The existing outfall pipe at the Bergen Point Waste Water Treatment Plant (WWTP) in Babylon, Suffolk County, NY, has to be replaced. A 4.33 km (14,200-foot) tunnel, with a 3.05 m (120-inch) inner diameter will be constructed by a TBM to replace the existing Prestressed Concrete Cylinder Pipe (PCCP). This outfall pipe carries millions of gallons of treated wastewater, connecting the Bergen Point Wastewater Treatment Plant (WWTP) to the Barrier Island under the Great South Bay. The new tunnel will address the concerns of a potential failure of the current pipe and has a longer lifespan.

In May 2018 the joint venture of OHL USA Inc (40%), Posillico Civil Inc (40%) and SELI Overseas USA Inc (20%) were awarded the EUR165.45 million (USD187 million) contract by Suffolk County Department of Public Works to build the new tunnel.

The joint venture has selected a slurry TBM as the most effective and efficient means of tunnel excavation and elected to use 122 cm (48-inch) wide precast segment liners. Construction started on February 8th, 2018 and will be completed by the summer of 2021. The shaft construction will be divided into major work phases including site preparation, excavation of the launch shaft and installation of the new TBM. The TBM will drive through a mixture of soft soil materials under the Great South Bay.

A mixshield TBM (diameter 3.8m) is now ready at the Herrenknecht factory, and will shipped to New York. The TBM is equipped with 14” cutters/rippers, it will have a 0-6.5 RPM cutterhead rotation speed, 315 kW cutterhead drive power and cutterhead maximum torque:  1.600 kNm

Once the TBM is installed, tunnel excavation will continue in four foot “pushes,” followed by the installation of the permanent tunnel lining.

Additionally, the team will also complete ancillary work within the tunnel including the installation of new piping and valving, associated plumbing, HVAC, and electrical work. For further information please visit https://www.suffolkcountyny.gov/Departments/Public-Works,

http://www.ohlusa.com, https://www.posillicoinc.com/ and http://www.selioverseas.com/. 10/19.