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INITIAL INDEPENDENT CONSULTANT INSPECTION REPORT
BRADLEY LAKE HYDROELECTRIC PROJECT
FERC Project No. 8221-AK
ALASKA ENERGY AUTHORITY
OCTOBER 1996
DONALD E. BOWES, P.E.
CONSULTING ENGINEER
BELLEVUE, WASHINGTON
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INITIAL INDEPENDENT CONSULTANT INSPECTION REPORT
BRADLEY LAKE HYDROELECTRIC PROJECT
FERC Project No. 8221-AK
ALASKA ENERGY AUTHORITY
OCTOBER 1996
DONALD E. BOWES, P.E.
CONSULTING ENGINEER
BELLEVUE, WASHINGTON
Section No.
BRADLEY LAKE HYDROELECTRIC PROJECT
FERC PROJECT NO. 8221-AK
INITIAL INDEPENDENT CONSULTANT INSPECTION REPORT
TABLE OF CONTENTS
Description
INTRODUCTION
SECTION I SUMMARY OF SIGNIFICANT FINDINGS
SECTION II DESCRIPTION OF PROJECT FEATURES
SECTION III SUMMARY OF CONSTRUCTION HISTORY AND OPERATION
SECTION IV GEOLOGIC AND SEISMIC CONSIDERATIONS
SECTION V INSTRUMENTATION
SECTION VI FIELD INSPECTION
SECTION VII STRUCTURAL STABILITY
SECTION VIII SPILLWAY ADEQUACY
SECTION IX ADEQUACY OF MAINTENANCE AND METHODS OF
OPERATION
SECTION X CONCLUSIONS
SECTION XI RECOMMENDATIONS
SECTION XII CERTIFICATION
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Section No. Description
SECTION XIII APPENDICES
TabJe No.
IV-I
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A. FERC LETTER APPROVING CONSULT ANTS
B. CONSULT ANT'S SCOPE OF WORK
C. CONSULT ANT'S RESUMES
D. REFERENCES
E. PROJECT DRAWINGS
F. INSTRUMENTATION DRAWINGS
G. PHOTOGRAPHS
LIST OF TABLES
Description
JAN I, 1991 -JAN 1, 1996, EARTHQUAKES-MAGNITUDE 4.0 OR
GREATER
2
BRADLEY LAKE HYDROELECTRIC PROJECT
FERC PROJECT NO. 8221-AK
INITIAL INDEPENDENT CONSULTANT INSPECTION REPORT
INTRODUCTION
This initial independent consultant inspection report was completed in accordance with Federal
Energy Regulatory Commission (FERC) Regulations, Part I 2, Subpart D, that require inspections
and evaluations of hydroelectric facilities to identifY actual or potential deficiencies in the condition
of project facilities, maintenance, surveillance, and operation that might endanger public safety.
Except as required under the provisions of the FERC requirements found in 18 CFR, Part I 2,
Subpart D, the consideration of the safety of the general public, the Alaska Energy Authority's
(AEA) and Homer Electric Association (HEA), Inc.'s employees, or others as visitors or workers at
the project facilities is not within the scope of this inspection. This initial independent consultant
inspection report was prepared by Donald E. Bowes, P.E. The report presents observations of a
two day physical field inspection of project facilities, review of engineering investigations and
analyses as contained in reports available from the AEA, and results of evaluations by the
independent consultant. The scope of the inspection included consideration of major project
structural features and control features in regard to their adequacy against catastrophic failure due
to natural or operational events.
Conclusions regarding the condition and safety of the dam and related major structural features are
not guaranteed, but represent the independent consultant's best judgment based upon this review.
Inevitably, such best judgment must be recognized to be affected to an uncertain degree by the
practical limitations that affect all such reviews and evaluations, relative principally to the
approximate knowledge of the existing properties of the structures and foundations, the reliance on
data and analyses by others as representative of project conditions, and the practical time limitations
of the review process.
This is the initial inspection report to be made pursuant to FERC Order No. 122 (18 CFR Part 12,
Subpart D-Inspection by Independent Consultant).
The physical field inspection of the project occurred on June 26 and 27, 1996.
References furnished by AEA used in the preparation of this report are listed in Appendix D.
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SECTION I
SUMMARY OF SIGNIFICANT FINDINGS
A. FIELD INSPECTION
A physical field inspection was conducted of the Bradley Lake Project (Project) on June 26 and 27,
1996. The field inspection included visual observation of the reservoir and reservoir rim, dam,
spillway including gallery, outlet works, gatehouses and shafts for the outlet works and power
tunnel, powerhouse, tailrace, Nuka Diversion, Middle Fork Diversion, and Upper Battle Creek
Diversion.
The field inspection noted that the concrete faced rockfill dam and the concrete gravity spillway,
the primary water retaining structures, were in an excellent condition and functional for their
intended purpose. No deficiencies were noted related to geologic foundation conditions,
settlement, movement, uplift pressures, seepage or leakage, erosion, or the general condition of the
facilities that would adversely impair their continued safe operation.
No conditions were noted around the reservoir rim that would present a slide hazard sufficient to
create a landslide wave that would be hazardous to the dam.
B. STABILITYEVALUATION
Data and reports on geology, seismicity, construction materials, construction, and stability and
stress analyses by Stone & Webster Engineering Corporation, Bechtel, Corps of Engineers and
others were reviewed for evaluation of the adequacy of stability. The foundations were judged
adequate for the concrete faced rockfill dam and concrete gravity spillway. The seismicity
investigations for the determination ofthe Maximum Credible Earthquake and Design Basis
Earthquake were comprehensive, reasonable, and found acceptable for use in the stability analyses.
The methods of analysis employed for the structural stability analyses of the concrete faced rockfill
dam and concrete gravity spillway were comprehensive, appropriate and acceptable. The factors of
safety criteria adopted for stability are consistent with the general standard of practice of the dam
engineering industry and are acceptable. The computed factors of safety for stability for the
concrete faced rockfill dam and concrete gravity spillway exceeded the adopted criteria minimums
and therefore are acceptable. The structural stresses in the concrete gravity spillway for all loading
conditions were found to be less than the adopted criteria maximum allowable stresses and
therefore are acceptable. Structural deformation criteria for the concrete faced rockfill dam were
found to be acceptable and predicted deformations of the embankment under the earthquake
loading conditions were within the criteria and therefore are acceptable. Deformation of the
concrete gravity spillway on its base is not expected to occur under earthquake loading conditions.
The concrete faced rockfill dam and the concrete gravity spillway are considered stable and safe for
continued use.
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C. SPILLWAY ADEQUACY
Data and reports by the Corp ofEngineers, U.S. Weather Bureau, and Stone & Webster
Engineering Corporation were reviewed for evaluation of the spillway adequacy. The use of
Probable Maximum Precipitation developed by the U.S. Weather Bureau and the use of the Corps'
SSARR model for development of the Inflow Design Flood was found to be acceptable. The
selection of an August PMP with snowmelt only from glaciated areas is acceptable. The spillway
rating curve that was confirmed by model study is acceptable. Routing of the 31,700 cfs Inflow
Design Flood results in a maximum spillway discharge of23,800 cfs at El. 1190.65. The 3.5 feet of
residual freeboard during the peak PMF outflow in conjunction with the wave deflector parapet is
considered adequate to prevent overtopping. The spillway is capable of adequately passing the
PMF.
D. OPERATION AND MAINTENANCE
The Project is operated in accordance with operation manuals and adopted procedures for the
generation of hydroelectric power. The Project was found to be maintained in accordance with
maintenance manuals and adopted procedures and was found to be in a good condition. Planned
maintenance to remove reservoir floating debris, removal of an unstable berm above the power
intake, installation of a permanent tunnel . drain in the outlet works, and installation of an insulated
bulkhead in the North Adit will address these significant maintenance items. It was determined that
the penstock tunnel drains, which are partially plugged with calcite deposits, will need to be cleaned
out to maintain the effectiveness of the penstock tunnel drainage system. Recommendations for
improvements to the surveillance and monitoring activities at the Project are contained in Section
XI.
E. MONITORINGDATA
The survey data related to the movements of the concrete faced rockfill dam and concrete gravity
spillway is plotted on time-history graphs. The data on the graphs indicates limited movements and
no adverse trends. It was found desirable to improve the monitoring and measurement of the flows
from the spillway foundation drains, the concrete faced rockfill dam, and the penstock tunnel
drains. Recommendations for improvements to address these issues are contained in Section XI.
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SECTION IT
DESCRIPTION OF PROJECT FEATURES
The Bradley Lake Hydroelectric Project (Project) is a two-unit, high head (Pelton Wheel)
hydroelectric generation station with a nominal rating of90 MW. The Project is located at the
northeast end ofKachemak Bay about 27 miles from Homer, Alaska. Major facilities include a
dam, spillway, powerhouse, diversion tunnel, power tunnel, barge dock, permanent housing,
airstrip, and three small diversion systems.
The Project is the largest hydroelectric facility in the state of Alaska and the fifth hydroelectric
project constructed by the Alaska Energy Authority. It is designed to generate approximately
365,920,000 kilowatt-hours of electricity annually with average water availability. The two
generators that have been installed were sized with consideration for the possible future installation
of a third turbine generator unit.
A. DAMS AND DIVERSIONS
1. Dam
The dam located just downstream of the natural outlet of Bradley Lake is a concrete faced
rockfill embankment 600 feet in length and 125 feet in height. The upstream and
downstream slopes of the 360,000 cubic yard embankment are at 1.6 : 1. The dam crest is
18 feet in width at El. 1190.0 with a 4 foot high parapet wall of reinforced concrete to El.
1194.0. The parapet wall is integral with a 2 foot 7 inch thick reinforced concrete crest
slab. The downstream slope has a road berm at El. 1077 that provides access to the
diversion tunnel outlet works portal. The reinforced concrete upstream face slab (28 day -
3,000 psi concrete) is nominally 12-inches thick and is supported by reinforced concrete
plinth slabs that are anchored to the rock foundation. The face slabs are nominally 50 feet
in width except at the extreme ends of each abutment. The reinforcement in the face slabs
is #8's at 12 inches on center each way. The reinforcement continues through construction
joints and no waterstops are provided at these joints. The plinths vary in width from just
under 10 feet to 12 feet and range in thickness from 2 foot 3 inches to 2 foot 11 inches.
There is approximately I 0,800 cubic yards of concrete in the face slab, plinth, and parapet.
The reinforced concrete plinths (28 day-4,000 psi concrete) are anchored to the
foundation by # 11 grouted anchor bar systems that vary from 4 rows of 15 foot anchors at
5 foot centers to 5 rows of 15 foot anchors at 4 foot centers. The perimeter joint between
the face slab and plinth does not have reinforcement through it. The perimeter joint is
sealed on the underneath side by a 12-inch double "U" shaped waterstop and on the top
surface by 12-inch-wide rubber conveyor belting anchored with stainless steel bolts and
plates to the surface of the face slab and plinth. Beneath the surface seal, in the void formed
by the seal, a mastic sealant is provided to further make the joint watertight. The
embankment consists primarily of three zones ofrockfill. The majority of the 360,000 cubic
yards of rockfill fill was obtained from excavation of the power tunnel intake. The 12 foot
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wide bedding zone, Zone 1, was obtained from the power tunnel boring machine muck.
The riprap zone, Zone 3, was allowed to vary between 8 to 20 feet in width. The
specifications required the following for each of the embankment zones:
I
(BIA Fill)
2
(B2 Fill)
3
(Riprap)
Gradation
Size %Passing
3 100
1 112 70-100
3/4 50-80
3/8 30-70
4 20-50
10 10-30
40 5-20
200 0-8
max *
24 65-100
18 50-95
4 0-20
200 0-10
Lift
(in.)
12
36
* maximum size function of lift thickness
max
36
1
48
0-30
0-10
Compaction
• 6 passes 10 ton vibratory
• 4 passes 5 ton vibratory on
face surface
• 6 passes 10 ton vibratory
• no compaction placement by
backhoe
The grout curtain under the perimeter plinth is described in Section IV. C. of this report. No
drainage provisions were provided at the dam except the requirement for a 10 foot zone of
very clean rock adjacent to the foundation.
2. Middle Fork Diversion
The Middle Fork diversion redirects the water of the Middle Fork of the Bradley River to
flow into the reservoir instead of its natural course into the Bradley River below the dam.
The diversion consists of an intake basin and a 1, 600 foot long open cut unlined channel to
Marmot Creek which drains into the reservoir. A stilling basin is provided just upstream of
the channel intersection with Marmot Creek.
3. Nuka Diversion
The Nuka Diversion regulates the flow from the Nuka Pool, a small body of water at the
base of the Nuka Glacier. Prior to the Project the entire flow from the pool would flow into
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the Nuka River. The diversion structure is a low (about 5 foot high) gravel filled
embankment on glacial outwash materials at the south end ofNuka Pool that is provided
with twin 12-inch gated outlet pipes to permit a minimum flow of 5 cfs into the Nuka River.
A geomembrane is utilized in conjunction with gabions to form a depressed outlet works
facility for the diversion structure. At the north end of the Nuka Pool, a 100 foot long
outlet weir excavated in rock at El. 1291 was constructed to hydraulically control flows to
the reservoir.
4. Battle Creek Diversion
The Battle Creek Diversion is a low (less than 10 foot high) dike to divert flows from the
upper basin into the reservoir. The embankment is constructed of talus material with a
membrane upstream liner embedded near the upstream slope. Riprap is provided on both
embankment faces to armor the surfaces. A short channel, about 300 feet in length, was
also excavated to improve flow conditions to the reservoir.
B. SPILLWAY
The concrete gravity spillway is located to the east of the concrete faced rockfill dam. It consists of
four distinct sections. The left abutment non-overflow section is 72 feet long and attains a
maximum height of about 3 0 feet to El. 1195.0 at the crest. The crest is 18.6 feet in width. The
upstream face is vertical and the downstream face is vertical from the crest down to El. 1185.0
where it breaks to slope at 0.8 : 1 to the foundation. The right abutment non-overflow section is
30 feet in length and attains a maximum height of 50 feet. The section is similar to the left
abutment non-overflow section. There are two overflow ogee shaped sections with a crest at El.
1180.0 for a total length of 175 feet. The right side is 70 feet in length and about 20 feet in height.
The left side is 1 OS feet in length and a maximum height of about 80 feet above the rock foundation
in a relic riverbed of the Bradley River. The bedrock slope of the foundation under the maximum
section is steeply inclined upstream. The upstream face is sloped 0.3 : 1 and the downstream face is
sloped 0.8 : 1 to a radius transition to the almost flat terminal lip at El. 1134.9, at the downstream
toe. Keyed non-grouted contraction joints are provided at the junctions between the distinct
sections, midway in each ogee section, and one in the left non-overflow section. The contraction
joints are provided with double 12-inch "U" shaped waterstops on the upstream sides and a single
waterstop on the downstream side ofthe ogee sections. Training walls are provided at each end of
the ogee sections and at the contact between the higher and lower ogee sections. A drainage
gallery is provided in the spillway and the seepage is collected and measured in a weir. The grout
curtain and drainage curtain are described in Section IV. C. of this report. There is approximately
11,000 cubic yards of concrete in the spillway structures. The mass of the concrete was 3 1/2 inch
3,000 psi encapsulated in a 1 1/2 inch 4,000 psi outer 3 foot wide zone. The upper 5 feet of the
ogee crest was 4000 psi concrete.
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C. POWERHOUSE
The surface powerhouse is located at tidewater on Kachemak Bay. The structure, founded on
rock, consists of a reinforced concrete substructure and a structural steel super-structure enclosed
with insulated siding and roof. It is 80 feet wide, 92 feet high and I60 feet long. The substructure
extends from El. -9 at the tailrace to El. 42 at the generator floor. The turbine floor is at El. 2I.
Foundation excavation employed smooth wall drill and blast methods and pattern rock bolt
support. Excavation of the rock for a third unit was performed and the area was backfilled. The
two turbines are 45 MW vertical axis, six jet Pelton units with a design head of 1, I 00 feet,
maximum head of I, I75 feet, and minimum head of920 feet. Each turbine is provided with a 60
inch diameter hydraulic oil operated spherical turbine shutoff valve. Each generator has an output
of63,000 KVA at a voltage of 13.8 KV. Frequency is 60Hz, 3 phase with a power factor of0.95
and speed of 300 rpm. The excitation system is solid state. The substation that is tied into an
extension of the north wall of the powerhouse is a compact gas-insulated installation. Three main
power transformers step up the generator output to 1I5 KV.
D. INTAKE AND OUTLET WORKS
The intake and outlet works facilities at the Project consist of a reservoir outlet works installed in
the diversion tunnel outlet and a power conduit system consisting of a tunnel intake, tunnel, and
penstocks.
1. Reservoir Outlet
The reservoir outlet, a low level outlet for reservoir drawdown and fishwater releases, is
located through the rock knob between the right abutment of the dam and the spillway. The
low level outlet is capable oflowering the reservoir to El. 1090 in about 45 days with lake
inflow of 1500 cfs (July Aug. average). The tunnel, a little over 400 feet in length,
originally was an unlined 21 foot horseshoe used for diversion during construction of the
upper project works. The tunnel was later converted to an outlet facility by adding a
concrete lining and construction of a gate control facility at about 1/3 the distance from the
outlet end. The upstream end of the tunnel is provided with an intake structure with two
water passages that can be closed with bulkhead gates. The bulkhead gates, that can also
be installed in the power tunnel intake structure, are provided with a floatation tank system
for installation and removal by divers. The concrete lined tunnel upstream is 7.5 feet in
diameter. An 18 foot diameter concrete lined shaft provides access from the surface at El.
119 5 to the gate chamber that contains two hydraulically operated in-line bonnited high
head slide gates. The slide gates are approximately 7.5 feet wide by 10 feet high. The 11
foot diameter steel discharge penstock extends to the downstream portal. Two 26 inch
diameter fishwater bypass pipes are provided that extend from upstream of the intake
structure to the downstream portal. The fishwater bypass lines are controlled by seven
valves located in downstream tunnel portal service building and are capable of passing up to
100 cfs.
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2. Power Tunnel intake
The power tunnel intake is located upstream of the dam axis about 400± feet on the left
abutment. The intake consists of a large open rock excavation used for the dam
embankment rockfill. The channel invert is nominally El. I 026. Immediately upstream of
the concrete intake structure is an excavated rock trap to El. I 0 I8. The reinforced concrete
intake structure with an invert at El. I 030 is about 60 feet in length and transitions from
two I6 foot wide by 29.5 foot high water passages to the II foot diameter concrete lined
tunnel. Trashracks are provided across the water passage entrances. Two bulkhead gate
slots are provided that are sized to receive the same bulkhead gates that are used at the
reservoir outlet intake portal. The bulkhead gates and floatation tanks are stored outside at
the left abutment of the dam. The power tunnel is controlled by two in-line high head
bonnited slide gates installed in a gate shaft that intersects the tunnel 675 feet downstream
from the intake portal and upstream of the upper vertical bend to the vertical shaft in the
power tunnel. The gate shaft house is located just beyond the left abutment of the dam.
The gate shaft is 22 feet in diameter and concrete lined. The slide gates are approximately
8. 5 feet wide by II feet high and capable of closing under the full generating flow of three
units. Gate speed to close or open is I foot per minute. Tunnel filling and bypass pipe
systems and a tunnel air vent are also provided. The power tunnel intake gates can be
closed locally and remotely from the powerhouse. The gates can only be opened locally.
Power for gate operation is provided primarily by a station service 7,200 volt armored cable
laid on the ground. Backup power supply is a 480 volt, 280 KV A diesel-generator set
located in the power tunnel gate shaft house.
3. Power Tunnel
The power tunnel consists of the following:
• An upper II foot diameter concrete lined tunnel, 738 feet long between the
intake portal at Bradley Lake to the vertical shaft.
• A II foot diameter concrete lined vertical shaft, 720 feet deep.
• A I7,605 foot long 13 foot diameter concrete lined tunnel between the bottom
of the vertical shaft and the powerhouse. The downstream penstock section,
2, 725 feet, is provided with a steel liner encased in concrete. A system of lateral
drains is provided embedded in the concrete of the steel lined section with drilled
drains into the surrounding rock. The downstream 435 feet contains the three
wye-branch manifold sections to the powerhouse.
The upper tunnel and downstream I,400 feet of the lower tunnel were excavated by drill
and blast methods. 16,300 feet of the lower tunnel was excavated using a 15.1 foot
diameter tunnel boring machine. The vertical shaft was excavated using a I3 foot diameter
raise bore. Rock encountered in the tunnel was mostly graywacke with interbedded
quantities of argillite with chert, argillite, and intermixed graywacke and argillite, and dacite.
Rock quality ranged from sound Goint spacing greater than 3 feet) to highly fractured Qoint
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spacing 2 to 12 inches). Most was sound to moderately fractured requiring minimal rock
support and the Bradley River and Bull Moose fault zones did not present any unusual
tunneling difficulties. Occasional intervals of highly fractured rock and narrow shear seams
3 to 12 inches were encountered. Joints open as much as six inches were encountered
immediately upstream of the steel lined section. High pressure grouting of these open joints
was performed for a distance of3,340 feet upstream of the steel liner to a depth of one
tunnel diameter to fill the voids in the rock structure. In addition, reinforcing was added to
the concrete lining for some 2,285 feet in the highly fractured rock zones.
E. MAP OF VICINITY
A map of the vicinity is shown in Figure E-1, Project Location Map.
F. PLAN AND SECTIONAL DRAWINGS
Appendix E contains Figures E-1 through E-19 that show general plans, sections, and details of the
significant project features.
G. STANDARD OPERATIONAL PROCEDURES
The project is operated solely for power generation. It is normally automatically operated by
remote dispatch by Chugach Electric Association from Anchorage via the SCAD A system. It can
also be locally operated from the powerhouse control room. The normal maximum operating
reservoir level is El. 1180, the crest of the agee spillway. The minimum operating reservoir level is
El. 1080. The active reservoir storage between these limits is 285,000 acre-feet.
During floods, the reservoir may rise above the normal maximum operating level to as much as El.
1190.6 that could occur during a Probable Maximum Flood event.
The reservoir may occasionally be drawn down below El. 1080 for purposes of dam foundation
inspection or maintenance.
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SECTION ill
SUMMARY OF CONSTRUCTION HISTORY AND OPERATION
The development of the Bradley Lake drainage basin as a hydroelectric project was first studied by
the U.S. Army Corps of Engineers (COE) as a possible hydroelectric site in 1955 and was
authorized as a federal project in 1962. The Project was further studied by the COE from 1962
through 1982. The COE studies culminated with the issuance in February 1982 of the General
Design Memorandum No. 2 for the Bradley Lake Hydroelectric Project, Reference 10. In addition,
the COE prepared a final environmental impact statement which was issued for review and
comment on August 5, 1982.
Interest in the Project by the State of Alaska (State) began in 1981. The State filed a request with
the U.S. Congress to authorize the Corps of Engineers to design and construct the Project using
State funds. The State initially appropriated $15,000,000 for this purpose. An additional
$15,000,000 was authorized by the State in 1982, at which time the State assumed the Project for
development. Because of the direct State interest and lack of funds from the U.S. Government for
the Project, the U.S. Congress terminated the Bradley Lake development as a federal project in
December 1982. This brought full responsibility for its development under the sponsorship of the
State, and its entity -the Alaska Energy Authority (formerly known as the Alaska Power
Authority). The AEA'S goal was to develop the Bradley Lake Project to fully utilize the
hydroelectric potential of the water within the Bradley Lake watershed.
In April1983, the AEA authorized Stone & Webster Engineering Corporation (SWEC) to
investigate the technical, environmental, costs, and economic feasibility for generating electrical
power to support the energy needs of the Kenai Peninsula and Anchorage regions. In support of
these efforts, an independent Technical Review Board was retained by AEA. This board,
consisting of consultants expert in the fields of geology, geotechnical areas, tunneling and dam
design was retained throughout the engineering-design efforts and through construction.
The October 1983 feasibility study concluded that the preferred development should consist of a
powerhouse located on the Eastern shore ofKachemak Bay and construction of a concrete-faced
rockfill dam at the outlet ofBradley Lake to raise the lake level by 100 feet. The results and
findings from this study became the basis for the preparation of the License Application to FERC
which was submitted in April 1984. The FERC License was granted in December 1985.
AEA awarded the contract for construction management of the Project to Bechtel Corporation
(formerly Bechtel Civil Inc.) in January 1986. The Construction Manager mobilized its staff in
Anchorage that same month and prepared construction procedures and participated with AEA and
SWEC, the Design Engineer, in development of the contract for the Phase I-Site Preparation. The
Construction Manager moved its offices to Homer, Alaska in April 1986, and the Site Preparation
Contract was awarded in June 1986. Work under the Site Preparation Contract began in July and
continued throughout the winter. Two additional contracts were awarded during 1986: the
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Transmission Line Center1ine Survey Contract and the Transmission Line Geotechnical Survey
Contract. All work under Phase I was complete by June I987.
Phase II construction, the General Civil Contract was scheduled to start in July I987, However, in
the spring of 1987, construction was placed on hold pending execution of final power sales
agreements with the Railbelt Utilities. In addition, a statutory change enacted during the 1986
legislative session added a requirement for review of the power sales agreements by the Alaska
Public Utilities Commission. On December I987, the Alaska Energy Authority and the Railbelt
utilities signed final power sales agreements for the purchase of I 00% of the project•s power. In
early I988, the Alaska legislature passed legislation reinstating the exemption of Alaska Energy
Authority wholesale power sales agreements from APUC review. With the resolution of these two
items, the Board ofDirectors ofthe AEA authorized resumption of construction.
Bidding for construction contracts resumed immediately and the camp contract for Phase II
construction was awarded in May I988. The principal contract for the General Civil Construction
Contract was awarded in June I988.
The contracts awarded during Phase II included the General Civil Construction Contract, the
Transmission Line Clearing Contract, the Powerhouse Construction Contract, the Transmission
Line Construction Contract, the Nuka Middlefork Diversions Construction Contract, the Camp
Catering and Support Services Contract and two aviation services contracts. Construction
continued year-round and all major facilities were essentially IOO% complete by June I99I.
Startup of the two turbine generator units commenced in May I99I and both units were declared
ready for commercial operation September I, 199I. The final onsite work consisted of
revegetation and restoration which was performed by the Site Rehabilitation Construction
Contractor. This contract was awarded in June I99I and completed in November I991.
The project has commercially operated since September 1, 1991. Significant operational events
since then are:
• The spillway discharged during the period October I-3, 1991, and the maximum flow
was 512 cfs.
• In March and April of 1992, the Project tunnel was dewatered for inspection following
discovery of concrete, grout, and rock debris in the discharge pit of turbine unit No. 2.
• Four earthquake events ofMS or greater have occurred in the general vicinity as
follows:
Date
I2/7/91
3/19/93
12/11/93
4/25/94
Magnitude
5.20
5.IO
5.00
5.40
The epicenter location of each event is reported on in Section IV. E.
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SECTION IV
GEOLOGIC AND SEISMIC CONSIDERATIONS
A. REGIONAL GEOLOGY
The portion of the Kenai Mountains in which the Project is located is composed of upper
Mesozoic Age metamorphic rocks of the McHugh Complex. Figure E-20 presents a map of
the regional geology. Contrasting depositional environments, mode of deformation and
general lack of continuity of units indicate that the McHugh Complex, including the Bradley
Lake area, represents a melange deposit in which rocks have been tectonically mixed,
uplifted, deformed, and accreted onto the North American Plate.
The primary tectonic influence on the Project area is the Aleutian Arc-Trench, which lies 185
miles southeast ofBradley Lake, and parallels the prevalent northeast-southwest strike of the
prominent tectonic features found in and around the Project area. Figure E-21 is a map of
Southern Alaska Regional Faults.
The Aleutian Trench is a result of the northward movement and underthrusting of the Pacific
Plate beneath the North American Plate, at an estimated rate of about 2.4 inches per year.
The resultant subduction zone, called the Aleutian Megathrust, dips to the northwest and
corresponds to a zone of seismic activity called the Benioff zone.
B. LOCAL GEOLOGY
The tremendous forces operating on the area during accretion created large tectonic features,
and also imparted the melange and cataclastic structures on the rock, as manifested by the
intimate shearing and flow mixing of a graywacke, argillite, metatuff and chert. This occurs
at all scales ranging from tenths of an inch to hundreds of feet.
The compressional stresses inferred to have been responsible for the geologic structure at the
Project area do not appear to be active at this time. Although the overall stress regime for
the Southcentral Alaska Area is compressional on a generally northwest-southeast axis, the
current configuration of plate boundaries and the location and orientation of the subduction
zone suggest that the regional stress regime of the Kenai Peninsula is, at least temporarily, in
a low stress situation. Hydrofracturing tests conducted along the pressure tunnel alignment
indicted that horizontal stresses are less than the vertical stresses.
1. Surficial Deposits
Unlithified surficial deposits in the Project area consist of glacial till and outwash,
colluvium, alluvial channel, flood plain and deltaic deposits, peat and marine intertidal
deposits as shown in Figure E-22.
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Locally these deposits and bedrock may be overlain by an organic mat generally not
more than three feet thick, consisting of moderately to poorly drained silty loam soils
with 112 in. to 1 in. layers of volcanic ash, and moderate to high organic content.
