much of Thayer Creek is a juvenile drainage basin reflecting a recent glacial history with numerous small lakes, muskegs and a poorly integrated drainage system. However, near the coast, where the proposed dam would be located, Thayer Creek has eroded a deep steep sided canyon. The depth of the canyon, which is from 300 to 400 feet, apparently is determined by uplift of this part of Admiralty Island caused by the rapid rebound of Admiralty Island following melting of Late Pleistocene glaciers and by possible uplift along the Chatham Strait Fault. Rapids are located along the creek near the coast and the valley is narrow and sides are steep, and in places precipitous. Valley sites are covered with thin overburden deposits of talus and trees, which often show signs of hill creep (bent tree trunks, small shallow slumps). These are indicators of over- steepened slopes which are confirmed by the 45° slope of the canyon walls. The many indicators of the instability of overburden on the valley sides suggest that a reservoir near the mouth of Thayer Creek would be rapidly filled with debris and/or that installa- tions in the area could be damaged by debris avalanches. Seismicity Proximity of the site to Chatham Strait and the Chatham Strait Fault would suggest that movement on this fault could T-A-5 severely shake the site. While the fault is generally con- sidered to be inactive, its length and apparent relationship to the Fairweather Fault would make it suspect. Regardless of the activity on the Chatham Strait Fault, southeast Alaska is a seismically active area and structures should be designed to withstand strong shaking. The powerplant site, which would be near the coast could also be susceptible to tsunamis originating on the Chatham Strait Fault. Other Faults have been recognized in the area, one passing near the site (see USGS Bulletin 1181-R). These apparently are inactive. Geological Investigations Geological investigations of the site area consist of regional work done by the USGS and reported in their Bulletin 1181-R, Reconnaissance Geology of Admiralty Island, Alaska, by E.H. Lathram, J.S. Pomeray, H.C. Berg and R.A. Loney (1965). Other literature refered to in a general manner is listed in the Bibliography. Current investigations have consisted of a visit to the project area by Harza personnel in July 1979. Site Geology Rocks found at the site belong to marbles of the Devonian- Gambier Bay Formation. At the dam site and in the powerplant area, the marble of the Gambier Bay Formation is a medium grey, finely crystalline, hard foliated marble with interlayer of calc-schist. Folia layers are often laminae but vary to 6 in. apart. Layers are generally coated with chlorite mica. The results of petro- graphic analyses of rock samples taken from the site are given on Exhibit T-A-2. Foliation generally strikes NW and parallel to the coast and dips 40°NE. The rock mass is intersected by a strong set of vertical joints that are essentially at right angles to foliation. Another set of vertical joints strikes N-S. Both joint sets appear to locally control direction of stream flow. Engineering Geology Dam, Spillway, and Penstock Intake. Stripping from the dam's abutments will require removal of organic matter and soil from both the foundation area and from the slopes to an elevation of possibly 200 feet. The stripping above the dam's foundation area would include removal of unstable material from above the work area. Some trimming and shaping of rock cliffs may also be required. The keyway for the dam need be only nominal because of the stabilizing effect of the downstream constriction of harder rock which forms the upper falls. It is anticipated that a trench l foot deep x 3 feet wide would be adequate. A modest grout curtain to minimize uplift pressure should also be adequate. It is recommended that in the channel area this grout curtain consists of holes 10 feet deep drilled at 5 foot centers and angled N85E. Abutment grouting of holes 10 feet deep on 10 foot centers and drilled normal to the slope is recommended. Powerplant. The powerplant will be founded on bedrock. Protection from tree blow down and debris avalanche should be provided by cutting larger trees in the area and, as necessary, removing soil and talus. Proposed Exploration Dam, Spillway and Penstock Intake. It is recommended that 5 drill holes totaling 250 feet be drilled. All holes should be inclined 45°, two to cross beneath the channel, one directed under the east abutment, and two drilled into the west abutment. Penstock. One inclined, 50 foot deep hole should be drill- ed to the south near the anchor block for the concave penstock bend. Powerstation. One drill hole 30 feet deep should be drilled at the powerstation location. EM PesT ||| 7 rend, Black Bear Lake Gunnuk Creek Q Cathedral falls Creek Gartina Creek Thayer Creek ims Creek LEGEND: «/ Epicenter of earthquake, number of events Tan interred. aan aa dotted where concealed of inferre LOCATIONS OF FAULTS AND EARTHQUAKE EPICENTERS ALASKA POWER AUTHORITY e Al Only earthguake of 3.0 + magnitude or BUA R27 enoneeene