Preliminary Site Investigation
Summary
A Preliminary Site Investigation (PSI) is an environmental assessment undertaken to identify whether contamination is present or potentially present at a site. A PSI focuses on understanding site history, potential sources of contamination and environmental setting to determine whether further investigation is required.
PSIs are commonly prepared to support development applications, environmental due diligence and regulatory decision-making where land has a history of potentially contaminating activities.
Definition
A Preliminary Site Investigation is a non-intrusive or limited-intrusive assessment that evaluates potential contamination risk based on a review of historical land use, regulatory records, site inspection and available environmental information.
The primary purpose of a PSI is to determine whether the site is suitable for its intended use or whether a Detailed Site Investigation (DSI) is required.
Why Preliminary Site Investigations Matter
From a planning perspective, a PSI provides the initial evidence councils and regulators rely on to assess site suitability.
Without a PSI, contamination risks may be overlooked, leading to approval delays, additional conditions or refusal of development applications. A well-prepared PSI identifies issues early and allows an appropriate investigation pathway to be established.
From a project delivery perspective, PSIs help reduce uncertainty by flagging potential contamination, hazardous materials or groundwater risks before design or construction proceeds.
PSIs also support commercial decision-making by identifying environmental risks that may affect property value, development feasibility or transaction terms.
When a PSI Is Typically Required
A Preliminary Site Investigation is commonly required where:
Development or redevelopment is proposed
Land has a history of industrial, commercial or other potentially contaminating uses
A change to a more sensitive land use is planned
Environmental due diligence is required for a transaction
Planning authorities request confirmation of contamination risk
PSIs are typically the first step in a staged investigation process.
Typical Components of a PSI
While the scope varies depending on site history and regulatory expectations, a PSI commonly includes:
Review of historical aerial imagery and land use records
Assessment of regulatory databases and environmental notices
Site inspection and identification of potential contamination sources
Preliminary conceptual site model
Assessment of potential contaminants of concern
Recommendations regarding the need for further investigation
Limited intrusive sampling may be included in some cases.
Legislative and Regulatory Context
Preliminary Site Investigations are undertaken in accordance with environmental protection legislation, planning requirements and recognised industry guidance.
In New South Wales, PSIs are commonly relied upon by councils when assessing development applications and determining whether land is suitable for its proposed use. Similar regulatory frameworks apply across Australia.
Regulators expect PSIs to be proportionate, transparent and clearly linked to planning outcomes.
How We Can Help
Confluence Environmental undertakes Preliminary Site Investigations to support development, planning and transaction decisions.
Our services typically include:
Preparation of site-specific PSIs
Identification of contamination and hazardous materials risks
Clear recommendations regarding DSI or further assessment
Reporting aligned with council and regulator expectations
Integration of PSI findings into broader project strategies
We focus on delivering PSIs that are clear, defensible and approval-ready.
Related Terms and Concepts
Environmental Site Assessment
Contaminated Land
Detailed Site Investigation
Development Application
Environmental Due Diligence
Hazardous Materials Survey