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groundwater samples collected from monitoring wells MW-5 and MW-6 Both of these wells are screened in the first zone encountered with the bottom of the zone extending to a depth of no greater than 19-feet bgs Monitoring well MW-5 is located between the USTs and the pump island near West Yosemite Avenue Monitoring well MW-6 is located between the USTs and the site building BTEX concentrations in groundwater samples collected from these two wells exceeded DTSC MCLS for drinking water The high toluene and total xylenes concentrations in these samples, relative to the benzene concentrations, and lack of oxygenates in these samples suggest an older release Benzene concentrations in groundwater samples collected from monitoring wells MW-7 and MW-8 also exceeded the DTSC MCLs for drinking water These wells are screened in deeper zones and are more indicative to possible contamination in a zone which could be used for drinking water In fact, the on-site drinking water well is screened in this zone The benzene concentration in monitoring well MW-9, although just over the DTSC MCL for drinking water, indicates that benzene is present in groundwater at concentrations dust above DTSC MCLs only 25-feet from the drinking water well in the same zone in which the drinking water well is screened Ethylbenzene, toluene, total xylenes and 1 ,2-dichloropropane were also detected in both of these borings, although at concentrations below DTSC MCLs for drinking water Naphthalene and isopropylbenzene were also detected in groundwater samples collected from monitoring well MW-7 These are currently non- regulated compounds There were no compounds detected at concentrations above DTSC MCLs for drinking water in the groundwater samples collected from monitoring wells MW-8 and MW-10, both screened below 100-feet bgs However, TPH-D and 1 ,2-dichloropropane were detected in groundwater samples collected from both of these wells at concentrations below drinking water standards Toluene and total xylenes were detected in groundwater samples collected from monitoring well MW-8 at concentrations below drinking water standards 1-methyl 2-pyrrolidinine, a compound which is used as both a solvent and in pesticides, was also detected in the deeper monitoring wells It is ASE's opinion that the 1,2-dichloropropane, and possibly the 1 -methyl 2-pyrrolidinine, are not likely related to on-site sources since they are detected in only the deeper groundwater samples and not in shallow Franks One Stop Report - June 1999 - 12-