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Ms Lori Duncan Page 2 of 3 (. 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 September 19, 2002 ranged from 24 13 to 24 84 feet below ground surface (bgs) Groundwater fell an average of 1 55 feet in site wells between June 10, 2002 and September 19, 2002 The calculated groundwater gradient for September 19, 2002 was 0 0027, or approximately 14 5 feet per mile, toward the northeast A potentiometric surface map for September 19, 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, including 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 PCE was detected in wells MW1, MW2, and MW4 at concentrations of 16 parts per billion (ppb), 14 ppb, and 15 ppb, respectively Chloroform was detected in wells MW2 and MW4 at 2 3 ppb and 2 8 ppb, respectively Cis-1,2-dichlorethene (cis-1,2-13CE) and trichloroethene (TCE) were detected in well MW1 at 2 8 ppb and 3 5 ppb, respectively No cis-1,2-DCE or TCE were detected in wells MW2 or MW4 Concentrations of chloroform, TCE and cis-1,2 DCE detected at the site remain below their respective primary Maximum Contaminant Levels (MCLS) of 80 ppb, 5 ppb and 6 ppb, as established by the State of California Department of Health Services PCE was present at levels exceeding its primary MCL of 5 0 ppb in all site wells, however No oxygenated gasoline additives, EDB or 1,2-DCA was detected in the groundwater samples collected from wells MW 1, MW2, or MW4 Groundwater analytical results are summarized on Table 3 Attachment C contains laboratory reports and chain of custody documentation G1Data1GROUNDZEIGABBARDIreports13QM2002 doc