HomeMy WebLinkAbout2000 HDR March exec sumryANGOON
ExEcuTivE SUMMARY
FOR
KOOTZNOOWOO
• 40
I�
MAR Hy WOO
ANGOON HYDROELECTRIC PROJECT
FEASIBILITY EVALUATION REPORT
EXECUTIVE SUMMARY
A. INTRODUCTION
Kootznoowoo Incorporated (Kootznoowoo) is the village corporation for the city of Angoon,
which is located on the west side of Admiralty Island approximately 60 miles southwest of
Juneau, Alaska. Kootznoowoo is considering the development of the Angoon Hydroelectric
Project (Project) as a means to lower the cost of power generation in Angoon, directly benefiting
the residents with lower electric bills and indirectly stimulating the local economy. The Alaska
National Interest Lands Conservation Act of 1980 (ANILCA) specifically provides to
-,: Kootznoowoo the right to develop the Project subject to conditioning authority by the U.S.
Forest Service.
B. ANGOON LOADS AND RESOURCES
Electricity is currently supplied to residents and businesses in Angoon by the Tlingit-Haida
Regional Electric Authority (T-HREA) at rates that are some of the highest in Alaska (about 32.5
0/kWh). The average load in Angoon is currently about 230 kW, and the peak load is about 425
kW. To meet the existing loads, T-HREA has a single power plant in Angoon with two diesel
generators with an aggregate generating capacity of 1,115 kW.
Potential new electric loads are possible in Angoon due to the recent distribution of over 600
homesites to Kootznoowoo shareholders and the proposed siting of a Alaska Marine Highway
System near Angoon by the Alaska Department of Transportation and Public Facilities. Practical
alternatives for supplying the existing and new loads are: 1) continuation of diesel generation,
and 2) development of the Project if sufficient funding assistance can be obtained (as is relatively
common for small hydro developments in Alaska).
C. PROJECT SETTING
The Project would be located on Thayer Creek approximately 6 miles north of Angoon, as shown
in Figure ES-1. Thayer Creek flows out of Thayer Lake for about 6 miles at a gentle grade
through a broad forested valley, then steepens for 6,800 feet through a narrow forested canyon,
and finally flattens again for 2,000 feet before flowing into Chatham Straight. The Project will
develop the energy potential in the steep section of the stream. The lower section supports
anadromous runs of pink, chum, and coho salmon, and the upper section supports cutthroat trout.
It is unknown if the steep section of stream supports any resident fish.
The average flow in Thayer Creek is about 370 cfs, and can vary from 25 cfs during cold periods
in the winter to over 2000 cfs during storms in the fall and winter.
The Project area is in the Kootznoowoo Wilderness on Admiralty Island, an area with no roads
and few trails. The lack of access will have a significant influence on the ability to develop the
Project economically, both from the direct cost of providing access during construction and
operation and from possible opposition to the Project's development.
HDR Alaska, Inc. ES-1 March 2000
3
s
Angoon Hydroelectric Project Feasibility Evaluation Report
Kootznoowoo, Incorporated Executive Summary
D. ALTERNATIVE ARRANGEMENTS
The initial phase of the work documented by this report was to evaluate several alternative
arrangements for the Project so that a preferred alternative could be selected. Three primary
alternative arrangements were evaluated, as follows:
3 • Alternative 1 - - Pipeline and Penstock
• Alternative 2 - - Directional -Drilled Tunnel
• Alternative 3 - - Conventional Tunnel
A comparison of some of the primary costs and benefits of these three alternatives is shown in
j Table ES-1.
Additional alternatives looked at the cost and benefits of decreasing the installed capacity to 500
kW, using overhead or buried transmission instead of submarine, and adding a water supply
pipeline along the submarine transmission line. At a review meeting on April 26, 1999,
Kootznoowoo selected Alternative 1 - - Pipeline and Penstock as the preferred alternative. In the
second phase of work, this preferred alternative was refined to develop the selected arrangement,
as described below.
