CSO Project Construction

Combined Sewer Overflow (CSO) Construction

Construction related to Phase II of the Narragansett Bay Commission's Combined Sewer Overflow has been completed. For the history of the project, click here. For information on the Phase III stakeholders process, click here.

NBC's CSO Program is a federally-mandated water quality improvement project mandated by the 1972 Federal Clean Water Act, and will enable Rhode Island to meet the Department of Environmental Management policy to "elminate overflows from a three-month storm" (1.64 inches of rain in six hours). Phase I of the project included a deep rock tunnel that captures sewage overflows and transports the flow for treatment to the NBC's Field's Point Wastewater Treatment Facility. Phase II included two near surface interceptors along the Seekonk and Woonasquatucket Rivers to bring additional flow to the Phase I tunnel, a new storm drainage system in the Summit neighborhood, and a constructed wetlands in Central Falls. Phase III includes another deep rock tunnel and several Green Stormwater Infrastructure (GSI) projects in Pawtucket and Central Falls.