The Upper Waimangaroa mining permit is part of the Buller Coalfield and
lies on the eastern side of the Stockton-Denniston Plateau. The mining permit
area is estimated to contain a total in-ground coal resource of 58 million
tonnes, contained within 13 separate coal resource .blocks. The coal is
Bituminous High Volatile B rank with export potential as semi soft coking or
thermal coal. The Northern Opencast mine is the first mine proposed for Upper
Waimangaroa and consists of the three resource blocks at the northern end of the
permit area. The highwall of the mine will cut into the Mt William Range
resulting in overburden cover of up to 150 metres in some areas. The ability to
rehabilitate the area after mining was a major consideration in the design of
the mine. The Northern Opencast area has been geologically mapped, extensively
drilled and effectively modelled using Vulcan software. Three distinct coal
seams are present and the mineable in situ resource is estimated at 8.7 million
tonnes of which approximately 7.1 million tonnes is likely to be recoverable. It
is proposed that this resource will be mined using opencast methods and the void
will be backfilled with overburden. The life of the mine is at this stage
estimated at 19 years based on an annual production of 500,000 tonnes at 1.8%
sulphur and the Upper Waimangaroacoal will be blended with low sulphur coal from
the Greymouth Coalfield to meet export specifications. The Northern Opencast
area contains a range of native flora and fauna and physical features which make
it an environmentally significant area. Mining will totally modify the area,
thus an effective rehabilitation scheme is an integral part of the mine plan.
Various rehabilitation methods will be used, and wherever possible, the
backfilled areas will be rehabilitated so as to resemble the original area as
closely as possible.