MEMORANDUM 

TO: Brian D’Amico, EPA/EAD 

FROM: Mary Willett, ERG 

DATE: June 30, 2009 

SUBJECT: Evaluation of Proposed Compliance Alternative Ammonia Limitations with 

respect to Airport Deicing Stormwater Typical Ammonia Discharges 

Purpose 

The purpose of this memorandum is to compare the proposed compliance alternative ammonia 

limitation and standard for airport deicing operations to airport deicing stormwater discharges of 

ammonia at airports that use urea-based airfield deicing chemicals. 

Basis of EPA’s Proposed BAT for Airfield Deicing 

As part of the proposed rule, EPA wants to reduce discharges associated with the use of ureabased airfield deicing chemicals. As a result, EPA proposed BAT for airfield deicing to be 

product substitution and required an airport to certify (in the absence of compliance monitoring) 

that it is not using urea-based airfield deicing fluids. However, EPA also proposed a compliance 

alternative that would allow an airport to choose to meet an alternative ammonia limitation rather 

than provide a certification.1

 Because EPA estimated costs for the collection and treatment of 

airfield stormwaters and found the costs to be prohibitively high for most airports and because 

airfield deicing wastewater monitoring is extremely complex, EPA anticipates that airports 

subject to the proposed rule would chose to replace urea-based airfield deicing chemicals with a 

non-urea product and simply certify-- thus eliminating the necessity of monitoring and 

complying with the proposed compliance alternative ammonia discharge limitation. 

Basis of EPA’s Proposed Compliance Alternative Ammonia Discharge Limitation 

Because the proposed BAT for airfield deicing is product substitution, any compliance 

alternative ammonia limit would appropriately reflect non-use of urea. However, EPA also 

proposed a COD limit that would apply to all airport deicing stormwater discharges based on the 

long-term treatment performance data provided by Albany International Airport (ALB) which 

characterizes the treatment of deicing stormwaters through an Anaerobic Fluidized Bed (AFB) 

treatment system. A by-product of this treatment process is ammonia generation. As a result, 

the Agency evaluated ammonia concentrations resulting from the ALB wastewater treatment 

system and found that AFB discharges may have higher ammonia concentrations than 

background ammonia levels found in airfield runoff at airports without urea. As a result, EPA 

 

1

 Ammonia is a breakdown product of urea-based deicing fluids 
Memorandum 

June 30, 2009 

Page 2 

based its compliance alternative ammonia as N limitation on discharge concentrations from the 

AFB wastewater treatment system. See Table 1. 

Table 1. EPA’s Proposed BAT Compliance Alternative Ammonia as N Limitation and 

Standard 

Pollutant Daily Maximum (mg/L) 

Ammonia as N 14.7 

Using ammonia concentrations from the ALB effluent results in a proposed compliance 

alternative ammonia limitation which is higher than airfield runoff ammonia concentrations 

where no urea-based deicers are used. However, as described in more detail below, EPA 

concludes that the proposed compliance alternative limitation is lower than airfield runoff 

ammonia concentrations where urea-based deicers are used. 

Typical Ammonia Concentrations in Airport Deicing Stormwaters from Airports That Use 

Urea-Based Airfield Deicing Chemicals 

To evaluate whether airports which use urea-based airfield deicers in the absence of treatment 

are likely to discharge deicing stormwaters with ammonia as N (or ammonia) concentrations 

higher than the proposed ammonia- N compliance alternative limitation, ERG reviewed data 

from the following sources: 

 The Preliminary Data Study for the Airport Deicing Operations industry; 

 Several airport deicing stormwater studies; and 

 Industry-supplied data from Detroit Metropolitan Airport covering a timeframe 

prior to the airport’s discontinuation of urea airfield deicing chemical use. 

Table 2 presents a summary of the information identified representing typical ammonia as N (or 

ammonia) concentrations and concentration ranges from these sources. Review of Table 2 shows 

that in general deicing stormwater samples collected at airports with urea use reach ammonia as 

N (or ammonia) concentrations that exceed the proposed compliance alternative limitation (in 

some cases, by an order-of-magnitude). Of the 11 U.S. airports included in the table with either 

active urea use or suspected urea use, all but one showed maximum ammonia as N or ammonia 

concentrations above the proposed compliance alternative limitation, with maximum 

concentrations ranging from 1.1 mg/l to 171 mg/l. Additionally, studies for several non-U.S. 

airports in Canada and Europe using urea airfield deicing chemicals also demonstrate stormwater 

discharge ammonia concentrations above the proposed compliance alternative limitation, with 

maximum concentrations ranging from 17 mg/l to 124 mg/l. 

