The ASX-listed company said the British Columbia complex had 338 million tonnes of open-cut coal resource, 106.9Mt indicated and 230.9Mt inferred.
Atrum last reported JORC resources of 159Mt late last year – 57Mt indicated and 102Mt inferred.
Officials said more than 80% of 85.3Mt occurred at 0-150 meters depth, and 96% of the resource could be found to depths of 200m.
“The resource upgrade includes the newly acquired coal lease applications contiguous with Groundhog [that was announced last month];” the company said, noting that its drilling program results were not part of that.
“The company is currently updating the resource model at Groundhog to include the 1012 drilling program. This has also been expanded to include the newly acquired lease applications and a revision to global coal resources is expected by March 2013.”
The company may also further extend the coal measures in a search for additional resources.
By the end of this month, Atrum is expecting a preliminary washed clean coal data report to include ash chemistry as well as sulphur content calorific value, volatile matter and fixed carbon.
Previous testing showed the potential for a 65% yield with low impurities (less than 10% ash, low-volatile matter, a fixed carbon content in excess of 85% and calorific value ranging from 7500Kcal to 8000Kcal)
“With a major resource upgrade still to come over the next few months, the coal endowment at Groundhog is shaping up to be significantly larger than first thought, potentially the largest of its kind,” chief executive officer Lyle Hobbs said.
Atrum’s coal resources at Groundhog are of anthracite to semi-anthracite rank, and the company feels it will yield met coal for a range of applications in steel and ferro-alloy.
Groundhog is close to mining infrastructure including power, water, rail and port facilities.
A rail line 30km south of the site continues to the dedicated coal terminals at the deepsea ports of Prince Rupert and Port Metro Vancouver.
Just before the close of the year, Atrum announced its purchase of a substantial coal licence package immediately adjacent to Groundhog, known as the Panstone Applications.
The acquisition was made for $C400,000 ($US402,000) and the issue of 750,000 fully paid ordinary shares.
The acquisition includes six coal licence applications covering 8343 hectares and associated historical exploration data.
This brings Atrum’s holdings in the Groundhog coalfield to 22,815ha.
The licence packages have been historically drilled, mapped, surface trenched and channel sampled.