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SUSITNA HYDROELECTRIC PROJECT
FEASIBILITY REPORT
VOLUME 1
ENGINEERING AND
ECONOMIC ASPECTS
SECTIONS 1-8
FINAL DRAFT
ARLIS
Alaska Resources
~~~~ ~ ~mormation Services
·· · ~9\l,Qf,age Alaska
L------ALASKA POWER AUTHORITY __ ____J
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SUSITNA HYDROELECTRIC PROJECT
FEASIBILITY REPO~T
VOLUME 1 -ENGINEERING AND ECONUMIC ASPECTS
1 -INTRODUCTION ................................................. .
1.1 -Introduction ......................................... .
1.2 -Project Description .................................. .
1.3 -Objectives and Scope of Current Studies .............. .
1.4 -Plan Formulation Selection Process ................... .
1.5 -Organization of Report ............................... .
1.6 -Principal Project Parameters ......................... .
2 -s LIIYIM AR y . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.1 -Scope of Work ........................................ .
2.2 -Previous Studies ..................................... .
2.3 -Railbelt Load Forecasts .............................. .
2.4 -Railbelt System and Future Power Generation Options ... .
2.5 -Susitna Basin ........................................ .
2.6 -Susitna Hasin Development Selection .................. .
2.7 -Susitna Hydroelectric Development .................... .
2.8 -Watana Development ................................... .
2.9 -Devil Canyon Development ............................. .
2.10-Transmission Facilities .............................. .
2.11 -Construction Cost Estimates and Schedules ............ .
2.U Environmental Impacts and fl'litigation 1v1easures ........ .
2.13 -Project Operation .................................... .
2.14-Economic and Financial Evaluation .................... .
2.15 -Conclusions and Recommendations ...................... .
3 -SCOPt UF WORK ............................................... .
3.1 -Evolution of Plan of Study ....•.......................
3.2 -Task 1: Power Studies ............................... .
3.3 -Task 2: Surveys and Site Facilities ................. .
3. 4 -Task 3: Hydro 1 ogy ................................... .
3.5 -Task 4: Seismic Studies ............................. .
3.6 -Task 5: Geotechnical Exploration .................... .
3.7 -Task 6: Design Development .......................... .
3.8 -Task 7: Environmental Studies ....................... .
3.9 -Task 8: Transmission ................................ .
3.10-Task 9: Construction Cost Estimates and Schedules ... .
3 .11 -Task 1 0: L i c ens i n g •...................................
3.12-Task 11: Marketing and Financing ..................... .
3.13 Task 12: Public Participation Program ................ .
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3-12
3-13
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3-16
3-17
3-18
VOLUME 1 -ENGINEERING AND ECONOMIC ASPECTS (Cont'd)
PAGE
4 -PREVIOUS STUDIES •..•..•..•....•.....••.•..•.•.•.•.........•.. 4-1
4.1 -Early Studies of Hydroelectric Potential ............... 4-1
4.2 U.S. Bureau of Reel arnat ion -1953 Study................ 4-2
4.3 U.S. Bureau of Reclamation-1961 Study •.•...•.•.••..• 4-2
4.4 Alaska Power Administration-1974 .••••...•..••.••.•.. 4-2
4.5 Kaiser Proposal for Development ..•..•.•.........•.•••.. 4-3
4.6 U.S. Army Corps of Engineers-1977 & 1979 Studies .••.•.. 4-3
5 -RAILBELT LOAD FORECASTS .....•••...••••..............••....•..• 5-1
6
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5.1 -Scope of Studies ......•.....••••.....••••.•••.....•...• 5-1
5.2 -Electricity Demand Profiles .•..••..•...••.•.•......••.• 5-1
5.3 -Battelle Load Forecasts ..••...•..•...•.....•..•..••••. 5-5
-RAILBELT SYSTEM AND FUTURE POWER GENERATION OPTIONS .••..•....•
6.1 -Basis of Study .....••..•.•.•....•.•..•..••...•.......•
6.2 -Existing System Characteristics ......•.....•........•..
6.3 -Fairbanks -Anchorage Intertie .•.•......•.....•..•...
6.4 -Hydroelectric Options ......••.•......•.....•.....•.•...
6.5 -Thermal Options -Development Selection •..•......•.••..
6.6 -Without Susitna Plan ••........•.•......•.........•..•.
-SUS ITNA BAS IN ....•...•....••..•...•....•...•.............•.•.
7.1 -Cl ·imatology ................••........•..•......•......
7.2 -Hydrology .......•...•........•..•..•......•.••....•..•
7.3 -Regional Geology ......•....••...........•..••..•.••...
7.4 -Seismicity ..•.....•..•......••..•..•...•..•......•....
7.5 -Water Use and Quality ....••.......................•..•
7.6 -Fisheries Resources ...............•....•••...•......••
7.7 -Wildlife Resources .....•...••...•........•..•..•.....•
7.8 -Botanical Resources ..•..........••..•............•.•..
7.9 -Historic and Archaeological Resources •....•..•.....•...
7.10 -Socioeconomics .•..•...•....•........•......•.....•....
7.11 -Recreational Resources ••...••.•.....••....••.......••..
7.12 -Aesthetic Resources ......•..•...........•...••...••..•
7.13-Land Use .......•..•..........•..•..•............•.....
-SUSITNA BASIN DEVELOPMENT SELECTION .•....•............•.....••
8.1 -Plan Formulation and Selection Methodology ••..•......•.
8.2 -Damsite Selection ...•.••..•....•..•......•..••.••.•..•
8.3 -Site Screening ..•.••.•.....••.•..•..•...•.....•..•....
8.4 -Engineering Layouts .••.•.....•.....•...•.•............
8 . 5 -Cap i tal Co s t ••...•...•......•.•..•.............•.•..•.
8.6 -Formulation of Susitna Basin Development Plans .....•.•
8.7 -Evaluation of Basin Development Plans ...••..•..•.•..••
8.8 -Preferred Susitna Basin Development Plan ••....•.••.••..
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6-2
6-4
6-4
6-6
6-11
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7-21
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7-23
7-23
7-25
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8-2
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8-3
8-7
8-7
8-10
8-17
Note: Sections 9 to 19 are bound under separate cover.
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VOLUME 1 -ENGINEERING AND ECONOMIC ASPECTS (Cont'd)
9 -SELECTION OF WATANA GENERAL ARRANGEMENT •••••••••.•.•••.•••.••
9.1 -Site Topography ••••••..••.•.••.••.••••••••••••••.••••.
9.2 -Site Geology •••••••••••••••••.•.••••••••••••••••••••••
9.3 -Geotechnical Design Considerations ••.•••.•••.•••.•••••
9.4 -Seismic Considerations ••••.•.••.••.••.••.••.••••••••.••
9.5 Selection of Reservoir Levels ••.••••••••.••••••••••.••
9.6 Selection of Installed Capacity •••••••••••••.••••••••••
9.7 -Selection of the Spillway Design Flood .•.••.•.••.••••••
9.8 Main Dam Alternatives •••••.•••••••••••••••.•••••••••••
9.9 -Diversion Scheme Alternatives ••••••.•••.•••••••••.•••••
9.10-Spillway Facilities Alternatives ••••••••••.••••••••••.
9.11 -Power Facilities Alternative ••••••••••••••••••••••••••
9.12 -Selection of Watana General Arrangement •••••••.•••••••
9.13-Preliminary Review •••••••••••••••••••••••••.••.••••••.•
9.14-Intermediate Review •.•.••••.••••.••••••••••••••••••••••
9.15 -Final Review .•••.•.•••••••••••••••••••••••••••••••••••
10 -SELECTION OF DEVIL CANYON GENERAL ARRANGEMENT ••.•••••••••••.••
10.1 Site Topography •••.•••••••••••.•.•••••••••••••••••••••
10.2 -Site Geology ••••••••••••••••.•••.••••••••••••••••.••••
10.3 -Geotechnical Considerations .•.••••.•••••••••••••••••••
10.4 Seismic Considerations .•.•••••..••••••••••••••••••••••
10.5 -Selection of Reservoir Level ••••.••.•••••••••••••••••••
10.6 -Selection of Installed Capacity •••.•••.•••••••••••••••
10.7 -Selection of Spillway Capacity .•••••••••••••••••••.••••
10.8 -Main Dam Alternatives .••••••••.•••••••••••••••••••••••
10.9 Diversion Scheme Alternatives •••••••••••••.••••••••.••
10.10 -Spillway Alternatives •••••••••••••••••••••••••••••••••
10.11 -Power Facilities Alternatives •••••••••••••••••••••••••
10.12 -Genera 1 Arrangement Se 1 ect ion ••••••.••••••••••••••••••
10.13-Preliminary Review •••.••••••••...••.••••••.•••••••••••
10.14-Final Review .••.••••••••••••••••••.•••••••.••••.••••••
11 -SELECTION OF ACCESS PLAN ················~····················
11.1 -Hackground ••••••••.••••••••••••••••••••.••••••••••••••
11. 2 0 b j ec t i v e s ••••••••••••••••••••••••••••••.•••••••••••••
11.3 -Approach ••••••••••••••••••••••.•••••••••••••••••••••••
11.4 -Corridor Selection and Evaluation ••••••••••••••••••••••
11.5 -Route Selection and Evaluation •••••••••••.••••••••••••
11.6 -Description of Basic Plans •••••••••.••••••••••.•••••••
11.7-Additional Plans •••.••••••••••••••••••••••••••••••••••
ll.8-Evaluation Criteria ••.•••••••••••••••.••••••••••••••••
11. 9 - E v a 1 u at i on of Ac c e s s P 1 an s • • • • • • • • • • • • • • • • • • • • • • • .••••
11.10-Identification of Conflicts ..•••••••••••••••••••••••••
11.11-Comparison of Access Plans ••••••••••••••••••••••••••••
11.12-Recommended Access Plan ••••••••••••••••••••••••••••••••
PAGE
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VOLUME 1 -ENGINEERING AND ECONOMIC ASPECTS (Cont•d)
12-WATANA DEVELOPMENT •..•••..•.....•....•••••.•.••.•••.•.••..•••
12.1 -General Arrangement .•....•..••..•..••.•.•••.•..•••...•
12 . 2 - S i t e Access ••..•••••••••..•••.••••.•.•••.•••.•...•••••
12.3-Site Facilities •.••••••••..••••..••••••..•••••.••.••••
12.4-Diversion •••.•...•••••..•.•...•••..•.••.••..••••..•..•
12.5-Emergency Release Facilities •..••.......••...••..••.•••
12.6 -Comparison with Precedent Structures •..•••.•.•..••••.••
12.7-Relict Channel Treatment •.•.••.•.•.••.•••.•.•..•.••••••
12.8-Outlet Facilities •..•••.•••••.•••••••••.•••••••.•.•.••
12.9-Main Spillway ••.••..•••••••.•.••.•.••.••..•..•••..•..•
12.10-Emergency Spillway •••••.•••..•••.••...•••••.•.•••..••.
12.11-Intake •...••.••...•.••.•••....•••.••••..•..•••••••••..
12.12-Penstocks .•••.••..••..•.•.•••••...•••.••.•.••••.••..••
12.13-Powerhouse •.•.••.••..•.••.•••.••.••••••••••.•.•••••••.
12.14-Reservoir •.•.•.....•••••••..•...•.•••••.•••••.•.••••••
12.15-Tailrace •.•.••••..••••...••••.•.•..••..•.••••...•.•.•.
12.16-Turbines and Generators •....•••.•.••.•.••.•••••..•••.••
12.17-Miscellaneous Mechanical Equipment .•....•..•..•••••.•••
12.18-Accessory Electrical Equipment •.••••••••.••••.•••..•.
12.19-Switchyard Structures and Equipment ••.••.••.••.••..•..•
12.20-Project Lands •••.•••..•.•..••••.••..•••••••...•••••.••
13-DEVIL CANYON DEVELOPMENT .••.•.•.••••..••.•.•••••••.••••••••.•
13.1 -General Arrangement •..••.••..••.•••.••.•..•.•••....•.••
13.2-Site Access .•.••••..••••••..•.•••.•••••.•..••..•.•.•••.
13.3 -Site Facilities ..•••.••••.•••••.••.•.••••.••••••••...••
13.4-Diversion •..•••••••••.••••••••..•..••.•.••••••••...•.•
13. 5 -Arch Dam ....•.••••••••..••.•••..•.•••••••.••..••••....
13.6 -Saddle Dam ••..•...••••.••.•••..••••••...•••.•••.••••••
13.7-Primary Outlet Facilities .•••...•••.•.•••.....•.••.•..•
13.8-Main Spillway ..•••.•••••••••••.••.•.•••.••..•••.•••.••
13.9 -Emergency Spillway •...•.••.••••.•••.•.••.•••••..••...•
13.10-Devil Canyon Power Facilities ••••...•••••••••••••••••••
13.11-Penstocks ••.•••.•.••••.•.••....•.••••.•••••••••..••.••
13.12-Powerhouse and Related Structures ••••.•••••••.•.••.••..
13.13-Reservoir ••••.•••.•.•...•.•••••..•••••••••.••..••••.••
13.14-Tailrace Tunnel •••..••..•••••••.•••.•••••.•••••.••••••
13.15-Turbines and Generators •..•••.•.....••..••..•••..•..•.
13.16-Miscellaneous Mechanical Equipment ••.••..•••••••..•.••
13.17-Accessory Electrical Equipment •••••••••••••.••..•••.•..
13.18-Switchyard Structures and Equipment •.•••.•••...•••••.••
13.19-Project Lands ..•••••••.•••••.•••••••.•••.•••.••.••.••..
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VOLUME 1 -ENGINEERING AND ECONOMIC ASPECTS (Cont•d)
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14-TRANSMISSION FACILITIES •••••••••••••••••••••••••••••.••••••••
14.1 -Electric System Studies ••••••.••••.••••.••••••••••••••
14.2 Corridor Selection ••••••••••••••••••••••••••••••••••••
14.3 Route Selection •••••••••••••••••.••••.••••••••••••••••
14.4 Towers, Foundations and Conductors .••••••••••••••••••••
14.5 Substations •.•.••••••••••••••••••••••••••.••••••••••••
14.6 Dispatch Center and Communications •••••••••••••••••••••
15 -PROJECT OPERATION ••••••••••••••••••••••••.••••••••••••••••••••
15.1
15.2
15.3
15.4
15.5
15.6
15.7
15.8
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Plant and System Operation Requirements ••••••••••••••••
General Power Plant and System Railbelt Criteria •••••••
Economic Operation of Units •••••••••••••••••••••••••••
Unit Operation Reliability Criteria ••••••••••••••••••••
Dispatch Control Centers ••••••••••••••••••••••••••••••
Susitna Project Operation •••.•.••••••••••••••.•••••••••
Performance Monitoring ••••••••••.•••••••••••••••••••••
Plant Operation and Maintenance ••••••.••••••••••••••••
16 -ESTIMATES OF COST ••••••••••••••••••••••••••••••••••••••••••••
16.1 -Construction Costs ••••••••••••..••••••••••••••••••••••
16.2 -Mitigation Costs ••••.••••••••••••••••••••••••••••••••••
16.3 -Operation, Maintenance and Replacement Costs •••••••••.•
16.4 -Engineering and Administration Costs •••••••••••••••••••
16.5-Allowance for Funds Used During Construction •••.••.••••
16.6 -Escalation •••••••••••••••••••••••••••••••••••••••••••••
16.7-Cash Flow and Manpower Loading Requirements ••.••••.••••
16.8-Contingency ••••.•.••••••••••••••.••.•••.••••.•••••••••
17-DEVELOPMENT SCHEDULES •••••••••••••••••••••••.•••••••.•.•••••••
17.1-Preparation of Schedules •.••••••••••••••••••••••••••••
17.2-Watana Schedule ••.••••••••••••..•..•••.•••••••.•••••••.
17.3-Devil Canyon Schedule •••••••••••••••••..•••.•••••••••••
18-ECONOMIC, MARKETING AND FINANCIAL EVALUATION ••••••••••••••••••
18 .. 1 -
18.2
18.3
18.4
18.5
Economic Evaluation ••••••••••.•.••••••••••••••••••••••
Probability Assessment and Risk Analysis ••.•••••••••••.
Marketing •••••••••••••••••••••••••••••••••••••••••••.•
Financial Evaluation ••.••••••.•••••••.••.•••••••••••••
Financial Risk ••••.•••••••••••••••••••••••••••••••••••
19 -CONCLUSIONS AND RECOMMENDATIONS •••••••••.••••••••••••••••••••.
19.1 -Conclusions ••••••••••••••••••••.••••••••••••••••••••••
19.2-Recommendations •••••••••••••••••••••••••••••••••••••.•
14-1
14-1
14-8
14-16
14-21
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18-1
18-15
18-28
18-31
18-37
19-1
19-1
19-2
VOLUME DESCRIPTION
2 ENVIRONMENTAL ASPECTS
(Sections 1 through 11)
3 PLATES
4 Appendix A HYDROLOGICAL STUDIES ,.,~
Al Water Resources Studies
A2 Probable Maximum Flood Study
A3 Reservoir Hydraulic Studies rr""""""~·
A4 Reservoir and River Thermal Studies
AS Climatic Studies for Transmission Line
5 Appendix 8 DESIGN DEVELOPMENT STUUIES
81 Dam Selection Studies
B2 Watana General Arrangement Studies
83 Dev i 1 Canyon General Arrangement Studies
84 Power Facilities Selection Studies
BS Arch Dam Analysis-Devil Canyon
B6 Watana Dam Analysis ~
B7 Site Facilities
B8 Watana Plant Simulation Studies
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6 Appendix c COST ESTIMATES
C1 Watana Hydroelectric Development -Estimate of Cost
C2 Devil Canyon Hydroelectric Development -Estimate of
Cost
C3 Construction Manpower Forecasts
7 Appendix D COORDINATION AND PUBLIC PARTICIPATION !fi~"'"'
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LIST OF TABLES
TABLE TITLE
1.1 Principal Project Parameters
5.1
5.2
5.3
5.4
5.5
5.6
5.7
6.1
6.2
6.3
6.4
6.5
6.6
6.7
7.1
7.2
7.3
7.4
7.5
7.6
7.7
7.8
7.9
7.10
7.11
7.12
7.13
7.14
7.15
7.16
8.1
8.2
8.3
8.4
Historical Annual Growth Rates of Electric Utility Sales
Annual Growth Rates in Utility Customers and Consumption Per Customer
Utility Sales by Railbelt Regions
Summary of Railbelt Electricity Projections
Forecast Total Generation and Peak Loads-Total Railbelt Region
ISER 1980 Railbelt Region Load and Energy Forecasts Used for Generation
Planning Studies for Development Selection
December 1981 Battelle PNL Railbelt Region Load and Energy Forecasts
Used for Generation Planning Studies
Total Generating Capacity Within the Railbelt System
Generating Units Within the Railbelt-1980
Schedule of Planned Utility Additions (1980-1982)
Operating and Economic Parameters for Selected Hydroelectric Plants
Results of Economic Analyses of Alternative Generation Scenarios
Summary of Thermal Generating Resource Plant Parameters/1982$
Alaskan Fuel Reserves
Typical NOAA Climate Data Record
Monthly Summary for Watana Weather Station Data Taken During January
1981
Summary of Climatological Data
Recorded Air Temperatures at Talkeetna and Summit in oF
Pan Evaporation Data
Average Annual and Monthly Flow at Gage in the Susitna Basin
Gold Creek Natural Flows
Watana Estimated Natural Flows
Devil Canyon Estimated Natural Flows
Peak Flows of Record
Estimated Flow Peaks in Susitna River
Maximum Recorded Ice Thickness on the Susitna River
Suspended Sediment Transport in Susitna River
Estimated Sediment Deposition in Reservoirs
Water Appropriations Within One Mile of the Susitna River
Hectares and Percentage of Total Area Covered by Vegetation/Habitat
Types
Potential Hydroelectric Development
Dam Crest and Full Supply Levels
Capital Cost Estimate Summaries-Susitna Basin Dam Schemes -Cost in
$Million 1980
Results of Screening Model
LIST OF TABLES (Cont'd)
TABLE
8.5
8.6
8.7
8.8
8.9
8.10
8.11
8.12
8.13
8.14
8.15
8.16
8.17
8.18
8.19
9.1
9.2
9.3
9.4
9.5
TITLE
Information on the Devil Canyon Dam and Tunnel Schemes
Tunnel Schemes Power Output and Average Annual Energy
Capital Cost Estimate Summaries for Scheme 3 Tunnel Alternative
Costs in $Million 1980
Susitna Environmental Development Plans
Results of Economic Analyses of Susitna Plans
Results of Economic Analyses of Susitna Plans -Low and High Load
Forecast
Basic Economic Data for Evaluation of Plans
Economic Evaluation of Devi 1 Canyon Dam and Tunnel Schemes and
Watana/Devil Canyon and High Devil Canyon/Vee Plans
Environmental Evaluation of Devil Canyon Dam and Tunnel Schemes
Social Evaluation of Susitna Basin Development Schemes/Plans
Energy Contribution Evaluation of the Devil Canyon Dam and Tunnel
Schemes
Overall Evaluation of Tunnel Scheme and Devil Canyon Dam Scheme
Environmental Evaluation of Watana/Devil Canyon and High Devil
Canyon/Vee Development Plans
Energy Contribution Evaluation of the Watana/Devil Canyon and High
Devil Canyon/Vee Plans
Overall Evaluation of the High Devil Canyon/Vee and Watana/Devil Canyon
Dam Plans
Combined Watana and Devil Canyon Operation
Present Worth of Production Costs
Design Data and Design Criteria for Final Review of Layouts
Evaluation Criteria
Summary of Comparative Cost Estimates
10.1 Design Data and Design Criteria for Review of Alternative Layouts
10.2 Summary of Comparative Cost Estimates
11.1 Susitna Access Plans
11.2 Identification of Conflicts
12.1
12.2
12.3
12.4
12.5
12.6
12.7
12.8
12.9
12.10
Watana Peak Work Force and Camp/Village Design Population
Rockfill and Earth Dams in Excess of 500 feet
Summary of Design Data for Large Embankment Dams in Seismically Active
Areas
Dams in Seismic Areas
Generalized Surficial Stratigraphic Column Area 11 D'' and Relict Channel
Ring Follower Gates
Preliminary Unit Data
Assumed Properties for Static Analyses of Watana Dam
Watana Dam -Crest Elevation and Freeboard
Recent High Head Francis Turbines
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LIST OF TABLES (Cont'd)
TABLE TITLE
13.1 Watana Peak Work Force and Camp/Village Design Population
13.2 Arch Dam Experience
13.3 Preliminary Compensation Flow Pump Data
13.4 Preliminary Unit Data
14.1
14.2
14.3
14.4
14.5
14.6
14.7
15.1
15.2
15.3
16.1
16.2
16.3
16.4
18.1
18.2
18.3
18.4
18.5
18.6
18.7
18.8
18.9
18.10
18.11
18.12
18.13
18.14
18.15
18.16
18.17
18.18
Power Transfer Requirements (MW)
Summary of Life Cycle Costs
Transmission System Characteristics
Technical, Economic and Environmental Criteria Used in Corridor
Select ion
Technical, Economic and Environmental Criteria Used in Corridor
Screen ·ing
Summary of Screening Results
EMS Alternatives I and II Comparative Cost Estimates
Energy Potential of Watana -Devil Canyon Developments for Different
Reservoir Operating Rules
Minimum Acceptable Flows Below Watana Dam During Reservoir Filling
Turbine Operating Conditions
Summary of Cost Estimate
Estimate Summary -Watana
Estimate Summary-Devil Canyon
Mitigation Measures -Summary of Costs Incorporated in Construction
Cost Estimates
Real (Inflation Adjusted) Annual Growth in Oil Prices
Domestic Market Prices and Export Opportunity Values in Natural Gas
Summary of Coal Opportunity Values
Summary of Fuel Prices Used in the OGP5 Probability Tree Analysis
Economic Analysis Susitna Project-Base Plan
Summary of Load Forecasts Used for Sensitivity Analysis
Load Forecast Sensitivity Analysis
Discount Rate Sensitivity Analysis
Capital Cost Sensitivity Analysis
Sensitivity Analysis-Updated Base Plan (January 1982) Coal Prices
Sensitivity Analysis-Real Cost Escalation
Sensitivity Analysis -Non-Susitna Plan with Chakachamna
Sensitivity Analysis-Susitna Project Delay
Summary of Sensitivity Analysis Indexes of Net Economic Benefits
Railbelt Utilities Providing Market Potential
List of Generating Plans Supplying Railbelt Region
Forecast Financial Parameters
100% State Appropriation of Total Capital Costs ($5.1 billion in
1982 Dollars)
LIST OF TABLES (Cont'd)
TABLE
18.19
18.20
18.21
18.22
18.23
TITLE
$3 Billion (1982 Dollars) State Appropriation Scenario 7% Inflation and
10% Interest
$2.3 Billion (1982 Dollars) f~inimum State Appropriation Scenario 7'1o
Inflation and 10% Interest
Financing Requirements $Billion for $3.0 Billion State Appropriation
Seen ar io
Financing Requirements-$Billion for $2.3 Billion State Appropriation
Scenario
Basic Parameters of Risk Generation Model
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LIST OF FIGURES
Figure
1.1
1.2
1.3
4.1
Title
Lac at ion Map
Plan Formulation and Selection Methodology
Planning Approach
Damsites Proposed by Others
5.1 Historical Total Railbelt Utility Sales to Final Customers
5.2 ISER 1980 Energy Forecasts Used for Development Selection Studies
5.3 December 1981 Battelle Load and Energy Forecasts Use for Generation
6.1
6.2
6.3
6.4
6.5
6.6
7.1
7.2
7.3
7.4
7.5
7.6
7.7
7.8
7.9
7.10
7.11
7.12
7.13
7.14
7.15
7.16
7.17
7.18
7.19
7.20
Planning Studies
Location Map
Formulation Plans Incorporating Non-Susitna Hydro Generation
Selected Alternative Hydroelectric Sites
Generation Scenario Incorporating Thermal and Alternative Hydropower
Develop11ents -Medium Load Forecast
Formulation of Plans Incorporating All-Thermal Generation
Alternative Generation Scenario-Battelle Medium Load Forecast
Data Collection Stations
Average Annual Flow Distribution Within the Susitna River Basin
Monthly Average Flows in the Susitna River at Gold Creek
Flow Duration Curve Mean Monthly Inflow at Watana Pre-Project
Flow Duration Curve Mean Monthly Inflow at Devil Canyon Pre-Project
Annual Flow Duration Frequency Curves-Susitna River at Gold Creek
1:50 Year Annual Flood Inflow Hydrograph -Susitna River at Watana
Damsite
1:10,000 Year Flood Inflow Hydrograph -Susitna River at Watana
Dams ite
Probable Maximum Flood Inflow Hydrograph -Susitna River at Watana
Dams i te
Suspended Sediment Transport -Susitna River at Selected Station
Regional Geology
Talkeetna Terrain IVJodel and Section
1943 Earthquake Geology Map
Location and Territorial Boundaries of Wolf Packs-1980
Division of Nelchina Caribou Herd Ranges
Relative Densities of Moose-November 1980
Employment, Population and Per Capita Personal Income in the
Matanuska-Susitna Borough and Valdez-Whittier-Chitina Census
Division, 1979-1980
Communities in the Vicinity of Susitna Basin
Existing Structures
Land Use Aggregations
LIST OF FIGURES (Cont'd)
Figure
8.1
8.2
8.3
8.4
8.5
8.6
8.7
9.1
9.2
9.3
9.4
9.5
9.6
9.7
9.8
Title
Susitna Basin Plan Formulation and Selection Process
Profile Through Alternative Sites
Mutually Exclusive Development Alternatives
Schematic Representation of Conceptual Tunnel Schemes
Generation Scenario with Susitna Plan E1.3-Medium Load Forecast
Generation Scenario with Susitna Plan E2.3-Medium Load Forecast
Generation Scenario with Susitna Plan E3.1 -Medium Load Forecast
Watana Geologic Map
Watana Relict Channel -Top of Bedrock
Mean Response Spectra at Devil Canyon and Watana Sites for Safety
Evaluation
Watana Reservoir -Dam Crest Elevation/Present Worth of Product Costs
Watana Diversion -Headwater Elevation/Tunnel Diameter
Watana Diversion -Upstream Cofferdam Costs
Watana Diversion Tunnel and Cofferdam Cost/Tunnel Diameter
Watana Diversion -Total Cost/Tunnel Diameter
10.1 Devil Canyon Geologic Map
10.2 Devil Canyon Diversion -Headwater Elevation Tunnel Diameter
10.3 Devil Canyon Diversion-Total Cost Tunnel Diameter
11.1 Access Plan Selection Methodology
11.2 Plan 2
11.3 Plan 4
11.4 Plan 6
11.5 Plan 8
11.6 Plan 10
11.7 Plan 11
12.1
12.2
12.3
12.4
12.5
12.6
12.7
12.8
12.9
12.10
13.1
13.2
13.3
Watana Diversion-Total Facility Rating Curve
Watana Reservoir Filling Sequence
Watana Reservoir Emergency Drawdown
Watana Comparison of Grain Size Curves for Various Core Materials
Watana Required Grain Size Curves Main Dam
Watana -Composite Grain Size Curve -Borrow Site D
Earthquake Time History
Watana -Unit Output
Watana -Turbine Performance (at Rated Head)
Francis Turbines Specific Speed Experience Curve for Recent Units
Devil Canyon Diversion Rating Curve
Devil Canyon -Unit Output
Devil Canyon -Turbine Performance (at Rated Head)
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LIST OF FIGURES (Cont•d)
Figure
14.1
14.2
14.3
14.4
14.5
14.6
14.7
14.8
14.9
14.10
14.11
14.12
14.13
14.14
14.15
15.1
15.2
15.3
15.4
15.5
16.1
16.2
16.3
18.1
18.2
18.3
18.4
18.5
18.6
18.7
18.8
18.9
18.10
18.11
18.12
Title
Railbelt 345 kV Transmission System Single Line Diagram
Alternative Transmission Line Corridors Southern Study Area
Alternative Transmission Line Corridors Central Study Area
Alternative Transmission Line Corridors Northern Study Area
Anchorage to Fairbanks-Proposed Transmission Line Route
X-Frame Guyed Steel Tower
Transmission Tower Foundation Concepts
Willow Switching Station -General Layout
University Substation -General Layout
Ester and Knik Arm Stations -General Layout
Stations Typical Elevation-Low Level Bus Arrangement
Energy Management System, Alternative I, System Configuration
Energy Management System, Alternative II, System Configuration
Willow System Control Center, Functional Layout
Energy Management System, Alternative I, Configuration Block Diagram
Typical Load Variation in Alaska Railbelt System
Frequency Analysis of Average Annual Energy for Susitna Developments
Watana-Unit Efficiency (at Rated Head)
Devil Canyon-Unit Efficiency (at Rated Head)
Watana Plant Simulation -December 2000
Watana Development Cumulative and Annual Cash Flow January 1982
Dollars
Devil Canyon Development Cumulative and Annual Cash Flow January 1982
Dollars
Susitna Hydroelectric Project Cumulative and Annual Cash Flow Entire
Project January 1982 Dollars
Probability Tree-System with Alternatives to Susitna
Probability Tree-System with Susitna
Susitna Multivariate Sensitivity Analysis -Long Term Costs vs
Cumulative Probability
Susitna Multivariate Sensitivity Analysis-Cumulative Probability vs
Net Benefits
Risk Analysis Study Methodology
Elements of the Risk Analysis
Structural Relationship for Handling Risk Activity Combinations,
Damage Scenarios and Criterion Values
Cumulative Probability Distribution for Watana Project Cost
Cumulative Di str ibut ion of Devil Canyon Costs
Cumulative Probability Distribution for Susitna Hydroelectric Project
Historical Water Resources Project Cost Performance (40 Projects)
Comparison of Susitna Risk Results with Historical Water Resources
Project Cost Performance (48 Projects)
LIST OF FIGURES (Cont 1 d)
Figure
18.13
18.14
18.15
18.16
18.17
18.18
18.19
18.20
18.21
18.22
18.23
18.24
18.25
18.26
18.27
18.28
18.29
18.30
18.31
18.32
18.33
Title
Watana Schedule Distribution Exclusive of Regulatory Risks
Watana Schedule Distribution Including the Effect of Regulatory Risks
Cumulative Probability Distribution for Days of Reduced Energy
Delivery to Anchorage
Cumulative Probability Distribution for Days per Year with No Susitna
Susitna Energy Delivery to Fairbanks
Railbelt Region-Generating and Transmission Facilities
Service Areas of Railbelt Utilities
Relative Distribution of Energy Supply Generating Facilities, Net
Generation for Types of Fuel and Relative Mix of Generating
Technology-Railbelt Utilities 1980
Energy Demand and Deliveries from Susitna
Energy Pricing Comparisons -1994
System Costs Avoided by Oeveloping Susitna
Energy Pricing Comparisons -20U3
Energy Cost Comparison -100 Percent Debt Financing and 7 Percent
Inflation
Energy Cost Comparison-State Appropriations $3 Billion (1982
dollars)
Energy Cost Comparison -$2.3 Bill ion (1982 dollars) -Minimum State
Appropriations
Energy Cost Comparison -Pricing Restricted 94/95 and 03/04
Energy Cost Comparison Meeting SB/646 Requirements with
100 Percent Financing
Energy Cost Comparison Meetings SB/646 Requirements With $3.0
B-ill ion Appropriation
Bond Financing Requirements
Debt Service Cover
Watana Unit Costs as Percent of Best Thermal Option in 1996
Cumulative Net Operating Earnings by 2000
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LIST OF PLATES -VOLUME 1
SECTION 8
8.1
8.2
8.3
8.4
8.5
8.6
8.7
8.8
8.9
SECTION 9
9.1
9.2
9.3
9.4
9.5
9.6
9.7
9.8
9.9
9.10
9.11
SECTION 10
10.1
10.2
10.3
10.4
10.5
SECTION 11
11.1
11.2
Devil Canyon-Hydro Development-Fill Dam
Watana -Hydro Development -Fill Dam
Watana-Staged Fill Dam
High Devil Canyon -Hydro Development
Susitna III -Hydro Development
Vee -Hydro Development
Den a l i and IVlacLaren -Hydro Development
Preferred Tunnel -Scheme 3-Plan View
Preferred Tunnel -Scheme 3 -Sections
Watana-Arch Dam Alternatives
Watana-Alternative Dam Axes
Watana-Preliminary Schemes
Watana-Scheme WP1 -Plan
Watana -Scheme WP3 -Sections
Watan a -Scheme WP2 and WP3
Watana -Scheme WP2 Sections
Watana-Scheme WP4-Plan
Watana -Scheme WP4 -Sections
Watana -Scheme WP3A
Watana -Scheme WP4A
Devil Canyon -Scheme DC1
Devil Canyon -Scheme DC2
Devil Canyon -Scheme DC3
Devil Canyon -Scheme DC4
Devil Canyon -Selected Scheme
Alternative Access Corridors
Alternative Access Routes
LIST OF PLATES -VOLUME 3
WATANA
Plate No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
DEVIL CANYON
40
41
42
Title
Railbelt Area
Reservoir Plan
Site Layout
General Arrangement
Hydrological Data-Sheet 1
Hydrological Data -Sheet 2
Simulated Reservoir Operation
Main Dam -Plan
Main Dam -Sections
Main Dam-Grouting and Drainage
Diversion -General Arrangement
Diversion -Sections
Diversion -Intake Structures
Main Spillway-General Arrangement
Main Spillway -Control Structure
Main Spillway-Chute Sections
Main Spillway-Flip Bucket
Outlet Facilities-General Arrangement
Outlet Facilities-Gate Structure
Emergency Spillway
Emergency Release -Sections
Downstream Portals-Plan and Sections
Power Facilities -General Arrangement
Power Facilities-Access
Power Facilities-Plan and Sections
Power Intake -Sections
Powerhouse-Plans
Powerhouse-Plans
Transformer Gallery-Plan and Sections
Surge Chamber and Tailrace-Sections
Electrical Legend
Powerhouse-Single Line Diagram
Switchyard -Single Line Diagram
Block Schematic Computer Aided Control System
Access Plan-Recommended Route
General Layout-Site Facilities
l'v1ain Construction Camp Site
Village and Town Site
Watana and Devil Canyon-Construction Camp Details
Reservoir Plan
Site Layout
General Arrangement
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LIST OF PLATES -VOLUME 3
Plate No.
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
CONSTRUCTION SCHEDULES
75
76
Title
Hydrological Uata -Sheet 1
Hydrological Oat a -Sheet 2
Simulated Reservoir Operation
Dams-Plan and Profile
Main Darn -Geometry
Main Dam -Crown Section
Main Dam -Sections
Main Dam -Thrust Blocks
Main Dam -Grouting and Drainage
Main Dam-Outlet Facilities
Saddle Darn -Sections
Diversion -General Arrangement
Diversion -Sections
Main Spillway -General Arrangement
Main Spillway-Control Structure
Main Spillway -Chute Section
Emergency Spillway-General Arrangement
Emergency Spillway-Sections
Power Facilities-General Arrangement
Power Facilities -Access
Power Facilities-Plan and Sections
Power Intake -Sections
Powerhouse Plans
Powerhouse -Sections
Transformer Gallery-Plan and Sections
Surge Chamber and Tailrace -Sections
Tailrace Portal -Plan and Sections
Powerhouse -Single Line Diagram
Switchyard -Single Line Diagram
General Layout -Site Facilities
Main Construction Camp Site
Temporary Village
Watana Construction Schedule
Devil Canyon Construction Schedule
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LIST OF REFERENCE REPORTS
The following reports and documents were prepared during the course of the study
program. Specific references in the text of the report are cited and listed
separately by section; they should not be confused with the following list.
Number
R1
R2
R3
R4
R5
R6
R7
R8
R9
R10
Rll
R12
R13
R14
R15
R16
R17
R18
R19
R20
R21
R22
R23
R24
R25
R26
R27
R28
R29
R30
R31
R32
R33
R34
R35
R36
R37
Report
Plan of Study
Plan of Study, Revision 1
Plan of Study, Revision 2
Plan of Study, Revision 3
Forecasting Peak Electrical Demands for
Alaska's Railbelt
Closeout Report, Review of ISEK Work
Task 1 Termination Report, September 1980
Field Reconnaissance of Reservoir Area -
Timber Report
Marketability and Disposal Study for
Reservoir Area
Aerial Photography and Photogrammetric Mapping
Control Network Survey Report
Hydrographic Surveys
Field Data Collection and Processing
Glacier Studies
Reg ion al Flood Studies
Hydraulic and Ice Studies
Reservoir Sedimentation
River Morphology
Review of Available Materials
Field Data Index
Water Quality-Annual Report-1980
Water Quality-Annual Report-1981
Water Quality-Interpretation-1981
Ice Observations -1980
Processed Climatic Data for Six Weather Stations
(6 volumes)
Interim Report on Seismic Studies
Final Report on Seismic Studies
1980 Geotechnical Report (Superceded by R29)
1980-81 Geotechnical Report
OGP Data
Develop11ent Selection Report
Review of Previous Studies and Reports
Closeout Report February 1981
Tunnel Alternative Report July 1981
Evaluation of Arch Dam at Devil Canyon Site
1981 Upper Limit Capital Cost Estimate, July 1981
Scour Hole Development Downstream of High
Head Dams
1980 Summary Environmental Report
Prepared By
Acres
Acres
Acres
Acres
wee
Acres
Acres
R&M
R&M
R&M
R&M
R&M
R&M
R&M/U. of Alaska
R&M
R&M/ Acres
R&M
R&M
Acres
R&M
R&~1
R&M
R&M
R&M
R&M
wee wee
Acres
Acres
Acres
Acres
Acres
Acres
Acres
Acres
Acres
TES
LIST OF REFERENCE REPORTS (Cont 1 d)
Number
R38
R39
R40
R41
R42
R43
R44
R45
R46
R47
R48
R49
R50
R51
R52
R53
R54
R55
R56
R57
R5b
R59
R60
R61
R62
R63
R64
R65
R66
R67
R68
R69
R70
R71
R72
R73
Report
Environmental Report -Fish Ecology -1980
Environmental Report-Plant Ecology-1980
Environmental Report -Big Game -1980
Environmental Report -Birds and Non Game
Mammals -1980
Environmental Report -Furbearers -1980
Environmental Report -Land Use Analysis -1980
Environmental Report-Socioeconomics-1980
Environmental Report Cultural Resources -1980
Fish and Wildlife Mitigation Policy-Revised
Instream Flow Study Plan
Draft Fishery Mitigation Plan
Draft Wildlife Mitigation Plan
Phase 1 Report -Fish Ecology
Phase 1 Report -Big Game
Phase 1 Report-Plant Ecology
Phase 1 Report -Bird and Non-Game Mammals
Phase 1 Report -Furbearers
Phase 1 Report -Land Use
Phase 1 Report -Socioeconomics
Phase 1 Report -Cultural Resources
Phase 1 Report -Recreation
Sociocultural Report
Environmental Analysis of Alternative Access Plan
Access Planning Study
Access Route Selection Report
Electric System Studies
Transmission Line Corridor Screening Report
Transmission Line Selected Route
Switching Stations and Substations -Single
Line Diagrams
Agency Consultation Report
Initial Version Preliminary Licensing
Documentation, April 1980
Preliminary Licensing Documentation-2nd Version
November 1981
Status of Susitna Basin Water Rights
Project Overview Report, 2nd Draft
Economic Marketing and Financial Evaluation
Susitna Risk Analysis
Prepared By
TES
TES
TES
TES
TES
TES
TES
TES
TES/ Acres
Acres
TES
TES
ADF&G
ADF&G
TES
TES
TES
TES
TES
TES
TES
Acres
TES
R&rvJ
Acres
Acres
Acres
Acres/TES
Acres
Acres
Acres
Acres
Acres
Acres
Acres
Acres
-I .
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1 -INTRODUCTION
This Feasibility Report has been prepared by Acres American Incorpor-
ated (Acres) for the Alaska Power Authority under the terms of an
Agreement, dated December 19, 1979, to conduct a feasibility study and
prepare a license application to the Federal Energy Regulatory Commis-
sion (FERC).
The feasibility study was undertaken in accordance with the Plan of
Study (POS) for the Susitna Hydroelectric Project, which was first is-
sued by the Power Authority for public review and comment on February
4, 1980. Three revisions to the POS were issued in September, 1980,
December, 1981, and January, 1982 to take account of public, federal,
and state agency comments and concerns. The POS 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, which is currently
scheduled for September 30, 1982. The fi 1 ing of the FERC license
application is contingent upon acceptance of ·the findings of this
report in terms of project feasibility and environmental acceptability
by the state, and a decision to proceed with developmental efforts.
Studies by Acres through March, 1981 were mainly concerned with evalua-
tion of the need for electric power in the Alaska Railbelt Region and
preliminary consideration of the alternatives for meeting these power
needs both with and without a Susitna Basin hydroelectric development.
This work was undertaken in parallel with Railbelt power demand fore-
casting studies undertaken by the Institute for Social and Economic
Research (ISER) for the State of Alaska. The results of these studies
were presented in June, 1981, in a Development Selection Report which
described these initial steps in the POS process and provided recommen-
dations and justification for continuation of study of basin develop-
ment at two sites, Watana and Devil Canyon.
Subsequent to selection of this basin development plan, engineering
studies were continued to develop preliminary design and cost informa-
tion for the Watana and Devi 1 Canyon sites. These design development
studies were updated in conjunction with an independent study of alter-
natives for meeting projected Railbelt electrical power requirements by
Battelle Pacific Northwest Laboratories, undertaken for the State of
Alaska. All of this information was used to establish definitive pro-
ject arrangements for Watana and Devil Canyon as well as for the asso-
ciated transmission facilities, to develop estimates of construction
and operating costs, to undertake an economic and financial evaluation
for the Susitna Hydroelectric Project, and to assess the environmental
impact of the project and appropriate mitigation measures. The remain-
der of this section deals with a description of the study area and the
proposed SusJtna development and a summary of the objectives and scope
of the current studies.
1-1
1.1 -The Study Area
The main stream of the Susitna River originates about 90 miles south of
Fairbanks where melting glaciers contribute much of its summer flow.
Meandering for the first 50 mi 1 es in a southerly direction across a
broad a 11 uv i a 1 fan and p 1 ate au, the river 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 1 owl and to Cook In 1 et, about 30 mi 1 es west of Anchorage. The
vast hydroelectric potential of this river has been recognized and
studied for more than 30 years. Strategically located in the heart of
the South Central Rai lbelt, the Susitna Basin could be harnessed to
produce about twice as much electrical energy per year as is now being
consumed in the Ra i 1 be 1 t region. The genera 1 1 ocat ion of the Susi tna
Basin within the Railbelt area is shown on Figure 1.1.
The Susitna River system, with a drainage area of more than 19,000
square miles, is the sixth largest in Alaska. Major tributaries in-
clude the Yentna, Chulitna, Talkeetna, and Tyone rivers. A substantial
portion of the total annual streamflow 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 supply and are generally free of sediment. Freezing starts in
October in the upper reaches of the basin; by late November, ice covers
have formed on all but the most rapidly flowing stretches of the river.
Breakup generally occurs during 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. Extensive studies are
necessary to determine the total value of these wildlife resources, the
impacts which any development may have upon them, and the nature of
mitigative measures which might be taken to eliminate or offset nega-
tive environmental consequences of hydroelectric development.
1.2 -Project Description
The Susitna Basin has been under study since the mid 1940s by agencies
such as the U.S. Bureau of Reclamation (USBR), the Alaska Power Admin-
istration, and the US Army Corps of Engineers ( COE), as we 11 as H. H.
Kaiser and Company. The more recent and most comprehensive of these
studies was carried out by the COE. The optimum method of developing
the hydroelectric potential of the basin was determined by the COE to
comprise two major developments. The first of these would require a
dam at the Watana site at approximately mile 184 up the Susitna River,
and the second, a dam at the Devi 1 Canyon site, approximately 31 miles
downstream of Watana. The locations of these sites are shown on Figure
1.1. This development was found to be economically viable and would
provide the Railbelt area with a long-term supply of relatively cheap
and reliable energy.
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Development selection studies completed by Acres in 1981 confirmed that
the preferred Susitna development plan should consist of two large hy-
droelectric dams at Watana and Devil Canyon. The Development Selection
Report recommended further study of hydroe 1 ectri c i nsta 11 at ions at
these two sites. The preliminary studies indicated that an earthfill
dam, roughly 880 feet maximum height, would be constructed at Watana
first. The large reservoir volume created would provide adequate stor-
age for seasonal regulation of the flow. Initially, approximately 400
MW of generating capacity would be installed at this site. This would
later be expanded to around 800 MW to allow for additional peaking ca-
pacity. The Devi 1 Canyon dam would be the next stage of the develop-
ment. It would involve a 675-foot maximum height double curvature con-
crete arch dam and incorporate a 400 MW powerhouse. The total average
annual energy yield from this development was estimated as 6200 GWh.
The Watana and De vi 1 Canyon deve 1 opments together comprise the Susitna
Hydroelectric Project.
Design studies undertaken subsequent to the selection of the Susitna
development plan confirmed that the optimum installed generating capac-
ity for Watana should ultimately be 1020 MW, and that first power
should be available in 1993. Devil Canyon would add 600 MW to the sys-
tem by 2002. The most suitable access route to the site would involve
a road from the Parks Highway southeast to Gold Creek, then along the
south side of the Susitna River to Devil Canyon and along the north
side of the river to Watana. The power from the two sites would be
conveyed by five 345 kV transmission lines to the proposed Anchorage-
Fairbanks intertie at Gold Creek. The connection to Fairbanks would
finally consist of double 345 kV lines, and to Anchorage triple 345 kV
lines via a cable crossing at Knik Arm near Point Mackenzie.
1.3 -Objectives and Scope of Current Studies
The assessment of feasibility of an undertaking as significant as the
proposed Susitna Hydroelectric Project required an appropriately high
level of effort in terms of field and office activities. Three primary
objectives were first identified:
-To determine technical, economic and financial feasibility of the
Susitna Project to meet future power needs of the Railbelt Region of
the State of Alaska;
-To evaluate the environmental consequences of designing and construc-
ting the Susitna Project; and
-To file a completed license application with the Federal Energy Reg-
ulatory Commission (FERC).
The scope of work was carefully structured to meet these objectives in
the available time frame in a manner appropriate to the scale, variety,
1-3
and complexity of the problems involved. The POS was originally pre-
pared and revised three times to address in almost exhaustive detail
the numerous work tasks and the many engineering, scientific, adminis-
trative, and associate~ supporting skills required.
A total of twelve major areas of study or tasks were identified:
-Task 1:
-Task 2:
-Task 3:
-Task 4:
-Task 5:
-Task 6:
-Task 7:
-Task 8:
-Task 9:
Task 10:
-Task 11:
-Task 12:
Power Studies
Surveys and Site Facilities
Hydrology
Seismic Studies
Geotechnical Exploration
Design Development
Environmental Studies
Transmission
Construction Cost Estimates and Schedules
Licensing
Marketing and Financing
Public Participation Program
Two further tasks, 00 (Project Management) and 13 (Administration) were
also established. These tasks were originally further subdivided into
a total of 150 subtasks, ranging from five to 31 subtasks on a task-by-
task basis. Revisions to the POS resulted in an additional 10 sub-
tasks, the largest task then accounting for 39 subtasks.
Activities ranged from engineering and scientific data acquisitions,
literature review, research, dam studies, design computations and anal-
ysis, to field surveys, hydraulic measurements, seismologic observa-
tions, geologic mapping, geotechnical exploration, environmental data
gathering, and the necessary logistical support services. The study
directly involved up to as many as 300 participants at one time and
drew upon a broad cross-section of contributions from expert special-
ists to concerned citizens.
1.4 -Plan Formulation Selection Process
A key element in the studies undertaken was the process applied for
formulation and comparison of development plans. Emphasis was placed
on consideration of every important perspective which could influence
the selection of a particular course of action from a number of pos-
sible alternatives. An essential component of this planning process
involved a generalized multi-objective development selection methodol-
ogy for guiding the planning decisions. A second important factor was
the formulation of a consistent and rational approach to the economic
analyses undertaken by the studies.
(a) Planning Methodology
A generalized plan formulation and selection process was developed
to guide the various planning studies being conducted. Of the
numerous planning decisions made in these studies, perhaps the
1-4
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most important were 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 involved the identification of feasible candi-
dates and courses of action, followed by the development and ap-
p 1 i cation of an appropriate screening process. In the screening
process, less favorable candidates were eliminated on the basis of
economic, environmental, social, and other prescribed criteria.
Plans were then formulated which incorporated the shortlisted can-
didates individually or in appropriate combinations. Finally, a
more detailed evaluation of the plans was carried out, again using
prescribed criteria and aimed at selecting the best development
plan. Figures 1.1, 1.2, and 1.3 illustrate this general process.
In the final evaluation, no attempt was made to quantify all the
attributes used and to combine these into an overall numerical
evaluation. Instead, the plans were compared utilizing both quan-
titative and qualitive attributes; where necessary, judgmental
tradeoffs between the two types of attributes were made and high-
lighted. This allows reviewers of the planning process to quickly
focus on the key tradeoffs that affect the decisions. To facili-
tate this procedure, a paired comparison technique was used so
that at any one step in the planning process, only two plans were
being evaluated.
b) Economic Analyses
Since the proposed Susitna development is a public or state pro-
ject, all planning studies described were carried out using eco-
nomic parameters as a basis of evaluation. This ensured that the
resulting investment decisions maximized benefits to the state as
a whole rather than any individual group or groups of residents.
The economic analyses incorporated the following principles:
-Intra-state transfer payments such as taxes and subsidies were
excluded.
-Opportunity values were used to establish the costs for coal,
oil, and natural gas resources used for power generation in the
alternatives considered. These opportunity costs were 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 ignored the existence of current term-
contractual commitments which may exist, and which fix resource
costs at values different from the opportunity costs.
-The analyses were conducted using "real" or inflation-adjusted
parameters. This means that the interest or discount rate used
equaled the assessed market rate minus the general rate of in-
flation. Similarly, the fuel and construction cost escalation
1-5
rates were adjusted to reflect the rate over or under the gen-
eral inflation rate.
A 3 percent discount rate was used as the basis of the economic
analysis. A lower value would tend to improve the relative
economic position of capital intensive projects (such as hydro
generation) versus high level cosumptive projects (such as
thermal generation). A higher value would have the opposite
effect.
1.5 -Organization of Report
The objective of this report is to describe the studies undertaken to
establish the feasibility of the Susitna Hydroelectric Project.
In order to improve the continuity and clarity of the report, much of
the detailed technical and environmental material is included in sepa-
rate appendices. The report is organized as follows:
Volume 1 -Engineering and Economic Aspects
Section 1: Introduction
A brief summary of the background of the Feasibility Report is pre-
sented in this section.
Section 2: Summary
This section contains a complete summary of Sections 4 through 19 of
Volume 1.
Section 3: Scope of Work
This section outlines the scope of work .associated with the results of
the Feasibility Study presented in this report.
Section 4: Previous Studies
A brief summary of previous Susitna Basin studies undertaken by others
is given in this section.
Section 5: Railbelt Load Forecasts
In this section, the results of the energy and load forecast studies
undertaken by ISER, Woodward-Clyde Consultants, and Battelle are sum-
marized. It concludes with a discussion of the range of load forecasts
used in the Susitna Basin planning studies.
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Section 6: Railbelt System and Future Power Generating Options
This section describes currently feasible alternatives considered in
this study for generating e 1 ectri ca 1 energy to meet future Rai 1 be 1 t
needs. It incorporates data on the performance and costs of the facil-
lt i es.
Section 7: Susitna Basin
This section provides a description of the physical characteristics of
the Susitna Basin including climatologic, hydrologic, geologic, seis-
mic, and environmental aspects.
Section 8: Susitna Basin Development Selection
This section outlines the engineering and planning studies undertaken
for formulation of Susitna Basin Development Plans and selection of the
preferred plan. The selected plan is compared to alternative methods
of generating Railbelt energy needs on the basis of technical, eco-
nomic, environmental and social considerations.
Section 9: Selection of Watana General Arrangement
This section describes the evolution of the general arrangement of the
Watana Project. The site topography, geology, and seismicity of the
Watana site is outlined relative to the design and arrangement of the
various site facilities. The process by which reservoir operating lev-
els and the installed generating capacity of the power facilities were
selected is presented, along with the selection of project design
floods.
Section 10: Selection of Devil Canyon General Arrangement
The development of the general arrangement of the Devil Canyon Project
is described in this section, in a manner similar to that outlined for
Section 9.
Section 11: Selection of Main Access Plan
This section describes the process for selection of the main access
plan, together with a discussion of the· various economic, technical,
environmental and socioeconomic factors which influenced the selection
of the selected plan.
Section 12: Watana Development
The various structures, permanent equipment, and systems which comprise
the Watana Development are described in this section.
Section 13: Devil Canyon Development
This section presents a description of the structures, permanent equip-
ment, and systems which comprise the Devil Canyon Development.
1-7
Section 14; Transmission Facilities
The studies undertaken to select a power delivery system from the
Watana and Devil Canyon Developments to the major load centers in
Anchorage and Fairbanks are described in this section.
Section 15: Project Operation
This section describes the proposed operation of the Watana and Devil
Canyon developments within the framework of the various requirements of
energy demand and physical and environmental restraints. The depend-
able capacity and annual energy production for both developments are
presented, together with a description of operating and maintenance
f aci 1 it i es and procedures and· proposed performance monitoring of the
various project structures.
Section 16: Estimates of Cost
This section summarizes construction costs, mitigation costs, operat-
ing, maintenance and replacement costs, as well as indirect costs such
as engineering and administration costs, and allowance for funds used
during construction.
Section 17: Development Schedule
The schedule for planning, licensing, design, procurement, construc-
tion, and startup of the Watana and Devil Canyon Developments, together
with transmission facilities, is presented.
Section 18: Economic and Financial Evaluation
This section presents the economic and financial evaluation for the
Susitna Hydroelectric Project. A discussion of power marketing options
is also given.
Section 19: Conclusions and Recommendations
This section presents the main conclusions of the feasibility study,
together with recommendations regarding further action which should be
undertaken by the Power Authority.
Volume 2 -Environmental Aspects
This volume of the Feasibility Report describes the environmental re-
sources of the Upper Susitna Basin with specific emphasis on the pro-
posed Watana and Devil Canyon impoundment areas. Section 1 contains a
general description of the locale. Sections 2 through 9 contain de-
tailed information on water use and quality; fish, wildlife, and botan-
ical resources; historic and archaeological resources; socioeconomic
impacts; geological and soil resources; recreational and aesthetic re-
sources; and land use. This information is then utilized to predict
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impacts of the construction and operation of the reservoirs, trans-
mission lines, and access road on the natural resources and socioeco-
nomic conditions in the project area. In Section 10, alternatives to
the proposed project are discussed and evaluated from the environmental
point of view. These alternatives include hydroelectric development
within and outside the Upper Susitna Basin and thermal and tidal power
development. A list of literature relative to the study is presented
in Section 11.
Volume 3 -Plates
This volume contains all of the plates pertaining to the Feasibility
Report.
Volume 4 -Appendix A-Hydrological Studies
This volume includes detailed supportive data for water resource
studies and flood studies, reservoir hydraulic and thermal studies,
and climatic studies for transmission lines.
Volume 5 -Appendix B -Design Development Studies
This volume contains background and supporting data for dam selection
and design studies, project layout studies, power facilities selection
studies, and power plant operation studies.
Volume 6 -Appendix C -Cost Estimates
Detailed cost estimates and supporting cost data are presented in this
volume.
Volume 7 -Appendix D -Public Participation and Agency Consultation
This volume contains a list of agencies contacted and copies of corres-
pondence from agencies relative to the study. It also explains the
programs developed to ensure agency input into planning and decision
making associated with the project. This volume also describes the
public participation program and presents a summary of public partici-
pation meetings conducted during the study program.
1.6 -Principal Project Parameters
Table 1.1 sets out the-principal project parameters for the proposed
Watana and Devil Canyon projects as determined by the studies presented
in this report.
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TABLE 1.1: PRINCIPAL PROJECT PARAMETERS
Item
Hydrology
-Average River Flow (cfs)
-Peak Flood Inflows (cfs)
PMF
• 10,000 year
• 100 year
Reservoir Characteristics
-Normal Maximum Operating level ( ft)
-Maximum level, PMF (ft)
-Minimum Operating level (ft)
-Area at NMOL (acres)
-length (miles)
-Total Storage (acres/feet)
-live Storage (acres/feet)
Project Outputs
-Plant Design Capability (MW)
-Annual Generation (GWh)
• Firm
• Average
Dams
-Type
-Crest Elevation ( ft)
-Crest length (ft)
-Height Above Foundation (ft)
-Crest Width ( ft)
-Upstream Slope (H:V)
-Downst~eam Slope (H:V)
Diversion
-Cofferdams
Type
Upstream Crest Elevation (ft)
Downstream Crest Elevation ( ft)
Maximum U/S Water Level (ft)
-Tunnels
Number/Type
• Diameter ( ft)
. Capacity (cfs)
Outlet Facilities
-Central Structures
-Diameter (in)
-Water Passage Diameter (ft)
-Capacity (cfs)
Watana
7,940
326,000
156,000
92,000
2,185
2,202
2,045
38,000
48 6
9.5 X 10 6 4.4 X 10
1' 020
2,630
3,450
Earth/Rockfill,
Central Core
2,210
4,100
885
35
2. 4:1
2:1
Rock fill,
Central Core
1,545
1,472
1,536
2 -Circular,
concrete-lined
38
80,500
6-fixed cone valves
78
28
24,000
Devil Canyon
9,040
346,000
165,000
61,000
1 '445
1,466
1 '405
7,800
26 6
1.1x10 6 0.35 X 10
600
2,770
3,340
Concrete Arch
(Earth/Rock fill
Saddle)
1,463 (1472)
1,650 (950)
646 (245)
20 (35)
-(2.4: 1)
-( 2: 1)
Rock fill,
Central Core
947
898
944
-Horseshoe,
concrete-lined
30
36,000
7-fixed cone valves
4-102, 3-90
8.5/7.5
38,500
TABLE 1.1 (Cont'd)
Item
Main Spillways
-Capacity (cfs)
-Control Structure
Type
• Crest Elevation (ft)
• Gates ( H x W, ft )
-Chute Width (ft)
-Energy Dissipation
Emergency Spillways
-Capacity (cfs)
-Control Structure
• Type
• Crest Elevation ( ft)
-Chute Width (ft)
Power Intakes
-Control Structures
-Gates (H x W, ft)
-Crest Elevation ( ft)
-Maximum Drawdown (ft)
-Capacity, percent (cfs)
Penstocks
-Number
-Type
-Diameter (ft)
• Concrete-lined
• Steel-lined
Powerhouses
-Type
-Cavern Size (L x W x H, ft)
-Turbine/Generator
-Speed (rpm)
-Design Unit Capability
• Net head ( ft)
• Flow (cfs)
• Output (MW)
-Rated Unit Capability
Net Head ( ft)
Full Gate Flow (cfs)
Full Gate Output (MW)
Best Gate Output (MW)
-Transformers
Location
Cavern Size (L x W x H, ft)
Number/Type
Voltage (kV)
Rating (MVA)
Watana
115,000
gated ogee
2,148
3-49 X 36
144/80
Flip bucket
140,000
Open channel/
fuse plug
2200/2201.5
310/200
Multi-level, gated
4-1 B X 30
2, 012
140
3,870
6
Inc lined/horizontal
17
15
Underground
455 X 74 X 126
6 Vertical Franc is/
Synchr.
225
652
3,510
170
680
3,550
1,089
924
Upstream gallery
314 X 45 X 40
9 -single phase
15/345
145
Devil Canyon
125,000
gated ogee
1,404
3-54 X 35
122/65
Flip bucket
160,000
Open channel/
fuse plug
1464/1465.5
220
Single level, gated
1-25 X 20
1,364
50
3,670
4
Inclined/horizontal
20
15
Underground
360 X 74 X 126
4 Vertical Francis/
Synchr.
