A joint venture of OHL USA, Posillico Civil and SELI Overseas USA have been awarded a $187M contract by Suffolk County Department of Public Works to replace an existing outfall pipe at the Bergen Point Waste Water Treatment Plant (WWTP) in Babylon, NY.
This is the largest construction project in Suffolk County in several decades. Construction started on February 8 and will be completed by summer 2021. The project includes the construction of a 14,200ft (4.32km), 120-in (3m) i.d. tunnel through a mixture of soft soils under the Great South Bay with the use of a TBM.
The tunnel will be constructed to replace the existing Prestressed Concrete Cylinder Pipe (PCCP) outfall pipe, which 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 potential failure of the current pipe and has a longer lifespan.
The tunnel will be excavated and concurrently lined using precast concrete segment rings. The JV has selected a slurry TBM as the most effective and efficient means of tunnel excavation and elected to use 48-in (1.2m) wide precast segment liners. Shaft construction will be divided into major work phases including site preparation, excavation of the launch shaft and installation of the new slurry TBM. 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.