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Warkworth was prosecuted by the Environment Protection Authority for breaching a condition of its Environmental Protection Licence that requires it to carry out its licensed activities in a competent manner.
The prosecution was in relation to an incident at the Warkworth mine when part of a sediment dam wall collapsed on January 5 2016 following several days of heavy rain.
Up to 4.4 megalitres of sediment laden water escaped into surrounding areas, including the nearby Wallaby Scrub Road reserve.
Warkworth had modified the dam to increase its capacity. However, neither the design nor the construction work was undertaken or overseen by an engineer, nor did Warkworth subject the completed works to an appropriate risk assessment or other quality assurance processes.
A section of the embankment wall collapsed when water levels reached the heightened embankment wall for the first time.
EPA north regional director Adam Gilligan said the dam wall failed due to a phenomenon known as “piping”, which occurs when circular shaped fissures form in the core of the dam wall due to excessive hydraulic pressure.
“It was estimated that at the time of the dam failure there was approximately 4.56ML of water in the dam,” Gilligan said.
“It is estimated that the discharge from the dam embankment took up to 18.5 hours.
“Ensuring that environment protection licence holders carry out their activities in a competent manner is an important part of a regulatory scheme that requires industries to take practical and reasonable steps to reduce their impact on the health of the community and environment.”
Gilligan said the court decision served as a warning to all operators to ensure they complied with their licensing requirements and carry out their activities in a competent manner.
Warkworth pleaded guilty to the offence.
In addition to the $50,000 penalty, which is payable to the Environmental Trust for general environmental purposes, the court ordered Warkworth to pay the prosecutor’s legal costs and to publish notices in the Singleton Argus and the Newcastle Herald detailing the conviction.
