BMP Blast: Check Dams

Fast moving water can cause a LOT of damage! Many problems can arise from water flowing at a high velocity. This is especially the case when talking about a high flow rate in concentrated areas such as ditches or swales. Erosion is an issue that can result from the high velocities that may occur in ditches or swales, and so it is important to find ways to mitigate the erosion in the best way possible. Check dams are a great option that can be installed in ditches and swales to decrease the water velocity and in some cases keep sediment from washing downstream.

​Check dams are constructed structures built up as a wall in a flow path that serves the purpose of slowing down water velocity. Many check dams consist of 4–8-inch stone and are no higher than 3 feet tall and are constructed along the width of the swale/ditch. Check dams can also be constructed of material such as compost filter sock. As mentioned above, check dams can also serve the purpose of keeping sediment from washing downstream. However, not all types of check dams are good for sediment control. Rock check dams are an effective way to slow down velocity and prevent erosion, however, rock is not an effective method to keep sediment from washing away due to the pore space in the material that sediment can wash right through. Filter socks are designed to keep sediment from washing downstream, and so if the goal is to slow the velocity of the water AND keep sediment in, then a filter sock check dam might be the best option.  

Maintenance Considerations:

• Per the Rainwater and Land Development manual, once sediment has built up to one-half the original height of the check dam, the sediment should be removed.
• Removal of the check dam should occur once earth disturbance has ended and the upland area has been stabilized. Once the check dam has been removed, the area should be graded and seeded to match the surrounding area per the design.
• Routine inspections are also a great way to ensure the check dam is working effectively.

 
For more information on the design criteria and specifications about check dams, please visit the OEPA Rainwater and Land Development Manual chapter 5.1. For regulations regarding construction and earth disturbance in Ohio please see the OEPA NPDES Construction General Permit.