Peat deposits 1 -10 ft. thick are found in topographic depressions and poorly drained
areas that are generally saturated and characterized by lack of deciduous vegetation.
They typically surround small ponds and locally, may be separated from bedrock by a
thin layer of gravel till.
Alluvial gravels and cobbles in a matrix of silt and sand occur as stream channel, flood
plain deposits 5 -40 ft. thick. Gravel to boulder size talus with occasional very large
blocks, derived primarily from argillite and graywacke, occurs within colluvial
deposits. These deposits lie below steep slopes and rock exposures, such as at the
damsite and in the Bradley River gorge areas.
Deltaic deposits such as those at Battle Creek and Martin River are believed to
average at least 40ft. thick. These deltaic fan deposits are composed of braided river
deposits superimposed on deltaic sediments. Sediments in the Martin River delta vary
from gravel with sand and cobbles to sand with gravel and occasional silt layers. The
upper (near surface) portion of the delta generally consists oflarger gravel with less
sand than in the deeper portion of the delta.
Colluvial deposits consisting of sand to boulder size clasts in a silt matrix are
generally 5 to 1 5 ft. thick. Colluvium may overlie other unlithified deposits and is
commonly found along and below slopes.
Glacial tills composed of poorly sorted silt, sand, gravel and cobbles are found along
the shore ofKachemak Bay from Sheep Point to the Bradley River. The thickness of
these deposits vary from zero to greater than 40 feet.
2. Bedrock
The basic rock types identified in the Project area are graywacke, argillite, chert,
dacite, metatuff, and greenstone. A detailed lithologic description of each rock type
follows.
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a. Graywacke
Graywacke is a dark gray, coarse-grained sandstone containing poorly sorted
angular to subangular grains of quartz, feldspar, dark minerals and lithic
fragments in a silt and clay matrix.
The rock is generally massive and homogeneous, and displays no visible
bedding. It is very poorly foliated to unfoliated, but may be locally strongly
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jointed, with weathered and stained joint surfaces extending up to 100 ft.
below ground surface. Discontinuous veinlets of quartz and calcite, generally
less than 0. 4 in. wide and 2 -12 in. long, are common.
As the grain size and sand fraction of the graywacke decreases, the graywacke
characteristics grade toward those of argillite. In addition, soft-sediment
compositional mixing between components of argillite and graywacke parent
material creates a gradational series that combines the properties of the two
end members.
b. Argillite
The argillite derived from mudrock, lacks fissility, is more highly indurated
than shale or mudstone, but is not metamorphosed to the degree of slate and
does not have the cleavage of slate. The argillite is a charcoal-gray to black
rock composed of silt and clay-size grains with very few or no sand grains.
The argillite is generally fresh to moderately fresh and moderately hard.
Moderately weathered material may be soft. Bedding is rarely seen, and
where visible, is poorly preserved. White quartz and calcite veinlets up to
about 0.8 in. in thickness are common. Most weathering develops along
fracture and foliation planes which may penetrate deep into the rock mass.
The effects of weathering generally do not extend more than 0.05 in. from the
plane.
c. Chert
The chert in the Project area, appears to occur most commonly as light to
dark gray nodules, lenses and massive layers in the argillite and metatuff. The
nodules are rounded and commonly have diameters ranging up to 6 in.,
although a few 40-in. thick nodules were noted. The nodules are elongated
parallel to the foliation in the argillite, which is deformed in curves around the
chert nodules.
d. Dacite
The dacite, a fine grained igneous rock, is very hard to extremely hard and
generally fresh. No foliation is visible and joints are generally well developed.
Several dacite dikes are structurally deformed (faulted and folded) but are
generally continuous over a considerable length, and none display evidence of
having undergone as extensive a deformational history as the surrounding
country rock. The widths of the dikes range from 1 to 40 feet, generally not
exceeding 1 0 to 20 feet in width.
IV-3
e. Metatuff
Metatuff, a rock composed of metamorphosed pyroclastic volcanic debris, is
common throughout the McHugh Complex. In the Project area two varieties
of metatuff were mapped, but comprise less than 5% of the total rock
encountered in the investigations. Type I is megascopically described as pale
green in color with a dull, earthy luster, and is intimately associated with
argillite (mixed in approximately 0.05 in. to 1 in. discontinuous layers).
Engineering properties are similar to argillite, and foliation is generally well
developed. This variety represents a distinct but minor portion of the mapped
metatuff The metatuff Type II variety is green to light gray in color, appears
more massive in the field (occurring in 1 to 15 ft. thick layers), and is also
associated with argillite. Engineering properties of the Type II metatuff are
similar to those of graywacke, in that it is generally hard to very hard, strongly
jointed, and poorly foliated. Chert nodules and lenses up to several feet thick
are commonly associated with the metatuff.
f Greenstone
Greenstone is a field term generally applied to a dark green, metamorphosed,
basic igneous rock that owes its color to the presence of chlorite, epidote, or
actinolite. The units mapped as greenstone comprise less than 3% of the total
rock encountered in investigations. The greenstone is dark green, very hard,
massive, has a high specific gravity, and exhibits slightly iridescent weathering
surface with a reddish tinge. The greenstone occasionally displays a pillow
basalt type structure and it strongly jointed but not foliated. The greenstone is
interpreted to have been subject to cataclasis but does not exhibit the
extensive deformational effects of the other rock units in the project area. In
addition, the greenstone does not occur intermixed with argillite, graywacke,
or chert and appears to have an origin distinct from that of the other rocks in
the Project area.
C. FOUNDATION CONDITION
The following descriptions of foundation conditions under the dam, spillway, diversion
tunnel-reservoir outlet, intake, and powerhouse were obtained from the, Final Construction
Geology Report, Reference 5. Emphasis in this report is on the dam and spillway structures
retaining the reservoir.
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1. Dam
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a. Foundation Excavation
Foundation materials excavated in the river channel consisted of alluvial
deposits and localized areas of glacial till. On the lower half of the left
abutment slope, excavated materials consisted of colluvium and talus deposits
whereas on the right abutment bedrock was exposed.
The thickness of the excavated alluvial deposits was variable. It ranged from
as much as 15 feet in a buried bedrock channel near the upstream toe on the
east side of the existing river channel to generally one to three feet elsewhere.
Excavated talus and colluvium deposits, which extended from the river
channel to approximately 200 feet up the slope of left abutment, were as much
as 10 feet thick locally, but more generally one to three feet thick. The
quantity of talus excavated from the lower right abutment was relatively
minor. The stripped bedrock foundation surface in the river channel area,
with the exception of a large depression near the plinth line, was highly
irregular, pock marked with large and small potholes and elongated, shallow,
narrow erosion channels. Foundation preparation for the river channel portion
of the embankment foundation consisted of machine cleaning of the bedrock.
Rock excavation and rock surface preparation beneath the embankment
portion of the dam was minimal. On the upper two-thirds of the right
abutment slope, bedrock was widely exposed, as was the upper third of the
left abutment.
Requirements for excavation and rock surface preparation of the plinth
foundation were considerably more stringent than for the embankment
foundation. The depth of acceptable foundation rock varied, but in general
rock excavation ranged from a few feet to as much as 10 feet below the
original rock surface. Foundation excavation removed all the weathered,
unsound rock as well as providing for a more uniform slope transition from
one plinth segment to another. Careful controlled blasting was done to avoid
excessive fracturing of the plinth foundation. Some over excavation occurred
in portions of some plinth segments. Preparation of the foundation for
concrete included scaling of all rock fragments loosened by blasting and
cleaning with high pressure water jets. The actual foundation width prepared
for detail cleanup was approximately 15 feet. An additional 10 to 20 feet of
natural rock surface upstream of the plinth foundation was also sufficiently
cleaned to permit inspection and delineation of any geologic features which
could affect foundation treatment including curtain grouting. Minor quantities
oflean concrete were placed locally in a number of plinth blocks to level out
sharp irregularities in the plinth foundation. A dozen or so thin shear seams 6
to 12 inches wide crossed the plinth foundation. Several of the wider seams in
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plinth foundation segments in the upper left abutment required minor
foundation dental treatment, i.e. excavation to twice the width and filled with
concrete.
Owing to the weathered condition of the rock above an open joint near the
top ofthe left abutment, approximately 60 cu-yd of rock was removed and
subsequently replaced with concrete. At final excavation depth, the aperture
of this particular joint was 1 to 3 inches. Borings for washing the joint were
drilled further up the slope. Return water from the open joint did not appear
for a couple of hours. The joint was only weakly responsive to air-water
jetting. Special attention was given to treating this open joint during
foundation grouting.
A prominent erosion channel that crossed the plinth foundation at the east end
of the river channel section at the base of the high rock face on the right
abutment was found to be deeper than expected. At approximately El. 1038
the width of the rock channel narrowed from 8 to less than 4 feet and was
filled with densely compacted boulders and gravel. Exploratory rotary
percussion holes revealed infill bottomed at El. 1034. To facilitate infill
removal, additional rock excavation by drilling and blasting was done. After
excavation and cleanup, the shear seam along the bottom of the erosion
channel at El. 1032 was found to be tight and less than 6 inches wide.
Concrete backfill was placed in the over-excavated erosion channel.
For the most part, the final plinth foundation on the right abutment was
excavated and constructed along a narrow 4 to 5 ft., 30° upward sloping
bench which had been drilled and blasted from the high precipitous rock face.
With one exception, the condition of the rock both in slope stability and
soundness was very good. Approximately two-thirds up the right abutment
plinth slope, additional rock excavation was required in a 30-ft. wide zone. It
was necessary to remove highly weathered, fractured and blocky rock
associated with an open joint along one side of a huge, massive rock wedge.
At the plinth foundation grade, the open joint pinched-out and was tight.
However, upstream ofthe plinth the joint was 6 to 10 inches wide and was
infilled with silty gravely sand up to the ground surface. Dental treatment of
this open joint consisted of excavation of the infill material down one to two
feet all along its surface exposure (approximately 50 feet) and backfilling with
small aggregate concrete.
b. Bedrock
Geologic mapping was limited primarily to the plinth foundation where the
excavated rock surface had been cleaned and prepared for concrete placement.
Machine cleaning of the foundation surface beneath the rock-fill embankment
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limited mappable exposures to gross geologic features. However, close
inspection of the machine-cleaned foundation surface did not reveal any
significant geologic features such as faults or soft materials. Where evident,
lineaments were approximately N 10 W and almost vertical, joints were
approximately N 84 W dipping S 84 and N 25 E dipping E 72. Several
narrow erosion channels and a number of large, shallow potholes were
present. The most prominent, undulating scour channel of I to 3 feet in depth
is located along the base of the right abutment rock knob. It extends perhaps
50 feet upstream and downstream of the dam axis. Some of the scour
channels were filled with dense clay till, others were infilled with densified
sandy gravel. The orientation of the erosion channels appeared to be
controlled by north-trending joints.
The portion of the embankment foundation in the river channel and on the
right abutment is almost entirely graywacke. Rock quality is good;
weathering is minor. Primary joint spacing where it could be seen appears to
be spaced several feet apart. Although the surface of the massive rock knob
forming the right abutment had been discolored by weathering, the penetration
depth of weathering is generally less than 12 inches. Above the channel on the
right abutment, jointing on the precipitous rock wall is widely spaced, ranging
from a few feet to as wide as I 0 feet or more. Foundation preparation for the
rock-fill embankment against this right abutment area was minimal.
On the left abutment slope above the river channel, graywacke predominates,
but localized areas of argillite within the graywacke mass occur also. Exposed
foundation rock on the left abutment after stripping was moderate to locally
highly weathered.
The dam plinth foundation consists of fresh to slightly weathered graywacke.
The foundation rock is sound, but closely jointed, without major geologic
defects. Minor defects were encountered in the form of shear seams 6 to I2
inches in width, most with intercalated I to 3 inches wide, discontinuous clay
layers. In the upper left abutment plinth and the right abutment plinth, open
joints were uncovered. These were treated by cleaning and grouting or
partially excavating and filling with dental concrete.
c. Grouting
A single line grout curtain was completed through the concrete plinth along its
entire length. The left and right abutment grout curtains were extended I60
and I20 feet, respectively beyond the ends of the dam. The split spacing
method was used with the initial holes at 20-foot spacing and ranging in depth
from a minimum nominal 30 to 90 feet. The secondary holes were at 20-foot
spacing midway between the initial holes and were nominally three-quarters
IV-7
the depth of adjacent holes. Tertiary holes, where necessary, were one-half
the depth of the initial holes. The curtain was inclined upstream 30 degrees in
the left abutment and river channel section and 45 degrees into the right
abutment. At the toe of the steep right abutment a fan type of grout hole
arrangement was utilized.
Details of the dam foundation grouting are given in Reference 4. For this
report, a generalized profile of the dam drilling and grouting program is
shown in Figure E-24. Included on the profile in the figure and in the notes is
a summary of grout takes by plinth segment. An approximate total of 680
sacks of cement were injected in the dam plinth foundation. Of this total
approximately 85 percent ofthe sacks were injected in three holes. The
majority of the grout holes were tight, taking no grout or a nominal amount.
Grout take in the left and right abutment extensions were approximately 186
and 1,327 sacks, respectively. One hole on the right abutment extension took
736 sacks.
d. Drainage
There were no provisions for dam foundation drainage downstream of the
plinth and grout curtain.
2. Spillway
The length ofthe spillway structure at the crest is 277 feet. Curtain grouting was
performed from the foundation rock surface. Drainage holes located in a gallery at
the base of the spillway structures were drilled prior to completion of gallery roof
construction. A plan and section of the spillway is shown in Figure E-6.
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a. Foundation Excavation
The concrete gravity spillway structure was constructed across a narrow rock
saddle between the massive rock knob forming the right abutment of the dam
and the almost vertical rock cliff rising from the base of the mountain mass to
the east. Crest elevation at the non-overflow abutments of the spillway is EL.
1090 and the overflow ogee crest is El. 1080. At the east abutment, there was
a notable deep erosional feature at the base of the spillway right abutment.
The erosional feature consisted of a deep, enclosed depression 15 to 25-ft.
wide incised upstream by a deeper, narrower channel 2 to 5-ft. wide. The
channel was filled with dense alluvial deposits. The lowest, elevation of the
excavated incised channel at the upstream toe of the spillway was
approximately 3 5 feet lower than the bedrock surface at the downstream toe.
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West of the erosion channel to the end of the spillway left abutment, the
stripped rock surface was highly uneven, in part due to past glacial action and
in part to differential weathering. Drilling and blasting was necessary to
remove excessively weathered, blocky rock and to satisfy design foundation
elevations. In several local areas over-excavation of up to 10 feet was
necessary to reach suitable foundation rock conditions.
A high precipitous rock face existed on the right abutment of the spillway.
Although the rock was massive and of good quality, the design called for a
thin slice ofrock to be removed to develop a bench at the base at El. 1145.
The rock slice was removed by pre-split blasting resulting in a continuous,
even surface. Final foundation preparation included detail scaling ofloose
rock materials and cleaning of the foundation surface with pressurized air and
water jetting.
b. Bedrock
Bedrock in the spillway consisted entirely of graywacke. Lineation and
jointing was similar to the dam foundation. At foundation grade the rock was
generally fresh to slightly weathered for a I 00-ft. wide section east of the
spillway right abutment including the deep erosion channel and the precipitous
rock face. Over the next 175 feet of foundation to the end of the spillway left
abutment, weathering was slight to moderate. The dominant geologic
structure is the strong repetitious northwest trending joint system. This joint
system prevails across the entire spillway foundation. Over most of the
foundation area this persistent jointing was reasonably tight. Notwithstanding
the generally tight jointing, there were a number of short sections (less than 5
feet) of individual joints that were open 1/2 to 2 inches in otherwise sound
rock. The extent of the openness of these joints was further demonstrated by
the relatively high grout takes in several holes during foundation curtain
grouting.
Special seam treatment was done in the incised channel and in several local
areas where inverted V -shaped, elongated rock projections occurred in the
foundation. Lean concrete was utilized to fill and even out these and other
near surface irregularities. Several other shear seams, 3 to 12 inches wide
were mapped in the final spillway foundation. Two of the seams traversed the
full width of the foundation. The seam material consists mainly of finely
fractured rock materials discontinuously interspersed with minor clay. As part
of the foundation preparation, these seams were scaled and washed with air
and water jets to a tight surface.
IV-9
c. Grouting
Curtain grouting and contact grouting was performed at the spillway and the
spillway grout curtain was tied into the extended dam right abutment grout
curtain. The grout curtain was generally located a minimum of 5 feet
downstream of the spillway upstream heel contact. The grout program was
similar to the program for the dam using the split spacing procedure with
initial, secondary, and tertiary holes. The initial, hole spacing was 20 feet.
Depth of grout holes varied from a minimum nominal of 30 feet to 2/3 the
maximum head for the initial holes, 1/2 the maximum head for the secondary
holes, and 1/3 the maximum head for the tertiary holes. The grout curtain
between the left abutment and base of the right abutment was inclined 30
degrees upstream. At the base of the right abutment a fan layout of holes was
utilized and in the right abutment the curtain holes were 15 degrees from the
horizontal in an easterly direction. A profile of the grout curtain is shown in
Figure E-25. As indicated on the figure, most of the grout take was
consumed in seven holes; takes ranged from 93 to 3 56 sacks. These large
grout takes closely corresponded to mapped locations of open joints in the
spillway foundation.
d Drainage
A drain curtain was provided along the alignment of the drainage gallery
trench. The drain holes were nominally spaced on 5 foot centers. Between
the spillway left abutment and the base of the spillway right abutment the
holes were a 30 feet deep from top of rock or the drainage gallery floor. In
the steep right abutment a fan arrangement was utilized with 6 -60 foot and 4
-50 foot deep holes at approximate El. 1135.
D. FAULTING
The Project area on the North American Plate is situated on an overriding crustal block
above the Benioff subduction zone. The Border Ranges Fault marks the northern margin and
suture line of the McHugh Complex, while the Eagle River Thrust Fault and adjacent Valdez
Group rocks mark the southern limit of the complex. In the vicinity of the Project, the
Border Ranges Fault lies under Kachemak Bay, and the Eagle River Fault crosses Bradley
Lake near its head. Both faults trend northeast-southwest. Within the Project area, the
locally prominent Bradley River, Bull Moose and Battle Creek Faults, as well as a complex
network of secondary faults, fracture zones, and major joint sets are expressed by lineaments
that generally parallel the same regional structural grain.
The Bradley River Fault and the Bull Moose Fault cross the power tunnel alignment about
4,200 ft. and 11,600 ft., respectively, from the intake area at Bradley Lake as shown on
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Figure E-8. The Battle Creek Fault strikes north-south and cuts across the base of Sheep
Point.
The proximity and parallel orientation ofthe Bradley and Bull Moose Faults and associated
lineaments, with respect to the two major regional fault systems which flank the Project area,
suggest they share a common relationship and response to the tectonic regime of the region.
Definitive data on the Border Ranges, Eagle River, Bradley River, and Bull Moose Faults is
scarce. None of the Project investigation studies noted evidence of recent displacement on
these faults. Microearthquake data available at the time of the studies did not reveal an
association between recorded seismicity and the mapped faults in the Project area. In fact,
the limited seismic activity appeared to be at a crustal zone depth shallower than the
subduction zone which is thought to be the primary source of seismic activity. Some
evidence has been found to suggest recent activity on the Eagle River Fault near Eklutna,
some 125 miles northeast.
If the Border Ranges or Eagle River Faults are active, it was concluded that displacement on
either of them could potentially induce movement on the Bull Moose or Bradley River Faults,
or on other associated small faults in the Project area. In addition, independent stress-related,
fault rupture was reported as possible on the Bradley River or Bull Moose Faults, with
amounts of predicted slip ranging from 3 in. to 48 in. The probability of measurable
displacements occurring on these faults at any time in the next 1 00 years is estimated by
Woodward-Clyde Consultants to be in the range of one in 250 to one in 5,000, Reference 3.
E. SEISMICITY
As noted earlier, the primary large-scale expression of the tectonic influence on the Project
area is the Aleutian Arc-Trench.
At the Project area, the Benioff zone lies about 30 miles beneath the earth's surface. This
zone marks the boundary between the two colliding lithospheric plates, is an indicator of
substantial regional tectonic activity, and has been the focus of several major historic
earthquakes in southern Alaska. Historically ( 1899 to date), eight earthquakes ranging from
Richter magnitude Ms=7.4 to 8.5 have occurred within 500 miles of the Project.
Great earthquakes (surface wave magnitude Ms=8 or greater) and large earthquakes (greater
than Ms=7) have occurred historically throughout the region and can be expected to occur in
the future.
Because of this active tectonic environment, activity is also probable on other faults, such as
those found near or within the Project area, located in the overriding crustal block above the
subduction zone and between the known active faults.
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1. Design Earthquakes
The design earthquake studies for the Corps ofEngineers by Woodward-Clyde
Consultants, Reference 3, examined possible earthquake sources and associated
maximum magnitude estimates for each source zone. The studies concentrated on
regional faulting, (the Aleutian Megathrust/BenioffZone), and four local faults (the
Eagle River, Border Ranges, Bradley River, and Bull Moose Faults) as the controlling
sources to be considered. Analysis indicated that a magnitude 8.5 event occurring on
the megathrust beneath the site and a magnitude 7.5 event occurring on the Border
Ranges or Eagle River Faults, dominate the total response spectra for design. Seismic
design parameters were developed for what the Corps terms the "design maximum
earthquake" and the "operational base earthquake" (herein called Maximum Credible
Earthquake and Design Basis Earthquake, respectively). The Maximum Credible
Earthquake (MCE) is defined as the most severe earthquake believed to be probable
which could affect a site. The Design Basis Earthquake (DBE) is less severe, and is
defined as the seismic level which is considered as likely to occur during the life of a
project.
Based on their work on the seismicity of the site, WCC proposed two possible
response spectra for the "design maximum earthquake", the equivalent of the MCE.
The one which was expected to control was based on rupture of one of the faults
nearest the site. The resulting earthquake would have a magnitude ofMs=7.5. The
other possible MCE was a Megathrust event tied to the Benioff Zone roughly 30
miles beneath the site. This event would have a magnitude ofMs=8.5. It was not
expected to be the controlling event unless the faults in the immediate vicinity of the
site could be shown to be inactive.
A third response spectrum proposed by WCC was an event with a peak ground
acceleration approximately one half that of the MCE (0.35g) for use as the DBE.
A summary of the selected earthquake parameters follows:
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0.55
0.35
21.6 1.3
10.1 0.61
45
45 (DB E)
IV-12
Since all critical structures of the Project are founded on bedrock, accelerograms
recorded on rock from large magnitude earthquakes having similar peak parameters
to those listed above for the crustal event would ideally be used for the required
analyses. At the time the studies were performed, no accelerograms recorded on rock
in the near field oflarge magnitude earthquakes (Ms=7.5) were available from
anywhere in the world, including Alaska. Consequently, available accelerograms from
historical earthquakes having appropriate peak and spectral characteristics over a
broad period range, even when scaled, were not available for use.
Since no actual accelerogram was available, a composite hybrid accelerogram was
derived by SWEC for the dam stability analysis from the historical accelerograms of
two earthquakes having appropriate characteristics. This approach has been
previously used for other studies, including those performed by the California
Department ofWater Resources for Oroville Dam, and is considered an appropriate
state-of-the-art method for simulation of strong motion events.
After examining the response spectra for recorded accelerograms from a number of
earthquakes in the United States and abroad, it was concluded that a suitable
accelerogram for the Ms=7.5 crustal event could be obtained. The resulting
accelerogram, called the Hybrid record, is shown on Figure E-26. The significant
duration of the Hybrid record is 28.8 seconds, which is slightly longer than the 25
second MCE proposed by WCC. This longer event duration, when combined with
the greater density of high acceleration peaks from the combined records, results in a
design record that is conservatively intense and definitely on the "safe" side when
used to simulate the project MCE.
The critical structures and equipment including the main dam, spillway, low level
outlet gates and operators, power tunnel, power tunnel intake and intake gate shaft,
intake gates and operators, and spherical valves and operators are designed for the
MCE. Some repair may be required after the event. However, the operating integrity
of these structures and equipment is expected to be maintained during the MCE.
The powerhouse is designed for the DBE with some repair possible after the event
and for the MCE with significant damage possible but no collapse.
The Project has two seismographs installed that are part of a local network of 12
stations that record all events ofM 1.5+. Four events ofM 5+ that have occurred
within a 100 mile radius of the Project have been recorded and these are shown in
TABLE IV-I along with other events ofM 4+ since January 1, 1991. Review ofthe
list indicates that all of theM 5+ events are beyond a 50 mile radius of the Project,
which is the distance criteria limit for notification of an earthquake event to FERC for
projects in Alaska.
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3. Tsunami Hazard
Project facilities including the powerhouse and barge dock could experience a tsunami
associated with earthquake or volcanic activity. The probability of such an event
occurring sometime during the 50-year design life of the Project is low. The wave
height of a tsunami, with an annual probability of occurrence of 0. 007, the same as
the DBE, is approximately El. 25. This design case resulted in a total dynamic force
of 192 kps/ft that was applied in the stability analyses and structural design of the
west wall of the powerhouse.
4. Reservoir Seiche Hazard
A delta area within the reservoir was identified as most likely to experience a landslide
during a major earthquake. An estimate was made of the volume of material in the
delta which might liquefy during an earthquake, causing a subaqueous landslide, and
thereby inducing a seiche wave in the reservoir. The 4,000,000 cubic yard estimated
mass mobilized during this postulated subaqueous landslide would be a 200 foot wide
band along two-thirds of the 5,500 foot width ofKachemak Creek delta. The MCE
event was used to generate the landslide.
The magnitude of the wave which would be generated by this landslide and the
propagation of the wave approximately three miles along the lake to the dam was
estimated. The use of three wave propagation methods yielded similar results, the
largest of which indicated a 9. 7 foot wave height at the dam. The analysis was
performed with the lake water surface at elevation 1180, the maximum normal
operating level. No reduction in wave magnitude was made for the attenuating effect
that the southwest portion of the lake shoreline, which juts out in front of the dam
blocking the path of the wave. The analysis showed that the dam parapet with its
wave deflector would not be overtopped and that the wave force would be less than
that for which the parapet and crest were designed.
F. SINKHOLE POTENTIAL
The type of bedrock at the Project area does not have the characteristics of the type of rock
that is subject to dissolution with associated sinkholes. No sinkholes were reported in the
Project area as a result of geotechnical investigations.
PAEABL07
10/ll/96 IV-14
PAEABL07
10/12/96
JAN 1, 1991-JAN 16, 1996
EARTHQUAKES-MAGNITUDE 4.0 OR GREATER
org_time mag 1at 1on dep
---------------------------------
910411 12:30:43.66 4.10 59.64 -152.78 92.39
910421 09:24:25.82 4.10 60.30 -152.99 12.00
910825 04:32:13.69 4.00 60.07 -152.07 64.33
911205 03:52:07.26 4.10 59.62 -152.44 67.47
911207 11:42:29.73 5.20 60.95 -150.33 58.87
910219 08:19:20.81 4.30 60.96 -150.94 8.14
920120 10:26:08.54 4.20 60.10 -152.88 11.00
910613 01:22:46.98 4.90 59.81 -152.05 34.17
910622 02:34:11.88 4.40 60.44 -152.31 10.00
920615 10:46:12.50 4.10 59.15 -152.50 77.55
920319 15:06:01.44 4.20 60.12 -152.03 85.59
930202 07:35:10.18 4.70 59.08 -152.30 78.44
930212 00:30:35.03 4.00 60.00 -152.25 89.07
930319 12:20:51.11 5.10 59.54 -152.87 10.00
911108 05:28:02.73 4.60 60.73 -151.92 8.00
921127 16:46:50.06 4.20 60.19 -151.78 62.95
930507 00:52:37.39 4.50 50.31 -152.40 90.37
930720 00:42:56.54 4.40 60.35 -152.28 80.69
931211 00:07:23.07 5.00 59.56 -152.5 72.30
940201 20:20:03.93 4.10 59.83 -150.66 1. 00
940301 05:03:09.02 4.30 59.74 -152.72 92.23
940305 23:08:58.53 4.00 59.31 -152.53 73.29
940412 02:42:35.46 4.10 59.92 -152.65 86.86
940425 00:19:07.78 5.40 60.81 -151.03 48.88
940521 02:22:19.06 4.70 59.47 -152.78 9.00
940823 14:33:52.83 4.70 59.06 -152.40 87.72
940825 02:56:25.14 4.30 59.98 -152.59 81.76
940915 04:00:20.97 4.10 60.59 -151.55 62.52
941023 02:05:42.54 4.00 59.98 -152.68 89.73
941110 22:31:05.37 4.40 60.06 -152.89 97.48
950410 13:44:00.48 4.00 59.79 -151.99 59.19
950504 15:26:58.75 4.10 60.46 -151.44 48.64
950519 07:19:19.35 4.20 61.00 -151.24 67.56
950718 06:59:27.26 4.00 60.05 -152.71 98.29
911006 15:50:23.42 4.20 60.06 -150.58 45.71
950831 13:32:01.79 4.00 59.37 -150.99 41.06
950907 10:33:06.21 4.10 60.29 -151.06 39.71
950911 06:06:04.00 4.10 59.26 -151.83 57.11
951010 15:45:03.57 4.50 59.44 -152.94 82.24
951020 02:49:42.12 4.30 60.04 -152.23 65.06
951030 08:07:13.33 4.70 60.95 -150.19 3.00
960116 00:43:58.54 4.70 60.46 -151.11 45.19
TABLE IV-1
IV-15
TABLE IV-1
JAN 1, 1991-JAN 16, 1996
S2" 30' S2" 30'
S1" 40' S1" 40'
so· so· so· so·
so· oo· so· oo·
59" 10' 59" 10'
Gulf of Alaska
sa· 2o· sa· 2o·
-155" 00154" 1(}'153" 20!152" 30!151" 40-'150" 5()!150" 00!149" 10!148" 20!147" 3(}'146" 40!145" 50!145" 00'
PAEABL07
10/12/96 IV-16
SECTION V
INSTRUMENTATION
A. LOCATION AND TYPE
1. Dam and Spillway Structure Movement
Three lines of survey monuments to monitor horizontal and vertical movement of the dam
and spillway are provided as follows:
a. Upstream face at approximate El. 1120. Five movement monuments SP-1A
through SP-1E. Two control monuments BL-1W and BL-1E.
b. Along crest of dam and spillway. Two control monuments PCM-4 and PCM-2.
