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Geofogicaf7echnirs Inc. Page 2 <br /> Groundwater Monitoring Report <br /> Project No. 723.2 <br /> April 20,2001 <br /> 1.0 GROUNDWATER MONITORING <br /> t 1.1 Hydrogeology of Site <br /> A site-specific groundwater gradient and bearing was calculated from the depth to water <br /> measurements taken during the groundwater monitoring. The gradient was 0.0041 ft/ft <br /> flowing,N76°E. This is the sixth event where a site-specific groundwater gradient was <br /> calculated by resolving a'three-point problem using MW-4, MW-5 and MW-6. These wells <br /> were selected,because they are constructed relatively similar in regards to depth of screen <br /> interval.. The average elevation of groundwater under the site was 17.16 feet below mean <br /> sea level. Depths to water ranged from 27.15 —27.96 feet bgs. <br /> L <br /> Figure 2 is a groundwater gradient map for the December 4, 2000 event. Figure 3, <br /> Groundwater Gradient Rose Diagram includes historical groundwater direction and <br /> L gradients. <br /> This is the sixth event where the deep discretely screened well, MW-101, was monitored. A <br /> L shallow well has not yet been installed next to MW-101 so a vertical gradient cannot easily <br /> be calculated. The groundwater head in MW-101 is nearly equal (-0.02 feet) to the head in <br /> nearby wells MW-2 and MW-3 so it appears there was not a significant vertical gradient on <br /> LC December 4, 2000. <br /> Table 1 in Appendix A contains the groundwater elevations and gradients for the site. <br /> 1.2 Groundwater Sampling Procedure <br /> On December 4 2000 Del-Tech <br /> Geotechntcal,Support personnel arrived on-site, opened <br /> the wells, and measured the depth to water with an electrically actuated sounding tape: The <br /> water level readings were recorded to an accuracy of 0.01 foot. In wells where free-floating <br /> product was suspected, a clear disposable bailer is used to gauge the interface. During this <br /> monitoring no free product was noted. <br /> Stagnant water in the well casing was purged using a Waterra pump as recorded in the field <br /> logs (Appendix Q. The rate of well purging was monitored. The wells were purged of <br /> approximately three casing volumes and until the groundwater parameters (temperature, <br /> conductivity, and pH) had stabilized (Appendix C) indicating that water, representative of <br /> actual aquifer conditions, was entering the well. Groundwater parameter stabilization was <br /> characterized by three successive readings within 10%. <br /> Before a:sample was collected, the well's water level was allowed to recharge to at least <br /> �.' 80% of the initial level. All water removed from the monitoring well and not used as a <br />