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ITNA HYDROELECTRIC PROJECT
DEVELOPMENT SElECTION R&PORT
KA
TASK 6 : DESIGN DEVELOPMJ!NT
SECOND DRAFT
JUNE 1·9'81
ER AUT
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ALASKA PQyfER AlJrHORITY
SUSITW\ HYDROELECTRIC PROJECT
RECEIVED
~KA POWLK AUihORilY
TASK 6 -DEVELOP!'1HIT SELECT ION
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.·· .ARLIS .
Alaska Resources Library & InfonmitionSelvices · ·
Library Builui ng; Suite 111 · ·
3211 Providence Drive
Anchorage, AK 99508-4614
SuTITASK 6. 05
DEV8..0Pr'ENT SELECTION REPORT
SECOND DRAFT
JUNE 1981
ACRES AMERICAN INCORPORATED
1000 Liberty Bank Building
Main at Court
Buffalo, New York 14202
Telephone: (716) 853-7525
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ALASKA POWER AUTHORITY
SUSITNA HYDROELECTRIC PROJECT
SUSITNA BASIN DEVELOPMENT SELECTION
VOLUME I -MAIN REPORT
TABLE OF CONTENTS
~a~
LISTOFTABLES ........................................................... iii
LIST OF FIGURES......................................................... vii
1 -INTRODUCTION
1 . 1 -The Study Area. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-l
1.2 -Project Description........................................... ·1-2
1.3-Objectives and Scope o~ 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 ................................ , ............... .
2.2-Previous Studies ............................................. .
2.3 Rai lbe1t Load Forecasts ...................................... .
2.4 Railbelt System and Future Power Generating Options .......... .
2.5 Susitna Basin ... , ............................................. .
2.6 Susitna Basin Development Selection .......................... .
2. 7 Susitna Hydroelectric Development ............................ .
2.8 Conclusions and Recommendations .............................. .
3 -SCOPE OF WORK
3.1 -Development Selection Studies................................. 3-1
3.2-Continued Engineering Studies ................................. 3-3
4 -PREVIOUS STUDIES
4.1 -Ear1y 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 .. il •••••••• ~ .. ll." ~ ~ 8 ...... £. ~. 4-2
4.5 -Ka~ser P~·oposal for Development .................... ,.......... 4-2
4.6 -U.S. Army Corps of Engineer'S -1975 and 19'79 Studies ......... , 4-3
5 -RAILBELT LOAD FORECASTS
5.1 -Introduction ........................................... -...... 5-1
5. 2 -El ectri city Demand Profi1 es........ . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2
5.3-ISER Electricity Consumption Forecasts ........................ 5-2
5.4-Past Projections of Railbe1t 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 Gene·ation Planning Studies ........... 5-9
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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-Thermai Options............................................... 6-7
6.6-Impact of the Fuel Use Act.................................... 6-12
6. 7 -Other Options. . • . . . • . . • • . . . • . • • . • • . . . • . . • . . . . . . . . . . . • . . . . . . . . . 6-14
7 -SUSITNA BASIN
7.1 -Introduction .•.........................•......................
7. 2 -Climatology and Hydrology ..•....••...............••...........
7.3 -Regional Geology ..•........•.•..•.•............•.•....•.......
7.4-Seismic Aspects ••....••••..•....•......•......................
7. 5 -Env i ronmenta 1 Aspects ••......••..•..............•.........•...
8 -SUSITNA BASIN DEVELOPMENT SELECTION
8.1 -Terminology ...•.•.••••.••...........•....••.••......•....•....
8.2 -Plan Formulat·ion and Selection Methodology .................. ..
8. 3 -Dam Site Selection .....•..•...•..•...•.••.............•.....••
8.4 -Site Screening ••.••...••.••.•••...•..•...•........••.••..••...
8.5-Engineering Layout and Cost Studies ....•.....•.....•.•........
8.6-Formulation of Susitna Basin Development Plans ..•.............
8. 7 -Evaluation of Basin Development Plans ....................... ..
8.8 -Comparison of Generation Scenarios With and Without the
Susitna Basin Development Plan ..•............•....•...........
9 -SUSITNA HYDROELECTRIC DEVELOPMENT
9. 1 -Se 1 ected P 1 an •..•.•••••••.•.••.•••..•..••.•..••••••.•.•.••••..
9. 2 -Project Description •••••.••.•.•••.•••..•..•.•.••... ,, .••....••.
9.3-Construction Schedules ••••.••.........•..........•.••.......••
9.4-Operational Aspects .......................................... .
9. 5 -En vi ronmenta 1 Review ••.••.••.•••••...•. , ..•.•.•.....•......•.•
10 -CONCLUSIONS AND RECOMMENDATIONS
10.1 -Conclusions •••.••.•.••••••.•.•.•••...•••........••......•....
10.2 -Recommendations ....•.•••...•...•....••...•..•••...•.•..•.....
BIBLIOGRAPHY
APPENDIX A -GENERIC PLAN FORMULATION AND SELECTION METHODOLOGY
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7-1
7-1
7-4
7-6
7-9
8-l
8-1
8-2
8-4
8-5
8-12
8-19
8-29
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9-1
9-9
9-10
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10-1
10-2
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I LIST OF TABLES
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Number
5. 1
5.2
5.3
5.4
5.5
5.6
5.7
5.8
5.9
5.10
6. 1
6.2
6.3
6.4
6.5
6.6
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
Railbe1t Electricity End-·Use Consumption (GWh) 5-15
Base Case Forecast (MES-GM}l (GWh) ............... 5-16
Summary of Rai1belt Electricity Projections ...... 5-17
Summary of Recent Projections of Railbelt
Electric Power Requirements ( GWh)... . . . . . . . . . . . . . 5-18
Performance of Past Projections Railbelt
Electric Power Requirements. . . . . . . . . . . . . . . . . . . . . . 5-19
Forecast Total Generation "r.d Peak Loads -
Total Railbelt Region ............................ 5-20
?ailbelt Region Load and Energy Forecasts Used
For Generation Planning Studies .................. 5-21
Total Generating Capacity Within The Rai1belt
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
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LIST OF TABLES (Cont.)
Number
7. l
7.2
7.3
7.4
7.5
7.6
7.7
8.1
8.2
8.3
8.4
8.5
8.6
8.7
8.8
8.9
8.10
Title
Summary of Climatological Data ................ . 7-18
Recorded Air Temperatures At Talkeetna
And Summit In oF. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-19
Maximum Recorded Ice Thickness On The
Sus i tna River. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-20
Average Annual And Monthly Flow At Gage
In The Susitna dasin. .. .... .. ........ ...... .. .. 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
Potential Hydroelectric Development............ 8-32
Cost Comparisons............................... 8-33
Dam Crest And Full Supply Levels............... 8-34
Capital Cost Estimate Summaries Susitna
Basin Dam Schemes Cost In $Million 1980.. .. .. .. 8-35
Results of Screening Model..................... 8-36
Information On The Devil Canyon Dam And
Tunnel Schemes................................. 8-37
Devil Canyon Tunnel Schemes Costs, Power
Output And Average Annual Energy............... 8-38
Capital Cost Estimate Summaries Tunnel
Schemes Costs In $Million 1980................. 8-39
Sus itna Deve 1 opment Plans.. . . . . . . . . . . . . . . . . . . . . 8-40
Energy Simulation Sensitivity.................. 8-43
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LIST OF TABLES (Cont.)
Number
8 0 i 1
8.12
8.13
8. 14
8 0 15
8.16
8.17
8.18
8.19
8.20
8.21
8.22
8.23
8.24
Title
Susitna Environmental Development Plans ......... .
Annua 1 Fixed Carrying Charges ................... .
Results of Economic Analyses of Susitna Plans -
Medium Load Forecast ............................ .
Results of Economic Analyses of Susitna Plans -
Low And High Load Forecast ...................... .
Results Of Economic Sensitivity Analyses For
Generation Scenario Incorporating Susitna Basin
Development Plan l .3-Medium Forecast .......... .
Economic Backup Data For Evaluation Of Plans .... .
Economic Evaluation of Devil Canyon Dam And
Tunnel Schemes And Watana/ Devi1 Canyon And
High Devil Canyon/Vee Plans ..................... .
Environmental Evaluation of Devil Canyon Dam
And Tunnel Scheme ............................... .
Social Evaluation of Susitna Basin Development
Schemes I P 1 ans ................................... .
Energy Contribution Evaluation Of The Devil
Canyon Dam And Tunnel Schemes ................... .
Overall Evaluation Of Tunnel Scheme And Devil
Canyon Dam Scheme ............................... .
Environmental Evaluation of Watana/Devil Canyon
And High Devil Canyon/Vee Development Plans ..... .
Energy Contribution Evaluation of the Watana/
Devil Canyon And High Devil Canyon/Vee Plans .....
Overall Evaluation Of The High Devil Canyon/
Vee And Watana/Devil Canyon Dam Plans ........... .
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8-44
8-4·7
8-49
8-50
8-51
8-52
8-53
8-54
8-55
8-56
8-57
8-58
8-60
8-61
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LIST OF TABLES (Cont.)
Number
8.25
8.26
8.27
8.28
8.29
9. 1
9.2
9.3
1 0. 1
Title Pag~
Results of Economic Analyses For Generation
Scenario Incorporating Thermal Development
Plan-Medium Forecast.......................... 8-62
Economic Sensitivity Of Comparison Of Generation
Plan With Watana/Devil Canyon And The All Thennal
Plan. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-63 .
Social Comparison Of System Generation Plan
With Watana/Devil Canyon And The All Thermal
Plan ............................................ 8-64
Generic Comparison Of Environmental Impacts
Of A Susitna Basin Hydro Development Versus
Coal Fired Thermal Generation In The Beluga
Coal Fields ..................................... 8-65
Overall Evaluation Of All Thermal Generation
Plans With The Generation Plan Incorporating
Watana/Devi l Canyon Dams. . . . . . . . . . . . . . . . . . . . . . . . 8-66
Outflows From Watana/Devil Canyon Development
Stage 1 Watana 400 MW. ............ ... ...... ..... 9-15
Outflows From Watana/Devil Canyon Development
Stage 2 Watana 800 MW........................... 9-16
Outflows From Watana/Devi1 Canyon Dev~lopment
Stage 3 De vi 1 Canyon 400 MW. . . . . . . . . . . . . . . . . . . . . 9-17
Energy And Capacity Forecasts For 2010 .......... 10-4
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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
Title Page
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
Fm·mul ati on Of Plans Incorporati n9 Non-Sus itna
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 Go 1 d C reek . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-2 7
Regional Geology................................. 7-28
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LIST OF FIGURES (Con~
Number
7.5
7.6
7.7
8. 1
8.2
8.3
8.4
8.5
8.6
8.7
8.8
8.9
8.10
8.11
8.12
8.13
9.1
Title
Relative Densities Of Moose -
November, 1980 ............. _ ............... . 7-29
Winter Distribution of Moose -March, 1980 7-30
Location And Territorial Boundaries of Wolf
Packs -1980................................ 7-31
Susitna Basin Plan Formulation And Selection
Process. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-67
Profile Through Alternative Sites ........... 8-68
Mutually Exclusive Development Alternativ~s. 8-69
Damsite Cost vs Reservoir Storage Curves .... 8-70
Damsite Cost vs Reservoir Storage Curves .... 8-71
Damsite Cost vs Reservoir Storage Curves .... 8-72
Schematic Representation of Conceptual
Tunnel Schemes.............................. 8-73
Capital Cost Versus Energy Plots Fo~
Environmental Susitna Basin Plans ........... 8-74
Generation Scenario With Susitna Plan El.3
-Medium Load Forecast -.. .. .. .. .. . .. . . .. .. 8-75
Generation Scenario With Susitna Plan E2.3
-Medium Load Forecast-................... 8-76
Generation Scenario With Susitna Plan E3.1
-Medium Load Forecast-................... 8-77
Generation Scenario With Susitna Plan El .5
-Low Load Forecast-...................... 8-78
Generation Scenario With Susitna Plan El.3
-High Load Forecast-...................... 8-79
Watana Fill Dam Preliminary Construction
Schedule .................................... 9-18
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LIST OF FIGURES (Cont.).
Numbe:r
9.2
9.3
9.4
9.5
9.6
9.7
9.8
Title Page
Devil Canyon Thin Arch Dam Preliminary
Construction Schedule ......................... 9-19
Stage 1 -Watana Reservoir (400 MW) Operation
of the Watana/Devil Canyon Development
P1an El. 3 .................................... " 9-20
Stage 3 -Wat~na Reservoir (800 MW) Operation
of the Watana/Oevil Canyon Development
Plan El. 3..................................... 9-·21
Stage 3 -Devil Canyon Reservoir {400 MW)
Operation of the Watana/Devil Canyon
Development Plan £1.3 ......................... 9-22
Discharge -Stage Frequency Curve Susitna
River 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
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PST QI PLATES
Number· --
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7
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9
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13
Tit1e -
Devil Canyon Hydro Development Fi'll Dam ........ .
Wa tana Hydt·o Deve 1 opment F i 11 Dam .............. .
Watana Staged Fill Dam ......................... .
High Devil Canyon Hydro Development ............ .
Sus i tna II I Hydro Deve 1 opment .................. .
Vee Hydro Deve 1 opment. . . . . . . • . . . .......••.....•
Denali & Maclaren Hydro Development: ........... .
Preferred Tunnel Scheme 3 Plan Views ........... .
Preferred Tunnel Scheme 3 Sections ............. .
Devil Canyon Scheme Plan and Section ......... .
Devil Canyon Scheme 1 Sections ................. .
Wa tan a Scheme 2 ................................ .
Watana Scheme 2 Sections ....................... .
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8.-80
8-81
8-82
8-83
8-84
8-85
3-86
8-87
8-88
9-26
9-27
9-28
9-29
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l INTRODUCTION
This report has been prepared by Acres American Incorporated (Acres) on behalf
of the Alaska Power Authority (APA). The report essentially represents a
milestone in the Plan of Study {POS) for the Susitna Hydroele~tric Project
currently being undertaken by Acres under the terms of an Agreement with APA
dated December 19, 1979. The Susitna POS was first \ssued 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 also addresses the requirements for filing a FERC license application
should project feasibility and en vi ronmenta 1 acceptability be estab 1 i shed.
Studies through March 1981 have mainly been concerned with e~·-.luation of the
need for electric power in the Alaska Railbelt Region and consider~tion 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 description of the study
area 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 soutn 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 walls 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 recognized 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 system, 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<~ 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 entirely of ground water Sl'pply and are generally free of sediment.
Freezeup starts in October io the upper reaches of the ba,;in, and by late
November ice covers have formed on al 1 but the most rapidly flowing stretches of
the river, Breakup generally occurs around early May.
The Susitna River and its tributaries 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
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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 Administration~ and the US Army Corps of Engineers (COE), as well as H.J.
Kaiser and Company. The more recent and most comprehensive of these jtudies
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 Devil Canyon. This development was found to be economically viable and
would provide the Rail~elt 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 Devi 1 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 seasona1 regulation of the
flow. Initially~ 400 MW of generating capacity would be installed at this site.
This w~uld 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-F~irbanks 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 rarks 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 calls for the first 400 MW at Watana to be an-line by 1993.
The additional 400 MW at Watana would be commissioned as required and probably
be brought on-line in 1996. The Devi 1 Canyon development would be brought
on-line in the year 2000.
1.3 -Objectives and Scope of Current Studies
The primary objectives of the studies are:
-To establish technical, economic, and financial feasibility of the Susitna
project to meet future power needs of the Rai lbelt region;
1-2
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-To evaluate the environmental consequences of designing and construct·ing the
Sus itna project;
File a completed license application with the Federal Regulatory Commission in
June 1982 •
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 by Acres with the support of
several subcontractors.
(a) Task 1 -Power Studies
These studies involve the development of a range of power and enerm' 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 site 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 Acres. Local aircraft companies are providing
fixed wing and helicopter support also under subcontract to Acres. A1so
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 dJta collection program being
conducted by R&M and associated office studies required for the project
which are being conducted jointly by R&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 ~egion and determining the seismic design criteria for
the structures to be built. Most of this work is being conducted by WCC
under subcontract to Acres.
(e) Task 5 -Geotechnical Exploration
This task incorporates all the g"~otechnical exploration fieid 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.
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(f)
(g)
(h)
( i )
( j)
(k)
Task 6 -Design Qevelopment
'
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 twc steges:
(i) Stage 1 -Develo~ment Selection
( i i )
This phase of the work encompasses the river basin planning and Rail-
belt system generation planning work aimed at determining the most
appropriate basin development plan.
Stage 2 -Feasibility Design
This phase includes the more detailed engineering studies aimed at
optimizing the selected project and producing the conceptual designs
for inclusion in the FERC license.
Task 7 -Environmental Studies
These studies encompass a broad range of field and office studies aimed at
determining potential environme~tal impacts due to the project and de-
veloping appropriate mitigating measures. 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 (AOF&G) under a reimbursable service
agreement with APA.
Task 8 -Transmission
This task includes the studies necessary to develop t.onceptual designs for
the transmission system required to convey Susitna power into the Railbelt
system. This work is being conducted by Acres with some support fro•n R.W.
Retherford and Associates {RWRA), a division of International Engineering
Company (IECO).
Task 9 -Construction Cost Estimate and Schedules
This work 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).
Task 10-Licensing
This task covers the work required to produce the FERC license documents
and is being carried out by Acres.
Task 11 -Marketing 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 secure the necessary funding for the project and are being carried out
by Acres with support f"om specialist consultants.
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(1) Task 12-Public Participation Program
APA is conducting an extensive public participation program to keep the
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 subcontractor~ support APA in
these activities on an as required bdsis.
(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 deve\lopment plans. Much emphasis is
being placed on consideration of every important perspective which may inf1uence
the se1ection of a particular co~rse 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 essentia1 component of this planning
process is a generalized multi-objective development selection 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) PlanninQ 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. 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).
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, 1 ess favorable
candidates are eliminated on the bas~s of economic, environmental, social
and other prescribed criteria. Plans are then formulated which incorporate
the shortlisted candidates individually 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 p1an.
Figure 1.2 i11ustrates this general process.
In the final evaluation, no attempt is made to quantify all 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 rf the planning process to
quickly focus on the key tradeoffs that effect the outcome of the deci-
sions. To facilitote this procedure, a paired comparison technique is used
so that at any one step in the planning process, only two plans are being
evaluated. ·
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The studies aimed at selecting the hest 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. T~vo Rai1belt 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 scenar1os is necessary to make a preliminary
assessment of the feasibility of the "with Susitna" 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 compressed 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 Sus'itna 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 princip.les:
(i) Intra-state transfer payments such as taxes and subsidies are
excluded;
(ii) 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 reflect 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;
( i 'ii) The ana lyses are conducted using "real" or i nfl at ion adjusted
parameters. This means that the interest or discount rate used equa 1 s
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;
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(iv) The major impact caused by the use of these inflation adjusted para-
meters is to improve the relative economics of capital intensive
projects (such as hydro generation) versus the high fuel consumption
projects (such as thermal generation}. It also leads to the selection
of larger economic optimum sizes of the capital intensive projects.
These shifts towards the capital intensive projects are consistent
with maximizing total benefits to the State.
1.5 -Organization 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 engineering studies aimed at
refining 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 status of technical support studies is in-
cluded in a separate volume of appendices. Tf1e report is organized as follows:
Volume 1 -Main Re£ort
Section 1: I ntrod uct ion
Section 2: Summa~
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 ,
this report.
Section 4: Previous Studies
This section brief:y 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 surmnari zed. It cone.: 1 udes 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.
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Section 7: Susitna Basin
This section p~·ovides a descript-ion o·f the physical attributes of the Susitna
Basin including climatologic, hydrologic, geologic, seismic, and environmental
aspects.
Section 8: Susitna Basin Development Se1ectio~
The Susitna Basin planning studies and the Railbelt system generation planning
work carried out are discussed in th·is section. It includes d description of
the Susitna Basin development selection process and preliminary assessment of
the economic and environmental feasibi1 ity of the selected Watana/Devil Canyon
hydropower development.
Section 9: Susitna Hydroelectric Development
This section describes. in more detail, the selected Watana/Oevil Canyon project
and includes a discussion of the results of the preliminary operational studies
and a summary environmental review of the project. The project general arrange-
ments described result from initial Task 6, Stage 2 engineering studies and
thereforr;~ present a more up-to-date picture than the arrangements described in
Section 8.
Section 10: Conclusions and Recommendations
In this section r-ecommendations are made for the Susitna Basin development plan
considP.red by Acres to merit further study. It also deals with tentative con-
clusions with respect to the pt·oject 1 s technical, P.nvironmental, and economic
feas i b i l ity.
Volume 2 -Appendices
A: Plan Formulation and Selection Process
A description of the generic approach to site scenarios, plan formulation and
plan evaluation is presented.
8: Thermal Generating Sources
This appendix outines the detailed backup to the 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 alternative hydro develop-
ments discussed in Section 6, i.e. those outside the Susitna Basin, are des-
cribed in this appendix.
D: Engineering Layout Design 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, Watana, Susitna III, Vee, Maclaren~ and Denali
sites.
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E; S~?itna Basin Screening Model
Here a description is presented of the computer model used to screen out
uneconomic basin development plans, as discussed in Section 8.
F: Sing 1 e and Multi-Reservoir Hydropower S.imulation Studie_?
The computer· model used to simulate the monthly energy yield from the various
Susitna devE~lopment plans is described in this appendix. Details are presented
on the average monthly firm and average yields for the deveiopment plans
discussed in Section 8 of the main report.
G: Systemw·ide Economic Evaluation {OGP5)
This append·ix contains the detailed backup information to the computer model
runs used in the economic evaluation of the various generating scenarios
considered 1n 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
gathe1~ed by Acres during the course of investigations and by the various
subcontractors.
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LOCATIOr~ MAP
LEGEND
\1 PROPOSED
DAM SITE$
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j
SCALE I !4 MILES
LOCATION MAP
FlGURE
l
DEFINE
OBJECTIVES
J
INPUT FROM AVAILABLE SOURCES -PREVIOUS AND CURRENT STUDIES
FEEDBACK
FEEDB.I\CK
-l
LEGEND
-1\ STEP NUMBER IN
4 STANDARD PROCESS
(APPENDIX A )
L PLAN FORMULATION AND SELECTION METHODOLOGY
----------------------------------~------------------------------------~----~F~IG~U~R~E21~.2~==~
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DEVELOPMENT OF AN A~L
THERMAL GENERATING PLAN
DEVELOPMENT OF AN OTHER
HYDRO GENERATING PLAN
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DEVELOPMENT OF A SUSITNA
BASIN GENERATING PLAN
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ALL
THERMAL
PLAN
OTHER
HYDRO
PLAN
SUSITNA
PLAN
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GENERATIN.G SCENARtO
LEGEND
PLANNING APPROACH
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APPUCAH?N OF PLAN
FORMULATION AND
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END PRODUCTS
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2 -SUMMARY
IN PREPARATION
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3 -SCOPE OF WORK
The Scope of Work discussed in this section of the Development Seletion Report
includes the development selection studies and preliminary engineering studies
aimed at refining the general arrangements of the selected Watana and Devil
Canyon dam projects.
Further details of the Scope of Work may be found in the Acres' POS _. __ ).
3.1 -DevE~lopm~nt Selection Studies
These studies constitute Stage 1 of the Task 6 design studies and include the
following:
(a) Review of Previous Studies and Reeort! (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 ( ) .
(b) :nvestigate Tunnel Alternatives (Subtask 6.02)
In this subtask conceptual engineering desiqns of a long power tunnel
alternative to the Devil Canyon dam are prodvced and evaluated in terms of
economic and environmental impact. This work is summarized in Section 8
and is reported in detai 1 in Reference ( ) .
(c) Evalu.:~.te Alternative Susitna Developmen!2_ (Subtask 6.03)
This subtask incorporates studies aimed at developing engineering~ cost 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
development 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
evaluc1te 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) Watana. and Devil Canyon Staged Development (Subtask 6.06)
As an extension to the engineering layout work described above, several
additional layout studies have been undertaken to investiqate the
feasibility of staging dam construction at the larger damsites such as
Watana and High Devi 1 Canyon. Consideration is also given to methods of
staging the mechanical equipment. The results of these studi~s are
included in Section 8.
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(e) Therma1~nerat·ing Reso.!-!!:~ (Subtask 6.32)
Economic benefits of proposed Susitna Basin developmer.,s are evaluated in
terms of the economic impact on the entire Rai lbelt electrical generating
system. It is therefore necessary to develop cost and performance figures
for alternative energy generating resourcP~ including thermal and other
potential hydro sites located outside the Susitna Basin. The subtask
involves studies undertaken to develop pBrformance 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) Hydro1~ric Generating Source (Subtask 6.33)
This subtask involves an extensive screening exercise incorporating
economic and environmental criteria. The aim of this exercise is to
shortl·ist several potential hydroelectric developments located outside the
Susitna Basin which could supply the railbelt with energy. Conceptual
sketch 1 ayouts are produced for thF short 1 i st developments in orde,~ 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)
(h)
This subtask includes the environmental studies necessary to screen the
potential hydroeiectric 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.
Load Manaqement and Conservation (Subtask 6.35)
In order to thoroughly assess the economics of the proposed Susitna
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 load management and conservation
scenario and appropriate adjustments are made to energy and load forecasts
for use in the generation planning studies discussed in Section 5.
(i) Gener..:ation P,!a~.n.ing_ (Subtasl<. 6.36)
This subtask involves the systemwide economic analyses undertaken to
determine the economic benefits of various Susitna Basin development plans
and a ltet~nat i ve a 11-therma i and therma 1-p l us-other-hydro generating
scenarios. These latter two scena~ios are studied in order to assess the
economic benefit associated with developing the Susitna Basin. A computer
generation planning model is used to undertake these analyses.
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Section 8 and Appendix G outline the results of this work.
(j) Development Selection Report (Subtask 6.05)
This subtask deals with the production of the report. It also includes a
summatry of the load projections prepared by ISER and the power projections
provided by WCC in Section 5.
Additional study work is also carried out to formalize the project
deve1opment 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 -f~inued Engineering Studi~s
As the development selection studies were finalized work continued on
engineering design studies aimed at refining the general arrangements at the
Devi 1 Canyon and Watana sites. These studies involve the production of
alternative general arrangements ·incorporating rockfill and concrete arch darns
at Watana and several alternative concrete arch dams at Oevi 1 Canyon. These
arrangements are casted and evaluated to determine which is the most
appropriate. Design work is carried out on the proposed thin arch dam at Oevi 1
Canyon to ensure that such a structure can safely withstand the anticipated
seismic loading. Extensive use is made of computer stress analysi~ techniques
in the design studies.
These studies are seeped in Subtasks 6.04, 6.07, and 6.08 and the results are
summarized in Section 9 and Appendix H.
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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 -Earlt Studies of Hydroelectric Potential
Shortly after World War II had ended, the USBR conducted an initial investiqa-
tion of hydroelectric potential in Alaska, reporting its results in 1948.
Responding to a recommendation in 1949 by the nineteenth Alaska territorial
legislature that Alaska be included in the Bureau of Reclamation program, the
Secretary of Inter1or provided funds to update the 1948 work. The resulting
report, issued in 1952, recognized the vast hydroelectric potential within the
territory and placed particular emphasis on the strategic location of the
Susitna River between Anchorage and Fairbanks as well as its proximity to the
connecting Rai lbelt (See Figures 1.1 and 4.1).
A series of studies were commi~sioned over the years to identify dam sites and
conduct geotechnical investigations. By 1961, the Department of the Interior
proposed authorization of a two d~n power system involving the Devil Canyon and
the Denali sites (Figure 4.1). The definitive 1961 report was 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 l950 1 S
and l960 1 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 for more than a decade .
The Rampart report was finally shelved in the eai·ly 1970's both because of
strong environmental concerns and uncertainty of marketing prospects for so much
er;ergy, particularly in light of abundant natural gas which had been discovered
and developed in Cook Inlet.
The energy crisis occasioned by the OPEC oi 1 boycott in 1973 provided some fur-
ther impetus for seeking development of renewable resources. Federal funding
was made available both to complete the Alaska Power Administration 1 S update re-
port on Susitna in 1974 and to launch a prefeasibi lity investigation by the
COE. The State of Alaska itc:;elf commissioned a reassessment of the Susitna
Project by the Henry J. Kaiser Company in 1974.
Whereas the ge~tation period for a possible Susitna Project has been long, Fed-
eral, State, and private organizations 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.
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4.2 -U.S. Bureau of Recla112.ation -1953 Stud.Y ( ___ )
The USBR 1952 report to the Congress on Alaska's overall hydroelectr·ic
potential was followed shortly by the first major study of the Susitna Basin in
1953. Ten dam sites wer~ identified above the railroad crossing at Gold Creek
{see also Figure 4-1): -
-Go 1 d Cr·eek
-Olson
-Dev i 1 Canyon
-Dev·i 1 Creek
-Watana
-Vee
-Maclaren
-Den.1 1 i
-Butte Creek
-Tyone (on the Tyone River)
Fifteen more sites were considered below Gold Creek, however more attention has
been focused over the years on the Upper Susitna Basin where the topography is
better suited to dam construction and where less impact on anadromous fisheries
is expected. Field reconnaissance served to eliminate half the or1ginal Upper
Basin list and further USSR consideration centered on Olson, Devil Canyon,
Watana, Vee and Denali. All of the USBR studies since 1953 have regarded these
sites as the most appropriate for further investigation.
4.3 -U.S. Bureau of Rec~amation -1961 Study{ __
In 1961, a more detailed feasibility study resulted in a recommended five stage
development plan to match the 1oad growth curve as it was then projected. Oevi 1
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 Oevi 1 Canyon
dam alone would not store enough water to permit higher capa.cities to be
economically installed since long periods of relatively low flow occur in the
winter months. The second staae would have increased storage capacity by
addition of an earthfill dam at Denali in the upper reaches of the basin.
Subsequent stages involved adding generating capacity to the Devi 1 Canyon dam.
Geotechnical investigations at Devi 1 Canyon were more thorough than at Denali.
At Denali, test pits were dug, but no drilling occwored.
4.4-Alaska Power Administration-1974 ( __ )
Little change from the basic USBR-1961 five stage concept appeared in the 1974
report by the Alaska Power Administration. This iater effort offered a more
sophisticated design, provided new cost and schedule estimates, and addressed
marketing, economics, and environmental considerations.
4.5 -Kaise~r Proposal for Development ( __ )
The Kaiser study, commissioned by the Office of the Governor in 1974, proposed
that the initial Susitna development consist of a single dam known as High Oevi 1
Canyon (See Figure 4.1). No field investigations were made to confirm the
technical feasibility of the High Devil Canyon loc.1.tian, as the funding leve1
was insufficient for such efforts. Visual observations suggested the site was
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probably fa1vorab 1 e. The USBR had always been uneasy about foundnt ion conditions
at Dena1i, but had 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 ac High Devil Canyon which, at
810 feet, would create a large enough reservoir to overcome the storage pr·oblem.
Although the selected sites were different, the COE reached a si1nilar 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 esti111ating 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 add"!tional
firm energy provided economic JUStification at some later date.
Kaiser did not regard the development of an energy consumptive aluminum plant as
necessary to economically justify its proposed project.
4.6 -U.S. Army Corps of Engineers -1975 and 1979 Studies __ , ___ _
The most comprehensive study of the Upper Susitna Gasin to date ·.-~as completed in
1975 by the COE. A total of 23 alternative developments were analyzed, includ-
ing those proposed by the USBR as ~vell as consideration of coal as the primary
energy source for Railbelt electrical needs. The COE agreed that an arch dam at
IJevil Canyon was appropriate, but found that a high daw at the L~atana site r-muld
form a large enough reservoir for seasonal storage and would permit continued
generation during low flow periods.
The COE recommended an earthfi 11 dam at Watana v1ith a height of 810 feet. In
the longer term, development of the Denali site remained a possibility vJhich, if
constructed, would increase the amount of firm energy available, even in very
dry years.
An ad-hoc t,:Isk force was 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 environmenta 1 and socioeconomic questions, ~Jev-e
necessary before any construction decision caul d be made.
At the Federal level, concern was expressed at the Office of 1-'lanagement and
Budget regarding the adequacy of geotechnical data at the Watana site as well as
the validity of the economics. The apparent ambitiousness of tr1e schedule and
the feasibillity of a thin arch dam at 1Jevi1 Canyon ~~ere 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 gravHy dam was analyzed as an alterna-
tive for the~ thin arch dam at Devil Canyon and the ~Jatana dam ~vas changed frorn
earthfill to rockfi11. Subsequent cost and schedule estimates still indicated
economic justification for the project.
4-3
LEGEND
TYONE & OAMSITE
5 0 5 15
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SCALE IN MILES
DAMS I TES PROPOSED SY OTHERS la~1n I
FIGURE 4.1 Ifill~~ 71
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5 -RAILBELT LOAD FORECASTS
5.1 -Introduction
The feasibility of a major hydr·oelectric project depends in par·t upon the extent
to 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 ther·efor·c par-
ticularly 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 proje~tions for the Alaska Railbelt region.
Section 5 presents a review of the economic scenarios ur0n which the ISER fore-
casts were based, and a discussion of the forecasts developed for use in gener-
ation planning studies.
