S.A. Healy-Salini Impregilo is the lowest bidder with USD 187,963,000. The city will assess the bids and said it will announce the award in three to four weeks.
The main tunnel will be approximately 5-miles (8km) long and will be located at depths of 160 to 180ft (48.7 to 54.8m), in bedrock. This will be a TBM drive with a diameter of 16-18ft (4.8 to 5.4m).
As part of the tunnel works, a mile of consolidated sewers will be constructed by open cut and trenchless methods near surface sewers that will collect combined sewage from the existing sewer system and connect to drop shafts to the main tunnel. There will be two miles of relief sewer at the south end of the tunnel that will be constructed by open cut.
