The Santos Ltd.-operated Gladstone LNG project has passed another milestone with the final section of the coal seam gas supply transmission pipeline now laid through a tunnel underneath Gladstone harbor to the LNG plant site on Curtis Island.
One hundred and twenty pipe segments, each 36 m long, were welded and gradually pushed through the 4.3-km tunnel using a large hydraulic jack.
The tunnel was first filled with seawater to give buoyance to the 42-in. line as it was pushed through.
The operation brings the 420-km supply pipeline from fields in the Surat and Bowen basins of central-eastern Queensland to its final stages of construction.
The marine crossing pipe will now be connected to the buried mainland and island sections of the line.
Saipem Australia was the pipeline contractor while Theiss was responsible for the tunnel construction.
Pipeline precommissioning works are under way with 50% of the required hydrotesting completed.