HomeMy WebLinkAboutVirginia Lake Project Appraisal Report 1977VIRGINIA LAKE PROJECT
APPRAISAL REPORT
THOMAS BAY POWER COMMISSION
PETERSBURG -WRANGELL, ALASKA
PHOENIX. ARIZONA
ORLANDO. FLORIDA
WElLESLEY. MASSACHLISETTS
R. W. BECK AND ASSOCIATES
ENGINEERS AND CONSULTANTS
SEATTLE, WASHINGTON
DENVER. COLORADO
AUGUST 1977
COLUMBUS. NEBRASKA
INDIANAPOLIS, INDIANA
MINNEAPOLIS. MIN.NESOTA
PLANNING
DESIGN
R. W. BECK AND ASSOCIATES
ENGINEERS AND CONSULTANTS
SEATTlE, WASHINGTON
DENVER, COLORADO.
RATES
ANALYSES
EVALUATIONS
MANAGEMENT
200 TOWER BUILDING
SEATTlE, WASHINGTON 98101
TElEPHONE 206-622 -5000
PHOENIX, ARIZONA
ORLANDO, flORIDA.
COLUMBUS, NEBRASKA
WEllESLEY, MASSACHUSETTS
INDIANAPOLIS, INDIANA
FILE NO. WW-1523-HGI-MA
3110
Thomas Bay Power Commission
Post Office Box 758
Wrangell, Alaska 99929
Gentlemen:
August 18, 1977
Subject: Virginia Lake Project
Appraisal Report
We herewith submit the Appraisal Report describing our
investigations and recommendations for the Virginia Lake Project
and alternative hydroelectric projects: Anita-Kunk Lakes, Thoms
Lake and Sunrise Lake.
Our principal findings, conclusions and recommendations
are set forth in the Summary of the report. Details of the site
investigations, supporting data, project development and conclu-
sions are described in subsequent sections of the report.
Respectfully submitted,
R. W. BECK AND ASSOCIATES, INC.
James V. Williamson
Assistant Manager
Western Design Office
J
CERTIFICATE OF ENGINEER
THOMAS BAY POWER COMMISSION
VIRGINIA LAKE PROJECT
APPRAISAL REPORT
The technical material and data contained in this report
were prepared under the supervision and direction of the under-
signed, whose seals, as professional engineers licensed to prac-
tice as such, are affixed below.
, "~""\.."\.
--Of AL '\ _-~t .... 000 ~ ro \'.
,.., .1": o· *0 . v". ;'~... . .. ~ t,
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~ .... ~~ ....... . ~ ~.. DONALD E. BOWES :~ !!.' rj~· .~,., f;~·.o No. 3263-E •• ~~~ ~~.. ..~~". , \ :'/'I •••••••• ~\\. ~ -\\,.~ROfESS\\\~ _--""",,,
Frank-K. Dubar
Principal Engineer
R. W. Beck and Associates, Inc.
Donald E. Bowes
Executive Engineer
R. W. Beck and Associates, Inc.
Section
Number
I
VIRGINIA LAKE PROJECT
APPRAISAL REPORT
TABLE OF CONTENTS
Section and Subsection Title
Letter of Transmittal
Certificate of Engineer
Table of Contents
List of Tables
List of Figures
SUMMARY
INTRODUCTION
l.
2.
3·
Authorization
Scope of Services
a. Compilation and Analysis of
Existing Data on Virginia Lake,
Anita-Kunk Lakes, Thoms Lake
and Sunrise Lake
b. Electrical Load
c. Existing Generation
d. Hydrology and Power Studies
e. Comparison of Alternative Hydro
Sites
f. Geology
g. Project Arrangement
h. Construction Schedule
i. Cost Estimates
j. Economic Feasibility
k. Environmental Concerns
1. Appraisal Report
Background to Present Study
II LOADS AND RESOURCES
1.
2.
3·
4.
5.
General
Historical Load Growth
Power Markets
Projected Loads
Present and Future Resources
a. Petersburg
b. Wrangell
c. Schedule for Future Hydroelectric
Resources
Page
Number
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11-2
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11-3
11-3
11-3
11-4
Section
Number
TABLE OF CONTENTS
(Continued)
Section and Subsection Title
III SITE CONDITIONS
1.
2.
3 .
4.
5.
6 .
General
Virginia Lake Project
Anita-Kunk Lakes Project
Thoms Lake Project
Sunrise Lake Project
Environmental Considerations
a. General
b. Favorable Environmental Effects
c. Possible Adverse Environmental
Effects
d. Historic and Archaeological Sites
IV HYDROLOGY
1. General
2. Virginia Lake Project
a. Streamflows
b. Flows Available for Power
Generation
c. Design Floods
3. Anita-Kunk Lakes Project
a. Streamflows
b. Flows Available for Power
Generation
c. Design Floods
4 . Thoms Lake Project
a. Streamflows
b. Flows Available for Power
Generation
c. Design Floods
5. Sunrise Lake Project
a. Streamflows
b. Flows Available for Power
Generation
c . Design Floods
V DESCRIPTION OF HYDROELECTRIC PROJECT
ALTERNATIVES
1. Virginia Lake Project
a. General
b. Selected Arrangement
2. Anita-Kunk Lakes Project
3. Thoms Lake Project
4. Sunrise Lake Project
Page
Number
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111-2
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111-4
111-5
111-6
111-6
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111-7
111-9
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IV-5
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IV-5
IV-5
IV-5
Iv-6
V-I
V-I
V-I
V-3
V-5
v-6
Section
Number
TABLE OF CONTENTS
(Continued)
Section and Subsection Title
VI POWER OUTPUT AND ECONOMIC COMPARISON
OF HYDROELECTRIC ALTERNATIVES
1.
2.
3 .
4.
Power Output
a. Basis of Studies
b. Method of Operation
c. Power Output
Comparative Construction Costs
a. Basis for Costs
b. Construction Cost Estimate
Cost of Power
a. Annual Costs
b. Cost of Power
Selected Project
VII ESTIMATED CONSTRUCTION COSTS AND SCHEDULE
1.
2.
3.
4 .
General
Basis of Costs
a. Direct Construction Cost
b. Indirect Construction Costs
c. Total Construction Costs
d. Interest During Construction
e. Total Investment Cost
Construction Cost Estimates
Design and Construction Schedule
VIII ECONOMIC ANALYSIS OF VIRGINIA LAKE PROJECT
1.
2.
3 .
4 .
5.
6.
General
Annual Cost of Virginia Lake Project
a. Capital Requirements
b. Fixed Charges on Investment
c. Total Operation and Maintenance
Costs
d. Total Annual Costs
Annual Cost of Alternative Diesel
Installation
Benefit-Cost Ratio and Cost of Power
for First Year
Cost of· Power for First 10 Years
of Operation
Comparison with Thomas Bay Project
Page
Number
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VI-3
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VI-3
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VII-3
VIII-l
VIII-l
VIII-l
VIII-2
VIII-2
VIII-2
VIII-3
VIII-4
VIII-4
VIII-5
Section
Number
TABLE OF CONTENTS
(Continued)
Section and Subsection Title
IX CONCLUSIONS AND RECOMMENDATIONS
X
1.
2.
Conclusions
Recommendations
REFERENCES
APPENDIX A -Reconnaissance Report by
Alan L. O'Neill, Consulting
Geologist
Page
Number
. IX-l
IX-2
X-I
Table
Number
II-l
II-2
II-3
IV-l
IV-2
IV-3
VI-l
VI-2
VI-3
VI-4
VII-l
VII-2
VIII-l
VIII-2
VIII-3
LIST OF TABLES
Title
Petersburg-Wrangell Historical Annual System
Loads
Petersburg-Wrangell Monthly Load Distribution
(In % of Total Annual Load)
Petersburg-Wrangell Existing Generation
Petersburg-Wrangell Average Precipitation
Petersburg-Wrangell Mill Creek Near Wrangell
USGS Gage No.7 -Monthly and Yearly Mean
Discharge
Estimated Reservoir Inflow -cfs
Alternative Hydroelectric Projects
Summary of Preliminary Principal Project
Statistics
Reservoir Operation Studies -Virginia Lake
Summary of Basic Input Data
Hydroelectric Alternatives -Estimated
Construction Cost Summary
Hydroelectric Alternatives Cost of Power
Cost Estimate Summary
Construction Cost Estimates
Virginia Lake and Diesel Alternatives -
Annual Costs
Cost of Alternative Diesel Installation
Ten-Year Cost of Power Analysis (1984-1993)
Figure
Number
1
2
LIST OF FIGURES
Title
Location Map
Virginia Lake Alternative -Peak Load
Growth
3 Virginia Lake Alternative -Energy Load
Growth
4 Virginia Lake Project -Plan and Profile
5 Virginia Lake Project -Sections and Details
6 Anita-Kunk Lakes Project -Plan
7 Thoms Lake Project -Plan
8 Sunrise Lake Project -Plan
9 Design and Construction Schedule
10 Comparison of System Power Costs
SUMMARY
The Thomas Bay Power Commission authorized preparation
of this Appraisal Report to serve as a basis for planning Peters-
burg and Wrangell's future regional electrical generating facili-
ties.
The technical and economic feasibility of hydroelectric
power developments at Virginia Lake, Anita-Kunk Lakes, Thoms Lake
and Sunrise Lake have been studied and the estimated cost of power
from each project compared.
This report summarizes the results of studies and inves-
tigations which have included: reconnaissance of the project sites,
analysis of existing system loads and growth rate, analysis of
hydrology of project drainage areas, conceptual project layouts
for each alternative, power studies, estimate of construction costs
and determination of capital costs for economic comparisons, devel-
opment of a design and construction schedule and a preliminary
environmental evaluation of each project.
The projected energy and peak capacity load growth for
the Petersburg and Wrangell area has been established at 6% an-
nually. In 1976, approximately two-thirds of Petersburg's and
Wrangell's peak capacity was supplied by diesel generation and
more than 60% of its annual energy.
The Virginia Lake Project is located 8 miles east of
Wrangell on the east side of Eastern Passage on Mill Creek. Access
to the project site will be by port facilities located near the
powerhouse at tidewater with a 0.8 mile permanent access road to
the dam. A concrete faced rockfill dam approximately 130 feet
high above streambed will be constructed across Mill Creek 1,300
feet downstream of the outlet from Virginia Lake. An unlined
spillway will be excavated in rock on the right abutment. A 9-
foot diameter steel-lined diversion-power conduit will be con-
structed in the stream channel under the dam from which a 9-foot
Page 2
diameter steel surface penstock will extend 2,450 feet to an above-
ground steel surge tank. The penstock will then continue another
400 feet to a powerhouse at tidewater near the mouth of Mill Creek.
The powerhouse will contain three vertical shaft Francis turbines
with a combined installed capacity of 12,000 kW developed under an
average net head of 174 feet. Approximately 46 miles of 69-kV
single circuit transmission line will extend from the switchyard
at the powerhouse to the cities of Petersburg and Wrangell. The
transmission line contains 12.9 miles of submarine cable.
The Virginia Lake Project with an installed capacity of
12,000 kW will provide 8,900 kW of dependable capacity and
43,750,000 kWh of average annual energy delivered to the load cen-
ters.
Anita-Kunk Lakes Project at installed capacity of 8,600
kW would provide a dependable capacity of 7,930 kW, and 28,100,000
kWh of average annual energy, delivered to the load centers.
Thoms Lake Project at an installed capacity of 7,500 kW
would provide 7,390 kW of dependable capacity and 24,240,000 kWh
of average annual energy, delivered to the load centers.
Sunrise Lake Project at an installed capacity of 4,000
kW would provide a dependable capacity of 3,920 kW and 13,500,000
kWh of average annual energy delivered to the load centers.
The Virginia Lake Project is the only hydroelectric al-
ternative of the four studied that will meet the project load re-
quirements of the Petersburg and Wrangell area at the scheduled
on-line date of September 1983 and in the early years of operation.
Comparative costs for the hydroelectric projects show that the Vir-
ginia Lake Project is by far the most economic of the hydroelec-
tric alternatives.
It is not considered that any of the hydroelectric al-
ternatives would result in major adverse environmental effects.
Page 3
The Virginia Lake Project with financing at 3%, 50-year
term has an estimated Total Investment Cost of $54,173,000 which
results in a Benefit-Cost ratio of 1.02 at the on-line date ofSep-
tember 1983, when compared to the alternative diesel generation.
On a present worth basis, it results in an estimated savings of
$3,850,000 in the cost of power over a ten-year period. For 4%
financing, this savings is reduced to $392,000.
The estimated cost of power from the Phase 1, Thomas Bay
Project, as developed from a previous report, compares closely
with that from Virginia Lake. Thomas Bay would have a larger in-
stalled capacity (20,200 kW) and estimated Total Investment Cost
($81,141,000), and would have more excess energy to dispose of in
the early'years of operation. The Thomas Bay Project does, however,
have the advantage that it would supply the load for a much longer
period than Virginia Lake, and is readily adaptable to economic
second stage development.
Either the Virginia Lake Project or Phase 1, Thomas Bay
Project, is recommended for initial development by the Commission.
The evaluation level investigations of the selected project should
proceed as soon as possible this fall followed by preparation of
the FPC License Application, if the Project is to be on-line by
September 1983.
It is recommended that the Commission attempt to secure
financing for the construction of the selected project for a 50-
year term at an interest rate of 3%, which is the lowest rate pro-
vided for in the Alaska Water Resources Revolving Loan Fund Act.
SECTION I
INTRODUCTION
1. AUTHORIZATION
The work described in this report was authorized by the
Thomas Bay Power Commission (Commission), Wrangell, Alaska by an
Agreement for Engineering Consulting Services dated April 15, 1977.
The Agreement was signed on May 3, 1977.
2. SCOPE OF SERVICES
The Scope of Services involves preparation of an Apprai-
sal Report on the Virginia Lake Hydroelectric Project (Project)
and alternative generation sources to establish the preliminary
feasibility of the Project for initial development to meet the
projected loads and power requirements of Petersburg and Wrangell.
The report would be the basis for financial arrangements for ob-
taining loans through the State of Alaska Water Resources Revolv-
ing Loan Fund. The specific engineering services performed for
appraisal of the Virginia Lake and the alternatives of Anita-Kunk
Lakes, Thoms Lake and Sunrise Lake hydroelectric developments,
the locations of which are shown in Fig. 1, are as follows:
a. Compilation and Analysis of Existing Data
on Virginia Lake, Anita-Kunk Lakes, Thoms
Lake and Sunrise Lake
(1) Previous reports on each project.
(2) Available hydrology information.
(3) Aerial photographs and maps.
(4) Data with respect to project geology.
(5) Environmental data including the results of fish
and wildlife studies.
b. Electrical Load
I-2
Analyze historical electric s~stem loads, load factor
and load growth rate, population and economic data for Petersburg
and Wrangell. Project energy and peak demand through 1990, con-
sistent with base period trends and regional forecasting guide-
lines.
c. Existing Generation
Examine existing facilities at Petersburg and Wrangell
to establish dependable capacity, and firm and secondary energy
available from existing power systems. Review life expectancy of
existing facilities. Stack the available resources, both from a
peak demand and energy viewpoint, on the projected load curves to
arrive at the scheduling for new resources.
d. Hydrology and Power Studies
(1) Preliminary hydrological analyses of the project
drainage basin to determine firm and average runoff and spillway
design floods, for Virginia Lake, Anita and Kunk Lakes, Thorns Lake
and Sunrise Lake.
(2) Estimate firm and average generation from each
project.
e. Comparison of Alternative Hydro Sites
(1) Make reconnaissance level conceptual layouts of
power projects for each of the four sites and develop site costs
to the same broad reconnaissance level.
I-3
(2) Determine broad annual costs for each site from (1)
and develop costs per installed kW and per kWh of energy genera-
ted.
(3) Determine most economic alternative program. for
hydro construction through 1990.
This is expected to confirm earlier analyses that the
Virginia Lake Project will prove to be the most economic and de-
sirable for the initial development in the overall program, and
will definitely establish to the satisfaction of the Commission,
FPC, State and others that the best project has been selected for
first development.
f. Geology
(1) Research all geology reports.
(2) Analyze aerial photos for regional structure and
lineaments.
(3) Make reconnaissance of Virginia Lake Project site
and construction materials borrow areas.
g. Project Arrangement
Prepare preliminary layouts for the Virginia Lake Project
in more detail than in e. above, and perform broad comparisons of
alternative layouts, and tentatively select a project arrangement.
h. Construction Schedule
Prepare construction schedule for project selected ar-
rangement.
1-4
i. Cost Estimates
(1) Prepare preliminary construction cost estimate for
the Project, and alternative diesel generation.
(2) Determine cash flow for Project to arrive at inter-
est during construction and establish total financing requirements.
(3) Determine annual costs for the Project and alterna-
tive diesel generation.
j. Economic Feasibility
Make an economic analysis of the proposed project devel-
opment by comparing costs of power as compared to new diesel gener-
ation.
k. Environmental Concerns
(1) Review available environmental data and identify
potential areas of concern in connection with project construc-
tion.
(2) Meet with State and local agencies, and environ-
mental groups if appropriate, to explore the depth of any such
concerns.
1. Appraisal Report
Prepare an Appraisal Report on the results of the study.
3. BACKGROUND TO PRESENT STUDY
In March 1975, R. W. Beck and Associates, Inc. was autho-
rized by the Thomas Bay Power Commission to investigate the hydro-
electric potential of Cascade Creek to meet the projected power
1-5
requirements of the Petersburg-Wrangell area which culminated in
an Appraisal Report, Thomas Bay Project, dated November 1975. Rec-
ommendations were made in that report to investigate smaller hydro-
electric sites in the area such as Virginia Lake, Thoms Lake and
Anita-Kunk Lakes, that would have a lower initial capital cost and
meet the projected future load requirements more closely.
The Thomas Bay Power Commission decided to investigate
these smaller hydroelectric sites to determine the most economic
project for initial development, and authorized R. W. Beck and As-
sociates, Inc. in May 1977 to perform an appraisal study of ' the
Virginia Lake Project based on reconnaissance level conceptual lay-
outs of these projects, and the alternative Anita-Kunk Lakes, Thoms
Lake and Sunrise Lake sites.
A 200-kW power plant at tidewater on Mill Creek, which
is the outlet from Virginia Lake, was originally constructed un-
der FPC Project No. 1905 for a lumber mill but has since been
abandoned. The City of Wrangell prepared an Application for Pre-
liminary Permit for Virginia Lake Hydroelectric Project on Mill
Creek in 1962 with a powerhouse containing a 3,000-kVA generator.
An Application for Preliminary Permit was also filed by
the City of Wrangell on July 13, 1955 for a proposed hydroelectric
development on Kunk and Anita Creeks. The Preliminary Permit was
issued February 29, 1956 and given FPC Project No. 2189 for a three-
stage development totaling 7,000 kW. The City did not pursue the
Permit.
SECTION II
LOADS AND RESOURCES
1. GENERAL
The power needs in the Petersburg-Wrangell vicinity are
currently served by the City of Petersburg Municipal Power and
Light Department and the City of Wrangell. It is expected that
development of a hydroelectric project will allow these utilities
to reduce their dependence on diesel generation to meet future
loads. This will result in an overall lower cost of energy than
if they rely on diesel generation in the future.