oor eterare D+ intensity are shown. Exhibit T-A-2 PETROGRAPHIC INVESTIGATION OF SAMPLES FROM THE ALEXANDER ARCHIPELAGO, S.E. ALASKA. A.F.Koster van Groos Thayer Creek, lower downstream Macroscopic: Calcite-rich calc-schist Microscopic: Calcite, epidote, chlorite rich, substancial amount of quartz-like phase, but with lower refractive index, should be identified with X-ray methods; no chert seen Conclusion: calc-schist with some unusual minerals. Thayer Creek, upper downstream site Macroscopic: green-grey banded schist Microscopic: strongly altered:plagioclase, albite, Fresh K-spar, large amount of chlorite,minor epidote Andalusite-rich bands, some quartz. some calcite Conclusion: relatively normal schist, no chert seem. Conclusions: All the samples from the Alexander Archipelago seem to be rather normal. The only exception is the sample from Thayer Creek, at the lower downstream site. The degree of weathering of all samples is slight. Most fractures are healed with either chert-like deposits, quartz, or calcite. The degree of alteration is often substancial, eSpecially when the original rock is of volcanic origin Appendix T-B HYDROLOGY Climate The climate of the project area is largely maritime with occasional incursions of continental air masses. Therefore, the climate is mild and humid with much precipitation. The primary factor influencing the climate is the Aleutian low pressure area, which is semi-permanent in the fall and winter but tends to migrate in the spring and summer. Temperatures The maritime influences cause temperatures to be mild and uniform. The occasional incursions of continental air cause considerably colder temperatures for short periods. Exhibit T-B-l shows average and extreme temperatures for a climatological station in the project area. Precipitation The normal cyclonic wind pattern of the low pressure area, aided by high mainland mountains to the northeast, results in a high percentage of the winds being from the southeast quadrant. In addition, these southeasterly winds bring rain a far greater percentage of the time than do winds from other quadrants. Therefore, southeastern exposure is an important factor in the precipitation pattern, and hence runoff, of the project area. In latitudes south of the project area, the cyclonic circu- lation results in the prevailing winds being from the southwest. Therefore, moisture from warmer seas is carried in a generally northward direction, passing over cooler water, thereby lowering the air temperature. This, along with cyclonic convergence and local orographic effects, produces copious rainfall with large variations over short distances. Precipitation, however, varies less from year to year, and from season to season, than in most places. The moderate temporal variation in rainfall is highly favor- able to hydroelectric power but the geographical variations make the computation of power potential from ungaged basins somewhat uncertain. This problem is discussed later under "streamflow". T=B=L Storms tend to be general and for extended periods. In- tense precipitation of the thunderstorm type is very rare, and is never nearly as intense as in warmer climates. This leads to very much smaller flood peaks in small basins than are found in warmer humid areas. Flood volumes, however, can be large. Precipitation data are shown for a climatological station in the project area in Exhibit T-B-l. Streamflow Streamflow data are far more extensive in the project area than are precipitation data. Streamflow data integrate the con- ditions for the entire drainage basin about the gage. There- fore, streamflow records generally are far more valuable than precipitation records in estimating the water supply at the various sites. Elevation, orientation, and location affect both the amount and distribution of runoff. These three factors are discussed below: Effect of Elevation Studies were made by the Alaska Power Administration and its predecessor, the U.S. Bureau of Reclamation, of the effect of elevation on runoff in the Alaskan panhandle. (Takatz Creek Project, Alaska-Juneau, September 1967). The curves of Drawing 1113-906-21 of that report, shown here as Exhibit T-B-2, indicate that the average increase in unit runoff for the areas studied is about 0.0045 cfs per square mile for each additional foot of average basin elevation. The project areas covered herein generally have much lower precipitation and runoff per unit of drainage area than the areas studied in the above report. The project drainage basins in general also have higher elevations than the basins above the stream-gaging stations. Therefore, it is considered prudent to use an elevation adjustment two thirds as large as indicated above. Therefore, an increase in unit runoff of 0.003 cfs per square mile for each foot of additional average basin elevation is adopted. An independent check of this elevation adjustment factor was made by comparing the one year of simultaneous record at the upper and lower gages on Mahoney Creek near Ketchikan. The records of these stations confirmed the value of 0.003 cfs per square