HomeMy WebLinkAboutSoils-Foundation Investigation for Poer Lion Hydroelectric Project 1980KOD-P
005 Alaska Po we r Authority
LIBRARY COPY
SOILS-FOUNDATION INVESTIGATION
FOR
PORT LIONS HYDROELECTRIC PROJECT
PREPARED FOR
KODIAK ELECTRIC ASSOCIATION} INC.
AND
ROLAND A. JONES -CONSULTING ENGINEER
PREPARED BY
HOWARD GREY & ASSOCIATES} INC.
GEOLOGISTS & ENGINEERS
ANCHORAGE} ALASKA
OcTOBER} 1980
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SOILS-FOUNDATION INVESTIGATI
FOR
PORT LI HYDROELECTRIC PROJECT
PREPARED FOR
KODIAK ELECTRIC ASSOCIATION) INC.
JU~D
ROLAND A. JONES -CONSULTING ENGHlEER
PREPARED Bv
HOWARD GREY & ASSOCIATES) INC.
GEOLOGISTS & ENGINEERS
ANCHORAGE) ALASKA
OcTOBER) 1930
INTRODUCTION
~-~----
Field examinations were conducted during the summer months of
1980 in the vicinity of Port Lions, Alaska to ther geologic
information pertinent to the design and construction of the
proposed hydroelectric project.
Port Lions is located in the northern portion of Kodiak Island,
about 30 miles west of the City of Kodiak.
The hydroelectric facility will consist of a storage reservoir,
located about 3 miles west of the city and the main facility
damming the Port Lions River adjacent to the townsite. Water,
with a head of some 90 feet, will be delivered to the power
generation station via penstock.
The on-site investigation examined both surficial and bedrock
deposits to determine their applicability to the project.
The contents of this report contain the results of the examinations
at both sites. Also included is an evaluation of building materials
within close proximity to the selected sites.
Locations at both damsites are depicted on the vicinity map.
(Figure A)
FIELD ITETHODS
The field work at Kodiak \vas performed in three phases. An
ini 1 reconnaissance trip was conducted to obtain general
information on both sites. This luded identi ing general
surface features, mapping bedrock exposures and hand excavation
of test pits.
The second phase consisted of drill a series of holes along
the dam axis. The drilling machine was a Mobil-}1inute Man drill
equiped with ~·' solid flight augers combined wi a 2" split
spoon sampler and a 70 pound hammer. The split spoon equipment
was used to obtain samples and penetration resistance values of
the underlying material.
A total of 15 holes at 6 separate locations were drilled Along
the Cresent Lake dam axis. In all cases, the holes were abandoned
due to refusal on lar8e rocks. Generally, the holes were drilled
to about 7 feet, but in no case did any of the bor s reach
bedrock.
Due to the dense nature of the subsurface materials, the drilling
machinery was not transported to the Forebay darn site. A series
of four hand du~ test pits were excavated along the axis of
lower dam. Two of ese holes did reach bedrock, while the two
holes thest from the river did not.
- 2 -
Percolation tests \•Jere also performed at both the upper and
loHer sites.
The f 1 phase of this investigat utilized a Bison Model
1570 C, s 1 enhancement seismograph, to determine the approx-
te thickness of the surficial deposits and the depth to bedrock.
Seismic lines were located along both dam sites as illustrated
in Figures No.l-1 and 2-1.
Seismic velocities and strata depths were determined and are
graphically displayed in Figures No.l-2 and 2-2.
As noted on these illustrations, the seismic velocities of similar
horizons vary. This is due to topographic variations, the thick
accumulation of volcanic ash and to an irregular bedrock surface.
Logs of all test ho s and borings as well as percolation results
are included with the report.
In general, both sites exhibit the same basic atures: a surface
layer of organics, organ silt and volcanic ash over a gravelly-
till material of various den
and graywacke bedrock surface.
which covers an irregular slate
- 3 -
LAB ANALYSIS
Samples of the dense glacial materials recovered during field
work were returned to Anchorage for laboratory analysis.
The analysis included particle size distribution, moisture contents
and Atterberg Limits.
Results of these tests indicate that the till material overlying
bedrock at both the upper and lower sites is a silty-sandy-
gravel.
A lateral moraine which sub parallels the Port Lions River along
the north side the vicinity of the Forebay Dam was also
analyzed. This material is a clayey-gravelly-sand.
Results of all laboratory analysis are included with this report.
PHYSICAL DESCRIPTION
The present surface topography of the subject area is a result
of Pleistocene glaciation, being modified by present erosional
forces. Evidence of this is characterized by the glacially
sculptured ridges and cirques of the surrounding mountains.
Glaciers apparently occuppied the wide valley west of Port Lions,
originating in the higher mountains and flowing toward the sea.
- 4 -
As the glaciers advanced they scoured the bedrock and upon re-
treat deposited various amounts of glacial till on the vall
floors. The till is a dense accumulation of unsorted silt,
sand and rock particles up to boulder size. The particles
are generally sub-rounded to sub-angular and consist of slates,
gray\·mckes and granites.
The present hummocky surface with numerous ponds and small lakes
is a typical product of glacial activity. Cresent Lake is the
result of glacial scour and pending behind moraines.
Since the last glacial retreat, an organic silt of about 2 feet or
less in thickness developed over the glacial drift. In June, 1912,
the erruption of Mt. Novarupta blanketed the area with volcanic
ash. The ash grades from a fine angular sand to a silt. The
present ash accumulation varies between ridges and intervening
valleys but is generally about l~ feet thick.
Drainage in the area is poorly integrated, with numerous streams
draining small areas.
t.Ja ter from Cresent Lake flows for some 3 miles to the East,
through lakes and marshes and meandering streams before joining
with two southward flowing streams to form the Port Lions River.
The topography of the area between Cresent Lake and the village
- 5 -
of Port Lions, which is characterized by nurrerous nonds and
marshes, is typical of terrain developed on a slacial ~~round
moraine.
GEOLOGY
Geologically, Kodiak Island is an extension of the Kenai
mountains. Bedrock throu8h this portion of Kodiak Island is
composed of Cretaceous slates, graywackes and argillites.
Kodiak Island is separated by two major fault systems, into
three areas characterized by different types of sedimentary rocks.
The eastern portion of the island contains Tertiary marine and
continental sediments. The western part is characterized by late
Triassic to early Jurassic volcanic and sedimentary rocks.
