ML010510162

Draft Regulatory Guide DG-1101 (Proposed Revision 2 of Regulatory Guide 1.132), Site Investigations for Foundations of Nuclear Power Plants.

ML010510162
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Issue date:	02/28/2001
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O5REG(* U.S. NUCLEAR REGULATORY COMMISSION February 2001 OFFICE OF NUCLEAR REGULATORY RESEARCH Division 1 0 -Draft DG-1 101 DRAFT REGULATORY GUIDE

_ ***___Contact: E.G. Zurflueh (301)415-6002 DRAFT REGULATORY GUIDE DG-1101 (Proposed Revision 2 of Regulatory Guide 1.132)

SITE INVESTIGATIONS FOR FOUNDATIONS OF NUCLEAR POWER PLANTS A. INTRODUCTION This regulatory guide describes field investigations for determining the geological, engineering, and hydrological characteristics of a prospective plant site. It provides guidance for developing geologic information on stratigraphy, lithology, and geologic structure and history of the site. The investigations recommended provide data defining the static and dynamic engineering properties of soil and rock materials at the site and their spatial distribution. Thus, the site investigations provide a basis for evaluating the safety of the site with respect to the performance of foundations and earthworks under anticipated loading conditions, including earthquakes.

In 1996, the Nuclear Regulatory Commission (NRC) issued new regulations concerning site evaluation factors and geologic and seismic siting criteria for nuclear power plants (10 CFR Part 100, "Reactor Site Criteria," in Subpart B, "Evaluation Factors for Stationary Power Reactor Site Applications on or After January 10, 1997"). In particular, § § 100.20(c), 100.21 (d), and 100.23 of Part 100 establish requirements for conducting site investigations for nuclear power plants for site applications submitted after January 10, 1997.

Safety-related site characteristics are identified in detail in Regulatory Guide 1.70, "Standard Format and Content of Safety Analysis Reports for Nuclear Power Plants." Regulatory Guide 4.7, "General Site Suitability Criteria for Nuclear Power Stations," discusses major site characteristics that affect site suitability.

This regulatory guide describes methods acceptable to the NRC staff for conducting field investigations to acquire the data on geological and engineering characteristics of a site needed for a This regulatory guide is being issued in draft form to involve the public in the early stages of the development of a regulatory position in this area.

It has not received complete staff review or approval and does not represent an official NRC staff position.

Public comments are being solicited on this draft guide (including any implementation schedule) and its associated regulatory analysis or value/impact statement. Comments should be accompanied by appropriate supporting data. Written comments may be submitted to the Rules and Directives Branch, Office of Administration, U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001. Comments may be submitted electronically or downloaded through the NRC's interactive web site at <WWW.NRC.GOV> through Rulemaking. Copies of comments received may be examined at the NRC Public Document Room, 11555 Rockville Pike, Rockville, MD. Comments will be most helpful if received by May 10, 2001.

Requests for single copies of draft or active regulatory guides (which may be reproduced) or for placement on an automatic distribution list for single copies of future draft guides in specific divisions should be made to the U.S. Nuclear Regulatory Commission, Washington, DC 20555, Attention: Reproduction and Distribution Services Section, or by fax to (301)415-2289; or by email to DISTRIBUTION@NRC.GOV. Electronic copies of this draft guide are available through NRC's interactive web site (see above), on the NRC's web site< www.nrc.gov > in the Reference Library under Regulatory Guides, and in NRC's Public Electronic Reading Room at the same web site, under Accession Number

nuclear power plant site application. The guide includes recommendations for developing site-specific investigation programs and guidance for conducting subsurface investigations.

The guide is being revised to incorporate newer practices and insights. A report written by the U.S. Army Corps of Engineers staff, NUREG/CR-5738, was used as a technical basis for this guide and may be consulted for details of procedures. The appendices to this guide are taken from that publication.

Laboratory tests and analyses for determining soil and rock properties are described in Regulatory Guide 1.138, "Laboratory Investigations of Soils for Engineering Analysis and Design of Nuclear Power Plants." Regulatory Guide 1.165, "Identification and Characterization of Seismic Sources and Determination of Safe Shutdown Earthquake Ground Motion," defines investigations related to seismicity, faults, and vibratory ground motion. This guide does not deal with volcanologic or hydrologic investigations, except for groundwater measurements at the site. Considerations for flooding are described in Regulatory Guide 1.59, "Design Basis Floods for Nuclear Power Plants."

Regulatory guides are issued to describe to the public methods acceptable to the NRC staff for implementing specific parts of the NRC's regulations, to explain techniques used by the staff in evaluating specific problems or postulated accidents, and to provide guidance to applicants. Regulatory guides are not substitutes for regulations, and compliance with regulatory guides is not required. Regulatory guides are issued in draft form for public comment to involve the public in developing the regulatory positions. Draft regulatory guides have not received complete staff review; they therefore do not represent official NRC staff positions.

The information collections contained in this regulatory guide are covered by the requirements of 10 CFR Part 50, which were approved by the Office of Management and Budget, approval number 3150-0011. If a means used to impose an information collection does not display a currently valid OMB control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.

B. DISCUSSION PURPOSE The purpose of the site investigations described in this guide is to acquire the geotechnical data needed to design nuclear power plant foundations for safety and performance. They should define the overall site geology to the degree necessary to understand subsurface conditions and to identify potential geologic hazards that may exist at the site. Local groundwater conditions must also be defined. Investigations for hazards such as fault offsets, landslides, cavernous rocks, ground subsidence, and soil liquefaction are especially important.

Investigations described here are closely related to those contained in Regulatory Guide 1.165. The main purpose of that guide is to define seismologic and related geologic aspects of the site for determining the safe shutdown earthquake ground motion (SSE), and it includes investigations over a broader area. This guide is more narrowly focused on the 2

geologic and engineering characteristics of the specific site. Appendix D to Regulatory Guide 1.165 gives detailed instructions for investigating tectonic and nontectonic surface deformation. As these types of deformation are also part of the site engineering data, applicants are referred to that Appendix for appropriate guidance.

The aim of site investigations is to gain an understanding of the three-dimensional distribution of geological features (rocks, soils, extent of weathering, fractures, etc.) at the site, and to obtain the soil and rock properties that are needed for designing foundations for a nuclear power plant and associated critical structures. The density of data gathered varies over a plant site according to the variability of the soils and rocks and the importance assigned to structures planned for a particular location. Display and visualization of such data has traditionally been accomplished with maps and cross-sections. Given the computer resources and Geographic Information Systems (GIS) available today, it is advantageous to incorporate the data into a GIS database, which then permits plotting of appropriate maps, cross sections, and three-dimensional displays. Employing a GIS also permits using different scales for effective viewing.

It is worthwhile to point out that good site investigations have the added benefit of saving time and money by reducing problems in licensing and construction. A case study report on geotechnical investigations, for example, concludes that additional geotechnical information would almost always save time and costs (National Research Council).

C. REGULATORY POSITION

1. GENERAL A well-thought-out program of site exploration, progressing from literature search and reconnaissance investigations to detailed site investigation, construction mapping, and final as-built data compilation should be established to form a clear basis for the geotechnical work and foundation design. Because details of an actual site investigation program will be site dependent, such a program should be tailored to the specific conditions of the site using sound professional judgment. The program should be flexible and adjusted as the site investigation proceeds, with the advice of personnel experienced in site investigations. Also, this guide represents techniques available at the date of issuance. As the science advances, useful procedures and equipment should be included as they are developed and accepted by the profession.

Site investigations for nuclear power plants should be adequate, in terms of thoroughness, suitability of the methods used, quality of execution of the work, and documentation, to permit an accurate determination of the geologic and geotechnical conditions that affect the design, performance, and safety of the plant. The investigations should provide information needed to assess foundation conditions at the site and to perform engineering analysis and design with reasonable assurance that foundation conditions have been realistically estimated.

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2. TYPES OF DATA TO BE ACQUIRED 2.1 Geological Conditions Geological conditions comprise general geological conditions, the types and structure of soils and rocks at the surface and in the subsurface, the degree and extent of weathering, and petrological characteristics, such as structure, texture, and composition.

The presence of potential hazards, such as faulting, landslides, erosion, or deposition by rivers or on shorelines; caverns formed by dissolution or mining activity; ground subsidence; and soil shrinking and swelling, is also to be determined. Data to evaluate the soil liquefaction potential and the orientation and characteristics of bedding, foliations, or jointing and faulting are also needed.

2.2 Engineering Properties of Soils and Rocks These properties include density and seismic velocities and parameters of strength, elasticity, and plasticity. Some of these properties can be measured in situ, and those measurements together with sample collection are discussed in this guide. Detailed determination of these and other engineering properties also requires laboratory testing, which is described in Regulatory Guide 1.138.

2.3 Groundwater Conditions Only conditions at the site, such as groundwater levels, thickness of aquifers and confining beds, groundwater flow patterns, and transmissivities and storage coefficients are to be determined.

2.4 Man-Induced Conditions The existing infrastructure is to be located, together with dams or reservoirs whose locations may cause a flooding hazard or produce loading effects at the site. Past or ongoing activities, such as mining or oil and gas production, and other fluid extraction or injection also need to be documented. The presence of former industrial sites, underground storage tanks, or landfills should be determined and the potential for hazardous, toxic, or radioactive waste investigated.

2.5 Cultural and Environmental Considerations Cultural resources, such as archaeological sites and artifacts, must be considered to comply with the Archaeological Resources Protection Act of 1979 and the Native American Graves Protection and Repatriation Act of 1990.

Aspects of the Clean Water Act (33 U.S.C. 1344) must also be taken into account.

Placement of fill into wetlands is regulated at the national level. State and local wetland protection laws may also apply. Guidance on identifying and delineating wetlands is given in the Corps of Engineers Wetlands Delineation Manual (1987). Information on applications for Section 404 permits for modifying wetlands can be obtained from District Offices of the Corps.

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2.6 Related Considerations Guidance on seismicity and related seismic data and historical records is in Regulatory Guide 1.165, together with guidance on vibratory ground motion resulting from earthquakes. Although this subject is not repeated here, many of the investigations listed in that guide could and should be coordinated with the site investigations described here and conducted at the same time for greater efficiency. Appendix D to Regulatory Guide 1.165 is to be used as guidance for investigating tectonic and nontectonic surface deformation.

3. LITERATURE SEARCH AND RECONNAISSANCE 3.1 General Establishing the geological conditions and engineering properties of a site is an iterative process whereby successive phases of investigation lead to increasingly detailed data. Therefore, it is important to have a proper system for recording the data and gaining a three-dimensional understanding of site conditions. At the present time, a GIS is the most efficient way to record and present the data. A well-thought-out system of classifying and filing information is also important and is part of the quality assurance required for the project (see Regulatory Position 7.2). Appendix A to this guide lists some of the geologic features and conditions that may have to be considered in site investigations.

3.2 Existing Literature and Map Studies The first step in the site investigation is to acquire existing knowledge of geological and other site conditions. An understanding of the regional geology must also be developed in order to interpret the rocks and soils of the site in their proper context.

Published material and existing maps of topography, geology, hydrology, soils, etc., can reveal a wealth of information on site conditions. Study of aerial photographs and other remote-sensing imagery complements this information.

Possible sources of current and historical documentary information may include:

0 Geology and engineering departments of State and local universities,

• County governments, many of which have GIS data of various kinds available, 0 State government agencies such as the State Geological Survey,

• U.S. government agencies such as the U.S. Geological Survey, the Bureau of Reclamation, and the U.S. Army Corps of Engineers,

• Newspaper records of earthquakes, floods, landslides, and other events of significance,

• Interviews with local inhabitants and professionals.

Published maps such as topographic, geologic, and soils maps can be used to obtain information on the site, to aid in the field reconnaissance, and as a basis for further work.

Aerial photographs and other remote-sensing imagery are also useful and complement this 5

information. For additional sources, see Appendix B to this guide that contains a list of potential sources for maps, imagery, and other geologic data.

Some of the basic aspects that should be investigated include geologic conditions, previous land uses, and existing construction and infrastructure. Plans held by utilities should be consulted to locate services such as water, gas, electric, and communication lines. The locations of power lines, pipelines, and access routes should also be established.

Mining records should be consulted for locations of abandoned adits, shafts, benches, and tailings embankments. Oil, gas, and water well records as well as oil exploration data can provide valuable subsurface information. Cultural resources such as historical and archaeological sites should be identified.

3.3 Field Reconnaissance In addition to the study of published data, it is essential to perform a preliminary field reconnaissance of the site and its surrounding area. This will give a more realistic assessment of site conditions and regional geology and provide a basis for a detailed site investigation plan. Appendix A shows a list of special geologic features and conditions to be considered. In addition to the specific site, potential borrow areas, quarry sites, or water impoundment areas need to be investigated.

The team performing the reconnaissance should include, as a minimum, a geologist and a civil engineer, and may include other specialists such as an engineering geologist or geophysicist. An appropriate topographic or geologic map should be used during the field reconnaissance to note findings of interest. A Global Positioning System (GPS) unit may be advantageous for recording locations in the field, as noted more in detail in Regulatory Position 7.1.

3.4 Site Suitability After the reconnaissance investigations, sufficient information will be available to make a preliminary determination of site suitability and to formulate a plan for detailed site investigations. The presence of features that can cause permanent ground displacement such as fault displacement and settlement or subsidence, swelling soils and shales, or other hazards including underground cavities, landslides, or periodic flooding, may make proper engineering design difficult and usually will require extensive additional investigations. In such cases, it may be advantageous to abandon the site.

