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Y' •... 2.2 Groundwater Gradient and Direction Groundwater elevations have been recorded at each well since April of 1990. Tabulated data and hydrographs are provided in Appendix A. Water table elevations were not recorded in MW-2 and MW-4A after July of 1993 due to the installation of recirculating pumps installed for bioremediation activities. The groundwater gradient is variable across the site. South of MW-6 the gradient is generally to the north-northwest and northwest with a magnitude ranging from 0.001 to 0.006 and direction varying through 43 degrees. North of MW-6 the gradient is an order of magnitude less than in the area to the south, values range from 0.0003 to 0.0009 and directions vary through 107 degrees. Gradient directions and magnitudes are shown on figure 2. Table 1. Gradient Calculated From Wells Using 1993 and 1995 Data Well Triplets Used Gradient Slopes by Year 1993_ 1995 South of MW-1, MW-3, MW-5 0.002 0.006 MW-6 MW-1, MW-5, MW-6 0.002 0.002 MW-2, MW-5, MW-6 0.003 0.001 North of MW-3, MW-5, MW-7 0.0009 0.0009 MW-6 MW-5, MW-6, MW-7 0.0003 0.0003 2.3 Linear Groundwater Velocity and /aquifer Flow Dischame 71re linear velocity of groundwater beneath the site is estimated from the water table gradient and the aquifer properties in two areas. South of MW-6 groundwater flow velocity is estimated at 15.8 ft/yr in a northwesterly direction, and north of MW-6 it is 4.7 fl/yr in variable directions. 'irtre flow discharge front the aquifer beneath the site is 2.2 acre-feet per year (1.3 gpm). Assumptions and calculations used to estimate these parameters are described below. 'i1ie linear groundwater velocity can be estimated in the direction of decreasing water table elevations in a homogeneous hydraulic conductivity field using the following equation. dl l I V = KdLn (1) V = velocity of groundwater now K = saturated hydraulic conductivity diI = pressure head gradient dl, n = porosity L.� 4 CONDOR