HomeMy WebLinkAboutBradley Lake Hydroelectric Power Project Geotechnical Studies 1983CONSULT ANTS
William L, Shanr>on, P,E
Stanley D Wilson, PE :111
SHANNON 8.. WilSON, INC.
Geotechnical Consultants
2055 Hill Road, P.O. Box 843 " Fairbanks, Alaska 99707 ~ Telephone (907) 452-6183
September 30, 1983 K-0631-61
Stone & Webster Engineering Corporation
Bradley Lake Project Office
P.O. Box 14359
Anchorage, AK 99501
Attn: Mr. J.J. Garrity, Project Manager
RE: FINAL REPORT ON GEOTECHNICAL STUDIES, BRADLEY LAKE HYDROELECTRIC
POWER PROJECT, CONTRACT NO. 14500.09-G004S
Gentlemen:
Attached is our final report describing the findings of Shannon &
Wilson's geotechnical studies for the Bradley Lake Hydroelectric Power
Project. This report includes the results of our reconnaissance geologic
mapping program of the tunnel alignment, and our subsurface explorations
the int~ke structure~ powerhouse, and barge basin locations, as well
as at the tunnel alignment crossings of the Bradley River and Bu11 Moose
Fau1 Laboratory test results on soil samples from the barge basin
location are also presented.
If you have any questions, please contact us at your convenience.
Sincerely,
INC.
n9 Geology
~1anager
Encl.
Rohn D. Abbott, P.E.
Vice President and Manager
Seattle 0 Spokane 0 Portland • Fairbanks • 51. Louis • Houston
Table 1
Table 2
Table 3
Figure 1
Figure 2
Figure 3
Figure 8
Fi gures 9-11
Figure 12
Figures
Figure 16
Figure 17
Appendix A
Appendix B
Photos 1
Photos 7-11
LIST OF ATTACHMENTS
Summary of Subsurface Explorations
Description of Rock Classification Methods
Summary of Laboratory Test Results
Location Map
Geologic Maps
Boring Logs
Test Pit log
Grain Size Gradations
Unconfined Compression Test Results
Triaxial Compression Test Results
Plasticity Chart
Summary of Test Resu1ts
Annotated References
Glossary of Cataclastic Terminology
Selected Core Photos
Selected Site Photos
INTRODUCTION
1.1 Purpose and Scope
Stone and Webster Engineering Corporation~ under contract to the Alaska
Power Authority, is currently performing a sibility Study for the
Bradley Lake Hydroelectric Power Project. Shannon &. Wilson, Inc. was
retained by Stone & Webster to perform selected geotechnical studies
related to the project. This report summarizes the results of Shannon &
Wi 1 son fi s stud; es, whi ch were performed under Contract No. 14500.09-
G004S 7 dated April 28, 1983.
Shannon &. Wilson's studies were directed at evaluating geologic
conditions specifically at the location of the proposed intake
structure, along the power tunnel alignment, at the proposed powerhouse
location, and in the vicinity of the proposed barge basin. This work
was accomplished through a reconnaissance level geologic mapping program
and the drill ing, sampling, and logging of exploratoy,y borings at four
locations. A fifth boring which had been planned to confirm the depth
of bedrock at the location of the proposed powerhouse was replaced by a
test pit because of the shallow depth of the overburden. Pertinent
previous reports were reviewed during the course of work.
The purpose of the geologic mapping and subsurface exploration at the
intake structure and powerhouse sites was to identify conditions which
might affect the design or suitabi1ity of the layout now being
considered. Geologic mapping along the tunnel alignment was performed
primarily to estimate the amount of various rock types that would be
encountered along the alignment. Exploratory borings were drilled
the tunnel crossing of the two major identified faults in the area to
investigate the nature of the rockmass and the character and thickness
of any gouge zones in the faults. The boring at the barge basin
location was drilled to determine if the nature of the tidal flat
deposits was such that stabil ity problems woul d affect the proposed
basin development. To assist in this determination, a soil laboratory
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testing program was added to Shannon & Wilson's scope of work to define
the properties of the soils from that boring.
The scope of Shannon & Wilson's geotechnical studies speci cally did
not incl relogging of core from previous borings; rock joint surveys;
pressure or permeabi1 ity testing of bod ngs; invest; gat; on of geo log; c
conditions at the dam site, quarry sites, or for the roads or other
adjunct facilities; testing of the rock COre obtained from the bar;
or studies of seismic or other geologic hazards.
1.2 Limitations
This report was prepared for use by Stone & Webster Engineering Corp-
oration, the Alas Power Authority, or their consultants, and presents
the results of surface and subsu geologic explorations at a limited
number of specified sites for the Bradley lake Hydroelectric Power
Project. The geologic conditions in the proj are~. are complex and
variable~ and the reconnaissance level geol ic mapping and drilling
program performed may define the entire range of conditions which
might be present. In addition, surface geology and conditions found in
relatively shallow borings may not be wholly representative of con-
ditions at tunnel depth. While this report is not a comprehensive study
of the geology of the Bradley Lake proj area 9 it should provide a
basis for estimating conditions in the specific areas investigated.
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3. FIELD EXPLORATIONS
3.1 General
The fi d explorations for Shannon & Wilson1s study of the Bradley Lake
Hydroelectric Power Project were accomplished during the summer of 1983
in two separate phases, geologic mapping and subsurface explorations.
Geologic mapping was conducted from June 6 to June 16 by Dan Clayton of
Shannon & Wilson and Paul Mayrose of Stone & Webster Engineering Corpor-
ation. Boring locations for the subsequent drilling program were
selected after that reconnaissance. Results of the geologic mapping
effort are presented in section 5 of this report.
Subsurface investigations were accompl ished from July 5 to August 20.
Three diamond core boringS$ ranging in depth of h.ole from 155.3 to
262.3 feets were drilled along the tunnel alignment for a total drill
footage of 623.9 feet, including 63 feet of soil drilling and 1 feet
of rock drilling. The cored holes were drilled at an inclination of o
to cross the predominantly vertical geologica1 structure typical of the
project area, and to intersect and determi ne the hor; zonta 1 extent of
suspe::ted shear zones. A fourth boring was drilled to a depth of 50
feet in the area of the proposed barge basins and was advanced using
soil sampling techniques.
In addition to the four borings, a test pit was dug by hand in the area
of the proposed powerhouse, in lieu of an additional boring, to verify
the presence of shallow bedrock at that location. Drilling operations
and geologic conditions were logged by experienced geologis from our
firm. The first three borings were logged by Roger Troost, and the test
pit and fourth boring were logged by Dan Clayton.
Daily transportation of personnel and movement of drilling equipment was
a~complished by helicopter based out of Homer.
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3.2 Geologic M~ing
The geologic mapping was focused speci cally on the intake structure~
tunnel and penstock alignment~ and powerhouse site for the Bradley Lake
Hydroelectric Project. The purpose of this study was: 1) to identify
conditions which might affect the design or suitability of the layout
now being considered; 2) to map and describe the geologic un; and
structural features in the vicinity of the intake structure, along the
tunnel alignment, and at the powerhouse site; 3) to estimate the amount
of various rock types that can be anticipated along the tunnel
alignment; and 4) to determine locations and orientations of borings to
be drilled as part of Shannon & Wilson's studies.
The geologic studies consisted of three main sks; 1) a review of
previous geologic work; 2) ogie mapping of the intake~ tunnel
alignment, and powerhouse sites; and 3) photogeologic interpretation of
the project area.
The review of previous work was accomplished prior to the other tasks.
Both project-specific geologic reports and geologic studies of more
regional significance were reviewed. Those studies which included
information pertinent to this evaluation are identified in an annotated
list of references in Appendix A. The scope of work did not include
sufficient time to field check the geologic maps or joint studies of
previous workers, except where their studies overlapped with the present
mapping program. Nor was there time to carefully inspect the rock core
from previously drilled borings.
The geologic mapping was accomp1ished by foot traverses roughout the
intake and powerhouse areas and along the tunnel alignment. t~app;ng was
done on 1: 2400 U .S~ Army Corps of Engineers topographi c maps, Map
locations were determined by compass triangulation from known locations
supplemented by altimeter readings.
The photogeologic interpretation of the project area was conducted
concurrently with the geologic mapping task. Photogeologic mapping was
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accomplished during the evenings and when i ement weather prohibited
helicopter access to the site. Stereo pairs of 1:12,000 black a white
aeri a 1 photographs and a stereoscopic vi ewer were used for the photo
i rpretation. The photos were most useful for identifying structural
features and lineaments, but also aided in determining the distribution
of geo 10gic units. Photogeologic interpretations were field checked as
part of the geologic mapping task.
The primary focus of the geologic mapping k was to develop a geologic
map of a 200-foot-wi corridor along the proposed tunnel alignment and
of the intake and powerhouse s Has. Where bedrock along the tunnel
alignment corridor was obscured it was necessary to map adjoining areas
in order to interpret the characteristics of the lithologic units along
the alignment. Adjoining areas were also briefly examined to
understand the structura1 features and 1; that trend through the
project area. The scope of work for the study did not include geologic
evaluation of the dam site or of potential quarry sites.
Following completion of the field work, petrographic thin sections of
several rock samples were prepared and examined microscopically by Paul
Mayrose of Stone & Webster Engineering Corporation. The results of this
work were relayed informally to Shannon & ~Ji1son and have been incorp-
orated into this report where appropriate.
3.3 Subsurface Exploration Program
Three diamond core borings, S\tJ 83~19 ~2, and -4, were drilled in the
vicinity of the proposed intake structure and the proposed tunnel
alignment crossings of the ey River and Bull Moose faults 3 respec-
tively. A Longyear 38 drill rig, adapted for helicopter transport~ was
u to dri 11 the three angl ed di amond core holes along the propos~d
tunnel alignment. Using water from nearby lakes as a drill flu;d~
the holes began at the surface using an HQ 3 triple tube wireline core
barre19 which yields a core diameter of 2.38 inches. The wireline
system allowed relatively trouble-free advancement of the core barrel
through fractured rock and other caving materials, and the triple-tube
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19n facilitated recovery of highly fractured materials in a rela-
tively undisturbed state. v.!hen it became necessary, the coring system
was reduced to NQ 3 s1 coring apparatus, recovering a smaller di
core of 1.78 inches. Both size coring sys used five-foot long inner
barrels.
When drilling action suggested zones of rna rials that could not be
suitably recovered with an internal discharge bit, a five-foot long NWD 4
conventional core barrel (core diameter of 2.06 inches) with a face
discharge bit was used. This minimized the exposure of fragile sil or
clayey materials to the water used as a drilling fluid, in order to
improve core recovery.
Generally the core runs were photographed while still in the split
innertube to record the natural state of the material as first obse
in the field. Photographs were also taken each box of core.
ected core photographs are included at the end of this report. A
comp 1 ete set of core photographs has been prov; to Stone & Hebs
Eng; ng Corporation for reference.
The Rock Quality Designator (RQD) was measured on each run of rock core
while still in the split innertube, using the method of Deere (Table 2).
Values of RQD are recorded on the boring logs, Figures 3, 4, and 7. It
should be noted that because of the different sizes and styles of coring
systems used that it may not be possible to directly correlate ROD from
one run or boring to another. Occasional instances of dri11
IIchatter" or vibration, or 'instances of "mudding" of the coring bit, may
also have caused mechanical breakage of the core, locally reducing the
RQD.
In general s core recovery was excellent for all three diamond core
borings, averaging 99% for the total 561 feet rock drilled. Loss
dri11ing water was minimal. No pressure , permeability tests, or
other in situ testing were performed in the core borings.
9
11ing techniques and geologic conditions are summarized on the boring
logs~ Figures 3, 4 and 7.
The boring performed at the proposed barge basin, SW 83 ,was advanced
using rotary wash techniques with a Simco 2400 drill rig. Samples were
obtained the base of the advanced casing with either a 3" 0.0.
thin-wall sampler (Shelby Tube), or a 211 0.0, split-spoon sampler driven
by a 140-pound hammer fa 11 i ng 30 inches onto the dri 11 rods (Standa
Penetration Test), For the split-spoon samples, the number of blows
required advance the sampler the final twelve inches is the pene-
tration resistance, which indica the relative consistency of fine-
grained soils and the relative density of granular soils. Torvane shear
tests and pocket penetrometer tests were performed on the end of each
Shelby Tube sample in the field.
In addition to sampling of Boring SIN 83-3~ vane shear tests were
performed at two depths in fine-grained material. shear strengths
were first obtained for the undisturbed material and the remolded
strength was determined following 10 revolutions of the vane. The
results of all eld measurements are presented on the summary baring
log for SW 83-3~ Figure 5, and are summarized wi laboratory test
results on Figure 17.
An additional shallow boring, numbered SW 83~3A, was drilled adjacent to
Boring SW 83-3 specifically to obtain Shelby Tube samples from zones of
fine-grained material not adequately represented in the sampling inter-
val of Boring SW 83-3. The log of this boring is presented on Figure 6.
All of the samples obtained from the barge basin location were sealed
and returned to our Fairbanks office for laboratory ng.
Because of the di culty which would have been involved in setting up
dri 11 rig the proposed powerhouse location, and because of
shallow depth of the overburden, a test pit was dug at this 1(1cation,
The pit was dug by hand, beg; nni ng at an exposure of rock on the hi 11
Side, and eventually exposing the rock surface about 2 feet below the
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colluvial soils over an area about 9 feet square. The log this test
pit is presen on Figure 8.
The preliminary locations selected for exploratory borings during the
geologic reconnaissance work were surveyed for horizontal location and
elevation by R & M Consultants. In the case of all three core borings,
the actual boring location was shifted from the surveyed location to
enhance the quality of subsurface information, Actual core boring
locations were determined by tape~ compass and hand level from the
survey maker. During the course of the exploration program, the
proposed location of the barge basin was shifted from the south side of
Sheep Point to the north side. The boring location was shifted accor~
dingly, and the approximate location of the boring was established by
triangulation referenced to features on the Corps of Engineers 1 :2400
scale topographic base map, . The coordinates and elevations given for
each boring on the individual boring logs should viewed as approx-
imate, given the limitation of the locating methods involved. All
elevations are referenced to the Bradley Lake Project Datum.
The boring locations are shown on the Location Map,
appropriate sheet of the Geologic Maps Figure 2.
garrling the borings is summarized in Table 1.
Figure 1, and on the
Pertinent data re-
The classification
methods used to describe rock p'roperties such as hardness and weathering
are described in Table 2.
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4. LABORATORY TESTING
4.1 Soil Tests
Laboratory testing was perfonned only on soil samples obtained from
boring SW 83 .. 3 9 located in the vicinity of the proposed rge basin.
The primary purpose of this testing was to establish the index and
engineering properties of the tidal flat deposi ,particularly their
sensltivity, to determine if the stability of the proposed basin
development would be affected. No laboratory testing was rformed on
the overburden soils from the diamond cored borings.
Index property test; ng on both disturbed and undi sturbed sampl es con-
sisted of determination of water content, grain size gradation (by both
mechanical and hydrometer analyses), specific gravity, Atterberg limits,
pore water sal i nity, and organic content. Uni t weights were determi ned
only on undisturbed Shelby Tube samples.
Engineering property testing consisted of performing unconsolidated-
undrained triaxial compression tests on both undisturbed Shelby Tube
samples and on remolded samples for the purpose of determining the
sensitivity of the materials. Remolding was accomplished by disag-
gregating the sample by forcing it through a #4 sieve, followed by
recompacting in a mold to approximately the unit weight and moisture
content of the natural sample.
A pa i r of unconf'l ned camp res s ; on tes ts ( und i rbed and remo 1 ded
samples) was so run. Laboratory Torvane tests~ both natural and
remOlded, were also run where possible to obtain additional shear
strength values. The remolded strength was measured after 8 to 10
revolutions of the Torvane.
Labor.atory tests were performed in accordance with app 1i cab 1 e ASTM or
other generally accepted 1 aboratory procedures. Water added to samples
for determination of Atterberg limits was a solution of Sodium Chlori
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approximating the salinity of the natural pore water of the sample.
Another modification to standard procedures was the application of back
pressure to the unco~solidated-undrained triaxial test samples after the
application of the confining pressure. This was done to prevent
consolidation in the event the samples were not saturated when received
in laboratory.
The laboratory test results are summarized on Table 3, Summary of
Labonatory Test lts. Grain size gradations are plotted on Figures 9
through 11~ compression test resul are plotted on Figures 12 through
15, and Atterberg limit values are plotted on the Plasticity Chart,
gure 16.
The soil properties and test resul from Boring SW 83-3 in the proposed
barge basin area are summarized and discussed in sections 6.6 and 7.5 of
this report. laboratory data relating to the sensitivity of the
material are summarized in Figure 17.
our knowledge, no soil tests on samples of the tidal deposi have
been reported in previous investigations.
4.2 Rock Tests
With the except; on index property tests performed on a sample of
gouge material from the Bradley River Fault from Boring SW 83-2 $ no
other tests were performed by Shannon & Wilson on rock from the diamond
core borings, as this was outside the scope of the present study. Water
content, Atterberg limits, and grain size gradation were determined on a
sample of gouge from the Bradley River Fault. Results of the first two
are shown at the beginning of Table 3, and the grain size gra-
dation is plotted on Figure 9.
Tests on rock core were performed by the U. S. Army Corps of Eng; neers
and reported in Appendix 0 of Genera1 Design Memorandum No.2. These
ts consisted prima ly of unconfined and triaxial compression tests 9
and spli ing tensile strength tests.
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During the present Feasibility Study, Dr, Alfred Hendron~ under contract
to Stone & Webster Engineering Corporation, rformed additional tes
on rock from the Corps of Engi neers I bar; ngs, These tests consisted
principally of unconfined compressive strength; Schmidt, Shere, and
Abrasion Hardness; and longitudinal wave velocity.
A brief discussion of the results of these rock tests by others is
contained in Section 7 of this report. We understand that at least two
manufacturers of tunnel boring machines have also tested portions of the
Corps of Engineers' rock core~ but we have not reviewed the results
these tes
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5. GEOLOGY
5.1 Regional Geology and Tectonics
The portion of the Kenai ~1ountains in which the Bradley Lake proj
area is located is composed of metamorphic rocks of upper Mesozoic Age
named the McHugh Complex (Clark~ 1973). These rocks are thought by
Clark and others to have been deposited in deep water on the continental
margin. The rocks have been uplifted§ deformed~ and shaped by erosional
processes. Accentuated by glacial and col1uvial influences, the local
topography is dominated by conspicuous lineaments that are surficial ex~
pressions of a complex network of faults or major joint that are
resultant of the activity of the seismic region in which the area lies.
An expression of the primary tectonic influence on the project area is
found in the Gulf of Alaska, where, about 185 miles southea of Bradley
Lake t the axis of the Aleutian Arc-Trench occurs sub~parallel to the
prevalent northeast~southwest strike of the prominent tectonic features
found around Bradley Lake and in the surrounding region. The
convergence of the North American and Pacific lithospheric plates,
marked at the earthls surface by the Aleutian Arc-Trench, is responsible
for substantial regional .tectonic activity as a result of the northward
movement and underthrusting of the Pacific Plate at the rate of about 6
em per year. The resultant subduction zone of this regional megathrust
system dips to the northwest from the Aleutian Arc-Trench, and a plane
of seismic activity, called a Benioff Zone t marks the bourdary of the
two colliding lithospheric plates. lhis Benioff Zone is the focus of
several historical earthquakes in Southern Alaska, and at project
area occurs about 30 miles below the earth's surface.
The immense compressional forces generated by the plate tectonics of the
Kenai Region have resulted in deformation of the upper cru materials
of the Kenai Peninsula in the form of folding, jointing and faulting.
Of the several major regional fault systems that express this defor-
mati on 9 two faults are found in the vi ci nity of the Bradl ey Lake
K-0631-61
Hydroelectric Power Project. The Eagle River Fault crosses through the
southeastern portion of Bradley Lake, and the Border Ra~ges Fault forms
the northern front of the Kenai Mountains and flanks the northwest
portion of the project area. Neither of these faults crosses the
project area but their proximity suggests a relationship and possible
i nf1 uenee on two other 1 esser, but st i 11 pronounced ~ fau lts that do
cross the proposed tunnel alignment, the Bradl River Fault and the
Bun Moose Fau1t~ found 3,900 feet and 9,800 feet, respectively, from
the proposed intake area at Bradley Lake.
L ike the Eagle River and Border Ranges Faults g the Bradley River and
Bun Moose Fau1ts strike in the general northeast-southwest direction
that is characteristic of the regional tectonic grain, and they have
been suggested to be splays from the Border Ranges Fault (Woodward~Clyde
Consultants~ 1979). Together with several other randomly oriented
faults, these lineaments create the topography found in the Bradl lake
project area.
The tectonic processes discus above have also been responsible for
the pervasive shearing of the rockrnass itself, which is discussed in
greater detail below and in section 6, Subsurface Conditions.
5.2 Seismicity
Shannon & Wil son I s scope
project site seismicity.
Woodward-C1yde Consultants
of wo rk di d not inc 1 ude an eva 1 uati on of
This subject was considered in depth by
(1981), and is summarized by the U.S. Army
Corps of Engineers in General Design Memorandum No.2.
Briefly summarizing this previous work, the Corps of Engineers selected
two design earthqua a magnitude 8.5 event occurring on the
megathrust beneath the site, and a magnitude 7.5 event ocurring on the
Border Ranges or le River Faults. Studies by WOOdward-Clyde Consul-
tants indicated that these latter two faults dominated the response
spectra for the design maximum earthquake.
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None of the Border Ranges~ Eagle River, Bradley River, or Bull riJoose
Faults are known to be historically acthe according to the
t'/oodward-Clyde report. r4icroearthquake data available at the time of
the report revealed no association between the recorded seismicity and
the mapped faults in the project area. In fact, the seismic activity
appeared to be at a depth shallower than the subduction zone, defor~
mation along which is thought to be the primary cause of motion on these
faul ts. S, nce the Woodward-Clyde study in 1981, we understand that
,evidence has been found to suggest recent activity on the Eagle River
fault near Eklutna, some 125 miles northeast of the project si
If the Border Ranges or Eagle River Faults are active, Woodward-Clyde
concludes that displacement on either of them could induce movement on
the Bull Moose or Bradley River Faults, or on other small faults in the
project area. In addition, they state that independent fault rupture
appears possible on the Bradley River or Bull Moose Faults, with amounts
of slip ranging from 20 em to 300 em. They estimate the probability of
displacements occurring on these faults in the next 100 years in the
range of 4 X 10-3 to 2 X 10 -4.
