HomeMy WebLinkAboutAPA220ACRES AMERICAN INCORPORATED
1577 C Street
Suite 305
Anchorage, Alaska 99501
Te 1 ephone: ( 907) 279-9631
ALASKA POWER AUTHORITY
SUSITNA HYDROELECTRIC PROJECT
TASK 6 -DEVELOPMENT SELECTION
SUBTASK 6.05
DEVELOPMENT SELECTION REPORT
FINAL REPORT
DECEMBER 1981
ACRES AMERICAN INCORPORATED
1000 Liberty Bank Building
Main at Court
Buffalo, New York 14202
Telephone: (716) 853-7525
ALASKA POWER AUTHORITY
SUSITNA HYDROELECTRIC PROJECT
SUSITNA BASIN DEVELOPMENT SELECTION
VOLUME I -MAIN REPORT
TABLE OF CONTENTS
Page
LIST OF TABLES ......................................... ,................ iii
LIST OF FIGURES.......................................................... vii
1 -INTRODUCTION
1 . 1 -The Study Area. . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
1.2-Project Description ......•.................................... 1-2
1.3-Objectives and Scope of Current Studies .................•..... 1-2
1.4 -Plan Formulation and Selection Process........................ 1-5
1.5-Organization of Report ........................................ 1-7
2 -SUMMARY
2.1 -Scope of Work .......................•....•.................... 2-1
2.2-Previous Studies ..•.............. ~ ............................ 2-1
2.3-Railbelt Load Forecasts ....................................... 2-2
2.4-Railbelt System and Future Power Generating Options ........... 2-4
2.5 -Susitna Basin................................................. 2-5
2.6-Susitna Basin Development Selection ........................... 2-9
2.7-Susitna Hydroelectric Development ..•.......................... 2-11
2.8-Conclusions and Recommendations ..............•................ 2-12
3 -SCOPE OF WORK
3.1 -Development Selection Studies ...•............................. 3-1
3.2-Continued Engineering Studies ................................. 3-3
4 -PREVIOUS STUDIES
4.1 -Early Studies of Hydroelectric Potential ...................... 4-1
4.2-U.S. Bureau of Reclamation-1953 Study ....................... 4-2
4.3 -U.S. Bureau of Reclamation -1961 Study ..... ~................. 4-2
4.4-Alaska Power Administration-1974 ........................•... 4-2
4.5-Kaiser Proposal for Development .............••.•.............. 4-2
4.6-U.S. Army Corps of Engineers-1975 and 1979 Studies .......... 4-3
5 -RAILBELT LOAD FORECASTS
5.1-Introduction .................................................. 5-1
5.2-Electricity Demand Profiles •.................................. 5-2
5.3-ISER Electricity Consumption Forecasts ........ , ............... 5-2
5.4-Past Projections of Railbelt Electricity ...................... 5-6
5.5 -Demand Forecasts.............................................. 5-7
5.6-Potential for Load Management and Energy Conservation ......... 5-8
5.7-Load Forecasts Used for Generation Planning Studies ........... 5-9
i
ALASKA POWER AUTHORITY
SUSITNA HYDROELECTRIC PROJECT
SUSITNA BASIN DEVELOPMENT SELECTION
VOLUME I -MAIN REPORT
TABLE OF CONTENTS (Cont.)
6 -RAILBELT SYSTEM AND FUTURE POWER GENERATING OPTIONS Page
6.1 -Introduction.................................................. 6-1
6.2 -Existing System Characteristics............................... 6-2
6.3-Fairbanks-Anchorage Intertie................................ 6-3
6.4-Hydroelectric Options......................................... 6-4
6. 5 -Therma 1 Options.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-7
6. 6 -Impact of the Fue 1 Use Act. . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . 6-12
6.7-Other Options ...................... : .......... ~............... 6-14
7 -SUSITNA BASIN
7.1 -Introduction.................................................. 7-1
7.2-Climatology and Hydrology..................................... 7-1
7. 3 -Region a 1 Geo 1 ogy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-4
7.4-Seismic Aspects ............ ,.................................... 7-6
7.5-Environmental Aspects......................................... 7-9
8 -SUSITNA BASIN DEVELOPMENT SELECTION
8.1 -Terminology ................. ~.................................. 8-1
8.2-Plan Formulation and Selection Methodology.................... 8-1
8. 3 -Dam Site Se 1 ect ion. . . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . 8-2
8.4 -Site Screening................................................ 8-4
8.5-Engineering Layout and Cost Studies........................... 8-5
8.6-Formulation of Susitna Basin Development Plans................ 8-12
8.7-Evaluation of Basin Development Plans......................... 8-19
8.8 -Comparison of Generation Scenarios With and Without the
Susitna Basin Development Plan................................ 8-29
9 -SUSITNA HYDROELECTRIC DEVELOPMENT
9. 1 -Se 1 ected Plan. . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-1
9.2-Project Description........................................... 9-1
9.3-Construction Schedules........................................ 9-9
9.4-Operational Aspects .. ~........................................ 9-10
9.5-Environmental Review ................. ~........................ 9-11
10 -CONCLUSIONS AND RECOMMENDATIONS
10.1 -Conclusions.................................................. 10-1
10.2 -Recommendations............................................... 10-2
i i
LIST OF TABLES
Number
5.1
5.2
5.3
5.4
5.5
5.6
Title
Historical Annual Growth Rates of
Electric Utility Sales ......................•........ 5-12
Annual Growth Rates in Utility Customers and
Consumption Per Customer ............................. 5-13
Utility Sales by Railbelt Regions .................... 5-14
Railbelt Electricity End-Use Consumption (GWh) ....... 5-15
Base Case Forecast (MES-GM) (GWh) .....•......•....... 5-16
Summary of Railbelt Electricity Projections 5-17
5.7 Summary of Recent Projections of Railbelt
Electric Power Requirements (GWh) .................... 5-18
5.8 Performance of Past Projections Railbelt
Electric Power Requirements .......................... 5-19
5.9 Forecast Total Generation and Peak Loads -
Total Railbelt Region ................................ 5-20
5.10 Railbelt Region Load and Energy Forecasts Used
For Generation Planning Studies ...........•.......... 5-21
6.1 Total Generating Capacity Within the Railbelt
6.2
6.3
6.4
6.5
6.6
7.1
7.2
System .................................•..•.......... 6-16
Generating Units Within the Railbelt-1980 .......... 6-17
Operating and Economic Parameters for Selected
Hydroelectric Plants ................................. 6-19
Results of Economic Analyses of Alternative
Generation Scenarios ................................. 6-20
Summary of Thermal Generating Resource Plant
Parameters .......................................••.. 6-21
Alaskan Fuel Reserves .............................•.. 6-22
Summary of Climatological Data ....................... 7-18
Recorded Air Temperatures at Talkeetna and
Summit in oF ......................................... 7-19
iii
LIST OF TABLES (Cont•d.)
Number
7.3
7.4
7.5
7.6
7.7
Title
Maximum Recorded Ice Thickness on the
Susi tna River ........................................ 7-20
Average Annual and Monthly Flow at Gage in the
Susitna Basin ........................................ 7-21
Flood Peaks at Selected Gaging Stations on the
Susitna River ........................................ 7-22
Suspended Sediment Transport ......................... 7-23
Different Vegetation Types Found in the Susitna
Basin ................................................ 7-24
8.1 Potential Hydroelectric Development .................. 8-32
8.2 Cost Comparisons ..................................... 8-33
8. 3 Dam Crest and Full Supply Levels ..................... 8-34
8.4 Capital Cost Estimate Summaries Susitna Basin Dam
Schemes Cost in $Million 1980 ........................ 8-35
8.5 Results of Screening Model ........................... 8-36
8.6 Information on the Devil Canyon Dam and
Tunnel Schemes ....................................... 8-37
8.7 Devil Canyon Tunnel Schemes Costs, Power Output and
Average Annua 1 Energy ................................ 8-38
8.8 Capital Cost Estimate Summaries Tunnel Schemes
in $Mi 11 ion 1980 ..................................... 8-39
8.9 Susitna Development Plans ............................ 8-40
8.10 Energy Simulation Sensitivity ........................ 8-43
8.11 Susitna Environmental Development Plans .............. 8-44
8.12 Annual Fixed Carrying Charges ........................ 8-47
8.13 Results of Economic Analyses of Susitna Plans -
Medium Load Forecast ................................. 8-48
8.14 Results of Economic Analyses of Susitna Plans -
Low and High Load Forecast ........................... 8-49
iv
LIST OF TABLES (Cont•d.)
Number Title Page
8.15 Results of Economic Sensitivity Analyses for
Generation Scenario Incorporating Susitna Basin
Development Plan 1.3-Medium Forecast ............... 8-50
8.16 Economic Backup Data for Evaluation of Plans
8.17 Economic Evaluation of Devil Canyon Dam and
Tunnel Schemes and Watana/Devil Canyon and
8-51
High Devil Canyon/Vee Plans .....................•.... 8-52
8.18 Environmental Evaluation of Devil Canyon Dam and
Tunne 1 Scheme ........................................ 8-53
8.19 Social Evaluation of Susitna Basin Development
Schemes/Plans ........................................ 8-54
8.20 Energy Contribution Evaluation of the Devil
Canyon Dam and Tunne 1 Schemes . . . . . . . . . . . . . . . . . . . . . . . . 8-55
8.21 Overall Evaluation of Tunnel Schemes and Devil
Canyon Dam Scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-56
8.22 Environmental Evaluation of Watana/Devil Canyon and
High Devil Canyon/Vee Development Plans .............. 8-57
8.23 Energy Contribution Evaluation of the Watana/Devil
Canyon and High Devi 1 Canyon/Vee Plans ............... 8-59
8.24 Overall Evaluation of the High Devil Canyon/Vee
and Watana/Devi 1 Canyon Dam Plans .................... 8-60
8.25 Results of Economic Analyses for Generation
Scenario Incorporating Thermal Development Plan -
Medium Forecast ....................................... 8-61
8.26 Economic Sensitivity of Comparison of Generation
Plan with Watana/Devil Canyon and the All Thermal
Plan ................................................. 8-62
8.27 Social Comparison of System Generating Plan with
Watana/Devil Canyon and the All Thermal Plan ......... 8-63
8.28 Generic Comparison of Environmental Impacts of a
Susitna Basin Hydro Development Versus Coal Fired
Thermal Generation in the Beluga Coal Fields ......... 8-64
v
LIST OF TABLES (Cont•d.)
Number Title
8.29 Overall Evaluations of All Thermal Generation Plans
with the Generation Plan Incorporating Watana/Devil
Canyon Dams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-6 5
9.1 Outflows from Watana/Devil Canyon Development
Stage 1 Watana 400 MW ................................ 9-15
9.2 Outflows from Watana/Devil Canyon Development
Stage 2 Watana 800 MW ......................•......... 9-16
9.3 Outflows from Watana/Devil Canyon Development
Stage 3 Devil Canyon 400 MW .......................... 9-17
10.1 Energy and Capacity Forecasts for 2010 ............... 10-4
vi
LIST OF FIGURES
Number
1.1
1.2
1.3
4.1
5.1
5.2
5.3
6.1
6.2
6.3
6.4
6.5
6.6
7.1
7.2
7.3
7.4
7.5
7.6
Title Paqe -·-
Location Map ......................................... 1-10
Plan Formulation and Selection Methodology ........... 1-11
Planning Approach .................................... 1-12
Damsites Proposed by Others .......................... 4-4
Historical Total Railbelt Utility Sales to
Final Customers ...................................... 5-22
Forecast Alternative Total Railbelt Utility Sales 5-23
Energy Forecasts Used For Generation Planning
Studies .............................................. 5-24
Location Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-23
Formulation of Plans Incorporating Non-Susitna
Hydro Generation ..................................... 6-24
Selected Alternative Hydroelectric Sites ............. 6-25
Generation Scenario Incorporating Thermal and
Alternative Hydropower Developments -Medium
Load Forecast ........................................ 6-26
Formulation of Plans Incorporating All-Thermal
Generation ........................................... 6-27
All Thermal Generation Scenario-Medium Load
Forecast ............................................. 6-28
Data Collection Stations ..............•.............. 7-25
Average Annual Flow Distribution Within the Susitna
River Basin .......................................... 7-26
Monthly Average Flows in the Susitna River at
Gold Creek ........................................... 7-27
Regional Geology ..................................... 7-28
Relative Densities of Moose-November, 1980 ......... 7-29
Winter Distribution of Moose-March, 1980 ........... 7-30
vii
LIST OF FIGURES (Cont•d.)
Number
7.7
8.1
8.2
8.3
8.4
8.5
8.6
8.7
8.8
8.9
Title Page
Location and Territorial Boundaries of Wolf
Packs -1980 ......................................... 7-31
Susitna Basin Plan Formulation and Selection
Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-66
Profile Through Alternative Sites .................... 8-67
Mutually Exclusive Development Alternatives · .......... 8-68
Damsite Cost vs Reservoir Storage Curves
Damsite Cost vs Reservoir Storage Curves
Damsite Cost vs Reservoir Storage Curves
Schematic Representation of Conceptual Tunnel
8-69
8-70
8-71
Schemes .............................................. 8-72
Capital Cost vs Energy Plots for Environmental
Susitna Basin Plans .................................. 8-73
Generation Scenario with Sustina E1.3 -Medium
Load Forecast ........................................ 8-74
8.10 Generation Scenario with Susitna E2.3 -Medium
Load Forecast ........................................ 8-75
8.11 Generation Scenario with Susitna E3.1 -Medium
Load Forecast ........................................ 8-76
8.12 Generation Scenario with Susitna E1.5 -Load
Load Forecast ........................................ 8-77
8.13 Generation Scenario with Susitna E1.3 -High
Load Forecast ........................................ 8-78
9.1 Watana Fill Dam Preliminary Construction Schedule .... 9-18
9.2 Devil Canyon Thin Arch Dam Preliminary Construction
Sc hedu 1 e . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-19
9.3 Stage 1 -Watana Reservoir (400 MW) Operation of the
Watana/Devil Canyon Development Plan E1.3 ............ 9-20
9.4 Stage 3 -Watana Reservoir (800 MW) Operation of the
Watana/Devil Canyon Development Plan E1.3 ............ 9-21
viii
LIST OF FIGURES (Cont'd.)
Number
9.5
9.6
9.7
9.8
Title
Stage 3-Devil Canyon Reservoir (400 MW) Operation
of the Watana/Devil Canyon Development Plan El.3
Discharge -Stage Frequency Curve Susitna River
Page
--"'--
9-22
at Gold Creek . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-23
Discharge -Stage Frequency Curve Susitna River
at Susitna Station ................................... 9-24
Discharge-Stage Frequency Curve Susitna River
at Sunshine .......................................... 9-25
ix
LIST OF PLATES
Number
1
2
3
4
5
6
7
8
9
10
11
12
13
Title Page
Devil Canyon Hydro Development Fill Dam .............. 8-79
Watana Hydro Development Fi 11 Dam .................... 8-80
Watana Staged Fi 11 Dam ............................... 8-81
High Devil Canyon Hydro Development .................. 8-82
Susitna III Hydro Development ......... · ............... 8-83
Vee Hydro Development ................................ 8-84
Dena 1 i & Mac 1 aren Hydro Deve 1 opment s ................. 8-85
Preferred Tunnel Scheme 3 Plan Views 8-86
Preferred Tunnel Scheme 3 Sections ................... 8-87
Devil Canyon Scheme 1 Plan and Section ............... 9-26
Devi 1 Canyon Scheme 1 Sections ....................... 9-27
Watana Scheme 2 9-28
Watana Scheme 2 Sections ............................ . 9-29
X
1 INTRODUCTION
This report has been prepared by Acres American Incorporated {Acres) on behalf
of the Alaska Power Authority (APA). The report es~entially represents a
milestone in the Plan of Study {POS) for the Susitna Hydroelectric Project ·
currently being undertaken by Acres under the terms of an Agreement with APA
dated December 19, 1979. The Susitna POS was first issued in February 1980 and
subsequently revised in September 1980. It describes in detail the many and
complex studies to be undertaken from January 1980 through June 1982 to assess
the feasibility and the environmental impact of the proposed Susitna Project~
The POS dlso addresses the requirements for filing a F~RC license application
should p·oject feasibility and environmental acceptability be established.
Studies through March 1981 have mainly been concerned v1ith evaluation of the
need for electric power in the Alaska Railbelt Region and consideration of the
alternatives for meeting these power needs both with and without a Susitna Basin
hydroelectric development. This Development Selection Report presents the
results of this initial step in the POS process, and provides recommendations
and justification for continuation of study of a specific basin development.
The remainder of Section 1 of this report deals with a descriptiort of the study
al"ea and the proposed Susitna development and a summary of the objectives and
scope of the current studies.
1.1 -The Study Area
The main stream of the Susitna River originates about 90 miles south of Fair-
banks where melting glaciers contribute much of its summer flow (see Figure
1.1). Meandering for the first 50 miles in a southerly direction across a broad
alluvial fan and plateau, it turns westward and begins a 75 mile plunge between
essentially continuous canyon wail? before it changes course to the southwest
and flows for another 125 miles in a broad lowland. For more than 30 years, the
vast hydroelectric potential of this river has been recogn~zed and studied.
Strategically located in the heart of the South Central Railbelt, the Susitna
could be harnessed to produce about twice as much electrical energy per year as
is now being consumed in the Railbelt.
The Susitna River syst.em, with a drainage area of more than 19,000 square miles,
is the sixth largest in Alaska. Major tributaries include the Yentna, Chulitna:)
Talkeetna, and Tyone rivers. A substantial portion of the total annual stream-
flm'l occurs during spring and summer and is generated by glacial melt and
rainfall runoff. The water during this period is turbid. Winter flows consist
almost entit'ely of ground water supply and are generally free of sediment.
Freezeup starts in October in the upper reaches of the basin, and by late
November ice covers have formed on all but the most rapidly flowing stretches of
the river. Breakup tenerally occurs around early May.
The Susitna River and its tri: Jtarie~ are important components of Alaska's
highly prolific fishery resource. Salmon, Dolly Varden trout, grayling, and
whitefish are found within the Basin. Waterfowl habitat in the glacial outwash
plain supports trumpeter swan and migratory fowl. Bear, moose, and caribou
thrive there. In short, wildlife resources are plentifuL. Extensive studies
1-1
/
are necessary both to determine their total value, the impacts which any
development may have upon them, and the nature. of mitigative measures which
might be taken to eliminate or offset negative environmental consequences of
hydroelectric development.
1.2 -Project Description
·The Susitna Basin has been under study since the mid-forties by agencies such as
the Water Resources and Power Services (WRPS, formerly the USBR), the Alaska
Power Admi ni strati on, and the US Army Corps of Engineers ( COE), as we·ll as H .J.
Kaiser and Company. The more recent and most comprehensive of these studies
were carried out by the COE. The optimum method of developing the basin's
potential was determined by the COE to comprise two major hydroelectric
developments. The first of these would require a dam at Watana and the second,
a dam at De vi 1 Canyon. This deve 1 opment vJas found to be economi ca 11 y vi ab 1 e and
would provide the Railbelt area with a long-term supply of relatively cheap and
reliable energy.
Studies completed by Acres to date have ·confirmed that the preferred development
should consist of two large hydroelectric dams at Watana and Devil Canyon (see
Figure 1.1). The Watana dam would be constructed first. It would involve a
fill dam roughly 880 feet maximum height, and because of the large reservoir
volume created would pro~ide adequate storage for seasonal regulation of the
flow. Initially, 400 MW of generating capacity would be installed at this site.
This would later be expanded to around 800 MW to allow for additional peaking
capacity. The Devil Canyon dam would be the next stage of the development. It
would involve a 675 feet maximum height double curvature concrete arch dam and
incorporate a 400 MW powerhouse. The total average annual energy yield from
this development amounts to 6200 GWh.
The power from the total development would be conveyed to the Railbelt system by
as many as four 345 kV transmission lines running from the project sites to the
proposed Anchorage-Fairbanks intertie in the vicinity of Gold Creek. The
capacity of the currently envisaged intertie would ultimately be increased
to a total transmission capability of two 345 kV lines from Anchorage to
Fairbanks.
Access to the project site is still under study. Alternative routes being con-
sidered include a road access from the east via the Denali Highway, and rail and
road access from the west via the Parks Highway, and the railroad passing
through Gold Creek. It is envisaged that substantial air support would be re-
quired during the construction of the project and an airstrip would be
constructed near the Watana site.
The current schedule ca 11 s for the fi r_st 400 MW at Watana to ·be on-line by 1993.
The additional 400 MW at Watana would 'be commissioned as required and probably
be brought on-line in 1996. The Devil Canyon development would be brought
on-line in the year 2000.
1.3 -Objectives and Scope of Current Studies
The prima!·y objectives of the studies are:
-To establish technical, economic, and financial feasibility of the Susitna
project to meet future power needs of the Railbelt region;
1-2
-To evaluate the environmental consequences of designing and constructing the
Susitna project;
File a completed license application with the Federal Regulatory Commission in
June 1982.
0 The overall scope of work involves a broad range of comprehensive field and
office studies over a 30 month period from January 1980 to June 1982. These
have been divided into specific tasks and are discussed briefly below. The
major portion of the work is being conducted b: Acres with the support of
several subcontractors. o
(a) Task 1 -Power Studies
These studies involve the development of a range of power and energy pro-
jections for the Railbelt area. The energy forecast work has been under-
taken by the Institute for Social and Economic Research (ISER) under
contract to APA. Woodward Clyde Consultants (WCC), under subcontract to
Acres, produced the associated load duration curves and power forecasts ..
(b) Task 2 -Surveys and Site Facilities
This task includes the construction and maintenance of a 40 man field camp
located at the Watana sito and the provision of aircraft and helicopter
support to the field teams. The camp construction and maintenance is being
undertaken by Cook Inlet Region, Inc. (CIRI), and Holmes and Narver, Inc.
(H&N) under subcontract to Acreso Local aircraft companies are providing
fixed wing and helicopter support alsu under subcontract to Acres. Also
included in this task is an extensive range of survey and mapping work
being undertaken by R&M Consultants, Inc. for Acres and ancillary studies
dealing with site access, land status, and reservoir clearing studies.
(c) Task 3 -Hydrology
This task incorporates an extensive field data collection program being
conducted by R&M and associated office studies required for the project
which are being conducted jointly by H&M and Acres.
(d) Task 4 -Seismic Studies
This work incorporates a wide range of field and office studies aimed at
developing an understanding of the seismic setting and potential earthquake
mechanisms of the region and determining the seismic design criteria for
the structures to be built. Most of this WOrk is being conducted by wee
under subcontract to Acres.
(e) Task 5 -Geotechnical Exploration
This task incorporates all the geotechnical exploration field work con-
ducted at the Watana and Devil Canyon dam sites. Much of the field work is
being carried out by R&M under subcontract to Acres.
1-3
(f) Jask 6 -Design Development
This task incorporates the planning and engineering studies for selecting
the most appropriate Susitna Basin development plan and for producing the
conceptual engineering designs for the selected development. This work can
be divided into two stages:
(i) Stage 1 -Development Selection
This phase of the work encompasses the river basin planning and Rail-
belt system generation planning work aimed at determining the mo·st
appropriate basin development plan.
(ii) Stage 2 -Feasibility Design
This phase includes the more detailed engineering studies aimed at
optimizing the selected project and producing the ~onceptual designs
for inclusion in the FERC license.
(g) Task 7 -Environmental Studies
These studies encompass a broad range of field and office studies aimed at
determining potential environmental impacts due to the project and de-
veloping appropriate mitigating measuresQ Much of this work is being con-
ducted under subcontract for Acres by Terrestrial Environmental Specialists
(TES). The large game and fisheries studies· are being conducted by The
Alaska Department of Fish and Game (ADF&G) under a reimbursable service
agreement with APA.
(h) Task 8 -Transmission
This task includes the studies necessary to develop conceptual designs for
the transmission system required to convey Susitna power into the Railbelt
system. This work is being conducted by Acres with some support from R .. W.
Retherford and Associates (RWRA), a division of International Engineering
Company { IECO).
(i} Task 9 -Construction Cost Estimate and Schedules
This \-Jork involves the production of detailed construction type cost esti-
mates and construction schedules of the project and is being conducted by
Acres with some assistance from F. Moolin and Associates (FMA).
· (j) Task 10 -Licensing
This task covers the work required to produce the FERC license documents
and is being carried out by Acres.
(k) Task 11 -Marketin9 and Financing
This task includes support studies dealing with the risk and financial as-
pects associated with the project. These studies are requried to identify
and se.cure the necessary funding for the project and are being carried out
by Acres with support from specialist consultants.
1-4
(1) Task 12 -Public Participation Program
APA is conducting an extensive public participation program to keep tjle
public informed on the progress and findings of the study and to obtain
feedback from them on issues they believe are critical to the successful
implementation of the project. Acres and the subcontractors support APA in
these activities on an as required basis.
(m) Task 13 -Administration
This task deals with the Acres administration of the entire study effort.
1.4 -Plan Formulation and Selection Process
A key element in the studies being undertaken is the process which is being
applied for formulation and comparison of development plans. Much emphasis is
being placed on consideration of every important perspective which may influence
the selection of a particular course of action from a number of possible alter-
natives. A description of the generic plan formulation and selection metho-
dology is presented in Appendix A. An essential component of this planning
process is a generalized multi-objective development sele.ction methodology for
guiding the planning decisions. A second important factor is the formulation of
a consistent and rational approach to the economic analyses undertaken by the
studies.
(a) Planning Methodology
A generalized plan formulation and selection process has been developed to
guide the various planning studies being conducted. Of numerous planning
decisions to be made in these studies!t perhaps the most important are the
selection of the preferred Susitna Basin development plan {Task 6), and
appropriate access and transmission line routes (Tasks 2 and 8)e
The basic approach involves the identification of feasible candidates and
courses of action, followed by the development and application of an
appropriate screening process. In the screening process, less favorable
candidates are eliminated on the basis of economic, environmental, social
and other prescribed criteria. Plans are then formulated which incorporate
the shortlisted candidates indjvidually or in appropriate combinations.
Finally, a more detailed evaluation of the plans is carried out, again
using prescribed criteria and aimed at selecting the best development plan.
Figure 1.2 illustrates this general process.
In the final evaluation, no attempt is made to quantify a11 the attributes
used and to combine these into an overall numerical.,evaluation. Instead,
the plans are compared utilizing both quantitative and qualitive attri-
butes, and where necessary, judgemental tradeoffs between the two types are
made and highlighted. This allows reviewers of the planning process to
quickly focus on the key tradeoffs that effect the outcome of the deci-
sions. To facilitate this procedure, a paired comparison technique is used
so that at any one step in the planning proc~ss, only two plans are being
evaluated.
1-5
The studies aimed at ·selecting the best Susitna Basin development plan
involve consideration of a large number of alternative courses of action.
The selection process has been used in three parallel applications in an
attempt to simplify the procedure. Two Railbelt generating scenarios, one
involving only thermal generating units and a second involving a mix of
thermal and other potential (non-Susitna) hydro developments were evaluated
separately, as well as a Susitna/thermal scenario. Information on these
alternative generating scenarios is necessary to make a preliminary
assessment of the feasibility of the .. with Susitna 11 generating scenario by
means of a comparison of the three different scenarios.
Figure 1.3 graphically illustrates the overall planning process. Steps 1
to 5 of the formulation and selection methodology are applied to developing
a plan incorporating all-thermal generation and a plan .incorporating
non-Susitna hydro generation.. These studies are outlined in Section 6 of
this report. The same five steps are also applied to the development of
the best "with Susitna" generating scenario as outlined in Section 8. The
final comparison or evaluation of the three scenarios is carried out using
a compress.ed format of the methodology as a guideline to yield the required
preliminary feasibility assessment.. This aspect of the study is covered at
the end of Section 8.
(b) Economic Analyses
As the proposed Susitna development is a public or State project~ all
·planning studies described are being carried out using economic parameters
as a basis of evaluation.. This ensures that the resulting investment
decisions maximize benefits to the State as a whole rather than any
individual group or groups of residents.
The economic analyses incorporate the following principles:
( i )
( . . ) 1 l •
Intra-state transfer payments such as taxes and subsidies are
excluded;
Opportunity values are used to establish the costs for coal~ oil and
natural gas resources used for power generation in the alternatives
considered. These opportunity costs are based on what the open market
is prepared to pay for these resources. They therefore ref1 ect the
true value of these resources to the State. These analyses ignore the
existence of current term-contractual commitments which may exist~ and
which fix resource costs at values different from the opportunity
costs;
(iii) The analyses are conducted using "real 11 or inflation adjusted
parameters. This means that the in~erest or discount rate used equals
the assessed market rate minus the general rate of inflation.
Similarly, the fuel and construction cost escalation rates are
adjusted to reflect the rate over or under the general inflation
rate;
1-6
(iv) The major impact caused by the use of these inflation adjusted para-
meters is to improve the relative economics of capital intensive pro-
jects (such as hydro generation) versus the high fuel consumption pro-
jects (such as thermal generation). It also leads to the selection of
larger economic optimum sizes of the capital intensive projects4
These shifts towards the capital intensive projects are consistent
with maximizing total benefits to the State.
1.5 -Organiz~tion of Report
The objective of this report is to describe the results of Susitna Basin devel-
opment selection studies, i.e. Task 6, Stage 1. It also· briefly outlines the
results of some of the early Task 6, Stage 2 eng.,neering studies aimed at refin-
ing the project's general arrangements.
In order to improve readibility of the report~ much of the detailed technical
material as well as the review of the statu? of technical support studies is in-
cluded in a separate volumt.~ of appendices. The report is organized as follows:
Volume 1 -Main Report
Section 1: Introduction
Section 2: Summary
This section contains a complete summary of Sections 4 through 10 of the main
report.
Section 3: Scope of Work
This section outlines the scope of work associated with the results presented in
this report.
Section 4: Previous Studies
This section briefly summarizes previous Susitna Basin studies by others.
Section 5: Railbelt Load Forecasts
In this section, the results of the energy and load forecast studies undertaken
by ISER and wee are summarized. It concludes with a discussion of the range of
load forecasts used in the Susitna Basin planning studies.
Section 6: Railbelt System and Future Power Generating Options
This section describes currently feasible alternatives considered in this study
for generating electrical energy to·meet future Railbelt needs. It incorporates
data on the performance and costs of the facilities.
Section 7: Susitna Basin
This section provides a description of the physical attributes of the Susitna
Basin including climatologic, hydrologic, geologic, seismic, and environmental
aspects. ·
1-7
Section 8: Susitna Basin Development Selection
The Susitna Basin planning studies and the Railbelt system generation planning
work carried out are discussed in this section. It includes a destription of
the Susitna Basin development selection process and preliminary assessment of
the economic and environmental feasibility of the selected Watana/Devil Canyon
hydropower development.
Section 9: Susitna Hydroelectric Development
This section describes, in more detail, the selected Watana/Devil Canyon project
and includes a discussion of the results of the preliminary operational studies
and a surrmary environmental review of the project.. The project general arrangE:~
ments described result from initial Task 6, Stage 2 engineering studies and
therefore present a more up-to-date picture than the arrangements described in
Section 8.
Section 10: Conclusions and Recommendations
In this section recommendations are made for the Sus i tna Basin development p 1 an
considered by Acres to merit further study. It also deals with tentative con-
clusions with respect to the project's technical, environmental, and economic
feasibility.
Volume 2 -Appendices
A: Plan Formulation and Selection Process
A description of the generic approach to site scenarios, plan formulation and
p 1 an evaluation is presented.
B: Thermal Generating Sources
This appendix outines the detailed backup to tne thermal generating unit per-
formance and cost information presented in Section 6 of the main report.
C: Alternative Hydro Generating Sources
The studies undertaken to produce the shortlist of a'lternativ·e hydro develop ...
ments discussed in Section 6, i.e. those outside the Susitna Basin, are des-
cribed in this appendix.
D:· Engineering Layout uesign Assumptions
This appendix describes the design assumptions that were made in order to
develop the engineering layouts for potential power development projects at the
Devil Canyon, High Devil Canyon, Wat.ana, Susitna III, Vee, Maclaren, and Denali
sites ..
E: Susitna Basin Screening Model
Here a description is presented of the computer model used to screen out uneco-
nomic basin development plans, as discussed in Section 8.
1-8
"
F: ~~le and Multi-Reservoir Hydropower Simulation Studies
The computer model used to simulate the monthly energy yield from the various
Susitna development plans is described in this appendix. Details are presented
on the average monthly firm and average yields for the development plans discus-
sed in Section 8 of the main report.
G: Systemwide Economic Evaluation (OGP5)
This appendix contains the detailed backup information to the computer model
runs used in the economic evaluation of the various generating scenarios consid-
ered in the planning studies.
H: Engineering Studies
The backup studies to the project general arrangements described in Section 9 of
the main report are presented in this appendix ..
I: Environmental Studies
This appendix contains the detailed backup data on environmental aspects gather-
ed by Acres during the course of investigations and by the various subcontrac-
tors.
1-9
LOCATION MAP
LEGEND_
\f PROPOSED
DAM SITES
'
.
. .
LOCATION rv1AP
.. , 0 !-....
"
FIGUHE 1.1.
DEFINE
OBJECTIVES
INPUT FROM AVAILABLE SOURCES -PREVIOUS AND CURRENT STUDIES
FEEDBACK
FEEDBACK
PLAN FORMULATION AND SELECTION METHODOLOGY
LEGEND
---'\ STEP NUMBER IN
4 STANDARD PROCESS
(APPENDIX A )
FIGURE 1.21MIRI
DEVELOPMENT OF AN ALL
THERMAL GE~ERATING PLAN
DEVELOPMENT OF AN OTHER
HYDRO GENERATING PLAN
DEVELOPMENT OF A SUSITNA
BAS IN GENERATING PLAN
ALL
THERMAL
PLAN
OTHER
HYDRO
PLAN
SUSITNA
PLAN
DEVELOPMENT OF THE BEST
GENERATING SCENARIO
LEGEND
RECOMMENDED
GENERATING
SCENARIO
J APPLICATION OF FtAN
FORMULATION ANO '------~ SELECTION METHOOOLOGY
0 END PRODUCTS
PLANNING APPROACH
1.5 [i] FIGURE
..
2 -SUMMARY
2.1 -Scope of Work
The Scope of Work discussed in the Development Selection Report includes the
development selection studies and prelim1nary engineering studies aimed at
refining the general arrangements of the selected Watana and Devil Canyon dam
projects.
The develoJlllent selection studies constitute Stage 1 of the Task 6 design
studies as described in the Acres POS, and include the following:
(a) Review of Previous Studies and Reports (Subtask 6 .. 01)
{b) Investigate Tunnel Alternatives (Subtask 6.02)
(c) Evaluate Alternative Susitna Developments (Subtask 6.03}
(d) Watana and Devil Canyon Staged Development (Subtask 6.06)
(e) Thermal Generating Resources (Subtask 6.32}
{f) Hydroelectric Generating Sources {Subtask 6.33)
(g) Environmental Analysis (Subtask 6.34)
(h) Load Management and Conservation {Subtask 6.35}
(i) Generation Planning (Subtask 6.36}
(j) Developnent Selection Report (Subtask 6.05)
As the development selection studies were finalized work continued on engineer-
; ng design studies aimed at refining the general arrangements at the Devil Can-
yon and Watana sites. These studies involved the production of alternative
general arrangements incorporating earth/rockfill and concrete arch dams at both
Watana and Dev .1 Canyon. These arrangements w~re co sted and eva 1 uated to
determine which is the most appropriate. Design work is being carried out on
the proposed thin arch dam at Devi 1 Canyon to ensure that such a structure can
safely withstand the anticipated seismic loading. Extensive use was made of
computer stress analyses in the design studies.
2.2 -Previous Studies
Shortly after World War II had ended, the USBR conducted an initial investiga-
tion of hydroel~ctric potential in Alaska, reporting its results in 1948. Res-
ponding to a recommendation in 1949 by the nineteenth Alaska territoria~ legis-
lature that Alaska be included in the Bureau of Reclanation program, the Secre-
tary of Interior provided funds to update the 1948 work. The resulting report,
issued in 1952, recognized the vast hydroelectric potential within the terri-
tory. PArticular emphasis was placed on the strategic location of the Susitna
River between Anchorage a.nd Fairbanks as \!~·ell as its proximity to the conn~ct.i ng
Railbelt (see Figure 1.1).
A series of studies was commissioned over the years to identify dam sites and
conduct geotechnical investigations. By l96lll the Department of the Interior
proposed authorization of the two dam power system involving the Devil Canyon
and the Denali sites. The definitive 1961 report was subsequently updated by
the Alaska Power Administration (at that time an agency of the Bureau of
Reclanation) in 1974, at which time the desirability of proceeding with
hydroelectric development was reaffirmed.
2-1
The COE was also active in hydropower investigations in Alaska during the 1950's
and 1960's, but focused its attention on a more anbitious development at Rampart
on the Yukon River. This project was capable of generating five times as much
electric energy as Sus itna annually. The sheer size and the techno 1 og ic al ch a 1-
lenges associated ~~th Rampart captured the imagination of supporters and
effectively diverted attention from the Susitna Basin for more than a decade.
The Rampart report was finally shelved in the early 1970's because of strong
envirormental concerns and uncertainty of marketing prospects for so much
energy, particularly in light of abundant natural gas which had been discovered
and developed in Cook Inlet.
The energy crisis occasioned by the OPEC oil boycott in 1973 provided some
further impetus for seeking developnent of renewable resources. Federal funding
was made available to complete the Alaska Power Adrn1nistrati.on's update report
on Susitna in 1974 and to launch a prefeasibility investigation by the COE. The
State of Alaska itself commissioned a reassessment of the Susitna Project by the
Henry t1. Kaiser Company in 1974. ' ·
Altho~Agh the gestation period for a possible Susitna Project has been long,
Feder a·~~ Stf1t,2, and private organizations have been virtually unanimous over the
y,-ears iri <'~Ci)I1Inending that the project proceed.
2.3 -Railbelt Load Forecasts
The feasibility of a major hydroelectric project depends in part upon the extent
to Yklich the available capacity and energy are consistent with the needs of the
market to be served by the time the-project comes on line. Attempting to fore-
cast future energy demand is a difficult process at best. It is therefore par-
ticularly important that this exer·cise be accomplished in an objective manner.
For this reason APA and the State of Alaska jointly awarded a separate contract
to ISER to prepare appropriate projections for the Alaska Rai 1 be 1 t reg ion.
(a) Electricity Demand Profiles
Between 1940 and 1978, electricity sales in the Railbelt grew at an avet'age
annual rate of 15 .. 2 percent. This growth wa.s roughly twice that for the
nation as a whole. National and Alaskan annual growth rates for different
periods between 1940 and 1978, and the historical growth of Railbelt
utility sales from 1965 consistently exceeded the national average. How-
ever, the gap has been narrowing due to the gradual maturing of the Alaskan
economy. Gro\~h in the Railbelt has exceeded the national average for two
reasons; the population growth in the Rail belt has been higher than the
national rate, and the proportion of Alaskan households served by electric
utilities was lower than the U.S. average so that some growth in the nt.mber
of customers occurred independently of population growth~
(b) ISER Electricity Consumption Forecasts
The ISER electricity demand forecasting model conceptualized in computer
logic the linkage between economic growth secnarios and electricity
consumption. The output from the model is in the form of projected values
of electricity consunption for each of the three geographical areas of the
2-2
Railbelt (Greater Anchorage, Greater Fairbanks and Glennallen ... Valdez) and
is classified by final use (i.e., heating, washing, cooling, etc.) and
consuming sector {commercial, residential, etc). The model produces output
on a five-year time basis from 1985 to 2010, inclusive.
The ISER model consists of several submodel s 1 inked by key variables and
driven by policy and technical assumptions and state and national trends.
These submodel s are grouped into four economic mode1 s which forecast future
levels of economic activity and four electricity consumption models which
forecast the associated electricity requirements by consuming sectors. For
two of the consuming sectors it was not possible to set up computer models;
therefore simplifying assumptions were made.
The overall approach to derivation of the peak demand forecasts for the
Railbelt Region was to examine the available historical data with regard to
the generation of electrical energy and to apply the observed generation
patterns to existing sales forecasts. Information routinely supplied by
the Railbelt utilities to the Federal Energy Regulatory Commission was
uti 1 i zed to determine these load·-patterns.
The analysis of load patterns emphasized the identification of average
patt~rns over the 10-year period from 1970 to 1979 and did not consider
trends or changes in the patterns with time. Generally, the use of average
values was preferred as it reduced the impact of yearly variations due to
variable weather conditions and outages. In any event, it was not possible
to detect any consistent patterns in the available data.
The average hourly distribution of generation for the first weeks of April,
August and December was used to determine the typical average load pattern
for the various utilities. As a. result of the relatively limited data
base, the calculated load duration curve \-Jould be expected to show less
variation than one computed from a more complete data base, resulting in an
overestimation of the load factor. In addition, hourly data also tend to
average out actual peak demands occurring within a time interval of ·less
than one hour. This could also lead to overestimation of the load factor ..
It is, however, considered that the accuracy achieved is adequate for these
studies, particularly in light of the relatively much greater uncertainties
associated with the lo~d forecasts.
(c) Load Forecasts Used for Generation Planning Studies
Three ISER energy forecasts were considered in generation planning studies.
These include the base case (MES-GM) or medium forecast, a low and a high
forecast. The low forecast is that corresponding to the low economic growth
as proposed by ISER with an adjustment for low _government expenditure
(LES-GL). The high forecast corresponds to the ISER high economic growth
scenario with an adjustment for high government expenditure (HES-GH).
Electricity forecasts derived in this study represent total utility genera'-
tion and include projections for self-supplied industrial and military
generation sectors. Included in these forecasts are transmission and dis-
tribution losses in the range of between 9 and 13 percent, depending upon
the generation scenario assuned. These forecasts, ranging from 2. 71 to
4. 76 percent average annual growth, were adjusted for use in generation
planning studies.
2-3
"
The low forecast case assumed above incorporates an annual growth rate of
2. 71 percent. This rate would be reduced with enforcement of energy con-
servation measures more intensive than those presently in use in the State.
M annual growth rate of 2.1 percent was judged to be a reasonable lower
limit for electrical demand for purposes of this study. This represents a
23 percent reduction in growth rate v.nich is similar to the reduction
developed in an independent study authorized by the State.
The implementation of load management measures would result in an addi-
tional reduction in peak load demand. The residential sector demand is the
most sensitive to a shift of load fran the peak period to the off-peak
period. Over the 1980-2010 period, an annual peak load growth rate of 2.73
percent was used in the low forecast case. lrJith load managanent measures
such as rate reform and load controls, this growth rate could be reduced to
an estimated 2.1 percent. The annual load factor for year 2010 would be
increased from 62.2 percent in the low forecast to 64.4 percent in the
1 owest case ..
2.4 -Railbelt System and Future Power Generation Option~
If constructed, the Susitna Basin developnent plan would provide a major portion
. of the Rai lbel t Region energy needs well beyond the year 2000.. It is clearly
important to detennine the most economic basin developnent plan which clearly
defines details such as dam heights, installed generating capacities, reservoir
operating rules, dan and powerhouse staging concepts, and construction sche-
dules. To accomplish this, it is first necessary to evaluate in economic terms
the plan in the context of the entire Rail belt generating system. This requires
that economic analyses be undertaken of expansion al ternativcs .for the total
Railbelt system containing several different types of generating sources. These
sources include both thermal and hydropower generating facilities capable of
satisfying a specified load forecast. Economic analyses of scenarios containing
alternative Susitna Basin develo!lilent plans being .investigated would then revea.l
W'lich is the most economic basin developr1ent plan. This process and the compar ...
ison of other factors such as environmental impacts and social preferences
essentially falls within the purview of "generation planning 11
•
These systemwide generation planning stud·ies require a comprehensive process of
assanbling the necessary information. This information includes an assessment
of the existing system character·istics, the planned Anchorage-Fairbanks inter-
tie, and deta i 1 s of various generating options including hydroelectric and
thermal. The. implications of the Fuel Use Act (FUA), and consideration of other
options such ·as tidal and geothermal energy generation are also important fac-
tors. Performance and cost information required for the generation planning
studies have been developed for the hydroelectric and thermal generation options
but not for the tidal and geothermal options. Preliminary indications are that
these options are as yet not competitive with the more conventional options
considered.
The tYAJ major load centers of the Railbelt Region are the Anchorage-Cook Inlet
area and the Fairbanks-Tanana Valley area. At present, these tWJ areas operate ,
independently. The existing transmission system between Anchorage and Willow
consists of a network of 115 kV and 138 kV lines with interconnection to Palmer.
2-4
Fairbanks i~ primarily served by a 138 kV line from the 28 MW coal-fired plant
at Healy. Communities between Willow and Healy are served by local
distribution.
There are currently nine electric uti-lities (including the Alaska Power
Administration) providing power and energy to the Railbelt system. l~ith the
exception of two hydroelectric plants, the total Railbelt installed c;apacity of
944 MW as of 1980 consists of fifty-one thermal generation units fired by oil,
gas or coal.
Engineering studies are currently being undertaken for construction of an inter-
tie bet\\een the Anchorage and Fairbanks systems.' As presently envisaged, this
connection will involve a 138 kV transmission line between Willow and Healy and
would provide capability for transferring 50 MW of capacity at any time. It is
scheduled for completion in 1984. Current intertie studies indicate that it is
economic to construct this intertie such that it can be upgraded to the 375 kV
Susitna transmission capability when Watana comes on 1 ine.
It was concluded that a fully interconnected system should be assumed faY' all
the generation planning studies outlined in this report, and that the intertie
facilities would be corrmon to a11 generation scenarios considered. In the pre-
liminary comparisons of alternative generation scenarios, the cost of such
intertie facilities was also assl.l11ed to be common. However, in final compari-
sons of a lesser ntJnber of preferred alternative scenarios, appropriate consid-
eration was given to relative intertie costs. The cost of transmitting energy
from a particular generating source to the interconnected system i.s included in
all cases.
Selection of non-Susitna plans which incorporate hydroelectric developments was
accomplished by the application of a five-step methodology (Figure 1.2). Step 1
of this process essentially established the overall objective of the exercise as
the selection of an optimum Railbelt generation plan which incorporated the pro-
posed non-Susitna hydroelectric deve1opnents, for comparison with other plans.
Under Step 2 of the selection process, all feasible candidate sites were identi-
fied for inclusion in the subsequent screening exercise. A total of 91 poten-
tial sites were obtained fran inventories of potential sites published in the
COE National Hydropower Study and the APA report 11 Hydroelectric Alternatives for
the Alaska Rail~~-lt". From these 91 sites, 10 were selected for further study
on the basis of economic and environmental superiority after a four-iteration
screening process.
2.5-Susitna Basin
Information presented herein on the climatological, physical and environmental
·characteristics of the Susi.tna River Basin has been obtained both from previous
studies and the field programs and office studies initiated during 1980 under
Tasks 3, 4, 5 and 7.
{a) C 1 i mato 1 ogy and Hydro 1 ogy
The climate of the Susitna Basin upstream from Talkeetna is generally
characterized by cold, dry winters and warm, moderately moist st.mmers. The
upper basin is dominated by continental climatic conditions while the lower
2-5
basin falls within a zone of transition between maritime· and continental
climatic influences.
The Susitna River usually starts to freeze by late October·. River ice
conditions such as thickness and strength vary according to the river
channel shape and slope, and more important1y, with river discharge.
Periodic measur'ements of ice thickness at several locations in the .river
have been carried out during the winters of 1961 through 1972. Ice breakup
in the river commences by late April or early May and ice jams occasionally
occur at river constrictions, resulting in rises in water level of up to 20
feet. ·
Seasonal variation of flows is extreme and ranges from very low values in
winter {October to Apri 1) to high summer values {May to September). For
the Susitna River at Gold Creek the average winter and summer flows are
2100 and 20,250 cfs respectively, i ·.e. a 1 to 10 ratio. On the average,
approximately 88 percent of the streamflow recorded at Gold Creek station r
occurs during the summer months. At higher elevations in the basin the
distribution of flows is concentrated even more in the summer months. For
the Maclaren River near Paxson (El 4520 feet) the average winter and stmner
1=1ows are 144 and 2100 cfs respectively, i.e. a 1 to 15 ratio.
The most common causes of flood peaks in the Susitna Basin are sno\\tTie'lt or
a combination of snownelt and rainfall over a large area. Annual maximun
peak discharges generally occur between t4ay and October with the majority,
approximately 60 percent, occurring in June. Some of the annual maximum
flood peaks have also occurred in August or 1 ater and are the result of
heavy rains O'ier large areas augmented by significant snownelt from higher
elevations and glacial runoff.
(b) Regional Geology
The upper Susitna Basin 1 ies within what is geologically called the
Talkeetna fvbuntains area. This area is geologically complex and has a
history·of at least three periods of major tectonic deformation. The
oldest rocks {250 to 300 m.y.b.p.*) exposed in the region are volcanic
flows and 1 imestones which are overlain by sandstones and shales dated
approximately 150 to 200 m.y.b.p. A tectonic event approximately 135 to
180 m.y.b.p. resulted in the intrusion of large diorite and granite
plutons, which caused intense thermal metamorphism. This was followed by
marine deposition of silts and clays. The argillites and phyllites which
predominate at Devil Canyon were· formed from the silts and clays during
fau'lting and folding of the Talkeetna t"'ountains area in the Late Cretaceous
period {65 to.100 m.y.b.p.). As a result of this faulting and uplift, the
eastern portion of the area \vas elevated, and the oldest volcanics and
sediments were thrust over the yqunger metamorphics and sediments. The
major area of deft 'Tiation during this period of activity was southeast of
Devil Canyon and l,,_l uded the Watana area.. The Talkeetna Thrust Fault, a
well-known tectonic feature~ trends northwest through this region. This
fault was one of the major mechanisms of this overthrusting frcm southeast
to northwest. The Devil Canyon area was probably deformed and subjected
to tectonic stress during the same period, but~ no major deformations are
evident at the site.
*m .y .b. p. : mi 11 ion years before present
2-6
The diorite pluton that forms the bedrock of the Watana site was intruded
into sediments and volcanics about 65 m.y.b.p. The andesite and basalt
flows near the site may have been formed immediately after this plutonic
intrusion, or after a period of erosion and minor deposition.
During the Tertiary period (20 to 40 m.ycb.p.) the area surrounding the
sites was again uplifted by as much as 3,000 feet. Since then widespread
erosion has removed much of the older sedimentary and volcanic rocks.
During the last several million years at least tVtQ alpine glaciations have
carved the Talkeetna Mountains into the ridges, peaks, and broad glacial
plateaus seen today. Postglacial uplift has induced downcutting of str·eams
and rivers, resulting in the 500 to 700 feet deep V-shaped canyons that are
evident today, particularly at the Vee and Devil Canyon dan sites. Tilis
erosion is believed to be still occurring and virtual1y all streams and
rivers in the region are considered to be actively downcutting. This con-
tinuing erosion has removed much of the glacial debri·s at higher elevations
but very little alluvial deposition has occurred. The resulting landscape·
consists of barren bedrock mountains, glacial till-covered plains, and ex-
posed bedrock cliffs in canyons and along streams. The arctic climate has
retarded devel opnent of topsoi 1 .
. , .... .furthe~· geologic mapping of the project area and geotechnical investigation
of the proposed dam sites was initiated under the current study in 1980~
and will continue through early 1982.
The Talkeetna fvbuntains region of south-cent\--al Alaska lies within the
Talkeetna Terrain. This term is the designation given to the immediate
region of south-central Alaska that includes the upper Susitna River basin.
The reg ion is bounded on the north by the Dena 1 i Fault, and on the west by
the Alaska Peninsula features that make up the Central Alaska Range. South
of the Talkeetna Mountains, the Talkeetna Terrain is separated from the
Chugach Mountains by the Castle Mountain Fault. The proposed Susitna
Hydroelectric Project dam sites are located in the western half of the
Talkeetna Terrain. The eastern half of the region includes the relatively
inactive, ancient zone of sediments under the Copper River Basin and is
bounded on the east by the Totschunda section of the Denali Fault and the
volcanic Wrangell tvbuntains.
(c) Seismic Aspects
Regional earthquake activity in the p\'·oject area is closely related to the·
plate tectonics of Alaska. The Pacific Plate is underthrusting the North
Jlmerican Plate in this region. The major earthquakes of Alaska, including
the Good Friday earthquake of 1964, have primarily occurred along the
boundary between these plates.
The historical seismicity in the vicinity of the dam sites is associated
with crustal earthquakes within the North Pmerican Plate and the shallow
and deep earthquakes generated within the Benioff Zone, which underlies the
project area. Historical data revea.l that the major source of ear~hquakes
in the site region is in the de,ep portion of the Benioff Zone, with depths
ranging between 24 to 36 miles below the surface. Several moderate size
earthquakes have been reported at these depths. The crustal seismicity
within the Talkeetna Terrain is very low based on historical records. Most
of the recorded ear·thquakes in tile area al~e reported to be r~ 1 ated to the
Dena1 i-Toschunda Fault, the Castle Mountaqn fault .or the Ben1off Zone.
2-7
(d) Environmental Aspects
Numerous studies of the environmental characteristics of the Susitna River
Basin have been undertaken in the pasto The current studies were initiated
in early 1980 and are plo.nned to continue indefinitely. These studies
constitute the most comprehensive and detailed examination of the Susitna
Basin ever undertaken, and possibly of any comparable resource.
The SUsitna basin is inhabited by resident and anadromous fish. The
anadromous group includes five species of Pacific salmon: sockeye (red);
coho {silver); chinook (king); pink (humpback); and chun (dog) salmon.
Dolly Varden are also present in the lower Susitna Basin with both resident
and anadromous populations. Anadromous smelt are known to run up the
Susitna River as far as the Deshka River about 40 miles ·from Cook Inlet~
The project area is known to support species of caribou, moose, bear,
wolves, wolverine and Da11 sheep. '
Furbearers in the Upper Susitna Basin include red fox, coyote, lynx, mink~
pine marten, river otter, short-t a i 1 ed weasel, 1 east weasel, muskrat and
beaver. Direct innundation, construction activities and access can be
expected to generally have minimal impact on th·ese species.