mile for each foot of elevation. The confirmation is only partial, however, because of the poor quality and short records of the Mahoney gages. Where the basin is small and most of it is within the spill- over area at the upwind basin divide, the average elevation of the upwind divide is substituted for the average basin elevation TB e and a partially subjective factor applied to adjust for the effectiveness of the spillover. Mr. Robert Cross, Administrator of the Alaska Power Administration, who is highly experienced in Alaskan hydrology, pointed out instances where there is a noticeable dropoff in precipitation within two miles of the upwind divide. This is considered in estimating the adjustment factor. Elevation not only affects the mean annual runoff but also the seasonal distribution of the runoff. Drawing 1113-906-20 of the Takatz report shows the seasonal effect for the Baranof Island area. This same effect was used in the project area. The drawing is shown on Exhibit T-B-2. Effect of Orientation Examination of precipitation and runoff records, discussions with meteorologists and hydrologists, and published reports all indicate that exposure to the southeast has a significant effect on precipitation and runoff. The "Climatic Atlas of the Outer Continental Shelf Water and Coastal Regions of Alaska - Volume I, Gulf of Alaska" by the Bureau of Land Management, 1977 indicates that the predominant winds in the project area are from the southeast and that such winds are accompanied by significant rainfall a much greater percentage of the time than are other winds. Therefore, presence or lack of exposure to the southeast was given careful consideration in transposing runoff from gaging stations to project basins. Effect of Location The effect of location was taken into account by selecting gaging stations as index stations in the general vicinity of the project. Streamflow Records Since these are reconnaissance level studies, published data of the U.S. Geological Survey, along with computer analyses by the USGS, are used to define the streamflow at the gaging stations. Some of the streamflow records are very short. Annual variations in runoff, however, are very moderate in the project area. Therefore, average runoff records of five years or longer are used without adjustment. Records were available only for 1977 for several stations. Comparing the 1977 runoff with long BS term runoff for stations having long records, indicates that 1977 was fairly representative of the long term average with some stations having somewhat greater than average runoff in 1977 and other somewhat less. Therefore, records for the single year 1977 are used without adjustment but with caution. All comparisons of runoff are made on the basis of cfs per square mile to eliminate the variable of basin size. Runoff based on these comparisons is subject to inaccuracies in the published data and to uncertainty in accounting for elevation, exposure, and location, as discussed earlier. Runoff Computation Runoff is estimated on the basis of drainage area, basin ele- vation, and exposure comparisons with gaged basins. Basin ele- vations also are computed for gaged basins used in the compari- sons. Drainage areas are determined by planimetering 1:63, 360 scale or 1:250,000 scale topographic maps. Basin elevations are de- termined by laying out grids over the basins and averaging the elevations of each grid over the basins, then averaging the elevations at each grid intersection. Grid scales are selec- ted for each basin such that they average about 40 grid inter- sections. There is a gaging station on Hasselborg Creek about 15 miles to the east of the Thayer Creek site having fairly comparable runoff. The station has 18 years of record (1951 to 1968) and is rated "excellent". This station has an average adjusted runoff of 5.73 cfs per square mile. Using the grid system on a 1:250,000 scale map gives an average basin elevation of 1080 for Hasselborg Creek. The Thayer Creek basin averages about 1270 in elevation. Using 0.003 cfs/sq. mi. increase in runoff per foot of elevation gives 0.003 times (1270- 1080) or 0.57 cfs per square mile increase for the basin or a total of about 6.3 cfs per sq. mi. For the drainage area of 64.3 sq. mi. the average flow is 405 cfs and the mean annual flow volume is 4860 cfs-months. The average annual flow is then distributed over the year in accordance with the seasonal relationships shown on Exhibit T-B-2 to arrive at average monthly flows. Average monthly flows are shown on Table T-B-l. Table T-B-1l AVERAGE MONTHLY INFLOW AT THAYER CREEK SITE Month Inflow, cfs January LSS February E59) March 150 April 282 May aS June 664 July 421 August 366 September St October 659 November 452 December 288 Annual Average 405 Flow-Duration Computations Computer printouts of daily flow were obtained from the U.S. Geological Survey for Hasselborg Creek. The printout includes flows for the station exceeded 95, 90, 75, 70, 50, 25 and 10 percent of the total days in the record, irrespective of season of occurrence of such flows. The flow duration values