Awaba seeks mine life extension

CENTENNIAL Coal is seeking to extend the life of its Awaba underground mine, west of Lake Macquarie in New South Wales, by four years until 2015 and lift production at the mine by 10% to 880,000 tonnes per annum.

Lou Caruana

In its environmental assessment submitted to the NSW Department of Planning, the company said mining operations started at the Awaba Colliery in 1947, prior to the commencement of any planning controls, and have continued without abandonment since that time.

“Thus, mining at the Awaba Colliery is not presently carried out under any existing planning approval,” the company said.

Centennial wants to extract coal from existing approved mining areas, extend the Stage 3 mining area and develop the East B mining area to produce a total of 880,000tpa of run-of-mine coal.

It also wants to expand the mine’s pollution control dam and continue coal delivery to the Eraring Power Station and Newstan Colliery.

Awaba generates $4.2 million a year in state royalties and approximately $20 million a year was paid out by the mine in “colliery invoices”.

Awaba operates 24 hours per day, seven days per week, and employs approximately 100 staff and contractors.

The company plans to continue using the mine’s surface infrastructure, including processing and transport systems and has pledged to rehabilitate the site.

Awaba utilises bord and pillar methods for development and pillar extraction within narrow panels by continuous miners.

This method was developed and successfully used since 2007 in the Main South area and 3 North area.

Mining is ongoing in existing and historical workings areas of the Main South area in remaining areas of Stage 2.

Mining will similarly continue into the existing workings of the Revised Stage 3 area.

A proposed East B area includes both existing and historical workings areas and new mining areas.

The predicted maximum subsidence is assessed to be less than 200 millimetres, the upper limit used for assessment, although generally subsidence is within a range of 90-135mm.

Maximum subsidence measured to date is 119mm.

“Awaba Colliery also undertakes a very conservative risk-based approach, though it is also considering the highly unlikely worst case scenario of a ‘plug’ failure event (2000mm subsidence) in mining areas,” the company said.

“Key environmental aspects have been reviewed and assessed for potential impacts in each mining area within this environmental assessment for the project.”

Coal is crushed onsite at the Awaba Colliery Coal Preparation Plant.

The colliery is a well established underground mine with adequate support infrastructure and a well defined resource boundary so minimal land preparation is needed for exploration or construction purposes.

Centennial is proposing minor changes in the surface facilities area to expand capacity of the site’s pollution control dam, which will be undertaken in a previously disturbed area.

Infrastructure and support facilities at Awaba Colliery generally include infrastructure for mine access and ventilation, coal handling, preparation and transport, workshop and administration, water management and pollution control.

The aim of the water management system is to divert clean water away from areas of potential “dirty” water, such as coal stockpiles and some hardstand areas.

Dirty water is pumped from the surface into the underground where it is filtered through goaf areas before being discharged through a number of existing licensed discharge points or the 10 South Bore into the Eraring Energy Ash dam.