Laserfiche WebLink
<br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />Chapter IV - Formulation of Alternatives <br /> <br />Several alternatives were developed to meet the project purpose of rehabilitating Horseshoe Dam <br />No.2 Outlet Works. The alternatives included three (3) structural and one (I) non-structural or the "no- <br />action". Alternatives were formulated to address the problems described in Chapter I of the report. <br /> <br />The main differences between the alternatives is the gating system, as described below: <br /> <br />A. Alternative 1 - Upstream Gate <br /> <br />As shown in Figure IV -1, the first alternative consists of a 42-inch sluice gate located on the <br />upstream face of the dam. The gate stem guide would be encased in oil to prevent freezing. The gate <br />would be controlled from the crest of the dam. The gate controls would be housed in a concrete gate <br />box located on the dam crest. The gate, controls the flow into a 42-inch steel sleeved pipe. The steel <br />pipe would be cement mortar lined to prevent corrosion of the pipe surface. The pipe would be <br />extended downstream past the gate chamber and connected to the downstream section of the outlet <br />works. The downstream section of the 48-inch CMP outlet works was sleeved in 1985 with a 42-inch <br />steel pipe. The existing 72-inch CMP gate chamber would then be filled with a pervious material and <br />capped with concrete. The new gate control house would then be constructed on the capped gate <br />chamber. <br /> <br />B. Alternative 2 - Gate Chamber <br /> <br />Figure IV-2 shows that the second alternative consists of lining the existing gate chamber with <br />concrete and controlling the flow with two 42-inch sluice gates; one mounted upstream and one <br />mounted downstream in the gate chamber. The outlet pipe would consist of a 42-inch mortar-lined steel <br />sleeve pipe. The steel sleeved pipe would be extended down to the upstream of the lined gate chamber. <br />The pipe upstream of the gate chamber will be pressurized, once the outlet works is closed. A gate <br />house will be constructed on top of the dam to project the operators and to gain access to gates. <br /> <br /> <br />Horseshoe Dam NO.2 Outlet Works Study <br /> <br />19 <br /> <br />BOYLE <br />