4. DETAILED SITE INVESTIGATIONS 4.1 General Whereas the reconnaissance phase is oriented toward establishing the viability of the site, this phase is the task of acquiring all the geologic factors and engineering properties needed for design and construction of a plant, including its critical structures. The investigation should, therefore, be carried out in much greater detail, and a multidisciplinary team is needed to accomplish the varied tasks of this investigation.

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Engineering properties of rocks and soils are determined through in situ testing, field geophysical measurements, and laboratory testing. This guide describes in situ testing and the field geophysical measurements, as well as drilling and sampling procedures used to gather samples for laboratory testing. For laboratory testing procedures, refer to Regulatory Guide 1.138.

Data sufficient to clearly justify all conclusions should be presented. Site information to be developed should include, as appropriate, (1) topographic, hydrologic, hydrographic, and geologic maps, (2) plot plans, showing locations of major structures and exploration, (3) boring logs and logs of exploratory trenches and excavations, (4) geologic profiles showing excavation limits for structures, and (5) geophysical data, such as seismic survey time-distance plots, resistivity curves, seismic reflection cross-sections, maps, profiles, borehole logs, and surveys. Using techniques of investigation and sampling other than those indicated in this guide is acceptable when it can be shown that the alternative methods yield satisfactory results.

Locations of all boreholes, piezometers, observation wells, trenches, exploration pits, and geophysical measurements should be surveyed in both plan and elevation. This three dimensional information should be entered into a GIS database, and suitable cross-sections, maps, and plans should be prepared to facilitate visualization of the geological information.

Further details are given in Regulatory Position 7.1.

4.2 Surface Investigations Detailed surface geological and geotechnical engineering investigations should be conducted over the site area to assess all the pertinent soil and rock characteristics. Some of the special geological features and conditions to be considered are listed in Appendix A.

The first steps in detailed site investigations are to prepare topographic maps at suitable scales to (1) plot geologic, structural, and engineering details at the site and (2) note conditions in the surrounding areas that are related, for instance, to borrow areas, quarries, or access roads. Aerial photographs and stereo pairs, together with other remote sensing imagery, may be of value for regional analysis, determination of fault and fracture patterns, and other features of interest.

Detailed mapping of topographic, hydrologic, and surface geologic features should be conducted, as appropriate for the particular site conditions, with scales and contour intervals suitable for site evaluation and engineering design (see also Regulatory Position 7.1 ). For sites located offshore or near coasts, lakes or rivers, this may include detailed hydrographic surveys. Rock outcrops, soil conditions, evidence of past landslides or soil liquefaction, faults, fracture traces, geologic contacts, and lineaments should be identified and mapped. Details of local engineering geology and soil conditions should also be mapped and recorded, together with surface-water features such as rivers, streams, or lakes, as well as local surface drainage channels, ponds, springs, and sinks.

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4.3 Subsurface Investigations Subsurface explorations serve to expand the knowledge of the three-dimensional distribution of both geologic conditions (soils, rocks, structure) and engineering properties at the site and at borrow areas, as well as to gain further information on possible safety hazards such as underground cavities, hidden faults or contacts. The investigations should be carried out using a variety of appropriate methods, including borings and excavations augmented by geophysical measurements. Methods of conducting subsurface investigations are tabulated in Appendix C to this guide.

The locations and depths of borings and measurements should be chosen such that the site geology and foundation conditions are sufficiently defined in lateral extent and depth to permit designing all needed structures and excavations. The information acquired should also be such that engineering geologic cross-sections can be constructed through foundations of safety-related structures and other important locations.

Subsurface explorations for less critical foundations of power plants should be carried out with spacing and depth of penetration as necessary to define the general geologic and foundation conditions of the site. Subsurface investigations in areas remote from plant foundations may be needed to complete the geologic description of the site and to confirm geologic and foundation conditions.

Boreholes are one of the most effective means of obtaining detailed information on geologic formations in the subsurface and their engineering properties. Cores and samples recovered, geophysical and other borehole surveys, and in situ tests all contribute to the range of information to be derived from boreholes. Excavations in the form of test pits, trenches, and exploratory shafts may be used to complement the borehole exploration; they permit acquiring more detailed and visual information on rock and soil conditions and conducting detailed fault studies, in situ density tests, and high-quality sampling.

4.3.1 Borings and Exploratory Excavations Field operations should be supervised by experienced professional personnel at the site of operations, and systematic standards of practice should be followed. Procedures and equipment used to carry out the field operations, including necessary calibrations, should be documented, as should all conditions encountered in various phases of the investigation. Personnel that are experienced and thoroughly familiar with sampling and testing procedures should inspect and document sampling results and transfer samples from the field to storage or laboratory facilities.

The complexity of geologic conditions and foundation requirements should be considered in choosing the actual distribution, number, and depth of borings and other excavations for a site. The investigative effort should be greatest at the locations of safety-related structures and may vary in density and scope in other areas according to their spatial and geological relations to the site. At least one continuously sampled boring should be used for each safety-related structure, and the boring should extend at least 10 m (33 ft) below the lowest part of planned foundations.

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NUREG/CR-5738 describes procedures for borings and exploratory excavations. A table from that report that shows widely used techniques for subsurface investigations and describes the applicability and limitations of these methods is reproduced in Appendix C.

General guidelines for spacing and depth of borings are found in Appendix D.

4.3.1.1 Spacing. The spacing and depth of borings for safety-related structures should be chosen according to the foundation requirements and the complexity of anticipated subsurface conditions. Appendix D gives general guidelines concerning this subject. Uniform conditions permit the maximum spacing of borings in a regular grid for adequate definition of subsurface conditions. Subsurface conditions may be considered favorable or uniform if the geologic and stratigraphic features to be defined can be correlated from one boring location to the next with relatively smooth variations in thicknesses or properties of the geologic units. An occasional anomaly or a limited number of unexpected lateral variations may occur.

If site conditions are non-uniform, a regular grid may not provide the most effective borehole distribution. Soil or rock deposits may be encountered in which the deposition patterns are so complex that only the major stratigraphic boundaries are correlatable, and material types or properties may vary within major geologic units in an apparently random manner from one boring to another. The number and distribution of borings needed for these conditions are determined by the degree of resolution needed to define foundation properties. The goal is to define the thicknesses of the various material types, their degree of variability, and their range of material properties.

If there is evidence suggesting the presence of local adverse anomalies or discontinuities such as cavities, sinkholes, fissures, faults, brecciation, and lenses or pockets of unsuitable material, supplementary borings at a spacing small enough to detect and delineate these features are needed. It is important that these borings penetrate all suspect zones or extend to depths below which their presence would not influence the safety of the structures. Geophysical investigations should be used to supplement the boring program.

4.3.1.2 Drilling Procedures. Drilling methods and procedures should be compatible with sampling requirements and the methods of sample recovery. Many of the methods are discussed in detail in EM 1110-0-1906 and Das. The top of the hole should be protected by a suitable surface casing where needed. Below ground surface, the borehole should be protected by drilling mud or casing, as necessary, to prevent caving and disturbance of materials to be sampled. The use of drilling mud is preferred to prevent disturbance when obtaining undisturbed samples of coarse-grained soils. However, casing may be used if proper steps are taken to prevent disturbance of the soil being sampled and to prevent upward movement of soil into the casing. After use, each borehole should be grouted in accordance with State and local codes to prevent vertical movement of groundwater through the borehole.

Borehole elevation and depths into the borehole should be measured to the nearest 3 cm (0.1 ft) and should be correlatable to the elevation datum used for the site. Surveys of vertical deviation should be run in all boreholes that are used for crosshole seismic tests and other tests where deviation affects the use of data obtained. Boreholes with depths 9

greater than about 30 m (100 ft) should also be surveyed for deviation. Details of information that should be presented on logs of subsurface investigations are given in Regulatory Position 4.5.

4.3.2 Sampling Sampling of soils in boreholes should include, as a minimum, the recovery of samples at regular intervals and at changes in materials. Alternating split spoon and undisturbed samples with depth is recommended. Color photographs of all cores should be taken soon after removal from the borehole to document the condition of the soils at the time of drilling.

4.3.2.1 Sampling Rock. The engineering characteristics of rocks are related primarily to their composition, structure, bedding, jointing, fracturing, and weathering. Core samples are needed to observe and define these features. Suitable coring methods should be employed, and rocks should be sampled to a depth below which rock characteristics do not influence foundation performance. Deeper borings may be needed to investigate zones critical to the evaluation of the site geology. Within the depth intervals influencing foundation performance, zones of poor core recovery or low rock quality designation (RQD),

zones requiring casing, and other zones where drilling difficulties are encountered should be investigated. The nature, geometry, and spacing of any discontinuities or anomalous zones should be determined by means of suitable logging or in situ observation methods. Areas with evidence of significant residual stresses should be evaluated on the basis of in situ stress or strain measurements. If it is necessary to determine dip and strike of bedding planes or discontinuities, oriented cores may be needed.

4.3.2.2 Sampling Coarse-Grained Soils. For coarse-grained soils, samples should be taken at depth intervals no greater than 1.5 m (5 ft), Beyond a depth of 15 m (50 ft) below foundation level, the depth interval for sampling may be increased to 3 m (10 ft).

Also, one or more borings for each major structure should be continuously sampled.

Requirements for undisturbed sampling of coarse-grained soils will depend on actual site conditions and planned laboratory testing. Some general guidelines for recovering undisturbed samples are given in Regulatory Position 4.3.2.4 of this guide. Experimentation with different sampling techniques may be necessary to determine the method best suited to local soil conditions.

Split spoon sampling and standard penetration tests should be used with sufficient coverage to define the soil profile and variations of soil conditions. Cone penetration tests may also be made to provide useful supplemental data if the cone test data are properly calibrated to site conditions.

Suitable samples should be obtained for soil identification and classification, mechanical analyses, and anticipated laboratory testing. For cyclic loading tests, it is important to obtain good quality undisturbed samples for testing. The need for, number, and distribution of samples will depend on testing requirements and the variability of the soil conditions. In general, however, samples should be included from at least one principal boring at the location of each safety-related structure. Samples should be obtained at regular intervals in depth and when changes in materials occur. Criteria for sampling are given in Regulatory Position 4.3.2.

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Coarse-grained soils containing gravels and boulders are among the most difficult materials to sample. Obtaining good quality samples often requires the use of trenches, pits, or other accessible excavations into the zones of interest. Standard penetration test results from these materials may be misleading and must be interpreted very carefully.

When sampling of coarse soils is difficult, information that may be lost when the soil is later classified in the laboratory should be recorded in the field. This information should include observed estimates of the percentage of cobbles, boulders, and coarse material and the hardness, shape, surface coating, and degree of weathering of coarse materials.

4.3.2.3 Sampling Moderately Compressible or Normally Consolidated Clay or Clayey Soils. The properties of a fine-grained soil are related to the in situ structure of the soil, and undisturbed samples should be obtained. Procedures for obtaining undisturbed samples are discussed in Regulatory Position 4.3.2.4 of this guide.

For compressible or normally consolidated clays, undisturbed samples should be continuous throughout the compressible strata in one or more principal borings for each major structure. These samples should be obtained by means of suitable fixed piston, thin wall tube samplers (see EM 1110-1-1906 for detailed procedures) or by methods that yield samples of equivalent quality. Borings used for undisturbed sampling of soils should be at least 7.5 cm (3 inches) in diameter.

4.3.2.4 Obtaining Undisturbed Samples. In a strict sense, it is physically impossible to obtain "undisturbed" samples in borings because of the adverse effects resulting from the sampling process itself (e.g., unloading caused by removal from confinement) and from shipping or handling. Undisturbed samples are normally obtained using one of two general methods: push samplers or rotary samplers. These methods permit obtaining satisfactory samples for shear strength, consolidation, permeability, and density tests, provided careful measurements are made to document volume changes that occur during each step in the sampling process. Undisturbed samples can be sliced to permit detailed study of subsoil stratification, joints, fissures, failure planes, and other details.

Push sampling involves pushing a thin-walled tube, using the hydraulic system of the drill rig, then enlarging the diameter of the sampled interval by some "clean out" method before beginning to sample again. Commonly used systems for push samples include the Hvorslev fixed-position sampler and the Osterberg hydraulic piston sampler. Rotary samplers are considered slightly more disruptive to soil structure and involve a double tube arrangement similar to a rock coring operation, except that the inner barrel shoe is adjustable and generally extends beyond the front of the rotating outer bit. This reduces the disturbance caused to the sample from the drill fluid and bit rotation. Commonly used rotational samplers include the Denison barrel and the Pitcher Sampler.

Undisturbed samples of clays and silts can be obtained, as well as nearly undisturbed samples of some sands. Care is necessary in transporting any undisturbed sample; sands and silts are particularly vulnerable to vibration disturbance. One method to prevent handling disturbance is to obtain 7.5 cm (3 in.) Shelby tube samples, drain them, and freeze them before transportation. There are no standard or generally accepted methods for undisturbed sampling of cohesionless soils. Such soils can be recovered by 11

in-situ freezing, followed by sampling with a rotary core barrel. For any freezing method, disturbance by cryogenic effects must be taken into account.

Chemical stabilization or impregnation can also be used as an option to sample and preserve the natural structure of cohesionless granular material. Agar has been used with positive results as an impregnation material for undisturbed sampling of sands below the water table as an alternative to freezing. Chemical impregnation can be used either in situ before sampling or after sampling to avoid further disturbance in transporting and handling the samples. This alternative to freezing is less expensive and produces samples that are easier to manage after collection. Removal of the impregnating material may be accomplished once the sample is in the laboratory.

Test pits, trenches, and shafts offer the only effective access to collect high quality block samples and to obtain detailed information on stratification, discontinuities, or preexisting shear surfaces in the ground. Cost increases with depth as the need for side wall support arises. Samples can be obtained by means of hand-carving oversized blocks of soil or hand-advancing of thin-walled tubes.

