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.