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Mr. Greg Basso -3- January 25, 1988 <br /> 8. The Closure Plan does not outline a procedure to establish <br /> a correlation between the desired permeability and the <br /> density at which that permeability is achieved. DHS <br /> recommends using field permeability testing in conjunction <br /> with the laboratory tests described in the Closure <br /> Plan. This would involve using a sealed double wall <br /> infiltrometer on a test pad to find in-situ permeability. <br /> Nuclear gage testing should also be conducted on the test <br /> pad along with shelby tube samples tested by flexible wall <br /> permeability tests. The combination of the lab tests and <br /> the infiltrometer test, in correlation with the nuclear gage <br /> tests, would be considered adequate to insure a minimum <br /> permeability of 1 x 10-6 cm/s in field conditions for the <br /> clay liner. <br /> - 40 CFR 265. 115 <br /> - 22 CCR 67288 (g) <br /> 9. The Closure Plan does not describe the methods to be used to. <br /> remove vegetation, organic topsoil, and debris from the <br /> cover materials. DHS requires a detailed description of <br /> how all vegetation, topsoil, debris, rocks, and clods will <br /> be removed from all cap materials and written standards that <br /> the soil must meet before placement to insure permeability. <br /> In addition, DHS requires a quality assurance/quality <br /> control (QA/QC) plan to insure that the cover will meet <br /> minimum approved standards. <br /> - 40 CFR 265.310 <br /> - 22 CCR 67409 (a) <br /> 10. A water drainage/filter layer, which lies between the <br /> vegetative layer- and the clay liner, is required unless <br /> technical documentation can demonstrate that this <br /> requirement is unnecessary for this facility and cap design. <br /> 22 CCR 67288 (f) (9-10) <br /> 11. The QA/QC plan for construction of the cover is not <br /> provided in detail. The QA/QC plan should include the <br /> duties and responsibilities of the QA/QC person. In <br /> addition, it should include contingencies for lifts that <br /> fail compaction or lab tests and the decision process for <br /> each contingency. The QA/QC work should be conducted by an <br /> engineer or geologist employed by a firm that is independent <br /> of the firm that is doing the actual construction. <br /> - 40 CFR 265. 115 <br />