The Hydrologic and Water Quality Performance of the Sligo-Dennis Bioretention Cell

Abstract

Bioretention cells have been found to improve the hydrologic and water quality performance of impervious areas such as parking lots. The current study recorded hydrologic data from a bioretention cell in Silver Spring, MD, over a period of 2 years, collecting water quality data from 14 storm events. Data showed the cell completely captured storm events that produced less than or equal to 1.27 cm of rainfall, after which a linear relationship between cell outflow and cell inflow was observed. The cell was found to reduce the site CN from 96 down to 79 and to have a CN of 96 when assessed as a separate land use. The hydrologic performance was also compared to that of a forested stream near Baltimore, MD. While the cell performed similarly volumetrically for storms producing less than or equal to 2 cm of rainfall, the Sligo-Dennis flow-durations were typically half the length and double the flowrate of those of the forested stream.