COMPLIANCE INFO_FILE 2 - Laserfiche WebLink

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IN,11-. Ohland 2 11) December 100-1 constructed on the site after earlier operations had ceased, the analytical results from the: subliner soils may reflect pre-existing site conditions. However, the rather high levels of TDS rind chlorides in ground water from boring SLB-1, a subliner sample, suggests that leakage from the impoundments occurred. It is therefore impossible to conclude from available data whether the impoundments leaked or not. 2. USE OF BERM SOILS AND/OR OTHEIZ ON-SITE SOILS TO BACKFILL OR COVER THE IMPOUNDMENTS: Although the sample results show that the subliner and berm soils are "cleaner" than the highest- concentration spots on the site, they also show that the impoundment area contains higher concentrations than the "cleanest" areas on the site. As noted, we believe that the analytical results indicate contamination from site activities (which may or may not include impoundment leakage). Based on this, we prefer that you not use any berm soils in backfilling the impoundments unless You can show that the soils contain lower concentrations than any of the subliner samples, and that the berm "hot spots" are excluded. Berm soils that are not used in backfilling should be stockpiled on the site, under protective cover, and remediated with the remainder of the site's solid wastes. Your closure request states that you plan to cover the impoundment area with "natural cover' obtained from the site. Given the permeability of the soils and the presence of contamination, this proposal is unacceptable for a final cover, regardless of whether you are trying to achieve a "clean" closure under the requirements of Section 2582.b.1, Calfornia Code of Regulations, Title 23, Division 3. Chapter 15 (Chapter 15), or a landfill closure under the requirements of Section 2581. Chapter 15. For clean closure, any material added to the impoundment area must be clean, that is, concentrations of TDS, chlorides, or other salts must be equal to or lower than the least- contaminated spots on the site. 3.REMOVAL OF CONTAMINATION "HOT SPOTS" FOUND UNDER THE IMPOUNDMENTS: We consider hot spots found within the impoundments subliner as evidence of contamination, even if the analyses indicate lower concentrations than the "Threshold Limit Value" referenced in your closure request. (See discussion under-Item 4 below). The hot spots should be removed to a depth such that re-analysis shows salt levels equal to or l?ss than the least-contaminated spots on the site. This should be done before the impoundments are backfilled. The removed soils may be stored under protective cover with the berm soils that are not used in backfill, in an already-contaminated area of the site. This conclusion is based on our determination that the method used by your consultants to determine background concentrations of constituents of concern in the site soils is inappropriate and not protective of water quality.