More than 60 t of rock and soil has been chipped away and removed from the underground tunnel to protect a bulk water pipeline in the Sunshine Coast, Queensland.
The 2.5 km tunnel is located beneath the Blackall Range and houses a pipeline that transports water from Baroon Pocket Dam to the Landers Shute Water Treatment Plant in Palmwoods.
Seqwater Asset Engineer Daniel Roche said inspections of the tunnel, carried out by geotechnical and civil engineers, is what found several loose and cracked rocks that threatened to fall and damage the pipeline.
Mr Roche said advances in technology helped make it easier to detect potential issues in the tunnel and solve these issues before devastating impacts had been made.
“For example, we can now use laser scanning to create a 3D model of the tunnel which helps identify and record any cracks appearing in the tunnel that might not have been there before or movement within the rock,” he said.
“In order to maintain this critical link, regular inspections and repairs will be carried out in the tunnel, to ensure it remains a safe environment to access and work in, with minimal risk of damage to the pipeline.”
In the 1980s, the tunnel had been excavated through sandstone using drill and blast techniques and had deteriorated over time due to natural weathering.
Seqwater Dam, Recreation and Catchment Operations Coordinator Phil Benson said small teams worked together to manually remove the rock using pry bars, then loaded the rock into a small cart fixed to a rail to transport it out of the tunnel.
“As the project neared completion, the team was having to walk more than two kilometres into the tunnel to excavate the rock, load the cart and head back,” said Mr Benson.
“Providing power for the work to take place, maintaining communication with the team in the tunnel and working during wet weather – all provided additional challenges we had to overcome.”
The pipeline, which is now secured, is not only important for the Sunshine Coast but stands as a critical component in southeast Queensland’s water grid with its ability to transport 180 ML of water.
For more information visit the Seqwater website.
If you have news you would like featured in Trenchless Australasia contact Assistant Editor Sophie Venz at email@example.com