One hundred and fifteen species of birds were recorded in the study area
during the 1980 field season, the most abundant being Scaup and Commor. Red-
poll. Ten active raptor/raven nests have been recorded and of these,) two
Bald Eagle nests and at least four. Golden Eagle nests \-.x>uld be flooded by
the proposed reservoirs, as wouid about three currently inactive raptor/
raven nest sites. Preliminary observations indicate a low population of
waterbirds on the lakes in the re~~on; however, Trllrlpeter· Swans nested on a
n IJllber of 1 akes bet wee~ the Oshe:t na and Tyone Rivers.
Flooding would destroy a 1 arge percentage of the riparian cliff habitat and
forest habitats upriver of Devil Canyon dam. Raptors and ravens using the
cliffs would be expected to find alternate nesting sites in the surrounding
mountains, but the forest inhabitants are relatively common breeders in
forests in adjacent regions. Lesser amounts of lowland.meadows and of
fluviatile shorelines and alluvia, each important to a few species, will
also be lost. None of the waterbod ies that appear to be important to
waterfowl will be flooded, nor \'li11 the important prey species of the up-
1 and tundra areas be affected. Impacts of other types of habitat al tera-
tion will depend on the type of alteration. Potential impacts can be
lessened through avoidance of sensitive areas.
Thirteen small mammal species were found during 1980, and the presence of
three others was suspected. During the fall survey, red-backed voles and
masked shrews ·were the most abundant species trapped; and these, plus the
dusky shrew, appeared to be habitat generalists, occupyin~ a wide range of
vegetation types.. Meadow voles and pygmy shrews were least abundant and
the most restricted in their habitat use, the former occupying only meadows
and the latter forests.
The Susitna River drains parts of the Alaska Range on the north and parts
of the Talkeetna Mountains on the south. Many areas along the east-west
portion of the river, between the confluences of Portage Creek and the
2-8
Oshet~a River, are steep and covered \'/ith conifer, deciduous and mixed
conifer, and deciduous forests. Flat benches occur at the tops of these
banks and usually contain low shrub or woodland conifer corrmunit ies. Low
mountains rise from these benches and contain sedge-grass tundra and mat
and cushion tundra.
The 1980 archaeological reconnaissance in the Susitna Hydroelectric Project
area located and documented 40 prehistoric sites and one historic site. It
is expected that continuous reconnaissance surveys in 1981 will locate
additional ~ites. Sites are also docunented adjacent to the study area
near Stephan Lake, Fog Lakes, Lakes Susitna, Tyone and Louise, and along
the Tyone River. Detenninations of significance of sites will be based on
the intensive testing data collected during the summer of 1981 and national
register criteria which determine eligibility for ·the national register of
historic places ..
Conmercial fisheries constitute the oldest cash-based industry of major
importance within the region. The industry has changed substantially
during the past 20 years and continues to be modified as a result of both
biologic and economic stimuli. The salmon industry has always been a major
component of the industry in terms of volume and value. Since 1955, the
king crab, shrimp, and Tanner crab fisheries have undergone major
developnent, and halibut landings have increased substantially in recent
years. The total wholesale .value of commercial fish and shell-fish for the
domestic fishery of Alaska in 1979 was just over $1.2 billion including a
catch of 459 million pounds of salmon with a wholesale value of just over
$700 million.
Existing land use in the Susitna Project area is characterized by broad ex-
panses of open wilderness areas. Those areas where deve 1 opment has oc-
curr·ed often included small clusters of several cabins or othe.r residences.
There are also many single cabin settlements throughout the basin.
There are approximately 109 structures within 18 miles of the Susitna River
bet ween Gold Creek and the Tyone River. . These inc 1 ude four lodges
involving some 21 structures. A significant concentration of residence
cabins or other structures are found near the Otter Lake area, Portage
Creek, High Lake, Gold Creek, Chunila Creek, Stephan Lake, Fog Lake,
Tsusena Lake, Watana Lake, Clarence Lake, and Big Lake.
2.6 -Susitna Basin Development Selection
A comprehensive series of engineering and planning studies were carried out as a
basis for formulation of Susitna Basin development plans and selection of the
preferred plan. The selection process used is consistent with the generic plan
formulation and selection methodology discussed in Section 1. The recommended
plan, the Watana/Devil Canyon dam project, is compared to alternative methods of
generating Railbelt energy needs including thermal and other potential hydro-
electric developments outside the Susitna Basin on the basis of technical,
economic, environmental and social aspects.
As outlined in the description of the generic plan formulation and selection
methodology (Section 1.4) five basic steps are required .. These essentially
consist of defining the objectives, selecting candidates, screening, formulation
of development plans and finally, a detailed evaluation of the plans.
2-9
The objectives of these studies are essentially twofold; the first is to deter-
mine the optimt.m Susitna Basin develop11ent plan and the second to undertake a
preliminary assessment of the feasibility of the selected plan by comparison
with alternative methods of generatin£ energy.
Throughout this planning process, engineering layout studies were conducted to
refine the cost estimates for power or water storage developnent at several dam
sites within the basin~ As they became available, these data were fed into the
screening and plan formulation and evaluation studies.
The results of the site screening exercise indicate that the Susitna Basin
developnent plan should ·incorporate a combination of several major dams and
powerhouses 1 ocated at one or more of the fo 11 owing sites:
-Dev i 1 Canyon
-High Devil Canyon
-Watana
-Susitna III
-Vee
In addition, the following two sites are to be considered as candidates for
supplanentary upstream flow regulation:
-Maclaren
-Denali
To establish the likely optimum combination of dams, a computer screening model
was used to direct 1 y identify the types of p 1 ans that are most economic ..
Results of these runs indicate that the Devil Canyon/Watana or the High Devil
Canyon/Vee combinations are the most economic. In addition to these t\\0 basic
developnent plans, a tunnel scheme was also introduced. This alternative pro-
vides potential environmental advantages. by replacing the Devil Canyon dam by a
long power tunnel. A further alternative developnent plan involving the two
most economic dam sites, High Devil Canyon and Watana, was also considered.
The main criterion used in the initial selection of Susitna Basin development
plans, is that of economics. Environmental considerations are incorporated into
the assessment of the plans finally selected. The results of the final screen-
; ng process indicate that the Watana/Dev il Canyon and the High Devil Canyon/Vee
plans warrant further, more detailed study. In addition, it was decided to
study further the tunnel scheme and the Watana/High Devil Canyon plan.
Four basin p 1 ans are considered. Plan 1 dea 1 s with the Watana/Dev il Canyon
sites, Plan 2 with the High Devil Canyon/Vee sites, Plan 3 with the Watana
tunnel concept, and Plan 4 with the Watana/High Devil Canyon sites. ID assess-
ir.g these plans, a reach-by-reach comparison was made for the section of the
Susitna River between Portage Creek and the Tyone River. The Watana/Devil
Canyon schane \\Ould create more potential environmental impacts in the Watana
Creek area. However, it was judged that this was more than compensated for by
avoiding the even greater potential environmental impacts in the upper reaches
of the river, which would result from a High Devil Canyon/Vee development.
2-10
From a fisheries' perspective, both schemes would have a similar effect on the
downstrean anadromous fisheries although the High Devil Canyon/Vee scheme would
produce a slightly greater· impact on the resident fisheries in the Upper Susitna
Basin.
Except for the increased ·loss of river valley, bird, and black bear habitat, the
Watana/Devil Canyon development plan was judged to be more environmentally ac-
ceptable than the High Devil Canyon/Vee plan. Although the Watana/Devi1 Canyon
plan is considered to be the more environmentally compatible Upper Susitna
develoflllent plan, the actual degree of acceptabii ity is a question being
addressed as part of ongoing studies.
The two plans in were also evaluated and compared in. terms of energy contribu-
tion criteria. The Watana/Devil Canyon is assessed to be superior due to its
higher energy potential and the fact that it develops a higher proportion of the
h~sin's potential. In terms of social criteria, as in the case of the dam
versus tunnel comparison, the Watana/Devil Canyon plan is judged to have a
slight advantage over the High Dev i1 Canyon/Vee plan because of the higher
potential for displacing nonrenewable resources.
The overall evaluation indicates that the Watana/Devil Canyon plans are gener-
ally superior for ,u.ll the evaluation criteria considered. Thus, the Watana/
Devil Canyon plan is judged to be the best Susitna Basin development plan.
2. 7 -Susitna Hydroelectric Development
The studies discussed in this report conclude that, on the basis of the analyses
to date, the future developnent of Railbelt electric. power generation sources
should include a Susitna Hydroelectric Project. However, further work is
required to fully establish the technical and economic feasibility of the
wJSitna project and to refine its design.
The selected basin development plan involves the construction of the Watana dam
ta a crest elevation currently estimated as 2225 feet, with a 400 MW powerhouse
scheduled to commence operation by 1993. This date is the earliest that a
project of this magnitude can be brought on-1 ine. A delay in this date would
mean that additional thermal units would have to be brought on 1 ine to meet the
pl"ojected demand, resulting in an increase in the cost of power to the consumer.
This first stage would be followed by expansion of the powerhouse capacity to
800 MW by 1996 and possibly the construction of are-regulation dam downstream
to allow daily peaking operations. More detailed environmental studies are
required to firm up the requirement for this re-regulation dam; it may be
possible to incorporate it in the Devil Canyon dam diversion facilit·ies~ The
final stage involves the construction of the Devil Canyon dam to a crest
elevation of 1465 feet with an installed c ...... acity of 400 MW by the year 2000.
Should the load growth occur at a lower rate than the current medium forecast,
then consideration should be given to postponing the capacity expansion proposed
at Watana, and the construction of the Devil Canyon dam to the year 2002, or
possibly even 2005. These latter t\~ dates correspond respectively to the low
forecast and the extreme low forecast incorporating an increased level of load
2-11
management and conserv~tion. For actual load growth rates higher than the
medit.Jll load forecasts, construction of the Devil Canyon dan could be advanced to
1998.
Although it has been demonstrated that this developnent plan is extremely es;o-
nomic for a wide range of possible future energy growth rates, the actual sche-
duling for the various stages should be continuously reassessed on perhaps a
five year basis .. It should also be stressed that the dan heights and installed
capacities quoted above are preliminary and subject to modification as the more
detailed project optimization studies are conducted in 1981. The dan type
selected for the Devil Canyon dam site has been revised from the rockfill
alternative assuned in the initial Basin developnent studies, to a thin
doublecurvature concrete arch darn. More detailed engineering studies carried
out subsequent to the planning studies described have indicated this dan type to
be more appropriate to the site conditions and slightly more cost effective.
At this stage of the study, a preliminary assessment of the construction sche-
dules for the Watana and Devil Canyon dams has been made, mainly to provide a
reasonable estimate of on-line dates for the generation planning studies. trbr·e
detailed construction schedules will be developed during the 1981 studies.
In developing these preliminary schedules~ roughly 70 major construction activi-
ties were identified and the applicable quantities such as excavation, borrO\i
and concrete volumes ~are determined. Construction durations were then estima-
ted using historical records as backup and the expertise of senior scheduler-
planners, estimators and design staff. A critical path logic diagran was devel-
oped from those activities and the project duration was determined. The
critical or new critical activity durations were further reviewed and refined as
needed. These construction logic diagrams are coded so that they may be
incorporated into a computerized system for the more detailed studies to be
conducted during 1981.
2.8 -Conclusions and Recommendations
{a) Conclusions
A standard n!ethodology has been adopted to guide the Susitna Basin develop-
ment selection process described in this report. It incorporates a series
of screening steps and concludes with plan formulation and evaluation pro-
cedures. Both the screening and plan evaluation procedures incorporate
criteria relating to technical feasibility, environmental and socioeconomic
aspects, and economic viability.
The economic analyses are required to assist the State in allocating funds
optimally and are there.fore conducted using a real (i.e., inflation ad-
justed) interest rate of 3 percent and a corresponding general inflation
rate of zero percent. Fuel costs are assumed to escalate at specified
amounts above the general inflation rate. Analyses based on the foregoing
assumptions have allowed certain conclusions to be made fm" future Railbelt
generation planning purposes.
Previous studies over the past 30 years have thoroughly investigated the
potential of the basin, and the most recent studies conducted by the COE
2-12
have concluded that the Watana-Dev il Canyon developnent plan is the
preferred option. However, review of these studies has indicated that a
certain amount of revision is appropriate. These revisiohs are necessary
both to develop a more uniform level of detail for a11 the alternative
sites considered, and to reassess the earlier planning decisions in the
1 ight of current load ·projections 7 which are generally lower than those
used in the earlier studies.
The current (1980) Railbelt System annual energy requirement is estimated
to be 2790 6\\h and the pea.k demand 515 MW. Near future demands can be
satisfied by the existing generating system, the cornnitted expansion at
Bradley Lake (hydroelectric) and the combined cycle (gas-fired) plant at
Anchorage. These will meet the demand until 1993 provided an Anchorage--
Fairbanks inte.rtie of adequate capac1ty is constructed.
A range of technically feasible options capable of meeting future energy
and .capacity demands have been identified and include the fo11o\':ing:
-Thermal Units
. Coal-fired steam generation: 100, 250, and 500 MW
• Combfned cycle generation: 250 MW
, Gas turbine generation: 75 MW
. Diesel generation: 10 MW
-Hydroelectric Options
Alternative developnent plans for the Susitna Basi_n capable of pro-
viding up to 1200 to 1400 MW capacity and an average energy yield of
approx irnate 1 y 6000 G\'1h .
. Ten additional potential hydroelectric developnents located outside
the Susitna Basin and ranging from 8 to 480 I~W in capacity and 33 to
1925 Gwh annual energy yield.
Indications are that the utilities will be subject to the prohibitions of
the Fuel Use Act and that the use of natural gas in new facilities will be
restricted to peak load application only.
The Susitna Basin developnent selection studies indicated that the 1200 ft1W
Watana-Devil Canyon dam scheme is the optimllll basin deve1opnent plan from
an economic~ envirormental, and social point of view. It involves an 880
feet high fill dam at Watana with an ultimate installed capacity of
800 MW, and a 675 feet high concrete arch da11 at Devil Canyon with a 400
NW powerhouse. This project will develop approximately 91 percent of the
total basin potential.
Should only one dam site be developed in the basin, then the High Devil
Canyon dam, which develops 53 percent of the basin potential, provides the
most economical energy. This project, however, is ncit compatible with the
Watana-Devil Canyon developnent plan as the site \\OUld be inundated by the
Devil Canyon developnent.
2-13
Comparison of the Rai1belt system generation scenario incorporating the
Watana-Oevil Canyon Susitna development and the all-thermal option reveals
that the scenario 11 With Susitna" is economically superior and reduces the
total systan present worth cost by $2280 mill ion. An overall evaluation of
these two scenarios based on economic, environmental, and social criteria
indicates that the "with Susitna" scenario is the preferred option.
The "with Susitna" scenario remains the most economic for a wide range loao
forecast and parameters such as interest rate, fuel costs and fuel escala-
tion rates. For real interest rates above 8 percent or fue1 escalation
rates below zero, the all thermal generating scenario becomes more econo~
ic. However, it is not likely that such high interest rates or low fuel
escalation rates would prevail during the foreseeable future.
Economic comparisons of the generating scenarios "with Susitna 11 and the
scenario incorporating alternative hydro opt ions indicate that the present
worth cost of the 11 With Susitna11 scenario is $1190 mill ion less.
Prelimary engineering studies indicate that the preferred dam type at
Watana is a rockfill alternative, while a double curvature thin arch
concrete dan is the most appropriate type for the Uevil Canyon site.
(b) Recommendations
The recommendations outlined in this section pertain to the continuing
studies under Task 6 -Design and Development. It is asslJTied that the
necessary hydrologic, seismic, geotechnical, environmental, and tranmission
system studies will also continue to provide the necessary support data for
completion of the Feasibility Report.
Project planning and engineering studies should continue on the selected
Susitna Basin Watana-Devi1 Canyon development plan. These studies should
encompass the fo 11 owing:
-.Additional optimization studies to define in more detail the Watana-Qevil
Canyon development plan. These studies should be aimed at refining:
. Dam heights.
Installed capacities. As part of this task consideration should also
be given to locating the tailrace of the Devil Canyon powerhouse closer
to Portage Creek in order to make use of the add it iona1 head estimated
to anount to 55 feet .
. Reservoir operating rule curves .
. Project scheduling and staging concepts. A more detailed analysis of
the staging concept should be undertaken. This should include a
reevaluation of the powerhouse stage sizes and the construction
schedules. In addition, an assessment should be made of the technical,
environmental and economic feasibiaity of bringing the Devil Canyon dam
and powerhouse on-line before the Watana developnent.
2-14
This may be an attractive alternative from a scheduling point of view as it
allows Susitna power to be brought on-line at an earlier date due to the
shorter constr ucti <;m period associ a ted with the Dev i 1 Canyon dam.
The general procedure established during this study for site selection and
plan formulation as outined in Appendix A should be adhered to in
undertaking the above optimization stud11~s.
The engineering studies outlined in Subtdsks 6.07 through 6.31 of the POS
should con.tinue as originally planner! in order to finalize the project
general arrangements and details, and to firm up technical feasibility of
the proposed develOIJllent.
As outlined in the original Task 6.37 study effort, the generation scenario
planning studies should be refined once more definitive project data are
obtained from the stufJies outlined above and the Railbelt generation
alternatives study is completed. The objective of these studies should be
to· refine the assessment of the economic, environmental, and social
feasibility ot the proposed Susitna Basin developnent.
2-15
3 -SCOPE OF WORK
The Scope of Work discussed in this section of the Development Selection Report
includes the development selection studies and preliminary engineering studies
aimed at refining the general arrangements of the selected Watana and Devil
Canyon darn projects. ·
Further details of the Scope of Work may be found in the Acres' POS· (1,2}.
3.1 -Development Selection Studies
These studies constitute Stage 1 of the Task 6 design studies and include the
fo 11 0\-Ji ng:
(a) Review of Previous Studies and Reports (Subtask 6.01)
These activities involve assembling and reviewing all available engineering
data pertaining to Susitna Basin hydropower development. The results of
this work are summarized in Section 4 and are also reported separately in
Reference (3).
(b) Investigate Tunnel Alternatives (Subtask 6.02)
In this subtask conceptual engineering designs of a long power tunnel
alternative to the Devil Canyon dam are produced and evaluated in terms of
economic and environmental impact. This work is summarized in Section 8
and is reported in detail in Reference (4).
(c) Evaluate Alternative Susitna Developments (Subtask 6.03)
This subtask incorporates studies aimed at developing engineering, cast and
environmental impact data at all potential sites within the Susitna Basin
and a series of screening and evaluation exercises to produce a shortlist
of preferred Susitna Basin development options. These studies include the
developm-ent of engineering layouts at several candidate sites within the
basin in order• to improve the accuracy of. capital cost estimates. Computer
models are used to screen out non-economic development plans and to
evaluate power and energy yields of the more promising dam schemes.
This work is described in Section 8. Detailed results are contained in
Appendices D; E, and F.
(d) Hatana and Devi 1 Canyon Staged Development (Subtask 6.06)
As an extension to the engineering layout work described above, several
additional layout studies have been undertaken to investigate the
feasibility of staging dam construction at the larger damsites such as
Watana and High Devil Canyon. Consideration is also given to methods of
staging the mechanical equipment. The results of these studies are
include,d in Section 8.
3-1
(e) Jhermal Generating Resources (Subtask 6.32)
Economic benefits of proposed Susitna Basin ~evelopments are evaluated in
terms of the economic impact on the entire Railbelt electrical generating
system. It is therefore necessary to develop cost .and performance figures
for alternative energy generating resources including thermal and other
potential hydro sites located outside the Susitna Basin. The subtask
involves studies undertaken to develop performance and cost data for a
range of feasible thermal generating options including coal fired steam,
gas turbine, combined cycle and diesel plants.
The results of this subtask are reported in Section 6 and Appendix B.
· (f) Hydroelectric Generating Source (Subtask 6.33)
This subtask involves an extensive screening exercise incorporating
economic and environmental criteria. The aim of this exercise is to
shortlist several potential hydroelectric developments located outside the
Susitna Basin which could supply the railbelt with energy. Conceptual
sketch layouts are produced for the shortlist developments in order to
estimate the capital costs more accurately. Computer models are used to
indicate the power and energy yields.
The result of this work are reported in Section 6 and Appendices C and F,
(g) Environmental Analysis (Subtask 6.34)
This subtask includes the environmental studies necessary to screen the
potential hydroelectric developments outlined in (f) above and to provide
general information on the potential environmental impacts associated with
the thermal generating resources.
The results of these studies are outlined in Sections 6 and 8 and in
Appendices A and C.
(h) Load Management and Conservation (Subtask 6.35)
In order to thorough 1 y assess the economics of tt·e proposed Susi tn a
development plan for a wide range of projected load forecasts it is
necessary to assess the potential impact of possible future local
management and conservation practices. A brief study is undertaken to
determine the impact of a feasible 1 oad management and conservation
scenario and appropriate adjustments are made to energy and 1 oad forecasts
fo.r use in the generation planning studies discussed in Section 5.
(i) Generation Planning (Subtask 6.36)
This subtask involves the systemwide economic analyses undertaken to
determine the economic benefits of vat"'ious Susitna Basin development plans
and alternative all-thermal and thermal-plus-other-hydro generating
scenarios. These latter two scenarios are studied in order to assess the
economic benefit associated with developi.ng the Susitna Basin. A computer
generation planning model is used to undertake these analyses.
3-2
Section 8 and Appendix G outline the results of this work.
(j} Development Selection Repo~~ (Subtask 6.05)
This subtask deals with the production of the report. It also includes a
summary of the load projections prepared by ISER and the power projections
provided by wee in Section 5.
Addition a 1 study work is also carried out to formalize the project
development selection process, i.e. to integrate the results of the studies
outlined above to provide a comprehensive selection process incorporating
economic, environmental and other considerations.
3.2 -fontinued Engineering Studies
As the development selection studies were finalized work continued on
engineering desig~ studies aimed at refining the general arrangements at the
De vi 1 Canyon and Watana sites. These studies i nvo 1 ve t:he production of
alternative general arrangements incorporating rockfill and concrete arch dams
at Watana and several alternative concrete arch dams at Devil Canyon. These
arrangements are casted iLnd evaluated to determine which is the most
appropriate. Design work is carried out on the proposed thin arch dam at Devil
Canyon to ensure that such a structure can safely withstand the anticipated
seismic loading. Extensive use is made of computer stress analysis techniques
in the design studies.
These studies are scoped in Subtasks 6.04, 6.07, and 6.08 and the re~ults are
summarized in Section 9 and Appendix H.
3-3
LIST OF REFERENCES
{1)
(2)
(3)
( 4)
Acres American Incorporated, Susitna Hydroelectric Project -Plan of Study,
Prepared fer the Alaska Power Authority, February, 1980.
Acres American Incorporated, Susitna Hydroelectric Project -Plan of Study,
Revision 1, Prepared for the Alaska Power Authority, September, 1981.
Acres American Incorporated, Susitna Hydroelectric Project -Review of
Previous Studies and Reports, Prepared for the Alaska Power Authority,
February~ 1981 ..
Acres American Incorporated, Susitna Hydroelectric Project -Investigate
Tunnel Alternative, Clos(~out Report prepared for the Alaska Power
Authority, April, 1981.
3-4
~---------
4 -PREVIOUS STUDIES
In this section of the report a summary is presented.of studies undertaken by
the WRPS (formerly the USBR), the COE and others over the period 1948 through
1979.
4.1 -Early Studies of Hydroelectric Potential
Shortly after World War II ended the USBR conducted an initial investigation of
hydroelectric potential in Alaska, and issued a report of the results in 1948.
Responding to a recommendation made in 1949 by the nineteenth Alaska territorial
legislature that Alaska be included in the Bureau of Reclamation program, the
Secretary of Interior provided funds to update the 1948 work. Th~ resulting
report, issued in 1952, recognized the vast hydroelectric potential within the
territory and placed particular emphasis on the strategic location of the
Susitna River ·between Anchorage and Fairbanks as well as its proximity tc the
connecting Railbelt {See Figures 1.1 and 4.1).
A series of studies was commissioned over the years to identify dam sites and
conduct geotechnical investigations. By 1961, the Department of the Interior
proposed authorization of a two dam pov.rer system involving the Devil Canyon and
the Denali sites (F·igure 4 .. 1). The definitive 1961 report \ltas subsequently
updated by the Alaska Power Administration (at that time an agency of the Bureau
of Reclamation) in 1974, at which time the desirability of proceeding with
hydroelectric development was reaffirmed.
The COE was also active in hydropower investigations in Alaska during the 1950~s
and 1960's, but focused its attention on a more ambitious development at Rampart
on the Yukon River., This project was capable of generating five times as much
electric energy as Susitna annually. The sheer size and the technological
challenges associated with Rampart captured the imagination of supporters and
effectively diverted attention from the Susitna Basin fot" more than a decade.
The Rampart report was finally shelved in the early 1970's because of strong
environmental concerns and the uncertainty of marketing prospects for so much
energy, particularly in light of abundant natural gas whi.ch had been discovered
and developed in Cook Inlet~
<
The energy crisis precipitated by the· OPEC oi 1 boycott in 1973 provided some
further impetus for seeking development of renewable resources. Federal funding
was made available both to complete the Alaska Power Administration's update
report on Susitna in 1974 and to launch a prefeasibility investigation by the
COE. The State of Alaska itself commissioned a reassessment of the Susitna
Project by the Henry J. Kaiser Company in 1974.
Although the gestation period for a possible Susitna Project has been lengthy,
Federal, State, and private or·ganizations have been virtually unanimous over the
years in recommending that the project proceed& Salient features of the various
reports to date are outlined in the following sections.
4 ,
-I
4. 2 -U.S. Bureau of Reel amation --1953 Study (1)
The USSR 1952 report to the Congr~ss on Alaska's overall hydroelectric poten-
tial was followed shortly by the first major study of the Susitna Basin ·in-1953.
Ten dam sites were identified above the railroad crossing a.t Gold Creek (see
also Figure 4-1):
-Gold Creek
-01 son
= De vi 1 Canyon
-Oevi 1 Creek
-Watana
-Vee
-Maclaren
-Denali
-Butte Creek
-Tyone (on the Tyone R~ver)
Fifteen more sites were considered below Gold Creek. However, more attention
has been feGuse.d over the years on the Upper Susitna Basin where the topography
is better· sui"Led to dam construction and where less impact on anadromous fisher-
ies ts expected. Field reconnaissance eliminated half the original Upper Basin
list and further USBR consideration centered on Olson, Devil Canyon, Watana, Vee
and Denali. A11 of the USBR studies since 1953 have regarded these sites as the
most appropriate for further investigation.
4.3 -U.S. Bureau of Reclamation -1961 Study (2)
In 1961 a more detailed feasibility study resulted in a recommended five stage
development plan to match the load growth curve as it was then projected. Devil
Canyon was to be the first development--a 635 feet high arch dam with an
installed capacity of about 220 MW. The reservoir formed by the Devil Canyon
dam alone would not store enough water to permit higher capacities to be econom-
ically installed since long periods of relatively low flow occur in the wir~er
months. The second stage waul d have increased storage capacity by adding an
earthfill dam at Denali in the upper reaches of the basin9 Subsequent stages
involved adding generating capacity to the Devil Canyon dam. Geotechnical
investigations at Devtl Canyon were more thorough than at Denali. At Denali~
test pits were dug, but no drilling occurred.
4.4 -Alaska Power Administration -1974 (3)
Little change from the basic USBR-1961 five stage concept appeared in the 1974
report by .the Alaska Power Administration. This later effort offered a more
sophisticated design, provided new cost and schedule estimates, and addressed
marketing, economics, and environmental considerations.
4. 5 -,Kaiser Propos a 1 for Deve 1 opment ( 4}
The Kaiser study, corrmissioned by the Office of the Governor in 1974, proposed
that the initial Susitna development consist of a single dam known as High Dev1l
Canyon (See Figure 4.1). No field investigations were made to confirm the tech-
nical feasibility of the High Devil Canyon location because the funding level
was insufficient for such efforts. Visual observations suggested the site
4-2
was probably favorable. The USBR had always been uneasy about foundation condi-
tions at Denali, but had to rely upon the Denali reservoir to provide storage
during long periods of low flow. Kaiser chose to avoid the perceived uncertain-
ty at Denali by proposing to build a rockfill dam at High Devil Canyon which, at
810 feet, would create. a large enough reservoir"' to overcome the storage problem.
Although the selected sites were different, the COE reached a similar conclusion
when it later chose the high dam at Watana as the first to be constructed.
Subsequent developments suggested by Kaiser included a downstream dam at thE
Olson Site and an upstream dam at Susitna III (see Figure 4.1). The information
developed for these additional dams was confined to estimating energy potential.
As in the COE study, future development of Denali remained a possibility if
foundation conditions were found to.be adequate and if the value of additional
firm energy provided economic justification at some later date.
·Kaiser did not regard the develop!l!ent of an energy consumptive aluminum plant as
necess~ry to economically justify its proposed project.
4.6 -u.s. Army Corps of Enaineers -1975 and 1979 Studies (5,6)
The most comprehensive study of the Upper Susitna Basin to date was completed in
1975 by the COE. A total of 23 alternative developments were analyzed, includ-
ing those proposed by the USBR as well as consideration of coal as the primary
energy source for Railbelt electrical needs. Tne COE agreed that an arch dam at
Devil Canyon was appropriate, but found that a high dam at the Watana site would
form a large enough reservoir for seasonal storage and would permit continued
generation during low flow periods.
The COE recommended an earthfill dam at Watana with a height of 810 feet. ln
the longer term, development of the Denali site remained a possibility which, if
constructed, would increase the amount of firm energy available, even in very
dry years.
An ad-hoc task force \o.Jas created by Governor Jay Hammond upon completion of the
1975 COE Study. This task force recommended endorsement of the COE request for
Congressional authorization, but pointed out that extensive further studies,
particularly those dealing with environmental and socioeconomic questions~ were
necessary before any construction decision could be made.
At the Federal level, concern was expressed at the Office of Management and
Budget regarding the adequacy of geotechni ca 1 data at the Watana site as we 11 as
the validity of the economics. The apparent ambitiousness of the schedule and
the feasibility of a thin arch dam at Devil Canyon were also questioned. Fur-
ther investigations were funded and the COE produced an updated report in 1979.
Devil Canyon and Watana were reaffirmed as appropriate sites, but alternative
dam types were investigated. A concrete gravity dam was analyzed as an alterna-
tive for the thin arch dam at Devil Canyon and the Watana dam was changed from
earthfill to rockfill. Subsequent cost and schedule estimates still indicated
economic justification for the project.
"'
4-3
LEGEND
~
TYONE. & DAMSITE
5 0 5 15
E I I I
SCALE IN MILES
DAMSITES PROPOSED BY OTHERS ./-..J---v
.,J
/
J
,... -------------/
FIGURE 41 IIIR I
LIST OF REFERENCES
(1). u.s. Department of the Interior, Bureau of Reclamation (Alaska District),
District Manager's Reconnaissance Report of August, 1952 on Susitna River
Basin: A Report on the Potential Development of Water Resources in the
Susitna River Basin of Alaska, 1952.
(2) u.s. Department of the Interior, Bureau of Reclamation (Alaska District),
Devil Canyon Project, Alaska: Report of the Commissioner of Reclamation
and Supporting Reports, 1960.
(3} Alaska Power Administration, Devil Canyon Status Report, Juneau, Alaska,
May, 1974.
( 4) H. J. Kaiser & Company, Reassessment Report on Upper Susitna River_
Hydroelectric Development for the State of Alaska, September, 1974.
(5) u.s. Department of the Army, Corps of Engineers (Alaska District),
Hydroelectric Power and Related Purposes: Southcentral Railbelt Area,
Alaska, Upper Susitna River Basin -Interim Feasibility Report, Anchorage~
Alaska, 1975.
( 6) u.S. Department of the Army, Corps of Engineers \A 1 ask a District),
Hydroelectric Power and Related Purposes: Southcentral Railbelt Area,
Alaska, Upper Susitna River Basin-Supplementary F~asibility Report,
Anchorage, Alaska, 1979.
4-5
'··
5 -RAILBELT LOAD FORECASTS
5.1 -Introduction
The feasibility of a major hydroelectric project depends in part upon the extent
which the available capacity and energy are consistent with the needs of the
market to be served by the time the project comes on line. Attempting to fore-
cast future energy demand is a difficult process at best; it is therefore parti-
cularly important that this exercise be accomplished in an objective manner ..
For this reason APA and the State of Alaska jointly awarded a separate contract
to ISER to prepare appropriate projections· for the Alaska Railbelt region ..
Section 5 presents a review of the economic scenarios upon which the ISER fore-
casts were based and a discussion of the forecasts developed for use in gener-
ation planning studies.
5.2 -Electricity Demand Profiles
This section reviews the historical growth of e'!ectricity consumption in the
Ra·ilbelt and compares it to the national trend. Railbelt electricity consump-
tion is then disaggregated by regions and by end-use sectors to clarify past
us age patterns.
{a) Historical Trends
Between 1940 and 1978, electricity sales in the Railbelt grew at an average
annual rate of 15.2 percent. This growth was roughly twice that for the
nation as a whole. Table 5.1 shows U.S. and Alaskan annual growth rates
for different periods between 1940 and 1978. The historical growth of
Railbelt utility sales from 1965 is illustrated in Figure 5.1.
Although the Railbelt growth rates consistently exceeded the national aver-
age, the gap has been narrowing in 1ater years due to the gradual maturing
of the Alaskan economy. Growth in the Railbelt has exceeded the national
average for two reasons: population growth in the Railbelt has been higher
than the national rate, and the proportion of Alaskan households served by
electric utilities was lower than the U.Sp average so that some growth in
the number of customers occurred independently of population growth. Table
5.2 compares U.S. and Alaskan growth rates in the residential and commer-
cial sectors.
(b) Regional Demand
Electricity demand in the Railbelt, disaggregated by regions, is shown in
Table 5.3. During the period from 1965 to 1978, Greater Anchorage
accounted for about 75 percent of Railbelt electricity consumption followed
by Greater Fairbanks with 24 percent and Glennallen-Valdez with 1 percent.
The pattern of regional sharing during this period has been quite ,stable
and no discel"nible trend in regional shift has emerged. This is mainly a
result of the uniform rate of economic development in the Alaskan
Railbe1t ..
5-1
(c) End-Use Consumption
Railbelt electricity consumption by major end-use sector is shown in Table
5.4. In the residential sector, electricity consump~ion is largely attrib-
uted to space heating; utilities such as refrigerators, water heaters,
lights and cooking r·anges rank next in order of usage. In the commer-
cial-industrial-gover·nment sector, end-use consumption is less clear
because of a lack of data; however, it is reasonable to assume that elec-
tricity is used ma·inly for lighting, space heating, cooling and water
heating. Consumption in the miscellaneous sector is attributed mainly to
; street 1 ighting and usage in second homes.
The distribution of electricity consumption in these end-use sectors has
been fairly stable. By 1978, the commercial-industrial-government and
residential sectors accounted for 52 percent and 47 percent respectively.
In contrast, the 1978 nationwide shares were 65 percent and 34 percent
respective ly{l).
5.3 -ISER Electricity.Consumption Forecasts
As outlined in Section 3, the electricity consumption forecasts were undertaken
by ISER(1). This section briefly discusses the methodology used by ISER to
estimate electric ener£\Y sales for the Railbelt, and summarizes the results
obtained. ·
(a) Methodology
The ISER electricity demand forecasting model conceptualized in computer
logic the linkage between economic growth scenarios and electricity con-
sumption. The output from the model is in the form of proJected values of
electricity consumption for each of the three geographical .areas of the
Railbelt (Greater Anchorage, Greater Fairbanks and Glennallen-Valdez) and ·
is classified by final use {i.e., heating, washing, cooling, etc.) and con-·
suming sector (commercial, residential, etc). The model produces output on
a five-year time basis from 1985 to 2010, inclusive ..
The ISER model consists of several submodels linked by key variables and
driven by policy and technical assumptions and state and national trends.
These submodels are grouped into four economic models which forecast future
levels of economic activity and four electricity consumption models which
forecast the associated electricity requirements by consuming sectors. For
two of the consuming sectors it was not possible to set up computer models
and simplifying assumptions \-Jere made. The models and assumptions are
·described below.
(i) Economic Submodels
-The MAP Econometric Mode 1
MAP is i.m econometric model based on forecasted or assumed 1 eve 1 s
of national economic trends, State government activity, and
developments in the Alasl<a resource sector. These economic. indi-
cators are translated into forecasted levels· of statewide popul a-
tion by age and sex, employment by industrial sector, and income.
5-2
-The Household Formation Model
The household formation model groups individuals into household
units on the basis of national and state demographic trends. The
output is the forecast number of household heads by age and sex?
which is in turn an input to the housing stock and electricity·
consumption models.
-Regional Allocation Model
This model disaggregates MAP's projections of population and
employment into regions of the Railbelt. The model uses econo-
metric techniques to structure regional shares of state popula-
tion, the support sector, and government employment.
Housing Stock Model
The housing stock model utilizes the output from the household
formation model, the regional ·population information from the
regional allocation model} and the results of an independent
survey on housing choice. These outputs are combined to protluce
the number of housing units by type (e.g. single family, duplex,
multifamily, etc.) and by region for each of the forecast years.
(ii) Electricity Consumption Submodels
These submodels are structured to determine electricity requirements
for various demand components:
-Residential Non-space Heating Electricity Requirements
This model estimates electricity requirements for household
appliances utilizing the following information:
• number of households
. appliance saturation rate
• fuel mode split
. average annual consumption of appliance
• average household size
Residential non-space heating electricity requirements are
obtained by summing the electricity requirements of all appli-
ances.
-Residential Space Heating
This modPl estimates space heating electricity requirements for
four types of dwelling units: single family, duplex, multi-
family, and mobile home. The space heating electricity require-
ment for each type of dwelling unit is calculated as the product
of the number of dwelling units, fuel mode split and specified
average levels of consumption.
5-3
-Commercial-Industrial-Government
Total electricity requirements for the commercial-industrial-
government sector are defined as the product of non-agricultural
wage and salary employment and average electricity consumption
per employee. Electricity consumption per employee is a function
of time and application of conservation standards. This implies
that new electricity users in this .sector will have different
electricity requirements than previous customers.
-Mi see 11 aneous
This model estimates two remaining sectors of electricity con-
sumption: i.e. street lighting and recreational homes.
(iii) Consumption Sectors Not Modeled
Electricity requirements were not modeled for two sectors of demand:
Mi 1 itary
For many reasons, including a lack of historical data, no model
is included to correlate military electricity consumption with
causal factors. Hence, future electricity requirements for the
military are assumed to be the same as the current level.
-Self-Supplied Industrial
No model is included to project future self-generated electricity
for industry. Existing users are identified and current
electricity consumption determined for APA sources. New users
and future consumption levels ·are identified from economic
scenari o.s.
(b) Assumptions
To make these models operational, a number of additional assumptions are
incorporated:
The electricity market is presently in a state· of relative equil ibriun
ex.cept for Fairbanks where a shift away from electric space heating is
underway. This equilibrium is expected to remain in effect throughout
the forecast period because of relatively constant fuel price ratios.
The price of energy relative to other goods and services will continue
to rise.
a
Rising real incomes will act to increase the demand for electricity.
~
Federal policies will be effective in the area of appliance energy con-
servation, but will have a much smaller impact on building stock thermal
efficiencies.
5-4
-No State conservation policies directed exclusively toward electricity
will be implemented.
-No sign~ficanL State policies designed to alter the price or availabil-
ity of alternative fuels will be implemented.
No new electricity technologies will be introduced.
In terms of residential appliances:
·•
Saturation rates will follow national trends;
For some appliances, reduced household size will act to reduce
average electricity requirements; .
Consumption is a function of the appliance scrapping rate as the
average age affects efficiency;
Unspecified appliance consumption will increase to accommodate the
Possibility of new domestic electricity applications.
\)
In term~ of residential space heating:
A slight trend toward single family homes is projected;
Average housing unit size will continue to grow;
Natural gas availability will not significantly increase;
Space heating alternatives such as oil, wood or coal wiil not greatly
affect aggregate space heating demand;
No significant increase in the number of heat pumps will occur.
In terms of commercial-industrial-government use:
Employment will grow more rapidly than the population;
No major energy conservation measures are anticipated;
The distribution of electricity end-uses will not shift
significantly.
-Miscellaneous utility sales {street lighting and second home use) will
grow at rates consistent with predicted total utility sales.
(c) Forecasting Uncertainty
To adequately address the uncertainty associated with the prediction of
future demands, a number of different economic growth scenarios were
considered. These were formulated by alternatively combining high, moder-
ate and low grov1th rates in the area of special projects and industry with
State government fiscal policies aimed at stimulating either high, moderate
or low growth. This resulted in a total of nine potential growth scenarios
for the State. In addition to these scenarios~ ISER also considered the
potential impact of a price reduced shift towards increased electricity
demand. As outlined below, a short list of six future scenarios was
selected.. These concentrated around the mid-range or 11 most likely11 esti-
mate and the upper and lower extremes.
5-5
(d) Forecast Results
I • ) \1 Base Case
The ISER forecast which incorporates the combination of moderate ~
economic grnwth and moderate government expenditure is considered to
be the 11 most likely" load forecast. This has been identified for
the purpose of this study as the "Base Case Forecast". The results
of this forecast are presented in Table 5.5 and indicate that
utility sales for the Railbelt will grow from the 1980 level of 2390
GWh to 7952 GWh in 2010, representing an average annual growth rate
of 4.09 percent. Over the period of the forecast, tpe highest
growth rate occurs from 1990 to 2000 at 4 .. 76 percent, followed by a
decline to 3.33 percent during the 2000 to 2010 period.
(ii) Range of Forecasts
In addition to the base case, the ISER results incorporate a higher
and lower rate of economic growth coupled with moderate government
expenditure, and they also incorporate the case where a shift to
electricity takes place. These forecasts do not provide a c·omplete
envelope of potential growth scenarios because the impacts of high
industrial growth/high government expenditure and lpw industrial
growth/low government expenditure on electricity demand have not
been included. Estimates of these impacts have been computed by the
method of proportionality as approximations to the model runs. A
summary of aggregate Railbelt electricity growth for the range of
scenarios is presented in Table 5.6 and in Figure 5.2. The medium
growth rate of 4.1 percent is shown to be bounded by lower and upper
limits of 2.8 percent and 6.1 percent respectively. In comparison,
historical electricity demand in the Railbelt has increased by 11
percent.
5.4 -Past Projections of Railbelt Electricity Demand
A number of electricity projections have been developed in the past. The dis-
cussion here is confined to work conducted since 1975 in order to compare ISER's
forecasts with previous wcn··k and to rationalize any differences that occur.
Forecasts of electric povter requirements developed since 1975 (excluding ISER 1 s
latest forecast) are summarized in Table 5.7. A cursory examination indicates
that differences which occur in the early years progressively increase within
the forecast period. The performance of these forecasts can be ascertained by
comparing them to 1980 utility sales. Table 5.8 snows the rercent error in the
forecasted growth rate to 1980. As can be seen, all of the forecasts signifi-
cantly overestimated 1980 consumption.
These forecasts are also significantly different from those developed recent1y
by ISER; the differences are mainly attributed to assumptions concerning
economic growth and electricity consumptior rates. Although the economic growth
a-:;sumptions incorporated in previous studies have Vdried wid£1y, they have been
generally more optimistic with respect to the type, size and timing of projects
and other economic events. This has ~onsequently resulted in higher projections
of economic activity compared to the recent ISER study. ·
5-6
Electricity consumption rates in the ISER studies are generally lo~'/er than those
in previous studies. This is essentially because ISER has been the first to
incorporate estimates .of applian~e saturation rates, end-use patterns and con-
servation measures.
5.5 -Uemand Forecasts
(a) Appro2_£h
The overall aptroach to derivation of the peak demand forecasts for the
Railhelt Region was to examine the available historical data with regard to
the generation of electrical energy and to apply the observed generation
patterns to existing sales forecasts. Information routinely supplied by
the Railbelt utilities to the.Federal Energy Regulatory Commission was
uti l i zed to determine these load patterns.
(b) Load Patterns _, ..
The analysis of load patterns emphasized the identification of average pat-
terns over the 10-year period from 1970 to 1979 and did not consider trends
or changes in the patterns with time. Generally, the use of average values
was preferred as it reduced the impact of yearly variations due to variable
weath~r conflitions and outages. In any event, it was not possible to
detect any patterns in the available data.
The average houriy distribution of generation for the first weeks of April,
August and December was used to determine the typical average load pattern
for the various utilities. As a result of the relatively limited data
base, the calculated load duration curve would be expected to show less
variation than one computed from a more complete oata base resulting in an
overestimation of the load factor. In addition, hourly data also tend to
average out actual peak demands occurring \vithin a time interval of less
than one hour. This could also lead to overestimation of the load factor.
It is~ howeverg believed that the accuracy achieved~is adequate for these
studies,_ particularly in light of the relatively much greater uncertainties
associated with the load forecasts.
(c) Sales Allocation
Although the above load data are available by utility, the kWh sales fore-
casts are based on service area alone.. The kWh sales data \'-Jere allocated
to the individual utilities utilizing a predicted mix of consumer cate-
gories in the area and the curr""ent mix of sa 1 es by consumer category for
the utilities serving the area.
(d) Peak Loads
The two data sets were combined to determine composite peak loads for the
Railbelt area.
5-7
The first step involved an adjustment to the allocated sales to reflect
losses and energy unaccounted for. The adjustment was made by increasing
the energy allocated to each utility by a factor computed from historical
sales and generation levels. This resulted in a gross energy generation
for each utility.
The factors determined for the monthly distribution of total annual genera-
tion were then used to distribute the gross generation for each year. The
resulting hourly loads for each utility were adaed together to obtain the
total Railbelt system load pattern for each forecast year. Table 5.9
summarizes the total energy generation and the peak loads for each of the
low, medium, and high ISER sales forecasts, assuming moderate government
expenditure.
The load factors computed in this study average seven percentage points
higher than the average load factors observed in the four utilities over
the 10-year period.
5.6 -Potential for Load Management and Energy Conservation
Utilities nationwide are currently paying increasing attention to the implemen-
tation of load management and conservation measures in an attempt to reduce or
shift peak load and to reduce energy demand. Load management is defined as the
"shifting 11 and corresponding reduction of peak demands and the alteration of
daily load shapes by means of appropriate measures. Although some load manage-
ment techniques can result in a slight increase in daily energy demand, the
objective is essentially to accomplish a reduction of peak demand with no signi-
ficant difference in total energy demand. Load management may generally be
achieved by one of two methods: direct control, in which the utility controls
the end-use devices; or indirect control, in which price incentives are used to
motivate load shifting by the consumer. Conservation is defined as a net reduc-
tion in energy demand by means of appropriate measures, with a corresponding
reduction in peak demand.
The potential benefits of power demand control and reduction measures require
careful evaluation before implementation on a major scale. A considerable
amount of research and development work has been undertaken in the Lower 48 to
develop methods and cost strategies, and to assess the potential impact of such
strategies on demand. As a result of this work, load management and energy con-
servation concepts have either been implemented or are being planned by many
utilities. The anticipated effects on the growth of future peak load and energy
consumption in the utility systems have been included in their forecasts. Cur-
rently in Alaska, one utility, Anchorage Municipal Light and Power, has insti-
tuted an experimental time-of-day rate for electricity.
Although conservation is essentially accomplished by a reduction in demand, it
may also be regarded as a means of diverting available energy to other uses, or
creating a 11 new" source of energy. A recent study by the Alaska Center for
Policy Studies (2) indicated that conservation was the most economically attrac-
tive source of new energy available to the Railbelt area. This conclusion was
based on evidence from existing weatherization programs and projections from the
Alaska Federation for Community Self Reliance in Fairbanks. However, the total
amount of energy that can be made available by such means is relatively small
compared to the total Kailbelt system energy demand up to the year 2010.
5-8
The ISER forecasts incorporated the impacts of certain energy conservation
measures, but did not include any load management. In this study, opportunities
for implementation of additional progrillliS of intensified conservation and load
management measures are considered in the generation planning studies. These
are discussed in more dt. ·,ail in the following section.
5.7 -Load Forecasts Used for Generation Planning Studies
This.section outlines the adjustments that were made to produce the total Rail-
belt system electricity forecasts to be us~d in the generation planning studies
described in Section 8.
(a) Adjusted ISER Forecasts
Three ISER energy forecasts were considered in generation planning studies
(see Table 5.6). These include the base case (MES-~~) or medium forecast,
a 1ow and a high forecast. The.low forecast is that corresponding to the
low economic growth as proposed by ISER with an adjustment for low govern-
ment expenditure {LES-GL). The high forecast corresponds to the ISER high
economic growth scenario with an adjustment for high government expenditure
tHES-GH).
The electricity forecasts summarized in Table 5.9 represent total utility
generation and include projections for self-supplied 1ndustrial and mili-
tary generation sectors. Included in these forecasts are transmission and
distribution losses in the range of 9 to 13 percent depending upon the
generation scenario assumed~ These forecasts, ranging from 2.71 to 4.7b
percent average annual growth, were adjusted for use in generation planning
studies.
The self-supplied industrial energy primarily involves drilling and off-
shore operations and other activities which are not likely to be connected
into the Railbelt supply system. This component, which varies depending
upon generation scenario, was therefore omitted from the forecasts used for
planning purposes.
The military is likely to continue purchasing energy from the general mar-
ket as long as it remains economic. However, much of their generating
capacity is tied to district heating systems which would presumably· contin-
ue operation. For study purposes, it was therefore assumed that 30 percent
of the estimated military generation would be supplied from the grid
system.
The adjustments made to power and energy forecasts for use in self-supplied
industrial and military sectors are reflected in Table 5.10 and in Figure
5.3 The power and energy values given in Table 5.10 are those usea in the
generation planning studies. Annual growth rates range from 1.99 to 5.96
percent for very low and high forecasts wi.tn a medium generation forecast
of 3.96 percent.
{b) Forecast Incorporating Load Management
and Conservation
In order to evaluate generation plans under extremely low projected energy
growth rates, the 1 ow forecast was further adjusted downward to account for
add·ltional load management and energy conservation. The results of this
scenario also appear on Table 5.10.
5-9
-ISER Conservation Assumptions
For the residential sector, ISER assumed the federally-mandated efficien-
cy standards for electrical home appliances would be enforced from 1981
to 1985 but that target efficiencies would be reduced by 10 percent.
Energy saving due to retrofitting of homes was assumed to be confined to
single family residences and to occur between 1980 and 1985. Heating
energy consumption was assumed to be reduced by 4 percent in Fairbanks, 2
percent in Anchorage and between 2 and 4 percent in the Glennallen-Valdez
area. Enforcement of mandatory construction or performance standards for
new housing was assumed in 1981 with a reduction of the heat load for new
permanent home construction by 5 percent.
In the commercial-industrial-government sector, it was assumed by ISER
that electricity requirements for new construction would be reduced by 5
percent between 1985 and 1990 and by 10 percent during the period 1990 to
2000. It was assumed that retrofitting measures would have no impact.
-Impacts of Recent Legislation
The National Energy Conservation Policy Act includes a variety of incen-
tives and mandates for energy conservation and alternative energy use by
individuals, state government and business. The new programs consist of
energy audits of residential customers and public buildings, insulation
and retrofitting of homes through loan and grant programs, improvement of
energy efficiency of schools and hospitals, and use of solar energy.
The Public Utilities Regulatory Policies Act (PURPA) of November 9, 1978,
requires state public utility commissions to consider certain rate-making
standards for utilities if they have sales in excess of 500 million kilo-
watt hours. The established standards to be considered are:
. Rates to reflect cost of service;
. Abolition of declining block rates;
. Time-of-day rates;
. Seasonal rates.
Both Chugach Electric (CEA) and Anchorage Municipal Light and Power
Department (AMLPD) are affected by the provisions of PURPA regarding rate
and service standards for electric utilities. According to the report by
the Alaska Center for Policy Studies (2), the Alaska Public Utilities
Commission (APUC) intends to deal with the rate and load management
considerations called for by PURPA in 1981.
-Study Assumptions
The programs of energy conservation and load management measures that
could be implemented in addition to those included in the ISER forecast
are the following:
5-10
. Energy programs provided for in the recent state energy conservation
legislation;
. Load management concepts now tested by utilities, including rate
reform, to reflect incremental cost of service and load controls.
These measures could decrease the growth rate of energy and winter peak
projected in the ISER forecast and the forecasts used in generation plan-
ning. The impacts would be mainly in the residential sector.
The impact of state energy conservation legislation has been evaluated in a
study by Energy Probe (3) which indicated that it could reduce the amount
of electricity needed for space heating by 47 percent. The total growth
rate in electricity demand over the 1980-2010 period would drop from an
average of 3.98 percent per annum (projected by ISER in the MES-GM fore-
cast), to 3.49 percent per annum. Energy Probe indicated that the electri-
cal energy growth rate could be reduced even further to 2.70 percent per
annum with a conservation program more stringent than that presently
contemplated by the State legislature.
The low forecast case assumed above incorporates an annual growth rate of
2.71 percent. This rate would be reduced with enforcement of energy con-
servation measures more intensive than those presently in the State legis-
lature. An annual growth rate of 2.1 percent was judged to be a reasonable
lower limit for electrical demand for purposes of this study. This
represents a 23 percent reduction in growth rate which is similar to the
reduction developed in the Energy Probe study.
The implementation of load management measures would result in an addition-
al reduction in peak load demand. The residential sector demand is the
most sensitive to a shift of load from the peak period to the off-peak
period. Over the 1980-2010 period, an annual growth rate for peak load of
2.73 percent was used in the low forecast case. With load management
measures such as rate reform and load controls, this growth rate could be
reduced to an estimated 2.1 percent. The annual load factor for year 2010
would be increased from 62.2 percent in the low forecast to 64.4 in the
lowest case.
