Acid Sulfate Soils (ASS)
Acid Sulfate Soils are naturally occurring and commonly found in low-lying coastal and wetland areas with shallow water tables. When disturbed through excavation or dewatering without proper management, these soils can release sulfuric acid, leading to serious environmental consequences. This acidification can contaminate soil and groundwater, damage ecosystems, and significantly restrict future land use. Responsible handling of ASS is essential to protect both the environment and the long-term value of your land.
While established management practices exist, achieving the most cost-effective and environmentally responsible outcomes begins with accurate site characterisation and thorough risk assessment. Every site is unique, and understanding the specific ASS conditions is critical to developing tailored, practical solutions.
Our team of Environmental specialists brings deep expertise across a wide range of construction projects—from large-scale developments and linear infrastructure to simple site classification.
Leveraging our integrated capabilities in both contracting and treatment, we design and implement effective solutions for managing and treating soil and water impacted during construction—ensuring cost effective compliance, sustainability, and project success.
How can we help you?
During the design and construction of major projects in WA, ASS can present a significant risk to our clients. While the majority consider regulatory approval and compliance to be the highest risk, costs associated with practical identification, treatment and/or disposal tend to overshadow the regulatory component. We have found that regulatory non-compliance is predomonantly associated with poor planning, lack of understanding and, more commonly, insufficient budget.
Tendering on MCPs requires an understanding of the risks and costs associated with managing ASS during construction and is an essential component to project success. Where there is a lack of baseline data, assumptions and project outcome driven modelling (based on years of practical hands on experience) becomes vital for decision making by Commercial and Project Managers.
Engineering Solutions for ASS
We consider managing ASS on construction projects an engineering and sustainability challenge rather than an environmental issue. Where possible, ASS materials should remain onsite and treated if required. However it is more likely that geotechnical and engineering requirements may result in the material being assessed as unfit for re-use on site and removal off-site would need to be considered.
Material can be sent off site for re-use if it meets the criteria for uncontaminated fill as per the WA Landfill Waste Classification and Waste Definitions 1996 (as amended 2019), however there are additional requirements that will have an impact on costs and the project will need to consider the financial implications should the material not meet the reuse criteria and has to be disposed to Landfill (we generally deal with this in the R&O register during tender).
If projects have the space and time, onsite management, treatment and classificaiton for reuse remains the most cost effective and sustainable outcome.
Do we get our hands dirty?
We sure can, Enveng Group can supply the necessary resources to identify, assess and manage ASS and have several key supply chain partners that specialise in the onsite treatment.
We can support your project in a multitude of ways with a focus to reduce time and effort (i.e. cost) while maintaining regulatory and operational compliance. Activities such as:
Tender support - Early works investigations - regulatory engagement - assessments - management and identification during excavation works - treatment - reuse options - disposal - validation and close out reporting.
RELEVANT PROJECTS
