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1 Gtologtca1 7'ech=1= Page 2 Dual Phase Extraction Pilot Test Report Project No 723 2 November 12, 2004 ' Prior to the early 1970's Crandle operated a John Deere facility on this property In the early 1970's Quimby purchased the property from Crandle and operated J M Equipment which is an equipment sales and service business In 1991 the property was transferred from Quimby to Geo Corp Apparently the tanks were installed during the time Quimby operated a John Deer facility and J M Equipment continued to operate them until they were removed in the ' early 1980s In April, 1999, responsibility for the adjacent independent trucking facility monitoring wells ' MW-1, MW-2, MW-3, MW-8 and MW-9 we"e transferred to J M Equipment Geological Technics Inc (GTI) also completed site investigation work which included the installation of three additional monitoring wells, two hand borings to 15 feet below grade surface (bgs), ' three soil bonngs advanced to 30 feet bgs, and one deep boring to 70 feet bgs The three new wells, MW-4 through MW-6, and five existing wells have been monitored quarterly since ' January 2000 In an effort to define the lateral extent of petroleum hydrocarbons, three soil borings, MW-7, MW-10 and SB-6 were advanced in May 2001 The borings were located approximately 200 feet southwest, 150 feet northwest and 100 feet west of, respectively, the ' former UST location (see Figure 2) To define the vertical extent of petroleum hydrocarbons, one soil boring, MW-109 was also advanced to 80 feet bgs in the location of the former UST Borings MW-7, MW-10 and MW-109 were converted into monitoring wells The data indicates that a significant gasoline plume is present in groundwater at the site GTI submitted our September 20, 2002 "In-Situ Remediation" Feasibility Study to the San ' Joaquin County Public Health Department/Environmental Health Division (SJC PHS/EHD) for approval GTI proposed the preparation of a work plan for a small scale in-situ oxidation pilot test The pilot test would include injecting hydrogen peroxide (H2O2) and ozone into the subsurface utilizing two to three small diameter injection wells located within five to ten feet of an existing monitoring well The H2O2 and ozone would combine to form the hydroxyl radical, which would then break down the BETX and TPH in the groundwater and ' capillary zone at the site On September 30, 2002, SJC PHS/EHD staff called GTI regarding the feasibility study plan ' They requested that we provide case history data to show that in-situ injection of hydrogen peroxide has worked on other similar sites Our January 15, 2003 "Addendum — In-Situ Remediation Feasibility Study" included the requested information and the SJC PHS/EHD ' approved the study in their March 20, 2003 letter correspondence They also directed that a detailed work plan for the feasibility pilot test be submitted for approval GTI submitted our ' June 10, 2003 "Pilot Test for In Situ Remediation" work plan to meet the SJC PHS/EHD requirements SJC PHS/EHD approved the work plan in their September 10, 2003 correspondence ' The following sections detail the installation of three monitoring wells at the site and the subsequent use of the wells to monitor the in situ chemical oxidation (ISCO) pilot test