E. SELECTED ARRANGEMENT
1. Project Features
Figure ES-2 provides a general plan of the selected arrangement for the Project. The major
features are as follows:
Port facilities will include a temporary barge landing, mooring buoys, and a garage for housing
operation and maintenance vehicles. The port facilities will be located approximately 1.8 miles
south of the outlet of Thayer Creek where an existing peninsula provides secure anchorage and
protection from storms.
There will be three access roads for the selected arrangement. The first will lead from the port
facilities to the power plant, and will be approximately 1.9 miles long. The second access road
will lead from the powerhouse access road near the powerhouse to the diversion dam/intake
structure, and will be approximately 7,200 feet long. A 1,000-feet long spur from this road will
provide access to the top of the surge tank during construction. The third access road will be
from the port facilities to Kootznoowoo Inlet, and will be a minimum -construction road
primarily for installation of the transmission line; it will also provide emergency access to the
Angoon facilities by all -terrain vehicles.
The diversion dam will be located approximately 8500 feet above tidewater at the head of a
very steep section of rapids about 250 feet above sea level. The dam will be primarily a concrete
wall approximately 10 feet high, with grouted rockfill on each side for stability.
The intake structure will be located on the north abutment of the diversion dam, and will be
primarily a concrete structure housing a trashrack, transition section, shutoff valve, sluiceway,
and control facilities. Modified shipping containers will be incorporated in the construction of
the intake structure, and will initially function as diversion flumes to bypass water around the
s
damsite during construction.
HDR Alaska, Inc. ES-2 March 2000
i
W
W
a
Si
G*.
O
z
O
un
O
U
y `
O
d:
O
O
O
O �O�yy..
C
p
m
y
,
O N
U
N
.�;
}'x�
0
30
°off
�b
3
eb
3
�b
d
o0
O w
o
C7
0
0
o
U
Y
O O
U
rdx
O
b N
t
0008
3
H
1
o
c
b
3
y o
o
o
o
,a°
o
bw
°�°G
a
i
i
oti�
wq
o
b
b
3
3
U`°9��c�
a
a
L _ '
s"JI
o
0
y
y r
O
U
y
td
p
U m O
O
O
_A
O O O
O
b
U
4 w O
OLi:V
vNi
'
ion
3
3
3
x°
a
a
a
Abe
x
x
�
r`yG:
O
^ k
� •d
a
w o N
>
(7
N
.0
yAIRo.p
d
3
p
0
q
ro
q
o
bb
oqm
m
ja=CD
0
o°
0
g
3
x
o1
x
a
E4
sin
a
v LV
wO
Y
r sk '.t,
.0
U
i7Xr
f�/l
0
Lys.
U
N
w
to
Id U
«S W
U
x
O
o
'�
m
sro,ci
.
O0
45
.0
O
Y
Arn
O
O O
LL
N
of +U-'
F'
.U+
q
W U
A. U
O
0
U P;
Pp 0
Pp ¢
a;
M
co
w
I
Angoon Hydroelectric Project Feasibility Evaluation Report
Kootznoowoo, Incorporated Executive Summary
The pipeline will be a 42-inch diameter HDPE pipeline about 6,100 feet long from the intake
structure to just above the powerhouse. The pipeline will be laid on grade through the forest for
its entire length, with minimal clearing. It will be at a gentle grade to minimize the pipe
thickness requirement.
The penstock will be aboveground 36-inch diameter steel pipe about 510 feet long. It will
convey water from the downstream end of the pipeline down the hillside to the powerhouse. Just
upstream of the powerhouse, the penstock will branch into two 24-inch pipes leading to the
turbines.
The surge tank will be a 240 feet long section of 6 feet diameter concrete pipe laid on grade
above the junction of the pipeline and penstock. The surge tank will provide passive protection
against pressure surges in the pipeline. It will also assure good frequency control by the Project.
