Completion criteria - Case studies considering bond relinquishment and mine decommissioning: Western Australia

The Western Australia Government Agencies controlling environmental bond assessment and land relinquishment after mine decommissioning advocate proactive environmental management. Meeting environmental objectives ensures return of bond monies and facilitates release of the Company from environmental obligations. Completion criteria that confirm establishment of a self-perpetuating and resilient vegetation cover over mine waste are being developed. Post-mining land use generally reverts to maintaining the natural ecosystem or rangeland. Within this climatic zone very distinct vegetation communities are closely linked to soil substrate classification. Matching surface waste characteristics from a mine waste dump with those of surrounding analogue communities is the first step in determining an achievable vegetation cover. Examples of the methodology as applied to one Western Australian mine site, a semi-arid location (annual rainfall 320 mm) (Westonia - 31 degrees 18'5, 118 degrees 42'E) is presented. There has, at Westonia, been establishment of Eucalypt Woodland on mildly saline waste surfaces. The combination of direct seeding at the appropriate sowing time and good topsoil management, has led to successful revegetation of a suite of species with all life forms represented.