Cumnock has been following an interim mine plan since September last year while a drilling programme was completed to assess the long-term viability of the mine plan.
Xstrata, announced the decision in late January, ending 50 years of underground mining on the Cumnock lease, which operated from the late 1940s until 1991 as Liddell State Mine.
According to The Newcastle Herald, Construction, Forestry, Mining and Energy Union organiser Ian Murray said that the first 60 jobs would go in May, leaving about 85 workers to remove final coal up until December.
The CFMEU accepted the decision, agreeing the owners had everything possible to keep the mine viable.