ARCHIVED REPORTS_XR0007069 - Laserfiche WebLink

Home Browse Search

l 30 May 2005 • AGE-NC Project No 95-0141 Page 4 of 5 4.0. SUMMARY AND CONCLUSIONS The findings of the First Quarter 2005 site investigation include the following • At the time of the March 2005 ground water monitoring event, ground water elevations at the site ranged from 9 94 feet to 1122 feet below MSL The shallow ground water was ' inferred to flow generally towards the southeast, at a gradient of 0 004 ft/ft while the deeper ground water zone was inferred to flow generally toward the northeast, at a gradient of 0 011 ft/ft • TPH-g was detected in ground water samples collected from seven of the sixteen wells at the site at concentrations as high as 150,000 pg/l TPH-g-impacted shallow ground water has been defined (Figure 5) However, the TPH-g-impact to the deeper ground water zone has not been defined toward the east and to a lesser degree south and north (Figure 5) • Various BTEX constituents were detected in nine of the sixteen ground water wells The ' benzene concentrations detected in the wells exceeded the DHS' Maximum Contaminant Level(MCL)for benzene in drinking water The concentrations of toluene,ethylbenzene and • total xylenes were also significantly above their respective MCLS • The increased concentrations of TPH-g and benzene detected in the deep,down-gradient well (MW-8B) may demonstrate a migrating dissolved plume Additionally increased concentrations of TPH-g and benzene detected in the deep, cross-gradient or somewhat up-gradient well (MW-11 B) may indicate a migration of the dissolved plume south of the former UST release area • 1,2-DCA was detected in ground water samples collected from eleven of the sixteen wells at the site at concentrations as high as 190 µg/1 (MW-5) The detected concentrations of ' 1,2-DCA were above the MCL 1,2-DCA-impacted shallow ground water has not been defined toward the east, and 1,2-DCA-impacted deeper ground water zone has not been defined toward the south, east and north A map illustrating the approximate extent of ' 1,2-DCA in shallow and deep ground water is presented on Figure 6 • EDB was detected in ground water sample EX-1 at a concentration of 290 µg/1 EDB has ' been detected intermittently in well EX-1, located near the former UST location 5.0. RECOMMENDATIONS Based on the results of this and previous investigations, AGE recommends ' Continued quarterly monitoring of the ground water monitoring network ' Advanced CeoEnvironmental,Inc I