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FINAL SUPPORTING DESIGN REPORT
SITE PREPARATION CONTRACT
BRADLEY LAKE
HYDROELECTRIC PROJECT
FEDERAL ENERGY REGULATORY COMMISSION
PROJECT NO. P-8221-000
VOWME 1
REPORT
Prepared By
STONE & WEBSTER ENGINEERING CORPORATION
ANCHORAGE, ALASKA
March, 1986
Alaska Power Authority
FINAL SUPPORTING DESIGN REPORT
SITE PREPARATION CONTRACT
BRADLEY LAKE
HYDROELECTRIC PROJECT
FEDERAL ENERGY REGULATORY COMMISSION
PROJECT NO. P-8221-000
VOLUME 1
REPORT
Prepared By
STONE & WEBSTER ENGINEERING CORPORATION
ANCHORAGE. ALASKA
March. 1986
TABLE OF CONTENTS
TABLE OF CONTENTS
FINAL SUPPORTING DESIGN REPORT
SITE PREPARATION CONTRACT
VOLUME 1
REPORT
1.0 INTRODUCTION
2.0 DESIGN AND GENERAL TECHNICAL DATA
2.1 DESIGN
2.2 DESIGN LOADS
2.3 STABILITY CRITERIA
I
3.0 SUITABILITY ASSESSMENT
3.1 SPECIFIC ASSESSMENTS
3.2 EXECUTIVE SUMMARY OF FINAL SITE CONDITIONS REPORT
4.0 BORINGS, GEOLOGICAL REPORTS, AND LABORATORY TEST
REPORTS
5.0 BORROW AREAS AND QUARRY SITES
5.1 BORROW AREA LOCATION
5.2 BORROW QUANTITIES
5.3 QUARRY SITES
6.0 STABILITY AND STRESS ANALYSIS
6.1 GENERAL
6.2 DIVERSION TUNNEL INCLUDING INTAKE
6.3 DOWNSTREAM CHANNEL IMPROVEMENT
6.4 MAIN DAM
6. 5 SPILLWAY
6.6 MIDDLE FORK DIVERSION DAM
6.7 POWERHOUSE
6.8 REFERENCES
7.0 BASIS FOR SEISMIC LOADING
7.1 GENERAL
7.2 SEISMOTECTONIC SETTING
7.3 SEISMIC DESIGN
8.0 SPILLWAY DESIGN FLOOD BASIS
8.1 STUDY METHODOLOGY
8.2 MODEL CALIBRATION
8.3 PROBABLE MAXIMUM FLOODS
8.4 STANDARD PROJECT FLOOD
8.5 SPILLWAY DESIGN FLOOD
2-379-JJ
i
TABLE OF CONTENTS (Continued)
FINAL SUPPORTING DESIGN REPORT
SITE PREPARATION CONTRACT
VOLUME 1
REPORT
9.0 BOARD OF CONSULTANTS
9.1 INDEPENDENT BOARD OF CONSULTANTS
9.3 FERC BOARD OF CONSULTANTS
ii
2-379-JJ
TABLE OF CONTENTS (Continued)
FINAL SUPPORTING DESIGN REPORT
SITE PREPARATION CONTRACT
VOLUME 1
REPORT
APPENDIX A DRAWINGS
Plate Title
Exhibit F
1 General Plan
2 General Arrangement -Dam, Spillway and Flow Structures
3 Concrete Faced Rockfill Dam -Sections and Details
4 Spillway -Plan, Elevations and Sections
5 Power Conduit Profile and Details
6 Intake Channel and Power Tunnel Gate Shaft -Sections and
Details
7 Site Preparation Excavation at Powerhouse -Plan
8 Site Preparation Excavation at Powerhouse -Elevations
9 90 MW Pelton Powerhouse -Elevation
10 Construction Diversion -Sections and Details
11 Middle Fork Diversion -Plan and Profile
12 Middle Fork Diversion -Elevation and Details
13 Main Dam Diversion -Channel Improvements
14 General Arrangement -Permanent Camp and Powerhouse
15 Barge Dock
16 Powerhouse Substation and Bradley Junction
17 Main One Line Diagram
18 Martin River Borrow Area
19 Waterfowl Nesting Area
Figures
F.6.2-5
F.6.2-6
2-379-JJ
Mean Horizontal Response Spectrum
Design Accelerogram
iii
TABLE OF CONTENTS (Continued)
FINAL SUPPORTING DESIGN REPORT
SITE PREPARATION CONTRACT
VOLUME 1
REPORT
APPENDIX B LIST OF ATTACHMENTS
B.1 Construction Schedule Contract Dates
B.2 Independent Board of Consultant's Meetings:
Meeting No. 1 May 12 and 13, 1983
Meeting No. 2 July 11 to 15, 1983
Meeting No. 3 September 25 to 27, 1984
Meeting No. 4 November 4 and 5, 1985
Meeting No. 5 January 28, 1986
B.3 FERC Board of Consultant's Meeting:
Meeting No. 1 March 6 and 7, 1986
APPENDIX C
The Final Site Conditions Report of Geotechnical Field
Investigation for Bradley Lake Hydroelectric Project -1984 and
1985 Programs is included with this report.
iv
2-379-JJ
TABLE OF CONTENTS (Continued)
FINAL SUPPORTING DESIGN REPORT
SITE PREPARATION CONTRACT
VOLUME 2
DESIGN CRITERIA
1.0 Design Criteria for Civil Structures:
1.2 Permanent Access Road
1.3 Permanent Bridges
1.4 Borrow Areas
1. 5 Barge Dock
1.6 Airstrip
1.7 Temporary and Permanent Camps
2.0 Geotechnical Design Criteria -Site Preparation
3.0 Structural Design Criteria -Main Dam Diversion
4.0 Hydraulic Design Criteria -Main Dam Diversion
v
2-379-JJ
TABLE OF CONTENTS (Continued)
FINAL SUPPORTING DESIGN REPORT
SITE PREPARATION CONTRACT
VOLUME 3
CALCULATIONS
Title
GEOTECHNICAL
1.
2.
3.
4.
5.
6.
7.
8.
9.
HYDRAULIC
1.
2.
3.
2-379-JJ
Main Dam Diversion
Tunnel Alignment and Surface Excavation
Stability of Diversion Tunnel Portals
Design of Rock Reinforcement
Support System for Main Dam Diversion
Tunnel
Gabion Stability
Diversion Channel
Alignment and Excavation
Stability of Temporary Rock
Plug for Main Dam Diversion Tunnel
Powerhouse Benching Plan and Surface
Excavation
COE/BLHP Survey Datum
Correlation -Damsite
Rock Engineering/Design Criteria
Parameters
Design Channel Size Downstream of
Diversion Tunnel
Quantities of Excavation and Comparison
of Quantities for Various Depth of Channel
Quantities of Cofferdams
vi
Calculation
No.
G(A)-03
G(A)-07
G(A)-09
G(A)-14
G(A)-15
G(A)-17
G(A)-18
G(H)-19
G(A)-21
H-003
H-004
H-008
TABLE OF CONTENTS (Continued)
FINAL SUPPORTING DESIGN REPORT
SITE PREPARATION CONTRACT
VOLUME 4
CALCULATIONS
Title
HYDRAULIC (Continued)
4.
5.
6.
7.
8.
9.
Water Surface Profile in Diversion Tunnel
Fish By-Pass Pipe System
Forcing Frequency for Diversion Intake Pier
Lake Drawdown
Design of Channel Downstream of Diversion
Tunnel
Water Surface Profiles Downstream of
Diversion Tunnel
10. Bulkhead Gate Operation
Diversion Tunnel
11. Water Surface Profile Diversion Tunnel
12. Riprap Design -Bank Across Pool from
Diversion Tunnel
13. Relationship of USGS Gaging Stations to
Bradley Lake Project Datum
14. Synthesize Flood of Record Inflow
Hydrograph from Recorded Outflow Hydrograph
at Bradley Lake
15. Flood Routing Flood of Record through
Bradley Lake and Diversion Tunnel
vii
2-379-JJ
Calculation
No.
H-010
H-012
H-014
H-015
H-016
H-017
H-018
H-019
H-021
H-024
H-029
H-033
STRUCTURAL
1.
2.
3.
4.
2-379-JJ
TABLE OF CONTENTS (Continued)
FINAL SUPPORTING DESIGN REPORT
SITE PREPARATION CONTRACT
VOLUME 4
CALCULATIONS
Title
Wind Loads for Design Criteria
Snow and Ice Loads for Design Criteria
Main Dam Diversion -Intake Portal
Analysis and Design
Main Dam Diversion -Intake Bulkheads
viii
Calculation
No.
SDC-1
SDC-2
SC-131-1
SS-132-2
INTRODUCTION
1.0 INTRODUCTION
As part of the documents for the Application for License for the
Bradley Lake Hydroelectric Project, the Applicant issued a "Preliminary
Supporting Design Report." In that document the Applicant stated that
a "Final Design Report'• would be submitted to the Commission for review
and approval prior to the award of the construction contracts.
There will be three major construction contracts awarded for project
facilities. The scheduled dates for the submittal of Final Supporting
Design Reports for each phase to the Commission for approval and the
dates for starting each phase of construction are shown on Scheduled
Contract Dates Appendix B (Attachment 1). The three phases of
construction consist of:
First Phase -Site Preparation Contract
o Clearing, grubbing and removing overburden in diversion
structure, camp, road, and powerhouse areas
o Rock excavation
o Construction of access road and bridges to permanent
facilities and Martin River borrow area
o Quarry and placing riprap
o Site grading and stockpiling topsoil
o Diversion tunnel excavation
o Placing concrete and reinforcing steel for the intake
structure of the diversion tunnel
o Construction of the temporary and permanent camp facilities
including utilities
o Construction of the airstrip
o Construction of the barge dock including sheet pile cells,
approach roads and local dredging
o Placing rock bolts and slope protection in powerhouse and
diversion tunnel excavations
o Improvement of channel downstream of diversion tunnel outlet
2-379-JJ 1-1
0 Installation of communication
damsite power supply cable
service microwave and light
installed)
tower power supply and main
and install television/phone
fiber optic cables. (Owner
Second Phase -Civil Construction Contract
o Construction of diversion outlet structure and gate shaft
o Completion of the concrete and steel lining of the diversion
tunnel
o Excavation of the power tunnel
o Construction of the power tunnel concrete and steel lining
including intake and vertical gate shaft
o Installation of the power penstock
o Rock excavation for all permanent structures including
tailrace channel
o Construction of the dam, spillway and cofferdams
o Construction of the powerhouse including installation of
equipment
o Construction of the Nuka Diversion
o Construction of the Middle Fork Diversion
o Construction of the Substation
o Electrical work in all permanent facilities except for that
installed as part of the Site Preparation Contract
Third Phase -Transmission Contract
o Construct transmission line
o Construct Bradley Junction transmission line intertie
This final supporting design report for the Site Preparation Contract
is submitted by the Applicant to demonstrate that the work proposed
under the Site Preparation Contract is safe and adequate to fulfill
their stated functions.
2-379-JJ 1-2
The revised Exhibit F drawings for the First Phase Site Preparation
Contract are included herein. Also some revised Exhibit F drawings for
the Civil and Transmission contract are furnished, but will be further
revised and resubmitted with the Civil Construction Contract Final
Supporting Design Report. Second and Third Phase Final Exhibit F
drawings and Final Supporting Design Report will be submitted by the
Applicant for Commission approval in January 1987 prior to bidding the
Civil Construction Contract.
Unless otherwise noted. all elevations given in this report are based
on Project datum.
The Boring Logs. Geological Reports and Laboratory Test Reports were
included in the Appendices in Volumes 5 through 10 of the License
Application for the Bradley Lake Hydroelectric Project. The titles of
these reports and the Appendix references are listed in Section 4.0.
The "Final Site Conditions Report of Geotechnical Field Investigations
1984 and 1985 Programs" is included with this report as Appendix C.
2-379-JJ 1-3
DESIGN AND GENERAL
TECHNICAL DATA
2.0 DESIGN AND GENERAL TECHNICAL DATA
2.1 DESIGN
The following design data are furnished to indicate to the Commission
staff the applicable codes, guides, regulations, and standards which
are utilized in the engineering and design of the documents required
for the Bradley Lake Hydroelectric Project. Attached to this report
are the Design Criteria that are the basis of the design of the Site
Preparation Contract structures as listed below:
0 Permanent Access Road
0 Haul Road Bridges
0 Borrow Areas
0 Barge Dock
0 Airstrip
0 Temporary and Permanent Camps
The Final Supporting Design Report for the Civil Construction Contract
will be submitted for the Commission's approval in January 1987. Final
geotechnical and geological investigations have been completed and the
"Final Site Conditions Report of Geotechnical Field Investigations 1984
and 1985 Programs" is included with this report as Appendix C.
2.1.1 Codes, Guides and Regulations
Where specific standards and design criteria are not covered in these
design data, the latest edition of the following codes and standards
will apply:
2-379-JJ 2-1
2.1.1.1 General
ANSI A58.1
UBC
AAC
ABCC
OSHA-AK
OSHA-US
Minimum Design Loads for Buildings and Other Structures;
American National Standards Institute
Uniform Building Code; International Conference of
Building Officials
Alaska Administrative Code, Section 13AAC50
(incorporates UBC provisions for Alaska Building Code)
Alaska State Building Construction Code
General Safety Code, Vol. I, II, and III, Occupational
Safety and Health Standards, Alaska Department of Labor,
Division of Occupational Safety and Health, 1973 and as
amended in 1983 and the Construction Code, 1974 and as
amended in 1982
u.s. Department of Labor Occupational Safety and Health
Administration, OSHA 2206 General Industry Standards
(29 CFR 1910), and OSHA 2207 Construction Industry
(29 CFR 1926/1910), as supplement to the State of
Alaska's General Safety Code
2.1.1.2 Concrete
ACI 207. 1R
ACI 207.2R
2-379-JJ
Mass Concrete for Dams and Other Massive Structures;
American Concrete Institute
Effect of Restraint, Volume Change, and Reinforcement on
Cracking of Massive Concrete; American Concrete
Institute
2-2
ACI 210R
ACI 211. 1
ACI 214
ACI 301
ACI 302
ACI 306
ACI 315
ACI 318.1
ACI 322
ACI 336.2R
ACI 336.3R
ACI 347
2-379-JJ
Erosion Resistance of Concrete in Hydraulic Structures;
American Concrete Institute
Standard Practice for Selecting Proportions for Normal,
Heavy Weight, and Mass Concrete; American Concrete
Institute
Recommended Practice for Evaluation of Strength Test
Results for Concrete; American Concrete Institute
Specifications for Structural Concrete for Buildings;
American Concrete Institute
Guide to Concrete Floor and Slab Construction
Cold Weather Concreting; American Concrete Institute
Manual of Standard Practice for Detailing Reinforced
Concrete Structures; American Concrete Institute
Building Code Requirements for Structural Plain Concrete
and Commentary; American Concrete Institute
Building Code Requirements for Structural Plain
Concrete; American Concrete Institute
Suggested Design Procedures for Combined Footings and
Mats; American Concrete Institute
Suggested Design Construction Procedures for Pier
Foundations; American Concrete Institute
Recommended Practice for Concrete Formwork; American
Concrete Institute
2-3
ACI 531
ACI 531.1
ASTM C33
ASTM C150
CRD-C119
Building Code Requirements for Concrete Masonry
Structures, and Commentary on Building Code Requirements
for Concrete Masonry Structures; American Concrete
Institute
Specification for Concrete Masonry Construction;
American Concrete Institute
Specification for Concrete Aggregates; American Society
for Testing and Materials
Specification for Portland Cement; American Society for
Testing and Materials
Method of Test for Flat and Elongated Particles in
Coarse Aggregate; U.S. Army, Corps of Engineers
CRSI CRSI Handbook; Concrete Reinforcing Steel Institute
2.1.1. 3 Steel
AISC
AISC
AISC
AISC
2-379-JJ
Manual of Steel Construction; American Institute of
Steel Construction, Inc., 8th Edition
Specification for the Design Fabrication and Erection of
Structural Steel for Buildings with Commentary; American
Institute of Steel Construction
Codes of Standard Practice for Steel Buildings and
Bridges with Commentary; American Institute of Steel
Construction
Specification for Structural Joints Using ASTM A325 and
A490 Bolts
2-4
AISI
ASME VIII
ASTM
AWS Dl.l
AWS Dl.4
AWWA C200
AWWA C206
AWWA C207
AWWA C208
AWWA DlOO
AWWA Dl02
AWWA Mll
2-379-JJ
Specifications for the Design of Cold-Form Steel
Structural Members with Commentary; American Iron and
Steel Institute
Pressure Vessels; American Society of Mechanical
Engineers
Various Standards, American Society for Testing and
Materials
Structural Welding Code; American Welding Society
Reinforcing Steel Welding Code; American Welding Society
Steel Water Pipe 6 Inches and Larger; American Water
Works Association
Standard for Field Welding of Steel Water Pipe; American
Water Works Association
Standard for Steel Pipe Flanges for Waterworks Services
-Sizes 4 in. through 144 in.; American Water Works
Association
Standard for Dimensions for Steel Water Pipe Fittings;
American Water Works Association
Standard for Welded Steel Tanks for Water Storage;
American Water Works Association
Standard for Painting Steel Water-Storage Tanks;
American Water Works Association
Steel Pipe Design and Installation; American Water Works
Association
2-5
2.1.1.4 Roads and Bridges
AASHTO HB-12
AASHTO ISB
AASHTO WSB-3
AASHTO LTS-1
AASHTO CD-2
AASHTO HDG
AASHTO HDG-7
AASHTO GSH-4
2-379-JJ
Standard Specifications for Highway Bridges, Twelfth
Edition; American Associations of State Highway and
Transportation Officials
Interim Specifications -Bridges; American Association
of State Highway and Transportation Officials
Standard Specifications for Welding Structural Steel
Highway Bridges; American Association of State Highway
and Transportation Officials
Standard Specifications for Structural Supports for
Highway Signs; Luminaires, and Traffic Signals; American
Association of State Highway and Transportation
Officials
A Policy on Geometric Design of Rural Highways; American
Association of State Highway and Transportation
Officials
Highway Drainage Guidelines; American Association of
State Highway and Transportation Officials
Hydraulic Analyses for the
Bridges; American Association
Transportation Officials
Location and
of State
Design
Highway
of
and
Guide Specifications for Highway Construction; American
Association of State Highway and Transportation
Officials
2-6
AASHTO HLED-1 A Guide for Highway Landscape and Environmental Design;
American Association of State Highway and Transportation
Officials
AASHTO GWP-1 A Design Guide for Wildlife Protection and Conservation
for Transportation Facilities
2.1.1.6 Design Guides
SEAOC-80 Recommended Lateral Force Requirements and Commentary,
Structural Engineers Association of California, 1980
Edition
ATC 3-06
NFPA
DOT/PF
SJI
Tentative Provisions for the Development of Seismic
Regulations for Buildings; Applied Technology Council
National Fire Protection Association
Alaska Department of Transportation and Public
Facilities, Design Standards for Buildings
Standard Specifications and Load Tables Steel Joist
Institute (SJI)
2.2 DESIGN LOADS
The following design loads are being considered with the loading
combinations described in Section 2.3.2 for the Design of Structures.
2.2.1 Dead Loads
Mass Concrete 145 lbs/ft 3
Reinforced Concrete 150 lbs/ft 3
Steel 490 lbs/ft 3
Water 62.4 lbs/ft3
Ice 56 lbs/ft 3
Salt Water 64 lbs/ft 3
2-379-JJ 2-7
Silt -Vertical 120 lbs/ft 3
-Horizontal 85 lbs/ft 3
Backfill
-Dry 120 lbs/ft 3
-Saturated 135 lbs/ft 3
-Submerged 75 lbs/ft 3
Sound Rock 170 lbs/ft 3
2.2.2 Backfill Loads
The lateral earth pressure against vertical faces of structures with
cohesionless horizontal backfill is computed using the equivalent fluid
pressures calculated from:
p kwH
Where:
p = unit pressure
k = pressure coefficient
w unit weight of fill
H = height of fill
For structures free to deflect or rotate about the base the pressure
coefficient is computed from Rankine's theory, using the following
equation:
2 tan ( 45-0/2)
Where 0 =angle of internal friction (degrees).
For structures restrained from bending or rotation, the at-rest
pressure coefficient is used:
2-379-JJ
k = 1 -sin 0
0
2-8
Coulomb's theory is used for computing lateral earth pressures on wall
surfaces with slopes flatter than lOV: 1H or with sloping backfill
steeper than 1V:4H.
Where vehicular traffic can run adjacent to the structure, a surcharge
loading of 300 lbs/ft2 is applied.
2.2.3 Snow and Ice Loads
Roofs. decks, and structural features which will carry snow or ice
loads are designed in accordance with the technical document ETL
111Q-3-317, U.S. Dept. of Army with additional provisions where more
severe icing is considered likely.
2.2.4 Floor Loads
1. Powerhouse
Generator Floor
Turbine Floor
Spherical Valve Pit Floors
Stairs
Control Room Floor
Tailrace Deck
Service Bay Floor
Equipment Floor
Office and Lunch Room
2. Intake Gate Shaft
Equipment Floors
3. Diversion Gate House
Equipment Floor
2-379-JJ 2-9
300 lbs/ft2
300 lbs/ft 2
300 lbs/ft2
100 lbs/ft 2
150 lbs/ft 2
300 lbs/ft 2
800 lbs/ft 2
300 lbs/ft 2
100 lbs/ft2
300 lbs/ft 2
300 lbs/ft 2
4. Warehouse and Machine Shop
Main Floor
2.2.5 Crane Runway Loads
2 250 lbs/ft
The powerhouse crane runways and supporting structure are constructed
of steel with the structural design based on: the runway-life span (50
years); crane type, classification and arrangement; number, width and
diameter of wheels; rate at which hoists operate; and the number of
anticipated load cycles. The structural design is based on the
distance between wheels, number of wheels and maximum wheel loadings.
Powerhouse cranes have relatively low hoisting speeds and DC controls,
which provide for more precise handling. Values to be used for impact
and horizontal forces for the powerhouse crane shall be as follows:
Rated Load,
Tons
150
*Impact
%
10
**Lateral
Force, %
10
*Based on maximum wheel loads.
***Longitudinal
Force, %
10
**Based on rated loads plus trolley weight applied at
top of crane rail, half on each side.
***Based on maximum wheel loads applied at top of rail.
Impact and horizontal forces shall be included in the design of columns
but not footings.
simultaneously.
Side thrust and impact shall not be considered
Neither earthquake nor wind loads shall be considered acting
simultaneously with crane live loads in designing columns and
foundations. Full wind or seismic shall be considered acting with
crane dead load.
2-379-JJ 2-10
Supports for hoist monorails shall be designed to include the trolley,
hoist, and monorail loads, and any pipe loads. Impact for
motor-operated hoists shall be 25 percent of the lifting capacity added
to the hoist and trolley load.
Deflections
Cab or Pendant Operated
(Live load without impact)
Fatigue
L/1200 Vertical Deflection
L/400 Lateral Deflection
Fatigue is evaluated in accordance with Appendix B of the AISC
Specification for the Design, Fabrication & Erection of Structural
Steel for Buildings.
The crane runway is comprised of suitably supported crane rail
connected by joint or splice bars. The rail is supported directly on
the top of the flange of a steel girder. The crane rail is fastened by
means of rail clips which allow the rail to expand and contract
longitudinally but hold the rail vertically and laterally.
Bumper stops are provided at each end of the crane runway. Bumper
stops are designed to withstand a 40 percent crane speed carrying the
rated load. A spring or hydraulic bumper impacting a steel stop will
be used.
2.2.6 Hydraulic Loads
All structures are designed for full lateral water pressures, including
hydrodynamic and uplift forces, where applicable.
2.2. 7 Uplift
Uplift (or internal hydrostatic pressure) is assumed to act over 100
percent of the affected area of the structure.
2-379-JJ 2-11
Uplift pressure is equivalent to the full water pressure acting on a
foundation or structure where no head differential exists across the
structure. The foundations and structures are analyzed for flotation,
if applicable.
Foundation drain holes are provided for the spillway downstream of the
foundation grout curtain. The drain holes are drilled into the
foundation rock and extend through the concrete structure to the top of
the ogee to permit inspection and maintenance of each drain. The drain
top detail includes a removable cap. The drains are connected by
headers and discharge downstream of the structure. The header outlets
are accessible for clean-out if required. The uplift pressures under
the spillway are considered across the complete rock/concrete interface
with full headwater pressure at the upstream face to grout curtain then
varying linearly to 1/2 headwater pressure at the line of drains to the
tailwater elevation. The projected pressure at the drains is based
upon the effectiveness of the drainage system expressed as drain
efficiency. For example, a drainage efficiency of 100 percent
corresponds to a reduction of the projected piezometric pressure
elevation to tailwater elevation at the line of drains. The expression
for the drainage efficiency is:
where
DW
HW =
DL =
TW
DE (HW-DL) X 100
(HW-TW)
drainage efficiency,
headwater elevation,
projected piezometric
of drains, feet
tailwater elevation,
percent
feet
elevation at the center line
feet
The drainage efficiency for the drains at the spillway is assumed to be
50 percent with the drains operative and with proper maintenance of
drains.
2-379-JJ 2-12
The spillway aprons and walls on grade are designed for uplift
conditions resulting from sudden changes in water level, as applicable
as well as groundwater and seepage pressures. Suitable drainage is
provided to equalize the water pressure on each side of the apron or
wall to minimize the differential pressures which may be expected.
2.2.8 Seismic Loads
The Bradley Lake Project is located in a seismically active region.
All major Project structures except the barge dock and airstrip are
founded on or excavated in rock. Design acceleration values given in
this design data are horizontal accelerations in rock and are amplified
or attenuated up through soil as applicable in design ••
1. Main Dam
The main dam is designed for an earthquake with the response
spectrum shown in Appendix A on Figure 6. 2-5, Mean Horizontal
Response Spectrum, and a normalized peak acceleration of 0. 75 g
which represents the maximum credible earthquake. The dam is
designed for this severe acceleration to maintain water retaining
integrity. The field studies conducted to date have not revealed
any geological structure in the dam site area which could be
considered active.
2. Intake Structure and Gate Shaft for Power Tunnel
The power intake structure and gate shaft are designed for an
earthquake with the response spectrum shown in Appendix A on
Figure 6.2-5, Mean Horizontal Response Spectrum, and a normalized
peak acceleration of 0.75 g with a 50 percent increase in
allowable stresses. The intake gates are designed to operate
after a major seismic event to close the water passageway of the
power conduit. To assure the gates remain operable, separate
air-oil accumulators are provided for each gate, with a tank size
to permit independent closure of each gate before recharging is
2-379-JJ 2-13
required by the hydraulic power pack. This approach assumes that
following power outage the hydraulic power pack become inoperable,
but permits gate operation.
3. Permanent Outlet Facilities in Diversion Tunnel
The permanent outlet facilities are designed for an earthquake
with the response spectrum shown in Appendix A on Figure 6.2-5,
Mean Horizontal Response Spectrum, and a normalized peak
acceleration of 0. 75 g with a 50 percent increase in allowable
stresses. The outlet gates are designed to operate after a major
seismic event specifically to open the main (downstream) gate to
effect reservoir drawdown. The guard gate (upstream) is normally
open. To assure the gate remains operable, air-oil accumulators
are provided with a tank size to permit one open-close cycle of
one gate before recharging is required by the hydraulic power
pack. This approach assumes that following power outage the
hydraulic power pack become inoperable, but permits gate
operation.
4. Power Tunnel
Fully embedded installations will react in concert with the
surrounding rock mass, unless actual rupture and displacement of
the rock mass occurs. The power tunnel crosses the Bradley River
and Bull Moose Faults, each of which are assumed to be capable of
independent earthquake generation, implying surface and subsurface
rupture potential. In addition, these faults are capable of
rupture in response to events on adjacent larger faults.
It is considered impossible for the design to withstand or
accommodate rock mass rupture. Other than safety-related issues,
no consideration other than those consistent with normal tunnel
design is applied. In the event rupture should occur, the power
tunnel will be dewatered and repairs made.
2-379-JJ 2-14
5. Steel Liner and Penstock
The steel liner and penstock are encased in concrete in excavated
rock tunnels as shown on Plate 9.
Once installation is complete, the fully embedded installation
will react in concert with the surrounding rock mass. For
conditions during installation and testing, an effective seismic
acceleration of 0.35 g will be considered with a one third
increase in allowable stresses.
The closure of two penstock inlets into the powerhouse is by the
spherical valves located within the powerhouse. The future
powerhouse penstock is closed off by a high pressure sperical
head.
6. Powerhouse
The powerhouse is designed for an effective seismic acceleration
of 0. 35 g with material stresses not exceeding normal design
working stresses, and for an earthquake with the response spectrum
shown in Appendix A on Figure F6. 2-5, Mean Horizontal Response
Spectrum, and a normalized peak acceleration of 0.75 g with
material stresses not exceeding 150 percent of the normal design
working stresses. The powerhouse substructure is constructed of
concrete securely founded in rock. The powerhouse superstructure
is an insulated steel framed metal clad enclosure of conventional
design.
7. Middle Fork Diversion
The Middle Fork Diversion Dam is designed for an earthquake with
the response spectrum shown in Appendix A on Figure F6.2-5, Mean
Horizontal Response Spectrum, and a normalized peak acceleration
of 0.35 g. The proposed dam is designed for this severe
acceleration to retain the reservoir impoundment.
2-379-JJ 2-15
8. Other Project Structures and Facilities (including Nuka Diversion)
The other project structures are designed for an effective seismic
acceleration of 0.35 g consistent with U.B.C. Zone 4.
Some facilities including the barge dock, access roads, and the
airstrip are founded on soil formations in the tidal flats. Local
soil failures are anticipated for these facilities during seismic
events and will be repaired as needed.