4.3.2.5 Borrow Materials. Exploration of borrow sources serves to determine the location and amount of available borrow materials. Borrow area investigations should use horizontal and vertical intervals sufficient to determine material variability and should include adequate sampling of representative materials for laboratory testing.

4.3.2.6 Materials Unsuitable for Foundations. Boundaries of unsuitable materials should be delineated by means of borings and representative sampling and testing. These boundaries should be used to define the required excavation limits.

4.3.3 Transportation and Storage of Samples The handling, storage, and transportation of samples is as critical for sample quality as the collection procedures. Disturbance of samples after collection can happen in a variety of ways and transform samples from high quality, to slightly disturbed, to completely worthless. Soil samples can change dramatically because of moisture loss, moisture migration within the sample, freezing, vibration, shock, or chemical reactions.

Moisture loss may not be critical on representative samples, but it is preferable that it be kept to a minimum. Moisture migration within a sample causes differential residual pore pressures to equalize with time. Water can move from one formation to another, causing significant changes in the undrained strength and compressibility of the sample.

Freezing of clay or silt samples can cause ice lenses to form and severely disturb the 0

samples. Storage room temperatures for these kinds of samples should be kept above 4 C.

Vibration or shock can provoke remolding and strength or density changes, especially in soft and sensitive clays or cohesionless samples. Transportation arrangements to avoid these effects need to be carefully designed. Chemical reactions between samples and their containers can occur during storage and can induce changes that affect soil plasticity, compressibility, or shear strength. Therefore, the correct selection of sample container material is important.

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Cohesionless soil samples (unless stabilized chemically or by freezing) are particularly sensitive to disturbance from impact and vibration during removal from the borehole or sampler and subsequent handling. Samples should be kept at all times in the same orientation as that in which they were sampled (e.g., vertical position if sampled in a vertical borehole), well padded for isolation from vibration and impact, and transported with extreme care if undisturbed samples are required.

4.3.4 In Situ.Testing In situ testing of soil and rock materials should be conducted where necessary for definition of foundation properties, using boreholes, excavations, test pits, and trenches that are either available or have been prepared for the purpose of sampling and testing.

Larger block samples for laboratory testing can also be obtained in such locations. Some of the applicable in situ testing methods are shown in Appendix F. For further description of procedures see NUREG/CR-5738.

In situ tests are often the best means to determine the engineering properties of subsurface materials and, in some cases, may be the only way to obtain meaningful results.

Some materials are hard to sample and transport, while keeping them representative of field conditions, because of softness, lack of cohesion, or composition. In situ techniques offer an option for evaluating soils and rocks that cannot be sampled for laboratory analysis.

Interpretation of in situ test results in soils, clay shales, and moisture-sensitive rocks requires consideration of the drainage that may occur during the test. Consolidation during soil testing makes it difficult to determine whether the results relate to unconsolidated undrained, consolidated-undrained, consolidated-drained conditions, or to intermediate conditions between these limiting states. Interpretation of in situ test results requires complete evaluation of the test conditions and limitations.

Rock formations are generally separated by natural joints and/or bedding planes, resulting in a system of irregularly shaped blocks that respond as a discontinuum to various loading conditions. Individual blocks have relatively high strengths, whereas the strength along discontinuities is reduced and highly anisotropic. Commonly, little or no tensile strength exists across discontinuities. Large-scale in situ tests tend to average out the effect of complex interactions. In situ tests in rock are used to determine in situ stresses and deformation properties, including the shear strength of the jointed rock mass. They also help to measure strength and residual stresses along discontinuities or weak seams in the rock mass. In situ testing performed in weak, near-surface rocks include penetration tests, plate loading tests, pressure-meter tests, and field geophysical techniques.

Table F-2 in Appendix F lists in situ tests that are useful for determining the shear strength of subsurface materials. Direct shear strength tests in rock measure peak and residual direct shear strength as a function of normal stress on the shear plane. Direct shear strength from intact rock can be measured in the laboratory if the specimen can be cut and transported without disturbance. In situ shear tests are discussed and compared in Nicholson and in Bowles. The suggested in situ method for determining direct shear strength of rocks is described in RTH 321-80.

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4.4 Geophysical Investigations 4.4.1 General Geophysical methods include surface geophysics, borehole logging, and cross borehole measurements. In all cases, these methods are a means of exploring the subsurface. Geophysical measurements should be used to fill in information between surface outcrops, trenches, and boreholes. Such measurements permit acquiring more continuous, and sometimes deeper, subsurface coverage, including data on geological and hydrological conditions and certain engineering properties of materials. They are of particular value in tying together information from various sources.

Available geophysical and borehole logging methods are listed in Appendix E to this guide and in EM- 1110-1-1802. For boreholes that are deeper than 30 m (100 ft) or are used for crosshole measurements, borehole deviation should be measured. Geophysical measurements, borehole logging, and interpretation of geophysical measurements should be carried out by personnel that have the necessary background and experience in these techniques. Parameters of acquisition (spacings, instrument settings, etc.) and processing should be recorded to allow for proper interpretation of results.

At soil sites or rock sites with substantial weathering, crosshole shear wave measurements should be conducted in boreholes deep enough to allow determining the site amplification for seismic waves. These boreholes should also be sampled and logged as appropriate, including acoustic logging. Other geophysical measurements, such as seismic refraction and reflection and microseismic monitoring, may also be used for site amplification calculations.

4.4.2 Surface Geophysics Recommended surface geophysical methods include seismic refraction and reflection surveys, as well as surface electromagnetic or electrical resistivity surveys. Other methods such as gravity, magnetics, and ground penetrating radar may also be used as appropriate.

Spectral analysis of surface waves may be used to measure shear-wave velocity profiles.

The method permits deriving elastic moduli and soil layer thicknesses (Gucunski and Woods, Stokoe and Nazarian, Stokoe et al.). The surface geophysical measurements should be correlated with borehole geophysical and geological logs to derive maximum benefit from the measurements.

4.4.3 Borehole Geophysics Boreholes should be logged with a suitable suite of geophysical logging methods.

Borehole logs are useful for determining lithological, hydrological, and engineering properties of subsurface horizons. They are also very useful for the correlation of stratigraphic horizons between boreholes. Some of the applicable methods are shown in Appendix E to this guide, together with the engineering parameters they help to determine.

Crosshole geophysical measurements may be used to obtain detailed information on the region between two boreholes and to derive engineering and hydrologic properties, such as shear modulus, porosity, and permeability. Measurements of shear- and compressional wave velocities are most common, but electrical resistivity and electromagnetic methods may also be employed. When very detailed information is desired, tomographic methods 14

may be used that can provide a detailed picture of geophysical properties between boreholes.

Acoustic borehole logging and crosshole shear-wave measurements generally are low strain measurements. In rock, they provide a suitable approximation of shear modulus even under higher strain conditions. In soil, on the other hand, the modulus depends strongly on the strain level. However, so-called high strain shear-wave methods (crosshole) in soil are usually ineffective, because nonlinear effects may occur. Other in situ and laboratory tests are more promising for such measurements.

4.5 Logs of Subsurface Investigations Boring logs should contain the date when the boring was made, the location of the boring, the depths of borings, and the elevations with respect to a permanent benchmark.

The logs should also include the elevations of the top and bottom of borings and the elevations of the boundaries of soil or rock strata, as well as the level at which the water table was encountered. In addition, the classification and description of soil and rock layers, blow count values obtained from Standard Penetration Tests, percent recovery of rock core, quantity of core not recovered for each core interval or drill run, and Rock Quality Designation (RQD) should be noted.

Results of field permeability tests and geophysical borehole logging should also be included on logs. The type of tools used in making the boring should be recorded. If the tools were changed, the depth at which the change was made and the reason for the change should be noted. Notes should be provided of everything significant to the interpretation of subsurface conditions, such as incidents of settling or dropping of drill rods, abnormally low resistance to drilling or advance of samplers, core losses, or instability or heave of the side and bottom of boreholes. Influx of groundwater, depths and amounts of water or drilling mud losses, together with depths at which circulation is recovered, and any other special feature or occurrence should be recorded on boring logs and geological cross sections.

Incomplete or abandoned borings should be described with the same care as successfully completed borings. Logs of exploratory trenches and other excavations should be presented in a graphic format in which important components of the soil matrix and structural features in rock are shown in sufficient detail to permit independent evaluation.

The location of all explorations should be recorded in the GIS and shown on geologic cross sections, together with elevations and important data.

5. GROUNDWATER INVESTIGATIONS Knowledge of groundwater conditions, their relationship to surface waters, and variations associated with seasons or tides is needed for foundation analyses. Groundwater conditions are normally observed in borings at the time they are made. However, such data should be supplemented by groundwater observations in properly installed wells or piezometers that are read at regular intervals from the time of their installation at least through the construction period. Appendix G to this guide lists types of instruments for 15

measuring groundwater pressure and their advantages and limitations. ASTM D 5092-95 provides guidance on the design and installation of groundwater monitoring wells. Types of piezometers, construction details, and sounding devices are described in EM 1110-2-1908.

Groundwater conditions should be observed during the course of the site investigation, and measurements should be made of the water level in exploratory borings.

The groundwater or drilling mud level should be measured at the start of each workday for borings in progress, at the completion of drilling, and when the water levels in the borings have stabilized. In addition to the normal borehole groundwater measurements, piezometers or wells should be installed in as many locations as needed to adequately define the groundwater environment. Pumping tests are a preferred method for evaluating local permeability characteristics and assessing dewatering requirements for construction and operation of the plant. For major excavations where construction dewatering is required, piezometers or observation wells should be used during construction to monitor the groundwater surface and pore pressures beneath the excavation and in the adjacent ground. This guide does not cover groundwater monitoring during construction of plants that are designed with permanent dewatering systems.

When the possibility of perched groundwater tables or artesian pressures is indicated by borings or other evidence, piezometers should be installed such that each piezometric level can be measured independently. Care should be taken in the design and installation of piezometers to prevent hydraulic communication between aquifers. The occurrence of artesian pressure in borings should be noted on boring logs, and the artesian heads should be measured and logged.

6. CONSTRUCTION MAPPING It is essential to verify during construction that in situ conditions have been realistically estimated during analysis and design. Excavations made during construction provide opportunities for obtaining additional geologic and geotechnical data. All construction excavations for safety-related structures and other excavations important to the verification of subsurface conditions should be geologically mapped and logged in detail.

This work is usually performed after the excavation has been cleaned to grade and just before the placement of concrete or backfill, to permit recording of geologic details in the foundation. Particular attention should be given to the identification of features that may be important to foundation behavior but were undetected in the investigation program.

Changes in foundation design should be noted on the appropriate plans, and newly discovered geologic features should be surveyed and entered into maps, cross-sections, and the database.

Features requiring excavation, such as structure foundations, cut slopes, tunnels, chambers, water inlets and outlets, should be mapped and investigated for geologic details that may be different from assumptions based on the pre-construction investigations. This work is usually performed after the excavation has been cleaned to grade and just before the placement of concrete or backfill. These maps should be prepared to show any feature installed to improve, modify, or control geologic conditions. Some examples are rock reinforcing systems, permanent dewatering systems, and special treatment areas. All 16

features found or installed should be surveyed and entered into maps, cross sections, and the database. Photographic or videographic records (or both) of foundation mapping and treatment should be made. Generally, the GiS and other databases should be continuously updated, up to and including the construction phase, resulting in as-built information.

Appendix A to NUREG/CR-5738 provides detailed guidance on technical procedures for mapping foundations. Mapping of tunnels and other underground openings must be planned differently from foundation mapping. Design requirements for support of openings may require installation of support before an adequate cleanup can be made for mapping purposes. Consequently, mapping should be performed as the heading or opening is advanced and during the installation of support features. This requires a well trained geologist, engineering geologist, or geological engineer at the excavation at all times.

Specifications should be included in construction plans for periodic cleaning of exposed surfaces and to allow a reasonable length of time for mapping. Technical procedures for mapping tunnels are outlined in Appendix B to NUREG/CR-5738 and can be modified for large chambers.

The person in charge of foundation mapping should be familiar with the design and should consult with design personnel during excavation work whenever differences between the actual geology and the design base geological model are found. The same person should be involved in all decisions concerning changes in foundation design or additional foundation treatment that may be necessary based on observed conditions.

The previous requirement for a two-step licensing procedure for nuclear power plants, involving first a construction permit (CP), and then an operating license (OL), has been modified to allow for an alternative procedure. Requirements for applying for a combined license for a nuclear power facility are contained in Subpart C of 10 CFR Part 52.

The combined licensing procedure may result in the award of a license before the start of construction. However, the need for construction mapping applies equally under the combined license procedure. In the past, previously unknown faults were often discovered in site excavations for nuclear power plants, demonstrating the importance of mapping such features while the excavations' walls and bases are exposed and the importance of assessing their potential to generate offsets or ground motion. Documents supporting the combined license application (Safety Analysis Reports) should, therefore, include plans to geologically map all excavations. Licensees and applicants must meet the requirements of 10 CFR 50.9 regarding notification to the NRC of information concerning a regulated activity with significant implications for public health and safety or common defense and security.

7. SUPPORT FUNCTIONS 7.1 Surveying/Mapping/GIS Surveying is an important function that should accompany all essential site investigation activities from reconnaissance through construction mapping. There are many methods of surveying available today, from traditional triangulation or plane table work together with leveling to electronic distance and GPS measurements. For mapping small 17

areas, plane table methods may still be among the fastest. In most cases, however, GPS or DGPS (differential GPS) together with automated recording and computing procedures is the most suitable method. Procedures for GPS surveying can be found in EM-1 110-1-1003.

