A preliminary site investigation (PSI) is the first stage of assessing land for possible contamination. It reviews a site’s history and current condition to find out if past activities may have left contaminants in soil, groundwater or structures.
In NSW, councils often ask for a PSI with a development application when land may have hosted potentially contaminating activities. You may also see the service called a preliminary site assessment or simply a PSI.
Key takeaways
- A PSI is the first stage of a contaminated land assessment in NSW.
- It relies mainly on historical records and a site walkover, with sampling only where needed.
- Councils must consider a PSI for certain land, including sites proposed for housing or childcare.
- If the PSI identifies risk, the next step is usually a detailed site investigation (DSI).
What is a preliminary site investigation (PSI)?
A PSI identifies past and present land uses that could have contaminated a site and assesses the need for further work. The NSW EPA’s contaminated land reporting guidelines set out what a PSI report must cover. Consultants preparing preliminary and detailed site investigations follow these requirements so councils can review the findings. The same service is also called a preliminary site assessment or a Phase 1 environmental site assessment.
When is a preliminary site investigation required?
A PSI is usually required when a development application involves land that may be contaminated. Under section 4.6 of the Resilience and Hazards SEPP, councils must consider a preliminary investigation report for certain land before granting consent.
Common triggers include:
- Rezoning or changing land use to housing, childcare, schools, hospitals or recreation
- Developing land with a history of potentially contaminating activities
- Excavating or demolishing on former industrial or commercial land
- Buying, leasing or financing a property with an unknown history
- Developing land within an EPA-declared investigation area
The PSI process step by step
A preliminary site assessment generally moves through five stages.
| Stage | Purpose | Outcome |
|---|---|---|
| Desktop study | Identify past land uses and likely contamination sources | A list of areas and contaminants of potential concern |
| Site walkover | Check for staining, fill, tanks, odours or stressed vegetation | Field observations that confirm or rule out desktop findings |
| Conceptual site model | Link possible sources, exposure pathways and receptors | A clear picture of how contamination could affect people or the environment |
| Limited sampling (if needed) | Screen specific areas of concern | An early indication of contaminant presence |
| PSI report | Present findings against NSW EPA requirements | A recommendation on site suitability or further investigation |
Information reviewed during a PSI
The desktop study draws on several public and private records:
- Historical aerial photographs
- Land title records and past ownership
- Council section 10.7 planning certificates
- NSW EPA contaminated land and licence records
- Records of underground fuel tanks and dangerous goods storage
- Geology, soil and groundwater maps
- Previous environmental reports for the site
Does a preliminary site investigation include soil testing?
A PSI does not always include soil testing. Most PSIs rely on site history and a walkover inspection. A consultant may take limited samples when the history points to a specific concern, such as a former fuel tank. Full sampling programs belong to the detailed site investigation stage.
What happens after a preliminary site investigation?
The PSI report states whether the site suits its proposed use or needs further investigation. Where the risk is low, council can assess the development application using the PSI findings.
Where potential contamination is identified, a detailed site investigation (DSI) usually follows to measure contamination levels through sampling. Confirmed contamination then requires a remedial action plan. For earthworks, an unexpected finds protocol for excavation works guides crews if they uncover contamination on site.
Book a preliminary site investigation with EnviroX Consulting
EnviroX Consulting prepares preliminary site investigations for residential, commercial and infrastructure projects across Sydney and NSW. Reports follow NSW EPA guidelines and support development applications, land use changes and property due diligence. Where sampling is required, samples go to NATA-accredited laboratories for analysis.
Call 1300 599 996 or request a quote to discuss your site.
FAQs
What is a preliminary site investigation?
A preliminary site investigation is the first stage of a contaminated land assessment. It reviews site history and current conditions to identify contamination risk.
Is a preliminary site assessment the same as a PSI?
Yes. Preliminary site assessment is another name for a PSI. NSW EPA guidance uses the term preliminary site investigation.
When is a PSI required in NSW?
A PSI is usually required for development applications on land with potentially contaminating past uses. Councils also request one when land changes to housing, childcare or other sensitive uses.
How long does a preliminary site investigation take?
Timing depends on site size, site history and how quickly agencies supply records. EnviroX can confirm a timeframe once it reviews your site details.