225
542
3, 710
150
575
3,790
656
560
upstream gallery
446 X 43 X 40
12 -single phase
15/345
70
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TABLE 1.1 (Cont'd)
Item
Tailrace Tunnels
-Number/Type
-Diameter (ft)
-Surge Chamber Size (L x W x H, ft)
-Capacity (cfs)
Watana
2 -Horseshoe,
concrete-lined
34
350 X 50 X 150
22,000
Devil Canyon
1 -Horseshoe
concrete-lined
38
300 X 75 X 190
15,500
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LOCATION MAP
LEGEND
\1' PROPOSED r DAM SITES
i
,.
I
----SCALE IN IIIILES
LOCATION MAP FIGURE 1.1.
~ .. ·~~ -""'---·~\ ... ·t
DEFINE
OBJECTIVES
€--~ ·'l ~-.r-:. __ '1 ~-, r-~~-~ "t f·--:-·-· l ······~·]· ,~,~----~ ··r. , .. 1 -~---t .~., --~~,. r~---,_._-_
INPUT FROM AVAILABLE SOURCES -PREVIOUS AND CURRENT STUDIES
FEEDBACK
FEEDBACK
PLAN FORMULATION AND SELECTION METHODOLOGY
} -< .• ·t ,e'( ~--.. ,, l
LEGEND
~ STEP NUMBER IN
4 STANDARD PROCESS
(APPENDIX A '
1
FIGURE 1.2 -
1 ''~~''1 ~~-t
' -·'
,,,_l ,>-.~-.·-·~ -) ·-· ·-. l
DEVELOPMENT OF AN ALL
THERMAL GENERATING PLAN
DEVELOPMENT OF AN OTHER
HYDRO GENERATING PLAN
DEVELOPMENT OF A SUSITNA
BASIN GENERATING PLAN
,,
-~~ ,_1 :·! •''·-·l
ALL
THERMAL
PLAN
OTHER
HYDRO
PLAN
SUSITNA
PLAN
't -. '1 ' 1 1 "} h 'l _,.... ____ / )
DEVELOPMENT OF THE BEST
GENERATING SCENARIO
LEGEND
)
APPLICATION OF PLAN
FORMULATION AND
L------, SELECTION METHODOLOGY
0 END PRODUCTS
'
PLANNING APPROACH
FIGURE 1.3 •
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2 -SUrYIMARY
This section presents a summary discussion of the contents of the fea-
sibility report.
2.1 -Scope of Work
Activities under the Acres Plan of Study (POS) for the Susitna Project
Feasibility assessment have been in progress from January 1980 to the
present time. The study has involved detailed investigations of the
numerous technical, economic, financial, environmental and institution-
al factors to be considered in an undertaking this large.
2.2 -Previous Studies
The hydroelectric potential of the Susitna River Basin has been the
subject of numerous studies' since shortly after World War II. An ini-
tial report on hydroelectric resources in Alaska, issued by the USBR in
1948 and updated in 1952, highlighted the development potential of the
Susitna River. Subsequent studies and reports by the Department of the
Interior (1961), the Alaska Power Administration (1974) and the Henry
J. Kaiser Company (1974) confirmed the desirability of proceeding with
hydroelectric development of the river at a number of different sites.
Studies of the river basin by the COE in 1975 and 1979 culminated in
the recommendation that development should proceed at the Watana and
Devil Canyon sites.
2.3-Railbelt Load Forecasts
Between 1940 and 1978, electricity sales in the Railbelt area grew at
an average annual rate of 15.2 percent, about twice the national aver-
age. Between 1973 and 1978 the rate of growth fell to 10.9 percent.
The two main reasons for these differences are the relatively higher
growth rates in Alaska for both population and the proportion of house-
holds served by electric utilities.
Total utility sales in the Railbelt in 1980 reached 2,390 GWh, requir-
ing 510 MW of generating capacity, at a load factor of 62.5 percent.
Approximately 80 percent of these sales were consumed in the Anchorage
area, about 19 percent in the Fairbanks area and the remainder in the
Glenallen-Valdez area. In recent years approximately 47 percent of
sales has been consumed by the residential sector, attributable mostly
to space heating with smaller uses for lighting and domestic appliances
such as refrigerators, water heaters and ranges. The remaining 53 per-
cent has been accounted for by the commerical-industri al-government
sectors. These proportions compare with national averages of 34 per-
cent and 65 percent respectively.
Forecasts of· Railbelt energy demand by Battelle Pacific Northwest Lab-
oratories in December, 1981 range from 6,303 GWh to 11,435 GWh in the
2-1
year 2010 for projected low and high growth scenarios. Railbelt gener-
ation planning studies undertaken for Susitna feasibility assessment
are based on the Battelle December, 1981 forecast for a medium load
growth scenario. In this case an energy demand of 7,791 GWh is fore-
cast for 2010, requiring 1,537 MW of generating capacity at a projected
load factor of 57.9 percent. This forecast is based on average annual
growth rates from 1981 varying from 4.9 percent through 1990 to 3.5
percent overall. Sensitivity studies were also undertaken to test the
low and high forecast scenarios and the potential impacts of energy
conservation measures.
2.4-Railbelt System and Future Power Generation Options
Planning of future electric power generation for the Railbelt Kegion
must give careful consideration to economic necessity, acceptable envi-
ronmental impacts, and social preferences. Development of the Susitna
Basin could provide a major portion of the Railbelt Region energy needs
well beyond the year 2000. However, this is but one of the available
options for meeting Susitna Railbelt demand.
( a) Ex i s t i n g S ys t em
The two major load centers of the Railbelt Region are the Anchor-
age-Cook Inlet area and the Fairbanks-Tanana Valley area. At pre-
sent, these two areas operate independently. There are currently
nine electric utilities, including the Alaska Power Administra-
tion, providing power and energy to the Railbelt system. In 1980,
total Railbelt installed capacity of 984 MW consisted of two hyd-
roelectric plants totaling 46 MW plus 938 MW of thermal generation
units fired by oil, gas, or coal. An additional 12 MW of hydro
has recently been commissioned by Copper Valley Electric Associa-
tion at Solomon Gulch. Hydroelectric developments normally have a
useful life of 50 years or more and thermal plants 20 to 35 years.
Five more projects are currently expected to be added to the Rail-
belt system prior to 1990:
-Chugach Electric Association: Beluga No.8 combined cycle, 178
MW (total plant), in progress; Bernice Lake No. 4 gas-turbine,
26 .4 MW, 1982.
-Anchorage Municipal Light and Power Department:
gas-turbine, 90 MW, 1982.
AMLPD No. 8
-Corps of Engineers: Bradley Lake hydroelectric, 90 MW, 1988.
-Alaska Power Authority: Grant Lake hydroelectric, 7 ~W, 1988.
Engineering studies are currently in progress for construction of
an i ntert ie between the Anchorage and Fairbanks systems. These
studies indicate that there is an economic benefit in having this
intertie capability. As presently envisaged, the connection will
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involve a 345 kV transmission line between Willow and Healy sche-
duled for completion in 1984. The line will initially be operated
at 138 kV with the capability for expansion as the loads grow in
the load centers.
Alternative Generating Sources
Current forecasts of Railbelt demand indicate that a significant
amount of new generating capacity will be needed by 1993 in addi-
tion to that already planned. A number of alternatives exist for
meeting.these needs. A significant amount of non-Susitna hydro-
electric potential identified in the Railbelt Region includes the
following more attractive developments:
-Chakachamna (330 MW);
-Keetna (100 MW); and
-Snow (50 JVJW).
Although these sources would have generally stable energy costs
once constructed, they would not alone be sufficient to meet pro-
jected demand, and they are relatively more costly than Susitna.
Tne major portion of generating capability in the Kailbelt is cur-
rently thermal, principally natural gas with some coal and oil-
fired installations. There is no doubt that the future electric
energy demand in the Railbelt could be satisfied by all-thermal
generation mix, but the continued rise in cost of fuels would lead
to significant increases in long-term energy costs using these al-
ternatives. The broader perspectives of other alternative re-
sources and the relevant environmental, social, and other issues
involved have been addressed in the Battelle Alternatives Study.
Emphasis in the Acres study was placed in the following more
likely alternative forms of thermal power generation:
-Coal-fired steam;
-Gas-fired combined-cycle;
-Gas-fired gas turbine; and
-Diesel.
(c) Coal-Fired Steam
There are currently two small coal-fired steam plants in operation
in the Railbelt, as well as minor installations at military and
university facilities. New coal-fired plants are likely to be
sited at the undeveloped Beluga field or near Nenana, using Healy
field coal, servicing the Fairbanks load center.
Estimated costs for a 10,000 BTU/kWh 200 MW plant range from $2242
to $2309 per kW in 1982, including provisions for meeting the
national New Performance Standards, and interest during construc-
tion. A construction period of five to six years is required.
2-3
Fuel costs based on long-term opportunity values were set at
$1.43/MM BTU for Beluga field coal and $1.75/MM BTU for Healy coal
to be used at Nenana. Real escalation on these values was esti-
mated as 2.3 to 2.6 percent through the year 2000, falling to 1.1
to 1.2 percent through 2010. O&M costs for coal-fired plants were
estimated as $16.83/kW-year and $0.60/MWh.
(d) Combined Cycle
Combined cycle plants achieve higher efficiencies than conven-
tional gas turbines. There are two combined cycle plants in
Alaska at present, one operational and the other Beluga No. 9 unit
owned by Chugach Electric Association, under construction. A 60
!VIW steam turbine will be added to the system sometime in 1982.
Capital costs for a 8,000 BTU/kWh 200 JVlW unit in 1982 are esti-
mated as $1075 to $1107 per kW. The combined cycle facilities
would burn only gas with a domestic market value of $3.00 per MM
BTU, reflecting the equitable value of gas in Anchorage, assuming
development of the export market. Currently, the local incre-
mental gas market price is about one-third 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 2.5 percent (1982-2000)
and 2 percent (2000-2010) was assumed. O&M costs were assumed at
$7.25/ kW-year and $1.69/MWh.
(e) Gas Turbine
Gas turbines are by far the main source of thermal power generat-
ing resources in the Railbelt area at present. There are 470 MW
of installed gas turbines operating on natural gas in the Anchor-
age area and approximately 168 MW of oil-fired gas turbines sup-
plying the Fairbanks area.
A 10,000 BTU/kWh, 75 MW gas-turbine plant would costs $636 to
$627 /kW and could be built over a two-year construct ion period.
Gas-turbine units can be operated on oil as well as natural gas.
The opportunity value and market cost for oil are considered to be
equal, at $6.50 per mill ion BTU. The real annu<:~l growth rates in
oil costs used were 2 percent for 1982-2000 and 1 percent for
2000-2010. O&M costs for gas turbines were assumed as $2. 70/kW-
year and $4.80/MWh.
(f) Diesel Power Generation
Most diesel plants in the Railbelt tocjay are on standby status or
are operated only for peak load service. About 65 MW of diesel
plant capacity is currently available. The high cost of diesel
fuel and relatively low capital cost of $e5ti to $869/kW makes new
diesel pl9.nts most effective for emergency use or in remote areas
where small loads exist. A unit size of 10 MW was selected as
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appropriate for this type of facility. Diesel fuel costs and
growth rates are the same as oil costs for gas turbines.
Generation Scenarios Without Susitna
To assess economics of developing the Susitna project, the costs
of meeting the Alaska Railbelt load forecast with and without the
project have been compared. Thus, plans were developed using ap-
propriate combinations of the alternative hydroelectric and ther-
mal generating sources identified above. The resulting all-
thermal and mixed hydro-thermal generating scenarios were used as
a basis for comparison with appropriate Susitna-thermal generating
scenarios developed to meet the projected Railbelt comparisons of
a much broader range of possible types of generation were also
made by Battelle in its alternatives study. These studies were
made using economic parameters over a wide range of load fore-
casts, capital costs, interest (discount) rates, fuel cost and
fuel escalation rates.
The results of Acres initial planning studies through early 1~81
were documented in the June 1~81 Development Selection Report.
These studies concluded that Susitna showed promise of economic
feasibility and was worthy of further study. Of the available
non-Susitna alternatives the study showed that the all-thermal
generation scenario was the most l·ikely competitor. Confirmation
of the without-Susitna generation scenario was possible using the
results of the Battelle study for load forecasts, alternative
plant and fuel costs and considering a range of project cost esca-
lation rates. On this basis, the following plan has now been
established as the non-Susitna Kailbelt generation scenario:
-Existing system plus committed aaditions, as of January, 1993:
Coal-fired steam:
Natural gas GT:
Oil GT:
Diesel:
Natural gas CC:
Hydropower:
Total
59 f'IIW
452 MW
140 MW
67 MW
317 MW
155 MW
1,190 MW
-System additions (1993-2009):
Co a 1-fired steam:
Natural gas GT:
2-5
800 MW
630 MW
-System as of 2010 (accounting for retirements and additions):
Coal-fired steam:
Natural gas GT:
0 i 1 GT:
Diesel:
Natural gas CC:
Hydropower:
Total
813 MW
746 MW
0 IYlW
6 MW
317 MW
155 MW
2,037 MW
The coal-fired steam additions assumed two 200 MW plants at Beluga
in 1993-94, one 200 MW plant near Nenana in 1996, and a third 200
MW plant at 13eluga in 2007. The costs associated with the Beluga
development are based on the opening of that coal field for com-
mercial development, which is by no means a certainty. A number
of environmental problems require resolution before such develop-
ment can take place.
Two alternatives which Battelle included in their base plan which
have not been included in this plan are the Chakachamna and Alli-
son Creek hydroelectric plants. The Chakachamna plant is cur-
rently the subject of a separate feasibility study by the Power
Authority. The current plan would develop a 330 MW plant at a
cost of $1.45 billion at January, 1982 price levels. Further sen-
sitivity studies have confirmed that scenarios involving the
Chakachamna development show some reduction in cost. However this
alternative was not included in the non-Susitna plan due to envi-
ronmental impact and cost uncertainties.
2.5 -Susitna Basin
An assessment of the physical and biological environment of the Susitna
kiver Basin has been made on the basis of available information and
studies conducted under the current study. The climate of the Susitna
Basin is generally characterized by cold, dry winters and warm, moder-
ately moist summers. The upper basin above Talkeetna is dominated by
continental climatic conditions, the lower basin falling within a zone
of transition between maritime and continental climatic influences.
(a) Hydro 1 ogy
Precipitation in the basin varies from low to moderate amounts at
lower elevations to heavy in the mountains. At Talkeetna Station,
at elevation 345, the average annual precipitation is about 28
inches and average snowfall is about 106 inches. At elevations of
about 3000 feet in the Talkeetna mountains, over 80 inches of pre-
cipitation are estimated. About 68 percent of Talkeetna precipi-
tation occur during \Ylay through October. Mean daily temperatures
at the Watana site during the study period varied from -36.7°C in
December to 23.9°C in July.
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The longest period of available Susitna River streamflow data is
for the station at Gold Creek (32 years from 1949 to 1981). At
other stations, record length varies from 6 to 23 years. Gaging
was cant inued at all these stat ions as part of the current pro-
gram. A gaging station was established at the Watana damsite in
1980, and streamflow records are available for the study period.
Using the avail able records, average annual flows at the Watana
and Devil Canyon damsites are computed as 7,943 cfs and 9,042 cfs,
respectively.
Above its confluence with the Chulitna River, the Susitna contri-
butes approximately 20 percent of the mean annual flow measured at
Susitna Station near Cook Inlet. At Gold Creek, the average
winter and summer flows are 2,100 and 20,250 cfs, respectively,
i.e., a 1 to 10 ratio. Approximately 88 percent of the streamflow
recorded at Gold Creek station occurs during the summer months.
The lowest annual flow at Gold Creek was observed in the Water
Year 1969 with an average flow of 5,560 cfs. The return period of
such an event is estimated at about 1 in 10,000 years.
A monthly simulation of the proposed reservoirs and power develop-
ment has been carried out to estimate energy potential of the pro-
posed reservoirs. The critical low flow sequence for energy gen-
eration was observed to be the 32-month peri ad between October,
1967 and May, 1970. The sequence comprises the lowest annual flow
year described above and has a frequency of 1 in 300 years. The
results of the analysis have been used to determine dependable
energy potential of the proposed reservoirs.
( i) F 1 oods
The most common causes of floods in the Susitna River Basin
are sno\'tmelt and/or rainfall over a large area. Annual
maximum peak discharges generally occur between May and
October, usually in June. Some flood peaks have also oc-
curred in August or later and are the result of heavy rains
over large areas augmented by significant snowmelt from
higher elevations and glacial runoff.
For design of spillway faciJities, a regional flood peak
and volume frequency analysis was carried out using there-
corded floods in the Susitna River and its principal tribu-
taries. These analyses are also important for planning the
design of cofferdams for river diversion during the con-
struction phase of the project when ice jamming could also
occur. Mean annual, 50-, 100-, and 10,000-year floods at
Watana and Devil Canyon damsites range from 12,600 cfs to
165,000 cfs at Devil Canyon and from 48,000 cfs to 200,000
c fs at Watana.
2-7
The proposed reservoirs at Watana and Devil Canyon would be
classified as 11 large 11 and with 11 high hazard potential,. ac-
cording to the guidelines for safety inspection of dams
established by the COE. This would indicate the need for
the probable maximum flood (PMF) to be considered in the
evaluation of the proposed projects. Estimates of the PMF
in the Susitna River at several locations, including the
proposed damsites, were carried out by the COE. A reeva1u-
at ion of the PMF in the bas in was undertaken based on a
more comprehensive climatological data base and refined
basin modeling parameters resulting in peak inflows of
326,000 cfs at Watana and 366,000 cfs at Devil Canyon.
(ii) River Ice
The Susitna River usual1y starts to freeze by 1ate October.
River ice thickness and strength vary according to the
river channel shape, slope and discharge. The maximum
thicknesses observed at selected locations on the river
vary from 3.2 feet at Gold Creek to 23.0 feet at Devil
Canyon. Ice breakup in the river commences by late April
or early May; ice jams occasionally occur at river con-
strictions, resulting in rises in the water level of up to
20 feet.
(iii) River Morphology and Sediment Yield
Suspended sediment data have been collected for several
years by th~ USGS at 13 stat ions on the Sus itna and its
tributaries. At Gold Creek Station, 22 years of data are
available. Most of the suspended sediment is transported
in June through September. Bed load data for the river and
its tributaries are extremely limited. Estimated annual
transport of suspended materials at the Gold Creek gag·ing
stations is 7.7 million tons. Trap efficiencies for the
proposed reservoirs at Watana and Devil Canyon, based on
literature surveys of worldwide experience under simi1ar
glacial river basins, are estimated at 70 to 100 percent.
Estimated sediment deposition in the reservoirs is up to
472,000 acre feet in Watana in 100 years or 5 percent of
gross reservoir volume, and up to 155,000 acre feet (14.2
percent) at Devil Canyon in 100 years.
Preliminary studies of the morphology of the river below
the proposed dams have been made to evaluate potential
changes caused by the post-project flow regime. The study
indicates that significant changes in the lower river mor-
phology are unlikely to be caused by the projects pro-
posed.
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(b)
(c)
Regional Geology
The geologically complex Talkeetna Mountain area has a history of
at least three periods of major tee tonic deformation. The o 1 des t
rocks exposed in the region are volcanic flows and limestones (250
to 300 million years before present) which are overlain by sand-
stones and shales (150 to 200 m.y.b.p). A tectonic event approxi-
mately 135 to 180 m.y.b.p. resulted in the intrusion of large dio-
rite and granite plutons, which caused intense thermal metamor-
phism. 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 period (65
to 100 m.y.b.p.). As a result of this faulting and uplift, the
eastern portion of the area was elevated, and the oldest volcanics
and sediments were thrust over the younger metamorphics and sedi-
ments.
The diorite pluton that forms the bedrock of the Watana site was
intruded into sediments and volcanics about 65 m.y.b.p. The ande-
site and basalt flows near the site may have been formed immedi-
ately 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 rocks. During the last
several million years, at least two alpine glaciations have carved
the Talkeetna Mountains into the ridges, peaks, and broad glacial
plateaus seen today. Postglacial uplift has induced and is still
causing downcutting of streams and rivers, resulting in the 500-
to-700 foot deep V-shaped canyons that are evident today, particu-
larly at the Vee and Devil Canyon damsites. This continuing ero-
sion has removed much of the glacial debris at higher elevations
but very little alluvial deposition has occurred. The resulting
landscape consists of barren bedrock mountains, glacial till-
covered plains, and exposed bedrock cliffs in canyons and along
streams. The arctic climate has retarded development of topsoil.
Seismicity
A two year study of seismicity of the project area was undertaken
to identify faults that have the potential for surface rupture
within the project area and to provide a basis for estimates of
earthquake ground motions to be considered for dam design. The
project 1 ies within the Talkeetna Terrain, a part of the North
American Plate. The Terrain boundaries are denoted by the Denali-
Totschunda fault to the north and east, the Castle Mountain fault
to the south, a broad zone of deformation with volcanoes to the
west, and the Benioff Zone at depth. The study has indicated that
the Talkeetna Terrain is a relatively stable tectonic unit with
major strain release occurring along its boundaries, but no evi-
dence of faults with recent displacement within those boundaries.
2-9
The Talkeetna Terrain boundary faults were therefore identified as
potential seismic sources. Because of their distance from the
sites, these faults do not have the potential for rupture through
the sites. A total of 13 features identified and investigated in
some detail near the damsites as potential seismic sources, were
found to show no evidence of recent displacement. These features,
therefore, were not considered to be potential seismic sources
that could cause seismic ground motions at the sites or surface
rupture through-the sites. There is considerable worldwide evi-
dence that earthquakes up to a given magnitude could occur on
faults at depth with no detectable evidence of recent displacement
at the ground surface. Such earthquakes have been designated as
"Terrain earthquakes" (or "detection level earthquakes"). The
magnitude of the Terrain earthquake varies according to the degree
of natural preservation of fault-related geomorphic features and
from one tectonic environment to another.
To establish a basis for estimating ground motions at a specific
site, and hence to design the structures to be bunt, estimates
were made of magnitudes for the maximum earthquakes in the region
associated with the potential earthquake sources. The maximum
earthquake (ME) magnitude, closest approach and important mean
peak ground accelerations were estimated for boundary faults and
for the Terrain earthquake as follows:
Dev i 1 Canton Watana
ME m i 1 es acce 1. miles accel.
Source l!:!sl lg) (g)
Castle Mountain 7-1/2 71 65
Denali Fault l::l 40 0.2 43 0.2
Benioff Zone (interplate) 8-1/2 57 0.35 39 0.3
l)enioff Zone (intraplate) 7-1/2 31:3 39
Terrain Earthquake 6-1/4 <6 0.55 <6 0.55
Work undertaken by Dr. L. Sykes of the Lamont Doherty Institute,
New York, suggests that the magnitude of the Terrain earthquake
could be as high as 6-1/4 to 6-1/2.
The studies concluded that there would be a high likelihood for
reservoir induced earthquake as a result of impoundment. However,
such an event is not expected to cause an earthquake larger than
that which could occur in a given region "naturally."
(d) Water Use and Quality
Water rights in Alaska are administered by the Alaska Department
of Natural Resources (UNR). The mainstem Susitna corridor encom-
passes 30 townships from the proposed impoundment area downstream
to the estuary. Existing surface and ground water appropriations
are primarily for single-family and multi-family homes, the
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greatest usage occurring during summer months for irrigating
lawns, gardens, and crops. There are only five areas where water
appropriations are located within one mile of the mainstem Susitna
River. No surface water diversions are recorded that draw water
directly from the Susitna River or its adjoining side channels and
sloughs.
The Susitna River is a fast-flowing, cold-water stream of the cal-
cium bicarbonate type containing soft-to-moderately hard water.
The temperature remains at or near 32°F during winter, and in sum-
mer the maximum is 55°F. Dissolved oxygen concentrations typi-
cally remain near the saturation level, always exceeding 80 per-
cent but averaging near 100 percent in the summer. Typically, pH
values range between 7 and 8 and exhibit a wider range in the sum-
mer as compared to the winter. True color, resulting from tundra
runoff, displays a wider range during summer than winter. The
concentrations of many trace elements monitored in the river were
low or within the range characteristic of natural waters with few
exceptions, as were concentrations of organic pesticides and herb-
icides, uranium, and gross alpha radioac!ivity.
(e) Fisheries Resources
Both resident and anadromous fish occur in the Susitna River sys-
tem. Resident fish species are grayling, burbot, rainbow trout,
Dolly Varden, three spined stickleback, lognose sucker, slimy
sculpin, whitefish, and lampreys. Anadromous fish are sockeye,
pink, coho, chinook, and chum salmon and eulachon. Arctic gray-
ling and rainbow trout, the primary resident game species, occur
near tributary mouths during the summerrmonths and in the mainstem
Susitna during winter. Both species use the mainstem of the
Susitna as a migratory corridor for moving between rivers and
streams. Spawning likely occurs in the clearer tributaries.
Salmon utilize the Susitna River and its tributaries below Devil
Canyon as a spawning habitat. Data indicate that physical bar-
riers prevent salmon from migrating upstream of Devil Canyon.
Salmon migration begins in late spring and continues into the
fall. Studies to date indicate that the run of chinook salmon
through the area above the confluence of the Chulitna and Tal-
keetna Rivers begins around mid-June. Pink salmon arrive in this
region during late July and chum salmon migrate through in August
and early September. Sockeye salmon appear in July and August.
Following deposition in the fall, the eggs hatch in the spring.
The young salmon, depending on the species and a variety of un-
known factors, either migrate to the sea within a few months or
remain in the river for one or two years before migrating down-
stream.
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(f) Wildlife Resources
Species of big game which inhabit the upper Susitna basin are:
black and brown bear, wolf and wolverine, Dall sheep, caribou, and
moose.
Black bear distribution in Alaska coincides with the presence of
forest habitat. Thus, within the Susitna basin most black bear
are found in steep terrain along the river and its tributaries.
Brown bear occur primarily in open tundra and grassland areas.
Preliminary estimates of brown bear numbers in the study area is
1 bear per 19 mi2, indicating 3 to 4 bears in the area to be
flooded.
One known and 5 to 6 suspected wo 1f packs occur in the area that
would be most directly affected by the 2 reservoirs. The esti-
mated total population is between 40 and 80 animals. Wolf control
operations have been conducted in the past, with the 1 atest such
activity occurring in 1978.
Wolverine are also present and are found in all habitat types.
Their distribution appears to be related to prey availability,
concentrating in hilly areas above treeline in the summer and
fall, and in lower elevations during winter and early spring.
Three populations of Dall sheep occur in the Upper Susitna Basin:
the Watana hills herd, Watana-Grebe Mountain herd and the Portage-
Tsusena Creek herd. A mineral lick in the Jay Creek area appears
to be an important area for the Watana hills herd. Sheep were
frequently observed utilizing the lick, which will be partially
inundated by the Watana reservoir.
The Nelchina caribou herd occupies an area of approximately 20,000
square miles in Alaska. This large range can be divided into 16
sub-ranges, including the Upper Susitna Basin. Portions of the
Upper Susitna Basin have been consistently used throughout the
years by large portions of the herd, with most use taking place in
summer, fall, and late winter. During some years, the entire
herd, currently numbering 20,000 animals, has used the Upper
Basin. A small subherd of approximately 1,000 an-imals appears to
be residing permanently in the upper portion of the basin.
Moose populations upstream from the proposed impoundment areas
were studied in 1980 and 1981. Although the physical condition of
the moose appeared to be deteriorating, the habitat is not be-
lieved to be at its carrying capacity. Moose generally moved to
lower elevations during late spring and early summer, then back to
higher elevations in late summer and winter. The majority of
moose observed were in conifer and shrubland habitat. A winter
census of the impoundment area showed 28 moose in the Devil Canyon
impoundment and 42 within the Watana impoundment. This is
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believed to be lower than normal because of a mild winter. Moose
are also present in the Susitna River Basin downstream from the
Devil Canyon damsite, consisting of both resident and migratory
populations. No specific calving areas were located during these
studies, but it appears that females use river islands to calve.
During winters of heavy snowfall, moose tend to migrate to the
river bottoms.
The major furbearer species inhabiting the project area include
red fox, coyote, lynx, mink, pine marten, river otter, short-
tailed weasel, least weasel, muskrat and beaver. Red fox and pine
marten are the most heavily trapped of the species; coyote and
lynx are not common in the area.
A total of 132 species of birds were recorded in the Upper Susitna
River Basin study area. The most abundant species are common red-
poll, savannah sparrow, white crowned sparrow, lapland longspur,
and tree sparrow. Fourteen species are rare in the region but are
found in larger populations in other areas of Alaska.
Ten golden eagle, 6 bald eagle, and 4 common raven nests are lo-
cated within the study area, while 2 bald eagle and 4 golden eagle
nests occur within the impoundment zone. No endangered species
(the bald eagle is not endangered in Alaska) are known to occur in
the study area.
Sixteen species of small mammals are found in the upper Susitna
Basin, the most abundant being the northern red-backed vole and
the masked shrew. Arctic ground squirrels are abundant in well-
drained tundra habitats throughout the high country. Collared
pika and hoary marmots are relatively common in rock habitats
above the treeline. Red squirrels and porcupine are found in
forests and woodland habitats.
(g) Botanical Resources
The Upper Susitna River Basin is located in the Pacific Mountain
physiographic division in south-central Alaska. Many areas along
the river in the upper basin are steep and covered with conifer-
ous, deciduous, and mixed coniferous and deciduous forests. Flat
benches occur at the tops of these banks and usually contain low
shurb or woodland conifer communities. Low mountains rise from
these benches and are covered by sedge-grass tundra and mat and
cushion tundra. The major vegetation/habitat types found in the
upper river drainage are low-mixed shrub, woodland and open black
spruce, sedge-grass tundra, mat and cushion tundra, and birch
shrub.
Below Devil Canyon, vegetation/habitat consists primarily of
mature ·and decadent cottonwood forests, birch-spruce forest, alder
thickets, and willow-cottonwood shrub communities. The willow,
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cottonwood shrub and alder communities are the earliest to estab-
1 ish on new grave 1 bars, to 11 owed by cottonwood forests, and,
eventually, birch-spruce forest. Wetland areas, ponds, and 1 akes
are present only in limited amounts within the impoundment area.
No plant species occurring in Alaska are listed as endangered by
federal or state authorities. None of the species under consider-
ation for listing were found in the project area.
(h) Historic and Archaeological Resources
A total of 43 archaeological sites, and three historic sites are
1 ocated within the area to be affected either directly or in-
directly by the Watana Dam impoundment. The archaeological sites
represent human occupation dating from approximately 10,000 B.C.
in the following culture periods: American Paleoarctic, Northern
Archaic Tradition, Arctic Small Tool Tradition, Late Prehistoric
Athapaskan, and Historic. The historic sites are all cabins built
·in the 1920s.
The Devil Canyon impoundment area includes seven archaeological
sites discovered during this study. These sites, representing
various time periods in Alaska prehistory i.ncluding the American
Paleoarctic and the Northern Archaic Tradition. One historic
site, also a cabin believed to be constructed in the 1930s, lies
within the Devil Canyon impoundment area.
(i) Socioeconomics
The state of Alaska has experienced steadily increasing population
since the 1940s, with accelerated growth during the 1970s. Cur-
rent population is approximately 400,000, with approximately 50
percent located in the greater Anchorage area. The RaiJbelt re-
gion of Alaska contained 70 percent of the state 1 ~ population, or
approximately 285,000 people, in 1980. This is an increase from
200,230 in 1970. Employment in Alaska and the Railbelt rose
dramatically during the construction of the Trans-Alaska Pipeline
System and has since leveled off.
Increases in population between 1970 (6,500) and 1980 (18,000) in
the Matanuska-Susitna Borough (175 percent) were far higher than
the state average. Population levels stabiJized as the. Trans-
Alaska Pipeline was completed. Most of these people reside in the
southern quarter of the Borough. Palmer and Wasilla are the larg-
est communities, with populations of approximately 2,100 and
1,550, respectively. Other population centers in the Borough are
Big Lake, Eska-Sutton, Houston, and Talkeetna. Virtually all em-
ployment in the Mat-Su Borough is government, service, and support
sector oriented. Total employment has risen steadily from 1,145
in 1979 to 3,078 in 1979, an .increase of 169 percent. However,
the Borough consistently has had high unemployment rates, often
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( k)
the highest in the state. The Borough is more dependent on seas-
onal employment than larger population centers such as Anchorage.
Recreational Resources and Land Use
Recreational activities currently available in the Upper Susitna
Basin are those associated with undeveloped facilities. Hunting,
fishing, hiking, and camping are the primary recreational uses,
along with boating on the lakes. There are no areas in the vicin-
ity of the project that are included or designated for inclusion
in the National Wild and Scenic River System, the National Trails
System, or a federal or state wilderness area.
Existing land use in the area is typical for that of interior un-
developed Alaska. Broad expanses of wilderness areas are present
with minimal man-made developments or structures, and access is
severely restricted. A small number of inhabited structures are
found near Portage Creek, High Lake, Gold Creek, Stephan Lake,
Clarence Lake, and Big Lake. There is little land management in
the area. Most land in the project area and directly south has
been selected by native corporations under provisions of the
Alaska Native Claims Settlement Act; lands to tne north are gener-
ally managed by the U.S. Bureau of Land Management.
Aesthetic Resources
The Upper Susitna River Basin is a wilderness region comprising a
diverse landscape composite, roadless and relatively uninhabited.
The combination of these factors creates a large region that is
aesthetically renowned for its natural beauty. The deeply cut
canyons and gorges of the Susitna Riyer scenically exhibit the
river's extraordinary power; the gorges are particularly striking
at Devil and Vee Canyons where turbulent rapids, rock outcroppings
and cliffs, and enclosed walls dominate the scene. Positioned be-
tween the two major population centers of Fairbanks and Anchorage,
the area's aesthetic resources are important, but not outstanding
compared with other areas in the state.
2.6 -Susitna Basin Development Selection
A number of engineering and planning studies were carried out during
the early phases of the project feasibility assessment as a basis for
formulation of Susitna Basin development plans and selection of the
preferred plan. The recommended Watana/Devi 1 Canyon dam project was
compared to alternative methods of providing the Railbelt energy needs
including thermal and other potential hydroelectric developments out-
side the Susitna Basin on the basis of technical, economic, environ-
mental, and social aspects.
2-15
(a) Damsite Selection
In previous Susitna Basin studies, twelve damsites were identified
in the upper portion of the basin, i.e., upstream from Gold Creek.
Preliminary assessments of these sites, on the basis of published
data, showed that three sites, Devil Canyon, High Devil Canyon,
and Watana are potentially the most economic large energy pro-
ducers in the basin. Sites such as Vee and Susitna III have only
medium energy production, and are slightly more costly. 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.
A screening process was used to eliminate sites which would obvi-
ously not feature in the initial stages of a Susitna Basin devel-
opment plan. This screening was based on consideration of envi-
ronmental factors and the relative merits of each site in terms of
economic energy contribution. The seven sites remaining after
this screening were:
-Devil Canyon;
-High Devil Canyon (Susitna I);
-Watana;
-Susitna III;
-Vee;
-Mac l aren; and
-Den a l i .
Preliminary construction cost estimates were developed for devel-
opments at each site. The relative cost differences between rock-
fill and concrete dams at the sites are generally marginal or
greatly in favor of the rockfill. Rockfill dams were therefore
assumed at all developments for general consistency. These esti-
mates, together with energy production estimates, provided a basis
for conceptualization of basin development plans.
(i) Devil Canyon
The Devil Canyon dam was assumed to consist of a rockfi ll
dam, single spillway, power facilities incorporating an
underground powerhouse, and a tunnel diversion located at
the upper end of the canyon at its narrowest point. The
675-foot-high central core rockfill dam will rise above the
valley on the left abutment and terminate in an adjoining
saddle dam of similar construction. The gated overflow
spillway structure will be located on the right bank to-
gether with a concrete-1 ined chute and intermediate and
terminal stilling basins. The power facilities will be
located underground on the right abutment. The massive
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intake structure will be founded within the rock at the end
of a deep approach channel and will consist of four i nte-
grated units, each serving individual tunnel penstocks.
The powerhouse will house four 150 MW turbine generators.
A staged powerhouse alternative was also investigated. The
dam would be completed to its full height but with an ini-
tial plant installed capacity of 300 MW. The complete
powerhouse would be constructed together with penstocks and
a tailrace tunnel for the initial two 150 MW units, to-
gether with concrete foundations for the future units.
( i i ) Wat an a
For initial comparative study purposes, the dam at Watana
was assumed to be a 63-million-cubic-yard, central-core
rockfill structure, 880 feet high, located on a similar
alignment to that proposed in the previous COE studies.
The right bank spillway will be similar in concept to that
at Devil Canyon with an intermediate and _terminal stilling
basin. The underground power facilities located within the
left abutment with similar intake, underground powerhouse,
and water passage concepts to those at Devil Canyon will
incorporate four 200 MW turbine/generator units giving a
total output of 800 MW.
(iii) High Devil Canyon
This site is located between Devil Canyon and Watana. The
855-foot-high, 48-million-cubic-yard rockfill dam will be
similar in design to Devil Canyon. The left bank sp-illway
and the right bank powerhouse facilities will also be simi-
lar in concept to Devil Canyon, with an installed capacity
of 800 MW.
(iv) Susitna III
( v)
The development will comprise a 55 million cubic yard rock-
fill dam with an impervious core approximately 670 feet
high. A concrete-lined spillway chute and a single still-
ing basin and will be located on the right bank. A power-
house of 350 I~W capacity will be located underground and
the two diversion tunnels on the left bank.
Vee
A 610-foot-high, 10-million-cubic-yard rockfill dam was
considered at this site together with a spillway utilizing
a gated overflow structure, chute, and flip bucket. The
400-MW underground power facilities will be located in the
left bank with a tailrace outlet well downstream from the
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main dam. A rockfill saddle dam will also be required.
Two diversion tunnels will be provided on the right bank.
(vi) Maclaren
This development will consist of a 185-foot-high earthfill
dam founded on pervious riverbed materials. The reservoir
will essentially be used for regulating purposes. Diver-
sion will be through three conduits located in an open cut
on the left bank and floods will be discharged via a side
chute spillway and stilling basin on the right bank.
(vii) Denali
Denali is similar in concept to Maclaren with no generating
facilities. The dam will be 230 feet high and of earthfill
construction. A combined diversion and spillway facility
will be provided by twin concrete conduits founded in open
cut excavation in the right bank and discharging into a
common stilling basin.
(viii) Staged Developments
Staged developments were also considered at Devil Canyon,
Watana, and High Devil Canyon. In these cases, initial
partial completion of dam and power facilities was evalu-
ated with later expansion to the complete development.
(c) Development Plan Formulation
Basin development plans involving appropriate combinations of the
seven sites were formulated. A computer assisted screening pro-
cess identified the plans that are most economic as those of Devil
Canyon/Watana or High Devil Canyon/Vee. In addition to these two
basic development plans, a tunnel/Watana dam scheme was intro-
duced. This provides potential environmental advantages to the
Devil Canyon/Watana scheme by replacing the Devil Canyon dam with
a long power tunnel.
(i) Initial Screening
The most important conclusions drawn from this screening
are as follows:
-For energy requirements of up to 1, 750 GWh, the High
Devil Canyon, Devil Canyon or the Watana sites individ-
ually provided the most economic energy.
-For energy requirements of between 1,750 and 3,500 GWh,
the High Devil Canyon site is the most economic.
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-For energy requirements of between 3,500 and 5,250 GWh
the combinations of either Watana and Devil Canyon or
High Devil Canyon and Vee are the most economic.
-The total energy production capability of the Watana/
Devil Canyon developments 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 6,000
GWh range.
Tunnel Alternative
A scheme involving a long power tunnel could conceivably be
used to replace the Devil Canyon dam as a second stage of
the Watana/Devil Canyon development plan. It couid develop
comparable head for power generation and may provide some
environmental advantages by avoiding inundation of Devil
Canyon. Conceptually, the tunnel alternatives would com-
prise 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 1 ~ 200 MW;
-A reregulation dam if the intake works are located down-
stream from Watana; and
Arrangements for compensation flow in the bypassed river
reach.
Of the tunnel schemes considered, an alternative was se-
lected involving two 30-foot-diameter tunnels 13.5 miles
long. This scheme~ which includes a 245-foot high reregu-
lating dam downstream from Watana; and a total installed
capacity of 1,180 MW, is jud·ged to be the environmentally
and economically superior alternative.
(iii) Final Screening
The final plan screening process indicated that the Watana/
Devi 1 Canyon and the High Oevi l Canyon/Vee plans are clear-
ly superior to all other dam combinations. ln addition,
plans involving the tunnel scheme as an alternative to the
Devil Canyon dam and a plan combining a Watana/High Devil
Canyon/Portage Creek combination were also formulated for
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more detailed evaluation. Four basic plans were estab-
1 ished as a result of this process. Plan 1 involves the
Watana-Dev·il Canyon sites, Plan 2 the High Devil Canyon-Vee
sites, Plan 3 the Watana-tunnel concept, and Plan 4 the
Watana-High Devil Canyon sites.
(d) Development Plan Selection
Selection of the development plan was based on a final considera-
tion of the economic, environmental, social and energy contribu-
tion attributes of each alternative. A preliminary evaluation of
plans was initially undertaken to determine broad comparisons of
the available alternatives. This was followed by appropriate ad-
justments to the plans and a more detailed evaluation and compari-
son.
Some additional economic benefits are gained if the Chakachamna
hydroelectric project is constructed instead of the Vee dam.
The results of the Watana tunnel comparison indicated that the
tunnel scheme versus the Devil Canyon dam scheme adds approxi-
mately $680 million to the total system present worth cost. A
sensitivity analysis made to determine the effect of halving the
tunnel costs indicated that the tunnel scheme is still more costly
then constructing the Devil Canyon dam.
The plans with the lowest present worth cost were also subjected
to further sensitivity analyses to assess the economic impacts of
various load growths. The results for low load forecasts illus-
trate that the most viable Susitna t3asin development plan is the
Watana-Devil Canyon plan with a capacity of 800 MW which has a
present worth cost of $210 mil lion less than its closest competi-
tor, the High Devil Canyon-Vee plan. For the high load forecasts,
the results indicated that the economic advantage of the Watana/
Devil Canyon plan improves significantly.
For the remaining three Plans 1, 2, and 3 a final evaluation pro-
cess was conducted in a series of steps. At each step, two plans
are compared. The superior plan is then passed on to the next
step for evaluation against a. third plan, and so on.
(i) Devil Canyon Dam Versus Tunnel
The first step in the process involved the comparison of
the Watana-Devil Canyon dam plan and the Watana-Tunnel
plan. Since Watana is common to both plans, the evaluation
was based on a comparison of the Devil Canyon dam and pre-
ferred tunnel alternative. From an economic point of view,
the Watana-Devil Canyon dam scheme is superior. Considera-
tion of the sensitivity of the basic economic evaluation to
potential changes in capital cost estimate and other
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economic parameters did not change the basic economic
superidrity of the dam scheme over the tunnel scheme.
In the environmental comparison of the two schemes, the
tunnel scheme was judged to be superior. In terms of im-
pact on state and local economics and risks because of
seismic exposure, the two schemes are rated equal. How-
ever; the dam scheme has a greater potential for energy
production, develops a larger portion of the basin•s poten-
tial, and displaces a larger arnount of non-renewable energy
resources.
Overall, the estimated cost saving of $680 million in favor
of the dam scheme plus the additional energy produced are
considered to outweigh the reduction in the overall envi-
ronmental impact of the tunnel scheme. The dam scheme is
therefore judged to be superior.
(ii) Watana-Devil Canyon Versus High Devil Canyon-Vee
The second step in the development selection process in-
volved an evaluation of the Watana-Devil Canyon and the
High Devil Canyon-Vee development plans. In terms of the
econdmic criteria the Watana-Devil Canyon plan is less
costly by $520 million. Consideration of the sensitivity
of this decision to potential changes in the various para-
meters considered did not change the basic superiority of
the Watana-Devil Canyon Plan.
In assessing these plans environmentally, a reach-by-reach
comparison was made for the section of the Susitna River
between Portage Creek and the Tyone River. The Watan a-
Devil Canyon scheme would create more potential environ-
mental impacts in the Watana Creek area. However, the po-
tential environmental impacts above the Vee Canyon dam with
a High Devil Canyon-Vee development were judged to be more
severe.
In terms of energy contribution criteria, the Watana-Devil
Canyon scheme was assessed to be superior because of its
higher energy potential and the fact that it develops a
higher proportion of the basin•s potential. In terms of
the social criteria, the Watana-Devil Canyon plan was
judged to have a slight advantage over the High Devil
Canyon-Vee plan. This is because of its greater potential
for displacing nonrenewable resources.
Overall, the Watana-Devil Canyon plan is thus considered to
·be generally superior for all the evaluation criteria.
This plan was therefore selected as the preferred Susitna
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Basin development plan, as a basis for continuation of more
detailed design optimization and environmental studies.
2.7 -Susitna Hydroelectric Development
The conclusion of the development selection studies was that the hydro-
electric potential of the Susitna Basin should be tapped by installa-
tion of power plants and related facilities at the Watana and Devil
Canyon sites. The Power Authority recommended to the governor in March
1981 that further study of these sites be undertaken.
As originally conceived the Watana project initially comprised an
earthfill dam, crest elevation 2225 feet and 400 MW of generating ca-
pacity to commence operation in 1993. An additional 400 MW would be
brought on-line in 1996. At Devil Canyon an additional 400 MW would be
installed to commence operation in the year 2000. Detailed studies of
each project have led to refinement and optimization of designs in
terms of a number of key factors including updated load forecasts and
economics. Geotechnical and environmental constraints identified as a
result of continuing field work have also greatly influenced the cur-
rently recommended design concepts.
(a) Watana Project Formulation
The Watana Project as proposed in the recommended development sel-
ection has been further refined in the context of updated load
forecasts and geotechnical and environmental investigations. The
project will still comprise an earthfill dam with appropriately
sized spillway, diversion, emergency release, and power generation
facilities at the Watana site.
(i) Selection of Reservoir Level
The selected elevation of the Watana dam crest is based on
considerations of the value of the hydroelectric energy
produced from the associated reservoir, geotechnical con-
straints on reservoir levels, and freeboard requirements.
Economic comparisons of reservoir levels were made on the
basis of firm and average annual energy produced by the
Susitna development for a range of levels within appropri-
ate drawdown and downstream flow constraints. These com-
parisons indicated total system costs to be relatively in-
sensitive to dam height. From an economic standpoint, the
optimum crest elevation could be considered as varying over
a range of reservoir elevations from 2,140 to 2,220 feet
with little effect on project economics. The governing
factors in establishing the upper limit of dam height were
consequently geotechnical considerations relative to the
re.l ict channel.
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Geological conditions in the relict channel area are not
fully known at this time. Nevertheless, reservoir 1evels
above 2185 feet would 1 ead to increased saturation of
in situ materials and could give rise to potentially more
severe settlement, seepage and seismic instability prob-
lems. Costly as any remedial measures might be, an element
of uncertainty would sti 11 remain as to their effective-
hess. It was therefore determined that with a normal res-
ervoir level of 2185 and a small freeboard dike the
following conditions should be met:
-For floods up to the 1:10,000-year occurrence there would
be no danger of overtopping the lowest point in the
relict channel.
-For the PMF a freeboard dike in the low area of up to 10
feet in height would provide .adequate protection. This
dike would be wetted only a few days during a PMF event.
-If seismic settlement or settlement because of permafrost
melting were to occur, the combination of the 10-foot
freeboard dike constructed on-a suitable foundation plus
a normal reservoir level of 2185 feet would ensure that
breakthrough in the relict channel would not occur.
Within this approach, the Wataha project will develop the
maximum energy reasonably available without incurring the
need for costly water retaining structures in the relict
channel area. The normal maximum operating level of the
reservoir was therefore set at Elevation 2185, which also
maximizes the economic use of the Susitna resource.
(ii) Selection of Installed Capacity
The generating capacity to be installed at both Watana and
Devil Canyon was determined on the basis of generation
planning studies, together with appropriate consideration
of the following:
-Available firm and averag~ energy from Watana and Devil
Canyon;
-The forecast energy demand and peak load demand of the
system;
-Available firm and average energy from other existing and
committed plants;
-Capital cost and annual operating costs for Watana and
Devil Canyon;
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-Capital cost and annual operating costs for alternative
sources of energy and capacity;
-Environmental constraints on reservoir operation; and
-Turbine and generator operating characteristics.
The required total capacity at Watana in a wet year, based
on the Battelle medium load forecast, varies between 800 MW
in 1993 and 874 MW in the year 2000, excluding standby and
spinning reserve capacity. With Devil Canyon on-1 ine, the
capacity requirement varies from 660 MW in 2002 to 900 MW
in 2010. On the basis of this evaluation, the ultimate
power generation capability at Watana was selected as 1020
MW for design purposes, to allow a margin for hydro spin-
ning reserve and standby for forced outage. This installa-
tion also provides a low cost margin in the event that the
load growth exceeds the Battelle med i urn load forecast.
Considerations of improved plant efficiency and security of
operation provided by a larger number of smaller capacity
units led to adoption of a scheme incorporating six units
each with a rated capacity of 170 MW
(iii) Selection of Spillway Design Floods
Normal design practice and applicable regulations for proj-
ects for this magnitude require that the project be capable
of passing the PMF routed through the reservoir without en-
dangering the dam. In addition to this requirement, the
project should have sufficient spillway capacity to safely
pass a major flood of lesser magnitude than the PMF without
damaging the main dam or ancillary structures. The flood
frequency analysis produced the following values:
Flood
Probable Maximum
Spillway design
Frequency
1:10,000
Inflow Peak
326,000 cfs
156,000 cfs
Additional capacity required to pass the PMF will be pro-
vided by an emergency spillway consisting of a fuse plug
and rock channel cut on the right bank.
(b) Watana Scheme Development
A number of studies were undertaken to consider alternatives and
select appropriate configurations for the Watana dam, diversion,
spillway, and power facility arrangements.
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(i) Main Dam Alternatives
Previous studies by the COE envisaged an embankment dam at
Watana. Initial studies completed as part of this current
evaluation included comparison of an earthfill dam with a
concrete arch dam at the Watana site. The cost of the em-
bankment dam was found to be somewhat lower than the arch
dam, and there were no significant advantages to be gained
in project layouts or schedule by constructing the concrete
arch. The arch dam alternative was therefore eliminated
from further consideration.
The Watana dam is the central and most costly component of
this project. Selection of the configuration of the em-
bankment dam cross-section required consideration of:
The availability of suitable construction materials with-
in economic haul distance, particularly core material;
-The requirement that the dam be capable of withstanding
the effects of a significant earthquake shock as well as
the static loads imposed by the reservoir and its own
weight; and
-The relatively limited construction season available for
placement of compacted fill materials.
Based on these considerations, the main dam will consist of
a compacted central vertical core protected by fine and
coarse filter zones both upstream and downstream. The up-
stream and downstream supporting fill zones wi 11 contain
relatively free draining compacted gravel or rockfill, pro-
viding stability to the overall embankment structure. Al-
ternative axes of the dam were investigated and optimized
relative to overall project cost. The adopted ax is has a
s 1 i ght curvature downstream at the right abutment. Up-
stream slopes of 2.75H:lV, 2.4H:lV, and 2.25H:lV were also
examined from cost and stability perspectives. The 2.4H:lV
slope was adopted for the recommended project layout. The
downstream slope is 2H:lV.
(ii) Diversion Scheme Alternatives
The topography of the site generally dictates that diver-
sion of the river during construction be accomplished using
diversion tunne 1 s with upstream and downstream cofferdams
protecting the main construction area. The configuration
.of the river and rock conditions in the vicinity of the
site favors location of the diversion tunnels on the right
bank. The recurrence interval of the design flood for di-
version is generally established based on the characteris-
tics of the flow regime of the river, the length of the
2-25
construction period for which diversion is reqiJired, and
the probable consequences of overtopping of the cofferdams.
A 50-year recurrence interval flood of 81,000 cfs was sel-
ected for Watana.
Selection of the arrangement and size of the component fea-
tures of the diversion scheme included consideration of a
number of alternatives. These included concrete-lined
versus unlined tunnels, tunnel size, type of operation and
elevation relative to cofferdam size, and the long-term use
of diversion tunnels for provision of emergency flow-
release facilities from the Watana reservoir. An important
consideration in diversion scheme design is cofferdam clos-
ure. The selected combination of one lower level pressure
tunnel and one free flow tunnel, each 38 feet in diameter,
will permit initial diversion to be made using the lower
pressure tunnel. This will simplify the critical closure
operation and avoid potentially serious delays in the sche-
dule.
(iii) Spillway Alternatives
The project has been designed to safely pass a 1:10,000-
year flood discharge of 145,000 cfs and a PMF of 310,000
cfs. In the evaluation of alternative spillway arrange-
ments, the potential for nitrogen supersaturation of spill-
way discharges was an important consideration. Nitrogen
supersaturation is toxic to fish and could occur when
aerated flows in deep plunge pools or large hydraulic jumps
are subjected to pressures in excess of 30 to 40 feet. Al-
ternatives considered to overcome this problem included
cascade spillways in which flows are discharged over a
series of relatively small steps excavated in rock and the
use of discharge valves to release flood flows less than
the 50-year flood.
Other alternatives considered were main spillway facilities
in various locations, and appropriate combinations of gated
agee-type overflow structures, concrete-1 ined chutes, and
flip buckets and stilling basin to discharge flows into the
river downstream and for energy dissipation. Open channel
emergency spillways with an erodible fuse plug were also
considered for discharge of the PMF. Clearly the selected
spillway type and location will greatly influence and be
influenced by the selected project general arrangement.
The proposed spillway configuration was selected on the
basis of economics, technical feasibility, and environ-
mental constraints. It comprises a 3-gated control struc-
ture, chute, and flip bucket in the right abutment designed
to discharge 115,000 cfs, the remaining 30,000 cfs of the
10,000-year flood being handled through six fixed-cone
valves located underneath the flip bucket.
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An emergency spillway will also be located in the right
abutment with a 30-foot-high erodible fuse plug which will
be overtopped during a Pf.'IF, d i sch arg i ng into the Ts us en a
Creek area.
Power F aci 1 it i es
Studies were undertaken during the development of concep-
tual project layouts at Watana to investigate both right
and left bank and surface and underground locations for
power facilities. The configuration of the site is such
that left bank locations generally require longer penstock
and/or tailrace tunnels in poorer quality rock than exists
on the right abutment. Surface locations are also gener-
ally more expensive and subject to additional operation
limitations because of climatic conditions. An underground
powerhouse was therefore selected and located on the right
bank such that the major openings lie between the two major
shear features ( 11 The Fi ns 11 and the 11 Fi ngerbuster 11
).
It has been conservatively a~sumed that full concrete-
llning of the penstocks and tallrace tunnels will be re-
quired. In practice, it may be possible for a large pro-
portion of the tailrace tunnels to be unlined, depending on
the actual rock quality encountered. For the design head
and specific speed, Francis type turbines having a reason-
ably flat load-efficiency curve over a wide range of rated
output, were selected. The final arrangement comprises six
units producing 170 MW rated at maximum reservoir level in
the peak demand month of December, at full gate. The unit
output at best efficiency and p. rated head of 680 feet is
181 MW. An underground transformer gallery has been sel-
ected for minimum total cost of transformers, cables, bus,
and transformer 1 asses. Sing 1 e-phase transformers are re-
quired because of transport limitations on Alaskan roads
and railways. The selected scheme is an economic grouping
of nine transformers arranged so that each set of three
transformers serves two turbine-generator units.
The power intake and approach channel are significant items
in the cost of the overall power facilities arrangement.
Studies of various configurations resulted in selection of
a preferred penstock arrangement consisting of six individ-
ual 18-foot diameter penstocks. With this arrangement, no
inlet valve is required in the powerhouse since penstock
dewatering can be performed by using the control gate at
the intake.
The preliminary design of the power facilities involves two
tailrace tunnels leading from a common surge chamber .
2-27
Optimization studies were carried out for sizing of all
water passages.
(v) Environmental Constraints
In addition to the potential for nitrogen supersaturation
during spillway operation, major environmental constraints
on the design of the power facilities are:
-Control of downstream river temperatures; and
-Control of downstream flows.
The power intake design is such that power plant flows may
be drawn from the· reservoir at four different levels
throughout the anticipated range of reservoir drawdown for
energy production. This allows control of downstream river
temperatures within acceptable limits.
The Watana development is currently planned to provide max-
imum energy to the Railbelt as closely matched to demand as
possible. For this purpose, the project will be operated
as a daily peaking plant for load follow·ing. The actual
extent of daily peaking will be dictated by unit availabil-
ity, unit size, system demand, system stability, generating
costs, etc. Flow releases during operation of the project
will adversely impact the salmon spawning areas in some
reaches of the river downstream during critical summer
months. Appropriate mitigation measures to compensate for
these impacts are currently under study.
(vi) Selection of Watana General Arrangement
Preliminary alternative arrangements of the Watana Project
were developed and subjected to a comprehensive series of
review and·screening processes. The layouts selected from
each screening process were developed in greater detail
prior to the next review, and where necessary, additional
layouts were prepared combining the features of two or more
of the alternatives. Assumptions and criteria were evalu-
ated at each stage and additional data incorporated as
necessary. The final selection was accomplished on the
basis of technical feasibility, economics, operational and
environmental considerations.
(c) Devil Canyon Project Formulation
Develorxnent selection studies were initially based on a rockfill
dam at Devil Canyon for general consistency of site comparisons.
Studies of the concept of an arch dam at Devil Canyon, as origin-
ally proposed by the USBR and COE, indicated that construction of
such a dam at this location was probably feasible. Formulation of
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project designs at Devil Canyon was therefore essentially based on
this concept. Refinements in the context of updated load
and
were
forecasts, geotechnical and environmental investigations
related spillway, diversion, and power facilities designs
further evaluated for this site.
(i)
( i i)
Selection of Reservoir Level
The selected normal maximum operating level at Devil Canyon
is Elevation 1455, which corresponds to the tailwater level
selected at the Watana site. Although the narrow configur-
ation of the Devil Canyon site and the relatively low costs
involved in increasing the dam height suggest that it might
be economic to do so, it is clear that the upper economic
limit of reservoir level at Devil Canyon is the Watana
tailrace level.
Selection of Installed Capacity
Devil Canyon will be operated primarily as a base loaded
plant for the following reasons:
-Daily peaking is more effectively performed at Watana
than at Devil Canyon; and
-Excessive fluctuations in discharge have an undesirable
impact on downstream fisheries.
Given this mode of operation, the required installed capac-
; ty at Dev i 1 Canyon has been determined as the maximum
capacity needed to utilize the available energy from the
hydrological flows of record, as modified by the reservoir
operation rule curves.
The required total capacity at Devil Canyon in a wet year,
based on the December 1981 Battelle medium load forecast,
varies between 370 MW and 507 MW over the period 2002
through 2010, excluding standby and spinning reserve capac-
ity. The total installed capacity at Devil Canyon has been
established as 600 I~W for design purposes. This will pro-
vide some margin for forced outage and possible accelerated
growth in demand.
The major factors governing the selection of the unit size
at Devil Canyon are the rate of growth of system demand,
the minimum station output, and the requirement of standby
capacity under forced outage conditions. The power facili-
ties at Devil Canyon have been developed using four units
at 150 MW each. This arrangement will provide for effic-
ient station operation during low load periods as well as
during peak December loads. It has been assumed that all
units will be commissioned by 2002.
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(iii) Selection of Spillway Design Floods
A flood frequency of 1:10,000 years equivalent to 165,000
cfs was selected for the spillway design on the same basis
as Watana. An emergency spillway with an erodible fuse
plug will also be provided to safely discharge the PMF of
366,000 cfs. The inflow flood peaks at Devil Canyon will
be less than pre-project flood peaks because of routing
through the Watana reservoir.
The avoidance of nitrogen supersaturation in downstream
flows also will apply to Devil Canyon. Thus, the discharge
of water possibly supersaturated with nitrogen from Devil
Canyon will be limited to a recurrence period of not less
than 1:50 years by the use of fixed-cone valves similar to
Watana.
(d) Devil Canyon Scheme Development
Study of alternative scheme configurations at Devil Canyon was
based on investigations of the dam, diversion, spillway, and power
facility structures.
(i) Main Dam Alternatives
The location of the Devil Canyon damsite was examined dur-
ing previous studies by the USBR and COE. These studies
focused on the narrow entrance to the canyon and led to the
recommendation of a concrete arch dam. Notwithstanding
this initial appraisal, a comparative analysis was under-
taken as part of this feasibility study to evaluate the
relative merits of the following types of structures at the
same location:
-Concrete gravity dam;
-Thick concrete arch;
-Thin concrete arch; and
-Fill embankment.
Preliminary comparisons of gravity, arch and rockfill dam
alternatives indicated a trend in favor of the concrete
arch dam alternatives. The assessment showed that a con-
crete gravity dam in the narrow gorge would be more expen-
sive and tend to behave similarly to an arch dam, but would
not have the flexibility of such a structure under severe
seismic shaking conditions. Consideration of a central
core rockfill dam at Devil Canyon indicated a trend in
favor of a conservative arch dam cost estimate, based on a
dam cross-section significantly thicker than the finally
selected design.
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Two types of arch dam were considered c3t the site~ a thin
arch and a thicker, gravity arch. Suitable sand c3nd gravel
for concrete aggregates are available in sufficient quanti-"
ties close to the damsite. There are no geological or geo-
technical concerns in regard to bedrock that would preclude
either dam type from consideration. However, the studies
showed that although the thin arch arrangement did not ap-
pear to have a distinct technical advantage compared to a
thick arch dam, it would be less expensive because of the
smaller volume of concrete needed, The thin arch alterna-
tive was therefore selected for detailed study.
