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SUSITNA HYDROELECTRIC PROJECT
1980-81 GEOTECHNICAL REPORT
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VOLUME 1
TEXT
FINAL DRAFT
ARLIS
Alaska Resources
Library & Infmmatton Servtces
Anchorage, Alaska
L..---ALASKA POWER AUTHORITY __ ____.
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ALASKA POWER AUTHORITY
SUSITNA HYDROELECTRIC PROJECT
1980-81 GEOTECHNICAL REPORT
TABLE OF CONTENTS -VOLUME 1
LIST OF TABLES
LIST OF FIGURES
1 -INTRODUCTION .•..•...•......•...•.......•.•..•...........•..
1.1 -General ...•..•....•.....•..•..•.....................
1.2-Project Description and Location •....•.••.....•.•...
1. 3 -Plan of Study ..................•.•......•..•.•..•..•
1. 4 -Report Contents ..•••....••....•.••..•......•........
1.-5 -Acknowledgements •.••..•......•....•.................
2 -SUMMARY AND CONCLUSIONS ••....•.......•....•..•.•.••......•
2. 1 -Introduction .......••.•..•....•.....•.•.•.........••
2.2 -Watana Site •.•..•..•.••...•.•.............•••....•..
2 . 3 -De vi 1 Canyon S i te .•••.•••.•..•....••.•.••...••..•.••
3 -REVIEW OF PREVIOUS INVESTIGATIONS .•.....•......•.......•..•
3.1 -Introduction .......•..•..•...•...•...•...•.•.•...•.•
3. 2 -Watana ......••....••.••.•.••.••.•.•••..•....•.....•.
3. 3 -Dev i 1 Canyon ..........••.••....••.•.•.•....••.•.....
3. 4 -Conclusions .... -.....................•..•...•.•....••
4 -REGIONAL GEOLOGY ...•.......•....•..•.••.•.••.•............
4.1 -Introduction ..••..•......••.••.••...•....•.•..•.....
4.2 -Stratigraphy ..•....•..•..••••..•.•......••.•.•......
4.3-Tectonic History ...•.............••........••..•.••.
4.4 -Glacial History •.•...•.•..••.•.........•...••........
5 -SCOPE OF GEOTECHNICAL INVESTIGATION ......••••.••...•......
5.1 -Introduction ...••.•..•••...•••....••...•.••.•.•.....
5.2 -Geologic Mapping ................................... .
5.3-Subsurface Investigation .•.........•....•.••...•..•.
5.4 -Seismic Refraction Surveys ........................ ..
5.5-Borrow Investigation .•.•.•...............•..........
5.6 -Laboratory Testing .•...•..•••.•..•.•....•..•.•....••
6 -RESULTS OF GEOTECHNICAL INVESTIGATIONS -WATANA .•.•.•••..•
6.1 Watana Dams i te ...•....••....••••.........•.•..•.•.••
6. 2 -Relict Channel .•••.•.••.•••••••.•..•....•.••...•....
6. 3 -Borrow and Quarry t~aterial ........................ ..
7 -RESULTS OF GEOTECHNCIAt INVESTIGATIONS-DEVIL CANYO~ •.••.
7.1 -Devn Canyon Damsite .•.•....••..•.•..•••.••.....••..
7.2 -B-orrow and Quarry Material ......................... .
REFERENCES
GLOSSARY ARLIS
Page
1-1
1-1
1-1
1-2
1-4
1-5
2-1
2-1
2-1
2-4
3-1
3-1
3-1
3-2
3-3
4-1
4-1
4-1
4-2
4-2
5-1
5-1
5-1
5-4
5-6
5-7
5-8
6-1
6-1
6-1
6-32
7-1
7-1
7-27
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Alaska Resources
Library & In.format1on Servtces
Anchorage. Alm'lka
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ALASKA POWER AUTHORITY
SUSITNA HYDROELECTRIC PROJECT
1980-81 GEOTECHNICAL REPORT
TABLE OF CONTENTS -VOLUME 2
APPENDIX A-Selected Bibliography of Previous Investigations
APPENDIX B-Watana Diamond Core Drilling Logs
APPENDIX C -Devil Canyon Diamond Core Drilling Logs
APPENDIX D -Watana Water Pressure Testing Details
APPENDIX E -Devil Canyon Water Pressure Testing Details
APPENDIX F -Watana Borrow Site Investigation
F.l-Borrow SiteD
F.2 -Borrow Site E
F.3 -Borrow Site H
f.4 Borrow Sites I & J
APPENDIX G -Devil Canyon Borrow Site Investigation
G.1-Borrow Site G
APPENDIX H -Seismic Refraction Survey -1980
APPENDIX I -Seismic Refraction Survey -1981
APPENDIX J -Airphoto Interpretation
APPENDIX K-Reservoir Slope Stability
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LIST OF TABLES
Table No.
3.1
3.2
3.3
3.4
3.5
4.1
5. 1
5.2
5. 3
5.4
5. 5
5. 6
5. 7
5. 8
5. 9
5.10
6.1
6.2
6. 3
6.4
6. 5
6.6
6.7
6.8
6.9
6.10
6.11
6.12
7.1
7. 2
7.3
7. 4
7.5
7.6
7.7
7.8
Title
Summary of Previous Investigations -Watana Damsite
Summary of Previous Investigations -Borrow Site 0 -
Watana
Summary of Previous Investigations -Borrow Sites E, F,
and C -Watana
Summary of Previous Investigations -Devil Canyon
Damsite
Summary of Previous Investigations -Borrow Site G -
Devi 1 Canyon
Geologic Time Scale
Summary of the 1980-81 Investigation -Watana Damsite
Summary of the 1980-81 Investigation -Devil Canyon
Damsite
Summary of the 1980-81 Seismic Refraction Line Data
Summary of 1980-81 Investigation -Borrow Site D -
Watana
Summary of 1980-81 Investigation -Borrow Site E -
Watana
Summary of 1980-81 Investigation-Borrow Site G -Devil
Canyon
Summary of 1980-81 Investigation -Borrow Site H -
Watana
Summary of 1980-81 Investigation -Borrow Sites I and
J -Watana
Summary of Rock Tests -Watana
Summary of Rock Tests -Devil Canyon
Watana Seismic Velocity Correlations
Watana Joint Characteristics
Watana RQD Summary
Watana Borehole Rock Quality Distribution
Watana Rock Test Summary -Diorite, Quartz-Diorite,
Granodiorite
Watana Rock Test Summary -Andesite Porphyry
Quaternary Stratigraphy of Buried Channel Area
Material Properties -Borrow Site D
Gradation Results -Borrow Site D
Material Properties -Borrow Site E
Material Properties -Borrow Site H
Material Properties -Borrow Sites I and J
Devil Canyon Seismic Velocity Correlations
Devil Canyon Joint Characteristics
Devil Canyon Tailrace Tunnel -Joint Characteristics
Devil Canyon RQD Summary
Devil Canyon -Borehole Rock Quality Distribution
Devil Canyon Rock Test Summary -Mafic Dikes and
Argillite
Devil Canyon Rock Test Summary -Graywacke
Material Properties -Borrow Site G
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LIST OF FIGURES
Figure No.
1. 1
1.2
1. 3
4.1
5.1a
5.1b
5. 2
5.3
5.4
6.1
6.2
6.3
6.4
6.5
6.6
6. 7
6.8
6.9
6.10
6.11
6.12
6.13
6.-14
6.15
6.16
6.17
6.18
6.19
6. 20
6.21
6.22
6.23
6.24
6.25
6.26
6.27
6.28
6.29
6.30
6.31
6.32
6.33
6.34
Title
General Location Map
Watana General Arrangement
Devil Canyon General Arrangement
Regi anal· Geology Map
Watana: Damsite Vicinity Exploration Map
Watana: Exploration Map
Devil Canyon Exploration Map
Borehole Typical Instrumentation
Borehole Typical Instrumentation
Watana Index Map
Watana Top of Bedrock and Surficial Geologic Map
Watana Geologic Map ·
Watana Geologic Section W-1
Watana Geologic Section W-2
Watana Geologic Section W-3
Watana Geologic Section W-4
Watana Geologic Section W-5
Watana Andesite Porphyry Flow Structure and Inclusions
Watana Fracture Zone in Andesite Porphyry
Watana Felsic Dike in Diorite
Watana Joint Station Plots
Watana Composite Joint Plots
Watana Typical Shear
Watana Shear/Alteration Zone
Watana "The Fins"
Watana Geologic Features GF4A, GF4B, and GF5
Watana Geologic Features Downstream of Centerline
Watana 11 Fi ngerbuster" Area North Bank
Watana Geologic Feature GF7B
Watana Rock Tests
Watana Static Elastic Properties for Andesite and
Diorite
Watana Direct Shear Tests
Watana Unconfined Compressive Strength Test Results
Watana Point Load Test Data
Watana Rock Permeability
Watana Thermistor Data
Watana Thermistor Data -Relict Channel
Watana Thermistor Data -Borrow Site H and Borrow Site D
Watana Relict Channel Photos
Watana Relict Channel Section
Watana Relict Channel and Borrow SiteD/Stratigraphic
Fence Diagram Sheets
Watana Relict Channel -Expanded Thalweg Section
Watana Relict channel Profiles
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LIST OF FIGURES (Cont•d)
Figure No.
6.35
6.36
6.37
6.38
6.39
6.40
6.41
6.42
6.43
6.44
6.45
6.46
6.47
6.48
6.49
6.50
6. 51
6.52
6.53
6.54
7.1
7.2
7. 3
7.4
7. 5
7.6
7. 7
7.8
7.9
7.10
7.11
7.12
7.13
7.14
7.15
7.16
7.17
7.18
7.19
7.20
7.21
7.22
7.23
Title
Relict Channel -Top of Bedrock
Watana Quarry and Borrow Sites Index Map
Watana Quarry Site A -Plan and Sections
'quarry Site B -Plan and Sections
Borrow Sites C and F
Borrow Site D -Plan
Watana Borrow Site D -Range of Gradations
Watana Borrow Site D -Material Gradation Types
Borrow Site E -Plan
Borrow Site E -Sections
Watana Borrow Site E -Range of Gradations
Watana ~orrow Site E -Stratigraphic Unit Gradations
Borrow Site C and F -Range of Gradations
Borrow Site H -Plan
Watana Borrow Site H -Range of Gradations
Watana Borrow Site H -Stratigraphic Unit Gradations
Borrow Site I -Plan
Borrow Site J -Plan
Borrow Sites E, I, and J -Photos and Typical Sectio~s
Quarry Site L -Plan and Sections
De vi 1 Canyon Index Map
Devil Canyon Top of Bedrock (lnd Surficial Geologic Map
Devil Canyon Geologic Map
Geologic Sections DC-1
Geologic Sections DC-2
Geologic Sections DC-3
Geologic Sections DC-4
Geologic Sections DC-5
Geologic Sections DC-6
Geologic Sections DC-7
Devil Canyon Typical Argillite/Graywacke
Devil Canyon Aerial View of Site
Devil Canyon Joint Plots
Devil Canyon Tailrace Geology
Devil Canyon Rock Tests
Devil Canyon Static Elastic Properties for Argillite and
Graywacke
Devil Canyon Direct Shear Tests
Devil Canyon Unconfined Compressive Strength Test
Results
Dev·i 1 Canyon Point Load Test Data
Rock Permeability
Thermistor Plots -Damsite
Borrow Site G -Plan
Borrow Site G -Sections
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LIST OF FIGURES (Cont'd)
Figure No.
7.24
7.25
7.26
Title
Devil Canyon Borrow Site G -Range of Gradations
Devil Canyon Borrow Site G -Stratigraphic Unit
Gradations
Devi 1 Canyon -Quarry Site K
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1 -INTRODUCTION
1.1 -Genera 1
The Susitna Hydroelectric Project is located within the upper reaches
of the Susitna River basin in south-central Alaska (Figure 1.1). The
feasibility studies for hydroelectric development were performed by
Acres American Incorporated (Acres) under contract to the Alaska Power
Authority (The Power Authority).
The overall objectives of the study were:
-To determine technical, economic and financial feasibility of the
Sus itna Hydroelectric Project to meet the future power needs of the
Railbelt Region of the state of Alaska;
-To examine the environmental consequences of constructing the Susitna
Hydroe 1 ectr i c Project;
-To file a license application with the Federal Energy Regulatory Com-
mission (FERC) should the project be deemed feasible.
As part of the Plan of Study (POS), a geotechnical exploration program
(Task 5) was undertaken at the proposed project locations at Watana and
Devil Canyon. The purpose of this report is to present a detailed des~
cription of the geologic and geotech~ical conditions at these sites.
1.2 -Project Description and Location
The Watana and Devil Canyon sites had been previously identified by the u.s. Army Corps of Engineers (COE) and the u.s. Bureau of Reclamation
(USBR) over a period of years from 1952 to 1979.
The scheme calls for a large embankment dam with an underground power-
house ·at Watana and a high concrete dam with underground powerhouse at
the Devil Canyon site. General site arrangements are shown in Figures
1. 2 and 1. 3.
The area of study is 1 ocated within the Coast a 1 Trough Provi nee of
south-central Alaska, with a drainage of approximately 6, 000 square
mi 1 es. The· Sus itna River is glacier-fed, with headwaters on the south-
ern slope of the Alaska Range. From its proglacial channel in the
Alaska Range, the Susitna River passes first through a broad, glaci-
ated, intermontane valley of knob and kettle and braided channel topo-
graphy. Swinging westward along the edge of the Copper River lowlands,
it enters the deep U-shaped valleys which include the proposed dam-
sites, winding through the Talkeetna Mountains until it emerges into a
broad glacial valley leading to Cook Inlet near Anchorage.
1-1
The Watana site is located at approximately river mile 184 between
Tsusena and Deadman Creeks. The Watana damsite is located in a rela-
tively broad U-shaped valley rising in steps, with a steep lower por-
tion breaking into somewhat flatter slopes and becoming much gentler
near the top. Access to the lower sections is limited by vertical rock
outcrops. Gravel bars, some of which are quite wide, are exposed in
the river bed during low water flows. The river at this site is
approximately 500 feet wide and is relatively turbulent and swift flow-
ing.
The Devil Canyon site is located on the Susitna River 14 miles upstream
from the Alaskan Railroad, 140 miles north of Anchorage, and 160 miles
south of Fairbanks. The site is located at approximate river mile 152
(32 river miles downstream from the Watana site). At the Devil Canyon
site, the river enters a very narrow 11 V11 -Shaped gorge about two miles
in length with steep walls up to 600 feet high. The damsite is several
hundred feet downstream from the entrance of Devil Canyon. The valley
is generally asymmetrical in shape, with the north abutment sloping at
about 45° and the south abutment steeper, about 70°. The south abut-
ment displays overhanging cliffs and detached blocks of rock. The
north abutment is somewhat less rugged in the upper half, the lower
portion is very steep. Access at river level is very limited, but nar-
row benches are accessible at low water levels. The Susitna River in
Devil Canyon is approximately 150 feet wide and very turbulent. The
canyon itself is approximately 1,000 feet wide at the proposed dam
crest elevation.
1.3-Plan of Study
(a) Objectives
The objectives of the Task 5 studies were to determine the surface
and subsurface geology and geotechnical conditions for the feasi-
bility of:
- A 1 arge rockfi 11 dam, underground powerhouse, and associated
structures at Watana site;
- A concrete dam with underground powerhouse and associated struc-
tures at Devil Canyon site;
-Transmission line to connect the proposed development with the
existing power grid system; and
-Access roads to the proposed development.
(b) Scope
The task was subdivided into a series of subtasks to meet the
overall abjecti ves. The s4btasks and their corresponding objec-
tives were:
1-2
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Subtask
5.01 -Data Collection
and Review
5.02-Airphoto
Interpretation
5.03 -Exploratory Program
Design (1980)
5.04 -Exploratory Program
(1980)
5.05 -Exploratory Program
Design (1981}
5.06 -Exploratory Program
{1981}
1-3
Objectives
To collect and review all existing
geological and geotechnical data
pertaining to the project includ-
ing the access road and transmis-
sion line corridors and the upper
Susitna River basin.
Perform airphoto interpretation
and terrain analysis of the Watana
and Devil Canyon damsite area,
reservoir areas, borrow sites and
access road, and transmission line
corridors, and identify adverse
geological features and geotechni-
cal conditions that could signifi-
cantly affect the design and con-
struction of project structures.
Design the geotechni ca 1 expl ora-
tory investigation programs for
1980 for Watana and Devil Canyon
damsites, dam construction materi-
als, and reservoir areas, and
along the access road route.
Perform initial surface and sub-
surface program investigations at
Watana and Devil Canyon sites and
reservoir areas and access road
routes to estab 1 ish genera 1 and
specific geological and foundation
conditions.
Design the geotechnical explora-
tory ·investigation program for
1981 for Watana and Devil Canyon
damsites, dam construction materi-
a 1 s and reservoir areas, and for
the selected access road and
transmission line routes.
Complete surface and subsurface
investigations at Watana and Devil
Canyon damsites, reservoir areas,
access roads, and transmission
1 i ne routes to the extent neces-
sary to provide adequate data to
confirm project. feasibility and
for submission of FERC license
application, currently scheduled
for September 1982.
5.07 -Exploratory Program
Design (1982-1984)
5.08-Data Compilation
(c) Approach
Design of the geotechnical explor-
atory investigation program for
1982 to 1984 to obtain basic
design data for Watana damsite,
dam construction materials, and
reservoir areas, and for the sel-
ected access road and transmission
line routes.
Assemble all geotechnical explora-
tory data into documents suitable
for inclusion in relevant project
reports and 1 i censi ng documenta-
tion.
To meet the objectives of the task in an orderly and timely man-
ner, the geotechnical exploratory programs were divided into three
stages: the 1980 activities, the 1981 activities, and the activi-
ties during and after 1982 (after the FERC license application is
submitted). The 1980 geotechnical activities were planned to
identify and investigate in limited detail, those geological and
geotechnical conditions which had been identified by previous
studies that may have an effect on the feasibility of the project.
These activities included Subtasks 5.01 through 5.04.
Subtasks 5.05 through 5.08 were undertaken during 1981 and early
1982, respectively. Under these activities, a more detailed study
was made of those geological and geotechnical conditions identi-
fied during the 1980 studies as warranting further investigation.
The 1981 program also included the investigation for the access
roads and the transmission 1 i nes. These data were subsequently
inputs into other task activities for final presentation.
It should be noted that the findings and conclusions presented in
this report are based on a limited scope of geotechnical investi-
gation and that more detailed investigations will be undertaken in
the subsequent phases of the project.
1.4 -Report Contents
This Geotechnical Report is presented in seven sections. A summary and
preliminary conclusions of the studies are presented in Section 2; a
review of previous work undertaken by the COE, USBR, and others is pre-
sented in Section 3; a preliminary assessment of regional geology is in
Section 4; the scope of the 1980-81 geotechnical exploration program is
presentedin Section 5; and the results of the study in Sections 6 and
7. A comprehensive bibliography of geotechnical information for the
site area was compiled during Subtask 5.01 and is presented in Appendix
A. Detailed results of drilling, testing, seismic refraction surveys,
1-4
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airphoto interpretation and reservoir mapping performed during the pro-
ject are included in Appendices B through K. Engineering significance
and application of the data developed in Task 5 and presented in this
report have been addressed in the Susitna Feasibility Report (1}. This
study, therefore, stands as a referenced document to that report.
1.5 -Acknowledgements
Some material presented in this report has been obtained from reports
previously published by the USBR and others. The cooperation of the
COE in providing access to records and data and opinions on interpreta-
tion is gratefully acknowledged.
Drilling at the sites was performed by The Drilling Company (TDC} and
Interstate Exploration, Inc., under the direct supervision and direc-
tion of Acres staff and R&M Consultants, Anchorage, A 1 ask a. Seismic
refraction surveys were performed by Woodward-Clyde Consultants. In-
hole geophysical logging work was by EDCON (Exploration Data Consul-
tants, Inc., of Denver, Colorado). Airphoto interpretation was done by
R&M Consultants, and laboratory testing by R&M and Acres.
Logistical support during field activities was provided by KNIK/ADC -
Joint Venture under its subcontract with Cook Inlet Region, Inc./Holmes
& Narver, Inc., and Acres for camp accommodations, and by Akland Heli-
copters, ERA Helicopters, Air Logistics, Inc., also under subcontract
with Acres, for personnel and equipment transportation requirements.
The results of these activities were presented to the Acres External
Review Panel (Dr. R. Peck, Dr. s. Hendron, Mr. M. Copen), to the Power
Authority, and to the Power Authority Review Board Members (Dr. H. Seed
and Dr. A. Merritt) during technical meetings and discussions. Acres
is very grateful for their critical and very objective review of the
information. Thanks are dueto Mr. L.A. Rivard for his contributions
to Subtask 5.02 -Airphoto Interpretation.
1-5 ~~il
GENERAL
S K A
GULF 0 ALASK.
KEY MAP
LEGEND
--('D--PRIMARY PAVED UNDIVIDED HIGHWAY
---SECONDARY PAVED UNDIVIDED HIGHWAY
-----SECONDARY GRAVEL. HIGHWAY
_..._........_ RAILROAD
-···-RIVER
0:....~~20i;;;;;iiii~4·0 MILES SCALE c
FIGURE 1.1 '
~ §
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/
N 3,225.000
-----'2.~0
(~
'i>.p
__/
N 3,226,000
N 3,227,000
N 3,228,000 I
I
/
N 3,229.000
~\ GALLERY ACCESS
I =-,::.=..,~ TUNNEL
"
. \ ~
\
\
\
\
\
\
\ CREST OF DAM
EL. 2210--------. . .
... / . ~
\\t------
1
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~--------~~---~~----~~~==--~~~~~~~~~--
I
WATANA
GENERAL ARRhNGEMENT
I
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0
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FIGURE 1.2
~
8
i w
EL 870
COFFERDAM
0 8 g 0 ..
" " w w
~ w w
1500
1550
1650
SCAL_E
0 200 400 FEET ~~
FIGURE 1.3
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2 -SUMMARY AND CONCLUSIONS
2.1-Introduction
The following subsections present the main findings and conclusions of
the 1980-81 geotechnical study for the Watana and Devil Canyon sites.
2.2 -Watana Site
(a) Results of Study
-Bedrock at the damsite is a large granitic pluton consisting of
a quartz diorite, diorite and granodiorite. An andesite por-
phyry, an extrusive volcanic rock, is exposed immediately down-
stream from the damsite.
-Where mapped and drilled, the contact between the diorite and
andesite is generally a highly fractured, weathered, poor qual-
ity rock. The contact zone ranges from 2 to 15 feet, but is gen-
erally less than 10 feet.
-Two major and two minor joint sets were mapped at the damsite.
These are in the order of most to least pronounced: (a) strike
320°, dip near vertical; (b) strike 045°-080°, dip near verti-
cal; (c) strike 340°-030°, with dips between 40° east to 65°
west; and (d) strike 080° with low angles of dip.
-Two pronounced sheared and highly fractured zones named "The
Fins" and "Fingerbuster" have been mapped immediately upstream
and downstream from the damsite.
-Small localized fractured, sheared, and altered zones have been
mapped within the damsite. These zones average up to 10 feet
wide. No evidence of recent faulting was found.
- A large altered and sheared zone up to 300 feet wide was mapped
on the upper left abutment of the main dam.
-The r-iverbed is filled with alluvium consisting of gravels,
cobbles, and boulders in a matrix of sand and silty sand ranging
from 40 to 80 feet, and may exceed 100 feet in depth in places.
Overburden thickness at the damsite is generally shallow ranging
from 50 to 60 feet on the upper abutment to 0 on the steeper
rock slopes. Overburden generally consists of glacially derived
silts, sands, and boulders and talus.
2-1
-Rock quality at the damsite is good to excellent with average
rock quality designations (RQDs) ranging from 75 to 90 percent.
Below the upper 20 to 40 feet of weathered rock, rock quality
tends to improve.
Rock strengths are high with an average unconfined cornpressi ve
strength greater than 20,000 psi.
The rock ma6s has, in general, a low permeability with an aver-
age of 10-em/sec below the weathered zones. Higher perm-
eabilities are found in the more highly fractured and sheared
zones.
-Groundwater at the damsite is a subdued replica of the topo-
graphy. Groundwater table on the right abutment is deep, on the
average of 110 to 280 feet. Groundwater conditions on the left
abutment are cornpl icated by the apparent deep and continuous
permafrost. A perched groundwater table exists on top of the
permafrost. Artesian conditions were encountered at depth on
this abutment within the thick alteration zone beneath the perm-
afrost.
-Permafrost appears to be cant i nuous in the bedrock throughout
the left abutment, reaching a depth of 200 to 300 feet. Al-
though no permafrost was encountered on the right abutment,
localized sporadic permafrost may be present.
-A relict channel exists on the right abutment extending from
Deadman Creek to Tsusena Creek. The thalweg reaches Elevation
1,800 (400 feet below maximum pool elevation). The width of the
relict channel at the upstream face is about 15,000 feet. In-
vestigations in and adjacent to the channel show that it is
filled with a sequence of alluvial materials overlain by a se-
quence of glaciofluvial silts, sands and clays. The average
hydraulic gradient through the channel at maximum reservoir
level is estimated to be approximately· 10 percent. The perme-
abilities within the channel are variable with high permeabili-
ties in the coarser bouldery strata and lower permeabilities in
the river silts, clays, and lacustrine deposits. Perched water
tables, aquicludes and localized permafrost exist throughout the
channel.
Bedrock surface drops below the maximum pool elevation on the
left bank approximately 2 miles upstream from the damsite in the
area of Fog Lakes. Based on seismic velocity measurements, bed-
rock was estimaed to be below reservoir level over a distance of
approximately 9,500 feet. The nearest drainage from this area
is Fog Creek, a distance of 5 miles southwest from the reser-
voir.
2-2
'.
-
-'
-[!
(b)
-The riverbed is filled with alluvium consisting of gravels, cob-
bles, and boulders in a matrix of sand and silty sand ranging
from 40 to 80 feet, and may exceed 100 feet ·in depth in places.
-Ten potential borrow and quarry sites were identified for poten-
tial construction material. Several of these sites, which had
been delineated in previous studies, were eliminated from fur-
ther consideration because of lengthy haul distances, more
locally available material, or insufficient volume. Those sites
considered as primary borrow and quarry sources are:
• Rock fill -Quarry Site A;
• Impervious and semi-pervious material -Borrow Sites D and H;
• Pervious material -Borrow Sites E and I; and
• Construction gravel and fill -Borrow Site F.
Areas of existing and potential slope instability and erosion,
as well as areas of permafrost were delineated within the Watana
reservoir.
Conclusions
Based on these findings, the following conclusions regarding the
Watana site can be made:
-No geologic or geotechnical conditions were found to affect the
feasibility of an embankment dam at the site.
-The significant geologic features "The Fins" and "Fingerbuster"
are considered unsuitab 1 e rock for construction of surface and
underground facilities and should be avoided if at all pos-
sible.
-Subsurface exploration at the damsite shows that rock quality on
the right abutment is suitable for the construction of large
underground facilities. Localized sheared, fractured, and
altered zones are 1 ike ly to be encountered during underground
excavation; however, it is considered that these features are of
limited extent and could be handled by conventional construction
procedures.
-There is an a 1 tered and fractured zone on the 1 eft abutment
downstream from the main dam. Any structure sited on this zone
would incur high costs for excavation and treatment.
-Although localized zones of sheared and fractured rock were en-
countered in all borings, no evidence of major faulting was
found in either the riverbed or within the damsite area.
2-3
-Further investigations of the material within the relict channel
will be required to accurately define its properties, strati-
graphy, permeabi 1 ity, and extent of permafrost for the purpose
of assessing potential reservoir seepage and behavior under
earthquake conditions.
-Suitable types and adequate amounts of borrow and quarry materi-
al were found near the damsite.
-Although local slumps and landslides will probably occur in many
areas of the reservoir, there appear to be no potentially large
landslides which might pose a threat to the dam.
2.3 -Devil Canyon
(a) Results of Study
The following geologic and geotechnical conditions have been iden-
tified at the Devil Canyon site:
-The proposed damsite is underlain by a metamorphic argillite and
graywacke rock.
The bedrock has been intruded by a series of mafic and felsic
dikes which crosscut the damsite. The contacts of the dikes
with the host rock are welded with some secondary localized
shearing or fracturing occurring at or near the contact.
-Two major and two minor joint sets have been mapped in the dam-
site area. These are, in the order of most to least pronounced:
(a) strike 340°, dip near vertical; (b) strike 020° to 100°, dip
from 55° southeast to 75° north; (c) strike 060° to 080°, dip to
northwest; and (d) strike northeast to east with low angle dips.
Average joint spacing for the most prominent set is 1.5 to 2
feet.
Localized sheared and fractured zones ranging from 1 to 3 feet
wide have been mapped at the damsite.
A highly sheared and fractured zone was found to parallel the
river beneath the proposed saddle dam on the left abutment. A
boring through this feature encountered breccia and gouge up to
3 feet wide. The east-west extent of this feature could not be
accurately determined; however, based on surface topography, it
is estimated to be no greater than 1,500 feet long.
-Stress relief joints were mapped up to 100 feet back from the
damsite gorge walls on the left abutment.
2-4
,.,
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'
-A marked drop off in bedrock elevation was noted in previous in-
vestigations along the eastern portion of Borrow Site G approxi-
mately 1,000 feet upstream from the damsite. Land access res-
trictions imposed during this study prohibited any further in-
vestigation at this feature. Work, however, performed in proxi-
mity to this area showed no compelling evidence for this feature
to be a fault.
-Minor fractures and shear zones were encountered in several of
the boreholes in the river; however, these were limited in ex-
tent and could not be correlated between borings. No indication
was found of faulting beneath the river or of recent faulting
anywhere at the damsite.
-Rock quality at the damsite was good to excellent with an over-
all RQD greater than 80 percent.
Rock strengths are high, averaging approximately 20,000 psi.
-Roc~ permeabil it i es are 1 ow, rang·i ng from 1 x 1o-4 to 1 x
10-em/sec with the lower permeabilities occurring in the
more highly fractured and sheared zones.
Based on preliminary data, groundwater levels appear to be vari-
able across the site, principally controlled by the degree of
fracturing within the rock mass. Readings in boreholes and pie-
zometers show water levels range from near surface above the
break in slope to as deep as 120 feet on the north abutment.
-No permafrost was found in the main damsite area.
-Borrow Site G, located approximately 1,000 feet upstream from
the damsite, has been identified as the principal source for
concrete aggregate and fill material. Quarry SiteK, located on
the left bank downstream from the damsite, has been identified
as the principal source for rockfill; and Borrow SiteD, adja-
cent to the Watana site, has been identified as the principal
source for impervious and semi-pervious material.
(b) Conclusions
Based on these findings, the following conclusions have been made
regarding the Devil Canyon site:
No geologic or geotechnical conditions were found at the Devil
Canyon damsite that would adversely affect feasibility for the
construction of a concrete arch dam.
2-5
-Rock quality was considered suitable for the construction of
underground power facilities, including a powerhouse and related
structures.
-Localized sheared and fractured rock is likely to be encountered
during underground excavation; it is considered that these fea-
tures are of limited extent and could be handled by conventional
construction procedures.
-Suitable types and quantities of borrow material have been iden-
tified for this study for dam con·struct ion.
The abrupt drop-off in bedrock east of the damsite beneath Bor-
row Site G, as well as the shear and fracture zones beneath the
saddle dams, will require additional investigation in subsequent
phases of study. However, these features are not expected to
have an impact on site feasibility.
-Although no permafrost was found during explorations, sporadic
permafrost may exist at the site.
There are no known areas that could result in significant leak-
age or slope instability in the reservoir.
2-6
~.
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-
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-
-
-
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-
3 -REVIEW OF PREVIOUS INVESTIGATIONS
3.1 -Introduction
The development of the Susitna Hydroelectric Project has been studied
by several federal and private agencies in the last 30 years. However,
it was not until the late 1950s that any geotechnical investigations
were conducted.
Between June 1957 and August 1958, the USBR performed geologic mapping
and drilling investigations at the Devil Canyon site and limited geo-
logic mapping at the Watana site (51).
Subsequently, during the 1970s, the COE performed additional investiga~
tions at both sites. These included seismic refraction surveys at
Devil Canyon, and detailed geologic mapping, seismic refraction survey,
diamond and auger drilling, and material testing at the damsite and po-
tential borrow sites at Watana.
This report briefly discusses the findings of these investigations as
documented by the USBR and COE. These reports, which are identified in
the bibliography (Appendix A), are available from the Power Authority
and Acres for reference.
3.2 -Watana
The preliminary reconnaissance work by the USBR in the 1950s was ex-
panded during the 1970s by the COE investigations of the damsite,
reservoir, and potential borrow sites. The location and extent of the
investigations in the main dam area are shown in Figure 5.1. Detailed
investigations in the borrow sites are presented in Section 6.3.
In 1975, a total of 22,500 linear feet of seismic refraction surveys
was performed by Dames & Moore (12) for the COE in their initial feasi-
bility report. This was expanded by Shannon & Wilson (39) in 1978 with
an additional 47,665 feet of survey. This work served to support the
re~ults of the drilling and mapping programs (Figure 5.1).
During the 1978 season, the site was explored with 28 diamond and ro-
tary dr-ill holes (both vertical and inclined) ranging from 30 to 600
feet in length (Table 3.1). Six of the diamond drill holes were locat-
ed in the river bottom and reached a maximum of 520 feet into rock.
Five borings were drilled on the left abutment and six on the right,
reaching a maximum depth of 300 feet or an elevation of 1560. On the
right bank, eleven boreholes were located in what was identified as a
deep, relict channel to determine the thickness and characteristics of
the overburden, the depth of the water table, and the permafrost condi-
tions. These boreholes were also designed to obtain samples of poten-
tial borrow materials and to evaluate bedrock depth to control spillway
1 ocat ion.
3-1
A total of six potential quarry and borrow sites were identified for
construction material. Of these, four borrow sites were explored with
27 backhoed test pits and 24 auger borings (Tables 3.2 to 3.3). These
areas included Borrow SiteD on the right abutment, Borrow Site E lo-
cated approximately 15,000 feet downstream from the dam, and Borrow
Site F located on Tsusena Creek three miles upstream from its conflu-
ence with the Susitna River (Section 6.3).
Geologic mapping was conducted in the damsite area to delineate major
structural features.
A 1 imited 1 aboratory testing program was conducted on potential borrow
material from the various borrow sites to establish the indexes and
engineering charaeteri sti cs of the borrow materia 1 s. These tests in-
cluded determination of grain size distribution, permeability, triaxial
shear tests, Modified Proctor compaction tests, concrete aggregate
tests, and petrographic analyses (46,48).
The COE also installed a series of ten open-well piezometers and thir-
teen temperature-logging casings in boreholes.
3.3-Devil Canyon
The bulk of the previous geotechnical investigation for Devil Canyon
was performed by the USBR between June 1957 and August 1958 {51) as
shown in Figures 5.2 and 7.22. A total of 21 diamond drill borings
were drilled in the damsite area. Six holes, drilled to depth of 50 to
110 feet were located on the left abutment. Four holes were drilled
near the dam axis on the upper abutment to a maximum depth of 150 feet.
The remaining 12 boreholes were drilled along the riverbed (Table
3. 4) •
Fourteen test pits were dug in the alluvial fan and terrace deposits
immediately upstream from the dam axis (Table 3.5).
Four rock benches were excavated on the dam abutments to define rock
conditions.
Laboratory tests, including gradation determinations and petrographic
analysis, were conducted on samples of the borrow site materials to
determine their suitabi 1 ity for use as concrete aggregate. Representa-
tive rock samples from the abutments were examined petrographically to
determine mi nera 1 ogy and tested to determine compressive strength,
elasticity, absorption, and porosity of the foundation material.
During 1978, Shannon & Wilson (39), under COE contract, ran three seis-
mic refraction lines totalling 3,300 feet in the borrow site and along
the proposed saddle dam to expand the drilling information {Figures 5.2
and 7.22). This survey, along with sampling of the alluvial fan mater-
ial, was the only work COE performed at the site during their 1978-1979
investigation.
3-2
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1.
3.4 -Conclusions
The investigations conducted by the COE and USBR were the first detail-
ed efforts to establish the feasibility of the project. A brief sum-
mary of their investigation is stated below:
(a) Watana
Based on the COE work, the Watana site was found suitable for an
earthfilled dam. The following is a brief summary of the coE•s
findings and conclusions relative to the site geotechnical condi-
tions:
(1) The river valley is filled with alluvium consisting of
gravels, cobbles, and boulders in a matrix of sand or silty
sand ranging in depth from 40 to 80 feet thick, and may be
exceeding 100 feet in places. Overburden on the valley
slopes ranges from 0 to 60 feet thick with an average of 10
to 20 feet.
(2) Underlying bedrock is fresh, hard-to-very hard diorite, gran-
odiorite, and quartz diorite with local andesite porphyry
dikes and more widely scattered minor felsite dikes.
(3) Fractures are closely spaced on the surface becoming more
widely spaced with depth. Deep fractures are generally heal-
ed.
(4) The prominent jointing and shearing direction is northwest
trending with steep dips. Many fractures have thin clay
gouge seams and slickensides.
(5) No major fault or significant change in material was found
beneath the river.
(6) Andesite porphyry, an extrusive rock, was mapped slightly
downstream from the damsite on the left abutment. The con-
tact between this rock and the diorite was not defined.
(7) Two prominent shear zones named "The F·i ns 11 and 11 Fi ngerbuster 11
were mapped as exposures in the damsite area. Both of these
zones trend northwest with strikes from 300° to 320° and dip
between 70° to 90° southwest and northeast.
(8) A relict channel was found on the right abutment upstream
from the damsite. IV!aterial in the channel consists of a mix-
ture of glacial tills, glaciofluvial and lacustrine deposits,
reaching a depth greater than 450 feet deep at its deepest
known point.
3-3
(9) Deep permafrost was found on the left abutment.
(10) Permafrost in the relict channel, although found within one
foot of the surf ace, is expected to be confined to a re 1 a-
tively shallow layer.
(11) Geology within the reservoir is complex and consists of vari-
able thicknesses of surficial tills; glaciofluvial outwash;
lacustrine material; and alluvium overlying igneous and meta-
morphic rocks, schists, volcanics, and granites.
(12) Potentially suitable borrow material was found near the dam
site. Material from Borrow Site D on the right abutment was
classified as semi-pervious to impervious core material.
Material from Borrow Site E from the alluvial deposit down-
stream from the dam axis was identified as a potential source
for clean aggregate and filter material.
(13) Two potential quarry sites were identified as sources of
rockfill, riprap, and coarse filter materials. The rock in
both sites was classified as diorite and of good quality.
(b) Devil Canyon
The previous investigations suggested that the Devil Canyon site
would be feasible for the construction of a high concrete gravity
or thin arch dam with an underground powerhouse. A brief summary
of the geotechnical conditions found by the USBR and COE are high-
1 i ghted be 1 ow.
(1) Bedrock at the site is an argillite with occasional beds of
graywacke. The rock is hard and brittle and contains numer-
ous quartz stringers.
(2) Stratigraphy strikes approximately east-west with a dip of
45° to 75° south. Three joint sets were defined with the
master set striking approximately 335° and dipping from 75°
east to vertical. Joint spacing ranges about 4 to 5 feet
apart.
(3) Several well-developed shears or fault zones occur on both
sides of the river and strike generally 335° and dip 80°
northeast to vertical.
(4) No permafrost was found at the damsite.
(5) Shearing was found both normal and parallel to the canyon rim
on the south abutment.
(6) Large detached blocks of rock up to 25 feet by 50 feet were
observed on the left abutment.
3-4
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(7) A deep, buried channel was found striking approximately east-
west beneath the 1 ake-fi 11 ed depression on the south abut-
ment. This depression may be underlain by a fault or shear
zone.
(8) River alluvium and water depth appears to be approximately 85
feet deep at the site.
(9) No faulting was found beneath the river.
(10) Rock conditions were considered suitable for underground ex-
cavations.
(11) The alluvial fan upstream from the site was found to contain
acceptable borrow material for concrete aggregate.
(12) Seismic refraction shows an unexplained steep slope of the
bedrock surface beneath the alluvial fan. This drop-off
occurs over a horizontal distance of approximately 500 feet.
This depth to bedrock increases (from west to east) from 100
feet to 350 feet.
3-5
..... , ] .. 'l
TABLE 3.1: SUMMARY OF PREV10115 lNVESUGAHGNS -WATANA DAMSITE
Total Dep't'h .to ·herm1stor :t'lezomet·er
Hole Surface Di) Azimuth· Depth (ft) Hedrock (ft) Date ' Water Level
Number .Elevation C". C") (Downhole) (Downhcii·e ) Drilled Type Reading 'Dates Ty:pe Reading Dates ' (Vertical}{ft)
DH-1 1458.6 u 122.'8 ·43~B 3/2£1/78
DH-2 1461.4 '0 29.'0 3/;23/78
DH-3 14.56.5 'I 0 174.5 77/.£, 4/3/7'8
DH-4 1462.4 '0 122.9 77.7 4/f7/J8
DH-5 1462.3 :o '176.9 59.4.6 :4/TB/78
DH-6 1115.5 0 149 .• 5 3~5 •4/28/VB
DH-J 1716 .• 0 59 21D 122,.2 B .• 5 5/'EJ/78
DH-8 1910.3 0 1'50.D 16.2 '5/21/78
DH-9 1913.0 '45 043 ~8:3.8 '5~6 5/38/78
DH-10 2033.2 D 283.'5 19.6 5/B!J'B
DH-11 2033.6 45 032 300.0 22 .• 7 5/22/7B
DH-12 195049 0 301.1 9.5 ·6/'11/78 T 7/11/78
B/10/18
71/30/80
DH-21 1478.3 57"'6 :003~·9 603.7 84.5 J/Jns T 11/29/78
DH-23 1951.5 :4·5 220 .. 3 119 .• 2 J .. o 7/7/JB 1 ''[ J/30/78
8/10/18
B/23/78
10/26/78
11/29/78
DH-24 2061..4 0 T3R.9 6.'9 7/251J'B T B/10/78
B/23/18
8/26/JB
11/30/78
J/30/80
12/~6/B1
DH-25 2044.9 44 047 79.9 B/8/'78 T 7/30/BD
DH-28 197!1.0 0 125.2 9.2 B/17/78 J 10/26/78
11/29/JB
DH ::: Dr ill hole
T = Thermistor pnibe -fluid-filleu standpipe
References (45) and (47)
. '} .. ~ .... l . 1 l
TABLE 3.2: SUMMARY OF PREVIOUS INVESTIGATIONS -BORROW SITE D -WATANA
lotal Depth to Therm1stor t'1ezometer
Hole Surface Depth ( ft) Bedrock ( ft) Date Readwg Read1ng l'!ater Level l ft l
Number Elevation (Downhole) (Downhole) Drilled Type Dates Type Dates (Vertical Depth)
1978 0.0 -2.0
AP1 2201.6 15.0 --6/15/78 SP 2/4/78 4.2
0.0
AP2 2199.0 11.0 --6/20/78 SP 1978 Frozen at 1. 2
AP3 2280.2 18.0 --6/20/78 2/4/82
AP4 2140.0 3.5 --6/21/78
AP5 2201.4 27.5 --6/21/78
AP6 2213.6 27.0 --6/21/78
AP7 2279.1 7.0 --6/21/78
AP8 2245.7 58.3 --6/23/78 T 1978
12/16/81
AP9 . 2295.8 18.0 --6/23/78 T 1978
12/16/81
AP10 2332.0 15.0 --6/23/78
AP11 2308.9 25.0 --6/28/78
AP12 2302.9 14.1 --6/28/78
AP13 2305.8 22.0 --6/28/78
AP14 2306.7 11.0 --6/28/78
AP15 2307.7 9.5 --6/28/78
AP16 2313.5 3.5 --6/13/78
AP17 2408.1 12.5 --6/13/78
AP18 2372.4 16.0 --6/13/78
AP19 2375.1 19.3 --6/13/78
AP20 2353.5 17.0 --6/15/78
AP21 2339.8 19.3 --6/15/78
AP22 2307.1 13.4 --6/13/78
AP23 2267.5 9.5 --6/15/78
AP24 2265.9 15.0 --6/15/78
TP8 2292.0 7.0 --8/16/78
TP9 2343.0 10.0 --8/15/78
TP10 2326.0 10.6 --8/21/78
TP11 2270.0 8.2 --8/18/78
TP12 2334.0 13.5 --8/21/78
TP13 2330.0 10.0 --8/22/78
TP14 2286.0 3.0 --8/17/78
TP15 2233.0 7.0 --8/19/78
TP16 2255.0 10.5 --8/16/78
TP17 2247.0 7.0 --8/18/78
TP18 2211.0 13.7 --8/19/78
TP19 2302.0 13.7 --8/21/78
TP20 2265.0 13.2 --8/21/78
TP21 2229.0 12.0 --8/23/78
TABLE 3.2 (Cont'd)
Hole Surface
Number Elevation
DR13 2321.4
DR14 2339.6
DR15 2294.0
DR16 2099.4
DR17 2167.0
DR18 2172.0
DR19 2151.4
DR20 2207.3
DR22 2229.1
DR26 2294.7
DR27 2321.6
AP = Auger probe
TP = Test pit
DR = Rotary drilled hole
SP -Standpipe
References (45) and (47)
Iota! Depth to
Depth ( ft) Bedrock ( ft) Date
(Downhole) (Downhole) Drilled
84.0 --4/17/78
75.0 --4/25/78
316.5 286.0 4/27/78
91.5 67.0 5/31/78
35.7 9.0 6/6/78
248.3 231.0 6/9/78
78.3 55.0 6/29/78
252.6 210.0 5/17/78
493.6 454.0 7/5/78
94.8 --8/9/78
44.0 --8/13/78
Thermistor t'1ezometer
Reading Reading Water Level \ ft!
Type Dates Type Dates (Vertical Depth)
T 12/16/71 1978 18.0 -30.0
1/4/82
1978 0.0 -10.0
1978 0.0 -5.0
2/4/82 14.2
T 7/30/80 SP 1978 4.0 -20.0
12/16/81 2/4/82 38.4
2/4/82
T 7/30/80 SP 1978 2.0 -6.0
12/16/81 2/4/82 13.6
2/4/82
SP 1978 27.0 -40.0
2/4/82 72.7
T 19.78 SP 1978 195.0 -200.0
7/30/80
12/16/81 '
2/4/82 2/4/82 '213. 0
T 1978 SP 1978 0.0 -13.0
12/15/81 2/4/82 23.7
2/4/82
·~
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1
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-I
Hole
Number
Borrow Site E:
TP1
TP2
TP3
TP3A
TP4
TP5
Borrow Site F:
TP6
TP22
TP23
TP24
TP25
TP26
Borrow Site C:
TP7
TP = Test Pit
TABLE 3.3: SUMMARY OF PREVIOUS INVESTIGATIONS -
BORROW SITES E, F & C -WATANA
Total Depth to
Surface Depth (ft) Bedrock ( ft)
Elevation (Downhole) (Downhole)
1420.0 8.0 --
1415.0 9.2 --
1435.0 5.0 --
1436.0 5.2 --
1442.0 9.2 --
1455.0 8.2 --
2110.0 5.7 --
2174.0 13.0 --
2160.0 14.0 --
2245.0 6.6 --
2190.0 7.4 --2232.0 13.5 --
2390.0 4.0 --
References (45) and (47)
Date
Excavated
6/21/78
6/24/78
9/25/78
7/25/78
7/26/78
7/28/78
6/29/78
8/24/78
8/25/78
8/25/78
8/25/78
B/25/78
6/23/78
TABLE 3.4: SUMMARY OF PREVIOUS INVESTIGATIONS -DEVIL CANYON DAMSITE
Total Depth to
Hole Surface Depth ( ft) Bedrock ( ft) Date
Number Elevation Dip ( o) Asimuth ( 0) (downhole) (Downhole) Drilled
DAMSITE:
DH-1 1419.7 45 157.5 117.3 0.0 6/4/57
DH-3 1381.1 0 --Trenched ----
DH-4 1375.7 0 --52.5 24.7 9/10/57
DH-5 1373.9 0 --86.2 55.5 7/25/57
DH-6 1370. 1 0 --107.3 86.9 8/10/57
DH-7 1376.6 0 --59.5 33.9 8/27/57
DH-8 1446.7 30 351 150.4 0.0 6/20/57
DH-9 1424.1 45 360 87.0 0.0 7/8/57
DH-10 1425.1 52 065 121.7 0.0 7/13/57
DH-11 893.5 42 355 30.5 0.0 7/30/57
DH-11A 893.5 45 355 29.1 0.0 8/4/57
DH-11B 893.5 51 355 33.9 0.0 8/8/57
DH-11C 892.7 57 355 150.1 0.0 8/13/57
DH-12 --60 045 127.5 0.0 9/16/57
DH-12A 896.0 45 045 149.3 o.o 10/1/57
DH-13 912.3 45 162 137 .o 0.0 7/22/57
DH-13A 912.0 37 162 80.7 0.0 8/2/58
DH-14 903.1 45 225 50.0 0.0 6/5/58
DH-14A 903.0 53 225 130.4 0.0 6/10/58
DH-14B 901.5 60 225 146.2 0.0 6/12/58
DH-14C 902.8 55 171 82.0 0.0 6/25/58
DH-15 1329.1 0 --68.3 47.6 9/24/57
51 1340.0 --------1958
52 1230.0 --------1958
53 1315.0 ------0.0 1958
54 1060.0 ------o.o 1958
References (28, 29 and 51)
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TABL~ 3.5: SUMMARY OF PREVIOUS INVESTIGATIONS -BORROW SITE G -DEVIL CANYON
Depth·to
Test Pit Surface Total Depth Bedrock Date
Number Elevation (Downhole) { ft:) (Downhole) ( ft) ~xcp.vated
TP6 --22.5 --1958
TP7 ------
TP17 --------
TP18 --------
TP19 --58.1 --1958
TP20 --------TP21 --30.0 --1958
TP22 --------
TP23 --------TP24 --------TP25 --------
TP26 --------
TP27 --------
TP93 --------
TP94 --15.0 --1958
NOT~S:
No data were available for TP7, TP17, TP18, TP20, TP27-TP27, and the two
unnumbered test pits,
References (28, 29, and 51)
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r
'
4 -REGIONAL GEOLOGY
4.1-Introduction
The Devil Canyon and Watana damsites lie in the Susitna River basin
within the Talkeetna Mountains of south-central Alaska. The regional
stratigraphy, structure, and glacial history are briefly discussed in
this s~ction. A more detailed discussion of specific regional tecton-
ics is presented in the Woodward-Clyde Consultants' report {58).
The geologic setting of the Talkeetna Mountains and the adjacent Susit-
na River basin has been interpreted as an enormous tectonic mosaic com-
posed of separate cant 1 nenta 1 structural blocks and fragments that
accreted to the North American plate during Mesozoic time (7,11,25,27,
38). The exact number of these blocks is unknown; however, geologic
and geophysical evidence suggest that the blocks moved northward a con-
siderable distance prior to collision with the North American plate
(22,33,42). This geologic history is reflected by the highly complex
structure and stratigraphy found throughout the region.
4.2-Stratigraphy
The oldest rocks Which outcrop in the region are a metamorphosed upper
Paleozoic (Table 4.1) rock sequence which trends northeastward along
the eastern portion ofthe Susitna River basin (Figure 4.1). These
rocks consist chiefly of coarse to fine grained clastic flows and tuffs
of basaltic to andesitic composition, locally containing marble inter-
beds (8). This system of rocks is unconformably overlain by Triassic
and Jurassic metavolcanic and sedimentary rocks. These rocks consist
of a shallow marine sequence of metabasalt flows, interbedded with
chert, argillite, marble, and volcaniclastic rocks. These are best
expressed in the project area around Watana and Portage Creeks. The
Paleozoic and lower Mesozoic rocks are intruded by Jurassic plutonic
rocks composed chiefly of granodiorite and quartz diorite. The Juras-
sic age intrusive rocks form a batholithic complex of the Talkeetna
Mountains (8).
The uplift of the Talkeetna Mountains and subsequent rapid erosion
associated with this plutonic event, resulted in the deposition of a
thick turbidite sequence of argillite and graywackes during the Creta-
ceous. These rocks underlie a large part of the project area and form
the bedrock at the Devil Canyon site {10). These rocks were subse-
quently deformed and intruded by a series of Tertiary age plutonic
rocks ranging in composition from granite to diorite in composition and
includes related felsic and mafic volcanic extrusive rocks. The Watana
site is underlain by one of these large plutonic bodies, which appears
to comprise the southern limit of the diorite pluton which predominates
along upper Tsusena Creek (6). These plutons were subsequently in-
truded and overlain by felsic and mafic volcanics. Mafic volcanics,
composed of andesite porphyry lie downstream from the Watana site.
4-1
4.3-Tectonic History
At least three major episodes of deformation are recognized (10) for
the project area:
- A period of intense metamorphism, plutonism, and uplift in the Juras-
sic;
-A similar orogeny during the middle to late Cretaceous; and
- A period of extensive uplift and denudation in the middle Tertiary to
Quaternary.
The first period (early to middle Jurassic) was the first major orogen-
ic event in the Susitna River basin as it now exists. It was charac-
terized by the intrusion of plutons and accompanied by crustal uplift
and regional metamorphism.
Most of the structural features in the region are the result of the
Cretaceous orogeny associated with the accretion of northwest drifting
continental blocks into the North American plate. This plate conver-
gence resulted in complex thrust faulting and folding which produced
the pronounced northeast/southwest structural grain across the region.
The argillite and graywacke beds in the Devil Canyon area were isoclin-
ally folded along northwest-trending folds during this orogeny. The
majority of the structural features, of which the Talkeetna Thrust
fault is the most prominent in the Talkeetna Mountains, are a conse-
quence of this orogeny. The Talkeetna Thurst is postulated as repre-
senting an old suture zone, involving the thrusting of Paleozoic, Tri-
assic and Jurassic rocks over the Cretaceous sedimentary rocks (10,11,
20,26,38). Other compressional structures related to this orogeny are
evident in the intense shear zones roughly parallel to and southeast of
the Talkeetna Thrust.
Tertiary deformations are evidenced by a complex system of normal,
oblique slip, and high-angle reverse faults. Two prominent tectonic
features of this period bracket the bas in area. The Dena 1 i fault, a
right-lateral, strike-slip fault 25 miles north of the Susitna River,
exhibits evidence of fault displacement during Cenozoic time (9). The
Castle Mountain-Caribou fault system, which borders the Talkeetna Moun-
tains approximately 70 miles southeast of the sites, is a normal fault
which has had fault displacement during the Holocene (18).
4.4 -Glacial History
A period of cyclic climatic cooling during the Quaternary resulted in
repeated glaciation of southern Alaska. Little information is avail-
able regarding the glacial history in the upper Susitna River basin.
Unlike the north side of the Alas.ka Range, which is characterized by
alpine type glaciation, the Susitna basin experienced coalescing pied-
mont glaciers from both the Alaska Range and the Talkeetna Mountains
that merged and filled the upper basin area.
4-2
-
-
-
....
At least three periods of glaciation have been delineated for the
region based on the glacial stratigraphy (30,34). During the most
recent period (late Wisconsinian), glaciers filled the adjoining low-
land basins and spread onto the continental shelf (30). Waning of the
ice masses from the Alaska Range and Talkeetna Mountains formed ice
barriers which blocked the drainage of glacial meltwater and produced
progl aci al 1 akes. As a consequence of this repeated gl aci at ion, the
Susitna and Copper River basins are covered by varying thicknesses of
tills and lacustrine deposits.
4-3
.....
-I
,.....
I
r
f"""
I
I
i
t~.
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r
r
ERA
Cenozoic
Mesozoic
Paleozoic
Precambrian
Reference (54)
TABLE 4.1: GEOLOGIC TIME SCALE
MILLION OF
PERIOD EPOCH GLACIATION YEARS AGO
Quaternary Holocene
Wisconsin ian
Pleistocene Illinoian
Kansan
Nebraskan 1 .B
Pliocene
Miocene
Tertiary Oligocene
Eocene
Paleocene 70
Cretaceous
Jurassic
Triassic 230
Permian
Pennsylvanian
Mississippian
Devonian
Silurian
Ordovician
Cambrian 600
T 32
T
32
N
T
31
N
T
30
N
Modified from Csej1ey,etol, 1978
LEGEND
CENOZOIC
QUATERNARY ,---,
> I .._ ___ ...~
n-;~IT=:J ~~/~1
fF"-rT1
I + T i
L... -4---"'-J
MESOZOIC
CRETACEOUS E-=:-=:-=-=-J ... _-_-_-_-_-J
t...-=------=--.J
JURASSIC
ITJill[O
UNDIFFERENTIATED SURFICIAL DEPOSITS
UNDIFFERENTIATED VOLCANIC AND
VOLCANICLASTIC ROCKS
GRANODIORITE, DIORITE
BIOTITE-HORNBLENDE GRANODIORITE,
BIOTITE GRANODIORITE
SCHIST, MIGMATITE, GRANITIC ROCKS
UNDIVIDED GRANITIC ROCKS
MAFIC INTRUSIVES
I ARGILLITE AND GRAYWACKE
'GRANODIORITE, QUARTZ DIORITE
REGIONAL G
1
LOGY
'7\ 7': 1\1\I'J
~6.6.6.~
TRIASSIC
r-ZA~ <N
~ :!_':_""_>j
PALEOZOIC
-
-T;_;H .. RUST FAULT . .... ..
AMPHIBOLITES, GREENSCHIST, FOLIATED DIORITE
BASALTIC METAVOLCANIC ROCKS, META BASALT
AND SLATE
BASALTIC TO ANDESITIC METAVOLCANICS LOCALLY
INTERBEDDED WITH MARBLE
TEETH ON UPTHROWN SIDE, DASHED WHERE INFERFlEol
DOTTED WHERE CONCEALED
INTENSE SHEARING POSSIBLE THRUST FAULT, TEETH ON UPTHROWN • • • '\1• • • • '\1 • • • SIDE
PROPOSED DAM SITES
0 4 8
SCALE IN MILES
FIGURE 4.1 m
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5 -SCOPE OF GEOTECHNICAL INVESTIGATION
5.1-Introduction
The overall geotechnical investigation program for the Watana and Devil
Canyon sites was designed to determine technical feasibility of the
sites for development of hydroelectric fac"ilities.
The principal objectives of the 1980-81 inv~stigation were to:
-Determine the suitability of the bedrock for excavating underground
structures which include penstocks, powerhouse, tailrace, and diver-
sion tunnels;
Determine foundation conditions in the damsite areas. Specifically,
to determine soil type and depth, thickness of weathered rock, rock
permeabi 1 ity, groundwater regime and extent of permafrost;
Define and investigate specific geologic structural features to in-
clude faults, shear and fractured zones, alteration zones, and
joints;
-Determine the availability of the required quantities of suitable
construction materials for the dams and related facilities; and
-Examine the stability of the reservoir slopes during filling and
operating the reservoir.
The scope developed to meet these objectives was based on:
-Discussions with individuals involved in previous studies;
-Detailed review of all previous data; and
-Information developed during the course of this study.
The engineering application of the data collected during this investi-
gation was applied to the design phase of the project in Task 6 and is
presented in the Feasibility Report (1).
The details of the program for each site are discussed in Sections 6
and 7.
5.2-Geologic Mapping
(a) Damsites
A geologic mapping program was undertaken to define the lithology
and structure of the damsites and reservoirs. All the geologic
data obtained in previous studies were used to supplement the data
collected during the 1980-81 program.
5-1
The Acres geologic mapping program was performed in three phases:
1980 summer, 1980/81 winter, and 1981 summer. The geologic map-
ping program for each phase was initiated by aerial reconnaissance
followed by a walking ground traverse.
The principal objective of the 1980 program was to perform general
reconnaissance mapping of the damsites and reservoirs to:
-Verify existing data;
-Locate potential borrow and quarry sources and refine limits and
and quantity estimates; and
-Identify areas that would require detailed mapping during the
next two phases of the program.
Data from the 1980 program were plotted on 1:6000 scale aerial
photographs. The mapping was performed by a team of two geo 1 a-
gists during the period of June through August.
The 1981 winter program was performed during the month of March
and consisted of mapping those areas along the Susitna River and
Tsusena and Cheechako Creeks that were not accessible during the
warmer months. However, poor ice conditions at Devil Canyon pre-
cluded mapping of several areas along the Susitna River. Particu-
lar attention was directed to mapping the extent and configuration
of "The Fins" and "Fingerbuster" at the Watana site. Similarly,
other sheared, fractured, and altered zones were mapped along the
river where access could not be gained during the summer months.
Mapping consisted of identifying each outcrop and noting its size,
orientation, weathering characteristics, lithology, and jointing,
as well as any other significant geologic feature. All signifi-
cant features were photographed.
The 1981 summer program entailed detailed mapping of both dam
abutments at Watana and Devil Canyon with particular attention
directed at defining the extent of any unusual geologic feature
denoted in the previous phases of the investigation. The extent
of the detailed mapping program is shown in Figures 6.3 and 7.3.
Mapping at Watana extended for approximately 3, 000 feet upstream
and 3,000 feet downstream from the proposed dam axis. Mapping was
performed in those areas having bedrock exposure. For the most
part, this was limited to the valley walls. Mapping at Devil Can-
yon extended for approximately 2,000 feet upstream and 2,500 feet
downstream from the proposed dam. Most of the mapping was con-
fined to the gorge walls, since very little outcrop exposure
exists beyond the break in slope. Mapping was performed by the
"tape and Brunton" method with key areas being marked for future
survey control. Mapping of the gorge wa 11 s was performed by geo-
logists trained as technical climbers.
5-2
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-
-
-
-
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-I ,,
All geologic data were plotted on a l-inch to 200-foot base map.
A detailed discussion of the results of the geologic mapping pro-
gram is presented in Sections 6 and 7.
(b) Reservoir Mapping
( i ) Genera 1
The Watana and Devil Canyon reservoirs were geologically
and geomorphically mapped to identify any geologic features
and geotechnical conditions which might seriously affect
the reservoir performance. Such features included buried
channels and faults in the reservoir rim which may jeopar-
dize the reservoir water tightness; faults which could be
activated by reservoir loading; and natural slopes which
may become unstable or erodible with reservoir fi 11 i ng or
drawdown.
Reservoir mapping consisted of airphoto interpretation per-
formed by R&M Consultants (Appendix J) and mapping of cur-
rent slope stability and permafrost (Appendix K). The
scope of these programs is discussed in the following sec-
tions.
(ii) Airphoto Interpretation
A terrain unit map was developed using a 1:24,000 airphoto
base map. Field checks of specific features were performed
as required. The interpretation identified 14 types of
land forms or individual terrain units. These are:
-bedrock -ablation till
-colluvium deposits -basal till
-landslide -outwash
-solifluction deposits -esker deposits
-granular alluvial fan -kame deposits
-floodplain -lacustrine deposits
-old terraces -organic deposits
Results of the airphoto interpretation are contained in
Appendix J.
(iii) Slope Stability
The potential for instability of the slopes within the
Watana and De vi 1 Canyon reservoirs after impoundment was
evaluated using color aerial photographs at a scale of
1:24,000, color infrared photographs at a scale of
1:120,000, and a brief field reconnaissance. Areas of cur-
rent slope instability, and the distribution of permafrost
were delineated. This information, in addition to the. soil
5-3
and rock conditions throughout the reservoirs, was used in
identifying the potential types and zones of instability
and erosion that could occur as a direct effect of the im-
pounding of the reservoirs. Details of this study are pre-
sented in Appendix K.
5.3-Subsurface Investigation
(a) Diamond Core Drilling
Diamond core drilling was performed on the abutments of both dam-
sites using a skid-mounted Longyear-34 diamond drill equipped with
triple tube wireline N-size core barrel. A total of approximately
8,000 linear feet of drilling was performed at Watana and 3,600
1 i near feet at Devi 1 Canyon. Seven di arnond core borings were
drilled at each site. All logging and supervision were by geolo-
gists. All rock core was logged for lithology, core recovery,
RQD, joints and fractures, shears, fracture zones and alteration
zones, and other significant geologic features. A discussion of
the results of the drilling program is presented in Sections 6 and
7 with Drilling Report and Summary Logs and perrneabil ity test
results contained in Appendices B through E.
A summary of the drilling activity for the 1980-81 field season is
shown in Tables 5.1 and 5.2 with drill hole locations shown in
Figures 5.1 and 5.2.
(b) In-Hole Testing
(i) Permeability Testing
Permeability testing was conducted in all the diamond drill
holes upon completion of the core drilling. Prior to test-
ing, each hole was thoroughly flushed with clear water and
the drill string withdrawn. Following flushing of the
hole, a packer assembly was lowered into the borehole to
the desired depth. The test procedure involved inflating
the packers with nitrogen to isolate a section of the bore-
hole, pumping water under pressure into the test zone, and
recording pressure and flow rates. Based on the flow
rates, hydraulic head, ho 1 e diameter, and 1 ength of test
section, the permeability of the rock in the test section
was ca 1 cul a ted. In genera 1, the packer assembly was in-
stalled to the bottom of the hole with tests being run over
16.1 foot intervals as the assembly was withdrawn.
The permeability for each test section was calculated using
the following formula:
k = 0.0679
5-4
_g_
~LH
L ln -r
-
,_
I
I
-
-
-
-
-
-
( i i )
Where k :::; permeability, em/sec
q :::; constant rate of flow, gpm
L :::; length of test section, feet
H :::; differential head of water, feet
r :::; radius of hole, feet
ln :::; natura 1 1 agar i thm
A maximum test pressure equal to 1 psi per foot of vertical
depth below the ground surface to the water table, plus 0.5
psi per foot of vertical depth below the water table down
to the test section was used. However, in no case was the
pressure allowed to exceed 200 psi. The actual gage pres-
sure was adjusted to take into consideration the depth of
water tab 1 e.
In order to obtain accurate permeability values, it was
necessary that the applied pressure and flow rates be mea-
sured accurately. A panel of four Fisher-Porter glass tube
variable flow meters was set up as shown in Appendix D.
These meters have an accuracy of 1 percent over full seale
and individual ranges of 0.021-0.267 gpm, 0.095-1.19 gpm,
0. 34-4.25 gpm and 0. 88-11.0 gpm. The pane 1 was set up to
use any of the four meters or to bypass them altogether.
Water pressure was supplied by a Royal Bean fixed-displace-
ment, piston pump. Test pressure was monitored using a
liquid-filled Ashcroft model 1279 pressure gage with a 0-to-
300-psi range and 2 psi divisions. The accuracy of this
gage is ~0.5 percent of full scale.
To eliminate pressure surging in the line to the gages, a
surge tank was installed and pressure snubbers were used
between the pressure gage and the main line.
Discussions of the results of the permeability tests are
presented in Section 6.1(f) and 7.1(f).
In-Hole Geophysical Logging
In-hole geophysical logging was carried out in three dia-
mond drill holes at the Devil Canyon site and two holes at
the Watana site. BH-2 at the Watana site caved badly and
was not tested. A total of 3,225 linear feet of logging
was completed. The logging procedure involved lowering a
geophysical probe in the hole on a wireline with the data
being returned to the surface and recorded on a self-con-
tained logging unit. The logs run in each hole included:
temperature, caliper, resistivity, and sonic velocity.
5-5
The purpose for the geophysical logging was to aid in in-
terpreting the subsurface conditions found at depth.
Because of poor data resolution, the results of the survey
have not been included in this report.
(iii) Instrumentation
To monitor the groundwater and permafrost conditions in the
bedrock, piezometers and thermistor strings were installed
in boreholes BH-3 and BH-6 at Watana (Figure 5.1); and
BH-1, BH-2, and BH-4 at Devil Canyon (Figure 5.2).
The piezometers used were a pneumatic type assembly manu-
factured by Petur Instrument Company of Seattle, Washing-
ton. The pneumatic type piezometers were selected because
subfreezing temperatures were likely to be encountered in
the upper portions of the holes which would cause blockage
in conventional standpipe piezometers. Pneumatic type pie-
zometers are also quick to install and easy to read.
The thermistor strings were manufactured by Instrumentation
Services in Fairbanks, Alaska. The thermistor strings were
each 250 feet long with thermistor points attached at 3, 6,
9, 12, 15, 18, 21, 25, 50, 75, 100, 125, 150, 175, 200, and
250 feet. A 40-strand cable was used to connect the therm-
istors to the surface, where a quick connect plug on the
cable was plugged into a switch box which in turn was con-
nected to a portable readout box. The system is designed
to obtain two readings at each depth so readings can be
cross checked. Each thermistor point was initially cali-
brated in the laboratory before installation and a computer
program set up to convert readings to temperature, taking
into account the correction factors for each thermi star.
An accuracy of 0.05°C was obtained with this equipment.
The installation details of piezometers and thermistors are
shown in Figures 5.3 and 5.4.
5.4 -Seismic Refraction Surveys
Seismic refraction surveys were performed at both damsites during the
1980 and 1981 field seasons. This survey data was used in conjunction
with borehole data, geologic mapping, and previous geophysical surveys
to define:
-Depth to bedrock;
-Bedrock seismic velocities;
-Extent of possible shear and fracture zones;
-Location and configuration of relict channels, and;
-Location and extent of potential borrow material.
5-6
~'
-'
-(
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-I
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-
-
-
A total of approximately 100,000 linear feet of seismic lines were per-
formed for this program with the results presented in Appendices H and
I. The location of the seismic lines in the damsite areas are shown in
Figure 5.1 for Watana and Figure 5.2 for Devil Canyon. Discussion of
the seismic lines in the borrow sites are presented in Section 6.3 and
7.2 with locations being shown on individual borrow site figures.
Most of the surveys were performed using a 1,100-foot seismic line in-
crement with 10Q foot spacing between geophones. Shorter geophone
spacing was used where terrain was rugged or overburden was shallow.
Explosive charges of 1 to 2 pounds were used as the energy source and
were placed at a distance of half the geophone spacing beyond the end
geophones and at the middle of the lines. For shorter lines, a hammer
and plate provided adequate energy. The seismic velocities were
recorded on a Geometries/Nimbus model ES-1210F 12-channel stacking
seismograph. A digital/analog converter was used to display the
results for data reduction.
