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CgologicaITecluciCS19C. Page 10 '-' Additional Site Characterization And I"Quarter 2004 Groundwater Monitoring r Project No.425.2 March 22,2004 Intermediate and Deep Wells Depths to groundwater in the intermediate depth monitoring wells averaged 12.57 feet below the top of casing. The average groundwater elevation in the intermediate depth monitoring wells during the January 3, 2004 groundwater-monitoring event was 73.26 feet above mean sea level (AMSL). Site-specific groundwater bearing and slope were calculated using MW-101, MW-105 and MW-106. These wells were chosen because the screen intervals and total depths are �. approximately the same. The site-specific bearing and slope was found to be N70°E @ 0.0037 Mt. These results are consistent with historical groundwater bearing and slope calculations at the site. Groundwater elevation, bearing and slope for the intermediate and deep monitoring wells was calculated from data gathered during the January 2004, monitoring event and the results are summarized in Table 6 of Appendix A. Vertical Groundwater Gradient Vertical groundwater gradients were calculated for the site using the MW-2/MW-102 and MW-102/MW-202 well pairs (Table 7). The site-specific vertical groundwater gradient for the MW-2/MW-102 pair is -0.0047 ft/ft. The site-specific vertical groundwater gradient for the MW-102/MW-202 pair is 0.0249 ft/ft. Both well pairs have been predominantly positive through the site's history. The shallow pair has a number of negative vertical -y gradients while the deep pair is generally, with one exception, positive. The site does not show a trend toward downward contaminant migration between the i. intermediate and deep monitoring wells. There are occasional downward trends between the shallow and intermediate monitoring wells. MW-2 is screened from 5 to 20 feet bgs, MW-102 is screened from 45 to 47.5 feet bgs and 16- MW-202 is screened from 79 to 81.5 feet bgs. Vertical groundwater gradient calculations have been performed at regular intervals since August 25, 1997. 4.0 CONCLUSIONS AND RECOMMENDATIONS �. This investigation was conducted to further define the lateral and vertical extent of petroleum hydrocarbons and other fuel constituents in the soil. The following conclusions have been drawn from the data generated from this site investigation and groundwater monitoring at this site and recommendations for future work: Conclusions 1. Groundwater Gradient L. ❑ The water table groundwater gradient historically flows in a north-northeasterly direction at about 0.0013 ft/ft. ❑ The intermediate depth groundwater typically flows in an easterly direction at about 0.0023 ft/ft. 2. Vertical Groundwater Gradient ❑ Vertical groundwater gradients between the water table and intermediate wells have been found to be flowing upward, during winter and early spring, and downward