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e <br /> UNITED STATES ENVIRONMENTAL PROTECTION AGENCY <br /> REGION IX <br /> 75 Hawthorne Street <br /> San Francisco,CA 94105 <br /> May 4, 2004 <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: Review of the Response to Comments on the Draft Explanation of Significant <br /> Differences (ESD) to the Site-Wide Comprehensive Record of Decision and <br /> Review of the Draft Final ESD, Defense Distribution Depot San Joaquin <br /> (DDJC) Tracy Site, Tracy, California, April 2004 <br /> Dear Mr. Cloud: <br /> The U.S. Environmental Protection Agency (EPA) Region 9 has received the Response to <br /> Comments (RTC) on the Draft Explanation of Significant Differences (ESD) to the Site-Wide <br /> Comprehensive Record of Decision (ROD), and the Draft Final ESD, Defense Distribution <br /> Depot San Joaquin (DDJC) Tracy Site,Tracy, California, dated April 1, 2004. We have <br /> reviewed the aforementioned documents and our comments are enclosed. <br /> It appears that the most recent version of RTC was not included in the Draft Final ESD. A <br /> replacement RTC was issued April 23, 2004, but there was no written response to EPA's <br /> comments submitted on March 3, 2004. Based on the review of the most recent RTCs and a <br /> review of the Draft Final ESD, several issues regarding the ESD remain. <br /> We recommend a thorough revision of Section 4.0, SWMU 8. There appear to be two <br /> cleanup standards proposed for DDT and the supporting decision logic used to justify protection <br /> of human health and groundwater with contamination left in place is confusing and difficult to <br /> follow. We have included comments suggesting where revisions should occur. <br /> In addition, we do not agree that the question of backfilling the excavation is addressed, as <br /> stated in the response to Specific comment 2 on the Draft ESD (comments dated February 5, <br /> 2004). Although the detailed discussion should be provided in the Remedial Action Report for <br /> SWMU 8 as mentioned in our March 3, 2004 review comments, both Section 4.2.1.5. and Table <br /> 4-3 of the ESD should be revised to summarize the justification for the determination not to <br /> excavate further. We have included comments suggesting the changes. <br />