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Chakachamna Hydroelectric Alternative
for the RaiJbelt Region of Alaska
Volume XIV
Ebasco Services Incorporated
Bellevue,Washington 98004
August 1982
Prepared for the Office of the Governor
State of Alaska
Division of Policy Development and Planning
and the Governor's Policy Review Committee
under Contract 2311204417
Battelle
Pacific Northwest Laboratories
Rich1and,Washington 99352
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ACKNOWL EDGME NTS
The major portion of this report was prepared by the Bellevue,Washington,
and Newport Beach,California,offices of Ebasco Services Incorporated.Their:
work includes the Introduction,Technical Description,Environmental and Engi-
neering Siting Constraints,Environmental and Socioeconomic Considerations and
Institutional Considerations.Capital cost estimates were prepared by
S.J.Groves and Sons of Redmond,Washington,and reviewed by the Ebasco cost
estimating department in New York City.Cost of energy estimates were pre-
pared by Battelle,Pacific Northwest Laboratories of Richland,Washington.
iii
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PREFACE
./
The state of Alaska,Office of the Governor,commissioned Battelle,
Pacific Northwest laboratories (Battelle-Northwest)to perform a Railbelt
Electric Power Alternatives Study.The primary objective of this study was to
develop and analyze long-range plans for electrical energy development for the
Railbelt Region (see Volume I).These plans will be used as the basis for
recommendations to the Governor and Legislature for Railbelt electric power
development,including whether Alaska should concentrate its efforts on
development of the hydroelectric potential of the Susitna River or pursue
other electric power alternatives.
Substantial hydro resources exist in the Railbelt Region.Many of these
resources could be developed with conventional (-lS MW installed capacity or
larger)hydroelectric plants.Several sites have the potential to provide
power at first-year costs competitive with thermal alternatives and have the
added benefit of long-term resistance to effects of inflation.However,high
capital investment costs render many sites noncompetitive with alternative
sources of power.
Environmentally,hydroelectric options are advantageous because they
produce no atmospheric pollution or solid waste.However,environmental
disadvantages may include the destruction and transformation of habitat in the
area of the reservoir,destruction of wilderness value and recreational
opportunities,and negative impacts on downstream and anadromous fisheries.
Based on environmental and economic considerations,the Chakachamna
hydroelectric project was among several hydroelectric projects selected as
possible alternatives to the Upper Susitna project.An individual study of
the Chakachamna project was commissioned for several reasons.First,the
prospective capacity and energy production of the Chakachamna project would be
greater than for any of the other selected alternatives to the Upper Susitna
project,yet not so large as to result in underutilization of the facility.
Second,preliminary estimates of the cost of energy from the Chakachamna
project appeared to be very favorable,partly because it would be a lake-tap
project and no dam would be required.Finally,because it would be a
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lake-tap project,it appeared that the potential environmental effects of the
project would be moderate compared to other alternatives.This report,
Volume XIV of a series of seventeen reports,documents the findings of this
study.
Other power-generating alternatives selected for in-depth study included
pulverized coal steam-electric power plants,natural gas-fired combined-cycle
power plants,the Browne hydroelectric project,large wind energy conversion
systems and coal-gasification combined-cycle power plants.These alternatives
are examined in the following reports:
Ebasco Services,Inc.1982.Coal-Fired Steam-Electric Power Plant
Alternatives for the Railbelt Region of Alaska.Prepared by Ebasco
Services Incorporated and Battelle,Pacific Northwest Laboratories
for the Office of the Governor,State of Alaska,Juneau,Alaska.
Ebasco Services,Inc.1982.Natural Gas-Fired Combined-Cycle Power
Plant Alternative for the Railbelt Region of Alaska.Prepared by
Ebasco Services Incorporated and Battelle,Pacific Northwest
Laboratories for the Office of the Governor,State of Alaska,
Juneau,A1ask a.
Ebasco Services,Inc.1982.Browne Hydroelectric Alternative for
the Railbelt Region of Alaska.Prepared by Ebasco Services
Incorporated and Battelle,Pacific Northwest Laboratories for the
Office of the Governor,State of Alaska,Juneau,Alaska.
Ebasco Services,Inc.1982.Wind Energy Alternative for the
Railbelt Region of Alaska.Prepared by Ebasco Services Incorporated
and Battelle,Pacific Northwest Laboratories for the Office of the
Governor,State of Alaska,Juneau,Alaska.
Ebasco Services,Inc.1982.Coal-Gasification Combined-Cycle Power
Plant Alternative for the Railbelt Region of Alaska.Prepared by
Ebasco Services Incorporated and Battelle,Pacific Northwest
Laboratories for the Office of the Governor,State of Alaska,
Juneau,Alaska.
During the course of this study,the Alaska Power Administration com-
menced a full-scale feasibility study of the Chakachamna hydroelectric proj-
ect,at a considerably greater level of effort than the present study.In the
feasibility study,initial analyses of project configuration resulted in the
selection of a configuration differing from that selected for the present
study.Th~configuration selected for the Bechtel feasibility study would be
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of 330 MW installed capacity,with an annual average energy production of
1570 GWh as compared to the 480-MW installed capacity project dis~ussed in
this report.Flow would be maintained in the Chakachatna River 10 support the
native anaaromous fishery,resulting in a reduction in energy production and a
need for less intalled capacity.Further information on the Bechtel feasi-
bility study is provided in Section 7.0 of this study.
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SUMMARY
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Numerous sites showing potential for hydroelectric development have been
identified in the Railbelt Region of Alaska.Many,however,appear at this
time to be uneconomic due to high capital costs,or appear to have the poten-
tial for unacceptably severe environmental impacts.Among the sites of suf-
ficient size to be of interest in the context of a Railbelt-wide electric
power planning and that present potentially competitive economic character-
istics and acceptable environmental impacts is the proposed lake-tap project
at Chakachamna Lake,located about 85 miles west of Anchorage.
The proposed Chakachamna hydroelectric project would be a lake-tap hydro-
electric development consisting of an intake structure at Chakachamna Lake,a
transmountain pressure tunnel,approximately 10.8 miles in length,a surge
tank,a vertical shaft to the powerhouse elevation,penstocks and a powerhouse
discharging to the McArthur River.The installed capacity of the design
examined in this report would be 480 MW.
Power from the project would be transmitted at 230 kV,approximately 55
miles to the existing transmission corridor of the Chugach Electric Associa-
tion Beluga Station,and thence to Anchorage along the common corridor.The
estimated annual average energy production would be 1892 GWh and the estimated
annual firm energy production would be 1859 GWh.
Cost estimates for the proposed project indicate an overnight capital
cost of approximately ~2100/kW,with operation and maintenance costs of
3.75 $/kW/yr.Assuming a 1991 in~service date,levelized busbar energy costs
are estimated to be 25.5 mills/kWh (January 1982 dollars).
Approximately 9-1/2 years would be required for project completion,
including preconstruction studies,licensing,design,construction and
startup.A 50-month construction period would be required.Under this
schedule,the earliest in-service date,assuming a mid-1982 authorization to
proceed,would be late-1991.
Environmental effects of the Chakachamna project could range from modest
to locally severe,depending upon project design and operation,the magnitude
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of the anadromous fisheries of the Chakachatna and McArthur Rivers and the
impact of project operation on downstream fisheries.Principal potential
environmental impacts include destruction of the existing sockeye run into
Chakachamna Lake from the Chakachatna River;disturbance of the downstream
Chinook and pink salmon fisheries of the Chakachatna and McArthur Rivers;
disturbance of resident fisheries of Chakachatna and McArthur Rivers;
terrestrial habitat changes due to dewatering of the Chakachatna River.
drawdown of Chakachamna Lake and flow increases in the lower McArthur River;
effects of vehicular access to the Chakachatna and McArthur River valleys and
to Chakachamna Lake;and effects of the construction work force on local
communities.Destruction of the Chakachatna sockeye run could be alleviated'
by alternative project design and operational procedures allowing maintenance
of Chakachatna flow during migration periods and control of lake level to
facilitate spawning.
Physical features of the site that may pose potentially severe engi-
neering constraints include the general seismicity of the project area,
potential faulting in the vicinity of the pressure tunnel,proximity of the
Mt.Spurr Volcano and effects of Chakachatna River dewatering upon Barrier
Glacier,which controls the outlet to Chakachamna Lake.Provisions for these
engineering conditions,as they are currently understood,have been incor-
porated into the proposed project design.Field investigation of site
characteristics.particularly the geologic conditions along the route of the
pressure tunnel.will be required,however,prior to arriving at a final
project design.
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CONTENTS
ACKNOWLE DGMENTS
PREFACE
SUMMARY
1.0 INTRODUCTION
2.0 SITE DESCRIPTION
2.1 SITE •
2.1.1 Geology,Seismology,and Volcanism
2.1.2 Hydrology
2.2 PLANT
2.2.1 Overview
2.2.2 Reservoir
2.2.3 Tunnel,Surge Tank,and Penstock.
2.2.4 Power Plant •
2.3 TRANSMISSION SYSTEM.
2.4 SITE SERVICES •
2.5 CONSTRUCTION
2.5.1 General Constructon Methods.
2.5.2 Construction Schedule •
2.5.3 Construction Work Force
2.6 OPERATION AND MAINTENANCE
2.6.1 General Operating Procedures
2.6.2 Operating Parameters
2.6.3 Project Life.
2.6.4 Operating Work Force and General
Maintenance Requirements
xi
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ix
..1.1
2.1
2.1
2.1
2.3
2.5
2.5
2.15
2.17
2.18
2.23
2.24
2.25
2.25
2.26
2.31
2.31
2.31
2.32
2.35
2.35
....
3.0 COST ESTIMATES .3.1
3.1 CAPITAL COSTS .3.1
3.1.1 Construction Costs 3.1
3.1.2 Payout Schedule 3.1
3.1.3 Escalation 3.1
3.2 OPERATION AND MAINTENANCE COSTS 3.4
3.2.1 Operation and Maintenance Costs .3.4
3.2.2 Escalation 3.4
3.3 COST OF ENERGY .3.4
4.0 ENVIRONMENTAL AND ENGINEERING SITING CONSTRAINTS .4.1
4.1 ENVIRONMENTAL SITING CONSTRAINTS 4.1
4.1.1 Water Resources 4.1
4.1.2 Air Resources 4.2
4.1.3 Aquatic and Marine Ecology .4.2
4.1.4 Terrestri~l Ecology 4.2
4.1.5 Socioeconomic Constraints 4.2
4.2 ENGINEERING SITING CONSTRAINTS 4.3
5.0 ENVIRONMENTAL AND SOCIOECONOMIC CONSIDERATIONS 5.1
5.1 SUMMARY OF FIRST ORDER ENVIRONMENTAL IMPACTS .5.1
5.2 ENVIRONMENTAL AND SOCIOECONOMIC EFFECTS .5.1
5.2.1 Water Resource Effects .5.1
5.2.2 Air Resource Effects 5.3
5.2.3 Aquatic and Marine Ecosystem Effects .5.3
5.2.4 Terrestrial Ecosystem Effects 5.4
5.2.5 Socioeconomic Effects .5.5
xii
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6.0 INSTITUTIONAL CONSIDERATIONS ·· ···6.1
6 .1 FEDERAL REQUIREMENTS ······../:·6.1
6.2 STATE REQUIREMENTS ····6.2
6.3 LOCAL REQUIREMENTS ·········6.5
7.0 ONGOING PROJECT STUDIES ·········7.1
8.0 REFERENCES · ···8.1
xiii
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FIGURES
1.1 General Site Plan and Geologic Features •
2.1 Detailed Site Plan
2.2 Project Profile
2.3 Transmission Corridor and Plant Access Roads.
2.4 Powerhouse Plan
2.5 Powerhouse Section
2.6 Project Schedule
2.7 Construction Work Force Requirements
3.1 Cost of Energy Versus Capacity Factor
3.2 Cost of Energy Versus First Year of Commercial
Operation .
xiv
1.2
2.7
2.9
2.13
2.19
2.21
2.27
2.32
3.5
3.6
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TABLES
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19
21
27
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2.1 Average Monthly Discharge at Outlet of Lake
Chakachamna
2.2 Chakachamna Hydroelectric Project Summary
of Project Features .
