HomeMy WebLinkAboutAkutan Site No. 4 for Alaska Power Authority 1980AKU
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AKUTAN
CORPS OF ENGINEERS
SITE NO. 4
FOR
RL:CEIVED
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,,~ASKA POWER AUTHORITY
ALASKA POWER AUTHORITY
Ll YCOPY
BY
R. W. RETHERFORD ASSOCIATES
INTERNATIONAL ENGINEERING CO., INC.
~lARCH 1980
PROPERTY OF:
Alaska Power Authority
334 W. 5th Ave.
Anchorage, Alaska 9950t
APA18/D
Report to:
Subject:
Date:
Weather:
Alaska Power Authority
Akutan C. of E. Site No. 4 Hydro Potential
February 21, 1980
Snow with brief periods of sunshine
Gusty winds
Temperature@ 10:00 A.M. 22°F
The stream flow near the mouth was measured to be 14 cfs on February 21,
1980 (Photo #1). The stream meanders through a relatively broad
flat valley at a fairly uniform gradient to elevation 80 (aneroid
barameter reading); a straight line distance of about 1.5 miles
(Photos 2 & 3). The flow at elevation 80 was estimated at 3 cfs on
the above date. The gradient steepens rapidly between elevation 80
and the summit at elevation 420 (Photo #4), a straight line distance
of about 0.5 miles. There was no perceptible flow above elevation
250 (Photo #5). At elevation 200, the flow was approximately
1 cfs. Numerous springs and seeps appear along the stream bank
between elevations 80 and 250 (Photo #6). Several small streams
and seeps appear along each side of the valley floor between sea
level and elevation 80 with the largest flowing about 2 cfs into
the valley from the southwest about one mile from the head of the
bay.
It was reported by the Akutan Village Chief that the stream sup-
ports a large pink salmon run in the first mile of the stream.
Although no commercial use is made of the pink salmon in the area,
the people of the village use the stream for sport and subsistence
fishing.
A powerhouse below elevation 80 would not be feasible as only
1 foot of head would be gained for each 100 feet of additional
penstock. An intake structure at elevation 200 with an average
estimated flow of 1 cfs and a powerhouse at elevation 80 would
produce about 7.5 kW of power. A transmission line 3.25 miles in
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length would be required to deliver the power to the Village of
Akutan.
Because of the low flow, impracticable reservoir storage, salmon
run, and transmission distance; this stream is not a viable hydro-
electric site for the Village of Akutan.
The Corps of Engineers Site No. 3 was examined and the power avail-
able and development costs were found to be a valid assessment.
Site No. 2 was evaluated and a slight modification from the Corps
Report was made. From field observation it was determined that an
additional 100 feet of head could be obtained by installing two
diversion structures with an infinitesimal loss of flow. Using the
Corps of Engineers assumption of 5 cfs as being good flow estimate
for a run-of-river site, a capacity of about 105 kW is available.
The tentative development scheme for Site No. 2 is as follows:
1. The run-of-river project would consist of two intake struc-
tures at approximate elevation 300 to divert the water down
the 1900 feet of 12-inch penstock. Transportation of con-
struction materials to the site would be by highline due to
the steep terrain and the total lack of any roads or vehicles.
The diversion structures would be constructed of sheet pile.
The powerhouse would consist of a modular unit containing
either a single or double runner impulse turbine and generator
with a maximum capacity of 200 kW and all required switchgear.
The energy produced by this unit would be transmitted by 0.7
miles of 25 kV URD cable submerged across Akutan Harbor and
0.5 miles of wood pole transmission line to Akutan.
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Preliminary Cost Estimate for Site No. 2
Item
Mobilize and Demobilize
Diversion Structures
Penstock (12 11 di a. )
Pre-packaged turbine generator, etc. (200 kW)
Transmission Line (1.2 mi.)
Substation
Subtotal
Contingencies 20%
Engineering Supervision & Administration 16%
Total
Cost
$ 500,000
125,000
200,000
275,000
75,000
35,000
1,210,000
242,000
1,452,000
232,300
$1,684,300
The above represents a tota 1 capita 1 cost of $8,420 per kW of
installed capacity.
The following are annual costs including operation and maintenance
for a 50-year project life.
Interest Annual Total Annual
Rate Pa~ment O&M Cost
2% 53,645 2500 56,145
5% 92,300 2500 94,800
6-7/8% 120,090 2500 122,590
9% 153,610 2500 156,110
The following table portrays the cost per kWh based on various
interest rates and an amortization period of 50 years. Two figures
are given for each interest rate with one assuming that all power
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produced during the months of July through November would be util-
ized and 60% of the available power is assumed to be utilized
during the rest of the year. The second figure represents 100%
utilization.
Percent Amortization Interest Annual
Utilization Period Rate Cost
100% Jul-Nov 50 yrs. 2% 56,145
60% Dec-Jun
100% year around 50 yrs. 2% 56,146
100% Jul-Nov 50 yrs. 5% 94,800
60% Dec-Jun
100% year around 50 yrs 5% 94,800
100% Jul-Nov 50 yrs. 6-7/8% 122,590
60% Dec-Jun
100% year around 50 yrs. 6-7/8% 122,590
100% Jul-Nov 50 yrs. 9% 156,110
60% Dec-Jun
100% year around 50 yrs. 9% 156,110
Respectfully submitted,
Ga;zf,£~17
Carl H. Steeby, P.E.
Principal Civil Engineer
Robert W. Retherford Associates
CHS:ng
Acknowledgments:
Mr. Luke Shelikoff, Chief-Akutan Village
Plant Manager Craig Cross and Crew of the
Western Sea - a tanner crab processing vessel -
Cost
$/kWh
0.080
0.061
0.134
0.103
0.174
0.133
0.221
0.180
who were kind enough to provide food, lodging and a skiff
to the head of the bay.
Enclosures: Photographs.
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PHOTO NO. 1
Stream near mouth at West end of Akutan Harbor.
Flow measured at 14 cfs on 2-21-80.
PHOTO NO. 2
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Westerly view from Akutan Harbor. Summit of main
stream channel is shown in approximate center of photo.
The large mountain in the background is not in the
watershed.
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PHOTO NO. 3
Easterly view toward Akutan Harbor from approximate
elevation 80.
PHOTO NO . 4
Upstream view of main stream channel taken at elevation
200 showing summit at elevation 420.
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PHOTO NO. 5
Easterly view of valley from elevation 250. There
was no flow at this elevation on February 21, 1980.
PHOTO NO. 6
Upstream view of main stream channel at elevation
200. Flow estimated at 1 cfs on February 21, 1980.
Note springs and seeps along stream channel.
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