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SUSITNA HYDROELECTRIC PROJECT
FY83 PROPOSED GE01ECHNICAL
EXPLORATORY PROGRAM .
DRAFT
MAY 1982
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ALASKA PO\tlER AUTHORITY
SUSITNA HYDROELECTRIC: PROJECT
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FYB3 PROPOSED GEOTECHNICAL EXPLORA70RY PROGRAM
TABLE OF CONTENTS
Page
I LIST OF TABLES
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LIST OF FIGURES
1 -INTRODUCTION . . . . . . . . . . . . . . . . . . ~ . ~ . -. . . . . . . . . . . . . . . . . . -. . . . . . ~ . 1
2 -DAMSITE IN.VESTI GA TION ••••••• , • $ ........... ~. • • • • • • • • • • • • • • • • • • 3
3 -
2 .. 1-G-eneral.-......................................................... 3:
2.2 -Civil Structu·res ... · ............................... ,. . . . . . ... . . . 3
.2.3-Geologic Structures ....•.......... ~..................... 7
2 .. 4 -Miscellaneous Investigations . . . • . . . . . . . . . . . . . . . . . .. . . . . .. . 13
BORROW ·sITE D ....................... '> ............................... · ... ..
3 .. 1 -Genera 1 ..................... ., ....... ~ ..... -· ..... ~ ................ ._
3.-2 ~Objectives .. .::;;. ....... ·······~-··-···~···c-···················-~· 3.3 -Approach ..................... ~ ... _..,. ........... , .................. .
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15.
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4 -RELICT CHANNEL ......... ·· ................ : . . . . . . . . . . . . . . . . . .. . . . . . . . . . 19
4. 1 -Genera,. . ..... "' . • • .. . .. . . . . . . .. . .. .. .. . . . . . . . . . . . .. . . . . . . . . . . . . .. . . 19
4.2-Obj~ctives ······················~······················~ 19
4.3-Approach/Discussion ...................... e ....... ~-······ 20
5-BORROW SITES E AND I •••• ~ ••••••••••••.•••••••.•..••••••••••••• 24
5· .1 -Genera 1 ..................... "!-;., .................... __ .• • • • • • • • • • 24
5.2 ..-Objectives . ~ ........................ -., ....... a. .•• *;...................... 24
5.3-Apprcach/Oiscussion ·········:··························· 25
6 -LABORATORY TESTING . ~ . . . . . . . . . . . . . ~ . ~ . . . . . . . . . . . . . . . . . . . ~ . . . . . . 28
7 -RESULTS OF PHASE I INVESTIGATION • .. • • • • • • • • • • • • • • • • • • • • • • • . • • • • 31
8-PROJECT SCHEDULE ...••.••................•.............. ~ ..•... 32
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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
9.1
9.2
TITLE
Watana Damsite Ge'J.Jtlys'ical Survey
Pha~'e 1
Watana Darnsite Geopnystcal Survey
Phase II
Watana Damsite
Hammer Drilling Program
Watana Relict Channel/Borrow Site D
Auger Dri't ~ ing Program
Watana Relict Channel /Borro.w. Site 0
Hammer Drilling Program
Fog Lakes Re 1 i ct Channe 1
Geophysical Survey
Watana Relict Channel
Geophysical Survey
Borrow Site E
Hammer Drilling Program
Estimated FY83 Field Laboratory Testi·ng
Subcontract and Squiprr:ant Costs
Phase I
Subcontract and Equipment Costs
Phase II
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LIST OF FIGURES
NUMBER TITLE
2.1 Watana .Damsite
Proposed FY83 Exploration Plan
'2 .2 Watana Damsite
Geologic Map
3 .. 1 WatanaBorrow Site Map
3 .. 2 Borrow Site D ·'
_ ~rpposed FY83 Exploration Plan
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4.1 Fog Lakes Re 1 i ct Channe 1
Proposed FY83 Exploration Plan
4.2 Watana Relict Channel
Proposed FV83 Exploration Plan
4.3 Watana Re1 i ct Channel Profiles
4 .. 4 Watana Relict Channel
Proposed FY83 Hammer'Drill Borings
4.5 Watana Re 1 i ct Channe 1
Expanded Thalweg Section
5.1 Borrow Site E
Propo:~d FY83 Exploration Plan
8.1 Geotechnical Schedule
Task V FY83
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1 -INTROOUCTON
T~is. eport details the proposed FY83 (July 1, 1982 through June 30, 1983) Task
5 ueotechnical program for ~he Susitna project. The scope of the project is
based on Acres• and others• previous work at the sites, as well as directives
set forth by the Power Authority•s and Acres• consu1tants review panel.. The
level of effort for the FY83 is mandated by scheduling and logistic constraint
and budget. Because the Watana s·ite will be the first site developed, all FY83
activities will'be directed toward that site.
The FY83 field program will be perform~u in three phases.. Phase I will commence
on July 1 and continue through September 3u; Phase II wi 11 begin in December -
January and continue through March -April; and Phase III will commence in May-
June and continue through the end of fiscal yeat',. Subsequent phases of study
will be a continuance of Phase III activities.
This report is intendeu to provide a clear understanding of the. scope~ objec-
tive, methodology of approach, schedule, and costs for the FY83 activities.. It
is not the intent of this report to "cast-in-concrete" the proposed field activ-
ities, but rather· to set forth general guidelines to be followed. To expedite
t~1e project, all field data will be reduced and interpreted in the field. This
wiil assist the field personnel in seeping and revising the field studies as
required to meet the objectives of the project.
Work performed during Phase I will be used· in detailing the subs·equent phases of
work. The four principal areas that will be investigated during rY83 are:
-Relict Channels;
-Borrow Are"J. D;
-Borrow Areas 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 detflil the scope, cost, and sche<:iule for Phase
I and II activities·. The scope of Phase III will be dependent on infvrmation
obtained in Phases I and II, as well as bt!dgetary constraints.
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~ -OAMSITE INVESTIGATION
2.1 -General.
The FY83 damsite investigation will be a continuation of the previous investi-
gation performed during 1980-81 programs. The pr·incipal objectives are to:
-CQnfirm geologic mapping and interpretations previously performed onsite;
-Determine depth of river alluvium beneath the proposed mai_n dam and cofferdam;
and
-Determine rock condition in areas of proposed major civil structures.
The damsite invest·igation will consi!;t of geologic mappin9' during ?hase I; seis-
. mic refraction during Phase I and II; subsurface drilling during Phase II and
III. Details of the damsite exploration plans are shown in Figut"'e 2.1 and des-
cribed on Tables 2.1 through 2 .. 3. A schedule o'f fie"'.d acti'litie·~ is contained
in Section 8 ..
2.2 -Civil Structures
(a) Main D~n and Cofferdam Riverbed Foundations
(i} Objectives
The objectives of this investigation will be to C(lmplete e;xplora-
tions for riverbed foundation conditions for coff•erdams and main
dam. Explorations will examine both alluvial and bedrock conditions
beneath the river and on the adjacent abutments.. Data from this
task will be used in developing the general arrangement and design
of the cofferdams.
(ii) Discussion and Approach
The alluvial deposits of the Susitna River consist of gravel,
cobbles, and boulders \\fith a sand matrix-The thickness and type of ,
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material, as well as bedrock conditions, is known at only several
locations. Deve1opme·nt of the general arrangement and design of
cofferdams and the main dam will require deta.iled data on the fol--
lowing: thickness and types of alluvial material, frozen layers,
top of bedrock surface~ bedrock lithology and structure, and depth
to sound rock. The FY83 investigation to obtain this information
will consist of geologic mapping, geop~ysical explorati~ons, and
drilling. Geologic mapping, which will be performed during Phase I,
will consist of two parts: first, examination of t~~~ geology in the
imnt:diate area of the_proposed cofferdam locations; and, second,
mapping of geologic structures on the abutme~ts which may affect dam
and cofferdam locations and design .. The latter work will be dis-
cussed i~ca subsequent Section. ~eologic mapping of the cofferdam
sites will ~onsist of examining alluvial and bedrock conditions in
the immec;liate area of the planned locations.
During the winter .. a seismic refraction survey on the frozen river
surface will be performed. The surveys will run from "The Fins 11 to
downstream of the "F.ingerbuster 11 to define the top of bedrock sur-
face and alluvial thickness. The seismic lines will be arranged in
a grid pattern parallel to the cofferdam axis and along the, center
of the river (Figure 2.1 and Table 2.2J. Results of i..i1is survey
will be the basis for selecting river borehole locations. Boreholes
will be drilled during the winter from the surface of the frozen
. river to confirm the seismic line data and to sample alluvitn and
bedrock. A 11 Becker" type rig, capable of drilling 400•600 feet deep .
in alluvial material,will be used fa~ the drilling and sampling.
Drilling will consist of both plug holes and sampled holes (Table
2o3). Plug holes will be drilled to confinn fluvial thickness and
depth to sound bedrock. 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. A minimum of two of the holes beneath the core of the
proposed dam will be core dri 11ed to a depth of 50-100 feet and
pressure tested to. determine rock permeability.
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(iii} Sch~dule
Geologic mapping for __ the: cofferdam locations will be done by a team
of two geol{)gists. Because of the priority,-this mapping will be
done at tt\e onset of the field season in Phase I. During the winter
. when ice conditions on the river are suitable, approximately 9,000
feet of seismic 1 ines ~ti 11 be run a 1 ong the axis of the river and an
additional 4,000 1 inear feet in the cofferdam areas (Table 2.2).
Drilling of the river a1luvilJ1l will commence after completion of the
~eismic 1 ines. .A total of 5 dril'~ hole:s are planned for each cof-
ferdam site: two sample holes and three plug holes. Total dr~1·1
footage for the cofferdam sites is estimated to be 1,000 fu=t. An
additional 5 drill holes will be dt'"illed ben~ath the proposed main
dam ..
