HomeMy WebLinkAboutBrowne Hydroelectric Alternative for the Railbelt Region of Alaska 1982RAI
018
VOL.1S
I U;\ s;:; i # :
Alaska Energy Authority
LIBRARY COPY
Browne Hydroelectric
Alternative for the Railbelt
Region of Alaska
Volume xv
Ebasco Services Incorporated
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
~~B U II ~". a e e
Pacific Northwest Laboratories
Browne Hydroelectric Alternative
for the Railbelt Region of Alaska
Volume XV
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
Richland, Washington 99352
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ACKNOWLEDGMENTS
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
Engineering 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
prepared by Battelle, Pacific Northwest Laboratories of Richland, Washington.
iii
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 (-15 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. Environ-
mentally, 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. High capital
investment costs render many sites noncompetitive with alternative sources of
power.
Based on environmental and economic considerations, the Browne hydro-
electric project was among severai hydroelectric projects identified as
preferred hydroelectric alternatives to the Upper Susitna project. An
individual study of the Browne project was commissioned, partly because of its
estimated capacity and energy production, which were somewhat greater than
most of the other sites, and also because of its apparently modest environ-
mental impact. This report, Volume XV of a series of seventeen reports,
documents the findings of this study.
v
Other power-generating alternatives selected for in-depth study included
pulverized coal steam-electric power plants, natural gas-fired combined-cycle
power plants, the Chakachamna hydroelectric project, large wind energy con-
version 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 Re 1ion of Alaska. Prepared by Ebasco
Services Incorporated and Battel e, 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, Alaska.
Ebasco Services, Inc. 1982. Chakachamna 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, Paclflc 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.
vi
SUMr~RY
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 to construct due to high capital costs, or appear to
have the potential for unacceptably severe environmental impacts. Among the
sites of sufficient size to be of interest in the context of a Railbelt-wide
electric power planning and that present potentially competitive economic
characteristics and acceptable environmental impacts is a site on the Nenana
River, approximately 2 miles north of the Alaska Railroad siaing of Browne.
The proposed Browne hydroelectric project would be a conventional hydro-
electric development, consisting of a dam, reservoir and power plant. The
installed capacity of the power plant would be 100 MW. Power from the project
would be transmitted to the proposed Anchorage-Fairbanks intertie, approxi-
mately 3-1/2 miles north of the powerhouse. The estimated annual average
energy production would be 430 GWh and the estimated annual firm energy
production would be 298 GWh.
Cost estimates for the proposed project indicate an overnight capital
cost of 4460 $/kW, with operation and maintenance costs of 4.80 $/kW/yr.
Based on a 1990 in-service date, levelized busbar energy costs were estimated
to be 52 mills/kWh in January 1982 dollars. (Not included in this estimate is
the cost to relocate approximately 8 miles of highway and 16 miles of
railroad.)
Approximately 9 years would be required for project construction, includ-
ing preconstruction studies and a 4-1/2 year construction period. Given a
mid-1982 authorization to proceed, the project could be in service in late
1990.
Environmental effects of the Browne project appear to be relatively
minor. Anadromous fish runs are not known to be present in this portion of
the Nenana River and no critical terrestrial habitat appears to be present in
the area of the reservoir.
vii
Two engineering constraints may impact the feasibility of the project.
P~vious materials underlie the proposed site and the dam would be located
within the proximity of a seismically active zone. Pervious materials can be
removed by dredging. However, their depth and extent are not known at this
time. Structures can be designed to withstand severe seismic loads, but at
additional cost. An uncertainty relating to the required seismic design
considerations is the presence and extent of soils or sands subject to
liquefaction during a seismic event.
vii i
CONTENTS
ACKNOWLE DGMENTS
PREFACE
SUMMARY
1.0 I NTRODUC TI ON
2.0 PROJECT DESCRIPTION •
2.1 SITE DESCRIPTION
2.2 PLANT DESCRIPTION
2.2.1 Overview
2.2.2 Dam and Reservoir •
2.2.3 Power Plant .
2.3 TRANSMISSION SYSTEM •
2.4 SITE SERV ICES .
2.5 CONSTRUCT! ON
2.5.1 General Construction
2.5.2 Construction Schedule
Methods
.
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 Plant Life
2.6.4 Operating Work Force and General
Requirements .
3.0 COST ESTIMATES •
3.1 CAPITAL COSTS •
ix
Maintenance
iii
v
vi i
1.1
2.1
2.1
2.5
2.5
2.18
2.19
2.20
2.21
2.22
2.22
2.23
2.29
2.29
2.29
2.30
2.32
2.32
3.1
3.1
3.1.1 Construction Costs
3.1.2 Payout Schedule
3.1.3 Escalation
3.2 OPERATION AND MAINTENANCE COSTS
3.2.1 Operation and Maintenance Costs .
3.2.2 Escalation
3.3 COST OF ENERGY .
4.0 ENV IRONMENTAL AND ENGINEERI NG SITI NG CONSTRAINTS
4.1 ENVIRONMENTAL SITING CONSTRAINTS
4.1.1 Water Resources
4.1.2 Air Resources
4.1.3 Aquatic and Marine Ecology .
4.1.4 Terrestrial Ecology
4.1.5 Socioeconomic Contraints
4.2 ENGINEERING SITING CONSTRAINTS
5.0 ENVIRONIVIENTAL AND SOCIOECONOMIC CONSIDERATIONS
5.1 SUMMARY OF FIRST ORDER ENVIRONMENTAL IMPACTS.
5.2 ENVIRONMENTAL AND SOCIOECONOMIC EFFECTS.
5.2.1 Water Resource Effects.
5.2.2 Air Resource Effects
5.2.3 Aquatic and Marine Ecosystem Effects .
5.2.4 Terrestrial Ecosystem Effects
5.2.5 Socioeconomic Effects
6.0 INSTITUTIONAL CONSIDERATIONS
6.1 FEDERAL REQUIREMENTS
x
3.1
3.1
3.1
3.4
3.4
3.4
3.4
4.1
4.1
4.1
4.2
4.2
4.2
4.2
4.3
5.1
5.1
5.1
5.1
5.1
5.2
5.3
5.3
6.1
6.1
6.2 STATE REQUIREMENTS
6.3 LOCAL REQUIREMENTS .
7.0 REFERENCES
xi
6.2
6.5
7.1
FIGURES
2.1 Area Site Plan.
2.2 General Project Arrangement
2.3 Powerhouse Plan
2.4 Powerhouse Section
2.5 Power Intake Elevation and Typical Section
2.6 Power Intake and Tunnel
2.7 Construction Schedule
2.8 Construction Work Force Requirements
3.1 Cost of Energy Versus Capacity Factor
3.2 Cost of Energy Versus First Year of Commercial
Operation •
xii
2.3
2.7
2.9
2.11
2.13
2.15
2.25
2.29
3.5
3.6
TABLES
2.1 USGS Gaging Stations on the Nenana River
2.2 Average Monthly Discharge in Nenana River Near
Healy, Alaska
2.3 Summary of Project Features
2.4 Reservoir Operation During Average Year.
3.1 Bid Line Item Costs for the Browne Hydroelectric
Project
3.2 Payout Schedule for the Browne Hydroelectric
Project
5.1 Primary Environmental Effects.
6.1 Federal Regulatory Requirements
6.2 State Regulatory Requirements.
xiii
2.5
2.6
2.17
2.31
3.2
3.3
5.2
6.3
6.4
1.0 INTRODUCTION
The proposed Browne hydroelectric project will be a conventional hydro-
electric development consisting of a dam, reservoir, and power plant located
on the Nenana River approximately 65 air miles southwest of Fairbanks. The
Alaska Railroad is adjacent to the powerhouse site and the Anchorage-Fairbanks
highway is located about 1 mile west of the Nenana River. A dam will be built
across the Nenana River to form the storage reservoir. Water will be conveyed
from this reservoir through a high-pressure tunnel and penstocks to a power
plant with an installed capacity of 100 MW. The power from the project will
be brought into the proposed Anchorage-Fairbanks intertie.