Typical Ammonia Concentrations in Airport Deicing Stormwaters from Airports that 

Discontinued Use of Urea-based Airfield Deicing Chemicals 

Both the Detroit Metropolitan Airport (DTW) and Pittsburgh International Airport (PIT) used 

urea deicers for airfield deicing in the past but have discontinued the practice. These airports 

provided long-term ammonia data for selected collection ponds and outfalls. Table 3 presents the 

range of ammonia concentrations measured in Ponds 4 and 6 at DTW since the airport stopped 
Memorandum 

June 30, 2009 

Page 3 

using urea. Table 4 presents the range of ammonia as N concentrations measured in runway 

related outfalls at the PIT since the airport stopped using urea. These data indicate that deicing 

stormwaters generated at airports that discontinue urea use typically have ammonia 

concentrations in their deicing stormwaters below 1 mg/L. None of the samples exceeded the 

proposed daily maximum compliance alternative limitation. 

Conclusion 

This analysis documents that EPA’s proposed compliance alternative ammonia-N limitation 

would likely be exceeded by airports using urea as a deicing chemical on their airfields in the 

absence of treatment; requiring airport’s subject to the regulation to modify airfield deicing urea 

use or to provide treatment. On the other hand, this analysis also documents that airports that 

have discontinued urea airfield deicing chemical would be able to comply with the proposed 

compliance alternative ammonia-N limitation. 
Memorandum 

June 30, 2009 Page 4 

Table 2. Typical Ammonia Concentrations in Airport Deicing Stormwaters 

Airport Source 

Indication of 

Urea Use 

Ammonia as N 

Concentration/Concentration 

Range (mg/L) Deicing Stormwater Descri

Greater Rockford 1 Yes ND (0.5) – 82 Airport submitted data (average was 24 mg/l), 19Albany 1 Yes 88 Contents of the small lagoon, EPA sampling, airp

concentration was an anomaly and they usually s

Albany 1 Yes 84 Composite of large lagoon and tank, EPA sampliBradley 1 Yes 1.1 Stormwater Outfall, EPA sampling, 1999 Chicago O’Hare 1 Not specified 0.2 – 50 PCS data pull, NW drainage, avg. effluent = 10.8 Chicago O’Hare 1 Not specified 0.2 – 50 PCS data pull, N drainage, avg. effluent = 11.2 mChicago O’Hare 1 Not specified 0.6 – 10 PCS data pull, NE drainage, avg. effluent = 3.4 mChicago O’Hare 1 Not specified 2.6 – 85 PCS data pull, SE drainage, avg. effluent = 35.1 mChicago O’Hare 1 Not specified 0.7 – 37.5 PCS data pull, SW drainage, avg. effluent = 8.28 Chicago O’Hare 1 Not specified 50 PCS data pull, drainage from deicing, 1997/1998 Louisville Standiford Field 

1 Not specified <0.03 – 171 Stormwater/deicing fluid runoff, PCS data pull, a

1997/1998 

Newcastle International Airport (United Kingdom) 

2 Yes 105.7 (ammonia) Measured at airport tributary, mean total ammoni

samples taken during freezing conditions 

Nine Canadian airports 3 Yes Max up to 124 mg/L (ammonia) Stormwater runoff Two European airports 3 Yes Max of 105 and 89.7 mg/L 

(ammonia) 

Stormwater runoff, mean values of 8.73 and 15.9 

Dayton International 4 Yes Max of 161 mg/L Dayton airport self-monitoring data reported for 

basin. 

Dayton International 5 Yes 11.3 – 13.7 Sampling results from the Dayton airport northw

spillway overflow, Ohio EPA sampling in Februa

Greater Cincinnati International 

7 Not specified 39.1 (ammonia) High value at Station 4. Downstream of box culv

runoff from the taxi lane and runway in the DHL 

BWI 8 Yes 32 (ammonia) Stormwater discharge pipe prior to discharge to K

sample was 32 mg/L; composite sample was 40 moccurred 2/26/93 during deicing event at the airp

General Mitchell International Airport 

9 Yes Max of 25.4 (ammonia) Sampled at Wilson Park Creek at the airport outf

1997 
Memorandum 

June 30, 2009 Page 5 

Table 2. Typical Ammonia Concentrations in Airport Deicing Stormwaters 

Airport Source 

Indication of 

Urea Use 

Ammonia as N 

Concentration/Concentration 

Range (mg/L) Deicing Stormwater Descri

General Mitchell International Airport 

10 Yes 16 (ammonia) Sampled at Wilson Park Creek at the airport outf

1997 

Western Pennsylvania airport (unnamed) 

11 Yes 53.3 Concentrations as high as 53.3 mg/L ammonia as 

urea reported in airport runoff samples 

Canadian airports 12 Not specified 0.11 – 17 (total ammonia) Chemical analyses for environmental samples (ruDetroit Metropolitan 14 Yes 0.01 – 13.7 (ammonia) Pond 3 concentration range for submitted data prDetroit Metropolitan 14 Yes 0.02 – 15.9 (ammonia) Pond 4 concentration range for submitted data prDetroit Metropolitan 14 Yes 0.01 – 26.9 (ammonia) Pond 6 concentration range for submitted data pr

Concentrations reported are for ammonia as N unless otherwise indicated. 
Memorandum 

