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HYDROPOWER POTENTIAL
OF
BEAR CREEK
FOR
HOPE, ALASKA
OCTOBER, 1984
Alaska District
U.S. Army Corps of Engineers
Pouch 898, NPAEN-PL-P
Anchorage, Alaska
qEPL.; ro,
o\TTENTtQN Of:
DEPARTMENT OF THE ARMY
U.S. ARMY ENGINEER DISTRICT, ALASKA
POUCH 898
ANCHORAGE, ALASKA 99506-0898
Plan Formulation Section
December 7, 1984
NOTICE OF COMPLETION OF NEGATIVE FEASIBILITY
REPORTS FOR HYDROELECTRIC POWER
AT FOUR ALASKA LOCATIONS
I am announcing completion of reports on potential hydroelectric
power generating facilities at four Alaska locations: Anaktuvuk
Pass, Kaktovik, Hope, and Seldovia. In all cases, after careful
investigation and evaluation, I found that Federal development of
the facilities is not feasible at this time.
All of these potential projects would require supplementation with
other sources of electricity during the winter, when flows of
Alaskan streams dwindle and when demand for electrical power is
greatest.
The four locations were studied pursuant to a resolution of the
U.S. Senate Committee on Public Works dated October 1, 1976,
directing the Corps of Engineers to determine the feasibility of
installing small hydroelectric plants in isolated Alaskan
communities. The studies evaluated future needs for electrical
power at each of the sites and alternatives available to meet those
needs. While the Corps had primary responsibility for conducting
the studies, numerous other Federal, State, and local agencies and
groups contributed. A public involvement program was maintained.
All sites were identified in regional reconnaissance studies
performed by engineering firms under contract. The Corps conducted
followup field investigations. Each location is briefly described
below.
Anaktuvuk Pass: This community is in a mountain valley in the
central Brooks Range above the Arctic Circle, 250 miles
north-northwest of Fairbanks. The present diesel facilities for
electrical generation are 01-med and operated by the North Slope
Borough. The optimum project was found to be a run-of-river system
on Inukpasugruk Creek with a 22-foot-high rockfill dam and 3,250
feet of steel penstock. Its single turbine would have a total
capacity of 200 kilowatts (kW). The creek would have sufficient
streamflow to produce power during about 4 months of the year. The
project I'Jould cost about $6 million and would have a benefit-cost
ratio of 0.3 to 1. (A ratio of greater than 1 to 1 is required to
• • meet Federal economic evaluation criteria.) The total cost of
using this hydroelectric project in conjunction with the town
diesel system exceeds the cost of continuing to generate·power with
the diesel system alone.
Kaktovik: This village is located on Barter Island in the Beaufort
Sea just off the north coast of Alaska. The island is separated
from the coast by a narrow 1 a goon. A hydropower reconnaissance
study using existing topographic maps of northeastern Alaska found
that a site on the Okpilak river near Kaktovik might be marginally
feasible. Corps field investigation determined that this site is
founded on an alluvial deposit and the stream bank provides no
suitable dam or diversion site. The stream gradient is gradual,
approximately 25-40 feet per mile; thus an extremely long penstock
would be required. Due to the long winter season, sufficent
streamflow to produce power would be available only 4 months of the
year. Study of the site was terminated because of lack of
technical feasibility for hydropower development.
Hope: Hope is situated in Southcentral Alaska, on the south side
of Turnagain Arm about 25 air miles south of Anchorage. The
community currently receives single phase power produced by gas
turbines from Chugach Electric Association (CEA), which operates a
1 arge network that serves Anchorage and other towns in the area.
Tying the proposed hydropower plant into the existing CEA grid was
found to be more economical than using its output only for the
communities along the Hope feeder line, since the plant could not
meet the full feeder line demand in winter. Three dam sites on
Bear Creek near Hope were considered. The lowest one would be
optimum, due to considerably higher penstock and road improvement
costs for the upper sites. The run-of-river project evaluated for
this site would include a gabion diversion structure 6 feet high
and a polyethylene penstock 1,640 feet long. Six plant sizes were
considered; the one selected would have two turbines with a total
capacity of 150 kW. The project would cost about $1.5 million and
would have a benefit-cost ratio of 0.3 to l. The costs would
exceed the benefits by $97,000 per year.
Seldovia: Seldovia is located on the west coast of the Kenai
Peninsula, 16 miles southwest across Kachemak Bay from Homer.
Electrical power is currently supplied to Seldovia by Homer
Electric Association (HEA), which purchases the power from CEA. A
project site on Windy River was selected. The run-of-river project
analyzed for this site would have a rockfilled bin diversion
structure 8 to 10 feet high and 3,420 feet of penstock, part
polyethylene and part steel. The single turbine would have a
capacity of 590 kW. Failure of the transmission line from Homer
causes frequent power outages, especially in winter; the community
then uses d i ese 1 generators provided by HEA. Some of these power
losses may be avoided with a hydropower project, although low
stream flows during the winter would limit potential hydropower
production available from the Windy River. The project would cost
2
about $5.2 million and would have a benefit-cost ratio of 0.6 to
1. It is not economically feasible for Federal construction at
this time.
Please pass this information on to others interested in these
reports who may not have received this notice.
Further information on any of the above studies may be
from my office or from Mr. Carl Borash, Chief of
Formulation Section, Post Office Box 898, Anchorage,
99506-0898. The telephone number is (90 75 2632.