for this index station then are multiplied by the ratio of average flow at the project site to the average flow for the index station. The resultant flow duration curve for Thayer Creek is shown on Exhibit T-5 of the main report. Probable Maximum Flood The probable maximum precipitation (PMP) falling in 24 hours on an area up to 10 square miles is derived from a provi- sional isohyetal map included with a report on probable maximum precipitation being prepared for later publication by the National Weather Service. Correction factors are given ina provisional curve prepared for that report. From these two curves, PMP quantities are derived for durations divisible by 6 hours from 6 hours to 72 hours. By substracting the PMP for consecutive durations, incre- mental precipitation is derived for each 6 hours for the 3-day a —Bi=5) storm period. These are maximized sequentially (placing the 12 6-hour values in the most critical sequence). The highest increment is placed in the 7th period the the second highest in the 6th period, the third highest in the 8th period, the fourth highest in the 5th period, etc. Basin retention is taken as 0.05 inches per hour. No initial retention is used for the basin because the PMP probably will come in a very rainy season. Unit hydrographs are estimated by the Snyder method. Six hour unit hydrographs are used to simplify manual computations. Flood peaks, flood volumes and Creager's "C" values for the peaks are given in Table T-B-2 and the PMF hydrograph is shown on Exhibit T-B-3. Table T-B-2 PROBABLE MAXIMUM FLOOD SUMMARY Drainage Area, $ - mi. 64.3 Flood Peak, cfs— 1/ 43,000 Flood piel Ea 74,000 Creager's "C"=— 44 17 Thayer Lake inflow, routed outflow is discussed in Chapter T-Il. Other Hydrologic Factors Other hydrologic factors that are briefly noted but not studied in detail were evaporation and sediment. Evaporation Evaporation losses are small and already reflected in the streamflow records of streams having natural storage. In the case of new storage, evaporation will be partially or wholly compensated because presently vegetated land areas will be flooded. Sediment Sediment observations in the panhandle area of Alaska indicate that suspended sediment will not be a significant T-B-6 problem in basins not containing active glaciers. It is probable that bed load will be more nearly normal than will suspended load. Projects having only small pondage may experience a grad- ual diminution of the pondage. For projects having active stor- age it is unlikely that sediment will be a problem. Downstream channel degradation should be allowed for in alluvial channels, but is unlikely to be a serious problem. ADGOON _ JAN FEB MAR APR MAY | JUL AU SEP OCT NOV DEC ANNUAL AVERAGE TEMPERATURE 27.9 28.7 33.6 (39.4 46.2 51.8 O52 | 56.6) 49.3) 22.35 (9618 | 3.3) 41.2 HIGHEST TEMPERATURE 57 50 54 | 64 76 83 84 81 75 65 65 54 84 LOWEST TEMPERATURE -10 -10 -2 15 24 30 36 32 27 10 a “l= -10 AVERAGE PRECIPITATION 4.33 3,34 2.80 2360 2.30 /1.88 |3.13.)|/3576) 6.09 7.22 1/5525 || 4.69) 47.21 AVERAGE SNOWFALL 20.3 19:6 12/4) 209 0.3 0 0 0 0 0.4 6.3 15.8 76.7 Alaska Power Authority H : : Thayer Creek arza Engineering Co., Aug. 1979 Hydrologic Data [-9-1 FEqLUXa Exhibit 7-8-2 TAKATZ CREEK PROJECT RUNOFF — : and PRECIPITATION DISTRIBUTION 8 \, Toxotz L. Outlet 2 Tokotz Cr. 7 Green Ll. Outlet 6.Sowmill Cr, 2000! 3. Boranof R. 4.Deer Ll, 8 Moy & June WEIGHTED MEAN DRAINAGE AREA ELEV.& PREC.GAGE ELEY, FT. x November & April Period July& October : LS Period 5. Baranof (Precip) 9, Sitka (Precip) (eo =~ ao = = == -- ~~ -f---- Q----~------ tre mg eta Ne + + + te a > A RaaiaGn 20 30 40 50 60 70 80 RUNOFF or PRECIPITATION as PERCENT of ANNUAL NOTE: 1-5 On eosisid:, 6-9 on westside of Island. © November- April © Moy-June D Juiy- October APA Drwg Mo, (tt3- 905-20. Probable Maximum Fload _ Thayer Creek (Lower) . Zz ntlew to Thayer Lake 4000 < 8. 1 t yar Lake (fs) | appr ontigeta ty ge. §. 8 8 8 8 4 4 8 8 8 PME | Enffon to Tha oe 8 2.004 } t ~ pnw he meres: ek Hours. Fram Start of. Rainfall. inn SL —_ L cb | Har2za Eng. CO. Aug 79. ALASKA POWER AUTHORITY | THAYER. CREEK PROUECT. UNIT HYDROGRAPH 7 &-F-L LIGSHXZ Appendix T-C ENVIRONMENT Summa ry The potential environmental effects of the project have been identified and mitigating actions are recommended. Permit requirements are analyzed and requirements presented for addi- tional data. The principal environmental review agency for the project will be the Alaska Department of Fish and Game Habitat Protec- tion Service, with possible input from the U.S. Forest Service Land Management Planning office. Based on the information presently available, these agencies do not perceive any critical environmental issues which would preclude project development, provided project lands can be acquired by Kootznoowoo, Inc. (Angoon's native corporation) or an other private party. The project site is located on lands in the Tongass National Forest which are being recommended for inclusion in the Wilderness System. Water projects are not permitted on wilderness lands except by authorization of the