Subpart X Units

Types of Thermal Units Included Under Subpart X

Open Burning and Open Detonation Units

Description: Many waste propellants, explosives, and pyrotechnics (PEP), and munitions items are unsafe to treat by conventional methods of hazardous waste management. Open burning and open detonation (OB/OD) remain the primary methods of treatment for these wastes. Currently, research is being conducted to develop alternative methods of treatment for PEP wastes. New technologies, such as enclosed detonation chambers, are likely to become more widely available in the next several years. Some of these new technologies may qualify for permitting under Subpart X.

Open Burning: Physical Process and Description

Description: Open burning (OB) is used primarily to destroy propellants, and is generally conducted on engineered structures such as concrete pads, or metal pans to avoid contact with the soil surface. Such structures may range in size from 3 to 5 feet wide by 5 to 20 feet long, and are 1 to 2 feet deep.

Open Detonation Unit: Physical and Process Description

Description: Open detonation (OD) is used primarily to treat munition items. OD typically is conducted in pits or trenches below ground to minimize the ejection of treatment residue, although surface detonations are performed under certain circumstances.

Enclosed Treatment Units

Description: In recent years, DOD has encouraged the use of controlled thermal treatment units for the destruction of pyrotechnics, small arms ammunition and fireworks. Examples of enclosed thermal treatment units include the Donovan Blast Chamber, the Blast Containment Structure and the Hurd Burn Units.

Donovan Blast Chamber

Description: The Donovan Blast Chamber is used to perform controlled thermal treatment of PEP in a room-size blast chamber.

Blast Containment Structure

Description: The Army Corps of Engineers, Engineering and Support Center in Huntsville, Alabama, has developed a blast containment structure which is designed to capture all significant blast pressures for a total NEW of up to six pounds of TNT.

Hurd Burn Units

Description: The unit consists of a quarter-inch thick steel, enclosed cylindrical box equipped with a hinged door on one end. The cylinder or barrel is mounted on a movable trailer which may be positioned on a concrete pad when in operation. The fuel source for the unit is a pair of propane tanks.

Confined Burn Facility

Description: The U.S. Navy at Indian Head has designed a Confined Burn Facility (CBF) that uses a batch-feed chamber. Upon ignition of the wastes in the chamber, the hot gases that are generated are quenched with water and stored in a containment reservoir for subsequent scrubbing and treatment at a slow continuous rate before discharge.

Carbon and Catalyst Regeneration Units

Description: Carbon and catalyst regeneration units include both controlled-flame and non-flame devices. Since 1991, EPA has considered the regeneration or reactivation of spent carbon from a carbon absorption system, used in the treatment of a listed hazardous waste or used to capture emissions from a listed hazardous waste, to be thermal treatment under the interim status provisions of RCRA.

Thermal Desorption Units

Description: As outlined in a June 12, 1998, Policy Memo, EPA regulations do not define “thermal desorber”, but the term generally applies to a unit which treats wastes thermally to extract contaminants (e.g., volatile organics) from a matrix.

Vitrification Units

Description: The development of vitrification technology has been promoted by the large volume of low-level and high level radioactive waste requiring treatment at U.S. Department of Energy (DOE) sites. Much of this waste includes RCRA hazardous constituents and is regulated as mixed waste.

Ex-Situ Vitrification

Description: The ex-situ vitrification process is a thermal treatment process that both oxidizes and vitrifies wastes. It can treat wastes in the form of solids or as slurries. Typically waste and fuel are mixed in a pre-combustor before being transferred to a combustion chamber.

In-Situ Vitrification

Description: In-situ vitrification earth-melting technology was developed by Battelle Memorial Institute during the 1980s for DOE and is now commercially available as Geosafe Corporation’s GeoMeltTM technology.

Rotary Metal Parts Treatment Unit

Description: Rotary metal parts treatment (RMPT) is used in the decontamination of empty projectile and mortar shells. The RMPT consists of a cylindrical structure rotating at a prescribed speed inside a cylindrical furnace.

Types of Mechanical Units Included Under Subpart X

Shredder Units

Description: Shredders typically are used to make waste more amenable to subsequent treatment in other units, such as thermal desorbers, regeneration units, or incinerators, through reduction in size, and blending. Shredders may be regulated under Subpart X based on the material managed.

Filter Press Units

Description: Filter presses are used to separate solids from fluids under pressure. The most basic type of filter press is the plate-and-frame press.

Drum Crushers

Description: Drum crusher units that are eligible to be permitted under Subpart X handle containers of hazardous wastes. Typically, a can or drum crusher handles one container at a time.

Drum Washer

Description: Commercial drum washing systems are available from several manufacturers. These units are regulated as Subpart X units if the units are handling non-RCRA empty drums. The definition of RCRA empty container is provided in 40 CFR §261.7.

Mercury Bulb Crushers

Description: Fluorescent lamps are widely used in businesses, as they provide an energy-efficient source of lighting. The commercial and industrial sectors dominate usage of fluorescent lamps, accounting for over 90 percent of total usage.