ABSTRACT
The actual health risk posed collectively by the sites is relatively minor. Explicit inclusion of natural attenuation in the cleanup decision-making process would cause a drastic reduction in cleanup cost, with or without Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) reform. Quantification of natural attenuation might be even more critical for assessment of ecological risk, which is otherwise decided in the absence of numerical targets and guidelines. Natural attenuation of contaminants is arguably a rough litmus test of the resilience and self-cleansing capacity of exceedingly complex soil systems. Numerical assessment of natural attenuation might provide an approximate measure of the specific ecological risk posed by a contaminant. Remediation by natural attenuation generally requires considerable monitoring and results in contaminant reductions while providing tangible public health and environmental benefits. The chapter also presents an overview of the key concepts discussed in this book.
