Green Infrastructure Approaches for CSO Controlin Urban Areas

A nationwide investigation of green infrastructure was conducted for several major metropolitan areas, including Chicago, Milwaukee, New York City, Philadelphia, Pittsburgh, Portland (OR), Seattle and Washington D.C. This report highlights some of the cities' urban green infrastructure projects and the projects' relationship with combined sewer overflow (CSO) control plans and managing agencies. Use of green infrastructure projects outside of the boundaries of formal CSO control plans was wide-spread and diverse throughout the country. The majority of green infrastructure projects used by CSO managing agencies for CSO control have been established separate from the agencies' long term control plan (LTCP) requirements. Portland and Washington D.C. were the only cities that included green infrastructure projects in their LTCPs.Although green infrastructure is not currently used as a major CSO control method in most urban areas, it is being used to compliment engineered solutions and have the potential to gradually improve storage capacity and system performance with increased implementation. As discussed in this report, a number of cities nationwide are now using green infrastructure as progressive elements for urban improvement and realizing the public relations benefit of "being green". A recent USEPA statement of intent promises to support further use of green infrastructure for CSO control in urban areas.