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Canteen Facility November 20, 2000 <br /> Quarterly Groundwater Monitoring Report Page 4 <br /> µg/L Only the groundwater sample from MW-13 exceeded the CAMCL for <br /> xylenes <br /> • TPH(g) was detected in monitor wells MW-3, MW-3A, MW-313, MW-13 and <br /> MW-13A at concentrations ranging from 78 to 220,000 µg/l <br /> • Of the oxygenates analyzed, only Methyl-t-Butyl Ether (MTBE), was detected in <br /> MW-3A and MW-13 at concentrations ranging from 110 µg/1 to 720 µg/l The <br /> CAMCL for MTBE is 13 µg/l The concentrations reported for MW-3A and <br /> MW-13 have increased MW-3 was reported at 2 9 µg/1 in June 1999, but the <br /> September 2000 sampling event did not detect MTBE in MW-3 <br /> Groundwater analytical data are summarized on Table 2 <br /> INVESTIGATION SUMMARY and CONCLUSIONS <br /> Sampling and analysis was performed in March 2000 to evaluate the current concentrations of <br /> petroleum hydrocarbons of on-Site groundwater Based on the results, AES has developed the <br /> following conclusions <br /> • Monitor wells MW-3, MW-3A, MW-313, MW-10, MW-13 and MW-13A had <br /> detectable concentrations that exceeded the target cleanup criteria of at least one of <br /> the following constituents benzene, toluene, ethylbenzene, xylenes and MTBE <br /> • Groundwater impacts appear to be confined onsite, since offsite monitor wells MW-8 <br /> and MW-9 do not have detectable BTEX constituents The majority of the <br /> groundwater impacts are centered on the MW-3 and MW-13 series wells <br /> RECOMMENDATIONS <br /> AES recommends the following for the Canteen Facility <br /> • Continue quarterly groundwater monitoring and reporting, to include measurement of <br /> depth to groundwater in each well, monitor well status, preparation of a <br /> potentiometric surface contour map, calculated gradient, and approximate rate of <br /> groundwater movement Groundwater samples will be analyzed for BTEX, TPH(g), <br /> and the five oxygenates (Tertiary Butyl Alcohol [TBA], Methyl Tertiary Butyl Ether <br /> [MTBE], Di-isopropyl ether [DIPE], Ethyl Tertiary Butyl Ether [ETBE], and Tertiary <br /> Amyl Methyl Ether [TAME]) by EPA methods 8020, 8015 modified, and 8260B, <br /> respectively <br />