NATURAL ATTENUATION PROTECTED RECEPTORS


In some cases, nature alone will be sufficient to deal with the pollution mass. Monitored Natural Attenuation (MNA) is “a remediation approach based on understanding and quantitatively documenting the naturally occurring processes at a site protecting human and ecological receptors from unacceptable risks of exposure to hazardous contaminants”.


For MNA to be effective as a remedial strategy the rate at which attenuation is proceeding must be sufficient to minimise the expansion of pollutant plumes and protect receptors.


MNA is not a “do nothing” approach. At many, if not most contaminated sites, active remediation can successfully decrease contaminant concentrations, but is unable to achieve regulatory standards. Advanced site diagnostic tools can be used at these sites to gather lines of evidence to demonstrate with greater confidence that naturally occurring processes will reduce contaminant concentrations and accelerate the potential for regulatory acceptance and closure.


Diagnostics tools used by WSP to support MNA programmes include: ƒƒ Measuring bioremediation potential in-situ using bio-traps, including the use of surrogate compounds and non-radioactive isotopes, to track microbiological events


ƒƒ Analysis of DNA, RNA and downstream products such as key enzymes and lipids to enhance the lines of evidence for building the case for Monitored Natural Attenuation.


ƒƒ Use of a variety of non-radioactive isotopes to assess the spatial stability of contaminant plumes.


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