5.2-Electrici~y Demand Profiles
This section reviews the historical growth of electricity consumption in the
Railbelt, comparing it to the national trend. Railbelt electricity consumption
is then disaggregated by regions and by eno-use sectors to clarify past usage
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 National 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 over time due to the gradu1l maturing of
the Alaskan ecunomy. Table 5.2 compares National and Alaskan growth rates
in the residential and commercial sectors. Growth in the Railbelt has ex-
ceeded the national average for two reasons. Firstly, population growth in
the Railbelt has been higher than the national rate. Secondly, the propor-
tion of Alaskan households served by electr-ic utilities was lower than the
United States average so that some growth in the number of customers occur-
red independently of population growth.
(b) Regional Demand
Electricity demand in the Railbelt, disaggregated by re3ions, is snown in
Table 5.3. During the period 1965 to 1978, f'·eater Anchorage account<;>t1 for
about 75 percent of Railbelt electricity consumption followed by Greater
Fairbanks with 24 percent and Glennallen-Valdez with 1 percent. The pat-
tern of regional sharing during this period has been quite stable ana no
discernable trend in regional shift has emerged. This is mainly a r·esult
of the uniform rate of economic development in the Alaskan Railbeit .
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(c) Enc~onsumetion
Railbelt electricity co11sumption by major end-use sector is shown in Table
5.4. In the residential sector, electricity consumption is largely attrib-
uted to space heating; while utilities such as refrigerators, water heat-
ers, lights and cooking ranges rank next in order of usage. In the commer-
cial-industrial-government sector, (Hid-use consumption is less clear·
because of a lack of data; however, it is reasonable to asswne that elec-
tricity is used mainly for lightiny, space heating, coo1itHj ancl v1ater heat-
ing. Consumptio~ in the miscellaneous sector is attribt1ted mainly to
street lighting and usage in second houres.
The distribution of electricity consur~tion in these end-use sectors has
been fairly stable. By 1978, the commercial-industrial-govermJent and tne
residential sectors accounted for 52 percent and 47 percent respectively.
In contrast. the 1978 nationwide shares were 65 percent and 34 percent res-
pectively(_).
5.3-rs~ _ _[lectricity Consumption Forecasts
As outlined in Section 3, the electricity consumption forecasts v1ere undertaken
by ISER( ). This section briefly discusses the methodology used !:ly ISEH to
estimate--electric energy sales for the Railbelt, and summarizes the results
obtained.
(a) ~1etl1odo 1 ogy
The ISER electricity demand forecastiny model conceptualized in computer
log·ic the linkaye between economic growth scenarios and electricity con-
surnpt ion. The output from ti1e model is in the form of projected va 1 ues of
electricity consumption for each of the three geographical areas of the
Railbelt (Greater Anchorage. Greater Fairbanks and Glennallen-Valdez) and
is c:1asslfied by fina1 use (i.e., heating, washing, cooling, etc.) and con-
suming sector {commercial, res1dential, etc). The model produces output on
a five-year time basis from 1985 to 2010, inclusive.
The ISER model consists of severdl submodels l1nk.ed by key variables aM
driven by policy and technical assumptions and state and nationai trends.
These submodels are grouped into four economic models which forecast future
levels of economic activity and four electricity consumption mode1s which
forecast the associated electricity requirements by consuming sectors. For
two of the consurni ng sectors it was not poss i b 1 e to set up computer rnode l s
and simplifying assumptions were made. The rnodels and assumptions are
described be1ow.
(i) Economic Submodels
The MAP Ec~Mode·l
MAP is an econornetr i c mode 1 based on forecristed or assumed levels
of national economic trends. State government activity, and
develooments in the Alaska resourc~ sector. These economic indl-
cators' are translated into forecasted levels of state•.-~ide popula-
tion by age and sex. employment by industrial sector and ·income.
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The Household Formation Model --·--
The household formation model groups ir.divictua1s 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 ~1odel
This model disaggregates MAP's projections of population and
emplo,').ment into reg·lons of the Railbelt. The model uses econo-
metric techniques to structure regional shares of state popula-
tion and support sector, and government employment.
Housing Stock Model
The housing stock model utilizes the output from the household
formation model, U1e regional populaticn information fr·om the
regional allocation model, and the results of an independent
survey on housing choice. These outputs are combined to produce
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
'or various demand components:
-Residential Non:space Heating Electricit.z Reguirements
This modt::l estimates electricity requirements for household
appliances utilizing the following information:
number of households
appliance saturation rate
fue~ mode split
average annual consumption of appliance
average household size
Residential non-space heating electricity requirements are
obtained by summing the electricity requirements of a11 appli-
ances.
Residential Space Heating
This model 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.
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(b)
Commercial-Industrial-Government
Total electricity requirements for the commerclal-industrial-
government sector is defined as the product of non-agriculturdl
llfage and salary employment and average electric1ty consumption
per· employee. Electricity consumption pt?r employee IS a function
of time and application of conservatlon standards. fh··s 1mpl1es
that new electricity users in this sector will have different
electricity require111ents frmn 1-Jrevious customers.
r1i scell aneous
This model estimates two r·ema1n1ng sectors of elt~ctricity con-
sumption: i.e. str·cet lighting and recreational honu~s.
(iii} Consumption Sectors Not Modeled
Electricity requirements were not modeled for two sectors of demand:
~ilitary
For 1nany reasons. including a lack of histor1cal data, no model
is included to correlate military electricity consumption 11ith
causal factors. Hence, future electricity r·equirements for tt1e
military are asswned to be the san~ as the current level.
Self-Supelied 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. r~ev1 user·s
and future consumption levels are identified from econom~c
scenari as.
As~1mpt ions
To make these mode1s operational, a number of additionc1 assumpt1ons are
incorporated:
The electricity market is presently in relatiye equilibrium except for
space heating in Fairbanks where a shift away from electric space heat-
ing is underway. This equilibrium is expected to remain in effect
throughout the forecast ~eriod because of relatively constant fuel price
ratios.
The price of energy relative to other goods and services will continue
to rise.
Rising real incomes will act to increase the demand for electr·icity.
Federal policies will be effective in the area of appliance ener·gy con-
servation. but will have a rnuch smaller impact on building stock ther:11al
effi r:i enci es.
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(c)
No State conser·vation ~olicies directe(1 exclusively towar<J t:l(~ctriclty
will be implemented.
No significant State polici~s designed to alter the price or availabil-
ity of alternative fuels are implern1~nted.
No new electricity technologies will be introduced.
In terms of residential applia"ces:
saturation rates will follow national trends;
for some appliances. reduced household size wi 11 act to reduce
average ele.::tricity requirements;
consumption is a function of the appliance scrapping rate dS the
average age effects efficiency;
unspecified appliance consumption will increase to acc~mnudate the
possibilHy of new domestic electr·icity app1ications.
In terms of residential space heating:
a slight trend tm'lard single falfllly homes is projected;
average housing unit size will continue to grow;
natural gas availability 1vill not significantly increase;
space heating alternatives such as oil, wood or coal wi 11 not greatly
affect aggregate space heating demanct;
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 uti ·1 ity sales.
For·ecasting Uncertainty
To adequately address the uncertainty associatej with the prediction of
future demands, a number of different economic growth scenarios are consid-
ere:d. These are constructed by alternatively combining high, moderate and
1 ow growth rates in the area of spec i a 1 projects and industry ~-Ji th State
government fiscal policies aimed at stimulating either high, moderate or
low growth. This results in a total of nine potential growth scenarios for
the State. In addition to these scenarios. ISER also considered the poten-
tial impact of a price reduced shift towards increased electricity d~nand.
As outlined below, a short list of six future scenarios were selected.
These concentrated around the mid-range or "most likely" estimate and the
upper and lower extremes.
5-5
(d) Forecast Results --
{ i) 8ase Case
The ISER forecast which incorporates the combination of moderate
economic growth and moderctte government expenditure is considered to
be the "most l;kely" load forecast. This has been identified for
the purpose of this study as the "Base Case Forecast". The resu1ts
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 annua 1 growth rate
of 4.09 percent. Over the period of the forecast, the 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 ISE~ results incorporate a higher
and lower rat~ of economic growth coupled with moder·ate government
expenditure. and also the case where a shift to electricity takes
place. These forecasts do not provide a complete envelope of poten-
tial growth scenarios because the impacts of high industrial growth/
high government expenditure and low ir :ustrial 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 Rail-
belt 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 1 ower and uppt~r 1 imi ts of 2. 8 percent and
6.1 percent r~spectively. rn comparison, historical electricity de-
mand in the Railbelt has increased by 11 percent.
5.4 -Past Projections of Railbelt Electri_<:_it,l' Dem'lnd
A number· of electricity projections have been developed in the past. The dis-
cussion here is confined to work conducted since 1975. The purpose is to com-
pare ISER's forecasts with prev;ous work and to rationalize any differences that
occur.
Forecasts of electric power requirements developed since 1975 (excluding ISER'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 performanc~ Jf these forecasts can be ascertained by
comparing them to 1980 utility sales. Table 5.8 shows the percent error in the
forecasted growth rate to 1980. As can be seen, all of the forecasts signifi-
cantly overestimated 1980 consumption.
These for-ecasts are also shown to be significantly different from those devel-
oped recently by ISER. The differences are mainly attributed to assumptions
concerning economic growth and electricity consumptton rates. Although the eco-
nomic growth assumptions incorporated in previous studies have varied widely,
they have been generally more optimistic with respect to the type, size and tim-
Ing of projects and other economic events. This has consequently resulted in
higher projections of economic activity compared to the recent ISER study.
5-6
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Electricity consumption rates in the ISER studies are generally lower than those
in previous studies. This is essentially because ISER has been the first to
incorporate estimates of appliance saturation rates, end-use patterns and con-
servation measures.
5.5 -Demand Forecasts
(a) ApproacJ!
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 Ener:zy Regulatory Commission was
utilized to determine these load patterns.
(b) Load Patterns
The analysis of load patterns emphasized the identification of average rat-
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
weather conditions .Jnd outages. In any event, it vJas not possible to
detect any patterns in the available data.
The average hourly distribution of generation for the first weeks of A.pril,
August and December were 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 data base resulting in an
overestimation of the load factor. In addition, hourly data also tends to
average out actua 1 peak demands occurring within a time i nterva 1 of 1 ess
than one hour. This could also lead to overestimation of the load factor.
It ·is, however, believed that the accuracy achieved is adequate for these
studies, particularly in light of the relatively flllJCh 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 were allocated
to the individual utilities utilizing a predicted rnix of consumer cate-
gories in the area and the current mix of sales 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
Ra i1 be 1t area •
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The first step involved an adjtJstment to the a1located 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 added together to obtain the
total Railbelt system load pattern for each forecast year. Table 5.9
summarizes the tot a 1 energy generation and the peak 1 oad s for each of the
low, medium, and high ISER sales forecasts, assuminq moderate aovernment
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 Conservatio~
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" 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 tota1 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 manaqement 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 Ught and Power, has insti-
tuted an experimental time-of-day rate for electricity.
Although conservation is essentially iccomplished by a reduction in demand, it
may also be regarded as a means of diverting available energy to other uses, or
creating a "new" source of energy. A recent study by the .IU aska Center for
Policy Studies ( ) indicated that conservation was the most economically attrac-
tive source of new energy available to the Railbe1t area. This conclusion was
based on evidence from existing weatherization programs and projections from the
Alaska Federation for Community Self Reliance in Fairbanks. It should be borne
in mind that the total amounts of energy that can be made available by such
means is relatively small compared to the total Railbelt system energy demand up
to the y1ear 2010.
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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 programs of intensified conservation and load
managemE~nt measures are considered in the generation r:>lanning studies. These
are discussed in more detai 1 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 Rai 1-
belt system electricity forecasts to be used in the generation planning studies
described in Section 8.
(a) ~djusted ISER Forecasts
Three ISER energy forecasts were considered in generation planning studies
(see Table 5.6). These include the base case (MES-GM) or medium forecast,
a 'low and a !!i..9!:!. forecast. The low forecast is that corresponding to the
lo~ileconomic growth as proposed by ISER with an adjustment for low
government expenditure (LES-GL). The high forecast corresponds to the ISER
hi9h economic growth scenario with an adjustment for high government
expenditure (HES-GH).
The electricity forecasts summarized in Table 5.9 represent total utility
generation and include projections for self-supplied industrial and
military generation sectors. Included in these forecasts are transmission
and distribution losses in the range of between 9 and 13 percent depending
upon the generation scenario assumed. These forecasts, ranging from 2. 71
to 4.76 percent average annual growth, were adjusted for use in generation
planning studies.
The self-supplied industrial energy primarily involves drilling and
offshore operations and other activities which are not likely to be
connected into the Rai lbelt 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 provided it remains economic. However, much of their generating c~pa
city is tied to district heating systems which would presumably continue
operation. For study purposes, it was therefore assumed that 30 percent of
the estimated military generation would be supplied from the grid system.
The adjustments made to power and er;ergy 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 used in the
generation planning studies. Annual growth rates range from 1.99 to 5.96
percent for very low and high forecasts with a medium generation forecast
of 3.96 percent.
(b) Forecast Incorporating Load Management
and Conservation
In order to evaluate gener·ation plans under extremely low projected energy
growth rates, the low forecast was further adjusted downward to account for
additional load management and energy conservation. The results of this
scenario also appear on Table 5.10.
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-JSER Conservation Assumptions
For the residential sector, ISER assumed the federally mandated efficien-
cy standards for electrical home appliances would be enforced during 19~1
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 G:ennallen-Valdez
area. Enforcement of mandatory construction or performance standards for
new housing was assumed in 1981 with a reduction of 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.
-Jmpacts 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, 1~78
requires state pub1ic utility commissions to consider certain rate-making
standards for utilities if they have sales in excess of SUO million ki1o-
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 Policv Studies ( ), 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:
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Energy programs provided for in the recent state energy conservation
legislation
Load management concepts now tested by uti 1 ities, inc1uding rate reform
to reflect incremental cost of service and load controls.
These measures could decrease the growth rate of energy and wi r.ter peak
projected in the ISER forecast and the forecasts used 1n generation plan-
ning. The impacts would be mainly in the r~sidentia1 sector.
The impact of state energy conservation legislation has been evaluated in a
study by Energy Probe ( ) and indications are it could reduce the amount of
electricity needed for space heating by 47 percent. ThP total growth rate
in electricity dernand over the 1980-2010 period would drop frorn an average
of 3.98 percent per annum (projected by ISER in the t1ES-GI1 forecast) to
3.49 percent per annum. Energy Probe indicated that ~he electrical energy
growth rate could be reduced even further to 2.70 percent per annum with a
conservation program more stringent than that presently con temp 1 a ted 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 lilflit for electrical demand for purposes of this study. This
represents a 23 percent reduction in grmvth rate which is similar to the
reduction developed in the Energy Probe study.
The implementation of load management measures vwuld 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 1 ow forecast case. l{i th 1 oad 111anagement
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.
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TABLE 5.1 -HISTORICAL ANNUAL GROWTH RATES OF ELECTRIC UTILi ry SALES ,...
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I Anchorage ~o Fairbanks
Period u.s. Areas
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1940 -1950 8.8'10 20.5%
1950 -1960 8.7% ~5.3\':
l I 1960 -1970 7.3?0 1:::.9%
1970 -1978 4.6% 11.7%
I 1970 -1973 6.7% 13.1%
1973 -1978 3. s~.; 10. 9~.;
I 1940 -1978 7.3% 15.2%
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J _j ~-~ _:___] __ _] __ __:__] · __ ] -~_:___] ~-] ~~~=-1 ~= -~=l l -.. ----------·--.. ----
TABLE 5.3-UllllfY SALlS BY RAILB£U REGIONS
i:lreate l' Ancfior age Greater rauEi ... lkS Ciennaiien-Valdez Railbelt Total
1 1 1 1
Sales No. of Sales No. of Sales No. of Sales No. of
Regional Customers Regional Customers Reg10nal Customers Custo100rs
Yeal' GWh Share (Thousands) GWh Share (lhousands) GWh Share (fhousands) GWh (l housands)
1965 J69 78% 31 .u 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 42.8 170 11.6 NA NA 758 54.4
1970 684 75% 46.9 211 24% 12.6 9 1% .8 907 60.J
1971 797 49.5 251 0.1 10 .9 1059 6J.5
1972 906 54.1 262 13.5 6 .4 1174 66.0
1973 1010 %.1 290 1 J.9 11 1.0 1311 71.0
1974 1086 61.8 }22 15.5 14 1.3 1422 78.6
1975 1270 75% 66.1 413 24% 16.2 24 1% 1.9 1707 B4.2
01 1976 1463 71.2 423 17.9 33 2.2 1920 91.3 I ........ 1977 1603 81 .1 447 20.0 42 2.1 2092 103.2 .p.. 1978 1747 79% 87.2 4J2 19% 20.4 38 2% 2.0 2217 109.6
Annual
Growth 12.7% 8.2% 12.1% 6.1% 1}.9% 9.7% 12.6% 7.8%
NOfl:l:
(1) Includes residential and commercial users only, but nut miscellaneous users.
Source: federal l:.nergy Regulatory Commission, Power System Statement (_).
NA: Not 1\vai lable.
_-___] ___ J _J ___ ] --l
TABLE 5.2 -ANNUAL GROWTH RATES ,~UTILITY CUSTOMERS AND CONSUMPTION PER CUSTOMER
Greater Anchorage Greater fairbanks u.s.
Customers Consumption per Customers Consumption per Customers Consumpt ion 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
U1
I
1-' 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
] E l ~::____] ___ ] ~ _::_:_] :_ _ _j '_________] =_J _____] _ ___3 __ ] _:==~1 ___:=:~ .. -... ~.,. -~. -------~-------
TABL[ 5.3 -Ul1L1TY SAL£5 BY RAILB£LT REGIONS
Greater Anchorage Greater rair6anks Giennaiien-Vaiaez Ra1lbelt Total
1 1 1 1
Sales No. of Sales No. of Sales No. of Sales No. of
Regional Customers '"R'egional Customers Reg10nal Customers Customers
Year GWh Share (Thousands) GWh Share (lhousands) GWh Share (Thousands) GWh (Thousands)
196S 369 78% 31.0 98 21% 9.5 6 1% .6 4 73 41.1
"1966 415 32.2 108 9.6 NA NA 52} 41.13
1967 461 34.4 6.S NA NA NJ\ 527 34.4
1968 519 J9.2 141 10.8 NA NA 661 3U.O
1969 587 42.8 170 11.6 NJ\ NA n8 54.4
1970 684 75% 46.9 213 24% 12.6 9 1% .8 907 60.>
1971 797 49.5 251 13.1 10 ,9 "i!J~9 63. s
1972 906 54.1 262 1J,5 6 .4 1174 68.0
1973 1010 S6.1 290 13.9 11 1.0 1311 71.0
1974 1086 61.8 }22 15.5 14 1.3 1422 7~.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 I
~ 1977 1603 81.1 447 20.0 42 2.1 l092 103.2 ~ '.978 1747 79% iH .2 432 19% 20.4 38 2% 2.0 2217 109.6
Annual
Growth 12.7% 8.2% 12.1% 6,1% U,9% 9.7% 12.6% 7.8%
NOTES:
(1) 1ncludes 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 E.ND-U':E CONSUMPTION ( GWh)
Commercial-Industrial
Year Residential -Government Miscellaneous
1965 214 248 9
1966 241 275 8
1967 20i, 241 8
1968 294 355 11
1969 339 407 12
1970 402 489 14
""'! 1971 478 555 25
I 1972 542 613 1 7
I 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% B.B%
l
I % of Annual
Consumption
l 1965 45% 53% 2%
1970 44% 54% 2%
1975 46% 52% 2%
1978 47% 52% 1%
.....,
I
....
5-15
____] --·] ____] ___ J =-~-_] ---=-1 - -I _-_~__) :_:::_____:J =-----l ___J ~ ---1 ---i ------!
...... -----· "• ~'"' ------·--T--.···-···· . -- ---------.. --
TABLE 5. 5 -BASE CASE fORECASl (MES-GM) 1 (GWh)
OEilif~ Sales Eo ~II Consum1nl Sectors Sales Mli 1tary Self-Supplied
G ennallen-Net Industry Net
Year Anchorage fairbanks Valdez Total Utilit~ Generation Generation
1980 1907 446 37 2390 334 414
1985 2l!38 669 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 0.0 3.27
U1 1990-2000 4.81 4.12 3.12 4.76 o.o o.o
l 2000-2010 3.27 3.57 3.22 3.33 0.0 0.0 ........ 1980-2010 3.85 4.50 4.54 4.09 o.o 1.08 0'1
NOIES:
(1) Reproduced from ISER's ( -) Medium Economic Growth/Moderate Government Expenditure Scenario
(without price induced shift to elect ric it y).
U1
I ...... .......,
TABLE 5.6-SUMMARY OF RAilBELT ELECTRICITY PROJECTIONS
Utilit~ Sales to All Consuming Sectors
lES-GL 1 HES-GM
Year Bound LES-GM (Base Case)
1980 2390 2390 2390
1985 2798 2921 3l71
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
1960-2010 2.78 3.22 4.09
NJTES:
Lower Bound ; Estimates for LES-GL
Upper Bound ; Estimates for HES-GH
lES ; Low Economic Gro~th
MES = Medium Economic Growth
liES = High Economic Growth
Gl = low Government Expenditure
GM = Moderate Government Expenditure
GH = High Government Expenditure
t.£S-GM
with Price
Induced Shift HES-GM
2390 2390
3171 3561
3599 4282
4617 5789
6525 7192
8219 9177
10142 11736
4.16 6.00
6.13 5.32
4. 51 5.02
4.94 5.45
(1) Results generated by Acres, all others by ISER (_).
Military Net
(GWh) Generation (GWh)
HES-GH 1 t.£5-GH
Bound (Base Case) lES-GM
2390 334 414
3707 334 414
4443 334 414
6317 334 414
8010 334 414
10596 334 414
14009 334 414
6.40 0.0 0.0
6.07 0.0 0.0
5. 75 0.0 o.o
6.07 o.o 0.0
=----=:1 ----1 -1 -----1
Self-Supplied
Industry Net :::enerat ion (GWh)
t-£5-GH
MES-GM with Price
(Base Case) I nduced Shift HES-GH
414 414 414
571 571 847
571 571 981
571 571 981
571 571 981
571 571 981
571 571 981
3.27 3.27 9.0
0.0 0.0 0.0
0.0 0.0 o.o
1.06 1.08 2.92
-
U1
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CX)
l 1 J ___ ) -
-J _ __] =---_J _________j _____] ___ ] --~--~ ~~ ___ ) _:__:__j ___ ] ----l --=--~ ---1
-------------- -----
TABLE 5.7 -SUMMARY OF RECENT PROJECTIONS Of RAILBELT ELECTRIC POWER REQUIREMENTS (GWh)
Study NumberiSource
1. South Central Railbelt Area 2 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
198ci
low Med High
3020 3240 3550
Institute of Social and Economic 2478 -38"17
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 Memorand'-!m:
Electric Power Needs Assessment,
South Central Alaska Water
Resources Committee, i979 ( )
2600 -3400
2920 3155 3410
1990 1995 2000 2025
Low Med H igh __ ..;;.L_o'"'-w__;.M.;.;e,.;;d__;H.;.;i"'"g"'h __ ...;:L..:;.o..:w---'M.;.;;e..:d'-H;.;,.;;c.;ig"'"h'--_ __;;;L..;;.o_w_H..:e-'-d_H'-1"'-'. g"'"h'-
5470 6480 8540 6656 8688 12576 8100 11650 18520
5415 12706 8092 -20984
8500 -10800 10341 17552 16000 -22500
.4550 6110 8200 5672 8175 11778 7070 10940 16920 8110 17770 38020
-----·~ ..
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Study
Number
2
3
4
NOTES:
Year of
TABLE ~.8 -PERfORMANCE Of PAST PROJECTIONS
RAILBELT ELECTRIC POWER REOUI~EMENTS 1
Annual Growth Rate of Percent Error4
Net Energy Between in forecaot
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
0~) Cor.responds to Tabla 5.7. Cn Assuming 1980 Net Energy consisting of 2390 of sales plus 10 percent losses.
(~>) Indicates overestimation.
5-19
=---:___] =----1 __ _] __ ---_] ~-~] _ __] ~ ~~ =-------~ : --] :_______:::] :____:____] _____:__:] -----~ =--:_____::] ==-=~ ---lil8l ------.. ------.. -
TABU~ 5.9 -fORECAST TOIAl G£Nl:.RATlON AND Pl:.AK lOADS -TOTAl RAllBllT Rl:.GION 1
ISER low (l£S-GH)2 IS£R Medium (M£5-GH) 15£R High (H£5-GM)
Peak Peak Peak
Generation load Generation load Generatim1 load
Year (GWh) (MW) (GWh) (HW) (GWh) (HW)
1978 JJZ3 606 .HZJ 606 3323 606
1980 3522 643 3522 643 4135 753
1985 4141 7S7 4429 BOB 5528 995
1990 4503 824 4922 898 6336 1146
1995 5.H1 977 6050 1105 8013 1456
2000 6599 1210 7327 1341 9598 1750
2005 7188 1319 8471 ns1 11843 2158
2010 7822 1435 9838 1800 14730 268J
Ul
I
N
0 Percent. 2. 71 2. 7J 3.45 },46 4.76 4.76
Growth/Yr.
1978-2010
(1) Includes net generation fHlffi military and self-supplied industry s::.urLes.
Source: Reference ( )
(2) All forecasts assume moderate government expenditun~.
"""
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TABLE. 5.10 -RA1LB£LT REGION LOAD AND E.NE.RGY FORECASTS
USED FOR GENERA! ION PLANNING STUDIES
---
l D A D C A 5 E
Low Plus Load
Management and low Medium High
Conservation
(LES-GL)2 (ME.S-GM)3 (HE.S-GH)4 (LES-GL Ad,justed) 1
Load toaa Coaa • • load
..Y.!.!L.. ..1:i'!. GWh factor MW GWh factor MW GWh Factor MW GWh Factor
'1980 5Hl 2190 62.5 510 2790 62.4 510 2790 62.4 ';10 2790 62.4
1985 56[] 3090 62.8 580 3160 62.4 6.J0 3570 62.6 69~ 3860 6}.4
1990 620 3430 63.2 640 35()~ 62.4 735 4030 62.6 920 5090 63.1
1995 68~) 3810 63.5 795 4350 62.3 945 5170 62.5 1295 7120 62.8
2000 75:> 4240 63.8 950 ~210 62.3 1175 6430 62.4 1670 9170 62.6
zoos 835 4690 64.1 1045 5700 62.2 1380 7530 62.3 2285 12540 62.6
2010 no 5200 64.4 1:40 6220 62.2 1635 8940 62.4 2900 15930 62.7
( 1) LE.S-GL:
(2) l£5-GL:
(3) MES-GM:
(4) HES-GH:
Low economic growth/low government expenditure with load management and conservation.
Low economic growth/low government expenditure.
Medium economic growth/moderate government expenditure.
High economic growth/high gove~nment expenditure.
5-21
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:woo
1~)00
1()00
0 ~----------~------------~-------------J 1965 1970 1975 1980
YEAR
HISTORICAL TOTAL RAILBELT UTILITY SALES
TO FJNAL CUSTOMERS
FIGURf. 5.1 llliJ
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. ~, ....
, I
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"""'.j,,
, I t.
-
-
18~----------------------------------------------------------~
17
16
LEGEND
HES-GH : HIGH ECONOMIC GROWTH + HIGH GOVERNMENT EXPENDITURE
HES-GM : HIGH ECONOMIC GROWTH + MODERATE GOVERNMENT EXPENDITURE
MES -GM ~ MODERATE ECONOMIC GROWTH + ~RATE GOVERNMENT EXPENDITURE
LES ·GM : WW ECONOMIC GROWTH t MODERATE GOVERNMENT EXPENDITURE
LES-GL : LOW ECONCMIC GRONTH +LOW GOVERNMENT EXPENDITURE
15~------------------~------------------~------·------------~
14
13
12
I
/
/
HES-GH I
/
/
~
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~ 10~------------------+--------------------r------~------~--~
...J
<t
(J)
> 1-
9
~ 8
0:
1-
~ 7
..J
L&J
6
5
4
2
o~------------._----------~--------~--------~--------_. __________ ~ 1980 1985 1990 1995 2000 2005 2010
YEAR
FORECAST ALTERNATIVE TOTAL RAILBELT
UTILITY SALES
FIGURE 5.2
~;
li
IIU
P------------,----------~--------------------------------------·----------------~
16
15
14
13
12
II
-:I:
tiES· GH : HIGH ECONOMIC GROWTH 1' HIGH GOVERNMENT EXPENDITURE
MES • GM : MODERATE ECONOMIC GROWTH 1' MODERATE GOVERNMENT EXPENDITURE
I_ES -GL : LOW ECONOMIC GROWTH t LOW GOVERNMENT EXPENDITURE
LE~) • GL AO.JUSTED = LOW ECONOMIC GROWTH +LOW GOVERNMENT
EXPENDITURE 1' LOAD MANAGEMENT AND CONSERVATION
I
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(!) -z
0
~ a: w z w
(!)
>-t-
C3
iE
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9
8
7
6
,
5
4
3
2
,
/
/
~ , , /
/ ,
/
, ,
~ ,
, ,
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_.,..,. --------LES-GL
ADJUSTED
0~--------~--------_.--------~~~--------._--------~,--------~ 1980 1985 1990 1995 2000 2005 2010
YEAR
ENERGY FORECASTS USED FOR GENERATION PLANNING STUDIES
FIGURE 5.3
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6 -RAILBELT SYSTEM AND FUTURE POWER GENERATION OPTIONS
6.1 -Introduction
Effective planning of future electric power generation sources to meet the pro-
jected n1~eds 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
requir·ed in satisfying those needs within the constraints of technical feasi-
bility, ~~conornic 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 Railbelt 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 detennine the most economic basin deve'lopment plan which clearly
defines details such as dam heights, installed generating capacities, reservoir
operat i n9 y·ul es, 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 Railbelt system
containing several different types of generating sources. These sources inc 1 ude
both thermal and hydropower generating facilities capable of satisfying a speci-
fied load forecast. Economic analyses of scenarios containing alternative
Susitna Basin development plans being investigated would then reveal which is
the most economic basin development plan. This process and the comparison of
other factors such as environmental impacts and social preferences, essentially
falls within the purview of "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 at 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 as 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 Northwest 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 cost
data for inclusion in the alternative Railbelt system generation scenarios. The
primary object·ive is to carry out a preliminary assessment of the feasibility of
the sele1:ted Susitna Basin development plan by comparing the costs and benefits
of the 11 1rlith Susitna scenario" with selected "without Susitna scenarios".
6-1
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6.2-Existing System Characteristics
(a) S,yst1em Description
The two major load centers of the Rai lbelt 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 tr·ansmission
system between Anchorage and Willow consists of a network of 115 kV and 138
kV lines with interconnection to Palmer. Fairbanks is orimarily 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
con s.u 1t ed :
(i) Published Documents
-WCC Report, "Forecasting Peak Electrical Demand for
Alaska's Rai lbelt", September, 1980 (_}.
-IECO Transmission Report for the Railbelt, 1978 ( ___ ).
-U.S. DOE, "Inventory of Power Plants in the U.S.," April
1979 (_).
-Electrical World Directory of Public Utili~ies 1979-1980
Edition (_).
-Williams Brothers Engineering Company, 1978 Report on FMUS
and GVEA Systems.
-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
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planning st~dies described in this report and represents a resolution of
discrepancies in data collected.
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 Table 6.3.
(b) Schedule Retirements
In order to establish a retirement policy for the existing generating
units, several references were consulted including the APA draft feasi-
b. lity study guidelines ( ), FERC guidelines ( ), and historical
records. Utilities, partiCUlarly those in the Fa1rbanks arc~, were also
consulted. Based on the above, the following retirement periods of opera-
tion were adopted for use in this study:
-Large Coal-Fired Steam Turbines(> 100 MW):
-Small Coal-Fired Steam Turbines(< 100 MW):
-Oi 1-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 plant 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
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-line.
6-3
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A brief study was undertaken to check the va 1 i dity 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
11 intertij~ scenario 11
, allows for additional transmission to be added as needed,
with i nc1"'eased capacity r·equi rements 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 1ines from Anchorage to ~illow and from Healy to Fairbanks in
1986. No additior1al 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 ~resent worth cost in 1980 dollars of
the second scenario exceeds that of the first by just over $300 million.
The anallysis 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 yea~~ 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 generatior.
scenarios, the cost of such intertie facilities were also assumed to be common.
However, in final compari.sons of a lesser number of preferred alternative
scenarios, appropriat~ 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 -~~droelectric 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 pote~ntial 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
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generation scenarios with and without the project. An obvious "without Susitna"
scenario is one which includes hydroelectric developments outside the Sustina
Basin. The plan formulation and selection methodo1ogy discussed in Section 1.4
and Appendix A has been app1ied in the development 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
hydroele~ctric developments other than Susitna are discussed in this Section.
(a) Assessment of Hydro Alternative_?
