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ATC Associates Inc Project No 99975 7501 The locations of the groundwater monitoring wells and other relevant features are shown on Figure 2 Table 1 summarizes the construction details for all monitoring and co-extraction wells installed for site investigation, groundwater monitoring and site remediation 2.1 Analytical Results A summary of all groundwater analytical results to date, including the most recent (and previously unreported)January and June 2000 results and January 2001 results, are presented in Table 2 and are also shown on Figures 3a, 3b, and 3c The results are further discussed under Section 3 2.2 Groundwater Elevations and Gradients A summary of the recent and previous groundwater elevation measurements is shown on Table 3 Groundwater elevation contours for the January 2000, June 2000, and January 2001 results are presented in Figure 4a, 4b, and 4c Copies of the field purge/sampling worksheets are included as Appendix C Historical groundwater elevation data(prior to 5197) and groundwater gradients are included in Appendix D 3 0 REMEDIATION STATUS AND EFFECTIVENESS Soil vapor extraction(SVE)and groundwater extraction at the site began on February 10, 1998 and continued until the system was shut down on February 21, 2000, when the treated water discharge line was removed to accommodate further development of the site It was assumed at that time that further groundwater extraction at the site would either no longer be necessary or if further pumping were necessary, wastewater would have to be discharged into a storm drain under NPDES permitting During the two year duration of the remediation project , nearly 6 3 million gallons of groundwater and 84 million cubic feet of soil vapor have been extracted from ' four soil vapor and groundwater co-extraction wells at the site A log of groundwater production is presented in Table 4 and the groundwater influent and effluent analyses are presented in Table 5 Table 6 is a log of the production and analysis of extracted soil vapor 3 1 Groundwater Analytical Results The data which are most significant for assessing the achievement of the remediation program are the groundwater monitoring results presented in Table 2 and Table 7 For the four most severely impacted monitoring wells, Table 7 presents a comparison of the average TPHg and benzene - concentrations fot sa131lilCs 1,011CLted during the three monitoring events prior to the startup of the remediation program (in February 1998) �,N tth the average results for the three most recent monitoring events These results show near total elimination of total hydrocarbons in most of the previously impacted monitoring wells and reductions of near 93 percent to near 100 percent in the severely impacted monitoring wells BEI-MW3 and BEI-MWI Reductions of benzene in these wells are more than 98 percent and more than 99 percent respectively 2