President. Additional environmental data will be required, of course, and the project will be subject to federal, state, and local environmental review and regulatory processes. Immediately downstream of the project site there is a waterfall which is impassable to fish, so no fish passage facilities would be required. Magnitude of Potential Impacts Potential impacts on migratory salmonid populations due to slight changes in streamflow, temperature, and other parameters can probably be minimized by proper project design and operation. Proper construction procedures and scheduling could minimize potential adverse stream sedimentation effects by preventing erosion and slumping of steep slopes at the site. Construction blasting would probably have to be scheduled to avoid the salmon spawning season. Precautions will have to be taken during placement of the timber crib loading facility in order to minimize potential impacts on salmon entering the stream. Access road and transmission line construction could dis- turb or eliminate wildlife habitat along right-of-way clear- ings, and would adversely affect visual esthetics in this T-C-1 roadless area. The principal impact of dewatering the falls would be on visual esthetics. Recommendations If the project is shown to be feasible, Kootznoowoo, Inc., or other appropriate private party should initiate steps to acquire project site lands. The Alaska Department of Fish and Game and U.S. Forest Service should be asked to assist in assembling the ecological data required to determine potential project effects in greater detail. These agencies should also be kept advised of refinements in project concepts and design so that their input can be included as planning proceeds. A Declaration of Intention fully describing the project should be filed with the Federal Energy Regulatory Commission as soon as possible to determine whether the agency has jurisdiction over the project. Other agencies with major review and/or regulatory responsibilites should also be contacted. These agencies are listed in the main report. Environmental Reconnaissance Thayer Creek Site Location and Land Ownership The project would be run-of-the-river and would provide practically no storage at a dam located in Section 35, T49S R67E, Copper River Meridian, Alaska. The site is located on U.S. Forest Service (USFS) land in the Tongass National Forest and Admiralty Island National Monument, in Value Comparison Unit (VCU) 161 of Management Area C22 (USFS 1979) VCU 161 has been assigned a Land Use Designation (LUD) of I in the Tongass Land Management Plan (USFS 1979). LUD I lands are being recommended for inclusion in the National Wilderness Preservation System, and water development projects would not be permitted unless specifically authorized by the President of the United States (USFS 1975, 1979)- Section 35 adjoins the mandatory selection core township area of Kootznoowoo, Inc., Angoon's native corporation. Kootznoowoo could select Section 35 or part thereof by 17 Acronyms are listed in Exhibit T-C-l T-C= 2) reducing selections in the optional selection area located to the east of the core township (Calvin 1979). In view of the restraints on development on LUD I and Wilderness lands, Kootznoowoo would almost certainly have to acquire project site lands before project development could proceed. Project Area and Natural Resources Lakes and Steams. Thayer Creek drains Thayer Lake and flows into Chatham Strait. The creek emerges from a steep- walled rocky gorge 200 yards from the high tide mark, and there is a waterfall impassable to anadromous fish™ 0.2 mile upstream from the stream mouth (ADFG-DCF no date). The proposed dam would be located a short distance upstream of the falls. Vegetation. are vegetation in the watershed is typical of spruce-hemlock~™ coastal forest. The area has not been logged. Wildlife Resources. Wildlife in the project area would be expected to be generally representative of Admiralty Island fauna. Larger Admiralty mammals include brown bear and Sitka black-tailed deer (Clark and Lucas 1978). Most of the more than 200 bird species common to south- eastern Alaska would be expected to occur on the island (Clark and LUcas 1978). Fisheries Resources. Thayer Creek is catalogued as an anadromous fish stream (No. 112-17-050) (ADFG 1975) and sup- ports spawning runs of pink and chum salmon and perhaps coho salmon (ADFG-DCF no date, Ingledue 1979). Pink salmon is the principal species utilizing the sty am, and Alaska Department of Fish and Game (ADFG) escapement— counts show peak escape- ment during the last 20 years of 17,000 pinks in 1970 (ADFG-DCF no date). The pink run usually begins in late August (Ingledue 1979). Salmon spawning is restricted to the 0.2 mi reach from the intertidal zone to the foot of the falls (ADFG-DCF no date). 27 Those that spend some part of their life in salt water and return to fresh water to spawn. 3/ Scientific names of flora and fauna mentioned in the text are listed in Exhibit T-C-2. 