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 estab 1 i shed the over a 11
objective of the exercise as the selection of an optimum Railbelt genera-
tion plan which incorporated the proposed non-Susitna hydroelectric
developments, 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 Hydropo'rler Study ( ) and the 1\PA
report "Hydroelectric Alternatives for the Alaska Railbelt"( ).
{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 formulation, essentially on the basis of
pub 1 i shed data on the sites and appropriately defined criteria. The fit-st
iteration in this process was based on a coarse screen in which sites which
wer~e considered tect·nically infeasible or not economically viable were
rejected~ For this purpose, economic viability for a site was defined as
en1~rgy production costs less than 50 mills per kWh, based on economic para-
meters. This value was considered to be a reasonable upper limit consis-
tent with Susitna Basin a1t.er·natives (See Section 2) •
En1~rgy 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 Here 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.
Fm· 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 rejected and the remaining 65
sites were subjected to a second iteration of screening. The additional
criteria established for this screening w2re environmental in nature.
Based on data published in the COE and APAd reports, References ( ) and
( ), rejection of sites occurred if:
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(i) They would cause significant impacts within the boundaries of an
exist1ng Nation.al Park or a proclaimed National ~lonument area;
(ii) They were located on a river in which:
-anadromous fish are known to exist;
-the annu1l passage of fish at the site exceeds 50,000;
- a confluence with a tributary occur-'), upstream of the site, in wriich
a major spawning or fishing area s 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
screi~ning. At this stage in the selection 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 deriveo by judgemental
elimination of the more obviously uneconomic or less environmental-ly accep-
table sites. These sites were then categorized into sizes as follm·1S:
-less than 25 MW: 5 sites
-25 MW to 100 MW: 15 sites
-greater than 100 MW: 8 sites
The fourth and final screen was then performed in which a more detailed
numerical environmental assessment was made. Eight evaluation criteria
were •Jt i1 i zed:
-Impact on big game
-Impact on agricultural potential
Impact on waterfowl, raptors and endangered species
-Impact on anadromous fish
-Restricted land uses
-Impact on wilderness areas
-Impact on cultural, recreational and scientific resources
-Impact generated by access
The above environmental ranking criteria \vere assigned numerical weights,
and scale ratings for each site and each criterion were developed using
ava-ilable 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
1 i s ted i n Tab 1 e 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 g~~era
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 allowance for contin-
gencies and 10 percent for engineering and owner 1 S administration. A total
of five plans were formulated incorporating various combinations of these
sites as input to the Step 5 evaluations.
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Power and energy values for each of the developments werre re-evaluated in
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. The 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 e~conomi c parameters estab 1 i shed 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
anallyses (See Section 6.5), in groups of two or three. The most economic
schemes were introduced first and were followed by the less economic
schE!mes.
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 projects (See also Figure
6.4). .
Add'itional sites such as Strandline, Allison Creek and Ta.lkeetna.·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 portion 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 o~ 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, coal
and oil-fired generation sources only, from the standpoint of technical and
economic feasibility alone. The broader perspectives of other alternative
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resources and the relevant environmental, social a11d 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
-Ga1s-fired combined-cycle
-Gas-fired gas turbine
-Oiesel
To forw•late 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 1..Jainwright 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 MW. 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 admi ni strati on. The costs ~'4ere deve ·1 oped
using published data for the lower 48 ( ) and appropriate Alaska
scaling factors based on studies conducted by Battelle ( ). 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 { ), the capital
costs incorporate provision for installation of fluegas desulfuriza-
tion for sulphur control, highly efficient combustion technologv for
control of nitrogen acids and baghouses for particulate re~ov21.
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{ii) Fuel Costs
The total estimated coal reserves in Alaska are shown on Table 6.6.
Projected opportunity costs for Alaskan coal range from $1.00 to $1.33
per million Btu. A cost of $1.15 was selected as th~ 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 ir.~icated oppor~
tuni ty cost.
Real growth rates in r.oal costs (excluding general price inflation)
are based on fuel escalation rates developed by the Department of
Energy {DOE) { } in the mid-term Energy Forecasting System for DOE
Region 10 whicn 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 utili-
ties more accurately than equivalent rates pertaining to the commer-
cial and residential sectors. A composite annual escalation rate of
2. 93 percent has been computed for the per·i ad 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 a: suggested by the DOE.
Beyond 2005, zero real growth in the coal price is assumed.
(iii) Other Performance Characteristics
Annual operation and maintenance costs and representative forced out-
age rates arP. shown on Table 6.5.
(c) Combi ned Cyc 1 e
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 is under constr,Jction (See Table 6.1). The plant under construction
is the Be 1 uga #9 unit owned by Chugach Electric Association ( CEA). It wi 11
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 piants 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 { _).
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.
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Fuel Costs
The combined cycle facilities 'r'IOUld burn only yas 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.
Other Performance Characteristics
Annual operation and maintenance costs and a representative forced
outage rate are given in Table 6.5.
Gas-Turbine
Gas turbines are by far the main source of thermal pO'r'ler 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, siulplicity 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
( i i )
A unit size of 75 MW was considered to be representative of a modern
gas turbine plant addit·ion in the Railbelt region. However, the
possibility of installing gas turbine units at Beluga was not con-
sidered, since the Beluga development is at this time prim.--·ily 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 owner's administration.
This cost includes provision for wet control of ~ir emissions.
Fuel Costs
Gas turbine units can be operated on oi 1 as He11 as natural gas. The
opportunity value and market cost for oi1 are considered to be equal,
at $4.00 per million Btu. Real annual growth rates in oil costs were
developed as described above and amounted to 3.58 percent for the
1980-2005 period and zero percent thereafter.
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(iii) Other Performance Characteristics
Annual operation and maintenance costs and forced outage tates 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
retired in the past several years due to high fuel prices. About 65 iVlW 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 L:se 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
in Table 6.5.
(f) Plan Formulation and Evaluation
The six candi~ate 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 were considered in
formulating plans. The first, called the "renewal" policy allowed 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 11 policy assumed that the , ~ilities
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 1~00
hours of annual operation (see Condition 9 of the FUA as discussed in
Section 6.6).
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In the su~sequent Step 5 evaluation of the two basic plans, the OGP5 gener-
ation planning model was utilized to develop a 1east cost scenario incor-
porating the n1ecessary coal~ oil, and gas fired generating units. The
results for the very low, low, medium, and high load forecasts are sun~ar
ized in Table 6.4. They indicate thdt for the medium forecast the total
system present worth cost is s 1 i ght 1 y higher than $8,100 mi 11 ion.
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, it is assumed that the 11 M renewalsu 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 graphically.
6.6 -Impact of the Fuel Use Act
(a) Background
The 11 Power Plant and Industrial Fuel Use Act of 1978 11 (FUA), Public Law
95-620, 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 p1ant and precludes the
construction of any new power plant without the capability to u~e 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) Cogeneration
(2) Fuel mixture
(3) Emergency purposes
(4) Maintenance of reliability of service (short development lead time)
(5) Inability to obtain adequate capital
(6) State or local requirements
(7) Inability to comply with applicable environmental requirements
(8) Site limitations
(9) Peak load power plants
(10) Intermediate load power plants
(11) Lack of alternative fuel supply for the first ten years of useful
life
{12) Lack of alternative fuel supply at a cost which does not substan-
tially exceed the cost of using imported petroleum.
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(b) FUA and the Railbelt
The two Anchorage utilities, Chugach Electric Ass~ciation (CEA) and Anchor-
age Municipal Light and Power Department (AMLPD) have been able to maintain
relatively low electric rates tu their customers by the ~se of natural gas
from the Cook Inlet region. As reported to the DOE in June of 1980, CEA
pa~d an average of $0.32/Million Btu (MMBtu) for gas, with its cheapest
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
favorable 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 uoppor-
tuniti' cost of $2.00/MMBtu discussed earlier is considered appropriate for
future system comparisons and relevent to the discussion on the FUA
presented 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 low 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 whic~ would preclude the development of the plant using
an alternative fuel. As no such constraint is foreseen, it is likely that
these categories would apply.
To obtain an exemption under category 8, it must be shown that alternative
fuels are inaccess\ble due to physical limitations, and that transporta-
tion, handling and storage, and waste disposal facilities are unavailable
or other physical limitations 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
that 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 which would exceed a national air quality standard. However, due
to the shift in concern regarding the use of gas as compared to oi 1, this
requirement 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.
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(c)
Exemption 10 for intcr~ediate load power plants is available only when
petroleum is used as the primary energy source. This exemption category
would 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 1ow. 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 decis1on. 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.
Conclusions
The Anchorage utilities are subject to the prohibitions of the FUA for the
development of new 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,
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 wou1d 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 ( ). Of
these, all but one are low temperature sources (100-200°F) and therefore
reasible only for building or process heating. The high temperature
Klawasi site, located east of Glennallen, has been recently investigated
for electric power generation potential { ). Although a study has been
made for the development of this site, it-has not been funded. No pot~n
tial 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 west. 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.
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Based upon available data, a potential site capacity on the order of
several hundred MW may exist, although only a 25 M~J 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 in the v1orld, with mean tides ranges of more than 30 feet at
Sunrise, an Turnagain Arm, 26 feet at Anchorage, and decreasing towards the
lower reaches of Cook Inlet to 15 feet or so near Seldovia. Several
initial studies of Cook Inlet tidal power development ( , ) have con-
cluded that generation from tide fluctuation is technicallyfeasible and
numerous conceptual schemes ranging in estimated capacity of 50 ~'!W 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 C'.lrrently underway to develop more specific information on how
much and whic!1 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.
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Table 6.1 -TOTAL GENERATING CAPACITY WITHIN THE RAILBELT SYSTEM
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Rui5eiE [Jhhtl! InstaTiea ~aeaciEt (~~} -wc~c ' lt~d( ) DOt! } ttt:.wo.( -) ACRES
Abbreviations Name 1980-1978-1979-1979 1980
AMLPD Anchorage Municipal Light & Power
i
Department 184.0 130.5 148.0 108.9 215.4
CEA Chugach Electric Association 420.0 411.0 402.2 410.9 411.0
GVEA Golden Valley Electric Association 211.0 218.6 230.0 211.0 211.0
FMUS fairbanks Municipal Utility System 67.0 65.5 68.2 67.4 67.2
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CVEA Copper Valley Electric Association 18.0 13.0
MEA Matanuska Electric Association 0.9 0.6 3.0 0.9 0.9
HEA Homer Electric Association 2.6 9.2 1.7 3.5 2.6
SES Seward Electric System 5.5 5.5 5,5 5.5 5.5
APAd Alaska Power Administration 30.0 30.0 JD.O 30.0 -• TOTAL 909.0 970,9 901.6 838.0 943.6
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Table 6.2 -GENERATING UNITS WITHIN THE RAILBELT -1980
lrail6elt station Unit unit Installat 10n Heat Rate !nstalled Mimmum Maximum Fuel Retirement
Utility Name II Type Year (STU/kWH) Capacity Capacity Capacity Type Year
(MW) (MW) (MW)
Anchorage AJ.l.PD 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 AMLPO 4 GT 1972 12,000 2&.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 1 5.1 NA NA NG 1998
Assoc iat ion Beluga 3 GJ 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 GJ 1976 13,742 67 .B NA NA NG 2006
Beluga 7 GT 1978 n, 742 67 .a 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
a-. Internet ional 39,973~ I Stat ion 1 GT 1':165 14.5 NA NA NG 1995 ...... 2 GT 1975 39,9731 14.5 NA NA NG 1995 " 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 ;;:ooz
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 6<>.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 3 Oil 2000
_,
-~ -· -.....
Table 6.2 (Continued)
Ra1lbelt stat 10n Umt Unit lnstallahon Heat Rate Installed Mtmmun Maximun Fuel Ret1rement
Utility Name II Type Year (BTU/kWH) Capacity Capacity Capacity Type Year
(MW) (MW) (MW)
Fairbanks Chen a 1 ST 1954 14,000 5.0 2 5 Coal 1989
Municipal 2 sr 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 sr 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 J Oil 1997
2 IC 1968 11,000 2.7 1 } Oil 1998
3 IC 1968 11,000 2.7 1 3 Oil 1998
Horner Elec. Homer=
Associl:ltion Kenai IC 1979 15,000 0.9 NA NA Oil 2009
(HEA) Pt. Grahan I 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 Oii 1994
} IC 1970 15,000 0.6 NA NA Oil 2000 m
I Matanu;>ka Talkeetna IC 1967 15,000 0.9 NA NA Oil 1997 ...... co [lee. Assoc.
(MEA)
Seward SES IC 1965 15,000 1.5 NA NA Oil 1995
Electric
System (SES) z IC 1965 15,000 1.5 NA NA Oil 1995
Alaska Eklutna IW 1955 30.0 NA NA zoos
Power
Administration
(APAd)
TOTAL 943.6
Notes:
GT = Gas turbine
CC = Combined cycle
HY =Conventional hydro
IC = Internal Combustion
Sf = Steam turbine
NG = Natural gas
NA = Not available
( 1) This value judged to be unrealistic for large
to 15,000 for generation planning studies.
range planning and therefore is adjusted
-
Table 6.3 -OPERATING AND ECONOMIC PARAMETERS FOR SELECTED HYDROELECTRIC PLANTS
I""" Max. Average Economic 2
Gross Installed Annual Plant Capit~l Cost of
Head Capacity Eneryy Factor Cos~ Energy
No. Site River Ft. (MW) (Gwh (%) ($10 ) ($/1000 Kwh)
1 Snow Snow 690 50 220 50 204 61
2 Bruskasna Nenana 235 30 140 53 238 113
3 Keetna Talkeetna 330 100 395 45 4633 73
4 Cache Talkeetna 310 50 220 51 4563 136
5 Browne Nenana 195 100 410 47 8883 140
6 Talkeetna-2 Talkeetna 350 50 215 50 387 3 117
7 Hicks Matanuska 275 60 245 46 607 161
B Chakachamna Olakachatna 945 !t';O 1925 46 1200 40 r-9 Allison Allison Creek 1270 8 33 47 54 125
10 Strand line
Lake Beluga 810 20 85 49 126 115
NOTES:
~ncluding engineering and owner's administrative costs but excluding AFDC.
(Z) Including AFDC, Insurance, Amortization, and Ope rat ion and Maintenance Costs.
I'""' (3) These costs are currently being revised. I ,
-
6-19
. J ~~~~
---- -
----·----- -
--
Table 6.4 -RESULTS Of ECONOMIC ANALYSES OF ALTERNATIVE GENERATION SCENARIOS
Installed Capac1ty (MW) by lotal System Jotal System
Categor~ in 2010 Installed Present Worth
Generation Scenario OGP5 Run ifiermai H~•dro Capacity in Cost
____!xee [Lscr lf!E 10n Load forecast ld. No. Coal Gas Oil 2010 (MW) ($106)
All Thermal No Renewals Very Low1 LBT7 500 426 90 144 1160 4930
No Renewals Low L7E1 700 300 40 144 1385 5920
With Renewals low L2C7 600 657 3D 144 1431 5910
No Renewals Mediurn LME1 900 801 50 144 1695 8130
With Renewals Medium LME3 900 807 40 144 1891 8110
1'-lo Renewals High L7f7 2000 1176 50 144 3370 13520
With Renewals High L2E9 2000 576 no 144 3306 13630
No Renewals Probab il ist ic un 1100 1176 100 144 3120 6320
Thermal Plus No Renewals Plus: Medium L7W1 600 576 70 764 2010 7080
Alternative Chakachamna (500)2-1993
Hydro Xeetna (120)-1997
No Renewals Plus: Mediurn Lfl7 700 501 10 814 2025 7040
Chakachamna (500)-1993
Keetna (120)-199i
O'l Snow (50)-2002
I
N No Renewals Plus: Medium LWP7 500 576 60 847 1983 7064
0 Chakachamna (500)-1993
Keetna (120)-1996
Strandline (20),
Allison Creek (B),
Snow (50)-1998
No Renewals Plus: Medium LXF 1 700 426 30 847 2003 7041
Chakachamna (500)-1993
Keetna (120)-1996
Strandline (20),
Allison Creek (8),
Snow (50)-2002
No Renewals Plus: Medium l403 500 576 30 947 2053 7088
Chakachamna (500)-1993
Keetna (120)-1996
Snow (50), Cache (50),
Allison Creek (B),
Talkeetna-2 (50),
Strar.dline (20)-2002
Notes:
(1) Incorporat iilg load management and conservation
(2) Installed capacity
j I • 1 1 ---1
Table 6.5 -SUM~ARY OF THERMAL GENERATING RESOURCE PLANT PARAMETERS
PLANT TYPE
~O~L-riR£0 5T£~M COMBINED GAS
Parameter CYCLE TURBINE DIESEL
500 MW 250 MW 100 MW 250 MW 75 MW 10 MW
Heat Rate (Btu/kWh) 10,500 10,500 10,500 8,500 12,000 11,500
O&H Costs
Fixed O&H ($/yr/kW) 0.50 1.05 1.30 2,75 2.75 0.50
Variable O&H ($/MWH) 1.40 1.80 2.20 o.:m O.JO s.oo
Outages
Planned Outages (%) 11 11 11 14 11 1
Forced Outages (%) 5 5 5 6 3.8 5
Construction Period (yrs) 6 6 5 J 2
0\ Start-up Time (yrs) 6 6 6 4 4
I
N Total Ca~ital Cost ,_.
($ r.nl 10n)
Railbelt; 175 26 7.7
Beluga: 1,130 630 290
Unit Ca~ital Cost ($/kW)1
Railbelt: 728 250 778
Beluga: 2473 2744 3102
Notes:
(1) Including AFDC at 0 percent escalation and 3 percent interest.
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Table 6.6 -ALASKAN FUEL RESERVES
Reserve
Coal (million tons)
Gas (billion cubic feet)
Oil (billion cubic feet)
Field
Buluga
Nenana
Kenai
Matanuska
North Slope
Cook Inlet
North Slope
Cook Inlet
Approximate
Reserve
2400
2000
300
100
29000 plus
4200 plus
8400 plus
zoo
Rea£i~
Value
Btu/lb
7200 -8900
7500 -9400
6500 -8500
10300 -14000
Table 6. 7 -FUEL COSTS AND ESCALATION RATES SELECTED FOR
GENERATION PLANNING STUOIE~-------
Parameter Natural Gas 011
Economic: Cost -$/Million BTu 2.00 1.15 4.00
Annual Escalation Rate -.,
"' P~nod: 1980 -zoos 3.98 2.93 3.58
2006 -2010 0 0 0
6-22
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LOCATION MAP
. ~@..
;:>ROPOSED
DAM SITES
----PROPOSED 138 KV LINE
-EXISTING LINES
0 20 60
SCALE IN MILES
FIGURE
SITE
SELECTION
PREViOUS
STUDIES
ENGENEERING
LAYOUTS AND
COST STUDIES
ECONOMICS
ENVIRONMENTAL
OBJECTIVE
ECONOMICS
4 ITERATIONS
SNOW ( S)
BRUSKASNA ( B )
KEETNA ( K)
CACHE ( CA)
BROWNE ( BR)
TALKEETNA-2 (T-2)
HICKS (H)
CHAKACHAMNA (CH)
ALLISON CREEK ( AC)
STRANDLINE LAKE ( SL}
-CH, K
-CH, K,S
DATA ON DIFFERENT
THERMAL GENERATING
SOURCES
COMPUTER MODELS TO
EVALUATE
-POWER AND
ENERGY YIELDS
-SYSTEM WIDE
ECONOMICS
CRITERIA
ECONOMICS
cH ,K, s a THERMAL
LEGEND
-CH, K,S,SL,AC
-CH,K,S,SL,AC
-CH,K,S,Sl,AC,CA,T-2 ---~ STEP NUMBER
IN STANDARD
PROCESS
{APPENDIX A)
FORMULATION OF PLANS INCORPORATING NON-SUSITNA HYDRO GENERATION
FIGURE 6.2
-
-
-
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~---------------------------------------------------------------------1 154 o ~~z"' !4a-o 146.0 ~44e I .. _.;;.
jl ®i
, " 0 N
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J l. I
KEY PLAN I
--r _j_::..=::,.---t--\
{.
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-~-~-----------·
0 F A L A
1 s K A
RAILBELT REGiON SCALE · ~AI<.. E S
8 [J 0
0-25 ~ Z5-l00 ~~ :.100 H./
L Strandline L. :3. J"inis.~;:eri 26 .. s~o-.. 39. Le:ne
2. Lower Bel u9A .~. Co~l 27. kendi Lo·..-e r 1!.0~ Tn~, c• ... 1 tn!l
3. Lowe~ l·!ke Cr. . -• j. Cnv1 i tna ,.
~!< • Gerstle q, fentna
4. .,
"' 1 is on c~. ;6. Qhlo 29. Tanar;a R. ~{. Ca tJ·H:~rd l B 1 uf fs.
5. Crescent Lal<il z :7. Lower Chulitna .J:.J. B,...ust.a~r.a .: 3. John !ion
6. Grant Lake :a. Cacne -.. (dr. t, s-J'H":C L4. 8-rO"I'tl'~""re
l. &C1 ure ~~y :9. ~reens tone-32. ;QpP,... E.e lu-.;a !S.. Ji.Jr'>( t_ ~ 0'1 H ...
B. Jy.an 22·. -a.:il::eetna 2 }3. :o.r fee ,, 'J~ chon ls. upper r-..e. 11e--o.
9. P<:lwer C!"f!U 2 ~' ~ra.nl t4l Gor~e .,:0'"'~. G.t l t e rid '· 4 7. T :i z I "~ 0. Si l ver La<e U. (ee tr'l!. 3S. ( 1 u: ! '"~ d: ~B. ~en~ ! _a :t. i3
L So~oron Gu1ch 2 j. Sneep Cree~ 36. c.-a j :I?; laKe 49. Cr-1~¥e-ch,1'"'!''~
' <. TIJS~\J!llena .:.••. S.r;we-ntna 3 7' )~) c 1. I Si te z: .. T~ : a,r,yl 1 'f,ij j6, ..,O'WI?
-J
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3:
:e 2
0
0
0
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>-
!::
(..)
~I
~
(.)
10
8
::r:
~6
0
0
0
>-
(!)
~4 z
I.U
7!5
1980
PEAK
1990
D HYDROELECTRIC
L::::::!:\] COAL FIRED THERMAL
E:ZJ GAS FIRED THERMAL
2000
• OIL FIRED THERMAL( NOT SHOWN ON ENERGY DIAGRAM
NOTE ; RESULTS OBTAINED FROM
OGPS RUN LFL 7
CHA KACHAMNA
EXISTING ANO COMMITTED
1954
20!0
0~--~---------------------------------------------------------~ 1980 1990 2000 2010
TIME
GENERATION SCENARIO INCORPORATING THERMAL
AND ALTERNATIVE HYDROPOWER DEVELOPMENTS
• MEDIUM LOAD FORECAST-FIGURE 6.4
PREVIOUS
STUDIES
UNIT TYPE
SElECTION
COAL: 100 MW
250 MW
500 MW
COMBINED CYCLE I 250 MW
GAS TURBINE : 75 MW
DIESEL : 10 MW
i r 1 ,.
'
l r ----~
PLAN
FORMULATION
OBJECTIVE
ECONOMIC
COMPUTER MODELS
TO EVALUATE
SYSTEM WIDE ECONOMICS
EVALUATION
OBJECTIVE
GAS RENEWALS
NO GAS RENEWALS
ECONOMt~ I
NO GAS RENEWALS
LEGEND
FORMULATION OF PLANS INCORPORATING ALL-THERMAL GENERATION
STEP NUMBER IN
STANDARD PROCESS
(APPENDIX A}
FIGURE 6.5
-
-
-
. I
"!! '. ; } ,_
i .,, !
t:) -~I
'·I
~.~ I
3:
~
0
0
Q
>-1-u
~I
<(
(.)
tO
8
:I:
3:6 (!)
0
8
>-
(.!)
~4 z
UJ
2
715
1980
PEAK
LOAD
LEGEND:
1990
D HYDROELECTRIC
ttiirl coAL FIRED THERMAL
e:zJ GAS FIRED THERMAL
• OIL FIRED THERMAL ( NOT SHOWN ON
NOTE: RESULTS OBTAINED FROM
OGPS RUN LME I
2000
TOTAL DISPATCHED
ENERGY
1980
:: :·: ,•:
·, :: .. :
·:: .
1990 2000
TIME
ALL THERMAL GENERATION SCENARIO
-MEDIUM LOAD FORECAST-
1895
2010
.. ;
:. "
2010
FIGURE 5.G
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. -·--------------------
7 -SUSITNA BASIN
7.1 -Introduction
The purpose of this section is to describe climatologicalt 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 climatologyt hydrology
and geology, and seismic considerations and outlines the environmental aspects.
The ·information presented has been obtained both from previous studies and the
field programs and office studies initiated during 1980 under Tasks 3, 4, 5 and
7.
7. 2 -Cl imato 1 ogy and Hydro logy
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
collected 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 humidityt precipitation, and solar radiation. Snowfall
amounts are being measured in a heated precipitation bucket at the Watana
station. Data are recorded at thirty minute intervals at the Susitna
Glacier station and at fifteen minute intervals at all other stations.
(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 Talkeetna
Mountains and the Alaskan Range whereas at Talkeetna station, at elevation
345 feet, the average annual precipitation recorded is about 28 inches.
The average precipitation reduces in a northerly direct)on 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 during the warmer months, May through October,
7-1
while only 32 percent is recorded in the winter months. Average recorded
snowfall at Talkeetna is about 106 inches. Gener~lly, snowfall is re-
stricted to the months of October through Apri 1 with some 82 percent
snowfall recorded in the period November to March.
The U.S. Soil Conservation Service (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 BasH
are genera11y lccated 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 snow courses on the Susitna glacier (see Figure 7.1). Arrange-
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
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 maximLm
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 aerial and ground reconnaissance and documentation of freeze-up am
break-up processes. This data wil1 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 mitigation measures.
(e) 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
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purposes, available streamflow records have been extended to cover the full
30 year period using a multi site correlation technique to fi '11 tht:: qaps 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 drainage basin areas.
A gaging station was established at the Watana ~am site in June 1980 and
continuous river stage d~ta is being collected. It is proposed to develop
a rating curve at the station with streamflow measurements taken durinq the
1980 and 1981 seasons. River flows wi1l 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 April) 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. The monthly
average flows in the Susitna River at Gold Creek are given in Figure 7.3.
On averege, approximately 88 percent of the streamflow r~corded 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 (ET 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 discharge~ for the
Susitna River at the gaging stations are given in Table 7.4.
The Susitna River above the confluence with the Chulitna River contriblltes
only approximately 20 percent of the mean annual 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 snowmelt 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 \vell 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 occur in the river. These floods, although smaller, can be
accompanied by ice jamming, and must be consider~d during t~e 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 wi 11 also be used to check the
accuracy of the Gold Creek Station rating curve which is important in
7-3
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....
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{g)
determining spillway design floods for the propo:~d Susitna River projects.
Multiple regression equations have been developed u~~ng physiographic
parameters of the basin such as catchment area, strc~am 1P.nqtl1, nH~an 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 facilit~es 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 h~ld 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
pdrameters and that add1tional refinement of the flood estimation technique
is warranted.
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 deqree of
uncertai r.ty.
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 in the literature ( , ) . 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
peri0ds of major tectonic deformation. The oldest rocks (250 to 300 m.y.b.p.)*
exposed in the region are volcan1c flows and limestones which are overlain by
sandstones and shales dated approximately 150 to 200 m.y.b.p. A tectonic event
appr~ximately 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
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period (65 to 100 m.y.b.p.). As a result of this faulting anrl upllft, t.h•:
eastern portion of the area was elevated, and the oldE~st volcan1cs antl c;edimt::nt.s
were thrust over the younger met amorphi cs and sediments. The major an~t} of
deformation during this period of activity was southeast of Devi 1 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 overthrusti ng from southeast to northwest. The Devi 1 Canyor1 i'lr(~ii was
probably deformed and subjected to tectonic stress during the same period, 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 vo1canics 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.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 r0cks. 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 car;yons that are evident today, particularly
at the Vee and Devil Canyon dam sites. This er·osion is believed to b•= still
occurring and virtually all streams and rivers in the region are considered to
be actively downcutting. This continuing erosi~n 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 st~eams.
The arctic c I i mate has retarded deve 1 opment of '.:opsoi 1.
Further geologic mapping of the project area and geotechnical investigation of
the proposed dam sites was initiated under the current study in 1980, and wi ~1
continuP 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 Devi 1 Canyon a:1d Watana dam sites.
However, much of the discussion is pertinent to all d~m 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 ter'll 1s 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
Fa.ult, and on the west by the Alaska Peninsula features that rnake up the
Central Alaska Range. South of the Talkeetna Mountains, the Tal: ~Ptna
Terrain is separated from the Chugach Mountains by the Castle Mou. ~ain
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Fault. The ~reposed Susitna Hydroelectric Project dam sites are located In
the western half of the Talkeetna Terrain. The easter·n h.:1lf of the region
includes the relatively inactive, ancient zone of sediments under the
Copper River Ba.s in and is bounded on the east by the Totschuncja sect ion of
the Denali Fault and the volcanic Wrangell Mountains.
Regional earthquake activity in the project area is closely related to the
plate tectonics 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 sha11ow
and deep earthquakes generated within the Benioff 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 lo,.; based on
historical records. Most of the recorded earthquakes in the area are
reported to be related t0 the Denali -Toschunda Fault, the Castle Mountain
Fault or the Benioff Zone.
Field Investigations
For project design purposes, it is important to identify the surface
expressions of potential seismic activity. Within the Talkeetna Terrain,
numerous lineaments and features were investigated as part of the 1980
seismic studies. Utilizing available air photos, satellite imagery and
aiJ~borne 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 g1aciation,
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 eithE·r 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 1 ineaments or faults that have been subjected to recent displacement
are retain~d 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
displacenent 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 ~fter review of regulatory requirements of
the WPRS, COE, U.S. Nuclear R.egul atory Commission, Federal Energy
Regulatory Commission, and several state regu1ations.
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Of the 48 candidate features~ only 13 features were judged to be signifi-
cant for the design of the project. These 13 features include f(HIY" fea·
tures at the Watana site (including the Talkeetna Fault and the Susitna
feature) and nine features at the Oevi I Canyon site. It is worth not i rHJ
that no evidence of a surface expression was observed in the vicinity of
the so-called Susitna feature during the 1980 studies. These thir·teen
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 micraseismic monitoring 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 largest being magnitude 3.7. None of the
microearthquakes recorded at shallow depths were found to be related to any
surface feature or lineament within the Talkeetna Terrain, including the
Talkeetna Fault. The depth of the Benioff Zone was distinctly defined by
Ulis data as being 36 miles below the Devi 1 Canyon site and 39 miles be1o~l
the Wi!.tana site.
(d) R~servoir Induced Seismicity
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
1 .arge reservoirs where seismic tremors under or immediate 1 y adjacent to the
res€rvoir have been correlated to periods of high filling rate. In recent
years, this subject has drawn considerable attention wit~in the engineering
and seismic community. rt is thought that RIS may be caused by the in-
creased weight of the water in the reservoir or by incteased pore pressures
migrating through and "lubricating" 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 disp1acement must be under or very near to the reservoir. The
presence of a fault with recent dispiacement has not bee~ 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 early 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
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will not control the design earthquake determination ~nd is considered only
for purposes of est·mating recurrence intervals of potential events.
Preliminary Groi~!EL_Mot ion Eva I uat ions
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 DE:nali 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 surface. 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 conservative 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 preliminary 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 u.2lg 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 magnitude 8.5,
which would generate a mean peak acceleration of U.4lg at the Watana site
ancl 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 second·s. It is evident that of these three potential
sources, the Benioff !one 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 wi 11 lead to a reduct ion 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 darn. In California, dams
are rout·ine1y designed to withstand ground mot ions from magnitude 7. 5 to
8.5 earthquakes at distances 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 at·e 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 comp.:1rable in size to Watana, could with-
stand seismic loadings comparable to those postulated for the Watana Jnd
Devil Canyon sites.
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7.5-Environmental Aspects
Numerous studies of the environmental characteristics of the Susitna 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 examination of the Susitna Basin ever under-
taken, and possibly of any comparable resource. In this section, descriptions
of ambient biological and vegetation conditions are presen~ed. These
descriptions are based on reviews of the literature as well as the preliminary
results of on-going studies.
(a) Biological
(i) Fisheries
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 Susitna River as far as the Deshka River about 40 miles
from 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 a 1 so known to occur in freshwater s 1 ougf1 s 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.
Since the Susitna is a glacial fed stream the waters are silt laden
during the summer months. This tends to restrict sport fishinq 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 Devi 1
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 ) B i g G arne
The project area is known to support species of caribou, moose, bear,
wolves, wolverine and Oall sheep.
-Caribou: The Nelchina ca~ibou herd whi:h occupies a range of about
20,000 square miles in southcentral Ala~ka has been important to
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hunters because of its size and proximity to population centers.
The herd has been studied continuously since 1948. The population
declined 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 "big bend" of the
Susitna. Calving occurred between the Oshetna River and Kosina
Creek between the 3,000 to 4,500 feet elevations. The main summer-
ing concentration of caribou occurred in the northern and eastern
slopes of the Talkeetna ~lountains 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 s p 1 it in two groups. One group was located in the
Slide Mor.--.tain-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 thr·oughout 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. Wirter
distributions are shown on Figure 7.~.
