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Susitna Joint Venture
Document Number
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Please Return To
DOCUMENT CONTROL
SUSIT~~A HYDROELECTRIC PROJECT
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Prepared by:
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FY 83 PROPOSED GEOTECHNICAL
EXPLORATION PROGRAM
FINAL
JULY., 1982
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Prepared by:
SUSITNA HYDROELECTRiC PROJECT
FY 83 PROPOSED GEOTECHNICAL
EXPLORATION PROGRAM
FINAL
JULY., 1982
..__ __ ALASKA POWER AUTHORITY __
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TABLE OF CONTENTS
INTRODUCTION • • • • • • • • • 8 • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • •
DAMSITE INVESTIGATIOn • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • •
2.1 General • • • • • • • • • • • • • • • • ~ • • • • • • • • • • • • • • • • • • • • • • • • • e • • • • • •
• • • • • • • • • • • s • • • • • • e • • • • • • • • • a • • o • • • • • • • a 2.2 Civil Structures
2.3 Geologic Structur·es • • • • • • • • • • • • • • • • • • Q • • • • • • 0 • • • • • • • • • • •
2.4 Miscellaneous Investigations D D e G D D D D D ~ • D ~ D e D D D D 0 0 e D D a e e e
BORROW SITE D
3.1 General
• • • • a • • • • • • • • • • • • • • • • • • a • • • • • • • • • • • • • • • • • • • • • • • • •
• • • • • • • • o • • c • • • • • • • • • • • • • • • • • e • • • • • • • • • • • • • • • • • • •
3.2
3.3
• • • • • • • • • • • • • • • • e • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Objectives
Approach • • • • • 0 • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • •
REL{CT CHANNEL • • • • • • • • • • • • • • • • • • • • • • • • 8 • • • • • • • • • • • • • • • • • • • • • • '
4.1
4.2
4.3
• • • • • • • • a • a • • • • a • • • a • • e • • • • • • o • • • • • • • • • • • • • a • • • g • General
Gbjectives
Approach
• • e • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • e • • • •
• • • • • • • • • • • • • • • a -• • e • a a • • • • • • • a • • • • • • • a • o a a o • e • a
BORROW SITES E AND I . . . . . . . . . . . . . . . . . . . . ~ . . . . • • • • • 8 a • • • a • a • • •
5.1
5.2
5.3
e • • a • • a • • • • • • • • & a a • • • o • a • • o a • • • • • • • e • • • • • • a • u • • • • General
Objectives
Approach
• • e • • • • • • • • • • • • • • • • • • • • a • • • • • • • o • a • • • • • e • • • • • •
• • • • • • • • • • • • a • • e • c • o • • • • • • • • • • • 4 • • • • o • a • • a • • • • • a
LABORATORY TESTING • • • a • • • • a • • • • • • • • • • • • a e • • • • • • • e • • • • • • • • • • • • •
6.1
6.2
6.3
6.4
General
Damsite
• • • • • • • • • • • • • • • • • • • • • • • • • • • • e • • • • • • • • • • • • • • • • • • • •
e • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • o
Site D ~ • • • • • • • • • • • • • e • • • • • • • • • • • • Relict Channels/Borrow
Borrow Sites E and I • • • • • • • • 0 • • • • • • • ~ • • • • • • • • • • • • • • • • • • •
RESULTS OF PHASE I INVESTIGATION • • • • • • • • • • • • • • • • • • • • • • • • • • • • • •
PROJECT SCHEDULE • • a o e • • • • o • • • • • • • a • • • a o • • • a • e a • a • • a • • • a a • • e a • a
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LIST OF TABLES
NUMBER
2.1
2.,2
2.3
3.1
3.2
4.1
4.2
5 .. 1
7.1
T~TLE
Watana Damsite Geophysical Surveys
Phase I
Watana Damsite Geophysical Surveys
Phase II
Watana Damsite
Hammer Drilling Program
Watana Relict Channel/Borrow Site D
Auger Drilling Program-Phase I
Watana Relict Channel/Borrow SiteD
Hammer Drilling Program-Phase II
Fog Lakes Relict Channel
Geophysical Survey
Watana Relict Channel
Geophysical Survey -Phasae I
Borro\'1 Site E
Hammer Drilling Program w Phase II
Estimated FY83 Field Laboratory Testing
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LIST OF FIGURES
NU~1BER
2.1
2.2
3.1
3.2
4.1
4 .. 2
4.3
4.4
4 .. 5
5.1
8.1
TITLE
Watana Damsite
Proposed FY83 Exploration Plan
Watana Damsite
Geologic Map
Watana Borrow Site Map
Borrow Site D
Proposed FY83 Exploration Plan
Fog Lakes Relict Channel
Proposed FY83 Exploration Plan
Watana Relict Channel
Proposed FY83 Exploration Plan
Watana Relict Channel Profiles
Watana Relict Channel
Proposed FY83 Hammer Drill Borings
Watana Relict Channel
Expanded Thalweg Section
Borrow Site E
Proposed FY83 Exploration Plan
Geotechnical Schedule
Task 5 FY83
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1 -INTRODUCTON
This report details the proposed fiscal year 1983 (FY83) (July 1, 1982 through
June 30, 1983) Task 5 Geotechnical program for the Susitna project. The scope
of work has been directed to build upon the Task 5 Geotechnical Explorations
completed in 1981, with objectives of reinforcing the feasibility recommend~
t ions and of addressing the areas of concet·n i denti fi ed by the Acres and APA
consultant boards and review panelsa The level of effort for FY83 has been
mandated by scheduling and logistic constraints and available budget. Because
the Watana site is scheduled to be the first site developed, all FY83 activities
will be directed toward that site.
The FY83 field program will be performed in three phases. Phase I field work
will commence on July 1 and continue through September 30; Phase II will begin
in December-January and continue through March-April; and Phase III will
commence in April -May and continue through the end of fiscal year. Subsequent
phases of study would be a continuation of Phase III activities.
This report is intended to provide a detailed explanation of the scope, objec-
tive, methodology of approach 7 and schedule for the FY83 activities. It is the
intent of this report to set forth. a general exploration program to be followed,
not to 11 lock-in 11 the proposed field activities. To expedite the project, field
data will be primarily reduced and interpreted in the field. This will assist
the field personnel in guiding and revising the field studies as required to
meet the objectives of the project. Activities in the Buffalo office will
provide backup statistical analysis, revi~w and comment on the field
interpretation, and final report and draw·ing preparation. Contract preparation
and administration functions will also be supported by the Buffalo personnel.
Work performed during Phase I will be used in detailed planning of the subse-
quent phases of work. The four principal areas that will be investigated during
FY83 are:
-Relict Channels;
-Borrow Site D;
-Borrow Sites E and I; and
-Damsite.
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The FY83 program will involve a multidisciplinary approach to include geologic
mapping, geophysical explorations, subsurface investigation, and laboratory
testing. The following sections detail the scope, methods, and schedule for
Phase I. and II activities. The scope of Phase III will be dependent on informa-
tion obtained in Phases I and II, as well as budgetary constraints for the
fiscal year, and therefore are not detailed in this document.
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2 -DAMSITE INVESTIGATION
2~1 -General
The FY83 damsite investigation will be a continuation of the previous investi-
gation performed during 1980-81 programs (1980-1981 Geotechnical Report). The
principal objectives are to:
-Extend geologic mapping and confirm interpretations previously performed
on site;
-Determine depth of river alluvium beneath the proposed main dam and cofferdam;
Detail overburden depth and general rock quality in the proposed major
structure arch; and
-Determine rock condition in areas of proposed major civil structures.
The damsite investigations will consist of geologic mapping during Phase I;
seismic profiling during Phases I and II; and drilling during Phases II and III.
Details of the damsite exploration plans are shown in Figure 2.1 and are
described in Tables 2.1 through 2.3. A schedule of field activities is
contained in Section 8.
2.2 -Civil Structures
(a) Main Dam and Cofferdam Riverbed Foundations
.(i) Objectives
The objectives of this investigation will be to conduct explorations
for riverbed foundation conditions for the cofferdams and main dam~
Explorations wil"l examine both alluvial and bedrock conditions
beneath the river and on the immediate adjacent abutments. Data
from this task will be used in developing the general arrangement
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and design of the cofferdams, and represents a significant and
critical factor in determination of design parameters and criteria
for cofferdam diversion and main dam planning.
( i i) Approach
The alluvial deposits of the Susitna River, as determined to date,
consist of gravel, cobbles, and boulders with a sand matrixo The
thickness and type of material, as well as bedrock conditions, are
known at only a few locations. Development of the general arrange-
ment and design of cofferdams and the main dam wi 11 require detai 1 ed
data on the following: thickness and types of alluvial material,
frozen layers (if any), top of bedrock surface, bedrock lithology
and structure, and depth to sound rock. The FY83 investigations to
obtain this information will consist of geologic mapping, geophysi-
cal explorations, and drilling. Geologic mapping, which will be
performed during Phase I, will consist of two parts: first, exam-
ination of the geology in the immediate area of the proposed coffer-
dam locations; and, second, mapping of geologic structures on the
abutments which may affect dam and cofferdam locations and design.
Tfte 1 atter work wi 11 be discussed in a subsequent section. Geo 1 ogi c
mapping of the cofferda~ sites will consist of examining alluvial
and bedrock conditions in the immediate area of the planned loca-
tions and extrapolation of this information to tie in with informa-
tion from the damsite geologic mapping and previous explorations.
Duriuy the winter a seismic refraction survey will be performed on
the frozen river surface. The surveys will run from "The Fins" to
downstream of the 11 Fingerbuster" (upstream to downstream damsite
limits) to define the top of bedrock surface and alluvial thickness.
The seismic lines will be arranged in a grid pattern both perpendic-
ular to the dam axis and along the center of the river (Figure 2.1
and Table 2.2). The results of this survey will be the basis for
selecting river borehole locations and for refinement of the
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top-of-rock maps. Boreholes will be drilled during the winter from
the surface of the frozen river to confirm the seismic line data and
to sample alluvium and bedrock .. A "Becker" type hammer drilling,
capable of drilling 400-600 feet deep in alluvial material will be
used for the drilling and sampling. Drilling will consist of both
plug holes and sampled holes (Table 2.3)e Plug holes (holes without
systematic, deliberate sampling or coring, although sampling of the
disturbed material will be conducted for hole-logging purposes) wil~
be drilled to confirm fluvial thickness and depth to sound bedrock
as a calibration check on the seismic lines. Sampled holes will
continuously sample the alluvium and bedrock. Rock drilling, for
both plug and sampled holes, will continue until a minimum of 10
feet of sound bedrock is encountered to ensure that large boulders
are not mistaken as bedrock. A minimum of two of the holes beneath
the core of the proposed dam will be core-drilled to a depth of
50-100 feet and pressure-tested to determine rock permeability and
to assess the quality of rock at various depths.
