An 830 metre tunnel under the Toolangi State Forest, which forms part of the Sugarloaf Pipeline, has been completed using ‘Ollie’, an $A8 million, 100 tonne remote-controlled tunnel boring machine (TBM). The tunnel was started on 1 April and took a crew of ten workers ten weeks to complete.
Ollie was manufactured especially for the rock encountered in the Toolangi State Forest. According to Sugarloaf Pipeline Alliance project manager Rob Cranston, most of the rock tunnelled through was 8–10 times stronger than structural concrete.
Ollie is guided remotely by an above-ground operator. As it cuts through the rock, the TBM uses precast pipe sections to drive the machine and provide immediate ground support. The sections are pushed forward using a large hydraulic jacking frame.
The TBM mixes the excavated material with slurry for transport back to the surface, where it is segregated by a large slurry treatment plant onsite. Some of the rock has been used elsewhere on the Sugarloaf Pipeline. The majority is disposed of at the old Castella Quarry.
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