2.3 Project Operation During Average Hydrologic Year
3.1 Bid Line Item Costs for the Chakachamna Hydroelectric
Project
3.2 Payout Schedule for the Chakachamna Hydroelectric
System
3.3 Year-of-Occurrence Energy Costs
5.1 Primary Environmental Effects.
6.1 Federal Regulatory Requirements
6.2 State Regulatory Requirements.
7.1 Project Development Alternatives
xv
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1.0 INTRODUCTION
The proposed Chakachamna project is a transmountai n di vers i6n and hydro-
electric power development project (refer to Figure 1.1).Chakachamna Lake,
located about 85 air miles west of the City of Anchorage,would be utilized as
a storage reservoir.Water would be conveyed through a pressure tunnel and
penstock to a power plant located on the McArthur River at latitude 61~05IN,
longitude 152°11 I W.The power output would be transmitted to Anchorage,the
principal outlet for the sale of electrical energy to the Railbelt Region.
The instal lea capacity of the project would be 480 MW.
The advantages of the project may be categorized both generically,as
related to hydro power,~nd on a site-specific level.In a generic sense,the
pertinent advantages 'of hydro power include zero fuel costs,maturity of tech-
nology,simplicity,reliability,and quick responsiveness of the generating
equipment.The Chakachamna site is considered to be advantageous from cost,
project size and environmental standpoints.A study of alternate non-Susitna
hydro generating sources in Alaska identified a total of 91 potential sites.
Of the 91 sites,10 were selected for more detailed development and cost esti-
mates (Acres American,Inc.1981).From this study,Chakachamna was ranked as
having the lowest economic cost of energy,and therefore represents a poten-
tially attractive alternative to the Susitna project from an economic stand-
point.The prospective size (480 MW installed capacity,1923 GWh average
annual energy)is desirable in the context of the existing size of the
Railbelt electric power system.The project would be of sufficient size to
allow displacement of more expensive thermal generation (especially if the
Anchorage-Fairbanks electrical intertie is completed as proposed)yet is not
so large as to result in underutilization.
Environmentally,the principal impact would be disruption of the flow of
the Chakachatna River with resulting impact on the anadromous fishery of this
stream.The facility could be operated,however,to maintain streamflow
during critical migration periods.As the project is of the lake-tap variety,
impacts of reservoir construction would be absent.
1.1
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FIG~RE 1.1.General Site Plan and Geologic Features
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The project site.however.possesses certain disadvantages.Geolog-
ically.the Lake Clark-Castle Mountain fault zone.a seismically)active fault.
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lies about 11 miles east of Chakachamna Lake (see Figure 1.1)and very close
to the site of the proposed powerhouse.This fault may affect the stability
of the Chakachamna storage reservoir.especially with regard to the Barrier
Glacier ice-moraine dam that forms the downstream boundary of the reservoir.
Approximately 5 miles to the northeast of Chakachamna Lake is the 1l.070-foot-
high Mount Spurr,an active volcano.Ash falls and mud slides resulting from
an eruption of Mount Spurr may seriously impair the operation of the
Chakachamna reservoir as well as the integrity of the Barrier Glacier
ice-moraine dam.Also,there is uncertainty about the composition of this
ice-moraine dam and the possible effect that the proposed reservoir operation
might have on future movement of the glacier tongue.especially if it proved
to be active at its downstream extremity that presently forms the left bank of
the Chakachatna River as it leaves Chakachamna Lake.
Logistically.the location of the project presents some further dis-
advantages.Due to the remoteness of the project.a considerable amount of
road construction and communication and transmission facilities would have to
be provided.
These disadvantages,.both geologic and logistic,are discussed in more
detail in the following sections.
As an alternative to the selected transmountain diversion scheme.consid-
eration was given to constructing a dam across the Chakachatna River 6 miles
below the outlet of Chakachamna Lake,and developing the head along the river
itself for power.This alternative was.however.subsequently abandoned
becaus~of difficulties associated with constructing the dam.which were
recognized during an Ebasco site reconnaissance visit.The foundation.and
especially the left abutment geologic conditions.are unfavorable for con-
structing a dam anywhere along the upper Chakachatna River.Also,the high
seismic design factor due to the close proximity of the Lake Clark-Castle
Mountain fault zone may seriously impair the stability of a dam built in this
area.
..
1.3
2.0 SITE DESCRIPTION
.1
2.1 SITE
2.1.1 Geology,Seismology,and Volcanism
The water storage reservoir for the project,Chakachamna Lake,is a
glacier-formed lake surrounded by mountains that are part of the Alas~a Range
near the Cook Inlet Lowlands.The mountains surrounding the lake rise to
above 5,000 feet elevation and support many active glaciers,one of which dams
the Chakachatna River at the outlet of the lake.The region is both seis-
mically and volcanically active,with major northerly-dipping thrust of
strike-slip faults paralleling Cook Inlet,and a line of active volcanoes
landward of the faults.The dominant geologic features of the site area are
as follows:
•About 60 miles to the east of Chakachamna Lake,the Lake Clark-Castle
Mountain fault zone,a 350=mile-long fault,is known to have offset
Holocene sediments,and Recent sediments dated to between 260 and
1800 years ago.This fault passes within approximately 11 miles of
Chakachamna Lake and a preliminary estimate of the potential magni-
tude of a seismic event along this feature is 7+.The potential for
seismic activity generally increases as one proceeds southward along
the fault.
•An active volcano,Mount Spurr,is located about 5 miles to the
northeast of Barrier Glacier.This volcano erupted ash in 1953 and
caused a mudslide that temporarily dammed the Chakachatna River
6 miles downstream of the lake outlet.Similar mudflows could
conceivably alter the nature of the ice-moraine dam that forms
Chakachamna Lake,render inservicable the intake structure to the
power tunnel,and otherwise affect the feasibility or useful life of
the project.
•Lake Chakachamna is formed by a natural dam at its eastern end,con-
sisting of glacial morainal deposits from the still active Barrier
Glacier.This glacier is an active alpine-type ice stream that
2.1
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descends the southwest slope of Mount Spurr and spreads into an
expanded fan-shaped tongue for a distance of 2 miles across the
Chakachatna River valley.This results in a confinement of nearly a
1 mile reach of the Chakachatna River into a narrow channel at the
base of the steep mountainside on the south side of the valley.
However,during the last 30 years,evidence points toward a trend of
slow recession and shrinkage of the glacier •.The exception to this
trend is the advancement of one ice lobe on the glacier that is
believed to be the result of Mount Spurr's 1953 eruption.With the
development of the Chakachamna powersite and the resulting long
periods of lake drawdown,the erosive ~ffects of the existing
Chakachatna River on the Barrier Glacier will be diminished.It is
believed that this may result in the advancement of Barrier Glacier
and closure of the short gap to the ~orth of the mountainside wher~
the river currently flows.
Surperficial deposits in this area include gravels,sands,and silts that
form river deltas and beach deposits at the entrances of the Nagishlamina,
Chilligan,and Neacola Rivers.A large glacial moraine is present at the base
of More Glacier.The streams that feed LakeChakachamna are all laden with
sediment.The sediment is primarily II rock-flour ll of gl aci al ori gi n,and much
of it seems to stay in suspension even after it reaches the calm waters of the
lake.There are no firm data available as to the rate of accumulation of sedi-
ment in the lake,but the abrupt IIl eve ling off"of the lake bottom at depths
below 240 feet is an indication of a considerable-accumulation of sediment.
Aerial photographs of this region show a series of parallel lineaments
that trend roughly NW-SE.These features are quite evident in the field,and
Seem to extend for some distance.They are nearly vertical,and close exami-
nation shows severe fracturing and pulverization in the fault or fracture
zone.A tunnel from Lake Chakachamna to the McArthur River Valley would
roughly parallel the strike of these features.
2.2
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Tunnels and related structures would be excavated in granitic rocks as
indicated on existing geologic maps of the region.These maps show that the
alignment would cross a zone of contact between granitics of tw;'different
periods of intrusion.Older greenstones outcrop directly to the north of
Chakachatna River and these same rocks could conceivably outcrop along the
tunnel route.Site inspections have shown generally favorable geologic
conditions for tunnel portals where steep faces of relatively fresh to~k are
exposed.The powerhouse would be located 11 miles south of the lake on the
McArthur River,between the floodplain and an active talus slope.
2.1.2 Hydrology
The entire drainage area contains lofty,rugged mountains with numerous
large glaciers in the valleys and perpetual ice fields in the higher eleva-
tions.These glaciers and ice fields comprise 20 percent of the 1,120 square
miles of drainage area.Mountain peaks are in the range of 6,000 to
10,000 feet in elevation,with the highest peak being Mount Torbert at ele-
vation 10,600.Mount Spurr,an active volcano just outside the drainage area,
rises to elevation 11,070 feet.Merrill Pass lies 18 miles to the west of
Chakachamna Lake at an elevation of about 3,100 feet.
The generally southeastern exposure of the drainage area receives mois-
ture from the storms moving inland through Cook Inlet.The principal streams
contributing to Chakachamna Lake are the Neacola and Chilligan Rivers,each
about 24 miles in length.Other streams include the Nagishlamina and the
Igitna.Three of these streams terminate in Kenibuna Lake located directly to
the west of Chakachamna Lake.Kenibuna Lake,in turn,empties into Chakachamna
Lake.All streams except for the Chilligan River originate in glaciers.
The U.S.Geological Survey established a recording stream gaging station
on the Chakachatna River at the outlet of the lake on June 14,1959.This
station,identified by the U.S.Geological Survey as "Chakachatna River near
Tyonek,Alaska,"was in continuous operation until 1972.A tabulation of the
monthly historical discharges at this gage is shown in Table 2.1.The average
monthly discharge for the 13-year period of record (extending from water year
1960 through water year 1972)is 3651 cfs.The monthly discharges recorded at
2.3
...
·''.J TABLE 2.1.Average Monthly Di scharge at Out let of Lake Chakachamna (cfs)(a)
Water
Year Oct Nov Dec Jan Feb Mar Apr May Jun Jul ~Sep--
1960 2022 992 658 504 381 325 250 1483 6368 10500 10300 4364
1961 1800 1116 882 817 780 544 394 876 5673 12090 12330 6989
1962 2638 1200 730 690 630 540 470 620 5222 13000 11060 6904,1963 1827 1144 744 553 387 361 332 748 3441 12640 12240 7737
1964 2768 1384 1007 618 436 424 370 471 6287 10590 12030 5654
N 1965 2026 1090 852 620 449 360 350 525 2117 10020 13810 10260.
+>-1966 4072 1180 650 480 400 350 350 615 5995 10040 10310 7145
1967 3790 1100 820 600 500 430 380 935 6616 14380 16610 7333
1968 2939 1565 947 626 535 490 511 1695 6190 12580 12170 4369
1969 1552 939 723 639 550 500 533 1033 6548 13100 8416 3347
1970 3098 1822 1066 705 568 550 625 1285 4893 9960 8884 3587
1971 2201 1247 829 532 467 467 692 2381 10930 14470 16710 4513
1972 1351 902 726 585 484 446 481 906 4294 12860 12750 6995
(a)From USGS Gage No.15294500 -Chakachatna River near Tyonek.
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this gage have been used as monthly reservoir inflows in the power operation
studies for the project and serve as a basis for the estimates of;"power output
'"and reservoir fluctuation.As discussed in Section 2.6.2,using the recorded
lake discharges to also approximate reservoir inflow values introduces some
error into the results of the reservoir operation studies for very wet or dry
hydrologic periods.More detailed feasibility analyses should therefore
utilize derived reservoir inflows for the power operation studies,computed by
adjusting the recorded discharge by the effect of storage in the lake.
2.2 PLANT
2.2.1 Overview
Lake Chakachamna would be utilized as the storage reservoir for the
project.Water would be conveyed from this reservoir via a 26-foot-diameter,
10.8-mile-long rock tunnel and a 26-foot-diameter vertical shaft,to the steel
penstocks,and ultimately to the powerhouse.The powerhouse would be located
on the McArthur River,approximately 25 miles upstream of the mouth of the
river at Cook Inlet.The average net operating head for the project is
estimated to be 867 feet.The major civil works are shown in plan and section
in Figures 2.1 and 2.2,respectively.A summary of the principal project
features is shown in Table 2.2.
The total installed plant capacity of 480 MW would be developed by four
120-MW reaction turbine-generators.The annual firm power output of the
project }s estimated to be 1,869,000,000 kilowatt hours.
The transmission of power would be over a 23Q-kV double-circuit line,
approximately 115 miles in length and terminating at a substation near
Anchorage.One transmission corridor alternate as well as the preferred route
are shown in Figure 2.3.
Due to the remoteness of the project,approximately 40 miles of access
roads will be required.The access road layout is also shown in Figure 2.3.
2.5
..
