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.r <br /> CLEARWATER <br /> G R O U P, I N C <br /> Enviranmenta! Services <br /> portion of the site and assess possible off-site sources A total of three soil samples and one groundwater <br /> sample were analyzed from each boring Soil concentrations of TPHg and BTEX were only detected in <br /> boring MW-5B The highest soil concentration of TPHg (1,000 mg/kg) was detected at 25 feet bgs in <br /> MW-513 This sample was also analyzed for TPH as Jet Fuel and contained 55 mg/kg Detectable <br /> concentrations of BTEX were present in soil samples collected from boring MW-5B at 25 feet and 35 feet <br /> bgs MTBE was not detected by EPA method 8260 in any of the soil samples analyzed Groundwater <br /> concentrations of TPHg and BTEX were detected in borings SB-9, MW-5B, MW-7 and MW-8 The <br /> highest groundwater concentration of TPHg (9,700 gg/L) was detected in MW-5B MTBE was not <br /> detected by EPA method 8260 in any of the groundwater samples analyzed <br /> GROUNDWATER MONITORING AND SAMPLING ACTIVITIES <br /> Date of groundwater sampling June 6,2000 <br /> Wells gauged MW-1 through MW-8 <br /> Wells purged and sampled MW-1 through MW-8 <br /> Analytes tested TPHg/BTEX/MTBE (EPA Method 8015M/8020) <br /> Laboratory Entech Analytical Labs, (Sunnyvale, CA) <br /> Remarks None <br /> GROUNDWATER MONITORING AND SAMPLING RESULTS <br /> Depth to groundwater 7 34 to 10 42 feet below top of casing <br /> Flow direction Southeast at 0 0062 ft/ft <br /> TI'Hg concentration range < 50 gg/L (MW-2,MW-4) to 13,000 µg/L (NIW-5B) <br /> Benzene concentration range <0 50 gg/L (MW-2, MW-3, MW-4) to 1,700 ug/L (MW-5B) <br /> MTBE concentration range <5 0µg/L(MW-1 through MW-4, MW-7,MW-8) to 72 µg/L <br /> (MW-5B) <br /> Remarks MTBE was detected by EPA 8020 in groundwater samples collected this quarter Previously <br /> MTBE has been confirmed as "non-detectable"by EPA 8260 in all monitoring wells sampled at the site <br /> PROJECT STATUS&RECOMMENDATIONS <br /> The contaminant plume is currently delineated and being monitored cn a quarterly basis Clearwater <br /> recommends quarterly sampling for four quarters to examine trends in hydrocarbon concentrations and <br /> distribution If hydrocarbon concentrations exhibit a downward trends in concentrations within the core <br /> of the plume, then Clearwater will recommend collecting data to document rernediation by natural <br /> attenuation If concentrations do not fall, then Clearwater will evaluate other options for the reduction <br /> of contaminant concentrations <br /> CGI-ZB178C-2QT00 3 June 20,2000 <br />