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19 May 1997 <br /> AGE-NC Project No 95-0137 <br /> ' Page 2 of 4 <br /> ' amber bottles Samples were stored in a dulled container and transported under chain-of-custody <br /> to McCampbell Analytical Laboratories (MAI) in Pacheco, California Each sample was analyzed <br /> in accordance with EPA Method 8015-m modified for gasoline for TPH-g, EPA Method 8015-M <br /> modified for diesel for TPH-d, and in accordance with EPA Method 602 for methyl-tert-butyl ether <br /> (MTBE) and volatile organic compounds, benzene, toluene, ethylbenzene and xylenes (BTE&X) <br /> 3.0. FINDINGS <br /> 31 GROUNDWATER GRADIENT AND FLOW DIRECTION <br /> Figure 3 - Relative Ground Water Elevation illustrates the relative ground water elevation on 27 <br /> March 1997 Depth to ground water at the site ranged from 16 30 to 17 12 feet The data indicates <br /> an average increase in ground water elevation at the site of 2 39 feet since December 1996 <br /> Historically, ground water flow direction at the site has varied from northwest to southeast with a <br /> consistently shallow gradient During March 1997, the ground water gradient was calculated to be <br /> 0 01437 ft/ft, with a northwesterly flow direction <br /> 3 2 PETROLEUM HYDROCARBON-IMPACTED GROUND WATER <br /> TPH-g was detected in wells MW-1 though MW-5 at concentrations as high as 5,300 parts per <br /> ' billion(ppb, reported as micrograms per liter) TPH-d was detected in wells MW-1 through MW-5 <br /> at concentrations up to 3,400 ppb (MW-3) <br /> ' Benzene was detected in the sample from MW-2 at 580 ppb, toluene was detected in MW-2 at a <br /> concentration of 29 ppb Ethylbenzene and xylenes were detected in samples collected from MW-1 <br /> and MW-2 at concentrations as high as 570 ppb (xylenes,MW-2) Analytical results of ground water <br /> ' samples are summarized in Table 2 -Analytical Results of Ground Water Samples The laboratory <br /> report (MAI Lab ID Numbers 74833 - 74837), QA/QC and chain-of-custody are included in <br /> ' Appendix B <br /> ' 4 0. CONCLUSIONS AND RECOMMENDATIONS <br /> • 4 1 CONCLUSIONS <br /> ' Based upon data collected during the March 1997 monitoring, AGE concludes the following <br />