Coastal Soil Risk Management for Developments from Port Stephens to Coffs Harbour

At Confluence Environmental, we specialise in Acid Sulfate Soil assessments and management plans across the Mid-Coast region—covering Port Stephens, Forster, Taree, Kempsey, Port Macquarie, Nambucca Heads, and Coffs Harbour. If your project involves coastal excavation or drainage near estuaries, floodplains, or wetlands, local councils may require a formal ASS assessment or Management Plan to support your Development Application (DA).

We help you navigate council requirements, assess soil risk, and manage obligations with confidence and speed.

Do I Need an ASS Report in the Mid-Coast Region?

If your site falls within Class 1–5 Acid Sulfate Soil risk zones (as shown in LEP planning maps), and you’re planning to disturb the ground, you will likely require:

• A desktop risk review

• On-site soil sampling and pH testing

• A full Acid Sulfate Soil Management Plan (ASSMP)

ASS assessments are typically triggered by:

• Excavation deeper than 1 metre (e.g. footings, trenches, tanks)

• Drainage works or lowering of the water table

• Dewatering, piling, or soil stockpiling

• Construction near lakes, estuaries, or floodplains

• Coastal developments in low-lying or reclaimed land

Our Acid Sulfate Soil Services

Desktop Risk Screening

• Review of council ASS Planning Maps and site levels (AHD)

• Summary of risk class, excavation triggers, and planning requirements

Soil Sampling & Chromium Suite Testing

• Field pH screening and pH-KCl comparison

• Laboratory analysis for TAA, SCr, ANC, Net Acidity

• Accredited testing aligned with the NSW Acid Sulfate Soil Manual (2014)

ASS Management Plans (ASSMP)

• Site-specific controls to prevent acid generation

• Lime dosing, soil separation, stockpile management

• Dewatering and treatment strategies, where required

• Plans tailored to match DA scope, LGA conditions, and EPA expectations

Council-Ready Reporting

• Clear, concise reports accepted by councils across the Mid-North Coast

• Can support DAs, CCs, construction certificates, and Part 4/5 approvals

Why Acid Sulfate Soils Are a Key Risk on the Mid-North Coast

Much of the Mid-Coast region lies on former swamplands, estuarine floodplains, and reclaimed coastal areas. When these soils—rich in iron sulfides—are disturbed and exposed to air, they can oxidise and form sulfuric acid. This damages:

• Concrete, steel, pipes, and building foundations

• Natural waterways and groundwater

• The regulatory standing of your development

We help reduce this risk early through targeted assessment and planning—so your project isn’t delayed or hit with costly compliance issues.

Our 5-Step ASS Process

1. Map Review & Risk Screening

2. On-site Soil Sampling and pH Testing

3. Lab Analysis – Chromium Suite

4. ASSMP Development & Council Consultation

5. Optional Validation Sampling & Reporting

Common Projects Requiring ASS Assessment

• Subdivisions near Wallis Lake, Tuncurry, Manning River, or Hastings River

• Roadworks and civil infrastructure along the Pacific Highway corridor

• Waterfront builds near Port Macquarie, Lake Cathie, and Nambucca

• Agricultural infrastructure (e.g. dams, bores, floodgates) in low-lying floodplain areas

• Coastal rezoning and infill development near Coffs Harbour and surrounding catchments

Why Choose Confluence Environmental

• Specialists in coastal soil science and ASS compliance

• Reports accepted by all Mid-Coast LGAs: Port Stephens, MidCoast, Kempsey, Port Macquarie-Hastings, Bellingen, Nambucca, Coffs Harbour

• Rapid mobilisation and clear reporting aligned to planning stages

• Trusted by planners, surveyors, engineers, and local builders

Areas We Service Along the Mid-North Coast

• Port Stephens, Tea Gardens, Hawks Nest, Forster–Tuncurry

• Taree, Wingham, Kempsey, Frederickton, Port Macquarie

• Lake Cathie, Wauchope, South West Rocks, Nambucca Heads

• Urunga, Bellingen, Coffs Harbour, Woolgoolga and surrounds