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S%ed.T` <br /> A A 4 <br /> < ,r, w <br /> q UNITED STATES ENVIRONMENTAL PROTECTION AGENCY <br /> ,,Z Molt6, REGION IX <br /> 75 Hawthorne Street <br /> San Francisco, Ca. 94105-3901 <br /> August 10, 1992 <br /> Marshall Cloud <br /> Superfund Project Manager <br /> famy M <br /> n <br /> Environmental Protection Office <br /> Bldg. 231, Tracy Location 6 <br /> Defense Distribution Region West AUG 17 1992 <br /> P.O. Box 960001 <br /> Stockton, CA 95296-0250 ENVIRONMENTAL HEALTH <br /> PERMIT/SERVICES <br /> RE: EPA Comments on the Draft FS for OU-1 <br /> Dear Marshall: <br /> Enclosed are EPA's comments on DDRW-Tracy's Operable Unit <br /> No. 1 (OU-1) Draft Feasibility Study (FS) , received in our <br /> offices on June 10, 1992 . Per the terms of the Federal Facility <br /> Agreement (FFA) , EPA is providing comments within 60 days of <br /> receipt. <br /> DDRW-Tracy has raised questions regarding the <br /> representativeness of the total metals ground water data which <br /> indicate elevated levels of metals on-site. DDRW-Tracy prefers <br /> to redefine the scope of this OU to delete metals from <br /> consideration until the development of the Comprehensive RI/FS <br /> (scheduled for December 6, 1993) . Consequently, the draft FS for <br /> OU-1 does not present a plan of remedial action for metals. <br /> Although partly explained in the text of the current draft FS, <br /> the change in definition for OU-1, the rationale for the change, <br /> and the commitment to address the question of metals <br /> contamination in a subsequent part of the RI/FS, needs to be more <br /> strongly emphasized and explained in the Executive Summary, the <br /> Introducti6n, and the sections addressing Nature and Extent of <br /> Contamination and the Risk Assessment. <br /> As currently written, the FS further narrows the scope of <br /> OU-1 by deselecting organic chemicals of concern identified in <br /> the RI. This approach introduces further discrepancies between <br /> the FS and the RI and is not advisable. Instead EPA DDRW-Tracy <br /> should retain the organic chemicals of concern and explain how <br /> the remedies evaluated for TCE and PCE will address these <br /> contaminants. This approach has been used successfully in other <br /> Feasibility Studies. <br /> As stated in our comments, the first three alternatives <br /> presented in Sections 3 (and those carried into Section 4) do not <br /> 1 <br /> Printed on Recycled Payer <br />