The Pike River Coal Mining Company awarded McConnell Dowell the design and construct (D&C) contract for Pike River Coal Mine Project, which is located within the confines of the Paparoa National Park, 46 km east of Greymouth on New Zealand’s South Island.

The mine will produce 1 million tonnes of hard coking coal per annum for the next 20 years. McConnell Dowell's works included the construction of a 2.3 km mine access tunnel, associated passing bays and sumps for this landmark project.

The D profiled tunnel was excavated at various inclined grades to pass under located surface features. It measures 5.5 m wide by 4.5 m high. Ancillary works included construction of a 165 m high, 4 m2 ventilation shaft, a full length conveyor and support systems at the portal.

Drill and blast methods were used to construct the tunnel. Mucking was done by one and sometimes two 14 t capacity LHDs carting to a tunnel conveyor. Shotcreting of the tunnel roof and walls was done using fibre shotcrete transported from Greymouth to site in a specialised tunnel agitator truck. It was sprayed on with a robotic shotcreter.

The MacDow team overcame a number of major challenges on the project using unique construction solutions. Unexpected rock conditions encountered early in the project were overcome with the procurement of specialised equipment to ensure the project program was maintained.

The high altitude of the project site also presented a challenge. The top of the ventilation shaft, covered in snow and subject to high winds during winter, could only be constructed during peak summer, and could only be accessed by helicopter.

MacDow respected the cultural and environmental sensitivities associated with working inside a national park. Works were planned to avoid the clearing of significant native flora. The cultural beliefs of the local indigenous community were respected with bans on the drawing of water from local waterways.