Low-order detonation (LOD) debris is a potential source of contamination to groundwater beneath live-fire testing and training ranges. During range clearance activities, explosive ordnance disposal personnel are required to segregate all scrap with visible, residual energetic materials (EM) or hidden recesses and treat it as unexploded ordnance (UXO). Under existing regulations, these items are not permitted for removal from the range and many have simply been “blown-in-place” using a supplemental charge or gunfire. Neither produces a reliable high-order detonation. As a result, large quantities of additional residual EM are dispersed around ranges. Even large chunks of EM ejected from LOD normally are left in place. The potential for groundwater contamination from these bulk compositions is many times greater than the widely dispersed, low-level contamination created by high-order detonations.
Building on SERDP SEED project MR-1196, this project sought to develop a low-cost, fieldable process, using decomposition and base hydrolysis, for the rapid decontamination of EM present in bulk compositions and LOD debris. Data were acquired to evaluate chemical and biological processes for treating decontamination solutions on-site so no hazardous wastes require disposal.
In this process, LOD debris and large chunks of EM are placed in a decomposition/hydrolysis vessel. Water is added to cover the EM and heated to 100/C. The EM decomposes, falling away from the scrap. Vigorous stirring emulsifies melted TNT and suspends crystals of RDX. Potassium hydroxide pellets are added slowly to maintain controlled reaction rates at a pH less than 11. The hydrolysate is delivered at atmospheric pressure to a 700/C calcium carbonate catalyst bed in a catalytic hydrothermal conversion (CHTC) unit, where gasification and steam reforming produce aggressive oxidative conditions. A safe and controlled reaction rate is maintained in the catalyst bed by adjusting the feed-rate of hydrolysate using temperaturefeedback circuits. After the hydrolysate is consumed, the treated scrap is rinsed with fresh water, tested with on-site EM colorimetric methods, and eventually recycled.
This project developed a decomposition/hydrolysis solution that was far simpler, less expensive, and more effective than originally proposed. Hot water and the controlled addition of hydroxide pellets were sufficient to remove detonable quantities of EM from metallic range debris and to treat chunks of EM ejected from LOD. A total material cost of $4,200 was incurred for construction of the prototype CHTC unit, which can treat up to 16 kilograms of EM per day and produces no solid or liquid waste.
The flexibility, safety, simplicity, and low costs associated with this decontamination technology will facilitate its use by site personnel. The technology effectively treats the most contaminated materials, thereby reducing UXO cleanup costs and alleviating the need for wide-area decontamination. (Project Completed - 2004)