Over 60 metric tonnes of rock and soil has been removed to protect one of the Sunshine Coast’s most important bulk water pipelines.

A 2.5-kilometre tunnel, located beneath the Blackall Range, houses a pipeline to transport 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, found a number of loose and cracked rocks that threatened to fall and damage the pipeline.

Mr Roche said the tunnel had been excavated through sandstone using drill and blast techniques in the 1980s and had deteriorated over time due to natural weathering.

“The work called for a lot of preparation as it was quite high risk; the tunnel is about 2.6 metres high and 2.5 metres wide and gets pitch black after venturing 50 metres or so inside, with the added risk of rock falling during the work.”

Contractors worked in small teams 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. Late in the works, this meant hauling each cart over 2 kilometres for it to be emptied.

The authorities say the pipeline is not only important for the Sunshine Coast; it is also a critical component in South East Queensland’s Water Grid, as it can transport 180 megalitres of water from the Baroon Pocket Dam to the Landers Shute Water Treatment Plant.