2. HISTORICAL LOAD GROWTH
Historical annual system loads for Petersburg and Wran-
gell for the years 1968 through 1976 are shown in Table II-I. An
analysis of these records shows that the combined service areas
have experienced an average energy growth rate of just over 6% per
year for the period, although load increases have been variable
each year. Annual energy increases have ranged from a low of 1%
to a high of 17% over this period. A decrease in energy at Peters-
burg was experienced in 1975, and a decrease in peak load in Wran-
gell occurred in 1974. However, on the average over the period both
the energy and the peak load increased about 6% per year.
The monthly distribution of the energy needs shows that
larger amounts of generation are required in the late summer, fall
and winter months and the least amounts of generation are required
during the spring and early summer months. An average distribu-
tion over the past five years was adopted as a basis for estima-
ting future monthly load requirements and is shown in Table 11-2.
Power operation studies for the projects being considered were
conducted using this historical load pattern.
11-2
3. POWER MARKETS
A survey of the power market areas was made in previous
studies for the Appraisal Report on the Thomas Bay Project of
November 1975, to aid in recognizing potential load growth areas.
The survey outlined the main users of energy in Petersburg and
Wrangell, which included residential, commercial establishments,
fisheries, canneries, cold-storages and lumber mills. No signifi-
cant changes in the power market have occurred since that time
which would affect current investigations.
4. PROJECTED LOADS
It is difficult to establish a basis for prediction of
long-term load growth with only a short period of historical load
records available; however, predictions made by the Alaska Power
Administration (APA) in July 1976 show a low-range growth rate of
6% and a mid-range growth rate of 7% for southeast Alaska commun-
ities through 1990. Based on historical load records for Peters-
burg and Wrangell which compare favorably with the APA predictions,
a 6% growth rate was selected as a reasonable value for the time
frame considered in this study, and is possibly conservatively low.
In addition, this is consistent with the values developed in the
University of Alaska study in 1976. It is expected that future
load increases could exceed 6% due to block load increases which
might result from conversion to municipal power by the wood pro-
ducts mills in Wrangell, development of other new industries, or
increases in electric heating loads as heating fuel oil increases
in cost.
Forecasted peak loads and energy loads through 1995 for
the combined Petersburg-Wrangell area are shown in Figs. 2 and 3,
respectively.
11-3
5. PRESENT AND FUTURE RESOURCES
a. Petersburg
The present power generation resources for Petersburg
consist of diesel generation plus the Blind Slough Hydroelectric
Project as detailed in Table 11-3.
Future power resources include:
(1) Installation of new diesel units.
(2) Participation in development of regional hydroelec-
tric projects such as Thomas Bay, Virginia Lake, Anita-Kunk Lakes,
Thoms Lake and Sunrise Lake.
b. Wrangell
The present power supply resources for Wrangell are all
diesel generation as shown in Table 11-3.
Future power resources include:
(1) Installation of new diesel units.
(2) Development of local hydroelectric projects such as
Virginia Lake, Anita-Kunk Lakes, Thoms Lake and Sunrise Lake.
(3) Participation in development of the above hydroelec-
tric projects or the Thomas Bay Project as a regional power re-
source.
The total existing combined power generation resources
for Petersburg and Wrangell are 2,100 kW from hydro and 11,450 kW
from diesel generation. Analysis of the existing diesel resources
II-4
indicates that about one-third of the diesel generation should be
retired within the next several years; therefore, only 7,750 kW
of diesel generation is considered to be dependable for the power
studies herein.
The combined Wrangell and Petersburg systems now have
enough hydro and diesel power generation resources to meet the
projected peak load and reserve requirements through 1983. How-
ever, Petersburg will have, within a year or two, to purchase a
new diesel unit to meet forecasted peak load plus reserves require-
ments until the two utility systems are intertied.
c. Schedule for Future Hydroelectric Resources
The Virginia Lake Project would have a nominal installed
capacity of 12,000 kW. The Project would deliver to the load cen-
ters, a dependable capacity of 8,900 kW which has been derived
taking into account the available capacity during the month of
April, the critical month insofar as reservoir stage is concerned,
and the relationship between the April load and the annual peak
load. It would deliver 43,750,000 kWh of average annual energy
to the load centers.
The earliest practical schedule for the Virginia Lake
Project, or any hydroelectric alternative, is considered to be an
on-line date of September 1983. As shown in Figs. 2 and 3, based
on this schedule the Project would essentially meet the system
capacity and energy requirements until mid-1987. This is based on
providing forced-outage reserves equal to the largest single gen-
erating unit, and utilizing the newer diesels for peaking reserves.
This means that a new hydroelectric project should be
on-line by mid-1987 to meet the load. However, it will probably
be more economic to consider reactivating some diesel generation
and to defer completion of the next hydro project, such as Thomas
Bay, until about 1990 as shown in Figs. 2 and 3.
II-5
The generating capabilities of the alternative hydro-
electric developments, Anita-Kunk Lakes, Thoms Lake and SUnrise
Lake, would not meet the system loads at the on-line date of late
1983 as discussed later in the report.
Year
1968
1969
1970
1971
1972
1973
1974
1975
1976
TABLE 11-1
VIRGINIA LAKE PROJECT
PETERSBURG-WRANGELL
HISTORICAL ANNUAL SYSTEM LOADS(l)
Petersburg Wrangell Petersburg-Wrangell
Energy Peak Energy Peak Energy Peak
(MWh) (kW) (MWh) (kW) (MWh) (kW)
12,191 2,400 6,663 1,470 18,854 3,870
12,434 2,600 6,620 1,600 19,054 4,200
13,673 2,650 7,199 1,700 20,872 4,350
16,314 2,950 8,275 2,050 24,589 5,000
16,352 3,000 8,998 2,250 25,350 5,250
16,314 3,000 9,724 2,250 26,038 5,250
18,735 3,500 10,305 2,150 29,040 5,650
16,150 3,250 10,753 2,600 26,903 5,850
19,200 3,444 10,994 2,650 30,194 6,094
(1) -Figures for years 1968 to 1974 obtained from Wrangell
and Petersburg Power System statement to the FPC.
Figures for years 1975 and 1976 obtained from Wrangell
and Petersburg Utilities Generation and Distribution
Reports.
VIRGINIA LAKE PROJECT
PETERSBURG-WRANGELL
MONTHLY LOAD DISTRIBUTION
(In % of Total Annual Load)
January 8.5
February 7.9
March 8.9
April 7.3
May 7.7
June 7.7
July 8.6
August 8.7
September 8.5
October 8.5
November 8.8
December 8.9
Total 100.0
TABLE 11-2
VIRGINIA LAKE PROJECT
PETERSBURG-WRANGELL
EXISTING GENERATION
TABLE 11-3
Type
Nameplate Rating
(Kilowatts)
Petersburg
Diesel 1
Diesel 2
Diesel 3
Blind Slough
Total
Wrangell
Diesel 1
Diesel 2
Diesel 3
Diesel 4
Diesel 5
Diesel 6
Diesel 7
Diesel 8
To ta 1 .................. .
2,100
350
1,250
2,100
5,800 Kilowatts
1,250
1,250
1,250
1,250
500
500
500
1,250
7,750 Kilowatts
SECTION III
SITE CONDITIONS
1. GENERAL
The four potential hydroelectric sites are located in
general in Fig. 1. A field reconnaissance was made of the four
sites including borrow areas, dam sites, powerhouse locations,
penstock alignments, basin diversions and possible transmission
routes. A helicopter assisted in transportation to specific loca-
tions and for aerial observations of proposed facility locations.
A detailed report of the site geology based on the field recon-
naissance, by engineering geologist consultant Alan L. O'Neill,
is included in Appendix A.
The four sites are located in the Wrangell-Revillagigedo
Belt where granites of the Coast Range batholith underlie metamor-
phics at the surface on the mainland and islands. The metamorphics
include interbedded charts, slates, phyllites, marble, greenstone
and schist which strike in a northwesterly direction with a steep
northeasterly dip. This strong northwesterly trend is readily
visible in aerial photos of the Virginia Lake site. The geologic
structure expresses itself as a series of low, parallel ridges.
Glaciation, to some extent, exists at each of the sites
caused by massive ice sheets and valley glaciers fed by the ice
fields. Existing at or near the sites are deep boxlike canyons;
cliffs of polished barren rock and depositional glacial material
in the form of moraines and outwash deposits.
In all four sites there is a scarcity of impervious clay
materials for a clay core zoned type embankment; therefore, a con-
crete faced rockfill dam is the most logical type of structure.
The site conditions observed and investigated at each of the four
sites are discussed briefly in the following.
111-2
2. VIRGINIA LAKE PROJECT
The area immediately surrounding Virginia Lake between
El 100 and El 200 is relatively steep and heavily forested except
for the inlet area where sand and gravel bars are exposed with
open areas covered by muskeg. The outlet from the lake is rela-
tively wide and choked with glacial deposits of silt, sand and
boulders. The sand and gravel from these areas can possibly be
used as a source of concrete aggregates. Accessability to the dam
site from tidewater appears excellent with the access road and
penstock alignment grade at approximately 6% to 10%. See Fig. 4
for project location.
The dam site investigated is located approximately 1,300
feet downstream of the lake outlet and both abutments are covered
with glacial debris. Rock outcrops consisting of dark colored
metasediment ranging from schist to slate were observed upstream
and downstream in the stream channel as well as above the glacial
debris cover at the site. Future investigations will determine
the extent of debris since a cutoff into bedrock will be neces-
sary for the concrete upstream face. Curtain grouting below the
cutoff will be required.
Rock for the proposed rockfill darn will corne from the
spillway and a quarry cut into the right abutment. A concrete
lined spillway chute is not considered necessary.
Diversion of Mill Creek during construction can be easily
handled since the stream width at this point is moderately wide.
A cut and cover steel-lined concrete conduit section founded on
bedrock beneath the dam can be used for diversion, and later as
part of the power conduit.
The powerhouse site which is located to the left of the
mouth of Mill Creek at tidewater, has rock exposed and a good
111-3
foundation can be developed. A good port site can also be devel-
oped in the area.
3. AN1TA-KUNK LAKES PROJECT
The area immediately surrounding Anita Lake up to El 1420
is relatively steep with a heavy forest cover along the northern
shoreline. Access to the darn site and the penstock is relatively
steep; in Anita Creek approximately 25% grades would be experienced
which would make access for construction difficult. No other spe-
cial problems were observed (see Fig. 6 for project location).
The darn site is located at the outlet to the lake where
the foundation rock is granitic and is exposed on the left abut-
ment. The right abutment is covered with a steep talus slope which
has fallen from above which would have to be removed as it, in all
probability, consists of silty, clayey soil mixed with rock debris.
The left abutment and stream channel would also have to be exca-
vated to bedrock. Grouting of the foundation would be required.
Rock for the darn would corne from a spillway cut in the
left abutment and from a quarry located in the same area. A con-
crete lined spillway would not be required in this granitic rock.
A source of concrete aggregate for the upstream concrete face was
not observed in the project area and would have to be either manu-
factured at the site or imported.
The powerhouse would be located on the south side of
Kunk Lake against a steep hillside where rock outcrops were ob-
served. Foundation in this area should be in granitic type rock.
Protection of the powerhouse from falling rock would be required.
The darn site at Kunk Lake is located just downstream of
the outlet. Fine-grained igneous rock outcrops were observed in
the left abutment. The right abutment is covered more by overbur-
den which would have to be removed. Rock for the darn would corne
111-4
from the spillway cut in the left abutment and from a quarry in
the same area. The spillway chute would not require lining in
this rock formation. Excavation into bedrock for the contact of
the concrete upstream face would be required as would grouting of
the foundation.
Access to the dam site from tidewater appears reasonable
with maximum grades of about 15%. The power conduit would be a
tunnel at the upper end and then penstock loading to the plant at
tidewater. The tunnel would pass through a competent granitic rock
ridge to the east of the dam.
The powerhouse would be located to the right of the stream
mouth and exposed bedrock was observed along the shoreline at tide-
water. No special foundation problems are anticipated. A port
facility could be constructed in the general area of the powerhouse.
4. THOMS LAKE PROJECT
Figure 7 shows the project location. The general area
surrounding the existing Thoms Lake up to El 200 is only moderately
forested with numerous open areas consisting of muskeg. All three
dam sites are covered with muskeg and no in-place rock could be
located or evidence seen to estimate depth to bedrock. The pres-
ence of numerous small rounded hills in the area similar to Kame-
like glacial structures suggests that the whole area has a cover-
ing of glacial debris over bedrock.
The three dams would be concrete faced rockfill structures
since no impervious material was found and a rock quarry could be
developed within two miles of the proposed sites. Concrete aggre-
gate for the concrete-lined upstream face is assumed to be avail-
able within the glacial material surrounding the lake. Access to
the sites would be by extending the existing road from Wrangell.
111-5
A power tunnel mayor may not be feasible depending on
depth of glacial moraine in the area. In the vicinity of the
powerhouse at tidewater, bedrock was observed, although the plant
foundation would have to be placed on granular materials.
5. SUNRISE LAKE PROJECT
Figure 8 shows the project location. The area surround-
ing Sunrise Lake up to EI 2000 is sparsely forested and consists
mostly of brush and a thin cover of muskeg. Granodiorite rock
outcrops through the snow cover were observed. A rockfill dam with
concrete face would be placed at the outlet to the lake at EI 2000.
Rock could be quarried from either abutment for embankment mate-
rial. The outlet from the lake falls abruptly over a precipitous
slope for several hundred feet. Access to the area can only be
accomplished by helicopter.
The dam would be founded on sound rock and there ex-
ists a natural depression in the left abutment which could serve
as a spillway. Grouting of the foundation is anticipated. The
construction season would be very short at this elevation.
The penstock would be located on a precipitous slope and
would require anchorage to the rock and rock bolts to secure the
rock slope during construction and expected loosening later due to
frost action.
The powerhouse site at EI 300 would be located at the
head of a relatively flat sloping valley. Access to the power-
house appears excellent with a relatively flat grade from tide-
water where a port could be constructed.
111-6
6. ENVIRONMENTAL CONSIDERATIONS
a. General
Development in the near future of hydroelectric genera-
tion for the Petersburg-Wrangell area is necessary to shift away
from the use of expensive nonrenewable resources (diesel fuel) to
a more reliable long-term energy resource. The resulting construc-
tion activity will necessarily have temporary adverse effects on
the environment; however, with proper considerations during design,
construction and operation, long-term harmful effects will not be
significant.
At this level of investigation with only limited review
of environmental considerations, it is not possible to positively
identify or quantify environmental effects, adverse or favorable.
However, based on recent assessments and previous studies of simi-
lar projects in southeast Alaska, it is possible to identify typi-
cal environmental effects of hydroelectric projects and identify
areas of possible concern for future study. On this basis, the
following listing and brief discussion of environmental effects
were developed.
b. Favorable Environmental Effects
(1) Petersburg and Wrangell will be gaining an addi-
tional source of power generation critical to meeting and stabil-
izing future expansion and growth needs.
(2) The local economy will experience a boost during the
construction period. An estimated labor force of from 100 to 200
will be required for project construction which will reduce any
local level of unemployment during that period.
111-7
c. Possible Adverse Environmental Effects
(1) Adverse impacts on existing fish habitats frequently
result from hydroelectric projects with their required impoundment
and regulated discharges from the reservoirs. Water quality par-
ameters of particular concern are temperature, sedimentation and
streambed stability, all of which are important to fish habitat.
Information received from the State of Alaska Department of Fish
and Game regarding fish assessment of the projects under consider-
ation states:
"(a) Thoms Creek
This creek supports excellent populations of pink, chum,
sockeye, and coho salmon; cutthroat and steelhead trout, and Dolly
Varden char. Most of the pink and chum salmon spawn in lower Thoms
Creek, while the other species spawn and rear in the upper reaches
of Thoms Creek, in Thoms Lake and tributary streams to the lake.
In addition to the recreational and commercially important spe-
cies, three-spined sticklebacks and cottids are also present.
There is a Forest Service recreational cabin located on
the lake and a well developed trail provides access from Zimovia
Strait. Thoms Lake and Creek provide excellent recreational fish-
ing opportunities for steelhead and cutthroat trout, and Dolly
Varden char. According to Forest Service records, the Thoms Lake
cabin has averaged 140 visitor days per year for the past eight
years.
(b) Kunk Creek
This system supports runs of pink, chum, sockeye and coho
salmon, steelhead and cutthroat trout, and Dolly Varden char. There
is a Forest Service cabin on the lake and a maintained trail pro-
vides access from saltwater. The area receives moderate recrea-
tional fishing pressure primarily from Wrangell and Petersburg
residents.
111-8
(c) Mill Creek
This creek drains Virginia Lake and supports populations
of pink, chum, sockeye and possibly coho salmon; steelhead and
cutthroat trout; and Dolly Varden char. The sockeye populations
are unique in that they are small and can get over the falls on
Mill Creek where larger fish cannot. There is a Forest Service
cabin on Virginia Lake and a maintained trail provides access from
saltwater. There is light angler use of the lake, with most fish-
ing in Mill Creek occurring at tidewater.
(d) Sunrise Lake
Little is known about this system of three small lakes
on Woronkofski Island. There is a barrier falls on the outlet
stream. The lakes can be reached by a two-mile trail from salt-
water. During surveys conducted in 1969, no fish were reported in
the lakes. Pink, chum and coho salmon may possibly utilize the
outlet stream for spawning. Of the four areas, this area would
have the least recreational potential."
(2) The major effect on wildlife habitat in the project
sites would be the loss of food and cover in localized areas. For
example, for many wildlife species in southeast Alaska, including
deer, bear, waterfowl and mountain goats, along with the bald eagle,
the lowland lake and stream areas and beach fringe areas are an es-
sential part of their territory. Construction and use of project
features such as powerhouses, transmission lines and access roads
would disrupt this type of habitat. The most prominent species that
could be affected by the projects under consideration is the black-
tailed deer that use lowland waterway areas as winter range. The
extent of the impact of any of the projects on eagle nesting areas
was not possible to evaluate since nesting sites for these areas
have not been identified. The U.S. Fish and Wildlife Service,
111-9
Eagle Management Division, this year is in the process of survey-
ing southeast Alaska for eagle nesting areas and information
should be forthcoming, on the project sites. The U.S. Fish and
Wildlife Service in the summary of their 1958 report on the fish
and wildlife resources of the Virginia Lake Basin state:
"The survey work described herein indicates that
Virginia Lake Basin near Wrangell, Alaska, possesses
valuable wildlife and fishery resources. It supports
big game hunting for bear, deer, mountain goat and,
to a limited extent, moose. Anglers fly into this lake
via charter aircraft to enjoy the cutthroat trout fish-
ing it offers. The lake supports a significant spawn-
ing population of red salmon and its waters serve as
nursery grounds for the smolts of this species.
Additional fieldwork will be required to determine
project effects upon the fish and wildlife resources."
(3) A hydroelectric power project would have some ad-
verse visual impacts resulting from materials excavation and dis-
posal required for construction of the access roads, dam, power-
house, power conduit and transmission line.