( i i i ) S c h ed u 1 e
Geologic mapping for the cofferdam locations will be done by the
team of two geologists who conducted mapping in the damsite in 1981.
Because of the priority, this mapping will be done at the onset of
the field season in Phase lo During the winter when ice conditions
on the river are suitable, approximately 11,000 feet of seismic
lines will be run along the axis of the river and an additional
4,100 linear feet in the cofferdam areas (Table 2.2). Drilling of
the river alluvium will commence after completion of at least the
initial seismic lines. A total of four drill holes are planned for
each cofferdam site: two sample holes and two plug holes. Total
drill footage for the cofferdam sites is estimated to be 800 feet.
An additional seven drill holes will be drilled beneath the prcposed
main dam, and two holes are planned to verify the seismic refraction
data in the plunge pool area. While Table 2.3 details the assigned
priority of these holes, the actual order of drilling and number of
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(b) Portals
holes will be controlled by the effectiveness of the seismic refrac-
tion surveys and dri1ling rate. Since the river drilling program
requires a thick, stable ice cover, the drilling in the damsite area_
wi 11 be performed according to av ai 1 ab 1 e c 1 i mat i c and snow and ice
cover conditions r.ather than a fixed number of holes,
Portals include the up~cream diversion tunnel portals and downstream diver-
sion and outlet facilities, access, and tailrace tunnel portals.
(i) Objectives
The objectives of the portal investigation will be to conduct ex-
plorations for portal locations, orientations, and support require-
ments for upstream and downstream portals. Explorations will
examine and define overburden materials and bedrock conditions and
provide more definitive information on specific condi~ions at the
proposed portal areas. While very detail~d drilling and possibly
test adits will be necessary for deliberate portal design, .the FY83
program is expected to produce adequate information to allow prelim-
inary siting design for these structures.
(ii) Approach
The primary geologic structur~s which may have an effect on the up-
stream and downstream portal d~sign are the geologic structures re-
fer·red to as "The Fins" and the "Fi ngerbuster," respectively (Figure
2.2). These features will be the main focus of data gathering.
Both areas are characterized by northwest and north trending shear,
fracture, and alteration zones .. Bedrock is well exposed in "The
Fins 11 in a series of cliff faces. Outcrops are not as common in the
"Fingerbuster" where talus covers much of the area.
The investigation will examine and describe the type and thickness
of overburden material, bedrock lithology and structure, depth to
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sound bedrock, rock permeability, permafrost (if present), ground
water table, and areas of potential slope instability. Explorations
for the portals will consist of geologic mapping, seismic refraction
surveys, and drilling. Explorations will be more detailed and con-
centrated than during previous investigations. Geologic mapping
will precede other forms of exploration in the summer of FY83 (Phase
I), and will form the basis for locating seismic lines and drill
holes. Geologic mapping will consist of identifying and describing
the following: overburden material and extent, bedrock outcrop
extent, bedrock lithology, joints and joint spacings, shear,
fracture and alteration zones, and areas of potential slope insta-
bility. For the upstream portal, mapping will be done in an area
approximately 500 feet upstream and downstream from the proposed
portal locations and between river level and elevation 1,800 feet.
Mapping for the downstream portals will cover an area from the toe
of the proposed dam to the 11 Fingerbuster" shear zone, approximately
1,500 feet, and between river level and elevation 2,000 feet (Figure
2.2). Data from the mapping will be plotted on maps and sections at
enlarged scales and on joint stereo plots. These data will be
interpreted and used for further explorations and design require-
ments .
A seismic refraction survey will be run in the downstream portal
area to define overburden thickness structures and depth to sound
bedrock. Seismic lines will be run in a grid pattern based on the
results of geologic mapping (Figure 2.1). An estimated 6,600 feet
of seismic lines will be run. A 550-foot seismic line is planned at
this time for the upstream port a 1. This 1 i ne wi 11 be run on the
frozen river surface immediately offshore of "The Fins" structure
(Phase I I) .
Boreholes are planned to be drilled in both portal areas to deter-
mine type and thickness of overburden material, subsurface
conditions, rock permeability and ground water conditions.
will consist of approximately 6 to 10 predominantly angled
geologic
Dri 11 i ng
boreholes
to various depths dur1ng Phase III. Total drill footage is esti-
mated at 2,000 linear feet. Bedrock will be continuously cored, and
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core samples will be logged for lithology and structure. Selected
samples will be tested for unconfined compressive strength using a
point load tester. Following completion of the drilling, joint and
fractm"e orientations at depth wi 11 be determined using a borehole
camera. Water pressure testing will be done over the length of the
borehole to determine rock permeability. At least one borehole in
the upstream portal area-and two boreholes in the downstream portal
area will be instrumented with piezometers for ground water
monitoring.
( i i i ) S c h ed u 1 e
Geologic mapping will begin following completion of cofferdam site
mapping. One two-man team of geologists will be used for· mapping
the portal areas. Seismic surveys will be run following geologic
mapping in Phase I. Diamond core drilling would be done during
Phase I I I.
(c) Spillway and Intake Area
This area includes the entire main spillway, control structure, and
powerhouse surface areas, including the emergency spillway intake channel
area.
(i) Objectives
The objective of investigating the spillway and intake areas is to
locate any geologic features which pass through the area and might
present adverse foundation or underground support problems.
( i i) Approach
The geologic featur~s which are identified in the shear, fracture,
and alteration zone studies (Section 2.3a) will be traced where
possible into the proposed civil structure sites. Particular
emphasis will be placed on the potential work slope stability
problems in the intake and spillway channel cuts.
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The investigation will commence in Phase I with geologic mapping by
the same team that is performing the other damsite geologic mapping,
and will be followed by seismic refraction lines down the proposed
spillway centerline, flip bucket ar·ea, and general intake area. The
specific seismic refraction lines scheduled for this area of the
north abutment total 6,600 feet.
Borings in the intake facility and powerhouse area, which would be
conducted in Phase II, would be planned to explore the structure
location and simultaneously intercept any significant inferred
geologic features in the vicinity. These borings would be the same
ones discussed in Section 2.3(a)(ii).
( i i i ) S c h ed u l e
The geologic mapping wi 11 be conducted late in the Phase I program,
after the potential geologic features have been identified elsewhere
in the damsite. Seismic lines will be run before the detailed
mapping to serve as a guide for mapping. Boreholes in this area
would be drilled in Phase III8
2.3 -Geologic Structures
(a) Shear, Fracture, and Alteration Zones
The shear, fracture, and alteration zones are the northwest and noY'th
trending geologic features identified during the 1980-81 explorations •
This aspect of the explot .. ation does not include "The Fins,11 11 Fingerbuster,"
and geologic features GF7 and GF8 which will be investigated during subse-
quent detailed exploration (Figure 2.2, Section 2.3c).
(i) Objectives
The objectives of the geologic structure investigation are to pro-
vide adequate geological and geotechnical information for developing
the general arrangements. Explorations will be directed to deter-
mining the nature and extent of these geologic features on the
surface and representative cond·iti ons at depth.
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(ii) Approach
Northwest and north trending geologic structures, which include
shear, fracture, and alteration zones, were identified during
previous investigations. These features were tentatively correlated
across the site on the surface and to depth in boreholes. The FY83
investigation will attempt to confirm these geologic interpreta-
tion and further delineate the trace, continuity, and attitudes of
the less significant structures.
Principal attention will be directed to the right abutment where the
majority of civil structures are tentatively proposed.
Specific areas requ1r1rg further investigation are geologic features
GF2, GF3, and GF4, which were defined in the 1980-81 program as
potentially projecting into the proposed powerhouse intake area
(Figure 2.2).
Explorations for the nor·thwest and north trending geologic struc-
tures will consist initially of geologic mapping and seismic refrac-
tion surveys (Phase I) followed by diamond core rlrilling (Phase
III). Geologic mapping wiil precede other forms of exploration and
will be the basis for locating the seismic lines and boreholes.
Geologic mapping will consist of id€ntifying and describing the
following: type of geologic structure, orientation and extent,
degree of weathering or .31 terat ion and joint sets, and spacing.
Geologic data will be plotted on maps and sectior~ at a suitable
scale. These data will be interpreted in the field and used as the
basis for planning future explorations. Mapping will cons1st
primarily of traversing the extent of the structures and accurately
locating their positions. Cross traverses will be run across the
abutments as necessary~ Most of the traverse$ will be done on t~e
north abutment between "The Fins" and "Fingerbuster" shear zones
from river level to elevation 2,300 feet. On the south abutment,
mappingwill extend from geologic feature GFlB to GF6B and from
river :evel to elevation 2,000 feet (Figure 2.2).
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Seismic refraction lines will be run on both abutments to define the
location of low velocity zones related to shear, fracture, and
alteration zones, as well as thickness of overburden materials and
depth to sound bedrock (Figure 2.1). On the north abutment, one
seismic line will be run from "The Fins" area paralle·l to the slope
at about elevation 1,500-1,700 feet downstream to the 11 Fingerbuster 11
shear zone. This line will cross the entire abutment and all major
geologic structures. An additional seismic line at approximately
elevation 2,050 feet will connect seismic lines SL81-15 and SW-2 to
complete coverage at this elevation. An estimated 4,600 linear feet
of seismic lines will be run on this abutment. On the south bank,
one seismic line will be run eastward from the end of SL81-20
between elevation 2,000 and 2,050 feet. This line will help define
the extent of the geologic features GF3 and GF4. Line length is
approximately 2,200 lineQr feet. Seismic velocities will be plotted
on maps and sections at the same scale as geologic data. Correla-
tions will be made where possible between low seismic velocity zones
and mapped surface expressions of geologic structures.
Based on the interpretation of geologic and seismic data, boreholes
w111 be drilled (in Phase III) across various geologic structures to
verify their presence and define their subsurface characteristics.
Data will include joint spacing and, where possible, orientation,
rock permeability and strength, and ground water and permafrost
conditions. Drilling will consist of approximately 10 angled
boreholes to an average depth of 500 feet. Locations of these
borings will be based on Phase I and II activities. Boreholes may
be drilled on both abutments and crossing beneath the river.
nedrock will be continuously cored, and core samples will be logged
for lithology and structure. Selected samples will be tested for
unconfined compressive strength using a point load tester.
Following completion, fracture and joint orientation at depth may be
determined using a borehole camera and borehole geophysical logging.