(b) Portals
Portals include the .upst·ream aiversion tunnel portals and downstream diver-
sion, spillway, access, and tailrace tunnel portals •
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(i) Objectives
The objectives of the portal investigation will be to complete ex-
plorations for portal ·locations~ orientations, and support require-
ments for upstream and downstream portals. E;·plorations will
examine and define overburden materials and bedrock conditions.
(ii) Discussion and Approach
The primary geologic structures which may have an affect on the up-
stream and downstream portal design are the geologic structures re-
ferred to as 11 The Fins" and the uFingerbusteru, r-espectively Figure
2.2). These features will be the main focus of data gathering.
Both areas are characterized by northwest and north trending shea,r 9
fracture, and alteration zones. Bedrock is well exposed in ''The
Fins11 in a series of cliff faces. Outcrops ure not as common in the
uFingerbusteru where talus covers much of the area.
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The investigation will ~xamine and describe the type ana thickness
of overburden material, bedrock lithology and structure, depth to
sound bedrocks rock permeability~ ground water table, and areas of
potentfal slope instability.. Explorations for the portals will con-
sist of geologic mapping, seismic refraction surveys, and drilling.
Explorations will be more detailed and concentrated than during pre-
vious investigations.. Ge~logic mapping will precede other forms of
exploration in the summer of FY83, and will form the basis for
locating sei.smic lines and drill holes. Geologic mapping will con-
sist 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 instability. For the upstream portal,
mapping will be done in an area approximately 500 feet upstream and
downstreamfrom the proposed portal locations ana between river
level and elevai;ion 1,800 feet.. Mapping for the downstream portals
will cover an area from the toe of the proposed dam to the 11 Finger-
buster11 s';lear zone, approximately 1,500 feet, and between river
level and elevation 2,0UU feet (Figure 2.2}. Data from the mapping
will be.plotted on maps and sections of suitable seal& . .md on joint
stereo plots. This data will be in'terpreted and used for furthe}C'
explorations and design requirements.
A seismic refraction sw .. vey will be run in the downstream portal
area ~o define ov-erburden thickness structures, and depth to sound
bedruck. Seismic 1 ines \'li 11 be r•un in a grid pattern based on the
results of geologic mapping (Figur.e 2.1).. An estimated 4,500 feet
of seismic lines wil.l be run. A ltOOO-foot seismic line is planned
at this time for the upstream portal. This line will be run on the
frozen river surface immediately offshore of 11 The Fins 11 structure.
Boreholes will be drilled in both portal areas .to determine type and
thickness of overburden materi.al, subsurface geologic conditions,
rock permeability and ·ground water conditions.. Drilling will con-
sist of approximately 6 to 10 pr.edominant1y angled boreholes to
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various depths during Phase III .. Total drill footage is estimated
at 2,000 linear feet. Bedrock will be continuously cored using
NQ .. ·size core barrels. Core samples will be logged for 1 fthology and
structure. Selected samples will be tested for unconfined compres-
sive strength using a point load tester. Following completion of
the drilling, joint and fracture orientations at depth will be
determined using a borehole camera. Water pressure testing wi 11 be
done over the length of the borehole to determine rock permeability.
One borehole in the upstream portal area and two boreholes in the
dow~1stream portal area wi 11 be instrument.ed with piezometers for
gro_und water monitoring.
(iii) SchedulE?/
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. Oiamond core drilling will be done during Phase III.
2.3 -Geologic Structur~~
(a) Shear, Fracture, and Alteration Zones
Shear, fracture, and alteration zones are the northwest and north trending
geologic features identified. during the 1980-81 explorations. This aspect
9f the exploration does not include 11 The F)nsn, "Fingerbuster 11 , and-geo-
logie features GF7 and GF8 which will be investigated during subsequent
phases of exploration Figure 2.2)(1).
(i) Objectives
The objectives of the geologic structure investigation is to provide
adequate geological and geotechnicar information needed for develop-
ing the general arrangements. Explorations will be directed to
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determining the nature and extent of these geologic features at .
depth.
(ii) Discussion
Northwest and north trending geologic structures which include
shear, frar.ture, .and alteration zones were identified during pre-
vio~s inve~tigations(l}. These features were tentatively
correlatea across the site on the surface and to depth in boreholes.
The FY83 investigation will attempt to confirm thes? geologic
interpretation.
Principal attention will be directed to the right abutment where the
majority of c iv·i 1 structures are tentatively proposed.
·Areas requiring further investigation are geologic features C:iF2,
GF3, and GF4, which were defined in the 1980-81 program as potenti-
ally projecting into the proposed powerhouse intak~ area (Figure
2.2).
~roach
Explorations for the northwest and north trending geologic struc-
tures will consist initially of geologic mapping and seismic refrac-
tion SL'lrveys followed by aiamcnd core drilling. Geologic mapping
w i 11 py·ecede other forms of exp 1 oration and wi 11 be the basis for
•' locating seismic lines and boreholes. ueologic mapping will consist
of identify~r.~ and describing the following: type of geologic
struc-1,ure, orient at ion and extent, degree of weathering or a ltera-
tion and joint sets, and spacing. Geologic data will be plotted on· . .
ma.ps and sections at a suitable scale. This data will be inter-
preted in the field and used as the basis for planning future ex-
plorations. Mapping will consist primarily 9f traversing along the
extent of the structures and accurately locating its position.
Cross traverses wi 11 be run across. the abutments, as necessary • ..
Most of the traverses will be done on the right abutment between
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11 The Fins" and 11 Fingerbuster" shear zones from river level to eleva-
tion 2,300 feet. On the left abutment, mapping will extend from
geologic featut .. e GFlB to GF6B and from river level to elevation
2,000 feet {Figure 2.1).
Se.ismic refraction lines will be run on both abutments to define the
.~acation of low velocity zones related tq shear, fracture, and al-
teration zones as well as thickness of overburden materials, and
depth to sound bedrock {Figure ~~1). On the right abutment~ one
seismic line will be run from "The Fins" area parallel to the slop1a
at about elevation 1,800 feet to the uFingerbuster" shear zone.
This line will cross the entire abutment and all major geologic
structures. An additional seismic line at approximately elevation
2,050 feet w·ill connect seismic lines SL81-15 and SW-2 to complete
coverage at this elevation. An estimated 6,000 linear feet of
seismic ·1 ines wi 11 be run on this .abutment. On the left abutment,
one seismic line will be run eastward from the end of SL8l-i!O
between· elevation 2,000 and 2,050 feet. This 1 ine will help define
the extent of geologic features-in GF3 and GF4. Lin~ lengt.h is
approximately 2,00G linear feet. Seismic velocities will be plotted
on maps and sections at the same scale as geologic data.
Correlations 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.
will be drilled across various geo·logic structures to, verify their
presence and define their subsurface characteristics. Data will in-
clude joint spacing and, where possible, orientation, rock permea-
bility and strength 9 and ground water conditions. Ol'·illing will
consist of approximately 10 angled boreholes to an a\rerage depth of
500 feet. Locations of these borings will be based on Phase I and
II activities. Boreholes will be drilled on both abutments and
beneath the river. Bedrock will be continuously cored using NQ--size
wirelfne core barrels. Core samples wiJl be logged for lithology
and structure. Se 1 ected samples will be tested for unconfined
compressive strength using a point load te•. er .. Following
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completion, fracture and joint orientation at depth will be deter-
mined using a borehole camera~ Water pressure testing will be done
over the length of the borehole to determine rock permeability.
Selected boreholes will be instrumented with piezometers for ground
water monitoring •
(iv) Schedule
Geologic mapping wfll begin following portal area mapping. One
two-man team of geologists will b~ used for mapping on the abutments
D·iamond core drilling will be done during Plase III following com-
pletion of p~rtal area drilling.
(b) Pluton Structure
(i) Objectives
The object-ive of this investigation is to establish the geologic
model for the· damsite area and quarry sources for· general site.
arrangements. Explorations will examine and define the extent of
the diorite pluton, the nature of its contacts with adjacent rock
types, and its structural relationships\1).
(ii) Discussion
The Watana dc..rnsite is underlain by a diorite pluton which has
intruded .into surrounding metasedimentary. West oft.he 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 generally fractured with minor, _local shearing.
The andesite porphyry immediately above the contact is generally
highly fractured, however, the underlying diorite is generally
'Jnfractured. The eastern boundary of the pluton has been .proje~ted
to cross tnrough the reservoir area east of the damsite; however,
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this contact has not been adequately defined. The pluton is
crosscut by shear, fracture, and alteration zones.. The origin of
these zones, whether due to regional tectonic forces, local pluton
re 1 ated forces, or a combi nati o·n of the two, has. not been deter-
mined.
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 ttle damsite area. The geologic model, can be used to predict the
nature and extent of various lithologies and structures where scarce
data exists.
(iii) Approach
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
awe-y 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 proposed Quarry A, and any other suitable
locations ba!;ed on aerial reconnaissance.. Geologic mapping for this
investigation will not require the level of detail or control as
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that done for the porta 1 s, coffe~dams or shear, fracture, and .alter-
ation zones. Detail airphoto interpretation will be done prior to
mapping to identify locations to be mapped ..
. In addition, detai 1 petrographi cs studies wi 11 be performed on vari-
ous rock types collected during the mapping program to determine
mineralogy, lithology, and the sequence of geologic events.
Geologic mapping for p 1 uton structur~s wfll require a team of two
geologists during Phase I.
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(c) "The Fins" and ~Fingerbuster"
·{i) Obj~c~1ves
The. objective of this investigation is to complete explorations of
these geologic features for general arrangements and design of un-
derground civil structures. Expl or· at ions wi 11 examine and define
the surface and subsurface nature and-extent of these features.
