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GeologICAI Teckrifcs Inc Page 5 ' Groundwater Monitonng Report Project No 425 2 November 8,2005 Zone C ' The average groundwater elevation in Zone C for the July 20, 2005 monitoring event was 73 60 feet AMSL This represents an increase of 0 42 feet since the April 11, 2005 monitoring event Groundwater bearing and slope average N67°W and 00023 ft/ft, ' respectively Bearing is suspect due to the linear positions of MW-101, MW-102, and MW- 201 The groundwater contour map (Figure 5) suggests the groundwater bearing is in a northerly direction Bearings recorded in Zones A and B would substantiate a northerly ' bearing in Zone C Table 4 summarizes the groundwater data from the Zone C Figure 7 shows the groundwater ' gradients for July 20, 2005 groundwater monitoring event l Zone D ' The groundwater elevation in Zone D is 73 97 feet AMSL This represents an increase of 0 22 feet from the April 2005 monitoring event Groundwater bearing and slope for this zone cannot be calculated because there is only one well associated with this zone Table 5 ' summarizes the groundwater data from the Zone D 1.4.3 Vertical Groundwater Gradients Vertical groundwater gradients were calculated using groundwater-monitoring wells MW- 2/MW-2X (Zone A/Zone B well pair) and groundwater monitoring wells MW-2X/MW-202 (Zone B/Zone D well pair) (Table 6) The site-specific vertical groundwater gradient for July ' 20, 2005 monitoring event for the MW-2/MW-2X pair is 0 0643 ft/ft The site-specific vertical groundwater gradient for the MW-2X/MW-202 pair is 0 0007 ft/ft The historically positive vertical groundwater gradients do not suggest downward movement of contaminants between different zones Vertical groundwater gradient calculations have ' been performed at regular intervals since August 25, 1997 2.0 GROUNDWATER MONITORING 2.1 Groundwater Sampling Procedure—Monitoring Wells ' On July 20, 2005, Del-Tech Geotechnical Support (Del-Tech) 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 Stagnant water in the well casing was purged using a Honda® centrifugal pump or a ' Waterra® pump with dedicated tubing as recorded in the field logs (Appendix C) The rate of well purging was monitored The wells were purged of at least three casing volumes or until the groundwater parameters (temperature, conductivity, and pH) had stabilized (Appendix C) indicating that water representative of actual aquifer conditions was entering