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ENV <br /> M - ' <br /> M <br /> IT COR20RATION <br /> procedures fcf^ taking soil samples and field hydrocarbon testing are <br /> described in Attachment 1, included with this report. For each boring <br /> r <br /> with a Tower explosive limit (LEL) reading of 10 percent or greater, the <br /> sample with the highest LEL reading was retained in a brass liner, <br /> capped ano refrigerated for laboratory analyses. Soils were classified <br /> in accordance with the Unified Soil Classification System, presented on <br /> Plate 1. Soils and LEL measurements taken during drilling are described <br /> and recorded in the borehole logs on Plates 2 through 11. <br /> 2.2 EARTH MATERIALS <br /> Earth materials encountered during the drilling phases of this investi- <br /> gation are typical of alluvial deposits. The alluvial deposits consist <br /> of interlayered sands (SM, SP, SW) with an occasional lens of clay <br /> r� (CL). As is characteristic of alluvial deposits, the various soil types <br /> are laterally discontinuous, and individual lenses cannot be correlated <br /> between boreholes. Cross-section A-A' (Figure 2.2) shows the distri- <br /> bution of soils along the. section Tine, shown in Figure 2.3. <br /> 2.3 FIELD HYDROCARBON DETECTION <br /> Hydrocarbons were detected in several of the soil samples collected - <br /> using the technique described in Attachment 1. In general, hydrocarbons <br /> were detected in the upper 20 feet in most of the.wells surrounding the <br /> tank pit. Wells MW-1, MW-8, and MW-4, which are the wells most distant <br /> F <br /> from the tank pit, detected hydrocarbons at depths greater than 30 feet. <br /> Field hydrocarbon testing results are shown in Table 2.1. <br /> 2.4 VOLUME OF CONTAMINATED SOIL <br /> A rough estimate of the volume of contaminated soil was made from data <br /> derived from LEL readings at five-fi t increments. The LEL reading,--are <br /> presented in Figures 2.4 through 2.13. If an LEL reading was detected, - <br /> d,, <br /> an assumption was made that the entire five-foot increment was contami- <br /> nated. A simple model of the estimated volume of contaminated soil is <br /> shown in Table 2.2. The model indicates that there is approximately <br />