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i R604 :UPDATE 22 9-17-1993 Dissolved Petroleum Hydrocarbons in Ground Water (EPA method 5030 TF$ as gasoline) : Dissolved total fuel hydrocarbons, gasoline range (TFHg) is present in MW5, MW2, and MW7 which contained 0 . 64, 0 . 23 and 0 . 11 parts per million (mg/L) respectively All other wells sampled, MW1, MW3 , MW4 and MW6, were below detection limits on June 18, 1993 . MW5 has tested below 1 ppm for gasoline range hydrocarbons since the June 24, 1991 . This is the first time MW7 has tested above the detection limits. The laboratory reported that MW2 does not match gasoline but contained a single peak. Another sample was obtained from MW2 on August 20, 1993 and analyzed for Volatile Organic Compounds using EPA Method 624 . This analysis showed the single compound as 1, 2-Dichloroethane at 520 ug/L (ppb) . All other wells have tested below 1 ppm gasoline range hydrocarbons since the March 29, 1992 sampling These analyses, when compared to those of December 15, 1991, substantiate the removal of hydrocarbons associated with the ground water, see Table 1 . Before vapor extraction, November 21, 1990, gasoline range hydrocarbons were detected in MW1 (2 mg/L) , and MW5 (31 mg/L) . BTEX in Ground Water (EPA method 602) Analyses from the December 16, 1991 sampling round show that only MW1, MW2, and MWS, had BTEXs, in very low concentrations . None of the wells contained BTEXs in the March 5, and June 2, 1992 sampling, except MW5 . During the September 11, 1992 sampling, sample results from MW1 detected only benzene (1 .2 ug/L) and MW5 sample results indicated only the xylenes (4 . 1 ug/L) The December 7, 1992 sample results showed only MW5 to contain ethylbenzene (1 .2 ug/L) and xylenes (35 ug/L) The most recent sampling (June 18, 1993) only MW5 and MW7 contained ethylbenzene at 5 .4 and 0 .4 ug/L and xylenes at 120 and 15 ug/L respectively MW5 is presently being utilized as a vapor extraction well This pulling of the contaminants to the well consequently increased concentrations Below are the maximum contaminant levels (MCL) s that are applied for drinking water in the California: MAXIMUM CONTAMINANT LEVELS (MCL) FOR PRIMARY DRINKING WATER, TITLE 22 or DHS. Primary MCL (no adverse heal th affects) BENZENE 1 ug/L TOLUENE 1000 ug/L ETHYLBENZENE 700 ug/L Total XYLENES 1750 ug/L Vapor extraction has removed most BTEXs from the ground water as shown by sample results obtained from the monitoring wells The Primary MCLS have been obtained since September 11, 1992 , when MWI, tested 1 . 2 ppb benzene. With this in mind, the "Present page 2