(ii) Diversion Scheme Alternatives
The selection process for establishing the final general
arrangement for diversion included examination of tunnel
locations on both banks of the river. Rock conditions for
tunne 1 ing did not favor one bank over the other. Access
and ease of construction strongly favored the left bank.
The main dam could be subjected to overtopping during con-
struction without causing serious damage, and the existence
of the Watana facility upstream will offer considera,ble
assistance in flow regulation in case of an emergency.
These considerations led to the selection of a 25-year de~
sign flood of 37,800 cfs for this site. As at Watana, the
considerable depth of riverbed alluvium at both cofferdam
sites indicates that embankment type cofferdqrn structures
would be the only technically and economically feasible
c1lternat ive at Devil Canyon. Consideration of a number of
alternative tunnel arrangements tuliminated in selection of
a single 30-foot diameter pressure tunnel arrangement, An
upstream cofferdam 60 feet high, with a crest elevation of
945, was carried forward as part of the selected general
arrangement.
(iii) Spillway Alternatives
The project spi 11 ways have been designed to safely pass a
1:10,000-year flood discharge of 165,000 cfs and a PMF of
365,000 cfs.
A number of alternatives were considered singly and in com-
bination for Devil Canyon spillway facilities and loca-
tions. These included gated orifices in the main dam dis-
charging into a plunge pool, right and left bank, chute or
tunnel spillways with either a flip bucket or st i 11 ing
basin for energy dissipation, and open channel spillways.
The se 1 ected arrangement wi 11 comprise a gated spillway
control structure and chute in the left bank with energy
dissipation by a flip bucket which directs the spillway
2-31
( i v)
discharge in a free-fall jet into a plunge pool in the
river. Restrictions with respect to nitrogen supersatura-
tion have been applied in selecting acceptable spillway
discharge structures. The main spillway is designed to
pass 135,000 cfs, the remaining 30,000 cfs being discharged
through seven fixed-cone valves in the dam. The selected
emergency spillway is an open channel with erodible fuse
plug in the left abutment of the dam.
Power Facilities Alternatives
A surface powerhouse at Devil Canyon would be located
either at the downstream toe of the dam or along the side
of the canyon wall. An underground arrangement was favored
however because insufficient space is available in the
steep-sided canyon for a surface powerhouse at the base of
the dam. Provision of an extensive intake at the crest of
the arch dam would also be detrimental to stress conditions
in the arch dam particularly under earthquake loading.
Underground powerhouse and related facilities have there-
fore been located on the right bank where topographic cond-
itions are generally more favorable, ana rock quality is
superior at depth.
For the design head and specific speed, four Francis tur-
bine units have been selected. These are rated to deliver
150 MW each at full gate opening and minimum reservoir
level in December, the peak aemand month. Six single-phase
transformers will be installed underground to serve the 4
units, similar to Watana. For flexibility of operation, 4
individual penstocks are provided to each of the 4 units.
A single chamber and single tailrace tunnel with a length
of 6,800 feet to develop 30 feet of additional head down-
stream from the dam has been incorporated in the design.
Detailed studies comparing construction cost to the value
of energy lost or gained were carried out to determine the
optimum diameter of the water passages.
(v) Environmental Constraints
In addition to potential nitrogen-saturation problems
caused by spillway operation, the major impacts of the
Devil Canyon power facilities development are:
-Changes in the temperature regime of the river; and
-Fluctuations in downstream river flows and levels.
Temperature modeling has indicated little benefit to be
gained by constructing a multiple level intake design at
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( vi)
Devil Canyon. The intake therefore incorporates a single
level draw-off about 75 feet below maximum reservoir oper-
ating leveL The Devil Canyon station will normally be
operatecj as a base-loaded plant throughout the year, to
satisfy the req1.1irement of no significant daily variation
in power flow-
Selection of Devil Canyon General Arrangement
PrelirninilrY fllternative arrangements of the Devil Canyon
project were developeq and a preferred arrangement sel-
ected. Topographic conqitions at this site limited the
development of re!lsonarly feasible layo1~ts, and initially,
four sch~mes were dE:~~lopeq and evaluated. During the
final review~ the selected lc1yout was refined pased on
ter:hnical~ operationi'Il, and environmental considerations
iqentified during the preliminc1ry review-
2.8 -Watana Development
The project site is located in a broc1d U-shaped valley at river mile
184, approximately 2-5 miles upstream of the confluence of Tsusena
Creek with the Susitna River. The river at the site is relatively
wide, although turbulent.
(a) Geologic Conditions
The site is generally characterized by up to 80 feet of overbur-
den, consisting of talus, glacial silts, sands, gravels, and boul-
ders. The riverbed consists of c1bout 80 feet of alluvial sand,
silt, coarse grq.vels, and boulders. Permafrost conoitions exist
generq.lly on the north-facing slopes (left bank) of the damsite
area and in sporadic areas of the north abutment.
The damsite is primarily underlain by an intrusive dioritic body
which varies in composition from granodiorite to quartz diorite to
diorite. The rock is hard, competent, and fresh except within
shear zones, and has been intruded by mafic and felsic dikes which
are generally only il few feet thick-The rock immediately down-
stream from the damsite is an andesite prophyry, containing quartz
diorite inclusions.
The topography of the Watana reservoir and adjacent slopes is
characterized by a narrow V-shaped stream-cut valley superimposed
on a broad U-shaped glacial valley. The lower portions of the
Watana reservoir are predominantly covered by a veneer of glacial
till with scattered outwash deposits. The river valleys contain
significant amounts of alluvial deposits and reworked outwash.
The mai'n structural feature of the Watana reservoir is the Tal-
keetna Thrust, an inactive fault which trends northeast-
southwest, crossing the Susitna River approximately eight miles
upstream from the damsite.
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(b) Geotechnical Design Considerations
Detailed investigations have been undertaken to evaluate the geo-
technical aspects of design of the dam and other major structures
at the Wa tan a s it e.
The riverbed alluvium ranges up to approximately 100 feet in
depth. The character of this material has not yet been well
defined and its stability during a strong earthquake event is
questionable. It will therefore be removed under the dam. The
strength of the rock found at ion is adequate to support the embank-
ment and associ a ted reservoir loads. Seepage under the dam will
be controlled by the provision of a grout curtain cutoff combined
with a downstream drainage system.
(i) Underground Structures
The rock conditions at the Watana site are suitable for the
construction of tunnels and underground caverns. The ori-
entation and location of rock discontinuities have been a
major factor in selection of the alignments of the tunnels
and major caverns to achieve maximum stability ana minimum
support requirement. Permafrost conditions will not have
any major adverse impact except where thawing may be re-
quired for grouting. Conventional rock bolt support is
generally considered adequate in most areas with spans less
than 40 feet. For larger spans and in areas of poor qual-
ity rock, the support requirements have been determined on
a case-by-case basis. Tunnel excavation can be performed
using conventional drill and blast techniques or high pro-
duction mechanical excavating equipment.
(ii) Relict Channel
A deep bedrock depression exists on the north bank of the
river extending from about 2,500 feet west of Deadman Creek
northwest toward Tsusena Creek. The depth to bedrock is as
much as 400 feet below the surface and the reservoir level.
The overburden consists of several sequences of glacial
deposits, lake sediments, and alluvium varying in thickness
and character, and containing some permafrost. With the
proposed range of reservoir levels, these overburden depos-
its will become saturated, which may lead to potential de-
sign problems.
Additional investigations will be necessary to properly
characterize the subsurface conditions in the area prior to
construction.
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( i ii) Seismic Considerations
For earthquake engineering and design considerations, the
project structures have been classified as either critical
or non-critical structures. Critical structures wi 11 be
designed to safely withstand the effect of the selected
"Safety Evaluation Earthquake" (SEE) for the site. No sig-
nificant damage to these structures will be accepted under
these conditions. The design of non-critical structures
for earthquake conditions is undertaken on the basis. of
conventional Uniform Building Code recommendations.
Two sources wi 11 be used for determination of the most
severe SEE condition for design of structures at Watana, a
Benioff Zone maximum earthquake of magnitude 8.5 at a dis-
tance of 40 miles from the site, and a Terrain maximum
earthquake of magnitude 6.25 at a distance of less than 6
miles from the site.
Although the "Terrain" earthquake would result in more
severe ground motions, the duration of these motions is
relatively short and the likelihood of occurrence of such
an event is extremely small. The design of the Watana dam
has therefore been based on the projected time history for
the Benioff event.
(c) General Arrangement
General arrangement drawings for Watana are presented in Volume 3
of this report.
The Watana dam will form a reservoir a~proximately 48 miles long,
with a normal maximum operating elevation of 2185. The dam will
be a 62 million cubic yard earthfill structure with a central im-
pervious core. The crest elevation of the dam will be 2210, with
a maximum height of 885 feet and a crest length of 4,100 feet.
During construction, the river will be diverted around the main
construction area by means of two 38-foot-diameter, concrete-lined
diversion tunnels on the right bank of the river.
A power intake and approach channel will be located on the right
bank, leading to a multilevel gated intake structure capable of
operation over a 140-foot drawdown range. From the intake struc-
ture, six 17-foot-diameter penstocks will lead to an underground
powerhouse complex housing six 170 MW Francis turbine-generator
units. Access to the powerhouse complex will be by means of an
unlined access tunnel. Turbine discharge will be conducted
through six draft tube tunne 1 s to a surge chamber downstream from
the powerhouse, then by means of two 30-foot-d i ameter concrete-
1 ined tailrace tunnels to the river downstream. A separate trans-
former gallery upstream from the powerhouse cavern will house nine
2-35
single-phase 15/345 kV transformers. The transformers will be
connected by 345 kV single-phase, oil-filled cable through two
cab 1 e shafts to the switchyard at the surface. A tunne 1 out 1 et
facility located on the right bank will discharge all flows re-
sulting from floods having a return frequency of 1:50 years or
less. This structure will be equipped with six fixed-cone valves
at the downstream end to minimize undesirable nitrogen supersatur-
ation in the river downstream from the dam during spillway opera-
tions. Flows resulting from floods with a frequency greater than
1:50 years but less than 1:10,000 years will be discharged by a
main chute spillway also on the right bank. The spillway control
structure at the upstream end will be controlled by three fixed
wheel gates leading to a concrete-1 ined chute and flip bucket at
the downstream end. An emergency spillway on the right bank will
provide sufficient additional capacity to permit discharge of the
PMF without overtopping the dam. An emergency release facility
will allow lowering of the reservoir over a period of time to
permit emergency inspection or repair.
(d) Site Access
Extensive studies were undertaken of a number of alternative ac-
cess corridors to the sites. The selected route is considered to
be the best compromise of the technical, economic, environmental,
social and schedule factors involved. This route will be via a
paved road starting near Hurricane on the Parks Highway from
whence the route will proceed southeast to the vicinity of Gold
Creek. A bridge will be constructed south of Gold Creek from
which the road will be routed south of the Sus itna River to a
second low-level bridge upstream of the Devil Canyon site. From
this point the road wi 11 be north of the river to Watana. In
addition to the main access, several additional roads will be re-
quired to access the various site facilities and structures. The
construction roads will be 40-foot wide gravel surfaced roads with
small radius curves and grades 1 imited to 10 percent. Major cut
and fill work will be avoided. The completed main dam crest will
provide permanent access across the Susitna River, and an access
tunnel will be provided to the underground powerhouse.
A permanent 6,000 foot airstrip will be constructed approximately
2.5 miles north of the main construction camp. A temporary 2,500
foot airstrip will also be constructed to support the early phases
of mobilization and construction.
(e) Site Facilities
The construct ion of the Watana deve 1 opment will require various
support facilities throughout the construction period. Following
construction, the operation of Watana will require other facili-
ties to support the permanent operation and maintenance of the
project. The site facilities, including housing, recreation,
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water supply, and sanitary facilities will be located on the north
bank of the river about 2.5 miles northeast of the dam. It will
be a combination camp and village which will accommodate up to
4~000 people during construction of the project. After construc-
tion is complete, it is planned to dismantle and demobilize the
construction camp facility and to reclaim the area. Required per-
manent facilities w-ill support a community of approximately 130
staff members and their families. Other permanent facility items
will include a maintenance building for use during subsequent
operation of the power plant.
During the first two years of construct ion, power supply will be
provided by diesel generators. A single 345 kV transmission line
will be constructed to service the site from 19137 onward. This
line will be operated at 138 kV until commissioning and subse-
quently will be part of the permanent system supplying power to
the interie at 345 kV.
Main Dam
The main dam at Watana is 885 feet high and will be among the
highest in the world. The Watana site is located in a seismically
active area. The major design features of 24 embankment dams be-
tween 350 and 795 feet in height constructed in seismic areas com-
pare favorably with the Watana design. These comparisons indicate
that the proposed Watana design is generally conservative with re-
spect to precedent design. However, some additional special fea-
tures have also been incorporated in the Watana section to provide
additional safeguards against seismic loading.
The embankment will consist of a central compacted core protected
by fine and coarse filters on both sides. The downstream outer
shell will consist of rock fill and alluvium gravel; and the up-
stream outer shell of clean alluvium gravel.
The proposed impervious material core is a combination of glacial
outwash and tills with a wide grain size distribution. It is non-
plastic and would tend to crack rather than deform under tensile
stress. A central vertical core was chosen for the embankment
rather then a sloping core based on a review of precedent design
and the nature of the proposed impervious material.
Because of the apparent low plasticity of the impervious core ma-
terial and the requirement for an earthquake resistant design, a
number of special design features will be incorporated into the
main dam cross-sect ion. These include measures to· withstand the
effects of severe seismic shaking, such as widening of the core-
foundation contact near the ends of the embankment to ensure seep-
age control, and careful attention in design of filters which will
be self-healing in case of transverse cracks in the core. Com-
pacted processed clean river alluvium gravel of high permeability
2-37
wi 11 be used to construct the upstream outershe 11 to rn1 n1 m1 ze
settlement displacement and to ensure rapid dissipation of any
pore pressure buildup which may occur.
(g) Stability Analysis
Static and dynamic stability analyses have been performed to con-
firm the stabi 1 i ty of the upstream and downstream slopes of the
Watana dam. The analyses indicate stable slopes under all condi-
tions for a 2.4H:1V upstream slope and 2H:1V vertical downstream
slope.
The static analyses were used to determine the initial stresses in
the dam during normal operating conditions. The dynamic analyses
were made using a finite element model to incorporate strain
dependent shear modulus and damping parameters. The design earth-
quake for the dynamic analyses was developed for a Benioff Zone
event, magnitude 8.5 at a distance of 40 miles from the site.
The following conditions were analyzed under static conditions:
Condition
Construction
Normal Operating
Rapid Dr awdown
Required
Minimum Factor
of Safety
1.3
1.5
1.0
Calculated Factor
of Safety
U/S Slope D/S Slope
2.2 -2.2
2.0
1.8 -2.0
1.7
1.7
1.7
The calculated factors of safety indicated no general slope sta-
bility problems under static loading.
In the dynamic analysis, estimated values were used for material
properties such as shear modulus, based on published data. The
analysis was based on a time history developed for the design
earthquake, with a maximum acceleration of 0.55g; and a duration
of strong motion of 45 seconds. The results of this analysis are
dependent on the accuracy of the assumed material properties.
However, they do indicate with some degree of confidence that the
dam will safely withstand this seismic event, with minimal damage
such as typical minor surface raveling.
(h) Relict Channel Treatment
The buried channel is located between the Susitna River gorge im-
mediately upstream from the proposed damsite and Tsusena Creek, a
distance of about 1.5 miles. The surface elevation of the lowest
point of the saddle is approximately 2005 feet. Along the channel
thalweg, the highest bedrock surface is some 450 feet below reser-
voir and the highest gradient along the buried channel from the
edge of pool to Tsusena Creek is approximately 9 percent. Zones
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of permafrost have also been identified thro~ghout the channel
area. Potential problems associated with the buried channel are
leakage, both surface and subsUrface flows; piping at downstream
outlets to Tsusena Creek; the impact of permafrost and the long-
term effects as heat from the reservoir thaws the ground through
the channel area; and instabi 1 ity of soil slopes on saturation,
thawing, or seismic loading leading to a breach of the rim of the
reservoir. The stab i 1 i ty of the section of the buried channe 1
forming the rim of the Watana reservoir is essential for the feas-
ibility of the Watana development. Appropriate measures have
therefore been provided in the design.
To eliminate these potential problems, the maximum operating level
of the reservoir has been set at 2185 feet leaving a width of at
least 1500 feet of 11 dry11 ground at the saddle above this eleva-
tion. A low freeboard dike with a crest elevation of 2010 will
also provide protection against extreme reservoir levels under PMF
flood conditions. The potential for piping and erosion .in the
area of discharge into the Tsusena Creek will be controlled by
placement of a filter blanket over the zones of emergence. Field
investigation will be carried out to define critical areas, and
only such areas will be treated since tt may take many years for
equilibrium with respect to the permafrost regime to become estab-·
lished in the buried channel area.
To guarantee the integrity of the reservoir rim through the chan-
nel area it is required that either:
-There is no potential for a liquefaction slide into the reser-
voir which could cut back and breach the rim; or
If there is such potential, there ris a sufficient volume of
stable material at the critical section that even if the up-
stream materials were to slide into the reservoir, the failure
zone could not cut back to the reservoir rim.
A better knowledge of the in situ materials in the relict channel
will be possible with additional exploration. The potential for
1 i quef action can then be better defined. With the 1 i mi ted i nfor-
mation currently available, in the worst case the most positive
solution would be the replacement of the zones which may be sub-
ject to liquefacation with material that would not liquefy. This
would involve, in effect, the rearrangement of the in-place mate-
rials to create an underground dam section founded on the dense
till layer beneath the critical alluvium. The cost of such work
is estimated to be about $100 million. The need of such expendi-
ture is considered to be most unlikely and is deemed to be covered
by the overall project cost contingency allowance.
2-39
( i) Reservoir
The Watana reservoir, at normal operating level of 2185 feet, will
be approximately 48 miles long with a maximum width in the order
of five miles. The minimum reservoir level will be 2045 feet dur-
ing normal operation, resulting in a maximum drawdown of 140 feet.
The reservoir will have a total capacity of 9,520,000 acre-feet of
which 4,210,000 acre-feet will be live storage.
Prior to reservoir filling, the area below Elevation 2190, five
feet above maximum operating level, will be cleared of all trees
and brush. In the Watana reservoir area, an estimated 18,0lJO,OOO
cubic feet of wood exists, of which approximately 87 percent are
soft woods. Present market demand for the timber at Susitna is
low; however, the worldwide demand for wood fluctuates consider-
ably. It is anticipated that use of the harvested material would
be 1 imited to sale either as wood-waste products or as fuel.
Slash material including brush and small trees, which wi 11 be un-
suitable for either of the above uses, will be either burned in a
carefully controlled manner consistent with applicable laws and
regulations, or hauled to a disposal site in and adjacent to the
reservoir. Material placed in disposal areas will be buried with
an earthfill cover sufficient to prevent erosion and subsequent
exposure.
2.9 -Devil Canyon Development
The Devil Canyon site is located at river mile 152 of the Susitna
River, approximately 32 miles downstream from the Watana site, in a
V-shaped sect ion near the entrance to the canyon which is about two
miles long. The river at this site is relatively narrow and extremely
turbulent. The canyon is characterized by steep walls, particularly on
the left bank which features overhanging cliffs and detached blocks of
rock.
(a) Geologic Conditions
The valley walls are generally covered by a thin veneer of over-
burden consisting primarily of talus at the base. The flatter up-
land areas are covered by 5 to 35 feet of overburden of glacial
or1g1n. A topographic depression along the elongated lakes on the
south bank has an overburden covering in excess of 85 feet of
glacial materials. The overburden on the alluvial fan or point
bar deposit at the Cheechako Creek confluence thickens from 100
feet to more than 300 feet over a distance of less than 400 feet.
The river channe 1 a 11 uv i um appears to be composed of cobbles,
boulders, and detached blocks of rock and is inferred to be up to
30 feet thick. No permafrost was found in either the bedrock or
surficial material at or around the damsite.
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The bedrock at the Devil Canyon site is a low-grade metamorphosed
sedimentary rock consisting predominantly of argillite with inter-
beds of graywacke. The argillite is a fresh, very thinly bedded,
very fine grained argillaceous rock. The graywacke is generally a
fresh, mainly fine-grained sandstone with an argillaceous matrix,
interbedded with the argillite in beds generally less than six
inches thick. The area has also been intruded by numerous felsic
and mafic dikes ranging from 1 inch to 60 feet wide (averaging 20
feet). When closely fractured they are easily eroded and tend to
form steep talus-filled gullies, some of which exhibit shearing
with the host rock.
The Devil Canyon reservoi.r will be confined to a narrow canyon
where the topography is controtlled by bedrock. The ov~rburden is
thin to nonexistent, except in the upper reaches of the reservoir
where alluvial deposits cover the valley floor. A large intrusive
plutonic body composed predominantly of biotite granodiorite with
local areas of quartz diorite and diorite underlies most of the
reservoir and adjacent slopes. Argillite and graywacke are also
present. The rock has been isoclinically folded into steeply
dipping structures str'i king generally northeast-southwest. The
argillite has been intruded by massive granodiorite, and as a
result, large isolated roof pendants of the argillite and gray-
wacke are found locally throughout the entire reservoir and
surrounding areas.
(b) Geotechnical Design Considerations
The geotechnical investigations to date have been primarily dir-
ected toward the important geological features which may have sig-
nificant impact on the feasibility of the project. The geologic
and topographic conditions are favorable for an arch dam at the
Devil Canyon site. The rock is principally hard, competent, and
fresh with weathering limited to joints and shear zones. Intru-
sive mafic and felsic dikes, where present, are hard, the contact
with the parent rock is tight, and they have no important adverse
effect on the stability of the abutments .. The stresses imposed by
the arch dam will be well within acceptable limits for the rock.
On the right abutment, the arch ~am thrust block will be required
to transfer the loads to competent rock. This thrust block will
form an abutment to the saddle dam.
(i) Underground Structures
The rock conditions at the site are generally suitable for
the construction of tunnels and underground caverns. For
the most part, conventional rock bolt support has been as~
sumed to be adequate for openings 1 ess than 40 feet in
span. For 1 arger spans, in areas of poor quality rock and
where rock discontinuities are known to be adversely ori-
ented, support requirements have been determined on a
case-by-case basis.
2-41
(i i) Saddle Dam Foundation
The saddle dam on the south bank will be constructed across
a buried channel where the thickness of overburden is up to
80 feet. The bedrock below (argillite and graywacke) the
area is competent. The prominent shear zone or fault which
was found in the saddle dam foundation, together with
various shear and fracture zones, will require treatment by
consolidation and curtain grouting under the core.
(iii) Seismic Considerations
As for Watana, critical structures at Devil Canyon, such as
the arch dam, will be designed to safely withstand the ef-
fect of the 11 Safety Evaluation Earthquake,. {SEE) for the
site. No significant damage to these structures will be
accepted under these conditions.
As at Watana, two earthquake sources have been considered
for determination of the SEE for critical structures at
Devil Canyon. For the arch dam and other critical concrete
structures, a Terrain maximum earthquake of magnitude 6.25
at a distance of less than 6 miles from the site will be
used as the basis for design. For the saddle dam, the
projected time history for a Benioff Zone maximum earth-
quake of magnitude 8.5 at a distance of 57 miles from the
site will be used.
(c) General Arrangement
Devil Canyon will form a reservoir approximately 26 miles long
with a total volume of 1,092,000 acre-feet at a normal maximum
operating elevation of 1455. The operating level of the Devil
Canyon reservoir is controlled by the tailwater level of the up-
stream Watana development. During operation, the reservoir will
be capable of being drawn down to a minimum elevation of 1405.
The dam will be a thin arch concrete structure with a crest eleva-
tion of 1465 and maximum height of 645 feet. An earth-and rock-
fill saddle dam will provide closure to the left bank. The saddle
dam will be a central core type generally similar in cross-section
to the Watana dam. This dam will have a maximum height above
foundation level of approximately 260 feet.
During construction, the reservoir will be diverted around the
main construction area by means of a single concrete-lined diver-
sion tunnel 30 feet in diameter on the left bank of the river. A
power intake located at the right bank will comprise an approach
channel in rock leading to a reinforced concrete gate structure.
From the intake structure four penstocks, consisting of concrete-
lined tunnels each 20 feet in diameter, will lead to an under-
ground powerhouse camp lex housing four Francis turbine-generator
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units each with a rated capacity of 150 MW. Access to the power-
house complex will be by means of an unlined access tunnel ap-
proximately 3,200 feet long, as well as a vertical access shaft
about 950 feet deep. Turbine discharge will be conducted to the
river by means of a single 39-foot-diameter tailrace tunnel lead-
; ng from a surge chamber downstream from the powerhouse cavern.
Compensation flow pumps at the power plant will ensure suitable
flow in the river between the dam and tailrace tunnel outlet por-
tal. A separate transformer gallery just upstream from the power-
house cavern will house six single-phase 15/345 kV transformers.
The transformers will be connected by 345-kV, single-phase, oil-
filled cable through a cable shaft to the switchyard at the sur-
f ace.
Seven individual outlet conduits will be located in the lower part
of the main dam to discharge all floods with a frequency of 1:50
years or less. Each outlet conduit will have a fixed-cone valve
similar to those provided at Watana to minimize undesirable nitro-
gen supersaturation in the flows downstream. Flows resulting from
floods with a frequency greater than 1:50 years but less than
1:10,000 years will be discharged by a chute spillway on the right
bank, also similar in design to that provided for Watana. An
emergency spillway on the left bank will provide sufficient addi-
tional capacity to permit discharge of the PMF without overtopping
the dam. An emergency-release, low-level outlet facility will
allow lowering of the dam to permit emergency inspection or re-
pair.
Site Access
At Devil Canyon the main access road to 1the Watana site will enter
the site from the south. The existing low., level bridge upstream
from the dam will be used to cross the Susitna River during con-
struction. After construction of the main dam is completed, the
crest of the main dam will provide access across the Susitna
River. The permanent airstrip located at the Watana site, ap-
proximately 30 miles west of the Devil Canyon site, will be used
for the Uevil Canyon development.
(e) Site Facilities
The construction of the Devil Canyon development will require var-
ious facilities to support the construction activities throughout
the entire construction period. Following construction, the plan-
ned operation and maintenance of the development will be centered
at the Watana development; therefore, minimum facilities at the
site will be required to maintain the power facility.
A camp and construction village with water supply and sanitary
facilities wjll be constructed and maintained approximately 2.5
miles west of the project site. The camp/village will provide
2-43
housing and recreation facilities for up to 1,900 people during
construction. Other site facilities include contractor•s work
areas, site power, services, and communications. Items such as
power and communications and hospital services will be required
for construction operations independent of camp operations. It is
planned to dismantle and demobilize the facility upon completion
of the project, after which the area will be reclaimed.
S'ince the Watana development will be in service during the con-
struction period, electric power will be available. It is there-
fore planned to meet all heating requirements with electric heat.
(f) Arch Dam
The arch dam will be located at the upstream end of the canyon at
its narrowest point. The height of the dam will be 645 feet, well
within the range of heights of similar dams constructed elsewhere.
The dam is designed to withstand dynamic loadings from seismic
shaking. A number of other dams constructed throughout the world
in seismically active areas have withstood earthquake loadings as
high as 0.6g to 0.8g. Green Lake Dam is presently being construc-
ted to a height of 210 feet in Sitka, Alaska.
The rock forming the right abutment rises several hundred feet
above the dam crest but on the left side the rock surface rises
only to Elevation 1400. It will be necessary to construct a mass
concrete thrust block at this point to artificially form the bear-
ing surface of the dam.
The dam will be founded on sound bedrock located 20 to 40 feet be-
low the bedrock surface. The foundation will be excavated and
trimmed beneath the dam so that no abrupt irregularities will oc-
cur at the foundations which could cause stress concentrations
within the concrete.
(g) Design Analysis
The crown section at the center of the river wi 11 be of a daub 1 e
curved cupola shape inclined downstream. The static load from the
reservoir will be taken primarily in the arches; the three-
dimensional stress action of the structure will tend to induce
tension in the downstream face of the cantilever. This will be
offset by the gravity forces of the overhangtng section, which al-
so wi 11 counteract any loadings produced by downstream ground
motion during an earthquake.
A two-center configuration wi 11 be adopted for the arches to
counteract the slight assymetry of the valley and give a more uni-
form stress distribution across the dam. Stress analyses show
that the structure wi 11 safely withstand the Terrain SEE, magni-
tude 6.25. For conservative structural design purposes, a mean
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spectral acceleration of 0.55g and 10 percent damping ratio has
been adopted at the site.
Construction of the dam will be completed over a five-year period.
Concrete will be placed by means of three high lines strung above
the dam between the abutments. Construction will take place
throughout the year with cooling coils built into the concrete to
dissipate the heat of hydration and special heating and insulating
precautions taken in the winter to prevent excessive cooling of
concrete surfaces. Concrete aggregates will be obtained from the
alluvial deposits in the terraces upstream from the dam.
(h) Saddle Dam
The design philosophy for the saddle c;lam at lJevil Canyon is sim-
ilar to that for the main dam at Watana. The most significant
difference is the exclusive use of rockfill in the shells instead
of river gravels used for the much higher Watana dam. The central
vertical impervious core will be protected by fine and coarse fil-
ters on both upstream and downstream slopes and supported by rock-
fill shells. The wide filter zones will provide sufficient mate-
rial for self-healing of any cracks which might occur in the core
because of settlement or as the result of seismic disturbance.
The saturated sections of both shells will be constructed of com-
pacted clean rockfill, processed to remove fine material in order
to minimize pore pressure generation and ensure rapid dissipation
during and after a seismic event. Protection on the upstream
slope will consist of a 10-foot layer of riprap.
No source of material suitable for the core of the saddle dam has
been identified closer than the borrow areas at Watana (Sites D
and H). Since access roads will be established to that area, the
SiteD source will be used for the Devil Canyon core. Investiga-
tions to date indicate that suitable material can be obtained from
areas above the Watana reservoir level. The filter material will
be obtained from the river deposits (Site G) immediately upstream
from the main arch dam at Devil Canyon. This area will also be
exploited for concrete aggregates. Rockfill for the saddle dam
shells will be obtained primarily from the excavations for the
spillway, tunnels, and powerhouse complex.
As at Watana, special precautions have been taken to ensure sta-
bility under earthquake loading by the use of processed free-
draining rockfill in the saturated zones of the dam, the incorpor-
ation of very wide filter zones, and the removal of all unconsoli-
dated natural material from beneath the dam. Static and dynamic
stability analyses of the upstream slopes of the Watana dam have
confirmed stable slopes under all conditions for 2.4H:1V upstream
slope and a 2H:1V downstream slope. The Devil Canyon saddle dam
is therefore also considered to be stable under such conditions.
2-45
(i) Reservoir
The Devil Canyon reservoir, at a normal operating level of 14!:>5
feet, will be approximately 26 miles long with a maximum width in
the order of 1/2-mile. The total surface area at normal operating
level is 7,800 acres.
Present market demand for the timber at Susitna is low, however,
the worldwide demand for wood fluctuates considerably. It is an-
ticipated that use of the harvested material would be limited to
sale either as wood-waste products or as fue 1. Slash material
including brush and small trees, which will be suitable for either
of the above uses, will be either burned in a carefully controlled
manner consistent with applicable laws and regulations, or hauled
to a disposal site in and adjacent to the reservoir.
2.10 -Transmission Facilities
The project transmission facilities are required to provide a power de-
livery system from the Susitna River Basin generating plants to the
major load centers in Anchorage and Fairbanks. This system will be
comprised of transmission lines, substations, a dispatch center, and
means of communications. Transmission planning criteria were developed
and electric system studies undertaken to ensure the design of a reli-
able and economic electrical power system, with components rated to
allow a smooth transition through early project stages to the ultimate
developed potential. These criteria were essentially based on delivery
of total power output of Susitna to one or two substations at Anchorage
and one at Fairbanks.
Studies of alternative transmission voltages, hardware, and substation
configurations resulted in selection of the following economic optimum
arrangement for the Susitna development:
Number of Number and S i ze
Line Section ~ Circuits vo 1 tase of Conductors
1 (kcmi l) (kV
Watana to Devil Canyon 27 2 345 2 by 954
Devil Canyon to Fairbanks 189 2 345 2 by 795
Devil Canyon to Will ow 90 3 345 2 by 954
Willow to Knik Arm 38 3 345 2 by 954
Knik Arm Crossing 4 3 345 Submarine cable
Knik Arm to University
Substation 18 2 345 2 by 1351
Substations for this system will be located at each site and also at
Esker (Fairbanks), Willow, Knik Arm (east shore), and University
(Anchorage). The Esker substation will provide a connection of Susitna
power to the GVEA system and the University substation to the CEA and
AMLP systems. The segment of the system between Willow and Healy will
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incorporate the intertie which is currently being planned as a single
line to be operated initially at 138 kV and subsequently upgraded to
345 kV .
Extensive studies were undertaken to select appropriate carr idors and
routes for the transmission lines. A number of alternative 3 to 5 mile
wide corridors were investigated, and the selected corridor provided
the optimum tradeoff of the technical, economic, and environmental fac-
tors involved. These studies were undertaken in parallel and coordin-
ated with similar studies for the intertie. The selected corridors
were subsequently subjected to a process of refinement and more de-
tailed evaluation to identify the preferred 1/2-mile wide route in
which to locate the transmission right-of-way. The required right-of-
way will vary from 400 feet for 3 lines to 700 feet for 5 lines. This
process was based on similar technical, economic, and environmental
criteria to the corridor selection studies during the route selection
phase. Particular emphasis was placed on satisfying regulatory and
permit requirements, aesthetics, and avoidance of developed areas.
A hinged-guyed, two-legged steel X-tower was selected for all proposed
transmission l·ines, including the intertie. Design features of these
towers include hinged connect ions between the leg membe~s and founda-
tions and longitudinal guy systems which provide flexibility and sta-
bility. These are important considerations in the unique foundation
and climate conditions in this area of Alaska. The selected design is
considered to be a sound compromise of reliability, durability, econ-
omy, and aesthetics.
2.11 -Construction Cost Estimates and Schedules
Estimates of construction costs for the Watana and Devil Canyon devel-
opments have been prepared on a uniform Jan~ary 1982 cost basis. These
estimates are based on detailed construction schedules and quantity
takeoffs for the designs developed for the entire project during the
course of the study. Allowances have been made for unique construction
conditions in Alaska where the remoteness of the project area and the
severity of the climate will have significant effects.
(a) Estimate of Cost
The estimated costs of the project-in January 1982 dollars, are as
follows:
$ X 106
Categor~ Watana Devil C an~on Total
Production Plant 1,986 835 2,821
Transmission Plant 391 91 482
Ge n er a l P l ant 5 5 10
Site Facilities 378 188 566
Subtotal 2,760 1,119 3,879
Contingency (17.5%) 482 196 678
Total Construction 3,242 1,315 4,557
Engineering & Administration (12.5%) 405 165 570
Project Total 3,647 1,480 5,127
2-47
Of these costs, $112,775,000 at Watana and $36,303,000 at Devil
Canyon are attributable to mitigation measures such as outlet
facilities, restoration, multilevel intakes, etc., incorporated in
the projects.
At current high levels of interest rates in the financial market-
place, allowance for funds used during construction (AFDC) will
amount to a significant element of financing cost for the lengthy
periods required for construction of the Watana and Devil Canyon
projects. However, in economic evaluations of the Susitna proj-
ect, the low real rates of interest assumed would have a much re-
duced impact on assumed project development costs. Furthermore,
direct state involvement i~ financing of.the Susitna project will
also have a significant impact on the amount, if any, of AFDC.
For purposes of the current feasibility study, therefore, the con-
ventional practice of calculating AFDC as a separate line item for
inclusion as part of project construction cost, has not been fol-
1 owed. Provisions for AFDC at appropriate rates of interest are
made in the economic and financial analyses for the project.
(b) Construction Schedules
Construction schedules for the project are based on the system
planning requirement of first power on-line at Watana in 1993 (680
1v1W) and at Devil Canyon in 2002 (600 MW). Assuming a FERC license
to construct the project is received in late 1984, it is essential
that mobilization for construction of diversion and site facili-
ties at Watana be scheduled to commence in early 1985.
The critical construction activity at Watana is the 62 million
cubic yard dam. Seasonal restrictions on placing embankment fill
require a total of seven seasons for completion of this structure.
Timely completion of the excavation and foundation is thus crucial
in the first two years of construction. To insure that this work
is not delayed, construction of a pioneer access road should begin
in 1983, if necessary, prior to receipt of the FERC license. Con-
struction of the remaining transmission, spillway, release, and
power facilities and reservoir impoundment will be appropriately
scheduled to ensure power generation capability in 1993.
Construction power will be obtained by ·installation of an initial
transmission link from the intertie at Gold Creek to Watana within
two years of commencement of construction. In the interim period
diesel generators will be used at the site. To accomplish the de-
s ired schedule for construct ion of Watana, procurement contracts
for site facilities, materials, and equipment should be appropri-
ately scheduled over the 1983-84 period.
Construction of the Devil Canyon dam is currently scheduled to
take five years. Thus, mobilization for diversion and site facil-
ities is scheduled to begin in 1994. Completion of the remaining
transmission, spillway and power facilities, and reservoir im-
poundment will be scheduled for the on-line power date of 2002.
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2.12 -Environmental Impacts and Mitigation Measures
A number of measures have been incorporated into the design of the
Susitna Project to mitigate some of the environmental impacts. Other
measures are also being formulated where necessary in consultation with
concerned agencies.
(a)
(b)
Water Use and Water Quality
Examination of state agency files indicated the major, although
small, users of surface water occur along the Kahiltna and Willow
Creek township grids. Analysis of topographic maps and overlays
showing the specific locations of the appropriations along the
mainstream Susitna River Corridor indicated that neither surface
water diversions from small tributaries nor shallow wells in the
corridor area are likely to be affected by operation of the pro-
posed project.
Impoundment of the Susitna River will change the water quality.
The following parameters will exhibit reductions in values in the
reservoir and downstream reaches as compared to the pre-project
levels: suspended solids, turbidity, color, nutrients, iron, man-
ganese and some trace elements. Both reservoirs will be heat ex-
porters and the downstream reaches of the river will exhibit a
reduced magnitude of seasonal temperature variation. An increase
in downstream temperatures during the winter will result in open
water downstream to Talkeetna, with some impact on fisheries.
Dissolved oxygen concentrations will remain high, at or near sat-
uration, in the upper levels of both reservoirs and downstream in
the river. Although during initial years of operation the reser-
voir nutrient and trace element concentrations will be higher than
at present, potential for eutrophication to develop in either
reservoir is low.
Although water quality changes will be affected by the project,
none of these changes will be significantly adverse and many
changes may be beneficial. No mitigation measures are planned.
Botanical Resources
The primary impacts to vegetation will be through inundation. The
Watana impoundment, at maximum pool elevation, will inundate ap-
proximately 14,691 ha (36,750 acres), which represents 0.9 percent
of the vegetated area of the upper basin. Woodlands, including
open spruce stands and birch forests will be impacted relatively
more than other habitat types. The Devil Canyon reservoir w·lll
flood approximately 3,214 ha (8,035 acres) which is less than 0.2
percent of the vegetation of the upper basin.
Construction of the dams, spillways, camps and utilization of the
borrow areas will remove an additional 2,000 ha (5,000 acres).
Preparation of the right-of-way for the access road wi 11 require
2-49
the clearing of approximately 900 ha (2,250 acres). Some vegeta-
tion may be cleared during transmission line construction, but
this will occur primarily only in areas of tower placement. In
other areas, topping of trees may be required. Operation and
maintenance of the reservoirs may cause minor slope instability
and slumping of the banks.
Mitigation considerations have been incorporated into the planning
process. Proposed construction camps and villages have been la-
c ated in as compact a manner as possible, thereby reducing areas
of vegetation effected. Transmission line routes have been iden-
tified which follow existing rights-of-ways and gentle terrain
wherever possible. The transmission line and access route will
utilize the same corridor for the majority of the way between
Watana and the Parks Highway. Wherever possible, borrow areas
have been located in the proposed impoundment zone, thereby reduc-
ing areas of disturbance outside this zone Clearing of the res-
ervoir prior to inundation will insure use of the resource.
The major additional mitigation technique will be the restoration
of borrow areas, temporary access roads and other areas that may
be disturbed during construction. This will be accomplished
through storing of topsoil, replacing it onto disturbed areas,
contouring, seeding and fertilizing these areas to allow natural
vegetation to regrow. These areas will be monitored and, if
necessary, further mitigation techniques (water bars, terraces,
mulching, etc.) implemented to insure erosion does not occur and
vegetation is established.
(c) Wildlife Resources
Project impacts will occur on big game, furbearers, birds and
non-game mammals.
( i) Big Game
The principal species of big game are moose, caribou, wolf
and wolverine, bear and dall sheep.
-Moose
The Watana impoundment and associated facilities will re-
sult in loss of moose habitat and displacement of those
moose whose home ranges occur primarily within the reser-
voir areas. It is estimated that approximately 400 moose
at Watana and 100 moose at Devil Canyon will be directly
impacted and as many as 800 at Watana and 200 at Devil
Canyon indirectly affected. It is not known how many of
these the surrounding habitat will be able to support.
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Alterations of flows downstream of Devil Canyon has the
potential to affect vegetative succession, thereby im-
pacting moose. However, the amount of available browse
in the Devil Canyon to Talkeetna area is minimal and is
not expected to change significantly. Downstream of
Talkeetna, the inflows of Susitna River tributaries and
11 dampeni ng,. of flow fluctuations will reduce the poten-
tial for changes in vegetation. However, with the reduc-
tion in peak floods, vegetative succession rates may in-
crease. Without mitigation, this could result in a re-
duction in available browse for moose.
The primary method being explored to mitigate impacts to
moose is management of habitats outside the impoundment
zones. This management may involve burning of areas
(stimulating browse growth on which moose feed), logging
operations and other techniques to improve habitat val-
ues, thereby increasing moose populations. In addition,
minimizing areas of disturbance, insuring hunting regula-
tions are enforced and reclaiming borrow areas and other
disturbed areas as described previously wi 11 a 11 reduce
impacts to moose.
-Caribou
The primary potential impact to caribou is through the
intersection of the historically important migration
route across the Susitna River between Deadman and Jay
Creeks. This route is not currently being used; it is
possible caribou will attempt to use it sometime during
the life of the project. Although caribou are excellent
swimmers, mud flats and ice c~nditions on the shore line
of the impoundment which will be present during the
spring migration to the calving grounds may impede their
migration. ·
Insufficient evidence concerning caribou behavior exists
to determine their reaction to the reservoir and the ice.
It is anticipated that the caribou will attempt to cross
(either successfully or with some injury or mortality);
move along the reservoir to a point where a safer cross-
ing is found or; turn bacK. and bear their calves in a
different area. It is considered most l'ikely the caribou
will cross the impoundment safely and impacts should not
be significant.
Mitigation options are being considered. These involve
the monitoring of the spring migration to determine if
the caribou establish new calving grounds and, if so, in-
suring these areas are fully protected from human intru-
sion during the calving period. It is believed this
measure will mitigate the impacts to caribou .
2-51
-Wolf and Wolverine
Construction of the Watana and Devil Canyon reservoirs
will impact wolves and wolverine primarily through loss
of habitat and reduction in prey species. It is believed
6 or 7 wolf packs will be affected as territories of
these packs include areas where moose populations w·ill
likely decline. Approximately 10 to 20 wolverines will
be most directly affected.
The technique currently under consideration to alleviate
these impacts is to in sure an adequate food base for the
wolf and wolverine population. This will be accomplished
primarily through habit at management to increase moose
populations in surrounding areas, as discussed previ-
ously.
-~rown and Black Bear
~rown bear will be primarily affected by the project by
direct habitat loss and human disturbance. Although no
bears• entire home range is within the impoundment zones,
bears will be impacted. The loss of seasonal foraging
areas, particularly in the spring, will likely result in
a reduct ion of the brown bear population. No known dens
will be flooded.
Black bear will be more severely affected. This species
is closely associated with forest habitat, the majority
of which in the project area is in the impoundment zone.
Floading of this forest and lack of suitable adjacent
habitat will considerably reduce the black bear popula-
tion. In addition, 9 known dens will be flooded by the
Watana impoundment and 1 by Devil Canyon.
It is very difficult to mitigate these iQlpacts to bears.
Worker education and access restrictions are being con-
sidered as means to reduce human-caused disturbances.
Habitat management for moose in areas outside the Susitna
basin will be explored to determine if this could also be
used to increase the values of the area as bear habitat.
Presence of a healthy moose population will aid in pro-
viding a food source for bears.
-Dall Sheep
Of 3 sheep herds identified in the upper Susitna basin,
only 1 will be potentially affected. The Watana herd
utilizes a mineral lick on cliffs along Jay Creek. Por-
tions of this lick will be inundated. However, the
greatest port ion of the lick will be exposed aur ing the
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time of heaviest sheep use which is May and June. It is
not known if the sheep will continue to use the lick fol-
lowing creation of the reservoir.
The Watana herd will be monitored. If use of the lick is
discontinued, an artificial lick with similar chemical
composition will be established.
Furbearers
Loss of habitat in the amount described previously and in-
creased trapping and hunting pressure will be the primary
impacts to furbearers. There is also the potential for al-
teration of downstream flows to effect downstream beavers.
Planning of facilities, location of borrow areas in the
reservoir areas, location of the transmission lines and
access roads in common corridors and other techniques as
described previously have been utilized to reduce the areas
disturbed and hence impacts to furbearers. Potential con-
trol of access and enforcement of hunting and trapping reg-
ulations will further reduce these impacts.
(iii) Birds and Non-Game Mammals
The Watana and De vi 1 Canyon impoundment wi 11 inundate 43
km2 (25 mi2) of cliff habitat designated as high qual-
ity. In addition, 4 active and 4 inactive golden eagle
nest sites, 2 active and 1 inactive bald eagle site and 2
inactive raven nest sites will be inundated. Approximately
95 km2 (38 mi2) of forest habitat, which includes the
most productive avian habitat, will be inundated. Red
squirrels, porcupines and other small mammals will also
lose their habitat,. None of these bird or mammal species
are unusual and are present in other areas of Alaska.
The primary loss to be mitigated is that of the bald eagle
nest sites. The creation of two large impoundments may re-
sult in an increase in the eagle population of the area.
To increase chances of this happening, clumps of tall
spruce trees will be left uncut at 1/2-to 1-mile inter-
vals, thereby providing nest sites. If eagles do not use
these, the possibility for erecting artificial nest sites
will be explored. Loss of forest habitat for birds and
small mammals will be mitigated by minimizing and reclaim-
ing areas of disturbance as previously described.
(d) Fisheries
Avenues of impact to fisheries population could occur through
creation of the impoundment and alteration of downstream flows.
2-53
The Watana impoundment will eliminate approximately 80 km (48 mi)
of mainstream river·ine habitat. In addition, a number of tribu-
taries in both the Watana and Devil Canyon areas will be inun-
dated. Inundation of the mainstream is not expected to adversely
affect the fish populations present. The reservoir should provide
new habitat for the existing populations of resident fishes. Fur-
thermore, overwintering areas associated with clear water flows of
the area tributaries will increase, providing habitat for gray-
ling. Existing grayling habitat will be lost, but this may be
compensated for by the production of new overwintering habitat.
Anadromous fish do not occur above Devil Canyon, therefore impacts
to anadromous fish will be limited to those areas downstream of
the proposed impoundment. The primary impact to anadromous fish
will occur in the area between Devil Canyon and Talkeetna and will
result mainly from a reduction in flows. This flow reduction may
reduce the accessibility of sloughs and tributaries utilized by
spawning salmon. The exact extent of this is not yet known. Pre-
liminary estimates of worst case conditions without mitigation in-
dicate impacts will be most severe to chum salmon and least severe
to chinook salmon. Based on the size of the 1981 runs, prelim-
; nary estimates indicate approximately 14,000 sockeye caul d be
lost annually from the harvest, 7,000-8,000 coho lost annually
from the harvest, 68,000 chum salmon lost annually from the har-
vest, and 9,000-10,000 pink salmon (odd year), from an odd year
harvest. Based on long term annual Cook Inlet harvests, the aver-
age annual post-project losses without mitigation would be approx-
imately 2,300 sockeye for an average annual harvest of 1.2 million
fish, 3,850 odd year pink for an average odd year harvest of
148,000 fish, 63,000 -128,000 chum for an average annual harvest
of 630,000 fish, and 12,900 coho for an average annual odd harvest
of 231,000 fish. Data on chinook salmon are not available.
There may be some changes in the river temperature regime and
water quality resulting from reservoir operation, but the impacts
of these are not expected to be significant. Other potential
impacts have been mitigated through site selection and design
features, such as:
-The natural fish migration barrier of Dev-il Canyon precludes
anadromous fish in the upper basin. Thus, the Susitna project
will not block any migrating salmon or inundate spawning areas.
Discharge facilities, capable of passing up to the 1:50-year
flood have been designed with a cone type valve discharge. This
type of discharge will significantly reduce the potential for
nitrogen supersaturation, a condition which can be lethal to
fish.
-A multilevel intake structure has been incorporated into the
Watana dam to allow for partial control of discharge water temp-
erature. This will permit release of water at a temperature
closer to ambient than would normally occur downstream of the
reservoir. This wi1l reduce impacts to fish.
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Other potential mitigation options being considered include:
modification of operating procedures to increase flows down-
stream during critical times of the year; modification of the
existing stream bed by excavating or adding gravel to build
spawning areas; construction of a hatchery to replace any salmon
lost through loss of spawning habitat.
In addition, controlled fueling areas and control of erosion as
descr'ibed previously by revegetation and restoration techniques
will prote~t existing water quality and thereby reduce impacts to
fish.
(e) Historic and Archeaological Resources
Field surveys revealed the following number of historic and arch-
aeological sites will be affected:
-Watana Dam and Impoundment:
Two historic and 24 archaeological sites directly affected and
1 historic and 23 archaeological sites indirectly affected;
Uevil Canyon Dam and Impoundment:
One historical and 7 archaeological sites directly affected, 2
historic and 1 archaeological sites indirectly affected;
-Borrow Areas, Access Route, Transmission Lines:
One historic site and 25 archaeological sites directly affected,
no historic and 7 archaeological site$ indirectly affected.
Historical sites consist primarily of trapper's cabins. Archaeo-
logical sites consisted primarily of remains from hunting activ-
ity, cache pits and house pits. These were largely seasonal camp
sites. Potential impacts would result from disturbance by con-
struction activities and increased access in the area. Mitigation
of impacts to historic and cultural resources will be through
avoidance, preservation or investigation (excavation).
Further studies of cultural resources will be conducted to locate
additional sites that may occur in the area and to determine the
significance (as based on the National Register of Historic Places
criteria 36 CFR 60.6) of these sites. Final siting of access
roads, transmission line towers and facilities associated with the
dam will be done so as to avoid all sites possible. Sites avoided
but subject to indirect impacts through increased access may be
preserved through fencing, stabilization or patrolling. If sites
are determined to be significant and cannot be avoided, excavation
2-55
can be used to move the artifacts to a museum. A cultural re-
source mitigation plan is currently being developed and will be
utilized to insure impacts to cultural resources are minimized.
(f) Socioeconomics
Impacts to the socioeconomics environment will result from in-
creased populations, influx of workers and associated demands for
schools, medical care, and public services. Peak work force will
occur in the 1988-1992 period when approximately 3,500 people will
be employed on the project, with up to 2,500 of these originating
from within the Railbelt region. Peak payrolls during this period
will contribute substantial benefits to the local community.
As a result of the project, the population is expected to increase
over the baseline population forecast for the construction period.
The majority of these people wi 11 live at the work camp and family
village sites. During the peak work period, it is expected total
population influx (including dependents) into communities outside
of the work camp will be approximately 2,300. This includes dir-
ect and indirect work force. Up to 50 percent of this population
increase will be in the Matanuska-Susitna borough with the remain-
der in Anchorage and Fairbanks. Demands for water supply, sewage
treatment, solid waste, law enforcement, education, fire protec-
tion and health care will increase in general by less than 5 per-
cent above baseline conditions projected for the period. This re-
flects the fact that population influx associated with the con-
struction force will represent less than 3 percent of the borough
population in 1989 and less than 2 percent in 19~6.
Housing is projected to be available for the period of population
influx. Talkeetna and Trapper Creek may experience a housing
shortage unless additional homes are built. No businesses will be
displaced by the project; one dwelling may be displaced by the
transmission line in the northern section. Overall socioeconomic
impacts should not be significant.
Socioeconomic impacts will be mitigated primarily through estab-
lishment of a fully contained construction camp and village at the
site. This camp will provide living quarters for the workers,
family living quarters for certain workers, a school, hospital,
recreational facilities (halls, swimming pools, gymnasium, hockey
rink, baseball field) bank, commissary and shopping center. Pres-
ence of a self-contained ca-mp will reduce the need for travel to
surrounding communities and reduce the demand for services from
these communities. Consultation with these communities will occur
as the project proceeds and measures taken to reduce the effects
of the Susitna project on them.
(g) Geology and Soils
Some amount of slope instability will be generated in the Watana
and Uevil Canyon reservoirs as the result of reservoir filling.
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These areas will be primarily in locations where the water level
will be at an intermediate level relative to the valley depth.
Slope failure will be more common in the Watana reservoir because
of the existence of permafrost throughout the reservoir. The
Devil Canyon reservoir is generally in more stable rock, and the
relatively thin overburden is unfrozen in the reach of the river
upstream from the dam. Although skin flows, minor slides, and
beaching will be common in parts of the reservoirs, they will pre-
sent only a visual concern and pose no threat to the project.
Many areas in which sliding does occur will stabilize into beaches
with a steep backslope. Tree root systems left from reservoir
clearing will tend to hold shallow surface slides and in cases
where permafrost exists, may nave a stabilizing influence, since
the mat will hold the soil in place until excess pore pressure has
dissipated. The primary method of mitigating these impacts will
be through standard stabilization, reclamation and revegetation
techniques.
All temporary access roads will be graded, recontoured and seeded
following abandonment. Areas near streams and rivers where ero-
sion may occur will be riprapped during the construction period
and reseeded when construction is complete. Borrow areas will be
excavat~d o~ly as necessary and will either be regraded and seeded
with appropriate species, or if excavation is deep enough, con-
verted to ponds.
To insure success of restoration efforts, a comprehensive restora-
tion and revegetation plan will be developed and implemented to
prevent soil erosion. This plan will include the use of terraces
(if necessary)~ mulch (hay and straw), mulch anchored with a light
asphalt tack, and mats in areas of high erosion potential. Seed-
ing mixtures will be developed to provide the most rapid recovery
possible and include species adapted to all soil and light (shade,
sun, etc.) conditions present at the site. Native seeds will be
used where possible. Seed mixtures may be applied using the hyd-
roseeding techniques which includes a mixture of fertilizer, lime
and seeds. Restoration procedures will be monitored to insure
their efficiency. Any areas showing erosion or where restoration
is not effective will be restored with modified plans.
Rock excavated but not utilized in construct ion will be used as
backfill in borrow areas or disposed of in areas which will be in-
undated by the reservoir.
(h) Land Use, Recreational, and Aesthetic Resources
The Susitna project will alter existing land use recreation and
aesthetic conditions in the upper Susitna Basin. This will be due
both to the presence of the structures and to increased access.
2-57
With increased access, certain land use and recreational activi-
ties are expected to become more intense than at present. Al-
though the present low levels of riverine boating and rafting use
will be displaced, there will be new opportunities for reservoir
boating. Hunting and fishing preserves will increase as larger
areas become available to more people; sightseeing, picnicking and
camping will also increase.
Road access to the damsites from the Parks Highway will likely in-
crease residential and commercial use of the land adjacent to
those areas, resulting in an increase in land values. Presence of
the two dams and reservoirs will modify existing scenery, con-
trasting with the natural landscape present. The access road and
transmission lines will also be prominent features on the land-
scape. Planning during the design of the Susitna project will be
the primary mechanism to insure impacts to land use, recreation
and aesthetics are minimized. Recreational facilities currently
proposed include camp grounds, picnic grounds, boat launches and
hiking trails. Facilities for both primitive and modern camping
will be provided. Commercial facilities such as service stations,
lodging and boat rentals are being considered. All developments
will be designed to blend into the landscape and be screened by
vegetation. Scenic overlooks will be provided on the access
road.
Aesthetic impacts were mitigated primarily in the planning pro-
cess. Aesthetics was an evaluation factor in selecting the access
route and the transmission line route. The powerhouse for genera-
tion is located underground, eliminating a surface facility. Flow
will be maintained between the Devil Canyon dam and discharge out-
let, providing an aesthetically pleasing continuous flow of water.
Restoration and revegetation of borrow areas and other disturbed
areas will also aid in reducing aesthetic impacts.
2.13 -Project Operation
In the year 2010, the projected Railbelt system, with the Susitna on-
line and allowing for existing plant retirements and new additions,
will comprise:
Coal-fired Steam:
Natural Gas GT:
0 i 1 GT:
Uiesel:
Natural Gas CC:
Hydropower:
Total
13 IVlW
326 MW
0 MW
6 IVJW
317 tviW
1440 MW
2102 MW
Under current conditions in the Railbelt, a total of nine utilities
share responsibility for generation and distribution of electric power,
with limited interconnections. When constructed, the 1620 MW Susitna
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project will be the single most significant power source in the system.
Careful consideration is therefore essential of the dispatch and
distribution of power from all sources by the most economical and
reliable means.
(a) Dispatch Control Center
(b)
It is likely that a single entity will be established to perform
the dispatch contra 1 function. Such an entity wi 11 ensure the
allocation of generating plant in the system on a short-term oper-
ation basis and in the long-term, to meet system load demand with
the available generation at minimum cost consistent with the
security of supply. A system Dispatch Control Center wi 11 be
established for operation purposes near Willow.
One of the most important functions of the Control Center is the
accurate forecasting of the 1 oad demands in the various areas of
the system. Area demand forecasts up to 8 hours ahead of unit
loading are based on regional short-range weather forecasts for an
estimate of heating and lighting demands plus light or heavy in-
dustry loads. Short-term forecasting up to 1 or 2 hours ahead is
more difficult and remains the key factor to the secure and eco-
nomic operation of the system. Based on the demand, basic power
transfers between areas and an allowance for reserve, the tenta-
tive amount of generating plant is determined, taking into consid-
eration the reservoir regulation plans of the hydro plants.
The fastest response in system generation wi 11 come from the hydro
units. The large hydro units at Watana and Devil Canyon on spin-
ning reserve can respond in the turbining mode within 30 seconds.
This is one of the particularly important advantages of the
Susitna hydro units. A Watana Area Control Center will also be
established. This will be equipped with a computer-aided control
system, allowing a minimum of highly trained and skilled operators
to perform the control and supervision of Watana and Devil Canyon
plants from a single control room.
Susitna Project Operation
Substantial seasonal as well as over-the-year regulation of the
river flow is achieved with the two reservoirs. If the reservoirs
are operated to produce maximum energy matched to Railbelt system
demands, average energy potential of Watana development is 3,450
GWh, and that of Devil Canyon development is 3,340 GWh. These
estimates are based on simulations using the 32-year period of
flow records. Firm annual energy for the project, based on the
FERC definition is 5,400 GWh, with an estimated recurrence fre-
quency of 1 in 70 years. Expressed another way, the firm energy,
as defined, may fall short of its value by about 5 percent once in
300 years. This is, again, a conservative interpretation of the
FERC definition. The monthly distribution of firm annual energy
as simulated in the reservoir operation has been used in system
generation planning studies as a basis for reliability determina-
tions.
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.(c) Downstream Flows
1"1inimum monthly flows that must be maintained in the river below
the dam during filling were established in consultation with fish-
eries and other environmental study groups and agencies. With the
minimum monthly flow that is considered acceptable for river main-
tenance and fisheries requirements during the filling period, it
will take at least 2-1/2 years of average streamflow to fill the
Watana reservoir. It may be noted that the placement of the fill
dam critically controls the reservoir filling in average stream-
flow years and restricts earlier filling should wet years be
experienced.
With Watana reservoir in operation, the filling of the Devil Can-
yon reservoir is relatively easily accomplished. Average monthly
power flows from Watana in the months October through December in
a single year will fill the reservoir while maintaining the mini-
mum downstream flow requirements.
During operation of the project, average flows released in the
critical summer salmon spawning periods are not considered to be
sufficient to maintain the current spawning areas. Appropriate
mitigation measures are proposed to compensate for these impacts
on fisheries.
{d) Plant Operation and Maintenance
A comprehensive system of monitoring of performance of all project
functions and structures will be instituted.
Watana and Devil Canyon power plants are each provided with work-
shops to facilitate the normal maintenance needs of each plant.
The workshop block includes operations for fitting and machining,
welding, electrical, and relay ·instrumentation, with adequate
stores for tools and spare parts. The Watana power plant will be
provided additionally with surface maintenance and central storage
facilities to cater to the needs of both plants.
Maintenance operation planning of both plants are centralized at
Watana. Staff wll be normally located at Watana and housed at the
operators' village at Watana. With centralized control at Watana,
the Devil Canyon plant will not have a resident operating and
maintenance staff. Proper road and transport facilities should be
maintained between Watana and Devil Canyon to facilitate movement
of personnel and/or equipment between the plants.
2.14 -Economic and Financial Evaluation
The major factors in the economic evaluation of Susitna are the rate of
real escalation for the fuels which are the main cost component of the
thermal alternatives to Sus itna. In broad conformity with other au-
thoritative forecasts, the estimated escalation of coal, gas, and oil
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was taken as 2.6 percent, ~-5 percent, and 2.0 percent, respectively
until 2000. From 2000 until 2010, the escalation for coal was taken as
1.2 percent and for gas and oil, 2.0 percent. Similarly in accordance
with accepted authorities, the discount rate for evaluating future ben-
efits and costs was taken as 3 percent in real terms.
