HomeMy WebLinkAboutBefore the Federal Energy Regulatory Commission Black Bear Lake Hydroelectric Project on Prince of Wales Island Alaska, Exhibits A to V 1982c
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r----BEFORE THE FEDERAL ENERGY_-----,
REGULATORY COMMISSION
LIBRARY COpy
BLACK BEAR LAKE
HYDROELECTRIC PROJECT
ON PRINCE OF WALES ISLAND, ALASKA
APPLICATION FOR LICENSE
AND
EXHIBITS A TO V
PROPERTY OF:
Alaska Power Authority
334 W. 5th Ave.
Anchorage, Alaska 99501
ANCHORAGE, ALASKA
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BEFORE THE FEDERAL ENERGY REGULATORY COMMISSION
APPLICATION FOR LICENSE
FOR THE
BLACK BEAR LAKE HYDROELECTRIC PROJECT
The Alaska Power Authority, a public corporation of the State
of Alaska in the Department of Commerce and Economic
Development, but with separate and independent legal existence,
and having its office and principal place of business at
Anchorage, in the State of Alaska, hereby makes application to
the Federal Energy Regulatory Commission for a license to
authorize the construction, operation, and maintenance of
certain project works fully described herein.
The name, title, and post office address of the person to whom
correspondence in regard to this application shall be addressed
is as follows:
Copies to:
Eric P. Yould, Executive Director
Alaska Power Authority
334 West 5th Avenue
Anchorage, Alaska 99501
Harza Engineering Company
150 South Wacker Drive
Chicago, Illinois 60606
Attention: R.R. Leonardson
The Applicant is a public corporation organized under the
following laws:
Chapter 83 of Title 44 of the Alaska Statutes
The measure of control or ownership exercised by the Applicant
in any other organization or over Applicant by any other
organization is as follows:
None.
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5.
6.
The Applicant operates and/or proposes to operate in the
following States:
Alaska.
A concise general description of the Project and the principal
project works is as follows:
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The Black Bear Lake Hydroelectric Project will almost fully I'
regulate the outflow of Black Bear Lake for power and energy
production. The Project will develop a rated net head
of 1,370 feet, have an installed capacity of 6 MW and produce
23.7 GWh average annual energy. Principal project works are as •
follows: Iii
a.
b.
c.
Dams and Reservoirs. A concrete gravity dam will be
constructed at the outlet of Black Bear Lake. The dam
will have a maximum structural height of 53 feet and a
crest length of 368 feet. The dam will be equipped with
an ungated overflow spillway having a maximum discharge
capacity of 1,680 cfs. The darn will raise the water
surface of Black Bear Lake by 35 feet creating a reservoir
with a maximum normal water surface level at El. 1715 feet
and a surface area of 241 acres, an increase of 29 acres
over the lake's natural area. 7he reservoir can be drawn
down to El. 1685 feet on a seasonal basis providing a live
storage capacity of 6,850 acre-feet.
Water Conductors. A 3-port intake, with ports at
different levels for water temperature control, will be
located on the face of the dam. Water will run through
the dam in a 4.0 foot diameter conduit and into a 4.0 foot
diameter steel penstock. Approximately 309 feet
downstream of the toe of the dam, the penstock will bend
into a 4.0 foot diameter concrete-lined vertical shaft.
A 2.5 foot diameter steel penstock will carry water from
the base of the shaft to the powerstation at which point
the penstock will bifurcate into two 14 inch diameter
steel penstocks, each supplying one turbine. The total
water conductor length is 4,410 feet.
Powerhouse, Substations and Switchyards. The two turbine,
generating units will be located in a concrete-block
conventional powerhouse. Each of the turbines will be
single-jet impulse units rated at 4,419 horsepower and
1,370 feet net head. At the rated head, each turbine will
discharge approximately 32 cfs. Each turbine will be
protected by a gate valve. Each of the turbines will be
directly coupled to a generator rated at 3,750 kVa at
0.8 power factor and 606 C temperature rise. The units
will operate at a speed of 600 rpm. A step-up substation
containing two 4,312 kVa, 4.16 kV/34.5 kV transformers
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d.
will be located adjacent to the powerstation. A step-down
substation rated 34.5 kV/7.2 kV with a capacity of
3,750 kVa will serve Klawock. The step-down transformer
at Craig will be rated 7.2-12.5 kV/4.l6 kV with a
capacity of 2000 kVa. Hydaburg will be served by a
2000 kVa stepdown transformer rated at 34.5 kV/4.l6 kV.
Transmission Lines. Power from the Project will be
supplied to the towns of Klawock, Craig and Hydaburg over
7.2/12.5 kV and 34.5 kV wood pole transmission lines
having a total length of 53.2 miles. The interconnection
to Klawock, Craig and Hydaburg is included in the Project
because the interconnection is part of the project
development and would not be constructed without the
Project.
7. The location of the Project applied for is as follows:
8.
9.
a. In the State of Alaska, Prince of Wales Island;
b. In the First Judicial Divison;
c.
d.
On the following-named stream: un-named stream commonly
called Black Bear Creek, carrying no commerce;
In the region of the following-named cities and towns:
Klawock, Craig and Hydaburg;
Lands of the United States which will be affected are located
in: the Tongass National Forest;
The proposed initial and ultimate scheme of development for the
Project is as follows:
The proposed initial scheme of development for the Project is
described in Item 6 above. There are no plans at present for
expansion of the Project beyond the initial development.
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10. The proposed use or market for the power to be developed
follows:
Power from the Project will replace that generated by
diesel-electric units in towns of Klawock, Craig and Hydaburg
and provide for future load growth. The estimated capacity and
energy requirements for these towns are:
Peak Capacity Annual Energy
Year Demand, MW Requirements, GWh
1980 (actual) 1.9 6.7
1986 4.7 17.4
1991 5.9 21. 9
1996 6.9 26.9
2001 8.2 32.2
11. The location, a brief description, and capacity of all power
plants or other electric facilities owned or operated by the
Applicant, the market supplied thereby, and the relation
thereof to the Project applied for are briefly described as
follows: the Applicant does not own or operate any powerplants
or other electric facilities.
12. The following Exhibits are filed herewith and are hereby made a
part of this application:
Exhibit A: Copies of the laws under authority of which application
is made.
Exhibit B: Certified copy of a resolution by
Alaska Power Authority authorizing the
application.
the Board of the
filing of this
Exhibit C: References to laws of the State of Alaska pertaining to
the Applicant's right to construct the Project.
Exhibit D: Evidence that the Applicant
requirements of the laws of
affecting the Project.
has
the
complied with the
State of Alaska
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Exhibit E: Statement concerning the nature, extent and ownership of
water rights. I
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Exhibit F: Statement concerning ownership of lands to be utilizec
in the proposed development •
Exhibit G: Statement of the Applicant's financial ability and
proposed method of financing the construction.
Exhibit H: Statement of the proposed operation of the project
works.
.. Exhibit I: Estimate of the dependable capacity and average annual
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Exhibit J:
Bxhibit K:
Exhibit L:
F.xhibit M:
Exhibit N:
Exhibit 0:
Exhibit R:
energy output to be generated by the Project.
General map covering the entire project area.
Detailed maps covering the entire project area.
General design drawings of the principal structures.
General description of the mechanical and electrical
equipment, and the transmission line.
Estimate of the cost of constructing the Project.
Statement of the time required to complete construction
of the Project.
Plan for public utilization of the project area for
recreational purposes.
Exhibit S: Report on the effect of the Project upon the fish and
wildlife resources in the area.
Exhibit T: A statement why the Project should be developed by the
Applicant rather than the Federal Government.
Exhibit V: A statement concerning the protection of natural,
-historic and scenic values in the project area.
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Exhibit W: Environmental report.
The following Exhibits are not filed here with:
Exhibit P: Not required by CFR
Exhibit 0: Not required by CFR
Exhibit U: Not required
25,000 kW.
Project installed capacity less than
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IN WITNESS WHEREOF the Applicant has caused its name to be
hereunto signed by Eric P. You1d, the Executive Director
of the Alaska Power Authority and its Corporate Seal to be
hereto affixed by Eric P. You1d, its Secretary thereunto
duly authorized this 4~ day of J:)c::.<A-"",,\'''' ,] 981.
ALASKA POWER AUTHORITY
By: ". Executive or and Secretary
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VERIFICATION
STATE OF AlASKA
ss:
~i~d Judicial Division, ss:
Eric P.-Yould being first duly sworn deposes and says: That he
is the Executive Directo~ of the Alaska Power Authority, the
Applicant tor a license, that he has read the foregoing
application and knows the contents thereof; that the. same are
true to the best ot his knowledge and celief.
ExecutiVe' Director
Subsc~ibed and sworn to before this 24 day of November , 1981
Notary Public
My commission expires ~ -I t: ~ 7-
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BLACK BEAR LAKE HYDROELECTRIC PROJECT
FERC NO. 5715
EXHIBIT A
COPIES OF THE LAWS UNDER AUTHORITY
OF WHICH APPLICATION IS MADE
ALASKA POWER AUTHORITY
ANCHORAGE, ALASKA
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Black Bear lake -Exhibits A-V
Exhibit A
EXHIBIT A
rAWS UNDER AUI'HORITY OF
WHICH APPLICATION IS MADE
The Applicant is a public oorporation of the State of Alaska in the
Depart:nent of Comrerce and Eoonanic Developrent but with separate and
independent legal E>..xistance. The Applicant is E!Il'pOWered to oonstruct,
acquire, finance, and operate power production facilities. In addition
to its other powers the Applicant can issue bonds to carry out its
oorporate purposes, and enter into oontracts for the sale or
transmission of power for the security of any bonds issued for projects.
The items included under Exhibit A are as follavs:
1. A copy of Alaska Statutes, Title 44, Chapter 83, Sections 070 and
080 which specifically describe the purpose and powers of the
Alaska PcMer Authority.
Specific enabling authority for applications is oontained in AS
44.83.080(12) which enpowers the Authority to apply to agencies of the
United States for penni ts and licenses necessary to oonstruct, operate,
and maintain power projects.
Article 2. Purpose and Powers.
Sectiun
"10. Purpoac of lhe authority
80. Powen of lhe aUlhority
Seelion
90. Power c:ontratls and lhe Alaska Public
Utilities COlI\miuion
Sec. 44.83.070. PUl'pose of the uuthoriLy. The purpose of the
authority is to .promote, develop and advancc the cenerul prosperity
nnd economic welfare of the people of Alaska by providing a mellllS of
constructing, acquiring, financing and operating power production
facilities limiled to fossil fuel, wind pnwer, tidal, geothermal,
hydroelectric, or solar energy production and wasle energy
conservation facilities. (§ 1 eh 278 SLA 1976; am § 5 ch 156 SLA 1978)
J-:rrect of amendment. -The 1978
amendment 5ubstituted the language
beginning "power production facililies" fol'
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"hydroelectric Bnd fossil fuel I(I~nerllling
prnjeC'ls" Bt the end of the seclion.
Sec. 44.83.080. Powers of the authority. In furtherance of its
corporate purposes, the authority has the foUowing powers in addition
to its other powers:
(l) to sue and be sued;
(2) to have u seal and ult('r il at pleasure;
(3) to make and alter b~luws for its organization nnu in\erJlul
m:lOagement;
(4) t.o make rules and regulations governing the exercise of its
corpornte powers;
(5) to acquire, whether by construction, purchasc, gift or lease, and
to improve, equip, operate, nnd maintain power projects;
(6) to issue bonds to carry out any of its cnrpornte purposes and
powt:rs, including the acquisition or construction of a project' to be
owned or leased, as lessor or lessee, by the authority, or by another
person, or lhe acquisition of any interest in a project or any right to
capacity of a project, the establishment or increase of reserves to secure
or to pay the bonds or interest on them, and the payment of all other
costs or expenses of lhe authority incident to and necessary or
convenient to carry out its corpornte purposes and powers;
(7) to sell, lease as lessor or lessee, exchange, donate, conveyor'
encumber in any manner by mortgage or by crealion of any other
security interest, real or personal property owned by il, or in which it
has an interest, when, in the judgment of the authority, the action is
in furtherance of its corporate purposes;
(8) to accept gifts, grants or loans from, and enter into contracts or
other transact.ions regarding them, with any person;
(9) to deposit or invest its funds, subject to ngrcements with
bondholders;
(10) to enter into contracts with the United States or any p(!rson and,
subject to the laws of the United States and subject to concurrence of
the legislature, with a foreign counlry or ils agencies, for the flllancing,
construction, acquisition, operation and maintenance of all or nny part
ofa power project, either inside or outside the state, and for the sule or
transmission of power from a project or nny right to the capacity of it
or for the security of any bonds of the authority issued or to be issued
(or the project;
(11) to enter into contracts with any person nnd with the United
Stales, and, subject to the laws of the United Stntcs and suhject to the
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§ 44.83.080 ALASKA STATUTES § 44.83.080
concurrence of the legislature, wi th a foreign country or its agencies for
the purchase, sale, exchange. transmission, or use of power from a
project, or any right to the capacity of it;
(12) to apply to the appropriate agencies of the state, the United
States and to a foreign country and any other proper agency for the
permits, licenses, or approvals as may be necessary, and to construct.
maintain and operate power projects in accordance with the licenses or
permits, and to obtain, hold and use the licenses and permits in the same
manner as any other person or oper3ting unit;
(13) to perform reconnaissance studies, feasibility studies, and
engineering and design with respect to power projects;
(14) to enter inlo contracts or agreements with respect to the exer·
cise of any of its powers, and do all things necessary or convenient to
carry out its corpomte purposes and exercise the powers granted in this
chapter;
(15) to exercise the power of eminent domnin in accordance with AS
09.55.250 -09.55.410;
(16) to recommend to the legislature
(A) the issuance of general obligation bonds of the stale to finance
lhe construction of a power, project if the authority first determines that
the project cannot be linanccd by revenue bonds of the aulhority at
I'l'usonable rales of interest;
(3) the pledge of the credit of the state to guarantee repayment of all
or any portion of revenue bonds issued to 3ssist in construction of power
projects;
(C) an appropriation from the general fund
(i) for debt service on bonds or other project purposes; or
(ii) to reduce the amount of debt financing for the project;
(D) an appropriation to the ;,lowe I' project fund for a power project;
(E) an appropriation of a part cir the income of the renewable
resources investment fund for a power project;
(F) development of a project under financing arrangements with
other entities using leveraged leases or other financing methods. (§ 1
ch 278 SLA 1976; am §§ 6 -11 ch 156 SLA 1978; am §§ 16. 17 ch 83
SLA 1980)
Err~ct or Ilmcndments. -The 1978
amendmenL suhstituLed "cquip, operaLe.
and mainLain" ror "cquip and operatc" in
p:lrugraph (51. inllerled "or hy anoLher pel"'
lOOn" in paragr:lph 161, sub5titul!~11 ":1
projccL" ror "iL" in t ..... o plaCl!S in para~raph
161. substituted ":lny person" rol' na fcoeral
Ilger\('y or an ngency or instrumenlalily of
the slole. municipality. privaLe
orKDnitalion or other !Inure!!" in pnraJ,:r:lph
(81, inserted "linancing" ncar the middle of
paragraph (101. delell'd "ror the purchase.
,ale, exchange.".lransmi5:lion. or use or
power genl:raled lJy a projcCL. or any righl
to thc capaciLy or it" rollowing "enLer into
cnntr:lcLs" near the be.:inning of para·
J.:rapb (Ill. :1uI]eu the lanJ,:uage bc~inninK
"for Lhe purchuse. sale. exchanl(e" to Lhe
end of paragraph (11', and dl:leLecl
"hydroclecLrical and foslIil fuel" following
"wiLh respecL LO" and ""enerating" rolluw.
inK "power" in par:ll(raph (1:11.
The 19HO amendmenL inserLed in the
middle of paragraph (131, "rcasibilily
sludics. and e:nginecrinK and design." and
added paragraph 1\61.
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BLACK BEAR LAKE HYDROELECTRIC PROJECT
FERC NO. 5715
EXHIBIT B
CERTIFIED COpy OF A RESOLUTION BY
THE BOARD OF THE ALASKA POWER AUTHORITY
AUTHORIZING THE FILING OF THIS APPLICATION
ALASKA POWER AUTHORITY
ANCHORAGE, ALASKA
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CERTI FICJl.TE
I, ERIC P. YOULD, Executive Director/Secretary of the Alaska Power
Authority, HEREBY CERTIFY that the attached is a true and correct copy
of Resolution No. 1982-4 adopted at a meeting of the Authority held on
January 22, 1982 and that said resolution has not been amended,
repealed or rescinded.
IN WITNESS WHEREOF, I have hereunto set my hand and seal of the
Authority, this J!l!!!-day of April, 1982.
ERI P.ULD \
Executive Director/Secretary
(SEAL ).
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AIASKA 1?G.lER AUl'OORITY
RESOLUTICN NO. 1982-. .-4
RESOLUI'ION OF THE AIASKA PGlER AUl'HORITY OOARD OF
DIREX:'IDRS 'ro PROCEED wrm AN APPLICATIGT FOR LICENSE
WITH THE FEDERAL ENERGY REX;UIA'1ORY CCHfiSSICN FOR
THE J3IAa{ BEAR lAKE HYDROEI..Frl'RIC Pro:JECl'
WHEREAS, the entire electrical generation on Prince of \<lales
Island is now provided by diesel electric generating units1 and
WHEREAS, the ccmrunities of Prince of Wales Island, narrely
Craig, Klawock and Hydaburg are expected to need significant increm:mts
of additional generat.ing capacity by 19901 and
WHEREAS, the Alaska Power Authority has conducted a detailed
feasibility study of the Black Bear Lake Hydroelectric Project and other
alternatives to neet the area's electrical energy needs and fotmd the
Black Bear Lake Project to be the least cost alternative to neeting the
area's anticipated demand1 and
WHEFEAS, the findings and reccmnendations conclude that
licensing and design of the Black Bear Lake Hydroelectric Project should
proceed so it may be fully operational by January 19861 and
WHEREAS, it is now appropriate and t:irrely that an application
for license to construct the project be filed \oath the Federal Energy
Regulatory Carmission by the Alaska Power Authority.
NCM, THEREFORE, BE IT RFSOLVED by the Authority:
Section 1. That the Executive Director of the Authority be
and hereby is authorized to file a fonnal application for license to
construct the Project with the Federal Energy Regulatory Carmission.
Section 2. That the Executive Director of the Authority is
diJ:ected to file with the Federal Energy Regulatory Ccmn:ission as a part
of the fonnal license application, a certified copy of this resolution.
This resolution having been su1:mi.tted to a vote, the vote
thereon was as follows:
~:Mssrs. Mueller. Ward. Lehr. Conway and Mrs. Cook
Nroffi:~N~on~e~ ____________________________ __
ABSENT: Mssrs Weeden and Schaeffer
And the resolution was declared adopted on this 22nd day
of "a""ar.v , 1982.
AT T EST:
BY:~~;-~. ~~
Executive Directo
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BLACK BEAR LAKE HYDROELECTRIC PROJECT
FERC NO. 5715
EXHIBIT C
REFERENCES TO LAWS OF THE
STATE OF ALASKA PERTAINING TO THE
APPLICANT'S RIGHT TO CONSTRUCT THE PROJECT
ALASKA POWER AUTHORITY
ANCHORAGE, ALASKA
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Black Bear Lake
EXhibit C
C.1 APPLICANI" S STATUS
EXHIBIT C
IAr-1S OF THE ~TE OF AUoSKA
PERTAINING 'ID THE APPLICANl' I S
RIGHT 'ID CONSTRHCT THE P~
The Applicant's right to furnish electric service was granted by the
State of Alaska, under authority vested in it by Alaska Statutes, Title
44, Chapter 83. Reference is made to Exhibit A.
C.2 APPLlCANI'S RIGHT 'ID UI'ILIZE WATER IN THE PRQJ.OCT AREA
The appropriation and use of streams and rivers in the State are
governed by the provisions of Alaska Statutes, Title 46, Chapter 15 -
\..;rater Use Act.
The oppJning section reads:
"Section 46.15.010. Detennination of Water Fights. The Depa.rtnent
of Natural Resources shall determine and adjudicate rights to the
waters of the state, and in its appropriate and distribution."
Accordingly, the Applicant has submitted a request to the Depar1::Irent of
Natural Resources for permission to utilize Black Bear Lake waters for
power generation purposes. A copy of the application is included as
part of Exhibit D.
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OF
BLACK BEAR LAKE HYDROELECTRIC PROJECT
FERC NO. 5715
EXHIBIT D
EVIDENCE THAT THE APPLICANT HAS COMPLIED
WITH THE REQUIREMENTS OF THE LAWS
THE STATE OF ALASKA AFFECTING THE PROJECT
ALASKA POWER AUTHORITY
ANCHORAGE, ALASKA
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Black Bear Lake -Exhibits A-V
Exhibit D
EXHIBIT D
EVIDENCE THAT THE APPLICANT
HP..s ro1PLIED WITH THE RmUIREMENTS
OF THE STATE OF ALASKA
As evidence that the Applicant has corrplied with the requirenents of the
State of Alaska with respect to appropriation , diversion and use of
water for power purposes, the following dOCUITEnts are submitted:
1. Copy of application for water rights;
2. Copy of application to construct or rocx:lify a dam;
3. Copy of a letter frem the state Division of Forest, Land and
Water t-fanagerlY?'nt regarding deferral to FF.RC for dam safety
considerations.
333 WEST 4th AVENUE -SUITE 31 -ANCHORAGE, ALASKA 99501
CERTIFIED MAIL #2906178
RETURN RECEIPT REQUESTED
Mr. Robert Merry
District Water Officer
Division of Forest Land and
Water Management
230 South Franklin Street, Rm. 417
Juneau, Alaska 99801
Dear Mr. Merry:
August 7, 1981
Phone: (907) 277-7641
(907) 276-2715
Enclosed please find our application for water rights in the amount
of 64 cfs for the Black Bear Lake Hydroelectric Project on Prince of
Wales Island near Klawock. The project will involve the construction of
a 53 foot high (foundation to crest) dam at the outlet of Black Bear
Lake to raise the lake level and create a reservoir with 6850 acre feet
of active storage covering 247 acres. The water will be conveyed from
the dam through a 4.0 foot diameter, 294 foot long steel penstock to a
4.0 foot diameter concrete lined 1296 foot vertical shaft then through a
2.5 foot diameter, 2790 foot long steel penstock to a powerhouse with
two 3.0 MW single nozzle impulse turbines. Electricity from the project
will serve the communities of Craig, Klawock and Hydaburg via a transmission
1 ine intertie.
Your office and other agencies have received and reviewed copies of
the draft feasibility report. The report is nearly finalized and will
be provided to your office and reviewing agencies as supplemental information
to this application.
The Power Authority will soon file an application for a license to
construct the project with the Federal Energy Regulatory Commission. We
are providing a completed application to construct or modify a dam along
with the water right application, but understand it will be your agency's
policy to defer to the FERC for dam safety and engineering review of
this project to eliminate duplicative review.
The project site is presently owned by the U. S. Forest Service and
that agency will issue the necessary land use permits as part of the
FERC licensing process.
Extra copies of maps and plans are provided to aid your review. If
you desire additional details on this application, please contact Mr.
Brent Petrie. Project Manager, at our office.
Sincerely,
FOR THE EXECUTIVE DIRECTOR
,.oJ ~
" .• .o/ ,7 I ~~-;' /1 __ ~, f//'~ . ·,(· .. ·6.:..~ .o.; ........
/ /
Robert A. Mohn
Director of Engineering
Enclosure: As stated
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STATE OF ALASKA
DEPARTMENT OF NATURAL RESOURCES
DIVISION OF FOREST, LAND AND WATER MANAGEMENT
. OFFICE USE ONLY
ADL
APPLICATION FOR WATER RIGHT
Instructions: You will need (1) a map showing the location of your source of water and the area of use,
(2) a copy of your property ownership document, i.e. deed, patent, lease agreement or an easement
agreement if you do not own the property involved, (3) a copy of your driller's well log, if application
is for an existing well, (4) Statement of Beneficial Use Of Water (Fonn 10-1003A) if this is an existing
water use, and (5) Application for Permit to Construct or Modify Dam (Form 10-10 15) if you will be
constructing a dam over 10 feet high or over 50 acre feet of storage. Please type or print in ink.
I. Full legal name of Applicant(s) Alaska Power Author; ty --------------------------------------------
2. Mailing Address ___ 3_3_3_W_e_s_t_4 t_h_A_v_e_nu_e_,~S_u_i _te_3_1 ______________ _
Anchorage, Alaska 99501
Home Phone Business Phone (907) 277-7641
3. Source of Water Supply:
(a) DWell
o Drilled 0 Hand Driven 0 Dug D Other _____________ __
If existing well, attach copy of driller's well log.
If existing well, and no log, supply all"known infonnation
Total depth _____ _ Drawdown ------
Intake Depth ____ _ Screened Yes No Unknown
Static level ------------
(b) (DSurface Water
o Stream 0 River W Lake D Spring
Give geographic name (if unnamed, state so) Black Bear Lake
4.
5.
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Page 2
Water will be taken from surface water source by:
DPumping
[KJ Gravity Flow System
D Diversion (Altering a watercourse) -Attach sketch and plans giving dimensions
and specifications.
o Damming -Attach sketch and plans giving dimensions and specifications. If dam is
over 10 feet high or over 50 acre feet storage, MUST file Application for Permit to
Construct or Modify Dam (Form 1 ();.) 015).
D Other
Location of point of WITHDRAWAL, DIVERSION, or IMPOUNDMENT:
(a)
(b)
(c)
MUST attach copy of map or subdivision plat and indicate location
Fractional part NE 1/4 Section 12
Township 73 S , Range 82 E"Copper River -:cM""!"e-n..,...·d.,...i-an. (Protracted)
If applicable, Lot, Block, Subdivision; U.S. Survey No. ______________ __
Does applicant own or lease the property at point of water withdrawal and over which water is
transported? Yes 0 No []
If "Yes," MUST attach copy of ownership document (i.e. deed, patent)
If "No," MUST obtain an easement or right~f-way and supply copy. Give name, mailing
address and phone number(s) of legal owner.
Name See Page 5 Attached
Mailing Address -------------------------------
_________________________________ Zip ________ _
Home phone ___________ Business Phone ______________ _
Location of point of USE: If same as question 4, check and go to question 6. D
MUST attach copy of map or subdivision plat and indicate location.
(a) Fractional part SW 1/4 Section
---,,-,:---:~
Township 73 S ,Range 82 E ,Copper Ri ver Meridian. (Protracted)
(b) If applicable, Lot, Block, Subdivision; U.S. Survey No. __________________ _
(c) Does applicant own or lease the property at point of water use? Yes 0
If "Yes," MUST attach copy of ownership document (Le. deed, patent)
No [i]
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Page 3
If "No," MUST obtain an easement or right-of-way and supply copy. Give name, mailing
address and phone number(s) of legal owner.
Name See Page 5 Attached
Mailing Address _____________________________ _
_______________________________________________ Zip ______ ..... __
Home phone Business Phone ------------------------------------------
Type of water use and Quantity of water needed: Please fill in the attached Water Use Chart
indicating the quantity of water and months of use for each ~ of water use. Standard quantities
and definitions are provided for your convenience. If water use TsTor a Commercial/Industrial purpose
or Other Use not on the Water Use Chart, refer to question 7 .
Commercial/Industrial and Other Uses:
Explain in detail the basis for quantity of water requested. Use additional sheet of paper if needed.
Indicate type of operation including structures and methods used. Include a sketch or engineering
drawings. Enter quantity requested and months of use on attached Water Use Chart.
A maximum of 64 cfs is needed for the operation of two 3.0 MW single
nozz1e pelton wheel turbines at peak output under 1370 feet of net'head.
Date when water use began or is expected to begin 1986 . If water use is existing, rill out
Statement of Beneficial Use of Water (Form 10-1 003 .... A ... ) ..... --------
HAVE YOU ATTACHED?
o
[iJ
Deed, patent, lease, etc.
USGS or Subdivision map
Water Use Chart
D Driller's log (if existing well) o Diversion sketch and plans
W Dam sketch and plans o o o Statement of Beneficial Use of Water (Form I 0-1003A) (if existing water use)
Statements appearing herein are to the best of my knowledge true and correct.
OFFICE x,y RMI
USE
ONLY
10-102 Rev. 6/79
SIGNED Z~~ --:p,~J/
(Applicant)
Eric P. Yould
Executive Director
Location Other
check
,....
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Page 4
WATER USE CHART
Office Use Type(s) Of Standard Quantity Months of Use
SIC Use Quantities Requested From To
(Inclusive)
·8800 ( 1) Single Family Per Household
(a) Fully plumbed 500 GPD GPD
(b) Partially plumbed 250 GPD GPD
(c) Unplumbed 75 GPD GPD
6514 (2) Duplex Per Duplex 1000 GPD GPD
(3) Multi-Family Per Unit 250 GPO GPD
7011 (4) Motel, Resort Per Room 100 GPD GPD
(5) Livestock Per Head
0241 Dairy Cows 30GPD GPO
Hosing dairy barn 35 GPD GPD
0212 Range Cattle 15 GPD GPD
0272 Horses ISGPD GPO
.)214 Sheep 2 GPD GPD
Goats and Hogs 3 GPD GPD
Poultry, Rabbits, etc. J GPD GPD
Livestock Total GPD
(6) Irrigation
(Type of Crop: Per Acre
) 0.5 AFY AFY
(7) Commercial!
Incustrial 64 cfs Jan 1 Dec 30
(8) Other:
DEFINITIONS:
GPD -gallons per day AFY -acre feet per year CFS -cubic feet per second
(I) SINGLE F AMIL Y -Water use necessary for a single household and the irrigation of up to
10,000 sq. ft. of yard and garden.
(a) Fully plumbed -Water piped into the residence for domestic uses. Hot water ht'ater
and water flush toilet included.
(b) Partially plumbed -Water piped into residence for limited domestic uses. Generally
no hot water heater and no water flush toilet included. ---------------
(c) Unplumbed -No water piped into the residence. Water is hand carried for limited
domestic use. -----
(2) DUPLEX -Water use necessary for two single households and the irrigation of up to 20,000 sq.
ft. of yard and garden.
(3) MULTI·FAMILY -Water use necessary for three or more households. Apartment units
included.
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Black Bear Lake Hydroelectric Project
Water Right Application
Page 5
Item 4c: Property owner at the point of diversion and impoundment is:
U. S. Forest Service
Tongass National Forest
Ketchikan Area
Federal Building
Ketchikan, Alaska 99901
Attn: Ed Johnson
Office phone: (907) 255-3101
This land is also within an area withdrawn for selection by:
Klawock Heenya Corporation
P.O. Box 25
Klawock, Alaska 99925
Attn: Mr. Leonard Kato, President
Office phone: (907) 755-2270
This land is also a secondary selection of
Sea1aska Corporation
One Sea1aska Plaza
Juneau, Alaska 99801
Attn: Robert Loescher
Office phone: (907) 586-1212
Item 5 c: Property owner at point of use is:
U. S. Forest Service
Tongas National Forest
Ketchikan Area
Federal Building
Ketchikan, Alaska 99901
Attn: Ed Johnson
Office phone: (907) 255-3101
This land is also within an area withdrawn for selection by:
Klawock Heenya Corporation
P.O. Box 25
Klawock, Alaska 99925
Attn: Mr. Leonard Kato, President
Office phone: (907) 755-2270
This land is also a secondary selection of
Sea1aska Corporation
One Sealaska Plaza
Juneau, Alaska 99801
Attn: Robert Loescher
Office phone: (907) 586-1212
TABLE OF SIGNIFICANT DATA
BLACK BEAR LAKE HYDROELECTRIC PROJECT
RESERVOIR
water Surface Elevation, ft above mean sea level (msl)
Under Probable Maximum Flood 1721
1715
1685
Normal Maximum
Minimum
Tailwater Elevation, ft msl
Surface Area at Normal Max. El., acres
Estimated Usable Storage, ac-ft
Type of Regulation
HYDROLOGY
Drainage Area, sq mi
Avg. Annual Runoff, cfs/mi 2
streamflow, cfs
Maximum Monthly
Average Annual
Minimum Monthly
DAM
Type
Maximum Height, ft
Crest Elevation, ft msl
Crest Length, ft
Dam Volume, cy
SPILLWAY
Type
Crest Elevation, ft msl
Width, ft
Design Discharge, cfs
WATER CONDUCTOR
Type
Diameter, ft
Length, ft
Shell Thickness, in.
Steel
Penstock
4.0
294
5/16
-i-
253
241
6850
Seasonal
1.82
14.3
78.0
26.0
0.3
Concrete Gravity
53
1723
368
6400
Ungated Concrete Ogee
1715
30
1680
Concrete
Shaft
4.0
1296
Steel
Penstock
2.5
2790
11/16-3/4
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TABLE OF SIGNIFICANT DATA (Continued)
POWERSTATION
Number of Units
Turbine Type
Rated Net Head, ft
Generator Unit Rating, kW
POWER AND ENERGY
Installed Capacity, kw
Firm Capacity, kW
Avg. Annual Energy Generation, MWh
Avg. Plant Factor %
COSTS AND ECONOMICS
construction Cost, $x10 6
unit Cost, $/kW inst
B/C Ratio 3%, with 3.5~ fuel escalation
Project Funding Requirements, $x10 6
-ii-
2
Single Nozzle Impulse
1370
3000
6000
4000
23700
45
28.0
4666
3.32
39.9
DEPARTMENT OF NATURAL I'ESOUI'CES
DIVISION OF FOREST, LAND AND WATER IMNAGEMENT
October 21, 1981
Robert A. Mohn
Director of Engineering
Alaska Power Authority
334 W. Fifth Avenue
Anchorage, Alaska 99501
Dear Mr. Mohn:
lAY S. HAMMOND, GOYERNOR
Pouch 7-005
Anchorage, Alaska 99510
l~Q7J fl.6-:2653 ~m~bX~,
'R1I1tKI.XX~X)itXn:m
I am in receipt of your "Application to Construct or Modify a Dam"
for the Black Bear Lake Hydroelectric Project on Prince of Wales Island
near Klawock. Prior to issuing the permit, this office must be assured
that the dam will not create a public safety hazard. A certification to
this effect after use of state-of-the-art techniques that analyze the
design and construction, as well as the~ proposed operation and
maintenance schedules of the dam will be acceptable. It is understood
that the FERC will be performing a dam safety and engineering review
of the project. This office will accept a dam safety certification
by the FERC in any of the four areas mentioned above. For those areas
not so done by the FERC, we will review the work done by the applicant
such that this office may certify to the dam's safety.
As the project develops, please send to this office, dam safety
certifications by the FERC, or the appropriate documents allowing
such to be made.
Sincerely,
THEODORE G. SMITH
Di rector
~ BY: PAUL JAN Civil Engineer
Water Management Section
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STATE OF ALASKA
DEPARTMENT OF NATURAL RESOURCES
DIVISION OF FOREST, LAND AND WATER MANAGEMENT
OFFICE
ADL
APPLICATION FOR PERMIT TO CONSTRUCT OR MODIFY A DAM
1llis applicatiun involves in 110 way tltt, right to appropri"tc water. To secure the right to appropriall'
wa ler, applk;1 tion should Iw made tot he Director Oil anot Ill'r rOml wh it'll w ill hl~ rll rn ishl'd 111'1111
n~qllest.
Namc of Applicant (type or print) Alaska Power Authority
Mlliling Address 333 H. 4th Avenue, Suite 31 Telephone 907-277-7641
The applic:mt hereby makes application for approval of the plans and spccifications for the
.... Co""n~s:';'t"-'-r--"'u ... c""'t ..... i :"!'onu...-. ___ --:---:-,-----;-:------,-:---:-_o f B 1 a ck BeQL
(Construction, reconstruction, nlll'ration) (Name of dam)
Dam . ----
Name of Owner Alaska Power Authori ty
MailinJ! Address 333.lie.s.:L4th Avenua. Suite 31 •. .Jln.c.hor.ag.e~as.kD--~ ____ .. _
If lllL' owncr is a corporation, give name and hm.iness address or presidl'nl alld secretary
Charles Conway, Chairman, Board of Directors
Ene P. YPula, Exeeubve Dlreetor, Alaska Power Authority
333 W. 4th Avenue, Suite 31. Anchorage, Alaska 99501
Applicant is acting for the own('r in the legal capacity of
(Writkn authorization from the owner is required).
Source of watl;r supply Bl ack Bear Lake
(Creek, stream, lake)
which is all upstrctllll trihl/wry of or to 81 ack Lake
-A-:-g-e-n-t. I.~s<;l'e, Trustee. ctc.
(River or watcrbody) ---
5. Location of dam is NE 1/4. Section 12 Township 7_3S __ Rangc __ B_2E __
Copper River
Meridian.
10-1015 (,/80
6. Reservoir is _X __ onstream offstream, and will be used for (irrigation, ----
recreation, power, mining, etc.), ___ .:...:H'.l...y.!:.d.:....ro~e~l.!.,;e:::..;c:::...t::..:r--'i~c::.......:..P-"o'-"wc.=e.!...r-_---_--___ _
(7.) Description and dimensions of dam (if for alteration work, give data for the altered dam. see the
attached sketch for a description of dimensional terms).
(~. )
(<). )
a.
b.
c.
d.
Type of dam (check appropriate boxes)
Dearthfill
Drockfill
o timber crib Dconcrete arch Osheet-pile /iJconcrctc gravity o other (please describe) ________ _
Please attach a sketch which depicts the zonation and placement of material in an earthfil1 or
rockfill dam.
Length of crest 368. -------------------------------ft.
Crest wid th 6 -~--------~~--------------ft.
cu. yds. A 1Il Oll n t 0 f materia lin d .. 1ll __ -lo6'-',...:4L\oO/..loO!..-______ _
fl. Height, streambed to crest 43 -----~-----------------
31 ft. f. Height, foundation to spillway cn~st ----~~---------
g. Freeboard at maximum design spill 2.2 -------'~~---------ft.
h. Crest elevation __ 1:....:7:....:2:....:3:....:.:-0:...-.-_____ ft. above Mean Sea Level (if known)
i. D~scrjbc the foundation materials (i.e., gravel, sand, shale, granite, etc.) graywacke, di ori te
J. What is the depth to b~drock, ifknown varies from 3 to 35 ft.
Additional information for earth or rockfill dams (see attached sketch for a description of
djlll~nsional terms).
;I. Sf () pc 1I ps lrca IlI _____ -'Nu../u A:l....... ____ _
h. Slope downstream N/A .----------------
c. llpstrealll facing (rock, riprap, concrete, ctc), ___ N/A
Spillw;IY lit'scription (lYPl" capa,'ity, de.) Uncontrolled concrete ogee; maximum design
_. ____ gJ.sch~rSl..e of 1680 ~0_ @ 58 feet of head ____ ... _______________ ~
(JOJ Illkt dl.'scriplioll (lype, capacity, etc.) Multiport concrete intake structure with
automatically operated intake gates.
( 1) . Gated 6" 0" d,'ameter 1, Outlet de~crjrlion (type, capacity, etc.) '------
__ eme.r.gency out 1 et co~du_~!_. _____ _ '-----------.-----~-------.-.. --------
('olll,,,1 v;llves lIype. llrsaiplioll. de.) -48" 0 butterfJl .. va~~ ___ . __ . _____ .. __
2 -14" 0 gate valves; 2 -14" 0 needle valves
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1 i ve
RCl'l'rvoir capacily ~6.=..8.=..50~ ___ acre fecI. StoT;J~e pool area al ll1aXimUIII spillway kvel ..
__ 2:.4-'-.7'--__ acres.
14. Js clam to be built in permafrost area'? Yes ___ No X If the answer is yes, please complete
the following:
a . At what depth does the permafrost occur, if known __________ ft. ..
b . Do you have plans to prevent the permafrost from thawing, if so" describe briefly ..
•
(IS.) What is the expected life of thl' strudure 100 yrs. ----"-----
. (I (I.) If till' slrurtuTl' is \)l~ing designed hy :llll'nginecring firm, please provide:
Firm \ Naml' Harza Engi neeri ng Company ..
~1Jilillc Address 150 South Wacker Dri ve
-Chl cago, II 11 nOl S 60605
till! 17. If til hl' built under Federal slIlwrvisinn. which agency has jurisdiction? Federal Energy ReglJktory
til Commission
.. I H. Ilcsi)!lIall'd operalor of dam:
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N:lIIII' Alaska Power Authority --=---
Address 333 West 4th A~enu~L.?~ite 31, Anchorage, I'hOl1l' 907-277-7641
Alaska 99501
Availability (24 hour call, weekly, seasonally, de.) Pl ant will ~e operated by remote control from
Kla\'Iock. Local .operator name will be provided when construction is compJ.ete and plaflt
DOl'S ;1 waler ri~llt ior this dalll and illlpounclmcnt exist or has one been applied for!OCXl }tl'S Uno is opera-
II' Sill'll waleI' rights have been applied for or sccuil'd, pkasl' !!ivl' Alaska Division of Forl'sl, Lalld and tional.
Watn Managelllent ADL serial numbcr, applicant, permittee or OWlll'r name, and adurcss .
Applicant: Alaska Power Authority
333 West 4th Avenue, Suite 31
Anchorage, Alaska 99501
(:'0.) I'Lh\SF AT/"ACII COPIES OF PLANS, DRAWINGS, lirl-X;4X'l~OCQ)(~ ~~U~~Ut¥l)§ttIUXXlX
X~MX~~I~X~~~XX~XKK~~~XXXXX
Signed
Director
3
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BLACK BEAR LAKE HYDROELECTRIC PROJECT
FERC NO. 5715
EXHIBIT E
STATEMENT CONCERNING THE NATURE, EXTENT
AND OWNERSHIP OF WATER RIGHTS
ALASKA POWER AUTHORITY
ANCHORAGE, ALASKA
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Plack Bear lake -Exhibits A-V
Exhiliit E
EXHIBIT F.
STA'I'El-1ENT CONCERNING THE
NATURE, EXTENI' AND a-mERSHIP
OF ~JATER RIGHTS
There are no other appropriations of the water which is proposed for use
in the Project.
An application for the wa.ter rights related to the Project has been
filed by the Applicant with the State of Alaska, Department of Natural
Resources , Division of Forest, Land and Water ~1anagement (see Exhilii t
D). The Applicant has no reason to believe that a pennit and
certificate will not be iSSUed. ~'hen the certificRt.e is received a
certified copy and additional uncertified copies will be submitted.
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BLACK BEAR LAKE HYDROELECTRIC PROJECT
FERC NO. 5715
EXHIBIT F
STATEMENT CONCERNING OWNERSHIP OF LANDS TO
BE UTILIZED IN THE PROPOSED DEVELOPMENT
ALASKA POWER AUTHORITY
ANCHORAGE, ALASKA
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Black Bear Lake -Exhibits A-v
Exhibit F
EXHIBIT F
STATEMENT C,.'Q..lCERNING CMNERSHIP OF
lANDS 'IO BE t1I'ILIZED IN THE DEVEWPMENT
Reference is made to Exhibit K of this application, which shows on five
maps the Project lavout and the ONnership of land covered by the
Project.