(4) Construction would require movement of heavy equip-
ment and materials in and around the project site causing some
erosion and stream sedimentation. Temporary effects of equipment
operation and blasting would include high noise levels at times,
air quality reduction caused by machinery exhaust and burning of
wastes and possible disturbance of local wildlife populations.
d. Historic and Archaeological Sites
There are several historic and archaeological sites listed
in the Alaska Archaeological/Historical Survey record close to the
sites. Most of the sites are located on Wrangell Island close to
and within the City limits and present no problem to the projects.
SECTION IV
HYDROLOGY
1. GENERAL
The general weather patterns which prevail in the Peters-
burg-Wrangell area are typical of much of southeast Alaska. Year-
round southerly winds due to fall and winter low pressure systems
in the north Pacific, and spring and summer low pressure over the
heated interior, tend to bring warm, moist air in from the ocean,
causing milder temperatures than would normally be expected at
such a northerly latitude. These warm winds are cooled in their
ascent of mountain slopes causing precipitation. The resulting
precipitation varies greatly with degree of air saturation, air
temperature and localized orographic effects. Extreme variations
occur within a few miles distance; however, the major result is
that much heavier precipitation and higher runoffs occur on the
upper portions of the drainage basins where temperatures are con-
siderably lower than those recorded near sea level.
The weather stations at Petersburg and Wrangell are near
sea level at El 50 and El 37 respectively, with both stations re-
cording an average annual temperature of about 45°F. The average
monthly and mean annual precipitation recorded at these stations
based on historical records through 1974 is shown in Table IV-I.
Based on recorded runoffs on streams in the Petersburg-Wrangell
area, it is estimated that the average annual precipitation on the
basins of the sites range from 115 to 175 inches per year.
2. VIRGINIA LAKE PROJECT
a. Streamflows
Gaged streamflows are available for Mill Creek near
Wrangell, United States Geological Survey (USGS) Gage No. 7 from
IV-2
July 1915 through August 1928 and a summary of these flows is shown
in Table IV-2. Records are intermittent over this period and the
longest period of continuous record is 2 years, 1916 and 1917, with
gaged flows of 410 and 413 cfs respectively. The precipitation in
southeast Alaska during these two years was slightly below normal.
A higher average annual discharge of 441 cfs was determined by av-
eraging the monthly means of the 49 discontinuous months of re-
corded flows. It is not possible to reach an accurate conclusion
as to either the volume or seasonal distribution of runoff into
Virginia Lake based solely on this intermittent information.
In order to make a reliable estimate of average annual
runoff into Virginia Lake, a mathematical model was developed to
establish a relationship between mean drainage basin elevation and
average annual basin runoff. A correlation was made using recorded
annual flows for four basins in the vicinity as follows:
Drainage Basin
Big Creek
Harding River
Tyee Creek
Cascade Creek
Drainage Area
(Sq. Mi.)
11.2
67.4
16.1
23.0
Average
Annual Runoff
(cfsm)
7.8
10.9
10.9
11.0
Mean Basin
Elevation
(Feet)
680
2,475
2,675
2,935
Using the above relationships and a mean basin elevation of 1840
for Virginia Lake, the average runoff was estimated to be 10.2 cfs
per square mile, or 414 cfs for the 40.6 square mile basin. This
figure checked very closely with the two years of recorded flows
on Mill Creek which averaged 412 cfs for slightly below average
years of runoff. In order to estimate runoffs for a continuous
period and to establish a monthly flow distribution, a correlation
was made with nearby Harding River near Wrangell, USGS Gage No. 220.
Recorded flows from October 1951 through September 1974, a period
of 23 years, show that the average runoff at the gage was 735 cfs.
IV-3
The estimated average annual runoff from the Virginia Lake Basin
is approximately 56% (414/735) of this figure. A 23-year contin-
uous period of synthesized flow data was obtained (using this ra-
tio) from 1951 through 1974, and is shown in Table IV-3. The re-
sulting flows are slightly less than would have been prediqted by
using the straight drainage area ratio of 60%, due to the fact that
higher elevation basins generally record higher runoffs per square
mile than lower elevation basins due to orographic effects.
b. Flows Available for Power Generation
The streamflows developed in the previous section were
used for the power studies in Section VI for this Project. The
average annual runoff used was 414 cfs.
c. Design Floods
A Probable Maximum Flood (PMF) hydro graph was developed
for the Virginia Lake drainage basin using Clark's Method for unit
hydrograph determination. A 24-hour Probable Maximum Precipita-
tion (PMP) was estimated for this area based on information given
in U.S. Weather Bureau Technical Paper No. 47, and a snowmelt con-
tribution of 5.3 inches was added. The PMF determined by this
method has a peak inflow of 65,300 cfs and the total volume over
the base flow is 42,700 acre-feet.
3. ANITA-KUNK LAKES PROJECT
a. Streamflows
Since no recorded streamflows are available for these
lakes, average annual runoffs for the contributing portions of the
Anita Lake and Kunk Lake drainage hasins were estimated using
the runoff vs. elevation relationship established for the Virginia
Lake Project. The mean basin elevation of Anita Lake was found
Iv-4
to be 2200 feet for the 2.5 square mile area surrounding the lakes,
and the average annual runoff was estimated to be 10.76 cfs per
square mile, or 27 cfs. The 3.5 square mile Kunk Lake drainage
area has a mean elevation of 940 feet and an estimated average an-
nual runoff of 8.45 cfs per square mile, or 30 cfs. Interbasin
transfers are estimated at approximately 17 cfs based on diversion
of about 2 square miles of additional area into the Kunk Lake Basin.
b. Flows Available for Power Generation
Monthly power operation studies were not performed for
this Project. Project generation is based on the estimated aver-
age annual flows, and an average operating head as discussed in
Section VI, and based on an assumed method of operation of the
interbasin diversions.
c. Design Floods
A preliminary PMF hydro graph was developed for the Kunk
Lake dam site based on the contributing drainages. The peak in-
flow was estimated to be 9,400 cfs and the total volume above base
flows was estimated to be 4,600 acre-feet.
4. THOMS LAKE PROJECT
a. Streamflows
No historical streamflow records have been maintained at
Thoms Lake. Estimates of average annual runoff at the dam site
were based on nearby drainage basins having similar characteristics
and the runoff vs. elevation relationship established for the Vir-
ginia Lake Project. Thoms Lake is a lower-elevation basin with a
mean elevation of 900 feet for its 19 square mile area above the
dam site. Average annual runoff is estimated to be 8.3 cfs per
IV-5
square mile, or 158 cfs. This is slightly higher than the recor-
ded 7.8 cfs per square mile runoff at Big Creek near Point Baker,
primarily due to difference in basin elevations.
b. Flows Available for Power Generation
No estimates of monthly flows were developed for this
study and detailed reservoir operation studies were not conducted.
Project generation was based on the estimated average annual in-
flows to the Thoms Lake Reservoir, and an estimated average oper-
ating head, as discussed in Section VI.
c. Design Floods
A preliminary PMF hydro graph was developed for the Thoms
Lake drainage area for use in flood routing and spillway slzlng.
The peak inflow was estimated to be 18,000 cfs and the total vol-
ume above base flows was estimated to be 18,000 acre-feet.
5. SUNRISE LAKE PROJECT
a. Streamflows
Since no recorded streamflows are available for Sunrise
Lake, average annual runoff at the dam site was estimated using
the runoff vs. elevation relationships previously established.
Based on a mean basin elevation of 2300 feet for the 1.16 square
mile drainage basin, average annual runoff at the dam site was es-
timated to be 13 cfs per square mile or 15 cfs. No monthly pat-
tern of runoff was determined for this study.
b. Flows Available for Power Generation
Detailed reservoir operation studies were not conducted
at this time. Project generation was estimated based on estimated
Iv-6
average annual inflows to Sunrise Lake, and the available head to
a powerhouse at EI 300, as discussed in Section VI.
c. Design Floods
No PMF determination was made for this study, since a
large natural spillway saddle exists along the left abutment which
could handle any flood flows from this small drainage area.
Month
January
February
March
April
May
June
July
August
September
October
November
December
Mean Annual
VIRGINIA LAKE PROJECT
PETERSBURG-WRANGELL
AVERAGE PRECIPITATION
Precipitation (Inches)
Petersburg Wrangell
9.4 7.2
7.6 6.4
7.0 5.5
7.0 4.9
6.2 4.2
4.8 3.9
5.1 4.8
7.6 6.0
11.6 8.5
17.3 12.5
10.6 10.0
10.6 8.0
104.8 81. 9
TABLE IV-l
VIRGINIA LAKE PROJECT
MILL CREEK NEAR WRANGELL
USGS GAGE NO. 7(1)
MONTHLY AND YEARLY MEAN DISCHARGE (cfs)
Water « Yearly
Year Oct. Nov. Dec. Jan. Feb. Mar. ~ May June July ~ Sept. Average
1915 442 645 639
1916 672 207 175 39.0 131 63.5 245 402 806 808 728 649 410
1917 674 248 98.9 89.7 231 51. 2 137 524 667 723 789 725 413
1923 618 672
1924 1,070 890 750 730 831
1925 607 446 182 57.4 80 140 220 851 797 851
1927 841 711 568 845
1928 934 809 821 438
(1) -Location: A quarter of a mile downstream from Virginia Lake, half a mile upstream from
mouth, and seven miles east of Wrangell.
VIRGINIA LAKE PROJECT
ESTIMATED RESERVOIR INFLOW -CFS
YEAR OCT NOV DEC JAN rEe MAR APR MAY JuN JUL AUG SEP AVERAGE ••........ . •••... ....... ....... . ...... ....... ....... ....... ....... . ...... . _ ..... ....... •.•..• -. ......
1951-52 347 176 141 51 51 56 198 536 733 885 718 775 389
1952-53 751 274 111 58 62 83 183 704 763 668 487 650 400
1953-54 766 241 167 66 369 61 51 379 750 705 452 490 375
1954-55 531 460 273 132 115 82 141 363 745 799 918 655 434
1955-56 445 230 68 37 34 37 170 764 629 732 933 448 377
1956-57 435 312 325 76 51 45 150 576 837 715 469 571 380
1957-58 401 367 137 222 84 94 252 602 736 570 706 377 379
1958-59 9B5 272 211 84 79 97 192 529 855 1,017 632 517 456
1959-60 745 270 442 145 124 127 277 516 737 889 753 616 470
1960-61 939 269 257 159 189 139 274 499 837 741 7b9 600 473
1961-62 1,212 238 94 411 158 176 269 463 825 797 6b8 747 505
1962-63 556 371 509 324 347 114 171 466 689 671 397 887 459
1963-64 623 152 215 132 147 74 166 413 1,041 946 763 415 424
1964-65 630 243 169 . 94 65 55 220 399 776 789 474 286 350
1965-66 837 136 88 47 38 160 198 483 771 803 744 744 421
1966-67 531 259 76 60 97 56 89 494 821 675 744 981 407
1967-68 538 340 120 68 246 204 142 500 603 709 427 952 404
1968 -69 394 266 70 29 26 31 182 631 926 '57 729 437 373
1969-70 344 705 252 66 172 134 148 416 937 756 759 757 454
1970-71 511 328 130 83 47 45 121 430 816 713 736 514 373
1971-72 407 203 95 55 108 194 79 562 868 1,058 876 626 428
1972-7J 347 180 72 125 78 i3 161 498 744 756 759 663 371
1973-74 382 100 230 63 179 86 :215 470 668 845 710 723 389 ..•...••.• ....... •...... . ...... .-..... ....... .._--.-....... _.-.... ....... _.-.. _---_ .... ..---.-.......
AVERAGE 594 278 185 113 125 97 176 508 787 782 679 627 413
2J-YEAR AVERAGE • Ul
Drainage Area = 40.6 Square Miles
t-3 :z::,
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SECTION V
DESCRIPTION OF HYDROELECTRIC PROJECT ALTERNATIVES
1. VIRGINIA LAKE PROJECT
a. General
Virginia Lake is located on the mainland approximately
8 miles east of Wrangell and lies within a heavily-forested basin
along the east side of Eastern Passage. The drainage basin~ which
is the largest of any of the projects under consideration in this
study, encompasses an estimated 40 square miles above the dam site.
The basin rises from El 85 at the proposed dam site to elevations
of 4000 and 5000 feet at its upper reaches.
Preliminary layouts and cost estimates were prepared for
two alternative dams with the dam crests at El 190 and El 210 for
the Virginia Lake Project. The alternatives involved construc-
tion of a concrete-faced rockfill dam about 1/4 mile downstream
from the outlet of Virginia Lake on Mill Creek, with a surface
steel penstock leading to a powerhouse near tidewater on Eastern
Passage.
b. Selected Arrangement
The selected arrangement for development of the Project
is shown in Figs. 4 and 5. It will consist of a 130-foot high
rockfill dam with crest at El 210, constructed approximately 1,300
feet downstream of the outlet of Virginia Lake. The upstream slope
of the dam will have a concrete facing. A 200-foot wide open
channel spillway will be excavated in rock on the right abutment
and an ungated concrete overflow weir will maintain the active
storage capacity of 91,700 acre-feet below the normal maximum
reservoir pool El 200.
V-2
During construction of the dam, the power conduit, lo-
cated near the stream channel along with a small cofferdam up-
stream, would be used to divert streamflows. It will extend from
an intake structure at the toe of the upstream face of the dam to
a surface powerhouse at tidewater south of the mouth of Mill-Creek
on Eastern Passage. The conduit will consist of a 9-foot diameter
steel penstock approximately 2,450 feet long connecting to an above-
ground surge tank at El 100. From the surge tank the penstock
will extend another 400 feet and will branch to each unit before
entering the powerhouse.
The surface powerhouse will contain three vertical shaft
Francis turbines with a nominal total installed capacity of 12,000
kW corresponding to a discharge of 1,070 cfs under an average gross
head of 163 feet. Approximately 46 miles of 69-kV single circuit
transmission line will extend from the switchyard at the powerhouse
to connect to existing distribution systems in Petersburg and
Wrangell (see Fig. 1). The transmission line requires approxi-
mately 1.0 miles overland near the plant, 1.5 miles of underwater
cable across Eastern Passage from the powerhouse, connecting to
7.0 miles of overhead transmission along the western side of Wran-
gell Island to the tip of the island. From there approximately
11.4 miles of underwater cable crossing is required between Wran-
gell Island and Mitkoff Island, connecting to approximately 25
miles of overhead transmission line constructed along Mitkoff
Highway to the City of Petersburg. About 3.5 miles of construc-
tion access roads would be required to construct a portion of the
overhead transmission line on Wrangell Island.
Permanent access to the project site would be provided
by port facilities constructed near the outlet of Mill Creek adja-
cent to the powerhouse on Eastern Passage, with approximately 0.8
miles of permanent access road from the port and powerhouse to the
dam.
V-3
2. ANITA-KUNK LAKES PROJECT
The Anita Lake and Kunk Lake drainage basins are located
approximately 14 miles southwest of Wrangell on the northern tip
of Etolin Island (Fig. 1 shows the general location). Two adja-
cent drainage basins are diverted and utilized with the proposed
project arrangement to increase the usable runoff for power gener-
ation at this site, making a total drainage area of 8 square miles.
Development of a project at this site involves construc-
tion of two dams, two power conduits and powerhouses, plus diver-
sion dams and ditches for interbasin transfers of water. The proj-
ect arrangement is shown in Fig. 6.
A 60-foot high concrete-faced rockfill dam with crest
at El 1430 is required at the outlet of Anita Lake in order to
raise the normal water surface to El 1420, to regulate the 2.5
square mile drainage basin above the lake. An open channel spill-
way would be provided in the left abutment. The power conduit~ a
30-inch diameter surface steel penstock~ would extend approximately
6,300-feet from the dam, along the left side of Anita Creek to a
surface powerhouse on the southern shore of Kunk Lake. The power-
house would contain a single generating unit with a nominal instal-
led capacity of 4,300 kW, operating under a net head of 1~007 feet.
Kunk Lake would be raised to a normal water surface of
El 350 by a concrete-faced rockfill dam at its outlet. An open-
channel spillway would be excavated in rock on the left abutment.
The power conduit would extend from an intake structure~ approxi-
mately 2,750 feet to a surface powerhouse located at tidewater on
Zimovia Strait. The conduit would consist of a 7-foot diameter
concrete-lined tunnel approximately 1,600 feet long to a portal
about 800 feet upstream of the powerhouse, and a 4-foot diameter
steel penstock to the powerhouse. The powerhouse contains a single
generating unit with a nominal installed capacity of 4,300 kW, op-
erating under a net head of 310 feet.
V-4
In addition to the above project features, a small di-
version dam is required about 1,200 feet upstream of the bend on
Anita Creek and a 1,700-foot long ditch to divert streamflows in-
to Kunk Lake. Another diversion ditch, approximately 2,500 feet
long is required to divert streamflows from the basin to the north
of Kunk Lake, to a point upstream of the dam at the lake outlet.
It is estimated that this latter diversion will provide an addi-
tional 15 cfs of average annual inflow to the Kunk Lake Reservoir.
An estimated 3.5 square miles of drainage area above the dam site
drains directly into Kunk Lake, an additional 0.4 square miles
from the diversion of Anita Creek flows, and 1.6 square miles by
diversion of the basin to the north of Kunk Lake for a total of
approximately 8 square miles of drainage area.
Approximately 1.6 miles of 69-kV transmission line would
connect the two powerhouses on this Project, and from the lower
powerhouse an additional 52.8 miles would be required to connect
with existing distribution systems at Petersburg and Wrangell.
This transmission line includes approximately 1.1 miles of under-
water cable from the lower powerhouse across Zimovia Strait, 3.6
miles (including access road) north along the eastern side of the
Strait, to a point about 10.5 miles south of Wrangell, where it
would follow the alignment of the existing road into Wrangell.
The portion from Wrangell to Petersburg involves 37.6 miles total
(same as for the Virginia Lake Project) including approximately
1.2 miles of overhead transmission from Wrangell to the tip of
Wrangell Island, 11.4 miles of submarine cable and 25 miles of
overhead transmission to Petersburg.
Access to the project site would be provided by a per-
manent port facility constructed near the lower powerhouse on
Zimovia Strait. Approximately 0.6 mile of access road would be
constructed from the port to the dam on Kunk Lake, plus 2.5 miles
of additional access road to the Anita Lake dam and powerhouse
site.
V-5
3. THOMS LAKE PROJECT
Thoms Lake is located on Wrangell Island approximately
17 miles south of Wrangell, situated within a drainage basin which
drains to the southeast into Zimovia Strait (Fig. 1 shows the gen-
eral location). Approximately 8.1 square miles of area surrounding
Thoms Lake drains directly into the lake and additional drainages
of 6.4 and 4.5 square miles would be diverted from basins lying to
the north and east respectively.
The Thoms Lake project arrangement is shown in Fig. 7.
Three small concrete-faced rockfill dams would be required to raise
the water level of Thoms Lake to El 300. The reservoir level would
be controlled by an open-channel spillway constructed on the right
abutment of the east dam, which would discharge into Thoms Creek
to the southeast. Diversion dams on creeks to the north and east
of Thoms Lake along with ditches approximately 3.3 and 2.0 miles
long would divert runoff from the two basins, to Thoms Lake.
