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<br />.' <br /> <br />., <br /> <br />l",.; " .., <br />~jU. <br /> <br />Suitable qu:mtities of pervious to semi-pervious materisl ma)" be available along <br />the Platte RIver within 2 or 3 miles upstream of the dam.. The area for borrow of per- <br />vious materi:1l would be completely Inundated by the reservoir waters. <br />The borrow sources for impervious materlo.1 are In three areas and total nearly <br />1000 acres. One 260 acre source would be Immediately upstream of the dam and north <br />of the river and would be entirely below the top of conservation pool. It would probably <br />be used to supply most of the impervIous materIal for the dam. <br />The second source of impervious material Is the top of the bluff that forms the <br />north abutment of the dam. ThIs area Is the proposed location of the a\L...:i1iary spillway. <br />Material. excavated for the spillway and some addttional borrow material from this site <br />will be used for dam emb::mkment. <br /> <br />The last designated earthfill borrow area is located within 1 mile do....nstream of <br />the dam and southwest of State Highway 144. This 400 acre source could be used for <br />the south portiOD of the dam and embankment for the railroad relocation. The area <br />would be revegetated after construction. <br />The above designated borrow areas represent a V'olwne of material that is nearly <br />three times the actual volume needed. Cons[dering the required quality of materral for <br />each use, economic haul distances, and the contractor's proposed method of operation. <br />the Bureau would determine the e.'\.-tent each borrow area may be utUtzed. Most of the <br />material for the dam could probably be obtained from within the reservoir. However, <br />fill for the railroad embankment and possibly some materi:1l for the dam would be ob- <br />tained from the downstream areas. Borrow areus may be subject to change to locate <br />them withlI1 the reservoir boundaries when additlonallnformation becomes available. <br />Coarse aggregate materi.alis scarce in the Narrows Unit locality, and it will <br />most likely be shipped in from some area close to the mountains such as near Greeley, <br />Golden, or Denver, Colorado. Fine concrete aggregate material is ~vallable in the <br />.flood plain of the South Platte River upstream and downstream from the damsite. <br />Riprap is not locally available and would probably be shipped from some of the <br />e:([sting rock quarries west of Denver, Colorado. Should soH cement be used in lieu of <br />,-::a.. riprap for slope protection on the dam, the requlremer:.t for riprap will be considerably <br />less. Adequate quantities of material for soil cement appear to be available within the <br /> <br />4, <br /> <br />"' <br />