When contaminated land is discovered on a property in Western Australia, the first question most owners, developers and businesses ask is: who is responsible?
The answer depends on the circumstances:
- Who caused the contamination
- When it occurred
- Who currently owns or occupies the site
Under WA regulations, responsibility typically sits with the person or entity that caused or contributed to the contamination. Where the original polluter cannot be identified or no longer exists, responsibility may shift to the current owner, occupier or the person in management or control of the land.
This article provides general guidance on contaminated land duties in WA, the regulatory framework, and what stakeholders should do when contamination is suspected.
What Is Contaminated Land in Western Australia?
Under the Contaminated Sites Act 2003, contaminated land is land, surface water or groundwater where chemicals or wastes are present at levels that pose, or may pose, a risk to human health or environmental values. The definition covers both historical and current contamination and applies whether the contamination originates on or migrates from the site in question.
DWER classifies contaminated sites based on risks to human health and the environment. Once a site is reported, it is assessed and assigned a classification such as:
- Possibly contaminated: investigation required
- Contaminated: remediation required
- Contaminated: restricted use
- Remediated for restricted use
- Not contaminated: unrestricted use
Contamination can exist across multiple environmental components, including soil, fill material, groundwater, surface water, soil vapour and building materials. Common contaminants encountered in WA include:
- Hydrocarbons (petroleum, diesel, fuel oils)
- Heavy metals (lead, arsenic, cadmium)
- PFAS (per- and polyfluoroalkyl substances)
- Chlorinated solvents and degreasers
- Nutrients (nitrogen, phosphorus)
- Asbestos
- Acid sulfate soils
How Land Becomes Contaminated
Many contaminated sites in WA arise from historical activities that pre-date current environmental standards. Things that were once considered routine (like storing fuel underground, disposing of chemicals on-site or filling low-lying ground with unknown material) are now recognised as common sources of contamination.
Typical activities that can lead to contaminated land include:
- Fuel storage and service stations
- Mechanical workshops and vehicle depots
- Landfills and waste disposal areas
- Industrial processing and manufacturing
- Dry cleaning operations
- Agricultural chemical storage and application
- Former gasworks
- Rail yards, port facilities and defence sites
Contamination enters the ground and water through leaks, spills, dumping, burial of waste materials, use of uncontrolled fill and disturbance of acid sulfate soils. In Perth’s sandy soils, contaminants can infiltrate rapidly to shallow groundwater, creating plumes that migrate off-site and affect neighbouring properties or environmental receptors.
Who Is Responsible When Contaminated Land Is Discovered?
Responsibility for contaminated land is generally linked to the person or entity that caused the contamination. However, current owners and occupiers also carry obligations once contamination is discovered or becomes known.
Regulations dictate the following order of responsibility:
- The person who caused or contributed to the contamination (the polluter)
- The person in control of the contaminating activity
- The current owner of the site
- The current occupier or person in management or control of the land
Where the original polluter cannot be identified, is insolvent, or no longer exists, responsibility may move to the current owner or those who benefit from or propose changes to the land use. For orphan sites, the State Government may ultimately assume responsibility. Regulators will ultimately determine legal responsibility.
Historical vs New Contaminated Land Duties
The distinction between historical contamination and contamination from current activities is important when determining responsibility.
For contamination that occurred before the Contaminated Sites Act 2003 commenced, liability for the original polluter is limited to circumstances where the contaminating act was carried out without lawful authority. Many historical practices, though now understood to be harmful, were lawful at the time, complicating the assignment of responsibility.
For contamination arising after the Act commenced, a stricter standard applies. Any person who causes or contributes to contamination may be held responsible.
Regardless of when contamination occurred, once it is identified there are clear obligations to manage risks to human health and the environment.
How Responsibility Affects Owners, Occupiers, Developers and Businesses
Contaminated land duties have practical, financial and timing implications for every stakeholder involved with a site.
- Property owners may face disclosure obligations, investigation and remediation costs and impacts on property valuation. Failure to disclose the required information can lead to penalties of up to $125,000.
- Occupiers or tenants have obligations not to worsen contamination and must cooperate with investigations or remediation activities undertaken on-site.
- Developers in Perth metro must consider contamination status before proceeding with land redevelopment projects. Where land use changes from industrial to residential or another sensitive use, stricter remediation standards apply. Detailed site investigations can prevent significant project delays.
- Operating businesses may need to upgrade storage and spill control measures, implement groundwater or soil vapour monitoring and document management measures to demonstrate compliance.
Responsibility can also influence financing, approvals and settlement timeframes. Asbestos discovery, for example, can cause significant project delays and require specialist management before construction can resume.
West Soil & Water regularly assists clients to understand these implications early in project planning, helping to identify potential issues prior to purchase, development application or construction commencement.
Why Identifying the Source and Extent of Contamination Matters
Proper identification of the source, nature and extent of contamination is central to determining responsibility and choosing appropriate management or remediation options. Without clear evidence, it is difficult for regulators to decide who is responsible or what level of response is required.
Clear delineation of contamination:
- Helps regulators decide who is responsible under legislation and regulation
- Informs whether remediation, containment or ongoing management is the appropriate response
- Reduces uncertainty for buyers, lenders and project partners
- Supports safe construction, earthworks and asset design
- Clarifies whether contamination is migrating off-site through groundwater or soil vapour pathways
We conduct thorough investigations that save time and money in redevelopment by resolving unknowns early rather than mid-project. These models use soil and groundwater data to identify the sources, pathways and receptors relevant to your site, providing a foundation for any further assessment or remediation.
What to Do if You Suspect or Discover Contaminated Land
If you are a property owner, developer or manager and you encounter or suspect contamination on your site, acting promptly and methodically prepares you for the best possible outcome. Avoid making assumptions about what is or is not a problem and seek expert advice as early as possible.
Immediate actions to consider:
- Cease or control activities that may be causing or spreading contamination
- Implement basic safety measures to protect occupants, the environment and the public
- Collate existing information, including historic reports, site plans, previous uses or any prior assessment
- Seek professional environmental advice from a West Soil & Water consultant
- Engage with regulators as required
Avoid moving or disposing of potentially contaminated soil or groundwater without advice. Uncontrolled removal of contaminated material can create new contaminated sites at the receiving location or lead to additional liability.
How West Soil & Water Supports Clients with Contaminated Sites
At West Soil & Water, our consultants understand WA’s regulatory and environmental landscapes like the backs of their hands. They use that knowledge to build contextually relevant, site-specific contamination investigations for properties of all descriptions.
The typical stages of our assessments (conducted across WA) are:
- Desktop and Preliminary Site Investigation (PSI): a PSI involves reviewing the historical land use to identify potential contamination sources, combined with a site walkover and initial sampling where warranted.
- Detailed Site Investigation (DSI): a DSI includes soil and groundwater sampling to evaluate contamination levels, along with vapour testing where volatile contaminants may be present.
- Remediation or management planning: where required, development of a written document setting out objectives, methods and validation criteria. Sites with contamination can be remediated through excavation, treatment or containment based on risk assessments.
All assessments are supported with high-quality technical advice and regulator ready reporting.
Speak with an Environmental Consultant Today
Whether you are planning redevelopment or responding to an unexpected contamination discovery, early and informed assessment reduces risks, manages liability and keeps your project moving.
West Soil & Water provides expert technical advice on contaminated land duties, suspected contaminated sites and proposed developments in Perth and across regional Western Australia.
To learn more about land contamination guidelines or arrange a site assessment, get in touch.