About Bioretention System (Bio II)
General Information Performance Data Water Quality Treatment Process Design


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Water Quality Treatment Process

1. Runoff flows into a sedimentation forebay or other pretreatment chamber. From there, it is slowly released into the filter basin through a perforated standpipe. When forebay capacity is reached, the overflow spills across a weir into the bioretention basin.

2. Biological treatment occurs through the uptake of pollutants by vegetation and soil microorganisms. Physical and chemical treatment (occurring within the soil media) includes sedimentation, filtration, and sorption with organic matter and mineral complexes.

3. Nutrients like nitrogen are taken up by the roots of the vegetation and metabolized by the system’s plants, shrubs, and trees.

4. The treated runoff can be allowed to infiltrate the native soils, or collected in a perforated subdrain and returned to a storm drain system or discharged to the surface.