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emergency spillway crest would be set at 10,393 to allow an additional foot of ponding above the <br />elevation recommended in the 1987 Feasibility Study. This would allow a total storage volume <br />of about 222 acre-feet assuming that sedimentation has not reduced the reservoir's original <br />storage volume of 210 acre-feet at elevation 10,392. A spillway configuration utilizing a 45 feet. <br />bottom width and 2H:1 V side slopes was required for this alternative. These improvements <br />i��ould allow the spillway to convey 1/2 of the PMF with about 1.4 feet of freeboard. <br />Alternative No. 2 is similar to Alternative No. 1 except that the dam embankment would be <br />raised about 8.5 feet to an elevation of 10,407 and the existing spillway would be modified to <br />convey 1/2 of the PMF. The embankment would be extended along the downstream slope at <br />2.25H:1 V to provide additional stability. Figure 3 presents the embankment modifications for <br />both alternatives. T'he proposed emergency spillway crest would be set at 10,394 to allow an <br />additional 2 two feet of ponding above the elevation recommended in the 1987 Feasibility Study. <br />This would allow a total storage volume of about 240 acre-feet assuming that sedimentation has <br />not reduced the reservoir's original storage volume of 210 acre-feet at elevation 10,392. A <br />spillway configuration utilizing a 45 feet. bottom width and 2H:1 V side slopes was required for <br />this alternative. These improvements would allow the spillway to convey 1/2 of the PMF with <br />about 1.4 feet of freeboazd. <br />Other improvements common to both aternatives include installing riprap on the spillway <br />embankments and along the downstream face of the dam. A concrete grade beam will be <br />provided across the spillway crest to protect against erosion when the spillway operates. The <br />outlet pipe will need to be extended downstream to accommodate the extension of the dam <br />embankment and a footbridge will be installed across the spillway to provide access to the dam. <br />The results of the analysis indicate that both alternatives are feasible. Table 2 presents the <br />critical information for both alternatives as well as the alternative recommended in the 1987 <br />Feasibiliiy Study. <br />Table 2. Results of Analysis <br />Alternative <br />1987 Recommendation <br />1 Raise spillway one additional foot <br />2 Raise spillway two additional feet <br />Maximum <br />Spillway Storage Top of Dam <br />Elevation (acre-feet) Elevation <br />10,392 210 10,40�k � <br />10,393 222 10,406 <br />10,394 240 10,407 <br />6 <br />Approz. <br />Project <br />_� <br />$769,000 `��5� <br />$834,000 <br />