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Ms Lori Duncan August 7, 2001 Page 2 of 3 monitoring data are summarized in Table 1 Monitoring data sheets are included in Attachment A Due to the presence of free product in well MW3, groundwater samples were only collected from wells MWI, MW2 and MW4 A minimum of three well casing volumes of water was purged from each well prior to sampling The physical parameters of temperature, pH and electrical conductivity were measured during the purging process Groundwater samples were coflected after the physical parameters had stabilized and water levels recovered to their pre-purged levels The samples were placed into an ice chest cooled to approximately 4° centigrade and transported to Argon Laboratories (FLAP#2359)under chain of custody protocol Well purge logs are included in Attachment A WASTE DISPOSAL Groundwater purged from the site wells was contained in appropriately labeled DOT-approved 55- gallon drums and stored at the site Approximately 330 gallons of wastewater were removed from the site on July ll, 2001 and transported by American Valley Waste Oil, Delhi, CA (EPA Id # CAL 000827878) to Seaport Environmental, Redwood City, CA(EPA Id# CAL 0000325058)for disposal GROUNDWATER ANALYTICAL RESULTS Groundwater samples were analyzed for the presence of TPHg and TPHd using EPA method 8015M, BTEX using EPA method 8020, VOCs, including oxygenated gasoline additives, 1,2-dichloroethane, . and ethylene dibromide, using EPA method 8260B, TRPH using EPA Method 418 1, and dissolved (filtered)lead using EPA Method 6010/200 7 No gasoline constituents, including TPHg, TPHd, TRPH, BTEX, methyl-tert-butyl-ether (MTBE), or lead, were detected in groundwater samples collected from wells MW 1, MW2, or MW4 Low levels of tetrachloroethene (PCE) were detected in all three wells sampled, and chloroform was detected in wells MW 1 and MM2 PCE in groundwater ranged from 15 parts per billion (ppb) to 22 ppb, and chloroform ranged from<2 0 ppb to 4 7 ppb Groundwater analytical results are summarized in Tables 2 and 3 Attachment B contains laboratory reports and chain of custody documentation SUMMARY Groundwater levels and the direction of groundwater flow beneath the site were consistent with those measured in December 2000 No petroleum hydrocarbon constituents were detected in wells MW1, MW2, or MW4, but approximately four inches of floating product was measured in well MW3 The product was determined by the laboratory to be primarily in the motor oil range PCE was again detected in site wells, ranging from approximately 15-22 ppb The detected levels of PCE exceed the Maximum Contaminant Level (MCL)of 5 0 ppb CONCLUSIONS AND RECOMMENDATIONS Groundwater analytical results indicated that petroleum hydrocarbon contanvnation is present in groundwater in the immediate viciiuty of the former UST but does not extend to perimeter wells located approximately 20 feet southwest, 35 feet north, and 40 northeast of the former UST PCE G1Data1GROLINDZEIGABBARD\reports12QM2001 doc