Sediments of the central section, which cover the majo ty of the
Island, including the subject study area, are described as pre-
dominently Cretaceous slates, graywackes and argillites. (Hoare,
1967) Some minor amounts of conglomerate and tuff are associated
with these rocks, but none was evident at any of the outcroppings
stud d. The rocks are extensively folded and faulted. The
general geologic structure of Kodiak Island and vicinity is
illustrated on Figure B.
Bedrock in the Port Lions vicinity is a thin to moderately thick
bedded, brittle, dark gray to black slate. At the lower site
it trends north 35° -45° east, with a westerly dip of 15° -20°.
-6 -
Strata at the upper site trends northwest with a 20° -27° dJp
to the east.
The slates weather into platey sheets and generally no soft or
high ~~eathered rock was observed. The bedrock contains tight folds
and is fractured, with no apparent pattern.
Structure
Two major faults, both of which trend to the northeast, extend
across Kodiak Island. As previously mentioned, these faults
separate the major rock groups of the Island. (Figure B)
A normal fault displaces rocks on the eastern side of the Island,
while a thrust fault extends along the western coast.
Numerous other faults representing local stress adjustments have
been mapped in the central portion of the Island. (Moore, 1967)
Quaternary Deposits
Quaternary deposits consist of unconsolidated silt, sand and
gravel deposited as a ground moraine during Pleistocene and
Recent geologic time. This material covers extensive areas be-
tween mountain ridges, to depths from a few feet to 40 feet and
more.
A generalized map (Figure B) illustrates the surficial geology
of the study areas.
- 7 -
SI DESCRIPTION
Forebay Damsite
The lower facility, the Forebay Dam, will be constructed on the
Port Lions River, immediately south of the townsite.
The stream draining Cresent Lake together with two creeks flowing
from the mountains to the north, form the Port Lions River. West
of the damsite the stream is some 30 et wide and flows on a
gravel stream bed. At roughly the Forebay Dam site, the stream
is incised into the slate bedrock with steep, near vertical banks.
Downstream these walls approach 50 feet in height at some
locations.
Bedrock is well exposed along the lower portion of the Port Lions
River. The rock is a thin to medium thick bedded, dark gray
slate. It is well indurated and contains extensive tight lds
and fractures. The rock separates along bedding planes when
struck. Generally, the exposed rock showed little deterioration
due to weathering.
The strata trend N35° -40°E and dip to the west from 17° to 25°.
A plan view of the area is illustrated in Figure No.l-1. Figure
No. 1-2 represents a cross section along the dam axis based on our
test hole notes and geophysical surveys.
- 8 -
The surface bedrock apparently rises to the sou
dips and peaks.
with frequent
Overlying the basal slate unit is a till material similar to that
encountered in the Cresent Lake area. The 11 varies in thickness
from 0 to 30 et, and is composed of an unstratified mixture of
gravel, sand and silt. Analysis of this silty-gravelly sand is
included in the appendix. Covering the till is an old organic
silt overlain by volcanic ash and a recently developed organic
silt. The depth of material covering the till varies, but is
generally under 4 feet. Seventy-five et north of the Port
Lions River and running some 500 feet to the west, is a moraine
deposit of clayey-gravelly-sand. Results of analysis of this
material are presented in the appendix. The material is very
dense and a percolation test indicated an infiltration of 80
mintues per inch.
About 300 feet west of the damsite a large abandoned river meander,
covering some 5 acres, contains a substantial amount of clean
gravel with little soil cover. (Figure C) No test pits were dug
at this site due to lack of access, but a minimum 5 "foot layer of
gravel apparently is present. The gravel, mostly derived from
slate, graywacke and granite is well-graded with about 10% greater
than 3 inches. An estimated 40,000 cubic yards could be removed.
Other meanders with gravel deposits exist further upstream. All
are at greater depths and contain more fine material.
- 9 -
Cresenl Lake Damsite
Cresent Lake is located approximately 3 miles west of the village
of Port Lions. The lake is about l mile long and %mile wide.
The lake is at an elevation of about 300 feet and lies in a large
broad east-west trending valley, flanked by 1000 to 2000 foot
mountain ridges.
The proposed dam will raise the water level of the lake about
12 feet.
A plan map a~d cross section of the dam axis are illustrated in
Figures No.2-l and 2-2.
There are three bedrock exposures within the immediate damsite
areas. (Figure No. C) Two are located along the north edge of
Cresent Lake, on each side of the discharge stream at water level.
Bedrock at these outcropings trends northwest and dips .to the east.
About 500 feet east of the Cresent Lake shoreline, another outcrop
is exposed at a bend in the stream. Here similar rock strikes
to the northeast and dips to the east. The difference in trends
could be due to faulting, folding or the exposure may be a dis-
placed block which has shifted from its original position.
Another bedrock exposure is visible on a small, whale back shaped
island, east of Cresent Lake. No data was collected from this
island since there was no access.
-10 -
The bedrock is a thin to moderately thick dded dark gray slate.
The slates are well indurated and separated along bedding planes
when struck. They are only slightly weathered and exhibit ti~ht
folding and fracturine .
Figure . 2-1 is a plan view of the Cresent Lake area, all
locations of test holes, borings and seismic lines.
Figure No. 2-2 depicts the subsurface depths along the dam axis
as established by test holes and geophysical methods. As shown,
the uppermost layer is composed of oreanics, volcanic ash and
organic silt. This layer grades to a till comprised of silt and
silty-sandy-gravel., containing numerous large boulders. The
contactshown between the uppermost soils and the till material
is actually at depths corresponding to the boulder layer.
Bedrock depth across the axis varies between 15 and 40 feet. The
surface slopes upward at both the north and south ends. A pro-
nounced depression in the rock surface at point 25+00 along the
survey line may be an ancient stream cut. Although no change in
materials was noted, alluvial gravels might be present in the
lower portions of this deoression.
It is assumed that the Cresent Lake da~ will be of earth fill
construction. The till will be used for 11, compacted and keyed
into similar gravelly-material. The till analyzed is a silty-
-11 -
Eravelly-sand containing
gravel 43%, sand 4 and silt 12%. Percolation testing
in the upper 2 feet of the till showed in ltration rates of
between 20 and 26.7 minutes per inch.
