The owner of Vales Point power station has been fined $30,000 for licence breaches after contaminated material, including asbestos, was discovered on site.
The NSW Environment Protection Authority (EPA) issued Sunset Power International Pty Ltd, which trades as Delta Electricity, two penalty notices for causing land pollution and unlawfully using the premises as a waste facility.
Adam Gilligan, the EPA's director regulatory operations, said on Monday that the material had been brought in as part of Delta's work to rehabilitate ponds in the power station's ash dam.
He said Delta advised the EPA in September, 2018, that the material, which was classified as general solid waste, had been accepted on site.
"The premises received waste that it was not licenced to accept, which resulted in contaminated fill being imported and spread on site," he said.
The EPA issued Delta with a clean-up notice to make the site safe and to assess and quantify the waste.
"The EPA has issued Delta a clean-up notice to remove various surface stockpiles of asbestos waste and we are continuing to liaise with them regarding options for dealing with the remainder of the waste in the long term," he said.
"Fortunately, on this occasion the waste was in an area that posed little risk to the community."
The EPA and Delta were both criticised by community and environment groups in early 2019 for not informing surrounding residents of the incident.
Mr Gilligan said Delta had since made improvements to its systems and procedures regarding accepting waste.
"It is important to be aware of the risks involved when accepting dirt and other materials like this," Mr Gilligan said.
"If the correct procedures are not in place - it can lead to large fines and damage to the environment."
