Expert Acid Sulfate Soil Assessments and Investigations - Central Coast

Acid Sulfate Soils (ASS) — also written as acid sulphate soils — are a common trigger for Central Coast Council in low-lying and estuarine areas such as Tuggerah Lakes, Brisbane Water, Lake Munmorah, and coastal floodplains. If left unmanaged, they can stall a Development Application (DA), complicate bulk earthworks, and increase project costs.

Confluence Environmental is a local Central Coast consultancy providing Preliminary Acid Sulfate Soil Investigations, desktop reviews, and field-based soil assessments. Our reports are DA-ready, practical, and prepared in line with NSW EPA guidance and Central Coast Council requirements.

Central Coast Acid Sulfate Soil Assessment Services

Preliminary Investigation & Desktop Review

• Review of Central Coast Council’s acid sulfate soil risk mapping (Class 1–5).

• Section 10.7 Planning Certificate review for acid sulfate soil or contamination notations.

• Historical land use checks, aerial photography, hydrology, and elevation data across local floodplain areas.

• Identification of triggers for further field investigation.

Field Investigation & Soil Testing – Central Coast

• On-site site walkover and inspection by an experienced Central Coast environmental consultant.

• Targeted boreholes/test pits in mapped or at-risk areas.

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

• Groundwater checks where excavation is near or below the water table.

• Laboratory analysis through a NATA-accredited laboratory:

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

  • CRS testing where applicable.

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

Reporting & Risk Assessment

• Documentation of current Central Coast site conditions and ASS risk.

• Identification of areas of environmental concern (AECs).

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

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

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

When Will Central Coast Council Ask for an ASS Assessment?

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

• Your site is mapped in Central Coast Council’s Class 1–5 acid sulfate soil layers.

• Proposed works involve excavation below the water table, trenching, dewatering, or bulk earthworks in mapped areas.

• Council issues a DA information request or condition requiring an Acid Sulfate Soil Management Plan (ASSMP).

Beyond Assessment – Management Plans & Dewatering

Where investigations confirm the presence of PASS or AASS, Confluence Environmental also prepares:

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

• 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 on the Central Coast?

• Local Central Coast consultants with experience in ASS investigations for lakeside and estuarine developments.

• Trusted DA-ready reports that Central Coast Council accepts without delay.

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

• Competitive fees, clear scopes, and fast turnaround.

📞 Call 0493 042 642 or request a fast quote for Acid Sulfate Soil Assessments, Investigations, and Soil Testing on the Central Coast, Tuggerah Lakes, Lake Macquarie, and surrounding NSW regions.