Why is Newmont drilling here?
Newmont recognises that the Waihi area has a long and bountiful history of mining and remains a very prospective area for further gold discovery and therefore continued mining. The company has made a decision to continue operating in the Waihi area – the key to this is the discovery of new gold resources. This is only achievable through further exploratory drilling.
What is a drilling rig used for?
In this area gold and silver are found in quartz veins. Exploration drilling is a way of determining the location and size of quartz veining. It allows the quartz to be sampled and assayed to accurately determine the gold and silver content of the vein system.
How do drilling rigs work?
Most of the rigs in this area are diamond drilling rigs. They use a diamond impregnated drill bit capable of boring through hard quartz. The drill bit bores a circular hole about 96mm diameter to produce 60 millimetre diameter drill core for analysis. The drill bit is screwed to the end of a 'string' of hollow steel rods. The rig's engine spins the drill string as it is pushed into the ground. Every three metres a new rod is added. As the drill string is spinning and penetrating the rock the core is left inside the drill rod. Every metre or so this core is pulled out through the inside of the rods and placed in boxes ready for analysis by geologists.
How deep do they drill?
In this area most holes are drilled to between 200 and 500m
Why so many drill holes?
Drill core of 60 millimetres diameter provides only a very small sample of the rock below surface. To gain enough knowledge, and with it confidence to identify an ore body, many holes may need to be drilled. This matrix of drill holes helps build a much clearer picture of the potential orebody.
What happens to the drill core?
The drill core is taken back to a core shed and laid out, so geologists can record the rock type from surface to the bottom of the hole. Sections of drill core that are potentially mineralised are split in half. One half is sent to a laboratory for analysis for gold and silver.
If there’s a rig in the
paddock
next door, where is it testing?
If you look at the mast of the rig and project that line into the ground, that will indicate the heading of the drill hole.
What controls are in place to ensure drilling rigs do not damage the environment?
• All drilling operations must comply with local council and Resource Management Act conditions and other conditions. These may specify hours of work, noise levels, areas of restricted operation and more.
• Newmont’s exploration procedures are written to ensure compliance with the consents and the various district plans, council regulations and government acts.
• Contractors must undertake an induction process that details Newmont’s environmental procedures and expectations, the various legislative requirements, and site environmental controls.
• Rigs are regularly inspected and monitored.
• All incidents are reported and recorded.
• Any affected owners or occupiers of land are consulted.
What happens to the
area after a rig leaves a site?
A crew will rehabilitate the site. Paddocks are returned to pasture by re-contouring and re-seeding. In bush areas the ground is layered with plant material such as manuka slash and native seedlings are planted.
