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Interested in retaining your contaminated soils on site? 

Soilutions have the knowledge and practice of stabilising and solidifying contaminated soils, in-situ and ex-situ, for retention on site and as a pre-treatment for off-site disposal.  The basics are explained below, if you're just/more interested in site specific applicability and cost drop us an e-mail or pick up the phone (0131 538 8456), we're always happy to help.

What is soil stabilisation / solidification?

Stabilisation and solidification of contaminated soils are remediation techniques used to reduce a contaminants mobility in soils.  This is achieved by adding binding agents to form either a chemically stable constituent (stabilise), or to encapsulate (solidify) the contaminant in a solidified matrix. 

Stabilisation / solidification can be used to treat soils contaminated by inorganic and/or organic pollutants.

The Science behind it!

Stabilisation and solidification, we'll discuss both as 'STABILISATION' below.

Stabilisation relies on the addition of immobilizing agents which reduce a contaminants leachability and bioavailability, this can be achieved using one of the following processes:

• adsorption to mineral surfaces,
• formation of stable complexes with organic ligands,
• surface precipitation and ion exchange;
• precipitation as salts

The stabilisation processes are influenced by many factors: pH, redox potential, soil organic matter content, cation exchange capacity, sulphides content etc,

Treatment Applications

Stabilisation techniques have been used for treating a wide range of inorganic contaminants and some organic contaminants, including:

• metals and metalloids;
• asbestos;
• radionuclides;
• inorganic corrosives;
• inorganic cyanides;
• solid organics (e.g. plastics, resins, tars);
• polychlorinated biphenyls (PCBs);
• polyaromatic hydrocarbons (PAHs); and
• dioxins.

Treatability study

The selection of immobilizing agent depends on several factors such as, the type of contaminant, the initial contamination levels, the chemical-physical characteristics of the soil as well as the required target reduction. Thus a treatability study should be undertaken in order to demonstrate the efficiency of the potential suitable binders before finalising the design for full-scale implementations.

Application

Stabilisation can be performed either in situ (in the ground) or ex situ (out of the grouns) often depending on the aim of the stabilisation process as well as the regulatory program under which the work is performed.

Advantages and disadvantages of soil stabilisation

Advantages

• the contaminant can be stabilised in a relatively short time period
• stabilisation can be used to treat persistent contaminants (e.g. heavy metals, PCBs, dioxins)
• can be performed both in-situ or ex-situ
• process equipment can occupy a relatively small footprint
• the structural properties of the soil may be improved by treatment (e.g. strength, permeability)
• the stabilised soil can be reused for construction applications or disposed of in a landfill for inert wastes
• much greater cost certainty than the most other remediation options

Disadvantages

• does not destroy or remove the contaminants
• can be difficult to predict long-term behaviour
• may require long-term maintenance of protection systems and/or long-term monitoring.
• potentially significant final volume increase

Heavy metal & hydrocarbon contaminated sludge