Generation planning studies were conducted using a consistent set of
fuel prices for thermal power generation alternatives and of capital
and operation maintenance costs established for Susitna and alternative
plant. A generation planning, model (OGP5), which is widely used for
system studies of the type performed for Susitna, was employed to de-
termine net economic benefits. These were modeled for the period to
2010 for systems scenarios 11 With 11 and 11 Without 11 Sus itna and the 1 ong-
term increment in the estimated present worth was assessed to 2051.
The pattern of generation expansion investments was determined for a
11 With 11 Susitna plan involving 680 MW of capacity coming on-1 ine at
Watana with an addition of 600 MW at Devil Canyon in ZOO~. A later
addition of 340 I'~IW at Watana would be justified by standing and spin-
ning reserve requirements. The comparable 11 Without 11 Susitna plan calls
for three 200 rviW coal-fired plants fueled from Beluga installed in
1993, 1994, and 2007 and a single 200 MW plant at Nenana, using Healy
coal, in 1996, together with 970 MW of gas-fired combustion turbines
during the planning period.
The Probability Assessment analyzed the system costs of generation for
the Railbelt on a 11 With 11 and 11 Without" Susitna basis and concluded that
the expected value of the net present worth savings from Susitna were
$1.45 billion with a 36 percent probability of being less than $0.5
billion.
Risk Analyses which address the major natural, construction, and capi-
tal cost risks concluded that the probability that the project con-
struction cost estimate would not be exceeded was 73 percent. The ex-
pected values of the actual costs are 90 percent of the project esti-
mate for Watana and 92 percent for Devil Canyon. There is a 65 percent
probability that the Watana stage of the prDject will be completed
prior'to schedule in 1993,
In the Marketing Assessment the problem of integrating the Susitna out-
put into the Ra i 1 belt market as Watana comes on-stream in 1993 and
Devil Canyon in 2002 was reviewed. The maximum 11 entry price" of the
Watana energy was identified at 145 mills/kWh (in 1993}. if it is to be
competitive with the energy costs of generation from the best thermal
option. When Watana comes on-line its output will displace existing
generating capacity on the interconnected Railbelt utility system.
While initially the avoided costs of the displaced energy generation
will be relatively low, inflation and escalation strongly influence
thermal power fuels and if the allowance is subsequently made for the
investment costs arising from plant expansion to provide comparable al-
ternative service to Susitna, the predominantly hydroelectric system
can be shown to offer steadily increasing overall cost savings. The
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wholesale energy cost and marketability of Susitna output will be
strongly influenced by the appropriations made by the State of Alaska
through the 11 Power Develop11ent Fund".
On the assumption that residual revenue bond financing will be required
to supplement state appropriations of funds for construction of
Susitna, the tax-exempt status of the consumer utilities is a major
consideration. This, combined with the need for sufficient financial
robustness of the entities entering into contracts to support debt
financing, suggests the need for financial restructuring of the
Railbelt utilities.
It is recommended that the precontracts for the purchase of Sus itna
output at the wholesale energy price determined by legislation be ar-
ranged with the major Railbelt utilities as a precondition of proceed-
ing with the construct ion of Sus itna, and as a means of ensuring the
least cost energy for the system as a whole.
In the Financial Evaluation the marketing and Ol:lP5 analysis of the
price at which Susitna energy would need to be marketed to be viable in
establishes this as about 145 mills/kWh in 1993. The various financing
options that would make this possible are considered. These range from
a 100 percent state appropriation of the total capital cost ($5.1 bil-
lion in 1~82 dollars) to a min-imum level at which debt service cover
and competitive energy pricing would be met. It is concluded that a
state appropriation of $2.3 billion (in 1982 dollars) with residual
financing from bonds would make Susitna output competitive with the
price of 145 mi 11 s/kWh and ultimately produce very 1 arge subsequent
savings to Alaskan consumers compared with the best thermal option.
The long-term savings from Susitna are also such that the state appro-
priation could be recovered with a better than 10 percent rate of
return.
In the Financial Risk Analysis the specific and aggregate financing
risks are assessed. It is concluded ·in the $2.3 billion state appro-
priation case that the probability of the bond financing requirements
exceeding $2.5 billion (compared with a forecast requirement of $1.7
billion) is less than 12 percent. The probability of the project not
being able to meet fully its debt service cover in 1996 is 22 percent.
2.15 -Conclusions and Recommendations
The investigations presented in this report covering a comprehensive
range of studies, in numerous and varied disciplines, in many different
locations in the North America as well as Alaska, have allowed an ob-
jective evaluation to be made of the proposed Susitna Hydroelectric
Project. The essential conclusions of this evaluation are that the
project is technically feasible, and economically viable. The safety
of the population in the vicinity of the project will not be impaired
and the unavoidable impacts which this large project will cause on the
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environment will not be unduly severe and can be adequately mitigated.
Financing of the project is also feasible with state assistance at
acceptable risk to consumers in the Railbelt region.
It is recommended that the state authorize the filing of a FEKC license
application to construct the project and proceed with all permitting,
environmental studies, and engineering activities necessary to maintain
the project schedule. A dec is ion to construct the Watana project
should be periodically reviewed in light of additional engineering,
cost, environmental and financial information generated during the
design phase.
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3 -SCOPE OF WORK
3.1 -Evolution of Plan of Study
The original Plan of Study (POS) for the Susitna Project Feasibility
assessment was submitted by Acres on September 11, 1979 in response to
the Request for Proposal issued on June 25, 1979, by Mr. Eric Youl d,
Executive Director of the Alaska Power Authority.
Acres initiated study planning activities in accordance with the orlgl-
nal POS under the terms of a contract with the Power Authority dated
December 19, 1979. In response to suggestions from interested citizens
as well as public and private organizations and agencies, a number of
revisions were made to the original POS. A revised POS was issued for
further public review and comment on February 4, 1980, prior to com-
mencement of major portions of the work (1). Further revisions to the
POS were subsequently issued September, 1980 (Revision 1,[2]), Decem-
ber, 1981 (Revision 2, [3]) and February, 1982 (Revision 3, [4]).
(a) POS Revisions
The original Acres POS was prepared to include a wide range of
comprehensive studies necessary to assess the techni ca 1 and eco-
nomic feasibility of the project and the environmental impacts
which construction of such a project would cause. Details of the
revised POS are presented in subsequent sections.
Revisions which were made to respond to questions and concerns
raised by reviewers included:
-To ensure objectivity in Railbelt el.ectric load forecasting and
generation planning, the State of Alaska entered into separate
contracts with the Institute of Social and Economic Research
(ISER) to develop independent forecasts, and with Battelle
Northwest to study alternatives for meeting future Railbelt
electric energy requirements;
Significant increases in the amount of effort devoted to fisher-
ies and other environmental studies were introduced in response
to comments from the Alaska Department of Fish and Game and the
U.S. Fish and Wildlife Service;
-To ensure objectivity in the conduct of the public participation
program, it was decided that the public participation aspects of
the study should be conducted under the direction of the Alaska
Power Authority rather than by Acres;
-The level of effort associated with marketing and finance stud-
ies was reduced in the first phase of the study, thereby defer-
ring certain financing subtasks until initial questions as to
3-1
project viability and concept had been more thoroughly addres-
sed;
-Some changes were made in logistical and administrative support
efforts both to accommodate the increased level of environmental
activity and to ensure efficiency and responsiveness as the
study progressed;
-Additional effort was prescribed for in-stream flow studies
downstream of Talkeetna in response to concerns expressed by the
Alaska Department of Natural Resources; and
-License application preparation and submittal was postponed
three months to allow additional data collection and analysis
and addjtional opportunity for agency consultation in developing
mitigation plans.
(b) Basis of POS
Prior to preparation of the Acres POS, numerous studies of the hy-
droelectric potential of the Susitna River Basin had culminated in
a major pre-feasibility study by the U.S. Army Corps of Engineers
(COE) which led to a recommendation in 1976 by the Chief of Engi-
neers that the Susitna Project be authorized. The COE plan recom-
mended two high dams, the first of which would be built as a mas-
sive earthfill gravity structure 810 feet in height at the Watana
site. The second COE dam was to be a 635-foot-high thin arch con-
crete structure at the Devi 1 Canyon gorge, more than 30 miles
downstream.
By June 1978, the COE had prepared a plan of study describing a
program leading to completion of a detailed feasibility study for
the project (5). Further investigations by the COE confirmed the
adequacy of the Watana site, though they did reveal that some de-
sign changes were required.
Data, analyses, and reports collected and prepared by the COE were
used throughout the course of the work undertaken by Acres. The
Acres POS comprised an initial series of tasks and subtasks, aimed
at selecting an appropriate concept for development, if develop-
ment were found appropriate, by the end of the first year of
study. This was followed by a more detailed series of tasks and
subtasks to prepare and assess the feasibility of designs for each
site development.
(c) Specific Objectives of Study
As a basis for structuring the scope of work for the avera ll
study, the three primary objectives of feasibility assessment, en-
vironmental evaluation and preparation of FERC license were fur-
ther subdivided into a series of more specific objectives, as fal-
lows:
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Determine the future electric power and energy needs of the
south-central Railbelt area, based upon independent analysis by
ISER, and later Battelle;
-Assess alternative means of meeting the load requirements of the
Railbelt area, consistent with independent analyses by Battelle;
-Prepare an optimal development plan for the Susitna Project
wherein power costs and probable impacts are minimized, safety
is enhanced, and financing is achievable;
-Establish a definitive estimate of the total cost of bringing
power on-1 ine, together with a statement of cash flow require-
ments;
Evaluate the physical, economic, and financial risks of the
Susitna Project and determine ways and means to avoid or mini-
mize their consequences;
-Evaluate existing environmental and social factors as they now
exist in the proposed project area, assess the impacts of the
proposed project, enhance en vi ronmenta 1 va 1 ues to the extent
possible, and recommend mitigating measures;
Estimate the annual system power costs in the Railbelt with and
without the project, study the integration of Susitna power into
the Railbelt utility system, and assess power marketability;
-Subject to confirmation of feasibility and State authorization
to proceed, prepare a complete license application and file this
with the Federal Energy Regulatory Commission;
-Ensure that the needs and desires of the public are known, keep
interested parties and the public informed, and afford an oppor-
tunity for public participation in the study process; and
-Determine an optimal program for achieving financing, including
resolution of issues regarding tax-exempt status of bonds which
may later be offered.
In formulating a logical approach to the study of a major hydro-
electric development in a relatively hostile climate and environ-
mentally sensitive region, it was necessary to identify the par-
ticular problems to be addressed and to place these in proper per-
spective with the more routine elements of technical and economic
feasibility assessment. To ensure an optimal development, it was
essential to recognize and allow for all constraints imposed, and
address such vital issues as environmental acceptabi 1 ity at the
proper stage to allow it to be considered adequately through pub-
lic participation and other processes to satisfy licensing proced-
ures. The financial viability of the project is also a vitally
important consideration which lies beyond the strict technical and
economic parameters of the proposed deve 1 opment. The approach
3-3
taken in the overall studies was such that a confident determina-
tion of the financibility of the project could be accomplished.
A summary of the activities undertaken in the twelve major tasks
is presented in the following sections.
3.2 -Task 1: Power Studies
As conceived in the February, 1980 issue of the POS, the objectives of
this Task were essentially defined as the determination of the need for
power in the south-central Alaska Railbelt region and the development
of a technically, economically and environmentally feasible plan to
meet that need. Subsequent revisions to the POS resulted in signifi-
cant modifications to these objectives and the corresponding scope of
work.
(a) Demand Forecasts for Development Selection
The derivation of forecasts of demand for electric energy in the
Railbelt was based on work performed for the Power Authority and
the state in early 1980 by the ISER. Reviews of ISER•s work were
the subject of a report issued in December, 1980 (6), which formed
the basis of initial Susitna development selection studies. This
report dealt with energy forecasts alone. The determination of
the corresponding peak load forecasts appropriate for use in gen-
eration planning studies was the subject of further studies culmi-
nating in a second report also issued in December, 1980 (7).
(b) POS Revision 1
As of June 6, 1980, following changes -in State Legislation, all
Task 1 work relating to study of Susitna alternatives by Acres was
terminated, with the exception of the review of ISER work and der-
ivation of peak load forecasts. Revision 1 to the POS to formal-
ize these scope revisions, was issued in September, 1980 (2). A
final Task 1 Closeout Report to document the results of partially
completed studies of alternatives was issued in September, 1980
( 8) .
As a result of these legislative changes, the State of Alaska sel~
ected Battelle Pacific Northwest Laboratories to undertake an in-
dependent study of alternatives for meeting future Railbelt region
demftnd for electricity. The scope of the Battelle study includes
an update of the ISER forecast for electric energy demand as well
as an independent assessment of peak 1 oad. The incorporation of
the results of these studies into Susitna planning studies in late
1981, is discussed under Task 6.
3.3 -Task 2: Surveys and Site Facilities
The essential objective of Task 2 was to provide all necessary logisti-
cal support and other related services for successful accomplishment of
field activities necessary for completion of the feas-ibility studies
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and license application preparation during the January, 1980 through
June, 1982 period. Although the scope of this Task was expanded from
time-to-time during the period of the study, the basic nature of the
work did not significantly change.
These services included:
-Procurement, erection, and continued operation of camps with associ-
ated permitting requirements;
Appropriate provisions for surface and air transportation, communica-
tions, and fuel supplies;
-Aerial, ground and hydrographic surveys;
-Access roads studies;
Reservoir area reconnaissance, slope stability, and erosion studies;
and
-Reservoir clearing and disposal studies.
(a) Field Accommodation
(b)
A 40-man camp supplied by Arctic Structures Inc. of Palmer,
Alaska, was erected and placed in service by March, 1980. The
camp building modules were designed in compliance with state ordi-
nances and requirements for use in an arctic environment. The
modules together with other equipment and materials necessary for
camp construction were transported to the site by means of Catco
Rolligon vehicles, in strict compliance with federal and state
permit restrictions, during the winter months when there was ade-
quate snow cover on the ground.
The camp comprised bedroom units, associated bathroom, kitchen/
dining and recreation units, as well as fuel/materials storage
f ac i 1 it i es, and was used throughout the study period to house
personnel engaged in numerous field activities. Self-contained
water supply, electric power generation, sewage treatment, garbage
disposal and helicopter landing facilities completed the installa-
tion. During peak activity perioas, particularly during the
summer months, personnel were also accornrnodated at three local
hunting lodges and in more remote tent camps.
Transportation Arrangements
With the exception of initial surface transportation of camp mod-
ules and construction equipment and materials, all transportation
of personnel and resupply of materials to the study area was ac-
complished by means of helicopters and small fixed-wing aircraft.
Contractual arrangements were made at various times during the
conduct of the study with five different companies for the supply
and operation of helicopters and fixed-wing aircraft. These
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aircraft operated mainly from Anchorage and Talkeetna, the fixed-
wing aircraft utilizing existing landing strips at those locations
together with existing strips in the project area and lakes. Hel-
icopters used helicopter pads constructed at the camp and key
working areas.
An effective system of radio and telephone communications was es-
tablished to facilitate the operation of the aircraft and the camp
itself. At peak periods, air transportation requirements for per-
sonnel traveling to numerous different locations on a daily basis,
and for relocation of drilling and other heavy equipment, put a
severe strain on logistical planning efforts. Particular atten-
tion was paid to safety and personnel security in all aircraft and
helicopter operations.
(c) Surveys
Detailed topographic surveys were undertaken for the entire area
of the project including reservoirs, damsites, access and trans-
mission line corridors. Hydrographic surveys of important reaches
of the Susitna River were also performed as a basis for Task 3 hy-
drologic and hydraulic design studies. These surveys were based
on aerial photography and a comprehensive system of horizontal and
vertical ground control which was established to complement USGS
and Corps of Engineers mapping which already existed for parts of
the project area.
The bulk of the field survey work was undertaken during the first
18 months of the study period. The processing and reduction of
data for production of topographic maps was essentially completed
by late 1981. The scheduling of field work and aerial photography
was made particularly difficult by the need to avoid periods of
snow cover and tree foliage. Susitna River hydrographic surveys
were also hazardous, particularly at Devil Canyon. Detailed re-
sults of the mapping were provided to the National Geodetic Survey
for incorporation into their overall data base for the State of
Alaska, and were used as a basis for design and feasibility asses-
sment of the Susitna project.
(d) Access Roads
A comprehensive design and feasibility assessment of alternative
access corridors and routes was undertaken in Task 2. The objec-
tive of this study was to select an appropriate mode and route for
access to the proposed Susitna development and a plan for imple-
mentation to meet the project schedule requirements. This work
was undertaken in parallel with associated engineering, environ-
mental, cost and scheduling studies in Tasks 6, 7, and 9.
The final product of this study is a report entitled 11 Access Plan-
ning Study'• dated January, 1982 (9).
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(e) Reservoir Studies
Reconnaissance of the Watana and Devil Canyon reservoir areas was
undertaken first by means of aerial photography and overflying,
and finally by on-the-ground inspection. The purpose of these
studies was to identify areas of potential instability or suscep-
tibility to erosion during filling and subsequent operation of the
reservoirs.
Basic information acquired during this phase of the study was used
as input to environmental studies of impacts of the reservoir im-
poundment. The information was also used as a basis for determin-
ation of requirements and costs for reservoir clearing and dis-
posal of materials. A further activity undertaken during the
course of the study was to identify the ownership and status of
land in and adjoining the project and associated access and trans-
mission corridors. This information was duly incorporated into
the appropriate project planning and permitting processes.
3.4 -Task 3: Hydrology
The original objective and scope of Task 3, as proposed in the February
1980 POS, was to undertake ~11 hydrologic, climatic, hydraulic and ice
studies necessary to complete the feasibility assessment and designs
for the Susitn~ Prqject as a basis for the FERC license application.
Under Revision 2 of the POS, which was issued in December, 1981, the
scope of Task 3 was expanded to include additional hydrologic and de-
sign studies in response to perceived public concerns. Work commenced
in this Task early in 1980 with the initiation of data collection and
monitoring and continued throughout the study period. Comprehensive
results of Task 3 studies are presented in Appendix A to this report.
(a) P~ta Compilation
(b)
A comprehensive network of climatic and hydrologic data collection
systems with appropriate processing and distribution arrangements
were established early in 1980 and oper~ted for the duration of
the study period. These data provided a continuing basis of
hydrologic and hydraulic studies and designs for assessment of
project feasibility and environmental impact.
Water Resources and Flood Studies
These studies involved the processing of available and newly ac-
qt,lired climatic and hydrologic date;~ for purposes of determination
of streamflow availability for hydroelectric generation, reservoir
operation simulations, and estimates of flood frequency and magni-
tude. These studies then formed the basis of project economic
planning analysis and spillway designs under Task 6. Under Revis-
ion 2 to the POS issued in December, 1981, in response to per-
ceived public concerns, the scope of this activity was expanded.
Additional activities included a re-evaluation of the probable
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maximum flood on the basis of more comprehensive data and the dam
break analysis.
(c) Hydraulic and Ice Studies
The scope of these studies included the determination of water
levels and ice cover conditions upstream and downstream from the
project sites for pre-and post-project conditions, making use of
available and newly acquired hydrologic and hydrographic survey
data. These studies were used as a basis for establishment of
reservoir freeboard and operating constraints, and pre-and post-
project water temperature and quality conditions as input to fish-
eries and related studies under Task 7.
(d) Sedimentation and River Morphology
These studies were undertaken to determine the rate of sediment
accumulation in the proposed reservoirs and prediction of the ef-
fects of project operation in the downstream river channel mor-
phology from Devil Canyon to below Talkeetna. Appropriate river
sampling procedures were established during the study period as a
basis for these evaluations.
(e) Transmission and Access Studies
Climatic design criteria, including wind velocity and ice accumu-
lation estimates, were developed on the basis of available cli-
matic data and observations for transmission line designs together
with evaluation of design flood requirements for access road
stream crossings.
3.5 -Task 4: Seismic Studies
This Task involved a wide range of field and office studies aimed at
developing an understanding of the seismic setting and potential earth-
quake mechanisms of the region and determining the seismic design cri-
teria for the structures to be built. The original February, 1980 POS
for Task 4 included a two-year program of activities for 1980 and 1981
to meet the study objectives. Some expansion of field activities in_
1981 was made under Revision 2 of the POS.
(a) 1980 Studies
The essential purpose of the 1980 studies was to install and oper-
ate a microseismic network in the project area and to identify,
from historical and available remote sensing imagery data, poten-
tial tectonic features to be considered in establishing the seis-
mic setting of the project. The 1980 studies also included a pre-
liminary geologic reconnaissance, an assessment of reservoir-
induced seismicity, and preparation of a report (10).
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(b) 1981 Studies
The 1981 studies involved a more detailed investigation and eval-
uation of a number of potential tectonic features identified in
the 1980 studies. The work involved a large degree of field map-
ping of quaternary geology in the project area and trenching of
significant features. Evaluation efforts included detailed stud-
ies of regional and similar worldwide earthquake characteristics,
estimation of potential earthquake magnitudes and probability of
occurrence associated with important tectonic features, an assess-
ment of the corresponding potential ground motions, and the devel-
opment of appropriate earthquake design criteria for use in design
of project structures. A manual was also prepared for installa-
tion and cant i nued operation of a permanent seismic monitoring
system.
The results of the 1981 studies were incorporated into a compre-
hensive report (11).
3.6 -Task 5: Geotechnical Exploration
The objective of Task 5 as conceived in the February, 1980 POS was to
determine the surface and subsurface geology and geotechnical condi-
tions for the feasibility studies of the proposed Susitna Hydroelectric
Project, including the access roads and the transmission lines. This
was accomplished by a comprehensive program of field exploration, geo-
technical evaluation, and dam studies over more than two years, com-
mencing in early 1980. The scope of Task 5 was increased in 1982 "in
terms of additional field work under Revision 2 to the POS, to respond
to concerns raised by the Power Authority•s external review board.
(a) Field Work Programs
Programs of field work were developed and undertaken in summer and
winter seasons in both 1980 and 1981, each of which culminated in
a detailed report (12, 13). The field work was essentially de-
signed to provide input to the Task 6 design studies and to pro-
vide support to the Task 4 studies.
A wide range of geotechnical exploration was undertaken at the
De vi 1 Canyon and Watana s ltes, reservoirs, and access roads and
transmission line routes, together with comprehensive evaluation
and documentation of the results. This work included preparation
of:
-Geologic maps, both regional and site specific;
-Geologic sections;
-Descriptive and graphic borehole logs;
-Descriptive test trench logs;
-Field inspection borehole and test trench logs;
Photogeologic maps;
Borehole rock core photographs;
3-9
Low level air photointerpretation;
-Seismic and resistivity bedrock profiles;
-Radar imagery interpretation maps;
-Geotechni ca 1 exp 1 oration program summaries for proposed struc-
tures and material borrow areas (1980, 1981, 1982);
-Data summaries for:
-In-hole seismic testing.
-Borehole camera studies.
-Laboratory testing of construction materials.
(b) 1980 Program
The geotechnical exploration programs in the field were severely
constrained by difficulties of access and maneuverability of
equipment imposed by weather conditions and the requirements for
environmental preservation.
The 1980 geotechnical exploration program was designed to identify
and investigate in limited detail those geological and geotech-
nical conditions which were likely to significantly affect the
feasibility of the proposed dam projects. Limited preplanning op-
portunities, requirements for permits from state regulatory agen-
cies, and climatic constraints were such that investigations in
1980 were somewhat limited in scope, and the data limited in de-
tail. Emphasis was therefore placed on identifying and investi-
gating to the maximum extent the most adverse geotechnical condi-
tions encountered.
(c) 1981 Program
The objectives of the 1981 geotechnical exploration program were
to investigate in more detail those geological and geotechnical
conditions, both general and adverse, which significantly affected
the design and construction of the proposed dam projects, and to
obtain the maximum amount of geotechnical design data possible in
the time available. The scope of the exploratory work and the
data produced in 1981 was by no means intended to be fully compre-
hensive for project designs, but rather to establish with reason-
able confidence the feasibility and total cost of the project, ac-
cess roads, and transmission lines. The exploratory programs in
subsequent years will be yet more detailed, and aimed at providing
greater certainty in the design of major dams and structures with
a view towards further ensuring the safety of structures while
minimizing potential project cost overruns because of unforeseen
geotechnical design conditions.
3.7 -Task 6: Design Development
As originally conceived in the February, 1980 POS, this Task involved
the initial planning studies and selection of an appropriate Susitna
development, including the evaluation, analysis and review of all pre-
vious engineering studies related to hydroelectric development of the
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Upper Susitna River Basin, and the development of preliminary engineer-
ing design and cost information for the selected Watana and Devil Can-
yon Dam projects with all associated intake, outlet works, spillways,
and power facilities to allow preparation of the project feasibility
report.
Further expansions of the scope of Task 6 studies were included in Re-
visions 1 and 2 to the POS to give added consideration to Railbelt re-
gion generation planning studies with and without the proposed Susitna
project, and to develop additional estimates of project construction
cost for planning purposes.
Activities under Task 6 were essentially divided into two phases. The
first was devoted to consideration of alternatives and selection of an
optimum plan for development of the Susitna River Basin, the second to
preliminary design and assessment of the technical and economic feasi-
bility of the selected development.
(a) Development Selection
The first phase of studies culminated in a recommended Susitna
Basin development plan in March, 1981 (14). These studies in-
volved consideration of development of all identifiable hydroelec-
tric sites in the Susitna River Basin 80 as well as elsewhere in
the Railbelt. Alternatives involving staged developments were al-
so evaluated. Preliminary comparisons were undertaken on the
basis of conceptual project designs at each site in terms of tech-
nical, economic, and environmental aspects.
Early consideration was given to the technical feasibility of con-
struction of an arch dam at the Devil Canyon site, as proposed in
earlier studies by the USBR and COE. Alternative Susitna develop-
ments, involving construction of tunnels up to 30 miles long in
lieu of a Devil Canyon dam and reservoir, were also evaluated
( 15) .
(b) Feasibility Assessments
The second phase of studies is essentially the subject matter of
this report. The work undertaken involved a comprehensive evalua-
tion of the project developments at the Watana and Devi 1 Canyon
sites. These studies included consideration and selection of opt-
imum solutions for a variety of project arrangements as well as
alternatives for major structures such as dams, spillways, power
facilities, and river diversion schemes at each site, in terms of
technical feasibility, cost, and environmental impact. Appropri-
ate criteria were established for hydraulic seismic, geotechnical
and structural designs on the basis of the data developed under
other areas of the study. These designs were also intended to be
used for inclusion in the FERC license application.
3-11
3.8 -Task 7: Environmental Studies
The overall objective of the environmental studies was to describe the
existing environmental conditions, evaluate alternatives in light of
the existing conditions and, for the selected alternatives, predict
future conditions with and without the proposed project so that changes
(impacts) caused by the project may be assessed.
(a) Basis of Studies
To accomplish the overall study objectives, the following activi-
ties were undertaken by the environmental study team:
-Participation with the design team in selection of the best al-
ternatives for power generation, access road and site facility
locations, and power transmission corridor based on the environ-
mental impact of the proposed facility;
-Preparation of the exhibits required to support the FERC license
application;
-Responses to inqu1nes from local, state, and federal agencies,
and public participants at the request of the Power Authority;
-Appropriate execution and coordination of field and office ac-
tivities for all environmental baseline studies and impact
assessment;
-Monitoring of all field activities for environmental acceptabil-
ity; and
Development of environmental mitigation plan in consultation
with the design team and external agencies.
Intensive baseline and impact-related investigations were per-
formed over a two year period with the work progressing from gen-
eral to specific as the project definition was developed. Because
of the magnitude of the proposed action, the life cycle of some of
the resources to be impacted, and the time required to evaluate.
alternatives and develop design specifications, it was recognized
that some environmental studies should be continued beyond the
time of license application. Thus, one important element of the
early studies was to initiate baseline studies and to develop de-
tailed plans of study for the further environmental impact analy-
sis that will be completed after the license application submis-
sion, but prior to a final FERC decision on the license applica-
tion.
(b) Studies Undertaken
The environmental program was primarily designed to evaluate the
Susitna Hydroelectric Project and associated facilities, with
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respect to environmental impacts. To accomplish this, a compre-
hensive program of field and office studies was developed in the
February, 1980 POS to address the following topics:
-Water Resources (Quality) Analysis:
-Socioecnomic Analysis;
-Cultural Resource Investigation;
-Land Use Analysis;
-Recreation Planning;
-Susitna Transmission Corridor Assessment;
-Fish Ecology Studies;
-Wildlife Ecology Studies;
-Plant Ecology Studies;
-Geological Analysis;
-Access Road Environmental Analysis; and
-Preparation of FERC License Application Environmental Exhibits.
The scope was also structured to provide appropriate coordination
of the various environmental study topics and groups and to moni-
tor field activities for environmental acceptability.
In· response to concerns expressed by some agencies, the scope of
work was further expanded in Revision 2 to the POS to provide for
additional data collection and evaluation activities for geomor-
phology changes in the lower Susitna River, w~ter quality, further
quantification of project socioeconomic impacts, inclusion of
sociocultural impact assessments, dissolved gas investigations,
downstream river plant ecology assessments, and alternative access
corridor environmental assessments.
Periodic progress reports summarizing the activities, results, and
cone 1 usi ons of the studies performed ;were issued at appropriate
stages of the major study topics. These reports formed the basis
of submittals to various state and federal agencies, whose re-
sponses have been and will continue to be considered in formula-
tion of Susitna project designs and in the FERC license applica-
tion.
3.9 -Task 8: Transmission
The work undertaken under Task 8 was essentially to consider alterna-
tive transmission corridors, select the transmission route, and produce
conceptual designs and cost estimates for the feasibility report and
FERC license application for the following components of the Susitna
Project:
-Transmission line linking the project damsites to Fairbanks and
Anchorage, with potential intermediate substations to feed local com-
munities;
-Substations, with particular reference to the two major terminals
serving Fairbanks and Anchorage, together with a suitable design for
intermediate load points; and
3-13
-Dispatch center and communications system.
The basic approach to the work in this task included review of earlier
reports prepared by IECO and the COE with respect to their approach and
their level of detail. Following this, more detailed study and concep-
tual design was undertaken up to a level appropriate for the FERC li-
cense submission and for assessment of basic technical and economic
feasibility.
Included in this work was the utilization of geologic and climatologic
field data obtained during the study period.
(a) Corridor Selection Studies
The main thrust of studies undertaken through early 1981 involved
selection and evaluation of alternative transmission corridors for
the proposed Susitna project (16). Associated with this work were
studies related to transmission lines for power generation altern-
atives also under consideration, together with preliminary assess-
ments of design requirements for the Susitna Transmission system.
(b) Transmission Line Design and System Studies
Subsequent studies involved transmission line route selection,
transmission system analysis, and development of basic design in-
formation dealing with the following aspects:
-Transmission Line Voltage Level
Tower types;
Route map;
Conductor data;
. Insulation levels;
Construction access;
. Construction schedule; and
Cost estimates.
-Substations
Single-line diagrams for each main type of substation;
General arrangement drawings;
Transformer criteria;
Circuit-breaker criteria;
. Outline of relay protection philosophy; and
Cost estimates.
-Dispatch Center and Communications
. Location and size of center;
Level of automation proposed for remote stations;
Extent of real-time functions required;
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Type of communication channel proposed together with appropri-
ate data transmission rates;
Basic type of software; and
Man-Machine interface.
3.10 -Task 9: Construction Cost Estimates and Schedules
The basis of Task 9 was the development of comprehensive, contractor-
type, construction cost estimates for each major element of the pro-
posed Susitna Hydroelectric Project, detailed engineering and construc-
tion schedules, and an associated analysis of potential contingency
constraints and impacts.
The development of these estimates and schedules took place in parallel
with design development, and included assembly and preparation of:
-Cost and schedule data;
Preliminary cost estimates;
-Cost estimate update;
-Engineering/construction schedule; and
-Contingency analysis.
The final products of this task were developed for the project as pro-
posed in this report.
(a) Task Output
(b)
The primary outputs of Task 9 were the cost estimate summary re-
ports and construction schedules appropriate for the assessment of
feasibility of the selected Susitna project and for inclusion in
FERC licensing documentation. These documents were also prepared
to be suitable for continuous updating and/or modifications during
the subsequent study period through commencement of construction.
They are also appropriate for use in preparation of engineers•
estimates during the construction and equipment supply contract
bidding phases of the project.
Description of Work
The work undertaken in Task 9 pro vi des the basic framework for
more detailed planning, marketing, and financing of the Susitna
project to be undertaken during the period following submission of
the FERC License Application through commencement of construction.
This portion of the study was divided into two parts. During the
initial part of Task 9 activities, the information systems and
basic mechanisms necessary to develop the cost estimates and sche-
dules were established as a basis for selection of the optimum
Susitna development. The second part of Task 9 activities was de-
voted to the incorporation of more up-to-date information and ap-
propriate revisions of the estimates and schedules for feasibility
assessment of the project, prior to submission of the FERC License
Application. For ongoing cost estimating and scheduling purposes,
3-15
a continuous exchange of information was necessary with Task 2 -Sur-
veys, Task 5 -Geotechnical Exploration, Task 6 -Design Development,
Task 7 -Environmental Studies, and Task 8 -Transmission Activities.
3.11 -Task 10: Licensing
The overall basis for Task 10 and, in fact, the ultimate objective of
the entire POS, was to provide for timely preparation and assembly of
all documentation necessary for application for license to the FERC.
Should the feasibility assessment addressed in this report be accepted
by the State, the output from this task wi 11 be used as a basis for
submission of a completed application for licensing the Susitna Hydro-
electric Project.
(a) Basis of POS
As originally conceived in the February, 1980 POS, preparation of
the license would have been based on the then-current FERC regula-
tions which required submission of Exhibits A through W (less P
and Q, which were not required for licensing a major hydroelectric
project).
Assuming that technical and economic feasiblity of the project
were established and that environmental impacts and proposed miti-
gatory actions were acceptable, the major target toward which all
other work in the POS was aimed was the successful completion of a
license application to FERC. Indeed, the entire POS was prepared
in such a manner that only those tasks and subtasks considered to
be the minimum necessary for acceptance by FERC of the license
application were included in the first 30 months of effort. Al-
though it was recognized that a significant amount of follow-on
work would necessarily have to be accomplished prior to eventual
project construction, the historically lengthy periods associated
with federal processing of applications clearly suggested that the
earliest possible submission was in the best interest of the Power
Authority. It was decided entirely appropriate to file an appli-
cation which meets minimum requirements for submission, while at
the same time detailing plans for initiation or continuation of
studies whose results may be required before the license itself
was actually awarded.
(b) Revised FERC Regulations
The revision of the FERC requirements in late 1981 to five exhib-
its, A through E, did not effectively alter the scope or direction
of the study. The revised regulations altered the format rather
than the total content of the application. However, encouraging
indications of a speed-up in the FERC licensing process and a de-
sire to allow agencies additional time for constructive input to
the project planning process led to revision 3 to the POS in Feb-
ruary, 1982. In this revi sian, the scheduled date for the license
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submittal was postponed by three months to September 30, 1982.
This also allowed for incorporation of additional environmental
data into the application documents.
In accordance with FERC requirements, significant efforts have
been made by the study team to assist the Power Authority in set-
ting up a constructive Formal Agency Coordination process. This
process is designed to allow federal, state, and local agencies
the opportunity to participate in appropriate decision phases of
the study and to ensure that acceptable mitigation measures are
incorporated in the development of project designs where neces-
sary.
3.12 -Task 11: Marketing and Financing
Activities to be undertaken in this Task were aimed at examining in
some detail the potential Railbelt market for Susitna Power, the pos-
sible mechanisms through which the Power Authority might obtain ade-
quate financing for this large undertaking, and an appropriate return
on the investment. Direct state participation in the financial support
of the Susitna and other hydroelectric developments in Alaska has been
the subject of proposed and enacted state legislation over the period
of the feasibility study. This, along with the inevitable uncertainty
intrinsic to the financing of such large projects under current market
conditions, has made it somewhat difficult to determine specific finan-
cing mechanisms. The scope of this task was the subject of a major
modification under Revision 1 to the POS in September, 1980, and has
been further modified from time to time during the feasibility study.
(a) Basis of Studies
The determination of power and energy outputs from the proposed
project, the matching of this output with Railbelt demand over the
life of the project, and the cash flow requirements for construc-
tion of the project were key products of the feasibility assess-
ment which provided the basis of marketing and financing studies.
It was recognized that if the Susitna Project is selected as an
appropriate element in the growth of generating capacity in the
Railbelt region, it is likely to proceed on the basis of a partial
or complete project financing. Essential to this is a reasonably
accurate determination of revenues and properly established energy
sales agreements. Furthermore, all project risks must be identi-
fied, their potential impact assessed, and appropriate contingency
plans and provisions made.
(b) Risk Assessments
As the various elements of the project study reached the appropri-
ate level of completion, a rigorous analysis of risk was applied
as a basis for recommended contingency provisions. The approach
used involved modern techniques of analysis and probability
3-17
assessment and dealt with cost, schedule, technical, and other
controlling elements of the project.
Risks assessed included those associated with the planning, design
and construction of the project, as well as the financing of it.
There were a number of basic project. financing risks which were
addressed, including:
-Cost overruns prior to completion;
-Late completion and non-completion;
-Partial or total post-completion outages;
-Customer failure to provide anticipated cash flows;
-Regulatory risks, particularly insofar as new regulations affect
the operation (and, therefore, of course, the profitability
and/or consumer costs); and
-Technological risks, particularly insofar as the extent to which
new or relatively unproven technology may increase financing
difficulties.
(c) Financing Plans
Initial review of financing plans for the project was based on
conventional debt financing arrangements, and the level of early
year operating deficits was established. A variety of alterna-
tives have been suggested and analyzed in a continuing process of
evolving a plan which matches the policies and legislation of the
State regarding financing of hydroelectric projects. Financing
plans incorporating legislative appropriations, subordinated debt
financing, general obligation bonds, tax-exempt revenue bonds, and
other financing investments have been examined. Financial risks
were also assessed and analyzed.
3.13 -Task 12: Public Participation Program
The essential objective of the Public Participation Program was and is
to keep the public fully informed of plans, progress, and findings
associated with conduct of the detailed feasibility study. The program
also provides a means whereby the public (including individuals, public
and private organizations, and various government agencies) can influ-
ence the course of the work.
The program has been conducted effectively since commencement of the
study and outputs have included:
-Records of the proceedings of public meetings, together with written
comments and proposed action lists derived from public inputs;
-Periodic newsletters to address specific topics of public concern;
-Records of workshop meetings;
-Records of deliberations of external environmental and engineering
boards;
Written responses to i nd i vi dua 1 1 etters of inquiry addressed to the
project information office;
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-Action lists; together with notes as to status of pending actions;
-News releases;
-Audio visual recordings; and
-Displays set up with periodic update.
The management of the Public Participation Program has been undertaken
throughout the study by the Power Authority staff. Members of the
study team participated in the program as necessary by attendance at
meetings and preparation of appropriate information documents andre-
sponses to questions.
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LIST OF REFERENCES
( 1)
(2)
(3}
(4)
Acres American Incorporated, Susitna Hydroelectric Project -Plan
of Study, prepared for the, Alaska Power Authority, February
1980.
Acres American Incorporated, Susitna Hydroelectric Project -Plan
of Study·~ Revision 1, prepared for the Alaska Power Authority,
September 1980.
Acres American Incorporated, Susitna Hydroelectric Project -Plan
of Study-Revision 2, prepared for the Alaska Power Authority,
December 1981.
Acres American Incorporated, Susitna Hydroelectric Project -Plan
of Study-Revision 3, prepared for the Alaska Power Authority,
February 1982.
(5) Alaska District, U.S. Army Corps of Engineers, Plan of Study for
Hydropower Feasibility Analysis, prepared for the State of
Alaska, June 1978.
(6) Acres American Incorporated, Susitna Hydroelectric Project -Task
1 Power Studies -Subtask 1.01 Closeout Report, Review of ISER
Work, prepared for the Alaska Power Authority, December 1980.
(7} Woodward-Clyde Consultants, Forecasting Peak Electrical Demand for
Alaska•s Railbelt, prepared for Acres American Incorporated,
December 1980.
(8) Acres American Incorporated, Susitna H¥droelectric Project, Task 1
Power Studies, Termination Report, prepared for the Alaska Power
Authority, September 1980.
(9) R&M Consultants, Susitna Hydroelectric Project, Task 2 -Surveys
and Site Facilities, Access Planning Study, prepared for Acres
American Incorporated, January 1982.
(10) Woodward-Clyde Consultants, Interim Report on Seismic Studies for
Susitna Hydroelectric Project, .prepared for Acres American
Incorporated, December 1980.
(11) Woodward-Clyde Consultants, Final Report on Seismic Studies for
Susitna Hydroelectric Project, prepared for Acres American
Incorporated, February 1982.
(12) Acres Amerci an Incorporated, Susitna Hydroelectric Project, 1980
Geotechnical Report, prepared for the Alaska Power Authority,
June 1981.
LIST OF REFERENCES (Cont•d)
(13) Acres American Incorporated, Susitna Hydroelectric Project, 1980-
81 Geotechnical Report, prepared for the Alaska Power Authority,
February 1982.
(14) Acres American Incorporated, Susitna Hydroelectric Project, Devel-
opment Selection Report, prepared for the Alaska Power Author-
ity, June 1981.
(15) Acres American Incorporated, Susitna Hydroelectric Project, Tunnel
Alternative Report, prepared for the Alaska Power Authority,
July 1981.
{16) Acres American Incorporated, Susitna Hydroelectric Project, Trans-
mission Line Corridor Screening Closeout Report, prepared for
Alaska Power Authority, September 1981.
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4 ~ PREVIOUS STUDIES
In this section of the report a summary is presented of studies under~
taken by the USBR, the COE, and others over the period 1948 through
1979.
4.1 ~ Early Studies of Hydroelectric Potential
Shortly after World War II ended, the USBR conducted an initial inves~
tigation of hydroelectric potential in Alaska and issued a report of
the results in 1948. Responding to a recommendation made in 1949 by
the nineteenth Alaska territorial legislature that Alaska be included
in the Bureau of Reclamation program, the Secretary of Interior pro~
vided funds to update the 1948 work. The resulting report, issued in
1952, recognized the vast hydroelectric potential within the territory
and placed particular emphasis on the strategic location of the Susitna
River between Anchorage and Fairbanks as well as its proximity to the
connecting Railbelt (see Figures 1.1 and 4.1).
A series of studies was commissioned over the years to identify dam~
sites and conduct geotechnical investigations. By 1961, the Department
of the Interior proposed authorization of a two-dam power system in~
volving the Devil Canyon and the Denali sites (Figure 4.1). The defin~
itive 1961 report was subsequently updated by the Alaska Power
Administration (an agency of the USBR). 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 1950s and 1960s, but focused its attention on a more ambitious
development at Rampart on the Yukon River. This project was capable of
generating five times as much electric energy as Susitna annually. The
sheer size and the technological challenges associated with Rampart
captured the imagination of supporters and effectively diverted atten~
tion from the Susitna Basin for more than a decade. The Rampart report
was finally shelved in the early 1970s because of strong environmental
concerns and the uncertainty of marketing prospects for so much energy,
particularly in light of abundant natural gas which had been discovered
and developed in Cook Inlet_
The energy crisis precipitated by the OPEC oil boycott in 1973 provided
some further impetus for seeking deve 1 opment of renewable resources.
Federal funding was made available both to complete the Alaska Power
Administrationis update report on Susitna in 1974 and to launch a pre-
feasibility investigation by the COE. The State of Alaska itself com~
missioned a reassessment of the Susitna Project by the Henry J. Kaiser
Company in 1974.
Although the·gestation period for a possible Susitna Project has been
lengthy, federal, state, and private organizations have been virtually
unanimous over the years in recommending that the project proceed.
4~1
Salient features of the various reports to date are outlined in the
following sections.
4.2 -U.S. Bureau of Reclamation -1953 Study
The USBR 1952 report to the Congress on Alaska's overall hydroelectric
potential was followed shortly by the first major study of the Susitna
Basin in 1953. Ten damsites were identified above the railroad cross-
ing at Gold Creek (see also Figure 4.1):
-Gold Creek
-Olson
-Devil Canyon
Devil Creek
-Watana
-Vee
-Maclaren
-Denali
-Butte Creek
-Tyone (on the Tyone River)
Fifteen more sites were considered below Gold Creek. Howevert 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
eliminated half the original Upper Basin list, and further USBR consid-
eration centered on Olsont 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 Reclamation -1961 Study
In 1961 a more detailed feasibility study resulted in a recommended
five-stage development plan to match the load growth curve as it was
then projected. Devil Canyon was to be the first development--a 635-
foot-high arch dam with an installed capacity of about 220 MW. The
reservoir formed by the Devil Canyon dam alone would not store enough
water to permit higher capacities to be economically installed, since
long periods of relatively low flow occur in the winter months. The
second-stage would have increased storage capacity by adding an earth-
fill dam at Denali in the upper reaches of the basin. Subsequent
stages involved adding generating capacity to the Devil Canyon dam.
Geotechnical investigations at Devil Canyon were more thorough than at
Denali. At Denali, tecst pits were dug, but no drilling occurred.
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 later effort
offered a more sophisticated design, provided new cost and schedule
estimates, and addressed marketing, economics, and environmental con-
siderations.
4-2
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4.5 -Kaiser Proposal for Development
The Katser study, commissioned by the Office of the Governor in 1974,
proposed that the initial Susitna development consist of a single dam
known as High Devil Canyon (see Figure 4.1). No field investigations
were made to confirm the technical feasibility of the High Devil Canyon
location because the funding level was insufficient for such efforts.
Visual observations suggested the site was probably favorable. The
USBR had always been uneasy about foundation conditions at Denali, but
had to rely upon the Denali reservoir to provide storage during long
periods of low flow. Kaiser chose to avoid the perceived uncertainty
at Denali by proposing to build a rockfill dam at High Devil Canyon
which, at a height of 810 feet, would create a large enough reservoir
to overcome the storage problem. Although the selected sites were dif-
ferent, the COE reached a similar conclusion when it later chose the
high dam at Watana as the first to be constructed.
Subsequent developments suggested by Kaiser included a downstream dam
at the Olson site and an upstream dam at a site known as Susitna III
(see Figure 4.1). The information developed for these additional dams
was confined to estimating energy potential. As in the COE study,
future development of Denali remained a possibility if foundation con-
ditions were found to be adequate and if the value of additional firm
energy provided economic justification at some later date.
Kaiser did not regard the 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 Basin prior to the
current study was completed in 1975 by the CdE. A total of 23 alterna-
tive developments were analyzed, including those proposed by the USBR,
as well as consideration of coal as the primary energy source for Rail-
belt electrical needs. The COE agreed that an arch dam at Devil Canyon
was appropriate, but found that a high dam at the Watana site would
form a large enough reservoir for seasonal storage and would permit
continued generation during low flow periods.
The COE recommended an earthfi 11 dam at. Watana with a height of 810
feet. In the longer term, development of the Denali site remained a
possibility which, if constructed, would increase the amount of firm
energy available in dry years.
An ad hoc task force was created by Governor Jay Hammond upon comple-
tion 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 environmen-
tal and socioeconomic questions, were necessary before any construction
decision could be made.
At the federal level, concern was expressed at the Office of Management
and Budget regarding the adequacy of geotechnical data at the Watana
4-3
site as well as the validity of the economics. The apparent ambitious-
ness of the schedule and the feasibility of a thin arch dam at Devil
Canyon were also questioned. Further investigations were funded and
the COE produced an updated report in 197Y. Devil Canyon and Watana
were reaffirmed as appropriate sites, but alternative dam types were
investigated. A concrete gravity dam was analyzed as an alternative
for the thin arch dam at Devil Canyon and the Watana dam was changed
from earthfill to rockfi 11. Subsequent cost and schedule estimates
still indicated economic justification for the project.
~
TYONE" & OAMSITE
5 0 5 15
SCALE IN MILES
\ l' ' .......
' ~
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DAMS I TES PROPOSED BY OTHERS
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5 -RAILBELT LOAD FORECASTS
In this section of the report, the electrical demand forecasts for the
Railbelt region are described. Historical and projected trends are
identified and discussed, and the forecasts used in Susitna generation
planning studies are presented.
The feasibility of a major hydroelectric project depends in part upon
the extent the available capacity and energy are consistent with the
needs of the market to be served by the time the project comes on line.
Attempting to forecast future energy demand is a difficult process at
best; it is therefore particularly important that this exercise be ac-
complished in an objective manner. For this reason, the Power Author-
ity and the State of Alaska have authorized load forecasts for the
Alaska Railbelt region to be prepared independently of the feasibility
study.
5.1 -Scope of Studies
There have been two forecasts developed and used during the feasibility
study. In 1980, the Institute for Social and Economic Research (ISER)
prepared economic and accompanying end use energy demand project ions
for the Rai lbelt. The end use forecasts were further refined as part
of the feasibility study to estimate capacity demands and demand pat-
terns. Also estimated was the potential impact on these forecasts of
additional load management and energy conservation efforts. These
forecasts were used in several portions of the feasibility study, in-
cluding the development selection study, initial economic, financial
and sensitivity analyses. These forecasts are discussed in more detail
in Section 5.2.
In December, 1981, Battelle Pacific Northwest Laboratories produced a
series of revised load forecasts for the Railbelt. These forecasts
were developed as a part of the Railbelt Alternatives Study, completed
by Battelle under contract to the State of Alaska. Battelle•s fore-
casts were a result of further updating of economic projections by ISER
and some revised end-use models developed by Battelle, which took into
account price sensitivity and several other factors not included in the
1980 projections. The December 1981 Battelle forecasts were used in
this feasibility study for the final project staging, economic, finan-
cial and senstivity analyses presented in Section 18. The December
1981 Battelle forecasts are presented in Section 5.3.
5.2 -Electricity Demand Profiles
This section reviews the historical growth of electricity consumption
in the Railbelt and compares it to the national trend. Earlier fore-
casts of Railbelt electricity consumption by ISER, which were used in
Susitna deve.lopment selection studies, are also described.
5-1
(a) Historical Trends
Between 1940 and 1978, electricity sales in the Railbelt grew at
an average annual rate of 15.2 percent. This growth was roughly
twice that for the nation as a whole. Table 5.1 shows U.S. and
Alaskan annual growth rates for different periods between 1940 and
1978. The historical growth of Railbelt utility sales from 1965
is illustrated in Figure 5.1.
Although the Rail be 1t growth rates consistently exceeded the n a-
t ional average, the gap has been narrowing in 1 ater years due to
the gradual maturing of the Alaskan economy. Growth in the Rail-
belt has exceeded the national average for two reasons: popul a-
t ion growth in the Railbelt has been higher than the national
rate, and the proportion of Alaskan households served by electric
ut-ilities was lower than the U.S. average so that some growth in
the number of customers occurred independently of population
growth. Table 5.2 compares U.S. and Alaskan growth rates in the
residential and commercial sectors.
The distribution of electricity consumption between residential
and commercial-industrial-government sectors has been fairly
stable. By 1978, the commercial-industrial-government and resi-
dential sectors accounted for 52 percent and 47 percent respec-
tively. In contrast, the 1978 nationwide shares were 65 percent
and 34 percent respectively.
Historical electricity demand in the Railbelt, disaggregated by
regions, is shown in Table 5.3. During the period from 1965 to
1978, Greater Anchorage accounted for about 75 percent of kailbelt
electricity consumption followed by Greater Fairbanks with 24 per-
cent and Glennallen-Valdez with 1 percent. The pattern of region-
al sharing during this period has been quite stable and no dis-
cernible trend in regional shift has emerged. This is mainly a
result of the uniform rate of economic development in the Alaskan
Rail belt.
(b) ISER Electricity Consumption Forecasts
The methodology used by ISER to estimate electric energy sales for
the Railbelt is summarized in this section and the results ob-
tained are discussed.
(i) Methodology
The ISER e 1 ectri city demand forecasting model conceptu-
alized in computer logic the linkage between economic
growth scenarios and electricity consumption. The output
from the model is in the form of projected values of elec-
tricity consumption for each of the three geographical
areas of the Railbelt (Greater Anchorage, Greater Fairbanks
5-2
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and Glennallen-Valdez) and is classified by final use
(i.e., heating, washing, cooling, etc.) and consuming sec-
tor (commercial, residential, etc). The model produces
output on a five-year time basis from 1985 to 2010, inclu-
sive.
The ISER model consists of several submodels linked by key
variables and driven by policy and technical assumptions
and state and national trends. These submodels are grouped
into four economic models which forecast future levels of
economic activity and four electricity consumption models
which forecast the associated electricity requirements by
consuming sectors. For two of the consuming sectors it was
not possible to set up computer models and simplifying
assumptions were made.
(ii) Forecasting Uncertainty
To adequately address the uncertainty associ a ted with the
prediction of future demands, a n~nber of different econo-
mic growth scenarios were considered. These were formu-
lated by alternatively combining high, moderate and low
growth rates in the area of special projects and industry
with State government fiscal policies aimed at stimulating
either high, moderate or low growth. This resulted in a
total of nine potential growth scenarios for the state. In
addition to these scenarios, ISER also considered the po-
tential ·impact of a price reduced shift towards increased
electricity demand. A short list of six future scenarios
was selected. These concentrated around the mid-range or
11 base case .. estimate the upper and 1 ower and extremes (see
Tab 1 e 5. 4) .
(iii) Demand Forecasts
An important factor to be considered in generation planning
studies is the peak power demand associated with a forecast
of electric energy demand. The overall approach to deriva-
tion of the peak demand forecasts for the Railbelt Region
was to examine the avail able. historical data with regard to
the generation of electrical energy and to apply the ob-
served generation patterns to existing sa 1 es forecasts.
Information routinely supplied by the Railbelt utilities to
the Federal Energy Regulatory Commission was utilized to
determine these load patterns.
The first step involved an adjustment to the allocated
sales to reflect losses and energy unaccounted for. The
adjustment was made by increasing the energy allocated to
5-3
each utility by a factor computed from historical sales and
generation levels. This resulted in a gross energy genera-
tion for each utility.
The factors determined for the monthly distribution of tot-
al annual generation 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 kail-
belt system load pattern for each forecast year. Table 5.5
summarizes the total energy generation and the peak loads
for each of the low, medium, and high ISER sales forecasts,
assuming moderate government expenditure.
(iv) Adjusted ISER Forecasts
Three of the initial ISER energy forecasts were considered
in generation planning studies for development selection
studies. These included the base case (MES-GM) or medium
forecast, a low and a~ forecast. The low f~recast was
that corresponding to the low economic growth as proposed
by ISER with an adjustment for 1 ow government expenditure
(LES-GL). The high forecast corresponded to the ISER high
economic growth scenario with an adjustment for high
government expenditure (HES-GH).
The electricity forecasts summarized in Table 5.5 represent
total utility generation and include projections for self-
supplied industrial and military generation sectors. In-
cluded in these forecasts are transmission and distribution
losses in the range of 9 to 13 percent depending upon the
generation scenario assumed. These forecasts, ranging from
2.71 to 4.76 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 Railbelt supply
system. This component, which varies depending upon gener-
ation scenario, was therefore omitted from the forecasts
used for planning purposes.
The military is likely to continue purchasing energy from
the general market as long as it remains economic. How-
ever, much of their generating capacity is tied to district
heating systems which would presumably continue operation.
For study purposes, it was therefore assumed that 30 per-
cent of the estimated military generation would be supplied
from the grid system.
5-4
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The adjustments made to power and energy forecasts for use
in self-supplied industrial and military sectors are re-
flected in Table 5.6 and in Figure 5.2. The power and
energy values given in Table 5.6 are those developed by
ISER and used in the development selection studies. Annual
growth rates range from 1.99 to 5.96 percent for very low
and high forecasts with a medium generation forecast of
3.96 percent.
5.3-Battelle Load Forecasts
As part of its study of Alaska Railbelt Electric Energy Alternatives,
Battelle did extensive work in reviewing the 1980 ISER forecasts, meth-
odology, and data, and produced a new series of forecasts. These fore-
casts built on the base of information and modeling established by
ISER's 1980 work and, with the assistance of ISER, developed new models
for forecasting Railbelt economic activity and resulting electrical
energy demands. The resulting forecasts were adopted directly for use
in final generation planning studies under this feasibility study.
These revised forecasts included both an energy and peak capacity pro-
jection for each year of the study period (1982-2010). The projection
, left out port ions of electrical demand which would be self-supplied,
such as much of the military demand and some of the industrial demand.
In addition, these forecasts took into account the conservation techno-
logy and market penetration likely to take place. Details of the
Battelle forecasts and methodology are avai 1 able in a report produced
by Battelle in early 1982 (1).
The Battelle forecasts are based on energy sales, and have therefore
been adjusted by an addition of an estimated 8 percent for tr·ansmission
losses to arrive at the supply forecast to be used in generation plann-
ing. Table 5.7 presents the three Battelle forecasts which were pre-
pared to bracket the range of electrical demand for the future.
The tsattelle forecasts were used in second stage generation planning
studies. The second stage studies focused on the economic and finan-
cial feasibility of the selected Susitna project and the sensitivity of
the analyses to variation of key study assumptions. The differences
between the earlier ISER forecasts used in development selection
studies and the revised Battelle forecasts are not considered to be
significant enough to have altered the conclusions of the earlier
studies. The Railbelt generation planning studies undertaken for
Susitna feasibility assessment were based on the Battelle medium fore-
cast. The high and low Battelle forecasts were used as a basis for
sensitivity testing.
No additional information on load patterns relative to monthly and
daily shifting of load shapes was developed in the Battelle forecasts.
Thus, the historical data developed to use with the 1980 ISER forecasts
were also used with the Battelle forecasts.
5-5
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LIST OF REFERENCES
(1) Battelle Pacific Northwest Laboratories Railbelt Electric Power
Alternatives Study; Evaluation of Railbelt Electric Energy
Plans. Draft. Prepared for the Off ice of the Governor,
State of Alaska Division of Pol icy Development and Planning
and the Governor's Policy Review Committee. February.
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TABLE 5.1: HISTORICAL ANNUAL GROWTH RATES OF ELECTRIC UTILITY SALES
Anchorage and Fairbanks
Period u.s. Areas
1940 -1950 a. 8~6 20.5%
1950 -1960 8. 7~~ 15.3%
1960 -1970 7.3% 12. 9~.;
1970 -1978 4.6~· 11. 7~·
1970 -1973 6.7% 13. 1%
1973-1978 3.590 10.9%
1940 -1978 7. 3~.; 15.2%
TABLE 5.2: ANNUAL GROWTH RATES IN UTILITY CUSTOMERS AND CONSUMPTION PER CUSTOMER
Greater Anchora9e Greater Fairbanks u.s.
Customers Consumption per Customers Consumption per Customers Consumption per
(Thousands) Customer (MWh) (Thousands) Customer (MWh) (Millions) Customer (MWh)
Residential
1965 27 6.4 8.2 4.8 57.6 4.9
1978 77 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
Commercial
1965 4.0 1. 3 7.4
1978 10.2 2.9 9.1
Annual Growth
Rate (%) 7.5 6.4 1. 6
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TABLE 5.3: UTILITY SALES BY RAILBELT REGIONS
Grea£er ~ncnorage Grea£er fair6anKs Giennaiien-Vaiaez Raii6eH I o£al
1 1 1 1
Sales No. of Sales No. of Sales No. of Sales No. of
Regional Customers Regional Customers Regional Customers Customers
Year GWh Share (Thousands) GWh Share (Thousands) GWh Share (Thousands) GWh (Thousands)
1965 369 78% 31.0 98 21% 9.5 6 1 ., ,. .6 473 41.1
1966 415 32. 2 108 9.6 NA NA 523 41. 8
1967 461 34.4 66 NA NA NA 527 34.4
1968 519 39.2 141 10. 8 NA NA 661 30.0
1969 587 42.8 170 11.6 NA NA 758 54.4
1970 684 75% 46.9 213 24% 12. 6 9 1 ., ,. .8 907 60.3
1971 797 49.5 251 13. 1 10 .9 1059 63.5
1972 906 54.1 262 13.5 6 .4 1174 68.0
1973 1010 56.1 290 13.9 11 1.0 1311 71.0
1974 1086 61.8 322 15.5 14 1. 3 1422 78.6
1975 1270 75% 66.1 413 24~• 16.2 24 1% 1. 9 1707 84.2
1976 1463 71.2 423. 17. 9 33 2.2 1920 91.3
1977 1603 81.1 447 20.0 42 2.1 2092 103.2
1978 1747 79% 87.2 432 19% 20.4 38 2% 2.0 2217 109.6
Annual
Growth 12.7% 8.2% 12. 1% 6. 1 ~~ 13.9% 9. 7~~ 12. 6~• 7. B~~
NOTES:
(1) Includes residential and commercial users only, but not miscellaneous users.
Source: Federal Energy Regulatory Commission, Power System Statement.
NA: Not Available.
' )
TABLE 5.4: SUMMARY OF RAILBELT ELECTRICITY PROJECTIONS
Utilit~ Sales to All Consumin~ Sectors (GWh)
MES-GM
LES-GL 1 MES-GM
Year Bound LES-GM (Base Case)
1980 2390 2390 2390
1985 2798 2921 3171
1990 3041 3236 3599
1995 3640 3976 4601
2000 4468 5101 5730
2005 4912 5617 6742
2010 5442 6179 7952
Average Annual
Growth Rate (%)
1980-1990 2.44 3. 08 4. 18
1990-2000 3.92 4.66 4.76
2000-2010 1. 99 1. 94 3. 33
1980-2010 2.78 3. 22 4.09
NOTES:
Lower Bound = Estimates for LES-GL
Upper Bound = Estimates for HES-GH
LES = Low Economic Growth
MES = Medium Economic Growth
HES = High Economic Growth
GL = Low Government Expenditure
GM = Moderate Government Expenditure
GH = High Government Expenditure
with Price
Induced Shift
2390
3171
3599
4617
6525
8219
10142
4.18
6.13
4.51
4.94
(1) Results generated by Acres, all others by ISER.
