Responsible Mining 101: Recommended Practices 3 - Part 8

New technological advances and the use of preventive measures can reduce the environmental impacts of drilling. Drilling is the process of making a hole into a hard surface where the length of the hole is very large compared to the diameter. In the context of mining engineering, drilling refers to making holes into a rock’s mass. According to the Australian mines atlas, drilling is used to obtain very detailed information about rock type, mineral content, rock fabric and the relationships between rock layers close to the surface and at depth.

The type of drill bit used in mining is dependent on the type of drilling being done. There are three types of drilling:

1. Percussion drilling – uses steel rock bits of various designs to break up the rock while drilling.

2. Reverse circulation- these drills produce rock cuttings at the bit which are blown up the hole by compressed air. The cuttings are separated from the air or water by a cyclone or cyclone-splitter combination.

3. Diamond drilling-using large machines is the preferred method of delineating mineralization. Diamond drills produce core which ranges from approximately one to two inches in diameter.

Drilling is one of the most intrusive aspects of exploration. However, technological advances such as higher maneuver-ability and productivity of drilling rigs, have the potential to significantly reduce the impacts of drilling. Lighter rigs reduce ground compaction and allow transport by helicopter. Increased efficiency of drilling equipment means less time spent on the site and rehabilitation can start and end faster. Drilling during the dry season reduces soil compaction and the potential for future erosion.

When positioning drill holes and excavations, companies should be aware of areas that are environmentally or culturally sensitive, as identified in a pre-exploration baseline study or the Environment Impact Assessment. Drill pads should be constructed with a nearby low drainage collection area known as sump, to catch drainage from the storage of fuel, oil and drilling fluid supplies. The sump should be located downhill from the drill rig, and may need plastic lining, depending on the geology. Drilling fluids should be recycled where possible, using separators to recover from the drilling mud and cuttings.

Drilling equipment, including rigs and transport machinery, should be maintained in good condition to prevent oil leaks and spills, all equipment should be cleaned before using in a new area, as soul or traffic movement can spread noxious weeds and kill local wildlife and plants.

The transport and storage of fuel and lubricants for drilling equipment must also be handled with care. Fuel and lubricants should be isolated in protected containers to prevent spillage and they should be disposed of off-site according to the area’s regulations.

The refuelling or maintenance of equipment should be avoided over natural water drainage lines and in sensitive habitats. Furthermore, all drill rigs should have fire extinguishers and efficient exhaust pipes to reduce potential for destructive brush fires. Equipment maintenance, fueling and transport should be avoided during storms because rain exacerbates soil and contaminant movement into waterways.