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File No. 20-3514-01 k%j KLEINFEL DER <br /> September 11, 1991 <br /> Based on the design method presented in Topic 608 of the Caltrans <br /> Highway Design Manual , a design R-Value of 50 and assumed traffic <br /> indices, we recommend the following pavement sections: <br /> Minimum Minimum <br /> Traffic Thickness of Thickness of <br /> Pavement Area Index Asphalt Concrete Aggregate Base <br /> Cul-de-Sac 4 . 0 2" 4" <br /> 4 . 5 2" 4" <br /> 5 . 0 2" 4-1/2" <br /> The subgrade soils over which these paving materials are to be <br /> placed should be compacted to minimum depths of 6 inches for <br /> existing soils and 12 inches for Engineered Fill to a minimum of <br /> 95 percent of the ASTM D-1557 maximum dry density, at near optimum <br /> y moisture content. In addition, it is recommended that all <br /> pavements conform to the following criteria: <br /> 1. All trench backfills, including utility and sprinkler <br /> lines, should be properly placed and adequately <br /> compacted to provide a stable subgrade. <br /> 2 . An adequate drainage system should be provided to <br /> prevent surface water or subsurface seepage from <br /> saturating the subgrade soil. <br /> 3 . The aggregate base should be compacted to a minimum of <br /> 95 percent of the maximum dry density as determined by <br /> the ASTM D-1557 test method. <br /> 4 . The aggregate base and asphalt concrete materials <br /> should conform to the specifications stated in <br /> Sections 26 and 39, respectively, of the State of <br /> California Standard Specifications, latest edition. <br /> 5 . The pavement section recommendations presented assume <br /> that periodic maintenance of pavements will be done, <br /> including sealing of cracks. <br /> 6 . All curbs surrounding landscape areas should be <br /> embedded at least 6 inches below subgrade to minimize <br /> the movement of moisture beneath pavements. <br /> Copyright 1991 KLeinfelder, Inc. Page 8 of 13 <br />