RECOMMENDATIONS
General
Foundation conditions at both damsites include glacial till over
bedrock. At both sites, in some areas, the till has been eroded
away and rock is exposed at the surface.
Blanketing both sites are organic silts, volcanic ash and organics.
At the Forebay site, construction materials for an embankment
dam include sands and gravels from an abandoned river channel,
and a clayey-gravelly-sand, morainal deposit. At the Cresent Lake
site, silty-gravelly-sand and a glacial till is available for dam
construction. The surficial ash and organic rich soils would not
be suitable for dam construction or foundation materials.
Site Preparation
Due to the potentially unstable and compressible nature of the
surficial organics, volcanic ash and organic silts, these
rna terials should be removed from the foundation area. l.fuere the
dam will be founded on the hard slate bedrock, a keyway should be
cut into the rock surface. Such a key should slope downward,
going upstream. In addition, dependine upon the width of the
embankment, a slot at least ten feet wide may need to be cut into
-12 -
rock, to form a cutoff tren Once a configuration has been
tentatively selected, we should be allowed to evaluate s
potential and dam stability to provide for foundation sloping,
cutoff and embankment stability.
Where the dams are supported by the glacial till, a keyway may
still be required. It , however, not to extend to rock.
Filling
Earthfill darns should be constructed with compacted structural
fill. Typically, such fill is compacted to at least 90% or 95%
density based on AASHTO Standard: T-99. On Kodiak Island, due
to the generally rainy weather, the silty-soils available for dam
construction will probably become moistioned during grading. Once
they are moistined even slightly and become wetter than optimum,
they will become difficult or impossible to compact to the de-
sired degree. Thus, it may be necessary to design the dams with
less dense fill. This would, however, call for relatively flatter
sideslopes.
Another option for design may be to improve fill strength and
stability through the use of soil-cement. This approach has the
advantage of eliminating the need for riprap.
However, earthwork may be appreciably more difficult, especially
since large rocks would need to be removed from the fill. Also,
soil-cement construction reauires the use of extra machinery,
v7hich would,~eed to be transported to the remote sites. Finally,
soil-cement construction should be performed by a contractor
-13 -
familiar with the technique.
Outlet Works
Conduits which penetrate through the dans or their abutments can
be sources of leakage. In order to control such leakge, cutoff
collars or diaphrams around the lines will be necessary. S?ill-
ways and low level discharges should be aligned with the stream
channels, so that bank erosion does not become a problem.
Spillways will probably need soroe form of lining to control
erosion. Depending upon discharge ouantities and velocit s,
spillways may be lined with sod, gravel riprap or concrete.
Slopes
Commonly, embankment dams are designed with the sideslopes of
3H:IV to 5H:IV. Depending upon foundation conditions and em-
bankment materials, slopes as flat as lOH:IV may also be necessary.
Thus, once an embankment material type is selected and a 11
density is established. specific embankment slope angles can be
evaluated.
The face of the embankment exposed to the reserve should be
protected from wave erosion. This may be accomplished with rip-
rap, soil-cement or durable facing. The appropriate form of bank
protection should be based upon wave heieht, frequency and
embankment slope angles.
Monitoring
Prior to construction, permanent, groundwater elevation monitoring
-14 -
points should be installed downstream of the Cresent Lake damsite.
A minimum of one piezo~eter should be located in the swale about
150 feet southeast of the stream draining Cresent Lake. This well
should be located within 50 feet of the downstream toe of the dam.
It would also be prudent to install a second groundwater monitoring
well, in the swale about 200 feet south of the bend in the dam axis.
This well should be set on the order of 10 to 30 feet from the toe
of the dam.
These monitoring wells should be installed as soon as practical.
They should be read on a regular basis, prior to construction of
the dam, to establsih background data, against which operational
changes may be compared. These wells shn11Jd be monitored
continuously during the initial pool filling and thereafter until
any changes in the groundwater regime are established and under-
stood.
If during or shortly after pool filling, water levels begin to
rise appreciably, it may be necessary to install a network of
relief wells, construct a toe berm or improve dam stability or
to blanket portions of the reservoir with impervious materials,
to prevent a potential failure.
We appreciate having the opportunity to provide these initial
design recommendations. As plans develop, please do not hesitate
-15 -
to contact us for additional geotechnical data.
Respectfully submitted,
HmvARD GREY & ASSOCIATES, INC.
'b'' . ' .. ,,
--OF AL \\ --'~ ...•.•.. :cfs '' .,:''\.~·· *"·1-. ~-:' c.,... _. ·.y ,,
:J*;49TH . ".*f. ~...... ' ..... ·~
Howard J. Gr~ ,,..Erfglneering Geologist ~-. ••• • . •••••• ~
~~-. No. 1783-E -~~: / /// I~·. ~ Q :~~, t:_: ~/ I/ ? 11?i?:C?!,s,~~Y:<f·0~ df:<-_.; /(/-\ ~--\\\\'ONAL ~~--
-. \ ~""'"-"'-'"' Alvin R. Zeman, P.E. \
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LOG OF BORING NO. DH-1!1
DATE June 2 7 1980 . ' PROUECT Port Lions Hydroelectric
TYPE BORING Hand Dug Test Pit
LOCATION Cresent Lake, North of Stream
SURFACE ELEVATION
COMPLETION DEPTH 3 Ft.
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SOIL DESCRIPTION
Vegetation: high grasses and hrush.
0-4". organics and organic silt, dark brown,
very -soft, moist. (PT-OL) (F-4)
4"-14" volcanic ash, tan sandy-silt overlying
a white silty-sand, soft, moist.
14"-22" organic silt, dark brown,
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sand and gravels, some roots, IDHiljS. 7, I
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22"-36" sandy-silty gravel, dark brown, contains
cobbles and boulders, gravel and pebbles are
angular to sub-angular , cobbles and boulders
are mostly sub-rounded, particles primarily slate,
but does contain minor amounts of graywacke and
granites, moist, dense to very dense. Glacial
till.
(GM) (F-1)
36" further depth prevented by presence of large
boulders
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... o 10
HOWARD GREY a ASSOC. INC.
LOG OF BORING NO. DH4f2
PROUECT Port Lions Hydroelectric DATE June 27, 1980
TYPE BORING Hand Dug Test Pit SURFACE ELEVATION
LOCATION Cresent Lake, South Side of StrecQ>MPLETJON DEPTH 4% Ft.
