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30111 0I' -----.- _. monitor well be installed on the silt norffi" of the IDTmer tank arra to c aluate the possibledowngradi mt migration of hydrocarbons in groundwater. Monitor well MW-4 was installed at the site during July 1992 in acaordanoe with the -approved WESTON work plan. All atWyff *l results for gnaundwater samples collected from monitor wells at the site indicsau non4dect for total petroleum hydrocarbons as gasoline (TPH-G) and benzrne, toluene, ethylbenzene and xylenes(BTEX)compounds. A complete summary of groundwater andyfical resWts are pnesentcd in Table 2. 4.0 19914 Solt And Q=dsrater b, iestion In Nmmber 1993, the EHD issued a letter requiring an additional investigation to deu nine the horizontal and the vertical extent of soil contamination and to avaluate the extent of contaminants in groundwater. WESTON conducted a field investigation from July S through 7, 1994. Twelve sail samples were oWllected from four soil borings and were submitted for analysis of TPH-G and BTEK. Theo groundwater samples were collected using a bailer and Hydropunch"groundwater&mpling tool,at soil borings SB-3 and SB-4(see Figure 1). The grou ndwalu samples wow also analyzed for TPH-G and BTHX cannpormds. The results of die soil and groundwater analyses are summarized in Tables 1 and 2. TPH-G was demewd in only two soil samples, one from SB-1 and the other ftarn SB-2. The concentration detected in SB-1 at SO feed below ground wrthm(bgs)was 0.014 mg&& The 20 feet bgs sample fmm 5B-2 was analyzed twice because the surrogate; rewvwy from the initW analyses was high due to background matrix inteffiemnm and the=and analysis was completed oae day past holding time. The initial result, 6,000 mglkg, is moat likcly biased high, based on high sumogate remvery, and the=wW result,210 mg/kg is not reliable because the holding time was exceeded. However, it can be conc tkM that the 20 fast sample from S&2 contained TPH-G at conceaftafim between 210 mg ft and 6000 mglltg. BTIX compounds were deed sun the 50 foot soil sample from SB-2 at concentrations ranging from 0.0024 nkglkg to 0.0098 rng ft, and results for the 20 foot roil sample ideate. the presence of Xylene at $.S mgllrg (see Table 1). TPH-G and BTEX were not defected in either groundwater samples collected from soil borings SB-3 or SBS. 3.0 S MMAM Soil and groundwater samples have been collected from this site beginning in August 1986 in suppW of emdergmund storage tank removals, quarterly sampling events, and a soil and 5