Initial bioretention studies on water quality and hydrology performance by the NC State University Stormwater Team were conducted in the Piedmont region of North Carolina. Since then, the field sites have been expanded to the Upper Coastal Plain and Coastal Plain.

The research has shown that bioretention is great at removing metals, oils/grease, and total suspended solids. They are good at removing phosphorus and nitrogen species. The exception to this is conventionally drained bioretention cells are poor at removing nitrate+nitrite because there is no mechanism to create denitrifying conditions. It has also been shown that the media should have low phosphorus and organics to prevent leaching. With respect to hydrology, bioretention is good at reducing runoff volumes. It has been shown that deeper systems perform better than shallower systems.

Click on the buttons below to learn more about each study site. These study sites have varying media depths, media composition, drainage configurations, in-situ soils, and vegetative covers.