Expert Acid Sulfate Soil Assessments and Investigations - Central Coast
Proven Track Record in Fast, Accurate and Reliable Acid Sulfate Soil Management Plans
Acid Sulfate Soils (ASS) are a common risk across the Central Coast region, particularly around Tuggerah Lakes, Brisbane Water, Lake Munmorah, and coastal floodplains. When disturbed by excavation, trenching, or dewatering, ASS can oxidise, producing acidic runoff, mobilising metals, and damaging concrete and steel.
Central Coast Council frequently requires an Acid Sulfate Soil Management Plan (ASSMP) as a DA condition where mapped Class 1–5 ASS areas are impacted.
Confluence Environmental prepares detailed, construction-ready ASSMPs for projects across the Central Coast, ensuring compliance with NSW EPA and council guidelines, while remaining practical for supervisors and contractors to use on site.
What’s Included in a Central Coast ASSMP?
Excavation & handling controls – staged excavation, segregation of PASS/AASS, immediate covering of exposed soils, lined and bunded stockpiles.
Treatment requirements – lime dosing rates derived from NATA laboratory results, onsite mixing methods, verification testing of treated material, and record sheets.
Dewatering management – treatment train design (settlement → neutralisation → polishing), field pH/EC/turbidity testing, discharge criteria, and hold points.
Supervision protocols – clear instructions for site supervisors and environmental monitors, including checklists, inspection points, and contingency measures.
Rainfall & runoff controls – containment, capture, diversion, and inspection hold points to prevent untreated discharges.
Waste & reuse pathways – advice on reuse options under EPA exemptions, or Waste Classification for off-site disposal.
Monitoring & reporting – regular field monitoring, verification sampling of treated soils, and concise close-out validation reports prepared for Central Coast Council.
When Will Central Coast Council Ask for an ASSMP?
An Acid Sulfate Soil Management Plan is usually required if:
Your site is mapped in Central Coast Council’s Class 1–5 ASS layers.
Proposed works involve excavation below the water table, trenching, bulk earthworks, or dewatering.
A DA information request or consent condition specifies the need for a site-specific ASSMP.
Related Services
Before a management plan can be prepared, councils often require a Stage 1 Acid Sulfate Soil Assessment or Preliminary Investigation. Confluence Environmental also provides:
Desktop reviews – council mapping, Section 10.7 Certificates, historical aerial photography.
Field investigations – boreholes, test pits, groundwater checks.
Soil testing – field pH, pHFOX, EC, and NATA-accredited analysis (SPOCAS, CRS, ABA/NAPP).
Risk assessments – identifying PASS/AASS zones and informing lime treatment rates.
Learn more about Central Coast Acid Sulfate Soil Assessments ➝
Why Choose Confluence Environmental on the Central Coast?
Local Central Coast consultants with extensive experience preparing ASSMPs accepted by Central Coast Council.
Verification testing, supervision guidance, and practical controls included in every management plan.
Plans written to be usable in the field by contractors, supervisors, and engineers.
End-to-end service: preliminary investigation → testing → management plan → verification and reporting.
Competitive pricing, transparent scopes, and responsive turnaround to meet DA deadlines.
📞 Call 0493 042 642 or request a fast quote for a Central Coast Acid Sulfate Soil Management Plan (ASSMP) tailored to your development.
Why choose Confluence Environmental for Acid Sulfate Soils on the Central Coast?
Need an Acid Sulfate Soil Management Plan?
Central-Coast based environmental scientists delivering Acid Sulfate Soil Management Plans, Verification Testing and Supervision. We make sure you’re DA-ready and cost-effective.
ASSMP for excavation, stockpiles & dewatering
Waste Classification, ENM/VENM & reuse pathways
Salinity/aggressivity inputs for designers
Call 0493 042 642 or Request a Fast Quote today.
Frequently Asked Questions
What are Acid Sulfate Soils and why do they matter?
Acid Sulfate Soils (ASS) are coastal and estuarine soils containing naturally occurring iron sulfides. When exposed to oxygen during excavation, trenching, or dewatering, these sulfides can generate sulfuric acid. This acid can corrode concrete and steel, mobilise heavy metals, damage aquatic ecosystems, and create compliance risks for development projects. Because of these risks, Central Coast Council regularly imposes DA conditions requiring Acid Sulfate Soil assessments and management plans.
When do I need an Acid Sulfate Soil Assessment on the Central Coast?
You will usually need an Acid Sulfate Soil Assessment if your site is:
Mapped within Central Coast Council’s Class 1–5 ASS risk areas (commonly around Tuggerah Lakes, Brisbane Water, Lake Munmorah, and low-lying coastal floodplains).
Involving excavation below the water table, trenching, bulk earthworks, or dewatering.
Subject to a DA information request or consent condition requiring a Preliminary Investigation or an Acid Sulfate Soil Management Plan (ASSMP).
Do I also need a Management Plan (ASSMP)?
If investigations confirm the presence of PASS (Potential Acid Sulfate Soils) or AASS (Actual Acid Sulfate Soils), councils typically require an ASSMP. This plan sets out the excavation and handling controls, lime treatment protocols, verification testing, dewatering management, and supervision requirements that contractors must follow during construction.
How fast can you deliver, and what areas do you service?
We align our turnaround times with DA and construction program requirements, often within standard council submission timeframes. Confluence Environmental services the Central Coast, Tuggerah Lakes, Brisbane Water, Lake Munmorah, Lake Macquarie, and surrounding NSW regions. Ask us about current availability for site inspections and reporting.