What material is primarily used to construct sediment dam trap outlets or spillways?

The construction of sediment dam trap outlets or spillways generally incorporates materials that can effectively manage and control the flow of water while providing stability and integrity to the structure. The use of No. 5 washed stone and class B riprap aggregate is particularly suitable for this purpose.

No. 5 washed stone is often utilized in various applications due to its durable and high-permeability characteristics, allowing for efficient drainage while reducing erosion around the outlet areas. Class B riprap aggregate serves as a protective layer that can absorb and dissipate the energy of water flow, which is critical in preventing scour and erosion at spillways. These materials work together to ensure that the sediment trap functions effectively without compromising the surrounding environment.

Other materials mentioned in the options may not offer the same level of effectiveness or suitability for this specific application.