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• <br /> Analysis of the groundwater samples indicated that the extent of dissolved-phase <br /> contamination remained undelineated downgradient from the former UST system <br /> However, high contaminant concentrations in cross-gradient positioned wells suggested <br /> that off-site sources could be contributing to contamination detected beneath the site <br /> Inquiries suggested and later confirmed the existence of a fuel transport lane in the area of <br /> the site The line was found to be filled with nitrogen gas Based on this information, <br /> Clearwater recommended additional investigation along South Fresno Avenue to better <br /> understand the distribution of contamination and possible contribution from potential off- <br /> site sources The results of this phase of investigation were presented in Clearwater's <br /> Well Installation and Groundwater Monitoring Report -First Quarter 1999 <br /> 2000 <br /> In March 2000, Clearwater supervised the completion of one hydropunch, six soil <br /> borings, the destruction of MW-5, and the installation of three additional monitoring <br /> wells (MW-5B, MW-7, and MW-8) in three of the soil borings All three wells were <br /> placed on the downgradient portion of the plume to help determine the downgradient <br /> extent of contaminants The hydropunch was performed in the former UST location to <br /> assess the vertical extent of groundwater contamination at 36 feet bgs Three soil borings <br /> were taken to define the lateral extent of soil and groundwater contamination on the <br /> northeastern portion of the site and assess possible off-site sources Three soil samples <br /> and one groundwater sample were analyzed from each boring Soil concentrations of <br /> TPHg and BTEX were detected only in boring MW-5B The highest soil concentration <br /> of TPHg (1,000 mg/kg) was detected at 25 feet bgs in MW-5B This sample was also <br /> analyzed for TPH as Jet Fuel (TPHjf) and found to contain 55 mg/kg TPHjf is unlikely <br /> to be present, but is an indicator of a hydrocarbon range on a chromatographic pattern, <br /> not a specific product Detectable concentrations of BTEX were present in soil samples <br /> collected from boring MW-5B at 25 feet and 35 feet bgs MTBE was not detected by <br /> EPA method 8260 in any of the soil samples analyzed Groundwater concentrations of <br /> TPHg and BTEX were detected in borings SB-9, MW-5B, MW-7 and MW-8 The <br />