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' Well Installation Report 3 7-Eleven Inc. Store#14117 2725 Country Club Boulevard, Stockton,GA August 12, 1999 One grab groundwater sample was also collected from the base of the new underground storage tank ' pit area on July 27, 1998. Benzene and TPH-G were detected at concentrations of 300 pg1L and 3,100 pg/L, respectively. MTBE was detected at a concentration of 27 pg/L. ' Dewatering of the new underground storage tank pit was required prior to setting of the new tanks. A total of 30,900 gallons (approximately) of groundwater was pumped from the new tank pit area prior to ' completion of construction. The groundwater was hauled by a licensed waste hauler to a licensed recycling facility. Three conductor casings are present in the center of the new UST pit, to facilitate groundwater monitoring well installation if needed during subsequent site assessments. The conductor i ' casings are composed of 10-inch diameter solid Schedule 40 PVC piping and extend to approximately 12 feet BGS. Each conductor casing is protected at the surface by 10-diameter slip cap and traffic- rated street box (with watertight bolted lid) set in concrete. On September 9 and October 2, 1998, Fluor Daniel GTI supervised the advancement of six off-site (OSGP-1 through OSGP-6) and eleven on-site (GP-7 through GP-17) geoprobe soil borings (Figure 3) . The off-site soil borings were drilled to a depth of 8 feet with soil samples collected at 4 feet, 6 feet, and 8 feet BGS. The on-site soil borings were drilled to depths ranging from 15 feet to 30 feet BGS. In addition to the soil sampling, grab groundwater samples were collected from each of the borings. Results of the soil sample analysis are summarized in Table land results of the groundwater samples are summarized in Table 2. All soil and groundwater samples collected from the off-site borings did not contain any BTEX, MTBE, or TPH-G concentrations with the exception of the groundwater sample (OSGP-6@W) which contained an MTBE (EPA 8260) concentration of 39 pg/L. In soil samples ' collected from the on-site borings, the highest TPH-G concentration was detected in sample GP-15@15' at 42,900 mg/kg. The highest MTBE (8260) and TBA concentrations were detected in ' sample GP-14@10' at 234 mglkg and 166 mglkg, respectively. The highest benzene concentrations were detected in sample GP-17@20' at 12.5 mg/kg. In the groundwater samples collected from the borings, the highest benzene and TPH-G concentrations were detected in sample GP-17@W at 9,740 ' pg/L and 1,930,000 pg/L, respectively. The highest MTBE concentration (EPA 8260) in groundwater was detected in sample GP-11@W at 24.2 pg/L_ 1 14117,-U rpt