Saling
Colonel, Corps of Engineers
District Engineer
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FOUR LOCATIONS INVESTIGATED FOR HYDROELECTRIC POWER
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HYDROPOWER POTENTIAL OF BEAR CREEK FOR HOPE, ALASKA
SUMMARY
The Alaska District, U.S. Army Corps of Engineers, investigated the
hydropower potential for Hope, Alaska. Those sites along Bear Creek near
Hope were studied, and one site was selected for further evaluation. A run-of-
river project evaluated for this site would feature two turbines with a total
capacity of 150 kilowatts. Due to low winter streamflows, the project could
not produce a dependable capacity year-round. An annual average of 767,000
kilowatt-hours (kWh) could be fed into the Chugach Electric Association
feeder line serving the Hope area. The project would cost about $1.5 million,
or $141,000 annually, and would provide about $44,000 of benefits each year.
The costs exceed the benefits by $97,000 per year.
PERTINENT DATA SHEET
General Data
Project Installed Capacity (kW)
Number of Units
Diversion Height (ft.)
Penstock Type
Penstock Length (ft.)
Penstock Diameter (in.)
Allowable Penstock Pressure (psi)
Transmission Line Length (miles)
Access Road Length (miles)
Gross Head {ft.)
Design Net Head (ft.)
150
2
6
High Density Polyethylene
1,640
18
125
1
1.3
210
195
Average Annual Energy (MWh)
Average Annual Usable Energy (MWh)
767
767
Economic Data (50 Years, 8-3/8 Percent Interest, 1984 Prices)
Project First Cost
Investment Cost
Annual Cost
Annual Benefits
Annual Net Benefits
Benefit-Cost Ratio
~ l ,449,000
$ 1,538,000 s 141,000 s 44,000 s -97,000
0.31
CONTENTS
Introduction
Study Area
Historic and Projected Energy Use
Site Information
Site Inspections
Site Description
Land Ownership
Water Use and Hydrology
Mineral Claims
Environmental
Design Considerations
Layout of Facilities
Diversion/Intake Structures
Penstocks
Powerhouse Layout
Generation Facilities
Access
Transmission
Energy Analysis and Plant Selection
Energy Potential of Bear Creek
Selected Damsite
Selected Plan
Economics
Benefit Analysis
Cost Analysis
Evaluation
Conclusions and Recommendations
Page
1
1
4
5
5
5
8
8
9
10
11
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11
11
15
15
16
16
18
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19
20
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26
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Figure No.
1
2
3
4
5
6
7
8
Table No.
l
2
3
LIST OF FIGURES
Title Page
Location and Vicinity Maps 2
Projected Energy Demand, CEA Hope Feeder Line 6
Peak Discharge Frequency, Bear Creek 9
Facilities Layout 12
Diversion and Intake (Typical) 13
Alternative Diversion and Intake 14
Net Benefits 19
Energy Demand versus Energy Potential, Damsite 3 20
LIST OF TABLES
Bear Creek Average Monthly Flows
Summary of Damsi te Options
Summary of Project Features (Damsite 3)
8
18
20
HYDROPOWER POTENTIAL
OF
BEARCREEK
FOR
HOPE, ALASKA
OCTOBER, 1984
INTRODUCTION
The evaluation of small hydroelectric systems was authorized by a
1 October 1976 United States Senate Public Works Committee Resolution
which directed the U.S. Army Corps of Engineers to determine the feasibility
of installing small prepackaged hydroelectric units in isolated Alaska
communities.
In 1982, a regional inventory for small hydropower projects in
Southcentral Alaska was completed. This inventory analyzed more than 30
sites, recommending nearly 20 for more detailed examination, including the
Bear Creek site near Hope. The Bear Creek site was one of six selected by the
Alaska District from this group for field reconnaissance and additional
analysis.
STUDY AREA
Location. Hope is situated iC the southcentral region of Alaska, on the south
side of Turnagain Arm at 60 55' 15 11 N. latitude, 149° 38' 30" W. longitude. It
is about 25 air miles south of Anchorage, and nearly 60 air miles northeast of
Kenai. The community of Hope is located in the general area of the mouth of
Resurrection Creek. The community of Sunrise is located about 9 miles from
Hope on the Hope Highway. Homes and cottages are scattered along the Hope
Highway. In addition to dwellings and some small businesses a State
Department of Transportation shop is located at Silvertlp, near the junction of
the Hope and Seward Highways.
Public Services. A summary of the various public services in Hope is provided
below.
Government. Hope, which is the largest community along the Hope Highway
and serves as a center, is classified as an unincorporated community, with no
formal structure of government overseeing the affairs of the area. All
responsibilities for planning, zoning, area education, providing other public
services, etc., are maintained by the Kenai Peninsula Borough. Input into the
borough's planning process for Hope is provided from members of the Hope
Community Council.
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Police Protection. Police protection for the community is provided by the
Alaska State Troopers stationed in Girdwood. Troopers visit the area
frequently, as the access road to the community is part of the state highway
system.
Health Facilities. There are no health facilities available in Hope. Most
medical treatment needed by local residents is obtained from health facilities
in Anchorage. Emergency cases can be evacuated by air to hospitals in
Anchorage.
Education Facilities. Education in Hope is provided for students in grades
K-12. The local school currently consists of a one-room schoolhouse.
However, a considerably larger two-room school is expected to be started by
1985. Enrollment at the school has fluctuated only slightly, ranging from
about 15 to 20 in recent years.
Transportation. Hope is accessible to Anchorage and Kenai Peninsula
communities by means of the Hope Highway, which connects to the Seward
Highway. It requires approximately 2.5 hours to travel the roughly 90 road
miles between Anchorage and Hope. In 1980 and 1981 general road
improvement upgraded the 18 miles of highway from the Silvertip turnoff to
Hope and extended road access to about 20 picnic and camp sites in the area.
A small runway about one mile from Hope can accommodate light aircraft;
however, no regularly scheduled air service is available to the community.
Boat traffic in the Hope area is limited and dangerous due to mud flats and
extreme tidal action in Turnagain Arm. The Resurrection Trail is well known
by hikers as a 30-mile trail from Hope to Cooper Landing on the Sterling
Highway.
