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Gea/ogkal TecluiusInc Page 4 Groundwater Monitoring Report Project No 989 2 October 4,2004 ' 1.3.3 Average Groundwater Velocity Hydraulic conductivity and porosity were calculated from three soil samples collected during ' the installation of MW-101 in March 2003 The laboratory results are included in Appendix C ' The average hydraulic conductivity (K) value, estimated from the sample collected at 21-feet bgs is 6 87E-07 centimeters per second (cm/sec), and the average hydraulic gradient (i) across the site is approximately 0 0065 Based on the equation v = K i/n, where n is effective porosity averaging 0 3917, the average horizontal groundwater velocity (v) at this depth is estimated to be 0 012-feet per year(ft/yr) ' The average hydraulic conductivity (K) value, estimated from the sample collected at 26-feet bgs is 1 17E-07 centimeters per second(cm/sec), and the average hydraulic gradient(i) across the site is approximately 0 0065 Based on the equation v = K i/n, where n is effective ' porosity averaging 0 3811, the average honzontal groundwater velocity (v) at this depth is estimated to be 0 002 ft/yr The average hydraulic conductivity (K) value, estimated from the sample collected at 41-feet bgs is 6 28E-07 centimeters per second(cm/sec), and the average hydraulic gradient(i) across the site is approximately 0 0065 Based on the equation v = K i/n, where n is effective porosity averaging 0 4238, the average horizontal groundwater velocity (v) at this depth is estimated to be 0 01 ft/yr I t 2.0 GROUNDWATER MONITORING 2.1 Groundwater Sampling ' On July 15, 2004, Del-Tech Geotechnical Support Service personnel arrived on-site, opened the wells and measured the depth to water with an electrically actuated sounding tape The water level reading was recorded to an accuracy of 0 01 foot If free-floating product had ' been suspected, a clear disposable bailer would have been used to gauge the interface No floating product was observed during this sampling event ' Stagnant water in the well casing was purged using a centrifugal pump with dedicated tubing The rate of well purging was monitored The wells were purged of at least three casing volumes and until the groundwater parameters (temperature, conductivity and pH) had ' stabilized (Appendix B) indicating that water representative of actual aquifer conditions was entering the well Groundwater parameter stabilization was characterized by three successive ' readings within 10% All water removed from the monitoring well and not used as a sample was placed into a 55- gallon DOT approved container that was properly labeled and temporarily stored on-site 1 '