ENGINEERING GEOLOGY

operation of the feature and also the issues' impacton the cost of the design, construction, and operationand maintenance. Critical issues should be emphasizedto make certain they are thoroughly scrutinized andevaluated.

.Collection of data;

.Collation, analysis, and interpretation of data;and

.Preparation of findings.

ENGINEERING GEOLOG,y EVALUATIONS

Throughout the entire process of arriving at a deci-sion or conclusion, the engineering geologist must ex-ercise sound judgment. A discussion of each issue andits evaluation, including the data required to reachthe conclusion should be documented in the "Geo-technical Considerations" portions of any geologic re-port. The amount of detail of the discussion of allyissue generally will depend upon its criticality and thetype of the engineering geology report under prep-aration. Individual discussion of each issue will ensurethat relevant issues have been identified and ad-dressed, are subsequently given proper considerationfor design concepts and constructability, and are ap-propriately monitored during construction andoperation.

The impact of the geologic considerations and theirspecific issues upon the propo~ied engineering worksmust be evaluated throughout the engineering geol-ogy program. Conclusions, decisions, and recommen-dations to address these issues must be providedduring interim data submittals and in the final engi-neering geology report. To accomplish this, those rel-evant geologic issues which must be addressed duringthe engineering geology progr:im must be identified.A convenient way to approach the identification andselection of issues is to consider :separately the geologicconsiderations groups on a site'-by-site and structure-by-structure basis. This should be done by: (I) refer-ring to the checklist of common issues in chapter 6;(2) discussing the program with involved parties; (3)seeking the assistance of experienced engineering ge-ologists and other professionals; and (4) reviewing andstudying similar case histories.

BIBLIOGRAPHY

[ 1] Glossary of Geology, American Geological Institutethird edition, American Geological Institute, FallsChurch, VA., 1987, page 788.

The issues should be categorized as to their relativeimportance for a safe and economical design, proper

4

ENGINEERING GEOLOGY

3. Document the investigatjion program on theACER Field Exploration JR.equest form;

4. Prepare transmittal memorandums;

5. Inform other representatiives of field inquiriesand of any actions taken. .'This may require dis-cussion and decisions by the group;

6. Monitor the exploration program;

7. Prepare memorandums Dlodifying original in-vestigation program; and

8. Assure that data reports are distributed.

Other members of the team are responsible for no-tifying the coordinator of any inquiries, discussions,problems, or information received from fieldpersonnel.

The initial meeting of the Exploration Team shouldbe held at the feature site. It is highly desirable thatthe team meet at the site with field geologists andmaterials specialists who will be performing the in-vestigations before the 'program is formulated. It isvery important that the investigation program be sys-tematically thought out and rationalized. For this rea-son "on-the-spot" or hastily derived investigationsprograms should be avoided. Prior to this meeting,the field geologist should have become very familiarwith the site geology and antici,pated geologic designand construction consideration:s. Much of the initialexploration program will be based on the field geol-ogist's knowledge of local geologic conditions. It canbe of great value if the field geologist prepares a pre-liminary or recommended explolration program basedon his knowledge of the area. It is recommended thatthe preliminary program be distributed to Explora-tion Team members prior to the site visit. The pro-gram should attempt to answc~r both geologic andgeotechnical concerns. Although the program maynot be used in its entirety, it doe~i offer a starting point.By the time the program is finalized, the ExplorationTeam should be able to justify fully all aspects of theprogram. Additional coordinat:ion meetings will beheld as necessary during progr.~ss of the program toresolve problems and make required modifications.

following programs require much thought and dis-cussion. A phased program is usually the most efficientand economical. The rationale for any explorationshould be documented so that all understand the useand value of the data. The TDP requires a TechnicalMemorandum (formerly the Engineering Geology Re-view Memorandum) to document these data andknown conditions. Additional exploration should bedependent on the results of the earlier explorationsand any corresponding changes in design concepts. Itis very important that the field geologist have full in-put into any stage of the exploration program andthat he or she concur by initialling (or authorizingtheir initials) on the fInal program, as concurring, onBureau of Reclamation Form 7-2145, "ACER FieldExploration Request." It should be emphasized thatthe team geologists' responsibilities do not end afterformulation of the initial exploration program.

Most schedules are based on political decisions andare certainly budget oriented. Therefore, our datacollection mayor may not be allowed adequate timefor the amount of data specifically required. The Ex-ploration Team must make a reasonable evaluation oftime required to collect these data and make the nec-essary adjustments that will accommodate both theproject and the Denver Office. Team members mustrealize that .commitments should be met, and theyshould not make a commitment that can't be met.

If scheduling problems arise, they should be referredto the PMT. This team has the authority to addressschedule changes or reduce the program. They alsorealize that when a program is reduced, the degreeof risk increases.

Other important duties of the field geologist, as amember of the Exploration Team, include the sub-mittal of interim data, interpretation of data, com-municating schedule or program problems andcompletion, recommending modifications to the ex-ploration program, and preparation of the GeologicDesign Data Report. The Geologic Design Data Re-port serves to document the data collection and re-suits. These data can be adjusted and supplementedas needed. Just how these data are to be formulatedand used should be clearly defined prior to issuanceof the ACER Field Exploration Request.