The advantages of the project may be categorized generically, as related
to hydro power, and on a site-specific level. In a generic sense, the perti-
nent advantages of hydro power are: zero fuel costs, maturity of technology,
simplicity, reliability, and quick responsiveness of the generating equipment
to changes in load.
More specific advantages of the Browne site are its close proximity to
existing transportation facilities, thus minimizing access requirements.
Also, transmission corridor requirements will be minimal due to the suggested
routing of the Anchorage-Fairbanks intertie, which is within 3 miles of the
Browne powerhouse location (Commonwealth Associates 1981). Geographically,
the site is centrally located and well removed from any natural physical
impediments (e.g., mountainous terrain, glaciers, large rivers, etc.). Poten-
tial environmental effects appear to be minor. Finally, the conceptual layout
developed herein is quite conventional, containing no unusual project features
and therefore should not require any unusual construction techniques.
The project site, however, possesses certain disadvantages. Seismically,
the site is located in an area of major activity, with the powerhouse beiDg
approximately 25 miles north of a significant fault zone. Foundation mate-
rials along this portion of the Nenana River are not generally well suited for
a dam foundation. This is particularly true for that portion of the founda-
tion that lies directly under the dam axis. These materials basically consist
of coarse pervious sands and gravels.
1.1
Another significant disadvantage of the Browne project is that its devel-
opment will require the relocation of the Alaskan Railroad siding at Browne,
as well as the relocation of approximately 16 miles of Alaska Railroad track
and 8 miles of the Anchorage-Fairbanks highway. At their present locations,
these features will be inundated by the reservoir.
1.2
2.0 PROJECT DESCRIPTION
2.1 SITE DESCRIPTION
The project site will be located at the start of the foothills north of
the Alaska Mountain Range. Topography in the vicinity of the proposed reser-
voir, along the Nenana River, is relatively flat. This topography rises
fairly abruptly to the east of the river valley and more gradually to the west
(see Figure 2.1). The dam for the project will be constructed across this
valley at its narrowest point.
Seismically, the area is very active. In 1937 and again in 1947 severe
earthquakes shook the area. The epicenter of the 1947 earthquake was at
Clear, 10 miles north of the proposed powerhouse, and registered an intensity
of VIII+ on the Mercalli Scale. The 1937 earthquake, slightly less intense
than the 1947 event, had its epicenter near Salcha, approximately 50 miles
east of the powerhouse. Also, approximately 25 miles south of the proposed
powerhouse is a major fault zone that has produced offsets within Holocene
sediments dated younger than 10,000 years.
The Nenana River originates on the northern slope of the Alaska Range and
runs generally in a northerly direction to the Tanana River. The Browne
damsite is located approximately 1.7 miles downstream from the railroad siding
at Browne, with a drainage area of approximately 2,450 square miles above the
damsite. Streamflow records exist for three locations on the river, as shown
on Table 2.1.
In hydropower simulation studies performed by Acres American, Inc. (1981),
the 23-year period of record for the USGS gage near Windy WaS used to generate
a monthly streamflow model for the Browne site. This was accomplished by
multiplying the records from the gage near Windy times the ratio of the drain-
age area at the damsite to the drainage area of the gage (2,450/710 = 3.45).
In generating a monthly streamflow model for use in Ebasco1s independent
simulation studies, the 29-year period of record for the gage near Healy was
utilized rather than the gage near Windy. The Healy gage was considered more
appropriate for use than the gage near Windy because the drainage area at
2.1
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FIGURE 2.1. Area Site Plan
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TABLE 2.l. USGS Gaging Stations on the Nenana River
Drainage
Gage No. Gaging Station A re a (m i 2 ) ( a) Period of Record
15516000 Nenana River 710 10/51-9/73
Near Windy
15518000 Nenana River 1910 10/50-9/79
Near Healy
15518300 Nenana River 2450 10/64-9/68
Near Rex
(a) Drainage area at Browne damsite is approximately 2,450 mi 2 •
the Healy gage (1,910 mi 2 ) is closer in size to that at the damsite (2,450
mi 2 ) and the period of record is longer. The average monthly flows for the
29-year period of record as recorded at the Healy gage are shown in Table 2.2.
The flows at the damsite were estimated by multiplying the flows at the Healy
gage times the ratio of the drainage area at the damsite to the drainage area
at the gage (2,450/1,910 = 1.28). The estimated average annual flow at the
damsite is 4,500 cfs.
2.2 PLANT DESCRIPTION
2.2.1 Overview
The Browne project will consist of a dam, spillway, storage reservoir,
powerhouse, and appurtent structures. The storage reservoir will be formed by
an earth and rockfill dam. The intake, water conductors, and powerhouse will
be located in the left abutment and the spillway will be located in the right
abutment. A site plan of the project is shown in plan and section in Fig-
ure 2.1 and the general arrangement of project features is shown in Figure 2.2.
Detailed plans and sections of the proposed powerhouse are shown in Figures 2.3
and 2.4, and details of the power intake and tunnel are shown in Figures 2.5
and 2.6. A summary of the principal project features is shown in Table 2.3.
2.5
TABLE 2.2. Average Monthly Di scharge in Nenana River Near Healy, Alaska (cfs)(a,b)
Water
Year Oct. Nov. Dec. Jan. Feb. Mar. Apr. ~ June ~ ~ Sept.
