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'F �r Ms Lori Duncan a Page 2 of 3 Product thickness in the well over time, are included in Attachment A 2.2 Groundwater Monitoring Water level elevations were monitored in wells MW 1 through MW4 on March 3, 2003 The depth to water and depth to product in well MW3 were measured using an electronic water/hydrocarbon interface probe Depths to water in wells MWl, MW2, and MW4 were measured using an electronic water level indicator 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 March 3, 2003 ranged from 24 36 to 25 10 feet below the tops of the well casings (btoc) The potentiometric surface rose an average of 0 50 feet since the last event Groundwater flowed in a northeasterly direction with a calculated gradient of 0 003 feet per foot (approximately 16 feet per mile) A potentiometric surface map for March 3, 2003 is shown on Figure 2 Groundwater monitoring data are summarized in Table 2 Monitoring data sheets are included in Attachment B 2.3 Groundwater Sampling Due to the presence of free product in well MW3, groundwater samples were only collected from wells MW1, MW2 and MW4 Prior to collecting samples, an experienced Ground Zero technician purged a minimum of three well casing volumes of water from each well using dedicated bailers During the purging process, the technician measured physical parameters of temperature, pH and electrical conductivity All downhole equipment was decontaminated between wells by washing with a solution of laboratory-grade detergent, and then double rinsing with clean rinse water i 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 3.0 GROUNDWATER ANALYTICAL RESULTS Groundwater samples were analyzed for VOCs, including oxygenated gasoline additives and lead scavengers, using EPA method 8260B No samples were collected from well MW3 due to the presence of free product No gasoline constituents (BTEX, oxygenated additives, or lead scavengers) were detected above method detection limits (MDLs) in groundwater samples collected from wells MW1, MW2, or MW4 Tetrachloroethene (PCE) was detected in wells MW1, MW2, and MW4 at concentrations of 21 parts per billion (ppb), 15 ppb, and 12 ppb, respectively Chloroform was detected in wells MW1, MW2, and MW4 at 2 8 ppb, 3 7 ppb, and 2 8 ppb, respectively No other VOCs were detected the wells Groundwater analytical results are summarized on Table 3 Attachment C GIGROUNDZEIGABBARDIreports1200311 QM2003 doc