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1TIC ASS O C I ATE S I N C , groundwater contamination. Three of the soil borings were completed as groundwater monitoring wells and two of the soil borings were completed as vapor extraction wells. The soil boring, groundwater monitoring well, and vapor extraction well locations are shown on Figure 2 . Field activities and analytical results were detailed in Smith Technology' s Summary Report dated September 17, 1997. The report contained recommendations for the installation of additional soil borings and groundwater monitoring wells to fully delineate the vertical and horizontal soil and groundwater contamination. PHS/EHD agreed with these recommendations with minor modifications in correspondence dated November 13 , 1997. I-� Smith Technology, whose assets were purchased by ATC Associates Inc. on August 20, 1997, prepared a workplan for the additional soil and groundwater investigation and submitted the workplan and permits to PHS/EHD for review and approval on December 2, 1997. San Joaquin County Public Health Services Environmental Health Division (PHS/EHD) approved the ATC f workplan, with minor modifications, in correspondence dated March 9, 1998 . On March 24 and 25 , 1998, ATC personnel supervised the advancement of seven soil borings at u the site. Drilling was performed by V&W Drilling using hollow stern auger and direct push technology. In accordance with the approved workplan, four of the soil borings were completed as groundwater monitoring wells MW4, MW5 , MW6, and MW7. One soil boring was advanced to approximately 68 feet to determine the vertical extent of contamination and one soil boring was advanced at an angle under the on-site building. ATC conducted a well survey of any groundwater wells located within 2,000 feet of the site. The results of the site investigation and well survey were detailed in ATC' s Summary Report Subsurface Investigation, at 610 North Hunter Street, Stockton, California, dated August 14, 1998 . In March 1999, ATC personnel supervised the advancement of three soil borings at the site. - I Drilling was performed by V&W Drilling using hollow stem auger. One soil boring was advanced off site and two soil borings were advanced on site. Grab groundwater samples from two of the soil borings contained detectable concentrations of petroleum hydrocarbons. One on- site soil boring was advanced to approximately 65 feet bgs to define the vertical extent of j impacted soil. The results of the site investigation were detailed in ATC ' s Summary Report of Soil and Groundwater Investigation, at 610 North Hunter Street, Stockton, California, dated July ( � 165 1999 , In March 2000, ATC personnel performed a vapor extraction and air sparge pilot test at the site. The purpose of these tests was to evaluate vapor extraction and air sparging as viable remedial - options for impacted soil and groundwater at the site and to determine whether vapor extraction could sufficiently capture air sparge off-gas, to determine short-term volatile organic compound (VOC) flux rates, and to collect data to design an vapor extraction/air sparge system. The results - of the pilot test are detailed in ATC ' s Vapor Extraction and Air Spurge Pilot Test Results and Feasibility Study at the Farmer Property, 610 North Hunter Street, Stockton, California, dated November 2, 2000 . w:\wgrdpro\62596\reports\irp.doc 3