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State of California Department of Health Services r To Jeanine Jones, P.E. Date September 23, 1986 Senior Waste Mana ement. Engineer Subject: Lika Field Avenue Report, dated August 5, 1986 R Marge ouch From Waste Management Engineer After reviewing the "Preliminary Investigation for Surface and Subsurface Contamination of Soils and Groundwater Final Report" , the following are my comments, questions and suggestions for proceeding on this project. The Total Threshold Concentration Limit (TTLC) is used to determine if a waste is hazardous; it should not be considered a goal or cleanup level. The statement which starts at the bottom of page 6-i is not correct. If the soil has a concentration of toxic contaminants which exceed the TTLC, the soil is considered hazardous in situ, not just at the time of excavation and 'disposal. The analytical results for hexavalent chromium are inadequate. Regarding item 1 on page 6-5, the 0. 10 mg/l limit of detection for hexavalent chromium (CrVI) in water is too high. The Primary Drinking Water Drinking Water Standard is only 0. 05 mg/l. I can find no record of standard method 312 (page 5-1) for hexavalent chromium analysisi What document describes this method? The letter from California Analytical Laboratories, dated June 3, 1986 (Appendix C) , states there was high interference for CrVI determination, which raised the detection limit. A laboratory report or quality control summary submitted to Woodward-Clyde should be included in this section of the report to explain any problems encountered while doing the analyses. All wells should be resampled and analyzed for CrVI according to EPA Test Methods for Evaluating Solid Waste, SW-846 2nd Edition, before abandonment of the wells can be considered. 'The recommendations proposed for excavation of a maximum of two feet of soil along the west side of the building appears adequate, except in areas B-4 and LSB-7. The copper in the soil samples in these two locations becomes more concentrated with depth. Soil excavation and removal in these two areas should go deeper than the proposed two feet. After the soil is removed, confirmation sampling must be done to show the effectiveness of the excavation. The confirmation samples should be taken, as closely as possible, in the same areas as the original sampling .effort.