At Watana darnsite, 5 traverses were run in the immediate damsite area,
10 traverses in the relict channel area, and 15 traverses in the borrow
sites.
At Devil Canyon, a total of four traverses were run in the immediate
vicinity of the small ponds on the left abutment. Land access restric-
tions prohibited any seismic work in Borrow Site G.
Details of the seismic survey are given in Table 5.2. The results have
been applied to the geologic and geotechnical interpretation of the
site presented in Sections 6 and 7.
5.5-Borrow Investigation
Test pits and auger holes were excavated and dri 11 ed in the proposed
borrow sites to determine their material properties, quantities and
extent.
Tab 1 es 5. 4 to 5. 8 provide a summary of the work in the borrow sites
performed during the 1980-81 field seasons.
The program initially used a platform-mounted CME-45 rig that was
replaced by aCME-55 because of the difficult drilling conditions.
Drilling was performed using a hollow-stem, continuous-flight auger
string, having an 8-inch O.D. and a 3-1/4 inch I.D., to a maximum depth
of 75 feet. Material samples were collected using a split-spoon samp-
1 er cant i nuously in the upper 10 feet of the hale and then at 5-foot
intervals to full depth. The sampling procedures consisted of drilling
the augers down to the required sampling depth, removing the inner plug
and stem, and advancing the split-spoon sampler 18 inches into the soil
below the cutting head by driving it with a 140-lb hammer falling free-
ly 30 inches (Standard Penetration Test). The samples were returned to
5-7
the surface, logged by a geologist, and prepared for transport and
storage. In most cases, 4-to 6-inch long, thin brass liners were used
inside the split-spoon sampler, which allowed selected samples to be
capped and sealed. Following completion of the hole, the auger string
was withdrawn and the hole backfilled with the drill cuttings.
Test pits were excavated utilizing a JD-350 dozer equipped with a back-
hoe. Average depth of the test pits ranged from 4 to 13 feet. Three
trenches were excavated along the edge of the alluvial fan in Borrow
Site G using the JD-350 (Figure 5.2).
Bulk samples from the holes and pits were collected and sealed in air
tight bags for subsequent laboratory testing.
The logs for the auger holes and test pits are presented in Appendices
F and G. The properties of the borrow materials are discussed in Sec-
tions 6.3 and 7.2.
5.6 -Laboratory Testing
(a) Soil
Representative soil samples obtained from the potential borrow
sites were tested to determine their physical properties and veri-
fy their field classification. Soil samples were .tested to deter-
mine grain-size distribution, moisture content, Atterberg limits,
moisture-density relationship, permeability values, consolidation
rates, and shear strength. All testing was done using ASTM or
AASHTO standard procedures where appl i cab 1 e. The results of the
testing program are summarized in Sections 6.3 and 7.2 with the
laboratory data included in Appendices F and G.
(b) Rock
Previous rock testing at the Watana and De vi 1 Canyon sites was
carried out by the USBR and COE. The results of this testing were
incorporated into the analysis of the rock conditions where appli-
cable.
The rock-testing program undertaken in 1980-81 was intended to
provide sufficient data to develop preliminary criteria for design
of underground structure excavations and foundations. Rock sam-
ples were selected for testing mainly to determine the range or
rock properties to be encountered at the site. Samples selected
included weathered rock, rock with discontinuities, and fresh rel-
atively homogeneous rock. Samples of low-strength rock, which
could not be recovered as solid core, were tested only for direct
shear tests on discontinuities. All samples were tested using the
appropriate ASTM standard procedures.
The scope of the 1980-81 rock testing program is shown in Tables
5.9 and 5.10, with the results presented in Sections 6.1 and 7.1.
5-8
~ .. -] .. ]
Hole Surface Dip Azimuth
Number Elevation c·) (0)
BH-1 2049.7 70 030
BH-2 1838.8 55 043
BH-3 2150.7 55 338
BH-4 2187.8 58 060
BH-6 1608.8 60 225
BH-8 1979.7 60 060
BH-12 1975.7 36 220
BH = Diamond core hole
PN = Pneumatic piezometer
MPT = Multi-point thermistor string
SP = Standpipe
Reference-Figure 5.1
] ·~ -1 ... ]
TABLE 5.1: SUMMARY OF 1980-81 INVESTIGATION -WATANA DAMSITE
Total Depth to Thermistor Piezometer
Depth ( ft) Bedrock (ft Date Wat.er Level
(Downhole) (Downhole) Drilled Type Reading Dates Type Reading Dates ( ft) Vertical
299.9 18.7 B/10/81
401.1 10.0 7/14/80
955.7 31.7 B/15/81 MPT 11/11/81 PN 9/1/81 0.0
12/9/81 11/11/81 0.0
1/5/82 1/5/82 0.0
949.6 12.4 9/11/81 SP 9/22/81 50.0
740.4 8.0 6/26/80 MPT 11/21/80 PN 11/21/80 147.0
4/26/81 5/24/81 126.2
5/24/81 6/25/81 103.2
6/25/81 12/9/81 115.0
8/3/81
12/9/81
752.4 8.0 7/29/80 SP 8/9/80 15.0
798.9 27.0 7/18/81 SP 7/28/81 0.0
l
Hole Surface Dip Azimuth
Number Elevation ( 0) (0)
BH-1 1413.7 67 225
BH-2 1213.4 60 0
BH-3 1398.0 32 058
BH-4 1352.6 60 195
BH-5A 974.5 45 189
BH-5B 976.6 45 277
BH-7 1351.0 45 009
BH = Diamond cored hole
MPT = Multi-point thermistor string
PN = Pneumatic piezometer
Reference -Figure 5.2
TABLE 5.2: SUMMARY OF 1980-81 INVESTIGATION -DEVIL CANYON DAMSITE
Total Depth to ,herm1stor
Depth ( ft) Bedrock ( ft Date
(Downhole) (Downhole) Drilled Type Readinq Dates
750.2 11 • 8 8/23/80 MPT 4/21/80
4/19/81
5/24/81
6/24/81
8/3/81
11/13/81
12/9/81
1/7/82
655.5 2.0 9/10/80 MPT 12/9/81
1/7/82
391.1 7.5 6/28/81
500.7 7.0 8/14/80 MPT 4/19/81
5/24/81
6/24/81
8/3/81
12/9/81
1/7/82
597.9 o.o 6/4/81
200.3 0.0 6/19/81
498.3 11.0 5/18/81
'1
_I
Type
PN
PN
PN
-~
J
P1ezometer
Readinq Dates
10/6/80
5/24/81
6/24/81
12/9/81
1/7/82
High
4/19/81
5/24/81
6/24/81
J
Water Tevel
( ft) Vertical
144.5
153.1
138.2
152.0
145.3
13.2
9.2
9.2
-
-
"""' !
-
r"'
I
-I
-
-
TABLE 5.3: SUMMARY OF 198D-B1 SEISMIC REFRACTION LINE DATA
WCC*
Line No.
80-1
80-2
80-3
80-4
80-5
80-6
80-7
80-8
80-9
80-10
80-11
80-12
80-13
80-14
80-15
81-1
81-2
81-3
81-4
81-5
81-6
81-7
81-8
81-9
81-10
81-11
81-12
81-13
81-14
81-15
81-16
81-17
81-18
81-19
81-20
81-21
81-22
81-FL-1
to
81-FL-48
R&M
Survey No.
80-1
80-2
80-3
80-6
80-7
80-8
80-9
80-11
80-12
80-13
80-15
81-1
81-2
81-3
81-4
81-5
81-6
81-7
81-8
81-9
81-10
81-11
81-12
81-1X
80-2X
BH-11
16-81
QSB
QSB
SW-1 X
B-12
17
L1ne
Length
(feet)
6,600
5,500
2,000
1 '100
2,200
2,200
1,100
2,200
1,120
1 '120
440
1, DOD
2,000
500
900
450
450
3,200
2,500
2,000
2,100
2,800
2,000
3,200
3,300
2,100
2,200
1,1 DO
2,200
1,1 DO
1,600
1,850
1,500
fog Lakes 28,800
Number of
Segments/Shots
8/31
5/19
4/11
2/5
2/10
2/110
1/3
4/13
3/8
3/8
1/2
1/3
2/6
1/2
1/3
1/3
1/2
3/9
3/6
2/6
2/6
3/9
2/7
3/10
3/5
4/11
2/8
1/5
2/10
1/6
5/11
5/19
3/6
48/138
Comments
Wat ana Rt Abutment-Relict Channel -
Extended NE by 81-13
Watana Rt Abutment-Relict Channel -
Extended NE by 81-13
Wat ana Abutments Upstream -81-6 Crosses
River in Middle
Not Used
Not Used
Watana Rt Abutment -"The Fins" Area
Watana Rt Abutment -Upper Relict Channel
Area
Quarry Source B Area -Extends SW-5 to South
Borrow Site E -Extends SW-14 to Northwest
Not Used
Borrow Site E -Adjacent to Tsusena Creek
Devil Canyon Saddle Dam Area
Devil Canyon Saddle Dam Area
Not Used
Devil Canyon Saddle Dam Area
Run Over River Ice, 2.1 Miles Upstream from
Wat ana Centerline
Run Over River Ice, 1.6 Miles Upstream from
Wat ana Crest
Run Over River Ice, 1.1 Miles Upstream from
Watana Crest
Run Over River Ice, 0.6 Mile Upstream from
Watana Crest
Run Over River Ice, 0.5 Mile Upstream from
Watana Crest
Run Over River Ice, 0.1 Mile Upstream from
Wat ana Crest
Run Over River Ice, 4.0 Miles Downstream
from Watana Crest
Run Over River Ice, 5.2 Miles Downstream
from Watana Crest
Run Over River Ice, 7.3 Miles Downstream
from Watana Crest
Run Over River Ice, 8.2 Miles Downstream
from Watana Crest
Run Over River Ice, 9.3 Miles Downstream
from Wat ana Crest
Run Over River Ice, 10.1 Miles Downstream
from Watana Crest
Relict Channel Area -Extends 80-1 to
Northwest
Relict Channel Area -Extends 80-2 to NE -
Northwest -North End Not Surveyed
Offset to Accommodate Topography
Watana Upper Relict Channel Area
Watana Upper Relict Channel Area -Not
Surveyed
Watana Upper Relict Channel Area -North of
Quarry Source B
Watana Upper Relict Channel Area -North of
Quarry Source B
Watana Left Abutment -Extends SW-1 East
Watana Left Abutment -Crosses 81-20
Devil Canyon Left Abutment -Crosses 80-12
and 80-13
Continuous Profile -Fog Lakes Area
*Profiles and time-distance plots included in (57)
Location reference-figures 5.1, 5.2, 6.38, 6.40, 6.43, and Appendices Hand I
g
TABLE 5.4: SUMMARY OF 1980-81 INVESTIGATION -BORROW SITE D -WATANA
Hole Surface
Number Elevation
AH-D1 2261.7
AH-D2 2335.3
AH-D3 2339.9
AH-D4 2255.0
AH-D5 2221.6
AH-D6 2262.9
AH-D7 2242.9
AH-D8 2276.1
AH-D9 2319.1
AH-D10 2357.8
AH-D11 2358.0
AH-D12 2337.9
AH-D13 2326.2
AH-D14 2272.7
W80-282
W80-300
AH = Auger hole
W = Grab sample
SP = Standpipe
Total Depth to
Depth ( ft) Bedrock ( ft)
(Downhole) (Downhole)
20.0 --
29.0 --
20.5 --
15.0 --
48.3 --
50.0 --
48.3 --
50.3 --
74.0 64.0
50.0 --
54.7 --
60.0 --
50.0 --
75.0 --
Grab
Grab
T = Thermistor probe -fluid-filled standpipe
Reference -Figure 6.40
] ~ ,, J '! j -)
Thermistor Piezometer
Date Keadlng Readmg l'!ater Level lfq
Drilled Type Dates Type Dates (Vertical Depth)
7/14/80
7/15/80
7/15/80
7/17/80
8/14/81 T 1/5/82 SP 2/4/82 9.0
2/4/82
8/22/81 T 1/5/82 SP
8/12/81 T 1/5/82 SP 2/4/82 Blocked at 29.0
2/4/82
8/9/81 T 1/5/82
7/25/81 T 1/5/82 SP
8/1/81 T 1/5/82 SP
7/27/81 T 1/5/82 SP
7/30/81 T 1/5/82
8/3/81 T SP
8/27/81 T 12/9/81 SP 2/3/82 10.0
1/4/82
2/3/82
1980
1980
1 'I l 3 ~ ~ 3 J
'1 ' ") _)
-
-
-'
-
Number
AH-E1
AH-E2
AH-E3
AH-E4
AH-E5
AH-E6
AH-E7
AH-E8
AH-E9
TP-E1
TP-E2
TP-E3
TP-E4
TP-E5
TP-E6
TP-E7
TP-E8
TP-E9
TP-E10A
TP-E10B
TP-E11
TP-E12
TP-E13
TP-E14
TP-E15
TP-E16
TP-E17
TP-E18
TP-E19
TP-E20
TP-E21
AH = Auger hole
TP = Test pit
TABLE 5.5: SUMMARY OF 1980-81 INVESTIGATION -
BORROW SITE E -WATANA
Total Depth to
Surface Depth (ft) Bedrock ( ft)
Elevation (Downhole) (Downhole)
1424.5 25.0 --
1463.3 10.0 --
1456.1 20.0 --
1443.7 20.0 --
1580.5 10.0 --
1436.8 26.5 --
1469.3 5.5 --
1504.0 6.0 --
1524.8 8.0 --
--10.0 --
1436.6 12.0 --
1464.2 13.0 --
1454.9 13.0 --
1470.1 10.0 --
1443.4 9.0 --1450.7 4.0 --
1450.2 12.0 --
1476.7 11.5 --
1500.7 13.0 --
1493.7 9.5 --
1512.7 12.0 --
1534.9 11.0 --
Not Dug ----
1503.0 10.5 --
1468.3 11.5 --
1463.8 11.5 --
1441.7 11.0 --
1455.1 12.5 --
1464.7 12.0 --1435.0 12.0 --
1425.4 12.0 --
Reference -Figure 6.43
Date
Drilled
7/1/80
7/18/80
7/3/80
7/17/80
6/23/80
7/19/80
7/20/80
7/21/80
7/20/80
4/19/81
4/18/81
4/17/81
4/18/81
4/16/81
4/15/81
4/15/81
4/20/81
4/21/81
4/22/81
4/22/81
4/24/81
4/25/81
--
4/26/81
4/28/81
4/30/81
5/1/81
5/2/81
5/2/81
5/3/81
5/3/81
TABLE 5.6: SUMMARY OF 1980-81 INVESTIGATION -BORROW SITE G -DEVIL CANYON
Hole Surface
Number Elevation
AH-G1 982.3
AH-G4 983.1
AH-G9 982.0
AH-G10 980.0
AH-G11 --
AH-G12 --
AH-G13 --
AH-G14 --
TT -G1 --
TT -G2 --
AH : Auger hole
TT : Test trench
Total Depth to
Depth ( ft) Bedrock ( ft)
(Downhole) (Downhole)
23.0 --
11.0 --
55.0 --
19.0 --
31.0 --
13.5 10.5
35.0 --
29 .o --
Trench --
Trench --
T : Thermistor probe -fluid-filled standpipe
Reference -Figure 7.22
_!hermistor
Date Reading
Drilled Type Dates
7/22/80 -- --
7/22/80 ----
8/22/81 ----
8/26/81 -- --
8/26/81 T None
B/27/81 T to
8/28/81 T Date
8/29/81 T --
7/21/81 ----
7/21/81 ----
-
r !
-
-
TABLE 5.7: SUMMARY OF 1980-81 INVESTIGATION -BORROW SITE H -WATANA
Total Depth to
Hole Surface Depth (ft) Bedrock ( ft)
Number Elevation (Downhole) (Downhole)
AH-H1 2127.5 26.5 23.0
AH-H2 1970.9 40.9 --
AH-H3 2079.6 29.0 --
AH-H4 2064.5 25.5 22.0
AH-H5 2186.2 35.5 --
AH-H6 2181.0 43.0 --
AH-H7 2188.4 30.7 25.7
AH-H8 2093.5 35.0 --
W80-256 --Grab --
W80-257 --Grab --
AH = Auger hole
T = Thermistor probe -fluid-filled standpipe
W = Grab sample
Reference -Figure 6.48
lhermistor
Date Keadlng
Drilled Type Dates
7/16/81 T 1/7/82
7/19/81 T 1/5/82
7/18/81 T 1/5/82
7/14/81 T --
7/13/81 T --
7/12/81 T --
7/15/81 T 1/7/82
7/17/81 T 1/7/82
-----
-----
Test Pit
Number
TP-R1
TP-R2
TP-R3
TP-R4
TP-R5
TP-R6
TP-R7
TP-R8
TP-R9
TP-R10
TP-R11
TP-R12
TP-R13
TP-R14
TP-R15
TP-R16
TP-R17
TP-R18
TP-R19
TP-R20
TP-R21
TP-R22
W80-302
TP = Test pit
W = Grab sample
TABLE 5.8: SUMMARY OF 1980-81 INVESTIGATION -
BORROW SITES I & J -WATANA
Iota! Uepth to
Surface Depth ( ft) Bedrock ( ft )
Elevation (Downhole) (Downhole)
--4.5 ----5.0 ----5.5 --
--4.5 --
--4.5 ----5.0 ----4.0 --
--2.5 --
--3.5 ----5.5 --
--4.0 ----5.0 --
--6.0 --
--6.0 --
--6.0 ----5.5 ----4.5 ----5.0 --
--4.0 ----5.0 ----4.5 --
--5.0 --
--Grab --
Reference -Figures 6.51 and 6.52
Date
Drilled
9/17/81
9/17/81
9/17/81
9/17/81
9/18/81
9/18/81
9/18/81
9/17/81
9/18/81
9/18/81
9/18/81
9/19/81
9/19/81
9/19/81
9/20/81
9/20/81
9/20/81
9/20/81
9/21/81
9/21/81
9/21/81
9/21/81
1980
~'
....
.... TABLE 5.9: SUMMARY OF ROCK TESTS -WATANA
No. of lests No. of Tests
Type of Test By Acres Standard by Others
Unconfined Uniaxial
Compression 29 ASTM D2938-71a ---Unconfined Uniaxial
Compression with
Stress/Strain Plot 4 ASTM D314B 6
Direct Shear 3 ----
Indirect Tension 11 ASTM C496 --
Point Load Test 303 ----
Specific Gravity 44 ASTM C97-47 (1970) 5 -Dynamic Modulus 2 ASTM D2845-69 (1976) --
-
-
--' '
!""'
I
I
TABLE 5.10: SUMMARY OF ROCK TESTS -DEVIL CANYON
No. of Tests No. of Tests
Type of Test By Acres Standard by Others
Direct Shear 6 ----
Indirect Tension 8 ASTM C496 --
Point Load Test 338 ---
Specific Gravity 40 ASTM C97-47 ( 1970) 6
Dynamic Modulus 3 ASTM D2845-69 ( 1970) 8
Unconfined Unaxial
Compression 26 ASTM D29 38-71 a --
Unconfined Unaxial
Compression with
Stress/Strain Plot 6 ASTM D3148 7
N3226.000
"sm.ooo
N3@2.000
N 3,234,000
"' 3:
<n
ID
3:
<n
N
REFERENCE' 1""200' COE,I978 WATANA DAMSITE TOPOGRAPHY, SHEET I THROUGH 26
CD
I
:::!i
0
l
§i
~! .....
l&Jl
i
i
·---~-· .....
..
I
3:
<n
CONTINU ES OFF
PAG E SEE NOTE 9
i
?
'·
I '-
' {~
/
/
~
*! ....I .... ;
."-./ (J
g! §.!
~ ~~ ... ,
"'' i
I
I I
DETAILED DAMSITE SEI SMIC LINE
AND BORI NG EXPLORATION MAP
SHOWN ON FIGURE 5.1 b
WATANA
al
~· ... I w'
l_ --~ 2200
--j
/
I
j
---'
_ _-·--~ I'....___ _/
~----./ ---
/
. l.r .1
DAMS ITE VICINITY -EXPLORATION MAP
-----
/
\
\
-------"""' -\ \
-, ""·'---1 \
I '....,,
\ \, \
"'· .. , ',
------------
LEGEND
0~~~4ioiiiiiiiiiiii~8 MILES
SCALE C
BOREH OL ES AND TEST PITS:
--0 DR-16 1978,COE ROTA RY DR ILL B ORING
GEO P HY SICAL SUR V E YS :
& SEISMIC REFR ACTIO N SURVEY END OR TU RNING POI NT
DM-C
SW-2
\., SLSI-5
1975, DA ME S 8 MOORE
1978, SHANNON 8 WILSON
1980-81, WOODWARD-CLYDE CONSULTANTS
'-I'
NOTES
I. DETAILED EXP L ORATION MAP OF DAMSIT E ON FIGURE 5.1b
2. BORR OW SITE 0 TEST PITS AND AUGER HOLES , AS WELL
AS SEISMIC L I NES, SH OWN ON F IGURE 6.40 .
3 . DETA IL ED SECTION ON OM -A 8 B ON FIGURE 6 .31.
4. RIVER ALLUVIUM T EST PITS SHOWN ON FIGURES 6 .51 AND 6 .52 .
5. RELICT CHANNEL AREA MAP S HOWN ON FIGURE 6 .35.
6. CONTOUR INTERVAL 100', ENLARGED AND TRACED FROM
REFERENCED BASE MAP
7 D 8 M SEISMIC LINE LOC ATION S CORRECTED PER CO E
SURVEY AND REFERENCED BASE MAPS.
8. S 8 W SE I SMIC LINE LOCATIONS COR RECTED FROM
ORIGINAL FIELD BOOKS AND S 8 W , 1978 .
9. LINE DM-B CONTINUED 11,000 FEET NORT H OF TURNING
POINT SHO WN .
10. COE EXPLORATION LOGS AND S 8 W SEISMIC PR OFILES
AS REFERENCED.
II. WCC SEISMIC REFRACTION DATA SHOW N IN APPENDICES
HAND!.
12. NORTH ING GRID LINES ARE IN ERROR BY APPROXIMAT ELY
50 FEET, NORTH, FROM STATION N 3, 232,000 TO
N 3, 234,000
S CALE 0~~~10~0;0;...;2~0-00 FEET
FIGURE 5.1 a
N 3,225,000 -
N 3,226,000 --
H 3,227,000
N 3,228,000
I
/ -TPR -8
N 3,229,000
,;
...
' a;
..J
(/)
/
/ ....___/ ..
~-
/
/
/
/
/
/
/
CONTI NUES OFF
PAGE SEE NOTE 2
.•.
~ "' ~
w
-. _,'
~/-
+
.~
...
/
/
/
/
/
' DR -19
----....
'
SW-1
. /
,.•
/
/'
d"DY-6,7
/
WATANA
EXPLORATION MAP
/~
g
! ~
W/
--. ._
FLOW
..... '
DH-28
:ill
':'
0
"' .J
(/)
---!)00 •'
550
600
;..
REFERENCE • BASE MAP FR OM COE,I978-I" • 200'
WAT AN A TOPOGRAPHY,SHEET 8 613
OF 26,COORDI NATES IN FEET, ALASKA
STATE PLANE (ZONE 4)
CO E , 1978
S 6W,I978
wee, 1980-81
CONTINUES OFF
PAGE SEE NOTE 2
//
/
:
!
/
-· / ~L:, ..
'1)-<:F PAGE SEE NOTE 2
,/
<V.,o ' ,_
/
SCAL E 0~~~20§0~--~4~00FEET
FIGURE 5 .1 b
1'43,221,000
REFERENCE : BASE MAP FROM R6M,I9BI-1"•200' DEVI L CA NYON TOPOGRAPHY
USBR, 1960
s 6 w, 1978
COE, 1978
COORDINATES IN FEET , ALASKA STATE PLANE (ZONE 4)
DEVIL CANYON
EXPLORATION MAP
/
I
/
/
\ ~/~ '
----------------------.....
-.....,
',
)
\ \
'1'3o
~'!S$o
':5ao
14:)0
1400
1300
12:)0
/1500
LEGEND
BOREHOLES AND TEST PITS:
q_DH ·I 4
BH-1
iX) A H ·GI
-TTK·I7
TP K-93
S -3
-TT-GI
1958, USBR 1 DIAMOND CORE BORING,HORIZONTAL
1980 _8 I,AAI PROJECTIONS AS SHOWN
1980-81,AAI AUGER BORING
1958, USBR DOZER TRENCH
HAND DUG TEST PIT
BLASTED ROCK SHELF
1981,AAI DOZ ER TRENCH
GEOPHYSICAL SURVEYS :
£!1 SW-1 5 SEISMIC REFRACTION SURVEY END
OR TURNING POINT
SW -1 5 1978, SHANNON 6 WILSON
SL80·13 1980-81, WOODWARD-CLYDE CONSULTANTS
NOTES
I. GEOLOGIC SECTIONS SHOWING EXPLORATION DETAILS
SHOWN ON FIGURES 7.4 THROUGH 7.10.
2.CO NTOU R INTERVAL so: TRACED FROM REFEREN CED BASE MAP.
3.U SBR EXPLORATIONS TRANSFERRED FROM USBR 1960
BY COORDINATES AND FROM USGS 1958 .
4.S 6 W SEISMIC LINE LOCATIONS CORRECTED FROM ORIGINAL
FIELD BOOKS AND S 6 W, 1978.
5.US8R ,COE EXPLORATION L OGS AND SEISMIC PROFILES AS
REFERENCED.
6 .AAI AND SELECTED USBR BORING LOGS SHOWN IN
APPENDIX C.
7. WCC SEISMI C REFRACTION LINES SHOW N IN APPENDICES
HAND I .
SCALE 0~~~2~0iii0iiiiiiiii~400 FEET
FIGURE 5 .2
-I
-
r
-
-
....
-
r
TO READOUT
L EGEI'lD
OVERBURDEN ///~/~~
ROCK \I,Jei,I,Jel.IA
PNEUMATIC
PIEZOMETER
TIP
END
PLUG
0.75 -INCH I.D. THREADED
JOINT PVC GROUT TUBE
THERMISTOR POINTS
PACKER INFLATION LINE
AND PIEZOMETER READOUT
TUBES
HOLES DRILLED IN~\
PVC GROUT TUBE
TO ALLOW GROUT
TO ESCAPE '"--NQ-BOREHOLE (2.98 INCH DIAM.}
CEMENT GROUT
EPOXY-FILLED NX-SIZE PACKER
SLOTTED PVC PIPE TO
PROTECT PIEZOMETER
TYPICAL BOREHOLE INSTRUMENTATION
WATANA: BH-6 AND BH-3
DEVIL CANYON: BH-2
(NOT TO SCALE}
PREPARED BY RaM CONSULTANTS, INC. FIGURE 5.3
-
r
-
-I
-
r
r
r
-
-
LEGEI'JD
OVERBURDEN 11~/S:I!~/1
ROCK ~IE!!IELIS.I.S.
NOTE
TWO PIEZOMETER/ PACKER
INSTALLATIONS WHERE MADE
IN BH-1
20-FOOT SLOTTED
SECTION. THREE ROWS
0.010-INCH SLOTS
0.5-INCH I.D.
GROUT TUBE
~
2-INCH I. D. THREADED _ ___., ,
JOINT PVC CASING
TO READOUT
NQ-BOREHOLE
(2.98 INCH
DIAM.)
THERMISTOR
POINTS
PACKER INFLATION LINE
AND PIEZOMETER READ-
OUT TUBES
PERMAFROST CEMENT GROUT
NX-SIZE SLlMLlNE PACKER
PNEUMATIC PIEZOMETER TIP
FILTER SAND
GROUT TUBE
5-FOOT SLOTTED SECTION.
THREE ROWS 0.10-INCH SLOTS
END
PLUG TYPICAL BOREHOLE INSTRUMENTATION
DEVIL CANYON: BH-1 AND BH-4
(NOT TO SCALE)
PREPARED BY RaM CONSULTANTS, INC. FIGURE 5.4
-
-'
-
,....
I
r
~-l
6 -RESULTS OF GEOTECHNICAL INVESTIGATIONS -WATANA
The results of the geotechnical studies performed at the Watana site
are presented in this section. The three principal subsections are:
-Subsection 6.1: Watana Damsite;
-Subsection 6.2: Relict Channels; and
Borrow & Quarry Material. -Subsection 6.3:
Map locations presented in this section are shown on the Watana Index
Map -Figure 6.1.
6.1 -Watana Damsite
(a) Overburden Conditions
( i )
(; i)
General
A top-of-bedrock and surficial geologic map for the damsite
area is shown on Figure 6.2. Determination of these over-
burden thicknesses and material types at the site has been
based on geological mapping, seismic refraction surveys,
drilling, and test pits. Geologic profiles depicting sub-
surface stratigraphy in the main dam area and borrow sites
are presented in later sections. Data used in developing
these figures are provided in Appendices B, F, H, and I
while Table 6.1 provides the correlation of seismic velo-
cities with soil and rock types used for this study.
Damsite
Within the limits of the damsite, three distinct zones of
overburden can be delineated at the site. These are: (a)
top of slope (elevation approximately 2200) to approximate
Elevation 1950 to 1900; (b) Elevation 1900 to river level,
and (c) riverbed.
The upper areas of the abutments near the top of slope con-
sist of deposits of till, alluvium, and talus. On the
north abutment, the alluvium is significantly intermixed
with talus material. The thickness of this cover may reach
50 to 60 feet. ·On the south abutment, the average overbur-
den depth is estimated at 20 feet with isolated zones of
apparent channel fill material reaching 70 feet or more, as
shown by seismic line SL81-20 and DH-25 (Figure 6.2).
Below Elevation 1900 to 1950 where the valley changes from a "U" shape to a "V" shape, the overburden becomes thinner
and more varied, ranging from probable maximums of 40 feet
thick at the river edge (where there are ta 1 us and minor
6-1
avalanche deposits) to zero along the numerous rock cliffs.
Most of the material is rock derived from the cliffs with
occasional remnants of silty sand and gravel river terrace
deposits. Some 1 arger, well-rounded boulders occur at the
lower elevations. The average abutment overburden thick-
ness in this zone is estimated to be 10 feet of alluvium
and loose talus materials.
Cobbles and gravels occur from flood elevation (about 1470
feet) down to the river. Boreholes and seismic lines in
the river show a relatively consistent deposit of river al-
luvium composed of gravel, cobbles, and boulders with a
sand matrix interspersed. The maximum depth of river allu-
vium in the main dam area is estimated not to exceed 90
feet.
A recent seismic refraction survey suggests that there are
bedrock shallows near the proposed upstream cofferdam site
(Appendix I). This interpretation is questionable because
of the poor resolution of the seismic data. A more reason-
able interpretation would be either the existence of frozen
material or the presence of very densely compacted tal us
material that has been eroded from the adjacent "The Fins"
structure (Section 6.1[c]). However, further work will be
required in this area to confirm these velocities.
(iii) Emergency Spillway
The upper portion of the proposed emergency spillway is
founded in an area of shallow overburden, whereas the west-
northwest extension of the spillway that extends downslope
off the flank of the pluton is in an area of deeper over-
burden. The estimated depth to rock in this area is shown
in Figure 6.2.
(iv) Camp Areas
The proposed construction camp and permanent vi 11 age site
is northwest of the damsite in an area of deep overburden
that consists primarily of sands and gravels with inter-
spersed boulders. Bedrock depths are expected to exceed
100 feet throughout the area. A more complete discussion
of the geology and overburden of this area is presented in
Section 6.2.
(v) Access Roads
Construction of access roads to the site wi 11 encounter
areas of very deep overburden. Access and haul roads out-
side the damsite area will, to some degree, be routed along
gravel terraces, but in many areas will cross shallow,
6-2
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boggy, and swampy areas and zones of till, c 1 ays, and
silts. Further detailed investigations will be required in
subsequent phases of study to accurately determine soil and
foundation conditions along proposed access routes.
(b) Lithology
(i) Introduction
( i i )
The Watana site is 1 ocated on the western side of a Ter-
tiary age (Table 4.1) igneous plutonic body which consists
primarily of diorite and quartz diorite (Section 4). This
pluton is bounded in the site area by andesitic volcanic
flows and volcaniclastic sedimentary rocks. These rocks
have not been assigned formational names, but rather have
been given lithologic names for mapping and correlation
purposes.
The lithology and structure at the Watana site are shown on
a geologic map, Figure 6.3, and five geologic sections, W-1
through W-5 (Figures 6.4 to 6.8).
The geology shown in these figures is based on field map-
ping, and borehole and seismic refraction data (Section 5).
Where possible, mapped surface structures were correlated
with subsurface drilling and seismic refraction data. How-
ever, the limited rock exposure and the widely spaced sub-
surface exploration data in the damsite frequently required
extrapolation of geologic contacts and structural features
over great distance. Therefore, future investigations will
be necessary to confirm the location and continuance of
those features shown in the figures.
For simplicity, borehole information shown on Figures 6.4
to 6.8 is limited to features five feet or greater in
thickness. More detailed information is contained in
Appendices B, D, H, and I.
The following subsections address the site lithology.
Plutonic Rocks
At the Watana site, the pluton is nearly continuously ex-
posed in large outcrops along the south bank between Ele-
vations 1650 and 1900. On the north bank, outcrops are
generally smaller and less frequent (Figure 6.2). The
rocks of the pluton are primarily diorite and quartz dio-
rite with lesser amounts of granodiorite. These varied
lithologies are probably the result of chemical variations
within the parent magma, primarily increasing silica con""
tent from diorite to granodiorite. The rock types are
6-3
observed in both outcrop and boreholes to grade from one to
the other. A 20-foot wide gradational contact between the
diorite and quartz diorite is exposed at river level on the
south bank approximately 1,000 feet upstream from the dam
centerline. A similar gradational contact is found in
boreholes BH-6 and BH-8 (Appendix B) over 0.3 foot at Ele-
vation 1594 and 3.8 feet at Elevation 1708, respectively.
Since no mappable pattern was found to differentiate these
three rock types, they have been combined on the geologic
map and sections under the general name of diorite.
The diorite here is described as a crystalline igneous rock
which is predominantly medium greenish gray but varies to
light gray and light to medium greenish gray in the grano-
diorite and quartz diorite phases, respectively. The tex-
ture is massive with no planar structures. Grain size var-
ies from fine (less than 1mm) to medium (1-5mm) but is
usually medium. The diorite is generally composed of 60 to
80 percent feldspar, 0 to 10 percent quartz, and 20 to 30
percent mafi cs.
Quartz content of the quartz diorite ranges up to 20 per-
cent but is usually 10 to 15 percent. The feldspar con-
sists primarily of medium grained, euhedral plagioclase
with minor amounts of fine grained anhedral orthoclase. In
the granodiorite, orthoclase content is about 10 percent.
Quartz, when present, is fine grained and i ntergrown be-
tween the feldspar crystals. Mafic minerals, consisting of
biotite and hornblende, are generally fine grained. The
hornblende is often partially chloritized. Trace amounts
of sulphides and carbonate also occur within the diorite.
Inclusions of argillite have been observed in the diorite
in "The Fins" area (Figure 6.3).
The diorite is generally fresh and hard to very hard. The
rock is slightly weathered along the joint surfaces at a
depths of about 50 to 80 feet (Section 6.1[c]). There is
generally a very thin (less than 2 inches) weathering rind
on most outcrops.
The pluton has been intruded by both mafic and felsic dikes
which are discussed below.
Zones of hydrothermal alteration occur within the diorite.
The alter at ion has caused the chemica 1 breakdown of the
feldspars and mafic minerals. The feldspars have altered
to kaolinite clay and the mafics altered to chlorite.
Hydrothermal alteration is discussed in detail in Section
6.1(c).
6-4
!fi"T'-·
( i i i)
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Andesite Porphyry
The name andesite porphyry is used for a varied group of
apparently related extrusive rock types {46). The andesite
porphyry occurs along the western side of the diorite plu-
ton and is exposed in outcrops on both sides of the Susitna
River (Figure 6. 3). On the south bank, outcrops occur
across from the "Fi ngerbuster 11 and at approximate Elevation
1750, immediately downstream from the dam centerline. And-
esite porphyry was drilled in boreholes BH-4 {Figure 6.4),
BH-8 {Figure 6.5), and BH-2 (Figure 6.7) to depths of 96.0,
43.0 and 103.0 feet, respectively. Borehole DH-28 bottomed
at 125 feet in the porphyry (Figure 6. 8). Andesite por-
phyry dikes are also found interspersed in the diorite. On
the north bank, the andesite is exposed at river 1 eve 1 in
the 11 Fi ngerbuster 11 area and in scattered outcrops to about
Elevation 2350.
The andesite porphyry is a 1 i ght to med i urn dark greenish
gray volcanic rock similar in composition to the diorite
pluton. The color becomes lighter with increasing amounts
of lithic inclusions. The groundmass is aphanitic (grains
visible only with the aid of a microscope) with generally
10 to 30 percent of fine to medi urn grained pl agi ocl ase
feldspar phenocrysts. Lithic inclusions are found through-
out the andesite porphyry but are most concentrated near
the contact with the diorite. Concentrations of subrounded
to subangul ar fragments, up to 6 inches in diameter, of
quartz diorite, argillite and volcanic rocks \'tere found
above the diorite contact in BH-8 (Appendix B). The ande-
site porphyry is fresh to slightly weathered and hard.
Hydrothermal alteration is not common in the andesite por-
phyry.
The andesite porphyry a 1 so contains 1 ayers or zones of
dacite and latite and basalt. The latite occurs in the
11 Fi ngerbuster 11 area ( 4 7) and the dacite in Quarry A. The
basalt occurs in the area of the volcaniclastic sediments
downstream from the 11 Fi ngerbuster. 11
These varied rock types appear to be irregular and discon-
tinuous in the site area and could not be mapped over large
areas. Therefore, the term andesite porphyry has been used
as a general term for all of these volcanic units.
Outcrops on the south bank near the diorite contact contain
from 30 to 50 percent lithic fragments in an andesite mat-
rix. Flow structures are visible in outcrops and boreholes
in the areas of abundant lithic fragments. On the south
6-5
bank, about 350 feet northeast of DH-28, the flow structure
strikes east-west and dips 20° to the south. In the "Fing-
erbuster" area, flow structures strike northwest-southeast
and dip 15° to the west. Figure 6.9 is a photograph of the
andesite porphyry in the "Fi ngerbuster" area which shows
numerous lithic inclusions, as well as flow structure line-
ation.
A sequence of volcaniclastic rocks (46) composed of tuf-
faceous sandstones and s i 1 tstones are exposed 2, 500 feet
downstream of the contact between the andesite porphyry and
the diorite. The siltstones are medium gray, fine grained
while the sandstone has a buff colored ground mass with
grains of feldspar, quartz and argillite. Bedding of these
units strike nearly north-south with dips generally 1 ess
than 30° to the west. The rock is s 1 i ght ly weathered and
iron oxide stained. The relationship between the volcani-
clastic rocks and the andesite porphyry is not clearly
defined because of outcrop exposure.
(iv) Contact Between Andesite Porphyry and Diorite
The contact between the andesite porphyry and the under-
lying diorite has been mapped immediately downstream from
the proposed dam centerline, extending in a general north-
westerly direction across the left abutment and northerly
across the right abutment (Figure 6.3). On the south bank
it is intersected in BH-8 and BH-12 and exposed in one out-
crop west of the dam centerline at about E 1 evat ion 1750.
At this point, between 400 to 800 feet northeast of DH-28,
the diorite is generally fresh to slightly weathered and
unfractured. The andesite porphyry is slightly to moder-
ately weathered and fractured up to 10 to 15 feet above the
contact. Figure 6.10 is a photograph showing the closely
to very closely spaced joints in the andesite porphyry
immediately above the diorite contact.
Where the contact is exposed on the south bank, minor
shearing, less than 1 inch wide, occurs between the ande-
site porphyry and the diorite. The contact in this area
strikes nearly east-west with a dip of 45° to the south.
In BH-8, the andesite porphyry/diorite contact is found at
a depth of 43.0 feet. From 38.4 to 43 feet, thin layers of
andesite porphyry are moderately to severely weathered with
layers of silty sand. Core loss in this zone was 1.1 feet
with only 50 percent dri 11 water return. The contact in
BH-12 was intersected at a depth of 63.7 feet. Unlike
BH-8, the andesite above the contact (from 54.8 to 63.7
feet) is fresh to moderately weathered with generally
closely to moderately closely spaced joints. The contact
occurs over a 3-inch-wide zone where the andesite porphyry
6-6
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(v)
interfingers with the diorite. The diorite is fresh below
the contact. Core recovery was generally 100 percent
through the contact zone with variable RQDs. Permeabilities
are on the order of 1o-5 em/sec.
On the north bank, the contact is not exposed but was in-
tersected in BH-2 and BH-4. In BH-4, very closely spaced
joints with silt and clay coating occur in the andesite
porphyry from 94.1 feet to the contact at 96 feet. As in
BH-12, very thin fingers of andesite porphyry penetrate the
diorite at the contact. The diorite below the contact is
slightly weathered with iron oxide staining in the upper
0.5 feet. RQDs are quite low, ranging from 0 to 51 percent
in the upper 15 feet of the diorite. Permeabil it i es, how-
ever, are 1 ow at about 10-6 em/sec. The contact from
river level (Elevation 1450) to about Elevation 2000 in
this area is coincident with a major shear zone ("Finger-
buster") (Section 6.l[c]). This zone, which was drilled in
BH-2, showed 1 ow RQDs and core 1 oss. This poor qua 1 ity
rock is the result of post-intrusion shearing of the "Fin-
gerbuster" and not necessarily representative of the con-
tact. Above Elevation 2000, the contact is assumed to dip
moderately to the northwest.
Dikes
The diorite pluton has been intruded by both mafic and fel-
sic dikes. No dikes were found in the andesite porphyry.
Because of their small size, the dikes could not be deline-
ated as mappable units.
Felsic dikes are found in outcrops and in all boreholes.
Felsic dikes are light gray and aphanitic to medium grain-
ed, but generally fine grained. The felsic dikes are com-
posed primarily of feldspar (plagioclase and orthoclase)
with up to 30 percent quartz and less than 10 percent maf-
ics. Contacts with the diorite are tight and "welded". The
felsic dikes are hard, fresh, and unfractured. Dike widths
are up to 6 feet but generally less than 0.5 feet. Felsic
dikes have been found offset up to sever a 1 inches by shears
and healed shears in outcrop and in boreholes (BH-3 at
702. 7 and 801.3 feet). Figure 6.11 shows a 7 -inch wide
felsic dike offset along a healed shear. The healed shear
is tight and hard.
Mafic dikes are less common at the site than the felsic
dikes. They are rarely seen in outcrop and only found in
boreholes BH-1, BH-2, BH-8, and BH-12. The mafic dikes,
consisting of andesite or diorite, are dark green to dark
green gray. Grain size is aphanitic to very fine, with
fine to medium grained plagioclase phenocrysts (BH-2,
6-7
Appendix B). The mafic dikes are hard and fresh with tight
contacts. Dike widths are generally less than 1 foot,
although in BH-2, an andesite dike was drilled from 245.8
to 277.8 feet. Diorite inclusions were also found in this
dike. A possible mafic dike was mapped on the south bank
at river level upstream from the centerline. This dike is
approximately 5 feet wide and consists of fine grained dio-
rite. The dike is very closely to closely jointed and
occurs in a talus-filled gully. The trend of the dike is
northwest-southeast parallel to a major joint set. As with
the felsic dike, the mafic dikes could not be mapped over
an extensive area.
A large mafic dike~ 350 to 400 feet wide, has intruded into
the diorite upstream from the proposed diversion tunnel in-
take portal. Outcrops occur in the "The Fins" on the north
bank and in Quarry L on the south bank (Figures 6. 3). The
dike is porphyritic with an aphanitic to fine grained
ground mass. Medium grained phenocrysts, consisting pri-
marily of plagioclase feldspar and lesser amounts of horn-
blende, comprise up to 10 percent of the rock in "The Fins"
and 20 to 30 percent on the south bank. The bedrock in
this area has been termed a diorite porphyry. The rock is
fresh hard and generally massive with rare occurrences of
compositional layering or possible flow structure. Inclu-
sions in this unit consist of rounded diorite and tabular
argillite fragments from 1 to 6 inches long. Contacts with
the inclusions are sharp and tight.
The diorite porphyry becomes less porphyritic and more
aphanitic near the contacts with the diorite pluton. The
western contact in "The Fins" is coincident with a 20-foot-
wide shear/alteration zone (see Section 6.l[c]). The eas-
tern contact is not exposed.
(c) Structural Geology
(i) Introduction
This section discusses the structural geology at the Watana
site and its relation to proposed site facilities. This
section is presented in three subsections: joints; shears,
fracture zones, and alteration zones; and significant geo-
logic features.
(ii) Joints
Joint data were recorded at all outcrops, as well as at
nine joint stations (WJ-1 through WJ-9) which were selected
for detailed joint measurements (Figure 6.12). Joint sta-
tions were chosen at representative areas having good
6-8
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three-dimensional exposure of major structures and in the
major rock types: diorite, andesite porphyry, and diorite
porphyry. At outcrop and joint stations, the orientations
of major and minor joint sets were recorded, as well as the
condition of the joint surfaces, spacing, and any minerali-
zation or coating.
At stations WJ-1 through WJ-3, only 60 to 86 joint readings
were taken because of limited exposure, while one hundred
joints each were recorded at each of the other six sta-
tions. For each station, joint measurements were plotted
on the lower hemisphere of a Schmidt equal-area stereonet
and contoured at 1, 3, 5, 7, 10, and 15 percent. An
example illustrating the plotting method (5) is presented
on Figure 6.12.
In addition to the joint station plots, composite joint
plots were constructed from bGth joint station and outcrop
data. The site was divided into four quadrants. A compos-
ite plot for each quadrant is shown in Figure 6.13.
Two major and two minor joint sets were mapped at the
Watana site and are identified on the composite and joint
station plots. Sets I and II are major sets which occur
throughout the site area. Sets III and IV are minor sets
which are generally less prominent but may be locally
strong. Each joint set is discussed below, while Table 6.2
is a summary of joint set orientations, dips, spacings,
surface conditions, and structural relations. The joint
sets are common to all rock types at the damsite.
This discussion is based on mapped surface jointing.
Because the orientations of joints and fractures in the
boreholes were not determined, it is not poss·ible to corre-
late between joints in outcrop and those encountered at
depth. Joints in boreholes are discussed separately.
\
Joint Set I is the most prominent set at Watana. The aver-
age orientation is 320° in the four quadrants (Figure
6.13). Dips average 80° northeast in the northeast and
southeast quadrants and vertical in the northwest and
southwest quadrants. Joint surfaces are planar and smooth
to rough and have an average spacing of 2 feet. Joint sur-
faces in the diorite porphyry in 11 The Fi ns 11 are pitted and
rough where feldspar and hornblende phenocrysts have
weathered out. Minor carbonate deposits were found on Set
I surfaces at joint stations WJ-4, WJ-6, and WJ-7 (Figure
6.12). The joints are continuous and generally tight.
Open joints are found at the surface in fracture zones and
shears. Set I parallels most major shears, fracture zones,
and alteration zones found at the site.
6-9
A subsidiary Joint Set (Ib) to Set I was found in the area
downstream of the dam centerline at joint station WJ-7.
This subset trends from 290° to 300° with an average dip of
75° northeast. This subset is also strongly developed at
joint stations WJ-1, WJ-2, and WJ-9 (WJ-2 is in the area of
the diversion tunnel outlet). The subset in the northwest
and southwest quadrants (downstream from WJ-4) is parallel
to the trend of the shears in geologic features GF 7A,
GF 78, and GF 7C (see Significant Geologic Features)
(Figure 6.3). This trend is also parallel to the Susitna
river between the dam centerline and diversion tunnel out-
1 et.
Joint Set II is northeast-trend·ing, ranging in strike from
045° to 080° with an average trend of 060° across the site.
Most dips are steep from 80° southeast to 80° northwest.
Set II is best de vel oped in the northeast and southeast
quadrants where the trend averages 050° with a preferred
dip to the northwest. At stations WJ-3 and WJ-5, near the
diversion tunnel entrance, Set II is more strongly develop-
ed than Set I, while at joint station WJ-6 in the diorite
porphyry approximately 200 feet upstream from WJ-3, no Set
II Joints were found. It is likely that the face of the
outcrop at this station was parallel to Set II joints
resulting in no exposure of that set. In the northwest and
southwest quadrants, Set II trends more to the east with an
average strike of 065° and dips vertically. Set II joints
are generally planar with smooth to rough surfaces. Joint
spacings range from 1 inch to 5 feet, averaging 2 feet.
Set II is generally continuous and tight. Open joints were
found on the south bank at WJ-1 and at several other out-
crops.
No shears or alteration zones were found associated with
Joint Set II.
Joint Set III is generally north-south trending, ranging in
strike between 340° and 030° with variable dips from 40°
east to vertical to 65° west. Set III is a minor set al-
though 1 oca lly pronounced in the northwest and southwest
quadrants. In the northeast quadrant, the average strike
and dip are 005° and 60° east. In the southeast, the
strike and dip are generally 350° and 65° west (WJ-7).
Fracture and shear zones parallel to Set III were mapped in
structural areas GF 6A, GF 6B, and in the "Fi ngerbuster"
(Figure 6.3). At GF 68, Set III forms numerous open joints
on the cliff face. Where present, the Set III joints range
in spacing from 1 ess than 1 inch in fracture zones to 5
feet, with an average of 1.5 feet. These joints are gener-
ally planar to irregular and rough. Minor carbonate was
6-10
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I
found at some outcrops in the southwest quadrant. Moder-
ately to steeply east-dipping Set III joints are 1 ikely to
be encountered in tunnels near the proposed dam centerline
and at the diversion tunnel outlet.
Joint Set IV consists of numerous low angle (dipping less
than 40°) joints of various orientations, the strongest
trend being 090° (Table 6.2). In all but the northeast
quadrant, these joints dip towards the Susitna River at
less than 30°. In the northeast quadrant, dips are both
towards and away from the river. Set IV joints are planar
to ·irregular, smooth to rough and discontinuous. Spacing
is generally 1 to 2 feet when present. No mineralization,
shearing, fracture, or alteration zones are associated with
this set. Set IV joints probably resulted from stress
relief after glacial unloading and/or erosion of the river
valley, and therefore should not occur at depth.
At WJ-2 and WJ-4, a strong local joint set striking approx-
imately 335° with a 30° to 70° dip to the southwest was
mapped. Minor shears parallel to this set were found near
WJ-4. This set may be encountered in tunnels downstream
from the centerline.
In summary, shears, fracture zones, and alteration zones at
the Watana site tend to para ll e 1 Joint Sets I and II I. No
major structures were found associated with Sets II and IV.
The Susitna River appears to be joint-controlled at the
Watana site. In the upstream area, the river parallels Set
II. In the dam centerline area, it is controlled by both
Set I and Set II, while downstream from the centerline the
river is controlled by shear and fracture zones related to
Joint Set I.
Shears, Fracture Zones, and Alteration Zones
This section defines and discusses shears, fracture, and
alteration zones and combinations of these features which
are shear/fracture zones and shear/alteration zones mapped
at the Watana site. Symbols denoting these features on the
geologic sections (Figures 6.4 through 6.8) are: shears
(S), fracture zones (F), alteration zones (A), shear/alter-
ation zones (S, A), and shear/fracture zones (S,F). For
the most part, these features are less than 10 feet wide
and discontinuous. Where more than 10 feet wide, both
boundaries have been delineated on the geologic map (Figure
6.3) and geologic sections. The individual characteristics
of shears, fracture zones, and alteration zones are des-
cribed below, while Subsection (iv) discusses the specific
areas in which these structures occur.
6-11
-Shears
Shears are defined as a surface or zone of rock fracture
along which there has been measurable displacement and is
characterized by breccia, gouge, and/or slickensides in-
dicating relative movement.
Two types of shears are found at the Watana site. The
first type, which is found only in the diorite, is called
healed shears and healed breccia. This type of shear
consists of a diorite breccia healed within a matrix of
aphanitic to fine grained andesite/diorite. The diorite
fragments range from less than 5 percent to 90 percent of
the zone and are generally subrounded. The matrix and
rock fragments, which are observed in both outcrop and
core borings, are fresh and very hard to hard. Figure
6.11 shows a 1-to-2-foot-wide healed sheared zone. The
contacts, although irregular, are tight and unfractured.
In outcrops, healed shears and breccia range from less
than 1 inch to about 1.5 feet. One foot offsets of these
features have been observed where they cross felsic
dikes. Two general orientations were found for this type
of shear: 305° dipping 45° to 70° northeast, and 300°
dipping 65° southwest.
Healed shears and breccias were found in virtually al1
boreholes. In all cases, the zone was found to be compe-
tent with high RQDs and high core recoveries. The
largest healed shear was up to 140 feet thick in COE
DH-11. No correlation could be made between the healed
shears and breccias noted in the cores and the surface
exposures. Therefore, these features were not delineated
~n the site geologic map. These features are interpreted
to be emp 1 a cement type shears which formed during the
last phases of plutonic activity when the magma was in a
semi-solid state.
The second type of shear found at the site is common to
all rock types and consists of unhealed breccia and/or
gouge (Figure 6.18). The breccia consists of coarse to
fine sand-size rock fragments in a silt or clay matrix.
Gouge is generally silt or clay material. Both the
breccia and gouge are soft and friable. Thicknesses of
these shears vary from less than 0.1 inch up to 20 feet,
but are generally less than 1 foot. Carbonate and chlor-
ite mineralization are commonly associated with these
shears. Some shears are partially to completely filled
with carbonate. Slickensides are found in most shears
and occur on both the carbonate and chlorite surfaces.
These shears are most often associated with fracture and
alteration zones. When found in association with these
6-12
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zones, they have been referred to as shear/fracture and
shear/alteration zones. Figure 6.18 is a photograph of a
typical shear which is within a fracture zone. These
zones will be discussed in more detai 1 in the Fracture
Zone and Alteration Zone subsections.
-Fracture Zones
Fracture zones are areas of very closely to closely
spaced (less than 1 foot) jointed rock where no apparent
relative movement has occurred. Fracture zones are com-
mon to all rock types and are found in both outcrop and
boreholes. Fracture zones in outcrop were found to range
from 6 inches up to 30 feet in width but are generally
less than 10 feet. In the boreholes, fracture zones were
found to range from less than 1 foot up to more than 100
feet wide as measured in BH-2. However, for the most
part in boreholes and outcrop, the fracture zones are
less than 5 feet wide.
Where exposed, they are easily eroded and form topograph-
ic lows or gullies, which have become filled with talus.
The fracture surfaces are generally iron oxide stained.
A coating of white carbonate is also commonly found on
the fracture surfaces.
-Alteration Zones
Alteration zones are areas where hydrothermal solutions
have caused the chemical breakdown of the feldspars and
mafic minerals. The products of alteration are kaolini-
tic clay from feldspar and chlorite from mafic minerals.
These zones are found in both the diorite and andesite
porphyry but appear to be 1 ess common in the andesite
porphyry.
Most of the information regarding alteration zones is
from the boreholes. Alteration zones are rarely seen in
outcrop because, l·ike the fracture zones, they are rela-
tively easily eroded and tend to form gullies which sub-
sequently become fi 11 ed with tal us. Alteration zones are
exposed on the surface on the north bank in "The Fins"
and in one outcrop at river 1 eve 1 near the dam center-
line. The degree of alteration is highly variable rang-
ing from slight, where the feldspars show discoloration,
to complete where the feldspars and mafics are completely
altered to clay and chlorite. In slightly altered dio-
rite, the rock is bleached to a yellowish green or gray
and is generally hard to moderately hard as seen in BH-3
from 933.2 to 948.9 feet (Appendix B). The slightly
altered zones have approximately 10 to 25 percent of the
6-13
feldspars stained or altered to clay. In completely al-
tered diorite, the rock is bleached to whitish gray or
very 1 i ght ye 11 owi sh gray. The rock fabric is preserved;
however, the materia 1 is soft and fr i ab 1 e. These com-
pletely altered zones are uncommon, and when encountered,
are generally 1 to 2 feet wide. Most alteration zones
found in the boreholes are slightly to moderately al-
tered. These zones are moderately hard with some thin
soft zones. Figure 6.15 is a photograph of an alteration
zone within "The Fins". As seen in the figure; the in-
tact diorite is in the upper right and is noticeably
darker than the lighter, bleached diorite that is altered
and sheared. Iron oxide staining is visible over a 2-to-
8-inch-wide carbonate band.
Widths of these alteration zones most often range up to
20 feet but are generally under 5 feet. An exception is
in BH-12 on the south bank which drilled over 300 feet
into an alteration zone (Figure 6.5, see Subsection
[iv]). Several shear/alteration zones are exposed in "The
Fins" and range from 10 to 55 feet wide.
The carbonate, which
tion zones, occurs as
to 0.5 inches thick.
tion and iron oxide
zones.
is also associated with the altera-
veins or joint filling generally up
Occasionally, sulphide mineraliza-
staining are also found in these
No increase in joint frequency is evident in association
with these alteration zones. Numerous thin ( <2 inches)
shears are associated with the alteration zones (Appendix
B). RQDs are generally low, because only fresh to
slightly altered rock is considered in taking RQD mea-
surements. Core recovery is generally more than 90 per-
cent within the alteration zones. The transition from
fresh to altered rock is gradational, generally occurring
over less than 1 foot.
(iv) Significant Geologic Features
The Watana site has several significant geologic features
which consist of broad areas of shears, fracture zones,
alteration zones, and/or combinations of these features.
Two of these areas, initially mapped by the COE (45) are
called "The Fins" and "Fingerbuster" (Figure 6.3). Other
areas or individual structures considered to warrant
detailed discussion have been identified on Figure 6.3 by
letters GF 1 through GF 8 and are discussed individually
below.
6-14
r-,
r
1"""'·
I
,...
J
r""
I
;(
!!""' ~
.....
-"The Fins"
"The Fins" consists of major zones of shearing and alter-
ation. This feature is located on the north bank of the
Susitna River upstream from the proposed diversion tunnel
intake portal (Figure 1.2). "The Fins" consists of a 400-
foot-wide zone containing a series of northwest trending
shear/alteration zones. Gullies formed by erosion of
these structures are separated by intact rock bands or
ribs ranging from 5 to 50 feet wide.
Three major and numerous minor shear/alteration zones
have been mapped in "The Fins." From upstream to down-
stream, the major zones consist of a 20-foot-wide zone in
the area of the diorite and diorite porphyry contact; a
55-foot-wide zone; and a 30-foot-wi de zone. These zones
are separated by intact competent rock bands or ribs.
Large gullies with thick talus have formed in these
zones, resulting in poor rock exposure. These zones
trend in a northwest-southeast direction and are near
vertical. Figure 6.16 is an aerial photograph of "The
Fins" looking northwest along the strike. The 55-foot-
wide gully (as measured at river level) splits ·into two
branches 20 to 30 feet wide at approximate E 1 evat ion
1650. A 10-foot-wide zone of altered and crushed rock is
exposed near river level on the east side (Figure 6.15),
and there is a 3-foot-wide zone of sheared/fractured and
moderately to severely altered rocks on the west side of
the main gully. The remainder of the gully is covered by
talus. Based on these exposures, it has been assumed
that the shear and a 1 terat ion zones extend across the
full 55-foot width of the gully.
There are carbonate veins para 11 el to these zones and
others which transverse them. Carbonate thicknesses
range from 0.5 to 8 inches. The veins are fractured but
no offsets were noted.
Minor east-west and north-south trending shears also
occur in "The Fins." These features are generally less
than 1 foot wide. Two north-south trending shears mapped
in "The Fins" are 1 foot and 3 feet wide, respectively,
and dip 57° to the west. Slickensides on carbonate coat-
ings indicate an oblique sense of movement. Figure 6.14
shows a 3-foot-wide north-south shear. This shear
appears to project across the river in the vicinity of
the upstream cofferdam and align with a topographic trend
on the south bank. Lineations associated with the north-
south shears are indicated on Figure 6.16.
6-15 •
The overall trend of "The Fins" is 300 to 310°. Dips are
steep to vertical. The extension of this feature to the
northwest is inferred from seismic refraction lines SL
81-15, SL 81-15x, and SW-3 which show low seismic velo-
cities (10,000-12,700 feet per second) in bedrock, as
well as low bedrock elevation along the projection of
"The Fins" (Figure 6.5). In contrast, the bedrock seis-
mic velocity northeast and southwest of this feature is
about 18,000 feet per second (Appendices Hand I).
Beyond the seismic lines, "The Fins" has been ·inferred to
trend along a topographic low (Figure 6.16). Altered
rock found ·in COE boreholes DR-18, DR-19, and DR-20 in
Borrow Site 0 may also have been drilled in this feature
(Figure 5.1). The topographic low projects to Tsusena
Creek, where along the northwest bank, an altered and
sheared outcrop of granodiorite is exposed. This outcrop
exposure is approximately 325 feet wide and is character-
ized by northwest, north-south, and east-west trending
shears.
The continuation of "The Fins" to the southeast beyond
the south bank of the Susitna River is uncertain. On the
south bank across from "The Fins," there is a topographic
low in Quarry L (Section 6.3[i]), which is the inferred
location of "The Fins" structure. Beyond this area, no
outcrops or topographic trends could be correlated to
this feature. The trace of this feature is also support-
ed by mapping activities performed by Woodward-Clyde Con-
sultants during their seismic studies carried out during
1980-81 (57,58) •
• Geologic Feature GF 1
GF 1 is the region downstream of "The Fins" in the vic-
inity of the proposed upstream cofferdam and diversion
tunnel portals. For discussion purposes, the area has
been divided into two subareas: GF 1A on the north
bank and GF lB on the south bank (Figure 6.3).
Subarea GF 1A contains east-west and northwest-south-
east trending shears and fracture zones. The east-west
shears are oriented between 280° and 290° with vertical
dips. Shear widths are generally 1 foot or less. The
northwest-southeast (310 to 320°) trending shears are
up to 3 feet wide and are parallel to two fracture
zones. These zones are 25 to 30 feet wide and form
gullies. These features are likely to be encountered in
the proposed diversion tunnels (Figure 6.7), intersect-
ing the tunnels at high angles (Figure 6.3). The most
significant structure in GF 1B is a 20-foot-wide frac-
6-16
-
-I
-I
,......
I
ture zone trending at 315° and dipping vertically. A
1-foot-wide zone of possible gouge was found in the
zone. Approximately 100 feet to the northeast, a 4-
inch-wide shear was mapped parallel to this fracture
zone. The correlation of the structures in GF 1A with
those in GF 1B are uncertain •
• Geologic Feature GF 2
GF 2 (Figure 6.3) is approximately 80 feet wide and
consists of northwest-southeast trending fracture zones
with minor shears. On the south bank, GF 2 is coinci-
dent with a deep, talus-filled gully. Outcrops on
either side of the gully are very closely jointed (Set
I). Dips are vertical or steep to the north.
On the north bank, there is no strong topographic ex-
pression of the GF 2 structure. A 30-foot-wi de gully
postulated as a fracture zone was mapped at about Ele-
vation 1700. Joint orientations in this area are simi-
lar to those on the south bank. The GF 2 structure was
projected farther to the northwest in alignment with a
low seismic velocity {14,800 feet per second) zone on
SL 80-3 (Appendix I). Based on this evidence, it is
likely that this fracture zone will be encountered in
the diversion tunnel (Figure 6.7), intersecting the
tunnel at an oblique angle •
• Geologic Feature GF 3
GF 3 is located on the south bank (Figure 6.3). This
area contains fracture zones and minor shears. These
structures strike predominantly at 320° and have verti-
ca 1 to steep northeast dips. A 20-foot-wi de fracture
zone was mapped in a deep gully paralleling Joint Set
I. Parallel to this zone is a 4-to-6-foot wide zone of
breccia with heavy carbonate coating. Also in GF 3 is
a 3-to-6 foot-wide shear /fracture zone which trends
north-south and dips 60° east. No features similar to
those in GF 3 were found on the north bank •
• Geologic Feature GF 4
GF 4 consists of two shear/fracture zones (GF 4A and
GF 4B), each about 10 feet wide (Figure 6.3). The
overall trend of these zones is 315° with a dip of 70°
to the east. On the south bank, GF 4A and GF 4B were
mapped in a very deep, talus-filled gully. Outcrops
in the gullies have very closely to closely spaced
joints along Joint Sets I, II and III. All joints are
heavily carbonate coated. Where mapped, GF 4A was
6-17
found moderately weathered with pass i bl e alteration.
Seismic velocities in this area (SL 80-3) are lower
(15,000 feet per second) than the usual 18,000 to
20,000 feet per second velocities measured in less
fractured diorite. GF 4A and GF 46 have been projected
across the river to correlate with two fracture zones
mapped between Elevations 1650 and 1750. These frac-
ture zones are also in a deep gully (Figure 6.17).
GF 4A has been tentatively correlated with the shears,
fracture zones, and alteration zones found in borehole
BH-3 (Figure 6.4) between borehole depths 414.4 and
622.4 feet. These zones are slightly to moderately
altered and generally moderately hard, though 1 oca lly
soft and friable in the shears. RQDs between 474 and
530 feet are 0 percent because of the moderate altera-
tion. Throughout the rest of the zone, RQDs are 90 tg
100 percent with permeabilities generally 10-
cm/sec. Many of the joints are healed by carbonate.
The correlation of the zones in BH-3 with GF 4A has
been based on the assumption that the zones are trend-
ing northwestward. This assumption is supported by the
fact that this fracture zone would have been intersect-
ed in either BH-4 or DH-11 if it had had an east-west
or a north-south strike.
GF 4B has been correlated with a shear/fracture zone
and alteration zone in DH-11 (Figure 6.4) at borehole
depth 189.0-197.7 feet. The fracture zone is iron
oxide stained. The upper three feet of the zone is
hydrothermally altered and contains 0.2 foot of clay
gouge and breccia. Permeabilities in this zone are
high, typically ranging between 10-2 em/sec to
10-3 em/sec. Most joints are coated with sandy
silt/clay and minor carbonate. The projection of the
GF 4A and GF 4B structures would intersect the proposed
diversion tunnels (Figure 6.3) at a high angle •
• Geologic Feature GF 5
GF 5 is located near the proposed dam centerline and
consists of fracture zones and minor shears (Figure
6.3). The area is approximately 60 to 70 feet wide and
trends northwest-southeast (310 to 320°). The dip is
steep to the northeast. GF 5 on the north bank of the
river falls within a deep gully bounded on the down-
stream side by a 75-foot-high diorite cliff (Figure
6.17). Two northwest trending shears in the gully are
as much as 10 feet wide and dip at 75° and 80° to the
northeast and southwest, respectively. Although there
is no topographic expression of these features on the
north abutment, it has been correlated with several
6-18
~I
--
shear and fracture zones intersected in borehole DH-9
(Figure 6.4) and with a 130-foot-wide, low-velocity
zone on SW-2 (12,500 fps) (Appendix I). The joints and
fractures in DH-9 are generally iron oxide-stained and
carbonate-coated. Faint slickensides are observed on
some surfaces. The RQDs in DH-9 are low, with an aver-
age of 57 percent. Permeabi 1 it i es are generally be-
tween 10-1 em/sec and 10-3 em/sec and decrease
with depth. No 1 ow-velocity zones were encountered
along SL S0-2 (Figure 6.3) that could imply continua-
tion of this feature to the northwest (Appendices H and
I).
On the south bank, the GF 5 structure is correlated to
a 10-foot-wide fracture zone at river level and a ser-
ies of minor northwest-trending shears between Eleva-
tion 1650 and 1S50. Farther up slope, it is correlated
with a moderately low (15,000 feet per second) velocity
zone a 1 ong SL S0-3 and a bedrock depression found in
borehole DH-25 (Figure 6.S). In this area, overburden
thickens from 10 or 15 feet to nearly SO feet. On the
north bank, GF 5 wi 11 1 ikely intersect the proposed
diversion tunnels (Figure 6.3) •
• Geologic Feature GF 6
GF 6 is divided into two subareas: GF 6A on the north
bank and GF 68 on the south bank (Figure 6.3). Both
subareas are characterized by north-south trending
structures. GF 6A is approximately 25 feet wide and
occurs in a north-south trending gully whose walls are
very closely jointed, severely weathered, possibly al-
tered, and locally friable. A strong north-south
trending joint.set (Set III) with vertical and steep
dips occurs in this area.
Subarea GF 6B is characterized by north-south shears,
fracture zones, and open joints; east-west trending
open joints; and northwest trending shears (Figure
6.3). These features are exposed in deep gullies in
the high rock cliff face on the south side of the river
(Figure 6.1S). The north-south shears have up to 2.5
feet of gouge. Open joints along this trend generally
dip at about sao to the east and are up to several feet
wide. East-west trending joints dip 70° to sao north
towards the river. The intersection of these joint
sets has resulted in block slumping. Details of
northwest trending shears in GF 6 are discussed in GF 7
below. No direct evidence could be found during this
study to correlate GF 6A and GF 6B.
6-19
• Geologic Feature GF 7
GF 7 is divided into three subareas: GF 7A on the
north bank; GF 7B, which trends across the river from
the north bank to the south bank; and GF 7C, which lies
between these two areas on the north bank (Figure 6.3).
GF 7 is characterized by numerous northwest (290° to
300°) trending, nearly vertical shears. These shears
are genera11y 1 foot or less wide and are often associ-
ated with fracture zones up to 10 feet wide.
Subarea GF 7A is about 40 feet wide and lies in a shal-
l ow northwest trending gu1ly. An outcrop on the east
side of the GF 7A structure at approximate Elevation
1850 is a moderately soft, altered diorite. The extent
and orientation of GF 7A are uncertain; however, based
on field mapping, it appears to trend in a northwester-
ly direction.
