New Jersey Stormwater Best Management Practices Manual Chapter 9 Bioretention Systems
A bioretention system consists of a soil bed planted with native vegetation located above an underdrained sand layer. It can be configured as either a bioretention basin or a bioretention swale. Stormwater runoff entering the bioretention system is filtered first through the vegetation and then the sand/soil mixture before being conveyed downstream by the underdrain system. Runoff storage depths above the planting bed surface are typically shallow. The adopted total suspended solids removal rate for bioretention systems is 90 percent.