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I I06 October 1997 AGE-NC Project No 95-0143 ' Page 2 of 4 ' container,to McCampbell Analytical,Inc (MAI)in Pacheco,California The samples were analyzed for total petroleum hydrocarbons quantified as gasoline (TPH-g) by EPA Method 5030/8015 modified, for volatile aromatic compounds (benzene, toluene, ethylbenzene and xylenes BTE&X) ' with methyl tertiary-butyl ether (MTBE) in accordance with EPA Method 602, and for oxygenated volatile organics, in accordance with EPA Method 8240/8260 2 3 WATER DISPOSAL IOn 31 July 1997, water stored on-site from monitoring well purge procedures was disposed The water was transported by Nor Cal Oil of Denair California to Ainericlean, Inc in Silver Springs, I Nevada Approximately 220 gallons of water were disposed The Hazardous Waste Manifest is included in Appendix C ' 30 FINDINGS �r 3 1 RELATIVE GROUND WATER ELEVATION AND GRADIENT The relative elevation of ground water in each well was calculated by subtracting the depth to water from the surveyed casing elevation (Table 1) Ground water elevation decreased an average of 0 16 feet between May and August 1997 The approximate hydiauhc gradient was calculated to be 0 0035 ft/ft with a northerly flow direction north of the site, similar to gradients measured at the Madison site Howevei, a shallower giadient of 0 0012 ft/it was measured on the southern poition of the subject piopeity Relative ground water cle\ation contours for the August 1997 monitoring event ' aie illustrated in Figure 3 ' 32 ANALYTICAL RESULTS OF WATER SAMPLES During the August 1997 monitoring event, TPH-g was detected at concentrations of 210,000 parts ' per billion(ppb, reported as micrograms per liter), 950 ppb, 1,800 ppb and 25,000 ppb, in samples from MW-3, MW-6, MW-7 and MW-9, respectively BTE&X compounds were detected in samples from the same wells and MW-14 at concentrations as high as 39,000 ppb (toluene in sample from IMW-3) MTBE was detected in MW-3, MW-7, and MW-9 at concentrations of 120 ppb, 6 3 ppb, and 90 ppb, respectively IChloroform and methyl ethyl ketone were detected in MW-10 at concentrations of 2 3 ppb and 1 1 ppb, respectively 1,2-Dichloroethane and di-isopropyl ether (DIPS) were dEtected in MW-14 at concentrations of 13 ppb and 1 2 ppb, respectively Chloroform was detected in MW-16 at a .ithancetl CeoEmironntental,Inc