Risk assessment at a JP-4 contamination site after active remediation

Intrinsic bioremediation is a risk management strategy that uses natural attenuation, such as dilution and physical adsorption, and chemical and biological reactions which occur naturally. It has long been recognised that nature has the ability to recover from damage of chemical releases, such as petroleum hydrocarbon spills and leakage from storage and transport facilities. When releases of chemicals to the subsurface environment can impact groundwater quality, natural processes such as biodegradation, dilution, dispersion, sorption and hydrolysis often limit the migration of contaminants in groundwater. Data from several field sites, laboratory studies and computer modeling have demonstrated that natural attenuation can significantly limit the migration of contaminants and reduce the potential impact of hydrocarbon release by preventing contaminants from migrating to sensitive receptors [1]. Intrinsic bioremediation is not a passive `let-it-go’ process, but an active management strategy with monitoring, analysis and planning through the whole period of implementation. A guideline protocol developed for the US Air Force [2] includes various steps for the implementation of intrinsic bioremediation: reviewing site data, developing preliminary conceptual model, performing site characterisations, documenting indicators of intrinsic remediation, modeling and exposure assessment, preparing long-term monitoring plans and alternative remediation plans and, finally, presenting findings to regulatory agencies.