Preliminary Landfill Gas Monitoring Assessment

Raw Earth Environmental Pty Ltd was engaged by the North Sydney Council to conduct a Preliminary Surface Landfill Gas Monitoring Assessment at Forsyth Park, Montpelier St, Neutral Bay NSW 2089.

The EPA identified Forsyth Park as a priority for further investigation after an initial assessment suggested it may pose risks to human health and the environment. The EPA strongly recommended that North Sydney Council conduct its own due diligence investigation of the legacy landfill to determine the necessary level of environmental monitoring and management to safeguard human health and the environment. This investigation supported the EPA's recommendations.

Description of Services

The methane emission testing involved surface gas monitoring from 100 locations across Forsyth Park and within 250 m of potential receptors using an infrared gas monitor, as a first-pass screening process to determine whether the legacy landfill was presenting an obvious immediate risk to human health and/or the environment.

Whilst there are a number of landfill gases associated with legacy landfills, methane was considered the most appropriate, as it can cause asphyxiation and explosions in confined spaces and is an important greenhouse gas. Methane is also considered a useful tracer gas (e.g. detection of elevated methane can often indicate potential issues with other landfill gases).

For the purpose of this investigation, a five parts per million volume/volume (ppm v/v) acceptable concentration was adopted.

Specific Challenges

Legacy landfills that pre-date landfill legislation often lack appropriate engineering, environmental monitoring and/or management systems. Hazards associated with legacy landfills can include exposed waste, landfill gas emissions, odours, leachate migration, ground settlement/movement and subsurface fires. Addressing potential human health and environmental risks associated with these hazards can result in significant impacts on innocent parties and complex and expensive remediation and/or management works.

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