Woodward-Clyde Consultants report that data on the Border Ranges, Eagle
River, Bradley River, and Bull Moose Faults is generally scarce. They
suggest that further detailed geologic studies would be required if it
becomes necessary to further quantify the dominance of the site response
spectra by the first two faults, or to more precisply estimate the
potentiai for surface rupture along the two on-site faults.
5.3 Site Geolo~
5.3.1 General Geologic Setting
The project area is underlain by weakly metamorphosed sedimentary strata
of the McHugh Complex. This bedrock is locally mantled by
unconsolidated glaCial 9 alluvial, and colluvial deposits and 1 below tree
lines~ is generally obscured by vegetation and soil cover. The
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McHugh Complex in the project area is comprised primarily of weakly
metamorphosed graywacke, argi 11 i te ~ a cherty argi 11 i te. Loca l1y
these rocks are intruded by da dikes. A metaconglomerate has been
described in previous geologic, studies of the Bradley Lake area~ but
was not observed in the area of the proposed tunnel alignment 9 power-
house, and intake*
The graywacke~ argilli and cherty argillite of the McHugh Complex
have a complex distribution as a result of their intense deformation
and structural juxtaposition. Recognizable bedding planes and marker
beds are generally absent or masked by tectonic foliation~ making
individual units very fficult to map. Many contacts appear to be
tectonic rather than depositional, and individual lithologic units
commonly are discontinuous over short distances. Many of the thicker
lithologiC units either pinch out or are truncated within a few hun-
df~ed feet along their trend, whereas the thinner units often can be
traced no more than a few feet to few tens of feet. Consequently,
proj ion of lithologic units and rockmass characteristics from sur-
face exposures laterally jnto areas where the rock is obscured and
vertically into the subsurface is necessarily specu1ative.
The rocks in the Bradley Lake area are predominantly catacla ic rocks
that have been broken and granulated due to stress and movement during
faulting. These broken rocks have nerally regained cohesion through
low-grade met amorphi sm. The defonuat ional hi story of the rocks
explains t r sheared texture, intimate intermixing~ and the often
extremely gradational contacts. However, lithol c classifications
were used during the geologiC reconnaissance, rather than cataclastic
nomenclature, for consistency with previous investigators.
5.3.2 Lithologic Units
For the purpose of this evaluation we have subdivided the bedrock into
five lithologic units based on their di inctive rockmass properties.
These units are graywacke, massive argillite, foliated argi11ite 3
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foliated chertyargi11i »and da te intrusilJes~ The general char-
acteristics of these bedrock units are discussed belowo
The graywacke is a highly indurated, dark gray to dark greenish gray~
very fine to medium-grained, weakly metamorphosed sandstone. It
typically contai ns da rk gray, angul a r to sub rounded, sand-s i zed rock
fragments that, in hand s mens ap r to argilli or sl
The graywacke grades in grain size the massive argillite described
below. In the finer grained samples lithic fragments generally were
not observed. Fine irregular quartz and calcite veins are locally
common in the graywacke.
The graywacke is massive wi th 1 i ttl e or no evi dence of beddi ng except
for lenses or detach remmants of beds of foliated argillite and
cherty argillite that locally occur within the unit. Although com-
monly slickensided, the graywacke in hand specimen and outcrop does
not reflect the pervasive tectonic fabric that is strongly expressed
in the foliated argillites. The graywacke is relatively resistant to
weathering and generally .underlies the more prominent hills in the
proj area. Where exposed~ the rock is fresh to slightly weathered.
Moderately to widely spaced. partly opened to very tight joints are
typical of the vertical exposures of the graywacke.
The massive a l1ite is a strongly indurated, dark gray to dark
greenish gray, weakly metamorphosed siltstone to very fine-grained
sandstone. It is a fine-grained equivalent of the graywacke and has
similar rockmass properties. Exposures of this unit are fresh
slightly weathered~ massive, lack dence of shearing or foliation in
hand specimen and outcrop~ and typically have moderately to widely
spaced joints. The massive argillite occurs in juxtaposition with
both graywacke and foliated argilli Chert is noticably rare in the
massive argillite, but in other respects this lithologic unit appears
to be the relatively unsheared equivalent of the foliated argillite.
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A weakly metamorphosed tuff was identified in a thin section from a
sample taken from a location just northwest of hill 2036.3. In hand
specimen this rock resembled a metamorphosed mafic intrusive, but in
outcrop it appeared to grade into massive argillite. Tuff was also
identified in a thin section of a sample of graywacke taken from a
location midway between hill 2036.3 and the surge tank. Even at the
microscopic level) the tuff appears to be intermingled with graywacke
and/or argillite. The texture of the tuff is s stive of depOSition
in a water medium. These observations suggest contemporaneous depo-
sition of the various parent materials. a situation compatible with
the geologic setting. The Corps of Engineers classified a thin sec-
tion sample from their boring DH-ll as a "volcanic graywacke". s
occurrence is not noted on the log of that boring. Considering the
appearance of the material in thin section, this term may, in fact, be
more accurately descri pt1ve of its origi n than is the term "tuff!!.
It is difficult to accurately determine regarding tne distribution of
the tuff cause it can only be posi ve1y identified in thin ion.
It appears to be present . withl n bot h the graywacke and the massive
a rgi 11 i teo Al though i presence has been confi rmed only in the area
between hill 2036.3 and the proposed surge tank location, this may be
a coincidence of locations from which thi n sect ions were made and
areas with abundant exposed rock. Because the tuff was not fferen-
tiated in the field reconnaissance, it is not indicated or referenced
on the geologic maps.
The foliated argillite and foliated cherty argillite are differen-
tiated solely on the abundance of chert within the rock. For this
evaluation we have considered the argillite to "chertyll if i nter-
layered and lenticular chert exceeds about 10 percent of the outcrop.
The argillite is a dark gray to blacks weakly metamorphosed siltstone
and very fine sandstone. Chert occurs throughout the rock (in various
percentages) typically as discontinuous layers and elongated nodules
up to a few inches thick and occaSionally up' to one to two feet thick.
In a few instances~ discontinuous, fractured chert layers as thick as
20
K-0631-61
10 feet were observed within the foliated argilli Chert layers and
nodules lie within the foliation plane, which strikes from N-S to N
20° E and dips steeply. With the exception of the few thick chert
layers described above, the chert generally does not constitu more
than about 20 percent of the rock in anyone location.
The foliated argillite is a highly sheared rock. While the foliation
may conform in neral with relict bedding, it is predominantly a
shear foliation that. has developed along the regional structural
trend. This shearing resulted in the severe fragmentation of the
chert layers and rvasive cataclastic texture of the unit as a whole.
The rock breaks preferentially along a myriad of subparallel fr ures
that coll ively define the foliation plane. Jointing is not fre-
quently expressed in outcrops of the foliated argillites but where
present the joints are typically widely to very widely spaced and very
tight. Linear, soil-covered topographic depressions at various angles
to the fali ian sugge ,however, that jointing may be more prevalent
in this unit than exposures indicate. Outcrops of the foliated
argilfite are fresh to sli.ghtly weathered.
Two dacite dikes were observed in the map area. One is known from a
sing1e small outcrop at the exit portal s whereas the other is exposed
to the east near the middle of the tunnel alignment6 The eastern dike
trends northeasterly to easterly across the regional structural trend.
cutting across both graywacke and argillite unitso It is about 30 to
50 feet wide and can traced to the northeast of the tunnel align-
ment where it dips nearly vertically. Viewed from the air, this dike
appears to bi furcate along i trend although this was not confi rrned
on the ground~ It has apparently been offset about l~OOO feet in a
right la ral sense across the Bradley River fault zone. The dacite
is a light greenish gray, porphyritic rock. It is typically slightly
weathered in outcrop~ and appears to be slightly more resistant to
erosion than the units it intruded. There is no obvious alta ion of
wall rocks resulting from the intrusion, nor does there appear to be
any significant variation between the center and rna ins of the dike
21
K-0631-61
itself. The dacite is a massive rock with widely spaced, very tight
joints. Its rockmass properties to be simi1ar to the massive argil-
1 i te and graywacke $
Unconsolidated deposits in the project area consist of glacial outwash
and till in the vicinity of the proposed intake and locally ong the
tunnel alignment~ tidal flat deposits near the powerhouse site, and
colluvium in the va11eys and on the hillsides throughout the project
area. The 91a a1 deposits, intermixed with colluvium, occupy the
small drainages and bedrock depressions adjoining the Bradley Rivero
These deposits consist of silt~. sand, gravel, and boul rs derived
primarily from the argillite and graywacke~ and probably range from
less than a few feet to perhaps over 20 to feet thick. Colluvial
soils are prominent in the forested areas and on the lower hill slopes
throughout the area. These materials are derived from the bedrock and
contain sand to boulder 51 clasts of argillite and graywacke in a
rna t r i x of s i 1 t .
5.3.3 Structural 6eo1
5.3.3.1 General
The most prominent structural elements in
pervasive~ closely-spaced shear foliation
complex structural distribution of bedrock
plexly deformed by the pervasive shearing,
the
in the
un its.
by two
oject area are the
argi11 i tes and the
The area is com-
major fau 1 t zones,
and by numerous smaller faults in a variety of orientations. The sig-
nificance of folding in the project area is not parent because;
a) well-defined marker horizons and beadi are lacking, b) vegeta~
tive cover obscures much of the rock, and c) the bedrock units are
complexly distributed.
22
K-0631
5.3.3.2 Faults
The Bradley River and Bull Moose faults are the most significant
faults in the project area. These faults zones are high~angle struc-
tures that trend N5°E to N200E and extend for at least a few miles
outside the proj area. These fault zones are described in greater
detail in the discussion of the geologic conditions along the tunnel
alignment. Several smaller high~angle faults and a few low-angle
faults have also been identified in this and previous studies. The
high-angle faults tend to fall into two general sets: those subpar~
a1lel to the Bradley River and Bull Moose fault zones and those
about 90° to these larger structures. Only a few low-angle faults
have been a erved. This may reflect t general absence of these
features~ but is more likely indicative of their poor surface expres-
sion. The low-angle faults that were observed are exposed in cliff
faces»
5.3.3.3 Joi nts
JOinting is present in all the rocKs in the area although it is gen-
erally best developed in the graywacke. Joint orientations are highly
variable, and the joint orientations observed in a given outcrop are
controlled to some extent by the orientation of the outcrop itselfo
Joint surfaces are generally relatively smooth, and range from very
tight to open cracks about 2 inches wide. Where open, the joints are
typically not lied except very near the surface where soil and
organic matter have entered from over1ying soil cover. Joint spacing
is also highly variable, ranging from a few inches in local areas to
several tens of feet in other areas. Gene ly at least three joint
sets at high angies to one another can be found, resulting in a blocky
rockmass$ iled joint descriptions along trans s at the damsite~
powerhouse si ,and intake and exit port s is presented in [JOWL
Engi neers (Janua ry, 1983).
23
K-0631-61
5.3.3.4 Lineaments
Many linear topographic depressions cross the project area in apparent
random orientation. A few of the most pronounced and continuous of
these lineaments are recognized as faults~ but the origins of many of
the others are not readily apparent. Most of the lineaments are prob-
ably the surface expression of either faults, joints, or series of
closely spaced joints where the surface has been differentia11y eroded
by glaciation~ frost action, and runoff along planes of weakness.
Unfortunately rock exposures along the lineaments are commonly absent.
and colluvial or gla a1 deposits obscure the evidence needed to
determine the nature of these featureso Nevertheless, the lineaments
provide an indication of the frequency and extent of the relativelY
larger discontinuities, particularly in the areas lacking extensive
soil and forest covero
5.4 &eol c Conditions -Surface Inve ions ~:.~~--~----------~----~----~----~
5.4.1 Intake Structure
The intake to the power tunnel will be located in the area of the left
abutment. AlthOugh its exact position has yet to be determined it
will be situated in the lowland immediately no h of hil11270.7.
Tni s lowiand area is covered by dense vegetation and an unknown thick-
ness of colluvium shed from the adjoining highlands. The colluvium
may directly overlie bedrock or it may overlie glacial ti11 or outwash
deposits which, in turn., rest on rock.
The adjoining hills provide the best indication the characteristics
of the bedrock that will be encountered at the intake. This rOCK is
comprised of complexly mixed graywacke and foliated argillite with
less than 10 percent chert nodules and layers. The contacts between
the graywacke and argillite roughly parallel the foliation in the
a illite which typically trends N-S to N200E and dips steeply. Hil'l
1270.7 is also cut by several small faults and joint sets. These
24
K-0631-61
features have been described in some detail by Woodward-Clyde (1979)
and DOWL Engineers (JanuarYt 1983) as rt of their investigations for
the left abutment of the dam.
To the north of hill 1270e7 the next bedrock exposure is on a small
knoll that lies near the intake locatione Like the rock to the south?
this exposure consists of a mixture of graywacke and foliated argil-
lite. but is not faulted and does not display the complexity of joint-
ing that can be seen on the north side of hill 1270.7.
The 10wland between hi11 1270.7 and the smaller knoll to the north
lies along an east-northeast-trending topographic lineament that
appears to be the sur-face expression of an east-northeast-trendi ng
rockmass discontinuity. About 1,000 feet to the west of Bradley River
the lineament merges with an east-trending fault mapped by Woodward-
Clyde (1979). D1 rectly east across Bradley River, it trends into the
vicinity of a small covered area which may be the surface expression
of a joint or small fault. The lineament also parallels an east-
trending fault located about 250 feet to the north on the east side of
the river, and a series of lineaments of unknown origins to the south-
west. It also roughly parallels a joint set exposed on the north side
of hill 1270.7. As detailed in section 6&2, a boring oriented to
cross this lineament indicated a zone of very closely spaced joints
and fractures e
5.4.2 Tunnel Alignment
5.4.2.1 General
The tunnel al i gnment eval Ui3ted for thi s study extends for approx;-
rna y 14,050 feet along a N63°W trend from the proposed intake to the
proposed surge tank location. Northwest of the surge tank the align-
ment trends N47°W for about 4~250 feet to the proposed powerhouse
25
K-0631-6!
location. For this discussion the surficial ology along the a1;gn-
ment is described in geologically distinctive segments beginning with
the area closest to the intake portal.
5.4$2.2 Intake to Bradl River Fault Zone
This easternmost section of the tunnel alignment is underlain by
interbedded graywacke and argil lite. Because of their comp1ex mixing.
we have mapped these rock types as a single untt comprised of approxi-
mately 50 to 65 percent massive graywacke and 35 to 50 rcent argil-
11 The argillite is commonly foliated and contains less than about
10 percent chert nodules and thin interbeds of chert. The argill ite
is in gradational and irregular contact with the graywacke. It occurs
as interbeds and pockets that range from less than a foot to as much
as 100 feet thick.
Jointing is more apparent along this section of the tunnel alignment
than farther to the northwest. This apparent abundance of joints may
be part; ly due to the re1atively high reli and steep rock faces in
this area, but the jointing also contributes to the high ief
because many of the cliffs in this area are formed along joint faces.
Several lineaments also cross this section of the tunnel alignment at
various orientations. We sLlspect that some of these features may be
faults, but there is generally insufficient rock exposure to determine
whether they r'epresent faults or major joint sets. One pair of par-
allel lineaments, located about 1.700 feet northwest of the intake
structure is particularly suggestive of a fault zone. These linea-
ments. separated by about 100 feet, trend about NIOoW for about
3,500 feet ong parallel sets of aligned notches and valleys. These
lineaments tenninate abruptly to the south against a fault mapped by
Woodward-Clyde (1979)~ Although this pair of lineaments was mapped by
Woodward-Clyde (1979) as a fault, the origin of the lineaments is
uncertain ,because of lack of exposure. If they are the surface
expression of a fault~ then the zone may contain highly fractured and
26
McHugh Complex melange
Valdez Group
near-trench magmas
Seldovia metamorphlcs
Peninsu~ar Terrane
ultramafic rocks
Cook Inlet Basin
OI)&-$ile&(it 0 0'"
" t,\ /I; Q> e ~ " It ill ~ It-<)
. .
.,eG .... os"'e(jo~(II~Ii'~
.04!l®."Qjf\l$eOIilI'l!$~*,
OlitoeSIi>"'oO~eC80
dI-w4l>e&Re851 Qe "&()
oe-e$Q\8eOfll&G$O
4\I~OO-81eIllG!!III~
fI&*«!octo lieli
$EII!ICeeee
..
(0/\
Chugach Islands
~ ~
o km
Harding
ICGfieia
40
o o
Ii) .....
~------------------59Q--------------------------------------~
GREWINGK GLACiER
~
ES:>
.~
~
CE~tl~2)
dikes
late faults
cover
greenstone
massive graywacke
ribbon chert
o m 100
pebbly mudstone/melange
fed argillite anna _ bl
Figure 8. Sketch map of McHugh Complex melange from the snout of Grewingk Glacier.
Note abundant late faults offsetting early contacts, and note dikes associated with faults.
Mapped by D. Bradley and r. Kusky (unpublished).
WOSNESENSKI LACIER
@1~~~ -----------9 raywacke/argi! lite
limestone blocks E;:~
chert
chert/argillite melange
greenstone melange
200 == :::::::1
crushed rock up to about 200 feet wide along the proposed tunnel
alignment~ which crosses these features at an angle.
5.4.2.3 I)radl River Fault Zone
----~----------------
At a distance of approximately 3,900 feet from the intake the tunnel
alignment crosses the Bradley River fault zone. Two main branches of
the fault are recognized in the vicinity of the proposed tunnel align-
ment. The main trace, which can be followed for several miles along a
trend of about N15°E, occupies the west si of a steep-walled. fault-
controlled valley. The other branch trends northerly thr9u9h the cen-
ter of the vall and me with the main trace just south of the
drainage divide in the valley. Although these faults are mantled by
colluvial and glacial deposits, they are believed to nearly ver-
tical because of their linear topographic expression. Exposures else-
where along the Bradley River fault indicate that the main fault trace
may have a gouge zone of finely pulverized rna rial that is about
50 feet wide, with sheared argillite extending another 50 to 75 et
on either side (DOWL Engineers 9 January~ 1983). It appears that the
gouge zone along the present tunnel alignment may be more extensive
than elsewhere owing to the wider zone of faulting. Limited exposure
in the vi nity of the tunnel alignment indicates that the zone of
shearing associated with the margins of the faults is also substan-
tially wlder thdn described elsewhere; strongly sheared argillite with
nodules, boudins, and di scontinuous layers of chert~ appears to extend
for about 400 feet on either side of the main fault trace.
The amount and sense of displacement along the Bradley River fault
zone is not well establi shed.. only marker horizon that can
observed on both sides of the zone is a da te dike which has ap r-
ently been offset about 1,000 feet in a right lateral sense. Slicken-
sides noted by D0l4l Engineers (January, 1983) and Woodward-Clyde
27
:::~::'
;:;;~;
K-0631-6J
{1979} r from o to 30° along the fault sugge i a ve rt i cal com~
ponent of up to 400 feet associ ated with the 1,000 of apparent
hori zontal di splacement.
The structure of the Bradley River fault zone-tunnel intersection is
further complicated by several rockmass discontinuities of unknown
origin, expressed at the surface as topographic lineaments, that trend
into the fault zone near or through the propos tunnel alignment.
Two of these lineaments trend northwesterly across the faUlt zone
without any apparent offset, and parallel a fault mapped about
1,000 to the north by Woodward-Clyde (1979) with a similar but
stronger topographic expression. If these lineaments are faults, the
amount of broken or crushed rock in the vicinity of their intersection
with the Bradley River fault zone will probably be greater than pre~
sentl y imated. Subsurface conditions as de ned by a boring in the
fault zone are outlined in section 6.30
5.4.2.4 Bradl River Fault to Bull Moose Fault Zone ~~~--~~~~~~~~~~~~~~~~~
Northwest of the Bradley River fault zone t tunnel alignment crosses
the highest elevations and best exposed bedrock ong its route. This
area is underlain predominantly by foli a illites with lesser
amounts of massive argillite. graywacke, and a single dacite dike~
Much of the foliated argillite contains nodules and thin discontinuous
layers of chert comprising about 10 to 20 percent of the volume of the
rock. A few massive lenses of very closely fractured chert up to
10 wide were also found interspersed with the foliated argillite
in this area. The foliation in the argillite and cherty argillite
stri from N-S to N200E and typically dips greater than about
75 de Exposures of massive argilli occur primarily within
about 1,000 feet of the Bull Moose fault zone and as isolated pockets
within the foliated argillite. There are two main occurrences of
graywa in this area. They are unusually exposed on hills
2036.3 and 2043.2~ the highest points along t alignment. These
graywacke masses are each about 300 fe thick. They are locally
28
K-0631-61
interspersed with foliated chertyargilli but in general are rela-
tively homogeneous and massive. The da te dike, although not exposed
on the alignment itself, appears to cross the proposed tunnel align-
ment along a N800E trend with a nearly vertical dipo
BedrocK outcrops along this segment of the tunnel alignment tend to be
widely to very widely jointed. However, discontinuities in the rock
mass are more significant than outcrops would sugge because the
larger fractures are commonly masked by soil cover and slope wash~
Hundreds of short, linear, soil-filled depressions can be seen in this
area, many-of which are presumably the surface expression of bedrock
joints and faults. Unfortunately, however, without r rock expo-
sure it is not possible to distinguish which of these features are
faults or joints.