Human Resources
Demographic Data. The population in the Hope area has fluctuated fairly
widely over the years, as evidenced from decennial population counts by the
Census Bureau. The lowest recorded count was in 1930, when 15 persons were
reported. The 1980 count of 103 was the highest. Local estimates indicate a
1983 population of 120. Population fluctuation in past years was mostly
attributed to the availability of mining jobs in the area. In recent years the
community has attracted people seeking a more relaxed, rural type lifestyle.
The table on the following page indicates 1920 to 1980 census counts taken in
Hope.
Year
1920
1930
1940
1950
1960
1970
1980
U.S. Census Population Counts
Hope, Alaska
1920-1980
Population Percentage Change
44
15
71
63
44
51
103
-3-
-65.9%
+373.3
-11.3
-30.2
+15.9
+1 02.0
The 1980 census statistics show that 91 percent of the population in
Hope were white, 3 percent were Alaska Natives, 3 percent were Asian and
Pacific Islanders, and 3 percent were classified as "other".
Em lo ment. The economy of · Hope is based mainly on the
recreationa tourist trade of fishermen, hikers, backpackers, campers, and
placer gold miners. A cafe, a small store, a bar, a sawmill, a log cabin kit
manufacturing plant, and three campgrounds are located in Hope/Sunrise.
Several Anchorage residents maintain recreational cabins in the area. Most
residents travel to Anchorage or Seward to shop, to purchase fuel, and to
obtain supplies. Virtually all area businesses are owner operated and create
essentially no additional employment. Because of the area's remoteness and
long term objective to maintain a quiet rural type of lifestyle, no significant
business growth is anticipated in the near future.
Future Development. In recent years (1980-81} the highway development
program for the Kenai Peninsula has provided improved and maintained year-
round access to the community of Hope. The general area has a strong
attraction for summer tourists, hikers, miners, and campers. Some increase in
the lumber industry can be expected to satisfy the area demand for precut log
homes and cabins. Community leaders generally support the claim that
tourism and summer recreation will continue to be the main attraction in the
foreseeable future.
HISTORIC AND PROJECTED ENERGY USE
Hope currently receives single phase power from Chugach Electic
Association (CEA) produced by gas turbines. Energy costs to the consumer
vary between 8 and 10 cents per kilowatt-hour (kWh) depending on the quantity
used and the area served. These rates (January 1984} were implemented
following a 1983 Alaska Public Utilities Commission directive to equalize
rates throughout the southcentral region. This rate may not reflect the actual
cost of serving long distance and small consumers.
According to CEA, about 90 percent of the energy sales in Hope were for
residences and 10 percent were for small commercial ventures. There are
about 60 active electric meters in Hope, of which 51 are residential. About 15
residences have small privately owned standby gasoline generators of the 2-to
5-kilowatt size. A sawmill and adjacent log home are powered by their own
250 kW three-phase diesel generator and are not connected to CEA lines.
There are an estimated 10 additional buildings in Hope that are not presently
being served by CEA. During 198.3, 976 MWh of energy passed through the
Hope substation. Line losses accounted for 5 percent or 49 MWh; Hope used 63
percent or 615 MWh; Sunrise used .30 percent or 29.3 MWh; and the State
highway maintenance shop used 2 percent or 19 M Wh •
A 50-kW standby diesel generator is maintained at Hope by CEA to
provide power should service be interrupted. In recent years outages have
been avoided by a combination of tree management along the feeder line and
unusually mild winters.
-4-
Most dwellings in Hope and Sunrise are heated with either wood or oil.
There may be some use of liquefied natural gas for space heating as well as
cooking. No use of waste heat is known. Gasoline for autos, recreational
vehicles, and machinery is stored in personal bulk tanks because the nearest
gas station is 2.5 miles away. There are no known wind generation systems in
town.
Increased energy demand by current users, and demand by new homes
and existing homes not currently using CEA service, have been considered in
the three future demand scenarios shown in figure 2. The medium case
represents the projected electrical energy demand assumed most likely to
occur, and yields an annual equivalent demand for the project life (1990-2040)
of 1,1.50 MWh. The energy demand forecast is based on the demand trend in
recent years, with consideration given to the population trend and factors
governing the economic growth. CEA has forecasted area-wide growth of
energy demand but has not given particular attention to Hope, realizing that
its growth would be negligible in relation to the large growth expected in much
larger communities, especially Anchorage. Construction of a hydroelectric
project at Hope would not be expected to alter this projection unless the
project substantially lowered costs to local power consumers.
The monthly distribution of energy demand is expected to remain
essentially unchanged. The expected increased demand attributed to new
connections by new weekend cabins and possible new demand by the existing
sawmill, which currently produces its own power, may tend to increase the
usage during the warmer months. This increased demand during the warmer
season is not expected to significantly offset expected increased demand by
year-round residences owned by persons employed in support services and
businesses. Year-round residents would tend to use much more electricity
during the winter months than would typical residents during the summer
months.
SITE INFORMATION
Site Inspections
The Bear Creek site has been visited by interdisciplinary study teams
from the Alaska District on the following occasions:
31 August 1982
31 August 1983 (semipermanent stream gage installed)
17 October 1983
On 27 April 1984, a team composed of Alaska District and S &: S Engineers,
Inc., personnel visited the site and serviced the stream gage installation.
Site Description
The uppermost diversion site (at about 1,350 feet elevation) is 8,250 feet
upstream of the railroad cars used as a reference datum. The railroad cars are
4,155 feet upstream of the paved Hope Highway and approximately one mile
east of Hope and are accessible by a 12-foot wide gravel road. Estimated head
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FIGURE 2
PROJECTED ENERGY DEMAND, CEA HOPE FEEDER LINE
-6-
(as measured on the 29-31 August &3 field trip) is approximately 700 feet
above the powerhouse site, or 740 feet above the railroad cars. Graywacke
bedrock outcrops flank each side of the stream. Ledgerock is estimated 2 to 4
feet below creekbed gravels. Although moderately fractured, these abutments
could support a structure of sufficient size for this project. Some remedial
treatment for lateral seepage control would be required.
