David Lees and Associates were appointed by KBR to provide an initial design and costings for a tunnel for the LNG pipeline crossing to Curtis Island for Origin Energy.

The 2.3 kilometre Narrows Crossing included excavation through a major fault with difficult access in mangrove mud flats.

The proposed design by TBM for a 3.5m diameter tunnel was unique for a gas pipeline. Construction access to the TBM entry pit on the mud flats also required innovative ground treatment techniques to support the heavy construction equipment.