La r lineaments, also common in this area~ present the same problem
for attempts to define their structural significance. A series of
lineaments located of and subparallel to the Bull Moose fault
zone are likely to be the surface ex sian of smaller faults asso~
ciated with the main fault trace, but exposures are insufficient to
conclusively determine their origin. Similarly, several weaker
northwest-trending lineaments recogni from air photos cross the
alignment southwest of lake 154203$ But in spite of relatively good
rock exposure in this area, we were unable to determine conclusively
whether these represent minor faults or prominent joint sets. In
either case exposures limit the width of these apparent discontinui-
ties at the surface to less than about 10 to 15 feet where they cross
t tunnel alignmento
5.4$2.5 Bull Moose Fault Zone
The main trace of the Bull Moose fault zone is located approximately
9,8UO feet northwest of the tunnel intake. It is expressed as a
narrow, topographic notch with a 200-foot-high. steep west wall. This
29
K-063J-61
area is densely vegetated and rock is expos in small isolated out-
crops. No exposures of gouge or broken rock were found in the fault
zone. but relatively undeformed rock on either side of the main fault
trace indicates that this zone must locally be less than about 50 feet
thick. As discussed above. a series of lineaments subparallel to the
main fault trace may represent fractures associated with the Bull
l'1oose fault. If SO$ shearing along the fault may have affected the
bedrock in discrete zones across an area over l~OOO feet wide. SUb-
surface conditions defined by a boring are outlined in 5e ion 6.4.
5.4.2.6 Bull Moose Fault Zone to Powerhouse Site
The bedrock exposure is much more limited ong this segment of the
tunnel alignment than it is to the southeast. This is particularly
true to the northwest of the surge tank 1ocation where forest and soil
cover mantle all but a few small isolated rock outcrops. The avail ~
able exposures along this section of the tunnel alignment indicate
that it is underlain predominantly by foliated and massive argillite~
Cherty argillite (greater than 10 percent chert nodules and layers)
and graywacke crop out in relatively small amounts, although boring
data (U.S. Army Corps of Eng; neers, 1982) i ndi cate that these rock
types are more common than their surface exposure suggests~ A creeks
which roughly parallels the tunnel alignment about 450 feet to the
southwest, provides the best bedrock exposures in the lowermost
1,000 feet of this section of the alignment. Bedrock is exposed along
this creek essentially from the bay to the vicinity of ~oring OH 13EX.
It cons i sts predomi nantly of argil i i te wi th 1 oca 1 cherty zones and
about 10 to 15 percent fine-grained graywacke.
The recognizable structural trends along this section of the alignment
in t s area conform to those elsewhere along the tunnel alignment.
Foliation in the argillites is consistently 0 ented at N-S to N20oE.
JOintlng is widely to very widely spaced in most exposures. with a
dominant strike of N75-85 c E, and dip of 80 to 85° North. neaments
30
K-0631-61
are weakly expressed or absent owing to the dense forest cover and
lack of rock exposure.
5.4.3 Powerhouse
The proposed powerhouse location is situated on a topographic bench
above the Kachemak Bay tidal marsh. This bench is underlain by rock
at shallow depth as witnessed by exposures along the shoreline bluffs.
However, with the exception of the bluff exposures and outcrops along
a stream about 450 feet to the souths the bedrock is almost completely
covered by a veneer of soil. Based on these exposures and previous
borings drilled to the south along the stream channel, the powerhouse
site appears to be underlain by highly fractured argillite and lesser
amounts of highly fractu graywacke~ A daci te dike a1 so occurs in
the area based on a single exposure observed near the exit port
Near-surface conditions were investigated with a test pit, as dis-
cussed in section 6$6~
The rock along the bluffs, comprised primarily of argillites contains
numerous minor shear zones, slickensided fractures, and tight to open
joints in various orientations& Further south along the creek, how-
ever, the rock is less fractured and joints are generally tight
very tight~
31
K-0631-61
6. SUBSURFACE CONDITIONS
6.1 General
The rocks of the McHugh Complex encountered during Shannon & Wilson's
subsurface exploration program at Bradley Lake have been classifi by
the same lithologic descriptions such as graywacke and argillite that
were used in the reconnaissance geologic mapping of surface exposures
(see section 5.3.2) and by previous investigators. The decision to use
these classifications was made for consistency and to facilitate the
evaluation of the engineering properties of the rocks.
In a geologic sense, the rocks in the Bradley Lake area are catacla ic
rocks, or rocks which have been broken and granulated due to stress and
movement during faulting, and which have regained primary cohesion
through metamorphic processes to same extent. According to the
classification system of Higgins~* the rocks in the Bradl Lake area
would be classified as a protomylonite. The origin of the rocks
explains their sheared textt1re~ intimate intermixing, and the often
extremely gradational contacts from one lithology to another,
Of the previous investigators the site, DOWL Engineers (January 1983)
acknowledged the existence of cataclastic rocks i.n association with the
Bradley River and Bull Moose Faults. In our opinion, whole of the
project area is most likely of cataclastic origin. Where appropriate in
the logging of the three Shannon & Wilson rock core borings, catacla ic
terminology has been used to describe textural features in the rock. A
glossary of selected terms from Higgins is included in this report as
Appendix B.
The rocks in the Bradley Lake area have all been metamorphosed to some
extent. But because it is difficult to assess the degree of
metamorphism in hand specimen, and for simplicity, the prefix li me ta-ll
* Higgins, Michael W. IICataclastic Rocks,fi U.S. Geological Survey
Professional Paper 687.
K-0631-61
has not been applied to the lithologic classifications. The major
lithologies encountered in the Shannon & Wilson exploratory borings are
discussed in the following paragraphs.
Graywacke was commonly encountered ,in the three borings along the
proposed tunnel alignment. This hard, light gray to gray material is
generally fine-grained to very fine-g ned. Its catacla ic texture
with local fluxion structure corrmonly contains sand and gravel-sized
clasts of argillite as well as stringers and wavy bands of argillite, as
illustrated in Photo 1. Calcite veins are also common., Joint spacing
in the graywacke is dependent on the occurrence of argillite within it,
as it is generally closely jointed where argillite is common~ but ranges
to moderately close to widely jointed where the occurrence of argil1ite
is not Significant.
Argillite was encountered throughout the borings in many different types
of occurrence. This dark gray to black material is generally foliated
due to shear stress (see Photo 2), but was encountered with massive
texture in small zones usually associated with zones of massive
graywacke. Elongated porphyroclasts of graywacke and chert are common
in the foliated argillite, and fluxion structure is common. Argillite
also commonly occurs as stringers and wavy bands with'in zones of gray-
wacke or chert.
Apparently the relatively lower strength of the argillite is responsible
for its susceptibility to mechanical deformation, evidenced by its
common shear-generated foliation and, more distinctly~ its occurrence as
fault breccia or gouge in the shear zones encountered (see Photo 3).
The ringers of argill ite within other more competent material s are
generally slickensided when broken, and most joint faces in ali of the
rock types encountered were coated with slickensided argillites and
commonly contained crushed argillite fragments.
Where a significant amount of chert occurs in the argillite as
porphyroc 1 as ts or 1 enses (over 10 percent chert), the resultant rock
type is classified as cherty argillite, as shown in Photo 4. The very
33
K-0631 1
rd porphyrocl asts of chert in a moderately hard fol iated arg; 11 ite
matrix range from sand to cobble~sized randomly throughout the rocks and
local sma11 zones can contain up to 70 percent chert. Porphyroc1as of
graywacke are also found in the cherty argillite. This rock is
generally closely to very closely jointed.
Very hard chert occurs in local zones up to 17 feet (12 feet
horizontally) thick within the depth drilled at the Bradley River and
Bull Moose faul t zones . Although usua lly interspersed with stri ngers
and local small zones of foliated argillite as illustrated in Photo 5 s
occasionally small zones of relatively iipure il chert were encountered.
Joint spacing in this light gray rock ranges from very close to
mOderately close depending on the occurrence of argillite within it.
Tectonically mixed graywacke and argill ite as shown in Photo 6 was
commonly encountered in the borings. The cataclastic texture and common
uxion structure of this material is composed of porphyroclasts and
interlayered wavy bands of the two lithologies. The graywacke retains
its massive texture in this material and the argillite can be massive to
foliated. Joint spacing varies from close to locally very close.
6.2 Intake Structure
Boring SW 83-1 was drilled in the vicinity of the proposed intake
structure near the natural outlet of Bradley Lake. Oriented in a S5°E
direction~ the boring was drilled to a depth of 155.3 feet at an inclin-
ation of 45°. The boring location is shown in Photo 7.
About 28 feet (20 feet vertical) of overburden sands, gravels, cobbles~
and boulders, including a lO-foot thick boulder, were penetra before
bedrock was encountered. Below the overburden, a 1 ternati ng zones of
graywacke and tectoni ca lly mi xed argil1; te and graywacke were encoun-
tered throughout the boring. The contacts between the observed zones
are usually gradational.
34
K-0631 1
Boring SW 83-1 was oriented to cross a north to northeast trend;
lineament observed at the site. Although no distinct shear zone or
thick gou was encountered in the boring~ the closely jointed argillite
lithologies are locally very closely jointed, and slickensided argillite
and fragmented, crushed argillite are common in joint apertures.
Two borings completed by the Corps of Engineers in this area, OH-16 and
DH-35, were drilled about 190 feet north-northeasterly of SW 83-1 on the
left abutment of the proposed dam. Substantial zones of argillite were
logged in these vertical borings, in contrast to the lesser amounts of
argillite encountered in boring SW 83-1.
6.3 Bradley River Fault
The Bradley River fault zone was explored by boring SW 83 ~ which was
drilled perpendicular to the fault trace at an orientation of N75°W and
at an angle of 45°, Drilled to a depth of 262.3 feet, the boring
penetrated two significant shear zones, the west and possibly east
branches of the fault. The general location of this boring is shown in
Photo 8.
From the surfa.ce to a drilled depth of about 30 feet, loose gravelly
sands with cobbles and boulders were encountered above bedrock.
Striations observed on a cobble from one of the two lengthy runs through
the overburden material suggested that these materials are, at least in
part, glacial.
Beginning at the. top of bedrock, shear foliated cherty argillite was
encountered, and encompassing the two shear lones, continued to a
drilled depth of about 197 feet. Chert porphyroclasts typically con i-
tute about 20 percent of this rock, however this occurrence varies
randomly throughout the material explored, and locally can be as much as
70 percent of the rockmass. This rock is closely jointed to locally
very closely jointed.
35
K-0631-61
Below a depth of 197 feet~ alternating zones of graywacke and chert were
encountered, with local zones of cherty argillite and foliated
argillite. Joint spacings in these materials increase to moderately
widely spaced joints when argillite materials are not significantly
present,
The two shear zones were encountered at drilled depths of 47.4 feet to
62.0 feet, and 138.0 feet to 175.6 feet (lO.4 and 26.9-foot horizontal
widths, respectively). The deeper shear zone correlates well with the
observed side hill trace of the we branch of the fau1t~ assuming a
near-vertical fault plane, The trace of the east branch of the fault is
not well defined topographically, but the. higher shear zone in the
boring COincidentally correlates well with the mapped trace of the fault
shown on Sheet 1 of Figure" 2. However, it is possible that additional
shear zones exist to the east of the upper one encountered in the
boring. The material observed from these zones is predominantly
brecciated argillite rock containing clasts of chert. Locally the rock
has been reduced to fault gouge consisting of breccia fragments in a
clayey silt matrix.
The cherty argi 11 i te adjacent to the shear zones is generally very
closely jointed and the argillite faces of the apertures are extremely
slickensided, often containing crushed rock fragments as .breccia and
gouge.
The Corps of Engineers' boring DH-10EX was drilled in an easterly
di rection at an incl i nation of 31 0 approximately 1600 feet north of
boring SW 83-2, on their tunnel alignment~ north of the suggested
convergence of the east and west branches of the Bradley River Fault.
Significant core loss at specific locations in their bOl~ing suggests
several shear zones that were penetrated at different depths. The lack
of core recovery fro~ these zones precludes specific information about
the materials that were penetrated, and it can only be surmised that
they were of a soft nature.
36
The Corps of Engineers' summary boring log for boring DH-IOEX describes
the materials encountered as thinly bedded argillite, and no mention is
made of secondary constituents. Exam; ion of photographs of the core
obtained from DH-IOEX shows significant amounts of what appears to be
chert as porphyroclasts, including local zones of concentrated chert
clasts, suggesting that subsurface conditions at that location may be
similar to those encountered at the location Shannon & Hilson's
boring.
604 Bull Moose lt
The tunnel alignment. crossing of the Bull Moose Fault was explored with
boring SW 83-4 (see Photo 9). Drilled at an orientation of N800W at an
inclination of 45°, this boring was drilled to a depth of 206.2 fee'to
Bedrock was encountered after only 4.2 feet of penetration, and the
shear zone of the Bull Moose Fault was encountered at a drilled depth of
about 146 feet.
A broad rum of occurrences for the typical lithological rock types
encountered in the Bradley Lake area was observed in the core from
boring SW 83-4. Random alternating zones of graywacke, argillite, and
chert, as well as mixtures of these litho10gies were logged within the
depth expiored.
From the top of bedrock to a drilled depth of about 50 feet, zones of
graywacke, argillite, and mixed graywacke and a illite were encoun-
tered. These closely to very closely jointed zones contain porphyro-
clasts of chert, and, be10w about 30 feet, local chert layers.
Significant amounts of chert were commonly encountered below a depth of
about 50 feet both as cherty argi 11 i te and zones of chert. These
closely jointed rocks occur with zones of very close1y to closely
jointed argillite and graywacke to the bottom of the boring at 20602
feet.
37
K-0631-61
Porphyroclasts of apparent altered dacite were encountered within cherty
argillite from a depth of about 170 feet to 189 feet.
The shear zone of the Bull Moose Fault was encountered from a depth of
about 146 feet to 154 feet in the boring (horizontal width of 6 feet).
The brecciated argillite and graywacke in this zone is locally sheared
to s 11 ty sand and zones of cl ayey gouge. The rocks adjacent to the
shear zone~ argillite above and chert below~ are highly fractured from
considerable shear deformation.
The vertically projected location of the shear zone encountered in
boring SW 83-4 is ~onsistent with the mapped location of the fault trace
on Sheet 3 of Figure 2 for a near-verticBi fault plane.
The Corps of Engineers! boring DH-17EX, drilled across the fault at a
location about 480 feet northeast of boring SW 83 ,inferred a 13~foot
wide fault zone in a zone of total core loss from 210.7 feet to 229.2
feet. This location is also consistent with a near-vertical fault
plane. Continued core loss below that zone in the Corps! boring sug-
gests the possibility of highly sheared rock adjacent to the main fault
plane.
The rock in the Corpsl boring is classified as a thin-bedded argillite,
with some cherty zones. Photographs of the core appear to show larger
concentrations of chert~ suggesting that at least some of the rock could
be classified as a cherty argillite, as fo'und in the Shannon & Wilson
boring.
6.5 Barge Basin
Boring SW 83-3 was located about 700 feet northeast of Sheep Point in
the mud flats on the east side of Kachemak Bay, in the area of the
proposed barge basin (see Photo. 10). A detailed description of the
materials encountered can be found on the boring log for SW 83-3~ Figure
5.
38
K-0631-61
From the surface to a depth of about 18 feet, clayey silt was
encountered, containing scattered stringers and thin lenses of fine
sandy silt~ pockets and lenses of silty clay~ and occasional small zones
of clean sand. Below about 18 feet, interbedded sands and silts with
random gradational changes were encountered to a depth of about 23 feet.
From 23 feet to 29 feet, clayey, silty~ gravelly sand with zones of
clayey silt was encountered. Below 29 feet s1ightly clayey, silty sand
with local gravelly zones was encountered to the bottom of the boring at
51. 5 feet.
Another boring, SW 83-3A, was drilled about three feet to the north of
boring SW 83-3 in order to obtain additional undisturbed Shelby Tube
samples from shallow depths at this location. From the surface to a
depth of 14 feet, slightly clayey to clayey silt with pockets and layers
of clay~ and small zones of clean to silty sand was encountered. From
14 feet to 16 feet~ the bottom of the boring, clean fine to coarse sand
with fine gravel was encountered.
The laboratory test results are summarized on Table 3, Summary of
Laboratory Test Results. Grain size gradations are plotted on Figures 9
through 11, compression test results are plotted on Figures 12 through
15, and Atterberg li'mit values are plotted on the Plasticity Chart,
Figure 16.
The sensitivity of the fine-grained soils was calculated from the
results of natural and remolded field vane shear tests, laboratory
Torvane tests, and unconsolidated-undrained triaxial compression ts.
Strength and sensitivity data from these tests are summarized on Figure
17.
The two pairs of field vane shear tests yielded the highest sensitivity
ratios, 8.6 and 5.2. Ten pairs of laboratory Torvane tests yielded a
relatively consistent average sensitivity ratio of 3.0. The three pairs
of triaxial compression tests yielded an average sensitivity ratio of
2.3. A pair of unconfined compression tests yielded a sensitivity ratio
of 1.2, this value is suspect because the wa content of the
39
K-0631-61
remolded sample was 3% lower than the natural water content of 24%, and
because the undisturbed sample exhibited a relatively abrupt failure.
The three undisturbed triaxial test samples all continued to deform
until termination of the test at 20% strain (see Figures 13 through 15).
Low undisturbed strength values obtained on the sample of silty,
gravelly sand from a depth of 23 feet may reflect either disturbance of
the material during sampling~ weakness of the material due to
interbedding, or the fact that only cohesive strength is being measured
on a sandy sample.
In order to evaluate possible errors cau by horizontal structure in
the soils when running laboratory Torvane tests paral1 to the axis of
the sample, a pair of tests was also run perpendicular to the sample
axis on a sample from a depth of 26.6 feet. Good reement was found in
the rength and sensitivity values from all four tests.
The cleanest fine-sandy interbed noted in our boring was found in a
sample from a depth of 26 feet. A mechanical analysis performed on this
sample (see Figure II) showed it to be a silty~ fine to medium sand with
medium and coarse sand-sized shell fragments. Cleaner sands were noted
in our exploration, but the sand contained a significant medium to
coarse fraction.
The results of Atterberg limit determinations on five samples are also
summarized on Figure and on Figure 16. The materiels tested are both
clays and silts of low to medium plasticity or compressibility.
Borings performed by the Corps of Engineers in the tidal flats of
Kachemak Bay describe the so11 5 north of Sheep Point as "fat ayll
becoming 1I1ean" with depth, and the materials south of Sheep Point as
"silty clayll, As laboratory testing was not reported on samples from
the Corps bor;ngs~ it is difficult to equate their classifications to
the material described in borings SW 83 and SW 83-3A, and suggestion
of trends based on the present limited information would be conjecture.
40
K-0631-61
In two borings performed by the Corps near the shoreline, one at the
Corps' tailrace location and one south of Sheep Point, artesian water
was noted above and near the soil/bedrock interface. Increased water
ow was noted with depth. This was not observed in our boring, however
the soi1/bedrock interface may not have been approached~ or our boring
may have been too far offshore to encounter such artesian water.
Although bedrock was not encountered in the Shannon & Wilson boring, it
should be noted that bedrock was observed in the banks of a drainage
channel about 100 feet north of Sheep Point.
6.6 He
A hand dug test pit was located in the area of the proposed powerhouse,
Shallow bedrock was confirmed at this site below about 1 to 2 feet of
overburden material (see Photo 11). A log of the test pit is shown on
Figure 8.
The dacite bedrock encountered in the test pit is similar to other
outcrops of dacite dike rocKs observed in the Bradley Lake project area.
Although the lateral extent of the material at the pm'lerhouse site is
not known. if it is a similar dike rC!ck, its width should not be
expected to be too great.
41
K-0631-61
7. SUt·1MARY AND CONCLUSIONS
7 .1 General
Shannon & Hilson's field explorations at Bradley Lake were primarily
designed to provide subsurface information at the proposed intake
structure. pOvlerhouse, and barge basin locations. to investigate the
thickness of the brecciated zones at the tunnel alignment crossir.gs of
the Bradley River and Bull Moose Faul ,and to provide an estima of
the percentage of various rock types expos along the tunnel alignment.
Subsurface conditions at the five sites which were explored are dis-
cussed above in secti on 6 The general character; sti cs of the rock
encountered are discussed below in section 7.2. Our estimate of the
distribution of rock types along the tunnel al ignment is presented in
section 7.3. Information on the tunneling characteristics of the rock,
based on test; ng by others and the resul ts of our subsurface exp 1 or-
ations s is summarized in section 7.4. Stability of the proposed berge
basin is discussed in section 7,5~
7.2 Rockmass Characteristics
The three borings cored in rock during this study were drilled in known
or suspected faul ts or shear zones, and the rock encountered in these
borings should not be considered representative of the project as a
whole, with respect either lithology or discontinuities.
LJithin this cOflstraint. rock encountered in the three explor?,tory
borings ranged from very closely to widely jointed, with joint sep-
arations, exclusive of gouge-filled fractures in fault zones, ranging
from tight to narrow (see Tab?e 2 for description of classification
systems), Rock quality, after the method of Deere~ was poor in all
three Shannon & Wilson borings. with the total RQD ranging from a low of
32% for boring SW 83-2 at the Bradley River Fault to a high of 510/, for
boring SW 83-4 at the Bull Moose Fault. The average rota1 RQD of the
42
three borings of 43% was significantly lower than an unweighted average
RQD of 60% calculated for 23 borings drilled by the Corps Engineers.
In our opinion, this reflects the nature of the fau~ or shear zones
penetrated by the three most recent borings. Unweighted average ROD for
the Corps of Engineers· borings ranged from a minimum of 29 to a maximum
of 93.
It is difficult to extrapolate the rock quality at a tunnel depth
significantly greater than the maximum depth of the borings drilled to
date. The greatest penetration of a Shannon & \'/11 son boring was 240
feet below the-ground surface at the Bradley River Fau1t. Maximum
penetration by the Corps of Engineers was 475 feet at the surge tank
location. Trends of slightly increasing RQD with depth can be seen in
at least the borings at the intake structure location and the Bradley
River Fault. However, such trends are difficult to assess when the
boring crosses a fault or shear zone. The penetration of boring SW 83-4
across the Bull Moose Fault was not great enough to reveal a reliable
trend of RQO with depth. Such interpretations may also be complicated
by the dependence of rock quality on lithology, given the variable
lithologies found in the borings.