A power conduit would extend approximately 4,800 feet
from an intake located on the right abutment of the south dam to
a surface powerhouse near tidewater on Zimovia Strait. It would
consist of approximately 4,200 feet of 7-foot diameter tunnel to
a portal about 600-feet upstream of the powerhouse, where it con-
nects to a 5-foot diameter surface steel penstock. A surge tank
located approximately 1,700-feet upstream of the powerhouse is re-
quired. The powerhouse would contain two generating units with a
total nominal installed capacity of 7,500 kW, operating under a
net head of 274 feet.
The project would require approximately 57.7 miles of
69-kV transmission line to connect with the distribution systems
in Petersburg and Wrangell. This would involve construction of
approximately 9.6 miles (including access road) from the powerhouse
north along Zimovia Strait, to a point about 10.5 miles south of
v-6
Wrangell where it would follow the alignment of an existing road
into Wrangell. The portion from Wrangell to Petersburg would be
the same as required for the Virginia Lake Project, involving ap-
proximately 11.4 miles of submarine cable and 26.2 miles of over-
head transmission line.
Access to the project site would be accomplished by ex-
tending the existing road from Wrangell to Pat Creek southward
along Zimovia Strait approximately 9.6 miles. An additional 3.2
miles of site access roads would be required from the powerhouse
location to various project facilities.
4. SUNRISE LAKE PROJECT
The Sunrise Lake project site is located at the center
of Woronkofski Island approximately 6 miles southwest of Wrangell
(Fig. 1 shows the general location). The drainage basin lies
above the 2,000-foot level and ranges to peak elevations of 2500
to 3200 feet at its perimeter. Three small lakes including Sun-
rise are contained within the basin. The project arrangement is
shown in Fig. 8.
A 40-foot high concrete-face rockfill dam to crest El
2010 at the outlet of Sunrise Lake would raise the existing lake
to a normal maximum water surface El 2000 to permit regulating run-
off from the small 1.16-square mile drainage basin. A concrete
weir section in a natural channel in the left abutment would serve
as a spillway. An 18-inch diameter surface steel penstock approx-
imately 3,400 feet long would connect to a powerhouse located along
Sunrise Creek at El 300. The powerhouse would contain a single
generating unit with a nominal installed capacity of 4,000 kW op-
erating under an average net head of 1,608 feet.
Approximately 46.3 miles of transmission would be required
to deliver energy to Petersburg and Wrangell distribution systems.
V-7
From the powerhouse approximately 3.6 miles of new overhead trans-
mission line would extend to the eastern shore of Woronkofski Is-
land, connecting to 2.1 miles of underwater cable across Zimovia
Strait to Wrangell Island. An additional 3.0 miles of overhead
transmission line would follow the alignment of the existing road
north to Wrangell. The portion from Wrangell to Petersburg (same
as for Virginia Lake Project) would involve approximately 11.4
miles of underwater cable and 26.2 miles of overhead transmission
line.
Site access would be provided by port facilities con-
structed on the western side of the Island near the mouth of Sun-
rise Creek, and approximately 1.2 miles of permanent access road
would be required from the port to the powerhouse location.
SECTION VI
POWER OUTPUT AND ECONOMIC COMPARISON
OF HYDROELECTRIC ALTERNATIVES
1. POWER OUTPUT
a. Basis of Studies
For the Virginia Lake Project monthly power operation
studies were performed utilizing reservoir inflows shown in Table
IV-3, and the monthly load distribution is discussed in Section II
to represent typical future system monthly load patterns.
For the other hydroelectric alternatives, the estimated
average annual energy from each project was developed based on
estimated average reservoir elevation and the average annual run-
off at the dam site adjusted by judgment to allow for less than
100% reservoir regulation. The average head used in this analysis
was generally derived from the results of the Virginia Lake opera-
tion studies. The dependable capacity was based on the project
output at minimum reservoir elevation. A summary of the prelimi-
nary principal project statistics for the alternatives is shown
in Table VI-I.
b. Method of Operation
The operation studies for Virginia Lake simulate a month-
by-month operation following a rule curve such that water is with-
drawn from storage to generate required energy each month. During
periods when inflows are high, the reservoir would be maintained
at or near the normal pool; during low flow periods, the reservoir
would be drawn down to the required level to meet firm generation
requirements each month. Normally, the reservoir would be opera-
ted in the upper third of the drawdown range so that the capacity
VI-2
available in any average year would be much higher than the capac-
ity available during low runoff years. Dependable capacity is
that available during the second lowest reservoir level over the
period of the study (El 114). This occurs during the month of
April which is not the peak load month for the system. The mini-
mum reservoir elevations during the peak loads in the summer and
winter are much higher.
Results of the monthly operation studies for Virginia
Lake are shown in Table VI-2 (5 sheets), including the energy gen-
erated, reservoir elevation and discharge from the units.
c. Power Output
(1) Virginia Lake
Average annual inflow to the reservoir is estimated to be
414 cfs, or 300,000 acre-feet. Virginia Lake will have an active
storage of 91,700 acre-feet available for regulation between the
normal maximum reservoir elevation and minimum pool El 113. Oper-
ation studies determined that the average annual energy generated
from the Project is 44,000,000 kWh, which will result in 43,750,000
kWh being delivered to the load centers. The dependable capacity
is 9,000 kW, and 8,900 kW will be delivered to the load centers.
With a nominal installed capacity of 12,000 kW, the an-
nual plant factor under average conditions is 42%.
(2) Anita-Kunk Lakes
The nominal installed capacity of both power plants would
be 8,600 kW. An estimated 28,670,000 kWh of average energy would
be produced at the plant and would amount to 28,100,000 kWh deliv-
ered to the load centers. The dependable capacity as delivered to
the load centers would be 7,930 kW. The annual plant factor for
average conditions and based on the installed capacity would be 38%.
VI-3
(3) Thoms Lake
The Project would have a nominal installed capacity of
7,500 kW. It would be capable of generating 24,730,000 kWh on an
average annual basis which would amount to 24,240,000 kWh d~livered
at the load centers. It would have a dependable capacity of 7,390
kW delivered to the load centers. The annual plant factor for
average conditions and based on the installed capacity would be 38%.
(4) Sunrise Lake
The Project would have a nominal installed capacity of
4,000 kW. It would be capable of generating 13,780,000 kWh on an
average annual basis which would amount to 13,500,000 kWh delivered
at the load centers. It would have a dependable capacity of 3,920
kW delivered to the load centers. For average conditions and based
on the installed capacity it would have a 39% annual plant factor.
2. COMPARATIVE CONSTRUCTION COSTS
a. Basis for Costs
The preliminary estimates of construction costs used
for comparison of the hydroelectric alternatives were generally
developed using the basis described in Section VII for the more
detailed estimate of the Virginia Lake Project. The comparison
of the alternatives was based on broad reconnaissance level type
estimates. Costs were based on current prices and current con-
tractors' bid prices and were escalated to result in all projects
being on-line by September 1983. Escalation was based on a 7% an-
nual rate and 5% interest was used during construction based on
financing from the State Water Resources Revolving Loan Fund.
b. Construction Cost Estimate
The total investment cost for each project alternative
is shown in Table VI-3. As can be seen, the lowest cost project
VI-4
is Virginia Lake based on the total investment cost per kilowatt
of installed capacity.
3. COST OF POWER
a. Annual Costs
From the total investment cost shown in Table VI-3, the
estimated annual costs for each project were derived and are shown
in Table VI-4. These annual costs are based on debt service at
5%, 50-year financing, with associated financing costs and opera-
tion and maintenance charges.
b. Cost of Power
Based on the average annual energy estimated to be de-
livered to the load centers, the cost of power in mills/kWh was
derived and is shown in Table VI-4. This shows that the cost of
power for Virginia Lake is substantially less than the other al-
ternatives.
4. SELECTED PROJECT
The Virginia Lake Project is the most economic of the
rour hydroelectric alternatives considered. It would be capable
of meeting the forecasted load requirements for a period of about
4 years if it came on-line in late 1983. On the other hand, with-
out diesel generation, the Anita-Kunk Lakes Project would meet only
90% of the forecasted energy load in late 1983; the Thoms Lake Proj-
ect would meet only 85% of the forecasted load; and the Sunrise Lake
Project would meet only 57% of the forecasted load in the same
time frame.
The Virginia Lake Project was, therefore, selected as the
best candidate of the four sites for initial development. More de-
tailed project layouts, cost estimates and economic comparison,
were therefore made of this Project and are discussed in subsequent
sections of the report.
VIRGINIA LAKE PROJECT
ALTERNATIVE HYDROELECTRIC PROJECTS
SUMMARY OF PRELIMINARY PRINCIPAL PROJECT STATISTICS
PROJECT FEATURES
Drainage Area Above Dam, Sq. Mi ...
Mean Basin Elevation, Ft.
Average Annual Runoff at
Dam Site, efs .................. .
Headwater Elevation, Ft.:
Normal Maximum ................. .
Average
1 in 20 Year Minimum ........... .
Tailwater Elevation, Average, Ft ..
Net Head, Average, Ft ............ .
Power Conduit Discharge,
at Installed Capacity Output, cfs
POWER OUTPUT
Installed Capacity, kW ........... .
Dependable Capacity (Delivered),
kW (1) ......................... .
Average Annual Energy (Delivered),
MWh (1) ........................ .
Virginia Lake
40.6
1,500
414
200
178
113
4
164
1,070
12,000
8,900
43,750
Anita-Kunk
Anita Kunk
2.5 8.0
2,200 1,472
27 74
1,420 350
1,410 331
1,380 275
350 4
1,007 310
45 187
8,600
7,930
28,100
(1) -Delivered to total system -Wrangell and Petersburg.
Thoms Sunrise
19.0 1.16
900 2,300
158 15
300 2,000
293 1,993
270 1,978
4 300
274 1,608
371 34
7,500 4,000
7,390 3,920
24,240 13,500 8
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RESERVOIR OPERATION STUDIES-VIRGINIA LAKE NO~M.MAX. WIS. EL 200
SUMMARr OF BASIC INPUT DATA
RULE CURVE REeUIRED
GENERATION
MONTH ELEV(YT) STOR(AC·f'T) (PCT OF ANNUAL) ......•.• . .......•..•........ ...•.......•........
OCTC31,) 113.02 6150. B.SO
NOV(30.) 113.02 6150. B.80
DEC(31.) 113.02 6150. B.90
J"NC31') 113.02 &150. B.50
rEB(2B.) 113.02 6150. 7.90
MUQ31.) 113.02 6150. B.90
APR(30.) 113.02 6150. 7.30
MH(31') 113.02 6150. 7.70
JUN(30.) 113.02 6150. 7.70
JULC31.) 113 1 02 6150. B.60
AlIG(3l.) 113.02 6150. 8.70
SEP(30.) 113.02 6150. 8.50
ANNUAL REQD ENERGY (KWMO). 48000.
STARTING MONTH AND YEAR or DATA 10-1951
CRITICAL PERIOD --MONTH 0 THROUGH 0 (INCLUSIVE)
rIRST LEAP YEAR rEBRUARY --MONTH 29
MONTH
fISH RELEASE
IN ACRE-FEET
OCT
o.
NOV
o.
DEC JAN
o. o.
TAIL wATER ELEVATION 4.00 FEET
UNIT INSTALLED CAPACITY 16400, KW
RATED HEAD O. FEF.T
HYDRAULIC CAPACITY AT MAXIMUM HEAD O. CfS
BEGINNING STORAGE IN RESERVOIR 104000. ACRE-FEET
MAXIMUM RESERVOIR CAPACITY 104000. ACRE-FEET
rLOW ADJUSTMENT FACTOR (MULTIPLIER)
RESERVOIR CAPACITY CURVE
SYSTEM HEAD (rEET)
RES ELEV (FEET)
CAPACITY (ACRE-rEET)
100.00
104.00
0,
.56l3
111.00
115.00
7500.
116.00
120.00
12300.
rEB
o.
126.00
130.00
21800.
MAR
o.
136.00
140.00
31300.
(Q*H)/K
CONVERSION
K-FACTUR . .....•.••........•.
APR
O.
146.00
150.00
42100.
14.50
14.50
14,50
14 .50
14.50
14.50
14.50
14.50
14.50
14.50
14.50
14.50
MAY
o.
156.00
160.00
52900.
JUN
O.
166.00
170.00
65050.
JUL AUG SEP
O.
176.00
180.00
77200.
0, O.
196.00
200.00
104000.
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RESERVOIR O~ERATION STUDIES-VIRGINIA LA~E NORM.MAX. WISt EL 200
VIGINIA LK. FIRM HYDRO GENERATION KWMO
YEAR OCT NOV DEC JAN FEB MAR APR MAY JUN J'lL AUG SEP AVERACiE ... __ ..... ... -... . ...... ..-._.-....... ... ----. -.. -.---.-_ .. ----._ . .... --. . ....... ------. . .. ----.-.. ---
1951-52 4,090 4,224 4,272 4,080 3,792 4,272 3,504 3,696 3,696 4,128 4,176 4,OBO 4,000 <:
1952-53 4,080 4,224 4,272 4,OBO 3,792 4,272 3,504 3'/;96 3,696 4,128 411 76 4,080 4,000 H ::u 1953-54 4,080 4,224 4,272 4,OBO 3,792 4,272 3,504 3,b96 3,696 41128 4,176 4,080 4,000 Q
1954-55 4,080 4,224 4,272 4,080 3,792 4,272 3,504 3,b96 3,696 4,128 4,176 4,080 4,000 H
1955-56 4,080 4,224 4,272 4,OBO 3,792 4,272 31190 3,696 3,696 4,128 411 76 4,080 3,974 Z
H
1956-51 4,080 4,224 4,272 4,OBO 3,792 4,272 3,504 3,696 3,b96 4,128 4,176 4,080 4,000 ~
1957-58 4,080 4,224 4,272 4,080 3,792 4,272 3,504 3,696 3,696 4,128 4,176 4,080 4,000 t"-I
1958-59 4,080 4,224 4,272 4,080 3,792 4,272 3,504 3,696 3,696 4,128 4,176 4,080 4,000 ~
1959-60 4,080 4,224 4,272 4,080 3,792 4,272 3,504 3,696 3,696 4,128 4,176 4,080 4,000 ;::.;:
trl 1960-61 4,080 -4,224 4,272 4,~BO 3,792 4,272 3,504 3,696 3,696 4,128 411 76 4,080 4,000 0
t-cJ
1961-62 4,080 4,224 4,272 4,OBO 3,792 4,272 3,504 3,696 3,696 4,128 4,176 4,080 4,000 >:rj trl
1962-63 4,080 4,224 4,272 4, OB 0 3,792 4,272 3,504 3,696 3,696 4,128 4,176 4,080 4,000 ::u H ~ 1963-64 4,080 4,224 4,272 4,OBO 3,792 4,272 3,504 3,696 3,696 4,128 4,176 4,080 4,000 ::u 1-'3 1964-65 4,080 4,224 4,272 4,OBO 3,792 4,272 3,504 3,696 3,696 41128 4,176 4,080 4,000 ~ H
1965-66 4,080 4,224 4,272 4,OBO 3,792 4,272 3,504 3,696 3,696 4,128 4,176 4,080 4,000 ~ 0
>-<: z
191)6-67 4,080 4,224 4,n2 4,OBO 3,792 4,272 3,504 3,696 3,696 4,128 4,176 4,080 4,000 t:J (!)
1967-68 4,080 4,224 4,272 4,080 3,792 4,272 3,504 3,696 3,696 4,128 4,176 4,080 4,000 ::u 1-'3
1968-69 4,080 4,224 4,:272 4,080 3,792 4,272 3,504 3,696 3,696 4,128 4,176 4,080 4,000 0 c::::
1969-70 4,080 4,224 4,272 4,080 3,792 4,272 3,504 3,696 3,696 4,128 4,176 4,080 4,000 Q t:J
H 1970-71 4,080 4,224 4,272 4,080 3,792 4,272 3,504 3,696 3,696 4,128 4,176 4,080 4,000 M trl Z (!)
1971-72 4,080 4,224 4,272 4,080 3,792 4,272 3,504 3,696 3,696 4,128 4,176 4,080 4,000 M ::u
1972-73 4,080 4,224 4,272 4,080 3,792 4,272 3,504 3,696 3,696 4,128 4,176 4,080 4,000 ~
1973-14 4,080 4,224 4,272 4,080 3,792 4,272 3,504 3,696 3,6'16 4,128 4,176 4,080 4,000 1-'3
H ••..•.•... ....... . ...... . ...... ....... . ...... ....... . ... -.. ---.... . ..•... .... _--_ .. -.-. .... _--_._ .... 0 AVERAGE· 4,080 4,224 4,272 4,080 3,792 4,272 3,490 3,696 3,696 41128 411 76 4,080 3,999 Z
;::.;:
23-YEAR AVERAGE • 3,999 ~
~
0
RESERVOIR OPERATION STUDIES-VIRGINIA LAKE NORM,MAX. W.S. EL 200
VIRGINIA LK. TOTAL HYDRO GENERATION KWMO
YEAR OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP AVERAGE --_._ .. ---... -----..... -.. -.... ---.... . ...... ....... --..••. ....... .. _ .... ....... ....... _._--.-.......
1951-52 4,690 4,224 4,272 4,OBO 3,792 4,272 3,504 3,696 3,696 4012B 4,176 7,469 4,333
1952-53 10,157 4,224 4,272 4,080 3,792 4,272 3,504 3,696 3,696 4012B 4d76 7,592 4,799
1953-54 10d4B 4,224 4,272 4, OB a 3,792 4,272 3,504 3,&96 3,696 4,128 4,176 4,767 4,580 <! 1954-55 7 d80 6,221 4,272 4,080 3,792 4,272 3,504 3,696 3,696 4,854 12,411 8,848 5,509 H
1955-56 6,015 4,224 4,272 4,080 3,792 4,272 3,190 3,696 3,696 4d28 4d76 4,634 4 d81 :.:u
Q
4,080 3,504 3,696 3,696 6,351 6,335 7,713 4,82B H 195&-57 5,1!86 4,224 4dR7 3,792 4,272 :z: 19~7-58 5,414 4,964 4,272 4,080 3,792 4,272 3,504 3,696 3,696 5,543 9,548 5,094 4,823 H
1958-59 13,310 4,224 4,272 4,080 3,792 4,272 3,504 3,696 3,696 8,432 8,54) 6,990 5,734 ;J:>
1959-60 10,074 4,224 5,371 4,080 3,792 4,272 3 .. 504 3,696 4,757 12,015 10,180 8,322 6, 191 L-i 1960-61 12,(9) 4,224 4,272 4,080 3,792 4,272 3,504 3,696 5,038 10,013 10,401 8,109 6,175 ;J:>
~ 0 1961-62 16,3B6 4,224 4,272 4,080 3,792 4,272 3,504 3,696 5,163 10,774 9,031 10.104 6,608 tr:I f-d
1962-63 7,515 5,010 6,876 40386 4,690 4,272 3,504 3,696 7,322 9,069 5,368 11,992 6,142 trJ
1963-64 8,421 4,224 4,272 4,080 3,792 4,272 3,504 3,&96 3,696 6,497 10,317 5,612 5,199 ::u
;J:> 1964-65 8,520 4,224 4,272 4,080 3,792 4,272 3,504 3,696 3,696 4,128 4,176 4,080 4,370 8 8 1965-66 7,725 4,224 4,272 4,080 3,792 4,272 3,504 3,696 3,696 4 1128 4,176 4,080 4,)04 0 H 8 0 ;J:> :z: 1966-67 5,995 4,224 4,272 4,OBO 3,792 4,272 3,504 3,&96 3,696 4,128 4,176 7,797 4,4&9 L-i
1967-68 7,272 4,591 4,272 4,080 3,792 4,272 3,504 3,696 3,696 4,128 5,090 12,868 51105 ::r: CJ)
1968-&9 50330 4,224 4,272 4,080 3,792 4,272 3,504 3,696 3,696 4,128 4,176 4,711 4,157 f-<! 8
1969-70 4,645 9,533 4,272 4,080 3,792 4,272 3,504 3,696 3,696 7,944 10,256 10,226 5,826 t::J c:::
t::J 1970-71 6,914 4,4n 4,272 4,080 3,792 4,272 3,504 3,696 3,696 4,12B 4,176 5,399 4,363 ::u H 0 trJ
1971-72 5,497 4,224 4,272 4,080 3,792 4,272 3,504 3,696 3,696 4,12B 11,555 B,467 5,099 Q CJ)
1972-73 4,690 4,224 4,272 4,oBO 3,792 4,272 3,504 3,696 3,696 4 tl28 4,176 4,483 4,084 :rJ
1973-74 50170 4,224 4,272 4,oBO 3,792 4,272 3,504 3,696 3,696 4,128 4,455 9,769 4,5&8 :z:
t::rJ . ----_ .... .... _--....... ....... ....... ....... . ...... . ...... ---.. _. ....... ....... . ...•.• ....... ....... ::u AVERAGE 7,819 4,611 4,438 4,093 3,831 4,272 3,490 3,696 4,022 5,876 6,750 7,353 5,023 ;J:>
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PESEPVOI~ OPE~ATION STUDIES-VIRGINIA LAKE NORM.MAX. 1'1.5. EL 200
EOM RES,ELEV. fEET
n;AR OCT NOV DEC JAf, FEB MAR APR MAY JUN JUL AUG SEP AVERAGE -•... _ .... -.-..... . ...... .. --... ----.-. ._-.... ---_.-----.---. -------.-.---. ....... ....... . ...... . ......
