Acid Sulphate Soils Guideline

Preparation of acid sulfate soil management plan (ASSMP)


Management Plan

Further Information



Preparation of acid sulfate soil management plan (ASSMP)

3.0 Format of the management plan

The following is a suggested format for an ASSMP, designed to ensure adequate detail has been provided to demonstrate that the proposed mitigation of potential impacts will result in appropriate management strategies.

An ASSMP must provide:

  • evidence of practical and achievable plans for the management of the project to ensure that environmental impacts are minimised by producing an integrated plan for comprehensive monitoring and control of construction and operational impacts;

  • a framework to confirm compliance with approval conditions stipulated by the local and State authorities; and

  • the community with evidence of the management of the project in an environmentally acceptable manner.

4.0 Components of the management plan

The ASSMP component should be prepared, and implemented prior to soil drainage or disturbance and should contain the following:

4.1   An overview of the physical characteristics and environmental attributes of the site, including:

  • a description of the geology and hydrogeology of the site;

  • the presence of sensitive environmental receptors including surface water bodies and groundwater abstraction bores; and

  • a description of current and historical land use in the area.

A two dimensional diagram of the occurrence of ASS to 1 metre below the depth of disturbance. The map should identify separate areas of both actual ASS and potential ASS according to the upper depth of occurrence e.g. 0-0.5 m, 0.5-1 m, 1-1.5 m, etc. This will assist greatly in understanding the site and form the basis for ASS management;

A description of the occurrence of ASS on the site, including;

  • vertical and spatial distribution of ASS;

  • a map of the site distribution of ASS; and

  • results of the preliminary ASS assessment.

An overview of the proposed works including:

  • the dewatering and drainage strategies;

  • the soil excavation strategy;

  • delineation of any clay and peat lenses and horizons that may affect dewatering or excavation of soil;

  • temporary storage of ASS, if proposed; and

  • reuse / disposal of excavated ASS.

Details of the potential on-site and off-site effects of the disturbance of the soil and/or the groundwater levels;

A description of the management strategies to minimise impacts from the site works including:

  • strategies for preventing the oxidation of iron sulfides (including avoiding the disturbance of ASS by redesigning layout of the excavations and/or re-flooding of potential ASS to limit oxidation);

  • treatment strategies for ASS (including neutralisation of ASS, use of lime/limestone barriers, burial of potential ASS);

  • strategies for management of the watertable level on and off-site both during and post construction; and

  • containment strategies to ensure that all contaminated stormwater and acidic leachate associated with the oxidation of ASS is prevented from entering the environment both in the short and long-term;

Timing (milestones) of environmental management initiatives;

Performance criteria to be used to assess the effectiveness of the ASS management and monitoring measures;

A comprehensive monitoring program for soils and surface and ground water quality should be designed to enable the effectiveness of the management strategy to be assessed. Depending on the type or scale of the proposal and sensitivity of the location, the following should be included:

  • monitoring locations;

  • monitoring frequency;

  • sampling and analytical parameters (as a minimum requirement, parameters should include pH, electrical conductivity or Total Dissolved Solids (TDS), sulfate, chloride, iron, arsenic, aluminium, POCAS (Peroxide Oxidation Combined Acidity and Sulfate) and TOS (Total Oxidisable Sulfur); and

  • procedures to be undertaken in the event the monitoring indicates exceedance of threshold or water quality criteria.

Description of the pilot project or field trial (if conducted) to:

  • prove the effectiveness and the feasibility of the selected management procedures to deal with ASS and their environmental impacts;

  • demonstrate that the proponent has the capability to implement those management procedures effectively; and

  • demonstrate the ability to comply with agreed standards and performance targets.

Description of the contingency procedures to be implemented on the site to deal with unexpected events or in the event of failure of management procedures, including a remedial action and restoration plan related to:

  • any failure to implement any proposed ASS management strategies; and

  • any mitigation strategies that are ineffective so that the project fails to meet agreed standards or performance levels.

Outline of reporting procedures for meeting environmental performance objectives and demonstrating quality assurance to relevant authorities and the community.

5.0 Review of management plan

The management plan should be reviewed and periodically updated to reflect knowledge gained during the course of operations and to reflect new knowledge and changed community standards (values).

Changes to the management plan should be developed and implemented in consultation with relevant authorities.

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