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 ~auld reduce the moose population for the area. The areas
do not appear to be important for calving or breedi~g purposes. how-
ever they do provide a winter range that could be critical during
severe winters. In addition to direct losse~. 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
Sus itna. River.
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The proposed impoundments are 1 ikely to have 1 itt le impact on the
availability of adequate brown bear den sites, however the extent
and utility of habitats utilized in the spring following emersence
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 c0nfin€d to or near
the forests found in the vicinity of the Susitna River and the major
tributaries. Utilization of the forest habitat appears most
prevalent in the early spring. In the late summer black bears tend
to move into the more open shrublands adjacent to the spruce forest
due to the greater prevalence of berries in these areas.
Most of the known active dens in the Devil Canyon area will not be
inundated although several known dens will 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) ( ). Territory
sizes for the five studied wolf packs averaged 4521fo 821 square
miles. Known wolf territories are eventually non-overlapping during
any particular year. A minimum of 40 wolves 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 although 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 Sheep: Dall 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 H·i 11 s and Mount Watana.
Since Dall sheep are usually found at elevations above 3,000 feet,
impacts will likely be restricted 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 weasel, least weasel,
muskrat and beaver. Direct innundation, construction activities and
access can be expected to generally have minimal impact on these
species.
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( i v) Birds and Non-Game Mammals
One hundred and fifteen species of birds were recorded in the study
area during the 1980 field season, the most abundant being Scaup and
Common Redpoll. Ten active raptor/raven nests have been recorded and
of these, two Ba1d Eagle nests and at least four Golden Eagle nests
would be flooded by the proposed reservoirs, as would about three
currently inactive raptor/raven nest sites. Preliminary observations
indicate a low populaiton of waterbirds on the lakes in the region;
however, Trumpeter Swans nested on a number of lakes between the
Oshetna and Tyone Rivers.
Flooding would destroy a large percentdge 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
waterbodies that appear to be important to waterfowl will be flooded,
nor will the important prey species of the upland tundra areas be
affected. Impacts of other types of habitat alteration wi 11 depend on
the type of aiteration. 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,
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) ~_g_etation
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 Aiaska Range on the north ard 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 Oshetna River, are steep and covered
with conifer, deciduous and mixed conifer, .and deciduous forests. Flat
benches occur at the tops of these banks an~ 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 Susitna 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 because
of intergradations. The area between the i~aclaren River and the Denali
Highway along the Susitna River js covered with woodland and open spruce
stands. Farther east. the area has more low shrubland cover. The
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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 i~aximum pool elevations are required, the Devil Canyon (mapped
at the 1500 ft elevation) and Watana (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 veqetated (Table 7.7).
A total of 18,109 ha of vegetation will be lost if all borrow areas
(outside the impoundment areas) are also totally utilized. Borrow sites
may eventually be revegetated, however. The 18,109 ha of impacted
vegetation represents roughly 1.2 percent of the total vegetated area in
the Upper Susitna River Basin.
Assuming maximum impact in the impoundment and borrow areas, the
vegetation/habitat types which will be lost (and the apparent percent each
is of the total available in the entire basin) are presented in Table 7.7.
Problems created by comparing maps of two different scales resulted in
apparent percentages of overlap which are h;ghly inflated for the
comparison of birch forests in the impact at·eas with that of their
availability of the overall basin. However, it can 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 railroad will destroy an additional 150 to 300 ha 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 types to be affected are mat and cushion
tundra, sedge-grass 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 Resources
The archeological ~tudy presently being conducted as part of the Susitna
Hydroelectric program is the only intensive archeological survey to flave
been conducted in the Upper Susitna Basin. The archeological data gathered
from this study wi 11 greatly add i nformati 011 and understanding of
prehistoric native populations in central Alaska.
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The 1980 archeological 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 will locate
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 tr1e summer of 1981 and national
register criteria which determine eligibility for the national register of
historic places.
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 conducred 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 would receive direct
impact and the other half indirect impacts. The Watana Creek tertiary
basin would also be inundated.
Since few reconnaissance surveys have been conducted outside the Devil
Can_yon/Watana Dam study area, the precise number of sites that would be
impacted by a High Devil 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 additicn, there is a high
potential for many more sites along the lakes, streams clnd rivers in this
easterly region of the Upper Susitna River Basin. 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 Devi 1
Canyon/Vee Scheme than the Watana/Oevi 1 Canyon Scheme.
(d) Socioeconomics
~ As part of the Susitna Hydroelectric program a socioeconomic program has
baen implemented to identify the socioeconomic factors that will be
affected and to determ~ne the extent to which they will 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 Fai~banks. Preliminary 1980
census figures indicate the Railbelt conta~ned 280,511 people, 71
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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 roun(i
units. Vacancy rates for Mat-Su Borough, Fairbanks, and Ancnoragt!
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 ha~;
1,141 recreational units.
(ii) Economics
Both Anch·Jrage 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 few the
Railbelt area residents is a further manifestation of the regions two
relatively concentrated population centers and of the high degre1! of
economic diversity, as well as levels of demand for goods and
services, which are substantially higher than in most other part; of
Alaska. The importance of construction is largely due to the hi 1h
level of expansion experienced by the Anchorage and Fairbanks art!as
si nee 1968. This growth was partly attributable to the trans-A 1 ,lska
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 transpo~ta
tion centers, not only for the Southcentral Railbelt area but for the
rest of the State as well. The Port of Anchor-1ge handles most of the
waterborne freight moving into s11uthcentral and northern Alaska.
Internationa~ airports at Anchora~e and Fairbanks serve as huos ft•r
commercial air traffic throughc!..!t. Alaska and are important stopov~·rs
for major internatin~al a~r 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 Alas~a Railroad to
more remote areas •
Valdez is the states largest port handling an annual tonnage of 60
million tons. Ninety-seven per(:ent of this 1nvolves the shipment nf
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 emp l.oJTnent they generate in the region.
7-15
-
(e)
--
Most agricultural activities in the Southcentral Railbelt area take
place in the Matanuska, Susitna, and Tanana Valleys. The potential
for agr·icultural in these areas of Alaska is considered favorable~
although development of the industry has not been extensive.
ColllTlerc·ial 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 T~nner 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.
Transport at ion
( i )
( i i )
( 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
mi 1 es. The Federally constructed and operated A 1 ask a Rail road 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 ?26-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-mi le
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.
Air. In addition to major airlines within Alaska, there are numerous
Siiidll commerical operators plus the highest per capita r·atio of
private aircraft in the nation. Many small remote landing strips are
scattered throughout the Susitna basin, and float planes utilize many
1 akes and str·eams to ferry freight and passengers to the remote
ba.ck-country areas. In many areas of the State, the on 1 y access is
provided by the airplane.
7-16
(i v) Other Forms of Trans.portati~. ATVs and other types of off-road
vehicles provide transportation into areas in the upper Susitna basin
where there are no developed roads. Several developed trails are
shown on maps of the upper basin. Trails are utilized by ATVs, trai 1
bikes, hikers, horseback riders, and winter travelers.
Shallow-draft river boats, small boats, caroes, 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 m2ny single cabin settlements throughout the
basin.
Most of the existing structures 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
some 21 structures. A significant concentration of residences, cabins or
other structures are found near the Otter lake area, Portage Creek, High
Lake, Gold Creek, Chuni 1 a Creek, Stephan Lake 9 Fog Lake, Tsusena Lake,
Watana Lake, Clarence 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 also important uses. There are
numerous tr ai 1 s throughout the basin used by dog s 1 ed, snowmobi 1 e and
ATV's. Air use is significant for many lakes providing landing Greas 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 project 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
.... ) 1 ]
TABLE 7.1 -SUMMARY OF CLIMATOLOGICAL DATA
MEAN MONTHLY PRECIPITATION IN INCHES
STATION JAN fEB MAR APR MAY JUNE JUlY AUG SEPT OCT NOV OEC ANNUAL
Anchorage 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 0.75 0.76 11.11
Hatanuska Agr.
Exp. Station 0.79 0.63 o.:;~ 0.62 0.75 1.61 2.40 2.62 2.31 i.}9 0.93 0.93 15.49
McKinley Park 0.68 0.61 0.60 0.~8 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 o.,n 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
Anchorage 11.8 11 .a 23.7 35.3 46.2 54.6 57.9 55.9 48.1 34.8 21.1 13.0
Biq 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
Hatanuska Agr.
ExJ!.. Station 9.9 17 .a 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 J.O 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
~-·
Source:
Reference:._ __ _
TABLE 7.2-RECORDED AIR TEMPERATURES AT TALKEETNA AND SUMMIT IN °F
Taii<eetna !lumm1t
"""' I 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 2'1.2 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
r""" MARCH
APRIL
r""" MAY
JUNE
JULY
AUGUST
SEPTEMBER
OCTOBER
""""
NOVEMBER
f!"" DECEMBER
ANNli.:'l.. -cfs
....
TABLE 7.4-AVERAGE ANNUAL AND MONTHLY FLOW AT GAGE
IN THE SUSITNA BASIN
STATION (USGS Reference Number
Susitna River Susitna River Susitna Rivr:.r Maclaren River
at Gold Creek Near Cant we 11 Near Denali Near Paxson
(2920) (2915) (2910) (2912)
% Mean(cfs) % Mean(cfs) "' Mean(cfs) "' Mean(cfs) "' ·~
1 1,43B 1 824 245 90
1,213 722 1 204 78
1,085 692 187 1 71
1,339 853 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 ?.7 3,171
-
19 21,950 20 14,660 24 7,813 22 2,557
12 13,770 10 7,800 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
F"
TABLE 7.5 -FLOOD PEAKS AT SELECTED GAGING STATIONS ON THE SUSITNA RIVER
Annual Flood Peaks -cfs
Drainage Mean
il""' Station (USGS No.) Area-mile2 Annual 1:100 yr 1:10,000 yr Peaks -cfs
Gold Creek Gage ( 2920) 6,160 53,000 118,000 185 ,rmn 106,!101)
Cant we 11 Gage (2915) 4,140 33,700 68,1'100 118,!100 61 '70!1
Denali Gage ( 291 0) 950 17,800 43,600 63,000 36,600
"""'
7-22 -
r
r
-I
-
TABLE 7.6-SUSPENDED SEDIMENT TRANSPORT
Source:
Station
Susitna at Gold Creek
Susitna near Cantwell
Susitna near Denali
Maclaren near Paxson
Reference
7-23
Sediment
Transport
(Tons/xear)
8,734,000
5,129,000
5,243,000
614,000
Initial
Unit Weight
(Lb/ft 3 )
65.3
70.6
70.4
68.6
........
I
N
~
-l
TABLE. 7. 7 -DiffERENT VEGETAHON TYPE.S FOUND IN TH£ SUSITNA BASIN
Hectares of vegetation types to be impacted compared with total hectares of those types.
I~oundments Borrow Areas
Upper Susitna
Devil Canyon Watana A c D f H River Basin --------------------~~~~~~--~~~------~--------~~-------~~--------~--------~------·
Woodland spruce 162 (0.09)1 4766 (2 • .53) 228 (0.12) 77 (0.04) 1.5 (0.01)
Open spruce 862 (0. 73) 38.54 (3.24) 48 (0.04) 7 (0.01)
Open birch 73 (0. 73) 318 (2.85)
Closed birch 470 2 4912 12
Open conifer-deciduous 300 (1.28) 1329 (5.68) 19 (0.08) 9 (0.04)
Closed conifer-deciduous 758 (4.75) 869 (.5.44) 2 (0.01)
Open balsam poplar 73
Closed balsam poplar 103 z3
Wet sedge grass 12 (0.2.5) 100 (2.07) 6 (0.12} 1 (0.02)
and cushion tundra 78 (0.12)
Tall shrub 19 (0.01) .580 (0.4.5) 18 (0.01) 23 (0.22) 8 (0.01)
Birch shrub 58 (0.17) 474 (1.41) 18 (O.OS) 92 (0.27} 73 (0.22)
Willow 16 (0.015) 55 (0.52)
Low mixed shrub 6 (+) 78S (0.15) 101 (0.02) 11J (0.02) 109 (0.02) 55 (0.01)
Lakes •J (+) 47 (0.22) 3 (0.01) 1 (+)
Rivers 835 (.5.69) 2106 (14.3.5) 10 (0.07) 6 (0.04)
Rock 14 (0.01) 63 {0.06) 1 (+)
Total Areas 3603 (0.22) 1.5839 (0.97) 500 (0.03) }22 (0.03) 228 (0.01) 71 (+)
NOT£5:
Numbers in parentheses are the percent of the vegetation as found in the entire Upper Susitna Basin.
227 (0.12)
12.5 (0.11)
94 (0.40)
7 (0.07)
46 (0.01)
499 (0.03)
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 J 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
(•tapped at a scale of 1 :2.50,000), because the basin was mapped at a much smaller scale, and many of the closed bit'ch 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.
5 0 5 15 I I I I
SCALE IN MILES
~
T'I'ONE & DAMSITE
CANTWELL • STREAMGAG£
SUMMIT \J CLIMATE
\)SUMMIT
\ l' \.,. ......
' \.
\
(,
~
(
DATA COLLECTION STATIONS \
-~, ----1 1
PAXSON[:}.
GULKANA\J _/ ,... -----------
)
1 [i] ' ••In ./-v---v FIGURE 7.1 II ll -'----------------------------------------~ L-----~----------------------------
r
-
F
i
r
'
-
COOK INLET
SUSITNA RIVER
DEVIL
CANYON SITE
GOLD CREEK
WATANA
SITE
PARKS HIGHWAY BRIDGE
GAGING STATION
SUSITNA GAGING STATION
AVERAGE ANNUAL FLOW OIS1"RIBUTION
WITHIN THE SUSITNA RIVER BASIN
F!GURE 7.2
7-26
] 1
50,000
LEGEND
0 40,000 WETTEST YEAR -1962
z
0
0 AVERAGE YEAR w
rJ)
0:: w
0.. DRIEST YEAR -1969
....... .... 30,000 I
N w
'-J w
IJ...
u
m
:::)
(..)
~ 20,000
0
..l
LL.
:'!:
<(
w
tk:: ....
(I)
10,000
APR MAY JUN JUL AUG SEP OCT
0
FEB MAR JAN NOV DEC
MONTHLY AVERAGE FLOWS IN
THE SUSITNA RIVER AT GOLD CREEK
FIGURE 7.3
r
, .....
-
T
!I
N
0
~~'~1r~F~~~~rx·~-~~---~----~~idi
I&J
UJ
>-0::
<(
0 z :::>
0
CD
::t: .... a:
~~~~--~--·----------------~g
CE.NOZOIC
QUATERNA r----1
I ..._ __ _
TERTIARY
~r-..--.
I + + ..... _ .. ~
MESOZOIC
CRETACEO
~~~
JURASSIC
ffiTIIfi
REGION A
.~'----------------------------------------------------------------------------------------------------------~._----~
CENOZOIC
~ QUATERNARY
....
r----'1
: t """"---....
TERTIARY
p-:-.r;;-::'1
u.!d.l.~1
!'~"-.,-,.,
I + + t ~.,_...___,
~ESOZOIC
CRETACEOUS t:---=---=--) ~:..---------.. L-£:-::..;: -£:-.J:
JURASSIC
amniG
LEGEND
UNDIFFERENTIATED SURFICIAL DEPOSITS
UNDIFFERENTIATED VOLCANICS S SHALLOW
INTRUSIVES
GRANODIORITE I
BIOTITE-HORNBLENDE GRANODIORITE 1
BIOTITE GRANODJORITE
,f"
SCHIST, MIGMATITE, GRANITIC ~OCKS
UNDIVIDED GRANITIC ROCKS
rl'\7\1\lrl'il
~~~~~
TRIASSIC
r-~""7i"".:J
~:!!-"..!..:!
PALEOZOIC
THRUST FAULT --y--T•
INTENSE SHEARING
..
AMPHIBOUTES, GREENSCHIST, f()I;JIWEO DIORIT£
BASALTIC METAVOLCANIC ROCKS, IIETABASALT
AND SLATE
BASALTIC TO ANOESITIC METAVOLQIIIIICS LOOAU.Y
INTERBEDDED WITH MARBLE
TEETH ON UPTHROWN SlOE ,DASHEDWHERE ·INFERfi:ECi
DOTTED WHERE CONCEALED " i
MAFIC INTRUSIVES ••• "\1 ••• ·v·· • POSSIBLE THRUST FAULT, TEETHCIIUPTHROWN
SIDE
PROPOSED DAM SJTES
AF.GILLITE AND LITHIC GRAYWACKE
GRANODIORITE, QUARTZ DIORITE, TRONDHJEMITE
~tGIONAL GEOLOGY
-
-
....•
0 z
1.1.1
t.? w
..J
7-29
> ....
Ui z
1.1.1
Q
0 a::
1.1.1
N
> l-
Ui z
1.1.1
Q
3::
0
-1
> l-
Ui z w
Q
:r
t.? :
0
CD
0')
• 0::
LIJ
Ql
::!
LIJ > 0 z
LIJ
CJ)
0
0
::E
LL..
0
(/)
1.&.1 -.... -(I) z
LIJ
0
w > -....
<t
...J
LIJ
0::
-...1
I w
0
1
LOCATION MAP
MODIFIED FROM REFERENCE (
WINTER
1 1 ....... l
DISTRIBUTION OF
1
10 0 10 30
SCALE IN MILES
MOOSE -MARCH, 1980
FIGURE 7.6
......,
I w ......
LOCATION MAP
.. 1-
LE~:
~ WATANA PACK
J?Zj TYDNE PACK
([[ill]J SUSITNA PACK
~ TOLSONA PACK
r--,
I I
L--.J SUSPECTED PACK
10 0 10 30
SCALE IN MILES
LOCATION AND TERRITORIAL BOUNDARIES OF WOLF PACKS -1980
FIGURE 7.7
-
-
-
-
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 the 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 Watana/Devil Canyon dam project, is com-
pared to alternat·ive methods of generating Railbelt energy needs including ther-
mal and other potential hydroelectric developments outside the Susitna Basin on
the basis of technical, economic, environmental and social aspects.
8.1 -Terminology
In the description of the planning process, certain plan components and process-
t;;:; are frequently discussed. It is appropriate that three particular terms be
clearly defined:
(a) Dam Site
(b) Basin Development
Plan
(c) Generation
Scenario
-An individual potential dam site in the Susitna Basin,
equivalent to "alternative" referred to in the generic
process a "candidate" or
-A plan for developing energy within the basin involv-
ing one or more dams each of specified height and cor-
responding power plants of specified capacity. Each
plan is identified by a plan number and subnumber in-
dicating the staging sequence to be followed in devel-
oping the full potential of the plan over a period of
time. These are equi va 1 ent to the 11 pl ans" 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 requir-
ed 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, 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 evaluation.
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 it became available, this data was fed
into the screening and plan formulation and evaluation studies.
The second objective is satisfied by comparing generation scenarios with the
selected Susitna Basin development plan with alternative generation scenarios
including all thermal and a mix of thermal plus alternative hydropower develop-
ments. The selection and screening of alternative hydropower thermal units and
developments is discussed in Sections 6.4 and 6.5 respectively. The plan formu-
lation step which involves developing the alternative generating scenarios is
outlined in Section 8.7 below. The final evaluation of the plans is also dis-
cussed in Section 8.7.
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 Gold Creek
(see Figure 4.1). These sites are listed below:
-Gal d 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
-
r--Oenal i
r
i
-
-Butte Creek
-Tyone
Figure 8.2 shows a longitudinal profile of the Susitna ~iver 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 as the down-
stream site would inundate the upstream site.
All relevant data concerning dam type, capital cost, power, and energy output
was assembled and is summariz.ed in Table 8.1. For the Devil Canyon, High Uevil
Canyon, Watana, Susitna III, Vee, Maclaren and Denali sites conceptual engineer-
ing 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 ~stimates of the potential average energ~
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, ~igh Devil 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 Denali and Maclaren produce substantially higher cost energy than the other
sites but can also be used to increase 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 de-
veloped for the current studies (Table 8.2). These results show that the cur-
rent estimates are generally slightly higher than previous estimates and, except
in the case of Vee, differences are within 15%.
At Devil Canyon current total development costs are similar to the 1978 COE es-
timate~. 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
relatively good agreement. Costs developed for the High· Devil Canyon dam site
are very close while those at Watana exceed previous estimates by about 15%. A
major difference occurs at Vee where current estimates exceed those developed by
the COE by 40%. A large 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 foun~ation excavation and treatment that
have been assumed. This additional foundation work is consistent with a stan-
dard set of design assumptions used for developing all the site layouts reported
here. Section 8.4 and Appendix D discuss these aspects. in more detail.
8-3
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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 either being rela-
tively unacceptable, significant or moderate.
-Unacceptable Sites
Sites in this category are classified as unacceptable either because
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 possible 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 would 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 waterflow 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 Denali Highway is relatively close by,
this area is not as isolated as the Upper Tyone River Basin. It is
still very sensitive in terms of potential impact on big game and
waterfowl. Butte Creek, Denali, Maclaren, and to a lesser extent,
Vee sites fit into this category.
8-4
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(b)
-Sites With Moderate Impact
Sites between Devil Canyon and the Oshetna River have a lower paten··
tia1 environmental impact. These sites include the Devil Canyon,
High Devil Canyon, Devil Creek, Watana, 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 alternati~e
dam locations can be treated as one site for project definition studJ
purposes. The two sites which fall 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 sitt!.
(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
development in the Susitna Basin to an average annual energy produc-
tion in the range of 500 to 1000 GWh. The upstream sites such as
Maclaren, Denali, Butte Creek, and Tyone do not meet this minimum
energy generation criteria.
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 th s
process are as follows:
-The ''unacceptab 1 e s ite 11 environment a 1 category e 1 imi nated the Gold Creek.'
Olson, and Tyone sites.
-The alternative sites category eliminated the Devil Creek and Butte Creek
sites.
f--No additional sites were eliminated for failing to meet the energy con-
tribution criteria. The remaining sites upstream from Vee, i.e.
Maclaren and Denali were retained to ensure that further study was direc··
-ted at determ1ning the need and viability of providing flow regulation in
the headwaters of the Susitna.
-8.5 -Engineering Layout and Co.;t Studies
In order to obtain a more uniform and reliable data base for studying the seven
sites remaining, it was necessary to develop engineering layouts for these sites
....
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8-5
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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 1 ayouts are consequently concep-
tual in nature arid 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 of the order of plus or minus 30%.
(a)
(b)
Design Assumptions
In order to maximize standardization of the layouts, a set uf basic design
assumptions were developed. These assumptions cover geotechnical, hydro-
logic, hydra.ulic, <.:ivil, mechanical, and electrical considerations and were
used as guidelin.~s to determine the type and size of the various components
within t·he 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 r-egarding site conditions was avail ab 1 e. Broad
assnmptions were made on the basis of the limited data and those assump-
t·lons and the interpretation of data has been conservative.
It was assLHlled that the relative cost differences between rockfill and con-
cret,e 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 Devil 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 cons i dera-
tion of dam fill rates compared to concrete rates at alternative sites.
General Ar·ran.gements
A bri·ef description of the general arrangements developed for the various
sit.es is given below. Pla.tes 1 to 7 illustrate the layout details. Table
8.3 s.ummartze.s 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 com-
ponent structures.
(i l PeviLCac~J.ron (Plate 1)
-Standard Arrangemf:!nt
The develo~ent at Devil Canyon is located at the upper end of the
canyon corresponding to the narrowest point. It consists of a rock-
fill dam, single spillway, power facilities incorporating under-
ground powerhouse. and a tunnel diversion.
The rock.fill dam rises above the valley on the left abutment and
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terminates in an adjoining saddle dam of similar construction. The
dam rises 675 feet above the lowest foundation level with a crest
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 rackfill shell. Part of the shell will come from excavation
at the site but the majority will be blast rack from local quarries.
It is anticipated that care and filter materials will also be avail-
able locally. The core is found on sound bedrock, and full founda-
tion treatment is a 11 owed for in the form of contact grouting, cur-
tain grouting, and drainage via a network of shafts and galleries.
All alluvium and overburden material is removed from shell founda-
tion 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 fo 11 owed by construction of a so 1 i d concrete p 1 ug
within the tunnel in line with the main dam grout curtain. Subse-
quent controlled downstream releases occur via a small tunnel bypass
located at the gate structure and a Howell Bunger valve housed with-
in the concrete plug.
The spillway is located 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 Maximum
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. It consists of four integrated units, each serving
individual tunnel penstockso Each unit has three outlets at differ-
ent levels allowing for various levels of drawoff and corresponding
temperature control of releases from the seasonally fluctuating res-
ervoir. Each outlet is controlled by a pair of vertical lift wheel-
ed 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 powerhouse 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 of 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 gates required to isolate the individual
draft tubes from the conunon downstream manifold and tailrace tunnels
during maintenance. The contr·ol room and offices are situated at
the surface adjacent to a surface switchyard.
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-Staged Powerhouse
As an alternative to the full power development, a staged powerhouse
alternative has also been investigated. 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 construc-
ted together with concrete foundations for the future units, pen-
stocks 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 con-
struction of the corresponding penstocks and tailrace tunnel for two
new 100 MW (or 150 MW) units. Civil, electrical, and mechanical in-
stallation for these units would also be c0mpleted within the power-
house area, together with the enlargement of thP. surface switchyard,
during the second stage.
(ii) Watana (Plates 2 and 3)
-Standard Arrangement (see Plate 3)
For initial comparative study purposes, the dam at Watana is assumed
as a rockfill structure located on a similar alignment to that pro-
posed 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. ·che 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 twin concrete lined tunnels located within
the rock of the right abutment. Rockfill cofferdams, also with im-
pervious cores and appropriate cutoffs, are 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 Devi 1 Canyon.
The spillway is located on the right bank and is similar in concept
to that at Devil Canyon with an intermediate and terminal stilling
basin.
The power facilities are located within the left abutment with s1m1-
l ar intake, underground powerhouse and water passage concepts to
those at Devil Canyon. The power facilities consist of four 200 MW
turbine/generator units giving a total output of 800 MW.
-Staging Concepts
As an alternative to initial full development at l•atana, staging al-
ternatives have been investigated. These include staging of both
dam and powerhouse construct ion. Staging of the powerhouse wou 1 d be
similar to that at Devil Canyon, with a Stage I installation of 400
MW and a further 400 MW in Stage II.
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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 being appropriately raised and additional rock-
fill being placed on the downstream face. It is assumed that before
construction commences the top 40 feet of the first stage dam is re-
moved to ensure the complete integrity of the impervious core for
the raised dam. A second spillway control structure would be con-
structed at a higher level and incorporate a downstream chute lead-
ing to the Stage I spillway structure. The original spillway tun-
nels 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. How this can be accomplished is discussed 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:
-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.
-Modification of the turbine-generator rotational speed for the
final stage of operation.
-Replacement of the turbine runner for the final stage of opera-
tion.
-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
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( i i i)
penalty in one or perhaps both stages of operation. Unless the head
change is relatively small, the energy loss due to reduction in
efficiency would outweigh 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
the first stage operation, the unit speed may be selected slightly
lower than normal to avoid excessive speed for the higher head oper-
ation. The generator speed change can be accomplished by changing
the stator winding connections and also 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 a 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 distributor to accommodate both runners with-
out 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 which will be available 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 drawdown
conditions under both stages. Option one would not in this case be
appropriate because of the large range in head in'volved. 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
Watana. Preliminary analyses indicate that of the two options re-
maining, the third would provide the more cost effective solution
for Watana. However, should staged deve 1 opment appear economic,
more detailed studies would be required for the selection of gen.~r
ating equipment. This refinement is not expected to significantly
affect the overall economics of the staging concept, and therefore,
is not considered necessary for this ph3se of the study.
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 Devil Canyon
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(iv}
and 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.
Susitna III {Plate 5)
The development is comprised of a rockfill dam with an impervious
core and 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.
An underground powerhouse of 350 MW capacity and the two diversion
tunnels are located on the left bank.
(v) Vee (Plate 6)
(vi)
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-
side red ..
As 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 over-
flow 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 downstream of the
main dam. The intake is founded 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 arf' provided on the right
bank.
Maclaren (Plate 7)
The deve 1 opment consists of a 185 feet high earthfill 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. Diversion 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.
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(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 was 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 mob i1 i zat ion 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 Denali ~hown 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:
-Devi 1 Canyon.
-High Devil Canyon.
~ -Watana.
-Susitna III.
-Vee.
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In addition, the following two sites should be considered as candidates for
supplementary upstream flow regulation:
-Maclaren
-Denali
To establish very quickly the likely optimum combination of dams, a 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-
mental advantages by replacing the Devil Canyon dam by a long power tunnel and a
development plan involving the two most economic dam sites, High Devil 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
discussed below, environmental considerations are incorporated into the further
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 Programming (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 power 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 power and
energy demand.
A detailed description of the model as well as the input and output data is
given in Appendix E. A summary of this information is presented below:
( i) Input Data
Input data to the model takes the following form:
-Streamflow: In order to reduce the complexity of the mode 1, a year
1s d1vided into two periods, summer and winter, and flows are speci-
fied for each. For the smaller dam sites such as Denali, Maclaren,
Vee, and Uevil Canyon which have 1 itt le or no over year storage capa-
bility, only two typical years of hydrology are input. These corres-
pond to a dry year (90 percent probability of exceedence) and an
average year (50 percent probability of exceedence). For the other
1 arger sites, the full thirty years of hi stori ca·l summer and winter
flows are specified.
8-13
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-Site Characteristics: For each site, storage capacity versus cost
curves are provided. These curves \~Jere developed from the
engineering layouts presented in Section 8.4. Utilizing these
layouts as a basis, the quantities for lower level dam heights wer~e
determined and used to estimate the costs associated with these
lower leve1s. Figures 8.4 to 8e6 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.
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 energj 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 shmm on Tab 1 e 8. 5
are around 10 percent which is similar to the accuracy that can be
expected from the screening mode 1.
-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
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-For energy requirements of between 3500 and 5250 Gwh the
combinations of either Watana 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 Watana/Devil
Canyon option by 11 percent which is within the accuracy of the
model.
-The total energy production capability of the Watana/Devil Canyon
developmeni·'; is considerably 1 arger 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.
Tunnel Scheme
A scheme involving a long power tunnel could conceivably be used to replace
the Devil Canyon dam in the Watana/Devil Canyon Susitna uevelopment plan.
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 avoiding inundation of Devil 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 dam reservoir and
associated powerhouse:
-Power tunnel intake works.
One or two power tunnels of up to forty feet in diameter and up to thirty
miles in length.
A surface or underground powerhouse with a capacity of up to 1200 MW.
-Are-regulation dam if the intake works are located downstream fr·om
Watana .
-Arrangements for compensation for loss of flow in the bypassed river
reach.
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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 the~e 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, there-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 HUU 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 tunnels to the powerhouse at Devil Canyon with an installed
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 Watdna powerhouse installed capacity for this scheme is 800
MW, as for the Watana-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
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i
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(c)
(d)
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 lppears 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 analysis using both higher and lower tunnel costs have been
conducted.
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 was
therefore developed to assess the potential for developing these two sites
together. For this scheme, the Watana dam would be developed to its full
potential. However, the High Devil Canyon dam would be constructed to a
crest elevation of 147n feet to fully utilize the head downstream from
Watana.
Costs for the lower level High Devil Canyon dam were developed by assuming
the same general arrangement as for the higher version shown in Plate 4 and
appropriately adjusting the quantities involved.
Selected Basin Development Plans
The essential objective of this step in the detelopment selection process
is defined as the identification of those pl ar:s which appear to warrant
further more detailed evaluation. The results of the final screening pro-
cess indicate that the Watana/Devil Canyon a,,d the High Devi 1 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 sever-al 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 consistant with the total development size,
only staging of the two larger developments, i.e. Watana and High Devil
Canyon, is considered. The basic staging concepts adopted for these deve 1-
opments involve staging both dam and powerhouse construction or alterna-.
tively just staging powerhouse construction. Powerhouse stages are cons 1 d-
ered in 400 MW 1ncrements.
8-17
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Four basic plans ~re 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 involvir:g
a different staging concept.
(i)
( i i)
(iii)
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.
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 Subpl an .. the construction of tiigh 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.
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 tunne 1. A tot a 1 of 300 MW
would be installed at the end of the tunnel and a further 30 MW at
there-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 aoo· MW powerhouse at Watana
is staged.
8-18
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(iv) Plan 4
This single plan was developed to evaluate the development of the two
most economic dam sites, Watana and High Devil Canyon~ jointly. Stage
1 involves constructing Watana to its full height with an installed
capacity of 400 MW. Stage 2 involves increasing the capacity at
Watana to 800 MW. Stage 3 involves constructing High Devil Canyon to
a crest elevation of 1470 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 dCll11 is added down-
stream of High Devi 1 Canyon. This dam would 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 Port age Creek site.
8.7 -Evaluation 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-
tially undertaken to determine broad comparisons of the available alternatives.