1951 1,354 610 565 545 465 430 627 5,874 7,211 8,155 7,032 8,461
1952 1,929 1,092 830 600 500 480 510 2,348 10,050 11 ,290 7" 355 4,701
1953 3,074 1,300 800 430 360 430 600 3,640 10,990 9,082 8,460 5,978
1954 1,702 750 650 570 488 390 450 3,130 7,618 7,386 9,580 5,260
1955 2,429 1,200 552 500 460 440 380 2,97<) 9,906 10,760 9,154 6,290
1956 1,858 825 640 550 510 440 437 4,222 11,240 10,010 9,80S 6,003
1957 2,213 875 715 689 608 514 510 5,451 12,370 7,573 6,4:'0 6,185
1958 2,474 1,765 1,387 771 457 369 550 3,133 10,260 7,805 8,212 ",132
1959 1,503 745 549 568 481 339 400 4,472 8,963 11,280 7,420 4,475
1960 2,535 1,250 760 688 561 516 580 6,442 5,480 8,069 7,737 6,107
1961 1,995 795 764 730 454 422 635 5,281 9,638 9,034 10,530 4,386
1962 2,208 1,200 760 610 470 420 520 4,443 15,060 10,860 8,035 6,926
1963 2,370 1,160 670 540 500 470 520 5,558 9,883 13,970 12,680 5,450
1964 2,818 1,225 580 580 420 360 505 919 12,,,80 10,260 6,573 3,609
N 1965 2,713 1,200 740 520 440 430 595 4,129 10,630 11 ,080 6,369 7,168 .
en 1966 2,944 1,200 697 500 500 500 540 2,450 12,440 7,589 7,913 4,963
1967 2,375 740 624 555 491 460 450 3,899 11,910 15,340 13,090 4,816
1968 1,829 900 713 660 625 599 632 4,749 14,180 10,310 6,064 2,941
1969 1,287 404 262 228 220 220 468 4,132 7,434 !:i,876 4,307 2,109
1970 1,034 659 530 477 452 440 507 3,953 7,882 11,110 7,284 4,3Ui
1971 1,880 756 546 540 540 540 533 3,716 14,500 10,730 10,410 4,865
1972 2,384 1,293 877 678 539 462 434 3,361 10,330 8,9n 6,638 3,999
1973 2,532 1,667 794 600 500 450 524 3,287 6,201 7,709 7,178 3,136
1974 1,416 767 415 247 190 190 202 2,536 5,721 7,339 6,434 4,907
1975 2,366 913 955 500 500 500 533 2,864 10,390 9,877 6,630 5,410
1976 2,045 800 627 474 400 3bO 448 3,316 7,216 5,871 !:i,436 i,747
1977 1,694 967 700 600 500 450 483 3,278 12,030 10,010 8,129 5,b21
1978 3,511 1,613 844 651 576 510 806 4,350 6,336 8,418 6,796 3,678
1979 1,853 927 705 579 500 450 535 4,749 7,494 10 ,180 6,603 4,165
( a) From USGS Gage No. 15518000, Nenana River near Healy (Drainage Area = 1,910 mi 2 ).
( b) Flows at damsite computed by multiplying recorded flows by ratio of drainage areas
(2,450/1,910 = 1.28).
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2.13
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SECTIONAL PLAN SECTIONAL PLAtI AT g TUNNEL 2.15
FIGURE 2.6. Power Intake and Tunnel
TABLE 2.3. Summary of Project Features
Intake Structure
Outside dimensions: width -39 ft
length -60 ft
height 145 ft
Two intake gates
Power Tunnel: 700 lineal feet
23 ft inside diameter
concrete 1 i ned
Penstocks: 1 -400 lineal feet
16 ft inside diameter
steel-l tned
4 -100 lineal feet
8 ft inside diamter
steel-lined
Powerhouse: 100 MW installed capacity
4 Francis Turbines, 34,600 hp, 170 ft net design head
4 Generators, 27,800 kVA, 225 rpm at 0.90 PF
Outside Powerhouse rlimensions: width: 75 ft
length 244 ft
height 75 ft (35 ft above grade)
Transformers (2): 3-phase 240 MVA, 13 kV to 138 kV
Tailrace Channel: width = 90 ft
depth = 23 ft
length = 500 ft
Dam: Earth and rockfill, zoned embankment
length = 3,000 ft
maximum height = 200 ft
crest width = 25 ft
upstream slope 2.5:1
downstream slope 2.0:1
Damsite Excavation: 2 ft under entire dam plus 30 feet beneath
the impervious core in the streambed tapering
off to 10 feet at the top of the dam
(these values are assumed no data was
available for deptn of gravels at damsite)
River Diversion (2): 12 ft diameter
concrete encased diversion conduits -600 ft long
Spillway: 190 ft wide tapering to 150 ft wide
40 ft deep at the crest
850 ft long
4 tainter gates (40 ft x 40 ft)
Spillway Discharge Channel: 1000 ft long, approximately 250 ft wide
and 10 ft deep
Switchyard Dimensions: 300 ft x 100 ft
Access Roads: 3.5 miles
Transmission Line: 3.5 miles 138 kV
(all new corridor)
Relocations: Alaska Railroad siding at Browne
16 miles of Alaska Railroad track
8 miles of Anchorage-Fairbanks Highway
2.17
The maximum gross head at the project will be 195 feet and the average
net operating head is estimated to be approximately 170 feet. Maximum
reservoir storage will be 1,100,000 acre-feet at the normal maximum pool
elevation of 975. Dead storage will be 340,000 acre-feet, which provides a
total usable storage of 760,000 acre-feet. It is estimated that approximately
88 percent of the total flow available from the drainage basin will be used
for power proauction. The installed capacity of the plant will De 100 MW and
the average annual energy production from the facility is estimated to be
430 GWh with a 49 percent plant factor.
Access to the site will be by road ana will utilize existing transporta-
tion facilities as much as possible. Suggested plant access routes to be
constructed are shown in Figure 2.1.
Power transmission from the site will tie into the projected Anchorage-
Fairbanks grid system and will be along the corridor shown in Figure 2.1.
2.2.2 Dam and Reservoir
The dam will be constructed of zoned earth and rockfill. It will be
approximately 200 feet high (crest elevation 995 ft) over most of its 3000-
foot length and will have 2-1/2 to 1 upstream and 2 to 1 downstream side
slopes. The central portion of the dam, approximately 15 percent of the
width, will consist of an impervious clay core and the outer portions will
consist of rockfill. Sand and gravel filters will separate the central core
from the rockfi1l.
The concrete-lined spillway will be cut deeply into the left abutment.
It will be 190 feet wide, 40 feet deep, 800 feet long and"will be equipped
with four 40 ft by 40 ft tainter gates. The crest of the spillway will be at
elevation 955 feet. The spillway discharge channel will be cut in the river
sands and gravels and will be approximately 1000 feet long, 250 feet wide, and
10 feet deep.
As discussed previously, the maximum reservoir pool will be at elevation
975 feet, with a maximum reservoir storage of 1,100,000 acre-feet. At this
level, the reservoir will extend south "of the dam for approximately 11 miles.
The formation of the reservoir will require the relocation of approximately
2.18
16 miles of Alaska Railroad track and 8 miles of the Anchorage-Fairbanks
highway. The reservoir will also inundate a railroad siding referred to as
Browne, which is shown on the USGS Fairbanks A-5 quadrangle as five structures
adjacent to the Alaska Railroad about 2 miles south of the damsite. Discus-
sions with personnel from the Alaska Railroad indicate that the Brown siding
is uninhabited.
2.2.3 Power Plant
The powerhouse will be an indoor-type, above-ground powerhouse located on
the east bank of the Nenana River. The structure will be reinforced concrete,
with the approximate dimensions being 244 feet long, 75 feet wide, and 75 feet
high, with 35 feet above grade.
The general layout of the powerhouse is shown in Figure 2.3. The power-
house will contain four vertical water wheel generating units rated at
27,800 kVA, with a 0.90 power factor. The generators will be driven by four
Francis-type turbines at a synchronous speed of 225 rpm.