On the north bank in the andesite porphyry. subarea
GF 7B lies in a deep, vegetated gul1y trending at 290°
(Figures 6.3 and 6.19). Exposures in the gully show
very closely spaced vertical fractures trending approx-
imately 290° with thin zones of breccia and gouge. The
andesite porphyry on the gully walls is slightly to
moderately weathered. Figure 6. 20 shows where GF 7B
intersects the "Fingerbuster" at river level on the
north bank (see next subsection). Subarea GF 7B has
been projected across the river to correlate with fea-
tures exposed a 1 ong the base of the c 1 iffs in area
GF 6B (Figure 6.3). GF 7B appears to dip at 75° to the
north. This is based on the slope of the cliff face
and dips of shears behind and at the base of the cliff.
GF 7B was also correlated with a shear zone intersected
from 97.8 to 104.0 feet in OH-1 (Figure 6.6). This
zone is s1ightly to moderately altered, with shears
less than 6 inches wide. The rock is moderately hard,
but soft in shear zones. RQDs are generally 1 ess than
40 percent in OH-1 with permeabilities about 10-3
em/sec. Shearing may also exist in DH-3 where core
loss of 6.7 feet occurred near the top of rock between
94.0 and 104.7 feet. Subarea GF 7B projects to the
southeast from the river bank and is exposed in a
steep-walled, 10-to-15-foot wide gully at the andesite
porphyry/diorite contact at Elevation 1750. GF 7B
crosscuts both of these rock types. The rock in the
zone itself has a granular nearly schistose character
typical of cataclastic rocks. The rock has been healed
and resheared. No exposures of GF 7B were found beyond
this point; however. it has been tentatively correlated
to a 10,000-feet-per-second zone on seismic line SW-1
6-20
!"""··,
-I
-
--1
~ ' (
I
-
and to shear/fracture zones in DH-23 (Figure 6.5).
This correlation is questionable, since the zone was
not intersected by BH-8, which lies between these fea-
tures.
Subarea GF 7C is bounded by the 11 Fi ngerbuster, 11 subarea
GF 7A and a north-south trending gully on the east side
(Figure 6.3). This area has a step-like appearance in
section because of a series of east-west trending
ridges and gullies between 10 and 20 feet wide. The
11 Steps" trend along the 290° to 300° shears which are
parallel to Set I joints in this area. Numerous minor
shears in this area have resulted in gullying and ero-
sion. This area was interpreted to be a series of
near-surface slumps along the northwest-trending
shears. It is assumed that GF 7C extends to near El e-
vation 2200, where a low-velocity zone was found on
SW-2. The size and stability of these blocks will
require investigation in subsequent phases of work.
-
11 Fi ngerbuster"
The second most prominent structural feature at Watana is
the major zone of shears called the 11 Fingerbuster,11 lo-
cated about 2, 000 feet downstream of the proposed dam
centerline. On the north bank, this structure is par-
tially exposed in a 40-foot-wide gully filled with a deep
talus deposit. The andesite porphyry/diorite contact is
coincident with this structure to about Elevation 2000.
An outcrop in the gully 100 feet above river 1 eve 1 is a
highly fractured diorite breccia in an andesite matrix.
The rock is moderately to severely weathered. Joints are
very closely to closely spaced in the gully, trend 330°
(Set I) and oo (Set III), and dip steeply to vertical.
Slickensides on the gully walls indicate a vertical dis-
placement. Another outcrop at Elevation 1850 on the east
side of the gully is very fine to medium grained diorite
which has been intruded by thin veins of andesite con-
taining diorite fragments.
BH-2 was dri 11 ed across the "Fi ngerbuster 11 structure to
determine its location at depth. Between borehole depths
of 71.2 and 177.1 feet, the borehole intersected a shear/
fracture zone which was also coincident with the andesite
porphyry/diorite contact at approximately 126 feet (Fig-
ure 6.7). The rock in this zone contains major shears and
zones of alteration. RQDs and core recoveries were gen-
erally less than 50 percent and often 0 percent. A gully
that branches from the main 11 Fingerbuster 11 to the north-
west is inferred to be another shear and fracture zone.
6-21
The extension of the "Fingerbuster" to the south is based
on a strong north-south topographic 1 i neament which ex-
tends to Elevation 1800 on the south bank. No outcrops
were found in this gully. This feature, which is down-
stream from the main dam structure, has been considered
significant in design. Every effort has been made to
avoid placing major civil structures in this area •
• Geologic Feature GF 8
GF 8 is a wide (approximately 400 feet) northwest-
trending structure on the south bank of the river which
consists primarily of alteration zones but also in-
cludes shear and fracture zones (Figure 6.3). This
area was delineated during the 1981 field season for a
possible underground powerhouse on the south bank.
As a result of the scarcity of bedrock exposure in this
area, all geologic interpretation has been based on
seismic refraction surveys and drilling. In 1981, an
1,800-foot seismic line (SL 81-21) was shot along a
northeast-southwest trend across the south bank (Figure
6.3). A zone about 1,100 feet long of low seismic vel-
ocity in bedrock was found. Velocities were about
12,000 feet per second in this zone and 18,000 feet per
second in the adjacent zones on each side. Poor qual-
ity rock was confirmed by BH-12 which was dri 11 ed to
the southeast to intersect this structure (Figure 6.5).
At about Elevation 1700, the boring encountered a near-
ly continuous zone of altered diorite with minor
shears. Alteration is generally slight but includes
zones of moderate to severe a 1 terat ion. Shears are
less than 6 inches wide. Joints are generally closely
spaced and healed with carbonate. Chlorite is found on
some joint surfaces.
The trend and dip of this structure was based on corre-
lation between SL 81-21, SW-1, BH-12, and DH-28. DH-28
was drilled vertically to a depth of 125.2 feet in an-
desite porphyry. The rock in the boring is slightly to
moderately altered and moderately hard. Joints are
very closely to closely spaced and iron oxide stained
throughout. RQDs are generally less than 50 percent
and often 0 percent. It is postulated that DH-28 was
drilled ·in a shear/fracture zone related to the GF 8
structure (Figure 6.8). East of DH-28, SW-1 shows
zones of alternating high (17,500-20,000 feet per
second) and low (12,000-13,000 feet per second) seismic
velocity bedrock. No evidence of shearing or altera-
tion was found in BH-8, OH-12, DH-23, or DH-24 or in
any outcrops on the south bank (Figure 6.5). This
6-22
(d)
-
observation served to limit the northeastward extent of
GF 8. In defining the trend of GF 8, it was assumed
that this structure would follow the major northwest-
southeast structural trend found at the site. The
southwest 1 i mit of GF 8 was based on the change from
1 ow to high bedrock velocity on SL 81-21. The south-
west contact was assumed parallel to the northeast
1 imit. The dip of the structure, based on the seismic
line and information from BH-12, is assumed to be about
70° to the southwest (Figure 6.5).
Rock Quality Designation
The Rock Quality Designation (RQD} (13} was determined for all
rock cores drilled by Acres and COE and is graphically shown on
the Summary Logs in Appendix B. Excluded from this series of bor-
ings are COE DR-16, DR-17, DR-18, DR-19, DR-20, and DR-22 which
were rotary drilled without core recovery and, therefore, no RQDs
were obtained. A tabulation of the RQD values is provided in
Tables 6.3 and 6.4. As noted in the tables, rock quality encoun-
tered in the drilling was generally good to excellent with RQDs
averaging between 75 and 90 percent. In general, rock quality
improves with depth, with the upper 50 to 80 feet of rock being
weathered and more fractured. Below this weathered zone, rock
quality is good to excellent with only localized zones of frac-
tured and sheared rock. These zones generally range in thickness
from 1 to 5 feet, but can be up to 30 feet. RQDs correlate well
with the permeability tests (Section 6.1[f]) which is generally a
function of rock quality.
Poor quality rock was found in BH-2 which drilled through part of
the "Fingerbuster" shear zone. This borehole was sited downstream
from the zone and drilled at an azimuth of 045° and a dip of 55°.
As seen in the boring logs, the shear zone was intersected at a
borehole depth of approximately 70 feet and continued to a hole
length of approximately 100 feet (vertical depth 65 to 80 feet).
This zone, which corresponds with the andesite porphyry/diorite
contact, consists of highly fractured, severely weathered brec-
ciated and sheared rock. Repeated grouting was required to main-
tain hole stabi 1 ity. Below this zone, rock quality improved with
only localized zones of low RQDs encountered around borehole depth
of 200, 210, and 250 feet. Other poor quality rock was encoun-
tered in several shallow COE holes (DH-1 and DH-28). These holes
were drilled to a depth of less than 125 feet and reflect the poor
quality, near surface weathered rock conditions.
In general, weathering appears to be primarily physical in nature,
with weathered rock being about 40 feet deep at the dams it e. The
weathering is light to moderate in joints, with penetration gener-
ally 1 ess than a inch into the unbroken rock. Shear and fracture
zones are considerably more weathered, and many of the shear zones
6-23
exhibit chemica 1 weathering and hydrotherma 1 alteration. Detai 1 s
of these zones are discussed in Section 6.1 (c).
The intact rock is classified as Class B "high strength" and has a
high static modulus to compressive strength ratio of 500. Rock
overall classification is BH (14).
(e) Rock Properties
Representative NQ (1.77 inches) rock core samples of andesite por-
phyry, diorite, quartz diorite and granodiorite samples were sel-
ected from BH-1, -2, -3, -4, -6, -8, and -12 for laboratory test-
ing. Results of the testing are presented in Tables 6.5 and 6.6
and are discussed below. Since the properties of diorite, quartz
diorite, and granodiorite were found to be similar, they have been
included under the heading of diorite. Photographs of typical
rock testing is shown in Figure 6.21.
(i) Unit Weight
Dry unit weights were determined in conjunction with com-
pression and tensile strength tests. Dioritic rocks aver-
aged 167 pcf and andesite rocks averaged 165 pcf.
(ii) Static Elastic Properties
Elastic properties were measured under unconfined compres-
sion using electronic strain gages bonded onto the sample
in horizontal and vertical directions. Stress, diametric
strain and volumetric strain were calculated and plotted
against axial stress from which the tangent modulus at 50
percent failure stress, secant modulus, and Poisson's Ratio
were determined. Results are presented in Figure 6.22. An
average of all test results shows:
Rock Type
Andesite
Diorite*
Combined, all samples
Static ~odulus
(x 10 psi)
10.2
9.5
9.64
Poisson's
Ratio
0.25
0.23
0.24
*Includes diorite, granodiorite and quartz diorite
(iii) Dynamic Elastic Properties
Compressional (V ) and shear (Vs) wave velocities were
measured on two ~oritic samples giving:
6-24
~--,
~'
i>1""'
I
Dynamic Modulus
(x 106 psi)
10.1
(iv) Direct Shear Tests
Poisson's Ratio
0.31
Vp
(fps)
19508
Vs
(fps)
10267
Three types of direct shear tests were performed:
{1) Natural discontinuity
(2) Polished rock on rock
(3) Polished rock on mortar
Test results are plotted on Figure 6. 23. A summary of the
results are:
Diorite
Natural joint, rough, planar
with carbonate, dry
Natural discontinuity with
inferred cohesion
Polished rock on rock, dry
Polished rock on mortar, dry
Polished rock on mortar,
dry with inferred cohesion
~ Peak
38°
21.5°
44°
~ Residual c(psi)
28° 0
30° 29
18° 0
31° 0
31° 24
Polished rock on rock tests give a material's lowest fric-
tion angle. This angle does not include effects of natural
surface undulations or roughness. Therefore, a 11 Waviness
angle,. is applied to obtain a more representative value for
design. This ,.waviness angle,. is based to a ·large degree
on observed field·conditions of natural joint surface and
site geology.
The results of the natural joint test quoted above show
relatively high peak and residual values. Analysis of ver-
tical vs. horizontal displacements shows a 10° incline,
which appears to reflect this 11 Waviness angle,. for ·in situ
conditions. As noted on Figure 6.23, two possible inter-
pretations of the shear strength are given: a higher peak
without cohesion or a lower peak including an apparent co-
hesion. The results are typical of natural joints and rock
on concrete (21).
Diorite on mortar tests show that the shear strength is
initially high but decreases to residual values with higher
normal loads and greater displacements.
6-25
(v)
(vi)
Com~ressive Strength Testing
Compressive strengths were measured in unconfined compres-
sian and by point loading.
-Unconfined Com~ression
Results of unconfined compressive strength tests show:
Number High Low Mean + Standard
Rock Ty~e Of Tests ~) ( ~s i ) Deviation (~si)
Andesite 8 26,206 6,100 18361 + 5978
Diorite 32 29,530 4,473 17593 + 6080
Both rock types are isotropic and show relatively high
strengths. Frequency plots (Figure 6.24) show 90 percent
of all cores tested above 10,000 psi and approximately 70
percent of results plotted between 11,755 and 23,736
psi.
-Point Load Testing
Boreho 1 es BH-6 and BH-8 were profi 1 ed at 15-to-20-foot
intervals using a Terremetrics T-500 point load tester.
Frequency plots (Figure 6.25) show 95 percent of all test
results are more than 10,000 psi and, assuming a normal
distribution, nearly 70 percent of all tests fall within
the 18,114-to-38,390-psi range. No distinction between
the various rock types could be noted.
These apparent strengths are substantially higher than
those defined by unconfined compressive strength tests.
The probable cause is that rock strength is proportional
to the physical dimension of the test sample. For uncon-
fined compression tests, lower strengths for larger size
cores of the same rock are common (23). Si nee a point
1 oad tester tests the mini mum vo 1 ume of rock, higher
results would be expected.
Both types of tests, however, show the intact rock to be
of high strength with an average to high modulus ratio
( BM, B H ) ( 14) •
Tensile Strength
Number of High Low Mean + Standard
Rock Tl~e Tests ( ~s i } {~si} Deviation ( ~s i )
Andesite 3 1718 1616 1683 + 58
Diorite 8 2450 602 1906 + 576
6-26
,:G~''
~]
-t
(f)
(vii)
Test results show that intact rock tensile strength (Braz-
ilian Split) is relatively high, which implies a high in-
tact rock shear strength. The lowest strength was obtained
on altered diorite sample while sound, competent cores
tested at least three times higher.
Summary
The rock test results presented in this section are con-
sidered adequate for preliminary design purposes. Exten-
sive geotechnical work including drilling, down-hole test-
ing, geophysics, exploratory adits, laboratory and in situ
testing, will be required before the final design para-
meters can be determined for each structure. However,
tests performed during this, as well as previous studies,
show the rock to be of excellent quality for constructing
both surface and subsurface hydropower facilities at
Watana.
Rock Permeability
Water pressure tests performed both by the COE and Acres (Section
5) confirm that rock permeability at Watana site is controlled by
the degree of jointing, fracturing, weathering and permafrost
within the bedrock.
Results of permeability tests are graphically shown on the Summary
Logs and tabulated in Appendices B and 0, respectively. Water
pressure testing caul d not be performed in sever a 1 zones because
of hole caving. In BH-2, testing was terminated at a hole depth
of 70 feet, and in BH-12, the bottom 200 feet caul d not be
tested.
The rock permeability does not vary significantly within the site
area, generally ranging between 1 x 1o-4 em/sec to 1 x
10-6 em/sec. As waul d be expected in fractured rock, high
perrneabil ities are found near the surface with low permeabil ities
at depth (Figure 6.26). Similarly, high permeabilities are also
encountered in the more highly fractured rock zones.
An example of this was found in BH-1 (Appendix B) where higher
permeabilities, about 1o-4 em/sec, were measured in a zone
from 150 to 160 feet, which corresponds to a highly fractured zone
with 0-RQDs and low cor4 recovery. Similarly, high permeabili-
ties, about 1.6 x 10-em/sec, were measured in BH-6 at a
depth of 464 feet, which corresponds to a soft mineralized zone
with 0-RQDs.
6-27
In BH-3 and BH-4, at the estimated powerhouse cavern depth of
approximately 1450 to 1400 Elevation, permeabilities are low, in
the range of 2 x 10-6 em/sec. The permeabi 1 ity of rock above
the powerhouse complex is generally low, ranging between 1 x
1o-5 to 1 x 10-6 em/sec.
Artesian conditions were encountered in BH-12 at a depth of 325
feet, which corresponded with the granodiorite/andesite altered
and sheared contact. Because of the structural relationship of
these two rock units (see Section 6.1 [b]), higher permeabilities
may be expected where this contact is intersected.
Permafrost conditions within the rock have an effect on permeabil-
ity. Ice-filled joints and fractures prevent water from flowing
through the rock mass, thereby giving erroneously low permeability
values (Section 6.1 [h]). Thawing methods have, therefore, been
developed in those permafrost areas for foundation treatment under
the dam and associated structures.
(g) Groundwater
(i) General
As stated in 6.1(b), the Watana damsite lies within a large
dome-shaped diorite pluton. Groundwater data for the site
is based on borings, installed piezometers, and field ob-
servations.
This section wi 11 address only the groundwater conditions
at the damsite and construction areas. Discussions of the
groundwater in the borrow sites and relict channel will be
individually addressed in Sections 6.2 and 6.3, respec-
tively, while the groundwater conditions in the reservoir
are briefly discussed in Appendix K.
( i i ) Dams ites
For the most part, the groundwater at the main damsi te is
confined to open fractures and joints within the bedrock.
Therefore, the movement of groundwater is determined by the
rock permeability and continuity of these open fractures
and joints. Gradients within the damsite proper are down-
slope towards the Susitna River, with the groundwater gen-
erally representing a subdued replica of the topography.
The groundwater regime is complicated at the Watana site by
the existence of nearly continuous permafrost on the south
bank and possibly intermittent permafrost on the north bank
(Section 6.1 [h]).
6-28
~'
-
-
( i i i )
As a result of the permafrost, the groundwater tab 1 e is
relatively shallow on the left abutment. Boreholes BH-8,
BH-12, DH-12, DH-25, and DH-28 all encountered water levels
within 10 feet of the surface. Numerous seeps, springs,
and wet areas are evident throughout the left bank. This
shallow water table is the "thawed" layer perched on top of
the permafrost zone. On steeper slopes (Elevation 1900 to
river level), groundwater flows through the weathered rock
zone and on top of the rock surface beneath the ta 1 us
slopes.
Groundwater was encountered in two deep boreho 1 es beneath
the permafrost on the south bank. In BH-8, the water level
was recorded at approximately 170 feet, whereas BH-12
intersected artesian conditions at hole depth 350 feet or
approximately 200 feet beneath ground surface. (This depth
corresponds with the mapped sheared and altered zone [GF 8]
on the left abutment [Figure 6.3]). This hole, which was
drilled in 1981, has continuously flowed at several gallons
per minute since it was drilled. During its drilling,
water was noted flowing from an adjacent borehole (immedi-
ately uphill from BH-12) indicating communication along
this zone.
Further investigations and instrumentation will be required
in subsequent phases of study to accurately define the
groundwater conditions in this area.
Groundwater on the north abutment has been monitored by
piezometers installed in BH-3 and BH-6. Based on this
data, the groundwater table appears to be deep on the north
bank. Water levels monitored ·in BH-6 and BH-3 show the
water table to range between 107 to 150 and 280 feet below
ground surface, respectively. The fluctuations noted in
BH-6 appear to be directly correlative with changing season
precipitation.
Subsurface Structures
Structures such as penstocks, powerhouses, and transformer
galleries that will be constructed below the groundwater
tab 1 e wi 11 1 ike ly experience water inflows through open
joints, fractures, and shears. However, rock permeabili-
ties in these areas are expected to be low (Section 6.1
[f]).
(iv) Surface Facilities
As stated in (ii), any surface structure on the south bank
can expect to encounter a perched water table on top of the
permafrost. Shallow structures on the upper portions of
6-29
the north bank are 1 ike ly to be above the water tab 1 e,
while structures near river level will likely intersect the
phreatic surface.
The construction of the Emergency Spillway will likely en-
counter groundwater within the shallow overburden and
weathered rock where perched water table and aquicludes can
be expected.
Camp facilities are sited within the relict channel and can
expect a surface water condition during the summer thaw.
The groundwater table in this area is addressed in Section
6. 2.
(h) Permafrost
( i) Genera 1
The Watana area has been mapped as a zone of discontinuous
permafrost (19).
Permafrost features consisting
solifluction slides, beaded
graphy, skin flows, co 11 apsed
found throughout the region.
of frozen tills, bimodul and
streams, thermokarst tapa-
pi ngos, and thaw 1 akes are
Based on regional temperature readings from the Summit and
Cantwell, Talkeetna and Curry areas, it appears that the
site is very near to the freezing isotherm, which is sup-
ported by one year's temperature data for Watana that show
an average temperature of approximately 0. sac (3 7). These
temperatures suggest that the site is in an area where
there is no ongoing development of permafrost.
Thermistor readings at the damsite and borrow sites are
shown in Figures 6.27 through 6.29. An analysis of this
data is contained in the following subsections and Sections
6.2 and 6.3.
(ii) Damsite
As previously stated, permafrost appears widespread
throughout the 1 eft abutment. A 11 of the seven bore hales
drilled on the left abutment, except BH-12, froze back
within 30 feet of the surface. Permafrost was measured
throughout the full hole depths in DH-12, DH-23, DH-24,
DH-28, and to a minimum depth of 175 feet in BH-8 where the
instrument was blocked.
6-30
-
r
-
r
r
-
r
, r
r
( i i i )
A total depth of permafrost in the left abutment is esti-
mated to be 200 to 300 feet. Temperature readings, how-
ever, show this to be "warm" permafrost with readings gen-
erally ranging between 0 and -laC (Figure 6.27).
The extent of permafrost in the underlying river alluvium
and bedrock is based on information obtained from DH-21 and
BH-6. DH-21 drilled by the COE shows apparent permafrost
to the top of rock. No deeper readings caul d be obtai ned
because of hole collapse. BH-6, drilled on the·right abut-
ment and inclined beneath the river, shows temperatures
below freezing from hole depths ranging from approximately
95 feet to between 200 to 250 feet, or about 100 to 150
feet beneath rock surface (Figure 6.27).
Drilling of the vertical holes by the COE in the river
alluvium showed no apparent permafrost in either the allu-
vium or bedrock. Further investigations will be required,
however, in this area to confirm the permafrost condi-
tions.
No permafrost was encountered in any of the seven bar i ngs
drilled on the right abutment, with the exception of the
previously discussed BH-6. The only other instrumented
hole on this abutment is BH-3, which shows a very consis-
tent data plot with a minimum temperature of 1.2ac at about
120 feet. Thermal gradients measured in several of the
borings show average gradients of about laC per 200 to 300
feet with the exception of BH-3 which shows a gradient of
lac per 550 feet. This lower gradient may be caused by
groundwater flows within the rock mass resulting .in a
decreased temperature.
Surface Structures
Excavation for surface structures may encounter sporadic
"warm" permafrost or annua 1 frost on the right abutment and
more or less continuous permafrost on the left abutment.
Annual frost penetration appears to be about 8 to 16 feet
in the rock and up to 40 to 50 feet in alluvium.
Although no permafrost was found in the areas of the pro-
posed Emergency Spillway, for construction purposes, it
should be assumed that 1 ocal i zed permafrost may be encoun-
tered that would require thawing and foundation treatment.
(iv) Camp and Access Roads
The camp fac-ility has been sited in the general area of the
relict channel (Section 6.2). Local areas of permafrost
can be expected in this area with zones of deeper seasonal
frost encountered beneath the tundra cover.
6-31
Permafrost can also be expected locally along the access
and construction haul roads in overburden cuts at depths of
0 to 20 feet. Permafrost in the bedrock is not expected to
pose any major engineering constraints. Care will be
required in designing cut slopes in permafrost terrain to
insure long-term slope stability. Further investigation in
these areas will be required to accurately define the perm-
afrost conditions.
6.2 Relict Channels
(a) Watana Relict Channel
(i) Introduction
In 1975, seismic refraction surveys performed by the COE
identified a large, deep overburden deposit on the right
bank extending between Deadman and Tsusena Creeks. This
large, soil-filled depression was interpreted by the COE as
a possible relict channel of the Susitna River. Further
seismic work was performed in the channel by the COE in
1978 and by Acres in 1980-81. To date, approximately
70,000 linear feet of seismic refraction surveys have been
performed in this area. In addition to the seismic work,
the COE drilled 8 deep rotary borings in the channel to
identify the stratigraphy and to verify the seismic refrac-
tion interpretation. Numerous shallower auger holes were
drilled in the area during 1980-81 primarily to assess bor-
row materials. Figures 5.1 and 6.43 show the extent of
exploration performed in and adjacent to the channel area.
All of this data has been used in defining the location,
configuration, and material properties of the relict chan-
ne 1. The accuracy of the data in defining the extent and
configuration of the channel is considered good. Verifica-
tion of seismic interpretation for top-of-bedrock by the
COE's boring showed accuracy within 10 percent for the 1975
data and 5 percent for the 1978 data.
The seismic accuracy of the intermediate soil stratigraphy
is not as good, since the principal objective of the sur-
veys was to 1 ocate top-of-bedrock. Therefore, the survey
technique used was not conducive for accurately detailing
the intermediate zones. As a result, the stratigraphy
within the channel has been based on very preliminary and
widely scattered data point (Figure 6.40).
The following sections provide a detailed discussion of the
Watana relict channel.
6-32
.~
(; ; )
( i; i )
-
-
Location and Configuration
The approximate location of the relict channel is shown on
photographs in Figure 6. 30. The upstream entrance to the
channel extends from a location approximately 2,000 feet
upstream from the damsite, where bedrock drops below maxi-
mum pool elevation (2202 feet), to a point more than two
miles upstream from Deadman Creek.
The ground surface in the relict channel is flat to gently
rolling with a drainage divide trending generally north to
northeast through the area which closely corresponds with
seismic lines DM-A and DM-B (Figure 6.31).
A top-of-bedrock contour map showing surface topography and
projected flow paths through the channel are shown in
Figure 6.35. The maximum overburden thickness in the thal-
weg channel is approximately 450 feet.
A sketch showing the relict channel with and without the
overburden removed is shown in Figure 6.30. Under the max-
imum operating pool level of 2,185 feet, a total of approx-
imately 13,500 feet of the upstream portion of the channel
would be inundated with water (Figure 6.31).
The distance between the proposed reservoir and Tsusena
Creek along the shortest distance through the channel would
be approximately 6,200 feet and 7,700 feet along the thal-
weg section (Figure 6.33).
An average hydraulic gradient along the thalweg would be
about 1:14.
Geology
The formation of the relict channel and the subsequent div-
ersion of the Susitna River into its present position is
likely the result of a sequence of glacial events during
the Quaternary Period (Table 4.1).
The Quaternary history of this area is very complex and
poorly understood. However, based on work performed by
Acres and Woodward-Clyde Consultants (60) during this
study, the following geologic events appear to be the most
plausible in explaining the existing conditions.
During preglacial times, the Susitna River flowed down the
relict channel and into the area of Tsusena Creek. The
river in this area followed the path of least resistance,
being diverted around the more massive diorite ~luton
(which underlies the dams it e) to the south. The relict
6-33
channel appears to have followed the softer sheared and
fractured rock of "The Fins" structure which is traced
through this area (Section 6.1).
Advancement of the Tsusena Creek glacier into this area
from the north and northeast resulted in the infilling and
diversion of the Susitna River to the south around the ice
margin, where it subsequently downcut through the diorite
along existing joint sets (Section 6.1). Once below ap-
proximate Elevation 1900, the river fell below the entrance
to the relict channel. Several glacial advances and
retreats through this area resulted in deposition of a
thick sequence of glacially derived materia 1 within the
relict channel. This material consisted of basal till,
alluvium, glacial fluvial silts, sands, and gravels and
lacustrine clays.
The actual time and number of glacial advances and retreats
in this area are unknown. However, this sequence of events
appears to be supported by the stratigraphy within the
relict channel.
(iv) Stratigraphy
Based on the drilling in, and adjacent to, the relict chan-
nel, a total of 11 stratigraphic units have been identi-
fied. They have been designated by 1 etters A through K.
These units have been differentiated based on texture,
structure, color, mode of deposition and stratigraphic pos-
ition. Although facies changes exist in these units, each
represents a unique depositional event. The correlation of
the deeper units have been based principally on the eight
deep holes drilled by the COE (45). Since these holes were
drilled over a large area, additional work will be neces-
sary to confirm these units and their extent. A vertically
exaggerated cross section showing these stratigraphic units
is presented in Figure 6.33. This section corresponds with
the true section shown in Figure 6.31.
These stratigraphic units are discussed below with a
detailed stratigraphic column presented in Figure 6.32.
Table 6.7 provides a summary of the unit•s thickness, type,
occurrence, and permeability.
-Unit K
An alluvial deposit, designated as Unit K, is the oldest
and deepest Quarternary deposit found in the relict chan-
nel area. This unit was only encountered in one borehole
at a depth of 292 feet (DR-22). The unit, which is 162
6-34
r
-
-
r
-
feet thick overlies bedrock, it is composed of boulders,
cobbles, and gravels. Increasing amounts of fine materi-
al are present in the upper horizons of the unit. Unit K
appears to be an extremely dense a.ll uvi um that was de-
posited within the main thalweg of the relict channel,
prior to glaciation. No other evidence of this unit was
found in the relict channel area.
-Unit J
A dense till, designated as Unit J, is the oldest glacial
deposit in the relict channel area. This till generally
overlies bedrock, except in the thalweg of the relict
channel, where it overlies the older alluvium of Unit K.
This till is distinguished by poorly sorted subangular
silts, sands,_ gravels, and cobbles which are highly com-
pacted as a result of being overridden by later ice
advances. Hematite and limonite staining is common in
the unit. The unit appears to follow the topography of
the underlying bedrock surface reaching its maximum
thickness in the relict channel of approximately 60 feet
(Figure 6.33). "
Unit J' is a localized clean sand and gravel fluvial
deposit that is up to 45 feet thick. The unit is distin-
guished by its clean, sorted, rounded particles and high
permeability. Water losses in excess of 50 gallon/feet
were noted during drilling of this unit. This unit,
which likely represents an interglacial outwash and allu-
vium, is found only in the relict channel thalweg.
-Unit I
Another till, designated Unit I, overlies Units J and J'.
This till, is very similar in texture, composition, den-
sity, and color with the underlying Unit J, making dis-
tinction between the units difficult. The only noted
difference is that Unit J is marked by a 2-to-6-inch
layer of sand or silt within the middle of the unit. The
average thickness of this unit where drilled is 60 feet.
Unit H
Unit H is a series of alluvial and outwash deposits which
represent a period of interglacial melting. This unit,
which is found as channel deposits in topographic lows of
Borrow SiteD, becomes thicker and more continuous in the
buried channel. Unit H likely represents the horizontal-
ly discontinuous remnants of an outwash plain cut by
6-35
alluvial channels. Thickness of the unit in the channel
reaches a maximum of 40 feet. Particles are generally
sorted and sub-rounded to rounded gravels and sands,
which are moderately permeable (Figure 6.33).
-Unit G
Unit G marks another glacial advance. This unit contains
greater amounts of fine material than the other units.
In some areas, the material is plastic, containing a
large portion of clay size particles with varied lacus-
trine deposits. Gravel and sand usually are present,
often with ice-rafted cobbles and boulders. Such materi-
al is typical of tills deposited by either floating ice
or in water that is in contact with the ice margin.
Other areas have rounded to sub-angular poorly sorted
silt, sand, gravel, and cobbles, which are typical of
basal glacial tills. Unit G reaches a maximum thickness
of 65 feet.
-Units C, E, and F
A final retreat of the ice in this area is marked by lay-
ers of outwash, designated units C, E, and F. These
units, which are similar to each other, contain varying
amounts of partially sorted and rounded cobbles, gravels,
sands, and silts. These units can be distinguished prin-
cipally through their stratigraphic position. Permeabil-
ity of these units is generally low to moderate, because
of the presence of varying amounts of fines. Since these
units were deposited as glacial outwash, they tend to
fill in topographic lows and smooth the topography. The
upper horizon of the outwash, Unit C, is often absent,
possibly having been removed by post-glacial erosion in
many areas. Thickness of the outwash in the buried chan-
nel area reaches a maximum of 75 feet.
-Unit D
Unit D occurs locally as well-sorted alluvial, sands,
silts, and gravels between outwash C and E. This materi-
al in fills channels cut into the outwash surface of Unit
E. These channels generally trend southward across the
area, toward the present Susitna River. The thickness of
these channels is approximately 15 feet.
6-36
-
-
r
-i
-'
Units A and B
Near surface deposits confined to the upper few feet of
Unit D are mainly cobbles raised by frost action and or-
ganic tundra material (Unit A) in a silty sand matrix
(Unit B). These two units are not present in significant
thickness and, therefore, have not been shown on the sec-
tions.
Based on the stratigraphy presented above, it appears
that the relict channel has been overrun by a minimum of
two and possibly three glacial advances (Units J, I, and
C). Interglacial periods are marked by varying thick-
nesses of glaciofluvia1 and paraglacial silts, sands, and
gravels with occasional cobbles (Units J•, H, C, E. F. 0,
A, and B).
This glacial sequence indicates that Units I through K
have been overridden and consolidated by subsequent glac-
i a 1 readvances.
(v) Groundwater
The groundwater regime in the relict channel is complex
because of the presence of intermittent permafrost, a qui-
eludes, perched water tables, and confined aquifers. There
are i nsuffi ci ent data to fully document the groundwater
conditions in this area; however, the following presents
what is currently known regarding the regime. Further
detailed investigations will be required to accurately
determine the number, extent, flow directions, and perme-
abilities within the various aquifers.
The relict channel lies within the drainage between Deadman
Creek to the east, the Sus itna River to the south. and
Tsusena Creek to the west and northwest. Groundwater grad-
ients in the unconsolidated sediments of the channel are
principally towards Tsusena and Deadman Creeks with the
diorite pluton at the damsite acting as a groundwater bar-
rier to the south.
Most of the test pits and auger holes drilled and excavated
in the relict channel and Borrow Site D (Section 6.3) en-
countered water within the upper 10 feet. Those holes that
did not encounter water were either in solid frost or in
the coarser permeable gravels of Units C through F. The
near surface water table appears to be perched on top of
the impervious or semipervious Unit G. Therefore, this
shallow water table likely reflects the upper seasonal thaw
surface overlying this unit.
6-37
fm
Artesian conditions were encountered in Unit H suggesting
that it is being confined below the low permeable Unit G.
Highly permeable zones were encountered in Units J' and K
at depths of 208 to 231 feet and 293 to 375 feet, respec-
tively (DR-22) (Figure 5.1).
In summary, the principal water bearing units within the
relict channel appear to be in Units C, D, H, J', and K.
The actual permeabilities of these units, however, have not
been determined.
(vi) Permafrost
Intermittent permafrost in the relict channel area is evi-
dent by localized frost-heave features, cobble paving and
isolated spruce cover.
The extent of permafrost within the relict channel and Bor-
row Site D has been determined by dr i 11 i ng records and
thermistor instrumentation installed in various boreholes
drilled by the COE and Acres (Tables 3.2 and 5.4 and Figure
5.1). Thermistor readings are presented in Figure 6.28.
Drilling performed by the COE showed only sporadic perma-
frost in the relict channel area. Borings AP-1 and 2,
DR-16 through DR-20 and DR-22 did not show excess amounts
of permafrost; whereas borings DR-18 and DR-22 encountered
permafrost in Units G and H at depths of 20 to 68 feet and
72 to 110 feet, respectively (Figure 6.33). Thermistor
data in these holes show freezing temperatures from approx-
imately 60 to 140 feet below ground surface in both holes.
Permafrost was encountered in 28 of the 44 auger hales
drilled in Borrow Site D. Many of these holes showed sea-
sonal frost from near ground surface to approximate depth
of 7 feet, with permafrost being encountered from around 12
to 20 feet. However, several holes showed continuous
frost/permafrost to the full depth drilled (Appendix F).
No visual ice or excess water (upon thawing) was found
within any of the dri1led holes below 25 feet. This lack
of free ice below 25 feet is supported by the moisture con-
tents of this material, which is near optimum (12 to 14
percent (Section 6.3[d]). The deepest permafrost encounted
in the relict channel was at a depth of 240 feet in DR-22
(Figur'e 5.1). However, the deepest continuous permafrost
was about 30 to 40 feet.
6-38
-l
-I
-
-
I"""
t
-
(b)
The temperatures in the relict channel are fairly uniform
with temperatures in the thalweg segment of the channe 1
being close to l°C. Slightly higher temperatures were mea-
sured in DR-22 in the more permeable units of H and J 1 dur-
ing the initial reading (Figure 6.28). This likely
reflects an unstable temperature condition caused by drill-
ing fluid that was injected into this zone.
Temperature readings in Borrow Site D (Figure 6. 28) show
temperatures near 1 to 2°C, suggesting a marginal perma-
frost condition. However, most of these thermi stars were
installed in the summer/fall of 1981 and, as is common in
11 Warm" permafrost, they have not fully stabilized over such
a short time period. Future rep.dings will likely show a
shift towards cooler temperatures.
Fog Lakes 11 Relict" Channel
( i ) I ntrod uct ion
( i i )
Other areas around the dams ite and within the reservoir
were investigated during the 1980-81 program to determine
whether other buried channels existed that could potential-
ly affect reservoir impoundment.
A complete review of site and regional geologic mapping,
reservoir mapping, and airphoto interpretation showed that
the only potential buried channel(s) which might be inun-
dated by the Watana Reservoir (other than the Watana Relict
Channel (Section 6.2 [a]) is in the area between Quarry
Site A immediately upstream from the damsite and Fog Lakes
approximately five miles to the east.
In 1981, a 24,000-foot seismic refraction line was run in
this area to determine the top-of-rock. Details of this
survey are presented in Appendix I. The following sections
briefly summarize the results of that survey and the poten-
tial impacts of this area to the project.
Location and Configuration
The location of the seismic line performed in this area is
shown in Figure 1 -Appendix I.
The minimum surface elevation along the line is approxi-
mately 2280 feet, nearly 80 feet above Maximum Pool Eleva-
tion of 2202 feet.
For discussion, the bedrock surface, as shown along the
seismic lines, can be divided into 3 sections: the west
section, central section, and east section.
6-39
The west section of the line extends from the rock outcrop
south of Quarry Site A eastward along the line for approxi-
mately 2,000 feet. Here, the bedrock surface appears to be
a series of ridges and valleys with the deepest bedrock
reaching Elevation 2025 or 175 below maximum pool level.
The central section continues for approximately 2 miles
easterly. Bedrock in this area is relatively shallow and
generally flat to slightly undulating.
Along the western portion of the line in the Fog Lakes
area, bedrock drops off rapidly to depths up to 350 feet
until it again shallows along the east edge of the line.
The total estimated width of bedrock below maximum pool
level along this line is estimated to be about 2,400 feet
a 1 ong the west section near Quarry Site A and 7,100 feet
along the east section in the Fog Lakes area.
(iii) Geology
Since no subsurface drilling was performed in this area,
soi 1 and rock types and depths to bedrock have been in-
ferred based solely on seismic velocity measurements.
Woodward-Clyde Consultants delineated three genera 1 types
of soils in this area: (a) a poorly consolidated, satur-
ated glacia1 deposit; (b) a well-consolidated glacia1 sedi-
ment which may be partial1y frozen; and (c) an intermittent
surficial material ranging up to 50 feet thick.
Several areas along the traverse appear to be buried chan-
nels which extend below the proposed reservoir level. The
two most prominent areas are near the west end of the tra-
verse and. beneath the Fog Lakes Valley (Figures 17, 22. 23
of Appendix I).
The shape of the channel shown on the profile has been con~
serva.tive1y estimated based on marginal arrival time data
from distant offsets and from minimum depth calculations.
A number of tmtt>rtaint.i•2S exist in the interpretation. par-
ticularly the natw·e of the 8,000 to 11~000 fps apparent
channel fill material. This material could either per-
mafrost~ overcanso~idated till. or weathered rock. Future
investig:rtions ~in this area rna.Y b~~ ~;\r~rre~r;ted to d~~termine
the nature of ·[ s materia 1 and the actu~ 1 exi st.ence of a
buried va11ey,
6-40
r---\
-!
r
-
-
( i v)
(v)
Groundwater
The groundwater table in the area appears to be relatively
shallow, as evidenced by poor surface drainage and numerous
ponds, lakes, and bogs. Drainage of the area is toward the
Susitna to the north and Fog Creek, nearly 5 miles, to the
south. Groundwater gradients are expected to be steep in
the Susitna drainage area and very low {<1 percent) toward
Fog Creek.
Permafrost
Permafrost conditions are likely to be sporadic throughout
the area, as evidenced by the existence of typi ca 1 perma-
frost features to include black spruce, hummocky tundra,
perched ponds on hills, and skin flows.
6.3 -Borrow and Quarry Material
The borrow and quarry materials investigation at Watana was directed
to:
-further investigate the quantity and material properties of borrow
and quarry sources i dent i fi ed in previous studies, and
-locate new potential source areas for those materials considered to
have either insufficient reserves or questionable production feasi-
bility 0
A total of seven borrow sites and three quarry sites have been identi-
fied for dam construction material (A, B, C, D, E, F, H, I, J, and L)
{Figure 6.36). Of these, Borrow Sites D and Hare considered as poten-
tial sources for semipervious to pervious material; Sites C, E, and F
for granular material; Sites I and J for pervious gravel; and Quarry
Sites A, B, and L for rock f"fl 1.
Several of these sites (B, C, and F), previously identified by the COE,
were not considered as primary sites for this study because: (1) a
more locally available source of material to the damsite; (2) adverse
environmental impacts; (3) insufficient quantity; or {4) poor quality
of the material. Therefore, no work was performed in these areas dur-
ing 1980-81. These sites, however, have not been totally eliminated
from consideration as alternative sources and are therefore included in
this discussion.
Since adequate quality and quantity of quarry rock are readily avail-
able adjacent to the damsites, the quarry investigation was principally
limited to general field reconnaissance to delineate boundaries of the
quarry sites and to determine approximate reserve capacity. This al-
lowed for a more detailed investigation in the borrow sites.
6-41
The borrow investigations consisted of seismic refraction surveys, test
pits, auger holes, instrumentation, and laboratory testing. The re-
sults of this study are discussed below.
Each site is presented in the following sequence:
(i) Proposed use of the material and why the site was selected;
(ii) Location and geology, including topography, geomorphology, vege-
tation, climatic data, groundwater, permafrost, and strati-
graphy;
(iii) Reserves, lithology, and zonation; and
(iv) Engineering properties which include index properties and labor-
atory test results.
(a) Quarry Site A
(i) Proposed Use
Quarry Site A is a large exposed diorite and andesite por-
phyry rock knob at the south abutment of the Watana damsite
(Figure 6.35). The predominant rock type is diorite. The
proposed use for the quarry is for blasted rockfill and
riprap.
Quarry Site A was selected based on its apparent good rock
quality and close proximity to the damsite.
(ii) Location and Geology
The boundaries of Quarry Site A include the bedrock "knob"
from approximate Elevation 2300 to about 2600 (Figure
6. 37). The knob covers an area approximately one square
mile. Glacial scouring has gouged out east-west swales in
the rock (Figure 6.37). These swales likely corresponded
with fractured, sheared, and altered zones within the rock
body. Overburden ranges from 0 to several feet over the
site. Vegetation is 1 imited to scrubby spruce, vines, and
tundra, with limited alder growth in the lower areas. Sur-
face water is evident only in isolated deeper swales.
Based on information presented in Section 6.1(g), the
groundwater table is expected to be deep in this area with
an estimated average depth to the water table from 50 to
100 feet. It is likely that the groundwater level will be
near the quarry floor during operation, but inflows are
expected to be small, diminishing with time.
6-42
~~·
-!
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-
( i i i )
Although no borings have been drilled in this site, it is
likely that permafrost will be encountered as shallow as 5
feet in depth. The permafrost, however, is near the thaw
point (see Section 6.2[h]) and, because of the high expo-
sure to sunlight in this area, is expected to dissipate
rapidly. The permafrost zones are expected to be more com-
mon in the more fractured and sheared zones.
The western portion of the site has been mapped as sheared
andesite porphyry (Figure 6.37) with the remainder of the
site being gray diorite. Mapping on the northern half of
the site in 1980-81 showed the rock to grade between black
andesite porphyry and a coarse-grained gray andesite with
sections grading into diorite. Despite these lithologic
variations, the rock body is relatively homogeneous. Based
on airphoto interpretation, severe shearing and alteration
appear to be present on the northeast corner of the deline-
ated site area.
Reserves
The limits denoted in Figure 6.37 are conservatively drawn
to include all exposed or partially covered rock which com-
prises approximately 530 acres. Extension of these limits
would likely include areas of deeper overburden. The depth
of severe weathering is estimated to be an average of 5 to
10 feet.
The rock exposure in Quarry Site A provided adequate confi-
dence in assessing the quality and quantity of available
rockfill necessary for feasibility. Allowing for spoilage
of poor quality rock caused by alteration and fracturing,
and assuming a minimum bottom elevation of 2300, the esti-
mated volume of sheared or weathered rock is 23 million
cubic yards (mcy) and 71 mcy of good quality rock.
Additional rock fill, if required, can be obtained by deep-
ening the quarry to near the proposed dam crest elevation
of 2210 without adversely affecting the dam foundation or
integrity of the reservoir.
(iv) Engineering Properties
Weathering and freeze-thaw tests were conducted to deter-
mine the rock • s resistance to severe environmenta 1 condi-
tions. Results indicate that the rock is very resistant to
abrasion and mechanical breakdown, seldom losing strength
or durability in presence of water and demonstrating high
resistance to breakdown by freeze-thaw.
6-43
Since this rock is of the same parent rock as the damsite,
its physical and mechanical properties are expected to be
similar to those results presented in Section 6.1(e). The
rock is expected to make excellent riprap, rock shell, or
road foundation material.
(b) Quarry Site B
{i) Proposed Use
Quarry Site B was identified in previous investigations as
a potential rock quarry for dam construction {Figure 6.36
and 6.38). The area was identified based on outcrops ex-
posed between Eleva,tions 1700 and 2000 along the Susitna
River and Deadman Creek. During 1980-81 field reconnais-
sance, mapping and additional seismic refraction surveys
were performed in this area.
(ii) Location and Geology
Quarry Site B is 1 ocated about two m·J l es upstream from the
damsite between Elevations 1700 and 2000. This area ini-
tially appeared economically attractive because of the
short-haul distance and 1 ow-haul gradient to the dams it e.
However, geologic mapping and seismic refraction surveys
performed in this area indicate that the rock is inter-
fingered with poor quality sedimentary volcanic and meta-
morphic rocks (Figure 6.38) with thick overburden in sev-
eral areas (Appendices Hand I).
Vegetation cover is heavy, consisting of dense alder
marshes and alder with aspen and black spruce in the
higher, drier areas. The entire south-facing side of the
site is wet and marshy with numerous permafrost features.
The quarry side facing Deadman Creek is dry, with thick
t i 11 overburden, which appears frozen. Permafrost in the
area is expected to be continuous and deep. Surface runoff
from Borrow Site D (Section 6.3 [d]) flows southward pass-
ing through Quarry Site B.
(iii) Reserves
Because of (a) the deep overburden (as evidenced by seismic
lines SL81-18 and 19); {b) generally poor rock quality; and
(c) the extreme vegetation and topographic relief, Quarry
Site B was not considered as a primary quarry site. There-
fore, no reserve quantities were determined for feasibil-
ity.
6-44
( i v)
-[
(c) Borrow
F"" ( i )
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( i i )
( i i i )
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'
Engineering Properties
No material property testing was performed for this area.
Site C
Pro~osed Use
Borrow Site C was identified in previous studies as a pos-
sible source of gravels and sands for filter material (45).
Previous explorations in Borrow Site C consisted of three
seismic refraction lines and one test pit (39). The 1980-
81 investigation identified adequate volumes of granular
material much closer to the damsite in Borrow Site E (Sec-
tion 6.3[e]). Therefore, no additional work was performed
in this area during this study.
Location and Geology
Borrow Site C, as delineated by the COE, extends from a
point approximately 4-1/2 miles upstream from Tsusena Butte
to the northwest toe of the butte (see Figure 6. 39). As
seen from the photo on Figure 6.39, the site is a broad
glacial valley filled with till and alluvium. Vegetation
ranges from alpine tundra on the valley walls to heavy
brush and mixed trees at the lower elevations, thinning to
mixed grass and tundra near the river and on terraces. The
groundwater table is assumed to be a subdued replica of the
topography, being shallow on the valley walls with grad-
ients towards the valley floor. Groundwater migration is
expected to be rapid through the highly permeable alluvial
material. Permafrost may be intermittent.
Based on the test pit and a seismic refraction survey, the
stratigraphy appears to consist of over 200 feet of basal
till overlain by outwash, and reworked outwash a 11 uvi um.
The upper 100 to 200 feet of material is believed to be
saturated gravels and sands.
Reserves
Because the site is not currently being considered as a
borrow source, no detailed quantity estimate has been made.
However, assuming an approximate area of 1,500 acres and an
excavation depth of 15 feet above water table, a gravel
quantity on the order of 25 mcy can be approximated. Addi-
tional quantities may be obtained at depth; however,
further studies will be required to determine the volumes.
6-45
(iv) Engineering Properties
The test pit and reconnaissance mapping show the material
in the floodplain and terraces to be a 4-inch minus, well•
washed gravel with approximately 60 percent gravel, 40 per-
cent sand, and negligible fines. The gradations are repre-
sentative of a clean, well-washed material with a percen-
tage of cobbles and fines at depth.
(d) Borrow Site D
(i) Proposed Use
Borrow Site D was identified in 1975 as a potential primary
source for impervious and semipervious material by the
CO E.
Based on the field studies performed by the COE in 1978
(45), it was tentatively concluded that:
-Borrow SiteD had potentially large quantities of clay
and silt;
-The deposit was of adequate volume to provide the esti-
mated quantity of material needed for construction; and
-The site had favorable topography and hydrology for bor-
row development.
As a result of these previous studies, Borrow Site D became
a primary site for detailed investigation during the 1980-
81 study.
(ii) Location and Geology
Borrow SiteD lies on a broad plateau immediately northwest
of the Watana damsite. The southern edge of the site lies
approximately 1/2 mile northeast of the dam 1 imits and
extends eastward towards Deadman Creek for a distance of
approximately 3 miles (Figure 6.40). The topography slopes
upward from the dams i te e 1 evat ion of 2150 northward to
approximate Elevation 2450.
The ground surface has localized benches and swales up to
50 feet in height. The ground surface drops off steeply at
the slopes of Deadman Creek and the Susitna River.
As noted in the site photographs shown in Figures 6.30 and
6.40, vegetation is predominantly tundra and sedge grass
averaging about one foot thick with isolated strands of
spruce trees on the higher and dryer portions of the site.
6-46
-I
r
I
I
l
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-!
I"""'
I
-!
(iii)
Climatic conditions are similar to those at the damsite
with the exception that the borrow site is more exposed to
higher winds and sunlight. The relatively open rolling
topography is conductive to drifting and blowing snow, fre-
quently resulting in drifts up to six feet deep.
Surface water and groundwater conditions have been ad-
dressed in detail in Section 6.2 -Watana Relict Channel.
In summary, the northwest portion of the site has numerous
lakes and shallow ponds with the remaining portions of the
site having localized standing water perched on either per-
mafrost or impervious soils. Surface runoff is towards
Deadman Creek to the northeast and Tsusena Creek to the
west. Generally, much of the area is poorly drained, with
many of the low-lying areas wet and boggy.
Instrumentation installed throughout the borrow site shows
intermittent "warm" permafrost. Temperatures in the perma-
frost zones are all within the -l°C range. Detailed dis-
cussions of permafrost as it relates to specific strati-
graphic units within the area have been addressed in Sec-
tion 6.2. Thermistor plots (Figure 6.28) show annual frost
penetration of approximately 15 to 20 feet. Annual ampli-
tude (fluctuation) in ground temperature reaches depths of
20 to 40 feet. The greatest depth of temperature amplitude
is in the unfrozen holes, while the permafrost holes reach
20 to 25 feet. This may be caused by either the effect of
possibly greater water content at the freezing interface
lessening the seasonal energy variations or the thicker
vegetation cover in the permafrost area causing better in-
sulation.
Detailed discussion of the borrow site geology are present-
ed in Section 6.2. The distribution of the various strati-
graphic units within the borrow site are shown in Figure
6. 32.
Reserves
The boundaries of the borrow site, as shown in Figure 6.40,
are somewhat arbitrary, being limited on the south side by
the apparent limit of undisturbed material, to the east by
Deadman Creek; to the northwest by low topography; and to
the north by shallowing bedrock. If further studies indi-
cate the need for additional materials, it may be feasible
to extend the borrow site to the northwest and west. Fac-
tors to be considered in borrow site expansion are:
6-47
Siting of other facilities in this area;
-Impacts on relict channel;
-Haul distance; and
-Environmental impacts.
The reserve estimates for Borrow Site 0 have assumed an
average material thickness throughout the site limits
(Figure 6.40). Based on the currently established boundar-
ies (encompassing about 1,075 acres) and an excavation
depth of 120 feet, a total of 200 mcy of material is avail-
able.
(iv) Engineering Properties
The laboratory tests performed on materials from Borrow
Site 0 are presented in Appendix F. A tabulation of the
samples collected and the test results are presented in
Table 6.8.
Grain size distribution within the borrow site ranges from
coarse gravels to clay, as shown in the composite grain
size curves (Figure 6.41). Groupings of the various soil
types are shown in Figure 6.42. Soil gradations, as relat-
ed to the stratigraphic units within the borrow site (Sec-
tion 6.2), are shown in Table 6.9. As can be seen in
Figure 6.41, almost all of these samples are well graded,
ranging from gravel to fine silt and/or clay. Only Unit H
(Section 6.2) exhibits a different characteristic, being a
more uniform fine sand and silt. Moisture contents range
from a 1 ow of 6 percent to a high of 42.5 percent with an
average of approximately 14 percent. The highest moisture
contents are found in Unit G, a fine gray clayey material
(Section 6.2).
Atterberg 1 imits show the soil to fall into two basic
groups. The first, consisting of Units C, D, E, and F, are
basically non or slightly plastic material. The Liquid
Limits of these soils are close to their natura 1 moisture
content, varying from 13 to 17 percent. These tests are
consistent with previous tests by the COE which show the
material to be non plastic or slightly plastic in nature.
The plasticity index varies from non plastic (NP) to 2.
The second group, comprising soil units G, I, and J, have
liquid limits ranging from17 to 39 percent with plasticity
indices ranging from NP to 15 with an average of 10.
Specific gravity for the material is 2. 71, which is within
an expected range for these soi 1 s. Permeabi 1 ity tests on
samples compacted to Modified and Standard Proctor values
at 2 percent above optimum moisture content gave permeabil-
ities on the order of 10-6 em/sec.
6-48
.....
-
-
-
Compaction of a composite sample from Borrow Site D was
undertaken utilizing both Standard and Modified Proctor
Compaction procedures. The Standard Proctor Test (material
<No. 4 sieve) shows the material to have a maximum dry den-
sity of about 128 pcf at an optimum moisture content of
10.4 percent. Modified Proctor Test results (material <3/4
inch sieve) indicate a maximum dry density of 135 pcf at
7.5 percent moisture.
Modified and Standard Proctor compaction at 2 percent above
optimum moisture content give consolidation compressive
indices (Cc) of 0.061 and 0.091, respectively.
Shear strength tests give an angle of internal friction (~)
of 37 degrees, which corresponds with previous COE data •
Pinhole dispersion tests indicated the material to be non-
dispersive.
(e) Borrow Site E
(i) Proposed Use
( i i)
Borrow Site E (Figures 6.43 and 6.36) was identified by the
COE as a principal source of concrete aggregate and filter
material for the Watana dam. The apparent volume of mater-
ial and its close proximity to the site made it the primary
site for detailed investigations during the 1980-81 pro-
gram.
Location and Geology
Borrow Site E is 1 ocated three miles downstream from the
damsite on the north bank at the confluence of Tsusena
Creek and the Susitna River (Figure 6.43). The site is a
large flat alluvial fan deposit which extends for 12,000
feet east-west and approximately 2,000 feet northward from
the Susitna River up Tsusena Creek. Elevation across the
site varies from a low of 1410 near river level to 1700
where the all uvial and terrace materials 1 ap against the
valley walls to the north (Figure 6.43).
The area is vegetated by dense spruce and some alders, tun-
dra, and isolated brush. Vegetation cover averages about
one foot thick underlain by up to four feet of fine silts
and volcanic ash.
Groundwater was found to be generally greater than 10 feet
deep. Groundwater levels fluctuate up to five feet from
winter to summer, indicating a free draining material.
6-49
The hydrologic regime shows summer peak flows in the area
reaching approximate Elevation 1435-1440 at the north of
Tsusena Creek. This elevation corresponds with the limit
of scoured and unvegetated river bank. The estimated 50-
year flood level is approximately 1,473 feet.
Figure 6.53 presents a generalized stratigraphic section
through the borrow site showing the underlying bedrock
overlain by a sequence of bouldery till, river and flood-
plain gravels and sands. As in the case of Borrow Site D,
the grain size distribution in Site E varies from boulders
to fine silt and clay (Figure 6.45). Within this wide
range of soil types, five distinct soil gradations (A
through E) can be delineated (Figure 6.46). However, the
complex depositional history and the limited exploration
performed in this area does not allow for ready correlation
of these soil types over the site. Generally, however, the
finer silts and sands are found in the upper five feet of
the deposit. As noted in the typical sections (Figures
6.43 and 6.53), several abandoned river channels of either
the Tsusena Creek ·or the Susitna River cross cut the site.
The infilling and cross cutting of these streams and rivers
through the site has resulted in a complex heterogeneous
mixing of the materials. Exploration indicates that,
although the five principal soil types are persistent with-
; n the site, they vary in depth from near surface to
approximately 40 to 70 feet.
No permafrost has been encountered in the borrow site, pro-
bably because the site has a south-facing exposure and has
a continuous thawing effect caused by the flowing river.
Seasonal frost, up to 3 to 6 feet deep, was observed in
test pits that encountered groundwater (mid-March 1981) and
up to at least 13 feet in pits on the northwest side of the
site that did not intercept the groundwater table. In
areas of shallow groundwater, the frost was almost exclu-
sively confined to the upper shallow sand and silt layers,
while dry gravels showed deeper frost penetration. Annual
frost penetration may be assumed to be about 3 to 6 feet in
silty or clayey soils and at least 11 feet in loose dry
gravels.
(iii) Reserves
Quantities were calculated on the basis of known and
inferred deposits above and below the current river regime.
Assuming an over a 11 surface area of approximately 750 to
800 acres, the estimated quantity of material above river
elevation is 34 mcy. An additional volume of 52 mcy is
available below river elevation (Figure 6.44) assuming a
total maximum depth of excavation of 125 feet in the
6-50
~'
~I
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(f)
southwest corner of the borrow site, decreasing to a mini-
mum of 20 feet in the northeast corner.
Approximately 80 percent of the identified material in the
borrow site is within the floodplain area, 10 percent in
the hillside terraces, and 10 percent in the Tsusena Creek
segment.
Average stripping is estimated at one foot of vegetation
and three to four feet of fine grained material.
(iv) Engineering Properties
A summary of the samples and laboratory tests performed on
selected materials from Borrow Site E are shown in Table
6.10. Details of the laboratory testing are provided in
Appendix F. The soil units A through E range from coarse
sandy gravel through gravelly sand, silty sand, cobbles and
boulders, silty sand and silt (Figure 6.46). Several of
these material units correlate well with the material in
Sites I and J (Sections 6.3[h]). Moisture contents for the
silts range from 25 to 30 percent; sand from 4 to 15 per-
cent; and gravels from 1 to 5 percent. The percentage of
material over 6 inches is roughly estimated at 10 percent
with the over-12-inch estimated at 5 percent.
Selective mining may be possible to extract particular
types of material. Further detailed investigations in this
area will be required to accurately define the location and
continuity of stratigraphic units.
Borrow Site F
(i) Proposed Use
Borrow Site F was identified by the COE as a potential
source of filter material for the main dam. Preliminary
work performed by the COE showed the site to have 1 imited
quantities of material spread over a large area. For this
reason, Borrow Site E became the preferred site, with Bor-
row Site F being considered as an alternative source for
construction material for access roads, runways, and camp
~ construction. No work was performed in this area during
: the 1980-81 program.
-
!"""
I
(ii) Location and Geology
Borrow Site F occupies the middle stretch of Tsusena Creek
from just above the high waterfall to north of Clark Creek
where it abuts Borrow Site C {Figure 6.39). The northeast
portion of the valley is confined by the flank of Tsusena
6-51
Butte and its talus slopes. The vegetation in the area is
mixed spruce and tundra, with isolated areas of undergrowth
and alders. Groundwater is expected to be near surface.
Limited permafrost is 1 ikely to be encountered in north-
and west-facing exposures but is expected to thaw readily
when exposed during summer months. Deposits above stream
level are expected to be fairly well drained with lower
areas saturated.
Limited test pits indicate the material in Borrow Site F is
the same as that in Borrow Site C (Section 6.3 [c]). The
depth of clean sands and gravels is estimated to be approx-
imately 20 to 30 feet, ranging from a shallow 5 feet to a
maximum of 40 feet. The area consists of a series of
gravel bars and terraces extending up to 1,500 feet away
from the stream (Figure 6.39).
(iii) Reserves
No detailed topography was obtained for the site; however,
assuming a conservative depth of 20 feet of material, a
total volume of approximately 15 to 25 mcy is likely avail-
ab 1 e.
Additional investigation in this area will be required to
confirm these volumes.
(iv) Engineering Properties
Test pits excavated by the COE (Figure 6.39) show gravelly
sand overlain by a very thin silt and sandy silt cover. A
composite gradation curve for material in this site is
shown in Figure 6.47. No detailed testing was performed on
this material.
(g) Borrow Site H
(i) Proposed Use
Borrow Site H was defined during the 1980-81 field investi-
gation as an alternative site to Borrow Site D for impervi-
ous and semipervious material.
(ii) Location and Geology
The topography of Borrow Site H is a generally rolling,
sloping towards the Susitna River. Elevations range from
1400 to 2400 across the site and average about 2100 (Figure
6.48). Most of the site is covered by swamps and marshes,
indicating poor drainage. The vegetation consists of thick
tundra, muskeg, alder, and underbrush growth.
6-52
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-i
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(iii)
Groundwater and surface water are perched on top of imper-
vious material with numerous seeps and ponded surface
water. The extensive coverage of spruce trees may be indi-
cative of a degrading permafrost area. A large ice deposit
exists in a slump exposure on the west end of the site.
The deposit and associated solifluction flow with a multi-
ple regressive headwall are approximately 100 to 150 feet
across and are visible in the photo (Figure 6.48).
Of the eight auger holes drilled in the site, six encoun-
tered permafrost at depths ranging from 0 to 14 feet in
depth. All the holes but one showed the water table at or
near the surface (Appendix F, Figure 6.48). All of the
borings had temperature probes installed during the 1981
program; however, the instruments have not yet stabi 1 i zed
(Figure 6.29). Future readings are likely to show a cool-
ing in the temperature plots.
The site stratigraphy consists of an average of 1.5 feet of
organics, underlain by 1. 5 to 4.5 feet of brown sand or
silt material with traces of organics. Below this upper
material, most of the holes show mixed silt, sandy silt,
and sandy clay to depths of 6 to 13 feet, which in turn is
underlain by zones of gravels, gravelly sand, and mixed
silts with sand and gravel. A color change from brown to
gray occurs at depths of 6 to 28 feet. Insufficient data
exist to allow for detailed stratigraphic correlation
across the site.
Reserves
The quantity estimate has assumed a relatively homogeneous
mix of material over a surface area of 800 acres, with 5.5
feet of stripping required to remove organics and clean
silts and sands. Assuming an estimated usable thickness of
32 feet (based on dr i 11 i ng data) approximately 35 mcy of
material is available from this site.
(iv) Engineering Properties
A summary of the samples and laboratory test results from
materials from Borrow Site Hare shown on Table 6.11. Lab-
oratory test results are contained in Appendix F.
A composite gradation for the borrow site is shown in
Figure 6.49. A detailed assessment of the grain size dis-
tribution shows three distinct gradation groupings (A
through C) (Figure 6.50). Gradation A denotes a gravelly
sand, characterized by 1 ess than 40 percent fines and a
significant fraction exceeding 3/4 inch; B is a silty sand
without the generally coarser fraction; and C is a silt
6-53
unit which is generally less than 1 inch in maximum parti-
cle size and contains in excess of 40 percent fines.
The Liquid Limit of the material ranges from 17 to 34 per-
cent with an average of 23 percent. Approximately one
third of the samples were non plastic. Natural moisture
contents ranged from 6 to 23 percent with an average of 13
percent. (One sample gave a moisture content of 53 percent
but was not considered representative.)
The Modified Proctor Test, conducted on 3/4-inch minus
material, gave a maximum dry density of 141 pcf at 6.9 per-
cent moisture. The Standard Proctor Test, at 10.8 percent
moisture on the minus No.4 material, gave a maximum dry
density of 128 pcf.
Permeability tests on samples compacted to Modified and
Standard Proctor values at 2 percent above optimum moistur6
content gave permeabilities on the order of 10-
cm/sec.
Modified and Standard Proctor compaction at 2 percent above
optimum moisture content gave a coefficient of consolida-
tion (Cc) of .06 and .09, respectively. The specific
gravity of the material is 2.72, which is normal for a
glacial till. The undrained shear strength tests run on
samples at 95 percent of Modified Proctor density and 2
percent above optimum moisture gave a friction angle of 37
degrees with cohesion of 648 psf.
Pin-hole dispersion tests showed the material was not dis-
persive.
In conclusion, Borrow Site H material is considered suit-
able for use as impervious and semipervious fill. However,
problems such as wet swampy conditions, permafrost, and the
lengthy haul distance to the site may affect the potential
use of this site as a borrow source.
(h) Borrow Sites I and J
{i) Proposed Use
Reconnaissance mapping was performed within a 10-mile radi-
us of the damsite to locate potential sources of free-
draining gravels for use in the dam shell. The large vol-
ume needs of this material requires that the source be rel-
atively close to the damsite and in an area that would min-
imize environmental impacts during borrowing operations.
As a result, the Susitna River valley alluvium was deline-
ated as a potential borrow source.
6-54
F""':',
~I
)OOo
I
I
-
-
·~
I
I
I
1"""
I
-!
( i i) Location and Geology
Seismic refraction survey performed across the river chan-
nel during 1980-81 indicated large quantities of sands and
gravel within the river and floodplain deposits both up-
stream and downstream from the damsite.
Borrow Site I extends from the western 1 i mits of Borrow
Site E downstream for a distance of approximately 9 miles,
encompassing a wide zone of terrace and floodplain deposits
(Figures 6.51 and 6.53).
Borrow Site J extends upstream from the damsite for a dis-
tance of approximately 7. 6 miles. The site area extends
from river bank to river bank and includes several terraces
and stream deltas (Figures 6.52 and 6.53).
Borrow Sites I and J are fully within the confines of the
Devil Canyon and Watana reservoirs, respectively.
Both sites are in an active fluvial environment. Borrow
Site J is flanked by bedrock, talus and till-covered valley
walls; while Borrow Site I includes extensive terraces ex-
tending several hundred feet up the valley walls above
river level.
(iii) Reserves
For purposes of volume calculation, it was assumed that all
materials with seismic velocity of 6,500 feet per second
represented suitable grave 1 deposits (Table 6.1). Materi-
als with velocities higher than 6,500 were assumed to be
either too bouldery or dense. Not included in the estimate
were:
The river material between the two sites;.
-Materia 1 between the west boundary of Site J and the
downstream area of the damsite; and
-The section from the damsite to Borrow Site E.
This last area was considered to require excessive dredging
and could likely affect the hydraulics of the tailwater.
An active slope failure was identified near Borrow Site H
(Appendix K). If further studies show that the excavation
of river material beneath this slide may result in slope
failure, than this section of alluvium will be left in
place. In summary, a total of 125 mcy of material were
estimated in Borrow Site I extending a distance of 8.5
miles downstream and 75 mcy ·in Borrow Site J over a dis-
tance of 7 miles upstream.
6-55
(iv) Engineerin9 Properties
Individual gradation curves from a total of 45 samples
taken from 22 test pits are presented in Appendix F and
summarized on a composite curve shown on Figure 6.54.
Soil properties determined from laboratory testing are
shown in Table 6.12.
Three basic gradations are present within the two sites.
These are fine grained silty sand, sand and gravel (Figure
6.55). The fine silty sand fraction was encountered in 25
percent of the test pits and ranged in thickness from 6
inches to 6 feet. The second gradation is a sand which
varies from a well-sorted clean sand to a gravelly poorly
sorted sand. This type of material was encountered in only
15 percent of the pits, and where present, underlies the
silt layer with an average thickness of about 4 feet. The
bulk of the samples are of a moderately sorted gravel mixed
with from 20 to 40 percent of sand and silt with less than
5 percent silt and clay size fraction. No indication of
plasticity in the fines was noted.
(i) Quarry Site L
(i) Proposed Use
Quarry Site L was identified during the 1980-81 program as
a source for cofferdam shell material.
(ii) Location and Geology
Quarry Site L is 1 ocated 400 feet upstream from the pro-
posed upstream cofferdam {Figure 6. 56) on the south bank.
The site is a rock knob immediately adjacent to the river
which is separated from the main valley walls by a topo-
graphically low swale that has been mapped as a relict
channe 1 (Appendix J).
The rock in the quarry area is diorite along the western
portion of the knob with andesitic sills or dikes found
farther upstream. The rock exposure facing the river is
sound with very few shears or fractures. The vegetation is
heavy brush with ta 11 deciduous trees on the knob and
aldens with brush in the swale to the south. Little sur-
face water is present on the knob; however, the low lying
swale is marshy. Permafrost may be expected to be present
throughout the rock mass.
6-56
-'
-'i
r-
i
r-
r
'
-i
!
-i
-
-f
,..
i
r
i
-
( i i i )
Quarry Site L 1 i es opposite "The Fins" feature which is ex-
posed on the north abutment (Section 6.l[c]); however,
extensive mapping in this area shows no apparent shearing
or fracture that could be correlative with the extension of
this feature.