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SOIL DESCRIPTION
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Vegetation: high grasses.
0-4" organics and organic silt, dark brovm,
very soft, moist. (ML-SM) (F-4) J
4"-10" volcanic ash, sandy-silt, tan to light .
brown, soft, moist. (ML-SM) (F-4) ~m
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10"-30" organic silt, dark brown, contains some
sand and gravel at base, roots, moist, firm. f\. (OL-SM) (F-4)
30"-54" sandy-silty-gravel, brown to gray with
depth, angular to sub-rounded gravels, sub-
round€d cobbles and boulders, mostly slate with
graywacke and granite, moist, dense to very dense.
Glacial till. (GM) (F-1)
54" digging stopped due to boulders covering
majority of hole.
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HOWARD GREY a ASSOC. INC.
LOG OF BORING NO. B-11
PROJECT Port Lions Hydroelectric DATE July 16, 1980
TYPE BORING Hand Dug Test Pit
LOCATION Forebay, Dam, 11+55' On Survey
SURFACE ELEVATION About 7 3 Ft.
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LineCOMPLETION DEPTH 3 l/3 Ft.
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SOIL DESCRIPTION
Vegetation: thick forest and moss covered ground.
0-2". organics and organic silt, composed of.moss
and thin covering of residual soil .
(PT-OL) (F-4)
2' -30" volcanic ash, sandy-silt .to silty-sand,
tan silt overlying white sand, some roots, moist,
soft .
(ML-SM) (F-4)
30"-40" organic silt, dark brown, contains some
sand and gravel, roots, moist, firm.
~ (OL-SM) (F-4)
40" bedrock, slate, black, fractured, easily
shattered, weathered, approximate strike -
N 30° E, southerly slope, water at bedrock
surface.
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HOWARD GREY a ASSOC. INC.
LOG OF BORING NO. B-12
PROUECT Port Lions Hydroelectric DATE July 17, 1980
TYPE BORING Hand Dug Test Pit SURFACE ELEVATION About 82 Ft
LOCATION Forebay Dam, 12+70' On Survey LineCOMPLETION DEPTH 4~ Ft.
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SOIL DESCRIPTION
Vegetation: thick forests and moss covered ground.
0-4" organic and organic silt, moss and decaying
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vegetation on thinly developed residual soil. I I I 1·
Soft, moist. (PT-OL) (F-4) .
4"-12" volcanic ash, sandy-silt to silty-sand,
tan silt overlying white sand, soft, moist. 1 1 1 1
(ML-SM) (F-4)
12"-24" organic silt, dark brown, with some sandv
and gravel, roots, moist, firm.
(OL-SH) (F-4)
24"-54" Sandy-silty-gravel; brown to gray with
depth, contains angular gravels, eontains about 5%
rounded to sub-rounded cobbles and boulders,
mostly slate with some graywacke and granite,
moist, dense to very dense. Glacial till.
(GM) (F-1)
54" bedrock, slate, black, fractured, flat
lying, hard, difficult to shatter, no visible
weathering, no strike or dip obtained.
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10 10
HOWARD GREY a ASSOC. INC.
LOG OF BORING NO. B-13
PROUECT Port Lions Hydroelectric
TYPE BORING Hand Dug Test Pit
LOCATION Forebay Dam, 13+30' On Survey
DATE July 18, 1980
SURFACE ELEVATION About 88
LineCOMPLETION DEPTH 5~ Ft.
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Vegetation: thick forests and moss covered ground.
0-4"' organics and organic silt, moss and decaying
vegetation over thinly developed residual soil, 1 1 1 I
soft, moist. (PT-OL) (F-4) ~
1--
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-
4"-12" volcanic ash, sandy-silt to silty-sand, · '
tan silt overlying white sand, moist, soft.
(ML-SM) (F-4)
12"-30" organic silt, dark brown to gray, with
sand and rocks to cobble size, sub-angular to
rounded, moist, firm. (OL-SM) (F-4)
30"-60" sandy-silty gravel, gray, contains angular
to sub-rounded gravel, pebbles, sub-rounded to
rounded cobbles and boulders, mostly slate with
some graywacke and granites, moist, dense to very
dense. Glacial till. (GM) (F-1)
No bedrock encountered. !5·
10 I I I I '10
HOWARD GREY a ASSOC. INC.
PROJECT Port Lions
TYPE BORING Hand
LOCATION Forebay
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LOG OF BORING NO. B-14
Hydroelectric
Dug Test Pit
·DATE July 27, 1980
SURFACE ELEVATION 85
Dam, 10+90' On Survey Lin&OMPLETION DEPTH 6 Ft.
(/') w* w O:::f-
SOIL DESCRIPTION
_J =>Z a.. t:;w ~ _f-<t oz CJ) ~s -
Vegetation: thick forest with moss covered ground.
0-3" organics and organic silt, moss covering
thinly developed residual soil. Soft, moist.
(PT-OL) (F-4)
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I I I
·,,·(· 3"-10" volcanic ash, sandy-silt, tan, sand and
1----f:'P.Y. silt mixture, roots, moist, soft.
0
/-
0 (OL-SM) (F-4) -o· . ~-/.~
.... ~ ..
~/o%' •• 0
·/.·I 0 . l--l,·<~i /' .I ~:·{:;/: "· . . 0 tl 0 ~----~·;.;:) . , ..
• • 0 ... 5 _j ::t:. ?' ,e/.•
/. !'/.
l--l,o/c,·
, •• 'I' .. ·/·.
f--
1---
10"-18" organic silt, dark brown, contains minor
amounts of sand and gravel, thin gray silt lense
at about 12" from surface, roots, very firm,
moist. (OL-SM) (F-4) J
18"-72" clayey-gravelly-sand, zray, angular gravel
and pebbles, rounded and sub-rounded cobbles and
boulders, mostly slate with some graywacke granite,
very dense, moist. Glacial moraine deposit .
(GM) (F-1) 5·
lB-H
1---
"'I() I()·
HOWARD GREY 8 ASSOC. INC.
LOG OF BORING NO. B-21
PROVECT Port Lions Hydroelectric DATE July 18, 1980
TYPE BORING 4" Auger SURFACE ELEVATION
LOCATION Cresent Lake, 2'+10' On Survey Lin~OMPLETION DEPTH 6% Ft.
t ..J~ z ot:t w
.. (f) !..2 ~
:X: aLL 0: 6: w (/') lJ... w lJ... (/')
a ~dl /
SOIL DESCRIPTION
Vegetation: low brush and grasses.