The power plant will be located about 300 feet downstream of a waterfall that serves as a
natural barrier to upstream migration of anadromous fish. The power plant structure will be a
pre-engineered metal building set on a concrete foundation, and will be about 30-feet by 68-feet
in plan dimension, and about 25 feet high. It will house two generating units,'each consisting of
a 700-HP horizontal -shaft Francis turbine, 500-kW synchronous generator, and flywheel. The
power plant will also contain standard utility controls and metering to provide remote unattended
operation. The power plant will discharge through a pipe as far upstream as practical to
minimize the impact to anadromous fish habitat.
The transmission line will include three distinct sections. The initial section will be an
overhead 12.5-kV line from the powerhouse to the port facilities, and will be placed adjacent to
the powerhouse access road (a length of 1.9 miles). The second section will be from the port
facilities to Kootznoowoo Inlet (4.2 miles). It will also be an overhead .line, but it will be
constructed through the forest from the minimum -construction access road described above, with
a clearing width of approximately 25-30 feet. The third section will be a submarine crossing of
Kootznoowoo Inlet to vicinity of the existing float plane dock (4,600 feet).
During construction, there will be two staging areas. One will be located at a large flat area
between the port facilities and the power plant. A construction camp could also be located at that
site if necessary. The second staging area would be located at a flat area about midway between
the power plant and the diversion dam. This staging area will be used primarily for construction
of the diversion dam and pipeline.
2. Generation
The Project will be able to supply all of Angoon's power needs at current load levels over 99%
of the time; generation would need to be supplemented on an average of about 2 days per year.
This percentage would decrease to slightly less than 99% (4 days/year) if loads increase by 50%
and to 97% (10 days/year) if loads increase by 100%. The Project has the potential to generate
about 8.5 million k)Wyear, which is over 4 times the current Angoon annual energy
requirement (2.0 million kWh/year).
The generation amounts indicated above are based on an assumed instream flow requirement of
20 cfs. If resident fish are found in the bypassed reach of Thayer Creek, it is probable that the
state and federal fisheries agencies would want a significantly greater instream flow, which
would decrease the Project generation.
3
HDR Alaska, Inc. ES-4 March 2000
Angoon Hydroelectric Project Feasibility Evaluation Report
Kootznoowoo, Incorporated Executive Summary
wl
3. Estimated Construction Cost
The estimated total cost for the selected arrangement is $8,100,000, as summarized in Table ES-
2. The cost includes about $6,900,000 for direct construction costs and about $1,200,000 for
indirect costs for licensing, design, and construction management. This estimate is based on a
conventional design/bid/build method of Project development. Other methods of development
are possible which could reduce the cost total cost, although at some greater risk or loss of
management control by Kootznoowoo.
The estimated cost of $8,100,000 compares to $9,300,000 previously estimated for Alternative 1,
and $8,500,000 estimated in 1996 by the GH Group for a somewhat similar Project arrangement
and assumptions.
-r
1 F. DEVELOPMENTSCHEDULE
j A preliminary development schedule is shown in Figure ES-3. The development of the Project
will occur in three phases, assuming the development proceeds on a "normal' track. The first
phase is preliminary design and permitting, which includes the current effort as well as future
3 work to obtain the necessary construction approvals from state and federal authorities. The
i
second phase is design and contract bidding, and the final phase is the actual construction.
As can be seen from Figure ES-3, the schedule results in the Project generating power in mid-
2005, which is considered the earliest that the Project could be completed. A significantly longer
schedule can be expected if there is a lack of consensus regarding the desirability of development
of the Project. In the near term, Project development should focus the following activities:
• Determination of the regulatory framework for Project development.
• Pursuit of grant funding and/or low -interest loans to make the Project economical.
W
• Resolution of utility structure issues associated with Project development.
G. ECONOMIC ANALYSIS
The economic analysis contained in the 1998 Angoon Power Supply Study was updated to
reflect the estimated cost of the Project as determined by the current studies. The economic
analysis is basically a comparison of the future cost of power to Angoon citizens with and
without the Project under two different utility structures.
