Explosives remediation is a very specialized niche, because few organizations work with stakeholders that have explosives as primary contaminants. We are fortunate that in our academic capacity we research and develop new explosives remediation strategies under the Strategic Environmental Research and Development Program (SERDP), which can be applied in practice.
This site was a manufacturing and loading facility, at which the cyclic nitramine RDX had contaminated both soil and groundwater. We were tasked with developing a sampling and analysis plan to determine if the site conditions were conducive to natural attenuation, or if an engineered strategy was going to be required.
Ultimately we selected a combined remediation approach based on bioremediation and secondary chemical reactions with ferrous iron, mediated by Fe(III)-reducing microorganisms. The low molecular mass electron donor acetate was amended into the groundwater to promote ferric iron respiration, and the reactive ferrous iron species reduced the RDX to nitroso intermediates, which could then break down to innocuous end products. This approach worked very well in the anoxic and moderately oxic saturated zone. Soil RDX was different because it was primarily sorbed to the solids, with little moisture in the soil. We selected chemical oxidation of RDX in the soil, to more directly address the shallow contamination without having to desorb the RDX or try and deliver aqueous amendments.