For developers, builders and planners told their council wants a landfill gas assessment for a planning permit in Victoria. Last reviewed June 2026.
You need a landfill gas risk assessment when you are proposing development on or near a current or former landfill, and your council requires it as a condition of the planning permit. The trigger is almost always the planning permit process: when a council (as the planning authority) identifies that a site sits within the buffer of a known or former landfill, it can ask for a landfill gas assessment before granting or finalising the permit. Whether one is actually required for your specific site depends on the landfill's characteristics, what you are building, and how EPA Victoria's landfill buffer guideline applies — not on a single fixed distance.
Landfill gas is produced as buried organic waste breaks down. It is approximately 50% methane (CH₄) and approximately 50% carbon dioxide (CO₂), plus trace gases such as hydrogen sulphide and volatile organic compounds. The concern is that this gas can migrate away from a landfill through the ground and reach a nearby development — which is why the assessment looks at sites both on and near a tip, not only on it.
There are two hazards. Methane is flammable and is explosive in air at concentrations between about 5% and 15% by volume, so risk arises if it accumulates in a confined or enclosed space — a basement, lift shaft, or void beneath a slab — and meets an ignition source. Both methane and carbon dioxide can also displace oxygen, creating an asphyxiation risk in confined spaces. Outdoors, the gas simply disperses; the real concern is gas entering enclosed or below-ground spaces, which is exactly why new buildings need to be checked before they are approved.
A landfill gas risk assessment is built on the Source–Pathway–Receptor (SPR) model, using the CIRIA C665 risk framework ("Assessing risks posed by hazardous ground gases to buildings"). For a real risk to exist, all three links have to be present:
If any link is genuinely absent — no credible source, no viable pathway, or no vulnerable receptor — the risk is correspondingly lower. The assessment's job is to establish, with evidence, which links exist for your particular site.
In practice, the requirement comes from two things working together: the planning permit process and EPA Victoria's landfill buffer guideline (2024). When you lodge a permit application for a site within the buffer of a known or former landfill, the council can require a landfill gas assessment so it can be satisfied the proposed use is suitable. Sensitive and below-ground uses raise the concern most — housing with basements, childcare, and aged care — because they put people in enclosed spaces for long periods.
The current framework is staged and risk-based. Depending on the landfill's characteristics (waste type, size, age) and the type of development you are proposing, the outcome falls into one of three tiers: (a) no further assessment, (b) a landfill gas risk assessment, or (c) a more involved environmental audit. There is no single points table you can run yourself — the factors are weighed for your specific site, which is why councils ask for a professional assessment rather than a self-declaration.
It helps to keep two different "buffer" ideas separate, because they are often confused. The headline figure you may have seen — a recommended buffer of up to 1,500 m (reducible to about 1,000 m with an appropriate assessment) — applies to siting a new landfill away from sensitive uses. It is not the distance that triggers an assessment when you develop near an existing tip. For developing near an existing or closed landfill, a screening distance of historically around 500 m has typically been the range within which landfill gas risk is considered. Treat that as a rule of thumb only: your council and the EPA guideline, applied to your specific site, determine whether you actually need an assessment — not a single hard number.
A landfill gas risk assessment is usually staged, so you only pay for the work your site warrants:
The work concludes with a report setting out the findings and, where needed, recommended gas protection measures. To check whether your property is anywhere near a known site before you commission anything, the free public tool is Victoria Unearthed (run by the Victorian Government), which brings together the landfill register, priority sites, and environmental audit locations. One important caveat: many old or closed tips are poorly documented or unregistered, so a clear map result is not a guarantee — a professional desktop review also checks historical aerial photographs and other records.
If your council has asked for a landfill gas assessment, Automated Environmental can scope it for your specific site and tell you which stage you genuinely need — request a free LFG RA quote or read more about our landfill gas risk assessments.
Because landfill gas — approximately 50% methane and approximately 50% carbon dioxide — can migrate through the ground from a current or former landfill and accumulate in enclosed or below-ground spaces. Methane is flammable between about 5% and 15% in air, and both gases can displace oxygen. A risk assessment establishes, using the Source–Pathway–Receptor model and the CIRIA C665 framework, whether that gas can actually reach people or buildings on your site, so the council can be satisfied the development is suitable.
Typically when you propose development — especially residential or other sensitive uses — on or near a current or former landfill, and the council requires a landfill gas assessment as a condition of the planning permit. The driver is the planning permit process combined with EPA Victoria's landfill buffer guideline (2024) applied to your site. Whether one is needed, and how detailed it must be, depends on the landfill's characteristics and what you are building, not on a single fixed distance.
A former or closed landfill can still generate gas for decades, so proximity to one can trigger an assessment just as a current landfill can. Gas generation is highest when a tip is young and falls over time — a roughly 30-year aftercare period is a common benchmark — but many old tips are poorly documented, so age alone does not rule out risk. A desktop study checks the registers, historical aerial photographs and geology to work out whether a closed landfill near you is a credible source.
The cost generally falls to the party seeking the planning permit — usually the developer, builder or landowner — because it is part of demonstrating the proposed development is suitable. There is no official published price. A straightforward desktop assessment for a clearly low-risk site sits at the lower end, while sites that need a walkover and months of ground gas monitoring cost more. Treat any figure as indicative and dependent on your site.
That depends on where your site lands in the staged, risk-based framework. Many sites need only a landfill gas risk assessment; higher-risk situations can require a Part 8.3 environmental audit under the Environment Protection Act 2017 (sometimes preceded by a Preliminary Risk Screen Assessment). The older "section 53V audit" term, under the repealed 1970 Act, is the legacy name people may still search for. An environmental audit is a larger, longer process, so it is worth confirming which path your site actually requires before committing.
Related reading: Landfill gas risk assessment vs environmental audit · How much does a landfill gas risk assessment cost? · Landfill buffer distances in Victoria
This article is general information, not legal or professional advice. EPA Victoria guidance should be read in full and professional advice obtained for your specific site and circumstances.
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