In dry swale design, what type of material is typically used for the energy dissipater at the downstream toe?

The correct choice for the material typically used for the energy dissipater at the downstream toe of a dry swale design is concrete. Concrete is commonly selected due to its durability and effectiveness in handling high-energy flows generated by stormwater runoff.

Energy dissipaters are essential in stormwater management systems as they help to reduce the velocity of water exiting the swale, thereby minimizing erosion and downstream sediment transport. Concrete structures can withstand the forces of rapidly flowing water while ensuring the stability of the swale and its surrounding infrastructure. Moreover, concrete is straightforward to shape and can be designed to direct water flow effectively, making it an ideal choice for this application.

While other materials like wood or plastic could potentially be used in different contexts, they do not offer the same level of durability and structural integrity necessary for an energy dissipater subjected to the forces of stormwater runoff. Synthetic fabrics serve a different purpose in stormwater management, often related to filtration and stabilization in other types of systems, but are not suitable for use as energy dissipaters where robust physical structures are required.