ARCHIVED REPORTS XR0011458 - Laserfiche WebLink

Home Browse Search

Geological Technics Inc Page 5 ' Groundwater Momtornng Report Project No 425 2 Apn127,2006 Zone C ' The average groundwater elevation in Zone C for the January 2006 monitoring event was 73 50 feet AMSL This represents a decrease of 0 41 feet since the October 2005 monitoring event Groundwater bearing and slope average N70°W and 0 0200 ft/ft, respectively ' Bearing is suspect due to the linear positions of MW-101, MW-102, and MW-201 The groundwater contour map (Figure 7) suggests the groundwater bearing is in a north ' northwesterly direction Table 4 summanzes the groundwater data from the Zone C Figure 7 shows the groundwater gradients for January 22, 2006 groundwater monitoring event Zone D ' The groundwater elevation in Zone D is 74 23 feet AMSL This represents a decrease of 0 47 feet from the October 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 M 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 January 22, 2006 monitoring event for the MW-2/MW-2X pair is 0 0574 ft/ft The site- specific vertical groundwater gradient for the MW-2X/NM-202 pair is 0 0093 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 1 ' 2.0 GROUNDWATER MONITORING 2.1 Groundwater Sampling Procedure—Monitoring Wells ' On January 22, 2006, Del-Tech Geotechnical Support (Del-Tech) personnel amved 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® inertia 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