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Ge01081ca17eckrucs kc. Page 2 I Groundwater Monitoring Report Project No. 1030.2 . March 10,2003 ' 1.0 GROUNDWATER MONITORING ' 1.1 Hydrogeology of Site On November 19, 2002, the depth to groundwater was measured in all of the monitoring ' wells prior to purging. Depths to groundwater ranged from a high of 1190 feet below the top of casing to a low of 12.65 feet below the top of casing. The average groundwater elevation for the November 2002 event was 64.30 feet above mean sea level (MSL). This ' average corresponds with historical groundwater elevation measurements recorded at this site. ' Site-specific groundwater bearing and slope were calculated and found to be N2$°E cr 0.0043 ft/ft. These results are consistent with historical groundwater bearing and slope for this site. ' Groundwater elevation, bearing and slope were calculated using data gathered from MW-1 MW-2 and MW-4 during the November 19, 2002, monitoring event. MW-3 was not used in ' the calculations this quarter because the well casing has been invaded by roots making depth to water measurements unreliable. Vertical groundwater gradients were calculated for the site using the MW-1/MW-101 well pair and found to be positive. The site-specific vertical groundwater gradient is 0.0006 ft/ft. MW-1 is screened from 5 to 20 feet bgs and MW-101 is screened from 30 to 35 feet bgs. Data from the well pair dates back to June 11, 2002, and calculations have been performed at quarterly intervals. The vertical gradients are approximately one order of magnitude less ' than the horizontal gradients. Figure 2 shows the location of the well cluster used for calculating vertical groundwater ' gradient in this report. Table I shows a summary of groundwater elevations and Table 2 shows vertical groundwater gradient calculations. t1.2 Groundwater Sampling Procedure On November 19, 2002, Del-Tech Geotechnical Support personnel arrived on-site, opened ' the wells and measured the depth to water with an electrically actuated sounding tape. The water level reading was recorded to an accuracy of 0.01 foot. If free floating product had been suspected, a clear disposable bailer would have been used to gauge the interface. No floating product was observed during this sampling event. ' Stagnant water in the well casing was purged using a dedicated Waterra pump. The rate of well purging was monitored. The well was purged of at least three casing volumes until the groundwater parameters (temperature, conductivity and pH) had stabilized (Appendix Q indicating that water representative of actual aquifer conditions was entering the well. Groundwater parameter stabilization was characterized by three successive readings within 10%.