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JURE">F UNITED STATES ENVIRONMENTAL PROTECTION AGENCY <br /> _ Region 9 <br /> 75 Hawthorne Street <br /> San Francisco CA 94105-3901 <br /> January 25, 1999 <br /> Marshall Cloud <br /> Environmental Protection Office <br /> DD-Tracy <br /> P.O. Box 960001 <br /> Stockton, CA 95296-0250 <br /> RE: DD-Tracy Addendum to Future Development Report, DDJC Tracy Site, Draft, <br /> December 1998 <br /> Preliminary Institutional Control Slip Pages to Draft Final DDJC-Tracy <br /> Remedial Design Work Plan, 18 December 1998 <br /> Dear Marshall, <br /> Thank you for the above referenced material. EPA's comments are as <br /> follows. <br /> 1. Depot Wide Surface and Near Surface Soils, Northern Depot Area site <br /> Per the Final Site-Wide Comprehensive ROD, sites which have <br /> Institutional Controls (ICs) as the remedy, or part of the remedy, are: <br /> SWMU 7, SWMU 33, and Building 30 Drum Storage Area. Both the Addendum to <br /> Future Development Report, and the slip pages to the Remedial Design Work <br /> Plan understandably address ICs for these three sites. However, another <br /> site which is not addressed by these documents is the Depot Wide Surface and <br /> Near Surface Soils, Northern Depot Area site. Although not explicitly <br /> identified as an IC site in the ROD, this site relies upon a new asphalt <br /> cover to protect human exposure from underlying contaminants. As indicated <br /> in Section 9.7. 9.4 of the ROD, "this asphalt cover will be maintained for as <br /> long as soil concentrations exceed the establish cleanup standards." Thus <br /> this site is fundamentally the same as SWMU 7, SWMU 33, and the Building 30 <br /> Drum Storage Area, in that the overlying facilities or cover must stay in <br /> place in order for the remedy to stay effective. <br /> Just as Ica are the mechanism to ensure that the cover stays <br /> in place at SWMU 7, SWMU 33, and the Building 30 Drum Storage Area, so <br /> should ICs be the mechanism to ensure the integrity of the new asphalt cap <br /> at the Northern Depot Area site. The Five-Year Review process would not be <br /> expected to adequately serve this purpose because: 1) the integrity of the <br /> asphalt cap could become compromised any time between Five Year Review <br /> periods, and 2) the asphalt cap may need to remain in place for many <br /> decades, which may extend beyond the time frame of the Five Year Review <br /> CERCLA authority. Thus, please revise the Future Development Report, and <br /> the slip pages to the Remedial Design Work Plan, to include ICs for the <br />