2.2.9 Temperature and Thermal Loads
Expansion and contraction resulting from temperature changes, moisture
changes, creep in component materials, and movement resulting from
differential settlement will be combined with other forces and loadings
for maximum effects. The minimum design temperature is -30°F and the
maximum design temperature is +85°F.
2.2.10 Horizontal Ice Loads
The design ice thickness for Bradley Lake is 28 inches. Using charts
developed by E. Rose in the paper "Thrust Exerted by Expanding Ice
Sheet" Trans. ASCE Vol. 1 and 2, 1947, page 871 and also included in
the USBR book "Design of Small Dams" figure 220, the 28 inch thickness
of ice results in a horizontal ice load of 12 kips per lineal foot,
assuming no lateral restraint to ice and a temperature rise of
15°F/hour.
Excessive ice buildup on trashracks, gates, gate guides, and critical
areas of structures will be prevented by providing adequate submergence
or heating of such equipment.
2.2.11 Wind and Wind Related Loads
Wind data at the site has been gathered since August 1979. The
analysis of the limited data indicates that highest winds occur from
October through April with several events exceeding 70 mph during this
2-379-JJ 2-16
period (maximum 106 mph recorded). The 100 year return period speed
has been estimated at 115 mph in the area with the predominate
direction of the winds toward the northwest.
Wind loads developed for the Bradley Lake project are based on the 1985
Uniform Building Code formula for wind pressure:
where:
p C C q I e q s (UBC 11-1)
p = design wind pressure
C = combined height, exposure and gust factor coefficient as e
given in UBC Table No. 23-G
C = pressure coefficient for the structure or portion of q
structure under consideration as given in UBC Table
No. 23-H
qs = wind stagnation pressure at the standard height of 30 ft
as set forth in UBC Table 23-F
I = importance factor as set forth in UBC Section 2311(h)
Wind Load Application
Wind loads are applied orthogonally to buildings and structures in only
one direction at a time. For tanks or structures supported on four
legs in an elevated position wind load is applied diagonally. Wind
loads are not combined with earthquake loadings; however. they are
applied in combination with snow loads.
Wind Load Importance Factor
Design
Wind
Importance Speed
Area Exposure Factor (mph)
Main Dam Diversion Outlet B 1.0 120
Structures
Main Dam Diversion Gate House c 1.15 120
Main Dam Structures c 1.15 120
2-379-JJ 2-17
Wind Load Importance Factor (Continued)
Design
Wind
Importance Speed
Area Exposure Factor (mph)
Powerhouse and Attached Average 1.15 100
Facilities of B+C
Substation Average 1.15 100
of B+C
Nuka Diversion Structures B 1.0 120
Middle Fork Diversion B 1.0 120
Structures
Miscellaneous Structures B 1.0 100
Exposed Coastal Facilities c 1.15 100
2.3 STABILITY CRITERIA
The stability analysis of the dam and spillway structures that will be
constructed during the Civil Construction Contract are being conducted
and these will be included as part of the Civil Construction Contract
Final Supporting Design Report. The following describes the criteria
being considered for the stability analysis.
2.3.1 Main Dam Stability
The main dam is a compacted rockfill founded on competent bedrock with
an upstream concrete face slab membrane. A general plan and sections
of the dam are shown in Appendix A Exhibit F Plates 2 and 3. The
following criteria is being considered in the stability analysis.
1. Reservoir Elevations
0
0
0
2-379-JJ
Probable Maximum Flood
Normal Maximum Operating
Minimum Operating
2-18
1190.6
1180
1080
2. Tailwater Elevations
0
0
0
Probable Maximum Flood
Normal Maximum Operating
Minimum Operating
3. Uplift and Seepage Forces
1081
1067
1061
o At Base -full reservoir pressure at upstream face
o Internal full reservoir pressure at upstream concrete
membrane, .dropping to tailwater hydrostatic pressure within
embankment
o Upstream concrete membrane is impervious compared to
rockfill. No excess pore pressures develop for construction
or drawdown loading conditions.
4. Embankment Geometry
o Crest Elevation -1190
o Foundation Elevation -1065 (Minimum)
o Alignment of Axis -Essentially straight but with a slight
upstream camber
o Crest Width -16 Feet
o Camber -Camber the dam crest to prevent loss of freeboard
under static settlement and anticipated design basic seismic
conditions.
5. Slope Protection
o Upstream Slope -Reinforced concrete face slab membrane
o Downstream Slope -Rockfill with heavy riprap below maximum
flood level
2-3 79-JJ 2-19
6. Material Properties
o Rockfill
Dry/Moist Unit Weight
Saturated Unit Weight
Shear Strength
o Internal Friction
o Cohesion
Shear Wave Velocity
Damping
120 lbs/ft 3
135 lbs/ft 3
45°
0
1000 ft/sec
5% minimum
Permeability -Previous relative to upstream concrete
membrane
o Upstream Concrete Membrane
Strength -To be determined
Permability -To be determined based on joint seepage and
seismic cracked section
o Water
Unit Weight 62.4 lbs/ft 3
7. Silt
o No silt loads
8. Ice, Wind, Hydrodynamic Load~
These loads are listed in Section 2.1.2.10 for ice loads, Section
2.1.2.11 for wind loads, and Section 2.1.2.6.7 for hydrodynamic
loads.
9. Earthquake
o Horizontal earthquake with the response spectrum shown on
Figure F6.2-5, Mean Horizontal Response Spectrum, and a
normalized peak 0.75 g acceleration.
2-379-JJ 2-20
o Vertical earthquake acceleration is applied separately as two
thirds of horizontal acceleration.
10. Method of Analysis
o Static analysis -two dimensional simplified Bishop Method of
Slices using circular sliding surfaces and infinite slope
analyses, and sliding wedge failure analysis.
0 Dynamic Analysis two dimensional simplified permanent
displacement method by Newmark, utilizing Sarma seismic
amplification from base to top of dam.
11. Loading Combinations
Case I -Normal Conditions
o Normal Maximum Reservoir El. 1180
o Uplift and Seepage Forces
o Dead Loads
o Ice at El. 1179
Case II -Unusual Condition -Probable Maximum Flood (PMF)
o Maximum Reservoir El. 1190.61
o Uplift and Seepage Forces
o Dead Loads
o Earthquake not considered
Case III -Extreme Condition -Earthquake
o Normal Maximum Reservoir El. 1180
o Uplift and Seepage Forces
o Dead Loads
o Ice at El. 1179
o Maximum Credible Earthquake
2-379-JJ 2-21
Case IV -Construction Condition
o Reservoir Water Surface at El. 1065
o Dead Load
o Earthquake
Case V -Reservoir Drawdown
o Drawdown from spillway crest to minimum reservoir elevation
1080
o Uplift and Seepage Forces
o Ice Load
o Dead Load
o Design Basis Earthquake
12. Factors of Safety
0 Static Loading Condition
Construction Condition
Normal Operating Maximum Reservoir
Reservoir Drawdown
Maximum Reservoir Level
o Dynamic Loading Condition
Required Minimum Factor
of Safety
1.3
1.5
1.2
1.4
The loss of freeboard and damage to the dam during an
earthquake event described in the subsection 9. Earthquake
should not cause catastrophic failure of the dam.
13. Sections to be Analyzed
o The embankment is analyzed for a unit width slice through a
section at the maximum height.
2-379-JJ 2-22
o Abutm~nt geometry is considered for strain compatibility
o Crest conditions are considered for local topographic
amplification effects
2.3.2 Spillway Stability
The spillway is a concrete ogee section founded on competent bedrock in
a saddle on the right side of the main dam. The spillway is shown in
Appendix A Exhibit F on Plate 4. The following criteria are being
considered for the stability analysis of the spillway.
1. Reservoir Elevation
0
0
0
Probable Maximum Flood
Normal Maximum Operating
Normal Minimum Operating
1190.6
1180
1080
2. Tailrace Elevation
o Tailwater elevation will have no direct effects on spillway
stability as the toe is well above tailwater pool level.
3. Uplift
0
0
2-379-JJ
At Base
Internal
Reservoir pressure at upstream face to grout
curtain then varying to 1/2 upstream face
pressure at drains and to 1/2 flow depth
pressure at downstream face of apron
Full reservoir pressure at upstream face
decreasing linearly to tailwater pressure at
downstream face of spillway arpon
Uplift assumed to act over 100% of base area
2-23
4.
5.
6.
Dead
0
0
Silt
0
Ice
In all cases, uplift on any portion of the base or section
not in compression is assumed to be 100% of the assumed
upstream head except when the non-compressive foundation
pressure is the result of earthquake forces. During the
earthquake loading condition, when the resultant is located
outside the kern of the section, the uplift is not revised
from that used in the normal operating condition.
Weights
Concrete 145.0 lbs/ft 3
Water 62.4 lbs/ft 3
No silt loads
o 12 kips/ft applied at elevation 1179 (based on 28 inch ice
thickness and developed as described in Section 2.1.2.10)
7. Earthquake
The horizontal earthquake loads are based on the response spectrum
shown on Figure 6.2-5, Mean Horizontal Response Spectrum and a
normalized peak acceleration of 0.75 g.
The horizontal earthquake water loads are based on the formula as
developed in USBR "Design of Small Dams" Chapter VIII Section 170
which is
2-379-JJ 2-24
where
P = C E w h e
P = increase in water pressure in psf at any elevation due e
to horizontal earthquake
C dimensionless coefficient from Figure 222 USBR "Design
of Small Dams"
E = earthquake intensity
w =unit weight of water in pounds/cu. ft.
h total depth of reservoir at section studied in feet
The vertical earthquake loads are applied separately as 2/3 the
horizontal earthquake load.
8. Temperature
Minimum temperature
Maximum temperature
9. Wind
The wind loads are developed from the formula listed in Section
2.1.2.11.
10. Loading Combinations
Case I -Normal Conditions
o Normal Maximum Reservoir El. 1180
o Uplift and Seepage Forces
o Dead Loads
o Ice at El. 1179
2-379-JJ 2-25
Case II -Unusual Condition -Probable Maximum Flood (PMF)
o Maximum Reservoir El. 1190.6
o Uplift and Seepage Forces
o Dead Loads
o Earthquake not considered
Case III -Extreme Condition -Earthquake
o Normal Maximum Reservoir El. 1180
o Uplift and Seepage Forces
o Dead Loads
o Ice at El. 1179
o Maximum Credible Earthquake
Case IV -Construction Condition
o Reservoir Water Surface at El 1065
o Dead Load
o Earthquake
Case V -Reservoir Drawdown
o Drawdown from spillway crest to minimum reservoir elevation
1080
o Uplift and Seepage Forces
o Ice Load
o Dead Load
o Design Basis Earthquake
2-3 79-JJ 2-26
11. Factors of Safety
o Allowable Stresses -Maximum
Concrete 4000 psi
Compression, psi
Tension, psi
Factor of Safety
Rock
Bearing Capacity,
psf
o Sliding
Case I Case II
Normal Unusual
1300 2000
0 0
3 2
12,000 15,000
Case III
Extreme
3500
0
1.15
20,000
Case IV
Construction
3000
30
1.33
17,000
Based on shear friction factor of safety computed by
Q CA + N tan ¢ =
H
where
Q = Shear Friction Factor of Safety
c Unit Cohesion
A = Area Base Section in Compression
N = Summation Normal Loads Including Uplift
0 = Internal Friction Angle
35° Concrete at Lift Lines
35° Concrete on Sound Rock
H = Summation Horizontal Shearing Loads
2-379-JJ 2-27
. .
Case I Case II Case III Case IV
Normal Unusual Extreme Construction
Based on Adhesion
and Friction 4 2 1.5 1. 25
Based on Adhesion 2 1.5 1.1 1.1
Only
2.3.3 Middle Fork Diversion Dam Stability
The dam is a compacted rockfill with a central sheetpile cutoff wall
and is founded on competent bedrock. Details of the dam are shown in
Appendix A Exhibit F on Plate 12. The following criteria are being
considered for the stability analyses.
1. Reservoir Elevations
2.
0 Design Flood
0 Normal Maximum Operating
0 Minimum Operating
0 Empty
Tailwater Elevations
0
0
0
Flood
Normal Maximum Operating •.
Minimum Operating
2210
2204
2192
2192
2192
2192
2192
3. Uplift and Seepage Forces
o At Base -Full reservoir pressure upstream of sheetpile wall
varying to the base of the embankment. 2 feet downstream of
sheetpile wall.
o Internal -Full reservoir pressure upstream of sheetpile wall
varying to the base of the embankment, 2 feet downstream of
sheetpile wall.
2-379-JJ 2-28
0 The sheetpile cutoff wall will be impervious compared to
rockfill (joints in the sheetpile will be sealed). No excess
pore pressures will develop in rockfill during construction
or drawdown.
4. Embankment Geometry
o Crest Elevation 2212
o Foundation Elevation 2192 (Minimum)
o Alignment of Axis -Straight
o Crest Width -20 Feet
o Camber -Camber the dam crest to prevent loss of freeboard
under static settlement conditions.
5. Slope Protection
o Upstream Slope -Rockfill
o Downstream Slope -Rockfill
6. Material Properties
0 Rockfill
Dry/Moist Unit Weight 120 lbs/ft 3
Saturated Unit Weight 135 lbs/ft3
Shear Strength
0 Internal Friction 45°
0 Cohesion 0
Shear Wave Velocity 650 ft/sec
Damping 5% minimum
Permeability -Pervious relative to central sheetpile wall
o Sheetpile wall assumed to have the same strength as the
rockfill and to be impervious relative to the rockfill
o Water
Unit Weight 62.4 lbs/ft 3
2-379-JJ 2-29
7. Silt
o No silt loads.
8. Ice, Wind, Hydrodynamic Loads
o The ice loads are as shown in Section 2. 1. 2. 10. The wind
loads are as shown in Section 2 .1. 2 .11. The hydrodynamic
loads are as shown in Sections 2.1.2.6 and 2.1.2.7.
9. Earthquake
o Horizontal earthquake with the response spectrum shown on
Figure F6.2-5, Mean Horizontal Response Spectrum, and a
normalized peak 0.35 g acceleration.
o Vertical earthquake acceleration applied separately as two
thirds of horizontal acceleration.
10. Method of Analysis
o Static analysis -two dimensional simplified Bishop Method of
Slices using circular sliding surfaces and infinite slope
analyses.
0 Dynamic Analysis two dimensional simplified permanent
displacement method by Newmark.
11. Loading Combinations
Case I -Normal Conditions
o Normal Maximum Reservoir El. 2204
o Uplift and Seepage Forces
o Dead Loads
o Ice Load
2-379-JJ 2-30
Case II -Unusual Condition -Probable Maximum Flood (PMF)
o Maximum Reservoir El. 2210
o Uplift and Seepage Forces
o Dead Loads
o Earthquake not considered
Case III -Extreme Condition -Earthquake
o Normal Maximum Reservoir El. 2204
o Uplift and Seepage Forces
o Dead Loads
o Ice Load
o Maximum Credible Earthquake
Case IV -Construction Condition
o Reservoir Empty
o Dead Load
o Earthquake
Case V -Reservoir Drawdown
o Drawdown from spillway crest to minimum reservoir elevation
2192
o Uplift and Seepage Forces
o Ice Load
o Dead Load
o Design Basis Earthquake
2-379-JJ 2-31
12. Factors of Safety
0 Static Loading Condition
Construction Condition
Normal Maximum Reservoir Operating
Reservoir Drawdown
Maximum Reservoir Level
o Dynamic Loading Condition
Required Minimum Factor
of Safety
1.3
1.5
1.2
1.4
The loss of freeboard and damage to the dam during an
earthquake event described in the subsection 9. Earthquake.
should not cause catastrophic failure of the dam.
13. Sections to be Analyzed
o The embankment is analyzed for a unit width slice through the
section at the maximum height.
2.1.3.4 Powerhouse Stability
The powerhouse has a concrete substructure and a steel superstructure
as shown in Appendix A Exhibit F on Plate 9. It is basically
rectangular in plan. approximately 163.5 feet long and 82.5 feet wide.
The base of the turbine discharge chamber slab is at elevation -9. The
concrete substructure will be founded in rock. The initial powerhouse
bench excavation that will be part of the Site Preparation Contract is
shown in Appendix A Exhibit F on Plates 7 and 8.
The powerhouse is situated on an excavated bench with free drainage to
tailwater. Due to the potential for the water passageways to be
dewatered, the powerhouse is being analyzed for flotation using the
following criteria.
2-379-JJ 2-32
1. Tailwater Elevation
o The highest tide elevation is 11.4 feet.
o Maximum storm surge elevation is 13.3 feet.
2. Uplift
o Uplift assumed to act over 100 percent of the base area.
o The uplift is considered equivalent to the full water
pressure acting on the foundation or structure.
o Post tensioned anchor forces may be used to increase factor
of safety against flotation sliding, uplift, or overturning.
o Certain floor slab areas are deliberately drained, so 50%
drain efficiency is assumed in this case using maintained
pipe drains
3. Dead Weights
4.
0
0
Reinforced Concrete
Salt Water
150 lb/ft 3
64.0 lb/ft3
o The weight of the steel superstructure and the equipment is
not considered to assist against flotation.
o No silt loads.
5. Ice
o Since ice weight can only add to the dead weight of the
structure, it is not considered to assist against flotation.
Rim ice on the face of the structure is not expected to form
and will therefore not affect uplift.
2-379-JJ 2-33
6. Loading Combinations
Case I -Dewatered Condition
o Tailwater Elevation 11.4 feet
o Uplift
o Dead load due to concrete only
Case II -Maximum Storm Surge
o Tailwater Elevation 13.3 feet
o Uplift
o Dead load due to concrete only
7. Factors of Safety
Factor of Safety Against Flotation = 1.5, where
Factor of Safety Against Flotation Dead Weight (including post
Buoyant Force tension anchor
forces)
Factor of Safety = 1.05 not including post tensioning anchor force
8. Sliding
The powerhouse substructure below Elevation 23 is integrally keyed
into the surrounding rock.
9. Earthquake
The powerhouse is designed for an effective seismic acceleration
of 0.35 g with material stresses not exceeding normal design
working stresses, and for an earthquake with a response spectrum
shown on Figure F6.2-5, Mean Horizontal Response Spectrum and a
normalized peak acceleration of 0.75 g with material stresses not
exceeding 150 percent of the normal design working stresses.
2-379-JJ 2-34
10. Section Analyzed
o The entire two unit substructure is analyzed for flotation,
and for overturning action due to the non-uniform
distribution of weight and uplift.
2.1.4 Material Properties
2.1.4.1 Concrete Materials
As part of the Site Preparation Contract a concrete testing laboratory
will develop concrete mixes for two design strength concrete mixes and
one starter grout mix.
These mixes will have the following design strengths at 28 days:
Mix 1 3000 psi
Mix 2 4000 psi
Mix 3 Starter grout for horizontal construction joints
2.1.4.2 Reinforcing Steel
Reinforcing steel will be required in bar sizes No. 4 through No. 18
bars. All bars will conform to the Specifications for Deformed Billet
Steel Bars for Concrete Reinforcement, ASTM A615, Grade 60 including
supplement S1. The maximum bar length will be 40 feet.
Welded wire fabric will conform to ASTM A185.
2.1.4.3 Water Stops
Water stops are either natural rubber, synthetic rubber neoprene or
polyvinyl chloride and satisfy CRD C513 for natural or synthetic and
CRD 572 for polyvinyl chloride water stops. Water stops are provided
in:
o all expansion and contraction joints
o all vertical construction joints communicating with dry
interior spaces;
2-379-JJ 2-35
o all horizontal construction joints communicating with dry
interior spaces where the concrete thickness is less than 10
feet.
2.1.4.4 Structural Steel
Structural steel will be ASTM A36 (Minimum yield stress
ASTM A572 (Minimum yield stress= 50 ksi).
2.1.4.5 Structural Connections
1. Bolted Connections
36 ksi) or
Bolts and hardware will conform to ASTM A325 Type 1 Class E for
high strength connections or ASTM A307 for normal strength
connections. High strength bolted connections will be friction
type joints due to reversible wind and seismic loading.
2. Welded Connections
All structural welded connections will be in accordance with AWS
D1.1 using prequalified welded joints.
follow:
Steel
ASTM A36
ASTM 572
Electrodes
E70XX
E80XX
Electrode requirements
Pressure vessel welding requirements will be in accordance with
ASTM VIII, Pressure Vessels.
2.1.4.6 Tunnel Steel Liner and Penstock
The tunnel steel liner and penstock will be constructed from high
strength steel plates conforming to ASTM A710 with minimum yield
strength for up to 1-1/4 inch plates of 90,000 psi, for over 1-1/4 to 2
inch plates of 75,000 psi, for over 2 inch to 4 inch plates of 65,000
psi.
2-379-JJ 2-36
2.2 GENERAL TECHNICAL DATA
2.2.1 Reservoir
Elevation of Existing Lake Surface, feet
Elevation of Maximum Operating Pool, feet
Elevation at Minimum Operating Pool, feet
Elevation at Emergency Drawdown, feet
Elevation at Probable Maximum Flood, feet
Area of Reservoir at Full-Pool, acres
Area of Reservoir at Minimum Pool, acres
Normal Active Storage Capacity, acre-feet
Additional Storage for Emergency Generation,
acre-feet
2.2.2 Bradley Lake Dam
1,080
1,180
1,080
1,060
1,190.6
3,820
1,598
284' 150
31,200
Type
Length, feet
Height of Maximum Section, feet
Top of Dam Elevation, feet
Concrete Faced Rockfill
610
125
1,190
2.2.3 Bradley Lake Spillway
Spillway Type
Spillway Crest Elevation, feet
Gross Spillway Length, feet
Spillway Crest Length, feet
2.2.4 Power Tunnel
Length (concrete and steel lined), feet
Inside Diameter (concrete lined), feet
Intake Invert Elevation, feet
2-379-JJ 2-37
Ungated Ogee
1,180
260
175
18,820
11.0
1,030
2.2.5 Steel Liner and Penstock
2.2.5.1 Liner
Type
Nominal Diameter, feet
Length, feet
Material
Minimum Yield Strength, psi
To 1-1/4 inch thick liner
Over 1-1/4 inch to 2 inch thick liner
Over 2 inch to 4 inch thick liner
2.2.5.2 Penstock
Length, feet
Outside Diameter at Portal, feet
Material
Embedded
11
2,600
ASTM A710
90,000
75,000
65,000
230
11
ASTM A710
Minimum Yield Strength, psi (same as liner yield strength)
Diameters of Manifold, feet 11 and 6.5, 9 and 6.5
Diameter of Inlet to Powerhouse, feet 6.5
2.2.6 Powerhouse
Total Plant Nameplate Rating, KVA
Number of Units
Type of Turbine
Turbine Rating at 1130 Feet Rated Net Head, hp
Rating of Generating Unit, KVA (nameplate)
Maximum Operating Pool Elevation, feet
Minimum Operating Pool Elevation, feet
Maximum Tailwater Elevation, feet
Minimum Tailwater Elevation, feet
Centerline Turbine Runner Elevation, feet
Bottom of Turbine Chamber, feet
Unit Spacing, feet
2-379-JJ 2-38
125,000
2
Pelton
82,000
62,500
1,180
1,080
11.4
6
15
6
60
2.2.7 Project Generation
Flow regime is Bradley River, Middle Fork Diversion, Nuka Diversion and
releases for fish habitat.
Yearly Firm Energy, GWh
Average Annual Energy, GWh
Secondary Energy, GWh
2.2.8 Substation and-Transformers
Generator Bus
Type
Rating
Enclosure
In powerhouse
Outside powerhouse
Main Transformers
Number
Rating
Substation
334.1
369.2
35. 1
Copper Conductor
Non-segregated Phase
15,000 volts; 3,000 amps
Continuous; 80,000 amps
Momentary
Ventilated
Enclosed and weatherproof
2 plus 1 spare
OA/FA/FA
33.8/45/56.3 MVA
Three phase, 60 Hz
Type
Configuragation
Rating
SF 6 Compact Gas Insulated Substation
4 breaker ring bus
121 KV, 1200 amp
2-379-JJ 2-39
2.2.9 Transmission Line
Number of lines
Type
Voltage, kilovolts
Conductor size, KCM, ACSR; uDrake 11
Overall length overhead section, miles
2. 2.10 _ Tail water Data for Powerhouse
Bear Cove Bear Cove
MLLW MSL
Tides Datum Datum
HT 25.00 15.39
MHHW 18.41 8.80
MHW 17.60 7.99
MSL 9.61 0.00
MLW 1.61 -8.00
MLLW 0.00 -9.61
LT -6.00 -15.61
2-379-JJ 2-40
2 parallel
H-Frame/Wood Pole
115
795
20
Bradley Lake
Project
Datum
11.37
4.78
3.987
-4.02
-12.02
-13.63
-19.63
SUITABILITY ASSESSMENT
3.0 SUITABILITY ASSESSMENT
This section addresses the geologic and soil conditions with respect to
Lheir suitability to accommodate the Bradley Lake Hydroelectric
Project. This assessment is divided into two parts. The first part
(Section 3.1) outlines the results of the geotechnical investigation
that was made for the Preliminary Supporting Design Report as contained
in the License Application for the Bradley Lake Hydroelectric Project.
The second part (Section 3.2) is the executive summary of the "Final
Site Conditions Report of Geotechnical Field Investigations for the
Bradley Lake Hydroelectric Project 1984 and 1985 Programs. The Final
Supporting Design Report for the Civil Construction Contract will
expand on these two sections.
A detailed discussion of the determination of general seismic effects
for the project area is included in Section 7.
3.1 SPECIFIC ASSESSMENTS FROM PRELIMINARY SUPPORTING
DESIGN REPORT
3. l. 1 Dam Site
Surficial geology at the site and logs of borings in the area are
included in the FERC License Application Volumes 5 through 10. Borings
made in the vicinity include: D-1, D-2; DH-4, -5, -6, -?EX, -16, -30,
-33, -34, -36, and SW 83-l. This boring information is shown in
Appendix D of Volume 9 of the License Appliction as listed in Section
4. Additional borings are included in the Final Site Conditions Report
of Geotechnical Field Investigations for the Bradley Lake Hydroelectric
Project 1984 and 1985 Program.
Investigations indicate that the
intake is in an area underlain
2-379-JJ
location of the proposed dam and
primarily by graywacke with some
3-l
argillite. The U.S. Army Corps of Engineers (COE) had previously
conducted investigations in the general area of the dam. Field checks
confirmed conditions delineated by the previous studies. Efforts for
the 1983 Feasibility Study were concentrated in the proposed intake
area, which is at a different location from that considered by the COE.
Damsite exploration by the COE included eight holes spaced along the
dam axis, which is very close to the selected dam axis. Drilling
indicated alternating sequence of argillite and graywacke along the
entire dam axis. Preliminary studies indicate generally good overall
rock quality. Two 45° angle holes were drilled, one on the left river
bank and one in the right abutment saddle, with lengths of 249.9 and
201.7 feet, respectively. Vertical holes at the left and right dam
abutments and saddle penetrated 248.3, 133.0, 246.9 and 75.1 feet of
rock, respectively. One short vertical hole (60 feet) was drilled in
the middle of the river.
The right (or east) abutment of the damsite is a continuous outcrop of
massive graywacke, exhibiting poorly developed bedding, in association
with thin lenses of cherty argillite. Bedding generally dips at high
angles to the west with a variable strike of about N 10° E to N 10° W.
Well developed joints are present; spacing varies from less than 1 feet
up to 10 feet. Th . . . "k N 60°-70° SE. e two maJor JO~nt patterns str~ e Dip
angles of these joint systems form an "X" and appear evenly divided
between 60°-70° NE and 60°-70° SW with a few steep dips of 80°-84° NE
and SW. Accessory joints are of minor importance. Overburden appears
shallow, with observed depths of 5 feet or less except in the river.
Joint rosette histograms were prepared for both right and left
abutments.
A number of minor shear zones or joint swarms were observed in the
general area. The largest of these is located on the north flank of
the left abutment knob, approximately 150 feet SW of the downstream end
of the small rock island. This fault strikes N 4° E and dips
vertically. The shear zone ranges from 1 to 15 inches wide and
2-379-JJ 3-2
contains a small amount of clayey, silt gouge. A crevice 15 inches to
3 feet wide is eroded 5 to 6 feet back from the face of the rock. A
possible continuance of the shear zone exists on the river side of the
left abutment knob. This zone is a linear feature about 3 feet wide at
the top, tapering to a soil-filled depression 2 feet wide. This
feature also approximately follows a minor joint trend and has a strike
of N 23° E and dips between 48°-59° SE. This fault is a minor
structural feature and is not considered to influence the proposed
location or design of the dam.
A borehole extensometer of the multiposition rod type, manufactured by
Slope Indicator Company, was installed in Borehole DH-7EX. This boring
is angled across the saddle where the spillway will be located. At one
time this was thought to possibly be the location of a significant
fault. Further studies indicate the existence of a major fault is
unlikely at this location, however small gouge zone were encountered.
The extensometer has not shown any significant movements since
installation (December 10, 1980).
Investigations in the right abutment saddle (spillway location)
indicate 17+ feet of talus and overburden overlying moderately jointed,
fractured graywacke. Minor weathering effects persist to the bottom of
COE hole DH-33; (75.1 feet). Polished, grooved, and striated bedrock
surfaces are present and are typical of areas recently vacated by ice.
The right abutment appears to be satisfactory for the planned dam and
spillway.
Overburden on the left abutment appears generally shallower than on the
right abutment and varies from 0.5 to 2.5 feet on the average in
boreholes. COE drill hole DH-35, drilled in 1981, indicates a depth of
9.4 feet of overburden at one point. Unconsolidated materials appear
in the saddles of both abutments. These materials include talus, sand,
gravel, and topsoil.
The left abutment is composed of a more argillaceous graywacke that
contains thin beds of argillite and argillite-graywacke interbeds.
