Contaminated land is more common across Western Australia than many site owners and developers realise. Whether you are purchasing a former industrial property, rezoning land for residential use or planning construction on a brownfield site, understanding how contamination affects development is essential.
This guide covers everything you need to know from the legislative framework and site assessment process to remediation, approvals and due diligence.
Can You Build on Contaminated Land in Western Australia?
The short answer is: yes, contaminated land in Western Australia can often still be developed. However, development is only possible where contamination risks are properly understood, assessed and managed.
A contaminated site must be assessed under the Contaminated Sites Act 2003 (the CS Act) before any development proceeds. DWER will classify the site into one of seven categories that dictate building eligibility, ranging from “remediation required” through to “decontaminated.”
Developers are legally responsible for assessing and managing contaminated land before construction. The key factors that determine whether building can proceed include:
- The site classification assigned by DWER
- The proposed use of the land (residential, commercial, industrial or public open space)
- The type, extent and location of contaminants present in soil, groundwater and surface water
- Whether remediation or ongoing management is technically and financially feasible
- Compliance with state and national environment protection obligations
West Soil & Water supports owners and developers through every stage of this process, from initial investigation through to remediation planning and regulatory approvals across sites in Western Australia.
What Does ‘Contaminated Land’ Mean in Western Australia?
Contaminated land is defined as land, groundwater or surface water where hazardous substances are present at concentrations above background levels and pose, or may pose, a risk to human health, the environment or environmental values.
Common contaminants found on WA sites include:
- Petroleum hydrocarbons: improper fuel storage can lead to soil contamination, commonly around service stations and bulk fuel facilities.
- Heavy metals (lead, arsenic, chromium, cadmium): industrial processes often release heavy metals into the environment, particularly around workshops, metal yards and areas where fill materials of unknown origin have been imported.
- PFAS: per- and polyfluoroalkyl substances from firefighting foams, increasingly a focus of regulatory attention.
- Asbestos: asbestos can contaminate land if not properly handled during demolition or waste disposal.
- Solvents and VOCs: from dry cleaning, degreasing and chemicals manufacturing.
- Pesticides: from agricultural or timber treatment legacy uses.
It is worth noting that site contamination under the CS Act is distinct from general pollution or nuisance dealt with under other environment protection laws. Not every spill or discharge results in a classified contaminated site. Instead, classification is triggered by the persistence of hazardous substances and the risk they present to receptors.
Environmental Investigations, Soil Testing and Site Assessments
Where there is a risk or suspicion of contamination, environmental consultants are typically engaged to perform staged investigations, following a structured approach that satisfies both state and national requirements.
The typical investigation stages are:
- Preliminary Site Investigation (PSI): a desktop review and field assessment combining site history research, aerial imagery analysis, a physical walkover and identification of potential contaminant sources and receptors. The PSI establishes an initial conceptual site model showing how contamination may be present and how it could reach people or the environment. This document forms the basis for recommending further assessment if needed.
- Intrusive sampling: soil, groundwater and sometimes soil gas sampling to detect and measure contaminant concentrations. Laboratory analysis compares results against screening levels set out in the national environment protection measure and relevant Australian standard guidelines.
- Detailed Site Investigation (DSI): where contamination is confirmed, the DSI delineates the spatial extent and depth of contaminated soil and contaminated groundwater, assesses exposure risk and informs remediation options. This stage provides the data needed by an environmental professional to prepare remediation or management plans.
At West Soil & Water, all site testing and risk assessments are designed to National Environment Protection Measure (NEPM) and all relevant WA legislation.
Our investigations are the first step in understanding your site’s contamination profile, getting it classified by DWER and proceeding with development plans.
Remediation and Contamination Management Plans
Where contamination is confirmed and the site classified, development can often still proceed provided appropriate remediation or management controls are in place. There is an important distinction between these two approaches:
- Remediation: removing, treating or containing contamination to reduce risk to acceptable levels. Methods include excavation and offsite disposal, on-site treatment, groundwater pump-and-treat systems and installation of vapour barriers.
- Management: long-term controls that manage contamination risks where full removal is not feasible or required. This may involve capping, land use restrictions, monitoring and maintenance of barriers.