<:
1951-52 200.00 193.65 184.flB 170.36 156.39 133.64 120.04 125.60 145.44 172.51 190.66 200.00 166.08 H ::u 1952-53 200.00 198.23 1 8 8.22 175.03 162.50 143.75 Hl.81 150.81 172.72 188.61 196.28 200.00 175.&6 Q
1953-54 200.00 196.95 189.51 177.05 179.60 163.89 148.66 149019 170.43 188016 194.09 200.00 179.79 H
1954-55 200.00 200.00 197.91 189.61 181.79 167.63 158.67 159.70 180.53 200.00 200.00 200.00 186.32 Z
1955-56 200.00 196016 183.1i8 168.62 153.29 127.90 113.02 134017 148012 166.91 195.48 200.00 165.63 H
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1956-57 200.00 199.911 200.00 189.16 178.34 161.59 151.65 164.22 189.28 200.00 200.00 200.00 186.18 t""'
1957-58 200.00 200.00 191.38 18 6.86 176.82 162.51 158.79 172.72 192.9 5 200.00 200.00 200.00 18&.84 :x::o
~ 1958-59 200.00 198012 192.93 181.9 2 171.06 155.73 147.23 156.81 18 3.09 200.00 200.00 200.00 182.24 tr! 1959-60 200.00 198.04 200.00 192.46 185.23 174.25 173.15 183.44 200.00 200.00 200.00 200.00 192.21
1960-61 200.00 1 9 7.97 194.96 187.72 182.94 172013 170.66 180013 200.00 200.00 200.00 200.00 190.54 0
tr! "D
1961-62 200.00 196.55 185.58 189.68 183.50 174.77 173.32 181.05 200.00 200.00 200.00 200.00 190.37 0 tr!
1962-63 200.00 200.00 200.00 200.00 200.00 190.30 185.60 193.80 200.00 200.00 200.00 200.00 197.47 :$ ::u
:x::o 1963-64 200.00 192.55 1 8 7.08 177.61 169.43 152.20 141.69 143.20 179.67 200.00 200.00 200.00 178.&2 ::u 1-3 1964-65 200.00 196.79 189.45 178.45 166.39 147.08 138.87 138.97 161.63 183.43 190.04 1 88 .53 173.30 tr! H
1965-66 200.00 1 9 1.81 1 8 0016 164.66 147.87 129.36 114.64 114.46 135.26 157.80 177.08 196017 159.11 Cfl 0
tTl Z
1966-67 200.00 197.52 185.77 172.18 161.06 140.18 120.41 122.93 147.96 163.64 183.06 200.00 166.23 ::u Cfl <: 1967-68 200.00 200.00 190.57 178.41 175.0& 1&6.54 151.37 165.81 179.93 197.77 200.00 200.00 184.29 0 1-3
1969-69 200.00 1 9 7.8& 185.84 170.56 155.31 130.29 114.65 125.77 157.28 177.52 196019 200.00 167.61 H ~
1969-70 200.00 200.00 196.94 185.39 179.43 167.63 159010 163.00 192.73 200.00 200.00 200.00 187.02 ::u t:J
H 1970-71 200.00 200.00 1 9 1.06 179.81 167.01 147.27 132.24 133011 158.24 176.11 195.11 200.00 173.33 tr! tr!
t""' Cfl
1971-72 200.00 194.90 183.82 169.55 158.51 145.62 127016 136.49 164.26 199.09 200.00 200.00 173.28 tr!
1972-73 200.00 193.86 181.57 170.56 158.13 137.26 121.88 125011 145.54 165.57 185.72 200.00 165.43 <:
:x::o 1973-74 200.00 190014 1 8 5.19 171.61 164.14 146.07, 13701~ 141.74 158.44 183.10 200.00 200.00 173.13 1-3 •...•..... ....... ....... ..-.... . --_._. _._._.-...... -.... -.. . _.--.---_.---....... ....... . ..... -. ...... H
AVERAGE :z00.00 197.00 189.85 179.45 170.17 153.81 143.38 150.53 172.33 187.94 195.81 199.33 178.29 0
Z
,.--.,
23-YEAR AVEPAGE • 178,29 ':rj
tr!
tr!
1-3
RESERVOIR OPERATION STUDIES-VIRGINIA LAKE NDR~l.MAX. W.S, EL 200
DISCH THRU UNI'tS,CFS
YEAR OCT NOV DEC JAN FEB MAR APR MA~ JUN JUL AUG SEP AVERAGE •••....... _ .... --. ..... -....... ....... ....... .... -.-_ .. --.. ....... --.. --. ----_.-........ _ ..... -. ......
<:
1951-52 347.0 317.6 334.5 340.9 345.0 43903 413.6 451.0 407.5 386.2 341.0 566.0 390.8 H
!:d 1952-53 751.4 313.9 327.4 333 01 333.7 415.4 379.8 390.3 339.7 338.8 321.3 567.1 401.0 Q
1953-54 7&5.5 314.9 327.3 330.0 315.4 369.3 333.7 369.8 344.0 341.5 323.6 358.0 374.4 H
1954-55 531.2 460.2 317.7 311.8 302.6 362.9 319.2 345.3 322.6 377 .9 918.2 654.6 435.3 Z
1955-56 445.0 315.& 333.0 343.5 350.3 453.5 397.1 448.1 390.8 389.9 341.7 346.8 379.6 H :r:-
1956-57 435.4 312.5 324.6 310.4 305.9 373.2 332.9 348.2 310.2 483.1 468.7 570.6 381 .3 t-<
1957·58 400.5 367.3 32301 319.6 309.2 373.9 324.3 331 .3 299.7 417.6 706.4 376.8 37901 :r:-
~ 1958-59 984.6 314.0 323.4 322.5 31 8.8 388.6 344.5 362.1 322.9 651.9 632.0 517 01 456.9 t:rl
1959-60 745.2 314.1 399.4 301.8 297.5 352.5 299.4 307.5 36 7.4 888.9 75301 615.7 470.7
1960-61 939.0 314.1 321.8 315.8 303.2 357.0 303.5 312.7 392.6 740.7 769.5 599.9 472.5 0
t:J '"""d
1961-62 1,212.2 315.3 331 • 1 322.2 301.1 353.7 401.4 797.1 t:rl 298.8 309.5 668.1 747.5 504.8 H !:d 1962-63 556.0 370.7 508.7 324.5 14 7.0 324.1 276.2 288.6 550.4 670.9 397.1 887.2 458.4 (fl :r:-
1963-64 623.0 318 .5 333.4 331.7 324.4 395.0 355.4 387.1 340.4 507.0 763.3 415.2 424.5 0 8
1964"65 630.3 315.1 327.5 328,8 326.5 405.6 3&5.6 397.2 366.3 355.2 331.4 31903 372.4 ::r:: H :r:-0 1965·66 588,7 319.2 340.4 351.3 361.1 460,1 430,6 484.8 443.4 420.0 370.5 323.9 407.8 !:d Z Q
1966"67 447.9 314.5 330.1 338,1 33 8.1 422,5 402.3 455.4 407.7 394.3 357.6 602.9 400.9 t:rl (fl
1967·68 538.0 j39.7 323.8 321.8 318.3 371.4 321.7 340.1 317.4 323.8 378.7 952.0 404.4 8 8 c:: 1968·69 394.3 314.2 329,8 339.6 346.0 441'.3 428.9 461.2 389.7 366.3 331.1 351.9 374 .9 ::r:: t:J
1969-70 343.6 705.3 318.5 316.1 308.2 365.4 318.8 341.2 308.2 598.8 758.8 756.5 453.3 !:d H
1970-71 511.5 327.8 323.4 32601 324.6 404.5 37403 416.5 378.3 366.8 333 .4 404.5 374.3 c:: trl
c:: (fl
1971·72 406.7 316.6 334.2 342.6 343.6 418.4 383.8 419.3 366.1 336.9 856.8 626.4 429.3 Z
H 1972·73 347.0 317.5 337.2 343.8 342.9 431.1 404.6 448.5 408.1 394.9 352.8 344.2 372.7 8
1973-74 382.5 320.6 337.3 339.2 335.5 409.9 369.2 395.7 366.9 358.9 344.4 722.7 390.2 (fl .-........ ... -.. -... -... .. -._.-._.-._-........ -._ ... -._ ... -.. ....... ....... ....... ...... -. . ...... . ......
AVERAGE 579 ,4 345,2 339.5 329.0 326.0 395.4 355.6 383.1 371.4 474.2 513.9 549.0 413.5 -----0
f:rj
(fl
2]·YEAR AVERAGE • 413 ,5
Vl
VIRGINIA LAKE PROJECT
HYDROELECTRIC ALTERNATIVES
ESTIMATED CONSTRUCTION COST SUMMARY
Project Cost {$l I OOO)
Item
1. Preparatory Work ................... .
2. Dam and Reservoir .................. .
3. Pressure Conduit ................... .
4. Power Plant and Switchyard ......... .
5. Transmission ......... ~ ............. .
TOTAL DIRECT CONSTRUCTION COST ....
Cont ingenc ies ...................... .
Subtotal ......................... .
Engineering & Owner Administration
TOTAL CONSTRUCTION COST
(Bid Date January 1977) .......... .
Interest During Construction (5%/yr.)
TOTAL INVESTMENT COST
(Bid January 1977, On-Line
September 1979) ................. .
Escalation (7%/yr.) ................ .
TOTAL INVESTMENT COST
(Bid January 1981, On-Line
September 1983) ................. .
Cost/kW (Total Investment Cost -
September 1983 and Installed
Capacity) ........................ .
Virginia Lake Anita-Kunk Thoms
$ 1,365
14,186
3,107
4,040
8,165
$30,863
4,629
$35,492
4,437
$39,929
3,570
$43,499
13 2 51 9
$57,018
4,752
$ 1,266
8,365
4,391
3,310
9,267
$26,599
3,990
$30,589
3,824
$34,412
3,076
$37,488
11,651
$49,139
5,714
$ 2,390
12,3 4 4
5,737
2,825
8,761
$32,057
4,809
$3 6 ,866
4 1 608
$41,474
3,708
$45,182
14,042
$59,224
7,897
Sunrise
$ 942
1,962
700
1,235
7 ,4 3 4
$12,273
1 2 841
$14,114
1,764
$15,878
1,419
$17,297
5,376
$22,673
5,668
TABLE VI-4
VIRGINIA LAKE PROJECT
HYDROELECTRIC ALTERNATIVES
COST OF POWER
Virginia
Lake
Anita-Kunk Thoms
Lakes Lake
Estimated Annual Costs
($1,000)(1) .. II II ...... " ................ $3,958 $3,410 $4,110
Average Annual Energy (GWh) ... 43.75 28.10 24.24
Cost of Power (Mills/kWh) . 91. 9 123.4 169.6
(1) -Based on 5%, 50-year financing.
Sunrise
Lake
$1,574
13.50
116.6
SECTION VII
ESTIMATED CONSTRUCTION COSTS AND SCHEDULE
1. GENERAL
Construction cost estimates were based on the layouts
shown in this report. Quantities were established for major civil
features and unit costs applied to arrive at the costs. Mechanical
and electrical item costs were based on preliminary quotations
from equipment suppliers for similar projects, catalog values and
adjusted with experience cost data for installation.
Estimated construction costs were prepared based on bid
prices previously developed in detail for similar projects, ad-
justed to a base January 1977 bid price level. These costs, there-
fore are considered to have built-in escalation which would permit
completion of a project by September 1979. The estimates were
then escalated to reflect receipt of major contract bids for each
project in January 1981 for construction completion by September
1983 which is considered to be the earliest reasonable on-line
date for any of the projects.
2. BASIS OF COSTS
a. Direct Construction Cost
This cost includes the total of all costs directly
chargeable to the construction of a project and in essence repre-
sents a contractor's bid. The base Direct Construction Costs are
adjusted to a January 1977 level.
b. Indirect Construction Costs
Indirect Costs are defined as those which are added to
the Direct Construction Cost to result in the Total Construction
VII-2
Cost. Indirect Costs include an allowance for contingencies, en-
gineering and client administration, and escalation where neces-
sary.
(1) Contingencies
To allow for unforeseen difficulties Quring construction
and to reflect items not included in the estimates, an allowance
of 15% for contingencies was applied to the Direct Construction
Cost estimates for all projects.
(2) Engineering and Owner Administration
These costs were based on actual experience with costs
for similar work. The item includes all preliminary engineering
work; project feasibility and environnlental studies; field inves-
tigations; processing of required permits and licenses; final de-
sign and preparation of construction contract documents; inspec-
tion of construction; and owner administration and legal costs.
An allowance of 12.5% of the sum of the Direct Construction Cost
plus Contingencies is considered a reasonable estimate for this
item.
( 3) Escalation
All costs were derived for a base bid price level of
January 1977. The earliest reasonable date for bidding major items
of work for a project is January 1981. Bid prices corresponding
to a bid date of January 1981, with all units in commercial opera-
tion in September 1983, have been based on an assumed annual escala-
tion rate of 7%.
c. Total Construction Cost
The Total Construction Cost includes the Direct Construc-
tion Cost plus Contingencies and Engineering and Owner Administra-
tion.
VII-3
d. Interest During Construction
Interest During Construction was determined based upon
an assumed cash flow developed from the construction schedule mod-
eled after similar projects. The interest rate during the con-
struction period has been assumed at 5%, 4% and 3% per year, which
is the range of values established for Alaska financing under the
State Water Resources Revolving Loan Fund Act.
e. Total Investment Cost
The Total Investment Cost is the sum of the Total Con-
struction Cost plus Interest During Construction.
3. CONSTRUCTION COST ESTIMATES
A cost estimate summary for the selected Virginia Lake
Project is presented in Table VII-l for 5%, 4% and 3% interest rates.
The respective Total Investment Costs are $54,173,000, $J5,093,000
and $56,013,000. A detailed cost estimate for the Virginia Lake
Project follows in Table VII-2. Total Capital Requirements for
funding the Virginia Lake Project with a loan from the Water Re-
sources Revolving Loan Fund are discussed in Section VIII.
4. DESIGN AND CONSTRUCTION SCHEDULE
A definite schedule for Project completion has not been
established. The earliest reasonable date for completion of the
Project is considered to be September 1983. This is based on the
time required for the initial feasibility evaluation studies, prep-
aration and processing of an FPC License Application, final fea-
sibility investigations, design and preparation of contract bid
documents, and equipment purchase and construction. A period of
18 to 20 months is assumed for the processing of the FPC License
Application. As can be seen, to avoid losing a year in the proj-
ect schedule, it is essential that the foundation investigations
VII-4
get underway by the fall of 1977. This will permit project evalua-
tion investigations to proceed to support the preparation of a
License Application for submittal by November 1978. A design and
schedule, is shown in Fig. 9.
VIRGINIA LAKE PROJECT
COST ESTIMATE SUMMARY
(Costs in $1,000)
Item
1. Preparatory Work ................... .
2. Dam and Reservoir .................. .
3. Pressure Conduit ................... .
4. Power Plant and Switchyard ......... .
5. Transmission ....................... .
TOTAL DIRECT CONSTRUCTION COST ..
Contingencies .. ~ . , ................. .
Subtotal ......................... .
Engineering and Owner Administration
TOTAL CONSTRUCTION COST
(Bid Date January 1977) ........ .
Interest During Construction ....... .
TOTAL INVESTMENT COST
(Bid January 1977, On-Line
September 1979) ............... .
Escalation (7%/yr.) ................ .
TOTAL INVESTMENT COST
(Bid January 1981, On-Line
September 1983) .............. ..
3%
$ 1,800
12,878
2,933
4,520
8,188
$30,319
4 2 548
$34,867
4,358
$39,225
2 2 10 3
$41,328
12,845
$54,173
Financing Terms
4% 5%
$ 1,800
12,878
2,933
4,520
8,188
$ 30,319
4,548
$34,867
4,358
$39,225
2,805
$42,030
13,063
$55,093
$ 1,800
12,878
2,933
4,520
8,188
$30,319
4,548
$34,867
4 2 358
$39,225
3 2 5 0 7
$42,732
13,281
$56,013
RWB
50-41
1.
2
PR~E~ Virginia Lake Project
R. W. Seck and Associate,
CONSTRUCTION COST ESTIMATE
FEATURE Virginia Lake Site LocATIoNPetersburg-Wrang e1 :I.w.o. WW-1523-HG2'-MA
TYPE EST: ~PLANNI NG '.lillUIIIII 1110811111 HEL TAKE-OFF RPM PRICED F :..;KD=-__ CALC. CHKD._DE_B ___ APPROVED _J,,-:-VW,-:,,-:::--:-----=-DATE August 1977
Bi d P 1 19 rice Leve January 77
ITEM AND DESCRIPTION QUANTITY lMlT MAT'L LABOR UNIT COST TOTAL
PREPARATORY WORK Sl 800 000
1.1 Mobilization LS , 435,000
1.2 Transmission Line Road 3.5 MI 70,000 ?L.'1 onn
1.3 Permanent Access Road 0.8 MI 150.000 120 000
DAM AND RESERVOIR 1$12,878,000
2 1 Rp!';ervoir C1earinl:! 500 AC 3500 , 750 000
2.2 Diversion Cofferdam & Care
of W.<ltf'r LS 250,000
2.3 Foundation Excavation
231 Common 37 000 CY 6.00 222,000
2 '1 ? Trpnc.h 36 000 CY 13.00 468 000
2 3 3 Cutoff (Rock) 5 550 CY 40.00 222,000
2,4 Foundation Treatment
241 Curtain Groutin~ 8 800 LF 30.00 264,000
2 5 Roc.kfi' ,
2.5.1 From Spillway Excava-
tion 390,000 CY 2.00 /~U,OOU
2 '1 ? Frnm Rnrrm.r '40 000 CY 9.00 1,2110,000
2 6 Conc.rete Facinl:!
