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„ ATC Associates Inc 1117 Lone Palmi Avenue, Suite B Q Modesto, California 95351 209-579-2221 F Fax 209-579-2225 A S S o C I A T E 5 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 12 and October 4 and 5, 2001, a geologist from ATC supervised the advancement of six soil bonngs, S137 through SB12, 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 bonng 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 to ATC's Feasibility Study Report, dated December 12, � 2002 Interim remedial action activities consisting of groundwater extraction were conducted at the site from July 8 to December 4, 2003 A total of approximately 50,060 gallons of groundwater were extracted from MW 1 during 11 groundwater extraction events conducted from July 8 to December 4, 2003 Groundwater extraction at monitoring well NMI was conducted in an attempt to reduce petroleum hydrocarbon concentrations in groundwater in the vicinity of MW 1 SAMPLING ACTIVITIES On June 1, 2005, ATC personnel collected groundwater samples from momtonng wells MMI, MW2, and MW3 The locations of the monitoring wells are shown on Figure 2 Prior to collection of groundwater samples, the depth to water was measured to the wells and the, pH, electrical conductivity, and temperature were measured in groundwater purged from the monitoring wells and recorded A minimum volume of three well casings was purged from each well prior to sampling The wells were allowed to recover and samples were collected from each well using disposable bailers The groundwater samples collected from each well were submitted to State-certified Argon Laboratories (Environmental Laboratory Accreditation Program Certification No 2359) for chemical analyses of total petroleum hydrocarbons as gasoline (TPHg) utilizing EPA Method 8015M, and benzene, toluene, ethylbenzene, xylenes (BTEX), and gasoline oxygenate methyl tertiary butyl ether(MTBE)by EPA Method 8021 B Groundwater well purge and sample logs are contained in Attachment 1