Rock is available on or near the site, salvaged from sorted piles of
boulders removed from earlier placer mining operations. The potential
diversion sites are narrow. Full crest overflow spillways would therefore be
practical. Sediment and ice would be important considerations for all sites if
year-round operation is expected.
A second diversion site is located 1,250 feet downstream of the first
(7 ,000 feet above the railroad cars). Estimated head lost between these sites
is about 120 feet (stream gradient about 10% overall). This site is again
between graywacke abutments, nearly vertical for about 25 to 40 feet.
A large avalanche runout zone would be crossed by development of
either of the above sites. This zone extends from between 2,900 and 3,400
feet above the railroad cars. Vegetation is primarily grasses with small stands
of alder and intermittent young (less than 5-foot) trees.
At the downstream side of this avalanche zone a third potential diversion
site exists. This site is approximately 2,700 feet above the railroad cars, with
an estimated 250-foot head difference (21 0 feet to the powerhouse site). A
good road leads to this point. Rock (hard, brittle,massive graywacke with
moderate fractures) abutments are about 25 feet apart at water level, 35 feet
apart 5 feet above the water, and 50 feet wide 15 feet above the water. A
debris dam at this point traps an estimated 5 feet of sediment. There is one
small (50-foot-wide) avalanche chute below this site. It is revegetated and
contains a number of spruce trees which appear to be approximately seven
years old.
For the most part the access (century-old wagon) trail up the right bank
has a revegetated cut bank. Possible placement of the penstock beneath this
bank would afford a substantial degree of protection from avalanche potential.
There is no undercut bank in the large runout zone noted previous! y. Complete
burial of the pipe would probably be required at this point, since a roadbed
must also be prepared in lieu of the footpath. The remainder of the trail could
be upgraded to serve as an access road and a penstock corridor.
The first 1/2 mile above the railroad cars is essentially a 12-foot travel
surface, except in a short reach where placer operations have encroached.
The remainder is an overgrown trail of between 3 and 6 feet in travel width.
Grade is essentially gradual (about 10%) with three short locations with grades
of between 15 and 25 percent. The moderate cover of spruce, birch, and alder
trees would require clearing to widen the access trail. All tributaries to Bear
Creek are small enough to be crossed with culverts. No major structures
would be required for construction access.
-7-
Land Ownership
The entire project would be located within Chugach National Forest
boundaries and existing right-of-way and electrical easements. A Special Use
Permit from the U.S. Forest Service would be required to construct and
maintain a hydropower project.
Water Use and Hydrology
Records obtained from the State of Alaska's Department of Natural
Resources (DNR) indicate that there are currently five permits to appropriate
water from Bear Creek. Of these, only two are upstream of the powerhouse
and might therefore affect project feasibility. One permit is for 6 cfs, 365
days/yr, for hydropower generation, and would be diverted within NW}f. SW}f.
Section 1, which is the vicinity of the upper damsite. The other permit is for
1.3 cfs, April through December, for placer gold mining operations, and would
be diverted within SW~ NW~ Section 35, T ION, R2W, S.M., which is probably
downstream of, but could be just upstream of, the powerhouse. The remaining
four permits amount to 0.6 cfs and would not affect project feasibility since
the water used for the Bear Creek hydropower project would be returned to
the creek and would still be available to the permit holders. Monthly flows
averaged over the period of record are listed in table 1 for each of the
damsites. The data indicates that no flow at all may be available to the Bear
Creek project during some months since the existing water rights upstream are
in excess of the flow available. If the permit holder of 6 cfs does not
construct a hydropower plant by 1988 the permit will expire. A transfer of
rights is possible, with approval from the DNR, but under no circumstances
could the rights be sold. Figure 3 shows peak discharge frequencies for the
three sites.
TABLE 1
BEAR CREEK AVERAGE MONTHLY FLOWS, cfs
Damsite 111 Damsite 112 Damsite 113
JAN 2.4 2.5 3.1
FEB 2.1 2.2 2.7
MAR 1.8 1.8 2.3
APR 2.0 2.1 2.6
MAY 8.3 8.6 10.8
JUN 19.3 20.1 25.0
JUL 17.8 18.6 23.3
AUG 9.9 10.4 13.0
SEP 7.6 8.0 10.0
OCT 7.9 8.3 10.4
NOV 4.7 4.9 6.1
DEC 3.1 3.3 4.0
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FIGURE ! , PEAK DISCHARGE FREQUENCY, BEAR CREEK
Mineral Claims
Active mining claims along Bear Creek extend from Hope Road upstream
to beyond the upper damsite and encompass all land adjacent to the channel.
Claims are typically 1,320 ft. in the direction of the creek and 660 ft. across.
Uplands are also being mined, the extent of which varies from 800 to 2,000 ft.
left of the creek and from 300 to 1,000 ft. right of the creek. The miners are
entitled to all subsurface rights as long as they adhere to Federal and State
mining laws and perform and record the annual assessment work. The surface
rights, however, are retained by the public and are administered by the
Federal Government.
-9-
Environmental
Bear Creek, 5 miles long, runs from the mountains above Hope to tidewater at
Turnagain Arm •. Its width varies between 10 and 20 feet.
Most of the vegetation along the creek at the proposed diversion sites can be
classified as subalpine shrub and herbaceous. Alder thickets lie close to the
creek throughout its course. Below approximately 1,300 feet mean sea level
(msl), large stands of cottonwood, birch, and hemlock join alder in lining the
stream. The powerhouse area and penstock routes are in coastal spruce-
hemlock forest.