) :\
HES-GM
2390
3561
4282
5789
7192
9177
11736
6.00
5.32
5.02
5.45
J·
J
HES-GH 1
Bound
2390
3707
4443
6317
8010
10596
14009
6.40
6.07
5.75
6.07
Military Net
Generation (GWh)
MES-GM
(Base Case)
334
334
334
334
334
334
334
o.o
0.0
0.0 o.o
LES-GM
414
414
414
414
414
414
414
o.o
0.0
0.0 o.o
Self Supplied
Industry Net Generation (GWh)
MES-GM
(Base Case)
414
571
571
571
571
571
571
3.27 o.o o.o
1. 08
MES-GM
with Price
Induced Shift
414
571
571
571
571
571
571
3. 27 o.o o.o
1. 08
1' I
HES-GM
414
847
981
981
981
981
981
9.0
0.0 o.o
2. 92
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TABLE 5.5: FORECAST TOTAL GENERATION AND PEAK LOADS -TOTAL RAILBELT REGION 1
ISEFl [ow ([tS-C~Ji! IStFl ~eaium (~ES-C~J ISEFl R1gh (RtS-C~J
Peak Peak
Generation Load Generation Load Generation
Year (GWh) (MW) (GWh) (MW) (GWh)
197B 3323 606 3323 606 3323
19BO 3522 643 3522 643 4135
19B5 4141 757 4429 BOB 552B
1990 4503 B24 4922 B98 6336
1995 5331 977 6050 1105 8013
2000 6599 1210 7327 1341 959B
2005 7188 1319 8471 1551 11B43
2010 7822 1435 9B38 1800 14730
Percent 2.71 2.73 3.45 3.46 4.76
Growth/Yr.
1978-2010
NOTES:
(1) Includes net generation from military and self-supplied industry sources.
( 2) All forecasts assume moderate government expenditure.
Peak
Load
(MW)
606
753
995
1146
1456
1750
215B
26B3
4.76
"f --~ t"---~--~ l ")
TABLE 5.6: ISEH 1980 RAILBELT REGION LOAD AND ENERGY FORECASTS U5ED FOR
GENERATION PLANNING STUDIES FOR DEVELOPMENT SELECTION
L 0 A D C A S E
Low lus oad
Management and Low Medium H.tgh
Conservation
(LES-GL)2 (MES-GM)3 (LES-GL Adjusted) 1 (HES-GH)4
Load toad Load Load
Year MW GWh Factor MW GWh factor MW GWh Factor MW GWh Factor
1980 510 2790 62.5 510 2790 62.4 510 2790 62.4 510 2790 62.4 .~>
1985 560 3090 62.8 580 3160 62.4 650 3570 62.6 695 3860 63.4
1990 620 3430 63.2 640 3505 62.4 735 4030 62.6 920 5090 63.1
1995 685 3810 63.5 795 4350 62.3 945 5170 62.) 1295 7120 62.8
2000 755 4240 63.8 950 5210 62.3 1175 6430 62.4 1670 9170 62.6
2005 835 4690 64.1 1045 5700 62.2 1380 7530 62.3 2265 12540 62.6
2010 920 5200 64.4 1140 6220 62.2 1635 8940 62.4 2900 15930 62.7
Notes:
( 1 ) LES-GL: Low economic growth/low government expenditure with load management and conservation.
(2) LES-GL: Low economic growth/low government expenditure.
(3) MES-GM: Medium economic growth/moderate government expenditure.
(4) HES-GH: High economic growth/hlgh government expenditure.
(5) Excludes reserve requirements. Energy figures are for net generation.
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TABLE ~.7: DECEMBER 1981 BATTELLE PNL RAILBELT REGION LOAD AND ENERGY
FORECASTS USED FOR GENERATION PLANNING STUDIES
Medium H1gh
load load
Year MW GWh Factor MW GWh Factor MW GWh
1981 ~74 2893 ~7.~ ~68 28~3 ~7.3 ~98 30~3
198~ 687 3431 ~7 .8 642 3234 ~7.~ 794 4231
1990 892 4456 ~7.0 802 3999 ~6.9 1098 ~703
199~ 983 4922 ~7 .1 849 4240 ~7.0 1248 6464
2000 1084 ~469 ~7.4 921 4641 ~7.4 1439 7457
200~ 1270 6428 57.8 1066 53~8 ~7.4 1769 9148
2010 1~37 7791 ~7 .9 1245 6303 ~7.8 216~ 11,43~
Average
Annual
Growth
Rate(%)
1981-1990 ~.o 4.9 3.9 3.8 7.0 7.2
1990-2000 2.0 2.1 1.4 1.~ 2.7 2.7
2001-2010 3.6 3.6 3.1 3. 1 4.2 4.4
1981-2010 3.~ 3.~ 2.7 2.8 4.~ 4.6
load
Factor
~8.3
60.8
~9.3
~9. 1
~9.0
~9.0
60.3
Note: Excludes reserve requirements. Energy figures are for net generation.
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HISTORICAL TOTAL RAILBELT UTILITY SALES
TO FINAL CUSTOMERS
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LEGEND
HES-GH : HIGH ECONOMIC GROWTH+ HIGH GOVERNMENT EXPENDITURE
MES-GM = MODERATE ECONOMIC GROWTH + MODERATE GOVERNMENT EXPENDITURE
LES-GL = LOW ECONOMIC GROWTH+ LOW GOVERNMENT EXPE~DITURE
LES-GL ADJUSTED : LOW ECONOMIC GROWTH +LOW GOVERNMENT
EXPENDITURE + LOAD MANAGEMENT AND CONSERVATION
/ , /
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ADJUSTED
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oL---------~----------~--------~----------~--------~--------~
1980 1985 1990 1995
YEAR
2000
ISER 1980 ENERGY FORECASTS .. USED
FOR DEVELOPMENT SELECTION STUDIES
2005 2010
FIGURE 5.2 •
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1980
ENERGY
1985 1990
HIGH//
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r__ ~----· --· .~
1995
YEAR
2000
/
/
2005
DECEMBER 1981 BATTELLE LOAD AND
/
2010
FOREcASTS usED FOR GENERATION PLANNING STUDIEs I ~~~[~ I
FIGURE 5.3
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6 -RAILBELT SYSTEM AND FUTURE POWER GENERATION OPTIONS
This section describes the process of assembling the information neces-
sary to carry out the systemwide generation planning studies necessary
for assessment of economic feasibility of the Susitna Project. Includ-
ed is a discussion of the existing system characteristics, the planned
Anchorage-Fairbanks intertie, and details of various generating options
including hydroelectric and thermal. Performance and cost information
required for the generation planning studies is presented for the
hydroelectric and thermal generation options considered.
Effective planning of future electric power generation sources to meet
the projected needs of the Rai lbelt Region must address a number of
concerns. Apart from the obvious goal of planning to meet projected
power and energy needs of the region, careful consideration must be
given to the trade-offs which will be required in satisfying those
needs within the constraints of technical feasibility, economic necess-
ity, acceptable environmental impacts, and social preferences. 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. The generation planning studies for the Railbelt Region which
were undertaken as part of the Susitna development selection process
were an essential first step in the study process. These studies
formed the basis for optimization of project components as well as the
economic and financial feasibility assessment for this major develop-
ment.
6.1 -Basis of Study
As with the load forecasts presented in Section 5, both a preliminary
(1980) and final (1981) generation planning analysis were completed
during the feasibility study. The initial set of data was developed in
support of the development selection studies, as described in more
detail in Section 8. These studies were completed in 1980 and re-
flected January price levels and supporting data available at that
time. Emphasis in that study was placed on currently feasible, econo-
mic generating sources. Other options, including emerging technologies
such as wind, solar, and bio-mass-fired generation were not considered.
Also not considered were commercially unavailable technologies such as
gasified coal combined cycle plants, or natural gas fue1 cells.
The information developed during the second year of the feasibility
study was used to support generation p 1 anni ng efforts which compared
alternative developments at Watana and Devil Canyon, and project de-
tails such as dam height, installed capacity, tunnel diameters, and
reservoir operating rules. The information on non-Susitna generation
6-1
options was dealt with only in sufficient detail to develop representa-
tive performance and cost data for inclusion in the non-Susitna Rail-
belt system generation scenarios.
The detailed Susitna optimization studies and economic and financial
feasibility and sensitivity assessments were based, to the maximum
extent possible, on updated information. This information was made as
consistent as possible with the Battelle Pacific Northwest Laboratories
data derived in the concurrent study of Railbelt alternatives. Infor-
mation used in Susitna generation planning studies was thus adjusted
appropriately for general consistency with Battelle data for:
-Load forecasts;
-Capital costs of alternatives;
-Fuel costs and escalation; and
-Escalation of capital costs and O&M costs.
The final generation planning studies were thus based on somewhat dif-
ferent data and assumptions relative to new generation facilities from
those used in the earlier development selection studies. However, a
great deal of data relative to the composition of the existing genera-
tion mix in the Railbelt, the status of the Intertie, and the non-Susi-
tna hydroelectric alternatives was not changed. The differences in
data values used in the final analysis compared to the development
selection studies are not considered to be large enough to have signi-
ficantly affected the conclusions of those studies. Thus, the current
Susitna feasibility assessment as presented in Section 18 is valid.
6.2-Existing System Characteristics
(a) System Description
The two major load centers of the Railbelt Region are the
Anchorage-Cook Inlet area and the Fairbanks-Tanana Valley area
(see Figure 6.1) . At present, these two areas operate i ndepen-
dently. The existing transmission system between Anchorage and
Willow consists of a network of 115 kV and 138 kV lines with
interconnection to Palmer. Fairbanks is primarily served by a
138-kV line from the 28-MW coal-fired plant at Healy. Communities
between Willow and Healy are served by local distribution.
There are currently nine electric utilities (including the Alaska
Power Administration) providing power and energy to the Railbelt
system. Table 6.1 summarizes the total generating capacity within
the Railbelt System in 1980, based on information provided by
Railbelt utilities and other sources. Table 6.2 presents the
resulting detailed listing of units currently operating in the
Railbelt, information on their performance characteristics, and
their online and OIC use assumed retirement dates. The total
Railbelt installed capacity of 984 MW as of 1980 consists of two
6-2
-I
-!
(b)
hydroelectric plants totaling 46 MW plus 938 MW of thermal genera-
tion units fired by oil, gas, or coal, as summarized in Table
6.3.
Retirement Schedule
In order to establish a retirement policy for the existing gener-
ating units, several sources were consulted, including the Power
Authority•s draft feasibility study guidelines, FERC guidelines,
Battelle•s study, and historical records. Utilities, particularly
those in the Fairbanks area, were also consulted. Based on these
sources, the following retirement periods of operation were
adopted for use in this study:
Large Coal-Fired Steam Turbines(> 100 MW):
-Small Coal-Fired Steam Turbines(< 100 MW):
-Oil-Fired Gas Turbines:
-Natural Gas-Fired Gas Turbines:
-Di ese 1 s:
-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
Six new projects are currently expected to be added to the Rail-
belt system prior to 1990. The CEA is in the process of adding
gas-fired combined-cycle capacity in Anchorage at a plant called
Beluga No.8. When complete, the total plant capacity will be 178
MW, but the plant will encompass existir;~g Units 6 and 7. Chugach
is also planning a 26.4 MW gas turbine rehabilitation at Bernice
Lake No. 4 in 1982. For study purposes, this 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 Penin-
sula. The project would include between 90 and 135 MW of in-
stalled capacity and would produce an annual average energy of 350
Gwh. For study purposes, the project is assumed to come on line
in 1988.
Three other units are also scheduled or have been added to the
system since 1980. Anchorage Municipal Light and Power Department
is adding a 90 MW gas turbine in 1982 called AMLPD No. 8. Copper
Valley Electric Association is operating the new 12 MW Solomon
Gulch Hydroelectric Project. Finally, the 7 MW Grant Lake hydro-
electric project is undergoing planning for addition to the system
in 1988 by the APA,
6-3
6.3 -Fairbanks -Anchorage Intertie
Engineering studies have been undertaken for construction of an inter-
tie between the Anchorage and Fairbanks systems. As presently envis-
aged, this connection will involve a 345-kV transmission line between
Willow and Healy scheduled for completion in 1984. The line will
initially be operated at 138 kV with the capability for expansion as
the loads grow in the load centers.
Based on these evaluations, it was concluded that an interconnected
system should be assumed for the generation planning studies, and that
the basic intertie facilities would be common to all generation scenar-
ios considered.
Costs of additional transmission facilities were added to the scenarios
as necessary for each unit added. In the 11 With Susitna11 scenarios, the
costs of adding circuits to the intertie corridor were added to the
Susitna project cost. For the non-Susitna units, transmission costs
were added as follows:
-No costs were added for combined-cycle or gas-turbine units, as they
were assumed to have sufficient siting flexibility to be placed near
the major transmission works;
A multiple coal-fired unit development in the Beluga fields was esti-
mated to have a transmission system with equal security to that
planned for Susitna, costing $220 million. This system would take
power from the bus back to the existing load center; and
A single coal-fired unit development on the Nenana area, using coal
mined in the Healy fields, would require a transmission system
costing $117 million dollars.
With the addition of a unit in the Fairbanks area in the 1990s, no
additions to the 345 kV line were considered necessary. Thus, no other
transmission changes were made to the non-Susitna plans.
6.4 -Hydroelectric Options
Numerous studies of hydroelectric potential in Alaska have been under-
taken. These date as far back as 1947, and were performed by various
agencies including the then Federal Power Commission, the COE, the
USBR, the USGS and the state of Alaska. A significant amount of the
identified potential is located in the Railbelt Region, including
several sites in the Susitna River Basin.
As discussed earlier in this section, feasibility assessment of the
selected Susitna Basin Development Plan is based on comparisons of
future Railbelt power generation scenarios with and without the Susitna
Hydroelectric Project. An obvious 11 Without Susitna 11 scenario is one
6-4
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i
which includes hydroelectric developments outside the Sustina Basin.
The plan formulation and S!=!lection methodology discussed in section 1
applied in the development of Railbelt generation plans. Those plans
which involve the Susitna Project are discussed in detail in Sections 7
and 8. Those plans which incorporCJ.te hydroelectric developments
studied during the development selection phase other than Susitna are
discussed in detail in the Development Selection Report.
The application of the five-step methodology for selection of non-Susi-
tna plg.ns which incorporate hydroelectric developments is summarit:ed in
this section, The analysis was completed in early 1981 and is based on
January 1981 cost figure and all other parameters are contained in the
Development Selection Report (l). Step 1 of this process essentially
established the overall objective of the exercise as the selection of
an optimum Ra,ilbelt generation plan which incorporated the propqsed
non-Susitna hydroelectric developments for comparison with other
plans.
Under Step 2 of the selection process, a11 feasible candidate sites
were identified for inclusion in the subsequent screening exercise. A
total of 91 potential sites were obtained from inventories of potential
sites published in the COE National Hydropower Study and the Power
AQministration report 11 Hydroelectric Alternatives for the Alaska
R a i 1 be 1 t . ''
The screening of sites under Step 3 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 selec-
tion of approximately 10 sites for consideration in plan formulation,
essentially on the basis of published data on the sites and appropri-
ately defined criteria. Figure 6.3 shows 49 of the sites which re-
mained after the two initial screens.
In Step 4 of the plan selection process~ the ten sites shortlisted
under Step 3 were further refined as a basis for formulation of Rail-
be 1 t generation plans, Engineering sketch,.. type layouts were produced
for each of the sites, and quantities and capital costs were evaluated.
These costs, listed in Table 6.4, incorporate a 20 percent allowance
for contingencies and lO percent for engineering and owner's adminis-
tration. A total of five plans were formulated incorporating various
combinations of these sites as input into the Step 5 evaluations.
Power and energy values for each of the developments were reevaluated
in Step 5 utilizing monthly streamflow and a computer reservoir simula-
tion model. The results of these calculations are summarized in Table
6.4.
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 is discussed in detail in Section 8. The criteria on
6-5
which the preferred plan was finally selected in these activities were
least present-worth cost based on economic parameters for development
selection established in Section 8.
The selected potential non-Susitna Basin hydro developments (Table 6.4)
were ranked in terms of their economic cost of energy. They were then
introduced into the all-thermal generating scenario during the planning
analyses (see Section 6.5), in groups of two or three. The most econo-
mic schemes were introduced first and were followed by the less econo-
mic schemes.
The results of these analyses, completed in early 1981, are summarized
in Table 6.5 and illustrate that a minimum total system cost can be
achieved by the introduction of the Chakachamna, Keetna, and Snow pro-
jects (See also Figure 6.4). Note that further studies of the Chaka-
chamna project were initiated in mid-1981 by Bechtel under contract to
the Power Authority. The Bechtel study is producing costs and project
concepts different from the ones presented here.
6.5 -Thermal Options -Development Selection
As discussed earlier in this section, the major portion of generating
capab·ility 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 demand in the Railbelt could be satisfied by
an all-thermal generation mix. In the following paragraphs, an outline
is presented of the studies undertaken to determine an appropriate
all-thermal generation scenario for comparison with the Susitna hydro-
electric scenario.
(a) Assessment of Thermal Alternatives
The plan formulation and selection methodology discussed in Sec-
tion 1 was adopted in a modified form to develop the necessary
all-thermal generation plans (see Figure 6.5). The overall objec-
tive established for this selection process was the selection of
an optimum all-thermal Railbelt generation plan for comparison
with other plans.
Consideration was given to gas, coal, and oil-fired generation
sources only from the standpoint of technical and economic feasi-
bility. The broader perspectives of other alternative resources
and the relevant environmental, social, and other issues involved
are being addressed in the Battelle alternatives study.
This being the case, the screening process was therefore consid-
ered unnecessary in this study, and emphasis was placed on selec-
tion of unit sizes appropriate for inclusion in the generation
planning exercise. Thus, for study purposes the following types
of thermal power generation units were considered:
6-6
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(b)
-Coal-fired steam;
-Gas-fired combined-cycle;
-Gas-fired gas turbine; and
-Diesel.
To formulate plans incorporating these alternatives it was
necessary to develop capital cost and fuel cost data for these
units and other related operational characteristics.
During the first year of this study an all-termal, without Susitna
plan, was developed. The plan was based on data for coal.,.fired
steam plans, confined cycle plants, gas~turbine platns, and diesel
power plants contained in the Development Selection Report (see
Table 6.6). The resulting all thermal plan available in early
1981 was used in the Development Selection Report for comparison
with the Susitna p 1 an avai 1 able at that time. The comparisons
were made using economic parameters over a wide range of load
forecasts, capital costs, interest (discount) rates, fuel cost and
fuel escalation rates. The result of the 1980, early 1981 studies
was the decision to continue with the Susitna feasibility study.
The following paragraphs present the thermal options used in de-
veloping the present without Susitna plan.
Coal-Fired Steam
A coal-fired steam plant is one in which steam is generated by a
coal-fired boiler and used to dri ye a steam-turbine generator.
Cooling of these units is accomplished by steam condensation in
cooling towers or by direct water cooling,
Aside from the military power plant at Fort Wainwright and the
self supplied generation at the University of Alaska, there are
currently two coal.,.fired steam plants in operation in the Railbelt
(see Table 6.1). These plants are small in comparison with new
units under consideration in the lower 48 states and in Alaska.
( i ) Capital Costs
A detailed cost study was done by Ebasco Services Incorpor~
ated as part of Battelle•s Alternative study. The report
found that it was feasible to site a plant at either the
undeveloped Beluga field or near Nenana, using Healy field
co a 1. The stlldY produced costs and operating· characteri s-
ties for both plants. All new coal units were estimated to
have an average heat rate of 10,000 BtLI/kWh and involv~ an
average construction period of five to six years. Capital
costs and operating parameters are defined for coal and
other thermal generating plants in Table 6.6.
It was found that, rather than develop solely at one field
in the non-Susitna case, development would be likely to
take place in both fields. Thus, one unit would be
developed near Nenana to service the Fairbanks load center,
with other units placed in the Beluga fields.
To satisfy the national New Performance Standards, the cap-
ital costs incorporate provision for installation of flue
gas desulfurization for-sulphur control, highly efficient
combustion technology for control of nitrogen acids, and
baghouses for particulate removal.
(ii) Fuel Costs
Fuel costs based on long-term opportunity values were set
at $1.43/MM Btu for Beluga field coal and $1.75/MM Btu for
Healy coal to be used at Nenana. Real escalation on these
values was estimated as follows:
Beluga/Coal
Healy Coal at Nenana
1982-2000
2.6%
2.3%
2001-2010
1.2%
1.1%
Det ai 1 s of the fue 1 cost information are inc 1 uded in Sec-
tion 18 of this report.
(iii) Other Performance Characteristics
Annual operation and maintenance costs and representative
forced outage rates are shown in Table 6.6.
(c) Combined Cycle
A combined cycle plant is one in which electricity is generated
partly in a gas turbine and partly in a steam turbine cycle. Com-
bined cycle plants achieve higher efficiencies than conventional
gas turbines. There are two combined cycle plants in Alaska at
present. One is operation a 1 and the other is under construction
(see Table 6.1). The plant under construction is the Beluga No. 9
unit owned by Chugach Electric Association (CEA). A 60-MW steam
turbine will be added to the system sometime in 1982.
( l) Capital Costs
A new combined cycle plant unit size of 200-MW capacity was
considered to be representative of future additions to gen-
erating capability in the Anchorage area. This is based on
economic sizing for plants in the lower 48 states and pro-
jected load increases in the Railbelt. A heat rate of
8,000 Btu/kWh was adopted based on the alternative study
completed by Battelle.
6-8
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(d)
The capital cost was estimated using the Battelle basis and
is listed in Table 6.6.
(ii) Fuel Costs
( i i i )
The combined cycle facilities would burn only gas with a
domestic market vql ue of $3.00 per MM Btu 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 one-third 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 25 percent
(1982-2000) and 2 percent (2000-2040) was used in the
analysis.
Oth~r P~rformance Characteristics
Annual operation and maintenance costs, along with a repre-
sentative forced outage rate, are given in Table 6~6.
Gas-Turbine
Gas turbines burn natural gas or oil in units similar to jet
engines which are coupled to electric generators. These also
require an appropriate water cooling arrangement.
Gas turbines are by far the main source of thermal powe1· generat-
ing resources in the Railbelt area at present. There are 470 MW
of installed gas turbines operating on natural gas in the Anchor-
age area and approximately 168 MW of oil-fired gas turbines sup-
plying the Fairbanks area (see Table 6.1). Their low initial cost,
simplicity of construction and 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-effeGtive for the Anchorage load center.
( i ) Capital C?sts
A unit size of 75 MW was considered to be representative of
a modern gas turbine plant addition in the Railbelt region.
However, the possibility of installing gas turbine units at
Beluga was not considered, since the Beluga development is
at this time primarily being considered for coal.
Gas turbine plants can be built over a two-year construc-
tion period and have an average heat rate of approximately
10,000 Btu/kWh. The capital cost were again taken from the
Battelle Alternatives study.
6-9
(i i) Fuel Costs
Gas turbine units can be operated on oil as well as natural
gas. The opportunity value and market cost for oil are
considered to be equal, at $6.50 per million Btu. The real
annual growth rates in oi 1 costs used were 2 percent for
1982-2000 and 1 percent for 2000-2040.
(iii) Other Performance Characteristics
Annual operation and maintenance costs and forced outage
rates are shown in Table 6.6.
(e) Diesel Power Generation
Most diesel plants in the Railbelt today are on standby status or
are operated only for peak load service. Nearly all the continu-
ous duty units were retired in the past several years because of
high fuel prices. About 65 MW of diesel plant capacity is cur-
rently available.
(i) Capital Costs
The high cost of diesel fuel and low capital cost makes new
diesel plants most effective for emergency use or in remote
areas where small loads exist. A unit size of 10 MW was
selected as appropriate for this type of facility. The
capital cost was derived from the same source as given in
Table 6.6.
(ii) Fuel Costs
Diesel fuel costs and growth rates are the same as oi 1
costs for gas turbines.
(iii) Other Performance Characteristics
Annual operation and maintenance and the forced outage rate
is given in Table 6.6.
(f) Plan Formulation and Evaluation
The four candidate unit types and sizes were used to formulate
plans for meeting future Railbelt power generation requirements.
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. The OGP5 generation planning model
was utilized to develop a least cost scenario incorporating the
necessary coal, oil, and gas-fired generating units.
6-10
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6.6 -Without Susitna Plan
In order to analyze the economics of developing the Susitna project, it
was necessary to analyze the costs of meeting the projected Alaska
Railbelt load forecast with and without the project. Thus, a plan
using the identified components in Section 6.5 was developed. The
basic tool used in identifying this plan was a computerized generation
planning model, Optimized Generation Planning (OGP), Version 5. The
model simulates production costs of meeting electrical demand, given
inputs of available generating resources, costs of fuel, characteris-
tics of plants, and potential new plants.
Using the system model, a base case "without Susitna" plan was struc-
tured based on middle range projections. The base case input to the
model included:
-Battelle 1 S middle range forecast from Section 5.3;
-Fuel cost as specified in Section 6.5;
-Coal-fired steam and gas-fired combined-cycle and combustion turbine
units as future additions to the system;
-Costs and characteristics of future additions as specified in Section
6.5 and Table 6.6;
-The existing system as specified in Section 6.2 and scheduled commit-
ments listed in Table 6.3;
-Middle range fuel escalation as specified in Section 6.5;
-Economic parameters of three percent interest and zero percent gener-
al inflation;
-Real escalation on operation and maintenance and capital costs at a
rate of 1.8 percent to 1992 and 2 percent thereafter; and
-Generation system re 1 i abi 1 ity set to a 1 oss of 1 oad probability of
one day in ten years. This is a probabilistic measure of the inabil-
ity of the generating system to meet projected 1 oad. One day in ten
years is a value generally accepted in the industry for planning gen-
eration systems.
The model was initially to be operated for a period from 1982-2000. It
was found that, under the medium load forecast, the critical period for
capacity addition to the system waul d be in the winter of 1992-1993.
Until that time, the existing system, given the additions of the
planned intertie and the planned units, ~ppear to be sufficient to meet
Railbelt demands. Given this information, the period of plan develop-
ment using the model was set as 1993-2010.
The following was established as the non-Susitna Railbelt base plan
(see Figure 6.6):
6-11
liiJ
(a) System as of January 1993
Coal-fired steam: 59 IVlW
Natural gas GT: 452 MW
Oi l GT: 140 MW
Diesel: 67 MW
Natural gas CC: 317 MW
Hydropower: 155 MW
Total (including committed
conditions): 1190 MW
(b) System Additions
Gas Fired
Gas Turbine Coal Fired Unit
Year ( MW) (MW)
1993 1 X 200 (Beluga Coal)
1994 1 X 200 (Beluga Coal )
1996 1 X 200 (Nenana/Healy Coal)
1997 1 X 70
1998 1 X 70
2001 1 X 70
2003 1 X 70
2004 1 X 70
2005 2 X 70
2006 1 X 70
2007 1 X 200 (Beluga Coal )
2009 1 X 70
Total 630 800
(c) System as of 2010
Coal-fired steam: 813 MW
Natural gas GT: 746 MW
Oi l GT: 0 MW
Diesel: 6 MW
Natural gas CC: 317 MW
Hydropower: 155 MW
Total (accounting for
retirements and additions) 2037 MW
The system costs attributable to this plan are discussed in Section
18.2. There is one particularly important assumption underlying the
plan. The costs associated with the Beluga development are based on
the opening of that coal field for commercial development. That devel-
opment is not a certainty now and is somewhat beyond the control of the
state, since the rights are in the hands of private interests. Even if
the seam is mined for export, there will be environmental problems to
6-12
f!'::''"
p~-
#---,
p-
('1-~
~'
Fr\
~,
fK'~.,
~'
,::··--,
-
-
r
overcome. The greatest problem will be the availability of cooling
water for the units. The prob 1 em could be solved in the "worst" case
by using the sea water from Cook Inlet as cooling water; however. this
solution would add significantly to project costs.
Two alternatives which Battelle included in their base plan which have
not been included in this plan are the Chakachamna and Allison Creek
hydroelectric plants. The Chakacharnna plant is currently the subject
of a feasibility study by the Power Authority. The current plan would
develop a 330 MW plant at a cost of $1.45 billion at January, 1982
price levels. The plant would produce nearly 1500 GWh on an average
annual basis.
Due to some current questions regarding the feas ibi 1 i ty of the Ch aka-
charnna plant, it has not been included in the non-Susitna plan. It has
been checked, however, in the sensitivity analysis presented in Section
18.
The Allison Creek hydroelectric project was included on the non"Susitna
base plan by Battelle. It has not been included in this base plan due
to its high costs, $125/MWh (1981 dollars).
The thermal plan described above has been selected as representative of
the generation scenario that would be pursued in the absence of Susit-
na. The selection has been confirmed by the Battelle results Which
show an almost identical plan to be the lowest cost of any non-Susitna
plan.
6-13
-
LIST OF REFERENCES
(1) Acres American Incorporated. Susitna Hydroelectric Project Devel-
opment Se1ettion Report. Prepared for the A1aska Power
Authority, December 1981.
-
-
,..,
-!
{
-
TABLE 6.1; TOTAL GENERATING CAPAClTY WlTHIN THE RAILBELT SY$TEM
Abbrf3viations
AMLPD
CEA
GVEA
FMUS
CVEA
MEA
HEA
SES
A PAd
u of A
TOTAL
Ra.ilbeH UUlit~
Anctmrage Municipal Light & Power
Depart!flent
Chugach Electric Association
Golden Valley Electric Association
Fairbanks Municipal Utility System
Copper Valley Electric Association
Homer Electric Association
Seward Electric Syste!fl
Alaska Power Admiqistratian
University of Alaska
(1) Installed capacity as of 1980 at 0°F
Installed Capacity
221.6
395,1
221.6
68.5
19.6
0,9
2,.6
5.5
30.0
18.6
984.0
(2,) Excludes National Defense installed capacity of 46.5 MW
Ra1lbelt Stab on
Uti lit~ Name
Anchorage Municipal AMLPD
Light & Power AMLPD
Department AMLPD
AMLPD
(AMLPD) G.M. Sullivan
Chugach Beluga
Electric Beluga
Association (CEA) Beluga
Beluga
Beluga
Beluga
Bernice Lake
International
Station
Copper Lake
Golden Valley Healy
Electric
Association North Pole
(GVEA)
Zehander
Fairbanks Chen a
Municipal
Utility
System (FMUS)
FMUS
TABLE 6.2:
Omt
No.
1
2
3
4
5,6,7
1
2
3
5
6
7
1
2
3
1
2
3
1
2
1
2
1
2
3
4
5
6
7
8
9
10
1
2
3
4
5
6
1
2
3
n
J
Dmt
T~~e
GT
GT
GT
GT
cc
GT
GT
GT
GT
GT
GT
GT
GT
GT
GT
GT
GT
HY
ST
IC
GT
GT
GT
GT
GT
GT
IC
IC
IC
IC
IC
IC
ST
ST
ST
GT
ST
GT
IC
IC
IC
GENERATING UNITS WITHIN THE RAILBELT -1980
lnstailabon Heat Rate Installed
Year (Btu/kWh) Ca~acit ~ (MW) Fuel T~~e Retirement Year
1962 14,000 16.3 NG 1992
1964 14,000 16.3 NG 1994
1968 14,000 18.0 NG 1998
1972 12,000 32.0 NG 2002
1979 8,500 139.0 NG 2011
1968 15,000 16.1 NG 1998
1968 15,000 16. 1 NG 1998
1973 10,000 53.0 NG 2003
1975 15,000 58.0 NG 2005
1976 15,000 68.0 NG 2012
1977 15,000 68.0 NG 2012
1963 23,440 8.6 NG 1993
1972 23,440 18.9 NG 2002
1978 23,440 26.4 NG 2008
1964 40,000 14.0 NG 1994
1965 --* 14.0 NG 1995
1970 --* 18.0 NG 2000
1961 --* 16.0 2011
1967 11,808 25.0 Coal 2002
1967 14,000 2.8 Oil 1997
1976 13,000 65.0 Oil 1996
1977 13,500 65.0 Oil 1997
1971 14,500 18.4 Oil 1991
1972 14,500 17.4 Oil 1992
1975 14,900 3.5 Oil 1995
1975 14,900 3.5 Oil 1995
1965 14,000 3. 5 Oil 1995
1965 14,000 3.5 Oil 1995
1965 14,000 3. 5 Oil 1995
1965 14,000 3.5 Oil 1995
1965 14,000 3. 5 Oil 1995
1965 14,000 3.5 Dil 1995
1954 14,000 5. 0 Coal 1989
1952 14,000 2.5 Coal 1987
1952 14,000 1.5 Coal 1987
1963 16,500 7.0 Oil 1993
1970 14,500 21.0 Coal 2005
1976 12,490 23.1 Oil 1997
1967 11,000 2.8 Oil 1997
1968 11,000 2.8 Oil 1998
1968 11,000 2. 8 Oil 1998
}
---} 'J ~-----, -l ,--l -1 --1 c•·------, ~--"l 1 ~· ·--1
TABLE 6.2 (Continued)
Ra1lbelt
Utility
Stahon
Name
Om£ Umt Installation Heat Rate Installed
Homer Electric
Association
(HEA)
University of
Alaska (U of A)
Copper Valley
Electric
Association (CVEA)
Matanuska Elec.
Association (MEA)
Seward Ele-ctric
System (SES)
Alaska Power
Administration
(APAd)
TOTAL
Notes:
GT = Gas turbine
CC = Combined cycle
Homer
Kenai
Pt. Graham
Seldovia
Univers.ity
University
University
University
University
CVEA
CVEA
CVEA
CVEA
CVEA
CV£A
CVEA
CVEA
Talkeetna
SES
Eklutna
HY = Conventinnal hydro
IC = Internal combustion
ST = Steam turbine
NG = Natural gas
NA = Not available
No.
1
1
1
2
3
1
2
3
1
2
1-3
4-5
6-7
1-3
4
5
6
7
1
z
3
Type Year (Btu/kWh) Capacity
IC 1979 15,000 0.9
IC 1971 15,000 0 • .2
IC 1952 15,000 0.3
lC 1964 15,000 0.6
IC 1970 15,000 0.6
ST 1980 12,000 1.5
ST 1980 12,000 1. 5
ST 1980 12,000 10.0
IC 1980 10,500 2.8
lC 1980 10.,500 2 .• 8
IC 1963 10,500 l.Z
lC 1966 10.,500 2.4
IC 1976 10,500 5.2
lC 1967 10,500 1. 8
lC 1972 10,500 1..9
IC 1975 10~:500 1.0
IC 1975 1:0,:500 2. 6
GT 1976 14,000 3.5
IC 1967 1:5, ODD 0..9
lC 1965 15,000 1. 5
IC 1965 15,000 1. 5
lC 1965 15,000 2.5
HY 19:55 30.0
984.0
*This value judged to be unrealistic for large range planning and therefore is adjusted to
15,000 for generation planning studies.
(MW)
'} ----.
Fuel Type Retirement Year
Oil 2009
Oil .2001
Oil 1982
Oil 1994
Oil 2000
Coal 2015
Coal 2015
Coal 2015
Oil 2011
Oil 2011
Oil 1993
Oil 1996
Oil 2006
Oil 1997
Oil ZOOZ
Oil zoos
Oil 2005
Oil 1996
Oil 1997
Oil 1995
Oil 1995
Oil 199:5
2005
p;;''\
TABLE 6.3: SCHEDULE OF PLANNED UTILITY ADDITIONS (19B0-19BB)
Utilit~ Unit T~ee MW Year
Avg. Energy
(GWh)
~?-:""""'\
CVEA Solomon Gulch HY 12 19B1 55
CEA Bernice Lake 114 GT 26.4 19B2
AMLPD AMLPD 1/B GT 90.0 19B2 f"il.-,.",
CEA Beluga /16,7,B cc 42* 19B2
COE Bradley Lake Hydro 90.0 19BB ~~
APA Grant Lake H~dro 7.0 198B 33
TOTAL 267.4 "'"'
* New Unit No. B will encompass Units 6 and 7, each rated
at 6B MW. Total new station capacity will be 17B MW.
70'-,
I!JP"'-.,
-!
,....
r
-
-
r-
1
r
TABLE: 6 • .4: OPERATING AND ECONdMIC PARAMETERS tOR SELECTED HYDROELECTRIC .PLANTS
Max. Average (1981 $)
Gross Installed Annual Plant Capit~l
Head Capacity En err Factor Cos~
No. Site River (ft) (MW) (Gwh uo ( $10 )
1 Snow Snow 690 50 220 50 255
2 Bruskasna Nenana: 235 30 140 53 238
3 Keetna Talkeetna 330 100 395 45 463
4 Cache Talkeetna 310 50 220 51 564
5 Browne Nenana 195 100 410 47 625
6 Talkeetna-2 Talkeetna 350 50 215 50 500
7 Hicks Matanuska 275 60 245 46 529
8 Cha:kachamna 3 Chakachatna 945 500 1925 44 1480
9 Allison Allistln Ctee k 1270 8 33 47 54
10 Strand line
Lake Beiuga 810 20 85 49 126
Notes:
(1) Including engineering and owner's administrative costs but excluding AFDC.
(2) Including IDC, Insurance, Amortization, and Operation and Maintenance Costs.
(3) An indepedent study by Bechtel has proposed an installed capacity of 330 MW,
1500 GWh annually at a cost of $1 1 405 million (1982 dollars), including AFDC.
·--~· -
Economic 2
Cost of
Energy
($/1000 Kwh)
45
113
73
100
59
90
84
30
125
115
TABLE 6,5: RESULTS OF ECONOMIC ANALYSES OF ALTERNATIVE GENERATION SCENARIOS
Installed Capac1ty (MW) by Total System total System
Cate~or~ in 2010 Installed Present Worth
Generation Scenario OGP5 Run Thermal R~dro Capacity in Cost -
~~~e l:lescn~Elon Load Forecast Id. No. Coal Gas !hi 2010 (MW) ($106)
All Thermal No Renewals Medium LME1 900 801 50 144 1895 8130
Thermal Plus No Renewals Plus: Medium L7W1 600 576 70 744 1990 7080
Alternative Chakachamna (500)1-1993
Hydro Keetna (100)-1997
No Renewals Plus: Medium LFL7 700 501 10 894 2005 7040
Chakachamna (500)-1993
Keetna (100)-1997
Snow (50)-2002
No Renewals Plus: Medium LWP7 500 576 60 822 1958 7064
Chakachamna (500)-1993
Keetna (100)-1996
Strandline (20),
Allison Creek (8),
Snow (50)-1998
No Renewals Plus: Medium LXF1 700 426 30 822 1978 7041
Chakachamna (500)-1993
Keetna (100)-1996
Strandline (20),
Allison Creek (8),
Snow (50)-2002
No Renewals Plus: Medium L403 500 576 30 922 2028 7088
Chakachamna (500)-1993
Keetna (100)-1996
Snow (50), Cache (50),
Allison Creek (8),
Talkeetna-2 (50),
Strandline (20)-2002
Notes:
( 1) Installed capacity.
'I _::I
-
-
-t
r
!
TA~L~ 6,6; SUMMARY OF THERMAL ~~~~RATING RESOURC~ PLANT PARAMETERS/19S2$
Combined Gas
C~cle Turbifle Di!'lsel
Parameter 200 MW
-·-~··-·· 200 t1W 70 MW 10 MW
Heat Rate (Btu/kWh) 10,000 s,oqo 12,200 11,500
E£~rliest AvailFJbilit}' 1989 1980 1984 19SO
0&11 Costs
Fixed O&:M ( $/}'r/kW) 16.83 7.25 2. 7 0.55
Variaple Q4M (&/MWH) 0.6 1. 69 4.8 5.38
Qutq~es
Planned Outagef:l U.;) 8 7 3.2 1
For ceq Out£Jge!:J (%) 5.7 8 8 5
Cpnstrwction Pe:rioq (~rs) 6 2
Startup Ti~T~e (}'rs) 6 4 4
Un.j_t Ca~Ha1 Cost < ~~~w) 1
Ra.j_lpelt 1 '075 627 856
~elug£! 2,061
f\!enana 2; 107
Unit ca~.j_tql Cpst ($/I<W)2
Railb13lt 2,242 1,107 636 869
Beluga
Nenana ?,309 .,.
Notes:
( 1) As estimate.d b}' ~qtt!i)lle/Eqasco )'ithout AFPC.
( 2) Inc +uding IQC ~t 0 pec.ent !'H?Cal?tion and 3 percent inter!i)st,
assuming an S-sh£!PI'ld expl'lnditure curve. ·
(3) Excludes transmission.
TABLE 6.7: 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
200
ea 1ng
Value
(Btu/lb)
7200 -8900
7500 -9400
6500 -8500
10300 -14000
~---.
~.
F-''
;r-"1,
l"'"'
MAP
LEGEND
\f PROPOSED r DAM SITES r
r
-
r-
1
----PROPOSED I~ KV LINE
-EXISTING LINES
' '
0 20 60 -----SCALE IN llll.ES
LOCATION MAP FIGURE 6.1.
SITE
SELECTION
·PREVIOUS
STUDIES
.... l ]
ENGENEERING
LAYOUTS AND
COST STUDIES
OBJECTIVE
ECONOMICS
ENVIRONMENTAL
4 ITERATIONS
SNOW ( S)
BRUSKASNA (B)
KEETNA ( K)
CACHE ( CA)
BROWNE ( BR)
TALKEETNA-2 ( T-2)
HICKS (H)
CHAKACHAMNA ( C H )
ALLISON CREEK ( AC)
STRANDLINE LAKE ( SL)
DATA ON DIFFERENT
THERMAL GENERATING
SOURCES
COMPUTER MODELS TO
EVALUATE
-POWER AND
ENERGY YIELDS
CRITERIA
ECONOMICS
-CH, K
-CH, K,S
CH,K,S 8 THERMAL
LEGEND
- C H , K , S , S L , 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
-
-
-'
-
I INCH EQUALS APPROXIMATELY 40 MILES
r /l; G 0
0-25 MW 25-IOOMW > 100 MW
I. STRANDLINE L. 13. WHISKERS 26. SNOW 39. LANE
2. LOWER BELUGA 14. COAL 27. KENAI LOWER 40. TOKICHITNA
3 • LOWER LAK€ CR. 15. CHULITNA 28. GERSTLE 41. YENTNA ...... 4. ALLISON CR. 16. OHIO 29. TANANA R. 42. CATHEDRAL BLUFFS
5. CRESCENT LAKE 2 17. LOWER CHULITNA 30. BRUSKASNA 43. JOHNSON
6. GRANT LAKE 18. CACHE 31. KANTISHNA R. 44. BROWNE
7. McCLURE BAY 19. GREENSTONE 32. UPPER BELUGA 45. JUNCTION IS.
s. UPPER NELLIE JUAN 20. TALKEETNA 2 33. COFFEE 46. VACHON IS. r 9. POWER CREEK 21. GRANITE GORGE 34. GULKANA R. 47. TAZILNA
10. SILVER LAKE 22. KEETNA 35. KLUTINA 48. KENAI LAKE
II. SOLOMON GULCH 23. SHEEP CREEK 36. BRADLEY LAKE 49. CHAKACHAMNA
12. TUSTUMENA 24. SKWENTNA 37. HICK'S SITE
25. TALACHULITNA 38. LOWE
FIGURE6.3. SELECTED ALTERNATIVE HYDROELECTRIC SITES
-
,_
~
r-
-
-
("""
r"'
r
r
I
3
3:
:'!!:
2
0
0
0
I
>-
!:::
(.)
<[ I a..
<[
(.) 715
103
0
10
8
:I:
3:6 (!)
0
0
0
>-
(!)
~4
z w
2
1980
1980
1990
LEGEND
D HYDROELECTRIC
k:t{:J COAL FIRED THERMAL
~ GAS FIRED THERMAL
2000
• OIL FIRED THERMAL( NOT SHOWN ON ENERGY DIAGRAM
NOTE: RESULTS OBTAINED FROM
OGPS RUN L FL 7
CHAKACHAMNA
EXISTING AND COMMITTED
1990 2000
TIME
1954
2010
2010
GENERATION SCENARIO INCORPORATING THERMAL . ~~~(~ I AND ALTERNATIVE HYDROPOWER DEVELOPMENTS
-MEDIUM LOAD FORECAST-FIGURE 6.4
PREVIOUS
STUDIES
UNIT TYPE
SELECTION
1
COAL: 100 MW
250 MW
500 MW
COMBINED CYCLE l 250 MW
GAS TURBINE : 75 MW
DIESEL : 10 MW
PLAN
FORMULATION
OBJECTIVE
ECONOMIC
COMPUTER MODELS
TO EVALUATE
SYSTEM WIDE ECONOMICS
EVALUATION
OBJECTIVE
GAS RENEWALS
NO GAS RENEWALS
ECONOMIC
.... J --1
NO GAS RENEWALS
LEGEND
FORMULATION OF PLANS INCORPORATING ALL-THERMAL GENERATION
STEP NUMBER IN
STANDARD PROCESS
(APPENDIX A)
FIGURE 6.5 ~
-
-
-
-I
-
-
-
-
r
-'
-I
3~----------------------------~----------------------------------------.
~ 2
0
0
Q
I
>-
1-
0
<1: a..
<1:
0
::I:
~
(!)
0
0
0
8
6
~ 4
I
>-
(!)
0:
UJ z
UJ
2
1980
1980
LEGEND
CJ
~ ~
HYDROELECTRIC
COAL FIRED THERMAL
GAS FIRED THERMAL
OIL FIRED THERMAL
1990
1990
~ .. (NOT SHOWN ON ENERGY DIAGRAM)
1591
1573
789
634
2000
TIME
2000
TIME
ALTERNATIVE GENERATION SCENARIO
BATTELLE MEDIUM LOAD FORECAST
2037
2031
968
813
2010
2010
FIGURE 6.6.
c J
!"""'
I
-i'
-
r
,....
i
7 -SUSITNA BASIN
The purpose of this section is to describe briefly the physical, bio-
logical, and socioeconomic environment of the Susitna River Basin and
vicinity, particularly in the area of the proposed development. This
section was prepared utilizing existing literature, previous studies,
and field studies conducted in 1980 and 1981, specifically for the
Susitna Hydroelectric Project.
7.1 -Climatology
The climate of the Susitna Basin is generally characterized by cold,
dry winters and warm, moderately moist summers. The upper basin above
Talkeetna is dominated by continental climatic conditions, while the
loWer basin falls within a zone of transition between maritime and con-
tinental climatic influences. This section summarizes available his-
torical climatic data for the basih and programs of field data collec-
tion and analysis undertaken during the study period.
(a) Climatic Data Records
Cl·imatic data; including temperature, precipitation, wind, cloud
cover, humdity, etc•, have been collected by the National Oceanic
and Atmospheric Administration (NOAA) at a number of stations in
the southcentral region of Alaska since 1941. Prior to the cur-"
rent studies, there were no stations located within the Upper
Susitna Basin above Talkeetna. The closest stations for which
long-term climatic data are available are located~ in relation to
the upper basin, at Talkeetna to the south and Summit to the
north. Typically, NOAA records are presented as annua 1 summaries
with comparative data for each station (see Table 7.1). Monthly
summaries are available for most of the parameters presented on a
daily basis, with selected parameters at three hour or one hour
i nterva 1 s.
Six climatic stations were established in the upper basin during
1980 to facilitate better definition and interpretation of the
available historical data. The locations of the stations were
finalized after careful evaluation of the basin characteristics,
a reconnaissance field survey to ensure a good representation of
basin climate and hydrologic characteristics, and to accommodate
the climate data requirements of the Alaska Department of Fish and
Game (ADF&G}. The stations are located near the Watana camp,
Devil Canyon damsite, Kosina Creek (ADF&G}, Tyone River near the
marshlands, at Denali, and adjacent to the Susitna Glacier. and
are shown in Figure 7.1. Each station equipment comprises a mic-
roprocessor-based continuous weather monitoring system -Weather
Wizard Model 5100; manufactured by Meteorology Research Inc. of
California. The automatic recording system was selected in pre-
ference to convent i anal mechanical recording instruments due to
ease of operation and savings in data processing costs. The data
collected at these stations include air temperature, wind speed
7-1
and direction, peak wind gust, relative humidity, precipitation,
and solar radiation. Snowfall amounts are measured in a heated
precipitation bucket at the Watana Station. Data are recorded at
30 minute intervals at the Susitna Glacier station and at 15
minute intervals at all the others. A typical monthly summary of
the data for the Watana Station is presented in Table 7.2. De-
tailed summaries of data collected at the six stations are pre-
sented in a separate report (1).
(b) Precipitation
Precipitation in the basin varies from low to moderate amounts in
the lower elevations to heavy in the mountains. Mean annual pre-
cipitation of over 80 inches is estimated to occur at elevations
about 3,000 feet in the Talkeetna Mountains and the Alaskan Range,
whereas at Talkeetna station, at Elevation 345, the average annual
precipitation recorded is about 28 inches. The average precipita-
tion lessens in a northerly direction as the continental climate
starts to predominate. At Summit station (Elevation 2397), the
average annual precipitation is only 18 inches. The seasonal dis-
tribution 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), while only 32 percent is recorded in the winter
months. Average recorded snowfall at Talkeetna is about 106
inches. Generally, snowfa 11 is restricted to the months of Octo-
ber through April, with some 82 percent snowfall recorded in the
period November to March. Typical precipitation recorded at vari-
ous NOAA stations is presented in Table 7.3.
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 Basin are generally located at elevations
below 3,000 feet; they 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 elevations. The basic
network was expanded during 1980 with the addition of three new
snow courses on the Susitna Glacier (see Figure 7.1). A program
of data collection started in the winter of 1980 and will continue
through the winter of 1981-82. Results of the snow surveys are
being published by SCS in their monthly bulletins. Selected in-
formation was used in the reevaluation of the probable maximum
flood studies (see Appendix A2).
(c) Temperature
Typical temperatures observed from historical records at the
Talkeetna and Summit stations are presented in Table 7.4. It is
expected that the temperatures at the dams ites wi 11 be somewhere
between the values observed at these stations. Typical values
observed at Watana in 1981 are shown in Table 7.2. Three hourly
7-2
-p:-;-,1
r-
1 i
r
r
-
,....
r
(d)
(e)
and monthly summaries of data recorded at the six climatic sta-
tions are presented in a separate report (1).
Evaporation
The closest stations to the Upper Susitna Basin where pan-evapora-
tion data are call ected are at the Mati'J.nuska Va 11 ey Agricultural
Experiment Station near Palmer and the University Experiment Sta-
tion in Fairbi'J.nks. The period of r13cord for each station dates
from 1944 to the present, with numerou5i gaps. Evaporation mea-
surements are restricted to the summer months~ A standard Weather
Bureau Class A plan was installed near the Watana Camp, and daily
observations were made during the summer of 1981. An estimate of
potential monthly evaporation from the proposed reservoir surfaces
was made from analysis of the historical data and mei'J.surements at
Watani'J.. Table 7.5 presents a comparative picture. Details of
this analysis are presented in Appendix A1.
Field Data Index
A Field Data Index (2) of all available climatic and hydrologic
data for the Susitna Basin was compiled in June, 1980. Updates
were made every six months to include data collected during the
period of study. The latest update (January, 1982) may be con-
sulted for a more detailed outline of available data. The Index
served the purpose of a formal transmittal of information on data
availability to study participants and agencies.
7. 2 -Hydrol osy
Historical streamflow data are available for several gaging stations on
the Susitna River p.ncj its main tributaries, .Continuous gaging records
were available for the following eight stations on the river and its
tributaries; Maclaren River near Paxson, Denali, Cantwell, Gold Creek
and Susitna stations on the Susitna River, Chulitna Station on the
Chulitna River, Talkeetna on the Talkeetna River, and Skwentna on the
Skwentna River. The longest period of record available is for the sta-
tion at Gold Creek (32 years from 1949 to 1981). At other stations.
record length varies from 6 to 23 years. Gaging was continued at all
these stations as part of the current program, and continuous stream-
flow data are available for 1980 and 1981. A gaging station was estab-
lished at the Watana damsite in 1980, and streamflow records are avail-
able for the study period~ No historical streamflow data are available
for the proposed damsites at Watana and Devil Canyon. Partial stream-
flow records are available at several other stations on the river for
varying periods; the stations are shown in Figure 7.1. For details of
available records at each station, see the Field Data Index (2).
(a) Water Resources
Above its confluence with the Chulitna River, the Susitna contri-
butes approximately 20 percent of the mean annual flow measured at
7-3
riJ
Susitna Station near Cook Inlet. Figure 7.2 shows how the mean
annual flow of the Susitna increases towards the mouth of the
river at Cook Inlet.
Seasonal variation of flow in the river is extreme and ranges 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 2,100 and 20,250 cfs respec-
tively, 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 the aver-
age, approximately 88 percent of the streamflow recorded at Gold
Creek station occurs during the summer months. At higher eleva-
tions in the basin, the distribution of flows is concentrated even
more in the summer months. For the Maclaren River near Paxson
(Elevation 4520), the average winter and summer flows are 144 and
2,100 cfs respectively, i.e. a 1 to 15 ratio. The monthly percent
of annual discharge and mean monthly discharges for the Susitna
River and tributaries at the gaging stations above the Chulitna
confluence are given in Table 7.6.
Some 40 percent of the streamflow at Gold Creek originates above
the Denali and Maclaren gages. This catchment generally comprises
the glaciers and associated high mountains. A preliminary study
of the glaciers was made to assess the effect of the glaciers on
the available streamflow for power generation. Details of this
study are presented in a separate report (3).
(b) Streamflow Extension
(c)
Acres 1 inhouse FILLIN computer program was used to fill in gaps in
historical streamflow records at the eight continuous gaging sta-
tions. The 30 year record (up to 1979) at Gold Creek was used as
the base record. The procedure adopted for fi 11 i ng in the data
gaps uses a multi-site regression technique which analyzes monthly
time-series data. Flow sequences for the 30-year period were gen-
erated at the remaining seven stations. Using these flows at
Cantwell station and observed Gold Creek flows, 30-year monthly
flow sequences at the Watana and De vi 1 Canyon dams ites were gener-
ated on the basis of prorated drainage areas. Table 7.7 shows re-
corded monthly flows at Gold Creek for the entire period of 32
years. Synthesized flows at the Watana and Devil Canyon dams ites
are presented in Tables 7.8 and 7.9. Flow duration curves based
on these monthly estimates are presented for Watana and Devil Can-
yon damsites in Figures 7.4 and 7.5. Details of the regression
analysis are presented in Appendix A1.
Low Flow Frequency Duration Analysis
A frequency analysis of run-off volumes at low flow periods rang-
ing from 1 to 10 years was carried out for recorded annual stream-
flows at Gold Creek. The lowest annual flow was observed in the
Water Year 1969 with an average flow of 5,560 cfs. The return
period of such an event is estimated at about 1 in 10,000 years
(see Figure 7.6).
7-4
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A monthly simulation of the proposed reservoirs and power devel-
opment has been carried out to estimate energy potentia 1 of the
proposed reservoirs. The critical low flow sequence for energy
generation was observed to be the 32-month period between October,
1967 and May, 1970. The sequence comprises the lowest annual flow
year described above and has a frequency of recurrence of 1 in 300
years.
The results of the analysis have been used to determine dependable
energy potential of the proposed reservoirs (see Sections 9 and
10).
(d) Floods
The most common causes of flood peaks in the Susitna River Bas·in
are snowmelt or a combination of snowmelt and rainfall over a
large area. Annual maximum peak discharges generally occur be-
tween May and October with the majority, approximately 60 percent,
occurring in June. Some of the annua 1 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. Table 7.10 presents selected flood
peaks recorded at different gaging stations.
A regional flood peak and volume frequency analysis was carried
out using the recorded floods in the Susitna River and its princi-
pal tributaries. These analyses were conducted for two different
time periods. The first period, after the ice breakup and before
freezeup (May through October), contains the largest floods which
must be accommodated by the project. The second period represents
that portion of time during which ice conditions occur in the
river (October through May). These floods, although smaller, can
be accompanied by ice jamming and must be considered during the
construction phase of the project in planning the design of cof-
ferdams for river diversion.
A set of multiple linear regression equations were developed using
physiographic basin parameters such as catchment area, stream
length, precipitation, snowfall amounts, etc., to estimate flood
peaks at ungaged sites in the basin. In conjunction with the an-
alysis of shapes and volumes of recorded large floods at Gold
Creek, a set of project design flood hydrographs of different re-
currence intervals were developed (see Figures 7.7 and 7.8).
The results of the above analysis were used for estimating flood
hydrographs at the damsites and ungaged streams and rivers along
the access road alignments for design of spillways, culverts, etc.
Table 7.11 lists mean annual, 50-, 100-, and 10,000-year floods at
the Watana and Devil Canyon damsites and at the Gold Creek gage.
Detail-s of the regional flood frequency analysis are presented in
a separate report {4).
7-5
The proposed reservoirs at Watana and Devil Canyon would be class-
ified as "large" and with "high hazard potential" according to the
guidelines for safety inspection of dams laid out by the Corps of
Engineers. This would indicate the need for the probable maximum
flood (PMF) to be considered in the evaluation of the proposed
projects. Estimates of the PMF in the Susitna River at several
locations, including the proposed damsites, were carried out by
the Corps of Engineers (COE), Alaska District, in their 1975 study
of the Susitna Basin Hydroelectric Developments. A detailed re-
view of their work by Acres suggested that the PMF estimate made
by the COE was sensitive to the three major parameters -probable
maximum precipitation, available snow pack for melting, and the
temperature sequence during the PMF event. A re-evaluation of the
PMF in the basin was, therefore, undertaken based on a more com-
prehensive climatological data base and refined basin modeling
parameters using the basin simulation program "Streamflow Synthe-
sis and Reservoir Regulation" (SSARR) used by the COE in their
study. The details of this study, including a review of the work
undertaken by the COE, are presented in Appendix A2. Estimated
peak discharges during the PMF at selected locations are included
in Table 7.11, and the PMF hydrograph is presented in Figure 7.9.
(e) River Ice
The Susitna River usually starts to freeze by late October. River
ice conditions such as thickness and strength vary according to
the river channel shape and slope and, more importantly, with
river discharge. Periodic measurements of ice thickness at sev-
eral locations in the river have been carried out during the
winters of 1961 through 1972. The maximum thicknesses observed at
selected locations on the river are given in Table 7.12. Ice
breakup in the river commences by 1 ate Apr i 1 or early May; ice
jams occasionally occur at river constrictions, resulting in rises
in the water level of up to 20 feet.
Detailed field data collection programs and studies were under-
taken to identify potential problem areas and to develop appropri-
ate mitigation measures should the Susitna project be undertaken.
The program included comprehensive aerial and ground reconnais-
sance and documentation of freezeup and break-up processes during
the 1980-81 season. These data were used to calibrate computer
models in order to predict the ice regime under post-project con-
ditions in the proposed reservoirs and in the downstream river.
Evaluations of the impacts of anticipated changes in ice condi-
tions caused by the project have been made and mitigation measures
proposed. Details of field investigation programs and the
analysis are contained in references (1) and (5).
7-6
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(f) River Morphology and Sediment Yield
(i) Available Data
Suspended sed-iment data have been collected by the USGS at
13 stations on the Susitna and its tributaries for periods
ranging from one season at small tributaries is up to 22
years at Gold Creek Station. Figure 7.1 shows location of
the stations. Generally, suspended sediment concentration,
volume of transport and particle size data is collected by
the USGS. Most of the suspended sediment is transported
during the spring/summer months June through September.
Except for a few samples collected by USGS at Denali in
1958, bed load data for the river and its tributaries are
non-existent. Data coverage during high flow-high sediment
discharge events was poor and consequently any estimate of
total annual sediment yield has a high degree of uncer-
tainty.
During the study period, several of the USGS sediment sta-
tions were revitalized and suspended sediment data col-
lected. In addition, data was collected at Cantwell and
Gold Creek Stations during specific events such as rising
and falling limbs of flood hydrographs to fill gaps in his-
torical information. During 1981, three bedload samples
were collected at four stations -Susitna River at Gold
Creek and Sunshine, Chulitna River near Talkeetna and
Talkeetna River near Talkeetna to enable better understand-
ing of river morphology below the damsites.
(ii) Estimate of Sediment Yield
Historical data and those collected during the study period
were analysed to estimate sediment yield in the river at
various locations and potential reservoirs sedimentation.
Suspended sediment rating curves have been developed for
stations on the Susitna at Gold Creek, Cantwell, Denali and
at Paxson on Maclaren River (Figure 7.10). Estimated
annual transport of suspended materials at selected gaging
stations is presented in Table 7.13. Without adequate bed-
load measurements above th~ damsites, estimates had to be
made based on earlier studies (1975) by the Corps of
Engineers and data collected at Gold Creek for potential
bedload movement into the reservoirs. Trap effi ci enci es
for the proposed reservoirs at Watana and De vi 1 Canyon were
made based on 1 iterature surveys of worldwide experience
under similar glacial river basins. Table 7.14 presents
estimated sediment deposition in the reservoirs. Details
of reservoirs sedimentation analysis may be found in (6).
7-7
(iii) Morphology of River Below Dams
Preliminary studies of the morphology of the river below
the proposed dams have been made to evaluate potential
changes caused by post-project flow regime. A detailed re-
port (7) has been prepared on the subject. The study indi-
cates that significant changes in the lower river morpho-
logy are unlikely to be caused by the projects proposed.
7.3-Regional Geology
The regional geology of the Susitna Basin area has been extensively
studied and is documented (8,9,10). The Upper Susitna Basin lies with-
in what is geologically called the Talkeetna Mountains area. This area
is geologically complex and has a history of at least three periods of
major tectonic deformation. The oldest rocks exposed in the region are
volcanic flows and limestones which were formed 250 to 300 mill ion
years before present (m.y.b .p) which are overlain by sandstones and
shales dated approximately 150 to 200 m.y.b.p. A tectonic event
approximately 135 to 180 m.y.b.p. resulted in the intrusion of large
diorite and granite plutons, which caused intense thermal metamorphism.
