Waihi North Project Preliminary Site Investigation (Ground Contamination) Williamson Water & Land Advisory Limited 28 2.3 Environmental setting The environmental setting is described in Table 3. The features of the environmental setting are considered in the context of their potential to affect the distribution, mobility and form of contaminants (if present). These variables set the scene and inform the CSM evaluation (Section 4) if it is established that activities with the potential to cause ground contamination have occurred. Table 3. Environmental setting Topography Site topography influences where contaminants might migrate to if present. Topography is described for each area in Section 2.2. Generally speaking, the existing Processing Plant and WTP site and TSFs are relatively flat, with farmland at the Willows Road property and within the Park being undulating to hilly. Cut to fill operations would have been required to form the Processing Plant and WTP site with filling associated with the TSFs and rock stacks. All developed facilities have perimeter drains that feed into a range of water collection/retention ponds/systems. Surrounding land use Surrounding land may include HAIL activities that can contaminate soil or groundwater on properties nearby. The Processing Plant and WTP site, proposed NRS, proposed GOP and TSFs (existing and proposed) are all east of Waihi. The Willows Road property and the Park project components are located north of Waihi. Land immediately bordering these sites is for the most part rural/ farmland with isolated farm buildings (or, in the case of the project area in the Park, undeveloped and heavily vegetated). There are no significant sources of contamination on immediately surrounding land holdings. Geology Geological conditions are considered in the context of describing the CSM (Section 4) should a potential for contamination be identified by this desk study. For example, more porous soils can enable contaminants (if present) to move more quickly and potentially further than clay-rich soils that retain/bind or prevent penetration of contaminants. The project area is within the Coromandel Volcanic Zone, a 200 km volcanic arc of Miocene-Pliocene age and containing over 50 precious and base metal deposits. The WNP sits largely in Pliocene and Upper Miocene Whitianga Group rhyolites and dacites, as well as Coromandel Group andesites and dacites. Quaternary alluvial sediments form the shallow geological units in valley floors and near streams. A significant network of faults cross the area (Figure 10) and strongly influence the patterns and nature of mineralisation. Hydrothermal alteration minerals have replaced almost all volcanic minerals in the host rocks with the exception of quartz.
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