Green Infrastructure to Reduce Stormwater Runoff in New York City: Post-Construction Monitoring over Multiple Years and Lessons Learned

摘要

Water quality in New York Harbor is currently impacted by combined sewage and stormwater discharges during large or intense rainfall events. In accordance with the 2012 Modified Combined Sewer Overflows (CSO) Consent Order, the New York City Department of Environmental Protection (DEP) will implement green infrastructure (GI) practices incrementally over the next two decades to manage one inch of runoff from 10% of its impervious surfaces in combined sewer areas city wide. In 2009, the City began designing, constructing and monitoring the performance of multiple pilot projects including enhanced tree pits, vegetated infiltration swales, rain gardens, blue roofs, pervious pavement, and underground infiltration systems to inform the citywide build-out of GI. These GI systems have been constructed in a variety of locations including in the right-of-way, highway medians, park-and-ride lots, public parks, and public housing facilities. Construction was completed in 2011 for most systems, with post-construction monitoring (PCM) of each completed system continuing over two years. Monitoring has been conducted to quantify inflow and outflow rates, ponding levels, drawdown rates, and water quality, and to examine maintenance needs and overall system functionality.