The Project dam, reservoir, and pav.7erhouse are entirely on lands owned
by the u. S. Government under the jurisdiction of the U. S. Depart::nEnt
of Agriculture, Forest Service. In addition the dam and ]XJWerhouse are
on parcels of federal land which constitute areas available for
selection or secondary selections of Kla~k Heenya Corporation and
Sealaska Regional Corporation under the Alaska Native Claims Settlement
Act. These lands are in the Tongass National Forest.
The transmission line to the Kla~k substation and then to Hydaburg
crosses private lands owned by Sealaska, the Native Regional
Corporation; Klawock Heenya, the village corporation of Klawock; and
Haida Corporation, the village corporation of Hydaburg as well as
federal lands under the jurisdiction of the Forest Service.
Acquisition of federal lands for project construction and. transmission
line right-of-way will be fran the U. S. Forest Service based upon final
alignments determined by review of this application. Acguisi tion of
lands from private parties will proceed under a variety of nechanisms
available to the Power Authority such as penni t., lease, purchase, or
condemnation.
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BLACK BEAR LAKE HYDROELECTRIC PROJECT
FERC NO. 5715
EXHIBIT G
STATEMENT OF THE APPLICANT'S FINANCIAL ABILITY
AND PROPOSED METHOD OF FINANCING THE CONSTRUCTION
ALASKA POWER AUTHORITY
ANCHORAGE, ALASKA
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-
Black Bear rake
EXhibit G
EXHIBIT G
STATEMENT OF THE APPLICANl" S
FINANCIAL STANDIN:; AND '!HE PmPa3EJ)
The Applicant is -a public corporation of the State of Alaska in the
Depar\::nlent of Ccmnerce and Ecx>nanic Develqmmt but with separate and
independent legal existence. The Applicant is atpCMered to construct,
acquire, finance, and operate power production facilities. In addition
to its other powers, the Applicant can issue l:x::>rrls to carry out its
corporate ptJrIX>ses, and enter into contracts for the sale or
transmission of power for the security of any bonds issued to finance
a project.
The Applicant's sources of financing will be direct State of Alaska
appropriations or loans to the Applicant, loans fran the Rural
Electrification Mninistration, and/or project revenue bonds issued
by the Applicant. The State of Alaska's current hydroelectric project
funding program may provide for full funding of the capital cost of
the project by direct state appropriations to the AWlicant. The
Applicant received $400 million of funding in 1981 fran the State for
other projects. If the State of Alaska does not directly furrl the full
costs of the project, the Applicant expects that at least an estimated
25% of the project cost will be provided. by state appropriatiops, 15%
by RFA loans, and 60% by proceeds of the sale of revenue bonds. Repayment
of the State appropriation or loan by the Applicant will be subordinate
Black Bear Lake
EXhibit G
to the paynent of revenue bond debt service. The Applicant will also
explore the availability of State guarantees of the Applicant's revenue
bonds issued to finance the project as an alternative to state
appropriations and/or loans.
Absent state guarantees, the revenues of the Project will be the only
basis for security of the state loans and the revenue bonds issued for
the project. Power sales contracts with the Tlingit-Haida Regional
Electric Authority serving the City of Klawock, and the Alaska PcMer and
Telephone Carpany serving the City of Craig and the City of Hydaburg,
will be necessary to guarantee payrrent of debt service and estimated
costs.
The Applicant anticipates that eleCtric loads will continue to increase
at a steady rate and that the Project's power output will be fully
utilized wi thin about 6 years of the initial operation, based on the
assurrption that camercial operation of the Project will begin jn 1986.
The Applicant is empowered to wholesale power to utilities and major
industrial users under power sales contracts at rates consistent to ITEet
its costs. The costs will include charges sufficient to cover the cost
of Project debt service including both principal and interest, a debt
service coverage factor necessary to market the bonds, financing costs,
and the cost of operation and maintenance of the Project facilities.
The following attachItent regarding the Applicant's financial standing is
included in this EXhibit:
I
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Black Bear Lake
EKhibit G
1. A copy of the Alaska Power Authority Financial Stat.ements for
the year ending June 30, 1981.
ALASKA POWER AUTHORITY
FINANCIAL STATEMENTS
JUNE 30, 1981
~ce \I Vaterhouse &. Co
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nee ~. aterhouse
To the Board of Directors
Alaska Power Authority
101 WEST BENSON BOULEVARD
ANCHORAGE, AK 99503
907279-1424
October 2, 1981
We have examined the balance sheet of the Alaska Power
Authority as of June 30, 1981, and the related statements of
revenues and expenses, changes in contributed capital and changes
in financial position for the year then ended. Our examination
was made in accordance with generally accepted auditing standards
and accordingly included such tests of the accounting records and
such other auditing procedures as we considered necessary in the
circumstances .
As discussed in Note 2, the Authority has kept its records
and has prepared its financial statements for previous years on
the basis of expenditures and encumbrances with no recognition
having been accorded accounts receivable, accounts payable or
accrued expenses. At the beginning of the current year the
Authority adopted the accrual basis of accounting. Although
appropriate adjustments have been made to contributed capital as
of the beginning of the year, it was not practicable to determine
what adjustments would be necessary in the financial statements
of the preceding year to restate results of operations and
changes in financial position in conformity with the accounting
principles used in the current year .
In our opinion, the accompanying financial statements
present fairly the financial position of Alaska Power Authority
as of June 30, 1981 and the results of its operations and the
changes in its financial position for the year then ended, in
conformity with generally accepted accounting principles.
CURRENT ASSETS:
ASSETS
ALASKA POWER AUTHORITY
BALANCE SHEET
Jm~E 30, 1981
Due from State of Alaska Treasury
Accrued interest receivable -
Power project loans
Note receivable
Total current assets
PROPERTY, PLANT AND EQUIPMENT, at cost net
of accumulated depreciation (Note 4)
CONSTRUCTION WORK IN PROGRESS (Note 1)
OTHER ASSETS:
Deferred project costs (Note 1)
Note receivable (Note 5)
Power project loans receivable, (including
accrued interest of $1,084,412) (Note 5)
LIABILITIES AND CONTRIBUTED CAPITAL
CURRENT LIABILITIES:
Accounts payable
Accrued wages
Accrued interest payable -
Power project loans
Note payable
Total current liabilities
NOTE PAYABLE (Note 5)
POWER PROJECT LOAl~S, payable to
State of Alaska (including accrued
interest of $1,084,412) (Note 5)
Total liabilities
CONTRIBUTED CAPITAL
C011HITMENTS (Note 6)
$ 9,874,945
95,587
423,836
10,394,368
1,641,196
2,651,090
22,141,920
35,000,000
22,023,068
79,164,988
$93.851.642
$ 3,409,237
15,708
95,587
423,836
3,944,368
35,000,000
28,473,068
67,417,436
26,434,206
$93.851.642
See accompanying notes to financial statements
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Revenues:
ALASKA POWER AUTHORITY
STATEMENT OF REVENUES AND EXPENSES
YEAR ENDED JUNE 30, 1981
Power cost assistance
Operational funding
Interest Income
Expenses:
General and administrative
Power cost assistance
Depreciation
Interest
Net loss (Note 4)
$2,287,735
478,295
1,387,500
$
4,153,530
478,295
2,287,735
4,442
1,387,500
4,157,972
(4.442)
See accompanying notes to financial statements
3
ALASKA PelVER AUTHORITY
STATE~fENT OF CHAUGES IN FINANCIAL POSITION
YEAR ENDED JUNE 30, 1981
Sources of Working Capital:
From Operations -
Net loss
Add items not requiring working capital -
Depreciation on operating assets
Depreciation capitalized as deferred
project costs
Working capital provided by operations
Proceeds from issuance of notes
Repayments of power project loans receivable
Contributions of capital from State of Alaska
Power project loans received from State
Receipt of pass-through grants
Increase in accrued interest payable on
power project loans
Uses of Working Capital:
Loans made - .
Power project loans
City of Ketchikan
Increase in deferred project costs -
Additions
Transfers to construction work in progress
Capitalized depreciation
Increase in construction work in progress -
Additions
Transfers from deferred project costs
Repayments of power project loans payable
Disbursement of pass-through gra:1ts
Acquisition of property, plant and equipment
Increase in accrued interest receivable on
power project loans
Increase in working capital
Changes in Components of Working Capital:
Increase in current assets -
Due from State of Alaska Treasury
Accrued interest receivable
Increase in current liabilities -
Accounts payable
Accrued wages
Accrued interest payable
Net increase in working capital
$ (4,442)
4,442
369,400
369,400
35,000,000
464,200
20,072,906
21,075,641
268,484
821,380
78,072,011
14,625,641
35,000,000
17,432,442
(227,238)
369,400
2,423,852
227,238
464,200
268,484
216,612
821,380
71,622,011
S 6,450,000
$ 8,387,355
509,975
8,897,330
1,921,647
15,708
509,975
2,447,330
S 6,450,000
See accompanying notes to financial statements
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ALASKA pm-JER AUTHORITY
STATE~mNT OF CHANGES IN CONTRIBUTED CAPITAL
YEAR ENDED JUl~E 30, 1981
Contributed Retained
CaEital Earnings
Balance, July I, 1980 $ 6,365,742 $ -0-
Contributions from the
State of Alaska 20,072,906
Net loss transferred from
operations (4,442)
Depreciation on contributed
assets (4,442) 4,442
Balance, June 30, 1981 ~2614341206 ~ -0-
See accompanying notes to financial statements
5
Total
$ 6,365,742
20,072,906
(4,442)
~2614J41206
ALASKA POWER AUTHORITY
NOTES TO FINANCIAL STATEMENTS
JUNE 30, 1981
NOTE 1 -DESCRIPTION OF OPERATIONS AND SUMMARY OF SIGNIFICAl~T
ACCOUNTING POLICIES:
Operations -
The Alaska Power Authority (the Authority) is a public
corporation of the State of Alaska in the Department of Commerce
and Economic Development but with separate and independent legal
existence. The Board of Directors of the Authority consists of
the Director of the Division of Budget and Management, three
commissioners of principal executive departments appointed by the
governor and three public members appointed by the governor and
confirmed by the legislature of the State of Alaska.
The Authority was established to promote, develop and
advance the general prosperity and economic welfare of the people
of Alaska by providing a means of constructing, acquiring,
financing and operating power production facilities. Such
facilities may operate on fossil fuels, waste energy conservation
and renewable energy resources, including but not limited to
hydroelectric power, wind, biomass, geothermal, tidal or solar
energy.
The Authority proposes to issue revenue bonds, which in
certain instances may require the approval of the legislature, to
finance proposed construction to the extent considered necessary.
The principal and interest due on such bonds will be determined
on a project by project basis by the Legislature and the Authority
in accordance with Alaska Statute 44.83, under which the Authority
was created.
Basis of Accounting -
The financial activities of the Authority are partially
restricted by requirements of the Alaska State Legislature and
are recorded in various specific purpose funds and accounts in
accordance with authorizing legislation or as necessitated by
appropriation requirements. Financial activities and resulting
account balances which are not so restricted are recorded in the
Operating Fund. The Authority's funds are considered to be
enterprise funds for financial reporting purposes and are
presented on a combined basis.
Property, Plant and Equipment -
Plant and equipment are stated at cost and depreciated on a
straight-line basis over estimated useful lives. A half year's
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depreciation is taken in the year of acquisition
additions other than power generating equipment.
repairs and maintenance are expensed as incurred
betterments are capitalized .
Deferred Project Costs -
for fixed asset
Ordinary
whereas major
Costs of feasibility studies performed in connection with
potential construction projects which are expected to benefit
future operations or result in construction of a power generating
facility are deferred to future periods of benefit. Deferred
costs related to feasible projects are reclassified to construc-
tion work in progress at the onset of the design and construction
phase. Deferred costs related to abandoned projects will be
expensed in the period of abandonment.
NOTE 2 -CHANGE IN PP~SENTATION:
During the year, management determined that the Authority
should prepare its financial statements in accordance with
generally accepted accounting principles and the financial
activities of the Authority in its entirety should be accounted
for as an enterprise fund of the State of Alaska. Accordingly,
the financial statements for the year ended June 30, 1981 have
been prepared on this basis of accounting.
For the year ended June 30, 1980, the Authority prepared its
financial statements on the basis of expenditures and encumbrances
recorded in the accounting records under the State of Alaska's
budgetary guidelines. Under these guidelines, expenditures are
recorded when paid except that expenditures paid during July and
August relating to the previous fiscal year may be properly
accounted for as expenditures of the previous fiscal period.
Further, the Authority recorded as expenditures Operating Fund
encumbrances outstanding at the end of the fiscal year which are
properly allocable to that fiscal year. For years prior to 1980,
the Authority had prepared its financial statements on the basis
of cash receipts and disbursements during the fiscal year.
The Authority had not prepared balance sheets or statements
of changes in financial position in prior years as the only
operations during the years ended June 30, 1980 and 1979 consisted
of acquiring office space, hiring personnel and contracting for
certain engineering studies in connection with potential
construction projects.
NOTE 3 -APPROPRIATIONS FROM THE STATE OF ALASKA:
Certain of the Authority's activities are financed through
appropriations from the State of Alaska to the Authority's
various funds as described below:
7
Operating Fund -
The Operating Fund accounts for appropriations from the
State which are to be expended by the Authority for administrative
and operating costs. Any appropriations unexpended or unencumbered
at the end of a fiscal year lapse into the State's General Fund.
Capital Projects Fund -
The Capital Projects Fund accounts for appropriations from
the State which are to be expended by the Authority on construction
projects or related studies; such costs are accounted for in
accordance with the policy described in Note 1. Capital projects
appropriations are generally expended over the life of the
related projects and unexpended amounts do not lapse into the
State's General Fund until the project is completed.
Effective August 4, 1981, the legislature of the State of
Alaska established the Power Development Fund of the Authority.
The Power Development Fund will account for appropriations for
the energy program for the State of Alaska to be expended by the
Authority for reconnaissance and feasibility studies, power
project finance plans, power project construction, debt service
and power project operating costs. Accordingly, effective
August 4, 1981 and thereafter all activities and balances of the
Capital Projects Fund will be reflected in the Power Development
Fund.
Power Project Loan Fund -
The Power Project Loan Fund accounts for appropriations from
the State which are to be expended by the Authority in the form
of loans for feasibility studies, design and construction of
power projects consistent with the Authority's mandate. These
funds are to be expended at the direction of the Authority's
Board of Directors or by legislative mandate and do not lapse at
the end of the fiscal year.
Prior to July I, 1980, repayments on loans reverted to the
fund and were available for expenditure at the direction of the
Authority's Board of Directors. Subsequent to July I, 1980, all
power project loan earnings and repayments (on loans not
redesignated as grants) will revert to the State of Alaska
General Fund. The majority of the loans are repayable over a
twenty year period commencing between fiscal years 1988 and 1991;
accordingly, the loans have been classified as long-term.
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Grant Fund -
The Grant Fund accounts for appropriations from the State
which are to be expended by the Authority for energy related
grants. These funds are to be expended at the direction of the
Authority's Board of Directors or legislative mandate and do not
lapse at the end of the fiscal year .
Power Cost Assistance Fund -
The Power Cost Assistance Fund accounts for appropriations
and expenditures for financial assistance to eligible electrical
utilities in the State of Alaska. The fund is composed of money
appropriated for the purpose of providing power cost assistance
to electric utilities to reduce the cost of electric energy to
the consumer.
The Power Cost Assistance Fund was established by legislative
action effective August 4, 1981; however, as a program of the
same nature was in effect for the year ended June 30, 1981, the
activities of that program have been reflected in the Power Cost
Assistance Fund for purposes of financial statement presentation.
Any appropriations unexpended or unencumbered at the end of
fiscal year 1981 lapse into the State's General Fund .
Rural Electrification Revolving Loan Fund -
The Rural Electrification Revolving Loan Fund was established
effective August 4, 1981 to account for appropriations made to
the fund and loans made by the fund. The Authority will make
loans from the fund to electric utilities for the purpose of
extending new electric service into an area of the State that an
electric utility may serve under a certificate of public
convenience and necessity issued by the APUC .
NOTE 4 -PROPERTY, PLANT AND EQUIPMENT:
The following summarizes the property, plant and equipment
at June 30, 1981: Useful Lives
Camp buildings
Machinery and equipment
Furniture and fixtures
Less: Accumulated depreciation
(Years)
5
5
7-10
$1,027,221
898,682
89,135
2,015,038
373,842
$1.641,196
9
Depreciation on property, plant and equipment related to
specific project activities is charged to project costs.
Depreciation on contributed assets not related to specific
project activities is charged to operations. Such depreciation
amounted to $4,442 for the year ended June 30, 1981 and is
reflected in the resulting net loss from operations and as a
reduction of contributed capital in the accompanying statements.
NOTE 5 -NOTES RECEIVABLE AND PAYABLE:
On May 28, 1981 the Authority entered into agreements with a
consortium of banks (the Lenders) and the City of Ketchikan (the
City) whereby the Authority borrowed $35,000,000, as evidenced by
General Obligation Bonds, Series 1981, and in turn loaned the
monies to the City, as evidenced by Municipal Utilities Revenue
Bond Anticipation Note, 1981.
The term loan from the Lenders is secured by the general
obligation of the Authority and by all proceeds of any refunding
bonds and the note and loan agreement between the Authority and
the City. The loan to the City is secured by proceeds of any
Ketchikan Public Utility refunding bonds, certain revenues and
amounts in the Utility's Revenue Fund and all monies in the
City's Swan Lake Construction Fund.
Other terms of the note payable to the Lenders and note
receivable from the City which mature May 28, 1984 are identical
and require semiannual payments of interest on November 30 and
May 31. Interest is calculated at a daily rate determined as
follows:
The rate is 65% of the Morgan Guaranty Trust Company prime
rate (the Formula Rate) not to exceed 13%, or if the Formula Rate
is less than 13% during any interest period then the interest
payment will be the sum of (i) the amount due based on the
Formula Rate, plus (ii) an Interest Differential (described
below); provided the sum of the rates determined in (i) plus (ii)
does not exceed a 13% effective interest rate. The Interest
Differential is the amount of interest that would have been paid
(if a 13% ceiling did not exist) when the Formula Rate exceeded
13%, less any interest actually paid to date.
Pursuant to the Power Project Loan Fund program (formerly
the Power Project Revolving Loan Fund) the Authority has loans
receivable at June 30, 1981 from various utilities as set forth
below:
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Date Rate
of of Accrued
Loan Borrower Interest PrinciEa1 Interest Total
Alaska Electric Light
and Power -
4/78 Improvements 6.5% $ 483,000 $ 6,536 $ 489,536
10/80 Improvements 8.6% 1,000,000 59,847 1,059,847
3/81 Upper Salmon Creek 7.0'70 200.000 4.450 204.450
Kodiak Electric
Association (1) -
11/78 Terror Lake 5.0% 100,000-13.811 113,811
8/79 Terror Lake 5.0% 2.000,000 190.832 2,190.832
10/79 Mennonite Creek 7.0% 89,198 3,121 92.319
8/80 Port Lions 7.0% 205.677 7.199 212.876
8/80 Terror Lake 5.0% 1,050,000 48,218 1.098,218
Ketchikan Public
Utilities (1) -
11/78 Swan Lake 5.0% 200,000 27.375 227,375
12/78 Swan Lake 5.0% 135.000 17.747 152.747
7/79 Swan Lake 5.0% 3.115,000 289.414 3.404.414
6/80 Swan Lake 5.0% 11.550.000(2) 455.958 12,005.958
Thomas Bay Power
Commission (1) -
12/78 Tyee Lake 5.0% 120.000 15.769 135,769
7/79 Tyee Lake 5.0% 60.000 6.132 66.132
8/80 City of King Cove 7.0% 205.140 7.180 212.320
9/80 Akutan 7.0% 125,641 7.254 132.895
10/80 Iliamna-New Ha1en 8.6% 300 1 000 19,156 319,156
$20.938.656(2) $1.179.999 $22.118.655
(1) Redesignated as grants effective August 4, 1981.
(2) Excludes undisbursed loan proceeds of $6,450.000.
Each of the loans was made pursuant to legislative direction
and all principal and interest repayments revert directly to the
State of Alaska General Fund. Accordingly, the Authority has
recorded payables to the State of Alaska equal to the outstanding
balance of Power Project Loan Fund loans, interest receivable and
available undisbursed loan proceeds of $6,450,000. Effective
August 4, 1981 approximately $18,624,875 of the loans outstanding
at June 30, 1981 were redesignated as grants.
NOTE 6 -COMMITMENTS AND UNEXPENDED APPROPRIATIONS:
The Authority leases its office facilities and certain
equipment for periods expiring between June, 1982 and August,
1984 with aggregate annual rental payments as set forth below:
11
Year Ending June 30,
1982
1983
1984
1985
$131,569
$109,920
$112,875
$9,450
Following is a summary of unexpended appropriations by fund
as of June 30, 1981:
Power Project Loan Fund
Capital Projects Fund
Grant Fund
$10,590,359
$27,178,790
$748,516
NOTE 7 -EVENTS SUBSEQUENT TO JUNE 30, 1981:
Effective August 4, 1981, the legislature of the State of
Alaska appropriated $397,785,000 and ~lOO,OOO,OOO, and interest
earned on the investment of, certain of the appropriations, to the
Authority to be utilized for projects, assistance, loans and
grants through the Authority's various funds for fiscal years
1982 and 1983, respectively.
Additionally, effective August 4, 1981, the Rural Electri-
fication Revolving Loan, the Power Cost Assistance and the Power
Development Funds of the Authority were established as discussed
in Note 3 above.
Effective August 4, 1981, legislation was passed which
redesignated $18,624,875 of the June 30, 1981 balance of Power
Project Loan Fund loans as grants subject to the newly
established Power Development Fund established on the same date.
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BLACK BEAR LAKE HYDROELECTRIC PROJECT
FERC NO. 5715
EXHIBIT H
STATEMENT OF THE PROPOSED
OPERATION OF THE PROJECT WORKS
ALASKA POWER AUTHORITY
ANCHORAGE, ALASKA
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BLACK BEAR L~KF HYDROFLECTRIC PROJECT
EXHIBIT H
Project setting
Streamflows
Project operation
Navigation
Table of Contents
Irrigation, Municipal and Domestic water supply
Recreation
Flood Control
Fish and Wildlife
Water Quality
Utilization of the Resources
List ot Tables
H-1 Average Monthly Flows
H-2 Average Monthly Evaporation Losses
List of Figures
B-1 Synthesized Average Monthly Flow
H-2 Flow ~eleases
B-3 Reservoir Operation
List ot ~endices
Appendix A Hydrology
H-i
Page
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H-4
H-4
H-4
H-5
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H-5
H-2
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BLACK BEAR I,AKE HYDROELECTRIC PROJFCT
EXHIBIT H
STATEMENT OF PRCPOSED OPERATION OF PROJECT WORKS
Project Setting
The Black Bear Lake Project is located on Prince of Wales
Island eight miles east of Rlawock. ~he Lake is at
elevation 1,b80 feet, and thE total drainage area for the Black Bear
Lake Project, including the lake, is 1.82 square miles. The
drainage basin is about two miles long with the lake extending about
70 percent of this length. The mean basin elevation of 2,410 feet
makes Black Bear Lake one of the highest baSins on Prince of Wales
Island. Black Bear Creek leaves Elack Bear Lake and drops
1,400 feet by a series of falls and rapids within O.b miles. The
stream trends in a northwesterly direction to Black Lake, 1.7 miles
downstream of Black Bear Lake and about 1,bOO feet lower in
elevation. Exhibit J shows a general map of the area.
A concrete gravity dam with a spillway crest at
will be located at the outlet of Black Bear Lake.
raise the lake level by 35 teet, and will
b,a50 acre-feet of active storage. rhe surface area
will increase trom its current estimated size of 212
241 acres at Elevation 1715.
Streamflows
1715 Elevation
The dam
provide
of the
will
about
lake
acres to about
~h€ hydrology report for the Black Bear Lake Project is
presented in Appendix A of this Exhibit. Below is a summary of the
results.
The climate is humid and is typified by mild temperatures and
heavy precipitation. The nearest climatological station is
Ketchikan ~hich has a historical mean annual precipitation of
15b.Ob inches, and mean ar.nual temperature of 45.7 degrees
Farhenhei t. Based on otlier nearby gages and elevation of the lake,
the average annual runott at Black Bear lake is estimated to be
14.3 cfs per square mile. ~his represents a total mean annual
runott ot 2b cis. Since the streamflow gage at the outlet of
Black Bear Lake was installed in June 1980, other gage records were
used to synthesize monthly flow data for a period of 30 years. ~he
results are presented in Figure H-1. The estimated average monthly
flows are shown in Table B-1.
B-1
Table B-1
AVERAGE MONTHLY FLOWS
(cts)
Month
January 6.5
February 5.4
March 4.7
April 15.8
May 39.0
June 47.1
July 27.4
August 22.9
September 36.6
October 41.7
November 34.0
December 24.8
The predominance of overcast days and relativ€ly cool
temperature precludes major evaporation losses. Evaporation
virtually ceases in mid-winter when Black Bear Lake freezes over.
The nearest Weather Bureau station tor which evaporation' data are
available is located at the Juneau airport. Average annual
evaporation losses of 15.9 inches were observed at Juneau
between 1968 and 1977.
The annual evaporation IOSd at Black Bear Lake is probably less
than at Juneau because of a higher annual precipitation and lower
average annual temperature. It is estimated that the mean annual
evaporation losses in the project area would be less than eleven
inches. For Black Bear Lake, an annual Class A pa.n coefficient of
0.10 was assumed to be representative ot evaporation from a large
free-~ter surface. Averge monthly evaporation losses for
Black Bear Lake are Shown in Table H-2
H-2
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1.60
Table H-2
AVERAGE MONTHLY EVAPORATION LOSSES, BLACK BEAR LARE
June
1.82
July
1.92
(inches)
August
1.68
September
0.68
TCT~
7.70
The probable maximum tlood (PMF) was estimated using the
probable maximum precipitation (PMP) isohyetal map ot the
National Weather Service. The 12-hour PMP for the Black Bear basin
produces 9.2 inches in six hours, 18.4 inches in 24 hours, and
31.3 inches in 12 hours. The inflow to the lake was combined with
the tlow from direct precipitation on the surface of the lake to
obtain a PMF peak inflow of 4,000 cfs, and a volume of
4.250 acre-feet. The 100-year flood peak was estimated to be
1,000 cfs.
Project Operation
The operation study was carried out on a monthly basis by
simulating reservoir operation to meet forecast monthly peak and
energy demands which are presented Exhibit W, Section 8.1. A
computer program was used for the simulation, using the 30 years of
synthesized monthly flows presented in Figure H-1. A 95 percent
exceedance level was judged acceptable tor the determination of firm
power, particularly in view of the reserve generation available. In
addition, maximum and/or minimum flow releases were defined to
reduce environmental impacts during specitic months wtich are
important for salmon spawning and incubation. A detailed
description and explanation of these constraints is presented in
Exhibit ~.
The minimum allowable lake level was set at Elevation 1685 to
allow for intake submergence and tor construction of most project
features above the existing lake level. An incremental cost benefit
analysis was made to determine the maximum reservoir elevation.
Benefits were based on the alternative cost ot diesel generation.
Costs included the increm€ntal costs for the structures and
equipment due to the increase in the height of the dam and in the
installed capacity, as the reservoir level increased. For
elevations higher than Elevation 1715, the incremental benefit-cost
H-3
ratio was less than unity. As a result, Elevation 1115 was selected
as the maximum reservoir elevation tor the project. •
Based on the analysis of future load characteristics presented
in Exhibit W, Sect10n 8. 1 and environmental constraints, monthly
minimum, maximum and average flo~ releases are presented in
Figure B-2. These flow releases will occur when the project energy
output is fully utilized. Similarly, monthly reservoir elevations
were computed by the computer program tor various exceedance levels,
and are presented 1n Figure H-3. The capacities shown on this
Figure H-3 correspond to 24-hour continuous capacities. During
years ot high inflows, the reservoir will be operated near the
maximum water level. During low flow years, the reservoir will be
drawn down to the level necessary to meet environmental constraints
and energy demand. The dependable power and average energy
available is presented in Exhibit I.
Navigation
Black Rear Lake and Black Bear Creek do not support commercial
navigation. The project is not being constructed nor will be
operated tor tne purpose ot aiding or enhancing commercial
navigation.
I~~igation, Municipal and Domestic Water Supply
NO uses of the project waters are anticipated for irrigation or
water supply.
Recreation
The effects of project co~struction and operation on recreation
in the area are described in Exhibits Rand w.
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Flood Control
The Project is not designed for the purpose of flood control.
However, the storage capacity will allow some regulation. The ogee-
shaped spillway which is located centrally in the darn is designed to
pass all floods, including the probable maximum flood (P~F).
Fish and Wildlife -------~~~~~
The effects of project construction and operation on the fish
and wildlife resources in the area are described in Exhibits S
and W.
Although there is no plan to provide a dependable water supply
for a fish hatchery, the Alaska Department of Fish and Game will be
kept informed during the design phase. The necessary items could be
designed and constructed into the facilities.
Water Quality
The effect of project construction and operation on water
quality is discussed in Exhibit W.
Utilization of the Resources
The Project will fully develop and utilize the water resource in
the best public interest for power, fish, wildlife, and recreational
purposes. The darn will almost fully regulate the inflow to the lake
for energy production. The maximum head which can economically be
developed at the site is used by the Project. Exhibits I, R, S,
and W further describe the benefits of the Project.
H-5
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AVERAGE MONTHLY FLOWS (cfs) FIGURE H-1
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UCT NUV nEe JArI fEB MAH APH MAY JUN JUL AUG SEP YEAR (31) nU) (31) 01 ) (2H) (31) (30) (31) \30) (31) (3J) (30)
1 lIO.l 5S.lI h.a 10.1 . & .1 1.9 :·1 lI. & 27.& &0.7 28.4 8.2 25.9
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& 40.7 27.0 25.& 6.9 b.2 1.2 21.0 52.1 3&.3 20.8 29." '1'1.5 7 5' •• U lIl.~ 32.7 1.1 lI.3 #:1.2 11.9 '17.2 55.9 1&.9 47.9 19.5
Ii 2H.O 3q.'I 22.6 b.O 0.7 5.lI 11.5 27.7 50.5 2&.0 &.3 34.6 q '17.1 .. 47.9 Il1.l 7.5 1.0 7.!) 17 .3 33.6 15 .. 3 7.7 11.5 2&.5 10 5it.l tt2.lI 2 1 •• 1 8.'1 10.5 0.7 . 16.0 q'l." Il1.2 42.& 24.9 36.1 11 25.1 4&.1 2H.q ·9.3 0.9 8.7 13.7 55.& '19.1 23.'1 20.'1 30.'1
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2& bS.9 30.b 2l1.2 2.3 &.'1 8.6 13.0 33.3 39.5 26.2 25.9 3'1.6 27 Sq.) 42.0 4b.O 8.3 1.5 12.1 18.5 37.3 q9.9 46.1 1'1.4 .H.7
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~q "~.b 31.lI 27.7 14.3 0.3 5.3 19.6 25.0 59.1 24.7 20.0 42.1
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BLACK BEAR LAKE
HYDROELECTRIC PROJECT
ALASKA
SYNTHESIZED
AVERAGE MONTHLY FLOW
~ZA ~""O'''''I!E''''''''O COMOl ........... MA""C>< 1981 ALASKA POWER AtmtOR1TY
FLOW RELEASES
Minimum
(cfs)
January 9
February 12
March 9
April 9
May 20
June 15
July 24
August 24
September 29
October 25
November 23
December 9
Annual 9
I--tARZA ENG'NEER'NG C~NY MARCt-< 'SB1
Maximum
(cfs)
24
24
24
24
39
49
58
38
46
44
42
28
58
FIGURE H-2
Average
(cfs)
17
17
17
17
27
28
36
33
36
33
31
17
26
BLACK BEAR LAKE
HYDROELECTRIC PROJECT
ALASKA
FLOW RELEASES
ALASKA POWER AUTHORITY
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--
---------
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------..
BLACK BEAR LAKE HYDROELECTRIC PROJECT
PERC NO. 5715
EXHIBIT H
APPENDIX A
HYDROLOGY
ALASKA POWER AUTHORITY
ANCHORAGE, ALASKA
--------------------------------------
Exhibit H
Appendix A
HYDROLOGY
TABLE OF CONTENTS
Basin Description
Climate
Streamflow
Streamflow Records
Flow Synthesis for Black Bear Lake
Flow Synthesis Downstream of Black Bear Lake
Floods
Probable Maximum Flood
IOO-Year Floods
Flood Frequency Curves
Reservoir Routing for Spillway Design
Low Flow Frequency
Evaporation
Sedimentation
References
HA-i
HA-l
HA-4
HA-6
HA-6
HA-6
HA-9
HA-17
HA-17
HA-17
HA-22
HA-24
HA-26
HA-30
HA-3l
HA-33
No.
1
2
3
4
5
6
7
8
9
TABLE OF CONTENTS (Continued)
Location Map
Drainage Area Map
LIST OF PLATES
Basin Elevation vs. Runoff
Monthly Percent of Annual Runoff
Monthly Average Flow
1946-Low Flow Year
1944-Average Flow Year
1949-High Flow Year
Black Bear Lake Unit Hydrograph
10 Black Bear Lake-Probable Maximum Precipitation
and Inflow Hydrograph
11
12
13
14
15
No.
1
2
3
4
5
6
7
8
Black Bear Lake-lOa Year Precipitation and Inflow
Hydrograph
Momentary Peak Flood Frequency Curves
Spillway Design Curve
Black Bear Lake PMF Inflow and Outflow Hydrographs
7-, 14-, 30-Day Low Flows
LIST OF TABLES
Ketchikan Average Precipitation and Temperature
Area Stream Gages
Black Bear Lake Monthly Runoff Percent
Black Bear Lake Outflow Rating
Black Lake Outflow Rating
lOa-Year Flows
lOO-Year Flood Derivation
Average Monthly Evaporation Losses, Juneau Airport
HA-ii
HA-2
HA-3
HA-lO
HA-12
HA-13
HA-14
HA-15
HA-16
HA-18
HA-19
HA-2l
HA-25
HA-27"
HA-28
HA-29
HA-4
HA-7
HA-9
HA-20
HA-22
HA-22
HA-23
HA-30
" II
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-------------------
-
HYDROLOGY
BASIN DESCRIPTION
Black Bear Lake is located on Prince of Wales Island eight miles east of
Klawock and nine miles northwest of Hollis, Alaska (Plate 1). The lake
is approximately at elevation 1,650 feet, National Geodetic Vertical Datum
(mean sea level), and has a surface area of 0.30 square miles. The·
total drainage area for Black Bear Lake (including the lake) is 1.82 square
miles (Plate 2).
The drainage basin is about two miles long with the lake extending about
70 percent of this length. The basin is oriented in a northwesterly
direction. Ground slope is very steep and averages 60 percent. Approx-
imately 80 percent of the 5.5-mile basin divide length exceeds 2,500 feet
in elevation with peaks to 3,996 feet. The average distance from the
basin divide to the lake is about 2,200 feet. The mean basin elevation
of 2,410 feet makes Black Bear Lake one of the highest basins on Prince
of Wales Island.
The drainage basin is very rocky with only about ten percent of the
drainage forested. Most of the trees are located at the lower elevations
near the lake. The upper elevations consist of bare rock and light
brush. grasses, and moss. Several avalanche paths and talus slopes
from the high rocky peaks extend into Black Bear Lake.
Black Creek leaves Black Bear Lake and drops 1,400 feet by a series of
falls and rapids within 0.6 miles. The stream trends ir'l a northwesterly
direction to Black Lake (Plate 2), 1.7 miles downstream of Black Bear
Lake and about 1,600 feet lower in elevation. Black Lake is about
0.8 miles long and has a total drainage area of 7.39 square miles. The
stream leaving Black Lake flows in a northerly direction for three miles
to tidewater at Big Salt Lake (Plate 2). The total drainage area of Black
Creek at tidewater is 17.46 square miles. The basin below Black Rear
Lake is heavily forested.
31 :a HA-l
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SCALE: APPROX. 1-= 30 mil ••
LEGEND:
$ -STREAM GAGE STATIONS
( S •• Station Nam •• b.low )
.-WEATHER STATIONS
1. BIG CREEK
2. NECK CREEK
3. STANEY CREEK
4. KLAWOCK RIVER
5. NB J'ROCADERO CREEK
6. KARTA CREEK
. 7. MA YBESO CREEK
8. HARRIS RIVER
9. INDIAN CREEK
10. VIRGINIA CREEK
0
DIXON ENTRANCE
11. CABIN CREEK
12. OLD TOM CREEK
13. REYNOLDS CREEK
14. UPPER MAHONEY LAKE
15. MAHONEY CREEK
LOCATION MAP
-
PLATE I 1~t(1
HA-2
.-.~' ~~------------------------..."
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Bill
) ";
. INCREMENTAL
DRAINAGE AREAS
(A).OUTLET TO BLACK BEAR
LAKE D.A.::1.82 sq.mL
(" .
<~. (B).INLET TO BLACK LAKE
D.A.:4'~ 48 sq.mL
,~(C).OUTLET TO BLACK LAKE
D.A.::1.08 aq.mL
1bJ~~~~~~~11-I_fH--r-W.WHfl1Wff~S~~\-(D).MOUTH OF BLACK CREEK
D.A.:::1CUI'7 aq.mL
DRAINAGE AREA MAP
HA-3
PLATE 21~1
CLIMATE
The climate of the area is maritime in nature. The climate is humid and
is typified by mild temperatures and heavy precipitation. Small diurnal
temperature fluctuations and relatively small mean temperature changes
from season to season are characteristic of· the region. The pacific air
is the moderating influence, but temperature extremes in both winter
and summer reflect occasional air mass invasions from Canada.
The climate in southeastern Alaska is closely related to the numerous
iow pressure systems created in the Aleutians. The storms move easterly
along the mainland cold front across the Gulf of Alaska to southeastern
Alaska. The low pressures create cyclonic wind patterns that rotate
counterclockwise (Coriolis effect). This produces prevailing southeasterly
winds in the Black Bear Lake region. The moist air cools and forms
precipitation as it rises over the colder continental air. The Black Bear
Lake area gets even more precipitation due to orographic effects. Sub-
stantial precipitation variations can be found throughout southeastern
Alaska and very little data has been collected.
Ketchikan is the nearest long-term climatological station to Black Bear
Lake. Ketchikan, near sea level, has a historical mean annual precipi-
tation of 156.06 inches and mean annual temperature of 45.7 degrees F
(Fahrenheit) • Table 1 shows the monthly variation of precipitation and
temperature at Ketchikan.
Table 1
Ketchikan Average Precipitation and Temperature
(63-Year Record)
January
February
March
April
May
June
July
August
September
October
November
December
Precipitation
Inches
14.33
12.49
12.08
11.80
8.98
6.47
7.94
11.24
13.50
22.47
18.50
16.26
Temperature
(Degrees F)
33.7
36.0
38.2
42.8
49.1
54.6
58.0
58.6
54.1
46.8
40.2
35.8
Other weather stations in the area are shown on Plate 1. Mean annua I
temperature at Hollis, nine miles southeast of Black Bear Lake, is 44.2
degrees F. January is the .coldest month at Hollis with an average tem-
perature of 32.4 degrees F, and August is the warmest month, with an
31: b HA-4
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average temperature of 58.1 degrees F. The temperature on the Black
Bear Lake drainage basin may average .approximately 8 degrees F cooler
than Hollis, due to the decrease in temperature with altitude. The aver-
age annual precipitation at Hollis is about 100 inches. Mean annual precip-
itation on the Black Bear Lake drainage basin is estimated to be near
220 inches. This large amount of precipitation is associated with orographic
effects.
31: b HA-5
STREAMFLOW
A streamflow gage was installed at the outlet of Black Bear Lake in June
1980 and is being serviced by the USGS. Due to the very short period
of record, the gage was of limited value in the hydrologic studies contained
in this report. The gage will become of greater value as more data is
collected. It is recommended that all analyses related to streamflow in
this report be reevaluated after at least one year of streamflow data
becomes available. This reevaluation is required prior to final design
of the project.
Streamflow Records
Since the streamflow gage at the outlet of Black Bear Lake has a very
short period of record, other gages in the area of Black Bear Lake were
utilized for the hydrologic analyses. These gages are listed in Table 2
and shown on Plate 1. Most of the stream gages in the area are near
sea level and record flows from basins with mean elevations considerably
less than that of Black Bear.
During the hydrologic analysis it was determined that the only other
basin in the area with characteristics similar to Black Bear Lake and
being gaged in 1980' was the Upper Mahoney basin. Although the Upper
Mahoney record is short, Lower Mahoney has been gaged for 25 years
and could be used to extend the Upper Mahoney record. It had been
. planned to compare the concurrent records of Black Bear Lake and Upper
Mahoney Lake and extend the short Black Bear Lake record if reasonable
to do so. Unfortunately, the required Upper Mahoney record was deter-
mined to be unusable by the USGS this fall.
Flow Synthesis for Black Bear Lake
To synthesize Black Bear Lake flows, other nearby gage records were
used. There are no stream gages in the immediate area. To use all of
the ava ilable flow data, the records of the area gages were reviewed.
The stream gage records, along with precipitation records, were used
collectively to estimate mean annual runoff, normal monthly distribution
of runoff, and variation of this normal distribution for a sequence of
years.
Mean annual runoff per square mile for each stream gage was plotted
versus mean basin elevation for gages near Black Bear Lake, on Prince
of Wales Island. An additional point was added to this plot for sea level
by converting the mean annual preCipitation at Hollis to a discharge.
This was done ,by assuming an 80 percent runoff coefficient. A straight
line was fitted through the points of nearby gages and gages on similar
basins and is shown on Plate 3. The orientation of the basins makes
little difference in the mean annual runoff. Orientation may be significant
for individual storm events. Therefore, the straight line was extrapolated
directly to the 2,41 O-foot mean basin elevation of the basin feeding Black
Bear Lake to obtain a mean annual runoff of 13.5 cubic feet per second
(cfs) per square mile. As a check on this value, the discharge per
square mile was estimated by two additional calculations.
