Acid Sulfate Soil Management Plan (ASSMP)
Summary
An Acid Sulfate Soil Management Plan (ASSMP) is a site-specific document that sets out how acid sulfate soils will be managed during development, earthworks or remediation activities. The purpose of an ASSMP is to prevent or minimise acid generation, protect soil and water quality, and ensure compliance with planning and environmental approval conditions.
ASSMPs are commonly required for projects involving excavation, dewatering or ground disturbance in areas where acid sulfate soils are known or suspected to be present. They form a key part of environmental risk management for construction and redevelopment projects in Australia.
Definition
An Acid Sulfate Soil Management Plan is a technical management document that identifies acid sulfate soil risks at a site and defines the control measures, treatment methods, monitoring requirements and contingency actions needed to manage those risks during site works.
ASSMPs are typically informed by acid sulfate soil investigations and laboratory testing and are prepared in accordance with relevant state guidelines and approval conditions.
Why Acid Sulfate Soil Management Plans Matter
From a practical delivery and compliance perspective, an ASSMP provides the framework that allows works to proceed while managing environmental risk.
Where acid sulfate soils are disturbed without appropriate controls, sulphide oxidation can result in acidification of soil and groundwater, mobilisation of metals and off-site impacts to waterways and sensitive environments. An ASSMP sets out how these risks will be avoided or mitigated through planning, sequencing and treatment measures.
ASSMPs also provide certainty for contractors and project teams by clearly defining responsibilities, trigger levels, monitoring requirements and response actions. This reduces the likelihood of reactive decision-making on site and helps prevent delays, stop-work directions or regulatory intervention.
For planning authorities and regulators, an ASSMP demonstrates that acid sulfate soil risks have been properly considered and that appropriate management measures will be implemented during construction or remediation.
When an ASSMP Is Typically Required
An Acid Sulfate Soil Management Plan is commonly required where:
Acid sulfate soils have been identified or are likely to be present based on site investigations or ASS risk mapping
Excavation, dewatering or drainage works will disturb soils below the groundwater table
Bulk earthworks or changes to groundwater conditions may expose sulfidic materials
Development consent or infrastructure approvals include conditions requiring ASS management
Redevelopment is proposed on coastal, estuarine or floodplain land with known ASS risk
In many cases, an ASSMP is required before construction or earthworks can commence.
Typical Contents of an ASSMP
While the level of detail varies depending on site conditions and regulatory requirements, an ASSMP commonly includes:
A summary of site conditions and ASS investigation findings
Identification of ASS risk areas and materials
Earthworks and soil handling procedures
Treatment and neutralisation measures where required
Dewatering and groundwater management controls
Monitoring requirements, including soil and water quality
Trigger levels, corrective actions and contingency measures
Validation and reporting requirements
Legislative and Regulatory Context
ASSMPs are prepared in accordance with state-specific planning and environmental frameworks.
In New South Wales, ASSMPs are commonly required under development consent conditions and are informed by EPA guidance, ASSMAC principles and contaminated land management frameworks. Other states, including Queensland and Western Australia, have formal ASS guidelines that specify when management plans are required and what they must address.
Regulatory expectations vary by jurisdiction, but the underlying requirement is consistent: acid sulfate soil risks must be identified and managed before and during site disturbance.
How We Can Help
Confluence Environmental prepares Acid Sulfate Soil Management Plans as part of integrated contaminated land, remediation and environmental assessment services.
Our ASSMP services typically include:
Review of ASS investigations, laboratory results and site conditions
Development of practical, site-specific management measures
Alignment of ASS controls with earthworks, remediation and construction programs
Preparation of clear, regulator-ready ASSMP documentation
Ongoing advisory support during implementation, monitoring and validation
We focus on producing ASSMPs that are practical to implement on site, proportionate to the level of risk and aligned with approval conditions and project delivery requirements.
Related Terms and Concepts
Contaminated Land
Environmental Site Assessment
Preliminary Site Investigation
Detailed Site Investigation
Remediation Action Plan
Soil Classification
Waste Classification
Groundwater Investigation
Groundwater Monitoring Wells
Geotechnical Investigation
Site Validation