4/ Number of adult fish returning to spawn. T=-C=3 Thayer Lake in the upper watershed is classified as first quality cutthroat trout waters (Jones 1978), and this species may occur in the stream above the project site. No other information was available on resident stream fish. Endangered and Threatened Species. The only fish or wild- life species listed by the U.S. Fish and Wildlife Service as endangered or threatened in Alaska are four migratory bird species: the Eskimo curlew, the American and Arctic peregrine falcons, and the Aleutian Canada goose (USFWS 1979). These birds would be expected to pass through the general project area only infrequently and the project should have no effect on them. Potential Project Impact and Mitigation Measures Access Roads and Transmission Lines. There are no roads in the project area. Access road construction and transmission right-of-way clearing could disturb or eliminate wildlife habitat and adversely affect visual esthetics. Road construction near the stream could cause sediment runoff, which may be harmful to fish eggs and juveniles in the downstream salmon spawning and rearing areas. Proper construction procedures and scheduling would minimize impacts of erosion, but special care is necessary for any road construction in the steepwalled part of the canyon. Precautions will have to be taken during place- ment of the timber crib loading dock, since such activities could interfere with the passage of salmon into Thayer Creek. Construction of Dam and Generating Facilities. The falls immediately downstream of the damsite is impassable to fish, so no fish passage facilities would be required for the project. Construction activities in the stream could disturb sub- strate materials and cause resuspension and downstream redeposition of fines, which could adversely affect fish eggs and young in the downstream spawning areas. Erosion and slumping of the steep sides of the canyon at the site could also occur, with the same result. Proper construction pro- cedures and scheduling could reduce these impacts. Blasting operations at the site might have to be scheduled to avoid the salmon spawning season because of the proximity of salmon spawning areas. Eggs in the early stages of development are easily killed by even minor shocks (Logan 1979). Noise may also cause wildlife to temporarily abandon the area, but the animals should return once construction is completed. Provisions will have to be made during dam construction to pass adequate stream flow so that downstream aquatic T-C-4 habitat is maintained, especially during the salmon spawning and rearing season. Some clearing of vegetation may be required but would not be extensive. Vegetation above reservoir maximum pool eleva- tion should not be disturbed if possible in order to avoid de- stabilization of the steep slopes. Operation. The reservoir would have less than daily stor- age capacity so that effects on general water quality downstream would be expected to be minor. Downstream water temperatures and dissolved oxygen concentrations might be slightly changed, depending on the level of the reservoir from which water is withdrawn and on water retention time in the impoundment. The natural stream discharge regime would probably be modified only slightly, but project operation might have to be adjusted at times to provide adequate downstream flows for salmon. The falls would be dewatered part of the time, but this would not affect fish populations. The principal impact of dewatering the falls would be on visual esthetics. Regulatory Requirements and Reviews Federal. If the project is located entirely on tribal land, the Federal Energy Regulatory Commission (FERC) may not have jurisdiction. Such a determination would be made by the FERC itself, and may depend on additional factors, such as whether the affected stream is navigable (the FERC has auth- ority to declare a stream to be navigable or that it affects the interests of interstate commerce) (Gotschall 1977). The choice of Rural Electrification Administration (REA) financing could also necessitate an FERC license, since federal funds would be involved. The FERC would make its jurisdictional decision after receiving a "Declaration of Intention" which fully describes the project. If the FERC determines that a license is required, the project would be in the minor project category (less than 1.5 MW installed capacity), and the application for license would have to include the following (FERC 1978): Exhibit K. Definition of project lands and boundaries. Exhibit L. Description of project structures and equip- ment. Copies of necessary federal, State of Alaska, and local permits, approvals, and certifications. T-C€-5 Applicant's Environmental Report, including: 1. Description of project and mode of operation, 2. Description of the environmental setting, ae Description of expected environmental impacts, and enhancement and mitigation measures, 4. Description of project alternatives, including alternative sites and sources of energy, and Ss Description of consultations with federal, State, and local agencies during preparation of the environmental report. The information required for this report should be commensu- rate with a preliminary environmental assessment to determine the need for an Environmental Impact Statement. Whether or not a FERC license is required, the following federal permits must be obtained: 1. U.S. Army Corps of Engineers (USACE) - Section 404 Federal Water Pollution Control Act (FWPCA) permit for discharge of dredge and fill material into U.S. waters; Section 10 Rivers and Harbors Act permit if the stream is determined to be navigable. 