31 :d HA-6
I
" I'
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I I I I I I I I I I I I I I I I I I I I I I I I I I I J I I I 1 I I I I I I
Table 2
Area Stream Gages
Drainage Mean Basin Elevation Runoff Per Square Mile Period of
No. on Gage Area Feet (Cubic Feet Per Second Record
Plate 1 Name (Square Miles) (Mean Sea Level) Per Square Mile) (Years)
1 Big Creek 11.2 360 7.84 15
2 Neck Creek 17.0 500 7.29 7
3 Staney Creek 51.6 600 6.94 14
4 Klawock River 46.1 1,150 6.49 1
5 N B Trocadero Creek 17.4 850 8.74 6
6 Karta Creek 49.5 1,000 9.27 7
7 Maybeso Creek 15.1 1,120 9.01 14
8 Harris River 28.7 1,400 8.92 15
9 Indian Creek 8.82 1,000 9.76 15
10 Virginia Creek 3.08 less than 200 5.58 2
S; 11 Cabin Creek 8.83 1,300 9.77 2
I 12 Old Tom Creek 5.90 1,000 6.47 29 '-I
13 Reynolds Creek 5.70 1,600 10.95 5
14 Upper Mahoney Lake 2.03 2,400 15.07 2
15 Mahoney Creek 5.70 1,680 18.24 25
31 :h:l
Runoff from the Black Bear Lake gage for August 1980 was compared
with concurrent precipitation at the Aiaska State Hatchery at Klawock,
near sea level seven miles west of Black Bear Lake. Runoff for this
period was assumed to have been almost entirely from precipitation.
Base flow at Black Bear Lake was separated from the recorded flow,
and it was determined that the stream gage recorded a runoff (converted
to inches over the basin) that was 1.83 times the precipitation recorded
at Klawock. The average annual precipitation at Klawock is not known,
but it should be very close to the mean annual precipitation at Craig of
105 inches per year. It was assumed that the above 1.83 factor observed
between Klawock precipitation and Black Bear Lake runoff during August
1980 is representative of conditions throughout the year. Therefore,
approximately 192 inches of runoff per year could be expected from
Black Bear Lake. This is equivalent to a mean annual runoff of 1 !I.l!1 cfs
per square mile.
A third estimate of the mean annual runoff for Black Bear Lake was
made by utilizing records from an old rain gage about 23 miles southeast
of Black Bear Lake. Precipitation was recorded at Jumbo Mine, elevation
1,500 feet, from 1915 through 1918. The mean annual precipitation at
Jumbo Mine was estimated to be 190 inches. Jumbo Mine records were
compared with the concurrent records at Ketchikan and adjusted to account
for the Ketchikan departure from normal during that period.
The average annual precipitation increase with increase in altitude was
assumed to be linear between sea level and Black Bear Lake. Since
Hollis is situated near Black Bear Lake and Jumbo Mine, it was used for
the sea level precipitation station. The average annual precipitation at
sea level (Hollis) is 100 inches, at 1,500 feet (Jumbo Mine) is 190 inches,
and at 2,410 feet (Black Bear Lake) is extrapolated to 240 inches. This
is equivalent to 15.9 cfs per square mile at Black Bear Lake with a runoff
coefficient of 0.9.
The three estimates of average annual runoff at Black Bear Lake (13.5,
14.1, and 15.9 cfs per square mile) were reviewed with all of the data
assembled for this analysis. Additionally, the short record at Upper
Mahoney Lake was analyzed, although the record is considered poor and
it is remote from Black Bear Lake. Since the precipitation record at
Jumbo Mine is very old and short, the runoff estimate using Jumbo Mine
data was considered least reliable. Therefore, it was assumed that the
. average annual precipitation at Black Bear Lake is between 215 and 220,
which is equivalent to 14.3 cfs per square mile. This produces a total
mean annual runoff of 26 cfs.
The monthly runoff variation for several of the nearby stream gages
was studied. A relationship of seasonal runoff versus mean basin eleva-
tion was developed for an area of Baranof fsland by the Alaska Power
Administration and the U. S. Bureau of Reclamation (Ref. 1). Runoff
variation for selected stream gages on Prince of Wales Island near Black
Bear Lake did not agree well with this relationship. This may be due
to lower precipitation on Prince of Wales Island.
31 :d HA-8
lit ..
I
I
• III
• iii
III
iii
" III
E.
----.. -
-
---.. .. ---.. -
-.. ---.. .. .. --..
----
Mean monthly runoff, as percentages of mean annual flow were estimated
from relationships between Maybeso Creek, Reynolds Creek, Lower Mahoney,
and Takatz Creek. The estimated normal monthly flows, as percentages
of mean annual flow, are shown in Table 3 for the Black Bear Lake drain-
age.
Month
January
February
March
April
May
June
July
August
September
October
November
December
Table 3.
Black Bear Lake
Monthly Runoff Percent
Normal % of
Mean Annual Flow
25
23
20
57
156
179
103
96
132
181
134
94
The variation of flows from year to year was accomplished by use of the
variation of precipitation from normal. A table of ratios of precipitation
at Ketchikan was developed. by dividing each monthly value of precipita-
tion by the normal precipitation for that month. A ten-year set of flows
for Lower Mahoney was developed by multiplying the precipitation ratios
by the Lower Mahoney normal monthly flow. These developed flows
correlated well with recorded Lower Mahoney flows for the same ten-year
period. Better correlation was obtained during the snowmelt months of
April, May, and June by shifting 50 percent of the portion of flows in
excess of the monthly average to the next month. Using these same
methods, 60 years of estimated flows for Black Bear Lake were developed •
The estimated low monthly flows appeared high and were adjusted to
more closely correspond to the calculated low flow probability •
The estimated monthly flows
were used as data in the Corps of Engineers computer program, H EC-4
(Ref. 2) to generate the 500 years of flows.
Flow Synthesis Downstream of Black Bear Lake
Flows were synthesized for three basins downstream of Black Bear Lake.
These basins are shown in Plate 2. The mean annual runoff for each
basin was determined by comparison of nearby gaged streams' runoff
versus elevation trends (see Plate 3). This is similar to the method
31 :d HA-9
-...
CD
CD --z
0 -l-
e(
> w
..J
W
~ Z -I en ~
0 e( m
w
<!J
e(
a: w > e(
2500
2000
1500
1000
500
o
4
BLA.~.J EA..B..b~~ ELEV. : 2 liCL ___ .--------7-$
$
. / ...
s
s
Ida Creek
.... .-
t.bln C,eek
"" ...
(I
.~ 5 0 5 (I
S Maybeao c,eek@ d -Indian Creek ... F Karta Creek (I
• NB Tro adero Creek S
Staney preek @~/ -... Nee k Creek
(! Big Creek <i)
S S
r-I. ~0.8 Klawo ~k Preclpltatlo n
~ a a 10 12 14 18
BASIN RUNOFF ( efa'aq.ml. )
BASIN ELEV A TION vs .. RUNOFF
S
(I S
S
,
LEGEND:
Nearby Gage Statio a on
Prine • of Walea I land
I Other (l age Statlone within
100 r ~lIe radlua
1a 20
PLATE 3 CH2M
II HILL
---------..
-----------..
---.. -----
-----
described for Black Bear Lake In the previous section. To determine
the average monthly variation in the calculated average annual runoff.
stream flow and precipitation were reviewed. Elevation effects on monthly
runoff were also evaluated. Maybeso Creek and Reynolds Creek flow
records and Ketchikan precipitation records were reviewed and plotted
to establish percentage of annual runoff for each month versus elevation
(see Plate 4).
Flows were synthesized for Maybeso Creek and compared with recorded
flows to establish empirical formulas for synthesizing flows on Black.
Creek basins. Correlations were lowest in the spring and summer. To
improve the correlation between predicted and recorded flows, adjustments
were made for temperature extremes and precipitation extremes.
The 30 years of synthesized monthly flow data for each basin downstream
of Black Bear Lake were then calculated To do this·
the mean basin elevation was used to determine average annual flow and
the average monthly percent of annual flow for each month. These monthly
values were then multiplied by 30 years of monthly precipitation record
from Ketchikan, as measured by deviations from the mean. Each of
these monthly flows was then adjusted using the empirical extreme temper-
ature and precipitation adjustments used on the test synthesis for Maybeso
Creek. Plate 5 shows the monthly average Black Bear basin flows and
corresponding Ketchikan precipitation and temperatures. Similar plots
for low, medium, and high years are shown in Plates 6-8.
31 :d HA-ll
z o -t-ee .> w
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---~ ----
--------------------
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--r--------____ r-____________ !.!:~~tK LAK ~ A~EA C
I
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=, ===, == I'~ ==:=== ===;=======i~Iil~:~~:~~; I
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500
/ ~I
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II i fA i 8
!!
.. OF MEAN
. MONTHLY PERCENT
OF ANNUAL RUNOFF
HA-12
200
CETCHIKAN PRECP .
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• iii
Q = RECORDED FLOW " III
:
PLATE 41~1 E
=
~~ --~----
---.. a.:
0-W,c -a:'E
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1vu
[E(;II"'. 1= 15
~MP. = 46.2
KEY
IInUII -&'1 Black
!moff a1 Upper
•• a1 ~lIun Lower
~noff a1 Mouth
).8/yr.
~F
Bear Ll
End Bl
End BI
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o~~~ , '////~~~~~ ~I~
OCT NOV DEC JAN FEB MAR APR MA~ JUN .u. AUG SEP
iVlONTHL y AVERAGE .V ALUES
HA-13 PLATE 5 I~ttl
~ eo ...
I-eo z
CII. 1° 40
0
Iii 30 ~
400
300
• -0
I
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0
100
~~~tt{~
~;~1~;,·.~ '~';'~~ ~:tl~· !~~~i~i
1948 14NN. ~ .. _-I~ -. -142.8·
11946 ANN. ITEMF • : 4E 1.7 of
~ K EY
~ A ~ ;:ut .... ~: at B lack 81 ~ar La. ~
B ~ :: ..... , ~ at ~ ~per E ~d ..... lL Lake ~ .
C ~ Rune Iff at L ~wer E ~nd _. _0. Lake
e : "':~ .. , ::: at .. ,.o.L Cl ~ alaI!' Creek
~ ~ I ~ \'\\ ~\\ D
\\ \ \
\\\~\\\\~\ ~ \~ ~~ \\ \\ ] \\' ~ ~ ~ W/hv//// /// ////..1 if/V// V//h Vffn ~ ~
OCT NOV DEC .IAN FEB MAR APR MAY .IUN .IUL AUG SEP
1946 -LOW FLOW YEAR . .
HA-14 PLATE 6~
.. ..
• II
•
III
II!I ..
II
iii
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• III
til ..
• ..
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" it
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II
-CI 9: CIS 0 .. -CD W > a: -< Q. 200 -~ Z .c -< -100 -c ~ 0
~ J:
0 --I-0 0 W
L<~tXiD rH/A:::~il I!}~;~ , : ::",-:; ':,::':-;;,:,
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0 30 .. I-
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~ --K~Y -400 1\ ;; t1un(; IT at ts laCK ts' ~ar LaK IS .. . B I: Rune Iff at U ?per E ~d Uae k Lake -C: ~ Runo "at Lc ~wer E ~d Blae ~ Lake --300
• --u
I -at > .. CIS
a 200 -.. -.. 100 -.. ..
~ D. ~ nUII\,j ii at M puth 01 Black Creek
~ ~ ~
~~ ~\~ ~ 1\ \\ '\ \
\\ 1\\' ~\I\\\ l\\ ~\' 1\ \ \ 0
j1 1\\'\ 1\ ~ ~ ~~/~ ~ ~ '//h~ ~ 419 V//h ..
OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP -..
-1944 -AVERAGE FLOW YEAR .. -.. PLATE 71~1 -HA-15 -
CD a as ...
CD > <
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100 • • 1949 AVG. PR
O •
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1949 AVG. TEM 70f 30 I
1M
• .. 400+----+----r----r----~--~--~~--~--~----~--_4----+_--~
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• OCT NOV DEC JAN FEB MAR APR MA Y JUN JUL AUG SEP
" •
• .. 1949 -HIGH FLOW YEAR
HA-16
..
PLATE 81~~1'
" ..
-..
---..
---.. -..
---..
-
-
---.. -
-
---..
----
FLOODS
Probable Maximum Flood (PM F)
The National Weather Service is currently preparing a Hydrometeorological
Report for Southeast Alaska. Advance copies of the probable maximum
precipitation (PMP) isohyetal map and a chart of depth-area-duration
relation for southeast Alaska PMP were used to develop the PMP for the
Black Bear Lake drainage basin. The 72-hour PMP for the Black Bear
basin produces 9.2 inches in six hours, 18.4 inches in 24 hours, and
31.3 inches in 72 hours. Precipitation was plotted in the form of a depth-
duration curve to aid in obtaining incremental rain •
The precipitation was arranged into a critical storm pattern as recommended
in the U. S. Weather Bureau's Hydrometeorological Report No. 43 (Ref. 3).
An SCS triangular unit hydrograph (Ref. 4) for a five-minute rainfall
duration was developed for the 1.52-square-mile land portion of the
basin. A curvilinear fit of the triangular unit hydrograph was used.
A time of concentration of 20 minutes was estimated using a combination
of overland flow and channel flow. The resultant five-minute unit hydro-
graph has a time to peak of 15 minutes and a peak flow of 2,943 cfs
and is shown on Plate 9 •
No infiltration losses were taken for the basin. The basin is almost
entirely solid rock, and was assumed to be completely saturated by ante-
cedent storms.
A base flow of 200 cfs was used for the entire 72-hour PMF. This flow
is consiCiered adequate to account for snowmelt conditions or to account
for runoff conditions from an antecedent storm. Either base flow condi-
tion is applicable since the PMP could occur during any season. However,
October is probably the most likely month for the PMP (Ref. 5).
The U.S. Army Corps of Engineers computer program, HEC-l (Ref. 6),
was used to combine the PMP with the unit hydrograph to obtain the
inflow PMF to Black Bear Lake. The inflow to the lake was combined
with the flow from direct precipitation on the surface of the lake to
obtain the PMF for Black Bear Lake. The flood has a peak flow of
4,000 cfs and a volume of 4,250 acre-feet and can be seen on Plate 10.
100-Year Floods
The 100-year floods were estimated for the outlet of Black Bear Lake,
the inlet to Black Lake, the outlet from Black Lake, and the inlet to
Big Salt Lake (see Plate 2).
The 100-year precipitation was estimated from the U. S. Weather Bureau's
TP 47 (Ref. 5). The storm produces 4.4 inches in six hours and 8.0 inches
in 24 hours. The precipitation was plotted as a depth duration curve
to aid in estimating five-minute precipitation increments. The storm
31 :e HA-17
aooo
2500
2000
-en
LL
0 1500 -
W
~ Cl a:
I < .... J:
00 0 en 1000 0
500
o
-PEA K : 2943 c s
EFF :CTIVE DUF ATION: 5r lin.
\
V
I ,
"' ~ r---.....
7.5 15 22.5 30 37.5
TIME (min.)
BLACK BEAR LAKE
UNIT HYDROGRAPH.
45 52.5 eo
PLATE 9 ~~I~
I J • I • J I I • J I I I I I I I I • I I I I I I I I I I I I I I I I • I I
~
t-'
""
.8 84
0
z-
0 ... 1 j::: ::J
0 <.&: ........ _ II)
Q. CD 2 -.&:
0 ()
w.5
0:_
Q. 3
PMF 7
K FLOW : 4000 cfs
UME: 50 ac et
-U 30
CD
II) ..... ... -:l
() -~ 2000
0
-I
LL
1000~------~-----+------~------~~----~~--~-------r------;-----~
0~0-------8~-----+,e------~------+-------~=----448-------5re------~e4~----~72
. TIME ( hours )
BLACK BEAR LAKE PLATE 10
PROBABLE MAXIMUM PRECIPITATION AND INFLOW HYDROGRAPH CH2M
::Hlll
was arranged as suggested by the U. S. B. R. Design of Small Dams ( Ref. 4).
The unit hydrograph used for the Black Bear Lake basin 100-year flood
was the same as that developed for the PMF. Rainfall losses were assumed
to be 0.05 inch per hour and base flow into the lake was assumed to be
30 cfs (approximately the estimated mean annual flow). H EC-l was used
to combine the 100-year precipitation with the unit hydrograph. This
flow into Black Bear Lake was combined with the flow from direct precipi-
tation on the lake to obtain the 100-year flood. The 100-year flood
peak flow was estimated to be 1,000 cfs (see Plate 11). I n order to
route the Black Bear Lake inflow, survey information was used to deter-
mine an approximate outflow rating curve. The channel cross-section at
the critical section in the outlet stream was found to be approximately
trapezoidal with a bottom width of 15 feet and side slopes of 1 V on 3.5 H
and 1V on 4.5 H. The outflow rating was developed by using the weir
head discharge relationship with a discharge coefficient of 2.6. This
relationship agreed well with the three stage-discharge points determined
by the U.S.G.S. The storage of Black Bear Lake above the outflow
elevation was estimated by using a constant lake area of 192 acres for
this routing. The outflow rating used for the lake is shown in Table 4.
Active
Storage
( Acre-Feet)
81
125
190
265
324
Table 4.
Black Bear Lake Outflow Rating
(Natural Channel Outlet)
Active
Discharge Storage
(cfs) (Acre-Feet)
10 407
20 478
40 689
70 918
100 1,094
Discharge
(cfs)
150
200
400
700
1,000
The routing of the 100-year flood resulted in a peak outflow from Black
Bear Lake of 400 cfs.
Unit hydrographs were developed for three subbasins downstream of
Black Bear Lake for use in determining the 100-year flood at the various
locations. The first subbasin was the area between Black Bear Lake
and the upper end of Black Lake. The second subbasin was the area
feeding directly to Black Lake with the lake area considered separately.
The third and last subbasin was the area between Black Lake and Big
Salt Lake. An infiltration rate of 0.05 inch per hour was assumed and
base flow for each area was the estimated mean annual flow for the sub-
basin elevation and area. The outflow from Black Bear Lake was lagged
30 minutes to account for the travel to Black Lake, and the outflow
from Black Lake was lagged 1 hour and 20 minutes for the travel to Big
Salt Lake.
31:e HA-20
• •
•• .. ..
• ..
I
I
I
I
" ..
" .. , ..
" ..
I I I I I I I J I I I I I I • I I I I J I I I I I I I· 1 • I I I I I I I I J
z-Q t-:;:,
I-0 c(.c 1-..... _ en
a. CD -s:. o CJ
W C a: .-
0.-
-.
$: (J
CD
I U)
N .....
I-' --. :;:,
CJ -3:
0
..J
IJ..
21 24
O
.2
.4
.8
.8
1
760
600
250
o +-----~~-----+------4-------~----_4------~------~------~----~ o 3 8 8 12 16 18 21 24
TIME (hour8 )
BLACK BEAR LAKE PLATE 11
100 YEAR PRECIPITATION AND INFLOW HYDROGRAPH CH2M I: HILL
In order to route the flow through Black Lake, aerial photos were used
to estimate a channel width at the outflow of Black Lake. The weir
head discharge relationship with a discharge coefficient of 2.6 was used
with a 30-foot-wide rectangular channel and a constant lake area of
83 acres to estimate the outflow rating shown in Table 5.
Active
Storage
( Acre-Feet)
44
70
98
155
286
Table 5.
Black Lake Outflow Rating
(Natural Channel Outlet)
Discharge
(cfs)
30
60
100
200
500
Active
Storage
( Acre-Feet)
455
596
722
946
1,330
Discharge
(cfs)
1,000
1,500
2,000
3,000
5,000
Table 6 shows the various parameters used for each subbasin, and the
100-year peak flow at each location.
As a check on the computed 100-year peak flows, Reference 7 was used
'to estimate 100-year flows based on aU. S. C .5. regional study. Both
sets of flows are tabulated below.
Table 7.
100-Yr. Flows
Cumulative
100-Yea r Pea k Flows
Computed U.S.C.S.
Flows Flows
Location (cfs) (cfs)
Black Bear Lake Inflow 1,030 970
Black Bear Lake Outflow 400 440
Upper End of Black Lake Inflow 1,740 2,540
Lower End of B lack La ke Inflow 3,320 3,170
Black Lake Outflow 2,670 2,430
Big Salt Lake Inflow 7,400 6,610
The agreement between the two methods is very good, especially when
considering the routing by the two lakes.
Flood Freguency Curves
Flood frequency curves were developed for Black Bear Lake and the
three downstream basins. These curves are used to estimate 10, 20,
31 :e HA-22
.. ..
• •
I III
..
IIIIiII
• ..
• III
III .,
" lit
• lilt
I I II • I I til.' I •• 1 I I •• II II I I II 11.1 II I I II
Table 6~
J
100-Year Frood Derivation
Incremental
Total Unit H~drogra~h
Drainage Area Time to Peak Peak Base Flow 100-Year Peak
(Miles) Hours) (cfs) (cfs) Flow
Black Bear Lake
Total Inflow 1.82 .25 2,943 30 1,030
Black Bear Lake
Routed Outflow 400
B lack La ke Inflow
at Upper End 6."30 .75 2,891 46 2,740*
$: Black Lake Inflow
I at Lower End 7.39 .33 1,394 8 3,320
N w
Black Bear Lake
Routed Outflow 2,670
Big Salt Lake
Inflow from Stream 17 .46 1.67 2,924 60 7,400*
*The 100-year peak flows at these subbasins include the flows from the above subbasln( s) •
31:h:2
50, and 100-year recurrence flood events. Since 100-year floods were
already calculated (see previous section), these values were included in
the curve development.
Peak flow data from nearby stream gages were plotted as frequency
curves using the Wei bull plotting position formula. From these curves,
peak 10, 20, 50, and 100-year recurrence flows were plotted versus the
basin drainage area for each gage.
An envelope curve was drawn for maximum flows for each frequency.
The envelope curves were found to be approximately parallel straight
lines. The 100-year flows computed for Black Bear Lake and the down-
stream areas were also plotted on the envelope curve for comparison
with the maximum 100-year peak flows of the area. These computed
flows formed a straight line which was parallel to the envelope curve
for the area. The 10, 20, and 50-year envelope curves for locations
along the drainage from Black Bear Lake were drawn parallel to the
100-year flow curve for the same drainage. Spacing was determined by
spacings between the various frequency envelope curves for the other
gages. Flow values for the 10, 20, 50, and 100-year recurrence inter-
vals were obtained from the curves and were plotted in the form of flood
frequency curves for each of the desired locations along the drainage
from Black Bear Lake. The flood frequency curves for Black Bear Lake
outlet, Black Lake inlet, Black Lake outlet, and Big Salt Lake inlet are
shown on Plate 12.
..
.. ..
• -
•
•• .. ..
• ..
" ..
A s a check on these flood frequency curves, the U. S. G • S. flood frequency ..
method (Ref. 7) was used to compute ten-year peak flow for Black Bear
Lake. This flow was within seven percent of the value shown on Plate 12. ""
These curves are based on undeveloped conditions. Regulation of flow
at Black Bear Lake or at downstream locations could significantly alter
flood pea ks.
Reservoir Routing for Spillway Design
The probable maximum flood (see Plate 10) was selected for the spillway
design flood. This design is to insure full hydraulic spillway protection
of the dam to prevent overtopping of the dam. The design of the spill-
way to pass the PMF is determined by the shape, width and elevation of
the spillway crest. The following assumptions were made prior to deter-
mining the required spillway width: .
31 :e
o
o
o
Ogee Crest Shape
Discharge coefficient, C, of 3.95
Q = CLH 3/2 , where
Q = discharge, cfs
C = discharge coefficient
L = length of spillway crest, ft.
H = total head on spillway, ft.
HA-24
.. .. ..
II!
..
• ..
I I I I I I I I I I til I • i I I I I I I I J I I I I • I
468043
I I I I I I I I
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nOt::. KEUFFEL a ESSER co. "AO( lit US" t
o 't,~~:·'~!'I·119~9~~IF';~~.~~.I.:~~I .. I;~:~.~I:~9~8!-:;1~~ .. ~~~~~~:!:~~f-!:~90j .. ~H~.~·~·~~~~:~-.~.~7~0~.~~~60~.;1~50mt~~~.1~30~·1f~~~2~011!'~O~:!-g.-.~~~5:~~lx::.-i:~~~~2~·:~f~~~~~lil~~'~I:':I.;I:I.2!<1=0~.liO~.0~5i.-:.cI~I·_O!
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7
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--.j-: 3
. 1--... --
-~.
~-I--
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· 1--
· . ~-I-----+-~-I+I~_Ij_~~++I+-l-t+++H-~~-+~~~4-~·~4~~~+I·~H4+H"~.f+f.~ IOub~-LLU~~-L-L~~ULLU~~-L~LLLU~~~~LLUW~~LULU~~~WW~~~~UW~~Li~~ULUU~~~~~~~~-L~ om 0.05 0.1 0.2 0.5 5 10 20 30 40 50 60 70 80 90 95 98 99 99.8 99.9 99.99
o
o
A maximum water depth of six feet is allowed over the
spillway.
The spillway crest elevation is 1,715 feet.
The 72-hour PMF and 200 cfs base flow were routed through the reser-
voir for spillway widths ranging from 30 to 50 feet. The 200 cfs base
flow produces a depth of water over the spillway and was used as the
condition at the beginning of the routing. This depth varies from about
1.4 to 1.0 feet, depending on the spillway width used.
The 72-hour PMF has a volume of 4,250 acre-feet and the unimpounded
lake has a surface area of 192 acres. The storage volume is a function
of the elevation of the water surface and was computed by assuming 1: 1
side slopes on the banks of the lake. The routing was accomplished by
using the U. S. A rmy Corps of Engineers computer program, H EC-l
(Ref. 6). The output of this mathematical model
was used to make Plate 13. This plate shows the peak outflow and the
peak depth of water above the spillway crest for varying spillway
widths. The 30-foot ogee crest spillway will pass the 72-hour PMF at a
peak flow of about 1,700 cfs and maintain a peak outflow depth of less
than six feet.
Plate 14 shows the inflow and routed outflow PMF hydrographs for a
30-foot wide spillway. The peak outflow is 2,000 cfs less than the peak
inflow and occurs about o'ne and one-half hours later.
Low Flow Frequency
The 7, 14, and 30-day low flows for Black Bear Lake were based on the
low flow frequency of nearby gaging stations. The developed low flow
frequency curves were divided by drainage area. The slopes of the
corresponding 7, 14, and 30-day lines were fairly constant. The differ-
ence of flow divided by drainage area between the duration lines for a
given recurrence interval was also quite steady. There was not a
strong correlation between the magnitude of the low flow and the mean
basin elevation. However, low flows at the higher elevations tended to
be slightly greater than those at lower elevations. Unfortunately, none
of the nearby gaged basins approach the elevation of the Black Bear
Lake basin. Since the basin is mostly rock, there is less opportunity
to sustain greater low flows since there is little ground water to be
released. Additionally, the very high elevation of the basin may cause
almost complete freezing of movable water in the winter. Therefore,
the low flow frequency curves for Black Bear Lake take the form of the
lowest curves from the nearby gages. For computation purposes, a low
flow of O. 1 cfsl mi was assumed to be the 7-day, 25-year low flow of
the area. The curves were drawn based on the slopes of the curves
from the nearby stations. The low flow frequency curves of 7, 14, and
30-day duration for Black Bear Lake are shown on Plate 15.
31:e HA-26
• •
..
• ..
• •
• ..
..
., -
..
•
lit
'" ..
-..
---.. -.. -.. -..
-.. -.--w w u.. .. --~ -
0 -..J u.. -u..
·0 .. J: .--a.. w .. 0
:E -::l .. ~
X
4( -:E ----------..
--
8.0 +---------------~--------------~---------------+
-PEAK OUTFLO --
1880 ct •
5.5 4---------------~----~~------~--------------~ K OUTFLOW =
1783 cia
PEAK OUTFLOW =
1799 cta
5.0 +-------------~------------_4~~--------__+
W=
K OUTFLOW =
1895 ct.
PEAK 0 FLOW =
1958 cta ---
4.5~------------~~------------~-------------4
30· 40 50
SPILLW A Y WIDTH (FEET)
SPILLWAY DESIGN CURVE
HA-27 PLATE 13
G-I2M
IIHIU
6000
4000
3000
-• ()
\1)
14 2000 ..... .... -• :I g: ()
I -N
00 ;:
0
..J
1000
U.
o
:----'INFLOW
PEAl k FLOW = 4000 cfs
PMF VOLUME ~ 4250 ac re -feet
~) {r"., ROUTEI 'w FOR ~ OUTFlO
30 FT. WIDE SPIL ~WAY
\ ,~ PEAK F lOW = 1. 80 cfs
~ ..,.""," ~ .......... I
~ .......... ......... ..... -------if __ -1----------"" ___
~--
o 8 18 24 32 40 48 158 84
TIME ( hours)
BLACK BEAR. LAKE PLATE 14
PROBABLE MAXIMUM FLOOD
INFLOW & OUTFLOW HYDROGRAPHS CHlM
II Hill
72
I I
10
9
8
7
6
5_
4
3
- 2 __
E
II
99.99
F':
-, --.-
-":;':: .:
---~---
-"-
• I I I I
99.999.8 99
".Mora .ABI~ ·1 Z L~ILES • IIIf\ ~tu.lHF'EL a'\::,::;i co. -mD[ IN U 5" ,.
98 95 90 80 70
1=++ -I+~ 1=_-_ -:: -:-t ... -111 -III
'! c:_ ~ _::_~.
:C'E -_-
Ft=:'~'
--
Il
1-
-t------~ -:"., ---,..
--. .I~ :! __ ._~_.
b¥ -~ -C:=.---=-~;:c ---
:'"!' 2~c1:g_
-8_~ _],C In -
~=
I I I I I I I
60 50 40 30 20
-1-
I .. J80~ I
10 5 2
-_ --~:=:= f----
:-I=r:-::=
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_ --= -~ -t== -
:: --:p--::---t -:=:--:
11-
r-= _AI--I-_
I I
1
.: I I I I
0.5 0.2 0.1 0.05 0.01
_'=c----
: -:: --r= .-
_ -_ r:-__
r--
-f-
---1-
-1--
--1----H-I--I-I+H++---+H-I"~--+-IO::~ ~:I--I+H-t~H+++-t--t-+-~ I-H-I H-t-t--l
--I---f--
I
c-
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........
00 ~U
--1---r ---p--j~----l+H--H++++++-I--
. -It-f-------
-.. - -I---t--t-II---p: ~ -1--1--N _
'9-~--~'3i·~1-·!=!llllliiilll!lIlIl!lilliillillllllllil!lIlIl!lilll!l!!iilllllllllll-!-~l!c~II:-illI!lIIII~-!-!!lIi'!--I--~;~~Ii'-9
1.0
c:(
.8 C -r-I j I==-~ ---c---=--:--~r~ --::~~'r:s:~---8
7 O . ---Ii' ~.-= -:+-----r----1----.-t:'; ~ - -----I ----.7 -I~ --~ ~ ------t-----o .6-f:j: j II =-.: ---I--I--t---- -~ : -. --1· -_te.:-:-------:::::. ~ 6
.4
.3
.2
.1
:i:'! ii::--'--~F' -_ -:_E ---1'1
c: _ _ .:..:.: "_-.-'.: - 5 ,--LLL==F=: : __ -: --_
-_____ :I-:::~: I:::_~-,:-: -----_==":::: :c-_ - -'-_ ______ _ _____ 4
~-i-··=-t!~i--~Jtt=-t-~--I--=il-=F-tt~~-~-~-~-=~--I-=~-i:=·-=-tt--·-=t~it.~~~rtHHit~J.I.'~-+H~+~~~H~-J;~H+H+i+rr+-l--~----+I----l+rHH~~-"I-~~--+-f-~~+-+-+-t=_-~.-1
II
I -1::: -------1= ~. :-----W ,---:: --::--::.: : ----: :: -:1= ------: 1--= : --· It -::: ~I-===t= _: _ _ ~ __ r~: _~-. _ _ __ _ - - --: I; ~~:.: : ~~. ~-: __
.. /-
r--t-----l-l--+l-H-+++-H+I+H-++I-+++H+
-r---
0.01 0.05 0.1 0.2 0.5 2 5 10 20 30 40 50 60
1--
----1-
70 80 90 95 98 99 99.899.9
----f--
I -
CH;M ~rH!tt
-,--1-
99.99
3
10
9
8
7
6
5
4
3
2
I I
EVAPORATION
Evaporation from a free-water surface is controlled by a number of inter-
dependence factors: temperature of the water and air, wind, atmospheric
pressure, quality of the water, and the nature and shape of the water
surface. Because of such interdependence, a high correlation between
evaporation and anyone of the controlling parameters cannot be expected
(Ref. 8).
Due to the dominating maritime influence, the climate of the Black Bear
Lake basin is mild and humid with much precipitation. Prevailing winds
bring rain and, therefore, have I ittle or no capacity to remove water
vapor produced by evaporation. The predominance of overcast days
and relatively cool temperatures also precludes any appreciable evapora-
tion losses. Evaporation virtually ceases in mid-winter when Black Bear
Lake freezes over.
The nearest Weather Bureau station for which evaporation data are avail-
able is located at the Juneau airport. As shown below, average monthly
evaporation losses totalling 15.91 inches were observed at Juneau between
1968 and 1977 (Ref. 9).
~
3.30
Table 8.
Average Monthly Evaporation Losses, Juneau Airport
( Inches)
June
3.76
~
3.98
August
3.47
September
1.40
Total
15.91
These are pan evaporation values and are not representative of evapor-
ation from a large free-water surface such as a lake or reservoir. An
assumed annual Class A pan coefficient of 0.70 (Ref. 10) gives an
estimated equivalent annual lake evaporation of 11.14 inches.
The annual evaporation loss at Black Bear Lake is probably less than at
Juneau because of a higher annual precipitation and lower average annual
temperatures. Therefore, it is estimated that the mean annual evaporation
losses in the project area range from six to eleven inches.
31 :f HA-30
I
I
I
I
I
I
I
I
I
" ..
I
-
-.. -.. -
-..
-.. -.. -... -
--
-• -
-..
-
-
-...
SEDIMENTATION
The Black Bear Lake basin is in steep rock and talus slopes and has
very little soil cover. Vegetation is sparse and covers only about
50 percent of the basin, primarily at the lower elevations. Trees cover
only about 10 percent of the basin. There are several small snowmelt
streams in the basin.
Available sediment data for Alaska streams do not include measurements
for small basins such as Black Bear Lake. However, these sediment
observations indicate that suspended sediment is not a significant problem
in basins not containing active glaciers. Published reports (Ref. 1, 11)
indicate sediment yields of Alaska streams ranging from 0.1 to 5.1 acre-feet
per square mile per year. The higher value is for a drainage area with
a glacier cover of 22 percent •
Because there are no glaciers in the Black Bear Lake basin, the suspended
sediment production rate is expected to be at the low end of the reported
range. The sedimentation rate for the 1. 5-square-mile land portion of
the basin is estimated to be about 0.15 acre-foot per year.
Bedload portions of material entering Black Bear Lake would consist
mainly of rockslides and rockfall accompanying the normal weathering
process. There are a number of old rockslides around the lake: None
. appear to be very recent, and the talus slopes appear to be stable.
Vegetation has been re-established in the major rockslide areas. The
accumulation of rock is most likely to occur as the result of mechanical
weathering, particularly frost wedging in the bedrock formation. In
any given year it is possible for a significant quantity of sliderock to
be carried into the lake. However, since there is no evidence of this
having taken place recently, the average annual sediment contribution
due to slide hazard is relatively small. It is estimated that the sediment-
ation rate due to rockslides and avalanches is about 0.2 acre-foot per
square mile per year, for an annual total of 0.3 acre-foot for the
1.5-square-mile basin.
In the higher elevations of the study area, snow depths in excess of
20 feet may be reached. Snows of these magnitudes build up on the
steep slopes of the drainage basin until enough weight is accumulated to
overcome the shear friction in the snow and create an avalanche. The
exact critical angle of repose depends on the temperature, wetness, and
shape of the snow grains. There is evidence that avalanches occur
with regularity at a number of locations in the Black Bear Lake basin
and· are apt to occur at any susceptible location. It can be assumed
that all treeless slopes, gullies, and bowls steeper than about 30 0 are
possible avalanche paths (Ref. 12). An avalanche carries with it any
debris, such as rocks and vegetation, in its path. Debris drops out
continuously. The amount of sediment annually borne into Black Bear
Lake by avalanches is probably small. It is assumed to be included in
the amount estimated as the annual contribution due to· rockslides.
31 :g HA-31
--------------------------------------------------------
The total annual sediment production rate for the Black Bear Lake basin
is estimated to be 0.5 acre-foot. This results from a suspended sediment
deposition rate of 0.1 acre-foot per square mile per year and a bedload
or rockslide and avalanche contribution rate of 0.2 acre-foot per square
mile per year for the 1.5-square-mile-basin.
31 :9 HA-32
.. ... , .•.. III
III
iii
" iii
• •
-
.. --•
•
•
•
• .. -• -..
-
--
-..
II
.. .. ..
-.. ..
-
REFERENCES
1. U.S. Department of the Interior, Alaska Power Administration,
Takatz Creek Project, Alaska, Juneau, September 1967.
2. U.S. Army Corps of Engineers, Hydrologic Engineering Center,
H EC-4, Monthly Streamflow Simulation, February 1971.
3. U • S. Department of Commerce, Weather Bureau Hydrometeorological
Report No. 43, Probable Maximum Precipitation, Northwest States,
Washington, D.C., November 1966.
4. U.S. Department of the Interior, Bureau of Reclamation, Design of
Small Dams, Washington, D.C., 1977.
5. U.S. Department of Commerce, Weather Bureau, T.P. 47, Probable
Maximum Precipitation and Rainfall-frequency Data for Alaska,
Washington, D.C., 1963.
6. U.S. Army Corps of Engineers, Hydrologic Engineering Center,
HEC-l Flood Hydrograph Package, January 1973 •
7. U. S. Geological Survey, Water Resources Investigations, R. D.
Lamke, Open-file Report 178-129, Flood Characteristics of Alaskan
Streams, 1978.
8. Veihmeyer, F. J., IIEvapotranspiration ll in Handbook of Applied
Hydrology, V. T. Chow, ed., New York: McCraw-Rill, 1964.
9. U.S. Department of Commerce, National Climatic Center, Clima-
tological Data for Alaska, annual summaries 1968-1977.
10. linsley, R. K., Jr., M. A. Kohler, and J. L. H. Paulhus,
Hydrology for Engineers, 2nd Ed., New York: McGraw-Hili,
1975.
11. U. S. Army Corps of Engineers, Alaska District, Rivers and Harbors
in Alaska, Interim Feasibilitk Reiort on Hydroelectric Power and
Related Purposes for Ketchi an rea, Alaska, 1978 •
12. U. S. Department of Agriculture, Forest Service, Avalanche Handbook,
November 1978 •
31 :h HA-33
-
---
III
-..
-..
-----------..
-
• -
---
,,.
BLACK BEAR LAKE HYDROELECTRIC PROJECT
FERC NO. 5715
EXHIBIT I
ESTIMATE OF THE DEPENDABLE CAPACITY AND AVERAGE ANNUAL
ENERGY OUTPUT TO BE GENERATED BY THE PROJECT
ALASKA POWER AUTHORITY
ANCHORAGE, ALASKA
-----------
-----------
-
------------
BLACR BEAR LAKE HYDROELECTRIC PROJECT
EXHIBIT I
Table ot Contents
Dependable Capacity and Average Annual Energy
Flow Duration Curve
Tailwater Rating
Plant CaFacity
1-1 Power
1-2 Energy
1-3 Flo~ Duration Curve
1-4 Tailwater Rating Curve
1-5 Plant Capacity
I-i
Page
1-1
1-2
1-2
1-2
----------------------------------
---
BLACK BEAR LAKE HYDROELECTRIC PROJECT
EXHIBIT I
STATEMENT OF THE ESTIMATED DEPENDABLE CAPACITY
AND AVERAGE ANNUAL ENERGY
Dependable Capacity and Average Annual Energy
Power and energy studies were conducted using the hydrologic
data presented in Exhi~it H, and the projections of load
characteristics for tne Craig-Klawock-Hydaburg area which are
discussed in Exhibit W, Section 8.1. A computer program was used to
determine the monthly firm power and energy available. (A 95 percent
probability of exceedance was selected as the critical design
sequence for reservoir operation study because it gives an
acceptable level of firm power and energy when the system thermal
reserves are considered.
In order to reduce the potential environmental impacts, the
maximum flow releases were limited during the months identified as
important for salmon spawning (July through November) and incubation
(December through May). ~ detailed presentation of minimum and
maximum flow releases during these months is presented in Exhibit H
and W. Based on the forecast load demand in Year 1992 when the
Project will be fully utilized, Figure 1-1 shows the resulting
monthly firm capacity, and Figure 1-2 shows the average monthly
energy available from the Project.
Although tne Project has a capability of 6,000 kW in July, the
annual firw. capacity is only 4,000 kW because of the constraints on
maximum flow releases during the month of August. Based on a
95% exceedence level, the firm annual energy is 22,125,000 kWh. Tne
average annual energy is 23,100,000 kWh.
When the Project comes into service, the existing diesel 'mits
will be used as ready reserve or standby units and to meet the peak
load demand when environmental constraints limit the maximum daily
discnarge. It is likely that, it the project on line date is
delayed beyond 1986, a new diesel unit will be needed to meet
increasing capacity and energy requirements.
~here are no plans tor tuture hydro projects on the Black Bear
Creek. A potential hydropower development which is less attractive
economically at this time, would be the Lake Mellen Project, located
in the Reynolds Creek BaSin, east of the town of Hydaburg.
1-1
Flow Duration CUrve
~he flow duration curve for Black Bear Lake outflow is shown in
Figure I-3. This curve was developed using 30 years of synthesized
monthly inflows described in Appendix A of Exhibit H.
Tailwater Rating
The power plant will discharge into Black Bear Creek. The
tailwater rating curve is shown in Figure I-4. The center line ot
the Pelton units will be at Elevation 263 feet, which is 9 feet
above the tail water elevation under the probable maximum tlood
conditions.
Plant Capability
Figure I-5 shows the plant capability versus the reservoir
elevation. A capability ot 6,000 kW is available at Elevation 1685
which is the m1n1mum reservoir elevation. At maximum reservoir
elevation (1115), the plant has a capability of 6,195 kW.
• •
• •
I •
I
, •
II II II I. I. II II II II II I II II II II II I J II II
LEGEND:
I 4000
o
~++++~-~HhH++++++t++++++++++++++++++~++~~·~~~~H-~
DIESE ~ C~~~C1~~ HrH-++f-+-t+-t+++++t+++++H-~f--\-~l-+I-+-H-lH--iH--i--l-i-l-f+'
~h ~ 'Ii~ ~~~.H-+H-t+++-ll-t--t--H-H-t-t+-t-H-+++++++-H-+HY-I++-t-+-.-
I I I
! I, r r i " I I
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
YEAR 1992
PEAKING CAPABILITY AS LIMITED
BY MAXIMUM ALLOWABLE RELEASE
FIGURE 1-1
_. _. -LOAD DEMAND BLACK BEAR LAKE
HYDROELECTRIC PROJECT
ALASKA
POWER
J..-tARZA ENGINEERING CQI\M>ANY . MARC ... 198'
ALASKA POWER AUTHORITY
LEGEND:
-----
4000
3000
.z:
12000
> o a:
1&1 z
1&1
1000
o
FIGURE 1-2
. iiI" .