Reserves
Because of 1 imited bedrock control, the site has been de-
lineated into two zones for estimating reserves (Figure
6.56). Zone I delimits the total potential reserves based
on assumed overburden and rock volumes, while Zone II iden-
tifies that volume of rock that, with a high degree of con-
fidence, is known to be present (Figure 6.56). Based on
field mapping and airphoto interpretation, the total use-
able volume of material has been estimated to be 1.3 mcy
for Zone I and 1. 2 mcy for Zone I I, over an area of 20
acres.
(iv) Engineering Properties
No testing was performed on rock samples for Quarry Site L.
However, based on field mapping, it appears that the rock
properties and quantities will be similar to those at the
damsite (Section 6.l[d] and [e]).
6-57
-
r
-
ELOCITY
0-1500
1500-3900
3900-4900
4600-4800
4900-5500
5500-7000
7000-10000
10000-15000
15000-20000
20000+
TABLE 6.1: WATANA SEISMIC VELOCITY CORRELATIONS
INFERRE MATERIAL
Shallow, loose dry sands, gravels, soil
Moist Gravels, sands, talus, slope wash, generally well drained. Can include
loose, drained tills and outwash, unfrozen clays.
Moist alluvial terraces, gravels -occurs predominately as surface terraces or as
shallow depth channel fill in relict channel bedrock lows above elevation 2200 -
possible beaded stream deposits.
Water
Granular alluvium, saturated, and possible outwash; may be frozen. May represent
less bouldery beds of stream alluvium and outwash.
Low velocity saturated gravels, outwash. Also higher velocity active river
alluvium and talus velocities. Probably includes majority of frozen alluvium and
tills.
Dense tills, alluvium, boulders, and coarse outwash materials. May include
frozen clays and gravels. Also highly weathered sheared rock.
Sheared and severely fractured and altered bedrock. Over consolidated tills
and/or sedimentary rocks and frozen talus.
Bedrock, velocity represents lower range, fractured and altered rock, while
higher velocities are sound rock.
Sound crystalline bedrock.
TABLE 6.2: WATANA JOINT CHARACTERISTICS*
Jo1nt S1te S t r i k e Ei 1 E S E a c 1 n g** s u r f a c e c o n a 1 t 1 o n s
Set Quadrant (Range) (~vg. J (Range J (~vg. J (Range J (Avg.) · Texture Coating Remarks
All 290°-330° 320° 75°NE-B0°SW 90" 1"-15' 2' Carbonate locally Parallel to major
shears, fracture
NE, SE B0°NE 2"-10' 2' Carbonate at WJ-6 zones and alter a-
and WJ-7 tion zones
NW, sw 320° 90° 1"-15' 2' Planar, smooth to Major carbonate at
locally rough, con-WJ-4
tinuous
16 NW, sw 295° 75°NE 1"-15' 2' Minor carbonate at
WJ-9
II All 045°-0B0° 060° 80°SE-BONW 90° 111 -5 I 2' Planar, smooth to Carbonate locally No shears or alter-
rough at ion zones, minor
fracture zone
NE, SE 050° 85°NW 1"-5' 1 • 5' Planar to irregular, Carbonate at WJ-5
smooth to slightly
rough
NW, sw 065° 90° 2"-5' 2' Planar, smooth to Carbonate at one out-
rough crop
III All 340°-030° oo 40°E-65°W 60°E 0.5"-5' 1. 5' Planar to irregular, Carbonate locally Parallel to minor
rough shears and fracture
zones
NE oo5° 60°E 2"-2' 1 ' Curved, rough Weakly developed
SE 350° 65°W 6"-4' 1. 5 I Planar to irregular, Weakly developed
smooth to rough
NW, sw 345° 60°E 0.5"-5' 2' Planar to irregular, Carbonate locally Strongly developed
rough
IV Variable Shallow to moderate
orientations
Strongest Concentrations:
NE oaoo 10°N 2"-3' 1 I
SE 090° 25°5 ) Planar to irregular, Probably stress
310° 40°NE) smooth to rough, relief, near
discontinuous surface
NW 090° 10°5 1 "-3' 2' sw o• 05°E 6"-10' 2'
090° 25°N
*Surface data only
**When set is present
] 1j ~ J '· \ ,, ~ _, 1
' i
®
\ LOCATION
SCALE
0 ;,,,:;·--.JB MILES
MAP
INDEX
BLOCK AREA COVERED SCALE* FIGURE
NO. REFERENCE
CD DAMSITE VICINITY 1"•2500'
RELICT CHANNEL•
FIGURE 5.1 a
TOP OF BEDROCK r=zsoo' FIGURE 6.35
® ~XPLORATION 1"•500'
DAMSITE• OP OF BEDROCK 1"=500'
FIGURE 5.1 b
EOLOGIC MAP IK=500'
FIGURE 6.2
FIGURE 6.3
® QUARRY SITE A 1·=1000' FIGURE 6.37 ,,
\ ®
(
@) QUARRY SITE B 1"•5001
®
FIGURE 6.38
BORROW SITES C AND F 1"=5000' FIGURE 6.39
® BORROW SITE o 1"=1000'
(j)
FIGURE 6.40
BORROW SITE E 1"=1000'
®
FIGURE 6.43
BORROW SITE H l"= 2500' FIGURE 6.48
. ~ ® BORROW SITE I I"= 2500'
@
FIGURE 6.51
BORROW SITE J I"= 2500' FIGURE 6.52
"
!I @ QUARRY SITE L 1"=500' FIGURE 6.56
* REDUCED REPORT FOAM~T
i
\ SCALE
0 ~,,~oo ... .J2 MILES
\
FIGURE 6.1
N 3,225.000
N 5.226,000 _ ../
N 3 ,227,000
REFERENCE:
/
/
I
/
I
I
I
TILL
2100
g
"' " -----...... ,....
/ --..... "' / ....... ___ -
/
/
/-
1
I /}
---
I ....!!.h!:..._
_/
I
/
' ' '
/
I
/
-~
,,.-'-----.... ---//
-----" TALUS, TILe:-.., /
;/ -/ -------'----~ ---------' ------_/ -------
TIL L
--------
briLL
OUT WASH
--...;:
---
. --i' ---
WATANA
.........._q /; TOP OF ROCK
"---/!.___ A ' D SURFICIAL GEOLOGIC MAP
. I ~
--------
/
/
TILL -------
--2000 -~---
LEGEND
LI TH OL OGY :
c=J OVERBURDEN, AREAS OF TA LUS, OUTWASH, T ILL,
TERRACE DEPOS ITS, ALLUVIUM , AS SHOWN
c=J DI ORITE TO QUARTZ DIOR ITE, I NCLUD ES MI NOR
GRANODIOR ITE
C:=J ANDESITE PORPHYRY,INCLUDES MINOR DAC ITE
AND LATITE
CJ DIO RIT E PORPHYRY
CON TACTS :
Ll MIT OF OUTCROP
LITHOLOGIC
CONTOUR LIN ES:
---TOP OF BEDROCK,CONTOUR INTERVAL 100 FEET
50' CONTOUR S DASHED '
---TOP OF BEDRO CK, CONTOUR INTERVAL 20 FEET
TOPOGRAPHY, CO NTOU R I NTERVA L 50 FEET
~--------------------OTHER :
1900 9 SPRI NGS
NOTES
I SURFIC I AL DEPOS ITS MODIF I ED FROM COE ,1 978 .
2 . TOP OF BE DROCK CONTOURS AR E I NF ERRED BASE D ON
GEOLOGIC MAPPING AN D SUBSURFACE EXPLORAT IONS, AN D
ARE SUBJECT TO V ERIFICATION THROUGH FUT URE DETAILED
---..... --------------/ ------
----_....----
SC ALE 0~~~2~00;;;;;4~00FEE T
FIGURE 6 .2
H 3,226,000
_./
/
I _ _...;
./
'1--&
I
/
REFERENCE : BASE MAP FROM COE , 1978 -I" • 200' WATANA TOPOGRAPHY, SHE ET 8 a 13 OF 26,
COORDINATES IN FEET, ALASKA STAT E PL ANE (ZONE 4 l
I. OUTCROPS SHOWN ON FIGURE 6.2 .
MAP
LITHOLOGY:
r--1 DIORITE TO QUARTZ DIORITE, INCL UDES
l___l MINOR GRANODIORIT E
OTHER :
JOINTS: INCLINED, OPEN I NCLINED ,
VERTICAL ( SE TS I AND II ONLY,
EXCEPT FOR OPEN JOI NTS )
ALTERATION ZON E , WIDTH AS SHOWN
F IGURE 6 .3
E w
IL
z
0
~ w
.J w
2500
2000
1500
1000
'~'• ROO
100 50 0
'-----..!.__j EL .
-2177
1 ;~rr~, /
C) I
/ ;; I ~ /;
/1 crZACCESS I I T UN NELS
/'I-TREND 305°
/ / .-:'>'-'*-=~--=....._,.-.<.4 /
343.-AZIMUTH ---..163•
OF SECTI ON
LOOKING UPSTREAM
~:,, ~ EL. 19
--
• ~ os ---=::-2014 ~
'ill ~ 00% ::· " ~
._ D~' --1894
!CO 50 0
L.....L.......J EL.
DH ·IO -
1830 I;-,_, • % ROD
-1760 1-712 ~ ~QQ 0 ~\.
DH -8 ~ _,,~
,a:>~
-1566 .,..\f>''
~"'"'" TUNNELS
WATANA
GEOLOGIC SECTION W-1
SHEET I OF 2
DH-6
Q .... -1
'1. RQO
~0 EL . ....--1373
-::;;:::;:::::1 _1327
DH ·4
SUS ITNA
RIVER
'<~ji';jil
I
BOTTOM
PROJECTED
330'E
I
2500
2000
1500
1000
LEGEND
LITHOLOGY:
~ ~
D
~ ~
OVERBURDEN , UNDIFFERENTIATED
DIORITE TO OUARTZ DIORITE, INCLUDES
MINOR GRANODIOR ITE
ANDESITE PORPHYRY, INCLUDES MINOR
DACITE 8 LATITE
DIORITE PORPHYRY
CON TACTS :
APPROXIMATE TOP OF ROCK
---LITHOLOGIC , DASHED WHERE INFERRED
STRUCTURE :
r-·1 SHEAR, WIDTH SHOWN WHERE GREATER
i....._.__i THAN 10 FEET
!0\'---; FRACTURE ZONE, WIDTH SHOWN WHERE c;:;,,__J GREATER THAN 10 FEET
D ALTERATION ZONE. WIDTH AS SHOWN
GEOPHYSIC AL SURV EYS :
6 SW·I INTERSECTION WITH SE ISM IC REFRACTlON I LINE
DM ·C 1975, DAMES 8 MOORE
SW· I 1978, SHANNON 8 WILSON
SL 80·2 1980, WOODWARD-CLYDE CONSULTANTS
SL 81·21 1981 , WOODWARD · CLYD E CONSULTANTS
SE ISMIC VELOCITY CHANGE
12F~~O SEISMIC VELOC ITY IN FEET PER SECOND
BOREHOLES :
DR·I9
DH·I
BH ·I
NOTES
CO E ROTARY 8 DIAMOND CORE BORINGS
AAI DIAM OND CORE BORING
INTERSECTION WITH GEOLOG IC
SECTIO N w·s
GEOLOGIC FEATURE DESCRIBED IN
SECTION 6 .1.
SECTION LOCATION SHOWN ON FIGUR E 6.3 .
2. VERTICAL 8 HORI ZONTAL SCALES EOUAL .
3 . SURFAC E PROF IL E FROM I " • 200'
TOPOGRAPHY, COE, 1978.
4. EXPLORATION LOGS AND SEISMIC LINE SECTIONS
SHOWN IN APPENDICIES B,D,H AND I .
5 . EXTENT OF SHEARS, FRACTURE ZONES, AND
ALTE RATION ZONES ARE INFERRED BASED ON
GEOLOGIC MAPPING AND SUBSURFACE
EXPLORATIONS,AND ARE SUBJECT TO
VERIFICATION THROUGH FUTURE DETAI LED
INVESTIGATIONS .
SCALE 0~~~~10~0~--~200FEET
FIGURE 6 .4
;:
w w ...
z
Q
~ w
..J w
2500
2000
1500
1000
"• RQO 100 W •O
L___L__j EL.
~ 1394
•-1277
OH-5
BOTTOM
PROJECTED
155 'W
343 • ._ AZ IM UTH ____..16 3•
OF SECT ION
L OOKING UPSTRE AM
(;)<:) 0 ~""e-" ~/,~ .{f>~ 'b.,~
-r~/'
-;,;1-"> BH-12 ~ PRgJECTED BH-8
140 E PROJECTED
170'E
OH-12
IOo 'Y. Roo
~0
-1328
EL .
-1968
,..Roo
100 50 0
L___L__J EL.
~-2o55
=---1922
DH -24
OH-24
BOTTOM
PRO JECTED
685'E
WATANA
GEOLOGIC SECTION W-1
SHEET 20F2
2500
2000
1500
1000
LEGEND
LITHOLOGY :
OVERBURDEN, UNDIFFERENTIATED
DIORITE TO QUARTZ DIORITE, INCLUDES
MINOR GRANODIORITE
ANDESITE PORPHYRY, INCLUDES MINOR
DACI TE a LATITE
DIORITE PORPHYRY
CONTACTS:
APPR OXIMATE TOP OF ROCK
---LITHOLOGIC, DASHED WHERE INFERRED
ST RUCTURE :
r-•-, SHEAR, WIDTH SHOWN WHERE GREATER
i.._._j THAN 10 FEET
r-·'! FRACTURE ZONE , WIDTH SHOWN WHERE L .. --i GREATER THAN 10 FEET D ALTERATION ZONE, WIDTH AS SHOWN
GEOPHYSICAL SURVEYS :
6 SW-I INTERSECTION WITH SEISMIC REFRACTlON I LIN E
OM ·c 1975, DAMES a MOORE
SW·I 1978, SHANNON a WILSON
SL 80·2 1980, WOODWARD-CLYDE CONSULTANTS
SL 81 ·21 1981 , WOODWARD· CLYDE CONSULTANTS
SEISMIC VELOCITY CHANGE
~~~~0 SEISMIC VELOCITY IN FEET PER SECOND
BOREHOLES : BH·I
. F • FRACTURE
ZONE
LITHOLOGY
DR -19
DH ·I
BH·I
OTHER•
W·5 J,
@
NOTES
S• SHEAR
A• ALTERATION
ZONE
COE ROTARY a DIAMOND CORE BORINGS
AAI DIAMOND CORE BORING
INTE RSECTION WITH GEOLOGIC
SECTION w ·5
GEOLOGI C FEATURE DESCRI BED IN
SECTION 6.1.
SECTION LOCATION SHOWN ON FIGURE 6 .3.
2. VERTICAL a HORIZONTAL SCALES EQUAL.
3. SURFACE PROFILE FROM I" • 200'
TOPOGRAPHY, CO E, 1978 .
4 . EXPLORATION LOGS AND SEISM I C LINE SECTIONS
SHOWN IN APPENDICIES B,O,H AND I .
5. EXTENT OF SHEARS, FRACTURE ZONES, A ND
ALTERATION ZONES ARE INFERRED BASED ON
GEOLOGIC MAPPING AND SUBSURFACE
EX PLORATIONS,AND ARE SUBJECT TO
VERIFICATION THROUGH FUTURE DETAILED
INVESTIGATIONS.
SCALE O~~~~~O~O:.Oiiiiiiii~200 FEET
FIGURE 6 .4 m ~-------------------------------------------------------------------------------------------------------------------------------------------------------
l
TABLE 6.3: WATANA RQD SUMMARY
Borehole DH-1* DH-4• DH-5• DH-6* DH-7* DH-8* DH-9* DH-10 DH-11' DH-12• DH-21 DH-23 DH-24 DH-28 BH-1 BH-2 I BH-3 BH-4 BH-6 BH-8 BH-12 Total Roc k
Ground Surface El. (feet) 1459 1462 1462 1716 1716 1910 1913 2033 2034 1951 1480 1952 2061 1971 2050 1835 2150 2185 1605 1976 1966 Drilled -
Top Of Rock El. (feet) 1415 1384 1402 1713 1708 1894 1909 2020 2018 1942 1407 1947 2054 1958 2032 1826 2123 2174 1598 1964 1949 Average
Borehole Dip** v v v v 59° v 45" v 45" v 60° 45° v v 70° 38° 55" 59" 60" 60° 40° RQD
Vertical
Depth (ft) RQD
Rock Drilled ]
0'-50' (ft) 51,4 45.2 47.9 48.9 49.1 54.5 67.0 48.6 70.3 51.6 59.7 70.5 50.9 29.5 52.5 61.2! 59.1 56.9 58.5 59.2 81.5 1174.0
RQD% 28% 66% 46% 50% 48% 59% 59% 21% 71% 60% 85% 45% 70% 36% 79% 55% I 75% 44% 50% 43% 57% 56%
I
50' -150' " 27.6 69.2 97.2 64.6 79.3 139.5 100.5 144.1 99.9 110.0 41.7 82.1 62.4 104.8 119.81 124.9 115.7 118.4 116.2 151.7 1969.6 l
J
45~6 83~ 51% 60% 67% 62% 68% 77% 53% 85% 49% 70% 10% 76% 23% 96% 54% 64% 75% 72% 65%
I
'
J
150'-250' " 72.1 34.8 65.0 105.1 121.7 109.6 124.4 120.0 120.8 115.8 114.5 154.0 1257.8
44~~ 89% 85% 77% 83% 86% 54% 99% 94% 86% 82% 68% 79%
250'-350' " 33.9 118. 3 14. 3 85.61 119.9 114.9 115.3 114.6 156.1 872.9
85% 82% 73% 75% 87% 99% 81% 79% 62% 80%
'·
350'-450' " 109.5 119.5 115. 1 114.4 114. 3 159.3 732.1
' 91% 46% 99~6 82 84% 79% 79~0
450'-550' " .t•
' 120.6 120.0 115.2 117.8 69.3 542.9
96% 79% 71% 81% 83% 82% J
550'-650' " 125.0 115.1 94.8 102.0 436.9
96% 70% 19~6 88% 83%
650'-750' " 120.0 114.7 234. 7
96% 74% 86%
750'-850 " 15.0 64.0 79.0
100% 95% 96%
Total Hole Length (feet) 79.0 45.2 117.1 146.1 113. 7 133.8 278.6 183.9 279.4 290.5 519.2 112.2 133.0 91.9 281.2 391.0 924.0 937.2 732.4 738.6 771.9 7299.9
Average RQD 34% 66% 68~~ 50% 55Y6 64% 57% 60% 78% 67% 84% 4no 70% 18% 80% 49% I 96% 80% 75% 78% 70% 72YO
I
*COE boreholes
**V = vertical
J
J
J
_j
-
-
-'i
TABLE 6.4: WATANA -BOREHOLE ROCK QUALITY DISTRIBUTION
Rock PERCENTAGE ,IJF CORE IN SPECIFIC RQD RP NGES
Drilled
Borehole ( ft) 0-25% Z5-5m.; 50-75% 75-90% 90-95% 95-1 OO~a
DH-1* 79.0 29 56 8 0 7 0
DH-4* 45.2 16 5 17 52 10 0
DH-5* 117.1 6 15 31 23 3 22
DH-6* 146.1 13 30 44 9 0 4
DH-7* 113.7 13 26 29 29 0 3
DH-8* 133.8 6 11 41 32 8 2
DH-9* 278.6 19 18 25 30 7 1
DH-10* 183.9 25 12 14 23 10 16
DH-11* 279.4 3 5 22 38 17 15
DH-12* 290.5 8 17 29 17 12 17
DH-21* 519.2 0 2 25 22 14 37
DH-23* 112.2 36 22 18 8 9 7
DH-24* 133.0 5 14 42 18 9 12
DH-28* 91.9 61 29 10 0 0 0
BH-1 281.2 2 4 22 26 18 28
BH-2 391.0 24 17 30 19 5 5
BH-3 924.0 7 2 5 12 8 66
BH-4 937.2 6 11 13 9 7 54
BH-6 732.4 5 7 22 33 15 18
BH-8 738.6 3 6 22 30 11 28
BH-12 771.9 6 17 30 19 10 18
Total
Rock
Drilled 7299.9
*COE core was relogged from boxes.
~-:
TABLE 6.5: WATANA ROCK TEST SUMMARY
DIORITE, QUARTZ-DIORITE 1 GRANODIORITE
Compressive Unit Tensile
Borehole Strength Weight Strength
Borehole* Sample Depth (ft) (psi) (pcf) (psi) Other**
BH-1 W-1-41.6 41.6 23,587 167.2
W-1-44.2 44.2 23,587 167.7
W-1-83.9 83.9 169.2 2,019
W-1-134.9 134.9 24,400 168.9 ~-q;--:~
W-1-230.3 230.3 ED 10.8 X 106 psi, v = 0.29
BH-2 10-80 313.8 17,487 169.6
pr-'"
BH-3 W-3-57.9 57.9 10,623 165.6
W-3-199.6 199.6 19,632 169.3 1 '824
EI = 10.6 x 10 6 psi, W-3-320.7 320.7 20,333 169.2 v = 0. 27
W-3-602.2 602.2 4,473 151.0 602 A tered, unit wt. for !;ensile
strength test = 160.5 ,..·_0-.1
W-3-954.8 954.8 11,556 165.9
BH-4 W-4-90.4 90.4 12' 607 165.3
W-4-285.8 285.8 14,233 171.9 ,n-
W-4-533.4 533.4 15,665 170.9
W-4-535.8 535.8 169.1 1,965
EI = 9. 9 X 1 o6 psi, W-4-690.9 690.8 14,414 168.5 1,872 v = 0.24
W-4-888.1 888.1 7,650 168.8 S ightly altered
1'0'•"",
BH-6 80-12 81.65 14,640 166.2
80-14 144.6 21' 147 166.4
80-15 218.1 15' 860 167.3
80-16 233.0 167.2 2,098 s--;
80-19 260.7 15,047 164.8
BH-8 80-28 316.9 16,858 168.3
80-29 322.6 28,020 168.3 2,417
80-31 327.46 26,996 167.3 ~-~·,
80-35 468.4 21' 160 167.1
9,4 X 106 80-38 480.65 23,358 167.0 Eo = psi, v 0.33
BH-12 W-12-328.8 328.8 19,113 165.7 2,450 ,--"-1
W-12-465.4 465.4 18,707 168.6
W-12-657.6 657.6 13' 827 164.3
Average (Acres) 17,500 167. 1 1 '906
~5, 754 so +576 so 1'1{C::-::
DH-8*** 27 44.2 21,450 ET = 11.2 X 1 o6 psi, v = 0.24
28 70.7 29,530 ET = 9.49 X 106 psi, v = 0.20
1 o6 .p,]
OH-10 29 70.2 20,500 ET = 8.60 X psi, v = 0.22
30 176.5 18 '470 ET = 9.41 X 106 psi, v = 0.23
OH-11 31 40.15 10,420 ET = 9.65 X 1 0~ psi, v = 0.27
32 84.3 7,610 ET = 7.13 X 10 psi, v = 0.20
Average (All Tests) 17' 593
~6,080 SD
F'"l
*Locations shown on Figure 5.1
**EB = Dynamic modulus /\'!
***C E testing
ET = Tangent modulus at 50% of failure stress
v = Po is sons Ratio !'"'"'",
SO = Standard deviation
-
f"""· I
!
r
*Locations shown on Figure 5.1
**ET = Tangent modulus at 50~~ of failure stress
v = Po is sons Ratio
SD = Standard deviation
)
Unit
Maximum
Thickness
A&B Surficial 5 feet
Deposits
C Outwash 18 feet
D Alluvium and 15 feet
Fluvial Deposits
E&F Outwash 55 feet
G Till/waterlain 65 feet
Till
H Alluvium 40 feet
I Till 60 feet
J Interglacial 45 feet
J Till 60 feet
K Alluvium 160 feet
j ) ~
TABLE 6.7: QUATERNARY STRATIGRAPHY OF BURIED CHANNEL AREA
Material Ty_[J_e
Organic silts and sands with
cobbles and boulders
Silty sand with gravel and
cobbles
Sand, silt with occasional
gravel
Silt, sand, gravel, cobbles,
partly sorted
Clayey silty sand with gravel
and cobbles, often plastic
Silt, sand and gravel, sorted
Silt, sand, gravel, cobbles
poorly sorted
Sand, gravel, with occasional
silt, sorted
Silt, sand, gravel cobbles,
poorly sorted
Gravel, cobbles, boulders, few
fines
A n 1
, -J
j'
Occurrence
Local
Often removed by post-glacial erosion
Along courses of former drainage
channels in outwash "E"
Generally continuous except in limited
areas
Continuous, thickest nea~ Deadman
Creek
Buried channel and along limited
former drainage channels
Generally cant inuous
Buried channel only
Generally cant inuous
Buried channel only
1 l 1 ]'
Permeability
Moderate
Low to Moderate
Moderate
Low to Moderate
Low
Moderate
Low
High
Low
High
-
-
-'.
-
-
I"""
I
-
-l
-i
Hole/*
Trench
Number
AH-01
AH-02
AH-03
AH-04
AH-05
AH-06
AH-07
Sample Depth
Number From
1 0
2 1.5
3 3.0
4 4.5
5 6.0
6 8.0
7 10.0
8 15.0
3 1 0 5
4 3.0
5 4.5
6 6.5
7 8.5
8 15.0
9 20.0
10 25.0
2 .5
3 1. 5
4 3.0
5 4.5
6 6.5
7 8.5
8 15.0
9 20.0
10 25.0
11 30.0
3 1.5
5 4.5
6 6.0
8 7.5
3 3.0
4 7.5
5 10.0
6 15.0
7 20.0
8 25.0
9 30.0
10 35.0
11 40.0
12 45.0
13 48.0
1 0.0
3 5.0
4 6.5
5 7.5
6 8.0
7 9.5
8 15.0
9 20.0
10 25.0
11 30.0
12 35.0
13 40.0
14 45.0
3 5.0
4 7.0
5 8.5
6 15 .. 0
7 20.0
8 25.0
9 35.0
10 40.0
11 48.0
TABLE 6.8: MATERIAL PROPERTIES -BORROW SITE D
Lab. Mechanical Atterberg
(feet) Classi-Analysis Limits Specific
To ficat ion Gravel Sand Fine L_!:_ _ri Gravity W"' ,.
1 .5
3.0
3.5
4.75
6.75 SM 10 48 42 NV NP 11 0 1
8.75 SM 24 22 54 6.7
10.75 SM 13 51 36 6.6
15.75
2.5 SM 33 38 28 NV NP 25.7
3.75 SM 24 41 35 13.9 NP 11 .4
5.25 SM 23 46 31 NV NP 11 0 2
7.0
9.0
15.75 sc 7 49 44 15.5 2.2 11 0 3
20.75 SM-SC 15 46 39 17.5 4.2 9.4
25.5
.75
2.0
4.0
5.25
7.25
9.5
15.75
20.25
25.25
30.5
3.0
5.0
7.5
8.0
3.75
9.0 SM 0 88 22
11.0 SM 34 47 19
16.5 SM 25 52 23
21.0
25.75
31.5 SM 0 75 25 14 NP 13
36.0 CL-ML 0 55 45 17 14 12
41.25 CL 8 42 50 23 14 12
46.0 SM-SC 11 64 25 39 14 9
48.25
2.0
6.0 SM 10 50 40 15 NP 10
7.5 SM 8
8.0
9.0 SM 0 76 24 13 NP 12
10.0 SM 11
16.0
21.5 SP-SC 0 88 12 17 2 12
26.5 SM 29 38 33 15 NP 9
30.5 8
36.0 SM 10 50 40 17 NP 9
40.6 12
46.0
5.5 11
8.0 I SM 20 50 30 12
9.5 SM 11
16.5 SM 20 53 27 10
20.25 6
25.75 SM 6 71 23 9
35.25 9
40.75 SM 0 80 20 9
48.25
TABLE 6.8 (Cont'd)
Hole/* Lab. Mechanical Atterberg
Trench Sample Depth (feet) Classi-Analysis Limits Specific
Number Number From To fication Gravel Sand Fine LL PI Gravity wo' '0
AH-D8 4 3.5 4.5
5 4.5 6.0 SM 18 65 17 14 NP 15
6 6.0 6.5
7 8.0 9.5
8 9.5 11.0 SM 0 58 42 14 NP 14
9 15.0 16.5 SM 12 71 17 13
10 20.0 20.5
11 25.0 25.5 SP 28 61 11 18 5 10
13 35.0 36.0 ML 10 37 53 13
15 45.0 45.25 9
16 50.0 50.25 9 55 36 7
AH-D9 1 o.o 1. 0
2 1.5 2.5 SM 10 55 35
3 3.0 4.0 SM 10 50 40
4 4.5 6.0 SM 0 60 40
5 6.0 7.5 SM 14 65 21
6 7.5 8.5 SM 0 76 23
7 9.0 10.5 SM 15 63 22
8 15.0 15.5
9 20.0 20.5
10 25.0 25.9
11 30.0 30.5
12 35.0 35.4
13 40.0 41.0 C-ML 0 8 92 21 NP 21
14 45.0 46.5 ML 0 17 83 35 8 25
15 50.0 51.5
16 55.0 55.2
17 60.0 60.25
AH-D1 0 1 o.o 1. 0
2 1. 0 1.5
3 2.0 3.0
4 3.0 3.5
5 4.0 4.5
6 5.0 5.5
7 6.0 7.5
8 7.5 8.5
9 15.0 16.0
10 20.0 20.5
11 25.0 26.0
12 30.0 31.0
13 40.0 40.33 ~.
AH-D11 3 3.0 4.0
4 4.0 6.0
5 6.0 7.5
6 7.5 9.0
7 15.0 16.5
8 20.0 21.5
9 25.0 25.25
10 30.0 31.0
11 25.0 36.5
13 45.0 45.5
15 54.5 54.66
AH-D12 3 1.5 3.0
4 3.0 4.0
5 4.5 5.5
6 6.0 6.5
7 7.5 8.0
8 9.0 9.33
9 15.0 15.3
10 20.0 20.16
11 25.0 25.5
-
-
~
I
L .~
-
r-·
I
-!
I""
I
TABLE 6.8 (Cont'd)
Hole/*
Trench Sample Dell_th (feet)
Number Number From Ia
AH-013 1 0.0 0.5
2 0.5 1. 5
3 3.0 4.0
4 4.5 6.0
5 6.0 7.5
6 7.5 9.0
7 15.0 16.25
8 20.0 20.66
9 25.0 26.5
10 30.0 31,0
11 35.0 35.5
12 38.0 40.0
13 45,0 45,5
AH-014 2 3.0 4.0
3 6.0 7.5
4 7.5 9.0
5 9.0 10.0
6 15.0 16.5
7 20.0 20.5
W-81 0
W,-81 0
*Locations shown on Figure 6.40
Lab. Mechanical Atterberg
Classi-Analysis LiJTits Specific
ficaj:ion Gravel Sand Fine LL Pl Gr;:~vity w•' ,.
SP 0 5 95 59 23
15 40 45 2. 71
-
-
1""'
I
r
Soil Unit
Composite Sample
Coarse
C & D Mean
Fine
Coarse
E & F Mean
Fine
Coarse
G Mean
Fine
Coarse
H Mean
Fine
Coarse
I & J Mean
Fine
PI = Plasticity Index
NP = Non-plastic
TABLE 6.9: GRADATION RESULTS -BORROW AREA D
Coarser than Bet ween No • 4 Finer than Uniried Soil
No. 4 (%) and No. ZOO (%) No. ZOO (%) PI Classification
15 40 45 SM
13 6Z Z5 SM
5 60 35 NP SM
0 49 51 ML
32 50 18 SM
1Z 53 35 NP SM
2 48 50 SM-ML
15 57 28 SM
0 45 55 10 ML
0 18 BZ M...
4 75 Z1 SM
0 73 Z7 NP SM
0 68 3Z SM
Z5 55 zo SM
15 53 3Z 7.5 SM
5 53 4Z SM
TABLE 6.10: MATERIAL PROPERTIES -BORROW SITE E
Hole/* Lab. Mechanical Atterberg
Trench Sample Depth (feet) Classi-Analys·s Li~ its Specific
Number Number From To fication Gravel Sand Fine LL PI Gravity W% -E1 1 2.5 3.0 GP-GM 53 39 B
2 7.0 7.5 GP 74 25 1
E2 1 2.5 3.0 SP 49 49 2
2 5.5 6.0 GW 77 22 1
E3 1 2.5 3.0 GW 7B 21 1
2 10.5 11.0 GP 74 24 2
E4 1 3.0 3.5 GP 82 17 1
2 10.5 11.0 GP 82 17 1
E5 1 1.0 2.0 GW 83 16 1
E6 1 7.5 8.0 SM 25 62 13
ES 1 2.5 3.0 GW 76 23 1
2 6.5 7.0 SP 36 63 1
E9 1 2.5 3.0 -0 10 90
2 4.5 5.0 SM 22 58 20 -3 7.0 8.0 GM ---
E10A 1 3.5 4.0 GP 63 34 3
2 6.5 7.5 SM 0 83 17
E1DB 1 2.0 2.5 GW 64 34 2
E11 1 1. 5 2.0 SM 0 62 38
2 5.0 5.5 GP-GM 61 31 8
E12 1 2.0 2.5 GP-GM 63 31 6
2 2.5 3.5 SM 10 52 38
3 3.5 4.5 SM 29 47 24
E14 1 1. 0 2.0 SP-SM 0 95 5
2 6.0 7.0 SP 69 28 3
E15 1 3.0 3.5 GW 83 16 1
E16 1 3.0 3.5 SP 66 32 2
E17 1 0.5 1. 0 -0 32 68
2 3.5 4.0 SM 0 59 41
3 10.0 10.5 GP-GM 65 30 5
E18 1 0.25 0.75 GP 55 43 2 r 2 2.0 2.5 SM 20 52 28
3 5.0 5.5 GP 63 36 1
4 10.0 1 D. 5 GP 71 27 2
E19 1 1.0 1. 5 SM 0 66 34
2 2.5 3.0 SM 0 79 21
E20 1 1. 5 2.0 SM-ML 0 47 53
2 3.0 3.5 SP 79 19 2
3 7.5 8.5 SM 19 50 31
4 11.0 11.5 SP-SM 66 28 6
E21 1 2.0 2.5 -0 30 70
2 6.5 7.0 GM 85 11 4
AH-E1 2 0.5 1. 0
3 1. 0 1.5 SM 0 52 48 19.6
4 2.0 2.5 ML 0 40 60 27.3
5 4.0 4.25 r
7 6.5 6.75
10 12.0 12.5
11 15.0 15.25
13 23.5 25.0
AH-E2 2 1.5 2.25
3 3.0 3.5
4 5.0 5.75
5 6.5 7.0
6 8.5 9.0
AH-E3 2 0.5 1. 0
3 1.0 1.5 ,-4 1. 5 2.25
5 3.0 3.75
6 4.5 5.5 SP-SM 38 56 6 4.4
7 6.5 7.5 GW 60 36 4 0.7
8 8.5 9.0
9 15.0 15.5
10 16.5 17 .o I I
TABLE 6.10 (Cont'd)
HoTel* Lao. Mechan1ca1 Atteroerg
Trench Sample Depth (feet) Classi-Analys·s Lin its Specific
Number Number From To fication l:iravel ~and t 1ne ~ _t'!_ Gravity W%
AH-E4 2 0.5 1. 5
3 1.5 3.0
4 3.0 4.0
5 4.0 4.5
6 5.0 6.5 SM 2 76 22 17.6
7 6.5 7.25
8 a.o a. 75
AH-E5 2 1. 0 1. 5
3 1.5 2.0
4 2.0 2.5
6 4.0 5.25
8 6.0 6.75
10 7.5 8.5
11 9.0 10.25
AH-E6 2 0.5 1. 5
3 1. 5 3.0
6 6.0 7.0
7 7.5 8.0
8 9.5 9.75
10 20.0 20.75
AH-E7 1 0.0 0.5
3 2.0 3.0 GP 61 37 2 2.3
4 3.0 4.0
AH-EB 2 0.5 1 .5
3 1. 5 2.0
4 3.0 3. 75
AH-E9 1 0.0 1. 0
2 1. 5 2.5 SM 0 71 29 15.7
3 3.0 3.5
5 5.0 5.25
6 6.5 8.0 GM 43 40 17 4.4
*Location shown on Figure 6.43.
-
-
,.... .•
r
i
r
I
-\
r
-I
\
ffole/*
Trench
Number
AH-H1
AH-H2
AH-H3
AH-H4
AH-H5
AH-H6
Sample Depth
Number From
1 0.0
2 1. 5
3 3.0
4 4.5
5 6.0
6 7.5
7 9.0
8 15.0
9 20.0
10 25.0
1 o.o
2 1.5
3 3.0
4 4.5
5 6.0
6 7.5
7 9.0
8 15.0
9 20.0
10 25.0
11 30.0
12 35.0
13 40.0
1 o.o
2 1.5
3 3.0
4 4.5
5 6.0
6 7.5
7 9.5
8 15.0
9 20.0
10 25.0
1 o.o
2 1.5
3 3.0
4 4.5
5 6.0
6 7.5
7 15.0
B 20.0
9 25.0
1 o.o
2 1 .5
3 3.0
4 4.5
5 6.0
6 7.5
7 9.0
B 15.0
11 30.0
12 35.0
1 0.0
2 1.5
3 3.0
4 4.5
5 6.0
6 7.5
7 9.0
8 15.0
9 20.0
10 25.0
11 30.0
12 35.0
13 40.0
TABLE 6.11: MATERIAL PROPERTIES-BORROW SITE H
Lao. Mechan~cal Atteroerg
(feet) Classi-Analys·s Lin its Specific
To fication t;rave.l ~ana r ~ne ~ J:'! Gravity W%
1.5 0 75 25 13
3.0 SM 26 49 25 13
4.0 16
6.0 sc 13 66 22 32 17 17
7.5 CL 14 34 52 34 21 16
8.5 CL 18 27 55 25 7 12
1 o. 0 12
15.5 GM 66 22 12 21 NP 9
21.5 9
26.5
1. 5
3.0 15 62 23 -NP 23
4.0 SM 17
5.5 20
7.0 34 31 35 18 NP 7
8.5 . GM 11
10.0 11
16.0 SM 24 23 33 10
20.83 SM 27 41 32 17 NP 9
25.5 6
30.75 18 42 40 18 5 8
35.7 SM-SC 8
40.75 7
1. 5
3.0
4.0 53
5.5 SM-SC 14 44 42 18 5 19
7.0 14
8.5
10.5 SM 7 52 41 -NP 12
16.5 SM 17 53 30 14 NP 9'
20.25
25.25
1.5
3.0
4.5 GC 45 35 20 23 7 16
5.5 13
7.0 SM-SC 25 35 40 20 4 15
8.5 11
16.0 SM 35 38 27 22 NP 11
21.0
25.5
1.5
3.0
4.0
6.0 SM-SC 22 36 42 23 6 16
7.5 SM-SC 0 55 45 22 6 17
8.5 SM-SC 24 33 33 21 4 9
9.5 24 33 33 21 4 10
15.66
30.25
35.5
1. 5
3.0
4.5
6.0
I 7.0
9.0 SM 22 45 33 -NP 13
10.5 12
15.5
20.25
26.5 sc 10 45 45 23 9 11
31.0
35.5 SM-SC 34 47 19 21 6 8
40.5 8
TABLE 6.11 (Cont'd)
Hole/* Lab. Mechanical Atterberg
Trench Sample Depth (feet) Classi-Analys's L.i,rl its Specific
Number Number From To fication Gravel sand tine LL 1'1 Gravity W"' , :-n
AH-H7 1 0.0 1.5
2 1 • 5 3.0
3 3.0 4.5
4 4.5 5.5
5 6.0 7.5 MC-CL 12 36 52 17 4 14
6 7.5 9.0 17
7 9.0 10.5 CL 7 34 59 29 14 16
8 15.0 16.5
9 20.0 21.5 sc 13 ,~--,
10 25.0 25.66 22 51 27 33 19 13
11 25.66 26.5
12 30.0 30.6
AH-H8 1 0.0 1 .5
2 1.5 3.0
3 5.0 6.5
4 6.5 7.5 -NP 14
5 8.0 9.5 sc 18 40 42 25 11 12
6 9.5 11.0 13
7 15.0 16.5 GC 38 26 36 21 7 7
8 20.0 21.0 GC 40 27 33 21 7 6
9 25.0 26.0 6
10 30.0 30.5
11 35.0 35.25
W80-256 H GC-SC 29 33 38 21.7 9.2 10.9
W80-357 H GM-SM 27 37 36 17. 1 2.5 12.3
W81 H 28 34 38 2.72
W81 H 43 27 30 23 6
*Locations shown on Figure 6.48
-
-
f""'' I
-
r
-
-
-i
I"""'
i
r
l
TABLE 6.12: MATERIAL PROPERTIES -BORROW SITES I AND J
Hole/* Lab. Mechanical Atterberg
Trench Sample Depth (feet) Classi-Analys·s Lin its Specific
Number Number ~rom To fication Gravel Sand Fine LL !'_!_ Gravitl_ W"' ,.
TP-R1 1 0.0 1. 0
2 1.5 2.0 GW 69 29 2
3 2.0 3.0
4 3.0 3.5 GW 72 26 2
5 3.5 4.5 GW 71 27 2
TP-R2 1 0.0 1. 0 GW 77 21 2
2 4.5 5.0 GW 79 19 2
TP-R3 1 1. 0 1. 5
2 4.5 5.0 GW 71 28 1
TP-R4 1 1.0 1. 5
2 4.0 4.5 GW 69 30 1
TP-R5 1 0.5 1. 0 GW 64 34 2
2 3.0 3.5 GW 68 31 1
TP-R6 1 1 .0 2.0
2 2.0 3.0 ML-SM 1 52 47
TP-R7 1 0.5 1. 0 GW 68 31 1
2 3.5 4.0 sw 23 76 1
TP-R8 1 0.5 1. 0 GW 72 26 2
TP-R9 1 0.5 1.0 SM 0 75 25
TP-R10 1 1.0 1.5 SM 0 70 30
2 3.5 4.0 SM-SC 36 50 14
T P-R11 1 0.5 1.0 GW 67 31 2
2 3.5 4.0 GW 70 28 2
TP-R12 1 0.5 1. 0 GW 67 30 3
2 4.5 5.0 GW 68 30 2
TP-R13 1 0.5 1.0
2 5.5 6.0 GW 62 36 2
TP-R14 1 0.5 1. 0 GW 64 34 2
2 5.5 6.0 GW 64 35 1
TP-R15 1 1.5 2.0
2 5.5 6.0 SM 0 55 45
TP-R16 1 0.5 1. 0 SM 0 63 37
2 4.5 5.0 GW-GM 59 35 6
TP-R17 1 1. 0 1.5 GW 73 25 2
2 4.0 4.5 GW 59 34 7
TP-R1 B 1 1.0 1 .5
2 4.5 5.0 GW 58 39 3
TP-R19 1 0.5 1.0
2 3.5 4.0 GW 24 73 3
TP-R20 1 0.5 1 .o SM 3 82 15
2 4.5 5.0 GW 62 34 4
TP-R21 1 0.5 1. 0
2 4.0 4.5
TP-R22 1 1.0 1 .5 GW-GM 65 33 13
2 4.5 5.0 GM 82 17 1
*Locations shown on Figures 6.51 and 6.52.
z
0
i= ~ ... -' ...
2500
2000
1500
1000
I· "THE FINS"
AREA OF MAJOR SHEARS fi ALTERATION ZONES
023.___., AZIMUTH ____.203•
OF SECTION
LOOKING UPSTREAM
"v ··!,II ~· ~ 'j ,,\ 't-SEIS MIC VELOCITY CHANGE • AREAS OF ) ~ ,o; • !, , •· AS PROJECTED FROM SW·3,415'E "'-~FRACTUR E ZONES
v \· ':1 I ' ·r~ . TREND 305• ~~ a MINOR SHEARS
l J 't~ t . . ~ :~ ~~ [:1li ll_ .. \ ~~· j ~ I
" l r.. , . t I ~ I ) ·~ ~. l· .).\ . ' ..
l ) !t.-TREND 3 15• ,,11·' ·I I ~ --1 TREND 310•
"\. L , I~ _-. , rTREND 310· ., • •1 ~
v I TREND 310° i+ !I • ~'~"""
WATANA
GEOLOGIC SECTION W-2
SHEET I OF 2
TUNNELS
2500
2000
I
l 1500
I
I
I
I
.~
)j
1000
LEGEND
LITHOLOGY :
H:.:~·.\1 OVERBURDEN. UNDIFFERENTIATED
II DIORITE TO OUARTZ DIORITE, INCLUDES
L___l MINOR GRANODIORITE
1·.: ... ·.:.·1 ANDESITE PORPHYRY, INCLUDES MINOR
DACITE a LA TITE
I("\\ .. "\ I DIORITE PORPHYRY
CONTACTS:
APPROXIMATE TOP OF ROCK
---LITHOLOGIC, DASHED WHERE INFERRED
STRUCTURE:
SHEAR, WIDTH SHOWN WHERE GREATER
THAN 10 FEET
FRACTURE ZONE, WIDTH SHOWN WHERE
GREATER THAN 10 FEET
ALTERATION ZONE, WIDTH AS SHOWN
GEOPHYSICAL SURVEYS :
<!> SW-I INTERSECTION WITH SEISMIC REFRACTION I LINE
DM-C 1975, DAMES a MOORE
SW-I 1978, SHANNON a WILSON
SL 80·2 1980, WOODWARD-CLYDE CONSULTANTS
SL 81 ·21 1981 , WOODWARD-CLYDE CONSULTANTS
SEISMIC V ELOCITY CHANGE
1 ?fp~O SEISMIC VELOCITY IN FEET PER SECOND
BOREHOLES :
LITHOLOGY
BH-1
F•FRACTURE
ZONE
S• SHEAR
A• ALTERATION
ZONE
DR-19
DH·I COE ROTARY a DIAMOND CORE BORINGS
BH-1 AAI DIAMOND CORE BORING
OTHER•
W·5 -J, ~f~b~C~~~ WITH GEOLOGIC
~ GEOLOGIC FEATURE DESCRIBED IN ~ SECTION 6.1.
NOTES
I. SECTION LOCATION SHOWN ON FIGURE 6.3 .
2. VERTICAL a HORIZONTAL SCALES EQUAL .
3. SURFACE PROFILE FROM I " • 200'
TOPOGRAPHY, COE, 1978.
4 . EXPLORATION LOGS AND SEISMIC LINE SECTIONS
SHO WN IN APPENDICIES B,D,H AND I .
5. EXTENT OF SHEARS, FRACTURE ZONES , AND
ALTERATION ZONES ARE INFERRED BASED ON
GEOLOGIC MAPPING AND SUBSURFACE
EXPLORATIONS, AND ARE SUBJECT TO
VERIFICATION THROUGH FUTURE DETAILED
INVESTIGATIONS.
SCALE
FIGURE 6.5
E
"' !!,
z
0 ~
"' -' "'
2.500
2000
1500
1000
i DAM
I CREST EL. 2.2.10
I
I "t. ROD
100 !50 0
l.__1__..j EL .
---1373
~-1327
DH-4
SUSITNA RIVER
% ROD
!00 50 0
L___L__J EL.
j[~
DH-5
AZIMUTH
023 o ...-oF SECTION-203 o
LOOKING UPSTREAM
"!. RQD
100 !50 0
L__l__...l EL.
DH-12.
-1940
-1650
SL 81-21
PROJECTED
295'W
r
WATANA
GEOLOGIC SECTION W-2
SHEET 2 OF 2
o/oRQD
100 50 0
L____.L.._j EL.
..;jl-20 55
~-1922
DH-2.4
SL 8 1-2.1
PROJECTED
160'E
i
2500
2000
1~00
1000
LEGEND
LITHOLOGY :
OVERBURDEN, UNDIFFERENTIATED
DIORITE TO QUARTZ DIORITE, INCLUDES
MINOR GRANODIORITE
ANDESITE PORPHYRY, INCLUDES MINOR
DACITE a LATITE
I(_,\,.., I DIORITE PORPHYRY
CONTAC TS:
APPROX IMATE TOP OF ROCK
---LITHOLOGIC, DASHED WHERE INFERRED
STRUCTURE:
SHEAR, WIDTH SHOWN WHERE GREATER
THAN 10 FEET
FRACTURE ZONE, WIDTH SHOWN WHERE
GREATER THAN 10 FEET
ALTERATION ZONE, WIDTH AS SHOWN
GEOPHYSICA L SURVEYS :
6 SW-I INTERSECTION WITH SEISMIC REFRACTION
I LINE
OM-C 1975, DAMES a MOORE
SW-I 1978, SHANNON a WILSON
SL 80-2 1980, WOODWARD-CLYDE CONSULTANTS
SL 81 -21 1981, WOODWARD-CLYDE CONSULTANTS
SEISMIC VE L OCITY CHANGE
12F~~O SEISMIC VELOCITY IN FEET PER SECOND
BOREHOLES :
BH-1
F• FRACTURE
ZONE
LITHOLOGY
OR-19
OH·I
BH-1
NOTES
S•SHEAR
A• ALTERATION
ZONE
COE ROTARY a DIAMOND CORE BORINGS
AAI DIAMOND CORE BORING
INTERSECTION WITH GEOLOGIC
SECTION W-5
GEOLOGIC FEATURE DESCRIBED IN
SECTION 6.1.
I. SECTION LOCATION SHOWN ON FIGURE 6 .3.
2. VERTICAL a HORIZONTAL SCALES EQUAL .
3 . SURFACE PROFILE FROM I" • 200'
TOPOGRAPHY, CO E, 1978.
4 . EXPLORATION LOGS AND SEISMIC LINE SECTIONS
SHOWN IN APPENDICIES B,D,H AND I.
5. EXTENT OF SHEARS, FRACTURE ZONES, AND
ALTERATION ZONES ARE INFERRED BASED ON
GEOLOGIC MAPPING AND SUBSURFACE
EXPLORATIONS,ANO ARE SUBJECT TO
VERIFICATION THROUGH FUTURE DETAILED
INVESTIGATIONS.
SCALE
O~~~~IO~O:O.iiiiiiiii2.00 FEET
FIGURE 6.5
z
0
f= :;!
w
_J w
PROJECTED ,
445'E 7
6 SERVICE
SPILLWAY
~~
~ 8 TREND 315°
S,A
BH -3
PROJECTED
25'W
!) ! 1 h ~'"' djj 6"""'
.. fTREND 305°
~
028.,.__ AZIMUTH -208•
OF SECTION
LOOKING UPSTREAM
"1. ROO
~EL.
H·IO
~-2014 ---= •
wil -1830
DH -10
WATANA
GEOLOGIC SECTION W-3
SHEET I OF 2
SUSITNA
RIVER
2500
2000
1500
1000
LEGEND
LITHOLOGY :
[SiJ
D
r::-::::l ~
OVERBURDEN , UNDIFFERENTIATE D
DIORITE TO OUARTZ DIORITE, INCLUDES
MINOR GRANODIOR ITE
ANDESITE PORPHYRY, I NC LUDES MINOR
DACITE a LATITE
[QJ DIORITE PORPHYRY
CONTACT S:
A PPROXIMATE TOP OF ROCK
---LITHOLOG IC, DASHE D WHERE INFERRED
STRUCTURE :
[-! SHEAR, WIDTH SHOWN WHERE GREATER
.--l THAN 10 FE ET
r-.. ..,.., FRACTURE ZONE , WIDTH SHOWN WHERE L ._j GREATER THAN 10 FEET
D ALT ERATION ZONE' WIDTH AS SHOWN
GEOPHYSICAL SURVEYS :
.!> SW·I INTERSECTION WITH SEISMIC REFRACTION
I LINE
OM · C 1975, DAMES a M OORE
SW·I 19 78 , SHANNON a WILSON
SL 80·2 1980, WOODWARD-CLYDE CONSULTANTS
SL 81·2 1 198 1 , WOODWARD -CLYDE CONS ULTANT S
SEISMIC VELOCITY CHANGE
~~~~0 SEISMIC V E LOCITY IN FEET PER SECOND
BOREHOLES: BH ·I
F FRACTURE
• ZONE
L I THOLOGY
DR-19
DH-1
BH -1
OTHER '
W-5 ~
NOTES
S• SHEAR
A• ALTERATION
ZONE
CO E ROTARY a DIAMOND CORE BORINGS
AAI DIAMOND CORE BORING
INTERSECTION WITH GEOLOG IC
SECTION w-5
GEOLOGIC FE ATURE DESCRI BED IN
SECTION 6 .1.
SECTION LOCATION SHOWN ON F IGURE 6 .3 .
2 . VERTICAL a HORIZO NTAL SCALES EQUA L .
3. SU RFAC E PROFILE FROM I' • 200'
TOPOGRAP HY, CO E, 197B.
4 . EXPLORATION LOGS AND SEISMIC LINE SECTIONS
SHOWN IN APPEND ICIES B,D,H A ND I.
5. EXTENT OF SHEARS, FRAC TUR E ZON ES , A ND
ALTERATION ZONES ARE INF ERRED BASED ON
GEOLOGIC MAPPING AND SUBSURFACE
EXPLORAT IONS , AND ARE SUBJ ECT TO
VERIFICATION TH ROUG H FUTURE DETA ILED
INVESTIGATIONS.
SCALE 0~~~~~0~0~--~200FEET
FIGURE 6.6
2500
2000
;:
"' "' ...
1500
1000
'Yo ROD
100 ~0 0
L-...1.._....1 EL.
--13 81
111111
-=-1284
DH ·3
IB ,OOO
FPS I
\
,-, RQO
100 ~ 0
l____.l.____j EL.
-1408
.....i-1329
OH·I
POSSIBLE SHEAR
OR FRACTURE
ZONE <DIP INFERRED )
02 • AZIMUTH ~208 •
B ~F SECTION
LOOKING UPSTREAM
SW·I
W·5 i ~ . ~:.:~.~-~'''. ,,,
1-~ ·~·.·.·.¥··.···.~ "·~·,.,"':,•.,•:.~· ..... ~.,'."..-...,•• .. GF 8 . l•"·•~i!;.·~! .. ••~.,)
I ----•~ •' ,,. ....... ,. .............. '"""""" "'"'""''• •"'.a ~
SHEAR, 0 .2 ,GOUGE ' ••• •• .. ~······:·:-;.:AREA OF MAJOR ALTERATION:::(
· TREND 297 -~'ZONES IN DIORITE a SHEAR '.'•".' I a FRACTUR E ZONES IN r
ANDESITE PORPHYRY f
WATANA
GEOLOGIC SECTION W-3
SHEET 2 OF 2
2500
2000
1500
1000
LEGEND
LITHOLOGY:
EI]
D
r:::::1 ~
OVERBURDEN, UNDIFFERENTIATED
DIORITE TO QUARTZ DIORITE , INCLUDES
MINOR GRANODI ORITE
ANDESITE PORPHYRY, IN CLUDES MINOR
DACITE a L ATITE
DIORITE PORPHYRY
CONTAC TS:
APPROXIMAT E TOP OF ROCK
---LITHOLOGIC. DASHED WHERE INFERRED
STRUCTURE :
1 '1 SHEAR, WIOTH SHOWN WHERE GREATER
i_;_ _ _j THAN 10 FEET
["'''~ FRACTURE ZONE, WIDTH SHOWN WHERE
L-.. .......1 GREATER THAN 10 FEET D ALTERATION ZONE. WIDTH AS SHOWN
GEOP HYSICAL SURVEYS :
1' SW·I L~~~RSECTION WITH SEISMIC REFRACTION
DM·C 1975, DAMES a MOORE
SW ·I 1978, SHANNON a WILSON
SL 80·2 1980, WOODWARD-CLYDE CONSULTANTS
SL 81·21 198 1, WOOOWARD· CLYDE CONSULTANTS
SEISMIC VELOCITY CHANGE
12fp~O SEISMIC VELOCI T Y IN FEET PER SECOND
BOREHOLES: 8H·I
• ZONE .
LITHOLOGY t F FRACTURE
DR·I9
DH-1
BH·I
OTHER ,
W-5 _J,
NOTES
S• SHEAR
A• ALTERATION
ZONE
COE ROTARY a DIAMOND CORE BORINGS
AAI DIAMOND CORE BORING
INTERSECTION WITH GEOLOGIC
SECTION w·5
GEOLOGI C FEATURE DESCRIBED IN
SECTION 6 .1.
SECTION LOCATION SHOWN ON FIGURE 6.3.
2. VERTICAL a HORIZONTAL SCALES EQUAL .
3. SURFACE PROFILE FROM I ' • 200'
TOPOGRAPHY , COE, 1978.
4 . EXPLORATION LOGS AND SEISMIC LINE SECTIONS
SHOWN IN APPENDICIES B,D,H AND I .
5 . EXTENT OF SHEARS, FRACTURE ZONES,AND
ALTERATION ZONES ARE IN FERRED BASED ON
GEDIUOGIC MAPPING AND SUBSURFACE
EXPLORATIONS,AND ARE SUBJECT TO
VERIFICATION THROUGH FUTURE DETAILED
INVESTIGATIONS .
SCALE O~~~I!;O;;Oiiiiiiiiiii2~00 FEET
FIGURE 6.6
2000
1000
PROJECTED
ISO'S
086 • .._._., AZIMUTH ----.-266•
OF SECTION
LOOKING SOUTH
UJ z
•:J I~
'
I
I
I
'
I
. SUSITNA RIVER I
(LOOKING DOWNSTREAM) DIVERSION TUNNELS ~6uE.fJ~7J~~~~~~T~N NE L
"'~'~f{~~f0JJ}£jf~!;ii'~-~);"1~j~Nt1jif' j,'W/,/I~~j----::@;::GF=IA:::----_,~:------------------j~~~~f-------------~
--'<"c·.'.:OL~~·.-~ ~m'" ,.,.
SHEAR,
1.5'GOUG E
TREND 325"
WATANA
GEOLOGIC SECTION W-4
SHEET I OF 3
2000
1500
1000
LEGEND
L ITHOLOGY:
ru
D
D . .
OVERBURDEN, UNDIFFERENTIATED
DIORITE TO QUARTZ DIORITE, INCLUDES
MINOR GRANOOIORITE
ANDESITE PORPHYRY, INCLUDES MINOR
DACITE a LATITE
DIORITE PORPHYRY
CONTACTS :
APPROXIMATE TOP OF ROCK
---LITHOLOGIC, DASHED WHERE INFERRED
STR UCTURE :
,-·-, SHEAR, WIDTH SHOWN WHERE GREATER
i_.__i THAN 10 FEET
:"""! FRACTURE ZONE, WIDTH SHOWN WHERE
i,_,,_j GREATER THAN 10 FEET
D ALTERATION ZONE' WIDTH AS SHOWN
GEOPHYSICAL SURVEYS :
6 SW·I INTERSECTION WITH SEISMIC REFRACTION
I LINE
DM·C 1975 , DAMES a MOORE
SW · I 1978, SHANNON a WILSON
SL 80·2 1980 , WOODWARD · CLYDE CONSULTANTS
SL 81 ·21 1981, WOOOWARO ·CLYOE CONSULTANTS
SEISMIC VELOCITY CHANGE
~~~~0 SEISMIC VELOCITY IN FEET PER SECOND
SOREHOLES : BH·I
F• FRACTURE
ZONE
LITHOLOGY
OR ·I9
DH ·I
BH·I
OT HER '
W·S _J,
NOTES
S• SHEAR
A• ALTERATION
ZONE
COE ROTARY a DI AMOND CORE BORINGS
AAI DIAMOND CORE BORI NG
INTERSECTION WITH GEOLOGIC
SECTION W·5
GEOLOGIC FEATURE DESCRI BED IN
SECTION 6.1.
I. SECTION LOCATION SHOWN ON FIGURE 6.3.
2 . VERTICAL a HORIZONTAL SCALES EQUAL .
3. SURFACE PROFILE FROM I ' • 200'
TOPOGRAPHY, CO E , 1978.
4. EXPLORATION L OGS AND SEISMIC LINE SECTIONS
SHOWN IN APPENDICIES B,D,H AND I .
5 . EXTENT OF SHEARS, FRACTURE ZONES, AND
ALTERATION ZONES ARE INFERRED BASED ON
GEOLOGIC MAPPING AND SUBSURFACE
EXPLORATIONS,AND ARE SUBJECT TO
VER IFICATION THROUGH FUTURE DETAILED
INVESTIGATIONS.
SCALE
O~~~~I00~--~200FEET
FIGURE 6.7
.... .... ....
LL
2000
z 1 ~00
0
~ > ....
-' ....
1000
'
I
I
I
I
~I
~I
i
I
i
086o...--., AZIMUTH _2660 OF SECTION
LOOKING SOUTH
RIVER FLOW-.
<i_ DAM
I I CREST EL 2210
SW-2C '
PROJECTED I
W-2 35'S
DH-11
SW·2B
PROJECTED
65'S
t
%ROD
100 50 0
L.......l-J El.
-----2014 ___,. •
:.:. -1830
DH-10
1250 FPS
I
I
SW·2
PROJECTED loo's
l i ... --... ~"'..;'"'"'~"-i~,::.:.·i;.::.:~··:t~t::.::.i.·;;"l'~· . .:. ::::.:.: ~~,_-~ ----"'..: __ _, __ ,L._-··~~.:.·<:;;;;~:.;..:_.!.:_l ~'·f·-y~:...-·:....---
13,000 FPS L~>l @
A;f/-@ d 3()5• ,~W ~TUNNEL A DIVERSION
TUNNELS ;Yr POWERHOUSE, TRANSFORMER GALLERY, i a SURGE CHAMBER PROJECTED 830' S
I 71 // k \ '1 !
13,500 FPS /· ,f Woj~~TED li 180'S .I 16,200-18,000 FPS
~··:
·II--TREND
f ...J_ AREAS OF
1:\ : FRACTURE ZONES
I a MINOR SHEARS
TREND 310• I\ ;-12,500FPS !!
I I ~I
,, ACCESS
I N ./I ·' ,' ! (
I [._INTERSECTION WITH
v I · { ./
NORTH DIVERSION TUNNEL
WATANA
GEOLOGIC SECTION W-4
SHEET 2 OF 3
2000
1500
1000
LEGEND
LITHOLOGY:
I\J :?;:q OVERBURDEN, UNDIFFERENTIATED
r-f DIORITE TO QUARTZ DIORITE, INCLUDES
L__j MINOR GRANOOIORITE
r:::::J A NDESITE PORPHYRY, INC LUDES MINOR
~ DACITE a LATITE
[Q] DIORITE PORPHYRY
CON TACTS :
APPROXIMATE TOP OF ROCK
---LITHOLOGIC, DASHED WHERE INFERRED
STRUCTURE :
,-·-,
i... . .......i
~'§j
D
SHEAR, WIDTH SHOWN WHERE GREATER
THAN 10 FEET
FRACTURE ZONE, WIDTH SHOWN WHERE
GREATER TH AN 10 FEET
ALTERATION ZONE, WIDTH AS SHOWN
GEOPHYSICAL SURVEYS :
<!> SW·I INTERSECTION WITH SEISMIC REFRACTION
I LINE
OM· C 1975, DAMES a MOORE
SW· I 1978, SHANNON a WILSON
SL 80·2 1980, WOODWARO·CLYOE CONSULTANTS
SL 81 ·21 1981 , WOODWARD · CLYDE CONSULTANTS
SEISMIC VELOCITY CHANGE
~~~0 SEISMIC VELOCITY IN FEET PER SECOND
BOREHOLES: BH-1
F •FRACTURE
ZONE
LITHOLOGY
DR·I9
DH ·I
BH -1
OTHER :
W·5 ,J.
@
NOTES
S•SHEAR
A• ALTERATION
ZONE
COE ROTARY a DIAMOND CORE BORINGS
AAI DIAMOND CORE BORING
INTERSECTION WITH GEOLOGIC
S ECTION w-5
GEOLOGI C FEATURE DESCRIBED IN
SECTION 6.1.
SECTION LOCATION SHOWN ON FIGURE 6 .3 .
2. VERTICAL a HORIZONTAL SCALES EQUAL .
3. SURFACE PROFILE FROM 1" • 200'
TOPOGRAPHY, CO E, 1978.
4 . EXPLORATION LOGS AND SEISMIC LI NE SECTIONS
SHOWN IN APPENDICIES B,D,H AND I .
5. EXTENT OF SHEARS, FRACTURE ZONES, AND
ALTERATION ZONES ARE INFERRED BASED ON
GEOUDGIC MAPPING AND SUBSURFACE
EXPLORATIONS,AND ARE SUBJECT TO
VERIFICATION THROUGH FUTURE DETAILED
INVESTIGATIONS.
SCA LE
0~~~~100~-~200 FEET
FIGURE 6 .7
;:: ... ... ...
"' 0
i ...
.J ...
2000
1500
1000
SL 80·2
BH·I I PROJECTED
145'S
SERVICE ~SPILLWAY
PROJECTED
495'N
oes• ...._AZIMUTH ___.266•
OF SECTION
<§)
AREAS OF ALTERATION,
MINOR SHEARS a
FRACTURE ZONES
TREND 310•
LOOKING SOUTH
RIVER FLOW-
I, , I I, , I I, , I I, ·). I S,A
'FINGERBUSTER'
AREA OF MAJOR SHEARS
. F,A
1
/aonoM
·PRgJECTED
. r 50 s
I
TREND -tl
35o• I .
i i
WATANA
GEOLOGIC SECTION W-4
SHEET 3 OF 3
2000
1500
1000
LEGEND
LITHOLOGY :
~
D
r::-::::1 ~
OVERBURDEN, UNDIFFERENTIATED
DIORITE TO QUARTZ DIORITE, INCLUDES
MINOR GRANOOIORITE
ANDESITE PORPHYRY, INCLUDES MINOR
DACI TE a LATITE
DIORITE PORP HYRY
CONTACTS:
APPROXIMATE TOP OF ROCK
---LITHOLOGIC , DASHED WHERE INFERRED
STRUCTURE :
:·'!) SHEAR, WIDTH SHOWN WHERE GREATER
L---1 TH AN 10 FEET
, .. -, FRACTURE ZONE, WIDTH SHOWN WHERE L .__i GREATER THAN 10 FEET D ALTERATION ZONE. WIDTH AS SHOWN
GEOPHYSICAL SURVEYS :
A SW ·I INTERSECTION WITH SEISMIC REFRACTION
I LINE
OM· C 1975, DAMES a MOORE
SW· I 1978, SHANNON a WILSON
SL 80·2 1980 , WOODWARD · CLYDE CONSULTANTS
SL 81·21 1981 , WOODWAR D · CLYDE CONSULTANTS
SEISMIC VELOCITY CHANGE
12fp~O SEISMIC VELOCITY IN FEET PER SECOND
BOREHOLES :
BH·I
F •FRACTURE
ZONE
LITHOLOGY
DR-19
DH·I
BH·I
OTHER :
W·5 -.j,
@
NOTES
S• SHEAR
A• ALTERATION
ZONE
COE ROTARY a DIAMOND CORE BORINGS
AAI DIAMOND CORE BORING
INTERSECTION WITH GEOLOGIC
SECTION W·5
GEOLOGIC FEATURE DESCRIBED IN
SECTION 6.1 .
I. SECTION LOCATION SHOWN ON FIGURE 6 .3 .
2. VERTICAL a HORIZONTAL SCALES EQUAL.
3. SURFACE PROFILE FROM I ' • 200'
TOPOGRAPHY, CO E , 1978.
4 . EXPLORATION LOGS AND SEISM IC LINE SECTIONS
SHOWN IN APPENDICIES B,O,H AND I .
5. EXTENT OF SHEARS, FRACTURE ZONES,ANO
ALTERATION ZONES ARE INFERRED BASED ON
GEOLOGIC MAPPING AND SUBSURFACE
EXPLORATIONS , AND ARE SUBJECT TO
VERIFICATION THROUGH FUTURE DETAILED
INVESTIGATIONS .
SCALE O~~~I§OO;.iiiii;;i2~00 FEET
FIGURE 6.7
2500
2000
E
~
z
0 ~
"' -' "'
1500
LEGEND
LITHOLO GY:
OVERBURDEN, UNDIFFERENTIATED
DIORITE TO QUARTZ DIORITE, INCLUDES
MINOR GRANODIORITE
ANDESITE PORPHYRY, INCLUDES MINOR
DACITE a LATITE
I(...,\ . ..., I DIORITE PORPHYRY
CON TACTS:
APPROXIMATE TOP OF ROCK
---LITHOLOGIC, DASHED WHERE INFERRED
STRUCTURE :
!)""'7;!
L---l
~
D
SHEAR, WIDTH SHOWN WHERE GREATER
THAN 10 FEET
FRACTURE ZONE, WIOTH SHOWN WHERE
GREATER THAN 10 FEET
ALTERATION ZONE, WIDTH AS SHOWN
GEOPHYSICAL SURVEYS :
i' SW·I r:~~RSECTION WITH SEISMIC REFRACTlON
DM ·C 1975, DAMES a MOORE
SW·I 1978, SHANNON a WILSON
SL 80·2 1980, WOODWARO·CLYOE CONSULTANTS
SL 81·21 1981 , WOODWARD· CLYDE CONSULTANTS
SEISMIC VE L OCITY CHANGE
~~~~O SEISMIC VELOCITY IN FEET PER SECOND
BOREHOLES : BH·I
'
F• FRACTURE
ZONE
LITHOLOGY
DR·I9
DH·I
BH·I
OTHER '
W·5 -l-
@
NOTES
S•SHEAR
A• ALTERATION
ZONE
COE ROTARY a DIAMOND CORE BORINGS
AAI DIAMOND CORE BORING
INTERSECTION WITH GEOLOGIC
SECTION W·5
GEOLOGIC FEATURE DESCRIBED IN
SECTION 6.1.
I. SECTION LOCATION SHOWN ON FIGURE 6.3.
2. VERTICAL a HORIZONTAL SCALES EQUAL.
3 . SURFACE PROFILE FROM I'= 200'
TOPOGRAPHY , CO E, 1978.
4 . EXPLORATION LOGS AND SEISMIC LINE SECTIONS
SHOWN IN APPENDICIES B,D,H AND I .
