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0 <br />SPATE OF CALIFORNIA — ENVIRONMENTAL PROON AGENCY PETE WILSON, Govenai <br />CALIFORNIA REGIONAL WATER QUALITY Y -F +( RD-- <br />CENTRAL VALLEY REGION i11 <br />3443 ROUTIER ROAD, SUITE A <br />SACRAMENTO, CA 95827-3098 , <br />PHONE: (916) 255-30001® <br />FAX: (916) 255-3015 PH 47 <br />3 March 1995 <br />Mr. Paul Verma <br />City of Tracy <br />520 Tracy Boulevard <br />Tracy, CA 95376 <br />We have reviewed the report of soil sampling and analyses from the City's land treatment facility, <br />submitted on your behalf on 21 December 1994 by Wright Environmental Services. <br />Accompanying that report was an updated version of the proposed sampling workplan, earlier <br />versions of which we had already reviewed, and a statement of Wright Environmental Services' <br />protocols for field sampling and well installation. <br />Our review of these documents found some discrepancies between the sampling methods and <br />analytical procedures that we agreed upon and those that apparently were actually used. We also <br />found that documentation of the field and laboratory procedures was inadequate and unclear. <br />These and other problems are summarized in the attached memo. <br />Review of the analytical results shows that the soils still contain detectable levels of diesel, other <br />hydrocarbons, and gasoline components (BTEX). The analyses do not appear to have been done <br />according to the specifications of the Tri -Regional Board Staff Recommendations for Preliminary <br />Investigation and Evaluation of Underground a Sites (1990) , as we required. For example, <br />although the submitted lab reports do not clearly specify the quantitation limit used in the USEPA <br />Method 8020 analysis for BTEX, they state the results as "< 0.04 ppm" (for BTE) and for <br />xylenes, as "<0.08 ppm". This suggests that 0.04 ppm and 0.08 ppm, rather than the 0.005 ppm <br />our staff recommends for soils, were the quantitation limit used. In addition, the WDRs specify <br />the use of grab samples, not composited samples, for BTEX detection. Therefore, it is not <br />appropriate to average the sample results, even if the individual samples were taken as grabs. <br />Based on our review, we find that these soils are inappropriate for unrestricted reuse. However, <br />as part of the effort to close your land treatment facility, we will approve reuse of the soils in <br />projects, such as the construction projects proposed in the subject report, that involve <br />encapsulation of the soils between a covering layer of asphalt or other low -permeability surface and <br />an underlying, low -permeability compacted layer. Use in areas of shallow groundwater (5 feet <br />below the fill, whether seasonal or year-round) or in areas of high -permeability undersoils (sands, <br />silts) without a compacted underlayer is unacceptable. Further, the soils containing hydrocarbons <br />