Organics and organic silt, dark brown, very soft,
moist. (PT-OL) (F-4)
Volcanic ash, sandy-silt to silty-sand, grades
downward from a tan silt to a white sand, soft; ·
(/') w~ w 0:1-1cr ::>z tf)W :!E -1-<{ oz (f) :!E8
1-= LL ..
:X:
ti: w a
moist. (ML-SM) F-4 1----1
~
~0-
1---
I---
!15
Organic silt, dark brown, contains some sands and ~ 5 gravel toward base, firm, moist to wet. -
(OL-SM) (F-4)
Sandy-silty-r,ravel, light brown to gray with
~ depth, cobbles and boulders, sub-angular to sub-J
rounded, gravels, mostly slate with some granites,
moist, dense .to very dense. Glacial till.
(GM) ( F-4)
Standard Penetration Test
1.4 split spoon and 70 lb. drop hammer
Depth Blow Count
3 I -3Jz I
3Jz 1
-3 3/4'
5% I -6 I
6 I -6% I
52
50
55
60
!'10·
115·
~OI I I I I 1~().
HOWARD GREY a ASSOC. INC.
LOG OF BORING NO. B-22
PROJECT Port Lions Hydroelectric
TYPE BORING 4" Auger
DATE July 18, 1980
SURFACE ELEVATION
Lin~OMPLETION DEPTH LOCATION Cresent Lake, 22+52' On Survey
fj ~ @~
i.I: 0!:!:: a: w Vl
w lL~ o z..J
::::>0
z w
~
0::
lL.
L-
SOIL DESCRIPTION
Vegetation: low brush and grasses.
Organics and organic silt, dark brown, very
soft,. moist. (PT-OL) (F-4)
Volcanic ash, sandy-silt to silty-sand, tan
silt overlying white sand, soft, moist.
(ML-SM) (.F-4)
9% Ft.
Vl w~ t w 0:::1-..
_J ::>z :z:: a.. t;;w 1-::E -1-a..
<[ oz w
fJ) :?!8 0
Organic silt, dark brown, contains some sand 1 1 ~ 5 _
and gravel -mostly at base, firm, moist.
~0-
I--
f--
I--
I--
~5
f-
..,___
(OL-SM) (F-4)
Sandy-silty gravel, light brown to gray with ~1f
depth, cobbles and boulders, angular to sub-
rounded gravels, mostly slate with some granites,
may contain random silt lenses, moist, dense to
very dense. Glacial till. (GM) (F-1)
S d d . . • /10· tan ar Penetratlon Test
1.4 split spoon and 70 lb. drop hammers
Depth Blow Count
6 I -6% I
6%1
-7 I
55
65
~5-
~QI I I I I 1~0
HOWARD GREY a ASSOC. INC.
LOG OF BORING NO. B-23
PROVECT Port Lions Hydroelectric
TYPE BORING 4" Auger
LOCATION Cresent Lake, 16+50' On Survey
_DATE July 19, 1980
SURFACE ELEVAT~N
Lin~OMPLETION DEPTH 7%_ Ft.
r-: .J ~
lL. 0~5 .. (J)
:I: fi: OLL.
w ~m
a ~s
z
l&J
N ~
lL. I ~ w~
0::1-
=>Z SOIL DESCRIPTION t;;w -1-oz (/)
=>u /
..-rv<'\
1-5
Vegetation: low brush and grasses.
Organics and organic silt, dark brown, very
soft.. (PT-OL) (F-4)
Volcanic ash, sandy-silt to silty-sand, tan
silt overlying white sand, soft, moist.
(ML-SM
Organic silt, dark brown, contains some sand
and gravel, firm, moist to wet.
(OL-SM) (F-4)
I
·j
::ES
t ..
I
1-a.. w
0
!!().
Sandy-silty-gravel, light brown to gray with
depth, cobbles and boulders, angular to sub-
rounded gravels, mostly slate but with some
granites, moist to wet, dense to very dense.
Glacial till. (GM) (F-1)
Standard Penetration Test
1.4 split spoon and 70 lb. drop hammer
J, I '~o.
q5
Depth Blow Count
6 I -6% I
6~' -7'
55
65
1-15·
201 I I I I 1!20
HOWARD GREY a ASSOC. INC.
LOG OF BORING NO. B-24
PROUECT Port Lions Hydroelectric DATE July 19 & 20,
TYPE BORING 4" Auger SURFACE ELEVATION
LOCATION Cresent Lake, 13+00' On Survey Lin€0MPLETION DEPTH
~ .....1~ z
1.1.. 0~53 w .. V> N ::r: 0
I-0 lL.. 0::
0... w (f) lL w lL (f)
o z::)l ~u /
SOIL DESCRIPTION
Vegetation: high bush
Organics and organic silt,
1980
6 Ft.
(/) w~ t w a:t-..
__J ::JZ: :r: a_ 1-W 1-~ V>f-a..
<( oz w
(/) ~0 0 u
moist. 1 1 1
1---
1---
10-
~
I--
I--
~
!'J 5·
Volcanic ash, sandy-silt to tan ~ilt
overlying white sand, soft, 1 1 1
silt, dark brown, contains some sands
firm, moist. (OL-SM) (F-4)
Sandy -silty-gravel, gray, contains angular to ~ sub-rounded gravels, cobbles and boulders, mostly J
slate with some granites, moist, dense to very
dense. Glacial till. (GM) (F-1)
1-5-
!10
15·
~0 I I I I I 1!20
HOWARD GREY a ASSOC. INC.
LOG OF BORING NO. B-25
PROJECT Port Lions Hydroelectric _DATE July 20, 1980
TYPE BORING 4" Auger SURFACE ELEVATION
LOCATION Cresene Lake, 50' North Of StreamCOMPLETION DEPTH 7 Ft.
t _.~
... 0 t:t ::r: (/) !..? fi: Ol.L
w ~~
0 ~:3 =>u
_A_i
z
UJ
N ~
lL
/
I~ w~
0::1-::::>z SOIL DESCRIPTION t;;w _.._
oz (/) ~0 u
Vegetation: high bush
a-: IJ.... ... ::r:
li: w
0
and organic silt, 1 1 1 1
{.~·.::·. . -. ~~: ...
