Red River Waterway, Lock and Dam No.3. Report 4, Stilling basin and riprap requirements : spillway hydraulic model study

Tests were conducted on a 1:50-scale model of Lock and Dam No. 3, Red River Waterway, to develop a satisfactory energy dissipator and a stable riprap plan. The spillway consists of 315-ft-long overflow weirs and six 42-ft-high by 60-ft-wide tainter gates. The 84-ft-wide by 785-ft-long lock will be located on the left river bank looking downstream and will have a maximum lift of 31 ft. The recommended stilling basin provides adequate energy dissipation for normal water flow and for a single gate fully opened with minimum tailwater. Stable riprap plans were developed for the upstream and downstream areas adjacent to the structure for both normal flows and flow rate and for a single gate conditions. Pressures measured on the spillway crest were sufficiently high to prevent cavitation problems on the downstream ace of the crest. Water-surface profiles were measured for a wide range of conditions and are compared to computed spillway rating curves.