Policy for close down, restoration and environmental clean up, estimates – mining operations

Rio Tinto plc – Annual report – 31 December 2017

Industry: mining

1 Principal accounting policies (extract)

(k) Close-down, restoration and environmental obligations (note 26)

The Group has provisions for close-down and restoration costs which include the dismantling and demolition of infrastructure, the removal of residual materials and the remediation of disturbed areas for mines and certain refineries and smelters. These provisions are based on all regulatory requirements and any other commitments made to stakeholders.

Closure provisions are not made for those operations that have no known restrictions on their lives as the closure dates cannot be reliably estimated. This applies primarily to certain Canadian smelters which have indefinite-lived water rights or power agreements for renewably sourced power with local governments.

Close-down and restoration costs are a normal consequence of mining or production, and the majority of close-down and restoration expenditure is incurred in the years following closure of the mine, refinery or smelter. Although the ultimate cost to be incurred is uncertain, the Group’s businesses estimate their costs using current restoration standards and techniques.

Close-down and restoration costs are provided for in the accounting period when the obligation arising from the related disturbance occurs, based on the net present value of the estimated future costs of restoration to be incurred during the life of the operation and post closure. Where appropriate, the provision is estimated using probability weighting of the different remediation and closure scenarios. The obligation may occur during development or during the production phase of a facility.

Provisions for close-down and restoration costs do not include any additional obligations which are expected to arise from future disturbance.

The costs are estimated on the basis of a closure plan, and are reviewed at each reporting period during the life of the operation to reflect known developments. The estimates are also subject to formal review, with appropriate external support, at regular intervals.

The initial close-down and restoration provision is capitalised within “Property, plant and equipment”. Subsequent movements in the close-down and restoration provisions for ongoing operations, including those resulting from new disturbance related to expansions or other activities qualifying for capitalisation, updated cost estimates, changes to the estimated lives of operations, changes to the timing of closure activities and revisions to discount rates are also capitalised within “Property, plant and equipment”. These costs are then depreciated over the lives of the assets to which they relate. Changes in closure provisions relating to closed operations are charged/credited to “Net operating costs” in the income statement.

Where rehabilitation is conducted systematically over the life of the operation, rather than at the time of closure, provision is made for the estimated outstanding continuous rehabilitation work at each balance sheet date and the cost is charged to the income statement.

The amortisation or “unwinding” of the discount applied in establishing the provisions is charged to the income statement in each accounting period. The amortisation of the discount is shown within “Finance items” in the income statement.

Environmental costs result from environmental damage that was not a necessary consequence of operations, and may include remediation, compensation and penalties. Provision is made for the estimated present value of such costs at the balance sheet date. These costs are charged to “Net operating costs”, except for the unwinding of the discount which is shown within “Finance items”.

Remediation procedures may commence soon after the time the disturbance, remediation process and estimated remediation costs become known, but can continue for many years depending on the nature of the disturbance and the remediation techniques used.

Critical accounting policies and estimates (extract)

(iv) Close-down, restoration and environmental obligations (note 26)

Provision is made for close-down, restoration and environmental costs when the obligation occurs, based on the net present value of estimated future costs required to satisfy the obligation. Management uses its judgment and experience to determine the potential scope of closure rehabilitation work required to meet the Group’s legal, statutory and constructive obligations, and any other commitments made to stakeholders, and the options and techniques available to meet those obligations and estimate the associated costs and the likely timing of those costs. Significant judgment is also required to determine both the costs associated with that work and the other assumptions used to calculate the provision. External experts support the cost estimation process where appropriate but there remains significant estimation uncertainty.

The key judgment in applying this accounting policy is determining when an estimate is sufficiently reliable to make or adjust a closure provision.

Closure provisions are not made for those operations that have no known restrictions on their lives as the closure dates cannot be reliably estimated. This applies primarily to certain Canadian smelters which have indefinite-lived water rights or power agreements for renewably sourced power with local governments.

Cost estimates are updated throughout the life of the operation; generally cost estimates must comply with the Group’s Capital Project Framework once the operation is ten years from expected closure. This means, for example, that where an Order of Magnitude (OoM) study is required for closure it must be of the same standard as an OoM study for a new mine, smelter or refinery. As at 31 December 2017, there are ten operations with remaining lives of under ten years before taking into account unapproved extensions; the largest of these is Rio Tinto Kennecott for which a pre-feasibility study is expected to be concluded in the next 24 months. Adjustments are made to provisions when the range of possible outcomes becomes sufficiently narrow to permit reliable estimation. Depending on the materiality of the change, adjustments may require review and endorsement by the Group’s Closure Steering Committee before the provision is updated.

