Purpose:

Explosives are the largest environmental contamination problem at U.S. Department of Defense (DoD) sites and can cause toxic hazards, depending on the concentrations present. Where contamination poses a potential threat to a local population and/or environment, treatment of the contaminated soil may be necessary. At the Iowa Army Ammunition Plant in Middletown, Iowa, ESTCP is demonstrating a promising new technology to remediate explosives-contaminated soil using cost-effective, enhanced biological processes.

Description:

In the soil slurry biotreatment process, explosives-contaminated soils are biologically treated in a tank (also called a reactor). Contaminated soils are excavated and prescreened to remove large rocks and debris. The soils are mixed with water to produce a water-based slurry (typically 10 to 40 percent solids by weight) and pumped into the reactors. Within the soil slurry reactor, soils/sludges are combined with water and nutrients to enhance the ability of soil microbes to destroy organic explosives compounds such as TNT, RDX, and HMX. The reactors are designed with various process controls so that temperature, mixing, etc., can be accurately controlled to achieve maximum remediation efficiency. After biological treatment, the soil is dried and tested to ensure that the explosives have been completely treated; the soil may then be removed or put back in its original location. Design, installation, operation, and completion of the demonstration is expected to take 2 years.

Benefits:

Although incineration is the current proven treatment technology, the costs are high, and public acceptance of this treatment method has diminished. Slurry reactor treatment is expected to cut costs by about one-third, relative to incineration (from $300 per ton of soil to around $200). At 24 Army sites already identified, savings could exceed $80 million. In addition, the biological treatment of soil does not require intrusive equipment or unpopular smoke stacks that can be seen for miles.

Contact:

Mr. Mark L. Hampton
USAEC
Building E4430
Attn: SFIM-AEC-ETD
Aberdeen Proving Ground, MD 21010-5401
Telephone: (410) 436-6852
Fax: (410) 436-6836
E-mail: mlhampto@aec2.apgea.army.mil