New York City proposal would require rainwater detention tanks for new development

A proposal under consideration in New York City would require developers to install a rainwater detention tank on many new projects within the city limits.

The rule would apply to projects on lots sized 20,000 square feet or more in designated drainage areas. It would require developers to install a detention tank that could capture more than the stormwater volume of a 10-year rainfall event.

There would be a one-inch maximum diameter for the detention tank’s orifice, where water would exit, in order to create greater retention and a slower release of stormwater. This strategy was created after the city shifted away from the idea of creating separate sewer lines.

City officials rejected separating stormwater and wastewater lines because that massive public works project would have been too costly and would have taken too long to implement.