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kn <br /> File No. 20-1008-49.001 KLEINFELDER <br /> July 8, 1993 <br /> CONCLUSIONS <br /> Based on the results of our laboratory and SDRI permeabilities, it appears that the SP/SM test <br /> pad did not meet permeability specifications, although the SDRI test came very close to passing <br /> (1.8 x 10'cm/sec). Due to the test results and the limited amount of clean sands in the borrow <br /> area, San Joaquin County has elected not to use this material in the future construction of the <br /> low permeability barrier layer. <br /> Laboratory permeability results indicate that both the ML and SM test pads satisfy barrier <br /> permeability requirements. Our experience has been that SDRI test results are typically less <br /> than lab permeabilities. The SDRI test for this project was approximately five times less than <br /> the lab permeability for the SP/SM test pad. The lab permeabilities for the ML& SM test pads <br /> were both satisfactory. Because of these lab results, it is our opinion that an SDRI test on <br /> either of these two test pads would most likely indicate an even lower permeability. For this <br /> reason, we do not recommend further SDRI testing. <br /> We recommend the following procedure be used for barrier construction. Approximately 12 <br /> inches in loose thickness.of SM or ML material shall be placed on the foundation layer. We <br /> believe one reason for the failure of the SP/SMtest pad was the "dilution" of the Ione Clay <br /> because of excessive_ mixing depth. One truck load (26.02 tons) of 10$ cm/sec Ione clay shall <br /> be spread uniformly over an area of 1725 square feet per load. Two 8-inch depth passes with <br /> a CAT RR250, or equivalent, shall be made to initially break the clay down. A minimum of <br /> three final passes at a depth of 15 inches (the last pass may be used to add water) shall be made <br /> for final mixing. Compaction shall be performed by a CAT 825C sheepsfoot compactor, or <br /> equivalent with a minimum of ten passes. Testing shall be in accordance with Tables 7-1 <br /> through 7-4 of the Construction Quality Assurance Plan. <br /> GSM:sh <br /> Copyright 1993 Kleinfelder, Inc. Page 7 of 7 <br />