ARCHIVED REPORTS_XR0007518 - Laserfiche WebLink

Home Browse Search

I ' 04 March 2002 AGE-NC Project No 99-0657 ' Page 3 of 4 ' 3 2 ANALYTICAL RESULTS OF GROUND WATER SAMPLES TPH-g and TPH-d was detected in the water samples collected from all the wells at concentrations as high as 33,000 µg/1 and 2,600 µg/1, respectively(MW1) Benzene was detected in all four water samples at concentrations ranging from 47 µg/l in MW3 to 6,900 µg/1 in MW1 Toluene, ethylbenzene and xylenes were detected in the water samples collected from all the wells with the exception of ethylbenzene in MW3, at concentrations as high as 4,600 µg/1 toluene, 390 µg11 ethylbenzene and 2,200 µg11 total xylenes MTBE was detected by EPA Method 8020 in ground water samples collected from wells MW 1, MW2, MW3 and MW4 at concentrations of 13,000 µg/l, 4,100 µg11, 48 µg/1 and 820 µg/1, respectively MTBE was confirmed by EPA Method 8260 in the same samples at concentrations of 18,000 µg11, 5,200 µg/l, 40 µg/1 and 790 µg/1, respectively 1,2-DCA was detected in ground water samples collected from MW3 and MW4 at concentrations as high as 81 µg/l (MW4) EDB and the other fuel additives were not detected in the ground water samples The analytical results of water samples collected in January 2002 are summarized on Table 2 The laboratory report (MAI Lab I D No 88359 through 88362), QA/QC report and chain-of-custody form are included in Appendix B I4.0. SUMMARY AND CONCLUSIONS The following conclusions were drawn from the results of this investigation • The ground water elevations ranged from 7 67 to 7 96 feet above MSL Ground water is inferred to be flowing toward the southwest at an average gradient of 0 004 feet/feet The relative ground water elevation at the site decreased an average 1 06 feet between the October 2001 and January 2002 monitoring events • Concentrations of dissolved TPH-g, TPH-d,BTEX,MTBE and 1,2-DCA have increased in all the wells sampled since the last monitoring event in October 2001 The highest concentration of dissolved hydrocarbons occurred In monitoring wells MW 1 and MW4 which are south and south-southwest and downgradlent of the UST area Isocontour maps depicting the approximate distribution of dissolved MTBE and benzene are presented In Figures 4 and 5 • The lateral and vertical extent ofpetroleum hydrocarbon-Impacted ground water has not been defined • IAdvanced GeoEnvironmental,Inc