HomeMy WebLinkAboutCordova Reconnaissance Study 1979ALASKA POWER AUTHORITY
Ll BRARY COPY
DO NOT REMOVE FROM OFFICE
RECONNAISSANCE STUDY
OF
HYDROPOWER SITES
NEAR
CORDOVA, ALASKA
for
Department of the Army
Alaska District, Corps of Engineers
P. 0. Box 7 002
Anchorage, Alaska 99510
by
CH2M HILL Engineering of Alaska, Inc.
310 K Street, Suite 602
Anchorage, Alaska 99501
Contract No. DACW85-79-J-0019
Kl2927.CO
l11
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•
• ..
•• •• SUMMARY
This reconnaissance study was conducted to determine if
hydropower development can replace all or portions of the
diesel-generated power for the city of Cordova and the
surrounding area.
Cordova is located on the south-central coast of Alaska,
approximately 160 miles southeast of Anchorage. The city is
situated on Orca Inlet near the eastern entrance to Prince
William Sound, east from Hawkins Island. The extent of the
settlement is confined by Mt. Eyak to the north, the abrupt
foothills of the Heney Range to the south, Eyak Lake to the
east, and Orca Inlet to the west. Most of the city's develop-
ment occurs on a low divide between the waters of Orca Inlet
and Eyak Lake, on the foothills of Mt. Eyak, and along both
the north and south shores of Eyak Lake. Fishing and fish
processing have continued to be the primary economic activities
in the city.
All small hydropower sites identified in the scope of work
have been studied without the aid of actual site visits,
which were prevented by poor weather conditions and time
constraints. In addition to a study of these small hydro-
power sites, an analysis and review was carried out on
previously studied alternatives on Power Creek prepared by
A&L Engineering, Harstad-Galliett, and Marks Engineering.
Energy requirements were projected for the city of Cordova
for the period from 1979 to 2030. The present worth of the
diesel generation to meet these requirements was calculated
by assuming that diesel fuel would escalate 0 percent, 2
percent, and 5 percent faster than the general inflation
rate.
Reconnaissance-level cost estimates were prepared for seven
potential small hydropower sites by use of cost curves and
other criteria, as shown in appendix B. All development
concepts with the exception of Crater Lake were considered
as run-of-the-river type projects. The cost for previously
studied small hydropower sites on Power Creek was updated to
October 1979 prices. Of the four alternatives proposed for
Power Creek, two were run-of-the-river type and two were
storage development concepts.
A comparison was made between the present worth of both the
small hydropower sites and Power Creek alternatives and the
present worth of the community's diesel needs for the next
50 years. Because of the large present worth of diesel
generation to meet the community's future requirements and
relative small present worth of hydropower, all sites passed
iii
the first screening effort. The next step was to compare
the present worth of hydropower sites to the amounts of
diesel that they would be expected to replace, again using a
50-year time frame and diesel fuel escalation costs of
0 percent, 2 percent, and 5 percent. This analysis revealed
that only two small hydropower sites out of seven were
feasible. All three alternatives proposed for Power Creek
appeared to be feasible.
The conclusions of this reconnaissance-level investigation
are that ~orne hydropower develQpJ!l~Il._!: _j.n __ t}l~_ immediate area
of Cordova lS a feasible alterrr~tive to diesel generation.
Because of the size of the watersheds and hydrologlc cycles,
which are typical of south-central Alaska, other types of
power, such as diesel generation, would have to be used to
take care of the remainder of the community's needs.
On the basis of the screening process developed in chapter 5,
it is recommended that a detailed feasibil~study, with
the benefit of a site visit, be made on the small hydropower
sites on Humpback Creek and Crater Lake.
The most desirable alternative on Power Creek, in light of
geotechnical obstacles and other unknowns related to con-
trolling seepage in earth filled dams, is the proposed 5-MW
run-of-the-river power plant at mile 3.2 with provisions for
staged development.
It is recommended that additional geotechnic_~l_, __ _h_yQ_~ologis:_L
q.ng_ environme-ntal stud-ies,-rncTUOin~a--mo-re _prec~f>_~ _cost
estimate, be carried-out-onthemost de-sirable Power creek deve_!opment conc~p·c-------------d----------------------------------
Concurrently, a storage development concept upstream from
mile 3. 2 should be investlgatea--to--produce additiorfal generation
nexibij'ity. -----------
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CONTENTS
1.
2.
3.
4.
5.
Summary
Introduction
Power Needs for Cordova
Existing Power Requirements and
Generating Facilities
Review of Economic Conditions and
Population Growth
Future Energy Requirements
Present Worth of Diesel Generation
Assessment of Small Hydropower Sites
Field Methods
Hydrology
Environmental Concerns
Development Concept
Community Hydropower Sites
Power Creek Evaluation
Previous Studies
Power Demands
Potential Hydropower Generation
Feasibility Evaluation
Conclusions
Comparison of Community Power Needs
and Hydropower Potential
iii
1
5
5
6
9
10
13
13
13
14
15
17
23
23
26
26
28
28
33
Small Hydropower Site Screening Process 33
Power Creek Sites Screening Process 37
Bibliography 41
Appendixes
A
B
c
Physical Setting and History of Cordova
Cost Estimates
Operation and Maintenance Costs
for Diesel Generation
v
A-1
B-1
C-1
TABLES
1.
2
3.
4.
5.
6.
7.
8.
9.
Small Hydropower Sites Near Cordova
Peak Demand and Annual Energy Projections
for Cordova
Present Worth of 50 Years of Diesel Generation
at Cordova
Small Hydropower Site Summary
Power Creek Sites Summary
Power Creek Project Demands and Potential
Generation
Present-Worth Comparison of Small Hydropower
Sites and Diesel-Generating Alternative
Present-Worth Comparison of Power Creek Hydro-
power Sites and Community's Total Diesel Needs
Present-Worth Comparison of Power Creek Hydro-
power Sites and Diesel-Generation Alternative
FIGURES
1.
2.
3.
4.
Map of Cordova Area
Humpback Creek and Crater Lake Sites
Heney Creek, Hartney Creek, and Unnamed
Falls Hydropower Sites
Power Creek Hydropower Sites
vii
3
10
11
18
25
27
36
39
39
2
19
21
33
•• Chapter 1
•• INTRODUCTION
This report presents an evaluation of six drainage basins
with potential hydropower sites in the Cordova, Alaska,
area. The intent of the study was to identify the current
and expected future power needs of the Cordova area and to
evaluate potential hydropower sites. The evaluation was
based on the ability of each site to meet the community's
needs or at least to displace a portion of the increasingly
more costly diesel fuel that is currently used for generation.
The study covered the immediate Cordova area, as shown in
figure 1. Because of the mountainous terrain and the high
levels of precipitation and runoff, the region surrounding
Cordova has a high hydropower development potential. The
population of the region is small and the distance to most
hydropower sites is great. Large hydropower projects are
not feasible, since the cost of transmission interties to
nearby communities--such as Valdez, for example, 55 miles to
the north--is prohibitive. Cordova and other communities on
Prince William Sound have developed their own means of
generating electricity.
Two groups of hydropower sites were studied. The first
group includes seven sites in five separate drainage basins
that were selected for reconnaissance-level investigations.
All seven sites were identified in the scope of the study.
No attempt to look for other nearby sites was made because
that preliminary screening was accomplished by the Corps of
Engineers, Alaska District. The intent of these reconnais-
sance-level investigations is to identify which of the seven
sites show enough promise to warrant more detailed feasibility
studies.
The second group of hydropower sites studied includes those
on Power Creek which were the subject of previous engineering
reports. These reports were written between 1949 and 1977
and reflect various alternatives in different reaches of
Power Creek. The intent of this study is to update the cost
estimates contained in these reports to 1979 levels and to
compare the feasibility of each development concept. Approx-
imate site distances to the city of Cordova are shown in
table 1.
1
GULF OF ALASKA
5 r==
Scale in
10
==y
Miles
15 20
I
••
.. ,
FIGURE 1
MAP OF CORDOVA AREA
2
Table 1. SMALL HYDROPOWER SITES NEAR CORDOVA
Number of
Sites
1
2
2
1
1
3
Drainage Basins
Humpback Creek
Heney Creek
Hartney Creek
Crater Lake
Unnamed Fa 11 s
Power Creek
Distance from
Cordova
6 miles northwest
1-3/4 miles south
3 miles southwest
2-3/4 miles northeast
7 miles southwest
8 miles northeast
Detailed information on Cordova, its electric utility, and
its power needs is presented in chapter 2. Chapter 3 contains
information on the proposed small hydroelectric sites that
were studied at the reconnaissance level. Chapter 4 contains
the review and analysis of the Power Creek hydropower sites.
Chapter 5 is a comparison of the power needs and hydropower
resources available from the small hydropower sites and
Power Creek. Appendix A covers the physical setting of
Cordova and gives a brief history of the area; appendix B
presents cost data; and appendix C contains operation and
maintenance costs for diesel generation.
3
•• Chapter 2
•• POWER NEEDS FOR CORDOVA
This chapter presents the existing power requirements and
generating facilities, the economic base that stimulates
population growth in the Cordova area, and the anticipated
energy requirements projected to the year 2030. The present
worth of meeting those energy requirements with diesel
generation is also given.
