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Chevron Products Company 7 Former Chevron Service Station 95775 301 West Kettleman Lane, Lodi, California March 30 2000 remediation system performance at the site This section presents a discussion of the constant -rate aquifer pumping test data analysis and results Data Analysis Following the constant -rate pumping test, graphs of drawdown versus time were produced for pumping and observation wells Graphs were produced for the background phase, pumping phase, and recovery phase of each test Additionally, graphs of changes in barometric pressure dunng background and pumping phase were also produced Data Corrections Various factors that could potentially affect aquifer pumping test data were considered prior to analysis of the data These factors include (1) accuracy, (2) changes in barometric pressure, and, (3) regional fluctuations in groundwater levels 1 To evaluate instrumentation accuracy, manual water level measurements in the monitored wells were collected to verify the electronic data measured by the transducers In general, it was observed that drawdown effects denved from the pressure transducer data and manual data were equivalent 2 Site barometric pressure readings were collected simultaneously with electronic water level readings on a separate data -logger used during the constant -rate pumping test . Barometric pressure was compared to background phase data to evaluate the effects of changing barometnc pressure on water levels Barometric pressure changes dunng the pumping phase were compared to drawdown data to determine if barometric pressure changes during constant -rate pumping test significantly affected water levels in observation wells • Based on G -R's continuous monitoring conducted in October 1999, SECOR assumed that operation of the Well 12 would result in water level fluctuations at the site In addition, rainfall also occurred dunng the time penod that background data was collected Leaching of rainfall into the aquifer would also result in groundwater fluctuations not related to barometric pressure As a result, SECOR utilized data collected from the morning of November 19th through 6 00 a m on November 20'h to evaluate barometric pressure influences This period was selected because no precipitation occurred days prior to or dunng this time and Well 12 did not operate for approximately 10 hours pnor to or dunng this period Operating periods and discharge quantities of Well 12 from November 14th through November 28th are summanzed on Table 1 Based on this, background data collected dunng this period was considered to be most reliable for evaluating barometric pressure influences 11Chevron1957751Aquifer test\Revised195775Aquifertestrevised doc