5 . EXTENT OF SHEARS, FRACTURE ZONES, AND
ALTERATION ZONES ARE INFERRED BASED ON
GEOLOG IC MAPPING AND SUBSURFACE
EXPLORATIONS,AND ARE SUBJECT TO
VERIFICATION THROUGH FUTURE DETAILED
INVESTIGATIONS .
16,000 • 20,000 FPS
<:§)
AREAS OF FRACTURE ZONES a MINOR SHEARS
0920 .._._., AZIMUTH--2720 OF SECTION
LOOKING SOUTH
RIVER FLOW-
%ROO
100 50 0
'----'--' EL. --s -1940
l
•-1650
DH-12
WJ
SLB0·20 a
SW·IA
PROJECTED
40'S
1
WATANA
GEOLOGIC SECTION W-5
%ROD
100 ~0 0 EL.
~-1958
DH-2;--1846
SW-1
0~~~'510~0iiiiiiiiiiiiii2~00 FEET SCALE ~
·28
2000
FIGURE 6.8
ANDESITE PORPHYRY OUTCROP
RIVER LEVEL -NORTH BANK
11 FINGERBUSTER" AREA
WATANA
ANDESITE PORPHYRY FLOW STRUCTURE 8 INCLUSIONS
FIGURE 6.9
ANDESITE PORPHYRY
ABOVE DIORITE OUTCROP
APPROX. EL. 1800 FEET -SOUTH BANK
WATANA
FRACTURE ZONE IN ANDESITE PORPHYRY
FIGURE 6.10
HEALED DIORITE BRECCIA
IN ANDESITE/DLORITE
MATRIX
DIORITE .. , ..
FELSIC
[DIKE
·I
...__ __ FELSIC DIKE
RIVER LEVEL-NORTH BANK
"THE FINS" AREA
WATANA
FELSIC DIKE IN DIORITE
HEALED
SHEAR
FIGURE 6 .11
~
N
JOINT STATION
WJ-7
N•JOO
SET
I
s
SE~ ~ SET~ "'@
'@ 6
N
JOINT STATION
WJ-8
N
JOINT STATION
WJ-6
N•IOO
N•IO
w
N
JOINT STATION
WJ-5
N•IOO
w
E
w
s
N
JOINT STATION
WJ-3
N•80
s
N
JOINT STATION
WJ-2
N•60
w
JOINT
I
'
I
I
I WATA~A I
STATI0N
I
s
@
SET J7
N
JOINT STATION
WJ-1
N•86
~
SET
I
···~.
WJ-2~
N
JOINT STATION
WJ-4
N•IOO
PLOTS
...
~
E
·-----···------
wQJ s~
N
JOINT STATION
WJ-9
N•IOO
Q
SCALE O ~ ........ .;;2\i00io.;;;oi4~00 FEET
NOTES
s
'
c
'+
N
~ ~ ~
A oso~ BO'"SE
' 330° so•
c 045'" IO'"NW
0 285° 30'"NE
E o• BO'"W
NOTE• PLOTTING BY PROJECTION OF
PERPENDICULARS TO JOINT PLANES
~~~~~~RC~ ~[0~~~5R0~E~NISPEHQEURALE.
AREA NET. -
JOINT PLOTTING METHOD
... /'
I. CONTOURS ARE PERCENT CONTOURS SHOWN -I 3 507F JIOOINTS PER 1% OF AREA.
o I I I 1 8 ]5%,
2 · N EQUALS NUMBER OF DATA POINTS,
FIGURE 6.12
w
E
N
COMPOSITE JOINT PLOT
SOUTHEASTQUAORANT
N•721
N
COMPOSITE JOINT PLOT
NORTHEAST QUADRANT
N:525
w
w
E
E
SET
I
Cl Q ()
SET
Jl!: m
SET II
I
N
COMPOSITE JOINT PLOT
SOUTHWEST QUADRANT
N•329
COMPOSJTE JOINT PLOT
NORTHWEST QUADRANT
N•600
WATANA
COMPOSITE JOiNT PLOTS
I
w
w
SCALE 0~ ...... 2o;OO:i;;;;;iiii~400 FEET
NOTES
I. CONTOURS ARE PERCENT OF JOINTS PER 1% OF AREA
CONTOURS SHOWN -I, 3, a 5%. •
2. N EQUALS NUMBER OF DATA POINTS.
3. COMPOSITE PLOTS INCORPORATE ALL JOINT DATA FROM
THEIR RESPECTIVE QUADRANTS,
4. J
0
0INT PLOTS FOR JOINT STATIONS (WJ-1 2 3 4 5 67.8 09)
N FIGURE 6.12 • ' • ' ' I'
5. FOR JOINT PLOTTING METHOD SEE FIGURE 6.12
FIGURE 6.13
VIEW LOOKING NORTH ALONG STRIKE
OF SHEAR; DIP 57° WEST
RIVER LEVEL -NORTH BANK
"THE FINS" AREA
WATANA
TYPICAL SHEAR
SHEAR
FIGURE 6.14
CARBONATE
VEIN
UNALTERED DIORITE
SHEARED a ALTERED DIORITE
EAST SIDE OF 55 FT. WIDE SHEAR/ALTERATION ZONE
RIVER LEVEL-NORTH BANK "THE FINS" AREA
WATANA
SHEAR/ALTERATION ZONE
FIGURE 6.15
DIORITE
GF AI
NOTE:
AERLAL VIEW OF "THE FINS"
LOOKING NORTHWEST ALONG STRIKE
GEOLOGIC FEATURES GF AI AND "THE FINS" DISCUSSED IN
SECTION 6.1.
WATANA
"THE FINS"
TSUSENA
CREEK
NORTH -SOUTH
STRUCTURES
DIORITE/ANDESITE
PORPHYRY
SUSITNA RIVER
~
FIGURE 6.16
NOTE:
SUSITNA RIVER
----FLOW
VIEW LOOKING NORTHEAST
NORTH BANK
GEOLOGIC FEATURES GF4 AND GF 5 DESCRIBED
IN SECTION 6.1.
WATANA
GEOLOGIC FEATURES GF 4 AND GF 5
FIGURE 6.17
L&.J>-t-0:: ->-(l):z::
I.&Ja_
Oa: zo <ta..
1.&..1 .....
a:
0
0
ANDESITE PORPHYRY
NOTES•
LOOKING DOWNSTREAM (WEST)
FROM CENTERLINE
I. GEOLOGIC FEATURES GF5, GF 68, GF 78, AND GF 7C
DESCRIBED IN SECTION 6.1.
2 . DASHED LINE IS ANDESITE PORPHYRY a DIORITE
CONTACT.
WATANA
GF 5
GEOLOGIC FEATURES DOWNSTREAM OF CENTERLINE
FIGURE 6.18
1.&..1 .....
a:
0
0
>-a:
>-
:I: a.. a:
0 a..
ILl
t:
U)
ILl
0 z
ct
GF 78
GF 78
NOTES:
BH-2 "FINGER BUSTER"
SHEAR
I. GEOLOGIC FEATURES "FINGERBUSTER': GF 78, AND GF 7C
DESCRIBED IN SECTION 6.1.
2 . ANDESITE PORPHYRY a DIORITE CONTACT ALONG
"FINGER BUSTER" SHEAR.
WATANA
11 FLNGERBUSTER 11 AREA
NORTH BANK
ILl
~
a:
0
0
FIGURE 6.19
NOTE:
GF 7B
"FINGERBUSTER" SHEAR
VIEW LOOKING NORTHWEST
ANDESITE PORPHYRY OUTCROP
RIVER LEVEL -NORTH BANK
GEOLOGIC FEATURES "FINGERBUSTER" AND GF 7B
DESCRIBED IN SECTION 6.1.
WATANA
GEOLOGIC FEATURE GF 78
... I
FIGURE 6.20
T YPICAL COMPRESSION
TEST FAILURE
ALTERED DIORITE-
COMPRESSION TEST
WATANA
ROCK TESTS
Sl't..tTTIN~& L•t• ~ l~.: TG'$ T
INA.TAtiA "'tTl?
&H • W 3 "5 " t...v -3
OEPTH· 19'1. '. :.z.·e .7'
LA6Nc.·S7 ·l:);,.,i•/2...
TYPICAL TENSILE
TEST FAILURE
St4~1TN A IH'olto PRo~r::cT
Sl't.tTT,Ne. TGN Sl'-c-;r:sr
\.vAT A I'fA £17'1:
iH •W'3 5'" \.41-3
DEI'Tiol· ~0:2..2 '-C,c3. Z..'
L.A8 N c .-S 7oo • 041 -14-
ALTERED DIORITE-
TENSILE TEST
FIGURE 6 .21
0.09
(+)
0.06
0.06
(+)
0.03
0.03
21
0 0.03 0.06 0.09
STRAIN(%)
21
0 0.03 0.06 0.09
STRAIN(%)
ROCK TYPE: ANDESITE
FAILURE STRESS: 20,333 psi
ETso = 9.9 x 10 6 psi, v =0.24
Es = 10.3 x 106 psi, u = 0.25
BOREHOLE: BH-2, SAMPLE No.: 2-80
DEPTH = 27.05 FEET'
LJD= 2.55 Y = 166.9 pcf
0.12 0.15 0.18
H
ROCK TYPE• DIORITE
FAILURE STRESS: 20,833 psi
ETso=I0.6XI0 6 psi, u =0.27
Es=IO.I xi06 psi, u=0.26
BOREHOLE: BH-3, SAMPLE No. W-3-320.7
DEPTH= 320.7 FEET
LtD = 2.60 Y = 169.2 pcf
0.12 0.15 0.18 0.21
(-)
0,06
(+)
0.03
o.o6 ,I o.o3
(+)
I
I
I
I
WATANA!
0 0.03
STRAIN(%)
12
9
0.03
STRAIN(%)
STATIC ELASTIC PROPORTIES
FOR ANDESITE AND DIORITE
'
i
0.06 0.09
o.os 0.09
ROCK TYPE: ANDESITE
FAILURE STRESS: 17,283 psi
ETso=1o.5xlo 6 psi, v=0.27
Es = 10.s x to 6 psi, v = 0.21
BOREHOLE: BH-2, SAMPLE No.: 3-80
DEPTH = 45.3 FEET
Lto ~2.58 Y ~ 166.6 pcf
0.12 0.15 0.18
(-)
ROCK TYPE: DIORITE
fAILURE STRESS: 14,414 psi
ETso=9.9XI0 6 psi, vs0.24
Es = 9.9 x 10 6 psi, u =0.24
BOREHOLE: BH-4, SAMPLE No.: W-4-690.8
DEPTH = 690.8 FEET
LtD =2.42 Y = 168.5 pcf
0.12
(-)
LEGEND
0 AXIAL STRAIN
6 VOLUMETRIC STRAIN
[] DIAMETRIC STRAIN
Es SECANT MODULUS
ETso TANGENT MODULUS AT 50% FAILURE STRESS
u POISSONS RATIO
y UNIT WEIGHT
L;o LENGTH/ DIAMETER RATIO
NOTE
S'AMPLE DIAMETER= 1.77"
FIGURE 6.22
~
300
280
260
240
220
80
60
40
20
0 0cfo
0 0 0 0'
00
00
00
000
0 ~o~--~o~~~,c--co~.~loc---o~.~"----o~.~2oo---~o~.2~,--~o.·3o
100
80
60
20
20
SHEAR DISPLACEMENT IN INCHES
ROCK TYPE:
BOREHOLE :
SAMPLE:
SAMPLE AREA
DIORITE
BH-4
W-4-535.8
2.775 SQ. IN.
40 60 80 100 120 140
NORMAL STRESS (PSI)
POLISHED DIORITE ON MORTAR, DRY
•
160
~
0
200
180
160
140
~ 120
~
0
~ 100
~ • • w
~ 80
60
40
20
['] 8
offi----L---L--~----L---~--~
0
100
80
20
0.05 0.10 0.15 0.20 0.25 0.30
SHEAR DISPLACEMENT IN INCHES
ROCK TYPE:
BOREHOLE:
SAMPLE:
DEPTH:
SAMPLE AREA:
20 40
DIORITE
BH-4
W-4-535.6
535.8
2.775 SO. IN.
NORMAL STRESS {PSI)
160
POLISHED DIORITE ON DIORITE, DRY
!
WATANA
I
DIRECT SHEA~ TESTS
I
240
220
200
280
160
140
l'l
~ 120
~
~
0
<t 100
0
~
• • ~ ~ 80
= ~
"
60
40
20
120
100
80
~ 60
~ w • ~
~ 40
w
~
20
0
0
0
0
GtJ0
0.05
0.05 0.10 0.15 0.20 0.25 0.30 0.35
SHEAR DISPLACEMENT IN INCHES
ROCK TYPE: GRANODIORITE
BOREHOLE: BH-8
SAMPLE: 80-36
DEPTH: 474.3
SAMPLE AREA: 1.93 SQ. IN.
20 40 60 80 100 120 140
NORMAL STRESS (PSI)
NATURAL JOINT; ROUGH, PLANAR W/CARBONATE, DRY
160
LEGEND
~p
~. • "' 0
0
8
[']
PEAK FRICTION ANGLE
RESIDUAL FRICTION ANGLE
PEAK VALUES
RESIDUAL VALUES
VERTICAL DISPLACEMENT
NORMAL LOAD= 25 PSI
NORMAL LOAD= 75 PSI
NORMAL LOAD=I50 PSI
C APPARENT COHESION D FRICTION ANGLE ENVELOPE
I. MAXIMUM SHEAR BOX DISPLACEMENT=0.3 INCHES
2. STRAIN RATE : 0.039 IN./ MIN.
FIGURE 6.23
-!
-!
-
P">
.....
I
-
-
,....
-I
-
,.....
-
-'
-
LEGEND
S.D. S.D. N-NUMBER OF TESTS
C/) S.D.-STANDARD DEVIATION
IJJ 6 (.) z z <( w w a:: :::E ~
(.)
4 (.)
0
u.
0
a:: 2
w
a:l
:::E
~ z
10 20 30
UNCONFINED COMPRESSIVE STRENGTH ( ksi)
DIORITE, QUARTZ DIORITE, GRANODIORITE
(A AI)
en 8 w
(.) S.D. S.D. z
<(
0:: z ~ 6 (.) ~ (.) :::E 0
LJ..
0
0:: w
£II 2 ::!:
~ z
10 20 30
UNCONFINED COMPRESSIVE STRENGTH (ksi)
ALL TESTS (AAI 1 COE)
WATANA
UNCONFINED COMPRESSIVE STRENGTH TEST RESULTS
REFERENCE: 79-c-305 FIGURE 6.24 iii
l ... 1 - -) J --l
30 S.D. S.D.
z ROCK N ~
ILl
:::E ANDESITE II
FELSIC DIKE II
DIORITE, QUARTZ DIORITE
VJ GRANODIORITE 281
ILl u 20 TOTAL :303 z
ILl a:
:::l u u
0
LL.. LEGEND
0 S.D.-STANDARD DEVIATION a: N-NUMBER OF TESTS ILl
aJ
:::E 10 :::l z
10 20 30 40 50
COMPRESSIVE STRENGTH ( ksi)
ALL DATA
WATANA
POINT LOAD TEST DATA
FIGURE 6.25
r
I
-
-
-
""""'
-
""""'
""""'
-
-
-
-I
I
r-
1
0
100
200
1-
1&.1
1&.1
LL. 300
:::t:
1-
a..
1&.1
0
1&.1
...J
0 400
:::t:
1&.1 a:
0
III
...J
C(
(.) -500 1-a:
1&.1
>
600
700
BOO
K, COEFFICIENT OF PERMEABILITY (CM/SEC)
~ ----------r--------------------------------
_,~ 0 \ ........ ,
/ ,,
/
,;' \ (
@ 1\ ' --I ' r---AVERAGE PERMEABILITY
"\ (!) I ) I I
( 0 I
' / ", (/
\ G) \
I .... t--... -I 0 -"' I )
/
I _,/"' I
I (!) /
MAXIMUM .. I /
'---MINIMUM
I •
I I
I
G) /
I ' ' I ' ' I ' I ) I
/ ~ ~./·
I I
I I
\ @ \
............. \ \ I --I ... "\ 0 ) I
I I
0 I ( I
BASED ON: BH-I,BH-4,BH-6,BH-8, \ \( BH-12 I DH-1, DH-3,DH-6, \@
DH-8, DH-11 \
\ \ I 0
WATANA ROCK PERMEABILITY
FIGURE 6.26
2124.7
2120
2100
2180
2060
;: w w
~
;20«1
2
~ > w
~
w 2020
2000
1980
1960
1940
TEMPERATURE (•C)
~·r-~::·~4~":~-3~~~·:2~~==·il;:=:=:of=~===l====~=2::~~;~~3~:-~4~----i' ~ STICK UP-4.4 FEET ( 1981) ~-
40
60
" w w
II.. 120
w
~
0
%
z
~
0
0
% ... 160
~ w
0
200
240
DIP-550(11-11-81)
NOTE : SCALE ADJUSTEO ACCORDING
TO FIELD BOOK CHANGES.
260L_------------------------~------------------------_j
1609.8
1601.9
1580
1560
1540
1520
;:
t::JISOO
~
z
0
" ~ 1480 w
~ w
1460
1440
1420
1400
1380
TEMPERATURE (•C) -· -4 I -3 -2 -1 o 1 2 4 ' 0
40
60
;: w
~ 120
w
~
0
%
z
~
0
0
%
~ 160
w
0
200
240
260
I
STICK UP-0..0 FEET ( 1981)
DIP-GO•
SUSPECTED
READING I
ERROR
BH-6
NOTE: DUE TO PROBLEMS ENCOUNTERED IN FIELD MEASUREMENTS, THE FOLLOWING ADJUSTMENTS
WERE PERFORMED TO CONFORM TO EXISTING RELIABLE DATA. THESE FIXED LATERAL
SHIFTS[ MAY NOT CORRECT THE FULL MAGNITUDE OF THE DISCREPANCIES.
ADJUSTMENT SUBTRACTED
DATE OF READING FROM CALCULATED READING {°C)
11-21-sO 14.92
4·26-Bl 13.95
5-24-91 14.63
6·25-81 14.54
a-3-91 14.82
I
WATAN~
THERMISTOR DAfA-DAMSITE
SHEET I 0F 2
!
LEGEND
LITHOLOGY:
~ GROUND SURFACE
~ TOP OF ROCK
BOREHOLES'
AP
OH
OR
AH
6H
AUGER BORING I
DIAMOND CORE BORING CORPS OF ENGINEERS
{19781
ROTARY DRILL HOLE
AUGER HOLE I
ACRES AMERiCAN INCORPORATED
BORE HOLE ( 1980 6 1981)
DATA SOURCES :
0
0
0
X
0
6
@
0
~
0
INDEX OF THERMISTOR READING DATES :
•JULY 30, 1980
NOVEMBER 21, 1980
APRIL 19, 19BI
MAY 24, 1981
JUNE 24, 1981
AUGUST 3,1981
NOVEMBER II, 1981
NOVEMBER 13, 1981
DECEMBER 9, 1981
DECEMBER 15 8 16, 1981
JANUARY 4-7, 1982
CORPS OF ENGINEERS THERMISTOR DATA
POINTS. (CONNECTED BY DASHED LINES)
0 JULY 11, 1978
0 AUGUST 10, 1978
6 AUGUST 23, 1978
OCTOBER 25 8 26, 1978
0 NOVEMBER 29 6 30, 1978
1. LOCATION OF BORINGS SHOWN ON FIGURES 5.1a, !i.lb
AND 6.40.
2. THERMISTOR STRINGS MANUFACTURED BY
INSTRUMENTATION SERVICES IN FAIRBANKS, ALASKA.
3. BORINGS BH-3, BH-6 ARE PERMANENT MULTI-POINT
THERMISTOR STRINGS WITH TWO THERMISTORS AT EACH
READING POINT. DATA FOR TWO POINTS IS AVERAGED.
ALL OTHER BORINGS ARE PVC PIPE, CAPPED AND
FILLED WITH ANTIFREEZE (ETHYLENE GLYCOL) MIXTURE.
READINGS TAKEN WITH A THERMISTOR CABLE FITTED
WITH REDUNDANT (SINGLE PRIOR TO 1981 1 THERMISTOR.
4. THERMISTOR READOUT BOX-KEITHLEY 172 A, USED FOR
1980 THRU 1982 READINGS.
5. TOP OF ROCK ELEVATIONS SHOWN ONLY WHEN
ENCOUNTERED.
6. BORINGS ARE VERTICAL UNLESS A DIP IS SHOWN.
-3 -2 -r o 2 3•c
SCALE
27 28 29 30 31 32 33 34 35 36 37 Of
FIGURE 6.27
TEMPERATURE (°C)
-3 ·2 -I 0 I 2 3 4
1950.9 0 ' ~ 1941.4
STICK UP-
1.8 FEET
1920 (1978)
40 q
" 1900 9
r <) ;: 0 ;: w w w j) w 1880 !0 i5 !0
z ~so <1 0 0 ' ~ % " 1860 z w ~ Q ~ 0 p w 0
% ' ~ <,i 1840 ~ r w ' 0 0 120
1820
1800
160
DH-12
TEMPERATURE (°C)
-3 -2 -I 0 I 2
2061.4 0 ~"'" "' -
2054.5
3 4
~
2040 STICK UP-5~ 1.0 FEET
(1978)
2020 40 ~ l'l.,
0' I)
""' 0 ;: 0:1;jc)
w ""'0 ~ 2000 w
""'I) ~ !0 w ""'0 w ~ !0 0 0"' (l z ; 80 0~~ 0 1980 ~ ~ ""' ';! 0 0 w % ~ w li: 1960 w
0
1940 120
1920
1900 160
DH-24
1480.0
1460
1440
;:
w w
!0 1420
z
0
~1408.7
w
~ 1400 w
1380
1360
2044.9
2040
2020
E 2ooo
w
!0
z
0
" ';! w 1980 ~ w
1960
1940
TEMPERATURE (oC)
•3 -2 -I 0 I 2 3 4
0 ' ' 1951.5
0--
1946.6
~ 1940
STICK UP-
2.0 FEET
;: (1978)
w DIP-57.6° ~ 40
w 1920
~
0 ?-Xi ~
z
~ 0 ;: 0 w 0 w ~ ~ 1900 ~ ~
~ 80 z
0
~ w
~ w
1880
120
1860
NOTE•
FLUID WAS FROZEN IN Pl~i AT 1.5 FEET FOR ATTEMPTED
READING ON DEC.15, 1981. ' 1840 160
I
DH-21
TEMPERATURE (oC)
-3 ·2 -I 0 I 2 3 4
0 ,/' 1971.0
? 1961.8
STICK UP-
4.0 FEET
,/'
{JULY, 1980) 1940 DJP·44°
40
1920 ;:
w f-w ;: !0 w
~ ~ 1900
0
% 80 f-z
z 0
~ ~
0 ~ 1880
~ ~ ~ w ~ w
0
1860
120
1840
1820
160"---------------_i ____________________ ~
DH-25
WATJA
THERMISTOR DATA DAM SITE
SHEET 2
1
0F 2
TEMPERATURE (OC)
·3 -2 -I 0 I 2 4
0
; --~ ~/ STICK UP-C<f 1.0 FEET
([978)
DIP·45° f 40 g
~ ;: w -w
i !0
w
~
0 ~ z 80
~
0
0
!' w 0
120
160
DH-23
TEMPERATURE (°C)
·3 ·2 -I 0 I 2 3 4
0 <),_' --" v gf STICK UP-
I.OFEET ' {1978)
40 <:! q
q
;: & w w g !0
w
~ 0 0
~ 80 ~' z
~ ~ 0
0
~ ,/! li: w ¢ i 0
0 -3 -2 -I 0 2 3"C 0 SCALE 120 8' 32 33 34 35 36 37 ., 27 28 29 30 31
160 L_ ______________ _L ____________________ __j
DH-28
FIGURE 6.27
2339,6
2320
;:: w ~ 2300
z
0
~
~ 2280
" w
2260
2240
2151.4
2140
;:: 2120
w w "' z
Q 2100 ~ 2096.4
> w
" w
2080
2060
2294.7
2280
E 2260
~
z
0
~ 2240
> w
" w
2220
2200
TEMPERATURE (°C)
-I 0 2 3
0
STICK UP-'1 ;:: 2,8 FEET p w (1978) w 0 "' <> ~ 40 <> 0
<> • z
z g: • 0
0
z
~ • w
0
so
DR-14
TEMPERATURE (°C)
-I 0 2 3
0
;:: w w
"' ~ 40
0 z
z • 0
0
z ~ • w
0
so
DR-19
DR-26
NOTE> TWO SETS OF OCT. 26,1978 READINGS
WERE TAKEN ON TWO DIFFERENT
DIAMETER PROSES (DOTS WITH DASHED
LINES).
4
4
2172.0
2160
2140
2120
2100
2080
2060
§
!!: 2040
z
0
~
~ 2020 w
2000
1980
1960
1941.0
1920
1900
-I
0
40
so
;::
l::l120
"'
200
240
28 0
-
0
STICK UP-
3.0 FEET
(1978)
TEMPERATURE (°C)
I 2 3 4
'' '
l· D
~t ~, ~ <f'o ~ !
'
'
I
~-It'
'ol! ~
~
~ '
~ '
~
~~
~-~
~ t
~
'
DR-18
WATANA
THERMISTOR DATA-RELICT CHANNEL
SHEET I OF 2
TEMPERATURE c•cJ
·I 0 I 2 3 4
2229.1 0
2220 <r-~;r
STICK UP-~lAw 2.0 FEET
2200 (1978) ,0¥ ~ 40 <5>r ~ 2180 0 (> I)
:.~ Q if do 2160 * c) 6 <)
so . ' 1 * ¢ 2140 • 0
4 q • 0-,,
2120 ( % '
!'
;:: ¢' 9 ~
E t::l 120 ? 0 "' ~ 2100 w 4' q
" 4 Q
z 0 I) z ~ ;., • 0 z 4 ~ • q
~ 2080 0
I ' 4 9 w 0
" z ,, ~ w ~ iii! 4 f!i 160 4 () 0 '• 2060 4 0
~\ 4 c)
·1,!., 4 0
1'\ ~ 0
2040 ~-i c)
c)
200 ~p. \ c)
Q
2020 ~-~ ' " ' ,, -.: <J>
I o:
2000 t " ' :1 ~ p
240 • !:> 4 >I -: 4 0
1980 ~4 0 ,, 4 0
~ 4 c)
:, 1::. Q
1960 0 0
280
DR-22
-3 -2 -1 o 2 3 •c
SCALE "1---r"-,--,r--r--,_--r-~--,--L~-,~
27 28 29 30 32 33 34 35 36 37 •F
FIGURE 6,28
TEMPERATURE (°C)
-2 -I 0 2 -2
22.21.6 0 2262..9 0
2.200 -20 -20
~ 22.40 ~ w w
w w
;: " ;: !0
w w w
~ 2180 ~ 40 w 5 40 0 ~ 2.220 ~ z ~ z
0 z 0 z
~ ~ ~ ~ 0 0 ~ 0 60 > 0 60 ~ 22.00 ~ 2160 ~ ~
w ~ w ~
~
w w 0 0
so so
2140 2180
STICK UP-3.5 F~ET
( DEC.,I981)
100 100
AH-05
TEMPERATURE C"Cl
-2 -I 0 2 3 -2
2276.1 0 ' ' 2.319.1 0
I ~
22.60 2.300 -20 ~ -20
~ ~ w w w w
E 2240 !0 ;: !0
w ~ 40 t!l 2280 ~ 40
" 0 !0 0
z ~ z ~
2 z 0 z
~ 2220 ~ ~ 2.2.60
~ g 60 g 60 r-w ~ w ~ ~ ~ w ~ w ~ w w
2200 0 0
so 22.40 so
1980 100
f-STICK UP-3.7 FEr
(OEC.,I981)
2.2.20 100
AH-08
TEMPERATURE (OC)
-2 -I 0 2 3 -2
2358.0 0 2337.9 0
~
2340 20 2320
-20 ~ ;: ~ w w w w
§2320
!0 ;: !0
I t!J2300 ~ 40 ~ 40
!0 0 !0 0 ~ z ~ z z 0 z 0
~ 2300
~ ~ 2280
~ 0 g 60 w 0 60 w
~ ~ ~ ~ w ~ w ~ ~ ~ w w 0 2260 0
2280 so so
STICK UP·3.1 FEET
2260 (DEC.,I981) 22.40
lOb 100
AH-011
TEMPERATURE ("Cl
-I 0 2 3
' '
"'----_
7 g
I;
STICK UP-2..6 FEIET
(DEC.,I981)
AH-06
TEMPERATURE (°C)
-I 0 I 2
"'-~<)
STICK UP -4.7 FEr
(OEC.,I9BIJ
AH-09
TEMPERATURE
-I 0 I
\
STICK UP·4.0 FEr
(DEC.,I981)
AH-012
(OC)
:
2 3
•
I
WATANA
2242.9
2220
;: w w
" ~2200
z 0
~ > w
~ 2180
w
2160
2357.8
2340
;:
t!l2320
!0
z
0
~2300
w
~ w
2280
2260
2272.7
2260
;: 2240
w w
!0
z ~ 2220
~ w
~ w
2200
1980
THERMISTOR DATA-RELICT CHANNEL
SHEET 2 OF 2
• I
!
TEMPERATURE ("C)
-2 -I 0 2 3
0
-20
~ w w
!0
~ 40 0
~
z
~ 0
0 60
~
~ ~ w 0
so
STICK UP-1.9 FEET
(DEC,, 1981)
100
AH-07
TEMPERATURE ("C)
-2 -I 0 I 2 3
0
~ ') _ 20 r
~ w ~ w
!0
~ 40 r-~ ,
~ ,
z
~ 0 60 0
~ ~ ~ w 0
so
STICK UP-1.0 FEr
(DEC.,I981)
100
AH-010
TEMPERATURE ("C)
-2 -I 0 2 3
0
~ l _20 ~
~ w ~ w
!0
~40 r-
0
~ ~ z
~
g 60 r-
~ -3 -2 -I 0 2 3 •c
~ ~ w SCALE '-r-_,l'-,--r'-r-+-r--'r--,-'-r---r'
0
so~ 27 2.8 2.9 30 31 32 33 34 35 36 37 "F
-STICK UP-3.5 FEET
100
(OEC.,I981l I
AH-014
FIGURE 6.28
TEMPERATURE (°C) TEMPERATURE (°C) TEMPERATURE {°C) _, -2 -I 0 I 2 ' _, -2 -I 0 I 2 ' 2079.6~
_, -2 -I 0 I 2 ' 2127.5~ 0 ' 1970.9 ~ 0 '
II 2120
~ 1960 ~
20 _ 20 r 2060 20 ~ I E ~ ;::
2100 w
'
w
w ..-1940 w I -w ;:: "' ~ ~ "' ~ ~ ::; w w w w 40 w ~ 40 ~ 2040 40 "' ~ "' 0
' 6 ~ 2080 0 z ~ z ~ ~ r z !:! 1920 z 0 z ~ ~ 60
~ ~ i ~ ~ ~ " c 60 r ! ~ 2020 60 w w ~ ~ ~ ~ ~ -~
w2060 t w t r w ~
1900 ~ w w w c 0
I
0
eo eo f-2000 eo
2040 STICK UP~ 0.0 FEET 1880 f-STICK UP~4.0 FEET I ~ STICK UP~ 4.0 FEET
(DEC.,I981) {JAN., 1982) i 1980 L 100
{JAN.,I982)
100 100
AH·HI AH-H2 AH·H3
TEMPERATURE (°C) TEMPERATURE (°C) _, ·2 -I 0 I 2 ' _, ·2 -I '0 I 2 ' 2188.4 ~ 0
t>--.____
2093.5 ~ 0 ' ~~ ' -,-
2180 ~ 1-20BO
!I I _20 20 1-
~ t ;::
2160 w 1-w w ;:: "' )::" 2060 w
"' w ~ 40 w w 40 r w w "' 0 "' ~
0 ' 5 2140 X z ~ 1-z ~ 2040 z ~ ~ ~ ' 0 ~ 8 60 > c 60 w ~ w X ~ ~
w 2120 ~ w t 1-~ w 2020 w c c
80 eo
' 2100 STICK UP-3.5 FEET STICK UP~ 3.0 FEET
(JAN., 19B2) 2000 (JAN.,19B2) I
100 100
AH-H7 AH 1·H8
BORROW SITE H i
'
' BORROW SITE D I
I
TEMPERATURE (°C) TEMPERATURE (oC) _, -z -I 0 I 2 ' ., -2 -I !o I 2 ' 2245.7 ~ 0 2295.B~ 0 <>----0, --='-·0
2240 ;~-q:r,2 -::-.~
2280
-20 ~ 20
2220 ~ ~ rE w
;:: w ;:: w
w "' t:l 2260 r"' I w 40 1-~ ~ 40 "' r ~ ; 2200 }-0 z
I -~ -: 0 I ~ >•c ~ _,
0 z 0 z ~ ~ ~ 2240 r g I SCALE 1 ~a d9 ' " g 60 60 I ,. 37 °F w w I 27 30 " " " ,. >6
jj 1980 ~ ~ ~ ~ t w 1-
I
w w ~ 0 2220 1-0
80 f-eo
1960 ~ 1-STICK UP-3.2 FEET STICK UP~3.2 FEET
(1978) 2000 L (1978) !
100 100
AP-8 AP-9
WATANA
THERMISTOR DATA -BORROW SITE H • S..BORROW SITED
FIGURE 6.29
WATANA
DAM SITE
GENERAL VIEW OF INLET AREA
a WESTERN HALF OF OUTLET ZONE
SEE
SKETCH
BELOW
/
ARTIST'S SKETCH
WATANA
RELICT CHANNEL PHOTOS
SHORTEST FLOW PATH
APPROXIMATE EMERGENCY
SPILLWAY SITE
LEGEND
CONTACTS'
NOTES
APPROXIMATE NORMAL MAXIMUM OPERATING LEVEL,
EL.2185'.
POSSIBLE FLOW PATH IF SEDIMENTS ARE
PERMEABLE.
RELICT CHANNEL PROFILES SHOWN ON FIGURES 6.31 AND 6 .33
2. PHOTO LOCATIONS a RELICT CHANNEL TOP OF ROCK
SHOWN ON FIGURES 6 . 30 AND 6. 35
3. PHOTOS TAKEN SUMMER I980(LEFT) a SUMMER 1981
(RIGHT).
4. RIGHT PHOTO LOOKS DOWN SHORTEST POTENTIAL FLOW
PATH . CLEARED SPOT NEAR CENTER OF PHOTO IS
TOPOGRAPHIC LOW, EL. 2200 FEET. PHOTO LOCATION
SHOWN ON LEFT PHOTO.
5. ARTISTS SKETCH LOOKS OPPOSITE DIRECTION OF
RIGHT PHOTO.
FIGURE 6.30
• w z
~
o AZIMUTH 224 o 044 ....---0F SECTION-
LOOKING TOWARDS WATANA RESERVOIR
2500 r 5
TO WATANA
EMERGENCY SPILLWAY ..
AND DAM -2500
;: 2300
w w
~
z 2100 0
\i > w
~ w 1900
1700
2500
2300
~ 2100
~ ~ 1900
1700
2700
2500
;: w w
~
z 2300
0
~ w ~ w 2100
1900
~ DR~22 OM-A-i PROJECTED DR~20 jSS
1 -v45'N-W?
1
w-l 7 1. PROJ~CTE~7 /w~J6 _
r !:·····················.. / J, r1,2so FPS ""
215 s~~r( f-~ ._: -~ ~ ~-~ ~·..: ,., .. .,.,_ .. ,, '~-~ ~ :;~ ;~\Q~~~SJ~T.Y.~A_NP. ~(~Q~~Q~.S~ i.~Ltif.LA_L~ i:i~t~~~t{t~ ~. ;_ ~~~~\.i:t"&:..·~~'\-"~\~,:_ Ylitt~:..:~ ~ :,: ~ ~~~ ~ ~: ~ ~:~;..:.: ~=,: :..:: ~:..·.: ~~0· -~~~ -~~~-~ '(GL.t:c1AL • 6iiiWASH }-:.1_ ~·SANOY" S'il.t· AND 'SIL~.;:~ :..:..: ~ .: ~ ;<:: '' .. ~ '-·············· .... '@' Sil.TY'S'AND 'iAi..i.iiViUt.ii..:.:. ~""!":"~."i"l,,,, •••• H •• >'f\ IY... ·l...V·~. 6 ·~~~~ \,[_) ~ SANOY GRAVEL \ALLUVIUM)-.: ~~y (LAKE OEPOSITlJ'V............... -
--------6,500FPS .f.-siLTY BOULDERY SANDITILLl (!) \.8 ,500 •9,
0007
ps, ----..... _ 0 CLAYEY SILTY ·r--r.;..LT'f~YG~~-------0 SANDYGRAVELIALLUVIUMJ__..· -----~N.Q.1JJ.L.!:. • (~L~u.-..16,000FPS
--- ---• ".f.-BOULDERY SILTY SAND(TJLL} 0 --~ DIORITE,SHEAR ZONE-
14,250 FPS ~11§111$1 ~SANDY GRAVE,!,,-.. -:r;" ------12 000 FPS -......{!I~UVIUM) . ~fi!J''tlf-15,000 FPS '
® BOULDERY GRAVEL \ALLuViUMJ..i= . ---_..-
QUARTZ DIORITE_,. 14,500 FPS
L ' 50+00
' 100+00
' 45+00
' 95+00
' 40+00
' 90+00
... SECTION CONTINUES TO STATION 220+00
,. GROUND a BEDROCK SURFACE RISING
' 150+00 ' 145+00 ' 140+00
' ' 35+00 30+00
85+00 80+00
25+00
75+00
' 20+ 00
70+00
o AZIMUTH
OOI ....,__OF SECTION -IBI 0
LOOKING TOWARDS WATANA RESERVOIR
' 135+00 ' 130+00 125+00 ' 120+00
15+00
65+00
' 115+00
WATANA
' 10+00
60+00
' 110+00
5+00
' 55+00
' 105+00
' 0+00
50+00
' -100+00
REFERENCE• DAMES a MOORE, 1975. RELICT CHANNEL SECTION
COE, 1979.
2300
2100
1900
1700
2500
2300
2100
1900
1700
2700
2500
2300
2100
1900
LEGEND
LITHOLOGY'
'Ulr.61l!e!lii! BEDROCK (INFERRED TO BE DIORITE)
OVERBURDEN, STRATIGRAPHIC UNITS
AS SHOWN
CONTACTS'
APPROXIMATE TOP OF ROCK
NORMAL MAXIMUM OPERATiNG LEVEL
EL.2185
BOREHOLES: DR-20
@ STRATIGRAPHY --EB
DR-20 COE ROTARY DRILL BORING
GEOPHYSICAL SURVEYS'
e, OM-A SEISMIC REFRACTION SURVEY END OR TURNING
I POINT-1975, DAMES a MOORE
12,000
FPS
OTHER:
W-16 I
SEISMIC VELOCITY CHANGE
SEISMIC VELOCITY IN FEET PER SECOND
INTERSECTION WITH CROSS SECTION W-16
I. SECTIONS READ FROM TOP TO LOWER LEFT
( STA. 0+00 TO 150+00) SEISMIC LINES OM·A a 8
2. SECTION LOCATION SHOWN ON FIGURE 6.35.
3. SECTIONS W-16 a W-17 SHOWN ON FIGURE 6.35.
4. VERTICAL AND HORIZONTAL SCALE EQUAL.
5. SECTION ELEVATIONS FROM COE I" z 200'
TOPOGRAPHY, 1978.
6. SECTION COINCIDES CLOSELY WITH DIVIDE
BETWEEN SUSITNA RIVER AND TSUSENA CREEK
DRAINAGES. THIS SECTION REPRESENTS
NARROWEST RELICT CHANNEL WIDTH WHERE
GROUND SURFACE IS ABOVE MAXIMUM POOL
ELEVATION.
7. SECTION LIES ON DAMES AND MOORE SEISMIC
LINE OM-A AND QM-B, 1975.
8. SEISMIC LINE ELEVATIONS CORRECTED AS PER
COE SURVEY AND NPAS AIR PHOTO MAPS, 1978.
9. REFER TO TABLE 6.1 FOR SEISMIC VELOCITY
AND MATERIAL CORRELATION.
10. SEE FIGURE 6.32 FOR STRATIGRAPHIC COLUMN
AND GENERAL NOTES.
SCALE ~0 ........ ~2~0~0i;;;;;;;;;;;i4~00 FEET
FIGURE 6.31
0 0 0 0 0 0
0 o_ 0
.; w ..
~ ~ ~ ~ ~ ~
w w w
N3,2:52,000
N 3,234,000
N3,238,000
0 0
0 0
" 0
N 6
~ ~
~ ~
w w
WATANA
RELICT CHANNEL S. BORROW SITE D
STRATIGRAPHIC FENCE DIAGRAM
SHEET I OF 2
0 0
0 0
0 0
.; .;
" " ~ ~
w w
SCALE
SCALE
0~~~2iii0iiiiii0iiil40 FEET-VERTICAL
~0 ~~40iii0i;;;;;;;;;;;iii800 FEET-HORIZONTAL
FIGURE 6.32
N 3,230,000
N 3,232,000
DR-22
N 3,234,000
N 3,236,000
N 3,236,000
0
0
:}
;!'
w
CONTINUES TO
493.6 FEET
g
0 .;
~
w
0
0 q
~
w
WATANA
GENERALIZED STRATIGRAPHIC COLUMN
BORROW SITE D AND RELICT CHANNEL
COLUMN UNIT'
D -SURFICIAL
h</i:',':.q C OUTWASH
1+·~;,;] D
[!,<;.j E
a
F
ALLUVIUM a
FLUVIAL
DEPOSITS
OUTWASH
ESTIMATED DESCRIPTION'
THICKNESS•
0-5'
0-18'
12' AVERAGE
0-15'
0-35'
IS' AVERAGE
BOULDERS, ORGANIC SILTS AND SANDS.
SILTY SAND WITH SOME GRAVEL AND OCCASIONAL COBBLES.
USUALLY BROWN,BECOMES GRAY IN LIMITED AREAS. THICKEST IN
NORTHERN PORTIONS OF AREA. THINNING SOUTHWARD, OFTEN
ABSENT NEAR SUSITNA RIVER.
SAND WITH SOME SILT, OCCASIONAL GRAVEL. GENERALLY BROWN,
FOUND ONLY ALONG COURSE OF LIMITED DRAINAGE CHANNELS
FORMED IN OUTWASH E. GENERALLY SORTED.
SAND, SILT, GRAVEL AND COBBLES, PARTLY SORTED, WITH FRAGMENTS
SUB-ANGULAR TO ROUNDED. SILT AND SAND LENSES OFTEN PRESENT.
BROWN TO GRAY BROWN WITH A COBBLE/BOULDER ZONE OFTEN PRESENT
AT THE BASE OF UNIT F. CONTACT BETWEEN E a F IS OFTEN POORLY
DEFINED.
TILL/WATERLAIN G -50' CLAYEY, SILTY SAND, USUALLY GRAY, OFTEN PLASTIC. CONTAINS COBBLES
AND GRAVEL IN MANY AREAS. OCCASIONALLY PRESENT AS A LACUSTRINE
DEPOSIT SHOWING LAMINATIONS AND/OR VARVES. GENERALLY A TILL
TILL IG' AVERAGE
WWifU:}2J H ALLUVIUM
-I TILL
a
J
[{//::;:\ J' ALLUVIUM
~ K ALLUVIUM
BEOROCK,DIORITE
NOTES
DEPOSITED THROUGH OR NEAR STANDING WATER.
0-40' SAND, SILT, GRAVEL, PARTLY TO WELL SORTED. OFTEN ABSENT BETWEEN
UNITS G a I . UNIT REPRESENTS PERIOD OF MELTING PRODUCING
ALLUVIUM /OUTWASH BETWEEN THESE DEPOSITS. APPEARS AS NARROW
BANOS REPRESENTING CHANNEL FILLINGS. THICKEST IN WESTERN
PORTION OF THE AREA.
10' TO 65' POORLY SORTED SAND, SILT, GRAVEL AND COBBLES, OCCASIONALLY WITH
>GO' AVERAGE CLAY. GENERALLY GRAY TO GRAY BROWN. CONTINUITY UNCERTAIN DUE TO
LACK OF INFORMATION AT DEPTH. SILT OR SAND LAYER 21NCHES -6 INCHES
THICK OFTEN FOUND IN CENTER OF UNIT I. BASE UNIT ON TOP OF BEDROCK,
EXCEPT IN BURIED CHANNEL THALWEG. CONTACT BETWEEN I a J OFTEN
POORLY DEFINED, AND LOCALLY INCLUDES AN ALLUVIUM DESIGNATED J'
TO 160' SAND,GRAVEL,COBBLES,BOULOERS, FEW FINES, PERMEABLE. FOUND ONLY IN
THALWEG OF BURIED CHANNEL. TOP AT '29G FEET, EXTENDING TO ROCK AT
454 FEET IN DEPTH IN DR -2'2.
l. EXPLORATION LOCATIONS SHOWN ON FIGURES 5.1 AND 6.40.
Z. FOR LEGEND OF SYMBOLS SEE FIGURE 6.33
3. EXPANDED SECTION FROM DR-13 THROUGH DR-'20 SHOWN ON FIGURE 6.33.
4. LETTERS USED TO DEFINE UNITS ARE ARBITRARY AND WERE USED FOR
CORRELATION PURPOSES.
5. THE ACCURACY AND THICKNESS OF SOIL AND ROCK STRATA IS SUBJECT
TO VERIFICATION.
6. THIS FIGURE IS GENERALIZED FOR GRAPHIC PRESENTATION. FOR MORE SPECIFIC
INFORMATION REFER TO TEXT AND BORING LOGS.
SCALE ~0""""""~2~0iiiiiiiiiiii40 FEET-VERTICAL
SCALE ~0""""""~4~0ii0i.iiiioi8ii00 FEET-HORIZONTAL
RELICT CHANNEL 8c SORROW SITE D
STRATIGRAPHIC FENCE DIAGRAM
SHEET 20F2 FIGURE 6.32
2400
2300
2200
ti
~ 2100 !;
" 0
~
~ 2000
~
1900
1800
_045o....._..., AZIMUTH ----..-zzso
OF SECTION
WATANA
RELICT CHANNEL-EXPANDED THALWEG SECTION
2400
2300
2200
2100
2000
1900
1800
1700
LEGEND
LITHOLOGY'
~<,·,:;,yrj c
hi::f:W/ E,F
t'"''''"' G Wif&t¥1 H
CONTACTS'
-I kt:,;:./ J' -
KNOWN UNIT CONTACT
INFERRED UNIT BOUNDARY
~ BEDROCK SURFACE WHERE DRILLED.
NORMAL MAXIMUM OPERATING LEVEL EL.2185
BOREHOLES•
DR-26 COE ROTARY CORE BORINGS IJ-NOTED AS FROZEN DURING DRILLING
NOTES
SEE FIGURE 6.32 FOR STRATIGRAPHIC COLUMN AND
GENERAL NOTES.
2. SEE FIGURE 6.31 FOR TRUE SCALE SECTION OF SAME
GENERAL AREA.
3. VERTICAL TO HORIZONTAL SCALES !5 t I.
4. PERMAFROST DATA (TEMPERATURE PLOTS ON
FIGURE 6.2Bl.
DR-13 NO TEMPERATURE DATA
DR-20 NO PERMAFROST
OR-22 FROZEN 72' TO 110'
DR-26 FROZEN 19' TO 55'
OR-27 FROZEN O' TO 44'
5. BEDROCK ELEVATIONS BASED ON SEISMIC
REFRACTION. DATA (FIG. 5.1)
6. THE ACCURACY AND THICKNESS OF SOIL AND ROCK
STRATA IS SUBJECT TO VERIFICATION.
7. THIS FIGURE IS GENERALIZED FOR GRAPHIC PRESENTA-
TION. FOR MORE SPECIFIC INFORMATION REFER TO TEXT
AND BORING LOGS.
SCALE 0 ~~~ ... 8~0iiiiiiii~l6~0 FEET VERTICAL
SCALE 0~~.....;4~001iioiiii0.::8~00 FEET HORIZONTAL
FIGURE 6.33
2400
;:
~
~ 2000 ~
z
0
~ ~ 1600
~ ~
~
1200
2400
;:
~
~ 2000 ~
z
Q
~ 1600 ~ ~ ~
1200
150..,.____. AZIMUTH -zaso
OF SECTION
NORMAL MAXIMUM OPERATING
LEVEL EL.2185
1 SL81-16
NORMAL MAXIMUM i
OPERATING POOL EDGE
OM-A
SW-3 i
DR-22
SL8Q-2
i
lOGo-AZIMUTH _315 o
OF SECTION
1
sL 80~1
i 2400
EL 1680 2000 hTSUSENA CREEK
-------------~If:------------~®Iff{" --~II"----------.-"""'--------------------~"'lli'lli1;1,--------'=-"='-=-!.,~..-!--------
.... ----------
SUSITNA RIVER
{LOOKING DOWNSTREAM)
EL. 1500± _:_ _____________ .............
THIS AREA APPROXIMATELY
9000' UPSTREAM OF WATANA
DAM CENTERLINE
NORMAl. MAXIMUM OPERATING
LEVEL EL 2185
-~---
sw-3
i ----
SUSITNA RIVER
(LOOKING DOWNSTREAM)
EL. 1470± -' -----------"'
THIS AREA APPROXIMATELY
3000' UPSTREAM OF WATANA
DAM CENTERLINE
"THE FINS"
NOF.4.AL MAXIMUM
OPERATING POOL
EDGE
---
~ OR-20
SL80-2
i
OR-18
SUSITNA RIVER TO TSUSENA CREEK
ESTIMATED THALWEG (DEEPEST PATH )
SECTION W-17
sL 80-1
i
2400
2000 ------q-'""'' -----, ~~---------
--I ~TSUSENA CREEK
EL.I680
--------........ -----"'-~~1----~
"THE FINS" TO ·TSUSENA CREEK
SHORTEST FLOW PATH
SECTION W-16
WATANA
RELICT CHANNEL PROFILES
SCALE
1600
120 0
o~"""~·~oiioiioiiiiilaoo FEET
LEGEND
CONTACTS'
-----APPROXIMATE TOP OF ROCK
GEOPHYSICAL SURVEYS:
1600
1200
tsw-l ~~~RSECTION WITH SEISMIC REFRACTION
OM-C 1975, DAMES a MOORE
SW-1 1978, SHANNON a WILSON
SL80-I 1980, WOODWARD-CLYDE CONSULTANTS
SL 81-2 1981, WOODWARD-CLYDE CONSULTANTS
BOREHOLES'
OR-19 COE ROTARY DRILL BORING
I. PROFILE AND SEISMIC LINE LOCATIONS SHOWN ON
FIGURE 6.35.
2. SECTION ALONG OM-A SHOWN ON FIGURE 6.31.
3. VERTICAL AND HORIZONTAL SCALE EQUAL.
4. SURFACE PROFILE FROM I"= 200' TOPOGRAPHY,
COE 1978 TOPOGRAPHY GENERALIZED TO .±25 FEET.
5. TOP OF ROCK NORTHWEST OF SLS0-1 IS PROJECTED
UP TO 300 FEET TO PORTRAY ACTUAL THALWEG PROFILE.
FIGURE 6.34
~ §~ ~ § .. § §i g
:&, "'
., N· 51' * \1)' .,. ~: ~ . ,_ ~· ..... ,_ ,...
Uf w: w "' w: w:
/~ ··--.,_,
/
!U2.2..4.QQQ.
.,-../ ....... ~-;;.:"::.~.
/' .......-ft'/_...,. •. -
/ \-
N 3,234,000
· ......... -·,
_JU~~
(
~\
~I 0 /''-
\
\
;----)
'/
OM-A 8 B ...
Q. § §! ... N' ol
" It ~· .... ....
u.l i "' w•
,~#
-I
,t
I
I
WATANA
OAM
_ .... :-___:;. ~---~
SUSI-IIA -_')
,r--"'-Rl\lf.
1 DEVIL
<;ANYON
OAIII
\, -/.
LOCATION MAP 0~~~~4'iiiiiiiiiiiiiiiiiiii~8 MILES SCALE '-
-i9\.)0.
\boo
1700.
60Q \
'~0
-------------------------------------1
LEGEND
TOP OF BEDROCK, CONTOU R INTERVAL 50 FEET,
50 FOOT CONTOURS DAS HE D.
TOP OGRAPH Y, CONTOUR I NTERVAL 100 FEET.
---...... POTENTIAL CHAN NEL THALWEGS
Wt·IG W.t·IGPROFILE OR CROSS ·SECTION LOCATION (SEE
NOTES I AND 2 )
NOTES
SECTION DM·A AND 8 SHOWN ON FIGURE 6 .31.
2. PROFILES W-16 A ND W ·l7 SHO WN ON FIGU RE 6.34.
3. DETAI L ED STRATIGRAPHIC FENCE DIAGRAM SHOWN ON
FIGURE 6 . 32.
4 . DETAI LED SEISMIC LINE SECTIONS SHOWN IN APPENDICES
HAND I .
5. RE LICT CHANNEL PHOTOS SHOW N ON FI GURE 6.30.
SCALE O~~~l,jjO~O~Oiiiiiiiiiiiiii2~000 FEET
FIGURE 6.35
QUARRY
SITE A
BORROW
SITE F
c
WATANA
BORROW SITE MAP
SCALE ~0==~·--~8 MILES
LOCATION MAP
LEGEND
L::S~:3 BORROW I QUARRY LIMITS
NOTE
I. MAP INDEX SHOWN ON FIGURE 6.1
SCALE Ob=~-~2 MILES
FIGURE 6.36
t'.3.232,000
--------/
"'-'' }' \'\.j' I
\ / r
\.;
0
0
~
"' "' "
/
/ ~I
/ /
/ /
,/ /
REFERENCES• BASE MAP FROM COE,I978-1"•200' WATANATOPOGRAPHY,SHEETS 14 815 OF 26,
COORD IN ATES IN FEET, AL ASKA STATE PLANE (ZO NE 4).
1600
16 0
'l'
0
CD
.J
"'
'
0
0
C>.
/
/
' '
2300
2200
/
SLB I-19
0
8 ,..,
"' ,._
w
0 • ._ AZ I MUTH ~ISO•
OF SECTION
8f!OO FPS
9,000FPS ··· ... --,,, __ ,-------,, ~
'-------23,000FPS ',........__ ·.
12,500FPS
SECTION SLS0-8
WATANA
QUARRY SITE B PLAN AND SECTIONS
0
0
0
"
/ 0
16,500FPS
1900
18 00
1700
1600
LEGEND
CONTACTS:
---QUARRY SITE LIMIT S
---BEDROCK OUTCRO PS
GEOPHYS I CA L SURVEYS:
-:'\5L 6I·B SEISMIC REFRACT ION SURVEY EN D OR TUR NI NG POINT-
1960-81, WOODWARD -CLYDE CONSULTAN TS
12 ,000
FPS
NOTES
SEISMIC VELOCITY CHANGE
SEISMIC VELOCI TY IN FEET PER SECOND
I. SECTION LO CATION SHOWN ON PLAN.
2 . QUARRY SITE IS SHOWN ON LEFT HAND PHOTO,FIGURE 6 .30
3 . CO NTOUR INTERVAL 25' TRACED FROM REFERENCED BASE
MAP.
4. SECTION LIES ON SE ISMIC LINE SL80-8 (APPENDIX H,
FIGURE 10).
5 QUARRY SITE B LIMITS BASED ON QUARRY SITE
LIMITS PROPOSED BY COE, 1978. LIMITS OF ROCK
OUTCROP MAPPED BY COE.
6. QUARRY MATERIAL IS OIOR ITE OUTCROPS WITH SOME
PHYLLITE,CONGLOMERATE AND BASALT AT LOWER ELEVATIONS .
OVERBURDEN IS TILL AND OUTWASH,SEE BORROW SITE D,
FIGURE 6.40 .
7. ENTIRE QUARRY SITE LIES W ITHIN PROPOSED RESERVOIR LIMITS.
8 SE ISM IC REFRACTION DATA SHOWN IN APPENDIXES H AND I.
9 REF ER TO TABLE 6 .1 FOR SEISMIC VELOCITY AND
MATER IAL CORRELATION .
SCA LE 0~~~2~0~0iiiiiiiiliiii4~0 0 FEET
FIGURE 6 .38
N 3,21S,OOO --
N 3,220,000 --
N 3,222,000 -·-···-
0
0
0.
~
w
1--!---
\
\
\
\
" \
\
\
\
\
0
0 o.
~ .,. ....
w
QUARRY A PLAN
REFERENCE : 1" o 200' TOPOGRAPHY 19 7S COE, ( NPAS) SHEET S/26.
1" • 400' TOP OGRAPHY 19SI AAI, (NPAS) SHEET I OF I, FLT. N0.4-4 .
0
0 q .,. .,. ....
w
___ ,..
X
2404
)
/
/
0
0
0.
"' ~
w
--~ ...... -~
/
'
;
/
2600
f-
~ 2500
lL
z
Q
f-:i! 2400
~ w
2300
2600
f-w 2500 w
lL
z
0 ;::
:!! 2400 ~ w
2300
o•-AZIMUTH --lso• OF SECTION
ANDESITE PORPHYRY a DIORITE
. I __________________________________________ j
SECTION D-0
0 AZIMUTH 0 ......_OF SECTION-lso•
ANDES ITE PORPHYRY a DIORITE I
I
__________________________________ __j
SECTION G-G
QUARRY SITE
+
SCALE 0~~~4~0~0~--~S~OOFEET
LEGEND
STRUCTURE
SUSPECTED FRACTURE ZONE WITH LOCAL SHEARING
~ BEDROCK OUTCROP
SHEAR ZONE
CONTACTS
----MAPPED LIMIT OF BORROW SITE
OTHER
D D
t.t
NOTES
CROSS-SECT IO N LOCATIONS
SAMPLE LOCATION (APPROXIMATE)
I. SELECTED TYPICAL SECT IONS SHOWN .
2. VERTICA L SCALE 4 TIMES HORIZONTAL SCALE .
3 . 50 FOOT CONTOURS REPRODUCED FROM REFERENC ED
BASE MAP.
4 . CONTOUR INTERVAL 50 FEET
5 . QUARRY SITE LIMITS BASED ON PRELIMINARY MAPPING AND
IS SUBJECT TD RESULTS OF DESIGN E XPLORATIONS.
6. INTERPR ETATION BASED ON AIR PHOTO INTERPRETATION AND
RECONNAISSANCE, AND SURFICIA L GEO LOGY MAPPING.
7. PHOTO TAKEN AUGUST, 19SI.
S. LITHOLOGY AND CONTACTS WITHIN QUARRY A REQUIRE
FUTURE DELINEATION
FIGURE 6.37
E 74~,000
E 735,000
BORROW SITE C
BORROW SITE C
REFERENCE ' BASE MAP FROM USGS 1'63,360 ALASKA QUADRANGL E, TALKEETNA
M OUNTAINS (0-3)
COE, 1976
s 8 w' 1978
COO RDINATES IN FEET, ALASKA STATE PLANE (ZONE 4 )
81 ~I ~~
LOWER BORROW SITE F
UPPER BORROW SITE F
WATANA
BORROW SITES C 8 F
LEGEND
CO NTA CTS'
---MATERIAL LIMITS
BOREHOLES AND TEST PITS '
-TP-6 1978,COE TE ST PITS AND TREN CHES
GEOPH YS I CA L SURVEYS ,
8 SW-9 SEISMIC REFRACT ION SURVEY
END OR TURNING POINT-1978, SHANNON 8 WILSON
NOTES
I. CON TOUR I NTER VAL 500', TRACED FROM ENLARGED
REFERENCED BASE MAP.
2. BORROW SITE LIMITS BASED ON SEISMIC AND AIR PHOTO
INTERPRETATION. FI NA L MAPPED LIMITS OF BORROW MATERIALS,
SUBJECT TO RESULTS OF DESIGN IN VESTIGATIONS.
3. BORROW M ATER I AL IS COMPRISED OF CL ARK AND TSUSEN A
CR EEK HISTORICAL AND RECE NT TERRACE DEPOSITS OF
GRAVEL AND SAND .
4. ENTIRE BORROW SITE LIMITS LIE OUTSIDE OF PROPOSED
RESE RVOIR LIM ITS .
5. EXPLORATION LOGS AND SEISMIC LI NE SECTIONS I N CDE,
1976.
6. SEISMIC LINE LOCATIONS REPLOTTED F ROM SHANNON 8
WILSO N, 1976 LOCATIONS APPROX IMATED.
7. PHOTOS TA KEN SUMMER OF 1976 AND 1961.
0 2000 4000 FEET
SCALE
FIGURE 6.39
·-___ .---! ~ ___ _,-'------/.....--..____. TP·IO
.{JAP-21
TP-9
®AH·D-6
PLAN
BORR OW S
GEOPHYS ITE LIMIT
ICAL SURVEYS •
. SW-3 SEISMIC REFRACTION
OM· A 1975 SURVEY END SW· , DAMES a MOORE OR T URNING POIN T
3 1978, SHANNON a
SL 80· 8 19 8 0 WILSON ·8 1, WOODWARD
BOR EHOLES AND TE ·CLYDE CO NSU LTAN TS
8 DR·27 1978 COE RO ST PITS• ' TA RY DRI
® AP-21 1978 CO E LL BORING
,.,.. , AU GER BO
"'-' AH-D-12 1980 RING 'AAI AUGER
-TP-11 1978 C BORING • OE BACKH
• BULK SAMPL OE TEST PIT
E LOCATION
___ .:._F~IG,vURE 6.40
-~1
U.S. Standard Sieve Openings In lnohes U.S. Standard Sieve Numbera
----I I ~ ~ ~ ~ ""'"\ I" l\"' ~"' ~""' ~ I.! I' "~ -~ ~ ~ t--1'-"" -~-
100 12 9 6 3 2 11/:i! I 3/4 1/2 3/8 4 10 20 40
1\~'-:\ \:' ~ ~""' ~ "~ ~ 0 ~~ ~ ""'""' " "-t"-. ~ ~ ~ f---
~ "-.:
'"""
~'\
!"-.._ ""'""' ""'-
"I"-['-.._ ~ ~ ~~~ " "-"'-!~ ~ !"-..'\ 90 ,, ~ ~ "'~ ~ ""'~ " "['-.._ "-['-.._"' ~'\ !"-.._""' ""'"-.._ "-I"-~ :-\ ~ "-
-~ 0 ~!"-.._ l"-..~""' "-"" "-~ ~~ ~ "'""' "-'"' ~"\: -
80
\ 0: ~ ~""' "\: "'['-. !"-.._ f'-.."-~'\ ~""' ""'"-"" 1"--""'-~ ""'""'" ~ ~ ~""v " 1"-" L"-~ ["-.._~ ~""' ~ "-~'-"' ;: ~'\ "' \.~ ~""' ~ "" 1'-l'-. :\ ~ ~""" ~""' '0 "" ,"-~ "'-~ "' ~ ~'\..~ "'['-. ~ l0 L"-....~ ~~'\ "['-. ~ ~ ~'\
70 -.r:;
00
Ql
~ 60
>-
-~ " "':'-.. [\ t'\ ~ ~""' ~ ""-"-"" 0 ~ ~-~
' "" 1'-i'-. "-; ~ ~'\ -"'""'""' '\
~'-."-[\ ~ ~
.0
.... 50 Ql
c: u:
~~ ~"' -:; ~ ['-.._~ ~""' ~ "'"' "' ~ ~'\
~-[\ ~ ~""" ~ ""'""' "-
1'-" ."-~ ["-.._~
iV ~ ['-.._~ ~""' ~ ""' "-"' "-"' ~'\
~ ~ ~""'~ " " ~ ~ ["-.._~ "'"-
-c: 40 ~
~ a.
30
\ t"-....~ ["-.._""'""' '\ 1"-:'-.. [\ "' ~"' ~ ~""'~ ""' "-~ 0 L"-.."'\ 20
\ ~""' ~ 1"-:'-.. [\ ~ ~
~ ~"-"-'\ 0 ~'\ 10
1::::..:'\. I"-"'--"'-L__-~-0 1000 !500 100 !50 () !5 0.!5
COBBLES Medium Fine
GRAVEL SAND
Coarse Fine
TOTAL NUMBER OF SAMPLES:I46
WATANA
BORROW SITE D
RANGE OF GRADATIONS
'l -1 ~ ' ) ----l ~-----1 -1 ~-l ~ -]
Hydrometer
~~~ -
~" "-l\ ~ "' ~
10 100 200 270 0
~""' ~ 1'~'-"'~ ~ ~ "'""' ""'~ r-
~ ""'"-.._ ~'-" "-l"-"' ~"' l"-.._"" '0 ~ ~ 10
~""'~ ['. "~ :\ ~~ """'""' '\ "'" [\ ' "
['-.._ ""'""'"' ~" "-l"-:.; ~"' ~""' ~ ""' "' "'" ,'\ t\.
20
~""'~ ""' :'--. 0 ~'\
""""'""' ""'-
'-.["-. "-[\ ~ ~
~""' "'-0 "" "-:\ ~ ~ ~""'""\ " "-~'-~ 0 ~'\ ~
"'""'""' ~ "" ['-. "-; ~ ~""'-~ ""'""'"' "" ['-. ~ ~ ~ ~~
l"-.._"" ~ "" ""-~ ~~ ~""' ~ "" ["-. "'-
"'"""
~'\ !"-.._""' "-
30 ..
&.
~
'i
40 3t ,..,
.a
"'""' ""'"-.._
~"-"' ['-. [\ ~ ~ "'-~""' '0 " "f\.,. ~ ~ ~ ~
~""' ~ "'["-. -~ r0 ~~ ~ ""''\ '-.._['-. ~ ~ ~'\ ~
L"-...."" ~ ""' "~ D: ~ ~ ""'~ " '-.._['.._ ~ :\ ~~ ~"' ~ ""'~ 1'.1'-. "' r'0 ~'\ ['-.._""'""'"'
['.1'\. "-~ ~ ;0 ~~
~""' v "-~'-1"--"' t\ ~~ ~""' ~ "['. "'"' "" "'"""
~'\ """"' '\ ~~~ '-~'-"-~ ~ ~'\ ~~~ "I" ~ -"' :-; ~ ~~
...
ro • Ill ~
0 0 u so .. c
II u .. • 70 a.
~""' ""'" " "' "-~ "'-~ "'""'""' '\
['.['. ~"-"-I'\ "-"' ~ "'-l"-.._~
~ ""''\ "-~'-"-~ ~ ~'\ ~""' ~ I'. I'-~"-" "-~ """"\ ~'\ 80
~""'~ 1'-" "-~ 0 ~~ ['-.._""' ""'"-.._ ~'-" "'"-~ "'-""' ~ ~~
!"-.._""'""' '\ ~" "-:\ ~ ~"-~""'~ ['.
"'"-~ ~ "-~ ~ ""'-90
""" "'-. '\ ""' "-!'\_""" 0.._'\ ~""' ""''\ ~'-" "'"' ['-.._ ~ ~"' ~~
01 0.0!5 0.01 0,005
FINES
Silt Sizes
FIGURE 6.41
)
100
90
80
-..c:
01
G>
3: 60
1-~ 50
LL
20
1 ' - 1 1
US. Standard Sieve Openings in Inches U.S. Standard Sl••• Num~ra
BOULDERS COBBLES
GRADATION
TYPE
GRAVEL
Coarse Fine
MATERIAL
SILTY CLAY, CLAYEY SILT WITH SAND
~:::>'{~>.>J 2 SILTY CLAY WITH SAND AND GRAVEL
[::){::~:;:~d 3 SILTY SAND WITH GRAVEL
NO. OF SAMPLES
14
24
9
Medium
WATANA
SAND
Fine
BORROW SITE D
MATERIAL GRADATION TYPES
SHEET I OF 2
) ] ---1 l
Hydram•t•r
0
10
20
30 ...
~
01 •• 40 ~
.... ,g ...
!50 .,
"' ...
CJ
0
0
60 c
C)
~ .,
70 ll.
80
90
0001 100
FINES
Silt Sizes
FIGURE 6.42
' 1 l
U.S. S1andord Sieve Openings in Inches U.S. S1ondard Sieve Numbers
a..
100
90
70--·--·---------
-----------
-----,---1---+Hrl-1-+--+
10
--1----+---+---+-++-+-+-+--+---+--+-----
O IOL100-"_j_-L_J5c_OO . .J___L_-'--__ __JIOO ,_ i____L__jL___L __ ---
10 50
I BO~DERS COBBLES
GRADATION
TYPE
GRAVEL
Coarse Fine
MATERIAL
• 0 ... ·•• 4 ~}3. '0'
SILTY SAND WITH CLAY AND GRAVEL ... · ..
SILTY SAND WITH GRAVEL
GRAVELLY SAND, SANDY GRAVEL
'-'-~ -------------~
5 I 0.5
SAND --
Medium Fine
NO. OF SAMPLES
41
8
50
WATANA
BORROW SITE D
MATERIAL GRADATION TYPES
SHEET 2 OF 2
l ., -1 --l 1 -.. ] ~ -1 -l 1
Hydrometer
' --,----.-.-----0
t-+---t-+--+--i 10
-
20
FINES
Silt Sizes
FIGURE 6.42
~ 8 8 0 0 .; ~ ..... ..... .... .... .., ..,
N 3,20!4,000 + r-
!NOTE: TEST PITS Rl2 THROUGH Rl4 LOCATED ON
TH ESE TWO ISLANDS AND NEXT ISLAND
UPSTREAM SHO WN ON PH OTO.
~~-r-TP-RI~~------+ N 3,226,000--=-'· . ...__
' "'----· ---"'------·-.
. --.:;, ----·-----" --·
+
REFERENCES: BASE MAP FROM COE,197B -I" •200' WATANA TOPOGRAPHY,S HEET 6 a II OF 26
R aM,I9BI -I" • 40D' DEVIL CANYON RESERVOIR MAPPING,FLIGHT
5 (6-8),MANUSCRIPT 2
COORD INATES IN FEET, ALASKA STATE PLANE (ZONE 4)
0 0
0.
