Waihi North Project Preliminary Site Investigation (Ground Contamination) Williamson Water & Land Advisory Limited 9 2.2.1 Processing Plant and Water Treatment Plant site (Existing) Processing facilities (existing), Figure 3: The Processing Plant and Water Treatment Plant (“WTP”) site service the Martha Pit to the north and Martha Underground Mine to the west. The Processing Plant and WTP site is accessed from the end of Baxter Road via a security-controlled access road. The Processing Plant is in the centre of the site with workshops to the south, ore and rock stockpiling areas to the west, the Martha Pit ore conveyor to the north and the WTP to the north of the conveyor. The existing facilities will be expanded but this will largely be within the existing footprint. Key features of the Processing Plant and WTP site are as follows: • The Processing Plant (Photograph 1) receives ore from the Martha Pit via the existing overland conveyor (Photographs 7, 13 and 17) that is first stockpile south of the conveyor. Ore from the Martha Underground Mine is also stockpiled in the same area. At the time of the inspection only the Martha Underground Mine was operating (portal shown in the background of Photograph 16). Surplus rock is currently being stockpiled in the Polishing Pond Stockpile to the north of the WTP (Photograph 18). • Gold and silver is recovered from ore through a Carbon-in-Leach (“CIL”) process which involves grinding and chemical leaching (Photograph 2), the key constituent of which is cyanide. Cyanide is obtained in powdered form in isotainers (Photograph 4) and made up into liquid form on site. Purple painted liquid storage tanks (approximately 100,000 L each) are part of the cyanide process area (Photograph 3). All above-mentioned chemical treatment and storage areas are bunded and paved with no evidence of significant spills or leaks. • Other chemical storage areas were observed throughout the wider Processing Plant and WTP site and included: - Waste oil drums are in the workshops (Photographs 9 and 10), with a collection area southeast of the Processing Plant (Photographs 5 and 6). Waste oil drums and oil-soaked debris in portable bins are stored in a timber framed corrugated iron plant building with an inbuilt oil collection tray. - Portable diesel storage tanks (up to 20,000 L each) (Photographs 7 and 8) are located adjacent to the Favona portal and the conveyor. - Components of explosives used within the mines are stored separately for safety purposes. Magazines are stored in the northwest of the processing area while IBCs storing ammonium nitrate are stored to the northwest of the WTP (Photograph 18). - Chemicals for water treatment processes are stored at the WTP (Photograph 14). - Several gas bullets are present around the site, one at the WTP and another near the training rooms and staff amenities building. - Overall, the chemical storage areas were observed to be well maintained to current standards, although we note we have not undertaken a full assessment in accordance with the HSNO Act. • Workshops, including electrical and mechanical, are in the south of the Processing Plant and WTP site. Mines rescue also has a building in this area (Photograph 11). The workshops are generally corrugated iron construction although several half round steel framed canvas clad workshop areas are around the peripheries of the southern part of the process area (Photograph 10). Most workshops have a sealed concrete floor although some are hardfill. Grassed public reserve bounds the southern side of this area (Photograph 16). • Stormwater, including discharges from the Martha Underground Mine, are collected in a series of ponds around the eastern side of the processing area. These are directed to the WTP. Ponds and drains are predominantly synthetically lined, although unlined drains and ponds also occur (Photographs 11 and 12). • The WTP is immediately north of the conveyor (Photograph 13). It receives water from the process area, the rock stockpiles and TSF’s (overflow and underdrainage systems). Water is treated via a series of chemical treatment and clarification processes in tanks before being polished in two lined open ponds to the east of the WTP (Photograph 15). Chemical storage and tank compounds are concreted with gravel surrounds. • A single electrical transformer was noted adjacent to the conveyor plant (Photograph 17) although it is expected other similar transformers may occur in other areas, i.e., associated with the site wide electrical infrastructure.
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