2-379-JJ 3-3
Aligned, pillow-shaped pieces of graywacke, in a boudinage structure,
have been observed in exposed outcrops 600 feet to the south. COE
drilling logs from DH-5 and DH-16 show alternating argillite and
graywacke units and graywacke with various percentages of argillaceous
material. Observed jointing is similar to that of the right abutment,
with major joints cutting through bedding planes, striking N 55°-80° W
and dipping 80° SW to vertical. Minor localized joints strike N 75° E
with dips of from 78°-83° SE. The left abutment rock conditions are
also considered to be satisfactory.
The dam will be founded on bedrock composed chiefly of alternating
sequences of argillite and graywacke. The in situ rock visible at the
surface in the damsite area is all moderately hard to hard and is
considered quite adequate to support a rockfill dam. Surficial
weathering is generally confined to the upper few feet of rock;
however, staining on joints and fractures in the rock indicates
potential leakage channels from the reservoir and provision will be
made for seepage control. A grout curtain will be required beneath the
toe slab of the dam to control underseepage.
3.1.2 Reservoir Rim Stability
The entire reservoir rim except the delta area at the head of the lake
consists of bedrock which is either exposed or very thinly mantled by
collulvium and talus. The bedrock is insoluble and development of
instability due to solution channeling is not considered to be a
concern. There are no known points around the rim at which the bedrock
barrier is thin enough to be breached due to increased hydrostatic
pressure resulting from the increase in lake level. There are no known
joint or fault blocks of sufficient size to produce catastrophic waves
should sliding or toppling into the lake occur.
A talus slide on the north shore of the lake, about 700 feet to the
east of the dam is composed of small angular pieces mixed with coarse
and fine sands. This material is derived from fractured argillite and
graywacke and has formed a relatively stable slope reaching close to a
bluff edge. Benched cliffs across the lake, on the north shore, could
pose a threat because of their steepness; however, if failure occurred,
2-379-JJ 3-4
most of the material from the upper cliffs would fall on the rugged
terrace below. The lower cliffs would have minimal rock fall danger or
wave production potential because less than 200 feet of the cliff face
would be exposed when the reservoir is filled.
The reservoir rim is considered to be devoid of any potential for
catastrophic failures. either by breaching or production of waves of
overtopping proportions, and thus is suitable for the intended
reservoir.
3.1.3 Intake and Power Conduit
Borings SW 83-2 and SW 83-4 were made on the proposed tunnel alignment.
Borings DH-8, -9, -10EX, -14, -17EX, -34, -37, and -38 were drilled by
the COE along an earlier proposed alignment. Of those, DH-13 EX, -14,
-17 EX, -37, and -38 are within 500 feet or less of the current
alignment. Logs of these borings are included in Appendix H of the
License Application. Laboratory tests and petrographic analyses were
made of selected rock cores from various borings and from some surface
samples; results of these are also included in Appendix H of the
License Application. Interpretations based on data derived from the
borings, tests, and analyses are incorporated in the following
assessments. Subdivisions below are based on geographical terrain
rather than design elements. Additional investigations from 1984 -
1985 are included in the Final Site Conditions Report, of Geotechnical
Field Investigations for Bradley Lake Hydroelectric Project, Section
3.2.
3.1.3.1 Intake Area
Surface reconnaissance reveals that the rock is comprised of complexly
mixed graywacke and foliated argillite with less than 10 percent chert
nodules and layers. The contacts between the graywacke and argillite
roughly parallel the foliation in the a~gillite, which typically trends
N-S to N 20° E and dips steeply. Several small faults and joints sets
are present. These features have been described in some detail by
Woodward-Clyde (1979), and Dowl Engineers (1983), as part of their
2-379-JJ 3-5
investigations for the left abutment of the dam. No faults are known
to intersect the currently proposed location for the intake portal.
An east-northeast-trending topographic lineament, which passes near the
proposed location of the intake portal, was suspected to be the surface
expression of a rockmass discontinuity. This lineament is the gully
between Hill 1270.7 and Hill 1525.6. About 1,000 feet to the west of
Bradley River the lineament merges with an east-trending fault mapped
by Woodward-Clyde. Directly east across Bradley River, it trends into
the vicinity of two small covered areas which are probably the surface
expression of joints or small faults. The lineament also parallels an
east-trending fault located about 250 feet to the north on the east
side of the river, and a series of lineaments, of unknown origin, to
the southwest.
Boring SW83-2, oriented S6°W and angled at 45°, was made to define
subsurface conditions causing the prominent lineament. The boring was
oriented to cross the lineament described above and encountered 28.4
feet of colluvium and 126.9 feet of bedrock (20.1 feet and 89.7 feet
vertical depth). Bedrock is primarily graywacke with varying amounts
of associated argillite; the overall rock mass fabric appears to be
cataclastic in origin. Close to very close jointing was encountered in
portions of the boring; no indications of significant faulting were
found.
Since the feature sampled by Boring SW83-1 is the most prominent
lineament in the intake area, it is considered that the intake
facilities should not encounter any significant faults or shear zones.
Several minor shears have been previously mapped in the intake area
(Woodward-Clyde, 1979). These are well exposed and are not known to
exceed one to two feet in width. Several of these may be expected to
cross the intake channel but are not considered significant to
construction or operation of the facility. Geologic conditions are
considered to be satisfactory for construction of the proposed intake
facilities.
2-379-JJ 3-6
3.1.3.2 Tunnel -Bradley Lake to Bradley River Fault Zone
This easternmost section of the tunnel alignment is underlain by
interbedded graywacke and argillite. Because of their complex mixing,
these rock types have been mapped as a single unit comprised of
approximately 50 to 65 percent massive graywacke and 35 to 50 percent
argillite. The argillite is commonly foliated and occurs as interbeds
and pockets that range from less than a foot to as much as 100 feet
thick.
Jointing is more apparent along this section of the tunnel alignment
than further to the northwest. Several lineaments also cross this
section of the tunnel alignment at various orientations. It is
suspected that some of these features may be faults, but there is
generally insufficient rock exposure to determine whether they
represent faults or major joints. One pair of parallel lineaments,
located about 1,700 feet northwest of the intake structure is
particularly suggestive of a fault zone. Their origin is uncertain; if
they are the surface expression of a fault, the zone may contain highly
fractured and crushed rock up to about 200 feet wide along the proposed
tunnel alignment.
3.1.3.3 Tunnel-Bradley Lake River Fault Zone
At a distance of approximately 3,900 feet from the intake, the tunnel
alignment crosses the Bradley River Fault zone. The main trace can be
followed for several miles along a trend of about N15°E. The fault is
mantled by colluvial and glacial deposits, but is believed to be nearly
vertical because of its linear topographic expression. Exposures
elsewhere along the Bradley River Fault have suggested that the main
fault trace can have a gouge zone of finely pulverized material that is
up to 50 feet wide, with sheared argillite extending another 50 to 75
feet on either side (Dowl Engineers, 1983).
The Bradley River Fault zone was explored by boring SW83-2, which was
drilled perpendicular to the fault trace at an orientation of N75°W and
2-379-JJ 3-7
0 at an angle of 45 • Drilled to a depth of 262.3 feet, the boring
penetrated two shear zones at 47.4 -62.0 feet and 138.0-175.6 feet,
possibly representing branches of the fault.
From the surface to a drilled depth of about 30 feet, loose gravelly
sands with cobbles and boulders were encountered above bedrocK.
Striations observed on a cobble suggested that these materials are, at
least in part, glacial.
Beginning at the top of bedrocK, shear-foliated cherty argillite was
encountered, and encompassing the two shear zones, continued to a
drilled depth of about 197 feet. This rock is closely jointed to
locally very closely jointed.
Below a depth of 197 feet, alternating zones of graywacKe and chert
were encountered, with local zones of cherty argillite and foliated
argillite. Joint spacings in these materials increase to moderately
widely spaced joints when argillite materials are not significantly
present.
It is possible that additional shear zones exist to the east of the
upper one encountered in boring SW83-2. The material observed in
similar zones is predominantly brecciated argillite rock containing
clasts of chert. Locally the rocK has been reduced to fault gouge
consisting of breccia fragments in a clayey silt matrix.
The cherty argillite adjacent to the shear zones is generally very
closely jointed and the argillite faces adjoining shear planes are
extremely slickensided, often containing crushed rock fragments as
breccia and gouge.
The amount and sense of displacement along the Bradley River Fault zone
is not well established. Slickensides rake from 0 to 30° along the
2-379-JJ 3-8
fault suggesting a vertical component of up to 400 feet associated with
the 1,000 feet of apparent horizontal displacement. Horizontal offset
of a dacite dike tends to confirm this.
A multi position, rod-type extensometer was installed in Boring DH-10EX
by the COE. This boring crosses the Bradley River Fault and is located
about 1250 feet (380 meters) north of the point where the presently
proposed tunnel alignment intersects the fault. The extensometer was
installed on December 13, 1980.
recorded to date.
No significant movement has been
3.1.3.4 Tunnel-Bradley River Fault Zone to Bull Moose Fault Zone
Northwest of the Bradley River Fault zone, the tunnel alignment crosses
the highest elevations and best exposed bedrock exposures along its
route. This area is underlain predominantly by foliated argillite,
with lesser amounts of massive argillite, graywacke, and a single large
dacite dike. Much of the foliated argillite contains nodules and thin
discontinuous layers of chert comprising about 10 to 20 percent of the
volume of the rock. A few massive lenses of very closely fractured
chert up to 10 feet wide were also found interspersed with the foliated
argillite in this area. The foliation in the argillite and cherty
argillite strikes from N-S to N20°E and typically dips greater than
about 75 degrees. The dacite dike, although not exposed on the
alignment itself, appears to cross the proposed tunnel alignment along
a N80°E trend with a nearly vertical dip. For tunneling purposes this
rock will probably behave similarly to the massive argillite or
graywacke.
Bedrock outcrops along this segment of the tunnel alignment tend to be
widely to very widely jointed. Hundreds of short, linear, soil-filled
depressions can be seen in this area, many of which are presumably the
surface expression of bedrock joints and/or minor faults. Unfortun-
ately, however, without better rock exposure it is not possible to
distinguish which of these features are faults or joints.
2-379-JJ 3-9
--•
Larger lineaments, also common in this area, present the same problem
for attempts to define their structural significance. A series of
lineaments, occupying an area about 1,000 feet wide, located east of
and subparallel to the Bull Moose fault zone are possibly the surface
expression of smaller faults associated with the main fault trace, but
exposures are insufficient to conclusively determine their origin. In
spite of relatively good rock exposure in this area, it was not
possible to determine conclusively whether these represent minor faults
or prominent joint sets. In either case, exposures limit the width of
these apparent discontinuities, at the surface, to less than about 10
to 15 feet where they cross the tunnel alignment.
3.1.3.5 Tunnel-Bull Moose Fault Zone
The main trace of the Bull Moose fault zone is located approximately
9,800 feet northwest of the tunnel intake. It is expressed as a
narrow, topographic notch with a 200 feet high, steep west wall. This
area is densely vegetated and rock is exposed only in small isolated
outcrops. No exposures of the crush zone in the fault were found, but
relatively undeformed rock on either side of the main fault trace
indicates that this zone must locally be less than about 50 feet thick.
The tunnel alignment crossing of the Bull Moose Fault was explored with
boring SW 83-4. Drilled at an orientation of N80°W and an inclination
of 45°, this boring was carried to a depth of 206.2 feet .
Bedrock was encountered after only 4. 2 feet of penetration, and the
shear zone of the Bull Moose Fault was encountered at a drilled depth
of about 146 feet. Random alternating zones of graywacke, argillite,
and chert, as well as mixtures of these lithologies were logged within
the depth explored.
The shear zone of the Bull Moose Fault was encountered from a depth of
about 146 feet to 154 feet in the boring (horizontal width of 6 feet).
The brecciated argillite and graywacke in this zone is locally sheared
2-379-JJ 3-10
to silty sand and zones of clayey gouge. The rocks adjacent to the
shear zone, argillite above and chert below, are highly fractured with
considerable shear deformation.
The vertically projected location of the shear zone encountered in
boring SW83-4 is consistent with the mapped location of the fault trace
for a near-vertical fault plane.
A multiposition, rod-type extensometer was installed in Boring DH-17EX
by the COE. This boring is located about 500 feet (152 meters)
south-southeast of the point of intersection of the proposed tunnel
with the Bull Moose Fault. The boring was angled to cross the fault.
The installation was made on December 15-17, 1980. No movement has
been noted.
3.1.3.6 Tunnel -Bull Moose Fault Zone to Powerhouse Site
The bedrock exposure is much more limited along this segment of the
tunnel alignment than it is to the southeast. This is particularly
true to the northwest where forest and soil cover mantle all but a few
small isolated rock outcrops. The available exposures indicate that
this section of the tunnel alignment is underlain predominantly by
foliated and massive argillite. Cherty argillite and graywacke crop
out in relatively small amounts, although boring data indicate that
these rock types are more common than their surface exposure suggests.
The predominance of argillite is also indicated by natural outcrops
visible 1000 -1500 feet southwest of the tunnel alignment in a gully
which roughly parallels the alignment.
The recognizable structural trends in this area conform to those
elsewhere along the tunnel alignment. Foliation in the argillites is
consistently oriented at N-S to N20°E. Jointing is widely to very
widely spaced in most exposures, with a dominant strike of N75-85°
North.
2-379-JJ 3-11
A multiposition, rod-type extensometer was installed in Boring DH-13EX
by the COE. This boring is located about 700 feet (213 meters)
southwest of the presently proposed tunnel alignment. The instrument
was installed on December 11, 12, 1980. Initially, movement of the
reference head resulted in false readings at the shallow anchor point.
No significant movement has been noted at the two deeper anchors.
Based on data from surface mapping, borings, field instrumentation, and
laboratory tests it has been concluded that geologic conditions are
adequate for construction of the power conduit system. It is further
considered that it is feasible and preferable to excavate the tunnel
using a tunnel boring machine.
3.1.4 Powerhouse
The proposed powerhouse location is situated on a topographic bench
above the Kachemak Bay tidal marsh. This bench is underlain by rock at
shallow depth as indicated by exposures along the shoreline bluffs.
However, with the exception of the bluff exposures and outcrops along a
stream 500 feet to the south, the bedrock is almost completely covered
by a veneer of soil. A joint rosette was prepared based on
measurements made along the bluff. Based on these exposures and
previous borings drilled to the south along the stream channel, the
powerhouse site appears to be underlain by fractured argillite and
lesser amounts of fractured graywacke. A dacite dike also occurs in
the area and was seen only at a single exposure observed near the
alternate COE Francis unit portal location.
A hand-dug test pit was made in the area of the portal for the
alternate COE powerhouse location. Shallow bedrock was confirmed at
this site below about 1 to 2 feet of overburden material. The dacite
bedrock encountered in the test pit is similar to other outcrops of
dacite dike rocks observed in the Bradley Lake Project area. Although
the lateral extent of this material at the powerhouse site is not
known, its width would not be expected to be great.
2-379-JJ 3-12
Although the rock is typically fractured, it is considered satisfactory
as a foundation material for the powerhouse. Higher cut slopes, such
as above the power tunnel portal, may require some slope protection to
control nuisance-level ravelling.
3.1.5 Transmission Line
For purposes of delineating types of structure foundations, the route
of the 115 kV transmission lines, from the Bradley Lake powerhouse to
the tie into the HEA 115 kV transmission line (Bradley Junction), may
be divided into three distinct segments.
The first segment, from the powerhouse to the Fox River and Sheep Creek
deltas, approximately 6 miles in length, traverses a heavily forested
area along the lower slopes of the Kenai Mountains. The second
segment, across the delta at the head of Kachemak Bay, is approximately
3 miles long over open terrain. Toward the northwest, the third
traverses a flat plain for about 10 miles from the delta to the tie at
Bradley Junction.
Information has been gathered from various sources including: a
helicopter overflight of the area; two geologic ground reconnaissance
reports of the Bradley Lake Project which concentrate on the dam and
powerhouse sites; aerial photo interpretation of false-color infrared
photographs of the line route; a subsurface investigation at McNeil
Creek (a site located some 10 miles south of Caribou Lake resting on
the same geologic surficial deposits as exist along the route); and
some soil exploration using a hand probe. A brief description of the
three line segments follows.
In the first segment from the powerhouse to the delta, the terrain is
heavily wooded and covered with thick underbrush for a distance of
approximately 5.9 miles. From all indications, this part of the line
will be mostly in hard rock covered by shallow overburden consisting of
organic material and gravelly till. Peaty bogs in undrained
depressions and talus deposits of relatively loose granular material
may be encountered.
2-379-JJ 3-13
In the second segment beyond the mountainous region, the line traverses
the Fox River and Sheep Creek deltas, a distance of approximately 3.4
miles. The crossing is located beyond the reach of the tidal waters of
Kachemak Bay so inundation is unlikely unless the area subsides, as has
happened during previous earthquakes.
Previous investigations have shown that the intertidal and deltaic
areas along the shore consist of alluvial deposits overlain by up to 6
feet of clay. Based on photo interpretations it is expected that the
soil outside the tidal reach, will be alluvial deposits of relatively
loose to compact silty sands, gravels, and cobbles.
In the third segment, the longest segment of the transmission line
(approximately 9. 7 miles), the line is situated on a peneplain of
relatively flat relief. Geologic maps show two main formations in this
part of the Kenai Peninsula, the sandstones and siltstones of the Kenai
group and the overlying Quaternary surficial deposits. It appears,
from studies of the aerial photographs, that the surficial deposits are
relatively thin. Marshy areas surrounding Caribou Lake are extensive
and consist of peat and soft organic silt.
Transmission structures located outside the wet areas will be founded
in a sandy silt or silty sand soil. The previously mentioned
subsurface investigation at McNeil Creek revealed a layered system of
silty sand and sandy silt with traces of some gravel. To a depth of
approximately 10 feet, the deposits are relatively compact and increase
in density at greater depths. Assuming similar soils exist in the
transmission corridor area, there should be no difficulty in providing
suitable foundations for the directly embedded pole structures.
A site investigation was carried out to accumulate soil information for
preliminary selection of anchor types. This procedure was accomplished
by performing soil test probe readings and relating these readings to
general soil classifications for determining anchor holding powers.
2-379-JJ 3-14
For Segment 1, soil probe readings were taken at two locations. The
first, on a bluff near the Bradley River, consisted of three test
probes. The second, near the delta prior to leaving the timbered area,
consisted of three test probes.
For Segment 2, one soil probe reading was taken in at the edge of the
Fox River.
For Segment 3, soil probe readings in were taken at two locations. The
first, in a swamp near the proposed airstrip, consisted of one test
probe. The second, on a knoll southwest of Caribou Lake, and
approximately 3 miles east of the transmission line tie with the Homer
Electric Association, consisted of three test probes.
The results and summary of the findings of all the probe readings are
included in Appendix B of the License Application. Results indicate
that the proposed transmission line corridor is suitable for routing
and construction of the transmission line.
3.1.6 Barge Dock
A boring performed in the area of the barge dock, SW 83-3, was
advanced using rotary wash techniques with a Simco 2400 drill rig.
Samples were obtained at the base of the advanced casing with either a
3" O.D. thin-wall sampler (Shelby Tube), or a 2" O.D. split-spoon
sampler driven by a 140-pound hammer falling 30 inches onto the drill
rods (Standard Penetration Test). Torvane shear tests and pocket
penetrometer tests were performed on each Shelby Tube in the field. In
addition to the sampling of Boring SW 83-3, in situ vane shear tests
were performed at two depths in the fine-grained material.
Adjacent to boring SW 83-3 an additionai shallow boring, numbered SW
83-3A, was drilled specifically to obtain Shelby Tube samples. All
samples obtained from the barge dock location were sealed and returned
to the laboratory for testing.
2-379-JJ 3-15
The potential stability of the soils in the area of the barge dock
location was evaluated by a laboratory testing program on samples from
the single boring location in that area. These soils consisted of soft
to stiff silty clay and clayey silt overlying silty and clayey sands.
The sensitivity of the fine grained soils was calculated from the
results of natural and remolded in situ field vane shear tests,
laboratory Torvane tests, and unconsolidated-undrained triaxial
compression tests. Details of the laboratory tests are available. In
general, sensitivity ratios between 3.0 and 8.6 were measured. In one
case, a value of 1. 2 was obtained. This may be anomalous since the
water content of the remolded sample was 3 percent below the natural
content. Unconsolidated/undrained triaxial test maximum unit stresses
at 20 percent strain were as follows:
Undisturbed
5 psi
13.5 psi
18 psi
Remolded
3.5 psi
5 psi
7 psi
Plastic limits ranged between 17 percent and 23 percent, while liquid
limits ranged between 24 percent and 32 percent.
It appears that soil conditions are adequate to accommodate the barge
dock under normal conditions. It should be noted that it would
probably be impossible to prevent slumping of this material if
subjected to the forces of a large or major seismic event.
The test results from soils in the vicinity of the proposed barge dock
are considered suitable for evaluation of feasibility. however,
additional borings and tests were conducted during the design phase.
2-379-JJ 3-16
3.1.7 Access Roads
The data presented below were obtained along the general alignment of
the access facilities proposed in the License Application.. It is
expected that some minor alignment variations will occur during final
design.
A geologic reconnaissance mapping program utilized ground traverses
along a brushed and surveyed line and in selected accessible areas.
Aerial photographs and helicopter reconnaissance were used in
inaccessible areas. Bedrock outcrops were mapped with particular
attention to rock type and rockmass conditions that could influence
road construction (i.e., hardness, weathering, joint altitudes, joint
spacing, and foliation). Areas of talus, till, and alluvium, were
mapped and estimates were made of the character and depth of surficial
overburden. Visual estimates were also made on the amount of flow
occurring in streams crossing the alignments.
Seismic refraction surveys were used to evaluate the depth of
overburden material over bedrock, to assess the types of material below
the surficial cover and to evaluate the rippability of the rock mass.
Seismic refraction lines were generally laid out parallel to the center
line of the road alignment. In some cases line locations were adjusted
to minimize the impact of complex topography that could cause
interpretative difficulties. Despite these precautions, irregular
topography and surface weathering caused large amounts of scatter in
the seismic refraction data. Usually several inches of soft surface
material was removed to place the geophones on rock or firm soil. The
geophones were placed at water level in the bogs and mudflats.
Two simplifying assumptions were made in the interpretation of the
seismic refraction profiles:
2-379-JJ 3-17
o The upper weathered rock/soil layer, whose velocity varies between
1,000 and 2,000 feet per second, is assumed to have a constant
1, 300 feet per second velocity for all lines. This value is
fairly typical and results in no significant errors in depth
calculations.
0 All profiles were interpreted as simple two layer cases. This
results in some errors in the profiles which show a continuous
velocity increase with depth. In these cases, velocity errors of
+30 percent may occur.
The depth of penetration for the profiles in this investigation varied
between 30 and 50 feet.
After completion of the geologic mapping and the geophysical surveys,
soil boring sites were selected to assess the physical characteristics
of the near-surface soils. The soil borings also aided in geologic and
seismic interpretations.
Holes were drilled to a depth of 10 feet or to refusal using a
hand-operated, gasoline-powered auger. A post hole digger was more
effective in the higher elevations where cobbles impaired the use of
the power auger. Along Kachemak Bay, caving and water-saturated soils
limited the depth of drilling and sampling using the hand-operated
drilling equipment. Soils from each boring were logged and a sample
obtained of the most prominent soil horizon in each boring. Selected
samples were analyzed in the laboratory to confirm field
classifications.
The alignment may be divided into three general geographic areas:
1) the high-altitude lakes adjacent to Bradley Lake itself; 2) the
intertidal-delta area along Kachemak Bay; and 3) the forested area
located between the two previous regions.
2-379-JJ 3-18
Topographically, the high-altitude lakes area consists of rounded hills
or knobs of varying sizes. This area contains occasional steep cliffs
and several small lake basins. The vegetation in this area is
predominantly grass, low alpine brush, and patches of alders. Timber
stands are usually small and spotty. Bedrock is exposed in
approximately 20 to 25 percent of the area. Except for local
occurrences of till in valley bottoms and some talus on slopes below
steep bedrock outcrops, most of the high-altitude lake area has a very
shallow colluvial or soil cover over bedrock. Although access is
occasionally restricted by heavy patches of alders, the relatively open
nature of the area allows for direct observation of geologic
conditions. Unfortunately, the shallow soils and sediments that occur
in the area usually contain cobbles and boulders, making penetration
with hand-operated soil boring equipment difficult.
In the intertidal-delta area of Kachemak Bay, most of the road
alignment crosses the soils of the intertidal flats and the delta of
Battle Creek. These areas are generally grass covered and open except
for local stands of trees. Although very little of the proposed
alignment crosses bedrock in this area, bedrock conditions are
generally well exposed in the cliffs along the intertidal zone. The
intertidal and deltic deposits were soft enough to be easily penetrated
with an auger. However, groundwater made it difficult to keep the
borings open.
The forested area was the most difficult of the three areas to study.
The dense cover of trees made access by helicopter impossible and
aerial photography nearly useless. The dense trees also made locating
the proposed alignment from the ground nearly impossible without a
surveyed and brushed line. Few outcrops occur in the area because of
the heavy vegetation and the existence of a thick organic soil mat. The
few outcrops that do occur are generally located in vertical cliffs.
In the forested area the depth to bedrock varies significantly
depending largely on the topographic conditions.
2-379-JJ 3-19
In general, a variable thickness (0 to 20 feet) of overburden soils
overlie bedrock or other stronger materials. The overburden soils
consist of two major categories: 1) primarily granular soils
consisting of sands, silty sands, gravels, cobbles and boulders (till,
talus, alluvium, and colluvium). and 2) soft clays, organic silts,
peat, and other organic soils (intertidal deposits and bogs). The
bedrock consists primarily of argillite, graywacke, metaconglomerate,
and igneous dikes. The considerations depending on rock types are
rippability of rock, need for blasting, and stability of rock cut
slopes.
The primary considerations for the soils are the suitability as fill
material, load supporting capacity, and settlement under load.
Bedrock will generally be encountered at shallow depths for major
portions of the alignment. Generally, the bedrock is expected to be
hard with seismic velocities in excess of 9,000 feet per second. This
. means that ripping will generally be difficult to impossible in most
bedrock areas and that blasting will probably be required. The
blasting of the massive graywacke will produce blocky material and
could produce oversized boulders requiring secondary shots, depending
on the degree of jointing and the blast design used. Although the
intrusive dike rock is a different rock type from the graywacke, its
engineering characteristics are expected to be similar and will
probably not require any different treatment during construction.
Locally, some of the argillite and metaconglomerate were weathered
(seismic velocities of 7,000 feet per second) and may be marginally
rippable with the heaviest equipment. However, the majority of this
rock probably will require some blasting. Light shots may break up the
argillite rock sufficiently to allow some ripping.
General comments can be made about expected cut slope stability. The
stability of the cut slopes will be a function of the type of material
and the orientation of the cut with respect to foliation, joints, and
other rock structure attitudes. Cut slopes that cut the foliation in
2-379-JJ 3-20
0 argillite or metaconglomerate at 90 should have few problems except
for possible local ravelling of the rock. However, the closer the cut
parallels the foliation attitude the more likely stability problems
will occur.
Joints in graywacke cuts may cause local block failure problems
depending on the orientation of the cut slope with respect to the joint
attitudes and the frictional resistance along the joint surfaces.
Soil cover consisting of predominantly granular materials such as
sands, gravels, cobbles, sandy and clayey gravels belonging to till,
talus, alluvium, and colluvium geologic units are likely to provide
firm foundations for the road bed or fill. It is anticipated that
near-surface organic material and vegetation will be stripped and
wasted. Road construction through talus, and possibly in some cases
till, may be slowed by logistics of breaking large boulders or moving
them to offsite disposal ireas.
In some areas adjacent to lakes and other depressions bogs have formed
in which silty, organic strata may be present to depths on the order of
15 feet. The soils in the intertidal deposits are also organic rich
clays and silts. These soils are likely to be soft and highly
compressible and may be subject to bearing failure and long-term
settlement depending on the heights of fill placed on them. The
bearing failure would likely result in mud waves and displacement of
soft material under the weight of the fill. Consequently, these
materials may have to be removed by excavation or displacement. If some
of the clayey organic material are left beneath the fill, long-term
settlements are likely to result and will be considered in the road
design. Quantities of fill material will be estimated by taking into
consideration possible removal and replacement of these soft soils.
Alluvium, till, and talus should be easily excavated with conventional
equipment. Larger boulders in talus and in tills may need blasting.
2-379-JJ 3-21
The access road routes are considered suitable given the following
considerations:
o In areas of exposed or shallow bedrock, road cuts will require
blasting. The magnitude of the road cuts will be minimized as
much as possible by placing the final road alignment in valley
bottoms. The valley bottoms generally contain the granular
deposits which provide an easier material to work with and will
require less need for major terrain alteration.
o Where the alignment crosses bogs and intertidal clays, analyses
will be made to assess stability and the magnitude and potential
impact of settlement.
o A detailed geological/geotechnical survey of the final route will
be made on the ground to verify the information presented. In
addition, more route specific data will be obtained on the final
alignment for determining volumes of rippable material, material
needing blasting, and available fill materials. Where
appropriate, route specific data will also be obtained for cut
slope stability analysis in order that adequate slope angles or
other stabilizing measures can be properly designed.
3 .l. 8 Airstrip
Soil conditions at the airstrip are anticipated to be similar to those
at the barge dock, described above. Since the site is somewhat closer
to the mouth of the Bradley River, slightly coarser-grained materials
may be encountered. No subsurface exploration has been done at this
location, however subsurface exploration is planned during the final
design phase.
3.1.9 Borrow Area
A moderately extensive amount of fluvially transported glacial sand and
gravel has been deposited in the typical fan shape delta of the Martin
River. This material source covers a 288-acre area and was sampled in
2-379-JJ 3-22
11 locations by hand dug test pits to an average depth of 1 foot each.
