SITE INFORMATION AND CORRESPONDENCE

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i monitor well be installed on the site northeast of the I1formerr tank area to evaluate the i possibledowngradient migration of hydrocarbons in groundwater. Monitor well MW-4 was installed at the site during July 1992 in accordance with the EHD-approved WESTON work plan. All analytical results for groundwater samples collected from monitor wells at the site indicate non-detect for totaltroleum hydrocarbons as asoline H- Pe y G and benzene toluene ethylbenzene and xylenes (BTEX) compounds. A complete'!summary of groundwater analytical results are presented in Table 2. ,i 4.0 1"4S-oU And QrmndwaterIn i i n In November 1993, the EHD issued a letter requiring an additional investigation to determine the horizontal and the vertical extent of soil contamination and to evaluate the extent of contaminants in groundwater. WESTON conducted a field investigation from July 5 through 7 r 1994. Twelve soil samples were collected from four soil borings and were submitted 'for analysis of TPH-G and BTEX. Two groundwater samples were collected using a bailer and Hydropunch®groundwater sampling 11 tool, at soil borings SB-3 and SB-4 (see Figure 1). The groundwater samples were also analyzed for TPH-G and BTEX compounds. The results of the soil and groundwater analyses are summarized in Tables 1 and 2. j� TPH-G was detected in only two soil samples, one from SB-1 and the other from SB-2. The n co ceritration detected in B-1 S at 50 feet below round surface s was 0.014 mg/kg. The 20 g rog ) feet bgs sample from SB-2 was analyzed twice because the' surrogate recovery from the initial analyses was high due to background matrix interference and the se'cond analysis was completed eted one day past holding time. The initial result 6,000 m /kg�, is most likely biased high, based on high surrogate recovery, and the second result, 210 mg/kg is not reliable because the holding time was exceeded. However, it can be concluded that the 20 foot sample from SB-2 contained TPH-G at concentrations between 210 mg/kg and 6000 mg%kg. I� BTEX compounds were detected in the 50 foot soil sample from SB-2 at concentrations ranging from 0.0024 mg/kg to 0.0098 mg/kg, and results for the 20 foot soil sample indicate the presence of Xylene at 8.5 mg/kg (see Table 1). TPH-G and BTEX were not detected in either groundwater samples collected from soil borings SB-3 or SB4. } �r 5.0 SiJMMARY_ " Soil and groundwater samples have been collected from this site beginning in August 1986 in support of underground storage tank removals, quarterly,'I sampling events, and a soil and ii 5