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Industrial use of sites often leaves traces of undesirable, chemical contaminants that must be rendered safe prior to redevelopment for alternate use.

Proper procedures are needed to accurately delineate the type and extent of contamination. The results are then subject to risk analysis, which commences with comparison of contaminant levels to those prescribed as investigation limits by the Australian and New Zealand Environmental Consultative Council (ANZECC).

A health risk analysis is then required to determine the allowable uses of the contaminated areas of site and of the whole site. A crucial step is then determine if the contaminants are bioavailable or able to be released as a toxic media, which may affect human or animal health.

There are several techniques, which can render certain levels of contaminants in soil acceptable for further use without the need for removal. Some of these are:

• Coverage with an inaccessible or impermeable layer, such as concrete or clay.
• Encapsulation of the affected soil to prevent leaching of toxins.
• In situ destruction of the waste biologically, chemically or physically.
• Selected coverage of the contaminated areas .
• Binding the contaminants with other chemicals, or materials such as cement or concrete to immobilise or convert them to safe forms.
• Careful examination of the soil to determine which fraction contains the contaminant and appropriate treatment of extraction, may significantly reduce the amount of material requiring attention.
• Institution of effective site management methods to avoid health and environmental effects.

Cetec has used a number of techniques singly or in combination to create innovative site remediation solutions.

For example, in one site for housing units development  it was more economical to excavate an impervious clay base pit without groundwater and to relocate the contaminated soil into pits on-site and then cover with an adequate layer of impervious clay, rather than remove the soil to an approved tip. Redesign of housing slabs over contaminated areas further reduced the risk to an acceptable level.

In another project, contaminated soil at a primary school was carefully analysed and found to contain the contaminants in a very fine fraction. Separation of this fraction greatly reduced the waste and rendered the residual acceptable for use.

Cetec uses its advanced, scientific and engineering knowledge with its laboratories in Melbourne and Sydney or selected laboratories closer to the project to create cost-effective, safe and innovative solutions to development projects with environmental and health and safety challenges.

To give us feedback on this article or to ask how CETEC can help you then contact us here.