EXISTING POWER REQUIREMENTS AND GENERATING FACILITIES
The Cordova Electric Cooperative, Inc. (CEC~ supplies its
customers in the city of Cordova and the surrounding area
with electrical power through diesel generation. A review
of 1978 records revealed a total generation of 15,307,000 kWh
and a peak demand of 3,150 kW. The peak demand has histor-
ically occurred in the summer months (July, August, and
September) and relates to fish-processing activities in the
area.
While there has been a trend for annual energy distribution
to become more uniform, the summer peaking characteristic of
this maritime community with fish-processing activities will
probably prevail through the next few years. Power consump-
tions and customer classifications are recorded in the
annual REA Form 7 (Financial and Statistical Report).
Pertinent data from the 1978 tabulation are summarized as
follows:
1978 Average Number of Customers by Class:
Rural residential
Town residential
Small commercial (50 kVA or less)
Large commercial (over 50 kVA)
Total 1978 CEC generation *
Peak 15-minute summer demand, August *
Peak 15-minute winter demand, January
*
150
535
235
8
15,307,000 kWh
3,050 kW
3,150 kW
Trend in peaking has been as follows:
Winter peaks are larger than preceding summer peaks.
Summer peaks are larger than preceding winter peaks.
Annual community load factor 55%
The power needs are met through an existing generating plant
made up of the following units:
5
One 600 kW
Two 750 kW
One 1,100 kW
One 1,950 kW
One 2,650 kW
One 2,500 kW
10,300 kW nameplate total
Under normal conditions, a diesel plant's firm capacity
would be regarded as the nameplate capacity less the largest
single unit. However due to the poor condition of some of
the units, the firm plant capacity is estimated by CEC to be
approximately only 5,000 kW.
Power is distributed from the powerhouse through a 2,400-volt,
3-phase feeder to a 5-MVA 2.4/12.5-kV substation and switchyard.
The distribution circuits from the switchyard include one
2,400-volt and three 7 ,200/12,740-volt lines. Modifications
of the substation are underway to add an additional 5-MVA
transformer to the substation and upgrade the existing
2.4-kV feeder to 12.5 kV.
REVIEW OF ECONOMIC CONDITIONS AND POPULATION GROWTH
Economy
Economic information for this study was obtained from the
Cordova Comprehensive Development Plan (1976) and the review
draft of the Cordova Coastal Management Program (1979),
which is subject to change.
The major contributors to Cordova's current economy are the
'fishing and fish-processing industry and the U.S. Coast
Guard. These and other contributors to the city's economic
base are briefly discussed below.
Fishing and Fish Processing. Cordova is the center of
fishing and fish-processing operations for Prince William
Sound. The industry provides approximately one-half of the
average annual full-time employment in Cordova. Local
commercial catches include all five species of salmon,
shrimp, herring, herring roe, halibut, razor clams, and
king, Dungeness, and tanner crabs. The tanner (snow) crab
fishery has been developed in the last 10 years. The fishery
operates in the winter, thereby providing more year-round
employment in a predominantly seasonal industry.
The fishing and fish-processing industry is expected to
experience steady growth in the future. The number of
persons employed in the industry is projected to increase
from the 1975 figure of approximatey 410 to 750 by 1990.
6
The fish-processing activity is expected to grow more than
fish harvesting.
Any major growth in the industry presently depends on success-
ful rehabilitation of salmon runs in Prince William Sound by
the Alaska Department of Fish and Game and the development
of bottomfishing. Cordova is not expected to play a major
role in future bottomfish development in Alaska.
Oil and Gas Development. The northern Gulf of Alaska has
long been considered by major oil companies as one of the
most promising areas in the state for oil and gas develop-
ment on the Outer Continental Shelf. The state has held six
competitive offshore lease sales in the area since 1960. No
oil has been discovered, and the last oil company exploratory
platform was removed from the northern Gulf of Alaska in
late 1978.
Exploratory activities are expected to shift to the western
Gulf of Alaska. If, however, exploratory activity resumes
and is successful in the Middleton Island area, Cordova
would serve as a primary support center for development.
The city would serve only in a secondary support capacity
for oil or gas development in the area between Cape Suckling
and Icy Bay. Yakutat would be the primary support center
for this area.
Mining. Although mining, especially of copper, played a
major role in the development of Cordova in the early 1900's,
it is not expected to play an economic role in the future.
Most of the copper produced in the state came from the
Kennecott mines in the Chitina River valley north of Cordova
between 1911 and 1938. (See appendix A.) These deposits
are now believed to be largely depleted.
Gold and silver are known to exist in the Cordova area, but
deposits do not appear extensive enough to warrant investment
in their extraction. Coal deposits also exist but are
uneconomical to mine because of the complexity of the geologic
formations in which they lie.
Mining activities in the Cordova area are suspended at least
temporarily until the Alaska D-2 land issues are settled.
If these issues are not taken into consideration, new mineral
exploration and mining would be inhibited by the lack of a
transportation link to the potentially rich areas northeast
of Cordova.
Timber Harvesting and Processing. The timber industry has
never played a major role in the economy of Cordova. Final
settlement of the D-2 land issues and the subsequent implica-
tions for timber harvesting from the Chugach National Forest
7
are therefore not expected to have a major impact on Cordova's
economy.
The Eyak Native Village Corporation is interested in timber
harvesting and establishing a mill on lands recently conveyed
to it under the Native Claims Settlement Act. This develop-
ment is projected for the mid-1980's, and is expected to
employ approximately 50 persons by 1990.
Government. The U.S. Coast Guard maintains a search-and-
rescue operation and provides navigational aid out of Cordova
for the area between Seward and Yakutat. The Coast Guard
has announced plans to expand its operations with the con-
struction of a helicopter air station. If the station is
constructed, Coast Guard employment is expected to increase
from its 1975 level of approximately 80 persons to about 130
by 1990.
Tourism and Recreation. Completion of the Copper River
Highway and improved Alaska State Ferry System service
combined with improved tourist attractions and accommoda-
tions in Cordova will enhance tourism. Local promotion is
also important to development of the tourist industry.
Substantial improvements in both air and ferry service to
Cordova are expected over the next decade.
Services and Trade. The services and trade sector of the
economy includes support activities such as wholesale and
retail trade, banking and insurance, real estate, and personal
and business services. This sector of Cordova's economy is
expected to experience substantial growth in the future and
is projected to employ approximately 630 persons by 1990.
Population Growth
Recent Trends. Cordova's population remained relatively
static from the early 1900's to 1960. The population in
1960 was 1,176, only 2 percent above the 1910 census figure
of 1,152. Since 1960, however, the city has experienced an
accelerated rate of population growth, largely because of
the following reasons:
The city undertook major dock and boat harbor improvements
as a result of damage to those facilities by the 1964 earth-
quake. Dredge spoils from these activities were used to
create a 20-acre industrial park adjacent to the city dock.
Much of this park has been developed for seafood-processing
activities.
Also, the development of the tanner (snow) crab fishery,
which operates in the winter, has resulted in an extended
fish-processing season and greater year-round employment.
8
Reducing the seasonality of this crab industry has allowed
more workers to make Cordova their full-time place of residence.
Projections. The city of Cordova is expected to continue to
experience steady increases in population. Projections for
the city for the next 10 years indicate an estimated 2,800
persons in 1980, 3,400 by 1985, and 4,000 by 1990. The
projections reflect the "most probable" growth scenario
described in the review draft of the Cordova Coastal Manage-
ment Program.
FUTURE ENERGY REQUIREMENTS
Future power requirements and associated costs have been
projected by Marks Engineering in their study entitled
"Power Cost Study, 1978-1992" (July 1977). Recommendations
from the study, quoted directly, are as follows:
I. CPU* should purchase and install a refurbished and
warranted 2,650-kW diesel generator as soon as
practicable with REA financing 60% of the estimated
cost of $1,000,000 at 2% interest and CPU financing
40% with revenue bonds.
*During this study, the Cordova Electric Cooperative
(CEC) was part of the Cordova Public Utilities
(CPU).
II. CPU should initiate immediate steps to develop a
5,000-kW hydroelectric plant at Power Creek by
1982.
Item I of the recommendations has already been implemented
'with the installation of a 2.6-MW electromotive diesel unit
producing a system efficiency of 13 kWh per gallon. No
further evaluations have been carried out since the publica-
tion of the 1977 report with the exception of a limited in-
house study by the Cordova Electric Cooperative to update
the consultant's findings.
A comparison of REA Form 7 (Financial and Statistical Report)
for 1978 and the previous 2 years' figures revealed a load
growth rate in Cordova of about 8 percent per annum. Esti-
mated projections by the CEC over the next 4 years would be
in the neighborhood of 10 percent, attributed to the expansion
of fish-processing facilities and residential development in
the Whitshed area. On a long-term basis, however, it is
anticipated that an annual growth rate of 5 percent, as
experienced in the 1960's and 1970's for Alaskan communities,
will prevail. From the expected 5-percent long-term growth
rate and a projected annual load factor of 55 percent, the
peak demands and annual energy requirements have been provided
9
to the year 2030. These projections are summarized in
table 2.
