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therefore calculated using data from the slug extraction portion of each test. The data plot for the M1,7-6 test was not considered representative of aquifer conditions due to inconsistencies in the data. Hydraulic conductivity calculations were therefore based on data from the MW-1 and MW-3 slug extraction. tests. A hydraulic conductivity of 195,0 gallons per day per square foot (gpd/ft2) was calculated for MW-1. Monitor Well 3 calculations indicate a 224 gpd/ftz hydraulic conductivity. Averaging these values yields a generalized site hydraulic conductivity of 209.50 gpd/ftz. Groundwater Extraction Several groundwater extraction options, including ono-well, two-well, and three-well pumping scenarios, have been evaluated for use in the proposed groundwater remediation at the site. This evaluation included combining various extraction well locations with various pumping rates. Projected zones of capture for each combined pumping scenario were produced to estimate the duration of groundwater treatment associated with each alternative. Based on these evaluations, the estimated lateral extent of - groundwater contamination shown on Figure 3, and the estimated hydraulic conductivity of the subsurface materials derived from the slug tests described above, a one-well pumpirs scenario has been selected for this. remedial action plan. The location of the proposed extraction well (EW-1) and the projected zone of capture of the dissolved chemical plume with a pumping rate of 8 gallons per minute (gpm) are shown on Figure 9. With a pumping rate of S gpm, groundwater extraction at EW-1 will provide control within a zone of influence extending approximately 50 feet downgradient (southwest) of the extraction well. Since chemicals have not been reparted in y concentrations above laboratory detection limits at MW-9 or -10, this zone of influence will be adequate for control of groundwater containing chemicals at the site. To achieve cleanup of groundwater to below DHS Action Levels, as presented in the site assessment report, it is estimated that a minimum of five pore volumes of groundwater from within the chemical plume must be exchanged. Exchange is accomplished by continuous - operation of the extraction, treatment and infiltration system. Groundwater velocity at the site has been estimated to be approximately 122 feet per year. Groundwater moving at a velocity of 122 feet per year from the extreme northeastern edge of the estimated contaminant plume would take approximately 1.04 years to reach EW-1. Therefore, the estimated duration of groundwater treatment activities at this site using a single extraction point is expected to be approximately 5 years. A more accurate estimate of the duration of treatment activities can be made once the system is started and data is acquired on actual rates of contaminant --- — -- ---concentration-reduction - 18