"' "' .... ..,
t
AH -E4 TP-E 17 ~
... ~ ' . ...
'·./ ',
0
0
0
0
"' .... ..,
--
I
/
WATANA
BORROW SIT E E PLAN
0 0
0 ,;
"' ... ..,
/
/
_ _./
./
__./'"
-~
..
8
0 .;
N ....
w
/
oc> / ......
/
/
TP·2 -
AH -E I
•,
1. TYPICAL SECTIONS AND PHOTOS ARE
SHOWN ON FIGURES 6.44 AND 6.53.
2 . CONTOUR INTERVAL 25', TRACED AND/OR
REDUCED FROM REFERENCED BASE
MAPS .
3 . "sw• SEISMIC LINE LOCATIONS CORRECTED
AS PER S a W ORIGINAL SURVEY NOTES,
1980-81 LOCATIONS PER RaM SURVEYS.
4 . MATERIAL LIMITS BASED ON FIELD
EXPLORATION, MAPPING AND AIR
PHOTO INTERPRETATION. FINAL
LIMITS OF BORROW MATERIALS
SUBJECT TO RESULTS OF DESIGN
INVESTIGATIONS .
5. BORROW LIMITS EXTEND TO SOUTH SHORE
OF RIVER, AND ADJOIN BORROW SITE
I (FIGURE 6.51) ON WES T END.
6 . NORTHERN PORTION OF BORROW SITE
EXTENDS ABOVE PROPOSED DEVIL
CANYON RESERVOIR LIMITS (1455'1.
7. EXPLORAT ION LOGS AND SEISMIC
LINE SECTIONS SHO WN IN APPENDICES
F, HAND L .
'·-~SW -1 4
CO NTACTS:
----MATERIAL LIMITS
BOREHOLES AN D TEST PI TS
®AH-EI 1980, AAI AUGER BORING
• TP-5 1978, COE BACKHOE TE ST PIT
-TP-E3 19 81, AAI BACKHOE TEST PIT
TP ·RI3
GEOPHYS I CAL SURVEYS'
SW-12 1978,SHANNON a wiLSON
SL80 -9 1980-81, WOOD WARD-CLYDE CONSULTANTS
OTHER:
SW-10 SW-10 t A CROSS-SECTION LOCATION J ( SEE NOTE II
SCALE 0~~~4~00iil;;;iiiiiiiiii8~00 FEET
FIGURE 6.43
2000
;::: 1800
w w
!!;
z 1600 0
i=
:;! w
__J w
1400
1200
,_
w w
"'-
2000
1800
i5 1600
i=
:;!
w
__J
w 1400
1200
TEST PIT TP-E15
SOUTH WALL SHOWING BOULDER LAYER
OVER SANDY GRAVEL
003.-AZIMUTH _183•
OF SECTION
SEC TION SW-10
320._ AZIMUTH _140•
OF SECTION
SECTION SW-14 a SLB0 -9
TEST PIT TP-EI 5
SAMPLE I-WEIGHING a SPLITTING
WATANA
BORROW SITE E SECTIONS
2000
1800
1600
1400
1200
2000
1800
1600
1400
1200
TYPICAL STREAM-WASHED GRAVEL
SUSITNA FLOODPLAIN, WESTERN SITE E
0~~~2~0~0~-~400 FEET SCALE '-
LEGEND
CONTACTS'
-----APPROXIMATE TOP OF ROCK
GEOPHYSICAL SURVEYS'
6 SW-IO SEISMIC REFRACTION SURV EY END OR TURNING I POINT
SW-10 1978, SHANN ON 8 WILSON
SL 80-9 1980, WOODWARD-CLYDE CONSU LTANTS
SE ISMIC VELOCITY CHANG E
1 }~~0 SEISMIC VELOCITY IN FEET PER SECOND
NOTES
SECTION LOCATIONS SHOWN ON FIGURE 6.43
2. ALL SECTIONS LOOKING UPSTREAM (EAST).
3. VER TICAL AND HORIZONTAL SCALES EQUAL .
4 . SECTION ELE VAT IONS FROM REFERENCED BASE MAPS,
TRACED AT 25' CONTOUR INTERVALS .
5. ADDITIONAL PHOTOS AND SKETCHES OF TYPICAL BORROW
SITE CONDITIONS SHOWN ON FIGURE 6 .53
6. ZONES IND ICATE MATERIAL TYPES AS DESCRIBED IN
TE XT. INFERRED ORIGINS ARE •
I . SUSITNA RIVER ALLUV IAL GRAVELS
JI. TSUSENA CR EE K BED ALLUVIAL GRAVELS
:m:. OUTWASH OR HIGH LEVEL HISTORI C GRAVEL 8
SAND TERR ACES
7. SECT ION S LIE ON SHANNON 8 WILSON 1978 SEISMIC
LINE S, COE 1978, AND S 8 W 1978 .
8. REFER TO TABLE 6 .1 FOR SEISMIC VELOCITY
AND MATERIAL CORRELATION.
9. PHOTOS TAKEN APRIL, AUGUST 1981 .
FIGURE 6.44
1
100
90
80
70 -~
(II
Ill
~ 60
"" .0 ,_
50 Ill c:
u.., -c: q() ~
~ a_
30
20
10
US. Standard Sieve ~ln9• In Inch .. . U.S. Standard Sieve Nlllftber a
I 9 6 3 2 11/2 I 3/4 1/2 3/11
~'\ ~""""\ '\
[', ['," ~ [',_~ ~"""""" ~ ~'-"'-
~ ~~""" "~ ['\ ~ ~ ~""' "0 ~'-""--~ ~""'~ "-f"-~ 0.: [0"\ r0"' ""'~ "['-, "' ~"\ ~""' "'0~ "" ·""' r\: ~ ~""'~ ~'-"'-~ ~ ""''\ "" ['-,
'""' "'"" ~""" ~ ~""'"" ~'-"'-
~""" ~"'y "" ~ ·""' l\: "'-.~ ~""' ~ """ '""'~ ~""' """" "-~"' ~ ~ ~""' ~ ""'""'""'
"!'-·" ~ ~""~ " ~ 0 ~ I"'~ ~ ""~ ""' ~~ ~""' """"'
"-I""--~ ~ ~ ~""'~ " "" ~"" ~ "-f"-~ r0 0."\ ~~""'""' ""'-
'"" v "'" ~ ~ ~ ~ ~""'~ "" "~ "'" "" ::; ~ ~"" ~"" y "" "' ~ ['-,
" "" [\ ""'~ """" ""''\ '-_f'-,
~'~~r-. '-~"-~ ~" ~""' ~""'""'" " ~
......... ~ ~"\ ~"" "\ ~" ['-,
~ ~~" '\L
.... 1'-~:::: ~
I
!500 100 D
BOULDERS COBBLES
GRAVEL
Coarse Fine
TOTAL NUMBER OF SAMPLES: 50
4 10 20 40
~ ~ ~"" ~""'""'" "
~ ~ ~
~ 0 ~~ ~ ""'~ ""' ~ ~ ~"\
""'
["-, ~" ~ """""'" """ " ·"" [\ ""'~
" ~ ~~
""'""' ""'"""
"'"" ~ ~
"'""'""' ,0 ~ 0"0 ~""' "\ ~"" [', 2\ [0"\
~ '"' ~"\
""'""'""'"' "'"' ['\ ~ ~
·" ~ ""'~ ~ ""'~ "'" '""'
~ ~"\
[\ 0 0,"' ~""' y 1'-" " l\: ~~
~ 0 ~~ ~~~ '-I'-"' [\ "" ~"\
[\ ~ ~ ~~~ " ~ """ 0: ["-,~ ["\,
~ ~ ~"\ ~ """""
"'-~"'-" ~ ~ ~
~ 0: ~ ~""~ ~'-.["-. ~ ~ ~"\
t\ 0 ~"" ~""" ""'" "" L"' ~ ~~ ·" ~ ""'~ ~""'~ "~ " 0 ~""" ~ ~ ~" ~""' "0 "" ·""' ~ "'""\ "" b,. 0 :"-."\
"""' ""'""
"~ :\ 0 ~"' ~ ~ ~ ~""'"\ ['\.. "" 2\ :"-.~ -~ f'"\, ~ :\ :"-. ~"'
1'---~ ~ ·""' ~~ -~
0.!5
SAND
Medium Fine
WATANA
BORROW SITE E
RANGE OF GRADATIONS
l -l
Hydrometer
110 100 200 210
I I I' .....
~~
~""'~ ~"""~ ~""'""' "\ ~""'~ ~"""" ~""' ~ ~""" y r-
~ """"" ~""'~ ~v
0.. ""''\
:"-.""' ""'" I'
~ ""'~ ~""'~
'""' ""'""" ~""'~
""""' ""'""" ~ ~""" ~
Ql 0.0~ 0.01 0 .()05
FINES
Silt Sizes
FIGURE 6.45
0
10
20
&>
.,
~
1...-..
1-
70
80
90
-~
Cll
I
l' .. • • g
u .. c • ... ... • ll.
-.c
0>
QJ
3:
"" .a
....
QJ
c
IJ._
~
~ u
;;j
(L
... 1
U.S. Standard Sieve Openifl9s in Inches U.S. Stondord Si.,e N11mber s Hydrometer
100 12 9 6 3 2 11/2 I 3/4 1/2::5/8 4 10 20 40 80 100 ZOO 270
90 I I l
I ! I j
! . I I
80
! I ~ I i ·~ :l I i I
70
I II i i
601
I I I i
50 l
40
1 30
I i
I
20
I
10
r 0 1000 500 100 Ql () 5 0.5 0.05
BOULDERS
GRAVEL SAND
COBBLES Coarse Fine Medium Fine
} .... l
I
i
i
I
0.01 0.005
FINES
Silt Sizes
) l
0
10
20
30
40
50
f60
70
80
90
QOOIIOO
UNIT MATERIAL NO. OF SAMPLES MATERIAL NO. OF SAMPLES
~~:~:!:~:~:~:1 A SANDY SILT WITH TRACE CLAY 4 (·:i2j D SANDY GRAVEL, GRAVELLY SAND II
f:':.:";.:::.=;:;·::::j 8 SILTY SAND 10 fR)"J:Q/ E SANDY GRAVEL WITH SILT, COBBLES, BOULDERS 19
/.:·:>>;:<:J C SILTY SAND WITH CLAY, GRAVEL,COBBLES 6
WATANA
BORROW SITE E
STRATIGRAPHIC UNIT GRADATIONS
FIGURE 6.46
-J:!
al
ii
3t
"" .Q ... • .. ....
0
0 u
"'i:
IU u ...
"' a.
E
00
"ii
~ ,..
..Q
\...
II> c
G: -~
~
Q_
U.S. Stondord Sieve ()plnii'IOt in lrlchU U.S. Star~dard Sieve Numbefl
100 12 9 6 3 2 11/2 I 3/4 1/2 3/8 4 20 40 10
I I '-.'\ ·"'-."'-. ~ I' I
'-. .'\.
90 ~ ~ 0: ~'\ ~~~'\ ~r--~ ~
'-I" [\ ['\ ~~" ~~~ r--"-~ ~'\: ~
80 '-.[', ~ ~""" ~"""' ""'~ ~"' "'" ·""" ~ ""\' "" ·""" l"-: <~ 0-.~~ "r--" ~ "'-" ~"""' ['-..."
70 "~ :'\ "" :\.""" ~~~""" ~ ~ 0: "~ ~~" I ,I" ~ ~ ~ """~ ~~~ "'"' ~ ['\ ~ 0..'\ ~~ ~""" [\
60
~~ ~ 0 ~ r\..~ ~" "' ['... ~ 0 :"-.~ ~~~ ~
1 .. ~ [Ito. ~ ~"""' ~ """~~~ "'" ~ ~ ~ ~ ~~~ c-... G. ~
50
~ ~ ~~~ "' ['.: ~ -0 ~~ ~~~"""' "~'--~ ~ ~ " ..... ~"'-. ['. f''-1"--~""" ~ ~ ~~~ "['., ~ 0 ~
q()
...._,~ ~" ['.: ~ ~" ~'\ ~~~ ""-l"-l"' ::\ ~
~ ~ ~ ~~ ~~"'..:. [',",
"""'
~ "" ~"""'
30
....... ~ ~~~" "~ " ~ "~ T ~ """"' ~ ~ ~"""' !
20 ""~""'-:-..... "" ,:\ ~~
...... ~ ~
~
10
01000 !500 100 0.!5
BOULDERS COBBLES GRAVEL SAND
Coarse Fine Medium Fine
TOTAL NUMBER OF SAMPLES : I 0
WATANA
BORROW SITES C 6 F
RANGE OF GRADATIONS
1 --) l --1
Hydrometer
0 10 100 200 Z70
I I I'
10
20
30 -c
01 • q() ~ ,...
4 ...
50 • .. ....
0
0 u
60 'E
II u .....
II
70 Q_
~
"""~ ~~~
~~~
80 -0.. ~ '\
r\..""~
90 ~~"" """[', ~
Ql 0.0!5 0.01 0.()()!5 QOOIIOO
FINES
Silt Sizes
FIGURE 6.47
0
8
~ 6
"' ... ....
N312.001000
N3.2051000
!!_~.2 1 0,000
BORROW SITE H
REFEREN CES: BASE MAP FROM R SM,I960-1"•2000' RESERVOIR
COORDINATES IN FEET, ALASKA STAT E PLANE (ZONE 4)
~I gJ
~I ...
"'I
0 0
0
ri ...
w
gj
~I
I
/
' --~
'-----~ -·--
I
TYPICAL BORROW MATERIAL EXPOSURE
WATA NA
BORROW SITE H PLAN
I
\ ~
I
LEGEND
CONTACTS :
---MATERIAL LIMIT
BOREHOLES AND TEST PITS :
®AH-HI 1961,AAI AUGER BOR ING
® SAMPLE LOCATION (APPRO XIMATE )
NOTES
I. CONTOUR INTERVAL 100', TR AC ED FROM ENLARGED
REFERENCE D BA SE MAP.
2.. MATERIAL LIMITS BASED ON FIELD AN D AIR PH OTO
INTERPRETATION . FINAL MAPPED LIMITS OF BORROW SITE
SU B JECT T O RESULTS OF DESIGN IN VESTIG ATIONS.
3. BORROW MAT ERIAL IS GLACI AL OUTWASH AND
T ILL OVERLYING BEDROCK . DEPTH TO BEDR OCK ESTI MATED
TO AV ERAGE 4 0 -50 FEET.
4. ENTIRE BORROW SITE L IES OUTS IDE OF PROPOSED WATANA
AND DEVIL CANYON RESERVOIR LIMITS.
5. EXPLORAT ION L OGS SHOWN I N APPENDIX F .
6. PHOTOS TAKEN AUGUST 1961 (LEFT), SEPT. 19BO (RI GHT).
SCALE O~~~I0~00~-~2i000' F EET
FIGUR E 6.48
-&.
01
" ~ ,..
..0
"-
~
u.., -c
~
~ a...
U.S. Standard Sieve Openint• in Inches U.S. Standard Sieve Number •
100 12 9 6 3 2 11/2 t 3/4 1/2 3/11 4 10 20 40
I '~ ~ K_"-~"" :\ '""''""'""
,~
""' "' I' I ~ ~
90 '\~ ~ t\: ~ ~"""' ~ ["\,'"\, '\ "'""' ~
\[""'-[""': ~ ~"" ~'""' '""'""'
" ""' ·"' ~ 0.~ ~
80 ~ ~ ~ [0.~
""''""' '""'~ ~"-""'-0. ~ ~""" ~'""''""'"" 1':: ~
l} I' ~" ~ ~'""' ~ ~ 2\ """'~ !'-.'""' '""'~ "'-L""'-~ "' ~
70 ~ 2\ ~'\
'""''""' '""'~ ""' ["'; ~ ~"" ~ "'"0 "~ l"-:\ ~
!\ ~ ~ ~'""'~ 0 ~~
""'""''""' '\
""'-L""'-t\ ~ ~""" ~r\ ['"\,
60 ~ ~""" ~'""''""' 0.
~" l0. 0,_ ~ t0.""~ f'. ""'~ ~ ~ ~~
"'~ ~ '""'~ "'"" ~ ""'-""' ~'\ ~'""''""'"" "'-l"'"'-[\ f'.-V
"""' 50 ~ ~""'"""'"' ~ ~ 0 ""~ ~ '""'~ f'. ""'-L""'-~ ~ ~~
~'\ ""\,[""\, ['\ ~ ~ '""\, ~"""' ~ f'.f'. "" ,0. \: 0.~ 1"\,
40
~ f'. [""\, 0. I"\," ~~ "''""'~ '\ f'-""'-~ t\ ~ ~""" " r-.~ ·""' l"-t\: f""\,"0 ~'""'~ f'. "-.i"--~ '"" ~'\:
30
N N ~'\
"""'""'"""""
f'." "' [\ ~ ~""
""""" ~ ~ r0 ~~ f"'-"-
20 ~~ ~ ,"'. ~-~~
r-'-~
10
0 1000 !100 100 0.!1
BOULDERS COBBLES GRAVEL SAND
Coarse Fine Medium Fine
TOTAL NUMBER OF SAMPLES : 49
WATANA
BORROW SITE H
RANGE OF GRADATIONS
1
Hydra111eter
eo 100 200 210
I
~
~ '""'~ ~'""'~ ~"""'"" I'
~~'\:
~'""' "0
I'
~"" '\f'. ' ~""~ '
~"""' '\ '
~""~ ~~"""' 0. '
-.....:::
~
Ql Q05 0.01 O.oo&
FINES
Silt Sizes
0
10
20
30
oiK)
~
,.,,...
I~
70
80
90
.. • • g
u
FIGURE 6.49 m
-l ----~ ' --1 .. --] . --J ~·-·-} , "--~
US. Standard Sieve Openinos in Inches U.S. Standard Sieve Numbers Hydrometer
100
-........ .·.
IOHY~~-+-+--+---~HH~~-+-+--~----+r~~-+~---r----+++++-r4~~--+----~+~~-+-r-+--+-----H1~~-+~--~--~90
I
BOU..DERS
UNIT
EII.:J A
[;'·~·-:_;:,•j B
F~ c
COBBLES GRAVEL
Coarse Fine
MATERIAL
SANDY SILT WITH GRAVEL,CLAY
SILTY SAND WITH GRAVEL
SANDY GRAVEL
0.!5
SAND
Medium Fine
NO. OF SAMPLES
9
30
10
WATANA
BORROW SITE H
STRATIGRAPHIC UNIT GRADATIONS
Ql 0.0!5 0.01 0 .00!5
FINES
Silt Sizes
FIGURE 6.50
II
i
BORROW SITE H SEE FIGURE 6.48
H 3 , 20::.,000
-L I
WATANA
BORROW SITE I PLAN
NOTES
I. BORROW SITE PHOTO SHOWN ON FIGURE 6.53.
2. CONTOUR INTERVAL 100' TRACED FROM 1"•1000' ENLARGEMENT
OF REFERENCED BASE MAP.
3 . BORROW MATERIAL IDENTIFIED IS RIVER GRAVEL
AND SAND DEPOSITS, INCLUDING ACTIVE FLOODPLAIN,MID-
RIVER BARS, AND TERRACES NEAR RIVER LEVEL.
4. MATERIAL LIMITS BASED ON FIELD AND AIR PHOTO
INTERPRETATION. FINAL MAPPED LIMITS OF BORROW
SITE SUBJECT TO RESULTS OF DESIGN INVESTIGATIONS.
5. ENTIRE BORROW SITE AS DRAWN LIES WITHIN PROPOSED DEVIL
CANYON RESERVOIR LIMIT S. LOCAL DEPOSITS ARE INFERRED
TO CONTINUE UP SLOPE BEYOND LIMITS SHOWN.
6. EXPLORAT ION LOGS AND SE I SMIC LINE DATA ARE SHOWN IN
APPENDIXES F AND I.
7. EASTERN LIMIT OF SITE COINCIDES WITH DOWNSTREAM
LIMIT OF BORROW SITE E AND MATERI ALS ARE CONT INUOUS
BETWEEN SITES.
8. TEST PIT LOCATIONS APPROXIMATE .
9 . TEST PITS R-12 THRU 14 SHOWN ON FIGURE 6.43( AREA E).
SCALE O~~~I0~0~0--~2~000FE ET
FIGURE 6.51
N 3,225,000 __
....
"'
REFERENCE: BASE MAP FROM R a COORDINATES IN F EE~ .. I!~~;~~· ;~~0' RE SERVOI R MAPPING TE PLANE (ZONE 4 1 .
i
"'
§
0
CD ....
"'
(
\
0
8 g ...
w
WATANA
BORROW SITE J PLAN
§
.; ... ...
"'
'~
/
/
'
'\
§
0 ... ...
"'
\
''··
f
/
'
'
·--
v
\
)
f\ .\ ,_,
'
·. ./
\ I
LEGEND
CONTACT S:
-·-· -MATERIA L LIM ITS
:REHOLES AND TEST P ITS:
TP R-1 19BI , AAI TEST
GEOPHYSICAL SUR PITS AND TRENCHES
8 VEYS:
• SL 8H SEISMIC REFRACT TURN ING POINT-I~~IN SURVEY ENO OR , WOODWARD ·CLYDE DON SULTANTS
NOTES
I . SITE PHOTOS WITH SEC TION SHOWN
2. CONTOUR INTERVAL 10 ' ON FIGURE 6.53.
ENLARGEMENT OF REF~~ETRACED FROM I ' •1000'
3. BORROW MATER NCED BASE MAP.
GRAVEL AND SA~~; IDENTIFIED AS RIVER
TERR ANCES NEAR R'lv~~ -~~~ER BARS • AND LIMITED
4. MATERIAL LIMITS BASE EL . ~~;:,R:~;~~~~0~0F~~~~L~::~~~~:~~:~RFP:~;~OW
5. ~~~~~~~ BORROW SITE L IES W I TH~~NP:L DESIGN IN VESTIGATIONS . . OPOSED RESERVOIR
6 . EXPLORATION LOGS APPEND ICES F AND I AND SEISMIC LINE DATA A · RE SHOWN IN
7. BORROW SITE COULD E ~~~~~R:~~~NA~~T~~~~~~7~~~i~~~N~~~j~~~ ~~~AR TO
8. TE S T PI T LOC ATI O ' AND E 790,000.
NS APPROX IMATE
0 1000 2000 FE ET
SC AL E
FIGURE 6.52
BORROW SITE I
(DOWNSTREAM OF WATANA)
BORROW SITE J
(UPSTREAM OF WATANA)
LIMIT
f
SECT ION LOOKING WEST IN BOR ROW ARE A E
CUT AT TSUSENA CREEK ON SEI SM IC LIN E SW-10
WATANA-RI V ER ALLUVIU M
TYPICAL SECT IO N
BORROW SITES I a J
TY PICAL RIVER DEPOSIT
(PHOTO TAK EN IN BORRO W SI TE E
UP STREAM OF SITE I
NOTE D ON TYPICAL SECTION)
WATANA
BORROW SITE S E ,I a J
PHOTOS a TYPICAL SECTION
0~~~2~00~--4~00 FEET SCA LE c
LEGEND
LITHOLOGY'
[::~~:~1 SANDS, GRAVELS ABOVE WATER TABLE.
POSSIBLE COARSER RIVER ALLUVIUM ASSUMED
TO BE TILL, PENDING RESULTS OF DESIGN INVESTIGATIONS.
~~!Oilll\ BEDROCK(DIORITE 8/0R ANDESITE FLOWS)
CONTACTS '
---BORROW LIMITS
----ASSUMED TOP OF ROCK
GEOPHYSICAL SURVEYS:
1,000
FPS
NOTES
SEISMIC VELOCITY CHANG E
SEISMIC VELOCITY IN FEET PER SECOND
PHOTO LOCATIONS 8 BORROW SITE MAPS SHOWN ON
FIGURE 6.43 (S ITE E), FIGURE 6.51 (SITE I), FIGURE
6.52 (SITE J), AND FIGURE 6 .53.
2 . PHOTOS TAKEN AUGUST 1981.
3. REFER TO TABLE 6 .1 FOR SEISMIC VE LOCITY AND
MATERIAL CORRELATION.
4 . VERTICAL SCALE 2 TIMES HORIZONTAL.
FIGURE 6.53
100
90
80
70 -.c
Qt
Ill
3:: 60 ,...
.a
..... 50 Ill c: u: -c: 40 ~
~ a..
30
20
10
-. J l .l 1
U.S. Standard Sieve OpeninQ1 In lncllel U.S. Standard Sieve Number 1
12 9 6 ! 2 11/2 I 3/4 1/2 5/8 4 10 20 40
I \ ~'" ['\ ~ ~ ~"' ~ ""'v
~'""' ~ ~ ~~
""""'""' ~ V" "'" L"" ~ "~ ~""'~ ~'-" r\ ~ 0 ~~
"""""'""'""" \ ~ ,, ~ ""~ ~ ""''\: \~ [\ ~"' ~"' ~ ""'""'"' ~ ~ t< ~~
""""'""' ~ ~ ~ ~ ~""' ~ ' 0 ~~ ~""' ""'~ ~ '~ ~ ""'~ '~""" ~~y
~ ""'~""' ~ ~"\:'
~
~
eoo 100
BOU..DERS COBBLES GRAVEL
Coarse Fine
~.
TOTAL NUMBER OF SAMPLES: 35
' ~ ~ ~ ~""' ~ '['. "'~ ~ ' ~'-""-'\ ~ ~"' ~""' y " ~ ~ ' "" ['.,""" ;::
""""
~~ '""'""' '\
"~ '\ ~ ~
f'..""-~ ~ ~ ~""' ~ " " ~ '"" ~'\:
['., ·"' "' """"
~~
"""""' ""'"""
~'-" ['\., ~
"""
,y ,, [\: ~"""' ~ ""~ " """' ~ ~ """~ "" \, ~ ~'\ ~~ " ["\.,"-~ t\ .~
' ~ l\ """~ ~~~ 1'-~ ' ~ r0 ~'\
""' ""'
~ K' ~"' ~""'""'"' " ' ~ ~ """~ ~'""-""' ·"' ~~
""'""'""' '\
f"-'\,_ \: ["'; ~' f'.."-" ·"' ~ ,"\:' ~""'~ I'' ['.,"' ~
'"""
~~
"""' ~ ~ ~'\ ~""'""'"' 1"-"' ~ ~ ~~
" "'" ~ ""''\: ~ ""''\ "'' """
1\..' ~'\
"""" ['\ "'" ~""' ~ ""'""' "\.,
'"'-" r0 ~ ""'"\:'
"~ ~ 0 ~~ """"' ~ '\
"['., ' [\_ ~ ~~
'I"'-[\, ~ ~' ~""' ~ 1'-" ~ ~ ~'\:
~ ~ ~'\
I"""'""'""" "'""' ~ ~ ~"' ~ ~~ "'~ ~ 0 ~'\:
1-~t.::::,. ~ ~ ,y
~
e o.e
SAND
Medium Fine
WATANA
BORROW SITES I 8 J
RANGE OF GRADATIONS
1 ) .... -) . -1 .. -1 ... -1 -J
Hydrometer
eo 100 200 210
I I I' 0
10
~
~""\ 20
~""' ""\ ~ ""'"\ ~""'""'" ~""''\ ~""' ~
""'""'""' '\
~
~""' ~ "~~
~""'""'""' "I" I'\
~ ""'~ ['.,"-., ~
~~ '-f"-1""-~ t\
30 -&! ao •• 40 ~
~
.A ...
!50 Ill .. .....
0
0
0
60 c
I)
u ... ..
70 Q.
~ ""'~ ""' ' ~ ~ [\.
~""' ~ "' ~ ~ ~ "~ 80
""'""'""' '\
f'.."-' '\ ~ ~"' ~
~""'~ ""' ,; ,'\ ~~
1'-""'""' '\ .... ~" 90
~""""" I','-~ ~ ~ "'~ ~""' ~ "['., " ....
"' ' "' ~
0 .QO!S Ql o.oe 0.01 QOOIIOO
FINES
Silt Sizes
FIGURE 6.54
l ----1 1 ---J l --1 l -l --1 -------1 --1 1
~~----~----------------~
I
I
I
I
I
I
I
.....
<P c
lL
U.S. S1ondard Sl'"e Openinvs In Inches
100 -IZ 9 6
I I
90
80
70
60
50
100
BOU...DERS COBBLES
U.S. Standard Sieve Numbert
3 2 11/2 I 3/4 1/2 3/8 4 10 20 40 80100
I
00 10
GRAVEL
Coarse Fine
MATERIAL
SILTY SAND
SAND
GRAVEL
SAND
Medium Fine
NO. OF SAMPLES
6
4
25
WATANA
BORROW SITES I 8 J
STRATIGRAPHIC UNIT GRADATIONS
Hydrometer
200 2:70
II
FINES
Silt Sizes
FIGURE 6.55
0
10
20
30
40
50
60
70
80
90
0001 100
-.c
01 •• 3t
>.
..0 ...
t)
"' ... c
0
(.) -<:
Q)
<..> ...
Q) a..
1700
1650
,_
w w
"-
z
0
i= 1550 .. > w
...J w
1500
1450
17 00
1650
;:: 1600 w w
"-
z
0 1550
~ > w
...J w 1500
1450
1850
1800
1750
1700
,_
w
~ 1650
z
~ ,_
;; 1600
w
...J w
1550
1500
1450
SUSITNA
RIVER
o•.--AZIMUTH --..laO•
OF SECTION /
/7
2 .. /··
,r"-/ ~ ··~ . 7 _/-.. /··
·0<' ~--·:.~ II .1"'-:c.:-::--... ---~.. ...--
/ --"::::=.::.. .. · '
EL.I473.0
;' ~ .. I' I L LIMIT OF EXCAVATION r I ' EL 1480 o !ASSUMED) ~--F~~----------------------------------------1~---------------~-----------------------
SUSITNA
RIVER
SECTION B-B
o•--AZIMUTH --+-lao• OF SECTION '~/ ;::::::.~ ------~-~-----~ ~ ~-~-·
.. -~--~~~~~;;.:::::::::,:::::::::-I ~~---I
.?/ / !'
fl IT / I ;' [LIMIT OF EXCAVATION ~ / EL.14800 (ASSUMED)
~'-'-"-"'C--+ L _________ _j ________________________________ i ________________________________ _
SUSITNA
RIVER
SEC TION D-D
o•--AZIMUTH ---lao•
OF SECTION
2
lr::::::::::: .. -:::--
-~··· ~-~~:::/' ~;;rf~
~-:·::?' ' ;;/ I 0 ~-' 0:.-I /( '
fi· I -~ E .
::Y I
// I '
1650
1600
1550
1500
1450
... f;. ,1 SUSITNA RIVER
(/ I [L IM IT OF EXCAVATION
{ EL .I480.0 (ASSUMED)
~--+'~-----------; _________ ----------------------
SECTION F-F WATANA
PLAN
QUARRY SITE L PLAN AND SECTIONS
REFERENCE • BASE MAP FROM CO E , 1978 I"= 200' WATANA TOPOGRAPHY,
SHEETS 8 S. 9 OF 26 COORDINATES IN FEET , ALASKA STATE PLANE (ZONE 4)
APPROXIMATE QUARRY SITE LIMIT
QUARRY SITE L PHOTO
/
N 3 228 50
LEGEND
CONTACTS:
LIMITS OF USABLE ROCK (ASSUMED)
MATERIAL LIMITS
___ .. _ APPROXIMATE TOP OF ROCK
-.. ·-ASSUMED TOP OF SOUND ROCK
B B t l CROSS-SECTION LO CATION
NOTES
I. SECTION LOCATIONS SHOWN ON PLAN INSERT.
2 . ALL SECTIONS LOOKING UPSTREAM (EAST).
3. V ERTICAL AND HORIZONTAL SCALE EQUAL.
4. SURFACE ELEVATIONS FROM 1'•200' TOPOGRAPHY-
COE, 1978, TRACED AT 25' CONTOUR INTERVAL .
5. ZONES IN DICATE LEVEL OF CONFIDENCE IN ROCK
AVA ILABILITY AND QUALITY FOR QUARRY USE.
ZON E D MAPPED AS DIORITE PORPH YRY,
COMPETENT AND BLOCKY. ZONE I INFERRED AVAILABILITY ON
BASIS OF OUTCROP EXTENT AND GENERAL SITE
GEOLOGY.
6. DEPTH TO ROCK AND WEATH ERED ROCK THICKNESS
E XTRAPOLATED FROM AIR PHOTO INTERPRETATION
AND GENERAL SITE GEOLOGY.
7. MATERIAL LIMITS INFERRED FROM PRELIMINARY MAPPING
AND ARE SUBJECT TO REFINEMENT AND V ERIFICATION
IN DESIGN LEVEL INVESTIGATION .
8. ENTIRE QUARRY SITE LIES WITHIN PROPOSED RESERVOIR
LIM ITS .
9. ROCK IS INFERRED TO EXTEND TO SOUTH OF AREA
LIMITS, BUT QUANTITY AND OV ERBURDEN DEPTHS
AR E UNKNOWN.
10. LOCATION OF SEISMIC LINES ADJACENT TO QUARRY
SITE SHOWN ON FIGURE 5 .1 b.
SCAL E
0~~~5~0iiiiiiiiiiiiiiiii'iil00 FEET
FIGURE 6 .56
r-
1
-
-I
-
7 -RESULTS OF GEOTECHNICAL INVESTIGATION -DEVIL CANYON
7.1 -Devil Canyon Damsite
This section discusses the results of a geological and geotechnical in-
vestigation performed at the Devil Canyon site. This section is pre-
sented in two subsections: 7.1 -Devil Canyon Damsite and 7.2 -Borrow
and Quarry Sources and Materia 1 s. Location of maps presented in this
section are shown on Index Map Figure 7.1.
(a) Overburden Conditions
(i) . General
( i i )
The proposed Devi 1 Canyon damsi te occupies a narrow deep
gorge on the Susitna River approximately 26 miles down-
stream from the Watana site at river mile 152 (Figure 4.1).
The terrain. is one of a glacially scoured mountain area
with many deeply incised tributaries cutting down through
the steep canyon walls to river level. The overburden
within the region generally consists of less than one foot
of organics over a veneer of glacial outwash and reworked
tills, mixed with talus on the steeper slopes. Glacially
scoured bedrock knobs and ridges form a fairly pronounced
topography with a grain paralleling the river. A map show-
ing the inferred top-of-bedrock elevations and existing
surface topography is shown in Figure 7.2.
Geologic profiles at the damsite and borrow sites is pre-
sented in Section 7.1 (b). Much of the interpretation used
in preparation of these maps and figures have been based on
seismic velocities of various soil and rock types. Results
of the seismic refraction surveys performed for this study
are presented in Appendices H and I, while surveys per-
formed in previous studies are contained in referenced
reports (12,39,57, and 59). For clarity, Table 7.1 pro-
vides a correlation of seismic velocities with soil and
rock types that have been used in this study.
Damsite
The bedrock at Devil Canyon is well exposed along the can-
yon walls from the entrance of the gorge immediately up-
stream from the· proposed dams i te to Portage Creek down-
stream. On the upper abutments, overburden consists pri-
marily of weathered rock and talus mixed with shallow out-
wash and reworked ti 11 s averaging approximately 10 feet
thick (28).
7-1
On t:ne 50° tO 90° s1 opes 1 h the gorge, overburden ranges
from zero up to perhaps 30 feet thick. Overburden in these
areas consist of scattered debris on rock ledges and talus
slbpes. These talus slopes, which extend into the river,
are generally confined to g~llies Within the gorge walls.
Although the high river flows (up to 35 fps) prohibited
sampling, it is assumed that the channel alluvium consists
bf unstratified talus blocks and boulders n1ixed within a
matrix of smaller rock fragments, gravels, and sand. Total
depth-to-bedrock in the channel beneath the proposed dam-
site and cofferdams is estimated to be approximately 60
feet, of which 20 ·to 30 feet is water and 30 feet. river
alluvium. The maximum depth of river alluvium was calcu-
lated based on USBR drill holes DH-12, DH-13, DH-14, and
the 1~81 Borehole 5a, which crossed beneath the river
(Table 5.2).
Portal structures for diversion tunnels and intakes will be
placed in areas of shallow overburden.
Upstream from the damsite, beneath Borrow Site G, bedrock
appears to drop-off sharply with overburden reaching depths
up to 300 feet. This area is discussed in a subsequent
sect ibn.
(iii) Sur.nu::e Structure Sites
Proposed surface structures on the north abutment are ex-
petted to encounter the same genera1 soil conditions as at
the damsite; With overburden averaging about 10 feet or
less, ana comprising mostly talus with isolated outwash
materials~ Any structures on the south abutment would en-
countef' similar conditions as those which exist at the
saddle damsite (Section 7.l[a][v]).
( i v) trnetgenc¥ Spi 11 way
The proposed emergency spillway 1 ies to the south of the
damsite 011 all east-west trending ridge of exposed partially
covered bedrock (Figure 7.2).
Ill general, overburden is expected to be less than 10 feet
thick along the proposed east-west spillway alignment.
However, where the proposed spillway turns northward
(approximately 2,000 feet downstream from the dam center-
11ne).the structure will cross a relict channel, which
contains up to 80 feet of alluvium (Section 7.1[a][v]).
-
-
-
,_
I
\
-I
-
!""'"'
I
(b)
(v) Saddle Dam
The overburden at the surface in the proposed saddle dam
and emergency spillway area (Figure 7.2) consists primarily
of reworked glacial till. The areas of steep topography
have isolated talus deposits and include a number of shal-
low (<10 feet) weathered bedrock zones.
Beneath the lakes, where the proposed saddle dam is sited,
bedrock drops off into a deep, overburden-f·illed trough
(Figure 7.2). Based on seismic and borehole data, the
stratigraphy in the channe 1 appears to comprise approxi-
mately 10 to 20 feet of outwash (sandy, bouldery till),
underlain in the deeper sections by stratified layers of
sqnd and gravel. This underlying material appears more
compact and clean than the overlying surfi cia 1 deposit
(51).
Maximum overburden depth in the channel area, as determined
by borings and seismic refraction lines (Figure 5.2), is 86
feet, with an average of about 40 feet at the saddle dam-
site. It is postulated that this deep bedrock trough rep-
resents a relict channel of the Susitna River (Appendix J).
Drilling in this channel shows the material to be dense and
relatively impervious. The existence of several lakes on
top of this channel (perched at about 75 feet above rock
level) demonstrates the overall impermeable nature of this
material.
(vi) Camp Areas
Although detailed investigations were not conducted at the
proposed campsite area located approximately 7,000 feet
downstream from the dam, reconnaissance mapping suggests
that bedrock is near surface. Where bedrock is not ex-
posed, overburden is expected to be an average of 5 to 10
feet thick, consisting of sandy, bouldery outwash with
localized zones up to 40 feet deep. The only areas around
the damsite expected to have very deep overburden are: (a)
the upper reaches of creeks from Elevation 1500 to 1800,
(b) areas of pond water, and (c) the relict channel (Figure
7.2). Localized clean sand and gravel deposits will pro-
bably be scarce throughout the area.
Lithology
(i) Introduction
The bedrock in the Devil Canyon damsite is exposed along
the canyon walls of Cheechako Creek and the Susitna River
and in scattered outcrops throughout the area (Figure 7.3).
7-3
Bedrock at the site is a CretaceoUs age {Table 4.1) se ...
quence of interbedded argillite ahd ~raY~acke which lies on
the western side of a Tertiary age granodiorite pluton.
The argillite ahd graywacke have beeh intruded by felsic
and mafic dikes of uncertain age. These rotks have tltlt
been assigned formational names, but rather have been given
lithologic names for mapping and correlation purposes.
Rock names are based on the classification of Travis (43).
The lithology and structure of the Devil Canyon site are
shown on a geologic map (Figure 7.3) and geologic sections
DC-1 through DC-7 (Figures 7.4 through 7.10). The geologic
interpretations are based on field mapping, borehole and
seismic refraction data {Section 5). The location~ of the
proposed civil structures are shown on the geologic map and
sections.
Rock exposures in Devil Canyon are nearly continuous along
the canyon wa 11 s; however, above the break in s1 ope at
about Elevation 1400, rock exposures are more 1 imited.
Access in this area is very difficult due because of steep
slopes. Because of this lack of exposures, the extent of
geologic features could not be determined. Future subsur~
face explorations Will be required to verify areas of in-
ferred geology. In general, only structures more than 1
foot wide are shown on the map unless otherwise noted.
Geologic features mapped at the surface were correlated,
where possible, to similar features in the boreholes and on
seismic profiles. These features are shown on the geologic
sections (Figures 7.4 through 7.10). Areas of insufficient
subsurface data required extrapo 1 at ion of. geo 1 ogi c features
to depth based on mapped surface orientations. For simpli-
city, borehole data are limited to features 5 feet or
greater in thickness. For more detailed information, see
Appendices C and E for borehole logs and pressure testing
details, and Appendices Hand I for seismic refraction sur~
veys. The geologic sections have been oriented to make
best use of the available geologic data.
Approximately 1,200 joints were mapped at the site. This
information was used ·in developing the statistical joint
plots shown in Figure 7.13. On the geologic map {Figure
7.3) only representative joints from the two major joint
sets are shown.
Details of the lithology and structure at the Devil Canyon
site are presented in the follo~ing sections.
-
r
r
-
r""'
i
-!
( i i ) Granodiorite
The granodiorite is located primarily to the east and south
of the site (Figure 4.1). The closest occurrence in the
damsite area is approximately 3,500 feet to the southeast,
where the contact with the argi 11 ite and graywacke is ex-
posed in Cheechako Creek. The contact zone extends over an
area up to about 100 feet wide which contains large argil-
1 ite and graywacke blocks intruded by the granodiorite.
Contacts are generally sharp with thin fracture zones on
either side.
The granodiorite is light gray and fine to medium grained.
It contains quartz, biotite, plagioclase and orthoclase
fe 1 dspars. Where exposed, the rock is fresh and hard to
very hard and massive. The granodiorite has been intruded
by both mafic and felsic dikes.
The extent and depth of the pluton beneath the site is not
certain nor is the dip of the contact known. In BH-2, a
quartz diorite and granodiorite intrusive were intersected
from Elevation 663.0 to the end of the borehole at Eleva-
tion 645.7 (Figure 7.5). The fine grained groundmass and
coarser phenocrysts of this granodiorite are similar to a
diorite dike intersected in BH-7. It is uncertain whether
the materia 1 intersected in BH-2 is a dike or part of the
main pluton.
(iii) Argillite and Graywacke
The rock underlying the Devil Canyon site is a slightly
metamor phased sequence of interbedded argi 11 ite and gray-
wacke. The argillite is a med i urn to dark gray, very fine
to fine grained argillaceous rock. The argillite is very
thinly bedded, hard and generally fresh. Petrographic
analyses show that the argillite is composed of subrounded
to elongate grains of primarily quartz and biotite with
minor iron oxides, pyrite, organic material, amphiboles,
and carbonate (53). Some euhedral biotite flakes up to
0.12 mm were observed. Elongated grains are parallel to
the bedding. ·
The graywacke is 1 i ght to medium gray occasionally varying
to a dark reddish gray. The rock consists of fine to medi-
um grained sand-sized grains in a very fine grained argill-
aceous matrix. Beds are often graded. Zones of coarse
grained lithic conglomerate are found locally. Where map-
ped, these zones are less than 100 feet thick. However, in
BH-1, coarse grained material was encountered between bore-
hole depths 331 to 750 feet (Appendix C). Since this hole
was drilled at an angle to bedding, tbe apparent thickness
7-5
is greater than the tru~ thickness bf the u it. Petro-
gfap~1ti ahi:l.lyses show the ~raywacke is sim lar to the
argillite tl.hd composed of quartz; feldspar, and biotite
with mihbr iron oxides, pyrite and. organic material.
PYrite and other sulphides are genera 11y 1 ess than 1 per•
cent; but 1oca11y range up to 5 percent of the rock mass in
both the argillite and graywacke.
the argillite and graywacke interbeds range from less than
1 inch to greater than 10 feet thick, but are generally
1~ss than 6 ihches. FigUre 7.11 is a photograph of the
typi ca 1 i hterbedded argillite ami graywacke found at the
sit e. Contacts between the beds are sharp and tight with
bedding parallel to foliation. The generally weak folia-
t i oh is better de vel oped i 11 the argillite than the gray-
wacke because of the effect of graih size. Foliation, as
described here, refers to the planar structure of the rock
resulting from the parallel alignment of platy and elongate
grains. In most boreholes and in some outcrops, the folia""
tioh has developed a phy11itic sheen in the argillite beds.
Bedding/foliation strikes northeast with dips to the south-
east of generally 50° to 70°• The dip of the bedding/foli-
ation is shown on the geologic map and sections. On the
geologic sections, the apparent dip is indicated where
appropriate.
A minor secondary foliation was found subparallel to the
main foliation.
the argillite and graywacke have been injected with numer-
ous quartt veins and stringers. Stringers are defined as
qUaftt injections 1ess than 0.5 inches thick. Veins ate
qUartz injections greater than o.s inches thick, while
veins are greater than 1 foot Wide. At least two episodes
of injection have been observed. The first episode con-
·sists of quartz veins and stringers parallel and subpar•
a11~1 to the bedding/foliation~. These veins and stringersj
Which 111ay have been injected before or during deformation,
have been stretched, folded, and occasionally offset along
fo1iatioh planes. The contacts of the veins and stringers
with the bedrock are tight and very hard. The veins and
stringers occur either singly or in groups measuring up to
10 feet wide in outcrops and up to 30 feet along the bore-
holes, In these tortes, the amount of quartz is as much as
20 to 40 percent of the whole rock. In general, however,
these zbnes are 1 ess than 1 foot wide. These veins and
stringer~ are good quality rock with high RQDs.
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Th~ second episode of quartz i ntr1,.1s ion is represented by
undeformed, post~deformational quartz veins which cut
across th~ bedding/foliation and the quartz intrt,Jsions of
the first episode. Thes~ veins also contain iron and lead
sulphide mineralization~ These quartz veins are associated
with very closely to closely fractured rock. RQDs are us-
ually slightly lower in these zones than the surrounding
rock~ Most of the veins are less than 2 feet wide.
Although quartz veins and stringers of both episodes are
encountered in all boreholes, they are most numerous in
boreholes BH-1, BH-2 and BH-4. Quartz veins and stringers
associated with the second episode of intrusion are found
in both felsic and mafic dikes.
(iv) Dikes
The argi l1 ite and graywacke at De vi 1 Canyon have been in-
truded by a series of mafic and felsic dikes (Figures 7.3,
7.4, 7,5, and 7.10). The mafic dikes are designated M 1
through M 4, while felsic dikes are designated F 1 through
F 8. Geo 1 ogi c tec::hni ca 1 c 1 imbers were used to map the
location and extent of these features along the canyon
walls from the mouth of the canyon downstream to about the
locations of DH-12 and DH-14 (Figure 7.3}. Th!i! dikes gen-
erally occur in topographic lows or gullies. Some of these
gullies had been misinterpreted by previous investigations
to be shear zones. A survey contra 1 of the 1 ocat ions of
four dikes (M 1, M 2, M 3, arid F 4) in the damsite area was
performed for the purpose of insuring an adequate correla-
tion across the Susitna River. A magnetometer survey, per-
formed on the south bank, was unsuccessful in tracing their
extent beneath the overburden away from the gorge walls.
Four mafic dikes were mapped in the damsite area. Dikes
M 1, M 2 and M 3, are in the area of the powerhouse and the
diversion tunnels, while M 4 is located approximately 2,000
feet downstream from the dam centerline (Figure 7.3).
Strikes of the mafic dikes are approximately northwest-
southeast, crosscutting the bedding/foliation and trending
parallel to Joint Set I (Section 7.1[c]), Dips are verti-
cal to steep to the northeast and southwest. The mafic
dikes are generally dark green to dark gray. fine grained,
fresh to slightly weathered, and hard. They consist pri-
marily of feldspar in a fibrous groundmass with accessory
pyroxime, biotite, hornblem:Je, and calcite. ln BH-1 and
BH-.2 mafic dikes contain from 5 to 10 percent euheoral ~
White~ r~diating zeolites up to 0,2 inches in diameter.
The rni.ific dikes have been classified as diabase. Joint
spacing in the dikes is very close to close with
7-7
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slickensides and chlorite on most surfaces. Because of the
joint spacing, the dikes tend to erode more readily than
the surrounding argillite and graywacke resulting in their
forming talus-filled gullies. Dike widths vary within the
same dike ranging from 2 to 10 feet.
The borders of these dikes are generally finer grained with
11 Chill zones .. usually 0.5 to 1 foot wide. Contact metamor-
phism is evident in the argillite and graywacke adjacent to
the dike. Fractured and shear zones ranging from 1 to 10
feet but generally less than 5 feet wide, are frequently
found immediately adjacent to the contact.
The felsic dikes are light yellowish-gray to gray and
aphanitic to medium grained, but generally fine grained.
They range from rhyolite to granodiorite in composition and
contain quartz phenocrysts. The fe 1 sic d·ikes are generally
iron oxide stained and, at the surface, are slightly to
moderately weathered. At depth, they are fresh and hard.
Because of the very close to closely spaced joints, the
felsic d·ikes tend to erode readily and form talus-filled
gullies. Figure 7.12 is an aerial view of the site showing
the gullies in which the dikes occur.
The contacts are healed, but with secondary localized
shearing or fracturing at or near the contact. Chilled
margins up to 3 feet wide are evident in the larger dikes,
with contact metamorphism in the argillite and graywacke.
The orientation of the majority of felsic dikes is predom-
inantly northwest and north, with vertical to steep dips to
the east and west. These dikes are generally parallel to
Joint Set I (Section 7.1[c]) and cut across the bedding/
foliation. Several small felsic dikes, however, were noted
in the borings to be parallel to the bedding/foliation.
The width of the felsic dikes varies from 2 to 60 feet, but
in the immediate site area is less than 10 feet. The wid-
est dikes are found upstream from BH•5a and from approxi-
mately 2,500 feet downstream from the dam centerline
(Figure 7.3). The widest felsic dike at the site is ex-
posed on the north bank of the river north of Borrow Site G
(Figure 7.3). This dike is up to 60 feet wide but pinches
out to less than 10 feet at either end of the outcrop. The
trend is northwestward with a 75° dip to the northeast.
The dike is light gray but weathers to a yellow-orange
caused by iron oxide staining. Grain size is fine with
fine to medium grained quartz phenocrysts •
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(c) Structure
(i) Introduction
( i i )
This section discusses geologic structures at the Devil
Canyon site and their relation to the proposed dam location
and tunnel routes. The section is divided into two subsec-
tions. The first discusses joints and joint sets while the
second discusses shear and fracture zones.
Joints
The orientation of major and minor joint sets was recorded
at all outcrops, as well as the condition of the joint sur-
faces, spacing, and any mineralization or coating. Four
joint stations {DCJ-1 through DCJ-4) were also selected for
detailed joint measurements (Figure 7.13) in areas consid-
ered to be representative of all joint sets.
One hundred joints were recorded at each of the stations
except DCJ-1 where 93 joints were recorded. For each sta-
tion, joint measurements were plotted on the lower hemis-
phere of a Schmidt equal-area stereonet at 1, 3, 5, 7, 10,
and 15 percent contours (Figure 7.13). The plotting method
is described in Figure 6.12.
In addition to the joint station plots, composite joint
plots were constructed from joint stations and outcrop
data. Composite plots were constructed for the north and
south banks and are shown on Figure 7.13.
Four joint sets were mapped at the Devi 1 Canyon site and
are identified on both composite and joint station plots.
Sets I and I I are major sets which occur throughout the
site area, while Sets III and IV are less prominent but are
locally strong. Table 7.2 is a summary of joint set orien-
tations, dips, spacings, surface conditions, and structural
relations. Each joint set is discussed below.
This discussion is based primarily on surface jointing, as
it was not possible to correlate between joint in outcrop
.and those encountered at depth in the borehole. Joi nt·i ng
in boreholes is discussed in a later section.
Joint Set I is the most prominent set at the site. The
trend is northwest {340°) with vertical to steep dips to
the northeast and southwest. On the south bank, the aver-
age d·i p is vert i tal, whi 1 e on the north bank, the average
dip is 80° to the northeast. Joint spacings vary from 0. 5
inch in fracture zones up to 10 feet, with an average spac-
ing from 1. 5 feet to 2 feet. These joints are planar and
7-9
smooth with occasional iron oxide staining and carbonate
coating. Set I joints are very continuous and range from
tight to open. Open joints are well developed on the south
bank and can be traced horizontally for over 150 feet.
These joints are open up to 8 inches at the surface. Set I
joints are parallel to most of the shears, fracture zones,
and dikes in the site area.
A subsidiary joint set, Ib, to Set I was found locally at
DCJ-4 and possibly at DCJ-1 (Figure 7.13). This set
strikes northwest (320°) and dips 55° to the northeast.
Joint Set II includes joints parallel and subparallel to
the bedding/foliation planes. This set strikes generally
northeastward but ranges from 020° to 100°. The average
trends on the north and south banks are 065° and 075°, res-
pectively. Dips are southeast, averaging 55° on both
banks. Joint spacings are generally 1 to 2 feet. The
Joint surface conditions are variable, from planar to
curved and smooth to rough, as a result of folds and cren-
ulations on the bedding/folation planes. No mineralization
was found on joint surfaces at outcrops; however, in the
boreholes, these joints are often coated with chlorite.
Set I I joints are generally tight but tend to be open on
the north bank near river level owing to stress relief.
Slopes on the north bank are parallel or subparallel to Set
II. In the damsite area, the course of the Susitna River
at the damsite parallels this joint set.
Major and minor shears are associated with Set I I joints
and are discussed in the following section (Shears and
Fracture Zones). A subsidiary joint set, lib, was mapped
at DCJ-1 and DCJ-4. This subset trends north-northeast at
015° with steep (75° to 85°) dips to the southeast.
Joint Set III is a minor set, although locally well devel-
oped. A similar set was described by the USBR (51) in the
vicinity of DCJ-3 on the south bank (Figure 7.13). Set III
is northeast trending with moderate to steep dips to the
northwest. On the north bank, the average strike and dip
are 060° and 80° to the northwest, while on the south bank,
the strike and dip average 025° and 65° northwest. The Set
III joints are planar to irregular and smooth to rough,
with spacings generally 3 feet. Occasional traces of iron
oxide and carbonate are found on the joint surfaces. Both
open and closed joints have been found in Set III. Open
joints are most common on the north bank, particularly
above Elevation 1400 near DCJ-3, where cliffs have formed
parallel to Set III. The continuity of Set III joints
could not be determined.
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Block failures and slumping on the south abutment appear to
be associated with Joint Set III. A large block was mapped
between DH~1 and DH-10 on the south side on a 10-foot deep
northeast trending depression. Other loose blocks related
to this set have been observed to extend at least 25 feet
below the canyon rim. Attempts by the USBR to excavate
rock benches into the abutment to determine the extent of
slumping were inconclusive. However, it is likely to
assume that detached blocks may extend up to 50 feet back
from the gorge walls.
Joint Set IV consists of numerous low angle (dipping less
than 40°) joints. The strongest trend of Set IV joints is
northeast and east, with low angle dips to both the north
and south. The southerly dips are best developed on the
north bank at DCJ-3. A strong northerly dip is evident at
DCJ-1 on the south bank and DCJ-2 and DCJ-4 on the north
bank (Figure 7.13). DCJ-2 shows both dip directions; how-
ever, the northerly dip is the strongest. A secondary low
angle set trends northwestward with dips to the northeast.
This set is best developed at DCJ-1 and DCJ-2.
Locally, the canyon slopes are failing along joint planes
and sliding or slumping towards the river. On the north
bank, most movement is along the Set II (bedding/foliation)
joints which parallel and dip toward the river. Slopes are
generally subparallel to these joints, with slopes general-
ly at 40° to 50° (Figures 7.6 and 7.8). On the south bank,
slopes are steeper (60° to 80°) and are controlled by the
intersection of Sets I, III and IV.
Areas of open joints that could affect engineering design
were identified at the Devil Canyon site. Open joints of
Set I were mapped at several areas on the south bank par-
ticularly east of Borehole DH-1 where four open joints were
traced southeastward up to 150 feet from the edge of the
canyon (Figure 7.3). These joints are up to 6 inches wide
with undetermined depth. Borehole BH-3 (Figure 7.3) was
dri 11 ed northeastward toward the cliff face to intersect
open joints at depth. Zones up to 10 feet wide of open and
jointed rock were encountered along the length of the bore-
hole to a vertical depth of over 100 feet (approximate Ele-
vation 1300).
Drill water was lost at a depth of 122.4 feet along the
hole and never regained. RQDs for BH-3 were low, particu-
larly near the bottom of the hole as it neared the cliff
face (Figure 7.6). Open joints were also encountered in
USBR Boreholes DH-1, DH-8, and DH-9 which were drilled sub-
parallel and across Set I. High water losses and low RQDs
were also encountered in these holes which reflected this
open jointing.
7-11
-Shears and Fracture Zones
This section discusses the shear and fracture zones
mapped at the Devil Canyon site. These features are
shown on the geologic map and geologic sections (Figures
7.4 through 7,10).
-Shears
Shears are structures having breccia, gouge and/or slick~
ensides indicating relative movement. Both healed and
unhealed shears were found at the site. Healed shears
consist of an arg"ill ite and/or graywacke breccia within a.
quartz matrix. These zones may represent syndepositional
deformation that has subsequently been lithified and
hea 1 ed into a hard competent rock. These zones, there-
fore, do not represent a structura 1 weakness or di scon-
tinuity in the rock mass. These features were most evi-
dent in Boreholes BH-1, BH-2, and BH-4. The largest
healed shear was found in BH-4 (Figure 7.6) from 221.0 to
252.0 feet. This zone consists of argillite breccia in a
zone of highly folded and stretched quartz veins which
were intruded by additional quartz veins. Recoveries and
RQDs are high, generally greater than 90 percent, through
these healed shears, with permeabilities on the order of
less than 10-6 em/sec.
The second type of shear found in both surface exposures
and boreho 1 es consists of unhea 1 ed breccia and gouge.
The gouge is light gray to tan clay. Breccia consists of
coarse to fine sand size fragments in a clay and/or silt
matrix. Gouge and breccia are generally soft and fri-
able, and occur in zones normally 0.1 to 1 foot wide.
The thickest gouge and breccia was up to 3 feet in BH-7.
Chlorite/talc and carbonate mineralization are associated
with the shears. Slickensides are common and occur on
the chlorite surfaces. These shears are generally asso-
ciated with fracture zones. Where they are coincident,
they have been denoted as shear /fracture zones.
-Fracture Zones
Fracture zones are areas of very close to closely spaced
(less than 1 foot) jointed rock. Fracture zones are
found in both outcrop and boreholes. As with the shears,
both healed and unhealed fracture zones are common. In
outcrop, both healed and unhealed fracture zones range
from less than 1 foot up to 20 feet wide, but are gener-
ally less than 5 feet. In the boreholes, fracture zones
range from less than 1 foot to 60 feet but are generally
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less than 5 feet as measured along borehole length.
Healed fracture zones consist of irregular and discontin-
uous fractures filled with quartz or carbonate minerali-
zation. These zones are tight with permeabilities con-
sistent with the surrounding rock. Unhealed fracture
zones often have chlorite/talc, carbonate, or quartz on
joint surfaces. Fracture zones tend to form topographic
lows or gullies because of their erodibility. Gullies
formed by some of these zones are shown on an aerial
photograph of the site (Figure 7.12).
Significant Geologic Features
The Devil Canyon site has several significant geologic fea-
tures which include shears, fracture zones, dikes, and open
joints. Dikes and joints have been discussed in previous
sections. The features discussed in this section are: (a)
northeast trending shears in the saddle dam area (GF 1);
(b) a series of northwest trending shears and fracture
zones {GF 2 through GF 11); (c) the bedrock 1 ow beneath
Borrow Site G; and (d) rock conditions beneath the Susitna
River (Figures 7.3).
-Geologic Feature GF 1
GF 1 is located on the south bank approximately 1,000
feet from the Susitna River (Figure 7.3). The shear has
been mapped as passing beneath the proposed saddle dam
nearly parallel to the Susitna River. The shear was
first postulated by USBR (28 and 57) based on several
vertical boreholes (DH-6 and DH-15) which penetrated
sheared and fractured bedrock in this area (Figure 7.3).
The shear was inferred to strike northeastward along a
topograhic depression beneath two ponds and dip northwest
towards the river. Subsequent seismic refraction work by
the COE (39 and 45) in this area indicated a bedrock low
(Figure 5.2) and a low seismic velocity zone in the
bedrock across this feature (Figure 7.10). These low
velocities (10,700 feet per second) occurred from 25 feet
south of DH-4 to 60 feet south of DH-7, whereas veloci-
ties at the north and south ends of the line were about
19,000 feet per second. During this investigation, three
additional seismic lines (SL 80-12, -13 and -15) were run
and two boreholes (BH-4 and BH-7) drilled to define the
nature and extent of this shear zone (Appendix B and H).
The seismic data confirmed the existence of a bedrock low
in this region with the top of bedrock being as deep as
Elevation 1250 (Appendix H). A low seismic bedrock
velocity (12,380 feet per second) was interpreted along
SL ·so-13 beneath the pond. Bedrock velocities to the
7-13
north and south of this anomally were on the order of
16,800 and 18,800 fps, respectively. BH-4 and BH-7 were
angle drilled southward and northward, respectively, to
intersect this postulated shear. No shearing was en-
countered in BH-4; however, BH-7 intersected a highly
sheared and fractured argillite and graywacke from a hole
depth of 87.0 to 130.7 feet. Zones of breccia and gouge
up to 3 feet wide were encountered within a 40-foot wide
fracture zone. Rock fragments were coated with chlorite
and slickensides. Core recoveries were low and RQDs were
0 percent {Figure 7.6). Permeabilities in this zone were
generally 1o-4 em/sec. Based on this borehole data,
the dip of the shear is inferred to be para 11 e 1 or sub-
parallel to the bedding/foliation at approximately 65° to
the south. It is likely that the shear follows the topo-
graphic 1 ow to the west as shown on Figure 7. 3. The ex-
tent of the shear in an easterly direction is unknown.
Additional work will be required in subsequent phases to
more accurately delineate the extent of this feature.
-Northwest Trending Shears and Fracture Zones
A series of northwest trending shears and fracture zones,
parallel to Joint Set I, were mapped in the damsite area
(Figure 7.3). Many of the shears previously identified
by the USBR were found to be mafic or felsic dikes of
which some have associated shearing at the contact {Sec-
tion 7.l[b][iv]). Figure 7.12 is an aerial view of the
site on which the locations of some of these features are
·j ndi cated. GF 2 is a shear and fracture zone that ranges
from 15 to 18 feet wide as mapped at river level on the
north bank {Figure 7. 3). The zone trends 345° with an
80° northeast dip. Based on the projection of its strike
and dip, GF 2 was correlated with a fracture zone in BH-2
at 601.2 to 621.0 feet {Figure 7.5). This zone consists
of planar, smooth joints and irregular, discontinuous
fractures. Many joints and fractures are coated with
ta 1 c and carbonate. RQDs in the zone range from 75 per-
cent to 90 percent with low permeabilities {less than
1o-5 em/sec). No evidence of GF 2 caul d be found on
the south bank.
GF 3 {Figure 7. 3) parallels GF 2 approximately 100 feet
to the west. As mapped on the north bank, GF 3 is 5 to
10 feet wide and coincides with mafic dike M 2. GF 3 has
been tentatively correlated with a fracture zone in the
upper portion of BH-1 from 80.1 to 108.5 feet. This
shear/fracture zone consists of irregular and discontinu-
ous joints and fractures which are carbonate coated and
iron oxide stained with traces of silt and slickensides.
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RQDs are very low, ranging from 8 to 57 percent with per-
meabilities on the order of 1o-4 to 1o-5 em/sec.
On the north bank, GF 3 has been correlated with a shear/
fracture zone in a narrow gully.
Shear/fracture zone GF 4 occurs about 350 feet downstream
from GF 3 (Figur·e 7.3). This zone contains up to 1.5
feet of clay gouge. This zone may correlate with a bed-
rock dropoff on seismic 1 ine SL 81-22. GF 4 projects
northward across the river into a gully where it appears
to splay. This splayed zone may correlate with a small
shear/fracture zone near the bottom of BH-1 from borehole
depths of 678.9 to 683.8. This zone consists of planar,
smooth joints with irregular and discontinuous fractures.
RQDs are low (25 percent and 60 percent); however, per-
meabi 1 ity measurements are 10-6 em/sec i ndi cati ng the
general tightness of the zone.
Shear/fracture zone GF 5 is a small, apparently discon-
tinuous zone located on the north bank near DH-13 (Figure
7.3). The zone occurs in a narrow gully with very close
to close spaced northwest-trending joints. GF 5 was also
intersected in DH-13 at a borehole depth of 93.3 feet
where it is partially healed with carbonate, and quartz
RQDs in this zone are 0 percent.
Shear/fracture zone GF 6 was mapped in a deep gully on
the south bank of the river (Figure 7 .12). The zone
trends northwest, dipping 75° to the west. GF 6 consists
of a 2-to-3 foot-wide fracture zone with 3 to 4 inches of
light gray to black clay gouge. This zone ~1as inter-
sected by DH-10 between 101.1 and 117.8 feet. No gouge
was recovered; however, the joints have occasional slick-
ensides and are chlorite coated. Minor carbonate and
iron oxide is also present in the zone. RQDs are gener-
ally zero throughout the zone. No pressure testing was
done in the borehole; however, reports by the USBR showed
no severe water loss during drilling. GF 6 has been ten-
tatively projected to the north bank.
Downstream from GF 6, four other northwest trending
shear/fracture zones (GF 7, 8, 9, and 10) had been pre-
viously mapped by the USBR. No evidence for these zones
could be found during the 1980-81 mapping program. How-
ever, the mapping in this area was performed during
winter when many areas were covered with snow and ice.
7-15
-Bedrock Low Beneath Borrow Site G
Seismic lines SW-15 and SW-16 performed by Shannon & Wil-
son (39) for the COE in Borrow Site G s hawed a marked
dropoff in bedrock elevation and seismic velocities along
the east end of the seismic lines (Figures 7.2 and 7.9).
As noted from the figures, the bedrock surface is in-
ferred in this area to drop off more than 200 feet along
a west to east traverse across Borrow Site G. Land
access restriction imposed dur·ing this study prohibited
any further investigation of this area. Possible explan-
ations for this apparent anamalous bedrock dropoff could
be attributed to misinterpretation of the seismic data
wherein the lower velocity material could be either a
highly fractured rock in lieu of till or offset of the
rock surface by faulting. The latter interpretation is
unlikely in that the work performed by Woodward-Clyde
Consultants (60) for this project evaluated lineaments in
this area and concluded that there was no compelling evi-
dence for a fault.
Further exploration will be required in subsequent phases
of the investigation to better define the bedrock condi-
tions in this area.
-Bedrock Conditions Beneath Susitna River
The presence of geologic structures beneath the present
course of the Susitna River was examined by both the USBR
(51) and Acres. A series of angle boreholes were drilled
by the USBR from both the north and south banks at river
level (Figure 5.2).
Several of these boreholes (DH-11, -llA, -11B, -llC, -14
and -14A) "daylighted" into the river requiring them to
be redri 11 ed at a steeper angle. RQDs in most of the
river holes was generally greater than 60 percent with
permeabil it i es 1 ess than 10-4 em/sec. These 1 ow
values are primarily attributed to open joints and frac-
tures in the shallow weathered bedrock zone.
Minor fracture and shear zones were encountered in sever-
al of the boreholes (DH-11 and DH-14 series and BH-5a);
however, these were 1 imited in nature and could not be
correlated between borings. No indication was found from
the investigation to suggest either faulting or fractur-
ing parallel to the course of the river.
7-16
,,
-
-i
'
To support this conclusion, the dikes on both abutments
were surveyed and showed no noticeable offsets across the
river.
(v) Geology Along Proposed Long Tailrace Tunnel
-Introduction
This section discusses the lithology and structure along
the proposed 1 ong tail race tunne 1 for the De vi 1 Canyon
damsite. Reconnaissance mqpping was done along the Sus-
itna River from about 2, 500 feet to 10,000 feet down-
stream from the site. Rock exposures are nearly continu-
ous from the damsite to the bend in the river where the
proposed portal area is located (Figure 7.14). From that
point downstream, outcrops are scattered and poorly ex-
posed.
-Lithology
As in the area of the main dam, the lithology along the
proposed ta i1 race consists of interbedded argillite and
graywacke which have been intruded by mafic and felsic
dikes. The argillite is medium to dark gray, very fine
to fine grained argillaceous rock with occasional grains
of fine to medium sand. The graywacke is light to medium
gray and consists of fine to medium grain-size grains in
a very fine grained argillaceous matrix. The interbeds
of argillite and graywacke are generally 6 inches thick.
Contacts between beds are sharp and tight.
Bedding is parallel to a weakly developed foliation.
Bedding/foliation strikes generally northeast with moder-
ate dips to the southeast (Figure 7.14). This secondary
foliation (which is poorly developed at the damsite) is
locally well developed near the proposed tunnel portal.
The secondary foliation strikes nearly north-south with
high angle dips to the northwest. The argi 11 ite and
graywacke have been intruded by numerous quartz veins and
stringers as at the damsite (Section 7.1[b]).
Felsic and mafic dikes were mapped in outcrops along the
river and to the north of the tunnel route. The litho-
logy and structure of these dikes are similar to those
found at the damsite. The felsic dikes consist of two
varieties: rhyolite and granodiorite. The rhyolite dikes
are light yellowish gray to gray. The texture is aphani-
tic to fine grained with fine to medium grained quartz
phenocrysts. The granodiorite dikes are primarily medium
grained plagioclase phenocyrsts in a fine grained ground-
mass of plagioclase, orthoclase, biotite and quartz. The
7-17
felsic dikes are generally slightly to moderately
weathered, medium hard, with very close to closely spaced
joints. Iron oxide staining is common. Widths are gen-
erally 10 to 20 feet. Contacts with argillite and gray-
wacke are generally fractured and/or sheared. Up to 3-
foot-wide contact metamorphic zones are common in the
adjacent argillite and graywacke. The felsic dikes
strike northwest and northeast.
