Airport Deicing Rule

• Who is covered by the regulations?
• What is the purpose of the regulations?
• Regulations
• Compliance Options
• Best Practices
• More Resources

This section provides information about rules that regulate effluent from aircraft deicing. The final rule was published on May 16, 2012.

Who is covered by the regulations?

• All airports that conduct airfield pavement deicing operations, and have 1,000 or more annual jet departures or
• New airports in designated cold weather locations that perform aircraft deicing and have 10,000 or more total annual departures

What is the purpose of the regulations?

Aircraft deicing fluids contain high concentrations of antifreeze chemicals, typically ethylene or propylene glycol, plus lower concentrations of corrosion inhibitors and other additives. The proposed regulations are intended to mitigate the effects on water quality that can result from the rapid release of large quantities of untreated deicing fluid. Deicing a single plane can involve anywhere from 50 gallons of deicing fluids (for a small plane), up to 2,000 gallons for a large plane with heavy ice accumulation. When these fluids run off into the environment, the chemicals in the fluids can pollute surface water and degrade property.

Aircraft deicing fluids contain high concentrations of antifreeze chemicals, typically ethylene or propylene glycol, plus lower concentrations of corrosion inhibitors and other additives. In addition to direct toxic effects, the fluids can stimulate the growth of microorganisms that deplete water of dissolved oxygen, leading to the death of fish and other organisms. Older formulations contain urea, which can be even more effective than glycols in stimulating excessively rapid growth.

The regulations are intended to mitigate the effects on water quality that can result from the rapid release of large quantities of untreated deicing fluid.

Regulations

On May 16, 2012,EPA has issued Effluent Limitations Guidelines and New Source Performance Standards for the Airport Deicing Category. These regulations are codified at 40 CFR Part 449.

The requirements generally apply to wastewater associated with the deicing of airfield pavement at primary airports. The rule also establishes new source performance standards for wastewater discharges associated with aircraft deicing for a subset of new airports. In general. airport deicing regulations require:

• Existing and new primary airports with 1,000 or more annual jet departures ("non-propeller aircraft") that generate wastewater associated with airfield pavement deicing are to use non-urea-containing deicers, or alternatively, meet a numeric effluent limitation for ammonia.
• New airports with 10,000 annual departures located in certain cold climate zones are required to collect 60 percent of aircraft deicing fluid after deicing. Airports that discharge the collected aircraft deicing fluid directly to waters of the U.S. must also meet numeric discharge requirements for chemical oxygen demand.

Note that the rule does not establish requirements for aircraft deicing discharges at existing airports. EPA assumed that such requirements will continue to be established in general stormwater permits, or for individual stormwater permits on a site-specific basis.

Compliance Options

In developing the aircraft deicing rule, EPA considered a variety of options that are now in use in airports across the U.S.:

• Using deicing pads with a dedicated drainage system
• Using existing drainage systems (for deicing operations carried out at passenger gates and cargo ramps, and in aircraft parking areas)
• Directing discharge into "grassed swales" that allow runoff to seep into the ground, rather than being discharged into a stream
• Installing mechanisms to plug drain lines temporarily to capture runoff when it contains deicing fluids, so that it can be pumped out and/or treated prior to release
• Using glycol recovery vehicles to vacuum fluids from pavement before they enter the drainage system

Options for treating the captured wastewater include:

• Separation systems that recover glycol for recycling (i.e. that nondestructively remove the glycol from the water)
• Aerated lagoons (the process used in most sewage treatment plants)
• Anaerobic fluidized bed (AFB) digesters
• Sufficient land area, or constructed wetlands, that hold the runoff for enough time to allow natural processes to decompose the fluids without overloading the capacity of the ecosystem receiving the runoff

EPA expects that new airports that must meet the 60% capture limit will require:

• Capture technology that performs at a level comparable to existing systems that use centralized deicing pads
• Treatment technology that performs at a level comparable to existing systems that use AFB technology

The rule does not specify what technology is to be used, as long as the capture and treatment performance falls within the limits. Airports are free to adopt whatever technology best suits their individual circumstances.

Best Practices

Several types of products, such as potassium acetate, sodium formate, and sodium acetate, are available as alternatives to pavement deicers containing urea. The results from EPA's airport questionnaire reported that 83 percent of primary airports use airfield pavement deicers that do not contain urea. The most widely used substitute product, potassium acetate, accounts for 63 percent (by weight) of the annual airfield pavement deicer usage in the US.

Pollution prevention measures should be considered among the options available for complying with the aircraft deicing rule. Many facilities are already using various combinations of the following suggestions to minimize the impacts of deicing:

• Avoid unnecessary aircraft deicing

  When deicing fluid is released into a stream or wetland, it knocks nutrient flow out of balance. Simple organisms, low on the food chain, can take advantage of a sudden influx of available nutrients faster than more complex species. The fast-growing organisms can use up the oxygen normally available to fish and vegetation, which can lead to die off and degradation of land quality. Substituting one available nutrient for another will not mitigate that effect.

• Minimize excess usage and overspray by controlling application rate and spray pattern
• Use a more dilute solution when conditions permit
• Remove ice mechanically (may be feasible for small aircraft, when conditions do not require protection against subsequent icing)
• Use a forced air system (can be used in place of fluid for light frost, or in conjunction with fluid to minimize fluid use)

Another option is the use of alternative fluids, including fluids available from biobased sources (i.e. chemicals produced through recent biological activity, rather than being derived from petroleum). An example is a glycol, 1,3-propanediol, derived from cornstarch. In terms of best environmental practices, note that environmental benefits of that compound would depend on the life-cycle impacts involved in producing the material from corn, as compared to the impacts of producing propylene glycol from petroleum. Both biobased and petroleum-based fluids have about the same impact when released into the environment.

More Resources

Airport Deicing Effluent Guidelines. This EPA webpage provides a summary of the rule, plus links to background and related documents.