Do-Nothing Cleanups

by Randall T. Hicks, Vice President; Geoscience Consultants, Ltd., Albuquerque, NM,
Rais Rizvi, Proj. Engr.; Geoscience Consultants, Ltd., Albuquerque, NM,

Serial Information: Civil Engineering—ASCE, 1996, Vol. 66, Issue 9, Pg. 54-57

Document Type: Feature article


Restoring polluted soil and ground water to pristine condition is, in some cases, neither cost-effective nor feasible. So what's the best way to close these sites with minimal overall health risk? At certain sites, the best approach is to do nothing and allow nature to do all the work. This process is called intrinsic remediation, and in the past few years, the regulatory climate has changed to encourage its use. Although it goes against the grain of conventional wisdom, letting toxins decompose naturally can, in some cases, reduce the site's overall cost and pollution burden. For instance, maintaining and operating a pump-and-treat ground-water remediation system requires electrical energy, vehicles to transport samples and the staff, and landfill disposal of the spent carbon filters. Removing 10 g of benzene from an aquifer could require treating 1,000,000 gal. of ground water and ultimately create more pollution, in the form of powerplant emissions that contain carbon monoxide and ozone, and even more benzene than was removed from the site. By contrast, intrinsic remediation relies on a two-pronged approach to site closure. The first is to make sure that any analysis of the site takes into account the biological and geochemical processes that contain the spread of contaminants and break them down naturally. The second is to set up institutional controls, such as new zoning regulations for the affected sites, that minimize the risk of public exposure to the toxins while they're decomposing.

Subject Headings: Groundwater pollution | Soil pollution | Mitigation and remediation | Water pollution | Health hazards | Electrical systems | Electric power

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