If a temporary stone/riprap sediment trap receives four acres of drainage, what should the width of its weir be?

The width of the weir in a temporary stone/riprap sediment trap is determined based on the amount of drainage area that flows into it. For a sediment trap receiving four acres of drainage, design guidelines often recommend a specific width for the weir to ensure adequate sediment removal while preventing overflow or failure of the trap.

In Maryland, as per erosion and sediment control practices, the standard design is that the weir width should be approximately four feet per acre of contributing drainage area. Therefore, for four acres, the calculation would typically yield a weir width of about 16 feet. This width allows for sufficient flow capacity to manage runoff effectively, minimizing sediment transport and maximizing retention within the trap.

By ensuring that the weir is appropriately sized to handle the drainage from four acres, the design effectively reduces the risk of erosion and sedimentation in downstream water bodies, aligning with sediment control practices focused on protecting water quality.