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<br />' San Luis Project -Phase II Raise I Expansion Cotutruction Statue Report <br />homogeneous source does not exist. Average material properties of the borrow are of a silty <br />sand in general compliance with the Type 2 material specification. Discrete zones of the <br />borrow, however, are of sandy silt and of gravelly sand and require blending to produce a more <br />uniform material. The resulting material is generally free of material in excess of the #4 U.S. <br />sieve size and therefore tends to reflect higher sand and silt percentage relative to the Type 2 <br />' material specifications. The acceptable gradations for this material type have been slightly <br />modified to allow some variability of the mid-range gradations. The maximum allowable <br />' percent passing the #200 sieve remains at 35 percent. <br />None of the liner cover material placed by the earthwork contractor has been gpproved to date. <br />The contractor's borrow procedures and material handling have precluded conformance testing <br />of liner cover/drainage blanket material prior to placement on the liner. Therefore, a <br />conformance testing program consisting of 1 sample for every tfi acre of liner has been adopted <br />' prior to final acceptance of all liner cover which has been placed to date, The contractors liner <br />cover borrow and placement procedures have been modified to allow removal of oversize and <br />conformance testing prior to material removal from the borrow sources. <br />4.4.3 Liner Sub-base <br />Material Type 3 is being utilized for liner sub-base/clay liner component as specified. <br />' Placement of this material as specified, 95 percent maximum dry density at plus 3 percent to <br />minus 2 percent of optimum moisture content, resulted in an acceptable final product. However, <br />wet weather during August and September frequently resulted in an overly wet surface on <br />' previously approved areas which was then unsuitable for deployment of the geomembrane liner <br />until the material was dried back. This was causing considerable construction delays. <br />Testing of the material using actual field procedures indicated that the speciffied density and <br />' permeability requirements could be met if the material were placed drier than originally <br />specified. Placed at 4-6 percent dry of optimum moisture content, the material also resulted in <br />a firm surface which was smoother than when compacted as originally specified and would <br />' promote run-off to a greater extent. Subsequent rains did not render the surface of the material <br />suitable for liner deployment as frequently as before this procedure was implemented, therefore <br />' this procedure has been adopted for all subsequent construction <br />October, 1993 g SRK Project No. 14725 <br />