Table 4 lists these and other suggested methods for laboratory analysis of soil,

unconsolidated materials, and rock samples. Laboratory methods for determining the

properties of subsurface samples are provided by ASTM, and by both the American Society

of Agronomy and the Soil Science Society of America.

4.2.3

Mapping Programs

Subsequent to the generation and interpretation of site specific geologic data, the data

should be presented in geologic cross sections, topographic maps, geologic maps, and soil

maps. The Agency suggests that owners/operators obtain or prepare and review topographic,

geologic, and soil maps of the facility, in addition to site maps of the facility and waste

management units. In cases where suitable maps are not available, or where the information

contained on available maps is not complete or accurate, detailed mapping of the site should

be performed by qualified and experienced individuals.

Although topographic coverage of the entire United States is available through the

U.S. Geological Survey (USGS), owners and operators may find that detailed or smaller scale

topographic information is not directly available for their facility. Many facilities have been

successful in preparing topographic maps, or altering or updating existing topographic maps

(such as those obtained from local government offices), to include the level of detail

appropriate for a site specific hydrogeologic investigation. Often this includes adding

information such as the locations of small or intermittent streams, wetlands, topographic

depressions, and springs, or adding additional contours (i.e., decreasing the contour interval of

the map to 2 or 5 feet) to existing maps. Developing a topographic map for the facility will

generally require employing a conventional or photogrammetric survey company that develops

topographic maps by obtaining data aerially. This information may be supplemented with

information obtained from stereoscopic aerial photographs (Waste Management, Inc., 1989).

Wetlands information may be obtained from National Wetlands Inventory Maps which was

developed by the National Fish and Wildlife Service. This information is available through

the USGS.

The USGS has prepared geologic maps at the 1:24,000 scale (7.5 minute quadrangle)

for less than 10% of the United States. Consequently, it is likely that geology will not have

been mapped at most facilities. Moreover, geologic mapping is generally not as easy to

perform as topographic mapping, and the information provided on a geologic map obtained

from the USGS may not be as detailed as topographic information. While mapping of

outcrops is impossible in areas where geologic strata are not exposed at the surface, detailed

mapping of exposed strata at and in the vicinity of the facility may provide necessary

information on the local stratigraphic and structural setting. Field (1987) provides a detailed

discussion of a RCRA site that required extensive geologic analysis by EPA Region II for a

ground water monitoring waiver determination. Table 5 lists the information that should be

recorded during a mapping program. In general, for mapping of outcrops, the following

information should be provided:

November 1992

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