The powerhouse will consist of five monoliths, with the end bay being
designated as the erection bay. The erection bay monolith will be in line
with the axis of the powerhouse and its ground floor will be approximately at
the same level as the turbine floor.
The steel superstructure will house the generator floor, public facilities
and access, office, control, and equipment areas. The principal elements of
the concrete substructure will be the turbines and waterways, but it will also
house service functions, including the dewatering sump and pumps, oil storage
and purification, potable water and sewage systems.
The generator floor will have the actuator cabinet, potential transformers
and surge cubicles, switchgear, battery room, and cable vault. The control
room will be located at the same level as the generator floor. Adjacent to
the control room will be the heating and ventilation (H and V) equipment
room. Additional powerhouse H and V equipment rooms will be located at this
level at the rear of the powerhouse.
2.19
The turbine floor will support the actuator cabinet, pressure tank,
excitation control and rheostat cubicles. The dewatering pumps and motors
will be locatea on a platform in the sump pit, just under the turbine floor.
A butterfly valve will be located immediately upstream of each turbine.
Hatches with removable covers will be located in the upstream service parking
area for installation and maintenance of the valves.
To supply water to the powerhouse, a concrete intake structure will be
constructed in the upstream right abutment. Details of this structure are
shown in Figure 2.2. A power tunnel will be excavated through the right
abutment connecting the intake structure to the powerhouse (see profile in
Figure 2.1). This tunnel will have a 23-foot inside diameter and an invert
elevation of 850 feet at the intake. The 600-foot-long upstream half of this
tunnel will be reinforced concrete lined and slope to elevation 780 feet where
it will then connect to a 16-foot-diameter steel-lined penstock tunnel. This
subhorizontal tunnel reach will continue to the vicinity of the powerhouse
where it will, through double bifurcations, reduce to four 8-foot-diameter
steel-lined penstock tunnels connecting to the turbines.
A tailrace channel with an average width of 90 feet will be excavated to
the natural river channel from the downstream end of the powerhouse draft
tubes. The average tailwater elevation will be 780 feet.
A two-bay, one-and-a-half breaker switchyard containing six breakers and
measuring approximately 300 x 100 feet will be located adjacent to the power-
house. Two main 240 MVA three-phase transformers will transform the voltage
from 13 kV to 138 kV transmission voltage.
2.3 TRANSMISSION SYSTEM
Transmission of power from the site will be over a 138-kV line and will
utilize the Fairbanks-Anchorage intertie as suggested in the Commonwealth
Associates (1981) report. The proposed location of the interconnection of the
transmission line from the Browne project with the Fairbanks-Anchorage inter-
tie is shown in Figure 2.1.
2.20
Basically, an overhead line will start in the switchyard close to the
powerhouse and head northward along the flood plain of the Nenana River for
approximately 3.5 miles. At that point connection with the Fairbanks-
Anchorage intertie will be provided. The exact location of this intertie has
not yet been finalized, however. The suggested 3.5-mile transmission corridor
is so short and direct that no alternative routing is considered necessary.
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, 50 to 80 feet high and pin-connected
to their foundations. Steel H-pile foundations will be required, with suffi-
cient penetration to withstand the active freeze-thaw zone as well as the
normal. structural uplift forces. This overall structure will combine the
necessary strength with an inconspicuous appearance ana will be economical to
construct.
2.4 SITE SERVICES
Access to the site will be provided by road to both abutments. The left
abutment/spillway will be reached by the relocated Anchorage-Fairbanks highway
and via a 1/2-mile access road. The right abutment will be provided access
via a 3-mile road paralleling the existing railroad and connecting with the
Anchorage-Fairbanks highway. In addition. the existing railroad will be
utilized for transportation of major equipment items to the powerhouse during
construction. These access routes are shown in Figure 2.1.
The formation of the reservoir will require the relocation of· approxi-
mately 16 miles of Alaska Railroad track to higher ground about 1/2 mile to
the east. Similarly. about 8 miles of Anchorage-Fairbanks highway will require
relocation 1 mile to the west of its present alignment.
No pipeline. air, or waterway access will be required. Living facilities
during construction will be provided by either a trailer park-type arrangement
or by temporary housing. No formal living facilities will be required during
operation because the plant will be remote-controlled.
2.21
2.5 CONSTRUCTION
2.5.1 General Construction Methods
Prior to the start of construction of the dam, its entire foundation and
abutments will be cleared and grubbed. Information on the amount of sands and
gravels that will have to be excavated from beneath the dam impervious core
alignment is not available and considerable quantities may prove to be
involved. In addition, any other unsuitable material, such as excessively
compressible materials, will be stripped from beneath the other dam zones.
For estimating purposes, it was assumed that 2 feet of stripping were required
beneath the entire dam, and 30 feet of excavation beneath the impervious core,
tapering off to 10 feet at the top of the dam.
Concurrently with the above operations, the Nenana River will be diverted.
This will be accomplished in two phases. First, the river will be allowed to
flow along its present course while a double barrel concrete-encased diversion
conduit with a gated intake is constructed to the west of the river. Diver-
sion dikes and temporary cofferdams will be used to contain the river in its
present location. With the completion of the conduit the river will then be
routed from its present course to run through the conduit. This river diver-
sion will remain in effect throughout most of the dam construction. Ulti-
mately, the conduit intake gates will be closed and the conduit filled and
sealed with concrete and grout.
Construction of the dam will utilize standard accepted practices except
for some restrictions. All fill zones, for example, will have to be con-
structed fairly uniformly and simultaneously. No single fill zone w-ill be
allowed to be constructed significantly (more than a few feet) ahead of any
other zone. Also, placement of impervious core materials will not be
permitted during freezing weather and rain.
Excavation of the intake structure, power tunnel, penstock, spillway, and
powerhouse will utilize conventional drilling and blasting methods and will be
performed concurrently with the dam construction. The intake structure and
powerhouse will be conventional in size and location, and should therefore not
require any unusual construction methods or techniques. The only special
2.22
consideration is the harsh winter climate, which could shorten the construc-
tion season by approximately 5 months, particularly during early stages of
construction. To compensate for this, extended work shifts may be utilized in
the summer months.
Construction of transmission lines, as well as access roads and rail-
roads, should not require any unusual construction features or methods except
for those required to cope with permafrost areas wherever encountered. Neither
will the relocation of existing transportation facilities require other special
consideration. However, these relocations will have to be performed without
interruption of the facility's normal operation.
2.5.2 Construction Schedule
A complete project schedule from preliminary field studies though licens-
ing, design, construction, startup testing, and commercial operation is pre-
sented in Figure 2.7. 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 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 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 utilize the water resources of the Nenana River
drainage basin. Power production analysis will consider a range of opera-
tional alternatives; and installed capacities will be investigated to define
an optimum plant size and operation scheme. The selected plant size and
operation scheme will maximize power output benefits and also incorporate any
identified environmental constraints on project operation.
