WAI-985-000-REP-LC-0056 Revision 0 Page 7 of 21 Waihi North Project – Tailings and Rock Storage – Functional Need Assessment OGNZL recognises that the National Policy Statement for Freshwater Management 2020 (“NPSFM”) provides direction to avoid the loss of river extent and values unless there is functional need for the activity to be located there.1 The RMA defines the term “river” as follows: • r iver means a continually or intermittently flowing body of fresh water; and includes a stream and modified watercourse; but does not include any artificial watercourse (including an irrigation canal, water supply race, canal for the supply of water for electricity power generation, and farm drainage canal) The NPSFM defines the term “functional need” as follows: • funct ional need means the need for a proposal or activity to traverse, locate or operate in a particular environment because the activity can only occur in that environment The purpose of the functional need assessment is to demonstrate that TSF3, GOP and GOP TSF, NRS and WRS, as integral components of the Waihi North Project, are not only the preferred options, but have a functional need to be located in the respective environments in which they are proposed. In assessing the functional need for the proposed features to be in the environments in which they are identified, OGNZL has considered a range of factors including: • Land ownership/control – features can only be located on land which the company owns or controls and which is available for development (e.g., does not contain existing infrastructure). • Scale – features must be at sufficient scale to accommodate the required volumes of material meaning that down-scaling to avoid sensitive areas (in this case rivers) may be impractical while still retaining adequate storage space. • Material movement costs – features must be located close to the places from which the material they are constructed from is sourced. Moving large volumes of material significant distances is economically inefficient and gives rise to additional and unnecessary effects (including amenity effects; air discharge effects; and carbon emissions). • Geotechnical and hydrogeological – features must be located on suitable foundations to manage stability and groundwater. • Water management – potentially affected surface and groundwater resources must be capable of management. This includes an ability and space to construct water management infrastructure (silt ponds, drains etc) and to maintain safe separation distances from sensitive waterbodies (wetlands; Ohinemuri River etc). • Construction efficiency – the use of existing landforms and contours (such as gullies) can significantly reduce the scale and volume of materials needed to construct storage impoundments, impacting the feasibility of construction using available volumes of rock and clay, time and cost to construct and emissions produced in the process. These factors are assessed in the follow sections. 1 The NPSFM also requires the effects of such activities to be managed by applying the effects management hierarchy. This requirement is addressed in Boffa Miskell (2022).
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