Debris Spillway and Chute for Millers Ferry Powerhouse, Alabama River, Alabama: Hydraulic Model Investigation

A 125-scale model of the Millers Ferry Lock and Dam, Alabama River, Alabama, reproduced a 24-ft-wide by 170-ft-long ogee spillway and existing powerhouse, 200 ft of the approach immediately upstream of the spillway crest, and 600 ft of exit channel. The hydraulic design of the debris spillway was evaluated. Model tests consisted of observing flow conditions throughout the structure, determining how effectively debris was being passed through the structure, and determining if scour of the riprap protection downstream occurred. A horizontal apron terminated by a curved right sidewall diverted flow into the deeper tailwater area and provided needed energy dissipation for passage of debris through the chute spillway. It was determined that the debris spillway would operate efficiently without causing unacceptable flow conditions and scour downstream from the spillway chute with tailwater el 32.050.0. Operation of the debris spillway would have to be suspended at tailwaters greater than el 50.0, and waterlogged debris and debris larger than 50 ft would have to be physically removed.