Please attribute to Spokesperson, Kelvin Walsh, Director City Development
“The 2018 data from GB11 relates to concentrations of benzene at depth at a location within the quarry pit outside of private properties. It is incorrect to infer there was a high risk to human health because of this reading.
“The high-risk rating from 2018 was a measure for chronic exposure over 30 years and does not reflect an immediate high risk on the day of the reading. Subsequent readings have decreased to acceptable levels.
“This is a best practice nationally adopted methodology for assessing gas concentrations at depth as they migrate through geology and present at surface level.
Brimbank City Council has implemented a comprehensive landfill gas monitoring program in compliance with recommendations of the 2013 environmental audit. The periodic monitoring is undertaken by industry-leading experts GHD Pty Ltd has included, where residents have given consent, monitoring gas levels in homes and within buildings.
At no time has methane been detected above the EPA criteria for an explosive hazard, which would immediately initiate contingency measures, including validation testing, disclosure to the EPA and emergency services allowing implementation of risk proportionate responses including evacuation such as what occurred in Cranbourne.
Brimbank City Council has also undertaken vapour monitoring from bores within and proximate to the waste mass. This monitoring considers the toxicity to human health by chronic exposure over a 30-year period. This is different from an immediate risk such as an explosion of flammable gas in a confined space.
The 2018 and 2019 monitoring data from GB11 does not translate to an immediate high risk to human health. The benzene concentrations detected in GB11 are not representative of concentrations within homes from buried waste.
All of the available monitoring data has been assessed by a team of industry-leading experts from GHD Pty Ltd and independently verified by an EPA appointed auditor, Mr. Ken Mival who is one of Victoria's most experienced auditors. The outcome of the risk assessments is that the risk to human health of residents and workers is low. Brimbank will continue its ongoing period monitoring program as part of the aftercare for the closed Sunshine Landfills.