2 f, , Rpddinl"! Materia' 33 000 CY 12.00 396,000
2.6.2 Concrete Face 7,100 CY 250.00 1, /l5,UOO
2.6.3 Concrete Toe 5 550 CY 250.00 1,388,000
2 6 4 Rpinfnrr.ement 426 000 LBS 0.65 277 ,000
2 n I) Cement 58 310 CNT 8.50 496,000
2 7 Sn i , h.r.<lV
271 CI Excavation 40 000 CY 6.00 240,000
2 7 2 Roc.k Excavation 300 000 CY 10.00 3,000 000
2 7 '1 Concrete 300 CY 200 00 fn 0"0
2 7 4 Reinfnrrpmpnt 24 000 LBS 0.65 16.000
2 7 '1 C:pmpnt 1 700 CWT 8.50 14 000
SheetLot~
r-3 ;x:.
tJj
t"-I
tr1
<:
H
H
I
f\.)
RWB
50-41
1
4.
5
PROJECT Virginia Lake Proj ect
R. W. Beck and Associate,
CONSTRUCTION COST ESTIMATE
FEATURE Virginia Lake MWS 20QOCATION Petersburg-Wrange1J..o. WW-1523-HG2-MA
TYPE EST: v'PLANNING PRlillie" ... 1UiIIIN:JiELTAKE OFF RPM PRICED F.K .. D.. CALC CHKD DEB APPROVED JVW DATEJune 27 1977 .--,
t . t'l P-ri ('Po Lev ~1 Januarv 19
ITEM AND DESCRIPTION QUANTITY \JIjIT MAT'L LABOR UNIT COST TOTAL
POWER CONDUIT 2 _933000
3 1 Intake Structure T.S 627 000
3 2 Conr-r:ete 6RO CY 600.00 l..OA 000
3 3 Cpmpnt 3 800 CWT 8 50 1') nnn
3 4 Reinforc.ement Rl 600 LRS o 6') "1 onn
3 5 Sl1rp-p T:lnk T.~ ~nn nnn
3 6 Stf'f'l Pens1'"ork 9' ~
(Inc1udim, SUDDorts) 693 200 LBS 1 75 1.213~000
POWERPLANT & SWITCHYARD 4 5?O 000
4 1 Structure Turbines ect 12 000 kW 100 00 l.. i.? 0 000
4 2 Switchvard LS 200 000
TRANSMISSION & SUBSTATIONS 8.188.000
5 1 Proif'c.t to Wran2:e11
5 1 1 Sl1hrn:lrinp T.S 1 67? 000
') 1 ? OvprhPo:lrl A MT Q() noo 00 no 000
') 2 Wr:lnp-p11 1'"0 Pp1'"f'rshllrQ
') ? 1 S, .hrn:lrinp T.S 3 226 .000
5 2 2 Overhead 2') MT qO 000 00 2 250 000
') 1 Sl1hst":l!'";nns
5 3. 1 Wr:lnCtpll 160 000
') 1 1 Pp!,"prshllrCt T.S 160 000
Total· S1011Q 000
Sheet ..£of....£
7
f-3
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b:I
l'
M
< H
H
I
IV
SECTION VIII
ECONOMIC ANALYSIS OF VIRGINIA LAKE PROJECT
1. GENERAL
Economic feasibility of the Virginia Lake Project was
determined based on a comparison of the cost of power of the Proj-
ect with that of the most economic alternative generating resource.
For the Petersburg and Wrangell electric utility systems, the most
economic alternative source of power generation is a diesel-elec-
tric unit located at the load centers. Gas turbines and coal-or
oil-fired steam generating units are not considered economic for
the magnitude of loads which the systems have now or will have in
the foreseeable future.
The Virginia Lake Project, as discussed in this report,
does not necessarily represent the optimum installation which
might be constructed at the site. Sizing of various project fea-
tures has been done on a preliminary basis considering two differ-
ent reservoir sizes in an effort to determine a project size which
will provide the greatest economic benefits, while keeping capital
investment costs to a minimum. Future, more detailed investigations
and economic evaluations may show that a slightly-different size,
arrangement, installed capacity or method of op~ration is desirable
and more economic; however, variations of a magnitude sufficient
to affect decisions based on the outcome of this study are not an-
ticipated.
2. ANNUAL COST OF VIRGINIA LAKE PROJECT
a. Capital Requirements
As discussed in Section VII, cost estimates for the Vir-
ginia Lake Project were prepared based on contract bids for the
VIII-2
major items of work being received around January 1981, which cor-
responds to an on-line date of September 1983. Project financing
has been assumed based on a loan from the Alaska Water Resources
Revolving Loan Fund (Fund) with a repayment period of 50 years,
and with interest only being paid during the construction period.
Under the provisions of the Fund, an interest rate of from 3% to
5% will be applied to loans for financing of hydroelectric projects,
if they are the most economical means of providing the power. Total
Capital Requirements are assumed to consist of the Total Invest-
ment Cost plus a Reserve Fund equal to one year of interest on
the debt which was assumed reinvested at the same rate of interest.
As shown in Table VIII-I, the Total Capital Requirements for the
Virginia Lake Project are estimated to be $55,848,000, $57,389,000
and $58,961,000 for loan interest rates of 3%, 4% and 5% respectively.
b. Fixed Charges on Investment
Financing arrangements for the Project from the Alaska
Water Resources Revolving Loan Fund are based on a term of 50 years
minus the construction period (47 years). Credit is taken for in-
vestment of the Reserve Fund at the same interest rate as the loan.
c. Total Operation and Maintenance Costs
Total operation and maintenance (O&M) costs for the Proj-
ect are based on FPC historic cost data and/or on actual estimates
of manpower and materials developed for similar sized projects.
The components of these costs and the basis for their determina-
tion are discussed in Table VIII-I.
d. Total Annual Costs
Total annual costs of the Virginia Lake Project are equal
to the Fixed Charges on Investment (Debt Service) plus O&M costs.
VIII-3
The annual cost for the first year of operation is shown in Table
VIII-I.
3. ANNUAL COST OF ALTERNATIVE DIESEL INSTALLATION
Construction costs were developed for an alternative die-
sel generating installation based on detailed cost estimates re-
cently developed for similar large, high plant factor diesel gen-
erating systems. Prices were estimated based on a July 1977 bid
level and assuming a 1-3/4-year construction period for what would
be a major diesel installation. An allowance of 5% for contingen-
cies was applied to the Direct Construction Cost Estimate. Engi-
neering and Owner Administration Costs were included at 7% of the
Direct Construction Cost plus Contingencies. It is assumed that
this investment would be financed from the sale of bonds. Finan-
cing costs are not significant and have not been included.
Annual costs of the diesel alternative include fixed
costs consisting of debt service and operation and maintenance
(O&M) and variable fuel costs. Debt service is for a 7%, 25-year
bond repayment period, and operation and maintenance costs are
based on historic maintenance cost experience of several southeast
Alaska communities which compare favorably with FPC data and other
sources. Variable annual costs (cost of diesel fuel) are based on
a January 1977 fuel price of 41¢ per gallon escalated at 7% per
year to the appropriate on-line date. Higher annual increases in
fuel costs have been experienced in recent years and future annual
increases could very well occur at a rate higher than the 7%; how-
ever, to be on the conservative side, 7% was used in this study.
Development of the Capital Cost, Total Capital Require-
ments, Fixed Annual Cost and Variable Annual Cost for a diesel in-
stallation are shown in Table VIII-2.
VIII-4
4. BENEFIT-COST RATIO AND COST OF POWER FOR FIRST YEAR
The first year annual cost of the Project was compared
with the annual cost of an alternative diesel generation plant
with a capacity equivalent to the dependable capacity of the Proj-
ect and producing the average annual energy delivered by the Proj-
ect to the load centers. The Benefit-Cost (B-C) ratios for the
Project based on 3%, 4% and 5% financing are 1.02, 0.88 and 0.77
and are shown in Table VIII-I. The first year power costs (1984)
based on 3%, 4% and 5% financing are 67.6, 78.3 and 89.9 mills/
kWh, respectively. The Benefit-Cost analyses were based on the
assumption that the excess energy produced by the Project through
mid-1986 would be purchased by industrial users that currently use
oil-fired generation at a cost less than the cost of fuel at that
time. These results show that the Project is economic the first
year of operation with 3% financing.
However, the first year B-C ratios and power costs for
a project do not provide a conclusive answer as to the economics
of a project over the long term. That determination should be a
function of how the Project and the alternative generation source
can meet forecasted loads over a reasonable time period and the
cost of power over that period. Hence, the Project is compared
over a longer term of operation as discussed below.
5. COST OF POWER FOR FIRST 10 YEARS OF OPERATION
In order to compare the estimated cost of power from the
Project over a reasonable long term, a ten-year period was selec-
ted for analysis. The resulting cost of meeting forecasted loads
with the Virginia Lake Project was compared with meeting the loads
with the alternative of diesel generation.
The estimated cost of power to meet the load over that
met by the Blind Slough Project for the years 1984 to 1994 for the
VIII-5
Project with 3%, 4% and 5% financing and the diesel alternative
is shown in Table VIII-3 and graphically in Fig. 10. Based on a
present worth analysis at 6%, the total savings for the Project
over the period with 3% and 4% financing when compared to the die-
sel alternative cost for the period are $3,850,000 and $392,000.
With 5% financing the cost of power from the Project over the pe-
riod exceeds the cost of power from the diesel alternative by
$3,384,000.
6. COMPARISON WITH THOMAS BAY PROJECT
The Phase 1, Thomas Bay Project, as studied in an earlier
report, (1) would have an installed capacity of 20,200 kW, and would
deliver 68,700,000 kWh. For comparative purposes, the cost of power
developed for Thomas Bay Phase 1, based on 5% interest financing,
was escalated to the same time frame as Virginia Lake. The cost,
assuming capitalization of the excess power in the early years, was
found to be 90.6 mills/kWh, which compares closely with 89.9 mills/
kWh from Virginia Lake. The Total Investment Cost for the Phase 1
Thomas Bay is estimated to be $81,141,000 for a September 1983 on-
line date.
VIRGINIA LAKE PROJECT
VIRGINIA LAKE AND DIESEL ALTERNATIVE
ANNUAL COSTS
TABLE VIII-l
Cost -$1,000
Item
PROJECT CAPITAL COST
Total Investment Cost (TIC) ...... .
Reserve Fund ..................... .
TOTAL CAPITAL REQUIREMENTS
( TC R) ( 1 ) ...................... .
PROJECT ANNUAL COST (2)
Debt Service (3) ................. .
Total Operation and Maintenance (4)
TOTAL ANNUAL PROJECT COST ...... .
Cost Per Kilowatt (5) ............ .
Cost of Energy in Mills/kWh (6)
ANNUAL COST OF DIESEL ALTERNATIVE (7)
Debt Service ..................... .
Operation and Maintenance ........ .
Variable Cost (Fuel Cost) ........ .
TOTAL ANNUAL COST .............. .
Cost of Energy in Mills/kWh ...... .
BENEFIT-COST RATIO (8) ............. .
3% 4% . 5%
54,173
1,675
55,848
2,227
731
2,958
4,514
67.6
1. 02
55,093
2,296
57,389
2,680
744
3,424
4,591
78.3
535
422
2~056
3,013
68.9
0.88
56,013
2,948
~8,961
3,177
756
3,933
4,667
89.9
0.77
(1) -Total Capital Requirements (TCR) equals Total Investment
Cost plus a reserve fund equal to one year of interest on
the debt.
(2) -Annual costs based on first year of operation (September
1983 through September 1984).
(3) -Includes credit for interest earned on reserve fund at 3%,
4% and 5%. Based on term of 50 years minus construction
period at 3%, 4% and 5% interest. Includes provision for
capitalization of differential cost of excess energy.
(4) -Based on 1.35% of TIC, and includes Operation and Mainte-
nance, Administration, Insurance and Interim Replacement
costs.
(5) -Based on Total Investment Cost and installed capacity.
(6) -Based on total annual costs and annual average energy
values given in Section VI delivered to the load center.
(7) -Fixed and variable annual costs of diesel generation de-
veloped in Table VIII-2, based on dependable capacity and
energy delivered to load center.
(8) -Ratio of total annual cost of alternative to total annual
Project cost at time of commercial operation.
TABLE VIII-2
VIRGINIA LAKE PROJECT
COST OF ALTERNATIVE DIESEL INSTALLATION(l)
CAPITAL COST -$/kW
Land, Site Development and Building ........ .
Engine Generators .......................... .
Electrical Equipment and Swltchyard ........ .
Dock and Fuel Unloading Facilities ......... .
Fuel Storage Facilities (2) ................ .
Initial Fuel Supply (2) .................... .
DIRECT CONSTRUCTION COST (3) ............... .
Contingencies (4) .......................... .
Subtotal ................................... .
Engineering and Owner Administration (5) ... .
TOTAL CONSTRUCTION COST (6) ................ .
Interest During Construction (7) ........... .
TOTAL CAPITAL REQUIREMENTS
(On-Line April 1979) ..................... .
TOTAL CAPITAL REQUIREMENTS -
September 1983 On-Line (8) ................ .
FIXED ANNUAL COST -$/kW (1983-84)
Debt Service (25 Years @ 7%) ............... .
Fixed O&M (9) .............................. .
VARIABLE ANNUAL COST -MILLS/kWh
Fuel Cost (10) ............................. .
Cost per kW
$ 35.00
290.00
49.00
10.00
35.00
35.27
$454.27
22.71
$476.98
33.39
$510.37
6.34
$516.71
$700.61
60.12
47.37
47.0 Mills/kWh
(1) -Costs based on dependable capacity delivered to the load
center for a large capacity (equal in size to the hydro
alternative) diesel base load plant.
(2) -Sufficient fuel for two months operation at 60% plant fac-
tor based on July 1977 fuel cost of 41 cents per gallon.
(3) -July 1977 Bid.
(4) -Contingencies at 5% of Direct Construction Cost.
(5) -7% of Direct Construction Cost plus Contingencies.
(6) -July 1977 bid, on-line 1-3/4 years later (4/79).
(7) -1-3/4 year construction period; 7% interest rate.
(8) -7% escalation from April 1979 to September 1983.
(9) -$30 per kW (1/77) escalated to September 1983 at 7%.
(10)-Based on 41 cents per gallon in 1977 escalated at 7% an-
nually to 1983-84 period; heat content of diesel fuel
140,000 Btu/gal. and average heat rate of diesel unit
10,000 Btu/kWh over life of plant.
VIRGINIA LAKE PROJECT
TEN-YEAR COST OF POWER ANALYSIS
(1984-1993)
($1,000)
Average Present la-Year
Cost of Worth Savings
Power Total (Deficit)
.!2!L ill.L 1986 1987 1988 1989 1990 1991 1992 1993 {Mi11slkWhl(~11000l ~~11000l
Virsinia Lake Project
5% Financing:
Debt Service ••••••••••••• 3,177 3,177 3,177 3,177 3,177 3,177 3,177 3,177 3,177 3,177
O&M •••••••••••••••••••••• 756 809 866 926 991 1,060 1,134 1,214 1,299 1,389
Total Annual ••••••••••• 3,933 3,984 4,043 4,103 4,168 4,237 4,311 4,391 4,476 4,566 96.5
Present Worth (1) II ••••• 3,710 3,546 3,395 3,250 3,115 2,987 2,867 2,755 2,649 2,550 30,824 (3,384)
4% Financing:
Debt Service ............. 2,680 2,680 2,680 2,680 2,680 2,680 2,680 2,680 2,680 2,680
O&M ••..••.••••••••••••••• 744 796 852 911 975 1,043 1,117 1,195 1,278 1,368
Total Annual ••••••••••• 3,424 3,476 3,532 3,591 3,655 3,723 3,797 3,875 3,958 4,048 84.8
Present Worth (1) ...... 3,230 3,094 2,966 2,844 2,731 2,625 2,525 2,431 2,342 2,260 27,048 392
3% Financing:
Debt Service ............. 2,227 2,227 2,227 2,227 2,227 2,227 2,227 2,227 ' %.227 2,227
O&M •....••••••••••••••••• 731 782 837 896 958 1,025 1,097 1,174 1,256 1,344
Total Annual ••••••••.•• 2,958 3,009 3,064 3,123 3,185 3,252 3,324 3,401 3,483 3,571 74.0
Present Worth (1) 2,791 2,678 2,573 2,474 2,380 2,293 2,211 2,134 2,062 1,994 23,590 3,850
Diesel Alternative
Debt Service ............... 535 535 535 535 535 535 535 535 535 535
O&M (Fixed) ................ 422 452 483 517 553 592 633 678 725 776
O&M (Fuel) ................. 1,598 1,861 2,154 2,522 2,697 2,884 3,087 3,303 3,535 3,781
Total Annual ••••••••••••• 2,555 2,848 3,174 3,574 3,785 4,011 4,255 4,516 4,795 5,092 88.2
Present Worth (1) ........ 2,410 2,535 2,665 2,830 2,828 2,828 2,830 2,833 2,838 2,843 27,440 ( -) ~
~
t""
t>:I
(1) -Present worth analysis based on 6% for both alternatives. <: (2) -Based on present worth values, H
H
H
I
I..U
SECTION IX
CONCLUSIONS AND RECOMMENDATIONS
1. CONCLUSIONS
a. Development of hydroelectric power at the Virginia Lake
site or at any of the three alternative sites, Anita-Kunk Lakes,
Thoms Lake and Sunrise Lake, is technically feasible.
b. The Virginia Lake Project is the only one of the four
studied that will meet the forecasted load requirements at the
on-line date of September 1983. The Project will have an installed
capacity of 12,000 kW with a 42% plant factor under an average net
head of 174 feet, and would deliver to the load center 43,750,000
kWh of average annual energy.
c. The estimated cost of power from the Anita-Kunk Lakes,
Thoms Lake and Sunrise Lake projects, is substantially greater
than the Virginia Lake Project.
d. The estimated Total Investment Cost for the Virginia
Lake Project coming on-line September 1983 is $54,173,000,
$55,093,000 and $56,013,000, for 3%, 4% and 5% financing respec-
tively.
e. With financing at 3%, 50-year term, the Project is eco-
nomically feasible the first year of operation. However, with fi-
nancing at 5% and 4%, 50-year term, the first year annual cost of
power from the Virginia Lake Project is more than that from alter-
native diesel generation.
f. The cost of power over the first 10 years of operation
is more economic from the Virginia Lake Project with 3% and 4% fi-
nancing than from alternative diesel generation.
IX-2
g. The cost of power from the Virginia Lake Project compares
closely with that estimated for the Phase 1 Thomas Bay Project.
The latter project would have a larger installed capacity (20,200 kW)
and Total Investment Cost ($81,141,000), for the same time frame.
