Acid Sulphate Soil Investigation Triggers
In Queensland, the presence and management of acid sulphate soils (ASS) is a significant environmental concern given the state’s geography and coastal zones. Local councils and the state government have developed guidelines and policies to address the potential risks of ASS disturbance.
While specific triggers can vary slightly between councils based on local conditions and priorities, many councils in Queensland refer to or adopt guidelines and maps provided by the state government. Here are some common triggers that might necessitate an ASS investigation in Queensland councils:
1. Known ASS Risk Zones:
The Queensland government provides ASS risk maps that delineate areas with a high likelihood of containing ASS. If a proposed activity is within one of these mapped areas, it’s a primary trigger for an investigation.
2. Depth of Ground Disturbance:
Activities that involve excavation or disturbance below a specified depth, often around the natural water table (e.g., 1-2 meters in some areas), can prompt an ASS investigation. The rationale is that such disturbances could expose potential ASS to oxygen, starting the acidification process.
3. Water Management Activities:
Proposals that could impact the groundwater or surface water table, such as drainage modifications, dewatering, canal constructions, or dam developments, may require ASS investigations.
4. Land Use Change in Risk Areas:
If a site within an identified risk area is transitioning from one land use to another, especially if the new use could disturb ASS (e.g., converting wetlands to agriculture), an investigation might be triggered.
5. Volume of Soil Disturbance:
Some guidelines might specify a volume threshold for soil disturbance. If you’re moving or excavating beyond this volume in a potential ASS area, an investigation may be needed.
6. Proximity to Sensitive Environments:
Activities near ecologically sensitive environments, like mangroves, wetlands, or coral reefs, might trigger an investigation due to the potential environmental impact of acid leachate.
7. Infrastructure and Development Projects:
Projects that involve extensive groundworks, especially below-ground structures like basements or tunnels, in potential ASS regions can trigger investigations.
8. Previous Reports of ASS:
If nearby areas or adjacent sites have confirmed ASS issues or if historical ASS disturbances have been reported, an investigation might be triggered for new activities.
9. Public or Community Concerns:
Occasionally, local knowledge or community advocacy can be a trigger, especially if there’s a strong public sentiment or historical context for ASS disturbances in the region
As an example, listed below are some council guidelines.
Brisbane City Council:
• Areas identified as having a high or moderate risk of containing ASS in council maps.
• Disturbance or excavation of 100 cubic meters or more of soil.
• Disturbance or excavation below a depth of 2 meters from natural ground level.
• Water table changes, such as drainage or filling, in high or moderate risk areas.
Moreton Bay Council:
• Areas mapped as potential ASS regions.
• Disturbance or excavation of soil from below the natural water table level.
• Activities that could alter the water table, potentially exposing ASS.
• Any development or activity that might disturb a significant volume of soil or go beyond a specific depth in identified risk areas.
Redland City Council:
• Development or ground-disturbing activities in areas mapped as potential ASS risk zones.
• Excavation or disturbance below a specified depth, often linked to the natural water table.
• Activities that change the hydrology, potentially exposing submerged ASS to oxygen.
• Large-scale developments or earthworks in regions identified as having ASS potential.
These are general triggers that might be applicable, but they can change based on new research, findings, and council decisions. For the exact, current requirements, I would recommend consulting the planning and environmental guidelines provided by each individual council or reaching out to the council’s environmental or planning departments directly. They can provide specific documents, maps, and guidelines detailing the triggers for ASS investigations in their respective regions. A link to the Queensland ASS guidelines can be found here.
If you would like to discuss your Acid Sulphate reporting requirements please get in touch here.