Located under the Paparoa Range on New Zealand’s South Island, the Pike River development is planned to reach first coal in July 2008 and full production during mid-2009.

Once coal is reached via a 2300m tunnel, the mine will employ a hydraulic mining method – which involves using high-pressure water from a hydraulic monitor (essentially water cannon) to cut and transport coal from either side of a pre-driven roadway.

Pike River today announced it has driven the tunnel 2085m and is 8m from the Hawera fault zone.

The Hawera fault is a major reverse fault marking the change from hard rock (gneiss) to sedimentary shales, sandstones and coal measures.

Pike River said previous drilling of the fault zone indicated "quite variable conditions" with crushed zones immediately adjacent to the fault.

Pike River and tunnelling contractor McConnell Dowell have implemented a number of measures to safely tackle the fault.

Prior to advancing the tunnel closer than 50m from the fault, gas monitoring equipment was installed on the drilling jumbo and in the general roadway ventilation.

Installed electrical equipment was replaced with coal mine compliant flameproof electrical equipment and advance drillholes were drilled to check for both gas and water accumulations.

Pike River said now it was 8m from the fault, advance drilling had started to produce sufficient methane from the fault zone to instigate the planned changeover of equipment to flameproof tunnelling equipment.

“No water has been evident to date from these drillholes," Pike River said.

“Over the next few weeks prior to advancing through the fault, the last remaining concreting and civil works in pit bottom will be completed and the equipment changeover, such as replacing the jumbo drilling unit with Pike River’s road header, will be undertaken.

“This equipment is purpose built for use in sedimentary coal measures and where methane gas may be present and is onsite and ready for installation."

Pike River has pre-fabricated steel sets to be erected if required to support the tunnel roof through the forecast 50m crushed zone after the fault.

The company has forecast a slower rate of tunnelling through the area, which is expected to be traversed during June.

The tunnel is expected to intersect the coal seam in July 2008.