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Groundwater Investigation and Associated Source
Characterization Appendix F - Technical Memorandum on Soil Gas Surveys
Section 2 - SWMU B-2
SWMU B-2 is located in the north pasture north of well 16. Two trenches were observed at this site on aerial photographs and confirmed during this field investigation. Soil mounds are present on the ends of the two trenches (Figure 2.1) These trenches were apparently used for burning small arms ammunition in 1954. Munition canister lids (57mm guns), an unidentified munition, and bricks were also observed. The site is relatively flat and unobstructed except for an occasional small tree or brush and dense overgrowth in the two trenches, which were cleared prior to this investigation. In addition, isolated surface metal was removed from this site and placed outside the area of investigation to reduce interference during the survey. B-2 is bounded by a dirt road to the north and trees to the east, south and west, as well as the fence line between B-1 and B-2.
PCE was the only target compound detected in soil gas samples from B-2. A complete listing of the soil gas survey data is given in Table 2.1. Depth profiles were attempted at several locations, but refusal was typically at 3 feet. Selection of sampling locations was based on the location of geophysical anomalies and the location of the trenches.
Only one minor PCE anomaly, less than 1 ug/L, was present at B-2 (Figure 2.1). The highest concentration detected was 0.32 ug/L and occurred at location M,70 which is located in the middle of the northern trench. Only one week anomalous location was detected suggesting that this site is not a likely source of solvent contamination. Consequently, it was determined that no additional soil gas sampling would be performed at this site during the second phase of the soil gas investigation.