What is the objective?
Contaminated soil removal from old petrol filling station in central London
Firstly it is not to create a perfectly clean site or uncontaminated site. All manner of contaminants exist in the ground which generally do not cause any significant harm; however in certain circumstances and in certain concentrations they may cause harm. The aim is to prevent the contaminants reaching the people, plants or waterways that might be adversely affected.
The appropriate remediation strategy will be influenced by the site use, remediation for a commercial use would probably look very different from that for a residential use of the same land.
How might this be done?
Removal of contaminated soil, Ducklington, Oxfordshire
Frequently it is done by removing the contaminated soil and disposing of it in a licensed landfill.
It can sometimes be done by treating the soil on site. This may or may not be practical depending upon the type of contaminants and size of site.
It may be possible to introduce a barrier between the contaminants and people who will be using the site. This barrier may be a purpose made membrane, a hard surface such as block paving or asphalt or a suitable depth of clean soil.
Installation of barrier with capillary break and clean top soil, Ducklington, Oxfordshire
The contaminated areas may be suitable for some uses but not others, in which case it may be possible to amend the site layout so that for example the contaminated area is used as a car park instead of gardens.