Leading Acid Sulfate Soil Solutions Across NSW
Ready to move your Acid Sulfate Soil project forward with confidence?
At Confluence Environmental, we provide practical, science-led solutions across contaminated land, asbestos and hazardous materials, waste classification, acid sulfate soils, and occupational hygiene.
Complete the form below to request a tailored quote, book a consultation, or ask us a question about your project. We’ll respond within 24 hours with clear advice and next steps helping you stay compliant, reduce risk, and keep your development on track.
Our Services
At Confluence Environmental, we provide comprehensive, site-specific solutions for developments in mapped ASS risk zones (Class 1–5).
Preliminary Risk Assessment
Review of council and SEPP Coastal Management 2018 mapping
Desktop screening of Class 1–5 risk areas
Advice on development triggers such as excavation depth and groundwater interaction
Soil Sampling & Laboratory Analysis
Field sampling in accordance with NSW ASS Guidelines
Chromium Suite testing: field pH, oxidised pH, TAA, ANC, Net Acidity, SCR
Laboratory analysis through NATA-accredited facilities
Identification of Actual ASS (AASS) and Potential ASS (PASS)
ASS Management Plans (ASSMP)
Risk mitigation strategies for excavation, dewatering, and piling
Lime dosing and neutralisation calculations
Runoff and groundwater protection measures
Stockpile and spoil management procedures
Ongoing monitoring, documentation, and compliance verification
Implementation Support
Practical advice during excavation, remediation, and validation
Site inspections, field pH testing, and verification sampling
Final reporting for submission to councils, certifiers, or the EPA
Who We Work With
We support a wide range of clients working in or near mapped coastal risk sediments, including:
Property developers and subdivision planners
Civil contractors and builders
Local councils and infrastructure agencies
Environmental consultants and planning professionals
Stakeholders managing projects in estuarine environments
Whether you’re preparing a DA or managing bulk earthworks, we help ensure projects remain compliant, low-risk, and environmentally responsible.
Why Choose Confluence Environmental?
NSW-specific expertise in ASS regulations and risk assessment
Detailed management plans aligned with the NSW ASS Manual
Accurate, science-led investigation with NATA-accredited testing
Fast turnaround to meet planning and construction timelines
Trusted by developers, contractors, and councils across NSW
We make it easier to manage reactive coastal soils and secure approvals with confidence.
Service Areas
We assess and manage ASS risk across:
Greater Sydney
Central Coast
Newcastle & Lake Macquarie
Hunter Valley
NSW coastal floodplains and estuarine environments
Frequently Asked Questions (FAQ)
Q: What are acid sulfate soils (ASS)?
They are naturally occurring coastal sediments containing iron sulfides. When disturbed by excavation, drainage, or dewatering, they react with oxygen to form sulfuric acid leading to environmental harm, water contamination, and infrastructure corrosion.
Q: How do I know if my site is affected?
Sites within mapped ASS risk areas (Class 1–5) under SEPP (Coastal Management) 2018 or council mapping may be at risk. A preliminary investigation with soil sampling and laboratory testing confirms the presence of Actual or Potential ASS.
Q: What are the risks of disturbing sulfidic soils?
If not managed, disturbance can cause:
Acidification of soil and groundwater
Damage to steel and concrete structures
Heavy metal release into the environment
Impacts on aquatic ecosystems and vegetation
Non-compliance with planning or EPA requirements
Q: How are these soils managed on construction sites?
Management depends on site conditions and proposed works. Typical strategies include:
Avoiding or minimising excavation in high-risk areas
Lime treatment and neutralisation of reactive soils
Controlled dewatering and runoff containment
Stockpile and spoil handling procedures
Preparation of an ASS Management Plan (ASSMP) for excavation, monitoring, and validation
Q: What regulations apply in NSW?
Management is governed by:
SEPP (Coastal Management) 2018 and council-specific planning controls
The NSW Acid Sulfate Soils Manual (1998)
Protection of the Environment Operations Act 1997 (POEO Act)
Environmental assessment requirements under the EP&A Act for DAs
If your site falls in a mapped risk zone and involves excavation, dewatering, or filling, an investigation and management plan is usually required.