The discovery of the drum disposal area resulted in the issuance of a Unilateral Administrative Order by the U.S. Environmental Protection Agency calling for a phased investigation and removal of the drums and contaminated soil under the Comprehensive Environmental Response, Compesation, and Liability Act. The investigation was carried out in four phases including: (1) inventory of exposed drums and a surface geophysical survey of the drum disposal area; (2) historical records search; (3) drum sampling and characterization; and (4) excavation, removal, and on-site containment of drums and contaminated soil. Work on these phases was perfomred between August 1991 and June 1993. Unique aspects of this work included the excavation of buried, corroded drums from a remote area in rugged terrain; delineation and excavation of DNT-contaminated soil; and evaluation of an appropriate level of personal protective equipment for field work using field monitoring methods.
Remediation of DNT drum disposal area.
In 1991, an abandoned drum disposal area was discovered in a small ravine known as the Wash 3 tributary at the Apache Powder Superfund Site near Benson, Arizona. The 110-gallon steel drums were found to have been used to store 2,4- and 2,6-dinitrotoluene (DNT) that was purchased for experimental formulation of a composite explosive for the mining industry in the 1955 to early 1960's timeframe. The Arizona Department of Health Services has established a Health-Based Guidance Level for ingestion of 2,4-DNT at 2 milligrams per kilogram (mg/kg) and at 120 mg/kg for 2,6-DNT. Although the drums were mostly empty, small quantities of residual DNT were present at the time of disposal and were released to the soil from corroded drums.