Detailed in its application to the federal government, BMC aims to extend the open cut in a west to north-westerly direction, with work to start in February 2015.
Mining of the new project area, which encompasses 778 hectares, was flagged to start in 2017 and continue for 20 years.
A permanent 3.5km long Walker Creek diversion channel is part of the proposal.
Last year BMC applied to develop a new pit, Kemmis II, at the northern end of the mine.
HSE Contractors operates the mine which produced 1.31 million tonnes of metallurgical coal in each of the December and March quarters.
The federal applications are designed to meet the requirements of the Environment Protection and Biodiversity Conservation Act.