2. U.S. Environmental Protection Agency (USEPA) - Section 402 FWPCA National Pollutant Discharge Elimination System (NPDES) permits for point source discharges. Construction phase and powerhouse sump pump discharge NPDES permits will be necessary, and depending on the outcome of a current suit to classify hydroelectric facilities as point source discharges, an NPDES permit for project operation could also be required. Other federal agencies which would probably review a FERC license application and the applications for other federal permits include U.S. Fish and Wildlife Service, National Marine Fisheries Service, USFS, the Heritage Conservation and Recrea- tion Service, the Alaska Power Administration, and the Bureau of Indian Affairs. The REA would also review the FERC license application if REA funding is to be used for the project. During review of the FERC license application and the appli- cations for permits from USACE and USEPA, any of these federal T-C-6 agencies may determine that preparation of an Environmental Impact Statement is required. REA would also be empowered to make such a determination. State of Alaska. Permits and review concerning environ- mental aspects of the project which would be required from State agencies include (ADCED & ADEC 1978): Le Department of Environmental Conservation - Certifi- cate of Reasonable Assurance for Discharge into Navigable Waters (in compliance with Section 401 of the FWPCA); Waste Water Disposal Permit (the Department may adopt the NPDES permit issued by USEPA as the required State permit) Ze Department of Fish and Game, Habitat Protection Service - Anadromous Fish Protection Permit. Required of any hydraulic project located on a catalogued anadromous fish stream, this permit may impose stipulations on construction timing, project design and operation requirements, and other mitigation measures. De Department of Natural Resources, Division of Land and Water Management - Water Use Permit (authorizes dam construction and appropriation of water). 4. Office of the Governor, Division of Policy Development and Planning, Office of Coastal Management - review of development projects in Alaska's coastal zone to insure compliance with coastal management guidelines and standards (AOCM & USOCZM 1979). Coordination. To assist those who must obtain permits from one or more federal, State of Alaska, or local agencies, the applicant may submit a single master application to the Alaska Department of Environmental Conservation (ADEC), who will then circulate the application to the other appropriate State agencies for comment and review (AOCM & USOCZM 1979). The State permits and review listed above are all included in this process which is not mandatory but rather intended to aid the applicant. In addition, the Division of Policy Development and Plan- ning (DPDP) of the Office of the Governor, through the A-95 Clearinghouse System, acts as lead agency in the coordination of the review of environmental reports, environmental impact statements, federal assistance programs, and development projects (AOCM & USOCZM 1979). Although no explicit or T-C-7 procedural criteria are applied to these reviews, Alaska does employ A-95 as a major vehicle for solicitation and coordina- tion of agency responses to proposed energy development activities. Satisfaction of FERC and Other Agency Requirements Consultation and cooperation with federal and State natural resources agencies during project planning is required by the FERC and is also necessary during the process of application for permits from these agencies. If project planning proceeds, the principal environmental review agency would be the ADFG Habitat Protection Service, with possible input from the USFS Land Management Planning office (Brannon 1979, Reed 1979). Based on the information presently available, these agencies do not perceive any critical environmental issues which would preclude development of the project, provided project lands can be acquired by Kootznoowoo, Inc., or other private party (Brannon 1979, Reed 1979). Additional environmental data will be required, of course, and the project will be subject to the federal, State, and local environmental review and regulatory process outlined previously. In order to facilitate future project planning and develop- ment it is recommended: Le That the selection of project site lands be undertaken by Kootznoowoo, Inc., or appropriate private party, if the project is demonstrated to be feasible. 2. That USFS and ADFG be asked to assist in assembling the ecological data required to determine in greater detail the magnitude of potential project effects On anadromous fish runs. The other potential impacts outlined previously should also be discussed with these agencies. 