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June 30, 1995 <br /> Page 5 <br /> appears to be minimal. This interpretation may explain the absence of <br /> a significant hydrocarbon impact to soils and is supported by the low <br /> concentration of hydrocarbons detected in groundwater. Soil investi- <br /> gations that have been performed at the site include seven soil borings <br /> (these borings were converted to Wells MW-1 through MW-7), seven <br /> soil samples (collected from beneath the former USTs), and seven soil <br /> vapor probes (VP-I through VP-7). Hydrocarbons were not detected <br /> during the fourth quarter 1994 in groundwater samples collected from <br /> Wells MW-3, MW-5, MW-6, or MW-7. Total petroleum <br /> hydrocarbons calculated as gasoline (TPH-g) were detected in <br /> groundwater samples collected from Wells MW-2 and MW-4 during <br /> the fourth quarter 1994 at concentrations of 2,900 and 630 parts per <br /> billion (ppb), respectively. These concentrations, however, may <br /> include, appear to include contributions from the chlorinated plume. <br /> Specifically addressing the PHS\EPD comment regarding subsurface <br /> investigation adjacent to the former piping at the site, several wells and <br /> a soil vapor probe have been installed in proximity to the former piping <br /> (Wells MW-I and MW-6 and vapor probe VP-6). Data from these <br /> investigations including soil and groundwater analytical data do not <br /> suggest that the former piping is a significant primary source. To <br /> confirm this interpretation, three soil borings have been proposed at <br /> locations shown on Figure 4 of the CAP revision. <br /> 2. The (:AP does not provide data that shows that the product delivery <br /> system is no longer contributing to the contamination of the site. <br /> The USTs spill containment fill buckets were identified to require <br /> repair in 1993. The spill containment fill buckets were subsequently <br /> replaced in December, 1993 with updated models. <br /> 2.3 Secondary Source <br /> I. The residual soil contamination is a secondary source; not acknowl- <br /> edged in CAP. <br /> Secondary sources of residual petroleum hydrocarbons beneath the site <br /> were identified as: groundwater and potential capillary fringe impact <br /> with weathered dissolved hydrocarbons. Although not addressed by <br /> this CAP, it should be noted that chlorinated compounds have been <br /> 320135700 AP LET.DOC.doc <br />