The GPS measurements and other surveyed locations should be tied to National Geodetic Survey (NGS) markers in order to be compatible with topographic maps and digital maps of various kinds. The vertical component of GPS measurements is the least accurate component, but it is being improved with more accurate satellite orbits and other corrections. For greater accuracy, it may still be necessary to perform a certain amount of conventional leveling.

A suitable coordinate system for the site should be chosen. Three-dimensional coordinate systems include the World Geodetic System of 1984 (WGS 84), the International Terrestrial Reference Frame (ITRF), and the North American Datum of 1983 (NAD 83). Coordinates should be referred to NAD 83 to be legally recognized in most U.S.

jurisdictions. Moreover, NGS provides software for converting the ellipsoid-based heights of NAD 83 to the sea-level-based heights that appear on topographic maps. NAD 83 coordinates are readily determined when measurements tie the site to an NGS marker.

All three-dimensional information should be entered into a GIS database. One of the advantages of a GIS is that data of various kinds, in the form of tables, can be associated with a coordinate system and then recalled to form graphical output of a desired type. The choice of the particular system used is up to the applicant. However, the data should be in a format that is readily readable.

In order to record the information gathered during site investigations, to place geological, geotechnical, and sampling/testing information into a spatial context, and to permit visual display in maps and cross sections, it is necessary to have a staff available that is experienced in surveying and in storing and displaying data in a GIS throughout all phases of site investigation and construction. These are essential activities that should be given proper emphasis and support by applicants.

7.2 Database/Sample Repository/Quality Assurance All data acquired during the site investigation should be organized into suitable categories and preserved as a permanent record, at least until the power plant is licensed to operate and all matters relating to the interpretation of subsurface conditions at the site have been resolved. Much of the data will already be part of the GIS database but other data and records, such as logs of operations, photographs, test results, and engineering evaluations and calculations, should also be preserved for further reference.

Samples and rock cores from principal borings should also be retained. Regulatory Position 4.3.3 and Chapter 7 of NUREG/CR-5738 describe procedures for handling and storing samples. The need to retain samples and core beyond the recommended time is a matter of judgment and should be evaluated on a case-by-case basis. For example, soil samples in tubes will deteriorate with time and will not be suitable for undisturbed testing; however, they may be used as a visual record of what the foundation material is like.

Similarly, cores of rock subject to slaking and rapid weathering such as shale will also 18

deteriorate. It is recommended that photographs of soil samples and rock cores, together with field and final logs of all borings, be preserved for a permanent record.

The site investigations should be included in the overall Quality Assurance program for plant design and construction according to the guidance in Regulatory Guide 1.28 and the requirements of Appendix B to 10 CFR Part 50. Field operations and records preservation should, therefore, be conducted in accordance with quality assurance principles and procedures.

D. IMPLEMENTATION The purpose of this section is to provide guidance to applicants and licensees regarding the NRC staff's plans for using this regulatory guide.

This proposed revision has been released to encourage public participation in its development. Except in those cases in which an applicant or licensee proposes an acceptable alternative method for complying with the specified portions of the NRC's regulations, the method to be described in the active guide reflecting public comments will be used in the evaluation of applications for construction permits, operating licenses, early site permits, or combined licenses submitted after January 10, 1997. This guide will not be used in the evaluation of an application for an operating license submitted after January 10, 1997, if the construction permit was issued before that date.

19

REFERENCES ASTM D 5092-95, "Practices for Design and Installation of Groundwater Monitoring Wells in Aquifers," 1998 Annual Book of ASTM Standards, Section 4, Construction, Vol. 4.09, Soil and Rock (I): D 420 - D 4914, 1995.'

Bowles, J.E., FoundationsAnalysis and Design, 5 th Ed., McGraw-Hill, New York, 1996.

Environmental Laboratory, "Corps of Engineers Wetlands Delineation Manual," Technical Report Y-87-1, U.S. Army Engineer Waterways Experiment Station, Vicksburg, MS, 1987.

Das, B.M., Principlesof GeotechnicalEngineering, 3 rd Ed., PWS Publishing, Boston, MA, 1994.

EM 1110-1-1003, "NAVSTAR Global Positioning System Surveying," Department of the Army, Office of the Chief of Engineers, Washington, DC, 1 995.

EM 1110-1-1802, "Geophysical Methods for Engineering and Environmental Investigations," Department of the Army, Office of the Chief of Engineers, Washington, DC, 1995.

EM 1110-1-1906, "Soil Sampling," Department of the Army, Office of the Chief of Engineers, Washington, DC, 1996.

EM 1110-2-1908 (Part 1), "Instrumentation of Embankment Dams and Levees," U.S.

Department of the Army, Office of the Chief of Engineers, Washington, DC, 1995.

Gucunski, N., and R.D. Woods, "Instrumentation for SASW Testing," Recent Advances in Instrumentation, Data Acquisition, and Testing in Soil Dynamics Proceedings, Geotechnical Special Publication No. 29, pp. 1-16, American Society of Civil Engineers, New York, 1991.

National Research Council, "Geotechnical Site Investigations for Underground Projects,"

Vol. 1 & 2, National Academy Press, Washington, DC, 1984.

Nicholson, G.A., "In Situ and Laboratory Shear Devices for Rock: A Comparison," TR GL 85-3, U.S. Army Corps of Engineers, Waterways Experiment Station, Vicksburg, MS, 1983.

NUREG/CR-5738, N. Torres, J.P. Koester, J.L. Llopis, "Field Investigations for Foundations of Nuclear Power Facilities," USNRC, November 1999.

Regulatory Guide 1.28, "Quality Assurance Program Requirements (Design and Construction)," USNRC, Revision 3, August 1985.

1 ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, phone (610)832-9500.

20

Regulatory Guide 1.59, "Design Basis Floods for Nuclear Power Plants," USNRC, Revision 2, August 1977.

Regulatory Guide 1.70, "Standard Format and Content of Safety Analysis Reports for Nuclear Power Plants (LWR Edition)," USNRC, Revision 3, November 1978.

Regulatory Guide 1.138, "Laboratory Investigations of Soils for Engineering Analysis and Design of Nuclear Power Plants," USNRC, April 1978.

Regulatory Guide 1.165, "Identification and Characterization of Seismic Sources and Determination of Safe Shutdown Earthquake Ground Motion," USNRC, March 1997.

Regulatory Guide 4.7, "General Site Suitability Criteria for Nuclear Power Stations," USNRC, Revision 2, April 1998.

RTH 321-80, "Suggested Method for In Situ Determination of Direct Shear Strength (ISRM),

U.S. Army Corps of Engineers, Waterways Experiment Station, Vicksburg, MS, 1980.

Stokoe, K. H., II, and S. Nazarian, "Use of Rayleigh Waves in Liquefaction Studies,"

Proceedings,Measurement and Use of Shear Wave Velocity for Evaluating Dynamic Soil Properties, held at Denver, CO, American Society of Civil Engineers, New York, NY, pp. 1 17, 1985.

Stokoe, K.H., et al., "Liquefaction Potential of Sands from Shear Wave Velocity,"

Proceedings,Ninth World Conference on Earthquake Engineering, Tokyo-Kyoto, Japan, Vol.

III, pp. 213-218, Japan Association for Earthquake Disaster Prevention, Tokyo, Japan, 1988.

21

APPENDIX A Special Geologic Features and Conditions Considered in Office Studies and Field Observations (EM 1110-1-1804, Department of the Army, 1984)

Geologic Feature or Condition Influence on Project Office Studies Field Observations Questions to Answer Landslides Stability of natural and Presence or age in project area or at Estimate areal extent (length and Are landslides found off site excavated slopes construction sites should be width) and height of slope in geologic formations of determined same type that will be affected by project construction?

Compute shear strength at failure. Estimate ground slope before and after What are probable previous Do failure strengths decrease with slide (may correspond to residual and present groundwater age of slopes-- especially for clays angle of friction) levels?

and clay shales?

Check highway and railway cuts and Do trees slope in an unnatural deep excavations, quarries and steep direction?

slopes Faults and Of decisive importance in Determine existence of known faults Verify presence at site, if possible, Are lineaments or possible I'* faulting; past seismic evaluations; age of and fault history from available from surface evidence; check poten fault traces apparent from seismic activity most recent fault movement information tial fault traces located from aerial regional aerial imagery?

may determine seismic design imagery earthquake magnitude, may be indicative of high state of stress Examine existing boring logs for Make field check of structures, cellars, which could result in foundation evidence of faulting from offset of chimneys, roads, fences, pipelines, heave or overstress in strata known faults, caves, inclination of underground works trees, offset in fence lines Stress relief Valley walls may have cracking Review pertinent geologic literature Examine wells and piezometers in val cracking and parallel to valley. Valley floors and reports for the valley area. leys to determine if levels are lower valley rebounding may have horizontal cracking. Check existing piezometer data for than normal groundwater regime (indi In some clay shales stress relief abnormally low levels in valley sides cates valley rebound not complete) from valley erosion or glacial and foundation; compare with action may not be complete normal groundwater levels outside valley (Continued)

APPENDIX A, Cont'd.

Geologic Feature or Condition Influence on Project Office Studies Field Observations Questions to Answer Sinkholes; karst Major effect on location of Examine air photos for evidence of Locate depressions in the field and Are potentially soluble rock topography structures and feasibility of undrained depressions measure size depth and slopes. Dif formations present such as potential site (item 13) ferences in elevation between center limestone, dolomite, or and edges may be almost negligible or gypsum?

many feet. From local residents, attempt to date appearance of Are undrained depressions sinkhole present that cannot be explained by glaciation?

Is surface topography rough and irregular without apparent cause?

Anhydrites or Anhydrites in foundations Determine possible existence from Look for surface evidence of uplift; Are uplifts caused by possible gypsum layers beneath major structures may available geologic information and seek local information on existing anhydrite expansion or hydrate and cause expansion, delineate possible outcrop locations structures ".explosion"?

upward thrust and buckling CA)

Gypsum may cause settlement, Check area carefully for caves or other subsidence, collapse or piping. evidence of solution features Solution during life of structure may be damaging Caves Extent may affect project feasi Observe cave walls carefully for Are any stalactites or bility or cost. Can provide evi evidence of faults and of geologically stalagmites broken from dence regarding faulting that recent faulting. Estimate age of any apparent ground displacement may relate to seismic design. broken stalactites or stalagmites from or shaking?

Can result from unrecorded column rings mining activity in the area Erosion resistance Determines need for total or Locate contacts of potentially Note stability of channels and degree Are channels stable or have partial channel slope protection erosive strata along drainage of erosion and stability of banks they shifted frequently? Are channels banks stable or easily eroded?

Is there extensive bank sliding?

APPENDIX A, Cont'd.

Geologic Feature or Condition Influence on Project Office Studies Field Observations Questions to Answer Internal erosion Affects stability of foundations Locate possible outcrop areas of Examine seepage outcrop areas of and dam abutments. Gravelly sorted alluvial materials or terrace slopes and riverbanks for piping sands or sands with deficiency deposits of intermediate particle sizes may be unstable and develop piping when subject to seepage flow Area subsidence Area subsidence endangers long Locate areas of high groundwater Check project area for new wells or Are there any plans for new or term stability and performance withdrawal, oil fields and subsurface new mining activity increased recovery of of project solution mining of underground subsurface water or mineral mining areas resources?

Collapsing soils Determines need for removal of Determines how deposits were Examine surface deposits for voids Were materials deposited by shallow foundation materials formed during geologic time and any along eroded channels, especially in mud flows?

that would collapse upon collapse problems in area steep valleys eroded in fine-grained wetting sedimentary formations rQ Locally lowered May cause minor to large local Determine if heavy pumping from Obtain groundwater levels in wells groundwater and area settlements and result wells has occurred in project area; from owners and information on in flooding near rivers or open contact city and state agencies and withdrawal rates and any planned water and differential settlement USGS increases. Observe condition of of structures structures. Contact local water plant operators Abnormally low May indicate effective stresses Compare normal groundwater levels Is a possible cause the past pore water are still increasing and may with piezometric levels if data is reduction in vertical stresses pressures (lower cause future slope instability in available (e.g. deep glacial valley or than anticipated valley sites canal excavations such as from groundwater Panama Canal in clay shales levels) where pore water pressures were reduced by stress relief)?

(Continued)

APPENDIX A, Cont'd.

Geologic Feature or Condition Influence on Project Office Studies Field Observations Questions to Answer In situ shear Provides early indication of Locate potential slide areas. Existing Estimate slope angles and heights, Are existing slopes strength from stability of excavated slopes or slope failures should be analyzed to especially at river bends where consistently flat, indicating natural slopes abutment, and natural slopes determine minimum in situ shear undercutting erosion occurs. Deter residual strengths have been around reservoir area strengths mine if flat slopes are associated with developed?

mature slide or slump topography or with erosion features Swelling soils and Highly preconsolidated clays and Determine potential problem and Examine roadways founded on geo Do seasonal groundwater and shales clay shales may swell greatly in location of possible preconsolidated logic formations similar to those at rainfall or watering of shrubs excavations or upon increase in strata from available information site. Check condition of buildings and or trees cause heave or moisture content effects of rainfall and watering settlement?

