New York University
OP-23: Rainwater Management

NYU follows NYC Department of Environmental Protection's (DEP) Guidelines for the Design and Construction of Stormwater Management Systems. The NYC DEP limits the stormwater release rate for new construction and redevelopment sites. This release rate limit is intended to alleviate pressure on NYC's strained combined sewer system and assist in reducing the frequency and intensity of combined sewer overflow events, sewer backups, and flooding. Although the DEP guidelines do not mandate the use of green infrastructure and LID practices, they are considered methods to reaching the needed release rate. NYU has also emphasized stormwater management, LID, and green infrastructure as a design consideration for new construction and building renovation, as part of the University’s commitment to a standard of LEED Silver for new construction and major renovation projects. NYU's comprehensive building technology review under LEED ensures that best practices in low impact development and stormwater management are considered in new construction and renovation projects. As a part of our sustainable landscaping and green infrastructure initiatives, NYU has seven green roofs that are populated with native perennials that collectively span roughly five acres. These areas are located in some of the densest parts of NYC and do much to mitigate stormwater run-off and influx to the combined sewer system.

DEP’s stormwater performance standard is intended to reduce adverse impacts on the city’s combined sewer system from runoff during rainstorms that are more severe than sewers and related facilities are designed to handle. When excessive stormwater enters the combined sewer system as runoff from impervious surfaces, it can cause combined sewer overflows (CSOs), flooding, and sewer backups. By slowing the flow of stormwater to the sewers, the stormwater performance standard allows the city to manage stormwater runoff from new development and redevelopment more effectively and maximize, to the greatest extent possible, the capacity of the city’s combined sewer systems. DEP allows for different types of stormwater management systems to comply with the stormwater performance standard, including subsurface, rooftop and stormwater recycling systems. These systems store and slowly release stormwater to the sewer system (detention) or dispose of stormwater onsite (retention) through infiltration to soils below, evapotranspiration, and recycling onsite. As a part of meeting the DEP's requirements and pursuing LEED certification, NYU must consider green infrastructure and LID practices for each project - however, they are not mandated.