Waihi North Project Preliminary Site Investigation (Ground Contamination) Williamson Water & Land Advisory Limited 29 Figure 10 Published geology of the WNP area (Source: Edbrook, SW (compiler) 2001, GNS Geological Map 3). Hydrogeology Hydrogeological conditions affect the potential risk of contaminants (if present) entering and being transported in groundwater. Depth to groundwater will be highly variable across the project area. Groundwater is most likely to be impacted in tunnelling activities and within the Gladstone Open Pit and is highly unlikely to be intercepted by shallow ground improvement works on the remainder of the project. Surface water bodies Surface water features are potential receiving environments should contaminants be present on a site. Processing Plant and WTP/NRS/GOP/TSFs sites: The Ohinemuri River flows between the Processing Plant and WTP site and the NRS and TSFs, and to the south and west of the GOP site. Other key surface water features are the Waione Stream and Ruahorehore Stream to the south of the TSFs. These features are shown on Figure 11. Coromandel Forest Park and Willows Road property: Multiple streams are located within both sites. The streams on the farm and immediately adjacent DOC land are observed at low elevations and flow towards the east, draining into the Waihou River (via the Ohinemuri River) which then discharges into the Firth of Thames, approximately 50 km away. Streams in the area of the tunnels and mine within the Coromandel Forest park flow eastward, discharging to the Pacific Ocean at Whiritoa and Whangamata. Figure 11. Open water courses (blue) around the Processing Plant and WTP, NRS, GOP, existing TSFs and TSF3. (Source: LINZ). Sensitive receptors Sensitive environmental receptors could include aquatic or terrestrial ecosystems. This is not an ecological assessment but is instead an initial review of the surrounding environment to assess where contaminants (if present) on the site could migrate to and the specific receptors potentially affected. Sensitive human receptors could, for example, be children at a school or kindergarten on or adjacent to a site. Workers on industrial land (on or adjacent to a site) would be considered less sensitive. This people receptor interpretation informs the CSM and future guideline value selection for evaluation of soil data. The key sensitive receptors surrounding the WNP areas are: • The residents of Waihi and surrounding farms; • Terrestrial and aquatic ecosystems such as the Ohinemuri River, Waione and Ruahorehore Streams and the Park.
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