Providence, RI – Construction has kicked off for the final phase of the Narragansett Bay Commission’s (NBC) Combined Sewer Overflow (CSO) Program, which is expected to reduce overflow volumes by 98% and treat stormwater before it flows into the Narragansett Bay.
The program will also reduce the closure frequency of shellfish beds in the bay, which has had a major economic impact on the community. Stantec, supported by teaming partner Pare Corporation, is serving as the lead designer and program manager for Phase 3 of the project.
Phase 3 involves the construction of the Pawtucket Tunnel, a 2.2-mile long, 30-foot diameter tunnel running underneath the communities of Pawtucket and Central Falls. Located at depth ranges of 115-155 feet below grade, the tunnel is designed to store 58.5 million gallons of combined sewer overflows.
The CSO Program’s first phase kicked off in 2001 with the construction of a three-mile long, 26-foot wide deep-rock tunnel under Providence to store stormwater runoff. Phase 2, completed in 2015, added CSO interceptors to the Providence Tunnel, several sewer separation projects, and a wetlands storage facility.
The project’s design-builder is CB3A, a joint venture comprised of CBNA, a U.S.-based subsidiary of French construction engineering firm Bouygues Travaux Publics, and local civil works contractor Barletta Heavy Division, in association with designer AECOM. Notice to proceed has been granted under a design-build contract worth $450 million.
Melissa Carter, vice president of Stantec, said, “We are delighted to see ground break on the final phase of this momentous project, which will support the local economy and protect Rhode Island’s beaches and water quality in Narragansett Bay for generations to come.”