Rocks of an major lithologic units identified in the surface geology
reconnaissance (section 5) were encountered in the three bor;ngs~ with
the exception of the dacite which was encountered only in the t pit
at the powerhouse locaticn. In the core, fracturE's and joints were
observed to be more widely spaced in the graywacke zones than in the
argillite. This fact is also supported by a study of the logs the
borings drilled by the Corps of Engineers. In their borinqs in which
graywacke predomina s the unwetghted average RQD avera 69%, while
in rings in which argilli predominated, the RQD aver?ged 48~L In
our borings~ joints or fractures in areas of mixed argillite and other
rock types (graywacke or chert) most often occurred in either major
zones or thin stringers of argillite. These surfaces were commonly
slickensided, at a variety of rake angles.
43
K-0631-61
Boring SW 83-1~ at the intake structure location~ was oriented
perpendicular to a lineament~ and approximatelY paral1e1 to t~e primary
structural trend of the project area. In this boring, joi ing at high
angles to the core axis was interpreted as pertaining to the lineament
(and/or the secondary joi set in the proj area). Numerous joints
at low angles to the axis of the core most likely reflect the primary
joi nt set. Bori ngs SW 83 and SW 83-4 ~ at the Brad1 ey River and Bull
Moose ults, respectively, were oriented rpendicular to the primary
structural trend. In two borings, joint angles near 45° to the
axis of the core predominated. While it is not possible to establ ish
the true orientation of joints in a boring inclined at 45° without
oriented coring, these joints most likely correspond to the predominant
vertical! northeast-southwest trending joint system typical of the
project area, especia11y since they are generally paral1 to the
lithologic grain of the core. Occasional joints sub-parall to the
core axis may correspond to the secondary east-west tr?nding joint set.
7.3 Rock Type Distribution
Based on reconnaissance geologic mapping, the footage and the percentage
of the various rock types along the tunnel alignment are as lows:
Li thol ogy
Massive Argillite
Foliated Argillite ( <10% Chert)
Foliated Cherty Argillite ( >10% Chert)
r~ixed Graywacke (50-65?~) and
Argillite (35~50%)
Graywacke
Dacite
Chert
Severely Brecciated Rock and Fault Gouge
44
5$400
3,660
3 s 740
3~550
1,600
100
50
18,150 feet
Percentage of
Tunnel
30
20
20
20
9
<1
100%
K-Of.31 1
This estimate is based on the observed and interpreted surficial
geology. The length of each lithologic unit was measured from the
geologic map with no attempt to correct for the angle of the tunnel.
The degree of accuracy of this estimate is limited by a lack of bedrock
exposure along much of the tunnel alignment, and by the possibility that
the surface geology may not accurB.tely represent rock conditions in a
deep tunnel along the same alignment.
The percentage of. chert tabulated above reflects only observed or
inferred thick layers of relatively massive chert. During the recon-
naissance mapping, this chert 9 as well as the II c herty argillite,tI
appeared be more common in the vicinity of faults or major shear
zones than elsewhere in the project area. During the mapping, rocks
mapped as cherty argil1i were observed with a maximum of only about 20
percent chert.
However, in the borings the Bradley River and Bull Moose Faults,
rocks logged as cherty argillite commonly contained as much as 50
percent chert as porphyrocla ~ lenses, or boudins, and in local zones
contained as much as 80 percent chert. It cannot be said whether this
high percentage of chert is confined to the major fault zones, where
surface exposures tend to be sparse~ or whether general lack of surface
exposure in the project area prevented the observation of the very
cherty argil1i during the reconnaissance mapping. The very cherty
argi1l He in the borings was not classified as IIchertll or incorporated
into the percenta of chert in the table above because the chert tends
to be separated by masses or lenses of argillite and thus is not the
massive, amorphous rock normally associated with the classification of
chert. In our opinion it does not seem that this cherty argillite would
be as hard as a pure massive chert. However~ whether the II rty
argillite!! will truly behave more like a chert or an argillite in terms
of tunneling characteristics should be the subject of further study.
The cherty argillite classification was not used by the Corps of
Engineers in the logging of their borings, aY'd references to chert in
_ 45_
K-0631-61
the logs are limited. Observation of a limited amount of the core from
these bod ngs shows a hi gh percentage of chert in the bar; ngs at the
Bradley River and Bull Moose Faults, borings DH-IO and DH-17, respec-
tively. This observation tends to support the assumption that major
amounts of chert are found near major fault zones.
With the exception of the width of zones of fault breccia and gouge,
subsurface information from Shannon & Wi1son!s borings was not used to
modify the estimates tabulated above because their total horizontally
projected length corresponds to only sl; 1y more than 2 percent of the
tunnel length. likewise. Corps of Engineer's borings were not
incorporated i because in our opinion their vertical orientation is not
necessarily representative of the distribution of lithologies given the
predominantly vertical structural grain in the area.
The percentage of fault breccia and gouge may be greater than indicated
above, because of the sparse subsurface information to date. Two major
structures, the Bradley River and Bull Moose fault zones, are
recognized. These faults may affect zones up to about l~OOO feet wide~
and appear to c;:onsi of multiple fault planes. Presently known in-
tensely crushed or gouge zones appear to be restricte-d to less than
about 40 feet \l'/ide in the Bradley River fault zones and less than 10
feet in the Bull Moose fault zone. but the percentage in the table above
excludes rock which ;s probably still more highly fractured than norma1
for the project area. Several other strong lineaments that trend across
the tunnel alignment are suggestive of faulting. One lineament that
crosses the al ignment between the intake and Bradley River fault zor:e
could contain a broken and crushed zone up to 200 feet wide, making it
potentially as significant as the larger known faul Determination of
the origin of this and other lineaments awaits further investigation
because soil cover obscures the bedrock along their traces.
As addi ona 1 subsurface data becomes ova 11 ab 1 e, the estimate of rock
type distribution given above should be modified as necessary~ to
reflect the additional information. Similarly~ once the final grade of
the tunnel has been estab1ished these numbers can also be refined.
46
1<-0631-61
7.4 Tunneling Characteristics
The 1 imited subsurface exploration program carried out by Shannon &.
Wilson at Bradley Lake was designed to investigate conditions relative
to tunneling only at the crossings of the Bradley River and Bull Moose
Faults. Tunneling characteristics along the remainder of the power
tunnel alignment are being evaluated by others. This work involves
correlating surface geologic mapping by Shannon & Wilson with test
results on rock core from borings drilled by the Corps of Engineers.
A major concern with the crossings of the Bradley River and Bull Moose
Faul was the possible presence of materials in the fault zone which
might "run" into a tunnel excavation. At the location explored, the
Bull r~oose Fault was found to contain a 6-foot wide shear zone of
arg; 11 ite and graywacke whi ch \.'Ie re 1 oca 11y crushed to gravel and sand
sized particles, within a matrix of silty clay. The western branch of
the Bradley River Fault was found to contain a 27~foot \l'Jide zone
crushed rock and slightly clayey, silty sand gouge.
Neither of these fault cro'ssings encountered gouge which appeared to
have the potential for running at the depths and locations explored.
The Corps of Engineers I borings at their proposed tunnel crossi of
the two faul encountered almost complete core loss in what was
interpreted as the fault zone, but the different drilling techniques
used by the Corps may account for this core loss. Drilling water loss
was not significant in either the Shannon & Wilson or Corp of Engireers'
borings at the two faults. The Corps of Engineers did rot pressure test
their boring at the Bradley River Fault, and what was interpreted as the
fault zone in the Bull Moose Fault did net take significant water during
pressure testing. Groundwater conditions were not tested in the Shannon
& Wilson borings, and in any case might be significantly different at
tunnel depth than at the depth explored.
Significant zones of lower than average rock quality (RQD) for the
project area were encountered in the vicinity of the two faults. Rock
quality within the Brad1ey River fault zone was poor to very poor {based
47
K-0631-61
on ROD after the method of Deere), whil e the rock to the If/est of the
fault zone increased in quality from poor to good or very good with
distance away from the fault. To the east of the Bull Moose Fault rock
quality was good to poor, and to the west was fair to very poor.
Tentative penetration rates for a tunnel boring machine at Bradley ke
have been assigned to variolls rock types encountered in the Corps of
Engineers I borings by Dr. Alfred Hendron based primarily on Total
Hardness calculated from laboratory tests on samples of the rock. The
results of these tests show reasonably distinct ranges of Total Hardness
for the three rock types tested~ argillite, graywacke, and chert. The
argil1i originally tested was foliated argillite, and a single 1ater
test showed that rock classified as massive argillite was similar to the
foliated argilli in Total Hardness~ but that its unconfined
compressive strength fen IJlJithin the range of strengths of samples
classified as graywacke.
The U.S. Army Corps of Engineers did not test the hardness of the rocks,
but did perform unconfined compression tests on rocks c1assified as
Uinterbedded graywacke and· slate!!, IIgraywackel!, and liquartz-graphitic
slate~. It is perhaps significant to note that the compressive strength
values determined by these tests are somewhat higher and more scattered
than those determined by Dr. Hendron. Whether this strength difference
corresponds to a simil ar difference in hardness should perhaps be a
topic of further study if it becomes necessary to refine penetration
rate estimates for a tunnel boring machine.
No tests were run on rock classifi as "cherty argill Hell. As
discussed in section 7.3, this rock type was a major constituent of our
bari ngs in the Bradley River and Bull Moose fault zones, and vias ob-
served to contain considerably more chert than was observed in surface
geologic mapping. The possible unique properties and distribution of
this rock type should be evaluated in further refinements of tunneling
rates.
48
K-0631-61
Of perhaps less concern are the prr.perties and distribl.Jtion of the
It vo lcanic graywacke" identified in thin section and discus in section
5.3.2. More needs to be learned both about its distribution and i
strength and hardness properties before its tunnel ing characteris cs
can be properly evaluated.
Another concern in evaluating the tunneling characteristics of the rock
types on the project is their cataclastic nature and sheared and
interlayered texture. Lenses and stringers of argillite commonly occur
within the harder graywacke and chert 9 and on a large scale may make
excavation easier than test results might indicate. Conversely~ such
variation in rock types makes it difficult to select rock samples for
ing in the laboratory and care must taken to arrive at
representative test results.
7.5 Barge Basin Sol1 Prc.Qerties
The potential stability of the soils in the vicinity of the proposed
barge basin was evaluated by a laboratory testing program on samples
from the single boring location in that area. These soils consist of
soft to stiff, si1ty clay and clayey silt overlying silty and clayey
sands.
The sensi vity of the fine"'grained so11s was calculated from the
results of natural and remo1ded field vane shear tests, laboratory
Torvane tests~ and unconsolidated-undrained triaxial compression tests.
Strength and sensitivity data fr~m these tests are summarized on Figure
17. The two pairs fi d vane shear tests yi e 1 ded the hi ghest
sensitivity ratios, 8.6 and 5.2. Ten pairs of laboratory Torvane tests
yielded a relatively consistent average sensitivity ratio of 3,0. The
three pairs of triaxial compression ts yielded an average sensitivity
ratio of 2.3.
Another concern with regards to the stabi 1 ity of the proposed ba rge
basin is the possible presence of interbeds of potentially liauifiab1e
clean sands in the s-ilts and clays. The cleanest fine sandy interbed
49
K-0631-61
noted in our boring was found in a sample from a depth of 26 feet. A
mechanical analysis performed on this sample (see Figure 11) showed it
to be a silty, fine to medium sand with medium and coarse sand-sized
shell fragments. Cleaner sands were noted in our exploration, but the
sand contained a significant medium to coarse fraction.
The results of Atterberg limit determinations on five samples are also
summarized on Figure 17 and on Figure 16, The materials tested are both
clays and silts of low to medium plasticity or compressibility.
These test results from soils in the vicinity of the proposed barge
basins while suitable for evaluation of feas'jbility, should not be used
for design purposes. In addition to possible variation of soil types
between locations in the tidal flat deposits~ not all representative
soil types may have been sampled or tested at this given location.
While the Corps of Engineers' General Design Memorandum No.2 does not
contain soil test resul ,significant differences can be seen bebleen
the field classification of materials from north of Sheep Point and to
the south of Sheep Point. The material to the north~ in the area to the
west of the Corps' proposed powerhouse location, is classified as Hfat
clayll ~ while the material south of Sheep Point is classi ed eS lisil ty
clai'. Unfortunately, these groups of holes were logged by different
geologists. Given the difficulty of field c1assifying borderline clays.
it is difficult to state whether such variability actua1ly exists in the
tidal ,flat deposits.
The soils from our boring in the barge basin area were found to have
pore water salinity of 3.0 and 1.4 parts per thousand in the two samples
tested. Given the dependence of sensitivity of at least some c1ays on
their salinity, consideration shou]d be given to possible leaching of
clays in the barge basin area as a result of the discharge of fresh
water from the tailrace of the powerhouse.
Artesian water flow was noted on the 10gs of two of the Corps of
Engineers' borings located just offshore in the tidal flats~ one north
50
K-0631-61
of Sheep Point, the other to the south. No artesian water was noted in
the Shannon & Wilson exploration at this site.
51
TABLE 1
SUNr~ARY OF SUBSURFACE EXPLORATIONS
-~ ---
Vertical
Inclination Footage Depth of
Boring location Orientation of Boring Ori lled Penetration Remarks ,. ~.
83-1 Intake Structure S E 45° 155.3 109.8 Rock coring
SW 83 Br'adley River Fault N 75°W 0 262.3 185.5 Rock corin9
SW 83-3 Sa Basin Vertical Verti cal 51,5 51.5 Rota ry IIlash;
Soil sampling
techniques
SH 83-3A 8arge Basin Vertical Vertical 16.0 16.0 Drill ed to
obtain
supplementary
samples for
83-3
S\'1-83-4 Bull Moose Fault N SOoW 0 206.3 145.9 Rock coring
Fresh
t~oderd te I y
weathered
Highly
'",eatilered
Residual
Very Hard
Hard
Medium
Soft
Very Soft
No visible sign of rock material weathedng; perhaps
slight discoloration on ~ajor discontinuity surfaces.
Discoloration indicates weathering of rack IlliIterial and
discontinuity surfaces.
tess than thirty five percent of the rock material 1s
and/or disintegrated to <l soil. fresh or
oured rock is present either as a continuous
framework or as corestones.
:More than thirty five
decomposed Indlor di
of the rock material is
to so i L Fresh or
di sco 1 ollred rock is
fr~mework or <'IS
either as a discontinuous
All rod material is decomposed andlor disintegr~ted to
soi. fhe original mass structure is still lafgely
intact.
All rod material is converted to soil. The
structure and Olaterial fabric are destroyed.
lar'ge change in volume, but the soil has not
Significantly transported.
Old ss soil
There is i!
been
Cannot be scratched with knife or sh~rp pid. 8reaking
of hand specimens requires several hard blows of a
geologists pick.
Can be scratched with knife or pick only with difficulty.
Haru blow of hammer required to detach hand specimen.
or gouged 1/16 in. deep firm pressure
or pid pOint. Cdn be in small chips
about 1 in. Illilximum size by har'd blows of the
a geologist's pick~
Cdn be or grooved readily with knife Or picic
point. be excavated in chips to pieces several
inches in size by moderate blows of a piCK point. Small
thin pieces can be broken by finger pn~sslJ'·e.
Can be Cd rvcd with kn fe. Cdn be excava ted re~d i 1 y with
of pick. Pieces an inch or more in thickness can
broken by finger pressure. Can be scratched readi ly
by fing!'r nail. <
For Engineering Descriptiun of Rock -not to be confused with Moh's
scale for minerals.
Table 2
of Rock Methcrls
Spacing
Very close
Close
less thdfl 2 10.
2 in to i ft.
ft. to 3 ft.
3 ft to 10 ft.
Hore than 10 ft.
Moderately dose
Wide
Very thin
Thin
Medium
Thick
Very wide '1e!"Y Thick
After Deere. 1963 d
NOH: Joint spacing ,·efers to the distance normal to the pl,]ne of the
joints of I stngle or ·set" of joints which Ire parallel
to each other or so.
TERM
wide
Moderately wide
Moderately narrow
Nanow
Very narrow
Tight
APERTURE
Over 200 mm
60-200 liln
20-60 II'iTl
6-10 Ilill
2-6 mm
Over 0 to nil I
lero
ROCK QUlIlITY !lESIGNATOR1RQIl)
ROO iI! % 100 X __ ._-___ o_f ... C'-o .. r_e in Pieces 4 in. and
BQ!J.
Exceeding 901,
90-75
75-50
50-25
les s than 25~
length of Run
Good
fair
Poor
Very Poor
After Deere. 1967"
NOTE: Diagnostic Description is intended primari
problems with tunnels or excavations in
for evaluating
IDeere. D,U. "Technical Description of Rock Cores for
Felsm~~chdnik dnd lllgeniergeologie.
, pr. 17-22.
bOeere. o.u. et al .• "Oesigll of Surface and NedI' Surface Construction
in Rock Proceedings, 8th Symposium on Rock Mechanics, The
American Institute of Met,ll1urglca·1 dnd Petroleum
Engineer, Inc., New York pp. 237-302
from: Society of Civil Enyineers. Journal of the Soil Mechanics and
foundtaions Division. Vol. 98, No. SM6, I'p. 568-569, June 1972.
:0
;.)
I v
TABLE 3
SUMMARY OF TEST RESULTS
BORING NO. SW 83-2
lit ~ r;;1j~~;a~~ 41 cr ~ J' ~ ~ ..., ~~ ~ "" ~ ~$ A ~~ l;!I.. I~j' Ii ~~ A~$ :i: i' $~f ,it' l' ~ #$ J' ~
", l4' <f '3:" ~ 1t-if: J',. ~ cf ,. .....:r ~ ~ ... a ~ d' (j Q.i (;I !".I ..,. 8 ~ /IJ.'"
R-31 158. ~' 8 Fig 9 18-13
---.
158.2
-------~~
---~~--
.~ ..
-
-r---'-----.
_. --
-_. ---
----
-_.
--~-~-~-------
...
..
-----... ~
r---~ .. -----._-.-,-~.---
------~-"-----
----_. --.~~-----.. ...
--"----'---~---,---~
-.---....
-.. ----.. -.-
JOB NO. K-0631 DAn Seet. 1983
CLASSifiCATION
Gray, clayey, silty fine to coarse ---
SAt-Tn (fault gouge with rOC'!k fragments)
.-------
------
---
--
___ ow
.--.--~
-""~ --------------
.. ~~---' -----~.
-----
._-
.. -----
-------.--...
---.-----~---
-.-,~~ .-~---~ ~-~~---
-~,~-
TABLE 3
SUMMARY OF TEST RESULTS SHANNON " WilSON
~1 83 3 K 0631 BORING 00. ---DAn sept 1983 J06 NO.
~ tffl;l;/f.ri ;{j~~ ~ O· ~ it ~ ~ '" .... (;)P ~ ~ ~ "i ~ .$ A, N <!'t.-; ~ I ~~ If ~~$ A,::J/ ~ it ~! S' ~,<I. q,~! s fff~ Ci.ASStilFiCAnON ~ ~ '1 ~ ~ ',3:T 0 ~ i:j ~ T ~ T':::':': o.r ~ ~ o " 10 G ~ " 1J~4.l. v
s-2 14 0 5-5 • 0 24 110 Fio 10 2.63 27-21 19.2 5 'IV=0.35 tsf DaI:'~ gJ:'~Y' clayey _SILT to si.lty CLAY, trace
pp=o 9-1 25 fine sand ----tsf --------
Salinity=3.l%% --
----
S-2 iRemold 21 109 16-.0 Same .. ~~
--------.-
S-2 5.0-5.5 24 106 18.1 Same --..
------..
S~2 IRemold 24 104 6.8 Same _.
-'-
___ ow ---------
S-2 6.2 27 Dark oray, clayey SILT with occ. len::.t::::. of _lty
fine SAND, occ . pockets of silty ClAY
----.~~ .. .. .. ---. . -~ .--
~ 12 0-22 107 13.4 Dark gra.YJ c:tEyey SII:r, trace oflin~ sand
12.5 26
--
S··4 Remold 23 103 24-21 5.2 Same ---..
8-4 13.0 29 Dark gray, slightly silty fine SAt\1D with occ. -
h :>l;: of sandy cl ayey SILT ---'
--_._-.-_. --
S-7 22.9-21 103 Fi9...1Q .. 24~t'JP 5.1 Dark gray f §1,t9111:::tyglayeXl ~iltY1 fine to ... ----
23.6 -----.. ~ucu.qc. 2~ , fine to coarse S.AND
.. --_ . -----
8-7 Remold 24 3.5 Same .. -.. '-~-----------_ .. ,--1--.---' ---,-, -.'--
-"'-----~ i------. ---
TABLE 3
SUMMARY OF TEST RESULTS SHANNON & WILSON
BORING NO. ~sw 8_~:3 JO~ NO. K-0631 DAilE Sept 1983 _ ...
I/J tfiwl);/h~~~~ J! 0' ~ " ~ ~ '" iJP ~ ~ ~ ~ ~ ~ ~ A. ~ f! "' .... ~ ~$ ,! ~$ ~ ~T bJ:t§ '~4,~ l 1:$ I' ~ CLASSlflCATSOINI $ 4( Q~.$? ,. ~'iJ" '" ~ o-t ~ ~!!. It ~ i ~~~ y
S-9 26.0 17 IFig 11 Dark qray, slightly silty, clayey fine to coarse --
SAl\!1)1 with trace of fine gravel. and
1-------
fraoments throuqhout
---.--
clayey SIL'r~::::~race of sand 8-9 26.7 34 l~alinity=1.4% Dark gray, ---
'I'v=0.43 tsf -
~---~~-------
0.12 tsf Rem. -Para11 .:>1 to ~tlinq ------
Tv=O.41 tsf -" ---------
0.14 tsf __ Rem. --------
Tv=O.34 tsf ------... _----_. ~ ------._-
0.12 tsf Rem. "'" I-r'I=.L 1 ; ""11 1 ;:10 r to 'h.:>iln ing --
f-------Tv=O.40 tsf -----"' ...... -------..
