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SUSITNA HYDROELECTRIC PROJECT
1982-84 GEOTECHNICAL PROGRAM
SUBTASK 5.07 REPORT
Prepared by:
....____ __ ALASKA POWER AUl-HORITY __ ____,
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ALASKA POWER AUTHORITY
SUSITNA HYDROELECTRIC P~OJECT
DESIGN LEVEL GEOTECHNICAL INVESTIGATIONS PROGRAM
TABLE OF·-CONTENTS
LIST OF TABLES
LIST OF FIGURES
1 GEOTECHNICAL INVESTIGATIONS PROGKAI4 GOALS • • • • • ~ ~ e, • • • 4 • • e • • •
1.1 -Design Level Prvgram Go<,ls ···9·*···························
(a) Program Philosophy t ........... ~ ............ ~·······!'., ........ ..
(b) Pata Uses •••••••••••••••a••••·························
(c) Previous Explorations ·····························ft···
(d) Constraints ··~••••••••••••••••••··~····.,······~·a•••••
1.2-Investigative Procedures ·················~·················
(a) Investigative Methodology .; ........................... .
{b) Methods of Exploration ••••••••••••••••••••••••••••••••
(c) Data Reduction and Compilation ••••••••••••••••••••••••
2 DESIGN LEVEL GEOTECHNICAL ••••••••••••••••••••••••••••••••••
2 .. 1 -Program Development ............................... o•••••••••••
2.2-Design Level Geotechnical Investigations-Watana ••••••••••••
(a) Damsite -Abutments and Underground •••••o•••••o•••••··
(b)
(c)
(d)
(e)
(f)
(g)
(h)
Damsite-River Area o ................... o .............. .
Relict Channels ...................................... ~) •••
Impervious Borrow······················~··············
Granular Borrow ....................................... .
Rock Quarry ............................................... .
Reservoir ·······~······ .. •••••••••••••••••·•···········
Aux i 1 i ary Fa c i 1 it i es ...................... ,, ............ .
3 DESIGN LEVEL GEOTECHNICAL INVESTIGATIONS-DEVIL CANYON ••••••
3. 1 -Progratn Deve 1 opnent ......................... .., ............... .
3.2 -Design Level Geotechnical Investtgations-Devil Canyon ...... .
(a) Oarnsite-Abutments and Underground ................... .
(b)
(c)
(d)
(e)
(f)
(g)
(h)
Ua1nsite -River Area ......................... o •••••••••
Re1ict Channels ••••• ~ ................................... .
Impervious Borrow Sources ........... "•••••o•••·········
Granular Fill L~d Aggregate Sources •••••••••••••••••••
Rock Quarry Site.s •••••••••• o •••••••••• o •• ,. ............ .
R e s er v o i r • • • • • • • • • • • • • • • o • • • • • • • .. • • • • • • • • • • • • • • • .. • • • ••
Auxiliary Facilities ~·································
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TABLE OF CONTENTS (Contta)
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4.1
4.2
5
5.1
5.2
ACCESS ROUTES ••••••••••••••••••••••••••••••••. , •••••••••••••
Program Deve 1 oprnent ........................... &' •••••••••••••
Program Scope
• • • • a • • e • • • • o • • • • • • • • • • • • e o • • • • • e ~ • • • • • • • • • s • • (a) Route Aligrnnent
{b) Bridge Locations • • • • • • a ~ e • • • • • • • • • • • ~ • • • • • • a • • • ~ • • o ~ o • •
(c) Slope/Cut Stability and Hazard Analysis ••••••••• , ••••••
(j) Subgrade Conditions
o • • • a e • • • • • • • • • • • • • a o • • o c • • • ~ ·•· • • • o • • • •
• • • • • • • e • • a • • • • • • • • ~ • • ~ • • • • e • • o 0 • • • (1.~) Borrow Materials········~·····························
• • Q • • • c • • • • • • • 8 • • • • ·• • • • • • • • • • • • • ~ • • • • • • • • • •. • • • • TRANS"'U SS I ON
Program Deve l Ot)nent • • 0 0 • • • • • • • • • • 0 • 8 • • • • • • 0 • • • • • • • •. • • • • • • • •
Program Scope ••••••••••••••••••••••••••••••••••••••••••••••
(a) Route Alignment ·············••••c•• , ................. (;.
(b) Major Crossings
(c) Hazard Analysis
(d) Tower Foundation.
• • • • • • • • • • e • • • • • • ~ • • o • • • • • • • e • • o • • e • a • e
• • • o • e • • • • c • o G • • • • • • • • • • • • ~ e ~ • • • e o a • • • •
• e • • • • • • • • • • • • • e • • e • o • e • • • • • • • a • o • • • • (e) Substations/Switchyards ••••••••••••••••••••••••••••••••
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LIST OF TABLES
TABLE TITLE
1.1 Exploration Methods
1.2 Detailed Exploration Method Breakdown
1.3 Specific Field and Laboratory Tests
1.4 Correlation Matrix of Potential Relationships
1.5 Geotechnical Interpretation Working Media
1.6 Investigati~e Procedure -Scope Presentation Format
2.1 Watana Damsite -Geotechnical Parameters
2.2 Watana D,amsite -Geotechnical Exploration Recorrmendations
2. 3 ~Jatana Re 1 ated Areas -Geotechni ca 1 Parameters
2.4 Watana Related Areas -Geotechnical Exploration Recommendations
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LIST OF FIGURES
FIGURE TITLE
1~1 Schematic of Phases of Geotechnical Investigations
1.2 Geotechnical Program Fermat -Watana
1.3 1982-85 Proposed Geotechnical Investigation Program
l.A Exploraticns Pr,..~ram Development
1.5 Systematic Prv~edure for Explorations and Data Interpretation
1.6 Data Reduction and Compilation Procedure
2 .. 1 \~at ana ;.. General Arrangement
2.2 hatana Camsite -Geclc£iC Map
~.3 Watana -Ecrrow Site Map
3.1 Devil Canyon -General Arrailyement
Oevi 1 Canyon -Geologic f ... lap
Devil Canyon -Geologic Section DC-3
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1 -GEOTECHNICAL INVESTIGATI~NS PROGRAM GOALS
~~--------------------~---------------
1.1 -Design Level Program Goals
(a) Program Philosophy
The preparation of a geotechnical investigation program on the design level
is set forth as subtask 5.07 under the Plan of Study for the Susitna Hydro-
electric Project. The stated scope is to accomplish:
10 Design of the geotechnical exploratory investigations program for
1982·-1984 to obtain basic design data for Watana damsite, dam
construction materials and reservoir area, and for the selected
acces: road and transmission 1 i ne routes. 11
In order to accomplish this scoping task, an integrated look at total de-
sign data requirements was necessary. The work scoped as the 1982-84 act-
ivities represents the total design level geotechnical data collection pro-
gram up to award of contracts for construction, but does r.ut include such
-items as test fills, excavation stability monitoring, and pre-production
placement condition testing; which properly falls under construction moni-
toring and design parameters verification costs. For this reason, the pro-
gram outlined below has been designated the Design Level Geotechnical
Investigations Program to distinguish it from the other various phases of
investigations (Figure 1.1).
The schedule of geotechnical activities has been based on the preliminary
engineering design and construction schedule presented in Plate 16 of the
Fe~sibi~ity Report Summary, March, 1982. Changes in this schedule may have.
a major impact on geotechnical activities. Similarly, the program pre-
sented in this report assumes that overland access will be restricted dur-
ing 1982-84; :~hereby limiting the type of. equipment to be used, as ~:ell as
the field program planning.
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The Design Leve.l Geotechnical Investigations Program has been developed to
expa~~ the feasibil~ty level information into a complete geologic~ rock
mechanics, and physical model of appropriate detail to support deta~led
engineering and design on the Susitna Hydroelectric Project. For simplic-
ity and appropriate distinctior between various aspects of the project, the
program scope has been separated into four distinct and essentially inde-
pendent areas of investigation:
Watana damsite and reservoir;
Devil Canyon damsite and reservoir;
-Access routes; and
-Transmission corridor.
This breakdown is appropriate because it reduces the scope into areas of
activity th~t may be conducted independently. It also represents a logical
separation in p 1 anni ng and supervision both in terms of geographic .l aca 1 e
and of probable phasing of the work to correspond to varying start-of-.
construction dates in the overall project schedule.
(b) Data L!ses
The over a 11 program for design 1 eve 1 investigations wi 11 provide i nforma-
tion for a number of design and planning activities, a representative list
of which is given below:
-General arrangement adjustment;
-Feature design and optimization;
-Construction quantity and cost optimization;
-A·lternative technical factor selection;
Facility design and construction method simplification and value engi-
neering; -.
-Environmental impact assessment and mitigation design; and
-Responding to public inquiry and concern.
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(c) Previous Exploration~
Previous explorations at the Susitna sites are documented or referenced in
the 1980-1981 Geotechni"cal Report. The future investigations will suppie-
m€nt and expand upon this previous work. Previous investigations included
geologic mapping, subsurface exploration in overburden and rock, seismic
surveys, down hole testing, and laboratory testing of rock and soil
samples. The information gathered so far has been sufficient in provi.ng
the feasibility of the project, but further explorations are necessary for
design and construction of the facilities.
(d) Constraints
( i) Schedule .
The investigations wi 11 be split into two stages. Stage I, con-
ducted in Fi seal Year 1983 (July, 1982 -June, 1983), wi 11 enhdnce
understanding and data on general geology of the Watana site.
Details of this program are summarized in this report and further
defined in Fiscal Year 1983 Geotechnical Explor&~ion Programv This
will enable arrangements and layouts to be optimized and confirmed ..
Investigations for final design of the Watana features (Stage II)
wi 11 provide specific design data for structures at specified loca-
tions, data for detailed estimates:; and data for the construction
schedule; as well as providing all the layout and design geotechni-
cal data for those construction items which are not on the critical
design schedule; such as camp facilities, emergency spillway~
switchyard, and site contruction roads. 9ue to the scheduling con-
straints, the two stages will not be distinct but will tend to over-
lap, with t:·te 1982-1983 program providing the basis for layout of
the subsequent explorations in the critical areas as shown on Figure
1 .. 2~
The preliminary schedule is based on a preliminary construction
activities schedule as presented in the Feasibility Report Summary,
and as shown in Figure 1.3.
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(ii) Budget
An inherent constraint with the geotechnical program is budgetary
limitation and the fiscal year basis of funding. Funding for the
project is based on a 12 month fiscal ye.ar ranging from July 1 to
June 30. The fiscal year ends in the middle of the summer fieln
seasons. Therefore, detailed planning and scheduling must be
allowed' for to insure that site activities are not restricted due to
budgetary limitations during the prime good weather month~.
The total budget will have to include all design level geotechn-ical
activities through preparation of bid documents, which might, de-
pending on project schedule, run into FY85 for some activities at
Watana. C~2arly, a large portion of the site access and virtually
a 11 the Devi 1 Cc.~,yon and transmission. design wi 11 be conducted. after
1984 because the schedule does not require this data at an early
date.
(iii) Access and Weather
This investigation program is planned on the assumption that access
roads to the damsite will not be constructed until after the FERC
license is granted, and that over1and mGvement of v~hicles and
equipment is limited to the winter period when the thickness of
frozen ground and snow cover is acceptable to the U.S. Bureau of
Land Management and any other responsible regulatory agency. There-
fore, the program takes into account the restrictions this imposes
on the i nvesti gati on by 1 imi ti ng the type of equipment that can be
used onsites-which will reduce efficiency of onsite geotechnical
work. These restrictions will increase costs due to continual heli-
copter support requirements, increased unproductive time during
drill rig moving, winter work loss of productivity, and limitation
of the program flexibility in locating explorations.
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1.2 -Investigative Procedures
(a) Investigative Methodology
The methodology for the investigation program has been developed with four
primary considerations in mind:
-DATA INTEGRITY, ~o assure accuracy and standardization of i nformat 1 :Jn.
-MAXIMIZATION OF FEATURE DETECTION probability, both of anticipated and
unexpected features with emphasis on collection of fully descriptive data
at· ~ach si gnifi t.J.nt feature.
-PROGRAM FLEXIBILITY, to increase or decrease committment to a particular
teature based an the ongoin~ interpretation effort.
-FISCAL CREDIBILITY, both in t.erms of data received for do 11 ars spent 1 n
investigations~ and in terms of dollars spent in the investigations as
compared to the sensitivity of the project schedule or construction cost
to potential variability in the geotechnical condition explored.
These considerations are discussed in the fo 11 owing sections and are re-
flected in the explorations methodology shown in simplified form on the
Explorations Program Development schematic (Figure 1.4).
( i) DATA INTEGRITY -The criteria of ensuring accuracy and standard i-
zat ion of information introduces sever a 1 equipment and support re-
quirements. The basic primary approach to this criteria is use of
a detailed field procedures manual and specific forms to guide the
data collection activities. Other standardization will be insti-
tuted in th~ following areas:
-Utilization of current nationally accepted standards of testing
and measurements, both to facilitate understanding of there-
su 1 ts and to ensure uni forr11i ty of sampling and testing proced-
ures, and thereby, site-wide comparability of results.
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-Use of adequate samp 1 i ng and testing methods that wi 11 accur-
ately define site geotechnical conditions, with particular
attention to effect of sample size on data results.
-Training of field personnel to ensure conformity of field pro-
cedures and data collection.
-Standardization of reporting format and forms to serve as a
guideline to data collection.
Adequate amounts of testing to provide a valid data base for
analysis of expected variability of in-situ conditions, and to
provide a data base against ~hich individual results can be
tested to detect anomalous results, results which have been in-
advertantly int1uded in the wrong data set, or that are a result
of errors in field sampling procedure.
( i i) The MAXIMUM OF FEATURE DETECTION methods involves use of a variety
of data collection and reduction means ranging from visual obser-
vation through precise field and 1 aboratory instrumentation. The
various means of in\estigation \"lhich may be used are described in
Section 1.2(b)9 broken down into four general classes by level of
sophistication (Figure 1.5). Basically, the Reconnaissance and
Primary means h?.ve been utilized in prior investigations at the
sites, and wil) be used throughout the continuing program to eval-
uate areas not covered in the pre-design level work and to obtain
additional data density in the existing work areas. The Advanced
Explorations can provide more representative data, data from loca-
tions where Primary exploration is prohibitively expensive or does
not provide adequate information, and to detect properties of
materials which can only be measured through use of more sophisti-
cated means and equipment. The Special Techniques include sophis-
ticated and highly specialized means that can provide the desired
information wher·e other methods f ai 1. The Speci a 1 Techniques, in
many instances, may not be required at a 11 on the project. This
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(iii}
systematic procedure of data collection, ty combining progres-
sively more advanced explorations with concurrent data reduction,
will increase the efficiency of the exploration and interpretation
activities.
The development of PROGRAM FLEXIBILITY requires procedures for
program planning and field operations which minimize the chances
of failing to observe or sample significant features, without com-
mitting resources in excess of those necessary to obtain the re-
quired information. The basis for this goal is sequential devel-
opment of the interpretation model utilizing the results of the
existing data at each phase. Continuing effort will be made to
assess the potential of additional data collection efforts,
detecting additional features or obtaining the more detailed and
precise i nform,at ion needed 1 n design.
The combination of phased explorations, utilizing increasingly
sophisticated methods in each subsequent phase, a11ows checkpoint
review of the exploration effort being expended versus the infor-
mation being obtained •. In most instances, preliminary contact
with a specific feature or material has been achieved in Recon-·
naissance or Primary stage explorations, and based on the results
of that work the proper level of investigation can be determined
at this time for production of design level data.
For optimiz.ation of the overall exploration and geotechnical de-
sign program, a large degree of flexibility in field equipment and
schedule is desirable, and with the magnitude of program required
on this size project~ the adaptability and flexibility of the pri-
mary exploration equipment may be increased by three primary pro-
cedures:
-Selection of versatile equipment;
-Augmentation with additional resources and specialized tools and
equipment; and
-Onsite availability of a diverse selection of equipment.
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By having diverse and versatile equipment onsite and supplementing
this with signif~cant backup and support tools and facilities~ the
1 arge-scale program wi 11 inherently have the physical flexibility
' to adapt to unexpected conditions that may be encountered. The
field supervision will then operate under the program procedure to
adapt to ~arious conditions through the following options: -
-Modification of data cullection method;
-Selection of alternative ~~quipment;
-Repositioning of exploration sites; and
-Selection of a different level of sophistication.
(iv) The FISCAL CREDIBILITY of the explorations programs is being
incorporated through four basic means, all of which are based on
the utilization of composite data reduction with a methodology to
maintain all field data compilations up to date with the explora-
tion program progress, as outlined in Section 1.2(c). The four
means of control in the planning are:
-Use of the progressive levels of exploration sophistication to
utilize only as complex and expensive a method as is called for
tn obtain the desired information.
Use of a staged exploration scheme which will utilize the simp-
ler and, therefore, less experisive methods for initial target
definition, thereby saving the detailed methods of investiga-
tion for areas that have been definitively located and deter-
mined to be critical. Ideally, each stage of exploration will
progress concurrent with the design stages to provide the level
of information that is consistent with requirements for design
criteria.
Combination of detailed and general investigations to provide
very specific information at critica1 control points, with less
s~tlfic confirmatory data to fill out intervals between the
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detailed data points and to provide basis for extrapolation
while still maintaining confidence in the final model.
-Assessment of the sensitivity of project schedule or cost to the
geotechnical data on any sp~::::ific feature, with the intent of
weighting the exploration expenditures in favor of those fea-
tures or considerations which have the greatest potential im-
pact. A detailed risk analysis or least-cost sensitivity matrix
·analysis would not be justified, either on the basis of the man-
hours it would take to develop and monitor, or considering the
complexity and diversity of geotechnical conditions. However, a
subjective and estimate"level objective ass~ssment of construc-
tion sensitivity to various parameters will be utilized to
assess the merits of additional or more sophisticated studies.
(b) Methods of Exploration
The d1ver~ity of exploration methods that can be used to obtain geotech-
nical data is limited only by the cost effectiveness of the systems. Be-
cause of the wide range of conditions and factors being investigated on the
project sites, this section will present a summary of the various m~thods,
their uses!> and the app 1 i cabi 1 i ty of the methods, in genera 1, to the proj-
ect. The specific design feature scope statements will be presented in
subsequent section as ~ set of summary sheets showing which methods of ex-
ploration are anticipated for use on each feature.
As discussed in Section 1.2(a), (i), and (ii), the geotechnical program has
been planned on the basis of four general levels of sophistication in data
collection, and use of standardized testing and samp~ing procedures. The
levels of exploration studies at~e:
Reconnaissance Level studies which serve to give an overview of work re-
quirements and the best techniques to be used for obtaining the desired
information. They also serve as the basis for locating most Primary
Investigations.
