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KLEINFELDER <br /> File No. 24-2206-01.A06 <br /> January 2, 1991 <br /> Mixed Clay Liner Using Mixing of Nearby Borrow <br /> A second alternative would be to mix native soil with clays from <br /> off-site sources. It is our experience that clay deposits such as <br /> those encountered near Ione, California can significantly reduce <br /> the coefficient of permeability. A sample from the Foothill <br /> Landfill (B-7-20) was mixed with 15 percent Ione clay and yielded <br /> a permeability of 1. 7 Y 10-� cm/sec. This result, vinic- aces not <br /> meet the 1 Y 10-h cm/sec requirement for Chapter 15 19clav" liners, <br /> indicated that a greater percentage of clay or a higher degree of <br /> compaction may be needed ,to obtain a certifiable liner. The actual <br /> amount is difficult to estimate and would need tc be evaluated <br /> based on further testing. We note that clays such as those <br /> encountered in Ione, California have been successfully mixed with <br /> silts and sands with permeabilities similar to those at Foothill <br /> Landfill, achieving permeabilities of less than. 1x10_b c. /sec. <br /> Chemical Additives <br /> Chemical additives have also been used on similar silts and clays <br /> and have achieved slightly lower permeabilities than native <br /> materials. We note that although the chemical additives are often <br /> cost-effective, to our knowledge, there have yet to be . any <br /> landfills in San Joaquin Valley which have been lined with native <br /> materials mixed with chemical additives. For this reason, we <br /> anticipate that the regulatory requirements to obtain approval may <br /> be extensive. <br /> LIMITATIONS <br /> 1. The conclusions and recommendations of this report are <br /> for design purposes for the proposed Foothill Landfill <br /> Expansion, Phase I project as described in the text of <br /> Copyright 1991 Kleinfelder, Inc. 8 <br />