I I
JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
YEAR 1912
AVERAGE ENERGY AVAILABLE
ENERGY DEMAND BLACK BEAR LAKE
HYDROELECTRIC PROJECT
ALASKA
ENERGY
ALASKA POWER AUTHORITY
iii iii Ii il i. Ii •• II II I. II II II II II I. II I.
en u.
U
80
60
Z 40
:t o
...I
U.
20
o
~
\
"I11III
o
~ ~ ........ ~ -..... ..........
10 20
1---lA.R..z.A ENGINEERING CC'V1PANY • MARC"'" 1981
r---.. r---.. .....
--r---~
r---. -.......
30 40 50 60 70
PERCENT OF TIME EOUALED OR EXCEEDED
80
FIGURE 1-3
90 100
BLACK BEAR LAKE
HYDROELECTRIC PROJECT
ALASKA
FLOW DURATION CURVE
M.ASKA POWER A~
254
...I
W > W
...I
< 252 w en
Z < w
:IE ... : 250 w w u.
I
Z
0
i= 248 < > W
...I
W
a: w .... 246 < ~ < ....
244
~
~ ~
~ V ,
o 200 400
~z.A. ENG'''''~EERt'''G ::'OMPANY • MA~Ct-4 '981
~ ~
~ ......
~ ~
~
~ ~
600 800 1000 1200
BLACK BEAR CREEK FLOW -CFS
1400 1800
FIGURE 1-4
-•
2000 2200
BLACK BEAR LAKE
HYDROELECTRIC PROJECT
ALASKA
TAILWATER RATING CURVE
I I I • I I I I I I I I • I I I I I I I I I I I I I I I I I • I I I I I I I
1750
-
j::
u.
Z
0
~ > w 1700 ...I
W
a:
0
~
~ ~
-""" > a: MIN. W.S. 1685' ~ w en w a:
1650
5900
~z..A. ENG,r-...,EEQII'."tG COMPANY '\11.4 r::IC 1-4 • "981
6000 6100
PLANT CAPABILITY (kW)
MAX. W.:,:~
~ ",-
6200
FIGURE 1-5
BLACK BEAR LAKE
HYDROelECTRIC PROJECT
ALASKA
PLANT CAPACITY
ALASKA POWER AUTHORITY
---..
---..
-
---..
-
----
-..
-----..
-.. -.. ----
BLACK BEAR LAKE HYDROELECTRIC PROJECT
FERC NO. 5715
EXHIBIT J
GENERAL MAP COVERING
THE ENTIRE PROJECT AREA
ALASKA POWER AUTHORITY
ANCHORAGE, ALASKA
SCALE 0
KEY MAP
N
28.5'
NOTE: TOPOeliAPHY SHOWN IS A REPItOOuCnOll
MUseS IIIAPCRAI8,ALASIIA, 1'250,000
SCAL£. THE COIIITOUR IIIT£RVAL 18 200 FEET.
DATUIII IS IIIEAN SEA LEVEL.
UIPID
----IIOMII
--TIl". 11I0Il UNt:
EX"'T~ET.LM...!..
,... drowlng Ia. port of iii.
....... tIOIIforl __ ..... .., .................. '
n.. .. ..,.'~.I .. 1
AlASKA POWER AUTHORITY
•
.., h= a 't U ~"DlrMIor
.. • 8 10 ---------1:100,000
BLACK BEAR LAKE
HYDR.QELECTRIC PROJECT
ALASKA
GENERAL MAP
-U..ASKA POWER AUTHORITY
'DWG. NO. 5715-1
--
-
-------
-
-
-----------
-
--...
--
-
BLACK BEAR LAKE HYDROELECTRIC PROJECT
FERC NO. 5715
EXHIBIT K
DETAILED MAPS COVERING
THE ENTIRE PROJECT AREA
ALASKA POWER AUTHORITY
ANCHORAGE, ALASKA
-----
-
---
----------
---
-
-
.-
..
BLACK BEAR LAKE HYDROELECTRIC PROJECT
EXHIBIT K
PROJECT DETAIL MAP
Exhibit K drawings, Sheets I through 6 of 9, show the Proposed
Project Boundary for the area affected by the Project. The proposed
boundary includes sufficient area for all project structures and
other access, construction plant area, operation and maintenance
activities, and recreational facilities.
The Applicant has not shown the Proposed Project Boundary in
more detail at this time since negotiations for acquisition of the
required lands are dependent upon further development of the project
design. Upon completion of the investigations necessary to further
develop the project design, negotiations will be held with the land
owners for the necessary land and land rights to construct and
operate the Project. After agreement is reached with the land
owners, the Project Boundary will be surveyed and the Exhibit K
drawings revised to show the Project Boundary as surveyed and
procured.
Additional information, including the reservoir area-capacity
curve, a tentative centerline survey of the penstock, and tentative
locations of the project transmission line substations at Hydaburg,
Klawock and Craig, is shown on Exhibits K-7, K-8 and K-9
respectively.
K-I
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SCALE 0
KEY MAP
N MN
2B.~
NorESI
I. ESTIMATED TOTAL ACREAGE OF U.S. LANDS
WITH ... THE PROJECT BOUNDARY ON THIS
EXHIBIT IS 791.~ ACRES.
2. TOPOeRAPH,( SHOWN IS A REPfIODUC:TJDN
OfF uns IIAP CRAIII, ALASlCA, 1:250,000
SCALL THE COIfTOUR IlTERYAL 18 200 FEET.
DATUM IS MEAN SEA LEVEL.
LE8END
----ROADS
--TRAN8IIISSIDN LINE
EXH8IT_K_SHEET...LOfF ...!.
T1III _ ..... part" ....
appIIoa .... farl'-_
"' .... ..., ..... d~
Tllla4ll..,of -r-...IMI
ALASKA POWER AUTHORITY
'" 5.,. a ~.J.l ~ .. _
• • 10 ---- -----
BUCK BEAR LAKE
HYOROEL£CTRIC PROJECT
ALASKA
DETAIL MAP
ALASKA POWER AUTHORITY
DWG. NO. 5715-2
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PROJECT BOUNDARY SURVEY DATA
ALASKA STATE PLANE
POINT COORDINATES
DAMSITE N E
01 49.180 100.000
02 49.300 99.600
03 50.000 99.310
04 50.000 99.550
05 50.000 100.000
06 49.890 100.110
POWERHOUSE N E SITE
PI 51.725 99.460
P2 51.860 98.260
P3 51.860 97.860
P4 52.170 97.620
P5 52.280 98.820
P6 52.280 98.120
P7 52.120 98.220
P8 52.840 98.680
LEGEND:
PROPERTY LINE
-----PROPOSED TRANSMISSION LINE
APPROXIMATE PROJECT BOUNDARY
PROPOSED WILDERNESS AREA
BOUNDARY
NOTES:
ESTIMATED ACERAGE OF SECTION
INCLUDED IN PROJECT BOUNDARY
I. TRANSMISSION LINE LOCATION SHOWN
IS APPROXIMATE. PROPOSED PROJECT
BOUNDARY LINES ARE OFFSET 100 FEET
FROM THE TRANSMISSION LINE ON BOTH
SIDES.
2. TOPOGRAPHY SHOWN IS A REPRODUCTION
Or' USGS QUADRANGLE SHEET C-3
CRAIG. ALASKA. THE CONTOUR INTERVAL
IS 100 FEET. DATUM IS MEAN SEA LEVEL.
3. PROPERTY LINES SHOWN ARE BASED ON U.S ..
DEPARTMENT OF AGRICULTURE FOREST
SERVICE-ALASKA REGION PUBLICATION NO.
103. "PRINCE OF WALES ISLAND ROAD SYSTEM.
TONGASS NATIONAL FOREST".
4. TOTAL ESTIMATED ACREAGE OF U.S. LANDS
INCLUDED WITHIN THE PROJECT
BOUNDARY ON THIS EXHIBIT -329.8 ACRES.
EXHIBIT_K_SHEET LOF..!
Thll drawin~ II a part 01 the
application for IIcen .. modi
by the und ... I~n.d.
Thll~daJof~. 19BI
ALASKA POWER AUTHORITY
. b, \....:-\? ~.ll Executiy. Oirector
,SCALE
400 800 1200 1600 2000 2400
!ijjo.--
1"-400 FEET
BLACK BEAR LAKE
HYDROELECTRIC PROJECT
ALASKA
DETAIL MAP
ALASKA POWER AUTHORITY
DWG. NO. 5715-3
r
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[ COURSE NO. BEARING DISTANCE
1-1 N 68° 10' W 4300
1-2 N 57° 20' W 2700
1-3 N 20° 25' W 2550
1-4 N 7° IS' W 4200
1-5 N 15° 45' W 4000
1-6 N 7° 10' W 5700
1-7 N 59° 0' W 800
1-8 S 70° 0' W 1150
1-9 N 20° 40' W 1800
1-10 N 57° 40' II 2900
1-11 S 76° 30' W 1300
1-12 S 62° 20' W 2100
1-13 N 49° 55' W 1250
1-14 S 70° 50' W 2400
1-15 S 37° 15' W 1750
1-16 S 8° 25' W 11 00
1-17 S 21 ° 55' W 2350
1-18 S 50° 30' W 1100
1-19 S 35° 40' W 2100
1-20 S 90° 0' W 1200
1-21 S 39° 5' W 2050
1-22 S 80° 10' W 1650
1-23 S 60° 40' W 950
1-24 S 29° 5 ' W 2650
1-25 S 47° 30' W 7250
1-26 S 20° 50' W 3800
1-27 S 39° 50' W 5300
1-28 S 9° 10' E 1600
2-1 S 9° 30' E 11 00
2-2 S 4° 55' W 3400
2-3 S 61 ° 10' W 2300
2-4 S27°40'W 2300
2-5 S 48° 30' W 2350
2-6 S 28° 50' W 3450
2-7 S 20° 0' W 1850
2-8 S 0° 0' W 1400
2-9 S 5° 55' W 2450
2-10 S 59° 0' W 800
2-11 S 6° 25' II 4000
2-12 S 50° 5' E 2400 L
2-13 S 9° 30' W 1700
2-14 S 38° 15' W 1900
2-15 S 63° 25' W 350
TRANSMISSION LINE CENTERLItlE SURVEY
REFERENCE COURSE NO.
Exhibit K 4 3-1
00 K 4 3-2
K 4 3-3
K 4 3-4
Exhibit K 3 3-5
K 3 3-6
K 3 3-7
K 3 3-8
K 3 3-9
K 3 3-10
K 3 3-11
K 3 3-12
K 3 3-13
K 3 3-14
K 3 3-15
K 3 3-16
K 3 3-17
K 3 3-18
K 3 3-19
K 3 3-20
K 3 3-21
K 3 3-22
K 3 3-23
K 3 3-24
Exhlbit K 4 3-25
K 4 3-26
K 4 3-27
K 4 3-28
3-29
Exhibit K 4 3-30
K 4 3-31
K 4 3-32
K 4 3-33
K 4 3-34
K 4 3-35
K 4 3-36
K 4 3-37
K 4 3-38
K 4 3-39
K 4 3-40
K 4 3-41
K 4 3-42
K 4 3-43
K 4
BEARING
S 87° 25'
S 50° 55'
N 68° 20'
S 60° 0'
S 65° 10'
S 56° 55'
S 33° 10'
S 55° 50'
S 48° 55'
S 40° 10'
S 32° 30'
S 51° 45'
S 81° 10'
S 63° 45'
S 3° 25'
S 54° 5'
S 45° 30'
S 23° 35'
S 3° 0'
S 33° 10'
S 40° 35'
S 45° 50'
S 22° 20'
S 9° 5'
S 25° 5'
S 0° 0'
S 60° 0'
S 4° 35'
S 39° 25'
S 8° 40'
S 29° 45'
S 90° 0'
S 26° 0'
S 23° 5'
S 0° 0'
S 4° 55'
S 6° 35'
S 33° 25'
S 8° 40'
S 14° 30'
S 29° 5'
S 6° 5'
S 30° 10'
E
E
E
E
E
E
E
E
E
E
E
E
E
E
W
E
E
E
E
W
E
W
E
W
W
W
W
W
W
E
E
E
E
W
W
W
W
E
E
W
W
W
W
DISTANCE
3300
2200
4300
2100
3150
3750
4750
4900
4100
2100
4600
8800
6200
3750
5050
3250
1500
2750
2300
4450
8850
4700
5000
7550
4750
7350
1450
1500
7450
6950
4850
7950
2350
3650
2650
3750
3900
3050
4650
1600
2400
1900
1800
LINE
N
MATCH LINE
SHEET NO. K4
REFERENCE
Exhibit K 4
K 4
K 4
K 4
K 4
K 4
K 4
K 4
K 4
K 4
Exhibit K 5
K 5
K 5
K 5
K 5
K 5
K 5
K 5
K 5
K 5
K 5
K 5
K 5
K 5
K 5
K 5
K 5
K 5
K 5
K 5
Exhibit K 6
K 6
K 6
K 6
K 6
K 6
K 6
K 6
K 6
K 6
K 6
K 6
K 6
MN
LEGEND: .
1-23
NOTES:
RANSMISSION LINE
FOREST DEVELOPMENT ROAD
AND NUMBER
PROPOSED TRANSMISSION LINE
AND COURSE NUMBER
PROPERTY LINE
ESTIMATED ACREAGE OF SECTION
INCLUDED IN PROJECT BOUNDARY
I. TRANSMISSION LINE LOCATION SHOWN
IS APPROXIMATE. PROPOSED PROJECT
BOUNDARY LINES ARE OFFSET 100 FEET
FROM THE TRANSMISSION LINE ON BOTH
SIDES.
2. TOPOGRAPHY SHOWN IS A REPRODUCTION
OF USGS QUADRANGLE SHEETS C-3 AND C-4,
CRAIG. ALASKA. THE CONTOUR INTERVAL
IS 100 FEET. DATUMIS'MEAN SEA LEVEL.
3. PROPERTY LINES SHOWN ARE BASED ON U.S ..
DEPARTMENT OF AGRICULTURE FOREST
SERVICE-ALASKA REGION PUBLICATION NO.
103. "PRINCE OF WALES ISLAND ROAD SYSTEM.
TONGASS NATIONAL FOREST".
4. ESTIMATED TOTAL ACREAGE OF U.S. LANDS
WITHIN THE PROJECT BOUNDARY ON THIS
EXHIBIT IS 25.9 ACRES.
MATCH LINE
SHEET NO. K4
EXHIIIIT ....ILSHEET lOf..!.
T1III dNwt", loa part"' ... ....... ' ... ,.,1 ... _ .... .., ................. .
TN. .. .., of ~ It81
ALASKA POWER AUTlIORITY
.., ~ oCr B u..J.l ~I •• DIrecIar
SCALE 0 2000 4000 aooo 8000 10000 12000". ..,...--
1".2000 FEET
BLACK BEAR LAKE
HYDROELECTRIC PROJECT
ALASKA
DETAIL MAP
ALASKA POWER AUTHORITY
DWG. NO. 5715-4
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LEGEND:
--@-8TATE IIGHWAY AI«) NUMBER
~ ~~LOPIoIENTROAD
3-23 ~ot\~n:.t':.':::SlON LINE
--- -PROPERTY LINE
N
ESTIIiATED ACREAGE OF SECTION
INCLUDED IN PRO~ECT BOUNDARY 29·
NOTESI
I. TRAN8MI8SION LINE LOCATION SHOWN IS APPROXIMATE.
PROPOSED PROJECT BOUNDARY LINES ARE OFFSET 100'FEET
FROM THE TRANSMISSION LINE ON BOTH SIDES.
2. TOPOGRAPHY SHOWN IS A REPRODUCTION OF USGS
QUADRANGLE SHEETS B-4. C-S. C-4. CRAIG. ALASKA. THE
CONTOUR INTERVAL IS 100 FEET. DATUM IS MEAN SEA LEVEL.
S. PROPERTY LINES SHOWN ARE BASED ON U.S •• DEPARTMENT
OF AGRICIA. TURE FOREST SERVICE-ALASKA REGION
PUBLICATION NO. lOS. "PRINCE OF WALES ISLAND
ROAD SYSTEM. TONGAS8 NATIONAL FOREST" •
4. PftOPOSED TRANSMISSION LINE CONNECTION TO KLAWOCK
AND CRAIG DISTRIBUTION SYSTEIIS ARE SHOWN ON FIGURE K-3.
S. UTIIiATED TOTAL ACREAGE OF U.S. LANDS WITHIN THE
PROJECT BOUNDARY ON THIS EXHIBIT IS 351.0 ACRES.
INCLUDING 329.8 AlCRES FROII SHEET NO. K2.
liN
EXIIBIT_"_SHEET ..!..OF..L
TIIIa ........... part of 1M .............. ,,--...
IIftlle ....... I ... d.
~..,of~ .. 81
AUSlCA POWER AUTHORITY
)
., ... A 't U. b_I •• DIt ...
SCALE 0 2000 4000 eooo BOOO 10000 12000 "" -1··2000 FEET
BLACK BEAR LAKE
HYDROEL£CTRIC PROJECT
ALASKA
DETAIL MAP
ALASKA POWER AUTHORITY
DWG. NO. 5715-5
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LEGEND:
---@-STATE HIGHWAY AND NUMBER
~
3-23
NOTES:
FOREST DEVELOPMENT ROAD
AND NUMBER
PROPOSED TRANSMISSION LINE
AND COURSE NUMBER
PROPERTY LINE
ESTIMATED ACREAGE OF SECTION
INCLUDED IN PROJECT BOUNDARY
I. TRANSMISSION LINE LOCATION SHOWN
IS APPROXIMATE. PROPOSED PROJECT
BOUNDARY LINES ARE OFFSET 100'FEET
FROM THE TRANSMISSION LINE ON BOTH
SIDES.
2. TOPOGRAPHY SHOWN IS A REPRODUCTION
OF USGS QUADRANGLE SHEET B-3
CRAIG. ALASKA. THE CONTOUR INTERVAL
IS 100 FEET. DATUM IS MEAN SEA LEVEL.
~ 3. PROPERTY LINES SHOWN ARE BASED ON U.S ••
/ DEPARTMENT OF AGRICULTURE FOREST f SERVICE-ALASKA REGION PUBLICATION NO.
103. "PRINCE OF WALES ISLAND ROAD SYSTEM.
TONGASS NATIONAL FOREST".
4. ESTIMATED TOTAL ACREAGE OF U.S. LANDS
WITHIN THE PROJECT BOUNDARY ON THIS
EXHIBIT IS 3114.1 ACRES.
SCALE 0
EXHIBIT_K_SHEET..!.OF ....!..
TIlls drawing Ia a pari 0/ tile
application far n ..... 1IIado
IIr th.IHId.,.lpd.
TIIi .... daJ af 0...1911
ALASKA POWER AUTHORITY
II, s...... Q '+,., E ...... I •• Dl'acta'
2000 4000 1000 1000 10000 12 000 FT
I"· 2000 FEET
BLACK BEAR LAKE
HYDROELECTRIC PROJECT
ALASKA
DETAIL MAP
ALASKA POWER AUTHORITY
DWG. NO. 5715-6
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LEGEND:
,'°00 --3-23
FOREST DEVELOPMENT ROAD
AND NUMBER
PRoPOSED TRANSMISSION LINE
AND COURSE NUMBER
PRoPERTY LINE
ESTIMATED ACREAGE OF SECTION
INCLUDED IN PROJECT BOUNDARY
.~
II."
NOTES:
I. TRANSMISSION LINE LOCATION SHOWN
IS APPROXIMATE. PROPOSED PROJECT
BOUNDARY LINES ARE OFFSET 100'FEET
FROM THE TRANSMISSION LINE ON BOTH
SIDES.
2. TOPOGRAPHY SHOWN IS A REPRODUCTION
OF USGS QUADRANGLE SHEETS B-3. A-3.
CRAIG. ALASKA. THE CONTOUR INTERVAL
IS 100 FEET. DATUM IS MEAN SEA LEVEL.
3. PROPERTY LINES SHOWN ARE BASED ON U.S ••
DEPARTMENT OF AGRICULTURE FOREST
SERVICE-ALASKA REGION PUBLICATION NO.
103. "PRINCE OF WALES ISLAND ROAD SYSTEM.
TONGASS NATIONAL FOREST".
4. PROPOSED TRANSMISSION LINE CONNECTION
TO HYDABURG DISTRIBUTION SYSTEM IS SHOWN
ON FIGURE K-3.
5. ESTIMATED TOTAL ACREAGE OF U.S. LANDS
WITHIN THE PROJECT BOUNDARY ON THIS
EXHIBIT IS 59.0 ACRES.
EXHlBlT_K_SHEET'!"OF'!'
TIIIo dro.tng Ie a part '" "'.
,,",IC.,_ ... II .. _ .....
..,,_ ............ d. TtIIa-..., af J;IIt. 1111
ALASKA POWER AUTHORITY
b, s,...... A y,.u. ElocuIl •• Director \
SCALE 0 2000 4000 6000 8000 10000 12000FT 1iJI"'"_-
1"·2000 FEET
BLACK BEAR LAKE
HYDROELECTRIC PROJECT
ALASKA
DETAIL MAP
ALASKA POWER AUTHORITY
DWG. NO. 5715-7
RESERVOIR AREA IN ACRES
300 200 100
1800
.............
!
1700
....... "-~ .......... ~ .. -
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i=
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.oJ w
1500
........ ,
~ ...........
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~ ~ ............. ,
~
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I
1400
o 10,000 20,000
RESERVOIR STORAGE IN ACRE -FEET
1..--tAR."'Z.A E,..."GINE.l:.RI"'G COf\.ltPA".IY • MARCH 1981
........... ......
..
EXHIBIT K-7
o
I I
1800
I I EL. 1721 Max W. S .
__ EL. 1715 Max N orm W.S.
rm W.S. EL. 1685 Min No
1700
I-w w u..
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1600 z
0
i=
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" ,
"
W
.oJ w
1500
1400
30,000
BLACK BEAR LAKE.
HYDROELECTRIC PROJECT
ALASKA
RESERVOIR
AREA -VOLUME CURVES
~A POWER AlfTHORITY
DWG. No. 6716-8
DWG. No. 5715-9
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CRAIG
HYDABURC
LEGEND:
-----PROPOSED TRANSMISSION LINE
----EXISTING DISTRIBUTION SYSTEM
~ PROPOSED SUBSTATION
A EXISTING GENERATING FACILITY
-----TOWNSITE BOUNDARY
------MUNICIPAL BOUNDARY
I. LOCATION OF PROPOSED TRANSMISSION LINES
AND SUBSTATIONS ARE APPROXIMATE.
2. TOWNSITE AND MUNICIPAL BOUNDARIES
AND EXISTING DISTRIBUTION AND
GENERATING FACILITY LOCATIONS ARE BASED
ON COMMUNITY MAPS PREPARED FOR THE
ALASKA DEPARTMENT OF COMMUNITY
AND REGIONAL AFFAIRS. APRIL 1981.
3. EXISTING GENERA TOR OWNERSHIP:
TLINGIT & HAIDA REGIONAL ELECTRICAL AUTHORITY (THREA)
ALASKA POWER & TELEPHONE COMPANY (APD
•
1
BLACK BEAR
LAKE PROJECT
EXHIBIT K-9
SOUTHEAST ALASKA
KEY MAP
C::'~ Nd~ fiNN)
.• U.5Icv linr fioom KltlwocI<
SCALE 0',",iI!_!!!!Iiii;!;'!!0~Oiiiiii~80i!i0~!!!!12!10~0i;;;;;iiiil~6l!00~~2!i00~Oiiiiiiiiiii2~400 FT
1"-400 FEET
BLACK BEAR LAKE
HYDROELECTRIC PROJECT
ALASKA·
TRANSMISSION LINE SUBSTATIONS
ALASKA POWER AUTHoRITY
DWG. NO. 5715-10
-------------------
-
---
-
-----
---
BLACK BEAR LAKE HYDROELECTRIC PROJECT
FERC NO. 5715
EXHIBIT L
. GENERAL DESIGN DRAWINGS
OF THE PRINCIPAL STRUCTURES
ALASKA POWER AUTHORITY
ANCHORAGE, ALASKA
---
BLACK BEAR LAKE HYDROELECTRIC PROJECT
-EXHIBIT L
--Table of Contents ------
Sheet 1 of 5 Genera.1 Plan -Sheet 2 of 5 General Profile -Sheet 3 ot 5 Dam, Plan and Section -Sheet 4 of 5 Dam and Penstock, Sections --Sheet 5 of 5 Powerstation, Plan and Sections
-
Appendix A Geology
-Appendix B Project Description
Appendix C Project Design -
-
-
-
-
-
-
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HYO~ BEAR LAKE LECTRIC PROJECT
ALASKA
GENERAL PLAN
ALASKA POW ER AUTHORITY
DWG. NO. 5715-11
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BLACK BEAR LAKE
HYDROELECTRIC PROJECT
ALASKA
GENERAL PROFILE
ALASKA POWER AUTHORITY
DWG. NO. 5715-12
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BLACK BEAR LAKE
. HYDROELECTRIC PROJECT
ALASKA
.100 120FEE
DAM, PLAN a ELEVATION
ALASKA POWER AUTHORITY
DWG. NO. 5715-13
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SECTION A-A
AI18IJ1T1ed f'oolr liM
SeeptJge coll:Jr.
slJgff¢8'ID 1concret. !tiled
SECTION AT PENSTOCK ANOSHAfl
TYPICAL PENSTOCk SECTION
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TypICAL TUNNeL SECTION TYPICAL PENSTOCI{ SEC710N
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SECTION 81-81
IR "ml:? requ,;,ed
lining Ihicltnel8
6~oiwnint11 s/lQff
exco"RI"",li/W
TYPICAL SHAFT SECTION
J"./!O
SCALE 0
IIiiiiII
EXHIBIT_L_SHEET'!-OF i.
Thlt drawing I. a part of Iho
appllcallon for ncenM .. ado
by Iho undo"lgnod.
Thlt da, of 1981
AL~KA POWER AUTHORITY
bJ . 9ft l ~ ,> EXKutlvl Director
10 --20 30 40
(EXCEPT AS NOTED)
BLACK BEAR LAKE
HYDROELECTRIC PROJECT
ALASKA
50
DAM a PENSTOCK, SECTIONS
ALASKA POWER AUTHORITY
60 FEE
!
DWG. NO. 5715-14
n
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29'
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Flow -
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PLAN
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SECTION A-A
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TAIUYATER RATING CURVE
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EXHIBIT_L _SHEET iOF ~
Till. drawl .. I, a pori of Ih'
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fbi. do, of 1981
ALASKA POWER AUTHORITY " s.-B ~,.,JJ. E .. eullvo Dlreelor
SCALE IN FEET
12 18 24
3/16" -I'
BLACK BEAR LAKE
HYDROELECTRIC PROJECT
ALASKA
POWERSTATION.
PLAN a SECTIONS
ALASKA POWER AUTHORITY
30 36
DWG. NO. 5715-15
-
----
-...
-...
------------------...
--
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BLACK BEAR LAKE HYDROELECTRIC PROJECT
FERC NO. 5715
EXHIBIT L
APPENDIX A
GEOLOGY
ALASKA POWER AUTHORITY
ANCHORAGE, ALASKA
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BLACK BEAR LAKE HYDROELECTRIC PROJECT
EXHIBIT L
Appendix A
GEOLOGY
'Iable of Contents
Purpose and Scope
Regional Geology
PhysicgraJ;:hy
General Geology
~ectonics and Seismicity
Geology of the Project Site
Previous Studies
Present Investigations
Stratigraphy
Cver1:urden
Lithologic Nomemclature
Rock Lithology
Structure
Bedding
Jointing
Faulting
Ground Water
weathering
LA-i
Page
LA-l
LA-l
LA-l
LA-2
LA-3
LA-4
LA-q
LA-q
LA-5
LA-5
LA-7
LA-8
LA-9
LA-9
LA.-9
LA-l0
LA-l1
LA-l1
I
Table Q! Contents (Cont'd) I
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Page
Engineering Geology LA-12 I
!A-12
E LA-12
General
Gravity Dam and Spillway Foundations
Penstock, Shaft and Tunnel LA-13 E
Shaft LA-14
Tunnel LA-llJ E
Powerhouse LA.-15
Foundation Grouting LA-15 I
LA-16 ,
LA-lb .. Drainage
Reservoir Rim Conditions
LA-lb I "
Construction Materials
Seismic r:esign LA-l1
Recommended Design Exploration LA-18 E
Selected References LA-19 I
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Fi91!re No.
LA-l
LA-2
LA-3
LA-4
LA-5
g§! ot Figures
Composite Fegional Geology Map
Site Geology Map, Damsite
Geologie Section, A-AI
Site Geology Map, Penstock Alignment and Powerhouse
orogenic Belts and Major Fault Systems in Alaska
LA-iii
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BLACR BEAR LAKE ~YDROELECTRIC PROJECT
EXHIBIT L
Appendix A
GEOLOGY
Purpose and Scope
~his Appendix describes and evaluates the geologic conditions
of the project site and provides the basis for the preliminary
layouts and design of the proposed civil structures. The data and
analyses herein are based on a review ot geologic literature, and
limited geologie mapping and subsurface exploration performed in the
tield during July and August 1980. Approximately 300 feet of core
drilling in seven holes, fourteen shallow test pits, and 1250 feet
of seismic retraction survey along 5 lines were completed.
Petrographic analyses were pertormed on seven samples taken from
outcrops and drill cores.
Req~onal Geoloqy
The proposed Black Bear Lake Hydroelectric Project is located
on and immediately downstream ot Black Bear Lake near tne town of
Klawock in central Prince of Wales Island, Alaska. The project area
is in the west central portion of the Craig C-3, Alaska,
7-1/2 minute U.S.G.S. Quadrar.gle. Access from Ketchikan is by boat
or plane to Klawock, and up to Black Bear Lake by float plane or
helicopter only. .~ccess by foot is very difficult.
The region is an extension of the Coast Range of western North
America whiCh extends from Califorr.ia north to the Alaskan
Peninsula. This region is ty~itied by interconnected mountain
ranges 'Nhich have undergone several episodes of folding, faulting
and igneous intrusion resulting in extremely complex geolcgy. The
geology also is complicated by a system of strike-slip faults with
large horizontal displacements. Some of these faults are considered
active. ~he structural grain of tbe area trends predominantly to
the northwest and is believed to be tne result of the latest period
LA-l
of major folding and faulting during Mesozoic time. Previous
folding was either obliterated during this period or had the more
dominant trend superimposed upon it.
The project site is located on the northeast flank, and close
to the crest, of tne Prince of Wales geanticline, which is a large
structurally positive feature occupying the whole of Prince of Wales
Island.
The physiography of the project area is rugged mountainous
terrain of high relief rising to almost 4000 feet on an unnamed peak
adjacent to Black Bear Lake. The chiet mechanism in the formation
of the present terrain has been Wisconsinian glaciation causing the
development of "U" shaped valleys with steep sides and broad gentle
valley bottoms. !he relatively small mountain glacier, which
created Black Bear Lake was truncated by the valley glacier which
eroded Black Lake valley and developed a hanging valley at the
outlet of Black Bear Lake, between the proposed damsite and the
powerhouse location.
The relatively short geologic time since the retreat of the
glaciers (approximately 10,000 years) caused the drainage system to
be poorly integrated. Immature streams flo~ through oversteepened
valleys ~itn steep gradients in the upper portions of the drainage,
and through shallow lakes and muskeg in the lower portions where
gradients are much flatter.
The oversteepening
of debris avalanches and
discontinuous and are
rainfall conditions.
General Geol2.9Y
of valley sides is evidenced by many scars
rock falls. These scars are surficial and
probably caused by freeze-thaw and higt
References 1, 2, 3, and 4 were the principal sources of
information used in the present stUdy to establish an understanding
of the geologic framework of the project region and area. These
published maps and reports indicate disagreement in some details of
the geology, however, there is general agreement in the broader
aspects as described briefly here.
Sedimentary, volcanic, and intrusive igneous rocks are found
throughout the region and have occurred in at least four geologic
periods including the Ordovician-Silurian, Jurassic, I·ower
Cretaceous and Lower Tertiary. Lithologies include thick sequences
of metamorphosed Paleozoic and Mesozoic marine clastics, limestones
and volcanics intruded by igneous stocks, dikes and plutonic masses.
Volcanism has occurred intermittently since the early Paleozoic.
This is indicated by tne common interbedding of volcanic rocks
within the older marine stratigraphic sequence. Younger dikes found
within the project Site are ot diabasic to aplitic composition.
LA-2
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The bedrock of the project site is essentially Ordovician-Silurian
undifferentiated volcanics and meta-sediments. The Descon Formation
is described in the literature as a sequence of variably interbedded
marine sediments and volcanics which has been subdivided into five
general lithologic units. ~he most prominent sedimentary unit of
the formation is a fine to coarse grained graywacke and banded
mudstone. Considerable thicknesses of undifferentiated volcanics
and intrusive igneous rocks are found at th~ site area.
SOils of glacial origin including tills, fluvioglacial and
glaciomarine clastics are widespread regionally. Other soil
deposits of alluvium, colluvium, talus, and residual soils occur
locally and are widespread. Rock falls and debris avalanches are
common in places and are typical of steep-sided valleys in glaciated
terrain.
Tectonics and Seismicity
Faulting in the region is common and well developed, generally
parallel to the gene~al structural (anticlinal) grain that trends
northwest. Other faults trending north and -west are also described
regionally, but they are often based on airphoto interpretation.
The amount of displacement along faults is undetermined. Cne large
thrust fault trending northwest and passing through Klawock Lake is
shown on the GeologiC map of the Craig C-4 Quadrangle to be located
5 miles to the southwest of the project site.· Due to the limited
scope of the present study, the existence and potential hazard of
this nearby fault could not be verified. Its displacement is not
known, but is considered to be large since Pennsylvanian sediments
and the Ordovician-Silurian Descon Formation are juxtaposed.
Several major taults occur ir. the region and account tor ~uch
of the seismic activity in southeastern Alaska. These faults are
predominantly strike-slip in character, and displacement is
considered to be large (see Figure LA-S). The largest and most
seismically active ot these taults is the Fairweather-st. Elias-
Chugach Fault which -occurs approximately 80 miles west of the
project site. Movement along tnis tault is believed responsible tor
many of the large earthquakes in the region.
The Denali-Chatham Strait Fault passes through Southeast Alaska
along Chatham Strait and occurs about 80 w.iles ~est of the project
site near its intersection with the Fairweather-St. Elias-Chugach
Fault. The Denali-Chatham Strait Fault, although apparently less
active, is believed to have some earthquake activity associated with
it, predominantly toward its northern end. The area of southeastern
Alaska is seismically active with earthquake magnitudes recorded up
to a maximum of 8.1 (Richter Scale). The project Site, although
some distance trom the concentrated earthquake epicenters, could be
subject to severe shaking. Additional discussion of the seismicity
of the project is located in the section on Seismic Design.
LA-3
~Qgy of the Project Site
Previous Studies
Most of the early geologic investigations in the area were done
in association with mining activity in the early 1900's. Chief
among th€s~ investigations are A. H. Brooks (1902), F. E. wright and
C. W. Wright (1906), and A. F. Buddington and Theodore Chapin
(1929). Recent works by W. H. Condon (1961), and C. L. Sainsbury
(1961) cover the more immediate area but are also based mostly on
mapping of areas close to tide water. These later studies were
based on aerial photo interpretation, and very little field work was
done in the interior of Prince of Wales Island because of its
inaccessacility and rugged terrain. The most recent maps were
completed by Sealaska Corp., Ltd. in 1911-19 (Reference 2) and in
Reference 3 (1915), as well as the work contained in U.S.G.S.
Bulletin 1284, Paleozoic stratigraphY in the Northwest Coastal ~
of Prince ot Wales Island Southeastern Alaska by G. B. Eberlein and M: Churkin~r. (1970) • This work was located northwest of the
project site but the formations established in the a~ove waps and
reports are used herein. ~he Black Bear Lake project site was
visited by Harza Engineering Company personnel on a reconnaissance
level study in July, 1979 and a report was prepared for tne Alaska
Power Authority titl~d ~lack Bear Lake Project, A Feconnaissance
Report (Cctober 1979), Reference 1.
Present Investigations
The scope of the geologiC investigations conducted during the
summer ot 1980 are stated here. The tindings of the investigations
are discussed ~n detail in the aFpropriate sections of this report.
Revie~ of available geologiC publications
project area was completed and the references are
selected References which follow the text.
relevant
listed
to the
in the
Surface mapping in the project area was undertaken to delineate
the Site geology and determine its stratigraphic relationship with
the regional geology mapped in adjoining areas by others for
minerals studies. Detailed mapping of the regional area has not
been done except along coastal areas. Most maps available have been
compiled by use of aerial photographic interpretation. Eecause of
limited exposure due to heavy growth of timber and underbrush, only
scattered rock outcrops could be found with essentially no
possibility of locating geologic contacts demarking the lithologic
changes tetween outcrops.
A regional map (Figure LA-1) was produced from published
composite maps and some tield Checking. Site geologic maps and one
LA-4
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geologic section shown as Figures LA-2 r 3 and 4 were produced from
outcrop mapping and subsurface borings and test pits r supplemented
by seismic refraction surveys.
A total of fourteen test pits were excavated by hand to
determine the character and depth ot overburden and ~edrock type.
Pits were dug on each abutment of the dam r at the intake for the
shatt tor tne penstock r and at the powerhouse site. The locations
are shown on Figures LA-2 and 4.
A total of seven drillholes were completed r six at the damsite
and one at the powerhouse location. The borings were cored lAX-size
(BQ-size equivalent) with a two-man crew and a Winkie drill ,rig
which could be dismantled into two pieces and each section carried
by two men. Hole depths varied from 20 teet to 60 feet.
The seismic refraction surveys were completed by C. C. Hawley
and Associates r Inc. of Anchorage r Alaska wno also subcontracted the
core drilling to salisbury and Dietz r Inc. of Spokane r washington.
~hree lines were run at the powerhouse area to determine depth to
rock. 'Iwo lines were run on the left abutment of the damsite to
determine apparent thickness of the talus deposit and the apparent
bedrock r:rofile.
Stratigraphy
Overburden. The overburden at the project site is extremely
variable with respect to type r extent r depth and location relative
to the various project features. At the damsite and the upper
portions of the slope above the penstock r the overburden is
indicated to be relatively thin except for locally thick
accumulaticns of talus. At the powerhouse and along the lower
portion of the slope above the penstock r thicker deposits of
overburden can be expected.
The most widely distributed overburden is a variable r but
relatively thin veneer of humus. The average depth is abou't 2 feet r
but locally thicker accumulations over 3 teet have been encountered.
The thickness of the humus is based on the depth of incised gullies r
windfalls and test pit excavations. Very often this organic
material lies directly upon rock due to glacial scouring of previous
soil material. In other places the humus has aeveloped over talus r
alluvium r colluvium and glacial till.
~arge areas ot talus are developed at the base ot steep slopes
due to the mass wasting of rock. These deposits are locally quite
tnick. The talus is also extremely variable in particle sizer
ranging from less than 3 inches to greater than 3 feet. For the
most part these talus accumulations appear stable and have slope
angles close to or slightly exceeding the angle ot repose ot about
33 degrees.
LA-~
Most of the left abutment above EI. 1b95 teet (approx.) is
covered by a thick talus deposit which is exposed up to the base of
tne left abutment clift at about El. 1850. The depth of the talus
was found to be 35 feet in drillhole LB-3. Based on seismic
refraction survey lines No. 1 and 2, the thickness of the talus
increases toward the downstream and toward the left a~utment cliff.
The bottom of the talus, based on the seismic survey and
drillhole LB-3, appears to be a bedrock low. ~his bedrock low
considered in conjunction with the high rock knob adjacent to the
present river channel, the topographic trench on the downstream left
bank portion, and an abandoned waterfall observed at approximate
EI. 1430 on the downstream right side of the river channel could
represent a previous lake outlet prior to the deposition of the
tal us deposi t.
Talus deposits of unknown depth are widely distrituted above
the powerhouse location on the right bank of Black Creek, up to
EI. ,!:bOO feet and upstream to the base of the slope ever the
penstock. These deposits are tnought to extend under the valley
alluvium found at the powerhouse site based on drillhole PH-l. This
hole encountered 6 feet of alluvium underlain by 22 feet of angular
to subangular diorite boulders and gravel. Based on the Single rock
type encountered in drilling this lower interval, it is considered
unlikely to be alluvium and has been interpreted to be talus.
Talus depoSits at tbe base ot steep rock faces occur along the
penstock route particularly at approximate elevations from
13bO to 1280, and b50 to 500. Several large rockfalls are exposed
in the southeastern corner of Black Bear ~ake.
Finer-grained colluvium occurs on slopes at the damsite and
along the slope above the penstock route. These deposits are
composed of gravel and sands with some sand-silt fractions. The
colluvium is often relatively tnin but some locally thicker deposits
occur.
On the left abutment approximately 400 to 500 feet downstream
trom the proposed dam axis, several large dissected colluvial
depOSits are exposed which are undercut at their toe by the river
and are considered active and potentially unstable. 'l'he vegetation
has been removed by a recent slope tailure and the exposed colluvium
is lying at 51 degrees, well above the usual 33 degree angle of
repose. Its instability is also increased because of poorer
drainage due to a greater percentage of silt and sand-size
particles, as compared to the talus.
Thick deposits of glacial till in excess of 15 feet were tound
in the lower valley below Black Bear Falls and in side valleys
flowing into Black Bear Creek. The till is light to medium brown,
poorly scrted, gravelly, silty sand. Due to the presence of the
till in the lower slopes of the vall€y as well as the generally
thicker colluvium and numus accumulations in that area, it is
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expected that the thickness ot the overburden along the lower
reaches of the slope above the penstock will exceed 15 feet in
places. 'Ihe till however, was not generally tound above EI. 700.
Residual soils developed from in-situ weathering of bedrock
occur only in scattered areas at the damsite. Generally these soils
are less than one foot thick and are composed of silty clays with
gravel size tragments of relatively tresh rock.
Many tree trunks on slopes are bent, confirming the occurrence
ot down-slope creep ot the overburden layer. However, this creep
may not be a prevalent condition since per£ectly straight trees also
occur. ~he stability of these soils is enhanced by vegetation
cover.
Alluvium above the Falls, composed of boulders ar.d coarse
gravels in the upper reacbes of Black Bear Creek, is not expected to
exceed 3 or 4 teet in thickness based on the abundance of rock
outcrops downstream of the proposed axis. In the lower reaches of
Black Bear Creek below the Falls the alluvial deposits are probably
ot considerable depth. Drillhole PH-1, drilled in the approximate
center of the proposed powerhouse area, penetrated 34 teet of
overburden and was abandoned due to caving prior to encountering
bedrock. Drillhole PH-1 encountered b teet ot angular to subrounded
fine gravels and coarse sand with very few fines. This material is
Similar to that exposed in test pit .14 nearby. The material below
a depth of b teet is considered talus. seismic refraction surveys
indicate the overburden to range from 30 to 50 feet in thickness
throughout the proposed powerhouse location. The thickness of
alluvium overlying the talus is unknown except at PH-1.
