Where should the stone extend during the installation of a sediment dam trap?

The correct choice indicates that the stone should extend downstream past the toe of the embankment during the installation of a sediment dam trap. This design is essential for several reasons related to effective sediment control and water management.

Extending the stone downstream past the toe of the embankment helps to ensure that any water flowing over or around the dam does not create erosion or sediment transport issues downstream. By providing this additional coverage, the stone acts as a protective barrier that helps to filter out sediment before it can reach larger water bodies. This is particularly important in preventing sediment pollution and maintaining water quality.

The placement of stone downstream also plays a critical role in stabilizing the embankment itself. It prevents the erosion that can occur when water flows over the edge or around the dam, which could lead to failure of the sediment trap. Properly extending the stone creates a more robust structure that can handle hydrological forces more effectively.

In contrast, options related to extending the stone only upstream, directly at the toe, or only at the crest do not provide the same level of protection and functionality in sediment control, which is crucial for the effective operation of a sediment dam trap.