How do you decontaminate soil?


Date: 30/07/2020

There are a diverse number of ways to decontaminate soil. In this blog, we detail everything you need to know about soil decontamination.

Why should I decontaminate soil?

Contaminated soil can be dangerous to livestock and potentially to people through ingesting plants grown in the soil, ingesting water that the soil contaminated, breathing in violates from the soil, or absorbing the contaminants through their skin. When rehabilitating a site after use, it is important to test and decontaminate the soil to prevent health hazards to future inhabitants.

Decontamination methods

Biological treatment/bioremediation

Bioremediation is using bacteria to break down contaminants in the soil. This is effective for soil contaminated with hydrocarbons, halogenated organic solvents, halogenated organic compounds, non-chlorinated pesticides and herbicides, nitrogen compounds, metals (lead, mercury, chromium) and/or radionuclides. Bioremediation is cheaper than other disposal options but can take up to several months to carry out depending on the size of the site.

Chemical oxidation

Chemical oxidation is injecting chemical oxidants into the contaminated soil to destroy contaminants with chemical reactions. In situ chemical oxidation (ISCO) is useful when decontaminating the soil under buildings or deep under the ground. It is effective against TPH, BTEX, PCBs and other organic contaminants.

Soil stabilisation

Soil stabilisation involves one of two things; modifying the soil contaminant to be less dangerous, or locking the contaminant in place so it can’t move into groundwater, air etc. To achieve this, you insert immobilising agents into the soil, which reduces the contaminant’s leachability and bioavailability. You can also use soil stabilisation before you start work on a site to improve the durability and decrease the permeability of the soil.

Physical methods

Physical methods of soil decontamination include soil washing, excavation, constructing barriers around the contaminated soil, capping, soil vapour extraction, electrochemical methods and thermal treatment. Here are some explanations on what each of these do:

Soil washing

Wash the soil with a liquid wash solution. Contaminants will wash away with silts and clays, leaving you with sand and gravel restored to its state before contamination.


Loosen, quarry, load, haul, unload and dispose of the soil.

Constructing barriers

This is useful when your main goal is to stop large-scale contaminant migration.


Prevent precipitation from getting into the soil and creating contaminated groundwater.

Soil vapour extraction

Best for removing highly volatile substances with high vapour pressures from an unsaturated area.

Electrochemical methods

Use electro-kinetic phenomena to remove heavy metals from the soil.

Thermal treatment

Best for removing combustible substances such as solvents, petroleum, coal-derived hydrocarbons, BTEX, aromatics, PAHs, highly volatile CFCs, chlorinated herbicides or pesticides. Be mindful that thermal treatment is expensive, requires multiple treatment steps, often uses additional fuel and can have extra costs in destroying the contaminant after it is removed.

Contact Relient Civil Group

Reach out to the team at Relient Civil to discuss the best soil decontamination method for your next project site. You can speak with us today by giving us a call or filling out our online enquiry form.

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