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`�Lrk Plan for Additional Groundwater Invest ion <br /> Quik Stop Market No. 132 <br /> 3555 West Hammer Lane <br /> Stockton,California <br /> n <br /> 5. 'r.BTEX (at least one constituent) were present in at least one soil sample obtained from B-1, 13- <br /> 2, B-3, B-5 and MW-1. The maximum TPH-G concentration was 460 milligrams per kilograms <br /> (mg/kg) in the soil sample obtained from B-3 at a depth of 15 feet below ground surface (bgs): <br /> The maximum benzene concentration was 3.9 mg/kg in the soil sample obtained from B-3 at a <br /> depth of 15 feet bgs. TPH-G was present in the groundwater sample obtained from MW-1 [320 <br /> micrograms per liter (ug/L)]. BTEX (at least one constituent) were present inithe groundwater <br /> samples obtained from MW-1 and MW-2. The maximum benzene concentration was 34 ug/L in <br /> the groundwater sample obtained from groundwater monitoring well MW-l. <br /> Review of the site geology indicates that two separate groi undwater bearing;zones may exist <br /> beneath the site. The upper groundwater bearing zone appears to be present from approximately <br /> 14 to 19 feet bgs, and the lower groundwater bearing I zone appears to be present from <br /> approximately 20 to 30 feet bgs. Consequently, on October 3, 1990, Exceltech abandoned <br /> groundwater monitoring well MW-I due to the concern that this groundwater''monitoring well <br /> could possibly connect the two groundwater bearing zones. <br /> On-April 2, 1991, Exceltech completed an additional site assessment consisting of the installation <br /> of`two additional groundwater monitoring wells (MW?lA and MW-5).: ; The soil and f <br /> groundwater samples (from new and existing groundwater monitoring wells) were analyzed for ` <br /> TPH-G and BTEX in accordance with EPA Test Methods 8015 and 8020, respectively. TPH-G <br /> and BTEX were not present in any of the soil borings. TPH-G was present in the groundwater <br /> sample obtained from MW-5 (210 ug/L). Benzene (3.4 ug/L) and xylenes i(2.1 ug/L) were <br /> present in groundwater sample obtained from groundwater monitoring well MW-5. <br /> Ori December 9, 1992, RESNA Industries Inc. (RESNA) completed an additional site assessment <br /> consisting of the installation of two additional off-site groundwater monitoring wells (MW-6 and <br /> MW-7). The soil and groundwater samples (from new and existing groundwater monitoring <br /> wells) were analyzed for TPH-G and BTEX in accordance with EPA Test Methods 8015 and <br /> 8020, respectively. TPH-G and BTEX were not present in any of the soil borings. TPH-G was <br /> present in groundwater sample obtained from MW-5 (350 ug/L). BTEX (at least one <br /> constituent) were present in groundwater samples obtained from MW-2 and MW-5. The <br /> maximum benzene concentration was 0.66 ug/L in the groundwater sample obtained from <br /> groundwater monitoring well MW-2. <br /> In March 1996, groundwater samples obtained from groundwater monitoring wells MW-1R, j <br /> MW-2, MW-5, MW-6 and MW-7 were first analyzed forjmethyl tert-butyl ether (MTBE) in <br /> accordance with EPA Test Method 8020. MTBE was present in groundwater samples obtained <br /> from MW-1R, MW-2 and MW-5. The maximum MTBE concentration was present in <br /> groundwater sample obtained from MW-5 (1,100 ug/L).'! MTBE concentrations in MW-5 <br /> subsequently decreased steadily for five quarters until September 1997 when the MTBE <br /> concentrations rose back to 1,100 ug/L. <br /> \\P[..Wn\admi.MkW.inez\QuikSmp\Quik I32W.ftI nOfr-sitc.duc 2 <br /> II 1 <br />