In the company’s latest project update, underground geotechnical engineer Kane Allen said over the past two months TBM Florence, which is building the headrace tunnel, has made an average advance of 40mm per minute.
“The last couple of months she really has been hitting goals,” he said.
The TBM, which is currently mining in open mode, is working through a “pretty friendly formation”. The Tangtangara Formation is sediment, comprising mainly sandstone and siltstone, deposited in a marine environment 440 million years.
While TBM Florence continues to build the headrace tunnel, work at the Tangtangara site continues on several fronts, including the intake structure and the gate shaft. This has required development of a unique concrete mix that can been poured in freezing conditions.
On average, 1,000m3 of concrete a week is being poured to build the intake structure.
TBM Florence was launched from the Tangtangara site in March 2022. In 2023, she was halted for several months after a surface depression developed at the end of 2022. Work was stalled again in May 2024 when the machine hit hard and abrasive rock.