(ii) Discussion and Approach
"The Fi ns 11 and 11 Fi ngerbuster 11 bound the d.ams ite on the upstream and
downstream sides, respectively (Figure 2.2). Both features contain
major northwest and north trenaing shears, fractures, and alteration
zones which would have a. significant 'Qlpact on cost3 for any civil
structures 1 ocate.~d within them. At present, these structures have
been identified o.'l the right abutment and tentatively projected,
based on correlation with boreholes, seismic data, and topography.,
This investigation will attempt to confirm these correlations and
de.fine and describe, in detail, the surface and subsurface charac-
teristics of these feat"'···;s. Explorations will consist initially of
geologic mapping followed by seismic refraction surveys and diamond
corE! drilling. Geologic mapping will be the basis for locacting
seismic lines and boreholeso Mapping will consist of identifying
and describing the follrywin~: type of geologic structure, orienta-
tion 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 wi'J'l be interpreted in the
field for use in planning further explorations.. ~eolvgic mapping
will consist of tracing the extent of these features by ground trav-
erses and aerial reconnaissance. Mapping on the north bank will
extend from the Susitna River to Tsusena Creek. On the south bank,
limited outcrops will restrict mapping to within about one mile uf
the river.
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Seismic refraction line.s wi 11 be run in both urhe Fins" and 11Finger-
buster11 areas to define the extent of low seismic velocity zones re-
lated to these features, thickness of overourdenj and depth to sauna
bedrock •. The amount and location of seismic lines is dependent on
the results of geologic mapping. An estim~ted 8,000 linear feet for
UThe Fins it and 4,000 1 inear feet for the 11 Fingerbuster 11 are p 1 anned
(Figure 2.1} •.
Geolog·lc mapping of "The Fins 11 and "Fingerbuster" is planned dvring
Phase I ·with two geologists forming a team.
2.4 -Miscellane-ous I~tvBstigations
{a) Instrumentation of Existing Boreholes
(i) Objectives
The objective of this exploration is to gain additional aata on
ground water and permafrost conditions in the bedrock at the main
damsite f--1 design and construction activities.
(ii) Discussion and Approach
To complete the instrumentation progr.am at .. ne damsite requi.res
-additional piezometers and thermistors to be installed. At present,
thermistors are located on the right abutment in BH-3 and BH-6. It
is proposed that a thermistor string be installed in BH-8 (dr·illed
in 1981} to.evaluate permafrost conditions on tne left abutment.
Thermistor construction would be the same as. the existing units with
16 thermistor points along a 250 foot cable.
Two piezometer i.nstallations are -proposed for special conditions in
Boreholes &H-4 and BH-12.. A }lneum~+,ic piezometer tip will be in-
stalled at the elevation of the powerhouse in BH-4 to determine
. ;
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·,..-:" ..• ~ (iii)
water pressure conditions.. at this depth. In BH-12, a prieumatic
piezometer tip will be installed be.low the artesian aquifier at .
about 400 feet.
To insta1.1 the piezometers and thermistors, boreholes BH-4, BH-8,
.and BH-12 wi 11 have to be reamed out to the required d~pths to a1ruw
placement. Approximately 1,600 feet of reaming will be required •
Scher)ule
This work will be undertaken during Phase III. I
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(b) Survey Control
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{l} Objective
The objective of survey control is to establish adequate ground
control for use in damsite investigations.
(ii) Approach
Upon conmencing work in July, a survey grid will be established on
both abutments and along the river for ground contra 1. The grid .
will be on an average of 500 foJt spacing. with permanent markers
estab'lished at designed.locations~ The grid will be tied_ into the
State of Alaska grid ~ystem.
All fie_ld e!{ploration performed on the damsite wi l'f be controlled by
the surveyed grid ..
(iii) Schedule
Work on estab li shi ng the grid wi 11 be undertaken in the early part
of Phase 1 •
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,... .---.,
Seismic
Refraction
Lin~ No.*
5LB2-D
SL82.;..(
SL82-F
SL82-G
SL82-H
SLB2-I
(}
SLAZ-J
SLBZ-Ka
SLSZ-Kb
SL824.
SLB2-M
SLBZ.;.N
SLBZ-0
SLB2-P
SLB2-Q
SLB2•R
TABLE 2.1: fYB3 EXPLORATO'Kl' PRObiiAM-PHA~E 1
WATANA DAMSITE GEOPHYSICAL SURVEY
Location**
Downstream Portals~
BH-6 towards BH-2
Do~.stream Portals,
OM-\; to SW1
Downstream Portals,
SW.,.2 t.o river
Flip Bucket
Downstream Pf'Jrtals,
mid elope
DH-9 to SL80-Z
Spillway
Right Abutment
~stream Right Abutment.
Powerhouse Aree.
Upstream Left Abutment
Right Abutment, SL81-15
to SW-2
Right Abutment
Upstream Left Abutment
Left Abutment, Downst.re~
Portal Area
Left Abutment, Downatream
Portal Area
TOTAL
Approximate
Leng!:h (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
1,100
26,600.
Purpose
Depth to bedrock, overburden thickness ..
Overburden thickness, bedrock ·conditions.
C!verburden thickness, bedrock conditions.
Overburden thickness, bttdrock conditions
in "Fingerbuster".
Overburden thickness, bedrock conditi~r~t NW and N shears.
Overburden thickness, bedrock conditions,
NW and N shears.. ·
O';erburden thickness, bedrock conditions.11 NW and N shea1."s. ·
Overburden thickness, bedrock conditions,.
NW and N shl!ars.
•·The fins," NW and N shears.
"The Fins," NW and N shears.
NW and N shears.
NW and N shears.
"'fhe Fins,n and possible east-trending
structures.
"The Fins" ..
"fingerbuster".
nringerbuster".
*Seismic lines listed in o~der of priority, seismic lines Sl.B2-A through C are listed on Table ..
**See Figur~ 2.1.
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TABLE 2 .. 2.: FY83 EXPLORATORY PROGRA~1 -PHASE II
WATANA DAMSITE GEO('HYSICAL SURVEY
Purpose
Depth of overburden and bedrock conditions.
Depth of overburden, bedrock conditions,
and "The Fins".
Depth of overburden and bedrock conditions.
Depth of overburden, bedrock conditions,
and "Fingerbuster".
Depth of overburden, bedrock conditions,
and "Fingerbuster".
Depth of overburden, bedrock conditions,
and "Fingerbuster".
Depth of overburden, bedrock conditions,
afld "The Fins'' ..
Depth or overburden, bedrock conditions,
and NW and N shears.
Depth of overburden and bedrock cnnditiona.
Depth of ovarburden and bedrock conditions ..
Depth of overburden and bedrock eonditions.
Depth of overburden, bedrock coOOitions,
end "f'ingerbuater".
Depth of overburden, bedrock conditiP.ns,
and ''f' ingerbuster" o
Depth of overburden, bedrock conditions,
and "f'ingerbuster".
Depth of overburdet~, bedrock cnnditions.t
and "f'ingerbuster".
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Drill Hole*
NUI\'ber
Qestresm CofferdBf!
HD-AA
HD-88
HD-CC
H0-0.1>
Main-Dam
HD-EE
HD-F'F'
HD-GG
Dollltlstream Cofferdam
HD-HH
HD-II
HL'-JJ
HD-I<K.
Upstream Portals
HD-LL
HD-t+t
HO..NN
Main Dam
HD-00
HD-PP
HD...QQ
HD-RR
TABLE 2.3: FY83 EXPLORATORY PROGRAM
WATANA DAHSITE HAtftR DRILLING PlJGRAM
Location**
Approximate oe 2th(ft)***
SLB1-4
SLSJ-88
SL81-5
SL8:3-AA and SLBJ-88 .
Centerline Sl8J-CC
Centerline SL83-CC
and SL83-HH
Centerline SL83-CC
SL83-DD
SLBJ-FF
SLBJ-fF
SL83-£E and SLSJ-00
SL83~G
SL83-GG
SLBJ .... BB
Upstream Toe,
SL83-HH and SL83-II
SL83-JJ
and SL83-HH
SL81-16
Downstream Toe,
SL83-HH and SLB3.:II
110
120
90
100
85
130
95
110
95
i'5
80
70
70
100
100
1.30
100
130
Sampling
Al.iUVillll
and rock
Alluvillft
and rock
Alluvillll
Alluviun
Alluviw
Alluviun
and rock
Alluvit.m
Alluvium
and rock
Alluvitlll
Alluviun
and rock
Alluvitm
Alluviun
Alluviun
Alluviun
Alluviun
Alluviun
and :tack
Alluviun
Alluviun
and rock
. Purpose
Overburden material and "
thickness, bedrock surface,
lithology and ?tructure.
Same as abovef'
Overburden material snd
thickness.
Same as above.
Same as above.
Overburden material and
thickn~ss; bedrock surface,
lithology and structure.
Overburden material and
tJ,ticknees.
Overburden material .md
thickness; bedrock surface,
lithology, andstructure.
3\/erburden materiBl and
thickness.
Overburden material and
thickness; bedrock surface,
lithology, and str'Qeture-.
Overburden material and
thickness.
Same as above.
. Same as above.
Same as above.
0-,..erburden material and
thickness; bedrCJtk surface,
lithology and structure. ..
Overburden materiti. and
thicknea.s. ·
Overburden material and
thickness;. bedrock surface,
lithology and atruct.ure.
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TABLE 2.3 (Cont'd)
Drill Hole*
Number
Plunge Pool
HO-SS
Location**
SL834*4 and
SLB}-00
TOTAL
*Bo·.rings ·listed by priority.
**See figure 2o1
Approximate
Depth ( ft )*** ·
90
90 -
1,970
Sampling_
Alluvium
Alluviun
and rock
Purpose
Overburden material and
thickness.
Overburden material and
thickness; bedrock surface,
lithology. and str.ucture.
