Bioretention

The layout of the bioretention area is determined after site constraints such as location of utilities, underlying soils, existing vegetation, and drainage are considered.

[6] Contaminant trace metals such as zinc, lead, and copper are found in stormwater runoff from impervious surfaces (e.g. roadways and sidewalks).

Dissolved forms of heavy metals may bind to sediment particles in the roadway that are then captured by the bioretention system.

[7] In laboratory experiments, bioretention cells removed 94%, 88%, 95%, and >95% of zinc, copper, lead, and cadmium, respectively from water with metal concentrations typical of stormwater runoff.

While this is a great benefit for water quality improvement, bioretention systems have a finite capacity for heavy metal removal.

[9] Therefore, removal and replacement of the bioretention layer will become necessary in areas with heavy metal pollutants in stormwater runoff to extend the life of the treatment system.

A bioretention cell, also called a rain garden , in the United States . It is designed to treat polluted stormwater runoff from an adjacent parking lot. Plants are in winter dormancy.