Steelmaker BlueScope could face a $150 million spend on new coal import facilities and annual costs of up to $100 million in the decade ahead amid signs the local coalfields that have supplied the Port Kembla steel mill for 80 years will shrink significantly after 2024.

BlueScope spent Friday studying the impact of a decision by NSW’s Independent Planning Commission (IPC) to block an extension of South32s Dendrobium coking coal mine out to 2048 because of concerns about the impact the mine would have on Sydney’s drinking water catchments.