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A S S O C I A T E S I N C two-Inch monitoring wells One soil sample from each boring was collected and after the groundwater monitoring wells were developed one groundwater sample was collected from each ' well Soil and groundwater samples contained detectable concentrations of petroleum hydrocarbons Results are summarized In ATC's Summary Report of Additional Subsurface Investigation, dated June 1, 1999 On September I2, 2001, and October 4 and 5, 2001, a geologist from ATC supervised the advancement of six soil borings, SB7 through SB 12, to approximately 20 to 25 feet bgs and one cone ' penetration test (CPT) boring to approximately 45 feet bgs Analytical results of soil samples Indicated no detectable presence of petroleum hydrocarbons or fuel oxygenates One groundwater sample was collected from each boring at the depth groundwater was first encountered Groundwater samples indicated no detectable presence of petroleum hydrocarbons or fuel oxygenates Results are summarized in ATC's Summary Report of Supplemental Subsurface Investigation, dated January 4, 2002 ' On July 16, 17, and 18, 2002, an aquifer test was conducted over a 48-hour period by extracting groundwater at a generally constant rate from well MW 1 The test was performed to determine the ' aquifer properties and the radius of influence (ROI) for groundwater pumping The groundwater extraction pilot test yielded a pumping rate of approximately 4 76 gpm and a ROI of up to 85 feet Results are summarized in ATC's Feasibility Study Report, dated December 12, 2002 GROUNDWATER EXTRACTION ACTIVITIES ' Eleven groundwater extraction events were conducted approximately every two weeks from July 8 to December 4, 2003 Prior to extracting groundwater, ATC personnel measured the depth to water in the three site monitoring wells at the start of each groundwater extraction event A submersible pump equipped with a flow meter and a discharge hose was placed in MW1 and the extracted groundwater was discharged to the City of Ripon sanitary sewer system Groundwater was extracted for an average of approximately 15 hours during each event, resulting in a total of approximately 50,060 gallons of groundwater extracted from MW 1 A groundwater sample was collected from MW 1 at the ' beginning and dust prior to completion of groundwater extraction during each event The groundwater samples were placed in an Ice chilled cooler and submitted to State-certified Argon Laboratories (ELAP Cert No 2359) for chemical analyses of total petroleum hydrocarbons as ' gasoline (TPHg) utilizing EPA Method 8015B, benzene, toluene, ethylbenzene, xylenes (BTEX) utilizing EPA Method 8021B, and methyl tert-butyl ether (MTBE), ethyl tertiary butyl ether (ETBE), tertiary butyl alcohol (TBA), tertiary amyl ether (TAME), di-Isopropyl ether (DIPE), 1,2- ' dichloroethane (1,2-DCA), and ethyl dibromide (EDB) utilizing EPA Method 8260B Analytical Results Benzene was detected in the groundwater samples collected from MWI in 4 of the I1g roundwater extraction events at concentrations ranging from 5 9 to 17 micrograms per liter (µg/L) Toluene was detected in 10 of the I 1 groundwater extraction events at concentrations ranging from 0 7 to 5 5 µg/L Ethyl benzene was detected in all of the groundwater extraction events at concentrations ranging from 18 to 63 ltg/L Xylenes were detected in all of the groundwater extraction events at concentrations ranging from 5 0 to 25 µg/L TPHg was detected In all of the groundwater extraction events at concentrations ranging from 1,400 to 2,700 ltg/L MTBE, ETBE, TBA, TAME, D1PE, 1,2- s lenvironmenta11149811Reports14Q12-03 doc 2 s