For the first utility structure, it was assumed that power from the Project would be sold to T-
HREA, who would continue to supply electricity to Angoon. With this utility structure, there is
only a small benefit to T-HREA customers from Project construction if nearly all of the
construction cost is grant -funded (i.e., a 2-3% reduction in power costs). Although the benefit is
small, obtaining grant -funding could be easier with this utility structure since the grant would
help more citizens.
For the second utility structure, it was assumed that T-HREA ceases supplying electricity to
Angoon, and Angoon sets up a municipal utility. With this utility structure, there is a substantial
benefit to the community if nearly all of the construction cost is grant -funded. The cost of power
to Angoon citizens initially would be slightly less than the current cost, and would stay relatively
1 constant.
HDR Alaska, Inc. ES-5 March 2000
Angoon Hydroelectric Project
Kootznoowoo, Incorporated
TABLE ES-2
1 COST ESTIMATE SUMMARY FOR
SELECTED PROJECT ARRANGEMENT
Feasibility Evaluation Report
Executive Summary
330
Land and Land Rights
$
_
330.5
Mobilization and Logistics
$
741,000
331
Structures and Improvements
$
543,000
332
Reservoirs, Dams, and Waterways
$
1,587,000
333
Turbines and Generators
$
715,000
334
Accessory Electrical Equipment
$
366,000
335
Miscellaneous Mechanical Equipment
$
110,000
336
Roads and Bridges
$
789,000
353
Substation Equipment and Structures
$
48,000
355
Transmission Line
$
1,173.000
CONTINGENCIES:
Equipment Contingency (Accts. 333,334,335) $ 120,000
Transmission Line Contingency (Accts 353,355) $ 240,000
General Contingency (Accts 330,330.5,331,332,336,350) $ 440.000
PERMITTING AND ENGINEERING:
Licensing/Permitting $ 578,000
Design Engineering $ 400,000
Construction Manatement . ?Sn non
HDR Alaska, Inc. ES-6 March 2000
{
Angoon Hydroelectric Project
Kootznoowoo, Incorporated
Feasibility Evaluation Report
Executive Summary
The analyses confirm that substantial grant funding is necessary for the Project to have a direct
net positive economic benefit. With either assumed utility structure, about 75% of the cost must
be grant -funded for the Project to demonstrate economic feasibility over a 30-year time frame.
This does not consider indirect economic benefits that could accrue due to the electric rate
stability provided by the Project.
Sensitivity analyses were conducted for varying assumptions regarding load growth rates in
Angoon and varying diesel fuel prices. The Project's viability is enhanced by higher load growth
rates and diesel fuel prices with either assumed utility structure.
HDR Alaska, Inc. ES-7 March 2000
i
3
I
I
I
a
w
w
REA RESERVED BY ANILCA
�
~OfEVELOPMfNT
10
EC S06 FOR HYDROELECTRIC
_
�'
BY
1.IK
9f
KOOTZNOOl'
00 INCORPORATED
=
_-T48S
£
Y
wOD
T49S s,l
'
TONGASS NA'T I ON A6'F
k
I
A -'
1_
I
M I R ':A T Y
COY
�TY
ADM I$AX. I S L AN I
PROPOSED
DIVERSI
ATIONAI MONUMENT
(W 1
STRUCTURE
PROPOSED
POWER
CONDUIT
PROPOSED
i .. T49S
POWERHOUSE
T50S
ARC TIC OCEAN
PROPOSED
f OVERLAND
TFOLM dISSION LINE
e
o cacnnon
'i A s �
d
� u
4
jtPSXP
O s PACIFIC OCEAN
I .
;
Ra"POSED.
5
`P
3l3fr1FtRINE AEkE
LOCATION MAP
I` KOOTZNOOWOO #jj
Alaska, Inc.
4
KOOTZNOOWOO INC. MARCH 2O00
ANGOON HYDROELECTRIC PROJECT
Figure
LOCATION AND LAND
OWNERSHIP MAP I ES-1
o�
0
z
0
50
eg
"Ilk
m a
z o
K O
A�
Oo
� 00
Z
y CJ n
� A
2 O
m m
r �
m
m -
� o m
c
—
=