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c g: — 202/799-5045 Mr.Michael Rabith page 4 February 6, 1991 the he end of intervals ranging from every 20 seconds at the beginning ofllostto data 5 minutes inut�.at t wells were also The stored data was then downloaded to a personalcomputerelevatin manually monitored before the start of the test and d rI µh course Monitof ring System. Measu the test for water table ements weore and petroleum thickness,using an INTERFACE PRO QP)" of the test and taken approximately every five minutes for the first hour every 3properties.thereafter. ertiesnulos Al water level total duration of the test was ten hours,and was sufficient to determine aqufer p p measurements are Included In Appendix B. 3.2 DATA REDUCTION 3.2.1 Graphical Methods T nor to the pump test to determine the static water table elevations and The monitoring wells were gauged p the hydraulic gradient in the absence of pumping. Figure 2 shows the potentiometric surface poem elevations and groundwater contours measured before the start of the pump test. Table 1 records the static potenti°metric the elevations measured at the end 05 t6) was delayed severalminutes Pump test (cne of dro surface elevations, and from the response of wells screened in the shallow aquifer (MW 2, ps response in the deeper aquifer. This erom the deeper ffect was expected observed inthe a pertaqu ferhe n,the two very l aquifers fare in hydraulic + aquifer. However,based on the drawdown observed P low ground surface is not a continuous confining layer. connection. The clay layer at 25 feet be a region red ter table As a result of pumping from the recovery well, a"conte of depwate tables steeperOcloserto!f earecovery elevation,develops around the pumping well. The slope of the well,and the curve defined by the water table can be represented by a logarithmic function. When plotted on semilog paper(Figure 3),the relationship between drawdown and dista�varying 9 stance from the r il defines pumping a straight line. This line can be extrapolated to predict drawdowns at vary ld be istance drawdown well. The pumping well is typically at a lower elevation than sua measure°�eythe recoverY well efficiency- which ciescy, _ method. The ratio of predicted elevation to actual e which is affected by various energy losses within the vvell and pump. ----Basedon the observed relationship between drawdown and distance from the well (Figure 3), the well -- -— — - efficiency is 56 percent.Transmissivity and storativity determined by the distance-drawdown_m ____ 10,000 gpd/ft and 0.0og (Figure 3). GROUND%%ATE .�+ R ECWNOLOG1•,INC.