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r. A• s <br /> p� UNITED STATES ENVIRONMENTAL PROTECTION A 'ER�`�%;•;',c:�`�,t�Qp�, t{ra(TN <br /> �Ac r-,0 REGION IX <br /> 75 Hawthorne Street P44 38 <br /> San Francisco, Ca. 94105-3901 <br /> June 7, 1993 <br /> Marshall Cloud <br /> Env. Protection Office <br /> DDRW-Tracy <br /> P.O. Box 960001 <br /> Stockton, CA 95296-0250 <br /> RE: Draft ROD for OU #I for DDRW-Tracy <br /> Dear Marshall, <br /> EPA has completed our review of the Draft Record of Decision (ROD) for Operable <br /> Unit No. 1 (OU #1) for DDRW-Tracy, a document received in our offices on April 6, 1993. <br /> Pursuant to the terms of the Federal Facility Agreement (FFA), EPA is providing comments <br /> (attached) within 60 days of receipt of this document. <br /> The objectives of this ROD are, in part, to provide a complete and clear record of <br /> the decision-making process which selects the remedy for OU #1. EPA's major concerns <br /> with the draft ROD are that, as currently written, the ROD: <br /> 1. presents an incomplete record of the decisions which have resulted in the setting of <br /> aquifer cleanup levels for three of the 17 possible chemicals of concern (CoCs) listed <br /> in the FS. <br /> 2. uses inconsistent definitions for OU 01. <br /> 3. uses indeterminate text regarding the selection of disposal mechanisms for treated <br /> groundwater. <br /> 4. does not determine the applicability of a number of potential ARARs. <br /> EPA is also concerned that statements in this document minimize the significance of <br /> metals and dieldrins that have been detected in groundwater monitoring rounds. <br /> Carcinogenic risks posed by concentrations of dieldrin and arsenic in areas where detected <br /> 1 EPA regards several of the solid waste management units (SWMUs) as likely to <br /> contributors of metals and pesticide contamination at DDRW-Tracy. The industrial waste <br /> ponds (IWPs, SWMU No. 3) and the industrial waste pipeline (IWPL, SWMU No. 33) with <br /> associated sumps are known to contain, or at least to have contained, some concentration of <br /> all heavy metals and pesticides (AEPCO, Inc. 1991). Monitoring wells LM3, LM15, LM49, <br /> LM101, LM103, and LMI04 are all immediately downgradient from either the IWPs or the <br /> IWPL or both. Additionally, significant concentrations associated with human health risk <br /> for arsenic (filtered and unfiltered samples) and for dieldrin have been detected since 1985 <br /> in each of these monitoring wells. <br /> 1 <br /> Printed on Recycled Paper <br />