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AMBRIA were conducted in September, October, and December 2003 For each event, groundwater was extracted continuously from well MW-4 for 5 days Each event is discussed in detail below Personnel Present Cambria project engineer Curtis Payne or technician Dayton Busch conducted the field activities, working under the supervision of Senior Project Engineer Dan Leseure September 2003 GWE Event Cambria conducted the first batch GWE event on well MW-4 from September 8 through 12, 2003 GWE settings were established based on results of the October 2002 aquifer pump test Groundwater was extracted using a 2-inch diameter Grundfos electric submersible pump The pump was set approximately 6 inches above the bottom of the well The extracted groundwater was temporarily stored in an onsite storage tank and transported via vacuum truck to the Martinez Refining Company in Martinez, California for recycling The following parameters were monitored during extraction duration, flow rate, volume, drawdown, and recharge A totalizing flow meter was used to monitor the flow rate and number of gallons pumped during the tests Pressure head measurements were collected from wells MW-3, MW-4, and MW-7, and piezometers P-1 and P-2 using MiniTrol]TM pressure transducers Water levels were also checked manually with an electronic water level indicator from these wells and other wells Barometric pressure readings were also collected Samples were collected periodically from the extracted groundwater stream during the test and retained in vials containing hydrochloric acid preservative with no head space These samples were labeled, entered onto a chain-of-custody record, and placed into a cooler with ice for transport to a state of California certified laboratory for analyses The samples were analyzed for TPHg, BTEX, MTBE, TBA, di-isopropyl ether, TAME, and ETBE by EPA Method 8260B A total of 5,429 gallons of groundwater were extracted from MW-4 over 5,783 minutes (96 4 hours) The flow rate averaged 0 94 gallons per minute (gpm) Table i presents the pump test extraction data, analytical results of groundwater samples, and mass removal data Approximately 1 5 pounds of MTBE were removed during this event The initial groundwater sample collected from MW-4 on September 8 contained 13,000 ppb MTBE and 120,000 ppb TBA Subsequent groundwater samples collected from MW-4 on • September 9, 10, 11, and 12 contained MTBE at 34,000 ppb, 43,000 ppb, 31,000 ppb, and 30,000 ppb, respectively These groundwater samples also contained TBA at 64,000 ppb, 0955 5