What Councils Mean When They Say “Further Contamination Assessment May Be Required”
Prepared by Confluence Environmental environmental and contaminated land consultants supporting development approvals, remediation and validation projects across NSW.
If you’ve been involved in development approvals in NSW, you’ve almost certainly seen this phrase:
“Further contamination assessment may be required.”
It appears in development consent conditions, council referrals, planner correspondence and assessment reports. For many developers and project teams, it creates immediate uncertainty does this mean a full Detailed Site Investigation? Remediation? Delays? Additional cost?
In reality, this wording is usually a risk flag rather than a conclusion. Understanding what councils are actually signalling and how to respond can prevent unnecessary scope escalation and keep projects moving.
Where This Wording Comes From
The phrase “further contamination assessment may be required” typically arises during the planning assessment process and is used deliberately.
It is most commonly included in:
Development Application (DA) assessment reports
Conditions of consent
Council or referral agency comments
Planner or environmental officer correspondence
Councils use this wording when they believe there is potential contamination risk that has not yet been fully resolved, but where the available information is not sufficient to justify a definitive requirement at that stage.
It is intentionally flexible.
What Councils Are Really Flagging
In most cases, this wording reflects one or more of the following concerns:
Incomplete or Uncertain Site History
Historical information may indicate potentially contaminating activities, but documentation is limited or inconsistent.
Change to a More Sensitive Land Use
Proposals involving residential, childcare, education or similar uses often trigger closer scrutiny, even where contamination risk is considered low.
Inconclusive Preliminary Findings
A Preliminary Site Investigation (PSI) may have identified potential risks, data gaps or assumptions that require confirmation.
Lack of a Clear Conceptual Site Model
Where contamination pathways or exposure scenarios are not clearly articulated, councils may seek further clarification.
Reliance on Desktop Information Alone
In some cases, councils are signalling that intrusive investigation may be needed to support the conclusions reached.
Importantly, councils are not necessarily saying contamination exists they are saying confidence is not yet sufficient.
What “Further Assessment” Usually Means in Practice
Despite the wording, “further contamination assessment” does not usually mean jumping straight to a full Detailed Site Investigation.
In practice, it may involve:
A PSI addendum addressing specific gaps or assumptions
Targeted intrusive sampling in defined areas
Limited groundwater or soil vapour assessment
A hazardous materials survey for demolition or refurbishment works
Clarification or refinement of the Conceptual Site Model
The intent is typically to resolve a specific uncertainty, not to reopen the entire site assessment.
What It Usually Does Not Mean
This is where many projects lose time and money.
In most cases, this wording does not mean:
Automatic remediation is required
A full DSI is mandatory
The DA will be refused
Construction must be delayed indefinitely
Extensive sampling is expected regardless of risk
Over-interpreting the condition often results in unnecessary investigation scope and avoidable delays.
How to Respond Without Triggering Scope Creep
A measured, proportionate response is critical.
Effective responses typically involve:
Clarifying the specific concern being raised by council
Reviewing the existing PSI or environmental information against that concern
Proposing a targeted and staged assessment approach
Aligning any further work directly with the approval condition wording
Clearly documenting how the additional information resolves the identified risk
Councils generally respond well to clear logic and defensible reasoning, rather than large volumes of data.
Common Mistakes That Cause Delays
Projects often run into difficulty where:
Investigation scope is expanded without clear justification
Reports address issues not raised by council
The link between investigation findings and land use risk is unclear
The Conceptual Site Model is not explicitly updated
Recommendations are overly conservative or poorly explained
In many cases, the issue is not the presence of contamination, but how the information is framed and communicated.
A Typical NSW Scenario
A DA for a mixed-use development is supported by a PSI that identifies historical industrial use but no evidence of contamination based on limited sampling and site history review.
Council issues a condition stating that “further contamination assessment may be required prior to construction.”
Rather than proceeding directly to a full DSI, a targeted PSI addendum is prepared, including limited additional sampling focused on identified data gaps. The Conceptual Site Model is updated, and conclusions are clearly linked to the proposed land use.
Council accepts the additional information, and the project proceeds without further contamination conditions.
Key Takeaways for Developers and Project Teams
This wording is a risk flag, not a final determination
Councils are seeking confidence, not excessive investigation
Proportionate, targeted responses are usually sufficient
Clear logic and documentation matter more than sampling volume
Early technical advice helps avoid unnecessary escalation
Understanding what councils are actually asking for allows project teams to respond efficiently and keep approvals on track.
Getting the Right Advice Early
Conditions referencing “further contamination assessment” are common and manageable when approached correctly.
Confluence Environmental supports developers, planners and project teams by interpreting council conditions, designing proportionate investigation responses and delivering contaminated land assessments that align with regulatory expectations and project objectives.