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• 15 January 2001 <br /> AGE-NC Protect No 99-0624 <br /> Page 3of4 <br /> a southwesterly direction Figure 3 illustrates the contoured ground water elevations as measured on <br /> 06 December 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 /> monitonng wells MW-1,MW-2 and MW-3 MTBE was detected in ground water samples collected <br /> from monitoring wells MW-2 and MW-3 <br /> TPH-g was detected at concentrations as high as 1,100 micrograms per liter (µg11) in the sample <br /> I collected from MW-2, benzene and xylene compounds were detected at concentrations as high as <br /> 110 ug/1 and 58 µg/1 respectively The MW-4 sample had non-detectable concentrations of all <br /> hydrocarbons except benzene at 1 3 ugll,which exceeds the maximum contaminant level(MCL)for <br /> California drinking water (1 0 gg/1) <br /> MTBE was detected in monitoring wells MW-2 and MW-3 at concentrations of 1,300 µg/1 and 12 <br /> µg11, respectively <br /> Analytical results of the ground water samples for the fourth quarter - 2000 monitoring event are <br /> I summarized on Table 2 The laboratory report (MAI Laboratory ID 55253-55256), QA/QC and <br /> chain-of-custody are included in Appendix B <br /> 4.0. SUMMARY/CONCLUSIONS <br /> IThe following conclusions were drawn from the results of the site investigation <br /> • The average depth to ground water and ground water elevation on 06 December 2000 in <br /> monitoring wells on-site was approximately 52 feet below surface grade and 13 4 feet below <br /> MSL, respectively R , <br /> • The inferred ground water gradient on 06 December 2000 was calculated to be 0 002 ft/ft <br /> towards the south-southwest <br /> • TPH-g was detected in'ground water samples from monitoring wells MW-1 to MW-3, the <br /> highest concentration was detected from the sample collected from MW-2, although it has <br /> declined from a high of 8,900 ptg/l recorded in May 2000 TPH-g was not detected in the <br /> sample from MW-4 <br /> • BTEX compounds were detected in the water samples collected from all four monitoring <br /> wells, the MW-2 sample had the highest concentrations <br /> Advanced GeoEnvironmental,Inc <br />