Mafic dikes are generally dark green to dark gray. These
dikes are fresh to slightly weathered and hard. Mafic
dikes are composed of feldspar in a fibrous groundmass
with accessory pyroxene, biotite, hornblende, and cal-
cite. These dikes are generally 2 to 10 feet wide and
trend northwest with high angle to vertical dips. Like
the felsic dikes, the mafic dike contacts are generally
sheared and/or fractured. Joint spacing is very close to
closely spaced.
A nearly 200-foot-wide outcrop of granodiorite was mapped
approximately 4,000 feet north of the river at Elevation
2100. It is not known whether this feature is a large
d·ike or part of the granodiorite pluton surrounding the
site (Section 4).
-Structures
Joint sets and shear /fracture zones simi 1 ar to those
mapped at the damsite are likely to occur along the tail-
race tunnel.
The four joint sets identified at the damsite (Section
7.1[c]) continue downstream; however, variations in ori-
entation and dip occur. Table 7.3 is a list of joint
characteristics for joints along the tailrace tunnel.
Joint Set I is northwest trending with a moderate to high
angle dips to the northeast and southwest. The average
strike and dip of this set in the tailrace area is 325°
and 70° northeast, respectively, which differs slightly
from its average orientation in the damsite of 340° and
80° northeast. Spacings are highly variable but average
about 1.5 feet. The river flows parallel to this set in
the vicinity of the outlet portal.
Joint Set II includes joints parallel and subparallel to
the bedding/foliation planes. This set strikes 065° with
moderate (60°) dips to the southeast. The strike is
essentially the same as at the damsite, although the dip
is slightly steeper.
7-18
-
-
-I
-
.....
''
-i
-
Joint Set III strikes nearly north-south at an average of
022°. Dips are variable from 63° east to 84° west. The
strike of Set III is similar to that found on the south
bank of the dams ite; but about 30° more northerly than
the average strike found on the north bank (Table 7.2).
Dips are generally similar to those at the damsite. Set
III joints are well developed in the vicinity of the out-
1 et porta 1.
Joint Set IV consists of low-angle (dipping less than
40°) joints of various orientations. Those in the vicin-
ity of the tailrace tunnel are similar to those described
in Section 7.1 (c) and Table 7.2.
A 1 though no shears or fracture zones were found during
the reconnaissance mapping downstream from the damsite,
it is anticipated that several such features will be en-
countered along the tunnel. These shears and fracture
zones will likely be less than 10 feet wide and spaced
from 300 to 500 feet apart (Section 7.1[c]).
(d) Rock Quality Designation
The Rock Quality Designation (RQD) for all cored holes drilled by
Acres and the USBR are presented on the Summary Logs in Appendix
C. A tabulation of the RQD values with hole depth is contained in
Tables 7.4 and 7.5.
The overall nature of Devil Canyon rock is that of a very hard,
brittle rock. Little difference is found in rock quality between
the argillite and graywacke. Based on analysis of the RQD values,
the rock is classified as "good" to "excellent."
Overall average RQD for 12 boreholes drilled previously by the
USBR and 7 boreholes by Acres during 1980-81 in the damsite area
is 76 percent (Table 7.4). For the most part, the USBR cores show
slightly lower RQDs than the rock drilled by Acres. This is like-
ly attributed to several factors including poor drilling problems
and core breakage during handling and transport. Similarly, most
of the USBR cores were shallow holes (<150 feet) and reflect lower
RQDs found in near surface weathered and fractured zones. As
noted in Table 7.4, RQD values tend to increase with depth.
The depth of weathering varies from near surface to 80 feet deep
and is mainly evidenced by a high degree of fracturing with joint
staining and minor mineralization.
Lower RQD values were encountered in BH-3 (Table 7.4). This hole
was drilled on the left abutment and inclined northward to inter-
sect a series of open joints along the gorge walls. Other zones
of lower RQDs were found in sheared and highly fractured rock,
i.e., BH-7 (Appendix C).
7-19
In summary, over 70 percent of the rock drilled during the 1980-81
program had RQD values ranging from 75 to 100 percent with only 8
percent having RQDs less than 25 percent. The intact rock at
Devil Canyon has been classified as high strength with an average
modulus ratio and classification of BM (14,16).
(e) Rock Properties
Representative NQ (1.77) core samples of agrillite and graywacke
were selected from BH-1, 2, 3, 5a, 5b, and 7 (Figure 7.15).
Results of the testing program are presented in Tables 7.6 and 7.7
and are discussed below. Representative photos of rock tests are
shown in Figure 7.15.
(i) Unit Weight
Dry unit weights, measured in conjunction with both tensile
and compressive strength tests, gave an average unit weight
of 170 pcf for both the argillite and graywacke.
(ii) Static Elastic Properties
( i i i )
Elastic properties were measured using electronic strain
gages bonded onto the sample in axial and circumferentially
directions. Stress, diametric strain, and volumetric
strain were computed and plotted against axial strain from
which secant modulus, tangent modulus at 50 percent failure
stress, and Poisson's Ratio were determined. Results are
presented in Figure 7 .16. An average of a 11 test results
show:
Static Modulus
Rock T,lpe No. of Tests {x 10 6 psi} Poisson's Ratio
Argillite 7 9.74 0.21
Graywacke 6 10.32 0.19
Combined 13 10.0 0.20
D,lnamic Elastic Properties
Compressional (VP.) and shear (Vs) wave velocities in
fps for both argi 11 ite and graywacke were determined and
dynamic moduli and Poisson's Ratio computed. Results aver-
aged:
Rock Type
Argi 11 ite
Graywacke
Number of Tests
2
2
7-20
Vp (fps)
20,015
19,280
Vs (fps)
11' 520
11' 310
-
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( i v)
An average of all test results show:
Rock Type Number of Tests
Argillite 6
Graywacke 5
Combined 11
Direct Shear Tests
Dynamic
Modulus
( x106 psi)
10.62
11.09
10.8
Dynamic
Poisson's Ratio
0.13
0.22
0.17
The following types of direct shear tests were performed on
both argillite and graywacke:
-natural discontinuity
-polished rock on rock
-polished rock on mortar
Test results are plotted in Figure 7.17. A summary of the
results is as follows:
Argillite ~ Peak ~ Residual c (psi)
-natural discontinuity 27.5° 23° 0
-polished rock on rock,
dry 21.5° 19.5° 0
polished rock on mortar,
dry 31° 25° 0
Graywacke
-natural d i scont i nu ity 25° 23° 0
-natural discontinuity
using inferred co-
hesive intercept 22° 6
-polished rock on rock, 25° 23° 0
dry 21.5° 18° 0
16° 100 0
-polished rock on
rock, wet 20° 15° 0
-polished rock on
mortar, dry 31° 270 90
po 1 i shed rock on mortar,
dry with bond broken
with inferred cohesive
intercept 2JD 6
7-21
Polished rock on rock tests give a material's lowest fric-
tion angle. This angle ignores effects of natural surface
undulations or roughness. Therefore, a "waviness angle" is
applied to obtain a more representative value for design.
This "waviness angle" is based to a large degree on ob-
served field conditions of natural joint surface and site
geo 1 ogy.
For this study, natural surface friction angles were based
on a slick, chloritized, natural discontinuity in argillite
and a smooth, planar, partially open natural joint in gray-
wacke. These discontinuities, which represent unfavorable
conditions, have been considered as lower limit values.
Shear strength of rock against concrete was simulated by
sliding a polished graywacke and argillite core against
mortar. As noted above, these results gave peak ~ values
of 30° and 0 residual between 20° and 26°. It should be
noted that normal rock foundations are rough, giving fric-
tion angles of 35° or higher.
As noted in Figure 7.17, lower friction angles were obtain-
ed under the 150 psi normal load test for rock on mortar
tests. The 150 psi load test is the highest load in a se-
quence of three tests performed on the same sample. There-
fore, it is likely that the previous shear tests performed
on the sample resulted in the surfaces degrading and.
approaching a residual characteristic, thereby giving a
lower result.
Data plots for direct shear tests of polished rock surfaces
show an oscillation of the shear load with displacement of
the rock surface. This indicates that the movement of the
rock surface, relative to each other, was not uniform. The
shear stress reaches a peak after which movement takes
place. The shear stress drops to a residual value but then
builds up to a subsequent peak value. This cycle repeats
itself over the full extent of the displacement range.
The upper and lower bounds of the plotted points are be-
lieved to represent the peak and residual friction angles
for polished surfaces.
Direct shear test data presented here should be considered
only as a preliminary estimate of design parameters. The
final determination of design friction angles will require
a comprehensive knowledge of the geologic structure and
friction angles for each discontinuity as they relate to
each engineered facility.
7-22
-
-
-
-
-
-
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(v) Compressive Strength Testing
Compressive strengths were measured by both unconfined com-
pression and point loading methods.
-Unconfined Compression
Results of unconfined compressive strength tests show:
Number of High Low Mean + Standard
Rock T,lpe Tests (psi} (psi } De vi ati on (psi}
Argillite 21 32,940 8,017 19,792 + 6,533
Graywacke 16 36,570 4,066* 22,755 + 8,600
*Failure along healed joints
Both rock types are variable in strength with higher
strengths reflecting "intact" rock and lower strengths
reflecting cores with inherent weaknesses such as folia-
tion, healed joints, etc. The foliation within the rock
makes the rock slightly anisotropic. Frequency plots
(Figure 7.18) show 90 percent of the combined test
results are greater than 12,000 psi and, assuming a nor-
mal distribution, approximately 70 percent of all tests
fall within the standard deviation, i.e., between 12,925
and 28,235 psi.
-Point Load Testing
Rock strength for BH-1 and BH-2 core was tested at 15-
to 20-foot intervals using a Terremetrics T-500 point
load tester. Statistical data analysis give:
Rock T_lpe Number of Tests
Graywacke 33
Interbedded argil-
lite and graywacke 163
All tests 338
Mean + Standard
De vi ati on (psi)
21,973.:!:. 5,745
21,579 + 6,752
22,393 + 6,842
Frequency plots are presented as Figure 7.19. In compari-
son with the unconfined test, these tests gave slightly
higher values. The probable cause for this is that rock
strength is proportional to the physical dimensions of the
tested sample. For unconfined compression tests, 1 ower
strengths are generally found for the 1 arger diameter sam-
ples (23). Similar effects are also noted in the Watana
test results.
7-23
Both types of tests, however, indicate a high strength
rock. Combining the compressive strength and elastic prop-
erties for both the argillite and graywacke gives a high
strength rock with an average static modulus to compressive
strength ratio (BM)(14).
(vi) Tensile Strength
Rock Type
Argi 11 ite
Graywacke
Number of
Tests (psi)
4
5
High
(psi )
3944
5071
Low
(psi)
3018
1471
Mean + Standard
Deviation (psi)
3410 + 390
2960 + 1515
Argillite test results (Brazilian Split) were relatively
uniform while graywacke results were variable. These tests
show high intact rock tensile strength, which implies high
intact rock shear strengths.
(vii ) Summary
The rock test results presented in this section are consid-
ered adequate for preliminary design purposes. Extensive
geotechnical work including drilling, down hole testing,
geophysics, exploratory adits, laboratory and in situ test-
ing, will be required before the final design parameters
can be determined for each structure. However, tests per-
formed during this, as well as previous studies, show the
rock to be of excellent quality for constructing both sur-
face and subsurface facilities at Devil Canyon.
(f) Rock Permeability
Water pressure tests were carried out in a 11 seven holes drilled
by Acres. Results of the permeability tests are shown graphically
on the summary logs in Appendix C with test results tabulated in
Appendix E. At several locations (BH-4 at depths 90 to 140 feet),
tests could not be completed because of equipment problems.
Water pressure tests performed by the USBR and Acres (Section 5)
confirm that rock permeability at the Devil Canyon damsite is con-
trolled by the degree of jointing, fracturing, and weathering
within the bedrock.
The rock permeability does not vary significantly within the site
area, generally ranging at 1 x 10-4 and 1 x 10-6 em/sec
with lower permeabilities generally at depth and higher permeabil-
ities in the more highly fractured rock zones. A summary of perm-
eability with depth is shown in Figure 7. 20. Permafrost has not
been observed at Devil Canyon and therefore will not affect perme-
ability.
7-24
-
-
-
-
-
' t'
-
.....
,....
t
(g) Groundwater
The damsite is located in a "young" geomorphic terrain which is
characterized by high relief and immature drainage systems. As
stated in Section 7.1 (f), groundwater flows are confined to the
fractures and joints within the bedrock. Based on piezometer
readings and water level readings taken during drilling, it
appears that the groundwater table is a subdued replica of the
surface topography with groundwater gradients steeper near the
river and lakes. Water level readings performed in BH-1 and BH-2
have given relatively constant levels during 1980-81 with depths
of approximately 150 feet and 0 feet beneath the ground surface,
respectively. Other readings taken in BH-4 and BH-7 on the 1 eft
abutment correspond closely with the 1 ake level. Groundwater
levels are expected to be variable throughout the site, controlled
principally by the extent of fracturing within the rock mass.
Some seeps have been noted in the gorge walls indicating ground-
water migration through open joints and fractures. These seeps,
however, are relatively small. No seeps were noted above the
break in s 1 ope.
(h) Permafrost
( i ) General
Climatological data collected during 1980-81 near the site
indicate that the damsite average temperature may be
slightly above freezing, about 1°C. According to published
data, the Devil Canyon site is within a zone of discontinu-
ous permafrost (19). The localized climatic conditions at
the site may, however, be more severe than suggested
because of the high relief and the deep gorge which
receives very little sunlight.
Despite the apparent severe weather conditions, no direct
evidence has been found in or around the damsite to suggest
the presence of significant amounts of permafrost (36).
(i i) Damsite
During drilling and test pitting, special care was taken to
observe any evidence of permafrost, and none was found.
Thermistor strings 250 feet long were installed in BH-1, 2,
and 4 (Figure 7.19) and showed excellent stabilization in
BH-1 and 2 and fair-to-good stabilization in BH-4. The
ground temperatures were a 11 recorded between 1. 7°C and
4. 4°C at depth. BH-1 and BH-2 on the north abutment have
very similar readings, showing the depth of annual ampli-
tude reaching a depth of approximately 50 feet, with nrini-
mum ground temperatures of 1. 7 to 2.1 oc occurring from
7-25
60 to 130 feet below surface topography. Below that depth,
both holes show a consistent warming trend that probably
reflects the natural geothermal gradient. Geothermal grad-
ients appear to be average, showing about 1°C per 300 feet
(1 °F per 166 feet) (24).
(iii) Emergency Spillway
The emergency spillway area is not expected to have any
permafrost in rock, and only sporatic frost in the overbur-
den. In the downstream out 1 et area, where overburden may
reach 75 feet or more, remnant permafrost lenses in the
till may be expected. Annual frost penetration is expected
to be about 10 to 15 feet.
(iv) Saddle Dam
The thermal regime in the saddle dam area is similar to the
damsite, as shown by the thermistor log of BH-4 (Figure
7.21). Based on these data and auger drilling in this
area, no evidence of permafrost was found. Because BH-4
was angled under the lake, the thermistor string extends
only approximately 175 feet below the top of the alluvium.
The apparent 1.5° variation in downhole temperature (4.4°C
in August to a low of 3.1° in December) could reflect
changes in lake temperature through the year as water mig-
rated from the 1 ake through open joints and fractures
around this section of borehole. The apparent subzero tem-
peratures at depth were noted as erratic and inconsistent
when the readings were taken. Therefore, the May 24, 1981
reading at 200 feet has been neglected. Likewise, the
erratic and fluctuating readings on one of the 250-foot-
depth thermistors, with total failure on the latest set of
readings, make this a suspect data point (Figure 7.21).
Additional instrumentation will be required in this area to
further define the subsurface thermal regime.
(v) Camp Areas
Based on auger holes and USBR investigations, permafrost
should be expected to occur in the proposed camp area as
localized small lenses or zones within the overburden.
Annual frost heaving can be expected in the overburden.
(vii) Access Roads
Access and construction roads can be expected to encounter
scattered permafrost lenses and pockets. The annual frost
penetration is likely to cause heaving in much of the allu-
7-26
-
-
-
-I
-
-'
vial material, particularly the clayey moraines and thin
outwash deposits. Groundwater flow, where encountered, may
F-cause seasonal "icing,'' which cou·ld disrupt drainage. Fur-
ther investigations of permafrost and foundation conditions
along the proposed access roads will be required in subse-
·~""" quent studies.
-
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t
7.2 Borrow and Quarry Material
The borrow investigations at Devil Canyon were performed with the use
of auger drilling, test trenching, field mapping, seismic refraction
and air photo interpretation as described in Section 5.
The objectives of the 1980-81 investigation were to:
-define the limits of previously identified borrow sites;
-identify new borrow sites; and
determine material properties and volumes.
The information collected during this investigation has been combined
with data from previous investigations to develop a comprehensive data
base for each borrow and quarry sit e. One borrow site and one quarry
site were identified for this study. Borrow Site G was investigated as
a source for concrete aggregate and Quarry Site K for rockfi 11. Des-
pite detailed reconnaissance mapping around the site, no local source
for impervious or semipervious material could be found. As a result,
Borrow SiteD (Section 6.3) has been delineated as the principal source
for this material. Further investigations may identify a more locally
available source. The following sections provide a detailed discussion
of the borrow and quarry sites for the Devi 1 Canyon development.
(a) Borrow Site G
(i) Proposed Use
Borrow Site G was previously identified by the USBR and in-
vestigated to a 1 imited extent by the COE ( 4 5, 51) as a
primary source for concrete aggregate. Because of its
close proximity to the damsite and apparent large volume of
material, it became a principal area for investigation dur-
ing the 1980-81 program. The scope of the 1980-81 investi-
gation in this borrow site is discussed in Section 5 and
shown in Figure 7.22.
(ii) Location and Geology
Borrow Site G is located approximately 1,000 feet upstream
from the proposed dams it e. The area delineated as Borrow
Site G is a large flat fan or terrace that extends outward
from the south bank of the river for a distance of approxi-
mately 2,000 feet. The site extends for a distance of
7-27
approximately 2,000 feet. The site extends for a distance
of approximately 1,200 feet east-west (Figure 7.22).
Cheechako Creek exits from a gorge and discharges into the
Susitna River at the eastern edge of the borrow sit e. The
fan is generally flat-lying at Elevation 1000, approximate-
ly 80 feet above river level. Higher terrace levels that
form part of the borrow site are found along the southern
edge of the site above Elevation 1100.
Vegetation is scattered brush with mixed deciduous trees
found on the floodplain and fan portions. On the southern
hillside portion of the borrow site, heavy vegetation is
evident with dense trees and underbrush (Figure 7.22). The
ground cover averages up to 0. 5 foot in thickness and is
generally underlain by 1 to a maximum of 6.5 feet of silts
and silty sands. This silt layer averages 1.5 feet thick
on the flat-lying deposits, and up to 2 feet thick on the
hillsides above Elevation 950.
No groundwater was encountered in any of the explorations.
The high permeability of the material provides for rapid
drainage of the water to the river. Annual frost penetra-
tion can be expected to be from 6 to 15 feet. No perma-
frost has been encountered in the area.
The borrow material has been classified into four basic
types, based on the interpretation of field mapping and ex-
plorations. The four types of material or zones, as iden-
tified on the map {Figure 7.22), are: Susitna River allu-
vial gravels and sand (Zone I), ancient terraces (Zone II),
Cheechako Creek alluvium (Zone III), and talus (Zone IV).
The large fan deposits are a combination of rounded allu-
vial fan and river terrace gravels composed of various vol-
canic and metamorphic rocks and some sedimentary rock
pebbles. This material is well-washed alluvial material.
Zone I has been divided into two subzones, the upper (Ia)
being generally a sandy layer about 20 feet thick, under-
lain by a thick sandy gravel (Ib) that has been inferred by
seismic refraction {39) to extend well below river level.
A section on the west sid~ of the fan is shown in Figure
7.22. The ancient terraces (Zone II) are probably similar
in origin to Zone I, but being higher on the banks, they
likely represent a higher river energy environment; hence,
the gradations are expected to be less uniform with more
cobble size material. The material in Zones I and II is
believed to be generally uniform over a wide range and
depth with a trend towards coarser materials with depth.
The Cheechako Creek alluvium (Zone III) is bouldery with
some angular particles.
7-28
-
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The talus (Zone IV) comprises argillite and graywacke
derived from the bluffs immediately above the fan. This is
composed of the same type rock as the damsite.
Reserves
The borrow site quantities were broken down into zones as
shown on the typical sections based on the exploration logs
and test trench sections shown in Appendix G {Figure
7.22).
Based on these data, the quantities of fine sands and
gravels in Zones Ia and lb above river level have been es-
timated to be approximately 1.1 and 1.9 mcy, respectively.
Additional quantities could be obtained by excavating below
river level. The quantity of material in Zone II is tenta-
tively estimated to be approximately 2 mcy. This, however,
has been based on an inferred depth to bedrock. If bedrock
is shallower than estimated, this quantity would be less.
Zone III material is estimated at 1.1 mcy, while Zone IV is
55,000 mcy. Zone IV quantities are too small to warrant
consideration as a borrow material.
An estimate of the total quantity of borrow material is
about 3 mcy with an additional 3 mcy potentially available
from inferred resources. The increase in river level
caused by diversion during construction may affect the
quantity of available material from this site. Therefore,
further work will be required i n subsequent studies to
accurately determine available quantities and methods and
schedules for excavation.
(iv) Engineering Properties
A detailed petrologic description of the material was per-
formed by the USBR (52) and Kachadoorian (29) and, there-
fore, have not been repeated here. In summary, the deposit
is a gravel and sand source composed of rounded granitic
and volcanic gravels, with a few boulders up to 3 feet in
diameter. Deteriorated materials comprise about 8 to 10
percent of the samples.
Testing performed by the USBR (52} indicates that about 2
to 4 percent of the material was considered adverse
material for concrete aggregate.
Results of the 1 aboratory tests performed for the project
are summarized in Table 7.8. A composite grain size curve
showing the wide range of gradations in Borrow Site G is
shown in Figure 7.24. A more detailed breakdown of the
7-29
various stratigraphic unit gradations is shown in Figure
7.25. Units identified in Figure 7.25 correspond with
those units mapped in the test trenches {Appendix G). In
summary, two distinct grain sizes are found in the site:
{1) from the auger holes {Unit D), a fairly uniform, well
sorted coarse sand with low fine content and {2) from the
test trenches {Unit Z), a fairly well-graded gravelly sand
averaging 10 percent passing No. 22 sieve. The principal
reason that the auger drilling did not encounter the
coarser material is likely reflective of the sampling tech-
nique where the auger sampling could not recover the
coarser fractions.
A finer silty layer {Unit C) overlies much of the borrow
site. Samples from the higher elevations are more sandy
than those from the fan area.
Based on observed conditions, the grain sizes from the
trenches are considered more representative of the material
in Borrow Site G at depth, while the finer fraction repre-
sents the near surface material. The specific gravity
testing gave values ranging between 2.33 and 2.87 with
natural water content ranging from a low of 3.7 to a high
of 30.9 percent with an average of around 12 to 15 percent.
Dry and wet density ranges from a 1 ow of 90 through 143 and
95 through 153 pcf, respectively.
(b) Quarry Site K
(i) Proposed Use
Quarry Site K was identified during this study as a source
for rockfill for the construction of the proposed saddle
dam on the left abutment.
{ii) Location and Geology
The proposed quarry site is approximately 5,300 feet south
of the saddle damsite, at approximate Elevation 1900
{Figure 7.26). The site consists of an east-west face of
exposed rock cliffs extending to 200 feet in height. Vege-
tation is limited to tundra and scattered scrub trees.
Drainage in the area is excellent with runoff around the
proposed quarry site being diverted to the north and east
toward Cheechako Creek. The groundwater table is expected
to be low and confined to open fractures and shears.
7-30
-
-
-
-
-
-
-,,
I
-r
-
r-
1
,,
'
.I"""
I
The bedrock is a white-gray to pink-gray, medium grained,
biotite granodiorite similar to that at the Watana damsite
(Section 6). The rock has undergone slight metamorphism
and contains i ncl usi ons of the argi 11 ite country rock with
local gneissic texture. The rock is generally massive and
blocky, as evidenced by large, blocky, talus slopes at the
base of the cliffs.
The rock is probably part of a larger batholith of probable
Tertiary age which has intruded the sedimentary rocks at
the damsite (Section 4).
{iii) Reserves
( i v)
The limits that have been defined for the quarry site
(Figure 7.26) have been based on rock exposure. Additional
material covered by shallow overburden is likely to be
available, if required. However, since the need for rock
fill is expected to be small, no attempt was made to extend
the quarry site to its maximum 1 imits. The primary quarry
site is east of Cheechako Creek (Figure 7.26). This area
was selected primarily because of its close proximity to
the damsite and high cliff faces which is conducive to
rapid quarrying. The 1 ow area west of the site was not
included because of possible poor quality sheared rock. A
secondary (backup) quarry source (Figure 7.26) was deline-
ated west of the primary site. Because of the extensive
exposure of excellent quality rock in this area, additional
exploration was not considered necessary for this study.
The approximate volume of rock determined to be available
in the primary site is about 2.5 mcy per 50 feet of exca-
vated depth, or approximately 7.5 mcy within about a 30-
acre area. The alternative backup site to the west of
Quarry K has been estimated to contain an additional 35 mcy
for 150 feet of depth, covering some 145 acres.
Engineering Properties
The granodiorite was selected over the more locally avail-
able argillite and graywacke because of the uncertainty
about the durability of the argillite and graywacke under
severe climatic conditions.
The properties of the granodiorite are expected to be Slml-
lar to those found at the Watana damsite (Section 6.1[e]).
Freeze-thaw and wet-drying (absorption) tests performed on
.rock types similar to those found on Quarry K by the COE
{49) exhibited freeze-thaw losses of <1 percent at 200
cycles and absorption losses of 0.3 percent. Both tests
showed the rock to be extremely sound and competent.
7-31
-
\-.-
r-
1
-,,
I"""
I
l
-
-!
Feet per
Second (f s)
3000-4000
4000-5000
5000-7000
7000-9000
9000-12000
12000-14000
14000-17000
TABLE 7.1: DEVIL CANYON SEISMIC VELOCITY CORRELATIONS
INFERRED MATERIAL
Shallow sands, gravels, soil -dry surficial including denser
gravels, sand, talus and slopewash, generally well drained.
Dry gravels and gravelly sand could include frozen alluvium and
slopewash if present.
Saturated and/or frozen (if present) material from classifica-
t ions above.
Saturated coarse materials including gravels, outwash, till.
Dense gravels, tills, reworked tills and possible highly
weathered bedrock.
Rock, highly weathered, open fractured and/or sheared.
Rock, weathered, fractured or sheared but not necessarily openly
fractured.
Bedrock, slightly weathered.
17000-19000+ Bedrock, very sound, tight, only slightly weathered.
Reference: 39, 51, 57, and 59.
Joint S t r i k e
Set Location \Range} \Avg.}
I North Bank 320°-0° 345°
lb DCJ-4 320°
South Bank 310°-350° 340°
II North Bank 040°-090° 065°
lib DCJ-4 015°
South Bank 020°-100° 075°
lib DCJ-1 015°
III North Bank 045°-080° 060°
South Bank 015°-045° 025°
IV North Bank Variable
orient at ions
Strongest Concentrations:
Composite 060°
DCJ-2 060°
DCJ-3 090°
DCJ-4 045°
South Bank Variable
orientations
Strongest Concentrations:
Composite
DCJ-1
*Surface joints only
**Where present
J
050°
330°
330°
060°
345°
TABLE 7.2: DEVIL CANYON
D 1 E
\Range) (Avg.)
5 E a c 1
(Range)
60°NE-70°SW 80°NE 0.5"-10'
55°NE
60°NE-75°SW 90° 0.5"-5'
40°-75°5( 55°SE 6"-3'
85°SE
30°-75°SE 55°SE 2"-6'
75°SE 2"-5'
50°NW-70°SE 80°NW 4"-10'
68°-80°NW 65°NW 6"-10'
Shallow to moderate ) 3"-8'
)
)
)
)
15 °SE)
30°NW)
10°5 )
25°NW)
Shallow to moderate )
)
)
)
)
25°NW)
20°NE)
15°SW) 1"-8'
40°NW)
15° NE)
_j
----~ .I J J
JOINT CHARACTERISTICS*
n si*'* S u r f a c e c 0 n d i t i 0 n s
(Avg.) Texture Coating Remarks
1. 5') Planar, smooth, Occasional iron Parallel to shears,
) occasional rough, oxide and carbonate fracture zones and
) cant inuous most dikes. Major
) stress relief, open
2' ) joints on south
) bank. Ib found
) locally
2' ) Planar to curved, None Parallel and sub-
) smooth to rough parallel to bedding/
) foliation. Some
) open to 6" near
) river level. Para!-
1' ) lel to major and
) minor shears. lib
1. 5 I ) is found locally.
3' ) Planar to irregular, Occasion a! iron Occurs locally,
) smooth to rough, oxide and carbonate cliff former roove
) tight to open joints Elevation 1400 on
) the north bank
)
3' ) Locally open joints
2' ) Planar, rough, dis-Occasional iron Probably stress
) cant inuous oxide and carbonate relief, near sur-
) face
)
)
)
)
)
)
)
)
)
)
)
)
)
)
2' )
)
)
-.J -·· .I :. __ J .~J >:.-~---~ .I J ] J I
]
JomE S E r 1 I< e
Set (Range} (Avg. l
I 284°-355° 325°
II 052°-085° 065°
III 006°-038° 022°
IV*** Variable
*Surface joints only
**When present
***See Table 7.2
.. 1
TABLE 7. 3:
D 1 E
(Rangel (Avg.)
50°NE-55°SW 70°NE
37°SE-80°SE 60°SE
63°E-84°W
less than 40°
1 l
DEVIL CANYON TAILRACE TUNNEL -JOINT CHARACTERISTICS*
n a 1 E S E a c 1 n!i!H 5 u r f a c e c 0 1 0 n s
{Rangel (Avg.) Tex£ure Coating Remarks
0.5"-10' 1 o 5 I Planar, smooth, Occasional iron oxide Parallel to shears, fracture
occasional rough, and carbonate zones and most dikes
cant inuous
2"-5' 2' Planar to curved, None Parallel and subparallel to
smooth to rough bedding/foliation. Minor
shears
4"-10' 3' Planar to irregular, Occasional iron oxide Locally well developed
smooth to rough and carbonate
Planar, rough, Occasional iron oxide Probably stress relief, near
discontinuous and carbonate surface
J
J
l
l
J
l
j
]
l
J
l
J
l
_J
l
I
l
_j
J
l
j
_j
-,
'
_j
~orehole*
Ground Surface El. (ft)
Top of Rock El.(ft)
Borehole Dip
Vertical
Depth (ft) RQD
Rock
0'-50' Drilled (ft)
RQOO~
50'-150' "
150'-250' "
250'-350' "
350'-450' "
450'-550' "II
550'-650' "
650'-750' "
Total Hole Length (ft)
Average Hole RQD
*USSR boreholes
""-"' 1415
1404
67°
52.7
66%
107.0
65%
108.8
87%
111. 1
8690
110.0
9mo
107.7
96%
106.6
8990
34.5
85%
738.4
84%
"H-L BH-) ~~;; ~~Do a ~~ii'o 1214 1405
1212 --1346 -- --
60° 32° 60" 45" 45°
60.2 94.3 58.2 72.5 71. B
79~~ 82% 87% 64~~ 63~~
113.4 187.6 113. B 138.7 128.5
72% 76% 98% 7990 82%
116.4 101.7 117.9 143.2
90% 46% 89% 8190
115.1 114. 3 142.2
87% 90% 88%
117.2 84.5 101. 3
94% 95% 8490
116.2
85%
15.0
96%
653.5 383.6 488. 7 597.9 200.3
8590 69% 92% 81% 7590
TABLE 7.4: DEVIL CANYON RQD SUMMARY
~~3~ ~1~~7 ~;;r3 r,;2~* ~2~"' :;;; I IC ~~6 1Z* ~~6 1£8
un-15* ~~2 1>8 ~~;•~a ~~2 1~0' ~~;•~c Total Rock --1419. 7 1448.3 1424 1425 893 896 896 912 903 902 903 Drilled -so• 45" 30° 45" sz• 57" 60° 45" 45" 37" 53° 60° ss• Average RQD
I
66.2 72.5 99.3 72.5 63.1 31.7 50.0 73.1 49.3 73.9 45.4 60.0 62.0 1228.7
61% 67% 69% 77% 63% 679~ 65~~ 79~~ 28~~ 56% 759~ 72% 58% 68%
134.8 42.2 49.2 12.5 57.6 91.5 48. 7 48.6 59.7 53.2 82.1 19.3 1488.4
60% Gmo 88% 10% smo 54% 7190 82% 11% 7390 71% 17% 69%
141. 2 729.2
88% 81%
143.4 626.1
85% 87%
413.0
9190
223.9
9mo
121.6
90%
34.5
85%
148.5 120.7 123.2 I 485.6 114. 7 85.0 98. 7 121.7 109. o, 73.9 98.6 142.1 81.3 4865.4
76% 64% 75% 67% 57% 58% 68% smo 19% i 56% 74% 71% 48% 76%
-
-I
-
-I
-
-!
-!
r
TABLE 7.5: DEVIL CANYON -BOREHOLE ROCK QUALITY DISTRIBUTION
Rock P~RCENTAGE OF CORE N SPECIF C RQD RM GES
Drilled
Borehole ( ft) 0-25~~ zs-sm.; 50-75~.; 75-9m.; 90-95% 95-100%
BH-1 738.4 2 6 14 21 13 44
BH-2 653.5 4 4 13 21 14 44
BH-3 383.6 25 18 13 24 13 6
BH-4 488.7 1 2 4 13 16 64
BH-5A 597.9 6 6 10 27 21 30
BH-58 200.3 9 3 26 36 15 11
BH-7 485.6 11 5 9 30 18 27
DH-1* 114.7 9 23 31 8 8 21
DH-5* 30.7 16 15 22 16 30 1
DH-6* 20.4 91 9 0 0 0 0
DH-8* 148.5 6 10 24 30 8 22
DH-9* 85.0 16 9 13 33 11 18
DH-10* 120.7 17 18 31 24 10 0
DH-11* 31.2 22 14 12 52 0 o·
DH-11A* 28.3 0 0 27 28 28 17
DH-1B* 33.9 14 15 8 30 16 17
DH-11C* 123.2 11 32 30 21 1 5
DH-12* 98.7 5 15 39 20 11 10
DH-12A* 121.7 4 9 10 24 18 35
DH-13* 109.0 71 14 15 0 0 0
DH-13A* 73.9 14 22 37 3 8 16
DH-14A* 98.6 11 9 20 18 20 22
DH-148* 142.1 9 12 24 16 8 31
DH-14C* 81.3 27 15 35 15 5 3
Total Rock
Drilled
(feet) 5009.9
* USBR core was relogged from boxes. Several holes have core missing.
TABLE 7.6: DEVIL CANYON ROCK TEST SUMMARY -MAFIC DIKES AND ARGILLITE
Borehole Sample
Mafic Dike
BH-1 80-43
BH-3 D-3-350.4
Argillite
BH-2 80-65
80-66
80-67
80-6.8
80-69
80-76
80-77
BH-3 D-3-83.9
D-3-89.6
D-3-127.3
BH-4 80-55
80-56
80-60
BH-5a D-5A-231.3
D-SA-269.1
D-SA-271.1
BH-5b D-5B-149.9
D-SB-155.2
D-58-183.4
BH-7 D-7-174.6
D-7-178.1
D-7-319.5
Borehole
Depth ( ft)
294.5
350.4
247.3
273.0
288.7
305.5
343.1
313.1
319.0
83.9
89.6
127.3
268.95
273.5
366.85
231.3
269.1
271.1
149.9
155.2
183.4
174.6
178.1
319.5
Average (Acres)
DH-4 4-46.8 46.8
4-50.0 so.o
4-50.4 50.4
4-51.3 51.3
DH-8 8-89.6 89.6
DH-12 12-44.5 44.5
Average (All Tests)
= Dynamic modulus
Compressive
Strength
(psi)
13,420
9~472
24,400
8,017
28,467
27,635
10,229
14,589
17,487
17' 893
25,213
15,047
16,227
26,840
18,722
16,227
26,840
21,457
32,940
20,484
.:!:_6,935 SD
12,910
15,980
16,660
21,860
19,792
.:!:_6,533 so
*Eo
*ET = Tangent modulus at 50% failure stress
*Es = Secant modulus
*v = Poissons Ratio
so = Standard deviation
Omt
Weight
(pcf)
159.8
165.7
168.5
168.6
168.8
167.9
168.8
169.0
170.4
170.9
169.6
171.7
170.9
170.1
170.0
170.7
168.2
167.8
168.8
169.2
168.7
170.1
170.4
171.6
169.7
lens de
Strength
(psi) Other*
1 o6 ET = 4.4 x psi, v = 0.20
3,350
106 3,018 ET = 11.8 X psi
Eo = 11.3 X 106 psi, v = 0.19
3,944 ET = 12.7 X 10 6 psi, v = 0.19
Eo = 12.7 X 106 psi, v = 0.30
3,329
3,410
.:!:. 390 SD
Eo = 11 • 6 x 1 g6 p~ i, v = o. 01
Es = 9.4 x 10 6 ps1~ v = o.16
E0 = 10.2 x 1 o6 ps~, v = 0.04
Eg = 11. 1 x 10 ps 1, v = 0.17
A sorption = 0.09, Porosity = 0.24,
Es = 9.9 x 10 6 6 psi~ v = 0.22,
Eg = 8.27 x 10 ps1, v = 0.02
A sorption = g.o8! Porosity = 0. 21 '
Es = 8.9 x 10 6 ps1! v = o.3o,
Eg = 9.62 x 10 ps1, v = 0.13
A sorption = 0.04, Porosity = 0.12
-
-
-
-
1110!
-
~
'
-
'"""l
-
"""'i
-
-
-
-
!""""
I
....
1"""
1
r
l -
I""'
I
-
TABLE 7,7: DEVIL CANYON ROCK TEST SUMMARY-GRAYWACKE
Borehole · Sample
BH-1
BH-2
BH-4
80-42
80-44
80-45
80-48
80-73
80-52
80-53
80-47
80-50
80-62
80-63
80-71
0-3-276.0
80-54
80-59
80-78
Borehole
Depth (ft)
281.8
440.5
449.5
510.65
429.2
571.0
581.2
505.5
536.3
186.4
195.5
445.2
276.0
252.5
351.3
378.05
Compressive
Strength
(psi)
14,589
28,463
28,467
23,453
27' 726
14,556
4,066
14,655
13,420
28,398
29,114
21,960
18,908
Unit
Weight
(pcf)
160.4
168.8
169.8
168.6
167.8
168.1
167.8
165.7
168.1
169.2
180.4
169.6
170,1
169.3
Average (Acres) 20,598 168.8
DH-12A 12A-80.1 80.1
12A-123.8 123.8
12A-143.9 143.9
Average (All Tests)
!;_7' 925 so
28,450
31,280
36,570
22,755
!;_8,600
*Eo = Dynamic modulus
*ET = Tangent modulus at 50% of failure stress
*Es :: Secant modulus
*v :: Poissons ratio
SD :: Standard deviation
173.5
173.5
171.6
169.5
Tensile
Strength
(psi)
1 ,471
2,547
5,071
2j761+
2,960
!;_1,515 so
Other*
ET :: 11.6 X 1 o6 psi, v :: 0.22
106 psi 1 v 0.22 Eo :: 11.3 X ::
Eo :: 11.7 X 1 o6 psi, v :: 0.26
ET = 9. 7 X 1 06 psi' v :: o. 19
ET = 10.9 X 106 psi, v :: 0.23
Es = 9.2 x 10 6 6 psi~ v:: 0.16,
E0 = 8.98 x 10 ps1, v = 0.15,
Af:lsorption = 0~08,. Porosity :: 0.24
~ = 10.2 x 10 6ps1! v :: 0.18,
E0 = 12.09 x 10 ps1, v :: 0.21,
Absorption= o612,.Porosity = 0.33
E8 = 10.3 x 106 ps~, v = 0.16,
E0 = 11.4 x 10 ps1, v = 0.25,
Absorption= 0.07, Porosity = 0.21
TABLE 7.8: MATERIAL PROPERTIES -BORROW SITE G
Hole/ Lab. Mechanical Atterberg
Trench Sample De~th Classi-Analys · s Lin its Specific
Number Number From To ficat ion Gravel ::.and Fine LL t'l Gravity W"' ,.
TTG-1 2 5.0 -SP 65 34 1 2.73
3 16.0 -SP 84 15 1 2.76 ' _j
4 25.5 -sw 77 20 3 2. 72
5 37.0 -SP 55 43 2 2.76
TTG-2 1 2.5 -ML 0 85 15 2.82
2 6.0 -SP 1 98 1 2.78
3 6.5 -GP 62 36 2 2.87
4 8.0 -GP 84 14 2 2.86
5 15.0 -GP 88 11 1 2.87
8 18.0 -t;p 80 19 1 2.79
9 24.5 -GP 79 20 1 2.33
AHG-9 4-8 3.0 1 D. 5 SW-SM 18 71 11 2.54
14 45.0 46.5 SW 66 32 2 2.53 3.7
15 50.0 51.5 SM 0 96 4 2.79 6.8
AHG-10 3-5 1. 5 6.0 SM 0 64 36 2.63
4 3.0 4.5 30.9
5 4.5 6.0 15.7
6-8 6.0 9.0 sw 0 91 9 2.64
6 6.0 7.5 I 11.7
7 7.5 8.5 22.9
AHG-11 6-7 6.5 9.5 SW-SM 17 65 18
6 6.5 8.0 16.3
7 8.0 9.5 14.7
8-11 15.0 31.0 SM 34 52 14
8 14.0 16.5 11.2
AHG-12 5-6 4.0 6.0 sw 34 62 2
7-9 6.0 9.5 SW-SM 53 39 8
7 6.0 7.5 6.8
8 7.5 8.5 7.1
AHG-13 4-7 3.5 9.5 SW-SM 7 82 11
7 8.0 9.5 25.5
4 3.5 5.0 24.7
5 5.0 6.5 18.0
6 6.5 8.0 20.2
8 15.0 16.5 ML 0 24 76
9 20.0 21.5 SM 40 35 25
10,12 25.0 32.0 SW-SM 33 56 11
AHG-14 8,9 6.0 9.0 SM 22 64 14
9 7.5 9.0 9.2 1{) 9.0 10.5 SW-SM 20 72 8 9.9
11 15.0 16.0 SW-SM 41 52 7 -12 20.0 21.5 SW-SM 25 68 7 7.0
13 25.0 26.5 CL 4 13 83 49 16 23.5
-
-
-
-
N 3.218.000
N 5,226,000
N ¥28.000
N U30.000
N 3,232.000
REFERENCE• BASE MAP FROM RaM, 19BI -1"•200'
DEVIL CANYON TOPOGRAPHY.
COORDINATES IN FEET, ALASKA STATE PLANE (ZONE 4)
DEVIL CAN
INDEX MAP.
SCALE 0~~~·;..-;;;lS MILES
LOCATION
0 c ___ ::>
INDEX
BLOCK
NO.
CD
®
@
®
LEGEND
~
*
NOTES
AREA COVERED *SCALE
EXPLORATION 1••eoo'
DAMSITE• TOP OF BEDROCK l"•!iOO'
GEOLOGIC MAP l"•!iOO'
TAILRACE AREA 1"•1000'
BORROW SITE G l"•!iOO'
QUARRY SITE K 1"•1000'
BORROW /QUARRY SITE LIMITS
SCALE AFTER REDUCTION
FIGURE
REFERENCE
FIGURE ~2
FIGURE 7.2
FIGURE 7.3
FIGURE 7.14
FIGURE t22
FIGURE 7.26
1. TOPOGRAPHY AND DETAILS SHOWN ON INDIVIDUAL
FIGURES.
0 1000 2000 FEET
SCALE
FIGURE 7.1
N3,221,000
/
TERRACE
DEPOSITS
/
(
I
\
) (
/ )
/
981 -1"•200 ' RE FER ENCE, BASE MAP FROM R 8 M, I
_,
DEVIL CANYON NT~~TGRAA0.~!·A STATE PLANE (ZO NE 4) COO RDINATES I •
I
I
I
I
/
//TILL
_,/
------/~---
)
I/ I -------1 /
I / /
DEVIL CANYON
/ TOP OF BEDROCK
/---AND SUR FICIAL GEOLOGIC MAP
-------~--
------------":!~
----~
LEGEND
LITHOLOGY '
r-1 OVERBURDEN , AREAS OF TILL' OUTWAS H.
l.___j TERRACE DEPOSITS AND TALUS AS SHOWN .
D ARGI LLITE AND GRAYWACKE OUTWASH
CONTACTS '
LIMIT OF OUTCROP
CONTOUR LINES •
TOP OF BEDROCK, CONTOUR INTERVAL 100 FEET,
---~O FOOT CONTOURS DASHED
---TOP OF BEDROCK, CONTOUR INTER VA L 20 FEET
TOPOGRAPH~ CONTOUR INTERVAL ~0 FEET
O 200 400 FE ET SCALE~~~~--
FIGURE 7.2
i w
I
Nll,221,000-
N3,222,000-
N3,22li,OOO-
REFERENCE • BASE MAP FROM R S M, 1981 -I'• 200'
DEV I L CANYON TOPOGRAPHY.
COORDINATES IN FEET, ALASKA STATE PLANE (ZON E 4)
0
8 ,.:
<z;
"'
8
i w
SCALE
LEGEND
LITHOLOGY:
OVERBURDEN, UNDIFFERENTIATED
ARGILLI TE AND GRAYWACKE OUTCROP
FELSIC DIKE, WIDTH SHOWN WHERE GREATER
THAN 10 FEET
MAFIC DIKE , WIDTH SHOWN WHERE GREATER
THAN 10 FEET
CONTACTS:
-----LIMIT OF OUTCROP
STRUCTUR E :
!:1r'.'! SHEAR, WIDTH SHOWN WHERE GREATER TH AN
LJiik M.I 10 FEET , VERTICAL UNLESS DIP SHOWN
OTH ER :
DC-I
t.t
Ml
Fl
SHEAR , WIDTH LESS THAN 10 FEET, INCLINED,
VERTICAL , EXTENT WHERE KNOWN
FRACTURE ZONE, WIDTH SHOWN WHERE
GREATER THAN 10 FEET, VE RT ICAL UNLESS
DIP SHOWN
JOINTS, INCLI NED, OPEN INCLINED, V ERTICAL
I SETS I AN D II ONLY)
BEDDING/FOLIATION, INCLINED , VERTICAL
GEOLOGIC SECTION LOCATION
JOINT STATION
GEOLOGIC FEATURE DESCRIBED IN SECTION 7.1
MAFIC DI KE DES CRIBED IN SECTION 7.1
FELSIC DIKE DESCRIBED IN SECTION 7.1
I. GEOLOGIC SECTIONS SHOWN ON FIGURES
7.4 THROUGH 7.10.
2. JOINT PLOTS SHOWN ON FIGURE 7.13
3. ADDITIONAL GEOLOGIC DATA FROM USBR, 1960.
4 . CONTOU R INTERVAL 50 FEET.
5. EXPLORATION LOGS AND SEISMIC LINE SECTIONS
IN APPENDI CES C, E, H, AND I.
6. EXTENT OF SHEARS, FRACTURE ZONES AND
ALTERATION ZONES ARE INFERRED BASED ON
GEOLOGIC MAPPING AN D SUBSURFACE
EXPLORATIONS, AND ARE SUBJECT TO
VERIFICATI ON THROUG H FUTURE DETAILED
INVESTIGATIONS.
0~~~20~0iliiiiiiiii4;i;j00 FEET
FIGURE 7.3
11500
~ 1000 ~
..J
"'
1500
SUSITN A RIVER
(LOOKING UPSTREAM)
SW-15A
PR OJECTED ~·f
AZIMUTH o
088"-0F SECTION__. 268
LOOKING SOUTH
BORROW SITE G
(ALLUVIAL FAN)
1,250 FPS
11,150 FPS
Dc-s A H
G-3
PROJECTED
90'S
DEVIL CANYON
GEOLOG IC SECTION DC-I
SHEET I OF 2
SUSI TNA RIVER
(RIVER FLOW-)
CREST OF
UPSTREAM COFFERDAM
EL. 945'
-·.. . . ···::·:-· ... -........ _..::.~.:.:.....:.:.·:.:_::::.·~---....:
APPAREN T-~
DIP
1500
1000
500
LEGEND
LITHOLOGY:
~ ~
D
~
OVERBURDEN, UNDIFFERENTIATED
ARGILLITE AND GRAYWACKE
INFERRED ORIENTATION OF BEDDING/
FOLIATION, APPARENT DIP WHERE NOT EO
FELSIC DIKE, WIDTH SHOWN WHERE
GREATER THAN 10 FEET
r"l MAFIC DIKE, WIDTH SHOWN WHERE
l-,_-.J GREATER THAN 10 FEET
CONTACTS:
APPROXIMATE TOP OF ROCK
LITHOLOGIC, DASHED WHERE INFERRED
STRUCT URE :
r-·-o SHEAR, WIDTH SHOWN WHERE GREATER L . _j THAN 10 FEE T c::J ~~:~J~tfET~f~~O 11m SHOWN WHER E
GEOPHYSICA L SURVEYS :
So sw-15 INTERSECTION WITH SEISMI C REFRACTION
I L IN E
SW ·15 1978, SHANNON a WILSON
SL 80-13 1980, WOODWARD -CLYDE CONSULTANTS
SL81-22 1981, WOODWARD-CLYDE CONSULTANTS
SEISMIC VELOCITY CHANGE
~~~ SEISMIC VELOCITY IN FEET PER SECOND
BOREHOLES :
DH ·1
BH ·1
AH ·GI
8H-I
LITHOLOGYi' F• FRACTURE
ZONE
S• SHEAR
USSR DIAMOND CORE BORI NG
AAI DIAMOND CORE BORING
AA I AUGER H OLE
OTH ER :
DC·I ~
@
Ml
Fl
NOTES
INTERSECTION WITH GEO LOGI C
SECTION DC -I
GEOLOGIC FEATURE DESCRIBED IN
SECTION 7.1.
MAFIC DIKE DESCRIBED IN SECTION 7.1.
FELSIC DIKE DESCRIBED IN SECTION 7.1.
SECTION LOCATION SHOWN ON FIGURE 7. 3.
2 . VERTICAL a HORIZON TAL SCALES EQUAL.
3. SURFACE PROFILE FROM I" • 200'
TOPOGRA.PHY, RaM,I981.
4. EXPLORATIO N LOGS AND SEISMIC LINE SECTIONS
SHOWN IN APPENDICIES C,E, H AND I.
5 . EXTENT OF SHEARS, FRACTUR E ZONES, AN D
ALTERATION ZONES ARE IN FERR ED BASED ON
GEOLOGIC MA PPING AND SUBSURFACE
EXPLORATIDNS,AND ARE SUBJECT TO VERIFICATION
THROUGH FUTURE DETAILED INVESTIGATIONS.
SCALE O~~~~IO!j;O~iiiiii~200 FEE T
FIGURE 7.4
;:
t:J
~
z
0
1500
~ 1000
"' ....
"'
500
TREND
35~.
@--/]
I
PROJECTED
115' AT 17~•
CREST OF DAM
EL.I463'
CREST OF
DOWNSTREAM COFFEDAM ~
SUSITNA RIVER
088.__._ AZIMUTH _____..268 •
OF SECT I ON
LOOKING SOUTH
RIVER FLON--..
-t. RQO
100 !50 0
L___.L__j El..
-892
..-}CORE MIS SING
~-766
DH ·IIC
DH·IIC -,-
\
BOTTOM \
PROJECT ED
eo's
\
\TREN D 335•
WATER DEPTH
UNCERTAIN
I = I!
@ I
INFERRE D SHEAR-I :
TREND 3 40° I
I ~
~ ~APPARENT
DIP
@
INFERRED -i SHEAR
TREND 20•
I )-M4
, r-TREND 3~·
DEVIL CANYON
GEOLOGIC SECTION DC-I
SHEET 20F 2
1500
1000
500
LEGEND
LITHOLOGY:
OVERBURDEN ,UNDIFFERENTIATED
ARGIL LITE AND GRAYWACKE
INFERRED ORIENTATION OF BEDDING /
FOLIATION, APPARENT DIP WHERE NOTED
c.~.'.·---~-~.:,'?'1 .. ·-.' ... :.v, FELSIC DIKE , WIDTH SHOWN WH ERE ~-~ GREATER THAN 10 FEET
,r-••-:, MAFIC DIKE, WIDTH SHOWN WHERE L .• __i' GREATER THAN 10 FEET
CONTACTS:
APPROX IMATE TOP OF ROCK
---LITHOLOGIC , DASHE D WHERE INFERRED
STRUCTURE :
c:~ ~~~~\~~~~~~TSHOWN WHERE GREATER
c := ~mJ~~ET~g~~O '11~Jr SHOWN WHERE
GEOPHYS ICAL SURVEYS:
&> SW·I5 INTERSECTION WITH SEI SM IC REFRACTION
I LINE
SW • 15 197B, SHANNON a WILSON
SL B0-13 1980, WOODWARD -CLYDE CONSULTANTS
SLBI-22 1981, WOODWARD -CLYDE CONSULTANTS
SE I SMIC VELOCITY CHANGE
I ~~O SEISMIC VELOCITY IN FEET PER SECOND
BOREHOLES'
BH·I
LITHOLOGYi' F• FRACTURE
ZONE
S• SHEAR
D H ·I USBR DIAMOND CORE BORING
BH·I
AH ·GI
OTHER :
DC·I ~
@)
Ml
F l
NOTES
AAI DIAMOND CORE BORING
AAI AUGER HOLE
INTERSECTION WITH GEOLOGIC
SECTION DC · I
GEOLOG IC FEATURE DESCRIBED I N
SECTION 7.1.
MAF IC DIKE DESCRIBED IN SECTION 7.1.
FELSIC DIKE DESCR IBED IN SECTION 7.1.
SECTION LOCATION SHOWN ON FIGURE 7. 3 .
2. VERTICAL a HORI ZONTAL SCALES EQUAL.
3. SURFACE PROFILE FROM I " • 200'
TOPOGRAPHY, RaM, 198 1.
4 . EXPLORATION LOGS AND SEISM IC LINE SECTIONS
SHOWN IN APPEND ICIES C,E,H AND I .
5. EXTENT OF SHEARS, FRACTURE ZONES, AND
ALTERATION ZONES ARE INFERRED BASED ON
GEOLOG IC MAPPING A ND SUBSURFACE
EXPLORATIONS,AND ARE SUBJ ECT TO VER IFICATION
THROUGH FUTURE DETAILED INVESTIGAT IONS.
SCALE ~0~~~10!5ii0iiiiiiiiiiliii2~0 0 FEET
FIGURE 7,4
1!!00
lObo
!!00
SW-158 ~ED DC-6 j~~~CTEO 62~N 1
SUSITNA i
ogo•-AZ I MUTH ---.. 270•
OF SECTION
LOOKING SOUTH
R IVER BORROW SITE G SUS ITNA RIVER :i'" £8i
L~~~~) (AL~~~~::~ FAN) FPS ·.;•:.·; ..•. , .. , (LOOKING DOWNSTREAM) .1 ~APPARENT
DIP
~---~.:.·.!.'"·~--_. j!/ 200 AT 190'
--~'" ;{? "'"' ...
-t.RQO
100 30 0
L.__l__j EL.
-1212
-646
BH-2
DEVIL CANYON
GEOLOGIC SECTION DC-2
DC-3
~
I
I TREND
3!!!!'
~ M3
PROJECTED
320'
TREND 345'
TREN~
325' I
PROJECTED I
.
rF 7 .
I
I
I
I
~
I
1!100
1000
500
LEGEND
LITHOLOGY:
OVERBURDEN, UNDIFFERENTIATED
ARGILLITE AND GRAYWACKE
INFERRED ORIENTATION OF BEDDING /
FOLIATION, APPARENT DIP WHERE NOTED
FELSIC DIKE , WIDTH SHOWN WHERE
GREATER THAN 10 FEET
APPROX IMATE TOP OF ROCK
LITHOLOGIC, DASHED WHERE INFERRED
STRUCTURE:
.-·--, SHEAR, WIDTH SHOWN WHERE GREATER L ._j THAN 10 FEET
c~:= ~~:~J~:ET~g~~O '11~l~ SHOWN WHERE
GEOPHYSICAL SURVEYS:
4' sw -l5 INTERSECTION WITH SEISMIC REFRACTION
I LINE
SW -15 1978, SHANNON a WILSON
SL 80-13 1980, WOOOWARD-CLYDE CONSULTANTS
SL81-22 1981,WOODWARO-C LYDE CONSULTANTS
SEISMIC VELOCITY CHANGE
~~~ SEIS MIC VELOCITY IN FEET PER SECOND
BOREHOLES:
DH-1
BH -I
AH -GI
BH-1
LITHOLOGY~· F• FRACTURE
ZONE
S• SHEAR
USBR DIAMOND CORE BORING
AAI DIAMOND CORE BORING
AAI AUGER HOLE
OTHER :
DC·I -J,
®
INTERSECTION WITH GEOLOGIC
SECTION DC-I
GEOLOGIC FEATURE DESCRIBED IN
SECTION 7.1.
M I MAFIC DIKE DESCRIBED IN SECTION 7.1.
F I FELSIC DIKE DESCRIBED IN SECTION 7.1.
NOTES
I. SECTION LOCATION SHOWN ON FIGURE 7. 3 .
2 . VERTICAL a HORIZONTAL SCALES EQUAL.
3. SURFACE PROFILE FROM I" • 200'
TOPOGRAPHY, RaM, 19BI.
4. EXPLORATION LOGS AND SEISMIC LINE SECnONS
SHOWN IN APPENDICIES C,E,H AND I .
5. EXTENT OF SHEARS, FRACTURE ZONES, AND
ALTERATION ZONES ARE I NFERRED BASED ON
GEOLOGIC MAPPING AND SUBSURFACE
EXPLORATIONS,AND ARE SUBJECT TO VERIFICATION
THROUGH FUTURE DETAILED INVESTIGATIONS.
SCALE 0~~~10~0~~2~00 FEET
FIGURE 7.5
LEGEND
LITHOLOGY:
OVERBURDEN ,UNDIFFERENTIATED
ARGILLITE AND GRAYWACKE
INFERRE D ORIENTATION OF BEDDING/
FOLIATION, APPARENT DIP WHERE NOTED
~'~~ FELSIC DIKE, WIDTH SHOWN WHERE
12::.:;.:~ GREATER THAN 10 FEET r"> MAFIC DIKE, WIDTH SHOWN WHERE
L-,,_f GREATER THAN 10 FEET
CONTACTS:
APPROXIMATE TOP OF ROCK
---LITHOLOGIC. DASHED WHERE INFERRED
STRUCTURE:
r-·-, SHEAR, WIDTH SHOWN WHERE GREATER L._j THAN 10 FEET c :J ~~~~J~:ET~2~~0 '11~J~ SHOWN WHERE
GEOPHYSICAL SURVEYS:
4'> sw-15 INTERSECTION WITH SEISMIC REFRACTION
I LINE
SW ·15 1978, SHANNON a WILSON
SL 80·13 1980, WOOOWARD-CLYDE CONSULTANTS
SL81·22 1981,WOODWARD-CLYDE CONSULTANTS
SEISMIC VELOCITY CHANGE
~~~ SEISMIC VELOCITY IN FEET PER SECOND
1500
E
"' ...
z
0
5i > ~
1000
POWERHOUSE, TRANSFORMER GALLERY a SURGE CHAMBER
PROJECTIED 390' E
BOREHOLES :
BH·I
LITHOLOGY~· F• FRACTURE
ZONE
S • SHEAR
DH ·I USBR DIAMOND CORE BORING
B H • I AAI DIAMOND CORE BORING
AH -Gl AAI AUGER HOLE
OTHER:
DC·I ~
@)
Ml
F l
NOTES
INTERSECTION WITH GEOLOGIC
SECTION DC · I
GEOLOGIC FEATURE DESCRIBED IN
SECTION 7.1.
MAFIC DIKE DESCRIBED IN SECTION 7.1.
FELSIC DIKE DESCRIBED IN SECTION 7.1.
SECTION LOCATION SHOWN ON FIGURE 7. 3 .
2. VERTICAL a HORIZONTAL SCALES EQUAL.
3. SURFACE PROFILE FROM 1" • 200'
TOPOGRAPHY, R a M,1981.
4. EXPLORATION LOGS AND SEISMIC LINE SECTIONS
SHOWN IN APPENDICIES C,E ,H AND I .
5. EXTENT OF SHEARS, FRACTURE ZONES, AND
ALTERATION ZONES ARE INFERRED BASED ON
GEOLOGIC MAPPING AND SUBSURFACE
EXPLORATIDNS,AND ARE SUBJECT TO VERIFICATION
THROUGH FUTURE DETAILED INVESTIGATIONS.
MAIN SPILLWAY
APPROACH
CHANNEL
r-,;
/j I
lj I I f.--TREND ~ 1
/ 't 325° ~
ACCESS
TUNNEL~
~~, I
'I '/ r ~ ~/ ~J
1/ .
500
o·-AZIMUTH -lBO"
OF SECTION
LOOKING UPSTREAM
CREST OF MAIN DAM EL.I463'
.
/
FELSIC
DIKE(?)
" S,F
AREA OF OPEN
JOINTS ..._
(DIAGRAMMATIC)
TREND 325•
SL80·22C
PROJECTED
IBO'E
joc-7
1
,.,.-DIVERSION L.J TUNNEL
I BOTTOM
PROJECTED L
• 105' W r TREND 340°
~TREND 320• I
l kB
i-n /
DEVIL CANYON
GEOLOG IC SECTION DC-3 SCALE
8H·3
PROJECTED
30' E SL 80·15
i
CREST OF SADDLE DAM EL.I472'
POND
1500
1000
FIGURE 7 .6
E
"' !!:
z
0
1~00
~ 1000
i!'; ....
"'
500
DC·2
l
oo-A ZI MUTH __...180o
OF SECT ION
LOOKING UPSTREAM
S,F
~
BOITOM
PROJECTED
ro 'w
DC-7
/DIVERSION
0
TUNNEL
I PROJ ECTED 1 90' AT 150•
r-TREND 330°
®-t
I
DEVIL CANYON
GEOLOGIC SECTION DC -4
1500
1000
500
LEG END
LITHOLOGY :
OVERBURDEN ,UNDIFFERENTIATED
ARGILLITE AND GRAYWACKE
INFERRED OR IENTATION OF BE DD ING /
FOLIATION , APPARENT DIP WHERE NOT ED
FELSIC DIKE , WIDTH SHOWN WHERE
GREATER THAN 10 FEET
i"~ MAFIC DIKE , WIDTH SHOWN WHERE L...._..-.1 GREAT ER THAN 10 FEET
CON TACTS:
APPROX IM ATE TOP OF ROCK
---LITHOLOGIC , DASHED WHERE INFERRED
STRUCTURE :
r·--, SHEAR, WIDTH SHOWN WHERE GREATER L ._j THAN 10 FEET
=~:= ~~:~J~:\Jg~~0 11~J~ SHOWN WHERE
GEOPHYSICAL SURVEYS :
.!'> SW _15 INTERSECTION WITH SEISM IC REFRACTION
I LINE
SW • 15 1978, SHANNON 8 WILSON
SL 80·13 1980, WOOOWARD -CLYDE CONSULTANTS
SLBI-22 1981, WOODWARD-CLYDE CONSULTANTS
SE ISMIC VELOCITY CHANGE
IZF~O SEISMIC VE LOCITY IN FEET PER SECOND
BOREHOLES=
DH-1
BH ·1
AH ·GI
BH-1
LITHOLOGY ~· F FRACTURE
• ZONE
S• SHEAR
USBR DIAMOND CORE BOR ING
AAI DIAMOND CORE BORING
AAI AUGER HOLE
OTHER :
DC·I -!-
@
M l
Fl
NOTES
INTERSECTION WITH GEOLOGIC
SECTION DC· I
GEOLOGIC FEATURE DESCRIBED IN
SECTION 7.1.
MAF IC DIKE DESCRIBED IN SECTION 7.1.
FELS IC DIKE DESCRIBED IN SECTION 7.1.
I. SECTION LOCATION SHOWN ON F IGURE 7 . 3 .
2. VERT ICA L 8 HORI ZONTAL SCALES EQUA L.
3. SURFACE PROFILE FROM I" • 200'
TOPOGRAPHY, R 8 M,1981.
4 . EXPLORATION LOGS AND SEISMIC LINE SECTIONS
SHOWN IN APPENOIC IES C,E,H AND I .
5. EXTENT OF SHEARS, FRACTURE ZONES, AND
ALTERATION ZONES ARE INFERRED BASED ON
GEOLOG IC MAPPING A ND SUBSURFACE
EXPLORATIONS,ANO ARE SUBJECT TO VERIFICATION
THROUGH FUTURE DETAILED INVESTIGAT IONS.
SCALE O~~~li00iiiliiiiiiiiiii~2~00 FEET
FIGURE 7. 7
;:::
"' "' ...
z
0
~ ~
"' ..J
"'
ACCESS
TUNNELb
~ l '1 ~ ~ . ~ "'
PROJECTED 180'
ALONG TREND
~ OF 335"
~ ~
-AZIMUTH 171 • 351 • OF SECTION-
LOOKING UPSTREAM
SW·17A
OPEN JOINT ~ (DIAGRAMM ATIC)
TREND 295•
SL 81·22
DH-8 i
PROJECTED
90'W I
---
15,000-19,000 FPS
"• ROO 100 50 0
l__..L___l EL ,
----1318
=--1288
DH-5
s
"• ROO 100 50 0
l__j__j EL,
-1283
--1263
DH·6
·i', .
10,700 FPS \'~
\~\ \\
DEVIL CANYON
GEOLOGIC SEC TI ON DC-5
·~-~ ~~· \\
v\ \-~\l ~~ \\\• '''"'
1500
1000
500
LEGEND
LITHOLOGY :
OVERBURDEN ,UNDIFFERENTIATED
ARGILLITE AND GRAYWACKE
INFERRED ORIENTATION OF BEDDING/
FOLIATION, APPARENT DIP WHERE NOTED
&sill ~~~~M~~~·A~I%HF~~$WN WHERE
r .. > MAFIC DIKE, WIDTH SHOWN WHERE
1--._j GREATER THAN 10 FEET
CONTACTS :
APPROXIMATE TOP OF ROCK
---LITHOLOGIC, DASHED WHERE IN FERRED
STRUCTURE : c:=:J ~~~~Rj<f1~~~/HO WN WHERE GREATER
c:::J ~~~gJ~:ETJ2~~o "P~J~ SHOWN WHERE
GEOPH YSICAL SURV EYS:
4> SW-I5 INTERSECTION WITH SEISMIC REFRACTION
I LINE
SW -15 1978 , SHANNON a WILSON
SL B0-13 1980, WOODWARD-CLYDE CONSULTANTS
SL81-22 1981, WOOD WARD-CLYDE CO NSULTANTS
SEISMIC VELOCITY CHANGE
12F~O SEISMIC VELOCITY IN FEET PER SECOND
BORE HOLES:
BH-1
LI THOLOGY~-F FRACTURE
• ZONE
S• SHEAR
DH-1
BH ·1
AH ·GI
OT HER :
D C-I~
@
Ml
Fl
NOTES
USBR DIAMOND CORE BORING
AAI DIAMOND CORE BORING
AAI AUGER HOLE
INTERSECTION WITH GEOLOGIC
SECTION DC· I
GEOLOGIC FEATURE DESCRIBED IN
SECTION 7,1.
MAFIC DIKE DESCRIBED IN SECTION 7, L
FELSIC DIKE DESCRIBED IN SECTION 7.1.
SECTION LOCATION SHOWN ON FIGURE 7 , 3.
2. VE RTICAL a HORIZONTAL SCALES EQUAL.
3, SURFACE PROFILE FROM I" • 200'
TOPOGRAPHY, RaM, 1981,
4 , EXPLORATION LOGS AND SEISMIC LINE SECTIONS
SHOWN IN APPENDICIES C,E,H AN D I.
5. EXTENT OF SHEARS, FRACTURE ZONES, AND
ALTERATION ZONES ARE INFERRED BASED ON
GEOLOGIC MAPPING A ND SUBSURFACE
EXPLORATIONS,AND ARE SUBJECT TO VERIFICATION
THROUGH FUTURE DETAILED INVESTIGATI ONS,
SCALE O~~~~IO~Oi;;;;;iiiii~2~00 FEET
FIGURE 7.8
1!100
....
"' "' ...
~ ;::
~
"' -' "'
1000
500
oc-8
SUSITNA RIVER
AZIMUTH o
oo-OF SECTION-ISO
LOOKING UP STREAM
BORROW SITE G
(ALLUVIAL FAN )
AH-G2
PROJ ECTED
90'E
--
APPARENT
~ DIP
'
SW-15
DC-I
l
DEVIL CANYON
GEOLOGIC SEC T ION DC-6
1500
BORROW SITE G
(RIVER TERRACES)
500
LEGEND
LITHOLOGY :
OVERBURDEN ,UNDIFFERENTIATED
ARGILLITE AND GRAYWACKE
INFERRED ORIENTATION OF BEDDING/
FOLIATION, APPARENT DIP WHERE NOTED
FELSIC DIKE, WIDTH SHOWN WHERE
GREATER THAN 10 FEET
MAFIC DIKE , WIDTH SHOWN WHERE
GREATER TH AN 10 FEET
CO NTACTS:
APPROXIMATE TOP OF ROCK
LITHOLOGIC, DASHED WHERE INFERRED
STRUCTURE:
,-·--, SHEAR, WIDTH SHOWN WHERE GREATER L_ _ _j THAN 10 FEET c:=:J ~~:g~:ETJ2~~o1~J~ SHOWN WHERE
GEOPHYSICAL SURVEYS :
<!> SW·I5 INTERSECTION WI TH SEISMIC REFRACTION
I LINE
SW ·15 1978, SHANNON 8 WILSON
SL 80·13 19 80, WOODWARD-CLYDE CONSULTANTS
SL81·22 1981, WOODWARD-CLYDE CONSULTANTS
SEISMIC VELOCITY CHANGE
12F~O SEISMIC VELOCITY IN FEET PER SECOND
BOREHOLES=
BH-1
LI THOLOGY~·-
F-FRACTURE
• ZONE
S • SHEAR
D H • I USBR DIAMON D CORE BORING
B H • I AA I DIAMOND COR E BORING
AH • Gl AA I AUGER HOLE
OTH ER:
DC-I-!-
(§)
Ml
INTERS ECTI ON WI T H GEO LOGIC
SECTION DC· I
GEOLOGIC FEATURE DESCRIBED I N
SECTION 7.1.
