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t <br /> f <br /> 29 August 2001 F <br /> AGE-NC Project No 95-0144 <br /> Page 5 of 7 <br /> Ground water elevations in nested wells MW-1 9, MW-20 and MW-21 were between 143 and 171 <br /> -feet lower in deeper screened intervals beneath a clay layer than in the shallower screened intervals <br /> Data fromwells with the upper screened intervals,established in first-encountered groundwater,was <br /> utilized for gradient determination <br /> _ u <br /> 3 3 ANALYTICAL RESULTS OF WATER SAMPLES H <br /> 1 <br /> During the May 2001 monitoring event, TPH-g was detected in samples from monitoring wells <br /> ' MW-21A and MW-21B at concentrations of 11,000 micrograms per liter (µg11) and 950 µg/1, <br /> respectively BTEX compounds were detected in samples from wells'MW-21A and`MW-21B at <br /> concentrations as high as 150 µg/1 (benzene, MW-21A) TPH-d was detected in samples collected <br /> ' from MW-19A, MW-20A, MW-21A and MW-21B at concentrations of 74 µg%1, 190 µg/1, <br /> 4,900 µg/1 and 630 µg11, respectively TPH-mo was detected in monitoring well sample MW-21A <br /> at a concentration of 1,900 µg/1 The extent of hypdrocarbon-impacted ground water is illustrated <br /> in Figure 4 <br /> MTBE was not detected in ground water samples from the monitoring well network Historically, <br /> only low concentrations of MTBE and TBA have been detected intermittently at the site <br /> Analytical results for May 2001 are summanzed on Table 2 Analytical results of recent and <br /> historical ground water samples are summarized on Table 3 'The laboratory report (MAI Lab IDs <br /> 68101 through 68115) and chain-of-custody forms'are included in Appendix F <br /> a <br /> 3 4 MASS OF REMOVED HYDROCARBONS, <br /> The soil excavated and disposed from the former UST No 1 excavation contained an estimated <br /> 105 pounds (47 6 kg) of petroleum hydrocarbons including TPH-g, TPH-d and,TPH-mo The mass <br /> ' calculation for removed hydrocarbons is mcluded in Appendix G J <br /> ~ <br /> ' 4.0. SUMMARY/CONCLUSIONS , <br /> Based upon data collected during the ground water monitoring event, AGE concludes <br /> 05 t the site since the previous <br /> Ground water elevation increased approximately 0 feet a e p <br /> ' ground water monitoring event Ground water remained above the screened interval in nine, ? <br /> of the shallow wells sampled during the second quarter of 2001 Groundwater elevations in <br /> L <br /> Advanced GeoEavironmentai,Inc <br /> f <br /> n <br />