State Water Resources Research Institute Program
Project ID: 2009MA199B
Title: Characterization of Flow and Water Quality of Stormwater Runoff from a Green Roof
Project Type: Research
Start Date: 4/ 1/2008
End Date: 3/30/2009
Congressional District: 3
Focus Categories: Water Quality, Hydrology, Water Quantity
Keywords: green roof, water quality, stormwater runoff, NPDES Permit
Principal Investigator: Mathisen, Paul (Worcester Polytechnic Institute); LePage, Suzanne (Worcester Polytechnic Institute)
Federal Funds: $ 4,900
Non-Federal Matching Funds: $ 9,823
Abstract: The Clean Water Act Stormwater Phase I and Phase II rules have heightened the awareness and sense of urgency in communities that need to mitigate the negative impacts associated with stormwater runoff. Best Management Practices (BMPs) for site design and stormwater control are typically encouraged for use in meeting regulatory requirements, and green roofs are increasingly being used in urban areas. The ability of green roofs to reduce the total and peak volumes of stormwater runoff has been fairly well documented, but there is limited, and sometimes conflicting, data regarding the ability for green roofs to improve water quality.
The objective of this project is to use a monitoring program to assess the effectiveness of a green roof in a new residence hall at Worcester Polytechnic Institute (WPI) in Worcester, Massachusetts. Efforts are currently underway to monitor the rate and quantity of stormwater runoff retained on the green roof in comparison with the "non-green" portion of the roof, while simultaneously recording precipitation data. The proposed research will additionally assess water quality parameters (including, pH, temperature, and nutrients) in an effort to expand our knowledge of the effectiveness of green roofs in improving stormwater quality. Of particular interest is the potential for the vegetation on green roofs to improve the quality of rainfall through plant uptake of nitrogen, especially in light of Eastern Massachusetts' air quality nonattainment status, in large part due to emissions of volatile nitrogen oxides (NOx). It is anticipated that the results of this monitoring effort, combined with previous research results from literature, will supplement the information available to communities in the Commonwealth regarding the effectiveness of green roofs for use as a Low-Impact Development BMP for stormwater management.
Progress/Completion Report, 2009, PDF