Table 2. PEAK DEMAND AND ANNUAL ENERGY PROJECTIONS FOR CORDOVA
Year
197 8 (record)
197 9
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
2000
2010
2020
2030
MW
Peak Demand
3.2
3.3
3.5
3.7
3.9
4.1
4.3
4.5
4.7
4.9
5.2
5.4
5.7
9.3
15.2
24.7
40.0
PRESENT WORTH OF DIESEL GENERATION
Million kWh
Annual Energy
15.3
16.1
16.9
17.7
18.6
19.5
20.5
21.5
22.6
23.7
24.9
26.2
27.5
44.8
7 2. 9
118 .8
192.7
Fuel cost in Cordova during peak demand in August 1979 is
reported by CEC at $0.71 per gallon, which yields a fuel
cost of 5.5¢ per kWh. The present worth of continuing
'diesel generation for the next 50 years is summarized in
table 3; the following assumptions were used in preparation
of the data:
Load growth rate at 5 perc~nt
1979 fuel cost at 5.5¢/kWh *
Capital cost ($485/kW) at*0.9¢/kWh
O&M unit cost at 1.1¢/kWh
Discount rate at 6.875
Projection period at 50 years
* As discussed in appendix C.
10
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Table 3. PRESENT WORTH OF 50 YEARS OF DIESEL GENERATION
AT CORDOVA
Present Worth of Diesel Generation
(millions of dollars)
Electric Energy
Growth Rate
5%
Escalations of:
0% 2%
41.6 60.1
The calculation of the present worth of Cordova's total
5%
124.3
diesel generation needs for the next 50 years was prescribed
in the scope of work for this study. The intent was to get
a rough estimate of the cost of continuing to use diesel
generation for that period. A feasibility-level investigation
of any specific energy alternative would normally only
consider a 20-or 30-year period, which is the general
financial life of such projects.
1 1
•• Chapter 3
•• ASSESSMENT OF SMALL HYDROPOWER SITES
Before a specific discussion of the seven hydropower sites
identified in the scope of work, a general discussion of the
methods used for this study is presented. These methods are
considered adequate for a reconnaissance-level screening of
hydropower sites.
FIELD METHODS
The project team consisted of an electrical engineer, a
civil engineer, and a representative from the U.S. Army
Corps of Engineers. The primary reason for a field visit
was to conduct on-site investigations of the hydropower
sites and to gather pertinent data through discussions with
residents, local officials, and state and federal agency
personnel. Poor weather conditions prevented the project
team from visiting the sites.
Because of the tight project schedule and the level of
effort for this study, the decision was made by the U.S.
Army Corps of Engineers to omit the field investigation.
Field reports prepared by the Corps of Engineers on two of
the sites during an earlier reconnaissance effort were
reviewed and discussed. U.S. Geological Survey 1 inch =
1 mile quad sheets were used to locate potential sites,
penstocks, powerhouse, transmission corridors, and access
roads. All other information was obtained through telephone
conversations related to power requirements, environmental
concerns, economic base, and historical data on hydropower
development.
HYDROLOGY
The maritime climate of the Cordova area is typical of the
southeastern and southern coastal areas of Alaska. This
climate is characterized by cool summers, mild winters, and
heavy and frequent precipitation throughout the year.
Frequent storms are generated in the Gulf of Alaska and move
to the Cordova area. The orographic features of the Cordova
area cause mean annual precipitation amounts to vary consider-
ably. Mean annual precipitation at the Cordova airport is
approximately 90 inches per year. Mean annual precipitation
at the city of Cordova is approximately 120 inches per year.
These two areas are only 10 miles apart.
Daily streamflows and annual runoff are influenced by such
factors as basin elevation, melt from glaciers, natural
storage of lakes along a stream, forest cover, basin orienta-
tion, and relationship to the Gulf of Alaska. On a regional
basis, mean annual runoff in the Prince William Sound area
13
is about 10 cubic feet per second per square mile. Low
flows usually occur in late winter when most precipitation
is stored as snow and the incoming radiation is minimal.
The low mean monthly runoff in this area is generally less
than 1 cubic foot per second per square mile. All of the
streams studied for small hydropower sites with the exception
of Humpback Creek and Power Creek are ungaged and required
other means to compute streamflows. A water resources atlas
was prepared by OTT Water Engineers in April 1979 for the
U.S. Forest Service, encompassing both the Tongass and
Chugach National Forests. This atlas has 21 regression
equations to calculate the following streamflow parameters:
mean annual flow, mean monthly flow; 7-day, 2-year recurrence
low flow, both summer and winter; five points on the daily
flow duration curve; and peak flow, 100-year recurrence
interval. These parameters were determined for all potential
hydropower sites and formed the basis for estimating the
potential capacity and energy at each site.
ENVIRONMENTAL CONCERNS
The feasibility of developing a small-scale project is in
many instances dependent on the environmental impacts the
project might create, the mitigative measures that could be
incorporated in the project, and the acceptability of the
project as a whole. A method of screening was developed to
evaluate certain reaches of streams. This approach allowed
a subjective evaluation of constraints to the development of
small hydropower generating plants. Primary consideration
was given to land use restrictions, wildlife considerations,
and anadromous fish concerns.
Land use restrictions included the following:
• Wild and scenic river designation
• Wilderness areas
• National or state park or monument
• National recreational area
• Wildlife refuge
• Historic and archaeological site designations
Available maps and photographs were used to evaluate the
potential sites. Fish and wildlife distribution maps prepared
in 1978 by the Alaska Department of Fish and Game were also
used. Conclusions were drawn from this background information
supplemented by discussions with federal and state officials.
Wildlife preservation also played an important part in the
selection of sites. Although the effects on wildlife will
be minimal, special attention was given to the large concen-
trations of trumpeter swans near Cordova. Clearing and
grubbing operations will be given special attention to avoid
14
destruction of existing nesting grounds and excessive distur-
bance to others. An attempt was also made to identify areas
of threatened or endangered species.
Because of the economic importance of anadromous fish species,
freshwater streams and their estuaries are fully protected
to promote natural propagation. Fish distribution maps
prepared by the Alaska Department of Fish and Game in 1978
were used to identify major and minor streams for anadromous
fish. Principal factors limiting migratory fish production,
such as impassable cascades, falls, log jams, existing dams,
and steep gradients, were identified and used in the initial
site selection process where possible. At new dam locations
where anadromous fish are present, a fish ladder and fish
screens will be included as mitigative measures. The ladder
is envisioned as being a modified aluminum steeppass, similar
to those used throughout coastal Alaska. To ensure sufficient
flow in the stream below the diversion of water through a
tunnel and/or penstock, a flow equal to twice that of the
7-day, 2-year low flow will be allowed to pass all dams at
all times. Project schedule constraints did not allow for a
preliminary evaluation by the Alaska Department of Fish and
Game. The department will only comment on site-specific
proposals. General fisheries resource information on most
of the streams and lakes investigated in this study was
provided by the Alaska Department of Fish and Game and the
u.s. Department of Agriculture, Forest Service, and Chugach
National Forest.
Access road construction could damage spawning areas and
lower fish-producing capabilities by causing siltation and
allowing the discharge of toxic substances. To minimize
,these potential impacts, an effort was made during the
reconnaissance to locate existing roads and discuss construc-
tion of new, or extension of old, roads.
The potential environmental concerns for each hydroelectric
site are summarized in table 4 of this chapter, following
the Community Hydropower Sites section.
DEVELOPMENT CONCEPT
The development concept for each site was prepared from
available data. Approximate locations of the seven sites
were identified by the Corps of Engineers in their scope of
work and verified by the study contractor.
Except for Crater Lake, only run-of-the-river hydroelectric
plants were considered. This was done to minimize the size
of stream barriers, thereby reducing the adverse environmental
impacts. Conceptual designs were sized to operate 24 hours
a day, since the capacity of each hydrosite is much less
1 5
than the community•s energy requirements. In every case,
only one turbine was considered, although multiple turbines
would improve annual energy production. Overall generation
efficiency for the turbine, generator, and transmission was
assumed to be 85 percent.
In general, hydroelectric generation occurs from May through
October. Low flows and ice problems limit generation potential
for the remainder of the year. For this study, for which
small run-of-the-river hydroelectric sites have been assumed,
there will be no winter power generation. The average
annual energy was calculated for each site from the net head
and flow capacity of each site. Fish flows, where required,
were assumed to be twice the 2-year, 7-day low flow calculated
for summer conditions (May through October). Specific
minimum fish flows were unavailable from the state fisheries
agency. The hydropower plants would be operated to provide
that minimum flow at all times.
Several available sources were used to construct reconnais-
sance-level cost estimates. The major estimating reference
was "Manual for the Determination of the Feasibility of
Adding Small Hydroelectric Power to an Existing Facility,"
now in draft form and soon to be released by the u.s. Army
Corps of Engineers. This manual is sponsored by the u.s.
Department of Energy through the Corps of Engineers Institute
for Water Research. The manual has many rule-of-thumb
existing charts, which are based on July 1978 costs. A
14 percent inflation factor was used to update these costs
to October 1979. The cost curves presented in the manual
were further escalated by a 1.6 factor to reflect Cordova
construction costs over those in the Pacific Northwest.
Careful consideration was given to "factoring" labor cost to
Alaska conditions. Equipment cost, for instance, should not
be escalated by a 1.6 factor. However, installation cost
should be greater than 1.6 because of the remoteness of all
sites. The 1.6 factor is for metropolitan areas of south-
central Alaska. The net result, with labor mobilization,
equipment shipping cost, and other factors considered, is an
increase in cost of 60 percent.
A lump-sum mobilization cost was included for each site to
cover delivery of equipment, supplies, and construction
materials to the site from Cordova. Access road construction
was estimated for each site. Where site access or construction
problems were expected to be more difficult than the norm, a
site difficulty factor was added to the total construction
cost.
