Coal mining ceased at Strongman
Mine this year after 70 years of production. Underground mining finished in 2003
and opencast methods began in 1998. During the life of the mine, 8 million
tonnes of coal was extracted from two underground mines and 1.2 million tonnes
removed through opencast methods. Strongman Mine is within the Grey Coal Fields;
various seams have been extracted from the Rewanui Coal Measures. Coal extracted
was predominantly of thermal or semi-soft specifications and characterised by
low sulphur and low ash.

The area has steep topography,
high rainfall (>3000 mm/yr) and is particularly exposed to westerly quarter
winds. Strongman 1 and 2 underground mines are located in the steep, narrow
valley which leads to the Strongman Opencast at the top of the valley.
Subsidence from underground mining combined with spontaneous combustion, has
resulted in an underground fire which has had substantial surface effects.
Opencast mining in the steep topography resulted in several landslides at the
perimeters of the site. These factors, along with water management, topsoil
management and erosion control have added to the complexity of rehabilitating
the site.

Rehabilitation of the site is
well underway, including infrastructure removal, final landform creation and
revegetation of the Strongman Opencast footprint (~45 hectares). Some innovative
methods of rehabilitation have been trialled. Successful trials such as
helicopter-seeding and moss hydro-seeding on highwalls are now routinely used
along with traditional revegetation practices. 18 hectares disturbed land has
been replanted with 88 000 seedlings, and another 200 000 seedlings are
scheduled for planting over the three years. Fire management is an ongoing
challenge; however thermal photography shows a steady decrease in hot areas
which have been contained by grout curtains.

Mine closure is some time away
and will occur after all standards set by Solid Energy and regulatory bodies are
achieved.