Because of the short distance of transport and the high stream
gradient, tew fine sizes are present and toe alluvium typically
consists of angular to sub-rounded boulders and gravels of diorite,
andesite and metavolcanics. However, approximately one mile
downstream from the proposed powerhouse location, the stream bed is
composed ot well sorted medium to fine sand, because of a flattened
stream gradient.
The proposed powerhouse location is on a straight line
immediately downstream from a sharp bend in the river. This change
in river direction might indicate the occurrence of an older buried
channel. Such an abandoned channel is also indicated by the
relatively deep overburden encountered in PH-1, by the
interpretation ot talus underlying alluvium, and by the topographic
bedrock low interpceted ir. seismic line B-B.
LithologiC Nomenclature. During the
megascopic rock descriptions were applied to
rock types observed in drill core and
microsco~ic petrographic analyses ot selected
LA-7
field work preliminary
the complex geologiC
outcrop. Subsequent
samples in Chicago
have shown that the original field nomenclature required some
revisions. The lithologic nomenclature used in the text of this
report, and on the geologic plans and cross section reflect these
changes from argillite to a high grade metamorphic rock and
andesite. However, the descriptions in the geologic logs have not
been changed and retain the preliminary terminology applied by the
field geolcgist.
Rock lithology. The bedrock of the project area is cowposed of
andesite, tine to medium grained metamorphosed gray~ackes and
mudstones and coarse grained volcanic gra~acke, conglomerates and
breccias, allot whicn are considered to be part of the Ordovician -
Silurian Descon Formation. These rocks have been intruded by
igneous rocks of diorite to quartz diorite composition and are
assumed to be Jurassic -Cretaceous in age. In places the rock has
been subjected to regional metamorphism as well as some contact
metamorphism and metasomatism adjacent to these instrusions. Quartz
veins are wide spread although not abundant and appear to be related
to the diorite -quartz diorite intrUSion.
The principal rock types in the site area range from olive gray
to dark gray, fine to coarse grained metamorphosed graywacke and
volcanic andesite. These lithologies are exposed throughout most of
the right abutment above elevation 1750 and in the river downstream
of the Froposed axis. The graywacke is thick bedded and highly
indurated. Due to recrystallization, the rock has a tendency to
break across grains rather than around them when ~roken with a
hammer. The graywacke is extremely variable in color with crown to
gray varieties which are probably due to a change in mineral
constituents or a change in grain Size, or both. The graywacke
often grades imperceptibly into a conglomeratic graywacke in which
clasts of volcanic rocks and euhedral to angular pyroxene grains up
to 1/2-1ncn in diameter are extremely prominent. Tnese two
varieties of graywacke have been combined for mapping purposes.
Andesite is well e~posed in the river channel downstream from
the dam a~is, and on the left abutment cliff acove the talus slope.
Drillhole data, as shown on Geologic Section A-A (Figure LA-3),
indicates that the andesite underlies the overburden over most of
the dam axis area.
The andesite is typically medium gray, fine-grained, dense,
very hard and strong. It contains phenocrysts ot plagioclase,
hornblende, and pyroxenes, and includes numerous thin quartz veins
and quartzose masses as seen 1n the drillhole core. It is iron
stained where weathered.
Close to the intrusive contacts most rock types show
some degree ot metamorphism. The graywacke and particularly the
conglomerate phases sho~ a large degree of recrystallization and
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coarsening ot grain size. Tne rock becomes lighter gray and
distinctly more siliceous, ~nich is also notable in the andesite.
Rocks of intrusive igneous origin occur throughout the project
area. Diorite is probably the predominant bedrock type in the lower
valley. It occurs at the base of cliffs up to at least elevation
600 feet above the powerhouse on the right and left banks of Black
Bear Creek, and up to elevation 900 Leet along the penstock, at the
damsite and above lake elevation along the south and west shores.
One small outcrop of closely fractured, moderately weathered diorite
is exposed approximately 300 fe~t downstream of the powerhouse site.
The igneous instrusions are quite variable in composition
ranging from diorite to quartz diorite and possibly grancdiorite.
The amount of mafic minerals is highly variable. The rocks are
medium grained, generally evenly textured, light to medium gray,
hard and strong. 1\ distinct "salt and pepper" appearance is evident
as the percentage of mafic minerals increases. In areas where the
igneous rocks intrude the graywackes or andesites, they are
distinctly more mafic and tend toward a dark gray color.
Quartz veins are common in the area of the intrusions, and
pyritization is very common. The outcrops of country rock adjacent
to the intrusions and especially in the river near the proposed dam
axis are often deeply stained red to brown because of oxidation ot
the pyrite. In many areas, especially in the finer grained
andesite, a film of pyrite is present on almost all tracture faces
and parallel to the apparent flow structure.
Structure
Bedding. Due to the limited and scattered bedrock out.crops,
bedding is generally not readily observable. Eedding appears to be
quite massive and is best observed in the coarse graywacke
conglomerate where a crude stratification of pebbles is developed
and by tlow bandi.ng in ttle andesi.te. In general, the strike of the
beds is to the northwest with a dip to the northeast. This trend is
contormable with the regional structure. No detinite tolding was
observed in the area because of the limited outcrops.
Jointing,. Jointing in the project area is extremely variable
with respect to strike and dip. Tne most common joint sets are N
50 0 -10 0 wand N SOD-bOO E with generally steep but variable dips. 1\
minor concentration of joints also occurs slightly east and west of
north.
Some stress relief joints were observed parallel to existing
slopes along the slope above the penstock. These relief joints
cause a slabby breakage and spallin~ of the rock slope, but are not
LA-9
everywhere evident. Some irregular nearly horizontal jointing also
occurs in some areas.
SOme joints appear to be relatively tight, and joint fillings
are common. The most ubiquitous filling is pyrite which is commonly
weathered to reddish brown limonite. Other joint tillings include
quartz, calcite and a green chloritic material but these are greatly
subordinant to pyrite/limon1te infillings. The chloritic material
weathers to a brown clay.
The northwest-trending joint set is well developed along the
river channel near the proposed dam axis, subparallel to the stream.
The joints dip steeply to tne southwest and control the form of the
right bank of the channel in several areas. ~his northwest
orientation is similar to that exposed in a closely fractured zone
on the left bank approximately 1000 teet downstream of the proposed
axis.
Faulting. No positive evidence of faulting was observed in the
immediate area of the proposed project features; however, there is
evidence of shearing on the upper lett abutment downstream of the
damsite area. Some previous ~orkers 1/ have mapped a fault of
regional extent through Black Bear Lake and Black Lake Valley (shown
on Figure LA-1), but no absolute evidence of this was found at the
site. This previously mapped fault could be the one observed during
previous investigations by Barza in June 1919.on the west side of
Black Lake, where andesite and diorite are exposed in faulted
contact.
~he closely fractured and sheared zone exposed on the left
abutment was observed about 1000 feet downstream of the proposed
axis. !his shear zone along with the fractured and slatby diorite
outcrop near the powerhouse may be related to the fault postulated
by others 1/ (shown on Figure LA-1). The shear gouge 20ne is 0.5 to
1 toot wide with some pyrite mineralization exposed in an area of
closely spaced fracturing. The fractures are oriented about N 55 W
with a dip of 10 0 -85 0 SW. This same fractur~ orientation is exposed
near the proposed powerhouse area but these two zones cannot be
correlated along the same alignment.
A Small fault ot unknown displacement was found on the left
bank of Black Bear Lake about 2/3 mile upstream of the propcsed dam
axis. In this area, a calcite and quartz-filled zone approximately
1 to 2 feet wide is exposed with widely differing strike (across the
lake) and dip observed on oPPos1te sides of the fault. The presence
of these vein minerals suggests that this is an inactive fracture
zone.
1/ Reconnaissance Geology field maps prepared for SEALASRA CORP.
by ~erry, Michener, Booth, 1917, 1918, 1979.
LA-10
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Ground water
Ground water at the proposed dam axis is about 25-30 feet below
the ground surface. Water level measurements indicate a normal
condition with the gradient sloping toward the river. The
groundwater level at the dam axis is somewhat deep, probatly caused
by the dewatering effect of Black Bear Falls gorge and the steep
slopes immediately downstream. The groundwater level found in
drillhole PH-1 in the proposed powerhouse location was found to be
at a depth of about 25 feet The groundwater levels encountered in
the drillholes are shown on the drillhole logs and on Figure LA-3.
weathering
Weathering of bedrock is not prominent in the project area.
The most readily observable weathering phenomenon is red-trown iron
staining on the jOints and fracture surfaces due to the oxidation of
pyrite. This staining is common to a depth of 10 feet to 12 feet in
drill core, and occurs at greater depths along isolated, more
closely fractured intervals. This phenomenon is observed in outcrop
along the river channel downstream of the proposed dam axis.
Weathered rock surfaces generally are less than 1/8" thick.
However, minor jOint-controlled zones of more deeply weathered and
slightly decomposed rock occur sporadically and at depth.
Coatings along open joints are most commonly iron minerals.
Occasionally calcite and a green chloritic material is present up to
a thickness of 0.4 inch. Many joints are filled with quartz and are
little affected by weathering. The occurrence ot clay along joints
is uncommon except in a few isolated instances observed in
drillholes LB-l and RB-3.
LA-11
Engineering Geology
General
The proposed dam, spillway and penstock are to be founded on
metamorphosed sedimentary and igneous rocks described under Geology
of the proj~ct Site. These rocks will provide a suitable foundation
for the proposed structures. The project layout is shown on
Figures LA-2 and 4. Generally the rocks are very hard, strong and
fresh to very slightly weathered. Tte rocks are tYP1caily massive
to thick bedded. JOinting is moderately to slightly developed and
varia~ly spaced.
~he powerhouse will be founded on alluvium
determined from the indicated depth of overburden
orillhole and seismic refraction surveys done at
location.
and talus as
sho~n in one
the proposed
Cored drillholes and hand-excavated test pits, supplemented by
seismic refraction surveys, provided data as to rock quality, depth
of weathering, and depth of overburden at project structures, as
~ell as groundwater levels and apparent rock permeability. The
follo~ing sections present the engineering geologic evaluation for
the civil structures.
Gravi!y Dam and SFillway Foundations
The dam and spillway foundations were investigated by surface
geologic mapping, Test Pits 1, 2 and 8-12, drillholes RB-1, 2 and
LB-l, 2, 3, and by seismiC refraction surveys. These structures
will ~e founOed on interbedded andeSites, metamorphosed graywackes,
and diorite. ~he rocks that comprise the foundations are well
exposed in the narrow steep-sided gorge cut by Black Eear Creek
downstream ot the outlet of Black Bear Lake, and in a fe~ scattered
surface exposures on the abutments, predominantly on the right
acutment. The rock exbibits thick to massive relic bedding or
layering ~hich appears to dip upstream and toward the right abutment
at 400-800.
~he most prominent rock types penetrated in the drillholes are
massive, moderately fractured andesite and diorite. Drillhole LB-l
encoUntered a maSSive, fresh, moderately to slightly jOinted diorite
at a depth of 35 feet which is also exposed in the river channel.
Drillhole RB-2 encountered a microcrystalline, white quartzose zone
at 9 feet and a greenish-gray and red-brown metamorphosed graywacke
at a depth of 26 feet.
For the dam, intake shaft and spillway foundations, it will be
necessary to excavate all overburden and weathered bedrock into
LA-12
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sound bedrock. The depth of overburden is generally 3 to 7 feet
except for tne 20 to 30 teet thick deposit of talus on the left
bank. ~he amount of rock excavation is expected to te relatively
minor, based on examination of drill core where the depth of
weathering is seen to extend about 2 feet below the top of bedrock.
Nominal dental treatment of open cracks or badly fractured zones
will be required along the dam foundation.
water pressure tests in the drillholes located along the
initial axis downstream of the present dam axis indicate that the
iron-stained joints are generally tight and should not permit
excessive reservoir seepage. Isolated weathered jOints and more
closely fractured intervals encountered in drillholes caused a loss
of circulation tluid during drilling and will have to be treated by
grouting. Bedding does not appear to have any adverse effect upon
the foundation for the proposed structures and should not constitute
a preferred path tor leakage.
Careful excavation of weathered rock is required to prevent
excessive damage to sound foundation rock from blasting. Some
scaling ot the steep lett bank clitf well above the elevation of the
dam may ~e required to remove any large hanging slabs or loose
blocks.
Because of the depths ot ground water at the damsite, little
inflow is expected during excavation. Surface runoff must be
controlled by an adequate interceptor system because of the high
rainfall during the rainy season.
penstock, Shaft and Tunnel
The intake, per.stock, shaft, and lower slope was investigated
by drillhole RB-3, ~est Pits 3 to 7, and observation of limited
bedrock exposures during surface reconnaissance of the slope down to
the powerhouse. The reconnaissance was made to determine the
teasibility of constructing the penstock along the surtace of the
steep slope.
Overburden depth along the upper portion of the penstock from
the dam site to elevation 700 is not expected to be more than 2 to
3 feet. Rock outcrops are scattered and, except on clitf faces, are
best exposed in gullies and areas formed by windfalls. The
overburden is generally limited to humus with only minimal residual
soil/colluvium from weathering of bedrock. JOinting in bedrock is
variably oriented and moderately spaced. Otten the top of rock is
smooth and parallel to the slope due to glacial scour. Stress
relief jointing developed parallel to the slopes, and in part due to
unloading from the retreat of glaCial ice, occurs in local areas and
causes slabby breakage from cliff faces. ~hese observations of
difficulties in founding a stable penstock along the steep slope led
to conSideration of an underground system.
LA-13
Along the lower portion of the slope above the penstock, from
elevation 700 to the powerhouse, rock outcrops are scarce and
overburden is expected to be deeper. In the lower slopes glacial
till is expected to occur below the colluvium and humus, and depths
to bedrock of more than 15 feet are to be expected locally. A deep
accumulation of talus can be expected at the base of the steep rock
faces.
Along the penstock route in the river valley between the toe of
the major slope and the powerhouse, the depth of overturden and
talus is expected to be considerably deeper than on the slope
itself, and spread footings and burial of the penstock conduit may
be necessary.
Shaft. Based on limited knowledge of the rock strata through
which the vertical shaft will be drilled, it is anticipated from
surface reconnaissance that generally sound, hard quartzite, layered
metamorphosed graywacke or andesite, and finally diorite will be
encountered in tnat order. Zones of tractured and closely jOinted
rock can be expected. To avoid large stress relief joints, the
shaft and tunnel should be located a minimum of 200 feet from the
edge of the gorge.
Drillhole RB-3 was locdted at the proposed intake area tor the
vertical shaft and showed 2.4 feet of soil and weathered rock
fragments overlying a zone of quartzite rock down to final depth of
20 feet. ~he full thickness of the guartziteseam is not known. It
is recommended that a deep exploratory nole be drilled as a pilot
hole prior to construction, to determine the stratigraphic sequence
and potential difficulty of drilling a large diameter hole for the
shaft.
It is thought that generally good hard to moderately hard r~ck
conditions will be encountered during drilling, and that only minor
problems of stability in fractured rock can be expected.
~unnel. The tunnel geology can only be assumed trow. limited
exposures seen on the gorge walls trom a distance, and frou a few
diorite exposures along the lett side of the lower stream channel
beyond the Falls. It appears that diorite is the major rock type
below about elevation 700 feet, but andesite or other rock types may
occur within the intrusion or along contact zones. Figure LA-q
shows the scattered outcrops mapped along the original surface
alignment.
It is estimated that about 50~ of the essentially horizontal
tunnel section will require rock bolts and mesh and/or shot crete for
temporary support in blocky or closely jointed zones; and up to 25~
of the tunnel length may require steel supports in highly fractured
and weathered diorite, including the tinal 150 feet in the portal
LA-14
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section having minimal rock cover to tne outlet. ~he rock cover
does not include the unknown thickness of overburden and talus
overlying the rock.
The final section of steel penstock leading into the powerhouse
will be cut and cover in talus and gravel deposits of unknown
grading. The trench will probably require overexcavation at the
invert and subsequent backtilling and compaction of controlled
quality pervious material.
Powerhouse
Most of the proposed powerhouse location is mantled by
relatively thick layers ot alluvium and talus. Based on the depth
of overburden to at least 34 feet in drillhole PH-1 and on the
seismic survey, the powerhouse will be built on alluvium and talus.
An adequate foundation on piling or a raft design should te provided
to prevent differential settlement. The deep groundwater level of
25 feet depth measured in drillhole PH-1, suggests dewatering
problems in this location may be minor except for the draft tube
excavation. Excavation of the interlayered sands and gravel and
replacement with compacted fill, or preconsolidation by wetting may
be required.
Foundation ~routing
Construction of a nominal grout curtain beneath the gravity dam
and spillway is necessary to control seepage and reduce water losses
from the reservoir. During dril11ng and water pressure testing i~
rock, water losses ranged trom nil to 100~ in a tew open joints and
fractured zones. Generally, losses were in the range of 1 to b gpm
but less than 1 gpm in many cases. It is anticipated that grout
consumption in general will be low.
For estimating purposes, a one row grout curta~n is suggested
full length beneath the dam and spillway with spacing of primary
holes 20 teet o.c., secondary holes at 10 feet o.c., and tertiary
holes split-spaced at 5 feet o.c. Additional split-spaced boles at
less than 5 feet spacing will be provided where required. The
average hole depth is estimated to be 30 feet (deeper beneath the
channel and gradually shorter up each abutment). Holes are to be
stage-grouted in descending stage depths.
Consolidation grouting is expected to be required in areas of
badly fractured or closely jOinted rock in the foundation. ~he
estimate should include grouting the entire length of the foundation
trench with holes staggered in three parallel rows 10 feet deep on
10-foot centers.
LA-15
Drainage
A drain hole curtain is necessary on the downstream side of the
grout curtain beneatn the dam and spillway to reduce uplift
pressures and to control any water which circumvents the grout
curtain.
The drainage curtain will be a single line of inclined holes
drilled from a gallery constructed within the bottom of the gravity
structures. Holes will be spaced on 10-foot centers and average
25 feet deep.
Reservoir Rim Conditions
The proposed operating level of the reservoir is elevation 1115
feet. This is an increase of 35 teet above the normal level of
Black Bear Lake. The lake shore was inspected for seepage potential
and slope stability. The lake is currently rimmed witn relatively
impermea~le rock mantled by thin layers of alluvial and colluvial
material and possibly some glacial tills. potential for excessive
reservoir seepage is low.
Other than some surficial slumping of the thin organic top soil
layer, no slope instability is expected. Several areas ct large
block slides and talus deposits exist but these are currently
suppo~ted below present lake level and are expected to remain stable
with the higher reservoir level.
Construction Materials
Specific sampling and laboratory testing for construction
materials were not conducted tor this study. However, it is
anticipated that the talus to be excavated from the left abutment
can be gri2zlied and possibly crushed for use as concrete aggregate.
There is a more likely potential of using the alluvial and talus
material from required excavation of the powerhouse and tailrace
area, and other sources in the vicinity of the powerhouse or at
Klawock. A complete gradation of potential aggregate materials from
boulders to medium sand exists between the powerhouse location and
approximately one mile downstream. One alluvial sample taken
approximately 500 feet upstream from the head of Elack Lake
contained a well sorted medium to fine sand.
LA-lb
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Seismic Design
The region of Southeastern Alaska is seismically active and the
Project must be designed tor seismic hazard. The largest earthquake
recorded was a magnitude B.l event which occurred in 1949 about
BO miles southwest of the site along the Fairweather F'ault. The
closest earthquake (ot unknown magnitude) occurred 74 km northeast
of the site.
Owing to the sparse population and low-level of cultural
development in Southeastern Alaska, knowledge ot the seismic
intenSity of this area is not as well developed as in the contiguous
United States.
The only "felt" earthquake reported in Klawock, during the
period 1786-1974 was a reported intenSity V associated with an
earthquake having a magnitude 6.5 that occurred 213 km from the
town. No "tel ttl reports are on record associated with the B. 1
earthquake (1949) mentioned above, but this is probably due to the
sparse population at tne time.
Based on the prOjected maximum intenSity of earthquakes (Meyers
et. ale 1976) the 1949 seismic event might have produced an
intenSity of VII at Klawock although the lack of "felt" reports
tends to lessen this estilnate. Tne same lack ot "felt" reports
associated with the B.l magnitude event is true for Ketchikan as
well.
By transposing the maximum area event (B.l) to the closest
fault with known seismic activity, would yield an event of this
magnitude along t.he Fairweather Fault at a distance of 12B km
(80 miles), trom tne Project. Using seismic acceleration
attenuation curves developed for the western contiguous States
(reference 6), and considered reasonably applicable for Southeastern
Alaska, a maximum bedrock acceleration of 0.10 g would be
experienced at the Site. gowever, because of the oversteepening of
slopes and tne common occurrence ot slides in the area, an estimate
of 0.15 9 would not be overly conservative. This acceleration is
also commonly used in Calitornia, also a highly seismic zone.
For tinal design studies, the degree ot seismic hazard will
include determination of the Maximum Credible Earthquake (MeR) which
could be expected at the project site, and the design acceleration
factor to te used for the structures.
LA-17
Recommended Design Exploration
Final design of the Project will be based on geologic and
geotechnical data acquired from additional drillholes and tests for
aggregates. In the dam area, additional drillholes will be required
to define and delineate the possibility of an old channel under the
left bank talus and location of bedrock for left abutment
foundation; to further investigate tne powernouse foundation i~ the
vicinity of the present lower river channel, and to determine the
optimum depth of the toundation grout curtain beneath the dam.
Pattern drilling should be performed to explore for bedrock
configuration beneath the powerhouse. The lower section of the
tunnel and outlet portal, as well as the cut and cover penstock
section should be explored for rock surface configuration and rock
quality.
A deep cored hole (NQ-size) ~ill be necessary at the vertical
penstock shaft to determine stratigraphy, expected rock conditions
and quality, and the existence ot taulted or sbeared rock which may
require relocation of the shaft.
Laboratory tests tor physical properties ot tne various rock
types are necessary for rock strength moduli and quality data, and
for quality tests on potential concrete aggregates.
LA-18
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Selected References
Alaska Power Authority r (1919) • "Black Bear Lake Project r A
Reconnaissance Report"r Harza Engineering Company.
Sealaska Corporation r Ltd. r (1911-19). "Reconnaissance
GeologYr Klawock Withdrawal"r Three Geologic Maps of the Black
Bear Lake Area. DerrYr Michener and Booth.
Churkinr M. Jr. and Eberlein r G.D.r (1915).
the Craig C-4 Quadrangle r Alaska"r u.s.
Pam GQ-11b9.
"Geologic Map of
Geol. Survey
Eberlein r G.D., and Churkin r Michael Jr., (1910). "Paleozoic
Stratigrapny in the Northwest Coastal Area of Prince of Wales
Island r Southeastern Alaska"r u.s. Geol. Survey Bulletin 1284.
Condon r W. H. • "Geologic Map of the Craig Quadrangle r
southeastern Alaska", u.s. Geol. SUrvey Bulletin 1108-E.
Algermissen r S.T.r and Perkins, D. M., (1916). "A
Probabilistic Estimate ot Maximum Acceleration in Rock in the
Contiguous United states".
Meyers r H. Brazee r R. J.r Coffman r J. L., Lessig r S. R.,
(1916). "An Analysis of Earthquake Intensities and Recurrence
Rates in and near Alaska"r National Oceanic and Atmospheric
Administration, NOAA Technical Memorandum EDS NGSDC-3.
LA-19
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REFERENCES':
1.
2.
Sealaska Corp. Ltd., Klawock Withdrawal Reconnaissance
Geology Maps, Nov.1977, Nov.1978 and N~v.1979.
Churkin, M. Jr. and Eberl in, G. D., "Geologic Map of
the Craig C-4 Quadrangle, Alaska, U.S.G.S. GQ-1169, 1975.
3. Condon, W.H., "Geologic Map of the Craig Quadrangle,
Southeastern Alaska", U.S.G.S. Bull.l108-B, Platel, 196!.
HARZA ENGIIlEERING COMPANY -MARCH.1981
FIGURE LA-1
STRATIGRAPHY:
QUATERNARY
Qu I Alluvium.
CRETACEOUS -JURASSIC
KJ r Diorite, quartz diorite and grandiorite.
PENNSYLVANIAN
IPzpdl Porphyritic bHalt/andesite.
I Pk I KLAWAK FORMATION: Calcareous sand,stone; siltstone; & minor limestone.
MISSISSIPPIAN
Mp
Mpl
Mplc
Mpc
DEVONIAN
Dc
PERATROVICH FORMATION
Limestone member: Thick-bedded, massive limestone & minor dolomitic
limestone.
Limestone and chert member.
Chert member: Thin-bedded
CORONA DOS VOLCANICS: Volcanic basalt with interlayered, fossiliferous
limestone.
SILURIAN -ORDOVICIAN
Isouvi
I Sad I
ISOdcij
'I /.
Undifferentiated andesitic volcanics and breccia.
DESCON FORMATION: Graywacke and mudstone with interbedded basaltic
volcanic rocks and conglomerate.
Hornfels.
svrmOLS ----
Contact, approximate, queried where inferred. /' '.0' /.
/'
Fault, dashed where approximate, queried where inferred, dotted where
hidden.
/
j(I' y
Thrust fault, dashed where approximate, queried where inferred, dotted
where hidden. Barbs on side of upper plate.
Inferred fault from photogeologic mapping. Taken from reference 3.
Strike and dip of inclined beds.
Strike of vertical beds.
Strike and dip of schistosity. Scale 0
I
2 Miles
I NOTES: Contour interval 100'
1.
2.
Geology taken from reference 1 except where
locally adapted from references 2 & 3.
Topography from U.S.G.S. Craig C-3 and (-4
7~' Quadrangl es, 1949.
ALASKA POWER AUTHORITY
BLACK BEAR LAKE PROJECT
COMPOSITE
REGIONAL GEOLOGY MAP
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HARZA ENGINEERING COMPANY -MARCH,1981
--...
~~ __ -----------____ $90
Qt ~/700 -------
___ ----/710
_-----,720
FIGURE LA-I
ITUT IIIUI'HY
Grn.1 and ItOyld'rI; ..,gullr to lub .... "I.".
-OItl, dtorUe; Pnttc1e .he fro. 3 hell" to
l fUt. I Oal l~llUVIU": Sand and , •• 11 grn.l;"ftlll flnu; ."tvllr to
subround.d. sind t, COnlt.
CRETACEOUS ."d JIMASSIC
~!§IUOUU!TAUSIVU: Dlorltei •• dlu_-g"'!"'''; ltght to
•• dtu. grty; .ott1ed 10cll1y. "nd, strong.
SILURIAN Ind OAOOVICI.ut:
SOuvl~~ IUTAVOLCAMICS: Undifferentiated ",dnttle
1I'Iot f'ow. wtth ftlgll ~rlde ".gloul •• tI.orp"'c
fabrics and .In,ratsi Mfcroc,"y!';t.llln. to 'I'ft.-
g,.11 fled. gr. 1 to dl rlt grll. 111'1 til ph.noC",! t;
contatns nu •• rous qUlrtz veins; ur, liard ",d
strong.
u:=J ANDESITE: Microcrystalline, dlrlt grll.
[TI .. flOESI.l!.: Flne-gr.lfled •• ,diu. grlY·
I SOd I METASEDIMENTS: Grayweek •• highly Mt .. orphond; r.ltc
stdt.ent.ry flbrl" r ... gt fro. ftne~grltntd
.udSione to co.rse·grllned .nd conglo.tr.tle;
11gllt gr.y to bllck. IIIrd; strong.
Contact •• pprOlli.'te, queried where Inferred.
lithologic conUct betwetn " ud B .e.bers of
SOuv, qutrted when inferred.
Strtlc.t .nd dip of relic beds.
Strike .nd dip of I"d Ined joht.
Strike of vert lral Joint.
location of rock Outcrop ,rta,
location of surflce seep.
location of vertical corellole.
location of tltc1lned corellole sllowing Inclin.tlon
,nd beerlng.
anaY Loc.tlon of ttlt pH.
~ Loculon of seis.lc line, l! Loution of geologic sect ton,
NOTES:
1. See Figure lA·4 for gto1091 of penstock .11gn.tnt ud powerhouse',
2. See Figure l"·3 for cross·uctlon A.",t
3. Are.s not sllow" IS outcrops or Qt .re covtred wUh slope WlSlI.~
colluvfu •• nd vegetation,
Stille 0 25 50 F •• ,
I ! , I I It, ! ! I
Conto"r inl.r".1 2'
ALASKA POWER AUTHORITY
BLACK BEAR LAKE PROJECT
SITE GEOLOGY MAP
DAMSITE
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MARIA IJIOttIIEAING CC*PANY.IlARCH. ,.1
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LB-1
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Scale 0 10 20 30 F .. t NOTE :
F1CJUIIE LA-a
1_~~_~~~: Angular blocks and boulders of andesite.
~~~.~JL~}JJl!L_~~Q~~.~A_S~. TOPSOU:..: Silty clay to clayey silt: organic, some fragments
and boul ders.
CRE.T_AC~OLJ~ and _4LJIlA~EC
\":.1<J,':-\
"salt and pepper"; hard; strong.
~OI~_~_~~I_~_~_~n_~._!'1ilA~OJ~_~~_~: Undifferentiated andesitic lava floits; high grade
regional metamorphic fabrics and minerals; microcrystall ine to fine·gra1ned;
gray to dark gray; itith phenocryst, contains numerous Quartz veins; very
hard and strong.
Grayitacke; highly m.etamorphosed; relic sedimentary fabric and
minerals; fine·grained; dense, hard.
_____ ? Contact; dashed ithere approximate; queried ithere inferred.
I Orillhole showing drillhole "umber and projection if not on sectlon line.
Groundlllater level measured in drillho\e.
ALMItA POWER ~ITY
BLACK RAR LAd PROoIICT
1. See Figure LA-2 for section location. ~ a8()l.OGIC Qlt0881181!1CMt1i_
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POWERHOl/SE
CtIIIl_ i".".,,1 2'
HARZA ENGINEERING COMPANY -MARCH,1981
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SCIII. p, , , 100 200 Ftlll
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PENSTOCK ALIGNMENT
ClJfJlw" i~1 10'
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QUATERNARY
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FIGURE LA-4
EXPlMATlOI
6,...",1 .. , ".'d.r.~ ",.ular to ... b .. ' .... ,. ••• ,Uy
dlorUI' Plrtic •• Itu fro. 3 ind'i' to , flit.
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lultro .. nd.d, .... , t. c •• r ...
CIIITACIM ... JURAI"C
~II.(OVS "ndIlYls: Diorite, .'Iu.·,rth,d, It,1It tI .'1 ••
1,.1,; Httl.d loull,i ... rd. Itr ••••
IIL'-IAII ... OI!!!OVICIAII:
ISCllNI ,OLeAIICS .,,' JUTA'DLCAIICS: UII,Uflr,.thted ...... IUe h'll
flo ••• U" M,II ,rid' re,toul I!"!UHrpJl'c flbrl"
and .tnenh; .tcrocrJ'Ullltn, to 'I"I-,rlta,d.
grlY to d,rt ,r". wUh pll."ocrJ'st; cORUh,
n ... trou. qUlrtz 'th'., 'fIr), hlrd •• d stron ••
[::!:] AIDESllE: "ferocrJ'.tallht. d.rk IrIY.
~ fLOII BRECClA/AGLONERAn:
I SOd IRETASEDIRUTS: Grl), •• ch; hfghl, .,U_rph.oll'. rtllc
. s.d'_IIUr)' flbrlc. r ..... fro. flltl-Irlhtd
... dsto". to cOlrn-grlinld ud conglo_rlllte;
It,lIt grl, to bllek; lIerd; strong.
NOTES:
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s...~
8-
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Cont.et •• pprO:lI.,tl. qUlrled .tlere Inferrld.
Lltftolo,le contlct bltween A ud C .I.tlers of
SOu,. qUlrtld _lIere Inferred.
/
Strtlte ud dip of reI te bldl.
Str1lr.e end dip of inclinld Joht.
Stral of .,lrtlCII Jotnt.
Loc.tlon of rock out.erop ,rll.
Lotltl~n of lurhCI Ilip.
Loe.t.lon of "lrtlCII eoreftoll.
Lotltlon of Inclined eorefto1e Itlowlng Inclll11tton
ud bearln,.
Lotltlon of tett ptt.
Loeltton of sets.te 1 he .
1. See Figure LA-2 for glology of th' d •• sUe.
2. Area.s not stlown " roek outerop, or " .rl.S
of talus or .lln-fu. Ire eoured by vegetation.
topsoil. eolluvlu_ end Ilope WISh.
ALASKA POWER AUTHORITY
BLACK BEAR LAKE PROJECT
SITE GEOLOGY MAP
PENSTOCK ALIGNMENT
AND POWERHOUSE
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Orogenic belts and major fault Iystems in Alaska.
Prjnce William Sound Earthquake 0/1964
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BLACK BEAR LAKE HYDROELECTRIC PROJECT
FERC NO. 5715
EXHIBIT L
APPENDIX B
PROJECT DESCRIPTION
ALASKA POWER AUTHORITY
ANCHORAGE, ALASKA
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BLACK BEAR LAKE HYDROELECTRIC PROJECT
EXHIBIT L
Appendix B
PFOJECT DESCRIPTION
Table of Contents
Location and Access
Project Setting
General ~escription
Project Arrangement
Project Functional DeSign
Geology ot Foundations and Construction Materials
Description of Project Facilities
Concrete Dam and Spillway
Power Intake
Penstock
Power~lant
Access Roads
Switchyard and Transmission
Reservoir
Land Ownership
Recreation Facilities
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Page
I.B-1
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BLACR BEAR L~KE HYDROELECTRIC PROJECT
EXHIBIT L
Appendix B
PROJECT OESCRIPTICN
Location and Access ---
The Black Bear Lake Project is located at latitude 570 33'N and
longitude 132 0 52'W, near the town of Klawock on Prince of Wales
Island in Southeast Alaska. The Project develops the head between
Black Bear Lake and the bottom of a falls at the outlet of the lake.
The lake discharges into Black Bear Creek which flows intc 83 acre
Black Lake about 1.5 miles downstream from the powerhouse site.
Black Lake is drained by a small stream which flows about 3.5 miles
to Eig Salt Lake, an arm of San Alberto Bay.
Both present and proposed access to Black Bear LakE and the
damsite is by float plane. Present access to the powerstation site
at the base of the falls is by logging road to Black Lake and from
there by foot. The logging road will be extended to the
powerstation for construction and operation of the Project.
Project Setti!}g
Prince of Wales Island has rolling, rugged mountainous terrain
rising to 3,800 teet at Pin Peak which is adjacent to Black Bear
Lake. The Black Bear Lake valley was glacier formed, having steep
sides and a broad base.
The climate of the project area is largely maritime with
occasional incursions of continental air masses. The climate is
mild and humid with much precipitation. Average annual terrperature
is Qoo-Q50 F with lows ranging from slightly below 0 0 F in the
winter to highs close to 90 0 F in the summer. PreCipitation varies
greatly with location and tends to increase with elevation. In the
coastal towns of the project area, mean annual precipitation is
about 120 inches.
Vegetation in the project area is typical of hemlock-spruce
coastal forest with some muskeg areas. Wildlife in the project area
include black bear, deer, beaver, marten, mink, otter and wolf, as
well as many of the 200 bird species common to SOlltheast Alaska.
LB-1
Black Bear Creek is catalogued as an anadromous fish stream and
supports spawning runs of pink, chum, coho, and sockeye salmon.
Dolly Varden, cutthroat, and steelhead trout are reported in Black
Bear Creek. Rainbow trout are reported in Black Bear Lake and in
Black Bear Creek downstream of the project site.
General ~riEtion
project Arrangement
A general plan and proposed proj~ct boundaries of the Black
Bear Lake Project are shown on Exhibit K, Sheet 2. A more explicit
site plan and general profile of the Project are shown on Exhibit L,
Sheets 1 and 2 respectively.
!he Project consists of the following principal elements:
a.
b.
c.
d.
A concrete gravity dam across the outlet of Black Bear
Lake, with rock embankment support of the left abutment.
An uncontrolled
design discharge
maximum reservoir
is El. 1715. O.
spillway in the center of the dam with a
capactity of 1680 cfs. The normal
level established by the spill~ay crest
A 3-port intake, with ports at different levels for water
temperature control, and a gated emergency outlet conduit,
located on the upstream tace of the dam.
A water conduit, 4380 feet long, connecting the intake to
the powernouse. Tne water conductor consists of the
following in sequence from the intake:
1) A buried steel penstock, 294 feet in length, with a
diameter ot 48 incnes.
2) A concrete-ll.ned vertical
diameter and 1296 teet deep.
shaft, 48 inches in
3) An 8' x B' rock tunr.el, 1850 feet long, containing a
30 inch diameter steel penstock.
4l A buried steel penstock, 940 feet in length and
30 inches ~n diameter.
At the powerhouse a manifold will be provided to
distribute the flow to two generating units. At the dam,
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an emergency closure valve for tbe power conduit will be
provided.
A powerbouse containing the two impulse turtines and
generators, rated at 3.0 MW each, and electrical
switchgear. An adjacent switchyard will contain the
transformers and transmission line pull-off structures.
other facilities include the following:
1)
2)
3)
4)
An access road, about two miles in length, from the
end of the existing logging road at tbe outlet of
Black Lake to the powerhouse site and tunnel portal.
Transmission lines, totalling 53 miles
-connecting the Project with the load
Klawock, Craig and Hydaburg.
in length,
centers at
A new substation near Rlawock which will have the
necessary facilities to divide the single incoming
circuit from the Project into two outgoing circuits;
one serving Rlawock and Craig and one serving
Hydaburg.
Small stepdown transtormer stations at botb Craig and
Hydaburg.
Project Functional Design
7he Project will ~rovide total regulation of the outflow of
Black Bear Lake tor the production or power and energy. !he Project
will have. an installed capacity of 6 1~W and produce 23.7 GWh in an
average year. The project reservoir and access road will provide
recreational opportunities. Suitable agreements with private
landholders would be necessary to guarantee public use of some of
the pro~osed recreation facilities. Release of water from the
project ~ill be made in such a ~ay so as to ensure ~n1mum
disturbance to do~nstream resident tisheries and migrant fisheries.
LB-3
Geology of Foundations and Construction Materials
The project area was heavily glaciated during the Pleistocene
period and is characterized by rugged mountains dissected by
steep-sided broad valleys.
Bedrock consists of the Descon Formation, Ordivician-Silurian
undifferentiated volcanics, and a variety of interbedded fine-
grained metamorphosed sediments. Igneous intrusions of Jurassic-
Cretaceous age include diorite and quartz-diorite as dikes and as a
plutonic mass exposed in the lower valley. Some uplitt, tolding and
faulting have occured in the region but have never been clearly
defined or mapped in detail.
Numerous talus deposits trom rockfalls and debris avalanches,
and terrace deposits of glacial t~ll are found throughout the area.
These deposits and the lower stream gravel deposits are technically
suitable as sources of construction materials. As disc'~ssed
elsewhere in this report, use of the streambed sands and gravels is
rejected on environmental grounds. The selected source is rrocessed
excavated materials.
Soils and terrace deposits ot glacial and fluvial origin occur
thoughout the region. Most ot the slopes are covered ~ith humus,
residual soil and colluvium. Talus materials are angular, blocky
and generally poorly graded. vegetative growth and the forests
protect the soil cover on the slopes from erosion due to surface
runoff. Overtlow ot Black Bear Lake has scoured the outlet stream
channel to fresh rock.
Earthquakes are common in Southeast Alaska. Specifically for
the Black Bear Lake Project, earthquakes appear to be related to the
Fairweather Fault and the Clarence Straight Fault which are
approximately 80 miles west of the Project. The magnitude of
earthquakes which occur on the Fairweather Fault (some as great as
8.1 on the Richter Scale) indicate that the Project could t;e subject
to severe acceleration and must be deSigned accordingly.
The dam will be founded on sound bedrock. A small amount ot
o~anic soil and severely weathered and spalled rock covers cedrock
in the dam area. These materials will be stripped trom the
abutments and channel section. It is estimated that the thickness
of soil and loose rock ranges trom 3 to 7 feet. The left end of the
dam will be socketed into a portion of the talus slope.
The penstock
sound, hard rock.
shaft and tunnel will be excavated in expected
The pressure section will be concrete-lined.
The powerplant will
near the base of the slope.
be founded on alluvial gravels and talus
Large trees which could blow down on
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the plant should be cut and removed. The powerplant is located to
protect it from snow and debris.
Potential sources of concrete aggregates identified were a
quarry near Klawock, where they can also be processed, frow stream
gravels in Black Bear Creek or from processed excavated materials.
As discussed elsewhere in this report, use of streamred sands and
gravels is rejected on environmental grounds. The selected source
is processed excavated materials.
Descripti2U of the project Facilities
Concrete Dam and Spillway
A concrete gravity dam containing an ungated ogee spillway will
be constructed approximately 80 feet downstream trom the outlet of
Black Bear Lake. A plan and elevation of the dam and spillway are
Shown on Exhibit L, Sheet 3. Sectional views of these structures
are shown 9n Exhibit L, Sheet q.
The maximum height of dam will be about 39 feet on the
abutments and about 53 feet through the narrow outlet channel. The
entire foundation of the dam will be stripped to sound rock. The
dam will require about b,qOO cubic yards of concrete. To facilitate
excavation through the deep talus deposit on the left a~utment and
construction of the concrete dam, a temporary retaining wall will be
constructed at El. 1125. After concreting is completed, the
retaining wall and a portion of the dam will be backfilled to a
starle slope with excavated material.
The spillway will be located in the center of the dam. It will
be an uncontrolled crest structure with a width of 30 teet with
critical depth control occuring at the crest for a~l flows.
The spillway will be deSigned to pass the outflow corresponding
to the protable maximum flood intlow of qOOO cts. The spillway,
with crest at EI. 1115, will have a discharge capacity of 1680 cfs
with the reservoir at EI. 1121 or b teet above the normal maximum
level. The top of the dam ~s at EI. 1123.0, providing 2 feet of
freeboard above maximum flood pool.
As shown on Exhibit L, Sheet 3, spilled water will flow over
the ogee and horizontal concrete apron to a short channel in rock
and into the existing gorge.
A grout curtain will be constructed under the dam. This will
serve to negate or reduce the increased seepage and seepage
p~ssures which will result trom the raised lake level. The grout
LB-5
holes of the curt.a.in will be angled to intercept a greater number of
steeply deeping joints.
It is estimated that a seepage control grout curtain averaging
30 feet deep (deeper beneath the channel and gradually shorter up
each abutment) should be adequate. It is also recommended that
spacing should be 20 teet on the abutments and split to 5 feet or
less where required. Two to five rows of consolidation grout holes
may be required in highly fractured areas. These holes would serve
to reduce uflift pressure and also to consolidate the fractured
rock.