This was followed by appropriate adjustments to the plans and a more detailed
eva 1 uat ion and compar i son •
{a) Pre 1 iminarx Eva 1 uat i ens
Table 8.9 lists pertinent details such as capital costs, construction per·-
iods and energy yields associated with the selected 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. All
the model runs incorporate preliminary environmental constraints. Seasonal
reservoir drawdowns 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 f~om each reservoir are maintained
·at all times to ensure a11 river reaches remain watered. These minimum
discharges were set approximately equal to the seasonal average natural low
flows at the dam sites.
The model is driver. by an energy demand which follows a distribution cor-
responding to the seasonal distribution of the total system load as out-
lined in Section 5, Table 5.10.
The mo.del 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 fai 1 ures in the 30-year period were 1 imited 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 appr·oximately to the 95 percent level of assurance.
A more detailed description of the model~ the model runs~ and the average
mpnth1y energy yields associated with the development plans is given in
Appendi J< F.
8-19
(b)
-
A range of sensitivity runs was conducted to explore the effect of the res-
ervoir drawdown limitation 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.
Plan Modifications
In the process of evaluating the schemes, it became apparent that there
~auld be environmental problems associated with allowing daily peaking op-
~rltions 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,
are listed in Table H.l1.
The brief description of the changes that were made are as follows:
( i) E1 P 1 ans
For Subplans 1.1 to 1.3 a low temporary re-regu1ation dam is con-
structed downstream from Watana during the stage in which the generat-
ing capacity is increased to 800 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 mil-
lion has been made to cover any additional costs associated with this
approach.
I
]
1
]
··~
In the final stage, only 400 MW of capacity is added to the dam at J
Devil Canyon instead of the original 600 MW. Reservoir operating
rules are changed so that Devil Canyon dam acts as the re-regul at ion 1: ..
dam for Watana. 1
(ii) E2 Plans
For Subplans 2.1 to 2.3 a permanent re-regulation 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 estdblished. This plan is similar to
E2.3 except that there-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 Devi 1 Canyon is
increased to 800 MW, i.e. during Stage 2.
(iii) E3 Plan
The Watana tunnel development 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 a re-regulation dam
downstream from Watana during stage 2. As for the El plans, it has
been assumed that it waul d be pass i b 1 e to incorporate this dam as part
of the diversion arrangements at the High Devil Canyon site, and an
allowance of $100 million has been made to cover the costs.
The energy and cost informaton presented in Table 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
evaluations basically reinforce the results of the screening model,
that is, for a total energy production capability of up to approxi-
mately 4000 Gwh, Plan E2 (High Devil Canyon) provides the most eco-
nomic energy while for capabilities in the range of 6000 Gwh, Plan El
(Watana-Devil Canyon) is the most economic.
The plans listed in Table 8.11 are subjected to a more detailed analy-
-sis in the following section.
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(c) Eva 1 uat ion Cri terj a and Method a logy
The approach to evaluating the various basin development plans described
above is twofold:
For determining the optimum staging concept associated with each basic
plan (i.e. the optimum subplan) economic criteria only are used and the
least cost staging concept is adopted.
-For assessing which plan is the most appropriate, a more detailed evalua-
tion process incorporating economic, 6nvironmental, social, and energy
contribution aspects are taken into account.
Economic evaluation of any Susitna Basin development plan requires that the
impact of the plan on the cost of energy to the railbelt area consumer be
assessed on a systemwide basis. As the consumer 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 computer 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 contained in Section 5,
Tab 1 e 5 . 10) •
-Load duration curves (as outlined 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 growth 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 runs is presented in
Appendix G.
As discussed in Section 1.4, the basic economic analyses undertaken in this
study incorporate 11 real" discount and escalation rates. The parameters
used are summarized in Table 8.12. The economic lives listed in this table
are the same as the assumed economic lives outlined in Section 6.2.
~ (d) Initial Economic Analyses
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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
installed 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 high 1 ights of the results in Tab 1 e 8.13 can be summarized as fa 11 ows:
(i) Plan E1 -Watana-Devil Canyon
Staging the dam at Watana (P.lan E1.2) is not as economic as con-
structing it to its full height (Plans E1.1 and E1.3). The economic
advantage of not staging the dam amounts to $180 mill ion in 1980.
-The results indicate that to the level of analysis performed, there
is no discernable benefit in staging construction of the Watana
powerhouse {Plans £1.1 and £1.3). It is considered likely, however,
that some degree of staged powerhouse construction will ultimately
be incorporated due to economic considerations and also because it
8-22
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(e)
provides maximum flexibility. For current planning purposest it is
therefore assumed that the staged powerhouse concept, i.e Plan El.3t
is the most appropriate Watana-Devil Canyon development plan.
Additional runs performed for variations of Plan £1.3 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
constrL:tion 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 £1.4 indicates that should the powerhouse size at Watanabe
restricted to 400 MW the overall system cost would increase by $40
mi 11 ion.
(ii) Plan E2 -High Devil Canyon-Vee
(iii)
(iv}
-Plans E2.1 and E2.2 were not analyzed as these are similar to £1.1
and E1.2 and similar results can be expected.
The results for Plan £2.3 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 were limited to 400 MW.
Plan E3
The results for Plan E3.1 illustrate that the tunnel scheme versus the
Devil Canyon dam scheme (El.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 reason, a sensitivity analysis was
made as a check to determine the affect of halving the tunnel costs.
This analysis indicates that the tunnel scheme is still more costly by
$380 mi 11 ion.
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.
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
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The results for low load forecasts illustrate that the most viable Susitna
Basin development plans include the 800 MW plans, i.e. Plan E1.5 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, i.e. either Watana or H·Jgh Devil
Canyon. In this case, the Watana only plan is $90 million more costly than
the High Devil Canyon plan.
Plan E3 variations are more costly than both Plans E1 and E2.
For the high load forec~sts, the results indicate that the Plan E1.3 is
$1040 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 E4. 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 :riteria are used to evaluate the shortlisted basin development
plans. They generally contain the requ1rements 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 full considera-
tion is given to the total basin energy potential that is developed by the
various plans.
( i )
( i 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.
Environmental:
A qualitiative assessment of the environmental impact on the ecolog-
ic, 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 asses-
sment of the plan.
( i i i ) Socia 1 :
This attribute includes determination of the potential non-renewable
resource displacement, the impact on the state and local economy, and
the risks and consequences of major structura 1 failures due to sei s-
mic events. Impacts on the economy 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
~ quantative while others are qualitative. Overall evaluation •S 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. In 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
decisi9n 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 judgement decisions made.
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i
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) Devil Canyon Dam Versus Tunnel
The first step in the process involves the evaluation of the Watana-
Devil Canyon dam plan (E1.3) 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 OGP5
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.
~anomie Comparison
From an economic point of view, the Devil Canyon aam scheme is
superior. As summarized in Tables 8.16 and 8.17, the dam scheme
represents a savings of $680 million. For a low demand growth
rate, this cost saving would be reduced slightly to $610 million.
Even if the tunnel scheme costs are halved, the total cost saving
would still amount to $380 million. As highlighted in Table 8.17,
consideration of the sensitivity of the basic economic evaluation
to potential changes in capital cost estimate, the period of eco-
nomic analysis, the discount rate, fuel costs, fuel cost escala-
tion, and economic plant lives do not change the basic economic
superiority of the dam scheme over the tunnel scheme.
8-25
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-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:
-It offers the potential for enhancing anadromous fish populations
downstream of the re-regulation dam due to the more uniform flow
distribution that will be achieved in this reach.
It inundates 13 miles less of resident fisheries habitat in river
and major tributaries.
-It has a lower impact on wildlife habitat due to the smaller in-
undation of habitat by the re-regulation dam.
-It has a lower potential for inundating a1~cheological sites due
to the smaller reservoir involved.
-It would preserve much of the characteristics of the Devil Canyon
gorge which is considered to be an aesthetic and recreational re-
source.
Social Comparison
Table 8.19 summarizes the evaluation in terms of the social criter-
ia of the two schemes. In terms of impact on state and local eco-
nomics and risks due to seismic exposure, the two schemes are rated
equally. 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 energy contri-
bution criteria. The results show that the dam scheme has a greater
potential for energy production and develops a larger portion of
the basin's potential. The dam scheme is therefore judged to be
superior from the energy contribution standpoint.
Overall Comparison
The overall evaluation of the two schemes is summarized on 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
evaluation of the Watana-Devil Canyon (El.3) and the High Devil
Canyon-Vee (E2.3) development plans.
8-26
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,-
I
-Economic Comparison
In terms of the economic criteria (see Tables 8.16 and 8.17) the
Watana-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-Devil Canyon scheme would
create more potential environmental impacts in the Watana 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
avera 11.
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 would 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 habitat appears to be decreas-
ing. Habitat manipulation measures could be implemented in this
area to improve the moose habitat. Nevertheless, it is considered
that the upstream moose habitat losses associated with the High
Devil Canyon-Vee scheme, would probably be greater than the Watana
Creek losses associated with the Watana-Devil 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 res·ervoir.
8-27
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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, between Devil Canyon and the Oshetna
River, 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 river
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 archeological 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 greater potential for directly or 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 and the.-creation of a reservoir in
the more no~theasterly section of the basin. This plan would,
thus, create inherent access to more wilderness than waul d the
Watana-Devil Canyon scheme. As it is easier to extend access than
to limit it, inherent access requirements are considered detrimen-
tal and the Watana-Devil Canyon scheme is judged to be more accep-
table 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 acceptable than the High Devil 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 is a question being addressed as
part of ongoin~ studies.
Energy Comparison
The evaluation of the two plans in terms of energy contribution
criteria is summarized 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's potential.
8-28
-
-
....
Social Comparison
Table 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 Ca.nyon 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 plan is therefore selected 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 Susii:na Basin Development Plan
This section 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 comprehensive and detailed alternative
generating scenarios but merely to obtain a preliminary assessment of the feasi-
bility of the Susitna plan in terms of economic, environmental, and social cri-
teria.
~ The main alternative generating scenario considered is the all thermal option
and a detailed evaluation of the 11 With Susitna11 and the all thermal generation
scenarios is carried out. In addition to this, a less detailed as-;essment of
the generating scenarios incorporating non-Susitna Basin hydro development is
also conducted. The objective of the latter evaluation is to assess the econom-
ics of developing alternative and generally smaller hydro projects. fl 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 Susitna11 Generation Scenarios
The development 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 A 11 Therma 1 and
"With Susitna" Generation Scenarios
(i) Economic Comparison
In terms of economic criteria 9 the 11 With Susitna11 scenario is $2280
less costly than the ail thermal option. In order to explore the sen-
sitivity of this comparison in more detail 9 several additional runs
were carried out with the OGP5 model. For these runs~ parameters such
as projected load growth, interest rates 9 fuel costs 9 and fuel escala-
tion rates 9 economic lives and capital costs were varied and the im-
pact 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 11 With Susitna" scenario decreases with
decreasing load growth but still amounts to $1280 million for the very
low forecast. A lower limit thermal plant capital cost estimate was
also considered. The cost estimate was based on the minimum Alaska
cost factor adjustment reported in the literature rather than the
average factor used for the standard cost estimates which appear in
Table 6.4. Even though this results in a 72 percent reduction in the
thermal capital cost, the "with Susitna" scenario is still $1850
million more economic. 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 11 With Susitna" generating scenario costs are still less
than the all thermal scenario by $1320 million.
As shown in Table 8.26 9 shortening the period of economic analysis
from 60 to 30 years (i.e. to 1980-2010) reduces the net benefit to
$960 million. The interest rate sensitivity run results indicate that
the "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 ts $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 million.
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 however9 unl·ikely that such high rates would ever
materialize. Although the net economic advantage of the 11 With
Susitna11 scenario is significantly reduced~ a zero fuel cost escala-
tion rate still results in a more expensive all-thermal generation
scenario.
8-30
(ii) Social Comparison
The evaluation in terms of social criteria is summarized in TablE
8.27. The 11 With Susitna 11 scenario provides greater potential for
non-renewable resource conservation and is, therefore, regarded c.s
superior from this point of view.
There is insufficient information available at this time to full~,
evaluate the impact on the state and local economics. The oattet·n of
power investment expenditures wi 11 probably tend to be more regular
with the all-thermal plan and hence there is potentially a more ~rad
ual impact than with the Susitna-inclusive generation plan. The
timing of the Susitna type investment is probably more disruptiv: ~n
relation to ather large scale Alaskan projects. However, this could
result in countercyclical investment that would tend to reduce such
disruptions.
(iii) Environmental Comparison
( iv)
Table 8.28 broadly summarizes the environmental impacts associ a! ed
with the two scenarios. As indicated, both hydro and thermal dt~vel
opment have potentia 1 for environmenta 1 impact. However, the e:~tent
to which the potentia 1 impacts are realized is very site speci f c.
As specific information on potential future coal-fired generati 19
sources is not available at this time, the overall comparison i;
generic rather than site specific.
Overall Comparison
An overall evaluation is summarized in Table 8.29. This ~ndica1 es
that the 11 With Susitna 11 scenario is clearly superior with regaro to
the econortic 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 in:or-
porating the Watana-Oevil Canyon plan is superior to the all the ·mal
scenario.
(c) Comparison of the 11 With Susitna" and
A 1 ternat i ve HJ'dro Generating Scenarios
Comparison of the 11 With-Susitna 11 and alternative hydro Railbelt generation
scenarios have been made only on the basis of economics. Although prelimi-
nary scre.ening of the alternative hydroelectric developments is made as
described in Section 6~ the absence of immediat~ site-specific data pre·
vents a more detailed assessment of non-economic aspects.
The 11 With-Susitna 11 scenario is generally $1190 million more economic th,:n
the scenario incorporating the alternative hydro developments. Althougl,
development of the Susitna Basin is more economic than developing alterra-
tive hydro, this does not imply that alternative hydro should be neglected.
In fact, as several of the combination runs involving both Susitna and ron-
Susitna hydro alternatives indicate, it may be economically advantageous to
consider development of several alternative hydro sites in conjunction with
Susitna.
8-31
I
I
CXl • w
N
l 1
TABLE 0.1 -POTENTIAL HYDROELECTRIC DEVElOPMENT
Site
Gold Creek2
Olson
(Susitna I I)
DeviL Canyon
High Devil Canyon
( Susitna I)
Devil Creek 2
Watana
Susi tna II l
Vue
Maclaren 2
Denali
Butte Creek2
Notes:
Dam
Proposed
Type
Fill
Concrete
Concrete
fill
Fill
fill
r i 11
Fill
Fill
fill
fill
fill
Height
H.
1911
160
675
855
Approx
650
680
670
610
185
2~0
ApprOil
150
Approx
60
Upstream
Regulation
Yes
Yes
Nn
Yes
No
No
No
No
No
No
No
No
No
Capital
Cost
$ million
9f)0
600
830
1,000
1,500
1,860
1 '390
1,060
5304
Installed
Capacity
(MW)
26fi
200
250
600
000
BOO
350
4110
55
60
40
6
(1)Includes AFDC, Insurance, Amortization, and Operation & Maintenance Costs.
( 2)No detailed engineering or energy studies undertaken as part of this study.
Average
Annual
Energy
Gwh
1' 140
915
1,420
2,980
3, 540
3,250
1,580
1,3711
180
245
22 ~
Economic 1
Cost of
Energy
$/1000 kWh
37
31
27
17
21
28
41
37
124
81
Source
of
Data
USBR 1953
USBR 1953
KAISER 1974
CO£ 1975
This Study
II.
It
II
II
"
"
"
"
USBR 1953
USBR 1953
O)These are approximate estimates and serve only to represent the potential of these two dam sites in perspective.
(4)Inc lude estimated costs of power generation facility.
l ---1
co
l w w
1 1
DAM
Site Type
Gold Creek fill
Olson
(Susitna I I) Concrete
Devil Canyon fill
Concrete
Arch
Concrete
Gt·avity
High Devil Canyon fill
(Susitna I)
Devil Ct·eek fill
Watana fill
Susitna II[ fill
Vee fill
Mac l at· en fit l
Denali fill
Notes:
(1) Dependable Capacity
] 1
TABLE 8.2 -COST COMPARISONS
A t R t
InsEalted
Capacity -MW
600
BOO
BOO
350
400
55
60
s Capital
1980
Capital Cost
$ mill ion
1,000
1.sno
1,86()
1,390
1,060
530
480
Cost Estimate2
·---
Installed
Capacity -MW
2601
1901
776
776
700
792
445
None
(1980 $)
OTR[RS
Cap1taf Cost
$ milJ ion
890
550
630
910
1,480
1,630
770
500
(2) b.cltlding Anchorage/fairbanks transmission intertie, but including local access and transmission.
Source and
Date of Data
USRB 1968( ) -
CO£ 1975( _)
ro£ 1975( ) -
COE 1978( ) -
CO£ 1975( ) -
COl 1978(_)
KAISER 1974(_)
COE 1975(_)
em:. 1975( )
TABLE 8.3 -DAM CREST AND FULL SUPPLY LEVELS
Staged Full tlam Average Dam
Dam Supply Crest Tailwater Height 1
Site Construction Level -Ft. Level -H. Level -ft. fL
Gold Creek No 870 880 680 290
Olson No 1,020 1,030 810 310
Portage Creek No 1 '020 1. 031l 870 250
F"" Devil Canyon-
intermediate
height No 1,250 1,270 8911 465
.... Devil Canyon -
full height No 1,450 1, 4 711 890 675
High Devil Canyon No 1,610 1,63n 1,030 71 f)
No 1,750 1, 775 1,030 855
Wet ana Yes 2,000 2,060 ! ,465 681)
Stage 2 2,200 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
co
I
w c.n
l
~vii Canyon
1470 ft Crest
Item 600 MW
1) Lands, Damages & Reservoirs 26
2) Diversion Works 50
3) Main Dam 166
4) Auxiliary Dam 0
5) Paver System 195
6} Spillway System 130
7) Roads and Bridges 45
8} Transmission line
9) Camp facilities and ~Jpport
10) Miscellaneous 1
11) Mobilization and Preparation
Subtotal
Contingency (20%)
Engineering and Owner's
Administration (12%)
TOTAL
Notes:
10
97
8
30
757
152
91
1000
1
TABLE 8.4-CAPITAL COST £STJMAT£ SUMMARlES
' SUSHi'.JA BASIN DAM SD-IHt:S
COST IN $MilLION 1980
High Devil Canyon
1775 ft Crest
BOO MW
11
48
432
n
232
141
68
10
140
8
47
1137
227
136
1500
Watana
2225 ft Crest
BOO MW
46
71
536
0
244
165
96
26
160
8
57
1409
282
169
1860
Susitna I II
2360 ft Crest
330 MW
13
88
398
0
140
121
70
40
130
8
45
1053
211
126
1390
(1) Includes recreational facilities, buildings and gro•mds and pet·manent operating equipment.
Vee
2350 ft Crest
400 MW
22
37
183
40
175
74
80
49
100
8
35
803
161
96
1060
1
Maclaren
2405 ft Crest
No powet·
25
118
106
.o
0
5
0
57
!l
53
15
379
76
45
son
Denali
2250 ft Crest
No power
38
112
10[)
0
0
0
14
0
50
5
14
333
67
40
440
1
TABLE B.5 -RESULTS Of SCREENING MODEL
Total Demand O~timal Solution first Subo~tima l Solution Second Suboptimal Soultion
Max. [nst. Iota} Max. Ins£. loEal Max. Ins£. Iota[
Cap. Energy Site Water Cap. Cost Site Watet• Cap. Cost Site Water Cap. Cost
Run MW GWh Names Level MW $million Names Level M~l $million Names Level MW $ million
400 1750 High 1560 400 885 Devil 1450 400 970 Watana 1950 400 980
Devil Canyon
Canyon
2 BOO 3500 High 1750 BOO 1500 Watana 1900 450 1130 Watana 2200 BOO 1860
Devil
Canyon
Devil
Canyon 1250 350 710
TOTAL 800 1840
OJ
I J 1200 5250 Watana 2110 700 1690 High 1750 800 15110 High 1750 62fl 1500 w en Devjl Devil
Canyon Canyon
Devil 1350 500 800 Vee 2350 400 1060 Susitna 2300 360 1260
Canyon [{[
TOTAL 1200 2490 TOTAL 1200 2560 TOTAL 1200 2760
4 14[)0 6150 Watana. 2150 740 ~no
N 0 5 0 I. U T I 0 N N 0 5 0 L U T I 0 N
Devil 1450 660 1000
Canyon
TABLE 8.6 -INFORMATION ON THE DEVIL CANYON DAM AND TUNNH SCHEMES
Dev1 ( Canyon lunnei Scheme
Item Dam
Re~ervoir Area
{Acres) 7,5110 320 n 1, 9rln 11
River Miles
Flooded 31.6 z.rJ f1 15.8 ,
"""
Tunnel Length
(Miles) 0 27 29 13.5 29
Tunnel V~lume
( 1 fJOIJ Yd ) 0 11,976 12,863 3, 732 5,1 31
Compensating Flow
Release from
sno 1 Watana (cfs) 1,nnn 1, non 1, OIJO
Dilwnstream2
Reservoir Volume
(1fJfJO Acre-feet) 1' 1110 9.5 3511
Downstream Da~
Height (feet) 625 75 245
Typical Daily
Range of Discharge
From Devil Canyon 6,noo 4,11011 4,f)OO 8,3flr) 1,9011
Powerhouse to to to to to -(cfs) 13,nl1n 14,000 14' rmn B, 9110 4,211n I
I Approximate
Maximum Daily -Fluctuations in
Downstream
Reservoir (feet) 2 15 4
~ Notes:
1 1 'non cfs compensating flow release from the re-rr~gulation dam. 2 Downstream from Watana. 3 Estimated, above existing rock elevation. -
....
-
8-37
co • w co
··~ .... J 1
TABLE 8. 7 -DEVIl CANYON TUNNEL SCHEMES
COSTS, POWER OUTPUT AND AVERAGE ANNUAL ENERGY
Stage
STAGE 1: --
Watana Dam
STAGE 2:
T unne 1:
-Scheme 1
-Scheme 2
-Scheme 32
-Scheme 4
Notes:
Installed
Capaci~ (MW)
-watanavil ~anyon
BOO
BOO
70
850
BOO
Tunnel
550
1,150
330
365
Increase 1 in
Installed Capacity
(MW)
550
42(]
380
365
Devil Canyon
Average Annual
Energy
(Gwh)
2,050
4, 750
2,240
2,49()
(1) Increase over single Watana, 800 MW development 3250 Gwh/yr
(2) Includes power and energy produced at rc-regulation dam
(3) Energy cost is based on an economic analysis (i.e. using 3 pe1·cent interest rate)
I 1 . ncrease 1n
Average
Annual Energy
(Gwh)
2,osn
1, 900
2,180
890
Tunnel Scheme
Total Project
Costs
$ Million
1980
2320
1220
149n
3 Cost of
Addi t ioni l ·
Enet·gy
(mills/kWh)
42.6
52.9
24.9
73.6
-1
-
-
TABLE B.B -CAPITAL COST ESTIMATE SUMMARIES
TUNNEL SCHEMES
COSTS lN $MILLION 1980
Item
land and damages, reservoir clearing
Diversion works
Re-requlation 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 Owner's Administration
TOTAL PROJECT COST
8-39
557
123
fwo 31] ft
dia tunnels
14
35
102
680
21
42
42
15
131
B
47
1 '137
227
136
1,500
453
123
One 41l ft
dia tunnel
14
35
102
576
21
42
42
15
117
B
47
1 '015
203
122
1,340
l 1 -] l
TABLE 8.9. SUSITNA DEV[LOPMENT PLANS
Cumulative
Stage/Incremental Data System Data
Annual
Maximum Energy
Capital Cost Earliest Reservoir Seasonal Product ion Plant
$ Mi 11 ions On-I ine Full Supply Draw-Firm Avg. Fador
Plan Stage Const l'uct ion (1980 values) Date 1 Level ft. down-ft GWH GWH. "' . -"'
1 • 1 1 Watana 2225 ft BOfliW 1860 1993 2200 150 2670 3250 46
2 Devil Canyon 1470 ft
600 MW 1000 1996 1450 1fl'l 5500 62JO 51
TOT Ill SYSTFM 1400 MW 2860
00
I
-t=>
0 1. 2 Wat ana 2060 ft 400 MW 1570 1992 20()[) 100 1710 2110 60
2 Watana l'aise to
2225 ft "360 1995 22fl0 151) 2670 2990 85
3 Watana add 400 MW
capacity 1 "3[)2 1995 2200 150 2670 3250 46
4 Devil Canyon 1470 ft
600 MW 1000 1996 1450 100 5501) 623() 51
TJT AL SYSTf.M 1400 MW 306fJ
1.3 1 Watana 2225 ft 400 MW 1740 199~ 2200 150 2670 2990 85
2 Watana add 400 MW
capacity 150 199"3 2201) 150 26 7!} .3250 46
"3 Devil Canyon 1470 ft
600 MW 1000 1996 1450 100 551lfl 6230 51
TOTAL SYSTE.M1400MW 2i]9'0
]
J l
TABLE 8.9 (Cont~uJed)
Cumulative
Stage/Incremental Data System Data
Annual
Maximum Energy
Capital Cost Earliest Reservoir Seasonal Production Plant
$ Mill ions On-line full Supply Draw-Firm Avg. factor
Plan Stage Construct ion (1980 values) 1 Level -ft. GWH GWH "' Date down-ft. "'
2.1 1 High Devi 1 Canyon
1775 ft BOO MW 150(} 1994 3 1750 150 2460 3400 49
2 Vee 2}5fl Ft 400 MW 1060 1997 2330 151) 3870 4910 47
TOTAL SYSTEM 1200 MW 256i'i
2.2 High Devil Canyon
(XI · 1630 ft 4f10 MW 1140
3
I 1993 1610 100 1770 2020 58
.p. 2 High Devil Canyon
--' add 4fl0 MW Capacity
raise dam to 1775 ft son 19% 1750 150 2460 "'4f10 49
3 Vee 2350 ft 400 MW 1060 1997 2330 150 3870 4910 47
TOTAL SYSTEM 1200 MW 2700
2.3 High Devil Canyon
1 775 ft 4fl0 MW 1390 1994
3 1750 150 2400 276(} 79
2 High Devil Canyon
add 400 Ml'l capacity 140 1994 1750 150 2460 ;400 49
) Vee 2350 ft 4f10 MW 1060 1997 2330 150. 3870 4910 47
TOTAL SYSTt:M 12011 MW 259ij
3.1 Watana 2225 ft BllO MW 1860 1993 2200 15 (} 2670 3250 46
2 Watana add 50 MW
tun110 t 3 30 MW 1500 1995 1475 4 4890 5430 5)
TOTAl SYSTEM 1180 MW 336ri
l J I )
TABU. 8.9 (Continued)
Cumulative
Stage/Incremental Data System Data
Annua I
MaJo.imum Energy
Capital Cost far liest Reservoil' SHasonal Product ion Plant
$ Mil iions On-line Full Supply Draw-firm Avg. Factor
Plan Stage Construction (1980 values) 1 "' Date level -ft. duwn-ft. GWH GWH "'
3.2 Watana 2225 ft 400 MW 1740 199:3 2200 150 2670 2990 B5
2 Watana add 400 MW
capacity 1511 1994 22fJO 150 2670 3250 46
3 Tunnel 33[} MW add
50 MW to Watana 1500 1995 1475 4 48.90 5430 53
3390
CX> 4.1 Watana
I 3 .p. 2225 ft 4()0 MW 1740 1995 2200 150 2670 2990 85 N
2 Watana add 400 HW
capar.ity 150 1996 2200 150 2670 3250 46
3 High Devil Canyon
1470 ft 400 MW 860 1998 145() 100 4520 5280 50
4 Portage Cr·eek
1030 ft 150 MW 650 2000 1f)2f} 50 5110 6()00 51
TOTAL SYSTEM nso MW 3400
NOTES:
(1) Allowing for a 3 year overlap const1·uctlon period between major dams.
(2) Plan 1.2 Stagn 3 is less expP.nsive than Plan 1.3 Stage 2 due to loweL' rrobilization costs.
(3) Assumes rERC license can bn filed by June 1984, ie. 2 years latFJr than for the Watana/Devil Canyon Plan 1.
-
TABLE 8.10-ENERGY SIMULATION SENSITIVITY
-
Resenoir Maximum
Installed Full Supply Reservoir Annual Ener~n:-Gwh Plant -Capacity level Drawdown Factor
Development MW Feet Feet Firm (~D) Average (%) ... 10
"""
Watana 2225 Feet 800 2200 100 2510 (89) 3210 ( 101) 45.8
F 800 2200 150 2670 (94) 3250 ( 103) 46.4
800 2200 175 2770 (98) 3200 (101) 45.7
-800 2200 Unlimited 2830 (100) 3170 ( 1 00) 45.2
Notes: -
( 1) Second lowest energy generated during simulation period.
-
-
8-43
] l j l J
TABLE 8.11. SUSITNA ENVIRONMENTAL OEV£LOPM£NT PlANS
umu a 1ve
Stage/[ncremental Data System Data
Annuat
Mal<.imum Energy
Capita I Cost [ar1iast Reservoir Seasonal Product ion Plant
$ Mi 1 Jions On-line full Supply Draw-firm Avg. Factor
...f..!!in Stage Construction (1980 vaiues) Date 1 Leve 1 -ft. dmm-ft GWH GWH. %
[1.1 1 Watana 2225 ft 801J.1W
and Re-Regulation
Dam 1960 1993 2200 150 2670 3250 46
2 Devil Canyon 1470 ft
400MW 900 1996 1450 100 55211 6071] 58
TOTAL SYSTD~ 120()tW 1B6lT
co £1.2 1 Watana 2n60 ft 400MW 1570 1992 2000 100 1710 2110 60
I 2 Watana raise to ~
~ 2225 ft 36fl 1995 2200 150 2670 299[) 85
3 Watana add 40fl.tW
capacity and
? Re -Regu 1 ation Dam 23:'J 1995 2200 150 2670 5250 46
4 Devil Canyon 1470 ft
401lMW 900 1996 1450 100 5520 6071) 58
TOTAL SYSTEM 121l£l.1W JObiJ
E1.3 1 Walana 2225 ft 40fl<IW 1740 1993 22fl0 15(1 26 71) 29911 85
2 Watana add 400MW
capacity and
Re-Regulation Dam 25fl 199.5 Z2fl0 150 26 70 3250 46
3 Devil Canyon 1470 ft
400 MW 900 1996 1450 '100 5520 607fJ 58
TOTAl SYSTEM 120!l1W 1m
]
TABLE 8.11 (Continued)
Cumu I at i ve
Stage/Incremental Data S~stem Data
Annual
Ma>~imum Energy
Capital Cost Earliest Reservoir Seasonal Production Plant
$ Mi.llions Ckl-line Full Supply Draw-firm Avg. factm·
Plan Stage Construction (1980 values) Date 1 Level -ft. down-ft. GWH GWH 0' .a
[1.4 1 Wa tana 2225 ft 401l-tW 1740 1993 2200 150 2670 2990 85
2 Devil Canyon 1470 ft
40£J.1W 900 199t 1450 100 5190 567() 81
TOTAL SYSTEM 80fl.1W 2640
E2.1 1 High Devil Canyon
1775 ft 801l-tW and
()) Rc-Regulation Dam 1600 1994 3 1750 150 2460 3400 49 I .p. 2 Vee 2_;sort 40fl.tW 1060 1997 2330 150 3870 4910 47
Ul TOTAL 51ST£M 1200MW 2660
E2.2 1 High Devil Canyon
1630 ft 40fl.1W 1140 199}3 1610 100 1771) 2020 58
2 High Devil Canyon
raise dam to 1775 ft
add 401l-tW and
Re-Regu 1 ation Dam 60r] 1996 1750 150 2460 3401) 49
3 Vee 2JSO ft 400 NW 1060 1997 2330 150 3870 4910 47
TOTAL SYSTE:M 120fl.tW 2'Bnfj
E2.3 1 High Dev i 1 Canyon
1 77 5 ft 40fl-1W 1390 1994 3 1750 150 2400 2760 79
2 High Devil Canyon
add 40nMW capa~ity
and Re-Regul ation
Dam 240 1995 1750 150 2460 3400 49
3 Vee 2350 ft 400MW 1060 1997 2330 150 3870 4910 47
TOTAL SYST[M 1200 269n
1 J 1 -1 -. J I -.. J ) -. 1
TABlE 8.1 i (Continued)
Cumutative
Stage/Incremental Data S~stem Data
Mnual
Ma;..imum Energy
Capital Cost Earliest Reservoir Seasonal Production Plant
$ Hi I lions On-line full Supply Draw-firm Avg. Facto1·
Plan Stage Construction ( 1980 values) 1
Date level -ft. down-ft. GWH GWH IV
"'
£2.4 High Devil Canyon
1755 ft 401J.tW 1390 19943 17511 150 2400 2760 79
2 High Devil Canyon
add 400HW capacity
and PortagP..Creek
Dam 150 ft 790 1995 1750 150 3170 4080 49
} Vee 2J50 ft
400MW 1060 1997 2330 150 4430 5540 47
TOTAl SYSTEM 'miTT
CP 0.2 1 Watana
I 2225 ft 40!l-1W 1740 1993 2200 150 2670 2990 65 ~
"' 2 Watana add
400 MW capacity
andRe-Regulation
Dam 250 1994 2201) 150 26711 "5250 46
3 Watana add 5rHW
Tunnel Scheme 3311-1W 1500 1995 1475 4 4890 5430 53
TOTAl SYSTEM 1180MW mrr
[4 .1 1 Watana
2225 ft 401J.1W 1740 1995 3 2200 150 2670 2990 85
2 Watana
add 400MW capacity
and Re-Regulation
Dam 25fl 1996 2200 150 2670 3250 46
3 High Devil Canyon
14 70 ft 400MW 860 1998 1451) 100 4520 5280 50
4 Portage Cteel<
1030 ft 150MW 650 2000 1020 50 5110 600fl 51
TOTAl SYSTEM 1350 MW J51m
NOTES:
rn-AJ lowing fm· a 3 year over I ap construct ion petiod between major dams.
