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 urea-based 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. 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 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 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.  Table 2. Typical Ammonia
Concentrations in Airport Deicing Stormwaters



Airport	Source	Indication of Urea Use	Ammonia as N

‌Concentration Range (mg/L)	Deicing Stormwater Description

Greater Rockford	1	Yes	ND (0.5) – 82 	Airport submitted data (average
was 24 mg/l), 1999

Albany	1	Yes	88	Contents of the small lagoon, EPA sampling, airport
reported this concentration was an anomaly and they usually see < 45
mg/L

Albany	1	Yes	84	Composite of large lagoon and tank, EPA sampling, 1999

Bradley	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 mg/L, 1997/1998

Chicago O’Hare	1	Not specified	0.2 – 50	PCS data pull, N drainage,
avg. effluent = 11.2 mg/L, 1997/1998

Chicago O’Hare	1	Not specified	0.6 – 10	PCS data pull, NE drainage,
avg. effluent = 3.4 mg/L, 1997/1998

Chicago O’Hare	1	Not specified	2.6 – 85	PCS data pull, SE drainage,
avg. effluent = 35.1 mg/L, 1997/1998

Chicago O’Hare	1	Not specified	0.7 – 37.5	PCS data pull, SW
drainage, avg. effluent = 8.28 mg/L, 1997/1998

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, avg. effluent = <17.2,
1997/1998

Newcastle International Airport (United Kingdom)	2	Yes	105.7 (ammonia)
Measured at airport tributary, mean total ammonia concentrations from
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 mg/L (ammonia)

Dayton International	4	Yes	Max of 161 mg/L	Dayton airport
self-monitoring data reported for 1994 at the retention basin.

Dayton International	5	Yes	11.3 – 13.7	Sampling results from the
Dayton airport northwest retention basin spillway overflow, Ohio EPA
sampling in February and April 1995.

Greater Cincinnati International	7	Not specified	39.1 (ammonia)	High
value at Station 4. Downstream of box culvert location draining runoff
from the taxi lane and runway in the DHL Airlines area.

BWI 	8	Yes	32 (ammonia)	Stormwater discharge pipe prior to discharge to
Kitten Branch, peak sample was 32 mg/L; composite sample was 40 mg/L
ammonia. Sampling occurred 2/26/93 during deicing event at the airport.

General Mitchell International Airport	9	Yes	Max of 25.4 (ammonia)
Sampled at Wilson Park Creek at the airport outfall 7 , sampled April
12, 1997

General Mitchell International Airport	10	Yes	16 (ammonia)	Sampled at
Wilson Park Creek at the airport outfall 7, sampled April 28, 1997

Western Pennsylvania airport (unnamed)	11	Yes	53.3	Concentrations as
high as 53.3 mg/L ammonia as N from breakdown of urea reported in
airport runoff samples

Canadian airports	12	Not specified	0.11 – 17 (total ammonia)	Chemical
analyses for environmental samples (runoff water)

Detroit Metropolitan	14	Yes	0.01 – 13.7 (ammonia)	Pond 3 concentration
range for submitted data prior to urea ban

Detroit Metropolitan	14	Yes	0.02 – 15.9 (ammonia)	Pond 4 concentration
range for submitted data prior to urea ban

Detroit Metropolitan	14	Yes	0.01 – 26.9 (ammonia)	Pond 6 concentration
range for submitted data prior to urea ban

Concentrations reported are for ammonia as N unless otherwise indicated.

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

Airport	Source	Urea Use	Ammonia Concentration Range (mg/L)	Deicing
Stormwater Description

Detroit Metropolitan	14	No	0 – 1.5 (0.25 avg.)	Pond 4 – flow from
Pond 3E discharge to Frank and Poet Drains (includes runway/taxiway
runoff) (# samples = 52)

Detroit Metropolitan	14	No	0 – 2 (0.14 avg.)	Pond 6 – runway/taxiway
drainage from 3R/21L; portion 3L/21R; portion 4R/22L; 4L/22R; and 9R/27L
(# samples = 122)



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



Airport	Source	Urea Use	Year	Minimum Ammonia Concentration (mg/L)
Maximum Ammonia Concentration (mg/L)	Average Ammonia Concentration
(mg/L)	Outfall

