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GRANITE CONSTRUCTION FACILITY <br /> WKA No 2088 08 <br /> August 18, 1999 <br /> Page 3 <br /> Subsequent to the UST removals, seventeen soil bonngs (B 1 through B 17) and eight <br /> groundwater monitoring wells (MWI through MW8) were drilled at the site (Plate No 5) Two <br /> soil borings B1 and B2 were drilled at an approximate angle of 30° from the vertical to evaluate <br /> soils beneath the former waste oil UST (Plate No 3) Analysis of soil samples collected from B 1 <br /> and 132 revealed low but detectable concentrations of petroleum hydrocarbons (Table 1) Based <br /> on these findings, the waste oil UST excavation was backfilled with clean fill upon approval <br />' from SJCPHS <br /> Four soil bonngs (B3 through B6) were drilled to depths ranging from of 24 to 29 feet BGS in <br /> the vicinity of the former dispenser island located approximately 80 feet east of the former diesel <br />' and gasoline USTs (Plate No 5) Total petroleum hydrocarbons as gasoline (2,000 mg/kg) and <br /> diesel (7,800 mg/kg) and minor concentrations of benzene, ethylbenzene, and total xylenes were <br /> detected only in sample B4-2I obtained from 6 5 feet BGS <br /> Eleven bonngs (B7 through B 17) were drilled in the vicinity of the former gasoline and diesel <br /> USTs Laboratory analysis of samples obtained from bonngs B7 through B17 revealed <br /> detectable concentrations of TPH as gasoline ranging from 0 70 mg/kg to 930 mg/kg, benzene <br />' ranging from 0 029 mg/kg to 5 3 mg/kg and minor concentrations of toluene ethylbenzene, and <br /> total xylenes at depths ranging from 14 to 26 5 feet BGS <br /> 1 Three monitoring wells (MW1 through MW3) were drilled on March 10 and 11, 1993 and <br /> constructed to depths ranging from 39 to 40 feet below surface grade at the locations shown on <br />' Plate 2 Analysis of the soil samples obtained during the construction of MW1 through MW3 <br /> revealed trace concentrations of TPH as gasoline and benzene in each monitoring well boring <br />' Additionally, TPH as diesel concentrations of 12 mg/kg were revealed in laboratory analysis of <br /> soils obtained from boring MW3 Analytical results of soil samples collected from the soil <br />' bonngs (B 1 through B 17, and MW 1 through MW3) are summarized in Table 2 <br /> On September 22 and 23, 1993, three additional ground water monitoring wells MW4 through <br /> MW6 were constructed northerly and northeasterly of the former gasoline and diesel USTs <br /> (Plate 2) Analytical results of soil samples obtained during the construction of monitoring wells <br /> MW4 through MW6 revealed no detectable concentrations of TPH as gasoline, diesel, or BTEX <br /> Analytical results for water samples obtained from monitoring wells MW4 through MW6 <br /> `aW <br />' WALLACE KUHL <br /> Recy,ied paper &ASSOCIATES INC <br />