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'' Geological Teclucirs lnc. Page 4 Groundwater Monitoring Report Project No. 1030.2 March 18,2005 The following conclusions were formed based on the equation: v= K i/n • n =effective porosity ' • K= average hydraulic conductivity • i = average hydraulic gradient (site-specific average is 0.0038 ft/ft) • v = average horizontal groundwater velocity Layer 1 The average hydraulic conductivity (K), estimated from typical K values for silt and clay mixtures (Driscoll, 1986), 0.12 feet per year (ft/yr), and where n is effective porosity estimated at 0.45 (Driscoll, 1986), the average horizontal groundwater velocity(v) of Layer 1 ' is estimated to be approximately 1.0 X 10-3 ft/yr. La er 2 ' The average hydraulic conductivity (K), estimated from typical K values for sand with some fines (Driscoll, 1986), 11.98 to 119.75 ft/yr, and where n is effective porosity estimated at 0.35 (Driscoll, 1986), the average horizontal groundwater velocity (v) of Layer 2 is estimated ' to be approximately 0.13 to 1.30 ftlyr. Layer 3 The average hydraulic conductivity (K), estimated from typical K values for clay (Driscoll, 1986), 0.12 to 0.012 ft/yr, and where n is effective porosity estimated at 0.50 (Driscoll, 1986), the average horizontal groundwater velocity (v) of Layer 2 is estimated to be approximately ' 9.12 X 104 to 9.12 X 10-5 ft/yr. ' 2.0 GROUNDWATER MONITORING 2.1 Groundwater Sampling On January17 2005 , Del-Tech Geotechnical Support Service (Del-Tech) 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 and dedicated tubing. The rate of well purging was monitored. The well was purged of at least three casing ' - volumes until the groundwater parameters (temperature, conductivity and pH) had stabilized ` (Appendix Q indicating that water representative of actual aquifer conditions was entering ' the well. Groundwater parameter stabilization was characterized by three successive readings within 10%. 1