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concentrations of vinyl chloride (4,500 ppb) and 1,1,1 -trichloroethane <br />(610 ppb) of the five wells sampled. Well W-1 was also the only well <br />with a vinyl chloride concentration above the regulatory detection <br />limit. Well W-2 had the lowest concentration of benzene (77 ppb). <br />Well W-3 exhibited the highest concentrations of methylene chloride <br />(11,000 ppb) and trichloroethylene (1,400 ppb). Well W-4 exhibited <br />the highest concentrations of benzene (930 ppb), 1,2-dichloroethane <br />(110 ppb), tetrachloroethylene (2,200 ppb), and chloroform (240 ppb). <br />Well W-4 was the only well with a chloroform concentration above the <br />regulatory detection limit. Ethylene dibromide and carbon <br />tetrachloride were not detected in any well sample. <br />•.�� .. a ��. <br />Two integrated surface walks were conducted at the site. Analytical <br />results of the sampling events for VOCs and field measurements of <br />methane are summarized in Table 4. Benzene and 1,1,1 -trichloroethane <br />were detected in both surface walk samples. The concentrations were <br />below their respective regulatory detection limits. No other VOCs <br />were detected. <br />An OVA was used to detect total organics as methane during the inte- <br />grated surface walks. Field measurements using an OVA indicated <br />methane levels of 3 and 23 ppm for SW -1 and SW -2, respectively. <br />PJ9 9390405.00D 2-9 Rev. 0 05/18/88 <br />Mon Associates — <br />