(2) Plan 1.2 Stage J is less e;..pensive than Plan 1. 3 Stage 2 due to lower 100bi lization C"osts.
0) Assumes f£RC license can be filed by June 1984, ie. 2 years later than for the Watana/Devi! [anyon Plan 1.
TABLE 8.12 -ANNUAL fiXED CARRYING CHARGES
Economic Parameters
Total -Economic Cost of Annual
Life Money Amortization Insurance Fixed Cost
Project Type -Years .. ., "' Ql
"' ,. •0 ,.
, ..... Thermal -Gas Turbine
(Oil Fired) 20 3.00 3. 72 0.25 6.97
-Diesel, Gas Turbine
(Gas Fired) and
Large Steam
I'""' Turbine 30 3.00 2.10 n.zs 5.35
-Small Steam Turbine 35 3.00 1.65 0.25 4. 91)
Hydropower 50 3.00 0.89 0.10 3.99
-
-
-8-47
l
Smntna Development Plan Inc.
On line Dates
Plan Stages
No. 1 2 } 4
£1.1
£1.2
£1.3
£1.4
Modified
1993 2000
1992 1995 1997 2002
1993 1996 2000
1993 1996
1998 20a1 2005
1993 2000
[2.1 1994 2000
E2.~1 1993 1996 2000
1993 1996
Modified
[2. ~ 1993 1996 2000
3.1 1993 1996 2000
Special
3.1 1993 1996 2000
£4.1 1995 1996 1998
~:
l
TABLE 8.13-RESULTS Or ErONOMIC ANALYSES or SUSITNA PLANS-MEDIUM LOAD fORECAST
OGP5 Run
[d. No.
LXt::7
L5Y9
LBJ9
L7W7
LA07
LCK5
LB25
L601
L[ll7
LfB3
L6U7
L615
LTZ5
lnstalled Capac1ty (RW) by
Category in 2010
Tnermal Hydro
toai Gas oil Otfier susitna
JOO 426
200 5111
300 426
5flfl 651
400 276
2110 726
400 651
:mn 651
500 651
300 726
200 651
2fl0 651
200 576
0
n
0
0
50
60
20
30
220
30
30
144
144
144
144
144
144
144
144
144
144
144
144
144
1200
1200
1200
800
1200
BOO
BOO
1200
ann
non
1180
1180
1200
lotal System
Installed
Capacity In
2010-MW
2070
2045
2070
2fl95
2050
1920
2fl55
2315
2125
2690
2205
2205
2150
. 1 at a [ Sysfem
Present
Worth Cosi
$ Million
5650
6030
5850
6%0
6070
5890
6620
6370
6720
6210
6530
62m
6050
(1) Adjusted to incorporate cost of re-regulation dam
-1 1 )
Remarks Pertaining to
lhe Susitna Basin
Development Plan
Stage 3, Devil Canyon Dam
not constr•Jcted
Delayed implementation
schedule
Total developrrent U.miteo
to 800 MW
High Devil Canyon limited
to 400 MW
Stage 3, Vee Dam, r.ot
constructed
Vee dam replaced by
Dlakacha;ma dam
Cap it a l cost of tunnel
l'educed by 50 percent
Stage 4 not constructed
I l ) J i 1 1 ] I 1 1
TABlE 8.14-RESULTS OF ECONOMIC ANALYSES Of SUSITNA PLANS-LOW AND HIGH LOAD fORECAST
Susitna Development Plan inc. Installed Capacity (MW) by Total System Total System
Orihne Dates Categor~ in 2010 Installed Present Remarks Pertaining to
Plan Stages OGP.5 Run Thermal H}:dfO Capacity In Worth Cost the Susitna Basin
No. 1 2 :J 4 Id. No. f:oal Gas Oil Other Susitna 2010-MW $_Million Development Plan
VERY LOW f0RECAST1
[1.4 1997 200.5 l787 0 6.51 .50 144 800 164.5 36.50
LOW LOAD fORECAST
£1.3 1993 1996 2000 low energy demand does not
warrant plan capacities
[1.4 1993 2002 LC07 · 0 351 40 144 BOO 133.5 43.50
1993 LBK7 200 .501 80 144 400 1325 4940 Stage 2, Devil Canyon Dam,
not constructed
[2.1 1993 2002 LG09 100 426 30 144 BOO 1500 4560 High Devil Canyon limited
to 400 HW
1993 LBU1 400 .501 0 144 400 144.5 48.50 Stage 2, Vee Dam, not
constructed
(X), E2.3 1993 1996 2000 low energy demand does not
I warrant plan capacities
U1 Special 0 Capital cost of tunnel 3.1 1993 1996 2000 l613 0 .576 20 144 780 1520 4730
reduced by 50 percent
3.2 1993 2002 l609 0 576 20 144 780 1.520 5000 Stage 2, 400 MW addition
to Watana, not con;Jtructed
HIGH LOAD FORECAST
£1.3 1993 1996 2000 LA73 1000 9.51 0 144 1200 3295 10680
Modified zoos2 £1.3 1993 1996 2000 LBV7 BOO 651 60 144 1700 nss 10050 Chakachamna hydroelectric
generating station (480 MW)
brought on line as a fourth
stage
£2.3 1993 1996 2000 LBV3 1300 951 90 144 1200 3665 11720
Modified
:zom2 £2.3 1993 1996 2000 LBY1 1000 876 10 144 1700 3730 11040 Chakachamna hydroelectric
generating station (460 MW)
brought on line as a fourth
stage
~:
• I 1 ' },ncor.~~~.,ting. 1 ""."j man---,..·:mt e~:;~;;,onse1;·· ~~.ton j ... ·"";}. ""'""·A~~ ~d.~cr# ~;·'-~-~~~ i.-~1',:--~ ~-... 5~ ~-. ... ilJI!I!I.'"f li! ..•. Jt L.l ... SI '--····-co.>>', _ ,tA-,.>.1·;•{ ·
(X)
I
U'1 _.
TABLE 8.15-RESULTS OF ECONOMIC SENSITIVIrY ANALYSES rOR GENERATION SCENARIO
INCORPORATING SUSIINA BASIN DEVELOPMENT PLAN E1.3 -MlDIUH fORECAST
Installed Capacity (MW) by
Categorl:: in 2010
Descri(!tion Parameter OGP5 Rm ihermal H;tdro
Parameter Varied Values ld. No. Coal Cas i':hl lither !;usitna
Interest Rate 5~ Lras 300 426 0 144 1200
9l't lf87 300 426 0 144 1200
fuel Cost ($million Btu,
natural gas/coal/oil) 1.60/0.92/3.20 L5H 100 576 20 144 1200
fuel Cost Escalation (%,
natural gas/coal/oil) 0/0/0 L557 0 651 30 11•4 1200
3.98/0/3.58 l)63 JOO 426 0 144 1200
Economic life of Thermal
Plants (year~ natural
gas/coal/oil 45/45/JO L505 45 367 233 144 1200
Thermal Plant Capital
Cost ($/kW, natural gas/
coal/oil) 350/2135/778 l£07 300 426 0 144 1200
Watan~/Devil Canyon Capital
Cost ($million, Watana/
Devil Canyon) 1990/1110 l5G1 300 426 0 144 1200
2976/1350 L075 300 426 0 144 1200
Probabilistic load forecast L8T5 200 1476 140 144 1200
.!:!Q_!E:
(1) Alaskan cost adjustment faclol' reduced from 1.6 to 1.4 (see Section B._)
(2) Excluding AfDC
Total Total
System System
Installed Present
Capacity Worth
In 2010 Cost
MW $ Million
2070 4230
2070 2690
2040 5260
2025 4360
2070 5590
1989 6100
2070 5740
2070 6210
2070 6810
3160 6290
1
Remarks
ZO% fuel cost reduction
Zero escalation
Zero coal cost escalation
Economic lives increased
by 50%
Coal capital cost L'educed
by 22%
Capital cost for DeVl'
Canyon LlEIIl increased by 23%
Capital cost for both dams
increased by 50%
TABLE 6.16-ECONOMIC BACKUP DATA FOR EVALUATION Of PLANS
Iota! Present Vkirth east For 1991 -2!1411
cenerab.on Plan
Period $ Million (% Total)
Generabon Plan Generabon Plan
With High Devil With Watana -With Watana -All Thermal
Parameter Can}:on -Vee Devil Can~ on Dam Tunnel Generation Plans
Capital Investment 2600 (44) 2740 {4 7) 3170 (49) 25:W 01)
Fue 1 3220 (50) 2780 (47) 3021) (46) 52<W (64)
Operation and Maintenance 350 ( 6) 330 ( 6) 340 (5) J70 (5)
TOTAL: 6370 (100) 5850 ( 1110) 6530 {100) 81·30 (1 00)
.....
....
8-52
co
I
0'1 w
l ] j
TABLE 9.17-ECONOMIC EVALUATION Of DEVIl CANYON DAM AND TUNNEL SCHEMES AND WATANA/DEVIL CANYON AND HIGH DEVIL CANYON/VEE PLANS
ECONOMIC EVALUATION:
-Base Case
SENSITIVIlY ANALYSES:
-load Growth
-Capital Cost Estimate
-Period of Economic
Analysis
-Oisco•Jnt Rate
-fuel Cost
-fuel Cost Escalation
-Economic Thermal Plant
Ufe
low
High
Period shortened to
(1980 -2010)
5'!<:
8% (interpolated)
9%
Present worfh of Net Beneht ($ milhon) of total generafion
system costs for the:
Devil Canyon Dam over Watana/Devil Canyon Dams over
the Tunnel Scheme the High Devil Canyon/Vee Dams
680
650
N.A.
Higher uncertainty assoc-
iated with tunnel scheme.
230
520
210
1040
Higher uncertainty associated with
H.D.C./Vee plan.
160
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/Oevil 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 perlod of evaluation
decreases economic differences.
Ranking remains unchanged.
As both the capital and fuel costs associated with the tunnel Ranking remains I.Slchanged.
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.
~ coal escalation
50% extension
0~ extension
] ]
rABLE B. 18 -£NVJROtft£N1AL £VALUAIJON I»' OCVIL CANYON DAH AND lli!N(L SCHEHE
Envlronmental
Attribute
Ecological•
-DowmJtreaa rtsherles
'!"d Wtldllfe
Realdenl fisheries:
Coocernu
Effects resulting
fra. changes in
water quantll y and
·quality.
loaa or residant
flshertea hebttat.
losa or wlldllf~
habitat.
Ajipra•ual
(Differences ln t~ect
or two achemea)
NO algniflcent differ-
ence between sche11111a
regarding effects dDwn-
atrellll of (lev 11 Canyon.
Difference ln react. bet"""" Oev 11 Canyon
de-ood lUMel re-
re!I'Jlalion da11.
Hinlmal differences
between ache~s.
Minimal differences
between echemas.
inoodation of Potential differences
archeological sitec. ~etween sche.a11.
lnundolicn of Devil Slgnificalll dtfferonce
Canyon. between scheaes.
ldent lflcation
of dlrrerence
lflth th11 tunnel B<;heMe con-
trolled flo~ between regula-
tion daM an~ downstream poMer-
house offers potential for
INlodr OIIIOUs ft sher I es enhance-
.ent In thla 11 aile reach of
the river.
llev 11 Canyon d8fll would lnwldate
27 •ilea of the Susitna River
and approxl.ately 2 ailes of
Devil Creek. Jhe tunnel fiChe~~e
I«!Uld io11ndeh 16 Ill lies of the
Suoltna River.
Jhe ~at sensitive wildlife ha-
bitat in thla reach la upstream
of the tunnel re-regulatlon du
.....,re there !a no aignl flcent
difference between the schemes.
lhe Dev ll Canyon dllll scheae In
add it ion in,...dat ea lhll rIver
valley between the two d11111
site~ teaultlng In a aoderate
increase in impacts to
wildlife.
!lu10 lo the larger area inOSI-
dat ed the pr obeb Ill t y of !nun-
del ing archeological sites Is
Increased.
the Devil Canyon is considered
a unlqua reaource, 80 percent
of which would be Inundated by
the Dev IJ Canyon lhlnl ach.,...,.
lnis would result In a loss of
both on aesthetic value plus
the potent iel for ..toile water
reereal ion.
OVERAll EVAl~IION1 fhe tunnel schelliC has overall s lower it•pacl on the envir0fll11811t.
Appruiael Ju?geMenl
ftJt a factor in evaluation of
B<;t-e.
lf flshQrles enhance~~ent oppor-
tunity ~:an be realized the tun-
nel acheaa offers a positive
•lttgatton .eaeure not available
•lth the Devll Canyon d11111
ec'-e. fhlu opporl<Ullty Is
considered MOderate ~.d favors
the tunnel ach-.
lhis reach of rlver is not con-
aldered to be highly ~ignlflcaol
for resident ftsnerlee and thus
the difference bet~en the
IIChe..,s te •lnor and favors the
tuooel &cheiiB.
The difference In toes of wlld-
llfe hahltal Is considered II!Dd-
erate and favors the tunnel
seh-e.
A aignlflcant archeological
site, if identified, can proba-
bly be exceveted. this concern
Ia not considered a foetor In
ln eeh-evaluation.
file aesthet ic and to BOlle e•tent
the recteat lonal losses sssoci-
ated wllh the developR~ent of the
Oev il Canyon daa is the IllS In
aspect favodnq the tunnel scheliiB.
1
SCheiiil JUdged to l•a~e
the leual potential lfi!Pacl
funnel llC
)(
X
)(
CX>
I
U1
U1
.. ···~ 1 1
TABLE 8,19 -SOCIAL EVALUATION Of SUSITNA BASIN DEVELOPMENT SCHEMES/PLANS
Soctal---------------------------~l~un~n~e~l~~oe~v~i~I~t:~an~y~o~n~---nA~ig~h~b~e-vTiTI~c~a~n~y~o~n~/---T,W~aTE~an~a~/~De~vTiTt----------------------------------
Aspect Parameter Scheme Dam Scheme Vee Plan Canyon Plan
Potential
non-renewable
resoarce
displacement
Impact on
state economy
Impact on
local economy
Seismic
exposure
Overall
Evaluation
Million tons
Beluga coal
over sr vears
J
Risk of major
structural
failure
Potential
impact of
failure on
human life.
80 110 170 210
..
All projects would have similar impacts on tho 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. Wat ana/
Devil Canyon plan higher
than High Devil Canyon/
Vee pIan.
Essentially no difference
between plans/schemes.
-
I~
-
TABLE 8.20-ENERGY CONTRIBUTION EVALUATION or THE DEVIL
CANYON DAM AND TUNNEL SCHEMES
Parameter
Total Energy Production
Capab~hty
Annual Average Energy GWH
Firm Annual Energy GWH
% Basin P~tential
Develop.@.
Ener?y Potential Not
Deve oped GWH
~:
Dam
285(}
25911
43
60
Tunnel
2240
2o~n
32
380
Remarks
Devil Canyon dam annually
develops 610 GWH and 540
GWH more average and firm
energy respectively than
the Ttnnel scheme.
Devil Canyon schemes
develops more of the
basin potential.
As current 1 y envi.saged,
the Devil Canyon dam does
not develop 15 ft gross
head between the Watana
site and the Devil Canyon
r-eservsoir. The tunnel
scheme incorporates addi-
tional friction losses in
tunnels. Also the compen-
sation flow released from
re-regulation dam is not
used in conjtnction with
head between re-regulation
dam and Devil Canyon.
( 1} Based on annual average energy. Full potential based on USBR four
dam scheme (Reference _}.
8-56
-
-
TABLE B.21 -OVERALL EVALUATION OF TUNNEL SCHEHE AND DEVIL CANYON DAM SCHEME
ATTRI801£
Economic
Energy
Contribution
Environmental
Social
Overall
Evaluation
sOPER !OR PLAN
Devil Canyon Dam
Devil Canyon Dam
Tunnel
Devil Canyon Dam (Marginal)
Devil Canyon dam scheme is superior
Tradeoffs made:
Economic advantage of dam scheme
is judged to outweicjl the reduced
environmental impact associated
with the tunnel scheme.
8-57
00
I
U1
~
[nvifon•mtal Attribute
Ecol'l'ical: 1J lafiiriea
2) Wildlife
e) Hoose
b) Cari~u
c) f urbearera
d) Bh-da and Bears
)
I ABlE 8. 22 -£NVIRCtH:NJAL [VAI..UAIION Of lfAIANA/OCYil CAN'tOH AND IIIGtl II:VIl CANVON/YE£ OCV£LOPH£Nl PLANS
Pian COI!I(!erlson
No sigolfica •• t difference in effects on downalrea•
anadro1111.1ua fishedss,
liOC/V would inundate epprod11otely '~ •i lea of the
Susitna River and 28 •lies of tr ibutart alrea~~~a, In-
cluding the lyone River.
W/DC would inundate approximately 84 ~ilea of the
Susitna RiYer and 24 •Ilea or trJbular~ streaiiiS,
including lfatana Creek.
Appraisal Judge11111nt
Due to the avoidance of the lyons River,
leaeer inundatiun of resident fisheries
habitat snd no aigoificant dlffer11nce in the
effect11 011 anadi"OIIOUS fitiherles, the W/OC plan
is judged to have Jess llllflBCt.
IWC/V would Inundate t2J •lles of critical winter river Due to the lower potentlel for direct i~act
botto• habitat. on 11100oe POJ>Ulotiona within the Suaitna, the
li/OC plan ie judged auperlor.
lf/DC would inundate 100 ailes of this river bottom
habitat.
IIOC/V would luundate a large area upatrea.-of Vee
uU ihed by three sob-populati011s of 111n0ae that range
in the northeast section of the basin.
lf/OC would inundate the lfat~ta Creek area utilized by
auoae. fhe condition of this sub-population of moose
and the quality of the habitat the)· ar& using appears
to he decreaslllg.
lhe increased length of river flooded, earcially \4)-
sltea• froa the Vee daM site, would resul Jn the
IIDC/V plan creotlng a greater potential dl~islon of
the Nelchina herd'a range. In addition, an increase
in range would be directly inundated by U!e Vee res-
ervoir.
the area flooded b~ the Vee reservoir is C;;Jnaldcred
l"'f)ortant to aOIIIB key furbearero, partlA•tiarly red fo11.
this area is judged to be 1110re t,..mrtonl than the
Watana Creek area that would be im•odated by the W/OC
plan.
forest habitat, lqJortant for birlla and black bears,
edst along the volley slopes. lhe loss of this habi-
tat would be greater ~ith the lf/OC plan.
lhere Ia a high potentlEil for discovery of archeologi-
cal sites in the easterly region of the i.%Jper Sualtna
8asiu, The IIDC/V plan has a greater potential of
affecting these sites. for other reaches of the river
the differer~e between plans is considered minimal.
lire to the potenUal for a greater t..,act m
the Nclchlna caribou herd, the IIOC/V scheme
is considered !nferlor.
D..oe to the lesl!er potential for inpact on fur-·
bearers the 11/0C is judged to be superior.
lhe llOC/V plan is judged superior.
the 11/0C plan is judged lo ha"e a lower po-
tent"-'' .,ffect 011 archeological illtes.
t'lan judged to Fiiive the
least ~olentisl i;7act ROC/ oc
X
X
X
X
X
1
JA8l[ 8.22 (Conlinued)
En'llr01111l8ntal Attribute
Aesthetic/
lsnd Uae
l -]
Plan C2!Parhlon
With either achelll8, the aesthetic quality or both
IE'Ill Cl!llyon and Yea Canyon would be hpa.lred. The
IIDC/Y plan would also lnoodate Jsuaena Falla.
Due to construction at Vee Do• elht and the size or
the Vee Reservoir, the tiOC/Y plan would inherent l)'
create access to .,re wlldemess area thllfl would the
W/DC plan.
Both plan11 lf!Voct the 'Ialley aesthetics. The
differeJ~e is ~onsldered ~lnlMDl.
As lt Is easiw,r to extend access llum to
IJ•lt Jt, Inherent accesa requlr~ts were
cnr,eidel'ed detrllllt!ntal and the W/OC plan Is
.Judged superior. Jhe ecological sensU tv it)'
of the ares opened by the ttOC/Y phn rein-
forces this judgeaent.
OVERAI.l EYAlUAUONa lhe W/OC plan is judged to be superior to the HOC/Y plan.
(lhe lower i_,act on birds and bears associated with IIOC/Y plan la considered to be outweighed b~ ell
the other i!'!Pach which favour the W/OC plan.)
()) ~~
I c.n W = Watana flail
lC) OC : Devll Canyon DB•
IIIJC = High De11ll Canyon De•
Y = Vee D&ll
]
l'loo judgelf (o hove the
least ~ot.enllel i~act ROC! oc--
X
-
-
-
TABLE 8.23 -ENERGY CONTRIBUTION EVALUATION OF THE WATANA/DEVIL CANYON
AND HIGH DEVIL CANYON/V££ PLANS
Parameter
Total Energy Pt<oduction
f!pa61liEx
Annual Average Energy GWH
Firm Annual Energy GWH
% Basin Potential
~veloped (1)
Enerfy Potential Not
![e~e oped GwR (z}
Notes: --
Watanr1/
Devil Canyon
607(1
5520
91
60
A"igh 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 rc-
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 energye Full potential based on USSR four
dam schemes (Reference ).
(Z) Includes losses due to ~~utilized head.
8-60
-
-
-
-
TABLE 8.24 -OVERALL EVALUATION OF THE HIGH DEVIL CANYON/VEE AND
WATANA/DEVIL CANYON DAM PLANS
AIIRlBOI£
Economic
Energy
Contribution
Environrrental
Social
Overall
Evaluation
SOPtR lOR fltAN
Watana/Devil Canyon
Watana/Devil Canyon
Watana/Devil Canyon
Watana/Devil Canyon (Marginal)
Plan with Watana/Devil Canyon is
superior
Tradeoffs made: None
8-61
J
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
Descrietion Parameter OGP5 Run Thermal In 2010 Worth Cost
Parameter Variea Value ld. No. Coal Gas lli1 Hydro Total MW $ Million Remarks
Interest Rate 5~ LEA9 900 800 so 144 1895 5170
9% L£81 900 801 50 144 1895 2610
fuel Cost ($million Btu,
natural gas/coal/oil) 1.60/0.92/3.20 L1K7 BOO 876 711 144 1890 7070 2m.\ fuel cost reduction
fuel Cost Escalation ("',
natural gas/coal/oil) 0/0/0 LS47 0 1701 10 144 1855 4560 Zero escalation
3.98/0/3.58 LS61 1100 726 10 144 1980 6920 Zero coal cost escalation
EconoiRic Life of Thermal
(X) Plants (year~ natut·al
I gas/coal/oil 45/45/30 L5B3 1145 667 51 144 2n07 7850 Economic life increased
0'\ 50%
N
Thermal Plant Capital
Cost ($/kW, natural gas/ 350/2135/778 LAL9 1100 726 10 144 1980 7590 Coal capital cost reduced
coal/oil) by 22%
co
I
0\ w
I -. l ]
TABLE 8.26 -ECONOMIC SE:NSITIVIT.Y Of COMPARISON Of GENERATION PLAN WITH
WATANA/D£VIl CANYON AND THE ALL THERMAL PLAN
Present worth of Net Benefit ($million) of total generation
system costs for the Watana/Oevil Canyon plan over the all thermal plan.
~P'-a~ra~m~e~t=e~rs~--------------~se--=n=s~lt~l~V~l~ty~-A~n~a~t~y~s=es=---~P'-r=e=se~n~t~w=o=rt~h~(M$~m~iT}Tllr.o~n~)r------------------~~ie_m_a_r~ks------------------------------
LOAD GROWTH Very low
low
Medium
Hicj)
CAPITAL COST ESTIMATE low Thermal Cost2
High 3Hydroelectric
Cost
PERIOD OF ECONOMIC ANALYSIS 1980-2040
1980 -2010
DISCOUNT RATE
fUEL COST
fUEL COST ESCALATIONS
ECONOMIC THERMAL PLANT
LIFE
Notes:
3~
5%
8~ (interpolated)
9~
fl\: escalation for all
fuels
0% escalation for
coal only
50% extension to all
thermal plant life
1280
1570
2280
2840
1850
1320
2280
960
2280
940
0
-80
1810
200
1330
1800
(1) All parameters, except load growth, tested using .oodium load forecast.
( 2) Thermal capital cost decreased by 22~.
(3) Estimated Susitna cost increased by 5rn.l.
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 1ncertainty does not effect economic
ranking.
Shorter period of evaluation decreases economic dif-
ferences. Ranking remains •mchanged.
Below disco1nt rate of 8~ the Watana/Devil Can~on
plaol is economically superior.
Watana/Devil Canyon plan remains economically super-
ior for wide range of fuel prices and escalation
rates.
Economic benefit for Watana/Oevil Canyon plan rela-
tively insensitive to extended thermal plan economic
life.
(4) All fuel costs reduced by 20%. Base case costs $/million Btu: Coal 1.15, Gas 2.00, Oil 4.00
(5) Base ca:3e escalation: Coal 2.93%, Gas 3.98%, Oil 3.58%.
co
I m .r;:..
-]
Socia) Aspect
Potential non-renewable
resource displacement
Impact on state economy
Impact on local economy
Seismic exposure
Overall
Com.e_arison
1 l ]
TABlE 8.27 -SOCIAL COMPARISON OF SYSTEM GENERATION PLAN WITH
WATANA/OEVIL CANYON ANO THE All THERMAL PLAN
Parameter
Hi Ilion tons of
Beluga coal, over
50 years
Direct 4 Indirect
employment and in-
come.
&Jsiness investment.
Risk of majm· .
structural failure
Potentia 1 impact of
failure on human
life.
All iherma[
Generation Plan
Gradually, contin-
uous 1 y growing
impact.
Generat1on ~Ian w1th
Watana/Oevil Canyon
210
Pbtentially more dis-
t'upt i ve 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
ovel·all assessment of plans.
l
Remarks
With Watana/Oevil
Canyon plan is
superior.
Available information
insufficient to draw
definite conclusions.
Both scenarios judged
to be equa 1.
-
....
-
-
TABLE 8.28 -GENERIC COMPARISON Of ENVIRONMENTAL IMPACTS OF A SUSITNA
BASIN HYDRO DEVELOPMENT VERSUS COAL FIRED THERMAL
GENERATION IN THE BELUGA COAL FIELDS
tiiVironmental
Attributes
Ecological:
Cultural:
Aesthetic/
Land Use:
Concerns
Susitna Bas1n Develoement
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.
8-65
Thermal Generation
Potential for impact on
fisheries resulting from
water qual.it y 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 destruction 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 GENERATlON PLANS
WITH THE GENERATION PLAN INCORPORATING WATANA/DEVIL
CANYON DAMS
An!H60it SuPrR toR I'( AN -
Economic With Watana/Devil Canyon
Environmental Unable to distinguish difference in
this study due to site specific
nature of impacts
Social No significant overall difference
Overall Plan with Watana/Devi L Canyon is
judged to be superior
Evaluation Tradeoffs made: Not fully explored
8-66
: }
I .-.....
··.J
] l
PREVIOUS
STUDIES AND
FIELD
RECONNAISSANCE
12DAM
SITES
GOLD t;REEK
DEVIL CAN'VON
HIGH DEVIL CAN'I'ON
DEVIL CREEK
WATANA
SUSITNA ill
VEE
MACLAREN
DENALI
BUTTE CREEK
TYONE
l
SCREEN
ENGINEERING
LAYOUT AND
COST STUDIES
7DAM
SITES
COMPUTER MODELS
TO DETERMINE
LEAST COST DAM
COMBINATIONS
3BASIC
DEVELOPe
MENT
PLANS
CRITERIA DEVIL CANYON OBJECTIVE WATANA I DEVIL
ECONOMICS HIGH DEVIL ECONOMIC CANYON
ENVIRONMENTAL CANYON HIGH DEVIL
ALTERNATIVE WATANA CANYON/ VEE
SITES SUSITNA liT HIGH DEVIL
ENERGY VEE CANYON I WATANA
CONTRIBUTION MACLAREN
DENALI ADDITIONAL SITES
PORTAGE CREEK
1
DATA ON DIFFERENT
THERMAL GENERATING
SOURCE;.;;;S ____ --&. _ _,
CRITERIA
ECONOMIC
COMPUTER MODELS
TO EVALUATE
-POWER AND
ENERGY YIELDS
-SYSTEMWIDE
ECONOMICS
WATANA I DEVIL
CANYON
ENVIRONMENTAL PLUS THERMAL
SOCIAL
ENERGY
CONTRIBUTION
LEGEND
DIS HIGI-l DEVIL CANYON ~STEP NUMBER IN
DIS WATANA STANDARD PROCESS
(APPENDIX A)
SUSITNA BASIN PLAN FORMULATION AND SELECTION PROCESS
FIGURE 8.1
PORTAGE CR.
-I
100
I
l
~~ . ~, > 0:: (I) iiJ
u dl a
9 lj g 870' .. ,_
-H
C( z ...
~
(I)
z
~ z
"' u
...J s:
ILl a
X
~
X
a:
0
!l > w
0 1750'
r-1450'
~
1020
120 140 160
RIVER MILES_...,.
1
"' 1905'-z
;! 20501 3l 2200' •
1000'
500'
180
1
OSHETNA RIVER
.,........---, 1 -TYONE RIVER
r-1----·-L.J 20001
::::::rr-MACLAREN RIVER
~-~----S-.1 2 2200 1
ooo'
Fl I z I fj
I I w
C( ~ I ~ 1&1 _) z I I ... ...J I ... !::: u z 3
I I C( iiJ ::l
(I) LaJ 0 2535'~ ::l iiJ
: 2350'1 Ji2395,\ II) > .5 2 500' --Lz3oo' 2 -ooo'
I 500'
200 220 240 260 280
PROFiLE THROUGH ALTERNATIVE SITES
FIGURE 8. 2 IIIII
j 1
GOLD
CREEK
LEGEND
OLSON
COMPATIBLE ALTERNATIVES
D
1
DEVIL
CANT'O'N
MUTUALLY EXCLUSIVE ALTERNATIVES
HIGH
DEVIL
CANYON
WATANA
DEVIL
CREEK
SUSITNA m
WATANA SUSITNAm VEE MACLAREN DENALI
T
VEE
< · .. ··.· . t i~?!?
\ > \ .·.. {49~l
MACLAREN t .. ·
DENALI i .
BUTTE
CREEK TYONE
~------r------------------L~·~~·-~.~-~,~c·.~--------
BUTIE CREEK
DAM IN COLUMN IS MUTUALLY EXCLUSIVE IF fULL
. · ··· · ·<::> SUPPLY LEVEL OF DAM IN ROW EXCEEDS THIS VALUE-FT. _::::: Ji~~-·''. VALUE IN BRACKET REFERS TO APPROXIMATE DAM UEIGHT •
TYONE
.... ·-:.···
MUTUALLY EXCLUSIVE DEVELOPMENT ALTERNATIVES
FIGURE8.3 ~~~~~
,,..
-
,_
~
-
-
1000
800
G'"
Q 600
IJit ..
~ u
1500
1000 -IDQ ..
~ ....
!J)
0 u 500
DEVIL CANYON
1000 2000 3000
RESERVOIR STORAGE ( 103x A F)
. HIGH DEVIL CANYON
1000
LF.:GENO
• COST OI!VELOPED o
0
rURTESCTLY FROM
ENGINC::.ERING LAY
COST BASED ON AOJUSfMENTS TO
O VALUES DETERMINED FROM LAYOUTS
1500
DAMSITE COST VS RESERVOIR STORAGE CURVES
8.4 [i] FLGURE
8-70
I
I
....
i -
2400
2000
~
2 1600 .. ..
1-8 1200
800
400
1860 LEGEND
e COST DEVELOPED DIRECTLY FROM
ENGINEERING LAYOUTS
COST BASED ON ADJUSTMEI rrs TO
O VALUES DETERMINED f"ROt I LAYOUTS
0~--~----~----~--_.----~--~----~--~ 0 2000 4000 6000 8000 10000 12000 14000
RESERVOIR STORAGE ( I03x A F )
WATANA
1500
1390
1000
..
500
1000 2000 3000 4000
RESERVOIR STORAGE (I03x A F)
SUSITNA lii
DAMSITE COST VS RESERVOIR STORAGE CURVES
r.·iiJ·Im,.
