Acid Sulfate Soils
Acid sulfate soil investigations and management plans to support compliant development in NSW coastal risk areas.
Why Acid Sulfate Soil Management Matters
Unmanaged disturbance of acid sulfate soils can lead to:
Acidification of groundwater and waterways
Corrosion of concrete, steel, and building foundations
Toxic effects on aquatic life and surrounding ecosystems
Mobilisation of heavy metals and contaminants
Non-compliance with NSW planning and environmental laws
Proper identification, risk assessment, and soil treatment strategies are essential — and often required by councils, SEPP (Coastal Management), and the NSW Acid Sulfate Soils Manual.
Our Acid Sulfate Soil Services
At Confluence Environmental, we provide comprehensive, site-specific acid sulfate soil solutions for developments in mapped ASS risk areas (Class 1–5). Our services include:
Preliminary ASS Risk Assessment
Review of Acid Sulfate Soil Risk Maps (NSW SEPP Coastal Management 2018)
Desktop screening of Class 1, 2, 3, 4, and 5 areas
Advice on development triggers (e.g. excavation depth, groundwater interference)Soil Sampling & Laboratory Analysis
Field sampling in accordance with NSW ASS Guidelines
Chromium Suite analysis: Field pH, pH(oxidised), TAA, ANC, Net Acidity, SCR
Laboratory testing via NATA-accredited facilities
Identification of Actual ASS (AASS) and Potential ASS (PASS)
Acid Sulfate Soil Management Plans (ASSMP)
Risk mitigation strategies for excavation, dewatering, or piling
Lime dosing and soil treatment calculations
Dewatering and water quality protection measures
Temporary stockpile and reuse management
Monitoring, documentation, and verification methods
Written to support DA approval and construction compliance
Implementation Support
Advice during excavation, remediation, and validation
Site inspections, pH testing, and field verification
Final compliance reporting for council or EPA submission
Who We Work With
We support a wide range of clients working in or near mapped acid sulfate soil risk areas:
Property developers and subdivision planners
Civil contractors and builders
Local councils and infrastructure agencies
Environmental consultants and town planners
Coastal and estuarine project stakeholders
Whether you’re preparing a DA or managing excavation works, we help ensure your project is compliant, low-risk, and environmentally responsible.
Why Choose Confluence Environmental?
NSW-specific expertise in acid sulfate soil regulations
Detailed ASSMPs aligned with the NSW Acid Sulfate Soils Manual
Accurate, science-led assessment with NATA-accredited testing
Fast, responsive turnaround to meet planning timelines
Trusted by developers, contractors, and councils across NSW
We make it easier to manage ASS risks — and get your project approved.
Service Areas
We assess and manage acid sulfate soil risk across:
Central Coast
Greater Sydney
Newcastle & Lake Macquarie
Hunter Valley
NSW coastal floodplains and estuarine environments
Need expert advice?
Planning a project in a mapped acid sulfate soil risk area? We provide fixed-fee quotes, quick turnarounds, and tailored advice for your site and DA requirements.
Call 0493 042 642 or drop us an enquiry below to speak with a consultant today.
Frequently Asked Questions (FAQ) – Acid Sulfate Soils (ASS)
Q: What are acid sulfate soils?
Acid sulfate soils (ASS) are naturally occurring soils or sediments that contain iron sulfides, typically found in low-lying coastal and estuarine areas. When disturbed by excavation, drainage, or dewatering, these sulfides react with oxygen and produce sulfuric acid — leading to environmental harm, infrastructure corrosion, and water contamination.
Q: How do I know if my site is affected by acid sulfate soils?
Sites within mapped ASS risk areas (Class 1–5) under the NSW SEPP (Coastal Management) 2018 or local council mapping may be at risk. A preliminary acid sulfate soil investigation, including soil sampling and laboratory analysis (e.g. pH, TAA, ANC, Chromium Suite), can confirm the presence of Actual or Potential Acid Sulfate Soils and assess the level of risk.
Q: What are the risks of disturbing acid sulfate soils?
If disturbed without proper management, ASS can cause:
Acidification of soil and groundwater
Damage to concrete, steel, and building foundations
Release of heavy metals into the environment
Toxic impacts on aquatic ecosystems and vegetation
Non-compliance with planning or environmental approvals
Q: How are acid sulfate soils managed on construction or development sites?
Management depends on the site’s risk level, soil type, and proposed works. Common strategies include:
Avoiding or minimising excavation in high-risk areas
Lime dosing or neutralisation of acidic or reactive soils
Controlled dewatering and containment of runoff
Stockpile and spoil handling procedures
Preparation of an Acid Sulfate Soil Management Plan (ASSMP) to guide excavation, monitoring, and validation
Q: What regulations apply to acid sulfate soil management in NSW?
In NSW, acid sulfate soil management is governed by:
The SEPP (Coastal Management) 2018 and council-specific planning instruments
The NSW Acid Sulfate Soils Manual (1998)
The Protection of the Environment Operations Act 1997 (POEO Act)
Environmental assessment requirements under the EP&A Act for development applications
If your site is in a mapped risk area and involves excavation, dewatering, or filling, you’ll likely need an ASS investigation and management plan to support your DA or construction works.