--
13
---.-----1---~_4I ..
l ;~1 11~
...'f'.,.~-.<..~~-.W \.-.,I1+--\-.....::-~~--'--~·-V --
\\(i N(f=
20·----
CONTOUR INTERVAL 100 FEET
NATIONAL GEODETIC VERTICAL DATUM OF 1929
FIGURE 2.1.Detailed Site Plan
2.7
18.5 <p STE EL PE NSTOCK
WITH DOUBLE BIFURCATIONS
INTO FOUR-8.5-FOOT~
DIAMETER STEEL PENSTOCKS
,/POWERHOUSE EL.I 85:!:
~_.MCARTHUR RIVER26'DIAMETER VERTICAL
POWER SHAFT
SLOPE261DIAMETERPOWERTUNNEL
T~_._.T ~L-i_I..__~--.IT_'_~'---_~
GLACIERS
INVERT EL.916
POWER TUNNEL INTAKE--------------------------------------------------------------------------
oo
'\t
~Id ~
5000 -----~I W -------------------------------------7--=;;;;-~---
-I U W~4000 --I j ~I ~------------------------------------------------~
"""ex>t-3'W en~wO oc~m~X~WI~~OO--d d~~-----------------~-------------------~~-------~--------------~~---
~.~~en 4 I
~34W 00~2000-~l g ~I g --~--------------------------------.--------------~..----~I ~---
~1000 ~k::~GATE SH~:------------.-~.INVERT EL.862
~
W LAKE
CHAKACHAMNA
o
SCALE
HORZ.1"=I MILE
VERT.1"=2000'
FIGURE 2.2.Project Profile
2.9
"
TABLE 2.2.Chakachamna Hydroelectric Project Summary
of Project Features
"
Adit Tunnels
Power Tunnel
Power Shaft
Gate Shaft
Spi 11 way Tunnel
11,300 lineal feet
30 ft diameter
5 percent steel sets (W 12 x 65)
10 percent shotcreted and rockbolted (10-ft bolts)
57,000 lineal feet
26 ft diameter -circular cross section
10 percent concrete lined (1.5 ft)with steel sets
(W 8 x 31 to W10 x 49)
20 percent shotcrete lined (4 in.)and rockbolted (10-ft
bolts)
70 percent unlined
685 lineal feet,26 ft diameter
5 percent steel set supported (W 8 x 31)
20 percent rockbolted (10-ft bolts)10 percent shotcreted
(4 in.)
500 lineal feet
20 ft diameter
concrete lined (1.5 ft)for entire length
13,200 lineal feet
30 ft diameter
10 percent steel sets (W 12 x 65)
20 percent snotcreted (4 in.)over rockbolts (10-ft bolts)
80 percent unlined
Surge Tank
Steel Penstocks
70 ft diameter,400 ft high
50 percent rockbolted (15 ft bolts)
30 percent 2 ft concrete lined,60 percent unlined
1-18.5 ft diameter,700 lineal feet
4-8.5 ft diameter,100 lineal feet
Powerhouse 480 MW installed capacity
Francis Turbines 4 -166,000 hp,867 ft net design head
Generators 4 -133,300 kVa,300 rpm at 0.9 pf
Outside Powerhouse dimensions:width:120 ft
length:320 ft
hei ght:120 ft
Switchyard dimensions:300 ft x 100 ft
Tailrace Channel:width =200 ft
depth =20 ft
length =1000 ft
Access Roads:40 miles;2 single span bridges near Lake Chakachamna
Transmission Lines:115 miles,230 kV
55 miles of new corridor
60 miles adjacent to existing corridor
2.11
1520 R 15 W
.'
R.14 IN R.13 W.30'R.12 W.R.II ....
.'.i
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R 10W 151"
....
.
FIGURE 2.3.Transmission Corridor and Plant Access Roads
2.13
"-,
2.2.2 Reservoir
The reservoir is anticipated to have a normal maximum wate~iurface
elevation of 1127 feet.At this elevation,the length of the lake is about
15 miles and the surface area is 15,250 acres.It is estimated that a total
of 4,150,000 acre-feet of volume exists in the lake below elevation 1127.The
lowest elevation obtained from soundings is 762 feet.Operation studies
indicate that approximately 2,080,000 acre-feet of storage in the lake would
be utilized for regulation of power releases.
The reservoir would be operated to store as much runoff as possible
during the summer months when runoff is high.Regulated flows would be
released for power generation throughout the year.Normally,runoff would
fill the lake from mid-May to October.Any flood flows would spill from the
lake into the Chakachatna River through a natural spillway at elevation
1127 feet.This natural outlet is located at the east end of Lake
Chakachamna.Beginning in October the lake would be drawn down gradually
during the winter months,reaching minimum elevation in mid-May,when the
cycle would start again.The results of reservoir operation studies performed
for the project indicate that during an average hydrological year the lake
would be drawn down to a minimum level of elevation 1019 in May with the
average reservoir level for the entire year being elevation 1076.The minimum
reservoir level determined in the operation studies was elevation 968,which
occurred only once during the period of hydrologic record.
An emergency spillway outlet has been included in the conceptual layout
of the project in addition to the natural spillway that presently exists at
the east end of Chakachamna Lake.The justification for including the
emergency spillway outlet is based on the difficulty of predicting,with
certainty,the future movements of the Barrier Glacier,especially when
essentially all of the runoff into the lake becomes diverted for the
production of power.Significant future glacier movement could cause it to
completely seal off the only natural lake outlet.The uncertainties
associated with the movements of this glacier and the need for additional
studies are discussed in more detail in Section 4.2 of this report.
2.15
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1-,
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11.,
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H,
It fl
This concern is further emphasized by the USGS-1972 Water Resources Data
for Alaska report,which describes the occurrence of a maximum lake discharge
of 470,000 cfs.This flow was not measured at the outlet gauge,but was
estimated through the observations of high water marks of the flood downstream
of the lake.A flood of this magnitude would indicate that at some time in
the past the glacier did,in fact,move sufficiently to close off the natural
lake outlet.This would have subsequently resulted in a lake buildup that
ultimately overtopped and then quickly eroded the glacier.
For estimating purposes,a 3D-foot-diameter,2.5-mile-long emergency
spillway tunnel located in the right abutment of the lake outlet has been
indicated (see Figure 2.1).The actual required diameter may vary somewhat
from 30 feet but this would have to be determined through detailed hydrologic
studies.This tunnel would have an invert elevation of approximately 1130 at
the upstream end and would sl.ope gradually to its outlet on the Chakachatna
River.The upstream portal of this tunnel would be located in the steep
granite face on the right bank of the outlet,roughly 500 feet south of the
natural river channel at the outlet.For estimating purposes,it is assumed
that the tunnel would be unlined for approximately 80 percent of its length.
A reconnaissance level estimate of the 100-year sediment inflow to the
lake has been determined as 1,350,000 acre-feet (USSR 1962).Of this total,
only about 70,000 acre-feet would be deposited in the active conservation
space.This is roughly three percent of the active storage capacity and is
therefore considered insignificant.Also,the annual loss due to evaporation
is estimated to be not more than one-half foot for a full reservoir.At
elevation 1127 feet this would amount to an insigificant 7250 acre-feet per
year,or 0.3 percent of the active storage capacity.
The intake structure to the power tunnel would lie within the south bank
of Lake Chakachamna,approximately 1 mile west of the lake outlet.This
location woulo place the portal within a steep granite slope.During
construction,the connection at the intake to th;tunnel would be formed by
blasting(~plug of rock.Subsequently,loose rock might be removed from the
intake by divers,but a concrete structure would not be built upstream of the
gate shaft.The invert (lower lip of intake)would be at an approximate
2.16
m
'"
elevation of 916 feet.It would be provided with a coarse trashrack~which
would be installed by divers.The purpose of this trashrack woul~be to
prevent large logs from entering the tunnel.
A gate shaft would be located in the power tunnel approximately 500 feet
downstream of the intake portal.This gate shaft would rise from the tunnel
line to above the water surface of Lake Chakachamna where an entrance
structure would be constructed at an elevation of 1400 feet.The shaft would
contain two fixed-wheel gates,30 feet high by 13 feet wide.These gates
would normally function as remotely controlled service gates and would be used
to close the tunnel only for dewatering and inspection.The gates could also
be closed by remote control during an emergency.
The shaft would also contain auxiliary gates immediately upstream of the
intake gates that would be closed during maintenance work on the main intake
gate.Finally,the shaft would contain a fine trashrack designed to withhold
all debris that may pass the coarse trashrack at the intake.
2.2.3 Tunnel,Surge Tank,and Penstock
Plan and section views of the water conductors are shown in Figures 2.1
and 2.2,respectively.Not shown in these figures,but immediately upstream
of the surge tank,would be a 10D-foot-long rock trap,formed by deepening the
tunnel to create a long shallow basin 3 feet deep.Rock pieces that enter the
tunnel would settle into this trap and not be carried into the turbines.
As discussed previously,the major portion of the power tunnel would be
26 feet in diameter and 10.8 miles long.The average flow in this main tunnel
would be 3650 cfs.
From a site reconnaissance level interpretation of geologic conditions,
as well as a review of available literature~it is felt that the rock is
sufficiently competent to allow the main tunnel to be unlined along most of
its route.It is estimated that approximately 10 percent of the tunnel would
require a reinforced concrete lining with steel sets.This lining would
probably be required at the inlet portal~for short distances along the tunnel
and at the tunnel-surge tank intersection.A minimal amount of shotcrete and
rockbolting (approximately an additional 20 percent)has also been assumed,to
2.17
__1 _
fa ~.
allow for jointing and changes in rock types.Lining and reinforcing at the
entrance portal would be accomplished subaqueously.
A 70-foot-diameter,40Q-foot-high surge tank would be located at the
downstream end of the main tunnel.The assumed lining and support require-
ments for the surge tank are shown in Table 2.2.
Emerging downwards from the surge tank would be a 26-foot-diameter ver-
tical shaft.For estimating purposes,it is assumed that this shaft would be
unlined for approximately 90 percent of its length with supports and minimal
shotcrete lining as defined in Table 2.2.Lower down,an l8.5-foot-diameter
steel penstock would bifurcate into smaller 8.5-foot-diameter penstocks,which
would connect to the powerhouse.
Construction access to the water conductors would be via the 20-foot-
diameter gate shaft,located approximately 500 feet south of the entrance
portal,as well as by access from the powerhouse excavation.Additional
access would be provided by two construction access tunnels.One access
tunnel,6000 feet long,would intersect the main power tunnel approximately
6.7 miles downstream from the inlet portal.A second tunnel,5300 feet long,
would provide access to the surge tank from the southeast.These construction
features are illustrated in Figure 2.1.
2.2.4 Power Plant
The powerhouse would be a semi-outdoor surface installation,located on
the north bank of the McArthur River about 25 miles upstream of the mouth of
the McArthur River on Cook Inlet.It will set into a side hill excavation and
will be anchored to the rock slope to provide additional resistance against
seismic forces.The structure would be reinforced concrete,and would be
approximately 120 feet wide,320 feet long,and 120 feet high (see Figures 2.4
and 2.5).It would contain four unit bays and a service bay.The unit bays
would house four vertical Francis turbines,each with an output of 166,000
horsepower under a net head of 869 feet,resulting in a total installed plant
capacity of 480 ,000 kW.The total pl ant di scharge under these conditi ons
would be about 7800 cfs.Generators would be umbrella-type,operating ata
2.18
iii"hi ..
~_.,t•.•J.,2•...•1211..a.aIlE.LL.b•..111_.;1I11111IilllLll:'21111bILIU'Ulkl':I",.,.•!._ttJ US
320'
PLAN AT EL.~06
......
-.,.
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DRAFT TUBE
ACCESS GALLERY
-1..
TYPICAL PLAN AT
<t DISTRIBUTOR EL.176
NSTOCKI---i PE
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I~PLAN AT ACCESS
~GALLERIES
......
-.,.
C\l
STORAGE
ROOM
AUXILARY RELAY ROOM
80'J~
I
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/ \o ",./TURB INE '....
"FLOOR--~EL.189~
PLAN AT.EL.189
.
,I
II
II
II
II
II
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......
-..,
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-~..l..-.....-~~L.--~"-----
DRAFT TUBE ~60'
SLOT
FIGURE 2.4.Powerhouse Plan 2.19
i
~h
38'-6 3S-6
NORMAL TAILWATER
EL.185 ~
ag;::::.....=~==H'
EL.244
8-05-0
350t CAPACITY CRANE
EL.254
..c:::::l.[.._,.._--.'----'
:36-0 I
Id-o
60'-0
·EL 206.::.:-""-:..,")':~..'/..-.."';..