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-Primary Investigations, which includes most of the traditional mear1s of
drilling and geologic mapping, and includes routine 11 disturbed" sampling ..
and testing, and labot'atory testing usually associated with routine geo-
technical design.
-Advanced Explorations include the sophisticated down hole and laboratory
testing techt!liques, "undisturbedu sampling, in-place testing methodsf and
the speciali2;ed drilling and sampling techniques for penetration of zones
which cannot be routinely sampled~ or in which normal 11 primary
11
sampling
methods are not effective. These methods also include the more sophisti-
cated, yet ·::ommonly available remote sensing and profiling methods for
surface detection of subsurface conditions.
-The Special Techniques include those methods or equipment which are
either prohibitively expensive or too time consuming for conventional
use, but produce the detailed or sophisticated information needed for a
detailed understanding of conditions, and are used on features or
materials which are critical in development-of design criteria or design
solutions,
Each of the different generic types of exploration activity can be broken
down into this expanded level of sophistication system (Table 1.1). The
generic types of activity to be utilized are determined through use of the
systematic exploration program development methodology (Figure 1.4) and can
include any of the vai-ious detailed techniques and variations shown on
Table 1.2. These specific and trade-name techniques can be combined into
generic subsets, each of which includes a set of specific applications
which introduce similar levels of sophistication or expense. By assessing
the potential significance of the geotechnical feature being exp·lored!l one
co.n use the risk reduction or potentia 1 savings from avai 1 abi 1 ity of the
data to define the, level of sophistication (and~ consequently 5 tne explora-
tion cost) which is appropriate to that feature.
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(c) Data Reduction and Compilation
Data reduc-tion and campi latior 1 s the single most crit.ical activity in-
volving office and field staff coordination because unless the data is r~ ...
duced, compiled, and summarized properly, the significance and validity of
$)
the field data can easily be lost or misrepres~nted. This common problem
can be minimized through use of comprehensive data collection forms that
e 1 imi nate the need for office 11 i nterpretation" of the data i tse 1 f. Use of
such forms and record keeping procedures places the total responsibility of
accurate data taking wit~i the field or laboratory personnel, so the office
personne 1 can then concentrate on defining data re 1 at i onshi ps and corre 1 a-
t ions which will extend the understanding 1f th~ geologic model. There-
fore, the data collection procedures will be conducted in accordance with
the applicable procedure manual or $tandardized test procedure, and the
flow of information and ched~ procedures wi 11 be in accordance with the
flow diagram.on Figure 1.6 .
The field sampling and laboratory testing procedures will be conducted, to
the greatest extent possible, in accordance with the American Society for
Testing and Materials (ASTM) annual books of standards.
"
Where ASTM standards or guidelines are-not available or adequate, the fol-
lowing organizational standards or procedure manuals will be applied:
(i) American Association of State Hi~hway and Transportation Officials
(AASHTO).
(ii) U.S .. Army Corps of Engineers, Office of Chief of Engineers (COE)
Design Guides, Engineering Manuals, and Standard Specifications.
(iii) U.S. Bureau of Reclamation (USBR) Design Standards and Engineering
Monograph Guidelines.
(iv) U.S,. Bureau of Land Management (BLM) Techr1ical Bulletin Guidelines
and Procedures (alluvial and placer deposit sampling and reserve
calculat~ons).
0
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(v) U.S. Bureau of Mines (USBM) testing procedures and reserve calc~la
tion methods.
The particular parameters which may be tested are presented in Table 1.3~
Each feature or project aspect (Sections 2-5) also references summary
tables of anticipated testing, broken out by purpose and applications.
(d) Interpretation and Reporting
The interpretati0n and reporting procedures from the crux of the design
parameter definition process. Since the level of geotechnical effort to
accurately define the geotechnical subsurface conditions at the site is un--
known, the interpretive technique(s) that can best be applied cannot be
clearly specified at this time. Therefore, only a guideline list of pos-
sible correlations can .be developed, with the intent of investigating the
.. lidity of these potential correlations, as the detailed data is received.
A partial matrix of possible relationships that may apply at a particuliir
feature or arec.. is presented on Tab1e 1.4. Adherence of the data to any of
these relationships will be tested statistically in the final interpreta-
~ion,_with initial apparent relationships being developed from the field
and office working media shown on Table 1.5. In many instances, correla-
tions may appear by coincidence due to the local condition~ but would net
be expected to prev ai 1 site-wide, whi 1 e ot~1er corre 1 ati·ons \<lhi ch might be
expected may not appear in the analysis due to local site variability,
erosional history, or ather transient influences. In most cases, the cor-
re1;tion matrix method will be used to point out relationships of apparent
significance which might merit further interpretatiOli or investigation,
• rathet" than to form a primary basis of conclusions.
Report presentation will emphasize the pertinent relationships derived in
the interpretive process, with the majority of the data being prepared in
graphical or tabular format. Emphasis wi 11 then be placed on descriptive
text utilizing extensive cross-referencing to the location figures, tables,
and correlation graphs used to develop the interpretation.
1-12
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TABLE 1.1: EXPLORATION ~lfTHODS
CtvEC OF 50PHlslttATTO~mN~----------------------------------------~------------------------------
~----------------------------~-------------------------,,-·------~------~~~------~~~~~~------~----------------------++------------------------------------
SPECIAL ~OTES
--~GE;;.:N.:.:~E:.;:;R:.::.I;::.C ...:.A.;.;:C..;..T;::.l V.:..:I.:..:T..;..Y ___ +-____ :..;.;RE:;.;C;.:;;O.;.;;..NNA ISSANCE
SURFACE & SAI:PLII\G:
GeoloQlC l<lapp1no
Remote Sensmg of Sr,rface
features
Remote Sensmg for Evidence
of Subsurface Feaf.ures
Feature Location Surveys
Borehole/Explorations
locat 1on Surveys
P.ydrographic/R1ver Cros·;
Section Surveys
Quarry Material Location
Borrow Material Locat1on
SUBSURFACE:
Stratigraphy, Bedrock
Location
Rock Qualitv Determjnation
-Shallow
-At Deplh
Damsite & Quar:-rv Sampl1ng
-Shallow ·
-At Deplh
Overburden & Sorrow Hater1al
Sampling
-Shallow
_. At Oct~th
Borrow ~1ater1al Extent 1
Qu~=Jlity at Depth
Aena1 overfliohts or spot fteld
\"Jali<-over, <H r photo Interpret a-
tat wn.
ttncontrolled au· photo mosaic
evaluatJon.
Standard 9 x 9" air photos -
color or black and white, map
l1neament stud1es.
Field-pick on air photos or USGS
1 inth = 1 mile maps.
F1eld-spol on a1r photos or topo-
graphic maps.
Scale from air photos and maps.
Geologic mapping air photo inter-
prelat ion.
Geologic mapping a1r photo inter-
pretation.
Outcrop mapptng, probe holes.
Surface outcrop sampling.
Inferred from surface qeologic
mapping •
Outcrop sample collection.
Inferred from surface mapp:ing.
E.xposure sampling.
Inferred from surface mapping.
Inferred from geolJg1c mapping,
mterpretation.
* See .instrU'llenlat!on and i: est mq Interpret a~ ion.
PRIHARY
Air photo 1nterpretat1n~, ard \ape
and brunton traverses.
Cant rolled air photo study, tJ•ansfer
lo base map by air photo int-erpre-
t at ion methods.
ERTS Satellit.er SLAR, low-level
photography, thermal thf"matic
mapping.
Air photo panel or tape and Brunton,
compass resect ion.
Stadia/intersection survey; tape and
Brunton, air photo panel 1Dcat.ion.
Field survey by soundings.
Hand dug samplest face exposure
channel samples.
Hand du9 test pits and channel
samples.
Seismic, resistivltyr drilling, te.at
pits or trenches~
Cere drilling, pr~be holes WJth
bottom grab samplest seismic methods
Rock corjnq, drill hole loqqing.
Surface gPophysicsJ percussion probe
holes.
Rt-i.a·y core bonng.
Auger sampling, test pHUng.
Auger or small diameter rotary
bormgs.
Surface geophyics, probe borJngs.
ADVANCED
Survev controlled detatl feature
mapp1;:.0 and photography.
Satell1te lmagery, airborne
radar, 1nfrared photography.
Prof1ling radar, non-vi3ible
band 1magery -airborne or ERTS.
Survev instrument~ stadia/
resecEion survey.·
Full t ranstl or EDH survey.
Se1sm1c sonar profJling.
Test blasts, laboratory tests.
Bulk sampling-test trenches.
Shafts, adits, large-diaflleler
borings~
Shan, test. trench or large
diameter boring, geophysics.
Down hole camera, geophysical
logqinq, dmmhole rock mechantcs
inslrllilentalion.
Test trenches.
Pattern core bor.mg.
Larqe test trenches.
Bucket auger, larqe reverse
circulation borings, down hole>
geophysics.
Larqe diameter borinqs, larqe
test pits.
Te-lt>pholo nosaic, fu11 surveyer.
grid system, laraP-ocale mapr1nq.
Advanced satellite, low-level
mull 1-spec1al scanning; low-level
tow:~d auborne detectors.
Surface radar, maqnetor'leter,
gravimeter.
Grid control survey with large-
scale mapp:ang.
Theodolite/hiqh precision EDM
survey; auto-surveyor.
Sonar/rad1omet ric grid or blanvet
surv~ys.
Svstematic geochemicdl, media
separation JTlethod sampling.
Systematic geochewlcal, media
separation method tlarr:pling.
Radar, ~nwn hole g~ophysics.
Down holn rock m!:'chanics instru-
mE>ntation, advanced borehole
geophys1cs.
Dowr. hole logginq* and instrunen-
tat ion, acilts and shaft-s, :in-situ
testing.
Trial blast.
Trial blast, large diameter bored
shafts or calyx holes.
Trial excavation race.
Trial shaft/caisson.
Shafts, exploratory deve lopmenl •
Prtmnrv h=:vl'l normRll~ adequate for
qeneral !'tt.'pping.
Advanced stage usually reserved for hard to
detect cnt 1cal features. Special r&rely
used in qeotechnica1 work.
Advanced st aqe usunll y reserved for hard to
detect-critical features. Special rarely
used in geotechnical work.
level normally progressively increases
from reconnaissance through construction.
New precision equipment fre-que11t1y
cheapest~
Sound mas and sonar prof1l1nq usun 1\ y
adequate ..
Geotechnical level seldom exceeds the
advanced phase.
Geotechnical level seldom exceeds the
advanced phase.
Primary usually limit of methods used.
Level usuallv advances throuqh reconnal~$ance
to final design programs.
•·See logging and mst.rlJllent at )on su:nm<>r~.
NorrnaHy limited l o pnmary methods.
Level advances through reconnaissance to
f~nal des~gn programs.
Level depends on exposure availability.
Level depends on exporure availah1lity.
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TA£3t E 1. 1: EXPLORA TillN l•lETHODS (Cant' d)
~~--------------------r-------------------------~----------------------------------------·----·L~Envtnc~o~r~sno~prrA~r~s~ri"t~.A~r~tonNr---------------------~--~--------------------------~~------------
GENERIC ACT!' T_Y ___ +------R..;.;E..;..CO.;...N_N.;...A...;.l..;..SS,;-..;A..;..N...;.1C"""'E----+--------P-R..;..IM .... A_R_Y ______ t------A-OVANCED SPECIAL
INSTRUMENTATION & TESTING:
Water Table L.etection
Water Table fbnifor1ng
Water Quality Testing
Ground rlater Flow Heasurement
Permafrost Detect~on
Thermal Mc-uHoring
Thermal Properties
Determination
Permeability
Groutabil ity
Geologic Age Determination
Slral1.graphy -Horizons
-Oenstty
-Moisture
-Cant mu1 ty
-Chemistry
Bonng -Inclination
-Duection
-Condl t. ion
Rock Fractures/ Joir.~s
Rock P ~opert Jes
Surface waiers reconnaissance.
Surface reconnaissance
photography.
Surface sampling.
Surface mapping.
I
Resistivity probes, standpipes, air
1 i fl recovery.
floalst standpipe measurements.
Ba.il mg, pU."llp samp Ies.
Dye tracing, piezometers.
Thermometer on surface matenals Visual/thermometer on recovered
and water, inferred photography. 1 boring samples, down hole probes.
RepetJ.t ive thermometer readmgs. Thermal probes.
Based <Jn material type, gradation. Disturbed sample laboratory testing.
Based on mater.i.al t·ype, gradation. Standard casing or packer testing.
Estimat.e based on material grada~
tion, fracture frequency.
Based on published geologic
history of area.
In fer red from geo 1 ogy, surface
samples, standard drive samples.
Inferred from geoloqy, surface
samptes, standard drive samples.
Inferred from geolog:-, surface
samples, slandard drive samples.
Inferr.ed from geology, surface
samples, standard drive samples.
"PPjari", s1ngle-shot camera.
Single-shot compass camera.
Caliper Jog, res1st1vity,
gamma loqs.
Recovered core, oulcrops.
Recovered core,. outcrops.
Based on permeability, single-hole
test grouting.
Based on mapped stral-1graphy.
lnsper::tion of recovered samples.
Drilltnq, surface qeophys1cs,
standard drive penetrat1on.
Recovered samples.
Multiple drill holes with test1ng of
r~covered samples.
Recovered boring, ground water
samples.
"Acld Bottle" or incllnometer.
Inc l i nor1et er.
Borehole camera.
Borehole camera/v1deo.
Laboratorv tesring of recovered
core, dm1n hole se1sm1::=, ga"":v;a
logging.
* Se~ 1nstru:nenl abon and tesl1ng interpretation.
Piezometers.
Piezoneters.
Elect r1c mt>t ers.
Downhole flm-1 tracer (flowmeter}
Multi-point thermistor stnngs,
Infared scanning.
Thermistors.
ln-place ther~stistor evaluation!
undisturbed sample laboratory
testing.
Grouted packer or well screen
testing.
01electric, sonic prohes.
El~ctric, nuclear recorders.
Coni inuous automal1c sampler.
Rad10nucl ide t.racing, integrated
analog coupled pl~zometers.
Automatic continuous readmq
system of therMistors. -
Automatic continuous read1nq
syslem of thermistors.
Continuous prof1le recorder data
regression analysis.
Large-scale aquifer pump testing
w.it.h multiple holes and observa-
tion systern.
Multiple-hole test qrout. proqram. full-scale test with subsequent
coring, excavation to check
effectiveness, losses.
Radio carbon, Potassiun-Argon,
StrontiUhl dating.
Resistivity! qamma logging.
Neutron density (gamma}.
Spontaneous se1sm1c, resist iv-
J.ty, qamma.
Cross-hole seismic, res1stlv1ty,
gamma.
Electric inclinomet~T·.
Electric down hole compass.
Acoustic profller.
Caliper loq, acoustic prof1ler.
Goodman jack, CSI~ or plat v jock,
cross-hole se1sm1c.
I Remnant magnet isn, salt concentra-
tions, rad1o-isotope concentration
and ratio companson.
Down hole photography.
In-situ samplinn.
E-~1 mduced currf."nt, cross-hole
radar, rad10.
Gyroscopic surve}'Or.
Gyroscop1c surveyor ..
Dmm hole displacement probe,
down hole radar.
Dovm hole radar, acoustIc profl1 es
(SCAT), X-ray dlffractJon.
Hydrofradurinq1 overcormn-
NOTES
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TABLE 1.2 -DETAILED EXPLORATION METHOD BREAKDOWN
1. SURFACE OBSERVATION
MArPING
REMOTE SENSING
2. DRILLING
PLUG/PROBE
OVERBURDEN
SAMPLING
CORE
3. EXCAVATION
TEST TRENCH
-Air photo base field mapping
-Detailed base map field mapping
-Plane Table
-Tape & Brunton/studies mapping
-Theodolite/precision survey !"lapping
-Vertical, high and low oblique, horizontal surface controlled
and uncontrolled photograph¥
-Tele-photo or photo-transit ground photography
-Satellite imagery/mult1-spectral thematic scanner
-Aerial narrow-band scanner
-Towed magnetic, gravity, rad1oactivit.y, gas detectors
-Aerial strip, s~de look1ng, integrated scann1ng radar
-Airborne thermal infared 1magery, thermal thematic mapptng
-Rotary drag or tricone dr1lling
-Rotary-percussion (blast drill)
-Percussion (airtrack, jackhammer)
-\~ash boring
-Jetting/chopping jet drilling
-Spira~ or single flight augers
-Hollow stern augers
-Bucket auger
-Reverse circulation rotary
-Reverse circulation rotary-percussion
-Churn
-Rotary coring
-Spoon and tube sampling
-Rotary drive barrel sa.rn,·,ling
Penetratometer/vane shear testing
-Rotary carbide or diamond
-Hollow stem drive cores
-Calyx
-Reverse circulation "air lift'• cor1ng
-Test trench -hand
-Test trench -dozer, backhoe, dragline
-Test trench -chain or belt excavator
-Test block ~ in-situ hand excavated
-Test block = sawed or sliced
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TABLE 1.2 (Cant'd)
TEST PIT/BLAST -Hand dug sample pit
-Hachine sample test pit
-Explosives sample test pit
-Hand dug "channel" or "black" sample
-Machine excavated rock face
-Test blast
CAISSON/SHAFT -Hand-du~
-Backhoe 1 clamshell
-Drilled/raise based
-Mechan1cal drill/blast/muck
-Caisson
-Bucket 'auger
-Calyx
ADIT -Exp !oratory adit
-Drilled acces~
4. SURFACE GE8PHYSICS
-Seismic refraction
-Se1smic reflection
-Resistivity
-Sonar/sonic profiling
-Magnetometer
-Gravimetr.•r
-Radar
-Radiatiun detection
-Gas sensors
5. PERMANENT DOWNHOLE INSTRUMENTATION
THERf4AL
PIEZOMETRIC
DO::FORMAHON
-ThermocoupJa/thermistor strings
-Thermistor probe standpipes
-Recording ther~~meter
-Standpipe
·~ Pneumatic
-Electric, dielectric
-Nuclear probe
-Mechanical float
-Continuous automatic sampler
-Inclinometers
-Extensometers, borehole
-Borehole deformometers
-Adit/opening extensometers
-Seismometer
-Impression packers
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TABLE 1.2 (Cont'd)
6. DOWNHOLE TESTING
NATER LEVEL -Manual "plunking"
-Air lJ.ft
-~'W' scope ( res~stiv fty, 10n detection)
-Piezometer
-Son1c probes
-Bailing
-Imagery (see follow1ng)
-V1sual/mirror
PERMEABILITY -Open hole tests -falling head; constant head; rtstng head;
pump recharge
-Packe~ pressure test1ng
-Cross-hole dye/radionucl~de testing
-Downhole borehole flow meter
-Coupled piezometer readings
-Electro~magnetic 1nduced current
SEISMIC VELOCITY -Single po~nt "P" wave
IMAGERY
DENSITY,
MOISTURE
t-tODULUS
HARDNESS
-Single point Shear ("S") wave
-Multi-point "S" wave
-Cross-hole seism1c
-Borehole camera-single shot ("bullseye"); reel or
circumferential (conventional); video; televiSlon
-Acoustic profiling (SCAT)
-Thermal profiling
-Downhole prof~ling d1electric response radar
-Fiber optic "periscope"
Digital imag~ry processor
-Nuclear (gamma-gamma)
-Induced res1svitity
-Nuclear (neutron density)
-~~ontaneous potent1al
-"Chirp" acoustics
-Cross-hole tad1o
-Probs (physical penetratl:on)
-Plate Jacking
-Rad1al Jacking ("Goodman" type)
-Dllatometer
-Dynam1c shear wave
-Direct l~boratory stress-stra1n testing
-Nuclear logging
-Downhole penetrometers
-Dr1llability index, petrographic tests
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TABLE ·1.2 (Cont'd)
IN-SITU STRESS
INCLINAriON
DEFORMATION
-Oriented jack1ng
-Overcor~ng (CSM, CSIRO, USBH)
-Closed tunnel pressure tests
-Hydrofracturing
-Screw-plate tests
-Inclinometer, electr~c
-Impression packer
-11 Ac~d-bottle" inclinometer
-"Pajari" type deviation meter
-Gyroscopic surveyor
-"Totco" type inclination smgle-shot 1nclinometer
-Extensometers (rod)
-Caliper
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TABLE 1.3-SPECIFIC FIELD AND LARORATORY TESTS
The following list is Intended to be representative of the generic parameters or data
collection methods that will be utilized, as approporiate. Within each paratneter, a
number of specific test procedures are implied for evaluation of various elements,
factors. or variables within the general narameters.