Seven movement monuments SP-2A through SP-2G at approximate El. 1189.9.
Four movement monuments on spillway SP-2H through SP-2K. Two at
approximate El. 1195.0 on the non-overflow sections and two at approximate El.
1180.1 on the ogee crest sections.
c. Along downstream Diversion Tunnel Access Road berm at approximate El.
1077. Two control monuments BL-3W and BL-3E. Three movement monuments
SP-3A through SP-3C.
The locations ofthe monuments are shown on Figure E-4. The monuments, except SP-1A
through SP-1E, were initially surveyed at least twice a year for two years and subsequently
once a year.
2. Dam Seismographs
Two seismograph stations are installed at the dam. One station is located on the left
abutment and the other is located on the dam as shown in Figure E-4. The seismograph
stations are maintained and monitored by the University of Alaska at Fairbanks.
The University of Alaska would notify the Project by fax when an earthquake event ofM 5
or greater occurs within a 50-mile radius of the site. Such notification would trigger a
special inspection of the facilities for identification of any changes or damage.
PAEABL08
10/12/96 V-1
3. Dam and Spillway Seepage
No specific instrumentation provisions are in place to measure dam seepage.
The seepage from the spillway foundation drains is measured in a V -notch weir in the
spillway gallery before it is discharged downstream. The seepage is scheduled to be
measured monthly when snow or weather does not preclude access.
4. Power Tunnel
Six piezometers are located in the upper low pressure reach of the power tunnel. Two
piezometers read the reservoir level. Two piezometers read the pressure downstream of the
trashrack. Two piezometers read the differential pressure across the intake control gate.
At the powerhouse, two piezometers are located on the penstock upstream of the spherical
valve and one located downstream to measure the differential pressure across the valve.
Four piezometers are located on the penstock between the turbine inlet and spherical valve.
All piezometers are automatically read through the SCAD A system.
Four drains installed behind the steel liner in the tunnel penstock section monitor ground-
water inflow from the rock surrounding this portion of the tunnel. The drains were
reported partially plugged with calcite and it is unknown from which drain an estimated 40 -
50 gpm is occurring.
B. TIME VS READING GRAPHS OF DATA
The movement of the monuments on the dam and spillway are plotted with respect to time and are
shown in Figures F-1 and F-2. The monument line on the upstream face of the dam at approximate
El. 1120 has not been resurveyed to date, therefore there is no movement data to plot as a function
of time. Surveys are scheduled in the August-September period when the reservoir is normally at
its highest. A special survey of the monument line at EL 1120 should be scheduled when the
reservoir is sufficiently low to permit access to the monuments.
The V-notch weir seepage measurements from the spillway foundation drains is not plotted. Data
from the power tunnel piezometers is not plotted. Data from the tunnel penstock drains is not
collected or plotted.
C. EVALUATION
Overall, the instrumentation data for the dam and spillway structures indicates that the structures
are performing satisfactorily. Movements are quite small and the spillway seepage volumes are
within anticipated values by SWEC. The only anomaly relates to the questionable status of the
tunnel penstock drains that should be cleaned out and restored to operate as intended.
PAEABL08
10/12/96 V-2
With respect to the dam and spillway movement monuments, the greatest variation appears to be
between the positions shown as "ORIG. PLAN DATA" and the survey in the fall of 1992. This
period encompasses the initial fill period when the structures adjusted to the first reservoir loading.
The final report on the initial reservoir filling, Reference 11, concluded that for the period from
October 30, 1990, the start of the reservoir filling, to September 25, 1991, reservoir at El. 1179.5,
that the dam and spillway horizontal and vertical movements were very small without any obvious
trends. Maximum settlement of0.07 feet and maximum lateral movement of0.03 feet downstream
was reported. These movements are exceptionally small.
Surveys initiated in the fall of 1992, indicated some differences from the "ORIG PLAN DATA"
locations and the locations for that survey by the surveyor who has performed all subsequent
instrumentation surveys. The movements of the dam monuments generally reflect normal survey
variance and do not exhibit any trends. The movements of the spillway monuments are similar
except for the backward movement of SP-2K. Surveys of SP-2K since the fall of 1992 indicate
only survey variance. It is concluded that the original location of SP-2K may have been in error.
The greatest recorded movements are related to the monuments along the diversion tunnel access
road at approximate El. 1077. The upstream and downstream movement data essentially show no
movement. The vertical data shows SP-3A down 0.07 feet and SP-3C down 0.14 feet between the
"ORIG PLAN DATA" and the survey the fall of 1992. Subsequent surveys to date only show
survey variance. The horizontal movement (forward and back) shows SP-3C moved back 0.21
feet. Again subsequent surveys show only survey variance. It is concluded that the larger
movements of the SP-3A, SP-3B, and SP-3C monuments between the "ORIG PLAN DATA" and
the survey in the fall of 1992 reflects either an error in the original data location or differences in
the survey baseline. Monument BL-3E shows a cyclic variation in horizontal backward/forward
movement of about 0.04 feet between several surveys. Discussions with the surveyor revealed that
BL-3E is located on a rock cliff and very difficult to access and accurately locate the distance
measuring prism. The variation is small and does not indicate any overall trend. In summary, the
movements on the dam and spillway are small and do not indicate any trends.
Spillway seepage measurements reported a maximum stabilized value of 40 gpm at the maximum
pool level on initial filling of the reservoir. Subsequent recorded data does not indicate flows in
excess of just under 20 gpm for maximum reservoir elevations in the range ofEI. 1171 ±to 1177 ±.
The magnitude of the seepage is within the expected range ofless than 100 gpm by SWEC, the
designer, and there is no reported foundation material being removed. The level of seepage is
considered acceptable. Improvement in the data collection, measurement, and presentation of
results is warranted. The actual foundation drains making water should be recorded as well as the
reservoir elevation at the time of the observation. The flow in the V -notch weir should be plotted
as well as the reservoir elevation for each observation. Lines connecting data points should not be
used for the intermittent records as they could be misleading. Annually, at a reservoir maximum
stage, the flow from each foundation drain should be recorded and plotted with reservoir head.
With respect to the tunnel penstock drains that were reported partially plugged, they should be
unplugged and returned to service as noted earlier. The design of the tunnel steel and concrete
liner was based upon these drains remaining functional. In discussions with Project staff and the
PAEABL08
10/12196 V-3
designer, it became apparent that there was a misunderstanding regarding the need to keep the
drains operating. The Project staff was instructed to verify the functional status of each drain and if
plugged, take steps to open the drains. It is recommended in addition to returning the drains to a
functional condition, that they be observed on a monthly basis for continued operability.
PAEABL08
10/12/96 V-4
SECTION VI
FIELD INSPECTION
The Project facilities were inspected on June 26 and 27, 1996. The weather on both days was
cloudy with occasional light rain. The reservoir was at El. 1113.7 and El. 1114.3 respectively on
each day. Stanley E. Siezkowski; Alaska Energy Authority; Manager, Operations and Maintenance
participated full time during the inspection. Richard Turner, Acting Supervisor and Plant Operator,
representing Homer Electric Association the contract operating agency, was available intermittently
to respond to questions and provide information on the Project.
On June 26, 1996, the powerhouse (exterior and interior), tailrace, power tunnel north adit,
reservoir rim, Nuka Diversion, Middle Fork Diversion, and Upper Battle Creek Diversion were
inspected. A helicopter was used for aerial inspection of the upper facilities. The Nuka Diversion
River Outlet was inspected on the ground. On June 27, 1996, the upper facilities including the
dam, spillway, reservoir outlet works gatehouse, fishwater bypass portal structure, and power
tunnel gatehouse were inspected on the ground.
The dam was observed from the crest and the toe and found to be in an excellent condition.
Concrete on the upstream facing and crest was in good condition and did not exhibit signs of severe
weathering from freeze-thaw attack. The thick concrete crest and parapet did not exhibit any
unusual cracking or signs of structural distress. The upstream concrete facing contains what
appears to be random shrinkage cracking that varies between an estimated 10 to 15 foot spacing
dependent upon the particular face slab. The cracking was most noticeable in the vertical direction.
None of the cracks appeared to be open significantly and no offsets between adjacent sections were
noted. The crest or parapet of the dam did not exhibit observable settlement or
upstream/downstream alignment movement. The plinth and transition joints covered by a surface
mounted conveyor belting waterstop did not indicate any significant opening or offsets. The
exposed waterstop appeared to be in a good condition. The downstream slope outer riprap zone
appeared to be well placed and interlocked. The riprap rock appeared to consist of hard fresh rock
with no indications of unusual weathering. No seepage was noted in the groins or at the toe of the
dam. About 1 to 2 gpm of clear water was noted in a drainage ditch that crosses the lower berm
access road about ISO feet downstream of the left side of the dam. It is not possible to attribute
this flow to dam seepage as the ditch also drains a large area downstream of the left abutment.
The spillway was observed from the crest of the left non-overflow monolith and the lower sill area
of the spillway monoliths. The concrete surfaces of the non-overflow monolith did not exhibit
significant weathering. The concrete surfaces of the overflow monoliths showed more surface
weathering in general and particularly at the construction lift lines. A few vertical shrinkage cracks
were noted in the left non-overflow monolith to the right of the drainage gallery access. The left
monolith of the higher overflow monoliths contained a few notable vertical shrinkage cracks with
calcite surface deposits. The cracks were not seeping during the inspection, however, the reservoir
was below the area of cracking at the time. The most prominent crack was open about 0.025
inches at the downstream face of the lower flip. Some vertical and random cracks in the low
PAEABL09
10112/96 VI-1
overflow monoliths and the joint with the left training wall had been sealed with a mastic. The
mastic sealant appeared well adhered to the concrete and did not exhibit any signs of cracking. The
right abutment training wall did not show any signs of unusual cracking and the five drains at the
base of the wall were weeping to varying degrees. The water feeding the drains appeared to
originate higher up on the abutment from joints in the rock. The water from the drains is believed
to not be reservoir related. The 1 0-inch drain pipe at the base of the deepest section of the high
monolith was dry. The drainage gallery contained several hairline type cracks in the roof and walls
with calcite evidence of past seepage. During the inspection, the cracks were dry. All of the
foundation drains in the gallery were dry during the inspection. There was no notable evidence of
calcite buildup at the tops of the foundation drain pipes. There was no flow in the drainage gallery
V -notch weir.
The reservoir outlet works gatehouse structure was in a good condition. The shaft and valve
chamber were viewed from the top. The shaft showed calcite deposits at a few horizontal
construction joints and the protective coatings on the exposed valve operating cylinders appeared
to be in a good condition. Calcite deposits and moisture were noted on the floor at the base of the
shaft.
The fishwater bypass portal structure was in a good condition. The concrete did not indicate any
evidence of structural cracking or distress. Inside the lower end of the diversion tunnel that has
been shotcreted, there are calcite deposits on the shotcrete surface at cracks and on the penstock
surface. There is a prominent joint that crosses the tunnel at a NE-SW attitude that was emitting
water on both sides of the tunnel. During the inspection, the seepage noted on both sides of the
tunnel walls, was not under high pressure, nor was the volume significant. It was reported that this
joint system seeps considerably when the reservoir is above El. 1170 ±. Sheet metal shields have
been installed in the area of the joint to collect the seepage and reduce spread of the seepage water
within the tunnel. A new gravity flow temporary PVC pipe drain system was installed through the
downstream wall to handle the seepage as it exceeded the capacity of the sump pump. It was
reported that it is planned to replace the temporary PVC pipe system with a more permanent
system. The protective coating on the penstock and its supports was in a good condition and did
not appear to be detrimentally affected by the calcite deposits from the seepage.
The power tunnel gatehouse contains the backup power supply diesel-motor generator set for the
upper facilities. The motor-generator set appeared to be in a good condition. It was not test run
during the inspection. The gatehouse structure was in a good condition with no noted structural
problems. The construction joints in the concrete lined shaft have more seepage than the concrete
lined gatehouse shaft at the reservoir outlet works. The joints where seepage is occurring have
larger and more frequent calcite deposits. The shaft walls below the steel grated operating floor
have considerable deposits of calcite from the shaft wall seepage. The base floor was covered in
seepage and calcite deposits to a depth of 114 to 112 of an inch. Some minor deterioration of the
outer surface of the galvanized piping attached to the wall surface is occurring. Should the
deterioration of the piping continue, it may be necessary at some future date to replace the piping.
The protective coatings on the hydraulic cylinders and cylinder base supports were in a good
condition.
PAEABL09
10/12/96 VI-2
In the left abutment upstream of the dam between the dam and the intake area, there is an
oversteepened earth and rock berm remaining from the construction activities. The berm exhibits a
beaching erosion from the higher reservoir levels that adversely affects the stability of the material.
It was reported that the maintenance budget for removal of the unstable material was approved.
This is a prudent maintenance measure as a slide could possibly deposit debris into the power intake
area.
The left abutment area upstream ofthe dam contains a large deposit of floating debris, mostly
consisting of what appears to be slash from the reservoir clearing and other dead trees, etc., from
areas that were not cleared. It is also planned to remove this debris using a clam shell. It is
unknown how much of this debris may have sunk in the area of the power intake or the reservoir
outlet intake.
The excavated rock surfaces upstream of the power house were substantially rock bolted, covered
with wire mesh, and did not show any signs of distress, excessive seepage, or high groundwater
pressures. The low exposed rock surface to the left ofthe future Unit 3 excavation that was bolted
and covered with mesh, had one small rockfall (2-3 cy) that had occurred. The substructure ofthe
powerhouse that extends from the rock foundation to the generator floor did not exhibit any signs
of structural cracking or distress of significance. The only cracking in the substructure noted was
primarily in the upstream wall at the spiral casing floor level (El. 15.00). The cracking was mostly
associated with the penstock penetrations and other piping penetrations to a height of about 6 feet
above the floor level. The cracking is judged to not be structurally significant. Seepage was
present at most cracks and calcite deposits were on the surface and adjacent piping and equipment.
There was slightly more seepage noted at the upstream wall ofUnit 1. Seepage was of a non-
measurable magnitude. The only other crack noted was vertical about 3 feet in length in the
upstream wall near Unit 2. The crack appeared sealed with calcite deposits. At Unit 1 there were
two puddles on the floor at the joint between the turbine shutoff valve foundation and the general
floor. The seepage was small and appears to evaporate in place. The powerhouse superstructure
was judged to be in a good condition.
The north ad it that provides access to the lower end of the power tunnel was in a satisfactory
condition. The concrete lined section, and the ribbed and shotcrete lined section did not indicate
signs of structural distress although a few cracks were evident. It was not possible to see the
concrete surface of the concrete plug containing the steel penstock access section due to the almost
complete covering of the surface by calcite from seepage. The seepage that in total is non-
measurable seemed to mostly originate in the upper half of the plug at the contact with the tunnel
lining. The floor of the adit was wet and covered with calcite. The short section of penstock with
its ellipsoidal head appeared to be in good condition with no damage currently evident to the
protective coating from the seepage and calcite. A temporary chain link fence and geomembrane
barrier exists at the entrance to prevent freezing of seepage in the winter. It is planned to provide a
permanent insulated wall at the entrance to replace the temporary barrier.
The tailrace excavated into the surrounding tidal marsh is provided with a riprap channel for some
200 feet downstream ofthe powerhouse. The exposed riprap along the sides ofthe channel
PAEABL09
10/12/96 VI-3
appeared to be in a good condition. A submerged rip rap berm exists across the lower end of the
channel. At the right side, the riprap berm appears to have been locally dislodged for about 15 to
20 feet. In addition, in the same area on the right side the natural tideflat deposits have been
eroded from behind the riprap channel side wall for about some 20 to 25 feet. The water in the
tailrace is flowing through the riprap and eroding the material. At the time of the inspection, there
was no evidence that eddy currents from the rip rap berm at the end of the channel were the cause
of the erosion.
Both sides of the reservoir rim were observed from the air. The slopes surrounding the reservoir
have little overburden soil cover and sparse vegetation. Rock slopes varied from an estimated
gentle slopes (20°) to slightly steeper (30°-35°) but were glacially semi-rounded in profile. There
were no areas noted in the slopes that would be of concern regarding the possibility of a significant
slide that could cause a wave that would overtop the dam.
The Nuka Diversion was observed from the air and the ground. It was noted that considerable
water was flowing from both branches of the Nuka Glacier and that the Nuka Pool was full and
flowing out to both the Upper Bradley River and the Nuka River. It was estimated that about 4 to
6 inches of water was flowing over the Nuka Diversion Outlet Structure. The gabions on the crest
at the structure appear to have lost some of the fines from the fill material and have consolidated
due to their own weight and that of the snow load. The gabions at the end of the outlet channel
also appear to have lost fines and consolidated. In addition, the consolidation has resulted in some
sideways distortion toward the channel. It was reported that the deformation has not changed from
that noted last year. The structure in its present condition is performing its intended purpose.
Should the distortion increase in the future and the gabions become completely unstable, it will be
necessary to remediate the problem.
The Middle Fork Diversion was viewed from the air and appeared to be operating as intended. The
diversion drop in the channel, the plug fill, and the downstream berm fill appeared to be in a good
condition. The excavated channel is establishing itself, as would be expected, into a more natural
eroded channel.
The Upper Battle Creek Diversion was observed from the air and considerable flow was noted
entering from the waterfall area on the south side. The dike appeared to be in a good condition.
The Bradley River below the dam was flown and no unusual conditions were noted in this rugged
uninhabited river stretch. The only development is a fish counting camp near the mouth that was
reported occupied intermittently from July through September by fish counting crews of up to
about three people.
The following summary comments address the prescribed field inspection report elements:
PAEABL09
10/12/96 VI-4
A. Settlement
No settlement of the dam, spillway, and other structures was observed.
B. Movement
No evidence of movement of the dam, spillway, and other structures was observed.
C. Erosion
Erosion of fines from gab ion baskets at the Nuka Diversion River Outlet was noted.
Erosion of the oversteepened construction fill along the reservoir side in the vicinity of the power
intake was noted.
Erosion was observed in the unlined Middle Fork Diversion channel.
D. Seepage
No seepage attributable to the dam or spillway was observed.
Seepage was noted in the following structures but all were of a non-measurable magnitude during
the inspection:
• Reservoir Outlet Gatehouse Shaft
• Diversion Tunnel Penstock Section
• Power Tunnel Gatehouse Shaft
• Powerhouse upstream substructure wall at the spiral casing floor level (El. 15.00).
• North Adit tunnel plug.
E. Leakage
No flows noted were of a magnitude or pressure to be classified as a leak.
F. Cracking
Cracking of concrete was observed in most concrete structures. None of the cracking was judged
to be currently structurally significant.
PAEABL09
10/12/96 VI-5
G. Deterioration
No deterioration of a structural significance was noted. Deterioration from corrosive effects of
seepage and calcite deposits at present is limited due to short service life of the project.
H. Geologic Conditions
Geologic conditions observed in the dam and spillway abutments and downstream area, and the
powerhouse excavated slopes are consistent with the description of the geology in Section IV.
I. Foundation Deterioration
No evidence of foundation deterioration was observed.
J. Condition of Spillways and Outlets
The spillway is in an excellent condition and is completely functional.
The reservoir outlet appeared to be in a good condition and is reported functional.
K. Observation of Operation of Representative Number of Spillway Gates and Standby Power
Not applicable as the spillway is ungated.
L. Reservoir Rim Stability
No evidence of reservoir rim instability was observed and no slides were reported.
M. Uplift Pressures in Structures. Foundations. and Abutments
No indications of high or unusual uplift pressures were observed.
N. Functioning ofFoundation Drains and ReliefWells
No foundation drains are provided at the dam. The spillway drains were not functioning during the
inspection due to the low reservoir. The drains are reported functional.
The tunnel drains behind the steel liner in the penstock section ofthe power tunnel, due to calcite
deposits, were reported partially plugged.
0. Other Significant Conditions
The power tunnel was inspected in the spring of 1992, in response to finding concrete, grout, and
rock debris in the turbine pit of Unit 2. The inspection was made to address concern of the
PAEABL09
10/12/96 VI-6
possibility of a damaged or collapsed section of the tunnel. Reference 15 reports on the details and
findings of that inspection. This report will briefly summarize the findings.
• Most seepage inflow occurred in the lower tunnel section downstream of the lower
elbow at the base of the vertical shaft (Sta 177+05±) and upstream of the steel lined
section (Sta 31 +60).
• Seepage inflow ranged from an initial 13.3 cfs to 8.0 cfs for the lower tunnel section.
• Almost no seepage inflow occurred in the upper intake tunnel.
• Very little seepage inflow occurred in the vertical shaft.
• Seepage inflow occurred primarily at construction joints and secondarily at longitudinal
cracks that followed the bedrock joint pattern.
• Zones of moderate to major inflow seepage were noted as:
Station
52+50 to 54+00
57+00 to 61 +00
85+00 to 98+00
102+50 to 111+50
131+50 to 134+50
Seepage Inflow
Moderate
Moderate
Major
Major
Major
• No change was noted in the flow of the penstock drains due to draining the tunnel.
• The tunnel concrete lining as a whole was found to be in a good condition.
• Construction repair patching of the concrete lining generally performed satisfactorily.
• Many of the leakages were high pressure.
• Grout repair patches that had thin feathered out edges peeled off due to poor bonding
from poor surface preparation.
• Nine areas of minor concrete distress damage were noted and are reported by the tunnel
inspectors as caused by the tunnel dewatering. Either water pressures at depth in the
concrete lining or lack of ability of the patch to transmit compression and shear stresses
in weaker concrete zones was reported as the cause of small concrete pop out areas.
Fresh concrete fracture surfaces were reported for the pop out areas.
PAEABL09
10/12/96 VI-7
• The vertical shaft and upper intake tunnel sections were reported in a good condition.
Problems with thin feathered grout patch surfaces were similar to the lower tunnel.
• The power tunnel intake gate seals were reported as only having a very minor amount of
leakage.
As a result of the tunnel inspection the following conclusions and recommendations were reported:
• The tunnel is expected to give satisfactory performance for 1 0 to 15 years.
• It is not anticipated a large number of small isolated liner failures or a large failure will
occur.
• The tunnel is in an operational condition.
• It is preferred to operate the tunnel in a pressurized condition.
• It is expected continued minor grout patch removal will continue.
• Future dewatering and inspection should only occur to evaluate an identified concern
such as a major seismic event that could damage the lining or result in fault
displacement, or an indication of unusual debris in the turbine pits or tailrace.
• Perform future inspection in conjunction with a scheduled major shutdown such as
installation ofUnit 3.
• Areas identified for repair and any new areas should be repaired during the next
inspection.
PAEABL09
10/12/96 VI-8
SECTION VII
STRUCTURAL STABILITY
The structural stability inspection, review, and evaluation of the Project structures for this initial
independent consultant's report focuses on the embankment dam and gravity spillway that are the
principal water retaining structures. This report section will summarize the results of the SWEC
design analyses of these structures and present the independent consultant's evaluation of those
analyses. The primary references used were References 20 and 8 that are extremely well written
and document in detail all information and analyses that are beyond the limited scope of the
summary presented herein. If more detailed information is desired, these references should be
consulted.
A VISUAL OBSERVATIONS
The previous Section VI reported the field inspection visual observations of the Project structures.
The observations did not note any deficiencies related to geologic and foundation conditions,
settlement or movement, drains or uplift pressures, seepage or leakage, erosion, or the general
condition of the concrete faced rockfill dam or concrete gravity spillway that would indicate
problems of stability or structural distress. The concrete faced rockfill dam and the concrete
gravity spillway, are in an excellent physical condition.
B. METHOD OF ANALYSIS
1. Concrete Faced Rockfil/ Dam
The concrete faced rockfill embankment dam was analyzed by SWEC to determine its
factor of safety under various static loading conditions and to predict its potential
deformation under dynamic earthquake loading conditions. The basic structural stability
requirement that must be met by the embankment design is that the reservoir must be
retained under all loading conditions.
For the embankment dam the static conditions of loading computed factors of safety must
be equal to or greater than minimum criteria safety factors currently acceptable as industry
standard practice. The static stability analyses were performed using the LEASE II
computer program that uses the simplified Bishop method for circular surfaces and the
Morgenstern-Price method for non-circular surfaces. The analyses were performed for both
upstream and downstream slopes. Search routines were utilized to identify the selected
most critical potential slip surfaces shown in Figure E-34.
Under dynamic loading conditions, the safety criteria is related to adopted deformation
limits since a safety factor is not relevant to embankment structures particularly when
subjected to very high earthquake accelerations. The dynamic analyses were conducted
using the LEASE II program to determine the static most critical potential slip surfaces and
PAEABLIO
10/12/96 VII-I
the critical or yield acceleration for each. Next the SARMA (Seismic Amplification
Response by Model Analysis) method was utilized to predict potential deformations for the
selected critical potential slip surfaces. The SARMA method first determines resonant
frequencies and response shapes of the embankment for each frequency of the earthquake.
Participation factors calculated for a given potential failure wedge or block describe how
much effect each of the modes of oscillation will have on the potential failure wedge. The
accelerations of the wedge in each mode in response to the earthquake accelerogram are
then determined, and the modes combined resulting in a time-history of the accelerations
that the wedge experiences. The cumulative displacement is then determined by Newmark's
sliding block procedure in which excursions beyond the critical or yield acceleration are
summed to arrive at the total movement or predicted potential deformation.
2. Concrete Gravity Spillway
The concrete gravity spillway was analyzed by SWEC to determine factors of safety and
stresses under static and dynamic loading conditions. The structure was also analyzed to
predict maximum potential movement under dynamic loading conditions.
The static loading conditions included the Case I-Usual (normal maximum reservoir level)
and Case II-Unusual (probable maximum flood) conditions of loading. The dynamic
loading conditions included the Case III -MCE with normal maximum reservoir level and
Case V -MCE with low reservoir level.
Although keys were provided at monolith construction joints, the maximum ogee section of
the spillway was analyzed for static conditions ofloading using a unit-width method,
neglecting any load transfer between monoliths and the abutments, and with a uniform flat
foundation base. Whereas in fact, the foundation base beneath the maximum section of the
ogee spillway is very rugged and in a deep V -shaped twisting channel that slopes down
from the vertical approximately 25 degrees in an upstream direction. The thin right non-
overflow section was keyed into the abutment over its entire length, was anchored to the
abutment, and keyed with the adjacent maximum ogee spillway monolith. As such,
overturning or sliding was deemed not to be critical for the section. The left non-overpour
gravity spillway section was analyzed for the static conditions of loading neglecting any
restraint effects of keys and varying heights of the monoliths.
The short apron of the ogee section was neglected due to its relative flexibility so that the
downstream toe was a hypothetical extension of the downstream face. Since the
deadweight of the apron exceeded any potential uplift in the area, it was neglected. The
static spillway model is shown in Figure E-36.
For any Usual or Unusual condition of loading, if the minimum upstream face stress was
less that the minimum allowable concrete stress, then reinforcing steel was added. The
amount of reinforcing steel was based on working stress methods neglecting all concrete
tensile capability. Shear-friction factors of safety were based on net uncracked areas.
PAEABLIO
10/12/96 VII-2
Since large peak accelerations were expected at the site, the pseudostatic method of analysis
was considered inappropriate for analysis of dynamic stability. Two-dimensional finite
element time history analyses were performed for the ogee sections. The non-overflow
sections were not analyzed for dynamic stresses but were considered adequate by
comparison of cross sections and loadings with the analyzed ogee sections. The
STARDYNE program was used for the two-dimensional linear elastic analyses to determine
stresses and reactions at the base. The STAR program of ST ARDYNE was used for static
analysis of water, ice thrust, and dead weight loads and to perform frequency and model
shape analysis. Dynamic analysis was done by the DYNRE4 program of ST ARDYNE.
