Rehabilitation costs
The net present value of estimated future rehabilitation costs is provided for in the consolidated financial statements and capitalized within property, plant and equipment on initial recognition. Rehabilitation will generally occur on closure or after closure of a mine. Initial recognition is at the time of the construction or disturbance occurring and thereafter as and when additional construction or disturbances take place. The estimates are reviewed annually to take into account the effects of inflation and changes in estimated risk adjusted rehabilitation works cost and are discounted using rates that reflect the time value of money. Annual increases in the provision due to the unwinding of the discount are recognized in the consolidated statement of comprehensive income as a finance cost. The present value of additional disturbances and changes in the estimate of the rehabilitation liability are recorded to mining assets against an increase/decrease in the rehabilitation provision. The rehabilitation asset is amortized on a unit of production basis. Rehabilitation projects undertaken, included in the estimates, are charged to the provision as incurred. Environmental liabilities, other than rehabilitation costs, which relate to liabilities arising from specific events, are expensed when they are known, probable and may be reasonably estimated.