: .; .. V:~ ...
I--
!'10-
45
Volcanic ash, sandy-silt to silty-sand, tan si~t. 1 1 1 1
overlying white sand, soft, moist.
(ML-SM) (.F-4)
silt,dark brown, contains some sand and
moist, firm. (OL-SM) (F-4)
Sandy-silty-gravel, gray, contains angular to
sub-rounded gravel particles, some cobbles and
~boulders, mostly slate with some granites, mo. 1· .s .. t. J to wet, dense to very dense. Glacial till. .
· (GM) (F-1)
.,
5-
y
:'10·
!'15·
~0 I I I I I 12()-
HOWARD GREY a ASSOC. INC.
LOG OF BORING NO. B-26
PROUECT Port Lions Hydroelectric DATE July 20, 1980
TYPE BORING 4" Auger SURFACE ELEVATION
LOCATION Cr~sent Lake, 15+00 On Survey LineCOMPLETION DEPTH 5 Ft.
,....: _J ~
lL. 0~ 1-:: .. lf) I
1-OLL a. w-w -~
a ~::3
:::>u
f-.-
f--
!J()..
f--
45·
z w
N
ft
LL
/__-
\
\
0 r: (/) wi>' LL w 0::1-...
_J :::::>z I
SOIL DESCRIPTION a. t;;w t ~ -1-<{ oz w
(/) :ES a
Vegetation: low brush and grasses.
organic silt, 1 1 1
Volcanic ash, sandy-silt to silty-sand, tan silt 1 1 1 overlying white sand, soft, moist. · '
(ML-SM) (F-4)
Organic silt, dark brown to gray, contains some
sand and gravel, moist, firm.
(OL-SM) (F-4)
Sandy-silty-gravel, light brown, angular to
sub-rounded gravel, contains cobbles and boulders,
moist, dense to very dense, drilling difficult,
refusal on boulder or bedrock. Glacial till.
(GM) (F-1) }
I I I 5 ·
~0-
.. 15·
~o· 1 , • , •2 o-
HOWARD GREY a ASSOC. INC.
~ z -1-
CCI C/)
l.J.J >< 1--Q >· z 0::::
l.J.J c
0-1-
0.... c::::( c:::c 0::::
0
CCI
<l::
........1
100
90
..... 80
X
~ 10 LIJ
~
>-60 m
a:: ~ LIJ
~
LL
..... 40 z
LIJ
~ 30
LIJ a.
20
10
U. S. STANDARD SIEVE SIZE
3in. 1.5in. 3/4in.3/8in 4 I 0 20 40 60 100 200 HYDROMETER I . I _1 I
t'
~
"" "'" ~
~ w ~
I~
[ ~ ffi " '\
I'
~'-ro...
...... ~'-..
-..............
100 10 1.0 0.1 0.01
GRAIN SIZE IN MILLIMETERS
COBBLES GRAVEL SAND SILT COARSE I FINE COARSEI MEDIUM 1 FINE
Cresent Lake Damsite
PROJECT Port Lions Hydroelectric WORK ORDER 80-339
Boring DHIH Sample DH#J Depth 3 Et Dust Ratio 0/o Passing 200 10. 6%
Based on visual observation, an estimated 10% of this soil is greater
than 3 inches.
GRAIN SIZE DISTRIBUTION
HOWAFI> GREY a ASSOC. INC.
0.001
CLAY
100
90
~ 80
:I:
~ 70 UJ
~
>-60 CD
ffieo
i: u.
~ 40 z
UJ
~ 30
UJ
0...
20
10
U. S. STANDARD SIEVE SIZE
3in I 5in 3/4in.318in 4 I 0 20 40 60 100 200 HYDROMETER i . , I I I
""' ~
" ""' "" "" ,,.,.
~
~
~
"
~
~
I"
"
fF
100 10 1.0 0.1 0.01
GRAIN SIZE IN MILLIMETERS
COBBLES GRAVEL SAND SILT COARSE I Fl N E COARSel MEDIUM I FINE
Cresent Lake Damsite
PROJECT Port I.j ons Hydroelectric WORK ORDER .80,339
Boring DH{!2 Sample DH#2 Depth 4 Ft. Dust Ratio __ 0/o Passing 200 J 4 4%
Based on visual observation, an estimated 10% of this soil is greater
than 3 inches.
GRAIN SIZE DISTRIBUTION
HOWAFD GREY a ASSOC. INC.
0.001
CLAY
U. S. STANDARD SIEVE SIZE
100
3in. 1.5in. 3/4in.3/8in 4 I 0 20 40 60 100 200 HYDROMETER 'I I I
90 ~
~
.... 80
:t: ' " ~ 10 UJ
~
>-60 CD " ,,
0:: ~ UJ
i; " ~ u..
t-40 ' z
UJ u 30 a::
IJJ
' " Q.
20 " ' 10 1-
100 10 1.0 0.1 0.01
GRAIN SIZE IN MILLIMETERS
COBBLES GRAVEL SAND SILT CLAY COARSE I Fl N E COARSE! MEDIUM I FINE
Forebay Damsite
PROJECT Port Lions Hydroelectric WORK ORDER 80-339
Boring B-12 Sample B-12 Depth 4 Ft. Dust Ratio __ _ 0/o Passing 200 11. 8%
Based on visual observation, an estimated 5% of this soil is greater
than 3 inches.
GRAIN SIZE DISTRIBUTION
HOWARD GREY a ASSOC. INC.
0.001
100
90
.... 80
X
£2 70 LLJ
;t
>-60 c:o
0: ~ w
~
LL
.... 40 z w
~ 30 w a.
20
10
U. S. STANDARD SIEVE SIZE
3in I 5in 314in 3/Sin 4 I 0 20 40 SO 100 200 HYDROMETER i 'I I I I
r-... t--.....
~
' \
~·
\
~
\
\
\
1\
' ' ....._
100 10 1.0 0.1 0.01
GRAIN SIZE IN MILLIMETERS
COBBLES GRAVEL SAND SILT COARSE I FINE coARsEI MEDIUM I FINE
Forebay Damsite
PROJECT Port Lions Hydroelectric WORK ORDER 80-339
Boring B-l 4 Sample B-l 4 Depth 6 Ft · Oust Ratio 0/o Passing 200 6 · 5%
Based on visual observation, an estimated.lO% of this soil is greater
than 3 inches.