5-11
TABLE 5.1 -HISTORICAL ANNUAL GROWTH RATES OF ELECTRIC UTILITY SALES
Anchorage and Fairbanks
Period u.s. Areas
1940 -1950 8.8% 20.5%
1950 -1960 8.7% 15. 3~~
1960 -1970 7 .3~~ 12.9%
1970 -1978 4.6% 11.7%
1970 -1973 6. 7~~ 13.1%
1973 -1978 3.5% 10.9%
1940 -1978 7.3% 15.2%
5-12
TABLE 5.2 -ANNUAL GROWTH RATES IN UTILITY CUSTOMERS AND CONSUMPTION PER CUSTOMER
Greater Anchorage Greater Fairbanks u.s.
Customers Consumption per Customers Consumption per Customers Consumption per
(Thousands) Customer (MWh) (Thousands) Customer (MWh) (Millions) Customer (MWh)
Residential
1965 2.7 6.4 8.2 4.8 57.6 4.9
1978 7.7 10.9 17.5 10.2 77.8 8.8
Annual Growth
Rate (%) 8.4 4.2 6.0 6.0 2.3 4.6
(J1
I ._.
w Commercial
1965 4.0 1.3 7.4
1978 10.2 2.9 9.1
Annual Growth
Rate (%) 7.5 6.4 1.6
TABLE 5.3-UTILITY SALES BY RAILBELT REGIONS
Greater Anchorage Greater Fa1rbanks Glennallen-Qaldez Ra1lbe!E Iota!
1 1 1 1
Sales No. of Sales No. of Sales No. of Sales No. of
Regional Customers Regional Customers Regional Customers Custorrers
Year GWh Share (Thousands) GWh Share (Thousands) GWh Share (Thousands) GWh (Thousands)
1965 369 78% 31.0 98 21% 9.5 6 1% .6 473 41.1
1966 415 32.2 108 9.6 NA NA 523 41.8
1967 461 34.4 66 NA NA NA 527 34.4
1968 519 39.2 141 10.8 NA NA 661 30.0
1969 587 42.B 170 11.6 NA NA 758 54.4
1970 684 75% 46.9 213 24% 12.6 9 1% .8 907 60.3
1971 797 49.5 251 13.1 10 .9 1059 63.5
1972 906 54.1 262 13.5 6 .4 1174 68.0
1973 1010 56.1 290 13.9 11 1.0 1311 71.0
1974 1086 61.8 322 15.5 14 1.3 1422 78.6
1975 1270 75% 66.1 413 24% 16.2 24 1% 1.9 1707 84.2 01 1976 1463 71.2 423 17.9 33 2.2 1920 91.3 1 ..... 1977 1603 81.1 447 20.0 42 2.1 2092 103.2 .,.
1978 1747 79% 87.2 432 19% 20.4 38 2% 2.0 2217 109.6
Annual
Growth 12.7% 8.2% 12.1% 6.1% 13.9% 9.7'% 12.6% 7.8%
NOTES:
( 1) Includes residential and commercial users only, but not miscellaneous users.
Source: Federal Energy Regulatory Commission, Power System Statement (_).
NA: Not Available.
TABLE 5.4-RAILBELT ELECTRICITY END-USE CONSUMPTION (GWh)
Commercial-Industrial
Year Residential -Government Miscellaneous
1965 214 248 9
1966 241 275 8
1967 208 241 8
1968 294 355 11
1969 339 407 12
1970 402 489 14
1971 478 555 25
1972 542 613 17
1973 592 698 19
1974 651 749 20
1975 790 886 28
1976 879 1012 26
1977 948 1117 21
1978 1029 1156 27
Average
Annual
Growth 12.8% 12.6% 8.8%
% of Annual
Consumetion
1965 45% 53% 2%
1970 44% 54% 2%
1975 46% 52% 2%
1978 47% 52% 1%
5-15
TABLE 5.5 -BASE CASE FORECAST (MES-GM)1 (GWh)
0£1!1£~ 5ales to ~II ~onsum1ng Sectors Sales M111tary Self-Supp!J.ed
Glennallen-Net Industry Net
Year Anchorage Fairbanks Valdez Total Utilitl Generation Generation
19BO 1907 446 37 2390 334 414
1985 2438 669 64 3171 334 571
1990 2782 742 75 3599 334 571
1995 3564 949 88 4601 334 571
2000 4451 1177 102 5730 334 571
2005 5226 1397 119 6742 334 571
2010 6141 1671 140 7952 334 571
Average
Annual Growth
Rate (%)
1980-1990 3.85 5.22 7.32 4.18 o.o 3.27
01 1990-2000 4.81 4. 72 3.12 4.76 0.0 o.o
I 2000-2010 3.27 3.57 3.22 3.33 o.o 0.0 ,_.
1980-2010 3.85 4.50 4.54 4.09 o.o 1.08 "'
NOTES:
(1) Reproduced from ISER' s ( -) Medium Economic Growth/Moderate Government Expenditure Scenario
(without price induced shift to electricity).
V1
I ,_, ....,
TABLE 5.6-SUMMARY OF RAILBELT ELECTRICITY PROJECTIONS
Utilit~ Sales to All Consuming
LES-GL 1 MES-GM
Year Bound LES-GM (Base Case)
1980 2390 2390 2390
19B5 2798 2921 3171
1990 3041 3236 3599
1995 3640 3976 4601
2000 4468 5101 5730
2005 4912 5617 6742
2010 5442 6179 7952
Average Annual
Growth Rate (%)
1980-1990 2.44 3.08 4.18
1990-2000 3.92 4.66 4.76
2000-2010 1.99 1.94 3.33
1980-2010 2.78 3.22 4.09
NOTES:
Lower Bound = Estimates for LES-GL
Upper Bound = Estimates for HES-GH
LES = Low Economic Growth
MES = Medium Economic Growth
HES = High Economic Growth
GL = Low Government Expenditure
GM = Moderate Government Expenditure
GH = High Government Expenditure
MES-GM
with Price
Induced Shift
2390
3171
3599
4617
6525
8219
10142
4.18
6.13
4. 51
4.94
Sectors
HES-GM
2390
3561
4282
5789
7192
9177
11736
6.00
5.32
5.02
5.45
(1) Results generated by Acres, all others by ISER (_).
(GWh)
HES-GH 1
Bound
2390
3707
4443
6317
8010
10596
14009
6.40
6.07
5.75
6.07
Military Net
Generation (GWh)
I'ES-GM
(Base Case)
334
334
334
334
334
334
334
o.o
o.o
o.o
0.0
LES-GM
414
414
414
414
414
414
414
0.0
0.0
o.o
0.0
Self-Supplied
Industry Net Generation (GWh)
MES-GM
(Base Case)
414
571
571
571
571
571
571
3.27
0.0
0.0
1.08
MES-GM
with Price
Induced Shift
414
571
571
571
571
571
571
3.27
o.o
o.o
1.08
HES-GM
414
847
981
981
981
981
981
9.0
0.0
0.0
2.92
'-" I .....
00
TABLE 5.7 -SUMMARY OF RECENT PROJECTIONS OF RAILBELT ELECTRIC POWER REQUIREMENTS (GWh)
Study Number/Source
1. South Central Railbelt Area, Alaska
Interim Feasibility Report: Hydro-
electric Power and Related Purposes
for the Upper Susitna River Basin,
Alaska District Corps of Engineers,
Department of the Army, 1975.(_)
2. Electric Power in Alaska 1976-1995
1980
Low Med High
3020 3240 3550
Institute of Social and Economic 2478 3877
Research, University of Alaska, 1976.(_)
3. Alaska Electric Power: An Analysis
of future Requirements and Supply
Alternatives for the Railbelt
Region, Battelle Pacific Northwest
Laboratories, 1978. (_)
4. Upper Susitna River Project Power
Market Analyses, U.S. Department of
Energy, Alaska Power Administration,
1979; South Central Railbelt Area,
Alaska, Upper Susitna River Basin,
Supplemental Feasibility Report,
Corps of Engineers, 1979 (_) and
Phase I Technical Memorandum:
Electric Power Needs Assessment,
South Central Alaska \~ater
Resources Committee, 1979 (_)
2600 3400
2920 3155 3410
1990
Low Med High
5470 6480 8540
5415 12706
8500 10800
4550 6110 8200
1995 2000 2025
Low Med High Low Med High Low Med High
6656 8688 12576 8100 11650 18520
8092 20984
10341 17552 16000 -22500
5672 8175 11778 7070 10940 16920 8110 17770 38020
2
Study
Number
2
3
4
NOTES:
Year of
TABLE 5.8 -PERFORMANCE OF PAST PROJECTIONS
RAILBELT ELECTRIC POWER REQUIREMENTS1
Annual Growth Rate of Percent Errar4
Net Energy Between in Forecast
Net Energy (GWh) Forecast Year & 1980 of Growth
Year of Forecast 3 Rate to
Publication Forecast for 1980 Forecast Actual 1980 (%)
1975 1851 3240 11.9 7.3 + 63
1976 2093 2985 9.3 5.9 + 58
1978 2397 3000 11.9 4.8 + 148
1979 2469 3155 27.8 6.5 + 328
(1) Net Energy figures calculated from sales plus 10 percent for losses
(2) Corresponds to Table 5.7.
(3) Assuming 1980 Net Energy consisting of 2390 of sales plus 10 percent losses.
(4) Indicates overestimation.
5-19
TABLE S.9 -FORECAST TOTAL GENERATION AND PEAK LOADS-TOTAL RAILBELT REGION 1
ISER Low (LES-GM)2 ISER Medium (MES-GM) ISER High (HES-GM)
Peak Peak Peak
Generation Load Generation Load Generation Load
Year (GWh) (MW) (GWh) (MW) (GWh) (MW)
1978 3323 606 3323 606 3323 606
1980 3522 643 3522 643 413S 753
198S 4141 7S7 4429 808 5528 99S
1990 4503 824 4922 898 6336 1146
1995 5331 977 6050 1105 8013 1456
2000 6599 1210 7327 1341 9598 17SO
zoos 7188 1319 8471 1551 11843 2158
2010 7822 1435 9838 1800 14730 2683
Ul
' N
0 Percent z. 71 2.73 3.4S 3.46 4.76 4.76
Growth/Yr.
1978-2010
NOTES:
(1) Includes net generation from military and self-supplied industry sources.
Source: Reference ( )
(2) All forecasts assume moderate government expenditure.
Year
1980
1985
1990
1995
2000
2005
2010
Notes:
TABLE 5.10-RAILBELT REGION LOAD AND ENERGY FORECASTS
USED FOR GENERATION PLANNING STUDIES
L 0 A 0 CASE
low Plus load
Management end Low Medium
Conservation
(LES-GL)2 · (MES-GM)3 (LES-GL Adjusted)1
load toea toad
MW GWh factor MW GWh Factor MW GWh Factor
510 2790 62:.5 510 2790 62.4 510 2790 62.4
560 3090 62.8 580 3160 62.4 650 3570 62.6
620 3430 63.2 640 3505 62.4 735 4030 62.6
685 3810 63.5 795 4350 62.3 945 5170 62.5
755 4240 63.8 950 5210 62.3 1175 6430 62 .. 4
835 4690 64.1 1045 5700 62.2 1380 7530 62.3
920 5200 64.4 1140 6220 62.2 1635 8940 62.4
"
High
(HES-GH)4
-Load
MW GWh Factor
510 2790 62 .. 4
695 3860 63.4
920 5090 63.1
1295 7120 62.8
1670 9170 62.6
2285 12540 62 .. 6
2900 15930 62.1
(1) LES-GL: Low economic growth/low government expenditure with load management and conservation.
(2) Low economic growth/low government expenditure. LES-GU
(3) MES-GM: Medium economic growth/moder~te government expenditure.
(4) HES-GH: High economic growth/high gov·ernment expenditure.
5-21
t -::c
3:
(,!) -
(/) w
_J
<!
(/)
>-
t--(.)
0::
t-
fd _,
w
2500 ··~----------~~----------~----------~-
2000 r-----------~~-----------T--~~------~
1500
1000
0 ~------------~----------~------------~ 1965 1970 1975 1980
YEAR
HISTORICAL TOTAL RAILBELT UTILITY SALES
TO FINAL CUSTOMERS
FIGURE 5.1 ~~~~
5-22
18
17
16
15
14
13
12 -:X:
3: I I
(!) -ff}t 0
_J
<(
(/)
9
>-i-
u 8
0::
i-
(.)
7 w
_J
IJ-1
6
5
4
3
2
LEGEND
HES-GH = HIGH ECONOMIC GROWTH t HIGH GOVERNMENT EXPENDITURE
HES-GM = HIGH ECONOMIC GROWTH + MODERATE GOVERNMENT EXPEM:>ITURE
MES-GM = MODERATE ECONOMIC GROWTH + MOC€RATE GOVERNMENT EXPENilTURE
LES-GM : l!JN ECONOMIC GROWTH+ MODERATE GOVERNMENT EXPENDITURE
LES-GL :: LOW ECON~IC GROWTH t LOW GOVERNMENT EXPENDITURE
II
HES -GH I
I
I ,
I ,
I
/ HES-
o~--------._--------~--------~--------~--------_.--------~ 1980 1985 1990 1995 2000 2005 2010
YEAR
FORECAST ALTERNATIVE TOTAL RAlLBELT
UTILITY SALES
5-23
FIGURE 5.JIRI
I
I
-----!lfU'"'i'C _._ __________ o; ______ _, ___________ .....__,.
I
I
!6---------------------------------------------------------------
-::t:.
LEGEND
HES-GH : H1GH ECONOMIC GROWTH + HIGH GOVERNMENT EXPENDITURE
MES-GM = MODERATE ECONOMIC GROWTH t MODERATE GOVERNMENT EXPENDITURE
LES-GL = LOW ECONOMIC GROWTH +LOW GOVERNMENT EXPE~DITURE
LES -GL ADJUSTED = LOW ECONOMIC GROWTH +LOW GOVERNMENT
EXPENDITURE + LOAD MANAGEMENT AND CONSERVATION
I
I
I
I
I
I
I
I
.I
I
I HES-GH
I
I
I
I
I
I
I
I
~ iO~------------------~-------------------+~~--------------~ (!) -z
Q 9
t:i
0:: w z w ·a
(!)
>-._
(3 7 n: ......
(.)
~ 6
l1J / , ,
, " , ,
,
/
/
, ,
~
, , , ,
I
I
0 __________ ._ ________ ~ ________ _. __________________ ~--------~
1980 1985 1990 1995
YEAR
2000 2005 2010
ENERGY FORECASTS USED FOR GENERATION PLANNING STUDIE. S r.;.;j
FIGURE 5.3 •
5-24
LIST OF REFERENCES
(l) Institute of Social and Economic Research, Electric Power Reguirements for
the Railbelt, June, 1980.
(2) Alaska Center for Policy Studies, Energy Alternatives for the Railbelt -
Study of End-Use Structuv·e, Energy Conservation Potential, Alternative
Energy Resources and Related Public Policy Issues, August, 1980.
(3) Energy Probe, An Evaluation of the ISER Electricity Demand Forecast, July,
1980.
5-25
6 .. RAILBELT SYSTEM AND FUTURE POWER GENERATION OPTIONS
6.1 -Introduction
Effective planning of future electric power generation sources to meet the pro-
jected needs of the Railbelt Region must address a number of concerns. Apart
from the obvious goal of planning to meet projected power and energy needs of
the region, careful consideration must be given to the trade-offs which will be
required in satisfying those needs within the constraints of technical feasi-
bility, economic necessity, acceptable environmental impacts and social prefer-
ences •. The hydroelectric potential in the Susitna River Basin is but one of the
available options for meeting future Rai~belt demand.
If constructed, the Susitna Basin development plan would provide a major portion
of the Railbelt Region energy needs well beyond the year 2000. In order to
accurately determine the most economic basin development plan which clearly
defines details such as dam heights, installed generating capacities, reservoir
~perating rules, dam and powerhouse staging concepts, and construction sche-
dules!) it is first necessary to evaluate in economic terms the plan in the con-
text of the entire Railbelt generating system. This requires that economic
analyses be undertaken of expansion alternatives for the total ftailbelt system
containing several different types of generating sources. These sources include
both thermal and hydropower generating facilities capable of satisfying a speci-
fied load forecast. Economic analyses of scenarios containing alterna~ive
Susitna Basin development plans being investigated wou1d then reveal which is
the most economic basin development plan. This process and the comparison of
other factors such as environmental impacts and soci a 1 preferences, essentially
fa11s within the purview of 11 generation planning~~. These studies are discussed
in more detail in Section 8.
This section describes the process of assembling the information necessary to
carry out these systemwide generation planning studies. Included is a dis-
cussion of the existing system characteristics, the planned Anchorage-Fairbanks
intertie, and details of various generating options including hydroelectric and
thermal, a discussion of the implications of the Fuel Use Act {FUA), and a brief
outline of other options such as tidal and geothermal energy generation. Per-
formance and cost information required for the generation planning studies is
presented-for the hydroelectric and thermal generation options but not for the
tidal and geothermal options. Preliminary indications are that these options
are a.s yet not competitive with the more conventional options considered.
Emphasis is placed on currently feasible and economic generating sources. Other
options such as wind, solar and biomass-fired generation are not considered in
this study. An independent study currently being undertaken for the State of
Alaska by Battelle Pacific North!!lest Laboratories addresses all such options.
It should be stressed that the non-Susitna generation options have only been
-dealt with in sufficient detail to develop representative performance. and GOSt
data for inclusion in the alternative Railbelt system generation scenarios. The
primary objective is tq carry out a preliminary assessment of the feasibility of
the selected Susitna Basin development plan by comparing the costs and benefits
of the uwith Susitna scenario" with selt=cted 11 Without Susitna scenarios".
6-1
6.2 -Existing System Characteristics
(a) System Description
The two major load centers of the Railbelt Region are the Anchorage-Cook
Inlet area and the Fairbanks-Tanana Valley area (see Figure 6.1). At
present, these two areas operate independently. The existing transmission
system between Anchorage and Wi 11 ow consists of a network of 115 k V and 138
kV lines with interconnection to Palmer. Fairbanks is primarily served by
a 138 kV line from the 28 MW coal fired plant at Healy. Communities
between Willow and Healy are served by local distribution.
There are currently nine electric utilities (including the Alaska Power
Administration) providing power and energy to the Railbelt system (See
Table 6.1). In order to obtain information on the current (1980) installed
generation capability of these utilities, the following sources were
consulted:
(i) Published Documents
-WCC Report, ''Forecasting Peak Electrical Demand for
Alaska's Railbelt", September, 1980 (1).
-IECO Transmission Report for the Railbelt, 1978 (2).
-U.S. DOE, "Inventory of Power Plants in the u.s.," April
1979 (3).
-Electrical World Directory of Public Utilities 1979 -1980
Edition (4).
-Williams Brothers Engineering Company, 1978 Report on FMUS
and GVEA Systems ( 5). ·
-FERC Form 12A for the following utilities:
-Anchorage Municipal Light & Power Department (AMLPD)
-Chugach Electric Association (CEA)
-Homer Electric Association (HEA)
-Fairbanks Municipal Utility System (FMUS)
(ii) Discussions With:
-Anchorage Municipal Light and Power Department (AMLPD)
-Fairbanks Municipal Utility System (FMUS)
-Copper Valley Electric Association (CVEA)
-Alaska Power Administration (APAd)
Table 6.1 summarizes the information received from these sources. Some
discrepancies are apparent especially with respect to AMLPD and CVEA. The
ACRES column lists the installed capacity data used in the generating
6-2
planning studies described in this report and represents. a resolution of
discrepancies in data collectedo
Table 6.2 includes a detailed listing of units currently operating in the
Railbelt, information on their performance characteristics, and their on-
line and assumed retirement dates.
With the exception of two hydroelectric plants, the total Railbelt install-
ed capacity· of 944 MW as of 1980 consists of fifty-one thermal generation
units fired by oil, gas or coal, as summarized in Table6.3.
(b) Schedule Retirements
In order to establish a retirement policy for the existing generating
units, sever a 1 references were consul ted including the APA draft feasi-
bility study guidelines (6), FERC guidelines, and his"'torical records.
Utilities, particularly those in the Fairbanks area, were also consulted.
Based on the above, the following retirement periods of operation were
adopted for use in this study:
-Large Co a 1-Fi red Stearn Turbines ( > 100 fvtW):
-Small Coal-Fired Steam Turbines (< 100 MW):
-Oil-Fired Gas Turbines:
-Natural Gas-Fired Gas Turbines:
-Diesels:
-Combined Cycle Units:
-Conventional Hydro:
30 years
35 years
20 years
30 years
30 years
30 years
50 years
Table 6.2 lists the retirement dates for each of the current generating
units based on the above retirement policy.
(c) Schedule of Additions
Only two new projects are currently to be committed within the Railbelt
system. The CEA is in the process of adding 60 MW of gas fired combined
cycle capacity in Anchorage .. The plant will be called Beluga No.8. for
study purposes, the p]ant is assumed to· come on-line in January 1982.
The COE is currently in the post-authorization planning phase for the
Bradley Lake hydroelectric project located on the Kenai Peninsula. As
currently envisaged, the project includes 94 MW of installed capacity and
would produce an annual average energy of 420 Gwh. For study purposes, the
project is assumed to come on-line in 1988.
6.3 -Fairbanks -Anchorage Intertie
Engineering studies are currently being undertaken for construction of an inter-
tie between the Anchorage and Fairbanks systems. As presently envisaged, this
connection will involve a 138 kV transmission line between Willow and Healy and
vmuld provide capability for t\"ansferring 50 MW of capacity at any time. It is
scheduled for completion in 1984. Current intertie studies indicate that it is
economic to construct this intertie such that it can be upgraded to the 345 kV
Susitna transmission capability when Watana comes on-line.
6-3
A brief study was undertaken to check the validity of the assumption that a
fully interconnected system should be maintained as the total system capacity
increases over the next 30 years. A simplified analysis was carried out in
which the economics of two alternative all-thermal generating scenarios was
evaluated for the ISER medium load forecast. The first scenario, called the
"intertie scenario", allows for additional transmission to be added as needed,
with increased capacity requirements being met by the most economic generating
units constructed in optimum geographic locations. The second scenario
restricts the intertie to 138 kV and assumes that increased capacity require-
ments will be met by separate developments in the Anchorage and Fairbanks
areas.
Both scenarios incorporate the committed CEA combined cycle 60 MW plant in 1982
and the 94 MW Bradley Lake hydro plant in 1988. After 1992, in either scenario,
additional generating facilities will be required in both Anchorage and Fair-
banks. The preliminary economic comparison was therefore only carried out for
the period 1980 to 1992.
The intertie scenario requires upgrading of the existing 138 kV line to 230 kV
and new 230 kV lines from Anchorage to Willow and from Healy to Fairbanks in
1986. No additional capacity is necessary. The second scenario requires 75 MW
of gas turbine generation to meet the reserve requirements in the Anchorage area
in 1988, and a 100 MW coal-fired unit to supplement the generation capacity in
the Fairbanks region in 1986. The total present worth cost in 1980 dollars of
the second scenario exceeds that of the first by just over $300 million.
The analysis clearly indicates that it is extremely economic to construct and
maintain a fully integrated system. This conclusion is conservative as it does
not incorporate the benefits to be derived for a fully interconnected system in
terms of load sharing and economy energy transfers after the year 1992. The
actual benefit of the interconnected system could be somewhat higher than esti-
mated.
Based on these evaluations, it was concluded that a fully interconnected system
should be assumed for all the generation planning studies outlined in this
report, and that the intertie facilities would be common to all generation
scenarios considered. In the preliminary comparisons of alternative generation
scenarios, the cost of such intertie facilities were also assumed to be common.
However, in final comparisons of a lesser number of preferred alternative
scenarios, appropriate consideration was given to relative intertie costs. The
cost of transmitting energy from a particular generating source to the intercon-
nected system is included in all cases.
6.4 -Hydroelectric Options
Numerous studies of hydroelectric potential in Alaska have been undertaken.
These date as far back as 1947, and were performed by various agencies including
the then Federal Power Commission, the COE, the USBR, the USGS and the State of
Alaska. A significant amount of the identified potential is located in the
Railbelt Region, including several sites in the Susitna River Basin.
As discussed in Section 6.1, feasibility assessment of the selected Susitna
Basin development plan is based on comparisons of future Railbelt power
6-4
generation s·cenarios with and without the project. An obvious 11 Without Susitnau
scenario is one which includes hydroelectric developments outside the Sustina
Basin. The p'lan formulation and selection methodology discussed in Section 1.4
and Appendix A has been applied in the developmen~ of Railbelt generation plans
which include and exclude Susitna. Those plans which involve the Susitna Pro-
ject are discussed in detail in Sections 7 and 8. Those plans which incorporate
hydroeler.tric developments other than Susitna are discussed in this Section ..
(a) Assessment of Hydro Alternatives
The application of the five-step methodology (Figure 1.2) for selection of
non-Susitna plans which incorporate hydroelectric developments, is present-
ed in detail in Appendix C,. This process is summarized in this section and
Figure 6.2. Step 1 of this process essentially established the overall ob-
jective of the exercise as the selection of an optimum Railbelt generation
plan which incorporated the proposed non-Susitna hydroelectric develop-
ments, for comparison with other plans.
Under Step 2 of the selection process, all feasible candidate sites were
identified for inclusion in the subsequent screening exercise. A total of
91 potential sites {Figure 6.3) were obtained from inventories of potential
sites published in the COE National Hydropower Study (7) and the APAd
report 11 Hydroelectric Alternatives for the Alaska Railbelt 11 (8} ..
(b) Screening of Candidate Sites
The screening of sites required a total of four successive iterations to
reduce the number of alternatives to a manageable short list. The overall
objective of this process was defined as the selection of approximately 10
sites for consideration in plan-formul?cion~ essentially on the basis of
published data on the sites and appropriately defined criteria. The first
iteration in this process was based on a coarse screen in which sites which
were considered technically infeasible or not economically viable were re-
jected. For this purpose, economic viability for a site was defined as
energy production costs 1 ess than 50 mi 11 s per k~~h, based on economic para-
meters. This value was considered to be a reasonable upper limit consis-
tent with Susitna Basin alternatives (See Section 8}.
Energy production costs were derived for each site considered, using the
capital cost data published in the cited reports, updated to 1980 levels,
and using published cost escalation data and an appropriate contingency
allowance. As discussed in Section 8, annual costs were derived on the
basis of a 3 percent cost of money, net of general inflation. Allowances
for operation and maintenance costs were also included in these estimates.
For this initial screening process, the reported energy yield data for each
site were then used as a basis for estimating annual energy production
costs in mills per kWh.
As a result of this screen, 26 sites were reject.ed and the remaining 6b
sites were subjected to a second iter·ation of screening. The additional
criteria established for this screening were environmental in nature.
Based on data published in the COE and APAd reports, (7, 8) rejection of
sites occurred if:
6-5
(i) They would cause significant impacts within the boundaries of an
existing National Park or a proclaimed National ~lonument area;
(ii) They were located on a river in which:
-anadromous fish are known to exist;
-the annual passage of fish at the site exceeds 50,000;
- a confluence with a tributary occurs, upstream of the site, in which
a major spawning or fishing area is located.
As a result of this screen, 19 sites were rejected and the rema1n1ng 46
sites were subjected to a third iteration of economic and environmental
screening. At this stage in the se 1 ect ion process, adjustments were made
to capital and energy production costs for each site to take account of
transmission line costs to link each site to the Anchorage-Fairbanks inter-
tie. A representative list of 28 sites was thus derived by judgemental
elimination of the more obviously uneconomic or less environmentally accep-
table sites. These sites were then categorized into sizes as follows:
-less than 25 MW: 5 sites
-25 MW to 100 MW: 15 sites
-greater than 100 MW: 8 sites
The fourth and fi na 1 screen was then performed in which a more deta i 1 ed
numerical environmental assessment was made. Eight evaluation criteria
were utili zed:
-Impact on big game
-Impact on agri cul tura 1 potentia 1
-Impact on waterfowl, raptors and endangered species
-Impact on anadromous fish
-Restricted land uses
-Impact on wi 1 derness areas
-Impact on cultural, recreational and scientific resources
-Impact generated by access
The above environmental ranking criteria 11ere assigned numerical v1eights,
and scale ratings for each site and each criterion were developed using
available data. Total scores were then calculated for each site by summing
the products of the weight and scale ratings.
This process allowed the number of sites to be reduced to the ten sites
listed in Table 6.3.
(c) Plan Formulation and Evaluation
In Step 4 of the plan selection process, the ten sites shortlisted under
Step 3 were further refined as a basis for formulation of Railbelt genera-
tion plans. Engineering sketch-type layouts were produced for each of the
sites, and quantities and capital costs were evaluated. These costs are
also listed in Table 6.3 and incorporate a 20 percent al1011ance for contin-
gencies and 10 percent for engineering and owner's administration. A total
of five plans were formulated incorporating various combinations of these
sites as input to the Step 5 evaluations.
6-6
Power and energy values for each of the developments were re-evaluated 1n
Step 5 utilizing monthly streamflow and a computer reservoir simulation
model. Details of these calculations are given in Appendix F and the
results are summarized in Table 6.3.
The essential objective of Step 5 was established as the derivation of the
optimum plan for the future Railbelt generation incorporating non-Susitna
hydro generation as well as required thermal generation. ·rhe methodology
used in evaluation of alternative generation scenarios for the Railbelt are
discussed in detail in Section 8, The criteria on which the preferred plan
was finally selected in these activities was least present worth cost based
on economic parameters established in Section 8.
The selected potential non-Susitna Basin hydro developments (Table 6.3)
were ranked in terms of their economic cost of energy. They were then
introduced into the all thermal generating scenario during the planning
analyses (See Section 6.5), in groups of two or three. The most economic
schemes were introduced f/irst and were followed by the less economic
schemes.
The results of these analyses are summarized in Table 6.4 and illustrate
that a minimum total system cost of $7040 million can be achieved by the
introduction of the Chakachamna~ Keetna, and Snow proje.cts (See a 1 so Figure
6.4).
Additiona) sites such as Strandline, Allison Creek and Talkeetna-2 can also
be introduced without significantly changing the economics, and would be
beneficial in terms of displacing non-renewable energy resource consump-
tion.
6.5 -Thermal Options
As discussed earlier in this Section, the major porti·on of generating capability
in the Railbelt is currently thermal, principally natural gas with some coal and
oil-fired installations. There is no doubt that the future electric energy de-
mand in the Railbelt would technically be satisfied by an all-thermal generation
mix. In the following paragraphs an outline is presented of studies undertaken
to determine an appropriate all-thermal generation scenario for comparison with
other scenarios in Section 8. A more detailed description of these studies may
be found in Appendix B of this report.
(a) Assessment of Thermal Alternatives
The plan formulation and selection methodology discussed in Section 1 .. 4 and
Appendix A, has been adopted in a modified form to develop the necessary
all-thermal generation plans (see Figure 6.5). The overall objective
established in Step 1 is the selection of an optimum all-thermal Railbelt
generation plan for comparison with other plans.
In Step 2 of the selection process, consideration was given to gas, coa 1
and oi 1-fi red generation sources only, from the standpoint of techni ca 1 and
economic feasibility alone. The broader perspectives of other alternative
6-7
resources and the relevant environmental, social and other issues involved
are being addressed in the Battelle alternatives study.
This being the case, the Step 3 screening process was therefore considered
unnecessary in this study and emphasis was placed on selection of unit
sizes appropriate for inclusion in the generation planning exercise. Thus
for study purposes, the following five types of thermal power generation
units were considered:
-Coal-fired steam
-Gas-fired combined-cycle
-Gas-fired gas turbine
-Diesel
To formulate plans incorporating these alternatives it was necessary to
develop capital cost and fuel cost data for these units and other related
operational characteristics.
(b) Coal-Fired Steam
Aside from the military power plant at Fort Wainwright and the self-
supplied generation at the University of Alaska, there are currently two
coal-fired steam plants in operation in the Railbelt (see Table 6.1).
These plants are small in comparison with new units under consideration in
the Lower 48 and in Alaska.
(i) Capital Costs
Based on the general magnitude of the Railbelt load requirements,
three coal-fired unit sizes were chosen for potential capacity addi-
tions: 100, 250 and 500 M\j. All new coal units are estimated to have
an average heat rate of 10,500 Btu/kWh, and involve an average con-
struction period of five to six years. Capital costs and operating
parameters are defined for coal and other thermal generating plants on
Table 6.5. These costs include a 16 percent contingency, a 10 percent
allowance for construction facilities and utilities and 12 percent for
engineering and owner's administration. The costs 11ere developed
using published data for the Lower 48 (9) and appropriate Alaska
scaling factors based on studies conducted by Battelle (10). It is
unlikely that a 500 MW plant will be proposed in the Fairbanks region
because forecasted demand there is insufficient to justify placing
this much capacity on line at one time. Therefore, costs for such a
plant at Fairbanks are not included.
To satisfy the national New Performance Standards (11), the capital
costs incorporate provision for installation of flue gas desulfuriza-
tion for sulphur control, highly efficient combustion technology for
control of nitrogen acids and baghouses for particulate removal.
6-8
(ii) Fuel Costs
The total estimated coal reserves ~n Alaska are shown on Table 6.6.
Projected opportunity costs for Alaskan coal range from $1.00 to $1.33
per million Btuo A cost of $1.15 was selected as the base coal cost
for generation planning (see Table 6.7). The market price for coal is
currently within the same general cost range as the indicated oppor-
tunity cost.. ·
Real growth rates in coal costs (excluding general price inflation)
ar~ based on fuel escalation rates developed by the Department of
Energy (DOE) (12) in the mid-term Energy Forecasting System for DOE
Region 10 which includes the states of Alaska~ Washington, Oregon and
Idaho. Specified price escalation rates pertaining to the industrial
sector was selected to reflect the bulk purchasing advantage of
utilities more accurately than equivalent rates pertaining to the
commercial and residential sectors. A composite annual escalation
rate of 2.93 percent has been computed for the period 1980 to 1995
from the five yearly values given by the DOE. This composite rate has
been assumed to apply to the 1995-2005 period as suggested by the DOE.
Beyond 2005, zero real growth in the conl price is assumed.
(iii) Other Performance Characteristics
Annual operation and maintenance costs and ~epresentative forced out-
age rates are shown on Table 6. 5.
(c) gombined Cycle
A combined cycle plant is one in which electricity is generated partly in a
gas turbine and partly in a steam turbine cycle. Combined cycle plants
achieve higher efficiencies than conventional gas turbines. There are two
combined cycle plants in Alaska at present. One is operational and the
other ts under construction (See Table 6.1). The plant under construction
is the B.eluga #9 unit owned by Chugach Electric Association (CEA). It .will
add a 60 MW steam turbine to the system sometime in 1982.
(i} Capital Costs
A new combined cycle plant unit size of 250 MW capacity was considered
to be representative of future additions to generating capability in
the Anchorage area. This is based on economic sizing for plants in
the Lower 48 and projected load increases in the Railbelt. A heat
rate of 8500 Btu/kWh was adopted based on technical publications
issued by the Electric Power Research Institute (13).
The capital cost was estimated using the same basis and data sources
as for the coal-fired steam plants and is listed in Table 6.5.
6-9
(i i) Fuel Costs
The combined cycle facilities would burn only gas with the opportunity
value ranging from $1.08 to $2.92 per million Btu. A gas cost of
$2.00 was chosen to reflect the equitable value of gas in Anchorage,
assuming development of the export market. Currently, the local
incremental gas market price is about half of this amount due to the
relatively light local demands and limited facilities for export.
Using an approach similar to that used for coal costs, a real annual
growth rate in gas costs of 3.98 percent was obtained from the DOE
studies for 1980 to 2005. Zero percent was assumed thereafter.
(iii) Other Performance Characteristics
Annual operation and maintenance costs and a representative forced
outage rate are given in Table 6.5.
(d) Gas-Turbine
Gas turbines are by far the main source of thermal power generating re-
sources in the Railbelt area at present. There are 470 MW of installed gas
turbines operating on natural gas in the Anchorage area and approximately
168 MW of oil-fired gas turbines supplying the Fairbanks area. (See Table
6.1). Their low initial cost, simplicity of construction and operation,
and relatively short implementation lead time have made them attractive as
a Railbelt generating alternative. The extremely low cost contract gas in
the Anchorage area also has made this type of generating facility cost-
effective for the Anchorage load center.
(i) Capital Costs
A unit size of 75 MW was considered to be representative of a modern
gas turbine plant addition in the Railbelt region. Ho1~ever, the
possibility of installing gas turbine units at Beluga was not con-
sidered, since the Beluga development is at this time primarily being
considered for coal.
Gas turbine plants can be built over a two-year construction period
and have an average heat rate of approximately 12,000 Btu/kWh. The
capital cost was evaluated using the same data source as for the coal-
fired plants and incorporates a 10 percent allowance for construction
facilities and 14 percent for engineering and ovmer's administration.
This cost includes provision for wet control of air emissions.
(ii) Fuel Costs
Gas turbine units can be operated on oil as \~ell as natural gas. The
opportunity value and market cost for oil are considered to be equal,
at $4.00 per million Btu. Real annual grov1th rates in oil costs were
developed as described above and amounted to 3.58 percent for the
1980-2005 period and zero percent thereafter.
6-10
(iii) Other Performance Characteristics
Annual operation and maintenance costs and forced outage rates are
shown in Table 6.5.
(e) Diesel Power Generation
Most diesel plants in the Railbelt today are on standby status or are oper-
ated only for peak load service. Nearly all the continuous duty units were
retir·ed in the past several years due to high fuel prices. About 65 MW of
diesel plant capacity is currently available.
{i) Capital Costs
The high cost of diesel fuel and low capital cost makes new diesel
plants most effective for emergency use or in remote areas where small
loads exist. A unit size of 10 MW was selected as appropriate for-
this type of facility. The capital cost was derived from the same
source as given in Table 6.5 and includes provision for a fuel injec-
tion system to minimize air pollution.
{ii) Fuel Costs
Diesel fuel costs and growth rates are the same as oil costs for gas
turbines.
(iii) Other Performance Characteristics
Annual operation and maintenance and the forced outage rate is given
i n Tab 1 e 6 . 5,
(f) Plan Formulation and Evaluation
The six candidate unit types and sizes developed under Step 2 were used to
formulate plans for meeting future Railbelt power generation requirements
in Step 4. The objective of this exercise was defined as the formulation
of appropriate plans for meeting the project Railbelt demand on the basis
of economic preferences~
Two different cases of natural gas consumption policy v1ere considered in
formulating plans. The first, called the "renewal" policy allo\'Jed for the
renewal of natural gas turbines at the end of their economic lives, antici-
pating the possible exemptions that utilities may obtain from the FUA. The
second policy, called the 11 no renewals" policy assumed that the utilities
would not be allowed to reconstruct plants as they are retired and that
they would only be allowed to construct new plants with not more than 1500
hours of annual operation (see Condition 9 of the FUA as discussed in
Section 6.6).
6-11
In the subsequent Step 5 evaluation of the two basic plans, the OGP5 gener-
ation planning model was utilized to develop a least cost scenario incor-
porating the necessary coal, oil, and gas fired generating units. The
results for the very low, low, medium, and high load forecasts are summar-
ized in Table 6. 4. They indicate that for the medi urn forecast the total
system present worth cost is slightly higher than $8,100 million.
As illustrated by the results displayed in Table 6.4, these two policies
have very similar economic impacts. The difference in present worth costs
for the medium forecast amounts to only $20 million. For purposes of this
study, therefore 9 it is assumed that the "no renewals 11 policy is more
appropriate and is used to be representative of the all thermal generation
scenario.
Figure 6.6 illustrates this all thermal generating scenario graphica11y.
6.6 -Impact of the Fuel Use Act
(a) Ba.ck_ground
Th:? uPow•cr Plant and Industrial Fuel Use Act of 1978 11 (FUA), Public La\v
9~-620~ regulates the use of natural gas and petroleum to reduce imports
and conserve scarce non-renewable resources. It is, therefore~ essential
to understand the implications of this act and to incorporate important
aspects in the generation planning studies.
Section 201 of the FUA prohibits the use of petroleum or natural gas as a
primary energy source in any new electric power plant and precludes the
construction of any new power plant without the capability to use an alter-
nate fuel as a primary energy source. There are, however, twelve differ-
ent exemption categories incorporated in the Act. Plants which can be
included in any of these categories may qualify for a permanent exemption.
These exemption catagories are:
(1)
(2)
(3)
(4)
(5)
(6)
( 7)
{8)
(9)
(10)
(11)
(12)
Cogeneration
Fuel mixture
Emergency purposes
Maintenance of reliability of service (short development lead time)
Inability to obtain adequate capital
State or local requirements
Inability to comply with applicable environmental requirements
Site limitations
Peak load power plants
Intermediate load power plants
Lack of alternative fuel supply for the first ten years of useful
life
Lack of alternative fuel supply at a cost which does not substan-
tially exceed the cost of using imported petroleum.
6-12
·(b) FUA and the Railbelt
The two Anchorage utilities, Chugach Electric Association (CEA) and Anchor-
age Muni ci pa 1 Light and Power Department (AMLPD) have been ab 1 e to maintain
relatively low electric rates to their customers by the use of natural gas
from the Cook inlet region. ~s repQrted to the DOE in June of 1980, CEA
paid an average of $0.32/Million Btu (MMBtu) for gas, with its cheape~t
contract supplying its largest plant with gas at $0.24/MMBtu. Compared to
the U.S. average price of over $2.00/MMBtu, this situation represents an
obvious incentive for the continued use of natural gas for electric genera-
tion by CEA. AMLPD reports that its cost for gas is approximately
$1.00/MMBtu, which is still below the national average utility price. The
price differences exist because CEA holds certain long term contracts at
favorab 1 e rates.
In spite of the low gas prices currently enjoyed in Anchorage, it is
assumed that the cost of natural gas will rise rapidly as soon as suitable
export facilities now under consideration are developed. Thus, the "oppor-
tunity11 cost of $2.00/MMBtu discussed earlier is considered appropriate for
future system comparisons and relevent to the discussion on the FUA
pre!'."cnted here.
It can also be argued that the Cook Inlet reserves are sufficiently large
and the cost of delivery to potential markets in the Lower 48 is 1ow enough
to make export to these states feasible.
Assuming that new gas-fired generation would be either a gas turbine or
gas-fired boiler located in the Anchorage area, there would be no parti,-
cular capital or time planning constraints and the unit would be actively
used to meet the anticipated load. Under these assumptions, the exemption
categories 1 through 5 would not apply.
Categories 6 and 7 require the existence of some state, local or environ-
mental requirement which would preclude the development of the plant using
an alternative fuel,. As no such constraint is foreseen, it is 1 ike ly that
these categories would apply.
To obtain an exemption under category 8~ it must be shown that alternative
fue 1 s are inaccessible due to physi ca 1 1 i mi tati ons, and that transporta-
tion, handling and storage, and waste disposal facilities are unavailable
or other physi ca 1 1 imitations exist. It is not anticipated that generation
facilities, including coal, are inaccessible and is therefore not likely
that this category would apply.
To qualify for exemption 9 for peak load power, a petitioner must certify
ti~at the plant will be operated solely as a peak load plant. In addition,
the EPA or appropriate state administrator must also certify that alternat-
ive fuel use (other than natural gas) will contribute to concentration of a
pollutant wh1eh would exceed a national air quality standard. However, due
to the shift in concern regarding the use of gas as compared to oil, this
reqairement appears to be liberally interpreted. If this certification
could be obtained, any plant would still be limited in output to only 1500
hours of generation per year at design capacity.
6-13
Exemption 10 for intermediate load power plants is available only when
petroleum ·is used as the primary energy source. This exemption category
waul d therefore not apply"
To obtain exemption 11, the petitioner must demonstrate an effort has been
made to obtain an adequate and reliable supply of an alternate fuel and
show that such a supply will not be available for 10 years of the useful
plant life. The petitioner must also prove that the earliest possible
online date for the alternative is not soon enough to prevent reserve capa-
city margins becoming unacceptably low. It is not anticipated that exemp-
tions would be granted under. this category.
Exemption 12 requires that the alternative source is at least 30 percent
more costly than similar plant operating on imported oil before an exemp-
tion is granted. The actual cost of natural gas does not directly enter
into the decision. Results of the studies outlined in this report indicate
that there are coal-fired and hydro alternatives which can produce energy
at prices well below that associated with imported oil. It is, therefore,
. also unlikely that this exemption is applicable.
{c) Conclusions
The Anchorage utilities are subject to the prohibitions of the FUA for the
development of ne\'1 sources of power generation. Existing facilities may
continue to use gas, but the use of gas in new facilities will apparently
be restricted to peak load applications only.
6.7 -Other Options
The more exotic types of electric utility generating stations, such as wind 2
biomass, solar, tidal and geothermal are being investigated for application to
the Railbelt in the Battelle alternatives study. These could provide a portion
of the Railbelt's generating needs in a conjunction with a thermal or thermal/
hydroelectric generation plan. It is recognized that these options could be
incorporated into the generation plan, however a cursory review of the two of
these resources which are most likely to be developed {geothermal and tidal)
would indicate that their contribution would be ancillary to the principal
alternatives described in the previous sections.
(a) Geotherma 1
Of the numerous geothermal sites identified in the state, only a few are
located in the South Central Region encompassing the Railbelt (14). Of
these, all but one are low temperature sources (100-ZOO~F) and therefore
feasible only for building or process heating. The high temperature
Klawasi site, located east of Glennallen, has been recently investigated
for electric power generation potential (14). Although a study has been
made for the development of this site, it has not been funded. No
potential consumer for the energy has been identified, mainly because it is
remoteness from any existing or planned major transmission connection from
the site vicinity to populated areas to the south or \'lest. As suggested by
this study, this type of energy would possibly be feasible if the Alaska
pipeline corridor becomes populated since the geothermal site is near the
route of the line.
6-14
Based upon available data, a potential site capacity on the order of
several hundred MW may exist, although only a 25 MW development is
discussed. Unless a transmission loop paralleling Alaska Highway Routes 2
and 4 or 1 is constructed, the· likelihood of a geothermal development at
this location economically supplying any of the Railbelt needs is remote.
Geothermal sources have therefore not been considered further in this
study.
(b) Tidal Power
The Cook Inlet area has long been recognized as having some of the highest
tidal ranges )n the world, with mean tides ranges of more than 30 feet at
Sunrise, on Turnagain Arm, 26 feet at Anchorage, and decreasing towards the
lower reaches of Cook Inlet to 15 feet or so near Seldovia. Initial
studies of Cook Inlet tidal power development {15) have concluded that
generation from tide fluctuation is technically feasible and numerous
conceptual schemes ranging in estimated capacity of 50 MW to 25,900 MW have
been developed. Preliminary studies indicate that the tidal power would
require some type of retiming of energy production to be useful in the
Railbelt electrical system. The earliest estimate of on-line data for a
tidal plant would be the mid 1990's.
Studies are currently underway to develop more specific information on how
much and \'lhich portion of the Railbelt energy needs this type of generation
could supply and what the cost would be. This information is not available
for consideration in this phase of the generation planning studies.
6-15
Abbreviations
AMLPO
CEA
GVEA
FMUS
CVEA
MEA
HEA
SES
APAd
TOTAL
Table 6.1 -TOTAL GENERATING CAPACITY WITHIN THE RAILBELT SYSTEM
Railbelt Utility
Name
Anchorage Municipal Light & Power
Department
Chugsch Electric Association
Golden Valley Electric Association
Fairbanks Municipal Utility System
Copper Valley Electric Association
Matanuska Electric Association
Homer Electric Association
Seward Electric System
Alaska Power Administration
6-16
Installed Capacitt {MW)
WCC( ) !£Co( J oOt( ) ELt .. wo. ( ) ACRES
1980-1978 -1979 1979 -1980
184.0
420o0
211.0
67 .o
18.0
0.9
2.6
5.5
909.0
130.5
411 .. 0
218.6
65.5
0.6
9;,2
5.5
30.0
870 .. 9
148.0
402.2
230.0
68.2
13.0
3.0
1.7
5.5
30.0
901.6
108.9
410.9
211.0
67.4
0.9
3.5
5.5
30.0
838.0
215.4
411.0
211.0
67 .1;. ..,
0.9
2.6
5.5
30.0
943.6
Table 6.2 -GENERATING UNITS WITHIN THE RAILBELT -1980
Railbelt S£a£10n On1£ On1t Installation Heat Rate Installed M1n1mum Maximum Fuel Retirement
Utility Name R Type Year (BTU/kWH) Capacity Capacity Capacity Type Year
(MW) (MW) (MW)
Anchorage AMLPD 1 GT 1962 15,000 14 2 15 NG 1992
Municipal AMLPD 2 GT 1964 15,000 14 2 15 NG 1994
Light & Power AMLPD 3 GT 1968 14,000 15 2 20 NG 1998
Department AMLPD 4 GT 1972 12,000 28.5 2 35 NG 2002
(AMLPD) G.M. Sullivan 5,6,7 cc 1979 8,500 140.9 NA NA NG 2009
Chugach Beluga 1 GT 1969 13,742 15.1 NA NA NG 1998
Electric Beluga 2 GT 1968 13,742 15.1 NA NA NG 1998
Association Beluga 3 GT 1973 13,742 53.5 NA NA NG 2003
(CEA) Beluga 4 GT 1976 13,742 9.3 NA NA NG 2006
Beluga 5 GT 1975 13,742 53.5 NA NA NG 2005
Beluga 6 GT 1976 13,742 67.8 NA NA NG 2006
Beluga 7 GT 1978 13,742 67.8 NA NA NG 2008
Bernice Lake 1 GT 1963 23,440 8.2 NA NA NG 1993
2 GT 1972 23,440 19.6 NA NA NG 2002
3 GT 1978 23,440 24.0 NA NA NG 2008
0"\ International
39,9731 I Station 1 GT 1965 14.5 NA NA NG 1995 .... 2 GT 1975 14.5 NA NA NG 1995 .._, 39,9731
3 GT 1971 39,973 18.6 NA NA NG 2001
Knik Arm 1 GT 1952 28,264 14.5 NA NA NG 1985
Copper Lake 1 HY 1961 15.0 NA NA 2011
Golden Valley Healy 1 ST 1967 11,808 25.0 7 27 Coal 2002
Electric 2 IC 1967 14,000 2.7 2 3 Oil 1997
Association North Pole 2 GT 1976 13,500 64.0 5 64 Oil 1996
(GVEA) 2 GT 1977 13,000 64.0 25 64 Oil 1997
Zehander 1 GT 1971 14,500 17.65 10 20 Oil 1991
2 GT 1972 14,500 17.65 10 20 Oil 1992
3 GT 1975 14,900 2.5 1 3 Oil 1995
4 GT 1975 14,900 2.5 1 3 Oil 1995
5 IC 1970 14,000 2.5 1 3 Oil 2000
6 IC 1970 14,000 2.5 1 3 Oil 2000
7 IC 1970 14,000 2.5 1 3 Oil 2000
8 IC 1970 14,000 2.5 1 3 Oil 2000
9 IC 1970 14,000 2.5 1 3 Oil 2000
10 IC 1970 14,000 2.5 1 y Oil 2000
Table 6.2 (Continued)
RaJ.lbelt Station On1t Ontf lnstallat 10n Heat Rate Installed Mtn1mum Max1mum Fuel Ref1rement
Utility Name # Type Year (BTU/kWH) Capacity
(MW)
Capacity
(MW)
Capacity
(MW)
Type Year
Fairbanks Chen a 1 ST 1954 14,000 5.0 2 5 Coal 1989
Municipal 2 ST 1952 14,000 2.5 1 2 Coal 1987
Utiltiy 3 ST 1952 14,000 1. 5 1 1. 5 Coal 1987
System (FMUS) 4 GT 1963 16,500 7.0 2 7 Oil 1993
5 ST 1970 14,500 20.0 5 20 Coal 2005
6 GT 1976 12,490 23.1 10 29 Oil 2006
FMUS 1 IC 1967 11,000 2.7 1 3 Oil 1997
2 IC 1968 11,000 2.7 1 3 Oil 1998
3 IC 1968 11 '000 2.7 1 3 Oil 1998
Homer Elec. Homer=
Association Kenai 1 IC 1979 15,000 0.9 NA NA Oil 2009
(HEA) Pt. Graham 1 IC 1971 15,000 0.2 NA NA Oil 2001
Seldovia 1 IC 1952 15,000 0.3 NA NA Oil 1982
2 IC 1964 15,000 0.6 NA NA Oil 1994
3 IC 1970 15,000 0.6 NA NA Oil 2000
0>
I Matanuska Talkeetna IC 1967 15,000 0.9 NA NA Oil 1997 ......
00 Elec. Assoc.
(MEA)
Seward SES IC 1965 15,000 1. 5 NA NA Oil 1995
Electric
System (SES) 2 IC 1965 15,000 1.5 NA NA Oil 1995
Alaska Eklutna HY 1955 30.0 NA NA 2005
Power
Administration
(APAd)
TOTAL 943.6
Notes:
GT = Gas turbine
CC = Combined cycle
HY = Conventional hydro
IC = Internal Combustion
ST = Steam turbine
NG = Natural gas
NA = Not available
( 1 ) This value judged to be unrealistic for large range planning and therefore is adjusted
to 15,000 for generation planning studies.
Table 6.3-OPERATING AND·ECONOMIC PARAMETERS FOR SELECTED HYDROELECTRIC PLANTS
Max. Average
Gross Installed Annual Plant Capit'l
Head Capacity En err Factor Cos~ No. Site. River Ft. (MW) (Gwh (%) ($10 )
1 Snow Snow 690 50 220 50 255
2 Bruskasna Nenana 235 30 140 53 238
3 Keetna Talkeetna 330 100 395 45 463
4 Cache Talkeetna 310 50 220 51 564
5 Browne Nenana 195 100 410 47 625
6 Talkeetna-2 Talkeetna 350 50 215 50 500
7 Hicks Matanuska 275 60 245 46 529
8 Dlakachamna Chakachatna 945 500 1925 44 1480
9 Allison Allison Creek 1270 8 33 47 54
10 Strandline
Lake Beluga 810 20 85 49 126
NOTES:
(1) Including engineering and owner's administrative costs but excluding AFDC.
