Cadia Tailings Storage Facility

Cadia Valley Operations (CVO) is a gold/copper mining and processing complex 25km south of the town of Orange, central west NSW. Cadia Holdings Pty Ltd (CHPL), a wholly owned subsidiary of Newcrest Mining Limited (NML), is the owner and operator of CVO.

The CVO complex comprises the Cadia Hill, Ridgeway and Cadia East mines, minerals processing facilities and associated infrastructure. Mining commenced in 1998, with current approvals taking the project through to 2031.

There were two operational tailings storage facilities (TSF) at CVO; the Northern TSF (NTSF) and the Southern TSF (STSF). Both TSF embankments were constructed across the former Rodds Creek, the NTSF being at the upstream location and the STSF at the downstream location. Construction of Stage 1 of the NTSF was completed in 1998, while construction of Stage 1 of the STSF was completed in November 2001. By mid-2007, tailings and decant water impounded by the STSF had commenced to encroach on the downstream toe of the NTSF.

The NTSF is a Prescribed Dam under the requirements of the NSW Dams Safety Act 1978, with the NSW Dam Safety Committee (DSC) being the administering authority. At the time of the failure, the NTSF was assigned a Consequence Category of Significant with an environmental approval for a final crest level of 779 mAHD.

In the late afternoon of Friday 9 March 2018, following the identification of cracks on the dam crest earlier in the day, a slump occurred on the western side of the southern embankment of the NTSF.