Electrical distribution costs are based on recent experience
in southeast Alaska, with an incremental cost of 10 percent
16
to reflect south-central Alaska. The total cost includes
all materials and construction cost, including clearing
cost. Operation and maintenance costs were estimated for
each site. These costs were difficult to estimate because
of lack of data for extremely small hydroelectric plants.
The estimates include labor and material cost as well as
interim replacement cost. Since most of these facilities
are very small, no estimate was made for administrative
cost.
All cost estimating curves and tables are presented in
appendix B. The methods of estimating costs are consistent
with common practice for reconnaissance studies.
COMMUNITY HYDROPOWER SITES
A total of seven small hydroelectric sites to potentially
serve Cordova and the cannery at Orca were investigated.
The development concept for each site is presented in table 4.
Following this table are two blowups (figures 2 and 3) of
the u.s. Geological Survey 1 inch = 1 mile quad map, covering
potential sites north and south of Cordova. Diversion dams,
flumes, penstocks, powerhouses, access roads, and transmission
lines for each development concept are shown in the figures.
Where access roads have common alignment with flumes, pen-
stocks, and transmission lines, they are not shown.
1 7
......
00
Table 4. SMALL HYDROPOWER SITE SUMMARY
v/
Heney Creek Heney Creek Hartney Creek Hartney Creek
Latitude
Longitude
Drainage Area ( sq mi)
Mean Annual Flow
(cfs)
2-'lr, 7-Day Low Flow
(cfs)
Net Effective Head
( ft)
Full Gate Flow {cfs)
Fated Capan ty (kW)
Avg. Annual Energy
(MWh)
Dam:
Type
Size ( ft)
F'lurne:
Length ( ft)
Diameter {in.)
Penstock
Length ( ft)
Diameter (in.)
•rransmission Line:
Length (mi)
Voltage {kVo)
Cost: 6 capital ($xlg )
Annual ($x~O )
unit ($xl0 /kW)
Land ownership
EnvJ.-ronmcntal O.:mcerns
Humpback Creek
1
60° 36 I 35 11
145° 38 '25"
2.6
25
1.4
350
40
1,010
3, 296
Concrete Diversion
5x30
6,625
30
700
3~
5.9 (<-1.2)*
lS
3. 0
38.0
3. 0
The upper reaches
of the creek are
in the Chugah
National Forest;
the lower part to
the mouth runs
through Eyak
Native Land.
Creek supports pink
sdlmon to old
railroad
li t.tle sport
fishing.
(Upper) (Lower)
2l\ 28
60°31'15" 60°31'25"
145°44 '50'* 145°46 1 00"
1.4 1.8
12 15
0.6 0.9
240 100
15 18
260 130
805 419
Concrete Diversion Concrete Diversion
5x50 5x50
6,600 3, 200
18 18
1.9 1.9
5 1
2.0 1.6
11.0 10.0
7.6 12.5
Heney Creek west of the west 1/2 of
Section 33 flows through private land,
either in individual or state owner-
ship. The upper reaches of the creek
are currently within the Chugach National
Forest, although the Mt. Eccles State
selection includes the entire lenqth.
Creek supports pink and silver salmon
and some Cutthroat trout; spawninq at
mouth of creek.
NOTF.: 1\ssume Dolly Varden in all lakes and strea.rns.
;.. {+1.2) length of new underbuilts on existing poles.
'I
(Upper) (Lower)
3A ___ 3_B ____
60° 30 '15*' 60° 30 '15"
145°46'50" 145°47.5511
2.0 3. 0
l7 26
1.1 1.7
170 100
25 30
306 216
896 743
Concrete Diversion Concrete Diversion
5x50 5x50
9, 500 6, 600
24 27
4.0 4.0
15 15
3.1 2. 7
11.5 11.0
10.2 12.7
Beginning at its mouth, Hartney Creek
passes through Eyak Native lands in
controversy with the Hartney Bay
State sclectJ.on 1 then passes through
the Chugach National Forest and into
noncontToversial Eyak Native Lands.
The upper reaches and the source of
the creek lie within the Mt. Eccles
State selection.
Creek supp:,rts pink ( 2000-30iJO) ,
Chum (201)-300), and silver (200-300)
salmon in addition to cutthroat trout;
lower port1ons stream used for
spawning; active sport f~shing down-
stream of bridge.
" "'
/
Crater Lake
4
60° 34 f 15"
145°41'45"
0. 3
0. 3
1, 350
389
1,435
Concrete Diversion
5x15
4,800
18
2.3 (+1.2)*
2.0
14.7
5.0
Approxlrna tel y 1/4
of the lake (NE
quarter} belongs
to the Eyak Native
Corp. The remain-
dcr of the 1 and
and the land in
a direct north-
lies
witlnn state-
owned 1 and with-
drawn to the
City of Cordova.
Stocked with
rainbow trout;
no natural au tlet.
Unnamed Falls
5
60° 27 '20"
145 4 50 '40 ..
0.65
o. 3
440
6
190
712
Concrete Diversion
5x40
t,970
tB
9
15
2.8
10.0
14.5
'l'hi s site and its
stream (Sections
24 & 25} are Wl th-
in the Chugach
National Forest.
Creek supports small number
of pink salmon dt mouth;
also cutthroat trout.
"
I
J '
••••••••
DAM @ FLUME
PENSTOCK
TRANSMISSION LINE 0 4000 • POWERHOUSE
ACCESS ROAD Scale in Feet
19
,,
I , I .
!
?
18
---------· ·-------···--········~~--+-----\ -.,J ··,' -... I .
24
EYAK
FIGURE 2
HUMPBACK CREEK
AND CRATER LAKE
HYDROPOWER SITES
"'
. •
... ..
.. ..
r ··· .
..... ·· ....
~ \:>
.. ... ~.
, .. ·· ·· ....
...:l · ...
z -
·· ..
' ·-, . /
.-•.·
•
8
0
'it
0
II
: •II
II
.-l N
•• Chapter 4
•• POWER CREEK EVALUATION
PREVIOUS STUDIES
Power Creek has been considered for potential hydroelectric
development many times during the past 70 years. Proposed
projects have ranged from small run-of-the-river diversions
to multistage darn, reservoir, and powerplant developments.
Recent projects that have reached the serious consideration
stage include the following:
• A&L Engineering 1966 Project -50-foot-high darn at
mile 2.9 with tunnel, pipeline, and penstock to
1.8-MW powerplant which could be enlarged to
2.7 MW. Geologic studies in 1967 indicated seep-
age from reservoir could be excessive.
• Harstad-Galliett 1975 Project -140-foot-high darn
at mile 3.2 with a second stage 160-foot-high darn
at mile 6.8. Alternative of 165-foot-high darn at
mile 4.6 if mile 3.2 site not feasible. One or
two powerplants up to 15 MW.
• Marks Engineering 1977 Project -low diversion darn
at mile 3.2 with tunnel pipeline and penstock to
first-stage 5-r~ run-of-the-river powerplant with
second stage increase to 10 MW.
• Galliett 1977 Project -first-stage 5-MW project
per Marks with second-stage 165-foot darn at mile
5.2. Second-stage powerplants totaling about
10 MW would be installed at the darn or at the
first stage powerhouse.
Four sites have been evaluated since 1966, including seven
development concepts. Of the seven development concepts,
three may not be technically feasible for the following
reasons:
23
Development
Concept
Run-of-the-river
(50-foot-high)
Run-of-the-river
(50-foot-high)
Site
Creek
Mile 2.9
Creek
Mile 2.9
Capacity (MW)
1.8
(first stage)
2.7
(second stage)
Comments
Unknowns related to
sealing portions of
reservoir
Unable to meet
future energy
requirements
Unknowns related to
sealing portions of
reservoir
Unable to meet
future energy
requirements
Storage
(140-foot-high)
Creek
Mile 3.2
10 Technical feasibility
questionable because of
fault line through r
site, potential for
massive avalanches
into reservoir, and
unknowns related to
sealing more than
4,000 feet along the
right abutment
The 1966 A&L Engineering Project was apparently eliminated
'by Harstad-Galliett during evaluations that resulted in the
1975 development plan. In 1977, Galliett raised serious
questions about storage at mile 3.2 and indicated a high dam
at that site is not technically feasible.
Additional details of the 1975-1977 reports by Harstad-
Galliett and Marks Engineering are included in table 5. For
comparison purposes only, the storage development concept at
mile 3.2 has been included.
Conditions along Power Creek are such that any dam and
reservoir project will require extensive geologic explora-
tions to determine the technical feasibility of proposed
sites along the creek. Values given in table 5 are based on
data presented in previous Power Creek reports. Costs
included are reconnaissance-level and are based on quanti-
ties identified in previous reports and general estimating
tables and charts presented in appendix B. Estimates for
the large dams and spillways are based on estimating data
24 ..
