An overflow ogee crest for a spillway is to discharge 20,000 cfs. the upstream face of the crest is sloped 1: 1 and a bridge is to span the crest. flow over the spillway is to be controlled by a series of tainter gates. bridge piers 18-in wide (pier contraction kp = 0.05) with rounded noses are to be provided to support the gates. the bridge spans (center to center of piers) are not to exceed 30 ft. the maximum expected head he = 10 ft. neglect velocity of approach head. the distance from the spillway crest to the reservoir bottom p = 18 ft. the abutment coefficient ka = 0.10. assume that your design head is equal to the maximum expected head. determine: (ans: l’ = 169.4-ft,) (a) the crest length required (b) the number of tainter gates to be used (c) the width of each gate