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Chevron Products Company 6 Farmer Chevron Service Station 95775, 301 West Kettleman Lane, Lodi, California March 30, 2000 • • Recovery Phase — The period of time Immediately following cessation of the pumping period during which the water levels in the aquifer recover to nearly static, non -pumping levels The rate of recovery of water levels with time, since cessation of pumping, provides Important data for analysis of hydraulic characteristics Background Phase Background water levels were monitored in all the observation wells for approximately 8 - days prior to start of pumping Due to a vacuum formation in MW-14/EX-2, data recorded from November 14 to 18, 2000, background (or baseline) data collected was determined to be anomalous and therefore discarded Following the termination of the step -drawdown test, background water level data was recorded from November 18 to 22, 2000, for a duration of approximately 90 -hours Background water level graphs for wells MW -1, MW-14/EX-2, EX -3, MW -5A, MW -5B, MW -8A, and MW -8B are presented as Figures 3 through 9 Pump Phase The constant rate pump test was conducted between November 22 and 27, 2000, using extraction well EX -3 EX -3 was pumped at a sustainable rate of approximately 9 0 gpm for 118 -hours The pumping rate of 9 0 gpm provided approximately 8 5 feet of an available 22 feet of drawdown Dunng the pumping test, water level measurements were collected using . data -loggers in the selected observation wells Drawdown data from the observation wells were used to provide estimates of T and S for the aquifer Instantaneous flow rate and total flow volume were periodically recorded during the test Manual water level data for the observation and pumping wells were collected periodically using an electric sounder to venfy accuracy of the pressure transducers • Recovery Phase On November 28, 2000, after completion of the pumping test, recovery data was monitored until water levels recovered to at least 95 percent of the pre -pumping levels Dunng the recovery phase, the transducers were not moved and the data -loggers were configured to record data at a logarithmic rate similar to the rate used during the pumping test Once the recovery phase of the test was completed, the data was downloaded from the data -loggers onto to a portable computer for analysis DRAWDOWN DATA ANALYSIS AND RESULTS The purpose of the constant -rate aquifer pumping tests was to monitor the aquifer's response to pumping, and to use the data to estimate aquifer parameters including T and S Estimates of the aquifer parameters were then used to validate the current groundwater extraction and I \Chevron1957751Aqutfer test\Revtsed195775Aquifertestrevised doc