The creekbed is composed mainly of gravel and cobble, with coarse sand filling
the interstices. Years of heavy placer mining operations have altered the
stream, even changing its channel. These operations continue at present. In
some locations sediment has been deposited 6 feet deep, causing diversion of
the stream in summer. This diversion encroaches on private property and
some small parcels of agricultural land. Other impacts of placer mining
include reduction of the fishery resource and degradation of water quality.
The upper portion of Bear Creek flows year-round; however, the lower part
ceases to flow on the surface in winter. A field investigator recently found
the lower portion of the creek, from the mouth to 0.2 river-miles upstream, to
be completely dewatered with the gravel streambed exposed. Streamflow
upstream of this stretch indicated subterranean flow. This dry surface
condition occurs primarily during November through April. Lower reaches of
the creek, below the powerhouse location, are choked by sand and gravel,
causing the water to overflow its banks and braid before flowing into the tidal
flats.
The Alaska Department of Fish and Game (ADF&G) considers Bear Creek
important for the migration, spawning, or rearing of anadromous fish, tagging
it State Anadromous Fish Stream No. 274-60-10160. ADF&G surveys report
that Bear Creek supports pink and coho salmon and Dolly Varden throughout
its length. However, adult pink salmon were collected only in the tidal flats
near the clogged stream channels leading to the creek's mouth.
Wildlife signs along the creek are not abundant. Bear tracks were observed,
but they were limited to the tidal flats and the footpaths leading to the
potential diversion sites. Bear droppings were observed once in the upper part
of the study area. Moose seats and tracks were found in the upper part of the
area, but little evidence of winter browsing was seen. Both moose and bear
have been heavily hunted in the area; mountain goat and Dall sheep are no
longer commonly found. Small mammal use of the creekside appears limited.
Major environmental impacts would not be expected to result from
construction of a diversion structure, a penstock, a powerhouse, or a
transmission line at the Corps of Engineers' preferred sites, since the area is
already heavily impacted by placer mining operations. To minimize
disturbance to fish and wildlife, erosion control, revegetation, and
construction timing measures would be warranted.
-10-
DESIGN CONSIDERATIONS
Layout of Facilities
Three potential sites have been investigated. All three would be run-
of-river facilities, with gross head varying from 700 to 210 feet. All sites
have feasible penstock routes which could be combined with access roads. The
relationship of the facilities is shown in figure 4. The powerhouse site would
be in the floodplain approximately at the end of the existing gravel service
road.
Diversion/Intake Structures
Structures at all three sites would be gabion diversion structures. The
broad base of this type of gabion structure, along with the gabion's inherent
combination of flexibility and stability, would provide good protection against
ice forces (see figure 5). Manhole-type intakes would be set with intake levels
approximately one to two feet below the dam height. Trashrack covers for the
intakes would be installed to prevent clogging by debris; additionally, by
keeping the intake elevations sufficiently below the dam, most debris would
stay on the surface and be carried past the intake. A maximum dam height of
approximately 6 feet would be required for the largest penstock and was
assumed in all cases. Frazil ice conditions should be further investigated if
the project progresses to the design stage.
At the lowest site (site 3), due to the potential for frazil ice and debris, an
infiltration gallery and low concrete dam (see figure 6) were considered. The
hydraulics of this installation, however, indicated that a gallery the full width
of the stream and at least 200 feet long would be required to provide the range
of penstock flows assumed at this site. The steep natural gradient and massive
bedrock at this site produced excessive excavation costs for the gallery
installation, and it was deleted from further consideration.
Penstocks
In all cases, penstock routes would closely parallel the creek, taking
advantage of the topography to maintain moderate slopes in the upper reaches.
Penstock lengths would be approximately 7,150 feet, 5,900 feet, and 1,640 feet
for sites 1, 2, and 3 respectively. A short portion (approximately 200 feet) of
the penstock for site 2 would require significant side-hill benching, and
probably rock-bolting; the remainder of that route as well as the other sites
could take advantage of natural benches on moderate side slopes. The site 2
penstock would also require the greatest amount of new access construction.
This penstock would intersect the existing trail approximately 1,200 feet
downstream from the damsite.
High density polyethylene pipe is considerably cheaper than steel pipe,
but does not exhibit the same strength characteristics. Polyethylene pipe with
-11 -
-12-
FIGURE 4
FACILITIES LAYOUT
BEAR CREEK
HYDROPOWF~ PROJECT
~00 I 0
MANHOLE INTAKE RIPRAP
PROFILE
GABIONS . . . i:, ·
3' x IO'x 12' (TYP.} y
A./OT£:
O'V.t!ft? A".:: c:. .P'//"9'~
..:5/ .::J/\/4 V -4 .RJ/
BET~ecA/ .:'r.rTE:S~ PERSPECTIVE VIEW
(RIPRAP NOT SHOWN)
-13-
FIGURE !5
DIVERSION AND INTAKE
(TYPICAL)
BEAR CREEK
HYDROPOWER PR OJ EC T
N. T. S.
A •
PLAN VIEW
~/' J/£,A:/T t?~A'VE.C. /AIF/£:7"~/P...V ,
' 'A'T.e-v.A'..:.r.e cv#.t:.~ER.Y 1
. LJ'A'I'~.</E;('
R</EL.tt. $C ...eE.a/
P//i!£; 6 tP /.1?}'
/S"'.5T.C. C~.!!"C/c:::'..f'
P/...OE
GALLERY SECTION A-A
FIGURE 6
ALTERNATIVE DIVERSION
a
INTAKE
DAMSITE SECTION 8-8 HYDROPOWER PROJECT
N.T.S.
