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Geological Technics w. Page 2 <br /> ' Groundwater Monitoring Report <br /> Project No. 1030.2 <br /> May 15,2003 <br /> 1.0 GROUNDWATER MONITORING <br /> ' 1.1 Hydrogeology of Site <br /> On April 18, 2003, the depth to groundwater was measured in all of the monitoring wells <br /> prior to purging. Depths to groundwater, at the site, averaged 12.38 feet below the top of <br /> casing. The average groundwater elevation for the April 2003 event was 64.24 feet above <br /> ' mean sea level (MSL). This average corresponds with historical groundwater elevation <br /> measurements recorded at this site. <br /> ' Site-specific groundwater bearing and slope were calculated and found to be N49°E @ <br /> 0.0030 ft/ft. These results are consistent with historical groundwater bearing and slope for <br /> this site. <br /> Vertical groundwater gradients were calculated for the site using the MW-1/MW-1013 well <br /> pair and found to be positive. The site-specific vertical groundwater gradient is 0.0006 ft/ft. <br /> ' MW-1 is screened from 5 to 20 feet bgs and MW-101 is screened from 29.5 to 34.5 feet <br /> bgs. Vertical groundwater gradient calculations have been performed at regular intervals <br /> since the installation of MW-101 on April 12, 2002. The vertical gradients are <br /> approximately one order of magnitude less than the horizontal gradients. <br /> Groundwater elevation, bearing and slope were calculated using data gathered from MW-2, <br /> MW-3 and MW-4 during the April 18, 2003, monitoring event and the results are <br /> summarized in Table I of Appendix A. Table 2 of Appendix A summarizes the vertical <br /> groundwater gradient calculations. <br /> 1.2 Groundwater Sampling Procedure <br /> ' On April 18, 2003, Del-Tech Geotechnical Support Service personnel arrived on-site, <br /> opened the wells and measured the depth to water with an electrically actuated sounding <br /> ' tape. The water level reading was recorded to an accuracy of 0.01 foot. If free floating <br /> product had been suspected, a clear disposable bailer would have been used to gauge the <br /> interface. No floating product was observed during this sampling event. <br /> Stagnant water in the well casing was purged using a Waterra pump and dedicated <br /> tubing. <br /> The rate of well purging was monitored. The well was purged of at least three casing <br /> ' volumes until the groundwater parameters (temperature, conductivity and pH) had stabilized -� <br /> (Appendix Q indicating that water representative of actual aquifer conditions was entering <br /> ' the well. Groundwater parameter stabilization was characterized by three successive <br /> readings within 10%. <br /> 1 <br />