The leak in the Waratah rivulet, which lies in the Sydney catchment area and feeds the Woronora dam, follows a controversial decision by the NSW Department of Planning to allow Peabody to expand Metropolitan’s coking coal production by 1 million tonnes per annum.
"During a recent inspection, in accordance with Metropolitan Coal’s approved Water Management Plan, gas bubbling was detected in Pool H of the Waratah rivulet," Peabody spokesperson Jennifer Morgans told ILN.
"Metropolitan Coal has recovered gas samples and analysed the full gas spectrum and confirm that the gas contains methane and carbon dioxide. There is no impact to water quality.
"The Metropolitan Coal Environmental Approval notes that intermittent gas releases may occur. These are approved in this section of the rivulet. The Water Management Plan requires that in the event of gas bubbles appearing, weekly inspections will be initiated to record the nature and extent of gas and that appropriate government and community associations be advised.
"Metropolitan continues to fulfill these obligations and conduct weekly inspections."
The Sydney Catchment Authority (SCA)requested that Metropolitan Coal provide inspection data following the SCA’s site inspection.
"Metropolitan has complied with this request and will continue working with the SCA," Morgans said.
Deputy director-general of the NSW Department of Planning Richard Pearson recently defended the $70 million expansion of the Metropolitan longwall, which is located 1.5 kilometres from the reservoir, saying it had been rigorously examined before being approved.
“The merits of the proposed expansion of the Metropolitan mine were closely examined by the Department of Planning and the Planning Assessment Commission, which included specially appointed independent experts, before approval was given in 2009,” he said.
“Both the department and the PAC found the risk of the mine causing water loss from the dam was ‘very low’. Nevertheless, strict conditions were imposed on the company to ensure any water loss from the dam or its catchment due to mining would be ‘negligible’.”
The approval included a barrier to protect the Waratah rivulet, meaning 8.6Mt of coal with an estimated market value of $1-2 billion will not be mined.