2.23
JULJ -I JAN I --..-
-CALENDAR YEARS I 1 I 2 I 3 I 4 I 5 I 6 I 7 I 8 I 9 I 10
---CALENDAR MONTHS 0 6 12 18 24 30 36 42 4,8 54 6,0 66 72 78 84 90 96 102 108 114 12 o
WORK ACTIVITY
I PRE CONSTRUCTION FIELD
STUDIES
SURVEYING a MAPPING
GEOTECHNICAL' (PRELIMINARY)
ENVIRONMENTAL·
HYDROLOGIC STUDIES I---
CONCEPTUAL ENGINEERING
-Rel/iew of License Application • IT LICENSING -------------------------
ill DESIGN
GEOTECHNICAL ENGINEERING' (FINAL)
DETAILED ENGINE ERING DESIGN ----AND SPECIFICATIONS -
N PROCUREMENT
GENERATING EQUIPMENT ~
0
1Z: CONSTRUCTION !ci
ACCESS ROADS AND RAILROADS -a:::
DAM ClEARING AND EXCAVATION -r--~
RIVER DIVERSION 0 r--
()\M CONSTRUCTION--~ -
SPILLWAY EXCAVATION AND -~
CONSTRUCTION
INTAKE EXCAVATION AND
CONSTRUCTION
TUNNEL/PENSTOCK EXCAVATION AND -~
CONSTRUCTION
POWERHOUSE/TAIlRACE
CONSTRUCTION
SWITCHYARD-
TRANSMISSION LINES
HIGHWAY AND RAILROAD RELOCATION
JlI START UP AND IESTING
FIGURE 2.7. Construction Schedule
2.25
The above 18-month effort will terminate with the preparation and sub-
mittal of the necessary documentation for a license application to the Federal
Energy Regulatory Commission (FERC). For schedule estimating purposes, it is
assumed that 2 years will be required by FERC for processing of the license
application.
Upon submittal of the FERC license application, detailed design will
commence for the dam, 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 avail-
able to support project schedules. Specifically, this work will include the
following:
• Preparation of detailed design criteria and 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,
powerhouse, 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.
• Preparation of technical specifications in sufficient detail to allow
for project procurement and/or construction.
• Establishment of quality assurance requirements based on the detailed
project design, as well as on information provided by vendors and
contractors. These requirements will serve as a basis for construc-
tion and for erection of structures, for procurement, and for instal-
lation, testing, and operation of equipment.
2.27
It is estimated that 2.5 years will be required to carry out these design
efforts.
Procurement activities that will commence after receipt of a FERC license
will consist of the following:
• Preparation of bid documents and evaluation of bids.
• Review of vendor documents and drawings for conformance to architect-
engineer specifications and for confirmation of physical interfaces
with related systems.
• Monitoring and control of procurement contracts.
• Vendor quality assurance services to assure that purchased items are
supplied in accordance with the requirements of applicable
procurement documents.
• Expediting services to assure the timely arrival of purchased items
at the site.
Full-scale construction activities on the main features of the project
will start in the spring after receipt of the FERC license. It is estimated
that construction 0f the entire project could be accomplished in about
4-1/2 years. As shown on the project schedule (Figure 2.7), this estimate is
based on the yearly cessation of outdoor construction activities for a 5-month
period during the winter months. Indoor activities will, however, be per-
formed year-around.
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 approxi-
mately 4 months after construction has been completed.
Slightly less than 9 years would be required for development of the
project, including preconstruction studies, licensing, design, construction
and startup. Given authorization to proceed in mid-1982, the project could be
fully operational by late 1990/early 1991.
2.28
2.5.3 Cons on Work Force ~~~~~~~~~~~
The number of workers necessary for construction of the 100-MW hydro-
electric power plant will vary over the approximate 4-1/2-year construction
period. The distribution of this work force over the schedule duration is
shown in Figure 2.8. Construction is estimated to peak in year 2, requiring a
work force of approximately 515 personnel •
.)(J
5I:v
'" it)
-I'
3>
400
80
'"' "" I..t.J .I>
\J 3eto ~ ~ 80
'" ~ 4fJ
~ ZfI
/II
'0 .,.,
2D
I.d
81
,,0
4q
-:D
.,
II il '*
MONTHS
NO T£: Does 170f Inc/wit!' Yt!'nclol" ptf!rsonl1l!J; ownl!,. Pt!'rJ'ol1l1t1j, A-£ t!'l7gil'lelrS,
or frt:fll'ls.I1'IisJ';Cn bj,4 C'ol'lsfr"lt:'rion pttr.ronn,/ /oC'Pf4"eT t:fIf s/tt!'.
FIGURE 2. Construction Work Force Requirements
2.6 OPERATION AND MAINTENANCE
2.6.1 General Operating Procedures
The Browne 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
2.29
day, with the greatest releases being made during daytime periods of peak
load. During off-peak periods, the plant discharge will vary depending on
system requirements but will never fall below a minimum discharge require-
ment. The reservoir level will vary on a seasonal basis as a function of load
characteristics and available 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 scheduled outage rate for the plant is estimated to be an average of
5 days per year per unit over the 1 ife of the project.
Power Output and Project Operation Characteristics
A hydropower simulation study was performed for the Browne project by
Acres American, Inc (1981). This study involved utilization of a reservoir
and power plant model that simulated the operation of the project on a monthly
basis for the 23-year period of hydrologic record. As discussed in Sec-
tion 2.1, the Acres American study generated monthly inflows for the damsite
using recorded flows from the USGS streamgage on the Nenana River near Windy.
To provide an independent check to the Acres American study, Ebasco performed
a similar operation study using the 29-year period of record of the USGS gage
near Healy as a basis for developing monthly inflows at the project site. As
indicated in Section 2.1, it was felt that the recorded streamflows at Healy
were more appropriate than those from the Windy gage in view of the fact that
the drainage area of the Healy gage is closer in size to the damsite than that
of the Windy gage, and the period of record of the Healy gage is longer.
Several parameters used in Ebasco's simulation study were obtained directly
from the Acres American study. These include storage-elevation data, maximum
and minimum storages, average tailwater level, minimum downstream release
requirements, monthly demands, load factor, the discharge coefficient, and
average overall efficiency. The results of Ebasco's operation study have
2.30
been utilized herein as a basis for estimating the power output and opera-
tional characteristics of the project.
On an average annual basis, the reservoir level will vary between the
normal maximum level of elevation 975 feet and a minimum of elevation 919 feet,
with the average reservoir level being elevation 956 feet. The estimated
average tailwater level at the Nenana River at the powerhouse site is eleva-
tion 780 feet, which provides an average gross power head of 176 feet. The
monthly variation in reservoir level during an average year of operation is
shown in Table 2.4. Based on the results of the power operation studies for
the period of record, the estimated average annual energy is 430,300,000 kWh,
which compares favorably to the value of 408,091,000 kWh obtained from the
Acres American study. The annual firlTI energy obtained from Ebasco's operation
study is 297,660,000 kWh, which ;s approximately 27 percent greater than the
value obtained from the Acres American study. This difference is due to the
difference in dry year streamflows between the two models of estimated monthly
streamflow at the site.
TABLE 2.4. Reservoir Operation During Average Year
Average Reservoir
Month Elevation (feet)
October 975
November 969
December 959
January 949
February 939
March 928
April 919
May 936
June 972
July 975
August 975
September 975
Annual Average 956
2.31
The plant discharge into the Nenana River will vary from a maximum of
approximately 8,400 cfs, under conditions of maximum reservoir level and power
output, to a minimum of 700 cfs during offpeak hours.
