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<br />2.0 Alternatives <br /> <br />2.1 Alternatives Eliminated from Further Consideration <br /> <br />Three additional alternatives were considered and eliminated from <br />consideration based on the following information. <br /> <br />2.1.1 Stone/Masonry Gravity Wall. This alternative US':lS existing rock in the <br />area as well as cement. Due to the climate of the region the structure would be <br />subject to freezing and thawing. These conditions could reduce the structural <br />integrity of the wall. <br /> <br />2.1.2 Steel Crib Wall. This alternative is a steel crib wall filled with on site <br />rocks. In order to fit the steel wall to the site, a weat deal of field fitting of steel <br />components and fabrication to conform to the existing terrain would be required. <br />This alternative would be both expensive and difficult to construct due to the <br />terrain. <br /> <br />2.1.3 Rock-Filled Gabions. This alternative is rock-filled gabions. A gabion <br />is a cage filled with rocks. The gabions require a level foundation area, which <br />would be difficult without exterior rock excavation or levelin~1 with mortar or <br />concrete. This alternative would be both expensive and difficult to construct due <br />to the terrain. <br /> <br />2.2 No Action <br /> <br />The No Action Alternative describes the conditions without Corps <br />rehabilitation and provides the basis for the environmental evaluation in Section <br />3.0. Under this alternative, no Federal action would be taken to rehabilitate the <br />streambank on Skyrocket Creek. The existing diversion woulld continue to <br />deteriorate, and the risk of a debris flow affecting the downstream facilities would <br />remain high. <br /> <br />2.3 Reinforced Concrete Wall <br /> <br />The Corps proposes to remove the current diversion and replace it with a <br />reinforced concrete wall keyed and doweled into the existing bedrock. The work <br />would be accomplished in three steps and take about 3 weeks to complete. Work <br />will occur in August or September when the stream channel lis dry. <br /> <br />Step 1. Mobilization - This step would involve preparation and movement of <br />construction equipment and materials to the project site. A helicopter would be <br />needed to convey equipment to the work site. A staging area for the helicopter <br /> <br />4 <br />