Performance Evaluation of Blue Roofs to Mitigate CSO Impacts

As part of the green/grey infrastructure evaluation and implementation efforts being pursued by the New York City Department of Environmental Protection (NYCDEP), blue roofs (rooftop detention systems) are being pilot tested to reduce peak flows reaching the combined sewers and mitigate combined sewer overflows during rainy periods. Performance evaluation of these systems to reduce peak flows is necessary to quantify their effectiveness and incorporate them in the assessment of benefits at neighborhood and watershed scales. This paper reviews the roof-scale calibration of a pilot blue roof and provides directions for future work to evaluate the performance of multiple blue roofs at varying spatial scales in an urban drainage model.