The Thomas Bay Project would have somewhat more excess energy to
dispose of in the early years of operation, but on the other hand
would carry the load for some 10 to 12 years versus 6 to 7 years
for Virginia Lake, and is adaptable to economic second stage de-
velopment.
2. RECOMMENDATIONS
The following recommendations are submitted:
a. If satisfactory financing can be obtained, the Virginia
Lake Project should be considered for development by the Thomas
Bay Power Commission as the first hydroelectric facility to serve
the Petersburg-Wrangell area.
b. If the Commission considers that the additional capital
investment required for the Phase 1 Thomas Bay Project is justi-
fied in terms of the advantages of a larger project which is read-
ily capable of expansion, that project should also be considered
for initial development.
c. The Anita-Kunk Lakes Project, Thoms Lake Project and
Sunrise Lake Project are recommended to be dropped from further
consideration for development at this time.
d. The Commission proceed with the Evaluation level inves-
tigations and the preparation of an FPC License Application as soon
as possible with the view to having the selected project on-line
by late 1983.
IX-3
e. It is recommended that the Commission arrange to secure
financing for construction of the selected project for a 50-year
term, if possible at the lowest interest rate of 3% as provided
for in the Alaska Water Resources Revolving Loan Fund Act.
SECTION X
REFERENCES
1. Thomas Bay Project, Appraisal Report for the Thomas Bay Power
Commission by R. W. Beck and Associates, Inc., November 1975.
2. House Bill 171, Creation of a Water Resources Revolving Loan
Fund. Act Signed July 2, 1975.
3. House Bill 356, An Act Relating to the Water Resources Re-
volving Load Fund.
4. Alaska Power Survey, Federal Power Commission, 5 Volumes,
Dated 1969-1973.
5. Federal Power Commission, Hydroelectric Power Evaluation,
FPC P-35, March 1968.
6. University of Alaska, Institute of Social, Economic and Gov-
ernment Research, Kent Miller, Robert W. Retherford Associates,
Stefano-Me splay and Associates and National Economic Research
Associates, Electric Power in Alaska 1976-1995, March 19, 1976.
7. United States Department of the Interior and Alaska Power
Administration, Alaska Electric Power Statistics 1960-1975,
4th Ed., July 1976.
8. United States Department of the Interior, Geological Survey
Division, Geological Survey Water Supply Papers:
1372: Compilation of Records of Quantity and Quality of Sur-
face Waters of Alaska through September 1950; 1740: Compila-
tion of Records of Surface Waters of Alaska, October 1950 to
September 1960; 1936: Surface Water Supply of the United
States 1961-65, Part 15, Alaska; 2136: Surface Water Supply
of the United States 1966-70, Part 15, Alaska.
X-2
9. United States Geological Survey, Water Resources Division,
Alaska District, Open File Report -Flood Frequency in Alaska,
1970.
10. United States Department of Commerce, Technical Paper No. 47,
"Probable Maximum Precipitation and Rainfall -Frequency Data
for Alaska, for Areas to 400 Square Miles, Durations to 24
Hours, and Return Periods from 1 to 100 Years," 1963.
11. United States Department of Agriculture, Forest Service,
Joseph Cummings Dort, Water Powers of Southeastern Alaska,
1924.
12. United States Department of Agriculture, Forest Service and
Federal Power Commission, Water Powers Southeast Alaska, 1947.
13. Analysis of Electric System Requirements for City of Peters-
burg, Alaska by R. W. Beck and Associates, Inc., March 1974.
14. Paper, "Southeastern Power Needs," by J. V. Williamson,
R. W. Beck and Associates, Inc. Presented at Southeastern
Conference, October 1974.
15. Petersburg Municipal Power and Light -System Review and Plan-
ning Guidelines; by Robert W. Retherford Associates and Kent
Miller, November 1976.
Zarembo Island
Wrangell Island
Etolin Island
, ,
ALASKA \ CANADA , ,
\
PROJECT AREA
KEY MAP
LEGEND
o Powerhouse
~ Proposed Transmission Line
~ Reservoir
5
I
o
I
Scale
5 miles
I
R. W. BECK and ASSOCIATES
fNGINffRS AND CONSULTANTS
CoIumbu~ Nebr ....
Indi.n.polil,lndi.n.
s..ttI., W •• hington
Denver, Color.do
Phoeni .. , Arizon.
O~.ndo. Florid.
Wellesley, Maluchu .. tt.
DATE:
THOMAS BAY POWER COMMISSION
PETERSBURG-WRANGELL, ALASKA
VIRGINIA LAKE PROJECT
LOCATION MAP
AUG. 1977
FIG: I
~
~
I
>-
24
20
16
.... 12
() «
0.. «
()
8
4
o
--------
1976
f I I
Approximate schedule
for future hydro projec~
Existing Diesel
7,750 kW
Peak Load Plus Reserves ","""'-
1\ ","
","
/I'
",.-'" ."", . ~
~.l ---."", ~ ..
~ .".-----.. -"'~ .. ."",.",.. ~ -~ -
------..--
..,....,....".
------Existing Diesel
7,750 kW
1980
NOTES:
Blind Slough
21
1
00 k"t
1985
CALENDAR YEARS
I. Petersburg + Wrangell system load
2. 6% annual growth rate
3. Resource capacity is dependable,
delivered at load center.
.-
"""",
-","
",,-""
". ~"
Peak L':;!y
~' ,,'
."
"," / ~
/
~ ~
/
Virginia Lake Project
8,900 kW
1990
", "". ",/
V
y
1995
R. W. BECK and ASSOCIATES
CoIumbul, N.br.,k.
Indi"",,polil, Indi.".
ENGINEEItS AND CONSUlTANTS
S..III., W."'inCJh>n
Denv.r, CoIor.do Orl.ndo, Florid ..
Phoenix, Arilon. W.II.dey, ~.&Mch" .. th
THOMAS BAY POWER COMMISSION
PETERSBURG-WRANGELL,ALASKA
VIRGINIA LAKE PROJECT
VIRGINIA
PEAK
DATE:
AUG, 1977
LAKE
LOAD
ALTERNATIVE
GROWTH
FIG: 2
120
100
Approximate schedule / '/
for future hydro project ~
/ -
:I: 80 ;: I,/' ;:,c / 0 Y 0
Existing Diesel "\ o~ ~ 0 ~ ~ 0
o~ 60 ._-
-~ ~ " 1 ~ -->-Energy Load ~ ~ (!)
a:: ~r-.-~ w ",.,...,.. z w 40 .....--
~ ~ Virginia Lake Project
~ ---"""..---43,750,000 kWh -Existing D.iesel
20
Blind Slough
12,000,000 kWh
0 I I I
1976 1980 1985 1990 1995
CALENDAR YEARS
NOTES: R. W. BECK and ASSOCIATES
ENGINEERS AND CONSULTANTS
s..ttIo, W • .hi.flo.
I. Petersburg + Wrangell system load Columbu., N.b, .... Denver. CoIor.do O~ •• do, Florid.
IndianapoG,. Indiana Phoeni., ArizonA WeRe.iey. tr.4 •• wchu .. th
2. 6% annual growth rate THOMAS BAY POWER COMMISSION
3, Resource energy is average I delivered at load center PETERSBURG-WRANGELL,ALASKA
VIRGINIA LAKE PROJECT
VIRGINIA LAKE AL TERNATI V E
ENERGY LOAD GROWTH
DATE: l DRAWN: t A':1~OVED:
AU G. 1911 13,B/B I~ I FIG: 3
Dam Crest E I. 210
Rockfill Dam
Normal W. S. EI. 200
Access Road
~--__ Mill
o o
C\I
PLAN
9' L D. Steel Penstock
PROFI LE
\
o o
C\I
Tro"smi ssi 0)" e
,0
To Wrangell
and Petersburg
28'1.0. Surge Tank
I
Powerhouse
( 3-4000 kW units)
Normal water EI. 43
400'
I I I
o
I , I
400'
Scale
R. W. BECK and ASSOCIA rES
fNGINffRS AND CONSULTANTS
Cofumbu" N.br •• l.
Indianapolis. Indiana
Se.ttIe, W .. lUngton
Denver, CoIor.do
Phoenix, Ariton.
O~.ndo, Florid.
W ...... y, M .... e~u .. lb
DATE:
THOMAS BAY POWER COMMISSION
PETERSBURG-WRANGELL,ALASKA
VIRGINIA LAKE PROJECT
VIRGINIA
PLAN
LAKE PROJ ECT
AND PROFILE
AUG. 1977
FIG: 4
Power Intake
Structure
Normal
maximum W. S.
EI. 200""
Minimum W.S.
EI. 113 J\
I
I
Grout -'
Curtain ~I
2000
fAXiS of dam
Dam crest EI. 210
2:]1
1.5
~ROCk fill ...
9'0 diversion and
power conduit
EMBANKMENT SECTION
100' o ,,,,,'",., 100' ,
SURFACE
1500
Scale
AREA, ACRES
1000 500 o
250 ~-----*----r-----------r-----------r---~~--~ 250
....
IJ.I
W
U.
Normal maximum
EI. 200
~ 200 ~----------4-~~------~~----------+-----------~ 200
~
IJ.I
-I
W
a:
o
~ I 50 l------~__+_---------'~ ---------~------__; 150
W
CJ)
W a:
1ooL-----------~----------~----------~----------100
o 50 100 150 200
CAPACITY, 1000 AC-FT
AREA CAPACITY CURVE
400
.... 300 w w
U.
I
Z 200
0
~ « > 100 w
-I
W
0
0+00
rock line
2+00 4+00 6+00 8+00 10+00 12+00 14+00
HORIZONTAL STATIONS
PROFILE DAM
300 r---------.---------r---------.---------r---------r-------~
.... w w
U.
I
~200~~~~=Pc;=L~JJ~~rl6-~=4~~~~------~------~
~ >
W
-I
W
Inv. EI. 195.0
100
0+00 1+00
PENSTOCK
2+00 3+00
STATIONS
PROFILE SPILLWAY
Support Ring
TYPICAL SECTION AT SUPPORT
4+00 5+00 6+00
R. W. BECK and ASSOCIATES
CoIumbuI, Nebraaka
Indianapolil.lndiana
ENGINEERS AND CONSULTANTS
Orlando, Florid.
Seattle, W.,hington
Denver I Colorado
Phoenix, Ariton. Wellesley, MIII".chu .. ftt
THOMAS BAY POWER COMM'SSION
PETERSBURG-WRANGELL,ALASKA
DATE:
V IRGINIA LAKE PROJECT
VIRGINIA LAKE PROJECT
SECTIONS AND DETAILS
FIG:
AUG. 1977 5
1800
1600
o o
<D -
::Anlta Lake Reservoir::;!}}.. .. ·:.'
Normal W.S. EI. 1420:::,::::::';:::.:: '::.
JdffJI"",$>
Transmission Line
Construction
Access Road
Diversion Ditch
(
~ eO
Diversion Ditch ~ 0
) \~OO
D· . D 0 IverSlon am
\
'90 o
PLAN
Penstock
\
Powerhouse
(1-4300 kW unit)
\
1000' 0
11".t,,",
"'0 o
Scale
---.... ;:0.:..: J!
.·):;11'
•••••••••••••••••••••• , •••••••
1000'
I
R. W. BECK and ASSOCIATES
ENGINEERS AND CONSULTANTS
Suttt., W •• hingl ••
CoIumb •• , N.br .....
Indienepolil,lnd;.ne
O,nv." Coloredo Orlando. Flo,id.
Phoeni., A,itone WelHley, ~a'UI,hu .. th
THOMAS BAY POWER COMMISSION
P ETERSBURG-WRAN GELL I ALASKA
VIRGINIA LAKE PROJECT
ANITA -KUNK LAKES PROJECT
PLAN
DATE:
AUG. 1977
FIG: 6
o
, 2000
D '1 m,'ssion Line Trans
o Wrangell ~nd Petersburg
2000 __ ......
Ditch
0' 0
2010 11I!l11I1I11I1I1
II" Scale
,
2000
I
BECK and ASSOCIATES
R. W. D CONSULTANTS ENGINEEIIS AN
s .. ttI., W'''''_cpon
Den .. " Color •• Orlando, Rond. Colum,,"~ N.br..... """"iii., Arizona N
, ....... , .... _y POWER COMMISSI~KA
THOMAS SA WRANG ELL. ALA
PETERSBURG-KE PROJECT
Weles"y. Moluachu .. tt,
VIRGINIA LA
LAKE PROJECT THOMS PLAN
FIG: DATe, 1977 AUG. 7
I
I
f
~
o o
/()
C\J
'\
" \,
o o o
C\J
o o
!!!
",\
~ .............. -'-_'-Drainage Basin Boundary " r-'--,..-..~..,-~',
,~ .. "" ... :: ...
l'
~
~"
"""" ~
"y
i
f
i
\500
To Wrangell and )/{
--!etersburg ':-,.,../.,."
Transmission Line "I I .. ,..,..,.,. .... I -::.
1000' 0
I , , , , I , , , , I
Scale
1000'
I
R. W. BECK and ASSOCIATES
ENGINEERS AND CONSULTANTS
Columbus, Nebr •• ka
Indian.porie, Indiana
Seattle, Wa.hington
Denver, Colorado
Phoenix, Arilon
Orlando, Florid.
Wellesley, MOlSl1Ichu •• tt.
DATE:
THOMAS BAY POWER COMMISSION
PETERSBURG-WRANGELL. ALASKA
VIRGIN IA LAKE PROJECT
SUNRISE LAKE PROJECT
PLAN
FIG:
AUG. 1977 8
ITEM OF WORK
PHASE I-APPRAISAL REPORT
PHASE 11-EVALUATION REPORT
OFFICE STUDIES
FI ELD INVESTIGATIONS
PHASE III-FPC LICENSING
III A-APPLICATION
III B-FINAL FEASIBILITY
PHASE IV-FINAL DESIGN
IV A -ACCESS ROADS AND PORT
IVB-PROJECT
EQUIPMENT SPECIFICATIONS
BID PLANS
DETAI LED CONTRACT DRAWINGS
PHASE V-CONSTRUCTION
FIELD INSPECTION
CONSTRUCTION
ACCESS ROAD AND PORT
MAJOR EQUIPMENT
MAJOR CIVIL WORKS
STARTUP and TESTING
LEGEND
Major Effort
Continuing Effort 1 .. 1 .. 1111111111111
R. W. BECK and ASSOCIA TES
(N40INUIS AND CONSULTANTS
c.--...... NoI>r ....
s........ W.""otto.
0., • .,. CoIor.do
~.I.AriIOf'l'
0"".010. Ro.;,J.
h,eli .... poIi •. LftcItan. w ...... ';'. ~ •• wdltll_tt.
DATE,
THOMAS BAY POWER COMMISSION
PETERSBURG-WRANGELL,ALASKA
VIRGINIA LAKE PROJECT
DESIGN AND CONSTRUCTION
SCHEDULE
FIG,
AUG. 1977 9
I
0::
W
3t o
120
110
a.. 90
LL o
~ en o u
~ 80 «
0:: w
~
70
60
II
Diesel Alternativel~ I ,,'
........ 7' --On line September 11983 l"-
I I I
/'
" """" ..... r--
I
L,.o ~ i-""
~ ",...
i""'"
I-' ~""""
1983
~
-V· . I . L J P . I t /' / V Irglnla a e rOJec
~
......--....
...."..
~
1985
/~
(\c\(\~ ~
f·(\O
t ~ ~O ,,(eo __ ./
~~i-"""" V / --------/
~
~ ....
----
c\(\~ i f· (\0(\
/" ;' !>O~V---~
Dr 0/0'"
~ ...,.,..
~ ~ "",-
V ./ c~ ."
f\(\O(\
"(eot ~ .... ~O ~~.,-
~
1987 1989 1991 1993
CALENDAR YEAR
R. W. BECK and ASSOCIA rES
Columbu., N.b, •• k.
Indianapolis, Indiana
ENGINEERS AND CONSULTANTS
Orlando, Florid.
Seattle, Washin9ton
Denver, Colorado
Phoenix, Arizona Wellesley, Man.chutet ..
THOMAS BAY POWER COMMISSION
PETERSBU RG -WRAN GELL, ALASKA
VIRGIN IA LAKE PROJECT
COMPARISON OF SYSTEM POWER COSTS
DIESEL VS VIRGINIA LAKE
1984 -1994
10 AUG, 1977
DATE: FIG:
APPENDIX A
RECONNAISSANCE REPORT
BY
ALAN L. O'NEILL
CONSULTING GEOLOGIST
, .
...
ALAN L. O'NEILL
ENGINEERING GEOLOGIST
10B8 BUCHAN DRIVE
LAFAYETTE, CALifORNIA 84B48
41B·833.7821
R. W. Beck and Associates
200 Tower Building
Seattle, Washington 98101
Attention: Mr. D. E. Bowes
Gentlemen:
Subject: Thomas Bay Alternatives
INTRODUCTION
May 14, 1977
On May 2 and 3, 1977 the undersigned made a brief
reconnaissance of the Thomas Bay alternative project sites in
company with rlessrs. D. E. Bowes -and F. K. Dubar of R. W. Beck
and Associates. Messrs. S. J. Dixon of Converse, Davis, Dixon
Associates and C. Pool of Charles Pool Associates participated in
the inspection of the Virginia Lake Project site. The purpose
of the reconnaissance was to observe the physical setting at each
site and to obtain a visual concept of the geologic conditions
which should be considered in developing conparative costs of the
al~ernatives during appraisal engineering studies.
The reconnaissance was greatly facilitated by use of a
helicopter. Four alternative projects with five dan sites were
vi&wed giving only a short time to visit and evaluate each site.
There has been no exploration at any of the sites and there \'las
no background geologic site data aV8ilable; therefore, this report
will briefly summarize conclusions which I have drawn from the
very surficial inspection. Should planning; and design progress
beyond this appraisal stage, intensive ~eoloGic investigations
will be required and definitive data derived therefro~ should be
expected to refine mId/or alter the esti~ates and conclusions of
this report.
GENSRAL GEOLOGY
Information on the general geology was obtained from a
u. S. hureau of Reclamation report ti tIed "Thomas Bay Project,
Alaska, Geology" dated January 1962.
rv:etamorphic roclcs of the Wran[jell-Hevillagic;edo belt
and II gran ites" of the Coast Hanee batholith underlie the naiuland
and islands where the alteI'native sites are located. Interbedded
cherts, slates, phyllites, limestone (marble), greenstone and
R. W. Beck and Associates - 2 .-May 14, 1977
schist are the predominent rocks of the metamorphic series while
the "granites" range in composition from quartz diorite in the .
western part to granodiorite in the core of the batholith. The
"grain of the country" is northwesterly with a steep northeasterly
dip resulting from a strong general parallelism of the banding of
the quartz diorite, the gneissic foliation and schistosity of the
rocks. This strong .northwesterly trend is clearly vlslblo in
aerial photos near the Virginia Lake Project.
Glacial modification of the topography has occurred to
some extent at each of the alternative sites. At times during
the Pleistoceue Epoch, glaciers covered the entire region and at
other times valley glaciers fed by ice fields pushed into many of
the present day valleys. Retreat of the ~laciers left maI~
spectacular, scenic physiographic forms such as hanging valleys,
deep box like canyons, cliffs of polished barren rock and deep
fjords. The glacial retreat also was responsible for accumulations
of glacial drift in the form of moraines ruld outwash deposits.
