|Stormwater treatment wetlands are one of the most effective best management practices for removal of pollutants from stormwater. These wetlands have been found to be highly effective at removing total suspended solids (TSS), biochemical oxygen demand (BOD), metals, and plant nutrients such as phosphorus and nitrogen.
Stormwater treatment wetlands typically consist of several features designed to retain and filter water. First, the water flows into a forebay that removes the coarse sediments. This forebay is checked and cleaned as needed. It prevents sediment from clogging the main filtration basin, particularly during construction. The water then flows into a broad primary treatment basin through a long circuitous channel in order to maximize exposure to the wetland filtration processes. Finally, the water level and rate of discharge are controlled by an outfall structure. An assortment of shallow and deepwater emergent vegetation is then utilized throughout the main treatment basin to create the effective filtration environment.
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Some design considerations include:
- A Forebay to remove excess sediment
- Maximize the water depths under 18"
- Develop a long circuitous path for the water to travel in order to maximize exposure to the filtration process