Spillway and Outlet Works, East Branch Reservoir, Clarion River, Pennsylvania: Model Investigation
Abstract
Model investigations of the spillway and outlet works for the East Branch Reservoir, Clarion River, Pennsylvania, were conducted to insure satisfactory over-all hydraulic functioning of these structures. Particular attention was given to development of a dispersal bucket at the lower end of the side-channel spillway and to the performance of the slide gates, tunnel, and stilling basin of the outlet works. Three models were used in the studies: a 1:50-scale model of the side-channel spillway, a 1:25-scale model of the outlet works, and a 1:12-scale model of one slide gate. The spillway dispersal bucket was required not only to dissipate effectively the energy of flow, but also, because of certain terrain features of the exit area immediately downstream, to insure that the left bank would not be subjected to excessive scouring action and that flow would not impinge directly upon the right bank. Several designs tested for the spillway dispersal bucket indicated satisfactory dissipation of energy of flow. It was found, however, that a bucket with the following elements gave the most desirable distribution of flow: a curved left wall raised 10 ft above the height of the end sill, and an end sill with upstream face on a 1-on-1 slope and with the straight leading edge forming an angle of 1 on 5 with the center line of the chute. It also was determined that the spillway coefficient could be increased, without producing dangerous negative pressures, by shaping the weir to conform to the nappe of a 12-ft head, although the design flood produced a 17-ft head on the weir. This increase in the discharge coefficient permitted a 10-ft reduction in the length of the spillway crest. Tests of the intake structure and tunnel indicated satisfactory operating conditions for all flows, except with one gate completely closed and the other open approximately 10 ft.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1951
- Accession Number
- ADA637739