HomeMy WebLinkAboutGunnuk Creek Appendix DsnE ooi PRELIMINARY APPRAISAL REPORT
HYDROELECTRIC POTENTIAL
ANGOON
CRAG
HOONAH
FOR
HYDABURG
KAK£
KASAAN
KLAWOCK
STATE OF ALASKA
KLUKWAN
PELICAN
YAKUTAT
ALASKA POWER AUTHORITY
1977
prepared by UZI; R
Ry CornVIFy
T ROBERT W. RETHERFORD ASSOCIATES
POST OFFICE BOX 6410 FPROPE"TyOtAIaska Power Auhority
ANCHORAGE, ALASKA 99502 334 W. Sth Ave.
D. Hake
Two sites were considered worthy of investigation for
this study. The Sanborn Cutting Company developed a
small hydro plant on Gunnuk Creek circa 1920. Part of
the old wood stave penstock is still in evidence. The
City of Hake has constructed a timber buttress dam
across Gunnuk Creek with a crest at elevation 180 and
uses a portion of the flow for their potable water. A
new highway bridge is under construction.crossing
Cathedral Falls Creek approximately one -quarter mile
upstream from the falls. Highway access is available
to both sites and excellent materials for earth -fill
dams are abundant.
Gunnuk Creek
The mouth of Gunnuk Creek, in latitude 56°58'N, and
longitude 133°56'W, discharges into Keku Strait and
flows through the City of Hake.
There are 11.5 square miles draining to the diversion
dam at the 180-foot elevation. Discharge measurements
have not been made. The watershed is .low and lies in a
belt of comparatively low precipitation. The mean
discharge is estimated at 86 cfs or 7.5 cfs per square
mile and the nominal discharge at 10.cfs.
The existing timber buttress dam provides forebay
storage only. Storage for complete regulation would be
prohibitive to obtain at this site. A suitable storage
basin exists at approximate stream mile 3.5. Two earth
fill dams would be required, one on each fork of the
two southerly flowing branches of the stream. This
would create a reservoir with a surface area of 586
acres and provide 14,500 acre-feet of storage. This
would regulate 75 cfs flow at the existing dam.
A penstock 2800 feet in length would convey the water
to a powerhouse located at tidewater.
The power capacity is estimated at 875 kW primary and
1000 kW average. Two 900 kW units are recommended for
the installation. The voltage would be stepped -up to
7.2/12.47 kv and fed directly into the distribution
system. Transmission will not be required.
This development would also assure Hake of a reliable
source of potable water.
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Legend
'" , Anadromous Streams
�. Gunnuk-streams
' Other Non-USFS Lands
. USFS Lands
State Lands
- City of Kalte Lands
OSealaska Corporation Lands
OKake Tribal Corporation Lands
OConservation Easment
G
0
Existing Dam
Alpine Lake
Gu r
Legend
'\. Anedromous Streams Elevation Zones in Feet
Gunnuk-streams
O 0-25
a'- Potential Gage Site
Q 25.00000001
- 125
C. Intake Site
125,0000001
- 300
0. Powerhouse Site
300.0000001-350
Impoundment Dam
® 350.0000001
- 565
%L Run of River Penstock
O 565.0000001
- 675
O%hei Supplemental Flow Penstock
O 675.0000001
- 1,500
- Reservoirs
O 1:500,000001
- 3,920
o
25'
P
330' Intake Site
Alpine Lake Rs
Gunr
500' Intake Site
"Gun
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