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110 Sonora, Stockton, chronology <br /> Page 4 <br /> ywas confirmed:.in three (2N, 2S and 6N) of 16 samples collected <br /> beneath the piping at 4 feet and one sample collected at 11 feet <br /> where the BUST was formerly located. <br /> 718 & 15102 Geoprobe borings; P1 — P5, were advanced in the areas where soil <br /> contamination was found during the April 2002. piping removal. <br /> 07/24/02 Date of EHD letter-requesting a work plan for adding ozone <br /> injection to.the existing remediation:.system as. proposed by the <br /> consultant during. a July 11,:2000,. meeting. <br /> 08/12/02 Date of Preliminary Site Assessment on geoprobe investigation in <br /> July. 2002. The grab water samples were,all non detect. Soil <br /> contamination was found to a depth of 20 feet in area of piping <br /> samples 2N and 2S, all other soil samples were non detect. The <br /> report recommends excavation.and disposal of the contaminated <br /> soil. <br /> 09/11/02 Excavation of about 275 yards of contaminated soil from the piping <br /> sample. 2N and 2S.area occurred this date. <br /> 1 <br /> j 11/20/02 Date of Interim Soil Remediation Report on the excavation, <br /> disposal and soil sampling of the piping sample 2N and 2S area in <br /> September 2002. The report recommends no further investigation <br /> of this area.. <br /> a 03/03/03 Installation of MW6 (screened 60 — 65.feet), in the area where Tank <br /> 1 was located,"occurred this date. <br /> 0512003 The operation of the'soil vapor extraction system was terminated <br /> :because vapor samples were non detect. <br /> 06/13/03 Date of Quarterly Monitoring report that includes information on <br /> installation of MW6. No soil samples were analyzed. <br /> 07/01/03 An ozone sparging system was installed utilizing_ the existing IAS <br /> + wells. <br /> I 01/25/05 Date of EHD letter:requiring installation of an ozone well near <br /> VW2d designe`a by the manufacturer of a micro sparging system. <br /> I <br /> 1 <br />