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Canepa's Car Wash 6230 Pacific Avenue Stockton, California January 31, 1995 Groundwater Pump Test Page- 4 i The individual monitoring weUs reacted as follows MW-4 The cone of depression (cone) arrived at 20 minutes, equilibrium was reached between 50 and 95 minutes and a boundary was reached after 500 minutes MW-6 The cone arrived at approximately 12 minutes, a boundary was reached at 46 minutes and equilibrium reached from 90 to 300 minutes Then drawdown continued at the original slope until the pumping stopped MW-7 The cone arrived at approximately 5 minutes, no periods of equilibrium were encountered, and a boundary was reached at 480 minutes MW-8 The cone arrived at approximately 24 minutes, equilibrium reached from 31 to 50 rrunutes, drawdown from 50 to 94 minutes, equilibrium again from 94 to 300 minutes and drawdown continuing to the end of pumping The value of T has been affected by both recharge to the aquifer and impermeable boundary affects These seem to have canceled each other, because the T values from the distance-drawdown plots has proven to be reliable regardless of the recharge effect The T-values were identical (1,490 gpd/ft) from both the Time-Drawdown and Distance-Drawdown calculations 42 Residual-Drawdown Transmissibility values calculated from the recovery portion of the pump test (-700 minutes) are summarized below and averaged The individual plots with calculations are Appendix C The T value average during the recovery period is approximately one-half(52%) of the time-drawdown value Average of MW-1 MW-4 MW-6 MW-7 MW-8 Ohservation Wells 7& 8 F-T -- 11,400 8,800 5,300 8,800 8,600 where T=264 Q/ds', (gpd/ft) Q=pumping rate, in gpm ds'= slope of the residual-drawdown graph expressed as the change in residual drawdown per logarithmic cycle of values of t/t' t=time, in minutes, since pump test started V=time, in minutes, since pump stopped