|Lawrence Livermore National Lab, https://www.llnl.gov/|
Engineers at Lawrence Livermore National Laboratory used dynamic hydrous pyrolysis/oxidation (HPO), a process invented at the lab, to clean the California Edison’s Visalia Pole Yard more than 100 years ahead of schedule and millions of dollars under budget. The Visalia site had been used for 80 years to treat utility poles by dipping them in creosote or pentachlorophenal. But by the 1970s, these chemicals had seeped into the soil and groundwater to depths of 100 ft. Shortly after this discovery, the four-acre Visalia facility was declared one of the first Superfund cleanup sites.
The cleanup method first used was pump and treat, which involved pumping out the toxic water and soil and treating it to remove hydrocarbons. The process removed about 10 lb/week and experts predicted they would have to build a permanent pump-and-treat facility to keep contaminants from spreading, an option that would cost more than $100 million.
But scientists at Livermore developed HPO, a process in which contaminants are turned into carbon dioxide, chloride ions, and water using injected heat and oxygen. This process removed 46,000 lb of hydrocarbons weekly. And after HPO, the site’s groundwater meets drinking-water standards. Total clean up took 10 years and cost $14 million.