Water pressure testing will be done over the length of the borehole
to determine rock permeability. Selected boreholes will be
instrumented with piezometers and thermistors for ground water and
temperature monitoring.
2-9
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(iii) Schedule
Geologic mapping will begin following portal area mapping. One
two-man team of geologists will be used for mapping on the abutments
Diamond core drilling will be done during Plase III following com-
pletion of portal area drilling.
(b) Pluton Structure
Objectives
The objective of this investigation is to establish the geologic
model for the damsite 0rea and potential quarry sources for general
site arrangements. Explorations will examine the extent of the
diorite pluton, the nature of its contacts with adjacent rock types,
and its structural relationships.
(ii) Approach
The Watana damsite is underlain by a diorite pluton which has
intruded into surrounding metasedimentary. West of the damsite, the
pluton is overlain by andesite porphyry which, in turn, appears to
be overlain by volcaniclastic rocks. The andesite porphyry has
intruded the diorite pluton. The contact between the diorite and
andesite porphyry is locally fractured with minor, local shearing.
The andesite porphyry immediately above the contact is generally
highly fractured, however, the underlying diorite is generally
unfrHctured. The ~astern boundary of the pluton has been projected
to cross through the reservoir area east of the damsite; however,
thfs contact has not been adequately defined. The pluton is cross-
cut by shear, fracture, and alteration zones. The origin of these
zones, whether due to regional tectonic forces, local pluton related
forces, or a combination of the two, has not been determined.
2-10
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Understanding of the lithology, structure, and contacts of the
pluton and surrounding rocks requires the preparation of a geologic
model of the development of the diorite pluton and surrounding rocks
in the damsite area. The geologic model can be used to predict the
nature and extent of various lithologies and structures where there
is a scarcity of data.
Explorations for the development of a geologic model for pluton
structure will consist of geologic mapping based on previous invest-
igations. Mapping will consist of describing and defining the lim-
its of diorite pluton, nature of lithologic contacts, nature of geo-
logic structures at the contacts, and extent of geologic structures
away from the main damsite. Geologic mapping will be done upstream
and downstream from the damsite along the Susitna River, on Tsusena
and Deadman Creeks, in Quarry Site A, and any other suitable
locations as determined by aerial reconnaissance. Geologic mapping
for this investigation will not require the level of detail or
control as that done for the portals, cofferdams or shear, fracture,
at1d alteration zones. Detail airphoto interpretation will be done
prior to mappin; to identify locations to be mapped.
In addition, detailed petrographic studies and age dating may be
performed on various rock types collected during the mapping program
to determine mineralogy, lithology, and the sequence of geologic
events.
( i i i ) S c h ed u 1 e
Geologic mapping for pluton structures wi 11 :~equire a team of two
geologists during Phase I.
(c) "The Fins" and "Fingerbuster 11
(i) Objectives
The objective of this investigation is to complete explorations of
these geologic features for general arrangements and design of un-
2-11
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der~;'ound ci vi 1 structures. Exp l0rati ons wi 11 examine and define
the surface and subsurface nature and extent of these features .
(ii) Approach
11 The Fins" and "Fingerbuster 11 bound the damsite on the upstream and
downstream sides, respectively (Figure 2.2). Both features contain
major northwest and north trending shears, fractures, and alteration
zones which would have a significant impact on costs for any civil
structures located within themo At present, these structures have
been identified on the north abutment and tentatively projected to
the south bank based on correlation with boreholes, seismic data,
and topography. This investigation wi11 attempt to confirm these
correlations and define and describe, in detail, the surface and
subsurface characteristics of these features. Explorations will
consist initia11y of geologic mapping, followed by seismic refrac-
tion surveys (Phase I and II) and diamond core drilling (Phase III).
Geologic mapping will be the basis for locating seismic lines and
boreholes. Mapping will consist of identifying and describing the
following: type of geologic structure, orientation and extent,
degree of weathering or alteration, and joint sets, continuity, and
spacing. Geologic data will be plotted on maps and sections at
suitable scales. This data will be interpreted in the field for use
in planning further explorations. Geologic mapping will consist of
tracing the extent of these features by ground traverses and aerial
reconnaissance. Mapping on the north bank will extend from the
Susitna River to Tsusena Creek. On the.south bank, limited outcrops
restrict mapping to within about one mile of the river.
Seismic refraction lines will be run in both "The Fins 11 and 11 Finger-
buster" areas to define the extent of low seismic velocity zones re-
lated to these features, thickness of overburden, and depth to sound
bedrock. The amount and location of seismic lines is dependent on
the results of geologic mapping. An estimated 3,300 linear feet are
·planned for 11 The Fins 11 and 3,300 linear feet for the 11 Fingerbuster"
(Figure 2.1).
2-12
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derground civil structures. Explorations will examine and define
the surface and subsurface·nature and extent of these features.
(ii) Approach
11 The Fi ns 11 and "Fi ngerbuster 11 bo . .md the damsite on the upstream and
downstream sides, respectively (Figure 2.2). Both features contain
major northwest and north trending shears, fractures, and alteration
zones which would have a significant impact on costs for any civil
structures located within them. At present, these structures have
been identified on the north abutment and tentatively projected to
the south bank based on correlation with boreholes, seismic data,
and topography. This investigation will attempt to confirm these
correlations and define and describe, in detail, the surface and
subsurface characteristics of these features. Explorations will
consist initially of geologic mapping, followed by seismic refrac-
tion surveys (Phase I and II) and diamond core drilling (Phase III).
Geologic mapping will be the basis for locating seismic lines and
boreholes. Mapping will consist of identifying and describing the
following: type of geologic structure, orientation and extent"
degree of weathering or alteration, and joint sets, contir.u1ty, and
spacing. Geologic data will be plotted on maps and sections at
suitable scales. This data will be interpreted in the field f~r use
in planning further explorations. Geologic mapping will consist of
tracing the extent of these features by ground traverses and aerial
reconnaissance. Mapping on the north bank will extend from the
Susitna River to Tsusena Creek. On the.south bank, limited outcrops
restrict mapping to within about one mile of the river.
Seismic refraction lines will be run in both 11 The Fins 11 and 11 Finger-
bustern areas to define the extent of low seismic velocity zones re-
lated to these features, thickness of overburden, and depth to sound
bedrock. The amount and location of seismic lines is dependent on
the results of geologic mapping. An estimated 3,300 linear feet are
'planned for "The Fins 11 and 3,300 linear feet for the "Fingerbuster"
(Figure 2.1).
2-12
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( i i i ) S c h ed u 1 e
Geologic mapping of "The Fins" and "Fingerbuster" is planned during
Phase I with two geologists forming a team.
2.4 -Miscellaneous Investigations
(a) Instrumentation of Existing Boreholes
(i) Objectiv=s ·
( i i)
The objective of these explorations is to gain additional data on
ground water and permafrost conditions in the bedrock at the main
damsite.for design and construction activities.
Approach
To complete the 1980-1981 instrumentation program at the damsite
requires installation of additional piezometers and thermistors. At
present~ thermistors are located on the north abutment in BH-3 and
BH-6. It is proposed that a thermistor string be installed in BH-8
( dri 11 ed in 1981) to eva 1 uate permafrost conditions on the south
abutment. ihermistor construction would be the same as the existing
units with 16 thermistor points along a 250 foot cable.
Two piezometer installations are proposed for special conditions in
Borehoies BH-4 and BH-12. A pneumatic piezometer tip will be in-
stalled at the elevation of the powerhouse in BH-4 to determine
water pressure conditions at this depth. In BH-12, a pneumatic
piezometer tip will be installed below the artesian aquifier at
about 400 feet.
To install the piezometers and thermistors, boreholes BH-4, BH-8,
and BH-12 will have to be reamed out to the required depths to allow
placement. Approximately 1,690 feet of reaming will be required.
2-13
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This work will be undertaken during Phase III.
(b) Survey Control
( i) Objective
The objective of establishing survey control is to establish ade-
quate ground control for use in damsite investigations and to
control the field mapping activities.
( i i) Approach
Upon comm~ncing work in July, a survey grid will be established on
both abutments and along the river for ground control. The grid
will be on an average of 500-foot spacing with permanent markers
established at designed locationso The grid will be tied into the
state of Alaska grid system, which is the system establ1shed at the
site in 1980-81.
All field exploration performed on the damsite will be controlled by
the surveyed grid.
(iii) Schedule
Work on establishing the grid will be undertaken in the early part
of Phase I.
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Seismic
Refraction
line No.*
SLB2-D***
SLB2-E
Sl82-F
SL82-G
SL82-H
Sl82-I
SL82-J
SL82-Ka
Sl82-Kb
Sl82-L
SL82-M
SLB2-N
Sl82-0
Sl82-P
Sl82-Q
SL82-R
TABLE 2.1: FY83 EXPLORATORY ~ROGRAM-PHASE I
WATANA DAMSITE GEOPHYSICAL SURVEYS
location**
Downstream Portals,
BH-6 towards BH-2
Downstream Portals,
DM-C to SW2
Downstream Portals,
SW-2 to river
Flip Bucket, Spillway
Area Rack Stability
Downstream Portals,
mid olope
DH-9 to SLB0-·2
Spillway
North Abutment
Upstream North Abutment
Powerhouse· Area
Upstream South Abutment
~arth Abutment, Sl81-15
to SW-2
North Abutment
Upstream South Abutment
Downstream Portal Area,
Right Bank
Downstream Portal Area,
Right 5ank
Approximate
length (ft)
2,200
1 '100
1,100
1,100
2,200
1,100
4,400
2,200
1,100
2,200
2,200
1,300
1 '100
1,100
1' 100
TOTAL 26,600
Purpose
Depth to bedrock, overburden thickness.
Overburden thickness, bedrock conditions.
Overburden thickness, bedrock conditions.
Overburden thickness, bedrock conditions
in "Fingerbusterll.
Overburden thickness, bedrock conditions,
NW and N shears.
Overburden thickness, bedrock conditions,
NW and N shears, overall slope stability.
Overburden thickness, bedrock conditions,
NW and N shears.
Overburden thickness, bedrock conditions,
NW and N shears.
"The Fins," NW and N shears.
"The Fins," NW and N shears.
NW and N shears.
NW and N shears.
11 The Fins," and possible east-trending
structures.
"The Fins"~
11 Fingerbuster".
*Seismic lines listed in order of priority, seismic lines Sl82-A through C are listed an Table 4.2. **See Figure 2.1.
***Upon execution of work, temporary line letters will be replaced with a permanent chronologi~ally sequential line number.
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Seismic
Refraction
Line No.
