The maximum spacing between check dams should ensure the bottom of the upstream dam is at the same elevation as what part of the downstream dam?

The maximum spacing between check dams is designed to maintain effective control of sediment and water flow within a construction site or disturbed land. When determining the spacing, it’s crucial that the bottom of the upstream check dam is at the same elevation as the bottom of the downstream check dam. This ensures that water flowing from one dam to the next will not create an erosion risk or allow sediment-laden water to bypass treatment provided by the downstream structure.

When the bottoms of the check dams are aligned, it creates a step-like barrier that slows down the velocity of the water as it moves downstream. This slowing of water allows for sediment to settle out rather than being transported further downstream, which is vital for controlling erosion and sedimentation in stormwater management practices. Aligning the dam bottoms supports the intended function of the check dams in removing sediment from water and preventing further erosion in the area, thereby achieving the goals of effective stormwater management.