VALVE PIT
ACCESS GALLERY
EL.186
SECTION THRU CENTER-LINE OF UNIT
NOT TO SCALE
FIGURE 2.5.Powerhouse Section
2.21
--~"';;---~-_.._--_..-...._---------------------_..._---------
'"
speed of 300 rpm.Turbine shutoff valves (either butterfly or spherical
valves)capable of operating under emergency shutdown,would gUffird each unit .."
Two main 260 MVA three-phase transformers would transform the voltage
from 13 kV to 230 kV transmission voltage.A two bay,one and a half breaker"
switchyard,containing six breakers and measuring approximately 300 feet long
by 100 feet wide,would be located adjacent to the powerhouse.
A tailrace channel with an average width of 200 feet would be excavated
to the natural river channel from the downstream end of the powerhouse draft
tubes.Draft tube gates would be serviced by a monorail hoist.The average
tailwater elevation is estimated to be elevation 185 feet.
2.3 TRANSMISSION SYSTEM
Previous studies of the Chakachamna project have considered various
alternatives for transmission line routes from the powerhouse to Anchorage.
The 1962 Bureau of Reclamation Status Report (USBR 1962)on the Chakachamna
project proposed 113.5 miles of 230-kV transmission lines with 1.5 miles of
submarine cables to be used to cross Cook Inlet near Anchorage.A 138-kV line,
presently being upgraded to 230 kV,now exists from Anchorage to the Beluga
Station of the Chugach Electric Association.The station is located about
40 miles east of the Chakachamna powerhouse.This transmission line is owned
and operated by the Chugach Electric Association.Therefore,only about
55 miles of new transmission line corridor have to be developed to extend from
the Chakachamna powerhouse to the Beluga Station.Any additional transmission
line required to deliver power from the Chakachamna Project to Anchorage will
likely utilize the corridor of the existing Chugach line.
Two possible routes (A and B)for the transmission line segment from the
Chakachamna power plant to the Beluga Station have been established through an
evaluation of topographic and geologic maps of the region.These routes are
shown in Figure 2.3.Route A is slightly longer than Route B by about
2 miles;however,foundation conditions appear to be more favorable for the
longer Route A and therefore Route A is recommended.
2.23
!~;'.
If
l ~l,
Basically,an overhead line will start in the switchyard close to the
powerhouse and head eastward just above the flood plain of the McArthur River
for approximately 7 miles.At this point Routes A and B differ.Route A
turns in a northerly direction for 2 miles,paralleling the eastern edge of
the Tordrillo Mountains before heading north eastward 5 miles to a crossing of
the Chakachatna River.Route B takes a more direct path to the Chakachatna
River,approximately 6 miles across low lands and swampy terrain.The pre-
ferred transmission corridor (Route A)will closely parallel the plant access
road right-of-way,as shown in Figure 2.3.
The transmission lines will then cross the Chakachatna River near its con-
fluence with Straight Creek.The crossing will be above ground and in close
proximity with an existing access road bridge crossing.From the Chakachatna
River crossing the transmission corridor will parallel an existing road for
approximately 40 miles to the Beluga Station.
Selection of transmission line structures is based on strength require-
ments,terrain,and visual appearance.Towers and angle structures will be
composed of tubular steel-guyed columns,60 to 90 feet high and pin-connected
to the foundation.These structures combine the necessary strength with an
inconspicuous appearance and will be economical to construct in rugged terrain
due to their unique anchoring methods.The ruling span for most of the line
would be 1000 feet.Approximately 10 percent of the structures will be
founded on rock and will require anchors to accommodate the uplift forces.
Ninety percent of the towers will be founded on deep soil deposits possessing
an active freeze-thaw zone.Steel H-pile foundations will be required for
these soil-supported structures.
~.4 SITE SERVICES
Site access will consist of an access road to the powerhouse as well as
an access road to the power tunnel intake (see Figure 2.3).A total of about
40 miles of road will be required to connect the site facilities with an
existing road crossing the Chakachatna River at its confluence with Straight
Creek.No pipeline,air,or waterway access will be required.During
constru9tion,electric power will be brought into the site from the nearby
2.24
....
Beluga Station.Living facilities during construction will be provided by
either a trailer park-type arrangement,or by temporary housing at ~he
powerhouse location and tunnel inlet.
2.5 CONSTRUCTION
2.5.1 General Construction MethodS
The feature of primary importance and uniqueness,from a construction
point of view,is the 10.8-mile-long power tunnel.For the purpose of this
project evaluation,it is assumed that the tunnel will be excavated using two
tunnel-boring machines (TBMs),each working 3 shifts per day.It is felt that
this will result in the most expeditious performance of the work while
minimizing tunnel lining requirements,tunnel diameter,work crews,and
excavation spoil.
Both TBMs will start from the central construction adit (see Figure 2.1)
and excavate in opposite directions towards the ends of the tunnel.The
upstream machine will excavate to within approximately 50 feet of the tunnel
outlet and then be dismantled in the tunnel.It would subsequently be removed
via the gate shaft shown in Figure 2.1.The tunnel will have to be locally
widened in the area where the machine is to be dismantled to provide access.
The last upstream 50 feet of the tunnel will be excavated by conventional
drilling and blasting after the entire tunnel is completed and the powerhouse
is nearly complete.
The second TBMwill work downstream towards the surge tank.It would
subsequently be removed from the tunnel via the access adit that enters the
surge tank area shown in Figure 2.1.
All other rock excavation,e.g.,for the surge tank,vertical shaft,
penstocks,emergency spillway,and bifurcations,as well as the powerhouse and
tailrace open cuts,and all construction adits,will be performed using
conventional drilling and blasting methods.It is envisioned that this
additional excavation (with the exception of the central adit)will be
performed concurrently with the main tunnel excavation.
2.25
itf.
i;~
i~
f
\J'
the
The powerhouse will be conventional in size and location,and should
therefore not require any unusual construction methods or techniques.The
only special consideration is the harsh winter climate,which will shorten
powerhouse construction year by approximately 4 months,particularly during
its earlier stages of construction.To compensate for this,extended work
shifts may be utilized in the summer months.
The transmission corridor is quite lengthy,utilization of the existing
Beluga corridor notwithstanding.In excess of 100 miles of transmission lines
will have to be provided;however,access will not be a problem.The corridor
will parallel existing or newly constructed roads.It is estimated that
several work crews can be utilized concurrently to erect the transmission
facilities from several locations.
2.5.2 Construction Schedule
A complete project schedule from preliminary field studies through
licensing,design,construction,startup testing,and commercial operation is
presented in Figure 2.6.The schedule is broken down by major project
activities versus calendar months;month zero representing July 1 of the base
year.
From the start of work authorization at month zero it is estimated that
approximately 18 months will be required to perform the preliminary field and
office work necessary to support the conceptual engineering and licensing
efforts.Part of this work will consist of performing field surveying and
mapping,as well as preliminary geotechnical,hydrologic,and environmental
studies.These efforts will utilize existing published information,as well
as data gathered through preliminary-level field work.
Conceptual engineering will be performed concurrently with the field
studies and will identify and evaluate possible alternative project layouts
and features that best util ize the water resources in the Chakachatna River
drainage basin.Power production analyses will consider a range of
operational alternatives and installed capacities to define an optimal plant
size and operation scheme.The selected plant size and operation scheme will
maximize pow~r output benefits and also incorporate any identified
2.26
.li i laliiiB llUlldii!ittJC22i!!L i.JJUL lULl::H LUCU2iiJ Ljj;:
o
JUL I
-\-JAN I---.-
---CALENDAR YEARS I I 2 I 3 I 4 I 5 I 6 I 7 I a I 9 I 10
---CALENDAR MONTHS----0 6 12 18 24 30 36 42 48 54 60 66 72 78 84 90 96 102 108 114 12
WORK ACTIVITY ,
I PRE CONSTRUCTION FIELD I
STUDIES
SURVEYING a MAPPING
GEOTECHNICAL'(PRELIMINARY)
ENVIRONMENTAL'(PRELIMINARY)
HYDROLOGIC STUDIES I---
CONCEPTUAL ENGINEERING
-Review of License Application •IT LICENSING ~---------------------
ill DESIGN A
GEOTECHNICAL ENGINEERING·(FINAL)
DETAILED ENGINEERING DESIGN
AND SPECIFICATIONS
!-
nt PROCUREMENT
-J
GENERATING EQUIPMENT «
~-0
y.CONSTRUCTION -t(
ACCESS ROADS a:::
I
w
ACCESS ADITS FOR TUNNEL a.
CONSTRUCTION
I
I 0
TUNNEL a SURGE TANK EXCAVATION
POWERHOUSE AND PENSTOCK
EXCAVATION IPENSTOCKS
POWERHOUSE -r
I
SWITCHYARD I
TRANSMISSION LINES -
:2I START UP AND TESTING
FIGURE 2.6.Project Schedule
2.27
am
'"
environmental constraints on project operation (e.g.,restrictions on drawdown
of Lake Chakachamna,instream flow requirements in the Chakachatn~river,and
restrictions to fluctuations in plant discharge into the McArthur River).
Included in this level of engineering will be a more detailed development of
transmission line routes,with emphasis given to routing the line clear of as
many natural hazards as possible.
The above IS-month effort will terminate with the preparation and sub-
mittal of the necessary documentation for a FERC license application.For
schedule estimating purposes,it is assumed that 2 years will be required for
processing of the license application by the FERC.(If significant opposition
to the project materializes the licensing phase may extend to as many as
4 years).
Upon submittal of the FERC license application,detailed design will
commence for the power plant and conveyance systems.This will also include
design of the structures and the mechanical,electrical and control systems,
as well as provision of support services to assure that the work is performed
with appropriate management controls and that materials are available to sup-
port project schedules.Specifically,this work will include the following:
•Preparation of detailed design criteri a for use in the development
of project design drawings.Design drawings will accommodate all of
the construction-related activities required by the project.This
includes solicitation of bids for services,construction and erec-
tion activities as well as actual construction of the tunnel,power-
house,and transmission facilities.In addition to the detailed
design drawings,the architect/engineer will prepare bills of
material for supply of miscellaneous electrical,mechanical,and
civil materials.
•Performance of engineering calculations required for preparation of
drawings,specifications,and other pertinent data used in the design
of the project,consistent with the requirements of regulatory bodies
and design codes and standards.
2.29
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.1
,II
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j
j
IiiII
I
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......
M
•Preparation of technical specifications in sufficient detail to allow
for project procurement and/or construction.
•Review of vendor documents and drawings for conformance to architect-
engineer (AE)-prepared specifications and for confirmation of phys-
ical interfaces with related systems.
•Establishment of quality assurance requirements based on the detailed
design developed on the basis of the project description,performance
calculations,as well as on information provided by vendors and con-
tractors.These requirements will serve as a basis for construction
and for erection of structures,for procurement,and for installa-
tion,testing and operation of equipment.
It is estimated that 2 years will be required to carry out these design
efforts from the time of formal receipt of the FERC license.
Procurement activities will run concurrently with detailed design and
will consist of the following:
•Preparation of bid documents and evaluation of bids.
•Monitoring and control of procurement contracts.
•Vendor quality assurance services to assure that purchased items are
supplied in accordance with the requirements of applicable procure-
ment documents.
•Expediting services to assure the timely arrival of purchased items
at the site.
Construction activities will commence in the summer about midway through
the design period and will consist of the start of access road construction,
connecting the site with the Chakachatna River crossing.It is estimated that
construction of the entire project can be accomplished in about 5 years from
the start of access road construction.As shown on the project schedule
(Figure 2.6},this estimate is based on the yearly cessation of outdoor con-
struction activities for a 3-to 4-month period during the winter months.
2.30
---------_._--_..,-,._.."._,....••I~~.-7"'1
""-
Indoor activities such as tunnel and penstock construction will,however,be
performed throughout the year.'\~
As discussed previously,the long tunnel is a unique construction feature
of the project and could be a critical path item in the construction of the
entire project.Therefore,it is assumed that work on the tunnel will be
performed year-round,three shifts per day using two tunnel-boring machines
simu1tanteous1y.Due to the length of the transmission line,it is also
assumed that work will proceed on it from several locations simultaneously.
Startup testing of all major equipment and auxiliary appurtenances will
be performed before commercial acceptance.This testing will start during the
last year of powerhouse construction and will continue for a period of
approximately 4 months after construction has been completed.
The total design and construction period including preconstruction fie1a
studies,design,licensing,construction and startup would be approximately
9~1/2 years.A mid-1982 authorization to proceed(a)wou1a result in a fully
operational facility about the end of 1991.
