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&1EMORANDUM <br /> CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD - CENTRAL VALLEY REGION <br /> 3443 Routier Road, Suite A Phone: (916) 361-5600 <br /> Sacramento, CA 95827-3098 )� ATSS Phone: 8-495-5600 <br /> T0: Antonia K. J. Vo <br /> rster I� FROM: Camilla Williams <br /> Senior WRC Engineer Engineering Geologist <br /> DATE: 5 July 1991 SIGNATURE: �CdyrG�f�L"�L�CL!la�2� <br /> SUBJECT: REVIEW OF THE REMEDIAL INVESTIGATION/FEASIBILITY STUDY (RI/FS) REPORT, <br /> DEFENSE DISTRIBUTION REGION WEST (DDRW), TRACY SITE, SAN JOAQUIN COUNTY <br /> The P.I/FS Report for the DORW, Tracy Site (Tracy) was submitted on 4 March 1991 by the <br /> Corps of Engineers (COE) and prepared by Woodward-Clyde Associates (WWC) . The RI/FS <br /> Report was prepared and submitted prior to the signing of the Federal Facilities <br /> Agreement in June 1991 . In the June 1991 Project Manager's Meeting, Tracy indicated <br /> that it would like to use this Report as the RI/FS Report for an Operable Unit (OU) for <br /> the volatile organic constituents (VOCs) contaminated ground water in the northern part <br /> of the site. However, I have reviewed the RI/FS Report as a comprehensive Report so <br /> that Tracy may use the concerns and comments to prepare for the site-wide RI/FS Report. <br /> My major concerns are discussed below. <br /> REMEDIAL INVESTIGATION <br /> The RI at the Tracy site i s nearly complete with respect to the volatile organic <br /> constituent (VOC) ground water contamination in the northern portion of the site. The <br /> primary VOC contaminants are trichloroethylene (TCE) and tetrachloroethylene (PCE) . <br /> The maximum total VOC concentrations in ground water is less than 600 micrograms per <br /> liter (µg/1 ) , with the highest concentrations at LM-25. Tracy has made a significant <br /> effort in the investigation and cleanup of the site with respect to the nearly complete <br /> definition of the plume and an in-place IRM. Tracy has defined the lateral and <br /> vertical extent of ground water contamination, except at the leading edge of the plume. <br /> The RI Report recommends the installation of monitor wells to the northeast <br /> (downgradient) of LM-76 to complete the definition of the plume extent. I concur with <br /> this recommendation. Tracy has installed an Interim Remedial Measure (IRM) which was <br /> started in April 1991 . The IRM is regulated under Waste Discharge Requirements (WDRS) <br /> Order No. 90-275 adopted on 28 September 1990. The WDRs require quarterly ground water <br /> monitoring in the northern portion of the site. <br /> The only major deficiency of the ground water RI for the northern portion of the site, <br /> as well as for the entire site, is that a year of quarterly ground water level and <br /> quality data has not been collected and analyzed. Tracy belatedly begun a monitoring <br /> program, in May 1991, in response to the WDRs. At a minimum, four consecutive quarters <br /> of complete water quality data should have been collected for presentation in the RI <br /> Report. <br /> In the past, it appears that the focus of the remedial investigations have been only <br /> in the northern portion of the site for VOC contamination in ground water and the <br /> installation of the IRM were the priorities. However, now that these goals have been <br /> achieved, the focus of the overall site RI needs to shift to other areas. There <br /> appears to be three major areas that need to have additional work performed for the <br /> overall cleanup of the site. These areas are the implementation of a site-wide ground <br /> water monitoring program, soil and ground water investigations in the southern portion <br />