Varved clays Pervious layers may cause more Determine areas of possible varved Check natural slopes and cuts for rapid settlement than antici clay deposits associated with varved clays; check settlement pated. May appear to be prehis toric lakes. Determine behavior of structures unstable because of uncontrolled settlement 01 seepage flow through pervious behavior of structures in the area layers between overconsolidated clay layers or may have weak clay layers. May be unstable in excavations unless well points are used to control groundwater Dispersive clays A major factor in selecting soils Check with Soil Conservation Look for peculiar erosional features for embankment dams and Service and other agencies such as vertical or horizontal cavities levees regarding behav ior of existing small in slopes or unusual erosion in cut dams slopes. Perform "crumb" test Riverbank and Major effect on riverbank Locate potential areas of loose Check riverbanks for scallop-shaped other liquefaction stability fine-grained alluvial or terrace sand; failure with narrow neck (may be areas and on foundation stability in most likely along riverbanks where visible during low water). If present, seismic areas loose sands are present and erosion determine shape, depth, average is occurring slope and slope of adjacent sections.

Liquefaction in wooded areas may leave trees inclined at erratic angles.

Look for evidence of sand boils in seismic areas

APPENDIX A, Cont'd.

Geologic Feature or Condition Influence on Project Office Studies Field Observations Questions to Answer Filled areas Relatively recent filled areas Check old topo maps if available for Obtain local history of site would cause large settlements. depressions or gullies not shown on from area residents Such fill areas may be more recent topo maps overgrown and not detected from surface or even subsurface evidence Local Local areas of a site may have Obtain local history from overconsolidation been overconsolidated from past residents of area from previous site heavy loadings of lumber or usage material storage piles 0)

APPENDIX B Sources of Geologic Information (EM 1110-1-1804, Department of the Army, 1984)

Type of Agency Information Description Remarks USGS Topographic U.S. 7.5-minute series 1:24,000 (supersedes 1:31,680). Orthophotoquad monocolor maps also produced in maps Puerto Rico 7.5-minute series 1:20,000 (supersedes 1:30,000) Virgin 7.5-minute and 15-minute series. New index of Island 1:24,000 series. maps for each state started in 1976. Status of U.S. 15-minute series 1:62,500 (1:63,360 for Alaska) current mapping from USGS regional offices and in U.S. 1:100,000-scale series (quadrangle, county, or regional format) monthly USGS bulletin, "New publications of the U.S. 1:50,000-scale county map series U.S. Geological Survey" U.S. 1:250,000-scale series Digital elevation models are available for entire U.S. at 1:250,000, and for certain areas at 1:100,000 and 1:24,000 scales.

Digital line graphs are available for some areas at 1:24,000 and 1:65,000 for:

- Hydrography

- Transportation

- U.S. Publication Survey

- Boundaries

- Hypsography USGS Geology maps 1:24,000 (1:20,000 Puerto Rico), 1:62,500, 1:100,00, and New index of geologic maps for each state started in and reports 1:250,000 quadrangle series includes surficial bedrock and standard 1976. List of geologic maps and reports for each (surface and bedrock) maps with major landslide areas shown on later state published periodically editions 1:500,000 and 1:2,500,000 (conterminous U.S., 1974)

USGS Miscellaneous Landslide susceptibility rating, swelling soils, engineering geology, Miscellaneous Investigation Series and maps and water resources, and groundwater Miscellaneous Field Studies Series, maps and reports reports, not well cataloged; many included as open file USGS Special maps 1:7,500,000 and 1:1,000,000: Limestone Resources, Solution Mining Subsidence, Quaternary Dating Applications, Lithologic Map of U.S.,

Quaternary Geologic Map of Chicago, Illinois, and Minneapolis, Minnesota areas USGS Hydrologic Hydrologic Investigations Atlases with a principal map scale of Some maps show groundwater contours and maps 1:24,000; includes water availability, flood areas, surface drainage location of wells precipitation and climate, geology, availability of ground and surface water, water quality and use, and streamflow characteristics (Continued)

APPENDIX B, Cont'd.

Type of Agency Information Description Remarks USGS Earthquake Seismic maps of each state (started in 1978 with Maine); field studies Operates National Strong-Motion Network and hazard of fault zones; relocation of epicenters in eastern U.S.; hazards in the National Earthquake Information Service publishes Mississippi Valley area; analyses of strong motion data; state-of-the monthly listing of epicenters (worldwide).

art workshops USGS Mineral Bedrock and surface geologic mapping; engineering geologic resources investigations; map of power generating plants of U.S. (location of built, under construction, planned, and type); 7.5-minute quadrangle geologic maps and reports on surface effects of subsidence into underground mine openings of eastern Powder River Basin, Wyoming USGS Bibliography "Bibliography of North American Geology" North American, Hawaiian Published until 1972 Islands, and Guam Geological Bibliography "Bibliography and Index of Geology Exclusive of North America" 1934-1968 Society of America "Bibliography and Index of Geology" 1969 to present, 12 monthly issues plus yearly cumulative index 0o NOAA Earthquake National Geophysical Data Center in Colorado contains extensive hazards earthquake hazard information NASA Remote sensing Landsat, Skylab imagery See Table 4-2 of EP 70-1-1 for detailed information data NOAA Remote sensing data EOSAT Remote sensing data USFWS Wetlands The National Wetlands Inventory maps at 1:24,000 for most of the Available as maps or mylar overlays contiguous U.S.

USGS Flood-prone 1:24,000 series maps outlining floodplain areas not included in Corps Stage 2 of 1966 89th Congress House area maps of Engineers reports or protected by levees Document 465 USAEWES Earthquake "State-of-the-Art for Assessing Earthquake Hazards in the United Series of 19 reports, 1973 to present hazard States," Miscellaneous Paper S-73-1 (Continued)

APPENDIX B, Cont'd.

Type of Agency Information Description Remarks International Worldwide Commission for the Geological Map of the World publishes periodic Union of mapping reports on worldwide mapping in "Geological Newsletter" Geological Societies NRCS Soil survey 1:15,840 or 1:20,000 maps of soil information on photomosaic back Reports since 1957 contain engineering uses of reports ground for each country. Recent reports include engineering test data soils mapped, parent materials, geologic origin, for soils mapped, depth to water and bedrock, soil profiles grain-size climate, physiographic setting, and profiles.

distribution, engineering interpretation and special features. Recent aerial photo coverage of many areas. Soils maps at 1:7,500,000, 1:250,000, and 1:12,000 scale are available in digital format for some areas.

FEMA Earthquake NEHRP "Recommended provisions for Seismic Regulations for New hazard Buildings and Older Structures," 1997, includes seismic maps.

State Geologic Geologic maps State and county geologic maps; mineral resource maps; special maps List of maps and reports published annually, rQ Agencies and reports such as for swelling soils; bulletins and monographs; well logs; water unpublished information by direct coordination resources, groundwater studies with state geologist Defense Mapping Topographic Standard scales of 1: 12,500, 1:50,000, 1:250,000 and 1:1,000,000 Index of available maps from DMA Agency (DMA) Maps foreign and worldwide coverage including photomaps American Geological Scale approximately 1 in. equal to 30 miles shows surface geology and Published as 12 regional maps including Alaska Association of highway map includes generalized time and rock unit columns, physiographic map, and Hawaii Petroleum series tectonic map, geologic history summary, and sections Geologists TVA Topographic Standard 7.5-minute TVA-USGS topographic maps, project pool maps, Coordinate with TVA for available specific maps, geologic large-scale topographic maps of reservoirs, geologic maps and reports information maps and in connection with construction projects reports (Continued)

APPENDIX B, Cont'd.

Type of Agency Information Description Remarks USBR Geologic maps Maps and reports prepared during project planning and design studies List of major current projects and project and reports engineers can be obtained. Reports on completed projects by inter-library loan or from USAE Waterways Experiment Station for many dams Agricultural Aerial The APFO offers aerial photographs across the U.S. typically a series of Information is available at 801-975-3503 Stabilization and photograph photographs taken at different times, as available for a given state Conservation Services Aerial Photography Field Office USGS Earth Aerial The EDC houses the nation's largest collection of space and aircraft Information is available at 605-594-6151 or Resources photographic acquired imagery 800 USAMAPS Observation coverage C&O Systems (EROS) 0 Data Center (EDC)

SPOT Remote sensing High resolution multispectral imagery produced by France's SPOT Contact for SPOT images is at 800-275-7768 imagery satellite imager is available for purchase

APPENDIX C METHODS OF SUBSURFACE EXPLORATION METHOD PROCEDURE APPLICABILITY LIMITATIONS

1. Methods of Access for Sampling, Test, or Observation Pits, Trenches, Shafts, Excavation made by hand, large Visual Observation, photography, disturbed Depth of unprotected excavations is limited by groundwater Tunnels auger, or digging machinery and undisturbed sampling, in situ testing or safety considerations. May need dewatering.

of soil and rock.

Auger Boring Boring advanced by hand auger Recovery of remolded samples and determining Will not penetrate boulders or most rock.

or power auger. groundwater levels. Access for undisturbed sampling of cohesive soils.

Hollow Stem Auger Boring advanced by means of Access to undisturbed or representative Should not be used with plug in coarse-grained soils.

Boring continuous-flight helix auger sampling through hollow stem with thin-wall Not suitable for undisturbed sampling in loose sand or silt.

with hollow-center stem. tube sampler, core barrel, or split-barrel sampler.

Wash Boring Boring advanced by chopping with Cleaning out and advancing hole in soil Suitable for use with sampling operations in soil only if done light bit and by jetting with upward between sample intervals. with low water velocities and with upward deflected jet.

deflected jet.

Rotary Drilling Boring advanced by rotating drilling Boring in soil or rock. Drilling mud should be used in coarse-grained soils. Bottom bit; cuttings removed by circulating discharge bits are not suitable for use with undisturbed drilling fluid. sampling in soil unless combined with protruding core barrel, as in Denison sampler, or with upward deflected jets.

Percussion Drilling Boring advanced by air-operated Detection of voids and zones of weakness in Not suitable for use in soils.

impact hammer. rock by changes in drill rate or resistance.

Access for in situ testing or logging.

Cable Drilling Boring advanced by repeated Advancing hole in soil or rock. Access for sampling, Causes severe disturbance in soils; not suitable for use with dropping of heavy bit; removal of in situ testing, or logging in rock. Penetration of undisturbed sampling methods.

cuttings by bailing. hard layers, gravel, or boulders in auger borings.

Continuous Sampling or Boring advanced by repeated pushing of Recovery of representative samples of cohesive Effects of advance and withdrawal of sampler result in disturbed Displacement Boring sampler, or closed sampler is pushed to soils and undisturbed samples in some cohesive sections at top and bottom of sample. In some soils, entire desired depth and sample is taken. soils. sample may be disturbed. Best suited for use in cohesive soils.

Continuous sampling in cohesionless soils may be made by successive reaming and cleaning of hole between sampling.

APPENDIX C, Cont'd.

METHOD PROCEDURE APPLICABILITY LIMITATIONS

2. Methods of Sampling Soil or Rock Hand Cut Block or Sample is cut by hand from soil Highest quality samples in all soils and Requires accessible excavation and dewatering, if below Cylindrical Sample exposed in excavation. in soft rock. water table. Extreme care is required in sampling cohesionless soils.

Fixed-Piston Sampler Thin-walled tube is pushed into soil, Undisturbed samples in cohesive soils, silts, Some types do not have a positive means to prevent with fixed piston in contact with top and sands above or below the water table. Piston movement.

of sample during push.

Hydraulic Piston Sampler Thin-walled tube is pushed into soil by Undisturbed samples in cohesive soils, silts, Not possible to determine amount of sampler penetration (Osterberg Sampler) hydraulic pressure. Fixed piston in and sands above or below the water table. during push. Does not have vacuum breaker in piston.

contact with top of sample during push.

Free-Piston Sampler Thin-walled tube is pushed into soil. Undisturbed samples in stiff, cohesive soils. May not be suitable for sampling in cohesionless soils.

Piston rests on top of soil sample Representative samples in soft to medium Free piston provides no control of specific recovery ratio.

during push. cohesive soils and silts.

Open Drive Sampler Thin-walled open tube is pushed Undisturbed samples in stiff, cohesive soils. Small diameter of tubes may not be suitable for sampling into soil. Representative samples in soft to medium in cohesionless soils or for undisturbed sampling in cohesive soils and silts. uncased boreholes. No control of specific recovery ratio.

N*

Swedish Foil Sampler Sample tube is pushed into soil, while Continuous undisturbed samples up to 20 m Not suitable for in soils containing gravels, sand layers, or stainless steel strips unrolling from spools (66 feet) long in very soft to soft clays. shells, which may rupture foils and damage samples. Difficulty envelop sample. Piston, fixed by chain may be encountered in alternating hard and soft layers, with from surface, maintains contact with squeezing of soft layers and reduction in thickness. Requires top of sample. experienced operator.

Pitcher Sampler Thin-walled tube is pushed into soil by Undisturbed samples in stiff, hard, brittle, cohesive Frequently ineffective in cohesionless soils.

spring above sampler, while outer core soils and sands with cementation, and in soft rock.

bit reams hole. Cuttings removed by Effective in sampling alternating hard and soft layers.

circulating drilling fluid. Representative samples in soft-to-medium cohesive soils and silts. Disturbed samples may be obtained in cohesionless materials with variable success.

Split-Barrel or Split Split-barrel tube is driven into soil by Representative samples in soils other than Samples are disturbed and not suitable for tests of Spoon Sampler blows of falling ram. Sampling is carried coarse-grained soils. physical properties.

out in conjunction with Standard Penetration Test.

Auger Sampling Auger drill used to advance hole is Determine boundaries of soil layers and obtain Samples not suitable for physical property or density tests.

withdrawn at intervals for recovery of samples of soil classification. Large errors in locating strata boundaries may occur without soil samples from auger flights. close attention to details of procedure. In some soils, particle breakdown by auger or sorting effects may result in errors in Determining gradation.