2.5.3 Construction Work Force
The number of workers necessary for construction of the project will vary
over the approximate 5-year construction period.The distribution of this
work force over the schedule is shown in Figure 2.7.Construction is
estimated to peak near the end of year 3,requiring a work force of
approximately 1220 personnel.
2.6 OPERATION AND MAINTENANCE
2.6.1 General Operating Procedures
The Chakachamna project will be operated as a conventional hydroelectric
facility,with releases being made through the power plant on a daily basis as
required to meet load demands.The project will ordinarily operate 24 hours a
day,with the greatest release being made during daytime periods of peak
load.During off-peak periods,the plant discharge will vary depending on
(a)Used as a basis for comparison in this series of studies.
2.31
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50
I?()O
So
1100
54
/(){)(}
S(}
fa1
50
8f}O
SO
~7(x)~50
~'00
~SO~.1'00
~So
-I(JO
so
Joo
50
2
O-+--r-T"""""~""""""T'....,..-r-~"""-~T""""'"1r--T--r---.-...,.--r--r-T""""'"1r--T-..,......,.....,.--r-.....-..-......,---r...l--
~24~8MMU~~.nU~~.nUUM.Mu~n~Q~Q~U
MONTHS
NOTE:Oo~s not include v,,,dor pe,..so~",,~1-o,wner personAe/,A-£~Ag/nt!"erS'.
or rro/1.S"mi,ssion Iti?e cansfrwt:f!o/7 l'e/'sOA/le//ocafec'af ..sife.
FIGURE 2.7.Construction Work Force Requirements
local characteristics but will never fall below a minimum discharge require-
ment.The reservoir level would vary on a seasonal basis as a function of
load characteristics and availab1e streamflow.The details of the operating
characteristics are discussed in greater detail below.
2.6.2 Operating Parameters
Forced Outage Rate
The estimated forced outage rate for the project is 1 percent.
Scheduled Outage Rate
The s~Heduled outage rate for the plant is estimated to be an average of
5 days per year per unit over the life of the project.
2.32
iEtJjjj .&!!L ....jj t h1 11I11I iLl tUX 21JLLJiiii!liJUSSi 11
~.
Power Output and Project Operat i onCharacteri sti cs
A hydropower simulation study was performed for:the Chakachamna project
by Acres American,Inc.(1981).This study involved utilization of a
reservoir and power plant simulation model that simulated the operation of the
project on a monthly basis for the 13-year period of hydrologic record.The
results of this study were obtained from Acres and reviewed by Ebasco.To
provide an independent check to the Acres study,Ebasco performed a similar
operation study using the 13-year record of streamflow at the lake outlet as
inflow.As discussed below,the assumption will introduce some error into
certain study results.Several parameters used in Ebasco's simulation study
were obtained directly from the Acres study.These include storage-elevation
data,maximum and minimum operating storages,average tailwater level,minimum
powerhouse release requirements,monthly demands,load factor,the discharge
coefficient,and average overall efficiency.The results of Ebasco's
operation study have been utilized herein as a basis for estimating the power
output and operation characteristics of the project.
During an average hydrologic year,the reservoir level will vary between
the normal maximum level of elevation 1127 feet and a minimum of elevation
1019 feet,with the average reservoir level being elevation 1076 feet.The
estimated average tailwater level at the McArthur River of the powerhouse site
is elevation 185 feet.The resulting average net power level (including
allowance for friction losses in power conduit)is estimated to be 867 feet.
Table 2.3 represents the estimated operational characteristics of the project
during an average hydrologic year,showing the anticipated monthly values of
generation and reservoir level.These values are obtained from the results of
Ebasco's simulation study for the period of hydrologic record.The estimated
average annual energy production from the project is 1,892 GWh,which
corresponds to an annual plant factor of 45 percent.The firm annual energy
is estimated to be 1,869 GWh.
It should be noted that utilization of the recorded outflows at Lake
Chakachamna as inflows into the reservoir in the operation studies will result
in some error,because the recorded outflows are subject to the natural
regulatory effect of the lake.Utilizing t~e recorded outflows as inflows in
2.33
&
TABLE 2.3.Project Operation During Average Hydrologic Year
Average Month ly Average End-of-Month
Energy Generation Reservoir Elevation
Month (GWh)(ft)
October 166 1112
November 184 1102
December 207 1088
January 191 1075
February 163 1062
March 162 1047
Apri 1 140 1032
May 133 1019
June 124 1034
July 126 1075
August 137 1108
September 159 1116
Annual Average 1892 1076
the operation study will admittedly have negligible effect on the estimate of
average annual energy,but the firm energy will tend to be overstated,since
the actual inflows during the driest year of record would be less than the
outflows recorded at the outlet of the lake.Therefore,the actual firm
energy available from the project would be less than the 1,869 GWh obtained
from the operation studies.Any further operation studies should use
reservoir inflows that have been computed by adjusting the recorded outflows
for the effect of storage in the lake.
The plant discharge into the McArthur River will vary from a maximum of
approximately 8,100 cfs,under conditions of maximum reservoir level and power
output,to a minimum of 1000 cfs during offpeak hours.The naturally
occurring discharges from Lake Chakachamna into the Chakachatna River will be
,essentially eliminated.
2.34
tLXii .J 2 LtJ.Jl i LJ12iLL JJ2L2iiJU£L:"UJJliitJii$i USJlIIbSd22LnUS:dllUlU_·Uea
'"
It should be noted that the simulation study results described above are
based on the assumption that all of the available inflow into Ch~k'achamna Lake
would be diverted to the powerhouse on the McArthur River,with no downstream
fish release being provided in the Chakachatna River below the lake.This,of
course,represents the most optimistic assumption regarding available flows
for power generation.If a fishery maintenance release were provided in the
Chakachatna River downstream of Chakachamna Lake,both the firm ana average
annual energy production from the project would be reduced.Whether the proj-
ect would be feasible with a .fish release requirement can only be evaluated by
estimating the power output and resulting cost of power associated with the
selected fish release schedule.The project construction cost estimate for
such a scheme would have to include an allowance for flow control facilities
at the outlet of Chakachamna Lake that would be capable of reliably releasing
the desired amount of water.
2.6.3 Project Life
The economic life of the project is considered to be 50 years.
2.6.4 Operating Work Force and General Maintenance Requirements
It is anticipated that the Chakachamna project will be a remote-
controlled facility and will not require resident operating personnel.Daily
trips will,however,be made to the plant to perform routine maintenance and
inspection.These inspections could be performed by one or two operators.
Major overhauls and maintenance work will ordinarily be performed on an annual
basis by a larger crew.
Although the presence of rock flour in the reservoir water may cause some
additional wear to the turbine parts,major components of the generating
machinery are not expected to need replacement during the life of the proj-
ect.Repairs to the runner blades are likely and certain parts of the
turbine may have to be replaced during the turbine life,such as bearings,
wicket gates,wear rings,and face plates.Generator bearings and windings
are other items that may have to be replaced during the plant life.In
addition,many pieces of auxiliary or supporting equipment may have to be
replaced at least once during the project life.As frequently is the case,
2.35
~:rrj
__.1 .4
'r'
this may,however,be caused by the equipment item having become obsolete and
replacement parts not being available.Replacement is then often less costly
than fabricating special parts.
2.36
tnlPI·nrm 'rrrn;··'-I
.....
3.0 COST ESTIMATES
,}
-....,:
3.1 CAPITAL COSTS
3.1.1 Construction Costs
Construction costs have been developed for the major bid line items com-
mon to hydroelectric power plants.These line item costs have been broken
down into the following categories:labor and insurance,construction sup-
plies,equipment repair and labor,equipment rental,permanent materials,and
subcontracts.Results of this analysis are presented in Table 3.1.Total
overnight construction cost is estimated to be $1,010 million.(a)The equiva-
lent unit capital cost is ~2104 per kilowatt.
3.1.2 Payout Schedule
A payout schedule has been developed for the entire project and is pre-
sented in Table 3.2.The payout schedule was based on a 60-month basis from
start of project construction to completion.
3.1.3 Escalation
Estimates of real escalation in capital costs for the plant are presented
below.These estimates were developed from projected total escalation rates
(a)January 1982 dollars,not including land or land rights,owner's costs or
transmission costs beyond the switchyard.
3.1
·n:
"TABLE 3.1.Bid Line Item Costs for Chakachamna Hydroelectric Project{a)
(January 1982 Dollars)
Construction Equi pment
Labor and Construction Repair Equipment Permanent Sub-Total
Bid Line Item Insurance Supplies Labor Rent Materials Contracts Di rect Cost
1.'Improvements to Site 224.800 11,300 232,500 173,300 6,900 648,800
2.Earthwork and Piling 67,632,100 35,994,400 21,749,000 56,307,000 160,256,100 680,000 342,618,600
3.Concrete 29,666,200 1,201,900 4,621,900 2,973,300 17,864,400 56,327,700
4.Structural Steel and Lift Equipment 2,238,200 348,500 97,400 925,400 10,985,000 14,594,500,5.Bui ldi ngs 263,400 28,800 12,000 477 ,000 781,200
6.Turbine Generator 6,684,000 46,000 20,000 62,000,000 68,750,000
7.Other Mechanical Equipment 362,600 23,000 9,000 1,175,000 1,569,600
8.Pi pi ng 1,966,200 40,300 20,000 3,000,000 5,026,500
9.Instrumentation 93,500 3,500 1,500 100,000 198,500
10.Electrical Equipment 2,803,600 40,300 30,000 4,500,000 7,373,900
w 11.Painting 201,200 17 ,300 10,000 125,000 353,500.
N 12.Off-Site Facilities 9,227,700 834,700 15,500,700 11,654,600 2,438,200 39,655,900
13.Substation 670,700 23,000 15,000 2,100,000 2,808,700
14.Const ruct i on Camp Expenses 9,791,400 36,700,700 46,492,100
15.Indirect Construction Costs a~d
Architect/Engineer Services(b 134,277,800 22,730,500 5,201,100 2,723,000 ---164,932,400
SUBTOTAL 266,103,400 98,044,200 47,402,600 74,874,100 265,027,600 680,000 752,131,900
Contractor's Overhead and Profit 129,000,000
Contingencies 129,000,000
TOTAL PROJECT COST 1,010,131,900
(a)The project cost estimate was developed by S.J.Groves and Sons Company.No allowance haS been made for land and land rights,client
charges (owner'S administration),taxes,interest during construction or transmission costs beyond the substation and switchyard.
(b)Includes :i98,OOO,OOO for en9ineering services and :i66,932,400 for other indirect costs including construction equipment and tools';
construction related buildings and services,nonmanual staff salaries,and craft payroll related costs.
·""•.,i,WI r··1m',.r ····;i 7n Ii!IInns 1r -•
'"
.J
TABLE 3.2.Payout Schedule for Chakachamna Hydroelectric System
(January 1982 dollars)
".;j'
Month
l.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
2l.
22.
23.
24.
25.
26.
27.
28.
29.
30.
31.
32.
33.
34.
35.
36.
37.
38.
39.
40.
4!.
42.
43.
44.
45.
46.
47.
48.
49.
50.
5!.
52.
53.
54.
55.
56.
57.
58.
59.
60.
Cost per Month,
Dollars
8,165,100
8,165,100
10,447,900
10,447,900
10,447,900
10,447,900
10,447,900
10,447 ;900
8,165,100
8,165,100
8,165,100
8,165,100
8,165,100
11,498,900
11,498,900
11,498,900
11,498,900
11,498,900
11,498,900
11,498,900
11,498,900
11,498,900
8,165,100
8,165,100
8,165,100
13,714,100
13,714,100
13,714,100
13,478,800
13,478,800
13,478,800
13,478,800
13,478,800
15,316,400
13,145,000
25,570,100
22,427,800
24,082,900
24,082,900
31,490,600
34,680,400
35,262,800
35,262,800
35,262,800
31,859,100
36,715,500
31,870,500
32,261,800
17,572,800
21,170,800
21,170,800
21,170,800
21,170,800
20,230,600
20,230,600
20,692,100
18,463,400
18,463,400
14,791,700
9,347,900
3.3
Cuinul at;ve Cost,
Dollars
8,165,100
16,330,200
26,778,100
37,226,000
47,673,900
58,121,800
68,569,700
79,017,600
87,182,700
95,347,800
103,512,900
111,678,000
119,843,100
131,342,000
142,840,900
154,339,800
165,838,700
177,337,600
188,836,500
200,335,400
211,834,300
223,333,200
231,498,300
239,663,400
247,828,500
261,542,600
275,256,700
288,970,800
302,449,600
315,928,400
329,407,200
342,886,000
356,364,800
371,681,200
384,826,200
410,396,300
432,824,100
456,907,000
480,989,900
512,480,500
547,160,900
582,423,700
617,686,500
652,949,300
684,808,400
721,523,900
753,394,400
785,656,200
803,229,000
824,399,800
845,570,600
866,741,400
887,912,200
908,142,800
928,373,400
949,065,500
967,528,900
985,992,300
1,000,784,000
1,010,131,900
~j;
(including inflation)and subtracting a Gross National Product deflator series
which is a measure of inflation.