Power Intake
As shown on Exhibit L, Sheet 4, a multiport intake structure
with three gated orifices will be located on the upstream face of
tne dam in the deepest part ot the existing outlet channel. The
l' x l' ports, with inverts at El. 1612, El. 1683, and El. 1693 will
be automatically operated to provide temperature control for power
discharges throughout ttle range of headwater fluctuations.
Trashracks will be provided for each port. Water passing the
trashrack will have an average velocity ot 1.3 tps through the gross
area at the maximum expected discharge.
The intake
reservoir to El.
the intaj(e.
will be SEt low enough to permit drawdown of the
1b85.0 while maintaining adequate sutmergence of
Water for power production will pasR trom the appropriate port
through the dam to the 48" g power conduit via the
7'-0" x 1'-0" bell mouth entrance and transition section (from
rectangular to 48 inch diameter) •
An automatic, motor operated 48 inch diameter butterfly valve
located at the toe of the gravity dam will provide positive shut off
of the power tlow, if required.
The greatest quantity of bushes and trees around Black Bear
Lake are located near the dam on natural benches that will be
inundated at the proposed normal reservoir level. Because these
benches will be cleared during construction it is expected that
little trash will reach the intake. Intake velocities will be less
than 2 feet pEr second so the lowest intake port can be set close to
the bottom of the short approaCh channel without the danger of rocks
r.eing carried into it.
~n emergency outlet conduit with a manually operated gate will
also be incorporated into the intake structure. This conduit will
be b'-O" in diameter and will serve as the diversion conduit during
construction.
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Penstock
~he ~enstock which will convey flow for ~ower generation from
the dam and intake to the powerhouse has tour distinct segments; a
48 inch diameter buried steel pipe, a 48 inch finished diameter
vertical concrete lined sbatt, a 30 incn diameter steel pipeline on
saddles in an adit and a 30 inch diameter buried steel pipe segment.
A typical section through eaCh ot these segments is shown on
Exhibit L, Sheet 4.
The 48 inch buried pipeline will extend about 290 feet from the
cutterfly valve at the toe of the gravity dam to the top of the
concrete shaft. The pipeline will be placed in a trench excavated
in rock on the right abutment. The trench will then be backfilled
with excavated material. This pipeline will terminate in a vertical
bend into the concrete lined shaft.
'Ihe vertical shaft will consist of a 6'-0" nominal diameter
Circular shaft excavated in rock and a 1 foot thick unreinforced
concrete lining. The shaft will extend from EI. lbbb.O to
EI. 370.0, a distance ot 1296 teet. Access to the bottom of the
shaft will be by an 8' x 8' modified horseshoe tunnel, 1850 feet in
length. steel access hatchways to allow inspection and maintenance
of the shaft, if reqUired, will be provided at both the top and
bottom of the shaft.
At its base, the shaft will be connected to a 30 inch diameter
steel pipeline. 'Ihis pipe will be supported on concrete saddles
throughout the entire length of the rock tunnel to the portal at
EI. 350.0.
From the tunnel portal to the powerhouse at EI. 255.5 the
30 inch diameter steel pipeline will be buried in a rock fill which
will serve as the permanent access road to the tunnel portal. The
pipe ~111 be surrounded by gravel bedding and cast-in-place concrete
thrust blocks will be provided at bends.
ThE penstock, which will be encased in the
substructure concrete, will deliver water to the two
units via a welded steel manifold.
powerhouse
generating
'Ihe various segments ot the penstock were deSigned for the
gross head at the section plus a 30~ allowance for overstress due to
water hammer. Steel portions of the power conduit will be
fabricated from ASTM A-333 Grade 6 steel which exhibits adequate
notch toughness for low temperature service. ~he wall thickness of
the steel pipeline including 0.125 inch corrosion allowance is
0.313" in the 48 inch diameter segment and varies from O.b88" to
0.750" in the 30 inch diameter segment.
LB-7
powerplant
The powerplant will have a reinforced concrete substructure,
with a superstructure of concrete and concrete block and an
insulated aluminum roof supported by a metal truss system. The
overall dimensions ot the powerplant will be 70 feet long by 40 feet
wide by 31 feet high trom generator floor to the peak of the roof.
The unit bay width will be 22 feet. A plan and sectional views of
the powerhouse are shown on Exhibit L, Sheet 5.
~he two turbines will be single nozzle horizontal impulse type
turbines rated to produce 4,300 horsepower at a net head of 1370 feet
at 600 rpm. At the rated output and head each turtine will
discharge 32 cfs.
The generator and turbine of each unit will be connected by a
horizontal drive shaft. ~he generators will be rated at 3750 kVa at
600 C temperature rise, O.B power factor and 60 Hertz. Each
generator will have a continuous overload rating ot 15% at 800 C
temperature rise above ambient.
Circuit breakers will be the air magnetic type. They will be
rated to interrupt the maximum expected fault current and will be
used to put the unit on-line during the normal start sequences.
Station service power will be supplied at 4BO-V, by 3-phase
dry-type transformer and 4BO-V circuit breakers.
All protective relays and
manual and automatic operation of
provided.
all
the
control devices for complete
generating units will be
Supervisory control equipment will be provided to permit remote
control indication, and communication ot powerhouse generating data
to a remote central control room located at Rlawock.
The powerhouse will be provided with a single light bridge
crane of 10 ton capacity. The crane, which will be supported by
steel columns and support beams, will serve to unload and erect
equipment during construction and to facilitate servicing.
other mechanical equipment including an air compressor and
emergency diesel generator will be provided in the powerhouse.
Access Road
Access to the powerhouse for construction and project operation
will require extension ot the existing logging road at the north end
of Black Lake. ~he length of the new road is about two miles.
Routing and construction of the portion ot the road along the east
shore of Black Lake will require measures to minimize the potential
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for slope failures and mass movement. The road will cross an active
slide zone near the northeast end of the lake. It is proposed that
this zone be crossed by placing a rockfill embankment in the shallo~
bay at the toe of the slide with the expectation that this portion
of the access road will require periodic maintenance.
No road would be tuilt to Black Bear Lake, which would would
continue to be accessible only by float plane or helicopter.
Switchyard and Transmission
The generators will be connected to two power transformers
located in a small yard across the access road to the west ot the
powerhouse erection bay. The transtormers will be rated at 4312 kVa
each. A single circuit 34.5 kV transmission lines will connect the
Project with the load centers at Klawock and Hydaburg. A single
circuit 1.2/12.5 kV line will connect the distribution system at
Craig to Klawock.
1he recommended transmission line routing, beginning at the
powerhouse site, wil~ follo~ the access road to Black lake and
continue along the existing logging road to its intersection with
Forest Development Road 5000, (Klawock-Thorne Bay Road). From
there, the transmission line would follow the road to a substation
constructed just east of Klawock near State Highway 924 to Follis.
From the proposed substation, one circuit would tie into the
existing Klawock system and continue along the Craig-Klawock Road,
(State Highway 924), to Craig.
The second circuit would provide service into Hydaburg. The
routing, tram the proposed substation, would ce easterly along
Hollis Road to a point approximately four miles past the
southeasterly end of Klawock Lake, where a principal logging road
intersects Hollis Road. The line would tnen run generally to the
south, following the general route of the logging road. The logging
road terminates near the head ot Natzuhini Bay. It has been
proposed that this logging road be extended another six miles to
Hydaburg. The transmission line would follow the final road route
on into Hydaburg.
A single circuit 34.5 kV line is proposed. This line would be
of horizontal linepost insulator type construction, such as the
REA Type ~P-34. ThiS type of construction, using 336.4 MCM ACSR and
45-to 50-foot poles, would provide an average span of approximately
bOO teet. This type of construction also permits for a very narrow
line path.
The insulators for this construction are 14-1/2 inches long,
for an overall width of three feet. This narrow protile will be
LB-9
more environmentally acceptable in the project area than other types
of construction.
Besides the substation at the po~~r plant site a sutstation is
needed along the Hollis Road. This substation will provide the bus
arrangement necessary to split the single incoming 34.5 kV circuit
1nto two outgoing circuits, one to Klawock-Craig at 1.2/12.5 kV, the
existing primary voltage in Klawock, and the other to Hydaburg at
3q.5 kV. !he Klawock-Craig line would be built, tapping the Klawock
line via fuses. Small stepdown transformer stations will be used in
Craig and Hydaburg to convert the incoming voltage to the primary
distribution voltage in each community.
Reservoir
The reservoir created by the dam will cover the present Black
Bear Lake, riSing up the surrounding steep sloI=es, increasing the
depth of the lake by 35 feet.
The volume below the surtace of the present lake at Fl. 1680 is
limited by a large rock mass which rises up out of the bcttom to
just below the water surtace near the center of the lake. For that
reason it was considered more economical and practical to ottain the
necessary storage for tlow regulation by providing the additional
storage atove the present lake level.
At the normal elevation ot 1115, the reservoir will have a
surtace area of 2ql acres and provide a storage volume of 6850 acre
feet tetween EI. 1115 and El. 1b85.
The reservoir will be surcharged to as high as Fl. 1121 when
tloods are discharging throuqh the spillway.
Some clearing of the reservoir will be necessary adjacent to
the dam and along the northeast shore of the lak~. Approximately
bO acres between El. lb80 and El. 1110 will require clearing. About
23 acres of the 60 will be heavy clearing, mostly of mountain
nemlock.
Land OWnershiE
The lands within the project area for the dam, powerhouse, and
portion of the reservoir (Sees. 1, 12, and 13, T.13S., R.82E, Copper
River Meridian) are presently owned by the U.S. Forest Service but
have been withdrawn under the Alaska Native Claims Settlement Act
tor selection by Klawock Heenya, the Klawock village corforation.
In addition, Sealaska Corporation, the regional native corporation
has top-tiled ~or selection ot lands which include those sections.
Neither corporation bas placed these lands as top priority for
LB-10
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conveyance and their ownership may remain with the u.s. Forest
Service if the native corporation entitlements are used els~wbere.
Project lands for a portion of the reservoir pool southeast of
the damsite lies in Secs. 7 and l8, T.13S., F.32E., Copper River
Meridian which is presently unencumbered U.S. Forest ServicE land.
!he transmission line corridor traverses u.S. Forest Service
land, private land held predominately by the Sealaska Corporation,
Klawock Heenya, Shaan-Seet, and Haida Corporation, and highway
rights-of-way owned by the State of Alaska. ~he Applicant proposes
to acquire project lands and right-ot-way through a variety of
methods as appropriate and necessary including special use permit,
leasE, purchase, or eminent domain.
Recreation Facilities
It is anticipated that recreation use of Black Bear Creek
valley will increase some~hat, principally in sport fishing use. To
accommodate this expected increase in use, fishing and boat access
to Black Lake and a tisning access trail upstream of Black Lake are
proposed. A presentation of the recreation facilities is shown on
Exhibit V, Sbeet 1.
Boat access to Black Lake will be provided by a gravelled ramp
accessible trom the proposed project access road. The access road
will be widened near tne boat ramp to provide for vehicle parking.
Two picnic tables and trash cans will be provided tor tbe
convenience of visitors.
A simple wood chip covered foot trail for fishing access to
Black Bear Creek will be proviaed approximately naIf a mile
upstream of Slack Lake. The head of the trail will be located on
tne project access road.
Also, an interpretive display eXFlaining project facilities and
operation ~ill be placed at the powerhouse. Visitors will use the
parking s~aces provided at tne powernouse. The powerhouse will be
closed except for occasional tours •
No additional recreation facilities are proposed for Elack Bear
Lake. The existing Forest Service cabin ~ill be relocated before
the reservoir is tilled.
LB-11
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BLACK BEAR LAKE HYDROELECTRIC PROJECT
FERC NO. 5715
EXHIBIT L
APPENDIX C
. PROJECT DESIGN
ALASKA POWER AUTHORITY
ANCHORAGE, ALASKA
--
-BLACK BEAR LAKE qYDROELECTRIC PROJECT -EXHIBIT L --Appendix C -PROJECT DESIGN --Table of Contents -------page
-General LC-l -Dam and Spillway LC-l -Dam Location LC-l -LC-l --Spillway LC-2
-stacility Analysis LC-2 -water Conductor LC-4 -Powerhouse LC-5
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BLACK BEAR LAKE HYDROELECTRIC PROJECT
EXHIBIT L
Appendix C
PROJECT DESIGN
General
The proposed project structures will be designed in accordance
with the American Concrete Institute's "Building Code Requirements
for Reinforced Concrete," the "Specification for the Design,
Fabrication and Erection of Structural Steel for Buildings" by the
American Institute of steel Construction, Incorporated, applicable
sections of state and local industrial building codes, and accepted
engineering practice. All materials specified for use in project
construction will be appropriate to their function with normal
design stresses. The proposed design stress and ultimate strength
of reinforced concrete are 1350 psi and 3000 psi, respectively. The
yield point for reinforcing steel is bO,OOO psi and for structural
steel, 36,000 psi. The ultimate strength of materials will be in
accordance with ASTM specifications.
Dam and 2Eillway
Dam Location
The dam is located 80 feet downstream of the existing outlet of
Black Bear Lake. This location is fixed by topographic and geologic
limitations. Shifting of dam axis upstream of tt.e present location
would Significantly increase the crest length of the structure.
Downstream of the dam, the bedrock foundation begins sloping towards
the valley below •
'Ihe selected impoundment structure for the Project is a
concrete gravity type dam. Two other types of impoundment structure
considered in the course of deSign of the dam ~ere rock fill dams
with two different types of impervious membranes. A zoned type
rockfill structure was not considered because there is no source of
impervious till material at the site.
LC-l
One of the studied alternatives ~as a rockfill ~ith a one-foot
tnick reinforced concrete slab on its upstream face. At the
upstream toe of the dam the slab ~ould be connected to a grout
curtain to complete tne impervious membrane. The second alternative
studied would incorporate a steel bin type retaining ~all structure
backed by a rockfill. Steel plates would be ~elded to the upstream
face of the bins to form the positive water cutoff. The bottom bin
would be embedded in the concrete grout curtain cap to complete the
membrane. Both rockfill dams would have a chute type uncontrolled
spillway in an excavated rock trench on the right abutment.
Rockfill for these types of dam would be supplied from required
excavation and borrowing trom the talus deposit at the base of the
left abutment.
Comrarison of initial cost showed slight ditferences between
the three alternatives with concrete gravity structure the most
economical. More significant are the probable differences in
maintenance costs between the rockfill alternatives and the gravity
dam. For the concrete faced rockfill, it is likely that cracks
would form in the thin membrane due to settlement of the supporting
rockfill after reservoir filling. Corrosion protection and possible
cracking at tne welds due to settlement would be of continuing
concern for the steel bin type rocktill dam. Repair of such defects
at this remote site would be costly. The concrete dam would not
require maintenance ot a comparative magnitude.
Considerations of performance under earthquake conditions also
support the choice of the concrete gravity dam as the recommended
structure.
Spillway
'I.tle spil.l.way is located in tne center ot the gravity dam and
founded on the rock knob which forms the left bank of the present
stream channel. DOWnstream of the dam the stream channel turns to
the left minimizing the length of the spillway disc~arge channel.
'I he uncontrolled ogee type gravity section with a short concrete
apron ~as deSigned to discharge lb80 cfs witn b teet of reservoir
surcharge. with its crest set at El. 1715, the spillway l\"ill pass
the probable maximum flood with the reservoir high ~ater surface
reaching El. 1721, leaving 2 feet of freeboard.
Stability Analysis
'Ihe concrete gravity dam, spillway and intake were investigated
for stability and resistance to sliding on the foundations. The
maximum vertical stresses at tne heel and toe of the structures were
also computed. The results of these studies are shown on
Figure IC-1.
LC-2
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• ...
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•
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~he method used for evaluation ot each structure'S stability
and foundation stresses conforms to standard engineering practice
and technique. Investigations were made for the following loading
conditions:
CASE I Construction Condition dead load only, with no
water loads or uplift pressures.
CASE II Normal Operation Condition normal headwater
elevation, full uplift on base, plus ice loading.
CASE III Inspection Condition intake "later passages
CASE IV
CASE V
un~atered with normal headwater elevation and full
uplift on rase.
Project Design Flood Condition -design surcharges on
headwater and tailwater elevations, plus
corresponding uplift.
Earthquake Condition Case II loads plus seismic
loading but without ice loading.
The magnitude of
analysis is 10 kips per
the normal head~ater
thrust ~as based on the
the pressure exerted by ice assumed for the
linear toot across the face of structures at
elevation. The choice of this value for ice
geographic location of the Project.
~he earthquake acceleration was taken to be 0.15 g based on the
geographic location of the Project.
structures on rock foundations are considered safe against
overturning if the resultant or all forces fall within the middle
third of the base width of the structure (no tension allowed between
concrete and foundation) in Cases II and III. In Cases I and IV,
the resultant is allowed to fall ~ithin the middle 0.4 of the base.
In Case V, the resultant is allowed to tall within the middle balf
of the base. For these cases it is assumed that only compressive
stresses can be transmitted to the foundation and that the portion
or the base in tension is inefrective. For Cases I and IV this
results in 0.9 of the base ta~ing the load and in Cases V, 0.15 of
the base taking the load. Allowable compressive stresses on
fOUndation rock are estimated to be 150 ksf. For drained horizontal
sections in concrete and for drained rock formations (with a Single
line ot drains), the uplitt pressure is assumed to act over
100 percent of the base. At the drain line, the uplift pressure is
assumed to equal to full tailwater plus 1/4 of the difference
between headwater and tailwater. From the drain line, the pressure
varies as a straight line to full headwater at the upstream edge and
to full tailwater at the downstream edge.
LC-3
Resistance to shearing and sliding was computed using the
• ..
• lilt
following shear triction formula: ,
where:
Safety factor, Q = fv + Ac
H
t = friction factor (0.15 for nard sound rock and concrete.)
v = algebraic sum ot all vertical loads.
H = algebraic sum of all horizontal loads.
c = ultimate cohesion strength of foundation rock or concrete.
A = area ot base under compression.
With appropriate values inserted tor the loads and resistive
forces, the shear friction safety factor "Q" applies to any section
of the structure or its foundation. The plane of analysis for this
investigation was taken at the base ot each structure. The shear
friction safety factor for concrete water retaining structures on
rock toundations should not be less than 3.0 for loading Cases II,
III, and IV and not less than 2.0 for Case V.
As snown on Figure LC-1, for every loading case conSidered, the
resultant ot torces on the dam, spillway and intake falls within the
required middle zone of the base of each structure. For all cases,
the shear friction factor is above the required minimum values and
the base pressures are all well below allowable limits.
water Conductor ---
Water conveyance is by a single conduit which is buried in an
open cut excavation or in a rock shaft and tunnel throughout its
entire length. ~he conduit diameter is 4.0 feet to the base of the
vertical shatt portion and 2.5 teet in diameter thereafter.
The 2'-b" diameter of the major portion of the penstock was
selected based on economic studies of conduits ranging in size from
2'-0" to 3'-6". The diameter of the vertical concrete lined shaft
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is 4'-0" to facilitate access during construction. In the portion
of the penstock between the dam and the shaft it was decided to
continue the 4'-0 diameter. This decision was based on
consideration of possible expansion of the Project to a 3 unit
peaking plant at some time in the future. Expansion would entail
tapping the 4'-0" shaft at its base and installing a new penstock to
conduct lIiater to the new unit. Providing a '1 1 -0" diameter trom the
dam to the shaft would facilitate such project expansion at a small
additional cost to the presently proposed Project.
A surface penstock route was considered as an alternative to
the recommended route. Field investigation and subsequent office
studies reveal several problems which cast doubt on the long term
viability of this alternative. The surtace routing investigated
generally parallels the stream alignment dOllin the heavily timbered
slope on the right bank. The large trees along the route have
shallow root systems and pose a threat to a surface pipeline. In
order to lessen this threat, the penstock would be buried to just
below the rock line along most of its length. Clear cutting to
protect a surface pipeline was rejected because of the possibility
ot creating a landslide or snowslide channel along the route.
Construction of the surface penstock would require installation
of a high line. ~his facility would then also be used for
construction of the dam and appurtenances and would ~e left in place
for future access to the upper Site. Anchorage of the pipeline at
major bends would be difficult because ot .adverse bedding of the
rock.
Although preliminary cost comparisons showed the underground
routing to have a first cost exceeding that of the surface route by
about 15%, the underground route was selected because it is expected
to be a more stable structure, requiring a minimum amount of
maintenance. Additionally, the underground penstock route is
considered to have a significantly lesser environmental impact than
the surface route.
Powerhouse
~he ~owerhouse is located on a deep talus deposit on the right
bank of Black Bear Creek. The concrete raft foundation will provide
economical sup~ort for this structure. The powerhouse
superstructure will be of reinforced concrete and reinforced
concrete block construction. These materials were chosen over the
less expensive prefabricated metal alternative for security reasons.
Since the plant will be unattended, no windows will be provided,
also as a security measure.
LC-5
the powerhouse and access road will be protected from
infrequent floods by rock berms and channelization ot the creek in
their proximity. ~he generating equipment is set at an elevation
above tlood stage.
As an alternative to the recommended powerhouse location, an
underground powerstation location was considered. This scheme was
rejected because it was determined to be as costly as the surface
structure while incurring a reduction in net head for power
production of about 60 feet.
LC-b
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---:..::z::::_----=--
Flo"" -
~r:'~~tiC.'
r;"s",; --V
I i ri"s ~~ .. 1 RI.f:l6
]Z 6[1.06
.TIT. ! 48.21 ; .y.' I 69.06
Horillont.1
~H
Kips
0.00
4(J.00
M.38
47."
his o/concret.
g,.."ity d.m
£Topofde",EI.I7IS;D
MOmMts Base Pressure
About KSF
Pf.A,Z AlA
Ft. Kips Heel I roe
827.0 5.41 ) 0.20
1342.4 0.04 . 4.69
873.6 0.117 2.84
IZ56.1! 0.63 4.09
Shear Location Of
Resultanf Fricl/on ·X·Feet Factor From Pf. A
NA. 10.09 .-17.09 19.43
18.37 18.12
/4.37 18.19
LEN r.o T HAN A L Y Z E D-/~O·
Percentage Of
The~/n Case
Compre$sion
100 I --'Orr-II
10.0._
/00 1-llZ"
Z
Flow -
Vertical Horizont.,
.lEV .lEH
Kips Kips
101.19 0.00
86.3'.1 48.28
83.86 52.53
86.39 60.16
A1fis ., c_,..fe
gr."ity dtJM
£Topofd.m EU72!1.0
Moments &se Pressure She.r About
Pf.A,.E AlA KSF Fric;ion
Ft. Kips H~I Toe Fac;or
994.1 6.87 0.00 N.A-
1668.4 0.45 5.27 14.83
1580.5 0.69 4.87 13.59
1654.9 0.54 5.19 1/.90
LEN G T HAN A L Y ZEDs I~O'
Loc.tionOf
hsulhlnt,
·x·Feet
From Pt. A
9.82
19.31
18.85
19.16
Flow -
Min. W. S. £ll685. 0
I'rN'cent.gtl Of
The &se In Case
Compression
97.8 I
100 II
100 III
100 IY
JL
::::; F / L L WA Y-A '" A L Y 51 5 ArE L. 16.9 4.0 D A M-A N A L Y 5 I 5 ArE L. 168 0.0
A. L OADINt3 CA5f:S
I-Cone;ruction Condifinn-Sfructur. comple;e, dl'<ld
I_donly.
]I-.... , Operatin, Cn"difion-lIfNId"".fer EI.1715.0
Ic. to.d-/OIr~,..r iF .flU7/f.0
.-In.pee'i." Condltion(ln;"" only) HNd_fer EI.1715.0
.-Flood COIWIition-HwMIw.t.r EI.I12I.0
r-E"'/~Condifion-"--I.".t.rEI.17I5.0
~-O.l5g
13. CRITERIA
Allo_ble ftJuntJafitJn pressurfi on rock 750 lesf
Shetlr friction f.ctor-Q-(fE V+A Jtc)/£H
oW>rw f'-fric;ion f.clor-0.75
EV-sum of "erfic.IIOIIds
c-ultfm.f. cOMsion s;reng;h of f""",."01'1
rock or cone,.." -150 psi
A-IIrea of bas.
£H-sum of horizon;.ll'orces
Q should be ~ 3 for C.s.ll, III and:rr
~ 2 for Case JC
Uplift-Assumed lie ling On 100:lE> of In" Nse area and
.,-110 full hfiId"".tel' and ItJilw.l"r pressures IIf
lIN ItHIIInd loe I'Hpeclively. Af filII dr.in line upliff
ass.-.d to "" equal to full I.il"".;"r plua ~ of fhe
d~f'_nce befw"n M«Iw.ler 1Int1 f.IIIN.ler.
v.1'!1~="~
Axis of cone,..t.
,I'.vity Am
£Top of dtJm EI. 1723.0
72·ditJ. diversion conduit
.nd tlmergency oullet
FIGURE LC-I
I 1--------,f-'-'---::r4~7=!2~.__ ~48-.;·.r· ... k
Vertical Horizontal Moments iJa$e Pressure Shtlor location Of i
About Resultant . 1't:r<·"nfa9f! Of
ZV ZH Pf.A,~MA K5F Friclion "x.F~1 ' rh" Bust:! in
Kips Kips Ff. Kips Heel Toe Fllctor F~ P~A Comf'l'esslon .. ~--,-~
7993.2 0.0 163,443 6.91 0.0 N.A. 20.45 ?'J.4
6886.2 9664.1 212850 0.69 5.46 12.88 30.91 100
6566.7 3164.1 18B 933 l83 4.27 15.60 28.n 100
6868.1 4064.1 212901 0.64 5.48 12.20 31.00 100
6886.2 5024.4 227.458 0.00 6.65 6.81 33.03 95.3 --
LENG TH OF I!>A Y~50'-O"
IN TA KE-A NA LYSIS ATE L. I 6 7 0.0
BLACK BEAR LAKE
HYDROELECTRIC PROJECT
ALASKA
CONCRETE DAM
STABILITY ANALYSIS
ALASKA POWER AUTHORITY
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BLACK BEAR LAKE HYDROELECTRIC PROJECT
FERC NO. 5715
EXHIBIT M
GENERAL DESCRIPTION OF THE MECHANICAL AND
ELECTRICAL EQUIPMENT, AND THE TRANSMISSION LINE
ALASKA POWER AUTHORITY
ANCHORAGE, ALASKA
------• ---Turbines -----Generators ---.. -Transformers -Powerhouse -----Klawock ----Craig ---
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Page M-l of 2
BLACK BEAR LAKE HYDROELECTRIC PROJECT
EXHIBIT M
GENERAL DESCRIPTION OF MECHANICAL,
ELECTRICAL AND TRANSMISSION EQUIPMENT
-Number
Rating
Type
-Number
Rating
Voltage
-Number
Rating
Voltages
-Number
Rating
Voltages
-Number
Rating
Voltages
2
4,300 Horsepower at
1,370 feet net head
Impulse
2
3,750 KVA at 80% power
factor and 60°C tempera-
ture rise
4.16KV
2
4,312 KVA
4.16 KV/34.5 KV
1
3,750 KVA
34.5 KV/7.2-12.5 KV
1
2,000 KVA
7.2-12.5 KV/2.4-4.16 KV
Transformers -continued
Hydaburg -Number
Rating
Voltages
Transmission Line
Powerhouse/
Klawock -Voltage
Conductor
size
Klawock/Craig -Voltage
Conductor
size
Klawock/
Hydaburg -Voltage
Conductor
size
Intake Gates -Number
Height
Width
Outlet Gate -Number
Height
Width
Page M-2 of 2
1
2,000 KVA
34.5 KV/2.4-4.l6 KV
34.5 KV
336.4 MCM
7.2/12.5 KV
336.4 MCM
34.5 KV
336.4 MCM
3
7' -0"
7 ' -0"
1
6 • -0"
6 ' -0"
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BLACK BEAR LAKE HYDROELECTRIC PROJECT
FERC NO. 5715
EXHIBIT N
ESTIMATE OF THE COST
OF CONSTRUCTING THE PROJECT
ALASKA POWER AUTHORITY
ANCHORAGE, ALASKA
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FERC
Account
Number
330
331
332
333
334
335
336
353
355
356
BLACK BEAR LAKE HYDROELECTRIC PROJECT
EXHIBIT N
ESTIMATE OF THE COST OF DEVELOPING THE PROJECT
Summary Estimate
Item
Land and Land Rights
Powerstation and Improvements
Reservoir, Dams, and Waterways
Waterwheels, Turbines, and
Generators
Accessory Electrical Equipment.
Miscellaneous Powerstation
Equipment
Roads and Bridges
Substation and Switching Station
Equipment and Structures
Poles and Fixtures
Overhead Conductors and Devices
Mobilization and Logistics
Subtotal Direct Cost
Contingencies
Total Direct Cost
Administration and Engineering
January 1981 Construction Cost
$
Estimated
Cost
399,000
737,000
13,905,500
1,380,000
695,000
48,000
660,000
1,088,000
1,711,000
1,698,000
1,500,000
$23,821,500
4,678,500
$28,500,000
4,000,000
$32,500,000
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ESTIMATE
BLACK BEAR LAKE
BAUZA ENGINEERING COllPANY
CHICAGO. ILLINOIS
Profect HYDROELECTRIC PROJECT JANUARLY 1981 1 6 Date, __________ Page, ____ of, ____ Pages
Structure PROJECT WORKS Estimated by, __ RD ____ Checked by. __ KT_W __
..... ITEM ~ Unit PrIcI AMCIUIII No.
330 ILand and Land Rights 399 000
331 ~owerstation and Improvements 737 000
332 !Reservoir, Darns and Waterways 13 905 500
333 Iwaterwheels, Turbines and Generators 1 380 000
334 ~ccessory Electrical Equipment 695 000
335 ~iscellaneous Powerstation Equipment 48 000
336 !Roads and Bridges 660 000
353 ~ubstation and switching Station
Equipment and Structures 1 088 000
355 ~oles and Fixtures 1 711 000
1
356 pverhead Conductors and Devices 1 698 000
-~obilization and Logistics 1 500 000
Subtotal Direct Cost $ 23 821 500
Contingencies 20%+ 4 678 500 -
Total Direct Cost ~ 28 500 000
-
Engineering & Administration 4 000 000
January 1981 Construction Cost ~ 32 500 000
I
I!STIMATE
BLACK BEAR LAKE
BARZA ENGINEERING COMPANY
CBIC'&'GO. ILLINOIS
,~ HYDROELECTRIC PROJECT Dat. JANUARY 1981 Page 2 of __ 6~_Pag ..
~~ PROJECT WORKS E.timated by __ .&.>R .... D ___ Ch.ck.d by KIW .... ITEM Qu.1IIty UnltPrb Amount No.
330 Land and Land Rights
• 1 Land Purchase
.11 Reservoir and Dam 260 Ac . 1,500 390 000
• 12 Water Conductor and Powerstation 9 Ac. 1,000 9 000
Subtotal Item 330 :;> 399 000
331 Powerstation and Improvements
.1 Powerstation
.11 Diversion and Care of Water L.S. 19 000
.12 Clearing 3 Ac. 6,100 18 300
.13 Excavation -talus 1,180 cy 7.50 8 850
.14 Backfill 400 cy 6.00 2 400
.15 Substructure
.151 Concrete -mass 385 cy 690 265 650
.16 Superstructure
.161 Concrete -structural 65 cy 2,350 152 750
f-
.162 Masonry 4,560 S.F. 17.50 79 800
.163 Architectural Treatment L.S. 24 000
.164 Steel Roof Structure 12,000 1bs 2.30 27 600
.165 Roofing 3,900 S.F. 5.50 21 450
.166 HVAC and Plumbing L. S. 25 000
..:1.6 7 Miscellaneous Metal 2.500 1bs 2.90 7 250
.168 Crane Supports 24.500 1bs 2.90 71 050
Subtotal Item 331.1 ~ 723 100
.2 Station Yard
.21 Fill 6QOcv 6.00 3 600
.22 Crushed Rock 200 c~ 23.00 4 600
__ 23 Fence and Gates 200 L.F. 28.50 5 700
Subtotal Item 331. 2 13 900
Subtotal Item 331 S 737 000
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ESTIMATE
BLACK BEAR LAKE
HARZA ENGINEERING COMPANY
CHICAGO. ILLINOIS
--.--HYDROELECTRIC PROJECT Da JANUARY 1981 P 3 f 6 p ~,,,,-,_______________ te _________ age ___ o ____ ages
Structure PROJECT WORKS Eatimateel by ___ RD ___ Checkeei by KTW
..... -ITIM QuaIIIIIy Unit ...... AnNUlI No.
332 Reservoir Dams and Waterways
.1 aeservoir --
.11 Cl@arinll --
.11] H@avv 23 Ac. 8 OOQ 1184 1000
.11~ Li2ht 35 Ac. 4 .200 147 nnn
Subtotal Item 332.1 $ 331 000
.2 Dam and Spillway --
.21 Diversion and Care of Water I.S 'i7 Innn
.22 Clearin2 ~k ~200 16 Ron
.23 Excavation --
.23] Talus ] 5 3 S1l-.C..Y q 'i0 14'i R2'i
. 23~ Common 1.400 cv 7 50 In 'inn
• 23~ Rock 2.400 C'V 21.00 'i'i I ? n()
21l SUDDort SVl':t@m T .~ ~'\() nnn
.24 Fnllntl::lf"inn Preoaratio.n - -
.24] Groutin2 4.650 T . F 'io.no ..2.3.2 I-s-a£l
.24 ' Drain Holes and Drains q'in T .F ftft 'in ~'l 1'7'\
.25 ~a~kfill 17 200 ~::i 8.00 137 69Q
.26 Concrete --
.26 Mass 6 2~J:Y 4ill ? ')6::> 'i00
.26' Structural . 1 'iO ('v R'iO , ?7 'inn
.27 Miscellaneous Metals 2 000 1bs 2 90 'i Rno
Subtotal Item 332.2 Is t.. 764 4 nn
.3 Waterways --
31 Intake -
.31 Excavatinn -rock 200. C'V 4~ 00 9 900
":l.1 ' r.nnl'TPf"p structural 190cv 1.2ID ::>41 100
":l.1 r.::lf"P~ r.lIitl~~ FrameI':
AlIf"nm::lf"iC' r.nntTn11': ann Trash racks ~.£ 12q 000
3H Mi!,;I"@11 ,.n~n'tl': M@t;:r.l!'; 2.000.lhs .2 ...!In 'i Rno
ESTIMATE
BLACK BEAR LAKE
HARZA ENGINEERING COMPANY
CHICAGO. ILLINOIS
Pr~~ HYDROELECTRIC PROJECT Oate __ J_AN_U_AR_Y_l_98_l ___ Page,_4 __ of 6 Pagn
Structure PROJECT WORKS Estimated by_~RD~ ___ Checked by~K~TW~ __
..... ITIM QuaIdIIJ Unit PrIce AIDount No.
.32 Penstock --
.321 Buried Penstock --
.321 Excavation --
321111 Talus 2 ,500 cv 7 50 18 750
32112 Rock 1 050 cv 45 00 6.7 ''in
321'1 Backfill 4 100 cv 7,00 28 7nn
3211 BeddinlZ 1.000 C'v 11 nn 'H nnn
32llj ConLrete -anchor blocks 140 cv 6.9.5 91 100
32l~ Valve -48" ~Butterflv Valve 1 ea 4'iO "'i nnn
322 Shaft Penstock
3221 Excavation -rock (72"~) 1 1'i0 l'V 1 1nn 1 7'i'i nnn
322'1 Concrete Linin!? 750 C'v 1 ,gnn , 6.''i nnn
33 Tunnel Excavation and Support 1,RSOT .. F, 1,600 2 960 000
-
34 Pen~tol'k ~tee]
341 :::t::: :::::~: 30.000 1bs 3.80 114 000
342 624 000 lbs 3.80 2 371 200
35 Tailr_Clce and Existing Creek
351 Excavation -talus 2 160 cv 7.50 16 200
352 Backfill 2.100 cv 7.00 14 700
Subtotal Item 332.3 $ 9 310 100
~l1htnt:-l' Tt-em 112 $ 13 905 500
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ESTIMATE
BLACK BEAR LAKE
HARZA ENGINEERING COMPANY
CHIC .... GO. ILLINOIS
Pr~~ HYDROELECTRIC PROJECT Date JANUARY 1981 Page 5 of_-",6 __ Pages
Structure PROJECT WORKS Estimated by,_-.JR:u,OL.-___ Checked by KN
..... ITEM QuaaIIIy UnltPrb A.ount No.
333 Waterwheel, Turbines, and Generators
.1 Turbines and Governors 2 ea. 400,000 1800 000
.2 Generators 2 ea • 290,000 580 000
Subtotal Item 333 $ 1380 000
.334 Accessory Electrical Equipment
. 1 Supervisory Control System L.S • [75 boo
.2 Miscellaneous Electrical Equipment L.S. 520 boo
Subtotal Item 334 's 1695 boo
335 Miscellaneous Powerstation Equipment
.1 Powerstation Crane -10 ton 1 ea. 38.000 38 000
.2 Miscellaneous Equipment L.S. 10 1000
Subtotal Item 335 Is 4R 000
336 Roads and Bridges
.1 Access Road 2 mi. 330_,000 S 1660 boo
ESTIMATE
BlACK BEAR LAKE
BARZA ENGINEERING COIIPANY
CHIC ..... GO. ILLINOIS
Prolect HYDROELECTRIC PROJECT Dat. JANUARY 1981 P0ge, __ 6 __ of ___ 6 __ P09.S
Structur. PROJECT WORKS Estimated by __ -=.RD=-___ Checked by KTW .... ITEM QuanIIfJ Unit PrIce AMOUIII No.
353 Substation & Switching Equip. & Structures
.1 Powerstation Substation
.11 Transformers -4000 'IWA 2 each 20,000 40 pOO
1-
.12 Switches, Breakers, Bus, Misc. L.S. 350 ~OO
.2 Klawock Substation
.21 Transformer -3750 'IWA 1 each 20,000 20 ~OO
.22 Switches, Breakers, Bus, Misc. L.S. ~50 ~OO
.3 Craig & Hydaburg Substations
.31 Transformers -2000 'IWA 2 each 14,000 28 POO
• 32 Switches, Breakers, Bus, Misc • L.S. 1200 ~OO
Subtotal Item 353 $ 1 P88 POO
355 Poles and Fixtures
.1 Clearing
• 11 Heavy L.S • 1447 000
• 12 Light L.S • 665 ~OO
.2 Poles
.21 Material L.S. 230 ~OO
.22 Construction L.S. 369 1000
Subtotal Item 355 Is 1 711 1000
356 Overhead Conductors and Devices
.1 Conductors L.S. 330 000
.2 Insulators L.S. 1225 000
.3 Hardware and Miscellaneous T .. S 1222 000
.4 Construction
.41 Strinaina L .S 'fill 1000
.4' GUYs, Anchors and Miscellaneous LC£ ORR 1000
Subtotal Item 356 S 1 698 000
-Mobilization and Logistics L.S. $ 1 500 000
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BLACK BEAR LAKE HYDROELECTRIC PROJECT
FERC NO.. 5715
EXHIBIT 0
STATEMENT OF THE TIME REQUIRED TO
COMPLETE CONSTRUCTION OF THE PROJECT
ALASKA POWER AUTHORITY
ANCHORAGE, ALASKA
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BLACK BEAR LAKE HYDROELECTRIC PROJECT
Exhibit 0
The ~pplicant proposes to begin construction immediately
upon issuance of the License. The time from start to com-
pletion of construction will be approximately 2.0 years.
Figure 0-1 shows the detailed construction schedule.
0-1
DESCRIPTION
YEAR I
J F M A M J J A
AWARD •
LOWER SITE
MOBLIZATION --CAMPS a SHOPS • • TUNNEL
PENSTOCK
POWERHOUSE
CIVIL WORKS ..
MISC. EQUIPMENT
TURBINES a GENERATORS
INSTALLATION
TESTING
TRANSMISSION LINE a SUB-STATIONS
RECREATIONAL FACILITIES
CLEAN UP a DEMOBILIZATION -
UPPER SITE
CAMPS -PENSTOCK
VERTICAL SHAFT
EXCAVATION
CONCRETE LINING
BURIED PENSTOCK
DAM. INTAKE a SPILLWAY
EXCAVATION
GROUTING a DRAIN HOLES
CONCRETE
GATES a VALVE
BACKFILL
RELOCATION a RESERVOIR CLEARING
CLEAN UP a DEMOBILIZATION
RESERVOIR FILLING
S' 0 N D J F M A M
-
-
WINTER
0-Vh-V// -0 ~ ~
Vh-~ V~
'0 V~ V~
V~ V~ V~
V~ ~ 0
V~ ~/-0
~ ~ 0-
~ ~ ~
[0 ~ ~
~ Vh-~
V// V// V~
V~ V~ '/"'~
~ V~ ~
:/~ ~/-0
YEAR 2
J J A S 0
i
-
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..
...
N D
PRO JECT COMPLETE
m.T..JLsHuT.LCW...L
nil· ............ " .. ........... --....
.. ....... 1 ... .:
11iII4"" 4-l1li
ALAIKA POWU Ay'tHCIIIITY
.. l· ~~..u ............
lUCK lEAR LAICE
HYDROElECTRIC PRO.IECT
ALASKA
CONSTRUCTION SCHEDULE
ALASKA POWER AUTHORITY
-
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BLACK BEAR LAKE HYDROELECTRIC PROJECT
FERC NO. 5715
EXHIBIT R
PLAN FOR PUBLIC UTILIZATION OF THE
PROJE.CT AREA FOR RECREATIONAL PURPOSES
ALASKA POWER AUTHORITY
ANCHORAGE, ALASKA
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BLACK BF!AR T.AKr, HYDROEI.F!C""RIC PROJEC'l'
EXHIBIT R
PLAN FOR PUBLIC UTILIZATIDrJ OF THE
PROJECT ARP.A FOR RECREATIONAL PURPOSES
Exhibit R is contained in Exhibit W, Appendix W-R of this
license application.
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BLACK BEAR LAKE HYDROELECTRIC PROJECT
FERC NO. 5715
EXHIBIT S
REPORT ON THE EFFECT OF THE PROJECT UPON
THE FISH AND WILDLIFE RESOURCES IN THE AREA
ALASKA POWER AUTHORITY
ANCHORAGE, ALASKA
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Section
1.
1. 1
1. 1 • 1
1. 1.2
1. 1.3
1.2
1.2. 1
1.2.2
1.2.3
1.2.4
1.3
1.3. 1
1.3.2
1.3.3
1.3.4
2.