June 30, 2009 Page 6 

Table 3. Detroit Metropolitan Airport Ammonia Concentrations for Post-Urea Ban Timefr

Airport Source Urea Use 

Ammonia Concentration 

Range (mg/L) Deicing Stormwater Descri

Detroit Metropolitan 14 No 0 – 1.5 (0.25 avg.) Pond 4 – flow from Pond 3E discharge to Frank a

runway/taxiway runoff) (# samples = 52) 

Detroit Metropolitan 14 No 0 – 2 (0.14 avg.) Pond 6 – runway/taxiway drainage from 3R/21L

4R/22L; 4L/22R; and 9R/27L (# samples = 122) 

Table 4. Pittsburgh Airport Ammonia as N Concentrations for Post-Urea Ban Timefram

Airport Source Urea Use Year 

Minimum Ammonia 

Concentration (mg/L)

Maximum Ammonia 

Concentration (mg/L)

Average Ammonia 

Concentration (mg/L

Pittsburgh 15 No 2000 0.05 0.45 0.23 Pittsburgh 15 No 2001 0.05 0.41 0.2 Pittsburgh 15 No 2002 0.06 0.07 0.065 Pittsburgh 15 No 2003 0.05 0.06 0.055 Pittsburgh 15 No 2004 0.05 0.06 0.055 Pittsburgh 15 No 2005 0.08 0.08 0.08 Pittsburgh 15 No 2006 0.05 0.06 0.055 Pittsburgh 15 No 2007 0.06 0.12 0.09 Pittsburgh 15 No 2000 0.05 0.53 0.33 Pittsburgh 15 No 2001 0.23 0.44 0.33 Pittsburgh 15 No 2002 0.3 0.39 0.34 Pittsburgh 15 No 2003 0.23 0.33 0.28 Pittsburgh 15 No 2004 0.15 0.23 0.19 Pittsburgh 15 No 2005 0.12 0.3 0.21 Pittsburgh 15 No 2006 0.09 0.15 0.12 Pittsburgh 15 No 2007 0.12 0.23 0.17 Pittsburgh 15 No 2000 0.05 0.51 0.16 Pittsburgh 15 No 2001 0.05 0.2 0.125 Pittsburgh 15 No 2002 0.06 0.09 0.075 
Memorandum 

June 30, 2009 Page 7 

Table 4. Pittsburgh Airport Ammonia as N Concentrations for Post-Urea Ban Timefram

Airport Source Urea Use Year 

Minimum Ammonia 

Concentration (mg/L)

Maximum Ammonia 

Concentration (mg/L)

Average Ammonia 

Concentration (mg/L

Pittsburgh 15 No 2003 0.05 0.05 0.05 Pittsburgh 15 No 2004 0.05 0.06 0.055 Pittsburgh 15 No 2005 0.05 0.14 0.095 Pittsburgh 15 No 2006 0.05 0.1 0.075 Pittsburgh 15 No 2007 0.05 0.11 0.08 Pittsburgh 15 No 2000 0.12 0.71 0.33 Pittsburgh 15 No 2001 0.41 1.03 0.72 Pittsburgh 15 No 2002 0.3 1.29 0.795 Pittsburgh 15 No 2003 0.61 0.92 0.765 Pittsburgh 15 No 2004 0.19 0.46 0.325 Pittsburgh 15 No 2005 0.06 0.14 0.1 Pittsburgh 15 No 2006 0.15 0.25 0.2 Pittsburgh 15 No 2007 0.07 0.18 0.125 Pittsburgh 15 No 2000 1.61 3.99 3.06 Pittsburgh 15 No 2001 1.2 1.2 1.2 Pittsburgh 15 No 2002 0.82 6.54 2.56 Pittsburgh 15 No 2003 0.3 6.86 2.23 Pittsburgh 15 No 2004 0.05 3.13 1.65 Pittsburgh 15 No 2005 0.34 5.18 1.25 Pittsburgh 15 No 2006 0.28 3.88 1.5 Pittsburgh 15 No 2007 0.16 4 1.19 

Outfall E100: Airfield stormwater to east tributary of Enlow Run. Outfall 21 and 21B: Airfield stormwater to west fork of McClarens Run. Outfall 22: Airfield stormwater to east tributary of McClarens Run. Outfall 063: Discharge point for the north runway. 
Memorandum 

June 30, 2009 

Page 8 

Sources 

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Ouseburn, Newcastle Upon Tyne.” Environmental Pollution 88 (1995) 321-332. 

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4. Ohio EPA. Biological and Water Quality Study of Mill Creek. Dayton International 

Airport. February 20, 1995. 

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June 21, 2000. OPEA Technical Report # MAS/1999-12/-3. 

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Environmental Toxicology and Chemistry, Vol. 20, No. 7, pp. 1474-1482, 2001. 

11. Corsi, Steven R., et. al. “Aquatic Toxicity of Airfield-Pavement Deicer Materials and 

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