Comprehensive Acid Sulfate Soil Assessments and Investigations - Newcastle

Acid Sulfate Soils (ASS) — sometimes written as acid sulphate soils — are a common trigger for Newcastle City Council and surrounding coastal councils. Low-lying areas across Newcastle, Lake Macquarie, and the Hunter estuaries are mapped as Class 1–5 ASS risk zones. If left unmanaged, they can stall a Development Application (DA), complicate bulk earthworks, and increase project costs.

Confluence Environmental is a Newcastle-based consultancy providing Preliminary Acid Sulfate Soil Investigations, desktop reviews, and site-based assessments for development projects across the Newcastle LGA. Our DA-ready soil reports are fast, practical, and prepared in line with NSW EPA guidance and local council requirements.

Newcastle Acid Sulfate Soil Assessment Services

Preliminary Investigation & Desktop Review

• Review of Newcastle City Council’s ASS mapping (Class 1–5).

• Section 10.7 Planning Certificate checks for ASS notations or contamination triggers.

• Historic land use review, aerial photography, hydrology, and elevation data relevant to the Hunter estuary and coastal alluvials.

• Identification of site-specific triggers for further field investigation.

Field Investigation & Soil Testing in Newcastle

• On-site walkover inspection by a Newcastle environmental scientist.

• Targeted boreholes/test pits at mapped or at-risk locations across the LGA.

• Field screening: pH (field pHF), pH after oxidation (pHFOX), electrical conductivity (EC).

• Groundwater checks where relevant to excavation depth.

• Laboratory analysis through a NATA-accredited facility:

  • SPOCAS suite (TAA, TPA, TSA, ANC).

  • CRS testing where applicable.

  • Acid Base Accounting (ABA/NAPP) for net acidity and lime demand.

Reporting & Risk Assessment

• Clear documentation of Newcastle site conditions and potential ASS sources.

• Identification of areas of environmental concern (AECs).

• Preliminary risk assessment of contaminant sources, pathways, and receptors.

• A concise conceptual site model (CSM) for the site.

• Recommendations on whether a management plan or further investigation (Stage 2) is required.

When Will Newcastle Council Ask for an ASS Assessment?

You may be required to submit an acid sulfate soil assessment if:

• Your site is mapped in Newcastle City Council’s Class 1–5 ASS layers.

• Works involve excavation below the water table, trenching, dewatering, or bulk earthworks in mapped zones.

• A DA information request or condition requires an Acid Sulfate Soil Management Plan (ASSMP).

Beyond Assessment – Management Plans & Dewatering

Where assessments confirm the presence of PASS or AASS, we also prepare:

• Acid Sulfate Soil Management Plans (ASSMPs): Construction-ready documents with excavation controls, lime treatment, monitoring, and verification procedures.

• Dewatering Management Plans: Treatment train design (settlement → neutralisation → polishing), discharge criteria, field monitoring, and NATA laboratory testing.

Learn more about Management Plans and Dewatering ➝

Why Choose Confluence Environmental in Newcastle?

• Local Newcastle-based consultants with direct experience in coastal ASS investigations.

• Trusted DA-ready reports that Newcastle City Council accepts without back-and-forth.

• End-to-end service: desktop reviews, preliminary investigations, soil testing, and management plans.

• Competitive pricing, clear scopes, and responsive turnaround.

📞 Call 0493 042 642 or request a fast quote for Acid Sulfate Soil Assessments, Investigations, and Soil Testing in Newcastle, Lake Macquarie, the Hunter Valley, and surrounding NSW regions.