APPENDIX C, Cont'd.

METHOD PROCEDURE APPLICABILITY LIMITATIONS

2. Methods of Sampling Soil or Rock (Continued)

Rotary Core Barrel Hole is advanced by core bit while core Core samples in competent rock and hard soils Because recovery is poorest in zones of weakness, samples sample is retained within core barrel or with single tube core barrel. Core samples in poor generally fail to yield positive information on soft seams, joints, within stationary inner tube. Cuttings or broken rock may be obtainable with double tube or other defects in rocks.

removed by drilling fluid. core barrel with bottom discharge bit.

Denison Sampler Hole is advanced and reamed by core Undisturbed samples in stiff-to-hard cohesive soil, Not suitable for undisturbed sampling in loose, cohesionless drill while sample is retained in non- sand with cementation, and soft rocks. Disturbed soils or soft, cohesive soils. Difficulties may be experienced in rotating inner core barrel with corecatcher. sample may be obtained in cohesionless materials sampling alternating hard and soft layers.

Cuttings removed by circulating drilling with variable success.

fluid.

Shot Core Boring (Calyx) Boring advanced by rotating single core Large diameter cores and accessible boreholes Cannot be used in drilling at large angles to the vertical. Often barrel, which cuts by grinding with chilled in rock. ineffective in securing small diameter cores.

steel shot fed with circulating wash water.

Used shot and coarser cuttings are deposited in an annular cup, or calyx, CA3 above the core barrel.

Oriented Integral Sampling Reinforcing rod is grouted into small Core samples in rock with preservation of joints Samples are not well suited to tests of physical properties.

diameter hole, then overcored to obtain and other zones of weakness.

an annular core sample.

Wash Sampling or Cuttings are recovered from wash Samples useful in conjunction with other data Sample quality is not adequate for site investigations for Cuttings Sampling water or drilling fluid. for identification of major strata. nuclear facilities.

Submersible Vibratory Core tube is driven into soil by Continuous representative samples in Because of high area ratio and effects of vibration, samples (Vibracore) Sampler vibrator. unconsolidated marine sediments. may be disturbed.

Underwater Piston Corer Core tube attached to drop weight is Representative samples in unconsolidated Samples may be seriously disturbed. Cable supported piston driven into soil by gravity after a free marine sediments. remains in contact with soil surface during drive.

fall of controlled height.

Gravity Corer Open core tube attached to drop weight Representative samples at shallow depth in No control of specific recovery ratio. Samples are disturbed.

is driven into soil by gravity after free fall. unconsolidated marine sediments.

APPENDIX C, Cont'd.

METHOD PROCEDURE APPLICABILITY LIMITATIONS

3. Methods of In Situ Testing of Soil and Rock Standard Penetration Test Split-barrel sampler is driven into soil Blow count may be used as an index of consistency Extremely unreliable in silts, silty sands, or soils containing by blows of free falling weight. Blow or density of soil. May be used for detection of gravel. In sands below water table, positive head must be count for each 15 cm (6 in.) of changes in consistency or density in clays or sands. maintained in borehole, Determination of relative density in penetration is recorded. May be used with empirical relationships to estimate sands requires site-specific correlation or highly conservative relative density of clean sand. use of published correlations. Results are sensitive to details of apparatus and procedure.

Cone Penetrometer Test Steel cone is pushed into soil and Detection of changes in consistency or relative Strength estimates require on site verification of by other followed by subsequent advance of density in clays or sands. Used to estimate static methods of testing.

friction sleeve. Resistance is measured undrained shear strength of clay. Used with during both phases of advance. empirical relationships to obtain estimate of static compressibility of sand.

Field Vane Shear Test Four-bladed vane is pushed into Used to estimate in situ undrained shear strength Not suitable for use in silts, sands, or soils containing undisturbed soil, then rotated to cause and sensitivity of clays. appreciable amounts of gravel or shells. May yield shear failure on cylindrical surface. unconservative estimates of shear strength in fissured clay Torsional resistance versus angular soils or where strength is strain-rate dependent.

deflection is recorded.

(A), Drive Point Penetrometer Expandable steel cone is driven into Detection of gross changes in consistency or relative Provides no quantitative information on soil properties.

-Ph soil by falling weight. Blow count density. May be used in some coarse-grained soils.

versus penetration is recorded.

Plate Bearing Test (Soil) Steel loading plate is placed on horizontal Estimation of strength and moduli of soil. May be Results can be extrapolated to loaded areas larger than surface and is statically loaded, usually by used at ground surface, in excavations, or in bearing plate only if properties of soil are uniform laterally hydraulic jack. Settlement versus time is boreholes. and with depth.

recorded for each load increment.

Plate Bearing Test or Bearing pad on rock surface is statically Estimation of Elastic moduli of rock masses. May Results can be extrapolated to loaded areas larger than Plate Jacking Test (Rock) loaded by hydraulic jack. Deflection be used at ground surface, in excavations, in bearing pad only if rock properties are uniform over volume of versus load is recorded. tunnels, or in boreholes. interest, and if diameter of bearing pad is larger than average spacing of joints or other discontinuities.

Pressure Meter Test Uniform radial pressure is applied Estimation of elastic moduli of rocks and estimation Test results represent properties only of materials in vicinity (Dilatometer Test) hydraulically over a length of borehole of shear strengths and compressibility of soils by of borehole. Results may be misleading in testing materials several times its diameter. Change in empirical relationships. whose properties may be anisotropic.

diameter versus pressure is recorded.

Field Pumping Test Water is pumped from or into an aquifer Estimation of in situ permeability of soils and rock Apparent permeability may be greatly influenced by local at constant rate through penetrating well. mass. features. Effective permeability of rock is dependent Change in piezometric level is measured primarily on frequency and distribution of joints. Test result at well and at one or more observation in rock is representative only to the extent that the borehole wells. Pumping pressures and flow rates intersects a sufficient number of joints to be representative of are recorded. Packers may be used for the joint system of the rock mass.

Pump-in pressure tests.

APPENDIX C, Cont'd.

METHOD PROCEDURE APPLICABILITY LIMITATIONS

3. Methods of In Situ Testing of Soil and Rock (Continued)

Borehole Field Permeability Water is added to an open-ended pipe Rough approximation of in situ permeability of Pipe casing must be carefully cleaned out just to the bottom Test casing sunk to desired depth. With soils and rock mass. of the casing. Clear water must be used or tests may be constant head tests, constant rate of grossly misleading. Measurement of local permeability only.

gravity flow into hole and casing pipe are measured. Variations include applied pressure tests and falling head tests.

Direct Shear Test Block of in situ rock is isolated to permit Measurement of shearing resistance of rock Tests are costly. Usually, variability of rock mass requires a shearing along a preselected surface. mass in situ. sufficient number of tests to provide statistical control.

Normal and shearing loads are applied by Jacking. Loads and displacements are recorded.

Pressure Tunnel Test Hydraulic pressure is applied to sealed-off Determination of elastic constants of the rock Volume of rock tested is dependent on tunnel diameter.

length of circular tunnel, and diametral mass in situ. Cracking due to tensile hoop stresses may affect apparent deformations are measured. stiffness of rock.

Radial Jacking Test Radial pressure is applied to a length of Same as pressure tunnel test. Same as pressure tunnel test.

circular tunnel by flat jacks. Diametral (A) deformations are measured.

C-"

Borehole Jack Test Load is applied to wall of borehole by two Determination of elastic modulus of rock in situ. Apparent stiffness may be affected by development of tension diametrically opposed jacks. Deformations Capable of applying greater pressure than cracks.

and pressures are recorded, dilatometers.

Borehole Deformation Meter Device for measuring diameters is placed Measurement of absolute stresses in situ. Stress field is affected by borehole. Analysis subject to in borehole, and hole is overcored to limitations of elastic theory. Two boreholes at different relieve stresses on annular rock core with orientations are required for determination of complete stress deformation meter. Diameters (usually 3) field. Questionable results in rocks with strongly time are measured before and after overcoring. dependent properties.

Rock modulus is measured by laboratory tests on core; in situ stresses are computed by elastic theory.

Inclusion Stressmeter Rigid stress indicating device (stressmeter) Measurement of absolute stressed in situ. Does Same as above.

is placed in borehole, and hole is overcored not require accurate knowledge of rock modulus.

to relieve stresses on annular core with stress meter. In situ stresses are computed by elastic theory.

Borehole Strain Gauge Strain gauge is cemented to bottom of Measurement of absolute stresses in situ. Same as above.

borehole, and gauge is overcored to Requires only one core drill size.

relieve stresses on core containing strain gauge. Stresses are computed from resulting strains and from modulus obtained by laboratory tests on core.

APPENDIX C, Cont'd.

METHOD PROCEDURE APPLICABILITY LIMITATIONS

3. Methods of In Situ Testing of Soil and Rock (Continued)

Flat Jack Test Slot Is drilled in rock surface, producing Measurement of one component of normal Stress field affected by excavation or tunnel used.

stress relief in adjacent rock. Flat jack is stress in situ. Does not require knowledge Interpretation of test results subject to assumption that grouted into slot and hydraulically of rock modulus. loading and unloading moduli are equal. Questionable results pressurized. Pressure required to reverse in rock with strongly time-dependent properties.

deformations produced by stress relief Is observed.

Hydraulic Fracturing Test Fluid is pumped into sealed-off portion of Estimation of minor principal stress. Affected by anisotropy of tensile strength in rock.

borehole with pressure increasing until fracture occurs.

Crosshole Seismic Test Seismic signal is transmitted from source in In situ measurement of compression wave velocity Requires deviation survey of boreholes to eliminate errors one borehole to receiver(s) in other and shear wave velocity in soils and rocks due to deviation of holes from vertical. Refraction of signal borehole(s), and transit time is recorded. through adjacent high-velocity beds must be considered.

Uphole/Downhole Seismic Seismic signal is transmitted between In situ measurement of compression wave velocity Apparent velocity obtained is time-average for all strata Test borehole and and ground surface, and and shear wave velocity in soils and rocks. between source and receiver.

transit time is recorded.

(4 Acoustic Velocity Log Logging tool contains transmitting and two Measurement of compression wave velocity. Results represent only the material immediately adjacent to receiving transducers separated by fixed Used primarily in rocks to obtain estimate of the borehole. Can be obtained only in uncased, fluid-filled gauge length. Signal is transmitted through porosity. borehole. Use is limited to materials with P-Wave velocity rock adjacent to borehole, and transit time greater than that of the borehole fluid.

over the gauge length is recorded as the difference in arrival times at the receivers.

3-D Velocity Log Logging tool contains transmitting and Measurement of compression wave and shear Results represent only the material immediately adjacent to receiving transducer separated by fixed wave velocities in rock. Detection of void spaces, the borehole. Can be obtained only in uncased, fluid-filled gauge length. Signal is transmitted open fractures, and zones of weakness. borehole. Correction required for variation in hole size. Use through rock adjacent to borehole, and is limited to materials with P-wave velocity greater than that wave train at receiver is recorded. of borehole fluid.

Electrical Resistivity Log Apparent electrical resistivity of soil or Appropriate combination of resistivity logs can be Can be obtained only in uncased boreholes. Hole must be fluid rock in neighborhood of borehole is used to estimate porosity and degree of water filled, or electrodes must be pressed against borehole.

measured by in-hole logging tool saturation in rocks. In soils, may be used as Apparent resistivity values are strongly affected by changes in containing one of a wide variety of qualitative indication of changes in void ratio or hole diameter, strata thickness, resistivity contrast between electrode configurations. water content, for correlation of strata between adjacent strata, resistivity of drilling fluid, etc.

boreholes, and for location of strata boundaries.

Neutron Log Neutrons are emitted into rock or soil Correlation of strata between boreholes and Because of very strong borehole effects, results are generally around borehole by a neutron source in location of strata boundaries. Provides an not of sufficient accuracy for quantitative engineering uses.

the logging tool. A detector, isolated from approximation to water content and can be run the source, responds to either slow in cased or uncased, fluid filled or empty boreholes.

neutrons or secondary gamma rays.

Response of detector is recorded.

APPENDIX C, Cont'd.

METHOD PROCEDURE APPLICABILITY LIMITATIONS

3. Methods of In Situ Testing of Soil and Rock (Continued)

Gamma-Gamma Log Gamma rays are emitted into rock Estimation of bulk density in rock, qualitative Effects of borehole size and density of drilling fluid must be (Density Log) around the borehole by a source in the indication of changes of density in soils. accounted for. Presently not suitable for qualitative estimate logging tool, and a detector isolated May be run in empty or fluid filled holes. of density in soils other than those of "rock-like" character.

from the source responds to back Cannot be used in cased boreholes.

scattered gamma rays. Response of detector is recorded.

Borehole Cameras Film-type or television camera in a Detection and mapping of joints, seams, cavities, Results are affected by any condition that impairs visibility.

suitable protective container is used or other visually observable features in rock. Can for observation of walls of borehole, be used in empty, uncased holes, or in boreholes filled with clear water.

Borehole Televiewer A rotating acoustic signal illuminates Detection and mapping of joints, seams, cavities, Transparency of borehole fluid is not essential.

the borehole wall, and reflected signals or other observable features in rock. Can be used are recorded. in mud-filled boreholes.