N
U1
Table 5. POWER CREEK SITES SUMMARY
Latitude
Longitude
Development Concept
Drainage Area (sq m1)
Reservoir Storage (acre-feet)
Mean Annual Flow (cfs)
Net Effective Head (ft)
Rated Capacity (MW)
Average Annual Energy (MWh)
Dam
Type
Height (ft)
Pipeline
Length ( ft)
Diameter ( ft)
Penstock
Length ( ft)
Diameter ( ft)
Transmission Line
Length (mi)
Voltage ( kV}
Cost
Capital ($xl~6 )
Annual ( $x~O )
Unit ($xl0 ) /kW)
Creek Mile 3. 2
60°36'N
145°34'W 1 Run-of-the-river
19.5
0
208
360
5
30,000
Concrete diversion
10
5,500
8.0
1,500
2 -4.0
7.0
15
14
160
2.8
Creek Mile 3.2
60°36'N
145° 34 'W 2 Run-of-the-river
19.5
0
208
360
10
45,000
Concrete diversion
10
5,500
8.0
1,500
2 -4.0
7.0
15
19
320
1.9
Land Ownership Chugach National Forest
Creek Mile 3. 2 Creek Mile 4.6 Creek Mile 5. 2
60°36'N 60°37'N 60°38'N
145°34'W 145°33'W 145°33'W
Storage Storage Storage
18.9 16.7 15.2
63,000 40,000 39,000
208 162 160
450 500 500
12.3 10.63 10.5
59,000 3 51,000 50,000 3
Earth-rock fill Earth-rock fill Earth-rock fill
140 165 165
5,500 15,000 18,000
8.0 8.0 8.0
1,500 1,500 1,500
2 -4.0 2 -4.0 2 -4.0
7.0 7.0 7.0
15 15 15
52 63 65
394 339 336
4.2 5.9 6.2
Environmental Concerns Creek supports sockeye up to Ohman Falls, mile 2.6; natural barrier prevents
further migration upstream; also substantial runs of red, silver, and pink
salmon. Spawning takes place along shoreline of Eyak Lake and partly upstream
from the mouth of Power Creek.
1 Cost estimates include provisions to add a second 5-MW turbine generator to existing diversion structure.
~ Cost estimate for installation of 10-MW plant initially.
55-percent load factor.
included in the Bureau of Reclamation instruction series 150
section entitled "Estimating," latest edition. Resulting
estimates have been "factored" to Alaska conditions by
adding 60 percent for the small run-of-the-river project and
40 percent for the large earth-rock fill dam projects. The
reconnaissance-level estimates are adequate for use in
comparison of alternatives and to identify the current
feasibility of developing a Power Creek hydroproject.
POWER DEMANDS
Peak generation demands in the Cordova electrical system
have been projected to rise from 3. 5 MW in 198 0 to~~ MW
in 2030. 4\-@.S
Current and projected energy demands are fairly uniform
throughout the year, ranging from 8 percent of annual each
month during the November-through-June period to 9 percent
of annual each month during the July-through-October period.
Energy usage is currently at a 55 percent annual load factor
and is projected to remain at that level. Monthly and
annual projected energy demands for 1980, 1990, 2000, and
2010 are given in table 6.
POTENTIAL HYDROPOWER GENERATION
Hydrologic records are available for Power Creek from August
1947 to the present. Average annual flow is about 240 cfs,
with minimum flows in March of about 20 cfs and maximum
flows in September ranging up to about 5,000 cfs. Annual
discharges average about 170,000 acre-feet. Water year
1974-75, with a mean flow of 260 cfs, is considered an
average year; recorded flows for that year have been used in
'the power-generation calculations. Because of the similar-
ities of potential energy production, capital costs, and
installed capacity from sites at miles 4.6 and 5.2, only one
storage-type project will be discussed for the remainder of
this chapter.
Low flows during the winter-spring period limit the amount
of usable energy that can be provided by a run-of-the-river
hydroproject. Estimates of usable energy that could be
generated by 5-MW and 10-r~ run-of-the-river hydroplants
(mile 3.2 project) are given in table 6. An estimate of
usable energy generated by a 10-MW plant assuming 40,000
acre-feet of storage (miles 4.6 or 5.2 projects} is also
given in table 6. values given in table 6 are based on use
of the entire 1974-75 recorded flow and rough calculations
to determine approximate monthly values. Detailed operation
studies would probably result in lower values than those
shown, since the recorded flows are downstream of the proposed
diversion points. Also, some minimum flow may need to be
26
N
--..1
Table 6. POWER CREEK PROJECT DEMANDS AND POTENTIAL GENERATION
Mile 3. 2 Mile 3. 2 Mile 4.6 or 5.2
__EE~cted Ener~~ Demands
Usable Energy From 5-MW l
Run-of-the-river HydroElant
Usable Energy From 10-MW 1 Run-of-the-river H~droE1ant
Usable Energy From 10-~2 H~droE1ant With Stora~e &
1980 1990 2000 2010 1980 1990 2000 2010 1980 & 1990 2000 2010 1980 1990 2000 2010
--In million kilowatt ho~
Jan 1. 35 2.20 3.58 5.86 LOS 1.05 1.05 1.05 1.05 1.05 2.20 3.58 3.58
Feb 1. 35 2.20 3.58 5.86 0.80 0.80 0.80 0.80 0.80 0.80 )..< 2.20 3.58 3.58 OJ
March 1. 35 2.20 3.58 5.86 0.49 0.49 0.49 0.49 0.49 0.49 :> 2.20 3.58 3.58 ·ri
April 1. 35 2.20 3.58 5.86 o. 75 0.75 0.75 0.75 Same As 0.75 0.75 .... 2.20 3.58 3.58 I
May 1. 35 2.20 3.58 5.86 1.35 2.20 3.34 3.34 5-MW 3.34 3.34 Q.l 2.20 3.58 3.58 ..c::
June 1. 35 2.20 3.58 5.86 1. 35 2.20 3.58 3.60 Plant 3.58 5.86 -i-l 2.20 3.58 3.58 I
July 1.52 2.47 4.03 6.59 1. 52 2.47 3.60 3.60 4.03 6.59 4-l 2.47 4.03 5.05 0
Aug 1. 52 2.47 4.03 6.59 1. 52 2.47 3.60 3.60 4.03 6.59 I 2.47 4.03 5.05 !=:
Sept 1.52 2.47 4.03 6.59 1.52 2.47 3.60 3.60 4.03 6.59 :J 2.47 4.03 5.05 )..<
Oct 1.52 2.47 4.03 6.59 1.52 2.47 3.60 3.60 4.03 6.59 0 2.47 4.03 5.05 3:00
Nov 1. 35 2.20 3.58 5.86 1.35 2.20 3.58 3.60 3.58 4.74 ::E:<:J'\ 2.20 3.58 3.58 1.--1
Dec 2.20 3.58 1. 35 1.57 1.57 1.57 l1) 2.20 3.58 3.58 ....
<!) 0
"'""' Annual 16.88 27.48 44.76 73.23 14.57 21.14 29.56 29.60 31.28 44.96 :J 27.48 44.76 48.84 til
til
!<!!
Percent of Annual Demand by Hydro 86 77 66 40 70 61 100 100 67
Thirty-Year Average Annual Usable Energy ------------24.53-----------------27.10--------------35.02--------
1 Based on stream flow records for water year 1974-1975, gaging station No. 15216000, 1 mile upstream from Eyak Lake.
2 Assuming a usable storage capacity of 40,000 acre-feet.
maintained within the streambed. Comparison of the table 5
values indicates a 10-MW run-of-the-river hydroplant would
not produce any more usable energy than a 5-MW plant until
the year 2000 and probably would not be justified unless
storage is available. With storage, the Power Creek project
could essentially meet Cordova demands through the year
2000. By the year 2010, only about two-thirds of the demand
could be met by Power Creek.
FEASIBILITY EVALUATION
To compare the three alternative projects, capital costs
have been annualized, utilizing repayment factors for 7 percent
30-year funds. Resulting costs per kilowatt-hour for the
30-year average annual usable energy generated are as follows:
Annual Usable Cost
Project Cost Generation Eer kWh
5-MW run-of-the-river $1,290,000 24.53 GWh 5.3¢
10-MW run-of-the-river $1,850,000 27 .10 GWh 6.8¢
10-MW storage $5,574,000 35.02 GWh 15.9¢
If the cost comparison is on an incremental project basis
(assuming 5-MW run-of-the-river base project with added 5-MW
run-of-the-river and storage contributing only the incremental
increase in usable generation), the following comparison
results:
Project
5-MW run-of-the-river
(base project)
Addition of 5-MW
run-of-the-river
Addition of storage
CONCLUSIONS
Incremental
Annual
t
$1,290,000
$ 560,000
$3,724,000
Incremental
Usable
Generation
24.53 GWh
2. 57 GWh
7.92 GWh
Cost
per kWh
The numbers above indicate the 5-HW run-of-the-river hydro-
project is probably feasible strictly on a fuel-replacement-
cost basis and that the second 5-MW run-of-the-river plant
will probably be feasible in the near future, especially if
the value of capacity is taken into account. Costs shown
are for the development project only and do not include any
CHZ."1 1-l't~c... tr J(.~Tvti!c.v;-1\/t:; r~nr S'-3f/./t'W;'..,
,::,c,.v~ Fo.c.. ~6-A./ftrtv/rY ra ~-~e~D~v~4L--------
28
rehabilitation costs to the existing powerhouse and distribu-
tion system. Storage, however, does not appear feasible now
and may not be in the future unless a lower cost reservoir
site can be found. Even if the mile 3.2 site were found to
be technically feasible, the cost of incremental usable
energy would be about 30 cents per kilowatt-hour.
Results of the preliminary evaluation of Power Creek indi-
cate more detailed field investigations should proceed on
the proposed run-of-the-river project. The following detailed
description of the facilities required for that project is
quoted directly from the Marks Engineering Report dated
1977; it covers the run-of-the-river project at mile 3.2.
