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MEMORANDUM CALIFORNIA REGIONAL ATER QUALITY CONTROL BOARD CENTRAL VALLEY REGION 3443 Routier Road, Suite A Phone: (916) 255-3000 Sacramento, CA 95827-3098 CALNET: 8-494-3000 TO: Antonia K. J. Vorster P FROM: Camilla Williams Senior WRC Engineer f,, —Associate Engineering Geologist James D. Taylor Associate Engineering Geologist DATE: 4 June 1993 SIGNATURE: SUBJECT: DRAFT RECORD OF DECISION (ROD), OPERABLE UNIT NO. 1, DEFENSE DISTRIBUTION REGION WEST (DDRW), TRACY, SAN JOAQUIN COUNTY I have reviewed the Draft ROD for Operable Unit No. 1 (OU-1) for the DDRW, Tracy site submitted on 6 April 1993. The Draft ROD was prepared by Woodward Clyde for the Corps of Engineers (CoE) . Overall , the Draft ROD is well organized and well written. Our primary concern with the Draft ROD is that it does not clearly state that DDRW, Tracy will discharge its treated groundwater according to waste discharge requirements (WDRs) issued by the Board for OU-1 . We plan to issue WDRs prior to implementation of the remedial action. The effluent limits to be established in the WDRS are presented below. The effluent performance standards in the ROD must be consistent with the effluent limits established in the WDRs. The Draft ROD appears to address, in part, our outstanding concerns with the Feasibility Study (FS) Report. Specifically, our concerns regarding the extraction and disposal systems have been partially addressed, but will require additional revisions prior to our approval . Our other concerns regarding the ground water monitoring program frequencies, Applicable or Relevant and Appropriate Requirements (ARARs) and other minor comments are discussed in more detail below. MAJOR COMMENTS 1 . Waste Discharge Requirements (WDRs). The Draft ROD does not accurately reflect the status of existing or pending discharges regulated under the Board's WDRs. Currently, DDRW, Tracy has two WDRs: 1) No. 89-209 which regulates discharges from the on-site waste water treatment plant to the evaporation/percolation (EP) ponds and discharges to the storm water pond; and 2) No. 90-275 which regulates discharges from the Interim Remedial Measure (IRM) to the reinjection wells and to the storm water pond from May to October. By letter dated 29 March 1993, we authorized the temporary discharge of the treated ground water to the EP ponds and early discharges to the storm water pond in 1993 so that the IRM could continue to operate while the reinjection wells were rehabilitated. DDRW, Tracy has applied for a permit for discharge of the OU-1 treated ground water. On 15 May 1993, DDRW, Tracy submitted a Report of Waste Discharge (RWD) for OU-1 . We will modify the existing WDRs for the IRM to include increased flows and disposal of the treated ground water to surface impoundments (ponds) as well as reinjection. In Section 10.4.7, the Draft ROD should clearly state