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R604 UPDATE 26 1-21-1994 <br /> hydrocarbons since the June 24, 1991 All other wells have <br /> tested below 1 ppm gasoline range hydrocarbons since the March <br /> 29, 1992 sampling These analyses, when compared to those of <br /> December 15, 1991, substantiate the removal of hydrocarbons <br /> associated with the ground water, see Table 1 . <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 /> Analyses from the December 16, 1991 sampling round show that <br /> only MW1, MW2 , and MWS, had BTEXs, in very low concentrations <br /> None of the wells contained BTEXs in the March 5, and June 2, <br /> 1992 sampling, except MW5 During the September 11, 1992 <br /> sampling, sample results from MW1 detected only benzene (1 2 <br /> ug/L) and MW5 sample results indicated only the xylenes (4 . 1 <br /> ug/L) The December 7, 1992 sample results showed only MW5 to <br /> contain ethylbenzene (1 2 ug/L) and xylenes (35 ug/L) The most <br /> recent sampling (December 30, 1993) only MW5 contained xylenes at <br /> 2 2 ug/L At the time of the sampling MW5 was being utilized as <br /> a vapor extraction well . This pulling of the contaminants to the <br /> well consequently increased concentrations The VES was turned <br /> off that day. Below are the maximum contaminant levels (MCL) s <br /> that are applied for drinking water in the California <br /> MAXIMUM CONTAMINANT LEVELS (MCL) FOR PRIMARY DRINKING WATER, <br /> TITLE 22 or DHS <br /> Primary MCL <br /> (no adverse <br /> health affects) <br /> BENZENE 1 ug/L <br /> TOLUENE 1000 ug/L <br /> ETHYLBENZENE 700 ug/L <br /> Total XYLENES 1750 ug/L <br /> Vapor extraction has removed most 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 With this in mind, the "Present <br /> California Water Quality Goals" have been met for over 1 year, <br /> see Table 1 <br /> Fecal Coliform- <br /> From December, 1991 through February, 1992 , monthly fecal <br /> coliform samples were collected from monitor wells MW3 , MW4 , MW5 <br /> and MW6 Samples were again collected in June, 1992 , from <br /> monitoring wells MW3 , MW4 and MW6 During the September 11, 1992 <br /> sampling, MW3 and MW6 were dry, no fecal coliform samples were <br /> obtained Table 2 shows the results of these samples the only <br /> wells that have tested positive for fecal coliform are MW4 and <br /> MW5 As of June, 1992 all these wells are below detection <br /> limits, <2 2 MPN, for fecal coliform <br /> page 2 <br />