Little River Drainage District - Spillway Repairs

Cape Girardeau, MO

Caney Creek Basin

The Problem: The emergency spillway was activated during the 2011 flood.  Spillway velocities exceeded 25fps, significant souring/erosion of bedrock and riprap occurred below concrete spillway, large flows flanked the spillway and eroded adjacent bank.

Inspection:  Klingner’s inspection identified issues of concrete repairs and slope protection.  In addition, that significant energy dissipation was needed.

Our Solution: Our solution was to backfill and cap the scour holes with reinforced concrete and to install four check dams with low flow orifices which lowered the anticipated flow velocities below 6fps.  This project was reviewed and accepted by the Missouri Department of Natural Resources.

 

Jenkin's Basin

The Problem: The originally designed earthern spillway could not withstand overtopping velocities.  This presented potential cutting of the embankment slope.

Our Solution: Our solution was to finish grade and line with reinforced concrete starting at the inlet and continuing along the back slope to a point where flow velocities were low enough to transition to riprap protection.  A stilling pool was designed within the toe, to induce a hydraulic jump and dissipate energy and scouring potential.  This spillway, like Caney, was modeled to determine design performance.