SITE INFORMATION AND CORRESPONDENCE_1992

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MEMORANDUM • CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD - CENTRAL VALLEY REGION 3443 Routier Road, Suite A Phone: (916) 361-5600 Sacramento, CA 95827-3098 ATSS Phone: 8495-5600 TO: Antonia K. J. Vorster �V'I , FROM: Camilla Williams Senior WRC Engineer Engineering Geologist DATE: 17 April 1992 SIGNATURE: SUBJECT: DRAFT SOILS FEASIBILITY STUDY (FS) REPORT, DEFENSE DISTRIBUTION REGION WEST (DDRW), SHARPE, SAN JOAQUIN COUNTY I have reviewed the Draft Soils Feasibility Study Report submitted on 18 February 1992. The Draft FS Report was prepared by Environmental Science and Engineering (ESE) for the U. S. Army Toxic and Hazardous Materials Agency (USATHAMA) . The Draft Soils FS Report was accompanied by three supporting documents: Problem Assessment Report (PAR) for Underground Storage Tanks (USTs) , Vapor Extraction Pilot Study Report and Soils Risk Assessment Report. The first two supporting documents were reviewed by other staff in our office and their reviews are attached as separate memorandums. We defer the review of the Soils Risk Assessment Report to the Department of Toxic Substances Control (DTSC) . In general , the soils investigation of WMUs and USTs at DDRW, Sharpe is inadequate. The existing data are inadequate because they do not indicate whether ground water quality will be protected nor is the data base adequate to develop remedial actions. In addition, new sources of soil and ground water contamination have been identified which will require additional investigation to define the extent of contamination. Unless additional data are developed for the WMUs and USTs, the potential remedial alternatives for soil cleanup cannot be considered. The ground water investigation has focused primarily on contamination by solvents and the pending site-wide, comprehensive ground water Record of Decision (ROD) and remedial action are intended only to address ground water contamination by volatile organic constituents (VOCs) . Information submitted in the Draft Soils FS Report shows that ground water has been contaminated with semi-VOCs, polychlorinated biphenyls (PCBs) , heavy metals and other potential contaminants, not yet identified due to the inadequate investigation of waste management units (WMUs) and USTs. The upcoming ROD cannot be considered comprehensive because it will not address all ground water contamination at DDRW, Sharpe. Unless the pending ground water ROD is limited to cleanup of the VOC (solvent) ground water contamination, it will not be acceptable. Investigation and cleanup of ground water contaminated with constituents other than solvents will have to be done in a separate effort and ROD. I have several major concerns with the Draft Soils FS Report which are summarized below. Specific comments on this Report are summarized after the discussion on the major inadequacies of this Report. MAJOR CONCERNS 1. The level of remedial investigation at WMUs and USTs is inadequate on which to base a FS of remedial alternatives and is inconsistent between the two Defense Logistics Agency (DLA) sites (DDRW, Sharpe and DDRW, Tracy) . Many potential ground water impacts by contaminants other than solvents at DDRW, Sharpe have either not been investigated or the existing investigation is inadequate. The