3. That USFS and ADFG be kept advised of refinements in project concepts and design and that their input be solicited and included as planning proceeds. 4, That a Declaration of Intent fully describing the project be filed with the FERC as soon as possible so that the agency may determine whether or not it has jurisdiction for the case of complete tribal ownership of project lands and the case of REA financing. T-C-8 References Alaska Dept. of Commerce and Economic Development and Alaska Dept. of Environmental Conservation (ADCED & ADEC) 1978. Directory of Permits, State of Alaska, March 1978. Juneau. Alaska Dept. of Fish and Game (ADFG), 1975. Catalog of Waters Important for Spawning and Migration of Anadromous Fishes, Region 1. Juneau, 97 p. Alaska Dept. of Fish and Game, Division of Commercial Fisheries (ADFG-DCF). No date. Stream Survey Report-Thayer Creek - 112-17-050. Alaska Office of Coastal Management and U.S. Dept. of Commerce Office of Coastal Zone Management (AOCM & USOCZM), 1979. State of Alaska Coastal Management Program and Final Environmental Impact Statement. Juneau, Alaska, and Washington, D.C. May 30, L9795) |) 578 ip.) +) maps. Brannon, Ed. 1979. Group Leader for Land Management Planning and Regional Environmental Coordinator, U.S. Forest Service, Juneau, Alaska. Personal communication. Calvin, Jim, 1979. Director of Lands and Minerals Management, U.S. Forest Service, Juneau. Personal communication. Clark, Roger N. and Robert C. Lucas, 1978. The Forest Ecosystem of Southeast Alaska: 10. Outdoor Recreation and Scenic Resources. USDA Forest Service Gen. Tech. Report PNW-66. Pacific Northwest Forest and Range Experiment Station, Portland, Oregon. 116 p. Elliott, Steve, 1979. Alaska Dept. of Fish and Game, Division of Sport Fisheries, Project Leader, Juneau. Personal communi- cation. Federal Energy Regulatory Commission (FERC), 1978. Short Form Hydroelectric License. Federal Register, Vol. 43, No. 176 - Monday, September 11, 1978, pp. 40215-40219, Gotschall, Don, 1977. Memorandum: Phone conversation with Federal Power Commission on licensing procedures U.S. Dept. of Energy, Alaska Power Adminstation, Juneau. Ingledue, Don, 1979. Alaska Dept. of Fish and Game, Division of Commercial Fisheries, Juneau. Personal communication. T-C—1'0 Jones, Darwin E., 1978. A Study of Cutthroat-Steelhead in Alaska. Volume 19 Anadromous Fish Studies, Job No. AFS 42-6, July 1, 1977 - June 30, 1978. Alaska Dept. of Fish and Game, Sport Fish Division, Juneau, 119 p. Logan, Richard, 1979. Alaska Dept. of Fish and Game, Office of the Commissioner, Habitat Protection Service, Juneau. Personal communication. Reed, Richard, 1979. Alaska Dept. of Fish and Game, Habitat Protection Service, Regional Supervisor, Juneau. Personal communication. U.S. Fish and Wildlife Service (USFWS), 1979. Fish and Wildlife Service List of Endangered and Threatened Wildlife. 50 CFR 17.11; 43 FR 58031, Dec. 11, 1978; amended by 44FR 29478, May 21, 1979. U.S. Forest Service (USFS), 1979. Tongass Land Management Plan Final Environmental Impact Statement (Two Parts). Alaska Region, Forest Service, U.S. Dept. of Agriculture, Juneau, Alaska, March 1979. U.S. Forest Service (USFS), 1975. Tongass National Forest Guide (1975 Draft). Alaska Region, Forest Service, U.S. Dept. of Agriculture, Juneau, Alaska, 253 p. + app. T=C— i Exhibit f-C=1 ACRONYMS ADEC Alaska Dept. of Environmental Conservation ADFG Alaska Dept. of Fish and Game ADNR Alaska Dept. of Natural Resources DPDP Division of Policy Development and Planning FERC Federal Energy Regulatory Commission FWPCA Federal Water Pollution Control Act LUD Land Use Designation NPDES National Pollutant Discharge Elimination System REA Rural Electrification Administration USACE U.S. Army Corps of Engineers USEPA U.S. Environmental Protection Agency USFS U.S. Forest Service USFWS U.S. Fish and Wildlife Service VCU Value Comparison Unit SCIENTIFIC NAMES Common Name hemlock, mountain hemlock, western spruce, Sitka bear, brown deer, Sitka black-tailed salmon, chum (dog) salmon, coho (silver) salmon, pink (humpback) trout, cutthroat curlew, Eskimo falcon, American peregrine falcon, Arctic peregrine goose, Aleutian Canada Trees Mammals Fish Birds Exhibit T-C-2 Scientific Name Tsuga mertensiana Tsuga heterophylla Picea sitchensis Ursus arctos Odocoileus hemionus sit- kensis Oncorhynchus keta Oncorhynchus kisutch Oncorhynchus gorbuscha Salmo clarki Numenius borealis Falco peregrinus anatum Falco peregrinus tundrius Branta canadensis leuco- pareia Appendix T-D REFERENCES Federal Power Commission and the Forest Service - U.S.D.A. "Water Powers Southeast Alaska," Washington and Juneau, 1947. Robert W. Retherford Associates, Preliminary Appraisal Report, Hydroelectric Potential for Angoon, Craig, Hoonah, Hydaburg, Kake, Kasaan, Klawock, Klukwan, Pelican, Yakutat, Anachorage, 1977. U.S. Department of Agriculture, Rural Electrification Administration, "Alaska 28 THREA - Power Requirements Study", May 1979 draft.