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ATC Associates,Inc Project No 99975 7501 ' 4 0 REMEDIATION STATUS AND EFFECTIVENESS REPORT Soil vapor extraction(SVE)and groundwater extraction at the site began on February 10, 1994 ' Since that time,through July 1999 more than 5 4 million gallons of groundwater and 53 million cubic feet of soil vapor have been extracted from four soil vapor and groundwater co-extraction wells at the site. Prior to discharge to the atmosphere and surface, the soil vapor and groundwater are treated through 2,000-pound vapor phase and aqueous phase carbon units, respectively A log of groundwater production is presented in Table 4 and the groundwater influent and effluent analyses are presented in Table 5 Table b is a log of the production and ' analysis of extracted soil vapor The data which are most significant for assessing the progress 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 for samples collected during the three monitoring events prior to the startup of ' the remediation program (in February 1998) with the average results for the three most recent monitoring events These results near show near total elimination of total hydrocarbons inmost ' of the previously impacted monitoring wells, and reductions of 87-95 percent in the severely impacted monitoring wells BEI-MW3 and BEI-MW 1 Reductions of benzene in these wells are more than 95 percent and 99 percent,respectively The anomalous high TPHg concentration in monitoring well BEI-MW3 detected in March 1999 at 17,000 ug/l fell to 5,300 ug/1 for the July event Figures 5 through 8 illustrate the decline in TPHg and benzene concentrations over the remediation period for monitoring wells BEI-MW3 and BEI-MWI, respectively ' A significant observation,regarding the remediation process has been the considerable amount of bio-mass evident in the groundwater immediately after its extraction This was particularly ' apparent during the initial months after the remediation program was initiated This occurrence provided evidence that the physical and chemical characteristics for bio-degradation in the groundwater both above and below the surface, are particularly favorable ATC believes the ' migration of fresh oxygenated air and water through the site as a result of the soil vapor and groundwater extraction has effected the removal of far greater amounts of hydrocarbons,by the ' process of enhanced bio-degradation, than have been recovered above ground in the respective SVE and groundwater carbon treatment units In recent months the amount of bio-mass produced has declined to negligible amounts, which is evidently the result of rapidly declining ' amounts of hydrocarbon concentrations SVE Radius of Influence Testing During the December 10, 1998 monitoring event,a soil vapor extraction radius of influence test - was conducted to determine the vacuum influence surrounding the co-extraction well EW-1 As soil vapor was extracted from EW-1, the vacuum influence away from the well was measured at three surrounding monitoring wells While pumping 100 cubic feet per minute from EW-1 the vacuum in the extraction well is only about 3 inches of mercury (39 inches of water) This Groundwater Monitoring and Rernediation Status Report Page 3