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w <br /> h <br /> Chapter six Groundwater remediation 189 <br /> r <br /> 1 366[(200)(0 0410)}(10�2-12 22) <br /> [(0 15)(1440)]_ -->rR, =isl m <br /> log(3/rR,) <br /> Dzscusszon <br /> 1 In Eq VI i for confined aquifers, the "ht -h2" term can be replaced <br /> by "s2 - sl," where sz and $2 are the drawdown values at rz and r2, 4" <br /> respectively However,no analogy can be made here, that is, "h2-hl" <br /> in Eq VI 12 cannot be replaced by "sz-s2 <br /> 2 The differences In the calculated r,u values in (b) come mainly from <br /> the unit conversions and data truncations <br /> 1" •i�,,w^y rte'r.n iv i.. <br /> Example VI 1 1E Estimate the groundwater extraction rate <br /> of an unconfined aquifer from steady-state `` ' <br /> drawdown data <br /> se the following information to estimate the groundwater extraction rate a -M Fsx� ris �a <br /> a pumping well it an unconfined aquifer- <br /> Aquifer <br /> quifer Aquifer thickness =30 0 ft (91 m) thick <br /> Well diameter =4-m (01 m) diameter <br /> Well perforation depth = full penetrating <br /> Hydraulic conductivity of the aquifer =400 gpd/ft2 <br /> Steady-state drawdown= 2 0 ft observed in a monitoring well 5 ft from <br /> the pumping well = 12 ft observed in a morutormg well 20 ft from _ <br /> the pumping well <br /> Solutions sus f Y k <br /> a Fust we need to determine <br /> h, and h2 <br /> S k <br /> h = 300-20 = 280ft `" '"� <br /> h2 = 300 - 12 = 28.8 ft <br /> b Inserting the data into Eq VI 12, we obtain ` r�" <br /> 4 <br /> �3�K1E V���� �c w ✓ <br /> __ K(hi-h2) _ 400(2882-2802) �r ,"� <br /> Q 10551og(r2/r,) _ 10551og{20/5} -28 6 gpm <br /> .. `� <br /> VI 12 Capture zone analysis <br /> ift <br /> r 4kt <br /> e key element in design of a groundwater extraction system is selection <br /> proper locations for the pumping wells If only one well is used, the well <br />