(2) Including AFDC, Insurance, Amortization, and Operation and Maintenance Costs.
6-19
Economic2
Cost af
Energy
($/1000 Kwh)
45
113
73
100
5!1
90
8~
30
12!\
115
Table 6.4-RESULTS OF ECONOMIC ANALYSES OF ALTERNATIVE GENERATION SCENARIOS
Installed Capac1Ey (MW) by Iota! System lofal System
Category in 2010 Installed Present Worth
Generation Scenario 0GP5 Run ~Fiermai ~aro Capacity in Cost -
lype bescr1p£1on Load Fa recast Id. No. cal Gas 011 2010 (MW) ($106)
All Thermal No Renewals Very Low 1 LBT7 500 426 90 144 1160 4930
No Renewals Low L7E1 700 300 40 144 13B5 5920
With Renewals Low L2C7 600 657 30 144 1431 5910
No Renewals Medium LME1 900 B01 50 144 1B95 B130
With Renewals Medium LME3 900 B07 40 144 1B91 B110
No Renewals High L7F7 2000 1176 50 144 3370 13520
With Renewals High L2E9 2000 576 130 144 3306 13630
No Renewals Probabilistic LOF3 1100 1176 100 144 3120 B320
Thermal Plus No Renewals Plus: tied ilHTl L7W1 600 576 70 744 1990 70BO
Alternative Chakachamna (500)2-1993
Hydro Keetna (100)-1997
No Renewals Plus: Medium LFL7 700 501 10 B94 2005 7040
Chakachamna (500)-1993
Keetna (100)-1997
Snow (50)-2002
0"1 No Renewals Plus: Medium LWP7 500 576 60 B22 195B 7064 I
N Chakachamna (500)-1993
0 Keetna (100)-1996
Strandline (20),
Allison Creek (8),
Snow (50)-199B
No Renewals Plus: Medium LXF1 700 426 30 B22 197B 7041
Chakachamna (500)-1993
Keetna (100)-1996
Strandline (20),
Allison Creek (B),
Snow (50) -2002
No Renewals Plus: Mediun L403 500 576 30 922 2028 7088
Chakachamna (500)-1993
Keetna (100)-1996
Snow (50), Cache (50),
Allison Creek (B),
Talkeetna-2 (50),
Strandline (20)-2002
Notes:
(1) Incorporating load management and conservation
(2) Installed capacity
Table 6.5 -SUMMARY OF THERMAL GENERATING RESOURCE PLANT PARAMETERS
PLANT TYPE
coAL-FIRED STEAM COMBINED GAs
Parameter CYCLE TURBINE DIESEL
500 MW 250 MW 100 MW 250 MW 75 MW 10 MW
Heat Rate (Btu/kWh) 10,500 10,500 10,500 8,500 12,000 11,500
O&M Costs
Fixed O&M ($/yr/kW) 0.50 1.05 1.30 2.75 2.75 0.50
Variable O&M ($/MWH) 1.40 1.80 2.20 0.30 0.30 5.00
Outages
Planned Outages (%) 11 11 11 14 11 1
Forced Outages (%) 5 5 5 6 3.8 5
Construction Period (yrs) 6 6 5 3 2
0'1 Start-up Time (yrs) 6 6 6 4 4
I
N .... Total Ca~ital Cost
($ mll 1on)
Railbelt: 175 26 7.7
Beluga: 1,130 630 290
Unit Ca~ital Cost ($/kW) 1
Railbelt: 728 250 778
Belu a: 2473 2744 3102
Notes:
(1) Including AFDC at 0 percent escalation and 3 percent interest.
Table 6.4-RESULTS OF ECONOMIC ANALYSES OF ALTERNATIVE GENERATION SCENARIOS
Installed Capac1Ey (MW) by Iota! System Iota! System
Cat egor:t in 2010 Installed Present Worth
Generation Scenario OGPS Run ~liermai Hyaro Capacity in Cost -
iype Oeser 1pt 1on Load Forecast Id. No. cal Gas 011 2010 (MW) ($106)
All Thermal No Renewals Very Low 1 LBT7 500 426 90 144 1160 4930
No Renewals Low L7E1 700 300 40 144 1385 5920
With Renewals Low LZC7 600 657 30 144 1431 5910
No Renewals Medium LME1 900 801 50 144 1895 8130
With Renewals Medium LME3 900 807 40 144 1891 8110
No Renewals High L7F7 2000 1176 50 144 3370 13520
With Renewals High LZE9 2000 576 130 144 3306 13630
No Renewals Probabilistic LOF3 1100 1176 100 144 3120 8320
Thermal Plus No Renewals Plus: Medium L7W1 600 576 70 744 1990 7080
Alternative Chakachamna (500)2-1993
Hydro Keetna (100)-1997
No Renewals Plus: Medium LFL7 700 501 10 894 zoos 7040
Chakachamna (500)-1993
Keetna (100)-1997
Snow (50)-2002
"' No Renewals Plus: Medium LWP7 500 576 60 822 1958 7064 I
N Chakachamna (500)-1993
0 Keetna (100)-1996
Strandline (20),
Allison Creek (8),
Snow (50)-1998
No Renewals Plus: Medium LXF1 700 426 30 822 1978 7041
Chakachamna (500)-1993
Keetna (100)-1996
Strandline (20),
Allison Creek ( 8),
Snow (50)-2002
No Renewals Plus: Medium L403 500 576 30 922 2028 7088
Chakachamna (500)-1993
Keetna (100)-1996
Snow (SO), Cache (SO),
Allison Creek (8),
Talkeetna-2 (SO),
Strandline (20)-2002
Notes:
(1) Incorporating load management and conservation
(Z} Installed capacity
Table 6.5 -SUMMARY OF THERMAL GENERATING RESOURCE PLANT PARAMETERS
PLANT TYPE
~OAC-FIR~B SI~AM CDMBIN~D GAS
Parameter CYCLE TURBINE DIESEL
500 MW 250 MW 100 MW 250 MW 75 MW 10 MW
Heat Rate (Btu/kWh) 10,500 10,500 10,500 8,500 12,000 11,500
O&M Costs
Fixed O&M ($/yr/kW) 0.50 1.05 1.30 2.75 2.75 0.50
Variable O&M ($/MWH) 1.40 1.80 2.20 0.30 0.30 5.00
Outages
Planned Outages (%) 11 11 11 14 11 1
Forced Outages (%) 5 5 5 6 3.8 5
Construction Period (yrs) 6 6 5 3 2
en Start-up Time (yrs) 6 6 6 4 4
I
N ,_, Total carital Cost
($ m1l 1on)
Railbelt: 175 26 7.7
Beluga: 1' 130 630 290
Unit Caeital Cost ($/kW) 1
Railbelt: 728 250 778
Belu a: 2473 2744 3102
Notes:
(1) Including AFDC at 0 percent escalation and 3 percent interest.
Table 6.6 -ALASKAN FUEL RESERVES
ea 1ng
Approximate Value
Reserve Field Reserve Btu/lb
Coal (million tons) Buluga 2400 7200 -8900
Nenana 2000 7500 -9400
Kenai 300 6500 -8500
Matanuska 100 10300 -14000
Gas (billion cubic feet) North Slope 29000 plus
Cook Inlet 4200 plus
Oil (billion cubic feet) North Slope 8400 plus
Cook Inlet 200
Table 6.7 -FUEL COSTS ANO ESCALATION RATES SELECTED FOR
GENERATION PLANNING STUDIES
ue ype
Parameter Natural Gas Coal 011
Economic Cost -$/Million BTU 2.00 1.15 4.00
Annual Escalation Rate -%
Per1od: 1980 -2005 3.98 2.93 3.58
2006 -2010 0 0 0
6-22
LOCATION MAP
LEGEND
\I PROPOSED
DAM SITES
--_,-PROPOSED 1:36 Kl/ Ll NE
-um• EXISTING LINES
LOCATION MAP FIGURE
1m
t
N
~
SITE
SELECTION
PREVIOUS
STUDIES
ENGENEERING
LAYOUTS AND
COST STUDIES
PLAN
CRITERIA
DATA ON OIFFE~NT
THERMAL GENERATING
SOURCES
COMPUTER MODELS TO
EVALUAi"E
-POWER AND
ENERGY YIELDS
-SYSTEM WIDE
ECONOMICS
ECONOMICS
ENVIRONMENTAL
OBJECTIVE
ECONOMICS
CRITERIA
ECONOMICS
4 ITERATIONS
SNOW { S} -CH, K CH, K,S a THERMAL
BRUSKASNA (B) -CH, K 1 S LEGEND
KEETNA ( K) -CH 1 K.S,SL,AC
CACHE ( CA) -CH, K,S,SL,AC I\
BROWNE ( BR) -CH, K, S ,SL,AC 1 CA, T-2 -u4\ STE':P NUMBER
TALKEETNA-2 (T-2) fN STANDARD
HICKS ( H) PROCESS
CHAKACHAMNA ( C H ) {APPENDIX A)
ALLiSON CREEK ( AC)
STRANDLINE LAKE ( SL)
FORMULATION OF PLANS INCORPORATING NON-SUSITNA HYDRO GENERATION . IIIII
FIGURE 6~2 .[8
I :!>f.~ EQl.iAI..S A?PROXIMA.i!::lY 40 MILES
& G 0
o-25 MW 25·100 MW :> 100~
•• STRANDLINE L. 13 • WHISKERS 26. SNOW 39. LANE
, 2. LOWER BELUGA 14, COAL 27. KENAI LOWER 40. TOKICHITNA
3. LOWER LAKE CR. 15. CHULITNA 28. GERSTLE 4L, YENTNA
4. ALLISON CR, !6. OHIO 29 .. TANANA R. 42. CATHE~AL .BLUFFS
5. CRESCENT LAKE 2 17. LOWER CHULITNA w. BRUSKASNA 43.. JOHNSON
s. GRANT LAKE 18. CACHE 31 .. KANTISHNA R. 44 .• aRO\'me
J
7, McCLURE BAY 19. GREENSTONE 32. UPPER BEW.GA 45. JUNCTlON IS.
a. UPPER NELLIE . JUAN 20. TALKEETNA 2 33. COFFEE 4G. 'JAct'.oN lS
9. POWER CREEK 21. GRANITE GORGE ~. GULKANA R. 47. TAZILNA
10. SILVER LAKE 22. KEETNA 35. KLUTINA 48. KENAl LAKE
n. SOL(}MON GULCH 23. SHEEP CREEK 36. BRADLEY LAKE 49. CHAKACHAM~iA
12. TUSTUMENA 24. SKWENTNA 37. HICK'S SITE
25, TALAC~lUUTNA 38, LOWE
FM;ORE &31•1 SELECTED ALTERNATIVE HYDROELECTRIC SITES
;='
~2
0
0
I
>-
}-
(.)
~I
<3:
(.)
10
8
.:I:
~6
0
0
0
I
>-
(.!)
~4 z w
2
715
1980
PEAK
LOAD
LEGEND
1990
D HYDROELECTRIC
t~fi~j~)i~!j!~J COAL FIRED THERMAL
E:Zl GAS FIRED THERMAL
2000
OIL FIRED THERMAL( NOT SHOWN ON ENERGY DIAGRAM
NOTE : RESULTS OBTAINED FROM
· OGPS RUN LFL 7
TOTAL DISPATCHED
ENERGY
CHAKACHAMNA
EXISTING AND COMMITTED
198.0 1990 2000·
TIME
1954
2010
2010 .
GENERATION SCENARIO INCORPORATING THERMAL ! .. Bill .. I AND ALTERNATIVE HYDROPOWER DEVELOPMEf"TS
-MEDIUM LOAD FORECAST~ FIGURE 6.4
6-26
l
)
PREVIO~S .
STUDIES
'-~
UNIT TYPE
SELECTION
COAL : 100 MW
250 MW
500 MW
COMBINED CYCLE: 250 MW
GAS TURBINE : 75 MW
DIESEL : 10 MW
PLAN
FORMULATION
OBJECTIVE
ECONOMIC
COMPUTER MODELS
TO EVALUATE
SYSTEM WIDE ECONOMICS
EVALUATION
OBJECTIVE
GAS RENEWALS
NO GAS RENEWALS
ECONOMIC
NO GAS RENEWALS
LEGEND
FO.RMULATlON OF PLANS INCORPORATING ALL-THERMAL GENERATION
STEP NUMBER IN
STANDARD PROCESS
(APPENDIX A)
FIGURE 6.51 BIR I
>-1-
(.)
~· <t
(.)
10
8
:t:
3=6 (!)
0
0
0
>-(!)
715
1980 1990
LEGEND:
D HYDROELECTRIC
M~%~i~i~~~lJ COAL FIRED THERMAL
I2:ZJ GAS FIRED THERMAL
2000
OIL FIRED THERMAL ( NOT SHOWN ON ENERGY DIAGRAM)
NOTE : RESULTS OBTAINED FROM
OGPS RUN LMEI
1895
2010
ffi 4 TOTAL DISPATCHED
z ENERGY
w
2
EXISTING AND COMMITTED
0------------------------------------------------------------------~ 1980 1990 2000 2010
TIME
ALL THERMAL GENERATION SC.ENARIO [i]
-MEDIUM LOAD FORECAST-··~~~
FIGURE 6.6 ftl [I
6-28
LIST OF REFERENCES
(1)
(2)
(3)
(4)
{5)
(6)
(7)
(8)
(9)
Woodward-Clyde Consultants~ Forecasting Peak Electrical Demand for Alaska's
Railbelt, September, 1980.
IECO, Transmission Report for the Railbelt, 1978.
U.S. Department of Energy, Inventory of Power Plants in the u.s., April,
1979. .
Electrical World, Directory of Public Utilities, 1979-1980, 87th Edition ..
Williams Brothers Engineering Company, Repo"rt on Fairbanks Municipal
Utility .System and Golden Valley Electric Association, 1978.
Alaska Power Authority, Plan of Study fot Project Feasibility and FERC
License Application, Volume I, 1979.
U.S. Army Corps of Engineers, National Hydropower Study, July, 1979.
Alaska Power Administration, Hydroelectric Alternatives for the Alaska
Railbelt, February, 1980.
Electric Power Research Institute, Coal-Fired Power Plant Capital Cost
Estimates-EPRI AF-342 (SOA 77-402), Final Report~ December, 1977.
{10) Battelle Pacific Northwest Laboratory, Alaskan Electric Power -An Analysis
of Future Requirements and Supply Alternatives for the Railbelt Region,
March, 1978.
(11) The Bureau of National Affairs {BNA), BNA Policy and Practice Series: ~ir
Pollution Control, Section 101; Ambient Air Quality Standards, Section 111;
State Policies, Section 121, New Source Performance Standards, 1980.
{12) U.S. Department of Energy, Office of Conservation and Solar Energy, Federal
Energy Management and Planning Programs; Methodology and Proceduf-~S for
Life Cycle Cost Analyses -Average Fuel Costs, Federal Register, December,
1980.
{13) Electric Power Research Institute, Combined C cle Power Plant Capital Cost
Estimates -EPRI AF-610 (SOA 77-402 , Final Report, December, 1977.
(14) Markle, D., Geothermal Energy in Alaska~ Geo-Heat Utilization Center,
Apri 1, 1979.-
(15) Acres American Incorporated, Preliminary Assessment of Cook Inlet Tidal
Power -Phase 1, Prepared for the State of Alaska, September, 1981.
(I
6-29
I
I
7 -SUSITNA BASIN
7.1 -Introduction
The purpose of this section is to describe climatological, physical and environ-
mental characteristics of the Susitna River Basin and to briefly acquaint the
reader with some of the ongoing studies being undertaken to augment previously
recorded data. It deals with general descriptions of the climatology, hydrology
and geology, and seismic· considerations and outlines the environmental aspects ..
The information presented has been obtained both from previous studies and the
fi£Hd progra'Tis and office studies initiated during 1980 under Tasks 3, 4, 5 and
7.
7.2 -Climatology and Hydrology
The climate of the Susitna Basin upstream from Talkeetna is generally charac ....
terized by cold, dry winters and warm, moderately moist summers. The upper
basin is dominated by continental climatic conditions while the lower basin
falls within a zone of transition between maritime and continental climatic
influences~
(a) Climatic Data Records
Data on precipitation, temperature and other climatic parameters have been
co 11 ected by NOAA at several stations in the south central region of
Alaska since 1941. Prior to the current studies, there were no stations
located within the Susitna basin upstream from Talkeetna. The closest
stations where long-term climate data is available are at Talkeetna to the
south and Summit to the north. A summary of the precipitation and tempera-
ture data available in the vicinity of the basin is presented in Table
7.1.
Six automatic climate stations were established in the upper basin during
1980 (see Figure 7.1). The data currently being collected at these
stations includes air temperature, average wind speed, wind direction, peak
wind gust, relative humidity, precipitation, and solar radiation. Snowfall
amounts are being measured in a heated precipitation bucket at t_he Watana
station. Data are recorded at thirty minute intervals at the Sus·itna
Glacier station and at fifteen minute intervals at all other statiot~s.
(b) Precipitation
Precipitation in the basin varies from low to moderate amounts in the lower
elevations to heavy in the mountains. Mean annual precipitation of over 80
inches is estimated to occur at elevations above 3000 feet in the Talkee.tna
Mountains ~nd the Alaskan Range whereas at Talkeetna station, at elev~tion
345 feet, the average annual precipitation recorded is about 28 inches.
The average precipitation reduces in a northerly direction as the conti-
nental climate starts to predominate. At Summit station, at elevation 2397
feet, the average annual precipitation is only 18 inches. The seasonal
distribution of precipitation is similar for all the stations in and ·
surrounding the basin. At Talkeetna, records show that 68 percent of the
total precipitation occurs durjng the warmer months, May through October,
7-1
while only 32 percent is recorded in the winter months. Average recorded
snowfall at Talkeetn~ is about 106 inches. Generally, snowfall is re-
stricted to the monthl of October through April with some 82 percent
snowf a 11 recorded i n t)'e period November to March.
The U.S. Soi 1 Conservation ~e,"vice (SCS) operates a network of snow course
stations in the basin and records of snow depths and water content are
available .as far back as 1964. The stations within the Upper Susitna Basin
are generally located at elevations below 3000 feet and indicate that
annual snow accumulations are around 20 to 40 inches and that peak depths
occur in late March. There are no historical data for the higher eleva-
tions.. The basic network was expanded during 1980 with the addition of
three new sno\'1 courses on the Susi tna g1 aci er (see Figure 7 .1). Art"'ange-
ments have been made with SCS for continuing the collection of information
from the expanded network during the study period.
. (c) Temperature
Typical temperatures observed from historical records at the Talkeetna and
Summit stations are presented in Table 7 .2. It is expected that the
temperatures at the dam sites will be somewhere between the values observed
at these stations.
(d) ·River Ice
(e)
The Susitna River usually starts to freeze up by late October. River ice
conditions such as thickness and strength vary according to the river
channel shape and slope, and more importantly, with river discharge.
Periodic measurements of ice thickness at several locations in the river
have been carried out during the winters of 1961 through 1972. The maximum
thicknesses observed at selected locations on the river are given in Table
7.3. Ice breakup in the river commences by late April or early May and ice
jams occasionally occur at river constrictions resulting in rises in water
level of up to 20 feet.
Detailed field data collection programs and studies are underway to iden-
tify potential problem areas should the Susitna Project be undertaken, and
to develop appropriate mitigation measures. The program includes compre-
hensive aeri a 1 and ground reconnaissance and documentation of freeze-up and
break-up processes. This data will be used to calibrate computer models
which can be used to predict the ice cover regime under post project
conditions. It will then be possible to evaluate the impacts of
anticipated changes in ice conditions caused by the .project and any
proposed mitig~tion measures.
Water Resources .
Streamflow data has been recorded by the USGS for a number of years at a
total of 12 gaging stations on the Susitna River and its tributaries (see
Figure 7.1). The length of these records varies from 30 years at Gold
Creek to about five years at the Susitna station. There are no historical
records of streamflow at any of the proposed dam sites. For current study
7-2
purposes, available streamflow records have been extended to cover the full
30 year period using a multisite correlation technique to fill the gaps in
flow data at each of the stations. Flow sequences at the dam sites have
subsequently been generated for the same 30 year period by extrapolation on
the basis of dra.i nage basin areas.
A gaging station was established at the Watana dam site in June 1980 and
continuous river stage data is beirJ collected. It is proposed to develop
a rating curve at the station with streamflow measurements taken during the
1980 and 1981 seasons. River flows will be calculated and used to check
the extrapolated streamflow data at the Watana site.
Seasonal variation of flows is extreme and ranges from very low values in
winter (October to Apri 1) to high summer values (May to September). For
the Susi tna River at Go 1 d Creek the average winter and summer flows are
2100 and 20,250 cfs respectively, i.e. a 1 to 10 ratio. The monthly
average flows in the Susitna River at Gold Creek are gi\ven in Figjre 7.3".
On average, approximately 88 percent of the streamflow recorded at Gold
Creek station occurs during the summer months. At higher elevations in the
basin the distribution of flows is concentrated even more in the summer
months. For the Maclaren River near Paxson (El 4520 ft) the average winter
and summer flows are 144 and 2100 cfs respectively, i~e. a 1 to 15 ratio.
The monthly percent of annual discharge and mean monthly discharges for the
Susitna River at the gaging stations are given in Table 7.4.
The Susi tna River above the confluence with the Chu 1 i tna River contributes
only approximately 20 percent of the mean annua~ flow measured near Cook
Inlet (at Susitna station). Figure 7.2 shows how the mean annual flow of
the Susitna increases towards the mouth of the river at Cook Inlet.
(f) Floods
The most common causes of flood peaks in the Susitna River Basin are snow-
melt or a combination of snoltATlelt and rainfall over a large area. Annual
maximum peak discharges generally occur between May and October with the
majority, approximately 60 percent, occurring in June. Some of the annual
maximum flood peaks have also occurred in August or later and are the
result of heavy rains over large areas augmented by significant snowmelt
from higher elevations and glacial runoff.
A regional flood frequency analysis has been carried out using the recorded
floods in the Susitna River and its principle tributaries, as well as the
Copper, Matanuska and Tosina Rivers. These analyses have been conducted
for two different time periods within the year. The first period selected
is the open water period, i.e. after the ice breakup and before freezeup ..
This period contains the largest floods which must be accommodated by the
project. The second period represents that portion of time during which
ice conditions occut in the river. These floods, although smaller, can be
accompanied by ice jamming, and must be considered during the construction
phase of the project in planning and design of coffer dams for river
diversion.
The results of these frequency analyses will be used for estimating floods
in ungaged rivers and streams. They \'li 11 a 1 so be used to check the
accuracy of the Gold Creek Station rating curve which is important in
7-3
determining spillway design floods for the proposed Susitna River projects.
Multiple regression equations have been developed using physiographic
parameters of the basin such as catchment area, stream length, mean annual
precipitation, etc. to assess flood peaks at the dam sites and inter-
mediate points of interest in the river. Table 7.5 lists mean annual, 100
and 10,000 year flood peaks as well as the 50 year flood peaks under water
and under ice cover conditions. These latter flood peaks are included as
they are representative of the flood conditions for which the construction
diversion facilities must be designed.
Estimates of the probable maximum floods in the Susitna Basin were made by
COE in their 1975 study (PMF). A river basin computer simulation model
(SSARR) was used for that purpose. A detailed review of the input data to
the model has been undertaken and discussions held with COE engineers to
improve understanding of the model parameters used. A series of computer
runs with the model have been undertaken to study the effects of likely
changes in the timing and magnitude of three important parameters, i.e.
probable maximum precipitation, snow pack and temperature. These studies
have indicated that the PMF is extremely sensitive to certain of these
parameters and that additional refinement of the flood estimation technique
is warranted.
(g) River Sediment
Periodic suspended sediment samples have been collected by the USGS at the
four gaging stations upstream from Gold Creek (see Figure 7.1) for varying
periods between 1952 and 1979. Except for three samples collected at
Denali in 1958, no bed load sampling has been undertaken at any stations.
Data coverage during high-flow, high sediment events is poor and conse-
quently any estimate of total annual sediment yield has a high degree of
uncertainty.
The most comprehensive analysis of sediment load in the river to date is
that undertaken by the COE in 1975. Table 7.6 gives the COE estimates of
sediment transport at the gaging stations.
7.3 -Regional Geology
The regional geology of the area in which the Susitna Basin is located has been
extensively studied and documented (1, 2). The Upper Susitna Basin lies within
what is geologically called the Talkeetna Mountains area. This area is
geologically complex and has a history of at least three periods of major
tectonic deformation. The oldest rocks (250 to 300 m.y.b.p.)* exposed in the
region are volcanic flows and limestones which are overlain by sandstones and
shales dated approximately 150 to 200 m.y.b.p. A tectonic event approximately
135 to 180 m.y.b.p. resulted in the instrusion of large diorite and granite
plutons, which caused intense thermal metamorphism. This was followed by marine
deposition of silts and clays. The argillites and phyllites which predominate
at Devil Canyon were formed from the silts and clays during faulting and folding
of the Talkeetna Mountains area in the Late Cretaceous
*m.y.b.p.: million years before present
7-4
(\
period (65 to 100 m.y.b.p~). As a result of this faulting and uplift, the
eastern portion of the area was elevated, and the oldest volcanics and sediments
were thrust over the younger metamorphics and sediments. The major area of
deformation during this period of activity was southeast of Devil Canyon and
included the Watana area. The Talkeetna Thrust Fault. a well-known tectonic
feature which has been identified in the literature (note wee report), trends
northwest through this region. This fault was one of the major mechanisms of
this overthrusting from southeast to northwest. The Devi1 Canyon area was
probably deformed and subjected to tectonic stress during the san1e peri ad, but
no major deformations are evident at the site {Figure 7.4).
The diorite pluton that forms the bedrock of the Watana site was intruded into
sediments and volcanics about 65 m.y.b.p. The andesite and basalt flows near
the site may have been formed immediately after this plutonic intrusion, or
after a period of er-osion and minor deposition.
During the Tertiary period (20 to 40 m.y.b.p.} the area surrounding the sites
was again uplifted by as much as 3,000 feet. Since then widespread erosion has
removed much of ·the older sedimentary and volcanic rocks. During the last
several million years at least two alpine glaciations have carved the Talkeetna
Mountains into the ridges, peaks, and broad glacial plateaus seen today.
Post-glacial uplift has induced downcutting of streams and rivers, resulting in
the 500 to 700 feet deep V-shaped canyons that are evident today, particularly
at the Vee and Devil Canyon dam sites. This erosion is believed to be still
occurring and virtually all streams and rivers in the region are considered to
be actively downcutting. This continuing erosion has removed much of the
glacial debris at higher elevations but very little alluvial deposition has
occurred. The resulting landscape consists of barren bedrock mountains, glacial
till covered plains~ and exposed bedrock cliffs in canyons and along streams.
The arctic climate has retarded development of topsoil.
Further geologic mapping of the project area and geotechnical investigation of
the proposed dam sites was i ni ti ated under the current study in 1980, and wi 11
continue through early 1982.
7.4-Seismic Aspects
Relatively little detailed investigation of the seismology of the Susitna Basin
area had been undertaken prior to the current studies. A comprehensive program
of field work and investigation of seismicity was initiated in 1980.
The.seismic studies referred to in the following sections were specifically
aimed at developing design criteria for the Devil Canyon and Watana dam sites.
However~ much of the discussion is pertinent to all dam sites in the Susitna
Basin and is therefore included in this section.
(a) Seismic Geology
The Talkeetna Mountains region of south-central Alaska lies within the
Talkeetna Terrain. This term is the designation given to the immediate
region of south-central Alaska that includes the upper Susitna River basin
(as shown on Figure 7.4). The region is bounded on the north by the Denali
Fault, and on the west by the Alaska Peninsula features that make up the
Central Alaska Range. South of the Talkeetna Mou,ntains, the Talkeetna
Terrain is separated from the Chugach Mountains by the Castle Mountain
7-5
'· ··.
Fault. The proposed Sus1tna Hydroelectric Project dam sites are located in
the We$'~t::rn half of the Talkeetna Terrain. The eastern half of the region
includes the relatively inactive, ancient zone of.sediments under the
Copper River Basin and is bounded on the east by the Totschunda sectio11 of
the Denali Fault and the volcanic Wrangell Mountains.
Regional earthquake activity in the project area is closely related to the
plate te<;tonics of Alaska. The Pacific Plate is underthrusting the North
American Plate in this region. The major earthquakes of Alaska, including
the Good Friday earthquake of 1964, have primarily occurred along the
boundary between these plates.
The historical seismicity in the vicinity of the dam sites is associated
with crustal earthquakes within the North American Plate and the shallow
and deep earthquakes generated within the Benjoff Zone, which underlies the
project area. Historical data reveals that the major source of earthquakes
in the site region is in the deep portion of the Benioff Zone, with depths
ranging between 24 to 36 miles below the surface. Several moderate size
earthquakes have been reported to have been generated at these depths. The
crustal seismicity within the Talkeetna Terrain is very low based on
historical records. Most of the recorded earthquakes in the area are
reported to be related to the Denali-Toschunda Fault, the Castle Mountain
Fault or the Benioff Zone. ·
{b) Field Investigations
For project design purposes, it is important to identify the surface
expressions of potent-ial seismic activity. Within the Talkeetna Terrain,
numerous 1 ineaments and features were investigated as part of the 1980
seismic studies. Utilizing available air photos, satellite imagery and
airborne remote sensing data, a catalog of reported and observable discon-
tinuities and linear features (lineaments) was compiled. After elimination
of those features that were judged to have been caused by glaciation,
bedding, river processes, or-man's impact, the 216 remaining features were
screened. The 48 significant features passing the screen were then classi-
fied as either being features that could positively be identified as
faults, or features which could possibly be faults but for which a
definitive origin could not be identified.
The following criteria were used in the screening process:
-All lineaments or faults that have been subjected to recent displacement
are retained for further study.
-All lineaments located within 6 miles of project structures, or having a
branch that is suspected of passing through a structure is retained for
further study unless there is evidence that they have not experienced
displacement in the last 100,000 years.
-All features identified as faults which have experienced movement in the
last 100,000 years are retained. ~
These guidelines were formulated after review of regulatory requirements of
the WPRS, COE, U.S. Nuclear Regulatory Commission, Federal Energy
Regulatory Commission, and several state regulations.
7-6
Of the 48 candidate features, only 13 features were judged to be signifi-
cant for the design of the project. These 13 features include four fea-
tures at the Watana site ( i ncl udi ng the Talkeetna Fault and the Susi tna
feature) and nine features at the Devi 1 Canyon site. It is worth noting
that no evidence of a surface expression was observed in the vicinity of
the so-called Susitna feature during the 1980 studies. These thirteen
features will be further investigated during 1981 to establish their
potential impact on the project design.
{c) Microseismic Monitoring
To support the identification of potential faults in the project area, a
short-term microseismic mon·itoring network was installed and operated for
three months. The objective of this exercise was to collect microearth-
quake data as a' basis for studying the types of faulting and stress orien-
tation within the crust, the correlation of microearthquakes with surface
faults and lineaments, and seismic wave propagation characteristics. A
total of 265 earthquakes with sensitivity approaching magnitude zero were
recorded. Of these events, 170 were recorded at shallow depths, the
largest being magnitude 2.8 (Richter Scale). Ninety-eight events were
related to the Benioff Zone, the 1 argest being magnitude 3. 7. None of the
microearthquakes recorded at shallow depths were found to be related to any
surface feature or 1 i neament within the Ta 1 keetn a Terrain, including the
Talkeetna Fault. The depth of the Benioff Zone was? distinctly defined by
this data as being 36 miles below the Devil Canyon site and 39 miles below
the Watana site.
(d) Reservoir Induced Sei smi ci tx
The subject of Reservoir Induced Seismicity (RIS) was studied for the pro-
posed project area on a preliminary basis using worldwide RIS data and site
specific information. The phenomenon of RIS has been observed at numerous
large reservoirs where seismic tremors under or immediately adjacent to the
reservoir have been corre 1 ated to periods of high fi 1 ii ng rate. In recent
years, this subject has drawn considerable attention within the engineering
and seismic community. It is thought that RIS may be caused by the in-
creased weight of the water in the reservoir or by increased pore pressures
migrating through and .11 1ubricating 11 joints in the rock and acting hydrauli-
cally upon highly stressed rock. Studies indicate that for a reservoir
system to trigger a significant earthquake, a pre-existing fault with
recent displacement must be under or very neal~ to the reservoir. The
presence of a fault with recent displacement has not been confirmed at
either site.
The analysis of previously reported cases indicated a high probability of
RIS for the proposed Susitna reservior on the basis of its depth and
volume, if faults with recent displacement exist nearby. Most RIS recorded
events are believed to be due to an e.arly release of stored energy in a
fault. Thus~ in serving as a mechanism for energy release, the resultant
earthquakes are likely to be smaller than if full energy buildup had
occurred. In no case studied has an RIS event exceeded the estimated
maximum credible earthquake on a related fault. Therefore, RIS of itself
7-7
will not control the design earthquake determination and is considered only
for purposes of estimating recurrence intervals of potential events.
(e) Preliminary Ground Motion Evaluations
On the basis of the geologic and seismic studies, three main sources of
potential earthquakes have been identified at this time. These sources are
the Denali Fault located roughly 40 miles north of the sites, Castle
Mountain Fault less than 60 miles south of the sites and the Benioff Zone
30 to 36 miles below the su·rface. No evidence has yet been found to
indicate that any of the features and lineaments identified to date could
be regarded as surface expressions of faults that have experienced dis-
placement during recent geologic times. Thus, for current study purposes~
no attempt is made to assign potential earthquake magnitudes to the 13
features identified ·as warranting further study. Further field studies
will be conducted on these features during 1981 to ensure that eliminating
them from consideration is justified.
For preliminary project design puroses, very conservativ~ assumptions have
been made for anticipated ground motions which would be caused by possible
earthquakes occurring on the three faults. The Denali Fault has been
assigned a preliminat~y conservative maximum credible earthquake value of
magnitude 8. 5. This earthquake, when attenuated to the sites~ is postu ..
lated to generate a mean peak acceleration of 0.21g at both the Watana and
Devil Canyon sites. The Castle Mountain Fault has been assigned a preli-
minary conservative value of magnitude 7.4, which would generate a mean
peak acceleration in the 0 .. 05g to 0. 06g range at the sites. The Benioff
Zone has been assigned an upper bound conservative value of ma~nitude 8. 5,
which would generate a mean peak acceleration of 0. 41g at the 14atana site
and 0.37g at the Devil Canyon site. ·The duration of potential strong
motion earthquakes for both the Denali and Benioff Zones is conservatively
estimated to be 45 seconds. It is evident that of these three potential
sources, the Benioff Zone will govern the design. Further studies will be
undertaken to finalize these maximum credible earthquake magnitudes and to
further evaluate the features identified within the Talkeetna Terrain.
There is every indication that further study will lead to a reduction in
the design earthquake magnitudes for the three known faults. Due to their
distant locations, none of these faults have any potential for causing
ground rupture at the sites.
Numerous large dams have been designed to accommodate ground motions from
relatively large earthquakes located close to the dam. In California, darns
are routinely designed to withstand ground motions from magnitude 7.5 to
8.5 earthquakes at distancesr,of 12 miles. Dams have also been designed to
accommodate up to 20 feet of horizontal displacement and three feet of
vertical displacement. All of these conditions are more severe than those
anticipated at the Susitna sites. Oroville Dam in central California was
designed to withstand severe seismic loadings and has been progressively
analyzed as new data and methods become available.. Current evaluations
indicate that the dam, which is comparable in size to Watana, could with-
stand seismic loadings comparable to those postulated for the Watana and
Devil Canyon sites.
7-8
7.5 -Environmental Aspects
Numerous studies of the envi ronrnental characteristics of the Susi tna River Basin
have been undertaken in the past. The current studies were initiated in early
1980 and are planned to continue indefinitely. These studies constitute the
most comprehensive and detailed exm~ination of the Susitna Basin ever under-
taken, and possibly of any comparable resource. In this section, descriptions
of ambient biological and vegetation conditions are presented. These
descriptions are based on reviews of the literature as well as the preliminary
results of on-going studies.
(a) Biological
{ i ) Fi sheri es
The Susitna basin is inhabited by resident and anadromous fish. The
anadromous group includes five species of Pacific salmon: sockeye
(red); coho (silver); chinook (king); pink (humpback); and chum (dog)
salmon. Dolly Varden are also present in the lower Susitna Basin with
both resident and anadromous populations. Anadromous smelt are known
to run up the Susi tna River as far as the Deshka River about 40 miles
fr'om Cook In 1 et.
Salmon are known to migrate up the Susitna River to spawn in tributary
streams. Surveys to date indicate that salmon are unable to migrate
through Devil Canyon into the Upper Susitna River Basin. To varying
degrees spawning is also known to occur in freshwater sloughs and side
channels. For a number of years in the past, distribution data has
been collected for the lower Susitna River and tributaries. As part
of the ongoing studies, additional resource and population information
is being collected.
Principal resident fish in the basin include grayling, rainbow trout,
lake trout, whitefish, sucker, sculpin, burbot and Dolly Varden.
Si nee the Susi tna is a gl aci a 1 fed str~am the waters are silt 1 aden
during the summer months. This tends to restrict sport fishing to
clearwater tributaries and to areas in the Susitna near the mouth of
these tributaries.
In the Upper Susitna Basin grayling populations occur at the mouths
and in the upper sections of clear water tributaries. Between Devil
Canyon and the Oshetna Rivers most tributaries are too steep to
support significant fish populations. Many terrace and upland lakes
in the area support lake trout and grayling populations.
(i i) Big Game
The project area is known to support spet.i es of caribou, moose, bear,
wolves, wolverine and Da11 sheep.
-Caribou: The Nelchina caribou herd which occupies a range ·of about
20,000 square miles in southcentral Alaska has been important to
7-9
hunters because of its size and proximity to population centers.
The herd has been studied continuously since 1948. The population
dec 1 ined from a high of about 71, 000 in 1962 to a low of between
6,500 and 8,100 animals in 1972. From October 1980 estimates, the
Nelchina caribou herd contained approximately 18,500 animals
composed of 49 percent cows, 30 percent bulls and 21 percent calves.
During the late winter of 1980, the caribou were distributed in the
Chistochina-Gakona River drainages, the western foothills of the
Alphabet Hills and the Lake Louise Flat. There were two main migra-
tion routes to the northern foothills of the Talkeetna Mountains ...
The first route was across the Lake Louise Flat to the calving area
via the lower Oshetna River, and the second was across the Susitna
River in the area from Deadman Creek to the 11 big bend 11 of the
Susitna. Calving occurred between the Oshetna River and Kosina
Creek between the 3,000 to 4,500 feet elevations. The main surrmer-
ing concentration of caribou occurred in the northern and eastern
slopes of the Talkeetna ~1ountains between Tsisi Creek and Crooked
Creek, primarily between 4,000 and 6,000 feet, Most caribou were
located on the Lake louise Flat during the rut. During early winter
the herd was sp·l it in two groups. One group was located in the
Slide Mountain-little Nelchina River area and the other was spread
from the Chistochina River west to the Gakona River through the
Alphabet Hills to the Maclaren River.
It appears that at least two small subherds with separate calving
areas also existed, one in the upper Talkeetna River, and one in the
upper Nenana-Susitna drainages.
The proposed impoundments would inundate a very small portion of
apparent low quality caribou habitat. Concern has been expressed
that the impoundments and associated development might serve as
barriers to caribou movement, increase mortality, decrease use of
nearby areas and tend to isolate subherds.
/-Moose: Moose are distributed throughout the Upper Susitna Basin.
Population estimates for November 1980 in census areas 6, 7 and 14
(Fig. 7.5) were approximately 830 and 3,000 respectively. Winter
distributions are shol'm on Figure 7 .5.
Studies to date suggest that the areas to be inundated are utilized
by moose primarily during the winter and spring. The loss of their
habitat could reduce the moose population for the area. The areas
do not appear to be important for calving or breeding purposes, how-
ever they do provide a winter range that could be critical during
severe winters. In addition to direct losses, displaced moose could
create a lower capacity for the. animals in surrounding areas.
-Bear: Black bear and brown bear populations in the vicinity of the
proposed reservoirs appear to be healthy and productive. Brown
bears are ubiquitous throughout the study area while black bears
appear largely confined to a finger of forested habitat along the
Susitna River.
7-10
The proposed impoundments are 1 ikely to have 1 i ttl e impact on the
availability of adequate brown bear den sites, however the extent
and utility of habitats utilized in the spring following emergence
from the dens may be reduced. The number of brown bears in the
3,500 square mile study area is approximately 70.
Black bear distribution appears to be largely confined to or near
the for·ests found in the vicinity of the Susitna River and the major
tributarieso Utilization of the forest habitat appears most
preva 1 ent in the early spri ngo In the 1 ate summer b 1 ack bears tend
to mo\re into the more open shrublands adjacent to the spruce forest
due to the greater prevalence of berries in these areas.
Most vf the known active dens in the Devil Canyon area will not be
inundated although several known dens wi.ll be inundated by the
Watana Resevoir.
-Wolf: Five known and four to five suspected wolf packs have been
identified in the Upper Susitna Basin (Fig. 7.6) (3). Territory
sizes for the five studied wolf packs averaged 452 to 821 square
miles. Known wolf territories are eventually non-overlapping during
any particular year. A minimum of 40 wo 1 ves were known to inhabit
the study area in the spring of 1980. By fall the packs had
increased to an estimated 77 wolves.
Impacts on wolves could occur indirectly due to reduction in prey
density, particularly moose. Temporary increases could occur in the
project area due to displacement of prey from the impoundment areas.
Direct inundation of den and rendezvous sites may decrease wolf den-
sities. Potential for increased hunting and trapping pressure could
also act to increase wolf mortality.
-Wolverine: Wolverines occur throughout the study area a 1 though they
show a preference towards upland shrub habitats on southerly and
westerly slopes. Potential impacts would relate to direct loss of
habitat, construction disturbance and increased competition for
prey.
-Dall SheeQ: Da11 sheep are known to occupy all portions of the
Upper Susitna River Basin which contains extensive areas of habitat
above 4,000 feet elevation. Three such areas in the proximity of
the project area include the Portage-Tsusena Creek drainages, the
Watana Creek Hills and Mount Watana.
Since Dall sheep are usually found at elevations above 3,000 feet,
impacts will likely b~ ~estricted to potential indirect disturbance
from construction activities and access.
(iii) Furbearers
Furbearers in the Upper Susitna Basin include red fox, coyote, lynx,
mink, pine marten, river otter, short-tailed weasels least weasel,
muskrat and beaver. Direct innundation, construction activities and
access can be expected to generally have minimal imp·act on th~se
species.
7-11
(iv} Birds and Non-Game Mammals
One hundred and fifteen species of birds were recorded in the study
area during the 1980 field season, the mn.:;t abundant being Scaup and
Common Redpo 11.~ Ten a-ctive raptor/raven nests have been recorded and
of these~ two Bald Eagle nests and at least four Golden Eagle nests
would be flootied by the proposed reservoirs, as would about three
currently inactive raptor/raven nest sites. Preliminary observations
indicate a lo'll popul~iton of waterbirds on the lakes in the region;
however, Trumpeter" Swans nested on a number of 1 akes between the
Oshetna and Tyone Rivers~
Flooding would destroy a large percentage of the riparian cliff
habitat and forest habitats upriver of Devil Canyon dam. Raptors and
ravens using the cliffs could be expected to find alternate nesting
sites in the surrounding mountains, and the forest inhabitants are
relatively common breeders in forests in adjacent regions. Lesser
amounts of lowland meadows and of fluviatile shorelines and alluvia,
each important to a few species, will also be lost. None of the
waterbodi es that appear to be important to waterfowl wi 11 be flooded,
nor will the important prey species of the upland tundra areas be
affected. Impacts of other types of habitat alteration will depend on
the type of alter·ation. Potential impacts can be lessened through
avoidance of sensitive areas.
Thirteen smart mammal species were found during 1980, and the presence
of three others was suspected. During the fall survey, red-backed
voles and masked shrews were the most abundant species trapped; and
these, plus the dusky shrew, appeared to be habitat generalists,
occupying a wide range of vegetation types. Meadow voles and pygmy
shrews were least abundant and the most restricted in their habitat
use, the former occurring only in meadows and the latter in forests.
(b) Vegetation
The Upper Susitna River Basin is located in the Pacific Mountain physio-
graphic division in southcentral Alaska (Joint Federal-State Land Use
Planning Commission for Alaska 1973). The Susitna River drains parts of
the Alaska Range on the north and parts of the Talkeetna Mountains on the
south. Many areas along the east-west pm'tion of the river, between the
confluences of Portage Creek and the Oshetna River, are steep and covered
with conifer, deciduous and mixed conifer, and deciduous forests. Flat
benches occur at the tops of .these banks and usually contain low shrub or
woodland conifer communities. Low mountains rise from these benches and
contain sedge-grass tundra and mat and cushion tundra.
The southeastern portion of the study area between the ~usitna River and
Lake Louise is characterized by extensive flat areas covered with low
shrubland and woodland conifer communities. These are often intermixed
and difficult to distinguish in the field or on aerial photographs becatJse
of i ntergr adati ons. The area between the Mac 1 aren River and the Denali
Highwa~.t along the Susitna River is covered with woodland and open spruce
stands~ Farther east, the area has more low shl~ubland cover. The
7-12
'
Clear Mountains north of the Denali Highway have extensive tundra
vegetation. The floodplain of the Susitna-River north of the Denali
Highway has woodland spruce and willow stands. The Alaska Range contains
most of the permanent snowfields and glaciers in the study area.
If proposed maximum pool elevations are required~ the Devil Canyon (mapped
at the 1500 ft elevation) and \~atana {mapped at the 2200 ft elevation)
reservoirs will inundate approximately 3603 and 15,885 ha of area
respectively; 2753 and 13,669 ha, respectively, are vegetated (Table 7 .. 7).
A total of 18,109haof vegetation will b~ lo!jt if al1 borrow areas
(outside the impoundment areas) are a1so totally utilized. Borrow sites
may eventually be revegetated, however. The 1&~109 h a of impacted
vegetation represents roughly 1.2 percent cf the total vegetated area in
the Upper Susitna River Basin.
Assuming maxi mum imp act i fl the impoundment and borrow areas, the
vegetation/habitat types which wi 11 he 1 ost (and the apparent percent each
is of the total available in the entire basin) ate presented in Table 7. 7.
Pr:oblems created by comparing maps of two different scales resulted in
apparent percentages of overlap which are highly inflated for the
comparison of birch forests in the impact areas with that of their
availability of the overa11 basin. However:i it r.an safely be said that
birch forests will be substantially impacted by the project, relatively
more so than any other vegetation/habitat type. The only other types which
would recieve relatively substantial impact are open and closed
conifer-deciduous forests and open and closed balsam poplar stands.
The access road or rai 1 road wi 11 destroy an addition a 1 150 to 300 h a of
vegetation, depending of the route selected, and assuming access is from
one direction only and a 30m wide roadbed is utilized. Three-hundred
hectares is roughly equal to 0.02 percent of the vegetation in the entire
basin. The primary vegetation t.ypes to be affected are mat and cushion
tundra, sedge-gras~ tundra~ birch shrubland and woodland spruce.
Preliminary observations indicate that the impoundments and alternative
routes are well below the elevation where potential threatened or
endangered species might occur.
c) Cultural Resource~
The archeological study presently being conducted as part of the Susitna
Hydroelectric program is th.e only intensive archeological survey to have
been conducted in the Upper Susitna Basin. The archeological data gathered
from thi .s study wi 11 greatly add information and understanding of
prehistoric native populations in central Alaska.
7-13
The 1980 at"cheo1ogical reconnaissance, in the Susitna Hydroelectric Project
area, located and documented 40 prehistoric sites and one historic site.
It is expected that continued reconnaissance surveys in 1981 wi 11 1 ocate
additional sites. Sites are also documented adjacent to the study area
near Stephan Lake, Fog Lakes, Lakes Susitna, Tyone and Louise, and along
the Tyone River. Determinations of significance of sites will be based on
the intensive testing data collected during the summer of 1981 and national
register criteria which determine eligibility for the nationai register of
historic p 1 aces.
Geological studies generated data that were used in selecting archeological
survey locals. Data concerning surficial geological deposits and glacial
events of the last glaciation were compiled and provided limiting dates for
the earliest possible human occupation of the Upper Susitna Valley. This
is the first time this type of study has been done in this area.
Paleontological studies were conducted that identified the Watana Creek
area as a tertiary basin with a fossil bearing deposit. A tertiary basin
is unique in the region thereby making this basin a significant site for
obtaining data on regional tertiary flora and fauna.. ·
Impacts on cultural resources will vary in relation to the type of
activities that occur on or near them. Within the Devil Canyon, Watana Dam
study area it is expected that with the development of this scheme
approximately half of the cultural resource sites wouid receive direct
impact and the other half indirect impacts. The Watana Creek tertiary
basin would also be inundated.
Si nee few reconnaissance surveys have been conducted outside the Devi 1
Canyon/Watana Dam study area, the precise number of sites that would be
impacted by a High Devi 1 Canyon/Vee Scheme cannot be listed at this time.
However, preliminary data analyses indicate a clear number of archeological
sites toward the east end of the study area. In addition, there is a high
potentia 1 for many more sites a 1 ong the 1 akes, streams and rivers in this
easterly region of the Upper Susitna River B~sin. Additional sites could
be expected near caribou crossings of the Oshetna River. In summary, a
preliminary assessment of available information suggests that there perhaps
could be a greater number of archeological sites associated with High Devil
Canyon/Vee Scheme than the Watana/Devil Canyon Scheme~
(d) Socioeconomics
As part of the Susitna Hydroelectric program a socioeconomic program has
been implemented to identify the socioeconomic factors that will be
affected and to determ.:tne the extent to which they wi11 be impacted. The
results of this study will also provide input into the selection of the
type and location of certain project facilities.
{i) Population
The Southcentral Railbelt area of Alaska contains the State's two
largest population centers, Anchorage and Fairbanks. Preliminary 1980
census figures indicate the Railbelt contained 280,511 people, 71
7-14
percent of the state population of 400,331. The state population has
increased approximately 30 percent since 1970. The Mat-Su borrow area
had a 1980 population of 17,938 and Valdez-Cordova-8,546.
Housing in the Mat-Su Burrow is primarily single family year round
units. Vacancy rates for Mat-Su Borough, Fairbanks, and Anchorage
were 5.5% (289 units) 9.1% (1,072 units) and 10.2% (5,729 units)
respectively. In addition to year round units, Mat-Su Borough has
1,141 recreational units.
(ii) Economics
Both Anchorage and Fairbanks are regional economic centers for the
Southcentral Railbelt area. Government, trade, and services comprise
the major ·portion of the area's total employment. Construction and
transportation are also important. Making relatively less significant
contributions are the financing, mining, and manufacturing industries,
while agriculture, forestry, and fisheries contribute even less.
After government, the two groups having the largest employment are
trade and services. Their importance as sources of employment for the
Railbelt area residents is a further manifestation of the region's two
relatively concentrated population centers and of the high degree of
economic diversity, as well as levels of demand for goods and
services, which are substantially higher than in most other parts of
Alaska. The importance of construction is largely due to the high
level of expansion experienced by the Anchorage and Fairbanks areas
since 1968. This growth was partly attributable to the trans-Alaska
pipeline project. Consideration of additional natural resource
exploitation projects is continuing to encourage increased
construction activities.
High levels of employment in the region's transportation industry
reflect the positions of Anchorage and Fairbanks as major transporta-
tion centers, not only for the Southcentral Railbelt area but for the
rest of the State as well. The Port of Anchorage handles most of the
waterborne freight moving into southcentral and northern Alaska.
Internati ona·l airports at Anchorage and Fairbanks serve as hubs for
commercial air traffic throughout Alaska and are important stopovers
for major international air carriers. Anchorage also serves as the
transfer point for goods brought in the area by air and water, which
are then distributed by air transport, truck or by Alaska Railroad to
more remote areas.
Valdez is the states largest port handling an annual tonnage of 60
million tons. Ninety-seven percent of this involves the shipment of
crude petroleum from the pipeline. The ports of Anchorage and Valdez
handle 2.2 million tons and 0.4 million tons respectively.
Although exerting relatively little direct impact on total employment,
mining, finance, insurance, and real estate play important roles in
terms of the secondary employment they generate in the region.
7-15
"' ,,
,,,
Most agricultural activities in the Southcentral Railbelt area take
place in the Matanuska, Susitna, and Tanana Valleys. The potential
for agricultural in these areas of Alaska is considered favorable,
although development of the industry has not been extensive.
Commercial fisheries activity is the oldest cash-based industry of
major importance within the region. The industry has changed
substantially during the past 20 years and continues to be modified as
a result of both biologic and economic stimuli. The salmon industry
has always been a major component of the industry in terms of volume
and value. Since 1955, the king crab, shrimp, and Tanner crab
fisheries have undergone major development, and halibut landings have
increased substantially in recent years. The total wholesale value of
commercial fish and shell-fish for the domestic fishery of Alaska in
1979 was just over $1.2 billion including a catch of 459 million
pounds of salmon with a wholesale value of just over $700 million.
The tourist industry plans an increasingly important role in the
economy of Alaska. In 1977 approximately 504,000 people visited
Alaska spending a total of $374 million.
(e) Transportation
( i )
( i i )
Rail. The Alaska Railroad runs from Seward on the Gulf of Alaska,
past Anchorage, up the Susitna Valley, past Mount McKinley National
Park, and down to Fairbanks on the Tanana River, a distance of 483
miles. The Federally constructed and operated Alaska Railroad was
built between 1914 and 1923. Annual traffic volume varies between 1.8
and 2.3 million tons. Coal and gravel account for 75% of this. The
system is operating at only 20% of its capacity.
Roads. Paved roads in the Railbelt area include: the 227-mile
Sterling-Seward Highway between Homer and Anchorage, with a 27-mile
side spur to Seward; the newly-constructed 358-mile Parks Highway
between Anchorage and Fairbanks; a 205-mile section of the Alaska
Highway that connects Tok Junction with Fairbanks; the 328-mile Glenn
Highway connecting Anchorage with Tok Junction; and the 226-mile
Richardson Highway from Valdez, on Prince William Sound, to its
junction with the Alaska Highway at Delta Junction, 97 miles southeast
of Fairbanks.
