A pumping test was carried out to determine the average hydraulic conductivity of a sand deposit 20 m thick overlying impermeable clay. The discharge from the pumping well was 10 × 10-3 m3 /s. Drawdowns in the observation wells located 15 m and 30 m from the centerline of the pumping well were 2.1 m and 1.6 m, respectively. Groundwater table was reached at 3.2 m below the ground surface. Determine the hydraulic conductivity of the sand. Estimate the effective grain size using Hazen's equation.