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Parsons Engineering Science, Inc <br /> SUMMARY, CONCLUSIONS AND RECOMMENDATIONS <br /> Introduction <br /> The summary and conclusions presented in this section are based on field work, data <br /> collected and interpretations developed in this report The summary and conclusions are <br /> presented in sections on 1) site stratigraphy and hydrogeology, 2) soil chemistry, and <br /> 3) groundwater chemistry <br /> Summary and Conclusions <br /> Site raPY and d H drogeology <br /> Y <br /> • The subsurface environment is heterogeneous and anisotropic The predominant <br /> materials encountered are silts and clays with minor layers/lenses of silty/clayey <br /> sands In general, these materials prohibit the migration of contaminants through the <br /> subsurface <br /> • Over the past five years, the depth to groundwater has fluctuated from between <br /> approximately 28 and 45 feet bgs The groundwater elevation has steadily risen over <br /> the past five years as climatic conditions have changed from dry to wet <br /> oWater level measurements bgenerally indicate that the horizontal groundwater flow <br /> direction beneath the site is southwest <br /> Soil Chemistry <br /> • TPH-D and BTEX compounds have been detected in subsurface soils underlying the <br /> site TPH-G was not detected in six soil samples <br /> • The highest concentrations of TPH-D (greater than 100 mg/kg) have been detected at <br /> depths of 15 and 30 feet bgs However, the areas with high TPH-D concentrations <br /> appear to be of limited to the immediate vicinity of the former UFST pit <br /> • The highest concentrations of BTEX compounds are associated with the highest <br /> concentrations of TPH-D The distribution of these compounds appears to also be <br /> limited in extent Benzene was not detected at concentrations in excess of 50 Pg/kg <br /> r • AnalyticaI results from soil samples collected in boring SB-9 indicate that <br /> contaminated soil does not extent beyond the west side of the site A total of 10 soil <br /> samples were collected during advancement of this soil boring TPH-D and BTEX <br /> were not detected in any of these soil samples <br /> 4 <br /> PARSSSYR01 VOLIR%WP1727607 80969127607R03 WW6 12 <br />