W,

-.4

APPENDIX D SPACING AND DEPTH OF SUBSURFACE EXPLORATIONS FOR SAFETY-RELATED 2 FOUNDATIONS STRUCTURE SPACING OF BORINGS 3 OR SOUNDINGS MINIMUM DEPTH OF PENETRATION General For favorable, uniform geologic conditions, where The depth of borings should be determined on the basis of the type continuity of subsurface strata is found, the of structure and geologic conditions. All borings should be extended recommended spacing is as indicated for the type to a depth sufficient to define the site geology and to sample all of structure. At least one boring should be at the materials that may swell during excavation, may consolidate subse location of every safety-related structure. Where quent to construction, may be unstable under earthquake loading or variable conditions are found, spacing should be whose physical properties would affect foundation behavior or smaller, as needed, to obtain a clear picture of stability. Where soils are very thick, the maximum required depth soil or rock properties and their variability. Where for engineering purposes, denoted dm, mx, may be taken as the depth at cavities or other discontinuities of engineering which the change in the vertical stress during or after construction significance may occur, the normal exploratory for the combined foundation loading is less than 10% of the work should be supplemented by borings or effective in situ overburden stress. It may be necessary to include soundings at a spacing small enough to detect in the investigation program several borings to establish the soil 03 W0 such features. model for soil-structure interaction studies. These borings may be required to penetrate depths greater than those required for general engineering purposes. Borings should be deep enough to define and evaluate the potential for deep stability problems at the site.

Generally, all borings should extend at least 10 M (33 ft) below the lowest part of the foundation. If competent rock is encountered at lesser depths than those given, borings should penetrate to the greatest depth where discontinuities or zones of weakness or alteration can affect foundations and should penetrate at least 6 m (20 ft) into sound rock. For weathered shale or soft rock, depths should be as for soils.

2 As determined by the final locations of safety-related structures and facilities.

3 Includes shafts or other accessible excavations that meet depth requirements.

Appendix D, Continued STRUCTURE SPACING OF BORINGS OR SOUNDINGS MINUMUM DEPTH OF PENETRATION Buildings, Principal borings: at least one boring beneath At least one-fourth of the principal borings and a minimum of retaining every safety-related structure. For larger, one boring per structure to penetrate into sound rock or to a walls, heavier structures, such as the containment depth equal to drlmx. Others to a depth below foundation concrete and auxiliary buildings, at least one boring per elevation equal to the width of structure or to a depth equal to dams 900 m 2 (10,000 ft 2) (approximately 30 m the width of the structure or to a depth equal to the foundation (100 ft) spacing). In addition, a number of depth below the original ground surface, whichever is greater.'

borings along the periphery, at corners, and other selected locations. One boring per 30 m (100 ft) for essentially linear structures.

Earth dams, Principal borings: one per 30 m (100 ft) along Principal borings: one per 60 m (200 ft) to dmax. Others dikes, axis of structure and at critical locations should penetrate all strata whose properties would affect the levees, perpendicular to the axis to establish geological performance of the foundation. For water-impounding embank sections with groundwater conditions for structures, to sufficient depth to define all aquifers and zones C ments analysis. 3 of underseepage that could affect the performance of structures.3 Deep cuts,5 Principal borings: one per 60 m (200 ft) along Principal borings: One per 60 m (200 ft) to penetrate into canals the alignment and at critical locations sound rock or to dmax. Others to a depth below the bottom perpendicular to the alignment to establish elevation of excavation equal to the depth of cut or to below geologic sections with groundwater conditions the lowest potential failure zone of the slope.3 Borings should for analysis. 3 penetrate pervious strata below which ground-water may influence stability. 3 4

Also supplementary borings or soundings that are design-dependent or necessary to define anomalies, critical conditions, etc.

5 Includes temporary cuts that would affect ultimate site safety.

Appendix D, Continued STRUCTURE SPACING OF BORINGS OR SOUNDINGS MINUMUM DEPTH OF PENETRATION Pipelines Principal borings: This may vary depending Principal borings: For buried pipelines, one of every three to on how well site conditions are understood penetrate sound rock or to drmax. Others to 5 times the pipe from other plant site borings. For variable diameters below the elevation. For pipelines above ground, conditions, one per 30 m (100 ft) for buried depths as for foundation structures.3 pipelines; at least one boring for each footing for pipelines above ground.

Tunnels Principal borings: one per 30 m (100 ft),3 may Principal borings: one per 60 m (200 ft) to penetrate into vary for rock tunnels, depending on rock type sound rock or to d,,,. Others to 5 times the tunnel diameter and characteristics and planned exploratory below the invert elevation.3 '4 shafts or adits.

Reservoirs, Principal borings: In addition to borings at the Principal borings: At least one-fourth to penetrate that portion 4h. impound locations of dams or dikes, a number of of the saturation zone that may influence seepage conditions o ments borings should be used to investigate geologic or stability. Others to a depth of 7.5 m (25 ft) below reservoir conditions of the reservoir basin. The number bottom elevation. 3 and spacing of borings should vary, with the largest concentration near control structures and the coverage decreasing with distance upstream.

Sounding = An exploratory penetration below the ground surface used to measure or observe an in situ property of subsurface materials, usually without recovery of samples or cuttings.

Principal boring = A borehole used as a primary source of subsurface information. It is used to explore and sample all soil or rock strata penetrated to define the site geology and the properties of subsurface materials. Not included are borings from which no samples are taken, borings used to investigate specific or limited intervals, or borings so close to others that information obtained represents essentially a single location.

APPENDIX E Applications of Selected Geophysical Methods for Determination of Engineering Parameters Geophysical Method Basic Measurement Application Advantages Limitations Surface Refraction (seismic) Travel time of Velocity determination of Rapid, accurate, and relatively Rapid, accurate, and relatively economical compressional waves compression wave through economical technique. technique. Interpretation theory generally through subsurface subsurface. Depths to Interpretation theory generally straightforward and equipment readily available. In layers contrasting interfaces and straightforward and equipment saturated soils, the compression wave velocity geologic correlation of readily available. reflects mostly wave velocities in the water, and horizontal layers. thus is not indicative of soil properties.

Reflection (seismic) Travel time of Mapping of selected Rapid, thorough coverage of Rapid, thorough coverage of given site area. Data compressional waves reflector horizons. Depth given site area. Data displays displays highly effective. In saturated soils, the reflected from determinations, fault highly effective. compression wave velocity reflects mostly wave subsurface layers detection, discontinuities, velocities in the water, and thus is not indicative of and other anomalous soil properties.

features.

Rayleigh wave Travel time and period Inference of shear wave Rapid technique which uses Rapid technique which uses conventional refraction dispersion of surface Rayleigh velocity in near-surface conventional refraction seismographs.

waves materials. seismographs.

Vibratory (seismic) Travel time or Inference of shear wave Controlled vibratory source Controlled vibratory source allows selection of wavelength of surface velocity in near-surface allows selection of frequency, frequency, hence wavelength and depth of Rayleigh waves materials. hence wavelength and depth of penetration [up to 60 m (200 ft)]. Detects low penetration [up to 60 m velocity zones underlying strata of higher velocity.

(200 ft)]. Detects low-velocity Accepted method.

zones underlying strata of higher velocity. Accepted method.

Reflection profiling Travel times of Mapping of various Surveys of large areas at Data resolution and penetration capability is (seismic-acoustic) compressional waves lithologic horizons; detection minimal time and cost; frequency dependent; sediment layer thickness through water and of faults, buried stream continuity of recorded data and/or depth to reflection horizons must be subsurface materials channels, and salt domes, allows direct correlation of considered approximate unless true velocities are and amplitude of location of buried man-made lithologic and geologic changes; known; some bottom conditions (e.g., organic reflected signal objects; and depth correlative drilling and coring sediments) prevent penetration; water depth should determination of bedrock or can be kept to a minimum. be at least 5 to 6 m (15 to 20 ft) for proper system other reflecting horizons. operation.

(Continued)

APPENDIX E, Cont'd.

Geophysical Method Basic Measurement Application Advantages Limitations Surface (Continued)

Electrical resistivity Electrical resistance of Complementary to Economical nondestructive Lateral changes in calculated resistance often a volume of material refraction (seismic). Quarry technique. Can detect large interpreted incorrectly as depth related; hence, for between probes rock, groundwater, sand bodies of "soft" materials, this and other reasons, depth determinations can be and gravel prospecting. grossly in error, Should be used in conjunction with River bottom studies and other methods, i.e., seismic.

cavity detection.

Acoustic Amplitude of Traces (on ground surface) Rapid and reliable method. Must have access to some cavity opening. Still in (resonance) acoustically coupled lateral extent of cavities. Interpretation relatively experimental stage - limits not fully established.

sound waves straightforward. Equipment originating in an air- readily available.

filled cavity Ground penetrating Travel time and Rapidly profiles layering Very rapid method for shallow Transmitted signal rapidly attenuated by water.

radar(GPR) amplitude of a conditions. Stratification, site investigations. On line Severely limits depth of penetration. Multiple reflected dip, water table, and digital data processing can yield reflections can complicate data interpretation.

t.3 electromagnetic wave presence of many types of "on site" look. Variable density anomalies can be display highly effective.

determined.

Gravity Variations in Detects anticlinal structures, Provided extreme care is Equipment very costly. Requires specialized gravitational field buried ridges, salt domes, exercised in establishing personnel. Anything having mass can influence faults, and cavities, gravitational references, data (buildings, automobiles, etc). Data reduction reasonably accurate results can and interpretation are complex. Topography and be obtained, strata density influence data.

Magnetic Variations of earth's Determines presence and Minute quantities of magnetic Only useful for locating magnetic materials.

magnetic field location of magnetic or materials are detectable. Interpretation highly specialized. Calibration on site ferrous materials in the extremely critical. Presence of any ferrous objects subsurface. Locates ore influences data.

bodies.

Borehole Uphole/downhole Vertical travel time of Velocity determination of Rapid technique useful to define Care must be exercised to prevent undesirable (seismic) compressional and/or vertical P- and/or S-waves. low- velocity strata. influence of grouting or casing shear waves Identification of low-velocity Interpretation straightforward.

zones.

APPENDIX E, Cont'd.

Geophysical Method Basic Measurement Application Advantages Limitations Borehole (Continued)

Crosshole (seismic) Horizontal travel time Velocity determination of Generally accepted as producing Careful planning with regard to borehole spacing of compressional horizontal P- and/or S- reliable results. Detects low- based upon geologic and other seismic data an and/or shear waves waves. Elastic velocity zones provided borehole absolute necessity. Shell's law of refraction must characteristics of sub- spacing not excessive, be applied to establish zoning. A borehole deviation surface strata can be survey must be run. Requires highly experienced calculated. personnel. Repeatable source required.

Borehole Natural earth potential Correlates deposits, locates Widely used, economical tool. Log must be run in a fluid filled, uncased boring.

spontaneous water resources, studies Particularly useful in the Not all influences on potentials are known.

potential rock deformation, assesses identification of highly porous permeability, and strata (sand, etc.).

determines groundwater salinity.

Single-point Strata electrical In conjunction with Widely used, economical tool. Strata resistivity difficult to obtain. Log must be resistivity resistance adjacent to spontaneous potential, Log obtained simultaneous with run in a fluid filled, uncased boring. Influenced by CA) a single electrode correlates strata and locates spontaneous potential., drill fluid.

porous materials.

Long and short- Near-hole electrical Measures resistivity within a Widely used, economical tool. Influenced by drill fluid invasion. Log must be run normal resistivity resistance radius of 40 to 165 cm (16 in a fluid filled, uncased boring.

to 64 in).

Lateral resistivity Far-hole electrical Measures resistivity within a Less drill fluid invasion influence. Log must be run in a fluid filled, uncased boring.

resistance radius of 6 m (20 ft). Investigation radius limited in low moisture strata.

Induction resistivity Far-hole electrical Measures resistivity in air- Log can be run in a Large, heavy tool.

resistance or oil-filled holes. nonconductive casing.

Borehole imagery Sonic image of Detects cavities, joints, Useful in examining casing Highly experienced operator required. Slow log to (acoustic) borehole wall fractures in borehole wall, interior. Graphic display of obtain. Probe awkward and delicate.

Determine attitude (strike images. Fluid clarity immaterial.

and dip) of structures.

(Continued)

APPENDIX E, Cont'd.

Geophysical Method Basic Measurement Application Advantages Limitations Borehole (Continued)

Continuous sonic Time of arrival of P- Determines velocity of P- Widely used method. Rapid and Shear wave velocity definition questionable in (3-D) velocity and S-waves in high- and S-waves in near vicinity relatively economical. Variable unconsolidated materials and soft sedimentary velocity materials of borehole. Potentially density display generally rocks. Only P-wave velocities greater than 1500 useful for cavity and impressive. Discontinuities in" m/s (5,000 fps) can be determined.

fracture detection. Modulus strata detectable.

determinations. Sometimes S-wave velocities are inferred from P-wave velocity and concurrently run nuclear logs through empirical correlations.

Natural gamma Natural radioactivity Lithology, correlation of Widely used, technically simple Borehole effects, slow logging speed, cannot radiation strata, may be used to infer to operate and interpret. directly identify fluid, rock type, or porosity.

permeability. Locates clay Assumes clay minerals contain potassium strata and radioactive 40 isotope.

minerals.

Gamma-gamma Electron density Determines rock density of Widely used. Can be applied to Borehole effects, calibration, source intensity, density subsurface strata. quantitative analyses of chemical variation in strata affect measurement engineering properties. Can precision. Radioactive source hazard.

provide porosity.

Neutron porosity Hydrogen content Moisture content (above Continuous measurement of Borehole effects, calibration, source intensity, water table) total porosity porosity. Useful in hydrology and bound water, all affect measurement precision.

(below water table). engineering property Radioactive source hazard.

determinations. Widely used.

Neutron activation Neutron capture Concentration of selected Detects elements such as U, Na, Source intensity, presence of two or more elements radioactive materials in Mn. Used to determine oil-water having similar radiation energy affect data.

strata. contact (oil industry) and in prospecting for minerals (Al, Cu).

