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Geological Tec/utics leu Page 2 Groundwater Monitoring Report Project No 662 2 July 7, 2005 1.0 GROUNDWATER MONITORING ' 1.1 Hydrogeology of Site ' The dominant soil type in the upper 40 feet of the subsurface geologic soils investigated is sand, fine to course grained, interbedded with thinner units of plastic clay i Two additional monitoring wells (MW-5 & MW-6) and one extraction well (EW-2) were installed at the site in October 2004 The two monitoring wells are screened from 40 — 45 feet below grade surface (bgs) or approximately ten feet below historical groundwater table levels The new extraction well is screened from 22 - 32 feet bgs and across the historical water table All of the site's wells were surveyed on November 19, 2004 in accordance with Geotracker requirements The new and existing wells were divided into two aquifer zones in ' which the wells are screened Shallow Aquifer(screened 19—40 feet bgs) MW-1, MW-2, MW-3 and EW-2 Deep Aquifer(screened 37— 53 feet bgs) MW-5, MW-6, MW-104 and EW-1 Based on these aquifer divisions groundwater gradients were calculated for both the shallow and deeper aquifer On May 26, 2005, the water table well (shallow) groundwater elevation averaged 15 72 feet mean sea level (MSL) This equates to approximately 23 feet bgs and represents an increase of 124 feet since the February 2005 monitoring event Groundwater ' gradient calculations indicate that the flow in the shallow wells MW-1, MW-2 and MW-3 was SWE with a slope of 0 002 ft/ft The deeper aquifer gradient was N82°E with a slope of 0 001 ft/ft Groundwater elevation and gradient data are summarized in Tables 1 and 2, Appendix A ' Gradient directions are shown in Figure 2A Shallow Groundwater Gradient Map, and Figure 2B Deep Groundwater Gradient Map The historical groundwater gradients are shown in Figure 3A Shallow Gradient Rose Diagram , and Figure 3B Deep Gradient Rose Diagram ' As noted in Figure 3A the site's shallow aquifer displays a predorninantly easterly groundwater direction Additional monitoring is necessary to determine trends in the deeper aquifer 1.2 Groundwater Sampling Procedure On May 26, 2005, Don Light of Del-Tech mobilized to the site to perform the groundwater monitoring event Depth to groundwater measurements were completed in all of the site's ' wells and seven of eight wells were sampled Extraction well EW-1 is not sampled due to its long screen length that intercepts both the shallow and deep aquifer zones