This was followed by marine deposition of silts and clays. The argil-
lites and phyllites which predominate at Devil Canyon were formed from
the silts and clays during faulting and folding of the Talkeetna Moun-
tains area in the Late Cretaceous period (65 to 100 m.y.b.p.). As a
result of this faulting and uplift, the eastern portion of the area was
elevated, and the oldest volcanics and sediments were thrust over the
younger metamorphics and sediments. The major area of deformation
during this period of activity was southeast of Devil Canyon and
included the Watana area. The Talkeetna Thrust Fault, a well-known
tectonic feature which has been identified in the 1 iterature, trends
northwest through this region. This fault was one of the major mechan-
isms of this overthrusting from southeast to northwest. The Devil Can-
yon area was probably deformed and subjected to tectonic stress during
the same period, but no major deformations are evident at the site
(Figure 7.ll).
The diorite pluton that forms the bedrock of the Watana site was in-
truded into sediments and volcanics about 65 m.y.b.p. The andesite and
basalt flows near the site have intruded the pluton. During the Terti-
ary period (20 to 40 m.y.b.p.) the area surrounding the sites was again
uplifted by as much as 3,000 feet. Since then, widespread erosion has
removed much of the older sedimentary and volcanic rocks. During the
last several million years, at least two alpine glaciations have carved
the Talkeetna Mountains into the ridges, peaks, and broad glacial pl a-
teaus seen today. Postglacial uplift has induced downcutting of
streams and rivers, resulting in the 500-to-700 foot deep Vshaped can-
yons that are evident today, particularly at the Vee and Devil Canyon
damsites. This erosion is believed to still be occurring and virtually
all streams and rivers in the region are considered to be actively
downcutting. This continuing erosion has removed much of the glacial
debris at higher elevations but very little alluvial deposition has
7-8
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occurred. The resulting landscape consists of barren bedrock moun-
tains, glacial till-covered plains, and exposed bedrock cliffs in can-
yons and along streams. The arctic climate has retarded development of
topsoil.
7.4-Seismicity
A two year study of seismicity of the project area was undertaken by
Woodward-Clyde Consultants (WCC) to identify faults that have the po-
tential for surface rupture within the project area and to provide est-
imates of earthquake ground motions that could be used for dam design.
Details of these studies are presented in referenced documents (1) and
(2). The results of WCCs studies are summarized in this section.
(a) Seisrnic Setting
The project lies within the Talkeetna Terrain, a part of the North
American Plate. The Terrain boundaries are denoted by the Denali-
Totschunda fault to the north and east, the Castle Mountain fault
to the south, a broad zone of deformation with volcanoes to the
west, and the Benioff Zone at depth (Figure 7 .12). With the
exception of the western boundary, which is primarily a zone of
uplift marked by Cenozoic age volcanoes, all of the boundaries are
(or contain) faults with recent displacement.
The results of the WCC study suggest that the Talkeetna Terrain is
a relatively stable tectonic unit with major strain relea~e occur-
ring along its boundaries. This conclusion is based on: the evi-
dence for recent displqcement along the Denali-Totschunda and
Castle Mountain faults and the Benioff Zone; the absence of many
major historical earthquakes within the Terrain; and the absence
of faults with recent displacement within the Terrain.
(b) Potential Earthquake Sources
The guideline used in this study to define a fault with recent
displacement was: any fault which has had surface displacement
during the past 100,000 years. Faults for which evidence of re-
cent displacement was found were evaluated during this study to
estimate their potential affect on seismic design and their poten-
tial for surface rupture within six miles of the Watana and Devil
Canyon dams ites . •
(i) Evidence of Recent Displacement
On the basis of WCCs study, the Talkeetna Terrain boundary
r-faults were identified as potential seismic sources. These
include: the Castle Mountain fault, the Denali fault, the
Benioff interplate region. and the Benioff intraplate re-
-gion (Figure 7 .12). These faults are considered to be, or
to contain, faults with recent displacement that could
7-9
cause seismic ground motions at the damsites; however,
because of their distance from the sites, these faults do
not have the potential for rupture through the sites.
A total of 13 features which were identified and ·investi-
gated in some detail near the damsite as potential seismic
sources, were found to show no evidence of recent displace-
ment. These features, therefore, were not considered to be
potential seismic sources that could cause seismic ground
motions at the sites or surface rupture through the sites.
(ii) Terrain Earthquake
Earthquakes up to a given magnitude could occur on faults
with recent displacement that might not be detectable by
the geotechnical investigations. Such earthquakes have
been designated as "Terrain earthquakes" (or 11 detection
level earthquakes" by WCC). The magnitude of the terrain
earthquake varies according to the degree of natural pre-
servation of fault-related geomorphic features and from one
tectonic environment to another. The maximum terrain
earthquake magnitude for consideration in project design
was estimated by:
-Evaluating the dimensions of surface faulting associated
with worldwide historical earthquakes in tectonic envi-
ronments similar to the Talkeetna terrain;
Identifying the threshold of surface faulting using a
group of thoroughly studied earthquakes in California;
and
-Evaluating the degree of preservation of fault-related
geomorphic features in the Talkeetna Terrain.
For this project wee estimated the terrain earthquake to be
a magnitude (Ms) 6.
(iii) Benioff Zone Earthquakes
An evaluation was made by wee of moderate to large histori-
cal earthquakes within or adjacent to the Talkeetna Ter-
rain. This study showed that all earthquake events, (ex-
cept one) 1 arger than magnitude (Ms) 5.6 in the Talkeetna
Terrain occurred on the Benioff Zone, adjacent to recog-
nized faults with recent displacement (such as the Castle
Mountain fault) or in the crust adjacent to the western
boundary of the Terrain. The earthquake near the western
boundary of the Terrain is the 1943 earthquake of magnitude
(Ms) 7.3 which had a focal depth of 11 miles (17 km) and
was located approximately 90 miles (145 km) southwest of
the Project (Figure 7 .13). Preliminary studies concluded
7-10
that this event may be associated with several 1 ineaments
in that area, therefore, not be related to any features
identified closer to the project locations.
Review of worldwide and Alaskan Benioff Zone seismicity re-
sulted in a refined configuration of the Benioff Zone. The
Benioff Zone in south-central Alaska is comprised of two
regions. In the interplate region, earthquakes occur along
the interface between the subducting Pacific Plate and the
overlying North American plate (Figure 7.12). Relatively
large earthquakes, such as the 1964 magnitude (Ms) 8.4
Prince William Sound earthquake, occur alo(lg this region.
In the intraplate region, earthquakes occur within the
subducting Pacific Plate where it is decoupled and dips
beneath the North American Plate. The maximum earthquakes
in this region of the Benioff Zone are of moderate to large
size and are smaller than the maximum earthquakes in the
interplate region.
(c) Maximum Earthquake (ME)
To establish a basis for estimating ground motions at a specific
site, and hence to design the structures to be built, estimates
were made by WCC of the maxi mum earthquakes in the region asso-
ciated with the potential earthquake sources.
The maximum earthquake (ME) was estimated for each boundary fault
(in the crust and in the Benioff Zone) and for the terrain earth-
quake. These are as follows:
Closest Approach to
Pro~osed Damsites
ME Devi 1 Canyon Watana
Source i!:U miles (km) mi 1 es (km)
Castle Mountain 7-1/2 71 (115) 65 (105)
Denali Fault 8 40 ( 64) 43 ( 70)
Benioff Zone (interplate) 8-1/2 57 ( 91) 40 ( 64)
Benioff Zone (intraplate) 7-1/2 38 ( 61) 31 ( 50)
Terrain Earthquake 6 <6 ( <10) <6 ( <10)
Work undertaken by Dr. L. Sykes of the Lamont Doherty Institute,
New York, suggests that the magnitude of the Terrain earthquake
could be as high as (Ms) 6-1/4 to 6-1/2.
(d) Reservoir Induced Seismicity (RIS)
The studies concluded that there
reservoir induced earthquake as a
such an event is not expected to
that which could occur in a given
7-11
wou 1 d be a high 1 ike 1 i hood for
result of impoundment. However,
cause an earthquake larger than
region "naturally."
(e) Ground Motion
Estimated mean peak horizontal ground accelerations and duration
of strong shaking (significant duration) at the sites due to the
governing maximum credible earthquake are the following:
Earthquake
Source
Benioff Zone
Den a 1 i Fault
Terrain Earthquake
Maxi mum
Magnitude
8-1/2
8
6
Mean Peak
Acceleration
Watana Devil Canyon
Site Site
0.35g
0.2g
0.5g
0.3g
0.2g
0.5g
Significant
Duration
(sec)
45
35
6
The probabilities of exceedance of peak ground accelerations at
the sites were estimated. The Benioff Zone was found to dominate
the contributions to the probabi 1 it i es of exceedance. Other
sources of earthquakes, including the Denali Fault and the detec-
tion level earthquake contributed only slightly to the probabili-
ties of exceedance.
These ground motions were used as a guideline in developing the
engineering design criteria set forth in Sections 9 and 10.
7.5 -Water Use and Quality
(a) Water Use
Water rights in Alaska are administered by the Alaska Department
of Natural Resources (DNR). The computer files of DNR 's water
management section were searched to determine the amount and type
of water appropriations recorded for the Susitna River and sur-
rounding area.
The mai nstem Sus i tna corri dar encamp asses 30 townships from the
proposed impoundment area downstream to the estuary. Existing
surface and ground water appropriations are primarily for single-
family and multi-family homes with approximately 50 acre feet per
year, of surface water appropriated for all purposes. On a sea-
sonal basis, the greatest usage occurs during summer months for
irrigating lawns, gardens, and crops.
There are only five areas where water appropriations are located
within one mile of the mainstem of the Susitna River (Table 7.15).
No surface water diversions are recorded that draw water directly
from the Susitna River or its adjoining side channels and
sloughs.
(b) Water Quality
The wide seasonal fluctuations in river discharge and glacial
character of the river have a significant effect on water quality.
7-12
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Suspended sediment concentrations and turbidity levels are low
during 1 ate fall and winter, but increase sharply at breakup and
remain high throughout the summer. Dissolved sol ids concentra-
tions and conductivity values are high during the low winter flow
periods and low during the high summer flows.
The Susitna River is a fast-flowing, cold-water stream of the cal-
cium bicarbonate type containing soft-to-moderately hard water
during breakup and in the summer, and moderately hard water in the
winter. Alkalinity cocentrations, with bicarbonate as the domi-
nant anion, are low to moderate during summer, and moderate to
high during winter. Nutrient concentrations, namely, nitrate and
ortho-phosphate, exist in low to moderate concentrations. Dis-
solved oxygen concentrations typically remain near the saturation
level, always exceeding 80 percent but averages near 100 percent
in the summer; in the winter saturation levels decline slightly
from the summer levels. Typically, pH values range between 7 and
8 and exhibit a wider range in the summer as compared to the win-
ter. True color, resulting from tundra runoff, displays a wider
range during summer than winter. Color levels in the vicinity of
the damsites have been measured as high as 40 color units. The
temperature remains at or near 32oF during winter, and in summer
the maximum is 55°F.
The concentrations of many trace elements monitored in the river
were low or within the range characteristic of natural waters.
However, the concentrations of some trace elements exceeded water
quality guidelines for the protection of freshwater aquatic organ-
; sms. These concentrations are the result of natural processes,
since there are no man-induced sources of these elements in the
Susitna River basin.
Concentrations of organic pesticides and herbicides, uranium, and
gross alpha radioactivity were either less than their respective
detection limits or were below levels considered to be potentially
harmful.
7.6-Fisheries Resources
Both resident and anadromous fish occur in the Susitna River system.
Resident fish species present are grayling, burbot, rainbow trout,
Dolly Varden, three spined stickleback, lognose sucker, slimy sculpin,
whitefish, and larr1preys; anadromous fish are sockeye, pink, coho, chi-
nook, chum salmon and eulachon.
(a) Anadromous Fish
Salmon utilize the Susitna River and its tributaries below Devil
Canyon as spawning habitat. Data indicate that physical barriers
prevent salmon from migrating upstream from Devil Canyon.
7-13
Salmon migration begins ·in late spring and continues into the
fall. Adult Chinook salmon enter the lower Susitna River in late
May. The confluence of the Talkeetna, Chulitna and Susitna Rivers
is thought to be a milling area for adult Chinooks. Spawning oc-
curs in the tributaries to the Susitna, particularly Indian River,
Deshka River and Willow, Clear, Peters and Portage Creeks. Spawn-
ing occurs in July and August.
Sockeye salmon enter the lower Susitna River in late spring. They
were found spawning the sloughs of the river and in McKenzie
Creek. Spawning occurs in late summer.
Pink salmon enter the lower Sus itna River every year with even-
year runs being substantially higher than odd-year runs. Peak
spawning occurs in August in sloughs and tributaries, including
Whisker, Chase, Lane, Skull, and Fourth of July Creeks.
(b) Resident Fish
Arctic grayling were found throughout the upper Susitna Basin.
Downstream from Ta 1 keetna, the spawning migration occurs in 1 ate
April. It appears these fish spawn in the tributaries in early
spring; no evidence of spawning was found between Devil Canyon and
Cook Inlet in the mainstem.
Lake trout were found only in Sully and Deadman Lake. Rainbow
trout were found at approximately the same number of habitat loca-
tions in all stretches of the river from Devil Canyon to Cook In-
let, with highest numbers occurring at habitat locations associ-
ated with tributary streams. These fish were consistently found
at Anderson and Alexander Creeks and in the Deshka River.
Burbot were found upstream of Talkeetna during the winter, with
the highest number near Curry. Downstream numbers were highest
near the mouth of the Deshka River, Alexander Creek, and four
mainstem sites.
The chum salmon migration begins during July and ends in Septem-
ber. Upstream from Talkeetna, the period from late July until the
end of August was the peak migration period. Chum salmon were
found to spawn in the mainstem of the Susitna, as well as Indian
River and Whiskers, Chase, Lane, Lower, and Skull Creeks.
The coho salmon migration runs from July into October, the 1 ast
spawn of Pacific salmon to migrate. Late July and August is the
major migrational period upstream from Talkeetna. Cohos spawn in
sloughs as well as tributaries, including Indian River, Whiskers,
Chase, Lane, and Portage Creeks.
Following deposition in the fall, the eggs hatch in the spring.
The young salmon, depending on the species and a variety of un-
known factors, either migrate to the sea within a few months or
remain in the river for one or two years before migrating down-
stream.
7-14
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Juvenile Chinook salmon often spend one winter in fresh water
before migrating to the sea. Juvenile sockeye, pink, and chums
migrate in May and June, and cohos also out migrate in the
spring.
Dolly Varden were found in the mainstem Susitna from Cook Inlet to
Devil Canyon and in Indian River and upper Portage Creek. Higher
numbers were found during July, perhaps due to higher avai1ability
of salmon eggs upon which Dolly Varden feed.
7.7-Wildlife Resources
Information presented in the big ganie section below was takeh frorn re-
ports prepared for this project by the Alaska Department of Fish arid
Game.
(a) Big Game
Species of big game which inhabit the upper Susitna basin are:
black bear, brown bear, wolverine, wolf, Dall sheep, caribou, and
moose.
( i) Bears
Black bear distribution in Alaska coincide with the pres-
ence of forest habitat. Thus, within the Susitna basin
most black bear are found in steep terrain along the river
and its tributaries~
Studies indicate approximately 55 percent of the population
is rna 1 e. The average spring age is approximately 6-1/2
years for males and 8 years for females. The population
appears to be healthy and produting. Dens utilized for
overwintering were found primarily at an elevation of 1500
to 2500. Sixteen den sites were found in the vicinity of
the proposed Dev "il Canyon impoundment (only one of which
would be flooded) and 13 in the vicinity of the proposed
Watana impoundment (9 of which would be flooded). Dens
were also found downstream of the Devil Canyon site. Bears
typically entered the dens from mid-September through mid-
October and exited from April to mid-May.
Black bears are fairly abundant in Alaska and not heavily
hunted. Within the upper Susitna basin, only an average of
eight per year are harvested, prtmarily between the Tal-
keetna and Indian Rivers. This number is below the hunter
inflicted mortal tty rate which the population could suffer
and maintain its present population level, i.e., it is be-
low the maximum sustainable yield for the population.
7-15
Brown bear occur primarily in open tundra and grassland
areas of Alaska. Aerial observations of brown bear in the
study area showed the highest percentage of sightings
occurred in shrubland areas, followed by spruce and ripar-
ian habitats. Preliminary estimates of brown bear number~
in the study area is 70 animals or one bear per 19 mi
utilizing the same figure would indicated 3 to 4 bears in
the area to be flooded. Females with cubs were not
observed frequently in the proposed impoundment area but
other bears were observed in their area, particularly
during spring.
The brown bear population of the upper Susitna basin ap-
pears to have a 50:50 sex ratio. Average spring age is ap-
proximately 7-1/2 years for both males and females. The
population is young and healthy, with litter sizes equiv-
alent to know productive bear populations in other areas.
Dens were found at elevations ranging from 2330 to 5150,
with an average elevation of 4,181 feet. (Information on
numbers of dens in area to be added, if available).
Harvest regulations for brown bears are more stringent than
for black bears. Only an average of 15 per year are taken
by hunters within the project area; this is believed to be
below the maximum substainable yield.
(ii) Wolverine
Wolverine are present in the study area and are found in
all habitat types. Their distribution appears to be re-
lated to prey availability, concentrating in hilly areas
above treeline in the summer and fall and in lower eleva-
tions during winter and early spring.
Population density is e2timated between 1 per 42 mi2 and
1 per 56 mi2 (1/56 mi ). The entire impoundment ar2a
of both Watana and Devil Canyon is approximately 80 mi ,
indicating an area inhabited by two wolverines. Utilizing
the same density figures, the entire upper Susitna basin
population is estimated at 150. Harvest data suggest the
wolverine population of the upper Susitna basin may be ex-
periencing heavier trapping mortality than the population
can sustain over a prolonged period.
(iii) Wolf
One known and five to six suspected wolf packs occur in the
area that would be most directly effected by the two reser-
voirs (Figure 7.14).
7-16
~I
~'
{ i v) -
( v)
The estimated population of these peaks combined is between
40 to 80 animals. Wolf control operations have been con-
ducted in the past, with the latest such activity occurring
in 1978.
Caribou and moose were found to be the most important prey
items to the wolves, with <:aribou representing up to 30
percent of the diet. Wolves were estimated to consume from
11 to 13 percent of the study area moose with calf mortal-
ity ranging from 16 to 17 percent. Caribou mortality from
wolf predation was estimated to vary between 2 and 13 per-
cent.
Wolves are hunted and trapped in the area. Numbers removed
annually from Game Management Unit 13 (Nelchina-Upper
Susitna) during the past 10 years ranged from 40 to 110 and
in Unit 13E, which contains the reservoir ares, 5 to 75.
Dall Sheep
Three populations of Da1l Sheep occur in the Upper Susitna
Basin: the Watana hills herd, Watana-Grebe Mountain herd
and the Portage-Tsusena Creek herd. Population 1 evel s are
not known but surveys conducted in 1980-1981 revealed 209
sheep in the Watana hills herd, 30 in the Watana-Grebe
Mountain herd and 72 in the Portage-Tsusena Creek herd, for
a total of 311. A total of 13 sheep were harvested by
sport hunters in 1980 in the Upper Susitna Basin.
A mineral lick in the Jay Creek area appears to be an im-
portant area for the Watana hi 11 s herd. Sheep were fre-
quently observed utilizing the lick, which is located at
Elevation 2200 and will be partially inundated by the
Watana reservoir.
Caribou
The Nelchina caribou herd occupies an area of approximately
20,000 square miles in Alaska. This large range can be di-
vided into 16 sub-ranges, including the Upper Susitna Basin
(Figure 7.15). Portions of the Upper Susitna Basin have
been consistently used throughout the years by 1 arge por-
tions of the herd, with most use taking place in summer,
fall, and late winter. During some years, the entire herd,
currently numbering 20,000 animals, has used the Upper
Basin. A small subherd of approximately 1,000 animals ap-
pear to be residing permanently in the upper portion of the
basin.
During the spring migration, females moved from the Lake
Louise Flat, foothills of the Alphabet hills and middle
portions of the Gakona and Chistochina Rivers.
7-17
During the spring migration, females moved from the Lake
Louise flats to the calving grounds in the eastern Tal-
keetna mountains. Migration occurred over a wide area,
with some caribou utilizing the Susitna River in the upper
area of the proposed Watana impoundment as a travel route.
A small potion of the herd appears to cross between Deadman
and Jay Creeks. None of the area utilized for calving will
be flooded.
The fall dispersal and mating period occurred as the cari-
bou moved out of the Talkeetna Mountains, across the Lake
Louise flats and into the Alphabet hills and westward.
(vi) Moose
-Upstream Moose
Moose populations upstream from the proposed impoundment
areas were studied in 1980 and 1981. The average age of
adult cow moose was higher than other Alaskan moose popu-
lation studied and pregnancy rates were lower. The phys-
ical condition of the moose appeared to be deteriorating,
yet it was not be 1 i eved the habitat was at its carrying
capacity.
Moose generally moved to lower elevations during late
spring and early summer, then back to higher elevations
in 1 ate summer and winter. The majority of moose ob-
served were in conifer and shrubland habitat.
A winter census of the impoundment area showed 28 moose
in the Devil Canyon impoundment and 42 within the Watana
impoundment. This was believed to be lower than normal
because of a mild winter. Figure 7.16 depicts moose den-
sities in the fall of 1980.
Studies of home range resulted in an estimated population
of 2,400 moose, which either seasonally or year-round
utilized an area within 5 miles of the proposed impound-
ment zones.
-Downstream Moose
Moose are also present in the Susitna River Basin down-
stream from the Devil Canyon damsite. There moose con-
sist of both resident and migratory populations. No spe-
cific calving area were located during these studies, but
it appears female use river islands to calve. During
winters of heavy snowfall, moose tend to migrate to the
river bottoms. Climax mixed birch/spruce habitat was
utilized most frequently.
7-18
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(b) Fur bearers
The major fur bearer species inhabiting the project area include
red fox, coyote, lynx, mink, pine marten, river otter, short-
tailed weasel, least weasel, muskrat and beaver. Red fox and pine
marten are the most heavily trapped of the species; coyote and
lynx are not common in the area.
Foxes were found to uti 1 i ze the shores of the Susi tna River and
deltas of tributaries during summer and autumn, and alpine zones
in the winter. All fox dens located were found above the area to
be flooded by the proposed impoundment.
Pine marten are abundant in the study area. They uti 1 i ze areas
both inside and outside the impoundment zone, including closed
forest areas and open white spruce forests.
Upstream from Gold Creek, most beaver and muskrat activity was
found on plateaus between 2,000 and 2,400 feet above the river
valley. No active beaver lodges or bank dens were found on the
Susitna River upstream from Devil Canyon or on the lower reaches
of the tributaries in this area. Furbearer activity increases
progressively downstream from De vi 1 Canyon. As the river becomes
more braided, there is a marked increase in the number of beaver
using the river, with the highest concentrations occurring south
of Montana Creek.
Short-tailed weasels are common and locally abundant in the study
area; little information is available on least weasels.
(c) Birds and Non-Game Mammals
A total of 132 species of birds were recorded in the Upper Susitna
River Basin study area. The most abundant species are common red-
poll, savannah sparrow, white crowned sparrow, lapland longspur,
and tree sparrow. Fourteen species are rare in the region but are
found in larger populations in other areas of Alaska.
Generally, the forest and woodland habitats support higher densi-
ties and/or biomass of birds than the shrub communities. Areas of
upland cliffs and block-fields and.of mat and cushion tundra have
the lowest bird usage but support species not found in other habi-
tats.
The ponds and lakes in the basin support relatively few water
birds. The most abundant waterfowl species are scaup spp., Ameri-
can wigeon, goldeneye spp., mallards, and buffleheads. Trumpeter
swans nest on a number of lakes, but none within the impoundment
zone.
Ten golden eagle, six bald eagle, and four common ravin nests are
located within the study area, while two bald eagle and four gold-
en eagle nests occur within the impoundment zone. No endangered
7-19
Iii
species (the bald eagle is not endangered in A1aska) are known to
occur in the study area.
Sixteen species of small mammals are found in the upper Susitna
Basin, the most abundant being the northern red-backed vole and
the masked shrew.
Arctic ground squirrels are abundant in well-drained tundra habi-
tats throughout the high country. Collared pika and hoary marmots
are relatively common in rock habitats above the treeline. Red
squi rre 1 s and porcupine are found in forests and woodland habi-
tats.
7.8 -Botanical Resources
The Upper Susitna River Basin is located in the Pacific Mountain phys-
iographic division in south-central Alaska. The Susitna River drains
south slops of the Alaska Range on the north slopes of the Talkeetna
Mountains on the south. Many areas along the river in the upper basin
are steep and covered with coniferous, deciduous. and mixed coniferous
and deciduous forests. Flat benches occur at the tops of these banks
and usually contain low shurb or woodland conifer communities. Low
mountains rise from these benches and are covered by sedge-grass tundra
and mat and cushion tundra.
(a) Habitat Types
The vegetation/habitat types found in the upper basin (above Gold
Creek) and floodplain downstream to Talkeetna are classified and
mapped according to the Alaska Classification System.
The major vegetation/habitat types found in the upper river drain-
age are low-mixed shrub, woodland and open blad< spruce, sedge-
grass tundra, mat and cushion tundra, and birch shrub. These veg-
etation types are typical of vast areas of interior Alaska and
northern Canada, where plants ex hi bit slow or stunted growth in
response to cold, wet, short growing seasons. Deciduous or mixed
coniferous forests which, by contrast, have more robust growth
characteristics, occupy less than 3 percent of the upper drainage
area. These types occur at lower elevations, primarily along the
Susitna River, where longer seasons of growth and better drained
soils exist; they are more comparable to vegetation/habitat types
occurring further downstream on the floodplain.
The downstream floodplain (below Devil Canyon) vegetation/habitat
consists primarily of mature and decadent cottonwood forests,
birch-spruce forest, alder thickets, and will ow-cottonwood shrub
communities. The willow cottonwood shrub and alder communities
are the earliest to establish on new gravel bars, followed by cot-
tonwood forests, and, eventually, birch-spruce forest. Wetland
areas, ponds, and lakes are present only in limited amounts within
the impoundment area.
7-20
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(b)
(c)
Table 7.16 lists the area of each habitat type present in the
Upper Susitna Basin. Of the total vegetated area of approximately
1.4 million hectares (3.5 million acres), approximately 22,160
hectares (55,400 acres) representing 1.6 percent of the vegetated
area, will be removed by the impoundments, access routes, borrow
areas, camps, and other facilities.
Floristics
A total of 246 plant species in 130 genera and 55 families were
found in the upper basin and floodplain areas. Families with the
most species are Compositae, Salicaceae, Rosaceae, Grinrineae,
Cyperaceae and Eriecaceae.
Endangered Species
No plant species occurring in Alaska are listed as endangered by
federal or state authorities. None of the species under consider-
ation for listing were found in the project area.
7.9 -Historic and Archaeological Resources
Surveys conducted located 43 archaeological sites within the area to be
affected either directly or indirectly by the Watana Dam impoundment.
These sites were found to represent human occupation dating from ap-
proximately 10,000 B.C. in the following culture periods: American
Paleoarctic, Northern Archaic Tradition, Arctic Small Tool Tradition,
Late Prehistoric Athapaskan, and Historic.
Three historic sites, all cabins built in the 1920s, occur in the
Watana impoundment area.
The Devil Canyon impoundment area includes seven archaeological sites
discovered during this study. These sites, representing various time
periods in Alaska prehistory including the American Paleoarctic and the
Northern Archaic Tradition.
One historic site, also a cabin believed to be constructed in the
1930s, lies within the Devil Canyon impoundment area.
7.10 -Socioeconomics
Three areas are discussed to depict the socioeconomic setting of the
project. These areas, discussed in Volume 2, are:
-The state of Alaska;
-The Railbelt region which includes Anchorage, Kenai-Cook Inlet,
Seward, Valdez-Chitina-Whittier, Matanuska-Susitna, southern Fair-
banks, and the Yukon-Koyukuk census divisions; and
7-21
The local region of the Matanuska-Susitna Borough and the Valdez-
Chitina-Whittier census divisions, and selected adjacent communi-
ties.
Information on the state and the Railbelt region is presented in Volume
2; information on the local area is discussed briefly below.
(a) Local
Increases in population between 1970 and 1980 in the Mat-Su
Borough (175 percent) and the Valdez-Chitina-Whittier census di-
vision (71 percent) were far higher than the state average. Popu-
lation levels stabilized as the Trans-Alaska Pipeline was com-
pleted (Figure 7.17).
The Mat-Su Borough's population rose steadily from 6,500 people in
1970 to 18,000 in 1980. Most of these people reside in the south-
ern quarter of the Borough. Palmer and Wasilla are the largest
cornmunities, with populations of approximately 2,100 and 1,550,
respectively. Wasilla experienced an extraordinary growth rate of
510 percent during the past decade. Other population centers in
the Borough are Big Lake, Eska-Sutton, Houston, and Talkeetna
(Figure 7.18).
The Valdez-Chitina-Whittier census rose from 3,100 in 1970 to ap-
proximately 13,000 during 1976 as work on the TAPS pipeline peaked
and then tapered off. The 1980 population was estimated at 6,225
(consistent demographic information is limited because of the al-
teration of this census division designation in 1980). Two trends
are notable:
-Native population has represented a significant portion of total
population {22 percent in 1970); and
Population, along with economic activity in communities along
the highways in this division, has declined since the opening of
the Parks Highway in the early 1970s and the subsequent lessen-
ing of the traffic along the Richardson Highway.
Virtually all employment in the Mat-Su Borough is government, ser-
vice, and support sector oriented. Total employment has risen
steadily from 1,145 in 1970 to 3,078 in 1979, an increase of 169
percent. However, the Borough consistently has had high unemploy-
ment rates {20 percent in 1970 and 13.8 percent in 1979), often
the highest in the state. Employment opportunities have not kept
pace with the growth of the labor force. The Borough is more de-
pendent on seasonal employment than larger population centers such
as Anchorage.
Resident civilian employment in the Valdez-Chitina-Whittier census
division also rose steadily in the 1970s from 831 in 1970 to 2,180
in 1979, an increase of 162 percent. State/local government and
7-22
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I
transportation/communications/utilities represent the largest
sources of emplo.}ment. The latter includes emplojment associated
with operation and maintenance of the petroleum pipeline. This
census division tends to have unemployment rates slightly higher
than state averages.
Nominal personal income rose substantially in the 1970s, stabiliz-
ing as the TAPS pipeline was completed. In the Mat-Su Borough,
per capita income rose from $3,957 in 1970 to $9,032 in 1977 and
declined slightly to $8,878 in 1979. In the Valdez-Chitina-
Whittier census division, the boom experience of the 1970s is even
more prominent. In 1970 the per capita personal income of $3,822
was similar to the Mat-Su Borough level; with construction of the
oil pipeline, per capita income jumped to $21,544 in 1976 and then
fell dramatically over the next few years. In 1979, per capita
income equalled $9,145.
The area of Palmer and Wasilla are suburban communities of Anchor-
age, with typical suburban 1 ifestyl es. Rural lifestyles are gen-
erally found in the more remote communities farther north. Hunt-
·ing, trapping, and fishing provide not only recreation but sea-
sonal income for a portion of the population. Partial or full
self-sufficiency is characteristic of many households, living in
an area with limited services and supplying their own heat, water
and sewage disposal. Many of the people prefer the rural life-
styles in undeveloped areas and do not wish to see rapid growth.
Others, primarily because of depressed economic conditions, hope
for increases in development and population, thereby providing
economic stimulus.
7.11-Recreational Resources
Recreational activities currently available in the Upper Susitna Basin
are those associated with undeveloped facilities. Hunting, fishing,
hiking, and camping are the primary recreational uses, along with boat-
ing on the lakes.
There are no publicly developed recreation facilities in the project
area. Private facilities include three lodges: Stephen Lake Lodge (10
structures); High Lake Lodge {9 structures); and Tsusena Lake Lodge.
Those lodges are used as bases for fishing, hunting, skiing, boating,
and hiking. Access is primarily by air.
There are no developed facilities in the impoundment areas, nor are
there any areas in the vicinity of the project that are included or
designated for inclusion in the National Wild and Scenic River System,
the National Trails System, or a federal or state wilderness area.
7.12-Aesthetic Resources
The Upper Susitna River Basin comprises a diverse landscape composite,
roadless and relatively uninhabited. The combination of these factors
creates a 1 arge region that is aesthetically renowned for its natural
7-23
beauty, where, depending upon a viewer's location in the basin, a var-
iety of visual groupings free from man-made structures are available.
Compared with other areas in Alaska, the aesthetic resources of the
project area are, typically, not seen as outstanding. Because the area
is a wilderness region positioned between the two major population cen-
ters of Fairbanks and Anchorage, the aesthetic resources of the Upper
Susitna Basin are important.
The Upper Susitna Basin offers aesthetic diversity created by the jux-
taposition of vegetation, water, and topographical features. The land-
forms of the area are defined by three major elements: the deeply in-
cised Susitna River Valley and its tributaries, the Northern Talkeetna
and Chulitna Mountains, and the Northern Talkeetna Plateau. The area's
dominating landform is the Plateau. Its features, textures and relief,
northeast trending, rounded low mountains, and highlands of generally
rolling terrain slope to meet adjacent landforms that are moderately
rugged, higher, and more mountainous. The remaining landform types
fall in the eastern project area and reflect the influence of the ad-
joining Copper River Basin. These landforms are characterized by lower
mountains and hills widely spaced on the Plateau, and flat terrain in-
terspersed with numerous ponds.
Vegetation is diverse and varies with elevation. A dense spruce-hard-
wood forest blankets the lower drainages and slopes, while vast meadows
of tundra cover higher elevations. A variety of shrubs provides the
transition between the two biomes, adding texture and color to the set-
ting. This diversity of vegetation lends itself to the natural occur-
rence of edge effect found in the more scenic visual groupings.
Color enhances the scenic composite, particularly in autumn when the
leaves of deciduous trees turn to golds and oranges, in direct contrast
to the dominating dark spruce green. Also in the autumn, the tundra
bursts into its brief bloom, adding color to the landscape.
The deeply cut canyons and gorges of the Susitna River scenically ex-
hibit the river's extraordinary power; the gorges are particularly
striking at Devil and Vee Canyons where turbulent rapids, rock outcrop-
pings and cliffs, and enclosed walls dominate the scene. The clear,
wild, and scenic mountain creeks are aesthetically stimulating; many of
them rush over and through steep rocky embankments to form waterfalls.
Lakes are numerous in the basin, ranging from small, irregularly shaped
lakes in the midst of park-like woods and mountain peaks, to a complex
of five finger-shaped lakes set in a black spruce and shrub wetland re-
gion.
Viewpoints overlooking the project and adjacent area which are found
atop the the higher mountain peaks include Deadman, Devil, and Chulitna
Buttes, the ridges above Vee Canyon, and Big Swimming Bear Lakes. On
clear days, the scenery includes extensive views of the Central Tal-
keetna Mountains and the Alaska Range, focusing upon the often spectac-
ular views of Mounts McKinley, Deborah, and Hess, and the Eldridge,
West Fork, and Susitna glaciers.
7-24
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7.13-Land Use
Existing land use in the area is typical for that of interior undevel-
oped Alaska. Broad expanses of wilderness areas are present with mini-
mal man-made developments or structures. Abandoned cabins and recrea-
tional lodges are the primary man-made structures (Figure 7.19). Sig-
nificant concentrations of residences, cabins, and other structures
occur near Portage Creek, High Lake, Gold Creek, Stephan Lake, Clarence
Lake, and Big Lake. Dog sleds and all-terrain vehicles are used as
modes of transportation into the area.
There is little land management in the area. Most land in the project
area and directly south has been selected by native corporations under
provisions of the Alaska Native Claims Settlement Act; lands to the
north are generally managed by the U.S. Bureau . of Land Management.
Figure 7.20 depicts general land use aggregation in the area.
7-25
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,_
1
LIST OF REFERENCES
1.
2.
3.
4.
5.
6.
R&M Consultants, Susitna Hydroelectric Project, Field Data Collec-
tion and Processing, prepared for Acres American Incorpor-
ated, December, 1981.
R&M Consultants, Susitna Hydroelectric Project, Field Data Index,
prepared for Acres American Incorporated, June 1980 (Revised
January 1982).
R&M Consultants, University of Alaska, Susitna Hydroelectric Pro-
ject, Glacier Studies, prepared for Acres American Incorpor-
ated, December 1981.
R&M Consultants, Susitna Hydroelectric Project, Regional Flood
Studies, prepared for Acres American Incorporated, December
1981.
Acres American Incorporated and R&M Consultants, Sus itna Hydro-
electric Project, Hydraulic and Ice Studies, prepared for
Acres American Incorporated, March 1982.
R&M Consultants, Susitna Hydroelectric Project, Reservoir Sedimen-
tation, prepared for Acres American Incorporated, January
1982.
7. R&l"l Consultants, Susitna Hydroelectric Project, River Morphology,
8.
9.
prepared for Acres American Incorporated, January 1982.
Woodward-Clyde Consultants, Interim Report on Seismic Studies for
Susitna Hydroe 1 ectri c Project, prepared for Acres American
Incorporated, December 1980.
Woodward-Clyde Consultants, F ina 1 Report on Seismic Studies for
Sus itna Hydroelectric Project, prepared for Acres American
Incorporated, February 1982.
10. Acres American Incorporated, Susitna Hydroelectric Project, 1980-
81 Geotechnical Report, prepared for the Alaska Power Author-
ity, February 1982.
l
Stittion:
1\totlth
JAN
FEB
MAR
APR
•n
JUN
JUL
AUG
SH
OCT
Vfi!AA
-r--
~1
SUMio!JT, .Al.SKA
J 26H4
Temperature "F
Averages
~ ~ ,..
i >--~ ~·~ ~ ... H ~ ·X o E :!;
9.0 -1,1!1 2.& 34
4,2 •10,4 •3,1 33
U.?. z.z 10.2 30
36.' 14,5 B,4 " "'·" z•·• ,.,, 54
60.11 40 .. 9 5!'1,8 74
62.1 43.6 H,9 76
62.111 ~1.8 52,3 78
49.fl )1,7 40.8 ,.
Temperatures "F
r----
E:~ttrernes
1 B
0
30 -26
' -28
6 •14
30 -3
2 " 27 34
ZJ 33
2 31
14 16
Normal Extremes
,-------,-----
E E ~ .~ , ,_
s )>. .§ £ H l!f 8 ::I( ~ .E g ~ il t3 ~ l_Q ~ o E :!; >---~
1•1 ., 35
J 7.9 -4·6 ).6 44 1945 H 1971
F 13., -·4 6.6 45 942 4' 1947
H 19o4 3·0 11.2 49 961 35 1971
A ,2 .. 9 14ol 2],5 57 1956 30 1944 .M .,. 7 29ol 17 .. 4 76 1960 14 1945
J 58,0 19o9 4t.o 89 ~61 H 1947
J &o.z ., .. 52.0 II 1961 J2 1970
A ,6.0 Hoi 48.6 II 968 20 19'5
s 47.1 l2•6 )9,9 15 195T 6 1956
0 10.~ 11·~ 24.0 59 1969 15 1975
N "·1 ]o7 9. 7 44 962 29 1941
D 9,2 ., .. z.9 42 969 43 1961
UN AN
·~ ~ ~~ ) ] l
TABLE 7.1: TYPICAL NOAA CLIMATE DATA RECORD
Meteorological Data For The Current Year
SUMMI.T AIRPORT St11ndard time uted: ALAS~AN Ll'llitude: 6J" 20' N longitude: 149" 01!1 ' W
---~----
Relative
PrKipit-etUJn 1n mches
·m·:-01!'grce days ---
Base 65 "F
Water equivallmt Snaw, I-ce perlf'ts 8
Resultllnt
0 0 0 'i! :I: :I: :I: :I:
c c Et c
1!' !' Ee tie 02 08 " 20 0 ~ $ . ., ~ :i ~" I g ~" I .~ t~ 0 l /?. ";!; CLoe•l time) .liE ~ 0 ,_ "<'!; 0 0 -<
c
0
-~ 0 --~
' 9 1931 0 2.17 1·1' 18-19 49.7 21.5 18•19 67 70 73 71 a 23 30
II 1975 0 loll 0.50 4 19 •• e. 1 ·-· 65 65 68 31 07 23
15 16911 0 1.65 0 .. 45 3-4 41.1 8, 7 3 75 67 35 07 17
15 1180 0 0.14 o.oe 26 ,,a 3.1 26 68 20 08 14
7 878 0 2.98 '1.90 8 •• 7 2 •• 8 69 17 24 lB
a· 420 0 0.51 0.30 30 o.o o.o 69 18 22 17
6 368 0 1.05 o.n 23 o.o o.o 81 29 23 27 I.!
29 383 0 0.96 o.zo 7 o.o o,o ~0 20 26 7
30 718 0 1.59 0.48 9 o.• 0,3 20 76 B 25 19 7,6
20 08 12
Normals, Means, And Extremes -1l!ROUGH 197sf
Pracipltation in inehes Relative Wind Normal humidity p.::;t. . c t Degree duyt ~ Base-65 8 F ~. Witter equivalent Snow, lett: ~llets @ Fru:te8t mile il , 8 8 ~ .
0 0 :;; ~ c
$ :I: :I: X :I: l 8 a
~~ §.z-• e ~~ e e 1 l!'c ~ ~g ~ .r ~" ~ E-5 -e -5 ·~ ~ ~ -5 02 08 " 20 ,~ ~-~ H ~ '!i "I
= J ~ H ~ H ~ ii H : ·s ~ • ~ li ...
;!-(loc&l time) :r ~ L ~i :I: ;z ~:eo >->-:::E.~ "-~ i5
--,-------
35 H J5 34 3~ ' 7 7 6 8 5 1 1 7
1965 0 0.91 3.J6 !948 0,09 1945 o.eo 1948 64,a l'Jltfl 16.3 !9H 68 60 69 68 l!'li.l NE 44 05 1968 '· 2 1635 0 1.23 ~.H 951 T 1950 2. 79 1951 4lt~' 1951 28,0 1964 76 75 H 76 11.9 NE 46 07 197.C. 7 .o
1668 0 1,04 4.53 946 0,07 1961 1.61 1~4, 59,) 1946 18.1 1946 76 76 70 73 u·.t NE 48 10 1971 6.2
IZH 0 0.67 :. 4.45 1966 o.o6 I9H 0,91 1963 28; 7 !970 9,1 1963 80 H 65 75 7.6 NE H 08 1971 7 ·2
856 0 o. 77. 2.66 !966 0,04 1949 0,96 1946 11.4 1959 7.5 1946 13 70 ~6 67 7",7 w 26 07 1969 7 .~
480 0 2.19 4.45 1949 o.41 1942 2.22 1967 9,4 1974 e. 7 1974 14 H 57 65 8.3 sw 29 22 1970 6,2
40] 0 J.o• ,.~a 1959 1,17 '"" 1.95 1948 9,7 !970 9,1 1970 19 78 6Z 72 1,8 sw 30 2) 1974 e,2
508 0 3,]0 6,aJ 905 o. TO 1941 z· .. to 1944 9·.o "'~ 6,0 195~ IS 81 62 76 7.4 sw H 22 19B 8.3
HJ 0 2.81 6.13 1965 0.29 1969 2.07 1944 u.~ 1958 ~~t.o 19" 85 01 59 75 7;5 NE 32 23 1971 7.4
JZ71 0 1.62 ], 79 .,2 o.u 1967 1 •. 24 196] ,.;, 1970 12.6 !970 8l 15 76 81 a.o NE 3~ 23 1970 7.6
1H9 0 1.23 4.85 952 0,06 1963 1,30 1964 ''·1 1967 21,9 1970 79 19 78 79 1(,3 NE 39 25 1970 7.1
0 1,20 4.&3 951 0,24 1945 1,09 1967 50.7 1970 27.4 1970 76 78 76 77 tz-.7 NE 44 il 1970 6,'
·UG fB FEB NOV He "AR
ElevBtion (!)round): 2197 r~t YMr: 1976
21 14
13
18 13
--
Slmri!;e 1o 'umet
--.------·~
fi ~ ; i!
0 tf-;; 0
7 7 7
13 ' 13
6 ' 17
9 6 16
' 7 18
) 9 19
2 6 22
2 7 Z2
2 6 ZJ
' ' 20
~ 5 21
7 '4 19
9 5 17
0
0
0
29 31 20
27 29 24
31 31 15
8 30 2
0 27 0
0 0 0
0
I
17
------
Meen number of d11y!
Temporatur~ .,F-~ t ~ "~ ]
c ~ -" 0 ~ Ma~~;. Min. &• ~_j lbl --~,--
~ .g ~ B :; 8'" ;i ~ -;~ ~ -0 " " ii :J -g, •• ~~ is oo ~ ~~ 1-<_Q 'b! 5..-' l:;;! ,.,_!!
zo 8 • • 34 )4 34 34
9 • 0 • 0 30 ll 20
IO ' 0 I 0 26 28 " 10 ' 0 f 0 27 31 14
7 • 0 I 0 " 30 3
7 l • I • I 22 •
12 I 2 I 3 0 2 0
16 . 2 I ' 0 • 0
18 0 • I I 0 2 0
16 2 • I • I 14 0
13 7 0 2 0 16 ]0 2
9 ' 0 I 0 27 30 13
II 6 0 I 0 30 31 19
~-
A• eragP
aHon
ssure
mb.
" pre
EleV.
lo!f'
m.s.l.
9
9
9
9
9
9
9
9
9
9
9
9
21.4 u.s
17.2
22.9
23.1
24.7
19251
R n.o u.o 25.5 89 961 •• 1971 43118 0 20.06 ~. 74 ••• T "1950 2.19 1951 '75.1 1967 Z8.o 1964 II 76 67 74 9. 7 NE •• 10 1971 7.2 68 70 227 U6 41 5 12 9 173 251 86 9 y 22 .o
(a) length of r~c:ord. years. through tht
current year unless oth@rw1se noted,
based on January d1t•.
(b) 70" and above at Alaskan stat tons.
• less than one half.
T Trace.
NORMAlS-Bas@d on record for the 19.,1-1970 period.
OAT£ OF AN EXTREME -The fiiQSt recent in cases of mu1t1JJ1e
occurrence.
PREY~Il!NG WIND DIRECTION -Rocord through 1963.
WIND DIRECTION -NIJI!\E!rals 1ndtutr. tens of deqrees clockwfse
from true north. 00 1nd1cates calm,
FAStEST MILE WlNO -Speed 15 fastest obsetved 1-mlnut~_ value
when th~ dfrectton is 1n ten5 of degrees.
NOTE: Dut:' to less than full time operation on a variable schedu1e, monuftlly recorded elements are
from broken sequences in incomplete records. Daily temperature extreme,; and precipitation
totals for portions of the record may be for other than a calcmder day. llu• period of record
for some elements is for other than consecutive years.
$ For
@ For
for
For
(or
~~!en~~~~8 {9~~~19s4° a~~6 ~~nuary
full year.
the period 1942-1953 and January
full year.
1968 to dat~ when available
196R to date when available
I Data for this station not avaJ lable for archiving nnr
publtcetion of stum~ary effective October 1976.
TABLE 7.2: MONTHLY SUMMARY FOR WATANA WEATHER STATION DATA TAKEN DURING JANUARY 1981
Res. Res. Avg. Max. Max. Day's
Max. Mln. Mean Wind Wind Wind Gust Gust Mean Mean Solar
Temp. Temp. Temp. Dir. Spd. Spd. Dir. Spd. P 'Val RH DP Precip Energy Day
~ ~ ~ ~ ~ ~ ~ ~ ~ Dir. 0' ~ MM WH/SQM '0
01 3.4 0.4 1 .9 071 5.7 5.9 085 14.6 ENE 37 -11.7 0.0 *** 01
02 2.2 -11.6 -4. 7 083 1.5 1.7 084 5.7 E 45 -15.6 o.o *** 02
03 -2.4 -13.3 -7.8 074 3.5 3.7 061 8.9 E 41 -18.3 0.0 *** 03
04 -4.3 -9.0 -6. 7 058 2.5 2.6 058 7.0 NE 49 -15.0 o.o *** 04
05 -5.8 -11.8 -8.8 074 2.2 2.4 081 5.7 E 51 -18.3 0.0 *** 05
06 -3.6 -10.9 -7.3 068 7.2 7.3 077 14.6 ENE 37 -18.0 0.0 *** 06
07 1.2 -4.8 -1.8 064 5.0 5.3 076 12.7 ENE 33 -16.0 o.o *** 07
08 -2.2 -9.4 -5. 8 072 2.3 2.4 071 7.6 ENE 45 -15.9 0.0 *** 08
09 -1.5 -6. 7 -4.1 059 5.2 5.3 077 1 2.1 ENE 30 -19.1 0.0 *** 09
10 -1.8 -9.2 -5.5 059 4.0 4.1 073 11.4 ENE 45 -14.8 0.2 *** 10
11 -1.1 -5.1 -3.1 062 4.8 4.9 075 10.8 ENE 47 -1 3. 3 0.0 *** 11
12 -1.9 -9.2 -5.6 053 2.0 2.1 071 7.6 ENE 48 -14.1 0.0 *** 12
13 -1.2 -9.9 -5.6 049 3.8 4.2 099 12.7 ENE 33 -18.3 o.o *** 13
14 3.4 -3.5 -0.0 061 5.3 5;6 075 14.0 ENE 46 -10.8 0.0 *** 14
15 3.5 -0.9 1 .3 079 3.2 4.1 081 12.7 ENE 51 -7.3 0.2 *** 15
16 o. 1 -5.7 -2. 8 050 2.9 3.2 071 12. 1 ENE 45 -13.6 o.o *** 16
17 0.9 -2.4 -0.8 060 4.2 4.4 062 12.7 ENE 35 -15.1 0.0 *** 17
18 0.9 -3.6 -1.3 068 4.8 5.0 074 14.0 ENE 35 -14.3 0.0 *** 18
19 1.3 -6.5 -2.6 109 0.4 3.9 242 1 3.3 ENE 40 -14.2 0.8 *** 19
20 -5.8 -13.6 -9.7 062 4.3 4.4 075 8.9 ENE 38 -20.3 0.0 *** 20
21 -4.8 -12.6 -8. 7 057 5.0 5.1 078 9.5 NE 35 -20.1 0.0 *** 21
22 -1.1 -5.3 -3.2 0.52 4.9 5.0 083 9.5 NE 34 -16.7 o.o *** 22
23 1.4 -5.1 -1. 9 061 4.5 4.8 083 11.4 NE 40 -13.8 o.o *** 23
24 -D. 1 -5.0 -2.6 048 3.5 4.0 055 10.2 ENE 30 -18.3 o.o *** 24
25 1.6 -3.9 -1.2 067 4.6 5.0 090 12.1 ENE 23 -19.2 0.0 *** 25
26 -4.2 -8.3 -6.3 342 0.6 1. 4 088 3.8 WSW 52 -14.3 0.2 *** 26
27 -6.2 -14.4 -10.3 062 1.0 1.2 059 3.2 ENE 51 -17.8 o.o *** 27
28 -11.3 -17.7 -14.5 065 4.5 4.6 065 14.6 ENE 44 -23.7 o.o *** 28
29 -2.2 -12.3 -7.3 058 6.2 6.4 070 13.3 NE 38 -19.7 0.0 *** 29
30 1.7 -3.2 -0.7 068 5.7 5.8 075 12.1 ENE 26 -18.3 o.o *** 30
31 -0.1 -4.2 -2.2 053 2.8 2.9 045 7.6 ENE 38 -14.7 0.2 *** 31
MONTH 3.5 -17.7 -4.5 062 3.8 4.2 08.5 14.6 ENE 40 -16.2 1. 6 ***
Gust Vel. at Max. Gust Minus 2 Intervals 13.3
Gust Vel. at Max. Gust Minus 1 Interval 12.7
Gust Vel. at Max. Gust Plus 1 Interval 12.1
Gust Vel. at Max. Gust Plus 2 Intervals 12.7
------) ~---l --'l -----'1 -----1 ,-r---~---l " ~-l --1 ·---1 ,_,. --1 -------'1 ~'-~"''"'--'') ~------. 1 •• l
TABLE 7.3: SUMMARY OF CLIMATOLOGICAL DATA
MEAN MONTHLY PRECIPITATION IN INCHES PERIOD OF
STATION JAN FEB MAR APR MAY JUNE JULY AUG SEPT OCT NOV DEC ANNUAL RECORD
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
B1g' 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 1941 -70
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 1941 -70
Gulkana 0.58 0.47 0.34 0.22 0.63 1.34 1.84 1.58 1. 72 0.88 0.75 o. 76 11 • 11 1941 -70
Matanuska Agr.
Exp. Statlon 0.79 0.63 0.52 0.62 0.75 1 .61 2.40 2.62 2.31 1.39 0.93 0.93 15.49 1951 -75
McKinley Park 0.68 0.61 0,60 0.38 0.82 2.51 3.25 2.48 1.43 0.42 0.90 0.96 15.54 1951 -75
Summit WSO 0,89 1.19 0.86 0. 72 0.60 2.18 2.97 3.09 2.56 1.57 1. 29 1 • 11 19.03 1951 -75
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 1941 -70
MEAN MONTHLY TEMPERA lURES
Anchorage 11.8 17.8 23.7 35.3 46.2 54.6 57.9 55.9 48.1 34.8 21.1 13.0 1941 -70
Big Delta -4.9 4.3 .12. 3 29.4 46_.3 57.1 59.4 54.8 43.6 25.2 6.9 -4.2 27.5 1941 -70
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 1941 -70
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 1941 -70
Matanuska Agr.
Exp. Station 9.9 17.8 23.6 36.2 46.8 54.8 57.8 55.3 47.6 33.8 20.3 12.5 34.7 1951 -75
McKinley Park -2.7 4.8 11 .5 26.4 40.8 51.5 54.2 50.2 40.8 23.0 8.9 -O.H 25.8 1951 -75
Summit WSO -0.6 5.5 9.7 23.5 37.5 48.7 52.1 48.7 39.6 23.0 9.8 3.0 25.0 1951 -75
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 1941 -70
TABLE 7.4: RECORDED AIR TEMPERATURES AT TALKEETNA AND SUMMIT IN °F
Talkeetna Summit rr-s--1
Dally 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
rro:-<. Mar 32.8 7.1 20.0 18.0 1.3 9. 7
Apr 44.0 21.2 32.6 32.5 14.4 23.5
May 56.1 33.2 44.7 45.6 29.3 37.5 ~'
June 65.7 44.3 55.0 52.4 39.8 48.7
Jul 67.5 48.2 57.9 60.2 43.4 52.1 I!"J'l''"'i
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
pt:r::J.,
Dec 18.0 -0.1 9.0 9.2 -3.3 3.0
Annual Aver age 32.8 25.0
r
r
r
-
-
Month
May
June
July
August
September
SUBTOTAL
TABLE 7.5: PAN EVAPORATION DATA
Average Monthly Plan Evaporation, Inches
Matanuska Valley
Agricultural Expansion Station
Evaporation Years Recorded
4.63 15
4.58 24
4.09 29
2.99 29
1.83 26
18.12
Univers1ty Expansion Stat1on
Evaporat1on Years Recorded
4.46 19
5.09 26
4.50 30
2.96 30
1.42 24
18.43
Watana CamR
Evaporation Yearsecorded
3.6
3.6
3.3
2.5
1.5
14.3
TABLE 7.6: AVERAGE ANNUAL AND MONTHLY FLOW AT GAGE
IN THE SUSITNA BASIN*
STATION (USGS Reference Number
Susitna River Susitna River Susitna River Maclaren Rlver
at Gold Creek Near Cantwell Near Denali Near Paxson
( 2920) (2915) (2910) (2912)
MONTH
Dralnage Area 6160 4140 950 280
sg. mi. "' Mean(cfs) "' Mean(cfs) "' Mean(cfs) "' Mean(cfs) "' ,. AI "'
JANUARY 1 '453 824 244 96
FEBRUARY 1,235 722 206 84
MARCH 1,114 692 188 76
APRIL 1,367 853 233 87
MAY 12 13,317 10 7,701 6 2,036 7 803
JUNE 24 27,928 26 19,326 22 7,285 25 2, 920
JULY 21 23,853 23 16,892 28 9,350 27 3, 181
AUGUST 19 21 ,478 20 14,658 24 8,050 22 2,573
SEPTEMBER 12 13' 171 10 7,800 10 3,350 10 1 '149
OCTOBER 5 5,639 4 3,033 3 1,122 3 409
NOVEMBER 2 2,467 2 1,449 2 490 177
DECEMBER 2 1 '773 998 314 118
ANNUAL -cfs 100 9,566 100 6,246 100 2, 739 100 973
Period of Record -Gold Creek -1950-79
Cantwell -1961-72
Denali -1957-79
Maclaren -1957-79
* Ref. USGS Streamflow Data
/~\
(":'\
)""1''1,
I{W?-c.