SL83-AA*
SL83-BB
SL83-CC
SL83-DD
SL83-EE
SL83-Ff
SL83-GG
SL83-HH
Sl82-II
SL83-JJ
SL83-KK
SL83-LL
SL83-MM
SL83-NN
SL83-00
1ABLE 2.2: FY83 EXPLORATORY PROGRAM -PHASE II
WATANA DAMSITE GEOPHYSICAL SURVEY
Location
Upstream Cofferdam
Centerline
Upstream Cofferdam,
River Centerline
Main Dam Centerline
Downstream Cofferdam,
Ri ver.• Center line
Downstream Cofferdam
Downstream Cofferdam
Centerline
Upstream Portal
Main Dam River
C~'-'*"erline
Main Dam Upstream Toe
Main Dam Upstream of
Centerline
Main Dam Downstream of
Centerline
Main Dam Downstream Toe
Plunge Pool
Plunge Pool
Plunge Pool
TOTAL
Approximate
Length (ft)
800
1,100
500
1,100
550
550
550
3,850
550
550
400
550
500
1,100
2,200
14,850
Purpose
Depth of overburden and bedrock conditions.
Depth of overburden, bedrock conditions,
and "The Fins".
Depth of overburden and bedrock conditions.
Depth of overburdenr bedrock co~~itions,
and "Fingerbuster".
Depth of overburden, t~drock conditions,
Depth of overburden, bedrock conditions,
and "Fingerbuster".
Depth of overburden, bedrock c~nditions,
and "The fins".
Depth of overburden, bedrock conditions,
and NW and N shears.
Depth of overburden and bedrock conditions.
Depth of overburden and bedrock conditions.
Depth of overburden and bedrock conditions.
Depth of overburden, bedrock conditions,
and "Fingerbuster".
Depth of overburden~· bedrock conditions,
and "fi;,gerbuster 11 •
Depth of overburden, bedrock conditions,
and "fingerbuster".
Depth of overburdP.n, bedrock conditions,
and "Fingerbuster~.
*Upon execution of work, temporary line letter designation will be replced with a permanent
chronologically sequential line number.
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TABLE 2.3: FY83 EXPLORATORY PROGRAM
Drill Hole*
Number location**
Upstream Cofferdam
HD-AA**** Sl81-4, SLB1-5
HD-88 Sl83-88
HD-CC SL81-5
HD-DD SL83-AA and SL83-88
Main Dam
HD-EE Center line SL8.3-CC
HO-ff Centerline Sl83-CC
.and Sl83-HH
HD-GG Centerline Sl83-CC
Downstream Cofferdam
HD-HH Sl83-DD
HD-II Sl83-ff
HD-JJ
HD-KK
~~stream Portals
HD-ll
HD-MM
HD-NN
Main Dam
HD-00
HD-PP
HD-QQ
HD-RR
SL83-ff
Sl83-EE and SL83-DD
SL83-GG
SL83-GG
Sl83-88
Upstream Toe,
SL83-HH and SL83-II
Sl83-JJ
and Sl83-HH
Sl81-16
Downstream Toe,
Sl83-HH and SLB3-II
WATANA DAMSITE HAMMER DRILLING PROGRAM
Approximate
Depth (ft)***
110
120
90
100
85
130
95
110
95
75
80
70
70
100
100
130
100
130
Sampling
Alluvium
and rock
Alluvium
and rock
Alluvium
Alluvium
Alluvium
Alluvium
and rock
Alluvium
Alluvium
and rock
Alluvium
Alluvium
and rock
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
Alluvium
and rock
Alluvium
Alluvium
and rock
Pt~rpose
Overburden material and
thickness, bedrock surface,
lithology and structure.
Same as above.
Overburden material and
thickness.
Same as above.
Same as above.
Overburden material and
thickness; bedrock surface,
lithology and structure.
Overburden material and
thickness.
Overburden material and
thickness; bedrock surface,
lithology, and structure.
Overburden material and
thickness.
Overburden material and
thickness; bedrock surface,
lithology, and structure.
Overburden material and
thickness.
Same as above.
Same as above.
Same as above.
Same as above.
Overburden material and
thickness; bedrock surface,
lithology and structure.
Overburden material and
thickness.
Overburden material and
thickness; bedrock surface,
lithology and structure.
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Drill Hole*
Number
Plunge Pool
~55
HD-TT
Location**
SL83-MM
SL83-MM and
Approximate
Depth (ft)***
90
90
Sampling Purpose
Alluvium Overburden material and
thickness.
Alluvium Overburden material and
SL83-00 and rock thickness; bedrock surface,
TOTAL
*Borings listed by priority.
**See Figure 2.1
lithology and structure.
1,970
***Assume 10 feet of rock drilling except 40 feet where rack will be sampled.
****Upon execution of work, temporary boring letter desigr.dtion will be replaced with a
permanent chronologically sequential hole number.
Note: While this table lists priority sequence, holes will not necessarily be
drilled in this order, depending on ice conditions, weather, and drilling
progresso
• 3,22S,OOO --
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REFERENCE BASE MAP FROM COE,197B-I" •200'
CC .. TINliES OFF'
PAGE
WATANA TOPO(;RAPHY,SHEET 8613
OF 26,COOROINATES IN F!::ET, ALASKA
STATE PLANE (ZONE4l
LEGEND
BOREHOLES AND TEST PITS•
Y PROJECTIONS AS SHOWN
m OIH t978,COE JOIAMONO CORE BORING,HORIZONTAL
BH• 8 l96v·B~AAI
M TPRil 1981,AAI BACKHOE TEST PIT
GEOPHYSICAL SURVEYS•
& SW·l SEISMIC REFR14CTION SURVEY END
OR TURNING POIN'r
DM•C: 1975, DAMES a MOORE
SW·I 197B,SHANNON a WILSON
Sl. 80-1 1280·81, WOODWARD•CLYDE CONSULTANTS
PROPOSeD BOREHOLES:
(3HD·AA HAMMER DRILL BORING
PROPOSED GEOPHYSICAL SURVE'f:
~SEISMIC REFRACTION LINE· PHASE :t
8SL83·AA~ SEISMIC REFRACTION LliiE•PHASE lt
(DASHED LINES ARE OPTIONAL)
NOTE
t, SEISMIC REFRACTION LINES SLBa·A THROUGH SLB<! •C
ARE SHOWN ON FIGURE <I.Z.
CONTINUES
OFF PAGE
300' _,.,.,.
1:\ --,....... --
// ---
/ --
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Li::GEND
LITHOLOGY:
CJ
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DIORITE Til OUA M:NOR Gf!At.?O~T~IORITE, INCLUOES
ANDESITE POR~H MINOR DACITE' .. ~Y,INCLUOES ·~•D LATITE
DIORITE PORPHYi'Y
CONTACTS:
__!~ LITHOLOGIC 0 DIP WHERE' I<~~~~D \VfiERE l"lFERRED,
STRUCTURE:
f".?'-':""=1 !:::.~
YX
r:::· ::=,J
1-a;...;::)
:.~;;.-
OTHER:
SHEAR WIDTH G VERTtcAt.. UNLES:~');~ TUAII 10 FE'c.T,
SHEAR WIOTfi HOV.'N
;NCLINED, VERT~E TEHAN 10 FEET KNOWN • XTENT 'ftnERE
FRACTURE ZONE
10 FEET, VERTICAL ~~~s~REATER TfiAN
FRACTURE DIP SHOWN ~.fe:W·~~~~~b~~h~ltfC5Eirl~
JOINTS.JNCLIN ~RTICAL I SET~0 •1 Ot,;~NI INCLINED,
XCEPT FOR OPEN JOIJT~~LY,
At:rERATION ZONE WIO-.u ' on AS SHOWN
6 WJ-I JOit!T STATION
@]) GEOLOGIC fEATURE
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3 -BORROW SITE D
3.1 -General
Borrow Site D has been identified as a zone ranging from 2,000-6,000 feet in
north-south dimension, stretching over 12:000 feet from a point on Deadman Creek
to the approximate thalweg of the relict channel, including approximately 7,000
feet of exposure as bluffs overlooking the Susitna River, for a total area of
about 1,075 acres (Figures 3.1 and 3.2). The area has been identified as the
most favorable source for impervious core material for a total estimated site
requirement of approximately 8.25 mcy. The information to date on the borrow
site comprises seismic refraction surveys, auger holes, several deep rotary
drill holes, and shallow test pits.
3.2 -Objectives
The objectives of the FY83 program are to obtain sufficient details to confi~m
the stratigraphy developed during feasibility, and to develop a clear under-
standing of material properties, ground water, and permafrost conditions.
Results of the FY83 will form the oasis for the subsequent detailed design level
investigations. The long-range objective of the Borrow Site D i~vestigations
will be to determine:
(a) Borrow site stratigraphy and extent of each of the various identified units
of interest to a level adequate to develop volume-distance relationships,
stripping parameters, and producible volumes.
(b) Define site and adjoining areas, ground water, and permafrost conditions in
order to allow optimization of production methodology, mining method, and
water/frost handling.
(c) Limits of desired excavation based on geologic conditions and desired
material properties and determination of mining methods.
(d) Continuity of material properties and their influence on production,
processing, and placement requirements.
3-1
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(e) Engineering properties of the mater·ial as required for placement in the
fill, including placement water content, gradation, plasticity, and
compaction characteristics. Explorations will place emphasis on detailing
volumes of reserve with vario~s properties to allow for selectivity in
production, if necessary.
3.3 ~ Approach
Since Borrow Site D lies within the relict channel area, the exploration for
borrow materials will also provide desired information on the relict channel
stratigraphy.
The Phase I summer explorations on Borrow SiteD will be limited to: surficial
outcrop mapping during early summer to delineate exposed borrow materials and
bedrock; a.seismic refraction survey in both the borrow area and relict channel;
and an auger/rotary drilling program which is intended to provide high quality
split spoon and "undisturbed .. core samples to a depth of approximately 200 feet
(Figure 3.2 and Table 3.1). The drilling will be performed with helicopter-
transportable rigs equipped with a variety of drill tools enabling it to utilize
rotary drilling with casing, hollow stem auger, and conventional wireline coring
methods of advance. It is planned that each boring will commence with large
diameter casing capable of obtaining 3-inch samples to an-approximate depth of
75 feet. It is anticipated that from 100 to 200 feet the auger system will not
be effective; therefore, a wireline drill rod will be used with a "casing
advancer 11 rotary tricone bit. Depending on drilling difficulty and sample
recovery, it is likely that this method will, in a large portion, replace the
augering method of advance. Normal advance procedure will involve taking of
frequent samples, as described in a subsequent paragraph, with rotary drilling
to overcome boulders and cobble zones and to advance between samples. Proposed
borehole and seismic line locations are shown ih Figure 3.2. The information
collected during the summer program will be used to locate the drill sites for
the 1 arger· diameter hammer dri 11 boring to be conducted in the wi ntet~ when over-
land access is possible.
