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1 <br /> GRANITE CONSTRUCTION <br /> WKA No 2088 07 <br /> April 7, 1995 <br /> Page 5 <br />' Based on the laboratory analysis of water samples and a northeast ground water flow direction, <br /> we recommended the installation of three additional wells down-gradient from the USTs to help <br />' delineate the lateral extent of contamination In addition, we recommended that the contaminated <br /> soil in the area of the former dispenser island be excavated, stockpiled on-site, and characterized <br /> for subsequent treatment and/or disposal A more detailed discussion of our soil and ground <br /> water investigation can be found in our April 29, 1993 Report of Findings on file with EHD <br />' Based on the findings of the above soil and ground water investigation, a Workplan dated July <br /> 26, 1993 was prepared to investigate the lateral extent of ground water contamination and to <br /> excavate the diesel contaminated soil in the vicinity of the former dispenser island <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 /> Analytical results of soil samples obtained during the construction of monitoring wells MW4 <br /> 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 /> revealed no detectable concentrations of TPH as gasoline, diesel, or BTEX However, water <br /> samples collected from MW1 through MW3 revealed detectable concentrations of TPH as <br /> gasoline ranging from 590 µg/P to 3,200 µglf, BTEX constituents were also detected <br />' On September 28, 1993, approximately 700 cubic yards of diesel contaminated soil were <br /> excavated from the vicinity of the former dispenser island Thirteen soil samples were obtained <br /> I from the bottom and sidewalls of the excavation Analytical results of the excavation soil <br /> samples generally revealed low but detectable concentrations of TPH as diesel Based on the <br /> analytical results of the excavation samples, it was our opinion that additional excavation beneath <br /> Ithe former dispenser location was not necessary and recommended backfilling the excavation <br /> The excavation was backfilled by Granite Construction Company using clean fill, following <br /> authorization from EHD The soil removed from the excavation has been sampled and is <br /> currently stockpiled at the location shown on Plate 2 <br /> WALLACE-KUHL <br /> Recyded paper 6A5 'OCIATES INC <br />