MAFIC DIKE DESCRI BED IN SECTION 7.1.
F I FELSIC DIKE DESCRIBED IN SECT ION 7.1.
NOT ES
SECTION LOCATION SHOWN ON FIGURE 7. 3 .
2 . VERTICAL a HORIZONTAL SCALE S EQUAL.
3. SURFACE PROFILE FROM 1" • 200'
TOPOGRAPHY, REI M,I98 L
4. EXPLORATION LOGS AND SEIS MIC LINE SECTIONS
SHOWN IN APPENDIC IES C,E,H AND I .
5. EXTENT OF SHE ARS , FRACT UR E ZONES , AND
ALTERATION ZONES ARE IN FERRED BASED ON
GEOLOG IC MAPPI NG AND SUBSUR FACE
EXPLORATIONS,AND ARE SUBJECT TO VERIFICATION
THR OUGH FU TURE DETAILED INVESTIGATIONS.
SC ALE O~~~I~00~--~2~0 0FEET
FIGURE 7 .9
1000
;:
LIJ
LIJ
~
z
0
i= ~
1000 f--
LIJ
.J
LIJ
f--
-
-
-
500 -
DEPTH OF OV ERBURDEN
NCYT KNOWN
fJ2l
DIP
SUSITNA RIVER
{LOOKING UPSTREAM)
oes•-. A Z I MUTH ----268•
OF SECTION
LOOKING SOUTH
BORROW SITE G
-1500
-
~I -
ii -
i
{ALLUVIAL FAN) SW-I~ I --
~~O~~~TED SW -16 :p~ECTED
185'~ i j
11,150 FPS
DEVIL CANYON
GEOLOGIC SECTION DC-7
SHEET I OF 3
-1000
-
-
-
-
-500
LEGEND
LITHOLOGY:
OVERBURDEN, UNDIFFERENTIATED
ARGILLITE AND GRAYWACKE
INFERRED ORIENTATION OF BEDDING/
FOLIATION, APPARENT DIP WHERE NOTED
FELSIC DIKE, WIDTH SHOWN WHERE
GREATER THAN 10 FEET
MAFIC DIKE, WIDTH SHOWN WHERE
GREATER THAN 10 FEET
CONTACTS:
APPROXIMATE TOP OF ROCK
LITHOLOGIC, DASHED WHERE INFERRED
STRUCTURE: c:::J ~~~~Ri611fJ~TSHOWN WHERE GREATE R
c::J ~~~~f~~ETJf~~O ~~J~ SHOWN WHERE
GEOPHYSICAL SURVEYS :
~ sw-15 INTERSECTION WITH SEISMIC REFRACTION
I LINE
SW -15 1978, SHANNON 8 WILSON
SL B0-13 1980, WOODWARD-CLYDE CONSULTANTS
SLBI-22 1981, WOODWARD-CLYDE CONSULTANTS
SEISMIC VELOCITY CHANGE
12F~O SEISMIC VE L OCITY IN FEET PER SECOND
BOREHOLES =
BH -1
LITHOLOGY~··
F• FRACTURE
ZONE
S• SHEAR
USSR DIAMOND CORE BORING
BH-I AAI DI AMOND CORE BORING
AH -Gl AA I AUGER HOLE
OTHER :
DC-I _J,
@
Ml
Fl
NOTES
INTERSECTION WITH GEOLOGIC
SECTION DC-I
GEOLOGIC FEATURE DESCR IBED IN
SECTION 7.1 .
MAFIC DIKE DESCRIBED IN SECTION 7.1.
FELSIC DIKE DESCRIBED IN SECTION 7.1.
SECTION LOCATION SHOWN ON FIGURE 7. 3.
2. VERTICAL 8 HORIZONTAL SCAL E S EQUAL .
3. SURFACE PROFILE FROM I" • 200'
TOPOGRAPHY, R8 M •• l981.
4. EXPLORATION LOGS AND SEISMIC LIN E SECTIONS
SHOWN IN APPENDICIES C,E,H AND I .
5. EXTENT OF SHEARS, FRACTURE ZONES , AND
ALTERATION ZONES ARE INFERRED BASED ON
GEOLOGIC MAPPING AND SUBSURFACE
EXPLORATIONS,AND ARE SUBJECT TO VERIFICATION
THROUGH FUTURE DETAILED INVESTIGATIONS.
SCALE 0~~~~100iiil;iiiiii~200 FEET
FIGURE 7.10
11500
BORROW SITE G
liDO
oaa•___., AZ I MUTH ----..268•
OF SECTION
LOOKING SOUTH
RIVER FLOW_..
BH-3
PROJ ECTED
180' N
OH-IO
PR OJECTED
IIO'N
OH -1
PROJECTED
20'S
Sl 80 -1 2
t
THRUST 8LOCK
. I ~ I . TREND 32~'. ~M3 ~ """'
·IL PRO~ECTEO
PROJECTED 2 80 S
~I @--!
330' "'
160' s
~9xm5~
TREND 350'
DEVIL CA NYO N
GEOLOGIC SECT ION DC-7
SHE ET2 0F 3
I
~!
1500
1000
500
LEGEND
LITHOLOGY :
OVERBURDEN, UNDIFFERENTIATED
ARGILLITE AND GR AYWACK E
INFERRED ORIENTATION OF BEDDING /
FOLIATION, APPARENT DIP WHERE NOTED
c.~.i_-:,_~.'-~.:z. FELSIC DIKE, WIDTH SHOWN WHERE ~-~ GREATER THAN 10 FEET
r"> MAFIC DI KE, WIDTH SHOWN WH ERE
L-_._J GREATER THAN 10 FEET
CO NTACTS :
APPROXIMATE TOP OF ROCK
LITHOLOGIC , DASHED WHERE INFERRED
STRUCTU RE:
:·! SHEAR, WIDTH SHOWN WHERE GREATER
L-. ___1 THAN 10 FEET
[:: :J ~~:~J~:En~g~~O "'ti~J~ SHOWN WHERE
GEOP HYSI CAL SURVEYS :
.e-sw-15 INTERSECTION WITH SEISMIC REFRACTION I LINE
S W -15 1'378, SHANNON a WILSON
SL 80"13 1'380, WOODWARD-CLYDE CONSULTANTS
SLSI -22 1'381, WOODWARD-CLYDE CONSULTAN TS
SE ISMIC VELOCITY CHANGE
12F~O SEISMIC VELOCITY IN FEET PER SECOND
BOREHOLES =
BH-1
LITHOLOGY~·
F • FR~~~~RE
S• SHEAR
0 H-I USSR DIAMOND CORE BORING
B H -I AAI DIAMOND CORE BORING
AH -GI AAI AUGER HOLE
OTHER :
OC·I,!.
@
M l
Fl
NOTES
INTERSECT ION WITH GEOLOGIC
SECTION DC-I
GEOLOGIC FEATURE DESCR I BED IN
SECTION 7.1.
MAFIC DIKE DESCRIBED IN SECTION 7.1.
FELSIC DIKE DESCRIBED IN SECTION 7.1.
I. SECTION LOCATION SHOWN ON FIGURE 7.3 .
2 . VERTICAL a HORIZONTAL SCALES EQUAL .
3. SURFACE PROFILE FROM 1" • 200'
TOPOGRAPHY , R a M ,l'381.
4. EXPLORATION LOGS AND SEISMIC LINE SECTIONS
SHOWN IN APPENDICIES C,E,H AND I.
5. EXTENT OF SHEARS, FRACTURE ZON ES, AND
ALTERATION ZONES ARE INFERRED BASED ON
GEOLOGI C MAPPING AND SUBSURFACE
EXPL.ORATIONS,AND ARE SUBJECT TO VERIFICATION
THR OUGH FUTURE DETAILED INVESTIGAT IONS.
SCALE 0~~~15oo;.iiiiii~2~00 F EET
FIGURE 7.10
.... ... ... ...
z
1500
0 1000 ~
"' ...J
"'
500
"• ROD 100 so 0
L____j__J E L .
• -1447
-373
DH-8
I~ Dc-5 .~ t
,
:H-8 SW-17
PROJECTED i
I 75' N
BOTTOM
PROJECTED
55'S
oaa• ...---A ZIMUTH ____.. 268 •
OF SECTION
LOOKING SOUTH
RIVER FLOW-
@
~IN FERRED SHEAR l TREND 320• ~PPARENT
DI P
F4
TREND
DEVIL CANYON
GEOLOGIC SECTION DC-7
SHEET 3 OF 3
1500
1000
500
LEGEND
LITHOLOG Y:
OVERB URDEN, UNDIFFERENT IATED
ARGILLITE AND GRAY WACKE
INFERRED ORIENTATION OF BEDDING /
FOLIATION, APPARENT DIP WHER E NOTED
{EB} m~M~~~·A~~~1HF~~~WN WHERE
APPROXIMATE TOP OF ROCK
---LITHOLOGIC, DASHED WHERE INFERRED
STRUCTURE:
r-·--, SHEAR , WI DTH SHOWN WHERE GREATER
l-,__J THAN 10 FEET
.-"! FRACTURE ZONE, WIDTH SHOWN WHERE
L . _ __j GREATER THAN 10 FEET
GEOPHYSICAL SURVEYS :
.£1 SW -I5 INTERSECTION WITH SEISMIC REFRACTION I LINE
SW -15 1978, SHANNON a WILSON
SL 8 0-13 1980, WOO DWARD -CLYDE CONSULTANTS
SL81-22 1981 , WOODWARD -CLYDE CONSULTANTS
SEISMIC VELOCITY CHANGE
12F~O SEISMIC VELOCITY IN FEET PER SECOND
BOREHOLES:
BH-1
LI TH OLOG Y {~' F• FRACTURE
ZONE
S • SHEAR
DH -1 USSR DIAMO ND CO RE BORING
B H -I AAI DIAMOND CORE BORING
AH -GI AAI AUGER HOLE
OTHER :
DC-I _J,
@
INTERSECTION WITH GEOLOGIC
SECTION DC -I
GEOLOGIC FEATURE DESCRI BED IN
SECTION 7 . I .
Ml MAF IC DIKE DESCRIBED IN SECTION 7.1.
F I FELSIC DIKE DESC RIBED IN SECTION 7.1.
NOTES
SECTIO N LOCATION SHOW N ON FIGURE 7. 3 .
2 . VE RTI CAL a HORIZONTAL SCALES EQUAL.
3. SURFACE PROFILE FROM I " • 200'
TOPOGRAPHY, Ra M,~98 1.
4 . EXPLORATION LOGS AND SEIS MIC LINE SECTIONS
SHOWN IN APPENDICIES C,E,H AND I .
5. EXTENT OF SHEARS, FRACTURE ZONES, A ND
ALTERATION ZONES ARE INFERRED BASED ON
GEOLOGIC MAPPING A ND SUBSURFACE
EXPLORATIONS,AND ARE SUBJECT TO VERIFICATION
THROUG H FUTURE DETAILED INVESTIGATIONS.
SCALE 0~~~1§00ii;;;;iiiiiiiii2~00 FEET
FIGURE 7.10
NOTES:
ACROSS RIVER FROM CHEECHAKO CREEK
RIVER LEVEL-NORTH BANK
I. GRADED BEDS OF ARGILLITE/GRAYWACKE.
2 . STRATIGRAPHIC TOP TO LOWER LEFT.
DEVIL CANYON
TYPICAL ARGILLITE /GRAYWACKE
FIGURE 7.11
WEST
RIVER
FLOW
M3 Ml GF 4 GF 3
NOTES:
I. DIKES Ml AND M3 DESCRIBED IN SECTION 7.1.
2. GEOLOGIC FEATURES GF 3,GF4,AND GF5 DESCRIBED
IN SECTION 7.1.
DEVIL CANYON
AERIAL VIEW OF SITE
EAST
FIGURE 7. 12
E
JOINT STATION
DCJ-2
N ~100
JOINT STATION
DCJ-1
N~93
E
SET
I
APPROXIMATE
DAM
CENTERLINE
c;::>
SET
JJI:
N
JOINT STATION
DCJ-3
N~ 100
E
G
SET
I
Q
s
SET
\JJW r--, I
+(.._'_/ ~
N
SET :n:
COMPOSITE JOINT PLOT
SOUTH BANK
N~479
w
/
~ ...
~--···
DEVIL CANYON
JOINT PLOTS
s
N
COMPOSITE JOINT PLOT
NORTH BANK
N~714
DCJ-4
s
~SET ~_0/-,. w
... --··· JOINT STATION------.._
DCJ-4 ···----N~IOO
NOTES
I. CONTOURS ARE PERCENT OF JOINTS PER I% OF AREA.
CONTOURS SHOWN-1,3,5,7,10,15, Eli 20%.
2. N EQUALS NUMBER OF DATA POINTS.
3. COMPOSITE PLOTS INCORPORATE ALL JOINT DATA. JOINT
STATION PLOTS CONTAIN DATA FROM SPECIFIC JOINT
STATIONS.
4. FOR JOINT PLOTIING METHOD SEE FIGURE 6.12.
FIGURE 7.13
"1 J l l l
-X -xx-FELSIC DIKE
-·-MAFIC DIKE
SHEAR
-··-FR 50..)-BE~;~NURE ZONE
70..Jiill""' JOIN G/FOLIATION T ,INCLINED
_________ _iFHIGURE 7.14
COMPRESSION TEST FAILURE
ALONG HEALED DISCONTINUITY
o-t = 1471 psi
GRAYWACKE
TYPICAL TENSILE STRENGTH TEST
DEVIL CANYON
ROCK TESTS
COMPRESSION TEST FAILURE
THROUGH INTACT ROCK
TYPICAL COMPRESSION TEST
WITH STRESS-STRAIN READINGS
FIGURE 7 .15
0.09
(+)
0.06
(+I
0.06
24
21
0.03 0 0.03
STRAIN (%)
24
0.03 0 0.03
STRAIN (%)
0.06 0.09
8
0.06 0.09
ROCK "TYPE: GRAYWACKE
FAILURE STRESS: 23,453 psi
Er5o•II.6XI06 psi, v=0.22
Es•11.6XIo6 psi, v=o.zz
BOREHOLE: BH-1, SAMPLE No.:BQ-48
DEPTH • 510.65 FEET
L;0 "2.57 r • 168.6 pcf
0.12 0.15 0.18 0.21
H
ROCK TYPE: GRAYWACKE
FAILURE STRESS: 28,39S·pei
Erso•I0.9MI0 6 psi, v "0.23
Es•I0.41ti06 ps1, v"0.23
BOREHOLE: BH-3, SAMPLE No.: D-3-276.0
DEPTH • 276.0 FEET
L,0 ·z~s y,t80.4pcf
0.12 0.15 0.18 0.21 0,24
H
0,06
(+)
]
,.
0 ~ ~ 15 r
0
J 4 x 4 12
9
6
'
ROCK TYPE: ARGILLITE
FAILURE STRESS: 17,487 psi
Erso•II.Bxlci6 psi
Es•ll.81tl06p1si
BOREHOLE• BHt3, SAMPLE No.: 0-3-89.6
DEPTH I" 89.6 FEET
Lfo •2.58 1 y .. 170.3 pcf
0 0.03 0.06 0.09 0.12 : 0.15
'(-) STRAIN (%)
] ,.
0
0
~
~ 15 r w
J
4 x
4 12
0
ROCK TYPE: GRAYWAdKE
FAILURE STRESS: 13,420 psi
ET.so•S.6xi06psl, ]v•O.I7
Es•9.7xi06 psl, v 1•0.19
BOREHOLE' BH-2., SAMPLE No. 80-71
DEPTH. 445.2. FEET I
L;D • 2..5o r ~169.2. pet
0.03 0 0.03 o.os o.o9 0.12. 1 o.l5 o.1s 0.06
t•l STRAIN (%) H
DEVIL CANYON
STATIC ELASTIC PROPERTIES
FOR ARGILLITE AN'o GRAYWACKE
0.06
{+)
12 -
~
0 ~
~ 9 r
0
LEGEND
0 AXIAL STRAIN
6 VOLUMETRIC STRAIN
CJ DIAMETRIC STRAIN
Es SECANT MODULUS
ET50 TANGENT MODULUS AT 50% FAILURE
.tl.Q.rr
SAMPLE DIAMETER •1.77M
ROCK TYPE: ARGILLITE
FAILURE STRESS: 8, 017 psi
E T50 ~ 4.4 x 10 6 psi, v • 0.20
Es=4.4xi06psi, V•0.20
BOREHOLE: BH-2, SAMPLE No.: 80-66
DEPTH • 273.0 FEET
L;0 ,. 2..61 r •16B.6 pcf
0.03 0 0.03 0.06 o.09 0.12.
H
] IB
m
~ 15
J < ~ 12
9
STRAIN ("k)
ROCK TYPE: ARGILLITE
FAILURE STRESS: 16,227 psi
ETso•l2.7~ti0 6 psl, v•O.I9
Es•l2.7xi06 psi, v~O.I9
BOREHOLE: BH-5A, SAMPLE No.: 0-5A-2.31.3
DEPTH • 2.31.3 FEET
LfD•2.64 r•I70.I pet
0.03 0 0.03 0.06 0.09 0.12
(-} STRAIN (%)
STRESS
FIGURE 7.16
180 180
160 160
Glil El
140 El l!l l!l 140
El El El El rmEI ~ El ~ c 120 El c 120 z El !> ~ El ~ 0 l!l ~
~ ~
0 100 0 100 c g 0 ~
~ ~ c c w 80 w 80 ~ ~
~ ~
888&.88
8 88 8 8 8
60 • 8 60
88 8 ~ z w
~
40 w 40 u c~
~w ~~
~0 ~u
0 0 00 0 0 0 0 0
c~
20 0.05 :;J. g; 20
~
~ w >
0 0
0 0.0!5 0.10 0.15 0.35
SHEAR DISPLACEMENT IN INCHES
100 ROCK TYPE: ARGILLITE 100
BOREHOLE: BH-2
SAMPLE: 80-68
80 DEPTH: 305.5'
80 SAMPLE AREA: 1.875 SQ. IN.
~
!!; 0
!>
0 60
0 w ~
~
0
0 60
0 w
~
~
0
~ 40 c w
~
0
~ 40 c w
~
0
20 20
20 40 60 100 120 140 160
NORMAL STRESS ( PSJ)
ARGILLITE, NATURAL JOINT, SLICK, CHLORITIZED, DRY
El
0
El[!]
EJEI El El El
i!l%J El f!\:::J EEl
El
El ~ c
GEl" z
~ A 0
~ •
AA A c A
88 A c
A A A 3 A~ A A ~ c w
~
~
0 0
00 0 0 0 0 0 0 0 0 00
000
0.05 0.10 0.15 0.20 0.25 0.~0 0.35
SHEAR DISPLACEMENT IN INCHES
ROCK TYPE: ARGILLITE
BOREHOLE: BH-5a
SAMPLE: D-5a -221.5
DEPTH: 221.5'
SAMPLE AREA: 2.468 SQ. IN.
~
!>
0
0 w
~ ~
0
~ c w
~
0
80 100 120 140 160
NORMAL STRESS {PSI)
POLISHED ARGILLITE ON MORTAR, BOND BROKEN, DRY
'
I
I
DEVIL CANYON
DIRECT SHEM TESTS
SHEET 10F 3
I
180
160
140
120
100
80
60
40
20
0
0
100
80
60
40
El
El El l!l
El El
l!l l!l l!l El
El
0 • l!l 0
0
El
88 8 8
8 8 8 8 8
8
•• <::P 00 00 00 0 0 00 0
0.05 0.10 0.15 0.20 0.25 0.30
SHEAR DISPLACEMENT IN INCHES
ROCK TYPE: ARGILLITE
BOREHOLE: BH-5a
SAMPLE: o-sa-221.5
DEPTH: 221.5'
SAMPLE AREA: 2.468 SQ. IN.
NORMAL STRESS (PSI)
POLISHED ARGILLITE ON ARGILLITE, DRY
0.35
•
LEGEND
~p PEAK FRICTION ANGLE
~R RESIDUAL FRICTION ANGLE
• PEAK VALUES
"' RESIDUAL VALUES
0 VERTICAL DISPLACEMENT
0 NORMAL LOAD • 25 PSI
8 NORMAL LOAD: 75 PSI
El NORMAL LOAD= 150 PSI
c APPARENT COHESION
ITJ FRICTION ANGLE ENVELOPE
J. MAXIMUM SHEAR BOX OISPLACEMENT 11 0.31NCHES
2. STRAIN RATE • 0.039 lN./MIN.
FIGURE 7.1.7
200 200
leO leO
160 160
GJ GJ GJ
140 GJ 140
w
0 120 w 120 0 z z ~ ~ ~ 0
" "' "' 0 100 GJ 0 100
< El El < 0
~ g
"' "' < < ~ eo ~ eo % % w w
8
60 8 88 60 .-.· IJo,
A
IJo, /Jo,!Jo,
40 40
20
0:#000 0 0 0 00 00 0 00 20
0 0
0 0.05 0.10 0.15 0.20 0.25 0.30 0.35
SHEAR DISPLACEMENT IN INCHES
100 ROCK TYPE: GRAYWACKE 100
BOREHOLE: BH-2
SAMPLE: 80-71
DEPTH: 445.2' 80 eo SAMPLE AREA: 2.473 SQ. IN.
;; w
!0 !0
w 60 • w 60 w w
~ ~
"' "' ~ ~ w w
"' 40 "' 40 < <
~ ~
% % w w
20 20
0
140 160
NORMAL STRESS (PSI)
POLISHED GRAYWACKE ON GRAYWACKE, WET
0
0
GJ GJ GJ GJ GJ
GJ
GJ.
GJ. GJ GJ w
0
El z
El ~
GJ El 0
El " EJEJ • 0 < 0 ~
"' < ~
% w
8
"'"'"' 8 8 8
88 8 88 8 8 8 /Jo,, A& 8
•••• 0 0 0 0 0 0 0 0000
0.05 0.10 0,15 0.20 0.25 0.30 0.35
SHEAR DISPLACEMENT IN INCHES
ROCK TYPE:
BOREHOLE:
SAMPLE:
DEPTH:
SAMPLE AREA:
20 40
POLISHED
GRAYWACKE
BH-1
60-73
429.0'
2.462 sa. IN.
;;;
• !0
w w ~
"' ~ w
"' <
~
% w
60 eo 100 120 140 160
NORMAL STRESS (PSI)
GRAYWACKE ON GRAYWACKE, DRY
DEVIL CANYON
DIRECT SHEAR TESTS
SHEET 2 0F 3
I
I
leO
160
140
120
GJ
100
0 El@!l EJElEI
GJ El El
El eo El El
G El G El G
60
8 IJo,
~ IJo, IJo,
IJo, A& 8
40 8
/Jo,IJo, IJo, IJo, A IJo, IJo,
0
20 0 0 0 0 0 0 0' 0 00 0 0 0 0 0
0
0 0.05 0.10 0.15 0.20 0.25 0.30 0.35
SHEAR DISPLACEMENT IN INCHES
100 ROCK TYPE: GRAYWACKE
BOREHOLE: BH-2
SAMPLE: 80-71
DEPTH: 445.2' eo SAMPLE AREA: 2.473 sa. IN.
60
40
20 •
0
0 20 40 60 eo 100 120 140
NORMAL STRESS (PSI)
POLISHED GRAYWACKE ON GRAYWACKE, DRY
160
LEGEND
~p PEAK FRICTION ANGLE
~. RESIDUAL FRICTION ANGLE
• PEAK VALUES
.a. RESIDUAL VALUES
0 NORMAL LOAD • 25 PSJ
IJo, NORMAL LOAD • 75 PS J
El NORMAL LDAO•I50 PSJ
D FRICTION ANGLE ENVELOPE
I. MAXIMUM SHEAR BOX DISPLACEMENT • 0.3 INCHES
2. STRAIN RATE • 0.039 IN. I MIN.
FIGURE 7.17
180 0 08 r 0 8 8 8
8 8 0
160
em
140
"' 120 c z
:::J
0
Q.
;!; 10 0
c 88 8 8 8 8 .. 8 0 8 8 8 .J 8 8 a: .. 80 w
X
"'
60
40 .. 000 0 0
0 0 00 0 0 0
20
0
0 0.05 0.10 0.15 0.20 0.25 0.30 0.35
SHEAR DISPLACEMENT IN INCHES
100 ROCK TYPE: GRAYWACKE
BOREHOLE : BH-1
SAMPLE: B0-51 A+B
DEPTH: 554.5'
80 SAMPLE AREA: 2.76 SQ. IN.
Ui
Q.
(/) 60 "' "' a: ....
(I)
a: .. w 40
X
(I)
20
NORMA L STRESS IPS I)
GRAYWACKE, NATURAL JOINT, SMOOTH, PLANAR, PART OPEN
200
180
160
140
"' c 120 z
:::J
~
;!;
c 100 ..
0
.J
a: .. w 80
X
"'
60
40
0
0
100
80 ·
Cii
Q.
"' 60 "' w a: ....
"' a: 40 .. w
X
"'
20
r::::J
0 r::::J
0 r::::J r::::J
0
r::::J 8 o8
8
8
o8
0
8
8
8 8
8 8 8 8
88 8 8 8 8
0
0 0 0 0
0 00 0 0
.c:F00 0
0.05 0 .10 0.15 0.20 0 .25
SHEAR DISPLACEMENT IN IN CHES
ROCK TYP E :
BOREHOLE :
GRAYWACKE
BH -2
SAMPLE: B0-71
DEPTH: 445.2'
SAMPLE AREA . 2.473 SQ . IN .
20 40 60 80 100
NORMAL STRESS IPS I)
0 .30 0 .35
120 140
POLISHED GRAYWACKE ON MORTAR, BOND BROKEN
DEVIL CANYON
DIRECT SHEAR TESTS
SHEET 3 OF 3
16 0
LEGEND
4>P PEAK FRICTION ANGLE
4>R RESIDUAL FRICTION ANGLE
• PEAK VALUES
• RESIDUAL VALUES
0 NORMA L LOA D • 25 PSI
8 NORMA L LOAD • 75 PS I
r::::J NORMAL LOA D • 150 PSI
c APPARENT COHESION
I. MAXIMUM SHEAR BOX DISP L ACEM ENT • 0.3 INCHE S
2. STRAIN RAT E • 0 .03 9 IN . I MI N.
FIGURE 7.17
"' S.D. S.D.
UJ 6 <.> z z ..
UJ UJ a: ::;;
::0 <.> 4 <.>
0
u.
0
a: 2
UJ
"' ::;;
::0 z
10 20
UNCONFINED COMPRESSIVE STRENGTH
ARGILLITE (AAI, USGR)
U)
"' 6 <.> z
UJ n::
:::>
<.> 4 <.>
0
u.
0
a: 2
UJ
"' ::;;
::0 z
REFERENCE, LAB REPORT c-933, USBR 1960
"' S.D. S.D.
UJ 6 <.> z z
UJ ..
a: UJ
::0 ::;;
<.> 'I <.>
0
u.
0
N=21 a: 2
UJ
"' ::;;
::0 z
30 40 10 20 30
( ksi ) UNCONFINED COMPRESSIVE STRENGTH ( ksi)
z .. w ::;;
10 20 30
UNCONFINED COMPRESSIVE STRENGTH (ksi)
ALL Tl"37S (J.\1'1, USBf<)
DEVIL CANYON
GRAYWACI:E
40
UNCONFINED COMPRESSIVE STRENGTH TEST RESULTS
(AI\1, USSR)
ROCK N
ARGILLITE 21
GRAYWACKE 16
MAFIC DIKE 2
TOTAL= 39
LEGEND
N-NUMBER OF TESTS
S.D. -STANDARD DEVIATION
40
FIGURE 7.18
S.D. S.D.
30
rn w
(.) z 20
'" a::
::::>
(.)
(.)
0
lL
0
a:: w
lD :::; 10
::::>
• z
10 20
COMPRESSIVE STRENGTH
ALL DATA
30
( ksi )
.;.;J
i
DEVIL CANYdN
POINT LOAD TEST DATA
rn w
(.) z w a::
::::>
(.)
(.)
0
lL
0
a:: w
lD :::;
::::> z
rn w
(.) z w a::
::::>
(.)
(.)
0
lL
0
a:: w
lD :::;
"' z
16
12
8
4
6
4
2
LEGEND
N-NUMBER OF TESTS
S.D. -STANDARD DEVIATION
S.D. S.D.
~ 20 ~ 40
COMPRESSIVE STRENGTH ( ksi)
INTERBEDDED ARGILLITE AND GRAYWACKE
S.D. S.D.
z
<t w :::;
10 20 30
COMPRESSIVE STRENGTH ( ksi)
GRAYWACKE
N=33
40
FIGURE 7.19
-
K, COEFFICIENT OF PERMEABILITY (CM/SEC) -0
..........
to-,
0 \
' \
' \
r
-1-
ILl
ILl
IL 300 -:I:
1-
Q.
ILl
0 -ILl
...1
0 400
:I:
ILl r a:
0
CD
\ 0 \
\ "' ....
AVERAGE .......
\ ....
• PERMEABILITY ' \ \
\ \
I \
I I
I I I
~ 0\ I
MAXIMUM_)
... , ( -.... I ' 0 I I
/ /
( I
\ 0 I
\ I
r \ I \
~ /
' I \ 0
I f !---MINIMUM
100
200
I I
...1 -<1: I I
u
1-500
a:
ILl ->
I
I
I I
I I
I I
\ 0 I
' I
' I -I 600 ' I --
1\
' I""" '
700
BASED ON: AAI 80-81: BH-1-4, BH-5A-5B, BH-7
USBR HOLES: DH-1, DH-5, DH-7, DH-8, DH-9,
DH-IIC, DH-12A, DH-13, DH-148
DH-15
800
DEVIL CANYO~ ROCK PERMEABILITY
-FIGURE 7.20
1413.7
1402.8
1400
1380
1360
1340
1320
1-1300 w
w •
%
0
~ 1280
w ~ w
1260
1240
1220
1200
1180
1160
TEMPERATURE ("C I
-s -4 _, -2
0
STICK UP-0.0 FEET { 1981)
DIP-67"
40
80
r w
IIJ 120 •
w
~
0
%
% • 0
0
%
::;: 160
w
0
200
240
280
LEGEND
LITHOLOGY:
~ GROUND SURFACE
~ TOP OF ROCK
BOREHOLES:
-I
AH
8H
AUGER HOLE I ACRES AMERICAN INCORPORATED
BORE HOLE
DATA SOURCES •
INDEX OF THERMISTOR READING DATES•
< NOVEMBER 21, 1980
0 APRIL 19, 1981
X MAY 24, 19"81
0 JUNE 24, 1981
• AUGUST 3, 1981
NOVEMBER 13, 1981
0 DECEMBER 9,1981
• JANUARY 7, 1982
0
BH·I
I. LOCATION OF HOLES SHOWN ON FIGURE 5.2.
;::
w w
1213.4
1211.7
1200
1180
I 160
I 140
I 120
IL I I 00
%
0
~ > w 1080 ~ w
1060
1040
1020
1000
980
2. THERMISTOR STRINGS MANUFACTURED BY
INSTRUMENTATION SERVICES IN FAIRBANKS,ALASKA.
3. BORINGS ARE INSTRUMENTED WITH PERMANENT
MULTI-POINT THERMISTOR STRINGS, WITH TWO
THERMISTORS AT EACH READING POINT. DATA FOR
TWO POINTS IS AVERAGED.
4. THERMISTOR READOUT BOX-KEITHLEY 172 A, USED
FOR 1980 THRU 1982 READINGS.
5. AUGER HOLES AH-GII THRU AH-GI4 CONTAIN
THERMISTOR PROBES, BUT NO DATA WAS OBTAINED.
6. BORINGS ARE VERTICAL UNLESS A DIP IS INDICATED.
r w
w •
w
~
0
%
% • 0
0
% r
~ w
0
TEMPERATURE {"C)
-s
0 -· _, -1 0 2 ' 4 5
C>----!__ __ ,___ ~-<>-0--__~~ --'--e--;: ---{]
40
80
120
160
200
240
280
STICK UP-0.0 FEET (19811 I 'fR~ DIP-60"
ty I 'v
!
I
I
l
' I ' ~
II
!
'
I,
I
~~
BH·2
NOTE' DUE TO PROBLEMS ENCOUNTERED IN 1FIELD MEASUREMENTS, THE FOLLOWING
ADJUSTMENTS WERE PERFORMED TO 'cONFORM TO EXISTING RELIABLE DATA. THESE
FIXED LATERAL SHIFTS MAY NOT COR~ECT THE FULL MAGNITUDE OF THE DISCREPANCIES.
DATE OF READING
4-26-81
:S-24-BI
6-24-81
8-3-81
ADJUSTMENT SUBTRACTED
FROM CALCUI ATED READING ("C l
13.28
14.00
16.00
14.65
DEVIL CANYON
THERMISTOR DATA-DAMSITE
r w
1352.6
1346.5
1340
1320
1300
1280
1260
~ 1240
%
0
~ w 1220 ~ w
1200
1180
1160
1140
1120
TEMPERATURE {"C)
0'[--::~-4:;~~-~·~~~-~2======-~~====~0=:;:~~~~~2=::--"'r-----.·--::~· 0-------
STICK UP-O.O FEET (1981)
DtP-60"
40
80
r w
~ 120
w
~
0
%
% • 0
0
% ~ 160
0
200
/
240 ~~--~
,_,y
280L_ _____________ _L _____________ __
BH·4
NOTE' THERMISTOR DATA FOR 5-24-81 IS QUESTIONABLE AT 200 AND 250 FEET. SENSOR
AT 250 FEET WAS ERRATIC FOR 1-7-82 READING.
_, -2 'I 0 2 3"C
SCALE ~--,-"-~-;"--r--+---r-~---r-L;---r
FIGURE 7.21
REFERENCE ' BASE MAP FROM RaM ,1961-I" • 200' DEVIL CANYON
TOPOGRAPHY, RETRACED AT 25' CONTOUR S
USBR,I 960
COE, 1978
WCC,I978
{
\ \
DEVIL CANYON
BORROW SITE G PLAN
BORROW SITE G
(LOOKING NORTH)
TEST TRENCH TT-G I
(LOOKING NORTH)
LEGEND
CONTACTS:
-·-·-MAPPEOLIMIT OF BORROW SITE OR ZONE
BOREHOLES AND TEST PITS:
0 AH ·GI 1980-81, AAI AUGER BORING
• [TT K-1 7
!fPK·93 1958, USSR DOZER TRENCH
-TT-GI 1981, AAI DOZER TRENCH
GEOPHYSICAL SURV EYS '
, SW -15 SEISMIC REFRACTION SURVEY
END OR TURNING POINT-1978,
SHANNON a WILSON
OTHER:
E E
t.t CROS_S SECTION LOCATION (SEE NOTE 2)
NOTES
I. TYPICAL SECTIONS SHOWN ON FIGURE 7. 23
2 . FOR DETAIL EO GEOLOGY AND GEOLO GI C SECTIONS,
SEE FIGURES 7.3 AND 7.4 THROUGH 7.10
3 . SURFICIAL GEOLOGY SHOWN ON FIGURE 7 .2 .
4 . 25 FOOT CONTOUR INTERVAL AODED FROM SOURCE
MAP (REFERENCED) IN BORROW SITE ONLY .
5 BORROW SITE LI MITS BASED ON FIELD AND AIR PHOTO
INTERPRETATION OF BORROW MATERIAL. FINAL
LI MITS , SUBJECT TO RESULTS OF DESIGN INVESTIGATIONS.
6 BORROW MATERIAL ZONES INOICATE MAPPED VARIATIONS
IN MATERIAL TYPE .
ZONE I ALLUVIAL FAN I TERRACE DEPOSIT OF
SAND AND GRAVELS .
ZONE ][ RIVER TERRACES, SI MIL AR TO MAT ERIAL I .
ZONE m CHEECHAKO CREEK OUTWASH, BOULDERY
GRAVELS .
ZONE Ill ARGILLITE I GRAYWACKE TALUS DEPOSITS .
7 ENTIRE BORROW SITE LIES WITHIN PROPOSED
DEVIL CANYON RESERVOIR LIMITS.
8 USBR, COE EXPLORATION LOGS AS REFERENCED.
9 AAI E XPLORATION LOGS SHOWN IN APPENDIX G.
10 PHOTOS TAKEN AUGUST, 1981.
SCALE 0~~~250iii0iiiiiiiiiiiiiiiiii4~00 FEET
FIGURE 7.22
;:: SUSITNA
w RIVER w
~ lOOT z
" 9!50 EL.92~± ~ 900 w
~ w
SUSITNA
RIVER
IOOOt
950 e:;-.930±
900
1400
1300
E w 1200 !0
z
0
~ w 1100
~ w
1000
900
0900 ...__ AZIMUTH ~270 o
OF SECTIONS
SUSITNA
la RIVER
TTK-7 TTK·I7 AH-G4 TTK-20 AH·G2
.. ~~----~~;"-""-~~ll;;:.:~6f4{:"\i;iGi~~.rgE:~~;;JfS~·:··:2~:f:-: ... ;-:~-~=~~ EL.9IO±
BEDROCK
SW-15
PROJECTED 50'S
TTK-26
TTK-6
lbj
SECTION C-C
TTK-25 I a
SECTION E-E
SECTION G-G
SECTION J-J
SW-15
CREEK
.: ...
j iOOO
950
900
SW-15
PROJECTED 40' N SUSITNA
f-"'"OR"ol V'OE'OR"-.,-
...
SHALLbw
ASSUMED
BEDROCK
DEVIL CANYON
BORROW SITE G SECTIONS
1
1100
1000
900
1400
1300
1200
1100
1000
900
LEGEND
CONTACTS:
-·-·-MATERIAL LIMITS
----ASSUMED TOP OF ROCK
LITHOLOGY'
~ ARGILLITE a GRAYWACKE OUTCROPS
BOREHOLES a TEST PITS' 0 AH-GI 1980-BI,AAI AUGER BORING
-f TTK-17 19~8,US8R DOZER TRENCH
l TPK-93 195B,USBR HAND DUG TEST PIT.
• TT-GI 1981,AAI DOZER TRENCH
GEOPHYSICAL SURVEYS' t SW·I5 SEISMIC REFRACTION SURVEY END OR
TURNING POINT -1978,SHANNON tl WILSON
NOTES
I. SECTION LOCATIONS AND BORROW SITE PHOTO SHOWN ON
FIGURE 7.22.
2. FOR DETAILED GEOLOGY AND GEOLOGIC SECTIONS, SEE
FIGURE 7.3 AND 7.4 THROUGH 7.10.
3. SURFICIAL GEOLOGY SHOWN ON FIGURE 7.2.
4. VERTICAL AND HORIZONTAL SCALE 1'1.
5. SECTION ELEVATIONS FROM REFERENCED BASE MAP.
6. BORROW SITE LIMITS BASED ON FIELD AND AIR PHOTO
INTERPRETATION. FINAL MAPPED LIMITS OF BORROW
MATERIALS, SUBJECT TO RESULTS OF DESIGN INVESTIGATIONS.
7. BORROW MATERIAL ZONES INDICATE MAPPED VARIATIONS
IN MATERIAL TYPE.
ZONE I ALLUVIAL FAN I TERRACE DEPOSIT OF SAND (I a)
AND GRAVEL. COARSER AT DEPTH Ubl
ZONE Ir RIVER TERRACES,SIMILAR TO MATERIAL I
ZONE :m: CHEECHAKO CREEK OUTWASH,BOULDERY GRAVELS
ZONE I'l ARGILLITE I GRAYWACKE TALUS DEPOSITS
8. USBR,COE EXPLORATION LO~S AS REFERENCED.
9. AAI EXPLORATION LOGS SHOWN IN APPENDIX F.
10. EXPLORATIONS PROJECTED UP TO 150' ONTO SECTIONS.
II. SECTIONS STOPPED AT SUSITNA RIVER LEVEL.
0 100 200 FEET
SCALE
FIGURE 7.23
U.S. Standard Slava OpenlnQS in Inches U.S. Standard Sieve Numbers Hydrometer
r-,.....: ...:--, I'<'-, "-.,. ""'-. ".. I'
0 1ooUol_l_l5j_oo_L_L__L _ _jiOO_il_li_5LO_LL_j_ __ _jiOLU_Ll_5U__l___l _ __j_WLJ_o.C5 Lt::::::±:~~Q~I W_o.Lo5_L_L__L_ _ _jo.O.L_I W_OLOO_l5 __l____l __ QOOIIOO
BOULDERS COBBLES GRAVEL
Coarse. Fine
TOTAL NUMBER OF SAMPLES: 4 7
SAND
Medium Fine
DEVIL CANYON
BORROW SITE G
RANGE OF GRADATIONS
FINES
Silt Sizes
FIGURE 7.24
1 1 l 1 1 1 1 -1
U.S. Standard Sieve Openings in lnclles U.S. Stondord Si..,e Numbers Hydrometer
100 12 9 6 3 2 11/2 I 3/4 1/2 3/8 4 .• 10 20 40 80100 200 270 0
10 90 I
80 20 I
70 I 30 -.t::
o>
Q) ;:: 60 I 40 ,..
..c ....
50 50 Q)
c:
lL; ...
60 c: 40 ~
Qj
Q.
30 70
20 80
10 90
0 1000 500 100 !50 10 5 0.5 Ql 0.05 0.01 0.005 QOOIIOO
BOULDERS COBBLES GRAVEL
Coarse Fine
UNIT* MATERIAL
C SILT WITH SAND, GRAVEL
D SAND WITH TRACE SILT
N SANDY GRAVEL
*SEE EXPLORATORY TRENCH GEOLOGIC
SECTIONS, APPENDIX G
SAND FINES
Medium Fine Silt Sizes
NO. OF SAMPLES MATERIAL
4
9 rrl\"'· .. ~ ![,~·~.p ~ p GRAVELLY SAND, SANDY GRAVEL
3 8-:}:'}i z SANDY GRAVEL WITH SILT, COBBLES
DEVIL CANYON
BORROW SITE G
STRATIGRAPHIC UNIT GRADATIONS
NO. OF SAMPLES
4
3
24
FIGURE 7.25
1
-~
01 •• 3:
>. ..:a ...
41 ... ....
0
0
(.)
-.:
41
0 ...
Ill
Q.
0 0
0 0
0 ~ 0
0 Q)
"' (J) "' "" w
N 3,212,000
N 3,214,000
QUARRY SITE
N 3,216,000
N 3,218,000 (
REFERENCE> BASE MAP FROM USGS 1=63,360 ALASKA QUADRANGLE
TALKEETNA MOUNTAINS (0-5).
COORDINATES IN FEET, ALASKA STATE PLANE
(ZONE 4)
0
0
0
"' "' w
)
0
0
0 ...
(!J
w
DEVIL CANYON
QUARRY SITE K
0
0
0
"' "' w
0
0
0
0
"' w
SCALE
LEGEND
-·-MATERIAL LIMITS
® SAMPLE LOCATION
NOTES
I. CONTOURS TRACED FROM ENLARGED,
REFERENCED BASE MAP, AT 100'
INTERVAL.
2. MATERIAL LIMIT SHOWN IS OUTCROP
LIMIT AS DETERMINED FROM AIR PHOTO
INTERPRETATION. NORTH FACES OF
SITES ARE EXPOSED ROCK CLIFFS, AND
LOCATION OF SAMPLES.
3.QUARRY MATERIAL IS A BIOTITE
GRANODIORITE WITH SOME ARGILLITE
INCLUSIONS. MAPPED AREA CONSISTS
OF A SERIES OF NORTH-FACING SHEAR
BLUFFS 50-100' IN HEIGHT, FORMING
THE FACE OF A DIORITE PLLITON
WITH EXPOSURE IN EXCESS OF 1/2
SQUARE MILE.
4. ENTIRE QUARRY SITE LIES OUTSIDE OF
PROPOSED RESERVOIR LIMITS.
FIGURE 7.26
-
-I
-
-I.
r
"""" I
-i
-I
GLOSSARY*
Active Layer or Active Zone -The surficial layer of ground above the
permafrost tab 1 e that thaws each summer and refreezes each fa 11, and
therefore represents the fluctuating freezing front of the permafrost
table.
Alluvial -Perta·ining to or composed of alluvium or deposited by a
stream or running water.
Alluvial Fan-A low, outspread, relatively flat to gently sloping mass
of loose rock material, shaped like an open fan or a segment of a cone,
deposited by a stream at the place where it issues from a narrow moun-
tain valley upon a plain or broad valley, or where a tributary stream
is near or at its junction with the main stream or whenever a constric-
tion in a valley abruptly ceases or the gradient of the stream suddenly
decreases.
Alluvium - A general term for clay, silt, sand, gravel or similar
unconsolidated detrital material deposited during comparatively recent
geologic time by a stream or other body of running water as a sorted or
semisorted sediment in the bed of the stream or on its flood plain or
delta.
Alpine Glacier -Any glacier in a mountain range except an ice cap or
ice sheet.
Alteration-Any change in the mineralogic composition brought about by
physical or chemical means, especially by the action of hydrothermal
solutions.
Andesite-A dark colored, fine grained extrusive rock that when pro-
phyritic contains phenocrysts composed primarily of plagioclase and one
or more of the mafic minerals (biotite, hornblende, pyroxene) and a
grounamass composed generally of the same minerals as the phenocrysts.
The extrusive equivalent of a diorite.
Annual Frost or Seasonal Frost -Frost which formed in the immediately
previous freezing season and will thaw during the summer thaw season.
By definition, all frost and frozen ground in the active layer.
Aquiclude - A body of relatively impermeable material that is capable
of absorbing water slowly but functions as an upper or 1 ower boundary
of an aquifer and does not transmit ground water rapidly enough to
supply a well or spring.
*Definitions modified from References 2, 13, 24, and 56.
GLOSSARY (Continued)
Aquifer-A body of rock that contains sufficient saturated permeable
materia 1 to conduct groundwater and to yield significantly greater
quantities of groundwater than the adjacent units.
Argillaceous -Pertaining to, largely composed of, or containing clay-
size particles or clay minerals.
Argillite-A compact rock, derived either from mudstone or shale that
has undergone a somewhat higher degree of induration than is present ·in
mudstone or shale but that is less clearly laminated than and without
the fissility of shale, or that lacks the cleavage distinctive of
slate.
Basalt-A dark to medium dark colored, extrusive and intrusive (as
dikes) mafic igneous rock composed chiefly of calcic plagioclase and
pyroxene in a glassy or fine-grained groundmass.
Batholith - A large. generally discordant, plutonic mass that has more
than 40 square miles in surface exposure and is composed predominantly
of medium to coarse grained rocks.
Bedrock-A general term for the rock, usually solid that underlies
soil or other unconsolidated, surficial material.
Bimodal Flow/Slide-A slide that consists of a steep headwall, con-
taining ice or ice-rich sediment, which retreats in a retrogressive
fashion through melting, forming a debris flow, which slides down the
face of the headwall to its base.
Block Slide/Glide - A translational landslide in which the slide mass
remains essentially intact, moving outward and downward as a unit, most
often along a pre-existing plane of weakness, such as bedding, joints
and faults.
Break in Slope-A marked or abrupt change or inflection in a slope or
profile, commonly meant to indicate the transition from steep valley or
gorge walls to more rounded, flatter crest or plateau levels.
Breccia -Fragmented rock whose components are angular; used here to
refer to crushed rock related to shearing.
Carbonate - A mineral compound characterized by a fundamental anionic
structure of C03+, generally refers to calcite.
Cataclastic Rock - A rock cont~ining angular fragments that have been
produced by the crushing and fracturing of pre-existing rock as a
result of mechanical forces in the crust.
tr"~--,
II""'
I
-
-
r-
1
-
,_,
'
-
GLOSSARY (Continued)
Chlorite - A group of greenish, platy minerals, which are associated
with and resemble the micas. Chlorite is widely distributed especially
in low-grade metamorphic rocks, or as alteration products of ferromag-
nesium minerals in igneous rocks.
Colluvium Deposits-A general term applied to any loose, heterogene-
ous, and incoherent mass of soil material or rock fragments deposited
chiefly by masswasting, usually at the base of a steep slope or cliff.
Compressive Strength-The maximum uniaxial compressive stress that can
be applied to a material, under given' conditions, before failure
occurs.
Country Rock -The rock intruded by and surrounding an igneous i ntru-
s ion.
Cr,ystalline-Said of a rock consisting wholly of crystals or fragments
of mineral crystals; especially so in an igneous rock developed through
cooling from a molten state and containing no glass.
Dacite - A fine-grained extrusive rock with the same general composi-
tion as a quartz diorite or granodiorite.
Degrading Permafrost Zone - A decrease in thickness and/or aeri a 1
extent of permafrost because of natural or artificial causes as a
result of climatic warming and/or change of terrain conditions such as
disturbance or removal of an insulating vegetation layer by fire or
human means.
Depth of Zero Annual Amplitude -The depth at which the annual effect
of surface temperatures is not detectable. Be 1 ow the depth of zero
annual amplitude, the ground temperature changes only as a result of
sustained thermal influences on the average ground or surface tempera-
ture, which will elevate or deepen the depth of zero annual amplitude.
Diabase -An intrusive rock whose main components are calcic plagio-
clase (labradorite) feldspar and pyroxene, which is characterized by
lath shaped feldspar crystals.
Dike - A tabular igneous intrusion that cuts across the planar struc-
tures of the surrounding rock.
Diorite-A group of plutonic rocks intermediate in composition between
acidic and basic rocks, characteristically composed of dark colored
amphibole (especially hornblende), plagioclase feldspar, pyroxene and
sometimes a small amount of quartz.
Qi£-The angle that a structural surface, for example, a bedding plane
or joint, makes with the horizontal, measured perpendicular to the
strike of the structure.
GLOSSARY (Continued)
Direct Shear Test-Test measuring the sliding resistance along discon-
tinuities. Usually has two components, friction and cohesion, though
cohesion may or may not be present. A peak angle implying maximum
resistance, and a residual angle depicting the shear strength after
larger shear displacements, are determined.
Drunken Forest - A group of trees leaning in a random orientation; usu-
ally associated with thermokarst topography, reflecting local slope in-
stabi 1 ity.
Dynamic Elastic Properties-Young's Modulus and Poisson's Ratio deter-
mined using acoustic shear and compressional wave velocities of the
material (ASTM 2845-69 (1976)).
Episode-A term used informally and without time implications for a
distinctive and significant event or series of events in the glacial
history of a region, each episode representing a different erosional or
depositional environment.
Esker - A long, low, narrow, sinuous, steep-sided ridge or mound com-
posed of irregularly stratified sand and gravel that was deposited by a
subglacial or englacial stream flowing between ice walls or in an ice
tunnel of a continuous glacier and was left behind when the ice
melted.
Facies Change - A lateral or vertical variation in the lithologic or
paleontologic characteristics of contemporaneous sedimentary deposits.
It is caused by, or reflects, a change in the depositional environ-
ment.
Fault -(see Shear).
Felsic-A general term applied to an igneous rock having light-colored
minerals in its mode. The opposite of mafic.
Flow Structure -The texture of an igneous rock, characterized by a
wavy or swirling pattern in which platy or prismatic minerals are
oriented along planes of lamellar flowage in fine grained and glassy
igneous rocks.
Flows - A broad type of movement that exhibits the characteristics of a
viscous fluid in its downslope motion.
Foliation - A general term for a planar arrangement of textural or
structural features in any type of rock.
Fracture - A general term for any break due to mechanical failure by
stress in a rock. Fracture includes cracks, joints and faults.
Fracture Zone -An area characterized by very close to closely spaced
joints where no measurable relative movement has occurred.
r
.....
-(
r r -
I"""
I
-
r
I
'
1"""'
i
GLOSSARY (Continued)
Geothermal Gradient -The increase of temperature in the earth with
depth. The rate commonly varies from 1 °F /40 feet to 1 °F /300 feet
(1°C/22 meters to 1°C/160 meters) •
Glaciofluvial -Pertaining to the meltwater streams flowing from glac-
ier ice and especially to the deposits and 1 andforms produced by such
streams such as kame terraces and outwash plains.
Gouge -Rock material that has been ground to a uniformly fine particle
size of clay or fine silt sizes.
Grain Size -The general dimensions (average diameter) of the particles
in a sediment or rock or of the grains of a particular mineral that
make up a sediment or rock:
Fine -less than 1 mm
Medium -1mm to 5 mm
Coarse -Greater than 5 mm
Granodiorite-A group of coarse grained plutonic rock intermediate in
composition between quartz diorite and quartz monzonite.
Graywacke -An old rock name that has been variously defined but is now
generally applied to a gray or greenish gray, very hard, tough and
firmly indurated, coarse grained sandstone that has a subconchoi da 1
fracture and consists of poorly sorted and extremely angular to subang-
ular grains of quartz and feldspar with an abundant variety of small,
dark rock and mineral fragments embedded in a compacted, partly meta-
morphosed clayey matrix containing fine-grained micaceous and chloritic
minerals.
Groundmass -The interstitial material of a porphyritic igneous rock;
it is relatively more fine grained than the phenocrysts and may be
glassy or microcrystalline.
Ground Temperature Envelope -An inverted cone-shaped zone i ncl udi ng
the maximum and minimum temperature as a function of depth on a ground
temperature regime plot. Ranges from annual minimum air temperature at
zero depth, showing maximum variation in temperature, to zero annual
variation at the Depth of Zero Annual Amplitude.
Hematite -(see Iron Oxide)
Hydraulic Head -The height of the free surface of a body of water
above a given subsurface point.
Hydrothermal -Of or pertaining to heated water, to the action of
heated water or to the products of the action of heated water used in
relation to hydrothermal alteration of minerals.
GLOSSARY (Continued)
Ice, Massive~ A comprehensive term used to describe large (with dimen-
sions at least 2 to 25 inches) masses of underground ice, including ice
wedges, pingo ice and ice lenses.
Ice, Segregated "'" Ice formed by the migration of pore water to the
freezing p 1 ane where it forms into discrete 1 enses, 1 ayers or seams
ranging in thickness from hairline to greater than 30 feet.
Ice Lens -1. A dominantly horizontal lens-shaped body of ice of any
dimension. 2. Commonly used for 1 ayers of segregated ice that are
parallel to the ground surface. The lenses may range in thickness from
hairline to as much as 30 feet.
Igneous-Rock or mineral that solidified from molten or partly molten
material, that is, from a magma.
Inclusions -A fragment of older rock in an igneous rock to which it
is not genetically related.
Intermontane -Situated between or surrounded by mountains, mountain
ranges, or mountainous regions.
Iron Oxide-A general field term for a group of orange to brown
amorphous naturally occurring hydrous ferric oxides whose actual miner-
alogy was not identified in this study. It is a common secondary
material formed by weathering of iron or iron-bearing minerals.
Isotherm-A line connecting points of equal temperature.
Joint -A surface of actual or potential fracture br parting in a rock
without measureable displacement.
Joint Set-A regional pattern or group of parallel joints.
Joint Spacing -The interval between joints of a particular joint set,
measured on a line perpendicular to the joint planes:
Joint Spacing
Very close
Close
Moderately close
Wide
Very Wide
Interval
<than 2 in.
2 in. to 1 ft.
1 ft. to 3 ft.
3 ft. to 10 ft.
Greater than 10 ft.
Kame - A long, low, steep-sided hill, mound, knob, hummock or short
irregular ridge, composed chiefly of poorly sorted and stratified sand
and gravel deposited by a subglacial stream as an alluvial fah or delta
against or upon the terminal margin of a melting glacier, and generally
aligned parallel to the ice front.
Lacustrine Deposits -Pertaining to, produced by, or formed in a 1ake
or lakes.
p---
-
-
-
-
r
I
!
GLOSSARY (Continued)
Latite-A porphyritic extrusive rock of intermediate composition.
Lithic-A descriptive term applied to rock fragments occurring in a
1 ater formed rock.
Limonite-(See Iron Oxide)
Mafic -Said of an igneous rock having dark-colored minerals in its
mode -opposite of felsic.
Metamorphism -The mineralogical and structural adjustments of solid
rock to physical and chemical conditions which have been imposed at
depth below the surface zones of weathering and cementation, and which
differ from the conditions under which the rocks in question originat-
ed, resulting in visible modifications of the rock properties.
Moraine - A mound, ridge or other distinct accumulation of unsorted,
unstratified glacial drift, predominantly till, deposited chiefly by
direct action of glacial ice in a variety of topographic land forms
that are independent of control by the surface on which the drift
lies.
Multiple Regressive Flow -Forms a series of arcuate concave downslope
ridges as it retains some portion of the prefailure relief.
Multiple Retrogressive Flow/Slide -Series of arcuate blocks concave
towards the toe, that step backwards higher and higher towards the
headwall.
Normal Fault - A fault in which the overlying side appears to have
moved downward relative to the underlying side.
Orogeny -The process of forming mountains, particularly by folding and
thrusting.
Outwash -Stratified detritus, chiefly sand and gravel, removed or
"washed out" from a glacier by meltwater streams and deposited in front
of or beyond the terminal moraine or the margin of an active glacier.
The coarser material is deposited closer to the ice.
Overburden-The soil, silt, sand, gravel, or other material overlying
bedrock, either transported or formed in place.
Pa 1 sa - A round or elongated hi 11 ock or mound, maximum height about 30
feet, composed of a peat layer overlying mineral soil. It has a peren-
ially frozen core that extends from within the covering peat layer·
downward into or toward the underlying mineral soil.
Patterned Ground - A general term for any ground surface of surficial
soil materials exhibiting a discernible, more or less ordered and sym-
metrical, microphysiographic pattern. Used in this report as descrip-
tive of frost wedge patterning.
GLOSSARY (Continued)
Perched Ground Water -Unconfined ground water separate from an under-
lying main body of groundwater by an unsaturated zone with very 1 ow
permeability.
Perched Water Tab 1 e -The water surface of a body of perched ground
water.
Permafrost -The therma 1 condition in soil or rock of temperatures
below 32°F (0°C) persisting over at least two consecutive winters and
the intervening summer; moisture in the form of water and ground ice
may or may not be present. Earth materials in this thermal condition
may be described as perenially frozen irrespective of their water and
ice content.
Permafrost, Continuous -Permafrost occurring everywhere beneath the
exposed land surface throughout a geographic regional zone, with the
exception of widely scattered sites (such as newly deposited unconsoli-
dated sediments) where the climate has just begun to impose its influ-
ence on the ground thermal regime and will cause the formation of con-
tinuous permafrost.
Permafrost, Discontinuous -Permafrost occurring in some areas beneath
the ground surface throughout a geographic regional zone where other
areas are free of permafrost.
Permeability -The property or capacity of a porous rock, sediment, or
soil for transmitting a fluid without impairment of the structure of
the medium.
Phenocrysts -The relatively large crystals which are found set in a
finer-grained groundmass.
Phyllite -An argillaceous rock commonly formed by regional metamor-
phism and intermediate in metamorphic grade between slate and mica
schist. Minute crystals of mica and chlorite impart a silky sheen to
the surfaces of cleavage.
Piedmont Glacier - A thick continuous sheet of ice at the base of a
mountain range, resting on land, formed by the spreading out and
coalescing of valley glaciers from the higher elevations of the moun-
tains.
Pluton -An igneous intrusion.
Plutonic Rock -An igneous rock formed at considerable depth by crys-
tallization of magma or by chemical alteration.
Point Load Test-A test indirectly measuring compressive strength by
loading samples diametrical1y, measuring the splitting load and
converting that to compressive strength.
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GLOSSARY (Continued)
Polygonal Ground - A type of patterned ground consisting of a closed
roughly equidimensional figure bounded by several sides, commonly more
or less straight but some or all of which may be irregularly curved. A
polygon may be either "low center" or "high center" depending on
whether its center is lower or higher than its margins.
Porphyry -An igneous rock of any composition that contains conspicuous
phenocrysts in a fine-grained groundmass.
Porphyroblast-The larger more or less euhedral crystals formed in
metamorphic rocks which have grown during the process of metamorphism.
Proglacial -Immediately in front of or just beyond the outer limits of
a glacier or ice sheet, generally at or near its lower end; said of
lakes, streams, deposits and other features produced by or derived from
the glacier ice.
Relict-Said of a topographic feature that remains after other parts
of the feature have been removed or have disappeared.
Reverse Fault - A fault in which the overlying side appears to have
moved upward relative to the underlying side.
Rhyolite-A group of extrusive igneous rocks generally porphyritic and
exhibiting flow texture; the extrusive equivalent of a granite.
RQD (Rock Quality Designation) -A modified form of recording rock core
recovery. The RQD is the ratio of the total length of core pieces, 4
inches and larger, to the length of the coring run actually drilled.
RQD is expressed in percent.
Rotational Slide-A landslide in which shearing takes place on a well
defined, curved shear surface, concave upward in cross-section, produc-
ing a backward rotation head of the in the displaced mass.
Seismic Refraction -A type of seismic exploration based on the mea-
surement of seismic energy as a function of time after the shot, or
initial energy impulse, and of the distance from the shot, by determin-
ing the arrival time of seismic waves which have traveled through over-
burden and/or bedrock in order to map 1 ayers in the over bur den and the
top of the bedrock surface.
Seismic Velocity -The rate of propagation of an elastic wave, measured
in feet per second. The wave velocity depends upon the type of wave,
as well as the elastic properties and density of the earth material
through which it travels.
Shear - A surface or zone of rock fracture along which there has been
measurable displacement.
GLOSSARY (Continued)
Shear Strength-A material 1 S resistance to shear failure~ Intact mat-
erials possess both cohesive and frictional resistance. Discontinui-
ties have frictional resistance but may or may not have cohesive resis-
tance~ Frictional resistance of discontinuities may have two compon-
ents, one depicting planar surface sliding resistance a_nd the other
depicting surface roughness.
Skin Flow-The detachment of a thin veneer of vegetation and m·ineral
soil with subsequent movement over a planar inclined surface, usually
indicative of thawing, fine-grained overburden over permafrost.
Slickenside-A polished and smoothly striated surface that results
from friction along a fault/shear plane.
Slides-Landslides exhibiting a more coherent displacement; a greater
appearance of rigid body motion.
Solifluction Flm'l-Ground movements restricted to the active layer and
generally requires fine-grained soi 1 s caused by melting of saturated
soils.
Static Elastic Properties-Young 1 s Modulus and Poisson 1 S Ratio measur-
ed during unconfined compression tests (ASTM D 3148-80).
Strata-Plural of stratum.
Stratigraphic Column - A composite diagram that shows in a single
column the subdivisions of part or all of the sequence of stratigraphic
units of a given locality or region so arranged as to indicate their
relations to the subdivisions of geologic time and their relative posi-
tions to each other.
Stratigraphy -The arrangement of strata, especially as to geographic
position and chronologie order of sequence.
Stratum-A tabular or sheet-like mass or a single and distinct layer,
of homogeneous or gradational sedimentary material (consolidated rock
or unconsolidated earth) of any thickness, visually separable from
other layers above and below by a discrete change in the character of
the material deposited or by a sharp physical break in deposition, or
by both.
Strike -The direction or trend that a structural surface, for example,
a bedding or fault plane, describes as it intersects the horizontal.
Strike Slip Fault-A fault, the actual movement of which is parallel
to the strike of the fault.
Talus-Rock fragments of any size or shape (usually coarse and angu-
lar) derived from and lying at the base of a cliff or very steep, rocky
slope.
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G~OS$ARY (Continued)
Tensile Hrength ,. The maximum qppl i~d te.m§ih l)tr~~~ th9t a body ccw
withst'aii!:f'&~fgre f9il ure (.H~c:urs.
Terrace "' Any lgn~, fli:H'1 FPW~ relatively level or ~~nt1y in~;;lin@d sur,.
fac~, gen!l!r<:~lly le$S bro9c:l thM a Ph1n, bounde,d ·plong on~ ed~~ by ~
steeper de~cending !5lope ill!d 91ong the other by c:~ s.t~H~per IHHJendin9
s 1 ope.
Terrace Deposits "" A general term Y!fied to desqribe glluvia1 benGhe!\1
along the slde ·of a ~rtream or river V911ey, which are no hmger within
the norma 1 fl oodp hi n of the bodY of water. Usect in contra~t to a<:t i ve
river alluvil)m, within the pre!:II1Jnt c;;ha·nnel, and flood plain depgsits
which lie within the C\Jrrent hydrologic re~ime, but outside gf iHWIJal
f1 ood limit&.
Thalweg ,., The line c:onn,ecting the h>.west or c:!eePe~t ppints alons a
stre~rri bed or valley, whether under water or not, Applied in thi~
report to include the lowest point of flow in a potential aquifer,
Th~rmistor "' A thermally s.~nsitiva resi§tor employing C! s!;lmicondt,Jctor
Wfth a large negative resistance .. temperature coefficient~ used as an
electrical thermometer~
Thrust Fault "' A reverse f(lt,!lt with Ci dip of 45 9 or less. Hori;;!ontal
compression rather th~W vertical disPlCicement is its charC!cteristic
feature.
Till ~ Unsorted C!nd unstratified drift, generallY unconsolidated.
deposited directly by and underneath a glacier without subsequent
reworking by water from th@ gl aci !iW and c.ons isti ng of a hetergg~nequs
mixture of clC!Y, sC~nd, gravel P.nd boulders varying widely in si?e iHJd
shap~. · ·
Tundrei ~ A treeless, generally level to undulating region of lichens.
m!J~ses, sedges, gNsses. and some low shruhs, including dwilrf willpws
and birches, which i!ii charCicteriHic of both the Ar¢tio and higher
eilpine regions outside of the Arctic. ·
Wnit Weight "' A term P.PPlied, especiellY in soil mechanic:s~, to the
weight p¢'r unit vo 1 ume,
Varvfii "' A sed imenti!rY becl or 1 grni na or sequen~;e of hmi nae depo!;lited in
~(body of still water within one yegrts time~ S.PecificCillY a thin Pilir
of gNded glaciolC~C'~strine layers fl,eas~HH11lY f:lep~;>sited (usually PY
meltwater streams) in iii glacial lilke or 9ther bodY of still water in
front of a glacier, · M
Volc;anic Rock ~ A generallY finely crystC~lline or ~la§sy i~n~ou$ rook
rest4ltihg from vglt;;iH11G 9ction 11t or nea.r th-(a e9rth 1 ~ ~yrht;:~~ ~ith-eP
!9jected ~J~~plo~ivel,y ~r ~Hft;tl'yged ~~ lavii, Th~ term inG1~J9tl~ nt:H1r~~~tJr ..
faca intr\llioni that farm a. pirt of the volcinie &tructure~
GLOSSARY (Continued)
Weathering -The destructive process or group of processes constituting
that point of erosion whereby earthy and rocky materials on exposure to
atmospheric agents at or near the earth's surface are changed in char-
acter (color, texture, composition, firmness or form). with little or
no transport of the loosened or changed material.
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REFERENCES
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2. American Geological Institute, Glossary of Geology, Kingsport
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5. Billings, M. P., Structural Geology, Prentice-Hall Inc., New
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15. Deere, D. U., Hendron, A. J., Jr., Patton, F. D., and Cording, E.
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17. Deere, D. U., Monsees, J. E., Peck, R. B., and Schmidt, B., Design
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18. Detterman, R. L., Plafker, G., Hudson, T., Tysdal, R. G., and
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19. Ferrians, 0. J., Jr., "Permafrost Map of Alaska", U.S. Geological
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21. Hendron, A. J., Jr., "Mechanical Properties of Rock", in,Stagg, K.
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REFERENCES (Continued)
25. Jones, D. L., and Silberling, N.J., "Mesozoic Stratigraphy, the
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27 0
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29.
30.
31.
U. s. Geological Survey, Professional Paper 1121-A, 1978.
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Karlstrom, T. N. V., "Quaternary Geology of the Kenai Lowland and
Glacial History of the Cook Inlet Region, Alaska 11
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Geological Survey, Professional Paper 443, 1964.
McRoberts, E. C., and Morgenstern, N.R., "The Stability of Thawing
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37. R & M Consultants, Watana Climate Data, September, 1980 through
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REFERENCES (Continued)
38. Richter, D. H. and Jones, D. L., "The Structure and Stratigraphy
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41. Smith, T. E., Bundtsen, T.K., and Trible, T. C.,
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"Stratabound
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Geophysical
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45. u.s. Army Corps of Engineers, Hydroelectric Power and Related
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46. u.s. Army Corps of Engineers, Petro ra hie Examination of Led e
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48. U.S. Army Corps of Engineers, Susitna Pro·ect, Re ort of Tests on
NX Rock Cores for Ta 1 keetna and Watana Sources 78-C-305 ,
North Pacific Division Materials Laboratory, Troutdale, Ore-
gon, 1978.
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REFERENCES (Continued)
49. u.s. Ar~ Corps of Engineers, Report of Tests on NX Rock Cores and
Ledge Rock, Talkeetna Flood Control Project, North Pacific
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53. u.s. Bureau of Reclamation, "Laboratory Tests of Foundation Rock
Cores from Devil Canyon Damsite, Devil Canyon Project -
Alaska", Concrete Laboratory Report C-933, 1960.
54. Van Eysinga, F.W.B., Geologic Time Table, 3rd Edition, Elsevier
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55. Varnes, D. J., "Landslide Types and Processes", in, Eckert, E.B.,
(ed.), Landslides and Engineering Practice,Highway Reserve
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