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y <br /> 5 <br /> M'• <br /> 98-1 M-IL <br /> 99 4.0 DISCUSSION AND CONCLUSIONS <br /> The results of laboratory analyses of soil and <br /> groundwater samples indicate that the soil and groundwater <br /> are contaminated by petroleum hydrocarbons, concentrations <br /> detected are considered unacceptable by State and local <br /> regulatory agencies. Analysis of soil samples showed low to <br /> moderate detectable concentrations of TPHg and BTEX. <br /> Analyses of the groundwater sample indicate that <br /> concentrations of TPHg and BTEX were very high (200 ppm <br /> { <br /> TPHg, 31 ppm benzene, 11 ppm toluene, 1.9 ppm ethylbenzene, <br /> and 5.2 ppm xylene isomers) . <br /> s? Acceptable ("Action,") levF' - for BTEX in drinking water <br /> f <br /> are 0.001 ppm benzene, 0.1 ppm toluene, 0. 62 ppm <br /> [ ; ethylbenzene, and 0. 68 ppm total xylene isomers. No <br /> I : <br /> standard exists for TPHg at this time. <br /> Because soil and groundwater are contaminated, <br /> additional work will be required to evaluate the degree of <br /> contamination and to define the vertical and lateral extent <br /> responsible <br /> of contaminant migr7tion. Once delineated, the res p <br /> parties can define and implement appropriate measures to <br /> mitigate contamination. A minimum of three additional <br /> monitoring wells will be required to evaluate the <br /> j .; groundwater flow direction and the limits of contamination. <br /> It .is also likely that it will be necessary to drill borings <br /> or install wells on adjoining propertie or in the City of <br /> � a <br /> Stockton right-of-«ay. State guidelines require that a <br /> "Preliminary Assessment Report" be prepared which should <br /> include: <br /> s <br /> Ew Name and address of site, tank owner, and contact <br /> person. <br /> A-map-showing the site relative to nearby landmarks j <br /> (see Site Location Map, Plate 1) , <br /> ROGER FOOTT ASSOCIATES, INC. <br /> �6^ <br /> r.tl <br />