The Dampier Bunbury Pipeline consortium, which comprises DUET, Alcoa and Alinta, said the draft decision released by the ERA was an important first step in moving towards final approval of the expansion.

“DBP intends to work closely with the ERA to address a number of matters arising out of the draft report before the final decision,” DBP executive chairman Stuart Hohnen said.

The proposed stage 5 expansion – to be completed in phases by 2009 – would add about 1150km of looping and additional compressor units to boost capacity a further 375 terajoules per day.

At an estimated cost of about $1.5 billion, the proposed Stage 5 expansion would be one of WA’s largest-ever construction projects.

Currently underway is the $430 million Stage 4 expansion, which will add more than 100TJ/d, and is expected for completion by January next year.

The ERA has now called for public submissions on the draft decision.