GRAIN SIZE DISTRIBUTION
HOWARD GREY a ASSOC. INC.
0.001
CLAY
PROJECT: Port Lions llydroe]ectric
DATE: 1980
PLASTICITY CHART
40
CH -H
p.. ->< 30
~
Q z
H
>-t
H
H CL u 20 H
H
C/l < ....:l p..
MH or OH
10
CL-:t-!L
ML or OL
10 20 30 40 50 60 70
LIQUID LIMIT (LL)
..::::r
I -" 1'1"\ c...D
u " I I
U') l'l"'INN
>< w " I -0::::: u -" " ~ ~ " C'.J ~
z (.!:) c::Q " I I
w -" NNN
c.. L.L.. c:c I
c.. -" " c::t: -..::::r
I I -N N
I -
......
1.
~ ';
L•
l.-~
'"7 . ~,--. j_. \r,\\~<f,;.,;, l/-v•) V'-._5 ( 4/fl
-....... J \ ,, --\\. ---.__... ..... 7 ' 1
t 22 ('\
. d'
\_;"
(
../ . ~.;-'
\ 27
. \ /-r
/
.~
/'
t'A ·r-.
#
• I! I
'Q_
---,-:P//
' ·~ /)
,\
&TO'Oul
. ..
• ~ -4>
Pokati
-~ •. ~AMSITE
a..._:.'..-~":"'«2
•
~
-.;:
::....
~
:::
~
......
~
Pestchani
Pomt
Q=
"' ~
~
"I'~ .'""' '-{ -c\j -~-0 \....-~ l . ---
""'' ~ .... "(J()C~ Uzko~sl<f ,:;,, • ', 7'. _./
Po1nt ~
.;b o--c.'~·
~ .J> Bird.._ •.,.,.::;. __ _,-•
.j> ~ Pomt .. ~uzhn
~ e Pomt
0 ,,.,..,.,
RocO
• Sftoc Rod<l
VICINITY MAP
PORT LIONS, ALASKA
From U.S.G.S. Kodiak (D-3)
Figure ~
J s
I
I
u/o ,
, I
,
I
I
I
I
I
, ,
J s
Trinity Islands ? s 10 15 70 31
Scale-Miles
y'k
Kodiak Island
~
N
"
EXPLA~ATION
Jurassic, volcanic and
marine sedimentary rocks
oz.-1 Cretaceous, slates and
~ graywackes
~ Tertiary, shales, sand-
stones and conglomerates
u Major fault showing
----~ 0 relative movement
by: C.A. Burk
Published by: The Geological Society
of America, Inc., 1965
TECTONIC HAP
KODIAK ISLAND f£ VICINITY
Figure B
\
CRESENT LAKE AREA
Cresent
Lake
Island
Lake
Kk_.Q
I ~q~H Recent:
~g~ Pleistocene:
[~-~~~Cretaceous:
PORT LIONS AREA
SCALE
1 11 = 1000 I
Undifferentiated alluvial gravel and sand
Glacial moraine deposits, unconsolidated silt, sand, and gravel
Slates and graywacke. generally highly metamorphosed and well
indurated.
GENERALIZED GEOLOGIC MAP
CRESENT LAKE & PORT LIONS AREA
ALASKA
Figure C
----------------" -I· .. \ --.. ... _. '
85
, ... - s -... ~1-2 -· .. ---{ ""f Rebar ,. "'"'""' __ ...
... ,; .
........ "'I .. ,_,--~~"' I
e
DII#B-14
~-----------------I -----
\ ~+.QQ.,' _ \. __________ - - -""' ,.. -TP-4
--~,..-
-....................
\
0
---/ \ Hub ' ----·,----------------.\----
.......
.
\
\ ___ \ ________ _
..... .,..
\
\ v
sc'-Y
\
Port Lions
River
... ~ "" , ,..
______ .... -, / ,
----..... _____ 75
\
~
,
,;
,; ,
"' ""'
/
/ , .,
80
/
/
/ ,. -
--
"
"" ""
"" ,.
,; ,
,
/
/
/ ,;
""
/
;'
/ ,
/ \ /
.....
,
"
SCALE
1" = 20'
\
\
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
"" /
'""\
/
• I
)./ ,· ,.,. \
\
/ \
\
\
\
,."'
/
\
\
/
'
Elevation Contours
II II Cross Section
1--.?~1-1 ... ---1 Seismic Line
~ Test Hole
y Strike & Dip
I
I
I
I
I
I
I
I
I
I
I
I
I
Topor,raphy Elevations & Facility Locations
Taken From Damsite Survey
-/ .... / ..... ,.
,.,.."'
( ~ -,.
_,...---·---. --I ----75
,,. , 0 Hub \ _.,,.
I
I
I
I
I
12+25' .
\
/
I
\
~,"'
\ 12+50.,. /.
/ \
/
/
/
. /
\"'"" \
--,. .... 80
"" ,
~ DH:f,fB-12\
\12+75' \
\ ,.. ,.--85 .
\..,""
-
..,.,.
... -....
... .... .... -.....
' I
, , "" \
I
I
I
'-I
~.
I
I
I
I
I
I
I
I
(
I
I
I
I
I
I
I
I
I
I
I
I
I '· '\. I ,,
I
I
I
I
I
I
I
I
f
I
I
r
I
I
,,
I
I
{
I
I
I
I
I
I
' '·
I'
I
I
.... ...
,.
;
;
\
\
\
\
90··
Spillway
PORT LIONS HYDROLELECTRIC
FOREBAY DAHSITE
P'lan View
.....
,.
,
/
.....
-
.... .....
,
....
....
' '
n Figure No.l-1 ..
North
sc 1-2
100' c r
..;:t
90' .......
I
c:Q
80'
70'
60'
sc 1-1
sc 1-3
N
.......
I
c:Q
.......
.......
I
c:Q
-------------------__::._----- -
---------------------_---------
~Surface:
Moraine:
Till:
Bedrock:
Organics, Volcanic Ash, Organic Silt
Clayey-S'l 1 ty-Gravell y-Sand
Silt-Gravell S y-and
Slate, Graywacke
Contact, Dashed Hhere Approximate
sc 1-L~
("'")
.......
