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CLOSURE REQUEST 5-31-94 • RESULTS - WATER TOTAL PETROLEUM HYDROCARBONS Floating Product: No floating product has ever been observed in any of the monitoring wells or borings at this site. � Dissolved Petroleum Hydrocarbons in Ground Water (EPA method 5030 TFH as gasoline) The February 16, 1994 ground water sample results show a continuance of below detection limits for gasoline petroleum hydrocarbons, benzene, toluene and ethylbenzene. MW5 has tested below 1 ppm for gasoline range hydrocarbons since the June 24 , 1991 . 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 MW5, had BTEXs, in very low concentrations . None of the wells contained BTEXs in the March 5, and June 2 , 1992 sampling, except MW5 . The laboratory detected only benzene (1 .2 ug/L) in MWl and only the xylenes (4 . 1 ug/L) in MW5 in the September 11, 1992 The December 7, 1992 sample results showed only MW5 to contain ethylbenzene (1 .2 ug/L) and xylenes (35 ug/L) Results from the most recent sampling (February 16, 1994) show only MW5 containing xylenes at 2 .5 ug/L. Prior to this sampling MW5 was being utilized as a vapor extraction well . This pulling of the contaminants to the well consequently increased concentrations . The VES was turned off on December 30, 1993 and at that time the Xylenes were at 2 . 2 ug/L. Samples obtained on February 16, 1994 , showed only xylenes in MW5 at 2 . 5 ug/L. This latest sampling indicates that the samples obtained when the VES is active are representative of ground water conditions and is not somehow attenuating the samples Fecal Coliform: From December, 1991 through February, 1992, monthly fecal coliform samples were collected from monitor wells MW3 , MW4, MW5 and MW6 Samples were again collected in June, 1992, from monitoring wells MW3 , MW4 and MW6 . During the September 11, 1992 sampling, MW3 and MW6 were dry; no fecal coliform samples were obtained. Table 2 shows the results of these samples . the only wells that have tested positive for fecal coliform are MW4 and MW5 . As of June, 1992 all these wells are below detection page3l