Coal is a valuable energy source in New Zealand and has been mined from the
West Coast for over 100 years. Stockton Mine is New Zealand's largest opencast
coal producer supplying around 1.5 Mt of hard coking and thermal coal to
international markets annually.
The Stockton Plateau forms an extensive, gently inclined dip slope on erosion
resistant Lower Eocene Brunner Coal Measures unconformably overlying basement
rocks. The dip slope rises 600 - 1000 masl, locally dissected by fault scarps
and present-day fluvial systems, some of which are deeply incised. Within the Mt
Augustus Mining Block overburden comprises of a 30 - 40 m thick sequence of
fluviatile, coarse to granular coal measure sandstones. High quality coking coal
is preserved as a gently dipping, 10 - 12 m thick seam. High and sometimes very
steep cliffs of jointed overburden shape the skyline escarpment, above steep
forested slopes and gullies.
As mining has progressed at Mt Augustus individual coal blocks are
progressively becoming more technically challenging. This paper outlines the
scientific approach taken by Solid Energy International and mining contractors
to carefully unlock many thousands of tons of coal whilst protecting nearby
flora and fauna from the impacts of dislodged rock and other blasting
side-effects.
The strategy involved:
an expert-driven onsite risk assessment,
formulation of a management plan to manage impacts,
conducting an in situ vibration research program, and
analysis of results and operational
designs to eliminate potential environmental problems.