U.S. airports are being required, under a new federal environmental rule, to comply with technology-based guidelines intended to limit the use of toxic pavement deicers and the discharge of hazardous aircraft deicing fluids. In developing the final rule, which took effect June 15, the U.S. Environmental Protection Agency (EPA) discarded initial proposals that, in part, would have limited the deicing of airplanes at airport gates and required expanded use of centralized deicing pads and glycol-collection trucks. Organizations representing airports, airlines and airline pilots had opposed those proposals, citing safety concerns, among other issues.
Although EPA has jurisdiction over environmental concerns, the Federal Aviation Administration (FAA) is responsible for regulating and providing guidance on safely conducting these activities.
The new regulation,1 following a three-year analysis of public comments and data, addresses issues intended to improve the management of wastewater discharges from airport deicing operations — typically stormwater polluted by deicing fluid reaching nearby surface waters or exceeding the capacity of publicly owned water-treatment works. The focus of EPA’s rule making was the application of deicing and anti-icing fluids to aircraft, and the application of solid and liquid deicing products to airport movement-area pavement.
The regulation implements effluent-limitations guidelines and source performance standards under the Clean Water Act, according to the environmental agency.2,3 “The requirements generally apply to wastewater associated with the deicing of airfield pavement at primary airports,” EPA said. “The rule requires all such airports to comply with requirements based on substitution of less toxic pavement deicers that do not contain urea. The rule also establishes [new source performance standards] for wastewater discharges associated with aircraft deicing for a subset of new airports. These airports must also meet requirements based on collection of deicing fluid and treatment of the collected fluid.”
The broader initial proposal was criticized, in part, by aviation industry commenters as likely to increase risk during winter flight operations and as an overreach of EPA authority. Some argued that U.S. airports are too diverse for national rules to be practicable.
EPA estimated that the aviation industry’s compliance with the final rule annually would cost $3.5 million to reduce the discharge of deicing-related pollutants by 16 million pounds (7.3 million kg). “The final rule is expected to decrease [chemical oxygen depletion] discharges associated with airport runway deicing and anti-icing activities by approximately 12.0 million pounds [5.4 million kg] per year,” EPA said. “The rule is also estimated to reduce ammonia discharges by 4.4 million pounds [2.0 million kg, disregarding any future airport construction].”
Even those who objected to EPA’s entire regulation typically agreed in their public docket comments that mitigating risks of accidents during flight operations and mitigating environmental harm near airports are both important societal goals. Some airports presented data documenting minimal local environmental effects from deicing fluids because of existing programs, natural dilution of wastewater or other reasons.
“Airports in the United States discharge deicing wastewater to a wide variety of water body types, including streams, rivers, lakes and estuaries,” EPA said. “Many airports discharge deicing wastewater to small streams with limited waste dilution and assimilation capacities. Impacts from deicing wastewater discharges have been documented in a variety of surface waters adjacent to or downstream of a number of airports in the United States. Some locations experienced acute impact events, whereas other locations have experienced chronically degraded conditions. … Documented human use impacts include contamination of surface drinking water sources, contamination of groundwater drinking water sources, degraded surface water aesthetics due to noxious odors and discolored water in residential areas and parklands, and degradation of fisheries.” Other observed impacts to surface waters include reductions in dissolved oxygen, fish kills and reduced organism abundance and species diversity, the agency said.
Deicing for Safe Taxiing
The controversy over restricting the use of aircraft deicing fluid at airport gates started with EPA’s proposal to exempt the associated wastewater from new collection and treatment requirements by limiting deicing for safe taxiing to the use of a maximum of 25 gal (95 L) of fluid. “Deicing for safe taxiing means the application of [aircraft deicing fluid] necessary to remove snow or ice to prevent damage to a taxiing aircraft,” EPA said, and includes removal of frost, ice and snow from various critical components such as windshields and engine intake ducts or heavy snow before taxiing the aircraft to a deicing pad for full deicing/anti-icing.