0.12 ti?f Rem. -
35.5"::-Fig 11 -
Dark gray, slightly claY~YI silty fine to coarse S-16 16
37.5 SM1) with ctL't of fine arnvel
-----I------~
--.. ~
-------~-.
--------------
--"-~---
--~ .. --I-.... ------_ .. .. -
"------.. --
.. _---------. --------_.
-.-~~ -",-,-.~~-'¥'-... -
------
.----------------
TABLE 3
SUMMARY OF TEST RESULTS SHANNON & W~lSON
BORING NO. SW 83--311. Joe NO. K-0631 DATE Sent 198
1//!1;;Z~~ it! lit $ .p ~ &0.1 ... ~ ~ ~ ~ "" f ~$t.~ $~ $ .... ~ ~~ !t# ~h. ~ ~ ~s 4:1 Ib' J:! CI.ASSIFaCAnON ,;r~ <ll~ "" ~"'v ~, <! ~ &0.1 ~ ~ ~ T j~ T;I.::: -t~"'!if ~ i:}
J' (lI ~ U .... 0 " ta'" 0
v " -
~-1 i1 f1-1. R 2q 12-71 'I'V=0.39 tsf Dark arav. clayey sn.'T' with J;,"-},,; lavE'~~ of ..
_ .. -.. 0.11 ts~ Rem. silty CIAY .-
--.. __ 'w --
8-1 3.0-3.1 35 Tv=O.27 tSf Same --
10.10 tsf Rem . . -
---~-.
s-2 8.1 .. Tv=O.56 tsf Gray, sljShtl v clayey Sua' locally with trace
0.18 tsf REm. fine sand. occ. rY'Ir'kpi-q or lavers to ls thick of
gray sIt :y CLAY
.. -.~
---
S .. -2 8.5 24 25-17 Tv=O.62 tsf Same ..
_. ----~-0.20 tsf Rem ----------------
--.. -
LB. 9.5 24 Tv=0.62 tsf Same
0.46 tsf Rem. .. -.. --._-----
.---------~.. -.-----.-.. ~-
8-3 14.6 17 Dark qrav to black, clean fine to coarse SAND, !---_. ---
trace of subqranular fine arqillite qravel
--.-~-~-'''~
--.• -.. ---
--,. -------'. --_.--_._--
---_. ----,,--. .. ----
----1---._--_. -_. . _-.
_._--------------.. _-------~-~-~~
.. _------. ---=---~~'.~~-~-
__ ~v~_~.~ ___ .·_
-----'---_.-~----,,-~"'--
--~--
-...
I
[
l:
[ .
I
i
l
l.
[
r .
[1
/
, ,
KACHEMAK BAY
) // :~
: '
/I . , ,
\
.,-
I
"
POWER 'r
HOUSE ,_ \.:,.
U V'TP.' ,
PROPOSED/'
BARG E BASIN-
,/
\
\
\
\
\
\
/
I (
GEOLOGIC MA~
FIGURE 2
SHEET 4 OF 4 ) ,
I
/ (
/
/
\
/
~,
(
~" ... \
t SU.JIGE " \ \\ i
. TANK. GEOLOGIC MAP _ ~ . /
( -......-.~FIGURE 2 ~ SW83-4 "0
\ SHEET 30F 4 f/
. \ I
-) ;( ( l\
v
, ( \
\ ,or:? ~
/ )
. (D
I
\\
\
\ ' . ,
\ .
\
\
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o
I
500 1000
I I
2000
I
SCALE IN FEET
3000
I
4000
I
. ,
--.
~ ......
GEOLOGIC MAP
o """FIGUBE 2)
i OO SHEET :2 OF 4
~
SW83·2
l~) 0
c
.' o
j
GEOLOGIC MAP
FIGURE 2
SHEET 1 OF 4
6
,
INl'A KE l...,
STR UCTUR E ~_; \ '--,
, SW~3-1
j \
BRADLEY
LAKE
o
EXPLANATION
,I BOUNDARY OF GEOLOGIC
MAP AREA ,
~ SHANNON & WILSON BORING
SW83-4 LOCATION AND NUMBER
. i ~ TEST PIT LOCATION AND
TP-l NUMBER
STONE a. WEBSTER ENGINEERING CORPORATION
BRADLEY LAKE HYDROELECTRIC POWER PROJECT
GEOTECHNICAL STUDIES
LOCATION MAP
SEPTEMBER 1983
SHANNON a. WILSON, INC.
Geot.ehnlC81 Con.ultants ,
K.()831·81
FIG. 1
,
M
o 17" __ ' ,"".,
f-
, , i
'/ ,
j
I
NOTES:
1) See Figure for tocation of geologiC
map_
2) Topographic base from U.S. Army
Corps of Engmeers. Contour interval
is 5 feet.
, f /
o
I
100
I
200
I
400
I
SCALE IN FEET
600
I
,
\
800
d
,
\
BRADLEY
LAKE
Qa
Kg
Ka !l
Q.
E Kafrn~
::l
J:
ITriT,i1I " KaC~:O
Ka9rn
Kd
, . , , , ' . . , . . . . . ' . . ,
50 --.....:.-,
;tI85
~o
---€1
DH-17EX
EXPLANATION
QUATERNARY OEPOSITS 1 undifferentiated; Includes glacial
outwash, till, and colluvium. Shown only in vicinity of Intake.
GRAYWACKE; massive, weakly metamorphosed sandstone with
minor argillite layers.
MASSIVE ARGILLITE; weakly metamorphosed siltstone and
very fine sandstone.
FOLIATED ARGILLITE; Pervasively sheared, weakly metamor-
phosed siltstone and very fine sandstone with less than 10%
nodules, boudins, and discontinuous layers of chert.
FOLIATED CHERTY ARGILLITE; as above with 10·20% nodules.
boudins. and discontinuous layert of chert. Includes it few layers
of fractured, massive chert to 10 ft. thick.
GRAYWACKE & ARGILLITE, undifferentiated; complexly mixed
assemblage consisting of 50·65% graywacke and 35-50% argillite.
Argillite is predominantly foliated with less than 10% chert.
DACITE DIKE; weakly metamorphosed, fine grained, porphyritic
intrusive rock.
Rock not exposed within about 200 feet of tunnel alignment.
LitholnQY inferred from more distant exposures, topographic ex-
pression, andlor adjoining rock across structural trend.
Rock exposed within tunnel alignment corridor or within about
200 feet of tunnel alignment..
FAUL T; approximately located, showing rake of slickensides
LINEAMENT; approximately located
LITHOLOGIC CONTACT; approximately located
STRIKE & DIP OF FOLIATION
STR IKE & DIP OF JOINTS
Shannon & Wilson
80 RING LOCATIO N; arrow shows orientation and horizontal
projection of inclined boring
U.S. Army Corps of Engineers
BORING LOCATION {all borings at dam site not shown}
STONE & WEBSTER ENGINEERING CORPORATION
BRADLEY LAKE HYDROELECTRIC POWER PROJECt
RECONNAISSANCE BEDROCK GEOLOGIC MAP
OF THE INTAKE. TUNNEL ALIGNMENT.
AND POWERHOUSE SITES
SEPTEMBER 1983
SHANNON & WILSON, INC;
Geot.dlnical ConlUltalnts FIG. 2
SHEET 1 OF 4
, ,
,
/
t· /....-. ' i / /
I, /, 'j
~/
/
NOTES:
1) See Figure 1 tor location of geologic
map.
21 Topographic bale from U.S. Army
Corps of Envineers. Contour interval
Is 6 feet.
i
/
/
a 100 200 , I ,
"'~)
'i ',1'1"'-' (
j \ I ,-,,",
\ '-.J
400 800 800
I I
SCALE IN FEET
. ' '~"," ;; -.
, ~ ,,',.-.. . ! 0-
W w
:t ..
o
0-
w Vl'l~al!J ,,",,",\'1" z
~£~~~'~'Jll!~l~'~'\I~
<
:Ii
• 0 (lo 0
() I';)c '" '" · "" .' :. (j .. t)
Qa
Kg
Ka
KagW
Kd
. . . , , . . , . · . , · . ,
50 --~-
~85
~O
-$
DH-t7EX
EXPLANATION
QUATERNARY DEPOSITS, undifferentiated; Includes glacial
outwash, till, and colluvium. Shown only in vicinity of Intake.
GRAYWACKE; massive, weakly metamorphosed ""dstone with
minor argillite layen.
MASSIVE ARGILLITE; weakly metamorphosed siltstone and
nry fine sandstone.
FOLIATED ARGILLITE; Pervasively sheared, weakly metamor-
phosed siltstone and wary fine sand stone with less than 10%
nodules, boudinl, and discontinuous layers of chert.
FOLIATED CHERTY ARGILLITE; .. above with 10-20% nodule.,
boudinl, and discOn1inlAoui layers of chert. Includes 8 few layen
of fractured, massive chert to 10 ft. thick.
GRAYWACKE & ARGILLlTE 1 undifferentiated; complexly mixed
assemblage consisting of 50-65% iraywacke and 35·50% argillite.
Argillite is predominantly foliated with less than 10% chert.
DACITE DIKE; weakly metamorphosed, fine grained. porphyritic
intrusive rock.
Rock not exposed within about 200 feet of tunnel alignment.
Lithology inferred trom more distant exposures, topographic ex-
pression, andlor adjoining rock across structural trend.
Rock exposed within tunnel alignment corridor or within about
200 feet of tunnel alignment.
FAUL T; approximately IOelted, showing rake of slickensides
LINEAMENT; approximately located
LITHOLOGIC CONTACT; approximately located
STRIKE & DIP OF FOLIATION
STRIKE & DIP OF JOINTS
Shannon & W Ihon
BOR ING LOeA TlON; arrow shows orientation and horiz-ontal
projection of inclined boring
U.S. Army Corps of Engineers
BORING LOCATION
STONE &: WEBSTER ENG
BRADLEY LAKE HYDR
RECONNAISSANCE BEDROCK GEOLOGIC MAP
OF THE INTAKE. TUNNEL ALIGNMENT.
AND POWERHOUSE SITES
SEPTEMBER 1983
SHANNON 81 WILSON, INC~
aeotechnle.1 ConsulUlnlt
K.(I63'..e,
FIG.2
\ ,
\
-"
r
{
1
Kac
~IDt+ll
'-,
."
NOTES:
,
\ ,
\ ,
'.
, ,
1) See Figure 1 for location of geologic:
map.
2) Topographic base from U,S. Army
Corps of Engineers, Contour interval
jt 5 feet.
\
\
.. ~-
'C'\ ..
! .--, ' c
/
I
j
\
(
"
o 100
I
200
I
400
I
SCALE IN FEET
600 800
\
/ ,
" . ' ~
______ ~L_~ __ ~~~ ____ _L __ ~~~~~~ __ _,
N
>-w
w
:::
'" o >-
w
Z ...
:t
" >-.. ::;;
Qa
Kg
Ka
Kat
KagD
Kd
50 --...,.,:--
;tIS5
Xo
---B1
DH·'7EX
EXPLANA TlON
QUATERNARY DEPOSITS, undifferentiated; Includes glacial
outwash, till, and colluvium. Shown only in vicinity of Intake.
G RA YWAC KE; massive, weakly metamorphosed sandstone with
minor argillite layers.
MASSIVE ARGILLITE; weakly metamorphosed siftstone and
very fine sandstone.
FOLIATED ARGILLITE; Pervasively sheared, weakly metamor-
phosed siltstone and very fine sandstone with less than 10%
nodules, boudins, and discontinuous layers of chert.
FOLIATED CHERTY AAGlLLlTE; as above with 10~20% nodules,
boudins, and discontinuous layers of chert. Includes a few layers
of fractured, massive chert to 10 ft. thick.
GRAYWACKE & ARGILLITE, undifferentiated; complexly mixed
assemblage consisting of 50~65% graywacke and 35·50% argillite.
Argillite is predominantly foliated with less than 10% chert.
DACITE DIKE; weakly metamorphosed, fine grained, porphyritic
intrusive rock.
Rock not exposed within about 200 feet of tunnel alignment.
Lithology inferred from more distant exposures, topographic ex-
pression, and/or adjoining rock across structural trend.
Rock exposed within tunnel alignment corridor or within about
200 feet of tunnel alignment..
FAULT; approximately located, showing rake of slickensides
LINEAMENT; approximately located
LITHOLOGIC CONTACT; approximately located
STRIKE & DIP OF FOLIATION
STR IKE & DIP OF JOINTS
S hannan & Wilson
BOR ING LOCATION; arrow shows orientation and horizontal
projection of inclined boring
U.S. Army Corps of Engineers
BOR ING lOCATION
STONE & WEBSTER ENGINEERING CORPORATION
BRADLEY LAKE HYDROELECTRIC POWER PROJECT
RECONNAISSANCE BEDROCK GEOLOGIC MAP
OF THE INTAKE, TUNNEL ALIGNMENT,
AND PoWERHOUSE SITES
SEPTEMBER 1983
SHANNON & WILSON, INC~
Geotechnical Consultants
K-0631-61
FIG.2
r
L
r
l
r I , .
[
[
[
l
~ , ,
I
1,
KACHEMAK
BAY
, ,
,r-\
.,'
'. ,
~)
.. j/
( \
NOTES:
, ,
11 See Figura 1 for location of geologic
hlap.
21 Topographic bUe from U.S. Army
Corps of Engineers. Contour interval
is 5 f&&t.
\
\
\
\
E£1>,. \
j
011-15
·~~:i·
~ '-... -~~ ____ --·~--""1 i '
,
, \ " ~
\ ' \ \, /\
\._ .. -........
.. ( ..
/ ! f . , '
I I
f i
,
/
( / I
j ,
i /
I
\ /
! I ,I
i.
.... -----------
-_. ---~---.:...-~
i
I ' ,
~ I
! \
, \ \
,
j I
/ ,! I' ; I
. " " ',! "
/' /
/
o
I
,00 . 200 -
/
/ ..
I
f
400
I
>-\ \
!
i
SCALE IN FEET
! i •
,
J
: I
600
I
800
!
-'" ~
; ....
/
/ ,.-
i " i //
) \ (
, , ' (
/:" , ..
) .
'" I-w
w
:t
'" o
I-
w
Z
J
:t
()
I-..
:I!
Qa
Kg I ~ <J Ii
Ka
Kaf
Kag[TI
Kd
. . . · . ~ . . .. . · ~ , , '.' · , . .
--
~85
Xo
~
DH·17EX
~
Tp·l
EXPLANA TlON
QUATERNARY DEPOSITS, undifferentiated; Includes glacial
outwash, till, and colluvium. Shown only in vicinity of Intake .
GRAYWACKE; massive, weakly metamorphosed sandstone with
minor argillite layers.
MASSIVE ARGILLITE; weakly metamorphosed siltstone and
very fine sandstone.
FOLIATED ARGILLITE; Penasively sheared, weakly metamor-
phosed siltstone and very fine sandstone with less than 10%
nodules. boudins, and discontinuous layers of chert.
FOLIATED CHERTY ARGILLITE; as above with 10-20% nodules,
boudins. and discontinuous layers of chert. Includes a few layers
of fractured, massive chert to 10 ft. thick.
GRAYWACKE & ARGILLITE. undifferentiated; complexly mixed
assemblage consisting of 50·65% graywacke and 35·50% argillite.
Argillite is: predominantly foliated with less than 10% chert.
DACfTE DIKE; weakly metamorphosed. fine grained, porphyritic
intrusive rock.
Rock not exposed within about 200 feet of tunnel'alignment.
Lithology inferred from more distant exposures, topographic ex-
pression, and/or adjoining rock across ltructural trend.
Rock exposed withjn tunnel alignment corridor or within about
200 feet of tunnel alignmenL
FAULT; approximately located, showing rake of slickensides
LINEAMENT; approximately located
LITHOLOGIC CONTACT; approximately located
STRIKE & DIP OF FOLIATION
STRIKE & DIP OF JOINTS
Shannon & Wilson
BOR ING LOeA TION; arrow .how. orientation and horizontal
projection of inclined boring
U.S. Army Corps of Engineer,
BORING LOCATION laH borings in mud flau not shown)
TEST PIT
LOCATION
STONE &-WEBSTER ENGINEERING CORPORATION
BRADLEY LAKE HYDROELECTRIC POWER PROJECT
RECONNAISSANCE BEDROCK GEOLOGIC MAP
Of THE INTAKE, TUNNELALIGNMENT,
AND POWERHOUSE SITES
SEPTEMBER 1983
SHANNON & WILSON~ INC.
Geatechnical Contultantt
K.()631-61
f1G.2
SHEET. Of III
•
i
SHANNON & WILSON. INC.
GEOTECHNICAL CONSULTANTS LOG OF BORING BORING NO. Sri 83-1
(mTr~ STPJ.JCTUF£)
BRADLEY lAKE HYOROELECTRIC ?O'.tER PROJECT
CL I EHT
STONE & WEBSTER ENGINEERING COR?ORA!!ON
SIZE INO THE o~ BIT
DArE STARTEO
,
H(hWL MiD 1I(;,l!l OW10ND
I CORE f DOTAGE
28.4 ft. 126.9 ft.
7/11/8:-
I DaTE CCMPlETU
OEm I lOG ClASW IcmOH OF UTU,AL
I~ fIET (O~SCRIPtlOij) I
7117/83
I JOS HO, K-631
LOCHION (CO~RO'HmS OR nmOK)
N 2.103 474/E 342.987
~FR. OES'GHAiIG~ OF GRILL
LONGYEAQ 38
DIRECTlO~ AND l~tLIKUIDK tF HOLE
Tum DEPTM
155.3 ft. I TOUL CORE RECOYEUT. ~ 94.8%
! U~PLE ELEY. N UEt I BQ~ \ IN mT I 0lI RU~ S Rnil ~Q. , ,
::" .. ~;:.i~an"-' ;>RAVELS with cO::ib 1es and boulders. Composed 1094
I SHEET I
! ELEHTlDH
i
I TOTH ROD, $
45.6%
lEIlAR~S
1094 ft.
::. ., .. _>jnd10l Y of graywacke gravels "11th argl11,te fl"aD-
-_ ..... ment~, Subanpular to angular. occasionally
,.. •• '.. sub rounded ,
~:: 1:'.0 ~;&~;,~.~~:~~·'ir-______________________________________ ~
r-
!="
1 42
JA I Runs 1 and 3: silt and send portion
genera lly wuhed bW'Y duri ng cor; ng,
~ -[ 10S5.S
::: • ..1 .: "::"J ;'GRAYWACl(E BOULDER
::::.. ~ .. ~~l/if,t(,"
__ ~Ib:$e
I (\ o~.
-20 20.5 P;.t-L -------------------+1079.S -= :: :~.JSa"dy GRAVELS with cobbles. Subangular, scme =-": • 'Ipleces subroundea to rounded.
-
Q ~ ~,
_ ~ (ll) 0,
r-28 4 ... • ~ 1073 9 r-. ,,',.,. Mod. MrC! to hard GRAYWACKE; (lray. fir,(!.grained, . t :'l) ?;:":> IMHive. Catacldstic texture "lith ioeal fluxion r-". structure cMtiljning str1r.~ers and porphyroclasts ~:':::": ::: of mass i ve to 1 oea lly fo 1i ated api11 i te. Ca lei te f:" .:<"i.'. ':, stri~gers and veins are co"£,\on. Very Closely to
I-'c">,,,· closely jOinted. Fresh ~o 51 ightiy weathered. ~ liD 39.6 p~t------------------__tl066
~ ---
-so --
::->-
f:.. 60 r:.. t:.
--
-70
=----
-80 -,...
f:" r:-
-
~ 120
I Moderately narO to hard GRAYWACKE and ARGILLITE.
mixed, Light gray to aark gray. Argillite is
massive to locally foliilted. Cauclastic texture
with local fluxion structure, Calcite veins Ire
common. Closely jointed, locally very closely
Jointed. Fresh to 51 ightly weathered. Below
S4 feet joillts are close to modera.tely close,.
Hard GRAYWACKE. wi th zones of mh;ed ar'li 11 i te and
graywacke; Gray to biack, ~raywacke is massive,
fine-grained, argill ite is massive to ~oliated.
Cataclastic texture with lecal fluxior, structure
where argillite occurs. Caicite stringer, and
veins are COlrnlon. Closely Jointed, loc"l!y very
closely jointed. ~resh to 51 igntly <o;eathered.
1043.7
1019.6
FIGUfE 3
f-
2
3
4
~ fo-5
fo-
l-
f-6
l-
t 7
f-
8
9
:.. 10 I
r-! ! I
1
!--12 -
f0-il
'-' -r-!4
fo-
I-lS I-
i
I
I
16
17
18
19
~ 20
21 ,..
~ 22
44 :--,
Nil I
I
2
§.Q.
NA
31
NA
3
B2
ilA
100
""'IT 4
100 ~ o.
100 5 1100 % gray returns during coring of
2b HoedrOCk
100 i
j! 6 !
i
1°.° I 60 7
100 -;)4
8
-
100 9
32
100
12 i 10
10C -~
loa ~ 22
100 !
12 24
i
Z7 I ~ 100
22
100
22 ,
100 15 i
73 !
100 ,Reduced to Diamond coring J
% 16 1"4•3 '
BORING NO. 5\-1 33-1
I
i
I
SHANNON & WILSON. INC.
GEOTECHNICAL CONSULTANTS
PfUiJECT BMOLEY LAKE HYDROELECTRIC PO',IER "ROJECT
LOG OF BORING BORING NO. Sri 83-1 (caIT.)
(JtrrpKE STRUcnJFE)
I JOS NO. K-63l mn 2 OF 2 F-----------------------... ~----------------~--__ --~--~--~------_4~~~--------~ ;lim LocmCM (CQOl!OINATES OR SHilOH) mVHlOM
STONE & W£BSTER ENGINEERING CORPORATION N 2,103,474 E 342.987 1094 ft.
DRilLIKG comn
ARCTIC ALASKA TESTING LA~ORATORIES
sm I~O mE OF BIT DIRECTlQM AMD INellNHlON Of HOLE
I eo.aE fOOTAGE TilTAL OEm
nmmmn
DmH
lti FHT LOG
7/111133
OAT! CO~Pl£TED
I
CLASSIFIWIGK OF MATERIAL
(O£SCR I mON)
7/J 7}1J,3
I £lEY.
