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. 06 September 2002 AGE Project No 95-0130 Page 2 of 4 permeable to semi-permeable lithology located between 35 and 55 feet bsg at the site and based on AGE's previous experience with aquifer characterization at sites with similar lithology Hydrogeologic Unit No 1 (located between 30 and 55 feet bsg) was defined in Multi-level Monitoring Well Installation Report-3rd Quarter 2001 and will be utilized to represent the aquifer thickness (B) Ground water modeling for capture zone assumes an X-axis parallel to the ground water flow direction and a Y-axis perpendicular to the X-axis through the pumping well Positive "X" values extend upgradient and negative X extend down gradient Assuming that 1) a steady state condition could be achieved at the site during ground water extraction, 2) the extraction well fully penetrated a confined aquifer, 3) horizontal flow of ground water was uniform prior to pumping and that no water enters the aquifer at the base,4)there was no dispersion - all contaminants travel on the stream lines, and 5) the aquifer is isotropic Then Q =the pumping rate = 5 GPM = 962 5 ft3/day K=hydraulic conductivity= 10-2 cm/s =28 35 ft/day b = aquifer thickness = 25 ft i =hydraulic gradient = 0 004 ft/ft u = ground water velocity=Ki = 28 35 ft/day x 0 004= 0 1134 ft/day The following equation was utilized to give the maximum half width(YL) of the capture zone at an infinite distance in the upgradient direction from the extraction well,the point was calculated using YL = f Q —2bu = f 962 5 ft3/day— 2(25 ft)(0 1134 ft/day) YL = f 170 ft The stagnation point, XL, in the negative x direction with y= 0, is the downgradient extent of the capture zone The point was calculated using XL — Q — (2 7t bu) 9625 ft3/day— 2 n(25 ft)(0 1134 ft/day) XL = 54 ft Advanced GeoEnvironmental,Inc