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Mr Harlin Knoll Page 2 of 4 • further define that lateral extent of groundwater contamination beneath the site The wells were subsequently developed and sampled on November 4, 2002 The installation, development, and sampling of wells MW5, MW6, and MW7 are summarized in the January 8, 2003 Groundwater Monitoring Well Installation Report prepared by Ground Zero 2.2 Groundwater Monitoring and Sampling I An experienced Ground Zero field technician monitored and sampled wells MWl through MW7 on December 5, 2002 Groundwater elevations were calculated by measuring the depth to groundwater in each well and subtracting the measured value from the respective wellhead elevation The depth to groundwater in the wells ranged from 7 12 feet below the top of the well casing (btoc) in well MW6 to 9 74 feet btoc in well MW1 Groundwater elevations fell an average of 103 feet between November 4, 2002 and December 5, 2002 Groundwater elevations fell an average of 1 83 feet between September 4, 2002 and December 5, 2002 Groundwater generally flowed west-northwest with an average gradient of 0 0014 ft/ft, or approximately 7 5 feet per mile A potentiometric surface map for December 5, 2002 is presented on Figure 2 Groundwater monitoring data are summarized in Table 1 Monitoring data sheets are included in Attachment A At least three well casing volumes of water were purged from monitoring wells MW1 through MW7 prior to sampling Temperature, pH, and electrical conductivity were measured in • groundwater during the purging process Samples were collected after the measured parameters stabilized and water levels recovered to at least 80% of pre-purged levels Purged groundwater was contained in appropriately labeled DOT-approved 55-gallon drums, which are stored onsite pending disposal Purge logs are included in Attachment A Groundwater samples were delivered under chain of custody protocol to Argon Laboratories (ELAP #2359) Samples were analyzed for the presence of BTEX, 1,2-DCA, EDB, and oxygenated gasoline additives using EPA method 8260B 2.3 Waste Soil Pile Sampling Two soil samples were collected from the stockpiled soil to determine if any residual hydrocarbons remain The samples were collected approximately six inches below the surface at locations that previously contained low levels of residual petroleum hydrocarbons The samples were transported to Argon Laboratories under chain of custody where they were composited into one sample and analyzed for the presence of TPHd, and TPHg by EPA Method 8015M, and for BTEX by EPA Method 8020 3.0 GROUNDWATER ANALYTICAL RESULTS No BTEX constituents were present above the laboratory method detection limits (MDLs) in . any site well Methyl-tert butyl ether (MTBE) was the only chemical of concern detected at the site MTBE was detected in wells MW 1, MW3, MW4, and MW5 at 8 9 parts per billion G 1Data1GROL)NDZE\Barnyard-Manser\Reports\QMR14QM2002 doe