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UPDATE 30 11-11-94 <br /> Dissolved Petroleum Hydrocarbons in Ground Water (EPA method 5030 <br /> TFH as gasoline) <br /> The October 10, 1994 ground water sample results show a <br /> continuance of low or below detection limit values for gasoline <br /> petroleum hydrocarbons. MW5 has tested below 1 ppm for gasoline <br /> range hydrocarbons since the March 29, 1991 . All other wells <br /> have tested below 1 ppm gasoline range hydrocarbons since the <br /> November 21, 1990 sampling. These analyses, when compared to <br /> those of December 15, 1991, substantiate the removal of <br /> hydrocarbons associated with the ground water, see Table 1 <br /> This latest sampling (October 10, 1994) shows below detection <br /> levels in all wells except MW5 which showed gasoline range <br /> hydrocarbons at 0 1 mg/L <br /> Before vapor extraction, November 21, 1990, gasoline range <br /> hydrocarbons were detected in MW1 (2 mg/L) , and MW5 (31 mg/L) . <br /> BTEX -in Ground Water (EPA method 602) <br /> All monitoring wells have tested below detection limits for <br /> Benzene, Toluene, Ethylbenzene and Xylenes (BTEX) for over one <br /> year with the exception of MW5 which had only Xylenes during the <br /> February 16, 1994 sampling in concentrations of 2 5 ug/L and the <br /> October 10, 1994 sampling in concentrations of 2 0 ug/L The <br /> July 21, 1994 sampling showed all wells to be below detection <br /> limits for BTEX <br /> Below are the maximum contaminant levels (MCL) s that are applied <br /> for drinking water in California <br /> MAXIMUM CONTAMINANT LEVELS (MCL) FOR PRIMARY DRINKING WATER, <br /> TITLE 22 or DHS <br /> Primary MCL Secondary MCL <br /> (no adverse (taste/odor) <br /> health affects) <br /> BENZENE 1 ug/L <br /> TOLUENE 1000 ug/L 42 ug/L <br /> ETHYLBENZENE 700 ug/L 29 ug/L <br /> Total XYLENES 1750 ug/L 17 ug/L <br /> Vapor extraction has removed the BTEXs from the ground water as <br /> shown by sample results obtained from the monitoring wells . The <br /> primary MCLS have been obtained since September 11, 1992, when <br /> MW1, tested 1 2 ppb benzene The secondary MCLs have been met <br /> since June 18, 1993 , when MW5 tested 120 ug/L Xylenes . The <br /> Secondary levels of the "Present California Water Quality Goals" <br /> have been met for more than a year, see Table 1 <br /> page3 <br />