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<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 />SECTION III <br />PRELIMINARY DESIGN FOR EMERGENCY SPILLWAY <br /> <br />In the evaluation of possible alternatives for the Kern Reservoir Emergency <br />Spillway, the following criteria were ~sed: <br /> <br />-Ability to pass probable maximum precipitation flood as determined <br />by the Corps of Engineers report dated July, 1978. (10,400 cfs) <br /> <br />-Route the flood waters in the same general direction they would go <br />if the reservoir did not exist. <br /> <br />-Minimize velocities over the spillway as much as possible to de- <br />crease potential negative downstream effects. <br /> <br />-Spillway improvements should be cost effective and positive with <br />respect to a Benefit/Cost Analysis. <br /> <br />During the preliminary stages of this ~tudy, it became apparent that a conven- <br />tional emergency spillway would not be applicable for the Kern situation. <br />Realizing the fact that the embankment which is adjacent to the Town of Windsor <br />averages only five (5) feet in height qnd that during a PMP flood the Town and <br />all surrounding areas would more than likely already be inundated, it seemed <br />feasible that a portion of the existing embankment should be upgraded and uti- <br />lized as the emergency spillway for th~ reservoir. <br /> <br />As can be seen on Exhibit A, the probable maximum flood would traverse a course <br />in the general direction and location shown. To allow the flood waters to pro- <br />ceed in approximately the same manner without causing a failure of the reservoir <br />dikes on the south side of the lake, significant erosion protection is required. <br />This can be accomplished in several ways. A cross-section of the method which <br />is being recommended by this report is shown on Exhibit C. <br /> <br />The required length of spillway was calculated by utilizing procedure~ illus- <br />trated in Bureau of Reclamations Publication, Design of Small Dams. The minimum <br />length of spillway assuming the height of water above the crest of the dike to <br />be two feet (2') with a velocity of 4.16 feet per second, is 1250 L.F. Exhibit <br />B shows the proposed location of the spillway portions of the embankment. The <br />preliminary elevation of the crest has been set at 4796.0. However, the final <br />