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1 <br /> GeoHydrologic Consultants, Inc <br /> . 6.2 Collection of Groundwater Samples <br /> 1 Groundwater samples were collected at the beginning and at the completion of the 12- <br /> hour pumping tests from wells EW-5D and EW-5S The groundwater samples were <br /> collected from the discharge hose into laboratory supplied bottles and placed on ice for <br /> delivery to the laboratory for analysis The groundwater samples were delivered the next <br /> day to Associated Labs of Orange, California, which is certified by the State of California <br />' for the test methods performed, under strict chain of custody protocol The samples were <br /> analyzed for TPHg using EPA Method 8015 modified and BTEX, MTBE, and other <br /> oxygenates including ETBE, DIPS, TBA, and TAME by EPA Method 8260B <br /> Groundwater analysis on the EW-5D samples indicated TPHg concentrations of 67,600 <br /> gg/L at the start of the test and 96,900 gg/L at the end of the test, benzene concentrations <br /> of 2,950 gg/L at the start of the test and 5,340 µg/L at the end of the test, while MTBE <br /> concentrations were below the MDL (0 18 gg/L) Based on these analytical results and <br /> the volume of water extracted (approximately 1,400 gallons) approximately 0 748 pounds <br />' of TPHg was removed during the test, and the mass removal rate was estimated to be <br /> approximately 1 496 pounds of TPHg per day <br />' Groundwater analysis on the EW-5S samples indicated TPHg concentrations of 85,900 <br /> gg/L at the start of the test and 99,500 gg/L at the end of the test, benzene concentrations <br /> of 14,400 gg/L at the start of the test and 17,300 gg/L at the end of the test, and MTBE <br />'. concentrations of 3,420 gg/L at the start of the test and 4,430 gg/L at the end of the test <br /> Based on these analytical results and the volume of water extracted (approximately 135 <br /> gallons) approximately 0 163 pounds of TPHg was removed during the test, and the mass <br />' removal rate was estimated to be approximately 0 326 pounds of TPHg per day <br /> Analytical results are summarized in Table 9 A copy of the laboratory report and chain- <br /> of-custody documentation is included in Appendix F <br />' 7.0 PUMPING TEST RESULTS <br />' 7.1 Analytical Methods <br /> The pumping test data from the test of EW-5D were analyzed using the Jacob Method <br />' (Cooper and Jacob, 1946) Drawdown data for the extraction well (EW-513) and <br /> observation wells (TB-7 and TB-10) were plotted on a semi-log axis with time (minutes) <br /> versus drawdown (feet) (Figures 6A, 6B, and 6C) <br /> Drawdown data for extraction well EW-5S were plotted on a semi-log axis with time <br /> (minutes) versus drawdown (feet) (Figures 7A) For the pump test on EW-5S, the <br /> recovery of the pumping well was analyzed using the Jacob Method (Cooper and Jacob, <br /> 1946) Recovery data were plotted on a semi-log axis with time (minutes) versus <br /> . corrective recovery(Tt/ta) for the pumping well EW-5S (Figure 7B) Measurable <br /> drawdown was not observed in any of the observation wells, but rather water levels <br /> TOC 171 Pilot Study Page 17 <br />