Waihi North Project Preliminary Site Investigation (Ground Contamination) Williamson Water & Land Advisory Limited iii contaminated areas are highly localised and if present, contaminants are highly likely to be low in volume compared to the scale of earthworks proposed. There are however appropriate processes that need to be put in place during disturbance to prevent localised effects and to comply with industry standards (refer earthworks requirements below). • A Site Management Plan (“SMP”) has been prepared to set out procedures to manage the above risks. The SMP is an indicative plan to support the resource consent application process for the WNP. It is anticipated that resource consent conditions will require a final Site Management Plan to be certified prior to the commencement of any earthworks activities (at any site). Investigation requirements [Section 5.2] In our view Detailed Site Investigations (“DSIs”) are not required at this stage given the low risk, localised nature and time between consent approval and actual soil disturbance occurring. For most areas within the WNP footprint where HAIL activities have been (or are more likely than not to have been) undertaken, the potential for adverse effects associated with soil disturbance and land use change is ‘Low’. Procedures for targeted investigation of these areas prior to bulk earthworks are specified in the SMP. These include procedures for the clearance of soil after demolition of buildings containing asbestos, removal of chemical storage areas including fuel tanks, actions for identifying offal pits and livestock dips via discussions with landowners and detailed inspection (potentially including pre-works soil testing) of current operational areas where upgrade works will be required. Once further specific information about any soil disturbance within the existing Processing Plant and Water Treatment Plant site is known, targeted soil investigations will be undertaken to inform disturbance activities where high-risk contamination may be present. The scope and methodology for undertaking these discrete soil investigations is provided in the SMP. Small changes to the SMP may result from these investigations and this will occur prior to commencement of the upgrade or expansion works. In addition, SMPs are intended to be live documents and further updates may occur throughout the works as additional investigations occur and works methods change. Consenting requirements [Section 5.3] • The WNP cannot comply with the permitted activity standards of NESCS Regulation 8(3). Without a DSI to facilitate a controlled or restricted activity consenting pathway, the soil disturbance associated with the WNP requires resource consent as a discretionary activity, pursuant to NESCS Regulation 11. Land use change can however be considered a permitted activity (pursuant to NESCS Regulation 8(4)) as it is highly unlikely that there will be a risk to human health or the environment if the activity is carried out. • If site remediation is necessary (unlikely, given the ‘Low’ soil contamination risks identified above) a resource consent will be required under Rule 5.3.4.8 of the Waikato Regional Plan (“WRP”) for the remediation. While it is unlikely that remediation will be required, if it is required, then it will not be supported by a DSI and therefore the WRP permitted or controlled activity provisions cannot be met. • A SMP to support a discretionary resource consent application under the NESCS and WRP has been prepared by WWLA under separate cover. Earthworks requirements [Section 5.4] Without soil sampling data and given the varied site conditions across the WNP area, specific mitigation measures cannot be finalised. However, based on our experience we expect: • Some asbestos control is likely to be necessary in the vicinity of current buildings that are intended to be demolished, predominantly dwellings. We recommend that asbestos testing be completed following the demolition of buildings containing Asbestos-Containing Material (“ACM”). • Soil sampling in the vicinity of buildings with ACM and other sources of contamination such as dangerous goods stores and workshops will be required to inform other targeted remediation/ earthworks management requirements. • While asbestos-contaminated soils (if any) will require disposal to landfill, any other contamination is expected to be able to be retained onsite and diluted through mixing with overburden, tailings or uncontaminated topsoil. • Standard earthworks controls and procedures are likely to be appropriate for implementation following any remediation that may be required, with emphasis on worker hygiene and preventing discharges of sedimentladen stormwater from site. • The SMP sets out procedures for managing and disposing of contaminated soil. It includes details of postdemolition investigation or validation processes, specific soil disposal measures, procedures for managing any unexpected discovery of ground contamination and health and safety protocols. Carrying out soil disturbance activities in general accordance with the SMP will ensure that human health is protected from the effects of soil borne contamination.
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