The JV of Jay Dee Contractors/Frank Coluccio Construction/Taisei Corporation (JCT J.V.) has announced that “Elizabeth” its 4.7m diameter Lovat EPBM is just short of the Ballinger Way retrieval shaft ready for breakthrough any time now on the 6.4km long West Tunnel drive, on the US$1.8bn, 20km long Brightwater tunnel project in King County, Washington, US.
Having launched in September 2008, the J.V. has successfully completed the 6.4km tunnel, which was the longest single heading of the project, with no intermediate access from the surface. The tunnel was driven up gradient in an easterly direction from Point Well Portal Structure to Ballinger Way Retrieval Shaft. The TBM traversed glacially deposited outwash and tills, under hydrostatic head conditions exceeding 5 bar pressure.
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The TBM performed exceptionally well with its best day, being April 7, 2009 where it mined 26 rings (43m) in one shift; best month was April 2009 with 392 rings (645m) of production.
With the success of the TBM drive on the BT4 tunnel contract, the JV of Jay Dee Contractors/ Frank Coluccio Construction has been awarded the construction of 3.3km (Reaches 3C & 3D) into the troubled Brightwater Central BT3 tunnel section.
The TBM will require some modifications, which are currently underway, to tackle the anticipated 7.3 bar of combined earth and water pressure in the BT3 Central Contract.