Contaminated land: issues and practical considerations

Contaminated land:

issues and practical considerations

This can be the result of historic or current site activities, including incidents during the manufacturing, handling and storage of hazardous substances,” says Lindsay Shand, principal environmental geologist at SRK Consulting. “Various activities have the potential to contaminate land, such as manufacturing, mineral extraction, abandonment of mines, waste disposal, accidental spills, illegal dumping, leaking underground storage tanks, floods, pesticide use, and fertiliser application.” Contaminated land is not rare, and almost every industry must deal with it. Industrial sites have traditionally been built on the outskirts of towns and cities, but urban expansion has seen many housing projects being built on or next to industrial areas. Today, many industrial sites are in the centre of towns and cities. Contaminated land is required to be declared to the Department of Forestry, Fisheries and the Environment (DFFE) under Part 8 of the National Environmental Management: Waste Act (No. 59 of 2008; NEMWA).

Shand adds that resolving land contamination issues requires a detailed understanding of the chemistry and geology to fully comprehend and contextualise the risks associated with the contamination. It is also vital to

The contamination of land by hazardous substances may involve contaminated topsoils or subsurface soils that can leach toxic chemicals into develop a robust site conceptual model nearby groundwater or surface that describes the potential receptors water – affecting plants, animals and humans. at risk and forms the basis of the remediation action plan (RAP). This RAP informs the remediation order issued by By Kirsten Kelly the DFFE. Issues and practical considerations Water stewardship: Soil, groundwater and surface water are closely interlinked. Water stewardship provides the necessary integrated systems approach for the management of these resources. “Water stewardship encourages one to consider the catchment area and understand your water use, as well as contamination risks to the immediate environment and catchment area. It improves the management of contamination risks, operations and water,” states Shand.

Lindsay Shand, principal environmental geologist, SRK Consulting

Surface water quality sampling at a lake Photo credits: SRK Consulting

Soil remediation and chemical treatments: “In order to formulate a remediation plan, one needs adequate data from a site assessment. There is no ‘quick fix’ to a contamination problem that has developed over a long period of time,” adds Shand.

“While good chemical treatment processes are available, they need to be utilised carefully. One must make sure that the chemical treatment itself does not have a negative effect on groundwater or soil chemistry. Remediation can take time to achieve its goals,” she says.

SRK uses a team of geologists, geochemists, microbiologists, hydrogeologists and engineers to find the best possible solution, or combination of solutions, to any contamination problem. “There are many options available, such as natural attenuation, where, for instance, microbial populations in the soil are developed to contribute toward pollutant degradation,” explains Shand. “There are also engineering controls like barriers to prevent fresh groundwater from coming into contact with polluted groundwater, by diverting the polluted groundwater into a sump and treating it either in situ or at a wastewater treatment works.”

Linking of sciences: Dealing with land contamination is a complex matter, and requires collaborative efforts of physical, chemical and biological scientists to work in interdisciplinary teams. “Many of the sciences cross over and it is important to consider the bigger picture,” states Shand.

Due diligence: For developers, due diligence is paramount, first to establish whether there is any contamination of the site intended for development, and then to investigate the most appropriate mitigation options. Understanding the actual risks allows for a tailored approach in controlling these liabilities.

“Often, land contamination teams are not consulted at the beginning of a project when it is critical to test for contamination, as this affects future site planning and management. Land contamination specialists can conduct site assessments to help identify where contamination risks may lie. This can lead to considerable cost savings if it can guide a developer to certain, more suitable, land-use types. It may be that at a parking lot, light industrial land use may be more appropriate than digging into contaminated areas for residential purposes – which may require more onerous contamination management procedures,” says Shand.

Regulations: Contaminated land is managed under the NEMWA, in accordance with guidance from the DFFE in the Framework for the Management of Contaminated Land. An environmental site assessment will determine if the land is contaminated and the extent of the risk. Once authorities are notified of the contamination and potential risks, the landowner will receive a remediation order where they are then required to undertake an additional assessment or to implement the proposed remediation.

Stakeholder involvement: “It is critical to develop good relationships with all stakeholders when dealing with land contamination. Contamination that has extended to third parties can derail project timelines and result in reputational damage. By being proactive and forming engaging relationships, one begins to build trust,” adds Shand.

Offering SRK has extensive experience in land contamination and uses a multidisciplinary team to: • undertake due diligence work where the level of contamination risk is determined through soil surface water and groundwater surveys, as well as through risk assessment and modelling • notify and liaise with the authorities about appropriate remedial alternatives to be considered • reduce environmental and health risks through the identification and implementation of costeffective remediation strategies based on extensive technical and regulatory knowledge • conduct groundwater modelling • provide on-site supervision and monitoring.

SRK Consulting undertakes water quality risk assessments and audits – pictured here is a tailings facility SRK Consulting has undertaken contamination site assessment soil sampling in Cape Town