To the Board of Directors, Management and stakeholders of OZ Minerals Limited:
OZ Minerals Limited (OZ Minerals) commissioned Net Balance Management Group Pty Ltd (Net Balance) to carry out a limited assurance engagement of selected sustainability performance data (the ‘performance data’) disclosed in the organisation’s 2011 Sustainability Report (Report). The Report presents OZ Minerals’ sustainability performance over the period 1 January 2011 to 31 December 2011.
The objective of the assurance engagement was to state whether anything had come to our attention that would cause us to believe, based on our limited assurance procedures, that the performance data contained within the Report had not been prepared and presented, in all material respects, in accordance with relevant legislation, internal criteria or Global Reporting Initiative (GRI) indicator protocols.
OZ Minerals’ management were responsible for the preparation and presentation of the Report. This statement represents the assurance provider’s independent opinion. Net Balance’s responsibility in performing its assurance activities was to the management of OZ Minerals alone and in accordance with the terms of reference agreed with them. We disclaim any assumption of responsibility for reliance on this assurance statement or on the subject matter to which it relates, to any person other than the management of OZ Minerals, or for any purpose other than that for which it was prepared. Other stakeholders should perform their own due diligence before taking any action as a result of this statement.
Assurance Standard and Scope
The assurance engagement was conducted in accordance with Australian Standards on Assurance Engagements ASAE3000 Assurance Engagements other than Audits or Review of Historical Financial Information (‘ASAE3000’) issued by the Australian Auditing and Assurance Standards Board. The engagement covered the following in the Report:
- Limited assurance of data and statements contained in the ‘Performance Summary 2011’ table
- A Global Reporting Initiative (GRI) G3.1 Application Level Assessment.
The level of assurance provided was limited, as defined in the ASAE3000. The criteria for the engagement were the relevant Australian legislation, internally developed criteria and GRI indicator protocols.
Because of the inherent limitations of any internal control framework and underlying data, it is possible that fraud, error or non-compliance may occur and not be detected. A limited assurance engagement under ASAE3000 is restricted primarily to enquiries and analytical procedures and the work is substantially less detailed than undertaken for a reasonable assurance engagement. As such the level of assurance is lower than would be the case for a reasonable assurance engagement under ASAE3000. Accordingly, we have expressed our conclusion on the above basis.
Additionally, non-financial performance data may be subject to more inherent limitations than financial data, given both its nature and the methods used for determining, calculating and sampling or estimating such data. In some instances we found that internally developed criteria were unavailable. Where this was the case, guidance from the GRI framework was used to assess the suitability of the collection and calculation of performance data.
Net Balance's assurance methodology consisted of evaluating the reliability of the performance data through the review of systems, processes, information and calculations used to support the data. The procedures selected depend on the assurance provider’s judgement, including assessment of the risks of material misstatement of the performance data prepared by OZ Minerals. In making judgements, consideration was given to the internal controls relevant to the calculation and collection of the performance data.
Evidence gathering for the evaluation of reliability and accuracy of performance data involved the following:
- Interviews with data owners to understand the performance data metric definitions, data sources, reliability of data, completeness of data and the basis for significant assumptions used in reporting of performance. Particular attention was paid to the consistency with recognised published standards and guidelines.
- Interviews with key personnel to obtain an understanding of the systems and the process used for recording, collation and retention of performance data.
- Review of internal and IT controls relevant to the calculation of the performance data.
- Re-performing calculations for a sample of metrics.
- Collection and evaluation of supporting documentary evidence.
The assurance engagement was undertaken between January and March 2012 and the procedures took place at OZ Minerals’ head office in Melbourne and Prominent Hill site.
Net Balance has not had any part in collecting and calculating the performance data, or in drafting Report content. During the reporting period Net Balance also provided assurance over OZ Minerals’ National Greenhouse and Energy Reporting (NGER) submission. As these services were of an audit nature, they are complimentary to this engagement and do not impact upon Net Balance’s independence. Net Balance confirms that we are not aware of any issue that could impair our objectivity in relation to this assurance engagement. Further, in conducting this assurance engagement Net Balance has met the independence requirements of our Independence Policy. The Net Balance assurance team has the required competencies and experience to conduct this engagement.
Limited Assurance Conclusion
Based on our limited assurance procedures, nothing has come to our attention that causes us to conclude that the performance data (as described above), has not been prepared, in all material respects, in accordance with the relevant legislation, internally developed criteria or GRI indicator protocols. Net Balance also confirms that the GRI Application Level check classified the Report as B+.
On behalf of the assurance team
22 March 2012
Associate Director, Net Balance & Lead CSAP