The only road access through the upper Susitna basin is the 135-mile
gravel Denali Highway between Paxson on the Richardson Highway and
Cantwell on the Parks Highway, and the 20-mile gravel road from the
Glenn Highway to Lake Louise. The Denali Highway is not open for use
during the winter months.
(iii) Air. In addition to major airlines within Alaska, there are numerous
small commerical operators plus the highest per capita ratio of
private aircraft in the nation. Many small remote landing strips are
scattered throughout the Susitna basin, and float planes utilize many
lakes and streams to ferry freight and passengers to the remote
back-country areas. In many areas of the State, the only access is
provided by the airplane.
7-16
(iv) Other Forms of Transportation. ATVs and other types of off-road
vehicles provide transportation into area~ in the upper Susitna basin
where there are no developed roads. Several developed trails are
shown on maps of the upper basin. Trai 1 s are utili zed by ATVs, trai 1
bikes, hikers, horseback riders, and winter travelers.
Shallow-draft river boats, small boats, canoes, rubber rafts, and
kayaks utilize sections of the upper Susitna River, a few tributary
streams, Lake Louise, and some of the other lakes for recreation
purposes. Except for these few areas, boating use is practically
nonexistent within much of the upper basin.
(f) Land Use
Existing land use in the Susitna Project area is characterized by broad
expanses of open wilderness areas. Those areas where development has
occurred often included small clusters of several cabins or other
residences. There are also many single cabin settlements throughout the
basin.
Most ~f the existing stru:tures are related to historical development of
the area involving initially, hunting, mining, and trapping and later .
guiding activities associated with hunting and to a lesser extent fishing.
Today there are a few lodges mostly used by hunters and other recrea-
tionalists. Many lakes in the area also included small clusters of private
year round or recreational cabins.
There are apprximately 109 structures within 18 miles of the Susitna River
between Gold Creek and the Tyone River. These included 4 lodges involving
s.ome 21 structures. A significant concentration of residences, cabins or
other structures are found near the Otter lake area, Portage Creek, High
Lake, Gold Creek, Chunila Creek, Stephan Lake, Fog Lake, Tsusena Lake,
Watana. Lake, Cl ar~nce Lake and Big Lake.
Perhaps the most significant use activity for the past 40 years has been
the study of the Susitna River for potential hydro development. Hunting,
boating, and other forms of recreation are a 1 so important uses. There are
numerous trails throughout the basin used by dog sled, sno~mobile and
ATV's. Air use is significant for many lakes providing landing aret.s for
planes on floats.
There has been little land management activity for the area. However,
Federal and State agencies, native corporations and the private sector have
been involved heavily in the selection and transfer of land ownership under
the Alaska Statehood and the Alaska Native Claims settlement Act. Most of
the lands in the projec~ area and on the south side of the river have been
selected by the native corporation. Lands to the north are generally
federal and managed by BLM.
7-17
TABLE 7.1 -SUMMARY OF CLIMATOLOGICAL DATA
MEAN MONTHLY PRECIPITATION IN INCHES
STATION JAN FEB MAR APR MAY JUNE JULY AUG SEPT OCT NOV DEC ANNUAL
Anchoraoe 0.84 0.56 0.56 0.56 0.59 1.07 2.07 2.32 2.37 1.43 1.02 1.07
Big Delta 0.36 0.27 0.33 0.31 0.94 2.20 2.49 1.92 1.23 0.56 0.41 0.42 11.44
Fairbanks 0.60 0.53 0.48 0.33 0.65 1.42 1.90 2.19 1.08 0.73 0.66 0.65 11.22
Gulkana 0.58 0.47 0.34 0.22 0.63 1. 34 1.84 1.58 1. 72 0.88 o. 75 0.76 11 • 11
Matanuska Agr.
Exp. Station 0.79 0.63 0.52 0.62 0.75 1.61 2.40 2.62 2.31 1.39 0,93 0.93 15.49
McKinley Park 0.68 0,61 0.60 0.38 0.82 2.51 3.25 2.48 1.43 0.42 0.90 0.96 15.54
Summit WSO 0.89 1.19 0.86 0.72 0.60 2.18 2.97 3.09 2.56 1. 57 1. 29 1.11 19.03
Talkeetna 1.63 1. 79 1.54 1.12 1.46 2.17 3.48 4.89 4.52 2.54 1. 79 1.71 28.64
MEAN MONTHLY TEMPERATURES
Anchoraqe 11.8 17.8 23.7 35.3 46.2 54.6 57.9 55.9 48.1 34.8 21.1 13.0
Big Delta -4.9 4.3 12.3 29.4 46.3 57.1 59.4 54.8 43.6 25.2 6.9 -4.2 27.5
Fairbanks -11.9 -2.5 9.5 28.9 47.3 59.0 60.7 55.4 44.4 25.2 2.8 -10.4 25.7
Gulkana -7.3 3.9 14.5 30.2 43.8 54.2 56.9 53.2 43.6 26.8 6.1 -5.1 26.8
Matanuska Agr.
Exp. Station 9.9 17.8 23.6 36.2 46.8 54.8 57.8 55.3 47.6 33.8 20.3 12.5 34.7
McKinley Park -2.7 4.8 11.5 26.4 40.8 51.5 54.2 50.2 40.8 23.0 8.9 -0.1[ 25.8
Summit WSO -0.6 5.5 9,7 23.5 37.5 48.7 52.1 48.7 39.6 23.0 9,8 3.0 25.0
Talkeetna 9.4 15.3 20.0 32.6 44.7 55.0 57.9 54.6 46.1 32.1 17.5 9.0 32.8
Reference 4
TABLE 7.2-RECORDED AIR TEMPERATURES AT TALKEETNA AND SUMMIT IN "F
N
talkeetna Summ1t
Daily Daily Monthly Daily Daily Monthly
Month Max. Min. Average Max. Min. Average
Jan 19.1 -0.4 9.4 5.7 -6.8 -0.6
Feb 25.8 4.7 15.3 12.5 -1.4 5.5
Mar 32.8 7.1 20.0 18.0 1.3 9.7
Apr 44.0 21.2 32.6 32.5 14.4 23.5
May 56.1 33.2 44.7 45.6 29.3 37.5
June 65.7 44.3 55.0 52.4 39.8 48.7
Jul 67.5 48.2 57.9 60.2 43.4 52.1
Aug 64.1 45.0 54.6 56.0 41.2 48.7
Sept 55.6 36.6 46.1 46.9 32.2 39.6
Oct 40.6 23.6 32.1 29.4 16.5 23.0
Nov 26.1 8.8 17.5 15.6 4.0 9.8
Dec 18.0 -0.1 9.0 9.2 -3.3 3.0
Annual Average 32.8 25.0
7-19
TABLE 7.3-MAXIMUM RECORDED ICE THICKNESS ON THE SUSITNA RIVER
Location
Susitna River at Gold Creek
Susitna River at Cantwell
Talkeetna River at Talkeetna
Chulitna River at Talkeetna
Maclaren River at Paxson
7-20
Maximum Ice Thickness
(Feet)
5.7
5.3
3.3
5.3
5.2
MONTH
JANUARY
FEBRUARY
MARCH
APRIL
MAY
JUNE
JULY
AUGUST
SEPTEMBER
OCTOBER
NOVEMBER
DECEMBER
ANNUAL -cfs
TABLE 7.4-AVERAGE ANNUAL AND MONTHLY FLOW AT GAGE
IN THE SUSiTNA BASIN
STATION (USGS Reference Number
Susitna River Susitna River Susitna River Maclaren River
at Gold Creek Near Cantwell Near Denali Near Paxson
(2920) (2915) (2910) (2912)
% Mean(cfs) % Mean(cfs) % Mean(cfs) % Mean(cfs)
1,438 824 245 1 90
1,213 722 204 78
1,085 1 692 187 71
1,339 1 853 1 233 1 82
12 13,400 10 7,701 6 2,063 7 845
24 28,150 26 19,330 23 7,431 25 2,926
21 23,990 23 16,890 29 9,428 27 3,171
19 21,950 20 14,660 24 7,813 22 2,557
12 13,770 10 7,BOO 10 3,343 10 1' 184
5 5,580 4 3,033 3 1 '138 3 407
2 2,435 2 1,449 2 502 168
2 1 '748 1 998 318 111
9,610 6,300 2,720 975
7-21
TABLE 7.5 -FLOOD PEAKS AT SELECTED GAGING STATIONS ON THE SUS!TNA RIVER
Annual Flood Peaks -cfs
Drainage ean
Station (USGS No.) Area-mile 2 Annual 1:100 yr 1:10,000 yr Peaks -cfs
Gold Creek Gage ( 2920) 6,160 53,000 118,000 185,000 106,000
Cant we 11 Gage (2915) 4,140 33,700 68,000 118,000 61! 700
Denali Gage (2910) 950 17,800 43,600 63,000 36,600
7-22
TABLE 7.6-SUSPENDED SEDIMENT TRANSPORT
Sediment Initial
Transport Unit Weight
Station (Tons/year) (Lb/ft 3 )
Susitna at Gold Creek 8,734,000 65.3
Susitna near Cantwell 5,129' 000 70.6
Susitna near Denali 5,243,000 70.4
Maclaren near Paxson 614,000 68.6
7-23
TABLE 7.7-DIFFERENT VEGETATION TYPES FOUND IN THE SUSITNA BASIN
Hectares of vegetation types to be impacted compared with total hectares of those types.
Woodland spruce
Open spruce
Open birch
Closed birch
Open conifer-deciduous
Closed conifer-deciduous
Open balsam poplar
Closed balsam poplar
Wet sedge grass
and cushion tundra
Tall shrub
Birch shrub
Willow
Low mixed shrub
Lakes
Rivers
Rock
Total Areas
NOTES:
Impoundments
Devil Canyon Watana A
162 (0.09)1
862 (0.73)
73 (0.73)
470 2
300 (1.28)
758 (4.75)
73
10 3
12 (0.25)
19 (0.01)
58 (0.17)
16 (0.015)
6 (+)
1 (+)
B35 (5.69)
14 (0.01)
3603 (0.22)
4766 (2.53) 228 (0.12)
3854 (3.24) 48 (0.04)
318 (2.85)
491 2
1329 (5.68)
869 (5.44)
23
100 (2.07)
580 (0.45)
474 (1.41)
55 (0.52)
785 (0.15)
47 (0.22)
2106 (14.35)
63 (0.06)
15839 (0. 97)
6 (0.12)
78 (0.12)
18 (0.01)
18 (0.05)
101 (0.02)
3 (0.01)
500 (0.03)
c
77 (0.04)
7 (0.01)
23 (0.22)
92 (0.27)
113 (0.02)
10 (0.07)
322 (0.03)
Borrow Areas
D
15 (0.01)
12
19 (0.08)
2 (0.01)
(0.02)
8 (0 .01)
73 (0.22)
109 (0.02)
(+)
228 (0.01)
F
9 (0.04)
55 (0.01)
1 (+)
6 (0.04)
71 (+)
Numbers in parentheses are the percent of the vegetation as found in the entire Upper Susitna Basin.
H
227 (0.12)
125 (0.11)
94 (0.40)
7 (0.07)
46 (0.01)
499 (0.03)
Upper Susitna
River Basin
188,391
118,873
968
323
23,387
15,969
4,839
65,001 3 4
129,035
33,549
10,645
471 ,461
21 '162
14,678
113 712
1,211,992
( 1 )
(2) Hectares of closed birch are apparently greater in the impact areas (mapped at a scale of 1:24,000) than for the entire basin
(mapped at a scale of 1:2)0,000), because the basin was mapped at a much smaller scale, and many of the closed birch stands
did not appear at that scale.
(3)
(4)
Balsam poplar stands were too small to be mapped at the scale of which the Upper Susitna River Basin was mapped.
Total hectares of mat and cushion tundra are much greater than this, but many hectares were mapped as a complex with
sedge-grass tundra.
---J
I
N
U1
5 0 5
SCALE IN MILES
15
~
TYONE & DAMSITE
CANTWELL • STREAMGAGE
SUMMIT \J CLIMATE
'\]SUMMIT
DATA COLLECTION STATIONS
J_" ............... _..v _,
,.-----
/
J
PAXSON6
_./ GULKANA'\J
FIGURE 7.1 IIRI
CHULITNA RIVER
YENTNA RIVER
39°/o
SUSITNA RIVER
DEVIL WATANA
CANYON SITE SITE
1iL 20o/~1 GOLD CREEK
too 0/o
COOK INLET
TALKEETNA RIVER
:::
. :;:;:
PARKS HIGHWAY BRIDGE
GAGING STATION
SUSITNA GAGING STATION
AVERAGE ANNUAL FLOW DISTRIBUTION
WITHIN THE SUSITNA RIVER BAStN
FiGURE 7. 2
50,000
LEGEND
-Q 40,000 WETTEST YEAR-1962
2
0
(..) AVERAGE YEAR w
(/)
0:: w a.. DRIEST YEAR -1969
-......J 1-30l000 I
N w
-.....:! w
lL.
(..)
m
:::>
(..) -
~ 20,000
0
..J
lJ..
~
<! w ..
0::
t-
(/)
10,000
0
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
MONTHLY AVERAGE FLOWS IN
THE SUSITNA RIVER AT GOLD CREEK
FIGURE 7.3 --
R llW
T33N
T 31 N
T
32
N
T
31
N
T
30
N
z
<C cs
a: w
:E
0 a: ~~~~~~~~~~~~~~~~~~~~~*rr*rrAn~~~~~'*"~r--~----~~~~
Modified from Csejtey, et al, 1978
w
tf)
• •
CENOZOIC
QUATERNARY r---,
I I ._ ___ ,
TERTIARY
MESOZOIC
CRETACEOUS E..::.-:::-=-::-1 r-_-_-_-::_ -_-:s
t--.:..-.:..---:... --:J
JURASSIC
rnmrro
LEGEND
UNDIFFERENTIATED SURFICIAL DEPOSITS
UNDIFFERENTIATED VOLCANICS 8 SHALLOW
INTRUSIVES
GRANODIORITE,
BIOTITE-HORNBLENDE GRANODIORITE,
BIOTITE GRANODIORITE
SCHIST, MIGMATITEt GRANITIC ROCKS
UNDIVIDED GRANITIC ROCKS
MAFIC INTRUSIVES
ARGILLITE /~NO LITHIC GRAYWACKE
f7\ 7\ !\/'\*~ :.6 A A 6,!!1
TRIASSIC
~z-;....., tN
.~...\>"..>..,, _____ ,_,
PALEOZOIC
AMPHIBOLITES, GREENSCHIST, FOLIATED DIORITE
BASALTIC METAVOLCAN JC ROCKS, META BASALT
AND SLATE
BASALTIC TO ANDESITIC META VOLCANICS LOCALLY
INTERBEDDED WITH MARBLE
THRUST FAULT TEETH ON UPTHROWN SIDE,DASHED WHERE
---··--y • • • OOTTED WHERE CONCEALED
INTENSE SHEARING ••• '\1 •••• \1 •• POSSIBLE THRUST FAULT, TEETH ON UPTHROWN
• SIDE
'\f PROPOSED DAM SITES
o 2 4 6 a ~P-1~-~-jjliM~-.z--~--il-~. 5;-~~~~-........ .
SCALE IN r:41LES
GRANODIORITE, QUARTZ DIORITE, TRONDHJEMITE
REGIONAL GEOLOGY FIGURE 7.4
LOCATION MAP
LEGEND:
CENSUS AREA
ZERO DENSITY
LOW DENSITY
MEDIUM DENSITY
HIGH DENSITY
10 0 IO 30
SCALE IN MILES
RELATIVE DENSITIES OF MOOSE -NOVEMBER, 1980
FIGURE 7. 51 ~~IR I
'-l
I w
0
LOCATION MAP
MODIFIED FROM REFERENCE (
WINTER DISTRIBUTION OF MOOSE -MARCH, 1980
10 0 10 30
SCALE IN MILES
FIGURE 7.6 IiiJ
LOCATION MAP
LEGEND:
m WATANA PACK
~ TYONE PACK
mJ]J]] SUSITNA PACK
~ TOLSONA PACK
-r--,
..) I I SUSPECTED PACK L __ ...J
10 0 10 30
SCALE IN MitES
LOCATION AND TERRITORIAL BOUNDARIES OF WOLF PACKS -1980
FIGURE 7.7
LIST OF REFERENCES
(1} Gedney~ L~ and Shapiro, L., Structural Lineaments, Seis~icity and Geology
of the Talkeetna Mountains Area, Alaska, U.S. Army Corps of Engineers,
1975. .
(2) Csejtey, B. Jr., et al. 11 Reconnaissance Geology Map and Geochronology,
Talkeetna ~10untain Quadrangle, Northern Part of Anchorage Quadrangle, and
Southwest Corner of Healy Quadrangle, Alaska 11 , U.S. Geological Survey, Open
File Report, 78-558A.
(3) Alaska Department of Fish and Game, 1980 Draft Annual Report.
(4) U.S. Department of Commerce, National Oceanic and Atmospheric
Administration, Environmental Data Section, Local Climatological Data.
7-32
8 -SUSITNA BASIN DEVELOPMENT SELECTION
This section of the report outlines the engineering and planning studies carried
out as a basis for formulation of Susitna Basin development plans and selection
of th~ preferred plan. The selection process used is consistent with the gener-
ic plan-formulation and selection methodology discussed in Section 1.4 and
Appendix A. The recommended plan, the \~atana/Devil Canyon dam project, is com-
pared to alternative methods of generating Railbelt energy needs including ther-
mal and other potential hydroelectric developments outside the Susitna Basin on
·the basis ef technical, economic, environmental and social aspects ..
8.1 -Terminology
In the description of the planning process, certain plan components and process-
es are frequently discussed. It is appropriate that three particular terms be
clearly defined:
(a) Dam Site
(b) Basin Develoement
Plan
(c) Generation
Scenario
-An individual potential dam site in the Susitna Basin,
equivalent to "alternative" and referred to in the
generic process as "candidate".
- A plan for developing energy within the basin involv-
ing one or more dams, each of specified height, and
corresponding power plants of specified capacity.
Each plan is identified by a plan number and subnumber
indicating the staging sequence to be followed in
developing the full potential of the plan over a
period of time. These are equivalent to the uplans"
referred to in Appendix A.
- A specified sequence of implementation of power gen-
eration sources capable of providing sufficient power
and energy to satisfy an electric load growth forecast
for the 1980-2010 period in the Railbelt area. This
sequence may include different types of generation
sources such as hydroelectric and coal, gas or oil-
fired thermal. These generation scenarios are
required for the comparative evaluations of Susitna
Basin generation versus alternative methods of
generation.
8.2 -Plan Formulation and Selection Methodology
As outlined in the description of the generic plan formulation and selection
methodology (Appendix A) five basic steps are required. These essentially con-
sist of defining the objectives, selecting candidates, screening, formulation of
development plans and finally, a detailed evaluation of the plans.
The objectives of the studies outlined in this section are essentially twofold,
8-1
The first is to determine the optimum Susitna Basin development plan, and the
second is~ to undertake a preliminary assessment of the feasibility of the
selected plan by comparison with alternative methods of generating energy.
Studies carried out to meet the first objective follow the prescribed method-
ology and are outlined in the following subsections. Step 2 of the methodology,
which calls for the selection of candidate dam sites, is outlined in Section
8.3. Step 3, screening, is discussed in 8.4 while Subsection 8.6 deals with
Step 4, plan formulation. The final step, plan evaluation, is dealt with in
Subsection 8.6. Figure 8.1 illustrates the process and highlights the data
sources and techniques used for plan formulation and evaluation5
Throughout this planning process, engineering layout studies were conducted to
refine the cost estimates for power or water storage development at several dam
sites within the basin {Section 8.5}.. As they became available, these data were
fed into the screening and plan formulation and evaluation studies.
The second objective is satisfied by comparing generation scenarios that include
the selected Susjtna Basin development plan with alternative generation scenar-
ios including all-thermal and a mix of thermal plus alternative hydropower
developments. The selection and screening of alternative hydropower thermal
units and developments is discussed in Sections 6.4 and 6.5 respectively. The
plan formulation step which involves developing the alternative generating
scenarios is outlined in Section 8.7 below. The final evaluation of the plans
is also discussed in Section 8.72
8.3 -Dam Site Selection
In the previous Susitna Basin studies discussed in Section 4, twelve dam sites
were ~identified in the upper portion of the basin, i.e. upstream from Go1d Creek
(see Figure 4.1). These sites are listed below:
-Gold Creek
-Olson (alternative name: Susitna II)
-De vi 1 Canyon
-High Devil Canyon (alternative name: Susitna I}
-De vi 1 Creek
-Watana
-Susitna III
-Vee
-Maclaren
8-2
-Denali
-Butte Creek
-Tyone
Fig~~re 8.2 shov1s a longitudinal profile of the Susitna River and typical reser-
voir levels associated with these sites. Figure 8.3 illustrates which sites are
mutually exclusive, i.e. those which cannot be developed jointly since the
downstream site would inundate the upstream site.
All re 1 evant data concerning dam type, capita 1 cost, power, and energy output
were assembled and are summarized in Table 8.1. For the Devil Canyon, High
Devil Canyon, Watana, Susitna III, Vee, Maclaren and Denali sites conceptual
engineering layouts were produced and the capital cost estimated based on
calculated quantities and unit rates. Detailed analyses were also undertaken to
assess the power capability and energy yields. At the Gold Creek, Devil Creek,
Maclaren, Butte Creek, and Tyone sites, no detailed engineering or energy
studies were undertaken and data from previous studies were used with capital
cost estimates updated to 1980 levels. Approximate estimates of the potential
average energy yield at the Butte Creek and Tyone sites were undertaken to
assess the relative importance of these sites as energy producers.
The results in Table 8.1 show that Devil Canyon, High De vi 1 Canyon, and Watana
are the most economic large energy producers in the basin. Sites such as Vee
and Susitna III are medium energy producers, although slightly more costly than
the previously mentioned dam sites. Other sites such as Olson and Gold Creek
are competitive provided they have additional upstream regulation. Sites such
as Dena 1 i and Maclaren produce substantially higher cost energy than the other
sites but can a 1 so be used to ·j ncr ease regulation of flow for downstream use.
For comparative purposes the capital cost estimates developed in recent previous
studies, updated to 1980 values, are listed alongside the costs developed for
the current studies (Table 8.2). These results show that the current estimates
are generally slightly higher than previous estimates and, except in the case of
Vee, differences are within 15 percent.
At Devil Canyon current total development costs are similar to the 1978 COE es-
timates. Although the estimates involve different dam types, current studies
have indicated that at a conceptual level the cost of development at this site
is not very sensitive to dam type. The results in Table 8.2, therefore"
indicate r-elative agreement. Costs developed for the High Devil Canyon dam site
are very close while those at Watana exceed previous estimates by about 15
percent. A tnajor difference occurs at Vee where current estimates exceed those
deve 1 oped by the COE by 40 percent. A 1 arge portion of this difference can be
ascribed to the greater level of detail incorporated in the current studies as
compared to the previous work and the more extensive foundation excavation and
treatment that have been assumed. This additional foundation work is consistent
with a standard set of design assumptions used for developing all the site
1 ayouts reported here. S(~cti on 8. 4 and Appendix D discuss these aspects in more
detail.
8-3
8.4 -Site Screening
The objective of this screening exercise is to eliminate sites which would ob-
viously not feature the initial stages of a Susitna Basin development plan and
which, therefore, do not require anY further study at this stage. Three basic
screening criteria are used; these include environmental, alternative sites~ and
energy contribution ..
(a) Screening Criteria
(i) Environmental
The potential impact on the environment of a reservoir located at
each of the sites was assessed and catagorized as being relatively
unacceptable, significant or moderate.
-Unacceptable Sites
Sites in this category are classified as unacceptable because either
their impact on the environment would be extremely severe or there
are obviously better alternatives available. Under the current cir-
cumstances, it is expected that it would not be possi~le to obtain
.the necessary agency approval, permits~ and licenses to develop
these sites.
The Gold Creek and Olson sites both fall into this category. As
salmon are known to migrate up Portage Creek, a development at
either of these sites \·JOuld obstruct this migration and inundate
spawning grounds. Available information indicates that salmon do
not migrate through Devil Canyon to the river reaches beyond because
of the steep fall and high flow velocities.
Development of the mid reaches of the Tyone River would result in
the inundation of sensitive big game and waterfowl areas, provide
access to a large expanse of wilderness area, and contribute only a
small amount of storage and energy to any Susitna development.
Since more acceptable alternatives are obviously available, the
Tyone site is also considered unacceptable.
-Sites With Significant Impact
Between Devil Canyon and the Oshetna River the Susitna River is con-
fined to a relatively steep river valley. Upstream of the Oshetna
River the surrounding topography flattens and any.development in
this area has the potential of flooding large areas even for rela-
tively low dams. Although the Denali Highway is relatively close
by, this area is not as isol at-cd as the Upper Tyone River Basin,. It
is still very sensitive in terms of potential impact on big game and
waterfowl. The sites at Butte Creek, Denali, Maclaren, and, to a
lesser extent Vee, fit into this category.
8-4
-Sites With Moderate Impact
Sites between Devil Canyon and the Oshetna River have a lower poten-
tial environmental impact. These sites include the Devil Canyon,
High Devi·I Canyon, Devil Creek, Watana and Susitna sites, and, to a
lesser extent, the Vee site.
{ii) Alternative Sites
Sites which are close to each other and can be regarded as alternative
dam 1 ocati ons can be treated as one site for project definition study
purposes. The two sites whicheJfall into this category are Devil
Creek, which can be regarded as an alternative to the. High Devil Can-
yon site, and Butte Creek, which is an alternative to the Denali site.
{iii) Energy Contribution
~ The total Susitna Basin Potential has been assessed at 6700 GWh. As
outlined on Table 5.11, additional future energy requirements for the
period 1980 to 2010 are forecast to range from 2400 to 13,100 GWh. It
was therefore decided to limit the minimum size of any power develop-
ment in the Susitna Basin to an average annua 1 energy production. in
the range of 500 to 1000 GWh. The upstream sites such as ~iac 1 aren,
Denali, Butte Creek, and Tyone do not meet this minimum energy
generation criteriono
(b) Screening Process
The screening process involved eliminating all sites falling in the un-
acceptable environmental impact and alternative site categories. Those
failing to meet the energy contribution criteria were also eliminated un-
less they have some potential for upstream regulation. The results of this
process are as follows:
-The 11 Unacceptable site 11 environmental category eliminated the §l>ld Creek,
01 son, and Tyone sites .•
-The alternative sites category eliminated the Devil Creek and Butte Creek
sites.
-No additional sites were eliminated for failing to meet the energy con-
tribution criteria. The remaining sites upstream from Vee, i.e.
Maclaren and Dena 1 i, were retained to ensure that further study be
directed toward determining the need and viability of providing flow
regulation in the headwaters of the Susitna.
8 .. 5 -Engineering Layout and Cost Studies
In order to obtain a more uniform and re 1 i ab 1 e data base for studying the seven
sites remaining, it was necessary to develop engineering layouts for these sites
8-5
and re-evaluate the costs. In addition, it was also necessary to study staged
developments at several of the larger dams.
The basic objective of these layout studies is to establish a uniform and con-
sistent development cost for each site. These layouts are consequently concep-
tual in nature and do not necessarily represent optimum project arrangements at
the sites. Also, because of the lack of geotechnical information at several of
the sites, judgemental decisions had to be made on the appropriate foundation
and abutment treatment. The accuracy of cost estimates made in these studies is
probably in the order of plus or minus 30 percent.
(a) Design Assumptions
In order to maximize standardization of the layouts, a set of basic design
assumptions were developed. These assumptions covered geotechnical, hydro-
logic, hydraulic, civil, mechanical~ and electrical considerations and \'lere
used as guidelines to determine the type and size of the various components
within the overall project layouts. They are described in detail in Appen-
dix D. As stated previously, other than at Watana, Devil Canyon, and
Denali, little information regarding site conditions was available. Broad
assumptions were made on the basis of the limited data, and those assump-
tions and the interpretation of data have been conservative.
It was assumed that the relative cost differences between rockfill and con-
crete dams at the sites would either be marginal or greatly in favor of the
rockfill. The more detailed studies carried out subsequently for the
Watana and De vi 1 Canyon site support this assumption (see Appendix H).
Therefore, a rockfill dam has been assumed at all developments in order to
eliminate different cost discrepancies that might result from a considera-
tion of dam fill rates compared to concrete rates at alternative sites.
(b) §eneral Arrangements
A brief description of the genera 1 arrangements deve 1 oped for the vari O'JS
sites is given below. Plates 1 to 7 illustrate the layout details. Table
8.3 summarizes the crest levels and dam heights considered.
In laying out the developments, conservative arrangements have been
adopted, and whenever possible there has been a general standardization of
the component structures.
( i) De vi 1 Canyon (Plate 1)
-Standard Arrangement
The development at Devil Canyon is located at the upper end of the
canyon at its narrO\':Iest point. It consists of a rockfi 11 dam~ sin-
gle spillway, power facilities incorporating an underground power-
house, and a tunnel diversion.
The rockfi 11 dam rises above the va 11 ey on the 1 eft abutment and
terminates in an adjoining saddle dam of similar construction. The
dam rises 675 feet above the lowest foundation level with a crest
8-6
elevation of 1470 feet and a volume of 20 million cubic yards. It
consists of an inclined impervious core~ filter zones, and an over-
lying rockfill shell. Part of tne shell '!Jill come from excavation
at the site but the majority will be blast rock from local quarries.
It is anticipated that core and filter materials will also be avail-
able locally. The core is founded on sound bedrock, and full
foundation tr·eatrnent is a 11 owed for in the form of contact grouttng 5
curtain gr)outi ng, and drainage vi a a network of shafts and ga 1-
leries. All alluvium and overburden material are removed from the
shell foundation area.
Diversion is effected by two concrete-lined tunnels driven within
the rock on the right abutment. Upstream and downstream rockfill
cofferdams with aqueous trench cutoffs are founded on the river
alluvium and are separated·from the main dam. Final closure is
achieved by lowering vertical lift sliding gates housed in an up-
stream structure followed by construction of a solid concrete plug
within the tunnel in line with the main dam grout curtain. Subse-
quent controlled downstream releases occur via a small tunnel bypass
1 ocated at the gate structure and a ':~owe 11 Bunger valve housed with-
in the concrete plug.
The spi 11way is 1 ocated on the right bank and consists of a gated
overflow structure and a concrete-lined chute linking the overflow
structure with an intermediate and terminal stilling basins. Suf-
ficient spillway capacity is provided to pass the Probable r~aximum
Flood safely.
The power facilities are located on the right abutment. The massive
intake structure is founded within the rock at the end of a deep ap-
proach channel and consists of four integrated units, each serving
individual tunnel penstocks. Each unit has three outlets at
different levels allowing for various levels of drawoff and
corresponding temperature control of releases from the seasonally
fluctuating reservoir. Each outlet is controlled by a pair of
vertical lift wheeled gates and incorporates provision for upstream
guard gates. ·
The penstocks are concrete-lined over their full length except for
the section just upstream of the po~1erhouse which is steel-lined to
prevent seepage into the powerhouse area. The rock in this vicinity
is generally badly fractured by blasting operations during power-
house cavern construction activity.
The powerhouse houses four 100 MW (or 150 MW) vertically mounted
Francis type turbines driving overhead 110/165 MVa umbrella type
generators. These are serviced by two overhead cranes running the
length of the main power hall and an adjacent service bay. The main
power transformers are housed in an underground gallery located
above the draft tubes .. This gallery also houses a gentry crane for
operating the draft tube gate~> required to isolate the individual
draft tubes from the common downstream manifold and tailrace tunnels
during mairitenance. The control room and offices are situated at
the surface adjacent to a surface switchyard.
8-7
-Staged Powerhouse
As an alternative to the full power development~ a staged powerhouse
alternative was also in~estigated. The dam would be completed to
its full height but with an initial plant installed capacity in the
200 to 300 MW range: The complete powerhouse would be constructed
together with concr·ete foundations for the future units, penstocks
and tailrace tunnel for the initial-2-100 MW (or 150 MW) units. The
complete intake would be constructed except for gates and trashracks
required for the second stage. The second stage would include
installation of the remaining gates and racks and construction of
the corresponding penstocks and tailrace tunnel for two new 100 MW
(or 150 MW} units. Civil, electrical, and mechanical installation
fot these units would also be completed within the powerhouse area,
together with the enlargement of the surface switchyard, during the
second stage.
( i i) Watana (Plates 2 and 3)
-Standard Arrangement {see Plate 3)
For initial comparative study purposes, the dam at Watana is assumed
to be a rockfill structure located on a similar alignment to that
proposed in the previous COE studies. It is similar in construction
to the dam at Devil Canyon with an impervious core founded on sound
bedrock and an outer shell composed of blasted rock excavated from a
single quarry located on the left abutment. The dam rises 880 feet
from the lowest point on the foundation and has an overall volume of
approximately 63 million cubic yards. The crest elevation is 2225
feet.
The diversion consists of t\'/in concrete ... lined tunnels located within
the rock of the right abutment. Rockfill cofferdams!t also with im-
pervious cores and appropriate cutoffs, ure founded on the alluvium
and are separated from the main dam.. Diversion closure and facili-
ties for downstream releases are provided for in a manner similar to
that at Devil Canyon.
The spillway is located on the right bank and is similar in concept
to that at Devil Canyon \vith an intermediate and terminal stilling
basin.
The power facilities are located within the left abutment \'lith simi-
lar intake, underground powerhouse and water passage concepts to
those at Devil Canyon. The power facilities consist of four 200 ~1\~
turbine/generator units giving a total outp~:Jt of 800 MH.
-~aging Concepts
As an alternative to initial full development at W.atanct, staging al-
ternatives were investigated. These include staging of both dam and
powerhouse construction. Staging of the powerhouse would be similar
to that at Devil Canyon, vJith a Stage I installation of 400 MW and a
further 400 NW in Stage II. ·
8-8
In order to study the alternative dam staging concept it has been
assumed that the dam would be constructed for a maximum operating
water surface elevation some 200 feet lower than that in the final
stage. (See Plate 3).
The first stage powerhouse would be completely excavated to its fin-
al size. Three oversized 135 MW units would be installed together
with base concrete for an additional unit. A low level control
structure and twin concrete-lined tunnels leading into a downstream
stilling basin would form the first stage spillway.
For the second stage, the dam would be completed to its full height,
the impervious core would be appropriately raised and additional
rockfill would be placed on the downstream face. It is assumed that
before construction commences the top 40 feet of the first stage dam
is removed to ensure the complete integrity of the impervious core
for the raised dam. A second spillway control structure would be
constructed at a higher level and incorporate a downstream chute
leading to the Stage I spillway structure. The original spillway
tunnels would be closed with concrete plugs. A new intake structure
would be constructed utilizing existing gates and hoists, and new
penstocks would be driven to connect with the existing ones. The
existing intake would be sealed off. One additional 200 MW unit
would be installed and the required additional penstock and tailrace
tunnel constructed. The existing 135 MW units would be upgraded to
200 MW. This can be accomplished as described below.
-Staging Generating Equipment
Turbine-generator equipment operates at one particular speed and us-
ually performs at maximum efficiency for a relatively small range of
head variation. If the head varies significantly, the turbine effi-
ciency is reduced, and unit operation may be rougher with increased
potential for cavitation.
The options available for selection of turbine-generator equipment
for staged dam construction are consequently fairly restricted. In
general, these options would include:
o Selection of the turbine and generator so that the equipment will
operate satisfactorily at one intermediate head with some loss of
efficiency during both the initial and final stages;
o Modification of the turbine-generator rotational speed for the
final stage of operation;
o Replacement of the turbine runner for the final stage of
operation;
o Replacement of the runner and modification of turbine-generator
speed for the final stage of operation.
The first option is the simplest alternative from an equipment point
of view. However, the change in head will result in an efficiency
8-9
penalty in one or perhaps both stages of operation. Unless the head
change is relatively smal13 the energy loss due to reduction in
efficiency would out~;Jeigh the additional capital expenditure associ-
ated with the other alternatives for staging.
The second option involves increasing the generator speed when the
reservoir level is raised so as to maintain turbine operation at or
near the best efficiency point during both stages of operation. For
first stage.operation, the unit speed may be selected slightly lower
than normal to avoid excessive speed for the higher head operation.
The generator speed change can be accomplished by changing the
stator winding connections and a 1 so changing the rim and rotor
winding electrical connections to reduce the number of poles. A
change in generator speed would result in a marginal reduction in
generator efficiency.
The third approach involves installing a new runner with a higher
optimum operating head once the dam is completed to its full height.,
Such an option has been used on other projects. For very large
changes in head however, the shape and dimensions of the initial and
final runners vary considerably. This may result in difficulties in
designing the turbine di str i but or to accommodate both runners
without a sacrifice in turbine efficiency.
The fourth method is essentially a combination of the second and
third options, resulting in a change both in the turbine runner and
the unit speed after the dam is raised to its full height. Such an
approach would be suitable for a staging scheme involving a signifi-
cant increase in head.
In addition to the above considerations it should be noted that the
generators, transformers, circuit breakers, bus bars, power trans-
mission cable and ancillary equipment must be selected to accommo-
date the higher capacity \'Jhich will be ava.ilable in the final stage
of operation.
For the staged dam construction at Watana, maximum operating head
would increase from about 520 feet to 720 feet. The units would be
required to operate for. part of the time under substantial dra\tdown
conditions under both stages. Option one would not in this case be
appropriate because of the large range in head involved. Option
four on the other hand is not warranted because it is designed to
cope with much larger head changes than are currently envisaged at
~~atana. Preliminary analyses indicate that of the two options re-
maining, the third would provide the more cost effective solution
for Watanao However, should staged development appear economic,
more detailed studies would be required for the selection of gener-
ating equipment. This refinement is not expected to significantly
affect the over a 11 economics of the staging concept, and ther-efore
is not considered necessary for this phase of the study.
{iii) High Devil Canyon (Plate 4)
The development is located between Devil Canyon and Watana. The dam
is an 855 feet high rockfill dam similar in design to Uevil Canyon,
8-10
containing an estimated 48 million cubic yards of rockfill with a
crest elevation of 1775 feet.. The left bank spillway and the right
bank powerhouse facilities are also similar in concept to Devil
Canyon. The installed capacity is 800 MW. The left bank diversion
system is formed by upstream and downstream earth/rockfill cofferdams
and twin concrete-lined tunnels with typical cutoff and downstream
release facilities.
Staging is envisaged as two stages of 400 MW each in the same manner
as at Devil Canyon with the dam initially constructed to its full
height.
(iv) Susitna III (Plate 5)
The development is comprised of a rockfill dam with an impervious
core approximately 670 feet high. The dam would have a volume of
approximately 55 million cubic yards and a crest elevation of 2360
feet.
The spillway consists of a concrete-lined chute and a single stilling
basin and is located on the right bank.
A powerhouse of 350 MW capacity is located underground and the two
diversion tunnels are located on the left bank.
(v) Vee (Plate 6)
A 610 feet high rockfill dam founded on bedrock with a crest elevation
of 2350 feet and total volume of 10 million cubic yards, has been con-
sidered.
Since Vee is located further upstream than the other major sites the
flood flows are correspondingly lower, thus allowing for a reduction
in size of the spillway facilities. A spillway utilizing a gated
overflow structure, chute, and flip bucket has been adopted and is
located within the ridge forming the right abutment of the dam. . ~
The power facilities consist of a 400 MW underground powerhouse
located in the left bank with a tailrace outlet well dot>mstream of the
main dam. The intake is f0unded in a rock shoulder to the left of the
dam. A secondary rockfill dam is also required in this vicinity to
seal off a low point. Two diversion tunnels are provided on the right
bank.
(vi} Maclaren (Plate 7)
The development consists of a 185 feet high earthfi11 dam founded on
pervious riverbed materials. Crest elevation is 2405 feet. This
reservoir would essentially be used for regulating purposes. Although
generating capacity could be provided a powerhouse has not been shown
in the proposed layout. D-iversion is through three conduits located
in an open cut on the left bank and floods are discharged via a side
chute spillway and stilling basin on the right bank.
8-11
(vii) Denali (Plate 7)
Denali is similar in concept to Maclaren. The dam is 230 feet high,
of earthfill construction, and has a crest elevation of 2555 feet. As
for Maclaren, no generating capacity is shown. A combined diversion
and spillway facility is provided by twin concrete conduits founded in
open cut excavation in the right bank and discharging into a common
stilling basin.
(c) Capital Cost
For purposes of initial comparisons of alternatives, construction
quantities were determined for items comprising the major works and
structures at the sites. Where detail or data were not sufficient for
certain work, quantity estimates have been made based on previous Acres•
experience and the general knowledge of site conditions reported in the
literature. In order to determine total capital costs for various
structures, unit costs have been developed for the items measured. These
have been estimated on the basis of reviews of rates used in previous
studies, and of rates used on similar works in Alaska and elsewhere. Where
applicable, adjustment factors based on geography, climate, manpower and
accessibility were used. Technical publications have also been reviewed
for basic rates and escalation factors.
An overall mobilization cost of 5 percent has been assumed and camp and
catering costs have been based on a preliminary review of construction man-
power and schedules. An annual construction period of 6 months has been
assumed for placement of fill materials and 8 months for all other
operations. Night work has been assumed throughout.
A 20 percent allowance for non-predictable contingencies has been added as
a lump sum together with a typical allowance for large projects of 12
percent for engineering and administration costs.
The total capital costs developed are shown in Tables 8.1, 8.2, and 8.4 •
It should be noted that the capital costs for Maclaren and Uenali shown in
Table 8.1 and 8.2 have been adjusted to incorporate the costs of 55 MW and
60 MW plants respectively.
8.6 -Formulation of Susitna Basin Development Plans
The results of the site screening exercise described in Section 8.3 indicate
that the Susitna Basin development plan should incorporate a combination of
several major dams and powerhouses located at one or more of the following
sites:
-Devil Canyon.
-High Devil Canyon.
-Watana.
-Susitna III.
-Vee.
8-12
In addition, the following two sites should be considered as candidates for
supplementary upstream flow regulation:
-~1aclaren
-Denali
To establish very quickly the likely optimum combination of dams, ~ computer
screening model was used to directly identify the types of plans that are most
economic. Results of these runs indicate that the Devil Canyon/Watana or the
High Devil Canyon/Vee combinations are the most economic. In addition to these
two basic development plans, a tunnel scheme which provides potential environ-
menta 1 advantages by rep 1 acing the De vi 1 Canyon dam by a 1 ong power tunnel and a
development plan involving the two most economic dam sites, High Devi-l Canyon
and Watana, were also introduced. These studies are outlined in more detail
below.
The criteria used at this stage of the process for selection of preferred
Susitna Basin development plans are mainly economic (see Figure 8.1). As
" discus·sed below, environmental considerations are incorporated into the furthei'
assessment of the plans finally selected.
(a) Application of Screening Model
Basically, this computer model compares basin development plans for a given
total basin power and energy demand and selects the sites, approximate dam
heights, and installed capacities on a least cost basis.
The model incorporates a standard Mixed Integer Programning (MIP) algorithm
for determining the optimum or least cost solution. Inputs essentially
comprise basic hydrologic data, dam volume-cost curves for each site~ an
indication of which sites are mutually exclusive, and a total pov1er demand
required from the basin. A time period by time period energy simulation
process for individual sites and groups of sites is incorporated into the
model. The model then systematically searches out the least cost system of
reservoirs and selects installed capacities to meet the specified pm'ier and
energy demand.
A detailed description of the model as well as the input and output data
are giver: in Appendix E. A summary of this information is presented
below:
( i ) Input Data
Input data to the model take the following form:
-Streamfl 0\'1: In order to reduce the camp 1 exi ty of the mode 1 , a year
is divided into two periods, summer and winter, and flows are speci-
fied for each. For the smaller dam sites such as Denali, Maclaren,
Vee, and Devil Canyon, which have little or no overyear storage
capability, only two typi ca 1 years of hydrology are input. These
correspond to a dry year (90 percent probability of exceedence) and
an average year (50 percent probabi 1 ity of exceedence). For the
other larger sites, the full thirty years of historical summer and
winter flows are specified.
8-13
-Site Characteristics: For each site, storage capacity versus cost
curves are provided. These curves were developed from the
engineering layouts presented in Section 8.4. Utilizing these
layouts as a basis, the quantities for lower level darn heights were
determined and used to estimate the costs associated with these
lower levels. Figures 8.4 to 8.6 depict the curves used in the
model runs. These curves incorporate the cost of the appropriate
generating equipment except for the Denali and Maclaren reservoirs,
which are treated solely as storage facilities.
-Basin Characteristics: The model is supplied with information on
the mutually exclusive sites as outlined in Figures 8.4 to 8.6.
-Power and Energy Demand: The model is supplied with a power and
energy demand. This is achieved by specifying a total generating
capacity required from the river basin and an associated annual
plant factor which is then used to calculate the annual energy
demand.
(ii) Model Runs and Results
A review of the energy forecasts discussed in Section 5 reveals that
between the earliest time a Susitna project could come on line (in
early 1993) and the end of the planning period (2010), approximately
2200, 4250, and 9570 Gwh of additional energy would be required for
the low, medium, and high energy forecasts, respectively. In terms of
capacity, these values represent 400, 780, and 1750 MW. Based on
these figures, it was decided to run the screening model for the
following total capacity and energy values:
-Run 1:
-Run 2:
-Run 3:
-Run 4:
400 MW -1750 Gwh.
800 MW -3500 Gwh.
1200 MW -5250 Gwh.
1400 MW -6150 Gwh.
The results of these runs are shown in Table 8.5. Because of the
simplifying assumptions that are made in the screening model, the
three best solutions from an economic point of view are presented.
The most important conclusions that can be drawn from the results
shown in Table 8.5 are as follows:
-For energy requirements of up to 1750 Gwh, the High Devil Canyon,
Devil Canyon or the Watana sites individually provide the most eco-
nomic energy. The difference between the costs shown on Table 8.5
is around 10 percent, which is similar to the accuracy that can be
expected from the screening model.
-For energy requirements of between 1750 and 3500 Gwh, the High Devil
Canyon site is the most economic. Developments at Watana and Devil
Canyon are 20 to 25 percent more costly.
8-14
(b)
-For energy requirements of between 3500 and 5250 Gwh the
combinations of either \~atana and Devil Canyon or High Devil Canyon
and Vee are the most economic. The High Devil/Susitna III
combination is also competitive. Its cost exceeds the Hatana/Devil
Canyon option by 11 percent which is \"iithin the accuracy of the
modele
-The total energy production capability of the Watana/Devil Canyon
developments is considerably larger than that of the High Devil
Canyon/Vee alternative and is the only plan capable of meeting
energy demands in the 6000 Gwh range.
The reasons why this screening process rejected the other sites is as
follows:
Except for the one case, Susitna III is rejected due to its high capi-
tal cost. The cost of energy production at this site is high in com-
parison with Vee, even allowing for the 150 feet of the system head
that is lost between the headwaters of High Devil Canyon and the
tailwater of Vee.
Maclaren and Denali have a very small impact on the system's energy
production capability and are relatively costly ..
T•;nne 1 Scheme -
A scheme involving a long power tunnel could conceivably be used to replace
the De vi 1 Canyon dam in the Watana/Dev i 1 Canyon Sus i tna deve 1 opment p 1 an.
It could develop similar head for power generation at costs comparable to
the Devil Canyon dam development, and may provide some environmental advan-
tages by a voiding inundation of De vi 1 Canyon. Obviously, because of the
low winter flows in the river, a tunnel alternative could be considered
only as a second stage to the Watana development.
Conceptually, the tunnel alternatives would comprise the following major
components in some combination, in addition to the Watana darn reservoir and
associated powerhouse:
-Power tunnel intake \-Jerks.
-One or two power tunnels of up to forty feet in diameter and up to thirty
miles in length.
- A surface or underground powerhouse w·ith a capacity of up to 1200 MW.
-A re-regulation dam .if the intake works are located downstream from
Watana •
... Arrangements for compensation for loss of flow in the bypassed river
reach.
8-15
Four basic alternative schemes were developed and studied. All schemes
assume an initial Watana development with full reservoir supply level at
elevation 2200 feet and the associated powerhouse with an installed capac-
ity of 800 MW. Figure 8.7 is a schematic illustration of these schemes.
-Scheme 1: This scheme comprises a small re-regulation dam about 75 feet
high, downstream of Watana, with power tunnels leading to a second power-
house at the end of the tunnel near Devil Canyon. This power station
would operate in series with the one at Watana since the storage behind
there-regulation dam is small. Essentially, the re-regulation dam pro-
vides for constant head on the tunnel and deals with surges in operation
at Watana. The two powerhouses would operate as peaking stations result-
ing in flow and level fluctuations downstream from Devil Canyon.
-Scheme 2: This proposal also provides for peaking operation of the two
powerhouses except that the tunnel intake works are located in the Watana
reservoir. Initially, the powerhouse at Watana would have 800 MW in-
stalled capacity which would then be reduced to some 70 MW after the tun-
nels are completed. This capacity would take advantage of the required
minimum flow from the Watana reservoir. The power flow would be diverted
through the tunne 1 s to the pm'lerhouse at Devil Canyon with an i nsta 11 ed
capacity of about 1150 MW. Daily fluctuations of water level downstream
would be similar to those in Scheme 1 for peaking operations.
-Schemes 3 and 4: These schemes provide for base load operation at Devil
Canyon powerhouse and peaking at Watana. In Scheme 3, the tunnel devel-
ops only the Devil Canyon dam head and includes a 245 feet high re-
regulation dam and reservoir with the capacity to regulate diurnal fluc-
tuations due to peaking operation at Watana. The site for the re-
regulation dam was chosen by means of a map study to provide sufficient
re-regulation storage, and is located at what appears to be a suitable
dam site. In Scheme 4, the tunnel intakes are located in the Watana res-
ervoir. The Watana povJerhouse installed capacity for this scheme is 800
MW, as for the \4atana-Devil Canyon development, and is used to supply
peaking demand.
Table 8.6 lists all the pertinent technical information and Table 8.7, the
energy yields and costs associated with these four schemes.
In general, development costs are based on the same unit costs as those
used in other Susitna developments. Little geotechnical information is
available for much of the proposed tunnel routes. Nevertheless, on the
basis of precedent, tunnel construction costs are estimated on the assump-
tion that excavation will be done by conventional drill and blast opera-
tions and that the entire length may not have to be lined. Tentative as-
sumptions as to the extent of lining and support are as follows:
-31 percent unlined.
-34 percent shotcrete-lined.
-26 percent concrete-lined.
9 percent lined with steel sets and concrete.
8-16
Based on the foregoing economic information, Scheme 3 produces the lowest
cost energy.
A review of the environmental impacts associated with the four tunnel
schemes indicates that Scheme 3 would have the least impact, primarily be-
cause it offers the best opportunities for regulating daily flows down-
stream from the project. Based on this assessment, and because of its
economic advantage, Scheme 3 was selected as the most appropriate. More
detailed general arrangement drawings for this alternative were produced
(Plates 8 and 9) and casted. The capital cost estimate appears in Table
8.8. It should be noted that the cost estimates in this table differ
slightly from those in Table 8.5 and reflect the additional level of de-
tail. They also incorporate single and double tunnel options. For pur-
poses of these studies, the double tunnel option has been selected because
of its superior reliability. It should also be recognized that the cost
estimates associated with the tunnels are probably subject to more varia-
tion than those associated with the dam schemes due to geotechnical uncer-
tainties. In an attempt to compensate for these uncertainties, economic
sensitivity analyses using both higher and lower tunnel costs have been
conducted.
(c) Additional Basin Development Plan
As noted above, the Watana and High Devil Canyon dam sites appear to be in-
dividually superior in economic terms to all others. An additional plan \'las
therefore developed to assess the potential for developing these two sites
together. For this se'heme, the Watana dam would be developed to its full
potential.· However, the High Devil Canyon dam would be constructed to a
crest elevation of 1470 feet to fully utilize the head downstream from
Watana.
Costs for the lower level High Devil Canyon dam were developed Jby assuming
the same general arrangement as for the higher version shown in Plate 4 and
appropriately adjusting the quantiti~s involved.
(d) Selected Basin Development Plans
The essential objective of this step in the development selection process
is defined as the identification of those plans which appear to warrant
further, more detailed evaluation. The results of the final screening
process indicate that the Watana/Devil Canyon and the High Devi1 Canyon/Vee
plans are clearly superior to all other dam combinations. In addition, it
was decided to study further the tunnel scheme as an alternative to the
Watana/High Devil Canyon plan.
Associated with each of these plans are several options for staged develop-
ment, including staged construction of the dams and/or the power generation
facilities. For this more detailed analysis of these basic plans, a range
of different aproaches to staging the developments are considered. In
order to keep the total options to a reasonable number and also to maintain
reasonably large staging steps consistent with the total development size,
staging of only the two 1 arger deve 1 opments, i.e. Watana and High De vi 1
Canyon, is considered. The basic staging concepts·adopted for these
developments involve staging both darn and pov1erhouse construction or
alternatively just staging powerhouse construction.. Powerhouse stages are
considered in 400 MW increments.
8-17
Four basic plans are considered.
briefly described below. Plan 1
Plan 2 the High Devil Canyon-Vee
and Plan 4 the Watana-High Devil
These are summarized in Table 8.9 and are
involves the Watana-Devil Canyon sites,
sites, Plan 3 the Watana-tunnel concept
Canyon sites.
Under each plan several alternative subplans are identified, each involving
a different staging concept.
(i) Plan 1
-Subplan 1.1: The first stage involves constructing Watana dam to
its full height and installing 800 MW. Stage 2 involves construct-
ing Devil Canyon dam and installing 600 MW.
-Subplan 1.2: For this Subplan, construction of the Watana dam is
staged from a crest elevation of 2060 feet to 2225 feet. The power-
house is also staged from 400 MW to 800 MW. As for Subplan 1.1, the
final stage involves Devil Canyon with an installed capacity of 600
MW.
