Ashton requested the modification to clarify its responsibilities as approved by the NSW Land and Environment Court in 2014.
A department spokesperson said the department agreed with Yancoal that some of the conditions in the existing approval were not clear as to their requirements, or when these requirements first need to be applied.
"The department has therefore recommended a number of minor changes to the conditions to clarity their intent to both Yancoal and the community," the spokesperson said.
"The IPC will now undertake its own consideration to determine whether this modification should go ahead."
The spokesperson said Yancoal had only requested to clarify the timing of when approval conditions were required to be met if the project was ever "taken up".
The modification request does not affect the court's requirement for Yancoal to purchase or otherwise reach agreement with Wendy Bowman, the owner of one of the key properties affected.
"The department received many objections from the community concerned that Yancoal was attempting to water down the court's requirements around the need to purchase Mrs Bowman's property," the spokesperson said.
"The department has been very respectful of these concerns and the Land and Environment Court's requirements. Consequently, it has not recommended a number of the changes proposed by Yancoal."