***Assll'lle 10 feet of rock drilliny except 40 feet where rock will be sampled.
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+
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LEGEND
BOREHOLES AND TEST PITS:
(.:} Oli-1 IS78,COE 1DtAMOND CORE BORlNG,HOiTI:Z:ONTAL ·~ fPROJECTIONS AS SHOWN
BIN~ 19BO·Sl,AAU
-TPIHl 198I,AAI BACKHOE TEST PJT
GEOPHYSICAL SURVEYS:
~ S't'N SEISMIC REFRACTION SURVE't END
OR TURNING POl tiT
-DW·C .1975.0AlllES SI!IOOI~E
REFEAENCE•··.ASE MAP FROM CO~I978-l•,.aoo'
WATAN~TOPOGRA'PHY,SHEET 8813
OF 26,Ci:lQRDINATES IN FEET, ALASKA
STAlE ~AHE! tZONE 4)
SW-1 I918,SHANNON 8 WILSON
SL lJO-r 1980-81, WOOOWARO-C\.. YOE CONSULTANTS
PROPOSED BOREHOLES;
QHD·AA HAMMER DRILL BORING
PROPOSED GEOPHYSICAL SURVEY~
~SEISMIC REFI1ACTION l..INE~f'Hi\SE l:
~·SEISMIC REFRACTIOf.! LINE•PMSE :lt
(DASHED UNES .6.RE OPTIONAL)
NOTE
l SEISMIC REFRACTION UNES SLSl·A 11\..~JGH SlB2-Q
ARE SHOWN ON FIGURE 4.2.
. o"-. . / ~~·~····.
SCALE 0 200 400 FEET e:~~·~Siiiiiiiiiiiiililiii'
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"" 1111
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REFE.~ENCE: QASE MAP FROM COE.1978-I"•20<tWATANATOPOGRAPHY, SiiEET 8 !U3 OF 26.
COORDtNATES IN F£ET .. Al.ASKA STATE ~LANE (ZONE4}·
~
II)
~
WATANA
MAP
LEGEND
LITHOLOGY:
.DIORITE TO QI)ARI.:. :Oivrtm.toct.t.'OES
MINOR GRANODI~RlTE
ANO.ESITE PORPHYm; tNct.UOES
MINOR DACITE .A.t.ID LATITE .
I~:; rj PtORITE PORPHYRY
CONTACTS:
J~ .LlT ... OLOGIC, DASHED W&Rt; 1Nf£R~S:'I~
CIP WHERE KNOWN
STRUCTURE:
~;::7il
~@
'-x
E""·::s:.=t
~:;;.~
7~7 ,. .......
70~&o+
EJ.
OTHER:
SHEAR, WIDTH GRS.'reR~ 10~-::,
VERTICAL UNLESS ill? SH~~
SHEAR,. WIDTH t,i;SS TP..AN iC FEeT.
INCLINED, VERTICAL, EX'lE.NT WHERS:
KttO'NN
FRACTURE tON~. W>tlnl ~~~5AttR ~
10 FEET, VERTlC:AL U!U .. F.SS "OlP SHQ~
FRACTURE ZONE. WlOnl U:SS Tl:iAA
10 fEET, INctlNED. VER'H~iU., EXTE~"V
WHERE KNOWN . .
JOINTS: INCL!WEO, Cit>~ tN"Cl.lNEO.
VERTICAL {SETS lAm> U ONU'.
EXCEPT FOR OP.EN .$t1ltiTS l
AIJERATION ZONE. WID1"H ~ SHOWtlt
A WJ-l JOINT STATION
~ GEOLOGIC FEA~
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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 wide,
stretching over 12,000 feet from a point on Deadman Creek to the approximate
thalweg of the ralict channel, including approximately 7t000 feet of exposure as
bluffs overlooking the Susitna River, a total area of about 1,075 areas (Figure
3.1). The area has been identified ·as the most favorable source for impervious
core material with a total estimated site requirement of approx-Imately 8.25 mcy ..
The information, to date, on the borr0\"1 site is compl"ised of seismic refraction .
surveys, auger holes, sc~eral deep rotary drill holes 9 and shallow test pits •
3.2 -Objectives
The objectives of the FY8~ program are to obtain sufficient details to confirm
the stratigraphy developed during feasibility, and develop a clear understanding
of material properties, g~ound water, and permafrost conditions.. Results of the
FY83 will form the basis for the subsequent detailed design level investiga-
tions. The long-range objective of the Eorrow Site 0 investigations will be to
determine:
(a) Borrow site stratigraphy and extent of each of the various identified units
of interest to a level, adequate to confirmed v~lume-distance relation-
ships, stripping parameters, and producable volumes.
(b) Define site and adjoining areas, ground water, and permafrost cond~tions 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) Continuance of material properties and their influence on proauction, pro-
cessing, and placement requirements.
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(e) Engineering properties of the material, as required for placement in the
fi 11, including p1 acement water content, gt .. adat ion, plasticity, and compac-
tion characteristics. Explorations will place emphasis on detailing
volumes of reserve with various properties.
2.3 -Approach
Since Borrow SiteD lies within the relict channel areas, an exploration for
borrow materials will also provide desired information on the relict channel
stratigraphy.
The Phase I summer explorations on Borrow Si-ce D will be limited to surficial
outcrop mapping during early summer to delineate exposed borrow materials and
bedro·ck. In addition, a limited seismic refraction survey will be performed in
both the borrow area and-relict channe 1, as we 11 as a a.uger/rotary dri 11 i ng pr·o-
gram which is intended to provide high quality split spoon and 11 Undisturbed 11
core samples ·to a depth of approximately 150 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 with casing, hollow stem
auger, and conventional wireline coring methods of advance. It is planned that
each boring will conmence with large diameter casing capable of obtaining 3-inch
samples to an approximate depth of 75 feet. It is anticipated that from 75 to
150 feet the auger system will not be effective, thereby a w1r-eline drill rod
will be used with a "casing advancer" rotary ticone bit. Depending on drilling
difficulty and sample recovery, it is likely that this method will, in a large
portion, " , 1 ace the auger i ng method of advance. Norma 1 advance procedure wi 11
involve use uf frequent samples, as described in a fo11owing paragraph, with
rotary drilling to overcome boulders and cobble zones and to advance between
samples. Proposed borehole and seismic line locations are shown in Figure 3.2.
The information collected during the summer program will be used to locate t.he
drill sites for the larger diameter hanxner drill boring to be conducted in the
winter when 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
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inside diameter (6 inches) drill p·ipe (Figure 3.2 and Table 3.2).. Continuous
' .
sampling of the bJown out cuttings will provide large samp'les of the various
stratigraphic units for use in geologic interpretation of the stratigraphy and
in materials laboratory testing.
The drilling program in Borrow SiteD will be directed to:
-Obtaining information in locations where the stratigraphy can best be deli-
neated and sampled, and;
-Obtaining· bulk ·samples of ·the potential borro~t~ materials in locations where
representative samples have not yet been obtained.
Due to the primary need for stratigraphic information and the fact that syste-
matic pattern explorations of the borrow reserves will be ccojucted in the su!'-
sequent stage of design investigations, the emphasis of tne FY83 Phase II pro-
gram will be put on stratigraphic data collection.. The sampling and instru-
mentation activities carried out in this progra'TJ will be directed at maximizing
the level of information obtained from each boring,. Long-term instrumentation
will be installed to provide baseline thermal and geohydrologic data. The vari-
ous methods that will be utilized are described individually below:
(a) Full depth sampling to provide material for geologic examination of the
lar·ger particle sizes and for laboratory testing.
(b) Drive and core type sampling as is appropriate to inc·lude 2-and 3-inch
standard split spoon with standard penetration blow counts. Denison samp-
ling, and dry-blocked and conventional fluid circulation core barrel samp-
ling.
(c) Casing drive tests (open casing drive tests) for general correlation of
stratigraphy and density.
• (d). 11 UndisturbedU samples, using such samples as fixed piston UQsterberg 11 ,G
Shelby, and 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. "dry11 zones. Due to the
preliminary indications that the area has 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 wi 11 be
correlated with the relict channel installations.
(f) Limited aquifer permeability testing such as falling head and/or ccnstant
head tests will be performed where possible to obtain orcter-of .... magnitude
information on the ranges of permeabilities of the materials in the borrow
site.
(g) Permafrost detection will be limited to observ-ation of both seasonal and
permanent frost during drilling, and installation of thermistors in many of
the holes. The probes will then enable detection of_permafrost in the
following year after the frost has stabilized and of the depth of annual
frost penetratjon during the winter. This information.wil1 then be uti-
lized to evaluate the frost conditions likely to be encountered in excava-
tion and at a later stage of design will be used with the results of a11
thermal investigations data to develop the borrow site production method to
minimize the adverse effects of the frost in excavation and fill
p 1 ac·ement •
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I TABLE 3.1: FY83 EXPLORATORY PROGRAM -PHASE I
WATANA RELICT CHANNEL/BORROW SITE 0
AUGER DRILLING PROGRAM
I Boring* Approximate
Depth (ft) Number Location*** Instrt.rnentation Purpose --
•• AH-A 0/RC on SW-3 Assune all drill SP Expand stratigraphic
holes to 150 feet correlations across D/RC.
AH-B 0/RC <ln OM-A Same as above p::: 3 Same as above •.
T
I AH-C 0/RC at Inter-Same as above p = 3 Same as above.
section of OM-A T
and DM-8
I AH-0 0/RC, 100 feet Same as above p = 3 Same as above.
E of SW-5 T
A H-E 0/RC at inter-Same as above SP Same as above., :I section of SW-3
and SLS0-7
~
AH-F RC on SL81-14 Same as above p = 2 Same as above.
I AH-G RC on SLB0-2 ~)ame as above p = 3 Same as above. -..
AH-H** !lC on SLB0-1 Same as above SF Sarr.e as above.
I. AH-I** RC on SL82-A Same as above SP Same as above.
AH-J RC on SLB0-1 Same as above p = 3 Same as abov.e.
I AH-K** RC on SL82-B. Same as·above SP Same as above.
AH-L RC dn SW-3 Same aS" above SP Same as above.
·I AH-M 0/RC on SLB0-7 Same as above p = 3 Same as above.
T
AH-N**' 0/RC near TP-21 Sameas above SP Same as above.
I AH-0** RC Same as above SP Add detail to stratigraphy
and material properties.
AH-P** 0 Same.,as above SP Same as above.