The FEM dynamic analysis accounted for hydrodynamic effects of the reservoir water using
the Westergaard added mass approach. To account for the stiffness of the rock foundation,
it was included in the model to a depth equal to the height of the spillway. Three finite
element models were analyzed for spillway ogee sections with bases at El. 1160, El. 1150,
and El. 1124. The models for El. 1160 and El. 1124 are shown in Figures E-42 and E-43.
The SARMA program was used to analyze the spillway for prediction of the maximum
potential permanent deformation under seismic loading conditions. The following
assumptions were made: I. The concrete spillway sections act as an intact failure wedge.
2. The failure plane is the bedrock/concrete interface or a horizontal approximation of
same. 3. All downstream rock restraint was ignored. The critical acceleration of a wedge
section is the horizontal acceleration necessary to initiate sliding and was determined by
statics.
Six spillway cross sections were evaluated in the deformation analyses, including four
spillway ogee sections and two non-overflow sections. The SARMA program requires that
the section be modeled as a symmetrical triangle. To model the spillway sections most
accurately, the model triangle was configured to have the same center of gravity, base
elevation, and area as the spillway section being modeled, as shown in Figures E-52 toE-54
Several loading cases and special conditions were considered in the SARMA deformation
evaluations. In all cases the reservoir was at El. 1180. In Case 1, the static head was
included and the only resisting force considered was the friction between the concrete/rock
interface. The vertical earthquake acceleration, 2/3 of the horizontal acceleration, was used
in the static analysis to determine the critical horizontal acceleration. In Case 2, the inertial
force of the water created by the earthquake was also included by using Zangar's formula.
In Case 3, the inertial force of water was again taken into account as well as 500 psf
cohesion between the concrete/rock interface. The loading case providing the greatest
cumulative displacement was Case 2 and that was analyzed for both peak horizontal ground
accelerations of0.35g and 0.75g.
PAEABLlO
10/12/96 VII-3
C. PROPERTIES OF MATERIALS
1. Concrete Faced Rockfill Dam
PAEABLIO
10112196
.a. Bedrock
Ultimate Bearing Capacity = 40 ksf
Allowable Bearing Capacity = 20 ksf
Specific Gravity = 2.7
b. Concrete Face (12 inches uniformly thick)
Compressive Strength :::::: 3,000 psi
Reinforcement
Horizontal
Vertical
c. Rockfill
#8@ 12
#8@ 12
Properties for the rockfill were not based on actual testing of site materials
for unit weight or strength. The bulk of the rockfill embankment was
constructed of blasted dense angular rock that was extremely well
compacted using a compactive effort higher than is commonly used in
industry practice. The unit weight was based upon the tested specific gravity
of the rock and assumptions relative to porosities in the rockfill. The
strength values were selected based upon published information on large
scale triaxial testing of numerous rockfills worldwide as related to confining
overburden pressures, shown in Figure E-33. The reference "Review of
Shearing Strength ofRockfill" by Thomas M. Leps is widely accepted within
the industry as a reliable source of such data on compacted rockfills.
( 1) Zone 1 (tunnel muck bedding layer -minimum 12 feet wide
Moist Unit Wt.
Sat. Unit Wt.
Friction Angle
125 to 150 pcf, most likely 13 5 pcf
= 138 to 154 pcf, most likely 145 pcf
= 44° to 48°, most appropriate 46°
(2) Zone 2 (central main embankment zone)
Moist Unit Wt.
Sat. Unit Wt.
Friction Angle
:::::: 125 to 150 pcf, most likely 13 5 pcf
:::::: 13 8 to 154 pcf, most likely 14 5 pcf
48° to 53°, most appropriate 48°
VII-4
PAEABLIO
10/12/96
(3) Zone 3 (oversize riprap zone 8 to 20 feet wide)
Same values as Zone 2
(4) Shear Wave Velocity, v. = 700-1000 fps, most likely 800 fps
( 5) Damping Ratio, D .R. = 12% to 20%, most likely 15%
(6) Acceleration Ratio, av!Clb = 0-2/3, most likely tan (0-8)
e = slope angle of sliding surface
2. Concrete Gravity Spillway
a. Bedrock (graywacke)
Ultimate Bearing Capacity =
Allowable Bearing Capacity
Unit Cohesion (C) =
Deformation Modulus =
Poisson's Ratio =
b. Concrete
Unit Weight =
Compressive Strength =
Unit Cohesion (C) =
Static Tensile Strength
Dynamic Tensile Strength =
40 ksf =280 psi
20 ksf 40 psi
160 psi concrete on rock
4 X 106 psi
0.27 static, 0.35 dynamic
145 pcf
3,000 psi
300 psi concrete on concrete
6% compressive strength = 180 psi
150% of static = 270 psi
Minimum Allowable Stress :;;::: WH -f;
W = unit weight water
H = depth below reservoir surface
f; = allowable concrete tensile strength at lift surfaces including
safety factor. Zero at rock/concrete interface.
Modulus of Elasticity
Static =
Dynamic
Poisson's Ratio =
3 X 106 psi
5 X 106 psi
0.2
VII-5
D. UPLIFT ASSUMPTIONS
The uplift pressures were assumed to act over 100 percent of the base area in the analysis of the
concrete gravity spillway are as follows:
• For normal reservoir conditions at concrete lift lines above the foundation, the uplift
varied from full reservoir pressure at the upstream face and varied linearly to zero at the
downstream face.
• At the bedrock/concrete interface the foundation drains were assumed 50 percent
effective. So uplift was assumed to vary linearly from full headwater pressure at the
upstream face to 50 percent of the headwater pressure at the drains and then linearly to
zero at the downstream face.
• For static cracked sections, uplift was 100 percent of headwater pressure for the length
of the crack then varying linearly to zero at the downstream face.
• For PMF conditions the uplift at the upstream face was based on a 50 percent headrise
above the normal headwater pressure. The uplift at the downstream face for the PMF
was assumed negligible.
• Uplift assumptions for dynamic conditions were the same as for normal conditions.
E. PHREATIC SURFACE ASSUMPTIONS
The concrete faced rockfill embankment is sufficiently pervious that for the stability and
deformation analyses the embankment was considered dry and not capable of developing an internal
phreatic surface.
A special study was performed that assumed the embankment had a completely failed concrete face.
Flow nets were drawn on the basis of no concrete face, permeability of the rockfill 10 times the
bedding zone, and the rockfill horizontal permeability 10 times the vertical permeability. The
resulting phreatic surface was found to have none to little effect on the selected critical potential
downstream slip surfaces, see Figure E-35.
F. FACTORS OF SAFETY
1. Concrete Faced Rockfill Dam
The criteria minimum acceptable and calculated factors of safety for the static conditions of
design analysis of the concrete faced rockfill embankment are:
PAEABLIO
10/12/96 VII-6
LOAD CASE
Usual -
Usual -
Unusual-
Maximum Pool (El. 1180)
Tailwater (El. 1 065)
Minimum Pool (El. 1 090)
Tailwater (El. 1065)
PMF Pool
Tail water
(El. 1190)
(El. 1082)
Criteria
Minimum
1.5
1.5
1.5
Calculated
U/S DIS
1.66 1.78
1.66 1.78
1.66 1.78
The established acceptable deformation limits for the dynamic conditions of analysis for the
concrete faced rockfill embankment was a vertical deformation less than one-half the
freeboard or 5 feet and a horizontal deformation less than one-half the width of the bedding
layer zone or 6 feet. The deformations for the selected critical slip surfaces shown in Figure
E-34 determined from the dynamic analyses for the normal case using the most likely input
parameters and the composite Hybrid accelerogram are:
LOAD CASE
Extreme
Extreme
Extreme
PAEABLlO
10112196
(MCE-0.75g)
(DBE-0.375g)
(MTE-0.55g)
SLIP
SURFACE
A
B
c
D
E
F
A
B
c
D
E
F
A
B
c
D
E
F
PREDICTED
DEFORMATIONS (ft.)
Vert. Hor.
2.8 5.0
1.1 2.5
0.3 0.6
1.2 3.2
3.2 5.7
0.8 1.0
0.4 0.7
0.1 0.2
0.0 0.0
0.1 0.3
0.4 0.8
0.0 0.1
1.2 2.2
0.4 1.0
0.1 0.1
0.5 1.2
1.4 2.5
0.3 0.7
VII-7
The maximum predicted deformations are all less than the 5 foot vertical and 6 foot
horizontal criteria. It must also be recognized that the above values do not represent single
surface point offsets but rather represent a bulging and settling distortion value that in
essence is a more gradually varying surface from one location to the other along either the
upstream or downstream slopes of the embankment.
2. Concrete Gravity Spillway
The five stability loading cases that were analyzed for the concrete gravity spillway were:
Case I Normal Reservoir -Usual Condition
1. Normal Max. Reservoir El. 1180
2. Uplift and seepage forces
3. Dead loads
4. Ice at El. 1179.0
Case II Probable Maximum Flood (PMF)-Unusual Condition
1. Max. Reservoir El. 1191
2. Uplift and seepage forces
3. Dead loads
Case III Earthquake -Extreme Condition
Case IV
Case V
PAEABLlO
10112/96
1. Normal Max. Reservoir El. 1180
2. Uplift and seepage forces
3. Dead loads
4. Ice at El. 1179.0
5. Maximum Credible Earthquake (0.75g)
Construction Case-Unusual Condition
1. Reservoir water surface at EI. 1 065
2. Dead loads
3. Construction Condition Earthquake (0.1g) or wind load
Low Reservoir with Earthquake -Extreme Condition
1. Reservoir below El. 1124 (no hydrostatic)
2. Dead loads
3. Maximum Credible Earthquake (0.75g)
VII-8
The stability criteria minimum acceptable factors of safety and maximum allowable stresses used for
the Usual, Unusual, and Extreme cases of design loading analysis of the concrete gravity spillway
are:
Usual Unusual Extreme Unusual Extreme
Case I Case II Case III Case IV Case V
Nor. Res PMF Earthquake Construction Low Res
Stresses:
Concrete (f 'c = 3000 psi)
Safety factor 3.0 2.0 1.0 2.0 1.0
Compression, psi 1000 1500 3000 1500 3000
Tension, psi 60 90 270 90 270
Rock ( 40 ksf = 280 psi ***
Safety factor 2.0 1.5 1.1 1.5 1.1
Compression, psi 140 185 250 185 250
Tension, psi 0 0 * 0 *
Sliding:
Shear -Friction in Concrete
Safety factor 3.0 2.0 1.0 2.0 1.0
(in Concrete and at
Rock/Concrete Interface
On Rock Foundation Joints
and Faults
Safety factor 4.0 3.0 1.2** 3.0 1.2**
* For dynamic analysis by FEM, the tensile stress at the rock/concrete interface shall not
exceed the allowable tensile capacity of the concrete.
* * Safety factors not relevant to SARMA analyses.
*** Safety factors applied to allowable bearing capacity that is one-half the ultimate
bearing capacity.
The concrete gravity spillway was considered stable by SWEC against overturning when the
minimum calculated stress, without uplift, met the minimum allowable stress criteria for concrete
(WH-ft} and when the maximum compressive stresses were less than indicated in the previous table.
The structure was considered stable by SWEC against sliding when the calculated shear friction
factor of safety is greater than 3.0, 2.0, and 1.0 respectively for the Usual, Unusual, and Extreme
cases ofloading.
PAEABLIO
!0/12/96 VII-9
G. STRESS ANALYSIS AND EVALUATION
The static analysis spillway model, stability results, and stress results are shown in Figures E-36
through E-41.
The maximum spillway ogee section static analysis results for the Case I-Usual (normal
reservoir), Case II -Unusual (PMF), and Case IV -Construction (Unusual) are as follows:
Shear-Friction F.S.
Min Calculated
Allowable
Concrete Compression (psi):
Max Calculated
Allowable
Concrete Tension, Including uplift (psi):
Max Calculated
Allowable
Rock Compression (psi):
Max Calculated
Allowable
Case I
Usual
5.2
3
45
1000
3.6*
60
32
140
Case II
Unusual
13.6
2
34
1500
(No Tension)
90
34
185
Case IV
Unusual
61.0
2
48
1500
(No Tension)
90
48
185
* Maximum tensile stress due to uplift without cracking assumed is 3.6 psi. Maximum
tensile stress including iceload and uplift is 7.3 psi, neglecting reinforcement. Section was
reinforced in all tensile zones.
The results indicate that the ice loading in the Case I Usual condition results in tension ( 5 psi) on
the upstream face of the spillway ogee section at EL 1170 and El. 1175. However, stresses for the
Usual condition without ice load or uplift were found to remain compressive. Reinforcing was
added to control cracking due to the ice load, with resulting very low steel stresses (fs = 3.4 ksi).
Since some reinforcing was being added in the upstream face near the crest due to the tension, it
was extended down the upstream face to the base elevation and also over the crest to the point of
inflection to limit thermal and shrinkage cracking and to improve the overall stability of the upper
portion of the ogee.
If the reservoir level were at El. 1178 with the corresponding iceload applied at El. 1177, the static
analysis for the Case I -Usual condition, without uplift, indicates no concrete tension or cracking.
Since ice will occur during winter months when the reservoir is lower, the potential for cracking
due to ice load is minimal.
PAEABLIO
10/12196 VII-10
The Case II and Case IV-Unusual conditions were found to meet the stability criteria without
additional reinforcing. The effective stress, including uplift, for El. 1160 and El. 1165 in the normal
reservoir case was tensile, but these tensile stresses were due to uplift so cracking was not
assumed. With the exception of those levels requiring reinforcing due to ice load (El. 1170 and El.
1175), the resultants for all Usual and Unusual conditions (Case I, II, and IV) are located within
the middle third of the section. No tension was indicated at the rock/concrete interface for any of
the static analyses.
The non-overflow spillway sections in the left abutment were analyzed with bases at El. 1160 and
El. 1180 and were found to be statically stable for all cases. For Cases I & II the stresses at El.
1160 without uplift were compressive at 23 psi to 40 psi. The minimum shear-friction factor of
safety for these cases was in excess of22. Case IV indicated stresses of 1 psi to 72 psi and a
shear-friction factor of safety over 56.
The right non-overflow spillway section was evaluated for seismic stability in the spillway axis
direction using pseudostatically applied accelerations at 0.35 g and 0.75 g. As noted earlier, to
improve the stability of this right non-overflow section, the concrete section was tied back into the
rock abutment using rock bolt anchors.
The maximum ogee section dynamic analysis results for the Case III-Extreme (normal reservoir
level) and Case V -Extreme (low reservoir level) are as follows:
CASE III CASE V
Extreme Extreme
Base at: El. 1124 El. 1150 El. 1160 El. 1124 El. 1150 El. 1160
Concrete Compression (psi)
Max Calculated 155.7 77.9 52.3 165.5 86.3 48.8
Allowable 3000 3000 3000 3000 3000 3000
Concrete Tension (psi)
Max Calculated: w/o uplift 87.3 32.1 45.4 77.5 18.3 22.5
Incl. uplift 111.6 45.1 54.1
Allowable 270 270 270 270 270 270
Rock Compression (psi)
Max Calculated 155.7 77.9 52.3 165.5 86.3 48.8
Allowable 250 250 250 250 250 250
The detailed stress analysis envelope stress value results for the spillway ogee sections for Cases
III and V are presented in Figures E-44 to E-51. All stresses at each of the sections analyzed under
the extreme loading conditions were within the allowable stresses based on 3,000 psi concrete.
Uplift pressures were combined by superposition with the computer analysis results for Case III to
obtain maximum concrete tensions. For Case V the section was analyzed without hydrostatic
PAEABLIO
10/12/96 VII-11
loads but for simplicity included the Westergaard added mass in the seismic analysis. This
approach resulted in slightly conservative seismic stresses that were well within allowable values.
The shear-friction factor of safety was not calculated using the finite element method. Sliding
stability was evaluated by SWEC using the SARMA method of analysis.
The results of the SARMA analysis for the prediction of the maximum potential permanent
deformation under seismic loading indicated that the maximum displacement occurred for Case 2,
with a peak horizontal ground acceleration of0.75g combined with the vertical acceleration. The
potential displacement was found to be 0.5 feet. It should be noted that the inertial force of the
water is not usually considered in such a dynamic analysis and resulted in slight decreases in the
critical acceleration values for all sections. There was no potential movement predicted for the
construction case earthquake ofO.lg and essentially no movement predicted for the DBE of0.35g,
with its displacement being about 1/100 of a foot when no cohesion was assumed. It was
concluded by SWEC that the potential movement of the spillway under earthquake loading will be
small and considering the keyed and fixed-edge plate configuration will likely be zero for the MCE
case.
The amount of intact rock-concrete area needed to force critical wedge accelerations of a least
0.75g and 0.35g was evaluated by SWEC. The required amounts were 2.4% and 0.3% of the
surface area respectively in Case 2 based on a rock shear strength of 1,500 psi. As intact shear-
capable rock is expected to be in excess of 75% under all sections, the actual sliding stability is
expected to be far in excess of that needed to prevent movement. Similarly, with no intact rock,
but using a contact shear strength of 160 psi, the percent bonded area to prevent movement during
the MCE and DBE would be 22 and 2.5 percent, respectively.
The summary ofMCE predicted displacements for Case 2 is presented below:
SARMA RESULTS -CASE 2
Critical MaxGnd Displacement
Base El. Section Acceleration Acceleration ®
1160 Ogee 0.231 0.75g 0.51
1150 Ogee 0.282 0.75g. 0.32
1130 Ogee 0.258 0.75g 0.38
1124 Ogee 0.263 0.75g 0.37
1160 Non-overflow 0.443 0.75g 0.06
1124 Non-overflow 0.334 0.75g 0.20
H. LOADING DIAGRAMS AND SUMMARY OF RESULTS
The loading diagrams and summary of results are shown in Appendix E, Figures E-34 through E-
54.
PAEABLIO
10112/96 VII-12
I. LIQUEFACTION POTENTIAL
The foundation under the compacted rockfill embankment was excavated to bedrock under the
entire footprint of the embankment. Liquefaction of the bedrock foundation or compacted rockfill
embankment is not possible.
PAEABL10
10/12/96 VII-13
SECTION VDI
SPILLWAY ADEQUACY
The basic hydrological studies and the development of the spillway inflow design flood for the
Bradley Lake basin and the Middle Fork Diversion basin were performed by the Alaska District,
Corps ofEngineers in the 1979 ~ 1982 period. Reference 10 presents the results of those very
detailed studies. It was not possible to locate a copy of earlier studies by the Corps but the
information that was available was sufficient to judge the adequacy of the hydrological studies.
The design engineer (SWEC) reviewed the methodology, criteria, and results of the Corps of
Engineers' flood studies and found them to be reasonable and acceptable for design of the Project
spillway facilities. The design engineer, however, did not utilize the hydraulic discharge capacities
of the reservoir low level outlet or the power tunnel to reduce the routed magnitude of the probable
maximum flood (PMF) that was adopted as the inflow design flood.
The Independent Consultant has likewise reviewed the Corps of Engineers hydrology studies and
the site specific probable maximum precipitation study by the National Weather Service, Reference
12. The methodology, criteria, and results were also found to be reasonable and acceptable as a
basis for the Project inflow design flood. The information on the inflow design flood presented
herein is based upon those studies.
A. FLOODSOFRECORD
The gauge, Bradley River, at Bradley Lake Outlet was established in October 1957. The historical
flood of record occurred October 10, 1988, with a peak discharge of8,800 cfs. The five largest
events are:
Date
October 10, 1988
August 10, 1979
September 16, 1982
October 14, 1969
August 4, 1977
Flow (cfs)
8,800
6,020
5,830
5,480
5,120
The recorded peak flows recorded by the USGS since the Project reservoir was filled on September
25, 1991,are:
Date
October 3, 1991
September 15, 1993
August 12, 1994
PAEABLil
10/12/96
Flow (cfs)
512
Ill
140
VIII~l
The annual maximum reservoir levels have been:
Date
October 1, 1991
September 3, 1992
October 11, 1993
October 12, 1994
September 29, 1995
Maximum Elevation
1180.0
1148.8
1176.0
1171.1
1177.5
B. INFLOW DESIGN FLOOD
1. Determination of Probable Maximum Flood
The Probable Maximum Flood (PMF) was based upon developing a watershed model using
the Corps' Streamflow Syntheses and Reservoir Regulation (SSARR) model. The
watershed model was calibrated utilizing selected historical floods to establish hydrologic
characteristics of the basin that would reconstitute the historical floods. The watershed
model was also calibrated against a nearby glacial creek (Wolverine Creek) that had a good
data base of daily streamflow, temperature, and precipitation that greatly improved the
model in regards to these glacial melt aspects. The probable maximum precipitation (PMP)
was determined by the NWS to be a combination of an orographic and non orographic storm
event and the maximum precipitation was determined to occur in the August and September
period that was also consistent with peak streamflow runoff periods. The PMP was applied
to the SSARR model of the Project basin to determine the PMF inflow design flood.
PAEABL11
10/12/96
a. Probable Maximum Precipitation
As noted earlier the PMP was determined in 1961 by a site specific special study of
the Hydro-meteorological Section of the National Weather Service, Reference 12.
The estimates from this report were reviewed by the NWS in June, 1979 and found
to be still valid. The PMP is a combination of orographic and nonorographic rainfall
occurring in August or September. The total 72-hour precipitation for the PMF is
41.0 inches with a maximum 6-hour amount of 11.1 inches. Since the Bradley River
drainage basin is within 10 miles to the lee of the northeast -southwest orientated
mountain range of the Kenai Peninsula, the orographic component was based upon
spillover from the South Coast area lying to the southeast. The inclusion of such
orographic spillover has been found to be appropriate for up to 20 miles beyond
mountain ranges along the West Coast of the United States. The PMP was
distributed in 6-hour periods as prescribed by the NWS as follows:
VIII-2
PAEABL11
10/12/96
Duration (Hours)
6
12
18
24
30
36
42
48
54
60
66
72
Depth (Inches)
11.1
16.8
21.2
25.0
28.0
30.8
33.5
35.5
37.0
38.5
39.8
41.0
Technical Paper 47, Reference 13, was utilized by the Independent Consultant to
estimate the 24 hour PMP for the basin and it was determined at 24.7 inches. This
compares well with the 25 inches from the NWS special study, Reference 12. The
NWS indicated that air temperatures during the August PMP were expected to be
about 2 degrees higher than in September. Therefore, the PMP was forecast for
August to reflect maximum glacial melt.
A 3 day antecedent rainstorm was assumed to occur before the PMP storm, using
the 1 00-year rainfall data from Technical Paper No. 47, Reference 13, and Technical
Paper No. 52, Reference 14. Since the PMF was found to be relatively insensitive
to the lag time between storms, a 48 hour lag time was utilized as a reasonable lag
time period for the PMF derivation.
Snowmelt was handled in the same manner as in the basin flood reconstitutions.
The temperature index method was use to compute melt from the glaciers.
Nonglacial areas were assumed snow free for the August PMP.
b. Watershed Model For Converting Rainfall to Runoff
As noted earlier, the watershed model that was used is the Corps' Streamflow
Syntheses and Reservoir Regulation (SSARR) model. The model was calibrated
using selected historical recorded floods at the outlet ofBradley Lake. These were
three August -September period floods of record on the Bradley River as follows:
Date
10-20 August 1958
8 -17 September 1961
10 -30 September 1966
Recorded Peak Flow (cfs)
4,220
4,890
4,230
VIII-3
In addition, the watershed model was calibrated against glacial runoff from the
Wolverine Glacier to better establish glacial runoff parameters. Schematic diagrams
of the basin models used for reconstitution of flows for the Bradley River at Lake
Outlet and Wolverine Creek are shown in Figure E-27. The reconstituted floods are
shown in Figures E-28 and E-29. Basin characteristics developed and used in the
SSARR model for surface-subsurface split, evapotranspiration index, soil moisture
index, snow cover depletion, melt rate index, and baseflow infiltration index are
shown in Figure E-30.
c. Runoff and Flood Routing Procedures
The separation of flow and losses during the PMF were simulated in the SSARR
model in the same manner as in the basin flood reconstitutions. The Corps' PMF
inflow hydrograph, including the Nuka runoff and Middle Fork Diversion flows, was
adjusted upward to 800 cfs to include 400 cfs additional inflow from the Middle
Fork Diversion.
The PMF was routed through the reservoir to determine the spillway design flood.
Routing used a starting water surface at the uncontrolled ogee spillway crest El.
1180.0. The PMF peak inflow was 31,700 cfs and the routed spillway discharge
was 23,800 cfs at El. 1190.65. The inflow and outflow hydrographs are shown in
Figure E-31.
2. Freeboard Adequacy
The dam is provided with a reinforced concrete crest 2.5 feet in thickness and with a
reinforced concrete parapet wall from El. 1190.0 to El. 1194.0 The parapet is provided
with a wave deflector at the top. Considering the location of the dam in a protected arm of
the reservoir, wave overtopping during a PMF event should only be limited to spray created
by the wave deflector on the parapet wall. The 3.5 feet of residual freeboard above the
PMF reservoir El. 1190.65 is considered adequate.
3. Dam break analysis
Not applicable as spillway capable of adequately passing the PMF.
C. SPILLWAY RATING CURVE
The spillway rating curve is shown in Figure E-31. The theoretical computed discharge
relationships shown has been reasonably verified by model study, Reference 16. In fact, the model
determined only 60 cfs additional flow at the theoretical maximum discharge of 23,800 cfs. The
Independent Consultant has reviewed the spillway rating curve and found it reasonable and
acceptable.
PAEABLI1
10/12/96 VIII-4
SECTION IX
ADEQUACY OF MAINTENANCE AND METHODS OF OPERATION
A. PROCEDURES
The Project is operated and maintained in accordance with the guidelines set forth in the Project
Plant Operation and Maintenance Manual, Reference 9.
The Project is operated solely for the production of hydroelectric power. The normal maximum
reservoir is El. 1180.0 and the normal minimum reservoir pool is El. 1080.0. The Project does not
have a rule curve for operation of the reservoir.
The Project generation is normally operated from the Chugach Dispatch Center. It can also be
operated locally from the Powerhouse Control Room.
The Project operating staff consists of three (3) operators on a rotational 8 days on 6 days off, 10
hours per day basis. Normally there are two (2) operators on site. At the time of the inspection
only one operator was on site. The operators are available to, in case of need, operate the plant
locally, take on-site readings of powerhouse instruments, perform surveillance duties, and perform
general maintenance of facilities. Major maintenance crews, that have on occasion reached about
15 people, are supplied either by Homer Electric or from contracted services.
There are procedures in place for notification of a significant earthquake event and special
inspection as discussed in Section V. There are no formal procedures in place for notification to
the Project of a Tsunami event. In the event of a notification, operators indicated they would
abandon the powerhouse and housing facilities and seek higher ground until there is no longer a
hazard. It would seem prudent that formal notification procedures be implemented.
The construction of an insulated wall barrier at the North Adit is scheduled to prevent ice buildup
from the leakage. This will replace the temporary barrier currently in place.
B. MAINTENANCEOFDAM
The dam, spillway, and outlet works facilities appeared generally well maintained. The facilities are
new and as such maintenance is not a major current effort. As noted earlier, work on stabilizing the
berm upstream of the dam left abutment and removal of floating debris is scheduled. The
installation of a permanent drain for the reservoir outlet tunnel is also scheduled. The only
maintenance item that needs constant attention should be the removal of calcite deposits in the
reservoir outlet works gateshaft facilities to prevent deterioration of equipment and piping.
PAEABL12
10/12/96 IX-I
C. MAINTENANCE OFF ACILITIES
The other facilities also appeared generally well maintained. A new project makes maintenance
easy, but in this harsh environment the honeymoon will not last long. The wood type construction
buildings are beginning to show signs of attack from the weather and will soon need repairs and
treatment of the siding.
As with the calcite deposits in the reservoir outlet works gateshaft, the power tunnel gateshaft has
similar needs. Removal and control of the calcite deposits to prevent damage to equipment and
piping will require constant attention.
It is understood that studies are underway as the best way to address the erosion behind the riprap
that is occurring at the downstream end of the tailrace. Since it is in a wetland area, these
considerations must be included in any repair scenarios.
The backup power supply source for operation of the upper facilities is tested on a monthly basis by
running the diesel-generator set and testing of the transfer scheme for auto transfer in the event of
loss of primary power. The backup power source for the lower facilities is run on a weekly basis
and full load tested monthly. These procedures are considered adequate.
During the inspection, a new road was being constructed to replace a construction road that was
removed to the construction air strip. This will provide an air strip for transportation of crews and
equipment that is believed will be more dependable from an operational basis.
D. SURVEILLANCE
Surveillance of project facilities is formally scheduled on work order forms that are issued as a
function of the formal preventative maintenance program. On a monthly basis, when the access
road is open, the dam, spillway, spillway gallery and drains, outlet works, outlet works gatehouse,
and power tunnel gatehouse are inspected. The Nuka Diversion, Middle Fork Diversion, and
Upper Battle Creek Diversion are inspected as a minimum semi annually. The powerhouse and
tailrace are formally inspected annually.
In reality, when the access road is open, most facilities are casually inspected as operating staff
performs nearly weekly maintenance or checking of equipment nearby. However, the access road
is normally not open from November through April. It is recommended that during this period a
monthly fly over of the upper facilities be performed as operating staff are transported to and from
the Project. The objective of the fly over is to note any unusual conditions that may develop so that
corrective action, if needed, can be initiated in a timely manner.