The winter Phase II program will be conducted as part of the relict channel
exploration program and will involve use of a large hammer drill with large
3-2
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inside diameter (6-inch) drill pipe (Figure 3.2 and Table 3.2). Continuous
sampling of the blown out cuttings will provide large samples of the various
stratigraphic units for use in ~~ologic interpretation of the stratigraphy and
in materials laboratory testing. In addition, drive and core type samples will
be taken at selected intervals.
The drilling program in Borrow SiteD will be directed to:
Obtaining information on the stratigraphy in relict channel and borrow site;
and;
Obtaining bulk samples of the potential borrow materials for subsequent
testing.
Due to the primary need for stratigraphic information and the fact that syste-
matic pattern explorations of the borrow reserves will be conducted in the sub-
sequent stage of design investigations, the emphasis of the FY83 program will be
put on stratigraphic data collection. The sampling and instrumentation activi-
ties carried out in this program will be directed at maximizing the level of
information obtained from each boring. Instrumentation will be installed to
pv-ovide baseline thermal and geohydrologic data. The various methods that will
be utilized are described individually below:
fj (a) Full depth sampling to provide material for geologic examination of the
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larger particle sizes and for laboratory testing.
(b) !1rive and core type samp.ling as is ""ppropriate using 2-and 3-inch standard
split spoon with standard penetration blow counts. Denison sampling, and
dry-blocked and conventional fluid circulation core barrel sampling will be
conducted.
(c) Casing drive tests (open casing 1rive tests) for general correlation of
stratigraphy and density.
(d) "Undisturbed .. samples, using such samplers as fixed piston, "Osterberg,"
"Shelby, .. <:nd other special split and tube type barrel samples.
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(e) Water level detection and monitoring both during and after drilling to
detect various aquifers, perched water zones, and 11 dry11 zones. Due to the
preliminary indications that the area hds a complex system of ground water
levels, most borings will have a minimum of a standpipe type piezometer,
and those which penetrate a definite zone of interest may have pneumatic or
electric piezometers installed. This system of observation points will be
correlated with the relict channel installations.
(f) Limited aquifer permeability testing such as falling head and/or constant
head tests will be performed where possible to obtain order-of-magnitude
information on the ranges of permeabilities of the materials in the borrow
site8
(g) Permafrost detection will be limited to observation of both seasonal and
permanent frost during drilling and installation of thermistors in most of
the holes. The probes will enable detection of permafrost in the following
year after the frost has stabilized, and of the depth of annual frost pene-
tration during the winter. This information will be utilized to evaluate
the frost conditions likely to be encountered in 9xcavation and, at a later
stage of design, will be used with the results ~; all thermal investiga-
tions data to develop the borrow site productirin method to minimize the
adverse effects of the frost in excavation and fill placement.
(h) Depending on the variability of the stratigraphic units and material
properties across the ~~ea, and the confidence in the geologic interpreta-
tion from recoverd samples, downhole geophysical logging may be conducted.
PVC plastic pipe will be installed in the borehol~s to allow logging at the
end of Phase I or Ph~se II, if it is deemed appropriate at that time.
(i) Depending on the nature of the materials encountered, special vane, core,
or downhole insite density measurement testing may be performed in the
boreholes. Standard penetration and tube sample density will be performed
as a routine form of testing.
3-4
't~ 'f
~ . '
r
l~'
TABLE 3.1 (Cont'd)
Boring*
Number
AH-Y**
A H-Z
AH-AA
AH-BB
AH-CC
AH-DD**
AH-EE
AH-FF
AH-GG
AH-HH
AH-II
AH-JJ
AH-KK
AH-ll
AH-MM
AH-00
AH-PP**
Approximate
location***
D/RC on SL81-6
D on SW-3
RC between DR-26
and DR-22
RC on Sl81-13
RC on SL80-1
RC on Sl82-B
RC on DM·-A
D/RC near AH-D-8
D on DM-A
D near AN-D-10
and AN-D-11
D near AP-18
D between AP-10
and AP-11
D nec;r TP-14
D near TP-10
RC on SL81-14
D/RC on DM-A
D on DM-A
RC near DR-20
RC near Sl81-15
D near SL81-19
D, SW of RR
D, near TP-13
Depth ( ft)
Assume all drill
holes to 150 feet
Same as above
Same as above
Same as above
Same as above.
Same as above ..
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as abo~e.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Instrumentation
SP
SP
P = 2, SP
P = 2, SP
SP
S?
p :: 1
p = 3
SP
SP
p = 1
SP
p = 1
SP
P:1
SP
SP
SP
SP
SP
SP
SP
Purpose
Add detail to stratigraphy
and material properties.
Same as above.
Same as above.
Same as above.
Same as aboveo
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as abo¥e.
Same as above.
Same as above.
Same as above.
Same as above.
AH-QQ
AH-RR
AH-SS
AH-TT
AH-UU
AH-VV
AH-WW
AH-XX
Miscellaneous, locations to be determined
in field~ also for more detailed investigation
of freeboard dike.
*Borings listed by priority.
·HAuger borings adjacent to hammer drill holes ..
***See Figures 3.2 and 4.2.
D = Borrow Site D
P = Piezometer tips (pneumatic) RC = Watana Relict Channel
SP = Standpipe Piezometer
T = Thermistors
Note: Standpipe piezometers may be largely replaced in the pneumatic piezometers depending
on installation depth and cost. Quantities shown are maximum possible requirement.
r
r:
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-"
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TABLE 3.2: FY83 EXPLORATORY PROGRAM -PHASE II
WATANA RELICT CHANNEL/BORROW SITE D
HAMMER DRILLING PROGRAM
Boring*
Number
HD-A
HD-8
HO-C
HD-D
HD-F
HD-G
HD-H
HD-I
HD-J
HD-K
HD-L
HO-M
HD-N
Approximate
Location***
RC on SLB0-1
near AH-H
RC on SL82-A
near AH-I
RC on SL82-B
near AH-K
RC on SL82-B
near AH-DD
RC near DR-20,
and AH-PP
RC on SLB0-2
RC on SW-3
D/RC on SL81-6
near AH-Y
RC near AH-0
RC on SL81-14 and
SL82-C, near AH-T
D/RC on DM-A,
near AH-NN
D/RC near TP-21
and AH-N
D on SLB0-8, near
AH-S
D on SW-4
TOTAL
Approximate
Depth ( ft)
200'
100
450
300
225
50
150
425
425
525
225
400
600
250
4,325
*Borings listed by priority.
**Auger borings ~djacent to hammer drill holes.
***See Figures 3.2 and 4.2.
D = Borrow Site D
P = Piezometer tips (pneumatic)
RC = Relict Channel
SP = Standpipe Pie~ometer
T = Thermistors
Instrumentation*** Puq~ose
p = J Stratigraphy material, T properties, ground water,
and permeability.
p = 2 Same as above. On main T thalweg.
p = 5 Same as above.
p = 3 Same as above.
p = 3
T
Same as above.
p = 3 Same as above.
p = 2 Same as above.
p = 5 Same as above.
p = 5 Same as above.
T
p = 5 Same as above. r
p = 3 Same as above.
p = 5
T
Same as above.
p = 3 Same as above.
T
p = 3 Same as above.
P = 50 tips, allow 20 additional tips for
miscellaneous locations.
T = 7 strings, allow 3 additional strings for
miscellaneous locations.
BO WATA~~A
RROW SITE MAP
LOCATION MAP
--
LEGEND c--__ ::J BORROW/QUA RRY LIMITS
FIGURE 3 .1
Ct'NTOiJRS OI.IITTE
FOR CI.A'iiTY 0
<SEISW. UN"' BORROW fEET TO ~~IT.~~ u.ooo
PROPOSED SITE 0 "'"'
FY83 EXPLORATION PLAN
® AH·D·I
® AH·D-6
~
.._ LEGEND AH·NN7HO·K . .._
~\/0,..,.;-;::•c::;,.. •m """
-:/ _) 'c~l HYSICAL S ~ £sW·3 URVEYS• "Co SEISMIC REF! =---:;:::--.,. OM. A 1975 UICTION SURVEY EN
,"<!: ~~ ... , " • "'"' • """" """ '"""' """ 22~~ Sl 78, SHANNON a '"""" .... ..,... """' B • WOODWARD
('._ •'OREHOLES AND TEST ·CLYDE CONSULTANTS
... ""-,.:-.. . 0 OR·Z7 1"78 PITS• '""""'~):-.. . n. • ' COE ROTAR -"\:;~ ""AP-2.1 1978 y DRILL BORING
®AH-D-121 • COE AUGER BORING
SBO,AAI A
\ 1111 TP•II 1978 UGER BORING
•di:361T-=> .., • COE BACKH AH·D· '" .., BULK S OE !EST PIT AMPLE LO
PROPOSED CATtON I BOREHOLES•
__, QAH•A
__)
0HO·L AUGER BORING
HAMMER ORIL
5
!'!.Q:!!. L BORING
l HAMMER DRILL AUGER E!ORINGSBORINGS ARE LOCAT • z= EO ADJACENT TO
c /"'"'
I
FIGURE 3.2
4 -RELICT CHANNEL
4ol -General
Two areas have been identified on the banks of the proposed Watana reservoir
where bedrock falls below the proposed reservoir elevation and, hence, provides
a potential for reservoir leakageo The preliminary explorations and geologic
mapping indicate that both of these areas may be abandoned Susitna River chan-
nels or 11 relict channels", one between Deadman and Tsusena Creeks, and the
second in the Fog Lakes area.
The potential concerns regarding these areas are~
[
1 (a) Potentia 1 for excessive reservoir 1 eak age of such magnitude as to affect tJ
(b)
l
:J
project economics.
Potential for excessive local gradients under reservoir head which might
cause piping of material and, hence, induce progressive failure of the rim
material with ultimate breaching of the reservoir.
~1 (c) Overburden instability or seismic liquefaction potential which could result
II l
'j '
I' 1 !,,.:o_
f :l
' ' ' ' L..i.
! I
in breaching of the reservoir confinement.
(d) Crest settlement due to saturation and permafrost thawing.
4.2 -Objectives
The objective at ths FY83 program will be to assess the potential for these
occurrences. The following factors must be adequately defined to allow proper
evaluation of the ,Jhysical behavior of the relict channels under project
operating conditions.