I AH-Q D Same as above p = .3 Same as above.
T
AH-R D. Near, DR-14 Same as above SP SaJT.e as above •
I on SW-3
AH-S** 0 .on SLB0-8 Same as above SP Same as above.
I AH-T** RC at intersec-Same as above SP Same as abcwe.
tion of SL81-14
and SL82-C
I AH-U RC on Sl81-15X Same as above p = 3 Same as above.
AH-V ·Rc on SL82-A Same .as above SP Same as above.
AH-W RC on SLB0-2 Same as above SP Same as above.
I AH-X RC between DR-19 Same as above T, SP Same as above.
and DR-20
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TABLE 3.1 (Cont'd)
Botmg*
Nuroer
AH-Y**
A H-Z
AH-AA
AH-88
AH-CC
AH-DD**
AH-EZ:::
AH-FF
AH-GG
AH-HH
AH-II
AH-JJ
AH-KK
AH-Ll
AH-MM
AH-NN**
AH-00
AH-PPH-
Approximate
Location**..:'
D/RC on SLS1-6
D on SW-3
RC between DR-26
and DR-22
RC on SLSt-13
RC on SLB0-1
RC on SL82-8
RC on OM-A
0/RC. near AH-D-8
D on OM-A
0 near AN-0-10
and AN-D-11
0 near AP-18
0 between AP-10
and AP-11
D near TP-14 ·
D near TP-10
RC onSL81-14
0/RC on OM-A
D on DM-A
RC near OR .. 20
RC near SL81-15
0 near SL81-19
D, SW of RR
D, nearTP-13
Depth (ft)
Assume all d~ill
holes to 150 feet
Swne as above
Same as above·
Same as above
Same as abovee
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 aa above.
Same as above.
Same as above.
Same as above.
Same as above.
Same as above•
Miscellaneous, locations to be determined
Instrumentation
SP
SP
P = 2, SP
P = 2, SP
SP
SP
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 af;l above.
Same as above.
Same aa above. .
Same as above.
Same as above.
Same as above.
Same .?;S above.
Same as above ..
Same as above.
Same as above.
Same as above.
Same as above.
Same as above.
Serile as above.
Same as above.
s~~~ as above.
SSllYJ as above.
Same as above.
Same as above.
AH-QQ
AH-RR
AH-SS
AH-TT
Atf..;.UU
AH-VV
AH-WW
AH-XX
in field, also for more detailed investigation
of freeboard dike.
*Borings listed by priority.
**Auger borings adjacent to hammer drill holes.
***See figures ?•2 and 4.2.
"" 0 = Borrow Site 0
P : Piezometer tips (pneumatic)
RC = Watana Relict Ch~nne1
SP = Standpipe Piezometer
T = Thermistors
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TABLE 3.2: FYBJ EXPLORATORY PROGRAM -PHASE II
WATANA RELICT CHANNEL/BORRO\f SITE D
HAMMER .DRILLING PROGRAM
Boring*
Number
HD-A
HO-B
HO-C
HO-D
HO-E
HD-F
HO-G
HD-H
HO-I
HD-J
HD-L
HO-M
HD-N
Approximate
location'"*
RC on SLB0-1
near AH-H
RC on SLB2-A
near AH-I
RC on SLBZ-B
near AH-K
RC on SLBZ-B
near AH-00
RC near DR-2u;
and AH-PP
RC on SLB0-2
RC on SW-3
D/RC on SLB1-6
near AH-Y
RC near AH-0
RC on Sl81-14 and
SL82-C, near AH-T
0/RC on OM-A.
near AH-NN :
D/RC near TP-21
and AH-N
D on Sl80-8p near
AH-5
D on SW-4
TOTAL
*BOrl.ngs·l~sted by priority ..
Approximate
Depth .(ft)
zoo
450
300
225
50
150
425
425
525
225
400
600
250
4,.325
**Auger borings adjacent to hammer drill holes.
***See Figures 3.2 and 4a2.
D : Borrow Site 0
P = Piezometer tips (pneumatic)
RC = Relict Channel
SP : Standpipe Piezometer
T = Thermistors
... I
Instrumentation***
p = 3
T
p = 2
T
p = 5
p: 3
p = 3
T
p = 3
p = 2
p = 5
p: 5
T
p :: 5
T
p = 3
p = 5
T
p = 3
T
p = 3
Purpose
. Stratigraphy material,
properties, ground water,
and permeability. ·
Same as abeive. On main
thalweg.
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.
P = 50 tips, allow 20 additional tips for
miscellaneous locat;ons.
T = 7 strings, allow 3 additit..'!lal strings f'or
miscellaneous locatio'1S ..
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FOG LAKES
RELICT CHANNEL
\
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\ rBORROW ~fiTEF
I ·~
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~·I ~ \
WATANA
BORROW s"tTE MAP
LOCATION MAP
LEGEND
c:-=.:1 BORROW/ . · QUARRY liMITS
SCALE O~~t;;;;;::d -2 MIL!:S
' ' ' ----\.· .. -~·
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.. «-·-
}'_., -~ ~ e
N3,230,000
N 3,2.32,000
N 3,256,000
REFERENCE~ BASE MAP FROM 1978.COE-1••2.00' tlAMS!T£ TOPOGRAPif'l',
SHEETS 13-15,18-ZO OF 2.6
&' . _/
o'-... ~
.'i i b. ,...; \ a
j_. ~\. ~ ~.·. + ·~
CONTOUSS 0~
FOO Cu.Rtn'
.... • :1: en
BORROW SITE D
now ;cas =-
0
AH-TT
PROPOSED FY 83 EXPLORATION PLAN
LEGEND
CONTACTS•
----BORROW SITE UM!T
GEOPHYSICAL SURVEYS•
• IF\.. \__J)
(
,,
,&S\\'-3 SEISMIC REFRACTION SURVEY END OR Tl!R~ING POINT
OM-A 1975, DAMES 8. MOORE
SW-3 1978, SHANNO~ a WILSON
SLB0-11 1980-81, VIOOOWARD-CLYDE CONSIP.;..~~'TS
BOREHOLES AND TEST PITS;
0 t::ft'-Z1 1978, COE ROTARY DRILL BORIIIIG
0 AP-2.1 197S, COE AUGER BORING
~AH-lrl2.!9BO,AA1 AUGER BORING
W TP-U 197e, t::OE BACKHOE lEST PIT
® BUlk SAMPLE LOCATION
PROPOSED BOREHOLES•
__Jf-· QAH-A AUGER BORING
Y . QHD-L HAMt..'EF( DRILL BORING
NOTE -:~ l, HAMMER DRILL f.IORINGS ARE lOCATED .~TO
AUGER BORINGS.
1 ~~
. . ' ) ,/ . C::_.l ( SCALE b too
. N
.EJO FEET
I
FIGURE 3.2. fAil
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4 -RELICT CHANNEL
4.1 -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 leakage. The preliminary explorations and geologic
mapping indicate that both of these areas may be abandoned Susitna River chan-
nels or 21 relict channels11
, one betwe~~ Deadman and Tsusena Creeks, and the
second in the Fog Lakes area(l).
The concern regarding these areas are:
~
(a) Potential for excessive reservoir leakage of such magnitude as to affect
project economics.
(b) Potential for excessive local gradients under reservoir head which might
cause piping of material and, hence, induce progressive failure of the rim
material with ult.imate breaching of the reservoir.
(c) Overburden instability or seismic liquefaction potential which could result
i rr breaching of the reser·voi r confinement.
(d) Crest settlement due to saturation and permafrost thawing.
4e2 -Objectives
The objecti\ ~';e FY83 program wi 11 be to adequately assess the potential for
these occurr: The following factors must be adequately defined to allow
prope.r evaluat, .-J of the physical behavior of the relict channe·ls under project
operating conditions •
-Stratigraphy;
-Materia 1 properties;
-Boundary conditions;
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-Geohydrology;
-Permafrost conditions; and
-In-~itu physical condition of materials.
4.3 -~pproach/Discussio.!!_
A two-phase program of exploration is proposed. rhe FY83 prograrn wj 11 primari.ly
address the more critical Deadman-Tsusena area relict channel which has. been
designated as 11 the Watana Relict Channelu(l}. Preliminary assessment at
the Fog Lakes Channel show the freeboard at Fog Lakes is significantly higher
than the Watana. Relict Channel, and the local and overall gradient is much flat-
ter and the flow path muct(ionger than the Watana Relict Channel which minimizes
any apparent hazard. ·rt is therefore proposed to do only limited seismac re-
fraction ·investigations in the Fog Lakes areas during FY83 with a more intense
investigatio~ being performed in the area during FY84 (Figure 4.1 and Table
4.1). That investigations will be conducted to assure that significant f1ow
paths or liquefiable zones are not widespread in the Fog Lakes Relict Channel.
The Watana Relict Channel has a flow path of approximately 1-2 miles with an
average gradient of about ten percent and a stratigraphy which (based on the in-
format ion to date) does show potential for seepage.. In add it ion, very limited
subsurface data suggest that potentially liquefiable material may be present
with the channel{l).
The FY83 explorations will be jointly conducted with the Borrow Site 0· program
since the borrow site 1 ies within the confines of the relict channe.l areas (Sec-
tion 3). The principal objective of the ·FY~3 program is to obtain representa-
tive samples for strati'graphic identification, material properties distrib1'Jtion,
and geohydrologic conditions in t'1e relict chan~el ..
The FY83 program for the relict channel will be performed in two parts, a summer
-Phase I and winter -Phase II program. Thi.s is principally due to field
logistics and the inability of transporting large .. irilling equipment overlund
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until the winter. Therefore., the summer program will use smaller helicopter
transported drill rigs tha~ will evaluate the upper 100~150 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
_ _program.. The objectives of FYB3 are to:
0
Phase I
The objec~ives of Phase I are to:
-Perform surfacial mapping of the relict channel;
-Define the surface_ and subsurface hydrologic regime in the upper 100-150 feet;
·-Obtain undisturbed and disturbed samples at depth to identify
stratigraphy and material properties;
-Install instrumentation for monitoring ground water and permafr9st; and;
-De 1 ineate extent of Fog Lakes Relict Channe 1.