2.6.3 Plant Life
The economic life of the project is estimated to be 50 years.
2.6.4 Operating Work Force and General Maintenance Requirements
It is anticipated that the Browne project will be a remote-controllea
facility and will not require resident operating personnel. Weekly trips will,
however, be made to the plant to perform routine maintenance and inspection.
These weekly inspections could be performed by one or two operators. Major
overhauls and maintenance work will ordinarily be performea on an annual basis
by a larger crew.
Major components of the generating machinery are not expected to need to
be replaced during the life of the project. Repair 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 bearing and windings are other items that might 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, this may 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.
2.32
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 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 ~446.1 million.(a) The
equivalent unit capital cost is £4,461 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 58-month basis from
start of project 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
Materials and Construction
Equipment Labor
Year (Percent} (Percent}
1981 1.0 0.5
1982 1.2 1.7
1983 1.2 1.7
1984 0.7 1.3
1985 -0--0-
1986 -0.1 -0.1
1987 0.3 0.3
1988 0.8 0.8
1989 1.0 1.0
1990 1.1 1.1
19Y1 1.6 1.6
1992 -on 2.0 2.0
(a) January 1982 dollars, not including land or land rights, owner's costs or
transmission costs beyond the switchyard.
3.1
L
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
w 14. . 15 •
N
( a)
(b)
TABLE 3.1. Bid Line Items Costs for the Browne Hydroelectric Projecd a)
( January 1982 Dollars)
Construction Equipment
labor and Construction Operation Equipment Permanent Sub-Total
Bid line Item Insurance Su~~lies Cost Rent Materials Contracts Oi rect Cost
Improvements to Site 89,500 6,700 99,900 76,300 7,400 £7':t,8UO
Earthwork and Pili ng 18,581,000 17,781,000 31,384,200 21,121,400 47,966,500 240,000 137,074,100
Concrete 14,236,600 1,600,500 1,759,900 1,079,100 7,704,100 26,380,200
Structural Steel and lift Equipment 1,163,900 140,300 35,300 344,100 5,092,500 6,776,100
Buil dings 93,000 28,800 7,000 191,000 319,800
Turbine Generator 3,234,200 23,000 10,000 13,800,000 17 ,067 ,200
Other Mechanical fQuipment 258,200 22,400 75,000 652,000 1,007,600
Piping 782,600 28,800 15,000 950,000 1,776,40U
Instrumentation 62,300 2,300 500 50,000 115,100
Electrical Equipment 934,500 23,000 15,000 1,500,000 2,4n,500
Painting 301,800 34,500 15,000 220,000 571,300
Off-Site Facilities 7,705,100 2, 965, 400 9,715,000 7,612,5,00 20,484,300 48,482,300
Substation 603,600 11,500 5,000 1,700,OUO 2,320,100
Construction Camp Expenses 5,246,900 16,809,500 22 ,056,400
Indirect Construction Costs and
Architect/Engineer Services(b) 14,948,900 56,392,900 2,149,500 1,405,700 74,897,000
SUBTOTAL 68,242,100 95,870,600 45,143,800 31,781,600 100,317,800 240,000 341,595,900
Contractor's Overhead and Profit 44,500,000
Contingencies 60,000,000
TOTAL PROJECT· COST 44b,O!:l5,900
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. Also not included are the costs associated with removing approximately 8 miles of highway and 16 miles of railroad.
Includes ~44,500,OOO for engineering services and ~30,396,900 for other indirect costs, including construction equipment and
tools, construction related buildings and services, nonmanual staff salaries, and craft payroll related costs.
TABLE 3.2. Payout Schedule for Browne Hydroelectric Project
(January 1982 Dollars)
l.
2.
3.
4.
5.
6.
7.
8.
9.
10.
ll.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
27.
28.
29.
30.
3l.
32.
33.
34.
35.
36.
37.
38.
39.
40.
4l.
42.
43.
44.
45.
46.
47.
48.
49.
50.
51.
52.
53.
54.
55.
56.
57.
58.
Cost per Month,
0011 ars
3,561,500
3,718,300
4,060,300
6,314,200
6,314,200
6,892,700
6,838,300
6,838,300
6,838,300
4,584,300
4,481,900
4,481,900
4,481,900
7,720,500
7,720,500
9,947,200
9,947,200
9,947,200
9,947,200
9,947,200
7,720,500
7,720,500
6,193,200
6,193,200
6,193,200
10,209,800
8,615,900
13,741,300
13,741,300
13,741,300
13,741,300
13,741,300
11,514,500
11,514,500
4,599,400
4,599,400
4,599,400
9,974,400
9,974,400
11,564,900
11,564,900
11,564,900
11,564,900
11,564,900
11,564,900
11,564,900
5,173,900
5,173,900
5,173,900
5,207,300
3,936,800
3,936,800
3,936,800
3,936,800
3,936,800
3,936,800
3,936,800
3,943,100
3.3
Cumulative Cost,
Dollars
3,561,500
7,279,800
11,340,100
17,654,300
23,968,500
30,861,200
37,699,500
44,537,800
51,376,100
55,960,400
60,442,300
64,924,200
69,406,100
77 ,126,600
84,847,100
94,794,300
104,741,500
114,688,700
124,635,900
134,583,100
142,303,600
150,024,100
156,217,300
162,410,500
168,603,700
178,813,500
187,429,400
201,170,700
214,912,000
228,653,300
242,394,600
256,741,300
267,650,400
279,164,900
283,764,300
288,363,700
292,963,100
30'2, 937, 500
312,911,900
324,476,800
336,041,700
347, 606, 600
359,171,500
370,736,400
382,564,900
393,866,200
399,040,100
404,214,000
409,387,900
414,595,200
418,532,000
422,468,800
426,405,600
430,342,400
434,279,200
438,216,000
442,152,800
446,095,900
(including inflation) and subtracting a Gross National PrOduct deflator series
which is a measure of inflation.
3.2 OPERATION AND MAINTENANCE COSTS
3.2.1 Operation and Maintenance Costs
The annual operation and maintenance cost for the Browne hydroelectric
project, expressed in 1982 "Alaskan dollars," is estimated to be &480,000
(4.80 &/kW/yr). All operation and maintenance costs are assumed to be fixed
costs that do not vary appreciably with the plant's kilowatt-hour output.
3.2.2 Escalation
Estimated real escalation of fixed and variable operation and maintenance
costs are as follows:
3.3 COST OF ENERGY
Year
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
Escalation
{Percent}
1.5
1.5
1.6
1.6
1.7
1.8
1.8
2.0
2.0
2.0
2.0
Estimated busbar energy cost for the Browne hydroelectric project is
52 mills per kilowatt-hour. This is a levelized lifetime cost, in January
1982 dollars, assuming a 1990 first year of commercial operation, and full
utilization of the average annual power output of the facility. Estimated
busbar energy costs for lower capacity factors and later startup dates are
shown in Figures 3.1 and 3.2. These costs are based on the following
financial parameters:
3.4
Debt Financing-100%
Equity Financing 0%
Interest on Debt 3%
Federal Taxes None
State Taxes None
Bond Life 50 years
General Inflation 0%
The escalation factors given above were employed. Weighted average capital
cost escalation factors were derived using a labor/material ratio of 25%/75%.
f-
VI o u
>-(J
0::
UJ
Z
UJ
0:: «
to
VI
:::>
to
o
UJ
f-« :;;
f-
VI
UJ
90
80
60
so
40
30
20
10
o
o 10 20 30 40 SO 60 70 80
CAPACITY FACTOR (%)
FIGURE 3.1. Cost of Energy Versus Capacity Factor
(January 1982 Dollars)
3.5
90 100
.l:
3:
.:t:.
