Three TBMs, including two Robbins machines, will excavate the pipeline, with one contractor-owned machine having completed its 1.4km section in mid-2012. Robbins supplied a 3.25m main beam TBM, and refurbished a 3m double shield TBM in its Solon, Ohio, USA manufacturing facility. Both machines were launched in August 2012 from deep shaft sites.

Within a week of its launch in late August 2012, the main beam machine had advanced about 90m. "We needed the Robbins high performance main beam TBM for the longest bore, which is on the critical path for the project. It¹s built to beat our 230 day schedule, and for even tougher conditions than are foreseen here," said Tim Winn, director of Southland Contracting.

Once complete next year, the pipeline will transfer up to 190 million liters of treated water per day from Lake Travis. The tunnel, for the Austin Water Utility, will connect up with the new Water Treatment Plant 4 currently under construction, which is part of a larger scheme to provide increased water capacity for a projected 60 per cent increase in population over the next two decades.