-Stratigraphy;
L~ Material properties;
Boundary conditions;
' '
' : J
I . '.1
I I
. f
.. ,
u.
-Geohydrology;
Permafrost conditions; and
-In-situ physical condition of materials.
4 .. 3 -Appr'oacb_
A two-phase program of exploration is proposed. The FY83 program will primarily
address the more critical Deadman-Tsusena area relict channel which has been
designated as the Watana Relict Channel. Preliminary assessment of the Fog
Lakes Channel shows the freeboard at Fog Lakes is significantly higher than the
Watana Relict Channel, and the local and overall gradient is much flatter and
the flow path much longer than the Watana Relict Channel, which minimizes any
hazard. It is therefore proposed to do only 1 imi ted seismic refraction i nvesti-
gations in the Fog Lakes areas during FY83, with a more intense investigation
being performed in the area during FY84 if needed (Figure 4.1 and Table 4.1).
These investigations will be conducted to assure that significant flow paths or
liquefiable zones are not present in the Fog Lakes Relict Channel.
The Watana Relict Channel has a flow path of approximately 1 to 2 miles with an
average gradient of about ten percent and a stratigrap~y wh;ch (based on the
information to date) indicates potential for seepage. In addition, very limited
subsurface data suggest that potentially liquefiable material may be present
within the channel.
The FY83 explorations will be jointly conducted with the Borrow Site 0 program
since the borrow site lies within the confines of the relict channel areas (Sec-
tion 3). The principal objective of the FY83 program is to: obtain representa-
tive samples for stratigraphic identification; define material properties
distribution; and determine geohydrologic conditions in the re:lict channel •
The FY83 program for the relict channel will be performed i~ two parts, a summer
{Phase I) and winter (Phase I!) program. This is principally due to field
logistics and the inability of transporting 1arge drilling equipment overland
4-2
I
I
J
I
I
·j
j
j
I
I
j
I I
I
I
I
1
I
1
~ ,f
I
'j
J
!
·~
.. · i
t
~ ! !
.:1
f~
l.l· J
' ' J
f~
.;
r~
j
~ Ji
f 'l
d i
)
t ~~
~ :
' ;l
1 ;~
j
I ,
1
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I ~· J
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1
}
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, a
until the winter. Therefore, the summer program will use smaller helicopter-
transported drill rigs that ~ill evaluate th~ upper 100-200 feet of the relict
channel. These rigs will be the same rigs used in the Borrow Area D investi-
gation (Section 3). Data from this program will be used in detailing the winter
programQ The objectives of the FY83 program are to:
(a) Phase I
Perform surficial mapping of the relict channel;
Define the surface and subsurface hydrologic regime in the upper 100-200
feet;
Obtain undisturbed and disturbed samples at depth to identify strati-
Hraphy and materia 1 properties;
-Install instrumentation for monitoring ground water and permafrost; and;
-Delineate extent of Fog Lakes Relict Channel.
(b) Phase II
-Confirm the geometry of the relict cham;el;
Obtain large bulk and undisturbed samples at depth for stratigraphic
delineation and material properties;
Evaluate the geohydrt logic regime where possible; and
-Install instrumentation for monitoring ground water and permafrost.
Phase I will i~volve drilling approximately 50 bori0gs distributed through-
out the Watana Relict Channel/Borrow Site D area and a limited geophysical
program (Table 4.2). Proposed boring locations are shown in Figures 4.2
and 4.3.
4-3
r:,
I j
I
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l i 1
1 l ,f I , ;
1
I
' j
___ J
'! ,j
The drill equipment will have capability of drilling a 6-inch sampler in
the upper 20-50 feet; reducing to 4-inch samples to 75 feet, anc subse-
quently reducing to standard 2-inch samples to full depth of 200 feet. The
intent is to obtain as large a diameter sample as possible to maximum
depth in order to determine the following conditions:
-Soil moisture content;
-Geohydrologic condition;
-Soi 1 density;
-Soil gradation;
-Stratigraphy and sedimentary origin;
-Permafrost conditions; and
-Obtaining sarr.ples for laboratory testing to determine plasticity limits,
compaction, permeability and dispersion potential.
The results of the summer investigations are expected to provide a model of
stratigraphy, ground water and permafrost regime~ and material properties
in the upper 100-200 feet of the relict channel for use in subsequent
design and estimates, and to assist in laying out the deep drilling program
to be performed in the winter program.
Phase II wi11 utilize the same large diameter hammer drill that was
described for Borrow SiteD (Section 3). Approximately 14 holes are
planned to penetrate to bedrock in the re"flct channel (Table 3.2). The
drill cuttings will be used in stratigraphic identification and borrow
materials testing. In addition, the drive and drilled sampling methods
utilized in Phase III will be used to obtain "undisturbed" samples for
laboratory tests. Proposed boring location for the hammer drill are shown
in Figures 4.3 through 4.5.
As in Borrow SiteD, emphasis in the sampling program will be placed on obtain-
ing maximum size samples for stratigraphic information and materials investiga-
tions. The various sampling methods that may be available are listed below.
(a) Fu 11 depth samp 1i rtt~ and lrJg.gi ng of dri 11 cutting, which wi 11 pro vi de
limited supplemental material and stratigraphic information.
4-4
. . .
~ ~
1
. l
i l
; i
.. 1
: !
(b) Drive and coring sampling, using 2-and 3-inch standard split spoon
samples, as well as special samplers such as the Denison.
(c) "Unoi sturbed" samp 1 i ng, using speci a 1 11 fl oati ng tube 11 or pi stan type
samples such as the 11
GUS
11 and "Osterberg" and various diameters of "Shelby 11
and similar split or solid thin wall tube sampling.
(d) Casing drive testing, using the hammer drill to ascertain relative varia-
tio~s in density.
(e) Water level detection and monitoring, both during and after drilling
operations .
(f) Installation of well casing screens and piezometers for subsequent observa-
tions and aquifer testing.
(g) Permafrost monitoring through drill cuttings temperature measurement,
observation of ice in the samples taken, and installation of frost probe
PVC pipe for continued observation. If significant frost is detected at
~
depth, full thermistor strings may be installed if thought to be
appropriate •
(h) Downhole geophysical logging, as appropriate, to provide correlation of
geologic interpretation between borings. Logging will be conducted in both
the hammer drill holes a11d the summer (Phase I) rotary larger borings
through 2-inch rvc pipe, which will be installed during drilling.
.~ ~--.
~;p,
:lfl'
* !'i~
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' ~ .. ;~Jl ..,, . ,,
( ;;·,
Jtl'·
h· 1~ I
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TABLE 4.1: FY83 EXPLORATORY PROGRAM
FOG LAKES RELICT CHANNEL
G(JPHYSICAL SURVEY
Seismic
Refraction Approximate Line No.* Location** Length (ft) Purpose
SL82-FL-A Channel A 22,000 Determine gradient of
channel.
SL82-FL-B Cha'lne1 B 15,400 Determine bedrock gradient
of channel.
SL82-FL-C Channel A and B 22,000 Width of Channel A and B.
Channel A 22,000 Determine bedrock gradient SL82-FL-D
of possible additional
channels.
SL82-FL-E Channel A 15,400 Upstream width of channel.
SL82-FL-F rhanne1 B 9,900 Width of channel.
SLB2-FL-G Channel B 5,5DO Width of channel.
*The seism1c lines shown here are based on
more complete definition of the channel~.
seismic linGs will be based on additional
results obtained during the program.
limited geologi~ dat~ suggested for
The number and orientations of
geologic mapping and interim field
**See Figure 4.1
I 1 ;,
1 ~
1 f' l
1 •
Seismic
Refraction
Line No.*
SLB2-A
Sl82-B
SL82-C
SL82-S
Or
Sl82-T
Sl82-U
SL82-V
Sl82-W
TABLE 4. 2: FY83 EXPLOR1\ TORY PROGRAM -PHASE I
WATANA RELICT CHANNEL GEOPHYSICAL SURVEY
Location**
Relict che:mnel
Relict channel
Relict channel
Relict channel
Relict channel
Relict channel
Borrow Site D and
relict channel
Relict channel
Approximate
Len9th ( ft) _
6,600
6,600
1 '100
6,600
6,600
1,500
1,100
3,500
Purpose
Bedrock depth, overburden
conditions.
Bedrock depth, overburden
conditions.
lie in lines SL81-14
and SLB0-2 to complete
coverage.
Detail of main relict
channel thalweg.
Same as above.
Tie in lines SL81-16 and
Sl81-15X to complete
coverage.
Tie in lines SL81-16 and
Sl81-18 to complete
coverage.
From SL81-13 to Tsusena
Creek to complete coverage.
*Seismic lines listed in order of priority, Sl82-D through Sl82-R on Te.ble 2.1. **See Figure 4.2.
~-
!,,
FOG LAKES
PROPOSED ;YB;r::LICT CHANNEL EXPLORATION PLAN
LEGEtm
GEOPHYSICAL SURVEYS· ~SEISMICR •
fl..
FL-1 TO EFRACTION SURVE ~B YUH
PROPOSED GEOPH YSICAL SU ~ SEISMIC RVEYS:
st.SZ• ARE REFRACTION .;
FL. A FIELttgE~~~~l~~~~~~~~~i/E~~~~E~;-INES
SCALE
0 ~1!!=~51 ,;;;;==;a='2 MILES
·: · .. -.,· ' •• •;" ... lo •••
H3,f3:tp90
~2~1
('
~~ ~~
"""'""''''•""'' ro'·"" """' ~'"""""'""'·'""" ''"'oo""'
0
L""'"'" "' !'loGE
[ ~ ~ ~ ~i ~I !I ;y
DETAILED OAMSITE SEISMI'VCINE
AND BORING lXPLORATIOH MAP
SHOWN ON FIGURE 2.1f /
~ (/ (/ /·.JaG-'::::::,
WATANA RELICT CHANNEL
PROPOSED FY83 EXPLORATION PLAN
~ ,..I ...
SCALE
0 1000 2000 FEET
~
.... 2400 ~
tl 2000 r 1.,.~
1200 [
1
150 _ AZIMUTH _
286
•
OF SECTION
l
HD·H
I
~~O~ECTED WfofECTED lOs•-AZIMUTH -315°
600' NE OM-A 200'SW l!D·C OF SE]CTION
<IOO'NE :MXJ'NE i I PROJECTED ~jECTEO
&~ I
NORMAL MAXIMUM r SW•3 SLB0•2 SL8V·I ' '"""""" . ,-~~:_:~~---~-=r"":i -t I j' r 'T -1 . ---------~-.,. __ ...,. __ _
f (LOOkiNG·DOWNSTRI".AM) -----------, \t"" ------v~~-~--------~·'"''"" -------
-------·---------= .. -·-------... , ~1500± ,----.. .; ________________ ,.