Both laboratory test results and microscopic examination of this
material source shows it to be acceptable for concrete aggregate as
well as other types of construction materials. Access to the source
will be by a temporary haul road approximately 1.5 miles in length from
the main Project access road.
3.2 EXECUTIVE SUMMARY OF THE FINAL SITE CONDITIONS REPORT OF
GEOTECHNICAL FIELD INVESTIGATIONS 1984 and 1985 PROGRAMS
The figures referred to in this executive summary are in the Final Site
Conditions Report of Geotechnical Field Investigations for the Bradley
Lake Hydroelectric Project 1984 and 1985 Programs.
Geologic and geotechnical field investigations were performed at the
Bradley Lake Hydroelectric Project Site by R&M Consultants, Inc. during
the summers of 1984 and 1985. The 1984 (Phase I) investigations were
conducted for the purpose of development of necessary geotechnical
information prior to proceeding with design. The Phase II -1985
program was performed for the purpose of gathering additional pertinent
geotechnical information necessary for the preparation of construction
bidding documents.
The field program consisted of geologic mapping, seismic surveys,
borehole drilling, test pit excavation and associated field testing.
The geologic mapping program was desiged and carried out at the sites
of various proposed facilities in order to define the geologic
conditions present, provide a basis for extrapolation of borehole data,
and provide ground truthing and control for the seismic refraction
surveys. The seismic refraction surveys were performed in order to
evaluate the depth of overburden material over bedrock and to assess
the general soil type and consistency of the subsurface material.
Seismic reflection surveys were conducted in Bradley Lake to estimate
sediment thickness, character, structure and slope. The borehole
drilling program and field testing provided site-specific information
2-379-JJ 3-23
for use in the design of project facilities. A total of 139 separate
boreholes were drilled during the 1984 and 1985 programs, totalling
approximately 8,740 lineal feet.
Laboratory testing of soil and rock samples obtained during the field
mapping and drilling programs was undertaken for the purposes of
material classification, evaluation of engineering properties and the
assessment of materials for suitability as concrete aggregate and
riprap. Testing was performed in accordance with the need for
engineering data essential for the design of the proposed facilities.
In order to maintain continuity of data and information developed in
the past by others, the use of "Project Datum" for referencing
elevations has been continued. Therefore, all elevation references
throughout this report are given in Bradley Lake Project Datum, as
developed in the Horizontal land Vertical Control Survey and
Topographic Mapping performed in 1984/1985 by R&M.
This report provides a summary of the scope of work, the methods used
in completing both Phase I and Phase II field and laboratory studies,
and a discussion of our findings at each of the proposed facilities.
The Appendices contain data and seismic survey profiles developed in
the course of the investigations.
3.2.1 Regional Geology
The Bradley Lake Hydroelectric Project site is located in the McHugh
Complex, which is composed of metaclastic and metavolcanic rocks of
Cretaceous age. The predominant rocks in the Bradley Lake area are
graywacke and argillite; metatuff, greenstone and chert. These
lithologies were intermixed and greatly deformed as they were accreted
onto the North American Plate. A brief discussion follows of the
conditions present at each project feature.
3.2.2 Dam and Spillway
The proposed damsite
knobs. A bedrock
2-379-JJ
crosses the Bradley River between two bedrock
ridge forms the intake structure site to
3-24
the southwest of the damsite. The knobs and ridges have a sandy,
gravelly soil cover, and the valleys between them contain up to 20 feet
of glacial, alluvial and colluvial materials.
The area to the northeast of the Bradley River is composed
predominantly of graywacke with small infrequent argillite lenses. The
western three-quarters of the intake ridge, on the southwest side of
the river, is predominantly graywacke. Between these massive graywacke
outcrops, in a band trending roughly north-northw~st, the bedrock
consists of mixed graywacke and argillite.
R&M drilled 19 boreholes in the damsite area. Rocks encountered in the
boreholes closely matched those identified during surface mapping. The
boreholes drilled in the east abutment, diversion tunnel, spillway and
in the river encountered mainly graywacke. Boreholes adjacent to the
west side of the river and in the saddle area on the eastern portion of
the intake ridge contained mixed argillite and graywacke in varying
percentages. The west abutment is located in argillite and the intake
will be excavated in graywacke. In general, all bedrock encountered in
the damsite area was fresh to slightly weathered, hard and exhibited
only rare open joints or fractures.
3.2.3 Power Tunnel Alignment
The power tunnel, which will extend approximately 19,000 feet from
Bradley Lake to the powerhouse at the tidal flats of Kachemak Bay
encounters diverse geologic conditions. Site investigations including
geological mapping along the alignment and drilling of boreholes in the
vicinity of the gate shaft, inclined shaft, Bradley River Fault zone,
Bull Moose Fault zone and downstream portal areas were performed.
Rock units mapped along the power conduit alignment consist of
argillite, graywacke, metatuff, chert, dacite and greenstone. All the
rock types have been greatly deformed and intimately mixed, probably as
they were accreted onto the continental margin by tectonic forces. The
complexly mixed melange character of the area may be the most
pronounced feature of the site geology.
2-379-JJ 3-25
Lithology data along the power tunnel alignment identifies the dominant
map units as graywacke and argillite with chert, each comprising almost
one third of the outcrops on the alignment. Argillite occurs mixed
with graywacke, metatuff, graywacke and chert, metatuff and chert, and
in a relatively pure form, making it the dominate overall lithologic
rock type. Massive chert, dacite, metatuff and greenstone each
comprise minor fraction so the exposures.
Geologic structures along the power tunnel alignment include foliation,
joints, fracture zones, shears and faults. Foliation is very well
developed in the argillite and most lithologies mixed with argilite,
0 and has a general trend of N-S to N20 E, with a near vertical dip.
Graywacke, greenstone and more massive metatuff do not commonly show
foliation. The more massive and competent rocks (graywacke, greenstone
and massive metatuff) shows longer, flater, more parallel joint
development than argillite and rocks mixed with argillite. Small
fracture zones and shears were observed 'in several outcrops and in the
borehole rock core throughout the power conduit alignment, and may be
expected to be a common occurrence. Numerous other small fractures and
shears are thought to be masked at the surface by vegetation,
colluvium, frost shattering and the overall texture of the rock.
The two largest, and only major geologic structures intersecting the
tunnel alignment are the Bradley River and the Bull Moose Faults. Each
of these structures has a length of several miles and is
topographically expressed as a linear valley. Each fault was
investigated by a deep, inclined borehole which penetrated fault slip
surfaces. The main fault zones of both the Bradley River and Bull Moose
features were interpreted to be over 100 feet wide and contained
several zones of gouge. Boreholes RM 19 and RM 21 penetrated the most
significant geological structures along the power tunnel alignment and
are therefore thought to portray the most highly fractured conditions
likely to be encountered in tunnelling.
2-379-JJ 3-26
A third deep borehole was drilled on the approximate alignment of the
inclined shaft. The inclined shaft boring did not encounter any major
geologic structures, but did penetrate several fracture zones and
thinner faults with clay coatings and gouge. It is probable that
portions of the alignment between the major Bradley River and Bull
Moose faults contain fracture zones and minor faults similar to those
identified in the inclined shaft boring, RM 18.
3.2.4 Powerhouse and Tailrace Area
The powerhouse site lies immediately adjacent to Kackemak Bay and
extends from tidewater to about 100 feet above sea level. The area was
densely forested with tall spruce. Semi-continuous bedrock outcrops
occur along the cliff at tidewater, but exposures are rarely seen
inland. Soil cover in the powerhouse area is generally 3 to 10 feet
thick, but is locally believed to reach 15 to 20 feet.
Outcrops along the cliffs at tidewater are composed of varying mixtures
of graywacke and argillite. Some of the argillite contains up to 10%
chert nodules. An exposure of greenish dacite porphyry extending 10
feet along the base of the cliff was noted directly below the
powerhouse site and in a test pit several hundred feet inland. Six
bedrock test pits, located 50 to 100 feet inland from tidewater,
exposed mainly graywacke with some argillite. Predominant joints at
the powerhouse trend N80E, and dip 80 degrees to the SE and N35E,
dipping 70 degrees to the NW.
Four boreholes were drilled at the approximate corners of the proposed
powerhouse site. Three of these boreholes, RM 71, RM 72, and RM 74,
encountered graywacke and argillite in varying amounts. At the fourth
corner, boring RM 75 was drilled into dacite to its total depth. This
dacite, when correlated with the observed outcrops, appears to be a
vertical or near-vertical dike ap-proximately 15 feet wide.
Five test holes drilled in the main power tunnel/mainfold intersection
area encountered mixed graywacke and argillite with some chert.
2-379-JJ 3-27
3.2.5 Access Facilities
The access roads from the Martin River to the lower construction camp
site and from the lower camp site to the airstrip are located primarily
on tidal flats and salt marsh. In a few places, where the road
traverses close to or across points or headlands, bedrock outcrops were
identified. Cherty argillite intermixed with graywacke was observed in
these outcrops. Dacite dikes were mapped along the west side of Sheep
Point. Soils on the tidal flats (at the barge access, airstrip and the
roads) consist predominately of clayey silt,
commonly with organics near the surface.
encountered along portions of the road.
silt, and fine sand,
Some glacial till was
Rock outcrops mapped on the access road between the lower camp and the
dam are composed of cherty argillite and graywacke, and minor dacite
dikes.
3.2.6 Middle Fork Diversion
A diversion dam is proposed on the Middle Fork of the Bradley River
near elevation 2200 feet. The course of the diversion generally
parallels contour lines southward to Marmot Creek. The area is above
treeline and contains drift and colluvium-filled valleys and small
bedrock knobs which outcrop as frost-shattered rubble.
Rock outcrops in the area are mostly argillite, and locally contain up
to 80% chert nodules. Many outcrops and rubble piles also contain
mixed graywacke and argillite.
Two boreholes, RM 1 and RM 2, were drilled to depths of 30 feet and 17
feet, respectively, in the diversion dam area. They encountered cherty
argillite with up to 80% chert, and minor graywacke.
3.2.7 Lower Camp and Staging Area
Soils in the staging and lower camp areas are typically sandy gravel
with traces of silt. The soils are interpreted as braided river
floodplain deposits.
2-379-JJ 3-28
3.2.8 Martin River Borrow Area
Soils in the Martin River Delta vary from sandy, cobbley, gravel to
gravelly sand with interbeds of sand and silt. The near surface
material in the delta generally consists of coarser gravel, with the
percentage of sand increasing with depth. Data obtained from field and
laboratory analysis indicates that average grain size decreases
downstream within the study area.
3.2.9 Battle Creek Borrow Area
Soils in the western portion of this proposed borrow area are similar
to soils found in the lower camp area. These soils consist of sandy
gravel with traces of silt. The soil is bedded and in general, gravel
content decreases and sand content increases to the north.
Occasionally silter soils were encountered in the areas adjacent to
this proposed borrow source.
3.2.10 Transmission Line
Twenty-four boreholes and four test pits were sampled along the
proposed transmission line alignment. The transmission line will
extend about 20 miles from the powerhouse to intertie with the
Homer-Soldotna line. The route will traverse up to five (5) separate
physiographic areas, including: the Uplands Plateau composed of
organic loess and glacial drift overlying poorly consolidated bedrock;
the Kachemak Bluffs where active, shallow skin slides expose poorly
consolidated sands, silts, gravel and coal of Kenai Formation; the Fox
River Lowland, composed of fluvial sands, silts and gravel with minor
organics; the Kachemak Bay Mud Flats composed primarily of silt with
some sand and a saturated surface organic layer; and the Kenai Mountain
Foothills and Landslide area where glacial till overlies bedrock of the
McHugh Complex.
2-379-JJ 3-29
BORINGS, GEOLOGICAL REPORTS,
AND LABORATORY TEST REPORTS
4.0 BORING LOGS, GEOLOGICAL REPORTS AND LABORATORY TEST
REPORTS
The following documents are included in Appendices A through K of
Volume 5 through 10 of the Application for License for the Bradley Lake
Hydroelectric Project. These contain the boring logs, geological
reports and laboratory test reports that are part of the License
Application.
Volume 5
A. DOWL Engineers (DOWL). Bradley Lake Project, Geologic Mapping
Program. DOWL, Anchorage, Alaska, January 1983.
B. Dryden & LaRue Consulting Engineers (D&L). Feasibility Study of
Transmission Line System, Phase 1, Bradley Lake Hydroelectric
Power Project, D&L, Anchorage, Alaska, August 1983.
C. Hinton, R.B. Soil Survey of Homer-Ninilchik Area, Alaska, U.S.
Department of Agriculture, Soil Conservation Service, July 1971.
Volume 6
D. Shannon & Wilson, Inc. (S&W).
Project, Geotechnical Studies.
September 1983.
Bradley Lake Hydroelectric Power
K-0631-61, S&W, Fairbanks, Alaska,
E. Stephans, C.D., Lahr, J.C., and Rogers, J.A., Review of Earthquake
Activity and Current Status of Seismic Monitoring in the Region of
the Bradley Lake Hydroelectric Project, Southern Kenai Peninsula,
Alaska. U.S. Geological Survey, Open-File Report 82-417.
2-379-JJ 4-1
Volume 7
F. Stone & Webster Engineering Corporation (SWEC). Bradley Lake
Hydroelectric Power Project, Feasibility Study, Volume I, SWEC,
Anchorage, Alaska, October 1983.
Volume 8
G. U.S. Army Corps of Engineers (COE). Bradley Lake Hydroelectric
Project, General Design Memorandum. COE, General Design
Memorandum No. 2, February 1982, Volume 1 of 2.
Volume 9
H. U.S. Army Corps of Engineers (COE). Bradley Lake Hydroelectric
Project, General Design Memorandum. COE, General Design
Memorandum No. 2, February 1982, Volume 2 of 2.
Volume 10
I. U.S. Army Corps of Engineers (COE). Final Environmental Impact
Statement, Bradley Lake Hydroelectric Project, COE, Alaska
District, August 1982.
J. Woodward-Clyde Consultants
Bradley Lake Access Road,
Alaska, November 1980.
(WCC). Geologic
Project No. 14844A,
Reconnaissance,
WCC, Anchorage,
K. Woodward-Clyde Consultants (WCC). Reconnaissance Geology, Bradley
Lake Hydroelectric Project. Project No. 41193I, WCC, Anchorage,
Alaska, December 1979.
To supplement the above, we are submitting as Appendix C -The Final
Site Conditions Report of the Geotechnical Field Investigations for
Bradley Lake Hydroelectric Project -1984 and 1985 Programs.
2-379-JJ 4-2
BORROW AREAS
AND QUARRY SITES
5.0 BORROW AREAS AND QUARRY SITES
5.1 BORROW AREA LOCATION
One borrow area has been located at the Martin River for embankment
fill and concrete aggregate:
The Martin River Borrow area is located in Appendix A, Exhibit F on
Plate 1 with details of the borrow area shown on Plate 18.
5.2 BORROW QUANTITIES
The Martin River Borrow has been designed based upon geotechnical field
investigations to be able to provide up to 1,250,000 cubic yards of
borrow material. The access roads have been designed in a manner which
balances cuts against fills. Based upon the Site Preparation Contract
requirements the Martin River Borrow would provide about 700,000 cubic
yards of gravel fill and surfacing material. The Martin River Borrow
area will be further developed during the Civil Construction Contract
for concrete aggregate and additional gravel fill and road surfacing
material.
5.3 QUARRY SITES
Two quarry sites are proposed, a rip rap quarry and the
quarry. The rip rap quarry will be developed during
Preparation Contract. The main dam quarry will be developed
the Civil Construction Contract.
main dam
the Site
as part of
The rip rap quarry is located on the access road between the
construction camp and the dam site. Approximately 160,000 cubic yards
of rip rap will be required.
The main dam quarry will be developed to become the intake for the
power tunnel. The main dam quarry will provide the necessary rock fill
for the dam and cofferdams.
2-379-JJ 5-1
STABILITY AND STRESS
ANALYSIS
6.0 STABILITY AND STRESS ANALYSIS
6.1 GENERAL
The design analysis has been completed on project features which are
part of the Site Preparation Contract.
These project features are:
o Diversion tunnel including intake structure (Section 6.2)
o Downstream channel improvement (Section 6.3)
The stability and stress analysis is being done now on the Bradley Lake
Dam and Spillway, the Middle Fork Diversion, the Power Tunnel and
Penstocks and the Powerhouse and other structures (Sections 6.4 through
6.6) that are part of the Civil Construction contract. The completed
stress and stability analysis of these structures will be included as
part of the Final Supporting Design Report for the Civil Construction
that will be submitted for Commission approval in January 1987.
6.2 DIVERSION TUNNEL INCLUDING INTAKE STRUCTURE
6.2.1 Description
The diversion tunnel, as shown in Appendix A, Exhibit F on Plate 10, is
designed to pass Bradley Lake flows downstream during construction of
the main dam and other associated structures. The tunnel will later
provide a means of lowering the level of the completed reservoir at a
controlled rate as required during the project life in an emergency
condition. The tunnel facilities will allow downstream minimum flow
releases for the maintenance of aquatic habitat in the Lower Bradley
River.
The diversion tunnel will be constructed in two phases,
Preparation Contract phase and the Civil Construction phase.
the Site
The first
or Site Preparation Contract phase consists of excavating the tunnel
2-379-JJ 6-1
and constructing the diversion tunnel concrete intake structure. The
tunnel downstream of the intake structure is to be left unlined during
the initial phase. The intake structure includes one set of two gate
slots and the upstream portion of the fish release piping. The flow
section at the portal inlet is rectangular with an arched ceiling. A
transition at the intake to a horseshoe shape is provided. Temporary
timber stop logs are available during the initial phase. If an
emergency situation in the tunnel should require its closure. the stop
logs will be lowered into the slots. The timber stop logs are designed
for use during low flows. Water is discharged into a pool located at
the exit of the tunnel. The side of the pool opposite the tunnel is
riprapped to resist erosion caused by the tunnel discharge during the
diversion flow. Water from the pool will discharge into the Bradley
River channel improvement area.
The Civil Construction Phase includes construction of a vertical shaft
at 120 feet from the tunnel outlet. The shaft will contain two high
pressure gates installed in a series. One gate will function as a
control gate and the second as a guard gate. The upstream portion of
the tunnel is lined with an 18-inch thick concrete lining. A steel
penstock will be installed downstream of the control gate and will
extend to the tunnel exit. Bulkhead gates will be provided during the
Civil Construction Contract to close off flow from the intake structure
to permit construction of the remainder of the structures.
Minimum downstream flow releases to maintain aquatic habitat in the
Lower Bradley River are through two steel pipes embedded in the
concrete floor of the tunnel. The two pipe intakes are located
upstream of the tunnel inlet. Minimum flow releases are controlled
with valves and a system of nozzles at the downstream end of the pipes
at the tunnel outlet. The capability is provided to adjust flow
releases in 5 cfs increments. To attain this incremen.tal flow. two
pipe manifolds are provided near the tunnel outlet with varying sizes
of control valves and outlets. The manifolds are housed in a concrete
structure at the tunnel outlet.
2-379-JJ 6-2
The intake structure, unlined tunnel. and downstream channel will be
capable of passing up to 4,000 cfs by open channel flow during the main
dam construction. The 4000 cfs flow corresponds to the routed flood
of record which was selected as the design flood for the construction
diversion.
The bulkhead gates are designed to close against the diversion flow of
approximately 500 cfs. The corresponding flow depth at the gate guide
is five feet. To minimize the total vertical force on the gates during
their lowering and raising, several design features are adopted.
Teflon coated seals, and stainless steel sealing surface and teflon
coated bearing blocks are provided. Seals against the sill are
arranged to minimize the gate hydraulic downpull forces.
6.2.2 Design and Analysis
The major features of the diversion tunnel are shown in Appendix A
Exhibit F Plate 10.
The design and analysis of the intake structure and diversion tunnel
was based on the Alaska Power Authority design criteria for the Bradley
Lake Hydroelectric Project included in Volume 2 of this Final
Supporting Design Report for the Site Preparation Contract and listed
below.
Geotechnical Design Criteria
Hydraulic Design Criteria
Structural Design Criteria
Site Preparation Contract
Main Dam Diversion
Main Dam Diversion
The following calculations are included in Volume 3 and 4 of this
"Final Supporting Design Report for the Site Preparation Contract."
2-379-JJ 6-3
Title
Geotechnical Calculations
Main Dam Diversion Tunnel Alignment and
Surface Excavation Stability
Design of Rock Reinforcement Support System
for Main Dam Diversion Tunnel
Stability of Temporary Rock Plug for Main
Dam Diversion Tunnel
Rock Engineering/Design Parameters
Structurual Calculations
Diversion Intake Portal Analysis and
Design
Hydraulic Calculations
Calculate Water Surface Profile in Diversion
Tunnel
Quantities of Cofferdams and Comparison of
Quantities for Cost Estimate
Fish Bypass Pipe System
Forcing Frequency for Diversion Intake Pier
Lake Drawdown
Bulkhead Gate Operations
Water Surface Profile Diversion Tunnel
6.3 DOWNSTREAM CHANNEL IMPROVEMENT
6.3.1 General
Calculation No.
G(A)-03
G(A)-9
G(A)-17
G(A)-21
S-C-131-1
H-010
H-008
H-012
H-014
H-015
H-018
H-019
The layout and elevation of the diversion tunnel result in the need to
excavate the river channel downstream from the diversion tunnel outlet.
This downstream channel improvement is shown in Appendix A, Exhibit F
on Plate 13.
This downstream channel excavation allows a reduction in the size of
the downstream cofferdam for main dam construction and was made with
2-379-JJ 6-4
sufficient cross section and bottom slope to pass 4000 cfs without
causing a backwater effect in the tunnel at that flow. The channel is
excavated in rock and lining is not required.
6.3.2 Design and Analysis
The features of the downstream channel improvement are shown in
Appendix A, Exhibit F on Plate 13.
The design and analysis of the channel improvement was based on the
Alaska Power Authority Design Criteria for the Bradley Lake
Hydroelectric Project, included in Volume 2 of this Final Supporting
Design Report for the Site Preparation Contract Report and listed
below.
Hydraulic Design Criteria
Geotechnical Design Criteria
Main Dam Diversion
Site Preparation
The following calculations are included in Volume 3 and 4 of this
"Final Supporting Design Report for the Site Preparation Contract."
Geotechnical Calculation
Diversion Channel Alignment and Excavation
Hydraulic Calculations
Design Channel Downstream of Diversion Tunnel
Quantities of Excavation
Quantities of Cofferdam
Design of Channel Downstream of Diversion
Tunnel
Water Surface Profiles Downstream of Diversion
Tunnel
Riprap Design Bank Across Pool from Diversion
Tunnel Exit
2-379-JJ 6-5
Calculation No.
G(A)-15
H-003
H-004
H-008
H-016
H-017
H-021
Calculation No.
Hydraulic Calculations (Continued)
Relationship of USGS Gaging Station to Bradley
Lake Project Datum
Synthesize Flood of Record Inflow Hydrograph from
Recorded Outflow Hydrograph at Bradley Lake
Flood Routing -Flood of Record through
Bradley Lake and Diversion Tu~nel
6.4 MAIN DAM
6.4.1 Description
H-024
H-029
H-033
A concrete faced rockfill dam is selected as the most technically
feasible and economically suitable structure for increasing the storage
capacity of the Bradley Lake reservoir.
A plan of the dam and associated structures is shown in Appendix A,
Exhibit F on Plate 2. The layout and conceptual details of the dam are
shown in Appendix A, Exhibit F on Plate 3. The dam has a crest 18 feet
wide and 610 feet long at elevation 1190.6. It has a height above the
lowest average foundation level of 125 feet.
The axis of the recommended dam is approximately 520 feet downstream of
the natural lake outlet. This location and the axis orientation were
selected to best utilize existing topographic features and to minimize
the volume of rockfill in the embankment. The selected location also
makes effective use of previously obtained geologic data and allows for
the development of the embankment within the restricted area of the
river. The axis orientation offers good alignment for the upstream toe
slab, and results in toe slab construction without excessive three
dimensional discontinuities. In addition, the alignment balances the
upstream and downstream road access requirements for construction of
the dam.
2-379-JJ 6-6
6.4.2 Foundation Conditions
The dam will be founded on bedrock composed chiefly of alternating
sequences of argillite and graywacke. In situ rock visible at the
ground surface in the damsite area is all moderately hard to hard and
is considered adequate to support a rockfill dam. Surficial weathering
is generally confined to the upper few feet of rock; however, staining
on joints and fractures in the rock indicates these are potential
leakage channels from the reservoir. There will be adequate provisions
made to provide positive seepage cutoff and control.
A detailed description of the abutment and foundation conditions in the
dam area is included in Section 3.1.1.
6.4.3 Foundation Preparation and Treatment
The dam foundation must be stable under all conditions of construction
and reservoir operation, and must limit seepage so as to prevent
excessive uplift pressure, erosion of material, and loss of water. The
embankment will be founded on competent rock. All overburden and
unsuitable rock will be removed from beneath it. The near-vertical
right abutment will be sloped back beneath the upstream concrete face
slabs as necessary to provide a positive abutment contact and a gradual
transition between the embankment and bedrock for consideration of th
effect of embankment settlement on the face slabs. Any intensely
sheared and altered rock zones exposed during foundation preparation
will be treated. Beneath and immediately downstream of the upstream
concrete toe slabs these excavated zones will be refilled with dental
concrete, while under the main body of rockfill they will be protected
with filter, if necessary, and allowed to drain.
A grout curtain will be constructed under the upstream toe slabs for a
seepage cutoff in the bedrock. A triple row grout curtain is presently
anticipated. The maximum depth of the center grout line will be about
2/3H (where H is the maximum reservoir hydrostatic head at a particular
location above the dam foundation). The minimum depth of grout holes
will be equal to the width of the concrete face slabs. The grout holes
will be orientated to intersect major joint sets.
2-379-JJ 6-7
6.4.4 Dam Cross Section and Materials
The conceptual design of the embankment section shown in Appendix A,
Exhibit F on Plate 3 is conservatively developed with selected zoned
material to withstand hydrostatic, ice, earthquake, and other external
loads. The dam is developed using three zones of material compacted to
form upstream and downstream embankment slopes of 1. 6H: 1V. Zone 1,
forming the upstream face of the rockfill, consists of selected 6 inch
minus material. This zone is placed in 15 feet wide horizontal layers
of one foot lifts and is compacted with heavy steel drum vibratory
rollers. Zone 2 forms a highly pervious drainage band at the base of
the central section of the dam. This zone is composed of selected 6
inch to 24 inch material placed in 3 feet lifts and compacted with
vibratory rollers. Zone 3 is quarry material placed in 18 inch lifts
and compacted with vibratory rollers. Material placement within this
zone will be such as to direct the better quarry material to the
upstream half of the zone. Oversized material will be pushed to the
downstream face. The exact stone size and lift heights are in the
process of being finalized and may vary from the data given above
following final design.
Use of the proper material gradation in these selected zones, coupled
with controlled placing techniques and, proper spreading and
compacting, will result in an embankment that is strong and dense and
able to withstand the forces on the dam with minimum deformation. The
gradation of the material within the selected zones distributes contact
forces with smaller sized material occupying the voids between larger
rock pieces locking both into position. At the same time adequate
space is provided within the rockfill to ensure high permeability for
the drainage of seepage water. The rockfill embankment is developed in
an essentially continuous operation. Materials for its construction
are readily available from quarry sources adjacent to the structure.
The upstream face of the dam consists of a parapet wall, concrete face
slabs, and toe slabs. The concrete parapet wall, extending 4 feet
above the dam crest, is provided with a curved upstream surface to act
as a wave and ice deflector.
2-379-JJ 6-8
The impervious
concrete slabs.
50 feet wide
upstream face is formed by a series of reinforced
Central face slabs have been conceptually designed as
monoliths. Abutment face slabs are narrower and
articulated to accept greater deflections. The slabs are conceptually
designed to have a nominal thickness of 12 inches at the top, near the
parapet, varying linearly to a maximum thickness of 18 inches at the
lowest elevation of the dam. Concrete toe slabs are constructed to
connect with the face slabs and to form the watertight closure between
the upstream heel of the embankment and its rock foundation. Concrete
mixes particularly suitable for cold and harsh environments will be
used in the construction of these members, offering excellent
resistance to freeze-thaw action, ice buildup, and strains resulting
from seasonal temperature variations.
6.4.5 Static and Dynamic Stability Analysis
The preliminary slope stability analyses is included in Volume 4 of the
Preliminary Supporting Design Analysis of the Application for License
for the Bradley Lake Hydroelectric Project. The final stability
analysis will be completed in the Final Supporting Design Report for
the Civil Construction Report.
6. 5 SPILLWAY
6.5.1 Physical Description
An ungated concrete gravity ogee spillway is located on the saddle
feature of the right abutment approximately 150 feet east of the main
dam and along the same general axis alignment. The overall length of
the spillway including abutments is approximately 230 feet of which 175
feet is provided for the overflow crest. The height from foundation
level to the crest varies from 50 feet for the low spillway section to
30 feet for the high spillway section. The spillway has an upstream
sloping face and its concrete abutments will be rounded above the crest
for hydraulic efficiency. The crest is shaped and contoured to produce
gradually accelerating flow on the basis of a 10.6 feet design head.
2-379-JJ 6-9
Spillway discharges will be directed onto existing rock beyond the
spillway apron. A plan of the spillway with elevations and sections is
shown in Appendix A, Exhibit F on Plate 4.
6.5.2 Foundation Preparation and Treatment
The spillway is founded on competent bedrock with its concrete gravity
abutments keyed into the adjacent rocks. All overburden and unsuitable
rock will be removed from under the spillway and along the abutments.
It is estimated that a maximum of approximately 17 feet of overburden
will be removed.
A triple row grout curtain will be developed along the spillway below
foundation level and extended from the right to the left abutment. The
upstream and downstream grout rows will be developed for contact
grouting operations and the center row will provide the primary seepage
cutoff. The center row grout curtain will be designed to effectively
cutoff seepage at the abutments and to maintain cutoff continuity
between the spillway and the main dam.
