Bloomfield Group sought the nine-month extension to allow mining to continue at Rix's Creek South while a separate development application, which would allow mining to continue until 2038, is assessed.

Fifty three public submissions were received in response to the public exhibition process. There were 28 objectors, 24 supporters and one comment.

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Objectors concerns included potential impacts on human health from noise and dust, an inadequate mine rehabilitation plan, greenhouse gas emissions and the decision to place the project on public exhibition during the NSW government caretaker period.

Those in support of the project cited the importance of providing continued employment to local workers, contractors and suppliers as well as the mine's contribution to the economy through salaries, wages, taxes and royalties.

As part of its statement of reasons for approving the modification, the commission noted "the application is in the public interest because the socio-economic contribution is likely to be greater than the continued environmental impacts of mining operations in an already active mine site with no change to the approved mining areas," the commission said.

Bloomfield argued that the extension was needed because the project provided work to 255 full time employees and 44 full time equivalent contractors.

It said the requested time extension would provide more certainty of employment for employees and contractors, certainty of supply coal to existing customers, and allow the it to continue fulfilling supply contract obligations.

It was noted during the assessment process that Singleton had grown significantly in the past 16 years. The town was now about five kilometres from the mine site compared to eight kilometres in 2003.

As part of its submission NSW Health said "there is no evidence of a threshold below which exposure to particulate matter is not associated with health effects."