By Lynda Myer
Manufactured by Herrenknecht for Narragansett Bay Commission’s (USA) Pawtucket Tunnel Project, the 10.3m Multi-Mode TBM on 14 January 2022 passed its Factory Acceptance Testing. The customers of this TBM were the CB3A Joint Venture which includes CBNA (Civil & Building North America Inc.), Barletta Heavy Division Inc., and AECOM for construction and it is expected to reach Rhode Island in the Spring of 2022, while NBC’s CSO Phase III comprises construction of a 3.5 km long and 9.14 m (30 ft) in diameter deep rock tunnel that is due to be driven by this machine along the Blackstone River in Pawtucket.
In order to stock the volume of the combined sewer overflows (CSOs) in Providence, Pawtucket, and Central Falls, the Pawtucket Tunnel is designed. While the stored volume will be pumped to the BPWWTF by the Tunnel Pump Station, the Tunnel Pump Station is being prepared for a firm capacity of 27.3 MGD. Considering a formal rating of 9.1 MGD each of four original dewatering pumps is going to be designed for this project and the combined capacity of all three main pumps will be 27.3 MGD. The fourth pump will serve as a standby. To accommodate a wide range of flow conditions, each of the four main pumps will be provided with a variable frequency drive (VFD).
Until bettering the performance of the secondary treatment to accommodate future tunnel pump-out operations after wet weather events the upgrades to the BPWWTF are necessary. The BPWWTF, placed in East Providence (Ri), ministers the 75-square mile Bucklin Point Service Area (BPSA), treating flow from all or parts of East Providence, Pawtucket, Central Falls, Smithfield, Cumberland, and Lincoln.
Commencing its operation in 2016, phase III of the program (Phase III CSO Program) is concentrated primarily on the Bucklin Point Service Area (BPSA) in the communities of Pawtucket and Central Falls. The estimated date for its completion is 2041.
The sub-sections of Phase III CSO Program are as follows:
- Phase IIIA: Pawtucket Tunnel
- Phase IIIB: Upper BVI Relief Structure and OF-206 Sewer Separation
- Phase IIIC: Stub Tunnel to Control OF-220
- Phase IIID: West River Interceptor and OF-035 Sewer Separation
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