MILE 3.2
1. Construct 2-1/2 miles of single-lane, gravel-surfaced
road with 10 percent maximum grade, from the vicinity
of the north end of Eyak Lake, to the diversion dam
site. Build close above pipeline bench where possible,
to permit crane reach out over pipeline bench and for
protection of pipeline bench from erosion, falling
rock, etc. Establish cut slopes for long-term sta-
bility. Remove and dispose of excavated material, or
build fill slopes as permitted by the U.S. Forest
Service.
2. Construct about 6,000 feet of pipeline bench, from the
surge tank location 1,500 feet northeast of the USGS
Gauging Station, to the tunnel entry near Ohman Falls.
Establish cut and fill slopes for long-term stability.
Remove and dispose of excavated material, or build fill
slopes below bench as permitted by the u.s. Forest
Service.
3. Divert and channel flow of Power Creek along southeast
side of valley from Mile 4.8 to Mile 3.2, to promote
settling of bedload of sand and gravel in natural
depression in southeast side of valley.
4. Construct about 1,500 feet of tramroad up hillside
along penstock route from powerhouse site to surge tank
location.
5. Construct about 700 feet of 7' X 8', horseshoe-section,
fully-lined, low-pressure tunnel in loose rock by
conventional tunnelling methods -such as drilling,
blasting, muck removal and placing tunnel sets, spiling,
rock bolts, mesh, gunite and concrete lining.
6. Construct about 800 feet of desilting channel from
tunnel entrance to headworks of diversion dam, via
Scout Lake.
29
7. Construct about 5,500' of 8-foot diameter, low-pressure
steel pipeline, from the surge tank location, along the
pipeline bench, to the tunnel exit. Fabricate pipe
locally from 1/4 inch steel plate by rolling and auto-
matic submerged arc welding of seams. Each pipe shall
be cleaned, lined, coated and provided with hydraul-
ically-formed bell and spigot end, which shall be
sealed by mechanical and hydraulic compression of a
rubber ring gasket. Pipe shall be supported above-
ground on concrete bunks to permit inspection and
maintenance.
8. Construct low diversion dam consisting of the following
features:
a. Overflow weir with standard crest and upstream
face inclined 45° to pass ice
b. Sluiceway
c. Headworks
d. Steel sheet pile cutoff walls
e. Stilling basins for overflow weir and sluiceway
f. Concrete upstream and downstream aprons
g. Stoplog slots, stoplogs and stoplog hoists at
sluiceway headworks
h. Radial gates in headworks and sluiceway, with
deicing equipment for winter operation
i. Trashrack, trashrake, and trashrake hoist at
head works
j. Reverse filters beneath overflow weir and riprap
k. Riprap from nearby slide
1. Sand and gravel from valley floor
m. Left and right closure dikes consisting of riprap
upstream face, sand-gravel embankment, clay-aggregate
impervious element and gravel downstream face
n. Avalanche diversion mound
9. Construct steel standpipe differential surge tank.
10. Furnish and install 2, about 1,500 foot long, 4-foot
diameter steel penstocks to each turbine using surplus
high-pressure line pipe from trans-Alaska pipeline
project.
11. Furnish and install 2 -7,500 horsepower vertical
Francis turbines with welded-steel scroll cases and 2 -
5,000 kilowatt, 12,500 -15,000 volt generators.
12. Furnish and install remote control and alarm equipment,
protective devices and switchgear for generators.
13. Construct reinforced-concrete powerhouse founded on
solid rock, with draft tubes discharging into Power
Creek.
30
14. Furnish and install 12,500 feet of 15,000-volt sub-
aqueous power cable. Install in trench along Power
Creek Road to north end of Eyak Lake with splices in
distribution manholes on northwest shore of lake.
Cable to extend from powerhouse to existing lakeside
power plant and switchyard.
Figure 4 shows the mile 3.2, 4.6, and 5.2 site locations and
appropriate project components of the most feasible alternative.
31
. ,--
·_!I
28 27
l \ --"'---. -~--/ ___ .. ,.;
)-'"'~ '\
t I
. :t "\ 16 \ •., ; ·-:--_.,__ 1
i . ('.,."\ \ /
.\~~·
I \ i_/) "-. \_
-// •" { :< \, \ \
.(
_ _ .,. / v:M -. · . •, ~ ..... ,.,,,./ I ~·~ ~~~rirt~l . "' tf. -~.r /~2CJ', \ , ( . I. .,"Q : JV '\ \ , • ---· • :e~ \ " .}t ,· ... ··r-~t1:~~:·· foes :t4 ·. · .Cat) ' QO ; · /..& .~ \ -.) , .~,"" i --!._ j . · .. ( '---, .... · : '\ ; : "· J -'. '· ~ 1 • • ·r'' -~·"•' " "-·---. -~.,-:.~ ,.--;-/--lA·: ~----' ·-------......;j-· ·---~. --'\-·-·-~-·ft~·---... ---'\"--~ '\ :l' ' H-i _,,,,,,,;;n :{~ . J ~-.-:'}}!"/ ,-/ ,;'',_' ,,· .{ /,
0
o;:-:··.,___J·----/( y" f/ .; : ----~ ---i \ \ -...:;, · ~-l } , .'
1
, .
• •• ) / -·--., ._i ', \-1 : ~;:., J \ _; ; ! • . / I \(,
r-\. DAM
•••••••• FLUME
PENSTOCK •....•....• TRANSMISSION LINE • POWERHOUSE
ACCESS ROAD
-.._ --I ) I \ ~\ .. \ ·' ( '~J / /' t,fo 1'--,..,_ • . . , _, \ , . . ... ,, --ct( ·
•. v'--1' I \0 ,.•·' \ :"' ,_ -· // I
~ v __ ! ,,,, .,2 / ,/1 ,/ {i!·-.:.!.
______ ...... -~--_ ...... -,: 1 ,., •. ---e;. -.-· / !_ .. ..-"" ~3 :
.. ,·/i9:oi-:.c..--~--c. ~-:hhJ · 1· .-/.. / . ; 1--..... ~ i . · \I ... '., . . .. . ; I ' ' -...... / ! ,. ,. $. -t ~ ( '\ "D 'i: ~ j· . ,-1
( I ;· ' 1' . /~I... ' ' ---. . . • ' "' . / ;\: -~ j / i / . . . ~_g;..( -' -·.. . ,~ ~\...!'{..:. -~--~ill -' u .«•"'C? I I "-( . ~----__/ "' o \ I , .\j"--,J___: / {_ oo J : /' ,_ ,~ ~-~:i-' I -~v3-9.~~r"~·h::k ~~-,.·~,-~ ~---~. i~ ~~-m-~~----~~ ·)-·:.i ·--~~-!=~~~---:~;:J~-;c::~~7~~~~L ,.~~~'--f
@
0 4000
Scale in Feet
// \ ' ~-<·""'-.:.~"'! / ~ . -;r
2 7 -j , -~,.,..r 26 r ._.~ '
3 3
) ~
FIGURE 4
POWER CREEK
HYDROPOWER SITES
•• Chapter 5
•• COMPARISON OF COMMUNITY POWER NEEDS AND HYDROPOWER
POTENTIAL
SMALL HYDROPOWER SITE SCREENING PROCESS
An initial screening of hydropower sites can be made by
comparing the present worth of each hydropower site to the
present worth of the community's total diesel requirements
for the next 50 years. The present worth of diesel for this
comparison is the present worth of all the diesel generation
needed to meet the projected community needs for the next 50
years. The present worth of the hydropower is the present
worth of the particular hydrosite development, which may or
may not meet the community's need.
If the ratio of diesel power present worth to hydropower
present worth is greater than 1.0, the sites in question
pass the initial screening. Since the present worth of all
hydrosites is much less than the present worth of the diesel
requirements for Cordova, a ratio of greater than 1.0 occurs
in all cases. All sites for Cordova therefore pass the
initial screening process. For example, the highest present
worth of a hydropower site was found to be $3.55 million in
comparison to the present worth of the next 50 years of
diesel generation in Cordova at 5 percent escalation or
$124.3 million. A diesel/hydro present worth ratio of 35.0
is the result. The remaining sites produce a ratio of
greater than 35.0.
The second screening effort involves the calculation of the
present worth of the diesel alternative. The diesel alterna-
tive is defined as the amount of diesel-generated energy
that is equivalent to the energy produced at a particular
hydropower site. This is commonly called the fuel replace-
ment analysis; but this analysis includes the capital equip-
ment and operation and maintenance costs for the diesel
alternative as well.
Table 7, which is based on a-percent, 2-percent, and 5-percent
fuel escalation above inflation, shows the present worth of
the hydropower sites and the present worth of the diesel-
generation alternative. The ratio of the present worth of
the diesel to the present worth of the hydropower site is
also presented.
Conclusions
The screening of the potential small hydropower sites for
Cordova resulted in the following general observations. The
cost of a hydropower site development is directly linked to
35
Table 7. PRESENT-WORTH COMPARISON OF SMALL HYDROPOWER SITES
AND DIESEL-GENERATION ALTERNATIVE
Diesel/Hydro
Present Present Worth
Hydropower Present Worth of 6 Worth of Diesel Ratio for Fuel
Sites HydroEower ($x10 ) Alternative ($xl0 6 ) Cost Escalation of
0% 2% 5% 0% 2% 5%
Humpback
Creek No. 1 3.55 3. 47 4.35 6.8 9 0.98 1.23 1.94
Heney
Creek No. 2A 2.14 0.8 5 1. 06 1.68 0.40 0.50 0. 7 9
No. 2B 1. 77 0.44 0.55 0.88 0.25 0.31 0.50
Hartney
Creek No. 3A 3.29 0.94 1.18 1.87 0.29 0.34 0.57
No. 3B 2.90 0.78 0.98 1. 55 0. 27 0.34 0.53
Crater
Lake No. 4 2.18 1. 51 1.89 3.00 0.69 0.87 1. 38
Unnamed w Falls No. 5 2.8 9 0. 7 5 0.94 1.49 0.26 0.33 0.52 0'1
11 • 'f ' , " ' 1 ' ! 1
the installed capacity at the site. The benefit of a site
is directly linked to the energy produced.