3.2 OPERATION AND MAINTENANCE COSTS
Estimated real escalation of operation and maintenance costs is as
follows:
Escal at ion
Year (Percent)
1981 1.5
1982 1.5
1983 1.6
1984 1.6
1985 1.7
1986 1.8
1987 1.8
1988 2.0
1989 2.0
1990 2.0
1991 2.0
3.3 COST OF ENERGY
The estimated busbar energy cost for the Chakachamna hydroelectric proj-
ect is 25.5 mills per kilowatt-hour.This is a levelized lifetime cost,in
January 1982 dollars,assuming a 1991 first year of commercial operation and
full utilization of the average annual power output of the facility.Esti-
mated busbar energy costs for lower capacity factors and other startup dates
are shown in Figures 3.~and 3.2.First and subsequent year energy costs and
capital a'1d:'O&M cost components are shown in Table 3.3.Year-of-occurrence
3.4
"'II JXj i;.d!bid iii !bILl J iLLJ
".'..;'...,.,..U parn TEH --J
...
100
60
40
20
~i j
oJ:
~I-!!
Os 80-....
IIIo
U
>
(.:J
0::w
Zw
0::«
CO
III
;:)
CO
Cl
W
N
...J
W>W
...J
Cl
W....«
:2
....
III
W
o
o 20 40 6~
CAPACITY FACTOR (%l
80 100
FIGURE 3.1.Cost of Energy Versus Capacity Factor
(January 1982 dollars)
costs are essentially flat over the economic lifetime of the facility,since
O&M costs represent a small portion of the total costs.
These costs are based on the following financial parameters:
Debt Financing
Equity Financing
Interest on Debt
Federal Taxes
State Taxes
Bond Life
General Inflation
100%
0%
3%
None
None
50 years
0%
3.5
.--
100
60 I--
80 I--
40 r--
FIGURE 3.2.Cost of Energy Versus First Year of Commercial
Operation (January 1982 dollars)
2005
I
2000
I
1995
YEAR OF FIRST COMMERCIAL OPERATION
I
1990
o
20 f--
.-
.I:.
==,:,t,--~
's
J-
til
0
U
>
t.:lc::wzw
c::
e:(
OJ
til
~
al
Cl
W
N
...J
W>W
...J
Clw
l-
e:(
:;;
~J-
til
W
~
I
i~
"~
)
The escalation factors given in Section 3.1 were employed.Weighted average
capital cost escalation factors were derived using a labor/material ratio of
30 percent/lO percent.
3.6
1Nt1l1:1II:1I:•._m.iJ••:.aZII,IIJII,,"o,lItll,_til'.'.L.":lIli,II,JII"IILL.L.UlilUI.iLI,lIIJ.allll.LIJIilLI.••t.U.X.ki.lIU22,.........--.
r t1r nT1CmnnrWTrin r T 7ti ·7 •••••I •
j
'"
TABLE 3.3.Year-of-Occurrence Energy Costs (January 1982 dollars)
~<
Unit Unit Un it'!
Capi ta 1 Costs O&M Costs Total Costs
Year (mi 11 sl kWh)(mill s/kWh)(mills/kWh)(a)
1991 23.8 1.1 25.0
1992 23.8 1.2 25.0
1993 23.8 1.2 25.0
1994 23.8 1.2 25.0
1995 23.8 1.2 25.1
1996 23.8 1.3 25.1
1997 23.8 1.3 25.1
1998 23.8 1.3 25.1
1999 23.8 1.3 25.2
2000 23.8 1.4 25.2
2001 23.8 1.4 25.2
2002 23.8 1.4 25.2
2003 23.8 1.4 25.3
2004 23.8 1.5 25.3
2005 23.8 1.5 25.3
2006 23.8 1.5 25.4
2007 23.8 1.6 25.4
2008 23.8 1.6 25.4
2009 23.8 1.6 25.5
2010 23.8 1.6 25.5
2011 23.8 1.7 25.5
2012 23.8 1.7 25.6
2013 23.8 1.8 25.6
2014 23.8 1.8 25.6
2015 23.8 1.8 25.7
2016 23.8 1.9 25.7
2017 23.8 1.9 25.7
2018 23.8 1.9 25.8
2019 23.8 2.0 25.8
2020 23.8 2.0 25.8
2021 23.8 2.1 25.9
2022 23.8 2.1 25.9
2023 23.8 2.1 26.0
2024 23.8 2.2 26.0
2025 23.8 2.2 26.1
2026 23.8 2.3 26.1
2027 23.8 2.3 26.1
2028 23.8 2.4 26.2
2029 23.8 2.4 26.2
2030 23.8 2.4 26.3
2031 23.8 2.5 26.3
2032 23.8 2.5 26.4
2033 23.8 2.6 26.4
2034 23.8 2.7 26.5
2035 23.8 2.7 26.5
2036 23.8 2.8 26.6
2037 23.8 2.8 26.7
2038 23.8 2.9 26.7
2039 23.8 2.9 26.8
2040 23.8 3.0 26.8
(a)Rounding errors may be present.
3.7
SlTTT!r u
-..,--.I
4.0 ENVIRONMENTAL AND ENGINEERING SITING CONSTRAINTS
''rC'
Council of Environmental Quality regulations implemented pursuant to the
National Environmental Policy Act of 1969 require that an environmental impact
statement be prepared for projects requiring licensing by a federal agency.
The statement must include a discussion and evaluation of alternatives to the
proposed action.This requirement is usually satisfied for hydroelectric
projects through the evaluation of alternative sites (projects)and possibly
through the evaluation of other energy-generating technologies.The purpose
of such a siting study is to identify a preferred project and possibly viable
alternative projects to supply the required amount of power.This process can
contribute to reductions in project costs,through analysis of environmental
and engineering siting considerations.
This section presents many of the constraints that will be evaluated dur-
ing a siting study.Special attention is given to the applicability of these
constraints to the location considered in this study.It should be realized
that many of the constraints placed upon the development of a hydroelectric
plant are regulatory in nature and therefore the discussion presented in this
section is complemented by the identification of power plant licensing
requirements presented in Section 6.0.
4.1 ENVIRONMENTAL SITING CONSTRAINTS
4.1.1 Water Resources
Water resource siting constraints generally center about two topics:
water availability and water quality.With a hydroelectric project,there are
additional locational constraints placed upon the water resource,e.g.,loca-
tional suitability of the reservoir formed by the project.The Chakachamna
project presents a variation in that a natural reservoir (lake)already exists,
and evaluations would need to be made on impacts from changes on lake level to
the local hydrology.
The dewatering of the upper portion of the Chakachatna River may preclude
the project development unless this environmental cost is deemed acceptable.
Alternatively,controlled discharges could be made to the Chakachatna River to
4.1
p
support the anadromous fishery.The tailrace discharges to the McArthur
may result in water changes to this river system,which again would need
considered in a feasibility study.
4.1.2 Air Resources
River
to be
There will be no major environmental impact or siting constraints relat-
ing to air resources.
4.1.3 Aquatic and Marine Ecology
A detailed inventory of the aquatic species and habitat characteristics
present in Lake Chakachamna,the Chakachatna River,and the McArthur River
will need to be performed,with emphasis on andromous fish,significant
benthos,and aquatic vegetation-supporting terrestrial life.Changes in the
populations of these species due to the drastic changes in the hydraulic
regimes must be estimated and weighed in the feasibility study,to ascertain
if the project benefits outweigh potential environmental costs.
4.1.4 Terrestrial Ecology
Since habitat loss is generally considered to represent the most signifi-
cant impact on wildlife,the prime study activity regarding terrestrial ecology
will be an identification of important wildlife areas,especially critical
habitat of threatened or endangered species.Based upon this inventory,exclu~
sion,avoidance and preference areas for tunnel access points,access roads,
and other components that do not require a specific location should be deline-
atea and factored into the overall plant component siting process.Habitat
losses due to the anticipated changes in river morphology for such important
species as moose,caribou,and black bear need identification and evaluation
in the feasibility study.
4.1.5 Socioeconomic Constraints
Major socioeconomic constraints center about potential land use conflicts,
and community and regional socioeconomic impacts associated with project activ-
.ities.Potential exclusionary land uses will include lands set aside for
public purposes,areas protected and preserved by legislation (federal,state
4.2
$j.k2ill.)j~!Ud~
tlttli 11 "enor,I!II '-pm r Tn n rrn;lin Itt l'ppm •-J
or local laws),areas related to national defense,areas in which a hydroelec-
tric installation might preclude or not be compatible with local;activities
i/-
(e.g.,urban areas or Indian reservations),or those areas presenting safety
considerations (e.g.,aircraft facilities).Avoidance areas will generally
include areas of proven archeological or historical importance not under
legislative protection,and prime agricultural areas.
Regarding other socioeconomic concerns,minimization of the boom/bust
cycle will be a prime criterion.Through the appl ication of criteri a per-
taining to community housing,population,infrastructure and labor force,this
important consideration should be evaluated anu preferred mitigative measures
identified.Because the potential power plant area is a remote site and will
likely cause significant boom/bust-related impacts on nearby small population
communities (i.e.,Tyonek),socioeconomic criteria will be heavily weighted in
the overall site evaluation process.
4.2 ENGINEERING SITING CONSTRAINTS
The Chakachamna site has some characteristics that could constrain the
development of the project.These include seismic,volcanic,glacial,and
hydrologic aspects.
The Lake Clark-Castle Mountain fault passes within 11 miles of the site
and is known to have been an earthquake generator.It is estimated that a
potential magnitude-seven earthquake can occur along this feature.An earth-
quake of this size can be adequately designed for but will require more costly
and massive structures.Such an earthquake might also affect the stability of
the Barrier Glacier that forms Chakachamna Lake.This could cause a potential
hazard downstream of the project.
The close proximity of the Lake Clark-Castle Mountain fault to the site
increases the possibility that other faults may be present along the route of
the power tunnel.To verify the existence of any such faulting,an aero-
magnetic survey should be conducted along the power tunnel alignment.The
survey should cover a distance of at least 5 miles outward along each side of
the alignment.The results of the survey would be interpreted to yield
magnetic contours to delineate the configuration of the various granitic rock
4.3
..
formations along the tunnel route,as well as overburden thickness.The
presence of faulting (if any)would then be determined and subsequently
confirmed by local seismic refraction surveys.
Any faults confirmed would then be studied for capability by performing
mineralogical dating studies at a surface expression of the faults.An
alternative to the dating study is to assume that any faulting along the
tunnel alignment is capable and then to statistically determine,through
correlations with the Lake Clark-Castle Mountain fault movements and with area
seismicity,when the next movement along the fault could be anticipated.
Seismicity associated with this movement would also be determined.
Based on information currently available,it is felt that the presence of
faulting along the tunnel alignment should not alone preclude the feasibility
of the project.Seismic loading to the project facilities caused by this
movement could be incorporated into the design.Physical constrictions in the
tunnel that might develop due to movements along the fault could,if
significant enough,be repaired locally.Typically,however,movements and
offsets in tunnels traversing areas of high seismicity and faulting are small.
Mudslides,glowing avalanches (gases and solids flowing together in a
liquid),and ash falls from an eruption of the active Mount Spurr volcano
might similarly affect the stability of the Barrier Glacier,as well as the
operation of the power tunnel intake and any lake outlet structure/emergency
spillway that is provided.Mt.Spurr has a history of active ash eruptions,
with the most recent occurring in'1953.The 1953 eruption caused mUdslides
that temporarily dammed the Chakachatna River for a length of several miles
below Barrier Glacier.Ash falls can also be quite disruptive to the
operation of the switchyard and transmission lines,causing pole fires,
flashovers,and on occasion,trip-outs.Trip-outs,however,are more
predominant in non-vertical insulator arrangements.
Design precautions may be taken to mitigate some of the effects that
volcanic activity may have on the project.A potential ash fall depth should
be considered as an added.normal live load for the design of the powerhouse
and any othe.,r"plant facilities.Openings to the powerhouse should be kept to
4.4
..
'"
a minimum.Since the facility would be remote-controlled,no win.dows should
be provided.Equipment at the intake gate should be completely enclQ~ed.
