Open burn (OB) and open detonation (OD) operations are conducted to destroy excess, obsolete, or unserviceable (EOU) munitions and energetic materials. In OB operations, energetics or munitions are destroyed by self-sustained combustion, which is ignited by an external source, such as flame, heat, or a detonation wave. In this case, an auxilliary fuel may be added to initiate and sustain the combustion of materials. In OD operations, detonatable explosives and munitions are destroyed by a detonation, which is generally initiated by the detonation of an energetic charge.
In the past, OB/OD generally occured in the surface of the land or in pits. Recently, burn trays and blast boxes are being used in an attempt to control and contain the destruction of energetics and resulting contaminants/emissions. In detonation processes the blast box may be below grade and covered with soil to further minimize the release of emissions.
OB/OD operations can destroy many types of explosives, pyrotechnics, and propellants. OB areas must be able to withstand accidental detonation of any or all energetics being destroyed, unless the operating OB technicians recognize that the characteristics of the materials involved are such that orderly burning without detonation can be ensured. Personnel with this type of knowledge must be consulted before any attempt is made at OB disposal, especially if primary explosives are present in any quantity.
OB and OD can be initiated either by electric, burning, or energetic charge ignition systems. In general, electric systems are preferable because they provide better control over the timing of the initiation. In an electric system, electric current heats a bridge wire, which ignites a primary explosive or pyrotechnic, which, in turn, ignites or detonates the material slated to be burned or detonated. If necessary, safety fuses, which consists of propellants wrapped in plastic weather stripping, are used to initiate the burn or detonation. In some cases, scrap energetics or dried activated carbon from pink/red water treatment may be used as the initiation charge.
Typical Open Burning Pan and Cage
OB/OD can be used to destroy excess, obsolete, or unserviceable (EOU) munitions, components, energetic materials, as well as, media contaminated with energetics.
The following factors may limit the applicability and effectiveness of the process:
Minimum distance requirements for safety purposes mean substantial space is required for open processes.
OB/OD operations emissions are difficult to sufficiently capture for treatment and may not be permitted in areas with emissions limitations, although subsurface processes minimize emission release.
In open OB/OD operations, prevailing winds must carry sparks, flame, smoke, and toxic fumes away from neighboring facilities. OB/OD operations are never conducted during sand, snow, or electrical storms strong enough to produce static electricity, which might cause premature detonation.
OB/OD requires a RCRA Subpart X permit.
In addition, with growing OB/OD restriction, DOD's ability to treat energetic wastes is diminishing and energetics disposal, through OB/OD, may be eliminated.
Specific data required to evaluate the potential use of OB/OD operations include:
- Location plan for proposed OB/OD operations showing adjacent land uses and safety buffer zone.
- Emissions requirements for the geographic area of the OB/OD operation.
Several federal agencies are pursuing new technologies in this area including:
- DOE's molten salt technology,
- U.S. Army Construction Engineering Research Laboratory's (CERL) pyrolysis of energetic materials,
- U.S. Army Research Laboratory's supercritical fluid technology for nitramine recovery,
- U.S. Army Research and Development Engineering Center's (ARDEC) single- and multi-base propellant recovery technologies,
- Naval Surface Warfare Center (NSWC) Indian Head Division's supercritical fluid propellant extraction process,
Armstrong Laboratory's hydrothermal oxidation for propellant destruction, and
- Holston Army Amunition Plant's (AAP) recovery of waste explosives.