-Subplan 1.3: This Subplan is similar to Subplan 1.2 except that
only the powerhouse and not the dam at Watana is staged.
(ii) Plan 2
-Subplan 2.1: This Subplan involves constructing the High Devil
Canyon dam first with an installed capacity of 800 MW. The second
stage involves constructing the Vee dam with an installed capacity
of 400 MW.
-Subplan 2.2: For this Subplan, the construction of High Devil
Canyon dam is staged from a crest elevation of 1630 to 1775 feet.
The installed capacity is also staged from 400 to 800 MW. As for
Subplan 2.1, Vee follows with 400 MW of installed capacity.
-Subplan 2.3: This Subplan is similar to Subplan 2.2 except that
only the powerhouse and not the dam at High Devil Canyon is staged.
(iii) Plan 3
-Subplan 3.1: This Subplan involves initial construction of Watana
and installation of 800 MW of capacity. The next stage involves the
construction of the downstream re-regulation dam to a crest eleva-
tion of 1500 feet and a 15 mile long tunnel. A total of 300 MW
would be installed at the end of the tunnel and a further 30 MW at
the re-regulation dam. An additional 50 MW of capacity would be ·in-
stalled at the Watana powerhouse to facilitate peaking operations.
-Subplan 3.2: This Subplan is essentially the same as Subplan 3.1
except that construction of the initial 800 MW powerhouse at Watana
is staged.
8-18
?
(iv) Plan 4
This single plan was developed to evaluate the development of the two
most economic dam sites1 Watana and High Devil Canyon, jointly. Stage
1 involves constructing Watana to its full height with an installed
capacity of 400 MW. Stage 2 involves increasing the capacity at
Watana to 800 M~J. Stage 3 involves constructing High De vi 1 Canyon to
·a crest elevat·ion of 1470 feet so that the reservoir extends to just
downstream of Watana. In order to develop the full head between
Watana and Portage Creek, an additional smaller dam is added down-
stream of High Devil Canyon. This damwou1d be located just upstream
from Portage Creek so as not to interfere with the anadromous fisher-
ies and would have a crest elevation of 1030 feet and an installed ca-
pacity of 150 MW. For purposes of these studies, this site is refer-
red to as the Portage Creek site.
3.7 -fyaluation of Basin Development Plans
The overall objective of this step in the evaluation process is to select the
preferred basin development plan. A preliminary evaluation of plans was ini-
ti a 1ly undet~taken to determine broad comparisons of the avai 1 ab 1 e a 1 ternatives.
This was followed by appropriate adjustments to the plans and a more detailed
evaluation and comparison.
(a) Preliminary Evaluations
Table 8.9 lists pertinent details such as capital costs, construction per-
iods and energy yields associated with the s11~ected plans. The cost infor-
mation was obtained from the engineering layout studies described in Sec-
tion 8.4. The energy yield information was developed using a multireser-
voir computer model. This model simulates, on a monthly basis, the energy
production from a given system of reservoirs for the 30-year period for
which streamflow data is available. It incorporates daily peaking opera-
tions if these are required to generate the necessary peak capacity. A 11
the model runs incorporate preliminary environmental constraints. Seasona 1
reservoir dr·awdowns are 1 imited to 150 feet for the 1 arger and 100 feet for
the smaller reservoirs; daily drawdowns for daily peaking operations are
limited to 5 feet and minimum discharges from each reservoir are maintained
at all times to ensure all river reaches remain watered. These minimum
discharges were set approximately equal to the seasonal average natural low
flows at the drm sites.
The model is driven by an energy demand which follo\'JS a distribution cor-
responding to the seasonal distribution of the total system load as out-
lined in Section 5, Table 5.10.
The model was used to evaluate for each stage of the plans described above
the average and firm energy and the installed capacity for a specified
plant factor. This usually required a series of iterative runs to ensure
that the number of reservoir failures in the 30-year period were limited to
one year. The firm power was assumed equal to that delivered during the
second lowest annual energy yield in the simulation period. This corres-
ponds approximately to the 95 percent level of assurance.
A more detailed description of the model, the model runs, and the average
monthly energy yields associated with the development plans is given in
Appendix F.
8-19
A range of sensitivity runs was conducted to explore the effect of the res-
ervoir drawdown limita1:ion on the energy yield. The results of these runs
are summarized in Table 8.10. They indicate that the drawdown limitations
currently imposed reduce the firm energy yield for Watana development by
approximately 6 percent.
(b) Plan Modifications
In the process of evaluating the schemes, it became apparent that there
would be environmental problems associated with allowing daily peaking op-
erations from the most downstream reservoir in each of the plans described
above. In order to avoid these potential problems while still maintaining
operational flexibility to peak on a daily basis, re-regulation facilities
were incorporated in the four basic plans.. These facilities incorporate
both structural measures such as re-regulation dams and modified operation-
al procedures. Details of these modified plans, referred to as El to E4,
~re listed in Table 8.11.
A brief description of the changes that were made follows:
{i} El Plans
For Subplans 1.1 to 1.3 a low temporary re-regulation dam is con-
structed downstream from Watana during the stage in which the generat-
ing capacity is increased to BOO MW. This dam would re-regulate the
outflows from Watana and allow daily peaking operations. It has been
assumed that it would be possible to incorporate this dam with the di-
version~ works at the Devil Canyon site, and an allowance of $100
million has been made to cover any additional costs associated with
this approach.
In the final stage, only 400 MW of capacity is apded to the dam at
Devil Canyon instead of the original 600.MW. Reservoir operating
rules are changed so that Devil Canyon dam acts as the re-regulation
dam for Watana.
(ii) E2 Plans
For Subplans 2.1 to 2.3 a permanent re-regu1ation dam is located down-
stream from the High Devil Canyon site at the same time the generating
capacity is increased to 800 MW. An allowance of $140 million has
been made to cover the costs of such a dam ..
An additional Subplan E2.4 was established. This plan is similar to
E2.3 except that the re-regulation dam is utilized for power produc-
tion. The dam site is located at the Portage Creek site with a crest
level set so as to utilize the full head. A 150 MW powerhouse is in-
stalled. As this dam is to serve as are-regulating facility, it is
constructed at the same time as the capacity of High Devil Canyon is
increased to 800 MW, i.e. during Stage 2.
( i i i ) E3 P 1 an
The Watana tunnel develoyment plan already incorporates an adequate
degree of re-regulation and the E3.1 plan is~ therefore, identical to
to the 3.1 plan.
8-20
{iv) E4 Plans
As for the El Plans, the E4.1 plan incorporates are-regulation dam
downstream from Watana during Stage 2. As for the El plans, it has
been assumed that it would be possibl_e to i.ncorporate this dam as part
of the diversion arrangements at the High Devi 1 Canyon site, and an
allowance of $100 million has been made to cover the costs ..
The energy and cost information presented in Tabl1~ 8.11 is graphically
displayed in Figure 8,.8 which shows plots of average annual energy
production versus total capital costs for all the plans. Although
these curves do not represent accurate economic analyses, they do give
an indication of the relative economics of the schemes. These evalua-
tions basically reinforce the results of the screening model; for a·
total energy production capability of up to approximately 4000 Gwh,
Plan E2 (High De vi 1 Canyon) provides the most economic energy whi 1 e
for capabilities in the range of 6000 Gwh, Plan El {vJatana-Devil
Canyon) is the most economic.
The plans listed in Table 8oll are subjected to a ~ore detailed analy-
sis in the following section.
(c) Evaluation Criteria and Methodology
The approach to evaluating the various basin development plans described
above is twofold:
-For determining the optimum staging concept associated with each basic
plan (i.(. the optimum subplan) economic criteria only are used and the
1 east cost staging concept is adopted.
-For assessing which plan is the most appropriate, a more detailed e\h'~lua
tion process incorporating economic, environmental, social, and ener·gy
contribution aspects are taken into account . 3
Economic evaluation of any Susitna Basin development plan requires that the
impact of th~ plan on the cost of energy to the railbelt area consumer be
assessed on a systemwide basis. As the consuliler is supplied by a large
number of different generating sources, it is necessary to determine the
total Railbelt system cost in each case to compare the various Susitna
Basin development options. The basic tool used to determine the system
costs is a cc..rnputer simulation/ planning model (called OGP5) of the entire
generating system. Input to this model includes the following:
-Load forecast over a specified period of time (as conta ·i ned in Section 5,
Table 5.10).
-Load duration curves (as outlfned in Section 5.5).
-Details of the existing generating system (Section 6.2).
-A list of all potential future thermal generating· sources with associated
annualized costs, installed capacities, fuel consumption rates, etc .. (as
outlined in Section 6.5)¢
8-21
-Fuel prices (as outlined in Section 6.5).
-A specified hydroelectric development plan, i.e. the annualized costs,
on-line dates, installed capacities, and energy production capability of
the various stages of the plan (as outlined in Sections 6.4 and 8.5).
-System reliability criteria. For current study purposes, a loss of load
probability, (LOLP) of .1 day /year is used.
Utilizing the above information, the program simulates the performance of
the system, incorporates the hydroelectric development as specified, and
adds thermal generating resources as necessary to meet the load grovlth and
to satisfy the reliability criteria. The thermal plants are selected so
that the present worth of the total generation cost is minimized.
A summary of the input data to the model and a discussion of the results
follows. A more detailed description of the model r-uns is presented in
Appendix G.
As discussed in Section 1.4, the basic economic an~lyses undertaken in this
study incorporate "real 11 discount and escalation rates. The parameters
used are summarized in Table 8.12. The econor.ric lives 1isted in this table
are the same as the assumed economic lives outltned in Section 6.2.
{d) Initial Economic Analyses
s
Table 8.13 lists the results of the first series of economic analyses un-
dertaken for the basic Susitna Basin development plans listed in Table
8.11. The information in Table 8.13 includes the specified on-line dates
for the various stages of the plans, the OGP5 run index number, the total
i nsta11ed capacity at the year 2010 by category, and the total system pre-
sent worth cost in 1980. The present worth cost is evaluated for the
period 1980 to 2040~ i.e. 60 years. The OGP5 model is run for the period
1980-2010; thereafter steady state conditions are assumed and the genera-
tion mix and annual costs of 2010 are applied to the years 2011 to 2040.
This extended period of time is necessary to ensure that the hydroelectric
options being studied, many of which only come on-line around 2000, are
operated for periods approaching their economic lives and that their full
impact on the cost of the generation system are taken into account.
The highlights of the results in Table 8.13 can be summarized as follows:
( i) Plan E 1 ... Watana-Devi 1 Canyon
Staging the dam at Watana (Plan E1. 2) is not as economic as con-.
structing it to its full height (Plans El.l and E1.3). The economic
advantage of not staging the dam amounts to $180 million in 1980.
-The results indicate that to the level of analysis performed, there
is no discernible benefit in staging constructi'on of the Watana
powerhouse (Platts El.l and E1.3). It is considered likely, however,
that some degree of staged pm·1erhouse construction wi 11 ultimately
be incorporated due to economic considerations and also because it
8-22
( i i )
provides maximum flexibility. For current planning purposes, it is
therefore assumed that the staged powerhouse concept, i.e Plan El.3,
is the most appropriate ~~atana-Devi 1 Canyon deve 1 opment p 1 an.
Additional runs performed for variations of Plan El.3 indicate that
system costs would increase by $1,110 million if the Devil Canyon
dam stage were not constructed. Furthermore, a five year delay in
construction of the Watana dam would increase system costs by $220
million. These increases are due to additional higher cost thermal
units which must be brought on line to meet the forecast demand in
the early 1990's.
-Plan El. 4 indicates that sho.ui d the powerhouse size at Watana be
restricted to 400 MW the overall system cost would increase by $40
million.
Plan E2 -High De vi 1 Canyon-Vee
I
-Plans E2.1 and E2.2 were not analyzed as these are similar to El.l
and E1.2 and similar results can be expected.
·-The results for Plan E2.3 indicate it is $520 million more costly
than Plan E1.3. Cost increases also occur if the Vee dam stage is
not constructed. A cost reduction of approximately $160 million is
possible if the Chakachamna hydroelectric project is constructed
instead of the Vee dam. ·
-The results of Plan E2.5 indicate that total system generating costs
would go up by $160 million if the total capacity at High Devil
Canyon \tiere 1 imited to 400 MW.
(iii) Plan E3
The results for Plan E3.1 illustrate that the tunnel scheme versus the
Devil Canyon dam scheme (E1.3) adds approximately $680 million to the
total system cost. The availability of reliable geotechnical data
would undoubtedly have improved the accuracy of the cost estimates for
the tunnel alternative. For this r•eason, a sensitivity analysis was
made as a check to determine the effect of halving the tunnel costs.
This analysis indicates that the tunnel scheme is still more costly by
$380 million.
(iv) Plan E4
The results indicate that system costs associated with Plan E4.1 ex-
cluding the Portage Creek site development are $200 million more than
the equivalent El plan. If the Portage Creek development is included,
a greater increase in cost would result.
(e) Economic Sensitivity Analyses
Plans El, E2, and E3 were subjected to further sensitivity analyses to
assess the economic impacts of various loadgrowths. These results are
summarized-in Table 8.14.
8-23
The results for low load forecasts illustrate that the most viable Susitna
Basin development plans include the 800 MW plansji i .. e. Plan EL.5 and E2.5.
Of these two, the Watana-Devil Canyon plan is less costly than the High
Devil Canyon-Vee plan by $210 million. Higher system costs are involved if
only the first stage dam is constructed, iee. either Watana or High Devil
Canyon. In this cas·e, the Watana only plan is $90 million more costly than
the High Devil Canyon plan ..
Plan E3 variations are more costly than both Plans El and £2.
For the high load forecasts, the results indicate that the Plan E1.3 is
$1040 million less costly than E2.3. The costs of both plans can be
reduced by $630 and $680 million respectively by the addition of the
Chakachamna development as a fourth stage.
No further analyses were conducted on Plan. £4., As envisaged, this plan is
similar to Plan E1 with the exception that the lower main dam site is moved
from Devil Canyon upstream to High Devil Canyon. The initial analyses out-
lined in Table 8.13 indicate this scheme to be more expensive.
(f) Evaluation Criteria
As outlined in the generic methodology (Section 1.4 and Appendix A), the
final evaluation of the development plans is to be undertaken by a per-
ceived comparision process on the basis of appropriate criteria. The fol-
lowing criteria are used to evaluate the shortlisted basin development
plans. They generally contain the requirements of the generic process with
the exception that an additional criterion, energy contribution, is added.
The. objective of including this criterion is to ensure that fuli considera-
tion is given to the -total basin energy potential that is developed by the
various plans ..
(i) Economic:
The parameter used is the total present worth cost of the total Rail-
belt generating system for the period 1980 to 2040 as listed in
Tables 8.14 and 8.15.
{ii) Environmental:
A qualitative assessment of the environmental impact on the
ecological~ cultural~ and aesthetic resources is undertaken for each
plan. Emphasis is placed on identifying major concerns so that these
could be combined with the other evaluation attributes in an overall
assessment of the plan.
(iii) Social:
This attribute includes determination of the potential non-renewable
resource displacement, the impact on the state and local economv, and
the r·isks and consequences of major structural failures due to seis-
mic events. Impacts on the econonw refer to the effects of an invest-
ment plan on economic variables.
8-24
{iv) Energy Contribution:
The parameter used is the total amount of energy produced from the
specific development plan. An assessment of the energy development
foregone is also undertaken. This energy loss is inherent to the
plan and cannot easily be recovered by subsequent staged develop-
ments.
(g) Results of Evaluation Process
The various attributes outlined above have been determined for each plan
and are summarized in Tables 8 .. 16 through 8.24. Some of the attributes are
quantitative while others are qualitative. Overall evaluation is based on
a comparison of similar types of attributes for each plan. In cases where
the attributes associated with one plan all indicate equality or superior-
ity with respect to another plan, the decision as to the best plan is clear
cut. ln other cases where some attributes indicate superiority and others
inferiority, these differences are highlighted and trade-off decisions are
made to determine the preferred development plan •. In cases where these
trade-offs have had to be made, they are relatively convincing and the
decision making process can, therefore, be regarded as fairly robust. In
addition, these trade-offs are clearly identified so the recorder can inde-
pendently answer the jt~dgement decisions made.
The overall evaluation process is conducted in a series of steps. At each
step, only a pair of plans is evaluated. The superior plan is then passed
on to the next step for evaluation against an alternative plan.
( i) De vi 1 Canyon Dam Versus Tunne 1
The first step in the process i nvo 1 ves the eva 1 uat ion of the Watana-
Devil Canyon dam plan {El.3) and the Watana tunnel plan (E3.1). As
Watana is common to both plans, the evaluation is based on a compari-
son of the Devil Canyon dam and tunnel schemes.
In order to assist in the evaluation in terms of economic criteria~
additional information obtained by analyzing the results of the OGPS
computer runs is shown in Table 8.16. This information illustrates
the breakdown of the total system present worth cost in terms of capi-
tal investment, fuel and operation and maintenance costs.
-Economic Comparison 0
From an economic point of view, the Devil Canyon dam scheme is su-
perior. As surrmarized in Tables 8.16 and 8.17, on a presen~ worth
basis, the tunnel scheme is $680 mill ion or about 12 percent more
expensive than the dam scheme. For a low demand growth rate~ this
cost difference would be reduced slightly to $610 million. Even if
the tunnel scheme costs are halved, the tota1 cost difference would
still amount to $380 million. As highlighted in Table 8.17, con-
sideration of the sensitivity of the basic economic evaluation to
potential changes in capital cost estimate, the period of economic
analysis, the discount rate, fuel costs, fuel cost escalation, and
economic plant lives do not change the basic economic superiority
of the dam scheme over the·tunnel scheme.
8-25
-Environmental Comparison
The environmental comparison of the two schemes is summarized in
Table 8.18. Overall~ the tunnel scheme is judged to be superior
because:
o It offers the potential for enhancing anadromous fish popula-
tions downstream of the re-regulation dam due to the more
uniform flow distribution that will be achieved in this reach;
-o It inundates 13 miles less of resident fisheries habitat in
river and major tr.ibutari es;
o It has a lower impact on wildlife habitat due to the smaller in-
undation of habitat by the re-regulation dam;
o It has a lower potential for inundating archeologicc-1 sites due
to the smaller reservoir involved;
o It would preserve much of the characteristics of the Devil Can-
yon gorge which is considered to be an aesthetic and recrea-
tional resource.
-Social Comparison
Table 8.19 summarizes the evaluation in terms of the social cri-
teria of the two schemes. In terms of impact on state and local
economics and risks due to seismic exposure, the two schemes are
rated equallyo However, the dam scheme has, due to its higher
energy yield, more potential for displacing nonrenewable energy
resources, and therefore scores a slight overall plus in terms of
the social evaluation criteria.
-Energy Comparison
Table 8.20 summarizes the evaluation in terms of the energsy con-
tribution criteria. The results shown that the dam scheme has a
greater potential for energy production and develops a larger
portion of the basin's potential. The dam scheme is therefore
judged to be superior from the energy contribution standpoint.
-Overall Comparison
The overall evaluation of the two schemes is summarized in Table
8.21. The estimated cost saving of $680 million in favor of the
dam scheme is considered to outweigh.the reduction in the overall
environmental impact of the tunnel scheme. The dam scheme is
therefore judged to be superior overall.
(ii) Watana-Devil Canyon Versus High Devil Canyon-Vee
The second step in the development selection process involves an eval-
uation of the Watana-Devil Canyon (E1.3} and the High Devil Canyon-Vee
(E2.3) development plans.
8-26
-Economic .Cornpari son
In terms of the economic criteria (see Tables 8.16 and 8.17) the
Wata·na-Devil Canyon plan is less costly by $520 million. As for
the dam-tunnel evaluation discussed above~ consideration of the
sensitivity of this decision to potential changes in the various
parameters considered (i.e. load forecast, discount rates, etc.)
does not change the basic superiority of the Watana-Devil Canyon
Plan ..
-Environmental Comparison
The evaluation in terms of the environmental criteria is summarized
in Table 8.22. In assessing these plans, a reach by reach compari-
son is made for the section of the Susitna River between Portage
Creek and the Tyone River. The Watana -Devi 1 Canyon scheme wou 1 d
create more potential environmental impacts in the ~Jatana Creek
area. However, it is judged that the potential environmental im-
pacts which would occur in the upper reaches of the river with a
High Devil Canyon-Vee development are more severe in comparison
overall.
From a fisheries perspective, both schemes would have a similar
effect on the downstream anadromous fisheries although the High
Devil Canyon-Vee scheme would produce a slightly greater impact on
the resident fisheries in the Upper Susitna Basin.
The High Devil Canyon-Vee scheme would inundate approximately 14
percent (15 miles) more critical winter river bottom moose habitat
than the Watana-Devil Canyon scheme. The High Devil Canyon-Vee
scheme would inundate a large area upstream of the Vee site util-
ized by three subpopulation of moose that range in the northeast
section of the basin. The Watana-Devil Canyon scheme \'JOuld avoid
the potential impacts on moose in the upper section of the river;
however, a larger percentage of the Watana Creek basin would be
inundated.
The condition of the subpopulation of moose utilizing this Watana
Creek Basin and the quality of the habita~ appears to be decreas-
ing. Habitat manipulation measures could be implemented in this
area to improve the moose habitat. Nevertheless, it is considored
that the upstream moose habitat losses associated \'lith the High
Devil Canyon-Vee scheme \tiOUld probably be greater than the Watdna
Creek losses associated \'lith the Watana-IJevil Canyon scheme ..
A major factor to be considered in comparing the two development
plans is the potential effects on caribou in the region. It is
judged that the increased length of river flooded~ especially up-
stream from the Vee dam site, would result in the High Devil
Canyon-Vee plan creating a greater potential diversion of the
Nelchina herd's range. In addition, a larger area of caribou range
would be directly inundated by the Vee reservoir.,
8-27
The area flooded by the Vee reservoir is also considered important
to some key furbearers, particularly red fox. In a comparison of
this area with the Watana Creek area that would be inundated with
the Watana-Devil Canyon scheme, the area upstream of Vee is judged
to be more important for furbearers.
As previously mentioned, the area between Devil Canyon and the
Oshetna River or. the Susitna River is confined to a relatively
steep river valley. Along these valley slopes are habitats
important to birds and black bears. As the Watana reservoir would
flood the ri v.er section between the Watana Dam site and the Oshetna
River to a higher elevation than would the High Devil Canyon
reservoir {2200 feet as compared to 1750 feet) the High Devil
Canyon-Vee plan would retain the integrity of more of this river
valley slope habitat.
From the archeolooical studies done to date, there tends to be an -. increase in site intensity as one progresses towards the northeast
section of the Upper Susitna Basin.-The High Devil Canyon-Vee plan
would result in more extensive inundation and increased access to
the northeasterly section of the basin. This plan is therefore
judged to have a gr~ater potential for diract1y 0r indirectly
affecting archeological sites.
Due to the wilderness nature of the Upper Susitna Basin, the crea-
tion of increased access associated with project development could
have a significant influence on future uses and management of the
area. The High Devil Canyon-Vee plan would involve the construc-
tion of a dam at the Vee site an~ the creation of a reservoir in
the more northeasterly section of the basin. This plan would thus
create inherent access to more wilderness than would the Watana-
Devil Canyon scheme. As it is easier to extend access than to
limit it, inherent access requirements are considered detrimental
and the Watana-Devil Canyon scheme is judged to be more acceptable
in this regard.
Except for the increased loss of river valley, bird, and black bear
habitat the Watana-Devil Canyon development plan is judged to be
more environmentally acceptab 1 e than the High De vi 1 Canyon-Vee
plan. Although the Watana-Devil Canyon plan is considered to be
the more environmentally compatible Upper Susitna development plan,
the actual degree of acceptability i_s a question being addressed as
part of ongoing studies.
-Energy Comparison
The evaluation of the t\'IO p1ans in terms of energy contribution
criteria is sumnarized in Table 8.23. The Watana-Devil Canyon
scheme is assessed to be superior due to its higher energy poten-
tial and the fact that it develops a higher proportion of the
basin 1 s potential.
8-28
-----------~-----~-
-Social Comparison
Tab.le 8.19 summarizes the evaluation in terms of the social criter-
ia. As in the case of the dam versus tunnel comparison.,, the
Watana-Devil Canyon plan is judged to have a slight advantage over
the High Devil Canyon-Vee plan. This is because of its greater po-
tential for displacing nonrenewable resources.
-Overall Comparison
The overall evaluation is summarized in Table 8 .. 24 and indicates
that the Watana-Devil Canyon plans are generally superior for all
the evaluation criteria~ '
(iii) Preferred Susitna Basin Development Plan
Comparisons of the Watana-Devil Canyon plan with the Watana-tunnel
plan and the High Devil Canyon-Vee plans are judged to favor ·the
Watana-Devil Canyon plan in each case.
The Watana·-Devi 1 Canyon p 1 an is therefore se 1 ected as the preferred
Susitna Basin development plan, as a basis for continuation of more
detailed design optimization and environmental studies ..
8.8 -Comparison of Generation Scenarios With and
Without the Susitna Basin Development Plan
This secti·on outlines the results of the preliminary studies undertaken to com-
pare the~preferred Railbelt generation scenario incorporating the selected
Watana-Devil Canyon dam development plan, with alternative generation scenarios.
These studies are not intended to develop comprehens~ve and detailed alternative
generating scenarios but merely to obtain a preliminary assessment of the feasi-
bility of the Sus"'tna plan in terms of economic, environmental, and social cri-
teria.
The main alternative generating scenar·io considered is the all-thermal cption,
and a detailed evaluation of the 11 ~'/ith Susitna 11 and the all-thermal generation
scenarios is carried out. In addition to this, a less detailed assessment of
the generating scenarios incorporating non-Susitna Basin hydro development is
also conducted. The objective of the latter evaluation is to assess the econom-
i cs of deve 1 oping a 1 ter·nat i ve and generally sma 11 er hydro projects. A more com-
prehensive comparison would require more detailed analyses of the environmental
and technical aspects at each of the sites which are not being undertaken under
the current studies.
(a) 11 Without Susitna" Generation Scenarios
The developnent and· evaluation of Railbelt generation plans incorporating
all-thermal and thermal plus non-Susitna hydroelectric alternatives, is
discussed in Section 6. Results of all-thermal and thermal with Susitna
alternatives are given in Table 6•4·
8-29
(b) Comparison of All-Thermal and
,.
uWith Susitnan Generation Scenarios
(i) Economic Comparison
In terms of economic criteria~ the 11 WithSusitna" scenario is $2280
million less costly than the all-thermal option. In order to explore
the sensitivity of this comparison in more detail, several additional
runs were carried out with the OGP5 model. For these runs~ parameters
such as projected load growth!} interest rates, fuel costs and
escalation rates-economic lives, and capital costs were varied and
the impact on the overall system costs assessed. The detailed results
are presented in Table 8.25 and are summarized in Table 8.26. A brief
outline of these results follows.
The economic advantage of the '1with Susitna" scenario decreases with
decreasing load grm>~th but still amounts to $1280 million for the very
low forecast. A lmver limit thermal plant capital cost estimate was
also considered. The cost estimate was based on the minimum Aluska
cost factor adjustment reported in the literature rather than the
average factor used for the standard cost estimates which appear in
Table 6.4o Even though this results in a 72 percent reduction in the
thermal capital cost~ the "with Susitna" scenario is still $1850
million more economice The second type of capital cost sensitivity
run involved increasing the Susitna Basin hydro development cost by 50
percent to represent an extreme upper limit. Even with this cost ad-
justment, the "with Susitna" generating scenario costs are still less
than the a 11-therma 1 scenario by $1320 mi 11 ion •
.
As shown in Table 8.26, shortening the period of economic analysis
from 60 to 30 years (i.e. to 1980-2010) reduces the net benefit to
$960 million. The int-erest rate sensitivity run results indicate that
the 11 With Susitna" scenario is more economic for real interest rates
of zero to eight percent. At rates above this, the thermal scenario
becomes more economic. A fuel cost sensitivity run using an assumed
20 percent reduction to the estimated cost of fuel reduces the cost
difference to $1810 million.
Fuel cost escalation is an important parameter and the sensitivity
analyses show that for zero percent escalation on all fuels the dif-
ference in total system costs reduces to $200 million. A zero percent
escalation rate for coal-only reduces this difference to $1330
million.
The final sensitivity runs assumed the economic lives of all-thermal
units is extended by 50 percent. This reduces the cost difference to
$1800 mi 11 ion.
The above results indicate that the "with Susitna" scenario remains
the more economic plan for a wide range of parameters. At real inter-
est rates exceeding 8 percent, the all-thermal option becomes more
attractive. It is, however, unlikely that such high rates would ever
materialize. Although .the net economic advantage of the 11 With
Susitna" scenario is significantly reduced, a zero fuel cost
escalation rate still results in a more expensive a11-therm~1
generation scenario.
8-30
(ii) Social Comparison
The evaluation in terms of social criteria is summarized in Table
8.27. The "with Susitna" scenario provides greater potential for
non-renewable resource conservation and is, therefore, regarded as
superior from this point of view.
There is insufficient information available at this time to fully
evaluate the impact on the state and local economics. The pattern of
power investment expenditures will probably tend to be more regular
with the all-thermal plan and hence there is potentially a more.grad~
ual impact than with the Susitna-inclusive generation plan. The
timing of the Susitna type investment ts probably more disruptive in
relation to other large scale Alaskan projects. However, this could
result in counter-cyclical investment that would tend to reduce such
disruptions. ·
(iii} Environmental Comparison
Table 8.28 broadly summarizes the environmental impacts associated
with the two scenarios. As indicated, both hydro and thermal devel-
opment have potential for environmental impact. However, the extent
to which the potential impacts are realized is very site specific.
As specific information on potential future coal-fired generating
sources is not available at this time, the overall comparison is
generic rather than site specific.
(iv) Overall Comparison
An overall evaluation is summarized· in Table 8e29. This indicates
that the uwith Susitna" scenario is clearly superior with regard to
the economic criteria and suggests that there is not a distinguish-
able difference between the evaluations based on environmental and
social criteria. It is therefore concluded that the scenario incor-
porating the Watana-Devil Canyon plan is superior to the all-thermal
scenario.
(c) Comparison of the "With Susitna" and
Alternative Hydro Generating Scenarios
Comparison of the 11 With-Susitna 11 and alternative hydro Rai1belt generation
scenarios have been made only on the basis of economics. Although prelimi-
nary screening of the ~:lternative hydroelectri~ developments is made as
described in Section 6, the absence of immediate site-specific data pre-
vents a more detailed assessment of non-economic aspects.
The 11 with-Susitnau scenario is generally $1190 million more economic than
the scenario incorporating the alternative hydro developments. Although
development of the Susitna Basin is more economic than developing alterna-
tive hydro, this does not imply that alternative hydro should be neglected.
In fact, as several of the combination runs involving both Susitna and non-
Susitna hyd~~o alternatives indicate, it may be economically advantageous to
consider development of several alternative hydro sites in conjunction with
Susitna.
8-3·i
TABLE 8.1 -POTENTIAL HYDROELECTRIC DEVELOPMENT
Average Economic 1
Dam Capital Installed Annual Cost of Source
Proposed Height Upstream Cost Caj:?acity Energy Energy of
Site Type Ft. Regulation $ million (MW) Gwh $/1000 kWh Data
Gold Creek2 Fill 19~ Yes 9~0 260 1,140 37 USBR 1953
Olson
( Susitna I I) Concrete 160 Yes 600 200 915 31 USBR 1953
KAISER 1974
CDE 1975
Devil Canyon Concrete 675 No B30 250 1,420 27 This Study
Yes 1,000 600 2,9BO 17 "
High Devil Canyon " (Susitna I) Fill B55 No 1,500 BOO 3,540 21 "
Devil Creek 2 Fill Approx No
B50
co Watana Fill BB~ No 1,B60 BOO 3,250 2B " I w
N Susitna III Fill 670 No 1 '390 350 1 ,5BO 41 "
Vee Fill 610 No 1,060 400 1' 3 71l 37 "
t4aclaren 2 Fill 1B5 No 5304 55 1BO 124 "
Denali Fill 230 No 4B~4 60 245 B1 "
Butte Creek2 Fill Approx No 40 1303 USBR 1953
150
Tyone 2 Fill Approx
60
No 6 22 3 USBR 1953
~:
(1)Includes AFDC, Insurance, Amortization, and Operation & Maintenance Costs.
(2)No detailed engineering or energy studies undertaken as part of this study.
(3)These are approximate estimates and serve only to represent the potential of
(4)Include estimated costs of power generation facility.
these two dam sites in perspective.
TABLE B.2 -COST COMPARISONS
Ca!;!ital Cost Estimate2 (19BO $)
D A M ~ r R E ~ ~~~!] o 1 R t R ~
Installed Caplfal Cos£ lnsta [led CapJ.tal Cost Source and
Site Type Capacity -MW $ million Capacity -MW $ million Date of Data
Gold Creek Fi l1 260 1 B90 USRB 196B
Olson
1901 (Susitna I I) Concrete 550 COE 1975
Devil Canyon Fill 600 1 ,ooo
Concrete
Arch 776 63D COE 1975
Concrete
Gravity 776 910 COE 197B
High Devil Canyon
(Susitna I)
Fill BOO 1,500 700' 1 ,4BO COE 1975
00 Devil Creek Fi l1 I w w Watana Fill BOO 1,B60 792 1,630 COE 197B
Susitna [[[ Fi l1 350 1,390 445 KAISER 1974
Vee Fill 400 1,060 770 COE 1975
Maclaren Fill 55 530
Denali Fill 60 4BO None 500 COE 1975
Notes:
(1) Dependable Capacity
(2) Excluding Anchorag8/Fairbanks transmission intertie, but including local access and transmission.
TABLE 8.3 -DAM CREST AND FULL SUPPLY LEVELS
Staged Full bam Average Dam
Dam Supply Crest Tailwater Height 1
Site Construction Level -Ft. level -Ft. Level -ft. ft.
Gold Creek No 870 880 680 290
Olson No 1,020 1,030 810 310
Portage Creek No 1,020 1,030 870 250
Devil Canyon-
intermediate
height No 1,250 1,270 890 465
Devil Canyon -
full height No 1,450 1,470 890 675
High Devil Canyon No 1,610 1,630 1,030 710
No 1,750 1,775 1,030 855
Watana Yes 2,000 2,060 1,465 680
Stage 2 2,2011 2,225 1,465 880
Susitna III No 2,340 2,360 1,810 670
Vee No 2,330 2, 350 1,925 610
Maclaren No 2,395 2,405 2,300 185
Denali No 2,540 2,555 2,405 230
Notes:
(1) To foundation level.
8-34
TABLE 8.4 -CAPITAL COST ESTIMATE SUMMARIES
SUSITNA BASIN DAM SCHEMES
COST IN $MILLION 1980
Devd Canyon High Dev1l Canyon Watana Sus1fna I I 1 Vee Maclaren lknah
1470 ft Crest 1775 ft Crest 2225 ft Crest 2360 ft Crest 2350 ft Crest 2405 ft Crest 2250 ft Crest
Item 600 MW 800 MW 800 MW 330 MW 400 MW No ~ower No eower
1 ) Lands, Damages & Reservoirs 26 11 46 13 22 25 38
2) Diversion Works 50 48 71 88 37 11B 112
3) Main Dam 166 432 536 398 183 106 100
4) Auxiliary Dam 0 0 0 0 40 0 0
5) Power System 195 232 244 140 175 0 0
6) Spillway System 130 141 165 121 74 0 0
7) Roads and Bridges 45 68 96 70 80 57 14
ro 8) Transmission Line 10 10 26 40 49 0 0
I w 9) Carrp Facilities and Support 97 140 160 130 100 53 50 U"l
10) Miscellaneous 1 8 8 8 8 8 5 5
11 ) Mobi.lization and PreE.aration 30 47 57 45 35 15 14
Subtotal 757 1137 1409 1053 803 379 333
Contingency (20%) 152 227 282 211 161 76 67
Engineering and Owner's
Administration (12%) 91 136 169 126 96 45 40
TOTAL 1000 1500 1860 1390 1060 500 440
Notes:
(1) Includes recreational facilities, buildings and grounds and permanent operating equipment.
TABLE B.5 -RESULTS OF SCREENING MODEL
Total Demand First Second
o a
Cap. Energy Site Site Cost Site
Run MW GWh Names Names $ million Names
1 400 1750 High 15BO 400 BB5 Devil 1450 400 970 Watana 1950 400 9BO
Devil Canyon
Canyon
2 BOO 3500 High
Devil
1750 BOO 1500 Watana 1900 450 1130 Watana 2200 BOO 1B60
Canyon
Devil
Canyon 1250 350 710
TOTAL BOO 1B40
co
I 3 1200 5250 Watana 2110 700 1690 High 1750 BOO 1500 High 1750 820 1500 w
0"> Devil Devil
Canyon Canyon
Devil 1350 500 BOO Vee 2350 400 1060 Susitna 2300 3BO 1260
Canyon Ill
TOTAL 1200 2490 TOTAL 1200 2560 TOTAL 1200 2760
4 1400 6150 Watana 2150 740 1770
N 0 S 0 L U T I 0 N N 0 S 0 L U T I 0 N
Devil 1450 660 1000
Canyon
TABLE 8.6 -INFORMATION ON THE DEVIL CANYON DAM AND TUNNEL SCHEMES
Dev i 1 Canyon Tunnel Scfieme
Item Oam
Reservoir Area
(Acres) 1,sno 320 0 3,900 n
River Miles
Flooded 31.6 2.0 0 15.8 n
Tunnel length
(Miles) 0 27 29 13.5 2.9
Tunnel Vslume
( 1000 Yd ) 0 11,976 12,863 3,732 5, 1"51
Compensating Flow
Release from soo 1 Watana (cfs) 0 1,000 1t000 1,000
Downstream 2
Reservoir Volume
(1000 Acre-feet} 1,100 9.5 350
Downstream Dam
Height (feet)' 625 75 245
Typical Daily
Range of Discharge
From Devil ~anyon 6,000 4,000 4,000 8,3011 1,900
Powerhouse to to to to to
(cfs) 13,000 14,000 14,000 8,900 4,2'l0
App-roximate
Max.imum Daily
Fluctuations in
Downstream
Reservoir (feet) 2 15 4
Notes:
i 1, 000 cfs compensating flow release from the re-regu1 ation dam.
Downstream from Watana~
3 Estimated, above existing rock elevation~
8-37
00
I w
00
TABLE B.7-DEVIL CANYON TUNNEL SCHEMES
COSTS, POWER OUTPUT AND AVERAGE ANNUAL ENERGY
Stage
STAGE 1 :
Watana Dam
STAGE 2:
Tunnel:
-Scheme 1
-Scheme 22 -Scheme 3
-Scheme 4
~:
Watana Dev1l Canyon
BOO
BOO
70
B50
BOO
Tunnel
550
1,150
330
365
Increase 1 in
Installed Capacity
(MW)
550
42D
3BO
365
Devil Canyon
Average Annual
Energy
(Gwh)
2,050
4,750
2,240
2,490
(1) Increase over single Watana, BOO MW development 3250 Gwh/yr
(2) Includes power and energy produced at re-regulation dam
(3) Energy cost is baSed on an economic analysis (i.e. using 3 percent interest rate)
Increase 1 in
Average
Annual Energy
(Gwh)
2,050
1,900
2,1BO
B90
Tunnel Scheme
Total Project
Costs
$ Million
19BO
2320
1220
1490
3 Cost of
Additionyl
Energy
(mills/kWh)
42.6
52.9
24.9
73.6
TABLE 8.8 -CAPITAL COST ESTIMATE SUMMARIES
TUNNEL SCHEMES
COSTS IN $MILLION 1980
Item
Land and damages, reservoir clearing
Diversion works
Re-regu lation dam
Power system
(a) Main tunnels
(b) Intake, powerhouse, tailrace
and switchyard
Secondary power station
Spillway system
Roads and bridges
Transmission lines
Camp facilities and support
Miscellaneous*
Mobilization and preparation
TOTAL CONSTRUCTION COST
Contingencies (20%)
Engineering, and Dwner 1 s Administration
TOTAL PROJECT COST
8-39
557
123
wo
dia tunnels
14
35
102
680
21
42
42
15
131
8
47
1,137
227
136
1,500
453
123
14
35
102
576
21
42
42
15
117
8
47
1,015
203
122
1,340
TABLE 8.9. SUS!TNA DEVELOPMENT PLANS
Cumulative
Stage/Incremental Data System Data
Annual
Maximum Energy
Capital Cost Earliest Reservoir Seasonal Production Plant
$ Millions On-line Full Supply Draw-Firm Avg. Factor
Stage ( 1980 values) 1 GWH. ~ Plan Construction Date Leve 1 -ft. down-ft GWH •
1.1 1 Watana 2225 ft 800MW 1860 1993 2200 150 2670 3250 46
2 Devil Canyon 1470 ft
600 MW 1000 1996 1450 100 5500 6230 51
TOTAL SYSTEM 1400 MW 2ii6o
00
I
""" 0 1. 2 1 Watana 2060 ft 400 MW 1570 1992 2000 100 1710 2110 60
2 Watana raise to
2225 ft 360 1995 2200 150 2670 2990 85
3 Watana add 400 MW
capacity 130 2 1995 2200 150 2670 3250 46
4 Devil Canyon 1470 ft
600 MW 1000 1996 1450 100 5500 6230 51
TOTAL SYSTEM 1400 HW 3060
1.3 1 Watana 2225 ft 400 MW 1740 1993 2200 150 2670 2990 85
2 Watana add 400 MW
capacity 150 1993 2200 150 2670 3250 46
3 Devil Canyon 1470 ft
600 MW 1000 1996 1450 100 5500 6230 51
TOTAL SYSTEM 1400 MW 2890
TABLE 8.9 (Continued)
Cumulative
Stage/Incremental Data System Data
Annual
Maximum Energy
Capital Cost Earliest Reservoir Seasonal Production Plant
$ Millions On-line Full Supply Draw-Firm Avg. Factor
(1980 values) 1 ~ Plan Stage Construction Date Level -ft. down-ft. GWH GWH •
2.1 High Devil Canyon
1775 ft BOO MW 1500 1994 3 1750 150 2460 3400 49
2 Vee 2350 ft 400 MW 1060 1997 2330 150 3870 4910 47
TOTAL SYSTEM 1200 MW 2560
2.2 High Devil Canyon
00 1630 ft 400 MW 1140 1993 3 1610 100 1770 2020 58 I .,. 2 High Devil Canyon
~ add 400 MW Capacity
raise dam to 1775 ft 500 1996 1750 150 2460 3400 49
3 Vee 2350 ft 400 MW 1060 1997 2330 150 3870 4910 47
TOTAL SYSTEM 1200 MW 2700
2.3 High Devil Canyon
1775 ft 400 MW 1390 1994 3 1750 150 2400 2760 79
2 High Devil Canyon
add 400 MW capacity 140 1994 1750 150 2460 3400 49
3 Vee 2350 ft 400 MW 1060 1997 2330 150 3870 4910 47
TOTAL SYSTEM 1200 MW 2590
3.1 Watana 2225 ft BOO MW 1860 1993 2200 150 2670 3250 46
2 Watana add 50 MW
tunnel 330 MW 1500 1995 1475 4 4890 5430 53
TOTAL SYSTEM 1180 MW 3360
TABLE 8. 9 (Continued)
Cumulative
Stage/Incremental Data System Data
Annual
Maximum Energy
Capital Cost Earliest Reservoir Seasonal Production Plant
$ Millions On-line Full Supply Draw-Firm Avg. Factor
Plan Stage ConstrtJction (1980 values) Date 1 Level -ft. down-ft. GWH GWH %
3.2 Watana 2225 ft 400 MW 1740 1993 zzon 150 2670 2990 85
2 Watana add 400 MW
capacity 150 1994 2200 150 2670 3250 46
3 Tunnel 330 MW add
50 MW to Watana 15on 1995 1475 4 4890 5430 53
3390
CP 4.1 1 Watana
I
1995 3 ..,. 2225 Ft 400 MW 1740 22no 150 2670 2990 85 N
2 Watana add 400 MW
capacity 150 1996 2200 150 2670 3250 46
3 High Devil Canyon
1470 ft 400 MW 860 1998 1450 100 4520 5280 50
4 Portage Creek
1030 ft 150 MW 650 2000 1028 50 5110 6000 51
TOTAL SYSTEM 135 0 MW 3400
~:
(1) Allowing for a 3 year overlap construction period between major dams.
(2) Plan 1.2 Stage 3 is less expensive than Plan 1.3 Stage 2 due to lower rrobilization costs.
{3) Assumes FERC license can be filed by June 1984, ie. 2 years later than for the Watana/Devil Canyon Plan 1.
TABLE 8.10-ENERGY SIMULATION SENSITIVITY
Reservoir Maximum
Installed full Supply Reservoir Annual Energl-Gwh Plant
Capacity Level Drawdown Factor
1
Development M\t/ Feet feet firm (%) Average (%) %
Watana 2225 feet BOO 2200 100 2510 (89) 3210 ( 101) 45.8
800 2200 150 2670 (94) 3250 (103) 46.4
BOO 2200 175 2770 (98) 3200 (101) 45.7
BOO 2200 Unlimited 2B30 (100) 3170 (100) 45.2
Notes:
(1) Second lowest energy generated during simulation period.
8-43
TABLE 8.11. SUS!TNA ENVIRONMENTAL DEVELOPMENT PLANS
Stage/lncremental Data
Maximum
Capital Cost EarliP.st Reservoir Seasonal Plant
$ Mi !lions On-line Full Supply Draw-Factor
Plan Stage Construction (1980 values) 1 ~ Date Level -ft. down-ft GWH ~
E1.1 Watana 2225 ft 800MW
and Re-Regulation
Dam 1960 1993 2200 150 2670 3250 46
2 Devil Canyon 1470 ft
400MW 900 1996 1450 100 5520 6070 58
TOTAL SYSTEI~ 1200MW '2llbiT
00 E1.2 1 Watana 2~60 ft 400MW 1570 1992 2000 100 1710 2110 60
I 2 Watana raise to _.,.
2225 ft 360 1995 2200 150 2670 2990 85 _.,.
3 Watana add 400MW
capacity and
Re-Regulation Dam 230 2 1995 2200 150 2670 3250 46
4 Devil Canyon 1470 ft
400MW 900 1996 1450 100 5520 6070 58
TOTAL SYSTEM 1200MW Jll6IT
E1.3 1 Watana 2225 ft 400MW 1740 1993 2200 150 2670 2990 85
2 Watana add 400MW
capar.ity and
Re-Regulation Dam 250 1993 2200 150 2670 3250 46
3 Devil Canyon 1470 ft
408 MW 908 1996 1450 100 5520 6070 58
TOTAL SYSTEM 1200MW "2ll9IT
TABLE 8.11 (Continued)
Cumulative
Stage/Incremental Data System Data
Annual
Maximum Energy
Capital Cost Earliest Reservoir Seasonal Production Plant
$ Millions Ill-line Full Supply Draw-Firm Avg. Factor
Plan Stage Construction (1980 values) Date 1 Level -ft. down-ft. GWH GWH %
E1.4 Wa tan a 2225 ft 400MW 1740 1993 2200 150 2670 2990 85
2 Devil Canyon 1470 ft
400MW 900 1996 1450 100 5190 5670 81
TOTAL SYSTEM 800MW 2640
E2.1 1 High Devil Canyon
1775 ft BOOMW and
00 Re-Regulation Dam 1600 1994 3 1750 150 2460 3400 49 I .,. 2 Vee 2350ft 400MW 1060 1997 2330 150 3870 4910 47
<.r1 TOTAL SYSTEM 1200MW 2660
E2.2 1 High Devil Canyon
1630 ft 400MW 1140 1993 3 1610 100 1770 2020 58
2 High Devil Canyon
raise dam to 1775 ft
add 400MW and
Re-Regulation Dam 600 1996 1750 150 2460 3400 49
3 Vee 2350 ft 400 MW 1060 1997 2330 150 3870 4910 47
TOTAL SYSTEM 1200MW 2800
E2.3 1 High Devil Canyon
1775 ft 400MW 1390 1994 3 1750 150 2400 2760 79
2 High Devil Canyon
add 400MW capar.ity
and Re-Regulation
Dam 240 1995 1750 150 2460 3400 49
3 Vee 2350 ft 400MW 1060 1997 2330 150 3870 4910 47
TOTAL SYSTEM 1200 2690
TABLE 8.11 (Continued)
umu a 2ve
Stage/Incremental Data Si:stem Data
Annual
Maximum Energy
Capital Cost Earliest Reservoir Seasonal Production Plant
$ Mi !lions On-line Full Supply Draw-Firm Avg. Factor
Plan Stage Construction (1980 values) Date 1 Level -ft. down-ft. GWH GWH %
E2.4 1 High Devil Canyon
1755 ft 400MW 1390 1994 3 1750 150 2400 2760 79
2 High Devil Canyon
add 400MW capacity
and Portage Creek
Dam 150 ft 790 1995 1750 150 3170 4080 49
3 Vee 2350 ft
400MW 1060 1997 2330 150 4430 5540 47
TOTAL SYSTEM TI"Iiil"
00 E3.2 1 Watana
I 2225 ft 400MW 1740 1993 2200 150 2670 2990 85 _,.
"' 2 Watana add
400 MW capacity
and Re-Regul at ion
Dam 250 1994 2200 150 2670 3250 46
3 Watana add 5fljW
Tunnel Scheme 330MW 1500 1995 1475 4 4890 5430 53
TOTAL SYSTEM 1180MW mrr
E4.1 Watana
2225 ft 400MW 1740 1995 3 2200 150 2670 2990 85
2 Watana
add 4~8MW capacity
and Re-Regulation
Dam 250 1996 2200 150 267fJ 3250 46
3 High Devil Canyon
14 70 ft 400MW 860 1998 1450 100 4520 5280 50
4 PortagP-Creek
1030 ft 150MW 650 2000 1020 50 5110 6000 51
TOTAL SYSTEM 1350 MW >miT
NOTES:
m-Al lowing for a 3 year overlap construction period between major dams.
(2) Plan 1.2 Stage 3 is less expensive than Plan 1.3 Stage 2 d1.te to lower 100bilization costs.
(3) Assumes FERC license can be filed by JtJne 1984, ie. 2 years later than for the Watana/Devil Canyon Plan 1 a
TABLE 8.12-ANNUAL fiXED CARRYING CHARGES
-·;oo
Economic Parameters
Total
Economic Cost of Annual
Life Money Amortization Insurance Fixed Cost
Project Type -Years % OJ % % 10
Thermal -Gas Turbine
(Oil fired) 20 3.00 3,.7.2 0.25 6.97
-Diesel, Gas Turbine
(Gas fired) and
Large Stearn '· Turbine 30 3.00 2.10 0.25 5.35
-Small Stearn Turbine 35 3.00 1.65 0.25 4.90
Hydropower 50 3.00 0.89 0.10 3.99
"
8-47
TABLE B.13-RESULTS OF ECONOMIC ANALYSES OF SUSITNA PLANS-MEDIUM LOAD FORECAST
!lus1Ena rleveloement Plan Inc. InstalLed Capac1£y (MW) by Ictal System Iota! System
On hne OaEes Cate9or~ in 2010 Installed Present Remarks Pertaining to
Plan Stages OGP5 Run lhermal Hydro Capacity In Worth Cos~ the Susitna Basin
No. 1 2 3 4 Id. No. Coal Gas l:hi DEfier !lus1£na 2010-MW $ Million DeveloEment Plan
E1.1 1993 2000 LXE7 300 426 0 144 1200 2070 5B50
E1.2 1992 1995 1997 2002 L5Y9 200 501 0 144 1200 2045 6030
E1. 3 1993 1996 2000 LBJ9 300 426 0 144 1200 2070 5B50
1993 1996 L7W7 500 651 0 144 BOO 2095 6960 Stage 3, Devil Canyon Dam
not constructed
199B 2001 2005 LAD7 400 276 30 144 1200 2050 6070 Delayed implementation
schedule
E1.4 1993 2000 LCK5 200 726 50 144 BOO 1920 5B90 Total development limited
to BOO MW
Modified
E2.1 1994 2000 LB25 400 651 60 144 BOO 2055 6620 High Devil Canyon limited
to 400 MW
00 E2. 31 1993 1996 2000 L601 300 651 20 144 1200 2315 6370 I 1993 1996 LE07 500 651 30 144 800 2125 6720 Stage 3, Vee Dam, not .,.
