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March 9, 1993 • • <br /> 10433 004 Harding Lawson Associates <br /> Mr. Chuck Kolesar <br /> Page 2 <br /> Well MW-23 was pumped at a constant flow rate of 0.75 gallons per minute(gpm) for a duration of 75 <br /> minutes. Drawdown in the well after this period was approximately 0.90 feet. Well MW-24 was <br /> pumped at a constant flow rate of 0.50 gallons per minute(gpm) for a duration of 97 minutes. <br /> Drawdown in the well after this period was approximately 3.1 feet. <br /> Plates 2 and 3 present the residual drawdown (recovery)curves for wells MW-23 and MW-24, <br /> respectively. The Theis(1935) Method was used to estimate the aquifer transmissivity and hydraulic <br /> conductivity. The Theis Method assumes a homogeneous, isotropic, confined aquifer of uniform <br /> thickness and infinite areal extent. Analysis of the residual drawdown data yield aquifer <br /> transmissivities of 98 feet squared per day for Well MW-23 and 8.0 feet squared per day for Well MW- <br /> 24. Using saturated aquifer thicknesses of 7 and 8 feet for MW-23 and MW-24, respectively, aquifer <br /> hydraulic conductivities of 14 feet per day for Well MW-23 and 1.0 feet per day for Well MW-24 were <br /> calculated. <br /> Performance Assessment <br /> Assessment of the effectiveness of the expanded groundwater extraction system will be performed <br /> following collection of online production data. <br /> Please call me at (415) 899-7367 if you have any questions. <br /> Very Truly Yours, <br /> HARDING LAWSON ASSOCIATES <br /> Larry W. Floyd <br /> Project�Geologist <br /> Daniel J. Craig, R..G. <br /> Senior Hydrogeologist <br /> djc/exwel293 <br /> Attachments: Plate 1 -Well Location Map <br /> Plate 2-Residual Drawdown Over Time, Extraction Well MW-23 <br /> Plate 2 -Residual Drawdown Over Time, Extraction Well MW-24 <br /> Reference: Theis, C.V., 1935. The Relationship Between the Lowering of the Piezometric Surface and <br /> the Rate and Duration of Discharge of a Well Using Ground-Water Storage. American Geophysical <br /> Union Trans., v. 16, p. 519-524. <br />