The NYC Department of Environmental Protection teamed up with the non-profit Osborne Association recently to unveil one of the nation’s first integrated blue and green rooftop systems. Located in the South Bronx, this innovative green infrastructure system will manage over 100,000 gallons of stormwater a year, improve air quality, and even provide the perfect habitat for the Osborne’s future urban beekeeping business.


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Less expensive to install than a traditional green roof, the blue and green roof is a lighter, cost-effective alternative ideal for the city’s older buildings, which might not be able to withstand the weight of a traditional green roof. Designed by Hazen and Sawyer, an environmental engineering firm, the blue-green roof manages stormwater through a two-pronged system. “Blue” detention trays first slow runoff velocity to reduce erosion potential and increase infiltration rates and then “green” trays containing soil and vegetation filter and absorb stormwater.

In a typical NYC storm, the blue and green roof system is estimated to reduce runoff from the building’s roof area by 32 percent. To confirm these estimates and better inform the design of future rooftop stormwater management projects, monitoring equipment on the roof will measure the difference between the precipitation rate and the rate of runoff entering the sewer system.

In addition to tackling the issue of sewer discharges through stormwater management, this innovative roof will improve air quality and reduce pollution inflows to the East River. The green roof will also insulate the building, reducing heating and cooling costs.

“We are excited about this project. With this blue and green roof, everybody wins,” said Osborne Association Executive Director Elizabeth Gaynes. “Our South Bronx community benefits from improved air and water quality; our social enterprise participants gain experience; and it allows us to start a new honey bee business.”

+ Osborne Association

Images via Osborne Association