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Ms Lori Duncan Page 2 of 3 Groundwater Monitoring Monitoring wells MW 1 through MW4 were monitored for water level elevations and wells MW 1, MW2 and MW4 were purged and sampled on June 10, 2002 No samples were collected from well MW3 due to the presence of free product The depths to water in wells MW1, MW2, and MW4 were monitored using an electronic water level indicator The depth to water and depth to product in well MW3 was measured using an electronic water/hydrocarbon interface probe Groundwater elevations were calculated by subtracting the measured depth to groundwater in each well from the respective wellhead elevation The depth to groundwater in the wells on June 10, 2002 ranged from 22 62 to 23 30 feet below ground surface (bgs) Groundwater fell approximately 0 11 feet between March 12, 2002 and June 10, 2002 Groundwater flowed in a northeasterly direction with an average gradient of 0 003 ft/ft, or approximately 16 ft/mile A potentiometric surface map for June 10, 2002 is shown on Figure 2 Groundwater monitoring data are summarized in Table 2 Monitoring data sheets are included in Attachment B Groundwater Sampling Due to the presence of free product in well MW3, groundwater samples were only collected from wells MW 1, MW2 and MW4 A minimum of three well casing volumes of water was purged from each well using a bailer prior to collecting groundwater samples The physical parameters of temperature, pH and electrical conductivity were measured during the purging process All downhole equipment was decontaminated between wells using a solution of laboratory-grade detergent, then double rinsing in separate containers of clean rinse water Groundwater samples were collected using dedicated, disposable bailers after the physical parameters had stabilized and water levels recovered to within 80% of their pre-purged levels The samples were placed into an ice chest refrigerated to approximately 4°C and transported to Argon Laboratories (ELAP #2359)under chain of custody protocol Well purge logs are included in Attachment B GROUNDWATER ANALYTICAL RESULTS Groundwater samples were analyzed for VOCs, includmg oxygenated gasoline additives and the lead scavengers 1,2-dichloroethane (1,2-DCA) and ethylene dibromide (EDB) using EPA method 8260B No samples were collected from well MW3 due to the presence of free product No oxygenated gasoline additives, EDB or 1,2-DCA were detected in the groundwater samples collected from wells MWl, MW2, or MW4 PCE was detected in wells MW1, MW2, and MW4 at concentrations of 20 parts per billion (ppb), 17 ppb, and 17 ppb, respectively Chloroform was also detected in wells MW 1, MW2, and MW4 at 3 0 ppb, 2 5 ppb, and 3 1 ppb, respectively Only PCE was detected at levels exceeding its primary Maximum Contaminant Level (MCL) established by the State of California Department of Health Services The established primary MCL for PCE is 5 0 ppb Groundwater analytical results are summarized in Table 3 Attachment C contains laboratory 0 1Data1GROUNDZEIGABBARDIreports�2QM2002 doc