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GeologtralTecknfcslrtc Page 5 ' Groundwater Monitoring Report Project No 425 2 January 31, 2006 Zone C The average groundwater elevation in Zone C for the October 30, 2005 monitoring event was 73 91 feet AMSL This represents an increase of 0 31 feet since the July 20, 2005 monitoring event Groundwater bearing and slope average N67°W and 0 0024 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 north northwesterly direction ' Table 4 summarizes the groundwater data from the Zone C Figure 7 shows the groundwater gradients for October 30, 2005 groundwater monitoring event ' Zone D The groundwater elevation in Zone D is 74 70 feet AMSL This represents an increase of 0 73 feet from the July 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 October 30, 2005 monitoring event for the MW-2/MW-2X pair is 0 0650 ft/ft The site- specific vertical groundwater gradient for the MW-2X/MW-202 pair is 0 0092 ft/ft The historically positive vertical groundwater gradients suggest that no downward movement of contaminants between different zones has occurred 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 October 30, 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 If present, floating ' product and/or sheen are noted below 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 Q. 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 1