In January 2019, AGL Macquarie self-reported that it had used the wrong sampling methodology of coal ash at its Bayswater and Liddell Power Stations after becoming aware it had not fully complied with sampling and analysis required under the EPA's Coal Ash Resource Recovery Order of 2014.

AGL Macquarie will pay $82,000 to the NSW Department of Planning, Industry and Environment to assist with the installation of air monitoring equipment in the Upper Hunter that will contribute to the statewide air quality monitoring network.

The company will also contribute $18,000 to the Singleton Shire Landcare Network for use towards the Col Fisher Park Weed Eradication Project.

AGL Macquarie will pay the EPA's investigation and legal costs of $37,356 and is required to undertake staff training, as well as place notices of the enforceable undertaking in local media.

NSW EPA director waste compliance Greg Sheehy said coal ash could contain high concentrations of heavy metals and other contaminants and needed to be handled in accordance with the Resource Recovery Orders to protect the community and the environment.

"AGL Macquarie self-reported that the sampling and analysis of their coal ash had not met the standards and frequency required under the EPA's Coal Ash Order of 2014," Sheehy said.

"While in this instance it was assessed that there was no human health risk or concerns for the ecology or aquatic ecosystems, it is vital that companies follow proper processes when dealing with coal ash."