-H-
inside diameters of 32" and 12" can withstand 80 and 160 pounds per square
inch (psi), respectively, whereas the same sized 1/4" steel pipe can withstand
about 225 and 600 psi, respectively. Polyethylene pipe could be used for the
damsite 3 option and would be 40 to 50 percent cheaper than comparable steel
pipe. Pipe pressures for the upper damsite options require the use of steel
pipe. Partial use of polyethylene pipe (in the upper reaches where pressures
are low) was considered, but savings amounted to only about 5% of total
penstock costs.
Powerhouse Layout
The powerhouse would be a conventional indoor plant with the
substructure constructed of reinforced concrete and the aboveground housing
being a pre-engineered 40' x 30' x 20' metal building. Natural foundation
materials at the site are sand, gravel, and cobbles. The powerhouse would
contain the turbine, generating unit, controls, governors, and switchgear.
Control facilities would be for an unmanned plant, and protective devices
would operate automatically to protect the equipment.
Generation Facilities
Generation would be by Pelton-type turbines, driving single phase (10),
60 Hz, 480 V, 0.8 power factor synchronous generators. Drip proof housing
would be provided. The generator would be open ventilated with an 80°C rise,
Class B insulation and no provisions for overload. The generator would have
full runaway speed capability. Excitation systems would be in accordance with
manufacturer's standards.
Power Transformer. One 480 V/14.4 kVA 10 transformer, OA class with
minimum non-premium impedance would be provided. All necessary
terminations, switchgear, and protective devices would also be provided.
Load Controller. The size of the jets and thus the power output of the
turbines would be controlled by a needle in the center of the needle nozzles
and needle tips. The movement of the needle would be controlled by the
governor. A jet deflector would be located just outside the nozzle tlp to
deflect the jet from the buckets to effect sudden load reductions.
Generator Voltage System. The connection between the generators and
breakers would be with cable. The generator and station service breakers
would be metal enclosed drawout type rated 600 V, with 1600 amp frames.
The breakers would be combined in a common switchgear lineup along with
generator surge protection and instrument transformers.
Unit Control and Protective Equipment. Unit controls would consist of manual
startup and shutdown circuits, basic protective relays, and basic
instrumentation. Protective relays for each unit would include generator
differential, overspeed, overvoltage, and ground overcurrent. Instrumentation
for each unit would include a voltmeter, an ammeter, a wattmeter, and a
watthour meter. The controls would be contained in a single cabinet. No
annunciation or station battery would be provided.
-15-
Station Service. The station service power would be obtained via a tap
between the generator breaker and the main power transformer. The station
service distribution panel would be adjacent to the generator switchgear
lineup. Station service power distribution would be at 480 volts, single phase
transformed to 120 volts single phase power. Standby diesel generation
(approximately 25 kW) sufficient to supply station power needs would be
provided.
Access
From the Hope Highway to the powerhouse site, the project area is
accessible by a one-mile gravel service road that would require only minor up-
grading. For approximately 1/2-mile above this area, the access consists
essentially of a 12-foot travel surface, except in a short reach where placer
operations have encroached. The remainder of the existing access is an
overgrown trail of between 3 and 6 feet in travel width. Grade on most of this
trail is approximately 10%, with three short locations with grades between
' ')-'6 and 25%. No blasting is anticipated along the final access route.
li1 all cases the access road and penstock route would be combined, with
the penstock being protected as much as possible under the toe of the cutbank.
This would preclude the need for clearing and grading two separate rights-of-
way, and also provide an additional measure of protection for the penstock
without restoring to full burial.
Four major avalanche chutes are present within the project area.
Progressing upstream, they are located as follows. The first is just
downstream of site 3. It would probably not have a significant impact on a
site 3 penstock, but would effect both sites 1 and 2. The second is between
sites 2 and 3, and is just up-slope from the point at which the existing cat trail
crosses the stream. It is at this point that a new access route would need to
diverge from the cat trail and follow another, older existing trail further
uphill. The third chute is located between sites 2 and 3. This chute is
extremely large and goes all the way across the stream. It would have
significant impact on the penstock routes for sites 1 and 2. The fourth chute,
which is also quite large, is just upstream from site 2, and would impact the
site 1 penstock.
TRANSMISSION
Hope currently receives power from Chugach Electric Association
(CEA) via a 14.4 kV single phase (10), 2 wire (2W) distribution line which
originates at the three phase (30) transmission line from Anchorage. The single
phase substation is 21 miles from the proposed Bear Creek powerhouse site.
CEA does not anticipate a need for 30 power in Hope.
Electricity is normally generated and transmitted as three phase power;
however, single phase systems are the rule for supplying electricity to
residences and other small consumers. If power was generated at Bear Creek
by a conventional three phase generator, single phase power could be delivered
to the Hope customers (and excess back-fed into the CEA grid) by one of two
methods:
-16-
Option 1 -Transmit all power produced at Bear Creek as 30. This
would require construction of 1 mile of all new 30 line and the upgrading of 20
miles of existing 10 line to 30. The 10 transformer at the existing
10 substation would have to be replaced with a 30 transformer. Switching
gear would also be provided. The cost of this option would be about
~4,750,000.
Option 2 -Dead-end two phases at Bear Creak and tie the remaining
phase into the existing 10 line. This option would only cost about S 17 5,000,
since only one mile of new 10 line and switching gear would be required.
However, dead-ending two phases would result in the loss of about 4296 of the
total power produced and associated project benefits. It would also cause an
imbalance in the 30 system which could ultimately lead to mechanical failure.
Provisions for dummy loads would reduce the potential for failure.
An additional option is available and would eliminate both the high
transmission cost and excessive power losses.
Option 3 -Generate power at Bear Creek with a 10 generator. Single
phase generators with ratings higher than 50 kVA are not readily available but
could be built to specifications. The additional cost associated with using a
10 generator over a 30 generator becomes more pronounced as plant size
increases but would not significantly affect total project costs. The additional
expense is also justified when considering that it would displace extremely
high transmission line costs, as well as provide maximum project benefits.
