Lime Treatment for Containment of Source Zone Energetics Contamination: Mesocosm Study

Abstract

This research examined basic and applied aspects of the application of an alkaline source to soil in order to reduce the source zone contamination on live fire ranges and contaminant transport into groundwater. Mesocosms were prepared using soil contaminated with hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), 2,4,6-trinitrotoluene (TNT), and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) at 38, 11, and 4mg∕kg, respectively, in order to evaluate removal using several alkaline materials. Alkaline application methods examined included topical, well-mixed, and aqueous. These studies were supported by microbiological and toxicological assessments. Well-mixed soil–lime systems yielded high soil pH (>12) and complete removal of TNT, RDX, and HMX from both soil and leachate by 2, 4, and 18 weeks, respectively. The pH of soil and leachate of topical application systems remained similar to the control (pH 5–6). The occurrence of RDX degradation products and anoxic leachate indicated that anaerobic biodegradation had occurred in several of the topical application mesocosms and contributed to explosive removal. The efficacy of the alkaline hydrolysis reaction in soil is indicated by the initial soil pH, and the degree of base saturation.