00 constructed
Modified
E2.3 1993 1996 2000 LEB3 300 726 220 144 1300 2690 6210 Vee dam replaced by
Chakacharma dam
3.1 1993 1996 2000 L607 200 651 30 144 1180 2205 6530
Special
3.1 1993 1996 2000 L615 200 651 30 144 1180 2205 6230 Capital cost of tunnel
reduced by 50 percent
E4.1 1995 1996 1998 LTZ5 200 576 30 144 1200 2150 6050 Stage 4 not constructed
NOTES:
( 1) Adjusted to incorporate cost of re-regulation dam
TABLE 8.14-RESULTS OF ECONOMIC ANALYSES OF SUSITNA PLANS-LOW AND HIGH LOAD FORECAST
Susitna Develo2m7nt Plan Inc. Installed Capacity (MW) by Total System Total System
Onl~ne Oates Categor~ in 2010 Installed Present Remarks Pertaining to
Plan Stages OGP5 Run Thermal H~dro Capacity In Worth Cost the Susitna 8asin
No. 1 2 ~ 4 ld. No. -Loal r!as Oil Other Susitna 2010-MW $ Million Development Plan
VERY LOW FORECAST1
E1 .. 4 1997 2005 L7B7 0 651 .50 144 800 1645 3650
LOW LOAD FORECAST
E1.3 1993 1996 2000 Low energy de~~ does not
warrant plan c~ties
E1.4 1993 2002 LC07 0 351 40 144 BOO 1335-4350
1993 LBK7 200 501 80 144 400 1325 49!~0 Stage 2, Oevll C&nyon Dam,
not constructed
E2.1 1993 2002 LG09 100 426 30 144 BOO 1500 . 456\'J High Devil Can~ limited
to 400 MW
1993 LBU1 400 501 0 144 400 1445 485GI Stage 2, Vee il~t not
co constructed
I
~ E2.3 1993 1996 2000 Low energy d~nd does not ~
warrant plan c~ities
Special
3.1 1993 1996 2000 L613 0 516 20 144 780 1520 4730 Capital cost uf tunnel
reduced by 50 pel:'Cent
3.2 1993 2002 L609 0 516 20 144 780 1520 5000 Stage 2, 400 Mtt addition
to Watana, not toostructed
HIGH LOAD FORECAST
E1.3 1993 1996 2000 LA73 1000 951 0 144 1200 3295 10680
Modified
2005 2 £1.3 1993 1996 2000 LBV7 800 651 60 144 1700 3355 10050 Ch,akachamna hy~lectric
generating station (480 MW)
brc!Ught on line .as a rourth
sta1ge
£2 .• 3 1993 1996 2000 LBV3 1300 951 90 144 1200 368.5 11720
Modified
2003 2 E2.3 1993 1996 2000 LBY1 1000 876 10 144 1100 3730 11040 Chakachamna hydroelectric
generating station (480 MW)
brought on line as a fourth
stage
NOTE: -
(1) Incorporating load management and conservation
Oescri[!tion
Parameter Var~ed
Interest Rate
Fuel Cost ($million Btu,
natural gas/coal/oil)
Fuel Cost Escalation (%,
natural gas/coal/oil)
Economic Life of Thermal
Plants (year, natural
(') gas/coal/oil)
I
<.n
0 Thermal Plant Capital
Cost ($/kW, natural gas/
coal/oil)
Watan~/Oevil Canyon Capital
Cost-($million, Watana/
Devil Canyon)
Probabilistic Load Forecast
NOTES:
(1) Alaskan cost adjustment
(2) Excluding AFDC
TABLE 8.15-RF.SULTS OF ECONOMIC SENSITIVITY ANALYSES FOR GENERATION SCENARIO
INrORPORATING SUSITNA 8ASIN DEVELOPMENT PLAN E1.3-MEDIUM FORECAST
o a o a
System System
Installed Capacity (MW) by Installed Present
Categorl in 2010 Capacity Worth
Parameter OGPS Run IFiermaJ R~aro In 2010 Cost
Values !d. No. l":oai Gas [hi Other Sus1tna MW $ Million
5% LF85 300 426 0 144 1200 2070 4230
9% LF87 300 426 0 144 1200 2070 2690
1.60/0.92/3.20 L533 100 576 20 144 1200 2040 5260
0/0/0 L557 0 651 30 144 1200 2025 4360
3.98/0/3.58 L563 300 426 0 144 1200 2070 5590
45/45/30 L585 45 367 233 144 1200 1989 6100
350/2135/778 LED7 300 426 0 144 1200 2070 5740
1990/1110 L5G1 300 426 0 144 1200 2070 6210
2976/1350 LD75 300 426 0 144 1200 2870 6810
L8T5 200 1476 140 144 1200 3160 6290
factor reduced from 1. 8 to 1.4
Remarks
21)% fuel cost reduction
Zero escalation
Zero coal cost escalation
Economic lives increased
by 50%
Coal capital cost reduced
by 22%
Capital cost for Devil
Canyon Dam increased by 23%
Capital cost for both dams
increased by 50%
TABLE 8.16-ECONOMIC BACKUP DATA fOR EVALUATION Of PLANS
Parameter
Capital Investment
Fuel
Operation and Maintenance
TOTAL:
Iota! Present Worth ·cast For 1981 -zo40
Period $ Million (% Total)
Generation Pian
With High Devil
Canyon -Vee
2800 (44)
3220 (50)
350 (6)
6370 (100)
Generatlon Plan Generat1on Plan
With Watana -With Watana -
Devil Can):'on Dam Tunnel
2740 (47) 3170 (49)
2780 (47) 3020 (46)
330 (6) .340 (5)
5850 (100) 6530 {100)
8-51
All Themal
Generation Plans
2s2n Ol>
524.0 (64)
370 (5)
8130 (100)
co
I
(j1
N
TABLE 8.17-ECONOMIC EVALUATION OF DEVIL CANYON DAM AND TUNNEL SCHEMES AND WATANA/DEVIL CANYON AND HIGH DEVIL CANYON/VEE PLANS
ECONOMIC EVALUATION:
-Base Case
SENSITIVITY ANALYSES:
-Load Growth
-Capital Cost Estimate
-Period of Economic
Analysis
-Discount Rate
-Fuel Cost
-Fuel Cost Escalation
-Economic Thermal Plant
Life
Low
High
Period shortened to
(1980 -2010)
5%
8% (interpolated)
9%
680
650
N.A.
Higher uncertainty assoc-
iated with tunnel scheme.
230
520
210
1040
generation
Higher uncertainty associated with
H.D.C./Vee plan.
160
As both the capital and fuel costs associated with the tunnel
80% basic fuel cost scheme and H.D.C./Vee Plan are higher than for Watana/Devil
Canyon plan any changes to these parameters cannot reduce the
0% fuel escalation Devil Canyon or Watana/Devil Canyon net benefit to below zero.
0% coal escalation
50% extension
0% extension
Remarks
Economic ranking: Devil Canyon
dam scheme is superior to Tunnel
scheme. Watana/Devil Canyon dam
plan is superior to the High
Devil Canyon dam/Vee dam plan.
The net benefit of the
Watana/Devil Canyon plan remains
positive for the range of load
forecasts considered. No change
in ranking.
Higher cost uncertainties asSoci-
ated with higher cost
schemes/plans. Cost uncertainty
therefore does not affect
economic ranking.
Shorter period of evaluation
decreases economic differences.
Ranking remains unchanged.
Ranking remains unchanged.
c:>
I
(}1
w
TABLE 8.18 -ENVIRONMENTAL EVALUAllON OF DEVIl CANYON OAM AND TUNNEL SCHEME
Environmental
Attribute
Ecological:
-Downstream fisheries
and Wildlife
Resident fisheries:
Wildlife:
Cultural:
Land Use:
Concerns
Effects resulting
from changes in
water quantity and
quality.
loss of resident
fisheries habitat.
Loss of wildlife
habitat.
Inundation of
archeological sites.
Inundat ion of Oev il
Canyon.
Appratsal
(Differences in impact
of two schemes)
t-.b significant differ-
ence between schemes
regarding effects down-
at ream of Oev U Canyon.
Oi fference in reach
bet ween Oev il Canyon
dam and tunnel re-
regulat ion dam.
Minimal differences
between schemes.
Minimal differences
between schemes.
Potential differences
bet ween schemes.
Significant difference
bet ween schemes.
Identification
of difference
With the tunne 1 scheme con-
trolled flows between regula-
tion dam and downstream power-
house offers potential for
anodromous fisheries enhance-
ment in this 11 mile reach of
the river.
Devil Canyon dam would inundate
27 miles of the Susitna River
and approximately 2 miles of
Devil Creek. The tunnel scheme
would inundate 16 miles of the
Susitna River.
The most sensitive wildlife ha-
bitat in this reach is upstream
of the tunne 1 re-regulation dsm
where there is no significant
difference between the schemes.
The Oev il Canyon dam scheme in
addition inundates the river
valley between the two dam
sites resulting in a moderate
increase in impacts to
wildlife.
Due to the larger area inun-
dated the probabll ity of inun-
dating archeological sites is
increased.
The Oev H Canyon is considered
a unique resource, 80 percent
of which would be inundated by
the Devil Canyon dam scheme.
This would result in a loss of
both an aesthetic value plus
the potential for white water
recreation.
OVERALL EVALUATION: The tunnel scheme has overall a lower impact on the environment.
Appraisal Judgement
t-.bt a factor in evaluot ion of
scheme.
If fisheries enhancement oppor-
tunity can be realized the tun-
nel scheme offers a positive
mitigation measure not available
with the Devil Canyon dam
scheme. This opportunity is
considered moderate and favors
the tunnel scheme.
This reach of river is not con-
sidered to be highly significant
for resident fisher lea and thus
the difference between the
schemes is minor and favors the
tunnel scheme.
The difference in loss of wild-
life habitat is considered mod-
erate and favors the tunne 1
scheme.
A significant archeological
site, if identified, can proba-
bly be excavated. This concern
is not cons ide red a factor in
in scheme evaluation.
The aesthet ic and to some extent
the recreational losses associ-
ated with the development of the
Devil Canyon dam is the main
aspect favoring the tunnel scheme.
5cheme JUdged to have
the least potential ii!Jlact
funnel DC
X
X
X
Soc1al
Aspect
Potential
non-renewable
resource
displacement
Impact on
state economy
Impact on
local economy
Seismic
exposure
Overall
Evaluation
TABLE 8.19-SOCIAL EVALUATION OF SUSITNA BASIN DEVELOPMENT SCHEMES/PLANS
Parameter
Million tons
Beluga coal
over 50 years
J
Risk of major
structural
failure
Potential
impact of
failure on
human life.
tunnel
Scheme
Devil Canyon
Dam Scheme
H1gh Dev1l Canyon/
Vee Plan
Watana/DeV11
Canyon Plan
80 110 170 210
..
All projects would have similar impacts on the state and
local economy.
All projects designed to similar levels of safety.
Any dam failures would effect the same downstream
population.
1. Devil Canyon dam superior to tunnel.
2. Watana/Devil Canyon superior to High Devil Canyon/Vee plan.
Remarks
Devil Canyon dam scheme
potential higher than
tunnel scheme. Watana/
Devil Canyon plan higher
than High Devil Canyon/
Vee plan.
Essentially no difference
between plans/schemes.
TABLE 8.20 -ENERGY CONTRIBUTION EVALUATION OF THE DEVIL
CANYON DAM AND TUNNEL SCHEMES
Parameter
Total Energy Production
Capab1hty
Annual Average Energy GWH
Firm Annual Energy GWH
% Basin P~tential
Developed
Enerry Potential Not
Deve oped GWH
Notes:
Dam
2850
2590
43
60
lunnel
2240
2050
32
380
Remarks
Devil Canyon dam annually
develops 610 GWH and 540
GWH more average and firm
energy respectively than
the Tunnel scheme.
Devil Canyon schemes
develops more of the
basin potential.
As currently envisaged,
the Devil Canyon dam does
not develop 15 ft gross
head between the Watana
site and the Devil Canyon
reservsoir. The tunnel
scheme incorporates addi-
tional friction losses in
tunnels. Also the compen-
sation flow released from
re-regulation dam is not
used in conjunction with
head between re-regulation
dam and Devil Canyon.
(1) Based on annual average energy. Full potential based on USSR four
dam scheme.
8-55
TABLE 8.21 -OVERALL EVALUATION OF TUNNEL SCHEME AND DEVIL CANYON DAM SCHEME
Ali RIBUtE
Economic
Energy
Contribution
Environmental
Social
Overall
Evaluation
SUPERIOR PLAN
Devil Canyon Dam
Devil Canyon Dam
Tunnel
Devil Canyon Dam (1>1arginal)
Devil Canyon dam scheme is superior
Tradeoffs made:
Economic advantage of dam scheme
is judged to outwei<jl the reduced
environmental impact associated
with the tunnel scheme.
8-56
co
I
(J1
-....J
Environmental Attribute
Ecolopical:
1) 1sheries
2) Wildlife
a) Moose
b) Caribcu
c) Furbearers
d) Birds and Bears
TABLE 8. 22 -ENVIRONMENTAL EVALUATION OF WATANA/DEVlL CANYON AND HIGH DEVIL CANYON/VEE DEVELOPMENT PLANS
Plan Comparison
No significant difference in effects on downstream
anadromous fisheries.
HOC/V would inundate approximately 95 miles of the
Susitna River and 28 miles of tributary streams, in-
cluding the Tyone River.
W/OC would inundate approximately 84 miles of the
Susitna River and 24 miles of tributary streams,
including Walana Creek.
IIOC/V would inundate 123 miles of critical winter river
bottom habitat.
W/OC would inundate 108 miles of this river bottom
habitat.
flOC/V would inundate a large area upstream of Vee
utilized by three sub-populations of moose that range
in the northeast sect ion of lhe basin.
W/OC would inundate the Watana Creek area utilized by
moose. The condition of this sub-population of moose
and the quality of the habitat they are using appears
to be decreasing.
The increased length of river flooded, especially up-
stream from the Vee dam site, would result in the
HOC/V plan creating a greater potE'ntial division of
the Nelchina herd's range. In addition, an increase
in range would be directly inundated by the Vee res-
ervoir.
The area flooded by the Vee reservoir is considered
important to some key furbearers, particularly red fox.
This area is judged to be more important than the
Watana Creek area that would be inundated by the W/OC
plan.
Forest habitat, important for birrls and black bears,
exist along the valley slopes. The loss of this habi-
t at would be greater with the W/OC plan.
There is o high potential for discovery of archeologi-
cal sites in the easterly region of the Upper Susitna
Basin. The BOC/V plan has a greater potential of
affecting these sites. For other reaches of the river
the difference between plans is considered minimal.
Appraisal Judgement
Due to the avoidance of the Tyone River,
lesser inundation of resident fisheries
habitat and no significant difference in the
effects on anadromous fisheries, the W/IJC plan
is judged to have less impact.
Due to the lower potential for direct impact
on moone populations within the Susitna, the
W/OC plan is judged superior.
Dm to the potential for a greater impact on
the Nelchina caribou herd, the BOC/V scheme
is considered inferior.
Due to the lesser potential for impact on fur-
bearers the W/OC is judged to be superior.
The HOC/V plan is judged superior.
The W/OC plan is judged to have a lower po-
tential effect on archeological sites.
X
X
X
X
X
(X)
I
U1
(X)
TABLE 8. 22 (Continued)
Environmental Attribute
Aesthetic/
Land Use
Plan Comparison
With either scheme, the aesthetic quality of both
Devil Canyon and Vee Canyon would b" impaired. The
HDC/V plan would also inundate Tsusena falls.
Due to construction at Vee Dam site and the size of
the Vee Reservoir, the HDC/V plan would inherently
create access to more wilderness area than would the
W/DC plan.
Appraisal Judgement
8oth plans impact the valley aesthetics. The
difference is considered minimal.
As it is easier to extend access than to
limit it, inherent access requirements were
considered detrimental and the W/DC plan is
judged superior. The ecological sensitivity
of the area opened by the HDC/V p len rein-
forces this judgement.
OVERALL EVALUATION: The W/DC plan is judged to be superior to the HDC/V plan.
(The lower impact on birds and bears associated with HDC/V plan is considered to be outweighed by all
the other impacts which favour the W/DC plan.)
NOTES:
W = Watana Dam
DC = Oev il Canyon Dam
HOC = High Devil Canyon Dam
V = Vee Dam
X
TABLE 8.23 -ENERGY CONTRIBUTION EVALUATION OF THE WATANA/DEVIL CANYON
AND HIGH DEVIL CANYON/VEE PLANS
Parameter
Total Energy Production
Capability
Annual Average Energy GWH
Firm Annual Energy GWH
% Basin Potential
Developed (1)
Eneriy Potential Not
Deve oped GWH (2)
Notes:
Watana/
Devil Canyon
6070
5520
91
61)
High Devil
Canyon/Vee
4910
3870
81
650
Remarks
Watana/Devil Canyon
plan annually devel-
ops 1160 GWH and
1650 GWH more average
and firm energy re-
pectively than the
High Devil Canyon/Vee
Plan.
Watana/Devil Canyon
plan develops more of
the basin potential
As currently con-
ceived, the Watana/-
Devil Canyon Plan
does not develop 15
ft of gross head
between the Watana
site and the Devil
Canyon reservoir.
The High Devil
Canyon/Vee Plan does
not develop 175 ft
gross head between
Vee site and High
Devil reservoir.
( 1) Based on annual average energy. Full potential based on USBR four
dam schemes.
(2) Includes losses due to unutilized head.
8-59
TABLE 8.24 -OVERALL EVALUATION OF THE HIGH DEVIL CANYON/VEE AND
WATANA/DEVIL CANYON DAM PLANS
AIIRIBOIE
Economic
Energy
Contribution
Environmental
Social
Overall
Evaluation
SUPERIOR PLAN
Watana/Devil Canyon
Watana/Devil Canyon
Watana/Devil Canyon
Watana/Devil Canyon (Marginal)
Plan with Watana/Devil Canyon is
superior
Tradeoffs made: None
8-60
TABLE 8.25 -RESULTS OF ECONOMIC ANALYSES FOR GENERATION SCENARIO
INCORPORATING THERMAL DEVELOPMENT PLAN -MEDIUM FORECAST
Total System Total
Installed Capacity (MW) Installed System
by Category in 2010 Capacity Present
Description Parameter OGP5 Run Thermal In 2010 Worth Cost
Parameter \laried Value Id. No. l'!oai Cas !HI Hydro Total MW $ Million Remark-s;
Interest Rate 5% LEA9 900 800 50 •f44 1895 5170
9% LEB1 900 801 50 1t~4 1895 2610
Fuel Cost ($ million Btu,
natural gas/coal/oil) 1.60/0.92/3.20 L1K7 800 876 70 144 1890 7070 20% fuel c~i!: reduction
Fuel Cost Escalation (%,
natural gas/coal/oil) 0/0/0 L547 0 1701 10 144 1855 4560 Zero escalatitJn
3.98/0/3.58 L561 1100 726 10 144 1980 6920 Zero coal c0$t escalation
Economic Life of Thermal
Plants (year~ natural
45/45/30 gas/coal/oil L583 1145 667 51 144 2007 7850 Economic li f~ increased
co I'! 50%
r
"" Thermal Plant Capital __.
Cost ($/kW, natural gas/ 350/2135/778 LAL9 1100 726 10 144 1980 7590 Coal capital ~t reduced
coal/oil) by 22%
co
I
0)
N
Parameters
LOAD GROWTH
CAPITAL COST ESTIMATE
PERIOD OF ECONOMIC ANALYSIS
DISCOUNT RATE
FUEL COST
FUEL COST ESCALATION 5
ECONOMIC THERMAL PLANT
LIFE
Notes:
TABLE 8.26 -ECONOMIC SENSITIVITY OF COMPARISON OF GENERATION PLAN WITH
WATANA/DEVIL CANYON AND THE ALL THERMAL PLAN
Present worth of Net Benefit ($million) of total generation
system costs·for the Watana/Devil Canyon plan over the all thermal plan.
Sensitivity Analyses
Very low
Low
Medium
High
Low Thermal Cost2
High 3Hydroelectric
Cost
1980 -2040
1980 -2010
8~~ (interpolated)
9 ., ,.
0% escalation for all
fuels
m~ escalation for
coal only
5m~ extension to all
thermal plant life
Present worth ($ m1llion)
1280
1570
2280
2840
1850
1320
2280
960
2280
940
0
-80
1810
200
1330
1800
Remarks
The net benefit of the Watana/Devil Canyon Plan re-
mains positive for the range of load forecasts con-
sidered.
System costs relatively insensitive. Capital cost
estimating mcertainty does not effect economic
ranking.
Shorter period of evaluation decreases economic dif-
ferences. Ranking remains unchanged.
Below discount rate of 8% the Watana/Devil Canyon
plan is economically superior.
Watana/Devil Canyon plan remains economically super-
ior for wide range of fuel prices and escalation
rates.
Economic benefit for Watana/Devil Canyon plan rela-
tively insensitive to extended thermal plan economic
life.
(1) All parameters, except load growth, tested using medium load forecast.
(2) Thermal capital cost decreased by 22~~.
(3) Estimated Susitna cost increased by 50~~.
(4) All fuel costs reduced by 20%. Base case costs $/million Btu: Coal 1.15, Gas 2.00, Oil4.00
(5) Base case escalation: Coal 2.93%, Gas 3.98%, Oil 3.58%.
co
I
0)
w
Social Aspect
Potential non-renewable
resource displacement
Impact on state economy
Impact on local economy
Seismic e>:.posure
Overall
Comparison
TABLE 8.27 -SOCIAL COMPARISON OF SYSTEM £L:NERATION PLAN WITH
< WATANA/DEVIL CANYON AND THE All iHERMAL PLAN
Parameter
Million tons of
Beluga coal, over
50 years
Direct & Indirect
employment and in~
come.
Business investment.
Risk of major
structural failure
Potential impact of
failure on human
life.
All lhermal
Generation Plan
Gradually, contin-
uously growing
impact.
Generat2on Plan w2th
Watana/Devil Canyon
210
Potentially more dis-
ruptive impact on
economics.
All projects designed to similar levels of
safety.
Failure would effect
only operating per-
sonnel. Forecast of
failure would be im-
possible.
Failure would effect
larger number of people
located downstream,
however, some degree of
forecasting dam failure
would be impossible.
No significant difference in terms of
overall assessment of plans.
Remarks
With Watana/Devil
Canyon plan is
superior.
Available information
insufficient to draw
definite conclusions.
Both scenarios judged
to be equal.
TABLE 8.28 -GENERIC COMPARISON OF ENVIRONMENTAL IMPACTS OF A SUSITNA
BASIN HYDRO DEVELOPMENT VERSUS COAL FIRED THERMAL
GENERATION IN THE BELUGA COAL FIELDS
Environmental
Attributes
Ecological:
Cultural:
Aesthetic/
Land Use:
Concerns
Sus1tna Basin Development
Potential impact on fisheries
due to alteration of down-
steam flow distribution and
water quality. Inundation of
Moose and furbearer habitat
and potential impact on
Caribou migration. No major
air quality problems, only
minor microclimatic changes
would occur.
Inundation of archeological
sites.
Inundation of large area and
surface disturbance in con-
struction area. Creates addi-
tional access to wilderness
areas, reduces river recrea-
tion but increases lake rec-
reational activities.
8-64
Thermal Generation
Potential for impact on
fisheries resulting from
water quality impairment of
local streams and local
habitat destruction due to
surface disturbances both at
mine and generating facili-
ties. Impact on air quality
due to emission of particu-
lates so 2 , NO , trace
metals and wa~er vapours
from generating facilities.
Potential destruct ion of
archeological sites.
Surface disturbance of large
areas associated with coal
mining and thermal genera-
tion facilities. Creates
additional access and may
restrict land use activi-
ties.
TABLE 8.29 -OVERALL EVALUATION OF ALL THERMAL GENERATION PLANS
WITH THE GENERATION PLAN INCORPORATING WATANA/DEVIL
CANYON DAMS
AltRIBUTE
Economic
Environmental
Social
Overall
Evaluation
suPERIOR PLAN
With Watana/Devil Canyon
Unable to distinguish difference in
this study due to site specific
nature of impacts
No significant overall difference
Plan with Watana/Devil Canyon is
judged to be superior
Tradeoffs made: Not fully explored
8-65
PREVIOUS
STUDIES AND
FIELD
RECONNAISSANCE
12DAM
SITES SCREEN
ENGINEERING
LAYOUT AND
COST STU Dl ES
7DAM
SITES
COMPUTER MODELS
TO DETERMINE
LEAST COST DAM
COMBINATIONS
3 BASIC
DEVELOP-
MENT
PLANS
DATA ON DIFFERENT
THERMAL GENERATING
SOURCE;..;::S;__ ____ ~....-___,
COMPUTER MODELS
TO EVALUATE
-POWER AND
ENERGY YIELDS
-SYSTEMWIDE
ECONOMICS
GOLD CREEK CRITERIA DEVIL CANYON
DEVIL CANYON 1-E-C_O_N_O_M_IC-S-----l HIGH DEVIL
OBJECTIVE
ECONOMIC
WATANA I DEVIL
CANYON
CRITERIA WATANA I DEVIL
CANYON
HIGH DEVIL CANYON ENVIRONMENTAL CANYON
DEVIL CREEK ALTERNATIVE WATANA
WATANA SITES SUSITNA m
SUSITNA ill ENERGY VEE
VEE CONTRIBUTION MACLAREN
MACLAREN DENALI
DENALI
BUTTE CREEK
TYONE
'---------'HIGH DEVIL
CANYON/ VEE
HIGH DEVIL
CANYON I WATANA
ADDITIONAL SITES
PORTAGE CREEK
ECONOMIC
ENVIRONMENTAL
SOCIAL
ENERGY
CONTRIBUTION
PLUS THERMAL
LEGEND
DIS HIGH DEVIL CANYON
DIS WATANA
~STEP NUMBER IN
STANDARD PROCESS
(APPENDIX A)
SUSITNA BASIN PLAN FORMULATION AND SELECTION PROCESS
FIGURE 8.1 •
PORTAGE CR.
-
100
I
.., ..
H
<r z _,_
u;
·;:::,
Cl) -z
~ ~ z <t <[ u <[ 1905'-z
~~ z t: ....J £i <( (/J > 0 1-2050.!. ::l lL! ~ (/J
0 (/J
:z: ....J 2200' > (!) w
. ~, > :r: 0 1750'
0:: (I) w
r--f450' ~ dl 0 -
~ 1 ~ (!) I 1000 1
870 --11-
to2d
500'
120 140 160 ISO
RIVER Mt• ... ES .,
l&J w >
200
OSHETNA RIVER
,....----~ 2000 1
I
I
I
I
~__._.._.,li. TJ--TYONE RIVER
1------"-"""'-2000 1 F
I
I
I ~·
I I fS z
I w
!i I ;:J I 1-....J I t-
I u z => <t l&J ~m 0
RIVER
w 1-
I 2350'! ::1!2395!~ 2535 _____ ..,_
l I II
1.. I
!..,.,.-
L2300'
220 240 260 280
3
2
2
I
PROFILE THROUGH ALTERNATIVE SITES
FIGURE 8.2 [i]
00
1 m
00
I
GOLD
CREEK OLSON DEVIL
CANYON
HIGH
DEVIL
CANYON·
DEVIL
CREEK WATANA SUSITNA:m VEE
HIGH DEVIL CANYON
DEVIL CREEK
WATANA.
SUSITNA m.
LEGEND
COMPATIBLE ALTERNATIVES VEE
D
MUTUALLY EXCLUSIVE ALTERNATIVES
~
DAM lN COLUMN IS MUTUALLY EXCLUSIVE IF FULL
··: .. :. : · · ·:: SUPPLY LEVEL OF DAM IN ROW EXCEEDS THIS VALUE-FT.
·:t4:E'~5 .. ···::(~i):5} . VALUE IN BRACKET REf:-ERS TO APPROXIMATE DAM HEIGHT.
MACLAREN
DENALI
MACLAREN DENALI
. ·.·-.· .. · ·,_··.·
'. ~ '. .
BUTIE 'CREEK
TYONE
MUTUALLY EXCLUSIVE DEVELOPMENT ALTERNATIVES
BUTTE ~
CREEK ~
~
t!
H
H
·-·
TYONE
FIGURE a5 lil
<.D
0
)( -
<Do
>< -1-
(/)
0
0
1500
1000
500
• ;oo ••
DEVIL CANYON
. . : .
1000 2000 3000
RESERVOIR STORAGE (10 3 x A F)
HIGH DEVIL CANYON
1000
LEGEND
e COST DEVELOPED DIRECTLY FROM
ENGINEERING LAYOUTS
COST BASED ON ADJUSTMENTS TO
O VALUES DETERMINED FROM LAYOUTS
1500
4000
DAMSITE COST VS RESERVOIR STORAGE CURVES
FIGURE 8.4
8-69
<f -~
(/)
0 u
2400
2000
1860
1600
400
LEGEND
e COST DEVELOPED DIRECTLY FROM
ENGINEERING LAYOUTS
COST BASED ON ADJUSTMENTS TO
O VALUES DETERMINED FROM LAYOUTS
0 o~---2~oo-o---4-o~o-o __ 6_o~o-o---soo~o---lo~o~oo---I-2000~--~~--•
RESERVOIR STORAGE ( 103x AF)
1500
1000
(.!)Q
)( -~
(/)
0 u
500
0
WATANA
1390
1000 2000 3000
RESERVOIR STORAGE ( 103x A F)
SUSITNA liT
4000
DAMSITE COST VS RESERVOIR STORAGE CURVES
FIGURE 8.5
8-70
1000
800
~ 600
)(
~
BOO
600
tD
Q
)( -~ 400
1-
(/)
0
()
200
/500
~
1060
LEGEND
e COST DEVELOPED DIRECTLY FROM
ENGINEERING LAYOUTS
COST BASED ON ADJUSTMENTS TO
0 VALUES DETERMINED FROM LAYOUTS
0~--~----~----~----~--_.----~------~
800
.;;-600
Q
X =
t; 400
0
()
200
0 200 400 600 800 1000 1200 1400
RESERVOIR STORAGE ( 10 3 x AF)
MACLAREN
440
1000 2000 3000 4000 5000
RESERVOIR STORAGE ( 10 3 x AF)
DENALI
DAMSITE COST VS RESERVOIR STORAGE CURVES
FIGURE 8.6
8-71
2200 FT. WATANA 800 MW
•j• 2 MILES
y-----1475 FT.
~--RE -REGULATION DAM
2 TUNNELS
38 FT. DIAMETER
800 MW-70 MW
2 TUNNELS
38 FT. DIAMETER
DEVIL CANYON
550 MW
1150 MW
·-· RE-REGULATION DAM
30 MW
300 MW
30 FT. DIAMETER
800 MW
2 TUNNELS 365 MW
24 FT. DIAMETER
SCHEMATIC REPRESENTATION
OF CONCEPTUAL TUNNEL SCHEMES
TUNNEL
SCHEME
#
I.
2.
3.
4.
FIGURE 8.7
8-72
LEGEND
STAGE I STAGE 2
~ PLAN El
o---0 PLAN E2
~---~ PLAN E3
0-·-·~ PLAN E4
I
/
I
E3.2 Q
I 3
I
I
I
I
E 1.1
1000~-------------------------------------~-----------------+---~
0~---------~------------~------------~------------~------------~------------~~
0 1000 2000 3000 4000 5000
AVERAGE ANNUAL ENERGY-GWH
CAPITAL COST VERSUS ENERGY PLOTS
FOR ENVIRONMENTAL SUSITNA BASIN PLANS
FIGURE
6000
88.
3
~
~ 2
0
0
0
>-
1-
(.)
g_l
<(
(.)
10
8
J: s:6 (.!)
0
0
0
>-
(.!)
~ 4 z w
2
1980
LEGEND:
D HYDROELECTRIC
l::f:::f:::f:::f::l COAL FIRED THERMAL
EZ] GAS FIRED THERMAL
• OIL FIRED THERMAL( NOT SHOWN ON ENERGY DIAGRAM
NOTE : RESULTS OBTAINED FROM
OGPS RUN L8J9
DEVIL CANYON
(400 MW)
WATANA-1 (400 MW)
EXISTING S COMMITTED
0~--~--------------------------------------------------------------~
1980 1990 2000
TIME
GENERATION SCENARIO WITH SUSITNA PLAN E 1.3
-MEDIUM LOAD FORECAST-
FIGURE
!"L 7Ll.
2010
8 JiiiJ
~
~ 2
0
0
0
>-1-
0
'(tl
4:
0
10
8
::r:
3:6 (9
0
0
0
>-
(9
~ 4 z w
2
715
1980 1990
LEGEND:
D HYDROELECTRIC
f:ffffl COAL FIRED THERMAL
Ell GAS FIRED THERMAL
2230
2000 2010
• OIL FIRED THERMAL( NOT SHOWN ON ENERGY DIAGRAM)
NOTE: RESULTS OBTAINED FROM
OGPS RUN L60 I
TOTAL DISPATCHED
ENERGY
VEE(400 MW)
HIGH DEVIL CANYON-I (400 MW)
EXISTING AND COMMITTED
0~--~--------------------------------------------------------------~
1980 1990 2000
TIME
GENERATION SCENARIO WITH SUSITNA PLAN E 2.3
-MEDIUM LOAD FORECAST-
FIGURE
8-75
2010
8.10 •.
3
~ 2
0
0
0
>-I-
()
ri:l
<!
()
10
8
I:
3 6
(!)
0
0
Q
>-
(!)
~4
z w
2
1980
LEGEND'
D HYDROELECTRIC
MfffJ COAL FIRED THERMAL
Ell GAS FIRED THERMAL
-OIL FIRED THERMAL (NOT SHOWN ON ENERGY DIAGR
NOTE: RESULTS OBTAINED FROM
OGPS RUN L607
TUNNEL(380 MW)
WATANA -I ( 400 M W)
EXISTING S COMMITTED
0~--~--------------------------------------------------------------~
1980 1990 2000
TIME
GENERATION SCENARIO WITH SUSITNA PLAN E3.1
-MEDIUM LOAD FORECAST-
FIGURE
2010
8.11 [ii]
1.6
~
2
0
0
0
1.2
I .8
>-
!::
(.)
<(
a..
<(
(.)
>-
<.!)
0:::
w z w
.4
8
6
4
2
1980 1990
LEGEND:
D HYDROELECTRIC
ltttt:l COAL FIRED THERMAL
D GAS FIRED THERMAL -NOTE: RESULTS OBTAINED FROM
OGPS RUN LC07
2000
DEVIL CANYON
(400MW)
WATANA (400 MW)
EXISTING 8t COMMITTED HYDRO
1272
2010
0~--_.--------------------------------------------------------------~
1980 1990 2000
TIME
GENERATION SCENARIO WITH SUSITNA PLAN E 1.5
-LOW LOAD FORECAST-
FIGURE
-77
2010
8.12.
3.5
3
?:
~
0 g 2
I
>-
1-
u
it
<(
Ul
:I:
?:
<..~
0
0
0
16
12
I 8
>-
(!) a:: w z w
4
1980 1990
LEGEND:
D HYDROELECTRIC
[JffJ COAL FIRED THERMAL
E] GAS FIRED THERMAL
1000
2000
-OIL FIRED THERMAL( NOT SHOWN ON ENERGY DIAGRAM)
NOTE: RESULTS OBTAINED FROM
OGPS RUN LA73
TOTAL DISPATCHED
ENE
1980 1990
TIME
2000
DEVIL CANYON
(400 MW)
WATANA-2 ( 400 MW)
2010
2010
GENERATION SCENAR 10 WITH SUSITNA PLAN E 1.3
HIGH LOAD FORECAST
FIGURE 8.13 [i]
8-78
ti
Ul
"-
z
z \100
0
l.i 1000
~ C-\00
.J w
800
ill. IG.OO 1-----··· ---······ -t~o I
~ l&oo ~-----------------------~~~~~~----------
:z
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/ ,
GE.NE.RAL ARRANG'E.ME.NT ~ ~ r~oo
ORIGI)..!Al.. GROUND
..J 1'200 w SCAt-E.: A
S E.CTlON A·A.
SCALE.: f!l.
LONGITUOINA.L SE.CTION TWRU ct_ OF OAM
SCAL-E.: B
!GOD
FINE FIL TEl< r
, G~UT GAL.U:.RY
'\-DRAIN
SECTION TJ-ti<U DAM
SCALE; B
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C.HAINA.GE. IN F£E.T
POWER FACILHlES PROFILE.
SCALE: B
CHA.INAGE. IN FEET
SPILLWAY PROFILE
SCALE.~ B
EXISTING C\~L.Il'IO SURFACE.
ON RIGHT' 510£. OF SPILLWAY
PLATE
OEVtL CANYON
HYDRO DEVELOPMENT
FILL DAM
o.n OEC.I981
!
·~
-=-·
l
'2'!0:1 l
I
,--
GEN~RAL ARRANGEMENT
SCA.L.E.: A
ORIGINt...J... GI<OUND SURFACE.
-~
r CREST El.. '222.s''
, AT~ 0~ DAM
1-
Ill
IJl
b..
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7
0
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2100
'2000 -----
1900
1800
1700
1600
1500
14CO
______ .... __ ..... .-..----
SE.CTION A-A
SCALE.: C
"
LONGITUDtNAL SECTION THRU ¢l: OF DAM
SCA!..S1.e
1-
b)
IJl u.
~
z
0
~00
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2100
!2.000
1900
1800
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2'200
'2;100
:2000
1900
taoo
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IC.OO
1500
1400
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0 &CO
IN FEET
SCAt.£ A. 0 500 1000 FE.E'.T
S PI LUNAY PROF t L£.
. . . -· SCAl-E..: e
SCALE. f.:> 0 PLATE 2
WATANA
HYDRO DEVELOPMENT
FILL DAM
DMt DEC.I9BI
i
I
I
'l'lOO ------
210\')
'.SCALE. : P..,
........ ----------
LONGITUOINAL SECTION T\-IRU (j;. OF DAM
SCALE:&
NO !'<MAL MAX OPERATING
l.'E.VEL-E:L • .Z '2001
·~~
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:f1800
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Jooo
FE.E.T
SPILLWAY PROFILE.
NORMAl... MA'X.
2.100
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ti· !900
ul
I.L
2 ISOO
~rroo
~
:g1C600
lJl
cl1SOO
w.t... at.. 'l.O(X)'
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\ GAL-I...E~
\...__ Dl<A..It-.1
SECTlON THRU DAM
'.SCAt..E • e,
,. ,,4·UNI1' tNTAIG.E.
(STAG!;. JI)
......... ......
.._..,. _____ _
........... ,
POWE.R FACIU TlE.S PROFILE. I
SCALE: B
SCALE. A 0 SOO ICXX> FE.E.T -··· SCALE. e 0 .ZOO
PLATE 3
1 BIR ]~----ALA--SKA_. _Po_w_· .E_R_A_u_r_Ho ...... R_n_v___.
$U$1TNA li\'OIIOiU.ECTI!IC l'ftOJtC"f
WAr ANA
.STAGED FILL DAM
hi
Ill
tL
2
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0
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lil
~ •.
\ .
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SCA\.;e. ; A.
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CI<E5T E.L. 11""1'5'
AT rJ: OF' OAM
LONGlTUDt NAL SECTION T~ QU d; OF DAM
ti
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0
SECTION TI-II<U DAM
$C::ALE: C)
OTEEL LINER.
lN FEE'T
POWE.I<. FAClLfilE.S PROFILE
SCAL.IS.~ ~
SCAU:.A 0 400
··~
200 400 FiiE.T
GQOt.JNO 5l.IRFACE.
r"Z.· :24' OIA. CO~CICI:LTE. LINE.O
"TUl!.lloJE.LS
PLATE 4
OlJ1'L.eT SiRUCTURe
I
[iJ ALASKA POWER AUTHORITY ··~-----------------~ IIIli SUSITHI, lt'I'OROEt.ECTR•c t'RO.UCT
HIGH DEVIL CANYON
HYDRO DEVELOPMENT
D-'n DEC .1981 I----M...+----.;..,_ .. _________ -t----1r--t--t---i. ',;;.· ~; ~:/·~ 0.:: .~·.:.~ • J<!._;, 0PA~T¢1H't Oft.'\wtHO fifO.
t-:,...,.,,-1':-=+----------11=[1;:::!ld.IONS==------~----r.:,;:u:::,-t:m.=t •. -:::m=."'t::~~~+-,_.,-~-----t!,~:~~ .. cs·l L---------------------------------------------~~~~--------------------------"-------------------------------------------------------------------------~.2;_. _________ ,
'7.000 -----------
....-----.__-----'-,..·---~ '2100--..
/~-----·-·-·-~....---·-
'2.'200 ~...-UPPER RE.SE.RvoH~ LEVEL
tz.SOO
?.r;,OO .~~
\ .........._.
GE.N£QAL ARQANGEMENT
SCA.LE.: A.
I~CC
1800
s .. LoPe.~ ~cR.t..ST EL. '2*-01 i AT 'E OF OA.M
~~~------------~~--=~-----~-----------------------------
....... '~ -----__ ..... .. ~-..________ t. -----------...1'-----.......;... ____ =-""'-=---:-:-;;::; __ --------------·
LONG\TUDINA.L SECTION T~RU p OF DAM
SCALE-; B
NO~MAt. MA){ .V/,1.. ::.,..,---------·-------_-::;£·=·
1-.\0RMAL MAX, W.t.,,
SL,'Z.340 1
SE.CTJON T~R.U DAM
Q400r----------------+--------------~
POWER FACIUTES PROFILE.
NORMA.\.. MA.'It. W. t. .•
Et..'2~'
SCAt.E.:e,
sPU .. LWA'( CONTROL. SiRlJG'T.URE.
5· 551
" &5' WI-IE.Et. MOtJNTED GA'TE.$
!5 (0
CI4A.lN~G;. IN 1'-'Et::.T
SPILL\l.JAY PROFlLE.
~c.A.LC.: ~
IS
I
PLATE 5
'll!ltlii--AL_A_SKA--·-:-:-PO_W::-:-E"""":R':"':A~U7TH-:-O::-::R-:-:IT"::":Y---t:
ftllll} IUSITNA H'VOIIOIILI!CTIUC PROJECT
SUSITNA m
HYDRO DEVELOPMENT
""'" OEC.I981
I
I ___ j
SPILLWA."(~----
OlV~lOt-l
TU~NELS
<Z400
l-2.~
w
ul 2.2.00 u.
~ '2.100
z
0 2000 ~ ~ t<?IOO
~ .l$.00
GENERAL ARRANGEMENT
SCALE. • A.
CR,E.ST E.L "2 ~SO'
LONGITUDINAL SECTlON T~RU 4.. OF MAIN DAM
SCALE.#S
t;j
Ill u.
~
z
0
~ > uJ
.J
ul
'.Z.c:;oo
'ZSOO
'240o
'Z~OO
'2'2.00
'2.100
'2000
1900
1800
\
~OI..E.OA.M
l;j
111 u.
:?;
:z
0
~ ::> w
_J
Ill
2400
'2.500
2200
'2100
2000
1900
1eoo
1100
!GOO
NORMAl. MAX.
W.L..• E.!-. 2.~~ I
FINE Fli...Tit.R"' \ GROUT GAl-LER'(
\"'> GROUT CURTAIN ::;:o1 1 <:::::;:DRAIN
SEC-fiON "THRU MAIN DAM
POWER. FAC l LIT\ES Pl<OFILE.
'!!>C.A.l.-E. ~ e
SPILLVvAY PROF'tl.E.
SCALE: e.
SCALE.: &
sCALE. A 0
--.-~
SCA.t..E. 5 0 '200 · 4a:::> F'EE.T
PLATE 6
I··~~ 11---Al_A_SK_A_P_O_W_E-:-::R -:--A:"':"':UT:-:H:-::-0:-:-RI:-:-TY=-1
M [j S.USITNA HYDROELECTRIC I'ROJECT
VEE
HYDRO DEVELOPMENT
o~n DEC.I9SI
l
!
I I
i
l
' I
I I '
I
/
/\ ·'? I \
I
/
L-'2.500
'Z4So --/ '·-------
!
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/
/
/
;
I
MACLAREN
GE.NE.RAL ARRANGEMENT
SCALE; A
<Q~
.. ____ /
DAM CROSS SSCTtON
SGA.LE.tC.
SECTION A-A
CONCR.C.TE
SLAe.
SE.CTION C-C
'Z'2.00~------------------------~----~----------------------------------------------------------------------------
SECTION B-B
SCALE.: C
DENALI
G£NE.RA.L ARRANGE.M£NT
SCALE!A.
I /
l .I {',( .
~,.·
I )
\
\
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)
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25~L_ ____________ ~~~~~~~~~~~~~======~~==~~~~
\ ·-.,FIL.TER.
\SEMI· PE.I<,VIOt)S
DAM CQOSS SECTION
SCAL..£:'5
4· IG>'xo'Z1 W~E.E.I...
MOUNTE.O GAlES
SEC:::TION 0-D
SCALE: C.
SCAL.E. A 0 400 800 FS:E.T PLATE 7
I
I
I
--
llfllf 1~----A_LA_s_KA_P_o_w_e_R _A_u_TH_o_R_Irr_. ~
Mill S\JSITNA HYDIIOELECTRIC PAOJEC:"t
400 FE.E1 ---.-.. _._ .
SCAL.t: C 0 iOO ··--· DENALI a MACLAREN
HYDRO DEVELOPMENTS
SC'-!EME. ~ PLAN
ScA.Le 0 2 MIL.E. I ;
--...____1900--
1.400 ~
·=~ ------·-
_,-----··
.~· (--------__/ .
noo
,,,w..-. .... 40'Wli:SO'HIGH VERi'ICAL
LIFT GA"TE'S "----------~---------------........._ ·.. SPIL.LWAY Cl<E.'ST
.,..,___... t.:,.l4~5. ~-----
GE.NERAL ARRA~GI:.ME.NI
QE· RE.GULATION QA.M
SCA.L.E 0 300 GOO FEET . -...............
NOTE:,:
ALL. PLANS AND UYOUTS FOR
CONCEPTUAl.. STUDY Pti~SE$ ONI..'f,
~ENERAL ARRANG~MENT
.Qg\!IL CAN::tQN F=\::>WE'.R.J.~OUSE.
SCAI.E. 0 400 800 FEET
PLATE 8
118Hrt IJ--A_LA__;,__SKA_PO_W~E_R _AU_T_H_O~RilY~. -I
fill!j IUIITfiA H\'DftOI!I.I!CTI'IIC Pft0i.£l:'f'
PREFERRED TUNNEL
SCHEME 3
PLAN VIEWS
I
. 1100
~ 1!00
1100
'"00
1600
,_ .,. ....
d.
:5 1400
:z:
0
·~ > 1!00 UJ ... ....
l'l~
RE-REGULATION DAM TYPICAL SECTION
SCA.I...E.: A,
POWER TUNNEL INTAKE SECTION
NORMAL MAX.
.a.t47S' --·-
UNLINED
ScALE.: A
~W•40H Vi!ErtCAI...
I.! FT' c;.ATI\:5
SPiLLWAY PROFILE
f l A A
'--l~:lw&PNJ
CONC. LlNEO WISiEEL SET SE.CTION A·A
J;f;TAIL. A
!TrP.J
TYPICAL tUNNEL SECTIONS (t-.OTlo sc~<.t..E.)
... ... ...
d.
''oc
1500
1400
z laQO
:z:
0
._ l'lOO ~
"' ~ w
noo
1-
ll1
ll1
IL
~
z
0
~ 1~0
> UJ
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1000
IH=·~·-o . ---
. -----~ -----
SURGE. T.A-'11< ------
. -----l
1
I
I
ORIFICE.
------
OISTANCE. IN Mll...f!.S
TUNN.E.L ALIGNMENT.
-.......-......,~ -------------------------~
'~
~~0\b. TA.II-I<A.CE
,. TUNNEl-
" \
\ TAII.~AC:! S'!OI"~S.
NORM.\ I.
T.W.l..
El..B~~~=---i=~~~~~~==~~~ E~~· ~~~~~~::::::=~~==~-------------------------------~~~~---------:r-------------------~~~J---~~CcC~~i;R~~
i?ETAJL S.
(TYP.)
DEVIL CANYON POWER FACILITIES PROFILE'
DRILl.HOLE
l" OJA. ROO:EAI.T j
DETAIL "A.
HEX NUT
;GI<OUT AS .RE.QVI12£.D
I' (NP.)
"'
SCAt..!;;.: A
NOTE;
Al...t.. STRUCTURAl-AND St.JPPORT
DETAll.S ARE. CONCEPTUI\1.. AJ.JD
FoR. 'STUDY PURPOSE$ ONI..V.
SCAl-E A 0 roo.
PLATE 9
200 Fer::r
ROCK BOLTS ROCK BOLTS 4 SHOTCRETE
TYPICAL TUNNEL SECTIONS
(NOT TO SCAI..E) DE.TAlL "e), PREFE;~~EO TUNNEL
SCH~ME 3'
SECTIONS
9 -SUSITNA HYDROELECTRIC DEVELOPMENT
The studies discussed in previous sections of this report conclude that, on the
basis of the analyses to date, the future development of Railbelt electric power
generation sources should include a Susitna Hydroe1ectric·Project .. Further work
is required to fully establish the technical and economic feasibility of the
Susitna project and to refine its design. The project as currently conceived is
described in this section.
9.1 -Selected Plan
As described in Section 8, the selected Susitna Basin development plan involves
the construction of the Watana dam to a crest elevation of 2225 feet with a 400
MW powerhouse scheduled to commence operation by 1993. This date is the
earliest that a project of this magnitude can be brought on-line. A delay tn
this date would mean that additional thermal units \vould have to be brought
on-line resulting in an increase in the cost of power to the consumer. This
first stage would be followed by expanding the powerhouse capacity to 800 MW by
1996 and possibly the construction of a re-r-egulation dam downstream to allow
daily peaking operations. More detailed environmental studies are required to
confirm the requirement for this re ... regulation dam and it may be possible to
incorporate it in the Devil Canyon dam diversion facilities. The final stage
involves the construction of the Devil Canyon darn to a crest elevation of 1465
feet with an installed capacity of 400-MW by the year 2000.
'should the load growth occur at a lower rate than the current medium forecast)
then consideration should be given to-postponing the capacity expansion proposed
at Watana and the construction of the Oevi 1 Canyon dam to ··the year 2002 or pos-
sibly even 2005. These latter two dates correspond respectively to the 10\'l load
forecast and the extreme 1 0~1 forecast incorporating an increased 1 eve 1 of 1 oad .
management and conservation.. For actual load growth rates higher than the
medium 1 oad forecasts., construction of the De vi 1 Canyon dam caul d be advanced to
1998 •.
Although it has been determined that this deve 1 opment plan is extremely economic
for a wide range of possible future energy growth rates!) the actual scheduling
for the various stages should be continuously reassessed on, sayJ) a five year
basis. It should also be stressed that the dam heights and installed capacities
quoted above are essentially representative orders of magnitude at this stage of
project planning. These key parameters are subject to modification as the more
detailed project optimization studies are conducted during 198lo The darn type
selected for the Devi 1 Canyon dam site has currently been revised from the
rockfill alternative described in Section 8 to a thin double-curvature concrete
arch dam. More detailed engineering studies carried out subsequent to the
planning studies described have 'indicated this dam type to be more appropriate
to the site conditions as we11 as slightly more cost effective. The results of
these engineering studies are contained in Appendix H.
9.2 • Project Description
At this stage in the development of optimum project designs, various alternative
project layouts are .being produced for both 'the·. Watana and Devil Canyon sites.
These layouts are being compared from both technical and economic viE·Mpoints and
this comparison \'Jill 1ead to the selection o.f possibly two or three basic
layouts at each site for study in more detail.
9-1
At this early stage certain 1 ayouts are discerned to be more attractive than
their counterparts. Of these, a single layout i.lt each of the Watana and Devil
Canyon sites has been selected as representative of the possible final develop-
ment, and is described in this section. ·
These 1 ayouts are indicative of the present stage of the study. Much fie 1 d work
i'S still planned together with design and refinement studies, and these layouts
should on no account be regarded as the final developments at this time.
(a) Watana (Plates 12 and 13)
( i) ~ite Geologx
The dam site at Watana is underlain by a dioritic intrusion (pluton) .. -
The site has a favorab 1 e confi,gurati on because the river has cut down
through the intrusion, resulting in a narrow canyon. The pluton is
bounded at the upstream and downstream edges by sedimentary rocks
that show evidence of being deformed and arched upwards by the
plutonic intrusion (Figure 7.4}. The evidence to date indicates that
the sedimentary rock has been eroded from the top of the pluton at
the irrmediate site.. Follo'v"1ing intrusion, at intervals that have not
yet been determined, volcanics erupted into the area.. These
volcanics form the basalt flows exposed in the canyon near Fog Creek
downstream of the site, and the andesite flows over the pluton at the
dam site. There is no indication of basalt flows within the
immediate dam site, but the andesite has been detected in several
borings in the western portion of the site.. The nature and
characteristics of the diorite-andesite contact will be further
investigated in the 1981 program.
The surficial material at the dam site is predominantly talus and
very thin glacial sediments on the abutments, with limited deposits
·~of river alluvium and lake clay at isolated locations. The river
ch~nnel is filled with up to 80 feet of alluvial deposits derived
. from till and talus material. The drilling and seismic lines indi-
cate that the bedrock weathering averages ten to twenty feet, with a
very disti net gradation from weathered to unweathered rock. The sur-
ficial weathering processes seem to be primarily physical rather than
chemical. Bedrock quality below 60 feet is uniform to the maximum
depths drilled .. The pattern of sound, unweathered rock zones are
separated by shear zones of rock a 1 tered by injection of fe 1 site -and
andesite dikes, with subsequent deterioration of the broken rock by
groundwater. The basic conditions are favorable to construction of
both surface and underground structures, with remedial treatment
likely to·be limited to shear zones.
(ii) Geotechnical Aspects .,
The Watana dam site lies predominantly on sound diorite while some
portions of the downstream shell overlay andesite. The upper 10 to
40 feet of rock is weathered. The seismic considf'rations for the
site, as discussed in Section 7, indicate that the relatively uncom-
pacted alluvium (up to 80 feet in depth) would have to be removed ... from underneath most of the dam. In addition, it is a.ssumed that up"
9-2
to 40 feet of rock excavation wtll be required under the impervious
core and the supporting filters to found the dam on sound competent
rock. This type of fQundation preparation is considered narmal for
lar-ge dams of comparable size. Shear zones and joints within the
rock foundation have been 1 ocated and wi 11 require-consolidation and
curtain grouting. These. features may also necessitate the inclusion
of drainage features within the foundation and the abutments as indi-
cated in the present arrangement. Permafrost is present on the left
abutment and may a 1 so be present under the river cham1e 1. The data
indicater; that this is 11 warm 11 permafrost and can be economically
thawed for· grouting.
A deep relict channel exists on the right bank upstream of the dam.
The overburden within this relict channel contains a sequence of
glacial till and outwash interlayered with silts and clays of glacial
origin. The top of rock under the relict channel area v1ill be below
the reservoir level. Further investigations will be undertaken to
precisely define the characteristics of the channel.. However, the
data co 11 ected to date d0es not i nd:i cate that it wi 11 have any major
impact O!l the feasibility of the site.
The rock conditions. in the 1 eft bank, where the underground power-
house ·1 s currently proposed, are favorab 1 e, and the powerhouse cavern
will require only nominal support. However, additional investiga-
ticms will be conducted to determine the exact location and orienta-
tion of the features, so as to minimize the impact of joints and any
possible unfavorable stress orientation.