In some cases, the closure study may indicate that monitoring and, potentially, remediation will be required in perpetuity. In this case, the provision may be restricted to a period for which the costs can be reliably estimated; on average this is around 30 years for operations in closure.

The most significant assumptions and estimates used in calculating the provision are:

  • The weighted average remaining lives of operations is shown in note 26 c). Some expenditure may be incurred before closure whilst the operation as a whole is in production. The length of any post closure monitoring period will depend on the specific site requirements; some expenditure can continue into perpetuity.
  • The probability weighting of possible closure scenarios. The most significant impact of probability weighting is at the Pilbara operations (Iron Ore) relating to infrastructure and incorporates the possibility that some infrastructure may be retained by the relevant State authorities post closure. The assignment of probabilities to this scenario reduces the closure provision by US$0.7 billion.
  • Appropriate sources on which to base the calculation of the risk-free discount rate. At 31 December 2017 the carrying value of the close-down, restoration and environmental provision was US$9,983 million. The change in carrying value of the provision which would result if the real discount rate was 0.5 per cent lower than that assumed by management is shown in note 26.

There is significant estimation uncertainty in the calculation of the provision and cost estimates can vary in response to many factors including:

  • Changes to the relevant legal or local/national government requirements and any other commitments made to stakeholders;
  • Review of remediation and relinquishment options;
  • Additional remediation requirements identified during the rehabilitation;
  • The emergence of new restoration techniques;
  • Change in the expected closure date;
  • Change in the discount rate and;
  • The effects of inflation.

Experience gained at other mine or production sites may also change expected methods or costs of closure, although elements of the restoration and rehabilitation of each site are relatively unique to a site. Generally, there is relatively limited restoration and rehabilitation activity and historical precedent elsewhere in the Group, or in the industry as a whole, against which to benchmark cost estimates.

The expected timing of expenditure can also change for other reasons, for example because of changes to expectations around ore reserves and mineral resources, production rates, renewal of operating licences or economic conditions.

As noted in note (k) above, changes in closure and restoration provisions for ongoing operations (other than the impact relating to current year production) are capitalised and therefore will impact assets and liabilities but have no impact on equity at the time the change is made. However, these changes will impact depreciation and the unwind of discount in future years. Changes in closure estimates at the Group’s ongoing operations could result in a material adjustment to assets and liabilities in the next 12 months.

Changes to closure cost estimates for closed operations, and changes to environmental cost estimates at any operation, would impact equity, however, the Group does not consider that there is significant risk of a change in estimates for these liabilities causing a material adjustment to equity in the next twelve months. Any new environmental incidents may require a material provision but cannot be predicted.

Cash flow estimates must be discounted at the risk free interest rate if this has a material effect on the provision. The selection of appropriate sources on which to base the calculation of the risk-free discount rate requires judgment. The two per cent real rate currently used by the Group is based on a number of inputs including observable historic yields on 30 year US Treasury Inflation Protected Securities (“TIPS”), and recommendations by independent valuation experts. These inputs are considered in the broader global context that spot yields remain volatile and somewhat depressed in response to macroeconomic turbulence in recent years.

26 Provisions (including post-retirement benefits) (extract)

(c) The Group’s policy on close-down and restoration costs is described in note 1(k) and in paragraph (iv) under “Critical accounting policies and estimates” on pages 126 and 129. Close-down and restoration costs are a normal consequence of mining, and the majority of close-down and restoration expenditure is incurred in the years following closure of the mine, refinery or smelter. Remaining lives of operations and infrastructure range from one to over 50 years with an average for all sites, weighted by present closure obligation, of around 20 years (2016: 16 years). Although the ultimate cost to be incurred is uncertain, the Group’s businesses estimate their respective costs based on current restoration standards and techniques. Provisions of US$9,983 million (2016: US$8,722 million) for close-down and restoration costs and environmental clean-up obligations are based on risk adjusted cash flows. These estimates have been discounted to their present value at a real risk free rate of 2 per cent per annum, based on an estimate of the long-term, risk free, pre-tax cost of borrowing. If the risk free rate was decreased by 0.5 per cent then the provision would be US$1,102 million higher.

Non-current provisions for close down and restoration/environmental expenditure include amounts relating to environmental clean-up of US$336 million (2016: US$366 million) expected to take place between one and five years from the balance sheet date, and US$839 million (2016: US$727 million) expected to take place later than five years after the balance sheet date.

Close-down and restoration/environmental liabilities at 31 December 2017 have not been adjusted for amounts of US$75 million (2016: US$110 million) relating to insurance recoveries and other financial assets held for the purposes of meeting these obligations.

 

 

 

 

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