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Ja�{ED Si,,l0 UNITED STATES ENVIRONMENTAL PROTECTION AGENCY APR 0 2 2003 <br /> i � s 75 Hawtho�ne Street ,,,j ,IjvirbgT HEALTH <br /> �v4< San Francisco CA 94105-3901 FLr-iUff/SERVICES <br /> PP <br /> March 19, 2003 <br /> Mr. Marshall Cloud <br /> Defense Distribution Depot San Joaquin California,Tracy Site <br /> DDJC-FA, Attn: Environmental Management <br /> P.O. Box 960001 <br /> Stockton, CA 95296 <br /> RE: Response to Comments,Draft Project Closeout Plan (Remedial Action Report) <br /> Northern Depot Area (DSERTS 67) Cover Installation Defense Distribution Depot <br /> San Joaquin (DDJC) Tracy Site, Tracy, California <br /> EPA Review Comments,Draft Final Project Closeout Plan (Remedial Action <br /> Report) Northern Depot Area (DSERTS 67) Cover Installation Defense Distribution <br /> Depot San Joaquin (DDJC) Tracy Site,Tracy, California,January 2003 <br /> Dear Marshall, <br /> Please find EPA's review of the above referenced documents in two attachments to this <br /> letter. <br /> The main body of text of the Draft Final RAR was substantially revised to follow the <br /> current EPA guidance for a RAR, however, a Cost and Performance Summary was not provided <br /> as an appendix. The Executive Summary recommends "no further remedial action," which is not <br /> consistent with EPA Guidance for Records of Decision (RODS) and post-ROD documents. We <br /> included comments requesting the next version of this RAR to follow these aspects of the EPA <br /> Guidance. <br /> A Design Data Collection Effort (DDCE) was conducted in 1999 to fill design data gaps <br /> and assess the nature and extent of contamination at DSERTS 67. The data obtained through the <br /> DDCE were reportedly used to support the Explanation of Significant Differences (ESD), which <br /> changed the ROD-selected asphalt cover to an aggregate base (AB) cover augmented by <br /> institutional controls. Also, the results of the DDCE were reportedly used to justify the reduction <br /> of the size of the cover from the ROD-estimated 138,000 square feet to approximately 63,500 <br /> square feet, which cut the cover size by 54 percent and appeared to leave contamination in place <br /> in the northwest portion of the site. This change in size should be supported through the ESD or <br /> ROD Amendment process. Comments are included to address the DDCE, the application of its <br />