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6 <br /> DISCUSSION AND RESULTS <br /> •, Fuel Hydrocarbons in Soil <br /> The analytical results of the soil samples indicated detectable concentrations of <br /> TPHg and BTEX constituents in all soil samples collected from all four monitoring wells <br /> at depths ranging from 15 to 25 feet below grade The highest TPHg concentration was <br /> detected at 20 feet below grade in MW-2 (28100 mg/kg) The lowest concentration was <br /> detected at 20 feet below grade in MW4 (3 mg/kg) The highest Benzene concentration <br /> was detected at 20 feet below grade in MW-2 (183,000 Ug/Kg) The lowest concentration <br /> was detected at 20 feet below grade in MW-4 (128 Ug/Kg) The estimated lateral and <br /> vertical extent of fuel hydrocarbons in unsaturated soil are shown in Figures 4,6,and 7. <br /> Fuel Hydrocarbons in Groundwater <br /> The analytical results of the groundwater samples collected from wells MW-I <br /> through MW4 indicated detectable concentration of TPHg and Benzene constituents in <br /> all groundwater samples collected from all four monitoring wells The highest TPHg <br /> concentration was detected at MWA (65900 ug/L ) The lowest concentration was <br /> detected at MW-3 (17800 ug/L) The highest BTEX concentration was detected at MW- <br /> 1 and lowest concentration was indicated at MW-3 The estimated lateral and vertical <br /> extent of the Fuel Hydrocarbons in groundwater are shown in Figures 5,6 and 7.The <br /> analytical results of the groundwater sample collected from the domestic well on the site <br /> was non-detected <br /> CONCLUSIONS AND RECOMMENDATIONS <br /> . From the data collected dunng this phase of the investigation, Arrowhead <br /> Consultants, Inc concludes that a significant release of hydrocarbons occurred and has <br /> impacted both the soil and groundwater beneath the site <br /> Arrowhead Consulting recommends that further assessment work be performed to <br /> adequately characterize the extent of the release Further investigation is required by <br /> drilling additional soil borings and installing a downgradient monitoring well We also <br /> recommend that the nearby domestic wells be sampled for analysis We recommend that <br /> groundwater quality be monitored quarterly for TPHg, BTEX, and MTBE <br />