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<br />. <br /> <br />PLAN OF DEVELOPMENT <br /> <br />Three alternate plans of development have been identified for <br />rehabilitation of Rio Grande Dam. The, three alternates are described <br />below: <br /> <br />Alternate A - Outlet works repair, dam monitoring program, <br />and flood warning program, combined with a <br />reservoir storage restriction, enabling the <br />dam and spillway to safely pass the one-half <br />probable maximum flood. <br /> <br />Alternate B - Outlet works repair, flood warning program, and <br />enlargement of the dam so that the one-half <br />probable maximum flood can be safely passed. <br /> <br />. <br /> <br />Alternate C - Outlet works repair, extension of the outlet <br /> <br /> <br />works tunnel, spillway enlargement, and dam <br /> <br /> <br />enlargement so that the probable maximum flood <br /> <br /> <br />can be safely passed. <br /> <br />Each of the alternates would also include repair of the outlet works <br />and a program for monitoring the stability of the north abutment. <br />The plan of development for each alternate is described in greater <br />detail below. <br /> <br />Outlet Works Repair <br />Leakage through both sets of closed outlet works gates was <br />observed to be roughly five cfs in March, 1980 when the reservoir <br />-..------ <br />water level was at elevation 9438 (gage 80). Leakage in July, 1981 <br />through the upstream gates only was estimated to be about 4.3 cfs, <br />-'-,-......-. ._------- <br />with a reservoir water level at elevation 9401.5 (gage 43.5). On <br />both occasions water was primarily leaking around the lower sides of <br />the gates, indicating that the brass seals along the gate guides <br />should be replaced. During the March, 1980 inspection, it was observed <br /> <br />. <br /> <br />-41- <br />