~,
;::(:1-,
fF,.,.--•. ,
~'
fTT"ii,
~on
~
r-,
TABLE 7.7: GOLD CREEK NATURAL FLOWS
YEAR OCT NOV DEC JAN FEB MAR , APR ~lAY JUN JUL AUG SEP AVE
1950 6335.0 2583.0 1439.0 1027.0 788.0 726.0 870.0 11510.0 19600.0 22600.0 19880.0 8301.0 7971.6
1951 3848.0 1300.0 1100.0 960.0 820.0 740.0 1617.0 14090.0 20790.0 22570.0 19670.0 21240.0 9062.1
1952 5571.0 2744.0 1900.0 1600.0 1000.0 880.0 920.0 5419.0 32370.1 26390,0 20920.0 14480.0 4'516.2
1953 8202.0 3497.0 1700.0 1100.0 820.0 820.0 1615.0 19270.0 27320.1 20200.0 20610.0 15270.0 10035.3
1954 5604.0 2100.0 1500.0 1300.0 1000.0 780.0 1235.0 17280.0 25250.0 20360.0 26100.0 12920.0 9619.1
1955 5370.0 2760.0 2045.0 1794.0 1400.0 1100.0 1200.0 9319.0 29860.0 27560.0 25750.0 14290.0 10204.0
1956 4951.0 1900.0 1300.0 980.0 970.0 940.0 950.0 17660.0 33340.0 31090.1 24530.0 18330.0 11411.8
1957 5806.0 3050.0 2142.0 1700.0 1500.0 1200.0 1200.0 13750.0 30160.0 23310.0 20540.0 19800.0 10346.5
1958 8212.0 3954.0 3264.0 1965.0 1307.0 1148.0 1533.0 12900.0 25700.0 22880.0 22540.0 7550.0 9412.8
1959 4811.0 2150.0 1513.0 1448.0 1307.0 980.0 1250.0 15990.0 23320.0 25000.0 31180.0 16920.0 10489.1
1960 6558.0 2850.0 2200.0 1845.0 1452.0 1197.0 1300.0 15780.0 15530.0 22980.0 23590.0 20510.0 9649.3
1961 7794.0 3000.0 2694.0 2452.0 1754.0 1810.0 2650.0 17360.0 29450.0 24570.0 22100.0 13370.0 10750.3
1962 5916.0 2700.0 2100.0 1900.0 1500.0 1400.0 1700.0 12590.0 43270.0 25850.0 23550.0 15890.0 115:50.5
1963 6723.0 2800.0 2000.0 1600.0 1500.0 1000.0 830.0 19030.0 26000.0 34400.0 23670.0 12320,0 10989.4
1964 6449.0 2250.0 1494.0 1048.0 966.0 713.0 . 745.0 4307.0 50580.0 22950.0 16440.0 9571.0 9792.8
1965 6291.0 2799.0 1211.0 960.0 860.0 900.0 1360.0 12990.0 25720.0 27840.0 21120.0 19350.0 10116.8
1966 7205.0 2098.0 1631.0 1400.0 1300.0 1300.0 1775.0 9645.0 32950.0 19860.0 21830.0 11750.0 9395.3
1967 4163.0 1600.0 150().0 1500.0 1400.0 1200.0 1167.0 15480.0 29510.0 26800.0 32620.0 16870.0 11150.8
1968 4900.0 2353.0 2055.0 1981.0 1900.0 1900.0 1910.0 16180.0 31550.0 26420.0 17170.0 8816.0 9761.3
1969 3822.0 1630.0 882.0 724.0 723.0 816.0 1510.0 11050~0 15500.0 16100.0 8879,0 5093.0 5560.8
1970 •3124.0 1215.0 866.0 824.0 768.0 776.0 1080.0 11380.0 18630,0 22660.0 19980.0 9121.0 7535.3
1971 5288.0 3407.0 2290.0 1442.0 1036.0 950.0 1082.0 3745.0 32930.0 23950.0 31910.0 14440.0 10205.8
1972 5847.0 3093.0 2510.0 2239.0 2028.0 1823.0 1710.0 21890.0 34430.0 22770.0 19290.0 12400.0 10835.8
1973 4826.0 2253.0 1465.0 1200.0 1200.0 1000.0 1027.0 8235.0 27800,0 18250.0 20290.0 9074.0 8051.7
1974 3733.0 1523.0 1034.0 874.0 777.0 724.0 992.0 16180.0 17870.0 18800.0 16220.0 12250.0 7581.4
1975 3739.0 1700.0 1603.0 1516.0 1471.0 1400.0 1593.0 15350.0 32310.0 27720.0 18090.0 16310.0 10233.5
1976 7739.0 1993.0 1081.0 974.0 950,0 900.0 1373.0 12620.0 24380.0 18940.0 19800.0 6881.0 8135.9
1977 3874.0 2650.0 2403.0 1629.0 1618.0 1500.0 1680.0 12680.0 37970.0 22870.0 19240.0 12640.0 10079.5
1978 7571.0 3525.0 2589.0 2029.0 1668.0 1605.0 1702.0 11950.0 19050.0 21020.0.16390.0 8607.0 8142.2
1979 4907.0 2535.0 1681.0 1397.0 1286.0 1200.0 1450.0 13870.0 24690.0 28880.1 20460.0 10770.0 9427.2
1980 7311.0 4192.0 2416.0.., 1748.0 1466.0~ 1400.0. 1670.gw12060.~29080.0 32660.0 20960.0 13280.0. 10686.9
1981 7725.0 3986.0 1773.1 1453.6. 1235.6 1114.3 1367. 13316. 18143.0 32000.0 38538.0 13171.1 11152.0
AVE 5756·7 2568.4 1793.2 1462.8 1242.8 1123.2 1377.0 13277.4 27657.9 24382.8 21995.5 13174.5 9651.0
*Long term average flows assumed
TABLE 7.8: WATANA ESTIMATED NATURAL FLOWS
YEAR OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEF'
1950 4719.91. 2083.6 1168.9 815.1 641.7 569.1 680.1 8655.9 16432.1 19193.4 16913.6 7320.4
1951 3299.1 1107.3 906.2 ao8.o 673.0 619.8 1302.2 11649.8 183l7.9 19786.6 16478.0 17205.5
1952 4592.9 2170.1 1501.0 1274.5 841.0 735.0 803.9 4216.5 25773.4 22110.9 17356.3 11571.0
1953 6285.7 2756.8 1281.2 818.9 611.7 670.7 1382.0 15037.2 21469.8 17355.3 16681.6 11513.5
1954 4218.9 1599.6 1183.8 1087.8 803.1 638.2 942.6 11696.8 19476.7 16983.6 20420.6 9165.5
1955 3859.2 2051.1 1549.5 1388.3 1050.5 886.1 940.8 6718.1 24881.4 23787.9 23537.0 13447.8
1956 4102.3 1588.1 1038.6 816.9 754.8 694.4 718.3 12953.3 27171.8 25831.3 19153.4 13194.4
1957 4208.0 2276.6 1707.0 1313.0 1189.0 935.0 945.1 10176.2 25275.0 19948.9 17317.7 14841.1
1958 6034.9 2935.9 2258.5 1480.6 1041.7 973.5 1265.4 9957.8 22097.8 19752.7 10843.4 5978.7
1959 3668.0 1729.5 1115.1 1081.0 949.0 694.0 885.7 10140.6 18329.6 20493.1 23940.4 12466.9
1960 5165.5 2213.5 1672.3 1400.4 1138.9 961.1 1069.9 13044.2 13233.4 19506.1 19323.1 16085,()
1961 6049.3 2327.8 1973.2 1779.9 1304.8 1331.0 1965.0 13637.9 22784.1 19839.8 19480.2 10146.2
1962 4637.6 2263.4 1760.4 1608.9 1257.4 1176.8 1457.4 11333.5 36017.1 23443.7 19887.1 12746.2
1963 5560.1 2508.9 1708.9 1308.9 1184.7 883.6 776.6 15299.2 20663.4 28767.4 21011.4 10800.0
1964 5187.1 1789.1 1194.7 852.0 781.6 575.2 609.2 3578.8 42841.9 20082.8 14048.2 7524.2
1965 4759.4 2368.2 1070.3 863.0 772.7 807.3 1232.4 10966.0 21213.0 23235.9 17394.1 16225,6
1966 5221.2 1565.3 1203.6 1060.4 984.7 984.7 1338.4 7094.1 25939.6 16153.5 17390.9 9214.1
1967 3269.8 1202.2 1121.6 1102.2 1031.3 889.5 849.7 12555.5 24711.9 21987.J 26104.5 13672.9
1968 4019.0 1934.3 1704.2 1617.6 1560.4 1560.4 1576.7 12826.7 25704.0 22082.8 14147.5 7163.6
1969 3135.0 1354.9 753.9 619.2 607.5 686.0 1261.6 9313.7 13962.1 14843.5 7771.9 4260.0
1970 2403.1 1020.9 709.3 636.2 602.1 624.1 986.4 9536.4 14399.0 18410.1 16263.8 7224.1
1971 3768.0 2496.4 1687.4 1097.1 777.4 717.1 813.7 2857.2 27612.8 21126.4 27446.6 12188.9
1972 4979.1 2587.0 1957.4 1670.9 1491.4 1366.0 1305.4 15973.1 27429.J 19820.3 17509.5 10955.7
1973 4301.2 1977.9 1246.5 1031.5 1000.2 873.9 914.1 7287.0 23859.3 16351.1 18016.7 8099.7
1974 3056.5 1354.7 931.6 786.4 689.9 627.3 871.9 12889.0 14780.6 15971.9 13523.7 9786.2
1975 3088.8 1474.4 1276.7 1215.8 1110.3 1041.4 1211.2 11672.2 26689.2 23430.4 15126.6 13075.3
1976 5679.1 1601.1 876.2 757.8 743.2 690.7 1059.8 8938.8 19994.0 17015.3 18393.5 5711.5
1977 2973.5 1926.7 1687.5 1348.7 1202.9 1110.8 1203.4 8569.4 31352.8 19707.3 16807.3 10613.1
1978 5793.9 2645.3 1979.7 1577.9 1267.7 1256.7 1408.4 11231.5 17277.2 18385.2 13412.1 7132.6
1979 3773.9 1944.9 1312.6 1136.83 1055.4 1101.2 1317.9 12369.3 22904.8 24911.7 16670.7 9096.7
1980 6150.03 3525.03 2032.0 3 1470.0 1233.0~ 1177.0 3 1404.0~10140.0 3 23400.0 26740.0:z.18000.02.11000.02..
1981 6458.0;1'. 3297.02 1385.04 1147.01 971.0'~-889.04 1103.0 10406.04 17323.0 .. 27840'.0 31435.0 12026.0
AVE 4513.1 2052.4 1404.8 1157,3 978.9 898.3 1112.6 10397.6 22922.4 20778,0 18431.4 10670.4
Notes: (1) Discharges based on Cantwell and Gold Creek flows unless specified
(2) Watana observed flows
(3) Flows based on Gold Creek
(4) Watana long-term average flows assumed
J
AVE
6599.5
7696.1
7745.5
7908.7
i351. 4
86/4,8
9001.5
83~9.4
7718.4
7957.7
7901.2
8551.6
9799.1
9206.1
8255.4
8409.0
7345.9
9041.5
7991.4
4880.8
6068.0
8549.1
8920.4
7079.9
6272.5
8367.7
6788.4
8208.6
6947.4
8:1.33.0
88!55.9
9523.3
7943.1
l
-~
TABLE 7.9: DEVIL CANYON ESTIMATED NATURAL FLOWS
YEAR OCT NOV IIEC ~IAN FE£; MAR AF'F: MAY JUN JUL AUG SEP AVE
1950 5758.2 2404.7 1342.5 951.3 735.7 670.0 t\ '", "') 10490.7 18468.6 21383.4 18820.6 7950.8 7481.6 oV-'--t~
1951 3652.0 1231.2 1030.8 905.7 767.5 697.1 1504.6 13218.5 19978.5 ~1575i9 18530.0 19799.1 8574.2
1952 5221.7 2539.0 1757.5 1483.7 943.2 828.2 878.5 4989.5 30014.2 24861.7 19647.2 13441.1 8883.8
1953 7517.6 3232.6 1550,4 999.6 745.6 766.7 1531.8 17758.3 25230.7 19184.0 19207.0 13928.4 9304.4
1954 5109.3 1921.3 1387 t 1 1224.2 929.7 729.4 1130.6 15286.0 23188.1 19154.1 24071.6 11579.1 8809.2
1955 4830.4 2506.8 1868.0 1649.1 1275.2 1023.6 1107.4 8390.1 28081.9 26212.8 24959.6 13989.? 9657.8
1956 4647.9 1788.6 1206.6 921.7 893.1 852.3 867.3 15979.0 31137.1 29212.0 22609.8 16495.8 10550.9
1957 5235.3 2773.8 1986.6 1583.2 1388.9 1105.4 1109 t 0 12473.6 28415.4 22109.6 19389.2 18029.0 9633.3
1958 7434.5 3590.4 2904.9 1792.0 1212+2 1085.7 1437.4 11849.2 24413.5 21763.1 21219.8 6988.8 8807.6
1959 4402.8 1999.8 1370.9 1316.9 1179.1 877.9 1119,9 13900.9 21537.7 23390.4 28594.4 15329.6 9585.0
1960 6060.7 2622.7 2011.5 1686.2 1340.2 1112.8 1217.8 14802.9 14709.8 21739.3 22066.1 18929.9 9025.0
1961 7170.9 2759.9 2436.6 2212.0 1593.6 1638.9 2405.4 16030.7 27069.3 22880.6 21164.4 12218.6 9965.1
1962 5459.4 2544.1 1978.7 1796.0 1413.4 1320.3 1613.4 12141.2 40679.7 24990ttl 22241.8 14767.2 10912.2
1963 6307.7 2696.0 1896.0 1496.0 1387.4 958.4 810.9 17697.6 24094.1 32388.4 22720 ~~i 11777 •. 2 10352.5
1964 5998.3 2085.4 1387.1 978.0 900.2 663.8 696.5 4046.9 47816.4 21926.0 15585.8 8840.0 9243.7
1965 5744.0 2645.1 1160.8 925.3 828.8 866.9 1314.4 12267.1 24110.3 26195.7 19789.3 18234.2 ~~506 + 8
1966 6496.5 1907.8 1478.4 1278.7 1187.4 1187.4 1619.1 8734.0 30446.3 18536.2 20244.6 10844.3 8663.4
1967 3844.0 1457.9 1364.9 1357.9 1268.3 1089.1 1053.7 14435.5 27796.4 25081.2 30293.0 15728.2 10397.5
1968 4585.3 2203.5 1929.7 1851.2 1778 t 7 1778.7 1791.0 14982.4 29462.1 24871.0 16090.5 8225.9 9129.2
1969 3576.7 1531.8 836.3 686.6 681 .s 769.6 1421.3 10429.9 14950.7 15651.2 8483.6 4795.5 5317.9
1970 2866.5 1145.7 810.0 756.9 708,.7 721.8 1046.6 10721.6 17118.9 21142.2 18652.8 8443.5 7011.3
1971 4745.2 3081.8 2074.8 1318.8 943.6 866.8 986.2 3427.9 31031.0 22941.6 30315.9 13636.0 9614.1
1972 5537.0 2912.3 2312.6 2036.1 1836.4 1659.8 156So5 19776.8 31929.8 21716.5 18654.1 11884.2 10151.8
1973 4638.6 2154.8 1387.0 1139 .s 1128.6 955.0 986.7 7896.4 26392.6 17571.8 19478.1 8726.0 7704.6
1974 3491.4 1462.9 997.4 842.7 745.9 689.5 949.1 15004.6 16766.7 17790.0 15257.0 11370.1 7113.9
1975 3506.8 1619.4 1486.5 1408,8 1342.2 1271.9 1436.7 14036.5 30302.6 26188.0 17031.6 13154.7 9367.1
1976 7003.3 1853,0 1007.9 896.8 876.2 825.2 1261.2 11305.3 22813.6 18252.6 19297.7 .:.463.3 7654.7
1977 3552.4 2391.7 2147.5 1657.4 1469.7 1361.0 1509.8 11211.9 35606.7 21740.5 18371.2 11916.1 9411.3
1978 6936.3 3210.8 2371.4 1867,9 1525.0 1480.6 15?7 .1 11693.4 18416.8 20079.0 15326.5 8080.4 7715.4
197~ 4502.3 2324.3 1549.4 1304.1 1203.6 1164.7 1402.8 13334.0 24052.4 27462.8 19106.7 HH72.4 8965.0
198 6900,0 3955.0 2279.0 1649.0 1383.0 1321.0 1575.0 11377.0 26255.0 30002.0 20196.0 12342.0 9936.2
1981"~ 7246.0 3699.0 1554.0 1287.0 1089.0 997.0 1238.0 11676.0 19436.0 3123t..o 35270.0 13493.0 10685.1
AVE 5311.8 2382.9 1652.0 1351.9 1146.9 1041.8 1281.5 12230t2 25991.3 23100.9 20709.0 12299.2 9041.6
* Discharges based on Watana flows
TABLE 7.10: PEAK FLOWS OF RECORD
p;;·-,
Gold Creek Can hell Denali Maclaren
Peak Peak Peak Peak
3 3 3 3
Date ~ Date ft /s Date ft /s Date ft /s p-:"'.
8/25/59 62,300 6/23/61 30,50D 8/18/63 17,00D 9/13/60 8,90D
6/15/62 80,600 6/15/62 47,000 6/07/64 16,DOO 6/14/62 6,650
6/D7/64 90,7DO 6/D7/64 5D,5DD 9/09/65 15,800 7/18/65 7,35D
6/06/66 63,6DO 8/11/7D 20,500 8/14/67 28,200 8/14/67 7 ,6DD
8/15/67 8D,2DO 8/1D/71 60,00D 7/27/68 19,DOD 8/10/71 9,30D
8/1 D/71 87,4DO 6/22/72 45,000 8/08/71 38,200 6/17/72 7 '100
TABLE 7.11: ESTIMATED FLOOD PEAKS IN SUSITNA RIVER
Location Peak Inflow in Cfs for Recurrence Interval in Years
1:2 1:50 1:1DD 1: 101 ODD PMF
Gold Creek 48,DDD 1 D5, DOO 118,DDD 2DO,DDO 4D8,DDD
Watana Damsite 42,DDD 82,DOD 92,000 156,DOD 326,0DD
De·vil Canyon Damsite ) 12,600 43,DOD 61,00D 165,DOO 346,0DD
(Routed Peak Inflow )
with Watana )
~-
-
-I
-
TABLE 7.12: MAXIMUM RECORDED ICE THICKNESS ON THE SUSITNA RIVER
Historical Data Current Program
Maximum Ice Thickness Year of Maximum Ice Thickness
Location Period of Record (Feet Observation Observed in 1980
(feet)
Maclaren River at Paxson 1960-68 5.2 1964 -
Susitna River at Cantwell 1962-70 5.3 1967 10.0
Susitna River at Gold Creek 1950-70 5.7 1963 3.2
Talkeetna River at Talkeetna 1966-71 3.3 1969 -
Chulitna River at Talkeetna 1961-72 5.3 1971 -
Watana Damsite 1980-81 NA -5.0
Devil Canyon 1980-81 NA -23.0*
* Ice shelf thickness -notice cover.
TABLE 7.13: SUSPENDED SEDIMENT TRANSPORT IN SUSITNA RIVER
Location
Susitna River at Denali
Maclaren River near Paxson
Susitna River near Cantwell
Susitna River at Gold Creek
Average Annual Suspended
Sediment load (tons/year)
2,965,000
543,000
6,898,000
7, 731 ,DOD
TABLE 7.14: ESTIMATED SEDIMENT DEPOSITION IN RESERVORS
Sediment Deeosition
Trap 50 -Year 100 -Year
Efficiency Deposit ion % of Reservoir Deposition % of Reservoir
Reservoir % ac -ft Gross Volume ac -ft Gross Volume
Watana 100 240,000 2.5 472, DOD 5.0 t~''
70 170,000 1.8 334,000 3.5
Dev il Canyon 100 8,600 0.8 16,800 1.5
(with Watana 70 6,100 0.6 12,100 1 • 1
1 DO%)
Devil Canyon 100 79,000 7.2 155,000 14.2
(with Watana 70 55' 000 5.0 109,000 1 D. 0
70%)
r
r
' l
r
I
(
r
TABLE 7.15: WATER APPROPRIATIONS WITHIN ONE MILE OF THE SUSITNA RIVER
ADD I T I UNAL (g~~~~) LOCATION* NUMBER TYPE AMOUNT DAYS OF USE
CERTIFICATE
T 19N RSW 45156 Single-family dwelling well (?) 650 gpd 365
general crops same source 0. 5 ac-ft/yr 91
T25N RSW 43981 Single-family dwelling well (90 ft) 500 gpd 365
T26N RSW 78895 Single-family dwelling well (20 ft) 500 gpd 365
200540 Grade school well ( 27 ft) 910 gpd 334
209233 Fire station well ( 34 ft) 500 gpd 365
T27N RSW 200180 Single-family dwelling unnamed stream 200 gpd 365
Lawn & garden irrigation same source 100 gpd 153
200515 Single-family dwelling unnamed lake 500 gpd 365
206633 Single-family dwelling unnamed lake 75 gpd 365
206930 Single-family dwelling unnamed lake 250 gpd 365
206931 Single-family dwelling unnamed lake 250 gpd 365
PERMIT ---
206929 General crops unnamed creek 1 ac-ft/yr 153
T30N R3W 206735 Single-family dwelling unnamed stream 250 gpd 365
PENDING
209866 Single-family dwelling Sherman Creek 75 gpd 365
Lawn & garden ir rig at ion same source 50 gpd 183
*All locations are within the Seward Mer .idian.
TABLE 7.16: HECTARES AND PERCENTAGE OF TOTAL AREA COVERED BY
VEGETATION/HABITAT TYPES
Hectares
Total Vegetation 1' 387' 607 8).08
Forest 348,232 21.3)
Conifer 307' )86 18.86
Woodland spruce 188' 391 11.))
Open spruce 118,873 7.29
Closed spruce 323 0.02
Deciduous 1' 290 0.08
Open birch 968 0.06
Closed birch 323 0.02
Mixed 39,3)) 2.41
Open 23,387 1.43
Closed 1 s, 968 0.98
Tundra 394,68) 24.20
Wet sedge-grass 4,839 0.30
(Mesic) sedge-grass 184, 3)8 11.30
Herbaceous alpine 807 0.0)
Mat and cushion 6),001 3.99
Mat and cushion/sedge-grass 139,680 8.)6
Shrub land 644,690 39. )3
Tall shrub 129,03) 7.91
Low shrub )1),6)) 31.62
Birch 33,)49 2.06
Willow 10,64) 0.65
Mixed 471,461 28.91
Unvegetated 243,392 14.92
Water 39,840 2.44
Lakes 2),162 1. )4
Rivers 14,678 0.90
Rock 113,712 6.97
Snow and ice 89,841 ).)1
Total Area 1,630,999 100. DO
r."·~;
~,'Yr
i!W''''"'--
~".''•\
~""
rr .... , .. ,_
~l
cOOl< INLeT
0671>
0
--~
0 I
'
0NENANA
HEALY
00671
PALMER
00688
DATA COLLECTION STATIONS
~ ·"' •
"'""
DaTA
0 0675
•
RAPIDS
0 0674
PAXSON
'-<;--..------~ 0 0676 \
GULKANA0 0617
o.863
STATION
(Al SUSITN~ RIVER NEAR DENALI
18) SUSITNA·' RIVER AT VEE CANYON
{Cl SUSITNA~ RIVER
I
NEAR WATANA DAMSITE
(OJ SUSITNAI RIVER
I
NEAR DEVIL CANYON
~:~ ~~::~JAR:~:ER ATN~ORLO TACLRK:NA
(G) TALKEE,:NA RIVER NEAR TALKEETNA
{Hl SUSITNA RIVER NEAR SUNSHINE
{I l SKWENTNA RIVER NEAR SKWENTNA
IJ) YENTNAi RIVER NEAR SUSITNA STATION
{K) SUSITNA: RIVER AT SUSITNA STATION
I
I
I
I
I
X X
X X X
X X x•
X X
X X
X
X X
X
X X
X
X X
~!I: ~i
&~
§~ -~ !Jj~ •. o
X X X X X 1957-PRESENT
X X (1961 -1972 a
1980-PRESENT
X X X X X 1980-PRESENT
X X
X X X 1949-PRESENT
X X X [1958 -1972 tl
1980-PRESENT
X X X 1964-PRESENT
X X X 1981 -PRESENT
X X X 1959-1980
X X 1980-PRESENT
X X 1974-PRESENT
DATA COLLECTED
INDEX NUMBERING
• STREAMFLOW -CONTINUOUS RECORD 0100
[J STREAMFLOW-PARTIAL RECORD 0200
e WATER QUALITY 0300
T WATER TEMPERATURE 0400
tlt SEDIMENT DISCHARGE
0 CLIMATE
-FREEZING RAIN AND INCLOUD ICING
SNOW COURSE
" SNOW CREEP
NOTES
0!500
0600
0700
0800
0900
I. PARAMETERS MEASURED LISTED IN APPENDIX Bl
2.. CONTINUOUS WATER QUALITY MONITOR INSTALLED
3. DATA COLLECTION 1981 SEASON
4. THE LETTER BEFORE EACH STATION NAME IN THE
TABLE IS USED ON THE MAP TO MARK THE
APPROXIMATE LOCATION OF THE STATIONS.
5. STATION NUMBERS UNDERLINED INDICATES DATA COLLECTED
BY STUDY TEAM IN 19.80-82. SNOW COURSES MEASURED
ARE NOT UNDERLINED FOR CLARITY.
0 10 20 MILES
SCALE
(APPROX.)
FIGURE 7.1
-
r
!
l !
r
l
r
r
-I
-
YENTNA RIVER
COOK INLET
SUSITNA RIVER
GOLD CREEK
WATANA
SITE
PARKS HIGHWAY BRIDGE
GAGING STATION
SUSITNA GAGING STAT~
AVERAGE ANNUAL FLOW DISTRIBUTION
WrTHIN THE SUSITNA RIVER BASIN
FIGURE 7.2
~ ~ 1 ,-~--~1 1 ---~1 '-::-c~1 c -~ l ·-~---~, ,.--~ --~---1 ------c-1 '"'' ----, ~---~-----l --~~---] 1 -1 -, 1 ----~ -~ l --}.
50,000
LEGEND
0 40,000 WETTEST YEAR-1962
z
0
0 AVERAGE YEAR w en
0::: w a.. DRIEST YEAR -1969
1-30,000 w w
LL.
0
CD :::>
0 -
3: 20,000
0
_J
LL.
~
<(
w
0:::
1-en
10,000
0
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
MONTHLY AVERAGE FLOWS IN
THE SUSITNA RIVER AT GOLD CREEK
FIGURE 7.3
-i
'"""
i
I t
-I
I
.....
-
,.....
I
-
..,
0
)(
.......
(/)
1.1.
u
LLI
(!)
0::
<(
:I: u
(/)
0
56.
o.oL----r---r--------r--.-~::::::::=::;::::::::;::=::~
0.00 0.20 0.40 0.60
PROS OF EXCEEDENCE
FLOW DURATION CURVE
MEAN MONTHLY INFLOW
AT WATANA
PRE-PROJECT
0.80 1.00
FIGURE 7.4
-I
I
"""'
-
f""''
fl"""
1""'
-i
J
cO-
-
-I
r
\
,.,
0 -
)(
(J')
u.. u
LLI
(!)
0::
<t
::t: u
(J')
0
56.0
48.0
40.0
32.0
24.0
16.0
0.00 0.20 0.40 0.60
PROB OF EXCEEDENCE
FLOW DURATION CURVE
MEAN MONTHLY INFLOW
AT DEVIL CANYON
PRE-PROJECT
0.80 1.00
FIGURE 7.5
,-~ ~-1 ~-~, r~-----'l ''c'••. '1 ~ ---~
20
p -r-r---I-.
ltl
0
J( 10
(/) 9
t
_@>
u. 8 u
~ 7
0
...J 6 u.
ci 5 > r---
<(
4 f------c-
3
0.01 0.1 0.2 0.5
,~------) ,.,...-~--c 'l ('---1 1 '""""~ l !'7------~l ,-<"--~-l --1 ,----1 1 ,.-.-~ ·-----~ l l
RETURN PERIOD IN YEARS
1.11 L25 2 5 10 100 1000 10,000
~ '---
r---.....___
~ MIN. 3 YR. AVG. FLOW RECORDED ...._
;· -r--:: 11 ----t---'i ~-r------r----
--~-----~---1---
---;;
MIN. ANNUAL FLOW RECORDED
co-
2 5 10 20 30 40 50 60 70 80 90 95 98 99 99.8 99.9 99.99
PERCENT PROBABILITY OF EXCEEDENCE
ANNUAL FLOW DURATION FREQUENCY CURVES
SUSITNA RIVER AT GOLD CREEK
@ INDICATES CURVE FOR 3-YR. AVERAGE FLOWS
FIGURE 7.6
l
,...
r""
,....
-
I"""
I
J-
I
i
'
r-
-
r
-
-
r
I
,_
I
[
90
80
70
60
-rt) 50
Q
"' (f)
u..
u
~
0
...J u.. 40
30
20
10
0
l
0
A
I\
I \
v " ~ I
/
/
5 10 15 20 25
TIME (DAYS)
I: 50 YEAR ANNUAL FLOOD INFLOW HYDROGRAPH
SUSlTNA RIVER AT WATANA DAM SITE
30
FIGURE 7.7
180
-
-160
140
J \
v \ 120
,.....
l ~ 100 rt) i Q
I ~
>< ,...., (/)
\ IL
I (.)
~
9
r'" IL eo \_
r--....
-
-
/
I v
60
40
20 /
0
0 5 10 15 20 25 30
TIME (DAYS)
I!*'
!
i.
1:10000 YEAR FLOOD INFLOW HYDROGRAPH E
SUSITNA RIVER AT WATANA. DAM SITE 100£0
FIGURE 7.8 HUU[O
-\
r
r
'
,....
I ! L
r-
j
,....
i.
!
!"""
!"""'
!
-!
,.....
I
l
360
320
280
240
,;;2oo
Q
)(
~ s
~
0
...J
LL. 160
120
80
40
0
0
A
\
\
I,J
I
\
I
\
~
I
v
/
5 10 15 20 25
TIME (DAYS)
PROBABLE MAXIMUM FLOOD INFLOW HYDROGRAPH
SUSITNA RIVER AT WATANA DAM SITE
"'
30
FIGURE 7.9
..,
0
60
50
40
30
20
~10
0 9
:r: 8
g 7
LL.
6
5
4
2
1.5
I-"!
I
...,.
__ ..... .,./
\ SUSITNA RIVER AT GOLD CREEK / ,..... ......
~ / ... .... .,
\ v v ,....,. ......... v ,.....
~ / ~ "'1\!.. SUSITNA RIVER AT CANTWELL v
~ ~ .......... I--"'
~ ~ ~.-~
11 1.---v ~
!.---' v SUSITNA RIVER AT DENALI _.,... v ~ _,...
v -~.---"" ./ 1.----
~ v v ......
~_...........---~ __ ,. ~ ..
~ /' )...--",.,. \
~ _,/ ..,...... ....
~MACLAREN RIVER AT PAXON ........ I--
v ~ ~ ~ v
---!.---' v ./ I./ ! v v
h ~
~
2 4 ~ 6 7 8 9 10 20 30 40 50 60 70 80 90 100
SUSPENDED SEDIMENT DISCHARGE {TONS/DAY) x 10 3
SUSPENDED SEDIMENT TRANSPORT
SUSITNA RIVER AT SELECTED STATIONS
I
120 130 140
FIGURE 7.10
1
~-,
T
32
N
T
31
N
T
30
N
~, "~~ "l 1 c~c~ccl 1 ~1 "Co"~~, '""1 "''"""'"-"1 ~,~,
....
CENOZOIC
QUATERNARY ,---,
L_ ___ ~
TERTIARY
w--·~,
I + + i a.... __ --.J
MESOZOIC
CRETACEOUS
r:==~===-:-:=3 t..-=--=----=--...
JURASSIC
illTIIITO
l 1 ----,--l 1 "1 -l J
LEGEND
UNDIFFERENTIATED SURFICIAL DEPOSITS
UNDIFFERENTIATED VOLCANICS a SHALLOW
INTRUSIVES
GRANODIORITE,
BIOTITE-HORNBLENDE GRANODIORITE,
BIOTITE GRANODIORITE
SCHIST, MIGMATITE, GRANITIC ROCKS
UNDIVIDED GRANITIC ROCKS
MAFIC INTRUSIVES
ARGILLITE AND LITHIC GRAYWACKE
fl<:l':AAI'J.
t66.6.~~
TRIASSIC
~L"7-""'7,(;1
~:!..::_"_!.J
PALEOZOIC
AMPHIBOLITES, GREENSCHIST, FOLIATED DIORITE
BASALTIC METAVOLCANIC ROCKS, METABASALT
AND SLATE
BASALTIC TO ANDESITIC META VOLCANICS LOCALLY
INTERBEDDED WITH MARBLE
THRUST FAULT TEETH ON UPTHROWN SIDE,DASHED WHERE I
---,.--.,.' • DOTTED WHERE CONCEALED
INTENSE SHEARING , FQSSIBLE THRUST FAULT, TEETH ON UPTHROWN • • V" • • • \7 • • 51 DE
PROPOSED DAM SITES
0 4 8
GRANODIORITE, QUARTZ DIORITE, TRONDHJEMITE
SCALE IN MILES
REGIONAL GEOLOGY FIGURE 7.11
)
--~ .. ,
A. TALKEETNA TERRAIN MODEL
LEGEND
Mapped strike·slip fault, arrows show
~nse of horizontal displacement
Mapped strike-slip fault with dip slip
component, letters show sense of
vertical displacement: U is up;
0 is down.
Mapped fault, sense of horizontal
displacement not defined
Inferred strike-slip fault
Mapped thrust fault, sawteeth on
upper plate
WOODWARD-CLYDE CONSULTANTS 41410A February 1982
NOTES
Q) 0.9 -2.0 cm/yr Hickman and Campbell (1973); and Page (1972).
@ 0.5 -0.6 cm/yr Stout and others (1973).
@ 3.5 cm/yr Richter and Matson (1971).
@) 1.1 em/yr. no Holocene activity farther east, Richter and Matson (1971).
® 0.9 -3.3 cm/yr Richter and Matson (1971 ).
@ Inferred connection with Dalton fault; Plafker and others (1978).
('j) Inferred connection with Fairweather fault; Lahr and Plafker (1980).
@ Connection inferred for this report.
@ 0.1-1.1 cm/yr Detterman and others (1974); Bruhn (1979).
® 5.8 cm/yr Lahr and Plafker (1980).
(p Aleutian Trench and Postulated Shelf Edge Structure ·after Guptill
and others (1981).
@ Slip rates cited in. notes CD through @ are Holocene slip rates.
@ All fault locations and sense of movement obtained from Beikman (1978; 1980).
1 l
B. SCHEMATIC TALKEETNA TERRAIN SECTION
Btnioff z.,,.
S.i•moootv
]
0 100 200 Miles
E::~~>--<~~~1 ~~~
0 100 zOo Kilomelers
TALKEETNA TERRAIN MODEL
AND SECTION
FIGURE 7.12
1 1
~O>r---~l~~~---------------------------1~5~1~0 --------------------------~1~00~0---------------------------~14~9~0--------------------------~~~
1":!0
/
/GENERALIZED ~WESTERN BOUNDARY / "' "' '""'"' "'""
(
\
I
\,
Mt Yenlo
.--Vc _.,~Unconformity
0 5 Miles
~~
0 5 Kilometers
D)
·'u\ /
.......... '-.. V~94 API CENTER
'-..{' Ms 7.3
\ / '-.....,h = 17 km
"-.._
(
I \ ' ""-\ ' _.-
/ \ " " _........._......... <s ~ ..------
/ / km radt::... :1_ L ,:-u~'~' p.l\'1
;r~" v···
J
WOODWARD-CLYDE CONSULTANTS 41410A February 1982
8'
o!;,........=:~3:':ili3S;:::;::,~=~5 Miles r 5 Kilometers
··-.1
LEGEND
Tv Tertiary volcanic rocks
Kag Cretaceous argillite and graywacke
KJs Cretaceous -Jurassic marine sedimentary roci(s,
undivided
Vc Paleozoic and Triassic rocks (inferred from
aeromagnetic datal
Pzv Paleozoic volcanic rocks
u .•. p
u,.....-·
%D ...
A
A.
D.··
•• ··u
W8, W9
WI
D I
NOTES
Inferred lithologic contact
Strike-slip fault with recent displacement,
arrows show sense of horizontal displacement,
letters show sense of vertical displacement:
U is up; D is down, dotted where concealed
Strike-slip fault without recent displacement,
dashed where inferred, dotted where concealed.
Thrust fault without recent displacement,
dashed where inferred, dotted where concealed,
sawteeth on upper plate
Line separating aeromagnetically dissimilar
terrain, dashed where indistinct
U~2 I ineament
LANDSAT lineament
Inferred fault from aeromagnetic data,
letters show sense of vertical displacement,
U is up; D is down
Locations studied during this investigation
Watana Site
Devil Canyon Site
1. Line separating aeromagnetically dissimilar terrain and
Mt Yenlo geology are shown by, or interpreted from
Csejtey and others (19781 and Griscom (19791.
2. The Talkeetna thrust fault and adjacent geology
are from Csejtey and others (1978).
3. Castle Mountain fault location is from Magoon
and others (19761.
4. The 1943 epicenter location is from analysis con-
ducted during this investigation (Section 5.1.3) and
Tobin and Sykes (1966). h is the focal depth of
this earthquake.
5. Locations WB and W9 are shown in Figure 4~7
and discussed in Sections 4.4.1 and 5.1 .3.
0 5 10 20Miles s:::g;;:; I E"""""""=31
0 10 20 30 Kilometers
1943 EARTHQUAKE GEOLOGY MAP II ·~D(O I
FIGURE 7.13 Hun o
.... ]
LEGEND
m WATANA PACK
~ TYONE PACK
IIIIIIII1 SUSITNA PACK
~ TOLSONA PACK
-[I J SUSPECTED PACK _..J
0 20 40
SCALE IN MILES
LOCATION AND TERRITORIAL BOUNDARIES OF WOLF PACKS -1980
FIGURE 7.14
/ ~-j
DIVISIONS OF NELCHINA CARIBOU HERD RANGES
(UNITS BASED UPON TOPOGRAPHY, VEGETATION AND USE)
MODIFIED FROM SKOOG 1968
WRANGELL MTS
0
MENTASTA
MTS
25 50
SCALE-MILES-APPROXIMATE
FIGURE 7.15
-1 .-·--l -1
LEGEND
CENSUS AREA
D ZERO DENSITY
D LOW DENSITY . .
~ MEDIUM DENSITY
~ HIGH DENSITY
0 20 40
SCALE IN MILES
RELATIVE DENSITIES OF MOOSE-NOVEMBER, 1980
FIGURE 7.16
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1-
EMPLOYMENT
2500 LEGEND
2000 -MAT SU BOROUGH
1500 VALDEZ-WHITTIER-
CHITINA CENSUS DIVISION
1000
500
1970 71 72 73 74 75 76 77 78 79 80
(YEAR)
20 POPULATION
15
10 ---
---/
5 -,_.,.....,.,.
1970 71 72 73 74 75 76 77 78 79 80
(YEAR)
PER CAPITA PERSONAL INCOME ,,
20 I \
I \
I \ 16 / \
/ \ / 12 /
/ ......... ...;
/
8 / ----4
1970 71 72 73 74 75 76 77 78 79 80
(YEAR)
EMPLOYMENT, POPULATION AND PER CAPITA PERSONAL INCOME
lN THE MATANUSKA-SUSlTNA BOROUGH AND VALDEZ-
WHITTIER-CHITlNA CENSUS DlVlSION, l970 -l980
FIGURE 7.17
-c-~ ~·-~--..... 1 ,.~-·1 .. -·1 -] 1 --) ---· 1 , ... -.~~01 "'~""~"1 =~~~1 "~~~, ~~~1 =·~, ~~~., --, ··----1 ~-l ·~
···~ .. \' :.'<~. ~~'·'-
NABESNA
COMMUNITIES IN VICINITY OF SUSITNA BASIN
FIGURE 7.18
~--l ,----1 ~----1 --1 -~1 ~--. ---~1 r~-""] ~-""] ---, -·----~ ,--, ----"1 ""'"'-""] ,--~1 ----·] 1 ~ "l ----1
EXISTING STRUCTURE(S) ...• .._
0 10 20 MILES
SCALE
EXISTING STRUCTURES
FIGURE 7.19
"~--1 1 ~ -, J ] ~ ~ 1 c --] 1 ' "] c ~ --, ' ~-] ] . ~~ ~~, "] I ~·"•~~l ~~] l r"'-•-l -1
NO. USE INTENSITY
I. RECREATION MEDIUM
2. MINING MEDIUM
3. RECREATION MEDIUM
4. MINING/RESID HIGH
~-MINING HIGH
6. REC./RESID HIGH
7. RECREATION HIGH
8. RECREATION LOW
9. RECREATION MEDIUM
10. RECREATION MEDIUM
II. RECREATION LOW
0 10 20 MILES
SCALE
-------------
LAND USE AGGREGATIONS
FIGURE 7.20 I~~~(~ I
~~
-
8 -SUSITNA BASIN DEVELOPMENT SELECTION
This section of the report outlines the engineering and planning stu-
dies carried out as a basis for formulation of Susitna Basin develop-
ment plans and selection of the preferred plan.
In the description of the planning process, certain plan components and
processes are frequently discussed. It is appropriate that three par-
ticular terms be clearly defined:
(a) Dams ite
(b) Basin Development
Plan
(c) Generation
Scenario
-An individual potential damsite in the Susit-
na Basin, referred to in the generic process
as 11 candidate.11
-A plan for developing energy within the Upper
Susitna Basin involving one or more dams,
each of specified height, and corresponding
power plants of specified capacity. Each
plan is identified by a plan number and sub-
number indicating the staging sequence to be
followed in developing the full potential of
the plan over a period of time.
A specified sequence of implementation of
power generation sources capable of providing
sufficient power and energy to satisfy an
e 1 ectri c 1 oad growth forecast for the 1980-
2010 period in the Railbelt area. This se-
quence may include different types of genera-
tion sources such as hydroelectric and coal,
gas or oil-fired thermal. These generation
scenarios were developed for the comparative
evaluations of Susitna Basin generation ver-
sus alternative methods of generation.
8.1 -Plan Formulation and Selection Methodology
In apply-ing the generic plan formulation and selection methodology,
five basic steps are required; defining the objectives, selecting can-
didates, screening, formulation of development plans, and, finally, a
detailed evaluation of the plans (see Figure 8.1). The objective is to
determine the optimum Susitna Basin development plan. The var·ious
steps required are outlined in subsections of this section.
Throughout the p 1 anni ng process, engi neer·i ng 1 ayout studies were made
to refine the cost estimates for power generation facilities or water
storage development at several damsites within the basin. These data
were fed ihto the screening and plan formulation and evaluation stu-
dies.
8-1
The second objective, the detailed evaluation of the various plans, is
satisfied by comparing generation scenarios that include the selected
Susitna Basin development plan with alternative generation scenarios
including all-thermal and a mix of thermal plus alternative hydropower
developments.
8.2 -Damsite Selection
In previous Susitna Basin studies (see Section 4), twelve damsites have
been identified in the upper portion of the basin, i.e., upstream from
Gold Creek. These sites are listed in Table 8.1 with relevant data
concerning facilities, cost, capacity, and energy.
The longitudinal profile of the Susitna River and typical reservoir
levels associated with these sites is shown in Figure 8.2. Figure 8.3
illustrates which sites are mutually exclusive, i.e., those which can-
not be developed jointly, since the downstream site would inundate the
upstream site.
All relevant data concerning dam type, capital cost, power, and energy
output were assembled and are summarized in Table 8.1. For the Devil
Canyon, High Devil Canyon, Watana, Susitna III, Vee, Maclaren, and
Denali sites, conceptual engineering layouts were produced and capital
costs were 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; data from previous studies were used with capital cost
estimates updated to 1980 levels. Approximate estimates of the poten-
tial average energy yield at the Butte Creek and Tyone sites were un-
dertaken to assess the relative importance of these sites as energy
producers.
The data presented in Table 8.1 show that Devil Canyon, High Devil
Canyon, and Watana are the most economic large energy producers in the
basin. Sites such as Vee and Susitna III have only medium energy pro-
duction, and are slightly more costly than the previously mentioned
damsites. Other sites such as Olson and Gold Creek are competitive
provided they have additional upstream regulation. Sites such as
Denali and Maclaren produce substantially higher cost energy than the
other sites but can also be used to increase regulation of flow for
downstream use.
8.3 -Site Screening
The objective of this screening process was to eliminate sites which
would obviously not feature in the initial stages of a Susitna Basin
development plan and which, therefore, did not deserve further study at
this stage. Three basic screening criteria were used: environmental,
alternative sites, and energy contribution.
8-2
,...
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The screening process involved eliminating all sites falling in the
unacceptable environmental impact and alternative site categories.
Those failing to meet the energy contribution criteria were also
eliminated unless they had some potential for upstream regulation. The
results of this process, described in detail in the Development Selec-
tion Report (1), are as follows:
-The 11 Unacceptable site11 environmental category eliminated the Gold
Creek, Olson, and Tyone sites.
-The alternative sites category eliminated the Devil Creek and Butte
Creek sites.
-No additional sites were eliminated for failing to meet the energy
contribution criteria. The remaining sites upstream from Vee, i.e.,
Maclaren and Denali, were retained to insure that further study be
directed toward determining the need and viability of providing flow
regulation in the headwaters of the Susitna.
8.4 -Engineering Layouts
In order to obtain a uniform and reliable data base for studying the
seven sites remaining, it was necessary to develop engineering layouts
and reevaluate the costs. In addition, staged developments at several
of the 1 arger dams were studied.
The basic objective of these layout studies was to establish a uniform
and consistent development cost for each site. These layouts are con-
sequently conceptual in nature and do not necessarily represent optimum
project arrangements at the sites. Also, because of the 1 ack of geo-
technical information at several of the sites, judgmental decisions had
to be made on the appropriate foundation and abutment treatment. The
accuracy of cost estimates made in these studies is of the order of
plus or minus 30 percent.
(a) Design Assumptions
In order to maximize standardization of the layouts, a set of
basic design assumptions was developed. These assumptions covered
geotechnical, hydrologic, hydraulic, civil, mechanical, and elec-
trical considerations and were used as guidelines to determine the
type and size of the various components within the overall project
1 ayouts. As stated previously, other than at Watana, Devi 1 Can-
yon, and Denali, little information regarding site conditions was
available. Broad assumptions were made on the basis of the lim-
ited data, and those assumptions and the interpretation of data
have been conservative.
It was assumed that the relative cost differences between rockfill
and concrete dams at the sites would either be marginal or greatly
in favor of the rockfi 11. The more detai 1 ed studies carried out
8-3 Iii
subsequently for the Watana and Devil Canyon sites support this
assumption. Therefore, a rockfill dam has been assumed at all
developments in order to eliminate different cost discrepancies
that might result from a consideration of dam-fill unit costs com-
pa~ed to concrete unit costs at alternative sites.
(b) General Arrangements
A brief description of the general arrangements developed for the
various sites is given below. Plates 8.1 to 8.7 illustrate the
layout details. Table 8.2 summarizes the crest levels and dam
heights considered.
In laying out the developments, conservative arrangements have
been adopted, and whenever possible there has been a general stan-
dardization of the component structures.
(i) Devil Canyon (Plate 8.1)
The development at Devi 1 Canyon, located at the upper end
of the canyon at its narrowest point, consists of a rock-
fill dam, single spillway, power facilities incorporating
an underground powerhouse, and a tunnel diversion.
The rockfill dam will rise above the valley on the left
abutment and terminate in an adjoining saddle dam of sim-
ilar construction. The dam will be 675 feet above the low-
est foundation level with a crest elevation of 1470 and a
volume o~ 20 million cubic yards.
The spillway will be located on the right bank and will
consist of a gated overflow structure and a concrete-lined
chute linking the overflow structure with intermediate and
terminal stilling basins. Sufficient spillway capacity
will be provided to pass the Probable Maximum Flood safe-
1 y.
The power facilities will bn located on the right abutment.
The massive intake structure will be founded within the
rock at the end of a deep approach channel and will consist
of four integrated units, ?ach serving individual tunnel
penstocks. The powerhouse wi 11 house four 150-MW verti-
cally mounted Francis type turbines driving overhead 165
MVA umbrella type generator , .
As an alternative to the full power development in the
first phase of construction, a staged powerhouse alterna-
tive was also investigated. The dam would be completed to
its full height but with an initial plant installed capac-
ity in 300-MW range. '"•e camp 1 ete powerhouse would be con-
structed together with e1stocks and a tailrace tunnel for
the initial two 150-MW units, together with concrete foun-
dations for the future Jnits.
8-4
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( i i ) Watana (Plates 8.2 and 8.3)
For initial comparative study purposes, the dam at Watana
is assumed to be a rockfill structure located on a similar
alignment to that proposed in the previous COE studies. It
will be 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 sin-
gle quarry located on the left abutment. The dam will rise
880 feet from the lowest point on the foundation and have
an overall volume of approximately 63 million cubic yards
for a crest elevation of 2225.
The spillway will be located on the right bank and will be
s"imi 1 ar in concept to that at Devi 1 Canyon with an inter-
mediate and terminal stilling basin.
The power facilities located within the left abutment with
similar intake, underground powerhouse, and water passage
concepts to those at Devil Canyon will incorporate four
200-MW turbine/generator units giving a-total output of
800-MW.
-Staging Concepts
As an alternative to initial full development at Watana,
staging alternatives were investigated. These included
staging of both dam and powerhouse construction. Staging
of the powerhouse would be similar to that at Devil Can-
yon, with a Stage I installation of 400-MW and a further
400-MW in Stage II.
In order to study the alternative dam staging concept it
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 8.3.).
The powerhouse would be completely excavated to its final
size during the first stage. Three oversized 135-MW
units would be installed together with base concrete for
an additional unit. A low level control structure and
twin concrete-lined tunnels leading into a downstream
stilling basin would form the first stage spillway.
For the second stage, the dam would be completed to its
full height, the impervious core would be appropriately
raised and additional rockfill would be placed on the
downstream face. It is assumed that before construction
commences the top 40 feet of the first stage dam would be
removed to ensure the complete integrity of the impervi-
ous core for the raised dam. A second spillway centro 1
8-5
structure would be constructed at a higher level and
would incorporate a downstream chute leading to the Stage
I spillway structure. The original spillway tunnels
would be closed with concrete plugs. A new intake
structure would be constructed utilizing existing gates
and hoists, and new penstocks would be driven to connect
with the existing ones. The existing intake would be
sealed off. One additional 200 MW unit would be
installed and the required additional penstock and
ta-ilrace tunnel constructed. The existing 135-MW units
would be upgraded to 200 MW.
(iii) High Devil Canyon (Plate 8.4)
The development will be located between Devi 1 Canyon and
Watana. The 855 feet high rockfill dam will be similar in
design to Devil Canyon, containing an estimated 48 million
cubic yards of rockfill with a crest elevation of 1775.
The left bank spillway and the right bank powerhouse facil-
ities will also be similar in concept to Devil Canyon, with
an installed capacity of 800-MW.
Two stages of 400-MW were envisaged in each which would be
undertaken in the same manner as at Devil Canyon, with the
dam initially constructed to its full height.
(iv) Susitna III (Plate 8.5)
The development will involve a rockfill dam with an imper-
vious core approximately 670 feet high, a crest elevation
of 2360, and a volume of approximately 55 million cubic
yards. A concrete-lined spillway chute and a single
stilling basin and will be located on the right bank. A
powerhouse of 350-MW capacity wi 11 be located underground
and the two diversion tunnels on the left bank.
(v) Vee (Plate 8.6)
A 610 feet high rockfi 11 dam founded on bedrock with a
crest elevation of 2350 and total volume of 10 million
cubic yards was considered.
Since Vee is located further upstream than the other major
sites the flood flows are correspondingly lower, thus al-
lowing for a reduction in size of the spillway facilities.
A spillway utilizing a gated overflow structure, chute, and
flip bucket was adopted.
The power facilities will consist of a 400-MW underground
powerhouse located in the left bank with a tailrace outlet
well downstream of the main dam. A secondary rockfi ll dam
8-6
will also be required in this vicinity to seal off a low
point. Two diversion tunnels will be provided on the right
r-bank.
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(vi) Maclaren (Plate 8.7)
(vi i )
The development will consist of a 185 feet high earthfill
dam founded on pervious riverbed materials. The crest ele-
vation of the dam will be 2405. This reservoir will essen-
tially be used for regulating purposes. Diversion will
occur through three conduits located in an open cut on the
left bank and floods will be discharged via a side chute
spillway and stilling basin on the right bank.
Denali (Plate 8.7}
Denali is similar in concept to Maclaren. The dam will be
230 feet high, of earthfill construction, and will have a
crest elevation of 2555. As for IVlaclaren, no generating
capacity was to be included. A combined diversion and
spillway facility will be provided by twin concrete con-
duits founded in open cut excavation in the right bank and
discharging into a common stilling basin.
8.5 -Capital Cost
For purposes of initial comparisons of alternatives, construction quan-
tities were determined for items comprising the major works and struc-
tures at the sites. Where detail or data were not sufficient forcer-
tain work, quantity estimates have been made based on previous Acres 1
experience and the general knowledge of site conditions reported in the
1 iterature. 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 pre-
vious studies, and of rates used on similar works in Alaska and else-
where. Where applicable, adjustment factors based on geography, cli-
mate, manpower and accessibility were used. Technical publications
have also been reviewed for basic rates and escalation factors.
The total capital costs developed are shown in Tables 8.1 and 8.3. It
should be noted that the capital costs for Maclaren and Denali shown in
Table 8.1 have been adjusted to incorporate the costs of generation
plants with capacities of 55-MW and 60-MW, respectively.
8.6 -Formulation of Susitna Basin Development Plans
The results of the site screening process described in Section 8.3 in-
dicate 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:
8-7
-Devil Canyon;
-High Devil Canyon;
-Watana;
-Susitna III; or
-Vee.
Supplementary upstream flow regulation could be provided by structures
at:
-MacLaren; and
-Den ali .
A computer assisted screening process identified the plans that are
most economic as those of Devil Canyon/Watana or High Devil Canyon/Vee.
In addition to these two basic development plans, a tunnel scheme which
provides potential environmental advantages by replacing the De vi 1
Canyon dam with a long power tunnel and a development plan involving
Watana Dam was also introduced.
The criteria used at this stage of the process for selection of pre-
ferred Susitna Basin development plans are mainly economic (see Figure
8.1). Environmental considerations are incorporated into the further
assessment of the plans finally selected.
The results of the screening process are shown in Table 8.4. Because
of the simplifying assumptions that were made in the screening model,
the three best solutions from an economic point of view are included in
the table.
The most important conclusions that can be drawn are as follows:
-For energy requirements of up to 1,
Devil Canyon or the Watana sites ind
nomic energy. The difference betweer
around 10 percent, which is similar
pected from the screening model.
50 Gwh, the High Devil Canyon,
vidually provided the most eco-
~he costs shown on Table 8.4 is
o the accuracy that can be ex-
-For energy requirements of between 1, 750 and 3, 500 Gwh, the High
De vi 1 Canyon site is the most econorc: , .
-For energy requirements of between ~ 500 and 5,250 Gwh the combina-
tions of either ~Jatana and De':il Caii_)n or High Devil Canyon and Vee
are the most economic.
-The total energy production capability of the Watana/Devil Canyon
developments is considerably larger than that of the High Devil
Canyon/Vee alternative and is the onb plan capable of meeting energy
demands in the 6,000 Gwh range.
8-8
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-
(a) Tunnel Alternative
A scheme involving a long power tunnel could conceivably be used
to replace the Devil Canyon dam in the Watana/Oevi l Canyon deve 1-
opment plan. It could develop similar head for power generation
and may provide some environmental advantages by avoiding inunda-
tion 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
1,200 MW;
- A re-regulation dam if the intake works are located downstream
from Watana; and
-Arrangements for compensation flow in the bypassed river reach.
Four basic alternative schemes were developed and studied (see
Figure 8.4). All schemes assumed an initial Watana development
with full reservoir supply level at Elevation 2200 and the associ-
ated powerhouse with an installed capacity of 800 MW. Table 8.5
lists all the pertinent technical information. Table 8.6 lists
the power and energy yields for the four schemes.
Based on the foregoing economic information, Scheme 3 (Plates 8.8
and 8.9) produces the lowest cost energy by almost a factor of 2.
A review of the environmental impacts associated with the four
tunnel schemes indicates that Scheme 3 would have the least im-
pact, primarily because it offers the best opportunities for regu-
lating daily flows downstream from the project. Based on this
assessment, and because of its almost 2 to 1 economic advantage,
Scheme 3 was selected as the only scheme worth further study (see
Development Selection Report fr detailed analysis)·. The capital
cost estimate for Scheme 3 appears in Table 8.7. The estimates
also incorporate single and double tunnel options. For purposes
of these studies, the double tunnel option has been selected be-
cause of its superior reliability. It should also be recognized
that the cost estimates associated with the tunnels are probably
subject to more variation than those associated with the dam
schemes due to geotechnical uncertainties. In an attempt to com-
pensate for these uncertainties, economic sensitivity analyses us-
ing both higher and lower tunnel costs have been conducted.
8-9
(b) Selected Basin Development Plans
The essential objective of this step in the development selection
process is defined as the identification of those plans which ap-
pear to warrant further, more detailed evaluation. The results of
the final screening process indicate that the Watana/Devil Canyon
and the High Devil Canyon/Vee plans are clearly superior to all
other dam combinations. In addition, it was decided to study fur-
ther tunnel Scheme 3 as an alternative to the High Devil Canyon
dam and a plan combining a Watana/High Devil Canyon/Portage Creek
combination.
Associated with each of these plans are several options for staged
development. For this more detailed analysis of these basic
plans, a range of different aproaches to staging the developments
were considered. In order to keep the total options to a reason-
able number and also to maintain reasonably large staging steps
consistent with the total development size, staging of only the
two larger developments, i.e., Watana and High Devil Canyon, was
considered. The basic staging concepts adopted for these develop-
ments involved staging both dam and powerhouse construction, or
alternatively just staging powerhouse construction. Powerhouse
stages are considered in 400 MW increments.
Four
low.
High
Plan
basic plans and associated subplans are briefly described
Plan 1 involves the Watana-Devil Canyon sites, Plan 2
Devil Canyon-Vee sites, Plan 3 the Watana-tunnel concept,
4 the Watana-High Devil Canyon sites.
8.7-Evaluation of Basin Development Plans
be-
the
and
The overall objective of this step in the evaluation process was to
select the preferred basin development plan. A preliminary evaluation
of plans was initially undertaken to determine broad comparisons of the
available alternatives. This was followed by appropriate adjustments
to the plans and a more detailed evaluation and comparison.
In the process of initially evaluating the final four schemes, it be-
came apparent that there would be environmental problems associated
with allowing daily peaking operations from the most downstream reser-
voir in each of the plans described above. In order to avoid these po-
tential problems whiie 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 modlfied operational proced-
ures. Details of these modified plans. referred to as El to E4, are
listed in Table 8.8.
The plans listed in Table 8.8 were subjected to a more detailed analy-
sis as described in the following section.
8-10
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(a) Evaluation Criteria and Methodology
The approach to evaluating the various basin development plans
described above is twofold:
-For determining the optimum staging concept associated with each
basic plan (i.e. the optimum subplan), only economic criteria
are used and the least cost staging concept is adopted.
-For assessing which plan is the most appropriate, a more de-
tailed evaluation process incorporating economic, environmental,
social, and energy contribution aspects is taken into account.
Economic evaluation of any Susitna Basin development plan requires
that the impact of the plan on the cost of energy to the railbelt
area consumer be assessed on a systemwide basis. Si nee the con-
sumer is supplied by a large number of different generating sour-
ces, it is necessary to determine the total Rai lbelt system cost
in each case to compare the various Susitna Basin development op-
tions. The basic tool used to determine the system costs is the
optimum generation planning (OGP5) model described in Section 6.
The model simulates the performance of the system, incorporates
the hydroelectric development as specified, and adds thermal gen-
erating resources as necessary to meet the load growth and to sat-
isfy the reliability criteria. A summary of the input data to the
model and a discussion of the results follows.
( i ) Initial Economic Analyses
Table 8.9 lists the results of the first series of economic
analyses undertaken for the basic Susitna Basin development
plans listed in Table 8.8. The information provided in-
cludes the specified on-line dates for the various stages
of the p 1 ans, the OGP5 run index number, the tot a 1 in-
stalled capacity at year 2010 by category, and the total
system present-worth cost in 1980 for the period 1980 to
2040. The OGP5 model is run for the period 1980-2010.
Matching of the Susitna development to the load growth for
Plans E1, E2, and E3 is shown in Figures 8.5, 8.6, and 8.7,
respectively. After 2010, steady state conditions are
assumed and the then-existing generation mix and annual
costs for 2010 are applied to the years 2011 to 2040. This
extended period of time is necessary to ensure that the
hydroelectric options being studied, many of which only
come on-line around 2000, are simulated as operating for
periods approaching their economic 1 ives and that their
full impact on the cost of the generation system is taken
into account.
-Plan E1-Watana/Devil Canyon
Staging the dam at Watana (Plan El.2) is not as ·eco-
nomic as constructing it to its full height (Plans E1.1
8-11
and El. 3). The present worth advantage of not staging
the dam amounts to $180 million in 1980 dollars.
The results indicate that, with the level of analysis
performed, there is no discernible benefit in staging
construction of the Watana powerhouse (Plans El.1 and
El.3). However, Plan El.4 results indicates that,
should the powerhouse size at Watanabe restricted to
400 MW, the overall system present worth would in-
crease.
Additional runs performed for variations of Plan E1.3
indicated that system present worth would increase by
$1,110 million if the Devil Canyon dam was not con-
structed. A five year de 1 ay in construction of the
Watana dam would increase system present worth by $220
m i 11 ion.
-Plan E2-High Devil Canyon/Vee
The results for Plan E2.3 indicate that the system
present worth is $520 million more than Plan El.3.
Present worth increases also occur if the Vee dam stage
is not constructed. A reduction in present worth of
approximately $160 million is possible if the Chaka-
chamna hydroelectric project is constructed instead of
the Vee dam.
The results of Plan E;2.1 indicate that total system
present worth waul d i rcrease by $250 mi 11 ion if the
total capacity at High 'Jevil Canyon were limited to 400
MW.
-Plan E3 -Wata~a/Tunnel
The results for Plan E3.1 illustrate that the tunnel
scheme versus the Devi 1 C'l.nyon dam scheme (E1.3) adds ap-
proximately $680 millio1 to the total system present
worth cost. The availab,1ity of reliable geotechnical
data would undoubtedly have improved the accuracy of the
cost estimates for the tunnel alternative. For this rea-
son, a sensitivity ahalys~s was made as a check to deter-
mine the effect of halving the tunnel costs. This analy-
sis indicates that the tunnel scheme is still more costly
then constructing the Devil Canyon dam.
-Plan E4-Watana/High Devil Canyon/Portage Creek
The results indicate that system present worth associated
with Plan E4.1, excluding the Portage Creek site develop-
ment, are $200 mil: on more than the equivalent El.3
plan. If the Portage Creek development is included, the
present worth difference would be even greater.
8-12
r--
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I
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I
-1.
r
-
(b)
( i i ) Load Forecast Sensitivity Analyses
The plans with the lowest present-worth cost were subjected
to further sensitivity analyses to assess the economic im-
pacts of various load growths. These results are summar-
ized in Table 8.10.
The results for low load forecasts illustrate that the most
viable Susitna Basin development plan is the Watana-Devil
Canyon plan with a capacity of 800 MW which has a present
worth cost of $210 million less than its closest competi-
tor, the High Devil Canyon-Vee plan.
For the high load forecasts, the results indicate that the
Plan El. 3 has a present worth cost of $1040 mi 11 ion 1 ess
than E2.3.
Evaluation Criteria
The following criteria were used to evaluate the shortlisted basin
development plans. These criteria generally contain the require-
ments of the generic process with the exception that an additional
criterion, energy contribution, is added in order to ensure that
full consideration is given to the total basin energy potential
developed by the various plans.
( i) Economic
The parameter used is the total present-worth cost of the
total Rai lbelt generating system for the period 1980 to
2040 as listed in Table 8.10.
(ii) Environmental
A qualitative assessment of the environmental impact on the
ecological, cultural, and aesthetic resources is undertaken
for each plan. Emphasis is placed on identifying major
concerns so that these could be combined with the other
evaluation attributes in an overall assessment of the plan.
(iii) Social
This attribute includes determination of the potential non-
renewable resource displacement, the impact on the state
and local economy, and the risks and consequences of major
structural failures due to seismic events. Impacts on the
economy refer to the effects of an investment plan on eco-
nomic variables.
(iv) Energy Contribution
The parameter used is the tot a 1 amount of energy produced
from the specific development plan. An assessment of the
8-13
energy development foregone is also undertaken. The energy
loss that is inherent to the plan and cannot easily be re-
covered by subsequent staged developments is of greatest
concern.
(c) Results of Evaluation Process
The various attributes out 1 i ned above have been determined for
each plan and are summarized in Tables 8.11 through 8.18. Some of
the attributes are quantltative while others are qualitative.
Overall evaluation is based on a comparison of similar types of
attributes for each plan. In cases where the attributes associ-
ated with one plan all indicate equality or superiority with re-
spect to another plan, the decision as to the best plan is clear
cut. In other cases where some attributes indicate superiority
and others inferiority, differences are highlighted and trade-off
decisions are made to determine the preferred development plan.
In cases where these trade-offs have had to be made, they were
relatively straightforward, and the decision-making process can,
therefore, be regarded as effective and consistent. In addition,
these trade-offs are clearly identified so the recorder can inde-
pendently assess the judgment decisions made.
The overall evaluation process is conducted in a series of steps.
At each step, only two plans are compared. The superior plan is
then taken to the next step for evaluation against a third plan.
This process continues until the best plan has been selected.