Also,protective measures should be made available for workers at th"e site
(e.g,protective masks,air packs,etc.).
Specifications for the generating equipment should include requirements
for extra-durable runner and wicket gate seals.This will extend the life of
the seals against the errosive effects of volcanic ash suspended in the
water.In addition,special water filters should be provided for the unit
bearing lubrication systems to assure that this water remains clear.
The electrical transmission equipment will require special protective
features,especially since volcanic ash may contain chemical components that,
when in contact with water,will cause conducting films on the insulator
surfaces.Therefore,insulators will have to be selected that have increased
breakage distances and special anti-pollution shapes.In areas where ash
buildup is likely to be high,which may include the switchyard and portions of
the transmission line,additional preventative measures would have to be
provided.Such measures include periodic lubrication of the insulators with
silicone,hot-line washing of the insulators using a mobile hot-line washing
truck (in the sWitchyard only)and,where acceptable,de-energized washing of
insulators.
Mudslides and glowing avalanches previously mentioned should not affect
the powerhouse area due to the protective topography between Mt.Spurr and the
site.These events could,however,greatly affect Chakachamna Lake,its
outlet,and the power intake.The potential of a mudslide and/or glowing
avalanche filling a portion of Chakachamna Lake and inundating its outlet
and/or intake would have to be studied in detail.If these occurrences proved
highly probable,the entire lake-tap design concept,as it presently exists,
would have to be modified.A relocation of the intake structure several miles
to the west,and a corresponding increase in the tunnel length could be
required.If these events are significant enough to close the lake outlet,a
temporary outlet would have to be provided by channeling or some other means
until the existing outlet is reopened,or a new outlet constructed.
4.5
't%i'!!IF!t#'-,7tt '~1Ij&.c'_ii7~~"',_"",~,
- - -t
Finally,the operating agency of the project should take practical
measures to maintain a high level of awareness of the volcanic activity at
Mt.Spurr.If an eruption seems certain,the operators of the project should
be prepared to close the intake gates and shut down the plant on very short
notice.This course of action should be implemented if the eruption is
serious enough to significantly damage an operating plant,regardless of the
above design considerations.
The normal course of Barrier Glacier movements that will result from
withdrawing water from Chakachamna Lake may present some difficulties that
will need to be investigated.For example,the mitigating effect that power
production might have on the natural erosion of the glacier by the Chakachatna
River may cause the glacier to form a continuous ice dam across the outlet of
Chakachamna Lake.The potential problem of glacier movements will require a
detailed study into the mechanics and extent of these movements.
Also related to the glacier-ice dam concern is the potential effect that
a probable maximum flood (PMF)could have on the stability of the ice dam.If
such potential formation of a continuous ice dam was proved to be likely,the
emergency spillway would then have to be sufficiently large to accommodate the
PMF.
4.6
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~.li1J=-;;L.JJU!!!i§!lJiil\,LJW;~
""
5.0 ENVIRONMENTAL AND SOCIOECONOMIC CONSIDERATIONS
5.1 SUMMARY OF FIRST ORDER ENVIRONMENTAL IMPACTS
The construction and operation of the proposed Chakachamna hydroelectric
generating facility will create changes or impacts to the land,water,and
socioeconomic environments in which it is located.These impacts are directly
related to various power plant characteristics that represent the primary
effects of the plant on the environment.A summary of these characteristics
is presented in Table 5.1.In this section,the primary effects of the pro-
posed hydroelectric projec are analyzed and evaluated in light of existing
environmental conditions to determine the significance of the impact and the
need for additional mitigative measures.
5.2 ENVIRONMENTAL AND SOCIOECONOMIC EFFECTS
5.2.1 Water Resource Effects
The configuration of the hydroelectric project will have some signifi-
cant,irreversible impacts on the local water resources.Diversion of the
runoff into Lake Chakachamna to the ~lacArthur River via the proposed power
tunnel will essentially eliminate discharge from the lake into Chakachatna
River.In addition,under very dry hydrological conditions the lake will be
subject to fluctuations in elevation of up to 160 feet.The McArthur River
will expenience an increase in flow,corresponding roughly to the loss in the
Chakachatna River.Should the water qualities of the lake and McArthur River
differ significantly,the river will experience a charge in water quality as
well.
Parameters most likely to experience a change include temperature.dis-
solved oxygen,total dissolved gases,and suspended sediment.Adverse aquatic
impacts generic to most hydroelectric power plants and potential problems with
the Chakachamna project include stabilized flow patterns,armoring and scouring
of stream beds,reduced bedload movement,flushing,and high-pressure dis-
charges that could cause gas supersaturation.
5.1
r"Vo'""~-"~'''''"'''''~'f'''1Hf#HRI'"liIlU_IliJ~.II.n''•••I::······..el!!!.....•..~£!.'..'.•-.:='.I!!.II!I!£E•.I!.~.QII•••••••••••••_-------------__t -r-
TABLE 5.1.Primary Environmental Effects
No first order impacts.
Water
Diversion to McArthur
River Through Plant
Water Qual ity
Other
Aquatic and Mari ne Ecosystems
Anadromous Fish
Other
Terrest ri a 1 Ecosystems
Wil dl ife Habi tat
Food Chain
Human Presence
Rare and Endangered Species
Pl ant Site
Pl ant Access
Transmi ss i on
Relocations
Socioeconomic
Construction Work Force
Operati ng Work Force
Relocations
Land Use Changes
Recreation
Capital Investment
Operating Investment
Ave rage:3660 cfs
Maximum:8100 cfs
Minimum:1000 cfs
To be determined in siting and feasi-
bi 1 ity studies;impacts anticipated to
be changes in suspended sediment and
increases in dissolved gas concentration.
Fluctuation in lake level to 160 feet.
Probable destruction of existing sockeye
salmon run under proposed operating
regime.Potential impact on Chinook and
pink salmon runs of lower Chakachatna
and McArthur Rivers.
Likely impacts on lake trout,arctic
char,whitefish,rainbow trout,scul-
pins,blackfish and northern pike due to
changes in water qnl ity,flow regime or
lake-level fluctuations.
Changes in riparian vegetation,loss of
habitat at powerhouse,access road and
sites.
Effects of changes in fish population.
Increased access to McArthur and
Chakachatna River drainages and to
Chakachamna Lake.
No significant impact expected.
Modest (tens of acres).
Approximately 40 miles of road.
Approximately 55 miles of 270-kV
overhead 1 ine.
None.
Peak requirement of approximately 1220.
1-2 operators for daily inspection.
None.
Less of wilderness quality in Chakachatna
and McArthur River valleys;and in valley
of Chakachamna lake.
Loss of wilderness quality as above.
Increased access to Chakachatna and
McArthur River valleys and tQ
Chakachamna Lake.
65 percent within region
35 percent outside region.
89 percent wi thin region
11 percent outside region.
5.2 I
j
'"
5.2.2 Air Resource Effects
Since the reservoir (Lake Chakachamna)already e~ists,ther~are no
anticipated significant effects to the air resource or local climatology.
5.2.3 Aquatic and Marine Ecosystem Effects
Potential aquatic ecological impacts of hydropower project construction
on Chakachamna Lake center on lake level fluctuations as a result of reservoir
drawdown (exposure of fish spawn and elimination of spawning habitat)and
possible entrainment and impingement problems (fish eggs,larvae,and food
organisms)associated with diversion of lakewater through the turbines.
Potential aquatic ecological impacts to the lake inlet streams may result from
decreased lake access due to reservoir drawdown at certain periods of the year.
The primary inlet to the lake,the Chilligan River,serves as a spawning
area for red (sockeye)salmon.Known spawning areas for Chinook (King)and
pink (humpy)salmon exist in the lower tributaries of the Chakachatna and
McArthur Rivers.The McArthur River will receive the tailrace flows from the
project.The annual adult escapement for these species is unknown,as is
their contribution to the Cook Inlet runs.Lake trout are resident within
Lake Chakachama;Dolly Varden (Arctic char),whitefish,and rainbow trout are
present in .the lower tributaries of the Chakachatna and McArthur Rivers.
Information on anadromous species,including estimates of annual escapement,
are not available for these drainage areas.Non-salmonid fish species that
probably occur within project area waters include sculpins,blackfish,and
northern pike.It is highly likely that all of the above species will be
disturbed.
Aquatic impacts on the Chakachatna and McArthur Rivers will be the most
severe due to potential changes in existing flow regimes.For example,the
design will essentially dewater the upper Chakachatna River and divert the
lake outflow via a tunnel to the McArthur River.This operating scenario
would most likely eliminate anadromous fish access,to the upper Chakachatna
River and Chakachamna Lake and will alter the existing flow regimes and
chemical makeup of the McArthur River,thus potentially altering fish
production in that river as well.
5.3
It is possible that sockeye salmon runs blocked from entering Lake
Chakachamna via the Chakachatna River would enter the McArthur River,homing
to Chakachamna Lake water discharged at the powerhouse.
A thorough study of the numbers and species of fish and their habitat
requirements will be needed to assess potential mitigative measures for any
losses due to project construction and operation.Depending on the results of
this study,several types of mitigative measures could be used to offset any
projected losses.These measures include:1)maintenance of acceptable
streamflows (e.g.,in Chakachatna River)based on instream flow analyses;
2)trapping and transporting of both upstream and downstream migrants past
project facilities;3)screening of the intake;4)fish passage facilities
around dewatered areas;5)spawning channel s;6)new hatcheries at a number of
potential locations;and 7)indirect enhancement to commercial and recrea-
tional fisheries by enhancing resources in nearby rivers.Each alternative
measure will have to be weighed against cost and effectiveness in determining
the final one to be used.
5.2.4 Terrestri al Ecosystem Effects
The primary potential wildlife impacts of hydroelectric development in
the project area will be from riv'er level fluctuations and habitat loss.
River level fluctuation may change the character of the riparian vegetation
that is used by moose in the winter and marshes that are used by waterfowl
during the spring,summer,and fall.Changes in the river level may also
affect the fish populations utilized by brown and black bear and habitat used
by beaver.Unexpected drawdown will expose beaver inhabiting lodges to
predation.
In addition to these impacts,hydroelectric faci 1ities and access roads
will eliminate some wildlife habitat and open up the project area to increased
hunting pressure.While increased hunting is detrimental to some populations,
it is beneficial to others,and it provides additional hunting opportunity to
Alaskans.Increased access and the associated use by people will also create
more poa<;:,hing andhuman/bear conflicts.Project design will impact wildlife
in two r4ver drainages.However,wildlife impacts resulting from alteration
of Lake Chakachamna are expected to be small.
5.4
...
5.2.5 Socioeconomic Effects
The construction and operation of a large hydroelectric pla~f has a high
potential to cause a boom/bust cycle,causing significant impact on community
infrastructure.The site is located at or near communities with a population
of less than 500.Peak construction crew requirements of approximately 1220
workers will be necessary for construction.In some of these remote communi-
ties,the population could more than quadruple.The installation of a con-
struction camp would not mitigate the impacts on the social and economic
structure of a community.
The expenditures that flow out of the region account for investment in
equipment and supervisory personnel.For this large-scale project,a larger
proportion of the expenditures can be attributed to the civil costs.Approxi-
mately 35 percent of an investment in the project will be made outside the
Railbelt Region,while 65 percent will be made within the Railbelt.The break-
down of operating and maintenance expenditures for a hydroelectric project
will be approximately 11 percent spent outside the Railbelt and 89 percent
spent within the region.
5.5
-'~'.m;,,;trtt·7nIP··"··"'··inr·I ~
6.0 INSTITUTIONAL CONSIDERATIONS
This section presents an inventory of major federal,state of Alaska,and
local environmental regulatory requirements that would be associated with the
development of a 480-MW hydroelectric power plant at Chakachamna Lake.The
inventory is divided into three subsections,setting forth federal,state,and
local environmental requirements.
6.1 FEDERAL REQUIREMENTS
The Chakachamna hydro project may be exempt from the National Pollutant
Discharge Elimination System (NPDES)permitting program that is operated for
Alaska by the EPA pursuant to Section 402 of the Clean Water Act.The NPDES
permit is required for discharges from a "po int source.1I As this term is
defined (40 CFR 122.3)it is unclear whether this project would include a
point source discharge into navigable waters,as EPA generally does not issue
NPDES permits to hydroelectric projects if water merely passes through a
turbine from the reservoir to the receiving waters.However,an NPDES permit
will likely be required if during construction of a dam,water i~discharged
from settling basins,or if floor drains,sanitary systems,etc.are dis-
charged during operation.This issue can only be resolved with the devel-
opment of additional information regarding project design.
