The TBM that will mine a third 4.83km raw water intake in Las Vegas was unveiled last week. The 6.36m diameter Herrenknecht machine, that will bore at the Lake Mead reservoir, was presented by the Southern Nevada Water Authority.

The USD 447M design/build contract was awarded to Vegas Tunnel Constructors, a joint venture consisting of Lombard, S. A Healy and Impreglio.

The 1,500t TBM was shipped from Schwanau in Germany to the Port of Long Beach, California, and then transported to the Nevada jobsite by road.

Some 2,500 precast concrete rings each formed of six segments will be installed. The 9.5m diameter, 190m deep access shaft is equipped with a gantry system with dual 200t winches.

The TBM will begin boring next month and is expected to meet the project completion date of July 2012.