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Mr Jeff Wong ' Page 2 of 4 �t 3 0 QUARTERLY SITE WORK ' 3 1 Groundwater Elevation Measurements ' A Ground Zero technician monitored water levels in all site wells, and collected groundwater samples from monitoring wells MW2 through MW14B and vapor well VWl on March 16, 2004 and March 17, 2004 ' The depth to groundwater was measured in each well prior to purging Groundwater elevations were calculated by subtracting the measured depth to water from the respective well head elevation ' The measured depth to groundwater below the tops of the well casings (btoc) in the A Zone monitoring wells ranged from 65 16 feet in well MW2 to 73 24 feet in well MW1 Groundwater ' elevations in the A Zone ranged from 33 08 feet below mean sea level (MSL) in well MW2 to 42 16 feet below MSL in well MWl Groundwater levels in the A Zone wells that were not affected by pumping from well MW1 rose an average of 0 99 feet between December 10, 2003 and March 16, ' 2004 By comparison, the groundwater elevation in shallow monitoring wells within 50 feet of the pumping well (MW2, MW4, VEW1) rose an average of 0 79 feet and the groundwater elevation in the extraction well (MW1) fell by 4 71 feet during the same period ' The groundwater level in B Zone wells MW913 and MW14B measured 64 86 feet btoc and 65 65 feet btoc (33 27 feet and 33 42 feet below MSL), respectively Groundwater elevations the B Zone ' wells rose an average of 1 02 between December 10, 2003 and March 16, 2004 The groundwater elevation in C Zone well MW 13C was measured at 66 17 feet btoc (33 99 feet below MSL), a rise of 0 99 feet between December 10, 2003 and March 16, 2004 ' Groundwater in the A Zone aquifer on March 16, 2004 generally flowed in a northeasterly direction, although a cone of depression is evident around well MW1, which serves as the extraction well ' The groundwater gradient across the site was approximately 0 0012 feet per foot Table 4 summarizes groundwater elevations in site monitoring wells Figure 2 presents a potentiometric surface map generated using the March 16, 2004 monitoring data Attachment C contains field logs 3.2 Groundwater Sampling and Analysis An experienced Ground Zero technician purged at least three well casing volumes of water from monitoring wells MW2 through MW14B and vapor well VWi prior to sampling A sample was collected from MW 1 on March 8, 2004 as part of the treatment system monitoring (sample ' designated INF, Table 1) The technician measured the temperature, pH and electrical conductivity of the water during the purging process Samples were collected after the physical parameters stabilized and water levels in the wells recovered to at least 80% of their respective pre-purged levels The samples were temporarily stored in an ice chest refrigerated to a temperature of approximately 4°C and delivered under chain of custody protocol to Argon Laboratories (ELAP #2359) for analysis Purged groundwater was contained in appropriately labeled DOT-approved 55- gallon drums in accordance with 49 CFR part 172 and 40 CFR part 262, and will eventually be processed through the groundwater treatment system Copies of field data sheets and purge logs are included in Attachment C G 1GROUNDZ$1TULEBURG1ReporlslQMR1200311QM2004 doc