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03 December 2003 <br /> AGE-NC Protect No 95-0184 <br />' Page 4of5 <br />' 4.0. SUMMARY AND CONCLUSIONS <br /> Based upon data collected from the site, AGE concludes the following <br />' • Ground water elevations at the site averaged approximately 23 51 feet below MSL All <br /> ground water wells except VW-3,VW-4 and VW-5B were"drowned", with water levels as <br />' high as 19 feet above the screened Intervals of the drowned wells <br /> • The ground water was inferred to flow generally northeast across much of the site at a <br />' gradient of approximately 0 004 to 0 007 foot/foot This ground water flow direction is <br /> consistent with the last 22 monitoring events (Table 4) <br /> • Detectable concentrations of TPH-g were found in all of the ground water wells sampled, <br />' though concentrations overall decreased significantly as compared to the previous quarter <br /> One or more BTEX compounds were found in all ground water samples collected except for <br /> the sample from MW-7 These samples contained one or more analytes at concentrations <br /> above California's Maximum Contaminant Levels (MCLS) <br /> • No free product was measured during this sampling event,however,most of the well screens <br /> are drowned and are not likely to produce direct evidence of free product <br /> • MTBE was detected in samples from wells MW-4, VW-2B, VW-3 and VW-4 at <br />' concentrations ranging from 67 gg/1(MW-4)to 550 µg/l (VW-4) 1,2-DCA was detected in <br /> MW-2, MW-4 and VW-2B through VW-5C at a maximum concentration of 410 µg/1 <br /> (VW-4), EDB was detected in MW-4 and VW-2B at a maximum concentration of 110 pg/1 <br /> I (VW-2B) The concentrations of MTBE, 1,2-DCA and EDB In the ground water samples <br /> exceed the MCLs for drinking water <br /> • Naththalene, 1,2,4-tnmethylbenzene, 1,3,5-tnmethylbenzene and n-propylbenzene were <br /> detected in ground water samples at concentrations above the DHS-recommended drinking <br /> water Action Levels <br /> I • The vertical and lateral extent of impacted soil and ground water has not yet been defined <br /> 5.0. RECOMMENDATIONS <br /> I Based upon data collected from the site, AGE recommends continued quarterly ground water <br /> monitoring The fourth quarter 2003 monitoring event is scheduled for December 2003 AGE is <br /> currently preparing a work plan to further delineate the vertical and lateral extent of impacted ground <br /> water on- and off-site, as requested in a meeting with the EHD on 12 June 2003 <br /> IAdvanced GeoEnvironmental,Inc <br /> I <br />