FIGURE 8.5 ll II
~--------------------------------------------------------------------~ .-. .., .... . -.. ~
L I
L
r -
L
L
L
L
-I
I
L
~
1060
LEGEND
e COST DEVELOPED DIRECTLY FROM
ENGINEER! NG LAYOUTS
COST BASED ON ADJUSTMENTS 10
0 VALUES DETERMINED FROM LAYOUTS
0 o~--~~~--~~~--~~~--~800~---~o~oo----~--_.~
RESERVOIR STORAGE ( I03x A F)
VEE
800
600
~ L500
-400 ...
~ 350
(.)
200
200 400 600 800 1000 1200 1400
RESERVOIR STORAGE ( 103x AF}
MACLAREN
800
1000 2000 3000 4000
RESERVOIR STORAGE (I03 x AF)
5000
DENALI
FIGURE 8JiJ DAMSITE COST VS RESERVOIR STORAGE CURVES
8-72
-
-
r
....
-
-
-
-
2200 FT. WATANA 800 MW
'I" 2 MILES
.;----1475 FT.
~--RE -REGULATION DAM
TUNNEL
SCHEME
#
I.
DEVIL CANYON
550 MW
2 TUNNELS
38 FT. DIAMETER
800 MW-70 MW
2.
2 TUNNELS 115U MW
38 FT. CIAMETER
·-RE-REGULATION DAM 3.
30 MW
300 MW
30 FT. DIAMETER
800 MW
4.
2 TUNNELS 365 MW
24 FT. DIAMETER
SCHEMATIC REPRESENTATION
OF CONCEPTUAL TUNNEL SCHEMES
c:IGURE 8.7
8-
J ...
~
L
.L
~
I
4000
LEGEND
STAGE I STAGE 2 o---o PLAN El
o--o PLAN E2
o----o PLAN E3 E3.2 ~
o---o PLAN E4
I 3
~
I
·I
I
~
I
3000 /
z
0
:J
d
::iE
I .._
(/)
8zooo
....J
~
0:
<[
(j
-1
~ ~
IOOor-----------------+-----------------~-----------------+--~
0~ ______ _. ________ ._ __ ·----~--------------------._------~--~
0 1000 2000 3000 4000 5000
AVERAGE ANNUAL ENERGY - G WH
CAPITAL COST VERSUS ENERGY PLOTS
FOR ENVIRONMENTAL SUSITNA BASIN PLANS
FIGURE
6000
8.8 [jjJ
F"'
,....
-
-
F""
,_
-
3
3:
:E
0 2
0
0
I
>-
1-
0
f1
<(
(.J
0
10
8
:I:
3:6 (!)
0
0
0
>-
(!)
:!i4 z w
2
715
103
1980 1990
LEGEND:
D HYDROELECTRIC
M~~~~tJl COAL FIRED THERMAL
e:::z:J GAS FIRED THERMAL
2000
• OIL FIRED THERMAL{ NOT SHOWN ON ENERGY DIAGRAM
NOTE : RESULTS OBTAINED FROM
OGPS RUN L8J9
DEVIL CANYON
(400 MW)
WATANA"I ( 400 MW)
EXISTING a COMMITTED
2010
o~--_.-------------------------------------------------·--------------~ 1980 1990 2000
TIME
GENERATION SCENARIO WITH SUSITNA PLAN E 1.3
-MEDIUM LOAD FORECAST-
FIGURE 8.9
8-75
2010
-
-
-
-·
:~
~
:E 2
0
0
0
>-....
0 <t I a.. <t
(..)
0
10
8
:I:
~6
0
0
Q
>-(!)
ffi 4 z
I.LJ
2
715
103
1980 1990
LEGEND:
D HYDROELECTRIC
(f(f~~H COAL FIRED THERMAL
~ GAS FiRED THERMAL
2000
• OIL FIRED THERMAL( NOT SHOWN ON ENERGY DIAGRAM
NOTE: RESULTS OBTAINED FROM
OGPS RUN L601
2230
2010
VEE(400 MW)
HIGH DEVIL CANYON· I (400 MW)
TIME
GENERATlON SCENARIO WITH SUSITNA PLAN E 2.3
-MEDIUM LOAD FORECAST-
FIGURE
8-76
2010
9.10 [i]
-
~~
-
~
-
-
-
-
r-
-
-
-
3
3:
:s 2
0
0
0
>-1-
(.)
~
oct u 715
103
0
10
a
J:
3: 6
(!)
0
0
Q
>-
(!)
ffi4 z
LaJ
2
1980 1990
LEGEND'
D HYDROELECTRIC
~~tf~I~~~ COAL FIRED THERMAL
[Z] GAS FIRED THERMAL
2000
• OIL FIRED THERMAL { NOT SHOWN ON ENERGY DIAGRAM
NOTE : RESULTS OBTAINED FROM
OGPS RUN L607
TUNNEL(380 MW)
WATANA -I { 400 M W)
EXISTING a COMMITTED
2010
0~--~------------------------------------------------------------~ 1980 1990 2000
TIME
GENERATION SCENARIO WITH SUSITNA PLAN E3.1
-MEDIUM LOAD FORECAST-
FIGURE 8.11
P. 77
2010
-
-
-
-
I~
1.2
31: ::e
0
0
Q
• .e >-!::
(.)
Ci
<I
0
::r: ;::
(!)
0
0
.4
6
Q 4
I
>-(!)
0::: w z w
2
1980
1980
1990
LEGEND:
D HYDROELECTRIC
~~Hl)TI COAL FIRED THERMAL
D GAS FIRED THERMAL
2000
• OIL FIRED THERMAL (NOT SHOWN ON ENERGY DIAGRAM)
NOTE: RESULTS OBTAINED FROM
OGPS RUN LC07
1990
TIME
DEVIL CANYON
{400MW)
WATANA (400 MW)
EXISTING 8. COMMITTED HYDRO
2000
1272
2010
2010
GENERATION SCENARIO WITH SUSITNA PLAN E 1.5
-LOW LOAD FORECAST-
FIGURE 8.12 [ii
C-78
-I
r.m ,
~
I
I
~
~
I 1
..
3.5
3
:=
~
0
0
Q 2
I
)-
1-
u
~
oct (.)I
:I:
3:
(!)
0
0
0
a
16
12
1 a
>-
(!)
0::
UJ z w
4
949
715
103
1980
1980
145
1990
LEGEND:
D HYDROELECTRIC
IJ!lfH COAL FIRED THERMAL
IZ:J GAS FIRED THERMAL
2000
-OIL Fl RED THERMAL( NOT SHOWN ON ENERGY DIAGRAM)
NOTE: RESULTS OBTAINED FROM
OGPS RUN LA73
1990
TIME
2000
DEVIL CANYON
( 400 MW)
WATANA-2 (400 MW)
WATANA-1 (400 MW)
2010
2010
GENIERATION SCENARIO WITH SUSITNA PLAN E 1.3
HIGH LOAD FORECAST
FIGURE 8.13.
B-79
,_
-
-
' .. -...
-
-
-
r700
.....
1.11 1..00 ..
1L
; 1600
J! 1-400 0
G£.N~AL ARRANGE.ME.NT ~ ~ 1~00
300~-------------------
SC.A.l-E.'A .j 1'200 loJ
LONGITUOINA.L SE.CT~ON T~RU ~Of" O~M
~ ..... , &
8-80 --·
------1500
1-~
~
%
0
~ ~ .... ..,
.... oo
1500
i 1400
1!>00
! z l'lOO
0 t= 1100
~ j 1000
<\00
eoo
>.PPROAC. ...
1&1-----
-
,.,..
.-
~
1~0 t'------
... 1400
i 1&00 ~--------------------~r'-~-~~--~~~---~~----------
; 1200
z Q 1100
~ 1000
~
"'
:; • ...
!
z
0 ;:
~
ol
..J
"
~ "'
~ e.
I;) ~ ;r 2!! .··
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, •• 1
IJU1
SECTION Tl-lr<U DAM
SCALE. : e.
POWER FACILI TIE.S PROFILE.
5CAI-E: F.!>
SPILLWAY PROFILE.
!GA.~-£: &
PLATE
::1.!100 -«200
2100
2000 ... .. .. ... 1900
~ leo<.
1700
:1200
:1100
2000 ----...
~-:I .... '""'
! J&QO
l
GENE'..Rt..L AQR.A.NGE.MENT 0 1700
~ 1600 > Ill
J 1'500 Ill
, .. o;,
0
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SE.CTION A-A.
SCAU:C
...
~ 2!QX~--------------------------~~~~~---------
-------------------------------------------------~~~~------------------------------------~~~~~=---=-------&~~~~~~:::~~
ORIGIN ... L. GAO liND SI • .'A~P:.:."'::.C.::.E.=.. ____ ...J~-::...:--------------------------------,,.t:;L.,L.::_-------.1
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GltOU"T CUiiilT ... u•• -~ \ CiR.OVI (';.t..L..L..Dil"t'
lf-~·ti
SECTION TI-II<U DAM
SCAL.E:P.>
I!!CO = Q.~-.. ....... Gie aN F=IE.aT
POWE:f2. FAC.ILITIE.S PROFI!_E.
~C:AL.E.' e,
~!>00
2200
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151100
1&00
1700 ~----------------------------------~ .. ~-------i~~~--~~----------------.-.. ~·~uu A L~~
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,-;:-~~L__L __ J_ __ OL--L-~-~--L--&00J-~L__L __ C~~-..,-L~--~~~--~,N~F-£Le-T~---L--I500~--~~L--L---L-~-l
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-
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19CD
....
-------<~!100
i
LSTAGE. U
SPILL..W~Y
GENeRAL ARRANG~MENT
SC.AL.E. 'A C.tU.:>T EL 22'25'
&!>00 ........ -----
2200 ·--------
2100 s 2000 ..
! I "'lCC
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Q ~oao
~ ~ 1700
ol
[AT ~ OF DAM {STAGE. ~)
·-·~;----=-.... ---·-----------·---·------·-·-·-·-·-·---------"-·-·-·-----·-·-·-----·-·-·---·------··-·-----
-~-----
tl
I
... -_---.........
,, E.li.CA.VA."TION FOR COQ.It
~-====-:..-====:a-=..:--= . -" "':; -=:-lff-=
1700 -"J ~--------------------·----------·------------~~~~----------------------------------~~S"~~--~--GROUT GALL..£RIES
<=--;r===---=-~~-------------------------------------------~~~~-------------------7~~~-,,
1400
!: -----------------------------------------------*~--~====~~=====-~~f----II _.-="'===="!:==
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'l.'ZOO
2100
2000
1900
1-~1800
!ITOO
;z
01.-c>o .. ~l'!iOO a,40:)
I~
... -------·
LONGITUDINAL SECTION T~RU ~OF DAM
~GAL.£:B
----
HO~L. MA)<.OPE.QATIHG
i.E.~L.-EL. 2'2CX>'
'2· ~!) r:>IA.~ LIW!oO
TtJtmE:L-5
STAGE. I SPIL.LWA.Y
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~
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SPILLWAY PROFILE.
SCA-t...&.: I!>
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2100
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z
0 ~000 ~ 1700 ~ ~
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1: I /4-17 1 DIA..CCJ ... C.~E.TE. -... ---
~illl,__.:t,;;5=-::.::.::.===~ '-'"ED TUNNEl..!!>
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et· UNIT INT ... !<£~ Lt.· n' O!"-. cow:12Eft ~ I TRAI-I!>~I=IM!R .AND lll2iiJ'T
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7 '-?.·21 OtA TUN~~~!~.$ ....;.;
{STAGI!.I
POWER FACILI TIE.S PI<OFILE.
3-C,II.I..E: e
AlASKA POWER AUTHORITY
.... ITaA MYOaO!ItiCYI;tC PRO.IICf
WATANA
STAGED FILL DAM
-
!"""'
:;
IL
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z
Q
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1500
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1~00
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---j
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= 1400 1&.
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7
LONGITUDINAL SE.CT ION T~ QU ct OF DAM
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C:l-l.a..tNA.COE. '"' FEE.,.
POWER FACILITIES PROFILE.
SCA.l..E.: !!>
NOR........_ MA.)(.
w; L.. E.L rrso~
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SPILLWAY PROFILE
eco I'"GT
sc;:A.Ui: ~
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150:>
~------("'\.. f: El-1050' ---....:::J-.
PLATE 4
HIGH DEVIL CANYON
HYDRO DEVELOPMENT
.....
-
.... 1'1100
1500
-
....
~~
GEN~~AL AQQANG~M~NT
SLOPE.
LONGITUDINAL SE.CTIC.N TI-IR.U p OF DAM
$CALf. : e,
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SE.CTION THR.U DAM
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IU.. 'Z !oo4o.
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POWEQ FAClUTE.S PROFILa
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&CAL..a.: e.
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~----------------------------------~----1..& e o!!~~~~oo~._;~~ ~UT
/t <O•• 1 •nnr.t ..
PLATE 5 IIIII ALASKA POWER AUTHORITY
t----::.,1 u=u TII-:-::::-:A •y D::-="::":':'11 D H-::-:-::-::-0 C T a--::--:-0 C • 11-0JE C--IT
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! '1100
2
0 2000 j:
~ 1900 ~ •&oo -
G~NERAL ARRANGEM~NT
SCALE.: ,.,
5U~I'-..:&
LONGITUDINAL SECTION THRU ~ OF MAIN DAM
SCALE: 8
ti
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SECTION THRU MAIN
sc;4.u:. , e
0 !DO l!oOO
GWA.INAG&. IN F&ET
POWE.R FACILITIE.S PROFILE.
SPILLWAY Pr<t:>FIL£
SCALE.: e.
1!500
DAM
-
-
-
"""
-I
-
=t
'I 'ZOO
__ /
/ /:
;'
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-'2500
MACLARE.N
GENSRAL ARRANGEMENT
SCALE: A
.._.
DAM CROSS 5E..CTI()N
SPIU...WA'( CONTilOL.
STRUCTUIU.
SECTION 8·B
~GAL.£.' C:
Sc.A. L.E. : C.
SECTION A-A
SECTION C-C
-
-
-
-
-
N c-c -
-
-r A~~ TAILWAn.IZ
I!L..'Z!ICO' --
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SCALE C 0 100 ~ FEET
DAM CQOSS SECTION
SGAO..it' e>
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MOUNTED ~E.S
SE.CTION 0·0
5GAI..E.' c
ALASKA POWER AUTHORITY
DENALI a MACLAREN
HYDRO DEVELOPMENTS
-
-
-
-
t-400
-
,c;.DO
rtoo -
SCl-IE.ME ~ PLt>..N
$GAL£ 0 2 MILE
-------
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-----· ------EL-1410:.'
SUSITNA
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.to.t..L t=>t..ANS -o Woo.Yc
CONC&PTU~ STUDY
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GENERAL ARRANG~M~~T
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SCALE 0 •oo 800 FEET
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SPILLWAY PROFILE
SC"'<-£.: A
SE.CTION A·A
TYPICAL TUNNEL SECTIONS(I .. oorltls.c .. LII.)
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DETAIL 'A.
TYPICAL TUNNEL SECTIONS
(NOT TO sc ... ._e;)
A •
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~ '----'---·-'----
0
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-
OISTA.WC.It IN. Mll..ltS
Tt..INNE.L ALIGNMENT --------------------------
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DEVIL CANYON POWER FACILITIES PROFILE'
SCAl-E.: A
!:::!OTE:
41,.1.. STI:ZUC:TURJ>.l. MD SuPI"'RT
DEiAH.S ARE CONCEPT tJA.L AWD
FOQ. STUDV PURPOSES <::lN!..'t.
PLATE 9
PREFERRED TUNNEL
SCHEME 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 Hydroelectric 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 invol~es
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-l 1ine. A delay in
this date would mean that additional thermal units would have to be brought
on-line resulting in an increase in the cost of power to the consumer. This
first stage wou·l d be fol1 owed by expanding the powerhouse capacity to 800 fviW by
1996 and possibly the construction of are-regulation 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 Devil Canyon dam to the year 2002 or pos-
sib'ly even 2005. These latter two dates correspond respectively to the 1ow load
forecast and the extreme 1 ow forecast incorporating an increased 1 eve 1 of 1 oad
management and conservation. For actual load growth rates higher than the
medium load forecasts, construction of the Devil Canyon dam could be advanced to
1998.
Although it has been determined that this development 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, say, a five year
basis. It should also be stressed that the dam heights and installed capacities
quoted above are essentially representative orders of maynitude at this stage of
project planning. These key parameters are subject to modification as the more
detailed project optimization studies are conducted during 1981. The dam type
selected for the Devil 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 well 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 1 ayouts are being compared from both techni ca 1 and economic vi e\vpoi nts and
this comparison will lead to the selection of possibly two or three basic
1 ayouts at each site for study in more detail.
9-1
-
-
-
At this early stage certain layouts are discerned to be more attractive than
their counterparts. Of these, a single layout at each of the Watana and Devi 1
Canyon sites has been selected as representative of the possible final develop-
ment, and is described in this section.
These layouts are indicative of the present stage of the study. Much field work
is 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) Site Geology
The dam site at Watana is underlain by a dioritic intrusion (pluton).
The site has a favorable configuration 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 immediate site. Following 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
investigate~ in the 1981 program.
The surf1cial 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 tiver
channel 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 distinct 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 altered by injection of felsite 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 1 i es predominant 1 y on sound diorite wh·i 1 e some
portions of the downstream shell overlay andesite. The upper 10 to
40 feet of rock is weathered. The seismic considerations 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 assumed that up
9-2
-
-
....
to 40 feet of rock excavation will be required under the impervious
core and the jupporting filters to found the dam on sound competent
rock. This type of foundation preparation is considered normal for
large dams of comparable size. Shear zones and joints within the
rock foundation have been located and will 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 also be present under the river channel. The data
indicates that this is 11 Warmu 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 re 1 i ct channe 1 area wi 11 be be 1 ow
the reservoir level. Further investigations will be undertaken to
precisely def~~e the characteristics of the channel. However, the
data collected to date does not indicate that it will have any major
impact on the feasibility of the site.
The rock conditions in the left bank, where the underground power-
house is currently proposed, are favorable, and the powerhouse cavern
will require only nominal support. However, additional investiga-
tions 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.
Materials for construction of a fill dam and related concrete struc-
tures are available \'lithin 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
riverbed 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/rockfill structure with the majority of the
materials excavated from selected borrow areas, but with 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
mater·ials. The maximum he·ight of the dam above the foundation is
approximately 880 feet, the crest elevation is 2,225 feet 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 overall volume of the dam is currently estimated as approximately
9-3
-
-
63 million cubic yards. The dam is founded on sound bedrock.
Upstream and downstream cofferdams are founded on the river alluvium
and integrated with the main 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 will also be utilized for final closure
together with mass concrete plugs constructed within the tunnels in
a 1 i gnment with the dam grout curtain.
The river wi 11 be diverted upstream by means of a ,~ock/ earthfi 11
cofferdam founded on the riverbed alluvium. Cutoff beneath the cof-
ferdam is formed by a slurry trench to rock.
( v) Spillway
The spillway is located on the right bank and designed to pass the
routed 1:10,000 year frequency design flood of approximately 115,000
cfs without damage to any of the project structures. The spi 11way is
also capable of passing flows cf 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 some downstream erosion within the river valley would
be accepted.
The spillway consists of a gate structure, with three vertical 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 r·iver-
bed.
(vi) Power Facilities
-Intake
The intake is situated upstream of the right abutment of the dam.
It is set deep within the rock and is similar in structure to the
Devil Canyon intake with provision for drawing off water at ditfer-
ent levels within the fluctuating reservoir.
9-4
1
~I
l
!
-
-
~-
-Penstocks
Four concrete-lined tunnel penstocks descend at an inclination of
55° and terminate in steel liners at the powerhouse feeding the
high pressure turbines.
-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.
-Tai I race
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 Releases
At the present time there is prov1 s1on made for emergency drawdown of
the Watana reservoir. This will take the form of an intermediate
level reservoir outlet. Flows are controlled by high pressure gates
located in an underground chamber, and a concrete-lined tunnel
discharges into the diversion tunnel, downstream of the concrete
plug. Small re1eases, 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 narrow V-shaped canyon cut through relatively
homogeneous argillite and gray\'lacke. 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 fcrces, 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 vailey above the V-shaped canyon, while
deposits in the canyon itself are limited to a large gravel bar just
upstream of the canyon entrance, and boulder and talus deposits at
the base of the canyon walls.
9-5
I~
-
....
....
-
.....
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 are 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.
Two minor 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 zones, is not well defined. Further field
mapping in 1981 should clarify this.
(ii) Geotechnical Aspects
The Devil Canyon dam site lies on argillite and graywacke 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 metamor'phism. 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 dental excavation of badly crushed and altered rock will be nec-
essary to provide adequate bearing surfaces for the dam. Ovet~burden
within the narrow V-section of the va11ey is minimal.
The left bank plateau, which is the location of a saddle dam, has a
buried river channel paralleling the river. The overburden reaches
90 feet under a small lake in this area and construction of the
saddle dam will require excavation of considerable amounts of till
and lake deposits or construction of a cutoff extending down to
bedrock. Seepage control \vill be effected by two methods: first, by
general contact and consolidation grouting to control flow at the dam
foundation contact, and second by a deep grout curtain with
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 ~rogram 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 Cheechako Creek
(approximately 0.25 miles upstream), may be sources of a substantial
portion of impervious material for the earthfill saddle dam.
( i i i ) Dam
The main dam is currently proposed as a thin concrete 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
crmm cantilever is 90 feet. The geometry of the arch corresponds to
a two center· configuration which is compatible ~'lith the assymetric
transverse profile of the valley.
9-6
1
1
I
-
-
-
-
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 rockfi11 structure with an impervious core. It abuts
and surrounds the concrete thrust b 1 ock with the core wrapping the
concrete to provide a seal. Overburden will.be excavated to allow
the core to be founded on the deep underlying bedrock.
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 spi 1 h'lay. 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 for
Watana with twin concrete-lined tunnels and upstream control
structures. ~offerdams are as described previously. Full use of
storage at Watana will be used to safeguard construction at Devil
Canyon.
( v) Spil h'lays
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 cancrete structure contiguous with the chute. 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 spillway 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
level of the dam crest wave wall.
9-7
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-
-
-
-
-
I
Beyond the rockfill saddle dam on the left abutment a channel is
excavated in the rock and runs approximately 1,400 feet downstream i.
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 l
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 capabi 1 ity 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\<to sets of guides set one behind the other. By rais-
ing and lowering the shutters, openings can be created by varying
levels over the height of the structure. These shutters will 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 lining
changes to steel in order to prevent see~age into the main power
cavern and to contain the high internal pressures in thP vicinity
of the fractured rock caused by blasting the powerhouse excava-
tion.
-Pov1erhouse
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 lOO MW turbine/generator units. The
turbines are vertically mounted Francis type units driving overhead
umbrella type generators serviced by an overhead crane travellin9
the length of the powerha11 and end service bay. Switchgear, minor
offices, service areas and a workshop are housed in this area.
Upstream bus duct galleries are inclineG frQm yenerator floor level
at the power cavern to the transformer ga 11 ery running the 1 ength
of the powerhouse and set above the penstocks. Vertical shafts are
raised from the draft tubes to the downstream side of the power-
house and these incorporate vertical guides for the operation of
closure gates within the draft tubes and function as surge shafts
during changes of flow within the 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 the
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
driven from the bottom of the river gorge.
means of an elevator operating between the
the administration building.
Tailrace
inclined rock tunnt~l
Personnel access is by
powerhouse cavern lnd
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 b~ made
through Howell Bunger valves set close to the base of the dam rtnd
discharging freely into the river valley.
9.3 -Construction Schedules
At this stage of the study, a preliminary assessment of the construction ;ched-
ules for the Watana anJ Devil Canyon dams has been made. The main objecti te 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 developed during the 1981 studies.
In developing these preliminary schedules, roughly 70 major construction activi-
ti1es were identified and the applicable quantities such as excavation, borrow
and concrete volumes were determined. Construction durations were then estimat-
ed using historical records as backup and the expertise of senior schedule~
p1anners, estimators and design staff. A critical path logic diagram was
deve1oped Tram those activities and the project duration was determined. ne
,...., critical or near critical activity durations were further reviewed and ref·,ned
as needed. These construction logic diagrams are coded so that they may bE~
incorporated into a computerized system for the more detai1ed studies to b~ con-
ducted during 1981.
The schedules developed are described below:
(a) Watana Rockfill Dam
As shown in Figure 9.1, it is expected to take approximately 11 years to
complete construct ion of the Watana dam from the start of an access roc:d to
the testing and commissioning of all the generating units. Principal com-
ponents of the schedule include 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 ~o
15 years estimated in the COE 1979 report ( ). The most important di f-
ferences that the COE provided for a 4-1/2 year period of access road c~m
structian prior to any work being done at the site. In this study, bectluse
9-9
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I"""
I
(b)
(c)
of the economic advantage to be gained from an early on-line date, a 11 fast
track~~ approach has been adopted during the early stages of construction.
This involves 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 im-
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 schedule shows the earliest cate power production from the Watana dam
caul d start waul d be January 1993. This is based on start ·i ng construction
of access roads in early 1985 as soon as the FERC license is received.
Devi 1 Canyon Thin Arch uam.
As shown in Figure 9.2, it will take approximately 9 years to complete the
dam from the start of constructlng 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 additional 1-1/2 years for consti'uction of a
main access road from the Watana site.
The key elements in determining the overall schedule are the construction
of diversion tunnels, cofferdams, the excavation and preparation of the
foundation and the placement of the corcrete dam. For purposes of estimat-
ing activity durations, it is assumed that embankment and curtain grouting
will be done through vert i ca 1 access shafts on each embankment.
lnterpretation 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" which controls project duration. During the continuing 1981 studies
the 11 non-critical 11 items will be scheduled to take into account resource
availability and financial and climatic aspects. This will result in the
"non-critical .. items being more rigidly 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 fl0\'1
characteristics which are important from an environmental point of view.
9-10
-
....
Figure!s 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
Railbe!lt 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
periocl of less than a month in a given year. At this stage of development, the
Devil Canyon spillway would 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 flows include water coming from the turbines and
water passing over the spillway. It will be noted that daily fluctuations are
kept to a minimum for the Watana 400 MW development. Outflows from the Devil
Canyon dam in the fuli 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 Susi tna Basin has been considered as a potentia 1 hydroe 1 e"ctri c
development site not only because of the economics and energy potential but
a.lso because of its relative compatabi lity with the environment. Compared
to other potential large hydro development sites (e.g. Rampart on the Yukon
R.iver or Million Dollar on the Copper River). The Upper Susitna has less
potential environmental impact. A comparison 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
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I
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I
As with any type of major development, hydroelecttic projects can cause and
have elsewhere caused significant 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 by the selection of
the Upper Susitna Basin.
For studies within the Susitna Basin it is still important that environmen-
tal input still be provided into the decision m&king process. To date, the
major environmental imput into the Susitna studies has been directed to-
wards 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) wili be contained in the environmental section of the feasibi 1-
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 ne~essitated judgements and
tradeoffs. To facilitate a rational assessment, these judgements and
tradeoffs have been defined as clearly as possible. In some instances,
economic and environmental preferences recommended similar action; an
example being the Watana/Devil Canyon plan where the reservoirs are basic-
ally confined to the river valley. In other instances a specific decision
has been made that an economic expenditure is required to ~etain environ-
mental compatibility; examples being multilevel intake structures to allow
for some temperature control of discharge water and the provision for down-
stream daily re-regulation of flows. In still 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 of $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 final feasibility report. This report will 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 Environmental Impact State-
ment on the Watana/Devil Canyon Development. The information gathered by
the COE in this study is being enhanced by insight obtained from the 1980
studies and in areas where study effort is continuing as part of the pre-
sent study.
(b) fudro logy
Under existing conditions seasonal variation of flJws in the Susitna is 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 aevelopment, downstream flows between Devil Canyon
and the confluence of the Talkeetna/Chulitna rivers will be relatively con-
stant. Figures 9.3 -9.5 show the differences between inflows and outflows
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 without the project are shown in Figures 9.6 to 9.8.
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 with suspended solids in the releases at Devil Canyon Dam
pr·ojected 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 will be adjusted to approach the natur-
F al river water temperatures through the incorporation of multilevel intake
structures. Even so, slight changes in discharge temperatures can be ex-
pected at cartain times of the year, the extent to be predicted by means of
a reservo·i r computer mode 1 present 1 y 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 fluctuat~ons in flow by means of operating the down-
stream powerhouse as a base load plaut or incorporating a re-regulation
dam. As this constraint has been incorporated into the proposed Watana/
De~ vi 1 Canyon development, potentia 1 impacts associ a ted with daily fl uctua-
tions due to peaking operations are avoided.
9-13
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(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 engineers 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) Design Features
The two major design features currently 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 particular 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 outlined 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
I
i
j
]
1
1
Month
JAN
FEB
MAR
APR
MAY
JUN
JUl
AUG
SEP
OCT
NOV
\.0 DEC
I
~
01
Note:
( 1) Total
TABLE 9.1 -OUTflOWS FROM WATANA/OEVIL CANYON D£VELOPME.NT
STAG£ 1 WATANA 400 MW
Average Outflow (cfs)
Monthly Average
Peak
Average Daill::
Inflow (cfs) Monthly Off peak
1147 7699 7834 7603
971 7409 7538 7316
889 6758 687} 6676
11113 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, compensatic'1 flows and spills.
Average
Monthly
SpiJls (cfs)
1779
6582
2744
l
Month
JAN
FEB
MAR
APR
MAY
JUN
JUL
AUG
SEP
OCT
NOV
DEC
Note:
1
TABL[ 9,2 -OUTFLOWS FROM WATANA/DEVIL CANYON DEVELOPMENT
STAGE 2 WATANA 800 MW
Average OUTFLOW (cfs) 1
Monthly Average Average Da1l~
Inflow (cfs) Monthly Peak oHeeak
1147 7699 15663 2011
971 7409 14979 2001
889 6758 H419 2000
1103 6168 12003 2000
10406 5689 11l703 2108
23093 5571 11l524 2o:n
20344 8227 11337 6006
18012 14263 15224 13576
10614 10299 12358 8827
4394 6503 12783 2017
1962 7497 15139 2039
HBS 8237 167.H 2166
(-1) Total outflow includes powerhouse flows, compensation flmvs and spills.
] ]
Average
Monthly
Spills (cfs)
134
431
-
-
-
-
TABLE 9.3 -OUTFLOWS FROM WATANA/OEVIL ~ANYON DEVELOPMENT
STAGE 3 DEVIL CANYON 400 MW
Average AveraQe Average
Monthly Monthly Monthly
Month Inflow (cfs) Outflow (cfs) Seills (cfs)
JAN 8595 8666
FEB 8280 9216
MAR 7576 7394
APR 6988 6833
MAY 8235 781)6
JUN 9294 8796 24
JUL 9524 8967 958
AUG 13534 16239 7129
SEP 11188 13491 4180
OCT 7838 7950
NOV 8462 8889
DEC 9211 9383
(1) Operated as a base load plant. Minimal daily fluctuations.
(2) Total outflow includes powerhouse flows, compensation flows
and spills.
9-17
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1984
YEAR
3
MAIN ACCESS
1985
PICNEER ROAD
1986
2
1987
3
1988
r----------------------·-------J--------------·--r------·----···-----·----------+-------------·---········· ·------
CONSTRUCTION ACCESS ~··········· .....
r----------·--·-·----·-·· -----------+------·---------------·-··-------·-·--···----·-···-·······--······· -·
DIVERSION TUNNELS •••••••••••a••••••
1--------·----------------------.. ------· -----------------~-~----------.. -oE WATER--------~---------·
COFFERDAMS -•uu EXCAW tON INSIDE C
1----------------------+--·------· ·----~'!:~AV~~I-A!!~~_iN~t-r-----f·-----__ -·--·-·-· _____ _
If 2 -•l-+--· --~r------------
MAIN DAM ununnnn11• nuunntnu
-----------+---------. -----1---~---r------·-·--···----····--------·--·-·-
SERVICE SPILLWAY --~----~---···--······-·--·--· ____ ,_______ t··
INTAKES ----~--------~-----=-p~~_s;~--~-K~---==-~-----------· -------+------~~:t~ ..•• -~=~ ~-___ • J. =•: +==---
POWERHOUSE
I
t------···-···-----------------------1.-------+···------·--·····-··--·· ··--·---···--·--·····r------·-····--·-!--------·······
TAILRACE j --~----·--·-·--··-···· ··-··------·-·-----·
t---------------,---····------------------------··-+-·· . -----------··-··---........•
TURBINE /GENE~~T0~-------------1__ __L . -----
INITIAL IMPOUNDMENT I
t----------------------~------·r---·--·----+-------,..........--·-·-----·---· -------
TEST AND COMMISSION
-~--------------+-------1-------·------'----··--·~'--·-----····~-.. . .... ·····--····· .... --· ·-·····----................. .
1-----------------------1-·-·--·-----------·-····---------·· .................. ..