, I~ FUT
::.1 120 I':N;'.:',< l:ard GRAY"AC:~£. as aocve
-124. 7 ~1?~:;/;;'#;--'-~--'~:---:----'---'---:-----ILO05.8 -, ~f~~ Hard GRAYIIACKE; gray, fine-grained. massi~e. _ 'f.; Catacli'stic texture with sand-sized clasts of
_ argillite and local fluxion structure with
130 string~rs, wavy bands and clasts of argillite.
~ CalCite veins are COf11(,lon. Moderately ciosely to I:: 135.0.. . !tloselv jOinted. Fresh to slightly weathered.
f:.. rloderately harn to hard GRAY'iACKE and ARGU.I.ITE.
~'ltO mixed; gray to blaCk. Grayv'dcke is r.\usive. fine-
1-' grained, argillite is foliate':. C .. taclilstic f:" I texture vlith co,,,;;oo flexion structure of porphyro-~ ,Ii clasts and interlayered wavy bands of the
~ ll~l~th~o_l~o~_l_e~s~.~ __ ~~~~ ______ ~ ____ ~~
1 99B •S
:-150 '/MOli. hard to hard GRAYWACKE; gray. fine-grained, \
'" Imassive. Cataclastlc texture \filth scattered
::-152.5lli)sand-SW:d clasts or argl1lite, local f1\Jluon 986.2
:-_ structure with strlngers and 'levy bands of /I.
-15~.3 ~arqi111te. Caleae ve;ns are com.,on. Closely 198 ,.2
,.... i \jointed. fresno f:-:60 "---------------------'
i=-Sottor.; of oxplol"aticn
f::-
f:' I---' -
~ ...... ;:..
C-,...
~
'r--~
f:' l-
I=-
l=-
t---
.:-----
~,
:1
bi
f:-i-
I---
~
I
i
! ,
I
FIGU!t 3
r-
I-
-
E
-:-
f--
l-
I-
i--,
f4
l-
I-
l-
I-
I--
i--
l-
I--
I Tom em RECQY[U, "
24 I ~ 17
I ;-:l
76
25
26
27 ~ 19
100
'"4i I--
r 100
8b 20
28
29
I I
I
I
I
I I
BORING NO. SW 83-1 (coo,)
I
SHANNON & 'tillSON. INC.
GEOTECHNICAL CONSULTANTS LOG OF BORING BORING NO. Svi 83-2
(BPAlUY RIveR FAUlT)
::..
::.
--
PRDIECT B~ADlEY lAXE HYDROELECTRIC POWER PROJECT
CU£HT
$1O:,E & WEBSTER EtiGINi:ERING CORPORATION
DRlum C~PU!
ARCiIC ALASK~ TESTING LABORATORl~S
sa IL fOaunt
3C,3 ft.
DATE smm 7/20/83 l Dm CQHI'tETED
eErTH
!N HET lne CLASSIFICATION Of MATERIAL
(OESeRIP! iON)
Gri!velly :;AND ,lith cobbles ana boulders
7/28/83
-10 Cobbles are more CO[,\"iIOn belaYI 10 feet
4" rounded GRAVEL with trace of stria.tions
recovered for Run Z
dod. hard to hard CHERTY ARGILLITE; dk. gray to
clack, foiiated. Catacla.stic texture with
loc.l fluxion structure cO:1tdinin~ high percen-
tage of chert. Close1j jointed. ;'resh to
slightlY weatherecl.
Chert generally constitutes 10-20% of rock, with
local zones containing up to i5% chert.
$f:EAR ZONE. Argill i te \:; th chert porphyroclas ts
locally brecl"iated witn rock fragments in silty
sandy matrix.
1:6J, harti to hilrO C~:ERTY ARGILLITE, dk. gray to
blaCK, follated. Cataclastic texture with
porphyroc14sts or chert 3n·j graywacke, lOCally
with fluxion structure, 10c<ll concentratrations
0',' chert porph;/roclasts are cOF.ll\on. Closely
jointe~, locally very closely Jointed. f'res~
to slightly weathered.
~elow 88 ft •• elon'lated S<lfltj to cobble-sized
C 1 aHs of fil1e-gro j ned graywacke are COQ',lOn.
! JOB NO. K.OS31
l3tATI D~ (tOQRD I Hi YES OR SHr I D~)
N 2.105.531! E339.684
I SHEET ! OF 3
! EtEH T I O~
1535 ft.
IHR. DESIGKi.Yla~ OF DRILL
LONGYEAR 38
UIRECTION INO IHClIM£TIOM OF mE
nEV.
IN fEET
1535
FIGUrE 4
I 22
,NA
!
I 1
1
TOTH ~aD. s
32.4~
3egan f:Q3Wl diar.:ond coring at
surface
Kl.mS 1 and 2: cuttings are consh-
tentl; sUDlnsular f.e. sand ftnd
f. grovel. Silt not signHh:.lnti:;
present, wasned away. Jril1er
suggested that sO.:e ~~arse ';<Her;al I
is "pushe(i" out of the w.y by core ..
barrel. '
2 3 Drii 1 act ior. 1 nd; Cd tes rE! I at we 1 y
NA CObb])' material oalow 10 ft.
,..
'-3 ,. 100~ or; 11 water ret"rn. in uedro<;1<
1-I~
Cr-J-----~~~~~
1-" 100 i 2 i 1 C-t------~-~-' I
5 100 H
t:J-__ --;.~i 3 I
6 ~ 100 ! Tn, EJ 40 @ 55.7 ft. co,: .. e;'teo to f'4\.1D~ cO;.-
H 7 "0 4 'ventional dia ~.oncl corin?
t:::.J-.' ----+-.........,
r.:r-----8 --+-~"--i~ I
100 S o
r--10
f--6
1-1-----+---1
i-11
12
14
15
16
18
19
20
10
100 ;sf--
l!jf 12 i
BORING NO. SH 83-2
SHANNON & WILSON, INC.
GEOTECHNICAL CONSULTANTS LOG OF BORING BORING NO. 51rl83-2 (CaNT,)
CBRlillY RIvER FAULT)
PROlECT I JOS NO, K-0631 i mET 2 or 3 BRADLEV LAKE HYDROELECTRIC pmiER PROJECT
! eli EKT STONE & WESSTER ENGINEERING CORPO~ATION L~Cu!O~ (C~QRD1~H(S ~R SHTIOH) I ELEYA!!~N
Ii 2 105 531 I E339 684 1535 ft.
OR ILL ! HG C~lIP ANT ~fR. DES'CHHIOH Of DRilL
ARCTIC ALASKA TESTING LABORATORIES
SIZE ,HO 1m Of BIT aUECTlO~ ANO INCLINATION Of KaH
so I L fOmGE I CORE fOOTAGE TnTAl DEPTH I CEPTM TO WATER
DATE STARTED I om CO~PLmo ! Tom CORE moym. $ I TOfU ROD. $
DEPTH
I
ClASSIFICAliON OF ~HEilIAl I Em. SA~PLE I I! lOG N Ull,B:U, RE~U~S I~ fEET I (.rseR! PT I G"l Ie FEET OR RUN ~ Rao • NO. i
~ 120 'ItH,11 i-20 I
t=-fr t Moderately r.ard to hJ.rc CHERTY ARGILliTE, as above 100 12
f:-! '(1 • (~I, 21 JO -
1:-' 11/(11 ' ~ ~ 130 ~i~Qi 22 leo 13 I
I ~
.~ 100 ;::-lJ\~lt, I 23 r--\\)\\~\ -32
f:"" II/riD' 24 100/0 II; :; 1:<6.3 ft, co,werted to NWD 4 ~ l3G . 0 ":.\.'.. '\~ 1437.4 , ~~ 10010 ; conventional diamond coring
I-14C ~~ SHEA/< ZONE. Argi 11 i te \~ith porphryoclas ts of
:: ~ chert. f'reQo.ninantly fault t>reccia with nU[,lerOUS 100 --smaller lones Qf crushed rOCk and silt reare-26 0
::-~~ senti nl) a 11 stages of shear, ranging in hardness
27 J.Q!-15
::,
1
from medium harct to ver;( soft. Local1y frag~ents 0 are contained in a c1a~/ey fault gouge. 100 ~' 150 ~ r-28 0 ,.......-:
~ OccaSional zones of relatively competent chert 29 are contained within hi9hly sneared material. i l-i 96/0 15 t:-~ ! 100 l-I-30 ~ ~ ,..., ~ l§Q ,.--r-150 ~ I-31 l:-I r:... ~\ I-100 lii
f:. ~ I-32 0
f:-I lOO r-170 ~ 33 \0 : -! 100
18
-~~~ :14 ' 0 I -176,0 fil/)(1f 1410.5 35 ~ I -:: I j'/I !'.odera te ly hard to hard CiJ.ERTY ARG! LUTE. dark Ill!l~ gray to blaCK, foliated.Ciltaclastic texture with =-i 36 i 100/0 19 :
~ lao J r-elongated porphyroc1asts of grayvlacke. local
I -zones contain concentrations of chert porphyro-37 clasts. Very closely to closely jOinted. Fresh ; -\vi{~ to slightly weatnered. i 84 @ 185.9 ft. converted co NQ 3WL
;:::-i,J{\L 38 'IT 20 "iar.lond cori n9 r-190 Chert constitutes about 20~ of rock. ylith
::1 {.\~{\~ occa, iona 1 local zones containing up to 70~ chert. -. :-l 39 I
c-I
197.0 \\!\{ \ 1395.7 21 ' r:... :.'.'.' J Very hard Cr.ERT; light gray. 40 100 I F--:<.;~ Catael astic 7i 200 texture with stringers of argillite and scattered i-~ -»>:1 clasts of very fine-grair.ed graywacke. Closely i-96 -... to fuoderately closely jointed, Fresh. f--41 " • G. ~ . , . -~ " ~ . 22
206.2 ' . l339.1 -~y.i· f\oderately hard GRAYIo!f,CKE. gray to dark gray, I-~ I -210 r{~/~:;, massive, fille-graineo. Cataclastic texture with I-42 I .... ' stringers and clasts of argi 1 i te /inC: scattered r
::-1+>'·:': Sr,ldll clasts of chert, Strin~ers and veins of r-43 100
-Cil 1 cite are COf>l;1on. Closely ';0 very closely 1-; "J1 23 jointed. 'res!:. -100 -220 1319.4 44 "'TI' r-----: -t <I"'" ... i Very nara CHERT, 1 ight gray. Cataclastic texture :i ~ «<~ with stringers of fo~iatld arg~11 ite Ind zones of 45 T! 24 ::-.. , cnertyargillite. Closely jotntea.' eresh to
51 ightly weathered. I-~8 -r-230 1'-'-'-46 "" t.. ~£
\ .. , 25 ;.,. . --r-100
l-I'"" 47 "TI 237 0 1367.4 l-":" :', Hard GRAnlACKE i-48 IOOn7 26 i 2~O
FlGUI£ lj BORING NO.SW 33-2 (cot'n,)
f
I
SH~~NON & WILSON. INC.
GEOTECHNICAL CONS~_TANTS LOG OF BORING
f:. ~ ~ ~ f:. ~ ~ --
:::
PRomT
BRADLEY LAKE HVDROELECTRIC PQI,(R l'RO~ECT
CliENT STONE & "EBSTER ENGINEERING CORPORAT:ON
DRILliNG CO~PAHT
ARCTIC ALASKA TESTING LABORATORIES
S lIE AHO TIPE OF BIT
OUE SHRTED
G£P1H I I~ HEY LOG.
240
.'
250
r .ii
260
I CORE roomr
I om CD~PLmD
numlCHiDH or UTERlAl
(GESeA I mON)
Hard GRAYWACKE; It. gray to ok gray, ,,,a.siva,
tine-\.rainecL Cataclastic texture l/itl1 stringers
and zones (If massivll to foliated argillite and
1 oca 1 nux il)ll structure cont. ioing cherty
argillite and co~ble-sized clasts of chert.
Closely to very closely jointed above 247.0 feet.
closely to moderately closely jointed below 247.0
rut. Fresh.,
CalCite stringers and veins are common in massive
graywacke zones.
! 105 HO.
j K-OE31
lOCATION (tnOROI~iTES OR SWIQH)
N 2,105,531 / E 339 684
IFR. OESICNATION OF DRill
DIRECTION l.llD l~tll~HIOH OF HOlE
TOTAt DUTH
I fLB.
1 IH FUT
46
49
100 26
bO_
50 ~ 127
~ 51 100
I-60 t l-----t.......:;;~ 2il
100
-g'4 S2 \;.~~\'i:D;
:: 262.3 P'""""""t-------------------I1349.5
:::
;:-.
1-:
~ r:.. f::. t..
Bottor.: 0·( E)(plcration
----
-::: --=-
r--
~ f:'" f--
~ F-~
~ ----
~
--,.... -
f:"' i-
i-
~
~
i-
f-;::.,
i-
i-
r:--
-I -
~ i-
I--I
BORING NO.SW 83-2 (CONT,)
(BRADLEY RIVER FkJLT)
SHEEr Of
3 3
ElEUTION
1535 ft.
F1GUf'E 4 BORING NO. S'~ 33-2 (CONi,)
f
. ,~~~I
;;~~3~
i::::;~~
SOil DESCRiPTION f..)
i::5 oe ....
Ill: Surlac; EI~vation: 2 feet c=
////
Med urn stiff, locai1y soft or stiff, ~;;;
clayey SILT, with scattered stringers;;
and thin enses of fine sandy silt, ;~~;
pockets and lenses of silty clay, and:Y/h
occasional zones of clean sand.
Scattered shell fragments.
Interbedded loose, gray, slightly
silty to silty. clayey, fine to
coe rse SA~WS. and soft to med i um
stiff sandy to slightly sandy clayey
SILTS. Random gradational changes
throughout. .Scattered she 11
fraoments.
~ ----~ ~-~ ---... """--............
Medium dense, gray, clayey, silty~
gravelly, fine to coarse SAND, w~th
zones of clayey silt.
II
. -. :c -ill>. ....
~
18.0
.....
-' a.. • C
"""
*lTI
2il
4ll
51 .1
23.0 7 ~
81
90
1O! -~-------------------~~29·.O ~~t
Medium dense. gray, slightly clayey, *13
5i lty SAND~ random fine to coarse 14
gradations with local ne gravelly ,
zones. 15 I
LEGEND
Grav~ I \Mlle r v lOllS SUI
UllltH lu,1
Frozen Sand PIUDlII0ter ! II!
=1iIIO: Zl.>.!
::31-e c :lIIl
. STA.NDARD -PENETRATION RESISTANCE
~ z, ( 140 I O. "'II I an !. 30" d,og) -Aillus per foat fiIb
~O 20 40
5 .. : .. ~ .. ~ ... -... -':'.':'_' .. L: I· . ~_'_'_'
e
10
15
20
...
I . .
.............. / ...... -....... --.;..-...... :...:-... -. --
[
I
J
I
f
I ....... "/ ........ _ .............. ......;. .......... _----
i .
\ . . .-\-..-~--~---.. ...
'I'
I i I / ...4 · 'j'
25 -"'~'-"-'. ,-.--'~.' --'~'-,--'
\' •.. , . ,
. '\ ; @ , . . .
~ I
, /1. ' . I
30 . __ ~~ .• -, , .-... -.~
I
J
5 ·-···-·~··--t····---··-·
• ~ Water content
IUU: The 51fatlflc~t·on !Ines represent
tn~ 11""Ulllilltt DounOlfiCs otl"f!le~ $0;'
typU ~fld :ne Itansltlon may O~ ~raC!ul!1 r-Grllund
~ ThUfII!lcolJ/!1 e Stone & Webster Enoineering CorD.
S I I t I z" ~,D. Sllill ~p\lgn UlilPI~
Clay 11 3" 0.1l. Ih I " .... 811 ump 10
"" Sllll!ll~ ne! '(tC:OHfUI
A 1 1m f bll f 2 I IIllI I!:
~Ila t r • I g;: L I qu I d 'I III I I
Organic ,~ ISUr conten'
Content Plulic IU!lIt
Bradley Lake Project
Barge Basin
LOG OF BORING NO •. S~~ -3
September, 1983 K-0631
$liANN!!W " III L SON. II'tC.
.lD!lCKIIICH tOI1lSu,U~TS
FIG,S
';':;:;:;;i
SO I L DESCR I FTI ON
Surface Elev;ti6n: 2 feet
Medium dense~ sliQhtly
silty SAND, as above.
Bottom of Exploration
Completed 8/2/83
clayey~
Torvane Tests
~th (feet)
6.5
24.3
27. J
Shear Strength
0.9
0.24
0.36
( tsf)
Pocket Penetrometer Tests .
Depth (feet) Compressive Stren th(tsf)
6.5 3.0-3.25
24.3 0.5
27.1 La
Vane
Depth (feet)
7.2-7.8
10.5-11.1
Shear Tests
Shear Stren
Natural:
Remolded:
Na tura 1 :
Remolded:
loca ti on: N 2,111.590
3~1.840 E
LEGEIHl
th (tsf)
2.32
0.27
0.73
0.14
~
:II': gJ Le
.,.g -'
is
C'&I
Grave I ~ \mpUYIQII5 nat
! lUlu lu al
frozen Sana PIUOffifi!H I I D Ground I ~ Thull!(leOLlP!~
, -. = I-
L
!.OJ
CI
Si It I 1l.1l. !pl.1 spoon sam I) Ie
11 J" 0.0. In I N-.. a I I umpls
Clay 11-Slillllli e ~gt raerHertid
AltUl:!lfg 11m I \~:
Pea t ! • 1_ L 11'111 i d I lIi1l !
Qrganlc ~lfl2ar eonUnt
Content Plutlc 1'!fII!
..... graB
...J lI'C ..... "'-=-:l!II e"", c ::;l!IIIi' ..-:
161
, -STANDARD
PENETRATION RES!STA~CE
(140 1 b, "* I II" t. 3D" d rOD)
A IIIG"s ~iH j Il~ t
20 a.
171
40
~v
• ~ Watsr content
HOU: The str!t. t IC3t! on • ,n!s reoresent
tne ;ppraXII\HIU OQundlflU O€\lISfee S~li
typeS ~na the tranS.t.on :n~y Oe irSdu~!
. Stone & Webster Engineeri Corp.
Bradlev Lake Project
Sarge Basin
LOG OF BORING NO. SW 83
(Cont.)
SeDtember, 1983 K-0631
SHIINHDN , iiLSQIl. IHC.
'[Of[CK"ICAl CO~SYL!ARY$
FIG. 5
SOil DESCRIPTION
Surfaci Elevation: 2 t
Gray to dark gray, slightly clayey
to clayey SILT~ with Dockets and
layers of silty clay, scattered
stringers'and thin lenses
sand. occasional zones of clean
, -~ STANDARD
PENETRiTIOW RESISTANCE
% (l40 ItL Wltlnt~ JO il drug)
:: ABI~ .. tPerfag!
~ G 20 40
lO~ .... ·.-.-.. --... --.·--·?···-···-----,--·-,--~
Dark gray to black, clean, fine to ::<:,,: 14.0 II
coa rse SAN D. t ra ce 0 f fine ~g_r_a_v_e_l_·~.......,r~~:~J~~11,.;;;~i~i 16 . 0 3
Bottom of Exploration
Completed 8/3/83
De p t h (f ee t )
3.6
10.1
16.0
Pocket
Depth (feet)
3.6
10.1
16.0
Torvane Tests
Shear Strength (tsf)
0.46
0,45
0.3
Penetrometer Tests
Compressive Strenath(tsf)
1. 25-1. 5
1.0
0.5-0.75
Location: N 2,111,593
E 321,839
Frozen
GrcH.wd
LEGEND
Gravel
Sand
S i I !
Clay
Pea t
Organic
Content
r IIIlIHHVI OI.lS U31
hlu IlIivG I
E 'le~~mellr liP
~ Th8rmDc~uDl~
I 2" O.D. spilt ~pOQn saMple n: 3" O.t. tn,n-"all ump'G
lit SOIIIlI) I ~ nol reto.ued
A tie F bG r g '1!Ii I IS: 1-. 1"ilI LIQUIC I Ifill t
~:: '/lIter conllnl
Piau Ie I,mll
20 4 • ~ Water content
NQle: T1H stratificatIon IInu r!oreUnl
\n~ !ppfo.,m~te Dg~ndar!es o;tG$e~ $QI'
typeS ~no !!'Ie tf~nslt,;n may oe ir~al.!~'
Stone & Webster Enqineering Corp.
Bradley Lake Project
Barge Basin
LOG OF BORING NO. S14 83-3A
September, 1983 K-0631
SHANNuN & III LSOI'1, IHe.
~(OYEC~.ICAl CO~SUll'~fS
FIG.6
SHANNON & WILSON, INC,
GEOTECHNICAL CONSULTANTS
FROHer
BRADLEY LAKE HYDROELECTRIC POWER PROJECT
LOG OF BORING
Joe KO.
CLIENT LOCHION (tOORDINATES DR SHTlO~)
BORING NO. SrI 83-4
(BULL ~YXlSE FAUlt)
I mET 1 Of
2
STONE & "EBSTER EtmINEERIliG CORPORATION ~, ? lOR 500 IE 333~12 ! ElEHrm
i235 ft
GRtlW~ CaNl'U! m. B£SIGMHIOK OF DRILL
ARCTIC ALASKA TESTING LABORATOR!ES IONGYEAR 38
'11' '"' r 06£ ~r °l·! DIRECTiO~ AND IHCLIHUIO~ Of KOLf. "aDOu Q 45 0 • '"." " v.. HQ,WL. NQ,WL, '11404 cOI~~~VE:::N~T':;IO~N~A::'l ______ -+--::::::,:,:-:;= ___ ~ ___ ",:,:,"r~"';'~·~;;:;;T __ ----1
I -TOT" "[Pl" D[HM TO w.m so I L fOOTAGE " CORE IOQUCE . ••• n
4.2 ft, 2Q2.1 ft. 206.3 ft. 3.5 ft,
I am CO~'WEO I Tom CORE RHOVERY. $ om STARTED 819/83 8/17/83: 99,5~
OEm
1M FEET bOG CLASS! F I cm D~ OF ~A lER ill
(D£SCRlPTION)
mv.