For the run-of-the-river projects considered in this study,
lack of wintertime streamflows gives an average 35-percent
capacity factor for all seven sites studied. Hydropower
sites with such low capacity factors cannot be expected to
be economically feasible unless they are ideally suited to
local power needs.
Since the produced energy from the sites is so small compared
to the community's energy demand, all plants would operate
24 hours a day during 6 months of the year. As a result of
this seasonal operation, other types of power, such as
diesel generation, would have to be used to take care of the
remainder of the community's needs.
Storage-type developments at the same sites would cost more
than run-of-the-river types because of the physical facilities
required, the safety issues associated with dams, and the
mitigative measures to minimize environmental impacts.
However, diurnal flow fluctuations lagging peak demand
periods might require some daily storage-type development
and should be considered in further studies.
The second screening indicates that two sites are feasible,
and these should be studied in more detail. Humpback Creek
and Crater Lake are situated north of the City of Cordova.
POWER CREEK SITES SCREENING PROCESS
The same screening process as discussed for the small hydro-
power sites was utilized in evaluating development concepts
shown in previous reports on Power Creek prepared during the
period 1966-1977. The four alternatives considered are
listed in table 8, which shows the present-worth comparison
and the ratio of diesel present worth to hydropower present ~~
worth. The ratio for the four alternatives ranged from 1.8
to 7.7. All sites on Power Creek therefore pass the initial
screening.
The second screening process includes the present-worth
calculation of the diesel alternative, as discussed previously
for the small hydropower sites. Table 9 shows the present
worth of Power Creek hydropower sites and the present worth
of the diesel-generation alternative at a-percent, 2-percent,
and 5-percent fuel escalation. The ratio of the present
worth of the diesel to the present worth of the hydropower
site is also presented.
37
Conclusions
All of the proposed Power Creek development concepts can
meet a substantial portion of Cordova's future power needs.
Low flows during the winter and early spring produce annual
capacity factors of 68 and 51 percent for the 5-MW and 10-MW
run-of-the-river alternatives and 55 percent for the storage
alternatives at miles 4.6 and 5.2. The most desirable
alternative in table 9 is the 5-MW run-of-the-river project
with a diesel/hydro present worth ratio of 3.6, followed by
the 10-MW run-of-the-river project at mile 3.2 and the
storage project at mile 5.2 with a ratio of 1.1. It is
therefore recommended that the initial 5-MW run-of-the-river
alternative:-with provisions for staged development, be
~lven further CQ!l~~-Storage capac-rry upstream of
mile 3.2 on Power Creek would produce additional generation
flexibility. The detailed feasibility of this type of
development concept should be studied concurrently with the
run-of-the-river project.
38
..
w
\.0
Table 8. PRESENT-WORTH COMPARISON OF POWER CREEK HYDRO-
POWER SITES AND COMMUNITY'S TOTAL DIESEL NEEDS
Development
Concepts
Run-of-the-river
Run-of-the-river
Storage
Storage
Hydropower
Sites
Mile 3. 2
(5 MW)
Mile 3. 2
(10 MW)
Mile 4. 6
Mile 5.2
Present Worth
of Hydro gite
($ X 10 )
16.2
23.5
67.8
69.1
Present Worth
of Dies61*
($ X 10 )
124.3
124.3
124.3
124.3
* Present worth of community's total generating facility and
fuel needs with fuel escalated at 5 percent annually.
Diesel/Hydro
Present Worth
Ratio
7.7
5.3
1.8
1.8
1..,
Table 9. PRESENT-WORTH COMPARISON OF POWER CREEK HYDROPOWER SITES AND
DIESEL-GENERATION ALTERNATIVE
Development
Concepts
Run-of-the-
river
Run-of-the-
river
Storage
Storage
Hydropower
Sites
Mile 3.2
( 5 MW)
Mile 3.2
( 10 MW)
Mile 4.6
Mile 5. 2
Present Wor6h
Hydro ($x10 )
16.2
23.5
67.8
69.1
Present Worth of Diesel
Alternative for Fuel C~st
Escalation of: ($x10 )
0% 2% 5%
27.3 35.1 57.9
32.3 42.9 74.6
33.9 45.5 54.6
33.4 44.7 78.9
Diesel/Hydro Present
Worth Ratio for Fuel
Cost Escalation of:
0% 2% 5%
--
3:9 (1;7 2.2
1.4 1.8 3.2
0.5 0.7 0.8
0.5 0.6 1.1
•• •• BIBLIOGRAPHY
Galliett, Harold, H., Jr., Power Creek Project, Cordova,
Alaska, 12 pp letter report, 1977
Johnson, Arthur, Preliminary Report on Water-Power Resources
of Power Creek Near Cordova, Alaska, u.s. Geological Survey
open-file report, 37 pp 1949
Miller, D. J., Geology at the Site of a Proposed Dam and
Reservoir on Power Creek Near Cordova, Alaska, U.S.
Geological Survey Circ. 136, 8 pp, 1951
Alaska Department of Fish and Game. Alaska's Wildlife
and Habitat, Volume II, 1978
Alaska's Fisheries Atlas, Volumes I and II, 1978
A&L Engineering, Engineering Report on Cordova Power
Project for Cordova Public Utilities, 19 pp, 1966
Bureau of Reclamation, Instruction Series 150, Estimating
Section
Cordova Comprehensive Development Plan, 1976
Harstad-Galliett Engineers-Planners, Power Creek Hydroelectric
Project, EPC No. 2760, Progress Report, 31 pp, 1976
Juneau, Alaska, Water Resources Atlas, prepared by OTT Water
Engineers, Redding, California, April 1979
~arks Engineering, Power Cost Study, 1978-1992, 241 pp, 1977
Marks Engineering, 1977 Power Cost Study Supplement A,
Hydroelectric Run of River Alternatives, Power Creek, 59 pp,
1977
North Pacific Consultants, Preliminary Engineering Review
of Water Supply and Electrical Generation for Cordova Public
Utilities, 20 pp, 1959
Review Draft of Cordova Coastal Management Program, 1979
(subject to change)
University of Alaska, Arctic Environment Information and
Data Center, Alaska Regional Profiles, Southcentral Alaska
(No date)
U.S. Department of Agriculture, Forest Service, Region 10,
Benefit/Cost, Salmon Habitat Improvement, February 1969
41
U.S. Geological Survey; quadrangle sheets for appropriate
areas (1:63,000)
u.s. Army Corps of Engineers, Hydrologic Engineering Center,
Reconnaissance Studies for Small Hydropower Additions,
Davis, California, July 1979
42
•
•• Appendix A
•• PHYSICAL SETTING AND HISTORY OF CORDOVA
COMMUNITY LOCATION
Cordova is located on the south-central coast of Alaska,
160 miles southeast of Anchorage and 25 miles west of the
Copper River delta. The city is situated on Orca Inlet near
the eastern entrance to Prince William Sound, east from
Hawkins Island. The extent of the settlement is confined by
Mt. Eyak to the north, the abrupt foothills of the Heney
Range to the south, Eyak Lake to the east, and Orca Inlet to
the west. Most of the city's development occurs on a low
divide between the waters of Orca Inlet and Eyak Lake, on
the foothills of Mt. Eyak, and along both the north and
south shores of Eyak Lake.
Cordova's physical setting is characteristic of the entire
Prince William Sound area, ringed by the Kenai-Chugach
Mountains and the Chugach National Forest, and defined by a
deeply indented coastline formed by glacial activity. The
mountains, rising abruptly to elevations of 3,000 to 6,000
feet, present a formidable barrier to transportation routes
from the interior. Of the three cities on the sound, only
Cordova is not serviced by overland transportation. Whittier
has railroad access from Portage on the Seward Highway, and
Valdez is linked by the Richardson Highway.
Cordova is presently accessible only by air or water. The
city has daily jet service to Anchorage and Juneau, as well
as a number of smaller aircraft operating on an air taxi or
charter basis. Cordova is also served by the Alaska State
Ferry System.
The Kenai-Chugach Mountains act as buffers against major
wind and storm fronts in the area of Cordova. Although the
city enjoys a relatively mild year-round climate for its
northerly location, the annual average precipitation is
120 inches. Approximately one-half the precipitation is
in the form of heavy wet snow, resulting in the most strin-
gent snow-load restrictions on construction in the entire
state.
COMMUNITY HISTORY
The present city of Cordova was settled as a direct result
of coal, oil, and copper discoveries at the beginning of
this century. Oil was discovered in the Katalla area south-
east of Cordova in 1902, and the area subsequently became
the site of Alaska's first producing oil well.
A-1
About the same time, the nearby Bering River coal fields
were also being developed. By 1905, the oil and coal oper-
ations were in great need of good port facilities. When
Katalla proved to be unsatisfactory for such facilities,
Cordova was sited as the nearest location with a good deep-
water harbor. Cordova soon became established as a trans-
portation and support center for these operations.