“This [proposal] was intended to apply to airports with [centralized deicing pads], and to prohibit conducting complete deicing of an aircraft at a terminal area without a collection system, instead of using the deicing pad,” the agency said. EPA said that public comments alleged that the agency had failed to consider wide differences among airports in winter conditions and factors such as the application flexibility required by cargo aircraft during layovers of more than 24 hours.
The Air Line Pilots Association, International (ALPA) said in 2010, “Several factors must be taken into account to properly conduct deicing operations of an aircraft preparing for takeoff. These include differences in the type, rate and temperature of precipitation, all of which may increase the need for [aircraft deicing fluid]; the length, width and applicable surfaces of the most demanding airplane; the amount of holdover time required for an aircraft to safely taxi and be in a position for takeoff following the aircraft’s initial or subsequent deicing; and the proficiency of ground personnel to properly perform assigned deicing operations. … Poor deicing technique by applying [fluids] to non-critical surfaces could result in consuming the fixed 25 gal of [fluid as proposed] before it is applied to the correct surfaces. … We believe that [the threat of an EPA penalty or violation] could result in circumstances where ground personnel may not complete the deicing to the FAA standard, potentially jeopardizing the safety of the flight.” ALPA added that a proposed requirement for glycol-collection vehicle operators to attend all deicing activities (except for pre-taxi deicing) likely would degrade their situational awareness and increase the risk of apron-area collisions.
The Massachusetts Port Authority was among commenters that noted that “EPA is proposing to assume the responsibility of requiring airlines to use a specific deicing technology [contrary to FAA policy] and to quantify the amount of deicing that is adequate (with its proposed 25-gal allowance for taxiing). Thus, the proposed rule would inappropriately extend EPA’s regulatory reach from pollution reduction to aviation safety matters.”
Airlines for America noted that EPA’s restriction on deicing for safe taxiing “would effectively eliminate any aircraft departures which cannot operate because 25 gal of [fluid] is inadequate to clear engine intakes and other critical areas for safe taxiing. No airline would compromise safety, or suggest that its pilots-in-command compromise flight safety by taxiing an inadequately deiced aircraft.”
EPA ultimately concurred that a number of these and related concerns were valid. “EPA agrees with the commenters, and therefore the final rule does not limit the amount of [aircraft deicing fluid] sprayed for the purposes of safe taxiing, nor does EPA require an airport to collect and treat [aircraft deicing fluid] applied for safe taxiing purposes,” the agency said in May.
Deicing Pad Realities
This announcement also explained the outcome of EPA’s original proposal to emphasize centralized deicing pads. As noted, in the final rule, the applicability of a new requirement was changed from new and existing airports to new airports only. “A [centralized deicing pad] is a paved area on an airfield built specifically for aircraft deicing operations,” EPA said. “EPA estimates that [these pads] allow airports to collect at least 60 percent of the available [aircraft deicing fluid].”
EPA noted some stakeholder concerns about using centralized deicing pads for all deicing operations because of safety problems and airfield traffic issues. ALPA, for example, said, “Our primary objective is to ensure that the aircraft has been prepared in the FAA-approved manner, that it remains clean of snow and ice, and that it is in a condition to complete a safe takeoff. If this goal is accomplished through the use of a [centralized deicing pad], the location of that facility must not interfere with the safety of airport and flight operations.”
In the case of Boston-Logan International Airport, for example, the Massachusetts Port Authority said, “If aircraft were required to taxi from the gate to a centralized deicing pad located in one part of the airport, then to a departure runway in another part of the airport, the number of runway crossings occurring during taxiing — and thus the number of potential runway incursions — would greatly increase. … [Another safety] reason to have pads at each set of runway ends is to minimize the time between deicing/anti-icing and departure. [Another] reason for locating a pad at each set of runway ends is to prevent pad use from interfering with runway use.” The FAA also advised EPA that at existing land-constrained airports, construction and operation of centralized deicing pads for all deicing operations would not be able to meet FAA design standards.
In the end, EPA said, “EPA has concluded that the lack of remaining available land, coupled with their existing layouts, has left these airports in a position where a [centralized deicing pad] conforming to FAA’s advisory circulars on deicing pad design (e.g., in a location that aircraft can travel to safely and efficiently to conduct deicing operations) cannot be constructed. … With respect to new airports, the use of [centralized deicing pads] does not present the space/land, safety or operational issues that would be raised in connection with the use of deicing pads at existing sources.”
