The blocked paste reticulation circuit led to a delay in the paste filling of open stopes and has thrown out the mining schedule St Barbara has to use due to the ventilation constraints and the nature of the orebody at Gwalia.
It has delayed the mining of one stope on the 1660 level, which was originally due for production in June through to July.
The stope in question has 56,000t of ore grading an estimated 8 grams per tonne gold, representing 14,900 contained ounces of gold.
Paste-fill operation has resumed, and while the cost of remediation is not material, the damage to the schedule has been done.
Normally such an event can be managed over the course of a financial year.
However, this incident occurred almost at the end of the 2018-19 financial year, leaving St Barbara no room to move.
Given the sequential mining schedule, ventilation considerations in completing concurrent work activities and the resources needed for the remaining Gwalia Extension Project Paste Aggregate Fill construction, it is not possible to replace the delay in the project of this stope in 2018-19.
The revenue and costs of mining this stope are being delayed one month from June to July.
While Gwalia has been blighted by the delay, things are going well at St Barbara's Simberi gold mine in Papua New Guinea. It is expected the miner will produce about 135,000oz of gold in 2018-19 - the upper end of its 130,000-135,000oz guidance.
Consolidated gold production for the 2019 financial year has been revised to 355,000oz. St Barbara had been hoping for 365,000-375,000oz.