Dorsey breaks through on second US tunnelling project


Dorsey’s breakthrough

A major breakthrough on the Norris Cut Project in Florida has marked a milestone in Bessac’s second US project.

The French tunnelling contractor, which is celebrating 40 years of operation, first moved into the US with the Ellis Avenue Tunnel in Los Angeles.

The Norris Cut Project was commissioned by the Miami-Dade Water and Sewer Department and valued at approximately US$72.1 million.
The project involved the construction of a 5,200 foot (about 1585 m) tunnel to replace the existing force main running between the Virginia Key Central District Wastewater Treatment Plan and Fisher Island.

Tunnel construction took ten months to complete and used a 10 foot (3 m) tunnel boring machine (TBM), Dorsey.

The general construction contract was awarded to Nicholoson Construction who subsequently teamed up with sister company Bessac.

Bessac, a subsidiary of Soletanche Bachy, is a worldwide major tunneling and microtunneling contractor, with 40 years of experience. Bessac masters all mechanized excavation techniques, such as microtunneling, EPB TBM, slurry TBM, air pressurized TBMs.

Bessac took up the position of tunnel construction management.

Bessac President Bernard Theron said “The Norris Cut Project has benchmarked the underground activity in Florida by opening new solutions for deep sewers in porous Fort Thompson geological formations. Thanks to the design-build approach, we managed to implement innovative solution such a combining pipe jacking and universal segments, treating ground from the TBM to allow hyberbaric interventions.”

The tunnel was designed by ARUP and AECOM participated as the Miami-Dade Water and Sewer Department’s primary consultant.

All work on the Norris Cut Project is expected to be completed in mid-2016.



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