I" FEET
"'" I !2J~.() POl" ~ <iii ~·~··4'~·'~~ __ ~~T~O~P~O~F~RO~C~K~~~~~ ____ ~~ ____ 1123Z.0
4.2 Moderately hord to hard GRAYwACKE; greenish gray, >, fine to medium grCcined. Cataclastic texture with
porphyroclasts of graywacke and ar9il1ite commonly %. elongated alo09 shedr foliation, local fluxion 8V structure of folIated argillite contains elongated,
chert clasts. Numerous stringers of argillite,
scattered calcite veins. Closely to very closely
jointed. Very slightly weatnered to freSh.
24, ..."......,.,----,.--~--;--,~::-::":_;:;:::--:-;-......---_:;;__:___t1217 . 6 Medium hird to hard ARGILLITE; blaCk, very fine
grained, massive to weakly foliated. Catacl!stic
texture with porphyroclasts of gr~ywacke and chert
hscattered c~lcite stringers. Closely jointed f 1213.4
jwith local clay fillin~. fresh
30.6
MOderately hard to hard ARGILLITE and GRAYWACKE,
~ixed; blaCK and greenish-gray. Cataclastic
, texture with shear folilltion dnd local fluxion
structure. litholoqies are tectonically mixed
and occur as porphyroclasts and stringers
elongated alonG foliation. Scattered chert cl~sts
to .Z feet did .• local chert layers to 1.3 feet
thicX. Closely jointed with local caJclte and
49 5 . pyrHe f1111naS. . "\\ \\\
1'). l'l Jointed. rresh.
1200.0
\~~l~:~ l>Ioderately hard CHERTY ARi.'iILLlTE; bhck, fol1ated,
I ~\\ '\: £ataclastic texture w1th porpl1yroclasts of gray-\l~I\. ·I!dcke, l()c~l fluxion structure. Moderately closelj
1
\ \1 '\\ \
il/\I·ilili\\i •.. Chert constitute~ approx. 30-40% of rock~ass, with 1
1191
0
6Z.2 ~ Joca! zones rang1f19 from 10·60%. r .
64.9 ~ 'iery hare; ChERi; light greenish-gray, massive. f 1109.1.
\Cataclastic te~ture with stringers of foliated I
\argillite. Very closely to closely jointed. I
-
-100 -
~ F t-
\Fresh, .
Hard ARGILLITE and GRAYWACKE, mixect, greenisn· I,
gray ~nd black. cataclastic texture with shear
foliation and local fluxion structure; porphyroo
clasts of graywacke and chert in argillite layers,
and stringers and porpl1yroclasts of ~rg111ite and
chert in graywacke layers. Very closely to
closely jOinted. Frei~.
Loca 1 zone-s conta in up to 301 chert.
!\'hl \ Hard CHERTY ARGILLITE. dark grey to black, \~\\(II foliated. Ca'taclastic texture ",ith ~c~ttel'l!d
\,\\\\'\ PQrpnvroclasts of graywdcke dnd loc.l zones .of· ~ chert with llite stringers, Closely JOlr.ted.
.; r{res igh 11 we"t~er!!c. !
f ,'?'" liard MGILLlTE; gray to ,ddCk, massive to foliated,
\:.::.: Cdtacldstic texture 'yith porphvroelasts of
.~ graywacke and chert, numerOJS calene stnngers.
r-110 ,::it.. local pyrite r.nr:erd·l2atlon.
I-',,:,f" closely JOlntec, ~resh.
very closely to
I-Chert constitutes 5-10. of rockmass I=-116.3 .lones. ~ /',;.
i-120 j,! ~ord GRp,YWACKE
in localized
RENAUS
~I 1100 Beqan Hf13 wi re 1 ine coring dt
1 . 1 surhce, "dsh~d to top of rock. ~I--___ +--:Jb __ -..; i no sample
1 Water loss 7.5-8,0 ft., olugoec
-2 : ~ ~I with cuttings
,_ 2
r-3 100 I ,
t:1-J--__ +-b9_9.....,~
4 iDa
"'42" J I
~~----~--~--~ r-100 ~ 5 -:IT
1=-1-----1--''-'--; 4 . ~Iater loss at 2(1.8 ft., probably
I-5 ~ H due to plugged bit
f-
.... 1
I--
l-
f-
~ l-
I-
1-.
I-
a
9
10
11
12
13
14
15
100 5
-57 100% water returns ~low 29 ft,
100
13
I 100 I ___ _
80
100 -n
100/53
100
~ 47
! 100 ;;
100
, -s1
98
~.,..-
J~
100
48
10 0
100
90
100
~
100 --rs-
-100
37
100 -8"!)
~
7 :
~
8
9 I
..--
10
i-----;
11
f--!
12 :
,
H
I is:
I i
\
14
-
15
,
ocr ' i! 100 16 i
1:1----+-:7:"'--1 i I ~ rm Switched to NOI,L with H~ cas; no
I
SHANNON & WILSON. INC.
GEOTECHNICAL CONSULTANTS LOG OF BORING BOR ING NO. Sri 83-4 (CON:,)
(BULL tmsE rAUL!)
r PROltcT I lOB NC. I SKEET 0' SRADLEY LAKE HYDROELECTRIC PO',iER PROJECT K-0631 2 2
tL lENT lOCATION (CnD~nIKms OR mTlO~) I EWHIOK
1235 fL STONE & WEBSTER ENGINEERrNG CORPORATION N 2.108.500/ E 3~3,O32 i
3RIlliMt CCBP!RKtTlC ALASKA TESTING LABOARTORIES HR. DESIC~HlOij OF DRILL
SIZE A~O Tm OF m ~IR£"TICH ANO lHCLIUT10K OF HOLE
SOil FOOTA"! I CORE fOOTAGE TOTAL OEPTH I DEPTH TC U HR
DUE SIUTED I om COUPl.EHG I TOTH COllE RECUYERY, $ I TOUt ROD, S
DEPIN LnG CUmFICATIO~ OF UTUllL I ElEV. SU?LE H S REt SQI R£IIARKS I~ HET (DESCRIPTION) 1M FEET OR RUN iiiiiD NO.
=: 120 Hara GRAYWACKE; grayish oreer., fine to r.lI!dium-i...
r-=-grained, low-grade metar.lorDhosed, massive to I-26 lOG ,17
r= foliated cataclastic texture wit,) porpnyroclasts I--n I--of chert, argillite, and graywacke. Loc.l fluxion ~ structure, scattereo calcite stringers and I-27 lDO I-130 pockets. Closely jointed and fractured becoming -W 18
f-
Itt
very clost:ijl fractured below !J3'. Fresh r-I=" 28 100
Ji I-19 I ~ 138.1 ;1;/ ,'" Hard ARGILLI it:; black, very fine-grained, low-1137.3 ! 100 l:-'l40 grade I!l<!tamorpnosed, massive to fol iated, cati!-29 W ~ ~ ~:~? c hn ie tel( ture wi '", argillite and chert porpnyro-
clasts. Very closely ,;ointecl and fractured 30 I 100 ' 20 I f-,
'c:. 145.9 n32.0 1 20 I
~ SIlEAR :CtlE; brecclated arf i11 ite and oray.:acke. t:.
! t-96 i-150 locally sheared to gravel y silty sand. Else-31 r:. ~ where rOCk '5 soft to meoluffi hard, highiy 1--1 ;0 21 ~ fractured rock franments heid toQether with t:. ,.... t\ selvages of silty cioy. Local gauge zones 0.6 f[ t:-154.4 • •• thl ck. 112S.a 32 100 r--I-. ... !-44 1-. • .. A ~
~160 .;.;.;., Soft to ::tedium hard CKE!<.T w~th very hard rock I-100 . 22
" • , •• fragments; It. gray, highly fractured chert in r J • Tf , . , arqil1ite.matrix, catac13Hic texture, argillite
~; matrix is commonl,)' slickensided, local shear 1--, 34 100 23 ~ . , . zones of sandy silt sized ar9il1ite. Very closely I--24
I--'" ~ .. .. ;ractured. becoming closely jointed beipw 164.5
)--feet. FreSh. lOQ i---~ 170169.5 1115.1 35
il
\\ I-59 I Hard to very hard CHERTY A!<GILLlTE; It. 9ray to ,... 24 I-)r .~ 1= black. Cataclastic texture ",ith porphyrocldsts 36
of chert and dac He 1 oea 11 y, lOtle of mixed ;
~ arr.il1ite and nraywacke from 173 to 183, scattered 37 1001213 I i-calcite veins and 5tr~noers Chert locally t:. 180 li t~ constitutes 60 to 70" of rock. C: ose 1 y to very V 38 l~~ 25 1-' closely jointed and fractured. Fresh. -f\ ~ ~~ \Ilt
!-,....
39 100 t---May be disturbed oy dri 1 ~ ing
~ -ro-
t-196 88 .8 1101.5 88
~ (:j~ Hard GRAn:ACKE; liljht greenish qray, fine to'1Pf'i. 40 i 'l.1 25
!-qrainea, massive, !'l1Xed YlHr. argillite belo., ,
196.4 ft .. Cataclastic texture, scattered calcite 41 100 SwitChed to~WD4 conventional !-,.... I--drilling stringers. Closely to very closely jointed and Tf ;:-fractured, numerous 51 ickensiiJes. Fresh. !-I--42 ' 100 27 I
i-ZOO r-i -S'S' ~ I-201.1 " Wn.7 r-~-Hord to yery hard CHERT; It. qray. C~ taclas tic 43 98 texture with tringers of mDderately hard foliated r-IO ::. 206.2 ~.' :> c~erty drQilliU. Close 1, iointed. Fresh. 1089.2 ~ ~
f-210 B07TO"l OF EX?LORi\TlO:; r-~ r-
I--I-
~ l-
I-I:. Z20 =-i §j H
I-! ] --~ -230
r-
~' ~ I ~ I-2~O I
I
FIGURE 7 BORING NO. SI1 33-4 (COI'll.)
,
I
:
'"T1
H
Ci1 .
00
SHANNON & ~ilSON. INC.
GIGI~t"~irAI CO~SUlIAe,s
FIELO LOG OF TEST PIT
SOIL DESCRIPTION & REMARKS
ElJ-loose ~ brown, s i 1 ty 9 sandy, O~D gravelly BOULDERS (angular Dacit~
cobbles and boulders in silty
sandy soil with numerous roots.)
Moderately hard to harci 9 greenish
gray, fine-grained porphyritic
DACITE, closely jointed,
moderately to slightly weathered.
C) oo:: § '" ... C <C =: III< <!>l
-0
G1 > 'I.. w
If)
..0
0
OJ c
0 z
"" ....
....I
~ ~
""
1::-
OJ ..:.e m
I-
+>
0 z
t-
~w &-ow
4."-....
.::IE
9
6
HID NO.
PROnCT
lOCATION
K-0631 .. < BAlE August 8, 19831"5PE&IOI_O_0_C1 __ ,, _______ _
Bradley lake Hydroelectric Power J)rojefJ ________ -:o-_
Powerhouse; N 2,l12,579/E 321,271
78 ft.
3
SAMPLE
NO.
R-.31
90
80
10
l-
I
~
W 60 s:
>-III
IX: 50 w
!: u.
I-40 Z w
U a:
W
IlL 30
20
10
(I
8 M
158.9-
159.2
8 gg
N ..
U.S.Co
8M
SIEVE ANALYSIS
, I
"
, , ,
0 ~ g .., o Il9 III " I') I'< -III! II! "t 11 ~ <!) N ..
GRAIN S9ZIE IN MII..UMETERS
FiNE
-=
ClASSifiCATION
~ Gray, clayey, siltYf fine to coarse RA~~
(fault gouge with rock fl:-aqments)
~~ ~ ~ q
L~:~-
NAT. U. w.e. "
8 18
HYDROMETER ANALYSIS
I'll q
~:
PI-
13
GRAIN SIZE IN MM
~
Pi
5
10
::10
FINES =~~:~:~::::_::: ----.J
stone lit \'lebster Engr. Corp.
Bradley Lake project
GRAIN SIZE DISTfUBUTiON
Boring sw 83-2
Sept. 1983 K-0631
SHANNON lis WillSON. INC~
Geo~lIc;hnlclI!l ConsulUntli FIG. 9
SIEVE ANALYSIS HYDROMETER ANALYSiS
SI:£IE OF OPENING iN INGHEIii NVMIiIER OF MESH PEn INCH, U.!!.. ST .... NOARD GR"AIN SIZE IN MM
~ ~ ! o \!l ~ N ,.. :8 ~ ~ (') N 0 Q 0 q c & N 0 00 0 000 q q q ,.,. ID ., M N ... 'It ... N 'If IN • " ... 100 ----. 0
90 10
80 20
10 30
l-
I-X
::t ~ !2 ~ w 60 40 s: )-
)-III
m 0::
II: 60 50 w
UI I/)
~ IX « u. 8 I-
Z 40 60 I-w Z U w a: u w a: I). 30 70 w
0.
20 SO
10 90
I} 100
8 8 gri: g !i ~ 0 0 !Kl 'llO ~ I"l N .. i!! II! "t I'! 11 '":~ ~ ~ M !II q~ 8 ~ S S ,...
N .. q q q ~ (") iN ... GRAIN Size aN MU .. lIMETERS q q q
'" SAMPLE DEPTH-FT. u.s.c, CLASS iF iCAT iON NAT. U .. t'l. PI NO. W.C, " Stone & \\"ebster Corp.
S-2 4.5 .... 5.0 CL-ML A Dark gray, clayey SIL1' to silty ClAY, 24 27 21 6 Bradley Lake Projf~ct trace fine sand GRAIN SIZE DlSTfUBUTION
24 Boring SVJ 83-3
8-7 22.9 .... GM ~ Dark gray, slightly clayeY9 s1 lty, fine NP
23.6 to coarse gravelly, fine to coarse SAND sept. 1983 K-0631
SHANNON & WiLSON. iNC ..
G IHltltchnlclJ!1 Consulilllnts
SAMPLE
NO.
8-9
8-16
N ...
100
90
80
10
f-
J:
CI
iii 50 ~
>-III
II: 50 w
~ u..
I-
Z 40
III
U a: w
I!>. 30
20
10
(l
8
M
26.0
35.5-
37.5
SIEVE ANAL '(SiS
lilU OF OI"IU{~j-IG IN !HCHn :: II'IUMI!I£R O!':M:!ESH il'IUI IHC~. u,s.: ST ANIOAno
<II '>!' 1'1
8 gg
N ....
u.s.c.
8M
8M
N
g
g :!: ~ l! Q :'i: 0 g -"" <1 ... ... <I'
~ ?l 10 0 W !II.l l' 1'1 I'd ,.. III IE! "!; .., I'! N .,.,
GRAIN SIZE IN MILLIMeTERS
CLASS If ICATION
Dark gray, -slightly silty, clayey fine
to ("'Oarse SAND, with shell fragments
throughout
8 8 ~ N •
v:~ ~
NAT.
W.e. "
17
e Dark gray 1 slightly clayey, silty 16
to (.'Oarse SAND, wi thtrace of fine gravel
~
'Ii' q
LL
HYDROMETER ANAL '(SIS
~
1'1 q
I"L
GRAIN SiZE 11'1 lIIIiI/i
N q & ~ ~ S ~ ;; ~ q ~ q q
I)
10
20
30 l-:x:
!f!
ILl
40 s:
>-!II.l
II:
50 w
(f)
a: «
60 8
I-
Z w u
II: 10 w a..
-~. 80
. £"""-
N q
PI
90
100
~~ ~ ~ g N ...
10 ~ q q q
Stone £" Webster Engr. Corp.
Bradley Lake Project
GRAIN SiZE DISTRIBUTION
Doring SW 83-3
Sept. 1983
SHANNON 3< WIUON. INC~
G Ciot\llchnh:al COI1\!!ultl!lnts
K-0631
.11
25 ! . . . :"': . . . . i . ': .. :.... . . . . . I' . . . . . : . . . I' . . . . . . . . . I . . . . . . . . . I
j·········l········· ......... ·········1·········1 ; ......... I ......... i ......... I ......... j •.•....•• i !·········I··'················· ·········,·········1 j:::::::::j::::::::: ::::::::: :::::::::1:::::::::1
I:::::::::,:::::::::.::::::::: :::::::::I:::::::::!
, ••••••••• j ••••••••• j ••••••••• j •••••••.• , ••••••••• !
20 i-; I I · _.. l' ! ......... j .......................•.... j ..... , .. .
'@ 1:::::::::1::::::'·: :::::::: :::::::::,:::::::::f
0. I::::::::: I::::: <::: :'\::::::: I::::::'::!::::::::: I ~ {< .... "" ...... 'I"""' ..•.... :a,"o~.". o ... o .... : ...... ~.~*:
tr.l i .... < • • •• ••• • •••• I •. • ••••• ! .... " .. , j ..•.... , . 1
~ I ......... I ......... I . . . . . . . .. .... . ... ! ......... I
~ r~ ; ;.~ : : : ; ; ! : : : ; ; ;': : : . : ; : : ; : ~ :: ;::;: ~-.; : ; I ;.; -; : ; .: : ; ; I
~ , ••••••••• 1 •••••••••••••••••••••••••• ! ......... j ~ 1:::::::::1·::::::::1:::'·:::: :::::::::1:::::::::1 , .................. ! ........ ·········1·········, ! .................................... ! ......... \
1::::::::·j:::::::::I·::::::::!:::::::::I:::::::::j
10 I :. :-.. ".--.-.~ I::::::: :1:::::::::1::::::::: :::::::::1:::::::::1
I . . . . . . . .. ......... ......... ......... I . . . . . . . . . I ::::::.:: ::::::::: ::::::::: ::·:::::::j:::::::::l ........ , .......................... \ ......... ,
. . . .. ... . ....... ......... ......... I . . . . . . . . . .
I···· "'j .•••• ··r·········l·········!·········! 5 . '. --+. ; ~----.---; , : : : : . : : : . I! : : : : : : : : : i : : : : : : : :: ::::::::: I : : : : : : : : : I
! ... '" . ·········1········· ......... ! ......... ! ! : : : . .. . : : I' : : ; : : : : : : I : : : : : : : :: :::::::::!::::::::: i
i· .................!......... ......... .........! I •. • •.•• ••••••••• I . . . . . . . . '1' . . . . . . . . I . . . . . . . . . ,
j',:::::::!:::::::::I::::::::: :::::::::1:::::::::1
o ·sL._"· 10 15 ·-2t-----.. ···-~
Bori ng 514 83-3
Sample &-2: 4.5-5.0 feet
@ Undisturbed. Sample
Dry unit Weight :::: 110 :pcf
water Content :: 24%
o Renolded Sample
Dry Unit weight := 109 :pcf
water Content :: 21%
u'NIT STRAIN F %
Stone & Webster Engr. Corp 0
Bradley Lake Project
UNCONFINED COMPRESSION TEST
Boring SW 83-3
G fiotllu:nniclll Consu Ital'lls FIG. 12
25 1_ . . . -, . . . I . . --. . . . . I . :' . . . . . . . i . . . . . . . . . i . . . . < • • • • I
." •••••• ! •••••••• ,j •..•..... ! •..•..••. j .•••••••• !
. . . . . . . . . . i . . . . . . . .. ......... i . . . . . . . . . , . . . . . . . . . ! 1·········1········· ......... ! ......... j ......... j
I:::::::::,::::::::: ::::::::: :::::::::I:::::::::j ........................... 1 ......... 1 ••••••••• 1
I·········j·········,········· ·········1····· ... j
t ......... i ......... I . . . . . . . .. . ........ ! ....... "' .. j
20 Ii' i 'i
.. ~.~.,.~e.! •• 4-""'.o"~ ~ .... ., ....... "' .... ., .... i.~ ... ~~"".! 'i •.••...•.. I . . . . . . . .. ......... . .. , ..... ! ....... ,.!
! • . • • • . . • . ! • . . • . . . •. ••••.••.• .••...•..•......... I I . . . . . . . . . I • • • • • • • •• ••••••••• •••••• • • • • • • • • • ! ......... ', ........................ ! ......... !.
j
......................... ,. , ...... ! ........ . til ....... ,.j ......... ! ....... ·I·········!·········j
~ ,:::::::::1:::::::::1:::':·:::1:::::::::1:::::::::1 ~ 15 . , . I ! _~_--;
til Ii::::::::: ... ., ............ :::::::::\':::::::::1
E-i • • • • • • • • • • • • • • • • •• ••••••••• .........!
H • • • • • • • • . • • • • • • • •• ••••••••• .••..• .•. , ~ . . . . . . . .. ..... ... ......... . ........ i . . . ...... !
.••.•••....••..••••••.•.•. , ••.••.•.• I ....... ,.!
~ .. '" .. " .... ~ ~ .. " .... ,," '" "," c-.. ., '" .. &" .. " c' .... ,. ...... i .. ., ... Q ~ ... " . I . i
10 . : : : : : : : : : I : : .. : : : : : I : : : : : : : : : I : : : : : : : : : I : ' : : : : : : : I
. . . . . . . .. .•....... I . ., -. .-. '~-:l
::::::::: ........ ::::::::: :::::::::1:::::::::1 . . . . . . . .. ......... ......... .........!....,..., I , . . . . . . .. ......... ...................!
:::::::':1::::::::: ::::::':·1:::::::::1
........ :::::::::1::::::::: ·::·:::::j:::::::::1
5 .. . -t-------.. -... .........,
1:::::'.::1:::::::::.::': .. :::1:::::::::1:::::::::1
, •..••.•.. j ...••....••••••.•• ! ......... ! ......... i
0: 0" ,,, ... ~ ~ .... cl· .. "·c., .................. · .. ·"'iO"·"' .. ·I"'·· .. · .. ~··i
• .. ...... ..•...... ........• .•..•..•. I . . . . , . . . . i
: : : : : : : : : . . : . : : : : :: ::::::::: II : : : : : : : : : f : : : : : : : : : I
. ..j ............................ ! ......... ! o 5 10 15 20 .-.. -... -......... ~
Boring SW 83-3 UNIT STRAm f %
Sample S-2: 5.0-5.5 feet
• Undisturbed. Sample
Dry Unit ~1eight "" 106 IJ=f
Water Content = 24%
o R6rolded Sample
Dry unit Weight == 104 pef
Water Content :;;; 24%
NOI'E: Unconsolidated -undrained Test stone & Webster Engr. Corp.