Phase· II
i
The objectives of Phase II are to:
-Confirm the geometry of the re 1 ict ·:hanne 1;
-Obtain large bu1k and undisturbed sample at depth for stratrgraphic delinea-
tion and material properties;
-Evaluate the geohydrologic regime where possible; and
-Install instrumentation for monitoring ground water and permafrost._
Phase I will involve drilling approximately 50 borings disti"ibuted throughout
the Watana Re.lict Channel and l'imited geophysical program (Table 4.2). Several
of these bor'ings wi11 also serve for investigating Borrow Site D. Propos,ed bor-
ing locations are shown in Figures 4 .. 2 and 4.3.
The drill equipment will have capability of drilling a 6-inch sampler in the
upp_er 20-30 feet; reducing to 4-inch samples to 75 feet, and subsequently reduc-
ing to standard 2-inch samples to to fu11 deptll of 150 feet. The intent is to
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obtain .a large diameter sample as possible to maximum depth with the intent of
determining the following conditions
-Soil moisture content;
-Geohydro1ogic condition;
-Soil density;
-Soi 1 gradation;
-Stratigraphy and sedimentary origin;
-Permafrost conditions; and
-Obtaining samples for laboratory testing to determine plasticity limits, com-
paction, permeability and dispersion.
The results of the summer investigations are expected tc provide a model or
stratigraphy, ground water and permafrost regime, and material propert]es in the
upper 100-150 feet of the relict channel for use in subsequent design ana esti-
mates9 and to assist in laying out the deep drilling program to be performed in
the winter program.
Phase II wi 11 uti 1 i ze the same 1 arge diameter nammer t'ri 11 that was described in
the Borrow Site D (Section 3). Approximately 15 holes are planned to penetrate
to bedrock in the relict channel. The drill cuttings will b.e used in strati-
graphic del ioeation and bf)rrow materials, testing. In addition, the drive and
drilled sampl·ing methods utilized in the Phase II will be used to obtain
11 Undisturbed 11 samples for precise laboratory tests. Proposed boring location
for the hammer drill are shown in Figures 4.3 through 4.5.
As in Rorrow Site D, empnasis in tn:;. sampling program will be placed on obtain-
ing maximun size samples for stratigraphic information and materials lnVestiga-
tions. The various sampling methods that will be available are lfsted below.
(a) Full depth sampling and logging of drill cutting which will provide limited
supplementa[ material and stratigraphic information.
(b) .. Urive and caring sampling, using 2-and 3-inch standard split spoon
s~mples, as well as, special s~mplers, such as the Denison.
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(c) 11 Und1 sturbed 11 samp 1 i ng, using spec1 a 1 11 fl oati ng tubeu or pi star type
samples such as the nGusn and "Osterberg" and various diameters of Shelby
and similar split or soli.d thin wa11 sampling.
(d) Casing drive testing, us.ing the hammer drill (winter) to ascertain relative
vari aticos in density.
{e} Water level detection and monitoring, both during and after to drilling
operations.
(f) Installation of well casing scr«;ens and piezometers for subsequent observa-
tions and aquifer testing.
. .
(g) Permafrost monitoring through cutting temperature measurement~ obser·vation
of ice in the samples taken, and installation of frost probe PVC pipe for
continued observation. If significant frost is detected at depth, a full
thermistor string may be installed if thought to be appropriate ..
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"
Seismic:
Refraction
Line No.*
Sl82-FL-A
. SL82-FL-B
SL82-FL-C
SL82-FL-D
SL82-FL-E
SL82-FL-F
SL6~-FL-G
TABLE 4.1: FYSJ EXPLORATORY PROGRAM
FOG LAKES RELICT CHANNEL
GEOPHYSICAL SURVEY
Location**
Approximate
Leng!h (ft) Pureose
Channel A 22,000 Determine gradient of
channel.
Channel B 15,400 Determine bedrock gradient
of channel.
Olannel A and 8 22,000 Width of Channel A and B.
Olannel A 22,000 Determine bedrock gradient
of possible additional
channels.
Channel A 15,4_00 Upstr.eam width of channel.
Channel B 9,900 Width of channel.
Channel B 5,500 Width of channel.
*Th~ seismic lines shown here are based on limited geologic: data suggested for
more complete definition of the c:hannelso The niJmber and orientations of
seismic: lines will be based on additional geologic: mapping.
**See Figure 4.1
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Seismic
Refraction
Line No.*
SL82-A
SL82~B
SL82-C
SL82-S
Or
SLB2-T
SL82-U
SL82-V
SL82-W
TABLE 4 .. 2: FY83 EXPLORATORY PROGRAM -PHASE I
WATANA RELICT CHANNEL GEOPHYSICAL SURVEY
Locat icr<t**
Approximate
Length (ft) Purpose
Relict channel 6,600 Bedrock depth, overburden
conditions.
Relict channel 6,600 Bedrock depth,
conditions.
overburden
Relict channel 1,100 Tie in lines SL81-14
and SLB0-2 to complete
coverage.
Reli~t channel 6,600 Detail of main relict
channel thalweg.
Relict channel . 6,600 Same as above.
Relict channel 1,500 Tie in lines SL81-16 and
S~81-15X to complete
coverareo
Borrow Site D and 1,100 Tie in lines SL81-16 and
relict channel SL81-18 to complete
coverage.
Relict channel 3,500 From SL81-13 tn Tsusena
Creek to complete coverage.
*Seismic lines listed in order of priority, SL82-D through SL82-R on Table _.
**See Figure 4.2 ..
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FOG LAKES RELICT CHANNEL
PROPOSED FY 83 'EXPLORATfON PLA~t·
LEG EN[}
GEOPHYSlCAL. SURVEYS;
~· SEISMIC REFF>ACTION. SURVEY LIN£
F'..:ITO
FL.-48
PROPOSEr' GEOPHY51CAL SURVEYS~
~SEISMIC REFRACTION SU~-·~lDAsW''D ·~ SLS~-ARE ALTERNATIVE ALIGNMENT$ . QE~ENDIN~~ON.
FL-A FlaD GEOLOGY INTERPRETATJON:
SCALE
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\F
· DETAILED SORROW SITE 0 EXP.LORATION
MAP SHOWN ON FIGURE :3.2
' ' ~-,_;
tONtiNU~ OF'F
PAiiE
"-· .• o. ··-"-~~ _,,, __ ... ~-_,,-••
DETAILED · DA"'.stTE SEISMIC l.INE .
ANO BORING EXPLORATION MAP
StlOWN :()N FIGI.!RE 2.J-. ·
WATANA REUCT CHANNEL
PROPOSED FY .·~ EXPL-6RtffteN·'-Pl..AN
!·.
' '
!
!
.·, .....
LOCATION MAP 0 " SCALE 1:7 ': ~:: Z
LEGE. NO
BOREHOLE.S AND TEST PiT$:
. ..-----~' OO·Je l97S.tOE: ROTARY DR I Lt.. B.ORINC
GEOPHYSICAL. SUR/I.E"''S':
& SEISMIC REFf>.J,CTION SURVQ' f:Nn (lfi TU~ ~
t9'75,.0AMES a MOORE /
1000 2000 FEET .
SCALE
FIGURE 4 .. 2. . ·
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1:
z
0
i=
2400
~. 1600
5 w
1200
z
0
i=
2400
~ f600 Ul
-l u:
12,00
l ' .
11(
150..._. AZIMUTH --zas•
OF SECTION
1
HD-I HD•v ·AZIMUTH PROJECTED PROJECTED !06°~ ••. ·. ·· · ·. .. -··--3t5• HD~-H 6()0'.NE DM-A 20o,·sw liO-C Of SEn~~~ij .
. . 1· ?ROJECTEb' PI*' t.'TED
SL6H6 . . 1. 400
1· 'NE . · ~o~~E' r:. . ~O~ECTED
NOP.MAL 'MAXJMUJ.t O.."£AATHG
LEVEL !;:L2185
HOF-MAL MAXIMUM i , SW-3 • · st..S0-2. SL"'" .., 1 •. SLSC·I 500'NE O?£RATI~G POOL EDGE ~ 1 : &"' . f I· i J . DR-Zl l i [
SUSITNA RIVER l {LOOKING DO'NNSTREAM)
EL 1500± ....
. .~ -----· _________ ...,
~----l . I j[ I I . ·' i SL 82-A rlfTSUSENA CREEK • .,~ •. -......, • · . ELlGBO
_____ ~ .. c------------~~-, --------~.~--------~-L , I.. ... . . .. t . . .. · ·
_...,.,.,..-.....----.-'"1.,~, €" -~-~-------. ...,;,..;--~ -i --L
---~~~,--------~-~-~·,..!..-· ------------.,;,..~...... f--~· '-'..;iJ't·v'Ut-~'"!~-: ~~ ~ .,.....-~ ,;.~
THIS AREA ~iELY
9ooo• UPSTREJIM OF WATANA
DAM CENTERUN£
..
·1 SUSlTNA RIVER TO TSUSENA CREEK
ESTlfMTED THAt..WEG ( DEEPEST PATH l
SECTION w.:..rt.t
~315°
HO-G
. PROJECTEtl
400'NE I ~ECTEI)· ~~01ECTED
SW-3 St. 80-2 200'SW .2001" NE H0-8
t t ~~
NORMAL.MAX!I>WM OPERATING ' r~~E:~E,:~ I SL82-B st.. so··· .. , IOO'··INE L~VEl EL21~ OR-19 ... u O~IS ' ~ ,.. ,..,..,..,=~~g;~==~·--I l Sl82-A
,: ---------.,.~ I. j_. =t .