INTERPRETIVE GEOLOGIC DATA ANDPRESENTATION IN REPORTS AND

SPECIFICATIONSThe goal of the exploratory or investigation programis to prioritize and produce the amount of data re-quired for that level of study or design. These dataare to be obtained in the most efficient manner andat an economical cost. The team then transforms thesedata into a report or the specifications in the mostefficient manner possible.

In an effort to improve the overall quality of Bureauof Reclamation specifications and reduce constructionchanges and claims, the Total Design Process calls forthe inclusion of geologic information that conveysboth the known and anticipated geologic conditions.To accomplish this, accurate and timely data and inter-pretations of these data must be presented. Design

No attempt should be made to formulate an all-inclu-sive fiml program while in the field. The initial and

6

ENGINEERING GEOLOGY

Table 3-1. -Geologic Milestones and Responsibility.

IIII NoneNO WORK

1 1

11 NoneSched

START

! Exploration Team Members.II: Principal Geologist with team: approval.: Field Geologist.: Field Geologist with approval

i by Principal Geologist.! Principal Geologist.

TM (Technical Memorandum)

ACER Field Exploration Request(s)I: Prelimiinary Ongoing Submittals! Geolog~c Design Data Report(s)

Concept

i Geologic Design Data Review: Memorandum(s): Engineering Geology Considerations for! Conceptual Design TM

: Principal Geologist.IIIIICONCEPTC

Field Geologist.

Principal Geologist.Design

: Final {;eologic Design Data Report! Geologic Design Data Review: Memorandum: Draft Engineering Geology Considerations: for Design and Construction TMI

Principal Geologist.

DESIGNCII

! Field Geologist.

Draft

Spec i Principal Geologist.: Principal Geologist.I

! Supple'ments to Geologic Design Data

: Report: Specifications Paragraphs and Drawings: Final Jt:ngineering Geology Considerations! for Design and Construction TM

SPECD

Principal and Field Geologists.I I! ! Revie\'1' spec paragraphs and drawings

I IReviewREVIEWC

II: Principal Geologist.II Geology Division/Branch! Chief.

Review of Specifications

Specifications Drawings and ParagraphsSigned through Approved (anytimefrom SPECD to SPECB)

Revise

SPECB

: Geologic Requirements During: Construction Memorandum(at least: two months prior to AWARDC)

III

Book

pre! Principal Geologist.

BOOKC

8

ENGINEERING GEOLOGY

Table 3-2. -Required Action by Geologic Staff.

Flags

and

stages

Action required by Geology

II

! None officially. However, if geologic map of feature is not available, field geologist could start: mapping if approximate alignment or location is shown. Also, compile, review, and: summarize available data.I

NO WORK

Field geologist provides scheduling information to Project Management Team. Site mapping,data revielfi.Sched

START

Concept

Ii Site mapping and preliminary interpretations. Field geologist proposes explorations.: Design and Exploration Teams formed.: Site visit(s).: Geologic exploration program(s) developed and ACER Exploration Request(s) and TM: completed.! Geologic exploration program monitored, revised, or added to.: Periodic formal or informal data submittals.: Interim geologic data reviewed and provided to design team.: Geologic Design Data Report submitted, reviewed, and approved.i Documentation of geologic design and construction considerations (TM).

CONCEPTC! Geologic exploration program monitored and revised as necessary.I Identification of additional data needs.

Design i Geologic Design Data Report supplemented (if required).i Geologic datcl reviewed, additional analysis.i Input to design concepts and parameters.! Documentation of geologic design and construction considerations (Draft TM).IDESIGNC II1 Prepare spec paragraphs and drawings. Finalize geologic design and: constructi,on considerations.: Furnish spec paragraphs and drawing to coordinating design branch.: Signed through technical approval.II

SPECG* ~SPECD~ ,

Review

DraftSpec

! Review spec paragraphs and drawings; review all paragraphs, not just geology.

REVI

Final

Spec

Revise specifications paragraphs and drawings if necessary.Agree upon geologic requirements during construction.

SPECB

Book-Pre :Supplements to specifications.:Document geologic requirements for construction.1

BOOKC

10

EWC

ENGINEERING GEOLOGY

as aerial mapping done by Federal agencies, primarilywithin U .5. Department of the Interior. A similar of-fice is operated by the U .5. Department of Agricul-ture in Salt Lake City, Utah. Several other sources arereferenced in the Engineering Geology Field Manual,with annotations as to coverage, including NationalOceanic and Atmospheric Administration (NOAA),the National Archives, Bureau of Land Management,and the Remote Sensing Section (D-1542), DenverOffice.

Directories

A partial list of directories such as Directory of GeoscienceDepartments, Worldwide Directory of National Earth-Sci-ence Agencies, Information Resources in the United States-Geosciences and Oceanography, Industrial Research Labo-ratories, Government Research Centers Directory, andGeothermal World Directory, provides information aboutlocating names and addresses to use as contact points.

