No two contaminated sites are alike and therefore require different forms of treatment. In many cases the type of contaminant present and its behaviour in the underground aquifers will dictate which form of treatment is most suitable.

Pump-and-Treat for Heavy Metals

Heavy metals and inorganic salts are usually removed from solution as part of a Pump-and-Treat system. These systems work best where there is a clear plume and the aquifer is productive enough to allow extraction of sufficient amounts of contaminated groundwater for treatment above ground.

ISCO for Petroleum Hydrocarbons

In-situ chemical oxidation can be the fastest form of remediation for petroleum hydrocarbon spills as it can immediately begin to degrade the fuel at the source of the spill. This form of remediation works best in permeable soils such as sands as the chemical can be most effectively distributed throughout the contaminated ground.

Permeable Reactive Barriers for Chlorinated Solvents

A permeable reactive barrier can be designed to intercept a contaminant plume and remove chlorinated solvents and industrial chemicals. Zero-valent iron (Fe0) is the most common fill material for these types of systems as it can effectively degrade many chlorinated compounds.

Bioremediation for BTEX and Organic Contaminants

Bioremediation methods utilise naturally-occurring microbes to degrade a wide array of organic contaminants including BTEX compounds. As concentrations decline below the threshold for remediation, the site can be left to monitored natural attenuation (MNA) without further intervention.

Stabilisation for Mixed Heavy-Metal Sites

Stabilisation and immobilisation for heavy metals and other mixed contamination sites will ‘stabilise’ the metals in place to stop them migrating, rather than a costly exercise to try and extract them all.

Air Sparging for VOCs

Air Sparging involves introducing air below the water table in the groundwater. The volatile compounds will change from a liquid to a gas and rise through the soil as a vapour. These vapours are then collected by a vapour extraction system. Further information on Air Sparging as well as other groundwater remediation technologies can be found in the remediation technology overviews published by the US EPA.

A useful reference for Groundwater Remediation is //soilfix.co.uk/services/groundwater-remediation/.

Some aspects of contaminated site cleanup depend on the type of contaminant, the type of soil in which the contaminant has been left to leach, and the extent to which the contaminant has spread as a plume in the soil.