Zone of instability in Savannah raise

PANORAMIC Resources has come up with a plan to resolve the ground instability issues at Savannah North after a down-hole laser scan and video inspection pinpointed a zone of instability within the ventilation raise.
Zone of instability in Savannah raise Zone of instability in Savannah raise Zone of instability in Savannah raise Zone of instability in Savannah raise Zone of instability in Savannah raise

Ventilation shaft foundations

Savannah North is part of the Savannah underground nickel sulphide mine in Western Australia's East Kimberley.

Panoramic accessed first development ore from Savannah North in November, with stoping operations scheduled to begin on the first stope in March.

As part of the development Panoramic initiated additional ventilation works, with the ventilation capacity raise bore advancing 210m over the December quarter to be about 60% (535m) complete.

The work was shelved however in December when ground instability inside the raise made reaming too dangerous.

A remote laser-scanner was sent down the hole to survey the bore, which found areas of instability within the raise.

A 490m long access drift will be built to intersect the half-finished ventilation raise about 690m below the surface collar and 70m above the zone of instability, so the reaming head can be reconnected, and excavation can resume of the last 340m.

Panoramic estimate this extra work will cost $4 million and be finished by the September quarter.

According to the company, this lateral access will allow for the raise's lower section to be monitored and give it easy access to implement further stabilisation measures in the future if needed.

The drift development work will be done by Savannah's underground mining contractor, Barminco, with RUC to finish off the raise bore drilling then commission the intake shaft.