A detention pond, or “detention basin,” is a large, constructed or excavated depression in a community or an urban landscape that receives and stores the stormwater runoff from large drainage areas. Detention basins usually hold a permanent pond of water, and are sometimes called “wet basins.”
Similarly, a retention basin is a depression that also collects and slowly releases stormwater from large drainage areas. However, a retention basin is different because it is not permanently covered with standing water. The attribute gives them the name “dry basins.” A rain garden is a type of small retention basin.
Why use Detention Ponds?
Detention ponds are an excellent way to naturalize the stormwater patterns of a larger urban area. Rain gardens, infiltration trenches and bioswales collect stormwater runoff from smaller areas, and are most effective when used to treat the water from one urban land parcel. However, detention ponds are so large, and hold so much water that they are more effective when implemented at the community level.
Detention ponds primarily manage stormwater quantity, but also somewhat contribute to treating the water quality. When it rains over a detention pond’s drainage area, the runoff water either travels to the pond across the land surface or is routed there by gutters or underground pipes. In some cases, the water is passed through a pretreatment wetland or sedimentation tank. These additional treatment cells are included to remove extra sediment and dissolved pollutants from the water. Once the water leaves these pretreatment cells, it then enters into the permanent pond and slightly raises the water level. Because they are a designated area for water storage, detention ponds prevent water from flooding in the community’s developed areas.
The runoff is stored in the pond, and slowly released in the storm water sewer system. The storage-release process reduces the peak runoff volumes and runoff rates. The implications of these reductions in “quanity” are that the stormwater sewer system and treatment facility can be designed to handle smaller volumes. Also, when the water pools in the basin, its velocity is significantly reduced. This allows suspended sediments to sink to the bottom of the pond, and the organic pollutants to be digested by the organisms present in the pond. This improves the water “quality.”
Detention & Amenity Pond Services We Provide:
- Vegetation Management
- Reconnaissance and Site Evaluation
- Erosion Control
- Outfall Interceptor Repair
- Outfall Pipe Repair
- Slope Rehabilitation
- Slope Paving Repair
- Flow Line Dip Out