Borehole magnetic Nuclear precession Deposition, sequence, and Distinguishes ages of Earth field reversal intervals under study. Still age of strata. lithologically identical strata. subject of research.

Mechanical caliper Diameter of borehole Measures borehole Useful in a wet or dry hole. Must be recalibrated for each run. Averages diameter. 3 diameters.

APPENDIX E, Cont'd.

Geophysical Method Basic Measurement Application Advantages Limitations Borehole (Continued)

Acoustic caliper Sonic ranging Measures borehole Large range. Useful with highly Requires fluid filled hole and accurate positioning.

diameter. irregular shapes.

Temperature Temperature Measures temperature of Rapid, economical, and generally None of importance.

fluids and borehole accurate.

sidewalls. Detects zones of inflow or fluid loss.

Fluid resistivity Fluid electrical Water-quality Economical tool. Borehole fluid must be same as groundwater.

resistance determinations and auxiliary log for rock resistivity, Tracers Direction of fluid flow Determines direction of fluid Economical tool. Environmental considerations often preclude use of flow. radioactive tracers.

Flowmeter Fluid velocity and Determines velocity of Interpretation is simple. Impeller flowmeters usually cannot measure flows (31 quantity subsurface fluid flow and, in less than 1 to 1.7 cm/s (2 - 3 ft/min).

most cases, quantity of flow.

Borehole dipmeter Sidewall resistivity Provides strike and dip of Useful in determining Expensive log to make. Computer analysis of bedding planes. Also used information on the location and information needed for maximum benefit.

for fracture detection. orientation of primary sedimentary structures over a wide variety of hole conditions.

Borehole surveying Azimuth and Determines the amount and A reasonably reliable technique. Errors are cumulative, so care must be taken at declination of borehole direction of borehole Method must be used during the each measurement point to achieve precise data.

drift deviation from the vertical conduct of crosshole surveys to normal. determine distance between seismic source and receivers.

Downhole flow Flow across the Determines the rate and A reliable, cost effective method Assumes flow not influenced by emplacement of meter borehole direction of groundwater to determine lateral foundation borehole.

flow. leakage under concrete structures.

APPENDIX F IN SITU TESTING METHODS Table F-I In Situ Tests for Rock and Soil (adapted from EM 1110-1-1804, Department of the Army, 1984)

Applicability to Purpose of Test Type of Test Soil Rock Shear strength Standard penetration test (SPT) X Field vane shear X Cone penetrometer test (CPT) X Direct shear X X Xa Plate bearing or jacking Borehole direct shearb x Pressuremeterb x Uniaxial compressiveb x Borehole jackingb x Plate bearing X Xa Bearing capacity Standard penetration X Stress conditions Hydraulic fracturing X X X Xa Pressuremeter Overcoring X Flatjack X Uniaxial (tunnel) jacking X X Borehole jackingb X Chamber (gallery) pressureb X Mass deformability Geophysical (refraction) X X Pressuremeter or dilatometer X Xa Plate bearing X X Standard penetration X Uniaxial (tunnel) jacking X X Borehole jackingb x Chamber (gallery) pressureb x Relative density Standard penetration X In situ sampling X Liquefaction susceptibility Standard penetration X Cone penetrometer test (CPT) X Shear wave velocity (vJ) a Primarily for clay shales, badly decomposed, or moderately soft rocks, and rock with soft seams.

b Less frequently used.

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APPENDIX F, Cont'd.

Table F-2 In Situ Tests to Determine Shear Strength (adapted from EM 1110-1-1804, Department of the Army, 1984)

For Test Soils Rocks Remarks Standard penetration X Use as index test only for strength. Develop local correlations. Unconfined compressive strength in tsf is often 1/6 to 1/8 of N-value Direct shear '. Rock X X Expensive; use when representative Testing Handbook. undisturbed samples cannot be obtained Field vane shear X Use strength reduction factor Plate bearing X X Evaluate consolidation effects that may occur during test Uniaxial compression X Primarily for weak rock; expensive since several sizes of specimens must be tested Cone penetrometer X Consolidated undrained strength of clays; test (CPT) requires estimate of bearing factor, N,..

Table F-3 In Situ Tests to Determine Stress Conditions (adapted from EM 1110-1-1804, Department of the Army, 1984)

Test Soils Rocks Remarks Hydraulic fracturing X Only for normally consolidated or slightly consolidated soils Hydraulic fracturing X Stress measurements in deep holes for tunnels Vane shear X Only for recently compacted clays, silts and fine sands (see Blight, 1974, for details and limitations)

Overcoring X Usually limited to shallow depth in rock techniques Flatjacks X Uniaxial X X May be useful for measuring lateral (tunnel) jacking stresses in clay shales and rocks, also in soils 47

APPENDIX F, Cont'd.

Table F-4 In Situ Tests to Determine Deformation Characteristics (adapted from EM 1110-1-1804, Department of the Army, 1984)

For Test Soils Rocks Remarks Geophysical X X For determining dynamic Young's Modulus, E, at the refraction, small strain induced by test procedure. Test values for cross E must be reduced to values corresponding to strain hole and levels induced by structure or seismic loads.

downhole Pressuremet X X Consider test as possibly useful but not fully evaluated.

er For soils and soft rocks, shales, etc.

Chamber X X test Uniaxial X X (tunnel) jacking Flatjacking X Borehole X jack or dilatometer Plate X bearing Plate X bearing Standard X Correlation with static or effective shear modulus, in penetration psi, of sands; settlement of footings on clay. Static shear modulus of sand is approximately: G., =

1960N°' in psi; N is SPT value.

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APPENDIX G Instruments for Measuring Groundwater Pressure (Reproduced from NUREG/CR-5738)

Instrument Type Advantages Limitationsa Observation well Can be installed by drillers without participation of Provides undesirable vertical connection between geotechnical personnel. strata and is therefore often misleading; should rarely be used.

Open standpipe piezometer Reliable. Long successful performance record. Long time lag. Subject to damage by construction Self-de-airing if inside diameter of standpipe is equipment and by vertical compression of soil adequate. Integrity of seal can be checked around standpipe. Extension of standpipe through after installation. Can be converted to embankment fill interrupts construction and causes diaphragm piezometer. Can be used for inferior compaction. Porous filter can plug owing to sampling groundwater. Can be used to repeated water inflow and outflow. Push-in versions measure permeability. subject to several potential errors.

Twin-tube hydraulic piezometer Inaccessible components have no moving Application generally limited to long-term monitoring parts. Reliable. Long successful performance of pore water pressure in embankment dams.

record. When installed in fill, integrity can be Elaborate terminal arrangements needed. Tubing checked after installation. Piezometer cavity must not be significantly above minimum piezometric can be flushed. Can be used to measure elevation. Periodic flushing may be required.

permeability. Attention to many details is necessary.

(0 Pneumatic piezometer Short time lag. Calibrated part of system Attention must be paid to many details when making accessible. Minimum interference to selection. Push-in versions subject to several construction: level of tubes and readout potential errors.

independent of level of tip. No freezing problems.

Vibrating wire piezometer Easy to read. Short time lag. Minimum Special manufacturing techniques required to interference to construction: level of lead wires minimize zero drift. Need for lightning protection and readout independent of level of tip. Lead should be evaluated. Push-in version subject to wire effects minimal. Can be used to read several potential errors.

negative pore water pressures. No freezing problems.

Unbonded electrical resistance piezometer Easy to read. Short time lag. Minimum Low electrical output. Lead wire effects.

interference to construction: level of lead wires Errors caused by moisture and electrical and readout independent of level of tip. Can be connections are possible. Need for lightning used to read negative pore water pressures. protection should be evaluated.

No freezing problems. Provides temperature measurement. Some types suitable for dynamic measurements.

APPENDIX G, Cont'd.

Instrument Type Advantages Limitationsa Bonded electrical resistance piezometer Easy to read. Short time lag. Minimum Low electrical output. Lead wire effects.

interference to construction: level of lead wires Errors caused by moisture, temperature, and and readout independent of level of tip. Suitable electrical connections are possible. Long-term for dynamic measurements. Can be used to stability uncertain. Need for lightning protection read negative pore water pressures. No freezing should be evaluated. Push-in version subject problems, to several potential errors.

Multipoint piezometer, with packers Provides detailed pressure-depth measurements. Limited number of measurement points.

Can be installed in horizontal or upward boreholes. Other limitations depend on type of Other advantages depend on type of piezometer: piezometer: see above in table.

see above in table.

Multipoint piezometer, surrounded with grout Provides detailed pressure-depth measurements. Limited number of measurement points.

Simple installation procedure. Other advantages Applicable only in uniform clay of known depend on type of piezometer: see above in properties. Difficult to ensure in-place table. grout of known properties. Other limitations depend on type of piezometer: see above in 0 table.

Multipoint push-in piezometer Provides detailed pressure-depth measurements. Limited number of measurement points.

Simple installation procedure. Other advantages Subject to several potential errors.

depend on type of piezometer: see above in Other limitations depend on type of table. piezometer: see above in table.

Multipoint piezometer, with movable probe Provides detailed pressure-depth measurements. Complex installation procedure.

Unlimited number of measurement points. Periodic manual readings only.

Allows determination of permeability.

Calibrated part of system accessible.

Great depth capability.

Westbay Instruments system can be used for sampling groundwater and can be combined with inclinometer casing.

a Diaphragm piezometer readings indicate the head above the peizometer, and the elevation of the piezometer must be measured or estimated if piezometric elevation is required. All diaphragm piezometers, except those provided with a vent to the atmosphere, are sensitive to barometric pressure changes.

REGULATORY ANALYSIS

1. STATEMENT OF THE PROBLEM Revision 1 of Regulatory Guide 1.132, "Site Investigations for Foundations of Nuclear Power Plants" was issued in March 1979. It describes acceptable methods for complying with the Commission's regulations with respect to determining geological, engineering, and hydrological characteristics of a prospective plant site for the purpose of evaluating safety and design of foundations and earthworks. In the intervening time, both the practice of geotechnical field investigations and the NRC regulations for plant siting have changed.

New regulations were issued: Subpart B, "Evaluation Factors for Stationary Power Reactor Site Applications on or After January 10, 1997," of 10 CFR Part 100. The new regulations have a major impact on seismic siting criteria, which necessitated revising Regulatory Guide 1.165 in March 1997. While the impact on geotechnical site investigations is much smaller, it is still advisable to revise the related guidance in Regulatory Guide 1.132. This is particularly so, because many of the practices in field investigations have changed. Among the notable changes are an increased use of geophysical methods, and the newly developed Global Positioning System (GPS) surveying methods, together with the use of computer-based Geographic Information Systems (GIS). Some of the ASTM standards related to borehole drilling and in situ test procedures have also been changed.

In the staff's view, a revision to Regulatory Guide 1.132 would promote the use of newer and more efficient methods of investigation, providing a better basis for evaluating site safety with respect to foundation design for critical structures.

2. OBJECTIVE The objective of this regulatory action is to update NRC guidance on geotechnical site investigations for the design of foundations and earthworks to conform with new regulations and practices.

3. ALTERNATIVES AND CONSEQUENCES OF THE PROPOSED ACTION 3.1 Alternative 1 (Do not revise Regulatory Guide 1 .132)

Under this alternative, license applications for nuclear power plants submitted after January 10, 1997, would continue to be based on the practices of over 20 years ago, as far as geotechnical site investigations are concerned. Some future applicants may, on their own initiative, use more modern procedures, but would not be required to do so.

This alternative is considered the baseline, or no action, alternative.

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3.2 Alternative 2 (Revise Regulatory Guide 1.132)

Alternative 2 would have the following consequences.

(1) Benefits. Conducting investigations with newer methodologies and specifications is expedient because this represents the present practice in the industry. Other benefits to be derived from the new guidance include better or less costly design and reduced risk from better designed plants.

(2) Costs. Costs would not be expected to change because no new or different types of investigations are specified. Geophysical methods of site exploration have been added; Revision 1 of the guide only mentioned geophysical investigations peripherally, together with borehole geophysical logging. While including geophysical methods could be considered an additional recommendation, it is the present state of practice in that these methods are being used today in virtually any large site investigation of a geological engineering nature. The reason for using geophysical methods is to reduce the costs of the overall investigation, because the only other way to get the same amount of information about the subsurface is to conduct additional drilling and borehole testing, which is the most expensive part of site investigations. Thus, the inclusion of geophysical methods tends to lower the cost of the site investigation.

A second recommendation that has been added is the use of a Geographic Information System in conjunction with surveying via the Global Positioning System. Again, these items have become standard practice because they generally simplify surveying procedures and the recording and displaying of spatial information. This recommendation should, therefore, not increase overall costs.

4. CONCLUSION Based on the regulatory analysis, it is recommended that a revision to Regulatory Guide 1.132 be issued for public comment. This revision of the regulatory guide should be beneficial because it may lead to safer plant designs, whereas the costs of the investigations should decrease or at least not materially increase. The staff sees no adverse effects associated with the revision.

BACKFIT ANALYSIS The regulatory guide does not require a backfit analysis as described in 10 CFR 50.109(c) because it does not impose a new or amended provision in the NRC's rules or a regulatory staff position interpreting the NRC's rules that is either new or different from a previous applicable staff position. In addition, this regulatory guide does not require the modification or addition to systems, structures, components, or design of a facility or the procedures or organization required to design, construct, or operate a facility. Rather, a licensee or applicant can select a preferred method for achieving compliance with a 52

license or the rules or the orders of the Commission as described in 10 CFR 50.109(a)(7).

This regulatory guide provides an opportunity to use industry-developed standards, if that is a licensee's or applicant's preferred method.

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