NOTES:
l MAIN DAM SClHEWLE BASED ON FI~L PLACEMENT RATES OF
2.5 TO 3.0 MILLION CUBIC YARDS PER MONTH
2. FIVE 10 SIX MONTH FILL PLACEMENT SEASON ASSUMED
3. BASED ON AGCESS FROM DENALI HIGHWAY AND ASSUMES
OVERLAND WINTER ACCESS AND AIRCRAFT SUPPORT
DURING 1985
~-la
~EGEND KEY
••na• CRtllCAL ACTIVITIES
-OTHER ACTIVITIES
WATANA FILL DAM PRELIMtNARY CO"
j 1988 1989
5
I 1990 1991
6
J
···+
t ~ t ~· ----------------~~--------~·
....
I
• I
, NARY CONSTRUCTION SCHEDULE
1
1992
8
1993
9
J994 1995
10 II
-
-YEAR
I 2 3 4 5 6
I 1-+ I WATANA/OEVILCANYON ROAD
MAIN ACCESS ............ ~:lUll~~--+ ----------f--·
'
CONSTRUCTION ACCESS I
II +-----·~---~-... ·-·
DIVERSION TUNNELS .............
-----oEtATER j -~-:---------------
COFFERDAMS II
--f EXCAVATION IN I DE COFFERDAM /FOUNDATION I
EXC :-\VATE ABUTMEN~S-, 1--I 2 I I ...... ~ ........ MAIN DAM CONCRET
MAIN DAM ......... 1111111111 IIIIUIIII
\ -
SERVICE SPILLWAY
--_ ---+ ---
EMERGENCY SPILLWAY
INTAKES 8 PENSTOCKS
SADDLE DAM -
--
POWERHOUSE J
--~. -----r-------
TAILR~E I
·---~-
'
TURBINE GENERATOR ....
INITIAL IMPOUNDMENT -
TEST AND COMMISSION
----·
I ---
NOTES: LEGEND KEY
I. SCHEDULE ASSUMES DENALI-WATANA HIGHWAY ALREADY lllllltl CRITICAL ACTIVITIES I. AVAILABLE, -oTHER ACTIVITIES
2. BASED UPON SIX MONTH CONCRETE PLACEMENT SEASON.
-
DEVIL CANYON THIN ARCH DAM PREUMIN. -. ---·
I 9-19
j
I'~;
6 7 8 9 i
I ;<
L .
~~=i-
---~------·-·--···-f------.. ·-·-·· -----·--·---------
--------f--------
··-----' !
r /FOUNDATION PrEPA~ATION
----
I
<,
~ DAM CONCRETE· I -1811111111 1 .......... .. ....... j
-5
-+-----f.--------
~
:""' "·--····-. r----
I '
I ' ----
I i
-.1 ····---+~------.~
I'""
-....-....--·--·"'-"
------... -I
I
-------------------_.. ------·--
I -I
UNIT'I ON LINF ------
ff'~ LINE I .. ON LINE -f--1ur .T 4 OJifiJlift--f---
Ill Ill ti
;
; -· ·----·-f-·----··-------------------1----r----
--r--------------------i
I
i
' -
KEY /EMU EST START OF ACTIVITY
/EMU EST FINISH Of ACTIVITY
""" ~LATEST FINISH OF ACTIVITY
--fill PREUMINARY CONSTRUCTION SCHEDULE FIGURE 9.2
-!
---------------------------·-----·--··-------~
J
J
J
I
I"""
-
•
>o
~ CJ
~ o _.'I ""''3r.~ O~'l ·"':) :,o-;-1--'-,l"'')cr~ "2 -'-;-I "'·) ~""3.-'-1"'3"':.·-.4 -'-.1 """9 '"'S 'j__.L-; ---.. =r ____ ~-----;;-'"-;-i~96:::-;1__._,1r;;~~l)2" I ·J~3 i ·JI)4 I 'J6~
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r'l
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LLO
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w
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'LL N
z oo 0 -.
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<(~
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t.w
..JO
W c~
C)
0
0
C\1
AVERAGE MONTHLY ENE
-------··-~·
-
~ n n ~ rr n J It A ,11
11 JL l Jl PJ
fl
~l ~ Jl J l J I l 1\ I I ) I '"' ~ J I ~ ) u rJ ~I b ~ [(__ hc.._J ~J ~ h_ ~J rt_ w IL ~ " " I"" . .-.... 'r , rr ' r '" , r.n '" -r
AVERAGE MONTHLY I NF
I I I H I I • ~ N N rJ N ~ ~ ~ V'-N ~ Is---~ ~~ ~
r £"" • r. r.-: ' " "
... r " ' "' 1950 1'351 19 ... 2 19.J3 19:.J4 J9_,:.J 13.JF) 19.J7 19-J!) 19::J9 1960 1361 1)1)2 19113 1964 136;.>
AVERAGE MONTHLY DIS!
~~~f~fl\/~f~l~f\fl\/\l\/1\f\ri\/1\J\f v v.~ v ~ ~ ~ ~ ~ tl ~ ~ u v ~ tl
1950 i"J~I 1952 1953 1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 •9'>4 1965
AVERAGE MONTHLY ELE
NOTE: WATER YEAR OCT.-SEPT.
STAGE 1-WATANA RESERVC
OPERATION OF THE WATANA I DEVIL CANYC
r-------------------------------------------------
,J i-004 I 065 I,_, I'JS7 ,.,....-I-=-')I)=-='),.-J--.,1..,-J=7o-"
MONTHLY ENERGY
-
-
'jl J]_ l 1f ~ ill ;.. 1,_ ~ r (I
'
-fl.J ~ u 1-rt--.. J 1 rt-~j
_j
1376 I ')7~~
---·--------·--~-· --
~ 1 11 ~
_1. ~ \ It: l A I
fl,
[1._ u IL-u ~J u u t~
' " . '' ' ' ' r:: 1364 196~ !91)6 !967 ,)SS 1969 1)70 l~Fl 1972 19!3 1974 197~ 1976 1'377 1378 1979
. I~ MONTHLY IN FLOW
MONTHLY DISCHARGE
-I rMAXU UM EL VATION
,...,.J \J \i 1\ I 1\J \f ~ . .rl ~~ f \{ 1\ I ~ ) \ r \f i\f 1\J ' ~
r' ~lJ "lJ 1J lJ LJ v \ f \ \J \J v \J 1J '1J ..... 'lJ
1j \
tM INIMU~ ELEVA frlON
r:: . " ' ' . >3 19154 196:> 1966 1967 1968 1969 1·FO ,97, 1972 1973 1974 197~ 197? 1977 1976 1979
"""\10NTHLY ELEVATION
ANA RESERVOIR (400 MW)
r DEVIL CANYON DEVELOPMENT PLAN E J .3 · FIGURE 9.3~~~~
-0
.~ 19~ 1 I 9~2 19~:3 I 954 I 9~5 I ')':i" I ')~7 1 958 I 9 I %0-i 9~ I 1963 i1l64 I ')i;r!)
AVERAGE MONTHLY E~
------------···-· -------r----
--i--------·--
~ n n ~ 1 n 1 n 1 Jl
)l J~ ~t, r l ~ J J J 1 l
,_j n-J ~ r-1 -J J k k u ~ ~ lL 1._ \_ li ~ .-: ..,.., ~-C" "' 0' . r 13:~0 1951 19"'" 19J3 19.>4 195;:> 19J5 r957 1958 1959 1960 1961 1962 1963 1964 196,
AVERAGE MONTHLY I
r· -----·-... _
1
.! _('" ~ n I J n
~ ~ f""') ~~ ~ ~ ~ M...J ll"'1...jl ~ ~ ~ ~ rJ lr'l.J I rt....
.,. •. r . "' rr. .,. ' .. • <" ,., ' '
AVERAGE MONTHLY [
~ MAXIM M ELE' ~TION
v \J \J \i \) \J v \) lJ \) v \f \ \f \ \
1950 i951 1352 1?53 i954 1355 1956 1957 1958 1959 1960 1961 1962 1963 1964 i9E
AVERAGE MONTHLY
NOTE : WATER YEt\R OCT.-SEPT.
STAGE 3-WATANA RESER'
OPERATION OF THE WATANA/ DEVIL CAN
~3 1954 I ')65 19!lfi I ')!')7 I ')68 I 969 I ')70 1971
MONTHLY ENERGY
----.--·---·~ --.--·-------f-· . -
-
Jl .I1 ~ rJ ~ ~"-IU ~
~ I~ lls,
r1 j1 I 'llj r'l 1 p I
I I
~il3 LJ ~J l_, L [L_ J 1
11.. h. j ~j ~ r,_ J it.. tLJ ~] LJ lJ ,..,__
1964 1965 1966 1957 1968 I 9?') 197'0 i 97'1 1972 J'J73 1974 I ~)75 1')71) I 97'7 197S 1979
.~E MONTHLY INFLOW -, ---~·---···-·-. ----·---.-----.--
LS
963 1964 1965 1966 1967 1968 1969 J§~o
. MONTHLY DISCHARGE
-
'J63 1964 1965 1966 1967 1968 1969 1970
GE MONTHLY ELEVATION
""""
~TANA RESERVOIR ( 800 MW)
"l DEVIL CANYON OEVELDPMENT PLAN E 1.3
1372 1973 i974 1975 1971) 1977 137i 19 9
~n. J ~ I~ 1~ lt\ l~ f ~ I~ J
J \1 \J v \ ( \) \j 1J \)
u [
i 97 I 972 I 97 3 i 97 4 1975 1971) 1977 1976 1979
FIGURE 9.4 [ill
-
....
0
0
M
(./)
l.L ug -.
30 oo __ J -
LL z
-
-.----
-.
r', ... -.., t; ·,
. .
--
I
( r ! Nu ~~ rJu lr'v ~
AVERAGE MONTHLY E
f-----~---· ----
·+·---·-r-· ·-
,r .J
I
r r f
~~ ('\r P\f ~""'"\;J ~~ ~~ r'\t r'\J N
·" '"' ' ~ ?-,r:: • ' c I :t C:: . ,-• • ~M . ' "' . '' I .... ' o 19"'0 19;JI 19"' ... 19:.>3 ,::b4 1::1"':.> 1h6 ,9;:,7 19;>o !)"':) 1:)60 196, 195.:: 19153 1)64 1'31).
M
0
-o . ,.,
en
0
'It
lJ...
Uo ._. (.")
w· (_')~
Q::
< ::c
Uo cno
~ lt""'\...-..1
I I
r"'1...JU' rvu ~ ~ V'"'lJ'
AVERAf.iE MONTHLY I
I I I .II
~ ~ fM.fU ~ ~ r7i'Q rv-r"'"'l,j "'""1....
" .,. c .., .. " "' r ~ 0 19;:,0 19Jl 19;:,2 19;:,3 19;J4 19J5 19J6 19J7 1956 1959 1960 1961 1962 1963 1964 196
Cl
0
0 .
..... ~
I-'¢
l.L~
z og
~.
1-0
<(~
>~
UJ
_JO
wC:
0
;()
"' "" ~ 19 .... 0 1951 1'352 1953 1954 1355 19~6
NOTE: WATER YEAR OCT.-SEPT.
1'\ .......
AVERAGE MONTHLY C
IT
r:'""' 19 .... , 1956 1959 1960 1961 1962 1963 1964 196
AVERAGE MONTHLY I
STAGE 3-DEVIL CANYON F
OPERATION OF THE WATANA/DEVIL CJ
_.MONTHLY ENERGY
-·--·-,.............----
~
-. -,. ' r -J
J J
--···-
.... r· I r'1 n , n
l r~ N ~u ~v N ~~ fl'\!'1 {"\jlfl ~'\J ~ /;.Jl"t ~~ ~ ... l'1 ~Jl ~"'tJ~ II'~ ,.~
"""
' ' .,. . ' . ' -,. ·~ -...
,..... MONTHLY INFLOW
~SPit LS
.I J IT ~RBINE
] . ..II " i -
~ r'lJ' ~ ..... ~ V""V ~ ~v-·v r'lJI.! ~ ,...,.,_ ~ ~ /'"'l.tU ~ ~
,.&..1 1964 1965 1966 1967 1968 1969 19'70 1971 1'372 1'37'3 1974 1975 1975 1977 !976 1979
MONTHLY DISCHARGE
rMAXIMUM EL VATIO~
t
-.. i 1964 196~ 1966 1967 1968 1969
~ MONTHLY ELEVATION
~CANYON RESERVOIR (400 MW)
J I )
I J
1 MINIMUM ELEVA ION
r: 1972 I '.F3 1974 197:> 1976 1977 1978 1979
jOEVIL CANYON DEVELOPMENT PLAN E 1.3 FIGUR€ 9.5.
-
-'
-
(I) u..
(.)
I
UJ
<!) a::
~ :c:
ul <n
0
~
;:)
~ x
<(
~
2
9
6
2 5 10 25 50
RETURN PERIOD 1 YEARS
DISCHARGE-STAGE FREQUENCY CURVE
SUSITNA RIVER AT GOLD CREEK
NOTE: BASED ON PRELIMINARY DATA,
SUBJECT TO REVISION 9-23
1-
UJ
UJ u.
I
1-
:J:
~
liJ
J:
UJ
C.!).
~
<!)
FIGURE 9.JiJ
r
-
-
en u.
(,)
I
UJ
<!:) a:
<C
J:
6 10
9
5
4
3
2
5 ~ 10 a 9
2 8 ::a :e 7 x
<t 6 :e
5
4
3
2
2 5 10 25 50
RETURN PERIOD, YEARS
DISCHARGE-STAGE FREQUENCY CURVE
SUSITNA RIVER AT SUSITNA STATION
NOTE: BASED ON PRELIMARY DATA,
SUBJECT TO REVISION 9-24
UJ
<!)
<(
t!)
FIGURE 9JIIII
r-
""""
~·
-
•l~
,....
, ...
.~-
7
6
5
4
3
2
Cl) u..
(.)
I
UJ
(,!)
1%
~ :::r: ~~as s 9
~ 8
::)
~ 7 x
<t 6
~
5
4
3
2 5 10 25 50
RETURN PERIOD, YEARS
01 SCHARGE -STAGE FREQUENCY CURVE
SUSITNA RIVER AT SUNSHINE
9-25
NOTE: BASED ON PREI.IMINARY DATA
SUBJECT TO RETURN
....
-
I
I
\ ~ ! \ -. ~\
9-26
GENEQA.L
' )
I
,~
\
\
AAQA.NGEME.NT
) , .....
-
I..OC-"t..IZEO
CDNC~&.TE I.INING
so'
A· A
...:=
F""" I,...,
I ::~!X>
It=
-
CROWt-.1 SECTION
-
SECTION Ti-IRU POWER FAClL.ITIES
9-27
1!1«1
W/10
~
1~00 --------------·--. .-----
1100
·-1----------------------
"""
lao ----
100 L
111!11:1 1---------------------
'>
ACe
I~ L-------------·------,-----~(~~-
1000
100 ~--------
eao ,_ ___ _
5EC:
-.TWL. El...890
.....
-
....
....
' ;II.
.wt. ~L OPIIR,IqiWG
llltL EL. 1450'
----~:-.:-;-·
I
.-.L SU~FACE.
'SIDE) -----
DAM PROFILE. (.LOOKING UPSTI<.£AM)
SECTIOt-.1 THRU SPILLWA.Y
.. ,. -
011/E.RsiON TIJNNE\.$
II
AlASKA POWER AUTHORITY
DEVIL CANYON
SCHEME I
SECTJO-
~-.1--
GENERAL ARRANGE~
/
GENERAL ARRANGEMENT
WATANA
SCHEME :t
:'""
-
-
-
-
-
~
~
-
r-
r-
'l:t~
'l~
2.1!.0
'ZIOO
20SO
:00:0
l!:t50
19100
11!!:10
~ac:ot
IT~
1700
IC.OO
1~50
... c
rOIO!IGIN4L. G~OWO
• WI2FA.C.!!. • s:tl(i"T 510~ ··-------------r-----...::------~ ·-----... -....... ----... ---...
~c
SPIL[WAY PROF ICE
SCAl-E.: A ----ORIGI~ Gc<O~-~--· ___..
SECTION D-O
SCl>.l..I!.<A
I&OOr--------------------------------------------------------------
1400~----------------------------------------------------------------------
'2.'2.'50 --2.':l00
'1150
J .---
I~ '2'200
2150
'2.100 2100 I
--~
16!>0
1800
.--
~
5U
.....-
1.....-
L... I
SECTION A-A SECTION 8-B
SGAUI.' A '.loCAL.£ ' A
9-29 ,
~----------------------------------~----
--o·-= ... '<•-...__ -------------. ---...._ ----
ION 0-0 ..... , ...
1800
SECTION E-E
' ' ...... _ .........
"' ~ c!:11:;AVATE. AU..l.IVIUM ,_... -....:: --=:::::;-IN RIVE'Z e>W . ....... ------'·· ' ".. --------.... ............. ........
·~ ~" ~~·
) r--.-r--
I~ ...___ ...___ ~~
·-·-I
L,
SECTION B-8
$GAL£: A.
$CAl-E.: A
........
TYPICAL CHUTE WALL SECTION
SG ... LE: e
SECTION C·C
~:A.
-
PLATE 13
ALASKA POWER AUJIIORITY
--------
WATANA
SCHEME 2
3£CTIONS
CII. ,., 1/W . .-a.---......... --
"""' '
-
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 deve 1 opment 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) Rail be 1 t System annual energy requirement is estimated
to be 2790 Gwh and the peak demand 515 MW. 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 i ntert i e 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
!"""
I
....
-
{g)
(h)
• Ten additional potential hydroelectric developments located outside the
Susitna Basin and ranging from 8 to 480 MW in capacity and 33 to 1925
Gwh annua1 energy yield.
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 l·Iti es wi 11 be
restricted to peak load application only.
The Susitna Basin development selection studies indicated that the 1200 MW
Watana-Devil 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 develops 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 not compatible with the
Watana-Devil Canyon development plan as the site wou1d be inundated by the
Devil Canyon development.
(i) Comparison of the Railbe1t system generation scenario incorporating the
Watana-Devil Canyon Susitna development and the all thermal option reveals
that the scenario 11 With Su sitna11 is economi ca 11y 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 11 With Susitna 11 scenario is the preferred option.
The 11 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 zer1, ~he all thermal generating scenario becomes more econom-
ic. However, it is not likely that such high interest rates or low fuel
escalation rates would prevail during th~ foreseeable future.
(j) Economic comparisons of the generating scenarios 11 With Susitna 11 and the
scenario incorporating alternative hydro options indicate that the present
worth cost of the "with Susitna 11 scenario is $1190 million less.
(k) Preliminary engineering studies indicate that the preferred dam type at
Watana is a rockfill alternative while a double curvature thin arch con-
crete dam is the most appropriate type for the Devil Canyon site.
10.2 -Recommendations
The recommendations outlined in this section pertain to the continuing studies
under Task 6 Design 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 ~ontinue on the selected Susitna
Basin Watana-Devil Canyon deve1opment plan. These studies should encompass the
following:
10-2
-
·-
-
(a) Project Planning
Addi-tional optimization studies should be conducted to define in more
detail, the Watana-Devil 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 Devi 1 Canyon powerhouse closer to
Portage Creek in order to make use of the additional head estimated to
amount to 55 feet.
-Reservoir operating rule cw·ves
-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 feasibility 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 ~tudies.
(b) Project Engineering Studies
(c)
The engineering studies outlined in Subtasks 6.07 through 6.31 should con-
tinue as originally planned in order to finalize the project general
arrangements and details, and to firm up technical feasibility of the pro-
posed development.
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 a~J the
Railbelt generation alLernatives study is completed. The object1ve of
these studies should be to refine the assessment of the ecanomic, environ-
mental, and social feasibility of the proposed Susitna Basin development.
10-3
-
.....
-
-
-
-
--
-
TABLE 10.1 -ENERGY AND CAPACITY FORECASTS FOR 201~
Load Growth
Very low (i.e. incorporating additional
load management and conservation
measures)
Low
Medium
.hgh
10-4
Project Annual t.nergy Demand
Gwh
5,2011
6,22fJ
8,940
15,930
Eauivalent
Annual Rate
of Increase
2. 1~
2. 7%
4.fl%
6.~
Peak
Demand
NW
9111
1 • 14!1
1,635
2.9011
-
BIBLIOGRAPHY
(In Preparation)
-
-
-
-
-I
'
-
-
APPENDIX A
GENERIC PLAN FORMULATION AND
SELECTION METHODOLOGY
·-
-
APPENDIX A -GENERIC PLAN FORMULATION AND
SELECTION METHODOLOGY
On numerous occasions during the feasibility stu1ies for the Susitna Hydro-
electric Project, it is necessary to make decisions in which a single or a small
number of courses of action are selected from a larger number of possible alter-
natives.
This appendix presents a generalized framework for this decision making process
that has been developed for the Susitna planning studies. It outlines, in gen-
eral terms, the approach to be used in screening a large multitude of options
and finally establishing the best option or plan. It is comprehensive in that
it takes into account not just economic aspects but also a broad range of envir-
onmental and social factor5.
The application of this generalized methodology is particularly relevant to the
following decisions to be made during the Susitna studies:
-Selection of alternative plans involving thermal and/or non-Susitna hydro-
electric developments in the primary assessment of the economic feasibility of
the Susitna Basin development plan (Task 6).
-Selection of the preferred Susitna Basin hydroelectric development plan (i.e.
identification of best combination of dam sites to be developed) (Task 6).
-Selection of the preferred Railbelt generation expansion plan (i.e. comparison
of Railbelt plans with and without Susitna).
-Optimization of the selected Susitna Basin development plan (i.e. deter·mining
the best dam heights, installed capacities, and staging sequences) (Task 6).
i -Selection of the preferred transmission line routes (Task 8).
-
-Selection of the preferred mode of access and access routes (Task 2).
-Selection of the preferred location and size of construction and operational
camp facilities (Task 2).
It is recognized that the above planning activities embrace a very diverse set
of decision making processes. The generalized methodology outlined here has
been carefully developed to be flexible and readily adaptable to a range of ob-
jectives and data availability associated with each decision.
The following sections briefly outline the overall decision making process and
discuss the guidelines to be used for establishing screening and evaluation
criteria.
A-1
......
-
-
....
-
-
f""'
I
A.l -Plan Formulation and Selection Methodology
The methodology to be used in the decision process can generally be subdivided
into five basic steps (Figure A.l):
-Step 1: Determine basic objectives of planned course of action
-Step 2: Identify all feasible candidate courses of action
-Step 3: Establish basis to be used and perform screening of candidates
-Step 4: Formulate plans incorporating preferred alternatives
-Step 5: Re-establish basis to be used, evaluate plans and select preferred
plan
Under Step 2, the candidate courses of action are identified such that they sat-
isfy, either individually or in combinations, the stated objectives {Table Al).
In Step 3, the basis of screening these candidates is established in items of
redefined, specific objectives, assumptions, data base, criteria and methodol-
ogy. This process follows a sub-series of 7 steps as shown in Table A.2 to pro-
duce a short list, ideallv of no more than 5 or 6 preferred alternatives. Plans
are then formulated in Step 4 to incorporate single alternatives or appropriate
combinations of alternatives. These plans are then evaluated in Step 5, using a
further redefined set of objectives, criteria and methodology, to arrive at a
selected plan. This 6-step procedure is illustrated in Table A.3. Tables A.2
and A.3 also indicate the review process that must accompany the planning pro-
cess.
It is important that within the plan formulation and selection methodology, the
objectives of each phase of the decision process be redefined as necessary. At
the outset the objectives will be br~ad and somewhat general in nature. As the
proctss continues, there will be at least two redefinitions of objectives. The
first will take place during Step 3 and the second during· Step E. As an exam-
ple, the basic objectives at Step 1 might be the development and application of
an appropriate procedure for selection of a single preferral course of action.
Step 2 might involve the selection of those candidates which are technically
feasible on the basis of a defined data base and set of assumptions. The objec-
tives at Step 3 might be the establishment and application of a defined set of
criteria for elimination of those candidates which are less acceptable from an
economical and environmental standpoint. This would be accomplished on the
basis of appropriately modified data case and assumptions. Having developed
under Step 4, a serie~ of plans incorporating the remaining or preferred alter-
natives, the objectives under Step 5 might be the selection of the single alter-
native which best satisfies an appropr;ately redefined set of criteria for· say
economic, environmental and social acceptability .
A.2 -Guidelines for Establishing Screening and Evaiuation Criteria
Definition of criteria for the screening and evaluation procedures will largely
depend on the precise nature of the alternatives under consideration. However
in most cases, comparisons will be based on technical, economic, environmental
and socioeconomic factors which will usually involve some degree of trade-off in
A-2
-
-
-
·-
making a preferred selection. It is usually not possible to adequately quantify
such trade-offs.
Additional criteria may also be separately considered in some cases, such as
safety or conservation of natural resources. Guidelines for consideration of
the more common overall factors are discussed in the following paragraphs.
(a)
(b)
Technical Feasibilitx
Basically all options considered must be technically feasible, complete
within themselves, and ensure public safety. They must be adequatel:' de-
signed to cope with all possible conditions including flood flows, sL.smic
events, and all other types of normal loading conditions.
Economic Criteria
In cases where a specific economic objective can be met by various alterna-
tive plans, the criteria to be used is the least present worth cost. For
example, this would apply to the evaluation of the various Railbelt power
generation scenarios, optimizing Susitna Basin hydroelectric developments,
and selection of the best transmission and access routes. In cases where
screening of a large number of options is to be carried out, unit commodity
costs can be usea as a basis of comparison. For instance, energy cost in
say $/kwh would apply to screening a number of hydroelectric development
sites distributed throughout southern Alaska. Similarily, the screening of
alternative access or transmission line route segments would be based on a
$/mile comparison.
As the Susitna Basin development is a State project, economic parameters
are to be used for all analyses. This implies the use of real (inflation
adjusted) interest rat~s and only the differential escalation rates above
or below the rate of general price inflation. Intra-state transfer pay-
ments such as taxes and subsidies are excluded, and opportunity values {or
shadow prices) are used to establish parameters such as fuel and transpor-
tation costs.
Extensive use should also be made of sensitivity analyses to ensure that
the conclusions based on economics are valid for a range of the values of
parameters used. For example, some of the more common parameters consid-
ered ~n comparisons of alternative generation plans, particularly lend
themsHlves to sensitivity analyses. These may include:
-Load forecasts
-Fuel costs
-Fuel cost escalation rates
-Interest and discount rates
Economic life of system components
-Capital cost of system components
A-3
1--
-
-
-
-
(c) Environmental Criteria
(d)
Environmental criteria to be considered in comparisons of alternatives are
based on the FERC ( ) requirements for the preparation of the Exhibit E
"Environmental Report" to be submitted as part of the license application
for the project. These criteria include project impacts on:
Physical resources, air, water and land
-Biological resources, flora, fauna and their associated habitats
Historical and cultural resources
-Land use and aesthetic values
In addition to the above criteria which are used for comparing or ranking
alternatives, the following economic aspects should also be incorporated in
the basic alternatives being studied:
-In developing the alternative concepts or plans, measures should be in-
corporated to minimize or preclude the possibility of undesirable and
irreversible changes to the natural environment.
-Efforts should also be made to incorporate measures which enhance the
quality aspects of water, land and air.
Care should be taken when incorporated the above aspects in the alterna-
tives being screened or evaluated to ensure consistency between alterna-
tives, i.e. that all alternatives incorporate the same degree of mitiga-
tion. As an example, these measures could include reservoir operational
constraints to minimize environmental impact, incorporation of air quality
control measures for thermal generating stations, and adoption of access
road and transmission line design standards and construction techniques
which minimize impact on terrestrial and aquatic habitat.
Socioeconomic Criteria
Similarly, based generally on FERC requirements, the project impact assess-
ment should be considered in terms of socioeconomic criteria which
include:
-Impact on local corrununities and the availability of public facilities and
services
-Impact of Pmplo)fllent on tax and property values
-Displacement of people, businesses and farms
-Disruption of desirable community and regional growth
A-4
-
-
A.3 -Plan Selection Procedure
As noted above, for each successive screening exercise~ the criteria can be re-
fined or modified in order to reduce or increase the number of alternatives
being considered. As a general rule, no attempt will be made to ascr·ibe numeri-
cal values to non-quantifiable attributes such as environmental and social im-
pacts, in order to arrive at an overall numerical evaluation. It is considered
that such a process tends to mask the judgemental tradeoffs that are made in
arriving at the best plan. The adopted approach involves utilizing combinations
of both quantifiable and qualitative parameters in the screening exercise with-
out making tradeoffs. For example, the screening criteria used might be:
-...... alternatives will be excluded from further consideration if their unit
costs exceed X and/or if they are judged to have a severe impact on wildlife
habit at .... n
This approac~ is preferable to criteria which might state:
-...... alternatives will be excluded if the sum of their unit cost index plus
the environmental impact index exceeds Y ......
Nevertheless, it is recognized that under certain circumstances, particularly
where a relatively large number of very diverse alternatives must be screened
very quickly, the latter quantitative approach may have to be used.
In the final plan evaluation stages~ care will be taken to ensure that all
tradeoffs that have to be made between the different quantitative and qualita-
F"" tive parameters used, are clearly highlighted. This will facilitate a rupid
focus on the key aspects in the decision making process.
An example of such an evaluation result might be:
11 •••• Plan A is superior to Plan B. It is $X more economic and this benefit
~ is judged to outweigh the lower environmental impact associated with Plan B
II
Sufficient detailed information should be presented to allow a reviewer to make
an independent assessment of the judgemental tradeoffs made.
The application of this procedure in the evaluation stage is facilitated by per-
forming the evaluations for paired alternatives only. For example, if the
shortlist plans are A, B, and C then in the evaluation Plan A is first evaluated
against Plan B, then the better of these two is evaluated against C to select
the best overall plan.
A-5
-
,~
-
-
-
-
TABLE A.1 -STEP 2-SELECT CANDIDATES
Step 2.1 -Identification of candidates:
-objectives
-assumptions
-data base
-selection criteria
-selection methodology
Step 2.2 -List and describe candidates that will be used in Step 3.
TABLE A.2 -STEP 3 -SCREENING PROCESS
Step 3.1 -Establish:
-objectives
-assumptions
-data base
-screening criteria
-screening methodology
Step 3.2-Screen candidates, using methodology established in Step 3.1 to
conduct screening of alternatives.
Step 3.3 -Identify any remaining individual alternatives (or combinations of
alternatives) that satisfy the objectives and meet the criteria
established in Step 3.1 under the assumptions made.
Step 3.4 -Determine whether a sufficient number of alternatives remain to
formulate a limited number of plans. If not, additional screening
via Steps 3.1 through 3.3 is required.
Step 3.5 -Prepare interim report.
Step 3.6 Review screening process via (as appropriate):
-Acres
-APA
-External groups
Step 3.7 -Revise interim report.
A-6
-
-
·-
-
TABLE A.3 -STEP 5 -PLAN EVALUATION AND SELECTION
Step 5.1 -Establish:
-objectives
-evaluation criteria
-evaluation methodology
Step 5.2 -Establish data requirements and d~·velop data base.
Step 5.3 -Proceed with the plan evaluation and selection process as follows:
-Identify plan modifications to improve alternative plans
-Based on the established data base and the selection criteria, use
a paired comparison technique to rank the plans as ( 1) the preferr-
ed plan, (2) the second best plan, and (3) other plans;
-Identify tradeoffs and assumptions made in ranking the plans.
Step 5.4 -Prepare draft plan selection report.
Step 5.5 -Review plan selection process via (as appropriate):
-Acres
-APA
-Exte·mal groups
Step 5.6 -Prepare final plan selection report.
A-7
] 1
Activity
Susitna Basin
Development
Selection
Access Route
Selection
TABLE A.4 -EXAMPLES Of PlAN fORMULATION AND SELECTION METHODOLOGY
1. Define
Objectives
Select best
Susitna Basin
hydropower
development
plan
Se.lect best
access route
to the pro-
posed hydro-
power develop-
ment sites
within the
basin for
purposes of
construction
and operation
2. Select
Alternatives
All alternative
dam sites in the
basin, e.g.:
Devil Canyon;
High Devil Canyon;
Watana
Susitna II I;
Vee;
Maclaren;
Butte Creek;
Tyone;
Denali;
Gold Creek;
Olson;
Devil Creek;
Tunnel Alternative
All alternative
road, rail, and
air transport
component links,
e.g.:
road and rail
links from Gold
Creek to sites
via north and
sotJth routes;
Road links to
sites from Denali
Highway;
Air links to
3. Screen
Screen out sites
\'klich are too
small or are
known to have
severe environ-
rental impacts
Screen out links
~ich are either
100 re costly or
have hi~er
environmental
impact than
equivalent
alternatives.
Ensure suffi-
cient links
remain to allow
formulation of
plans
sites and associated
landing facilities
4. Plan
formulation
Select several
combinations of
dams ~ich have
the potential
for delivering
the lowest cost
energy in the
basin, e.g.:
Watana-Devi 1
Canyon dams;
High Devil
Canyon-Vee dams;
Watana Dam -
Tunnel
Select several
different access
plans, e.g.:
Gold Creek road
access;
Gold Creek road/
rai 1 access;
Denali Highway
road access
I
5. Evaluation
Conduct detailed
evaluation of
development plans
Conduct detailed
evaluation of
development plans
:Po
I
\0
] -I
[~_ ··-•.. ------------~----~---------------------------
-~--·-··-·····--------.
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 A.l [iii