NYC Announces Major Expansion of Nationally Recognized Green Infrastructure Program

Data Collected from Pilot Program Demonstrates that Green Infrastructure Installations Performed Even Better Than Anticipated

A comprehensive monitoring program serves as the foundation of the City’s adaptive management approach, providing key insights into system performance, life cycle costs and benefits, maintenance requirements, and external factors like community perception, which are guiding and enhancing ongoing implementation efforts.

There are currently 255 bioswales in the ground throughout the City and there are plans to add thousands more over the next several years.

Data downloaded from temperature sensors, water level loggers, and time lapse cameras provide insight into bioswale performance.

(NEW YORK, NY – November 14) -NYC Department of Environmental Protection (DEP) Commissioner Emily Lloyd today joined partner agencies, elected officials, environmental advocates and community groups to announce a major expansion of New York City’s nationally recognized Green Infrastructure Program.

Over the coming months the City will accelerate the ongoing construction to build approximately 2,000 specially designed curbside gardens in Brooklyn, the Bronx and Queens. When construction is completed, the 2,000 curbside gardens, also called bioswales, will have the capacity to collect and absorb more than 4 million gallons of stormwater when it rains. It is estimated that the bioswales will capture more than 200 million gallons of stormwater each year, thereby improving the health of the Bronx River, Flushing Bay, Gowanus Canal, Jamaica Bay and Newtown Creek. There are currently 255 bioswales in the ground and there are plans to add thousands more over the next several years.

Bioswales are built in city sidewalks and do not result in the loss of any parking spaces. They resemble standard street tree pits, except that they vary in size, have curb cuts that allow stormwater to enter and overflow, and have been designed in a way that will allow them to manage between 1,300 and 3,000 gallons each during a storm. During construction, the bioswales are excavated to a depth of five feet and are then backfilled with layers of stone and engineered soil. These layers contain void spaces that store the stormwater and promote infiltration. The addition of hardy plants further encourages infiltration through root growth and increases the capacity of the bioswale through evapotranspiration. The bioswales are designed so that all the stormwater is absorbed in less than 48 hours.

By softening the impervious urban landscape and naturally absorbing rainwater that would otherwise drain into the combined sewer system, the multi-agency effort will help to reduce combined sewer overflows into local waterways. Analysis shows that this adaptive approach to improving the health of our waterways, in addition to the ancillary sustainability benefits, can be achieved at a lower cost than a traditional strategy that does not include green infrastructure. In addition, some of these neighborhoods currently have less than average street tree counts and higher than average rates of asthma among young people. The increased tree canopy and vegetation created through the addition of the bioswales will help to improve air quality, provide shade during hot summer months, and beautify the neighborhoods.

For more information, visit the NYCDEP website.

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