Development of the Bering River coal fields was halted by
President Theodore Roosevelt's withdrawal of Alaska's coal
lands from entry in November 1906. Plans to construct a
smelter near Cordova were scrapped; and because of the
collapse of the coal mining industry, a Katalla railway
project was abandoned.
In 1906, the Kennecott Copper Company began construction of
the Copper River and Northwestern Railroad in conjunction
with development of its Chitina River valley mining claims.
By 1911, the railroad line extended to the Kennecott copper
mines. Successful completion of the railroad and the tre-
mendous copper yields made Cordova prosper in spite of the
terminated coal mining operations.
Town lots were sold in 1908, and Cordova was incorporated as
a city during the same year. By 1910, Cordova had a popu-
lation of 1,152. For the next 30 years, Cordova continued to
function primarily as the transportation and service center
for the Kennecott copper mining operations and the Katalla
oil fields. Among industries that became established on
much smaller scales during those years, timber and fishing
were the most important.
A significant number of the people included in the 1910
population figure left Cordova upon completion of railroad
construction in 1911. By 1920, the population of the city
was approximately 960 persons.
The mainstays of Cordova's economy folded in the 1930's.
The Katalla oil fields were closed following the burning of
the refinery in 1933. The annual output of the copper mines
began to decline steadily after record high extractions in
1927. The mines were finally closed in 1938, followed by
the Copper River and Northwestern Railroad in 1939. By that
year, Cordova had a population of 980 persons and an economy
left almost entirely dependent on the fishing and fish-
processing industry.
Cordova made the transition in its economic base fairly
smoothly. Since 1940, the city has experienced slow popu-
lation growth with the exception of a slight decline between
1950 and 1960. Fishing and fish processing have continued
to be the primary economic activities in the city. Salmon
A-2
remains the principal species caught and processed, although
the industry has become more diversified in recent years,
resulting in greater year-round employment.
The earthquake of 1964 altered the face and future of Cordova.
The land in the Cordova area was raised by an average of
6 feet, leaving many docks useless. The city undertook
major dock and boat harbor improvements to make these facil-
ities usable again. Dredge spoils from these improvements
were used to create a 20-acre industrial park adjacent to
the city dock.
A-3
•• Appendix B
•• COST ESTIMATES
The methods used to determine capital and operation and
maintenance costs for each hydroelectric site are presented
in this appendix. The site development cost estimate form
shown was filled out. Estimating data were provided from
the cost curves and tables that are included.
B-1
1.
2.
3.
4.
5.
6.
7.
8.
9.
Location
SITE DEVELOPMENT COST ESTIMATE
cfs
ft
Site Stream
Diversion flow -
Diversion Elev -
Total Head -
Potential power -
ft -delivery losses ( ____ ) = eff. head
Item
Diversion Dam LF
~'ish Ladder
Power turnout
headworks (in-
cludes fish
screen if proj-
ect requires
fish passage)
Delivery system
Canal
Lawhead pipe --~
Penstock-~
Powerhouse kW
Distribution
Site Access
Mobilization
Mise: Bonding,
insurance,
diversion, and
care of water
SUBTOTAL
kW
$ 7/78
~ Unit Unit Cost in SEA
1
1
CY
LS
LS
LF
LF
LF
LS
mi
mi
LS
LS 10% of items
1 through 8
Contingencies 15%
TOTAL CONSTRUCTION
Indirect Costs 25%
TOTAL PROJECT COST
ANNUAL OPERATION AND MAINTENANCE
B-2
X 1.82
$ 10/79
SC AK
•
..
300
Ill .....
Ill ,__ 200 ~~ I=
1:)
(.) .. _
1:)
I" 1:J
~~
1:0 >-
1:,) 100
"':J :J
(.)
0
600
500
400
5
0
0 . 300
X
·W
200
100
0
1. Diversion Darn Costs
0 50
Diversion Length-ft
NOTE: Cost of concrete= $350/CY. This includes
foundation excavation and preparation,
formwork, steel, concrete and all labor.
100
2. Fishladder--5' vertical lift @ 3---/vf = $15,000
3. Power Turnout Headworks (no ice control)
~Without Fishscreens
0 50 100 150 200
Penstock 0-cfs
B-3
150
250 300
Q.)
~ .....
C"O
Q.)
(/)
co
!.'
U! ,_
co
0
0
+.. --.....
U!
0
(..)
4. Delivery System--Canal use 3/4 c'f pipe cost for same fJ o,.,
Low Head Pipe and Penstock
200 -
150
'
1001
50
0 L-----------------~------~--------~------~------~
0 ~ 100 1~ 200 2~ 300
F!ow in cfs
NOTE: Dollars per foot from manual, "Reconnaissance Studies for Small
Hydropower Additions," U.S. Corps of Engineers, July 1979.
Powerhouse
On most site we assumed an Impulse or cross-flow turbine
that can operate down to 10% of its rated capacity to take
advantage of low flow.
Cost based on Effective Head & Rated kW
Total Cost_ from "Reconnaissance Studies for Small Hydropower
Additions."
i3 '.' -.
..
..
..
"
•
..
Power Features Cost -Reconnaissance (Least Cost)
fJ) a::
<t
_J
_J
0
0
0 z
<t
fJ)
::>
0
:I:
1--
....
fJ)
0
(.)
MOTES:
15MW
IOMW
(!) z
7.5MW ~
a::
a::
0
5MW
3MW
2MW
tMW
I. Estimated costs are based upon a typical cr standardized turbine
coupled to a generator ei (her directly or through a speed increaser,
depending on the type turbine used.
2.' Cosb include turbine/generator and appurtenant equipment, station
electric equipment, miscellaneous powerplant equipment, powerhouse,
powerhouse excavation. switchyard civil works, an upstream_sl ide
gate, and construction and installation.
3. Costs not included are transmission line, penstock, tailrace con-
struction and switchyard equipment.
'L Cost base July 1978.
5. The transition zone occurs as unit types change due to increased head.
6. For a Multiple Unit powerhouse, additional station equipment costs
are $20,000 + $58,000x(n-1) where n is the total number of units.
7. Data for this figure was obtained from figures and tables in
Volumes V and VI.
B-5
~ a:: w z w
(!)
6. Distribution
Distribution Type
3-ph, 1-kV 0/H & U/G
1-ph, 5-to 15-kV concentric neutral cable
with 0/H & U/G routing
1-ph, 15-kV 0/H
3-ph, 25-kV 0/H
3-ph subtransmission 0/H
1-ph, 15-kV concentric neutral cable used
as Hd life submarine cable
1-ph, 25-kV submarine cable
3-ph, 25-kV submarine cable
...,
I •
ph phase
kV = voltage
0/H = overhead
U/G = underground
Site Access
Roads @ $100,000/mi
Trails @ $10,000/mi
8. Mobilization
MW
Rat~ng
o-0.2
0.2-0.5
0.5-2.0
2.0-5.0
5.0-10.0
0-0.5
0.5-3.0
3.0-10.0
"'!.:ox.
t~'is·t Inst:alleci
(mile) ..:::ost/Mile
1 $ 20,000
3 35,000
10 60,000
10 80,000
10 150,000
2 40,000
3 130,000
5 250,000
Assume all jobs will have to be mobilized from either Ketchikan or
Juneau
Barge wjtug@ $1,500/day
Move-in Load 1 day
Travel 2 days
Unload 1 day
Move-out Load ~ day
Travel
Unload
2 days
~ day
7 days @ $1,500 = $10,500
If access from barge landing to site is not a road, assume
site unloading and loac'ina bv heli~"'ort<>r @ $800/hr
(1,500-2,000 lb/~~t~·
2 10-hr days@ $800/:-r ~" $16,000
,..
Assume all above costs except fo;~ distribution are :tor Seattle fc,r July
1978 (ENR 3161)
Escalate to October 1979 (July 1979 ENR 3506 + 3 ate @ :i.%;'ruo
Then account for difference between Seattle and SE Alaska
Juneau = 1.58 Ketchikan = 1.59 Use 1.6
SEA SEA SE AK
7/78 X 1.14 7/79 X 1.6 = 7/79
Est. Est. Est.
SEA 1.82 SE AK or :::;
7/78 7/79
Operation and Maintenance Costs
Labor 30 days/year @ $300/day = $9,000
or $25/year/kW, whichever is largest
Materials $2/year/kW
Overhaul $5/year/kW
B-7
3600)
•• Appendix C
•• OPERATION AND MAINTENANCE COSTS FOR DIESEL GENERATION
The installed cost of diesel units in the 1-to 2-MW range
was estimated at $350 per kW. Adding interest brought the
total investment cost to $485 per kW.
Equipment cost per kWh was calculated to average 1.1¢ per
kWh at a 50-percent load factor and 0.9¢ per kWh at a
60-percent load factor.
The units are expected to have a life of 90,000 hours with
major maintenance every 30,000 hours. Each unit would,
therefore, require a major overhaul twice during its life.
The overhaul cost for a 2-MW unit would be about $70,000.
Major maintenance would therefore total $140,000, or $70 per
kW for the unit's life. Routine maintenance would average
$30,000 per year, for a total $300,000 or $150 per kW for
the unit life. Total O&M would, therefore, average $220 per
kW. O&M cost per kWh was estimated at 0.5¢ at a 50-percent
load factor. In addition, lube oil costs are estimated at
0.4¢ per kWh and miscellaneous supplies and equipment costs
at 0.2¢ per kWh, bringing the total O&M costs to 1.1¢ per
kWh.
C-1