Bradley Lake Project
TRIAXIAL mMPRESSION TEST
Boring SW 83-3
Sept. 1983
SHANNON & WILSON. INC.
GsotGchniczl CO!'lsuitanu
K-0631
fiG. 13
25 T . • • • • • • .', I . . . . . . . ,. .,....... I . . • . . . . . . : . -. . . . .
! ••••....• j •••••••••••••••••• j ••••••••.•••....
! . • . . . . • • • . i . . . . . . . .. ........ . '1·:·::.·.·:.·.·:.:.:.1:.: .. ::.·.·:.·.··.·: .......................... .
~ v 0;:.., ...... " .. '" ""'., ....... " ........ ~~ •••
'1:::::::::1::::::::: ::::::::: ::::::::: :::::::::
... " .... .., ................ "' ....... "' ....... 0<1 ....... "'''' ..... ~._ ••
20 I . . . . . . . . . I . . . . . . . . . I . . . . . . . . . r . . . . . . . . . I . : . :.: .. · .... m:.
I : : . : : : : :.: :::::::::'::::::::: ::::::::: :::::.::: I .. : .. '"¢~ •• ""'& ........•• "., ... ~ ....... ., ••••• ~ ....... ,-
'M I : : : : : : : : : I : : : : : : : :: ::::'::::: f' : : : : : : :: : , : : :: : : : ' : a ' .. " ~ !> ...... .,.. jj G ......... ., " S .. " • ., ...... ,,' ................ ! ... .
1:::::::::1:::::::::1:::::::::1:::::::::1:::': :
~ 15 t-:-, ..•.. , .. _,i , ....... '1' ......... ; ... " ...... r~~-" :m. : . . , . ! ~ I :: : : :: : : : I : : : : : : : :: ::::::::: ::::::::: -~ : : : . : : : I I .. "" .. ., .. .. .. .... ...~., .... ., C \I <I ~ (I \I .... " ., .... ' ,,<I............ ...... ~ . . . . . ~
E-I , ••••••••• ,......... ••••• ., ••••••••••••••...• ,
li i : : : : : : : : : ! : : : : : : : : : I : : • : . : : : : . : : : : : : : : : I : : : : : : : : : I
o I··········,·········!········· ................. [ 10 "'-' ... 1
I· . . . . . . .. ........ . . . . . . . . '\ . . . . . . . .. ......... i
(;tl ..... ~ ••••••• "' .. ~., .. 00 ..... "., ..... 0 ..... " ,., ... ~ ••••. ~
......... "' ....... " .. "' ...... ., ......... " •• e ... ,,~ ..... ~"~ •••• ~ :::::::::1::'::::::: ::::::::: ::::::::: :::::::::1
5 I : : : : : : : : ~ I : : : : : : :: : I : : : : : : : : : I : : : : : : : :: :::~: 1 I . . . . . . . . . . . . . . . . . . . I . . . . . . . , .' . ...... I . . . .. ... 1
I : : : : : : : . : ,i : : . : : : : :: :::":..: I : : : : : : : : : ! : : : : : : : : : ! I······ .................. ··'······I·········~ I : : : :: ::: I : : : . : . : : . I : : : : : : : : : ~t : : : : : : : : : I : : : : : :, : : : I
I:"::"': : ... ::::: I::::::::: _:::::::::.::::::::: i
o ---s--' 10 1 20 ....... "H"15
Bori ng SVd 83 .. 3 UNIT STRAIN I' %
Sarcple 5=4: 12~O-1205 feet
Undisturbed Sample
Dry Unit Weight =: 107 pcf
Water content = 22%
o p~lded' Sample
Dry unit Weight "" 103 pcf
Water content == 23 %
NarE: Unconsolidated. -Undrained Test Stone & Webster Engr. COr:?
Bradley Lake Project
'I'RI.AX"'JAL CCl>1PRESSION TEST
Boring SW 83-3
Se . 1983 K-0631
Geotlllchnical COflsulUnts FIG. 14
25 I I ' i A, ~, I········· ·········!·········j·········j·········i
I ~ : ~ ~ ~ ~ ~ ~ ~ I ~ ~ ; ; ~ ; ~ ~ ~ I ~ ~ ~ ~ ~ ~ ; : :1 ~ ~ ~ ~ ~ ~ ~ ~ ; I ~ ~ ~ ~ ; ; ~ ~ ~ I
j ·········!·········I·········I·········!·········! "1V"' ..... ~ .. e .... ".~Q ... ~,." ........ _~ .. ~"~.~., .. ,."t ..... O ••••• i I········· ·········1········· ......... 1 ......... : !·········j·········j·········i·········j·········!
20 I . . :~. . . . . . I . . . . . . . . . ! . . . . . . . . . ! . . . . . . . . . i . . :-:-.~-:_.: ... :m: .. 1
j···········I·········j·········I·········I·········: , ........................... j •.•.••.•• ! ......... l
! . . . • . . • . . I . . . . . . . . . I . . . . . . . . . ! . . . . . . . . . i . . . . . . .. ;
lsi.!.:: : : : : . : I : : : : : :: . : I : : : : : : : : : I : : : : : : : : : I : : :/ : i I .... · .... I· ........ I ...... ·· ., ........ ·1· .. ····;
I:~::::::: i::::::::: I::::::::: i::::::':: I::::::::: ~
l ·······,·!···················!·········!··········i I:::::::::,:::::::::I:::::':::!:::::::::I:::::::::[
1Ot:::::::::1:: ;.::::: :1::::::::: i::::::::: 1:: :.:--: >-:·1 I::::::::: ::::::::: I::::::::: I::::::::: I::::::::: 1
,·········!·········I·········!·········,·········j i: : : : : : : : : I : : : : : : : : : I : : : : : : : : : I : : : : : : : : : i : : : : : : : : : !
j·········.·········j·········l·········!········,1
5 1 •·••·••·•I ····.·····!·········j·········I·········i r::::: : : : i : .. : . : : . . . i : :: : : : : : : i : : : : :.: ::':l : : : : :":"':":"':"1
I : : : : : : : . : !' . : : : : : : : : I : : : : : : : : : I . . , . , : : : : i . : : : : : : : : I ! . . . . .,., . . . . . . . . . . , . . . . i . . . . . . . . . I . . , . , . . . . 1
I : : : : : : : : : ! : : : : :.: : : : I : : : : : : : : :j : : : : : : : Ul : : : : .ULJ
o 10 15 20 2S
Boring SW 83-3 UNIT STRAIN F %
Sample S-7~ 22.9 -23.6 feet
" Undisturbed Sample
Dry Unit weight = 103 pef
Water COntent = 21%
o Remolded Sample
Dry Unit weight == 101 pc£
Water Content == 24%
NOTE: Unconsolidated -Undrained Test
stone & Nebster Engr. Corp.
Bradley Lake Project
TRIAXIAL Caof:PRESSION TEST
Boring SlrJ 83-3
Seot. 1983
SHANNON 8. WilSON, INC.
Geotechnical ConsultsnU
K-0631
F!G. 15
Boring
1. S'W 83-2
2. S'W 83-3
3. SW 83-3
4. SW 83~3
5. SW 83-3A
6. biN 83-3A
(I)
~
w "'U
'" ~ •• .u r-
: ; tJ:) l>
... '"" 00 ~ U) "'z w "z I-' 4 "'c ~ H !:: n ~IO" i !-S ,..."" -I
n ..... -< <>011'>
"'0 n "'2 c. 8 ... :l: .. -J!» .. z
""n LJ. AJ ..... a -I ...
~
!
1 0
0'1 i w ) I-'
DE:pth (f1:.) 10 ~----------------"'"'II"-----------------"""
159.0
4.7
12.2
23.2 60
1.7
8.5
50
(I)
i
II'>
~ ~ 10
ell
~
E 0 b" 0 re
Ii ~"
I.Q
e .a
1
I
C~fU
10 20
eli
Cl
6 0" II Mit ~ 2 •
rill & Ol
30 40 50 60 70 86 90 100
UQUHI UMn
-+J
Q)
OJ
4-l
:I:
E-;
,:l,
£i;.'!
0
o
SHEAR STRENGTH
(tsf)
0.5
SENSITIVITY
RATIO
1.0 a
WJl.TER CONTENT
(% )
20
LIQUIDITY
INDEX
40
o --+ I --J i ......... I ......... I l ~ .. ----~ I : : : : : : : : : I : : : : : : : : : !
5
10
15
20
25
! : : : : : : : : : i : : : : : : : : : i .!I:~~~:~:II:::::::::i~ 3.6
.l:'Jr& .......•• , ••••••••• i -2. 7
I::::::::! :::::::::1 (f\ i· ..... &, •• I ·o...:m·· ... ! ___ 1.~
i . . .. 7":"':-.--: -: ..•••• ! -2. 7
I : : : : : : : :: : :~: : : : :", . I
i ........ · ........ (2.3)/8.6
! . • • . 0----- - - -.. ----te -1 ! . , .6-._ ......... .., .&," •••••• ! -.....
I, .. ~------6-······ 1-~ i .. ~ ... ".,~,. t<" .. ",.,,~.~l o..t...
i ~ '" . 4> ~ .. .. ~ -........., '" ~ ~ ~ -1 4 , "
I : :0..;';" ;..,:~..;~ ';';";";0 : : : : 1-
L ~::: ;~~l; I ~ ~ ~ ~ ~ ~ ~;; I-
I . . . . . , . .. ........, i i . . . . . . . .. ......... i ! . . . . . . . .. ......... I
i . . . . . . . . . I . . . . . . . . . I I . . . . . . . . . ! • . . . , • • . .
, . . . . , . . . . ! . . , . . , . . . I
I : : : : : : : : : I : : : : : : : : : I
I: . . .. .. " '> ~ ., .. ; .. .. .. • ,,.. f .. ~ ! ... , .... '1' .. , ..... I , . . . . . . . . . . . . . . . . . . ! ! . , . . . . . . . -. . . , . . . . . I
1:::::::::1:::::::::1 I . . . . . . . .. ....,....!
! ' . . . . . . . . I . . . . , . . . . i i ... , ..... I ......... !
j··(j.@·····!··········i-, ......... ! ......... ! ! . . . . . . . . . ! . . . . . . . . , i I ... ·9 .... ! ......... j
5.2
2.6
1.5
! ...... --'J T' '''l'''j
I" : " ..: : " "ii: : " { I
I·········i·~······i
,:":::::: :I""~ ::::"1
! •..•••.• ~ .•..•.. , ! . . . . . . . -. ! -. . . .. .. 1
1-····· _ .. i -0-···· --!
! •.•
I : : " : " : " : : H< : : : : I
! . . • • • • . . . I . . . . . . . . . l , .......• ! ......... !
I : : : : : : : : : ! : : : : : : : : : I , . .
I : : : : : : : : : i : : : : : : : : : i i . . . . . . . . . ! . . . . . . . . . !
1:::::::::1:::::::::1
1,········j·········1
i I' , i . . . . . . . " ..,.......
i:::::::::i:::::::::l i ~ . . 9 " .. ,. .. " j ~ h .. • a .. .. " • I
I . . . . . . . . . i . . . . . . . . . i i ......... le'-i ...... -i
i : : : : : : : : : i : : : : : : : : : l I . . . . . . . . . , . . . . . . . . . j
0.7
0.5
0.9
1.7
3. {j)
'FI' . . . . . . . . . I . . . . . . . . . i .••••••• I ••••• -••• 1 ! ......... I ......•.. i
: I 4 I : :~~:~~i: I : : : : : : : : : I-i ...... 'iV" ••••••••• i
i . . . . . . . . . t . . . . . . . . . !
:1' : : : : : : : : : I : : : : : : : : : I
: : : : : : : : : I : : : : : : : : : i 30 _i i .J
Lab Torvane
Field Torvane
Field Vane
Compo
Remolded Natural
&------~
" 0------•
0-----.... -.
Unconf. Comp. 0-.... --.... --Ill
CD Remolded test at 3% lower
water content than natural.
CD Average of 2 tests paral 1 to
sample and 2 tests perpendicular
to sample.
/::!:: i::: I::::" i:::1
I • • • • • • • • • I . . . . " , . . . 1
i... : :
Plastic Limit
~ ! II
/' Water Content
I
'Liquid Lirni t
Stone & v-!ebster Engineering Corp.
st.IMMARY OF TEST RESULTS
Geoteehnielll Consultllnts
K-0631
APPENDIX A
ANNOTATED REFERENCE LI
Clark, S0 He B.$ 1973~ The McHugh Complex of South-Central Alaska:
U@S. Geological Survey Bulletin 1372-D~
A brief description of regional lithologic units within the McHugh
Complex is presentedo It is of limited value to this study.
Cowan~ D@ S. and R. F* Bosss 1978, Tectonic Framework of the South-
western Kenai Peninsula, Alaska: Geological Soci of America Bulle-
tin, Volume 89, p. 15 158.
This paper presents a regional tectonic framework for the lithologic
and structural units in t project area.
00w1 Engineers~ 1983~ Bradley lake Project Geologic Mapping Program:
unpublished report to U.S. Army Corps of Engineers, Alaska District.
This is the most recent rapo on geologic mapping of proposed tunnel
alignment, quarry~ damsite, and powerhouse. Provides
damsite and powerhouse locations corresponding to pres
descriptions of lithologiC and structural map units~
ologic maps of
SWEC layout,
statistical
jOint studies for areas of
tal s.
ent powerhouse, exit and intake por-
K-0631-61
Soward, K. S~, 1962, Geology of Waterpower Sites on the Bradl River,
Kenai Peninsula, Alaska: U.Ss 010g1c Survey Bulletin l031-C.
This is the first reconnaissance ologic study of the Bradley Lake
project area. It provides general geologic descriptions and a map of
lithologic and structural featureso
UeS& Army Corps of Engineers, 1982, Bradley Lake Hydroelectric Project
General Design Memorandum No.2, Volumes 1 and 2, Alaska District&
This is a summary of most of the work done on the Bradley Lake project
to date. Its most significant contribution to this study is boring
logs fr~~ holes drilled in the vicinity of the present SWEC layout of
project facilities.
Woodward-Clyde Consultants, 1979, Reconnaissance Geology, Bradley Lake
Hydroelectric Project: unp~blished report to U3SS Army Corps of Engi-
neers, Alaska District.
Results of this study are incorporated, in less detail t in the "Gen-
eral Design Memorandum No. 211. This report presents a general geo~
logic map of part of the present study area~ and a useful delineation
and discussion of faults and lineaments~ It also provides descrip~
tions of lithologic units and rockmass characteristics, as well as
results from seismic refraction surveys in the damsite vic;nity~
Woodward-Clyde Consultants, 1981, Report on the Bradley Lake
Hydroelectric Project Design Earthquake Study: unpub 1 i shed report to
the U.S. Army Corps of Engineers~ Alaska District.
Resul of this study are incorporated~ in less detail, in the IIGeneral
Design Memorandum No. 2.11 This report discusses the evaluation of
des; gn earthquakes and the deri vat; on of desi gn ground mati on for the
project. It contains the calculation of seismic exposure, and discusses
the likelihood of on-site fault rupture. Methodo1ogy used is detailed
in two appendices.
APPENDIX B
GLOSSARY OF TERMINOLOGY
FOR
CATACLASTIC ROCKS
Cataclasis: The process by which rocks are broken and granu1ated due to
stress and movement during faulting; granul ion or comminution.
Cataclastic Rock: A general term for any rock produced by cataclasis,
regardless of whether or not the rock is coherent.
Compositional Layering: Layering due to chemical and mineralogical
differences <in the adjacent layers, regardless of origin. May
include color lamination.
Fault Breccia: A rock composed of angular to rounded fragments s formed
by crushing or grinding along a fault. Most fragments are large
enough to be vis"ible to the naked eye, and they rna up more than
30 percent of the rock. Coherence, if present, is due to secondary
processes.
Fault Gouge: Pastel ike rock material formed by crushing and grinding
along a fault. Most individual fragments are too small to be
visible to the naked eye, and fragments larger than the average
groundmass grains make up less than 30 percent of the rock.
Coherence~ if present, is due to secondary processes.
Fault Zone: As opposed to a fault which is by definition a plane of
movement, a fault zone is a zone of faulting. A fault zone may
consist of many separate fault planes concentrated in a relatively
narrow zone or may be a zone of distributed movements with few or
no distinct fault planes.
"
Fluxion Structure (fluxion texture): Cataclastically produced
directed penetrative texture or structure commonly involving a
family or set of S~surfaces; cataclastic foliation. May be visible
megascopically or only microscopically. Does not necessarily
involve compositional layering or lamination~ although many
examples do show such layering.
Foliation: Any type of recognizable S~surfaces of metamorphic (includes
coherent cataclasis) origin.
t4yl oni te: 11. coherent mi croscopic pressure-breccia vii th uxi on
structure which may be megascopic or visible only in thin section
and with porphyroclasts generally larger than 0.2 mm. These
porphyroclasts make up about 10 to 50 percent of the rock.
Mylonites generally show recrystallization even new mineral
formation (neomineralization) to a limited degree, but the dominant
texture is catacla ic.
A relatively large fragment of a crys 1, mineral gra;n~
or aggregate of crystals or grains, in a cataclastic rock.
Porphyroclasts are not produced by neomineralization or
recrystallization (as opposed to porphyroblasts). but may be
recrystallized in blastomylonites and mylonite gneisses.
Protom~lon;te: A coherent crush-breccia composed of megascopical1y
vlsible fragments which are generally lenticular and are separated
by megascopic gliding surfaces filled with finely ground material.
The fragments~ or "megaporphyroclasts 3 " make up more than about 50
percent of the rock. Protomylonite commonly resembles conglomerate
or arkose on weathered surfaces. Features of the original rock~
such as stratification and schistosity ~ may be preserved in the
larger fragments.
S-Surface: Any kind of penetrative planar structure in rocks.
Shear Zone: A zone of shearing in rocks; essentially like a fault zone~
but more specific because it excludes zones of faulting not
associated with shear. See fault zone.
Structure: The mutual relationships in space (geometric configuration)
of various components of a rock (crystals, parts of crystals,
multigranular aggregates, or microscopically irresolvable
groundmass materials), and any character; ic features to which the
arrangement of these parts gives rise. Europeans have
traditi ana lly used texture for what Ameri cans ca 11 structure, and
vice versa. Here~ following Turner and Vernoogen (1960), the two
terms are considered interchangeable when applied to metamorphic
rocks.
Ul tram~l onite: A coherent, aphaniti c, ultracrlJshed pressure brecei a
wlth fluxion structure, in which most of the porphyroclasts have
been reduced to breccia streaks and the few remaining
porphyroclasts are smaller than 0.2 mm. These porphyroclasts make
up less than about 10 percent of the rock. As in protomyloni and
mylonite, recrystallization-neomineralization is present but is
subordinate to cataclastic texture. In hand specimen and outcrop,
ultramylonites are commonly homogeneous-appearing rocks (although
many have compositional layering), easily confused with chert,
quartzite, or felsic volcanic rock. Ultramylonite represents the
highest stage in intensity of mylonitization in the series
protomylonite-mylonite-ultramylonite.
From: M.W. Higgins, IiCataclastic Rocks ll
, U.S.G.S. Professional Paper
687.
maro 1
SW 83-1 Box 9
Intake structw.."e
Massive graywacke fran this zone contains local
zones of fluxion structure with foliated argil-
lite.
" ;
, :.,.\
i I """_"_)r..~"I._1\I __ "'l!":':w.:')'l~~''!1.''''·'' c· v''', ",~,'''W'''""""'''',,,q,,,,,
I .","
PHaro 2
SW 83-2 Box 28
Bradley River Fault Zone
Contacts between foliated argillite (black
material) and. massive graywacke (gray I!Iaterial)
are shCl'ilm in this core :box, as well as S!lIall
zones of cherty argillite (upper left) and.
mixed. graywacke and argillite (upper right).
1be white veins are calcite. ,
... %!
PHaro 3
SW 83-2 Box 15
Bradley River Zone
Fault gouge and breccia are sha.m here with
fragments of chert and cherty argillite.
PHaro 4
SW 83-2 Box 7
Bradley River Fault Zone
The cherty argillite typically encountered
Boring SW 83-2 is shown here.
I
I ! .
PHOTO 5
SW 83-4 Box 22
Bull Moose fault 'Zone
Fluxion structure is wen displayed, in this
zone of chert with stringers of argillite,
PHOIO 6
SW 83-4 Box 5
Bull Moose Fault Zone
Tectonically mixed argillite and graywacke are
shown here with porphyroclasts of chert (light
gray material). The small zone of chert fran
about 36-37 Q 2 feet (third rCki1, right) is rela~
tively "pure" canpared to che:rt zones that were
typically encountered.
PHOTO 7
Boring SW 83-1
I Structure S1
This photo looks approximately east at Bradley
A north-northeast trending lineament,
accentuated by a brushed trail, parallels the
rock at the right of the photo.
PHOIO 8
Boring b'W
Bradley Ri ver ~"iaul t
''-''-''In. ... u.~ appr01d:mately south fran the
location of Borill9' SW 83-2, the arrCJ.f1S on
the left right in photo show' the east
and west traces of the Bradley River Fault,
respectively. t:wo traces converge very
near'lflhere the boring was drilled.
PHaro 9
Boring SW 83-4
Bull MOose Fault
Viewed fran the North, the main "1-... ,'''''''
the Bull MJose Fault is quite
rig is shown on boring location in
of proto.
PHOID 10
Boring SW 83-3
Barge Basin
Sheep Point. is shown at the right
photo 9 which. looks south at the east
Kachanak Bay $ 'Ihe ooring location
by the arrow 0
PHOl'O 11
Test pit
Powerhouse
ShallCM bedrock was confi~ in this
hand-dug test pit.