Pittsburgh	15	No	2000	0.05	0.45	0.23	E100

Pittsburgh	15	No	2001	0.05	0.41	0.2	E100

Pittsburgh	15	No	2002	0.06	0.07	0.065	E100

Pittsburgh	15	No	2003	0.05	0.06	0.055	E100

Pittsburgh	15	No	2004	0.05	0.06	0.055	E100

Pittsburgh	15	No	2005	0.08	0.08	0.08	E100

Pittsburgh	15	No	2006	0.05	0.06	0.055	E100

Pittsburgh	15	No	2007	0.06	0.12	0.09	E100

Pittsburgh	15	No	2000	0.05	0.53	0.33	21

Pittsburgh	15	No	2001	0.23	0.44	0.33	21

Pittsburgh	15	No	2002	0.3	0.39	0.34	21

Pittsburgh	15	No	2003	0.23	0.33	0.28	21

Pittsburgh	15	No	2004	0.15	0.23	0.19	21

Pittsburgh	15	No	2005	0.12	0.3	0.21	21

Pittsburgh	15	No	2006	0.09	0.15	0.12	21

Pittsburgh	15	No	2007	0.12	0.23	0.17	21

Pittsburgh	15	No	2000	0.05	0.51	0.16	21B

Pittsburgh	15	No	2001	0.05	0.2	0.125	21B

Pittsburgh	15	No	2002	0.06	0.09	0.075	21B

Pittsburgh	15	No	2003	0.05	0.05	0.05	21B

Pittsburgh	15	No	2004	0.05	0.06	0.055	21B

Pittsburgh	15	No	2005	0.05	0.14	0.095	21B

Pittsburgh	15	No	2006	0.05	0.1	0.075	21B

Pittsburgh	15	No	2007	0.05	0.11	0.08	21B

Pittsburgh	15	No	2000	0.12	0.71	0.33	22

Pittsburgh	15	No	2001	0.41	1.03	0.72	22

Pittsburgh	15	No	2002	0.3	1.29	0.795	22

Pittsburgh	15	No	2003	0.61	0.92	0.765	22

Pittsburgh	15	No	2004	0.19	0.46	0.325	22

Pittsburgh	15	No	2005	0.06	0.14	0.1	22

Pittsburgh	15	No	2006	0.15	0.25	0.2	22

Pittsburgh	15	No	2007	0.07	0.18	0.125	22

Pittsburgh	15	No	2000	1.61	3.99	3.06	063

Pittsburgh	15	No	2001	1.2	1.2	1.2	063

Pittsburgh	15	No	2002	0.82	6.54	2.56	063

Pittsburgh	15	No	2003	0.3	6.86	2.23	063

Pittsburgh	15	No	2004	0.05	3.13	1.65	063

Pittsburgh	15	No	2005	0.34	5.18	1.25	063

Pittsburgh	15	No	2006	0.28	3.88	1.5	063

Pittsburgh	15	No	2007	0.16	4	1.19	063

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.

Sources

U.S. Environmental Protection Agency/Office of Water. Preliminary Data
Summary:  Airport Deicing Operations. EPA-821-R-00-016, Washington, D.C.

Turnbull, DA, Bevan, JR. “The Impact of Airport De-icing on a River: 
The Case of the Ouseburn, Newcastle Upon Tyne.” Environmental
Pollution 88 (1995) 321-332.

Sills, Robert D, et. al. The Environmental Impact of Deicers in airport
Stormwater Runoff. 

Ohio EPA. Biological and Water Quality Study of Mill Creek. Dayton
International Airport. February 20, 1995.

Ohio EPA. Biological and Water Quality Study of Mill Creek – 1995.
Dayton International Airport. July 30, 1996.

Ohio EPA. Biological and Water Quality Study of the Little Miami River
Basin, 1998. June 21, 2000. OPEA Technical Report # MAS/1999-12/-3.

Kentucky Department of Environmental Protection, Division of Water.
Impacts of Deicing Fluids on Elijahs and Gunpowder Creeks Boone County,
Kentucky. 

Fisher, Daniel J., et. al. “The Acute Whole Effluent Toxicity of Storm
Water from an International Airport.” Environmental Toxicology and
Chemistry, Vol. 14, No. 6, pp. 1103-1111, 1995.

Corsi, Steven R., et. al. “Aircraft and Runway Deicers at General
Mitchell International Airport, Milwaukee, Wisconsin, USA. 1.
Biochemical Oxygen Demand and Dissolved Oxygen in Receiving Streams.”
Environmental Toxicology and Chemistry, Vol. 20, No. 7, pp. 1474-1482,
2001.

Corsi, Steven R., et. al. “Aircraft and Runway Deicers at General
Mitchell International Airport, Milwaukee, Wisconsin, USA. 2. Toxicity
of Aircraft and Runway Deicers.” Environmental Toxicology and
Chemistry, Vol. 20, No. 7, pp. 1474-1482, 2001.

Corsi, Steven R., et. al. “Aquatic Toxicity of Airfield-Pavement
Deicer Materials and Implications for Airport Runoff.” Environmental
Science and Technology, Vol. 43, No. 1, 2009. 

Novak, Lesley J., et. al. “Acute Toxicity of Storm Water Associated
with De-Icing/Anti-Icing Activities at Canadian Airports.”
Environmental Toxicology and Chemistry, Vol. 19, No. 7, pp. 1846-1855,
2000.

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 Ammonia is a breakdown product of urea-based deicing fluids

Memorandum

June 30, 2009

Page   PAGE  5 

