The draft Approved Methods for the Modelling and Assessment of Air Pollutants in NSW represent more than a technical update. They have the potential to materially affect approvals strategy, timelines, cost and risk for projects across NSW.
From an approvals perspective, the proposed changes may play out in several practical ways:
Higher upfront effort and longer lead times
More prescriptive requirements for meteorological data, dispersion modelling and cumulative impact assessment may increase the front end effort required to get assessments “submission ready”, especially where:
- Five year meteorological review expectations apply
- Prognostic models (e.g. WRF) are used more frequently, depending on project context and risk
- Use of alternative models requires clear justification and early agreement with the regulator
Impact: Longer studies, higher study costs, and greater sensitivity to program delays, particularly for routine or lower risk projects.
Shift in modelling approach
The draft adds AERMOD to join CALPUFF as the primary regulatory models. While robust, this is a shift away from NSW’s historical approach.
Impact: Projects in dense urban areas, complex built environments, tunnels, ports or industrial precincts may face:
- A need to more carefully demonstrate model suitability for the local setting
- Additional justification effort
- More iteration with the regulator during method selection and review
More conservative outcomes for odour sensitive facilities
For waste, wastewater, composting, food and industrial facilities:
- Expanded “sensitive receptor” definitions
- More prescriptive use of legacy peak to mean ratios
- Use of a 1 OU contour to define affected populations
…may, in some cases, increase predicted impacts even where emissions or operations are unchanged, depending on site context and assumptions.
Impact:
- Larger modelled impact areas
- More stringent derived criteria
- Earlier or costlier mitigation triggers
- Higher risk of non approval for upgrades or expansions
Greater uncertainty where background levels are already high
Projects in growth areas or industrial regions with elevated background PM or NO₂ may struggle where:
- Background levels are becoming closer to criteria
- Even very small project increments risk triggering exceedances
- The interaction between SILs, DPTs and cumulative assessment is complex
Impact: Proponents may need to consider additional mitigation measures or offsets even where the incremental contribution is moderate, or in some cases the cumulative impact is within the criteria, depending on baseline conditions and the assessment framework.
Increased scrutiny of mitigation and “best practice”
The draft places stronger emphasis on:
- Early mitigation options analysis
- Demonstrating “maximum extent achievable” controls
- Justifying when further mitigation is not reasonably practicable
Impact: Expect more questions around:
- Cost effectiveness
- Feasibility thresholds
- Whether failure to meet DPTs means either redesign or potential refusal
Greater need for defensible, well documented strategy
Under the draft framework, defensibility will matter more than ever:
- Clear rationale for model choice
- Transparent assumptions around worst case scenarios
- Early engagement with regulators
Opportunity: Proponents who invest early in strategic scoping and regulator ready justification will be far better positioned than those relying on “standard” desktop studies.
Bottom line for your NSW project
The Draft Approved Methods increase the importance of early planning, proportionate risk assessment and strategic advice. While they aim to improve consistency, additional prescription may increase cost and complexity for some project types, depending on how the guidance is applied and refined.
Now is the right time for proponents to:
- Re examine approval pathways
- Stress test upcoming projects against the draft framework
- Engage early on modelling and odour strategy
Trinity has been closely monitoring the draft NSW EPA Approved Methods and is aligning our approach with the proposed direction. We can support your team with early strategic planning, risk-based scoping, negotiation with EPA, clear documentation and fit-for-purpose air quality and odour modelling to support timely engagement and well-prepared submissions.