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Hydraulic conductivity values calculated from the recovery testing are summarized below. Ff f_rr Well ID Hydraulic Conductivity Flow Velocity ft/yr cm/sec ft/sec MW-1 6.56 x 104 2.15 x 10-' 1.16 MW-2 7.17 x 10-3 2.35 x 10-4 12.72 MW-3 1.14 x 104 3.74 x 10-" 0.20 MW-4 7.94 x 104 2.61 x 10 1.41 MW-5 8.14 x 104 2.67 x 105 1.44 MW-6 7.18 x 10-' 2"36 x 10.5 1.27 MW-8 6.04 x 10' 1.98 x 10"S 1.07 MW-9 8.29 x 10-' 2.72 x 10 1.47 MW-10 2.03 x 10"3 6.66 x 10'' 3.60 MW-11 7.60 x 10"5 2.49 x 10-6 0.13 MW-12 3.32 x 10"3 1.09 x 10-4 5.89 { Geometric 7.79 x 10' 2.55 x 10" 1.38 Mean It is noted that the calculated hydraulic conductivity values reflect the aggregate permeability of the saturated screened interval of a particular well. 6.0 SITE GEOLOGY AND HYDROGEOLOGY Soils encountered while drilling during this and previous investigations generally consisted of sandy silt to silty sand to depths of 14 to 18 feet below grade, underlain by a 0.5- to 2-foot-thick silty clay to clayey silt layer. Below the clay and silt, sand with varying silt content was encountered to the total depth of the borings at 20 to 25 feet below grade. Nearly water-saturated soil was encountered during drilling and sampling at approximately 7 feet below grade,with the depth to groundwater measured in the monitoring wells at approximately 8 feet below grade. Groundwater elevations measured on September 3, 1998 were used to develop the groundwater potentiometric surface map shown on Figure 3. The groundwater gradient as calculated from these measurements is approximately 0.0006 foot per foot in a general southwesterly direction across the site. Seasonal fluctuation of the groundwater table in selected onsite wells is shown on Figure 5. 9