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0 <br /> Re-Manufacturing, Ltd. -4- 26 June 1991 <br /> Closure Plan <br /> maximum density obtainable at optimum moisture content. The plan did not include <br /> a discussion of the engineering properties of the embankment material or <br /> supplemental make-up soils and did not demonstrate that either material was <br /> appropriate as foundation material . What is the source of the clean make-up soils <br /> and is it appropriate material? What tests will be run to assure the foundation <br /> layer is compacted to the maximum density obtainable, is at the optimum moisture <br /> content, and will have sufficient strength to support the engineered final cap? <br /> 4. Section 2581 (a) (2) requires at least one foot of soil containing no waste or <br /> leachate, placed on top of the foundation layer and compacted to attain a <br /> permeability of either I x 10-6 cm/sec or less. The closure plan proposes to meet <br /> these criteria. However, the permeability criteria stated applies to a class II <br /> or class III cap. The discharger proposes to leave soils containing hazardous <br /> levels of soluble lead in place. The permeability of a class I cap should be <br /> 1 x 10' cm/sec or less or an engineering alternative allowing for equivalent <br /> protection shall be proposed. The Closure Plan does say that permeability <br /> determinations for the cover materials will be as specified in Section 2541 of <br /> Chapter 15 and will be appended to the closure and maintenance report. When will <br /> the closure plan amendment be submitted? A Construction Quality Assurance plan <br /> should be submitted, which includes a description of specific tests to verify that <br /> permeability requirements will be met. <br /> 5. Figures 13 and 14 show pre- and post-excavation elevations, according to page 7 <br /> of the closure plan. Cross-sections showing the limits of the excavation and <br /> profiles showing the construction of the cap, foundation layer, placement of the <br /> drainage net, soil protective layer, etc. should also be submitted. The closure <br /> plan does not present a clear picture of how the closure cap will be constructed. <br /> 6. Figure 15 shows post-closure final grade contours. The grade exceeds ten percent <br /> slope. Section 2581(b) (2) requires erosion control for areas with slopes greater <br /> than 10 percent, surface drainage courses, and areas subject to erosion. How does <br /> the drainage over the final cap tie into the rest of the sites drainage, the storm <br /> drain, and the slough? Will the final cap be in contact with the high water mark <br /> in the slough (the 100-year storm event level )? <br /> 7. According to Section 2580(a) of Chapter 15, the post-closure maintenance period <br /> shall extend as long as the wastes pose a threat to water quality. The plan <br /> proposed post-closure maintenance for one year. Why? <br /> 8. As stated in #4 above, a Construction Quality Assurance (CQA) plan should also be <br /> submitted. The CQA plan describes the construction quality assurance procedures <br /> for the final cover. This plan shall include a description of quality control <br /> tests that will be conducted to confirm the required material properties, confirm <br /> that field permeability requirements are met, etc. , in order to assure that the <br /> construction criteria in the closure plan will be met. It should verify that <br /> proper construction techniques and procedures will be used and that the design <br /> specifications will be met. The CQA should also specify testing frequency. A <br /> construction report (as built) must be submitted at the completion of the project. <br />