In 1972 WMC Resources Limited (WMC) discovered a near surface uranium and vanadium resource on the Yeelirrie Pastoral Station, approximately 110 km north-west of Leinster, Western Australia. Between 1972 and 1980 WMC undertook several phases of exploration and three trial mining programmes at Yeelirrie.

Detailed metallurgical studies were undertaken from 1980 to 1982 at a purpose-built pilot plant north of Kalgoorlie (the Kalgoorlie Research Plant ). Approximately 220,000 m³ of material was mined from the three slots, with some ore transported to the Kalgoorlie Research Plant for processing. Some mine overburden was used to provide a running surface on haul routes and access tracks. The majority of mine overburden was placed in five stockpiles. In March 1983 the project was placed on monitored care and maintenance.

Slot 1 prior to backfilling
(10 June 2004)

Slot 1 after backfilling
(28 August 2004)

In March 1996 WMC completed an environmental audit of the Yeelirrie Project Area and the former sample preparation facilities at the Yeelirrie Homestead. The audit highlighted deficiencies in several areas including site housekeeping, site security and reporting, adequacy of signage and management of radioactive materials.

An Environmental Improvement Plan was developed to action the audit findings and work on all potential non-conforming areas was completed in 1998. A monitoring and security programme was also established with results reported annually to the Department of Industry and Resources (DoIR).

A Provisional Closure Plan was prepared for the site in 2001 and the first phase of the programme, the capping of historic drill holes, was completed in 2002. A fourth amendment to the Radiation Management Plan (WMC, 2003a) was submitted in December 2003. It described rehabilitation activities to be undertaken within the Yeelirrie Project Area in 2004. The overall objective of the closure finalisation works was to leave the site in a safe and stable condition that poses a low risk of any future impact to the environment or health and safety of any person who may visit the site. Completion criteria for the proposed closure finalisation works were developed to satisfy a pastoral land use in accordance with the outcomes approved in the Draft Environmental Impact Statement (WMC, 1978).

Procedural and workplace controls employed during the closure finalisation works successfully managed worker radiation levels to below requirements. The environmental gamma radiation levels after rehabilitation of the Supervised Area meet the completion criteria.

Seed collection and revegetation works were completed between October and December 2004. The remaining open drill holes were capped in November 2004. The closure finalisation works have been completed to ensure that there is a low risk of environmental, health or safety impact post-closure. Closure objectives and completion criteria to satisfy a pastoral land use have been met.

Post-closure environmental and spot radiation monitoring will be undertaken to confirm the earthworks are stable, revegetation is successful and surface water movement is not significantly impeded. The principle tools for monitoring will be Ecosystem Function Analysis (EFA), area inspection and photo-monitoring points. Monitoring will be undertaken at sites located in the stockpile areas, miscellaneous disturbed areas and the three backfilled slots. Monitoring and inspections will be conducted annually for five years (2005 to 2009), or less, depending on the EFA results. Results of the EFA monitoring will be reported to the DoIR as an appendix to the Annual Environmental Report.