For additional safety, a foundation drainage system is provided
downstream of the grout curtain. The system consists of vertical drain
holes drilled into foundation rock, a collector pipe, and a lateral
pipe to discharge seepage below the spillway chute. In addition,
provisions are made to access the drain holes for pressure monitoring,
cleaning, or re-drilling.
6.5.3 Stability Analysis
The preliminary stability analyses is shown in Volume 4 of the
Preliminary Supporting Design Report in the License Application for the
Bradley Lake Hydroelectric Project. The final stability analysis is
being designed at the present time and will be included as part of the
Final Supporting Design Report for the Civil Construction Contract.
2-379-JJ 6-10
6. 6 MIDDLE FORK DIVERSION DAM
6.6.1 Project Description
The Middle Fork Diversion dam is located approximately 1 mile north of
Bradley Lake in an adjacent drainage at elevation 2200 feet on the
Middle Fork stream. The Middle Fork Diversion facility is being
designed and the final design will be part of the Final Supporting
Design Report for the Civil Construction Contract. The design concept
that was part of the preliminary support Design Report are shown in
Appendix A, Exhibit F, Plates 11 and 12.
6.6.2 Foundation Conditions
The bedrock in the area of the Middle Fork Diversion Dam is
predominantly graywacke with argillite interbeds. Initial geological
and visual observations indicate that the Middle Fork stream bed at the
dam site consists of bedrock. Borings to further investigate the
foundation condition will be made during the design phase of the
project.
6.6.3 Foundation Preparation and Treatment
The dam foundation will be made stable under all conditions of
construction and reservoir operation, and will be designed to limit
seepage so as to prevent excessive uplift~·pressure, erosion of
material, and/or loss of water. The embankment will be founded on
competent rock. All overburden and unsuitable rock will be removed
from beneath it. A grout curtain will be constructed in the foundation
rock below the dam to reduce seepage and downstream uplift pressures.
6.6.4 Dam Cross Section and Materials
The dam will be approximately 140 feet long and 20 feet high rockfill
embankment.
Enbankment rockfill will be obtained from the required spillway
excavation. The rockfill will be placed in thin lifts and compacted
2-379-JJ 6-11
with heavy steel drum vibratory rollers. Due to the remoteness of
Middle Fork. Dam, this design was selected to provide the required
durability and ability of the dam to resist the elements.
6.6.5 Static Stability Analysis
The preliminary slope stability analyses is included in Volume 4 of the
Preliminary Supporting Design Analysis of the License Application for
the Bradley Lake Hydroelectric Project. The final stability analysis
is being done now and will be included as part of the Final Supporting
Design Report for the Civil Construction Contract.
6.7 POWERHOUSE
The powerhouse is being analyzed at this time and the foundation
conditions, the static and dynamic analysis will be a part of the Final
Supporting Design Report for the Civil Construction Contract.
6.8 REFERENCES
1. Newmark, N .M., Effects of Earthquakes on Dams and Embankments.
Geotechnique, Vol. 15, No. 2, 1965, pp. 139-160.
2. Sarma, S.K., Response and Stability of Earth Dams During Strong
Earthquakes. Misc. Paper GL-79-13, U.S. Army Engineer Waterways
Experiment Station, Vicksburg, MS, 1979.
3. Seed, H.B. and Idriss, I.M., Soil Moduli and Damping Factors for
Dynamic Response Analyses. Report No. EERC 70-10, Earthquake
Engineering Research Center, College of Engineering, University of
California, Berkley, CA, 1970.
4. Stone & Webster Engineering Corporation (SWEC). Slope Stability
Analysis (LEASE II) -User's Manual. GT-018, Version 02 Level 00.
SWEC, Boston, MA, August 1980.
5. Stone & Webster Engineering Corporation (SWEC). Seismic
Amplification Response by Modal Analysis (SARMA) -User's Manual
(Draft). GT-055, Version 00 Level 00. SWEC, Boston, HA, July
1983.
2-379-JJ 6-12
6. Woodward-Clyde Consultants (WCC). Report on the Bradley Lake
Hydroelectric Project Design Earthquake Study. wee. Anchorage J
AK, November 1981.
7. U.S. Dept. of the Interior, Bureau of Reclamation, "Design of
Gravity Dams," 1976.
8. U.S. Dept. of the Interior, Bureau of Reclamation, "Design of
Small Dams," Revised Reprint 1977.
9. National Research Council, Committee on the Safety of Existing
Dams, Water Science and Technology Board, Commission on
Engineering and Technical Systems, "Safety of Existing Dams -
Evaluation and Improvement", 1983.
2-379-JJ 6-13
BASIS FOR SEISMIC LOADING
7.0 BASIS FOR SEISMIC LOADING
7 .l GENERAL
A number of investigations of the seismicity of the Bradley Lake
project have been completed by the Army Corps of Engineers (COE), the
US Geological Survey (USGS), and Woodward-Clyde Consultants (WCC).
The USGS is conducting a seismic monitoring program in the vicinity of
the site. Their most recent summary report is presented in Appendix E
of the Application for License for the Bradley Lake Hydroelectric
Project.
7.2 SEISMOTECTONIC SETTING
The primary cause of seismic activity in southern Alaska, including the
site area, is the stress imposed on the region by the relative motion
of the Pacific and the North American lithospheric plates at their
common boundary. The Pacific plate is moving northward relative to the
North American plate at a rate of about 6 em/yr. causing the
underthrusting of the Pacific plate. This underthrusting results
primarily in compressional deformation which causes folds, high-angle
reverse faults, and thrust faults to develop in the overlying crust.
The boundary between the plates where the underthrusting occurs is a
northwestward-dipping megathrust fault or subduction zone. The
Aleutian Trench marks the surface expression of this subduction zone
and is located on the ocean floor approximately 185 miles south of
Bradley Lake. The orientation of the subduction zone is inferred along
a broad inclined band of seismicity, referred to as the Benioff Zone,
that dips northwest from the Aleutian Trench, and is approximately 30
miles beneath the Bradley Lake Site. Historically ( 1899 to date),
eight earthquakes ranging between 7.4 and 8.5 Richter magnitude have
occurred within 500 mi of the site.
2-379-JJ 7-l
Great earthquakes (surface wave magnitude M 8 or greater) and large s
earthquakes (greater than M 7) have occurred historically throughout s
the region and can be expected to occur in the future.
Bradley Lake is situated on the overriding crustal block above the
subduction zone and between the Castle Mountain fault to the north and
the Patton Bay-Hanning faults to the southeast on Montague Island; all
of these faults have documented Holocene or historic surface ruptures.
Because of the active tectonic environment, activity is probable on
other faults, which are also located in the overriding crustal block
and between the known active faults mentioned above, such as those
found near or on the project site.
Two faults of regional extent occur at or near the site. The Border
Ranges Fault trend southwest beneath Kachmak Bay and the Eagle River
Fault crosses the southeastern portion of Bradley Lake at about the
same trend. While no direct evidence of recent activity along these
faults is known in the site area, recently defined data indicates
recent activity on the Eagle River Fault near Eklutna (125 mi NE of the
site). Given the tectonic setting, it is reasonable to consider these
faults potentially active.
In addition to the nearby regional faults, the site is crossed by two
large local faults, informally called the Bradley River Fault and the
Bull Moose Fault, and a number of probable smaller faults. The
dominant trend is northeasterly, paralleling the regional trend. The
larger local faults, particularly the Bradley River, are probably
capable of independent earthquake generation while any of the local
faults could probably move in sympathetic response to earthquakes
generated by the regional faults.
It is therefore concluded that the site will probably experience at
least one moderate to large earthquake during the life of the proposed
project. The possibility of ground rupture exists but is much less
subject to prediction.
2-379-JJ 7-2
7.3 SEISMIC DESIGN
The seismic design criteria for the major project structures are
described in Section 2.1.2.8.
2-379-JJ 7-3
SPILLWAY DESIGN FLOOD BASIS
8.0 SPILLWAY DESIGN FLOOD BASIS
Probable Maximum Flood (PMF) and Standard Project Floods (SPF) for the
Bradley Lake basin and the Probable Maximum Flood for the Middle Fork
Diversion basin were computed by the Alaska District, Corps of
Engineers during its feasibility investigations of the project in 1979-
1982. The following summarizes the methodology, criteria, and results
of those studies as presented in its reports entitled "Design
Memorandum No. 1, Hydrology" dated June, 1981, and "Design Memorandum
No. 2, General Design Memorandum", dated February, 1982.
The Applicant has reviewed the methodology, criteria, and results of
the Corps of Engineers flood studies and finds these to be reasonable
and acceptable. Also, the Applicant has determined that the low level
outlet or powerhouse hydraulic capacities were not utilized in reducing
the PMF or SPF discharges, and will retain this approach when designing
the Project spillway structure.
8.1 STUDY METHODOLOGY
A mathematical model of the Bradley Lake basin was developed to compute
the PMF hydrograph. The watershed model was established using the
Streamflow Synthesis and Reservoir Regulation (SSARR) computer program
developed by the North Pacific Division, Corps of Engineers.
In order to verify the
characteristics of the
reconstituted using the
establish glacial runoff
simulation of the physical and hydrologic
basin, several historical floods were
SSARR program. In addition,
parameters, the model was also
to better
calibrated
against runoff from Wolverine Glacier, located 25 miles northeast of
Seward. Daily streamflow, temperature, and precipitation were
available at Wolverine Glacier, greatly improving the reconstitution.
Schematic diagrams of the basin models used for reconstitution of flows
for Bradley River and Wolverine Creek are shown on Figure F8.1-l at end
of Secion 8.0.
2-379-JJ 8-1
The Hydrometeorological Branch, National Weather Service (NWS),
developed probable maximum storm criteria of the Bradley Lake basin in
their report entitled "Study of Probable Maximum Precipitation for
Bradley Lake Basin, Alaska," dated May, 1961. Estimates from this
report were reviewed by the NWS in June, 1979 and found to be still
valid.
8.2 MODEL CALIBRATION
The SSARR watershed models for both the Bradley Lake basin and the
Wolverine Glacier basin were verified by comparing the computed and
observed discharge hydrographs at stream gauging stations on Bradley
River near Homer and on Wolverine Creek near Lawing. The following
events were selected for flood reconstitution studies:
o August -September 1974 (Wolverine Creek)
o 10-20 August 19058 (Bradley River)
~ 8-17 September 1961 (Bradley River)
o 10-30 September 1966 (Bradley River)
The streamflow hydrographs (observed and computed) for the above events
for Wolverine Creek and Bradley river are shown on Figure F8. 2-1 and
F8.2-2 at end of this section.
8.2.1 Computer Program Application
The basins were subdivided into subbasins as depicted in Figure FS.l-1.
These subbasins represent the glacial and nonglacial regions of the
basin, with the glacial areas further subdivided into elevation zones
in which temperature dependent processes can be simulated. Separate
basin characteristics were derived of the glacial and nonglacial areas,
and are illustrated on Figure F8. 2-3. Snowmelt and precipitation on
each of the subbasins were input to the model and losses simulated to
obtain the increments of excess water which were converted to surface,
subsurface, and base flow.
Moisture Index (SMI).
2-379-JJ
Total runoff is dependent on the Soil
8-2
8.2.2 Precipitation
Data from Homer and Seward were used as indices to precipitation.
Since these stations showed variation in daily precipitation in the
basin, station weights were adjusted on storm-by-storm basis to
simulate storm runoff volumes. Reconstitutions were therefore made for
individual rainstorms.
8.2.3 Temperature
0 Data from Homer, adjusted for a lapse rate of 2.9 F/1,000 feet, were
used as an index to basin temperature.
average daily temperatures.
8.2.4 Snow
Melt rates were based on
Since all reconstitutions were for rainfall events occurring in late
summer, it was assumed that all nonglacial areas were snow-free. The
snow covered area in each glacial elevation bank was set at 100
percent, with the snow water equivalent arbitrarily set at 300 inches
for each band to simulate the effect of the glacier. The temperature
index method was used for computing snowmelt utilizing a constant melt
rate of 0.098 inches/°F -day.
8.2.5 Losses
Losses were simulated for each time period in the program by the Soil
Moisture Index (SMI). Runoff is a function of the SMI, which varies
for each time period and which is derived from the SMI for the previous
period, runoff generated in the previous period, and the
evapotranspiration index. Both glacial and nonglacial areas assumed
high runoff percentage.
8.2.6 Separation of Runoff
The separation of total runoff into the components of flow is variable
in the computer program. On the nonglacial areas, the portion of water
input contributing to base flow decreases as the Base Flow Infiltration
Index (BII) increases. On glacial areas, there were initial minor
2-379-JJ 8-3
decreases in percentage of runoff converted to base flow, but base
flows were then held constant at 95 percent of total runoff, as it was
assumed that most melt and rainfall runoff would flow into crevasses
and emerge as subglacial flow. Although termed base flow, routing
phases and periods were set such that glacial "base flow" still
exhibited rapid runoff characteristics.
The number of phases and the time of storage per phase used in the
routings are:
Runoff Component
Surface
Subsurface
No. of Phases
4
4
Time of Storage/Phase (hrs)
3.3
10.0
Because the basin lacks any extensive soil cover, the
surface-subsurface split for nonglacial areas assumed that most runoff
occurs as surface flow. The base, subsurface, and surface flow for
each subbasin were routed and combined to yield the total subbasin
outflow. Subbasin outflows were combined with other subbasin flows to
produce the total runoff hydrograph.
8.2.7 Flood Reconstitutions
The Bradley Lake basin, because of its elevation, proximity to the Gulf
of Alaska, and exposure to storms moving into the Gulf of Alaska,
receives precipitation amounts exceeding those recorded at the coastal
weather stations. Because of the difficulties of verifying computed
hydrographs in early summer and in assigning proper precipitation
weights over an extended period of time, individual storms were
reconstituted for the August-September period (when rainfall is
greatest), adjusting precipitation weights until computed runoff
volumes matched observed runoff volumes.
The reconstitutions are shown in Figures F8.2-l and F8.2-2. They
follow the general timing and pattern sufficiently well to justify
2-379-JJ 8-4
applicat~on of the method to PMF derivation.
in the glacial runoff characteristics
Confidence can be placed
as derived from the
reconstitution for Wolverine Creek, where adequate data were available.
Runoff characteristics for the nonglacial areas of Bradley Lake were
estimated from hydrological reconnaissance studies, and are believed to
be fairly reliable due to the impervious character of the basin.
8.3 PROBABLE MAXIMUM FLOOD
The streamflow records for the Bradley River at the lake outlet
indicate that the maximum annual peak discharge normally occurs between
August 1 and October 31 from a summer rainfall flood. The National
Weather Service estimated that the probable maximum storm would occur
in either August or September. The probable maximum flood was
developed utilizing storm criteria for August developed by the
Hydrometeorological Branch, National Weather Service, with the 100-year
storm assumed as an antecedent rainstorm.
8.3.1 Computer Program Application
The SSARR model developed from flood reconstitutions was used for the
PMF determination for Bradley River. The SSARR model for PMF
determination of the Middle Fork Diversion was developed using basin
characteristics derived for the Bradley Lake basin.
8.3.2 Precipitation
The Hydrometerorological Branch, National Weather Service, determined
that the Probable Maximum Precipitation (PMP) would be a combination of
orographic and nonorographic rainfall occurring in either August or
September. The rainfall was distributed in 6-hour periods in the
manner prescribed by the NWS. The total 72-hour precipitation for the
PMF is 41.0 inches with a maximum 6-hour accumulation of 11.1 inches.
As the NWS indicated that air temperatures during the August PMP are
expected to be about 2°F higher than those during the September PMP,
the PMP is forecast for August.
2-379-JJ 8-5
A 3-day antecedent rainstorm was assumed to occur before the PMP storm,
using 100-year rainfall data taken from U.S. Department of Commerce,
Technical Paper No. 47 and Technical Paper No. 52. The antecedent
rainstorm was logged in 12-hour intervals to determine the sensitivity
of the PMF to the timing of the antecedent storm. Since the PMF is
relatively insensitive to the length of time between storm, a 48-hour
lag time between storm was taken as a reasonable time period, and used
in the derivation of the PMF.
8.3.3 Snow
Snowmelt was handled in the same manner as in the flood
reconstitutions. The temperature index method was used to compute melt
from the glaciers. It was assumed that nonglacial areas were
snow-free. The snow water equivalent for each glacial elevation band
was arbitrarily set at 300 inches.
inches/°F-day was used.
8.3.4 Temperatures
A constant melt rate of 0.098
The NWS report includes the temperatures to be used during the probable
maximum storm, and gives a temperature envelope to be used for the
periods before and after the storm. The highest temperatures in the
envelope were utilized to maximize snowmelt.
8.3.5 Ruonoff Separation and Losses
Separation of flow and losses during PMF runoff were simulated in the
same manner as in the flood reconstitutions.
8.3.6 Probable Maximum Flood Hydrographs
The PMF Hydrographs are being developed now for the Middle Fork
Diversion and the Nuka runoff into Bradley Lake. These hydrographs
will be part of the Final Supporting Design Report of the Civil
Construction Contract.
2-379-JJ 8-6
8.4 STANDARD PROJECT FLOOD
The Standard Project Flood (SPF) for the Bradley Lake basin is being
derived using the same initial basin conditions and antecedent
precipitation as for the PMF. Precipitation for the SPF is 50 percent
of the PMF and has the same distribution. The SPF inflow hydrograph is
being developed now.
8.5 SPILLWAY DESIGN FLOOD
The Spillway Design Flood (SDF) for the Bradley Lake basin is the
spillway discharge when the PMF is routed through the reservoir. The
most critical period occurs during late summer when the reservoir is at
maximum level and the probability of receiving the PMP is greatest.
The starting water surface is at spillway crest Elevation 1180.0. The
spillway is an uncontrolled ogee type with a crest length of 175+ feet.
The peak discharge of the PMF is being routed through the spillway now
and the results will be described in the Final Supporting Design Report
of the Civil Construction Contract.
2-379-JJ 8-7
1 ~~Ill'
Bradleyj
Lake
Surface
Bradley
Nonglacial,
Bradley Lake
Bradley River
at Lake Outlet
Bradley Glacial Bands
+ I. _:.__ ~ ---··· --1
"
'-/ /'
I 1220\
I \ J I ?..._..,
I // Adjusted
.,...--'(/ Middle Fork
(214 J '-.,./
Sign Change
(a) BRADLEY RIVER
Wolverine
Nonglacial
Wolverine Glacial Bands
+ I ------~ ~ nl
Wolverine Creek
near Lawing .
(observed)
8
Middle Fork
Glacial
Bands (b)WOLVERINE CREEK
LEGEND
0 BASIN OR SUBBASIN
0 COLLECT POINT
L. RESERVOIR SCHEMATIC OF
SSARR MODEL
'----------------------------FIGURE F8.1-1.----...
-· ,1, PLOT sTATION NAME STAll ON CHARACTER f\Ut'BER CGt\TROL C-~OLVERINE CREE" FLOW --CALCLLATED 11 0. 0 (; A-~OLVERINE CREEK FLO~ --CBSER~ED 110.: Q FLOW CFS 0. 1 0 0. 200. 300. 400. 500. 600. 700. BOO. .> T -2369 4 110. 20.00 26.00 32.00 38.00 44.00 so.co Sc.CO 62.00 6e.oo --236q 3 2.!0. o.o o.so 1.00 1 • 50 2.00 2.50 :!.00 :! .•5 0 4.00 1 ALG 74 1200 p 2 AUG 7ll 1200 p 3 Al!G 74 1200 . p 4 AUG 74 1200 p . . . ~~ . . T -5 AL:G 74 1200 p . • 6 At.;G 74 1200 p 7 AUG 74 1200 p . . • I . • 8 AL'G 74 1200 . p . . • T . . . • 9 AIJG 74 1200 p • . . • . . • 10 AL'G 7li 1200 p 11 AL'G 74 1200 p 12 AUG 7li 1200 p . . . ~::::-... . • T 13 AUG p . . . . . o I • 14 AUG 74 1200 p . . . . . . • T • 15 AUG 74 1200 p • lb AUG 74 1200 p . . • . T 1 AU 00 p • . . . 18 AUG 74 1200 p • . . T. p . . •
20 AUG 74 1200 p • . • . T • •
p . . . •
22 AUG 74 1200 p . . . • p •
24 Al!G 7ll 1200 • p . . • I . . •
• . . . . • . •
26 AUG 74 1200 p . . • T . • . . . . . . . . • ea ~t-o ;~ J.?DD , P. . . T
p . . . I . I • 30 AL'G 74 1200 p . . . . T. •
• . . • •
1 SEP 74 1200 p . . . T • . •
0 • . . . . •
3 SEP 74 1200 • p • . . T • p . . . . •
5 SEP 71.1 1200 • p . . . T
•
7 SEP 71.1 1200 p .
8 s E P 7 4 I 2·0 o p . ;x , ...... ~ I . • . •
9 SEP 74 1200 p
10 SEP 74 1200 . P. . "' . •
11 SEP 74 1200 . •
12 SEP 74 1200 . . • . . 1
13 SEP 74 1200 . p . . . • T
Ill SEP 7ll lt:OO • • • • F •
15 SEP 7ll 1200 . . • . . T . . ---p . • , ......
• . • . . . •
17 Sf.P 74 1200 . . . p . •
• . . • •
p . • . . • ., -.. -··-p . . . •
14 12QQ • p . . • -.. - -
•
74 1200 • p
74 1200 . . p
24 SEP 74 1200
25 SEP 74 1200
26 SEP 74 1200 . .. • T
27 SEP 74 1200 • p • T •
28 SEP 74 1200 p . T. • 29 SEP 7ll 1200 p -T
":i":\ f.;. c: C) 'l L1 \ ;;. 0 (l p
, lJ :E ..... m -G> ("') zO~o c m~~z
:0 >m.,(l) llllr-1 m -rz0-1 >moe , =Eoo:::!
(X) z:D.,o
• C>moz 1\) m:oo
I " ., ...
. ·---
., -G> c
]J m .,
(X)
•
1\)
I
1\)
FLO•~ CFS 10 AUG 56 1200 11 AUG 59 lt!OO 12 AUG :in 1200 13 AUG ':.13 1200 14 AUG :,a 1200 15 AUG 58 1200 16 AUG 58 UOO 17 AUG SB 1200 18 AUG 58 1200 19 AUG 58 1200 20 AUG ':)B 1200 FLOi'i CFS
8 SEP bl 1200
9 SEP b1 1200
10 SE.P bl 1200
11 SEP b1 1200
12 St.P b 1 1200
13 SE P 61 1200
14 SEP 61 1200
15 SEP 61 1200
1b SEP 61 1200
17 SEP t>1 1200
FLOW CFS
10 SEP bb 1200
11 SEP 66 1200
12 SEP bb 1200
13 St::P bb 1200
111 SEP bo 1200
15 SEP bo 1200
16 SE.P bb 1200
17 SEP ob 1200
18 SEP &b 1200
19 ::ii::P bb 1200
20 SI:.P bb 1200
21 S£P ob 1200
22 SEP &6 1200
2l SEP bb 1200
21.1 SEP bb 1200
25 SEP 1:>6 1200
cb St:P &b 1200
27 SEP &b 1200
28 SEP b& 1200
29 SEP bb 1200
30 SEP bb 1200
m
::0 ::0 > m
0 0>0
l-"0
m goZ -< (J)
::0 0> ....
-0> =i < 11C m ,_.
::0 0-
z o 0
m o 2
> (J) 0
::0 11 11
:I: 0 .....
0 ::0 co
3: 01 m ~e»
::0
o. bOO. o.o 1 0. 0 0 -----.....:. __ o. bOO. o.o 10.00
&-... ,.._ ----=.
o. bOO.
o.o 10.00 --
PLOT STATION NAMt CHARACTt::R C•FLO~ Af bKADLtY LA~l --CALCuLATED A-FLO~ AT bKADLlY LAKE --OBStKVEU 1200. !BOO, 2400. 3000. 3600. T 20.00 30,00 40.00 .._,.--...-50.00 --. --.e-.-----. .....-. . _c-/-,...cr""' • 0"' • PLOl STAilON NAMt:: CHAkAClE.K 60,00 . • r C-FLU~ AT ~RADLt::Y LAKE •• CALCULATED A•FLO~ AT tlRADLE.Y LAKE -· O~SERVED 1200. 1800. 2400, 3000. 3oOO. T 20.1)1) 30.00 40,00 50.00
----c---
. -c-"' • ..f:(' • • • T
• • T
PLOt STATION NAME
CHARACTtR
oO,OO
T •
C-FLO~ AT 6RAOLEY LAKt:: •• CALCULATED
A-FLUW AT BRADLEY LAKE •• OBSt::~vED
1200. 1800, 2400. 3000. 3600,
T
20.00 30.00
-=-c-.....-...... .
40,00 5fJ.OO
T
T
T
bO,OO
T •
T •
. . . ~ I A • • • . l!Jr-c .T '"i --:-c--:-y-o--:-• T • . _ ...... c--. . . T .
• • • 1 ~~--~·-• 1
1 •
• r
T T STAllON NUMBER CJNTROL 4200, •3bb5 70.00 10.0 Q 10,5 J 41\00, 4 100. 60.00 STAT ION NU"'~EH CJI.lTROL 4200. -.31>65 70.00 10.0 Q 10.5 Q 4800. 4 100, 80.00
STAT I Or~
NUMBER CONTROL
4200.
•3665
70.00
10.0 Q
10.5 Q
4800.
4 100.
80.00
5400. 6000. 90.00 100.00 51100. oOOO. 90,00 100.00
5400. 6000.
90.00 100.00
:J
~
;::,
0 .r.::
.........
II)
QJ .r.::
.. <..: c .....
I
.f-l ;::,
0.. c .......
QJ u .,
1+-
~
::l
Vl
>, .,
"'0 .........
II)
QJ .r.:: u c .,...
I c
0 ....
.f-l .,
~
0
0. .,
>
LLJ
SURFACE-SUBSURFACE SPLIT
1.51 I I I I I I J I I I I I I I I I I I I I I I l I I I I 1 1 1 1 :a 1 1 1 1 1 1
0.5 1.0 1.5 2.0
Surface & Subsurface Input-inches/hour
EVAPOTRANSPIRATIO~ INDEX
.ts~~~~~~~~~~~~~~~~~
I I I I I I I I ,NOn g 1 a C i a 1 ! I I I I
.10
.OS
0 1 [ ' II I I J I I I
J F MA M JJ AS 0 NO
I~ on th s
....,
c
QJ u
~
QJ
0.
1+-
1+-
0 c ;::,
0:::
1+-
1+-
0 c ;::,
0::: -~
0
I-
I+-
0
SOIL MOISTURE INDEX
50 I I I I ll'l
5
Soii Moisture Index-inches
BASE FLOW INFILTRATION INDEX
...., . I I I I '. I ! I ! I I ~ 50~ . 'I.' I I I: I I ' u '....j I I ; I :-1' i s.. ' ' QJ
0.
c ....
3:
0 ..-
1+-
QJ
II) .,
1:0
0 1-!
0 ..
"' 4
Baseflow Infilitration Index
6
+J c
CIJ u s..
CIJ
0.
c .... .,
QJ s.. ex:
"C
E
QJ
>
0 u
3:
0 c
Vl
SNOW COVER DEPLETION
so 100
Accumulated Runoff in Percent
MELT RATE INDEX
>? .10 ~ FFITltl'jl·~~~ff~
Ol
Q)
"'t~ .........
1.1)
(l)
..r::. g .OS
.,..
' (l)
.p
rd c::: .... ... -
(U
~ so 100
Accumulated Runoff in Percent
I
BASIN CHARACTERISTICS
FOR SSARR MODEL
'-----------------------------FIGURE F8.2-3-
BOARD OF CONSULTANTS
9.0 BOARD OF CONSULTANTS
9.1 INDEPENDENT BOARD OF CONSULTANTS
An independent Board of Consultants was formed to review the
engineering and design of the Bradley Lake Hydroelectric Project.
This independent board has met five times since being formed in 1983.
The reports of these meetings are included as part of Appendix B
Attachment 2 of this report. The board meetings, convened at either
the project site or in Anchorage, on the following dates:
Meeting 1 May 12 and 13, 1983
Meeting 2 July 11 to 15, 1983
Meeting 3 September 25 to 27, 1984
Meeting 4 November 4 and 5, 1985
Meeting 5 January 28, 1986
9.2 FERC BOARD OF CONSULTANTS
In February, 1986, the Federal Energy Regulatory Commission approved
the use of the Alaska Power Authority Board of Consultants to be the
FERC Board of Consultants.
The first meeting of the FERC Board was held in Anchorage on March 6,
1986. The FERC Board of Consultants report has been included in
Appendix B Attachment 3 of this report.
2-379-JJ 9-1
APPENDIX A
DRAWINGS
EXHIBIT F
I
I
I
I
I
I
I
I
I
I
·;..\
I' PROPOSED HOMER ELECTRIC
ASSOCIATION FRITZ CREEK-I SOLDOTNA TRANSMISSION LINE*
I
~
I
II
1
'[_
J
'(
/)
/
PERMANENT FACI LI;riES
~ ~f;" _ ... o-.... ........
.._o .. .._.,
/J
/ ~
BARGE DOCK Hr~
·,. .... , .........
-~ ~
lf<>rlh
~--. { \ ~t '(
~\.\ ~
\ I • "\ I
\ ;~-~-~..,.-·
\ ,. ""'-;---/ r----~· --···c.-.
\ ('---~,.. -,_ ' ·~ _"-~r,.,..
, . ...--
/ ,./··
/
_,/ / .. ."' -,__ ----.s'~ -.. __ .... _ --~"'~ . ...._ "--'"
'-. -~--------
..........
-:(~
-\__,..,
..-r-....___,~
-
STAGING AREA -I
L
\_
?