1. WATER
GROUND WATER -Piezometric levels
-Aquifer transmissivity, anistropy
-Aquifer permeability
-Aquifer source determinations flow tracing, gradient.s
QUALITY -Drinking & camp use
-Closed circuit cooling, HVAC use
-Effect on permanent 1nstaUat1on (prec1p1tation, corros1on
solulion1ng)
-Concrete mix ••sa
-General environmental discharge acceptablllty, post-pr~ject
(Relict Channel. drainage facilities)
2. SOIL AND OVERBURDEN -IN-SITU
3. ROCK IN-SITU
-Composition, petrology, strat1graohy
-Gradation
Weathering.. age
Perrr.eability
-Dynamic behavior
-Density. porosity (disturbed and in-situ)
-Swelling/collapsing behavior
-Petrology
-rhneralog1cal composition of critical material
-Rock quality (fractures, void<:;)
-Wp~f-hering, age
-Permeability
-Strength -mass and d1Econt1nult1es
-Existing stress conditions (downhole jacking; overcor1ng;
pressure testing; plate jack£ng, etc.)
-Mass seismic velocity
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1ABLE 1.3 (Cont'd)
4. CONSTRUCTION MATERIALS
AGGREGATE,
FILL MATERIAL
CONCRETE
PAVEMENT
(ncn-conc-rete)
-Mo~sture, absorpt1on
-Gradation
-Oenstty
-Impurrties, adverse constituents
-Weathering resistance (shrinkage, soundness)
-Processing resistance (L.A. abrasion)
-Alakali reactivity
-Freeze-thaw resistance, frost heave susceptiblllt.y
-Adverse coatings, leachates
-Petrology
-Strength (static, dynamic-compressive, tens1on, shear)
-Placement/compaction properties
-Permeability & consolidation behavior (laboratory and test flll)
-Dynamic behav~or
-Piping, erosion behav~or
-M~x design, spec1fications
-Strength
-Modulus, Poissons ratio
-Weathering res.tstance (soundness)
-Freeze-thaw resistances
-Mix design, specifications
-Penetrat~on reststance, strength
-Thermal performance
-Part~cle surface bond1ng character~stics
5. THERMAL CONDITIONS {applies c.:nly to permafrost areas and c.r1t1cal earth fill materlals)
-Incident energy, degre~-day environ;nent
-Permaf:.::Jst detect ion
-Conductivity (lab and by retrof1t of temperatures at
depth to kr'lown inc~dent energy)
-So1l creep, consolidat ton propert 1es when frozen
-Static, dynamic modulus (compressi.ve, shear)
-tleat capacity, diffus1v1ty
-Frost suscept1bil~ty
-Freeze-thaw expans~on/contract~on
Compactive effort on frozen so.1l at various degress
of saturation
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.
z c ...... .....
··z d;
c .....
1->-_J
< .,... c -c..; a.. ...._
_.;,...... < ' < ;.. C! w t.: c: 1:.::; .,_, ........
......... •-"' -< z ~-:-,... 'I:-> ,_. ;:::< ~ d; 0 c. <-' u
:: t .. .:: ,_ ' ' PiW$1CAL OR SAI·PLING FACTOR . .., u c w,
(INDEPENDENT fACTOR)
TOPOGRAPHIC:
Elevation 0 0 --Depth frorir Surface 0 + -+ Depth Into Rock 0 + -+ lateral Extent + + + 0 Exposure Direction ----D~stance from Surface \'later ----Topographic Morphology ----Depth above/below Hater Table 0 ---
GEOLOGIC:
D1stance from Geologic reat.ure + 0 + -Geomorphologic Location + + --Roci{/Soil Type I + + + Permeabil ily --0 -Density ----Pel'mafrost ----Hocl<. Quality/Fractures -+ 0 -Stratigraphy + I + +
SAMPLING: (or Test Zone)
Sampler Diameter ----Sample Volume ----Sampler Type --- -Samp 1 ing Pre ''tre -0 --Test ~let hod ----Test Procedure ----Sample Handllng -0 --
~ Likely to be a s1gmf1cant Influence or correllat ion.
0 Poss1ble Influence or correllation.
Unlikely source of mfluence~
I Not applicable, or identify case.
u..;
" ......
IJ')
w
...J u -:z !-c a: -< ._ c..
< c .
< X ; < ::..
0 0
+ + --
+ 0
0 -
0 -
+ + --
--
+ +
+ +
+ ---
0 --+
+ +
+ +
+ -
0 +
+ 0
+ +
+ +
0 +
TABLE 1.4~ tormrtATIOI~ HAHtlX Of POTENTIAL RELATIONSHIPS
I·~Alt.IUAL t'JmPEHl? OH CW\UITID\• nE 11 n m~·~ f! ' . -..~iTR~!)~i~~~~~~~~~r-------------------------------~------------------~ FA
> ,_
......
> Ill ..... ,_. :r. >
tn ...._
....... c:; z :::< >-c ~ c ._ ...........
Z>-t.:i ;:> ..... E: . z ........ ._J Wd; c::: :I: z ...... ;:-...... ........ c ~ 1-c cr >-to u·....-1-> c; ...... w 1-...... < .... ::::
:I: l"' w l>.C 1-cr z fJ: ~ w w ,_ :E: l>. ·~ t.r: w U"' ~ ~ . >-c::: = c::: cr wz -z < ..... 0 w L;. c: .!...J DC c ttl u ::;t: ~ 0.. Cl.. uu :::E: :;.".:
....... ..... w ........ .... ::::: r.r. 1....: c::: .......
ttl ...... ttl r..: :::) w z ....! w z 1-c w c:: c: u >-._J
r.."l C) ..... !-c::: ....... 1....: .....
ttl c::. ttl l.f' c::: ...... > ttl
t-'7 u w t... > c ..... c:: ....... tn ' ...... u c:: w z ..-c:: ..... Lw tf} c.n 1-u...
@ < w ...... c::: I:-c:: tfl ~ < til 7.: < ..,. z ...... .6:: <t: >-1-I ,_ -~ tn
:t: 0 c::: 2 C-c !...; ;;; w ..... ttl r-:l t:< c:: !!...
.
l
-----Qc + --
+ + + 0 + + 0 --
+ -0 + -0 0 --
0 0 0 0 0 + 0 --
+ -0 --0 0 --0 0 0 0 -+ + --
+ + 0 ~ -+ + --
+ 0 0 + + + I 0 0
+
0 + + -} + + 0 0 + 0 + I + 0 + + +
0 0 0 + 0 0 0
0 0 0 +
0 + + + +
0 0 + + 0 0 0 +
+ 0 + + -+; +
0 -D 0 -0 0 0 -+ -+ + -+ 0 --
+ + + + + 0 + + +
+ -+ I 0 + + 0 0 -I -0 + --+ 0
0 0 0 + + + + + +
+ 0 + + + 0 0 0 . + + 0 0 +
+ + + + 0 + + 0 + + 0
0 + + 0 0 + + 0
+ + + 0 + 0 + + 0
+ + 0 + + + I + + + + + + + + +
+ + + 0 -D -+ +
+ + + + I + + + 0
+ + 0 0 0 0 + + + +
-0 0 + 0 --+ + 0 + 0 + + + + + 0 .... --+ + ------+ . + + 0 + -+ +
0 + + + + + + + +
+ + 0 + + + 0 + + 0
+ + + + + + + + + + 0 + + + 0 0 0 0 + -+ + + + -+ + + -+ + + + + 0 + ... + + + + + + 0 0 + + + + + + + + + 0 -+ + -+ + -+ ~ + + + + I I +
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TABLE 1.5: GEOTECHNICAL INTERPRETATION WORKING MEDIA
PHYSICAL MEDIA Borehole "stick" models represenUng explorations in three
dimensions.
CARTOGRAPHIC
GRAPHIC
MATHH1ATICAL
-Physical prof1le or "fence" diagrams w1.th wood cross sections
on a topographic base map creating an intet"locking "fence"
network of sections.
-"Block" models of geologic conditions or borrow material areas.
-Rock and soil sample comparison boards showing "type'~ samples.
-Isometric "fence" diagrams and sections.
-"Isopach" or 11 1so .. value" maps of particular properties or
physical characteristic.
-"Layer" maps of data grouped by type or magnitude of feature
or characteristic.
-Plotted weightings of vertical averages includmg "strip",
"triangle", and weighted cumulative "depth" block analyses as
applied to mining reserve calculations for determination of
weighted or area average values.
-Two and three-variable plots on rectangular and triangular
graphs~
-Summary plots and range-of-value graphs of physical sizes
orientations, propert1es, typically including the followlnq
typical properties:
• Gradation and grain size coefficients;
• Rock quality indices;
• Permeability and temperature data;
u Moisture and Atterberg limits; and
• Rock and soil classifications.
-Geologic sections and elevations includ1ng borehole logs and
stratigraphic colt.rnns showing several factors on adjace~t
colunns.
-Statistical analysis, such as:
• Means and standard deviation comparisons;
• Method of moving averages.; and
• Monte Carlo simulation.
-Mathematical correlation determination by:
• Linear and curvilinear regression;
• Multi-variate correlation analysis; and
• Distr1but:ion curve-f1tting (\'/eibull or equivalent).
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TABLE 1.6: INVESTIGATIVE PROCEDURE-SCOPE PRESENTATION fORMAT
OBJECTIVES -Design data requirements.
-Requirements for in-situ natural condition data.
-Known conditions needing clarification.
-Potential conditions needing clarif1catiun.
-Data/parameters to be acquired in this scope objective.
APPROACH -Exploration methods planned for known and potential conditions.
-Design pararaeters (initial) development.
-Preliminary design.
-Test for cost/design sensitivity to p2rameters.
-Modify/optimize parameters/design.
DISCUSSION -Interaction w1th design disciplines.
-Optimization coordination-schedule and costs.
-Simplification/standardization of design.
-Other major aign1ficant factors •
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YEAR
1918
1952
1957
1975
1957 -58
1960
1978 -79
1975
1980 -1982
Scheduled
(1902 -1984)
(1985 -1994)
(1993 ---)
FIGURE 1.1: SCHEHATIC 'JF' PHASES OF' GEOTECHNICAL INVESTIGATIONS
PHASE
SITE
IDENTIFICATION
SITE
RECONNAISSANCE
PREF'EASIBILITY
STUDIES
.
FEASIBILITY
DETERMINATION
FEASIBILITY
CONFIRMATION/
REEVALUATION
DESIGN LEVEL
CONSTRUCTION
MONITORiNG/
VALIDATION
OPERATIONAL
MONITORING
PERFORMED BY
USGS
USBR
.USBR, USGS
CO£
USBR, USGS
(Watana & Devil Canyon)
(Watana & Devil Canyon)
{Devll Canyon, Transmiss1on
Access Routes)
{Watana)
(Devil Canyon, Transmission
Access Routes)
USBR (Report) (Devil Canyon)
COE {Watana, Transmisslon)
Alaska Power Administration (Report)
Acres
Commonwealth Assoc.
AcresiR&M
TO BE DETERMINED
(Devil Canyon, Watana)
(Transmission Intertte)
{Transmission, Access
Routes)
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FIGURE 1.2: GEOTECHNICAL PROGRAM FORMAT-WATANA
DESIGN LEVEL
GEOTECHNICAL
INVESTIGATIONS
PROGRAM
GOALS I
i'
PROGRAM
DEVELOPMENT
METHODOLOGY
...
.
--"
GENERAL
SCOPE
OF WORK 1-----·------J;.'*
1982 -1983
GEOTECHNIGAL
PROGRAM
PROGRAN DATA
REQUIRENENTS
(OBJECTIVES)
,
CONSTRAINTS,
PHILOSOPHY
OF SAf.PllNG
PROCEDURES
PROGRAM
SCOPE Of
WORK
1 • b
GENERAL IL! DETAILED
SCHEDULE & r----------:~-SCHEDULE, PRIORITIES l'Jo> BUDGET
...-
..
ADDITIONAL
CRITERIA INPUT,
ASSOCIATED
DOCUMENTS
GEOTECHNICAL DATA
REQUIREHENTS
SUHMARY
(CHECK LISTS)
EXPLORATIONS
INVES TIGA 1' I VE
NETHODOLOGY
(TABLES)
GEOTECHNICAL
PROCEDURES
HANUAL
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196'2 1963 t 1984
J F M A M ! J i J I A I S ' 0 J N I D J I F j·M A ! M l .J J ! A I S i 0 I N J 0 f J ~ F I M i A 1M I J 1 J t~ s I 0 t N ! 0
l Ill II I ~ l.
1 l I l r : ·'! i ; , t ~ l I I .I
J
1985
FIMJAIM!JIJ l A .~ S ! 0 i'~
WATANA
BORROW AREAS INVESTIGATION /RESERVOIR
GEOLOGIC MAPPING
DRILLING & TESTING
LABORATORY TESTING
GEOPHYSICS
t ' . I t I i : I l 'i .. I I·~ I I I j ~ I I ! I I I ; i i,: j i I
1 1 1 !-; 1 1 I . 1 1 ' 1 1.· • 1 'r· .. · .~.. ; j 1 !
. ; 1 •. ~'._i_.~.U-+~;~·f_.:_.~f.am; ._ .. _..'._.:._._.l_.r-.~ _.1.--.1~· ._~ ... ~ ..... : ...... : .. · ... J~i r ~ , ~ :. · . . , i •. 1 , ~
I ! 1,! I ii I~ I
i I
l ~,: ! I ! I I ' I I I ~ ! ' l i l i l
.. il ' I . I ilia& • i j I ,. I ' ' I I ; I t----R-E_L_I_C_T~C-HA_N_N_E_L_IN_V_·-ES_:f_l_G_AT_I_G_N _____ -+-____,....__...:.:. -:-t
1
. --'-.-t--__;_; -+~ -~-_._j---:l-+-_,; __ • ___,:--; --i--------,.-~1 ·;· . ~~:4--, -+.!' -! •• -+,: ____,:_.,..;_' --+-J-I.__; ---+j--'-l ---t-j'"~" ~
I jl I l '' I 'l l ! j ' I I !
. ; ; :I l i! :I l!:: IiI: l: : l J! l ::~~NA::R~~::~NG ,: 1 ;: ~ !RIIIjl'~·-*_'.,~--~ _.,_,_ .. i __ ~ ...... .!..~-: ~l--111!'-~~-~!11~ .... : . .-'lllr·!-1· :·lll--~::.jll,:-~-~~:-~1-.jll_.i -~ i i ,: -,··. : 1 1~
1
4
! l I • I " I l ~.· I I 1:' 1 .,. . t t-~--~-----------------1---t--+-t--+•-t---+--+--+-+--+--+----+-+---!--+-' ---f-+--+----+-f--.,_j-.,--·-··--+--+----+~f---!--+-___._j..-.J.--+--+---4-+--''I--+-·~t--+--+--+--ii----t-------+.-___,_--"t···~-----l
DAMSITE INVESTIGATION I I l I I
GEOLOGIC MAPPING l ~-~~ ~--' lllll!llfJt .... 1.11 11111111~ .. 1111!--!&!llllifl~ I I
! I ri I I 1 I i -i..... ...,; I I I H ! I I l l ! I ! l I GEOPHYSICAL SURVEYS
DIAMOND DRILLING
RIVER DRILLING
TEST ADITS
LABORATORY TESTING
ACCESS ROAD *
DRILLING a TESTlNG
I I. I 1,1 I i I I i I I t ,. ! I i ;
' I 'i I lilT I I! I l
J 1-............ ~n•~•n••u• I II J I I I I i l
I I
I
I I ~ j
I t i I l ~ I
TRANSMISSION LI!\IES *
l. I l.· ~.; .. ·. 1!. I I ~ I I 1 . ; I ! ! j ~ t , J ~-----·-------------·---------1---t--+-t---t--+--t-t--+--i-: -+-+--+--1---+--+--t---i--t-t --t-,__.. T~--~· --J f-· t-· -t---+--t---r--Jr--+---+-1 --.~-+--t--+--t!-=--.
ll ! II I IIi II I DRILLING a TESTING
DEVIL CANYON **
DJ[\.MSITE INVESTIGATIGN I RESERVOIR
GEOLOGIC MAPPING
GEOPHYSICAL SURVEYS
DIAMOND DRILLING
ll! I! I ! t l I i I J ! ! ! I i I 1;
ll. l !· II 1, I 1 I I I ! ; l ~ ' ,,. li ~ : ~,' 1~1 '·.·. t' l i I ! l I I I i I> ! 1 I:;
l!! II l i I : I' ill I; i l i I'! I I i i l l I I I I I l 1
11 ,. i I l l I i l i ' l J
1 ! l I ; ; i l ; . I : I 1 1 1 i 'i i : · ! , 1 1 • ' I : , I : I I l I! l 1 1 ., • I I I 'I: I' l
I ., l I I I I I I II i I : ; I I
TEST AD ITS 1'.1 II l I ll '· !' ,' l . ! l l ' ,. I
i t I ' I ! ' I
LABoRAToRY TEsrtNG 1 1 1 1 l 1 . f 1 1 i '. ; ! ....... i __ ·~---f-_,.L-+---+-....... l _____ !·-+--··-· .... 1 ..... ·.---r'.··-··"·····+·), ~--s-o-R~:_:_:_L_:_:_~-a-1 :_:_:_~_:_:_A_T_to-N-.----~~,~~~~-!~:~~~~~~~.~~~+,~I~i~~+l~~~-~~,-rlll-TIT--l-~r 1r ~~: ~~~
LABC)RATORY T .-STING I ! .~!. i ' l. I. ll I 1 F : l 't ! ' ' ! l ,1·.~ ,.-1! i . ! I ; I'
. . . . t: .· . I I I I i J J t i t l ! 1 ! J I J l ! I i I ! l : I I
* TO BE DETf'r"MiNED At A LATER DATE
~SCHEDULE FOR INVESTIGATION IS 11EPENDENT
ON DESIGN a CONSTRUCTION SCHEDULE
1982 -85 PROPOSED GEOTECHNICAL INVESTIGATION PROGRAM
i I ~
~
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!
