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4.4.1 Effectiveness in remediation the contamination

The term ‘effectiveness’ is a measure of the ability of a technology to remove or reduce contaminants to prevent exposure or undue detriment to other properties of the site. There is often a preference amongst regulatory bodies for selecting remedial actions that employ treatment technologies that, as their principal element, permanently and significantly reduce the toxicity, mobility or volume of the hazardous contaminants. Permanent and significant reductions can be achieved through destroying toxic contaminants, reducing total mass, irreversibly reducing the contaminant mobility or reducing the total volume of contaminated media. This criterion focuses the evaluation of an alternative on a variety of specific factors [IAEA-2006b]:

  • Treatment processes used and materials they treat;
  • Amount of hazardous materials destroyed or treated;
  • Degree of expected reduction in toxicity, mobility or volume described as a percentage of reduction;
  • Degree to which the treatment is irreversible;
  • Type and quantity of treatment residuals that remain following treatment;
  • Ability of the alternative to satisfy the statutory preference for treatment as a principal element.

Another key objective is often that the remediation should not only improve the situation by eliminating contaminant exposure pathways for health risk but also not be detrimental to the long term environmental qualities of the site. For example, the functionality of soils has to be retained to avoid unnecessary restrictions on future land use.

Another factor to consider in assessing long term effectiveness is the magnitude of the residual risk, i.e., the risk remaining from untreated wastes or treatment residuals remaining after remedial activities have been completed. The characteristics of the residual wastes need to be considered to the degree that they remain hazardous, taking into account their volume, toxicity, mobility and any propensity to bio-accumulate.

The adequacy and reliability of controls, for example, containment systems and institutional controls used to manage the residual risks need to be considered. These include the long term reliability of the management controls necessary for continued protection from residual risk and assessment of the potential needs for maintaining and replacing the technical components of the remedial solution.

Site specific considerations have an impact on the effectiveness and efficiency of the chosen remediation method. Because the mineralogical and geochemical characteristics of the contaminant vary among contaminated sites, remediation methods are not universally effective and efficient. Methods to model and predict the effectiveness of technologies under consideration have been developed. The anticipated performance of a given technique can be simulated and compared with similar results from other techniques to facilitate the selection. The remediation action will be complemented by a post-remediation assessment and monitoring programme to assure its efficacy and that may also be part of any institutional control required on residual contamination.

Steps have already been undertaken to incorporate remediation activities into the ISO 9000 quality management systems. Record keeping is an integral part of quality assurance and quality control. It is essential that records are kept of remedial actions undertaken, so that at any later point in time their performance can be evaluated against that of the original design. Having comprehensive documentation available also facilitates interventions in the case of unsatisfactory performance.