MEMORANDUM 

TO: Mr. Brian D’Amico, USEPA/EAD 

FROM: Ms. Mary Willett and Cal Franz, ERG 

DATE: January 23, 2012 

SUBJECT: NSPS Feasibility – ADF Collection and Treatment Requirements 

Background 

Under the New Source Performance Standards (NSPS) for the Airport Deicing Category, EPA is 

establishing a standard of 60 percent collection of available aircraft deicing fluid (ADF) and 

treating that waste to a numeric limit for the collected ADF. Available ADF is defined by EPA 

as 75 percent of the sprayed deicing fluid and 10 percent of the sprayed anti-icing fluid, 

excluding sprayed fluids used for defrosting or deicing for safe taxiing. EPA based the NSPS 

collection requirement on the use of centralized deicing pads (CDPs) and the numeric limit on 

anaerobic fluidized bed (AFB) treatment. CDPs are defined by EPA as a facility on an airfield 

designed for aircraft deicing operations, constructed with a drainage system separate (or one that 

can be made separate) from the airport main storm drain system, and where the separate drainage 

system is connected to a wastewater storage facility. 

This memorandum summarizes EPA’s assessment that the NSPS requirements for ADF 

collection and treatment, while they may not be technologically available nationwide for some 

existing airports based on current information, are nevertheless available and feasible for new 

airports. 

CDP Comments 

The focus of the comments received on CDPs related to their use at existing airports. While 

these comments primarily related to the proposed BAT and not NSPS, EPA similarly considered 

each of these concerns with respect to new airports. 

Commenters raised multiple concerns about the technology basis for the proposed 60 percent 

collection requirement at existing airports: centralized deicing pads. First, they raised concerns 

that centralized deicing pads are not feasible at all locations because of lack of space. Second, 

commenters raised concerns that using CDPs would cause traffic and/or safety problems and 

would lead to delays. Finally, they raised concerns about the EPA’s proposal to require all 

deicing to be performed at CDPs. In particular, they noted that deicing applied for safe taxiing 

should not be subject to this requirement. 

FAA also provided EPA with comments, which reiterated some of the issues raised by public 

commenters regarding the installation of centralized deicing facilities at existing airports. 
Memorandum 

23 January 2012 

Page 2 

Further, FAA is concerned that for those land-constrained airports, construction and operation of 

centralized deicing pads would not be able to meet FAA design standards. FAA raised concern 

about safety and efficiency with a provision that would exclusively require deicing pads to be 

used, noting that delays are extremely costly to the nation's productivity, economy, businesses, 

and the traveling public. 

After considering these comments and reviewing the information in its record, EPA has 

concluded that while some existing airports can and do employ CDPs safely and efficiently for 

deicing of some of their aircraft, the lack of available land, coupled with their existing layouts, 

has left some other existing airports in a position where installation of an airport-wide system of 

centralized deicing pads, intended for all deicing activities, and 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) may be infeasible, see section V.B.2 in the preamble 

for further discussion. These concerns are associated with the technologies used for spent ADF 

collection, as these technologies must be deployed in areas with aircraft activity. EPA is not 

aware of such constraints regarding treatment systems and storage/equalization associated with 

meeting the numeric discharge limit. These may be situated anywhere on the airport grounds as 

there is no need for constructing storage/equalization and treatment facilities near the deicing 

areas. 

EPA also made modifications to the definition of available ADF which addresses these 

comments. In order to ensure safe aircraft operations, the final rule excludes ADF that is applied 

for safe taxiing. Therefore, the deicing that an airport may perform for this purpose is not 

subject to the NSPS collection or treatment requirements of this rule. Moreover, EPA received 

comments that defrosting activities, in many instances, will not result in any ADF that is 

available for collection. Therefore EPA is also exempting ADF sprayed for defrosting operations 

from the final rule requirements. 

NSPS Feasibility 

Having excluded ADF applied for safe taxiing and defrosting, EPA in consultation with FAA, 

finds that the concerns raised about safety, space, and operational constraints for CDPs that may 

be present at existing airports would not similarly apply to new airports. When designing a new 

airport, an airport authority has the ability to purchase enough land and design the airport layout 

in a fashion that would be able to avoid the logistical issues that arise when retrofitting a CDP, 

and no data was provided to indicate otherwise. Furthermore, as described above, EPA has made 

allowances in the final rule for deicing performed for safe taxiing and defrosting which resolve 

the potential safety issues associated with the 100 percent CDP requirement for all deicing 

activities. 

Many existing airports utilize CDPs. Based on airport questionnaire responses, deicing pads are 

used at 34 airports for at least a portion of their flights, ranging from large to non-hub airports. 

One of the airports is Denver International (DIA). Denver, the only new airport to open in the 

last 25 years that meets the applicability of the ELG, installed and uses deicing pads for all of 
Memorandum 

23 January 2012 

Page 3 

their flights1. During EPA’s site visit to DIA on November 8, 2005, airport personnel indicated 

that all deicing is done on their CDPs, with the exception of low-level gate deicing (up to 25 

undiluted gallons of ADF) to allow for safe plane movement. In 2011, EPA was told that, for a 

while, United Airlines discontinued the use of pads in favor of gate deicing. During this time, 

Denver experienced a whole host of complaints. Denver cited the mess at the gates and odor 

problems in gate areas and basements. As a result of these complaints, all deicing (except low 

level) is once again done on CDPs. In addition, Denver indicated that when fully staffed, it 

processes planes through the deicing pad more quickly than the available capacity at their 

runways. 

Finally, FAA concurs with EPA’s conclusion that new airports can be designed to minimize 

space and logistical constraints that may be identified for retrofits at existing airports. Further, 

they also noted that when designed appropriately, pad usage actually improves traffic flow and 

reduces delays. 

Summary 

EPA has concluded that CDP technology is technologically available and demonstrated at new 

source airports for the collection of ADF-contaminated wastewater and that successful siting and 

sizing of deicing pads is achievable when planners take these CDPs into account during the 

design phase of new airport construction. In addition, the only available evidence indicates that 

rather than leading to delays, use of such CDPs in fact improves traffic flow and reduces delays. 

References 

USEPA. 2008. Airline Detailed Questionnaire Database. U.S. Environmental Protection 

Agency/Office of Water. Washington, D.C. DCN AD00938. 

USEPA. 2008. Airport Questionnaire Database. U.S. Environmental Protection Agency/Office 

of Water. Washington, D.C. DCN AD00927. 

USEPA. 2007. Final Engineering Site Visit Report for Denver International Airport. U.S. 

Environmental Protection Agency/Office of Water. Washington, D.C. (November 4). DCN 

AD00779. 

Denver International Airport: Information on Selected Financial Issues. General Accounting 

Office. (Letter Report, 09/18/95, GAO/AIMD-95-230). 

www.colorado.edu/libraries/govpub/dia.htm

 

1

 DIA is operated by the City and County of Denver Department of Aviation and is a municipal airport facility 

serving the Denver, Colorado metropolitan area. The airport opened on February 28, 1995 and includes 4 northsouth and 2 east-west runways, for a total of 6 runways. The airport has 89 gates and associated taxiways, aircraft 

parking aprons; three airside concourses; and passenger and cargo terminals. The airport was designed with a 

centralized deicing system comprised of four CDPs that are used for passenger aircraft, and the airport has since 

added a fifth pad. The airport also has general aviation and cargo ramps and a CDP which is occasionally used by 

cargo aircraft. Each of the passenger aircraft CDPs feed high concentration ADF stormwater (greater than 1 percent 

glycol) to on-site storage tanks located at the airport’s glycol recycling plant.