Clean up contaminated sites

Natural attenuation is the reduction of mass, mobility or toxicity of site contaminants by the naturally occurring processes of biodegradation, dilution, dispersion, adsorption, volatilization and chemical stabilization. It is a cost-effective and feasible site-remediation option if contaminant reduction occurs within a reasonable time-frame without causing any detrimental effects to human health and local ecological systems. To comply with environmental regulations, a systematic procedure is needed to monitor the extent of contamination, the associated risk, and the effectiveness of natural attenuation. Existing procedures suffer from shortcomings related to duration and cost. This article presents a new modular methodology for risk-based monitored natural attenuation. This approach has been used successfully to evaluate previous site-remediation projects and has been found to save both time and money.