Acid Sulfate Soil Assessments – Central Coast Region

Unlock Development Potential While Managing Risk

At Confluence Environmental, we provide expert Acid Sulfate Soil (ASS) assessments and management plans across the Central Coast, helping developers, architects, and planners meet regulatory requirements, avoid costly delays, and progress land use changes with confidence.

Whether you're preparing a development application (DA), rezoning land, or undertaking excavation works in mapped risk areas, we support you through the entire ASS assessment process—from desktop investigations to field sampling, laboratory analysis, and Acid Sulfate Soil Management Plan (ASSMP) development.

Why Acid Sulfate Soil Matters on the Central Coast

Acid Sulfate Soils are naturally occurring sediments that, when disturbed, can release sulfuric acid and heavy metals—posing serious risks to the environment, infrastructure, and public health. Large parts of the Central Coast, including areas near Tuggerah Lakes, Wamberal, Terrigal Lagoon, Brisbane Water, and coastal lowlands, fall within high-risk ASS zones.

Disturbing these soils—through excavation, drainage, or groundwater interference—triggers mandatory investigations under NSW planning and environmental frameworks.

Do You Need an Acid Sulfate Soil Assessment?

Under the NSW State Environmental Planning Policy (SEPP) – Coastal Management, and many Central Coast Council LEP provisions, an ASS assessment is triggered if your proposed activity involves:

• Excavating or disturbing soil below 1 metre AHD in Class 1–5 ASS risk zones

• Constructing footings, trenches, or basements in mapped areas

• Lowering groundwater levels (e.g., dewatering)

• Installing infrastructure (e.g., stormwater, sewer, or water pipelines)

• Changing land use, particularly near wetlands, floodplains, or estuarine areas

If you're unsure, we offer rapid risk screening using the NSW Acid Sulfate Soil Risk Maps, planning overlays, and proposed excavation depths.

Our Acid Sulfate Soil Services in the Central Coast

1. Desktop Risk Screening

• Review of Council ASS risk classes and mapping

• Preliminary site review against DA scope

• Identification of potential disturbance triggers

2. Field Sampling & Laboratory Analysis

• Soil core logging and pHf/pHox field testing

• Chromium Suite analysis for sulfur content (TAA, ANC, net acidity)

• pHKCl and other stability indicators

• Sampling aligned with NSW ASS Guidelines

3. Acid Sulfate Soil Management Plans (ASSMPs)

• Clear, site-specific mitigation strategies

• Excavation staging and neutralisation methodology

• Dewatering management, spoil handling, liming rates

• Contractor-ready controls for environmental compliance

4. Regulatory and DA Support

• Reports accepted by Central Coast Council, DPIE, and certifiers

• Support during Section 4.15 assessments

• Expert response to Council RFIs or EPA concerns

Where We Work

We service all major ASS-prone areas of the Central Coast, including:

• Gosford, Woy Woy, and Brisbane Water catchments

• Tuggerah, Wyong, and Jilliby Creek areas

• Avoca, Wamberal, and Terrigal lagoons

• The Entrance, Bateau Bay, and lakefront lowlands

• Rural residential areas with proposed cut-and-fill earthworks

Why Choose Confluence Environmental

• Deep local experience in coastal ASS zones

• Fast turnaround for DAs and planning referrals

• Reports aligned with NSW Acid Sulfate Soil Manual (ASSMAC)

• On-the-ground sampling, analysis, and remediation planning

• Integrated support with other services like soil classification, contamination, and groundwater assessments