(i) Devil Canyon Dam Versus Tunnel
The first step in the process involves the comparison of
the Watana-Devil Canyon dam plan (E1.3) and the Watana-
Tunnel plan (E3.1). Since Watana is common to both plans,
the evaluation is based on a comparison of the Devil Canyon
dam and Scheme 3 tunnel alternative.
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 8.11.
This information illustrates the breakdown of the total
system present worth cost in terms of capital investment,
fuel, and operation and maintenance costs.
-Economic Comparison
From an economic point of view, the Watana-Devi l Canyon
dam scheme is superior. As summarized in Tables 8.11 and
8.12, on a present worth basis the tunnel scheme is $680
million more expensive than the dam scheme. For a low
demand growth rate. this cost difference would be reduced
8-14
-
r
I
I"'""
I
!
,-
1
-I
s 1 i ght ly to $650 mi 11 ion. Even if the tunne 1 scheme
costs are halved, the total cost difference would still
amount to $380 million. As highlighted in Table 8.12,
consideration of the sensitivity of the basic economic
evaluation to potential changes in capital cost estimate,
the period of economic analysis, the discount rate, fuel
costs, fuel cost escalation, and economic plant life do
not change the basic economic superiority of the dam
scheme over the tunnel scheme.
-Environmental Comparison
The environmental comparison of the two schemes is sum-
marized in Table 8.13. Overall, the tunnel scheme is
judged to be superior because:
It offers the potential for enhancing anadromous fish
populations downstream of there-regulation dam due to
the more uniform flow distribution that will be
achieved in this reach;
It would inundate 13 miles less of resident fisheries
habitat in river and major tributaries;
. It has a lesser impact on wildlife habitat due to the
less extensive inundation of habitat by the re-regula-
t ion dam;
It has a lower potential for inundating archeological
sites due to the smaller reservoir involved; and
It would preserve much of the characteristics of the
De vi 1 Canyon gorge which is considered to be an aes-
thetic and recreational resource.
-Social Comparison
Table 8.14 summarizes the evaluation in terms of the
social criferi a of the two schemes. In terms of impact
on state and local economics and risks because of seismic
exposure, the two schemes are rated equal. However, the
dam scheme has, due to its higher energy yield, more po-
tential for displacing nonrenewable energy resources, and
therefore has a slight overall advantage in terms of the
social evaluation criteria.
-Energy Comparison
Table 8.15 summarizes the evaluation in terms of the en-
ergy contribution criteria. The results shown that the
dam scheme has a greater potential for energy production
and develops a larger portion of the basin•s potential.
8-15
The dam scheme is therefore judged to be superior from
the energy contribution standpoint.
-Overall Comparison
The overall evaluation of the two schemes is summarized
in Table 8.16. The estimated cost saving of $680 million
in favor of the dam scheme plus the additional energy
produced are 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 in-
volves an evaluation of the Watana-Devil Canyon (El.3) and
the High Devil Canyon-Vee (E2.3) development plans.
-Economic Comparison
In terms of the economic criteria (see Tables 8.11 and
8.12) the Watana-Devil Canyon plan is less costly by $520
million. Consideration of the sensitivity of this decis-
ion to potential changes in the various parameters con-
sidered (i.e. load forecast, discount rates, etc.) does
not change the basic superiority of the Watana-Devi 1
Canyon Plan.
-Environmental Comparison
The evaluation in terms of the environmental criteria is
summarized in Table 8.17. In assessing these plans, a
reach-by-reach comparison was made for the section of the
Susitna River between Portage Creek and the Tyone River.
The Watana-Devi 1 Canyon scheme would create more poten-
tial environmental impacts in the Watana Creek area.
However, it is judged that the potential environmental
impacts which would occur above the Vee Canyon dam with a
High De vi 1 Canyon-Vee a eve 1 opment are more severe in
overall comparison.
Of the seven environment a 1 factors considered in Tab 1 e
8.17 except for the increased loss of river valley. bird,
and black bear habitat, the Watana-Devi l Canyon develop-
ment plan is judged to be more environmentally acceptable
than the High Devil Canyon-Vee plan.
-Energy Comparison
The evaluation of t~? two plans in terms of energy con-
tribution criteria L Sdmmarized in Table 8.18. The
Watana-Devi 1 Canyon scheme is assessed to be superior
8-16
~.
-
-
-
-
because of its higher energy potential and the fact that
it develops a higher proportion of the basin•s energy
potential.
-Social Comparison
Table 8.14 summarizes the evaluation in terms of the
social criteria. As in the case of the dam versus tunnel
comparison, the Watana-Oevil Canyon plan is judged to
have a slight advantage over the High Devil Canyon-Vee
plan. This is because of its greater potential for dis-
placing nonrenewable resources.
-Overall Comparison
The overall evaluation is summarized in Table 8.19 and
indicates that the Watana-Oevil Canyon plans are gener-
ally superior for all the evaluation criteria.
8.8 -Preferred Susitna Basin Development Plan
One on one 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-Oevil Canyon plan was therefore selected as the pre-
ferred Susitna Basin development plan, as a basis for continua-
tion of more ~etailed design optimization and environmental
studies.
8-17
-
-
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I
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-
LIST OF REFERENCES
(1) Acres American Incorporated, Susitna Hydroelectric Project, Devel-
opment Selection Report, prepared for the Alaska Power Au-
thority, December 1981.
~ ~ -----1 1 l 1 ·--~ 1 l } -, c.---1 l <, __ l .,.-~, '} -·-~----1 J --~-, -1 1
TABLE 8.1: POTENTIAL HYDROELECTRIC DEVELOPMENT
Capital Average Economic 1
Dam Cost Installed Annual Cost of Source
Proposed Height Upstream $ million Capacity Energy Energy of
Site Type Ft. Regulation ( 1980) (MW) Gwh $/1000 kWh Data
Gold Creek 2 Fill 190 Yes 900 260 1' 140 37 USBR 1953
Olson
(Susitna II) Concrete 160 Yes 600 200 915 31 USBR 1953
KAISER 1974
CDE 1975
Devil Canyon Concrete 675 No 830 250 1,420 27 This Study
Yes 1,000 600 2,980 17 II
High Devil Canyon II
(Susitna I) Fill 855 No 1,500 800 3,540 21 II
Devil Creek 2 Fill Approx No
850
Watana Fill 880 No 1' 860 BOD 3,250 28 II
Susitna Ill Fill 670 No 1 '390 350 1,580 41 II
Vee Fill 610 No 1,060 400 1,370 37 II
Maclaren 2 Fill 185 No 530 4 55 180 124 II
Denali Fill 230 No 480 4 60 245 81 II
Butte Creek2 Fill Approx No 40 1303 USBR 1953
150
Tyone2 Fill Approx No 6 22 3 USBR 1953
60
Notes:
(1) Includes AFDC, Insurance, Amortization, and Operatlon and Maintenance Costs.
(2) No detailed engineering or energy studies undertaken as part of this study.
(3) These are approximate estimates and serve only to represent the potential of these two damsites in perspective.
(4) Include estimated costs of power generation facility.
TABLE 8.2: DAM CREST AND FULL SUPPLY LEVELS
Staged Full Dam Average Dam
Dam Supply Crest Tailwater Height 1
Site Construction Level -Ft. Level -Ft. Level -ft. ft.
!":'!''""'')
Gold Creek No 870 880 680 290
Olson No 1,020 1,030 810 310
Portage Creek No 1' 020 1,030 870 250 r-~7"':]
Devil Canyon -
wtermediate
height No 1,250 1' 270 890 465 ,-~
Devil Canyon -
full height No 1 '450 1,470 890 675
rr~
High Devil Canyon No 1 '610 1,630 1 ,030 710
No 1,750 1, 775 1, 030 855
Watana Yes 2,000 2,060 1,465 680
~.
Stage 2 2,200 2,225 1,465 880
Susitna III No 2,340 2,360 1,810 670
_rr.' -\
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 ,F'....,...
Notes:
(';-~"
( 1) To foundation level.
~:-
1 l
Devil 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) Power System 195
6) Spillway System 130
7) Roads and Bridges 45
B) Transmission Line 10
9) Camp Facilitles and Support 97
10) Miscellaneous 1 B
11) Mobilization & Preparation 30
Subtotal 757
Contingency tZU%J 152
l:.ng ineer ing and uwner 's
Administration (12%) 91
TOTAL 1000
Notes:
TABLE B.3: CAPITAL COST ESTIMATE SUMMARIES
SUSITNA BASIN DAM SCHEMES
COST IN $MILLION 19BD
High Devil Canyon Watana Susitna III
177 5 ft Crest 2225 ft Crest 2360 ft Crest
BOO MW BOO MW 330 MW
11 46 13
4B 71 88 -
432 536 39B
0 0 0
232 244 140
141 165 121
6B 96 70
10 26 40
140 160 130
B 8 B
47 57 45
1137 1409 1053
227 ZtlZ Zll
136 169 126
1500 1860 1390
(1) Inc~udes recreational facilities, buildings and grounds and permanent operating equipment.
-l
Vee Maclaren Denali
2350 ft Crest 2405 ft Crest 2250 ft Crest
400 MW No power No power
22 25 3B
37 11B 112
1B3 106 100
40 0 0
175 0 0
74 0 0
BO 57 14
49 0 0
100 53 50
B 5 5
35 15 14
803 379 333
161 76 6/
96 45 40
1060 500 440
Total Demand
Cap. Energy
Run MW GWh
1 400 1750
2 800 3500
3 1200 5250
4 1400 6150
TABLE 8.4: RESULTS Of SCREENING MODEL
O~t1mal Solut1on
Slte
Names
High
Devll
Canyon
H1gh
Devil
Canyon
Watana
Devil
Canyon
TOTAL
Watana
Dev1l
Canyon
Total
')
J
Max. Inst.
Water Cap.
Level MW
1580 400
1750 800
2110 700
1350 500
1200
2150 740
1450 660
1400
fust
Total
Cost Site
$ millior Names
885 Devll
Canyon
1500 Watana
DeVll
Canyon
TOTAL
1690 H1gh
Devil
Cany::m
800 Vee
2490 TOTAL
1770
N 0
1000
2770
Suboptimal Solution Second Suboptimal Solution
Max. In st. Total Max. Inst. Total
Water Cap. Cost Slte Water Cap. Cost
Level MW $ million Names Level MW $ milllon
1450 400 970 Watana 1950 400 980
1900 450 1130 Watana 2200 800 1860
1250 350 710
800 1840
1750 800 1500 High 1750 820 1500
Devll
Canyon
2350 400 1060 Susitnc: 2300 380 1260
III
1200 2560 TOTAL 1200 2760
A L T E R N A T I V E S 0 L U T I 0 N A V A I L A B L E
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TABLE 8.5: INFORMATION ON THE DEVIL CANYON DAM AND TUNNEL SCHEMES
Devil Canyon Tunnel Scheme
Item Dam 1 L )
Reservoir Area
(Acres) 7,500 320 0 3,900
River Miles
F loaded 31.6 2.0 0 15.8
Tunnel Length
(Miles) 0 27 29 13.5
Tunnel V~lume
(1000 Yd ) 0 11,976 12,863 3,732
Compensating Flow
Release ( cfs) 0 1,000 1,000 1, 000
Reservo1r Volume
(1000 Acre-feet) 1,100 9.5 --350
Dam He1ght
(feet) 625 75 --245
Typical Daily
Range of Discharge
From Dev1l Canyon 6,000 4,000 4,000 8,300
Powerhouse to to to to
(cfs) 13,000 14,000 14,000 8,900
Approximate
Maximum Daily
Fluctuations in
Reservoir (feet) 2 15 --4
Notes:
3 Estimated, above existing rock elevation.
£1_
0
0
29
5,131
1,000
--
--
3,900
to
4,200
--
Installed
Capacity (MW)
Staqe Watana Tunnel
STAGE 1:
Watana Dam BOO ---
STAGE 2:
Tunnel:
-Scheme 1 800 550
-Scheme ~z 70 1' 150
-Scheme 850 330
-Scheme 4 800 365
Notes:
TABLE 8.6: TUNNEL SCHEMES POWER OUTPUT
AND AVERAGE ANNUAL ENERGY
Tunnel
Increase 1 in Average Annual
Installed Capacity Energy
(MW) (Gwh)
------
550 2,050
420 4,750
380 2,240
365 2,490
(1) Increase over Watana, BOO MW development energy of 3,250 Gwh/yr.
(2) Includes power and energy produced at re-regulation dam.
1
Increase 1n
Average
Annual Energy ~-
(Gwh)
---
2,050
1,900
2,1BO
890
rw:-'
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TABLE 8. 7: CAPITAL COST ESTIMATE SUMMARIES FOR
SCHEME 3 TUNNEL ALTERNATIVE
COSTS IN $MILLION 1980
Item
Land and damages, reservoir clear1ng
DiverslOn works
Re-regulat1on dam
Power system
(a) Main tunnels
(b) Intake, powerhouse, tailrace
and switchyard
Secondary power stat1on
Splllway system
Roads and br1dges
Transmission lines
Camp fac lllt ies and support
Mlscellaneous
Mob1lizat1on and preparatlOn
TOTAL CONSTRUCTION COST
Contingencles (20%)
Eng1neer1ng, and Owner's Admlnistration
TOTAL PROJECT COST
Two 30 ft
d1a. tunnels
14
35
102
680
557
123
21
42
42
15
131
8
47
1,137
227
136
1,500
One 40 ft
d1a. tunnel
14
35
102
576
453
123
21
42
42
15
117
8
47
1 '015
203
122
1' 340
TABLE 8.8: SUSITNA ENVIRONMENTAL DEVELOPMENT PLANS
Stage/Incremental Data
Max.tmum
Capital Cost Earliest Reservoir Seasonal
$ Milllons On-ll~e Full Supply Draw-
Plan Stage Construction (1980 values) Level -ft down-ft Date
E1.1 1 Watana 2225 ft 800 MW
& Re-Regulation Dam 1960 1993 2200 150
2 Devil Canyon ~1470 ft
400 MW 900 1996 1450 100
TOTAL SYSTEM 1200 MW 2860
E1.2 1 Watana 2060 ft 400 MW 1570 1992 2000 100
2 Watana raise to
2225 ft 360 1995 2200 150
3 Watana add 400 MW
capacity &
Re-Rc ~.at ior. :am 23C 1995 2200 150 ···--·-
4 Dev 1l Canyon 1470 ft
400 MW 900 1996 1450 100
TOTAL SYSTEM 1200 MW 3060
E1 .3 1 Watana 2225 ft 400 MW 1740 1993 2200 150
2 Watana add 400 MW
capacity &
Re-Regulation Dam 250 1993 2200 150
3 Devil Canyon 1470 ft
400 MW 900 1996 1450 100
TOTAL SYSTEM 1200 MW 2890
Cumulative
System Data
Annual
Energy
Product10n
fIrm Avg
GWH GWH
2670 3250
5520 6070
1710 2110
2670 2990
2670 3250
5520 6070
2670 2990
2670 3250
5520 6070
1
)
Plant
Factor ., ,.
46
58
60
85
46
58
85
46
58
TABLE B.B (Cont'd)
Plan Stage
E1.4 1
2
E2.1 1
2
E2.2 1
2
3
E2.3 1
3
Construct 10n
Watana 2225 ft 400 MW
Devil Canyon 1470 ft
400 MW
TOTAL SYSTEM BOO MW
H1gh Dev1l Canyon
1775 ft BOO MW and
Re-Requlation Dam
Vee 2350 ft 400 MW
TOTAL SYSTEM 1200 MW
H1gh Devil Canyon
1630 ft 400 MW
High Devil Canyon
raise dam to 1775 ft
add 400 MW and
Re-Regulation Dam
Vee 2350 ft 400 MW
TOTAL SYSTEM 1200 MW
High Dev1l Canyon
1775 ft 400 MW
H1gh Dev1l Canyon add
400 MW capacity and
Re-Requlat1on Dam
Vee 2350 ft 400 MW
TOTAL SYSTEM 1200 MW
. · ...• 1
Capital Cost
$ M1llions
(1980 values)
1740
900
2640
1600
1060
2660
1140
600
1060
2800
I I
I 1390
I
240
1060
2690
Cumulative
Stage/Incremental Data System Data
Annual
Maximum I Energy
Ear llest Reservou Seasonal Production Plant
On-l1ne Full Suppl> Draw-F urn Avg Factor
Date 1 GWH GWH "' Level -ft down-ft '"
1993 2200 150 2670 2990 85
1996 1450 100 5190 5670 81
I I
19943 1750 150 2460 3400 49
1997 2330 150 3870 4910 47
1993 3 1610 100 1770 2020 58
1996 1750 150 2460 3400 49
1997 2330 150 3870 4910 47
I I I I
I I I I I
1994 3 1750 150 2400 i 2760 i 79
I I I I I
1995 1750 150 2460 3400 49
1997 2330 150 3870 4910 47
TABLE 8.8 (Cont'd)
Cumulat1ve
Stage/Incremental Data System Data
Annual
Max1mum Energy
Cap1tal Cost Ear hest Reservoir Seasonal Production Plant
$ Millions On-li~e Full Supply Draw-Firm Avg Factor
Plan Stag_E Canst ruct 1on (1980 values) Level -ft down-ft GWH GWH ., Date ,.
E2.4 1 High Devil Canyon
1775 ft 400 MW 1390 19943 1750 150 2400 2760 79
2 High Devil Canyon add
400 MW capacity and
Portage Creek Dam
150 ft 790 1995 1750 150 3170 4080 49
3 Vee 2350 ft 400 MW 1060 1997 2330 150 4430 5540 47
TOTAL SYSTEM 3240
E3.2 1 Watana 2225 ft 400 MW 1740 1993 2200 150 2670 2990 85
2 Watana add 400 MW
capacity and
Re-Regulation Dam 250 1994 2200 150 2670 3250 46
3 Watana add 50 MW
Tunnel Scheme 330 MW 1500 1995 1475 4 4890 5430 53
TOTAL SYSTEM 1180 MW 3490
E4. 1 1 Watana 2225 ft 400 MW 1740 19953 2200 150 2670 2990 85
2 Watana add 400 MW
capacity and
Re-Requlation Dam 250 1996 2200 150 2670 3250 46
3 High Dev1l Canyon
1470 ft 400 MW 860 1998 1450 100 4:J20 5280 50
4 Portage Creek 1030 ft
150 MW 650 2000 1020 50 5110 6000 51
TOTAL SYSTEM 1350 MW 3500
NOTES:
~Allow1ng for a 3 year overlap construction period between major dams.
(2) Plan 1.2 Stage 3 is less expensive than Plan 1.3 Stage 2 due to lower mobilizatwn costs.
(3) Assumes FERC license can be f1led by June 1984, i.e., 2 years later than for the Watana/Dev1l Canyon Plan 1.
1 J J )) J ~ ; J j ,:{ "'
-1 1 1 'l _,_,_ -1 ~------1 cl , __ 1
TABLE 8.9: RESULTS OF ECONOMIC ANALYSES OF SUSITNA PLANs(1)
~usitna Development Plan Inc. Installed Capac1ty _\MWJ by
Online Uates Cateqory in Z010
Plan Staqes OGP5 Run Thermal H~dro
No. 1 z ~ 4 Id. No. Coal Lias Dil Other Susitna
E1.1 1993 zooo ----LXE7 300 4Z6 0 144 1ZOO
E1.Z 1992 1995 1997 zooz L5Y9 zoo 501 0 144 1ZOO
E1.3 1993 1996 zooo --L8J9 300 4Z6 0 144 1ZOO
1993 1996 ----L7W7 500 651 0 144 BOO
1998 Z001 Z005 --LAD7 400 Z76 30 144 1ZOO
E1.4 1993 zooo ----LCK5 zoo 726 50 144 800
EZ. 1 1994 zooo -- --
LBZ5 400 651 60 144 800
EZ.3 1993 1996 zooo --L601 300 651 zo 144 1ZOO
1993 1996 ----LE07 500 651 30 144 800
EZ.3 1993 1996 zooo LEB3 300 726 zzo 144 1300
3.1 1993 1996 zooo --L607 zoo 651 30 144 1180
3.1S 1993 1996 zooo --L615 zoo 651 30 144 1180
E4. 1 1995 1996 1998 --LTZ5 zoo 576 30 144 1Z00
NOTES:
( 1) These studies were completed .In mid-1980 using ISERs 1980 energy demand forecasts.
(Z) Present worth in 1980 dollars of system costs from 1980 to Z040.
Total System
Installed
Capac1ty In
Z010-MW
Z070
Z045
Z070
Z095
Z050
1920
Z055
Z315
Z1Z5
Z690
ZZ05
ZZ05
Z150
' ·---) .-·---1 -----1 --, _____
l .. ---J
Total System
Present Remarks Pertaining to
Worth Cos2 the Sus1tna Basin
$ M.tllion Development Plan
5850
6030
5850 State 3, Devil Canyon Dam
6960 not canst ructed.
6070 Delayed lmplementation
schedule.
5890 Total development limited
to BOO MW.
66ZO High Devil Canyon limited
to 400 MW.
6370 Stage 3, Vee Dam, not
6720 constructed.
6Z10 Vee dam replaced by
Chakachamna dam.
6530
6Z30 Cap1tal cost of tunnel
reduced by 50 percent.
6050 Stage 4 not constructed.
TABLE 8.10: RESULTS OF ECONOMIC ANALYSES OF SUSITNA PLANS -LOW AND HIGH LOAD FORECAST
Susitna Development Plan Inc. Installed Capacity (MW) by Total System Total System
Onl1ne lJates Category in 2010 Installed Present Remarks Pertaining to
Plan Staqes OGP5 Run Thermal H dro Capacity In Worth Cost the Susitna Basin
No. 1 r 2 3 4 I d. No. Coal Gas Oil Other Susltna 2010-MW $ Million Development Plan
LOW LOAD FORECAST
E1.4 1993 2002 ----LC07 0 351 40 144 800 1335 4350 Watana llmited to 400 MW.
1"""993 ------LBK7 200 501 80 144 400 1.525 4940 Stage 2, Devll Canyon Dam,
not constructed.
E2.1 1993 2002 ----LG09 100 426 30 144 800 1500 4560 H1gh Dev1l Canyon llmited
to 400 MW.
1993 ------LBU1 400 501 0 144 400 1445 4850 Stage 2, Vee Dam, not
constructed.
3 .1S 1993 1996 2000 --L613 0 576 20 144 780 1520 4730 Capital cost of tunnel
reduced by 50 percent.
3.2 1993 2002 -- --
L609 0 576 20 144 780 1520 5000 Stage 2, 400 MW addition
to Watana, not constructed.
3. 15
I
19931 1996 2000 --L613 0 576 20 144 780 1520 4730 Capital cost of tunnel
'"
reduced by 50 percent.
3.2 ' 1993 2002 ----L609 0 ">76 20 144 780 1520 5000 Stage 2, 400 MW addition
' ' to Watana, not constructed. -__ ( _____ ,
HIGH LOAD FORECAST
E1.3 1993 1996 2000 --LA73 1000 951 0 144 1200 3295 10680
Modi fled
E1.3 1993 1996 2000 2005 LBV7 800 651 60 144 1700 3355 10050 Chakachamna hydroelectric
generatmg station (480 MW)
brought online as a fourth
staqe.
E2.3 1993 1996 2000 --LBV3 1300 951 90 144 1200 3685 11720
Modified
E2. 3 1993 1996 2000 2003 LBY1 1000 876 10 144 1700 3730 11040 Chakachamna hydroelectric
generating station (480 MW)
brought onl1ne as a fourth
staqe.
J 3 J
-
-I
f
!
-i r
-I
-
-
Parameter
Capital Investment
Fuel
Operation and Maintenance
TOTAL:
TABLE 8.11: BASIC ECONOMIC DATA FOR EVALUATION OF PLANS
Total Present Worth Cost for 1981 -2040
Period $ Million 0~ Total)
Generation Plan Generation Plan Generation Plan
With High Devil With Watana -With Watana -All Thermal
Canyon -Vee Devil Canyon Dam Tunnel Generation Plan
2800 (44) 2740 (47) 3170 (49) 2520 (31)
3220 (50) 2780 (4 7) 3020 (46) 5240 (64)
350 (6) 330 (6) 340 (5) 370 (5)
6370 (1 00) 5850 (100) 6530 (1 DO) 8130 (100)
TABLE 8.12: ECONOMIC EVALUATION OF DEVIL CANYON DAM AND TUNNEL SCHEMES AND WATANA/DEVIL CANYON AND HIGH DEVIL CANYON/VEE PLANS
Present worth of Net Benefit ($ million) of total generation
system costs for the:
Devil Canyon Dam over Watana/Devil Canyon Dams over
the Tunnel Scheme the High Devil Canyon/Vee Dams Remarks
ECONOMIC EVALUATION: Economic ranking: Devil Canyon
dam scheme 1s superior to Tunnel
-Base Case 680 520 scheme. Watana/Dev .il Canyon dam
plan Is superior to the High
Devil Canyon dam/Vee dam plan.
SENSITIVITY ANALYSES:
-Load Growth Low 650 210 The net benef1t of the Watana/
High N.A. 1 Ol~O Devil Canyon plan remains positiv e
for the range of load forecasts
considered. No change in ranking
-Capital Cost Estimate Higher uncertainty assoc-Higher uncertainty associated with Higher cost uncertainties associ-
iated with tunnel scheme. H.D.C./Vee plan. ated with higher cost schemes/
plans. Cost uncertainty there-
fore does not affect economic
rankinq.
-Period of Economic PerIod shortened to Shorter period of evaluation
Analysis (1980 -2010) 230 160 decreases economic differences.
Ranki~g remains unchanqed.
-Discount Rate SO' '" 8"' '" (interpolated)
9%
-Fuel Cost 80% basic fuel cost As both the capital and fuel costs associated with the tunnel Ranking remains unchanged.
scheme and H.D.C./Vee Plan are higher than for Wat ana/Devil
-Fuel Cost Escalation 0"' '" fuel escalation Canyon plan any changes to these parameters cannot reduce the
0"' '" coal escalation Devil Canyon or Watana/Devil Canyon net benefit to below zero.
-Economic Thermal Plant sm~ extension
Life 0% extension
_)
.... J .· "1 ---1 1 1 --l 1
TABLE 8.13: ENVIRONMENTAL EVALUATION OF D£VlL CANYON DAM AND TUNNEL SCHEME
Environmental
Attribute
Ecological:
-Downstream Fisheries
and Wildlife
Resident Fisheries:
Wildlife;
Land Use:
Concerns
Effects resulting
from changes in
water quantity and
quality.
No significant differ-
ence between achemes
regarding effects down-
stream of Devil Canyon.
Difference in reach
between D=:vil Canyon
dam and tunnel re-
regulation dam.
Loss of resident Minimal differences
fisheries habitat. between schemes.
Loss of wildlife Minimal differences
habitat. between schemes.
Inundation of Potential differences
archeological sites. between schemes.
Inundation of Devil Significant difference
Canyon. between sc:hemes.
Identification
of difference
With the tunne 1 scheme con-
trolled flaws between regula-
tion dam and downstream power-
house offers potential for
anadromous fisheries enhance-
ment in this 11 mile reach of
the river.
D=:vil Canyon dam would inundate
27 miles of the Susitna Ri..,...er
and approximately 2 miles of
1:2vil Creek. The tunnel scheme
would inundate 16 miles of the
Susitna River.
The most sensitive wildlife ha-
bitat in this reach is upstream
of the tunnel re-regulation dam,
where there is no significant
difference between the schemes.
The Devil Canyon dam scheme in
addition inundates the river
"alley between the two dam
sites resulting in a moderate
increase in impacts to wildlife.
D.Je to the larger area inun-
dated the probability of inun-
dating archeologic:al sites is
increased.
The IA::'v'il Canyon is considered
a unique resource, 80 percent
of which would be inundated by
the [evil Canyon dam scheme.
This would result in a loss of
both an aesthetic value plus
the potential for white water
recreation.
OVERALL EVALUATION: The tunnel scheme has overall a lower impact on the en'v'ironment.
Appraisal Judgement
Not a factor in evaluation of
scheme.
If Fisheries enhancement oppor-
tunity can be realized the tun-
nel scheme offers a positive
mitigation measure not available
with the Devil Canyon dam
scheme. This opportunity is
considered moderate and fa'v'ors
the tunnel scheme. Hollllever t
there are no current plans for
such enhancement and feasibil-
ity is uncertain.. Potential
value is therefore not signi-
ficant relative to additional
cost of tunnel.
Loss of habitat with dam scheme is
less than 5% of total for Susitna
main stem. This reach of river is
therefore not considered to be
highly significant for resident
fisheries and thus the difference
between the schemes is minor and
favors the tunnel scheme.
Moderate wildlife populations of
moose, black bear, weasel, fox,
wol'v'erine, other small mammals
and songbirds and some riparian
cliff habitat for ra'v'ens and
raptors, in 11 miles of river,
would be lost "w'ith the dam scheme.
Thus, the difference in loss of
wildlife habitat is considered
moderate and fa .... ors the tunnel
scheme.
Significant arc:heologic:al
sites, if identified, c:an proba-
bly be exc:avated. Additional
costs could range from several
hundreds to hundreds of thousands
of dollars, but are still consider-
ably less than the additional cost
of the tunnel scheme. This conc:ern
is not considered a factor in scheme
e"aluation.
The aesthetic: and to some extent
the recreational losses associ-
ated with the development of the
Devil Canyon dam is the main
aspect favoring the tunne 1 scheme.
However, current recreational uses
of O:!vil Canyon are low due to
limited access. Future possibilites
include major recreational develop-
ment with construction of restau-
rantst marinas, etc:. Under such
c:onditions, neither scheme would be
more favorable.
l
Social
Aspect
Potential
non-renewable
resource
displacement
Impact on
state economy
Impact on
local economy
Seismic
exposure
Overall
Evaluation
TABLE 8.14: SOCIAL EVALUATION OF SUSITNA BASIN DEVELOPMENT SCHEMES/PLANS
Parameter
Million tons
Beluga coal
over 50 years
J
Risk of major
structural
failure
Potential
impact of
failure on
human life.
Tunnel
Scheme
Devil Canyon
Dam Scheme
High Devil Canyon/
Vee Plan
Wat ana/Devil
Canyon Plan
80 110 170 210
All projects would have s1milar impacts on the state and
local economy.
All projects designed to s1milar 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 Dev1l Canyon/Vee plan.
l
Remarks
Devil Canyon dam scheme
potential higher than
tunnel scheme. Watana/
Dev1l Canyon plan h1gher
than H1gh Devil Canyon/
Vee plan.
Essentially no difference
between plans/schemes.
l
r
~
I
i
r
I
I
'
r-
1
r
-I
r
l
TABLE 8.15: ENERGY CONTRIBUTION EVALUATION OF THE DEVIL
CANYON DAM AND TUNNEL SCHEMES
Parameter
Total Energy Production
Capability
Annual Average Energy GWH
Firm Annual Energy GWH
% Basin P~tential
Developed
Enerly Potential Not
Deve oped GWH
Notes:
Dam
2850
2590
43
60
Tunnel
2240
2050
32
380
Remarks
Devil Canyon dam annually
develops 610 GWH and 540
GWH more average and firm
energy respectively than
the Tunnel scheme.
Devil Canyon schemes
develops more of the
basin potential.
As currently envisaged,
the Devil Canyon dam does
not develop 15 ft of the
gross head between the
Watana site and the Devil
Canyon reservsoir. The
tunnel scheme incorporates
additional friction losses
in tunnels. Also the
compensation flow released
from re~regulation dam is
not used in conjunction
with head between
re-regulation dam and Devil
Can on.
(1) Based on annual average energy. Full potential based on USBR four
dam scheme.
TABLE 8.16: OVERALL EVALUATION OF TUNNEL SCHEME AND DEVIL CANYON DAM SCHEME
ATTRIBUTE
Economic
Energy
Contribution
Environmental
Social
Overall
Evaluation
SUPERIOR PLAN
Devil Canyon Dam
Devil Canyon Dam
Tunnel
Devil Canyon Dam (Marginal)
Devil Canyon dam scheme is superior
Tradeoffs made:
The significant energy and economic
advantage of dam scheme are judged to
outweigh the reduced environmental
impact associated with the tunnel
scheme.
~~~1
Environmental Attribute
2) WildliFe
a) Moose
b) Caribou
c) Furbearers
d) Birds and .Bears
1 1 l
TABLE 8.17: ENVIRONMENTAL EVALUATION OF WATANA/DEVlL CANYON AND HIGH DEVIL CANYON/VEE DEVELOPMENT PLANS
Plan Comparison
No signific:ant difference in effects on downstream
anadromous fisheries.
HDC/V 'i'Would inundate approximately 95 miles of the
Susitna River and 28 miles of tributary streams, in-
cluding the Tyone River.
W/DC would inundate approximately 84 miles of the
Susitna River and 24 miles of tributary streams,
includin Watana Creek.
Appraisal Judgement
tAle to the avoidance of the T yone River,
lesser inundation of resident fisheries
habitat and no signi fi~ant difference in the
effects on anadromous fisheries, the W/OC plan
is judged to have less impact.
HOC/V would inundate 123 miles of critical winter river OJe to the lower potential for direct impact
bottom habitat. on moose populations within the Susitna, the
W/OC plan is judged superior.
W/OC would inundate 108 miles of this river bottom
habitat.
HOC/V would inundate a large area upstream of Vee
utilized by three sub-populations of moose that range
in the northeast section of the basin.
W/DC would inundate the Watana Creek area utilized by
moose. The condition of this sub-population of moose
~Bdb~h~e~~~~~~~g?f the habitat they are using appears
The increased length of river flooded, especially up-
stream from the Vee dam site, would result in the
HDC/V plan creating a greater potential division of
the Nelchina herd 1 s range. In addition, an increase
in range would be directly inundated by the Vee res-
ervoir.
DJe to the potential for a greater impact on
the Nelchina caribou herd, the HOC/V scheme
is considered inferior.
The area flooded by the Vee reservoir is considered Due to the lesser potential for impact on fur-
important to some key furbearers, particularly red fox. bearers the W/OC is judged to be superior.
This area is judged to be more important than the
Watana Creek area that· would be inundated by the W/DC
plan.
Forest habitat, important for birds and black bears, The HOC/V plan is judged superior.
exist along the valley slopes. The loss of this habi-
tat would be greater with the W/OC plan.
There is a high potential for discovery of archeologi-The W/OC plan is judged to have a lower po-
cal sites in the easterly region of the Upper Susitna tential effect on archeological sites.
Basin. The HOC/V plan has a greater potential of
affecting these sites. For other reaches of the river
the difference between plans is considered minimal.
----1 --~1
J
TABLE 8.17 (Cont'd)
Environmental Attribute
Aesthetic/
~
Plan Comparison
With either scheme, the aesthetic quality of both
Devil Canyon and Vee Canyon .would be ilfl'Bired. The
HOC/V plan would also inundate Tsusena Falls.
IA.Je to constt"uction at Vee Dam site and the size of
the Vee Reservoir, the HDC/V plan would inherently
create access to more wildet"ness area than would the
W/OC plan.
Appraisal Judgement
Both plans impact the valley aesthetics.
difference is considered minima 1.
The
As it is easier to extend access than to
limit it, inherent access requirements were
considered detrimental and the W/DC plan is
judged superior. The ecological sensitivity
of the area opened by the HDC/V plan rein-
forces this judgement.
OVERALL EVALUATION: The W/OC plan is judged to be superior to the HDC/V plan.
(The lo.,.er ifl'l'act on birds and bears associated with HDC/V plan is considered to be outweighed by all
the other impacts \lrhich favor the W/DC plan.)
W = Watana Dam
DC = Devil Canyon Dam
HOC = High Devil Canyon Dam
V = Vee Dam
'I J
i L
r
r""'
r
!
r
'
-
TABLE 8.18: ENERGY CONTRIBUTION EVALUATION OF THE WATANA/DEVIL CANYON
AND HIGH DEVIL CANYON/VEE PLANS
Parameter
Total Energy Production
Capability
Annual Average Energy GWH
Firm Annual Energy GWH
% Basin Potential
Developed (1)
Eneriy Potential Not
Deve oped GWH (2)
Notes:
Watana/
Devil Canyon
6070
5520
91
60
High Devil
Canyon/Vee
4910
3870
81
650
Remarks
Watana/Devil Canyon
plan annually devel-
ops 1160 GWH and
1650 GWH more average
and firm energy re-
pectively than the
High Dev1l Canyon/Vee
Plan.
Watana/DeVll Canyon
plan develops more of
the basin potential
As currently con-
ceived, the Watana/-
Devil Canyon Plan
does not develop 15
ft of the gross head
between the Watana
s1te and the Devil
Canyon reservoir.
The High Devil
Canyon/Vee Plan does
not develop 175 ft
of the gross head
between Vee site and
High Devil reservoir.
(1) Based on annual average energy. Full potential based on USBR four
dan schemes.
(2) Includes losses due to unutilized head.
TABLE 8.19: OVERALL EVALUATION Of THE HIGH DEVIL CANYON/VEE AND
WATANA/DEVIL CANYON DAM PLANS
ATTRIBUTE SUPERIOR PLAN
Economic Watana/Devil Canyon
Energy
Contribution
Environmental
Social
Overall
Evaluation
Watana/Dev~l Canyon
Watana/Devil Canyon
Watana/Devil Canyon (Marginal)
Plan with Watana/Devil Canyon is
superior
Tradeoffs made: None
"'1 ~· -1 ----1 -· J ,;--~ --
PREVIOUS
STUDIES AND
FIELD
RECONNAISSANCE
12DAM
SITES
GOLD CREEK
DEVIL CANYON
HIGH DEVIL CANYON
DEVIL CREEK
WATANA
SUSITNA ill
VEE
MACLAREN
.DENALI
BUTTE CREEK
TYONE
'· 1 ··---] <<-.. --.. ~ "--·~-] c•"-····l ·-1 1 ·--~-,
SCREEN
ENGINEERING
LAYOUT AND
COST STUDIES
7DAM
SITES
COMPUTER MODELS
TO DETERMINE
LEAST COST DAM
COMBINATIONS
3 BASIC
DEVELOP-
MENT
PLANS
1-C-=--R~IT.:....:E~R~IA ____ --1 DEVIL CANYON
ECONOMICS HIGH DEVIL
OBJECTIVE
ECONOMIC
WATANA I DEVIL
CANYON
CANYON ENVIRONMENTAL WATANA
ALTERNATIVE SUSITNA m
SITES
ENERGY VEE
CONTRIBUTION MACLAREN
'-----------'DENALI
.___ _____ _, HIGH DEVIL
CANYON/VEE
HIGH DEVIL
CANYON I WATANA
ADDITIONAL SITES
PORTAGE CREEK
J .. , ___ 1
J l
DATA ON DIFFERENT
THERMAL GENERATING
SOURCE~S~------~--~
CRITERIA
COMPUTER MODELS
TO EVALUATE
-POWER AND
ENERGY YIELDS
-SYSTEMWIDE
ECONOMICS
ECONOMIC
ENVIRONMENTAL
SOCIAL
WATANAIDEVIL
CANYON
PLUS THERMAL
ENERGY
CONTRIBUTION
LEGEND
DIS HIGH DEVIL CANYON
DIS WATANA
~STEP NUMBER IN
STANDARD PROCESS
(APPENDIX A)
SUSITNA BASIN PLAN FORMULATION AND SELECTION PROCESS
FIGURE 8. I lAoornl
PORTAGE CR.
-I
100
~ ~
C( C( u C[ 1~!51-z
z !:: ~~~ li C[ en IU u .... 20!50l ;:::) 1&.1
(I) i (I) >
C( l: ...J 22001
u, <D > t LIJ ...J :2: 0 17!50 1
. !I> a:: (I) ~ ~ dl r--f4!50
1
...J I j _._.........--200
g870' 1000 1
1020
!500 1
120 140 160 180
RIVER MILES____..
OSHETNA RIVER
....---------1 2000 I
____ _,.., Tj-TYONE RIVER
Ft----..... -~. 2oool
~,,._ACLAREN RIVER
~' 2200'
I I z I '~
I I ~ I ~ IU _I I I ....
I ....
I u z li I C( ~
~ 23601 I . ~ 2!53!5 ----.Z59f54' I
L2300'
220 240 260 280
3 oool
2 !500 I
2 ooo'
I !500 1
PROFILE THROUGH ALTERNATIVE SITES
FIGURE 8.2
---, , ___ ") -~,
GOLD
CREEK
----1 -
OLSON
-------, 1
DEVIL
CANYON
GOLD CREEK
OLSON
DEVIL CANYON
HIGH DEVIL CANYON
DEVIL CREEK
LEGEND
COMPATIBLE ALTERNATIVES
D
MUTUALLY EXCLUSIVE ALTERNATIVES
---J
HIGH
DEVIL
CANYON
WATANA
"---~-)
DEVIL
CREEK
SUSITNA m
"1 ,---J ' ---"1 ------, -------, --1 -------, -----~"1
WATANA SUSITNA :VEE MACLAREN DENALI
VEE
MACLAREN
DENALI
BUTTE CREEK
TYONE
MUTUALLY EXCLUSIVE DEVELOPMENT ALTERNATIVES
----1
BUTTE
CREEK
---
TYONE
fiGURE8.3 m
1
r
r
r
!"""
I
2200 FT. WATANA 800 MW
--'--2 MILES
2 TUNNELS
3 8 FT. D lAME TER
800 MW-70 MW
2 TUNNELS
~8 FT. DIAMETER
800 MW-850 MW
15.8 MILES I
,---j...!._-'-· 14 7 5 FT.
DAM
DEVIL CANYON
550 MW
1150 MW
---RE-REGULATION DAM
30 MW
300 MW
30 FT. DIAMETER
800 MW
2 TUNNELS 3155 MW
24 FT. DIAMETER
SCHEMATIC REPRESENTATION
OF CONCEPTUAL TUNNEL SCHEMES
TUNNEL
SCHEME
#
I.
2.
3.
4.
FIGURE 8.4
3
r-
3: ,..... ~
2 I 0
0
0
1->-
1-
(.)
r' ~ I
<( ! (.)
1-,
~
0
r-
10
r
!
!"""
i 8 f
""""
:I: -3: 6 (!)
0
0
0 ,...,
>-
(!)
a:: 4 w ,..... z w
r
'
2
715
103
1980
1980
1990
LEGEND:
D HYDROELECTRIC
l\\}(J COAL FIRED THERMAL
[ZJ GAS FIRED THERMAL
2000
• OIL FIRED THERMAL( NOT SHOWN ON ENE~GY DIAGRAM
NOTE : RESULTS OBTAINED FROM
OGPS RUN L8J9
1990
TIME
DEVIL C.ANYON
(400 MW)
WATANA-1 (400 MW)
EXISTING 8 COMMHTED
2000
GENERATION SCENARIO WITH SUSITNA PLAN E 1.3
-MEDIUM LOAD FORECAST-
FIGURE
2010
2010
,-.
I
r
r-
1
t
3
10
8
I
~6 (!)
0
0
0
>-(!)
·ffi 4
z w
2
LEGEND:
D HYDROELECTRIC
[J}JJ COAL FIRED THERMAL
[Z] GAS FIRED THERMAL
-OIL FIRED THERMAL( NOT SHOWN ON ENERGY DIAGRAM
NOTE: RESULTS OBTAINED FROM
OGPS RUN L60 I
VEE(400 MW)
HIGH DEVIL CANYON-I (400 MW)
EXISTING AND COMMITTED
0~--~----------------------------------------------------------------~ 1980 1990 2000
TIME
GENERATION SCENARIO WITH SUSITNA PLAN E 2.3
-MEDIUM LOAD FORECAST-
FIGURE
2010
8.6.
,....
'
-
r
r""
,...
"""" '
-
r
-
r
3
3:
~ 2
0
0
0
>-1-
u
<( a..
<(
u
0
10
8
:I:
3: 6
(!)
0
0
Q
>-
(!)
~ 4 z w
2
715
103
1980
1980
1990
LEGEND'
D HYDROELECTRIC
ktt:fJ COAL FIRED THERMAL
~ GAS FIRED THERMAL
2000
• OIL fiRED THERMAL (NOT SHOWN ON ENERGY DIAGR
NOTE: RESULTS OBTAINED FROM
OGPS RUN L607
1990
TIME
TUNNEL ( 380 MW)
WATANA -I ( 400 MW)
2000
GENERATION SCENARIO WITH SUSITNA PLAN E3.1
-MEDIUM LOAD FORECAST-
FIGURE 8.7
2010
2010
~·~·-1
1!500
1-1300 ..
~
!! 1200
GENERAL ARRANGEMENT
SCALE: A
.~ .. ~-}
rCREST EL. 1470 j AT <t OFOAM
EXCAVATION FOR CORE~\ _,/ ./ }-GROUT GALLERIES ~ 1100
~ 1000 r-~----~------'-'-':."..-'c-·----'?Ly"/,~_51~~=_!~ ____ _
-------~'\.\~ Jj: !L ~ 900
800
~~'£.c ____ JC
LONGITUDINAL SECTION THRU ft. OF DAM
SCALE: 8
SECTION A-A
SCALE: B
~
"' ~
;.,
!'i
I= ~
1600
11500
1400
1300
!i 1200 ~ 1100
iii
1000
900
800
l
It! DO
1400
1300
1200
1100
1000
900
800
·~----EL 146-z"'----.nnr· .
m 111
SECTION THRU DAM
SCALE: B
....-EXISTING GR.c.OU.c..N.co_s.~U~R_FA~C~E ______ _
-·~-----
-·-------c-ON-C-RE_T_E_P_L_UG--;f-/s_T-i-EE~5 ~rNER L '-MANIFOLD
; _._~ GATE SHAFT
000
1!500
~ 1400
"' "' ... 1300
!!
z 1200
0 ;:: 1100
§ 1000
"'
900
800
SCALE A
SCALE B
500 1000
STATIONING IN FEET
POWER FACILITIES PROFILE
SCA\..E! B
SPILLWAY CONTROL STRUCTURE
!5-4dX40' WHEEL MOUNTED GATES
000 1000
SPILLWAY PROFILE
SCALE: B
1!500 2000
EXISTING GROUND SURF.f.CE ON
RIGHT SIDE OF SPIUWAY -
1000
STATIONING IN FEET
1000
~~~4~0~0-iiSOO~ FEET
e~~2i.ii0ii;O iiiiiiii4iii00 FEET
~~~~~~~I--A-:;LAc.-ooS=K=Acc:P=O""W:;;-;ER=AU::-:T=::H:-::O:o:RI:--TY---1
SUSITNA HYDROELECTRIC PROJECT
THIS DRAWING ILLUSTRATES A
PRELIMINARY CONCEPTUAL PROJECT LAYOUT
PREPARED FOR COMPARISON OF
ALTERNATIVE SITE DEVELOPMENTS ONLY
DEVIL CANYON
HYDRO DEVELOPMENT
FILL DAM
PLATE
8.1
,"---1
2300
2100
~2000
~ 1900
z
;1eoo
0
5t700
~
iif1600
1000
1400
'_-~-·--,
2300
2200
2100
2000
1900
~ 1800
1&, 1700
z
z 1600
0 s 1!500
~ 1400
1300
----) ·-----, ~---1 .-----1 J
SPILLWAY 220o
~23oo----
/~--.
2000
~ 1900
II. IBOO
z
GENERAL ARRANGEMENT ~ 1700
;::
0+00
SCALE• A
!itOO 10+00
STATIONING IN FEET
SPILLWAY PROFILE
SCALE• B
!S+OO
/CREST EL.222!5 AT CENTERLINE
OF DAM
~ 1600
~ IMO
1400
-!5-f-00
20+0D
LONGITUDINAL SECTION THRU CENTERLINE OF OAM
SCALE • B
-----1 -~~-,
2300
2200
2100
2000
~ 1900
;!; 1800
z
0 1700 ~ 1600 ~
CONCRETE PLUG
0-tQQ
EXISTING ROCK
LEVEL
----~,
AJMtiRf
.--~·) c------1 -----1
SECTION THRU DAM
,,
" ,,
" " :~CABLE SHAFTS
II
SCALE•B
:: /-TRANSFORMER AND DRAFT
11 TUBE GATE GALLERY
"
1 l
2-23' DIA. CONCRETE LINED TUNNELS
•.oo 10-f-00 l~t{)Q 20+00
STATIONING IN FEET
POWER FACILITIES PROFILE
-~--
SECTION A-A
SCALE•C
--:::
SCALE• B
\EX~ STING GROUND
----
ROCK ANCHORS
THIS DRAWING ILLUSTRATES A
PRELIMINARY CONCEPTUAL PROJECT LAYOUT
PREPARED FOR COMPARISON OF
ALTERNATIVE SITE DEVELOPMENTS ONLY
25+00 30+00 3!:i+OO
0 100 200 FEET
SCALE C
0 200 400 FEET
SCALE B
0 500 lOOOFEET
SCALE A
II M~~~ 1~---A~L A~S=K~A-ccP=O=W=-cER=AU""T=H::-::O=R 1:--T~Y --1
SUSITNA HYDROELECTRIC PROJECT
WATANA
HYDRO DEVELOPMENT
FILl,. DAM
h "''· ~~'·:::· ------------ACAES AM£1t1CAN INCORPORAT£D
PLATE
8.2
,---1 ,.,--~ ~ 1 ,-----~~ '1 l "'""'""' -~ -1 -l '1 -~'-----] l p--~--~-l -~-~--=-----1 1 -=-----, , ____ ] --------'} --·-~-") 'l
2300 ,--------
!'
~ 1900 ~--------------~~---~~~-4n~~L-~~~~~~~-,~~------------
~ 1800 ;:;
~ 1roo r---------~~--------~~f----~
/ 1600 r-----~~~------~~-~,r~~~--,L---~~~~---r----~~--~~~---
SCALE: A
[
CREST EL. 22.25
2300,-----------~T_ i__O~ DAM (~!AG_~ __ lf! __ _
--------------------------------· -·-------------------------
2200 rs=~=-=;:;"o"::.;;:~-------------
1600
\OOOI----------------
1400
LONGITUDINAL SECTION THRU ~ OF DAM
SCALE: B
EXISTING OROUND SURFACE
ONE:'. OF SPILLWAY\ ~ORMAL MAX ~ \ W.L. EL.2200
2300 l ___ ___--__ -=:.:-:.__ --.---~--------~---~EX~I~ST0-IN~G~GR~O~U~NOo-=Soc.UR00Fc-AC~E~ON~
2200 • -----_ -------~ RIGHT SIDE OF SPILLWAY
ZIOO r-;~. 20001 \ --~--_.: __ _!~!~_:-·--------~-&:.:?;; , ~"'---'"-_--"'-_-'-' _= _= _'-' _-_-_-_---~-:-~~~
ZOOO ____.!------·· &-WHEEL WOUNTEO GATE · ~-~~~----=-=----::-:-:~----_ '/(,{11!.,!-q
2300
2100
~ 1900
~ 1800
i!i I TOO
>' ;! 1600
~ \000
1400
1300
~ 1900 ~~ ----~~...... '-.. .... __ ~~
~ ~ \....' \ l-35' DIA. CONCRETE LINED~-TUNNEL.S ~"'"'-/!:::;~_('~~-
~ ISOO SPILLWAY CONTROL STRUCTURE\.. -~ \ ~---"1-.-A """'' r~ EXISTING GROUND SURFACE ON ~ 1700 t===========~~=========~;;;:========~~~~~~~~~~;;;-'-~"""'-~·~ ''-"'~·'-;-:<~ --~EFT SIDE OF SPILLWAY ~w 1600 -~A"""-~--·---
SECTION THRU DAM
SCALE: B
CONCAE
POWER FACILITIES PROFILE
SCALE: B
SCALE B
SCALE A
200 400 FEET
800 1000 FEET
----~]
iii ISOO STAGE I SPILLWAY STAGE II_/ '-""'.__ =-·:·-· ~-..____ ~ :~~:::• TAILWATER
CONC. PLUG """"' ..._ ~ ~-------...._
!400~-------------------------------------------------------------------------------------------~~~~--~~~~~~~~~~-~i 1
1---A __ L=AS=K=A~PO=W=Ec--=R=AU,_,T,-,--H,---O=R=-IT __ Y---1
SUSITNA HYDROELECTRIC PROJECT
l>llO 1--------------------------------------------
500 500 1000 1!500 2000
STATIONING IN FEET
SPIL.LWAY PROFIL.E
SCALE: B
-----------------------------------
2500 3000 !SOO 4000
NOTE
THIS DRAWING ILLUSTRATES A
PRELIMINARY CONCEPTUAL PROJECT LAYOUT
PREPA~D FOR COMPARISON OF
ALTERNATIVE SITE DEVELOPMENTS ONLY
WATANA
STAGED FILL DAM
PLATE
8.3
1 "} 1 ~--·-1
GENERAL ARRANGEMENT
SCALE: A
1 ----1 --l ...... 1
LOP~
1------. ----···------~....._,""" rr ~~---~~c~;:~=~
LONGITUDINAL SECTION THRU fi OF OAM
SCALE: B
,,
II
r•-·J ···--1 1
1600
1~00
1400 ~------
000
GROUT
___ j
900f-----
1 c•-1 "1 --]
NORMAL MAX. WL EL 11~'-] .
0
SCALE A
0
SCALE B
SECTION THRU DAM
SCALE: B
500 1000
STATIONING IN FEET
POWER FACILITIES PROFILE
SCALE: B
"'0 1000
STATIONING IN FEET
SPILLWAY PROFILES
SCALE: B
400 800 FEET
200 400 FEET
NOTE
'\.tHIS DRAWING ILLUSTRATES A
PRELIMINARY CONCEPTUAL PROJECT LAYOUT
PREPARED FOR COMPARISON OF
ALTERNATIVE SITE: DEVELOPMENTS ONLY
1000
1500
··--~ l 1 1
-----
_----= ~1
2000 2500
--------·-
2000
i~ 1--A-cL A:::::S""'K:;-;A-::P=O=W=E=R =A=U=T H=-O=R=-IT_Y--1
SUSITNA HYDROELECTRIC PROJECT
HIGH DEVIL CANYON
HYDRO DEVELOPMENT
-~~--
ACRES AloiERICAtol INCORPORATED
PLATE
8.4
--~<<<] -~---1
Z50~
~--~------2400--------~-
Z300~~-~
~--
<Cl
" / INTAKE
<~ -~~
2200------------~
--
,-~-~--] << 'J l --~ '') -~-1 l >~1 ,...,·~~ l
~f~~~:~OMAX W,L
-----~-----
~2000
~ 1900
~!BOO-----
-l )
SECTION THRU DAM
SCALE: B
/-1700L---------
,__/
-~/
~----~~
"<-~-~~~
//
~-<~------~-~-~~~--
!BOO'------------
GENERAL ARRANGEMENT
SCALE:= A
CREST EL. 2360
rAT il OF DAM
LONGITUDINAL SECTION THRU t OF DAM
SCALE: B
SLOPE
POWER FACILITIES PROFILE
SCALE: B
STATIONING IN FEET
SPILLWAY PROFILE
SCALE: B
SCALE A 0~~~40ii,i;Oii;;;;;;;;iiBiiOO
------SCALE B O~~~Z005;;;;;;;;;ii4~00
THIS DRAWING ILLUSTRATES A
PRELIMJfo.IARY CONCEPTUAL PRO.JE.CT LAYOUT
PREPARED FOR COMPARISON OF
ALTERNATIVE SITE DE'f'E.LOPMENTS ONLY
l 1
1i11--A_L_ A,--,S~K~A_P-ccO=W=-E=R =A=UT=Hc=-O=R=-IT_Y--1 lAJiiiNJ SUSITNA HYDROELECTRIC PROJECT
SUSITNA m
HYDRO DEVELOPMENT
PLATE
8.5
,--~ f'0'--'1
~-
DIVERSION~·--
INTAI<E ~
DIVERSION
TUNNELS
..
~
"'
2400
2300
2200
2100
2000
1900
I BOO
'"' •'
--o--, ·----] --~1
GENERAL ARRANGEMENT
SCALE A
CRESl EL 2350
LONGITUDINAL SECTION THRU l OF MAIN
SCALE B
l 1 -l
SADDLE DAhl
---2300
2400
2l00 ..
~ 2200
~
~ ,. 2100
z 2000 0 ;::
~ 1900
1800
Z600
2!500
2400
2.300
~ 2200
~ 2100
z
0 2000
DAM ~ 1900
1800
-500
,,·---1 .----o-o_ -l ·-~,--'1 ,-~-1 1 -,-~,--)
NORMAL MAX.
2400
~330
2300
~-..
~ 2200 ~
~
~ 2.100
z :zoo a 0
~ 1900
~ 1800
1700
FINE FILTER
1600
SECTION THRU DAM
SCALE B
-500 500 1000 1~00
STAliONING IN FEET
POWER FACILITIES PROFILE
SCALE 8
STATIONING IN FEET
SPILLWAY PROFILE
SCALE 1!1
500 1000 1500
THIS DRAWING ILLUSTRATES A
PRELIMINARY CONCEPTUAL PROJECT LAYOUT
PREPARED FOR COMPARISON OF
ALTERNATIVE SITE DEVELOPMENTS ONLY
DRAIN
~-~-,--l ~-1
SCALE B 0~~!!2!50ii;O;;;;;;;;;i4ii;j00 FEET
SCALE A O~~~·~~~Oii;OiiiiiOiiiBiilOO FEET
,., ____ ]
l
riil_m I--A-cL;;;-;AS;;;:;K:;:-:A:-cP::::O::::W:::cE-:::R::::A;;;:U-:::T::;cHOc::cR~IT_Y---1 lBii SUSITNA HYDROELECTRIC PROJECT
VEE
HYDRO DEVELOPMENT
PLATE
8.6
i \
(
\
ERSION
2450-~ ·~·
2400
2:300
~ w 2200 w ..
;!
z
2
~ 2400
1!300
2200
MACLAREN
GENERAL ARRANGEMENT
SCALE• A
DAM CROSS SECTION
SECTION B-B
SCALE• C
SCALE• C
SECTION A-A
SECTION C-C
-l
~-----j
______ j
~)
( ..
i -I ,-
l/
I
/
/
DENALI
GENERA~NGEMENT
SCALE•A
DAM CROSS SECTION
1 l
DOUBLE BELLMOUTH / TRASHRACI<S
INLET-------------r-j--, STILLING BASIN
TEMPORARY OPENiri~------------' . .
FOR DIVERSION •
2-32' K32' CONDUITS
AILWATER ~ -
-16 1132' FIXED
WHEEL GATES
SECTION D-D
SCALE• C o;.....,.,;;'Oi,i0iiiiioiiiiii2~00 FEET
SCALE•B
SCALE-A
~..,,;•,;;oo;.,iiiiii•ioioo FEET
400 BOO FEET
1'"N~O~T~Eiiiiiiiiiiiiiiiiil
THIS DRAWING ILLUSTRATES A
PRELIMINARY CONCEPTUAL PRO~CT LAYOUT
PREPARED FOR COMPARISON OF
ALTERNATIVE SITE DEVELOPMENTS ONLY
SCALE• C
I I~~~~~ 11--A---cL ;;;-;AS;o;;;K;;-;-A~PO:;;;:W:=E~R=A::::U:-:T~H:-::O:::R::-IT_Y-1
SUSITNA HYDROELECTRIC PROJECT
DENALI a MACLAREN
HYDRO DEVELOPMENTS
PLATE
8.7
1
---
sUSLTNA RIVER
~
------···-... /~ 1~0~ ··•
GENERAL ARRANGEMENT
RE·REGULATION DAM
"'0 ~~~~~~~~~·l!iOOii;;;iiii~OOO FEET
SCALE ~
... -·-1 1
GENERAL ARRANGEMENT
DEVIL CANYON POWERHOUSE
SCALE ~llllllllllli4~0~0iiiiiiii8~00 FEET
THIS DRAWING ILLUSTRATES A
PRELIMINARY CONCEPTUAL PRo.JECT LAYOUT
PREPARED FOR COMPARISON OF
ALTERNATIVE SITE DEVELOPMENTS ONLY
)
I ~~ r---A-..,LA=S=K=A-::P=O=W=E=R=A=U=TH:-::-O=R=IT_Y---1
SUSITNA HYDROELECTRIC PROJECT
PREFERRED TUNNEL
SCHEME 3
PLAN VIEW
ACRES AMERICAN INCORPORATED
PLATE
8.8
"l
1600
1000
14001-----
~ z 1>00
~ 1200~~~-
IIOOL-
RE-REGULATION DAM TYPICAL SECTION
SCALE A
POWER TUNNEL INTAKE SECTION
SCALE A
40'W 1 43'H FIXED
WHEEL GATES
1600
1500
1<00
1>00
r~:t--
!< ~ w 1000
900
300T --~--I I
.ooo-1-+ I
2~ --+-
-~,
500
NORMAL T.W.L. -i
1
GATE/SURGE
CHAMBER
10
DISTANCE IN WILES
TUNNEL ALIGNMENT
~~7---EL.I2.60' ,I
DEVIL CANYON POWER FACILITIES PROFILE
SCALE A
DETAIL A
ROCK BOLTS AS
REQUIRED
l
A
BEARING PAD
CONC. UNED W/ STEEL SET
TYPICAL TUNNEL. SECTIONS
(N:T.S)
SPILLWAY PROFILE
SCALE A
SECTION A
ROCK BOLT~.
TYPICAL TUNNEL SECTIONS
IN.T.S.l
-------
ORILutOLE
FAST SETTING
J;ROUT
HEX NUT
I'DIA, ROO< E<l~ STEEL PLATE
GROUT AS REQUIRED (TYP)
THIS DRAWING ILLUSTRATES A
PRELIMINARY CONCEPTUAL PROJECT LAYOUT
PREPARED FOR COMPARISON OF
ALTERNATIVE SITE DEVELOPMENTS ONLY
0
SCALE A
100. ~00 FEET
~iii~ 1--AL~A--ccSc=-K_A_PO~W~E_R~A~U_-~TH,.,...O_R_IT_Y---t
1 UII!Jiru SUSITNA HYDROELECTRIC PROJECT
PREFERRED TUNNEL
SCHEME 3
SECTIONS
PLATE
8.9