-\
\.
\ .__ -...____.-
(. --DIVERSION
*NOT INCLUDED IN SITE PREPARATION CONTRACT ,/
f ..
I
/
\f
/ ~ NUKA RIVER -'Y:f DIVERSION*.
~...4 0
-. ~"
'\\
, ..
; . ; \ . \
\
l,
','\.
' '
0
·.
·,,a; .....
.,-.... ..... -~ ............
.......
'• ' \
\
~
2 3
SCALE IN MILES
..... ,.
·-......... _
·· .. ,
·,' .. , ..
., ' ..... \.
\ OI .. GL E STADT '
\ GLAC II!:It ·-
\ ' , ... -..... ~ : \\ . .
\
\
l,
'!
'·.
\ .......
\
"' .............. ,
I
\ " .............
\ •.
\
'\ •.
' ' \ . \
...... ,.. c ' ·~ '·-"'--·--., '·-, n \ r--·· .._:............ ... ,..,~) \"\ \
~ ' ... -:.~;·::...., "..~ ........ .,.'
I \ ' \ ., .. ,..;,
; j... \ .. ~
• /I ., \
...... -...... ~ !I \.,-.._~'"' ..
... -...... __ t .. •, ......... • .... -...
-. __ ) 1 BRADLEY LAKE ~~DROELECTRIC PROJECT I
........ ~ ....
........ ~. · .... \
1 -,
'• ,t
' \ .
' '
ALASI<A IPOW &:R AUTtt O FUTY
GENERA L P L AN
PLATE 1
, .
~ ~
~ ~ 'b 0
NOTE:
UNDERWATER
TOPOGRAPHY NOT
SHOWN IN DOWNSTREAM
PCX>L AREA
CHANNEL IMPROVEMENTS
ON PLATE 13
BRADLEY LAKE
~
ROCK QUARRY
EL 1150
I
i'/
I I
I
I 'I ; L POWER CONDUIT SHOWN ON IJ/ PLATES 5 AND 6
~''!
I I
I I
~
0
0
"""
\1 c::::E LON
W.S.EL 1055'
--------
H+--1 GROUT CUR'TAJN
I
I
--------
--------
-------------------......._
---......._
CONCRETE
FACE SlAB
-----.......
ZONE 3A ZONE 3·B
PIT RUN QUARRY MATERIAL PIT RUN OUARR'f MATERIAL
ZONE 2 -SELECT COMA<ICTED ROCK (It 3' LIFTS
10 tt 5d = soo'
3 I 3 L _j
MAXIMUM DAM PROFILE
_rCONCRETE
.,( FACE SlABS
OVERSIZED
ROCK
//
MAX.W.S. DURING
DIVERSION [L 10a5.0} ~~J!R,o~
DUMPED !~PERVIOUS :;;> 5-'"
DUMPED
1.5
~1
UPSTREAM COFFERDAM PROFILE
"5 ® 12'
"6 x 6'-o· ® 6'
\_MAIN RE-BAR
"8 ~10' EW
FACE OF SlAB
f-------DOWNSTREAM COFFEROAIVI .I
9" NEOP. RUBBER
WATER STOP (TYP.)
.m
riJ < --' Vl
w
~
,u
riJ
:'i
Vl
~
(DUMPED IMPERVIOUS AND FILTER MATERLAL
REPLACED WITH RIP-RAP AFTER CONSTRUCTION)
•5 X 6'-Q' Iii ft
•5~12'
PR'EMCU>ED JONT
FILLER (TYP) ------
'
'o -.o
3-3
"9 HOOKED BARS-DRILL & GROUT
TOE SLAB
I TOE SlAB 'A' TOE SLAB •a• ~ =-:} TOE SlAB 'c' -, jj/ /
< ,-..._GROUT
-.........__ / CURTAIN
-..................____ /
-------------_......----
[li>.M
9' NECP R\.SBER
'l-ATER ST1)P (Typ)
TOE SLAB 11 A1 =41
TOE SLAB "B'= 6'
TOE SlAB 'C'• a'
·-.! P.V.C. GROUT
SLEEVE (TYP.)
•9 HOOKED BARS-DRILL & GROUT
3 E.<lCH FOR TOE SlABS 'B' & 'C'
2 ~o;~ctce: SLAB 'A'
~ f5-0' o.c.
VIEW LOOKING DOWNSTREAM
9' NEOP. RUBEER
WATER STOP (TYP.)
, -,
·o
-.:,
MAIN RE-BAR
•aiii10' E.W.
'*56l12'
MAIN RE-BAR
•aiOl'O' E.W.
"5 10l12'
2-2
'b -.:
4-4
THIS DRAWING SHOWS CIVIL CONSTRUCTON
CONTRACT WORK. THE MAIN DAM IS BEING
DESIGNED AND WILL BE A SUBJECT OF
THE CIVIL CONSTRUCTIOI~ CONTRACT
FINAL SUPPORTING DESIGN REPORT.
BRADLEY LAKE HYDROELECTRIC PROJECT
ALASKA POWER AUTHORITY
CONCRETE FACED ROCKFILL DAM
SECTIONS AND DETAILS
A ENOl=~~=~~ ~oe::o-r:noN PLATE 3
;OJr"'f I
RM3i N~10J978
RM 42 ~ 210J945
HM 43 N 2103817
OH 7 '14 2103750
DH JJ N 2103774
E 34 344a
E J4 3538
E 343465
E: 343584
PLAN
SCALE A
TOP OF
0VER8URD£N
, t:
119
s.o
95
, , I eo• EL 11950 ·1
\ I CREST EL 1180.0 }f----
1 I I I 1
EL.ii350
U/S CREST
~
Y<::0.99'
R1: 5.68'
R2; :. 72
=•"·rc
-~;--~:P:FFOUNDATION
GRADE ON ROCK
SECTION 1 -1
SCALE 8
\
""--GROUT CURTAIN
SECTION 3-3
y
I
' .
SECTION 5-5
SCALE B
X
5' IN TO SOUND ROCK
FLOW -f--.--------x
UPSTREAM
FACE
DETAIL A
NTS
DOWNSTREAM
FACE
PC 2
0 20
FLOW
SEE
~ONC. TRAINING WALL
/ -END OF UPPER SPILLWAY AREA
~
HOLE
SECTION 2 -2
SCALE B
r-SASE:LINE
. _/DETAIL A
CREST EL 11800 .?+: '\ .r-CLEANOUT
1155.0
)
GROUT CURTAIN/ SECTION 4-4
NTS
DIS CREST COORDINATES
X
0
1.00
2.00
3.00
4.00
5.00
5.00
7.00
8.00
9.00
10.00
11.00
12.00
13.00
14.00
;'CII5.07
P•;l 22.42
P 1 1 26.92
Pl1 34.13
PC2 35.41
P!2 42.92
P':'2 54.93
40FEET
0
0.07
0.24
0.52
0.88
1.33
t~86
2.47
3.16
3.93
4.78
5.70
6-69
7.76
8.90
10.19
19.37
2500
25.00
35.62
45.00
45.00
THIS DRAWING SHOWS CIVIL
CONSTRUCTION CONTRACT
WORK. THE SPILLWAY IS BEING
DESIGNED AND WILL BE A
SUBJECT OF THE CIVIL CONST-
RUCTION CONTRACT FINAL
SUPPORTING DESIGN REPORT.
BRADLEY LAKE
ALASKA
SPILLWAY
PLAN, ELEVATIONS & SECTIONS
SCALE B: !"; 2C'
0 40 80FEET
SCALE A 1": 40'
~<
8
' ~
-2
:::
uJ
~ :t
"o
-~
'o
~~
i
8
~
14'-u~
j2
'i I
r;3
1.3
INTAKE DETAIL
..:..u .. , .. ,
J4!-U
~TUNNEL
2-2
" ,.. .. e•• I
EA&..&., .. ,
--2!YJJ'
-2000
NORMAL TRANSIENT PRESSURE GRADIE_N __ T_,l,_ __ _
------------------------15001
C S7ATIC PRESSURE GRAOI ENT
--1000'
,t-END CF 2600' I . 8 I i 71 61 I STEEL LINER ====~~~~~~~~~~~~~~~~d ~ 7j ~ ~ ~ a.l~ ~ ~ ;J ~ ~ sJ § §
TORCIUE~ SOlE HOLE
FOR RAJSE ,,
'"
SEE EXHISfT F ·PLATE 6
FOR INTAKE GATE SHAFT
UPPER BEND DETAJL ...
JCA\..l•fUt
14-0
!
3-3
c.M.t .. nn
t TUNNEL
JS'·
4"4 ...
IC4lt•rU1'
~ ~ g :il 12 ii5 g ~ g g ~b 0
TUNNEL PROFILE
50CI o' sOCJ 1000' 1500'
SCALE; ,•. 5CX:l
7·7
=-.,.? .. ~."'.':,:::,,===.;;;:::J
CONCRETE
LINING
t TUNNEL & STEEL UNER
6-6 . . ..
~-22!!!5
f--END CF 2600' I l•14A50't • STEEL LINER
MAIN tUNNEL •t
S' -•
LOWER BEND DETAJ L ,.. .,..
CAU:•ntt
THIS DRAWING SHOWS CIVIL
CONSTRUCTION CONTRACT
WORK. THE INTAKE AND POWER
TUNNEL ARE BEING DESIGNED
AND WILL SUBJECTS OF THE
CIVIL CONSTRUCTION CONTRACT
FINAL SUPPORTING DESIGN
REPORT. <
STEEL
SET
&MANIFOLD
SLOPE teN
UNDER REVIEW
6'·8'
TUNNEL & STIEEL UIER
6'-8'
'1---t----+~-t--GROVT
s-s
~ 1
lleA!Ll.¥Uf
TUNNEL
HOLES
STEEL
SET
\--!---!1.--GRCIJT
8-8 . ..
JIII50P'""! 3
CM..~•naY
HOLES
HOOP &
LONGITUDINAL
STEEL
REINFORCING
BRADLEY LAKE HYDROELECTRIC PROJECT
ALASKA POWER AUTHORITY
POWER CONDUIT
PROFILE & DETAILS
PLATE 5
~00'
GATE SHAFT
e-EL 1203'
CONC COLLAR
2'-0'THICK
j .l I 22'" ti'> 1'-0"NOMINAL
' CONCRETE
LINING
1 - 1 ...
......._..nn
EXISTING GROUND L~ / _...------· ---//
~--//
..//~INTAKE & / __ / I TUNNEL
TRANSVERSE PROFILE . ,.. ..
~I
ICAI.llllfrllT
f_ COL
~·-I) I l:. ~uL ,----F { : q
~ :q. ..,.
~
.J:iln !: ~ 1 PuMP
.?:::I CONTROLS
SHAFT
PLAN EL 1203.0'
o' "'
ww;;; '
U.:ilU•fUT
SHAFT
3-3 . ,.. ..
l§l!lJiiOiiiO I
lltAU••nT
OIL ACCUMULATORS I
GAS BOTTLES
TUNNEL
PRESENT
LAKE LEVEL
EL 1080'
\7
INTAKE CHANNEL
SHAFT
HYDRAULIC
~~ ~ ~, .. ::::_-~s--
::£~=:-;-~-=--.::.;:.._-
2-2 ...
JC.At.J•nu
EXISTING /
GROUNDLY/
//
//
,,.''
_/
fEL 1115 •
-~/-fTEMPORARY \ ROCK PLUG
// I TOP EL 1090 '
/ \ \
I
LONGITUDINAL PROFILE ,..
IICAI.f IIJI$(tl
~
ACCESS
ROAD TO
GATE SHAFT ~
If GATE SHAFT
NOT YET
LOCATED
MAIN DAM~
PLOT PLAN-GATE SHAFT
w.-:223
1C:AlSNtUff
THIS DRAWING SHOWS CIVIL
CONSTRUCTION CONTRACT
WORK. THE POWER TUNNEL
INTAKE AND INTAKE GATE
SHAFT IS BEING DESIGNED
AND WILL BE A SUBJECT OF
THE CIVIL CONSTRUCTION CONTRACT
FINAL SUPPORTING DESIGN REPORT
BRADLEY LAKE HYDROELECTRIC PROJECT
ALASKA POWER AUTHORITY
INTAKE CHANNEL &
POWER TUNNEL GATE SHAFT
SECTIONS & DETAILS
PLATE 6
-,
-r.illQQQ
COOTROL NORTHING POINT
A N 2112610
B N 2112305.79
c N 2112590
D N 2112534.36
E N 2112474.36
F N 2112374.36
G N 2112669
H N 2112613.8
I N 2112604.4
J N 2112575.99
K N 2112537.39
L N 2112592.0
x6.2-------------x"6(;
0
0
"' "'
"'
I='UTURE POWERHOUSE LOCATION
EXCAVATE TO EL 390"
------l ~ 327000
EASTING POINT DESCRIPTION ~g;r,\'? NORTHING EASTING
E 327240 POWER TUNNEL WORK POINT (FUTURE J M N2112700 E 32n65 25
E 327381.86 POWER TUNNEL P.C (FUTURE! N N 2112555.85 E 327265 25
E 327115 PH COLUMN LINE INTERSECTION-WORK POINT 0 N 2112437.34 E 327265 2 5
E 32 7194 PENSTOCK* 1/COLUMN LINE P.l (FUTURE J p N 2112355.27 E 3 27265.25
E 327194 PENSTOCK#" 2/COLUMN LINE Pl. (FUTURE} R N 2112226 E 32726525
E 327194 PENSTOCK#3/COLUMN LINE PI ( FUTUREl s N 2112150 E 327246.05
E 327218 SUBSTATION EL39/EL18 CUT SLOPE PI T N 2112700 E 327236
E 327248.16 TUNNEL PORTAL EL 60~/EL 39 CUT SLOPE P.l. N2112150 E 327193.65
E 327228 TUNNEL PORTAL EL60t/EL39CUT SLOPE P.l v N 2112700 E 327195 67
E 327228 ACCESS ROAD EL 60 i: I EL 39CUT SLOPE P.l w N 2112509.4 8 E 327286.8 8
E 327246 ACCESS ROAD EL 60 tIEL 39CUi SLOPE Pl. X N 2112440.91 E 327318.85
E 327196 SUBSTATION EL 391EL 18 CUT SLOPE P.l. y N 2112326.63 E 327312.14
ROCK DOWELS AND ROCK
BOLTS 3TART AT N 2112220
AND CONTINUE TON 2112700
REF PLATES
\_CONSTRUCTION
STAGING AREA
EXCAVATE TO
EL39.a\
\
POINT DESCRIPTION
x6.o
MATCH POINT ON TANGENT-ACCESS ROAD i
POINTONACCESS ROAD(. & It_ POWER TUNNEL
HIGH POINT ON TANGENT-ACCESS ROAD ([ "s.6
POINT ON ACCESS ROAD ot & ot PENSTOCK # 3
PC. ON LANDING STRIP ACCESS ROAD ot
MATCH POINT ON CURVE-ACCESS ROAD <t.
MATCH POINT ON TANGENT· PH ACCESS ROAD cr.-
MATCH POINT ON CURVE-PH ACCESS ROAD (f"
MATC!-1 POINT ON TANGENT-SUBSTATION ROAD~
P:.ENSTOCK f:f-11 POWER TUNNEL P.l. (FUTURE)
PENSTOCK-*" 21 POWER TUNNEL P.l (FUTURE)
PENSTOCK#31POWER TUNNEL P.l. (FUTURE)
NOTE: EXCAVATE TC TOE
OF ROAD SLOPE
l.
4
0 20 40FEET
I jjjjl
SCALE: t•:: 20'
A
THIS PLATE SHOWS SITE
PREPARATION CONTRACT
~
WORK. FUTURE EXCAVATION
FOR THE POWERHOUSE AND
PENSTOCK WILL BE PART OF
CIVIL CONSTRUCTION CONTRACT
FINAL SUPPORTING DESIGN REPORT,
BRADLEY LAKE HYDROELECTRIC PROJECT
ALASKA POWER AUTHORITY
SITE PREPARATION EXCAVATION
AT POWERHOUSE
PLAN
PLATE 7
80
60
..
~
FUTURE POWERHOUSE EXCAVATION
F'!LL & RIPRAP DETAIL
1 • ,
SECTION £327156
~ A
7)
GA9!0NS-OET 0 {H~9;
0
~I
~
~
TO EL
2-2
SECTION @ N2112650
SCALE A
(PLATE 7)
I FUTURE POWERHOUSE 1 L~:·~
3·3
SECTION@ N2112470
SCALE A
(PLATE 7)
4·4
SECTION @I N2112225
SCALE A
(PLATE 7)
EXCAVATE TO EL 39.0'
GAStON: TYP GAS ION:
INSTALL.ATICN ITERMINATlON OETAIL"'
---j r--1.5' ( TYP)
,r-r,--.._,.._,~..,:..l-1----,ST AGGER
I !! I II I I
ELIMINATE BOTTO~ i \i!Y..i'ti&.:a\1 M;;t....,"t
ROW WHEN SLOPE
HEIGHT IS LESS
THAN 15'
DE TAIL A
TYPICAL ROCK SUPPORT
ASOVE LANDING STRIP ACCESS ROAD
NTS
f* TO ROCK DOWELS 10
LONG
# 6 GRADE 60
THREAOBAR ROCK
DOWE'lS 10' LONG·
DET E
# 10 ROCK
_DOWEL (TYPl
# 9 R'OCi<
DOWEL(TYP)
•a ROCK BOLTS
~ 5.0'0C EW
STAGGERED
FACE
REOD ONLY r HE X NUT ------., !~~{~~lNG~ i~::h~:ILly~ 2)
DETAIL B
TYPICAL ROCK S.UPPORT
ABOVE EL 39.0' BENCH
NTS
ROCK
L~OLE
GROUT OR SLOW
RESIN FOR FULl
-~--
ENCAPSULATION I
THREAOBAR ,. 8 GRADE 60~ f.=
~ 2''
'* 6 ROCK SOL TS _fTfYPl
~ .. "G~E'i.~DEW f
DETAIL E
NTS
5.o· I (fYP) EL 39.0'
.;.10 ROCK OOWEL(TYP)
TYPICAL ROCK SUPPORT
ABOVE: E L 180' BENCH
SCALE B
LANDING STRIP ACCESS
ROAD-DETAIL D
ELVARIES. (ROAO CUTl
CHAIN Llt-'K MESH-OETAfL E
39.0
DETAIL C
TYPICAL SENCH SUPPORTS
SCALE B
EXCAVATE TO STABLE
CUT FOR CONSTRUCTIONJ11"""' {1H"1VOR FLATTER IN .~
~~~~8~~~~~NU,~I'\ 10V lN
BACKFILL W/E:XCAVATED
RANOOM FILL TO TOP
OF GAB IONS (MAX 2.0'
LIF'T HEIGHT)
GEOTEXTILE (TO 1.0'
BELOW TOP OF ROCK,
TYPE At)
UP TO 6" BEDDING OF
GRAVEL FILL OR fi!OCK
$PALLS ALLOWABLE'. TO
SMOOTH PLACEMENT
SURFACE
DE TAIL D
TYP GA810N PLACE ME NT
SCALE 8
(PLATE 7 )
PLACED WITH LONG AXIS
PARALLEL TO WALL TOP
ROW ONLY
iOP OF EXISTING BEDROCK
(SEE SLOPE NOTE, PLATE 71
0 10 20FEET
I ;a
SCALE B: t•:tO'
0 20 40 FEET
I i2
SCALE A: t":20'
DOWEL
THIS PLATE SHOWS SITE PREPARATION
CONTRACT WORK. FUTURE EXCAVATION
FOR THE POWERHOUSE AND PENSTOCK
WILL BE PART OF CIVIL CONSTRUCTION
CONTRACT FINAL SUPPORTING
DESIGN REPORT.
.A
BRADLEY LAKE HYDROELECTRIC PROJECT
ALASKA POWER AUTHORITY
SITE PREPARATION EXCAVATION
AT POWERHOUSE
ELEVATIONS
PLATE 8
6C6•j>STL PENSTOO<
6'-6" DIA PENSTOCK
IN TRENCH
11 1 9 SlL
LINER--
NTS
i i_ PENSTOCK
DRAIN {TYP)
11' DIA. PENSTOCK
0 10 20FEEf
r 1 •• TERSE:CTlON
f_ PENSTOC<IENCASED
GRAVEL SI..AfAU:.
i:.L 4Q'±
~
I'TERSE:CT!ON .NNEL I ' INTERSS::TION I ' IN CONCRETE
r f--__ -·):;·---·""' .. . u .,.1 -"" -------::-. ..._ ---=-=---~-. ' •. . : OJT !.CQ'{ER SECTION hj ffir ·r-'"J""' --· ' ,, -, ' ' ± --l ···---· -, '---, -"< .,_--' '----~---j . :+ = = = ::.-_ =-:· _-><::.'~C:: o:.~::------___-.,_ ~ '_;____ -::::::::----::_-:-_:_-_ -:_-_ :_.---I : ----------_;_~·-----·
PENSTOCK ORA IN (TYP)
(OETAn.S LATER)
PENSTOCK & POWERHOUSE
0 10 2Cl FEET
~"f,UtllTS
EL40'
E L .""'iNUS 9':L
FUTURE UN! T EXCAVATION
\ ~LD~~:;~~rs
,..J-o•
·.·-1, ·. • .. -4ll ~
24'-0"
GATE
EL MINUS9'±
THIS DRAWING SHOWS CIVIL CONSTRUCTION
CONTRACT WORK. THE POWERHOUSE
AND PENSTOCK ARE BEING DESIGNED
AND WILL BE SUBJECTS OF THE CIVIL
CONSTRUCTION CONTRACT FINAL
SUPPORTING DESIGN REPORT.
A
BRADLEY LAKE HYDROELECTRIC PROJECT
ALASKA POWER AUTHORITY
90 MW PEL TON POWERHOUSE
STONE I. VWEBSTER
ENGIN£ER1NG COf:tPORATIOIII PLATE 9
I
\
I
I
' '
\7
\7
PROBABLE MAXIMUM FLOOD LEVEL EL 1190.6'
NORMAL MAXIMUM OPERATING RESERVOIR LEVEL EL 1180.0'
ROCKFALL BENCH
EL 1120.0'
EXISTING GROUND
LINE (APPROX)
GATE HOUSE
GAlE SHAFT
EXISTING G~OUND
LINE ( APPROX)
ROCKFALL B~NCH
E L 1 120.0'
TEMPORARY ROCK
PLUG /
/
,..,..---
//'
I
GROUT RINGS____!
/
/
/
/
//EL10965' I
' ' ' ' ' EL 1062.5
I I ---
1 \<{ cEL1076Q' SLP:1 0•1. ~~~~~~T~?NNE FLOW EL 10600'
I
GROUT CURTAIN~ I 11-~~--------------~-----------=---~~~--:,:H~A~~---
o 10 en 0 1(1 BY PASS
~~ :!'?~~ ;!~~"!
..,~ Vl~Vlt"'l V'Jt"'l V'Jt"'l
"' ;!r:
"''"'
SITE
PREPARATION CIVIL CONSTRUCTION
CONTRACT f CONTRACT
EL 1076 0' CON CRETE I CONCRETE
i2
DIVERSION TUNNEL SECTION
SCALE B
"' ~c;
"'0
~0
00
++ 00
;!;!
"'"' -'-' ww
H
<(
~I
u ..
~
5j
(};)
'-0 -----FLOW -T-ri:J.;NEL ]0
~~====~~~~.u ~2 ~
5.J SITE PREPARATION CONTRACT v.oRK ON THIS DRAWING
INCLUDES:
EL10760'
'ro Jil TUNNEL
>s
1-1
SCALE A
r
2-2
SCALE A
EL10890'
EXCAVATION
I ~ SPR!~GL~N~
"!
"'
•'
PLAN OF TUNNEL
SCALE B
<t. SHAFT
I PENSTOCK AIR
VENT PIPE
10'-6"
3-3
SCALE A
4-4
SCALE A
11:.
I
I 40'-0"
'.coNe I wALL"\
• EXCAVATION OF DIVERSION TUNNEL
• CCNSTRUCTION OF INTAKE OF DIVERSION
THIS DESIGN WORK IS PRESENTED IN THE SITE ~TON
CONTRACT FINAL SUPPORTING DESIGN REPORT.
CIVIL CONSTRUCTION CONTRACT WORK INCLUDES:
•EXCAVATION & CONSTRUCTION OF GATE SHAFT
•LINING OF TUNNEL DOWNSTREAM OF INTAKE
• CONSTRUCTION OF DISCHARGE STRUCTURE
THIS DESIGN WORK WILL BE SUBJECTS OF THE CIVIL
CONSTRUCTION CONTRACT FINAL SUPPORTING DESIGN
REPORT.
BRADLEY LAKE HYDROELECTRIC PROJECT
ALASKA POWER AUTHORITY
=TOC~ • G Htltl1 G • r .SL~
.&
CONSTRUCTION DIVERSION
SECTIONS AND DETAILS
STONE & VI'EBSTEA
ENGINEERING CORPORATION
PLATE 10
E L 1063.0'
0 20 40 FEET
I ......
SCALE B: 1 ·, 20'
0 8 16 FEET
I iiiliiil 5-5
SCALE A
SCALE A: 1":8'-0"
~
aoYELOPED PROFILE
TYPlCAL SECTION
-.. ,...., -:s
~CAU•nu
CONDillONS IN CONDUIT
DISCHARGE = 350 CFS
CORRESPONDING DEPTH =4.13 FT
VELDOTY = 16.9 FT/SEC.
STATE-SUPERCRITICAL
THIS DRAWING SHOWS CIVIL CONSTRUCTION
CONTRACT WORK.
THE MIDDLE FORK DIVERSION
WILL BE A SUBJECT OF THE CIVIL
CONSTRUCTION CONTRACT FINAL
SUPPORTING DESIGN REPORT.
BRADLEY LAKE HYDROELECTRIC PROJECT
ALASKA POWER AUTHORITY
MIDDLE FORK DIVERSION
PLAN & PROFILE
PLATE 11
~ .------------------------------------------------------------------------------------------------------------------------------------------------.
SPILLWAY CHANNEL
SALLWAY WIER
CONCRETE APRON
DOWNSTREAM OF
LON LEVEL OUTLET
PLAN-MIDDLE F~K DIVERSION
INTAKE
CENTER LINE
NATURAL FUO'W
~
DETAIL A
41
MAX. HW. EL. 2210'
?:!x 7:! SLUICE
WITH CIRCULAR
WALL Tl-IIMBLE-----
I r--;,71'----'1 \z I 1---
--.... T ---~LEVEL --J I l', ,. • "~ , -""' I I ' ,/i• "·"
04
' l
, ill r-, ~~LION"-. )-CONCRETE ROCK LINE ---' I \ -· . I ·~ .. ' 'I .. . I ' -,
TOP OFD<W
EL.2212'
---L I ---
· · -~ <~/ Jt,J ---r~ .. r--T:n·--·-r-·-~T .. ('J<l----~lr 1 TJ·:---, ,--J
1j_L _j )..-.I..-_L_i _ _l_ Ll 1----' ~ru~•' -l--t-_l_L__> -/ -~c ~ w•rn ~m ® SHEET ALE INTO ROCK
CUT-OFF WALL
VI'EW LOOKING DOWNSTREAM
MA~2210'
15
9
' rCOMPACTEDJ
•a .l ROCK FILL
,;"-(TYP)
1-1
M"
2;:.2
GROUT CURTAIN~
3-3
~I ~. MAX. H.W. EL.2210'
EL.2200'
LOW LEVEL
OUTLET
31
VIEW LOOKING DONNSTREAM
AT SHEET PILE CUT-OFF WALL ...
PZ 38 CAULKED INTERLOCKS
SHEET PILE CUT-oFF WALL
GROUT CURTAIN
~D<W 4-4
EL.2204"
EL.2200'
DETAIL B
DETAIL A
SELECT BEDDING
MATERIAL BELO'W
PIPE SPRING LINE
CONC. APRON
(30"x15)
Wz ~:3 ~a.
zw ww OlVJ
THIS DRAWING SHOWS CIVIL CONSTRUCTION
CONTRACT WORK. THE MIDDLE FORK
DIVERSION WILL BE A SUBJECT OF THE
CIVIL CONSTRUCTION CONTRACT
FINAL SUPPORTING DE SIGN REPORT.
BRADLEY LAKE HYDROELECTRIC PROJECT
ALASKA POWER AUTHORITY
MIDDLE FORK DIVERSION
ELEVATIONS & DETAILS
PLATE 12
--
1090
1050
........... ~.... _, . b":"' ,.,..-/ ----......
,;.Oo .,....... ,.,..-,
-// .?'d," ,...---J
,.... / /">"' / L"'t
(
/ -~ / / !? Ji' /
.---/ I ..p 0"" /
1L----/' //... ~d'
/(t. "'/ / "' ( \...' ..... / I ;.. liMfT OF "'
\ 1 I //' 1 ~ EXCAVATIO~
\ /1 I \ I I
I f 1 \ \ ';; I 1
11 ,_ \ ~ / f ,, --', ', y,/ /
-' ' -J ,,---,"". ',
' \ \ ' \ \ \ -
\ \I
'/--/-:.-.... -~,00:-
,, /
/
I /
I / I
I I
I I
r-·4f'P'IOX EXIST ·!'lATER
APPROX TOP OF' ROCK
EXCAVATE TOE/POSE
ELEVATION OF RIPRAP
TOP 01' BEDROCK FROM ro EL lOBO
WASTE FILL DISPOSAL
AREA B. FlLL TO
£:...1100 MAX
PLAN
DIVERSION CHANNEL
APPROX TOP OF COMMON MATERIAL-EX!ST
... , .... ,
'~ "',, ... ', '·,
DISPOSAL '.,, WASTE :.'~tl.~ TO \
MAX \ (};)
/
10801 ~ t
~.