VIRGINIA LAKE PROJECT
This project involves enlarginG Virginia Lake by building
a dam about 100 feet high on Trill Creek. A surface penstock would
convey the water to a powerhouse at tid e water. The water surface
elevation of the new lake would be about 200.
The outlet where Virginia Lake discharges into Nill Creek
is choked with a glacial deposit of sand, silt, and boulders. The
depth of this deposit is unknown; however, metamorphic bedrock is
exposed on both sides of the channel about 000 feet downstream
where the difference in elevation is about eight feet. The active
channel, which ranges from 50 to 150 feet in width, is filled with
alluvial deposits of unknown depth.
Bedrock at the site is a dark colored metasediment rang-
ing from schist to slate. The foliation reflects the regional
trend being about lOOe>vV and dipping about BO oNE.1'he rock has
several sets of joints, the most predominent having an attitude
of N60 0 E, 75°I~W.
Both abutments have a deposit of r,lacial debris covering
bedrock. The deposit appears to be of a lateral moraine type with
large blocks of Graui te up to 15 feet across on the surface. It
was not po~sible to identify the composition of the deposit because
of a heavy humus cover on th(} surface. Until better information
is available the dcposl t is assufficd to be l,lOstly ':I'anular wi th a
fair coutent of couble nnd boulder size rock.
R. W. Beck and Associates -3,-
Bedrock exists on each abutment above the glacial debris.
On the right abutment there 'is a steepening of the topography
abou t elevation 150. Al though bedrock could not be seen, it is
assumed that the beginnine of the steep slope marks the point
where bedrock lies directly beneath the humus cover. Metasediment
bedrock was seen along a trail about 200 feet downstream from the
proposed axis at about elevation 125.
The left abutment is marked by several muskeg covered
flats at about elevation 200. The glacial debris on this abutment
contains more visible large blocks than on the right ab,u tment. A .
brief traverse upstream in heavy vegetal cover confirmed that
bedrock exists at the surface at an elevation between 150 and 200.
This reconnaissance, althou~h brief, confirms that glacial
debris will be a factor in design of a dam at this site. It
appears that the amount of debris can be minimized by optimizing
the location of the axis slightly upstream of the working sketches
used for Qrientation.
Bedrock at the site is adequate for IDly type of dam.
Impervious material suitable for a clay core is in short supply;
therefore, either a concrete structure or a rockfill witll an
upstream i~pervious face are the most loeical choices. Early
concepts envision a rockfill dam with a concrete face. The
concrete toe slab for such a dam should be placed on a bedrock
foundation. On the right abutment the glacial deposits are esti-
mated to average 20 feet thick with the top at about elevation 150.
The deposits appear thicker on the left abutment and could average
about 40 feet thick with the top at about elevation 160. Shaping
and foundation preparation for the concrete toe below the glacial
material should average about 15 feet. Above the glacial debris,
preparation of the foundation for the concrete toe should include
the removal of about 5 feet of humus ar.d loose rock and an addi-
tional excavation of about 15 feet into rock. F'or estimating it
can be assumed that the depth of channel alluvium is 25 feet and
that five feet of sha;)inG of the rock would produce an acceptable
foundation. A deeper cut section is a possibility anywhere beueath
the glacial debris and will have to be carefully investigated.
Excavf}tion slopes in the glacial debris should be stable at 1.5:1
while cut slopes in the fresh bedrock can be planned at !:l. '
Consolidation and curtain grouting of the rOCIC foundation
should be planned beneath a concrete section. PIau consolidation
grouting on a 10 x 10 foot pattern with 20 foot deep holes.
Curtain holes can be estimated to be 80 feet deep on 10 foot centers.
Assume grout takes at 0.5 socks per foot of hole.
R. W. Beck and Associates -L~-May 14, 1977
Although we know very little about the composition of
the glacial debris, the nature of the deposit is such that a
predominently grrurular mass is likely. Therefore, at this stage
of planning, it is assumed that the bulk of the deposit can be
left in place beneath the rockfill section of the dam. Prepar-
ation of this foundation should include removal of about five
feet of humus and organically contaminated materials.
Rock for the fill can be obtained from a side channel
spillway cut. It appears that the right side offers the best
site for such a spillway excavation. The metamorphic rock can be
expected to produce many flat and elongated shapes; however, this
should not affect the quality of the fill. Excavation will have
to be carefully controlled to produce maximum fragmentation of the
spillway rock. In general the spillway rock should be competent
so that a concrete lined chute is not required for the entire
length. It may be necessar~,r to provide provision to prevent
erosion in localized areas, particularly if erosion could result
in an overflow above the toe of the dam. ~xcept for areas of local
instabili ty, cut slopes in the spillv/ay should be stable at !:l
in fresh rock and 1:1 for the top 20 feet in overburden and
weathered rock.
A cut ruld cover conduit may serve as the diversion
conduit and could be later utilized as the power conduit outlet.
The conduit can be founded on either side and should have a rock
foundation throughout. Shapin~ of the rock foundation will likely
average about five feet after removal of several feet of loose
overburden at the approximate elevation of the present stream.
If the conduit is placed on the right side, a scheme will have to
be developed to protect the penstock where it crosses the spillway
channel. Diversion could also be achieved with a tunnel in either
abutment. At this stage of planning assume that 2S7'b of the tunnel
length will require support. Shotcrete can serve as an adequate
lining for the period of diversion.
The penstock route can be located on either side of
Mill Creeko There are no special. problems envisioned at this time.
There is ample rock for a powerhouse foundation on either side
at the mouth of Mill Creek as it meets tidewater. It apnears
that a site can be selected where a good foundation can be
developed with a minimum of excavation.
Future exploration should be done at the junction of
~~ill Creek and Virginia Lnb_'l to see if a sufficient quantity of
concrete aegreGate is available. At this stage of plannin[; it
should be assumed that 8r~c;reg8te can be obtFlined at the upper end
of VirgInia Lake. Although we did not conduct a surface inspection,
R. W. Beck and Associates -5 -May 14, 1977
an aerial reconnaissance indicated that an aggregate source can
likely be developed in that area.
SUNRISE PROJECT
The reservoir for this project is located high atop
Woronkafski Island at about elevation 2000. Inclement weather
permitted only a short inspection and 'because of snow cover, it
was not possible to observe all features of the site. The penstock
alignment and powerhouse site were observed from t,he air.
This project has a very small drainage area ruld the
embankment would be on the order of 40 feet in height'. Foundation
for the dam would be granodiorite which has only a thin cover of
muskeg and some small brush and trees. A depression on the left
side could possibly serve as a natural spillway site. The rock
has a faint foliation that trends NIO-20W and dips near vertical.
The rock has a marked system of joints, many of which are open due
to frost jacking. A particularly strong set of joints strikes
N85°E and dips steeply N. The spacing of joints is from two inches
to two feet apart.
There are no impervious clay materials; therefore, the
dam wi 11 be ei ther a low concrete gravi ty or a concrete faced
rockfill. Beneath the concrete of either type drun stripping would
consist of removal of about 2 feet of muskeg, loose rock, and small
trees. Excavation into the granodiorite should require no more
than shaping and removaL of loose, jointed rock and should average
about five feet. Removal of the organic material should be all
that is necessary beneath the rockfill section. A rock source for
borrow could be developed in the near vicinity.
Because frost jacking of the rock is prevalent, estimates
should include consolidation grouting beheath concrete sections.
The left abutment ridge, which would separate the spillway from
the dam is narrow and appears to be loose, undoubtedly from the
effects of frost jacking. Grouting of the narrow rock mass should
be planned and it may be desirable to extend a concrete fac·e across
the front of this rock mass. A typical grout pattern for the
foundati on and left abu tmen t would be 10 x 10 fee t wi tIl 20 foot
holes. Assume grout take at 0.75 sacks per foot of hole.
The spillway will be in sound rock and aside from pro-
viding any necessary protection for the embankment, a control sill
and shaping would be all that is required.
A surface penstock of about 18 inches diameter would
service the powerhouse located at about elevDtion 300. rrhe
R. W. Beck and Associates .... 6 -May 14, 1977
penstock slope is precipitous and has rock exposed for the entire
distance. No problems are envisioned in obtaining an adequate
foundation or anchoraee for the penstock. Because of the slope
steepness, special safety precautions would have to be taken'
during construction to protect against falling rock. A eenerous
quantity of rock bolts should be included in the estimate to anchor
rock which could be loosened by construction or later frost action
and which could dama;:se the penstock.
Above the powerhouse site the slope appe~rs to flatten
so that rock falls would likely be contained and be a minimum
hazzard to the plant. This observation needs to be analyzed since
it will affect the type of powerhouse protection required, if any.
Rock excavation at the plant site would be expected to consist of
removal of 15 feet of loose rock and soil and 5 feet of additional
rock for shaping.
Factors which will affect costs of this project include
the difficult acc~ss, a short construction season because of the
elevation, frequent heavy cloud cover, and the steep terrane for
the penstock which could require extensive rock stabilization.
ANITA KUNK LAKES PROJECT
This project consists of two dams with associated pen-
stocks and powerhouses. Both dams would enlarge existing lakes.
Anita Lake is the upper reservoir and would have a maximum normal
water surface elevation of about 1420 while Kunk Lake, the lower
reservoir would have a maximum normal water surface elevation of
about 350.
Ani ta Lake trni t -'1'he darJ, which would be about 70 feet
high, would be located at the outlet of Anita Lake. Because of
ice and snow it was not possible to land 'at this si te j therefore,
observations of the si te condi tions were made from the air.
Foundation rock appears to be a granitic type with rock
exposed on the left abutment. The right abutment is covered with
talus which has f?~len from above. Talus on the lower part of the
slope could be on the order of 50 feet thick.
Because of construction material limitations, it is
assumed that the dam would be a concrete faced rockfill. The toe
slab of the concrete face should be founded on sound bedrock. On
the left abutment strippinG and excavation caE be estimated at
20 fe et in dep th. 'rhe right ab'.ltmellt es timates ShOllld include
removal of at least 50 feet of talus at the bottom tapering to
zero at ttlO top. An addi tional 20 feet of rOCK excav a tiou for
R. W. Beck and Associates - 7 -
May 14, 1977
preparation of the concrete toe foundation should. be estimated.
The channel section should be estimated to contain 25 feet of
alluvium and shaping of the underlying rock should average about
five feet. Excavation slopes in the talus should be stable at
1.5:1 while rock slopes can be estimated at ~:l. Consolidation
and curtain grouting should be provided beneath the toe slab. A
standard 10 x 10 foot p~ttern of 20 foot deep holes can be figured
for consolidation grouting while 60 foot deep curtain holes on
10 foot centers can be estimated. Grout takes should be estimated
at 0.5 sacks per foot of hole.
Talus deposits characteristically have a mixture of silty
to clayey soil with rock. If such is the case here, the talus
should be removed beneath the rock fill section of the dam. Until
it can be demonstrated that the talus is sui table for a foundation,
it is recommended that estimates provide for removal of all those
materials beneath the dam. Talus slopes should be stable at 1.5:1
while rock cuts can be estimated at ~:l.
A spillway would likely be excavated on the left side
and some of the rock for the enbankment could be obtained from that
excavation. RemaininlS required rock could be quarried nearby or
could be obtained by widening the spillway cut. The spillway rock
is expected to be of suitable quality so that a concrete lining
would not be necessary. It appears that concrete aegregate would
pave to be manufactured or be imported.
The penstock alignment follows Anita Creek and then the
1050 contour before dropping to a powerhouse at Kunk Lake. No
special problems are envisioned for construction of the penstock.
The powerhouse will be located at the base of, the slope on a
granite foundAtion. Because bedrock apparently drops off steeply
beneath Kunk Lake, the location of the powerhouse should be tight
against the hillside. Excavation of 10 feet of soil and loose rock,
and 15 feet of rock excavation should be estimated to provide a
sui table foundation. Protec tion of the structure from falling rock
should be provided. Cut slopes f6r the top 15 feet of all cuts
should be estimated at 1:1 while fresh rock cuts should be ·stable
at !:l.
Kunk Lake Uni t -'l'he drun would be located on Kunk Creek
a short distance downstream from ~he outlet of Kunk Lake. The dam,
estimated to be about 110 feet hip;h, would again likely be a con-
crete faced rock i"i 11 because of the scarci ty of ir:'cpervious clay
construction materials.
Left abu tr.lCllt rocl~ 1 s exposed in ou tcrops on a small
protrusion or nose in the topography. 'l'he rocks are corn.posed of
R. W. Beck and Associates - 8 -
fine-grained igneous types, generally of quartz diorite composi-
tion. Some of the rock could have been injected as dikes or sills
into the granitics. The attitutde of foliation is near that of the
re~ional trend, N30 0 W with a vertical dip. outcrops disappear
upstream of the nosej therefore, that topographic feature should
be utilized in location of the dam axis.
Bedrock is not exposed on the right side of the river
directly across from the left abutment nose although there are
granitic outcrops several hundred feet upstream.
The concrete portion of the structure should be founded
on rock and for planning purposes it can be assumed that 5 feet
of stripping and 15 feet of rock excavation will be required on
the left abutment. On the rie;ht abutment removal of rock and
overburden can be estimated at 10 feet of depth and rock excavation
will require an additional 15 feet. A curious flattening of the
slope about 30 feet above streaI'lbed makes the right side suspect
as to depth of rock; however, lacking more definitive information,
the estimates are considered reasonable. The channel section
should be estimated to contain 25 feet of debris and shaping of the
rock is all that would be required for a foundation. Consolida-
tion and curtain groutiuG of the foundation should be included as
estimated for Anita Dam. Overburden cuts can be estimated at
1.5:1 while rock cuts should be stable at ~:l.
A spillway is plrulned across the left abutment. It is
assumed that rock will be found at shallow depth and that the chute
can be unlined. Rock excavation should be sui table for the rock-
fill and additional rock can either be obtained by widening the
cut or from another nearby source. It appears that concrete
aggregate will either have to be manufactured or be imported. The
top 15 feet of cut should be estimated at 1:1 while fresh rock cuts
• 1. • can be deslgned at 2:1.
Alternative plaus f'or the penstock are being considered.
One plan involves a surface pipe about 2,200 feet long on grade
above Kunk Creek and then a drop to a powerhouse at tidewater.
No special problems are envisioned in locating the penstock on
the slopes. ~xcavation for footines should include an averaee
five feet of hur1Us and loose rock and excavation of an addi tional
five feet 01 rock should give a suitable foundation. 'l'he alter-
native scheme involves a tunne::" :'ror.! Kunk Lake to the top of the
pens tock which then drops directly to tl:1e powerhouse. 'l'he tunnel
would be about 1700 feet long. It is exp8cted that the tunnel will
be driven throu{~h generAlly cor:lpetent rocl{s. It will start in
granitic'rocks but rock types At the outlet end could not be deter-
mined from the air. It is possible that the tunnel will pass
R. W. Beck and Associates - 9 -
r:,ay 14, 1977
through contact zones. Therefore the estimates should include
provisions for 25 percent of the distance to be support with
moderate weight steel. A shotcrete buildup around the steel
should provide adequate protection against water flows. A provi-
sion should be included to provide shotcrete and/or rockbolt
treatment for seams and strongly jointed areas for an additional
25% of the tunnel. It is estimated that the remaining 50~ of the
tunnel can be left unlined. Portal slopes should be designed with
1:1 cuts for the top 10 feet and t:l cuts in the fresh rock.
Rock is well exposed along the shoreline at tidewater
end there are no special problems anticipated in developing a
foundction for the powerhouse. Excavation should include removal
of 5 feet of loose material and organics and an additional 10 feet
into rock for the foundation.
THOMS LAKE PROJECT
Our inspection of this project included stops at the
sites of the East and South Dams. 'The North Dam and Diversion Dam
sites were inspected frOM the air. All sites are muskeg covered
and we could not locate in-place rock. Also there was'no evidence
seen which would he_lp us to estimate the depth to sui table
foundation.
Numerous moderately large rounded, densely tree covered
hills exist west and southwest of Thoms Lake. These hills are
suggestive of lcame-like elacial structures. liVe were not ahle to
investigate these features but the suggestion is that the entire
area has a covering of glacial debris over rock. Existing Thoms
Lake has a water surface elevation of about 200; therefore, it might
be assumed that bedrock or some other impervious base exists not
too much below that elevation.
Lacking better information~ estimates for this ~ppraisal
study mieht assume a suitable foundation beneath 15 feet of muskeg
at each site. The dams would likeiy be concrete faced rockfills
and the foundation for the concrete toe would have to be shaped
and be excavated to good rock. It is estimated that a foundation
could be developed with an average of 10 additional feet of rock
excavation. Consolidation groutin~, as at other project sites,
should be provided.
'1'he concept sketch indicates a possibility of a snort
tunnel from the South Dam lendinr, to II supface penstock and a
powerhouse at tidewater. Because the small hill throuc;h which the
tunnel wbuld pass is suspectedi.;o be conposed of glacial moraine
type material, it is recommellded that II surface line be planned to
..
R. W. Beck and Associates -10 -May 14, 1977
the top of the oenstock. At this stage it should be assumed that
footings for pipe supports would be founded on unconsolidated
sediments. Bedrock was not seen in the vicinity of the powerhouse
site and it is assumed that rock may be too deep for a foundation.
Therefore, it is recommended that estimates be based on a founda-
tion designed for a granular unconsolidated material.
A quarry for rock could be developed within a mile of
the North Dam. A source for concrete aggregate was not seen, but
if the area contains the suspected glacial materia,1, it is likely
that good concrete aggregate could be obtained close to the si tes.
Regardless of a local source, if this project were constructed,
the read south from Wrangell would be extended to the project
area and would provide access to any aggregate sources along
its route.
CONCLUSIONS
1. The site appraisals given herein are based on a very
short reconnaissance, much from the air, and are considered very
rudimentary. Exploration will be required to confirm any or all
of the estimates given herein.
2. The most time was spent at the Virginia Lnke Project and
therefore we might consider our knowledge a little More complete.
There were no geologic conditions observed which would cause the
project to be rejected as an alternative.
·3. The Sunrise Project also is feasible from a geologic
standpoint. There is a difficult access problem and weather may
cause more difficulty in construction than at some of the other
alternatives •
4. The Anita-Kunk Lake Project appears to be a viable
alternative from the geologic staudpoint. Anita dar,! site may also
have a longer winter period than at other sites which could affect
construction schedules. The darn slte wIll likely have a deep
talus deposit on the right abutment. Hock at Kunk dam site.
appeared to be localized. Good ex1)10ratlon will be required at
each site to define the extent of' the problems.
5. 'l'he Thoms Lake Project hA.s three d~s and it was not
possible to confirm a sui table foundation at any of the si tes.
It is not believed that the project should be eliminated nt this
time for eeolor,ic reasons; however, if the project is cOEsidered
a highly desirable al tornative, it is recommended that our aerial
,
R. W. Beck and Associates -11 -May 14, 1977
observations be confirmed by ground inspection and early
exploration be planned at the dam sites to detormine if suitable
foundation and abutment condi tions can be developed.
Very truly yours,
~-LO&d£
Alan L •. O'Neill
Engineering Geologist