Coastal and Floodplain Construction Inspector's Practice Exam

What is a requirement for breakaway walls in a flood hazard area subject to high velocity waves?

1. Must support at least 30 psf of lateral load

2. Must be designed to resist flotation and collapse

3. Must have no resistance at all

4. Must be anchored to the foundation

The correct answer is: Must be designed to resist flotation and collapse

In a flood hazard area that is subject to high-velocity waves, breakaway walls are designed with particular requirements to ensure they function correctly under extreme conditions. The requirement that emphasizes being designed to resist flotation and collapse is central to maintaining structural integrity and ensuring safety. This design consideration is critical because breakaway walls are intended to provide minimal interference with floodwaters, allowing them to wash away without significantly impacting the primary structure above. However, they must still be capable of remaining in place under certain loads, particularly during surge events. Resist flotation prevents the walls from being lifted away by buoyant forces, while resisting collapse ensures they can endure hydrostatic and hydrodynamic pressures until they are broken away by extreme water forces, thus preventing damage to the elevated structure above. This understanding of the need for breakaway walls to maintain their effectiveness during flooding is why the correct answer revolves around their design to resist flotation and collapse without compromising the overall safety of the building. Thus, it is crucial that these walls are engineered to meet stringent criteria that align with their purpose in a high-velocity flood environment.