... II. ~
' I I I I .........
l . l
I !
! i,., ~i-1!111. -llllll::...:j l
FIGURE U3
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FIGURE 1.4: EXPLORATIONS PROGRAM DEVELOPMENT
LEVEL OF EFFORT
Individual team members plan
program in respective area
of prime expertise
--------- ----
Team review with d1rect
first level management input
Team concurrence
-----------------
Full managerial and 1n-house
consultant review
.t\CTIVIfY
ITEMIZE DATA
REQUIREMENTS
' PRIORITIZE & SCHEDULE
ACTIVITIES
~· I
DEVELOP RECDt·1HENDED
SCOPE
I
EVALUATE RECot-tMENDED
SCOPE
' DEVELOP PRELIMI~AR\'
ITEMIZED SCOPE
' ASSESS CONFLICTS,
OVERLAPS, PRIORITY
CONSEQUENCES
l
DEVELOP RECOMHENDED
PROGRAt~
' RESCOPE AS NECESSARY
~"""!-----------
PRODUCE FINAL SCOPE
I
ESTIMATE COSTS, DELAY
POTENTIAL 1--------------
DETAILED SCHEDULE
' .
PRODUCE CONTRACTS,
ACQUIRE MATERIALS
OBJECTIVE
"Wish List» of 1nforrnat1on needed
for design activtties.
Balance data requirements against
design demand and prtortties, design
schedule.
Scope out realistic program within
budget, schedule constratnts.
Evaluate best methods of data
collection.
Match data requirements to explora-
tions methods to develop detal.led
methodology, assiqn levels of effort
for each data collection activity.
Evaluate conflicts between various
data demands and exp lor.ation/de.stgn
schedules.
Produce recommended proqram combin1ng
all indtvtdual team membe~~" .requirements.
Incorporate comments.
Product detatled scope of work state-
ments, plans.
Detailed schedule and program cost
development.
Program preparation and mobilization
activit 1es.
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FIGURE 1. 5: SYS TEt4A TIC P.ROCEDURE FOR
EXPLORATIONS AND DATA INTERPRETATION
LEVEL OF SOPHISTICATION OBJECTIVE & DATA INTERPRETATION
RECONNAISSANCE LEVEL
ACTIVITIES
PRIMARY
INVESTIGATIONS
,r
ADVANCED
EXPLORATIONS
L_
,
SPECIAL
TECHNIQUES
_ Identification of targets
~ for detailed investigations.
...
-....
-
Pattern recognition to
allo~ construction of trial
interpret1ve model and
general picture of material
properties ..
Search for specific detailed
data necessary for. design
parameters and test the
abil1ty to model the in-s1tu
cond1tions. Includes samp-
llng of homogeneous materials
for statistically valid par-
ameters, and of pervasive or
continuous non-homogeneous
features for contifluity ..
Detailed evaluation af.ln-
situ properties of conditions
which are critical to design
or analysis but cannot be
reliablv determined from
rout1ne' investigations.
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FIGURE 1.6: DATA REDUCTION AND COMPILATION PROCEDURE
FIELD PERSONNEL OFFICE PERSONNEL
1 I COLLECT & DOCUi·1ENT LOG IN RAW FIELD
FIELD DATA DATA
,,
PROOF, EDIT REVIEW, LOG
FIELD LOGS -FIELD DATA
'f ' ·-
PLOT DATA PRODUCE FINAL PLOT EXPLORATION
ON NAPS .. I FIELD DATA -LOCATION DATA
-, r ,.
PRODUCE FIELD SUHHA.RIZE PERFORM.DATA
INTERPRETATION FIELD DATA COMPILATION &
CORRELATIONS rr-... -
PRODUCE SUPPLEMENTAL _ .. PRODUCE SUNMARY PLOT FINAL
LOGS, SAMPLE INDEXES ~ LOGS DATA
, ,
REVIEW, COt-1t4ENT ON I SUMMARY TABLES, ·' FINAL DAU. -FINAL LOGS
PRESENTATION
,
. " l
REVIEW, COMMENT ON PRODUCE FINAL
INTERPRETATION --INTERPRETATIGN
DATA PRODUCT
I FILE ORIGINAL ~ FIE:LD LOG
~
~ FILE At-1ENDED
CORRECTED LOGS
PRODUCE LOCATION, -FIELD DATA MAPS
PRODUCE -LOCATION MAPS
PRINT FII\JAL _. TABLES, LOGS
PRINT FINAL -SECTIONS, MAPS
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2 DESIGN LEVEL GEOTECHNICAL INVESTIGATIONS -WATANA
2.1 -Program Development
For purposes of program seeping, the watana geotechnical investigations have
been broken out by physical areas in which the work would be performed, as fol-
lows; and each scope statement will be outlined in the presentation format shown
on Table 1.6.
-Damsite -Abutments and Underground, including all power facilities, under-
ground structures and tunnels, and spill\'Jay facilities.
-Damsite -River Area, including all foundation areas within the active flood
plain, river grout and cutoff sites, cofferdam sites, and plunge pool area;
including adequate upstream and downstream coverage of areas where riverbed
material removal may be required for diversion training or outlet channel mod-
ifications.
-Relict Channels, including both the primary concern area between Deadman and
Tsusena Creeks, and the southern Relict Channel between the Susitna River and
Fog Creek, designated the Fog Lakes Relict Channel.
-Impervious Boirrow Sources concentrating on Borrow Area Site D, with Borrow
Site H being discussed as a potential backup source.
-Granular Fill and Aggregate Sources including Borrow Sites E, F, I and J. with
emphasis on Sites E and I since this combined area is currently expected to
produce essentially all the concrete aggregate, filter materia·!, and d~~ shell
material for the project. Borrow Sites F and J will be covered by the geo-
logic mapping and general limit delineation seismic investigations, but since
they are not critical to project feasibility or 1nstruction costing, drilling
and 1mpling operations can be delayed until the critical geotechnical invest-
igations at the damsite, relict channels, and primary borrow sites have been
completed.
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-Rock Quarry Sites including Quarry Site L, which has been delineated for
potential cofferdam construction, and tJuarry Site A 'fllhich comprises the backup
quarry. Because Site L constitutes a potentially lower cost and more readily
developed shell material source than Site E, it comprises a backup to ;SitE~ E
which is not critical to schedule or overall costs. The site will be
in'!estigated to determine its suitability for use, and the magnitude of it.s
potential for shifting shell material development off the critical path in the
cofferdam construction schedule. Quarry Site A should be investigated later
in the program to the feasibility level only to assure that it constitutes a
viable backup in case of need.
-Reservoir contairnnent and operational factors and constraints including poten-
tial for water losses, slope instability or failures, and environmental conse·
quences of operation from the geotechanical factors vie\·lpoint:
-Auxiliary Facilities inc'luding construction camp and permanent village facil-
ities, airfield, off-site maintenance, recreational, and-associated
nor.-operationa1 facilties.
Each wr·iteup will discuss the more critical or specific conditions and para-
meters which may affect design of construction:; assuming the exploration altern-
atives presented and discussed in Section 1.2. The ~eneral rundo'lm of yeotech-
nical parameters ana objectives Hhich may be considered for each particular
feature or structure is presented in tabular format, as for example in Table 2.1
for the damsite areas. The objectives \vill be discussed in the text only for
the most critical and controversial cases. The subsequent approach and discus-
sion statements will then cover the particular techniques or unique application~
which might be used in the geot~chnical investi]ations, with a tabular format of
recommended exploration methoc3 sur1111arizing tt·~ e1tire range of structures, as
for example ir. Table 2.2,. for the damsite areas. The tabular forillat is appli-
cable to each section, lising the particular problems anticipated and the
probable explorations methods as applicable to each major structure or iden-
tified features.
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1.2 -Design Level Geotechnical Investigations -Watana
(a) Oamsite -Abutments and Underground
Objectives
The obJective of this investigation Hill be to obtain the necessary
design level geotechnical data to finalize the general arrangements,
to establish construction costs and schedules for the surface and
underground civil features (Figure 2.1). This data will consist of
the geology and engineering properties cf the materials on the dam
abutments and underground. The investigations wjl1 examine geologic
conditions and geotechnical problems within the damsite area that were
identified in the 1980-.81 Geotechnical Report and need fur·ther study.
In addition, provisions within the program should be made to examine
any as yet unkno\'m conditions which may become evident during the
design level investigation.
Table 2.1 is a matrix of the 'types of geotechnical factors which vlill
be assessed for the surface and underground civil structur~s {Figure
2.1) vtithin the darnsite area. The matrix is a prioritized system
wllich shmcJs the criticality of the geotechnical factors to the design
of the civil structures. The rating system ranks the geotechnical
factors on a scale of 1 to 4~ with 1 being critical to des1gn and 4
haviny little engineering impact. This system is descr·lbed in de·cai 1
on Table 2.1. The geotechnical factors for vthich data vlill be ac-
quired are divided into the folio\'Jing categories: geuloyic, physical
environmental, geomorphologic, in-situ material properties and opera-
tional properties. The criticality of design level data in these
catesories is discussed below.
Geologic factors include lithology and discontinuities. KnovJledse of
lithologic variations is essential to the design of both surface and
subsurface structures, but is not critical to the general arrangenent.
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The location of discontinuities will have major impact on the orienta-
tion and support requirements for underground structures and on the
large rock cuts in the main spillway •
Physical factors include the surface water, ground water, and thermal
characteristics of the damsite. The surface and ground water charac-
teristics will impact on drainage requirements, concrete mixtures,
linings and construction methods. Thermal conditions which will
impact on the site are permafrost and the presence of free ice. These
conditions could lead to differential settlement under surface founda-
tions such as the freeboard dike. The effect of water and thermal
characteristics will primarily influence costs and scheduling.
Geomorphology includes topography, weathering and stability in the
dams it e. · The topography of the ground and bedrock surface wi 11 affect
the location and depth of excavations and so will be a major influence
on the arrangement of surface civil features such as the dam and
spillways, as well as the diversion tunnel portals and power intake
structure. Rock stability in the damsite is primari:y related tQ the
d·iscontinuities which are discussed above. The underground structures
are affected strongly by unstable rock conditions and will be lucated
and oriented to minimize the effect of discontinuities. Potential
stability problems following inundation could affect the materials
beneath the freeboard dike, as well as cuts at the power intake and
diversion tunnel portals. Both rock stability and post-inundation
stability data are essentia~ to the general site arrangement
In-situ material properties include those physical characteristics of
soil and rock which are measured in the field or laboratory. Rock
I
properties such as compressive, shear and .. ensile strengths are re-
quired to determine the behavior of the mass under various stresses
which \'li ll occur in foundations and underground openings. The effect
of rock strength is generally not as critical a-; the presence of dis-
continuities in the rock ma~1 so these properties, although essential
to design, are not normally critical to general arrangement.
2-4
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Soi 1 and overburden properties \'lill only have a major impact in the
area of the freeboard dike, because they are normally removed under
the major structures. Radical changes in overburden thickness, which
is also included in this section~ can affect estimated dam quantities
and necessitate changes in general arrangement. Underground struc-
tures are not effected by overburden thickness except at the portals,
where unanticipated thicknesses wili affect cost and schedule ..
Permeability \•fill primarily affect the design considerations of grout
curtains and cutoff walls, but usually wi11 not affect yenera1
arrangement.. It \oJi 11 also influence the grouting procedures, mixtures
and equipment \'Jh i ch wi 11 be used both on the surface and underground.
The erodibility, pipeability and dispersion characteristics of the
materials in the damsite are critical to the arrangement of the free-
board dike due to the dike location and the depth of overburde~
beneath it. Other areas \"ihere these characteristics are of concern
can be remedially treated and so will not normally affect arrange-
ment.
Seismic response and the effects of inundation are two operational
properties \~hich will have major impact on the desi~n of both surface
and subsurface structur~s. These properties are critical ~ri1narily
to the arrangement of the freeboard dike and major cuts.
Approach and Discussion
To obtain the types of data discussed ~nder 11 0bj ect i ves", a deta i 1 ed
design level investigation has been outlined. The investigation of
the abutments and underground areas is considered in two parts: geo-
logic features and civil features. Geologic features include the
major lithologic and structural features in the damsite~ Civil fea-
tures 1nclude all foundations, CdVerns, tunnels and spillways in the
damsite. These features ar,e listed in Table 2.2. The. geologic fea-
tures are discussed separately from the ci vi 1 structures because they
will be investigated not only for their effect on the design of civil
2-5
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structures, but also for the development of a geologic model of the
damsite. This model \'lill be used to predict geologic conditions at
depth and in other areas of scarce data.
The geotechnical factors discussed above will be determined, where
appropriate, for the geologic and civil structures. These factors
will be investigated by various methods: surface observations, drill-
ing, excavation, surface g_eophysics, downhole instrumentation and
downhole testing. Details of the methods are presented on Table 2.2,
which is a matrix of recommended geotechnical exploration methods
versus geologic and engineering features. The matrix shows the suit-
ability of the various exploration methods for a particular geologic
or civil feature.
(i) Geologic Features
Details of the geologic features in the damsite are presented
in the 1980-81 Geotechnical Report. In summary, the geologic
features in the damsite area include the major shear zones,
11 The Fins 11 and 11 Fingerbus:·er 11 , smaller damsite shears
(GF1-GF7), an alteration zone on the left abutment (GF8), and
the contact between the diorite pluton and the surrounding
country rock (Figure 2.2). These discontinuities were identi-
fied during feasibility investigations, but will require more
detailed study. Large scale mapping will be required for all
features except the pluton boundary, and will delineate surface
extent and character. Full survey control will be utilized in
critical areas.
Drilling wi 11 consist of probe holes, overburden sainpl ing and
rock coring. Core dri111~1g will be used to investigate fea-
tures to determine lithoiogy and extent of discontinuities.
Samples will be taken for in-situ material properties, and
overburden will be sampled for those features which 1 ie beneath
the dam foundation. Plug and probe holes will be drilled if
required.
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No extensive excavaticns are planned in the investigation of
geologic features. Test trenches may be dug across the ~amsite
shears and in the area of the alteration zone to determine con-
ditions of discontinuitie~, lithologic variations, weathering
and stability. Samples will be taken as required. All excava-
tions will be mapped in detail.
The components of a surface geophysical program are shown on
the footnotes to Table 2.2, and in further detail on Table 1.3.
The seismic refraction method has been used extensively on the
abutments of the damsite with good success. The primary area
for geophysical surveys will be on the left abutment alteration
zone and right abutment excavation areas to define extent,
overburden thickness, top of rock surface and bedrock quality.
Other :ieismic techniques will be used where appropriate ..
Permanent downhole instrumentation will be principally placed
in those geo.ogic features beneath the dam foundation" Therm-
istors and piezometers will be installed to monitor changes in
the physical environment of the abutments, and to provide
design data and construction monitoring of frost-thawing and
aggradation.
Downhole testing will be conducted on all features except the
pluton boundary. Testing methods, shown on Table 2.2~ \~ill be
used to collect data on the physical environment, in-situ pro-
perties and stresses, and extent of discontinuities as appro-
priate to each feature.
(ii) Civil Features
The types of civil features to be investigated in the damsite
area are listed in Table 2.2. The geotechnical investigation
will examine surface conditions for the main ~am, cofferdams,
freeboard dike and spilhvay foundation~ and suhsurface condi-
tions for underground features.
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Surface observations:. which include geologic mapping and photo
interpretation, will be used primarily for the main dam abutments.
Large scale detail mapping of geologic and geQoorph01ogic features
will be done using survey control. A 11 surface mapping for under-
ground features should be completed before the detailed feature
design phase begins.
Drilling will be done for all civil features, and includes subsur-
face drilling in test adi.ts. Plug/probe holes should be drilled for
all features except in the pm'lerhouse adit, to determine general
overburden thickness and rock quat'ity. Overburden samples will be
taken for 1 i thol ogic i dentifi cation, stability ana 1ysi s and material
properties tests. Sampling for subsurface features is recomme.nded
for the portal areas. Core drilling can recover rock samples to
identify surface and subsurfac~ discontinuities and depth of \'feath-
ering beneath the foundations. Samples wi 11 be taken v1here appro-
priate for laboratory testing. Bath plug/pr .. obe. holes and core holes
will be used for testing and instrumentation equipment installa-
tion.
·>
Excavations to exam1ne surface and subsurface geologic conditions
should be done for major surface foundations and underground fea-
tures. Test trenching can be done beneath the spillway and free-
board dikes to examine overburden and bedrock 1 ithalogy, permafrost
conditions, ~tleathering, stability, and erosion and piping potential.
It is recommended that test adits be excavated into the major
underground features to determine geotechnical conditions for design
of the underground structures~ and to develop efficient underground
design.
Seismic refraction surveys or other geophy 5 i ca 1 :netnods can be used
to determine overburden thickness, rock surface and rock quality.
Permanent down hole unstrurnentatian should be installed beneath all
major dam faundat ions and in the unrj'=rground features. Thermi star
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strings and piezometers will be installed in drill holes as
required to measure thermal and ground water conditions.