Data Centers Computer data bases

Other specialized data centers can be accessed. Theseinclude the National Geophysical and Solar- Terres-trial Data Center for earthquake data, Goodyear Aer-ospace Corporation, Side Look.ing Airborne Radar(SLAR) Imagery Depository, and the Defense Map-ping Agency.

These machine-readable files index several thousandjournals, books, conference papers, dissertations,maps, government publications, and technical reports.While the primary data bases for geologic informa-tion, such as GEOREF and GEOARCHIVE, shouldbe accessed, many other data bases contain relevantinformation and should not be overlooked, such asNTIS, COMPENDEX, TRIS, NWWA, and Disser-tation Abstracts.

Public Utility Companies

These companies may retain studies done during sitefeasibility investigations. The Directory of Electric util-ities is a good source of addresses for these companies.

METHODS OF TAPPING THESESOURCE~i

By allowing keyword searching, accessing titles, ab-stracts, and indexing terms, this method of searchingis both more comprehensive and more efficient thanmanual searching.

Libraries SUMMARY

Most of the materials discussec( in this chapter areavailable in libraries. Give special attention to uniquecollections such as the Bureau of Reclamation, USGS,Corps of Engineers, State libraries, university sources,and the depository system. U sing interlibrary loan toaccess materials not available lacally can expand thegeologist's scope considerably.

The geologist who makes efficient use of these exist-ing data sources will be in a better position to makegood use of his field time. Tables which list contactpoints, such as those for State geological surveys andFe.deral agencies, will speed up the information gath-enng process.

14

ENGINEERING GEOLOGY

4. Response to natural surface and near-surfaceprocesses (e.g., raveling, gullying, mass movement).

I. Bedrock units.- Traceab..~ geologic units ofsimilar physical and engineering properties shouldbe identified as described, including:

OTHER PERTINENT DATAa. Identification as to rock type (e.g., granite,sandstone, mica schist). Relative age and, wherepossible, correlation with named formations.

Include laboratory determinations of engineeringproperties of surficial deposits and bedrock.

b. Physical characteristics (e.g., color; texture;grain size; nature of stratification, bedding, fol-iation or schistosity; hardness; and chemical fea-tures such as calcareous or siliceous cementation;concretions, mineral deposits, alteration otherthan weathering).

Provide black and white photographs of representa-tive or particular geologic conditions, all drill holecore, samples, and test pits and color photographs ortransparencies if appropriate or desired.

Summarize data from remote sensing and geophysicalsurveys (seismic, resistivity), if performed and cOrre-late with other geologic information.c. Distribution and dimensional characteristics

(e.g., thickness, outcrop breadth, areal extent).Run appropriate borehole geophysical logs in drillholes and other appropriate surveys to delineate sub-surface conditions.

2. Distribution and extent of weathering and al-~~!!Q!!:-Weathering should. be divided into cat-egones that reflect definable physical changes inthe rock mass due to weathering. Significant dif-ferences should be identified and weathering pro-files developed.

Describe past, present, and possible future petroleum,water, and mineral extraction operations in the

vicinity.

Describe investigations undertaken to ascertain geo-logic conditions which may affect construction meth-ods such as boulders, marshes, drilling conditions,stability of grout or footing holes, ground tempera-tures, and gases.

3. Structural features.-Bedding joints, foliationjoints, joints, contacts, shear and fault zones, folds,zones of contortion or crushing are to be describedin terms of the following:

a. Occurrence and distribution.

Map land uses, particularly along linear features suchas canals, transmission lines, distribution systems, andhighways.

b. Orientation and changes in attitude.

c. Dimensional characteristics (e.g., width, spac-ing, continuity). Corrosion surveys should be considered for all Rec-

lalrn\.tion distribution systems, including pipelines, aq-ueducts, discharge lines, and siphons, in addition topower /pumping plants and tunnels.

d. Physical characteristics and their effect uponthe rock mass (describe the conditions of planarsurfaces, such as openness, roughness, wavinessof surfaces, striations, mineralization, alteration,and infillings or healing).

GROUND-WATER DATA COLLECTION

To describe investigations of ground-water conditions,note seeps, water levels or piezometric surfaces andrecord their seasonal fluctuation, the occurrence ofunconfined and confined aquifers, potential seepage,water-producing capabilities, chemistry, and groundsubsidence. The following checklist may be useful asa general guide for descriptions:

e. Statistical evaluations of distribution, orien-tation, and physical characteristics.

f. Relative ages (where pertinent).

g. Specific features of shears or faults (e.g., de-scription of composition of the fault, zones ofgouge and breccia, healing, displacement direc-tions and amounts, attitude of striations or slick-ensides, relative age of movement( s ]).

I. Distribution, occurrence, and relationship to to-pography (e.g., streams, ponds, swamps, springs,seeps, subsurface basins).

h. Prepare accurate and complete logs of explo-rations using terminology consistent with thenarratives (Chapters 4 and 5 of PI, EGFM). Giveconsideration to appropriate indexes (e.g., RQDtRock Quality Designation], Hardness).

2. Existence of confined and unconfined aquifersand relationship to geologic features (e.g., imper-vious and pervious strata, fractures, faults).

3. Recharge sources and permanence.

16