The KSM Project development includes a 165 m high asphalt core, rock-fill Water Storage Dam (WSD) that will contain mine site run-off and a Tailings Management Facility (TMF) that will be developed as a set of contiguous, cycloned tailings sand retention structures with a maximum height of 240 m, to ultimately contain 2.2 billion tonnes (Bt) of tailings. The focus of the Board is the structural stability, integrity, capacity and associated environmental impacts of these two dam structures. A proportion of the 3 Bt of waste rock to be stored in the Rock Storage Facility (RSF) contains sulphides that have potential for acid generation (PAG) and yielding acid rock drainage (ARD). While the RSF pile stability and management program and control of ARD within the RSF as well as from within the mine workings, are not primarily within the scope of the Board’s review, the management of contact waters that contribute to the diversions, collection and storage facilities associated with the WSD are within scope. The RSF drains into the WSD.
The purpose of the Board is to:
- Provide independent opinion as to whether the TMF and WSD, including all pertinent control structures or systems, meet accepted design and operational guidelines based on internationally accepted practices;
- Provide advice and guidance on technical issues associated with the design, construction, operation and maintenance and closure of the TMF and WSD, including all pertinent control structures and systems. This includes commenting on the site characterization programs that will be undertaken to advance the project through Feasibility Studies and into construction; and
- If the Board considers it warranted, make recommendations regarding improvements to the structures or systems that will enhance the safety and/or longevity of the structures and reduce risks posed by the structures during construction, operations and closure.
At the time of this review site selection and dam section profiles, as well as most tunnel and access routings had been determined. Pre-feasibility designs have been prepared to a level that allows Feasibility Design requirements to be established.
The primary objective of the March 2015 meeting was to introduce the Board members to the KSM project and the site conditions, brief them on completed site investigations, design bases and analyses, trade-off studies, siting and facility elements selection, and preliminary results that were leading to decisions. In addition to requesting the Board to provide its general observations and recommendations, SG/P posed the following five specific questions to the Board:
- Are the dams and major structures appropriately located?
- Are dam sections, materials, construction methods and sequencing appropriate for the site and purpose?
- What, in the opinion of the Board, are the greatest design, construction and operating risks?
- Are the facilities designed to operate effectively?
- Are the facilities designed to be safe?
The information provided to, and the depth of review conducted by the Board has been sufficient to provide responses to the above questions and the Board’s observations and recommendations contained in this report. Information has been provided to the Board in the form of copies of relevant reports, presentations made by SG/P and KCB and the Board’s general discussions held with the KSM Project personnel during the course of the review.
For the key findings of the Board from this review, the reader is referred to Section 2 of this report.
The responses to SG/P posed questions are provided in Sections 4.7 and 5.6.