Santos has commenced preparations for tunneling under Gladstone Harbour with the arrival of a 277 tonne tunneling machine.
The construction of the tunnel beneath Gladstone Harbour is for the Santos GLNG gas pipeline to Curtis Island.
Project Pipeline manager Greg Jones told Gladstone Observer that the machine was a smaller version of the one that had been used on the Brisbane Airport Link.
"Good progress has been achieved on building the launch shaft at the Narrows Crossing in Gladstone, where the 70-metre-long machine will start work," Jones said.
"We have completed sheet piling in the launch shaft and excavation of the shaft is well underway.
"The first of four phases of concrete pouring to create a concrete base slab in the shaft has also been completed."
The tunnel boring machine, known as a TBM, has 16 main pieces of kit including a cutterhead, front steering shield, machine shield, tailskin and 11 back-up gantries, it was transported up from Brisbane and is currently being assembled onsite.
Before the machine can be pre-commissioned and operated each of the 16 kits needs to be installed, a process which takes 10 team members about four weeks.
Jones said the 12 month tunnelling project would begin in coming months.
"TBM tunnelling is a cyclical process consisting of two distinct activities – excavation and construction of the walls of the tunnel," he said.
"Rock and soil is excavated by rotating the cutterhead, while the hydraulic ram works to push previously installed wall segments into place to stabilise the tunnel.
"Once completed, the tunnel will be flooded with water, and the gas transmission pipeline strung together and pushed and pulled through the length of the tunnel."
Already to the south pipeline construction has commenced.
"In Arcadia Valley, we have completed all welding of the pipe and are now concentrating on burial and backfilling activities," he said.
"In Banana Shire and Lonesome Holdings, clearing and grading work is underway while in Fairview, clearing and grading is complete and stringing and welding of pipe continues."
Late last year Australian Mining reported the $16 billion GLNG project was on track, despite speculation over cost blowouts.
At the time Santos said the GNLG projects on Curtis Island are on safe ground.
Chief executive of GLNG Mark Macfarlane said solid progress had been made in key areas, and the company would concentrate on building on this progress rather than expanding.