1070
1060
i050J
L
1-1
t:XTE:NO TO ~~~~~~~~~mq~~~==~~==========~~~~~~~~::~~~illi~~~;;::~~~:::;~~~~~~~~~·~~------_:E;;XCAVATION APPROX STA 14!+4 4
---+ SLOPE ~ 0 33"f.c :::-+SlOPE z :lo •r ..
THIS DRAWING SHOWS SITE
PREPARATION CONTRACT
WORK.
'-
~
1h00 tz.oo
BRADLEY LAKE
ALASKA
DIVERSION CHANNEL PROFILE MAIN DAM DIVERSION
CHANNEL IMPROVEMENTS
0 40 80FEET
I -SCALE:: l"~ 40'
•,
~"'"'""
---'~----r-~ ~· :112100 ~~~~:t '\ .. ~-:----~~ ·~----~ ~, ~.
30-----
/'
40
60-
-t;; 211'!600
... r;:
8
BAY\
---1; 2112600
...
"' "' ....
8
~2112100
...
"' "' 8
SHGP/WAREHOUSE
~
_/~ ~/// ~2111600 70
~
"' 8
FUTURE
/
TAILR..1.CE
(CIVIL
CONSTRUCT ION
CONTRACT)
~g~,'i,RREHOU sE-=:1
{CIVIL
CONSTRUCT tO
CONTRACT)
0 50 100 FEET =
SCALE; 1•: 50'
-t~ 2111600
I~
0
0
70
ELB
THIS DRAWING SHOWS SITE PREPARATION
CONTRACT WORK,
~
BRADLEY LAKE HYDROELECTRIC PROJECT
ALASKA POWER AUTHORITY
GENERAL ARRANGEMENT
PERMANENT CAMP
& POWERHOUSE
PLATE 14
/? J x-7. 6
~~.o
x-7. 7
x-7. 4
0
OPTIONAL
DQCI"i EXTENSION
MAY BE INSTALLED
BY CONTRACTOR
x-7.4
y; ~~EE0c"~LE -----;:::·" _...---/." ... ' . ·~·~'"
~,,.---.• ··Y ·~·"------/ '":'~""'~~ /~ +~ N2112000 / J .... . "
/~--~ X -2.4
Jl(-2.8
---~---
x-2.6
j ~~·20-------------x-1.6 Jl( -1.7
X -1.5
x-1.5
·2.0
HORZ./VERT. CONTROL MONUMENT
SHEEP POINT
N 2111279.99
E :ffiT65:9'1
ELEV .• 14.48 I PROJ. DATUM
x-1.5
X -1.5
x-.9
X•2.9
G~AOE THIS AREA AS REQUIRED TO PROviDE
-RM 130 GRACING OF SILT~ SHALL BE BY CUT ONLY.
(
UNIFORM BOTTOM FOR BARGE GROUNDING.
MINOR FILLING TO OBTAIN GRADE SHALL
UTILIZE MARTIN RIVER BORROW. UNIFORM
GRADE TO EXTEND 100' BEYOND FACE OF
CELLS ON BOTH SIDES OF CELLULAR
x -2.7 / BULKHEAD.
_;;
x-2.2
I
x-.9
Jl(-.4
x-.2
X -.6
x. 3
xl.O
NOTE: END CHANNEL EXCAVATION AT ·6.0' CONTOUR lt!.LAT"IONSHtP 01 V[RTtCAL OATUNS
APPROXIMATE STA. 9+60
x-2.2 (
x-2.3
j ...
x-1.1
x-.9
x-.7
(9 RM 134
0
/ __r _ __/x.2
r
~cii~~E~T~~~t!c[~~s tt.
ROAD STA. !156+62.02 •
BARGE ACCESS STA. B 0•00
N 2111339.43
E 321616.63
xt.O
0 ~OFEEf
SCALE: 1•; 50'
0
0
2
X 2.1
x-1. 2
K.UCOVl
WI.I.W .. ,...
.. " ... ......
11.60
N8N SLOUGH CHANNEL
EXCAVATE TO EL -6 0
llA• COWl ...
O&Tu•
~::
-ooo
-911
ll:l'IOo..F.Y
I'IIOJEo.T
OATUII
.,,
'"
PfiOJf.CT" OATUM
ORIGIN (ASSUME(
N
ALL DREDGE MATERIAL REMOVED FROM SLOUGH
CHANNEL SHALL SE STOCKPILED IN WATERFOWL
NESTING AREA
X .1
x.4
x.9 x.9
X 1.2
-......________
5 ....____,
~ ~ L CHANNEL EXCAVATION INTERSECTION
AT EXISTING CHANNEL STA 0• 30
(N2,111,.773* E322,183'*)
CONTRACTOR TO FIELD LOCATE
NOTE: A.LL ELEVATIONS ON THIS DRAWING
ARE PROJECT DATUM.
l""" THIS DRAWING SHOWS
SITE PREPARATION
CONTRACT WORK
J,i,
BRADLEY LAKE HYDROELECTRIC PROJECT
ALASKA POWER AUTHORITY
BARGE
STONE & WEBSTER
ENGINEERING CORPORATION
DOCK
PLATE15
~
NOTE·
REF PLATE;: 7
SEE MATCH 5HT
551095-AR ·4
~
f327000
PLOT PLAN-POWERHOUSE SUBSTATION ...
-u: .. nn
GRACING lN PORTION OF
SUBSTATION WILL BE PART
OF CIVIL CONSTRUCTION
CONTRACT
~
POWERHOUSE
0
5I
~
327000
TO SOLDOTNA
TO FRITZ CREEK
PLOT PLAN -BPADLEY JUNCTION
. . ... ....
~zc:::s
--·WO,)D POLE
STRUCTURE
TYPICAL TRANSMISSION STRUCTURE
~IM/'fiT
g
TO BRADLEY
LAKE PROJECT
THIS DRAWING SHOWS CIVIL CONSTRUCTION
AND TRANSMISSION CONTRACTS WORK.
THIS WORK WILL BE INCLUDED IN THE
CIVIL CONSTRUCTION FINAL SUPPORT!N
DESIGN REPORT
A
BRADLEY LAKE HYDROELECTRIC PROJECT
ALASKA POWER AUTHORITY
POWERHOUSE SUBSTATION AND
BRADLEY JUNCTION
PLATE 16
------------------------------------------------------------------------------------------------------------------~
I -
115KV LINES
TO 8RAOLEY JUNCTION
SA
r-"~" • ov> v•uo·• E OYUE\-0 ~0$21 0YUB-PCB2 C: 0YUB-MOS22
MGS21 f-® OYUEI--! MGS22 r 0YUEI-
OYU~1 ~ MGS~
1
.,_Y 115KV BUS OYUS·JB B 115KV SUS OYUB·4B •
Z~~~a@ t ~21~~1 ~tV~-~bus~2
lGMS-XV1
1YUE\-~i: WUB· MGS1T E MOSIT rOYUB-j® 0YUS-MGSJ1 MGSJ2 ,,
,. 1MTX-XM1
MN XFMRl
33.8145.1 156 :JMVA,,'.l8-TT5KV
)PH,60HZ,l::-9•t,.
9' 1NPS-AC810 9"' 2NPS-AC820
120QA. 1200A
OEGS·G, ~DIESEL GEN
lk KVA, 480\1,
,. -~ ONJS·X$1 l ~O<X:V133JK'¥1 l10Q0.113331<VA 3PH.60HZ
9 STA SERVT 1JS00~480V 1J800·480V
'GMS-AC81 XF"MR1 JPH, 60HZ :) OEGS~ACS 301 T JPH,60HZ
GEN BRKR NO. 1 f:--"<
3000A _ _ )oNJS-ACa•m ,) ONJS·ACB10J I) ONJS-ACa2o1
ONJS·VS2 _j_
' 480V 00$
1GMB-XV2
1GMS-G1
GEN NO 1
13.8KV, JPHJ>OHl
5.9MVA , 0. 95 Pf:
'"~~.(n
NEUTXFMR ru
9. 2GMB-XV1
2GMS-ACB1
(;F.N BRKR NO.2
JOOOA
-.c:=r
vr
6 !<HIJJ---3 8>-VT
2GM8-XV2
TO DIAMOND RIDGE ~T~~-
":[ "'r
LINE 2
TO 6RAOI..EY LAI(-E /
BRADLEY JUNCTION
;r,2NPS-ACB40 ;r, 1NPS-I>CB30 Y. 1200A Y. 1200A
T l 0NPS-XA1
~PROJ.::CT f:"ACIUTIES
SERViCE: XFMR NO 1
.ttf I~VA.138-l2_47KV
JPH,&OHZ
F'EEDER TO
PERMANENT
PROJECT f"ACILITIE:S
BRADLEY LAKE HYDROELECTRIC PROJEC7
ALASKA POWER AUTHORITY
&
MAIN ONE LINE DIAGRAM
STONE l 'hEBSTER
ENGINEERI._.G CORPORA TlON PLATE 17
MARTIN RIVER BORROW AREA
0 200' <100'
~I
CAU! .. f'Uf
)' 06]
TYPICAL MARTIN RIVER
OORRON AREA DIKE
o s' HI' 1'5iiew-I
ICAUWII'IU
BRADLEY LAKE HYDROELECTRIC PROJECT
ALASKA POWER AUTHORITY
PROPOSED MARTIN RIVER BORROW AREA
PLATE 18
......_____ 20 .
y<·77) <::~'if.: -~~/ '-.£.. ::;/
------{-15)
;;;
~~--,7~ 1;----·200
_..r-
?ERM"-NEN11 CAMP SITE~
PLATE 14
LOWER
CONCRETE
SATCH PLANT
SlTE ...._____,
SPOIL DISPOSAL !!. WATERFOWL NESTING AREA
CONCRETE DROP BOX
TYPICAL ROAD SECTION ALONG
12 .. B£DOJNG BLANKET
EA SIDE
DREDGE DISPOSAL!!. WATERFOWL NESTING AREA
0 1()' 20'
MtU ~
SCALE lN Ft;;ET
0 200 400
~I
SCALE IN FEET
WATERFOWL NESTING ISLAND SCHEDULE
TOP
TYPE NUMBER WIDTH
REO'D. '?.l'::'
1 64 1'-5'
2 64 5'-10'
~---64 10'-20'
4 40 5'-10'
--
TOP
LENGTH
DIM.
r -5'
5'-10'
10'-20'
20'-100'
REMARKS
SMALL
MEDIUM -----LARGE ·--
PENINSULA
15' • 2.0' RECLAIMED
DREDGE
SEED TOP AND UPPER SLOPES
FROM EL 10' TO EL 12'
_.....,.:sz_ __ MA." ··-~. -• . ·~
....& ...
THE WATERFOWL NESTING AREA WILL
BE INCLUDED IN THE CIVIL CONSTRUCTION
CONTRACT WORK AND WILL BE A SUBJECT
OF THE CIVIL CONSTRUCTION C.ONTRACT
FINAL SUPPORTING DESIGN REPORT.
a
BRADLEY LAKE HYDROELECTRIC PROJECT
ALASKA POWER AUTHORITY
WATERFOWL NESTING AREA
;:) I 1,/NJ: • 'hEBSll:!R
EHGINE.I'£R1"+G CORPORATION PLATE 19
FIGURES
.l
CALCULATED FOR MODIFIED ACCELEROGRAM
NORMALIZED TO 0.75g -5% DAMPING
KERN COUNTY EARTHQUAKE 7-21-52 FRIULI, ITALY EARTHQUAKE 9-15-76
TAFT LINCOLN SCHOOL TUNNEL (S69E) SAN ROCCO (EW)
SCALE FACTOR = 3.50 SCALE FACTOR = 3.18
2.25r-----------------------------------------------------------------------------------------------~
-0) -z
0
1.88
t-1.50
< a:
LU
....J
LU
(.)
(.)
<
....J
< a:
1.13
t-(.) 0.75
LU a. en
0.38
~RESPONSE SPECTRUM
~ FOR MODIFIED ACCELEROGRAM
BRADLEY LAKE HYDROELECTRIC PROJECT
MEAN RESPONSE SPECTRUM FOR MAXIMUM EARTHQUAKE
(NEARBY SHALLOW CRUSTAL FAULT)
DAMPLING RATIO = 0.05
REFERENCE:
WOODWARD-CLYDE CONSULTANTS
REPORT: "DESIGN EARTHQUAKE STUDY"
NOVEMBER 10, 1981
o.oo~----~------_.-------L------~------~------~----~------~-------L------~------~----~
0.00 0.25 0.50 0. 7 5 1.00 1.25 1.50 1. 7 5 2.00 2.25 2.50 2.75
PERIOD (sec)
3.00
MEAN HORIZONTAL
RESPONSE SPECTRUM
----------------------------FIGURE F6.2-5-----
' I
I ,....
0) .._,
z
0 -r-
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MODIFIED ACCELEROGRAM OBTAINED FROM THE FOLLOWING TWO ACCELEROGRAMS
KERN COUNTY EARTHQUAKE 7-21-52 FRIULI, ITALY EARTHQUAKE 9-15-76
IIA004 TAFT LINCOLN SCHOOL TUNNEL, COMP S69E AND 1-3-169 ITALY SAN ROCCO, COMP EW
SCALE FACTOR ::: 3.50 SCALE FACTOR ::: 3.18
0.75r---------------------------------------------------------------------------~
0.50
0.25
0.00
0.00 SEC TO 2.32 SEC OF MODIFIED = 0.00 SEC TO 2.32 SEC OF KERN CO.
2.34 SEC TO 4.30 SEC OF MODIFIED = 2.14 SEC TO 4.10 SEC OF FRIULI
4.32 SEC TO 55.14 SEC OF MODIFIED = 3.58 SEC TO 54.40 SEC OF KERN CO.
THIS PLOT LIMITED TO FIRST 48.0 SECONDS OF THE MODIFIED ACCELEROGRAM
:::l-0.25 0 a:
c:J
-0.50
-0.75~----~~------~~----~------~~----~L-------~----------~--------~--------~-------L---------L------~
0.00 4.00 8.00 12.00 16.00 20.00 24.00 28.00 32.00 36.00 40.00 44.00 48.00
TIME (sec)
DESIGN ACCELEROGRAM
L__---------------~----------FIGURE F6.2-6-
APPENDIX B
CONSTRUCTION SCHEDULE CONTRACT DATES
APPENDIX B
FINAL SUPPORTING DESIGN REPORT
SITE PREPARATION CONTRACT
VOLUME 1
ATTACHMENT 1
CONSTRUCTION SCHEDULE CONTRACT DATES
SITE PREPARATION CONTRACT
Bid Advertisement
Bid opening
Contract award
Construction start
CIVIL CONSTRUCTION CONTRACT
Bid Advertisement
Bid opening
Contract award
Construction start
TRANSMISSION CONSTRUCTION CONTRACT
Bid Advertisement
Bid opening
Contract award
Construction start
March 10, 1986
April 15, 1986
May 1, 1986
June 1, 1986
February 1, 1987
March 15, 1987
June 1, 1987
July 1, 1987
August 1, 1987
November 15, 1987
December 1, 1987
January 1, 1988
The Final Supporting Design Report including final drawings for the
Civil and Transmission Construction Contract will be submitted to the
Commission for their approval in January 1987.
2-383-JJ
INDEPENDENT BOARD
OF CONSULTANT'S MEETINGS:
. ' ;.,
)
)
MAY 17, 1983
Bradley Lake Project
Dear Sir:
We visited the site of Bradley Lake Project on May 12. Discussions were
held with you and your staff on May 12 and 13. The present task is to
evaluate the feasibility of the project. The following summary is our
conclusions and recommendations.
1. We consider the geologic conditions favorable. There do not appear
to be any physical conditions which would preclude development or
result in excessive unanticipated costs from the estimates now
being developed.
2. \~e concur· completely with the basic layout now being considered.
We consider the revised intake design and location, spillway,
powerhouse location, and method of diversion significant
improvements.
3. We believe an embankment dam approximately at the axis nov con-
sidered to be feasible and appropriate. We consider a concrete
faced rockfill dam satisfactory. A rockfill with till core could
also be considered. We note, however, such a design is subject to
more delays in construction from ~.;eather and requires a larger
total volume of fill and wider base width than a concrete faced
dam. Thus space limitations, considering the location of the
intake, cofferdam and topography of the right abutment, might
result in significant problems in layout and greater costs for the
rockfill dam with impervious core.
4. Studies on other projects have shown repeatedly significantly
larger costs for concrete gravity dam as compared with an embank-
ment dam where both are located along the same axis. At this site
an alternative axis located upstream would offer abutments and
crest length height ratio favorable to the use of a gravity arch
with probably some saving as compared with a gravity dam at the
present axis. We are not at all certain that space limitations
would make this feasible considering topography, requirements of
the cofferdam and intake to the power tunnel. We believe fea-
sibility of this concept could be evaluated from a preliminary
layout and suggest this be considered.
·. ·• . ..
)
5. Examination of the rock indicates a quarry can be developed which
will produce excellent rock for a rockfill dam ~ith minimal zoning
required. For estimating purposes for the concrete faced dam we
suggest using only three zones: a zone of processed material under
the slab, an oversize rock zone on the downstream face, and the
remainder quarry run.
6. We concur with the tunnel alignment and suggest the section requir-
ing steel lining upstream of the powerhouse be placed as low as is
feasible to shorten the length of steel lining and to minimize the
hazard of encountering low areas in the rock cover. Rail transport
will be necessary in the tunnel which will generally require a
grade not to exceed about one percent.
7. We concur with your plan to move the powerhouse into the rock slope
to ensure rock foundations and a rock sill in the tail race to
control tail water levels at the powerhouse.
8. We concur with your decision to use cwo units only.
9. The economics of the project is dominated by the cost of the power
tunnel. Preliminary inspection of the rock from the Bull Moose and
Bradley River Fault zones indicate that most of the fault zone
material is rehealed breccia which shows neither hydrothermal
alteration nor iron staining, from surface water. Although these
zones will be crossed by the power tunnel; major support problems
are not expected but more exploration in the fault zone are neces-
sary to substantiate these opinions. To date the cores take in the
fault zone do not show the high percentage of core loss and g~uge
one would expect in such a major fault zone.
The hardness of the rock is very important in determining if a TBM
is feasible for this job. It is recommended that abrasion and
Schmidt Hammer hardness tests be conducted on representative
samples of the: 1) argillite, 2) graywacke, 3) chert and 4)
argillite with chert bands. Unconfined strengths and sonic
velocities of these materials should be determined on the same
samples used for the hardness tests.
The geologic investigation should emphasize identification of the
argillite, grawacke, and chert units in the field such that the
percentage of the proposed tunnel in each of the lithologic units
can be estimated. The hardness of these units and the length of
tunnel in each can then be used to estimate the daily progress of a
TBH. The estimate of progress is the most impor~ant factor govern-
ing the economics of the power tunnel as well as the project.
' . ... t ..
In order to make the estimate more meaningful it would also be
helpful to obtain samples from the Terror Lake Tunnel for hardness
tests. The rate of progress in that tunnel is presently being
recorded and a correlative between hardness and TBM advance costs
for the most current TB~t would add to the credibility of an esti-
mate of TBM rates for the Bradley Lake Project.
10. Undrained shear strength tests should be made of samples of the
soils of the tidal flats to provide short term shear strengths of
these materials. These data would provide a basis for designing
slopes of the barge canal and basin.
Respectively Submitted,
~-~·~)\·
A. J. Hendr<1n, Jr. rz;~ -7' ~ __.-7 -r· , / . . . ·'
· W. F. Swiger
A.JH/\.fFW I FH
\
)
)
July 18, 1983
BRADLEY LAKE HYDROELECTRIC PO~ER PROJECT
Dear Sir:
The second meeting of the Board of Consultants convened in your office
in Anchorage on July ll at 8:00am. There we were briefed on design
studies for·the Bradley Lake project.
On July 12 and 13 the site was visited. This included detailed ex-
amination of rock outcrops to correlate descriptions of the various
geologic units with laboratory tests which had been made to determine
feasibility and rates of progress which could be anticipated for
excavating the tunnel with a tunnel boring machine. The proposed
exploratory program was reviewed and drill sites visited. Both the
Bradley River Fault Zone and Bull Moose Fault Zone were examined on
foot and from the helicopter. The proposed sites of the dam at Bradley
Lake and the Power House were examined while referring to proposed
layouts for these structures.
Dam
Preliminary layouts and typical cross-sections have been developed for
the dam considering both a concrete faced rock filled embankment and a
gravity concrete dam. For either, diversion would be a gravity tunnel
through the right (north) abutment. The intake to the power tunnel
would be in the left abutment just upstream of the dam. Borrow area
for the embankment dam would be the 1270.7 ·rock hill on the left side,
a very short haul. We consider the ·proposed layouts excellent. They
·are well adapted to the geologic and topographic conditions. We note
that the embankment dam would permit lowering the low level of the lake
to about El 1065 or lower thus increasing total generation at little
cost without raising the dam. Also the spillway for the embankment dam
is a simple and economical structure, but the concrete chute should be
extended further downstream to protect the rock. This spillway design
should be considered for the concrete gravity dam in studying
comparative costs. The proposed cross-sections for the embankment dam
is satisfactory.
We understand that a brief study were made of a gravity arch structure.
However, constructing the upstream cofferdam would be difficult and
expensive and there were significant problems in providing a suitable
intake to the power tunnel. Accordingly this need not be further
considered at this time.
Powerhouse
The powerhouse is to be located north of the Corps of Engineers
cation where a rock nose offers possibility of excavating much of
tailrace in rock. Topography of the nose is being reviewed.
lo-
t he
The
2
present map is not accurate enough to locate
a field survey is necessary to locate the
tailrace will be entirely in rock. The
development is considered satisfactory.
the powerhouse and we feel
powerhouse such that the
basic, proposed plan of
Tunnel
As previously indicated, the feasibility and rates of progress of using
a tunnel boring machine are strongly influenced by the properties of
the rock being excavated. Thus to evaluate this it was necessary to:
1. Classify the rock along the line of the tunnel and determine
the amount of each rock type present.
2. Run tests on representative samples of the
types. In these tests the Schmidt Hammer
Hardness and Shore Hardness are measured.
various rock
Hardness, Abrasion
Total Hardness HT
is then defined as HR times the square root of HA where HR is
the Schmidt Hammer Hardness and HA is the abrasion hardness.
This has been correlated with penetration rates by tunnel
boring machines on a number of other projects. Tests were
also made on samples of rock from the Terror Lake Project at
locations where the penetration rates were known. Penetra-
tion rate is the advance in feet per hour of actual operation
of the machine.
The route of the tunnel was mapped by geologists of Shannon & Wilson
from outcrops along or near the alignment and a map presented showing
the distribution and extent of the several rock types present. This is
based on surface exposures only of course, but the relative amounts of
the various types present are considered adequate as a guide to the
relative amounts of the various rock types present along the tunnel
line.
A number of samples of rock from the earlier core borings were selected
as being representative of the rock types anticipated. These were
tested at the Rock Mechanics Laboratory at the University of Illinois.
Attached is a report by Dr. Hendron dated June 21, 1983 summarizing
results of the tests on the rock from the Bradley Lake and Terror Lake
projects. The tests on Terror Lake samples were conducted because the
rates of penetration with a recently designed Robbins disk cutter
machine were known. For example, the Total Hardness of samples at
station 241+59 averaged about 115 for three samples and the rate of
progress observed was 7.1 ft/hr.
Table 1 attached summarized the geologic studies and rock tests to
provide estimated penetration rates for each rock type and the estimat-
ed amounts of each type along the tunnel. Also summarized on this
table are estimates of widths of fault affected zones, gouge zones and
temporary rock support required. These were developed in conference in
your office on July 14. This table will provide a basis for compara-
tive estimates to develop project capacity.
)
,)
J
It is understood that selected samples of the several rock types will
be submitted to manufacturers of tunnel boring machines who will
provide independent estimates of penetration rates. These later data
will then be combined with Table l for use in preparing the final
estimate.
It should be noted that Table l was constructed on the assumption that
the rock described in the field as "massive argillite" was as hard as
the grayYacke. In fact the rock described in the field as massive
argillite might well be a very fine grayYacke or a metamorphosed
silicious siltstone.
These studies indicate that the tunnel can be excavated using a tunnel
boring machine. The rock here is significantly harder than that at
Terror Lake and the rate of progress will be slower but should be much
faster than drill and blast procedures.
Th.e present estimate is based on a tunnel profile Yith at 1. 5% grade
connecting to a steeply sloping shaft near the intake. The steeply
inclined portion of the tunnel can be raise bored with presently
available equipment and the same raise borer can be used to excavate
most of the surge tank and the shafts for the intake gate structure.
Boring Program
The tunnel alignment was shifted northYard at the Bradley fault in
order to cross the fault zone where the zone appeared to be narrower
from field and airphoto observations; we concur in this change and with
the present location of the boring relocated to the present position of
the tunnel crossing. We also concur with the boring located at the
Bull Moose Fault and the elimination of the boring at the powerhouse.
The boring at the powerhouse is to be replaced by surface trenches to
verify the existence of bedrock.
Summary
We were very favorably impressed by the proposed layouts and the work
accomplished. As indicated in our opinion the tunnel can be excavated
using a tunnel boring machine. Penetration rates for a TBM were
developed for the several rock types.
Respectfully submitted,
~9-~~,
A.J. Hendron, Jr.
_;7/}?:~y
W.F. Swig~
TABLE
ROCK CHARACTERISTICS & TUNNELING DATA
TUNNEL FROM D/S PORTAL TO LOWER BEND OF INCLINED SHAFT
BRADLEY LAKE HYDROELECTRIC POWER PROJECT
ALASKA POWER AUTHORITY
Length
ROCK TYPE (ft)
Graywacke &
Graywacke/Arg-illite 4300
Massive Argillite 5000
Foliated Argillite 3500
Foliated Cherty
Argillite (includes
Dacite) 3550
Chert 5xl0=50
Fault Zones
Bull Moose
Bradley River
Random
Lineament
Gouge
Bull Moose
Bradley River
Random
D/S Portal
TOTAL LENGTH
350
200
200
200
25
2x5•10
50
3x5=15
50
17500 ft.
*Additional Testing to be done
Penetration Delay
Hardness Rate (ft/hr) time
130 6* N/A
130* 6* N/A
70 13* N/A
100(est) 9* N/A
190 3* N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
130
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Drill and
Blast Section
60 days
Total ..
II
..
tt
II
tt
Re-steel through fault area #8 @ 12" E.W.
Temp.Supt
Needs
Select-
ively
located
3/4" d ia.
6' long
Mech.Anc.
2 bolts
every 4
feet for
1650 feet
=825 bolt
2/3 sets
t.'F4xl3
Full
Circle
Sets
WF5xl9
Full Sets
WF4xl3
) -. -
-------------------------------------------------------------No 4: CoH~Q& Park Court
PO. Oo• l2S
S•voy. llllno•• !>11174
Or. Gary Brierly
Stone & Webster. Inc.
P.O. Box 5406
Denver. CO 80217
Dear Gary:
Phon•·f217J JSl-8701
June 21 • 1983
J352
T~I~copy; Pill 351·6100
Tettoa: 2 iOt~·PGeoc~ntt"f Svy f
Cable: GEOCEN!ER
Enclosed is a summary of Bradley lake Rock Tests. These
include Schmidt Hardness, Shore Hardness, Abrasion Hardness,
Unit Weight, Unconfined Compressive Strength, and longitudinal
Wave Velocity test results. Calculated values of the total
hardness are also included. At present the total hardness values
are still the best index to correlate with machine tunnelling
progress. In general it appears that the total hardness values
of the argillite ranges between 50-100, while the total hardness
of the graywacke ranges from 100-150, and the values for the
chert-quartzite ranges from 170-200 .
AJH:jk
enc
••
Respectfully submitted,
~J·~f?'·
Alfred J. Hendron, Jr.
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Dr. A.J. Hendron, Jr.
28 Golf Drive
Mahomet, ILL 61853
(217) 351-8701
September 27, 1984
BRADLEY LAKE HYDROELECTRIC PROJECT
BOARD OF CONSULTANTS REPORT
Dear Sir:
W.F. Swiger
Box 388
Buhl, Idaho 83316
(208) 543-4593
The third meeting of the Board of Consultants convened in your office in
Anchorage on September 25. We were briefed on status and program of the
Phase I geotechnical investigations. We visited the site on September 26.
Further discussions were held and this report was prepared on September
27. The borings and field studies completed since our second report of
July 15, 1983 were reviewed.
G~E~
These further studies confirm the earlier preliminary design which served
as a basis for the feasibility report for the project. We conclude:
1. The powerhouse location is satisfactory.
2. The axis of the dam is satisfactory and a concrete faced embank-
ment dam is economical and preferred.
3. The tunnel can be excavated using a tunnel boring machine.
' . ' .
)
.. )
2 September 27, 1984
4. The thickness of fault zones and of gouge in the Bradley River
Fault and Bull Moose Fault are in reasonable agreement with
values previously assumed and can be tunneled through.
5. The location and proposed design of the spillway are satisfac-
tory.
6. The present geotechnical investigations are directed to develop-
ing information necessary prior to proceeding with design. We
consider the program reasonable but do make below some sug-
gestions regarding priority of the boring work and presentation
of data.
INVESTIGATIONS
The present investigations reviewed by the writers included the geologic
mapping, the drilling of exploratory core holes. and the description of
the rocks encountered in both the field mapping and the rock cores.
