Production Resumes at Cadia

Newcrest Mining recommenced processing at its Cadia operations at the beginning of April with the associated tailings being deposited into the southern tailings facility. Processing is currently at a run rate of approximately 8 metric tons per year (mt/y) due to limitations in infrastructure to the southern tailings facility. The southern tailings facility has been inspected, independently reviewed and assessed to be safe for tailings deposition. Increased monitoring has been implemented, with new real-time radar monitoring scanning the length of the wall for ground movement every 30 minutes, coupled with daily physical geotechnical inspections and regular drone surveys to verify the integrity of the wall.

Work continues on evaluating the cause of the northern tailings facility embankment slump. A prohibition notice issued by the NSW Resources Regulator on depositing tailings in the northern tailings facility remains in place. As a precautionary measure, construction of the first 15-m lift of a 30-m-high temporary containment bund near the embankment slump has been completed. Work on the bund is expected to be completed in the coming two weeks. Mining from Panel Cave 1 is currently at a rate of approximately 11 mt/y.

Test and response production from Panel Cave 2 commenced as well. Newcrest expects to be at full mining rates within the coming weeks. Newcrest continues to progress evaluation and readiness of the Cadia Hill open pit as a tailings facility. The pit, in which mining has ceased, is approximately 500 m deep. Newcrest is progressing a permit to initially use the bottom 200 m of the Cadia Hill open pit for tailings storage and to use it in conjunction with the southern tailings facility to provide enough storage capacity to enable Cadia to return to full production. Preliminary reviews carried out by external specialists of the use of the Cadia Hill open pit as a tailings facility indicate that: The Cadia Hill open pit experiences very low inflows of groundwater and the geology is highly impermeable; and tailings would be fully contained within the pit without risk of release to adjacent waterways or environment. It remains too early for guidance to be updated.

As featured in Womp 2018 Vol 04 -