PAEABLI2
10/12/96 IX-2
E. EVALUATION
The Project has a good system of operation and maintenance procedures in place with the
preventative maintenance program and the Plant Operation and Maintenance Manual. The
operation and maintenance procedures are considered adequate.
Maintenance of the dam and other facilities is generally good. Certain features were noted as
needing specific maintenance attention and these are outlined in Section XI. As the project ages,
maintenance needs will increase. The need for additional permanent maintenance staff or contract
services will become necessary in order to not compromise the quality of the facilities.
Surveillance of the dam and other facilities is considered adequate with initiation of monthly flights
for inspection during periods when the access road is closed.
PAEABL12
10/!2196 IX-3
SECTION X
CONCLUSIONS
A ASSESSMENT OF DAMS AND OTHER WATER RETAINING STRUCTURES
1. Field Inspection
• The concrete faced rockfill dam and concrete gravity spillway are in an excellent
condition and functional for their intended purpose.
• No deficiencies were noted related to geologic foundation conditions,
settlement, movement, drains or uplift pressures, seepage or leakage, erosion, or
the general condition ofthe concrete faced rockfill dam and concrete gravity
spillway.
• Cracking of concrete noted during the inspection was judged currently not
structurally significant.
• No conditions were observed around the reservoir rim that are considered to
present a slide hazard sufficient to be a hazard to the dam.
2. Stability Analysis
PAEABL13
10/12/96
• Foundations were judged adequate for the concrete faced rockfill dam and
concrete gravity spillway.
• Special drainage provisions for the concrete faced rockfill dam are not necessary
for stability.
• Foundations drains provided for the concrete gravity spillway are necessary to
maintain uplift pressure reduction for stability.
• The seismicity investigations were comprehensive and the basis for selection of
the Maximum Credible Earthquake and Design Basis Earthquake is reasonable
and acceptable for the stability evaluations.
• Use of a Hybrid accelerogram for stability analyses to represent site rock
conditions and the high frequency peaks is considered logical and acceptable.
• The consideration of a reservoir Seiche and its effect on the stability of the
concrete faced rockfill dam parapet is appropriate and acceptable.
X-1
• The methods of analysis and the analyses employed for the structural stability
analyses of the concrete faced rockfill dam and concrete gravity spillway were
comprehensive, appropriate, and acceptable.
• The assumptions and determinations of the properties of materials, uplift
conditions, and phreatic surfaces for the concrete faced rockfill dam and the
concrete gravity spillway are considered reasonable, appropriately conservative,
and acceptable.
• The factors of safety adopted for the minimum criteria for the concrete faced
rockfill dam and the concrete gravity spillway stability are consistent with the
general standard practice of the dam engineering industry and acceptable.
• The computed factors of safety for stability of the concrete faced rockfill dam
for the Usual and Unusual loading conditions exceeded the minimum criteria and
therefore are acceptable.
• The deformation limit criteria for the deformation of the concrete faced rockfill
dam are reasonable and acceptable.
• The predicted deformation of the concrete faced rockfill dam for the Extreme
(Maximum Credible, Design Basis, and Mega Thrust) earthquake loadings were
all less than the allowable deformation limits and therefore are considered
acceptable.
3. Stress Evaluation
PAEABLl3
10/12/96
• The factors of safety for the concrete gravity spillway of 3. 0, 2. 0, and 1. 0 for
determination of minimum acceptable stresses for the Usual, Unusual, and
Extreme loading conditions are consistent with the general standard of practice
of the dam engineering industry and acceptable.
• The computed factor of safety for stability of the concrete gravity spillway for
the Usual and Unusual loading conditions exceeded the criteria and therefore are
acceptable.
• The addition of reinforcing steel in the upstream face and crest of the concrete
gravity ogee spillway to resist potential tensile stresses and to limit thermal and
shrinkage cracking is a conservative measure.
X-2
• The computed shear-friction factors of safety for the concrete gravity spillway
for the Usual and Unusual conditions ofloading exceeded the minimum
allowable factors and therefore are acceptable.
• The computed compressive and tensile stresses in the concrete and the
compressive stresses in the foundation for the Extreme loading conditions of the
concrete gravity spillway did not exceed the minimum allowable stresses and
therefore are acceptable.
• The SARMA analysis of the concrete gravity spillway for the prediction of
sliding stability deformation and the associated assumptions are extremely
conservative. It is believed that when all factors of foundation shape, roughness,
and strength of concrete and rock at the interface are reasonably considered, that
the predicted movement for the Extreme loading condition will be zero.
4. Spillway Adequacy
PAEABL13
10/12/96
• The use of the Corps' SSARR model for the development of the Inflow Design
Flood is acceptable.
• The use of the Probable Maximum Precipitation developed by the U.S. Weather
Bureau's special study remains consistent with currently published data and is
acceptable.
• The procedures used for modeling basin characteristics was reasonable and
acceptable.
• The selection of an August PMP and assumption of no snow melt except on
glaciated areas is reasonable and acceptable.
• The spillway rating curve that was confirmed by model study is acceptable.
• The routing of the PMF Inflow Design Flood of 31,700 cfs resulting in a
spillway discharge of23,800 cfs at El. 9190.65 is acceptable.
• The 3. 5 feet of residual freeboard during the peak of the PMF in conjunction
with the wave deflector parapet wall is considered adequate.
• The spillway is capable of adequately passing the PMF.
X-3
B. ADEQUACY OF INSTRUMENTATION AND MONITORING OF INSTRUMENTATION
• The three lines of movement monuments on the concrete faced rockfill dam and
concrete gravity spillway are adequate to monitor movements of the structures.
• It would be desirable to conduct a survey of the concrete faced rockfill dam monuments
on the upstream face at El. 1120 at least once every five years to monitor deformation
of the concrete face.
• The installation of seismographs on the dam and its abutment is appropriate for a
project located in an area of known high seismicity.
• It is unfortunate that there is no specific installation to directly collect and measure dam
seepage or leakage. It would be desirable at least once each year during a dry period to
measure as reasonably as possible the dam seepage and leakage at the stream gauge
downstream of the dam.
• It would be desirable during the monthly inspection of the spillway gallery to note the
flow from the individual foundation drains and the reservoir level at the time of the
inspection.
• It would be desirable to measure the flow from individual foundation drains at least
once each year when the reservoir is at its maximum stage for the year.
• It would be desirable to plot the V -notch weir flow measurements and reservoir level
with respect to time.
• The four penstock drains need to be rehabilitated by cleaning out the calcite deposits to
permit monitoring of the effectiveness of the individual drains to control external
pressures around the steel lined section of the power tunnel.
C. ADEQUACYOFNUUNTENANCEANDSURVE~LANCE
• The new Project is generally maintained in a good condition.
• The scheduled surveillance of the Project facilities is generally adequate except for the
dam and spillway during the winter when the access road is blocked by snow.
• It would be desirable in the winter at least once a month to fly over and visually inspect
conditions at the dam and spillway.
• The planned maintenance consisting of removal of reservoir floating debris, removal of
the unstable berm above the power intake area, installation of a permanent tunnel drain
PAEABL13
l0/12/96 X-4
in the outlet works, and installation of an insulated bulkhead in the North Adit is
appropriate.
D. ADEQUACY OF PROJECT OPERATION
The Project appears to be operated for its intended purpose consistent with the operation and
maintenance manuals and procedures. No deficiencies were noted.
E. ADEQUACY OF OPERATION OF SPILLWAY GATES AND STANDBY POWER
Not applicable as the spillway is ungated.
PAEABLI3
10/12196 X-5
SECTION XI
RECOMMENDATIONS
A. CORRECTIVE MEASURES REQUIRED FOR STRUCTURES
No deficiencies were noted, therefore there are no corrective measures required.
B. CORRECTIVE MEASURES REQUIRED FOR THE MAINTENANCE OR
SURVE~LANCEPROCEDURES
1. Survey the movement monuments on the upstream face of the dam at El. 1120 at least
once every five years when the reservoir, through normal operation, permits access to
the monuments.
2. At least once a year, during a dry period to reduce the effect of local surface runoff,
measure the dam seepage and leakage at the gauge downstream of the dam with
computed adjustment for any flows required for stream releases.
3. During the monthly inspection of the spillway gallery foundation drains, record which
individual drains have visible water in them or are flowing. Also record reservoir level
at the time of the inspection.
4. At least once a year when the reservoir level is at its maximum for the year, measure and
record the flow from the spillway gallery individual foundation drains and record the
reservoir level at the time.
5. Plot the spillway gallery V-notch weir flow measurements and reservoir level with
respect to time.
6. Visually monitor monthly and measure once a year the flow from the four individual
penstock drains. Record the observations and flow measurements for evaluation of
drain system effectiveness.
7. Monthly, fly over and observe conditions at the dam and spillway during winter periods
when road access is not possible.
C. CORRECTIVE MEASURES REQUIRED FOR THE METHODS OF OPERATION OF THE
PROJECT WORKS
No deficiencies were noted, therefore there are no corrective measures required.
PAEABL14
10/12/96 XI-1
D. SCHEDULE TO CARRY OUT EACH CORRECTIVE MEASURE
Corrective
Measure
B. I.
B.2.
B.3.
B.4.
B.S.
B.6.
B.7.
Schedule
Once each five years, reservoir level permitting
Annually
Monthly, when access permits
Annually
Monthly, when readings are obtained
Monthly observe flow. Annually measure flow.
Monthly, when road access is not possible
E. ANY NEW OR ADDITIONAL MONITORING INSTRUMENTS. PERIODIC
OBSERVATIONS. OR OTHER METHODS OF MONITORING PROJECT WORKS OR
CONDITIONS
Recommendations relative to these issues were made in Subsection B.
PAEABLI4
10112/96 XI-2
SECTION Xll
CERTIFICATION
A. Statement of Independence
The initial independent consultant's inspection of the Bradley Lake Hydroelectric Project, FERC
Project No.8221-AK, and this report were made in compliance with Part 12 of the Federal Energy
Regulatory Commission rules under Title 18 of the Code of Federal Regulations. All conclusions
and recommendations in this report were made independently of the Licensee, its employees, and
its representatives.
B. List ofParticipants
The inspection was performed and the technical material and data in this report were prepared by:
Donald E. Bowes, P.E., Civil Engineer
C. Signature oflndependent Consultant
PAEABL15
10/12/96
PAEABL23
10/12/96
APPENDIX A
FERC LETTER APPROVING CONSULTANT
r:: .. . . ' ''fl f? r-....
FEDERAL ENERGY REGULATORY COMMISSibW) \[ I; •!--: '. \~! lt ! ~ I
WASHINGTON.DC.20426 w :;:,4:;~_;~ i__~J
Mr. Stan Sieczkowski
Manager, Maintenance and Operations
Alaska Energy Authority
480 West tudor
Anchorage, Alaska 99503
Dear Mr. Sieczkowski:
'APR 19 199tf
and Exporl Author it\.·
Project No. 8221
Bradley Lake-NATDAM # AK83016
Alaska Energy Authority
I
By letter dated April 10, 1996, you proposed Mr. Donald E. Bowes, P.E. as the
independent consultant to be responsible for the first Part 12 safety inspection of the Bradley
Lake project. Mr. Bowes' resume confirms that he meets the Commission's independent
consultant qualifications specified in Section 12.3l(a) of the regulations. Mr. Bowes is
therefore approved as the independent consultant for this inspection. In accordance with
Section 12, Subpart D, the approved independent consultant must either personally inspect
the project or be present during the inspection to supervise those individuals that conduct the
inspection. You are also reminded to instruct your consultant that should any condition be
discovered that requires emergency corrective measures, he must immediately notify you,
since you are required to submit a report to the Regional Director in accordance with
Section 12.36.
Three copies of the inspection report must be filed with the Portland Regional
Director by December 31, 1996. The consultant's report must be formatted in accordance
with the enclosed outline. In addition, your consultant should be prepared to submit, if
requested, diskettes containing computer programs with documentation and input files for any
of the computer analyses used to reach the conclusions in his report.
You are reminded that not later than 60 days after the report of the independent
consultant is filed with the Regional Director, you must submit to the Regional Director three
copies of a plan and schedule for designing and carrying out any proposed corrective
measures.
Sincerely,
?on~ ~DITec~r
Division of Dam Safety and Inspections
Enclosure
PAEABL23
10/12196
APPENDIX B
CONSULTANT'S SCOPE OF WORK
SPECIFIC SCOPE OF SERVICES
In accordance with the procedures in.the Code of Federal Regulations, Title 18, Part 12, Subpart D, the
Bradley Lake Hydroelectric Project works, excluding transmission and transformation facilities and generating
equipment, must be periodically inspected and evaluated by or under the responsibility and direction of an
approved independent consultant, who may be a member of a consulting firm, to identify any actual or
potential deficiencies, whether in the condition of those project works or in the quality or adequacy of project
maintenance, surveillance, or methods of operation, that might endanger public safety.
SPECIFIC INSPECTION REQUIREMENTS
(1} SCOPE OF INSPECTION. The inspection by the independent consultant shall include:
(a) Due consideration of all relevant reports on the safety of the development made by or written
under the direction of Federal or State agencies, submitted under Commission regulations, or
made by other consultants;
(b) Physical field inspection of the project works and review and assessment of all relevant dat.
concerning:
(i) Settlement;
(ii) Movement;
(iii) Erosion;
(iv) Seepage;
(v) Leakage;
(vi) Cracking;
(vii) Deterioration
(viii) Seismicity;
(ix) Internal stress and hydrostatic pressures in project structures or their foundations or
abutments;
(x) Functioning of foundation drains and relief wells;
(xi) Stability of critical slopes adjacent to a reservoir or project works; and
(xii) Regional and site geological conditions; and
(c) Specific evaluation of:
(i) Adequacy of spillways;
(ii) Effects of overtopping of non-overflow structures;
(iii) Structural adequacy and stability of structures under all credible loading conditions;
(iv) Relevant hydrological data accumulated since the project was constructed or last
inspected under this subpart;
(v) History of the performance of the project works through analysis of data fran
monitoring instruments; and
{vi) Quality and adequacy of maintenance, surveillance, and methods of project operations
for the protection of public safety.
(:L) EVALUATION OF SPILLWAY ADEQUACY. The adequacy of any spillway must be evaluated by
considering hazard potential which would result from failure of the project works during flood flows.
(a) If structural failure would present a hazard to human life or cause significant property damage,
the independent consultant must evaluate the ability of project works to withstand the loading
or overtopping which may occur from a flood up to the probable maximum flood or the capacity
of spillways to prevent the reservoir from rising to an elevation that would endanger the project
works.
(b) If structural failure would not present a hazard to human life or cause significant property
damage, spillway adequacy may be evaluated by means of a design flood of lesser magnitude
than the probable maximum flood, if the report of the independent consultant provides a
detailed explanation of the basis for the finding that structural failure would not present a
hazard to human life or cause significant property damage.
(3) EMERGENCY CORRECTIVE MEASURES
If, in the course of the inspection, the independent consultant discovers any conditions for which
emergency corrective measures are advisable, the independent consultant must immediately notify
the Energy Authority.
(4) REPORT OF THE INDEPENDENT CONSULTANT
{a) General requirement. The independent consultant shall complete his inspection of the project
during July 1996. Following inspection of the Bradley Lake Project, the independent
consultant must prepare a report for the Authority. A draft report shall be completed by August
31, 1996. Following review by the Authority, to be completed by September 15, 1996 a final
report, including the independent consultants revisions made in response to Authority review
comments will be prepared. The original signed report and fifteen copies shall be provided to
the Authority by October 15, 1996. The report must conform to the provisions of 18 CFR, Part
12. Subpart D and be satisfactory to the authorized FERC representative. An outline prepared
by FERC of the required report is attached to this scope as Attachment A.
(b) General information in the initial report. (1) The report prepared by the independent
consultant must contain.
(i) A description of the project development;
(ii) A map of the region indicating the location of the project development;
(iii) Plans, elevations, and sections of the principal project works;
(iv) A summary of the design assumptions, design analyses, spillway design flood, and the
factors of safety used to evaluate the structural adequacy and stability of the project
works; and
(v) A summary of the geological conditions that may affect the safety of the project works.
(c) Information required for all reports. Any report of an independent consultant filed under this
subpart must contain the information specified in this paragraph.
(1) Monitoring Information. The report must contain monitoring information that includes graphs
depicting data compiled from any existing critical or representative monitoring instruments tha
measure the behavior, movement, deflection, or loading of project works or from which the
stability, performance, or functioning of the structures may be determined.
(i) Monitoring data plotted on graphs must be presented in a manner that will facilitate
identification and analysis of trends. The data may be summarized to facilitate
graphical representation.
(ii) Plan and sectional drawings of project structures sufficient to show the location of all
critical or representative existing monitoring instruments must be included. If these
drawings have been included in a previous report prepared and filed by an independent
consultant, they may be incorporated by specific reference to that earlier report.
(2) Analyses. The report must:
(i) Analyze the safety of the project works and the maintenance and methods of operation
of the development fully in light of the independent consultant's reviews, field
inspections, assessment, and evaluations.
(ii) Identify any changes in the information and analyses required by paragraph (b) of this
section that have occurred since the last report prepared by an independent consultant
pursuant to 18 CFR, Part 12 and analyze the implications of those changes.
(iii) Analyze the adequacy of existing monitoring instruments, periodic observation
programs, and other methods of monitoring project works and conditions effecting the
safety of the project or project works with respect to the development.
(3) Recommendations. Based on the independent consultant's field observations and evaluation~
of the project works and the maintenance, surveillance, and methods of operation of the
development, the report must contain the independent consultant's recommendations on:
(i) Any corrective measures necessary for the structures or for the maintenance or
surveillance procedures or methods of operation of the project works;
(ii) A reasonable time to carry out each corrective measures; and
(iii) Any new or additional monitoring instruments, periodic observations, or other methods
of monitoring project works or conditions that may be required.
(4) Dissenting views. If the inspection and report is conducted and prepared by more than one
independent consultant, the report must clearly indicate any dissenting views concerning the
analyses or recommendations of the report that might be held by any individual consultant.
(5) List of participants. The report must identify all professional personnel who have participated
in the inspection of the project or in preparation of the report and the independent consultant
who directed those activities.
(6) Statement of independence. The independent consultant must declare that all conclusions
and recommendations in the report are made independently of the licensee, its employees,
and its representatives.
(7) Signature. The report must be signed by the independent consultant.
PAEABL24
10/12/96
APPENDIX C
CONSULTANT'S RESUME
DONALD E. BOWES, P .E.
CONSULTING ENGINEER
16225 S.E. 29th Street
Bellevue, WA 98008
Phone: (206) 562-6093
Fax: (206) 641-3747
SPECIALIZED EXPERIENCE:
Mr. Bowes has over 35 years of ·broad civil engineering experience in water resources
engineering. His experience includes planning, licensing, design, construction, operation, safety
evaluations, and rehabilitation of multipurpose projects involving dams, conventional and
pumped storage hydroelectric facilities, water supply facilities, flood control facilities, and
irrigation facilities. His experience includes all types of embankment and concrete dams varying
in heights to 770 feet (235 m) and hydroelectric projects up to 2,000 MW and 1,300 feet (396 m)
of head.
Technical experience encompasses hydrology, hydraulics, geology, soil mechanics, rock
mechanics, stability and stress analysis, dam design, hydraulic structures design, construction
contract documents, construction engineering management, operation evaluations, and dam
safety inspections and evaluations.
EDUCATION I SPECIAL TRAINING:
Northeastern University, B.S. Civil Engineering, 1959
University of California, Advanced Soil Mechanics, 1966-1967
California Water Resources, Advanced Seepage and Drainage, 1967
Sacramento State College, Graduate Soil Mechanics Program, 1969 -1970
California Water Resources, Advanced Soils Mechanics Testing, 1968
Corps of Engineers -HEC, Flood Hydrograph Analysis. 1969
Pepperdine University, Construction Contract Litigation, 1980
University of Wisconsin. Pumped Storage Development, 1988
University of Missouri-Rolla, Seismic Design and Analysis of Embankment Dams, 1989
University of Washington, Rock Mechanics, 1991
Bureau of Reclamation, Safety Evaluation Existing Dams (SEED}, 1993
University of California, Advances in Earthquake Engineering Practice, 1994
PROFESSIONAL REGISTRATION:
California -14191
Washington -13284
Alaska -3273
Oregon-14110
MRES0196
Colorado-26180
Wyoming -1778
Utah-719809112
Arizona -23109
I
PROFESSIONAL SOCIETIES:
United States Committee on Large Dams
• Life member, member since 1965
• President, 1991-1992
• Board of Directors; 1987-1992
• Committee on Materials for Embankment Dams
-Member since 1982
-Chairman 1986-1989
• Committee on Dam Safety
-Member since 1993
International Commission on Large Dams
• Committee on Fill Dams; United States Representative 1986 -1989
• 16th Congress, Question 61 Session Officer; "Impervious Elements Other
Than Clay Cores."
• 18th Congress, Question 68 Chairman; "Safety Assessment and Improvement
of Existing Dams."
American Society of Civil Engineers
• Member~nce1959
• Committee on Hydraulic Structures
-Member 1976 -1983
-Chairman 1978 and 1982.
Association of State Dam Safety Officials, Member
American Concrete Institute, Member
International Society of Soil Mechanics, Member
EMPLOYMENT HISTORY
July 1993 to Present
President: Donald E. Bowes, P.E., Inc.
Bellevue, WA
March 1971-July 1993
R. W. Beck, Seattle, WA
Principal Engineer to Partner
July 1959-March 1971
California Department of Water Resources
Civil Engineer to Senior Engineer
MRES0196 2
EXPERIENCE SUMMARY:
July 1993 to Present
President: Donald E. Bowes, P.E. , Inc.
Bellevue, WA
Since July 1993, the following independent consulting services have been performed:
16 MW South Fork Tolt River Project-Consultation on design and construction engineering
of a S-mile-long 68-inch steel pipeline/penstock and 986-foot head 16 MW surface power
plant.
Green River Headworks Project -450 MGD water supply project involving a diversion dam;
river intake; and fish ladder, screening, and bypass facilities. Design and constructability
consultation on raising of an existing gravity dam, new river intake, and new fish handling
facilities.
Portugues Dam Flood Control Project -220-foot-high arch dam, performed review of
contract documents and consultation on design/constructability aspects of the project.
15 MW Terror Lake Project-193-foot-high concrete faced rockfill dam, 5.1-mile-long 11-foot-
diameter unlined power tunnel, 3,1 00-foot-long 96 to 63 inch steel penstock to a 1,136-
foot head 15 MW surface power plant. Design consultation on retro-fit installation of a
de-sanding flushing system for the power tunnel.
1.9 MW Barber Project -Retained to perform geotechnical investigations of 28-foot-high
homogenous embankment dam and alluvial foundation, embankment dam stability
evaluation, seismicity evaluation, earthquake liquefaction evaluation, and wood timber
crib dam spillway hydraulic and stability evaluation.
Hog Lake Dam -Design consultation on rehabilitation alternatives to increase spillway
capacity for the 25-foot-high embankment dam.
Pyramid Dam Project-Independent safety adequacy evaluation of the 400-foot-high central
core rockfill embankment dam. The 171,200 acre-foot reservoir forms the upper
reservoir for the 1,250 MW Castaic Pumped Storage Project.
1,250 MW Castaic Pumped Storage Project -Independent safety adequacy evaluation of
the project involving a 7.2-mile-long 30-foot-diameter unreinforced concrete lined power
tunnel, six 13.5-foot-diameter surface steel penstocks, 1,078-foot head 1,250 MW
surface pumped storage plant, and a lower reservoir impounded by the 1 07 -foot-high
Elderberry Forebay earth/rockfill dam.
280 MW Devils Canyon Project -Independent safety adequacy evaluation of the 249-foot-
high Cedar Springs earth/rockfill dam forming the upper reservoir for the 3.8 mile long
13.0-foot-diameter unreinforced concrete lined power tunnel and twin 6,750-foot-long 9.5
foot-diameter steel penstocks to the 1 ,430-foot head 280 MW surface power plant.
MRES0196 3
6 MW Blue Lake Project -Independent safety adequacy evaluation of the 170-foot-high arch
dam, 7,500-foot-long 11.5-foot-diameter and 10-foot modified horseshoe unlined power
tunnel, and 323-foot head 6 MW surface power plant.
22.5 MW Swan Lake Project-Independent safety adequacy evaluation of the 174-foot-high
arch dam, 2,300 foot-long 11-foot-diameter concrete lined power tunnel, and 304-foot
head 22.5 MW surface power plant.
10.1 MW Pinnacles Project-Consultation on stability and structural adequacy of the 143.5-
foot-high Talbott arch dam and the 133-foot-high Townes arch dam.
7.5 MW Hancock Creek Project-Technical and economic feasibility evaluation of the 7,830-
foot-long 45 to 40 inch buried steel penstock and 1,136-foot head 7.5 MW surface power
plant.
7.5 MW Calligan Creek Project-Technical and economic feasibility evaluation of the 6,450-
foot-long 42 to 40 inch buried steel penstock and 1,041-foot head 7.5 MW surface power
plant. Follow-up technical design consultation on alternative project arrangement to
reduce capitalized cost.
3. 1 MW Chilkoot Project -Performed site reconnaissance and technical consultation on the
project consisting of an upper reservoir embankment dam, 30-inch diameter 5,600-foot-
long surface steel penstock and 2,000-foot head 3.1 MW surface power plant.
Consultation focused on layout and design of the 41-foot-high concrete or steel-faced
rockfill upper reservoir storage dam that is to be constructed in a remote area with no
road access ..
1.040 MW Boundary Project-Independent safety adequacy evaluation of the project with a
340-foot-high arch dam, two radial gated spillways, seven gated spillway sluices, six 26-
foot diameter concrete lined penstocks to an underground power plant with a capacity of
1,040MW.
30 MW Cedar Falls Project -Participated as a member of special consulting team to
evaluate effects of high reservoir stages on stability of reservoir rim comprised of glacial
outwash materials and the safety of long term operation of the reservoir at the high
stages. The project involves a 215-foot-high gravity dam, 1,500-foot-long 11-foot-
diameter concrete lined tunnel, two 78-inch steel penstocks 7,500 feet long to a 620-foot
head 30 MW surface power plant.
6 MW Blue Lake Project -Preparation of designs, contract documents, and construction
engineering consultation for rehabilitation of the power tunnel intake facilities involving
repair of the fixed wheel gate rail system, replacement of fixed wheel gate seals and
hoist cables, and installation of a hydraulic operated by-pass gate.
MRESOI96 4
September 1990-July 1993
Partner; R. W. Beck, Seattle, WA
Western Engineering Division, Director of Operations
General management of facilities, human resources, engineering product production, and
financial performance of the division consisting of 140 engineering and environmental staff.
Division engineering and environmental services included water resources, municipal
water/waste water, solid waste, hazardous waste, electrical generation and transmission, and
construction management.
March 1971 -September 1990
Partner; R. W. Beck, Seattle, WA
Western Engineering Division, Principal Engineer to Partner
Engineering and management responsibilities ranged over this period from design engineer,
project engineer, project manager, to partner and manager of the firm's water resources
engineering services. The services performed involved feasibility, licensing, design,
construction, operation, and rehabilitation of water supply, flood control, and hydroelectric
projects. Representative projects include: • Manitou Springs Dam -135-foot-high water supply
zoned embankment dam • 2,000 MW AntHon Lake Pumped Storage Project-two 265-foot-high
zoned embankment dams and 1,300-foot head 2,000 MW underground powerhouse • 2.1 MW
Lake Silvis Power Plant-327-foot head surface power plant • 224 MW Chelan Falls Project-
200-foot-high zoned embankment dam • Wyoming Water Supply Project -three zoned
embankment dams 120, 195, and 275 feet in height • 20 MW Thomas Bay Project -_gravity
dam, 5,450 feet of tunnels, 590-foot head surface power plant • 12-MW Virginia Lake Project-
130-foot-high rockfill dam, surface power plant • 400 MW Clavey Wards Ferry Project -400-
foot-high earth/rockfill dam, two concrete dams, 5 miles of tunnel, 2 underground powerhouses
• 16.5 MW Green Lake Project -210-foot-high arch dam, 2,000-foot-long 9-foot-diameter
concrete lined tunnel, surface power plant • 22.5 MW Swan Lake Project-174-foot-high arch
dam, 2,300-foot-long 11-foot-diameter concrete lined tunnel, surface power plant • 70 MW
Cowlitz Falls Project-140-foot-high gravity dam, surface power plant • 15 MW South Fork Tolt
River Project - 5 mile pipeline/penstock, 986-foot-head surface power plant • 112 MW Sultan
River Project -262-foot-high earth/rockfill dam • 54 MW Little White Salmon River Project -40-
foot-high gravity dam, 4 mile pipeline/tunnel 1,000-foot-head surface power plant • 500 MW
Mevo Hamma Pumped Storage Project -1900-foot head • 500 MW Parsa Pumped Storage
Project-1,495 foot head and the • 500 MW Arbel Pumped Storage Project-1200 foot head.
