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Page 2 <br /> Chronology <br /> 24500 MacArthur Drive, Tracy <br /> 7/13-28/98 Excavation of 1522 cubic yards of contaminated soil. Soil to be <br /> aerated on site. Excavation filled with clean material. Pot holes dug <br /> to define the lateral & vertical extent of contamination because all <br /> contaminated soil could not be removed. <br /> 09/2/98 AGS "Report For Remedial Soil Excavation and On Site Aeration <br /> documents work performed in July 1998. <br /> 09/17/98 AGS supervised installation of MW1A near the former tank location, <br /> to replace MW1 'destroyed prior to excavating. <br /> 10/28/98 AGS report on-Soil Aeration. Analytical data indicated soil can be <br /> left spread on the site. <br /> 11/20/98 EHD letter approving soil be left where it had been placed on site. <br /> 09/07/99 AGS "Case Closure Request Report" showing contaminant levels <br /> reduced. <br /> 11/18/99 AGS addendum to closure request containing well survey, revised <br /> site map, and tables of soil analytical data. <br /> 12/23/99 EHD requested concurrence from Central Valley Regional Water <br /> Quality Control Board (CVRWQCB) on "no further action required" <br /> for this site. . <br /> 02/07/00 CVRWQCB letter not concurring with no further action request. <br /> Requires that it be demonstrated that the oldest production well <br /> (South Well) is not a conduit for contamination to reach the lower <br /> aquifer. <br /> 03/18/04 New production well installed upgradient of contamination. Well is <br /> 500 foot deep and has4a 200 foot annular cement grout seal. <br /> 03/24/04 Monitoring wells sampled. <br /> 05/27/04 Old production well (South well) destroyed by explosion and filling <br /> with cement grout. <br /> 06/16/04 Date of"Monitoring Report Ground Water Sampling March 24, <br /> 2004 and Case Closure Request" documenting work performed at <br /> site since November 1999. <br />