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<br />1 <br />' September 28, 1998 <br />A. Fine-Grained Cushion Layer <br />The fine-grained cushion layer shall consist of materials selected for their lack of <br />angular or sharp particles or other constituents which might damage the <br />Geomembrane Clay Liner (GCL). The cushion layer may be constructed with <br />' coarse tailings material. The Contractor shall place, a minimum of 4 inches of fine- <br />grained cushion layer in such a manner as to avoid damage to the GCL liner where <br />needed.. <br />Due to the intended method of use and placement, the cushion layer will be rolled <br />with a small smooth drum roller or rubber tired equipment, as directed by the <br />engineer. There are no other requirements for this material and in-place testing is <br />not necessary. <br />B. Working Surface <br />' The initial layer of fill placed at the downstream toe of the embankment and over the <br />existing tailings surface outside the limits of the existing embankment, function as <br />' the working surface. This layer may be placed in a single lift having sufficient <br />thickness to support hauling and placing equipment intended for use in the <br />construction of the embankment. <br />' The working surface placed over the geogrid on the existing tailings surface and <br />developed beneath the upstream footprint of the embankment raise shall be clear <br />' of all vegetation, debris and other deleterious material prior to the placement of the <br />geogrid. <br />' C. Embankment Material <br />Material for the embankment construction shall consist of material excavated from <br />the pond expansion. All materials shall be free from deleterious substances such <br />as rubbish, organics, perishable or other unsuitable materials, and will be approved <br />by the Engineer at the source. <br />Lift layers shall be placed and spread on the embankment in layers which do not <br />exceed 6 inches in thickness after compaction. The material shall be moisture <br />conditioned to a moisture content of two percent below to two percent above <br />optimum moisture, or as directed by the engineer, spread and compacted. The <br />Contractor shall spread, level, and compact the material to ninety percent (90%) of <br />Modified Density (ASTM D 1557). <br />Cobbles and boulders which are large enough to interfere with the construction of <br />the designated lift thickness shall be removed, or at the Owners agreement, raked <br />' towards the downstream face of the embankment, and deposited on the <br />embankment face. <br />' Earthwork <br />' J:\5461\SPECSFNL.WPD (]2200-.3 <br />