1,! THIS AREA APPROXIMATELY
9000' UPSTREAM OF WATANA
'rj-oo----OA-1.1 CENTERUNE
2400r
~ 2000r
§ ~· ~ 1600
ill
1200
0 [~ ·-·
NORMAL MAXIIolUM OPEf\:t!.TPIG
LEVEL E.L.21B:S
"i·--
.,. , -----..--. __ ...,.,.
TtllS AREA APPROXIMATELY
300D'UPSTREAM OF YIATANA
DAM CENTERUNE
HO-G
PROJECT£[!
400'NE
I
J SW-3
i
HO-E
PROJECTED
IOO'NE
I
OM-A
rNORMALMAXIMUM ~ l OPERATING POOL
' EDGE DR-20
-------"l!F~,
SLB0•2
i
DR·IB
i -----, .~
SUSITNA RIVER TO TSUSENA CREEK
ESTIMATED THALWEG ( DEEPEST PATH )
SECTION W-17
HD·D HO·A
PROJECTED PROJECTED
200'SW 200' NE
l I
SL B2·B SL BO•I
i i
"THE FINS" TO TSUSENA CREEK
SHORTEST FLOW PATH
SECTION W-16
WATANA RELICT CHANNEL PROFILES
135"~
I
2400
20DO
1600
1200
0 •100 BOO FEET
SCALE ~S5i~iiiiiiiu~·
I
135° ~l
r-TSUSENA CREEK n EL.I680
LEGEND
CONTAC'tS:
-----APPROXIMATE TOP OF ROCk
GEOPHYSICAL SURVEYS•
1200
fsw-1 INTERSECTION WITH SEISMIC REFRACTION
LINE
OM·C 1975, DAMES a MOORE
SW·I 1978, SHANNON a WILSON
SL SO· I 1960, WOODWARD· CLYDE CONSULTANTS
SL81·2 1981, WOOOWARO·CL:fDE CONSULJJINTS
BOREHOLES:
OR-19 COE ROTARY DRILL BORING
PROPOSED BOREHOLES:
HD·A HAMMER DRILL BORING
PROPOSED GEOPHYSICAL SURVEY•
tL B2·A SEISMIC llEFRACTION LINE
NOTES
I. PROFILE ANO SEISMIC I..INE LOCATIONS SHOWN ON
FIGURE 4.4.
2. SECnON ALONG OM·A SHOWN ON FIGURE 4.~.
3. VERTICAL AND HORIZONTAL SCALE EOU:t!.L.
4 SURFACE PROFILE FROM I"• 20d TOPOGRAPHY,
COE 1978 TOPOGRAPHY GENERAUZEO TO .±25 FEET.
:1. TOP OF ROCK NORTHWEST OF SL BO·I IS PROJECTED
UP TO 300 FEET TO PORTRAY ACTUAL THALWEG PROFILE.
6. AUGER BORINGS IN RELICT CHANNEL ARE SHOWN ON
FIGURE 4.2.
FIGURE 4.3
tf "" tl .... ..; "" 0 u. .q. "' -J ~ "" ~ n: :::J ~ c:: .. w 1-0:: iL i5 .. z z 3: 0: 0 :z: ;n 0 rn Ill w ID _J ,-J 0
-llcl(t~r..,.--
'1
l
t I I
' ® ~ ~ ~ •
"' .,; "" c:: :::1 .. iL z 0 t:i .., .... ~~ z ;!::. 0 ./! "' !:.: i 0 z g rn
&·no
J j ~
[gl ~ ~ w lr :::l (!) Li:
l
OJ 0
ell
< ~ l
L
I
I
L
1
ft$1\HitfM"'ilR I
l'
I
I
('~ ·;;::'
0
7:300
2200
~ w
... 2100 !:::
19()0
1800
1700
~~--------~-----------------
_045.-. AZIMUTH __,..-?25•
O" SECTION (""
AH-O/HO·I PROJECTED
700'NW
I
WATANA RELICT CHANNEL-EXPANDED THALWEG SECTION
·,
,#
2400
2300
2200
2100
2000
1900
1600
I roD
LEGEND
LITHOLOGY<
LZ1 c 0
IZill] . E,F ~ .
[I] G D
[.~'}~~ H ~a:,ttJ
CONTACTS•
KNOWN UNIT CONTACT
INFERRED UNIT BOUNDARY
X
J'
J
K
~~ BEDROCK SURFACE WHERE DRILLFD.
NORMAL MAXIMUM OPERATING LEVEL EL 2.185
BOREHOLESt
OR•26 COE ROTARY CORE BORINGS f:r NOTED AS FROZEN DURJNtt DRILLING
PROPOSED BOREHOlES:
HD·E HAMMER DRILL BORING
AH ·B AUGER BORING
NOTE
I. LOCATION OF~ oiii..CNG SC:t3W1C LII'IE DM-e,""l'!
FIGURE 4.4. ·
SCALE
C !10 _ 160 FEET VERTICAL
~
0 400 BOO FEET HORIZONTAL
SCALE r:= l
FIGURE 4.5
:.-
~r~
11 I
!
I ]·' l. !
{''
l! 'l \. ' bl
5 -BORROW SITES E and I
5.1 -Genera 1
Borrow Sites E and I include the Tsusena Creek outwash plain and Susitna River
floodplain from a point approximately 2-1/2 miles downstream from the Watana dam
site to a maximum distance of approximately 12 miles downstream (Figure 3.1).
This material has been identified as the most favorable source for concrete
aggregate, filter sand and gravel, and dam shell gravel r·equirernents totaling
approximately 40, million cubic yards. The information in these ereas, to date,
has been compiled from seismic refraction surveys, air photo interpretation, and
various test pits and shallow auger holes.
5.2 -Objectives
The overall objective of the Borrow Site E and I investigation is to obtain four
types of information needed for refinement of construction processing and costs
and material properties. These are:
(a) Borrow site configuration to include lateral and vertical extent of suit-
able materials and groundwater conditions. This information is needed to
define type and method of excavation and placement.
(b) Limits of reasonable excavation depth based on geologic constraints, strat-
ification of deposit, and inherent stability of the materials. These
limitations will have significant impact on the actual economically
recoverable reserves which, in turn, can be expected to int.Juence maximum
excavation depth, net excavation losses, and, consequently, equipment
selection and overall land requirements for adequate development.
(c) Material gradations, including both typical and local variations in the
material quality, which will influence production methods and requirements
and possible processing.
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(d) Suitability of the material for use in concrete, filters, and dam shells.
This information will be used in selection of the type of processing
requirements and optimization of placement utilization as determined by
cost.
The objectives of the FY83 program are to:
(a) Confirm the accuracy of previous seismic data and, therefore, borrow site
quantity and reserve calculations; and
(b) Determine material properties.
5.3 -Approach
The amount of work that can be done within the FY83 is limited by time and the
sampling equipment which wili be mobilized to the site. The large hammer drill,
which is planned for use in the relict channel and river areas (Sections 2
through 4), will be utilized to Jrill several confirmatory borings to maximum
practical excavation depth below river level in the primary source area of
Borrow Site E with thG ;ntent of verifying the seismic data and obtaining
samples for gradation~ ~nd laboratory testing (Figure 5.1 and Table 5.1). This
drilling program should: verify the general overall suitability of the source;
ascertain the approximate upper size limits and range of the gradation; provide
adequ~te samples for physical and durability suitability; and give an indicati~~
of variability of the deposit with depth.
Subsequent studies for final design investigaticns will determine the actual
mineable limits, extent of variation in materials, ground water elevation, and
the proces£ing that will be required for each of the major gr~dation variations.
The ~Y83 summer program in Borrow Sites E and I will be limited to completion of
surficial geologic mapping during Phase I to delineate all exposures of rock and
borrow materials with the intent of defining material limits and geomorphologic
features which may give indications of expected material properties~ It is
anticipated that the information obtained from the mapping will be limited to
identification of relict terraces, alluvial fan deposits, and river floodplain
limits with~n the borrow site. Phase II borehole locations will also be
established during the summer program.
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The \'linter program will involve use of the large hammer drill which will
continuously sample from ground surface to the maximum practical excavation
depth (which is estimated at 125 feet below water level). The drilling will be
distributed over the length of Borrow Site E to provide a general overall view
of the borrow materials. Due to the wide spacin9 of these borings~
stratigraphic correlat~on is not expected to result from this drilling. The
borings will be concentrated along the margins of the site to meet the criteria
below:
(a) Ready access and relatively level drill setup to minimize setup time and~
thereby, maximize the number of holes drilled.
(b) Placement of at least ten of the holes on previous seismic lines to verify
the seismic data interpretation •
(c) Placement of several holes along the active river margin to verify the
off-end-of-line seismic interpretation of alluvial depth and composition.
(d) Placement of a line of holes near the north 1imit of the floodplain to
confirm the average depth of alluvium and to assure that bedrock level do~s
not rise rapidly in the north and east portions of the borrow site.
(e) Spacing of the borings so as to maximize the information concerning the
variability of stratigraphic conditions within the borrow site.
Borenole sampling will be conducted as listed below:
(a) Primary sampling will be continuous cutti~gs sampling up to 4-inch size
particles.
(b) Split spoon or Denison/Core Barrel sampling, as necessary, to sample fine
sand, silt! or clay layers which may be encountered.
(c) Casing dive tests (open casing drive tests) for general correlation of
stratigraphy versus density for use in estimating excavation requirements.
Since the borrow site is planned for dragline excavation, detailed density
testing is not considered necessary at this time.
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(d) Wat~r table detection and monitoring to provide information on potential
dry versus wet excavation. Because the water table is expected to range
from 10-30 feet below ground surface, simple standpipe piezometric
monitoring will be utilized to allow continued monitoring of seasonal
variations of the water table.
(e) Frost detection wi 11 be limited to direct observation of drilling rate and
temperature measurements of cuttings. No permafrost is expected in the
borrow site; however, the depth of seasonal frost will be measured and
checks wi11 be made throughout drilling operations to record any indica-
tions of possible permafrost. If any permafrost is detected, thermal probe
standpipes will be installed in the appropriate zones to detect the extent
of the affected zone. In the remaining holes, standpipes will be installed
to approximately 30 feet deep for detection of annual frost penetration
thermal probe headings.
5-4
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' TABLE 5.1: FY83 EXPLORATORY PROGKAM -PHASE II
BORROW SITE E HAMMER DRILLING PROGRAM
.. '1
f Boring* Approxir--ate Approximate
Number Location** De2th (ft) Instrumentation*** Pur2ose
'-HD-A SW-10, south end 60 Define stratigraphy, check
on seismic line picks,
material sampling •
•• HD-ij SW-1 O, north end 125 SP FP Same as above.