EPA is responsible for addressing deicing discharges under protocols that recognize changing technology and the potential side effects of regulatory strategies. “[These] regulations address control of the wastewater discharges from deicing operations based on product substitution, wastewater collection practices used by airports, and treatment practices for the collected wastewater,” the agency said. “New source airports [i.e., future airports] within the scope of this rule are required to collect spent aircraft deicing fluid … and meet numerical discharge limits. Those airports and certain existing airports performing airfield pavement deicing are to use non-urea-containing deicers, or alternatively, meet a numeric effluent limitation for ammonia. The requirements are implemented in [Clean Water Act] discharge permits. … Currently, most airport deicing discharges are covered by a general permit issued by either EPA or … [a] state agency.”
Under the new regulatory scheme, U.S. airports annually using more than 100,000 gal (379,000 L) of glycol-based deicing chemicals and/or 100 tons (101,600 kg) or more of urea-containing deicers initially must monitor discharges for biochemical oxygen demand, chemical oxygen demand, ammonia and pH (acidity/alkalinity). The standards “reflect effluent reductions that are achievable based on the best available demonstrated control technology” for all categories of pollutants, EPA said.
“No single technology or [pollution prevention] approach is capable of collecting or eliminating all applied [fluid], as a portion of the fluid is designed to adhere to the aircraft until after takeoff, in order to ensure safe operations,” EPA said. “After considering other options, EPA selected site-specific aircraft deicing discharge controls as most feasible given the diversity of the affected U.S. airports. … There are limited instances where an airport in a warm climate that performs only defrosting and gets little to no precipitation may, in fact, not discharge any deicing materials.”
Introducing discharge controls means that the final rule’s provisions do not “establish effluent limitation guidelines … for aircraft deicing discharges, but instead, leave the determination of … requirements for each airport to the discretion of the [federal/state] permit writer on a case-by-case, ‘best professional judgment’ basis based on site-specific conditions [that consider localized operational constraints (e.g., traffic patterns), land availability, safety considerations, and potential impacts to flight schedules],” EPA said.
“In addition to applying the proposed departure threshold, EPA is making [the standards’] collection requirements for [aircraft deicing fluids] applicable based on whether the airport is located within specific colder climatic zones … as documented by the National Oceanic and Atmospheric Administration (NOAA).”
Airlines for America had said in 2010 that EPA’s original proposal for regulating airport deicing would violate basic federal aviation policy “by failing to acknowledge that safety considerations must override all other considerations and must be the final decision criterion for all deicing-related operational and design decisions by airlines and airports; [and] by relegating to a secondary consideration the federal mandate and industry commitment to the safety of the flying public in the context of the most challenging ground icing conditions. … Safety is the ‘gatekeeper’ issue whenever a project, initiative or regulation has the potential to affect ground and/or air operations — if safety would be compromised, the project or initiative fails by definition. Safety is even more central in the context of this rule making because, as EPA recognizes, safety is the sole purpose and aim of aircraft and airfield deicing and anti-icing activities.”
In summary, faced with these aviation safety–related objections and arguments about factors such as flight delays and space/operational constraints of existing airports, “EPA found that its ‘model facility’ approach was not a suitable substitute for a detailed analysis of the site constraints at each airport,” the agency said. “For example, a permit authority may need to evaluate existing traffic patterns at an airport, not only of the aircraft, but also of the service vehicles to determine if additional [glycol] collection vehicles would lead to unacceptable safety concerns.”
- EPA. “Effluent Limitations Guidelines and New Source Performance Standards for the Airport Deicing Category; Final Rule.” In Federal Register, Volume 77, No. 95, Rules and Regulations, p. 29168, May 16, 2012.
- These standards and guidelines “will be incorporated into National Pollutant Discharge Elimination System … permits issued by the [federal/state] permitting authority,” EPA said.
- The official title is Federal Water Pollution Control Act Amendments of 1972.