About Vegetated Swales
General Information Performance Data Water Quality Treatment Process Design


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Water Quality Treatment Process

1. Stormwater runoff flows into and along the swale’s channel, where water quality performance is a function of channel dimensions, density of vegetation, and its ability to dampen the influent flow rate.

2. Runoff undergoes physical filtration through the standing vegetation. In systems with more robust vegetation, additional treatment via plant uptake and sorption to organic sediments may occur. Water quality performance typically increases with vegetation density, and declines during high flows when vegetation is submerged, frozen, and/or bent.

3. Sedimentation occurs between the large stones lining the flow pathway. If the swale is constructed above highly conductive soils and flow is of low velocity, infiltration also can be expected.

4. Increased detention time from check dams within the channel coupled with low velocity flows will enhance filtration, sedimentation, and infiltration.

5. Water leaving the system is directed to a receiving water.