Inclinometers wil·1 be installed where necessary to evaluate
slope stability.
Down hole testing covers a wide range of geotechnical test
methods. Various tests have already been done at the damsite;
however, additional testing is recommended in the design phase
drill holes. Testing should be done _at the location of all
.
civil features to define the water and thermal characteristics,
rock and soil material properties, permectbility and operational
response properties.
(b) Damsite -River Area
Objectives
The objective of this part of the investigation will be to obtain the
necessary design level geotechnical data to finalize the general
arrangement and to establish construction costs and schedules for
Eivil foundations located within the active river floodplain. This
data will consist of the geology and engineering properties of the
bedrock and alluvium to determine the suitability of the material for
a dam foundation. The thickness and lithology of alluvium in selected
areas was examined during feasibility studies, which determined that,
due to lack of information at this stage, this material should be
assumed unsuitable for feasibility estimates. Design level studies
should expand these previous studies to examine the in-situ material
properties and operational properties of the alluvium to determine its
suitability as a foundation. Significant design, cost and schedul~~g
benefits may be realized if the alluvium proves suitcJble for founda-
tion use.
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The types of data to be acquired for the river area are shown on Table
2.1. The format of this table is rlescribed in the previous section
(2.2 (a)). The criticality of river area data is .primarily listed
under 11 Cofferdamsu on Table 2.1. The heading "Dam Foundation"
includes both the abutnents and the river area foundations. The geo-
technical factors for Hhich data collection is recommended are divided
into the follo~1ing categuries:. geologic, physical, geomorphologic~
in-situ properties and operational properties. The criticality of
design level data in these categories is discussed below.
Geologic factors include the lithology and discontinuities within the
bedrock and alluvium. These factors are necessary to the design of
the darn~ but are not critical to general arrangement· since unsuitable ..
material can be treated or renoved. Discontinuities should have no
effect on co.fferdam design.
The physical environment factors are the surface \·later, yround Hater
and thermal characteristics of the river area. These characteristics
may be used to deter111i ne if 1 eakage or sett 1 ement \'li 11 or cur under the
main dam or cofferdam foundations. Problems related to these factors
may be treated during construction and are primarily cost and scilt:ruu 1 e
related.
Geomorphologic factors include topography, Heathering and stability of
the materia 1 s beneath the river. The topography of the r·ock surface
may be critical to the arrangement if the surface is radically differ-
ent than anticipated, thereby affecting the dam dimensions. \·leathered
bedrock materia 1 requiri 19 remova 1 from the foundation \'JOUl d have a
significant cost and schedule influence only.
Topography and \veatheri ng are not critical to cofferdam arrangement.
Data on stabi 1 i ty re 1 ated problems is cri ti ca lly necessary to the
foundatio.l design and arrangement. The suitability of material
beneath the main and coffer dams is essential since it may not be
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removed, and so could affect overall dam excdvation levels~ and hence
overall space requirementse
The in-situ material properties of the r·ock and alluvium should be
supplemented by laboratory testing., ·These properties ~Jill ~enerally
affect design considerations of the main dam and.cofferdams. However,
the thickness of the alluvium could require a change in the
arrangement of the main dam if this material is to be removed.
Alluvial properties such as density, porosity, compressive strength,
dynamic strength, erodi~ility and pipeability are generally critical
to arrangement since this material may serve as the cofferdam
foundation.
Operational properties such as seismic response, effects of inunda-
tion, wave funnelling and thermal degradation will influence design
parameters \tith impact on general arrangement.
~
Approach and Discussion
The exploration methods for the river area should be designed to
supply adequate data to satisfy the requirements of the geotechnica 1
designs. The exploration methods are shovm on Table 2.2, which is a
matrix comparing geologic and civil features versus ex~loration
method. In section 2.2 (a), the geologic factors \·Jere presented in
terms of establishing a geologic model. Since thi~ has been described
previously, 1t will not be repeated here •. The effects of the geologic
factors will be presented here strictly in terms of their effects on
civil features.
Surface observations of the river area civil features should be com-
pleted prior to the design phase. Drilling activities should be
partially completed prior to design level activities. During the
design phase, the drilling program should continue with .alluvium samp-
ling and rock coring. These samples may be used for determining geo-
logic conditions and in-situ material properties. Drill holes will
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be used for downhole instrumentation and downhole testing where appro-
priate. Excavation in the river area should be done only where geo-
logic conditions warrant it.
Surface geophysical exploration should be completed prior to th~·.
design phase investigations.
. Permanent downhole instrumentation should be installed 1n selected
drill holes beneath the main dam and cofferdams. Thermistor strings
may be used to determine the thermal conditions within the alluvium
and bedrock. Piezometers should be installed as reouired.
'
Additional design level down hole testing shoula cc.nsist of a var'iety
of geotechnical methods to be performed in alluvfum and bedrock.
Recommended tests are shown on Table 2.2, and should be designed to
measure the water depths, permeability, seismic velocities, density
and moisture contents. Test results can be used for determining
in-situ material properties and operational properties, particularly
the. seismic response and effects of inundation.
(c) Relict Channels
.Objectives ·
The two identified relict channel areas at the ~~atana damsite (Figure
2.3) were discussed in depth in the 1980-81 Geotechni~al Report and
the particular poten":ial problem$ associated with these abandoned
river channels were discussed in the Feasibility Report. Basically,
the primary concerns regarding these areas are:
-Potential for excessive reservoir leakage of such magnitude as to
affect project economics;
-Potential for excessive flow gradients under reservoir head, which
might cause piping {internal erosion) of ·material and hence, induce
progressive failure of the reservoir confinement;
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Overburden instability or seismic liquefaction potential, v1hich
could result in breaching of the reservoir rim; and
-Crest sett 1 e.11ent due to saturation and per:nafrost tha1t1i ng.
The definition of present conditions and the development of a concep-
tual engineering model of the relict channels is necessary to provide
a determination of necessary remedial action or operational procedure
rules.
Approach
The definition of the relict channel conditions can be accomplished by
·dividing the investigation into a ser·{es of oarameters to be defined,
such as:
-Stratigraphy;
-Material Properties;
-Boundary conditions;
-Geohydrojogy;
-Permafrost conditions; and
-In-situ physical properties.
The progra•:l of investigations has been divided into tvto sta~1es anc.l may
include assessment of tile various parameters as sho~m on Table 2.3
-.~tage !-Fiscal Year 1983 (July 82-June 83)
.. ~age I investigations-will utilize limited seismic refraction sur-
veys to refine the Ha_tana f:,;;~l ict Channel confi,.;;uration data, anu to
assess the overali width and local gradients of the Fog Lakes Relict
Channel. Detailed stratigraphic ar:d materials sampling is planned
for the summer :'l~d winter phases in the Hatana channel, \'Jith a 1 im-
itea local borehole permeability testing program. Following co11ec ...
tion of the bc.:sic stratigraphy, hydr·Jlogy and boundary ccnd1tions!'(
the fina1 design phase Hould incorporate d det.ai1~\l i~vestigation
based on the results of the Stage I studies.
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-Stage II -Desi~Level Investigatio~
The deta i 1 ed investigation ~Ji 11 be p 1 an ned only after the ana 1ysi s~
of Stage I data~ Under ideal conditions, the Stage I studies could
remove all concerns about the relict channel areas. However, in all .,
likelihood, at least a limited design level and operation program
wi 11 be required. The recommended Stage I I program \'IOUld i ncl uae
the following activities, as detailed on Figure 2.4, dependent on
Stage I and progressive Stage II results:
-Stratigraphic borings, sampling and downhole geophysical logging;
-Large diameter material sampling borings, using both "disturbed"
and 11 Undistur·bed 11 sampling;
-Laboratory testing to evaluate sensitivity., pipeability and con-
. solidation properties;
-Field density and shear strength tests;
-Field permeability, piezometric testing;
-Field aquifer· flo~ tracingi
.. , Computer a qui fer mode 1 i ng;
~· Field thermal moni taring for permafrost, including recovery of
permafrost samples;
\:)
-Age determination for evaluation of stratigraphlc relationships; •
-Pump testing in large diameter wells; and
-Construction and operation of a floYI monitoring weir system at the
channel outlet area.
uiscussion
Tile specific potential problem areas are discussed belo~1.
.. Leakage requires knowledge of the hydraulic characte·ristics of the
channels) including bedrock profilei width, reservoir exposure,
gradient, transmissivity and stratigraphy. Hydraulic modellins
would probably be required to develop an understandlng of channel
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characteristics under operational conditions, utilizing piezometric
and flow characteristics under natural conditions to provic~ initial
cal ibrat·ion of the model.
Piping evaluation requires· the gradient and flow stratigraphy infor-
mation described above, plus detailed information .on the matel:"'ial
quantities and cohesion in the potential flow zones.
-Instab.il ity could ilivolve either reservoir rim slope stability pro-
blems, which requires geologic information and general soil strength
parameter data; and seismic instabi 1 ity potentia 1, which is depen-
dent on in-situ hydrostatic conditions and in-situ material proper-
ties. Analysis would be conducted on hypothetical failure modes
using data fr·om 11 Undistut~bed 11 sampling operations ..
-Settleme~+ could involve natural ~aterial response to saturation,
vJhich can be determined from undisturbed borehole sampling; or thaw-
ing of permafrost. In either case, systematic borings and sample
testing can be used to assess the potential magnitude of the problem
and to design any necessary remedial measures.
In general, the investigations for the relict channels require first
an assessment of potential parameters which could .be beyond acceptable
ranges, then progressively more sophisticated parametric testing and
ev~luation for those conditions which merit continued concern.. The
entire pr·ogram, in order to avoid excessive expense, must be a contin-
ual program of feedback of field and laboratory information into engi-
neering evaluation to assess the impact and potential resolution of
problem ar·eas encountered. An 1ndication of the range of potentially
significant parameters is shown on Table 2.3 .
(d) Impervious Bar~
Objectives
The current project general arrangement (Feasibility ~eport, 1982)
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ca 11 s for a cowpacted impervious till core in the t~atana dam. Because
of the cri~ical seismic conditions and permafrost environment at the
site, a number of generic material properties could be significant in
the Jesign or construction of the project. The full range of poten-
tially significant factors is indicated on Table 2.3, ranked by esti-
mated importance to general design activities. The major geotechnical
properties of significance are shown below:
-In-situ Borrow Site Properties
• Stratigraphy and a v ai 1 ab 1 e reserves
• Ground-water
• Permafrost
• Continuity of material properties
• Hoi sturE ·.::ontent
-Placement and Pr-ocessing Requirements
• Workability {plasticity, cohesion)
• Gradation (maximum particle size, piping protection)
~ Compaction properties (Proctor density)
• Consolidation, internal strength
-Operational Properties
• Seismic response {dynamic strength)
• Permeability, piping resistance, cracking behavior
• Surface frost penetration behavior
• Long term consolidation -
ApproacB
The potential dam impervious core material sources ~dentifit::.' in
previous stuaies have been designated as Borrow Sites D and H (Figure
2.3)~ Due to the site proximity and apparently better-drdined
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characi;er of Borrow Site D, it has been designated as the primary
source. All explorations will be concentrated there unless conditions
are found to be less desirable, in vlhich case, the type of program
planned for site 0, would be extended to Site H.
The planned progra1i1 ;-,corporates the same two-s·~age. investi9ations as
the Watana Relict Channel (Section 2.2 (c)), with the FY83 investiga-
tions being a consequence of the need for Re 1 i ct Channel i nft')rhla~ ion
will serve to simultaneously address, with additional lab testing~ the
major in-situ Borr0\'1 SiteD condition questions.· The specific ueo-
technica1 conditions to be tested or evaluated are indicated witt; an
approximate measure of significance, on Table 2.3.,
Discussion
The detailed sampling and testing procedures outlined on Table 2 .. 4 can
be used to varying levels of sophistication (Tt:tole l.i~) as required to
obtain the necessary desi yn data and construction procedure/cost esti-
mates. The special sampling and detection methods that are required
for design level investigations, will be controlled by the probable
critical parar.teters, \vhich are listPd below.
-In-situ Borr0\'1 Site Properties
• i'toi sture content and uniformity
• Permafrost ice content and temperature, which affects excavation
difficulty
• Ground water level and transmissivity, potentially affectir.g
bortmt pit operation
• Excavation area trafficabilit.y, which is d function of soil
strength and moisture
• Available reserves and stripping ratio, \'Jhich controls production
cost
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"" Pl acement and Processing Kequ irements
• On-fill transport, ra1s1ng and compaction equipment r2quirements
. Compaction density and strength
~ Gradation and internal coefficients
. Consolidation and triaxial strength
-Operational Properties
• Dynamic response behavior of the construction 111aterials after
dam, completion, which is a critical factor in the dam design,
and wil~ involve dynamic testing and simulations
. Core permeability and piping resistance, and the self-healing
characteristics in event of seismic 0r settlement fracturing,
which is critical to design considerations and will control
placement specifications in construction
. Post-construction behavior of the core face and crest area und~r
the influence of freezing winter temperatures, critical for
design considerations, but is not likely to result in signifi-
cant design or cost variations
. Long-term dam consolidation and creep performance, wh:tch may
affect the detailed design of the dam section and is ther-efore
significant even though the generai arrangement or overall cost
is not likely to be affected by these factors
In general, the specific boring information developed in pre-design
stages (including the FY -83 program) wi 11 have to be expanded on
larger scale samples through test pit op:rations and large-diameter
laboratorj' testing, with a, confirmation program in construction
entailing a test-fill and construction performanr;e monitoring.
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(e) 3ranular Borrow
Objectives
The objectives of the granular borrow investigations wil I be to iden-
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tify in sufficient de~ail and accuracy the availability, properties,
and cost of fill and aggregate mater~als for the various project uses.
The properties and quant1ties available r1u:·t be sufficient for antici-
pated construction needs, and of adequa\. · quality for the long-term
life applications proposed below.
Uam granular fi 11;
-Dam and auxiliary filters;
-Concrete ag:fregate;
-Asphaltic concrete aggregate;
-Gravel road surfacing;
-Road sub-base; and
-Camp structure base pads.
Approach
The investigations approach needs to assess a number of factors which
affect cost or usability of the materials for a specific use. The
parameters which migh~ affect a particular borrow site are listed on
Table 2.3.
Based on the investigations to date, three genera~ source areas have
been identified, as shown on Figure 2.3. These areas are Tsusena
Creek, the Susitna ~iver valley, and possibly the overburden in 8orrow
Site D. The explorations and data compilation programs will incor-
porate factors such as (,aul distance, elevation, material suitability
and adverse natural conditions. The particular exploration 111ethods
which might be expected to be u~ed are shown in Table 2.4.
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Discussion
There appears to be adequate quantities of granular borr0\'1 ;uateri a 1 in
the Watana area. Hm'lever ~ a number of factors which wi 11 strongly
influence suitability for various uses need to be assessed. Due to
the v-arying constraints on cost, vol urne required, and engineering pro-
perties limits, it ;nay result that different areas may be utilized for
different purposes. The primary factors are listed belm~:
-Transportatipn distance (haul costs);
Deposit configuration (controls size and hence economics of mining
equi pnent);
\!later table in borro\'J site (determines mining lilethod);
-Permafros~ (controls equipment selection, wastage, rehandle);
-Gradation;
-Percentage of fines, cohe~ive material (process1ng requirements);
-Elevation (centrals haul costs);
-Stream/river flood potential (affects risks of losin~g production,
access to site);
-Environmental factors such as vegetation, stream/river div~rsion
requirements, visual impact, siltation potential, and
-Materi 31 'fleatheri ng characteri sties.
In general, explorations to date have determined the material in
i3orrow Site E (Figure 2.3) as suitable. Therefore, utilization of
Sites F, I~ and J will depend on restraints on the use of E or limited
benefits in haul distance t~ tt0 usage pointn Risk analysis and
enviroP.mental factors may influence the final site selection, so the
geotechnical investigations need to anticipate this fact and evaluate
alternatives in sufficient detail to provide flexibility in ('"election
and contractor operations.
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the usage point. Risk analysis and environ,nental factors may influ-
ence the final site selection so the geotechnical investigations need
to anticipate this fact and evaluate alternatives in sufficient detail
to provide flexibility in selection and contractor operationso
(f) Rock Quarry
Objectives
The feasibility level design and estimate are based on all construe-<
tion materials being from the grat.u1ar borrm'l source-s (E, F~ 1, J,
Figure 2.3) with the only blasted rock use being for economic disposal
of waste rock frum excavations. Therefore, the investigations of
potential rock sources (Figure 2.3, Quarry Sites A, B, L) will be
li1nited to reconnaissance level work to ensure backup availability, ~f
needed.
Approach
Should a need or economic advantage develop for quarry rock produc-
tion, the full ranae of geotechnical explorations (Table 2.4) could be
applied to the potential quarry site. Under tile full development
plan, a series of critical factors could influence production and
usage plans:
-Type and breakage characteristics;
-~·Jeathering characteristics;
-Placement and compaction effort requirements;
-Placement and compaction durability, and
-l\s-bui 1 t strength and dynatili c behavior.
The design criteria ~ttould be developed through examination of roc:"
quality in place and by borings and laboratory testing~
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(g)
Discussion n
The three potential quarry sites which have been identified to date,
in addition to waste rock from excavations, could be utilized early in
construction as a readily available source of access road fill, or for
cofferdam construction. The investigations to date, which have been
limited to reconnaissance mapping and one set of weathering durability
tests now i.n progress indicate that Quarry Site B would be uneco-
nomical when compared to the other sites because of excessive over-
burden as the face retreats into the hillside. Site L, along the
river, was designated to provide a readily accessible quarry for the
critical cofferdam construction activities, if needed. Quarry Site A
appear·s to have adequate capacity for providing far more than any
anticipated demand for blasted rock. It is also in the most suitable
location for site construction.
The determination of quarry requirements, optimal source location, and
the economics of development will certainly control the anticipated
use of these sites and hence, the requirements for explorations and
geotechnical evaluation.
Reservo·\r
Objectives
The reservoir area 1s significant to geotechnical design in two areas:
slope stability and leakage p~tential. The objective of studies in
the reservoir area, exclusive of "Relict Channels", (Section 2.2 (c)),
would be as follows:
-Determine leakage potential to adjacent drainage;
Determine possible one-time reservoir filling losses in saturating
previously unsaturated areas;
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-Assess current active or historic slides to eva'luate potential for
activation or progressive reactivation, and to assess the potential
of adjacent similar areas failing;
-Assess the potential for new sliding or bank failu~es under the
influence of reservoir wetting or from fluctuating reservoir
levels;
-Assess the pote.ntial for significant turbidity deposit migration
from reservoir banks or riverbed deposits to the damsite which might
int~rfere with dam operation;
Assess the p~tent:ial for significant bank erosion and L~aching under
res~rvoir fluctuation, waves or ice action; and
-Assess the po~ential for adverse natural chemical contamination of
reservoir waters from contact with overburden or rock along the
reservoir.
