Preliminary Site Investigations (PSI) – Expert Contamination Risk Reports for DA Approval, Land Use Planning, and Environmental Compliance

At Confluence Environmental, we deliver Preliminary Site Investigations (PSIs) that meet council, EPA, and planning requirements—while giving developers, planners, and property professionals the insight they need to avoid delays, manage environmental risk, and get projects approved.

Whether triggered by a Development Application (DA), planning proposal, rezoning, or land purchase, our PSIs uncover historical and environmental risks that could impact the viability, cost, or timing of your development.

What Is a Preliminary Site Investigation (PSI)?

A PSI—also referred to as a Phase 1 Environmental Site Assessment—is a desktop-based contamination assessment supported by site inspection and consultation. It is used to:

• Identify past and present land uses that may have caused contamination

• Evaluate environmental risks to soil, groundwater, surface water, air, and site structures

• Support compliance with the Contaminated Land Management Act 1997, SEPPs, and council planning controls

• Determine whether further investigation is required (e.g. a Detailed Site Investigation or DSI)

PSIs are essential for:

• DA approvals on land with commercial, industrial, or unknown history

• Rezoning, subdivision, or change to sensitive uses (e.g. childcare, schools, aged care)

• Due diligence prior to sale or purchase

• Site remediation planning and liability assessment

All assessments follow the NSW EPA Guidelines for Consultants Reporting on Contaminated Sites and the NEPM 2013 (Assessment of Site Contamination).

Why Conduct a PSI?

A PSI is not just a formality—it’s a critical step that:

• Protects project timelines by identifying contamination issues early

• Avoids costly redesign or remediation at later stages

• Builds confidence with councils, certifiers, investors, and communities

• Supports compliance with environmental regulations and planning law

• Safeguards health, safety, and environmental outcomes

• Maintains financial value by ensuring land suitability and minimising risk

Without a PSI, your DA may be delayed or refused. Worse, you may unknowingly inherit environmental liabilities.

Our Approach to Preliminary Site Investigations

Our consultants work with developers, councils, architects, and environmental lawyers to deliver tailored, decision-ready PSI reports. Every investigation includes:

1. Desktop Review and Data Analysis

We gather and interpret site-specific data to assess contamination risk:

• Historical aerial photos, zoning overlays, and land use records

• EPA public registers (Contaminated Land, Pollution Incident Notices, etc.)

• Past environmental reports, audits, and compliance notices

• UST registrations, WorkCover notifications, dangerous goods licensing

• Planning history, DA conditions, SEPP and LEP triggers

2. Site Walkover Inspection

We physically inspect the site to verify environmental and contamination risks:

• Soil staining, disturbed land, and illegal dumping

• Former chemical storage, tanks, or buried infrastructure

• Asbestos-containing material (ACM), demolition waste

• Site drainage, erosion, and topographical changes

• Proximity to sensitive land uses (e.g. watercourses, schools, residential areas)

3. Stakeholder Consultation

We liaise with key stakeholders to ensure completeness:

• Current and past owners or tenants

• Council planning or contaminated land officers

• NSW EPA (if required)

• DA consultants, planners, or certifiers

4. Preliminary Risk Assessment and Reporting

Every PSI report is:

• Structured for council and planning submission

• Clear and readable for both technical and non-technical users

• Aligned with planning, legal, and environmental obligations

Your report will include:

• Contaminants of Concern (CoCs) and likely sources

• A detailed Conceptual Site Model (CSM)

• An assessment of potential exposure pathways and receptors

• A conclusion on site suitability and next steps (e.g. DSI, RAP)

• Appendices with full desktop data and site findings

Who Needs a PSI?

We support:

• Developers and project managers preparing for DA lodgement

• Town planners and certifiers seeking expert input

• Buyers, solicitors, and financiers requiring due diligence

• Builders and civil contractors needing clearance before excavation

• Government and infrastructure teams requiring environmental reviews

Where We Work

We provide PSIs across New South Wales, including:

• Sydney, Blue Mountains, and Greater Western Sydney

• Newcastle, Lake Macquarie, and Hunter Valley

• Central Coast, Illawarra, and South Coast

• Mid North Coast and Northern Rivers

• Central, Southern, and Northern Tablelands

• Regional NSW on request

Why Choose Confluence Environmental?

• Proven experience in delivering regulator-aligned PSI reports

• Deep understanding of NSW environmental and planning frameworks

• Trusted by councils, developers, legal teams, and planners

• Clear, tailored reporting with practical recommendations

• Responsive communication and full support throughout the process