The most important permit appl i cab 1e to a hydroe lectri c project that
could have a substantial impact upon the licensing schedule is the license
that must be obtained for construction of a water power project of more than
2000 horsepower installed-capacity.These licenses are issued by the Federal
Energy Regulatory Commission (FERC)as required by the Federal Power Act
(16 USC 792-828c).FERC issues these licenses according to the regulation~in
18 CFR 4.
An application for a FERC license for a new project is quite complicated,
requiring the preparation of seven exhibits (18 CFR 4.41).(These regulations
are presently under review.The format may be changed significantly.)Among
these is a requirement that the applicant show evidence of compliance with
requirements of state laws with respect to water appropriation and use of
6.1
01
[--E d
water for power production (18 CFR 4.41 Exhibit D).This is accomplished by
showing that state .permits have been obtained t and that the state has certi-
fied that water quality will be maintained as is required by section 301 of
the Clean Water Act.As a result t submission of a complete FERC permit cannot
occur prior to receipt of the prerequisite permits and certifications.Fur-
thermore t the FERC review process for application approval is lengthy even
after a prospective permittee has exerted considerable time and energy in
submitting all requisite documentation.
Licensing of.a hydroelectric project in Alaska could be completed,barring
any major difficulties in obtaining a FERC permit,in 42 months.The critical
element in the schedule will be the FERC permit t which FERC cannot approve
before the applicant has submitted its environmental report (18 CFR 4.41
Exhibit)and state water use permits.This schedule assumes that all neces-
sary environmental monitoring can be completed in 12 months.As climatic
conditions in Alaska could impede the collection of necessary field data,the
licensing schedule could be delayed.Note also that NEPA compliance t includ-
ing EIS preparation,for a hydroelectric project is generally the responsi-
bility of FERC.In the scoping sessions between federal agencies and the
applicant,FERC is generally selected as the lead agency for a hydro power
project.These and other federal requirements are summarized in Table 6.1.
6.2 STATE REQUIREMENTS
In addition to the FERC permit t a hydroelectric project will be subject
to some specialized permits required in Alaska,such as the dam permit and
water use permit issued by the Alaska Department of Natural Resources and the
permit to interfer·e with salmon spawning streams and waters issued by the
Alaska Department of Environmental Conservation.The state of Alaska also
imposes special requirements upon some projects if the project site is located
on lands that have been reserved by the state requirements restricting use of
land (due to preservation of the land by state government or native Alaskans)
under one of several special programs.The state requirements are summarized
i n Tab 1e 6.2.
6.2
TABLE 6.1.Federal Regulatory Requirements
A~
Environmental
Protection Agency
US Army Corps of
Engineers
Federal Energy
Regulatory
Commi ss i on
National Marine
Fisheries Servicel
Fish and Wildlife
Service
-..
Requirement
National Pollutant
Discharge Elimination
System
Construction Activity
in Navigable Water
Discharge of Dredged
or Fill Material
Environmental Impact
Statement
License for Major New
Hydropower Project
Threatened or
Endangered Species
Review
Statute
Scope or Authority
Discharges to 38 USC 1251
Water et ~.;
sectlon 1342
Construction in 33 USC 401
Water et seq.;
section 403
Discharges to 33 USC 1251
Water et seq.;
section 1342
All Impacts 42 USC 4332
section 102
Construction of 16 USC 792
Hydropower et seq.
Project
Air,Water,16 USC 1531
Land et seq.
~
:~
I".)
,~
Advisory Council
on Historic
Preservation
All Federal
Agencies
Determination that
Site is not
Archeologically
Significant
Determination that
Site Does Not Infringe
on Federal Landmarks
Executive Order
No.11990
Executive Order
No.11988
6.3
Land Use
Land Use
Development
in Wetlands
Development
in Floodplains
16 USC 402 aa
et seq.
16 USC 416
et seq.
TABLE 6.2.State Regulatory Requirements
Agency
Alaska Department
of Environmental
Conserv at ion
Alaska Department
of Natural
Resources
Alaska Office of
the Governor
Alaska Department
of Fish and Game
Requ irement
State Certificate that
Discharges Comply with
CWA and State Water
Quality Requirements
Solid Waste
Disposal Permit
Permit to Interfere
With Salmon Spawning
Streams and Waters
Water Use Permit
Rights-of-Way Easement
Dam Permit
Coastal Use Permit
Anadromous Fish
Protection Permit
Critical Habitat
Permit
Fishways for
Obstruction to
Fish Passage
6.4
Scope
Discharges to
Water
Solid Waste
Construction in
Water
Appropriation
of Water
Right of Way
on State Lands
Construction of
Dam 10 Feet
High or More
Land Use
Fish Protection
Fish and Game
Protection
Fish Protection
Statute
or Authority
33 USC 1257
et seq.;
section 1341
Alaska
Statute
46.03.100
Alaska
Statute
Alaska
Statute
46.15.030-185
11 Alaska
Admi ni str at ive
Code 58.200
Alaska
Statute
Alaska
Statute
46.40
Alaska
Statute
16.05.870
Alaska
Statute
16.20.220
and .260
Alaska
Statute
""
6.3 LOCAL REQUIREMENTS
The Chakachamna hydroelectric project will be l~cated in the Kenai
Peninsula Borough on Cook Inlet,and will be subject to the permitting and
zoning restrictions imposed by the borough.In addition,the Kenai Peninsula
Borough has a solid waste disposal program to which the project may be
subject.Borough regulations require that the plans for any construction in
the borough must be approved by borough authorities before construction can
begin.
6.5
bWllrntrrnrnrrim·TTnnn·II >7";1::!:TCnrtr t w nct!vlir ,J
7.0 ONGOING PROJECT STUDIES
',,/'
Bechtel Civil and Minerals,Inc.is currently performing under contract
to the Alaska Power Authority a detailed feasibility analysis of the Chaka-
chamna hydroelectric project (Bechtel 1981).This work commenced in the fall
of 1981 and is scheduled for completion late in 1982.Bechtel submitted a
letter report to the Power Authority dated November 23,1981,which-described
studies of alternative development schemes for the project.
Four alternative project layouts were identified in Bechtel·s report,
with estimates of power output and construction costs provided for each.Two
alternatives,identified as Alternatives A and B,involve diverting the basin
flow from Lake Chakachamna via a pressure tunnel to a powerhouse on the
McArthur River.Alternative A would divert all of the inflow to the power-
house,while Alternative B would provide a downstream fish release to the
Chakachatna River,thus reducing the amount of flow available to the power
plant.Alternatives C and D involve developing the head along the Chakachatna
River itself,by means of a pressure tunnel and powerhouse.Alternative C
would provide a nominal downstream fish release,while Alternative 0 would
provide no fish release.None of the four alternatives include a dam in the
proposed layout and all would utilize a lake tap-type intake structure.A
tabulation of the cost estimate and power output potential from each alterna-
tive as presented in Bechtel·s report is shown in Table 7.1.
Subsequent to receipt of Bechtel's report,Ebasco was verbally advised by
Bechtel that as a result of discussions with the Power Authority,a decision
was made to adopt Alternative B for further study.Ebasco was also advised
that the cost estimate presented in the report had been revised to reflect an
allowance of S50 million for fish passage facilities.The total project cost
has been revised to $1.45 billion,with the total cost of energy estimated to
be 43.6 mills/kWh.
Of the four alternatives identified in Bechtel's report,Alternative A
most closely resembles the scheme shown by Ebasco in this report.Both schemes
involve diversion of all Chakachamna Lake inflow to the McArthur River,with
7.1
TABLE 7.1.Project Development Alternatives Identified by Bechtel(a)
Item
Installed Capacity (MW)
Firm Annual Generation (GWh)
Capital Costs (S billions)(b)
Annual Costs (S millions){C)
Net Cost of Energy
(mills/kWh)
Allowance for 0 and M
(mill s/kWh)
Total Cost of Energy
(mills/kWh)
Development Alternative/Powerhouse Location
ABC 0
McArthur McArthur Chakachatna Chakachatna
River River River River
400 330 300 300
1665.5 1374.1 1249.2 1249.2
1.5 1.4 1.6 1.6
59.9 55.9 63.9 63.9
35.9 40.7 51.1 51.1
1.5 1.5 1.5 1.5
37.4 42.2 52.6 52.6
(a)From letter report on Chakachamna Hydroelectric Project Development
Studies by Bechtel Civil and Minerals,Inc.,November 23,1981,Alaska
Power Authority.
(b)January 1982 price level,includes interest during construction at
3 percent per annum.
(c)Equal to 3.99 percent of capital cost,includes interest,amortization and
insurance for 50 year project life.
no fish release allowance.While a detailed comparison of the project lay-
outs,cost estimates and power output prepared by Bechtel and Ebasco is beyond
the scope and purpose of this report,certain general observations are dis-
cussed below.
The two project layouts are generally similar.Both include a lake tap,
gate shaft,pressure tunnel,surge tank,penstock,a four-unit powerhouse,a
switchyar~,access roads,and a transmission line.The only significant dif-
ferences between the two schemes are:a)Bechtel's Alternative A proposes an
underground pOrJerhouse with a tailrace surge chamber and tailrace tunnel,while
-Ebasco layout includes a surface-type powerhouse with a tailrace channel,and
7.2
liP·2L .lSlILliLii3U.~.~
b)Ebasco's layout includes a spillway tunnel at the lake outlet,while
Bechtel's layout does not.Our assumption of a surface-type pow,erhouse is
based on available mapping and a brief site visit to the general vicinity of
the powerhouse.Wi th thi s information,we see no apparent reason that a sur-
face powerhouse could not be constructed,and we have included this type of
powerhouse in our conceptual layout because it is generally more economical
than construction of an underground powerhouse,as the Bechtel report also
acknowledges.Inclusion of a spillway tunnel at the lake outlet was consid-
ered prudent in view of the uncertainty of the action of Barrier Glacier
during the life of the project and the influence of the glacier on passage of
flood flows through the natural outlet of the lake.
Certain differences are also present between Bechtel's Alternative A and
the Ebasco layout in the estimates of installed capacity,power output,and
operational characteristics.Bechtel's scheme indicates an installed capacity
of 400 MW and an estimated annual firm energy production of 1753 GWh (before
transmission and station service losses).Ebasco has selected an installed
capacity of 480 MW (the same as that shown in the Acres American,Inc.(1981)
Development Selection Report)and has estimated the average annual energy to
be 1982 GWh (before transmission and station service losses).While a detailed
investigation of the reasons for these differences was not undertaken,certain
reasons can be readily identified.
The reservoir inflows utilized in Bechtel's power studies have been devel-
oped by adjusting the recorded discharges at the outlet of the lake to reflect
the effect of the storage in the lake.The scope of the Ebasco study being
much more limited,such extensive in-house data adjustment has not been
included and the lake outflows readily available as gaging station records
have been taken to also directly represent the basin inflows.This less
sophisticated approach will have the effect of slightly overstating the actual
available inflow during dry years and understating the inflow during wet
years.The long-term average available inflow should,however,be essentially
the same for the two methods.The average annual inflow for the period of
record used by Bechtel (calendar year 1960 through 1970)was 3,547 cfs,while
the average inflow used by Ebasco was 3,651 cfs for the hydrological period of
7.3
-"
water year 1961 through 1972.The average discharge for the entire period for
the USGS gage at the lake outlet was 3,646 cfs.
The active storage utilized in Bechtel1s proposed scheme lies between ele-
vations 1128 and 1028,which corresponds to 1,526,000 acre-feet.The active
storage used in the operation proposed by Ebasco is 2,080,000 acre-feet,
between elevations 1127 and 968.The greater amount of active storage should
make little difference in the estimates of average annual energy,but it will
have the benefit of providing a larger proportion of firm energy,everything
else being equal.
Minor differences also exist between the two schemes in tunnel diameter
and assumed tailwater elevation.Considering the scope of this study and the
early stage of Bechtel's study as represented in their letter report of
November 23,1981,the differences between the layouts and power output esti-
mates of the two schemes are not substantial.
7.4
•, ;rmS'••
8.0 REFERENCES
-
Acres American Incorporated.1981.
Selection Report -Subtask 6.05.
Susitna Hydroelectric Project Development
Alaska Power Authority,Anchorage,Alaska.
Bechtel Civil and Minerals.1981.Chakachamna Hydroelectric Project Interim
Report.Prepared for Alaska Power Authority,Anchorage,Alaska.
U.S.Bureau of Reclamation (USBR).1962.Chakachamna Project Status Report.
U.S.Department of the Interior,Washington,D.C.
8.1