2.1
2. 1. 1
2.1.2
2.1.3
2.1.4
BLACR BEAR LAKE HYDROELECTRIC PROJECT
EXHIBIT S
Table of Contents
DESCRIPTION OF EXISTING FISH AND WILDLIFE RESOURCES
Species
Plants
Wildlife
Fish
Communities and Associations
Vegetation
Wildlife Populations
Aquatic Habitat Types
Fish Populations
Unique and Other Biotic Resources
Unique Ecosystems or Communities
Endangered or Threatened Species
wetlands
Estuaries
EFFECTS OF THE PROPOSED ACTION ON FISH AND WILDLIFE
RESOORCES
Construction
~errestrial Species and Habitats
Aquatic Species and Habitats
Major Ecosystem Alteration
Endangered or Threatened Species
-i-
Page
s-1
S-l
S-l
S-l
S-3
s-3
S-3
S-4
S-4
S-5
s-8
S-8
S-9
S-10
S-10
S-10
S-10
S-10
S-11
S-12
S-lb
Table of Contents (Cont'd)
Section
2.2 Operation and Maintenance
2.2.1 Terrestrial Species and Habitats
2.2.2 Aquatic Species and Habitats
2.2.3 Major Ecosystem Alteration
2.2.4 Endangered or T'hreatened Species
2.2.5 Cumulative Impacts
2.3 Termination and Abandonment
2.3.1 Terrestrial Ecosystems
2.3.2 Aquatic Ecosystems
3. MEASURES TO ENHANCE THE ENVIRONMENT OR TO AVOID OR
MITIGATE ADVERSE ENVIRONMENTAL EFFECTS
3.1 Preventive Measures and Monitoring (Protection)
3.1.1 Monitoring
3.1.1.1 Project Operation Monitoring
3.1.1.2 Aquatic
3.1.1.3 Vegetation
3.1.1.4 Wildlife
3.1.2 Preventive Measures
3.1.2.1 Minimization of Problems Due to Malfunctions and
Accidents
3.1.2.2 Protection ot Services and Environmental Values
During Maintenance and Breakdowns
3.1.2.3 Protection of Fish and Wildlife Resources
3.1.2.4 Protection of Water Quality
-ii-
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S-16 I S-17
S-24 E
S-29
S-30 :
S-31 I S-31
S-32 I
S-33 I .-
S-33
S-33 I
S-33
S-33 I
S-35 I S-35
S-36 I
S-36 I
S-3b I S-36
S-38 I
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Section
3.2
3.2.1
3.2.2
iJ.
5.
6.
Table ot Contents (Cont'd)
Environmental Restoration and Enhancement (Mitigation)
Terrestrial Habitat and Wildlife Populations
Aquatic Habitat and Fish Populations
AGENCY MEETINGS, CORRESPONDENCE, AND TELEPHONE
CONVERSATIONS
STUDIES CONDUCTED
BIBLIOGRAPHY
-iii-
Page
S-39
S-39
S-40
S-41
S-43
S-44
No.
S-A
S-B
List of ~endices
Title
Acronyms
General Design Drawings of the Principal structures
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BLACK BEAR LAKE HYDROELECTRIC PROJECT
EXHIBIT S
PROJECT EFFECTS ON FISH AND WILDLIFE
1. DESCRIPTION OF EXISTING FISH AND WILDLIFE RESOURCES
1.1 Species
1. 1. 1 Plants ----
The Project Area contains old growth forests, muskeg forest and
bogs, and subalpine vegetation. Table W-1 of Exhibit W lists the
plant sfecies common to the major vegetation types of the Project
Area.
1. 1 .2 Wildlife
Mammals
The larger mammals of Prince of Wales Island are tasically
those of comparable habitat on the mainland, except that brown bear,
mountain goat, and moose do not occur. The species present on the
island are of interest to man as game animals, as furbearers, or as
food species for other mammals and birds.
!he black bear (Ursu~ americanus) is abundant throughout the
island, including the Project Area. It utilizes a variety of
habitats, depending on its need for food or cover. vegetable matter
torms the mainstay of its diet, supplemented with fish and carrion,
as available.
The timber wolf (Canis lupus) is the only other large carnivore
on the island. It is associated with all types of natural habitat
where it can find its principal prey, deer. The latter, Sitka
black-tailed deer (Odocoileus hemionus sitkensis) is not abundant in
the Project Area, although good habitat is available. Thus, the
potential for growth of the herd is present (ADFG). 1/
The smaller mammals apparently are present in the Black Bear
Creek basin in good numbers, but quantitative field data are
lacking. Beaver (Cas!or canadensis), mink (Mustela vison) and
marten (Martes americana) are abundant along the creek. Mink and
beaver are strongly water-oriented; marten is associated closely
with mature coniferous forest. All tnree species are intensively
sought by fur trappers. The general inaccessibility of the Project
Area probably has provided some protection. Other small mammals
which occur on Prince of Wales Island include shrews, bats, red and
flying squirrels, mice, voles, weasel and land otter (ADFG).
1/ Acronyms used in this Exhibit appear in Appendix S-A.
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Birds
With greater mobility than mammals, bird species tend to be
more uniformly distributed among islands in island groups. Many of
the 212 species listed by the USFS Wildlife Task Force as "common"
in Southeast Alaska (USFS 1918b) can be expected in suitable habitat
on Prince of Wales Island. A few of the 5b species listed as
"casual, accidental, uncommon, or rare" in the region also may be
expected on the island. Gibson (1916) found about 50 species of
land birds breeding on the Alexander Archipelago, as compared with
about 15 or more on the mainland. Table W-2 of Exhibit W lists
birds known to be present in the Project Area.
Only a tew of the 2b8 species occur as breeding birds in the
Black Bear Creek drainage or elsewhere in the Project Area. Black
Lake and Black Bear Lake support a tew pairs of diving ducks, common
goldeneye (Bucephala clangula) and red-breasted merganser (Merqus
serra tor) in midsummer; both species probably breed near these lakes
or near the muskeg lakes along the proposed transmission corridor
route. Common loons nested and hatched a chick on Black Lake in
1981. The streams provide habitat tor spotted sandpiper (Actitis
macularia) , belted kingfisher (MegaceEYle alcyon) and dipper
(Cinclus mexicanus). ~he old-growth forest is the preferred habitat
for some forty-odd species of hawks and owls, thrushes, flycatchers,
sparrows, chickadees, and, especially, wood warblers. Forest
openings, whether natural or manmade, are innabited by sparrows,
finches and some warblers and viSited by some forest birds, such as
robins, seeking berries or other special toods.
The northern bald eagle (Haliaetus leucocephalus alascensis) is
an abundant year-round resident ot Prince of Wales Island. It is
seen frequently along Black Bear Creek, especially when spawning
salmon are present. Most eagle nests in Southeast Alaska are within
100 meters ot salt water so nests would not be expected near the
1nland lakes of the island. In 1980 tne area near the dam site and
reservoir was searched for a nest and none was found. This is not
surprising, since there are no large trees along the edge cf Black
Bear Lake and the lake is not accessible to spawning salmon.
Reptil~ and Amphibians
The only member ot these groups on Prince of wales Island are
the western toad (Bufo boreas) and possibly one or more salamanders
(Wood 1980). --
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1.1.3 Fish
Dominant fish species in the Black Bear Creek drainage system
are members of the salmonid tamily. The drainage system is divided
into two distinct aquatic ecosystems inhabited by different species
assemtlages.
Black Bear Lake, perched in the upper portion of the drainage
basin is inhabited by rainbow trout (Salmo qairdneri). Prior to
stocking at rainbow trout in 1956, no fish were known to occur in
Black Bear Lake. Since the initial stocking, the rainbow population
has become a reproducing population and has sustained itself with no
further stocking necessary (ADFG).
Dominant fish species in the valley stream below Black Bear
Lake include pink salmon (Oncorhynchus gorbuscha), chum salmon
(Oncorhynchus keta), sockeye salmon (Oncorhynchus nerka), and coho
salmon (Oncorhynchus kisutch) all of which are anadromous and use
the system at somewhat ditferent times.
In addition to the anadromous species, resident fish include
cutthroat trout (Salmo clarki), rainbow trout or steelhead (Salmo
qairdneri), Dolly Varden (Salve linus malma), sculpin (Cottus sp.)
and threespine stickleback (Gasterosteus aculeatus). Scul~ins and
sticklebacks occur in freSh water near the mouth of Black Bear Creek
and in the brackish waters of the small estuary in Big Salt Lake
(ADFG, Scott and Crossman 1973). Populations of both resident and
anadromous cutthroat and Dolly Varden are thought to be present, and
the anadromous form of the rainbow trout (steelhead) may also occur
in addition to resident rainbow.
1.2 Communities and Associations
1.2.1 Vegetation
The forest of Prince of wales Island is a segment of the
temperate rain torest which extends along the Pacific coast from
northern California to Cook Inlet, Alaska. Nearly all of the
Project Area is covered by this torest. the Black Bear Creek
valley mostly is covered by old-growth climax forest while the
slopes around Black Bear Lake support a more open subalpine type of
vegetation. Figure W-1 of Exhibit W is a map of the forest types
found in the Black Bear Creek valley and on the adjacent mountain
slope s. Figure w-2 of Exhibit W is a map of the vegetation on the
mountain slopes around Black Bear Lake. A detailed descri~tion of
vegetation associations is given in section 2.2.2.1 of Exhitit w.
S-3
1.2.2 Wildlife Populations
ADFG black bear harvest figures for Prince of Wales Island
indicate that about 10 bears are taken by hunters each year. Only
one of 249 bears listed by ADFG for the years 1916-19 was taken at
Black Bear Lake. Another was taken from Black Bear Creek and 11
trom the area around Big Salt Lake. The scarcity of kills from
Black Bear Lake probably is due more to the area's inaccessibility
than to a lack of bears. Bear sign is abundant in the Project Area.
~he timber wolt population is currently at a reduced level
compared to the past, as is the deer population. However, neither
species is particularly scarce in the Project Area (ADFG).
~he population of black-tailed deer fluctuates widely in
response to predation, heavy snows, disease, and hunting Fressure.
The last does not appear to be a major factor on Prince of Wales
Island. Continued timber cutting, by removing the old-growth forest
that provides winter cover, is expected to reduce deer numbers
(Meehan 1914).
The remaining land vertebrates of the Project Area
essentially unstudied. Quantitative data on furbearers do
indicate the sources of skins. Field observations by
Applicant's consultants indicate that most of the small mammals
abundant along Black Bear Creek.
1.2.3 Agua!ic Habitat Types
are
not
the
are
Black Bear Lake is a deep cirque mountain lake which collects
runoft trom the surrounding mountain walls. The outlet stream,
Black Bear Creek on the north end of the lake, falls approximately
1500 ft in 0.5 mi to the valley floor, and is impassable to fish.
From this point to the stream's mouth the gradient is moderate.
Two miles downstream of Black Bear Lake the stream enters Black
Lake, then flows for three miles to Big Salt Lake.
Black Bear Lake is 1.4 mi, long, varies in width from about 0.1
to 0.4 mi, and has a surface area of 240 acres and a volume of
approximately 22,000 acre feet (ADFG). The lake's northern basin is
shallower (maximum depth 100 tt) than the southern basin (maximum
depth greater than 200 ft). Black Bear Lake becomes thermally
stratified during the summer months.
The stream between Black Bear Lake and Black L,ake has three
zones: (1) the steep drop from Black Bear Lake; (2) a reach with
braided and intermittent stream channel and gravel-rubble substrate;
and (3) the last 0.6 mile above Black Lake where the creek is
sluggish and deep with undercut banks covered with grasses, sedges,
and shrubs. The stream chann~l here has fine sand-silt substrate.
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Black Lake is approximately one mile long and is shallow at the
upstream (south) end and deeper at the downstream (north) end.
From Black Lake the stream flows north for three miles to enter
Big Salt Lake, a saltwater embayment: pools and riftles alternate
in this reach, with some large sloughs along the bank in certain
areas.
More detailed descriptions of aquatic habitat are given in
Appendices W-A and W-B of Exhibit W.
1.2.4 Fish POEulations
Black Bear Lake
The only fish known to be present in the lake are rainbow
trout, derived from stocking in 195b of 5,000 eyed eggs su~plied by
OSFWS (Baade 1960). Before stocking, the lake was barren
(Kelly 1979). These fish spawn in the spring from April to June,
probably in shallower areas of the lake with gravel or rubble
substrate (Kelly 1980). Likely spawning areas include the shallower
areas described in Appendices W-A and W-B of Exhibit W, as well as
areas near the lake outlet in the shallower northern basin. Two or
three nine-inch fish were observed in this latter area during
reconnaissance studies in summer of 1979.
!he lake's trout population is reported to be self-maintaining
(Kelly 1979). Black Bear Lake was assigned a sport fishery rating
of 1 (lo~est on a scale from one to five) in the TLMP Fisheries Task
Force Working Report (USFS 1978). Recreational fishing in the lake
is reported as "not very good" (Elliott 1979), "slow at times"
(ADFG), and "good" (Kelly 1979).
Downstream ot Black Bear Lake ----
Black Bear Creek is catalogued as an anadromous fish stream
(No. 103-60-031) and supports spawning runs of pink, chum, coho, and
sockeye salmon (ADFG). Pink salmon is the principal anadromous
species using the stream, with a peak escapement during the last
ten years of 42,300 in 1975 (ADFG). Table W-3 of Exhibit W
summarizes ADFG escapement records for Black Bear Creek. ADFG has
identified spawning areas from the upper intertidal zone to Black
S-5
Lake and rearing areas suitable for COhO upstream and downstream of
Black Lake. Applicant's aquatic studies identified other salmon
spawning areas upstream of Black Lake, and reported other
observations on salmon use of the stream (see Appendix W-B of
Exhibit W).
Field observations in 1981 by Applicant's consultants and ADFG
indicate the following comparative estimates of salmon spawning use
of Black Bear Creek (see also Appendix W-B of Exhibit W) :
1981 SALMON ESCAPEMENT ESTIMATES
Above Black I.ake 2/
Below 1/
Black Black Bear Lake south Total Upper
Species Lake Affected System Tributary watershed
Pink 22,000 2,000 2,000 4,000
Chum negligible negligible negligible
Sockeye b50 550 1,200
Coho 200 -1,000 3/
TOTAL 2,650 + coho 2,550 + coho 5,400 -6,200
1/ ADFG aerial survey
2/ Applicant'S consultants
3/ Preliminary
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Sport fish species occurring in Black Bear Creek are Dolly
Varden char, cutthroat trout, and reportedly steelhead trout (ADFG).
ADFG classities Black Bear Creek as a "quality class 2" steelhead
stream and "quality class 2" cutthroat stream (Jones 1918). 1/ other
fish species reported include sculpin and three-spined stickleback
(ADFG).
The peak of the pink salmon run in Black Bear Creek usually
occurs in late August (De Jong 1919). Except for Applicant·s
aquatic studies, there are few data on the timing of runs of other
salmon species into Black Bear Creek. In the absence at more
detailed data on Black Bear Creek, ADFG weir counts of pink, chum,
coho, and sockeye salmon ascending the Rlawock River (seven mi
southwest of Black Bear Creek) in 1911-1980 were examined (Bates
1919, 1980; Hansen 1980). ADFG has advised that Rlawock River weir
counts can be used as an approximate indicator ot run timing in
Black Bear Creek, except that pink and chum salmon run a£out two
weeks earlier in Black Bear Creek than at Rlawock River (ReIly 1980;
Hansen 1919, 1980). Table W-4 of Exhibit W summarizes these data,
and shows that peak escapement periods in Black Eear Creek are
probably as follo~s:
Pink mid-August to late september
Chum late August to late September
Coho late August to early November
Sockeye early July to early September
Applicant's consultants, based on Kla~ock weir counts, other
ADFG information, and tield observations, constructed the following
summary table of salmonid use of Black Bear Creek acording to
speCies, activity, timing, and reach of the stream (see also
Appendix W-B of Exhibit W). Both salmon and potentially important
sport fish species are included.
1/ Class rating are "1" (highest), "2", and "other".
S-1
Species
and Activity
Pink -spawning
Chum -spa\'Vning
Coho -spa\'Vning
rearing
Sockeye-spawning
rearing
Dolly V-spawning
rearing-residence
Steel head-spawning
rearing-residence
Cutthroat-spawning
rearing-residence
SALMONID USE OF BLACK BEAR CREEK
Above
Black Lake
yes
minimal
Sept.-Nov.
continuous
August
continuous
yes
yes
possible
possible
possible
possible
Location
Below
Black Lake Black Lake
minimal Aug.-Sept.
Sept.
Sept.-Nov.
continuous continuous
minimal August (1)
continuous
over-
winter
(1)
(1)
resident
over-
winter
spawn
reside
possible
possible
possible
possible
Above
Hwy. Bridge
Aug. -Sept.
Sept.
Sept.-Nov.
continuous
spawn
reside
possible
possible
possible
possible
• •
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Based on the above and on life history information in Scott and •
Crossman (1973) ~ the important months are August through November "
for spawning (coho=September through November~ sockeye=August)~ and
the winter and early spring months~ probably through May~ for egg
incubation and intragravel larval fish above Black Lake. This time ,
range also covers these activities tor pink and churn salmon. •
1.3 Uniq~~ and Other Biotic Resources
1.3.1 Unique Ecosystems or Communities
Plants
No unique plant communities are found in the Project Area. All
plant communities present are well-represented throughout
southeastern Alaska.
Wildlife
There appear to be no unique wildlife communities or ecosystems
in the immediate area of the Project.
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Aguatic
There are no unique aquatic ecosystems or communities in the
Project Area.
1.3.2 Endangered or Threatened Species
Plants
No plants species officially classified as either endangered or
tnreatened for Alaska (Murray 1980) are known to occur in the
Tongass National Forest (Muller 1980).
Muller (1980), in a survey of the threatened and endangered
plants in the Tongass National Forest, lists eleven species
considered "sensit:ive" for this area. These species are listed in
Table W-5 of Exhibit W. Six of tne eleven species are officially
classified as rare, status undetermined, for Alaska (Murray 1980).
Tnese species are known only from tvpe specimens or from one or more
collections at the type locality. Additional information is
required, therefore, to evaluate their taxonomic or geographic
status. ~hey would appear to be rare but this is subject to change
after further studies. In addition to the six rare species, five
other species are listed a-s being "sensitive" for the Tongass
National Forest (Muller 1980).
None of the eleven species are known to occur in the project
Area although suitable habitat may exist for some of them.
Wildlife
No animal species listed by USFWS as "endangered or threatened"
breeds in the Project Area or visits it regularly. The peregrine
falcon (Falco pereqrinus) is the only species likely to occur on the
island at all. This worldwide bird probably is a casual migrant and
winter visitor to the island. Migratory and wintering peregrines
usually frequent salt marshes and estuaries, where they can secure
the watertowl and shorebirds that are their main food.
Aguatic
No endangered or threatened aqt~tic species occur in or near
_ tne Project Area.
-
S-9 -
1.3.3 Wetlands
A preliminary wetlands inventory was performed for the Project
Area using aerial photographs and USFS forest inventory maps.
Wetland type vegetation in the Project Area is represented by wet
meadows, low wet sites, and muskeg torest and bog. All these types
occur along Black Bear Creek. Aquatic macrophytes grow in the
vicinity of Black Lake inlet and small drainage channels and ponds
in the wet meadows. These vegetation types are described in
Section 2.2.2.1 of Exhibit w.
Of the inventoried wetlands, those identified as having he
greatest potential for transmission line-related impacts on
waterfowl are mapped on Figures V-S, 6 and 7 of Appendix W-V of
Exhibit W. These principal wetland areas are generally associated
with water bodies and/or have predominantly emergent vegetation.
1.3.4 Estuaries
A small estuary exists at the mouth of Black Bear Creek in Big
Salt Lake. The brackish water habitat consists of a large rocky mud
flat which extends approximately one quarter mile into Big Salt
Lake (ADFG). The estuary is inhabited by euphasid and crangonid
shrim~, sand dabs, starry flounder (Platichthys stellatus) and
sculpin (Cottus Sp).
2. EFFECTS OF THE PROPOSED ACTION ON FISH AND WILDLIFE RESOURCES
2.1 Construction
2.1.1 ~errestrial Species and Habitats
Project construction will remove a maximum of 220 acres of
spruce-hemlock forest from the total available on Prince of Wales
Island. ~his amount is minor compared with the amount being removed
annually by logging. Tnis old-growtn forest is critical winter
habitat for deer in southeast Alaska (ADFG).
Species of birds and mammals inhabiting the Project Area will
move into adjacent habitat, where they will interact with members of
their respective species, causing some emigration, lowered breeding
success and possibly reduced survival. The end result will be a
return of these adjacent areas to about the same population
densities as before the Project was constructed.
Construction of the transmission line will exert somewhat
ditterent effects, in some areas changing a strip of forest habitat
to meadow and brush. The ecotone thus created will favor birds that
utilize both forest and meadow: flycatchers, some owls and hawks,
robin and some sparrows. Where the transmission line crosses muskeg
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the poles and wires will provide new perches for eagles, hawks,
flycatchers and kingfishers.
Transmission lines across wetlands offer special hazards to
waterfowl, especially the larger species (geese and swans). The
transmission line routing has been carefully selected to avoid
flight corridors of waterfowl. James and Haak (1979) found that
birds in tight flocks were most susceptible to collisions and that
the majority of collisions were with the ground wire, which was at
the top of the line assembly. Even in areas rather heavily used by
waterfowl the incidence of collisions with 500-kV lines was low.
There ~ere so many variables that affect the rates of collision and
mortality that extrapolation from one situation to another is
unwise. ~he transmission line for the Black Bear Lake Project will
avoid bird collision problems by 1) avoiding wetland crossings and
edges where waterfowl are abundant, and 2) placing the line at
minimum height. ~he Project is not within any major waterfowl
migration route (Ring 1981).
2.1.2 Aquatic Species and Habitats
Temporary Stream Diversion
Black Bear Lake outflow will be diverted through a cofferdam
and culvert in the streambed at the damsite. This will allow
construction in the dry of the dam and intake structure. The
diversion will not have signiticant impact on fish populations or
habitat either in Black Bear Lake or in the stream. This section of
the stream is not critical fishery habitat.
Black Bear Lake Damsite
Construction Staging Area
Talus material from excavation at the damsite will be placed in
Black Bear Lake to form a temporary construction staging area. This
material, consisting of talus material of the same type which forms
the natural lake bottom, will later be removed and used for fill for
the left dam abutment. Placement and removal of this talus material
will temporarily increase suspended sediments in the immediate
vicinity of the construction area. No significant adverse effect on
total fish habitat or populations in the lake is anticipated,
however. Soil overburden will be stockpiled on land for landscaping
use after construction and will not be placed in the lake.
S-11
The intake for the temporary diversion culvert will be extended
out into the lake to avoid entrainment of sediment from the
construction area. This will avoid discharge of sediments into
Black Bear Creek downstream of Black Bear Lake.
Powerhouse and Tailrace
Construction Staging Area and Access Road
Initial construction activities in the powerhouse area will
temporarily increase sediment loads in Black Bear Creek above Black
Lake. After erosion and runoff control features have been
completed, introduction of sediments into the stream will be minor.
An existing logging road extends to near the outlet of Black
Lake. This road will be extended to the powerhouse site to provide
Project access. To avoid cutting into a naturally unstable slope,
rock fill will be placed along the east shore of Black Lake for
about 200 feet. The fill will eliminate some aquatic plants and
fish habitat.
Upstream of Black Lake, the access road will be constructed
with sufficient drainage culverts to permit water to flow unimpeded
from the valley wall and intermittent streams to the valley floor
and Black Bear Creek.
Transmission Line
The potential for disturbance of aquatic hacitat at
transmission line stream crossings will be reduced to a minimum by
tollowing USFS policies on protection of fisheries habitat during
clearing-type operations (Southeast Alaska Area Guide, USFS 1911).
The number of stream crossings at potentially sensitive ~oints in
streams has been held to a minimum for the proposed route.
2.1.3 Major Ecosystem Alteration
Vegetation
The major construction impact on vegetation will be clearing
for the access to and construction of Project structures. The
overall effect will be a reduction in woodland productivity where
structures replace torest trees, and in revegetated disturbed areas,
the replacement of woodland with early secondary successional plant
S-12
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-cleared will be salvaged and sold. ----..
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Damsite
Construction activities at the damsite will require the clearing and
disposal of four acres of vegetation. This vegetation consists of
subalpine copses (mainly mountain hemlocks) interspersed with
semi-open shrub growths and both wet and dry open areas dominated by
sedges and heath species, respectively. Also, in the area of the
left abutment, salmonberry thicket will be cleared. Since all trees
are of small size, no merchantable trees will be cleared.
Powerstation and Construction Area
Old growth spruce forest will be cleared for construction of
the powerstation and aSSOCiated facilities. Construction of the
steel penstock section from the penstock portal to the powerstation
will require the removal of salmonberry and alder thicket along the
stream as well as a small amount of oldgrowth hemlock forest. The
construction area comprises both sides of the stream between the
powerstation and will require the clearing of oldgrowth spruce
forest as well as salmonberry and alder along and within the stream
channel. Total clearing requirements from the powerhouse to the
portal will be three acres.
The clearing of the powerstation and construction area will
necessitate the removal ot mature timber trees, mainly western
hemlock and Sitka spruce, as well as some mountain hemlock, western
redceaar, and Alaska-cedar.
Access Road
The access road ROW from the end of the existing logging access
road at the outlet of Black Lake to the powerstation will require
the clearing of approximately five acres ot oldgrowth spruce forest
and oldgro~th hemlock, and a small amount of muskeg area and alder
thicket. The placement of till along the short section of Black
Lake will eliminate some aquatic plants.
The clearing of the access road will necessitate the removal of
mature timber trees, mainly western hemlock and Sitka spruce, and
some mountain hemlock, western redcedar, and Alaska-cedar.
S-13
Transmission line
The transmission line will be routed along the access road
between the powerstation/switchyard and the Black Lake outlet. This
section of the route will not require any significant removal of
trees beyond what was removed tor the access road ROW. The
remainder of the route will, for most of its length, parallel road
ROWs. Extensive clearing ot trees in most of these areas will also
be avoided, since much of the area has been or will have been
logged.
Wildlife
Only minor wildlife population reductions are anticipated as a
result of the project (ADFG).
Aquatic
Alterations of existing aquatic ~cosystems during the
construction phase will occur during reservoir tilling. Existing
rainbow trout spawning areas in Black Bear Lake will be inundated
and will probably no longer be SUitable. It is unlikely that new
spawning areas will become available unless reservoir fluctuations
are controlled during the spring spawning season. During reservoir
filling, flows will be greatly reduced in the existing stream bed
between the dam and powerhouse and will be nearly eliminated just
below the dam. However, thiS reach ot the stream is not critical
fishery hatitat.
stream flows downstream of the powerhouse will also be affected
during filling of the reservoir. The most pronounced effect will
occur between the powerhouse and the major southwest tributary above
Black Lake (see section 3.2.2.2 of Exhibit W). Below the confluence
of this tributary, Black Bear Creek flows would be much closer to
natural conditions during reservoir filling. To fill the reservoir
from E1. 1680 (present lake level) to El. 1115 (normal maximum pool
elevation) will require 8,000 acre-teet, or about 228 acre-teet for
each 1 ft. rise in reservoir elevation. If the reservoir were
filled during a short period upon completion of construction,
maintenance of adequate downstream flows would be very difficult.
Therefore, it is proposed that reservoir filling begin during the
final construction phase and continue through the first three years
of Project operation. The following table summarizes the proposed
minimum releases for downstream tlow maintenance during reservoir
, •
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filling. Minimum downstream releases are generally the
those proposed for Project operation in 1986, and
considerations were used as tor tne analysis of operation
described later in this document.
RESERVOIR FILLING AND MINIMUM RELEASE
Total Water Min. Downstream
Month Available (cfs) 1/ Felease (cfs)
Jan 6.5 6.5
Feb 5.4 5.4
Mar 4.1 4.1
Apr 15.8 1.0
May 39.0 11.0
June 41.1 34.0
July 21.4 21.4
Aug 22.9 22.0
Sep 36.6 34.0
Oct 47.1 34.0
Nov 34.0 25.0
Dec 24.8 10.0
same as
the same
flows as
1/ Mean of average monthly flows for 30 yr of synthesized data •
ADFG has requested that the April m1n~mum release be increased
trom 1.0 cfs to 15.8 cfs to assure adequate flows for pink and chum
salmon fry outmigration. ADFG suggests that the water lost for
reservoir filling during April could be recouped by reductions in
the minimum flows of the preceding table tor the months June through
November. While increasing the April minimum flow may benefit
pink/chum outmigration, reductions in the minima for the other
months may increase the potential for adverse impact on the fishery
resource upstream of Black Lake during reservoir filling. The
8-15
continuing studies discussed elsewhere in this document will provide
more detailed information on fish habitat and use in this reach,
which will allow refinement of the proposed reservoir filling
release regime.
Endangered or Threatened Species
Plants
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No endangered or threatened plant species are known to occur •
in the project Area.
Wildlife
The only endangered species that might occur in the area, the
peregrine falcon, is too uncommon a visitor to be directly affected
by the Project. peregrines may use the transmission line poles for
perching, but the spacing of wires will be such that chances of
birds being electrocuted will be minimized.
Aquatic
No threatened or endangered aquatic species are known to occur
in the Project Area.
2.2 Cperation and Maintenance
2.2.1 'Terrestrial Species and Habitats
Operation of the project will cause no significant changes in
~ildlife habitat beyond those introduced by project construction.
Revegetation of the construction work areas will result in gradual
habitat recovery for songbirds and small mammals. Most of the
larger birds and mammals ~ill continue to avoid the main part of the
project, but with noise at lo~r levels, will reoccupy peripheral
habitat.
Beaver dams under Project conditions will receive more frequent
but less extreme high flows than at present. If a beaver dam is
maintained in the usual manner, the likelihood that it will breach
is reduced.
S-16
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Maintenance of the transmission line ROW will sustain a
relatively uniform strip ot open habitat as long as the Project is
in operation. Broadleafed shrubs will be suppressed by manual means
where necessary. ADFG has recommended against the use of
herbicides.
Management of the transmission line ROW tor low vegetation will
aid grouse and edge-dependent birds (flycatchers, waxwings, some
warblers) by providing berry-and seed-bearing plants. The poles
and wires ~ill be used tor resting and perch-hunting by some birds.
Transmission poles will provide potentially attractive nest sites
for some large birds such as the red-tailed hawk. With adequate
wire spacing to prevent electrocutions this is not likely to cause
bird mortality. ~here is danger of the nest sticks shorting across
wires however and nesting must be prevented. Methods available and
tested include altering poles and crossties to render them
inhospitable and erecting a separate nest platform near the pole
selected by birds.
2.2.2 ~uatic Species and Habitats
Black Bear Lake
Reservoir Level Fluctuation
Normal maximum daily reservoir fluctuation will be
approximately one foot. During the spawning period of Black Bear
Lake rainbow trout, such fluctuations could cause the loss of eggs
deposited in very shallow areas. Eggs deposited in slightly deeper
water would be unaffected.
Seasonal reservoir level tluctuations are summarized in Tables
W-9 and w-l0 and on Figures W-3 and W-q of Exhibit W. The reservoir
level increases a few feet from April to June, then decreases from
June to August. This could result in tne loss by desiccation of
rainbow trout eggs (or alevins) deposited in very shallow water
areas during the period of highest reservoir level. Eggs and
alevins in somewhat deeper water would not be affected.
Year-to-year fluctuations in reservoir levels might also affect
rainbow trout spawning, depending on the amount of suitable spawning
habitat available each year under different water level conditions.
S-17
Fish Entrainment
Each flared intake port will be approximately 7 ft. by 7 ft.,
for a cross sectional area of about 49 sq. ft. The maximum
discharge capacity of the Project will be approximately 64 cfs, so
that the maximum approach velocity at each intake opening will be
about 1.31 ft/s, with lower velocity at the trashrack. At lower
Project discharges, water velocities at the intake and trashrack
will be correspondingly lower.
Bell (1973) has reported the following swimming s~eeds for
average-sized to large adult rainbow trout:
Crusisin~eed
(ft/s)
4.5
sustained speed
(ft/s)
13.5
where cruising speed is defined as that maintainable for long
periods (hours) and sustained speed that maintainable for a period
of minutes. Smaller rainbow trout have lower swimming speeds.
Most adult rainbow trout should be able to avoid entrainment
into the power intake rather easily. Smaller adults and juveniles
may be entrained at higher Project discharges, however. Any fish
entrained would pass through the Project water-~·conductors and
turbines and would probably be killed. Although the mortality rate
ot fish entrained would approach 100 percent, entrainment is not
expected to have significant impact on the Black Bear Lake trout
population, since only a small percentage of the total number of
fish would be subject to entrainment.
Downstream of Black Bear. Lake
Water Temperature
water temperature, in addition to affecting the timing of
stream entrance and spawning by adult fish, determines the rate of
development from egg through alevin to tree-swimming fry. The rate
of this development can be critical to the survival of juvenile
fish.
water temperatures in tbe stream below Black Bear Lake are in
part determined by temperature of lake outflows. This effect is
most important tor the reach of Black Bear Creek upstream of Black
Lake, and becomes less so the further downstream one ~roceeds.
S-18
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Thermograph records of water temperatures at four stream
locations are given in Appendix W-B of Exhibit w.
Black Bear Lake is strongly thermally stratified in August,
less so in September, and has uniform temperature by late october.
The lake's thermocline descends from a depth of 30 to 40 feet in
August to a depth of 50 to 10 feet in late September. During the
winter, an inverse thermal stratification would be expected, with a
layer of water colder than 4 degrees C at shallow depths below the
ice.
In order to minimize changes in the natural downstream water
temperature regime with the Project, the three-port power intake is
designed to withdraw water from as near the surface of the reservoir
as possible as much of the time as possible. This will result in
withdrawal of warmer water from above the thermocline during
summer months and the coldest possible water from near the reservoir
surface in the winter. DeSign drawings of the proposed power intake
are shown in Appendix S-B. The estimated cost of the three-port
intake is $365,000 . (January 1981 price level, excluding engineering
and contingency) •
In toth January and August, water would be withdrawn from
depths of 12 -20 feet about 80 percent of the time, and from
depths of 20 -22 feet the rest of the time (20 percent). These
results are based on analysis of the reservoir levels which will
occur with downstream environmental flow constraints.
Since withdrawals during the summer and fall will be from above
Black Bear Lake thermocline, stream water temperatures downstream of
the powerhouse will change little, if at all, from existing
conditions during this time ot year under normal flow conditions.
Fish activity during this period, including salmonid migration into
Black Bear Creek and spawning, should not be adversely affected.
Stream winter water temperatures will be increased somewhat by the
Project, perhaps by as much as 1.5 - 2 degrees C in the stream reach
upstream ot Black Lake under extreme low flow conditions, which can
occ,ur in January and February. 'Ihe increase would be smaller under
more normal flow conditions. The magnitude of winter water
temperature increase with the Project would become progressively
smaller as one proceeds downstream.
Pink and chum salmon juveniles do not remain for long in fresh
water, but either swim or are carried downstream to brackish or salt
water upon reaching the free-swimming fry stage atter emergence from
streambed gravels. If warmer than normal winter water temFeratures
have accelerated the intragravel stages of development, this
downstream movement may occur betore sufficient numbers of food
organisms are available in the marine coastal feeding areas, and the
8-19
young fish may suffer high mortality from starvation. Differences
from natural stream temperatures of as little as 2 or 3 degrees F
during the egg-alevin development period can result in significant
losses (Meehan 1974). Pink and chum salmon spawn both up-and
downstream of Black Lake. The part of the stream below Black Lake,
where the principal pink and chum spawning/incubation areas are
located, would be the least susceptible to any Project-caused winter
temperature increases. Under winter extreme low flow conditions,
intragravel development of pink and chum in the stream above Black
Lake may be accelerated sufficiently to cause early outmigration.
Under more usual (higher) winter flow conditions, hOWEver, pink and
chum intragravel development will probably not be significantly
affected.
Sockeye and coho salmon incubation and rearing areas occur both
up-and downstream of Black Lake, with the principal sockeye area
being in and above Black Lake. Sockeye and coho salmon fry
generally remain in fresh water after emergence from the streambed
gravels, rearing in suitable areas of the stream or associated lakes
and feeding on plankton and insects (Scott and Crossman 1973). If
warmer winter water temperatures accelerate the rate of development
of invertebrates and plankton in Black Bear Creek and Black Lake as
well as that of sockeye and coho in the gravels, early emergence of
sockeye and coho probably would not be as potentially serious as it
would be for pink and chum. In any event, since the Project will
elevate winter water temperatures more upstream of Black Lake than
it will downstream, the potential for adverse impact on coho and
sockeye will be greater for the incubation areas above Black Lake
than for those downstream.
Other salmonids inhabiting the stream include Dolly Varden
(fall spawning), steelhead-rainbow trout (spring spawning), and
cutthroat trout (spring spawning). Rainbow and cutthroat spawning
and incutation will not be affected temperature-wise, since the
project will have little, if any, effect on spring and summer
natural water temperature regimes. Dolly Varden spawning in the
fall will not be affected, but winter incubation and emergence could
be accelerated above Black Lake, as discussed above for salrron.
ADFG considers the Black Bear Creek system as
"temperature-sensitive", meaning that under natural summer low-flow
conditions, water temperatures can become high enough to adversely
affect fish and other stream organisms. ~emperature-sensitive
streams in Southeast Alaska typically are lake system streams, are
oriented north-south, and have slow moving, organically-stained dark
water (Kelly 1979, 1980). The Project may have a beneficial effect
on water temperatures during summer low flow periods, since as
explained later in this section, flows with the Project will be
higher than natural flows for a significant part of the day during
summer months and higher flows can reduce water temperatures.
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Discharge Regime
From 1986 to 1991, flows in the falls and cascades reach of the
stream between the dam and powerhouse would be eliminated except for
local inflow and Project spills during flood events. After 1991
there will be essentially no spilling and therefore no flow in the
natural streambed between the dam and powerhouse except for local
inflow. This reach of the stream is not critical fishery habitat.
Modification of the natural stream discharge regime downstream
of the powerhouse by the proposed Project could affect fish habitat,
migration, and development of eggs and juveniles. The further
downstream one proceeds from the Project tailrace, the smaller these
flow modifications as a percent of total flow will ce, since a
progressively greater percentage of stream flow derives from
unregulated runoff as one moves downstream, as illustrated on
Figure W-5 of Exhibit Wand in the following tatle:
DRAINAGE AREAS AND PROJECT REGULATION
Percent of Cumulative Drainage Area
Location Regulated Unregulated
project tailrace (I) 100 0
Upstream ot major upper
casin tritutary (II) 58.7 41.3
Downstream of major upper
basin tritutary (III) 34.5 65.5
Black Lake inlet (IV) 28.9 71. 1
Black Lake outlet (V) 24.6 75.4
Mouth of stream (VI) 10.4 89.b
Early in Project planning, a discharge regime to follow system
load demand was developed. This regime would cause daily flow
tluctuations which are large compared to minimum releases for the
reach of the stream above Black Lake, and would greatly modify
natural seasonal discharge patterns in the upper reaches of the
stream. Such a regime would almost certainly have significant
adverse effect on fish spawning and egg and intragravel larval fish
survival upstream of Black Lake. Therefore, in order to reduce the
potential for significant adverse impact, the release regime was
modified by decreasing daily maximum discharge and/or increasing
5-21
daily m~n~mum discharge during those months identified as important
for salmon spawning (July through November) and incubation (December
through May). The result is a discharge regime which would have
smaller daily fluctuations and would more closely follow seasonal
changes in natural discharge than would be the case for the original
regime. The modifications analysis was performed for two cases:
1) 1986, when Project generation capacity would not yet be fully
absorbed and Project discharges would therefore include spills from
the Deservoir, and 2) 1991, when essentially no spilling would
occur. This analysis is presented in Figures W-6 through W-17 of
Exhibit w.
For 1986, the proposed modified flow regime gives higher winter
flows (January-March), lower May flows, higher summer flows
(July-September), lower October flOWS, and lower Decemter flows
compazed to existing conditions. April, June, and November flows
would be essentially unchanged. The range of daily fluctuations
will fall ~ithin the range of natural fluctuations except during the
period January-March. The magnitude of daily fluctuations will
probably be approximately equal to or less than that under natural
conditions except in January-March and perhaps June and July, but
fluctuations will be more frequent on a daily basis with the Project
than under existing conditions.
For 1991, the proposed modified flow regime gives higher winter
flows (January-March), lower late spring flows (May-June), higher
summer flows (July-August), and lower October and December flow
compared to existing conditions. April, September, and November
flows would be essentially unchanged. The range of daily
fluctuations will fall within the range of natural fluctuations
except during the period January-March. The magnitude of daily
fluctuations will probably be apprOXimately equal to or less than
that under natural conditions except in January-March and perhaps
June and July, but fluctuations will be more frequent on a daily
basis with the Project than under existing conditions.
In summary, the prinCipal flow regime changes downstream of the
powerhouse tor both 198b and 1991 will be higher winter and summer
flOWS, less frequent flood and low flow events, and more frequent
flow fluctuations on a daily basis. Higher winter flows may
increase survival of salmonid eggs and alevins by decreasing the
frequency of ice formation in the incubating gravels, especially
upstream of Black Lake. Higher summer flows may decrease the
frequency of occurrence of high water temperatures which almost
certainly occur during dry summers under natural conditions. This
would tend to increase survival ot rearing salmonids, but higher
water velocities aSSOCiated with the higher summer flows may reduce
rearing habitat in certain reaches of the stream. Effects of
reduction of frequency of high and low flow events are discussed in
Appendix W-B of Exhibit W. Increasing flow fluctuations on a daily
basis will probably not Significantly affect fish populations or
habitat downstream of Black Lake.
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Daily fluctuations in the stream reach above Black Lake
ordinarily would have the potential to cause significant adverse
effect. However, the reach of the stream above the principal
spawning and rearing areas in the upper watershed is braided and
carries surface flow only intermittently. A major porticn of the
surface flow in the principal spawning/rearing reach of the stream
above Black Lake is derived from groundwater flow supplied
principally by the outflow from Black Bear Lake, which becomes
entirely subterranean flow in the vicinity of the proposed
powerhouse under low flow conditions. Maintenance of this
subsurface flow will greatly reduce the downstream effects of daily
fluctuations in flow releases from the powerhouse.
After more detailed information on fish habitat and use becomes
available through the continuing studies discussed elsewhere in this
document, the modified flow regime described above may require
refinement in order to assure that downstream fisheries impacts are
reduced to a minimum.
The ATC wood waste fired generation project might come on line
in 1981 or 1982 and would provide two to four MW for 15 years. It
might be possible. to use the ATe project for peaking power in the
system so that the Black Bear Lake Project could be operated more
frequently on a baseload mode during that period. The proposed
Project could also be shifted to operation principally for baseload
power after about 1992, when Project generating capacity is fully
absorbed by power system demand. Baseload operation would allow
greater flexibility in the discharge regime of the proposed Project
so that discharges could be made to follow natural patterns more
closely. Daily flow fluctuations and rate of change would also be
less with baseload operation than under a peaking mode. Such
modifications in the Project discharge regime would further reduce
the potential for downstream fisheries impacts •
Dissolved oxygen and Nitrogen
The Project power intake will withdraw water from no deeper
than 22 feet below the reservoir surface, so that no oxygen-poor
water will be discharged from the powerhouse at any time during
the year.