If>
E
f-
IJ')
0 u
>-
<..:l
0::: w z w
0::: < CO
IJ')
::J
CO
0 w
f-< ::E
f-
IJ') w
80
70
60
50
ijO
30
20
10
0
~ -
1990 1995 2000
YEAR OF FIRST COMMERCIAL OPERATION
FIGURE 3.2. Cost of Energy Versus Year of First Commercial
Operation (January 1982 Dollars)
3.6
-
2005
4.0 ENVIRONMENTAL AND ENGINEERING SITING CONSTRAI
Because it would be licensed by the federal government, the Browne hydro-
electric project would likely require the preparation of an environmental
impact statement. Council of Environmental Quality regulations implemented
pursuant to the National Environmental Policy Act of 1969 require that an
environmental impact statement include a discussion and evaluation of alterna-
tive projects. This requirement is usually satisfied tor hydroelectric proj-
ects through the evaluation of alternate sites, hydroelectric projects, and
often, evaluation of other energy generating technologies. The purpose of
such a study is to identify a preferred site and possibly viable alternative
projects to supply the required energy.
Presented in this section are many of the constraints that will be evalu-
ated during a siting study, with special attention given to their applicability
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; 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. Hydrological
impacts due to the change in flow regime and creation of a reservoir must De
identified and reviewed in the siting report. The resulting impacts on water
quality, espeCially suspended sediment and dissolved gases, must also be
evaluated.
4.1
At present, it does not appear that any of the above consioerations will
prove to be a significant constraint with the Brown hydroelectric project.
This will have to be confirmed during siting activities.
4.1.2 Air Resources
There may be some changes in microclimatology relating to the creation of
the reservoir. However, no significant environmental constraints relating to
air resources are anticipated.
4.1.3 Aquatic and Marine Ecology
An inventory of the species present in the river will need to be per-
formed, with emphasis on game fish, significant benthos, and aquatic vegeta-
tion supporting terrestrial life. Anadromous fish are not known to exist in
this portion of the river; however, this will need to be verified as the dam
will create a barrier to upstream and downstream migration. Identification of
threatened or endangered species, or significant game habitat, could constrain
project development. This is, however, not anticipated at the proposed
project location.
4.1.4 Terrestrial Ecology
Since habitat loss is generally considered to represent the most sig-
nificant impact on wildlife, the prime siting activity of the terrestrial
ecology group will be identification of important wildlife areas, especially
critical habitat of threatened or endangered species. Based upon this inven-
tory, potential restrictions on reservoir size and/or configuration may be
determined, together with preferred locations for access roads and transmis-
sion routes. At present, no significant terrestrial constraints are antici-
pated at the proposed location.
4.1.5 Socioeconomic Constraints
Major socioeconomic constraints center about potential land use conflicts
and community and regional socioeconomic impacts derived from the external
effects associated with project activities. Potential exclusionary land uses
include lands set aside for public purposes, areas protected and preserved by
legislation (federal, state or local laws), areas related to national defense,
4.2
areas in which a hydroelectric installation might preclude or not be com-
patible with local activities (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.
The proposed location does not appear to fall under the above constraints.
Regarding other socioeconomic concerns, minimization of the boom/bust
cycle will be a prime criterion. Through the application of criteria pertain-
ing to community housing, population, infrastructure and labor force, this
important consideration should be evaluated and preferred mitigative measures
identified. Due to the fact the site is close to several small communities,
and the project will require relocation of portions of the Alaska Railroad and
Anchorage-Fairbanks highway, socioeconomic criteria will be heavily weighted
in the overall site evaluation process.
4.2 ENGINEERING SITING CONSTRAINTS
The project contains two principal engineering constraints. Potentially,
the most significant constraint is that the dam foundation materials are not
well suited as impervious foundation. Published literature indicates that
surface deposits in the site area along the Nenana River consist of coarse
pervious sands and gravels. The depth of these deposits is not known with
certainty. At best, the dam foundation will require a considerable amount of
excavation of these materials beneath the impervious core to provide a
suitable water cutoff.
The second siting constraint is that the project is located within 25
miles of a major or seismically active fault zone. In 1947 an earthquake of
intensity VIII+ occurred 10 miles north of the proposed powerhouse location.
An earthquake of this size can be adequately designed for but will require
more costly and massive structures. High seismicity may also result in a
liquefaction of any fine sands that might be present beneath the dam or along
the reservoir slopes. However, the presence and extent to which liquefiable
soils exists is not known at this time.
4.3
5.0 ENVIRONMENTAL AND SOCIOECONOMIC CONSIDERATIONS
5.1 SUMMARY OF FIRST ORDER ENVIRONMENTAL IMPACTS
The construction and operation of a 100-MW 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. These primary effects are then analyzed and evaluated in light of
existing environmental conditions to determine the significance of the impact
and the need for additional mitigation measures.
5.2 ENVIRONMENTAL AND SOCIOECONOMIC EFFECTS
5.2.1 Water Resource Effects
The construction and operation of the Browne hydroelectric facility will
impact the hydrologic regime of the Nenana River. The construction of the dam
will create an 11-mile-long reservoir, changing a portion of the river from a
flowing water to a stillwater regime. This will tend to increase water losses
from the watershed through increased evaporation. In addition, creation of
the reservoir may change certain water quality parameters. The parameters
most likely experiencing change will be dissolved oxygen and temperature, due
to possible stratification in the reservoir; and suspended sediment, due to
change in flow. Dissolved gas concentration may change due to passage through
the spillway and penstock. Possible downstream erosion and/or sedimentation
may occur due to discharges from the tailrace. This effect, however, can be
minimized by proper design of the discharge structure.
5.2.2 Air Resource Effects
Since the anticipated reservoir will be relatively small, no noticable
meteorological changes in the immediate vicinity are anticipated. Hence, no
effects to the air resource are expected.
5.1
TABLE 5.1. Primary Environmental Effects
Air no first order impacts
Water
Land
Streamflow Regulation
Water Quality
Pl ant Site
Plant Access
Transmission
Relocations: Road
Socioeconomic
Construction work force
Operating work force
Relocations
Average: 3800 cfs
Maximum: 8400 cfs
Minimum: 700 cfs
To be determined during siting activities;
impacts anticipated to be decreases in down-
stream suspended sediment and increases in
downstream dissolved gas concentration
Approximately 16 square miles
Approximately 3.5 miles of road
Approximately 3.5 miles of 138-kV overhead line
Approximately 8 miles of highway
Approximately 16 miles of railroad.
