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1 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 March 1999 more than 4 4 million gallons of groundwater and 44 ' 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 6 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 monitonng 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 86-90 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 98 percent, respectively Although the TPHg concentration in monitoring well BEI-MW3 at 17,000 ug/l was higher than anticipated,we believe this is a short term condition The extracted groundwater from extraction well EW-1 (see Table 5)shows that benzene in the extracted groundwater is at an all time low and the TPHg concentrations in the influent groundwater is also declining steadily ' A significant observation,regarding the remediation process is 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 provides 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 notably, which we believe is the result of rapidly declining amounts of hydrocarbon ' concentrations SVE Radius of Influence TestLag ' 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-I the vacuum in the extraction well is only about 3 inches of mercury (39 inches of water) This Groundwater Monitoring and Remediation Status Report Page 3 1