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13 November 2000 <br /> • AGE-NC Project No 99-0624 <br /> Page 3 of 4 <br />' contoured ground water elevations as measured on 05 September 2000 <br />' 3 2 LABORATORY RESULTS OF GROUND WATER SAMPLES <br /> Petroleum hydrocarbons quantified as TPH-g were detected in ground water samples collected from <br />' monitoring wells MW-1,MW-2 and MW-3 MTBE was detected in groundwater samples collected <br /> from monitoring wells MW-2 and MW-3 <br />' TPH-g was detected at concentrations as high as 1,800 micrograms per liter (µg/1) in the sample <br /> collected from MW-2, benzene and xylene compounds were detected at concentrations as high as <br />' 340 µg/1 and 63 µg/1 respectively The MW-4 sample had non-detectable concentrations of all <br /> hydrocarbons except benzene at 12µg/l,which exceeds the California State drinking water standard <br /> of 1 0 µg/1 <br />' MTBE was detected in monitoring wells MW-2 and MW-3 at concentrations of 2,300 µg/1 and 6 8 <br /> µg/l, respectively <br />'• Analytical results of the ground water samples for the third quarter - 2000 monitoring event are <br /> summarized on Table 2 The laboratory report (MAI Laboratory ID 46811-46814), QA/QC and <br />' chain-of custody are Included in Appendix B <br />' 4.0. SUMMARY/CONCLUSIONS <br /> The following conclusions were drawn from the results of the site investigation <br />' 0 The average depth to ground water and ground water elevation on 05 September 2000 in <br /> monitoring wells on-site was approximately 53 feet below surface grade and 14 30 feet <br />' below MSL, respectively <br /> • The inferred ground water gradient on 05 September 2000 was calculated to be 0 003'R/ft, <br />' generally toward the south,but fanning out towards the southwest and southeast <br /> • TPH-g was detected in ground water samples from monitoring wells MW-I to MW-3 on-site <br />' with the highest concentrations from samples collected from MW-2, however, there was a <br /> significant decrease in TPH-g concentration in MW-2 from the 17 May 2000 sample,which <br /> may be due to the drop in ground water elevation The data also shows that the TPH-g- <br />' impact to ground water extends laterally to the west and east as far as MW-1 and MW-2, <br /> • respectively TPH-g was not detected in the sample from MW-4 <br /> Advanced GeoEnveranmenta[,Inc <br /> I f <br />