SUSITNA RIVER
(LOOKING DOWfm'REAM)
EL1470%
7 ,
---._.;.,.,---~--'
-----~·~--------. ·. . .
c ·-,__ -------~-"j!~~·~ -·~ -----:-:::...-:.,...,...!----------
2400
2.000
1600
1:!.00
LEGEt~O:
GONTAC1S:
----APPROXIMATE 7i:>f" OF ROCK
GFOPHYSICAL SURVEYS:
A. "'W•' INTERSECTION WITH SE:ISMIC RE~ .I., ' LINE:
t>M·C 1975, ~J.tES a cMOORE
SW•I 1978, S\iANNO;Il· .& WILSON
St. BO-t 1980, WOOOWAIID-CCttlE c~
st. 81•2 1981. WOOOWARO·c®E CoNst.Jll~<'lS
BOREHOLES~
DR-I~ tOE ROTARY D~ILt.. BORING
PROPOSED BC;~'HOLES:
HO-A HAMM.ER DRILL BORING
PROPOSED GEOPHY$lCAL S\JRVE't::.
tSL 82-A SEISMIC REFRACTION liNE
NOTES
I THIS. .AREA APPRO)(JM,ATELY
3000'UPSTREAM OF WATAHA
DAM CENTERL!NE "THE FINS" TO TSUSENA CREt:K
SHORTEST FLOW PATti
SECTION W-16
I. PROFILE AND SEISMIC UNE LOCAllClNS s:;-:JOWN ON
FIGURE 4.4.
2. SECTION ALOfiG DM,..A SHOWN ON FIQ..E ·•US. •
WATANA RELtCT CHANNEL PROFILES
. i;
. 1
3. VERilCAL A.~ HORIZONTAl:. SCALE ~.
.at SURFACE fROflLE fROM .1"• ZOo'~
COE 1978 TOPOGRAPHY~ W ::£25 fE~T.
S. TOP OF ROCI< NORTHWEST OF SLSO-t iS PROJECTE!>
UP TO 300 .FEET TO PORTM't ~ 'n!A.U!IEG t'RQftt,
6:. AQGE:R BORINGS IN REl.iCl' CHANt~&. ARE SHOWN OK
fiGlJRi! 4.2.
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~ ~~ ~ wj r-
w
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?f3224,000
I
~· ~.
!''
1 \.
l ru ~ ... ,
f!t t{
wt WI
l
·.::.:;;:~.-:._
WATANA. RELICt CHANNEL.
PROPOSED t=Y83 HAMMER DR1LL BORINGS
0 ~ . #
........ ~
J. ~~ ~ ";{'
lOCATION MAP
LEGEND
~-TOP OF BEDROCK, CONTOUR INTERVAt. ~0 FEET.
---~-50 fOOT .CONTOURS ~1-iEP.
0
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I 2.400.
I 2.300
I 2200
-!-w
I
~ 2100.
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19.00
I 1800
I 1700 L
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/ / \., {
\
_045 • ...._....., AZIMUTH ~-::>25 .,
OFSECTION '
AH-NN/11,-K All-Ot~o-r
PROJECTED
700'NW
l
AH-PP/.HD-E
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WATANA RELICT CHANNEL-EXPANDED THALWEG SECTlON
LEGEND
LITHOLOGY:
~::;:;~tr.} c
~E,F
~~~~~m G
·~H
CONTACTS~
--. -KNOtt'N UNlT CO~TAcT
---I~FERRED UNIT BOUNUARY
~~ BEDROCK SURFACE WHERE. DRILLED •
"'·'~'""'"' NORMAL.IdAXlMUM OP~RATING LEVEL EL21SS
BOREHOLES=
DR-2& t:OE. ROTARY CORE BORINGS I]:-NOTED AS FROZEN DURING DRILWNG
PROPOSED BOREHOLES:
HD·E liAir\MER DRILL BORING
AH-'B Al.'IGER BORING
NOTE
l Lo:A~ OF~. M..Cim !IEm.tte ·~ \'lil--t!, Otr
fteVRE 4.4. •
0' ao tso ·F'Ef.T v~
!;C~ ~ = ;;;; '
SCALE 0~~~4005iiiiiiiii~800 F£Er HORIZONTAL
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5 .. BORROW SITES E and I
5.1 -General
Bo(row Sites E and I include the Tsusena Creek outwash plain and Susitna River
flood plain from a point approximately 2-1/2 miles downstream of 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 requirements totaling
approximately 40 mill ion cubic yards( I). The information in these areas,
to date, has been compiled from seismic refraction surveys, air photo interpre-
tation, and various test pits and shallow auger holes. (!
5.2 -Objectiyes
Th.,• overall objective of the Borrow Site E and I investigation is to obtain four
types of information ot,)eded for refinement of construction processing CLVld pro-
duction costs, confirmation of haul distances to obtain adequate reserves and
development ·of engineering design parameters for d~ des1gn. These are:
(a) Borr·oy; site configuration, including definition of confirmed volume-
distance relationships,, latera] and vertical extent of suitable materials,
and basic. g·roundwater level and stripping depth paramuters necessary to
allow optimization of production methodology, se1ection of least-cost
mining methods!.! and determination of in-p1 ace reserve figures.
(b) Limits of reasonable excavation depth determination bas~d on geologic con-
,
straints, stratification of deposit, and inherent stability of the mate-
rials., These iimjtations will have significant impact on the actual eco-
nomically recoverable reserves which, in turn, can be expected to influence
maximum excavation depth, net exca,vation ·rosses~ and, consequently, equip-
ment selection and ovt:rall land requirements for adequate development.
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(c) Material gradations, including both typical and local variations in the
material quality, which will influence production methoas and requirements
and possible processing.
(d) Engineering properties of the material for use in concrete, filters, and
dam shells for use in selection 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 andi therefore borr-ow,-s.ite
quantity ana reserve calculations; and
{b) Determine material properties.
5.3 .,, f\pproach/Disc~ssion
The amount of worK that can be done within the FY83 is limited by time and the
samp1inQ. equipment which will be mobilized to the site .. The large hamner drill,
which is p 1 an ned for use in the Re 1 i ct Channel and river areas (Sect ions 2
through 4)., will be utilized to drill several confirmatory borings to maximum
practical excav·ation depth below river level in the primary source ~rea of
Borrow Site E with t~·£e intent of verifying the seismic data and obtaining sample
gradations and suitable test samples {Figure 5.1 and Table 5.1) .. Use of this
piece of equipment shi>u1d verify the general overall suitability of the source~
ascertain the approximate upper size 1 imits and range of the gradation, provide
adequate samples for physical and dura.bil·ity suitability, and give an int.licatian
of variability of the deposit with depth.
Subsequent studies for final aesign investigations will determine the actual
mineable limits, exte.'lt of variation in mat~ria1s~ ground water elevation, and
the precessing that will be requir~d for each of the major gradation var~·at ions.
The. FY83 summer program in Borro~1 Sites E and·I will be limited to completion of
surficial geologic mapping during Phase I to delineate all exposures af rock and
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borrow materials with the intent of defining material limits and geomorpho1~gic
features which may give indications of expected material gradations. It is
anticipated that the information obtained from the mapping will be limited to
identification of relict terraces, alluvial fan deposits, and river flood plain
limits within the borrow site. Phase II borehole locations will also be
established durhlg the sumner program.
The winter program wi 11 invo 1 ve use of the large hammer dri 11 with 1 arge inside
diameter pipe to continuously sample the si.te from surface to maximum practicai
excavation depth which is estimated at 125 feet below water level. The dri 11 ing
will be distributed over the length of Borrow Site E to provide a general over-
all view of the borrow materialso Due to the wide spacing cf these borings,
stratigraphic correlation 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 re1ative1y level dri11 setup to minimize setup time and,
thereby'j maximize the number of holes drilled.
(b) Placement of at least ten of the ho~fes on. previous seismic 1 ines to verify
the S·::i smic data interpret at ion.
(c) Placement of several holes along the active river margin to verify the
off-end-of-line seismic interpretation of alluvial depth and compo~ition.
{d). Placement of a line of holes near the north limit of the flood plain to
confirm the average depth of alluvium and to assure that bedrock l:~vel does
not rise rapid1y in the north and·east portions of the borrow site.
(e) Spacing of the borings so as to optimize the interpretative value of the
sampling, both for determination of the distribut:;on of gradations and for
the stratigraphic conditio1s that may vary from area to area in the bm 1ioow
site.
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Borehole san1J)ling will be conducted as listed below:
(a) Prima·ry sampling will be full depth cuttings sampling up to 4 inch size
particles.
{b) Split spoon or Denison/Core Barrel samp1ing, as necessary, to sample fine
sar,~, silt, or clay layers which may be encountered.
{c) Casing dive tests (op(,, casing drive tests) for general correlation of
stratigraphy vers·~~ tt(.nsity for use in estimating '~xcavation requirements.
Since the borrow site is planned for dragl ine excavat·ion, detailed density
testing is not considered appropriate.
(d) Water table detection and monit(iring to provide information on potential
dry versus ~et excavation. Because the water table is expected to range
from 10-30.feet in depth, simple standpipe piezometric monitoring will be
utilized to allow continued monitoring of seasonal variations of the water
table with rainfall and river level.
(e) Frost detection will be limited to direct observation of drilling rate and
teiTiperature measurements of cuttings. No permafrost is expected in the
borraw site, but the depth of seasonal frost wi1l be measured and checks
will be made throughout drilling operations to recora. any indications 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 install€'ed
to approximately 30 feet to provide the necessary anchorage length and
reading coverage for detection of annual frost penetration thermal probe
headings.
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TABLE .5.1: rY83 EXPLORATORY PROGRAM -?t:.~SE II
__, ___ ...;B;;.;;O~RR;.;,;;O~W...;S;;.;;I;..;;.;TE;;;...;;;;E...;H.;.;..;A~MM..;.;;E;.;..;..R. DRILLING PROGRAM
Boring* Approximate
Nuniler Location**
HO-A SW-10, south end
HO-B SW.-10, north end
HO-C SW-12, north end
HO-D SW-12, eer!ter
HO-E SW-12, south end
HO-F SLB0-9, north end
HO-G SLB0-9, center
HD-H SLB0-9, south ena
HO-I SLS1-17
HD-J SW-13, center
HD-K SW-13, south end
HD-L SW-13, north end
HO-M On river bank
HD-N On river bank
upstream of Tsusena
Creek
HD-0 At intersection of
SL80-11A & SLB0-118
HO-P Upstream on Tsusena
creek
10lTAL
~rJ.ngs !J.eted by priority.
