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C u FICEIVED <br /> Work Plan For Plume Evaluation APR 2 1 2000 <br /> Quik Stop Market No. 132 <br /> 3555 West Hammer Lane JNViROivMENTAL HEALTH <br /> Stockton, California PERMIT/SERVICES <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. TPHg;was present in the groundwater sample obtained from MW-1[320 <br /> micrograms per liter (ug/L)]. BTEX (at least one constituent) was present in the 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-1. The locations of soil <br /> borings and groundwater monitoring wells are shown on Figure 2. <br /> Review of the site geology indicates that two separate groundwater 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 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-1 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-IA and MW-5). The soil and groundwater <br /> samples (from new and existing groundwater monitoring wells) were analyzed for TPHg and <br /> BTEX in accordance with EPA test methods 8015 and 8020, respectively. TPHg and BTEX <br /> were not present in any of the soil borings. TPHg was present in the groundwater sample <br /> obtained from MW-5 (210 ug/L).. Benzene (3.4.ug/L) and xylenes (2.1 ug/L) were present in the <br /> groundwater sample obtained from groundwater monitoring well MW-5. The locations of <br /> groundwater monitoring wells are shown on Figure 2. <br /> On April 29, 1992, RESNA Industries Inc. (RESNA) completed a Shallow Soil Gas and <br /> Groundwater Survey around the Taco Bell property adjacent to the site. Tracer Research <br /> Corporation of Tucson, Arizona was subcontracted to perform the survey. -A '/4 inch diameter <br /> probe was advanced to depths as deep as 20 feet bgs at ten locations along the south and east <br /> ry sides of the Taco Bell property. A total of seven soil gas and six groundwater samples were <br /> �1 collected from the holes. Very low concentrations of petroleum hydrocarbons were detected in <br /> three soil gas samples and two groundwater samples. Based on resistance during advancement, it <br /> was concluded that at depths of 8 to 14 feet bgs, a dense less porous soil is present. <br /> On December 9, 1992, RESNA completed an additional site assessment consisting of the <br /> installation of two additional off-site groundwater monitoring wells (MW-6 and MW-7). The soil <br /> and groundwater samples (from new and existing groundwater monitoring wells) were analyzed <br /> for TPHg and BTEX in accordance with EPA test methods 8015 and 8020, respectively. TPHg <br /> n and BTEX were not present in any of the soil borings. TPHg was present in a groundwater <br /> E! sample obtained from MW-5 (350 ug/L). BTEX (at least one constituent) was present in <br /> groundwater samples obtained from MW-2 and MW-5. The maximum benzene concentration <br /> n was 0.66 ug/L in the groundwater sample obtained from groundwater monitoring well MW-2. <br /> E� The locations of groundwater monitoring wells are shown on Figure 2. <br /> L <br /> t1 1:Un Nope \QUIKS'MPtQS I31(0003)\REPORT11"MORKPLAN(X-sects A Tank Ie W)Aoa <br /> 2 <br />