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Canepa's Car Wash 6230 Pacific Avenue, Stockton, California January 31, 1995 Groundwater Pump Test Page. 3 The actual pumping rate during the test was measured several tunes at 4 67 gpm Pumping began at 09 23 and ended at 21 17, a total of 714 uninterrupted rrunutes Recovery measurements continued on the observation wells for 700 minutes The field note time sheets for each well are included as Appendix A Elevations for the water table before and after the ' test are shown in Table 1 4.0 Aquifer Hydraulic Properties Tune-Drawdown curves using the Jacob Straight-Line Method (in "Ground Water and ' Wells", (1972), Johnson Division, Universal Oil Products Co) and Residual-Drawdown curves were prepared for each observation well (Appendix B & C, respectively) Calculations based on the data plots of Appendices A & B are summarized as Tables 2 & 3, ' respectively A Distance-Drawdown curve was also plotted from the four observation well data(Appendix D) 4.1 Time-Drmvdown The aquifer properties from the pumping portion of the test (714 minutes) are listed below and averaged The individual plots with calculations are Appendix B Average of MW-1 MW-4 MW--6 MW-7 MW-8 Observation Wells MW-4 6, 7& 8 T 1,490 9,000 13,300 11,700 27,400 15,400 gpd/ft S — 00025 00021 0 0613 0 0039 00028 where T=264 Q/ds(gpd/ft) ' Q=pumping rate, in gpm ds= slope of the time-drawdown graph expressed as the change in drawdown between any two values of time on the log scale ' whose ratio is 10 S =0 3 Tto/r2 to=mtercept of the straight-line at zero drawdown, in days ' r=distance, in feet, from pumped well to observation well where drawdown measurements were made A visual analysis of the plots show penods of equilibrium (when the plot is horizontal there is no additional drawdown with tune) and boundary effects (where the plot steepens because of increased drawdown)