Approach
The general approach to addressing these potential areas of concern
would be to evaluate the significant potential geotechnical parameters
controlling the physics of each condition, as outlined in Table 2.3.
The physical factors would be evaluated first by field reconnaissance
mapping to validate and expand on the initial reservoir mappintJ
(1980-81 Geotechnical Report). For those areas of potential concern,
soil sampling by hand and by air-transportable drill would be used to
obtain samples of the material. Laboratory testing of such samples
would provide the necessary design parameters. If areas of signifi·
cant slope or rock instability were encountared, an expanded drilling
program with piezometric and thermistor installation and monitoring
would be considered to further evaluate the potential for failure, and
other detailed investigations might be conducfed as outlined in Table
2. 4.
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Discussion
Uue to the great expanse of the reservoir area and the very signifi-
cant cost of explorations in the remote reservoir areas, a parametric
assessment of the benefit of exploration would be conducted. Recon-
naissance level surficial geology mapping would suffice for most envi-
ronmental, aesthetic and engineering assessments. Expansion to drill-
ing and instrumentation should be weighed against several factors
listed below, which might show expense to be excessive for the benefit
gained.
-Cost of remedial "cosmetic" repairs to eroded areas ver~us cost of
detailed, assessment of erosion potential.
-Cost of lost energy value potential in worst case versus cost of
-determining probable los5 due to leakage, reservoir bank retention
or bank creep into the reservoir area.
Cost of physical slide hazard removal versus cost of measuring and
monitoring potential slide area.
-Probability of damage to proje::~t features from a particular slide or
slope failure, as a function of dist1nce from the critical features.
The last two considerations are probably the most significant in terms
of cost, because the expense of drilling and instrumentation would be
significant for even minimal investigations. Most potential slide or
instability features would not be hazardous to operation or physical
facilities due to their distance from the damsite and could therefore
be deleted from consideration. Likewise, slide areas of significance,
if local or widely scattered in nature, could be intentionally removed
prior to pool fillirig in a controlled manner, at less cost than anal-
yzing and monitoring their condition. However, if recreational shore
and boating use of the reservoir is considered, th2 slope stability
question assumes a greater significance due to safety aspects. At
2-24
,,
~
•' !
·' ~
' J
~ ,.,
'I • tt-,,
r~
t~
:J
f'(i
' r1
hiJ
,. ,1 i
' ,,
t\t' ""-..
: l
.,\1.-~
\..;.._J'
.+.;t
e\ ,•l
Q:j
~· 't ,lr''
t1;
I J·~ l! ,,
~~ ~~
~JE .. ~
''f . .
~.,
• 4
•I ,
~~~«:
.
I ' o-,:J<
Me,¥
\
,j
I • li«
\.,~~
•. j
I• '-b.i
this time, no major hazard to any users or the project has been
detected, but investigations to an appropriate level of detail should
be conducted prior to commencement of reservoir filling.
(h) Auxiliary Facilities
Objectives
The Auxiliary Facilities grouping has been introduced to include such
support, maintenance, living and recreational facilities as may be
constructed and include the following types of features:
Site access roads;
Runways/airfields/helipads;
Construction camp;
Permanent operating personnel village;
-Shop/maintenance structures;
-Control buildings;
-Switchyard;
Water supply;
Waste disposal facilities (liquid, solid);
-Fuel storage; and
Visitor centers, campsites, recreational areas.
The investigations would be designed to provide the necessary geotech-
rdcal design parameters for siting and design of these structures.
Approach
The investigations programs for these features would be very similar
to that for an equivalent structure in any location. The geotechnical
factors which are considered potentially· signif1cant to these struc-
tures are listed on Table 2.3. Each type of structure, being of a
different use and design life, would be designed using the exploration
best suited to economically design the feature.
2-25
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Discussion
While the specific exploration methods which might be selected from
Table 2~4 might vary, the following general factors apply t0 all
structures and would be considered in each case:
-Foundation conditions;
"
-Ground water;
-Permafrost;
-Water quality;
-Inherent stability;
-Natural hazards (flood, slide debris flows) avalanche, rock falls,
icing, fire); and
Project-induced hazards; tflood, waves, bank sliding, rise in water
table, permafrost thawing, falls, machinery, roads, water releases)
to visitors/guests/residents.
2-26
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I TABLE 2.1: WATANA DAMSITE -GEOTECHNICAL PAi~AMETERS
I
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I DAM FREEBOARD MAIN HiERGENCY DIVERSION PQ\iER PONER POWER ACCESS · GEOTECHNICAL FACTOR . FOUNDATION DI}(E SPILLWAY SPILLWAY COFFERDAMS TUNNELS INTAKE TUNNELS CAVERNS TUNNELS
Gt0LG~£C:
lithology -Material Type 2 2 2 2 -2 2 2 2 2 -Material Oensitv 2 1 2 2 2 2 2 2 2 2 -Material Uniformity 2 1 2 2 2 2 2 2 2 2
I
Discontinuities -Shears 2 -2 2 -1 1 1 i 1 -Joints 2 -1 2 -1 2 2 1 2 -Contacts 2 2 2 I 2 -2 2 2 2 2 -Inclusions --2 --2 2 2 2 -
-
PHYSICAL:
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~later -Water Table 3 2 3 '3 2 2 3 3 2 3 -Aquifers, Flow Direct ion 2 2 2 2 2 2 -2 -2 -Surface Drainage 3 3 3 3 -3 -----Chemistry --3 .. -3 -3 3 3
I
Thermal -Temperature 2 2 2 3 3 2 l 2 2 2 -Ice filled Voids 3 2 3 3 3 3 } 3 3 3 -Conduct iv1ty, 2 2 --------Thermal Properties
I
I GEOMORPHOLOGY, WEATHERING:
Topography -Ground Surface 1 2 1 1 1 3 3 3 -3 -Rock Surface 1 2 1 1 2 1 1 2 2 2
Weath~ring -Weathering in Bedrock 3 -3 1 -1 1 3 -3 I
Stability -Rock 2 -1 2 2 1 1 1 1 1 -Overburden 3 3 3 1 3 3 3 ----Organic r~at 3 ----------Existing or Ancient 2 -1 2 2 1 2 1 -1 Slides
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. Reworked Stability -2 --2 ------Inundated Stabtlity 2 1 --1 1 1 ----Riverbed Materials 3 ---1 2 ----I
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. . ~. ~ ; :.~~ . ::·:." ·>
. -. : . . . : . . . : . ' . . : . . . . . ' ~ ~ . . . -,•
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DAM FREEBOARD HAIN EMERGENCY DIVERSION POWER POWER POWER ACCESS GEOTECHNICAL FACTOR FOUNDATION DIKE SPILLWAY SPILLWAY COFTERDAH!: TUNNELS INTAKE TUNNELS CAVERNS TUNNELS
IN-SITU MATERIAL PROPERTIES:
Rock -Density 2 -2 z -2 2 2 2 ... .: -Corrpressive Strength 2 -2 2. 2 2 2 2 2. 2 -fensi le Strength --2 --2 2 2 2 2 -Shear Strength 2 -2 - -
2 2 2 2 2 -Modulus .,. 2 -z --2 2 2: 2 2 -Effect of Wettmg 2 -2 z -2. 2 ? -· -c.
Borrow Material, OverL .... ·den
-Density -1 --1 ------Voids, Porosity -1 --1 ------Compressive Strength -1 --1 ------Shear Strength -2. --2 -.. ----f.1odulus -2 --2 ------Compressibility -1 --2 .... ~ ----Noisture -2 ---------Thickness 1 2 3 3 2 3 3 J -3
Permeability, Groutability
3 2 3 -Shears, fractures 3 -3 -2 z 2 -Stratified Overburden -2 --2 ---- -
Erodability 1 pipeability, dlspersion 2 1 2 2 1 2 --- -charactet".:istics .
OPERATIONAL RESPONSES: I
Seismic 2 ., 2 J 2 2 2 2 2 2 2 -I
i -Repeated inundation 2 1 --~ 2 2 •. 2 -- --Repeated wave action 2 2 -2 2 ~· -----Thermal effect on permafrost 2 2 --------I
LEGEND: 1 -Critical t..., design. Adverse condition could affect feasibility of current. general arrangement to extent of changinq overall fea~ure location or
design. t.Jusually involves overall stability or support problem, or potential failure from applied project or seismic effects. Inherently
implies cost significance.
2 =further information needed to provide values or l'efined criteria asStJnptions for use in developmf'r"! of deta).Jnd design. Usually involves Hems
of strength, erodability, topography that can be solved through design without major changes in g~neral arrangement. Generally incluo""'S all
structural factors. Inherently includes cost significance.
3 = Factors that could be expected to signt f~cant ly affect· only canst ruct:.ion costs, schedule or quantity estimates 1 and therefore> might d1ct-ate
design changes or feature relocation for cost rather than funct ]anal or structural considera~ ions.
... .
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I TABLE 2.2: h1ATANA OAMSITE -GEOTECHNICAL EXPLORATION RECOMHE'NDATIONS
I SURfACE OBSERVATION DRILLING EXCAVATION PERMANENT DONN HOLE INSTRUMENTATION DOWN HOLE TESTING
PLUG/ OVERBUIWEN lt.~l
MAPPING. PHOTOGRAPHY PROBE SAt.PLING CORE TRENCH
fEATURE -CIVIL (1) (2) ( J) (4) (5) (6)
Main. Dam -Rlver P,S P,S s P,S P,S N I
-Abutments P,S,O P,S,D D D P,D Q
I Cofferdams s s P,S P,S P,S N
Diversion Tunnels 5 s D N 0 N
Intake Structure s s D 0 D
Penstocks s 5 D N 0 N i
Powerhouse N N N N P,D N
Surge fl\amber N N D N [). N I
Tailraces s s D 0 D N
Access Tunnels s 5 D D 0 N I
Outlet Control s s 0 0 D Q
I Hain Spillway s s 0 D D D
Plunge Pool P,D s D D Q N
I Emergency Spillway s s D S,D D D
freeboard Dike s s P,S,O P,S,D Q 0
Site Roads D D D P 11 D q
II
P,D [;
Camp/VIllage D D P,D P,O N D I
-I LEGEND: C ::: Completed
N = Not likely to be appropriate
Q .::. Questionable -will be revised only if geologic conditions warrant. use
I NOTES: Dos1gn Level lnvesti;:~at ions Est-!mate -Watana
Categories inc 1 ude fo Bowing mc.thods/techno 1 ogy:
1.
l.t.!:ll/t'll
BLAST
(7)
N
"'J
N
0
N
N
N
N
N
N
N
Q
N
Q
a
Q
I N
l:Al!::i~ljN/
SHAFT ~DIT
(8) (9)
a N
Q 0
a N
N D
N N
N Q
Q D
Q D
a D
N D
N N
N N
N N
N N
Q N
N N
N N
SURFACE
GEOPHYSICS THER~HSTOR PIEZmlETF:H lNCLINOHETER
(10) (11) (12) (13)
P,S D a N
P,S P,D P,D a
P,S 0 Q N
s D 0 Q
s Q D 0
Q D D N
0 I N P,D D N
N D D N
N D D Q
5 0 D Q.
s a D Q
s P,Q 0 I Q I
(
5 N N N
D a D N
c P,S P,S Q
Q a 0 N
'· D, D D N
I
D = Scheduled for design level investigations
P = Partially completed in previous explorat-ions
S = Schedule· for fY83 explorations
WAitK !:it!~. tC
LEVEL PERMEABILITY VELOCITY
(14) (15) (1$)
P,O P,O D
P,D P,D 0
P,D P,D Q
0 0 0
0 D D
0 D D
P,O P,D D
D D D
D 0 0
D D 0
I 0 D D
D 0 D
I
I N N I' Q
I
Q Q Q
P,S P,D Q
0 Q N
D 0 N
-
I 2.
J.
All levels of on-the-ground geologic mapping.
Controlled and uncontrolled vertical and cbli.que aerial photography, and low 1blique to horuontal surface photoqraphy, wlth associat-ed qeo;oqic:/geomorpholoqic inl~t'preration and'lllap preparation.
Rotary, auger, percussion, wash borin·g and jetting type holes in whi,:h only tha cuttings are s<:!mpled. Used to detect stratigraphic variations and rock surface.
All types of drilling in which dehberate sampl tng is c0nducled l·"'dudlng hoUow stem, sprial fli'ght or bucket auger, reverse circulation, churn, corir.q 1 spoon, and tube sampling.
Diamond, carbide, and calyx core recovery methods. Also includes reverse circulation 11 air lift 11 type coring methods.
4.
5:.
I 6.
7.
8.
9.
10.
I
11.
1Z.
l3.
Trenches or blocks excavated to provide linear exposure by means of hand shovel, saw, backhoet dozer, drag1 ine, etc.
Pits and face exposures produced by bulk excavation with dozer, backhoe, or explosives on a larqer scale than (6) to check bulk homogenity and )n depth of material properties.
All forms of deep vertical excavation to allow in-place inspection of materials. Inclues hand-dug, clamshell, and large diameter bucket auger/calyx operations.
Rock excavation to gain access for in-place deep underground rock mechanics testing and m-silu. geologic evaluation.
Surface geophysics includes all of the following methode listed in approxi111a! e order of probability of use on t.he project:
-Seism1c refradion -Seisr.-ic reflection
-Resistivity -Sonar/sonic profiling
-t-tagnetomet er -Grnv imeter
1hermlslor strings, thermal probe standpipes; both permanent down hole instrunent and lf'ltermittent reading manual systems.
Standpipe, pnellllatic, and electric systems. . . . . .
CANER A
( 17)
0
0
0
0
0
D
0
0
D
D
0
0
N
Q
0
N
N I
I 14 ..
15.
16.
I
Any type of bore hole deformat1on or dtsplacement devtce includ1ng "slope 1nd1cator" type instrunent.s and extensometers, deforrnomet·ers.
filly means of w:-1 er level detection prinr to h~Jle completion; manual "plunki'"':gn, ah lift, ''M-Cope" or piezometer.
Any comtlinat ion of all permeabilib and aquifer tests including packer tests and open hole tr-sts f>uch as falling, constant, or rising head and pump tP'3ts, and cross-;Jole aquifer tracing by dye or radtonuclide.
Both s1ngle-point seismic shear or uptt wave, and cross-hole seismic.
17 ..
18.
19.
20o
I
oot'e hole camera 1 video, al:'ousl.:ic proflhng.
tJuclear and vJdeo, acoustic prornmg.
All types of plat~ or rad1al jackmg, dllatometer, duecl shear, bulb, and lShear wave tests.
Oriented jack.mg, overcoring, c:iosed tunnel pressur.e tests, and hydrofracturing.
Dt.NS l TY
HOI STURE
(1R)
S ,D
D
s,o
D
D
D
0
0
D
D
D
D
Q
D
P,S,D
P,D
D
I
IN-~.l ~-u
NODULUS ST?E:S~
(19} czr·
0 'll
D (?
0 ~.
0 c
D a
D Q
D t
D Q'
D jJ
0 a
a ~ t.-
Q c:
N ~
~ N.
0 \lc ,.
~ 1\i.
~ 'U
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GEOTECHNICAL FACTOR -
GEOLOGIC:
Lithology -Material Type
-Matenal Densitv
-Material Uniforr'itity
Oiscont muit ies -Shears
-Joints -Contacts
-Inclusions
PHYSICAL:
Water -Water Table
-Aquifers, Flow Direction
-Surface Drainage
-Olemistry
Thermal -Temperature -Ice Filled Voids
-Conductivity, Thermal Properties
GEOf-lP~PHOLOGY, WEATHERING:
Topography -Ground Surface -Rock Surface
Weathering -Weathermg in Bedrock
Stab.il ity -Rock -OverburdPn
-Organic Mat -Ex 1sting or Ancient Slides -Reworked Stability -Inundated St.ab.i 1 H y -Riverbed Materials
..
TABLE 2.3: WAl'ANI ~ELATED AREAS -GEOTECHNICAL PARAMETERS ..
RELICT CHANNELS I!w!PERYIOUS GRANt:! AR CONCRETE ROCK 11m T ANA _.!:_ Uli _AKtc!:':l BORROW fiLL BOl1RO\~ AGGREGATE QUARRY RESERVOIR
2 2 3 3 2 2 4 1 1 -· 3 ---1 1 3 3 3 3 4
2 2 ---3 ------2 -2 2 2 3 -2 ... ----2 3 -
'
2 2 3 3 3 J 4 2 2 3 3 3 3 4 --I 3 3 3 3 4 4 4 4 4 4 4 4
2 2 2 3 3 3 4 1 1 3 --3 4 --2 ----
~
2 2 3 3 3 --2 2 3 3 3 3 2
-----3 -----f --2 1 1 3 J 3 3 2,4 2,4 4 4 4 4 -4 2 2 3,4 3,4 3,4 3,4 2,4 2,4 -4 4 4 4 -1,4 1,4 4 4 4 -1,4 -~----4
SITE ACCESS CAI-P MISC. AUX. ROADS RUNWAY FACIL IT!ES FACILITIES
2 ---2 £ ---2 --2 2 2
----2 --2 --------
2 2 2 I 3 --4 4 3 3 3 3 --4 4 I
2 -2 2 3 2 2 2 -2 2 2
0 3 3 3 -3 2 . -2
----
2 ---2,4 2 -6. 4 2,4 2,4 4 2 ---2 2 2 -2 --2,4 ----
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· '\BLE 2.3 (Cont 'd)
..
' RELICT CHANNELS It-PERVIOUS GRANULAR CONCRETE ROCK SiTE ACCESS CA~ MISC. AUX. GEOTECHNICAL FACTOR _!t~l\I~A t Uli. U<\Kt.:> BORROW fiLL BORROW AGGREGATE QUARRY RESERVOIR ROADS RUNWAY FACiliTIES fACILITIES
~1ATERIAL PROPERTIES: -.