The multilevel intake is designed and will be operated so that
no air is entrained through vortex action under normal operating
conditions. The Project thus will not increase dissolved nitrogen
concentrations downstream of the powerhouse •
5-23
2.2.3 Major Ecosystem Alteration
Vegetation
Reservoir OEerations
The amount of vegetation biomass on the slopes abutting Black
Bear Lake is not sufficient to cause water quality problems if not
cleared before dam closure. Nevertheless, in order to avoid
unsightly dead snags and potential debris problems at the intake and
spillway, vegetation between EI. 1680 (present lake level) and
EI. 1710 will be cleared betore the reservoir is filled. Vegetation
between EI. 1710 and 1715 (maximum normal operating pool) will not
be cleared, since most vegetation in this zone will· su~vive as
indicated in the following discussion.
The present lake level is EI. 1b80 and the normal maximum
reservoir level will be EI. 1715. In general the vegetation in this
zone consists of hemlock and hemlock-spruce forest stands,
salmonbe~ry and alder thickets, mountain hemlock scrub stand, rock
field subalpine meadow, and subalpine hemlock copses intermixed with
open areas.
Black Bear Lake will not be maintained at a constant pool level
but will fluctuate over time. The eftects on vegetation of periodic
pool level fluctuations would be most severe if the inundation
occurs during the growing season (June to September). Most trees
and shrubs are able to survive prolonged inundation during their
dormant season but species' response to inundation during the
growing season is variable. Flood frequency, duration, and depth
are the major factors determining a species' response to inundation
during the growing season. During the growing season the highest
pool levels will be reached in average and wet years. During
dry years, highest pool levels will be reached in the fall and early
winter. The following table, based on proposed Black Bear Lake
pool operation levels with downstream environmental constraints,
gives the percent exceedance of reservoir levels during the growing
season.
S-24
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PERCENT EXCEEDANCE OF POOL LEVELS
DURING THE GROWING SEASON (JUNE TO SEPTEMBER)
No. of Years of
Range of Pool Average Percent OCcurrence Out of
Level Fluctuations Level Exceedance 30 Years
1680 1680 (present level)
1b85-1b92 1b88 100 30
1689-1696 1692 95 28
1b91-1b98 1b94 90 27
1694-1699 1697 80 24
1b99-1705 1702 70 21
1703-1708 1705 60 18
1703-1712 1707 50 15
1708-1714 1711 40 12
1710-1715 1712 30 9
1712-1715 1713 20 6
1713-1715 1714 10 3
1715 1715 5 1
The vegetation presently between EI. lb80 and approximately
EI. 1688 would be permanently inundated and lost (see above table).
There would be a gradation ot vegetation damage between EI. 1688 and
EI. 1715 with the most severe damage occurring at the lower
elevations.
The zone ~etween EI. 1b88 and EI. 1707 would ~e severely
stressed. Allor a portion of this zone will be inundated during
the growing season tor at least 50 percent of the time (see above
table). Nearly allot the woody vegetation in the areas to be
inundated 90 to 70 percent of the time would, in all prorability,
die within three to five years. Herbaceous vegetation ~ould be
eliminated within two to three years. In the area to be inundated
from 60 to 50 percent of the time, only the most flood tolerant
tnees and shrubs would survive, probably at a reduced gro~th rate.
Herbaceous vegetation would be sparse and probably be represented by
annuals and flood tolerant grasses and sedges.
Unfortunately, very little is known concerning the flood
tolerance ot plants common to the Black Bear Lake shoreline.
wal ters et ale (1980) classity the flood tolerance ot red alder and
Sitka alder as very tolerant (withstand flooding for periods of two
or more growing seasons); Sitka spruce, western redcedar, and
western hemlock as tolerant (withstand flooding for most of one
growing season); and Alaska-cedar as intermediately tolerant (able
to survive flooding for one to three months during the growing
season). Minore and Smith (1971), based on flood tolerance studies,
ranks red alder, Sitka spruce, and western hemlock as intermediately
S-25
tolerant. In a review ot the literature, Whitlow and Harris (1979)
rank western redcedar as tolerant (able to survive flooding for one
growing season, with significant mortality occurring if flooding is
repeated the following years) and Sitka spruce and western hemlock
as slightly tolerant (able to survive flooding or saturated soils
for 30 consecutive days during the growing season). It is assumed
that inundation for all or a significant portion of two or more
consecutive growing seasons would kill most of the woody vegetation
between EI. 1b88 and EI. 1707. An increase in alders could occur at
the less frequently inundated upper elevations.
The zone from EI. 1707 to EI. 1715 will be inundated less
frequently (see above table) and vegetational changes would be less
severe than for the zone just described. The vegetation between
EI. 1707 and EI. 1712 would be sparse with only flood tolerant
shrubs able to survive. Between EI. 1712 and EI. 1715, the maximum
level, most of the original woody vegetation would remain, provided
that flooding does not occur for two or more consecutive growing
seasons. However, even if this does occur, sufficient time could be
expected between subsequent high tlooding events that the vegetation
would have time to recover. One flooding event of one week or more
would be sufficient to kill most of the herbaceous vegetation.
Causes would be anaerobic soil conditions, mechanical damage from
floating debris, and siltation from receding water covering growing
tips.
~inter pool levels above EI. 1b88 should not, by themselves,
significantly affect the dormant vegetation. However, they may
exacerbate the stress on vegetation already impacted from inundation
during the preceding growing season.
Water table levels will rise in direct response to the rise in
reservoir water levels. However, since most of the shoreline is
steep, the rise in water table level will not be greater than the
reservoir surface level. This may cause some localized wetter than
normal conditions on slope areas immediately above the reservoir
water level. In these wet areas, quite common at present, sedges
may zeplace trees and shrubs. According to studies by Minore and
Smith (1971) on the effect of raised winter water table depths on
plant growth, red alder, western redcedar and Sitka spruce ~ill grow
where the winter water table is less than 15 cm deep. Red alder and
western redcedar are able to grow with the water being stagnant
while Sitka spruce requires a flowing water table. Western hemlock
is intolerant of water tables less than 15 cm deep. It would
appear, therefore, that any raised water tables along the shoreline
would result in the death ot western hemlock and, in all
probability, mountain hemlock. Sitka spruce and alder, however, may
survive raised water tables immediately above the new shoreline.
S-26
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Downstream Flows
Project downstream releases are not expected to cause any
significant alterations of the vegetation along the Black Bear Creek
stream corridor. The reasons are 1) the total annual streamflow and
its monthly distribution will remain the same, 2) the regulated area
of the watershed is small, approximately ten percent, compared to
the total drainage area, and 3) a major source of water maintaining
the streamside wet areas appears to be surface and subsurface flows
from adjacent slopes. Nevertheless, overbank flooding may also be
important for maintaining the vegetation in these poorly drained
areas. Project releases will, however, be well within the range of
natural fluctuations. The overall effect of the Project will be a
reduction in the frequency and magnitude of flood flows and a
decrease in trequency and increase in magnitude of low flows. This
influence of the regulated flow on the natural flow from the
unregulated drainage area will decrease progressively downstream.
The large natural fluctuations will still occur downstream,
particularly downstream of Black Lake.
The most pronounced effects on downstream flows from Project
releases will occur. between locations I and II (see table on
page S-21). The upper reaches of this stream section are bordered
by bands of alders and salmonberry as well as canopy-sized hemlock
and spruce trees. The lower halt of the section contains braided
subchannels and alluvial fans of tributaries. Vegetation is mostly
canopy-sized hemlock and spruce with scattered alders. ~hese trees
are not dependent on stream flows for their survival or
maintenance. ~he Project effects of reducing high flows and
increasing low flows should not have any appreciable effect on this
vegetation. There may, however, be a change in the groundcover
flora or an increase in shrubs.
A muskeg forest and meadow occurs along Black Bear Creek
between locations III and IV (see table on page S-21). Less than
one-third of the water passing through these wet areas will be
regulated flow from Black Bear Lake. The major Project effect will
be a reduction (by less than one-third) in overbank flooding. If
overbank flooding from large storm events is important in
maintaining the muskeg area, then the project may cause some
vegetational changes there. The reduction in flooding could be
sufficient to cause a shift from hydric to more mesic conditions.
In the extreme case, the open muskeg area could become colonized by
additional shrubs, and eventually develop into semi-open
successional woodland stages dominated in turn by alder, Sitka
spruce, and western hemlock. However, it does not seem likely that
any changes would go beyond an increase in shrubs and small trees •
Project releases would
water levels. ~herefore, no
either along the shoreline
contain aquatic macrophytes.
not cause any changes in Black Lake
vegetational changes are expected
or in those few shoreline areas which
5-27
Downstream of Black lake, Project releases are expected to have
only minimal, if any, eftect on the vegetation. In this area of
poor drainage and a naturally high water table, much of the water
maintaining tne vegetation in tne wet meadows and wet low sites is
surface and subsurface drainage from the adjacent slopes as well as
unregulated streamflow (specifically, overbank flooding). Large
natural streamflow tluctuations and drainage from adjacent slopes
will be unaffected. Their contribution to maintaining the present
wetland type vegetation will remain unchanged by the Project. The
Project-regulated flow will be such a small component of the total
water flow through this area that its effects on vegetation will be
insignificant.
Wildlife
Reservoir surface fluctuation will not significantly affect
wildlife use of the lake, since such use at present is primarily for
drinking. Most of the strongly water-oriented mammals and birds of
the area occur downstream of the proposed reservoir.
~he maintenance of the transmission line in a perpetually
low-growth condition will provide a stable edge-oriented tird and
mammal community, with the tood-chain relationships those of forest
species feeding in the open. ~his will be a linear interruption in
the otherwise continuous coniferous torest ecosystem.
Aquatic
Reservoir Level Fluctuation
Normal maximum daily reservoir fluctuation will te about
one toot. Seasonal fluctuations are summarized in Tables W-9 and W-
10 and on Figures W-3 and W-q of Exhibit W. These fluctuations
could affect rainbow trout spawning in Black Bear Lake.
Stream Water Temperature
Summer and fall water temperatures downstream of the powerhouse
will change little, if at all, with the Project, except as noted
telow.
Winter water temperatures will be increased by as much as
1.5-2.0 degrees C in the stream above Black Lake under extreme low
flow conditions, which can occur in January and February. The
increase would be smaller under more normal winter flow conditions.
S-28
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The magnitude of winter water temperature increase would become
progressively smaller as one proceeds downstream.
The Project may have a beneficial effect on stream water
temperatures during summer low flow periods, since with-Project
floliois will be higher than natural flows during summer and higher
flows would reduce water temperatures. Effects of these temperature
modifications on stream fishery resources were discussed above.
Discharge Regime
Flows between the
except for local inflow,
critical fishery habitat.
dam
but
and
this
powerhouse
reach of
would be eliminated,
the stream is not
Downstream of the powerhouse, the principal tlow regime changes
will be higher winter and summer flows, less frequent flood and low
flow events, and more frequent tlow fluctuations on a daily basis.
Effects on fishery resources in different reaches of the stream were
discussed above.
2.2.4 Endangered or Threatened Species
Plants
No endangered or threatened plant species are expected to be
affected by Project operations, since none are known to occur in the
Project Area.
Wildlife
Project operation will not affect any endangered, threatened,
or candidate species. Should a peregrine falcon visit the Project
Area or the transmission line (a remote possibility), the bird would
encounter no hazard.
5-29
Aquatic
No threatened or endangered aquatic species are known to occur
in the project Area.
2.2.5 Cumulative Impacts
othe~ Hydroelectric Projects
There are no other existing or proposed hydroelectric projects
in the Black Bear Creek basin.
Cumulative Effects of !he proposed Project
and Logging Operations on the Aguatic Ecosystem
Stream suspended sediment loads will be temporarily increased
by the project only during initial and final construction phases,
and then probably only above Black Lake. No cumulative effects with
logging are expected, since timber is being harvested only
downstream of Black Lake.
Higher summer flows with the Project may reduce summer water
temperature increases that might occur due to logging in the lower
baSin. Higher winter flows with the Project would tend to
ameliorate lowering of winter minimum water temperatures that might
take place as a result of streamside vegetation removal during
timber harvest in the lower basin.
Stream flows in the lower basin will probably increase for the
first few years after logging operations, but as mentioned above,
such changes are usually less than climate-caused variations.
Cumulative effects of the proposed Project and logging operations on
stream flow in tne lower basin theretore would generally be expected
to fall within the range of conditions presented in the analysis in
Section 2.2.2, except that minimum flows for the cumulative case may
be slightly higher than for the with-Project analysis.
5-30
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Other Cumulative Effects with Logging Operations
'Ihe total amount of wildlife habitat that will ce removed or
disturbed by the proposed project, including the transmission line
ROW, is at most one-third the area presently being logged in the
lower Black Bear Creek valley alone.
2.3 Termination and Abandonment
2.3.1 'Ierrestrial Ecosystems
vegetation
Black Bear Lake
Removal of the dam would cause the lake level to return to
El. 1680. This would expose the unvegetated inundated zone ranging
from El. 1680 to El. 1115. The higher elevations would contain a
sparse cover of flood tolerant shrubs and herbaceous vegetation.
primary succession would begin in the bare areas. The time lag
between exposure of the area and the establishment of vegetation
would vary, as would the species composition of the pioneers,
depending on the nature of the surface exposed, the availatle seed
source, and other factors. Along most of the exposed shoreline of
Black Bear Lake, mosses and perennial herbs probably would become
established in the available soil. Small shrubs such as salmonberry
and Devilsclub, followed by alder and hemlock, would eventually
colonize the area. In the vicinity ot the rock field at the
southeastern end of the lake, the colonizing vegetation would be
similar to that presently existing.
Other Areas
If project structures such as the powerstation and associated
fac~lities and roads were removed, the areas would have to be
regraded to limit erosion. The disturbed soil would be naturally
colonized by dense alder growths. Regeneration ot vegetation would
be similar to that in slide areas, former logging roads and highly
degraded logged areas. Eventually (50 years or more), spruce would
begin to replace the alders. However, to ensure that a more
desirable vegetation cover is established as rapidly as possible in
these areas, it would be necessary to artificially reforest the
regraded areas. Decisions concerning the need for any reforestation
program would have to be made at the appropriate time •
S-31
Wildlife
Following the removal of Project facilities and cessation of
maintenance activities tor roads, trails and the transmission line
ROW natural succession will result in gradual restoration of the
pre-Project vegetation communities and the animal and bird
populations supported by them. Bird populations will respond in
much the same manner as they do to clearcutting (Kessler 1979).
Mammals will use the Project clearings, as they do other clearings,
for feeding or movements.
2.3.2 Aquatic Ecosystems
Black Bear Lake
Breaching or removal of the dam would return the lake to its
preimpoundment level. Original rainbow trout spawning areas would
again become available.
Downstream
Streamflow regime would return to pre-Project conditions, as
would stream temperatures. The modified channel reach in the
vicinity of the powerhouse would probably not return to natural
conditions. Fishery productivity ot Black Bear Creek would probably
return to pre-Project levels. Breaching the dam would probably
cause a temporary increase in suspended sediments in the creek
downstream of the Project site.
S-32
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3. MEASURES TO ENHANCE THE ENVIRONMENT OR TO AVOID OR MITIGATE
ADVERSE ENVIRONMENTAL EFFECTS
3.1 Preventive Measures and Monitorinq (Protection)
3. 1. 1 Monitoring
ProFosed monitoring programs are described in the following
sections. The ongoing and proposed aquatic, vegetaticn, and
wildlife monitoring programs are based on recommendations from
Applicant·s consultants and from state and federal agencies (see
correspondence in Appendix W-D of Exhibit W). These monitoring
programs are designed to provide additional detailed information
which may be required to further refine proposed Project oFerations
to insure that adverse impacts are avoided or reduced to a minimum.
It is Applicant's considered opinion that no changes will be
required in deSign or location of Project civil works as described
in this license Application.
3.1.1.1 Project Operation MQnitoring
Supervisory control equipment will be provided to permit remote
control indication and communication of powerhouse generating data,
reservoir level, and multilevel intake monitoring data to a remote
central control room at Klawock.
3.1.1.2 Aquatic
Fisheries and Hydro!ogical/Limnoloqical Studies
Applicant·s 1981-1982 ecological field investigations, dealing
primarily with the aquatic ecosystem and fisheries but also
including mammal populations upstream of Black lake, began in
July 1981 and will continue through mid-1982. The interim report is
attached to this License Application under Appendix W-B of
Exhibit W. The Commission will be provided with copies of the final
report uFon completion of the study •
S-33
Construction Phase
Water Quality Monitoring
It is proposed that dissolved oxygen, turbidity, and oils and
grease be monitored frequently during construction at a suitable
site in Black Bear Creek between the powerhouse construction area
and the confluence of the major southwest tributary above Black
Lake. ~his monitoring will serve a quality control tuncticn during
construction to insure that runoff control measures and procedures
are functioning as intended.
Dissolved Nitrogen Test
The proposed intake structure is designed and will be operated
to avoid air entrainment which could cause elevation of downstream
dissolved nitrogen. levels. Nevertheless, it is proposed that a
one-time test be conducted of the potential for increased dissolved
nitrogen with intentional vortex entrainment of air. Such a test
will permit determination of the potential severity of such an event
and allow formulation of precautions which could be taken in Project
operations to preclude its occurrence. The test would be conducted
once the Project is operational. but at a time ot year when any
increase in nitrogen concentrations will not be detrimental to
downstream fishery resources. Timing will be established in
consultation with ADFG and other appropriate agencies. The test
protocol will include measurement of dissolved nitrogen in Black
Bear Lake and in Black Bear Creek downstream of the powerhouse
discharge both with and without vortex entrainment of air at the
intake.
Post-Project Monitoring
Monitoring of salmon escapement or juvenile outmigration as
appropriate, strea~ temperature. and discharge will be continued
upstream of Black Lake after tne Project begins o~eration.
Frequency of data collection and duration of these continuing
studies will be discussed with state and federal fisheries agencies
at a later date.
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3.1.1.3 Vegetation
A single ground survey of the proposed transmission line
corridor will be conducted during the tinal design stage to verify
the preliminary wetlands inventory. This information will be used
along with the guidelines in Appendix W-V of Exhibit W to establish
the final alignment of the transmission line •
Areas disturbed by construction activities will be regraded and
planted in appropriate natural vegetation. Specific vegetation
requirements such as suitable plant species, soil treatment, seedbed
preparation, seeding rates or seedling densities, and follow-up
maintenance procedures will be formulated after discussions with
USFS. The revegetated areas will be periodically monitored to
identify any problems that may arise, such as eroded areas and poor
plant growth. Appropriate measures will be taken to correct such
problems as soon as possible.
After vegetation is cleared from the reservoir area and the
reservoir is filled, the shoreline vegetation and that in the zone
of fluctuating pool levels will be monitored for any debris control
or erosion problems and unsightly snags. Debris and snags will be
removed, and any ero·sion problems dealt with by appropriate means.
3.1.1.4 Wildlife
Before final alignment of the transmission line within the
proposed transmission corridor is determined during final design of
the project, additional eagle surveys will be conducted as necessary
to complement USFWS data. USFWs'pertormed some eagle survey work in
the vicinity of the Project in 1910, and resurveyed likely eagle use
areas along the proposed Project transmission corridor in
September 1981. The final alignment of the transmission line will
comply with USFWS Eagle Protection Guidelines.
The Project maintenance staff will be briefed by local game
personnel on the handling of wildlife problems (e.g., bear
encounters) on Project lands. Transmission line maintenance and
surveillance personnel ~ill be alerted to potential wildlife
problems, including electrocutions of large birds, which they will
be required to report.
A pre-construction reconnaissance inventory of beaver and other
species using existing beaver impoundments upstream of Black Lake is
underway. USFS and ADFG biologists will be asked to assist the
project maintenance staff in monitoring the possible effects of flow
changes on beavers in Black Bear Creek.
S-35
3.1.2 Preventive Measures
Measures which were
avoid or reduce adverse
following subsections.
included in Project planning in order to
Project effects are discussed in the
3.1.2.1 Minimization of Problems Due to Malfunctions and Accidents
The intake structure and automatic controls will be inspected
regularly to minimize the chance of breakdown.
3.1.2.2 Protection of Services and Environmental Values Ouring
Maintenance and Breakdowns---
The automatic alarm system will signal any failure of intake
structure controls. 'Ihis will allow immediate dispatch of
maintenance crews and prompt return of the intake to normal
operation.
3.1.2.3 Protection ot Fish and Wildlife Resources
Transmission Line
Corridor Selection
Fish and wildlife values were fully considered in evaluation of
alternative transmission line corridors and selection of the
proposed corridor. This analysis is discussed in detail in
Section 8.4.1.6 of Exhibit w.
Construction
'I'he final ROW alignment will be placed within the proposed
transmission corridor with great care. Within areas of homogeneous
woodland or clearcut areas the placement of the ROW will te based on
engineering and economic criteria, with suitable attention to
esthetic guidelines of the FERC (FPC 1970). In areas of muskeg or
other wetlands, the ROW will be sited to avoid flight paths of
watertowl. The line will not cross over water or be close enough to
the edge of a water body to block flight pathways. Transmission
pole and line placement will also comply with USFWS guidelines
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_ mouths of salmon spawning streams. --
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The transmission line poles have been designed in accordance
with recent publications on avoiding bird electrocutions (especially
REA 1919). ~here will be no crossbars to invite perching or
nesting, and the uppermost wire will be three feet below the top of
the pole. Most raptors will use the top of the pole for perching.
The alternative placement of wires and their four-foot vertical
separation will render simultaneous contact unlikely •
Clearing of forest for the transmission line will be
accomplished by mechanical removal of the trees. Where the
transmission corridor crosses water courses, trees will te felled
and equipment operated in accordance with USFS policy. For example,
trees within crownheight distance from a stream will be felled away
from the stream, logs and debris which accidentally fall into the
stream will be removed within 48 hours of the incident, and
equipment will not be operated in streambeds (USFS 1911).
Measures to prevent or reduce construction related sediment
damage to aquatic habitat in Black Bear Lake and to salmon spawning
areas in Black Bear Creek upstream of Black Lake are discussed below
in Section 3.1.2.4.
Any tlasting operations required during Project construction
which would occur close enough to tne stream to damage or kill
salmonid eggs or intragravel alevins will be properly scheduled to
avoid serious effects on fish resources. Blasting will nct occur
within a half mile of an active eagle nest during the period March 1
-August 31.
A reservoir filling schedule is proposed which would provide
adequate flows in Black Bear Creek.
operation
The ~ower intake in Black Bear Lake is designed to provide
relatively low water approach velocities for the purpose of reducing
the potential for fish entrainment.
A three-level intake is proposed to minimize changes in the
natural downstream water temperature' regime and effects on fish
populations.
The original discharge regime was modified during project
planning to reduce the potential for significant adverse impact on
downstream fishery resources.
S-31
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Construction of a channel to allow infiltration of a portion of
tailrace discharges into the groundwater system is proposed. It
appears that groundwater provides major inflow to Black Bear Creek I
upstream of salmon spawning areas in the upper watershed (see
Appendix w-B of Exhibit w).
3.1.2.q Protection of water Quality
Construction
During the construction period a major potential effect to
water quality is the possible increased concentrations of suspended
sediments in Black Bear Lake and Black Bear Creek resulting from
construction activities. The potential sources of the sediments
are:
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a. Erosion of excavated areas in the immediate area of the I
damsite,
b. Operation o'f a sump pump to maintain the dewatered area
downstream of the cofferdam at the dam site,
c. waste water trom the washing process required for aggregate
preparation,
d. Erosion of excavated areas in the area of the powerhouse,
e. Stream channel modification and access road construction
between the powerhouse and penstock tunnel portal,
f. Construction and burial of the penstock between the
powe rhouse and tunnel portal, and
g. Excavation of the tailrace channel.
Contribution
excavated tor the
below. Generally
outlet from Black
into the area
water containing
Bear Lake.
of sediments resulting from erosion of the area
dam will be minimized through methods described
the area to be excavated will be dOwnstream of the
Bear Lake. Most ot the drainage will be channeled
immediately downstream of the cofferdam from which
the suspended sediments will be pumped to Black
As a source ot suspended sediments in Black Eear Lake,
discharge from the sump pump will be filtered through a small pool
in the dam construction staging area. Because the staging area will
be constructed of talus excavated from the dam foundation area, it
will be quite porous. It is anticipated that sediments contained in
S-38
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---------------------
the discharge will settle within the staging area and water that
relatively free of sediments will tilter into Black Bear Lake.
As a further precaution to prevent sediments from being
transported to Black Bear Creek, the intake to the diversion culvert
will be extended 50 to 15 ft. into Black Bear Lake. This will avoid
transportation of sediments suspended during construction of the
cofferdam, staging area, and dam to Black Bear Creek.
Potential increases in the sediment load in
resulting from erOSion of the excavated area around
will be minimized by constructing a low berm
construction staging area and Black Bear Creek.
Black Bear Creek
the powerhouse
between the main
waste water from washing of the concrete aggregate will be
discharged through a series of settling ponds prior to release to
the drainage system.
Potential erosion of excavated areas of the buried penstock,
modification of the stream bed and excavation of the tailrace will
be minimized by revegetating areas along the banks as soon as
possitle after distu.rbance.
A potential source of suspended sediments resulting from
construction activities is the excavation of the tailrace channel
and modification of the stream channel upstream of the po~erhouse.
However, the streambed materials in this reacn range trom cobble and
gravel at the powerhouse site to boulder/bedrock at the upstream
end, so that only small amounts ot suspended fines would be expected
to be released by these construction activities. There may be some
minor deposition of fines in Black Bear Creek upstream of Black
Lake, but these deposits would be washed from streambed substrates
by freshets and floods.
Any spills of fuel, oil or grease will be contained within the
-construction staging areas. Bulk tuels would be stored so that no
leaks to the lakes or stream occur. --3.2 Environmental Restoration and Enhancement (Mitigation)
-Proposed mitigation measures are discussed in the following
------
---
subsections.
3.2.1 Terrestrial Habitat and Wildlife Populations
Areas cleared for construction (equipment storage
temporary roads, parking areas, etc.) but not needed for
operation will be revegetated with native plants or
soil-holding ground cover, or allowed to succeed naturally
climax vegetation.
5-39
areas,
Project
with a
to the
I
The transmission line ROW will be artifically seeded only in
arleashwhere slolPe or distufrban~e are ublikelYdto cause s~vlelreb erolslion
d
• •
E sew ere a ow cover 0 natl.ve shr s an grasses Wl. e a owe II
to form.
3.2.2 Aquatic Habitat and ~ populations
It may be possible to place substrate suitable for rainbow
trout spawning in selected areas of Black Bear Lake to replace
spawning habitat inundated when the reservoir is filled. ADFG has
suggested that the inlet stream(s) to Black Bear Lake might be
suitable for such purpose. A limited stocking program is another
potential mitigation measure. ADFG policy does not allow stocking
of non-native rainbow strains in Alaska waters. ADFG has advised
that no source ot native Alaska rainbow strains is ~resently
available, but that facilities are planned which probably would be
able to provide fish for stocking by the time the proposed Project
is scheduled to be constructed. Mitigation measures will be planned
in cooperation with USFS and ADFG.
With-Project modifications in the existing discharge and
temperature regimes in Black Bear Creek will have some ~eneficial
effects. Higher winter flows may increase survival of salmonid eggs
and alevins by decreasing the trequency ot ice formation in the
incubating gravels, especially upstream of Black Lake. Higher
summer tlows may decrease the trequency of occurence ot high water
temperatures which presently occur during dry summers. This would
tend to increase survival of rearing salmonids, but associated
higher water velocities may reduce rearing habitat in certain
reaches.
Water temperatures in Black Bear Creek upstream of Black Lake
could be as much as 1.5-2.0 degrees C above natural tem~eratures
under extreme low winter flow conditions, which can occur in January
and February. Measures which might be employed to reduce with-
Project winter water temperatures include a structure which would
cascade water, a broad and shallow tailrace, a shallow cooling pond,
and selective clearing of streamSide vegetation. However, it should
be noted that removal of streamside vegetation would also probably
increase summer maximum water temperatures.
The feasibility of a small spawning channel downstream of the
Project tailrace will be considered if post-Project salmon
escapement monitoring indicates that such a facility would be of
value. Any spawning channel studies or other appropriate mitigation
measures necessary will be tully coordinated with ADFG, USFWS, NMFS,
and USFS.
S-40
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-..
---... -----...
-----..
-..
--
-
-
4. AGENCY MEETINGS, CORRESPONDENCE, AND TELEPHONE CONVERSATIONS
The following agencies and other entities were consulted during
the Project planning process (see Exhibit W, Section 10 and
Appendix W-D for details).
Alaska Dept. of Fish and Game
Habitat Protection Section
Commercial Fish Div.
Sport Fish Div.
FRED Div.
Game Div.
Alaska Timter Corporation
U.S. Forest Service
Alaska Coastal Management Program
Federal Energy Regulatory Commission
Univ. of Alaska Arctic Environmental
Information and Data Center
u.S. Fish and Wildlife Service
Sealaska Corporation
National Marine Fisheries Service
Alaska Dept. of Environmental Conservation
Alaska A-95 Clearinghouse,
Office of the Governor
Ketchikan Public utilities
Alaska Dept. of Natural Resources
State Parks Div.
Forest, Land, and Water Div.
u.S. Heritage Conservation and Recreation Service
waterfall Group
Alaska Dept. of Revenue
u.S. Environmental Protection Agency,
u.S. Army Corps of Engineers
Tlingit-Haida Regional Electrical Autnority
S-41
u.s. Bureau of Indian Affairs
u.s. Rural Electrification Administration
u.s. Alaska Power Administration
u.s. Bureau of Land Management
Alaska Power and Telephone
International North Pacific Fisheries Commission
u.s. SOil Conservation Service
u.s. National Park Service
u.s. Pacific Marine Fisheries Commission
Cities of Craig, ~lawock, and Hydaburg
Craig Community Organization
Shaan-Seet, Inc.
~lawock Heenya Corp.
Haida Corp.
S-42
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• ------------------------
-
-
s. STUDIES CONDOCTED
The following environmental studies have been conducted or are
being performed by Applicant's consultants and are appended to
Exhibit W as Appendices W-B and W-C.
1. Phase I Aquatic Studies
2. Winter Aquatic Studies
3. Spring 1981 fry trapping
4. 1981-1982 Ecological Work: Interim Report
S. Archeology and Historical Resources Survey
Ecological field investigations, dealing primarily with the
aquatic ecosystem but including mammal populations upstream of Black
Lake, will continue through mid-1982. The Commission will be
provided with copies of the final report as soon thereafter as
possible.
S-43
6. BIBLIOGRAPHY
Alaska Dept. ot Commerce and Economic Development and Alaska Dept.
of Environmental Conservation (ADCED & ADEC). 1979. ~irectory
of permits, State of Alaska. June 1979. Juneau.
I
..
•
•
ilia
Alaska Dept. of Environmental Conservation (ADEC). 1979. Water •
Quality standards. February 1979. •
Alaska Oftice of Coastal Management and u.s. Dept. of Commerce
Office of Coastal Zone Management (AOCM & USOCZM). 1979.
state of Alaska Coastal Management Program and Final
Environmental Impact Statement. Juneau, Alaska, and
Washington, D.C. May 30, 1979.
Avery, M.L.
flight.
(ed). 1978. Impacts of transmission lines on birds in
USDI/FWS/OBS-78/48, 151 p. 578 p. + maps.
Baade, R.T. 19bO. Alaska Dept. of Fish and Game Lake SUrvey Form
and Stocking Record, ADFG Files.
Bates, w. S. 1979. 1976-1978 Klawock River Fish Count. Memorandum
I
I
I
I
of March 11, 1979 to Keith Pratt et al. Alaska Dept. of Fish •
and Game Fisheries Rehabili tation, Enhancement, and ..
Development Division. Klawock, Alaska. 5 p.
" BatEs, w. S. 1980. 1979 Klawock weir count memo to D. Young •
et al., ADFG Files, 6 Aug 1980.
Bell, M.C. 1973. Fisheries handbook of engineering requirements
and biological criteria. Prepared for USACE North Pacific
Division, Portland, Oregon. February 1973. • ..
De Jong, Robert C. 1979. Alaska Dept. of Fish and Game, Division ,
of Commercial Fisheries, Ketchikan. Personal communication to •
Harza Engineering Co.
Elliot, Steve. 1979. Alaska Dept. of Fish and Game, Division of
Sport Fisheries, Project Leader, Juneau. Personal communica-
tion to Harza Engineering Co.
S-44
,
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• ----------------------------
Federal Energy Regulatory Commission (FERC). 1980. Final
Hydroelectric Environmental Impact statement Swan Lake
Project, Alaska. Wash., D.C.
Federal Power Commission (FPC). 1970. Commission Order No. 414 of
27 November 1970.
Galvin, M., K.D. Hoover and M.L. Avery. 1979. Management of
transmission line rights-of-way for fish and wildlife.
Vol. 1. Background information. USDI/FWS/OBS-79/22, 1b8 pp.
Gibbons, D.R., and E.O. Salo. 1973. An annotated bibliography of
the effects of logging on fish of the western United States
and Canada. USDA Forest Service General Tech. Rpt. PNW-10.
Portland, Oregon.
Gibson, D.D. 1976. Bird Species and habitat inventory. Alexander
Archipelago, Alaska, Summer, 1975. Univ. Alaska Mus., Contr.
Rpt. No. 01-283, U.S.F.S., 66 pp.
Hansen, Steve. 1979 and 1980.
Fisheries Rehabilitation,
Division, Klawock, Alaska.
Engineering Co.
Alaska Dept. of Fish and Game,
Enhancement and Development
Personal communications to Harza
Harris, A.S., et ale 1974. The forest ecosystem of Southeast
Alaska. 1. The setting. USDA Forest Serve Tech. Rpt. PNW-12.
Portland, Oregon.
James, B.W., and B.A. Haak. 1979. Factors affecting avian flight
behavior and collision mortality at transmission lines.
Rpt. to Bonneville Power Admin., western Interstate Comm. for
Higher Ed. (WICHE) Boulder, Colo., 109 pp.
Jones, Darwin E. 1978. A study of Cutthroat -Steelhead in Alaska.
Volume 19 Anadromous Fish Studies, Job No. AFS 42-6, July 1,
1977 June 30, 1978. Alaska Dept. of Fish and Game, Sport
Fish Division, Juneau. 119 p.
Kelly, Donald. 1979 and 1980. Alaska Dept. of Fish and Game,
Habitat Protection Section, Ketchikan, Alaska. Personal
communications and letters to Harza Engineering Co.
S-45
Kessler, W.B., 1979. Bird population responses to clearcutting in
the Tongass National Forest of Southeast Alaska. USDA
For. Serve Alaska Reg. Rpt. No. 71,22 pp.
King, J. 1981. USFWS waterfowl biologist, Juneau.
communication to Harza Engineering Co.
Personal
Meehan, W.R. 1974. The Forest Ecosystem of Southeast Alaska.
3. Fish Habitats. USDA Forest Service Gen. Tech. Report PNW-
15. Pacific Northwest Forest and Range Experiment Station,
Portland, Oregon. 41 p.
Meehan, W.R. 1974. The
4. Wildlife habitats.
32 pp.
forest ecosystem
USDA Forest serv.,
of southeast Alaska.
Tech. Rpt PNW-16,
Minore, D. and C.E. Smith, 1971.
north~estern tree species over
For. Serve Res. Note PNW-160.
Occurrence and gro~h of four
shallow water tables. USDA
Portland Oregon. 9 pp.
Muller, M. 1980. Progress report. Phase II. 'threatened and
endangered plants in the Tongass National Forest. USDA For.
Serve unpubl. report. 30 pp.
Murray, D.F. 1980. Threatened and endangered plants of Alaska.
USDA For. Serve and U.S. Dep. Inter., Bur. Land Man. 59 pp.
Rural Electrification Administration (REA) 1979. Fowerline
..
III .,
, 1 ..
• •
• ..
lIP
III
" ..
I
I
I
contacts by eagles and other large birds. REA Bull. b1-10 •
(rev. Mar 79), 7 pp. •
Scott, W.B. and E.J. Crossman. 1973. Fresh~ater fishes of Canada.
Bull. 184. Fish. Res. Bd. of Canada, Ottawa, 9bb pp.
Tlingit-Haida Regional Electrical Authority (THREA). 1978.
Hydroelectric power facilities -legal requirements.
U.S Forest Service (USFS). 1977. Southeast Alaska Area Guide.
Juneau, Alaska.
S-4b
I Ii , ..
-."'"
, ,
I
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-
-
1M -• -• ...
.. -..
-------.. -.. -----..
--..
--
u.s. Forest
Report
Region,
Alaska.
Service (USF S) •
TO'hgass Land
Forest Service,
April 1918.
1918. Fisheries Task Force Working
Management Plan (TLMP-2). Alaska
u.S Dept. of Agriculture, Juneau,
u.S. Forest Service (USFS). 1918 a. Tongass Land Management Plan.
Landtype/Timber Task Force Working Report. USDA For. Serve
TLMP-3, 44 pp. •
u.S. Forest Service (USFS). 1918 b. Tongass Land Management Plan •
Wildlife Task Force Working Report. USDA For. Serve TLMP-6,
41 pp •
u.S Forest Service (USFS). 1979. Tongass Land Management Plan
Final Environmental Impact Statement (Two Parts). Alaska
Region, Forest Service, u.s Dept of Agriculture, Juneau,
Alaska. March 1979 •
Viereck, L.A. and E.L. Little. 1912. Alaska trees and shrubs. USDA
Agric. Handbk. No. 410. u.s. For. Serve Washington, D.C.
2b5 pp.
Walters, M.A., R.O. Teskey, and T.M. Rinckley. 1980. Impact of
water level changes on woody riparian and wetland
communities. Vol. VIII. Pacitic Northwest and Rocky Mountain
Regions. Rep. No. FWS/OBS-18/94. Eastern Energy and Land Use
Team. USDOI. Washington, D.C. 41 pp.
Whitlow, T.H. and R.W. Harris 1919. Flood tolerance in plants: a
state-of-the-art review. U.S. Army Corps of Eng. Tech. Rep.
E-79-2 Vicksburg, Miss. 1b1 pp with app •
Wood, R. 1980. Area Wildlife Supervisor, ADFG, Retchikan.
Personal communication to Harza Engineering Co.
S-41
----
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• -----
-------------------------
Appendix S-A
ACRONYMS
--------ACMP
... AOCED -ADEC -ADFG ..
ADNR ..
l1li ADOL -ADOTPF .. APA -APT -ATC --DOE
-EAR -FERC -HCRS -HECO --NMFS
-OSHA -REA -ROW -THREA -TLMP --USFS
-USF~S -USGS ---
Alaska
Alaska
Alaska
Alaska
Appendix S-A
ACRONYMS
Coastal Management Program
Department of Commerce and
Department of Environmental
Department ot Fish and Game
Economic oevelopment
Conservation
Alaska Department of Natural Resources
Alaska Department ot Labor
Alaska Department of Transportation and Public Facilities
Alaska Power Authority
Alaska Power and Telephone Company
Alaska Timber Corporation
U.S. Department of Energy
Environmental Assessment Report
Federal Energy Regulatory Commission
Heritage Conservation and Recreation Service
Harza Engineering Company
National Marine Fisheries Service
Occupational Satety and Health Administration
Rural Electrification Administration
Right-ot-way
Tlingit and Haida Regional Electrical Authority
Tongass Land Management Plan
U.S. Forest Service
U.s. Fish and Wildlite Service
U.S. Geological Survey
Appendix S-B
GENERAL DESIGN DRAWINGS
OF THE PRINCIPAL STRUCTURES
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GENERAL PLAN
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ALASKA
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ALASKA POWER AUTHORITY
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DWG. NO. 5715-15
-.. -.. -.. -.. -..
-----.. -.. -
---..
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BLACK BEAR LAKE HYDROELECTRIC PROJECT
FERC NO. 5715
EXHIBIT T
A STATEMENT WHY THE PROJECT SHOULD BE DEVELOPED
BY THE APPLI.cANT RATHER THAN THE FEDERAL GOVERNMENT
ALASKA POWER AUTHORITY
ANCHORAGE, ALASKA
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Black Bear Lake
Exhibit T
EXHIBIT T
A STATEMENT WHY THE P:ROJEX:T
SHOUlD BE DEVELOPED BY 'mE APPLICANl'
W.THER THAN THE FEDERAL OOVERNMENI'
A. The Applicant is a public corporation of the State of Alaska in the
Depa.rt:Irent of Cormerce and Econanic Developrent but with separate
and independent legal existence.
B. There exist mmerous potential hydroelectric and fossil fuel
gathering sites in the state.
C • The establishment of power projects at these sites is necessary to
supply p:1Ner at the lowest reasonable cost to the state's municipal
electric, rural electric, cooperative electric, and private
electric utilities, and regional electric authorities, and thereby
to the consumers of the state, as well as to supply existing or
future industrial needs •
D . It has been determined that the achievement of the goals of lowest
reasonable consumer power costs and beneficial long-tenn economic
growth through developrent and operation of power projects in the
state will be accelerated and facilitated by the creation of an
instrumentality of the state with powers to construct, acquire,
finance, and operate pcMer projects. (§ 1 ch 156 SLA. 1978) .
Black Bear lake
Exhibit T
E. A policy of the State of Alaska is to reduce constmer power costs
and otherwise to encourage the long-term econanic growth of the
state, including the developrent of its natural resources, through
the developrent of power projects by creating the Alaska Paver
Authority with powers, duties and functions as provided in Alaska
Statutes, Title 44, Section 44.56.010.
F. There are no existing plans for a wider and rrore ccmprehensive
developrent of any part of the streams and waterways proposed for
inclusion in the Project, and which could be better developed by
the Federal Goverrment.
G. The Project costs will be borne by those deriving direct benefit
fran the Project, as opposed by inposing a tax burden on all U. S.
taxpayers, which would be the case were the Federal Governnent to
undertake the Project.
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BLACK BEAR LAKE HYDROELECTRIC PROJECT
FERC NO. 5715
EXHIBIT V
STATEMENT CONCERNING THE PROTECTION OF NATURAL,
HISTORIC AND SCENIC VALUES IN THE PROJECT AREA
ALASKA POWER AUTHORITY
ANCHORAGE, ALASKA
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BLACK BEAR LAKE HYDROELEC~RIC PROJECT
EXHIBIT V
A STA~EMENT CONCERNING THE PROTECTION OF
NA~URAL, HISTORIC AND SCENIC VALUES IN THE
PRO.1ECT AREA
Exhibit V is contained in Exhibit W, Appendix W-V of this
license application.