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<br />Monument Lake Dam Feasibility Study <br /> <br />53 <br /> <br />.- <br />1i30'r'UJ <br /> <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />Chapter V - Evaluation of AJternatives <br /> <br />C.2 Embankment alternatives <br /> <br />A feasibility level probable cost estimate was performed for each of the two embankment <br /> <br /> <br />alternatives. Major construction work items were identified, and unit prices and quantities were <br /> <br />estimated for these items. For imported materials, commercial sand and gravel sources were <br /> <br /> <br />contacted to obtain costs to purchase these materials. The following assumptions were made: <br /> <br />. The cost item "Mobilization/Demobilization" is identified to cover the costs of <br /> <br /> <br />mobilization and demobilization of equipment, temporary construction facilities, and <br /> <br /> <br />bonds and insurance. It was also assumed that there is little total other overhead <br /> <br /> <br />construction costs such as constructi<m supervisory personnel. For this type of <br /> <br /> <br />construction, mob/demob typically r<lnges from 5 to 15 percent of the total <br /> <br />construction cost. Ten (10) percent was assumed for this cost estimate. <br /> <br />. Foundation dewatering for the new drain construction can be accomplished by <br /> <br /> <br />pumping from sump pits. The foundation dewatering cost presented does not include <br /> <br /> <br />the dewatering cost for the new outlet works and spillway channel erosion protection <br /> <br /> <br />work. <br /> <br />. The existing riprap on the upstream ~Iope above elevation 6920 would be excavated, <br />stockpiled, and reused. It was assumed the thickness of the existing riprap is <br />approximately 18 inches. It was also assumed that there is little to no riprap bedding <br />to be salvaged. Additional riprap would be required to build the new riprap layer to a <br />thickness of 2 feet. <br /> <br />. Rock excavation would be required in the left abutment for the construction of the <br /> <br /> <br />new training wall extension. The weak sandstone bedrock is assumed to be rippable. <br /> <br />Excavation rock materials are not suitable as fill, and will be disposed of on site. <br /> <br />. Excavated fill materials from the existing embankment will be re-used as new <br /> <br /> <br />embankment fill. All excess fill not used will be dispose of on site. <br />