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<br />90 GROUNDWATER PUMPING TESTS <br /> <br />CASE STUDIES 91 <br /> <br />The Rho = 1 type curve for model 2 (Figure F.3 in Appen. <br />dix F) wa$ matched to the time-recovery logarithmic graph, <br />and aquifer tran$missivity and storativity were calculated <br />to be 74 gpdlft and 1.03xlO''. respectively. Well storage <br />capacity impacts were appreciable during the entire pump- <br />ing period. Calculations for. the production well are as fol- <br />lows: <br /> <br />Q = 9 gpm, rw = 0.219 it <br /> <br />Match Pt. Coord. W(u,S,Rho) = 1.0. 1/u = 10" <br />s = 14 it t = 18 min <br /> <br />T = 1.146 X 10'(9)1.0/14 T = 73.7 gpdlft <br /> <br />S = 73.7(18)/[2.693 X 103(4.78 X 10")105] S = 1.03 X 10-4 <br /> <br />Table 5.4. Database for Case Study 5.4 <br /> <br />Time After Weill <br />Pumping Started Adjusted Drawdown <br />(min) (ftl <br /> <br />5 0.76 <br />28 3.30 <br />41 3.59 <br />60 4.08 <br />75 4.39 <br />244 5.47 <br />493 5.96 <br />669 6.11 <br />958 6.27 <br />1129 6.40 <br />1185 6.42 <br /> <br />The time-recovery graph for the production well is pre- <br />sented in Figure 5.4. <br /> <br />LEAKY ARTESIAN AQUIFER SYSTEM <br /> <br />O. I I 10 100 <br />Time After Pumping Stopped <br />Figure 5.4. Time-recove~y grapb for Case Study 5.3. <br /> <br />1000 <br />Oli n) <br /> <br />A pumping test was conducted in Case Study 5.4 on July <br />2 and 3, 1951, using a group of fully penetrating wells <br />located about 1 mile southwest of the corporate limits of <br />the village of Dietrich, Illinois (see Walton, 1962, pp. <br />31-33). In general, 22 ft of sandy clay overlie an 8-ft-thick <br />fine sand and some gravel aquifer which is underlain by <br />shale. The thickness of the aquitard is 14 ft. There are no <br />nearby interfering production wells or aquifer boundaries. <br />The effects of discharging a production well were measured <br />in three observation wells. Observation well 1 was located <br />96 ft northwest of the production well, observation well 2 <br />was located 92 ft southwest of the production well, and <br />observation well 3 was located 245 ft northeast of the <br />production well. Pumping was started at 2:10 p.m. on July <br />2 and was continued for a period of 20 hours at a constant <br />rate of 25 gpm until 10:00 a.m. on July 3. Time-drawdown <br />data for observation well 1 are presented in Table 5.4. <br />The time-drawdown curves for the observation wells <br />were matched to appropriate model 3 type curves <br />(Figure F.4 in Appendix Fl. and match point coordinates <br /> <br />1000 <br /> <br />ProductIon W..]] <br /> <br />.... 100 <br />LL <br />>- <br />L <br /><II <br />> <br />o <br />u <br /><II <br />Q:: <br /> <br />10 <br /> <br /> <br />.. <br /> <br />I <br />