Single-Sided Flashboard Risers have unique constraints that must be considered for successful installations. Floating, Leaning and Sliding are important design factors that are often overlooked when installing single-sided flashboard riser structures. 

Floating     Single-sided box-type flashboard inlet structures want to “float” when the water is blocked and the inlet box is dry.   

Leaning and Sliding  The weight of soil behind tall structures can push on the back causing the structure to lean forward and slide away from the bank.    These factors are magnified in loose and soggy soil conditions where the soil slumps excessively.

Schematic diagrams of the forces acting on the riser box:

All similar structure designs will encounter these forces.   The structures will resist floating, leaning and sliding to some degree through a combination of their weight and soil trapped against the sides and the pipe flange.  These forces can become a significant problem on large and tall boxes.

Our structures have extended bases and provisions for pinning to help support the box and relieve stress on the pipe connection.

We offer support frames for tall boxes.   When properly backfilled, these frames will control the floating forces and significantly reduce the tendency for the boxes to lean or slide.    Support frames are supplied with all structures 48 inches and taller.    The frames are easily  assembled on site.