Soil remediation, from an environmental perspective, is the reduction of contaminant concentrations within soil.
Why remediate soils?
The aim of soil remediation works in the majority of cases is to reduce contaminants to levels which are ‘suitable for use’, essentially meaning you can use your site without environmental risks. As an example a client contacts us following the identification of an environmental risk. Concentrations of hydrocarbons in soils have been confirmed as being above safe levels for human health and as such must be dealt with before development of the site as a residential housing estate. In this situation remediation of soils may be a condition for planning consent.
The solution to many contamination issues can be found in natural (biological) processes, this is called Bioremediation. Bioremediation involves enhancing / controlling biological processes to reduce the contaminants of concern to target levels.
Bioremediation is widely used to remediate organic contaminants (e.g. fuel and fuel oils), in general bioremediation is a significantly more economic option to straight disposal, however it can take anything from 1 month to several months to carry out. Its suitability is based on the contaminants, site conditions, and target levels. If you want to find out if bioremediation is an option for your site then you should phone or e-mail us, we’re always happy to discuss a site with you.
Soil Chemical Oxidation
Chemical oxidation (chemox for short) is the most common form of soil treatment. Other forms of treatment include the chemical reduction of contaminants, and enhanced natural attenuation where appropriately selected materials are injected to achieve remedial targets.
Chemox involves oxidising contaminants with the purpose of reducing the concentration. The main benefits of Chemox are that contaminated soil and water can be treated in-situ (in the ground), and in difficult to access area. Applying the chemical through injection lances (at pressure) essentially means that if the materials are accessible with a drill rig, then they can be treated with chemox. As usual the suitability of chemox for your site depends on many factors.
Environmental stabilisation of soils is carried out with the intention of tieing up contamination so that the risk from contamination is removed. This should facilitate the re-use of soils, removing disposal and subsequent material replacement costs.
Stabilisation treatment can give 2 benefits, removing the risk from contaminated ground and improved geotechnical competency of the ground. Soil stabilisation come in 2 main forms, stabilisation and solidification.
Stabilisation involves the stabilisation of the contaminant in the ground. This often is designed to change the contaminant from a dangerous form in to a less dangerous form.
Solidification involves reducing the mobility of the contaminant i.e. locking the contaminant in place to it can’t reach any receptors.
Washing soils is more often than not about sorting soils into different constituent parts, gravels, sands and other fines.The majority of contaminants are usually found in the fines, leaving you with clean sand and gravel following washing, materials easy to re-use or dispose of.
Soil washing is ideal for reducing disposal volumes, although the resulting contaminated materials can often be ‘treated’ using bioremediation or chemox for example.
Thermal desorption is a process where heat is used to remove contaminants from soil.
Heating certain contaminants will reduce their concentrations. The most common use of thermal desorption is to treat hydrocarbon contamination (e.g. petrol and diesel).
Desorbed contaminants can often be recovered for re-use.
Contact us today so together we can work out the process that works best for your site