Where you opt for a management approach, a site management plan is required to guide ongoing monitoring and restrictions. Key components include:
- Procedures for handling, stockpiling and disposing of contaminated soil and materials during construction
- Controls on excavation depths and methods
- Groundwater monitoring schedules and reporting requirements
- Maintenance obligations for caps, barriers and infrastructure
- Restrictions on future land use (e.g. preventing sensitive use or groundwater extraction)
- Health and safety protocols for workers and the public
Our team will help you develop this plan, demonstrate your compliance and proceed with scheduled works.
How Land Contamination Affects Your Development and Land Use Options
The type, extent and location of contamination strongly influence what land use is acceptable on a given site. Land use planning must consider the environmental effects of contamination before approvals are granted.
Sensitive use categories attract the most stringent assessment and remediation requirements. Those include:
- Residential use
- Childcare centres and schools
- Aged care facilities
- Hospitals
- Community gardens
By contrast, commercial industrial land use can proceed with fewer controls.
Where remediation is required, strategies should correspond to the intended land use to ensure the site is made suitable for its planned purpose. Potential responses include:
- Vapour barriers and ventilation: volatile chemicals may require vapour barriers beneath slabs or specialised ventilation to prevent vapour intrusion into buildings.
- Groundwater restrictions: contaminated groundwater may prohibit bores for drinking water or irrigation and may affect stormwater design.
- Caps and covers: contaminated soil may be managed by capping, with restrictions on excavation or disturbance.
- Service trench design: utility conduits may need sealing to avoid acting as pathways for contaminant migration.
- Ongoing monitoring: some sites require environmental monitoring post-construction to verify that controls remain effective.
- Protected vegetation and environmental values: contamination may also affect protected vegetation, waterways or ecological receptors on or near the site.
Your Due Diligence Checklist: What to Do Before Buying or Developing Potentially Contaminated Land
If you are considering purchasing or developing land that may be affected by contamination, the following steps will help you be aware of risks and manage them before commitments are made:
- Engage West Soil & Water: commission a preliminary site investigation before settlement or early design, particularly for high-value or sensitive developments. Our environmental consultants can provide technical advice on contamination risks and regulatory requirements.
- Review site history: check past land use through aerial imagery, title searches, local councils records and any previous environmental reports. Understand whether the site or nearby land has been used for industrial, agricultural or waste disposal purposes.
- Search the DWER database: check whether the site is already classified or reported on the contaminated sites database. This is a straightforward step that can reveal known contamination risks early.
- Budget for remediation and management: factor potential remediation costs, timeframes and ongoing management obligations into feasibility studies and contract negotiations. Consider worst-case scenarios when preparing financial models.
- Understand reporting obligations: be aware that anyone who knows or suspects land contamination must report it to DWER. Disclosure obligations and reporting duties can affect transaction structure and timing.
- Negotiate accordingly: include contractual clauses related to contamination, such as indemnities, price adjustments or remediation responsibilities, in sale agreements.
Understanding the full picture before committing to a purchase protects both your investment and the environment.
How West Soil & Water Helps Manage Contaminated Sites in Western Australia
We are a WA-based, independent environmental consultancy specialising in contaminated land investigation, soil testing, groundwater assessment and acid sulfate soils.
Our core contaminated sites services include:
- Desktop assessments, preliminary and detailed site investigations and field assessment programs
- Soil and groundwater sampling with NATA-accredited laboratory analysis and data interpretation
- Human health and ecological risk assessment
- Preparation of remediation and management plans, including site management plans and contamination management plans
- Environmental monitoring, validation testing and compliance reporting
We support clients at each stage of their project’s lifecycle:
- Pre-purchase: due diligence advice, database searches and preliminary investigations to identify contamination risks before settlement.
- Investigation and classification: preparing technical reports to support DWER classification and address contamination under the CS Act.
- Planning and approvals: providing the technical documentation and guidance that planning authorities and local government require for development applications on contaminated land.
- Remediation and validation: oversight of remediation works, validation sampling and post-remediation reporting to confirm the site is suitable for its intended use.
Speak with an Environmental Consultant Today
We understand WA’s regulatory and environmental landscapes like the backs of our hands. That has allowed us to support businesses of all shapes and sizes in addressing contamination and demonstrating their compliance.
For further information or to discuss your site, contact West Soil & Water.