Transmission line costs associated with this option would be about the same as
for option 2, $17 5,000. This option is the most economical and therefore
assumed in subsequent analyses.
Two alternatives for the distribution of power produced at Bear Creek
were investigated. The first assumed that the power would be fed into the
existing CEA grid system, and the second assumed that only the communities
along the Hope Feeder Line would utilize the power. The first alternative
would allow all energy produced at Bear Creek to be marketable. Marketable
energy for the second alternative would be the lesser of energy produced and
energy simultaneously demanded. Benefits associated with the second
alternative would therefore be significantly lower than those associated with
the first. Costs would be about the same; switching gear would vary slightly.
lt is obvious that the first alternative yields the greatest net benefits, and the
second is therefore excluded from further consideration.
Transmission voltage for the new 1 f/J line would be 14.4 kV 1 f/J 2W. Fuse-
type disconnects would be provided on all three sides of the intertie point.
-17 -
ENERGY ANALYSIS AND PLANT SELECTION
Energy Potential of Bear Creek
For each of the three dam sites considered, a wide range of installed
capacities was evaluated. The program HYDUR was used to estimate the
average annual output for each plant, based on physical constraints of the
assumed turbine and the flow characteristics of Bear Creek. Table 2
summarizes the project features and energy potential associated with each
dam site.
TABLE 2
Summary of Damsite Options
Installed Penstock Gross Avg. Annual
Damsite Capacity Length Diameter Head Output
No. (kW) (ft.) (in.) (ft.) (MWh)
200 12 1,317
to 7,150 to 700 to
1,000 26 2,296
2 200 14 1,271
to 5,900 to 580 to
1,000 28 2,034
3 75 14 519
to 1,640 to 210 to
500 32 720
-18-
Selected Damsi te
The National Economic Development (NED) Plan provides the basis for
evaluating the options available. Benefits and costs were developed for each
of the damsites and corresponding plant sizes, as outlined in the section on
Economics. That plant which shows maximum net benefits would be the
selected, or optimum, plant. Even though the upper two damsites have the
potential to provide about twice as much power as does the lower site, net
benefits were consistently higher for the lower site options; all were negative.
Maximum net benefits for damsite 1 were -$233,000 (200 kW plant), -$213,000
for damsite 2 (also the 200 kW plant), and -$97,000 for damsite 3 (150 kW
plant). Damsite 3 is therefore the optimum site. Figure 7 shows the
evaluation graphically.
0 1---------~--------L---------L-------~--------_J
/5ELECTEL7}
,;
-300
FIGURE 7 I NET BENEFITS
-19-
Selected Plan
Of the plant sizes considered at damsite 3, the 150 kW option provided
maximum net benefits and is therefore the selected plan. Detailed benefit and
cost analyses are given in the Economics Section to show how the maximum
net benefits were derived. Below, in table 3, are the turbine configurations
and penstock sizes for each option, as well as the resulting average annual
output.
Installed Capacity
(kW)
500
200
150
125
100
75
TABLE 3
Summary of Project Features (Damsite 3)
Turbine Sizes
(kW)
200,300
75,125
50,100
50,75
2@50
25,50
Penstock Diam.
(in.)
32
22
18
18
16
14
Avg. Annual
Output (MWh)
720
846
767
691
619
519
Figure 8 shows the temporal distributions of the energy potential of the
creek at damsite 3 and the energy demand at Hope (assuming moderate growth
and near-term historic monthly breakdowns). It is readily noted that times of
peak demand do not coincide with times of peak flow (and peak power
production). This emphasizes the desirability of tying the proposed
hydropower plant into the existing CEA grid.
/A/5T.A' L<t!:.t:L? C....4 P~/ r ....Y
(.ii> e~ / (11:' ..?~ K .A/
FIGURE 8, ENERGY DEMAND YS .. ENERIY POTENTIAL, OAMSITE 3
-20-
ECONOMICS
Benefit Analysis
Benefits for the Bear Creek project were developed based on the
potential energy savings that would be realized from the most likely
alternative electrical generating method. Only the fuel portion of CEA
production costs can be avoided with construction of the project, since it
would not eliminate any existing or future electrical generating capacity.
Energy purchased from CEA is currently produced by natural gas turbines.
The natural gas currently costs CEA a weighted average of $1.23 per million
BTU (mBTU). In 1997 current gas purchase contracts will expire and gas costs
are assumed to increase to the world price of $3.36/mBTU. The average
annual equivalent gas price for 1990 (the assumed power-on-line date for the
Bear Creek project), based on a combination of existing contract prices and
current world prices, would be $2.55/mBTU, which is equivalent to
S0.032/kWh.
Data Resources, lnc. has ascertained that the cost of natural gas (as well
as other fueb) rn1y be .::1ssumed to increase over time at a significantly higher
rate than other costs would (labor, machinery, materials, etc.). This net
increase in future fuel prices represents an additional cost which can be
avoided by hydropower development and is therefore claimed as a project
benefit. The relative rates of increase of natural gas costs determined by
Data Resources, Inc. are as follows:
Period Rate
1983-1985 3.69%
1986-1990 3.69
1991-1995 4.99
1996-2000 2.68
2001-2014 1.72
2015, on 0
These annual growth rates were applied undiscounted from the present to
1990 (POL date) and then discounted annually at 8 3/8% to the end of a 50
year project life (2040). The fuel escalation factor resulting from this future
growth is 1.85 (i.e. 1.85 x avg. avoided fuel cost = total avoided cost), which
means that the fuel escalation benefit alone is 0.85 times the average avoided
fuel cost, or S.027 /kWh.