~4ateri a 1 s for construction of a fi 11 dam and re 1 ated concrete struc-
tures are-available within economic distances. Impervious and semi-
pervious core and filter materials are available within three miles
· upstream of the site, (Figure 7.4) and a good source of filter mater-
ial and concrete aggregate is available at the mouth of Tsusena Creek
just downstream of the dam. Rockfill is available from a quarry
source immediately adjacent to left abutment of the dam and from
structure excavations. There is also a possibility of using rounded
r·iverbed material for the dam shells if adequate quantities are
available. Further investigations will be conducted to better define
the quantity and characteristics of material in each source area and
the relative economics of each borrow location.
(iii) Dam
The main dam is an earth/rockfi11 structure with the majority of the
materials excavated from selected borrow areas, but v1ith a small
portion derived from excavation for the structures at the project
site. The compacted impervious till core is protected upstream and
downstream by gravel filter and transition zones and supported by
shells formed from compacted layers of blasted rock and gravel
materials. The maximum height of the dam above the foundation is
approximately 880 feet, the crest elevation is 2,225 f;set and the
developed crest length is 5400 feet.. The crest width is 80 feet, the
upstream and downstream slopes are 1:2.75 and 1:2 respectively and
the over a 11 volume of the dam is currently' estimated as approximately
63 million cubic yards~ The dam is founded on sound bedrock.
Upstream and downstream cofferdams ar0 founded on the river alluvium
and integrated with the mai-n dam.
A low lying area above the right abutment is closed with an approxim-
ately 25 foot high impervious fill saddle dam ..
(iv) Diversion
During construction, the river is diverted through two concrete-lined
tunnels driven within the rock of the left abutment. The tunnels are
set low and will flow full at all times. Upstream control structures
at the tunnel inlets will regulate flows to maintain a near constant
water level in the reservoir and allow formation of a stable ice
cover and to prevent ice buildup within the tunnel inlets. Control
will be affected by vertical fixed well gates housed within the up-
. stream structures. These wi 11 also be utilized for final closure
-together with mass concrete plugs constructed within the tunnels in
alignment with the dam grout curtain.
The river will be diverted upstream by means of a rock/earthfill
cofferdam founded on the riverbed alluvium.. Cutoff beneath the cof-
ferdam is formed by a slurry trench to rock.
( v) Spi 11 wa_y
The spillway is located on the right bank and designed to pass the
routed 1:10,000 year frequenc,y design flood of approximately 115,000
cfs without damage to any of the project structures. The spillway is
also capable of passing flows of up to 230~000 cfs corresponding to
the probably maximum flood at Watana. This would require a reservoir
surcharge up to 5 feet below the dam crest level. During passage of
this major flood some damage to the spillway chute and discharge
structures and scme downstream erosion within the river valley would
be accepted ..
The spillway consists of a gate structure, with three verti ca 1 fixed
wheel control gates, a concrete lined chute and a flip bucket, simi-
lar to that at Devil Canyon (Section 9.2(b)), discharging into a
downstream plunge pool excavated from the alluvium within the river-
oed ..
(vi} Power facilities
-Intake
The intake is situated upsb"eam of the right abutment of the dam.
It is set deep within the rock and is similar in structure to the
De. vi 1 Canyon intake with pro vision for drawing off water a.t differ-
ent ~evels within the fluctuating reservoir.
9-4
' '
f
-Penstocks
Four concrete-lined tunnel penstocks descend at an inclination of
55° and terminate in steel liners at the powerhouse feeding the
high pressure t~rbines.
-Powerhouse
The powerhouse complex is similar to that for Devil Canyon with
separate powerhouse and transformer bay caverns. The main cavern
houses four 200 MW turbine/generator units consisting of vertically
mounted Francis turbines driving overhead umbrella type generators
serviced by the main overhead crane. Major offices and the control
room are incorporated in the administration building at the
surface. An elevator descends from this building to provide
personnel access to the powerhouse. Vehicle access to the
powerhouse and transformer gallery is by unlined rock tunnel
leading from the bottom of the valley.
-Tailrace
The turbine draft tube tunnels lead from the powerhouse to a common
manifold supplying a single partly-lined tailrace tunnel which
emerges, below river level, downstream of the main dam.
(vii) Downstream Relf!ases
At the present time there is provision made for emergency drawdown of
the Watana reservoir. This vii 11 take the form of an i ntt~rmedi ate
level reservoir outlet~ Flows are controlled by high pressure gates
located in an underground chilmber, and a concr-ete-lined tunne 1
discharges into the diversion tunnel, downstr·eam of the concrete
plug. Small releases, during shutdown of the generating plant, are
made via a small diversion incorporated with the underground control
structure.
(b) Devil Canyon (Plates 10 and 11)
(i) Site Geology
Devil Canyon is a very nat'row V-shaped canyon cut through relatively
homogeneous argillite and graywacke. This rock was formed by low-
grade metamorphism of marine shales, mudstones, and clayey sand-
stones. The bedding strikes about 15~ northeast of the river align-
ment through the canyon and dips at about 65° to the southwest. The
rock has been deformed and moderately sheared by the northwest acting
regional tectonic forces~ causing shearing and jointing parallel to
this force (Figure 7.4). The glaciation of the past few million
years apparently preceded the erosion of the canyon by the river ..
Glacial deposits blanket the valley above the V-shaped canyon, while
deposits in the canyon i tse 1 f are limited to a 1 arge grave 1 bar just
upstream of the canyon entrance, and boulder and talus deposits at
the base of the canyon wa 11 s.
9-5
Bedrock conditions at Devil Canyon vary within a limited range due to
changes of lithology, but the rock is basically sound and fairly
durable. Jointing and shears ate frequently quite open at the
surface, but there is a general tightening of such openings with
depth. The major joint set strikes about North 30° West across the
canyon, and may be an indication of shear zones in this direction.
Twominor sets strike roughly North 60-90° East, with dips of about
50-60° south and 15° south. The orientation of the joints, and
particularly the shear z.ones, is not well defined. Further field
mapping in 1981 should clarify this.
(ii) Geotechnical Aspects
The Devil Canyon dam site lies on argillite and gray\'/acke exhibiting
significant jointing and frequent shear zones. The nature of the
rock is such that numerous zones of gouge, alteration, and fractured
rock were caused during the major tectonic events of the past, in
addition to the folding and internal slippage during lithification
and metamorphi~m. Consequently, zones of deep weathering and altera-
tion can be expected in the foundation. Excavation of up to 40 feet
of rock will expose sound foundation rock, and consolidation grouting
and dent~l excavation of badly crushed and altered rock will be nec-
essary to provide adequate bearing surfaces for the dam. Overburden
within the narrow V-section of the valley is minimal.
The left bank plateau, which is the location of a saddle dam, has a
buried rivei channel paralleling the river. The overburden reaches
90 feet under a small lake in this area and construction of the
saddle dam \-Jill require excavation of considerable amounts of till
and lake deposits or construction of a cutoff ex~ending down to
bedrock. Seepage cont~·~1 will be effected by two methods: first, by
general contact and ct.,nsc~ idation grouting to control flow at the dam
foundation contact, an~: second by a deep grout curtain ~lith
corresponding drainage curtain to limit downstream flow through the
.foundation. Permafrost has not been detected at the site but, if it
does exist, it is not expected to be substantial or widespread. A
thawing program can be incorporated in conjunction with the grouting
if necessary.
Construction materials are available in the large gravel bar immedi-
ately upstream of the dam site. The materials in this bar are .
estimated to be adequate in quantity for all material needs of the
concrete dam. The lakebed and till deposits in CheechakD Creek
(approximately 0.25 miles upstream), may be sources of a substantial
portion of impervious material for the earthfill saddle dam, ·
(iii) Dam
The main darn is curr.ently proposed as a thin cnncrete arch structure
with an overall height of 650 feet and developed crest length of
1,230 feet. The crest width is 20 feet and the base width at the
cr·own canti 1ever is 90 feet. The geometry of the arch corresponds to
a two center configuration which is compatib'le v1ith the assymetric
transverse profile of the valley.
9-6
The central section of the dam rests on a massive concrete plug~
founded deep within the valley floor and the upper arches terminate
in thrust blocks located high on the abutments. A concrete wall
extends 4 feet above the upstream edge of the crest to allow
additional surcharge during passage of the probable maximum flood • .
A low lying area on the left abutment is filled by a saddle dam. The
saddle dam is a rockfill structure with an impervious core. It abuts
and surrounds the concrete thrust block with the core wrapping the
concrete to provide a seal. Overburden wi 11 be excavated to all ow
the core to be founded on the deep underlying bedrocka
A continuous grout curtain and drainage system is provided beneath
the main and saddle dams linking with similar systems upstream-of the
powerhouse and beneath the main spilhoJay. Grout and drainage holes
are driven from a series of interconnecting shafts and galleries
which will allow continued access beneath the foundations of the
dam.,
(iv) Diversion
River diversion during construction is similar to diversion far
Watana with twin concrete-lined tunnels and upstream control
structures. Cofferdams are as described previously. Full use of
storage at Watana will be used to safeguard construction at De~il
Canyon.
( v) S pi 11 ways
The main service spillway is located on the right abutment and is
designed for flows of up to 90,000 cfs. Discharges are controlled by
three vertical fixed wheel gates housed in a concrete overflow struc-
ture incorporated in a right thrust block. Flows are routed down a
steeply inclined concrete lined chute, founded within sound bedrock,
and discharge over a flip bucket into the river. The flip bucket is
a massive concrete structure contiguous with the chutea It imparts a
vertical velocity component to the discharges, training them along a
uniformly curved invert and ejecting them in a broad shallow jet into
the river well downstream of the dam. Alluvium within the river is
removed to bedrock in the vicinity of the area of impact of the dis-
charge jet.
A secondary spi 11\rtay system designed to discharge 40,000 cfs is pro-
vided within the dam in the form of four submerged orifices high in
its center section. These orifices are controlled by 15 feet x 15
feet vertical lift gates and discharges are. thrown clear of the dam
into a downstream plunge pool excavated in the rock beneath the exis-
ting riverbed. '
The combination of the above spillways is sufficient to pass the
routed 1:10,000 year frequency design 'flood of 130,000 cfs. Greater
discharges are possible by allowing surcharge of the reservoir to the
1 eve 1 of the dam crest wave wall.
9-7
Beyond the rockfi11 saddle dam on the left abutment a channel is
excavated in the rock and runs approximately 1,400 feet downstream
discharging into a tributary valley to the main river. The channel
is closed by an impervious fill fuse plug which can be overtopped
during excessive floods and will wash out, probably after some local
excavation has been carried out, to the full section of the rock
channel.. Discharge down this channel plus surcharge over the main
spillways will allow for passing of the full probable maximum flood
in the unlikely event that this should ever take place.
(vi) Power Facilities
-Intake
The intake is located upstream of the right abutment of the dam.
It is a massive concrete structure set deep in the bedrock at the
end of a short upstream power canal.· The intake is formed of four
adjacent units, each with the capability of drawing off water at
levels throughout and below a 150 feet range of drawdown within the
reservoir. These levels are controlled by large vertical shutters
operating in t\<IO sets of guides set one behind the other. By rais-
ing and ·towering the shutter·s, openings can be created by varying
1 evel s over the height of the structure. These shutters wi 11 not
operate under pressure as closure of the intakes will be performed
by vertical fixed wheel gates set downstream of the shutters.
-Penstocks
Four concrete lined tunnel penstocks lead from the intake and des-
cend at an angle of inclination of 55° to horizontal to the under-
ground powerhouse. Just upstream of the powerhouse the 1 i ni ng
changes to steel in order to prevent seepage into the main power
cavern and to contain the high internal pressures in the vicinity
of the fractured rock caused by blasting the powerhouse excava-
tion.
-Powerhouse
The powerhouse complex consists of two main excavations; the main
power cavern housing the generating units service bay and mainten-
ance areas, and the transformer and draft tube gate gallery.
The main cavern houses four 100 MW turbine/generator units. The
turbines are vertically mounted Francis type units driving overhea<rl
umbrella type generators serviced by an overhead crane travelling
the length of the powerhall and end service bay. Switchgear, minor
offices, service areas and a workshop are housed in this area.
Upstteam bus duct galleries are inclined from generator floor level
at the power cavern to the transformer gallery running the length
of the powerhouse and set above the penstocks. Vertical shaft~ ure
r.~; sed from the draft tubes to the downstream side of the power-
h~:·use and these incorpor.ate vertical guides for the operation of
closure gates within the draft tubes and function as surge shafts
dur·iug changes of flow within t~e tailrace.
9-8
-.
Cable shafts rise from the transformer gallery to the surface and
the power lines are carried from these across the dam to t~e
switchyard on the left abutment. The control room and main
administration building is located at the surface.
Vehicle access to the powerhouse is via an inclined rock tunnel
driven from the bottom of the river gorge. Personnel access is by
means of an elevator operating between the powerhouse cavern and
the administration building.
-Tailrace
Downstream of the gates, the draft tubes merge into a single
concrete lined tailrace tunnel which will be set below river level·
and will flow full at all times.
(vii) Downstream Releases
Releases downstream during shutdown of the power plant will be made
through Howell Bunger valves set close to the base of the dam and
discharging freely into the river valley.
9.3 -Construction Sched~les
At this stage of the study, a preliminary assessment of the construction sched-
ules for the Watana and Devil Canyon dams has been made. The main objective has
been to provide a reasonable. estimate of on-line dates for the generation
planning studies described in Section 8. More detailed construction schedules
will be develnped during the 1981 studies.
In developing these preliminary schedules, roughly 70 major construction activi-
ties were identified and the applicable quantities such as excavation, borro\1/
and concrete volumes were determined. Construction durations were then estimat-
ed using historical records as backup and the expertise of senior scheduler-
planners, estimators and design staff. A critical path logic diagram was
developed from those activities and the project duration was determined. The
critical or near critica·f activity durations were further reviewed and refined
as needed. These construction logic diagrams are coded so that they may be
incorporated intoa computerized system for the more detailed studies to be con-
ducted during 1981. -
The schedules developed are described be.low:
(a) Watana Rockfill Dam
As shown in Figure 9.1, it i ~> expected to take approximately 11 years to
complete construction of the Watana dam from the start of an access road to
the testing and commissioning of all the generating units. Principal com-
ponents of the schedu 1 e inc 1 ude approximately 3. years of site and local
access, 1-1/2 years for river diversion and most of the remaining time for
foundation preparation and embankment placement. This period compares to
15 years estimated in the COE 1979 report. The most important differences
that the COE provided for a 4-1/2 year period of access road construction
prior to any work being done at the site. In this study, because of the
9-9
economic advantage to be gained from an early on-line date, a "fast tracku
approach has been adopted during the early stages of construction. This
i nvo 1 ves overland winter access and extensive aircraft support to the early
activities associated with construction of the diversion system and
abutment excavation for the main dam.
Only about six months per year can be used for fill placement due to snow
and temperature conditions. Fill placement rates have been estimated at
between 2.5 and 3.0 million cubic yards per month. This is somewhat higher
than the 1979 COE figure of 2.4 million cubic yards per month placement
over a five-month annual placement period. It has been judged ·that the
early on-line date would justify the implementation of construction systems
with higher production rates. It is expected that the river can be i m-
pounded as construction proceeds so as to minimize the time lag between the
completion of the dam embankment and the testing and. commissioning of the
first power unit.
The schedu 1 e shows the ear 1 i est date power production from the Watana dam
could start would be January 1993. This is based on starting construction
of access roads in early 1985 as soon as the FERC license \s received.
(b) Devil Canyon Thin Arch Dam
As shown in Figure 9.2, it will take approximately 9 years to complete the
_dam from the start of constructing access to the site to the testing and
commissioning of the power units. As far-as construction of the dam is
concerned this schedule agrees with that developed by the COE. It does,
however, incorporate an addition a 1 1-1/2 years for construction of a main
access road from the Watana site.
The key e 1 ements in determining the over a 11 schedu1 e are the construction
of diversion tunnels, cofferdams, the excavation and preparation of the
foundation and the p 1 acement of the concrete dam. For purposes of estimat-
ing activity durations, it is assumed that embankment and curtain grouting
will be done through vertical access shafts on each embankment.
(c) Interpretation of Schedules
The attached figures represent an 11 early start" schedule and the majority
of the study effort to date has been expended in determining the "critical
path 11 which controls project duration. During the continuing 1981 studies
the "non-critical" items will be scheduled to take into account resource
availability and financial and cl-imatic aspects. This will result in the
11 non-critica1u items being more rjgidly scheduled than is shown in the
attached figures.
9.4 -Operational Aspects
Section 8 outlines the results of the power and energy evaluations for the
selected plan. This section supplements. the information and illustrates some of
the monthly reservoir simulation results and highlights the downstream flow
characteristics which .are important from an environmental point of view.
9-10
Figures 9.3 through 9.5 illustrate the operation of the reservoirs for a typical
30 year period. Figure 9.1 shows the monthly energy production, inflow, out-
flows, and water levels for the Stage 1 Watana 400 MW development. Figures 9.4
and 9.5 illustrate similar results for the final fully developed two dam scheme.
The reservoirs have been assumed to be operated to produce monthly energy pro-
duction that follows the same general shape as the seasonal pattern of the total
Railbelt electricity demand. During the summer months, particularly during late
summer when the reservoirs tend to be full, additional or secondary energy is
generated in order to utilize some of the water that would otherwise be spilled.
The secondary energy production and spillage is clearly illustrated.
The figures indicate that during Stage 1 the Watana spillway would be operated 8
out of every 10 years and that in 7 of these years, flow would be discharged for
2 or more months. Once the total development is completed, the spillways would
only be operated for roughly 2-1/2 years out of 10 and most of the time for a
period of less than a month· in a given year. At this stage of development, the
Devi 1 Canyon spi 'ilway waul d be operated 7 out of 10 years, and during 3 of these
years spill would occur for 2 or more months.
Tables 9.1 to 9.3 summarize typical outflows from the downstream dam in the
preferred development. These flov1s include water coming from the turbines and
water passing over the spillway. It wi 11 be noted that dai 1 y fluctuations are
kept to a minimum for the Watana 400 MW development. Outflows from the Devil
Canyon dam in the fu11 development plan also show limited fluctuations.
However, for the Stage 2 400 MW capacity addition at Watana substantial daily
fluctuations do occur and may require downstream regulation.
9.5 -Environmental Review
The environmental input into the Susitna studies has two major components; miti-
gation planning and impact identification~ Mitigation planning includes avoid-
ance, reduction, and compensation. In participating in the Susitna development
selection, our objective was to identify what development scheme(s) was most en-
vironmentally compatable, thus, avoiding many potential impacts. In addition,
design features were recommended to reduce potential impacts even if the most
compatable sites were selected. Identifying compensation measures and the ac-
tual prediction of environmental impacts are the subject of ongoing studies.
The results of these studies will be included in our 1982 feasibility report to
be available prior to making the decision as to whether or not to proceed with
FERC licensing.
(a) Environmental Aspects
The Upper Susitna Basin has been considered as a potentia 1 hydroelectric
development site not only because of the economics and energy potential but
also because of its relative compatabi lity with the environment. Compared
to other potential large hydro development sites (e.g .. Rampart on the Yukon
Ri yer or Million Do 11 ar on the Copper River).. The Upper Susi tna has less
potential environmental impact. A ccmparison of alternatives to Susitna is
outside the realm of these studies, however, they are being fully assessed
in a parallel-study being conducted by Batelle.
9-11
As with any type of major development, hydroelectric projects can cause and
have elsewhere caused significan,t environmental impacts. In regard to re-
ducing or eliminating environmental impacts, probably the most important
factor is the selection of a development plan that is basically as inher-
ently compatible with the environment as possible. Retrofit type mitiga-
tion measures which are often of minimal success and usually very costly
are undesirable.
Development characteristics that have caused problems on other hydro pro-
jects that are not inherent to Susitna include:
-The diversion of major rivers.
-The direct blockage of anadromous fish migration due to the barrier
created by the dam.
The amplification of flow regulation problems caused by having a series
of reservoirs with minimal storage and poor spillway design.
-Inundation of large areas of prime wildlife habitat.
Thus, although the Susitna Hydroelectric Project still has the potential of
creating environmental impacts, many of the major potential impacts often
associated with hydroelectric developments are avoided bythe selection of
the Upper Susitna Basin. ~
'For studies within the Susitna Basin it is still important that environmen-
tal input sti 11 be provided into the decision making process. To date~ the
major envi ronmenta 1 imput into the Susitna studies has been directed to ...
\vards evaluation of alternatives, recommendation of design features, estab-
lishment of operating limits for planning purposes, and the collection of
baseline data. The major environmental objectives are to {1) ensure that
environmental compatibility is incorporated as a principle factor in devel-
opment selection and design~ and (2) to present a clear picture of the en-
vironmental consequences of developing the final selected scheme. Parts of
objective (1) are presented in this report where an environmental compari-
son of alternative Susitna developments is presented. The product of ob-
jective (2) will be contained in the environmental section of the feasibil-
ity report prepared at the end of Phase I studies.
It must be noted that although environmental compatibility has been incor-
porated as a desirable objective, it is not a sole factor in the decision
making process. The interrogation of economic viability, technical feasi-
bility, and environmental acceptability have necessitated judgements and
tradeoffs. To faci 1 it ate a ration a 1 assessment, these judgements and
tradeoffs have been defined as clearly as possible. In some instances,
economic and environmental preferences recommended similar action; an
ex amp 1 e being the Watana/Devi 1 Canyon p 1 an where the reservoirs are basic-
ally confined to the tiver valley. In other instances a specific decision
has been made that an economic expenditure is required to retain environ-
mental compatibility; examples being multi level intake structures to allow
for some temperature control of discharge water and the provision for down-.
stream daily _re-regulation of flows. In sti 11 other instances, the econom-
ic expenditure was not considered warranted to reduce or avoid resultant
9-12
environmental impacts; an example being a tunnel scheme at a cost c·f $680
million to avoid the inundation of the upstream portion of Devil Canyon.
As design studies progress, continued environmental impact assessments will
be incorporated. An environmental assessment of the selected scheme will
be incorporated into the fi naJ feasi bi 1 i ty report. This report wi 11 be
made available for government agency and public review prior to making a
decision as to whether or not to proceed with FERC license application ..
In 1975 (updated in 1979) the COE produced an En vi ronmenta 1 Impact State--
ment on the Watana/Devil Canyon Development. The information gathered by
the COE in this study is being enhanced by insight obtai ned from the 1980
studies and in areas where study effort is continuing as part of the pre-
sent study.
(b) .Hydrology
Under existing conditions seasonal variation of flows in the Susitna i_s ex-
treme. At Gold Creek the average winter and summer flows are 2,100 and
20,250 cfs respectively, a 1 to 10 ratio. With regulated discharge result-
ing from a hydroelectric development, downstream flows between Devil Canyon
and the confluence of the Talkeetna/Chulitna rivers will be relatively con-
stante Figures 9.3 -9.5 show the differences between inflows and outfiows
and the occurrence of spilling with the project at various stages of devel-
opment. These changes in flow will be attenuated downstream due to the un-
altered inflow from tributaries. Percent contribution from these tributary
streams under existing conditions is shown in Figure 7.5.
The monthly flow and resulting stage at Gold Creek, Sunshine and Susitna
Station with and \'li thout the project are shown in Figures 9.6 to 9 .a.
Under existing conditions the level of suspended sediment is very high in
the summer months (23 to 2620 ppm) and relatively low in the winter months
(4 to 228 ppm, ADF&G 1975). With the project, a glacial flow will result
year round wi.th suspended solids in the releases at Devi 1 Canyon Dam
.Projected to be in the 15-35 ppm range.
Changes in dissolved gasses, _specifically nitrogen, will be dependent on
the spillage occurrence and the design of the spillways. Although it is
considered that the majority.of potential_nitrogen supersaturation problems
can be avoided (or minimized) through design and operation, sufficient
study has yet to be conducted to confirm this.
Temperature of the discharge waters wi 11 be adjusted to approach the natur-
al river water temperatures through the incorporation of multilevel intake
structures. Even so, slight changes in discharge temperatures can be ex-
pected at certain times of the year, the extent to be predicted by means of
a reservoir computer model presently being developed.
Although it is essential to alter seasonal flows in order to produce ade-
quate power during the winter when the demand is highest, it is -possible to
avoid or dampen daily fluctuations in flow by means of operating the down-
stream powerhouse as a base load plant or incorporating a re-regulation
dam.. As thi,s constraint has been incorporated into the proposed Watana/
De vi 1 Canyon deve 1 opment, potentia 1 impacts associated with dai 1 y fl uctua-
tions due to peaking operations are avoided ..
"
(c) Mitigating Measures
In developing the detailed project design a range of mitigating measures
required to minimize the impact on the environment will be incorporated.
This is achieved by involving the environmental studies coordinator as a
member of the engineering design team. This procedure ensures constant
interaction between the engine~fs and_environmentalists and facilitates the
identification and design of all necessary mitigation measures.
There are two basic types of mitigation measures that are being developed:
Those which are incorporated in the project design and those which are in-
cluded in the reservoir operating rules. These are briefly discussed
below.
(i) Desi~n Features
The two major design features curr~ntly incorporated include multi-
level power intake structures to allow some temperature control of
released water and provision of a downstream re-regulation dam to
assist in damping the downstream discharge and water level fluctua-
tions induced by power peaking operations at the dam. During the
1981 studies these two features will be designed in more detail and
other features incorporated as necessary. Of parti{;Ular importance
will be the design of the spillways to minimize the impact of nitro-
gen supersaturation in the downstream river reaches. Consideration
will also be given to developing mitigation measures to limit the im-
pact on the environment during the project construction period. The
access roads, transmission lines, and construction and permanent camp
facilities will also be designed to incorporate mitigation measures
as required.
(ii) Operating Rules
. As outli.ned in Chapter 7, limitations on seasonal and daily reservoir
level drawdown, as well as on downstream minimum flow conditions:~
have been imposed. During 1981 more detailed studies will be under-
taken to refine these current constraints and to look at detailed op-
erational requirements to adequately control downstream water level
fluctuations, water temperature, and sediment concentration.
9-14
Month
JAN
FEB
MAR
APR
MAY
JUN
JUL
AUG
SEP
OCT
NOV
<.0 DEC
I
~
c.n
Note:
(1) Total
TABLE 9.1 -OUTFLOWS FROM WATANA/OEVIL CANYON DEVELOPMENT
STAGE 1 WATANA 400 MW
Average Outflow (cfs)
Monthly Average 1\vera9e Oa1I~
Inflow (cfs) Monthly Peak Off peak
1147 7699 7834 7603
971 7409 7538 7316
889 6758 6873 6676
1103 6168 6264 6100
10406 5689 5699 5682
23093 5571 5571 5571
20344 8227 8227 8227
18012 14263 14263 14263
10614 10299 10299 10298
4394 6503 6523 6498
1962 7497 7578 7439
1385 8237 8369 8143
outflow includes powerhouse flows, compensation flows and spills.
Average
Monthly
Spills (cfs)
1779
6582
2744
Month
JAN
FEB
MAR
APR
MAY
JUN
JUL
AUG
SEP
OCT
NOV
DEC
Note:
TABLE 9.2 -OUTFLOWS FROM WATANA/DEVIL CANYON DEVELOPMENT
STAGE 2 WATANA BOO MW
Average OUTFLOW (cfs) 1
Monthly Ave raga ;l!;verage IJa~I~
Inflow (cfs) Monthly Peak Off peak
1147 7699 15663 2011
971 7409 14979 2001
889 6758 13419 2000
1103 6168 12003 2000
10406 5689 10703 2108
23093 5571 10524 2033
20344 8227 11337 6006
18012 14263 15224 13576
10614 10299 12358 8827
4394 6503 12783 2017
1962 7497 15139 2039
1385 8237 16737 2166
(1) Total outflow includes powerhouse flows, compensation flows and spills.
Average
Monthly
Spills (cfs)
134
431
TABLE 9.3 -OUTFLOWS FROM WATANA/DEVIL ~ANYON DEVELOPMENT
STAGE 3 DEVIL CANYON 400 MW .
Month
JAN
FEB
MAR
APR
MAY
JUN
JUL
AUG
SEP
OCT
NOV
DEC
Notes:
Average
Monthly
Inflow (cfs)
8595
8280
7576
6988
8235
9294
9524
13534
11188
7838
8462
9211
Average
Monthly
Outflow (cfs)
8666
9216
7394
6833
7806
8796
8967
16239
13491
7950
8889
9383
Average
Monthly
Spills (cfs)
24
958
7129
4180
(1) Operated as a base load plant. Minimal daily flucbJations.
(2) Total outflow includes powerhouse flows, compensation flows
and spills.
9-17
~
1984 (985 1986 1987 1988 ~989 1990 1991 1992 1993 1994 1995 1996
YEAR -
' I 2 3 4 5 6 7 8 9 10 ·tr 12
"'
ACCESS TO SITE 3 PIONEER ROAD
MAIN
CONSTRUCTION ACCESS '
AT SITE
DIVERSION TUNNELS .
DEWATER ~ '
rEXCAVATION INSIDE CJFEROAMS/ FOUN
COFFERDAMS
EXCAVATE ABUTMENTS7 DATION PREPARA lON
I ./ 1 I FlLL PLACEMENT I
I, 2 r·-,..-... -I I
MAIN DAM ..
SERVICE SPILLWAY ....
-...
' ~
~
I INTAKES I
PENSTOCKS I ... I
POWERHOUSE 1
-·1
0
TAILRACE J
~ I
'
TURBINE/GENERATOR .,
INITIAL IMPOUNDMENT
UNIT I ONLINE r l UNIT 2. ONU 'IE UNIT30NU ~El 'UNIT4 :>NUNE
TEST AND COMMISSION --~ . .
I
LEGEND NOTES
CRITICAL ACTIVITIES I. MAIN DAM SCHEDULE BASED ON FILL PLACEMENT RATES OF 2.5 TO 3.0
OTHER ACTIVITIES MILLION CUBIC YARDS PER MONTH.
2. FIVE TO SIX MONTH FILL PLACEMENT SEASON ASSUMED.
KEY 3. BASED ON ACCESS FROM DENALI HIGHWAY AND ASSUMES OVERLAND
EARLIEST START OF ACTIVITY WINTER ACCESS AND AIRCRAFT SUPPORT DURING 1985. L . /EARLIEST FINISH OF ACTIVITY WATANA FlLL DAM fill ... fLATEST FINISH OF ACTIVITY
PRELIMINARY CONSTRUCTION SCHEDULE FIGURE 9.1 .
"
9-18
l
_l_
1992 1993 1994 1995 1996 t997 1998 1999 2000
YEAR
I 2 3 4 5 6 7 8 9
L -JWATANA VDEVIL CANYON ROAD
MAIN ACCESS TO SITE l ,--,
CONSTRUCTION PCCESS
AT SITE
DIVERSION TUNNELS "'
COFFERDAMS
. DEWATER J
EXCAVATION fNSlOE COFFERDAMS/
I EXCAVATE ABUtMEN~, FOUNDATION PREPARATION l
I -1 .. J-J ... MAIN DAM CONCRETE •I 2 -I I . .
MAIN DAM .. ~
-.
SERVICE SPILLWAY -
~
EMERGENCY SPILLWAY -"' _,
I
INTAKES a PENSTOC!:<S -
SADDLE DAM .. -
POWERHOUSE :..j -.
TAILRACE I
I
TURBINE GENERATOR I J ,.. -,
UNIT I ON LINE
UNIT 2 ONLiNE
INITIAL IMPOUNDMENT UNIT 3 ON LINE
1 H , +UNIT 4 ONLINE
TEST AND COMMISSION
:)
. '
LEGEND NOTES
CRITICAL ACTIVITIE.S L SCHEDULE ASSUMES DENAU-WATANA HI.GHWAY ALREADY AVAILABLE ..
OTHER ACTIVITIES 2. BASED UPON SlX MONTH CONCRETE PLACEMENT SEASON.
KEY
EAR L1 EST START OF ACTIVITY i /EARLIEST FINISH OF ACTIVITY DEVIL CANYON THIN ARCH DAM •• ;LATEST FlNISH OF ACTIVITY
--I. PRELIMINARY CONSTRUCTION SCHEDULE FIGURE 9.2,
9-19
~---~--~----~--------~-----~-----------------------
.-
0
*
::z: w
,.....
C/)
LLO u c:
........ 0
-:;: ('J
0
_..J
lL z (.')
0 ,___. ~
-
(
...s
~
.
~ n
fl I J~
lL.r u ~J
u ~ ~ 1 n n ru
1 1 ~ ,.! jl
I k u ~ ~ k l,_j 1\-~
AVERAGE MONTHLY ENERGY
j
n ~ ~
«
~ i~ ~ ~
fi·
~
ru ~ 11
~
I ~j n ;fll 1 Jl ll n [i
' ~ l J ~I ~ r l IL" iL., 1 ~ )~ u] 1 r1 I . r~ 1 ]
l t l l 1
~ ~ :L u ~
[L_ ~.._f !' ,,
ft. U' u l-1 ~ ~ ~ b b. L ~ k ~ r. . • r ... I<"" ' . r. r.r. C" .. r..,., r . . C" • . -. -o I '3,..~0 I 9,.~ I l 9;;2 I 9;;3 1 9:;4 19~:.> 19;.>6 19 .... 7 J 9;:>o 19.;9 19?0 s 961 1962 I 963 1 9'34 196.;:> 1966 1957 1968 1369 I 970 1 971 . l ~72 1973 t 97 4 1975 T97f? l 'J77 i 97b 197~
!"')
0
0
AVERAGE MONTHLY INFLOW
AVERAGE MONTHLY DISCHARGE
• (.:} t c: rrMAXI ~ U M EU VATION i
~0 ~ ~~ 1\ !~ fl\ {t\ ll\ !~ i ~J C1l~J 1\ f~ 11\ f 1\ (\II\ J 1\ J 1\ f\ f \ f ~ ;-~ n r\ fl\:f~ 1,\ i \ rl\ f i\ /I\ tl ~ ~ v v v "' lJ \J lJ 1J ~ iJ 1) u u "' 1J 'Ll lJ lJ "' v \ tl\ J \J I;J v \J \J \J ~ 'jJ I
<()4-~~--~~-+---4---~~--~--+-----+---~--~~-+---+--~-----~--r---+---~---r---+---+-t1~r~+-\.r. ~--+---4-~;-----r---r---T---~--_,,
>N ~· J& u..
.t~ ·---~--~~--+---~---+--~~--4---~--~-----+---~---+----~~~---r--~----+----r---+----i----4--+ ~.~ w<~~ -·~··~, ;
0 ~MI.· l N I MUM ELEVP!ftON Ji
0 I f .. 1 ' . I ~ 1'~50 t951 1952 1953 i954 1955 1956 1957 195S i959 19130 1961 1962 1963 i9?4 1965 1966 1967 1968 19~9 !970 i971 1972 1973 1974 1975 197? 1'.377 1975 1979
AVERAGE MONTHLY EL£VATION
NOTE : WATER YEAR OCT.-SEPT.
STAGE 1-WATANA RESERVOIR { 400 MW)
I
,
OPERATION OF THE WATANA I DtVIL CANYON DEVELOPMENT PLAN E 1.~
FIGURE 9.31111 I :
9-20.
-0 -
* C.')
C.) ..-. .
:C C) ::s-.:t
<!1
(f)
I..Lo
uC:
....... 0
3 (\J
0
_..J
~L z8 ,_ .
_, -~ n ..
.n fl. 1 J1
\_ ~ fl-1 ~J k
I
...
'
,.... n ~ 11 l n
~JI 1 1
.,_ ,J j1 I
u rl_ ~ ~ 1,_ k.l ~
AVERAGE MONTHLY ENERGY
I
11 -
~ ~
)
1 11 1n ~ 1 1 l ! u
l J ~ 1,_ ~ l ln L., l g ~l 1 r1 (1 l. l
t l 1 ,.... u ~l ll-\__ ~s L u IL-iL-\.... .... ~ "l_ u l ~ [1... it-IL---.
a 18.J0 19 .. d 19.J2 1:3~3 19.J4 195>.> 1955 1957 1958 1959 1960 1861 1962 1953 J954 1965 l96f; t967 1968 !9139 1970 a97l 1'3!2 1~)73 ,974 1375 I~FI3 1977 1976 tr79 r. -e_· .... C" • C" r. . . . . . .
!"'"\
0
*
0 ,..._.a
(J) •
LL.O u ("\)
w
-,---
I
-
~ ~
I !-"
l
r ....
~ N ~ ~
I
"
I I
«·•··-,-·~
:
r 1 r
~ ~ ~1 ~ ~ ~,
AVERAGE MONTHLY lNFLOW
"'-"'--··---r---· --~ ~--, -:-·-..... --r ~---r-" 1 ..... --HT·~··· -1 ~·-r-.... :r·-·-T~-·--r-· ---·-· -~--r---
i I I
.. _ SPII_LS -
n J n ~TURBINE n
~ ~ ~l ~ ~ ~ ~L ~ ~ ,...J ~~ ~ ~ ~ ~ ~ ~ ~ C) C::>
O:::a
<(' •
I o 19;,)0 l9 •. d 19~2. 19...~3 19;:>4 19..~~ 19~13 19.;7 t9..>S 19 .... 9 1960 t961 1952 1963 t964 196~ 1966 t967 ,968 1969 1970 197, 1372 197::5 1974 137~ !97? ,~.F7 l!Fo 1979 r: r· c: t" . c: c-r::: c: r-,_' c-. "' ' . c:" t ' • . c: '
(.)
tn AVERAGE MONTHLY DISCHARGE
~
0
NOTE: WATER YEAR OCT.-SEPT.
STAGE :5-WATANA RESERVOIR ( 800 MW)
OPERATION OF THE WATANA/ DEVIL CANYON DEVElOPMENT PLAN E l.3
FIGURE 9.4~~~~~~
9-21
·I
~-1
.... · ·,'i-
--------~---·;~-------------------------------------~----------~----~--------------~ .......
0
(') 0
.,...~ C:l
* " 0
(")
17\1
-30
C::J 0
-·! .-
Lt
..
-·
u-·• • ~
' t•
' I
n
I f
il
: r
A ~ j~L Nl ~~d
'
.. ---.
~ ~ [
r _[ 1
~vu r1 p~ J~~ rv ~-~ ri" ~J~J r~
.. -
AVERAGE MONTHLY ENERGY
-~
l ! I I l
--·-
-~" ····· .. ····--.. ·--· -,.
' . 1 I I
J r i -, J ~ :
_[ ... r-n a n n i
~~'\J ~~ ~J N ~u ~ f1j ~~ .t""\}1 ~~~'1 l~~ ~~ ]'-..,.ft-.-li~"'~-~,_,ll ~~--1,_ ~~ i~~ -'u
I
--
! . I >
"'t:' "'{'r: ;r._.._C_ (''~ • \ i:" r ("_· t r. . ..... r .. .-. ? r:: • . -. o ~~~o ~~~~ 1~~2 1~~3 ,9~4 19~5 19~6 19~7 t9ob 19~9 1960 t96t ,ss~ 196~ ,9B4 196~ 196~ 1967 .966 1969 1970 t071 1972 1973 t~74 1975 19?6 1977 1978 1979 J
I"")
0
-o
AVERAGE MONTHLY INFLOW
*0 l . .~---+--~~~+---~---+----r---+---~--~----~--~---r---;----+----r~-+----~--ti----+--~----+---~---+-7,--~--4----r--~----r---;---_,
0 t '<t .
Q
0 .
,....o
'-l.") .--'Ct'
LL . .--
'
AVERAGE MONTHLY DISCHARGE
~MAXI._ UM EU
.
-l
:VATIOl\ ' i
l I
~
tMINIMUM ELEVA:
..
ION
. I
1950 t951 1952 1953 1954 1955 1956 1957 1958 1959 .. 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 t971 1972 1'373 l974 1'975 .
AVERAGE MONTHLY ELEVATION
N 0 TE: WATER YEAR OCT.-SEPT. STAGE 3-DEVIL CANYON RESERVOIR (400 MW)
OPERATION OF THE WATANA/DEVIL CANYON DEVELOPMENT PLAN EL5
9-22 '\
i1 .................. _.,.1 --~--------------------------------------~~~--~~~--~' --~~~~~~
I
i
1975 19!7 1075 1979
FIGURE 9.5 flil
----~----
5 -· 11
4
I
I' ~ -l
~. m PF t:-. ·P~o~...::T
~s Cl J~o~ ~~ ~' ~S: lfi Er
5 l~ •
4 ·-
f.C>W£~·1t~ri) l
2
I l .
I .l ! T I
1 I I i -,
l I I
,Ill ! ~
1 i 1
-,
I ! l 1~i ~ '
4 I .J I ·i I 10
2 5 10 2~) 50
RETURN PERIOD, YEARS
DISCHARGE -STAGE FREQUENCY CURVE
SUSITNA RIVER AT GOLD CREEl<
NOTE~ BASED ·oN PRELIMINARY DATA)
SUBJECT TO REVISION 9-23 F1GURE
ro
··-....,
...
r
·-f~
··-u;.
-tl
i
t
..
9.Ji] .
-
4
-20
I"" 2 ~ ~ 19
~ H+~~~~~~~+H+H+H~A+~~~~T+++~',~~H+~H+~+-~~H+~+-~t8
~ H+HN~~~+H~~~+H~~~~:~~~+H*+~~~:~~ ~~~~)~·~~~}~~~~~!~8
~ "' I.L.. ~ H+HH**++rH+H~+H~~+H+H~~~H+H+~++~+-~+H~~~~~~~~~~I5i ~ ~ :r 5 t-H-W.W.;.t.H++-of-Ho++-i ....... o+H~...f.H~~-++-H+~++-Q.H+~+-+-+-+-...f..H-Hri~~+-+-+-~++H++:>I-+........_. 14 :I:
:!: I= .... w 09 E :z:
~. 8 w
~7 ~ x ~
<t 16
:E
5
4
_1_ l
I f
!
~ ¥
l . ~ .
!
'L
! i .l
1 I :
J t iiH+~++~-+-~~~~~~~-~~~~
to4 w.~~~.w~~~~~-~~~~~~~--~~--~~~ .. ~--~~~~~
2 5 to 25 so
RETURN PERIOD, YEARS
DISCHARGE-STAG.E FREQUENCY CURVE
SUSITNA RIVER AT SUSITNA STATION
NOTE.: BASED ON PRELl MARY DATA t
SUBJECT TO REVlSlON 9-24
FIGURE 9 .J ~~~
. ~l
:;
' ·'" .· ' ·~-·-' ~~.. ,__ . .._~, ... ·-. .., .. :~ . . . ·" .. ~ . ' " ,. ' ~ ' . ' .
--55!!D!--
6
5
4
3
2
~
.
, ..
5
4
3
2
4
10 !•
=
:JI~ ·-f1f 1.11:' • ...
~ ,
~
~ fF
!"~"" I"
~ ,.
II -I -!
•• &I
! ~ r-
i
I [.j !
! I!
l H i
2 5 10 25 50
RETURN PERIOD, YEARS
9~r C>J: ~~q ~5 ..
) ,~ 1.\1 t:. 'li1l
1-
'"""'II~ ~~ u...
......
~~~~tk~~fr, ¥Ois:
. & -·91~
s=~~ 156~
~5 • 5
t
I ,.
l ; ! •
I . ~ .
I
!
I
f
DISCHARGE-STAGE FREQUENCY CURVE
SUSITNA RIVER AT SUNSHINE
NOTE: BASED ON PREL1MINARY DATA
SUBJECT TO RETURN
9-25
FIGURE 9.811111·
\
\
'-.ALLUVIUM S>IOULD &.
DRE.OGE.D OUT 7
\
~
J
GENER.A.L ARRANGEMI:.NT
DATE
I
/
MAX. NORMAL OPERATING
LE.VE.L E.L. 1450'
so'
1500 .------1---
1400 1-----
ioOO
L.OCALIZE.D
CONCRETE LINING
%
\.
\
\
8
t{}
I
I
!
CUT· OFF TRENCH
SE.CTION A-A
FUSE Pl..UG
EL.l4~4 1
PLATE 10
ALASKA POWER Al,JTHORITY
SUSITNA HYDROELECTRIC PROJECT
DEVIL CANYON
SCHEME I
PLAN AND SECTION
"""DEC. 1981
MAX. NORMAL OPERATING -
LEVEL E.L. 14SQ' "4--)'-----j
I :;a::>
Ill<=
1200
CONCRE.TE. PL.UG
CROWN SE.CTIO N
1500 MAX NORMAL. OPE.RATINGl E.L ' u:vEL E.L. 14So' ~-l<!&_l
14= 1-----------------
1300
EL.l'lGS'
GROUT CURTAIN
1100
SERVICE. SPILL.WAY
APPROAC~ C~ANNE.L
ARC~ DAM
THRUST eLOCk
SECTION THRU POWER FACILITIES
1'1.00 1-------------------
1100
DIVE.RSION TUNNELS
7ooL·-----------------------------------------------
DAM PROFILE (L.OOK.ING UPSTRE.Alyl)
MAX. NORMAL. OPE.RA!"ING
E-L EL. 1450'
:...--.. ~~--
1..14Go'· FIXE.D W~EiJ.. GATES
ROCK
(T'(R) 1100 L_ ______________ -, _____ _
1000
SUIZFAC.! ( 12K?,~T ~IDE)
IAVG.TWL EL. 8':>0'
8oO l_ __________________________________________ -=~A~LU~VIUM 01ZE.04E.O OUT~
5ECTION Tl-IRU SPILLWAY
SCALE. 0 100 2.0:) FEET ~~iiiiiiiiij
DATE REVISIONS 01. N?, ȴ.
II
ALASKA POWER AUTHORITY ~~R II--,-U-S_I_T_N_A_H_Y_D_R_O:-:E:-:L-:E:-::C:-:T:-:R:-;1-;:-C--;:P-;;R-;;0-;J-;E;:-C:;T--a
DEVIL CANYON
SCHEME I
SECTIONS
.,n OEC.I981
-----~150
0
GENERAL ARRANGEMENT
CH.
zoo 4(X) FE.eT
12
ALASKA POWER AUTHORITY
SUSITNA HYDROELECTRIC PROJECT
WATANA
SCHEME 2
~ .. DEC.I98t
19CD
1800
1750
PRESSU12.E 'i2E..UE.F
DQAINS SPlLLWAY PROFILE
SCAL-E.: A
SECTION D-D
SCAl.E.' A 1&50
1800
1~50+------------------------------
SECTION E-E
1<:000
EXCAVATE ALL.UVIUM
1500 ~------------------------------------------------------------------------------------~~~~~~--~~~~~-----7~~1N RIVER BE.D
1450~----------------------------------------------------------------------------------------~~--~~--~~----------------
··-------.. --........ ..
1400L---------------------------------------------------------------------------------------------------------------------~-------------
'22.50
3 ·W'-'E.E.L MOUNTED GATES
-35 1 W )( 401l4 -------ORIGINAL GROUND~--------
SCALE.: A
Dl<AINAGE. GALI..E.RY
SECTION A-A SECTION B-B
SCALE 'A sCALE.: A
DATE
~' ~I ~I 4'
TYPICAL CHUTE WALL SECTION
SCALE: 13
SECTION C-C
Sct>LE.: A
REVISIONS
PLATE 13
ALASKA POWER AUTHORITY
SUSITNA HYDROELECTRIC PROJECT
WATANA
SCHEME 2
SECTIONS
om DEC.I981
1\
10 -CONCLUSIONS AND RECOMMENDATIONS
10.1 -Conclusions
(a) A standard methodology has been adopted to guide the Susitna Basin develop-
ment selection process described in this report. It incorporates a series
of screening steps and concludes with plan formulation and evaluation pro-
cedures.. Both the screening and plan evaluation procedures incorporate
criteria relating to' technical feasibility, environmental and socioeconomic
aspects, and economic viability.
{b) The economic analyses are required to assist the State in allocating funds
optimally and are therefore conducted using a real (i.e. inflation adjust-
ed) interest rate of 3 percent and a corresponding general inflation rate
of zero percent. Fuel costs are assumed to escalate at specified amounts
above the general inflation rate.
(c) Previous studies over the past 30 years have thoroughly investigated the
potential of the basin and the most recent studies conducted by the COE
have concluded that the Watana-Devil Canyon development plan is the prefer-
red option. However, review of these studies has indicated that a certain
amount of revision is appropriate, both to develop a more uniform level of
detail for all the alternative sites considered and to reassess the earlier
planning decisions in the light of current load projections which are
generally lower than those used in the earlier studies.
(d) The current {1980) Rai 1 be 1 t System annua 1 energy requirement is estimated
to be 2790 Gwh and the peak demand 515 MWo Near future demands can be sat-
isfied by the existing generating system plus the committed expansion at
Bradley Lake {hydroelectric) and the combined cycle {gas fired) plant at
Anchorage till 1993 provided an Anchorage-Fairbanks intertie of adequate
capacity is constructed.
(e) . Energy and capacity forecasts for the year 2010 can be summarized as in
Table 10.1.
(f) A range of technically feasible options capable of meeting future energy
and capacity demands have been identified and include the following:
-Thermal Units
• Coal fired steam generation: 100, 250, and 500 MW
• Combined cycle generation: 250 MW
• Gas turbine generation: 75 MW
• Diesel generation: 10 MW
-Hydroelectric Options
• Alternative development plans for the Susitna Basin capable of provid-
ing up to 1200 to 1400 MW capacity and an average energy yield of
approximately 6000 Gwh.
10-1
Ten additional potential hydroelectric developments located outside the
Susi to a Basin and ranging from 8 to 480 MW in capacity and 33 to 1925
Gwh annual energy yielda
{g) Indications are that the utilities will be subject to the prohibitions of
the Fue 1 Use Act and that the use of natura 1 gas in new faci 1 i ties wi 11 be
restricted to peak load application only.
(h) The Susitna Basin development selection studies indicated that the 1200 MW
Watana-Devi 1 Canyon dam ·scheme is the optimum basin development plan from
an economic, environmental, and social point of view. It involves a 880
feet high fill dam at Watana with an ultimate installed capacity of 800 MW
and a 675 feet high concrete arch dam at Devil Canyon with a 400 MW power-
house, and deve 1 ops appro xi mate l y, 91 percent of the tot a 1 basin potentia 1.
Should only one dam site be developed in the basin, then the High Devil
Canyon dam which develops 53 percent of the basin potential provides the
most economical energy. This project, however, is not compatible with the
Watana-Devil Canyon development plan as the site would be inundated by the
Devil Canyon development.
(i) Comparison of the Railbelt system generation scenario incorporating the
Watana-Devil Canyon Susitna development and the all thermal option reveals
that the scenario 11 with Susitna" is economically superior and reduces the
total system present worth cost by $2280 million. An overall evaluation of
these two scenarios based on economic, environmental, and social criteria
indicates that the "with Susitnau scenario is the pref~rred option.
The "with Susitna" scenario remains the most economic for a wide range load
forecast and parameters such as interest rate, fuel costs and fuel escala-
tion rates. For real interest rates above 8 percent or fuel escalation
rates below zero, the all thermal generating scenario becomes more econom-
ic. However, it is not likely that such high interest rates or low fuel
escalation rates would prevai 1 during the foreseeable future .
.
(j) Economic comparisons of the generating scenarios "with Susitna" and the
scenario incorporating alternative hydro options indicate that the present
worth cost of the 11 With SusitnaH scenario is $1190 million less. ·
(k) Preliminary engineering studies indicate that the preferred dam type at
Watana is a rockfi 11 alternative while a double curvature thin arch con-
crete dam is the most appropriate type for the Devi 1 Canyon site.
10.2 -Recommendations
The recommendations outlined in this section pertain to the continuing studies
under Task 6 Des.ign Development. It is assumed that the necessary hydrologic,
seismic, geotechnical, environmental, and tranmission system studies will also
continue to provide the necessary support data for completion of the Feasibility
Report.
Project planning and engineering studies should continue on the selected Susitna
Basin Watana-Devil Can .. von development plan. These studies should encompass the
following: c
10-2.
(a) Project Plannin_g_
Additional optimization studies should. be conducted to define in more
detai 1 ~ the l~atana-Devi 1 Canyon deve 1 opment p 1 an. These studies should be
aimed at refining:
-Dam heights ~
-Installed capacities: as part of this task consideration should also be
given to locating the tailrace of the Devil Canyon powerhouse closer to
Portage Creek in order to make use of the additional head estimated to
amount to 55 feet.
-Reservoir operating rule curves
-Project scheduling and staging concepts: a more detailed analysis of the
staging concept should be undertaken. This should include are-
evaluation of the powerhouse stage sizes and the construction schedules.
In addition, an assessment should be made of the technical, environmental
and economic f easi bi 1 i ty of bringing the Devil Canyon dam and .powerhouse
online before the Wantana development. This may be an attractive
alternative from a scheduling point of view as it allows Susitna power to
be brought online at an earlier date due to the shorter construction
period associated with the Devil Canyon dam.
The general procedure established during this study for site selection and
plan formulation as outlined in Appendix A should be adhered to in under-.
taking the above optimization studies.
(b) Project Engineering Studies
The engineering studies outlined in Subtasks 6~07 through 6.31 should con-
tinue as originally plahned in order to finalize the project general
arrangements and details, and to firm up technical feasibility of the pro-
posed development.
(c) Generation Planning
As outlined in the original Task 6.37 study effort~ the generation scenario
planning studies should be refined once the more definitive project data is
obtained from the studies outlined in Sections (a) and (b) above and the
Railbelt generation alternatives study is completed. The objective of
these studies should be to refine the assessment of the economic, environ-
mental, and social feasibility of the prorosed Susitna Basin development.
10-3
TABLE 10.1 -ENERGY AND CAPACITY FORECASTS fOR 2010
load Growth
Very low {i.e. incorporating additional
load management and conservation
measures)
low
Medium
I
High
10-4
Project Annual Energy Demand
Gwh
5,200
6,220
8,940
15,930
Equivalent
Annual Rate
of Increase
2.1~0
2.7%
4.1"l%
Peak
Demand
MW
920
1,140
1,635
2~,90f)