Reversing contamination Fuel Spill Plume Appears to be WorkingBY DENNIS DOMRZALSKI The Kirtland Air Force Base fuel leak cleanup effort has reached a major milestone -- pulling an underground plume of contaminated water back toward the base and away from city drinking water wells. Air Force and state environment officials said a “cone of depression” has formed around three extraction wells that have been pumping water contaminated with ethylene dibromide. It's a sign that water is flowing toward those three wells and away from drinking water wells. The cone is about 3,500 feet in diameter and covers the northern half of underground plume. “It is a huge milestone, and it is starting to pull it [the plume] back toward the base and away from drinking water wells,” New Mexico Environment Department scientist Dennis McQuillan said Thursday night during an update on the cleanup effort. NMED hydrologist Diane Agnew said the cone's formation indicates that the three extraction wells were properly placed. Officials used computer modeling programs to figure out where to drill the wells so they would have maximum effect. It means the models worked, Agnew said. Agnew added that the formation of the cone was “remarkable considering the short time frame” in which it occurred. The first extraction well began pumping last June, and the two others came online later in the year. And more cleanup efforts will begin later this year. A fourth extraction well will be drilled in late summer, and two pilot programs will begin to see if naturally occurring bacteria in the soil above the spill and in the contaminated water can be encouraged to eat the contaminants at a faster rate. The first effort will involve shooting oxygen into the ground above where the leak occurred on the base. There are still concentrations of aviation fuel in that soil at a depth of 50 to 250 feet, and the oxygen should help the bacteria to grow faster and eat more of the fuel, said Adria Bodour, the Air Force's lead scientist for the cleanup effort. The second plan is to inject nutrients—yeasts, phosphates and sodium lactate—into the area of the plume that contains aviation fuel to see if it will help the bacteria to grow and eat the EDB in the fuel at a faster rate than they are now, Bodour said.
The cleanup will take a long timeDespite the progress, the cleanup effort will take a long time. Air Force and state officials have said that it could take at least 10 years to collapse the EDB plume back onto the base. And officials are still trying to figure out the best way to remove the actual aviation fuel that's still in the water. And while state officials initially said that up to eight extraction wells would be drilled above the EDB plume, it looks like only a fourth well will be drilled. That's because the three wells already in place have created the cone of depression. After the fourth well is drilled, the scientists will let the system work for two years before determining what the next steps should be. The contaminated water is pumped to a treatment facility on base where it is run through two vessels that each contain 20,000 pounds of granulated activated carbon which strips the EDB out of the water. The cleaned water is then piped to an 18-hole golf course on base where it is used for irrigation. During the winter months the water is injected back into the aquifer through a well on base. So far, 79.3 million gallons of water have been pumped and treated, and 26.7 grams of EDB have en removed from that water. The EPA views EDB as a cancer-causing agent in even the most minute amounts. The fuel leak was discovered in 1999, but the fuel had been leaking—possibly for decades—from an underground pipe on base. Although it has been previously estimated that between 6 million and 24 millions of fuel leaked into the aquifer, no one can say for sure.
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