In-S1tu -Lithology 2 2 2 2 2 2 4 -2 2 --Uniformity 2 2 3 3 3 3 --2 2 --Laterial Extent 2 2. 3 3 ) 3 --2 2 --Vertical Extent 2 2 3 3 3 3 --2 2 ---Densitv 1 1 2 --2 --2 2 2 -Moistute 2 2 2 ----2 2 2 2 -CompresSlbility 2 2 -----2 2 2 2 -Vo1ds 2 2 ----.. -2 2 2 -Permeability 2 2 2 ---2 -2 2 r 2 Processabil ity 1 1 1 2 . 2 --------Wastage, Reserves --2 2 2 2 --2 ---
CONSTRUCTION PLACE~ENT PROPERTIES:
LEGEND:
-Compaction - -
1 1 -2 ..
l
2 2 --Moisture --1 2 --.. 2 2 2 -Camp ressib i llt y I - -
2 2 -2 -2. 2 I --Weathering Resistance --2 2 1 2 .. ----Unrformity --) 3 3 "S -., 3 3
-Gradation --2 2 2 I 2 I -2 2 2 -frost Susceptibility --2 2 1 2 -2 2 2 -Concrete Reactivity ----1 ----2
1 = Critical to design. Adverse c!lndition could a.ffect feasibility of 'current general arrangement tc extent of changing overall feat.ure location or designo
involves overall stability or s_upport problem, or potential fai lur.e from applied project or seismic effects. Inherently implies cost significance.
-----
2
2
-
Usually
2 = further information needed to provide values or refine<t criteria assurrptions fm· ust> in ··cf':!velopment of detailed desJ.gn. Usually involves 1tems of strength~
erodability, topography that can be solved through design without major changes in general arrangement. G~neral1y 1ncludes all structural faders .. Inherently
includes cost significance.,
3 =Factors that could be expected to significantly affect only construction costs, schedule or quantit-y estimat~s, and therefore miqht dictate design changes or feature
relocat.ion for cost rather than functional or structural cons1derations.
4 ;: Features or items that demand aUent ion for development of & model of site condJtions for use in environmental, general project development or public affairs issues ..
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SURfACE OBSERVATION
MAPPING PHOTOGRAPH'
t"LUl?t
PROBE
FEATURE (1) (2) (3)
GEOLOGIC:
Watana Relict Channel 5 s P,.s
fog Lakes Relict 5 5 Q
Channel
"The finstt P,S,D P,S Q
"f:i ngerbust er" P,S,O P,S Q
L.A. Alterat1on Zone S,D s Q
Dams]te Shears P,S,D P,S D
Pluton Boundary P,S P,S Q
Reservoir Stability D D N
MATERIAL SOURCES:
lilflervious P,S P,S P,S
Granular P,S P,s P,D
Rock P,S,D P,D D
LEGEND: C : Cor..1pleted
0 : Scheduled for design level in~restigations
N = Not likely to be appropriate
-
DRilLING
UVt.Kt$Ut<Ut.N lt..SI
SAWLING CORE TRENCH
{4) (5) (6)
P,s,o 5 N
0 N N
Q D Q(D)
Q P,O Q(O)
D P.,D D
D P,D D
Q D Q
D N N
P,S,D P,S P,D
P,S,D N P,D
D D N
P = Partlal1y cOillp!eted 1n previous explorations
Q =Questionable-will be required only if geologic condition~ warrant
S : Scheou1ea for FY83 explorations . .
use ..
NOTE: For footnotes 1 through 20 see Table ?. .. 2
· TABLE 2.4: WATANA RELATED ARE,\5 -GEOTECHNICAl EXPLORATION RECOMMENDATIONS
.·
EXCAVATION i PERMANENT DOWN HOLE' INSTRUMENTATION DOWN HOLE TESTING
It.!> 1/1-' ll L:A.l!::l!::lUN/ SURFACE WAltJ{ . :JI:.l~IHC DE..NS!IY L.l'..l.~.J.IU BLAST SHAFT ADIT GEOPHYSICS THERMISTOR PIEZOHETER INCLINOMETER LEVEL PERMEABILITY VELOCITY CAMERA MOISTURE MODULUS srmrss (7) (8} (9) (10) (11) (12) (13) (14) (15) (16) {17) (18) (19} (7,...1\ ......;-...o.. j .
N Q N P,S P,S P,S Q P,S S,D 0 N P,S N ~
N Q N P,S,D a D 0 0 0 Q N D N ~ ..
~~ N Q P,S N Q N 0 D D 0 N 0 "'t:r
N N Q P,S N 0 N P,D P,D 0 D N D C'
N N N P,D D P.,D N P,D P,O 0 Q N Q y\ *"·
N N Q P,S P,D P,O N P,D P,D D P,D N P,n ~)
N N Q P,S N N N N Q Q Q N D tt.
N N N Q D 0 D D a N N D t<: ~
I
----·
D Q N P,1 P,S P,s N P,S N D N P,S N ~'
D Q N P,Q 5 P,S N P,S N D N P,s N tt·
0 N. N D D D N D N D Q N· N ~
"'
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H 3,225,000' ~-...
"'" ... ------·
/
/
/
1-
1
. \
'l-·4_:..-
j ~
~--> ~~
V" ---.-·"·-./" i --~·
l ... /
ACCESS
iii ____ .,.. ..... ----..... ---·---------i_
! -----,
..
; CREST OF DA 1 EL. 2210 If _,---.,.. i. ~ / .... '-----'
: ---·~
TAr ,.11 }·•RACE · ,..,•,INEL
WATANA
GENERAL ARRANGEMENT
--_. ........... __ ~
·---""~"--
ACCESS TUNNEL
bOWNSTREAM :;::;:c-:~.t:::'l··~~:::::::~~~~-PORTALS .
-. //· . . ... .) 1
NOTES:
l GENERAL SEE fEA ARRANGEMENT DETAlLS. SIBILITY REPORT ~~~ENERALtZE:Z SPEClFi:
0 200
SCALE ·~~~5iiiiiii.;4~00 fEET
FIGURE 2J
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-
.. •'
/
• • ... l
o'J ~~. ,.'Z:,'·. f
•.
SCALE
~~ORITE TO QUART A NOR GRANOOIO:.T~ORiiE. INCLtr::-"
NOESI1'E POR ---~ MINO~ DACITl~Jin', INCL~E:S ~ DIORITE
0
U.Ti)'l;£.
. PORPHYRY
CONTACTS~
--145 LITHO -DIP vfOGIC, DASHED STRUCTURE; HERE I(NOWN WiitRE INFERRE::.
r-····
L._l
SHEAR WIDTH VERTICAL UNLE~~EATER' niAN lQ p==-
SHEAR, WIDTH DIP S.."!C'I't" --•
INCLINED LESS nt!." KNOWN • VERTICAL EXii:E 10 FEE"'" • u .... loT WHEl?"'
FRACTURE -10 FEET. V ZONE, WIDTH • ERTICAL ut•• GREATER TW'
I
FORAFCTURE ZON"' , .... ESS DIP SIK'n~ .
E"'T IN ... , Wt"'-H t. ' WHERf: 'I<NrMNEO, vf.frri:~S Ttt.l.'<
JOINTS' N EXTe,-
VERTic:Al_NCLINEO OPEN EXCEPT Fl SETS 't AS~ , ~S:CLINEt:' C1 OPEN ,-::...~~C'i.:.Y, ' .... _ ' s}
ALTERATION """~ric~ SHOW"!' ZONE, wm;
OTHER:
.o. WJ-1 JOINT STATION
GEOLOGIC FEATURE
FEET
DETAILS 0 lN 198 F GEO..-OGIC F£A' O-81 GEO...,ECHNIC ;nm!'s PRES~-=-At. Rt;.PORT. • ' _, ..
FIGURE 2.l2
-' ' ... : . . ~ ; . . ' : :.. . \ . . ·.. . ~ :. _; . . . , .... · ... ..: . . . . ·~ . , . . .. : '\ . . . .
..
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WATANA
BORROW SITE MAP
.. *;.jt·· ~----4 ,~~~-
0';??-" r ,_........ ' · . .... ..,.,_ (~~-"'(. i ........
j t~:~ --~-~ ~ '
,;::<;<\." ~-·--~i"::_.,---, ~-_.w';:,_1~ .... . ' ~... ;;'~--. ~--~
0
LOCATION MAP SCALE [
------~----------------------------~~----
LEGEND . c:: =:1 BORROW I QUARRY LIMITS
NOTES:
I. DETAILS OF BORROW SITES PRESENTED itt
1980-81 GEOTECHNICAL REP<CRT.
FIGURE 2.5
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3 -DESIGN LEVEL l:iEOTECHNICAL INVESTIGATION~ -DEVIL CANYON
3 .. 1 -Program Development
"'
Tht~ D~v i 1 Canyon deve 1 opment is schedu 1 ed ~ under the current over a 11 project
schedule!~ to lag behind Watana by approximately 9 years, Since it is unlikely
that further geotechnical investigations wi 11 be conducted at the Devil Canyon
site during the 1982-84 period, a detailed Devil Canyon geotechnical program has
not been developed in this report.
For simplicity and coherence in the geotechnical program development, the Devil
Canyon activities have. been broken out into the same eight areas as at Watana,
and area listed below. Each of the areas has been defined in relation to the
Feasibility ~eport General Arrangement, a simplified version of which is pre-
sented in Figure 3.1.
-Damsite -Abutments and Underground~ which includes all power generation and
flow regulation facilities, underground structures and tunnels, and spillway
facil'ities .. This classification also includes main dam thrust blocks and the
left abutment saddle darn.
-Damsite-River Area, including all foundation and cofferdam areas within the
active floodplain, grout curtain and cofferdam cutoff areas, and the spillway
plunge pool areas. It also includes adequate upstream and downstream coverage
of areas which might be excavated for diversion or tunnel outlet channel
training.
r -Relict Channel -which at the Devil Canyon site is limited to the depression
which is planned as the saddle dam constructior areau This feature also
bounds the left abutment thrust block, and intercepts the discharge area of
the emergency spillway.
3-1
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-Imperyioats Borrow Sources, which has not been identified in proximity to the
site~ While the quantity of core material required for the saddle dam is not
excessive, at the feasibility level no local source was locatedi so the esti-
. mate assumed a very long haul from the Watana borrow site.
-Granular Fill and Aggregate Sources, which to date include Borrow Site G, im-
mediately upstream of the dam at river level; and possible use of excavated
material from the saddle dam area.
-Rock Quarry Sites, which to date include possible use of excavated material
from the spillway and thrust block areas and from required underground and dam
foundation excavation; and a designated "ijuarry K" approximately a mile south
of the damsite.
-R~servoir containment and operational stability, including potential for water
loss, slope failures3 and environmental consequences of geotechliical behavior
under reservoir operational conditions.
-Auxiliary Facilities, which include construction and permanent living, sup-
port, and maintenance faci~ ties; switchyard structures; and recreational and
associated non-op.erational facilities ..
Because thP. scope of this report does not entail development of specific program
recommendations, an outline format has been adopted to note the major factors or
areas of concern, without expansion to the detail presented in the Watana sec-
fion. While specific geotechnical parameters and exploration method tables have
not been produced, the factors and procedures presented on Tables 2.1 through
2.4 would apply equally to the Devil Canyon site~ although with variances in the
criticality and priorities.
3.2 -Des.ign Level Geotechnical Investigations -Uevil Canyon
(a) Damsite -Abutments and Underground
Objective
The objective of the design phase ~eotechnical investigation of the
3-2
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abu~nents and underground areas should be to define the surface and
subsurface conditions for the location of the main dam and saddle
dam foundations, and t.: e location and orientation of tunnels and
caverns {Figure 3.1) •. The investigation objectives should be based
on known geologica; features identified during previous studies
(Figure 3.2) and other potential adverse conditions Hhich may be
found. A detailed discussion of the site geology is presented in
the 1980-81 Geotechnical Report. In summary, known geolog·(c fea·-
tures ··nclude discontinuities such as northedst trending dikes
(Hl-;14 and F1-F8), and shear z.ones (GFl-GFll), open joints on the ..
left abutment and bedding plane foliation, which may effect the
stability of the foundation and subsurface features, and an apparent
bedrock lo'll beneath Borrow Site G of unknown origin (Figure 3.3).
An east-west trending shear zone (GFl) lies beneath the saddle dam-
site, as \'lell as thick overburden conditions \·thich may dllo'r't leakage
or settlement beneath this structure.
To meet the design requirements of this site, a detailed list of
geotechnical factors to be studied must be assembled as was done for
the Watana site (see Section 2.2 and Table 2.1). Tne geotechn1cal
factors include geologic conditions, physical environment, geomor-
phologic conditions, in-situ material properties and operational
properties. These factors should be considered \~here appropriate
for d~n and spillway foundations underground tunnels and caverns,
and the numerous auxi 1 i ary construction features.
Appr~ach and Discussion
The required geotechnical data discussed above and in Table 2.1 must
be obtained through a c6mprehensive exploration program. This pro-
gram, as at the vJatana site (Section 2.2a), should be comprised of
an investigation of gec 1 ogic features both for a geologic model of
the site, as well as for their effects on civil features Table 2.2
show~ the exploration metnods reco~nended fi ~he Watana site.
3 ... 3
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Similar techniques will be used for the Devil Canyon explorations.
These techniques and the geotechnical factors for which they should
be used are discussed below.
Surface observations will be conducted for all civil features to map
in 1 arger scale the 1 ithology _nd discontinuities, topography,
weathering, and slope stability at the sites.
Drilling activities will consist of plug/probe holes, overburden
sampling and rock coring. -Plug or probe holes will be usea for
determining overburden thickness, top of bedrock surface and bedrock
quality, as well as for installation of down hole instrumentation
and for down hole testing. Overburden and rock samples will be
taken for determining lithology and in-situ material properties.
Overburden samples may be necessary primarily in the relict channel
beneath the saddle dam area (Figure 3.2). Rock coring will be done
across shears and dikes on both abutments of the main dam, as well
as across feature GF-1 beneath to saddle dam.
Exploratory excavations will be planned across geologic features to
determine lithologic extent of discontinuities, topography, weather-
ing, and stability. Test trenches or pits will be most jppropriate
for surface structures such as the intake, spillways, 1 eft abutment
thrust block, and saddle dam foundation. Shafts and/or adits \vill
be used for the underground features where design parameters are
critical to cost or support design.
Surface geophy~ics includes a variety of techniques listed on Tables
1. 3 and 2. 2 These methods will be used where appropriate to deter-
mine the extent of discontinuities, overburden thickness, bearock
topography, and weathering. Surveys will be done.in the area of the
bedrock low, across snear GFl, along the spillways and dam abut-
ments, and for underground features, particularly in the portal
areas.
3.-4
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Permanent down hole instrumentation wil1 be installed to monitDr the
physical environment and slope stability. Thermistor strings and
piezometers wi 11 be used where appropt~f ate beneath surf ace features
and in underground areas to determine thermal conditions and ground
water, res~ectively. Inclinometers may be installed if necessary.
Down hole test methods are listed on Tables 1.3 and 2.2. These are
recommended for determining water level, aquifers, permafrost,
weathering in bedrock, stability, in-situ material properties, and
operational properties for all features as approprjate.
(b) Damsite -River Area
Objective
The objectives of the design phase geotechnical investigation of the
river area will be to define the subsurface conditions beneath the
main dam and cofferd~~ foundations. This includes determining the
properties and thickness of alluvium, and defining bedrock discon~
tinuities and weathering. The investigation objectives will be
based on known geological features identified during previous
studies (Figure 1.1) and pote\ltial conditions which may be found.
Known geologic features include northeast trending dikes (Ml-M4 and
Fl-F8) and shear zones (GFl-GFll) mapped on the abutments (Figure
3.2), and bedding plane foliation which may affect stability and
leakage beneath the foundation. Potential conditions to be antici-
pated may be the presence of an east-west trending shea-r_, simi 1 ar to
GFl, beneath the river, and unfavorable alluvial material beneath
the cofferdams which may affect groutability and foundation stabil-
ity.
To me:.c:t the design requirements~ detailed geotechnical data must be
obtained. A list of the recommended geotechnical factors to be
studied was assembled for the Watana site (Table 2.1), and is dis-
cussed in Section 2.2 and listed in Table 2.1. These factors
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include geologic conditions, physical environment, geomorphologic
conditions, in-situ material properties and operational response
properties ..
Approach and Discussion
The required geotechnical data discussed above and in Table 2.1 may
be obtained through a comprehensive exploration program. Table 2e2
shows the exploration methods recommended for the river area at the
Watana site. Similar techniques will be used for the Devil Canyon
explorations~ These ~echniques and the geotechnical factors for ..
which they should be used are discussed belcw.
Surface observations for river area features were essentially com-
pleted during prior explorations.
Drilling activities in the river area will be used to determine
alluvial thickness, bedrock surface, lithology and discontinuities,
and down hole testng and instrument installation. Samples will be
taken for in-situ material properties tests. Drilling will be done
at both cofferdam !ocatio~s and beneath the river through bedrock
between the abutments.
Detailed structural explorations in the river area may consist of
caissons in alluvium of the cofferdam area, and an adit beneath the
river to determine lithology, discontinu,Jties, weathering, stabil-
ity, and rock mechanics properties.
Surface geophysics may not be practicable in the r1ver area due to
high water velocities. Permanent down hole instrumentation and
testing will be done to determine the thermal environment, in-situ
material properties and operational properties of the ailuvium and
bedrock.
3-6
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(c) Relict Channels
Objective
The objective of investigations of Relict Channels in the Devil
C~nyon Reservoir will be twofold. The first, which is explained in
detail under Section 2.2(c) for the Watana site, relates to water
tightness and potential reservoir rim instability. The second,
which applies only to the Devil Canyon damsite, is the engineering
stability of the relict channel which occupies the saddle damsite,
which is significant to the actual damsite arrangements and saddle
dam design.
ApprGach and Discussion
To date, no evidence of potential leakage or rim instability prob-
lems has been detected. While a more thorough field reconnaissance
is required, the fact that a vast majority of the reservoir area is
exposed igneous or metamorphic rock reduces the risk, and makes
slope stability a less significant p~onlem. The question of block
rock-slide failure will require additional in-depth study, but the
evaluaton :;f reservoir sta')ility and water-tightness is expected to
be straight forward and definitive.
The saddle dam relict channel was identified in the initial site re-
connaissance investigations, and has therefore been considered
throughout the p~eliminary arrangement studies. The issues at ques-
tion which need resolution in the design studies are listed below,
and relate to the dam arrangement and cross-section shown in Figures-
3.1 and 3.3.
-Alluvial depth;
-Allivium bearing capacity with depth;
-Seismic response and stability of al1uvium if used for saddle dam;
-Permeabi1ity of alluvium if used for foundatinn;
3-7
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-Rock permeability under saddle dam area;
-Alluvium erodability an~ bedrock surface between the saddle dam-
site and the valley which the emergency spillway is designed to
empty intos which is significant under any final design arrange-
ment with the current emergency spillway location, but is particu-
larly critical if the downstream shell of the saddle dam were to
be designed to rest on the a 11 uv i urn rather than on bedrock; and
(J -Depth of weathering in the rock unde·r the saddle damsite, which
will be a function of the geologic history of the channel.
