THE West Wallsend underground coalmine near Killingworth would create up to 2.5 metres of mine subsidence above its new workings, plans on display with the state government indicate.
The plans also show mine operator Xstrata has agreed to give up as much as 4.4 million tonnes of coal to protect Aboriginal archaeological sites and artefacts found in a three-week search.
Some of these important areas include "crying trees" - which have marks indicating Aboriginal graves in the area - and "grinding grooves" where tools were sharpened on rocks.
Some of the new longwall panels will run underneath sections of the Great North Walk bush track, which may also need remediation after mining.
West Wallsend has operated since 1969 but Xstrata has lodged a new mining plan in line with a state government call for NSW coalmines to consolidate their various approvals into "one updated and contemporary approval".
The mine operates under bush that was formerly the Awaba and Heaton state forests but is now part of the Sugarloaf State Conservation Area.
An environmental assessment by Umwelt (Australia) notes that parts of the mining area, especially longwall panels 39 to 48, were underneath steep slopes, meaning the potential for "steep slope soil failure" would be high, although it could be reduced to medium because of the high density of vegetation in the mining area.
Xstrata plans to mine as much as 5.5 million tonnes a year over the next 10 to 12 years, for an estimated total of 36 million tonnes of "run of mine" or unwashed coal.
Xstrata says continued operation will support a workforce equal to 390 full-time employees.
It says the mine contributed $29.5 million in state coal royalties during 2008 and 2009, and would add about $448 million a year to the regional economy.
The plans are on display until August 28.
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