I
c:Q
~ ::r::
P.
---------------:.--------~ ---------
SCALE ---
Horizontal: 1 11 = 25'
Verticle: 1" = 10'
Verticle Ex aggeration: 2.5x
Topograph~ & Surface
Taken From Dam . Elevations Sl.te Survey
South
C' 100'
90'
80'
70'
60'
PORT LIONS L HYDROELECTRIC
FOREBAY DAHSITE
Cross Section
Figure No.l-2
\>Jest
90 I -
80 1
-
70'
60 1
-
t-Jes t East
Ground Surface 75'~------------------------~~~-------------------75'
vl = 850 ft/sec
v2 = 9000 ft/sec
65 I-LINE SCl-1 1-65 I
Topography & Elevations
Taken From Damsite Survey
Ground Surface
vl = 825 ft/sec
v2 = 3450 ft/sec
v3 = 13,700 ft/sec
East
90'
80'
70'
LINE SCl-2
• 60 I
SCALE
Horizon tal: 1 '' = 10'
Vertical: 1" = 10'
PORT LIONS HYDROELECTRIC
FOREBAY DAHSITE
SEISMIC VELOCITIES
Figure No. l-3
North
80'
70'
60'
North
90'
80'
d su-rface --------G-roun ---
1100 ft/sec
v 2 = 16,ooo /sec
South
Ground Surface
90'
1100 /sec
80'
v2 = 16,000 ft/sec
70'
LINE SCl-4
Topography & Elevations
~aken From Damsite Survey
South
90'
80'
70'
LINE SCl-3
SCALE
Horizontal: 1" = 10'
Vertical: 1" = 10'
PORT LIONS HYDROELECTRIC
FOREBAY DAMSITE
SEISMIC VELOCITIES
Figure No. 1-4
)( 299.4
\
J
I
,...:..._. --.....
" \
r----::.··\
)( 299. 7
. .. --···\..~296.7
I
I
J
.... 308.8~.
31..~30 8
SC2-6
"-;;I;
308.6
)(316.6
x'319.8 -------
CRESENT LAKE
(]1-----[] Survey Line and Stations
ft-----------1 Cross Section
SC2-l Seismic Lines
0 Test Holes (Boring)
Test Pits
~ Strike and Dip of Outcrop
X Elevations
SCALE
1" = 100'
X 311.7
')(315.2
~ (
~-/
'\
PORT LIONS HYDROELECTRIC
CRESENT LAKE DAMSITE
Plan View
Figure No. 2-1
/
North
A0 SC2-2
340' I
320'
300'
SC2-l
I
fps
SC2-7
N
~ ::c
c:l
~
...;:t
N
South
SC2-6 SC2-5 SC2-4 SC2-3 --..... A' 340'
320'
r-1
N
300'
280'
------------------------------------
260'
West
320'
300'
280'
I SC2-l
East
B'
320'
300'
280'
·~ Surface: Organ~s, Volcanic Ash, Organic Silt
~ Till: Silty-Gravelly-Sand
~ Bedrock: Slate, Graywacke, Irregular & \olea thered Surface
SCALE
Horizontal: 1" = 100'
Verticle: 1" = 20'
Topography & Elevations
Taken From Damsite Survey
PORT LIONS HYDROELECTRIC
CRESENT LAKE DAMSITE
Cross Section
260'
Figure No. 2-2
West
315'
305'
29 5'
285'
\-Jest East
300'------------------------------------------------------------------------~ 300'
290'
280'
270'
---.............
-------
v1 = 1050 ft/sec
v2 = 6000 ft/sec
Topography & Elevations
Taken From Damsite Survey
vl = 950 ft/sec
v2 = 2500 ft/sec
v3 = 9000 ft/sec
LINE SC2-2
---
------
LIUE SC2-1
East
305'
295'
285'
290'
280'
270'
SCALE
Horizontal: 1"
Vertical: 1"
10'
10'
PORT LI0:1S HYDROELECTRIC
CRESENT LAKE DAMSITE
SEISlUC VELOCITIES
Figure No. 2-3
North
305'
295'
285'
North
300'
290'
------
280'
270'
1050 ft/sec
6000 ft/sec
------------v3 ~ 20,000 ft/sec
vl ~
v2 =
v3 =
1150 ft/sec
9250 ft/sec
17,000 ft/sec
Topography & Elevations
Taken From Damsite survey
LINE -----
South
305'
295'
285'
LINE SC2-3
South
300'
SCALE
Horizontal: 1" = 10'
290' Vertical: l" = 10'
280'
PORT LIONS HYDROELECTRIC
CRESENT LAKE DAMSITE
SC2-4 SEISIHC VELOCITIES
270'
Figure No. 2-4
325 I •
315 I •
305'
295'
285 I •
North South
I"" 325'
r-------------------------------------------------------------------------~
vl == 1075 ft/sec
v2 = 4450 ft/sec
Bedrock Depth Greater Than 40' ----------------------------------------
V3 = Estimated at 10,000 ft/sec
Topography & Elevations
Taken From Damsite Survey
LINE SC2-5
"" 315'
.... 295'
1-285'
SCALE
Horizontal: 1" = 10'
Vertical: 1" = 10'
PORT LIONS HYDROELECTRIC
CRI:SENT LAKE DAHSITE
SEISMIC VELOCITIES
Figure No. 2-5
I
I
I
I
I
I
I
I
I
I
I
I North
305 1
I
I 295 1
I
I 285 1
I --
I
I
South
~N:o:r~t:h--------------------------------------------------------------------------------------l
305' ~ 305'
vl :::; 1100 ft/sec
295 1 295'
v2 :::; 5800 ft/sec
285' 285'
LINE SC2-6
--------------------------
---------------Bedrock Depth Greater Than 32 1
275 1 275'
------------
vl = 1100 ft/sec
v2 = 3000 ft/sec
------
v3 = 13,000 ft/sec
Topography & Elevations
Taken From Damsite Survey
-........
........ LINE SC2-7
........
........
........ .....
South
305 1
295'
I
l 285'
SCALI:
Horizontal: 1 11 = 10 1
Vertical: 1 11 = 10 1
PORT LIONS HYDROELECTRIC
CRESENT LAKE DAi~SITE
SEISMIC VELOCITII:S
Figure Ho. 2-6
I
----------------