Sandia Natural Attenuation Project

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Patrick V. Brady

Natural Attenuation

Natural attenuation means dilution, dispersion, (bio)degradation, irreversible sorption, and/or radioactive decay of contaminants in soils and groundwaters. Natural attenuation causes a net reduction of contaminant toxicity and human and ecological risk, but is rarely taken advantage of in environmental remediation. Instead contaminants in the subsurface are assumed to be 'time bombs' having near eternal lethality. In fact, most contaminants in soils and groundwaters are naturally attenuated rapidly, and far faster than they can be removed by engineered remediation schemes. A science-based approach to remediation would be to ignore those contaminants which are naturally attenuated, remediate those which aren't, if it can be shown that remediation actually works (often it doesn't), and limit future exposure from the sites which remain. The present approach generally requires at least the attempt to remove all contaminants and will achieve minor decreases in health (human + environmental) risk but has been estimated to ultimately cost a trillion dollars.

The Sandia Natural Attenuation Project is a three year program by Sandia National Laboratories to identify the mechanistic controls on metal and organic attenuation by irreversible sorption in the subsurface. SNAP will provide a scientific basis for risk-based corrective actions by helping identify only those sites where contaminants can be expected to impact the biosphere and where Monitored Natural Attenuation (MNA) is likely to be most effective.

Inquiries about SNAP may be sent to Pat Brady.

For more background information on Natural Attenuation

Geochemistry Dept.

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Last modified: November 15, 2000

The SNAP Homepage has been accessed times since February 28, 1997