Every time you drive past a large construction site, you will likely see trucks loaded with tons of soil being driven away from the site. Have you ever wondered where all these soils go? In the construction industry, where these site-derived-soils are sent to is usually determined through a process called soil sampling.
What is soil sampling?
Soil sampling, also known as soil testing, is used to determine concentrations of contaminants within soil properties at a specific site. This process typically involves the retrieval of soil samples and submission to a NATA accredited laboratory for analysis.
Why is soil sampling required?
In Victoria, in situations where the soil must be disposed of, soil sampling is conducted to enable soil classification in accordance with the general environmental duty under the Environment Protection Act 2017 and subordinate legislation, Environment Protection Regulations and Environmental Reference Standard. Once the soil is classified, determining where it will go and how much it would cost to dispose is dependent on relevant waste classification guidelines.
Why does soil sampling affect soil disposal and its price?
In some parts of Melbourne that were historically industrial, soil contamination from old industrial waste and historical land uses is common. Soil samples from these locations can contain materials such as asbestos, coke, slag, hydrocarbons, and metals – some of which are hazardous to human health. The more hazardous or contaminated the soil is, the more expensive it will be to get rid of. Where possible, the Environmental Protection Authority (EPA) strongly suggests sticking to the five stages of the waste hierarchy – Prevention, Reuse, Recycle, Recovery and then finally, Disposal. The further down the hierarchy you go, the higher your EPA fees. Soil disposal costs in Australia can range between $20-60 per tonne for clean natural soil but can go up to $1,000 for contaminated soil.
What’s so bad about contaminated soil?
If you’re wondering why the costs of disposing contaminated soils are so high, well, the EPA has very valid reasons for that. Not only does the disposal of contaminated soil affect landfill management issues such as the lack of landfill space and increased transportation risks but disposal of contaminated soils poses risk to future users of land, surface water and groundwater if not managed appropriately.
Landfills licensed to receive contaminated soils are specifically engineered and designed to receive and manage contaminated wastes. The level and type of contamination changes the minimum management requirements and costs for storage or treatment of contamination.
Moving the contaminants from the construction site to a landfill area far away might not pose risks to the construction area directly but in the long run, may impact other humans or ecological receptors if not managed appropriately.
Some common effects of soil contamination are:
- Metal poisoning: Heavy metals can leach through soils and make their way into groundwater storages and nearby rivers which eventually get absorbed by humans, flora and fauna. The absorption of these pollutants can then make their way through the food chain, resulting in the further poisoning of animals and eventually, humans.
- Reduced agriculture: Different plants have different soil requirements to grow and flourish. In areas where the soil is heavily contaminated, plants are likely to die if they are unable to cope with the rapid change in chemical composition.
- Air pollution: Another way toxins can leach is through the air. Contaminants in the soil can get picked up through the winds and get carried to much wider areas.
How can we reduce soil disposal costs?
Characterising your waste early in your construction process is key to ensuring effective and cost-efficient solutions are put in place depending on your needs. Conducting soil sampling early ensures the construction management team is aware of how to best handle the excavation process. The good news is, in the many samples taken from different parts of a construction site, can allow for lateral and vertical delineation of contamination, depending on its historical source. Some parts can be more contaminated than others and should be treated differently. Excavating the entire lot without proper analysis can result in the entire site being classified as contaminated.
Looking into options such as retaining clean soils in the area for landscaping purposes, using onsite containment cells to separate soils of different contamination levels, and subdividing the site into lots depending on the soil for treatment can reduce the amount of soil that will fall on the hazardous ends of the waste category. Essentially, following the EPA guidelines and waste hierarchy is the best way to reduce costs relating to soil disposals.
Are you looking for offsite disposal solutions?
At Alpha Environmental, we have a team of professional environmental consultants that can advise on waste reuse and management to ensure you have the most sustainable and cost-effective solution for your needs. Our friendly team will also help navigate all the requirements, exemptions and approvals involved in your soil disposal to ensure your project runs smoothly with minimal costs and disruption.