Pilot-Scale Demonstration of In Situ Chemical Reduction Technology at a Formerly Used Defense Site

This paper describes results of the first field demonstration conducted to evaluate an innovative in situ chemical reduction technology to rapidly degrade 81?m² of high concentrations of explosives contaminated soils at Ravenna Army Ammunition Plant, Ravenna, Ohio, USA. The primary explosives of concern and associated baseline levels of contamination were 2,4,6-trinitrotoluene (TNT) (383?mg/kg), hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) (180?mg/kg), and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) (15?mg/kg). The in situ chemical treatment process involved selected reductant of sodium hydrosulfite (Na₂S₂O₄) at optimal pH (9?C10) with appropriate buffers (e.g., sodium bicarbonate and potassium carbonate) that, when mixed with water, generate free radicals that react very rapidly to degrade nitroaromatics to carbon dioxide (CO₂), formate (HCOO?C), and gaseous nitrogen compounds (NOx). Significant reductions in TNT, RDX, and HMX (>95?%) were observed within 24?h and achieved response complete in under 2?weeks after in situ application of the buffered sodium hydrosulfite.