1-'0-C SW-12, north end 110 SP FP Same as above.
'~ HO-C SW-12, center 75 SP Same as above.
HD-E SW-12, south end 125 FP Same as above.
HD-F SLB0-9 1 north end 125 SP FP Same as above.
• HD-G SLB0-9, center 110 S? FP Same as above.
HD-H SLB0-9, so•·:h end 120 FP Same as above.
• HO-I SL81-17 75 Same as above.
HD-J Si~-13, center 75 SP FP Same as above.
• HD-K SW-13, south end 175 Same as above.
HD-L SW-·13, north end 60 SP FP Same as above.
ff; HD-M On river bank 90 Same as above.
HO-N On river bank 70 Same above. ', ~--:-
as ,_
upstream of Tsusena
~' Creek
j HD-0 At intersection of 60 SP S:une as above.
SL80-11A & SLB0-118
vj· HO-P Upstream on Tsusena 100 SP Sam6 as above.
' Creek
TOTAL 1,555 SP = 9 in~tallations, -allov.J 1 miscellaneous
.t· installation •
FP = 8 installat:'ons, aU ow 2 miscellaneous
.. J instdltions.;
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"*Sor~ngs l2sted by priority~
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**See Figure 5.1. c
***SP = Standpipe piezometer.
"J FP = Fr.ost probe.
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PROPOSED FY83 E EXPLORATION PLAN
:.,:;
CONTACTS:
·--MATERIAL LIMITS "
BOREHOI ES "" • AND TEST PITS
,..AH·EI 1960 'AAI AUGER B
•TP-5 1978 DRING 'coe: BACK.-1 BTF-E3 OE TEST PJT
'IP•RI3 1981, AAI BACKHOE T EST PIT
GEOPHYSICAL SU
6!>-vt-12 SEISMIC R RVEYS•
TURNING o"if~~ION SURVEY
SW·12
1078
POINT
• • SHANNON a W.. ~
SL80•9 1980·81 tt..!LN 'WOOOWARD·ct.:
PROPOSED BORE :rt>E c·.~SULTANTS
•
HOLES:
HO•A HAMMER DRILL B'lRING
SCALE
FIGURE 5.1
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6 -LABORATORY TESTING
f. 6.1 -General
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The material testing program for FY83 will be designed for providing ready
assistance in data interpretation. To expedite the testing program, a field
laboratory will be established for performing rcutine soil tests to include:
-Gradation;
Hydrometer;
-Moisture;
Atterberg limits; and
Proctor.
The more sophisticated tests will be performed by outside laboratories as
required.
6.2 -Damsite
As discussed in Section 2~ petrographic analyses will be performed on specimens
of rock and sheared material obtained during geologic mapping activities. While
petrologic rock type identification in slab section will suffice for delineation
of the different rock types, full thin section petrographic analysis may be
required for samples taken in contact or shear zones. The greater detai 1 of the
thin section identification can provide valuable data concerning the emplacement
sequence and subsequent shearing and vein injection history, which will be of
significance in evaluation of anticipated alteration and rock strength at depth
in the pluton. The samples wi 11 be taken from outcrops and from core dr·i lling
to date, with an estimated 30 identifications and descriptions being performed.
During Phase II, approximately 20 holes averaging 100 feet deep~(60 feet of
overburden) are planned using a hammer drill. Limited spoon and barrel
sampling will be performed, but a majority of the sampling will be retrieval of
ai r-educted a 11 uvi urn through use of a eye 1 one separator. The estimated number
of samples and routine tests to be performed on these samples are shown in Table
7.1.
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More detailed tests to be performed on undisturbed and other material samples
will be undertaken following Phase II activities when an understanding of the
subsurface materials in the damsite has been determined.
6.3 -Relict Channels/Borrow Site D
The material properties in the relict channel are of significance to the geo-
logic understanding of the region as well as in evaluation of the long-term
stability of the area. The Fog Lakes Relict Channel geologic mapping may
produce a limited number of bagged samples of alluvial deposits collected from
face exposures, which can be submitted to standard sieve and hand specimen
descriptive analyses. No detailed material testing is planned for the FY83
period in the Fog Lakes Relict Channel.
The material testing program in the Watana Relict Channel will be conducted in
conjunction with the Borrow Site D testing. The principal objective of the
Phase I work is to identify and define the type and extent of stratigraphic
units in Borrow Site D and the relict channel. rnerefore, the soil. .. testing
progr·am during Phase I will be limited to routine tests as shown in Table 7.1.
Undisturbed and disturbed samples taken during this phase will be stored until
data interpretation has advanced to the level where a sophisticated material
testing program can be planned. However, th~ type of tests that may likely be
undertaken for the relict channel and Borrow Site D are:
(a) Relict Channel
-Permeability;
Consolidation;
-Di spersi on;
-Strength/density testing; and
-"In situ" triaxial strength.
(b) Borrow Site D
-Remolded permeability;
-Dispersion;
Triaxial strength on remolded material;
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-Dilation (dynamic);
f~ -Dynamic shear strength;
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Freez-thaw; and
-Thermal properties.
It is expected that the detailed testing program will be prepared after Prase I
activities.
6.4 -Borrow Sites E and I
Because this area is intended for use as concrete aggregate, filter, and shell
material, a number of tests may be run after the completion of the winter
program, as shown in Table 7.10 Since this borrow material will be processed,
it will not be necessary to test for in situ properties such as moisture,
strength, and density. However, extensive samples obtained during the drilling
program will be run for gradations. A few representative hydrometers will be
performed to provide typical data on settling times and water quality effects of
the fines in washing and processing operations. Other sophisticated laboratory
testing that may be run on compos·;te samples are:
-Sulphate-soundness;
-L.A. abrasion;
-Freeze-thaw;
Soundness (wetting-drying);
-Proctor compaction;
~ Density-strength testing; and
-Bulk permeability after washing.
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7 -RESULTS OF PHASE I INVESTIGATION
As previously specified, the majority of data reduction for the FY83 program
will be performed in the field. This will allow use of the data in seeping the
subsequent phases of studye The Phase I data wi 11 be used to update and refine
those geologic and geotechnical interpretations presented in the Feasibility
Report and the 1980-81 Geotechnical Report. As additional data become avail-
able, add,enda to these reports reflecting these new data will be prepared as
required. Finalization of these addenda are expected to be completed in
November-December 1982.
7-1
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TABLE 7.1: ESTIMATED FV83 FIELD LABORATORY TESTING
Source
No. of l.irab Sample Sample Type Test.1ng Reta1n for
Holes Gradation Ur1Ve/Core Cyclone Gradat10n Hydrometer Moisture Atterberq Proctor Future Testing
.Ser1e:;
(Modified
Summer 1982: & Stan-
dard)
Fog Lakes
Relict Channel 0 15 0 0 15 15 5 5 0 15
Watana Relict
Channel 24 10 BOO 0 200 50 50 50 0 100
&
Borrow Site 26 20 850 0 200 100 100 100 5 100
Wi!"'lter 1982-83;
Damsite River
I Alluv iuu 20 -100 220 200 20 0 20 5 50
Watana Relict
Channel 9 0 200 300 150 25 50 50 5 100
&
Borrow Site D 5 0 150 300 150 25 150 150 20 100
Borrow Site E
and I 16 0 300 200 2f 0 20 20 20 150
TOTAL
(13,850 LF of
drilling) 100 45 2,200 1,120 1,015 255 355 395 55 615
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8 -PROJECT SCHEDULE
Figure 8.1 is the proposed schedule for FY83 Geotechnical Program. Key mile-
stone dates to ensure performance of the work specified in Sections 2 through 5
~re the mobilization of drilling equipment and personnel for Phase I into the
field by July 6. Similarly, the mobilization of the hammer drill overland dur-
ing December will be critical to allow for drilling in the relict channel and
dam foundm:i on. Thererore, to accomplish th·i s, a contract for Phase I work must
be in pla1:e by the second to the third week of June. The contract for the
hammer drill must be let by September to allow adequate time for mobilization of
the eq~ipment to the site.
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TASK
I
2
3
4
5
6
7
8
DESCRIPTION
l CONTRACTS
l PHASE I l
DRILLING
SEISMIC REFRACTION SURVEY
PHASEll
I DRILUNG
I SEISMIC REFRACTION SURVEY
PHASE m --WATANA RELICT CHANNEL I GEOLOGIC MAPPING
AUGER DRILLING B INSTRUMENTATION l
HAMMER DRILLING a INSTRUMENTATION
SEISMIC REmACTION SURVEY
, BORROW SITE D
I ' GEOLOGIC MAPPING I
! AUGER DR:LUNG 8 INSTRUMENTATION
I HAMMER DRILUNG B INSTRUMENTATION
MAIN DAM SITE
GEOLOGIC MAPPING
LOCATE SURVEY CONTROL POINTS
CIVIL STRUCTURES
GEOLOGIC STnUCTURES
HAMMER DRILLING {RIVER BED)
CORE BORINGS (ABUTMENTS)
SEISMIC REFRACTION SURVEY I FOG LAKES RELICT CHANNEL
GEOLOGIC MAPPING
i SEISMIC REFRACTION SURVEY
1 BORROW SITE E
HAMMER DRILLING a INSTHUMENTATION
SURVEY CONTROL
SET UP MAPPING GRID POINTS
LOCATE SEISMIC LINES
I LOCATE DRILLHOLES
SUPPLEMENTAL REPORTS
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-FY82
PHASE I .
APR J MAY I JUN JUL J AUG J SEP I OCT I NOV I
0 2 4 6 8 10 12 14 16 IS 20 22
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SCvPE 610 DOCl.II.!E>m;. BlD rAW~OB DR U.ING
lllllllliJIIII ~-I NOTIC~ TO BICkR;,.,""'"\ OUAt NEGO~ f AW MDB SURVEY -.
I l.. .. .J.m'l.l.. ... J... ... I ! Blt DOCUMENTS BID • AW I NOTICE TO BIDDERS 7
f I I l I I l ! OUAL -.-I I I
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GEOTECHNICAL SCHEDULE
TASK 55 FY83
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--·
FY83 ----·-·---· '""'"'
I PHASE Jr I PHASE Jli
I DEC JAN I FEB I MAR I APR MAY JUN
24 26 28 30 32 34 36 38 40 42 44 46 48 50
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DRILLING ....
NEGOT A, MOB SUR \lEY ,..., I
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FIGURE 8.1 [iJ