1. Low Impact Design
Bio Retentions

2. What are they?
-Landscaped depressions or shallow basins where stormwater is directed to the basin and then percolates through the system where it is treated by a number of physical, chemical and biological processes.
-The slowed, cleaned water is allowed to infiltrate native soils or directed to nearby stormwater drains or receiving waters.
-Leveled with non invasive vegetation and treated soil as a filter

3. The Layers
Grass buffer strip- reduces runoff velocity and removes suspended solids.
Vegetation –Help remove water through process of evapotranspiration and remove excess nutrients through nutrient cycling.
Shallow ponding area –provides storage of excess stormwater flows and its subsequent evaporation, also aids in the additional settlement of particulate matter.
Mulch –an organic layer that encourages micro biological degradation of petroleum-based pollutants, aids in pollutant filtration and reduces soil erosion.
Engineered soils –to support vegetation growth along with nutrient uptake and provision for water storage. Soils should include some clay to adsorb pollutants such as hydrocarbons, heavy metals and nutrients.
Sand bed –provide drainage and aeration of planting soil as well as an aid in flushing pollutants.
Underdrain system –removal of excess treated water to storm drain system or receiving waters.

5. Examples University of Vermont Parking lot
A typical bioretention basin in Philadelphia
University of Vermont Parking lot

6. Success Story - Storm Management In the Hudson Valley
Beacon Institute
Dutchess County Community College (1+2)
Newburgh Town Hall
Pierson Park
Installed in 2008 and Largely funded by a grant from NYSDEC Hudson River Estuary Program
It protects the water quality of the Hudson River by capturing and filtering stormwater runoff from the building and site.
The location chosen was a naturally occurring basin in the existing landscape, maintaining the project's low-impact footprint. In addition, the plants in and around the basin are native to this area, have excellent filtering capabilities, and attract birds, butterflies and wildlife.

7. Citations
Stormwater Management - Bioretention Basins. (n.d.). Retrieved from
Chapter 4 - Stormwater Management Practice Guidance. (n.d.). Retrieved from