Oct 02, 2007

Iowa Army Ammunition Plant Cleanup Continues

The Iowa Army Ammunition Plant is scrubbing its image clean.

This year, the plant will win its eighth straight Des Moines County recycling award. That's a far cry from the early decades, when explosives, solvents and petroleum byproducts swirled into a sour mash that flowed down streams and soaked into soil.

For the past two decades, the plant has been paying for sins in its past with an environmental cleanup that will cost more than $100 million when all is said and done. In 1990, the facility was added to the federal Superfund program, which targets the worst toxic waste sites nationwide.

The site includes a shallow pond known as the Line 800 pink-water lagoon. At one time, trucks laden with toxic waste pulled up to the lagoon's southwest end and dumped their cargo on the ground. The waste then flowed down into the lagoon itself. The pink tinge to the water, which was sometimes much closer to red or even crimson, was caused by the explosive TNT reacting with sunlight.

One problem came when rain made the lagoon rise, causing water to spill over the dam and into Brush Creek, where it began a rapid journey off post. To fix the flaw, plant officials added five settling ponds in the tree line just beyond the dam. The end result was a sort of stair-stepped waterpark of contamination that has challenged the government since 1983.

Workers are now injecting a clear liquid into the pond, pumped from a giant blue tank into the ground. The liquid is a dextrose solution, similar to corn syrup. About 50 gallons will be injected every four feet all the way back up to the surface.

The workers with Tetra Tech, an environmental services company from Tennessee that has taken over the mitigation program for groundwater contamination at the plant, said the dextrose solution feeds invisible microbes occurring naturally in the ground. As the microbes multiply, they starve one another for oxygen. When that happens, they go looking for more, and find it in an explosive called RDX, a possible cancer-causing agent. It is especially difficult to conquer because it mixes with ground or surface water and moves about. But it cannot resist the assault from the gasping microbes, which break it down until it is no longer toxic. It's little wonder, then, that Allison calls the microbes "magic bugs."

Tetra Tech will continue to measure RDX in the groundwater at the site and, if necessary, inject more dextrose solution.

The goal is to get the density of the explosive down to two parts per billion. In an analogy Allison likes to use, that's equivalent to two drops of water in an Olympic-sized swimming pool. The timeline is about 40 years.