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Proper contaminated land management is critical for development, compliance and liability. The first step in good management is a thorough contaminated land investigation.
This process starts with a Preliminary Site Investigation (PSI). If that indicates presence of contaminants, it should be followed by a Detailed Site Investigation (DSI) or Phase 2 Environmental Site Assessment. These are crucial in uncovering the information that protects site owners, developers and prospective buyers from costly surprises and uninformed decision making.
This article explains what DSIs are, why they are so important and how West Soil & Water can conduct one on your site.
When investigating contaminated land, there are two types of assessments you can complete:
Preliminary Site Investigation/Phase 1 Environmental Site Assessment
Detailed Site Investigation/Phase 2 Environmental Site Assessment
A DSI is a structured investigation carried out when contamination has already been confirmed through a PSI. It involves targeted sampling and analysis of soil, groundwater or surface water to determine:
The extent and severity of contamination.
The types of contaminants present (such as hydrocarbons, heavy metals or asbestos).
Potential risks to human health, the environment or site usability.
In Western Australia, DSIs need to be conducted in line with the Contaminated Sites Act 2003 and other frameworks established by the Department of Water and Environmental Regulation (DWER).
At West Soil & Water, our consultants will typically recommend or conduct a DSI when:
A PSI has indicated contamination but lacks sufficient detail about extent or risk.
The land has a history of industrial, agricultural or waste storage activity.
The site has been classified as potentially contaminated by DWER.
A lender, regulator or investor requires certainty about site suitability.
There is a regulatory obligation to confirm or monitor contamination levels.
As a general rule, if your PSI raises more questions than answers about contamination on site, a DSI is the logical next step.
Like other contamination risk assessments, DSIs can be conducted in many ways. A typical West Soil & Water investigation might include:
Intrusive investigations such as drilling or test pits.
Collection of soil, groundwater or surface water samples.
NATA-accredited laboratory analysis of contaminants against investigation levels.
Risk assessment to identify potential impacts on health, ecosystems or future land use.
Reporting and documentation that outlines findings, implications and potential remediation needs.
This process provides more than enough detail to develop effective remediation strategies and demonstrate compliance to regulators and stakeholders. Should you need, we are also able to assist with remediation services.
Conducting a DSI does have some upfront costs, but those costs are outweighed by:
Confidence in regulatory compliance: Ensure your obligations under the Contaminated Sites Act are met.
Informed decision-making: Reduce uncertainty in property transactions and development planning.
Better risk management: Identify liabilities early and get a basis for mitigation.
Improved roject efficiency: Minimise costly delays by clarifying risks upfront.
If your site needs a DSI, but you opt against it, you will come across these challanges:
Undiscovered contamination surfacing during construction, halting works and blowing out budgets.
Regulatory bodies imposing penalties or classification changes.
Financial institutions unwilling to support transactions.
Significantly higher long-term remediation costs.
At West Soil and Water, we design each contaminated site investigation to meet regulatory requirements and project goals. Our consultants have over a decade of experience working on sites across Western Australia, helping clients move from initial screening through to remediation planning.
Our PSIs and DSIs are set apart by:
Experienced consultants familiar with WA’s contaminated sites framework and unique environments.
Robust sampling and NATA-accredited analysis aligned with DWER guidelines.
Clear reporting that supports compliance, project planning and risk management.
It’s important to understand that a DSI is about more than just proving your compliance. It’s a safeguard against unforeseen costs, liabilities and project delays. If you have any concerns about contamination on your site, engaging us for a DSI is the most responsible step you can take.
To speak with us about contamination risks assessments or any other services, please contact our team.