The Environmental Protection Authority has backed the increase capacity of Australia’s only commercial repository for Class IV and V waste north-west of Kalgoorlie, with strict conditions.

Tellus Holdings proposed to increase the tonnage of its Sandy Ridge facility from 100,000 tonnes of waste a year to 280,000 tonnes.

Class IV waste covers contaminated soils and sludges while Class V includes intractable landfill under the state government’s classification.

The EPA today announced it has recommended the proposed increase tonnage for approval subject to strict conditions including for only Australian waste to be accepted at the Sandy Ridge facility.

Tellus operated the Sandy Ridge facility, about 240 kilometres north-west of Kalgoorlie or 75km north-east of Koolyanobbing, since 2021.

In its report, the EPA said it acknowledged the need for a suitable location for the permanent isolation of hazardous and intractable waste from environmental receptors.

However, the EPA said there had been been public interest in the origin of the material to be accepted at the facility.

“Under the original proposal it was anticipated that liquid waste, which requires immobilisation prior to disposal, would comprise the majority of waste received at the gate,” the report reads.

“Liquid waste generally requires immobilisation using bulky substrates, which means that the amount received at the gate would increase when disposed into the landfill.

“However, following the commencement of operations, the proponent is now seeking more operational flexibility to allow for increased solid waste receival during periods when there is less demand for liquid waste disposal”

EPA deputy chair Lee McIntosh said the public environmental review had assessed the proposal’s multiple potential impacts including flora, fauna and human health, after almost three years.

“The EPA recognises that disposal is the least preferred option for waste management, but we acknowledge there is also an ongoing need for a long-term permanent solution for hazardous and intractable wastes,” she said.

“The conditions the EPA has recommended relate to leachate monitoring and management, waste diversion, minimisation and stewardship, and a decommissioning plan to manage rehabilitation and remediation to ensure it is physically safe for members of the public and non-human biota in the long term.”

Ms McIntosh said potential impacts to human health from the increased transportation and handling of hazardous materials were low and subject to conditions that aimed to minimise risks.

“They would also require regulation through legislation administered by the Radiological Council and the Department of Energy, Mines, Industry Regulation and Safety, as part of the EPA’s use of provisions to consider other decision-making processes to mitigate impacts,” she said.

Tellus secured a 25-year approval to receive up to 100,000tpa of hazardous waste in 2021.