In summary, the currently available information on the reservoir
stability and saddle dam relict channel indicate that whil~ more
detailed studies are needed, the results of the studies are likely
to influence only project costs, rather than arrangement; and then
only in a beneficial manner since preliminary design was based on
conservative assumptions.
(d) Impervious Borrow Sources
Objective
The objective of the impervious borrow studies will be to locate a
more economic and suitable source of impervious or semipervious
material for the Devil Canyon development. The current planning
assumed trucking material from the Watana damsite, because 0f a lack
of suitable material in the Devil Canyon vicinity.
Approach and Discussion
The only anticipated use of imper·vious material at this time is for
saddle dam, cofferdam, and emergency spillway fuse plug core mate-
rial. The continued search for suitable material will be based on
the assessment of several different alternative designs, which could
3-8
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. (e)
tolerate varying quality of materials in the structures. Alterna-
tives of artificially crushed or bentonite-m"xtures material manu-
factured into a suitable c~teria1, concrete or metal faced or core
structures, and various pervious core alternatives. may be looked at
to determine tradeoff economics. Geotechnically, four alternatives
~
\t/Ould be investigated in detail to assess the potential for cost
reductions:
-Selective fine enhancement of natural local matt:rial by crushing
or screening;
-Production of suitable material by direct crushing qf available
rock;
-Selective mining and blending of locally available source
materials; and
-Importation of materials by rail fro.n a till or lacustrine deposit
downstream of the damsite.
In all cases, the .effect of the impervious borrow studies must be
contra 11 ed by the potential economics of targeted schemes prior to
investigation, to ensure that any possible scheme Hould result in a
cost savings over the present alternative. Hhile the availability
of suitable matsrial might affect the design of the various earth-
fill darns proper, it is not likely to result in general drran9ement
changes, and hence, is not a design critical function.
Granular Fill and Aggregate Sources
Ob~ective
The granular borr0\'1 investigations have the goal of ldentifyiny ade-
quate reserves of material in suitable quality and at reasonabl~
cost for the following uses:
-Concrete aggregate and sand,
-Grout and shotcrete aggregate and sand;
3-9
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-Construction roads and pads -subgrade
·-wearing surface (grave 1)
-aggregate {concrete)
-Camp/village pads and footin·gs;
-Filter material; and
-Dam shells, as required by design criteria.
Approach and Discussion .'
The investigations to date have identified two source areas for
granular borrow; the saddle ddm excavation and relict channel area,
and Borrow Site G immediately upstream of the damsite (Figure 3.1).
The suitability of the material for all uses must continue to be
investigated to assure that it satisfies the same criteria as de-
tailed in Section 2.2(e) for Watana. A-critical cost factor is the
suitability of the saddle dam.area material without excessive pro-
cessing cost, and the geotechnical factors listed in Table 2.3 apply
equally to the lJevi 1 Canyon clams ite.
A critical schedule and cost function is the overall project devel-
opment schedule, because the use of Borrow Site G depends on a
diversion scheme which does not significantly elevate the river.
Therefore, the diversion tunnel size and the availability of Watana
damsite regulation is critical to the project. In order to assess
the impact of these factors, detailed reserve and suitability block-
ing will be required.
(f) Rock Quarry Sites
Objectiye
The investigation for rock quarry materia'1 will be directed at pro-
viding adequate construction rock and riprap for use in:
3-10
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-"Construction roads;
-Construction pads;
-Dam she ll,s (cofferdam, saddle dam);
-Slope erosion protection; and
-Concrete· aggregate:
Approach and Discussion
The level of investigations which may be performed will depend
totally on the anticipated demand for blasted rock materials. The
factors influencing cost and the exploration methods which might be
utilized·are comparable to those listed in Tables 2.3 and 2.4.
The preliminary reconnaissance and sampling indicates that reserves
and general rock qua 1 ity wi 11 not be a concern, so once· reserves and
performance suitability ar~ confirmed, emphasis would be placed on
the economics of production and particular suitability for each
app 1 i cation.
(g) Reservoir
0
Objective
The reservoir safety and economics depenu on a number of factors, as
listed below, and can be assessed in terms of risk and anticipated
damage, which then controls the level of remedial or preventive
measures to be taken in design and construction.
-Water tightness;
-Overburden stability;
-Rock stability;
-Bedload/sediment behavior;
-Environmental restraints;
-Seismic response;
-Reservoir fluctuation and wave response; and
Icing and wave erosion.
3-11
", ;{. :· ·:. -~ -. ·. •. ·.~ .:· ·~ ... ~::··:.~:: .
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The objective of reservoir geotechnical assessment wo: oe to
adequately answer questions and addv~ss in design the following
issues:
-Water retention;
-Damsite safety;
-Recreational safety;
-Environmental damage/impact;
-Operational restraints.
Approach and Discussion
The approach to the reservoir studies would consider the same fac-
tors as those listed in Table 2.3, and for the same reasons as
s~ated for the Watana ~eservoir (Section 2.2(g]), so no specific
discussion will be presented here.
(h) Auxiliary Facilities
Because both the Watana and Devil Canyon projects incorporate the same aux ..
iliary features, there is no need to duplicate the discussion in this
section.
3-12
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N3,221,000
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\ -~ . }
'"-----._/ I
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g ~
t ~ g
w w
I,)UARRY SiTE K ~I MILE SOUTH l I
I /1 I l ~I .--'
1 ) . y• E~~GEN.C'l' SPILLW.A
~~----------~FU$EPLUG /
I' 'EL l465.5 .,, './ .'
(/ EL 1434 /1. . ..__ ------------+--/4---.._
~ \\' I '··
DEVIL CANYON
GENERAL ARRANGEMENT
.'
NOTES·.
I. GENERAL ARRA.NGn!E~T iS
GENERALIZED. SEE ~e? l;:su=<~~lT··
REPORT FOR SFE:;::'-'~0:: tiETA~~.:.
0~~~2~0~0;;;;;?;4~00 FEET SCALE F ~
FIGURE 3.1
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:
'-.. ,,.
::::::·-·,>~
.
f <
{
"> '\. • • >
BORROW SITE G
oc-i\
t.
< '
REFERENCE' BASE IMP FROM RaM, 19$1 -t•,.z~::l'
li£V1L CANYO!i i()I>OGRAPH't.
COORDINATES IN FEE1',.ALASKA STAlE PLANE (ZONE 4)
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r /-,.f
DEVIL CANYON
GEOL061 C MAP
•:
. ,_,_ --·-~--
·-
• _,, • ., ·-"<-· "'' ............ _,~~ ..... .
--~-..-.. -... -.. __. __ ,
.,
LEGEND
LITHOLOGY:
LJ OVERBUR&EN, UNDIFFERE~{iEA':'£0
CJ ARGILLITE .AND GRAYWACKE OUTCROP
r""71 Ff;!.SIC DIKE, WIDTH SHO'<IN WHERE GREA'ffi'l'
L., • ....2.,j THAN 10 FEET
r~-;, MAFIC DIKE, WIDTH SHOWN! WHERE GREA-re::;·
L"ll!__j THAN lO FEET
·CONTACTS:
----LIMIT OF OUTCROP
STRUCTURE:
~·-, SHtAR, WIDTH SHOWN. WHtilt GF\EATER T"rf'-!1,
L._,_j 10 FEET, VERTICAL UNLES.$ t)IP SHOw!'.
OTHER:
'DC-I
t..t
.;\OCJ·t
(§)
Ml
Fl
SHEAR, WIDTH LESS THA'\ W FEET, IN;:~ Ut~;
VERTICAL, EXTENT WH£R:2 ~NOV.N
FRACTURE 'ZONE, WIDTH S!i~WN WHE=:t
GREATC:R THAN 10 FEET • VERTICAL U~E;::
DIP SHOWN
JOINTS, INCl.INED, OPEN l!'iCU:.0£0, VERne;:.:..
t SETS l AND II ONLY l
e:::oDJNG/FOLIATlON,II'!CU:.••'RI. VERTICAL.
GEOLOGIC SECTION LOCATION
JOINT STATION
GE(~ bGIC FEt.t URE
MAFIC DIKE
FELSIC DIKE
NOTES
t. CONTOUR INTERVAL .50 FEU
2. EXTENT OF SHEARS, FRACTUR.~ ~ONES AND
ALTERATION ZONES ARE INF£~~;:1) BASED CN
GEOLOGIC MAPPllfG AND SU~FA~:!:: l:XPLORAT!C~S:.
AND ARE SUBJECT TO VEIM'c~~'HON THROu;;'+
FUTURE DETAILED INVESTIGA":' .;:-!\$
3. DETAILS OF GEOLOGIC FEACUR~~ l>"lESEfjTEC
IN 1980·81 GEOTECHNICAL RE~*l
0~~~20~?~;,;-;;;~ 4~~0 FEET
SCALE £_. '""'
FIGURE 3~2
;, !
LEGEND
LITHOLOGY: c:m. OVERS\JROEN, UNOIFFERENTIATE:D
c=J ARGILLITE AND GRAYWACKE
~ INFERRED ORIENTATION OF BEDOING/ ~ fOLIATION, APPARENT DIP WHERE NOTED
R;:'~:;,m FE\..SIC DIKE, WIDTH SHOWN WHERE
~!:.::::..1 GREATER THAN 10 FEET
{"""•""""11 MAFIC DIKE.~ WIDTH SHOWN WHERE
1--_._J GREAT!;R TMAN 10 FEET
CONIACTS:
-----APPROXiMATE TOP OF ROCK
---LITHOLOGIC, DASHED WHERE INFERRED
ST.RUCTURE!
r-·---, SHEAR, W:OTH SHOWN WtiERE GREATER L.__i THAN 10 FEET
,....-... ~ FRACTURE ZD_NE_. W1DTH SHOWN WHERE L.;...:J GREATER THAN 10 FEET
GEOPHYSICAL SURVEYS:.
i" sW-!5 lllTE.RSECTIQN WITH SEISMIC REF.RACTION
LINE
sw -IS 1978, SHANNON a WILSON
SL80-13 1980, WOODWARD-CLYDE CONSULTANTS
SL81-2Z 198l,WOOOWARD-CLYD£ CO~'SULTANTS
SE.ISMIC VElOCITY CHANGE
~~~ SEISMJC VELOCITY IN FEET PER SECOND
BOREHOLES: SWl
LITHOLOGY~· •. l ! • FRACTURE
t
1
ZONE ~
. S• SHEAR
DH-1 USSR DIAMOND CORE BORING
8 H • I AAI DIAMOtiO CORE BORING
AH • Gl AAI AUGER HOLE
OTHER:
DC-I~
@)
Ml
Fl
NOTES
INTERSECTION WITH GEOLOGIC
SECTION DC-I
GEOLOGIC FEATURE
MAFIC O!KE
FELSIC DIKE
SECTICN lOCATION SHQ•,tS \.IN FIGURE 3.2
2. VERTICAl. 6 HORIZC!'!TAL SCALES EQUAL.
3.. SURFACE PROFILE .FROM 1"','2001
TOPOGRAPHY, RBM,l981.
4. EXPLORATION LOGS AND SEISMIC LINE Sa:TIONS
SHOWN IN I9B0-81 GEOTECHNICAL REPORT.
5. EXTENT OF SHEI!JRS, FRACTURE ZONES. AND
ALTERATION ZONES ARE INFERRED BASED ON
GEOLOGIC MAPPING AND SUBSURFACE
EXPL.ORAT!ONS,ANDARESUBJECT TO VERlflCATION
THROUGH FUTURE DETAILED ltWESTIGATIONS.
------'-'-·-.:........:.:. .. ..:....:....:.--,...;;... ....... -..,.;..---~---"""------------.....
1500
:z
0
~ > t1J
..l
I>J
500L
POWERHOUSE, TRANSFORMER GALI.E:RY
8. SURGE CHAMBER
PROJECTED 390' E Access
TUNNEL--c::J
.... ..... ,. -..: __ _
MAIN SPILLWAY
APPROACH
CHANNEL
/; :/ ~~· I 11 I 'l-'J!~·---~
/; I
;/ I ·; . . ~/, ~ /j: . FELSIC UlKE
BOTTOM
PROJECTED I 190'W
1!4
oc......-AZIMUTH -..p..lSO"
· · · OF SECTION
LOOKING UPSTREAM
CREST OF MAIN DAM EL.I46:31
OEVl L CANYON
GEOLOGIC SECTION DC-3
TtiRUST .. i..._T-OPEN JOINT
BLOCK ;I,._ f ~~MAFIC DIKE
BOTTOM
PRt'JE;;Ttll
250'W
BOTTOM
PROJECTED
280'W
0 100
SCALi:: . _ £
~~-~T
:;
BOTTOM
PROJECTED
15'E
-$·
FIGURE 3.3
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4 -ACCESS ROUTES
4.1 -Program Development
For progr~n seeping, the following breakdown of geotechnical investigation cate-
gories has been used:
-Route alignment;
• -Bridge locations;
-Slope/cut stability and hazard analysis;
-Subgrade conditions; and
Borrow materials.
Because the current construction schedule calls for delaying access road con-
struction until after r:'eceipt of the FERC license, the exploration activities
may not fall in the time frame covered by this report. Therefore, only a brief
checklist format presentation has been made which lists the major geotechnical
considerations which would need consideration in the design phase.
4.2 -P~ogram Scoee
Objective
The random of geotechnical factors given in the "Approach .. section .belo~1 is
intended as a general guideline of the major factors ~t.Jhich ar'e readily
apparent as potential influences on access road design or costs, and is not
·intended to be an outline of all factors to be considered in the detailed
design activities. The general geotechnical factors needing consideration
are generally the same as for 11 Site Access", and are listed in detail in
Table 2.3,. and the exploration methods \'lhich could be utilized to conduct
data collection are presented in Table 2o4.
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Approach
(a) Route Ali 9.D.!~ent
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General suitability of geologic conditions·over varying adjustments
in alignment within the selected corridor;
-Potential mass geologic effect on route;
Potential gross reservoir operating effect on route segments near
reservoir rim; and
-General seismic loading enviromnent.
(b) Bridge Locations
-~J\i nimum safe c 1 earance for future river of slide m~anders, grov1th !I
bank collapse or erosion;
-Potential for mass wasting or deposition at bridge site or nearby,
causing flow div~rsion or blockage;
-Foundation adequacy under design loads;
• Hydraulic;
• Geostat ic;
• Seismic;
• Construction loads (oath during bridge construction and loads
being carried by bridge during construction of the project);
-Evaluation of alternate bridge types for bridge site,
-Specific site selectioni and
-Site remedia"l measure requirements.
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(c) SlQQ~Cut Stability and Hazard Analysis
-Rock/land slides, talus slides;
-Creep of rocks or soil~ including solifluction and rock glacier
movement;
-Avalanche;
-Flood,
-Seismic -(direct motion of structure, foundation/footiny
collapse, induced slide/avalanche hazard); and
~ Reservoir bank erosion/wave hazard.
(d) Subgrade Conditions
(e)
-Bearing capacity;
-Long-term consolidation/creep;.
-Overburden slope stability;
-Ground water seepage/blockage;
-Per·mafrost, especially f·ree ice;
-Organics in soil, peat~ moss, etc.
Frost susceptibility; and
.. Seismic stability, especially liquefaction •.
Borrow fviaterial s -
-Weathering resistance;
Hat:1 c ··tance;
Cor,·, . ·c. suitabi1ity; and
-~~ear··. · ·, t.Jrface durabi 1 ity;
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5 -TRANSMISSION
5.1 -Program Development
For the purposes of program seeping, the transmission facillties geotechnical
investigations have been broken into the following major areas of concern:
-Route Alignment;
-ivlajor Crossings;
-Hazard Analyses;
-Tower Foundation; and
-Substat ions/S\·Iitchyards ..
Each \vriteup has been developed to address the major geotechnical areas of
concern or design activity and does not present all exhaust the parameters \~hich
would be considered in final design. While the general parameters \'lhich might
be considered are the same as on Table 2.3., the development of specific scope
and recommendations is not \'lithin the scope of this report because the current
-construction schedule places commencement of transmission line beyond 1984.
5.2 -Program Scope
Objective
~Jhi 1 e the deve 1 opnent of a specific program of proposed exp 1 oration
is beyond the time frame encompassed in this report, a general
rundown of the major parameter~ has been developed below, in
checklist format. Each major factor, along with its various
r~nJfications and associated criteria, would be evaluated to an
ade~uate extent for design, with provision for construction phase
confirmation \~here the factor i~ not: critical to design and can more
economically be handled in construction. The general conditions and
geotechnical philosophy, as described in Section 4.2 preceeding,
apply to transmission studies as welle
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Approach
Major factors to consider in design studies:
(a) Route Alignment
-Geotechnical influence on span lengths;
-Seismic response on alternative adjustments; and
Access road right-of-\·Jay stability.
(b) ri\ajor Crossings
-Ninimum safe clearance from natural features being crossed;
Long-span guying and add~tional support requirements;
-Long-span versus suspended conduit type structure foundation
di ffi cul ties;
-Geotechnical stability of feature being crossed ~probability of
river meandering, slide area extending to adjace ': areas,
et~., ); and
-Foundation adequacy to handle line pulling loads to cross
obstacle.
(c) Hazard Analysis
-Rocki1ands1ides;
-Creep;
-Avalanche;
-Flood and5
-Seismic-direct motion, foundations collapse, slides/avalanche
hazard.
{d) Tower Foundation
-Soi 1 depth, stratigraphy,
-Soil strength/b~aring capacity, depth to bearin~ layer,
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-Deformation characteristics;
-Anchor pu 11 out· resistance;
-Sci 1/rock \veatheri ng potentia 1;
-Stability under loading;
-Chemically corrosive conditions;
-Electrical grounding resistivity;
-Permafrost;
-Water table;
-Frost heave potential;
-Concrete borrow material locations; and
• Alternative foundation designs, with test loadingse
(e) Substations/Switchyards
-Soi1 depth, stratigraphy;
-Bearing capacity, depth to bearing 1 ayer,
-Deformation/consolidation properties;
-Stability under load;
-Seismic response;
-Corrosive condition;
-Electrical grounding resistivity;
-Permafrost;
-\~ater table;
-Frost heave potential;
-Concrete/road borro1;1 materia 1 l a cations;
-Footing/pad alternative designs and;
-Access facilities foundations stability.
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