Participated in over 60 dam safety adequacy evaluations on all types of concrete and
embankment dams for conformance with the National Dam Safety Act and FERC, Title 18, Part
12.
MRES0196 5
March 1965-March 1971
Senior Engineer; California Department of Wafer Resources
Division of Dam Safety
Performed engineering design analyses of new and existing dam projects, inspected
construction of new dams and rehabilitation of existing dams, performed annual safety
evaluations of existing dams, and performed special investigations of dams under construction
or in response to significant incidents. Dam projects included homogeneous and zoned earthfill,
earth/rockfill, concrete-faced-rockfill, concrete gravity, buttress and arch dams.
Engineering design analyses included hydrology; hydraulics: geological; seismicity; foundation
evaluation; stability and stress analysis of dams; structural analysis of spillways, tunnels, outlet
works; and adequacy of contract documents. Representative new projects included • Pyramid -
386-foot-high earth/rockfill embankment dam and the • Castaic Forebay -179-foot-high
earth/rockfill embankment dam.
Performed field reconnaissance evaluations of proposed sites for dams and reservoirs and
evaluated contract documents for constructability adequacy. Inspected dams under
construction to approve foundations and construction materials and to insure compliance of
construction with contract documents and good construction practices. Performed construction
inspections on new dams and rehabilitation or alterations of existing dams. Representative
projects include: • Jackson Creek -193-foot-high zoned embankment • New Exchequer -480-
foot-high concrete-faced-rockfill embankment • McSwain-97-foot-high zoned embankment • El
Taro-106-foot-high zoned embankment and the • Cedar Springs -236-foot-high earth/rockfill
embankment.
July 1959-March 1965
Civil Engineer; California Department of Water Resources,
Division of Design and Construction.
Performed field investigations and office design analyses including preparation of designs and
contract documents for embankment dams, concrete dams, and hydroelectric facilities
associated with the California Water Project. Field engineering responsibilities included design
related investigations for location of facilities, foundation investigations and construction
materials. Design analyses performed involved hydrology, hydraulics, structural analysis,
concrete and steel design, and embankment dam stability. Primary project involvement was on
the 678 MW, 770-foot-high Oroville Dam and Power Plant Project, with major design
responsibilities on the twin 35 foot diameter concrete lined diversion tunnels, reservoir outlet
works facilities, underground powerhouse draft tube tunnels, and the service and emergency
spillways. Other dams on which design activities were performed included the • Thermalito
Diversion -143-foot-high gravity dam • Fish Barrier -91-foot-high gravity dam • Frenchman -
129-foot-high embankment dam • Antelope-113-foot-high embankment dam and the • Grizzly
Valley-115-foot-high embankment dam.
MRES0196 6
APPENDIX D
REFERENCES
1. Tsunami Hazard to the Facilities of Bradley Lake Hydroelectric Project, Stone & Webster
Engineering Corporation, September 1987
2. Investigation of Landslide-Induced Wave in Bradley Lake, Bradley Lake Hydroelectric Project,
Stone & Webster Engineering Corporation, December 1987
3. Report on the Bradley Lake Hydroelectric Project Design Earthquake Study, Woodward-Clyde
Consultants, 1981
4. Bradley Lake Hydroelectric Project Main Dam and Spillway Grout Curtain Final Construction
Report, Bechtel Corporation, May 1991
5. Bradley Lake Hydroelectric Project Final Construction Geology Report, Bechtel Corporation,
May 1991
6. Geotechnical Interpretive Report, General Civil Construction Contract Volume 6, Stone &
Webster Engineering Corporation, June 1987
7. Final Supporting Design Report, Powerhouse Construction Contract, Middle Fork and Nuka
Diversions and Reservoir Clearing Contract, Bradley Lake Hydroelectric Project, Stone &
Webster Engineering Corporation, July 1988
8. Final Supporting Design Report, General Civil Construction Contract, Bradley Lake
Hydroelectric Project, Stone & Webster Engineering Corporation, March 1988
9. Bradley Lake Hydroelectric Project Plant Operation and Maintenance Manual, Stone &
Webster Engineering Corporation, 1991
10. Bradley Lake Hydroelectric Project, General Design Memorandum No.2, U.S. Army Corps of
Engineers, February 1982
11. 1Oth and Final Reservoir Filling Report, Bradley Lake Hydroelectric Project, Stone & Webster
Engineering Corporation, October 1991
12. Study of Probable Maximum Precipitation for Bradley Lake Basin, Alaska, National Weather
Service, may 1961
13. Bradley Lake Project, Tunnel Inspection Report, Spring 1992, Stone & Webster Engineering
Corporation, September 1992
14. Hydraulic Model Study of Bradley Lake Hydroelectric Project, Colorado State University,
January 1987
PAEABL20
10/12/96 1
APPENDIX D
REFERENCES
15. General Civil Construction Contract, Bradley Lake Hydroelectric Project, Volumes 2, 3, and 6,
Stone & Webster Engineering Corporation, June 8, 1988
16. Middle Fork and Nuka Diversions Construction Contract, Bradley Lake Hydroelectric Project,
Volume 2, Stone & Webster Engineering Corporation, December 14, 1989
17. Bradley Lake Hydroelectric Project, Project Construction Historical Report, Volumes I & II,
Alaska Energy Authority
18. Completion Design Report, Bradley Lake Hydroelectric Project, Stone & Webster Engineering
Corporation, January, 1992
PAEABL20
10/12/96 2
FIGURE NO.
E-1
E-2
E-3
E-4
E-5
E-6
E-7
E-8
E-9
E-10
E-ll
E-12
E-13
E-14
E-15
E-16
E-17
TITLE
PROJECT LOCATION MAP
GENERAL PLAN
APPENDIX E
PROJECT DRAWINGS
GENERAL ARRANGEMENT-PERMANENT CAMP & POWERHOUSE
GENERAL ARRANGEMENT-DAM, SPILLWAY, AND FLOW STRUCTURES
CONCRETE FACED ROCKFILL DAM -SECTIONS AND DETAILS
SPILLWAY -PLAN, ELEVATIONS & SECTIONS
CONSTRUCTION DIVERSION -SECTIONS AND DETAILS
POWER CONDUIT -PROFILE & DETAILS
INTAKE CHANNEL & POWER TUNNEL GATE SHAFT, SECTIONS & DETAILS
90 MW PELTON POWERHOUSE
POWERHOUSE-GENERAL ARRANGEMENT PLAN, El. 15.00
POWERHOUSE-GENERAL ARRANGEMENT PLAN, EI. 21.00
POWERHOUSE -GENERAL ARRANGEMENT PLANS, EI. 42.00 & El. 60'..0"
NUKA DIVERSION, NUKA RIVER OUTLET STRUCTURE, PLAN
NUKA DIVERSION DETAILS
UPPER BRADLEY RIVER OUTLET WEIR, PLAN, SECTIONS & DETAILS
MIDDLE FORK DIVERSION INTAKE BASIN & UPPER CHANNEL -PLAN,
PROFILE & SECTIONS
E-18 MIDDLE FORK DIVERSION INTAKE BASIN & LOWER CHANNEL-PLAN,
PROFILE & SECTIONS
E-19 UPPER BATTLE CREEK DIVERSION-PLAN, PROFILE & SECTION
E-20 REGIONAL GEOLOGY MAP
E-21 SOUTHERN ALASKA REGIONAL FAULTS
E-22 SURFICIAL DEPOSITS MAP
E-23 MAIN DAM AREA GEOLOGY
E-24 MAIN DAM -DRILLING AND GROUTING, PLAN & PROFILE
E-25 MAIN DAM SPILLWAY -DRILLING AND GROUTING PROFILE
E-26 MCE RESPONSE SPECTRA -MEAN AND CHOSEN
E-27 SCHEMATIC OF SSARR MODEL
E.28 RECONSTITUTION OF 1958, 61, & 66 FLOODS FOR BRADLEY
PAEABL2l
10/12/96
RIVER NEAR HOMER
FIGURE NO.
E-29
E-30
E-31
E-32
E-33
E-34
E-35
E-36
E-37
E-38
E-39
E-40
E-41
E-42
E-43
E-44
E-45
E-46
E-47
E-48
E-49
E-50
E-51
E-52
E-53
E-54
PAEABL2l
10/12/96
APPENDIX E
PROJECT DRAWINGS
TITLE
RECONSTITUTION OF 1974 FLOOD FOR WOLVERINE CREEK NEAR LA WING
BASIN CHARACTERISTICS FOR SSARR
PROJECT DESIGN FLOOD
SPILLWAY RATING CURVE
ROCKFILL FRICTION ANGLES
SELECTED SLIDING SURF ACES -MAIN DAM
FLOW THROUGH DAM WITHOUT FACE
STATIC SPILLWAY MODEL
SPILLWAY STABILITY, ANALYSIS SUMMARY
CASE I-NORMAL RESERVOIR, STATIC ANALYSIS
CASE II -PMF, STATIC ANALYSIS
CASE IV -CONSTRUCTION, STATIC ANALYSIS
SPILLWAY STABILITY ANALYSIS SUMMARY, SHEET 2
FINITE ELEMENT MODEL, EL. 1160
FINITE ELEMENT MODEL, EL. 1124
CASE III-MAX VERTICAL TENSILE STRESSES W/0 UPLIFT, EL. 1160
CASE III-MAX VERTICAL COMPRESSIVE STRESSES W/0 UPLIFT, EL. 1160
CASE V-MAX VERTICAL TENSILE STRESSES, EL. 1160
CASE V -MAX VERTICAL COMPRESSIVE STRESSES, EL. 1160
CASE III-MAX VERTICAL TENSILE STRESSES W/0 UPLIFT, EL. 1124
CASE III, MAX VERTICAL COMPRESSIVE STRESSES W/0 UPLIFT, EL. 1124
CASE V, MAX VERTICAL TENSILE STRESSES, EL. 1124
CASE V, MAX VERTICAL COMPRESSIVE STRESSES, EL. 1124
SARMA ANALYSIS MODEL, OGEE SECTIONS, SHEET 1
SARMA ANALYSIS MODEL, OGEE SECTIONS, SHEET 2
SARMA ANALYSIS MODEL, NON-OVERFLOW SECTIONS
2
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~UILTEXHIBIT I PEND~G FERC APPROVAL
' FEBRUARY 1992
BRADLEY LAKE HYDROELECTRIC PROJECT
ALASKA POWER AUTHORITY
PROJECT LOCATION MAP
PLATE 1
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ALASKA POWER AUTHORITY
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PROJECT DATUM.
MEAN SEA LEVEL DATUM= PROJECT
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.& STONE & WEBSTER
ENGINEERING CORPORATION
FIGURE E-2
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FEBRUARY 1992
BRADLEY LAKE HYDROELECTRIC PROJECT
ALASKA POWER AUTHORITY
GENERAL ARRANGEMENT
PERMANENT CAMP
& POWERHOUSE
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PENDING FERC APPROVAL
FEBRUARY 1992
BRADLEY LAKE HYDROELECTRIC PROJECT
ALASKA POWER AUTHORITY
A
CONCRETE FACED ROCK FILL DAM
SECTIONS AND DETAILS
PLATE 3
FIGURE E-5
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// / ----11,0-------
;-/ PLAN-SPILLWAY -------
/
EL 1195.00'
!CONTRACTION
:-::~':'::::":;==:;::~_j JOINT
;RAINING WA:...L
[A$; TRAINING WALL E ~f.i':O~N'~3 WALL
ELEVATION LOOKING UPSTREAM
=-~;~:;g:=~
•·'1 : ~-6F1'
R;·
!
(
-r.£AI.',
y
lSPILL-Y
;BASEL H~E
'~" L '·"-
\I :,, ;,
t
F-~~ \i
t
l
PC~
::·j 1
PT 1
r'c 2
pI ;;.'
P1 2
GAL:...::PY
~C/.:.::?5",:.:_,
CJRVE EOUAT iON
Y• 0.0678X '-848
OVERFLOW SECTION GEOMETRY
.-SPILLWA'I Bt..S£:...1~~
2'-
ScOPe. ~•Gi-l ~""
E-'1 ~5.08
~~
:..-L
G:...~U:::h~
NON-OVERFLOW SECTION GEOME
~s
NTS
F!LL C:::'~·:RETE
TRY
40~:-r: .....
:,:A:...E A: 1~~ :co•
;:ll AS.BUIL T EXHI
PENDING FERC APP I
FEBRUARY 1992 1
reRADLEY LAKE HYDROELECTRIC PROJECT
__j
ALASKA POWER AUTHORITY
SPILLWAY
PLAN, ELEVATIONS & SECTIONS
,4;, STONE • WEBSTER I I
ENGINEERING CORPORATION EXHIBIT F PLATE 4
FIGURE E-6
r
PROB_~~~~-FLOOO ~~.~
NORMAL MAXIMUM QPERATH~G Ff(S(RVO!R LEVEL EL 1180 o·
/
/
/
ROCKFALL
EL tl20.0'
/'~
,~
"' /
~// EL\0965'
'*-~=-'-"-'-"-" -----iH+H+-+-
EL 1076 a·
'o >s
'i, TUNNEL
1 -1
SCAlE A
"' "' ;!?~'!"
1/'1~11\f")
N
~":"
"'""
GRO
liNt: (APPROX}
2-2
SCALE A
RINGS
r2
l.2
I
I
I
I
I r,
GATf SHAFT----
EXCAVATION
SPR!NGL lNf FLOW
DIVERSION TUNNEL SECTION
SCALE 6
FLOw. __
· i:-TVN'Nt:L
PLAN OF TUNNEL
SCALE B
1i SHAFT
l
()
3-3
SCAlE A
AIR
4-4
5 CALE A
--
(t_ ~ ~=i A-r"1---·--~
I
I
\
~-\HYDRAULIC GATES
-PENSTOCK VENT
I
DRESSER C 0 UP L..lNG
F '1 XE 0 RING SUPPORT
s Ll DING RING SUPPORT--
{TYP)
r4
l.4
"' ' i
1 40 ·o··
BENCH
\
'
"' ::c:
V10
' ' '\
51
' ' EL 1062.5'
IEL 1060.0'
(};)
!IV
·~:::~]
101: o·
AS·BUIL T EXHIBIT
PENDING FERC APPROVAL
FEBRUARY 1992
BRADLEY LAKE HYDROELECTRIC PROJECT
ALASKA POWER AUTHORITY
CONSTRUCTION DIVERSION
SECTIONS AND DETAILS
'<!+-++ -_fl--'..Q~
0 ~0 40 FtET
SCALE B: 1": 20'
5 5 0 8 =it Ft.El
SCAlE A I
SCALE A' )",8'-0"
A STONE & WEBSTER
ENGt"''EER1N:G CORPOR~TtON
FIGURE E-7
PLATE 10
w
~
_J ~~ ~ -' ""o !li <to:O lr LW~
o: ... -i ~~~;;j
LLQ=¥-
Q I -~ "Vl
. , . .,
... "'
9
_t
-SEE LOWER BEND
DETAIL BELOW
0
9 g
8
6
!!I
8
0
~
BRADLEY RI·JER
FAULT ZONE
I
0
0
6 :::
1dLG,1"i!> ROCKBOlJS
I
0
0
0
~
. ~·.-;=-:.!,_~;-.;.~~:~o.;--·~~
·a
-' !!!
"o
-~
1...3
INTAKE DETAIL ...
2-2 ...
~ -;=::::--::~
SCAl.-f•nn
SEE EXHIBIT F-PLATE 6
FOR INTAKE &GATE SHAFT
L
UPPER SEND DETAIL
... 10'
,..,._. •• ------:=:s
ICALI.fiiT
3-3
... JO .
Mf" I
~e-.a.t•un
<0 ,.._ .,
\!2
<(
I-
V)
---------------...... ,
""17 SLOPE;--I 0 8 0
0 0
~ ;:
1ci'IJ SCHEDULE 40 PiPE IN
14"(1) PILOT BOREHOLE-
FOR SHAFT ACCESS
71
8 0 0
7j 6 0
;:;.> Ol
,--------!----BULL MOOSE
FAULT ZONE
0 I 0 . 0 0 0 I 0 0 R 0 <0 <D
TUNNEL
CONTACT ..,__-+ _ __.~GROUT
HOLES
CONCRETE
LINING
0
0
0 .n
--2500'
--20001
NORMAL TRANSIENT PRESSURE GRADIEN--T-]L------
--15001
ffi z ::;
w w
<n g C STATIC PRESSURE GRADIENT
ts..
~r ., ......... _____
·-"'
? 1.-:;0
0 J 0
<I' 8 0
CUTOFF l'l
GROUT
RINGS
--10001 ~ ~ ~ 2 CONC
--500' r
8
0
N
TRANSITION FROM
13'0 CONC. LINER TO
1111> STEEL LINER
STEEL
PE~
&MANIFOLD
TUNNEL & STEEL LINER
e•.o• e'-o"
l---t-----,'---t-~
STEEL
SET
STEEL
LINER
!\~ . ~ ---.,--, -+J-idl---
c;o
r>-
¢
STA184•141
t TUNNEL
m··
4-4 ..-
~C.Au••ul'
-MANIFOLD
.. (HORSESHOE
i:.~~~ce~~~~ON I
POWER TUNNEL ---J
I
L----
-++-----+ \'' STA 177.67! ·~ \/*
•.
g
;
~
<[ ....
"'
REINFORCED
LINER
TRANSITION FROM
11'ill SHAFT TO 13' 1/! TUNNEL
LOWER BEND DETAIL .
~ s
DRAINS
(TYP)
6-6
II 4 I'
~-
9-9
~----...:::::::::s
StA;.f N F'([T
1' THICK
CONCRETE
LINER
5-5
4' I'
~--i KAU•fln
r ;. r ~~
HOOP &
LONGITUDINAL
STEEL
REINFORCING
TRANSITION TO STEEL LINER&
AREAS OF LOW MODULUS ROCK
8-8 -..
AS.BUIL T EXHIBIT
PENDING FERC APPROVAL
FEBRUARY 1992
e-•
ICALI •flU
A
BRADLEY LAKE HYDROELECTRIC PROJECT
ALASKA POWER AUTHORITY
POWER CONDUIT
PROFILE & DETAILS
FIGURE E-8
PLATE 5
HOUSE
y
EL 1194.0'
EL 1185.5'
I I 22' <!I ·If':. 1'-0.NOMINAL l ' CONCRETE
LINING
l
1 ~ J Jr SPIRAl STAIR
AIR VE'Nl
~1067.5Q;__~-" HA'l tP:I
HYDRAUliC
GATES ,
LADDER ' •n
BY-PASS
EL 1055.0'
2 ,,
--:3>1'---·--t------~ TUNNEL
GATE SHAFT CROSS SECTION .,. w--1
·~·lt .. .-~ fT
'/iTsiil•f
TRASH ROCK-
..
~
INTAKE CHANNEL
LONGITUDINAL PROFILE
EL 101B 0'
0 15 32FEE1
",....-----"'";,..,NNEL 8Y ·PASS
-ACCESS MANHOLl
PLAN
GATE CHAMBER
10' tO'
st•Lllk 'f.f"
ACCESS HATC.-;~
,.
SCA:..E .;6"
~Gt.T" S..;AF' CAP S_AB
I
,_TU~NEL AiR VENT
TUNNEL R£j:"JLL YE~T~-.
,.,--GATE POSITIOI\: !ND!CATOR
CAY7ANK~'
0 ~
GATE HOUSE FLOOR PLAN
o 10' 'tO'
y.-~
1
r-TUNr-.JE._ EW-PA:,S
MANHO~E
:u:jNE~ REF1:._;_
"~"UN~J£i.. REFILL PiPE...,_~ ~ GATE SHAF'T
PLAN
EL 1053.50' w--r N'
S!:lh.E 110 ft:lT
PLATE 2
PLAN)
A
PLOT PLAN-GATE SHAFT
c.:::a:: 1
~•u ••ufT
AS·BUIL T EXHIBIT
PENDING FERC APPROVAL
FEBRUARY 1992
BRADLEY LAKE HYDROELECTRIC PROJECT
ALASKA POWER AUTHORITY
INTAKE CHANNEL &
POWER TUNNEL GATE SHAFT
SECTIONS & DETAILS
STONE I. WEBSTER
ENGINEERING CORI'ORATION
FIGURE E-9
PLATE 6
------
-,
~~
rOAD
~· .TROLLEY,
eo:., a"
12
-1
E
24'·0"
c: "·r 1
T -----{ = _j_ <B?l~/ J:
; . 25 't HOOK T
1-GRAVEL SURF ACE
E.L .!i '±
~11'.fERSTL 9'0 STL MANIFOLD
1 i INTERSECTION L ~ INTERSEOION 1: INTERSECTION \9' ~ STL MANIFOLD -·,.~l /POST-'ENSIONED
i I r TUNNEL ANCHORS
-l ~fif MANIF'OLDENCASED ;--6'-6't> STL
---------------------;----.... INCONCRETE ' PEN;TOCK -------1 -,....~ -r----r J-", ;--.. -.. EL 2505' 1 '
--·----~)· ""'I ----~------------------=;,~'2~:c-~--;'~d-_" --~:·rtt:~r~~ ·~ I /...._ l I J.;.._ "'-1-. • ,
' ~=----=-' -·-' --------~~~~---~1:~---'-"'~'-
LINER DRAI~sf If •k' REDUCER---'~
THRUSTBLOCK--' SPHERICAL VALVE -L,_, I 1 I I . 1
PENSTOCK THRUST RINGS
PENSTOCK, MANIFOLD & POWERHOUSE ) lll
0 10 20 F'EET
30' LG POST TENSIONED
6'·6•jiSTL PENSTOCK ROCK ANCHORS
11' f SlL
LINER--
6'-6"DIA PENSTOCK
IN TRENCH
NTS
I
~ STL LINER
LINER
eNCASED IN
CONCRETE
11' DIA STEEL LINER
0 !0 20FEET
DRAINS
PENSTOCK CONC ENCASED
7(F'UTURE)
t~
I
I r HIC>H PRESS\jRE
ELLIPSOIDAL HEAD
r:·;·~l I I I 7 EL 1!\.0'
FUTURE UNIT EXCAVATION
0 10 20 FEET
£L41 1
~16'
TIDAL FLATS
EL VARIES
IEL 6•!)
r---160 rN HOOK
A
,• ~-: . ~ .
s;:~oo.7
~·
GATE
EL 21'
RUNNER .j.-~~S~HIGHEST TIDE "il/. EL 11.4'
~
A5-BUIL T EXHIBIT
PENDING FERC APPROVAL
FEBRUARY 1992
BRADLEY LAKE HYDROELECTRIC PROJECT
ALASKA POWER AUTHORITY
90 MW PELTON POWERHOUSE
STONE & WEBSTER
ENGJ>fEEAING CORPORATION
FIGURE E-10
PLATE 9
g
FILL C(:,N('"(TYP)
1/ g6
"• ~~/ PENSTOCK(TYPJ
1 1 ° I
I I
.J
~~
...-8----·£.._id_N_ITS ~I .,,
:~~ I
Y t J .. • . ! , ... 1'':' l .-----,L.---+:H \ ---+W ... l . -' L: .,\ ---+ 4
RUNNER REMOVAL I
SUPPORT PL.ATFORtvl I
EL 5.00' ! ~ I
I ~
1:1 ~~~\-; ,IJ•I .. .1 , ! .)j . .. . ,:;~~1
i ., • ~j;'~ : . ; .. :~~~ ·--+-· _L______l__-1 E
TAILRACE
TAILRACE
SPIRAL CASING PLAN EL 15.00'
0 8 16 FEET
SCALf A: {•,-·0'
A
A5-BUIL T EXHIBIT
PENDING FERC APPROVAL
FEBRUARY 1992
BRADLEY LAKE HYDROELECTRIC PROJECT
ALASKA POWER AUTHORITY
POWERHOUSE
GENERAL ARRANGEMENT
PLAN EL 15.00'
PLATE 24
FIGURE E-ll
3 MTX-XMl
\SPARE)
.,.......-TRANSFORMER PIT
EL 18.00'
T RANSFORM"R YARD
TRUCK SlAB---I~"'l.
FU!OL OIL
DAY TANK
GUARD
SPH VALVE a, i
PENSTOCK I
~SPHlRICAL
TURBINE FLOOR PLAN EL 21.00'
TOC EL 21.lX"i 1 IUNLCSS ,:-~ ... ~\·:S£ '\:.'7~0!
LEGEND:
MCC MOT C'fil CO!\. T ROL C£1\o 1 E'i
!=HC :=-:fiE HOSE .:ABIN[~
ON DOWN
!'-'H ""1.ANHOLE
SPH SPHERICAL VALVE
0 B 16 r'€ET
I iiil
scALE A• f·r-o·
A
A5-BUIL T EXHIBIT
PENDING FERC APPROVAL
FEBRUARY 1992
BRADLEY LAKE HYDROELECTRIC PROJECT
ALASKA POWER AUTHORITY
POWERHOUSE
GENERAL ARRANGEMENT
PLAN EL 21.00'
ITON!i I ""£liSTER
ENGINEEA ... G CORPORATION
FIGURE E-12
PLATE 25
51'6 SUBSTATION
ROOM
l~c;;· ....
CRANE STOP
FAf'.: RM NO , STORAGE RM
NO.1
2Q'·_o·-····
···~-+·-~--··--'"':(.
GENERATOR FLOOR PLAN EL 42.00'
HANDRAIL
FHC
RM
I~
--+-
B7
' MACH' NE SHOP
I . ' ~--~s;-:.. __
. 1 ! t l
!
_j1
(P._ATE 27)
AS-BUll T EXHIBIT
PENDING FERC APPROVAL
FEBRUARY 1992
:%I BRADLEY LAKE HYDROELECTRIC PROJECT "i ALASKA POWER AUTHORITY
I POWERHOUSE
. . PLANS EL 42.00' &. EL 60~0'
0
AIR INTAKE
CANOPY___..,.."'
·-• ---r" GENERAL ARRANGEMENT
~ n~E~ ~=~~=~===-~~~~~~~~=~~~~~~----
PLAN EL FIGURE E-13
0 E\ 1€ '"EET
,~ . . SCALE A; 1!•1-0
,,"'"
~~~
,"'' ., .... --
' I 1 I I I I / ,/
\ I~ I~~ ~ ~ \ \ ,' /
I 1 1 \ 1 \ I 1 I I I {
\ ~ I I I \ I I I I I I
\ I ', \ \ \ \ \ \ \ : :
\ \ \ I \ \ I t \ \ \ \
\ I 1 I I \ I I \ 1 \ ,
/',,""""
I --\ \ \ \ \ \ \ ; \ \ ',, \,,
\ \ \ \ \ \ \ \ \ \. ', ... _ .. __ _
\ \ \ \ \ \ \ \ \ ', ....
\ \ \ I \ \ I \ '-,
\ \ \ \ \\ \ \ \ \, -....... ______ ......... \ ,, ',,, \ \ ............
\ \ \ ' \ \ ' \ ' ,\ \ 1 , , 1 ' ' ' , NUKA POOL
\ \ \ \ \ \ ',, ',, ',, ', ...... ', \ \ \ \ \ \ ', ---------
\ ', \ \ \ ', ', ', ' \ ' \ \ ' ', ............. ',, \ '-, ',, \\. ',, ' .... , ..... ___ _
', ', \., ', \'1. ' ... , ' ...... ...
I \ \\ \ ', ', \ '...._ .. \ \ \ ' \ ' . \ ' \ \ \ ', ', \ \\ ', \ .... ,
\ \ \ \ \
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\ \ '
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---...........
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////'
/
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+
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/ / II I I
I
/
I 'I I ,' /j 1/ I I
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I I 1
I I 1
1 I I
I I :
I
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1 ttlo
I ~I ,..,
' I
I
I
I
I
'
/r-l ........
// ~LIMIT /:.. L~x~
22)
SLOPE 4H.1V
a,•
.0.
EXISTING NUKA
RIVER SHORELINE
))
"'~ """" DO NOT EXCAVATE)'
(
PILOT
CHANNEL
ltli.~7"'
~
---r-~~-~ ___ L_
PLAN-OUlLET STRUCTURE
SCALE A
FLOW REGULATOR PIPES
2 EA 12'~
SCHE.DULE 40 STEEL PIPE
\"'""
~l
o I o I t'"'~
<1 I ::y
J
0 ~! 40 FEET SCAL[A:~
6] '--·--y ·~,~·:('"UPPER E<"A[JLE• ,.\[<'
-~\. ~O~~~ET WE1h _/' \ ·.. / 1 \~~~(· ()
.e . ~ .. NUKA '"'1 .
GLACIER \ \ s·
' l C.J) ' .
) ) \ / t! NUKA POOL --~
/ .. ..../) (
I I 1:. . I (.., ·. :
I ·.
/ \ _jr_r~~J0NuRE
DIK~j. K
NUKA RIVER ;~·.
AREA PLAN
N.T.S.
