An investigation and remediation of TNT contaminated soils.
An investigation and remediation of TNT contaminated soils and wastes was conducted at the Apache Powder Superfund Site in Cochise County, Arizona during 1999 and 2000. TNT contamination was most likely the result of salvage operations of World War I munitions. Characterized by a steep hillside and arroyo cutting through the wastes, the site offered challenges of stability, access, health and safety (from both a toxicity and energetic viewpoint), and regulatory and community concerns.
Prior to invasive activities an unexploded ordnance survey was conducted; no intact ordnance was found. Of particular interest and concern was a layer of relatively pure crystallized TNT. Samples of this material, as well as other representative soils and waste components, were regularly tested on-site for shock sensitivity.
Approximately 85 cubic feet of TNT-contaminated materials, representing 5400 pounds were excavated. This material had an average concentration by weight of 33 percent TNT. This material was burned on-site while air monitoring was conducted through mobile monitoring and at fixed locations. Monitoring was performed to ensure compliance with National standards and State guidelines.
In addition, 1,740,000 pounds of contaminated soil with concentrations less than one percent TNT were excavated and transported offsite. Field immunoassay test kits were utilized to determine soil contamination levels for TNT and DNT. Test kit results were verified with laboratory analyses. The site was remediated to assure the following cleanup levels: 2,4,6-TNT, 33.0 mg/kg; 1,3,5-TNB, 3.3 mg/kg; 2,4-DNT, 140.0 mg/kg; and 2,6-DNT, 28.0 mg/kg.