WASHINGTON (CN) – Thanks to new clean-up technology, the Visalia Pole Yard has been removed from the Environmental Protection Agency’s list of Superfund sites 80 years ahead of schedule.
The site was used by Southern California Edison to treat utility poles with creosote for nearly 80 years, leaving contaminants as far as 100 feet underground.
When originally designated, the EPA estimated that clean-up at the facility would take up to 100 years, using standard methods such as pump and treat where ground water from the contaminated source is pumped from under the ground and treated on the surface. For the first 20 years of operations at the site, pump and treat methods are estimated to have removed only 10 pounds of hydrocarbons per week. In 1997, however, a new method of clean-up was introduced using superheated steam injected into bore holes around the site which vaporized contaminants that then could be suctioned out of the bore holes.
This method, called thermal dynamic stripping, was developed by the School of Engineering at the University of California, Berkeley in partnership with the Lawrence Livermore National Laboratory. Thermal dynamic stripping worked 5,000 times faster at removing hydrocarbons from the soil and is now commonly used in remediation of contaminated sites, according to the lab’s Web site.
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