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� v <br /> 0 <br /> 1 <br /> ASSOCIATES I NC: <br /> One groundwater sample was collected from each boring at the depth groundwater was first <br /> encountered Petroleum hydrocarbons or fuel oxygenates were not detected in the <br /> ' groundwater samples Results are summarized in ATC's Summary Report of Supplemental <br /> Subsurface Investigation, dated January 4, 2002 <br /> 3.3 Remediation Activities <br /> Aquifer Pump Test <br /> On July 16, 17, and 18, 2002, an aquifer test was conducted over a 48-hour period by extracting <br /> groundwater at a generally constant rate from well MW1 Wells MW2 and MW3 were used as <br /> observation wells during the aquifer pump test The test was performed to determine aquifer <br /> properties and the radius of influence (ROI) for groundwater pumping The groundwater <br /> ' extraction pilot test yielded a pumping rate of approximately 4 76 gallons per minute (gpm) and a <br /> ROI of up to 85 feet Results are summarized in ATC's Feasibility Study Report, dated <br /> December 12, 2002 <br /> ' Groundwater Extraction <br /> From July 2003 to December 2003, ATC conducted periodic groundwater extraction by pumping <br /> groundwater from well MW 1 and discharging the groundwater into the City of Ripon sanitary <br /> sewer Eleven groundwater extraction events were conducted from July 8 to December 4, 2003 <br /> ' Each extraction event ranged from 13 to 16 hours in duration A total of approximately 50,060 <br /> gallons of groundwater was extracted and discharged to the City of Ripon sanitary sewer <br /> Groundwater samples were collected at the beginning and end of each extraction event The <br /> ' samples were shipped under chain of custody to state certified Argon Laboratories ELAP#2359 <br /> and analyzed for Total Petroleum Hydrocarbons as gasoline (TPHg) utilizing EPA Method <br /> 801513, benzene, toluene, ethylbenzene, and total xylenes (BTEX) constituents utilizing EPA <br /> ' Method 8021B, and methyl tert-butyl ether (MTBE), ethyl tertiary butyl ether (ETBE), tertiary <br /> butyl alcohol (TBA), tertiary amyl ether (TAME), di-isopropyl ether (DIPS), 1,2-dichloroethane <br /> ' (1,2-DCA), and ethyl dibromide (EDB) utilizing EPA Method 8260B <br /> 4.0 EXISTING CONDMONS <br /> ' 4.1 Sod Conditions <br /> ' 41 1 Site GeoloRy <br /> Geologic materials encountered beneath the site during previous drilling activities consisted of <br /> ' silty clays (CL), sandy silts (ML), silty sands and slit/sand mixtures (SM), poorly-graded sands <br /> (SP), and well-graded sands (SW) <br /> w 114981tirepoiU\ciosure doc 3 <br /> 1 <br />