A5-BUIL T EXHIBIT
PENDING FERC APPROVAL
FEBRUARY 1992
BRADLEY LAKE HYDROELECTRIC PROJECT
ALASKA POWER AUTHORITY
NUKA DIVERSION
NUKA RIVER OUTLET STRUCTURE
PLAN
~ STOM: & •n.asTit:" I ~ ENOINEER .. G CORPORATION EXHIBIT F I PLATE 21
FIGURE E-14
L
lxsT
GRD:z
1L
EL 1282.0'
EL 129.::! Q'
li_ DIKE
I
LinER
SLOPE
...--APPROX T.W. LEVEL I EL 1290'
41-1 1V SLOPf / /·EXST GRD
~........ . •. ·.·I I -j:!: • =:.......c... . -. I ~ I I '""
I
CH.L.t.J'.JEL ~ __...-GABION LAYOUT r SYMMETRICAL ABOUT CENTERLINE
35,,.0_' -----------~-1
E L 12 97.0'
---------------------~
•L ·<~"V lfl ~ <'"r J 0 11 I I · · · · .1 LIMITS OF----I
MEMBRANE LINER :
" ,: : 'T F -l-=c :.: 1r-
jvn!~;:83tJ L.' 1~J":±.;l~w 1 \~> ! ''~xvL ~J~ I ~"1
, .,
EXCAVATE TO
STAB-E SLOPE
EL 1277.0'
FAR SIDE &
NEAR SIDE
1-1
SCALE A
c_ DIKE
4L1296.7
I
100'
>jW I -o.. IO .-,-' "'.
\_GABJ•)NS CUT
Bi X:CTION
[.....----MEMBRANE LINER
I
I
I
\
12"x12" PRESSURE
TREATED POSTS
2-2
SCALE A
DIKE GABION LAYOUT DIKE
40'it1-, SYMMETRICAL A~OUT . li_ 1 CENTERLINES
I
llllllllo· D
1.5' ~ I 1-zQ._
II ! I~-~-~-( :g-·-li_ CHANNE1
CD EL 1282.0' @) EL 1291.0'
40'~
]1
E~ ~29E:
,-EXS" GRADE
!c:'/G I
1 =:,_cc=1~~--~--lf=4 '"7'
1 -t: I --1 I ·----__ _~. ___ ::.-.:::
=====--.:z:-:::7
I fJ
"'0 I )1 l II I I I I "0"' '" II
\ I ~-~ I J ~ l I~~ I I l I I I I I ) I
EL 1290:! 0
'"
FLOW SLOPE 5H 1V 0 ---ail-I I f_ CHANNEL
i2~ SHEAR
GATE
z-PILOT
CHANNEL7
-(
'i_Qi__
@ EL 1285.0'
i
I
401
-----. n
r~
I ----r
D
@ EL 1294.0'
3H:1V SLOPE
ITYP)
/
.!..._TRANSITION FROM
3H:1V TO .::IH:1V SLOPE
.::!H:1V SLOPE
ITYPJ
Ci!~
"''::;:
I
I
-··1 ~
r
I ,
LEL 1296.7
~ ~ I+,......._._..--------
ENLARGED PLAN-OUTLET STRUCTURE
SCt..LE A
EXIS.,-ING GROUNC>
EL VARIES
It_
3-3
SCALE A
li_ CHANt<-~E~L ___ _
G) EL 1288.0'
I
I
I
GABION CONSTRUCTION SEQUENCE
SCALE B
0 10 20 FEET
SC.A-E 8: 1·-·~'
----5'--1C' FEE:
,._:-
A
AS-BUll T EXHIBIT
PENDING FERC APPROVAL
FEBRUARY 1992
BRADLEY LAKE HYDROELECTRIC PROJECT
ALASKA POWER AUTHORITY
NUKA DIVERSION
DETAILS
FIGURE E-15
PLATE 22
0
0
~
$~~::::;;~
g
N
$
M ~2078400
--.....
PLAN
SCALE A
/
I
I
I
' I I I I ' I I I
/
/
I
/
/
I
I
I I I /
/ I / /
/
/
I
I
!,('::7V
1280
4-4
SCALE A
5-5
SCALE B
A5-BUIL T EXHIBIT
PENDING FERC APPROVAL
FEBRUARY 1992
BRADLEY LAKE HYDROELECTRIC PROJECT I ALASKA POWER AUTHORrTY
UPPER BRADLEY Rr ·--
OUTLET WEIR
PLAN, SECTIONS & DETAILS
PLATE 23
FIGURE E-16
I
~\ -. ;----~.::_
"" ·~ 0 \ !...MF 1 , N2108180.0
"E356663.3
\ STA 9~00 \ . \ ~~~ ~ .. ) \·~ .
s
iNTAKE BASIN
2220
MIDDLE FORK
BRADLEY RIVER
CHANNEL 2200
2180
2170
2160
I 2140
2120
croo 1•00
-
0 :;:
< ....
"'
2•00 JoQO
2
-2 'I• SLOPE
4•00 5•00
STATION
<i PROFILE
I ---,o:---r' . 2'
MIN
TYPICAL
CHANNEL EXCAVATION
IN ROCK & OVERBURDEN
(NTS)
LOOKiNG UPSTREAM
6•00
~p
7•00 8•00
"' ~
;!
"' -> Q_
~
1
sLOPE VARIE:O
"""'··~/[.>----2--r----:2.__-1 r;;;u--
-' :-11 1 ,-:;
2"LJ~
~ MIN
TYPICAL
CHANNEL EXCAVATION
IN OVERBURDEN
(NTS)
LOOKING UPSTREAM
9-00
3:
)> .... n
J:
r
z
"' ~
~ rn
;;0
~
)>
'f
0
~
WASTE FILL
AREA 2 -------'
2-2
WASTE FILL
AREA 1
(NTS)
t WASTE ~ILL
AREA i:
CHANNEL
~
WIDTH
0 40 80FE:ET
'--~-j
SCALEA1"o40'-0"
AREA PLAN
INTS)
SLOPE OF EXCAVATION
STA 0•00 TO STA 1•70
AS PER· TYPICAL SECTION
cOR EXCAVATION IN
ROCK & OVERBUROEN
Jl BASIN
I 1 ~7r~"
,_,
A5-BUIL T EXHIBIT
PENDING FERC APPROVAL
FEBRUARY 1992
BRADLEY LAKE HYDROELECTRIC PROJECT
ALASKA POWER AUTHORITY
MIDDLE FORK DIVERSION
INTAKE BASIN & UPPER CHANNEL
PLAN, PROFILE & SECTIONS
PLATE 11
FIGURE E-17
21BOL-~ 0> 2160 .. z ....
0 V>
;:: 2140 -.. -> w ~ 2120 ';;:
w --' 10 2100 a_
w z
--'
I
~ ..
~
11•00 12·00 13•00 14•00
STATION
Cl PROFILE
15<+00
U'
0>
CHANNEL
CUT
CHANNEL
EXC
I· 'ILL 1\ :-~ v,,,I~SI
fi!~2 FOO'MAX
40'MIN -~SoO'MIN
-----...:::-....... 2 .. ::;--,'7, ................ ......
D!FFEREt,JTI:,TED, '::_'' '' ~ ~~STE FILL~ ',, -
EXST
GRD
3-3
WASTE FILL
AREA 2
I 500'MAX bO'MI~ I
li!J I ~ MIN 6' SHOT ROCK
4-4
WASTE FILL
AREA 3
40 BOF"EE T ----,
A5-BUIL T EXHIBIT
PENDING FERC APPROVAL
FEBRUARY 1992
BRADLEY LAKE HYDRO ELECTRIC PROJECT
ALASKA POWER AUTHORITY
MIDDLE FORK D I VERSION
STILLING BASIN & LOIVER CHANNEL
PLAN, PROFILE & SECTIONS
BTONE & =~;TION I EXHIBIT F AE .. _ PLATE 12
FIGURE E-18
r·· , 50.0' EXISTJN
WORKING LIMITS CHANNE~ ... JI.
I -------. ··r ------------,, : I"'"'~ \ :
0
,/-______________ )_ GRADE
!N 2.099,50~
• 0
! ~
~ ~
I "'
I 1 I -
I I I I / CHANN •
11'1!.1'' "~ '-r--+--;/ '" ,'\.\'i'"
BOTTOM~ : I
kJ
E 3<4H5.55
N 20qqq37,43
t
w u.J
t~ ;:,1:),,5:)0
--·-.. ~-~·-.. --·-· ·-· ·-... -... -... -.. -··-··-.. -··-·· -.. ·----·. -~--~-----· ·--·-··--· -· ·--~----. ·----··-· --· ·-··-··-.. -· ·-· ·-··-·--· ·-·.-··-·
',,:I:ERSION DIKE
',, EL 1342.00'
2
i
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GRADE~~-3
i
TRAINING DIKE ~-~-
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21E8>
DIKE PROFILE
NTS
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EL 13<2.00'
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I
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DIVERSION DIKE
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PLAN
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ARMOR U/S & DIS FACE
OF DIKE 1/ITH BOULDERS
12.0'1 1 0 EL 1342.00'
u.J
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v
~
----·--··-··-··-·--··-"·-··-··-··-··--·-··-··-··-··
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BRADLEY
LAKE
DIKE
I ~t m5
·
0
' ~XCAVATE ADJACENT : TALLUS FOR TRAINING
---~----~£ CGNSTRUCTION
nrsTIN~-r 1 • 0· 1 GRAOE~ ~
3 -3
TRAINING DIKE
IC7l
NTS
II
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~ ...
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AS-BUlL T EXHIBIT
PENDING FERC APPROVAL
FEBRUARY 1992
BRADLEY LAKE HYDROELECTRIC PROJECT
I ALASKA POWER AUTHORITY
UPPER BATTLE CREEK DIVERSION
PLAN, PROFILE & SECTION
~~ STCIJ: • Wllt$Ttlt
£HGtNEERlNG C.CJfP(IRATION
FIGURE E-19
6]
II A C If
Tri~
Jtk
AfD -\...as ~-... : . ~ ·.. .....~~
:' KJnn ~ ••• ~.~~··••
: ~: . .
Kjv
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............ · ...
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... :~ ...... ; .. :-:-... ,
....................
. : •
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) --II
SCALE A• i • • 10 MILES ;c.
-t-
-t-
---
u
i5 QUATERNARY
N
~ TERTIARY
u
CRETACEOl.5
.AJRASSIC
AND
CRETAC£ClJS
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---
ANTICLINE ·GENERALIZED ON SURFICIAL DEPOSITS
AND IN THE OFFSHORE
SYNCLtiE • GENERALIZED ON SURFICIAL DEPOSITS
AND IN THE OFFSHORE
NORMAL FIUU' ·DOTTED WHERE CONCE.lLED U,
UPTHROWN SIDE D, DOWNTHROWN SIDE
THRUST OR REVERSE FAULT· DOTTED WHERE
~AUD, SAWTEETH ON UPTHROWN IL.OCX
CONTACT
QUATERNARY DEPOSITS
KENAI GROUP: SANDSTONE, SILTSTONE AND SOME
COAL
GRANITE, QUARTZ MONZONITE AND SYENITE
~frDfliL~~~NEMEI:r:~=h:
MCHUGH COIIIPL£Xa WEAICI.l' ME'lliMORPHOSED
SILTSTONEMGRAYWACX~ ARKOSE AND
~'i'fH~~ Tl<;.DSA::GI~f t CORE ENSTONE,
LAVA FLOWS
LIMESTONE AND
CONTORTED AND
FINE GRAINED TUFF
SOME GR£ENSTONE
MAFIC ROCKS • PIU.OW BASALT AND SOME
GABBRO AND ULTRAMAFIC ROCKS
~ IT~a--~ IJ ---~1'10111
CHERT
6
GEOTECHNICAL INTERPRETIVE
REPORT
FIGURE E-20
62°~ 0 -7-..... . 152° (~, .. ---····· ··\.. ' 144' 142° ' , ·' ,, r----I --' __,.---, \_ .i .. -_,e• " I i • I ' >o •
• ' ------' > ' . ' ', f, •• c~---~~~~ro o<• --~.,. ~'-; .te;, '>~'~' "'<,. ' ·~-____ ,. ...-~ • ~.... . . .. • ...... ... :::._ "+. ' ', ..... ,,
' ··-·· -/ y . ,--' • " ' ' "· ' ' , D -~ . ' ' ' .• -• ~~ , ' ' '·' ,• .... r -. ' • ' . • •> • '
"'
,,
; , , ,
1,'
I ' 'I I
I
).,
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................
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... ··
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'\
_., , --i; I ~· ~ {"'-'·• ~ -····'-I.)> Nooood '-
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c. ,"/' . . . .. f~.J"'"'~\\ i· ' 't "o/k J /jj ""' . ..... •, ~ '-----
--·' ·• .n . -~· ,-. -~ ~
~
-N-
~
('"~,"' . .. r· . / ... ~: '"" ~· y 6 -.. ~--•. _ . .,.. ·-..
.s -;.?r ~<"" _ ({> Kenat ..., ./ #. ·,., ~nao ~~ ~ 1 ~~ ~ /--::.{," '··-..-:::--.... ' , . . ' ' "'' •.-" -> "'" • -"'~' C>!< f -:···· •? ~ " d' , ~. ·N' 0 •o ,o • ·o~;_/ ·--••' "· , ,, , r~-...-· , • • ,· o:a;, ·" ~ ,, ' '""'" " _, ~--• /' • '.::':. i~1 ·., / 'jp,::.,~')' .l ~1 ' 1 ~ ~ ·-c;j!ff--., -~.r~'~'~,-...~.::.:~---->·····----..
/ 'i .. ' / ., .>--. '-'' •' •·-~·' ill / ~ PI "' '1_, ~ rl ,_~ (: ·" ...--...--...._ -~ ~ , jz'--j ,• ·.f ,/ :t #"!I '-! . \ It I J:"'l!l'::" .-~ ,-:;; •· . ...._ .-· .::-.:;;.,....-,' -~.;-:::.....=--:!. "--..
(
,~.;'"14 ~ !'lf~:i --;: (;·:/ A~ ... ~;" ~~ .... "Bractley rv\\ .~t...i:QlJ a:rrJ7 il ,~~~~--__ ,._ '~ .N --;~ -~-~ '~\. ....\ 600
• .:~<> .. '"A.'P.'f...t.../ H ( '~ .... /-"' Lalit~ '' , ... ~" -"F ~ ... ~ --~---' . " -~ -~· ..... ~-,-.-~ ,U • omM . ..>< ' ~.. / ! ' ,• '"~ I __.,---· "'' ' ~ ,-J' -'
...... ......_,_ ..... ~ .... "" ~~chemak s~.Y. I 11 ~\ / / • /'/I ,' -... ---/ >-~!7.tf... .,•_./.---1-' ' ~---~ ' . ·rv .. -. • " . ) 11 .. . ·-~~-' • r. ' ' ' . ' '-:..~ : " .... ,. -,' . . ·;'""" ,, '" .: i ; ~----~-'" ' :.,,/ ·. . . f ,' ....... . ' .,~ r Seldovta~~ ]\"' :', : J I ,c.::?" 1 I' ' , . ., .. ,,I • ,---·--flAY '•
·· ~ ,• : "n -' / • 1 -.. --, -// , • "' "" •• tr
'"' " ,_ ... +~ ' • ' " •-< "' ... ' --· ' ~ .... ,. • ... ·, , ..... ·"' .. . ' . .... ' .J:; -~. •/ ' i c..:o· ~ .. i / / --.::: ' '/ . . .. _.,.. ' ,: .. --' ""'~--. ' .... ;,.. . ." ' ·' ' ' --··-'· -~--~ ' <f,\ '--,• :---,\' i.. '/ ,_.•'/ / ___ ., __ .... ~ ~~••' ' * . ;,i / V_... } I //"""-···' T ~ f• • .. ~--.•:< ....... ,,.•;·. ' .. --------v C'l. / / / -.:. • .... ' ,..... -----... ,. : .. . ,, " ~:jr ~ / .. / , ' I ./ / ·-":y' /. 7 ........ " * , "~> ty-" '• / / -.u· I,, ' >,,.;--. .. -/ .. * < • ,, .-· ' • •V ·. ~ """ ..... (. ~,.. •.o-• s < '"' ...-./ .• ·.f.x / 7----. ~"/ """" "··-.
... -..... ,...,. * I, ~~w ·lim''\.' ..--• .. ~ -!!"il, ' '/ ~· :e-' ,.., • ···. 4"' '" . ' (' <' '·" / •'' ,; (' 1 .·~ ~~ True ~~ • . ·. . ' . " ' ' ' , .. . . "'" ·-. r'r' ...._,--f :--~·-··;, : · ,.-,.-:f::SJJ 0 -' 0 _... . ..-/}"~~-~-' ~ ;~_.: , , • ..,:-...:;_-..._
rl, y~~'-...5~ .. -,f-e?I··~Ma /"1_ •• "'"' /. I', J \ / -197s')•. ., . ' . ·.. .' . . ~"" ~ / ' ' '. . •. ' . . " ~ .->' -·> •;?-'l" • ~~ ~ /,.·· -~ '::~' ,/_ ;/::l./ •, G U L F,~+, oF A L A S K A '
'}. · . /'~')"' f'lf 1;. ~-~0v {,. __ .. ...-,,;.... ~ ~.~' ·~._J \. v'/ ' ( / / .'
1
V ,. '}{-..,-~~ / •"" '-. v"/
., ,.-/..~c.\. -/· //,._; , ~ .& : ' .. " ---=-' ,• • '' v-,_-..,.:.r;.7 ' 0'" •' " / ' ' ' . ;_..,.,. , ' ' ' . . ' '~ ,. •'
" j' r--. /)· " .. .,.,. / ,/ ...r __.zcfl /'<-"' Yf, "' " ~II';-/ . 'Vfll I .• .,. _./ .f/' LA (FIG 8)
""
1460 144°
142°
150° ...
1520 150° 148°
E XP'l..AHA TIOH
Ac1 .... ,...., ...
--.-....,... ~ ...... ,...,.,, ~,.,.,.,.,... M!Ofo••,..,_,.,.., lWiit'N
QIICM....,~ftWICI'~QII~l·~
....,..,..., ·~· ..... , ..... ,. 00."
~.._otlwt.
-......, ....... ...._,._ TPII'\Itf J. .... t. ~......,.. .JIPQI'Oalm..-.v
l~. OOrtlfd ...,...,. ¢01'1c.•fl! 0t
Qtlff'lfi(W>.O. BM!'A of'IQic.at• !'1'1,h_.V
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.......__ ---::::;,..-Stf'•ll•$110 FM~Jt. ~ .,...,. IOO"O••""'tfly
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dawfttt~tQWft IHII of ta.1'
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.......... .... OdUCtl'9 IIIII,IICt\jl,.-,
1........,. , .....
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~ ..... ~..,01~1~
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-.....:~. OOil1I'O ...,..,. c:GNII't*H or ...,.,101"1... .... llldte.ll ....... """. .......... _ .. , ..... _
-~-···-Stm,.Sho '..,,. _...., .,.,.... ~,,.,..,...,..
~.CIQlll"'ttiG~~Of
*
~,M)ollf Anc:llwoliJ'IChUft'fC'flif .... .... _
s...~ ...... ,.,, ., ~0 ~ltld
hOM~ ~:t~Jta.. H.letlwtft Qlllt
-.nt:rtf"o-ttaQf,
VOI~C...N'I"l
O....lft"t"'ff'V --~ ~tltf, W"f 01 cont.
1----------l l~of~,
,.OTESc
A.n1-FMI4t-.-t.u~lllll « .,........,""' ....... l"''.-t MMtt 0t '* tn...,..,R
to Of'WM HOii::la'f"'' QP ~fM'N'O w<l•~i;'f
(.-.ot•.otv ~"• a.,t _.,.._,,""" Milt OP'It'f""•"•'""""''
Ot • ~,.,....... ,..,... ,. •• ......, 00 .,.. •• floof.
~~ ,:..,,,-.---~• Ot ......,.tl'llll' ,....., tftM clolrJ not.,,..
H~ I"'IOt ~-d.J ... Vdt,....,.tl 1/lsON..OV
·~ biwf-IPiCIIIIolf Ill'¥ -~IOI'Ii 1'101' II
ft hDONCI «M ..... liOOf .
-,.. .. ~--....... Wrottd ~...-0\are.
21 n z~ ~o Na•hul wtt ..
25 0 21 ~0 tOO "d•••t•'•
Z' 0 Z' ~0 SU:t•tt Wllee
A
Source:
·Woodward Clyde Consultants, 1978, Offshore
Alaska Seismic Exposure Study
BRAOU:Y LAKE HYDROELECTRIC PROJeCT
ALASKA POWI:Jit AUTHORITY
SOUTHERN AI.ASKA REGIONAL FAULTS
ITOICI. a> WUIT'DI
INOIMUII-COIU'OU,notl FIGURE 7
GEOTECHNICAL INTERPRETIVE
REPORT
FIGURE E-21
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NOTE: ELEVATIONS SHOWN ARE BASED ON PROJECT DATUM •
MEAN SEA LEVEL DATUM • PROJECT DATUM • 4.02 FEET.
0 40
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LEGEND
i ARGIL.UTE
GRAYWACKE
ARGILLITE AND GRAYWACKE
(2~'1o OR MORE OF EAC>4J
MAPPED OUTCROP
-----LITHOLOGIC CONTACT
(AI'PRQl(I-TELY LOCAT£01
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ANO NUMBER
LINEAMENT REFERENCE
NUMBER <~E TEXT)
MAIN DAM AREA GEOLOGY
Fl GURE 25
GEOTECHNICAL INTERPRETIVE
REPORT
FIGURE E-23
~
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w/~><~2tOJ
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TABLE 1
HOLE INCLINATI()H F'ACM vERTICAL
STATIOH fi'Oli>CT I OI'IOITATION Cllt 1N1"Ell"'AI.
STA 1·to TO
POINT EH
I'04HT ED
POINT £tt tO ss.s. ~0
lO" ~ vt:JITICAL
INCLINE \,PSTR~
CSCIVTH)
,....nl.D~O
4'!1* ~F' ~ATICALt
N:l. NJ) IN'lO JIIGH
.tBUTMEH1 !EAST
ARE IA101<"~7EO ON P.LA N
IECHTEL
SAN FRANCISCO
ALASKA ENERGY AUTHORITY
A-. .. or•••• Al11ka
BRADLEY LAKE HYDROELECTRIC PRO
IIJ
MAIN DAM
DRILLING & GRCXJTING
PLAN & PROFILE ....... ..........
17707 FIGURE 6-3
FIGURE E-24
...
~ ,....
'-l
d
~ /.
.., " .... trj
I
N
til
• ( I
tnl ~I ... ,Ill
r/1 -"'I'D' ~I • -TO~ ()r; R('\("K -··
111'1 .... 0 ... ~I I
:! -< ~~ ·{ ;I 111'1.(
~I
NOTE.S ~
01
0'1 • ~I
-c(
~
11'1
HOLf C'f ~ T II
P2 HOLE OEP TH
P1 HOLE OfPTft
;r
11:\tl«l~l
I ' I I I
~ ' L-..l"
HOlE DEPTH
LAR6E.R. GROUT TAKE..S /INIJ LOCATtOII/..5 CIRCLED ON PROFILE.
GROUT TAKt::..S RAN<lE FOR f{E/IIfAINDE.R. OF HOLE. S
NUMBE.If QF HOLE 5
~
z..q
2.2.
G~-<ou T TA K E:.S
w-30
I - 5
<.I
IY_JJ
I I
~
• 01
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~ 'QlJ I 1,._...:..... IIIli
Y' I l ' 1---,.,o
I I I . ~llloO
I I I .1 ,.......-JD 1.:::5~ ,,o;o
IIOITIL
SAN FRANCISCO
ALAIICA ENERGY AUTHORITY ...... , ............
BRADLEY
MAIN DAM SPILLWAY
DRILLING&. GAOJTING PROFILE
II ---
FIG.G-6
i'J!j
"""" ~
~
t;1
N
<::1'1
2.25 -Ol -C'1l
Vl1.88
z
0
~1.50 a::. w
_j w u 1.13
~
...J
<( 0.75 a::.
t-w Bl 0.38
0.00
RESPONSE SPECTRUM
FOR HYBRID EARTHQUAKE
-~-··~-
BRADLEY LAKE HYDROELECTRIC PROJECT
MEAN RESPONSE SPECTRUM FOR MCE
(NEARBY SHALLOW CRUSTAL FAULT)
-
REF: WOODWARD-CLYDE CONSULT
REPORT1 "DESIGN EARTHQUAKE STUDv'
NOV ID ,1981
SPECTRUM -
o.oo 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00 2.25 2.50 2.75 3.00
PERIOD (SEC}
MCE RESPONSE SPECTRA-
MEAN AND CHOSEN
~ .....
C")
~
~
M
I
N
-....l
BradleyJ
lake
Surface
Bradley lake
...... ./ /'
I f220\
I ) I I ..._./
I ,/' AdJusted
,.,--,(' Middle Fork
(214 J
'-.../
Sign Change
(a) BRADLEY RIVER
Middle Fork
Glacial
Bands
LEGEND
Wolverine Glacial Bands
Wolverine Creek
near Lawing
(observed)
8
(b)WOLVERINE CREEK
0
0
D
BASIN OR SUBBASIN
COllECT POINT
RESERVOIR SCHEMATIC OF
SSARR MODEL
"%j
"""' Gi
Cj
~
~
N
00
FLU11 CFS 10 AlJI.i 56 1200 11 AUG 56 1200 12 AUG 58 1200 11 AUt> sa 1200 14 AUG 58 1200 15 AUG 58 1200 1& AUG 56 1200 17 AUG 58 1200 18 AUt> 58 1200 19 AUG 58 1200 20 AUG ';;8 1200 FLOw CFS 8 SEP &1 1200 9 SEP &1 1200
10 SEP &1 11?00
11 SEP &1 1200
12 SEf» bl 1200
U SEP 61 1200
14 SEP b1 1200
IS SEP &1 1200
lo SEP bl 1200
17 SEP ol 1200
FLOI'i CFS
10 SEP &o 1200
11 SEP && 1200
12 SEP bb 1200
13 SEP ob 1200
14 SEP bo 1200
15 SEP ob 1200
lo Sf:.P bb 1200
17 SEP &b 1200
18 SEP && 1200
19 SEP bb 1200
20 S!:P bb 1200
21 SEP ob 1200
22 SEP bb 1200
21 SEP bb 1200
24 SEP bb 1200
25 SEP b& 1200
cb st:::P &o 1200
27 SEP bb 1200
28 SEP &o 1200
29 SEP &o 1200
:SO SEP bb 1200
m
:0 :0 > m c cno
r-""o
m sao z -< en :o en -4 -0)=4 < ,c m r-4 :o o-
z o 0
m cz
>en o
:0 , ,
:I: 0 ..... o:oco s: 01 m !»
:0
o. bOO. o.o 10.00 -----......... . . --:---&' o. " bOO. o.o 10.00 6-...----:.
o. bOO.
o.o 10.00 --
PLOT SIATlON NA~l C~ARAC TER C•FLO~ Af b~AOLEY LA~E --CALCuLATED A•FLO~ AT ~~ADLEY LAKE •• UBSE.RVEO lcOO. 1800. 2400, 3000. l&OO. T 20.00 30.00 40.00 so.oo bO,OO . ---·---------. --.e-__., __.. --• _c---/-,.e"" • o'" • T T • r PL~l STAIIUN NAME CHAkACIEH C•FLUw AT A•fLOi'i AT 1200. 1800, T 20,110 30.00 ~RAOL[Y LAKE --CALCULATED ~RADLEY LA~E •• OBSERVED c400, 3000. 3bOO, '10.00 so.oo bO,OO T •
PLOf STATION NAME
CHARACTER
C•fLOW AT SRAOLEY LAKt •• CALCULATEO
A•FLUW AT BRADL~Y LAKE •• OBSE~VEO
1200. 1800, 2400. 3000. 3&00.
T
20.00 :su.oo 40,00 so.oo 60,00
T .
T •
--=--c..... . -T
. -. . T
-:c-T
. . . ' I I' '~' • • .T r--~C
......c---:..-c--:-y-c--:--• T • . T
• 1
• • • 1 •
....., • • I ...........,.. T ,
.r
1
T STATION NUMBER CJ:'-4TROL 4200. -3&&5 70.00 " . . 10.0 Q 10.5 ;I 41\00. 4 100. 8o.oo STAT IUN NUMbER c:.PHROL 4200. •.Sb&S 10.00 10.0 Q 10.5 Q 4800. 4 100. 80.oo
STAT 1 01~·
NUMBER CONTROL
4200.
•36&5
10.00
•
10.0 Q
10.5 Q
4800.
4 100.
8o.oo
51100. 90,00 5400. 90,00
5400.
90.00
&ooo. 100.00 bOOO. 100.00
&000.
