Over the next several years, NYC will spend up to $187 million toward green infrastructure implementation in combined sewer areas. Since 2009, DEP has been selecting appropriate sites, and designing and constructing green infrastructure pilots in various locations throughout the Bronx, Brooklyn and Queens. These pilots informed the development of NYC’s Green Infrastructure Plan and continue to shape future planning and design efforts. DEP’s pilot projects include 25 source controls such as blue roofs, green roofs, bioswales, bioretention, porous pavement, subsurface detention infrastructure, among other types of structural facilities designed to manage stormwater runoff on publicly owned sites.

This report summarizes initial monitoring results and preliminary observations made in 2011 for a number of individual source controls. In general, the purpose of the monitoring effort is to: a) evaluate the effectiveness of various green infrastructure practices at managing the 1-inch rainfall event, and b) provide data that will allow DEP to extrapolate the runoff reduction benefits on a large scale. Specifically, the stormwater pilot monitoring aims to evaluate the effectiveness of each of these source controls at reducing the volume and/or rate of stormwater runoff from the drainage area through measuring quantitative aspects like source control inflow and outflow rates, as well as maintenance requirements and co-benefits. Additional background information on the specific design and monitoring plans for these source controls can be found in NYC’s Green Infrastructure Plan and 2011 Update.

• 2011 Preliminary Pilot Monitoring Results