TBM “Chloe” Breaks Through for Pawtucket CSO Tunnel

Tunnel Boring Machine (TBM) “Chloe the Clean Water Cruncher” has completed excavation of the 2.2 mile long TBM tunnel as part of Phase IIIA of the Narragansett Bay Commission’s (NBC) Combined Sewer Overflow (CSO) Abatement Program, or Restored WatersRI. The TBM was launched on June 22, 2022, breaking through into the receiving shaft on February 15th, 2024. The 30 ft diameter tunnel will provide an additional storage volume of 58.5 million gallons for the collection and diversion of storm-related sewage overflows to NBC’s Bucklin point wastewater treatment facility for treatment prior to release into open waterways. The expanded CSO system will dramatically improve the water quality of Narragansett Bay and Providence’s urban rivers.

Gall Zeidler Consultants (GZ), was responsible for the temporary and permanent works design of all SEM tunnels for the project, including temporary and permanent adit connections to the TBM segmental lining, as well as permanent works design for the large diameter shafts. GZ also provided Independent Design Verification (IDV) services for the TBM segmental lining.

Video of the breakthrough by TBM Chloe can be viewed here.

If you are interested in GZ’s involvement with the project, visit our project page.

TBM Chloe breaksthrough into receiving shaft February 15th, 2024.

Finished Pawtucket CSO Tunnel with segmental lining.

Secant Pile TBM Chloe receiving shaft.