All energy produced at Bear Creek would be usable since that in excess
of the demand in the immediate Hope vicinity would go into the CEA grid
system for distribution to other users. The average annual output was
therefore credited with the full gas cost benefit and fuel escalation benefit
(S0.059/kWh, total).
-21-
Other benefits were considered but not found applicable. There would be
no dependable capacity benefit since winter flows are extremely low. Benefits
for displaced diesel costs associated with power outages on the CEA
distribution line would not be significant since the frequency of outages and
time down are minimal. In addition, outages occur mainly during the winter
when the power potential of Bear Creek is not sufficient to meet the demand
in Hope. No employment benefits were claimed since Hope does not qualify as
an area of high and persistent unemployment.
Benefits for the plants at damsite 3 are summarized below, since that
site was found to be the optimum (see Energy Analysis). Benefits shown are
l OOO's of dollars.
Installed Capacity (kW) 500 200 150 125 100 75
Avg. Annual Output (MWh) 720 846 767 691 619 519
Displaced Gas Cost Benefit 23 27 24 22 19 17
($.032/kWh) ($1,000)
Fuel Escalation Benefit 19 23 20 19 16 14
($.027/kWh) ($1,000)
Total Annual Benefits ($1,000) 42 50 44 41 35 31
Cost Analysis
Costs were derived for each of the project sizes based on October 1984 prices,
and included the following items: damsite development (mobilization,
demobilization, gabion diversion, manhole-type intake, road improvements, land
acquisition), penstock (steel for upper sites, high density polyethylene for lower
site), powerhouse, transmission, contingencies (20%), engineering and design (7 .5%),
supervision and administration (6.5%), and interest during construction (18 months
at & 3/&%). Costs were amortized over 50 years at & 3/&%. An additional &% of
the annual investment costs was included to account for operation and
maintenance. As with the benefits, a breakdown for plants at the lowest damsite,
site 3, is given since that site was found to l:?e the optimum.
-22-
Costs shown are 1OOO's of dollars.
Installed Capacity (kW) 500 200 150 125 100 75
Site Development
Mob and Demob 60 (typ)
Diversion 9.5 (typ)
Intake 8 (typ)
Road Improvements 156 (typ)
Land Acquisition 2 (typ)
Penstock· 403 264 212 212 195 164
Powerhouse 490 465 460 460 455 450
Transmission 175 (typ)
------
Subtotal 1,304 1' 140 1,082 1,082 l ,060 l ,024
Contingencies 261 228 216 216 212 205
Engr. & Design 98 86 81 81 80 77
Supv. & Admin. 85 74 70 70 69 66 -..........-
T ota1 First Cost 1,748 1,528 1,449 1,449 1,421 1,372
IDC 108 94 89 89 88 84
Total lnv. Cost 1,856 1,622 1,538 1,538 1,509 1,456
Amortized Cost 158 138 131 131 129 124
OM & R 13 11 10 10 10 10
T ota1 Annual Cost 171 149 141 141 139 134
-23-
DETAILED COST ESTIMATE (150 kW option)
ITEM/DESCRIPTION QUANTITY UNIT UNIT PRICE TOTAL
MOB & DEMOB 1 LS $60,000 $60,000
DIVERSION & INTAKE
Rock Excavation 15 CY 100 $1,500
Mat Gabions
(3'xl0'x12') 4 EA 1,250 5,000
Riprap 30 CY 100 3,000
Precast Concrete
Manhole 1 EA 5,000 5,000
Trashrack 1 EA 3,000 3,000
Total Diversion & Intake $17,500
ROAD IMPROVEMENTS
Upgrade Existing
Road 5,400 LF 13.70 $74,000
Construct New
Road 1,640 LF 50 82,000
Total Road Improvements $156,000
LAND ACQUISITION
Special Use Permit Fee 8 AC 250 $2,000
PENSTOCK
1 gu (I.D.) Poly-
ethylene Pipe 1,640 LF $129 $212,000
POWERHOUSE
Structure 1 LS $140,000 $140,000
Turbines/Generator 1 LS 146,000 146,000
Accessory Electric 1 LS 143,000 143,000
Aux. Systems & Equip 1 LS 11,000 11,000
Switch yard 1 LS 20,000 20,000
T ota1 Powerhouse $460,000
-24-
TRANSMISSION LINE
New !-phase Trans.
Line
Transfer Switching
Station
Total Transmission Line
SUBTOTAL
Contingencies (20%)
Engineering & Design (7 .5%)
1
1
Supervision & Administration (6.5%)
TOTAL FIRST COST
Interest During Construction
TOTAL INVESTMENT COST
Mile 125,000 $125,000
LS 50,000 50,000
$175,000
$1,082,000
216,000
81,000
70,000
$1,449,000
89,000
$1,538,000
-25-
Evaluation
Net benefits and benefit-cost ratios for damsite 3 are summarized
below:
Installed Annual Annual Net
Capacity Costs Benefits Benefits B/C Ratio
500 kW $171,000 $42,000 -$129,000 0.25
200 149,000 50,000 -99,000 0.34
150 141,000 44,000 -97,000 0.31
125 141,000 41,000 -100,000 0.29
100 139,000 35,000 -104,000 0.25
75 134,000 31,000 -103,000 0.23
CONCLUSIONS AND RECOMMENDATIONS
A hydropower project on Bear Creek could not meet the full energy
demand for the CEA Hope Feeder Line, due to low winter flows. Tying the
proposed plant into the existing CEA grid is much more economical than using
the hydro power for the communities along the Hope Feeder Line only. Of
the three damsites considered, the lower one was optimum, due to
considerably higher penstock and road improvement costs for the two upper
s1tes. The optimum plant size was 150 kW. None of the numerous options
investigated show positive net benefits.
No further Corps of Engineers studies of hydropower development at
Bear Creek are warranted at this time.
-26-