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Toxics Release Inventory (TRI) Program

Descriptions of TRI Data Terms: Text Version

This webpage explains the terms that EPA uses to describe toxic chemical releases and other waste management quantities reported under the TRI Program, and indicates where on the TRI Form R they are reported. 

Please note that the descriptions on this webpage have been simplified for educational purposes and should not be relied upon to determine a facility’s TRI reporting obligations. See the TRI Reporting Forms and Instructions for extensive reporting guidance.

See the interactive version of the text content on this page

On-site Releases and Other Waste Management

Air Releases (On Site)

Air releases include both fugitive air emissions and point source air emissions. Fugitive air emissions are all releases to air that don’t occur through a confined air stream. Fugitive emissions include equipment leaks, releases from building ventilation systems and evaporative losses from surface impoundments and spills. Point source air emissions, also called stack emissions, are releases to air that occur through confined air streams, such as stacks, ducts or pipes.

Reported in TRI Form R Sections:

  • 5.1: Fugitive or non-point air emissions
  • 5.2: Stack or point air emissions

Surface Water Discharges (On Site)

Surface water discharges include discharges to streams, rivers, lakes, oceans and other bodies of water. This includes discharges from contained sources, such as industrial process outflow pipes or open trenches. Facilities must identify the name of each water body into which the TRI chemical is being discharged. Releases of TRI chemicals due to runoff, including stormwater runoff, are also reportable in this category.

Reported in TRI Form R Section:

  • 5.3: Discharges to receiving streams or water bodies

Land Releases (On Site)

Land releases include disposal of toxic chemicals in landfills (in which wastes are buried) or surface impoundments (which are uncovered holding areas used to volatize and/or settle waste materials), other land disposal methods (such as waste piles), and other releases to land (such as spills or leaks). Land releases also include injection into underground wells. An injection well is a device that places fluids deep underground into porous rock formations, such as sandstone or limestone, or into or below the shallow soil layer. 

Reported in TRI Form R Sections:

  • 5.4.1: Underground injection on site to Class I Wells
  • 5.4.2: Underground injection on site to Class II-V Wells
  • 5.5.1A: RCRA Subtitle C landfills
  • 5.5.1B: Other landfills
  • 5.5.2: Land treatment/application farming
  • 5.5.3A: RCRA Subtitle C surface impoundments
  • 5.5.3B: Other surface impoundments
  • 5.5.4: Other disposal

Recycling (On Site)

Recycling includes a variety of methods through which toxic chemicals in waste can be recovered, such as solvent recovery and metals recovery. To be reported as recycling under TRI, the chemicals or the waste containing the chemicals must undergo a recovery step prior to being used again, such as removing impurities from a solvent. The choice of the recycling method depends on the toxic chemical. Once they have been recycled, these chemicals may be reused at the facility or made available for use in commerce.

Reported in TRI Form R Section:

  • 8.4: Quantity recycled on site

Used for Energy Recovery (On Site)

A facility can report a toxic chemical as "used for energy recovery" if the chemical was combusted in an industrial furnace (including kilns) or boiler (as defined in the regulations) to generate heat or energy for use at the facility. This process can be used for toxic chemicals of significant heating value (>5000 BTUs) in wastes. Incineration of a chemical that is not of significant heating value or in a device that does not meet the regulatory definition of an industrial furnace or boiler is not considered to be used for energy recovery.

Reported in TRI Form R Section:

  • 8.2: Quantity used for energy recovery on site

Treatment (On Site)

On-site treatment includes a variety of methods through which toxic chemicals in waste may be treated, such as biological treatment, incineration, and chemical oxidation. These methods typically result in varying degrees of destruction of the toxic chemical. Facilities report the quantity of the toxic chemical destroyed in on-site waste treatment operations.

Reported in TRI Form R Section:

  • 8.6: Quantity Treated On Site

Off-site Transfers of Toxic Chemicals in Waste

An off-site transfer is the transfer of toxic chemicals in waste to a facility that is geographically or physically separate from the facility reporting under TRI. Chemicals reported to TRI as transferred are sent to off-site facilities for the purposes of recycling, energy recovery, treatment, or disposal. The amounts reported represent a movement of the chemical away from the reporting facility. Except for off-site transfers to disposal, these amounts do not necessarily represent entry of the chemical into the environment.

Reported in TRI Form R Sections:

  • 6.1: Discharges to Publicly Owned Treatment Works (POTWs)
  • 6.2: Transfers to Other Off-Site Locations

Transfers Off Site for Disposal

This category includes various methods of disposal, such as landfills, surface impoundments, and underground injection. Off-site transfers to disposal are also referred to as "off-site releases." 

Reported in TRI Form R Section:

  • 6.2: Transfers to Other Off-Site Locations

Transfers Off Site for Recycling

Off-site recycling includes a variety of methods through which toxic chemicals in waste can be recovered, such as solvent recovery and metals recovery. To be reported as off-site recycling, the chemicals or the waste containing the chemicals must undergo a recovery step prior to being used again, such as removing impurities from a solvent. The choice of the recycling method depends on the toxic chemical. Once they have been recycled, these chemicals may be returned to the originating facility for further processing or made available for use in commerce. Facilities report the quantity of the toxic chemical that left the facility boundary for recycling.

Reported in TRI Form R Section:

  • 6.2: Transfers to Other Off-Site Locations

Transfers Off Site for Energy Recovery

A facility can report a toxic chemical as "used for energy recovery" if the chemical was combusted in an industrial furnace (including kilns) or boiler (as defined in the regulations) to generate heat or energy for use at the facility. This process can be used for toxic chemicals of significant heating value (>5000 BTUs) in wastes. Incineration of a chemical that is not of significant heating value or in a device that does not meet the regulatory definition of an industrial furnace or boiler is not considered to be used for energy recovery. Facilities report the quantity of the toxic chemical that left the facility boundary for energy recovery, not the amount combusted at the off-site location.

Reported in TRI Form R Section:

  • 6.2: Transfers to Other Off-site Locations 

Transfers Off Site for Treatment (Excluding POTWs)

Off-site treatment includes a variety of methods through which toxic chemicals in waste may be treated, such as biological treatment, incineration, and chemical oxidation. These methods typically result in varying degrees of destruction of the toxic chemical. Facilities report the quantity of the toxic chemical that left the facility boundary for treatment, not the amount that was destroyed at the off-site location(s).

Reported in TRI Form R Section:

  • 6.2: Transfers to Other Off-site Locations 

Off-site Transfers to Publicly Owned Treatment Works (POTWs)

A POTW is a wastewater treatment facility that is owned by a state or municipality. Wastewaters from facilities reporting under TRI are transferred through pipes or sewers to a POTW. Treatment or removal of a chemical from the wastewater depends upon the nature of the chemical, as well as the treatment methods present at the POTW. Not all TRI chemicals can be treated or removed by a POTW. Some chemicals, such as metals, may be removed, but are not destroyed and may be disposed of in landfills or discharged to receiving waters. Transfers to POTWs of metals and other chemicals that are not destroyed are categorized as off-site releases.

Reported in TRI Form R Section:

  • 6.1: Discharges to Publicly Owned Treatment Works (POTWs)

Other Commonly Used Terms

Total On- and Off-site Disposal or Other Releases

The sum of total on-site disposal and other releases and total off-site disposal or other releases (also known as transfers off-site for disposal).

  • Reported in TRI Form R Section 5 and portions of Section 6

Total On-site Disposal or Other Releases

On-site disposal or other releases include emissions to the air, discharges to bodies of water, and disposal at the facility to land.

  • Reported in TRI Form R Section 5