Peak requirements of approximately 515
1-2 operators for weekly inspection
None
5.2.3 Aquatic and Marine Ecosystem Effects
There are no reported anadromous fisheries in the project area. Hence,
there will be no impact to important commercial species. However, grayling,
burbot and possibly dolly varden (arctic char) exist in the project area,
based on the best available information. The dam will act as a barrier,
preventing upstream and downstream migration. It is uncertain whether the
creation of a reservoir will enhance or impede these populations. Baseline
data will be required to assess this impact. Benthic commmunities will likely
shift from those favoring a high energy (flowing stream) environment to those
favoring a low energy (reservoir) environment.
5.2
5.2.4 Terrestrial Ecosystem Effects
The primary potential wildlife impacts of the hydroelectric aeve10pment
will be from river level fluctuations and habitat loss. River level fluctua-
tion and creation of the reservoir may have a minor impact on the black and
brown bear feeding patterns, as well as on the vegetation that is used by
moose and the winter range caribou. There is a fairly low density of
waterfowl in the area; therefore, these species are not expected to be
significantly impacted. Creation of access roads may result in a loss of
habitat.
5.2.5 Socioeconomic Effects
The construction and operation of a hydroelectric plant has a high poten-
tial to cause a boom/bust cycle on surrounding small communities, causing
significant impact on community infrastructure. This impact can be mitigated
to some degree by drawing the work force from the more distant, larger com-
munities of Nenana and Fairbanks. The installation of a construction camp
will not mitigate the impacts on the social ana economic structure of the
surrounding small communities.
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 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 Rai1be1t. The
breakdown 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.
5.3
6.0 INSTITUTIONAL CONSIDERATIONS
This section presents an inventory of major federal, state of Alaska, and
local environmental regulatory requirements that will be associated with the
development of the Browne hydroelectric project. The discussion of this
inventory is divided into three subsections that set forth feaeral, state, and
local environmental requirements, respectively.
6.1 FEDERAL REQUIREMENTS
A hydroelectric project is not subject to many environmental regulatory
programs that are applicable to a fossil fuel-fired power plant. For example,
a hydro project may be exempt from the National Pollutant Discharge El imina-
tion System (NPDES) permitting program that is operated for Alaska by the
Environmental Protection Agency (EPA) pursuant to section 40~ of the Clean
Water Act. The NPDES permit applies to discharges from a "point source." As
this term is defined (40 CFR 122.3) it is unclear whether the Browne hydro-
electric project will include a point source discharge into navigable waters,
as EPA generally does not require NPDES permits for hydroelectric projects if
water merely passes through a turbine from the reservoir to the receiving
waters. However, an NPDES permit may be required if during construction of a
dam, water is discharged from settling basins, or if floor drains, sanitary
systems, etc., are discharged during operation. This issue can only be
resolved with the development of additional information regarding project
design.
On the other hand, a hydroelectric project is subject to some environ-
mental regulatory programs not applicable to a fossil fuel-fired facility. The
most important of these, which could have a substantial impact upon the
licensing schedule, is the license that must be obtained by each individual
who wishes to construct a water power project of more than 2000 horsepower
installed capacity. These licenses are issued by the Federal Energy Regula-
tory Commission (FERC) as requirea by the Federal Power Act (16 USC 792-828c).
FERC issues these licenses according to the regulations in 18 CFR 4.
6.1
An application for a FERC license for a new project is quite complicated,
requiring the preparation of seven exhibits (18 CFR 4.41). 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 water for power
production (18 CFR 4.41 Exhibit D). This is accomplished by showing that
state permits have been obtained, and that the state has certified that water
quality will be maintained as is required by section 301 of the Clean Water
Act. As a result, submission of a complete FERC permit cannot occur prior to
receipt of those permits and certification. Furthermore, the FERC review
process is lengthy, even after submittal of 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, which FERC cannot approve
before the applicant has submitted its environmental report (18 CFR 4.41
Exh'ibit) 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, 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, a hydroelectric project will be 'subject
to some specialized permits required in Alaska, such as the state dam permit
and water use permit issued by the Alaska Department of Natural Resources and
the permit to interfere 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
6.2
Agency
Environmental
Protection Agency
U.S. Army Corps of
Engineers
Federal Energy
Regulatory
Commission
National Marine
Fisheries Service/
Fish and Wildlife
Service
Advisory Council
on Historic
Preservation
All Federal
Agencies
TABLE 6.1. Federal Regulatory Requirements
Requirement
National Pollutant
Discharge Elimination
System
Construction Activity
in Navigable Water
Discharge of Dredged
or Fi 11 Materi al
Environmental Impact
Statement
License for Major New
Hydropower Project
Threatened or
Endangered Species
Review
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
Scoee
Di scharges to
Water
Construction
Water
Discharges to
Water
A 11 Impacts
Construction
Hydropower
Project
Air, Water,
Land
Land Use
Land Use
Development
in Wetlands
Development
in
of
in Floodplains
Statute
or Authorit.l:
38 USC 1251
et ~.;
section 1342
33 USC 401
et seq.;
section 403
33 USC 1251
et ~.;
section 1342
42 USC 4332
section 102
16 USC 792
et ~.
16 USC 1531
et ~.
16 USC 402 aa
et ~.
16 USC 416
et ~.
land (due to preservation of the land by state government or native Alaskans)
under one of several special programs. The state requirements are summarized
in Tab 1 e 6.2.
Agency
Alaska Department
of Environmental
Conservation
Alaska Department
of Natural
Resources
Alaska Department
of Fish and Game
TABLE 6.2. State Regulatory Requirements
Reguirement
State Certificate that
Discharges Comply with
CWA and State Water
Quality Requirements
Solid Waste
Di sposa 1 Permit
Permit to Interfere
With Salmon Spawning
Streams and Waters
Water Use Permit
Rights-of-Way Easement
Dam Permit
Anadromous Fish
Protection Permit
Critical Habitat
Permit
Fishways for
Obstruction to
Fish Passage
6.4
Scope
Discharges to
Water
So 1 id Waste
Construction in
Water
Appropriation
of Water
Right of Way
on State Lands
Construction of
Dam 10 Feet
High or More
Statute
or Authority
33 USC 1257
et ~.;
section 1341
Alaska
Statute
46.03.100
Alaska
Statute
Alaska
Statute
46.15.030-185
11 Alaska
Administrative
Coae 58.200
Alaska
Statute
Fi sh Protection· Alaska
Fish and Game
Protection
Fish Protection
Statute
16.05.870
Alaska
Statute
16.20.220
and .260
Alaska
Statute
6.3 LOCAL REQUIREMENTS
The Browne Hydroelectric project, located on the Nenana River near browne,
south of Fairbanks, will be located in an unorganized region in which no local
permitting requirements or land use restrictions have been identified.
6.5
7.0 REFERENCES
Acres American, Inc. 1981. Susitna Hydroelectric Project -Development Selec-
tion Report -Subtask 6.05. Alaska Power Authority, Anchorage, Alaska.
Commonwealth Associates, Inc. 1981. Feasibility Study of Electrical Inter-
connection Between Anchorage and Fairbanks. Engineering Report R-2274,
Alaska Power Authority, Anchorage, Alaska.
7.1