100.00
~
~
~
d
~
M
I
N
~
FLOw CFS 1 ALG TZfl200 2 AI.!G 7Q 1200 3 A~G 7ll 1200 Q AUG 7ll 1200 -5 AUG 7ll 1200 6 A~G 7Q 1200 7 AUG 7Q 1200 8 A~G 7ll 1200 9 AI.!G 7Q 1200 10 Al!G 71.1 1200 11 AUG 7Q 1200 12 AUG 7ll 1200 1Q AUG 71.1 1200 15 AUG 7ll 1200 1b AUG 7Q 1200 17 AUG 74 1200 7Q 1200 7Q 1200
24 Al!G 71.1 1200
26 Al!G 71.1 1200
!8 ~tJO 7.11 l2D~
30 AUG 7ll 1200
1 SEP 71.1 1200
74 1200
7ll 1200
5 SEP 7ll 1200
6 SEP 7/J lc:OO
7 SEP 71.1 1200
74 12
11.1 1200
11.1 1200
11.1 1200
00
13 SEP 71.1 1200
7/J 1c:OO
15 SEP 71.1 1200
SEP 7/J 1200
17 SEP 71.1 1200
SEP 74 1200
19 SEP 71.1 1200
0 SEP 74 1200
21 SEP 71.1 1200
22 SEP 71.1 1200
23 SEP 71.1 1200
24 SEP 71.1 1200
25 SEP 71.1 1200
26 SEP 71.1 1200
27 SEP 7ll 1200
28 SEP 71.1 1200
29 SEP 7ll 1200
~n &..;.CO '7t1 1~0U
::0 =: ..... m
zOcoo
mr"""O )><~Z
:om'Ticn :or -I
rzo=i >moe ~ocj
Z:O'T10 G>moz
~::00
'TI
o. 20.00 o.o p p . p p p p p . p p p p p p p p p p p p p
p
p p--
• p
p
,
p
p
p
p
• p
p
• p
p
p
p . .
• . p . . . . . . p . . p
• p .
. p .
• p
p
p
p
PLOT sTATioN N~P.E STATION CHARACTE11 ~Ut-'BER CO~TROL C-WOLVERINE CREEK FLO~ --C~LCLLATED 11 0. 0 c A-WOLVEkiNE CkEEK FLO~ --ceSE~vED 110.~ Q 100. 200. 300. QOO. soo. 600. 700. 800. T -2 36'~ 4 11 0. 26.00 32.00 38.00 llli.OO so.co SE:.OO b2.00 be.oo .., 0.50 1.00 1.50 2.~0 ::!.00 ::! .•5 0 L~.oo • • . . • • . . 1 • . • . . . ~ . . T • • . . • T . • • . . • . . • T • . . . • . • . • . T • . . • ~---. • T . • • . . . -~ . . T • . . . . . { J . . T . • • . • T • • • . . • • • ·r • . . . • . .
----------
. ~: .T
• .
• . • T • -.
~ p .• . . . T
-~·-=-s:
• . • . I . I •
• . • . • T •
• I •
• • • ~ • 1 • . . . . 1 . . • . • . . T . . . . -~~-. T
• •
r • . " . . •
• . • . . . . T
• . • . . • . T . •
---p
• • P. I • . • p
.P •
• •
• p •
~-· . -------. --• I I .
• • . p
~ • T . T • . T. -. • . 1
SURrACE-SUOSURFACE SPLIT
I.
5
[ HU 1-EtfffEiEfHfllHHEf-HllJlEHH"H
....
::>
0 .c ..... 1.0 "' .. .c
p " c:
I ..
::>
" ....... ~LU ,.c.. ,-e' ~~0~
a. c: -u 0.5
u .. .... ....
::>
r.' ac.\ll'
Vl
0
0 0.5 1.1 1.5 z.o
Surface & Subsurface Input-Inches/hour
EVAPOTRANSPIRATIO~ INDEX
,.., .. ., .....
"' .,
"f&_· a.iim. .. . .... 1 .
.10 I Hi tHiiiittH-1 t111-titHttiil·l ~H+t:1
.c u c: -H-+1-H-H-1-1-f-U: G 1 a c i a 1
I c:
-~ ~ ...
~ ..
C')
....
0
0.
.oslllllllll H+H H 111111111++-t-t-t-1-1-++++-1
~ ... >
~ "-'
M O I I I I I I I I I I I I I I I I I I I I I I I Ulilll J1 I I I !]
I
(,H J F H A H J J A S 0 N 0 = l~onth~
SOIL MOISTURE INOEX
~ c .,
u
.... .,
~ so
~ ~
0 §
~
s 10 IS
Soli Moisture Index-Inches
... ... BASEFLOW INFILTRATIOII INDEX 0 c ,.
~
~ 100 1t:tt±t ~ IJl tl:: Glacial ,_
~
0
~ c:
~ .... ..
0..
~
s
0 :;: .. 4 • "' .. m
Baseflow lnfllltratton Index
SNOW COVER DEPLETION
ti 100
r
' Glacial u .... .,
~
~
~
<( .,
f .,
>
8
s
0 c:
"'
;:;> .,
I ... .. ., ..... .. .,
.c u c:
I .. .. .. ~ ....
i
II~ -
~ -0~
:9~ 50
i '• Sl 101
Accumulated Runoff In Percent
t£l T RATE INI£1
.10
H++++-Glacial
.05 ttt:m:il'fH't,... \a' 1\,ac. ~ol\
0
0 51 101
Accumulated Runoff In Percent
BASIN CHARACTERISTICS
FOR SSARR MODEL
~ -~
~
M
I
(,H -
~-r-I. I ~~ LIJ D~Ll I I I I I
I I I I
3· ,_ f--
2 5--
~-~
zO
00 2 -o 0--'-
!;t-.... -ii:w
(JO wa::
0:<(
a.::r; ·o a: en ::r:_
<00
I
:>-t-
5-1-
I
1/ 1\ I/
f! I---•.
l-" /
_j_ ----ti l/
lJ_v v ll.
L-·. Jj . 1175' -~.':-~ •• " :f"' l ll'l<IAS
--~--.'-PROBABLE MAX.FLOOO INFLOW(:'II,?OOCI'.!
I
I
\ SPILLWAY DESIGN OISCHARGEI2J',800CFSI
\
If \ \ ·,
IJ r/ I I\ \
~ \
I/ .r MAX. WATER SURFACE EU:V.III90.65 FT;)
II
17 I" ~ \
II -, v j '.._ \,
I -'
r-').; f---r-r-Jz ~ ~, I ~ ""~ R-"" I' i
. !. .• , ljJLU .. ~ PR~riT TIOi ! ""-... r--
i
, ... I'll',.;-tit (I¥ '; 11' I il 14 "
DURATION (DAYS)
PROBABLE MAXIMUM AND SPILLWAY DESIGN FLOODS
I
I
l
195
....
190 ~
z
165 2
~ w
-' 160 w
PROJECT DESIGN FLOOD
"'!'j .....
G1
d
~
~
t.H
N
1"'\ ... w w
Ll. v
z
0 ...
4( > w
.j w
w :...: c
..J
)-w
.j
0
~
CD
1,191
1,190
1,189
1,188
1,187
1,186
1,185
1,184l
1,183
1,182
1,181 I v
1,180
o.ooo
/
SPILLWAY RATING CURVE
BRADLEY LA~E HYDROELECTRIC PROuECT•
/
~ v
/
/ I
I
/ r""'
/
/
/
/
/ v
/ /
... ooo a.ooo 12.000 16,000 20,000 24.000
SPILLWAY DISCHARGE (CFS)
-
-
LOW DENSITY I
POORLY GRADED.
-+---+ WEAK ROUNDED
PARTICLES
ANTICIPATED RANGE-
BRADLEY LAKE MAIN DAM
HIGH DENSITY, WELL
GRADED, STRONG
ANGULAR PARTICLES
ROCK FILL
30~--~----+---~--~----~--+-----~--~
1 2 5 10 20 50 100 200 500
NORMAL PRESSURE
(PSI)
FROM LEPS 1 1970
ROCKFILL FRICTION ANGLES
FIGURE E-33
CIRCLE SLIP SURFACES
USED IN THE DETAILED ANALYSIS
1250
1200
1150
1100
1050
NORMAL MAX
OPER LEVEL
EL 1180.0'
\7
(PMF)
EL 1190.01
\7
~DAM SHELL~
CIRCLE X CENTER Y CENTER
A
8
c
D
E
F
~ s:;:>,c 8
POINT POINT
596.0 1450.0
596.0 1450.0
696.67 1249.33
24.50 2056.50
71.50 1609.33
71 .50 1609.33
MAX
TAILWATER
(PMF)
EL 1077.0'
'\7
1000;-------.------.------.-------~----~------~------~----~------~------.--------.-----~
100 150 200 250 300 350 400 450 500 550 600 650 700
SELECTED SLIDING SURFACES -MAIN DAM
FIGURE E-34
RADIUS
347.13
366.51
213.80
938.17
522.97
550.07
NORMAL
TAILWATER
EL 1061.01
\7
~
"""" C1
~ ..... ,....
~
~
I
~
(Jl
EL 1180
CONDITIONS : Kv = 1b K H
K BEDDING = ;b K ROCKFfLL
BEDDING LAYER = 12 FT HORIZONTAL
D/S BERM IGNORED
FLOW THROUGH DAM WITHOUT FACE
MAX
BEL 1066
\7
NEGLECT
1.00"
CREST
CREST EL 1180
ALL.ERY
G_DRAINS \
NEGLECT APRON
AT EL 1150 a 1160
ASSUMED
GEOMETRY
NEGLECT
APRON
-'-+----1--------~ -----..., EL 113!5
!51.7'
\
\
\
\
SPILLWAY SECTION
NEGLECT UPLIFT
ON APRON
STATIC
SPILLWAY. MODEL
FIGURE E-36
EL 1130
EL 1124
PMF EL 1191' ~-~..U:.:'---oo:::::-----r __ 5 I EST 0 RAW DOWN
EL 1179
WATER SURFACE
CREST EL 1180'
EL 1130'
LOADING DIAGRAM
NOTES:
1. Stability analysis based on gravity method.
Static analysis for Cases 1, 2 and 4.
Finite element analysis for Cases 3 and 5.
2. Loads:
D ~ Dead weight of structure at 145 lbs/cu. ft. (concrete).
EH = Horizontal inertial force due to earthquake
Ev = Vertical inertial force due to earthquake
Hw= Horizontal hydrostatic force
Vw= Vertical hydrostatic force
I = Ice force at 12 kips/lin ft.
HE= Hydrodynamic earthquake force
U = Uplift force
Numeral subscript indicates load case
3. Load Cases:
Case 1 -Normal
A. -Dead weight
B. -Hydrostatic forces for normal maximum reservoir
level of El 1180'
C.-Ice
D.-Uplift and seepage forces
Case 2 -Probable maximum flood IPMF)
A. -Dead weight
B. -Hydrostatic forces for maximum reservoir level
of El 1190.6'(rounded up to 1191')
C. -Uplift and seepage forces
Case 3 -Earthquake
A.-Dead weight
Case 4 -Construction
A. -Dead weight
B.-1) Earthquake inertial forces for operational basis
earthquake 10.1 g horizontal) or;
2) Wind
Case 5 -Low reservoir level earthquake
A. -Deed weight
B.-Earthquake inertial forces for maximum credible
earthquake (0.75g horizontal & O.Sg vertical)
4. Base pressures for Case 3 and Case 5 determined by two
dimensional finite element analysis with earthquake inertia
load computed from response spectrum analysis and hydro-
dynamic effects approximated by Westergaard added masses.
5. Uplift pressures assume a drain efficiency of 50% at the base.
6. Uplift assumed to act over 100% of base area.
7. Base pressures for uncracked sections calculated without in-
cluding uplift as an active external force. Uplift pressures were
combined with the resulting base pressures by the superposition
method.
8. Allowable stress in PSI:
Concrete (3000 PSI) Rock I40KSF = 280 PSI)
Tension Compression Compression
Case 1 60 1000 140
Case 2 90 1500 185
Case 3 270 3000 250
Case 4 90 1500 185
Case 5 270 3000 250
B.-Hydrostatic forces for normal maximum reservoir 9. Sliding factor of safety for Cases 1, 2 and 4 is based on shear
level of El 1180' friction factor of safety formula with 160 PSI cohesion and
C. -Ice an internal angle of friction of 45 degrees
D. -Earthquake inertial and hydrodynamic forces for
maximum credible earthquake (0.75g horizontal
& O.Sg vertical)
E.-Uplift and seepage forces
SPILLWAY
ANALYSIS
STABILITY
SUMMARY
FIGURE E-37
CASE I -NORMAL RESERVOIR
RESULTANT PRESSURES INCLUDING UPLIFT
(psi)
\7 WS EL 1180
EL 1175
3.6 psi
TENSION
EL 1160
1.1 psi
TENSION
EL 1150
3.2 psi
EL 1140
l~psi ·
16pai
NOTE:
GALLERY SLAB ISOLATED FROM STRUCTURE
SO WILL NOT PROVIDE RESISTANCE. SLAB
DEBONDED FROM ROCK SO ACTUAL UPUFT
WILL BE NEGLIBILE (TYP),
STATIC ANALYSIS
BASE EL 1124
FIGURE E-38
CASE IT-PMF
RESULTANT PRESSURES INCLUDING UPLIFT
(psi)
'g WS EL 1191
EL 1180
0.3 pai
EL 1170
0.9 pai
EL 1160
I. 4 psi
EL 1150
3.4 pai
EL 1140
I !5 pai
EL 1135
II psi
EL 1124
I
} CREST
I
STATIC ANALYSIS
BASE EL 1124
FIGURE E-39
CASE BZ-CONSTRUCTION
( 0.1 g HORIZ )
RESULTANT PRESSURES
(psi)
CREST
EL 1180
EL 1170
9.6 psi
EL 1160
18.5 psi
EL 1150
27.1 psi
EL 1140
4:5 psi
EL 1135
48pai
GROUND
ACCELERATION
STATIC ANALYSIS
BASE EL 1124
FIGURE E-40
STATIC STABILITY RESULTS
BASE PRESSURE DIAGRAMS
EL 1124
CASE I
NORMAL
. . ,
CASE 2
PMF
. . ,
CASE 4
CONSTRUCTION
CASE RESULTANT KIPS X
. . ...
4o.
• lr • •
BASE EL 1124
BASE PRESSURE ·PSI SAFETY
1111/UPLIFT 1111/0 UPLIFT FACTOR
CRACK
LENGTH
BASE PRESSURE DIAGRAMS
EL 1135
... +t' t j
ttJtt t j
lY
CASE
BASE PRESSURE DIAGRAMS
EL 1150
DDJ
DCD
~ [J7 v
BASE EL 1150
BASE PRESSURE • PSI
RESULTANT KIPS X 1111/UPLIFT 1111/0 UPLIFT
NUMBER Ev l:H FT UIS D/S UIS DIS SLIDING FEET NUMBER Ev l:H FT U/S DIS UIS DIS
1 237 110 :'15.5 10 32 34 34 17.0 0 1 76 40 19.1 10 22 23 22
2 222 136 34.8 4 34 33 36 13.6 0 2 67 49 20.0 9 20 26 20
4 294 32 42.9 47 11 47 11 61.0 0 4 95 10 24.9 37 5 37 5
"
BASE EL 1135 I
BASE PRESSURE· PSI SAFETY CRACK
CASE rESULTANT, KIPS
NUMBER Ev I EH
X 1111/UPLIFT 1111/0 UPLIFT FACTOR LENGTH
FT UIS DIS U/S DIS SLIDING FEET
1 I 126 I 75 28.9 16 26 35 28 17.2 0
2 I 137 I 94 28.7 11 26 35 29 13.8 0
4 198 21 35.5 48 8 48 8 64.3 0
SAFETY
FACTOR
SLIDING
21.6
17.6
86.6
I
CASE
lNUMBER
1
2
4
BASE PRESSURE DIAGRAMS
EL 1160
OU]
om
DUJ
1
CRACK
LENGTH
FEET
0
0
0
BASE EL 1160
BASE PRESSURE ·PSI SAFETY
!RESULTANT KIPS X 1111/UPUFT W/OUPLIFT FACTOR
Ev LH FT U/S DIS U/S D/S SLIDING
31 25 12.3 2 18 11 20 23.0
22 26 14.7 5 13 18 15 21.0
45 5 18.3 23 5 23 5 118
SPILLWAY STABILITY
ANALYSIS SUMMARY
SHEET 2
FIGURE E-41
CRACK
LENGTH
FEET
0
0
0
EL II 4 0
EL II 80 ...._
T l r---....
I 1 1'...
J 1 l [".,_
----~~CO~N~CR~ETE~]J~~~~~/--1-~~~~~---
ROCK I I l / ''t-+-+--t~.:\S::::::l+-.-_,...___.--.---. E L II 63
EL II 6 o : f ] ""~~ .I
I~ 20' 39. 45'
FINITE ELEMENT MODEL
BASE EL 1160
20' ~I
FIGURE E-42
E L 1068
I~
EL 1180 --=...::......:...:....::.:::.--. .,. r--.
1
J
J.
56 I 79'
FINITE ELEMENT MODEL
BASE EL 1124
56' .. I
FIGURE E-43
CASE ill-EARTHQUAKE
(0.75g HORIZ +0.50g VERT)
MAX VERTICAL TENSILE STRESSES W/0 UPLIFT
(PSI)
+45.4 -17.5
+TENSION
-3.4 -COMPRESSION
-22.2 -7.8 ~2.1
-23. a -10 .a -3.1 +1. 4
EL 1160
FINITE ELEMENT ANALYSIS
BASE EL 1160
FIGURE E-44
CASEIIT-EARTHQUAKE
( 0.75 g HORIZ• 0. 50g VERT)
MAX VERTICAL COMPRESSIVE STRESSES W/0 UPLIFT
(PSI)
+TENSION
-6.8 -COMPRESSION
-9.3 -18.3
-36.8 -16.6
-44.4 -22.2 -17.3
FINITE ELEMENT ANALYSIS
BASE EL 1160
FIGURE E-45
-14.0
CASEY -EARTHQUAKE
(0.75g HORIZ +0.50g VERT)
MAX VERTICAL TENSILE STRESSES
(PSI)
CREST EL 1180
+TENSION
-0.1 -COMPRESSION
+0.5 .
+0.8
-3.4 +5.8
EL 1160
-16.5 -4.9 +1.2 +3.9
FINITE ELEMENT ANALYSIS
BASE EL 1160
FIGURE E-46
CASEY -EARTHQUAKE
(0.75g HORIZ +0.50g VERT)
MAX VERTICAL COMPRESSIVE STRESSES
(PSI)
-29.5 -48.4
+TENSION
-3.5 -COMPRESSION
-5.3 .
-11.8
-12.2
-37.1 -16.3 -13.0 -10.1
EL 1160
FINITE ELEMENT ANALYSIS
BASE EL 1160
FIGURE E-47
CASE ill -EARTHQUAKE
(0.75g HORIZ + 0.50g VERT)
MAX VERTICAL TENSILE STRESSES W/0 UPLIFT
. (PSI)
CREST EL 1180
(.~~+o.2
t21.. -0.2 +2~
+30.3 +3.9 +0.2 1.~
+ TENSION
-COMPRESSION
+1!)4 .3 I +36.7 -t~.a -7.~ +13.6 1'\.. ~~~----~---+----+----+k~aa~~
;_, +38.0 +7.1 -10.3 +2.9 ·125.3 ~ ... 9
f. ... +41.2 +3.8 -11.8 -6.0 +9.7 ~ .
1+62.71\tl•-
7 1-1.•/ -9.2 -12.0 +1-6 +23.0 ~ ~ay~~~~---+--+-~~--+---r ........ 1 +741 [:;; , -13.5 -17.0 -!5.9 +8.2 +21.1
I +87.3 I +3.4 '\fl.... -14.4 -21.1 -13.1 -1.6 +8.7
FINITE ELEMENT ANALYSIS
BASE EL 1124
+17.2
-+9.5
+1.4
~
+15.7
FIGURE E-48
EL IIZ4
CASE ill -EARTHQUAKE
(0.75g HORIZ + 0.50g VERT)
MAX VERTICAL COMPRESSIVE STRESSES W/0 UPLIFT
(PSI)
-le.4 -t TENSION
-COMPRESSION
-23.9
-32.0 -24.1
-69.0 -39.3 -27.1 -43.3
-77.6 -33.4 -40A
-40.7 -55.0 -70.6
-53.3 -45.6 -66.2 -63.9 -38.4
. -6 0.2 -50.7 -65.0 -64.1 -48.3
FINITE ELEMENT ANALYSIS
BASE EL 1124
FIGURE E-49
~8.6
CASE V:. -EARTHQUAKE
(0.75g HORIZ + 0.50g VERT)
MAX VERTICAL TENSILE STRESSES
(PSI)
CREST EL II 80
(. ::--~ <6.0
tii.B +1.6 +9~
+21. 8 +3. 6 +5.9 /'\.. ~23.8'\
+ TENSION
-COMPRESSION
+29.3 +4.9 -3.6 +21.3 hT38.3
-t-32.1 +5.9 -7.6 +8.7 +34.7 1\. ~so A
+35.2 +3.1 -10.3 -2.0 +16.6 +~"""
t5e 6 ~ ~:J-.--9_. 7~---9_._3 -+-+-7._8+-+-3_2-.3-+1 +-77-oo .. _ ~6--r--
/ + 68.8 :::;. ' -12.8 -13.6 1-0.2 +16.1 +29.4 -t22.2
+2.3
~----~~----~~----r----r--~----~----+-----~ I +77.5 /+6.2'\r 24"2~e.3 -14.6 -17.5 -7.6 +5.6 +16.2 -+14.9 ~ ~---------·--~&J' __ +------------~------~~--------------~ELII24
FINITE ELEMENT ANALYSIS
BASE EL 1124
FIGURE E-50
CASE -si. -EARTHQUAKE
(0.75g HORIZ -+ 0.50g VERT)
MAX VERTICAL COMPRESSIVE STRESSES
(PSI)
-13.6 ~ TENSION
-COMPRESSION
-48.6 -24.2 -21.1
-32.9 -20.2 -41.7
-74.9 -40.5 -24.4 -37.5
-83.6 -'31.9
-37.5 -48.8 -61.3
-52.6 -42.2 49.2 -58.3 -55.6
-60.4 -47.1 52.0 -57.8 -56.6 -42.9
FINITE ELEMENT ANALYSIS
BASE EL 1124
FIGURE E-51
CREST EL 1180 CENTER OF GRAVITY
ACTUAL OGEE-----... ,
ASSUMED MODEL OF EQUAL
MASS AND CENTER OF
GRAVITY. GEOMETRY
EL 1160
BASE EL1160
CREST EL 1180.0
ACTUAL OGEE~ /'
GEOMETRY ;t' ASSUMED MODEL
I 38.8' ..
BASE EL 1150
SARMA ANALYSIS MODEL
OGEE SECTIONS
SHEET I
EL 1150.0
FIGURE E-52
CREST EL 1180.0
ACTUAL OGEE--ASSUMED MODEL
GEOMETRY
19.1 1
EL 1130
61.8'
BASE EL 1130
CREST EL 1180
ACTUAL OGEE~,
GEOMETRY ;'
---ASSUMED MODEL
I
I
69.0'
BASE EL 1124
SARMA ANALYSIS MODEL
OGEE SECTIONS
SHEET 2
FIGURE E-53
ACTUAL~ NON OVERFLOW
GEOMETRY ,-
1
I
ASSUMED~
MODEL "
EL 1195.0
ACTUAL~,----NONOVERFLOW :
GEOMETRY
EL 1195.0
I CG
I
35.5 1
BASE EL 1160
LEFT ABUTMENT
ASSUMED MODEL OF
EQUAL MASS AND
CENTER OF GRAVITY
EL I 145.0
EL1124.0
EL 1168.0
EL 1160.0
BASE EL 1124
RIGHT ABUTMENT
SARMA ANALYSIS MODEL
NON-OVERFLOW SECTIONS .
FIGURE E-54
APPENDIX F
INSTRUMENTATION DRAWINGS
FIGURE NO.
F-1 HORIZONTAL & VERTICAL CONTROL, 1 OF 2
F-2 HORIZONTAL & VERTICAL CONTROL, 2 OF 2
PAEABL22
I0/12/96
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ANNUAL SURVEY TO DETECT MOVEMENT
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DATA 1992 199J 1993 1994 7995
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NOTES:
1. EU:VJ.TTONS ARE BASED ON BR.IJ)lZY LAKE PROJECT DATUJI. J/ONUJIENTS SP-P..A THROUGH SP-2}( ARE BASED ON BENCH JIAR]( "VENUs".
THE TOP OF NUT ON ts/8" STAINLESS STEEL BOLT IN ROCK 0 APPROXlA/ATELl' 30' RJGJn OF STATION 2+20 JLAIN DAJI BASELINE
(E:U:VATION 1179.942 AS SHO'IfN ON "JiAIN DAJI AREA SURVEY JIONUlfENTATIOJY, POWER AUTHORITY DJU.Jf!NG NO. H05-F-11-0012-R49).
2. EU:VATTONS OF MONUMENTS SP-3A '!'HROUGH SP-3C ARE BASED ON BJI 90-05-19, DESCR1BED AS: TOP OF NUT ON 5/8" STAINLESS
STEEL BOLT IN ROCK AT APPROXDIATELY 220' u:rr OF STATTON 8+00 JlAJN DAJ/ BASEIJNE. EI.EV.-1080.657 (JIAD{ DAJI AREA SURVEY
J/ONUJ.lENTA TION).
3. MONUMENT GRAPH P05mON 0.0 IS ESTABUSHED FROJI JIONUJIENT VALUES SHOWN ON "JIAJN DAJI ARU SURVEY JIONUJ/ENTATTON"
POWER AUTHORITY DRAWING NO. H05-F-08-0037-R49.
4. ALL STATION AND OFFSET CALCULATIONS ARE REFERENCED FROJI THE 'JIAIN DAJI IJASEI.I1ir (P.RDI.ARY CONTROL JIONUJIENT 4 [PCJI-4)
TO PCJI-2) WITH PCM-4 AS THE BASIS OF STATIONING.
5. POWER AUTHORITY DRAWING NO. H05-F-08-0037-R49 INCORRECTLY USTS ST..tTTON!NG OF PCJI-4 AS 10+43.354. THE 1992 DEFLECTION
SURVEY ASSUJIES THE PCJI-4 STATION AS 0-43.353. DETERMINED BY SUBTRACTING THE HORIZONTAL INVERSE DISTANCE OF COORDINATE
VALUES SHOWN FOR PCJI-4 TO PCJI-2 (1258.716), FROJI THE STATIONING SHOWN FOR PCJI-2 (12+15.383 ON POWER AUTHORITY DJUWING
NO. H05-F-08-0037-R49}.
6. 1992 DEnECTJON SURVEY JIEASURED .AU. JIONUJIENTS ON SEPTEJIBER 21. JfJTH A LAKE SURFACE ELEVATION OF 1148.~. EXCEPTING
SPILLWAY JIONVMENTS SP-2J AND SP-2K JrHJCH WERE SURVEYED NOVEJIBER 13. 1992 WITH A LAKE SURFACE ELEVATION OF 1140.1 .
7. THESE SURVEYS USE THE CENTER OF A STAJII'ED •o• ON THE TOP (OFFCENTER) OF 5/8" ST.AINLESS BOLTS FOR SPILLWAY JIONUJIENTS
SP-2J AND SP-2K. ON SP-2J THE CEN'I'ER OF THE "()" IS OFFSET .005 LEFT OF '!'HE BOLr CENTER .AND .005 DOWNS1'ATION OF THE
BOLT CENTER. ON SP-2K THE CENTER OF THE ·o· IS OFFSET .004 LEFT OF THE BOLT CENTER .AND .000 (NO) STATIONING DIFFERENCE.
8. ELEVATION OF POINTS NOT LOCATED ON THE DAJI ARE DESIGNATED AS NOT APPUCABLE.
9. ORIGINAL STATION SHOWN FOR A/ONUJIENT SP-2H IS SHOWN AS 9+29.962. 1992 SURVEY VALUE IS 9+29.926. ORIGINAL STATION SHOWN JlAY
HAVE BEEN A TR.ANSPOSJTJON OF NUMBERS.
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BRADLEY LAKE DAM
FIGURE F-2
SHEET NO.
2
OF
2
HJa.OfiC
PAEABL24
10/12196
APPENDIX G
PHOTOGRAPHS
AERIAL VIEW-DAM AND SPILLWAY
AERIAL VIEW -RIGHT ABUTMENT, SPILLWAY, RESERVOIROUTLET
SHAFT HOUSE AND DOWNSTREAM PORTAL STRUCTURE
1
UPSTREAM FACE OF DAM FROM RIGHT ABUTMENT
UPSTREAM FACE OF DAM FROM LEFT ABUTMENT
2
LEFT ABUTMENT PLINTH JOINT W ATERSTOP
RIGHT ABUTMENT PLINTH AND TRANSITION JOINT W ATERSTOPS
3
UPSTREAM FACING APPROXIMATE MIDDLE OF DAM. NOTE
SHRINKAGE VERTICAL AND HORIZONTAL CRACKING
CREST ALONG DOWNSTREAM SIDE
4
DOWNSTREAM RIP-RAP FACING ZONE
DOWNSTREAM TOE ACCESS ROAD TO RESERVOIR OUTLET PORTAL
STRUCTURE
5
I
SPILLWAY FROM THE LEFT SIDE
SPILLWAY LEFT NON-OVERPOUR SECTION. ACCESS DOOR IS TO
DRAINAGE GALLERY.
6
GENERAL VIEW OF POWERHOUSE
SPILLWAY IDGH
OGEE SECTION.
NOTE CRACKS WITH
CALCITE EVIDENCE
OF LEAKAGE .
7