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STATE OF CALIFORNIA•Environmental Protecti0noency • PETE WILSON,Governor CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD CENTRAL VALLEY REGION 3443 Routier Road,Suite A -- Sacramento,CA 95827-3098 PHONE:(916)2553000 FAX:(916)2553015 19 December 1996 Mr. Jim Pinasco Department of Toxic Substances Control 10151 Croydon Way, Suite 3 Sacramento, Ca 95827-2106 OPERABLE UNIT 2 PRE-DESIGN TECHNICAL SUMMARY, DDRW-SHARPE, SAN JOAQUIN COUNTY We have reviewed the Operable Unit Pre-Design Technical Summary, dated October 1996, for the DDRW-Sharpe facility. The purpose of this report was to present the results of additional field work conducted to verify how these results correlated with previous findings, and develop remedial designs as required by the Final Basewide Record of Decision for Operable Unit 2 (OU2 ROD) at the DDRW- Sharpe site. The field work consisted of soil vapor surveys and soil sampling for metals contamination. We commend Sharpe and its consultants on a good effort to collect useful data in the field. We have four general concerns with the Pre-Design Technical Summary. The first concerns is we believe that the OU2 ROD requires that the soil gas data collected as part of this report are to be evaluated to determine the potential impacts to water quality, not the technical and economic analysis for volatile organic contaminant(VOC) cleanup as presented. Secondly, the Pre-Design Technical Summary, which has been considered a secondary document, does not appear to be the appropriate document for closing sites with no further action when the ROD requires cleanup actions at these sites. It therefore is necessary to document all areas proposed for no further action in a primary document. We are also concerned that historic locations of high VOC soil gas data do not correlate well with the sample locations performed in the field work and finally, the recommendation for addressing metals in the South Balloon area. These concerns are expanded in the following sections. General Comments 1. Soil gas surveys were conducted in sixteen areas identified as potential sources of VOC contamination degrading groundwater underlying the Sharpe facility. Based on the OU2 ROD, seven sites out of the sixteen were identified in the ROD as source areas for groundwater contamination based on 1987 data. The ROD requires ISV for these sites. These seven sites were to be further characterized in order to design an in-situ volatilization system. Five of these sites will proceed to ISV remediation. Two of these sites have been proposed for no further action based on the Pre-Design data. We question the validity of the field sampling in these two areas as further described in comment# 3 of this letter.