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-4 Mr. Horton Page 3 majority of the soils described by Kleinfelder in the borrow area do not meet the Chapter 15 requirements and are not acceptable. The closure plan states that the mixture of the minor amount of clay with other native soils will result in a permeability which meets the I x 10-6 cm/sec requirement. As proof that the mixture will meet the permeability requirement, the closure plan relies on the 1987 Kleinfelder report which states that a 10®6 cm/sec permeability can be achieved by proper blending of the soils. While proper blending may ach-4 ---,.,-- the required permeability, there is no discussion of what proper blending is. At a minimum, it would appear that proper blending would consist of removal of much of the high permeability soils. We are concerned that there would not be a sufficient volume of the resulting acceptable mixture to complete the low permeability layer. No details are given concerning the process of mixing soils. We have seen clay soils mixed at a landfill liner site where the mixture was not acceptable due to the clay' s tendency to form small clods when mixed with other soils. The inability of the contractor to evenly disperse the clay in other soils resulted in a large increase in construction costs. The unacceptable process used large rototiller type equipment. Details of the Harney Lane mixing process must be given. The CQA testing protocol states that additional material will be needed from an area just south and west of the source area. The closure plan does not discuss this additional material in the operation work or cost estimates sections. 14 CCR 17774 (e) states that "Analysis of the earthen materials should be performed prior to their placement onto the final cover. . . " Therefore, the blended soil mixture for the clay cover must be determined and tested to see if it meets the performance goals of Chapter 15 prior to use of the soil mixture as a clay cover. These activities should occur in the construction and testing of the test pad. The operator should recognize that lab permeabilities are typically ten to one hundred times lower than field permeabilities. If this observation holds for the proposed soil mixture, it will fail to meet the Chapter 15 permeability requirements. 11. ' The operator has not conducted sufficient soil tests to identify the density and moisture conditions necessary during construction to achieve the required permeability. There is no discussion in the closure plan of key