Core Holes
Due to the liiiifted working time available this fall, it is extremely
important to assign priority to the core holes to be completed at the high
elevations. In our opinion, first priority should be assigned to Core
Holes 9 and 14 to make sure the intake portal is in a location to provide
stable slopes. We agree that Hole 9 should be inclined southward across
the possible fault and we agree that Hole 14 should be inclined westward
and should be revised to a length of 250 feet to compensate for being
moved to a location approximately 50 feet higher than the original
location. Core Hole 16 should be the next priority in order to define the
depth of rock cover above the tunnel and to define the width of the
possible fault zone. The location of Hole 16 should be moved far enough
north in the valley in which it is located that it is located on the north
side of the hypothesized fault and that it will cross the fault if it is
inclined to the south. The present seismic surveys should be used to
locate the most advantageous position for Core Hole 16. Core Hole 43 is
next in order of priority and is necessary to define the extent of soft
(
_)
3 September 27, 1984
materials in the area of the spillway. Core Hole 17 at the gate shaft is
next in priority and is essential to furnish information on the quality of
rock at the proposed gate shaft location. To provide time for completing
the core holes listed this year, it is our recommendation that Core Holes
24 and 72 be deleted from this year's program. Core Hole 72 is not
essential to locate the depth to bedrock at the powerhouse because of the
outcrops and because of the planned trenching. Core Hole 24 is not
necessary at this time.
Early next year it is important to provide enough drill holes to determine
the location of the toe slab of the dam in order that the design may be
based on a fairly accurate geometry concerning the top of rock.
We concur that two test trenches be excavated across the powerhouse
location in order to define the top of rock. The rock discontinuities
should also be mapped such that the orientations could be used to indicate
orientation critical to any cuts in close proximity to the trenches. We
recommend the overcoring and oriented core work be deferred.
Field Mapping
We have discussed in detail the geologic mapping with R&M Consultants and
Stone & Webster personnel. One of the primary purposes of mapping in the
areas of any proposed rock cut is to document the orientation of disconti-
nuities such that appropriate wedge analyses can be conducted. It is also
helpful to describe the continuity and planarity of the surfaces and the
smoothness or roughness of these features.
Another purpose of the continuous mapping along a Northwest-Southeast
direction such as the power tunnel or access road alignment is to get an
indication of the percentage of different lithologies which will be
encountered by the tunnel. This is important because the tunnel most
likely will be bid by a contractor based upon the use of a tunnel boring
machine. The rate of progress will be sensitive to the type of rock
encountered. According to hardness tests already conducted on this study,
the hardness of the various rock types vary considerably and, therefore,
\
4 September 27, 1984
any estimate of average tunneling progress is highly dependent upon the
percentage of each rock type encountered. It is also imperative that the
rock outcrops in the field be consistently described lithologically such
that it can be determined which rock type in the field is represented by
certain laboratory core specimens selected for hardness testing.
In past mapping and testing of the rock formations at the Bradley Lake
site, ther~ have been no ambiguities concerning the descriptions in the
field or cores of rock types designated as graywacke, massive chert, or
foliated argillite. For these cases, we believe that the description of
the field outcrops and rock cores has been consistent. We believe,
however, that in past descriptions, the field outcrops described as
.. massive" argillite, a rock type which all parties agree is very hard and
silicious, may be more appropriately described as a very fine-grained
graywacke. This is important because this in effect means that a larger
percentage of the tunnel will be excavated in graywacke than was indicated
in the feasibility report. It is recommended that these materials be
described as very fine-grained graywacke when encountered. Large blocks
of this material should also be obtained from the field to enable rock
cores to be drilled for hardness tests. If these borderline materials are
described as fine-grained graywacke, then the following guidelines should
be used in designating the character of the following lithologic bands in
field mapping.
GRAYWACKE
ARGILLITE
CHERT
ARGILLITE
W/ CHERT
NODULES
DACITE
Greater than 75% graywacke, less than 25% argillite.
Greater than 75% argillite, less than 25% graywacke.
Massive chert.
Describe % of chert.
100% dacite.
f •
5 September 27, 1984
It is our opinion that the hardness tests made on rock cores described as
massive argillite and foliated argillite and which are presented in Tables
7.4-4 and 7.4-5 (S-A.J. Hendron, SWEC), are tests on samples which are
properly described as argillite. This is confirmed by the fact that the
hardness values shown for these materials in Tables 7. 4-4 and 7. 4-5 are
nearly identical. It is our opinion, however, that most of the field
outcrops mapped previously as "massive" argillite are silicious and, as
discussed above, should be classified as fine-grained graywacke. Probably
this inconsistency developed because classifying these rock in hand
specimens from outcrop is difficult. It is properly identified as
graywacke in cores because the bit cutting through the sand grains, even
though they are very fine, results in the gray color typical of graywacke.
It is nevertheless unquestionable that, whether this material is called
"silicious" or massive argillite as in past mapping or fine-grained
graywacke, it is hard, very difficult to break with a hammer and has a
hardness more in line with the 125-150 associated with graywacke than with
the range of 60-90 associated with argillite and for the purpose of
evaluating tunneling progress should be classified as graywacke.
It is suggested that the R&M geologists visit several field outcrops
previously' mapped as "massive argillite" such that they can calibrate
their current descriptions with the previous mapping.
core descriptions should also be checked.
Several previous
It is recommended that the current field mapping effort be extended next
spring and summer to map the valley just to the southeast of the tunnel
alignment from the powerhouse toward the southeast. This mapping should
be continued up and over the top along the tunnel to Bradley Lake. The
geologists should continue their practice of obtaining samples from
designated observation points so that the information is not lost and such
that discussion of rock identification can be continued in the office at
any time. The current work being done is very well documented in this
fashion and is commended.
It is suggested that Stone & Webster Engineering make the samples which
were tested for hardness at the University of Illinois available to the
)
6 September 27, 1984
R&M geologists. They should describe these samples lithologically in the
same manner currently being used. It is also suggested that a thin
section of the "massive" chert be studied to possibly refine or change
that description.
MARTIN RIVER DELTA
The Martin River Delta appears to be a good source of road and concrete
aggregate. The aggregate should be tested for possible alkali aggregate
reaction as soon as possible because of the "cherts" Yhich are found in
the formation.
Respectfully submitted,
/
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A.J. Hendron, Jr.
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November 7, 1985
BRADLEY LAKE HYDROELECTRIC PROJECT
BOARD OF CONSULTANTS -REPORT 4
The fourth meeting of the Board of Consultants convened in your office
on November 4, 1985. We were briefed on the findings of geotechnical
investigations recently completed in 1985, status of laboratory
testing programs and schedules for obtaining bids and undertaking the
project. Prior to the meeting we were provided studies of certain
action items on which our op1n1ons were requested. There was
discussion of design of the dam, tunnels, roads, barge facilities and
site work. There was a short discussion of the construction schedule.
Action Items
A. Lowering of Diversion Tunnel
Studies have been made of lowering the Diversion Tunnel to
invert elevation 1,068 and excavating the downstream Bradley
River Channel to elevation 1,060. We concur with the
Engineering studies and their recommendations that these be
done.
B. Economic Power Conduit Diameter
c.
BL-D-131
The Engineer's studies indicate 11.0 ft. ID to be the most
economic tunnel diameter. We consider this the minimum
acceptable diameter, but suggest that the diameter not
exceed 12.5 ft.
Penstock Safety Evaluation
Five proposed alternative schemes of penstock arrangement at
the powerhouse were presented. We concur that Alternative 4
as shown on SK-15500-FS-D with the tunnel and penstock grade
lowered to El 20 is the preferred arrangement.
1
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2 November 7, l'Ji:\5
D. Turbine Setting Analysis
Economic comparisons were presented of the effects of
setting the centerline of the turbines at five different
elevations from El 20 to El 10. These showed the originally
assumed setting of El iS (BLPD) to be the most economical.
We concur with setting the turbines at El 15 and installing
piping for air depression should future experience show it
to be desirable.
E. Earthquake/Tsunami Review
The outline of studies of Tsunami hazards for the powerhouse
and seiche and slide hazards in the lake were presented. We
concur that these studies are needed and that the approach
is appropriate.
Paver Tunnel
Recent failures of unlined or plain concrete pover tunnels have
occurred due to hydrofracturing in locations where the minimum
principal stress · in the rock formations is less than the static
pressure levels in the tunnels. To avoid this problem on the Bradley
Lake project we recommend that the steel lining be lengthened to a
point where the rock cover is 0.8 times the static head. We also
recommend that a hydrosplitting test be conducted at tunnel grade in a
vertical hole cored 50 feet off the centerline at station 24 + 00.
The hole should be grouted when the tests are completed. If the minor
principal stress, ~3 • determined from the hydrosplitting test is
greater than 1.2V H . , then the steel liner should be reduced in ow stat1c
length such that the end of the steel lining is at station 24 + 00.
A transition section of reinforced concrete should extend from the end
of the steel lining to station 36 + 00 where the static head and the
rock cover are approximately equal. The circumferential reinforcement
should be about 0.5 percent or one row 18 bars at 1 ft. center. The
longitudinal steel should be the normal shrinkage steel of about 0.3
percent.
Additional low modulus zones along the tunnel should also be
reinforced such as at fault zones etc. These lengths and locations
will only be known when the actual tunnel is driven and should be
designated by the engineer between the time the tunnel is driven and
when the concrete is poured. The contract must be flexible to
accommodate this process.
BL-D-131 2
)
l "Jovember 7, 19HS
We recommend re-logging of all Corps of Engineers and Shannon &
Wilson cores for lithological descriptions consistent with recent
R & M logging. This re-logging should be by the same ?ersons who did
the recent logging. An attempt should be made to develop a uniform
notation in order to minimize the re-logging effort.
~Je recommend the preparation of a preliminary outline of a
Geotechnical Report, to be included with the Phase II Contract
Documents. This outline should be available for review prior to the
next Board meeting and should be discussed at that meeting.
An NX core hole should be cored through the prominent lineation at
Station 115!. Attempt to cross the lineation in fresh rock about 100
feet below the surface. This will require about 400 feet of angled
core hole. R & M to log as above.
Preliminary data concerning the material to be
tunnel liner were presented to the Board.
considered appear to be suitable and we suggest
in final selection should be weld-ability.
DAM
used
The
that
for penstock and
three materials
the major factor
The Board requests they be furnished with existing dynamic analysis of
the dam and with details of procedures and parameters being used in
any additional analyses being made.
The Board would also appreciate being furnished detailed topography of
the toe slab contacts, especially along the right abutment. ~shall
be interested in reviewing details of joints and waters tops. We
prefer rubber with sleeve joints for wate~ stops.
Zoning of the dam should be kept to the necessary m1n1mum. We
recommend Zone 1 be about 15 feet wide. This should be well graded
material grading from not more than three-inch maxim~~ size to fines
to achieve a permeability of not more than about 10 em/sec. This
should be underlain by a Zone 2 which is 15 to 20 feet wide of rock
grading to 12-inch maximum. Care must be taken in placing this
material to prevent segregation at its contact with the Zone 1
material. These should extend to foundation level. From rock to
about 10 feet above the foundation should be select, clean rock. The
remainder of the dam may be constructed of quarry run using argillite,
graywacke and other rock types as may be present. Rock sufficiently
large that it would protrude above the surface of the lift after
compaction should be placed in the oversize zone on the downstream
slope. The boundary between the oversize and random zones should not
be fixed on the drawings.
BL-D-131 3
November 7. I 90 5
The flip bucket must be founded on sound rock. No special treatment
in the design of the flip bucket is required to accommodate small
spillway discharges; hovever the flip bucket should be designed to
drain. Drainage should be provided under the spillvay chute.
Power Intake
We suggest that the design of the intake be predicted on good
hydraulic engineering and constructibility considerations. Adequate
space is needed for a substantial rock plug, rock traps and
construction access. We believe all rock materials in the intake knob
are suitable for the quarry run sections of the dam. We concur that a
hydraulic model test of the area is required.
Schedule
For the next Board meeting revise schedule to:
a. Lengthen tunnel boring machine excavation 3 months and
revise impacted items.
b. Shorten "concrete line paver tunnel" 3 months.
c. Add "and erect" to "fab and del TBM".
Switchyard
We agree that the switchyard should be moved to the rock area
northeast of the powerhouse, thus avoiding possible liquefiable
material in the location north of the powerhouse.
Quarry
Discussions indicated present plans are to produce 70,000 cy of riprap
by quarrying 150,000 cy of dacite dike. We believe that the quarry
vill yield less riprap size material and that the under-run will not
be made-up from the access road rock excavation.
Transmission Lines
We concur with the conclusion that the number of tovers in liquefiable
soils should be minimized.
Barge Facility
We agree with the project team's conclusions regarding the concept and
location of the barge unloading facility.
BL-D-131 4
November 7, 1985
Road Cuts
We agree that 0.5:1 average slopes for the road cuts are reasonable.
For those areas where the road cuts are higher than 30ft., we suggest
however, that possible wedges formed by the intersection of only
"smooth" discontinuities, as plotted on stereonets, be checked to see
if the lines of intersection of these smooth planes are such that they
daylight into the proposed cut. If so, then the cut should be
flattened such that daylighting of unstable wedges bounded by "smooth"
planes will not occur.
Borrow Areas
We agree with the testing underway to check the adequacy of these
materials for concrete aggregate. We agree with the possible use of
low alkali • Type II cement. We concur with the engineer 1 s effort to
select borrow area to minimize the chert content.
We trust the foregoing discussion covers all of the material covered
in our meeting of November 4 and 5, 1985 and suggest the Board
reconvene on January 27, 1986.
Yours very truly,
A. J. Hendron
•.·
BL-D-131 5
,, .
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A.J. Hendron, Jr. P. E. Sperry
28 Golf Drive 21318 Las Pilas
Mahomet, IL Woodland Hills,
61853 91364
(217) 351-8701 (818) 999-1525
January 29, 1986
BRADLEY LAKE HYDROELECTRIC PROJECT
BOARD OF CONSULTANTS -REPORT 5
J. N. White W.F.Swiger
Rd PO Box 2325 Box 388
CA Boston, MA Buhl, ID
02107 83316
(208) 543-4593
The fifth meeting of the Board of Consultants convened in your office
on January 28, 198.6. We were briefed on the status of licensing and
permits for the work, schedule for the Phase I contract, status of
studies previously discussed, review of drawings and work in progress
for the Phase I contract, and ·a review of design activities for the
Phase II work.
Prior to the meeting we were furnished preliminary drawings for the
Phase I work and an agenda for the meeting. Also we were furnished a
copy of the FERC license, the Mitigation Plan, License Application to
FERC -Volume 4 "Preliminary Design Report Design Criteria -Site
Preparation Contract and an outline of the Geotechnical Report.
PHASE I CONTRACT
Barge Unloading Facilities
A review of the proposed design of the barge unloading facility was
initiated to investigate possible redesigns having lower costs.
Suggestions by the CM and R&M were reviewed. The CM suggested using
partial cells to provide a vertical face for unloading. R&M had
proposed limited use of complete cells. A primary concern in design
has been response of the structure to earthquake since liquefaction of
the underlying loose sands probably would occur. Prevention of this is
not economically feasible. Accordingly, it has been agreed this
facility will be designed and accepted as a temporary structure for
construction only.
From our review and discussions we recommend that at least two barge
unloading positions be available. Roll-off capability would be
desirable. We believe a deck elevation of about El. 16 would be
acceptable but a layer of rock should be incorporated near the top of
2-230-JJ
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2 January 29. 1986
the cells to minimize wave scour. We believe the partial cells with
tie-back sheet pile walls would be significantly more susceptible to
collapse under earthquake than complete circular sheet pile cells.
Accordingly we recommend full circle cells be used.
Possible plans were discussed. We understand R&M will make additional
layout studies considering berthing of two barges and dock width
necessary for truck turnaround and unloading cranes.
Riprap Along Roads
Present drawings of road embankments which could be subjected to wave
action are to be protected by 2 layer riprap toed into the underlying
soil. We suggest such toeing is not to be done. Rather the riprap and
filter fabric be placed directly on the existing soil surface and
carried out horizontally as considered necessary.
Present studies of haul roads for construction of the main dam show the
roads entering at the upstream face. This would require several
crossings of the toe slab for the face since this toe slab must be in
position before the fill can be placed against it. Such crossings pose
severe hazards of damaging the water stops.
We suggest this be reviewed further considering possibilities such as
alternative roads into the dam or use of a movable bridge to span the
downstream face of the toe slab.
The Board requests they be furnished with the assumptions used in the
dynamic analysis which will be used to judge the adequacy of the dam
slopes under the Maximum Design Earthquake (MOE). The critical wedges
considered should be shown; and, the calculated inelastic displacement
should be shown for each wedge considered. The basis for the selection
of the safe permissable inelastic displacement under the MOE should
also be given. The dynamic analysis should be done as soon as possible
because any change in the downstream slope would significantly affect
the area available to pass the spillway flows or the emergency low
level outlet flows.
The basis for sizing the riprap at the downstream toe of the dam must
be addressed. A hydraulic model study of the area downstream of the
dam should be conducted for this purpose.
Spillway
Based on the review presented, we believe the infrequent use of the
spillway does not require elaborate measures to protect the rock
downstream of the agee. We therefore suggest the design of the
spillway be based on the following principles:
2-230-JJ
3 January 29, 1986
1. The ogee should be straight.
2. The apron should be as short as possible and arranged to flip
the flow onto the natural rock. This should be located on
sound rock.
We recommend a hydraulic model study be conducted to investigate the
flow conditions at the downstream end of the emergency outlet tunnel
and the flow over the natural rock downstream of the spillway. The
principle need for these hydraulic model studies is to investigate flow
velocities and wave action along the toe of the dam.
BLASTING
The Board recommends that the use of "line drilling" (reference
Geotechnical Design Criteria, 12-18-85 (page 42) be changed to "cushion
blasting with guide holes." "Cushion Blasting" (page 43) should be
redefined to be nominal 3 inch holes drilled on maximum 24 inch centers
at the excavation limit, loaded lightly and fired as the last delay of
the round. A guidehole, used with cushion blasting, is drilled halfway
between each pair of cushion blasted holes. Guide holes are not
loaded. Burden on cushion holes should be 1.5 times the spacing (3'
) burden for the specified 2' loaded hole spacing).
Blast hole maximum diameter in the powerhouse/switchyard area should be
limited to 4" for excavation above El. 18 and 3" below El. 18.
It is suggested that the specification for "smooth wall blasting" in
the tunnel (page 43) include that the adjacent blast holes (first row
in from the perimeter holes) are drilled parallel to the perimeter
holes. This produces a uniform burden on the perimeter holes,
resulting in less blast damage to rock outside the excavation limit.
Considering the excellent quality of rock expected in the diversion
tunnel, this "smooth blasting" technique should produce greater than
80% half casts. The specifications could require the contractor to
change his blast design when half casts are less than 60% rather than
3 3% (page 4 3 ) •
The Board understands that the peak particle velocity criteria (page
44) will be revised. Also that Note 5, drawing 171A and Note 7,
drawing 171B will be rewritten.
There was much discussion on design assumptions and blasting
specifications for the excavation below El. 18 in the powerhouse. The
Board suggests that additional study be made of the cost of vertical
bolting reentrant corners {corners which protrude into the excavation)
plus cushion blasting with guide holes, vs. directing the contractor to
minimize damage to the remaining rock and to backfill all overbreak
with structural concrete. Report at next meeting.
2-230-JJ
)
January 29, 1986
Design recommendations are:
1. Show neat excavation line on the drawings.
2. Base the design on, and tell the contractor to anticipate
overbreak on re-entrant corners of a chamfer of 30 degrees
off vertical starting 6 feet either side of a re-entrant
corner and extending to a depth of 6 feet below the bench.
3. The factor of safety of the powerhouse against uplift should
be 1 • 05 times minimum dead weight of the structure. Use
tied own anchors, rather than relying on rock friction, to
increase FS against uplift to FERC standards.
It was agreed the excavation walls above El. 18 should be vertical.
Diversion Tunnel
The diversion tunnel upstream of the gate shaft will be concrete lined.
This liner should be contact grouted after curing with pressures of
about 50 psi. If it is desired to grout some open fracture zones
around this tunnel, the grouting should be done after the liner is
poured. The grout curtain around the tunnel just upstream of the gate
shaft should be done by grouting out from the tunnel.
Tailrace
Further study is needed on both the design slopes and the lining of the
tailrace channel. The 2:1 slopes presently proposed need to be
justified. It is our judgment that these slopes may not be
sufficiently conservative. Fabriform should be considered as an
alternate to replace the riprap which is currently the revetment
material used in the proposed design.
Aggregate
Preliminary concrete mix data were presented together with a study by
Mr. Van Epps of Stone & Webster. These showed the fine aggregate to be
harsh and rather poorly graded. The fine aggregate is too coarse. The
fineness modulus is 3.3 which is not within the limits of ASTM C-33.
The grading curve shows the material to be deficient in material
between 3/8 inch size and No. 16 and in minus 100 sizes. The design
mixes showed adequate strength but the mixes were harsh and bled
excessively. These mixes would not be pumpable.
Further studies are needed of how to assure improved grading to improve
workability and to reduce bleeding of the concrete. To minimize
problems at this time it is suggested the Phase I contractor produce
material from the Martin Creek borrow area as the available source
there dictates. Additional sources should be identified with the
2-230-JJ
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5 January 29, 1986
intent that blending sand be obtained and furnished by the Phas~ .. I
contractor as necessary for his work. Blending sand could then be
obtained and furnished by the Phase II contractor as necessary for his
work.
FERC Board Meeting
The following. list of materials should be sent to the Board as soon as
possible to enable review before the March 6 and 7 meeting.
P~ase I Specifications
Phase I Plans
Geotechnical Report without Photographs
Any other documents to be issued to Phase I bidders
It is also required that Stone & Webster propose a definite plan for
obtaining adequate quantities of concrete aggregates which satisfy the
appropriate fineness modulus values.
2-230-JJ
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6 January 29, 1986
The Board believes the above comments are self -explanatory but should
you have questions please contact us and we will respond promptly.
Yours very truly,
A. J. Hendron
/
W. F. Swiger
~~ ~White
2-230-JJ
FERC BOARD OF
CONSULTANT'S MEETING:
February 17,1986
Mr. Kenneth F. Plumb
Secretary
~
Alaska Power Authority
State of .1\losko
Federal Energy Regulatory Commission
825 North Capital Street, N.W.
Washington, D.C. 20436
FERC BOARD OF CONSULTANTS MEETING
FERC PROJECT NO. 8221-000
BRADLEY LAKE HYDROELECTRIC PROJECT
Thank you for the prompt approval of Messrs. W. F. Swiger, A. J.
Hendron, Jr., and P. E. Sperry as the Bradley Lake hydroelectric
Project FERC Board of Consultants. Per your direction, we are
initiating the selection of an electrical/mechanical engineering
consultant for FERC's approval.
The first FERC Board of Consultants meeting is presently being
scheduled for March 6 and 7. The Agenda for this meeting is attached.
The purpose of this meeting will be to review and comment on the Site
Preparation Bidding Document, Engineer's Drawings and Specifications.
The Site Preparation Contract will be issued for bid on or about March
10, 1986 and bids are to be received for this work on April 15, 1986.
Construction is scheduled to begin in late May 1986, immediately after -a contract award.
We will be forwarding for your review and comment the following Site
Preparation Contract related documents.
a. Five draft copies of the bid documents for the Site
Preparation Contract including technical specifications and
design drawings.
b. Two copies of the 1985 Geotechnical Investigation Report.
c. Five copies of. the Final Design Criteria applicable to the
facilities included in the Site Preparation Bid Documents.
2-328-JJ
PO Box 190869 701 East Tudor Rood Anchorage. Alaska 99519·0869 (907) 561· 7 8 77
Mr. Kenneth r. Plumb
rederal Energy Regulatory
Commission
2 rebruary 17 1986
d. Five sets of applicable Checked Design Calculations.
The above documents vill be reviewed as part of the March 6 and 7, 1986
Board of Consultant's meeting.
The March 6th and 7th dates were selected by the Board members as the
most suitable for an early schedule meeting. However, should these
dates present some difficulty or conflict with your requirements,
please call me at (907) 561-7877.
Very truly yours,
David R. Eberle
Project Manager
DRE/NAB/JJ
Attachment
cc: Mr. John Longacre
Mr. W. F. Swiger
Mr. A.J. Hendron,
Mr. P.E. Sperry
Mr. Arthur Martin
2-328-JJ
Jr.
AGENDA
BOARD OF CONSULTANTS
BRADLEY LAKE HYDROELECTRIC PROJECT
ALASKA POWER AUTHORITY
Meeting will be held at the offices of Stone & Webster Engineering
Corporation, 800 "A" Street, Anchorage, Alaska on March 6 and 7, 1986.
Meeting will start at 8:30 AM on scheduled dates.
MARCH 6, 1986
I. INTRODUCTION
A. Opening Remarks
B. Agenda and Overview of Meeting Discussions
II. BID DOCUMENTS FOR SITE PREPARATION CONTRACT
III. DESIGN DRAWINGS FQR S!TE PREPARATION CONTRACT
IV. fERC SUPPORTING DESIGN REPORT FOR SITE PREPARATION CONTRACT
MARCH 7. 1986
V. HYDRAULIC MODEL STQDY OF DAM SITE PLAN
VI •. .-.PRELIMINARY ANALYSIS RESULTS FQR MAIN DAM
VII. GUIDELINES fROM BOARD
VIII. BOARD PREPARES AND ISSUES ITS REPORT
2-329-JJ
A.J. Hendron, Jr.
28 Golf Drive
Mahomet, IL
61853
(217) 351-8701
Mr. D.R. Eberle
Project Manager
Alaska Power Authority
P.O. Box 190869
P. E. Sperry
21318 Las Pilas Rd
Woodland Hills, CA
91364
(818) 999-1525
Anchorage, Alaska 99519-0869
FIRST REPORT -BOARD OF CONSULTANTS
BRADLEY LAKE HYDROELECTRIC fROJECI
W.F.Swiger
Box 388
Buhl, ID
83316
(208) 543-4593
March 7, 1986
J.O. No. 15800
T2.2
The first meeting of the Board of Consultants for the Bradley Lake
Hydroelectric Project convened in the offices of Stone & Webster
Engineering Corporation at 8:30 AM on March 6, 1986. All current
members of the Board were present. Preparatory to the meeting we were
sent drafts of the Specifications, Bidding Documents and Preliminary
Drawings for the Site Preparation Contract (first phase of project)
for review and comment. A list of attendees is attached.
It is planned to place this first phase contract for bids on March 10
with bids due on April 15, 1986.
The Board presented comments and suggestions on the Specifications,
Bid Forms and Drawings. Four of the Board's recommendations are
considered especially important. These are:
1. The provisions for changed site conditions and the
consistency of wording between these provisions and
descriptions of site conditions should be reviewed.
2. It is suggested that Bid Forms and appropriate paragraphs of
the Specifications require that the Bidder certify that he
has visited the s1 te, reviewed the Geotechnical Report and
viewed the cores.
3. Environmental considerations require that material excavated
under this contract be used in construction in embankments
or wasted in specified areas. Side casting during road
construction is not permitted. Since these requirements are
unusual in highway construction, the wording of the
Specifications should be strengthened to clearly state that
side casting is prohibited and that excavation is to be end
hauled and used in necessary fill.
2-372-JJ
•
Mr. D.R. Eberle 2 March 7, 1986
Alaska Power Authority
4. The sheet pile cells of the barge handling facility, once
cell closure has been achieved, should be kept flooded to or
above the external water levels at all times to maintain
positive outward pressure until fill has been placed to
above high tide levels. Fill material of relatively clean
gravel, as is to be used here, can be placed by dropping
from a clam shell or drag line. Care should be taken to
keep the top of the fill reasonably level as the fill is
placed.
In addition to the above a number of comments on wording and details
relating to tunnel construction, blasting, grouting and concrete work
were made and notes provided to the Design Engineers.
The program for hydraulic model studies of the intake to the power
tunnel was described. A contract for this work has been placed and
construction of the model started. Scale of this model is 1:50. It
is anticipated witness testing will start about April 15. The Board
is to be kept advised of progress so that individual members may
witness the tests on the model.
We were advised of progress on preparation of the Supporting Design
Report for Site Preparation of the final Geotechnical Report and
Design Criteria.
Preliminary Dvnamic Ana1ysis for Main Dam
Preliminary results of the calculations of dynamic displacements under
the Maximum Credible Earthquake (M = 7. 5, • 75 g) were presented by
Stone & Webster for the main dam. Calculations were presented for 0 . 0 angles of shearing resistance of the rockfill ranging from 45 to 50 ;
three earthquake records were used for base motion; the amplification
of motion were considered up through the dam; and, two different
methods of calculating the yield acceleration were employed. In the
Board's opinion the calculation of the "yield" acceleration assuming a
constant vertical acceleration of 2/3 the maximum horizontal
acceleration is too conservative and not realistic. When the
horizontal motion record is used for calculating motion, it is
appropriate to calculate the yield acceleration on the basis of the
minimum dynamic resistance as defined by Newmark. This will give a
yield acceleration slightly less than the yield acceleration Stone &
Webster bas calculated when assuming the vertical acceleration to be
zero. The ranges of angles of shearing resistance considered (45° to
50°) are reasonable; but more detailed justification is required if
0 values greater than 45 are to be used in the final calculations.
The synthetic ground motion record used looks reasonable and
appropriate. An attempt should be made to acquire a "rock" record
from the recent earthquake in Mexico. The Helena record is from an
earthquake of smaller magnitude than the design earthquake. The Taft
ground motion scaled to 0. 75 g is probably conservative since it is
2-372-JJ
•
Mr. D.R. Eberle 3 March 7, 1986
Alaska Power Authority
not a rock record. However, it is from an appropriately large
earthquake (Kern County earthquake). The Board is primarily
interested in the response of critical surfaces such as those shown
for Case 2, see Fig. 1. It now appears that the dynamic displacement
of these surfaces would be on the order of 1 to 2 ft if the downstream
slope remains at 1.6:1. These values are acceptable to the Board but
more analysis of other fracture surfaces need to be conducted in order
to estimate the deflection of the concrete face as a function of depth
below the water surface.
The Board wishes to compliment the Engineers on their presentations
and their courtesy in making arrangements. We understand the next
meeting of the Board is scheduled May 28 through May 30, 1986.
Respectfully submitted,
A. J. Hendron, Jr.
2-372-J J
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