**See Figure 5.1.
***SP = Standpipe piezometer.
FP ~ Frost pro~e.
Approximate
Deeth (ft) Instrumentation*** Pureose
60 01!flne Jltratigraphy~ check
on seismic line picks,
material sampling.
125 e SP FP Same as above.
110 5P FP Same as above.
75 SP Same as above.
125 FP Same as above.
125 SP FP · Same as above.
110 SP FP Same as above.
120 FP Same as above.
75 Same as above.
75 SP FP Same as above.
175 Same as above.
60 SP FP Same as above~
9C Same aa above.
70 Same sa flbove ..
60 SP Same as above.
100 SP Same· as above ..
1,555 SP = 9 inr dllations, allow 1 miscellaneous
installat.1on.
FP ~ 8 installations, allow 2 miscellaneous
inotalltions.
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BORRO ..
PROPOSED FY83 >W . S!Tl'~ E .. . EXPLORATION
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CONTACTS:
·--. t.IATER!AL LIMllS
BOREHOLES AN
\6.'1AH"El 198 ·. D TEST PITS •
•tH. 197:• AAl AUGER BORING
111111 . . . . ' COE BACKHOE
.'tJP-F.3 19 81 TEST PIT 'W4(13 • Ml BACKHOE G eo• . . . TEST PIT
· ·"" flHYSlCAL . . .
h.!l\t"lt SEISM!<: ~~RVEYS~ ~"'. . . TURNING cfrif~ION SURV£'(· ..,."·~ 1
97
., . . . . POINT · .,,SHANNON SL.aCI~9 t9e0•81 . . , a WI~SOK • ~OOOWARO-
PROPOSEO 80. . . CI.YOE ~.
QHt>-A REHOLESo IANTS
. HA.\1MER DRILl. B"'"' vniNG
0
SCALE ~pa~~<4SOO;.;;~s . -----00 fEET I
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6 -LABORATORY TESiiNG
(a) General
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 routine soil tests to
include:
-Gradation;
-Hydrometer;
-Mo:i sture;
-Atterberg limits; and
-Proctor ..
The more so phi st~cated tests wi 11 be performed by outside 1 abor.atories as
required •
(b) Damsite
1\s discussed in Section 2, petrographic analyses will be performed on spec-
imens of rock and shear material obtained during geo1ogic mapping activi-
ties. While petrologic rock type identlfication in slab section will suf-.
fice for delineation of the different rock types, full thin section petro-. .
graphic analysi.s may be required for samples taken in contact or shear
zones,, The greater detail of the thin "Section identification can provide
va1uab1e 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 will be taken from outcrops and from core drilling 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 usin~f a hammer drill. Limited spoon and barrel
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· samp 1 ing wi 11 be performed, but a majority of the sampling wi 11 be re-
trieval of air-educted alluvium through use of a cyclone separatorlt The
estimated number of samples and routine tests to be performed on these
sarnp 1 es at'"e shown in Tab 1 e 7.1
More detailed tests to be performed on undisturbed and other material
samples will be undertaken following Phase II activities when an under-
standing of the subsurface materials in the damsite has been determined.
(c) Relict Channels/Borrow Site ll
The material properties in the relict channel areas are of signific~nce
both ·to the geologic understanding of the areas and to evalu~tion of the
long-.term _stability of the area. The Fog Lakes Re·l ict Char:~el geologic
mapping may produce a limited ntJnber of bagged samples of alluvial deposits
from face exposures, which will .be submitted to standard sieve and hand
specimen descriptive analyses for general identification purposes. No
detailed material testng is ;:>lanned for the FY83 period in the Fog Lakes
Re 1 ict Channe 1.
The materia? testing program in the Watana Relict Channel will be condueted
in conjunction with the Borrow Si~~ D testing. The principal objective of
the Phase I work is to identify an~ define the type and extent of strati-.
graphic units in the Borrow Site D and the relict channel. Therefore~ the
soils testing program during Phase I wi !1 be limited to routin~ tests as
shown in Table 7.1. Undisturbed and samples takr;n during this phase will
be stored w1t i 1 data interpretation has advanced to the leve 1 where a
sophisticated material testing program can be pl,,nned. However, the tests
that may likely be undertaken for the relict cham;el and Borrow SiteD
are·:
-Relict Channel
• Permeabi 1 ity;
• Consolidation.;
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• Dispersion;
• Strength/density testing; and
•
11 ln-situu triaxial strength.
-Borrow Site U
• Remolded permeabilitj;
.. Dispersion;
• Triaxial strength on remolded material;
• Dilation (dynamic);
• Dynamic shear strength;
• Freez-thaw; and
• Thermal properties.
It is expected that the detailed testing program will be .prepared after
Phase I activities.
(d) Borrow Site E
Because this area is intended for use as concrete aggregate, filter, -and
shall material, a number of tests may be run after the completion of the
winter program, as shown on Figure 7.1. Because the material is scheduled
for processing, in-situ properties such as moist'ure, strength, and density
will not be sampled to a significant extent. However, extensive samples
obtained during the drilling program wi11 be run for gradations-= A few
representative hydrometers will be performed to provide typical data on
settlinr times and water quality effects of the fines in washing and pro-
ce.ssing operations. Other sophisticated laboratory testing that may be run
on composite samples are:
-Su 1 phat·e-soundness;
-L.A. abrasion;
-Freeze-thaw;
Soundness (wetting-drying);
Procto: compaction;
-Density-strength testing; and
-Bulk perme.abil ity after washing.
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7 -RESULTS OF PHASE I INVESTIC~ATION ~~~~--~~~----~~.~~--~
As previously specified, the majority of data reduct ion fo,r the FY83 program
will be performed·in the field. This will allow use of the data in ~coping the
subsequent phases of study. The Phase I data wi 11 be used to update and refine
'
those ge;Jlog·ic and geotechnical interpr~tations presented in the Feasibility
Report·and the 1980-81 Geotechnical Report. As additional data becomes avail-
able, addendums to these reports, reflecting this new data.~ will be prepared as
required·. Finalizat·ion of those addenda are not anticipated until November.
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TABlE 7.1: ESTIMATED fY83 FIELD lABORATORY TESTING
NO. Of :;sample type Tea~ 1ng lfet: ·~to fctn' '•'
Source HoJ~.i Gradation Drl.vett:ore (;ycjone liradatlon !iY'!rometer MolStLTe Atterberg Proctor Future Tesf!-ii)'W -. . ser1es
Stm111er 1.982: (Model -& Stan-
fog lakes derd)
Relict Channel 0 t:i 0 0 15 15 5 5 0 15
" Wat ana Relict
Channel 24 10 BOO 0 200 50 50 50 0 100
&
Borrow Site 26 20 850 0 200 100 100 100 5 100
Winter 1982-83:
Oamsite River I Alluvitlll 20 -100 220 200 20 0 20 5 50
Watana Relict ·. Channel 9 0 200 300 150 25 50 50 5 100 &
Borrow Si.tt.: 5 0 150 300 150 25 150 150 20 100
Borrow Site E 16 100 300 200 20 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 H.l is the proposed schedule for FY83 Geotechnical Program. Key mile.-
stone dates to ensure performance of the work specified in Sections 2 through 5
are 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 foundation. Therefore, to accomplish this, a contract for Phase I work must
be in place by the 2nd to 3rd week of June. The contract for the hammer drill
must be let by September to allow adequate time for mobilization of the equip-
~
ment to the site.
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TASK
2
3
4
5
6
7
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1
DESCRIPTION
CONTRACTS
PHASE!
DRILLING
SEISMIC REFRACTION SURVEY
PHASEn
DRILLING
SEiSMIC REFRACTlON SURVEY
PHASE m
WATANA RELICT CHANNEL
GEOLOGlC MAPPlNG
~
AUGER DR!LLING 8 INSTRUMENTATION
HAMMER DRILLING S INSTRUMENTATION
SEISMIC REFRACTION SURVEY
BORROW SITE D
GEOLOGIC MAPPING
AUGER DRlLLING 8 INSTRUMENTATION
HAMMER DRILLiNG S J"'1STRUMENTATION
1 MAIN DAM SITE
GEOLOGlC MAPPING
I
LOCATE SURVEY CONTROL POINTS"
CIVIL STRUCTURES
GEOLOGIC STRUCTURES
HAMMER DRILLING {RIVER BED)
CORE BORINGS (ABUTMENTS}
SEISMIC REFRACTION SURVEY
FOG LAKES RELICT CHANNEL ·
GEOLOGIC MAPPING
SEISMIC REFRACTION SURVEY
BORROW SITE E
HAMMER DRILLING ~ lNSTfWMENTATfON
I suRVEY CONTROL
SET UP MAPPfNG GRID POINTS
LOCATE SEISMIC LINES
LOCATE DRILLHOLES
. '
SUPPLEMENTAL REPORTS
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JUN JUL I
0 2 4
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PHASE I
AUG .I SEP OCT
6 8 lO 12 14
f I I f
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18
FY83
NOV I DEC
:!0 22 2:4 26 . .
{
NOTICE .TO BIDDERS 7 tv'"' "'F. · I r----r ".GQT :: ... ,.. -
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t ~. l ~ SUPP. REPORT PHASE. I
GEOTECHNICAL SCHEDULE
TASK !l FY 83
..
-') I
JAN: l
28 30
SURVEY
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ORtLLlNG
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PHASE :n:
I MAR
34 36
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APR
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PHASE :IIr
MAY
44 46
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JUN
48 50
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~ SUPP. REPORT PHAsE n T I
FIGURE SJ