Document ID: EPA-HQ-OW-2004-0038-1107
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2009-08-28T04:00Z

MEMORANDUM

TO:		Brian D’Amico, USEPA/OW/EAD

FROM:	Cortney Itle, ERG

DATE:	April 17, 2008 

SUBJECT:	Airport Deicing Loading Calculations

EPA is currently evaluating the airport deicing operations point source
category for the development of effluent limitations and guidelines
(ELG).  To support this work, EPA tasked ERG with the development of
baseline pollutant loading estimates for the industry and determination
of pollutant removals associated with various regulatory options.  The
purpose of this memorandum is to describe the draft methodology and
calculations used to estimate pollutant loadings and loading removals
from U.S. airport deicing operations.  

1.0	Background

Aircraft deicing and anti-icing fluids (ADF) and pavement deicing
chemicals are applied at airports to remove and prevent snow and ice
build-up on aircraft and airfield pavement.  These chemicals commingle
with stormwater and may be discharged to the environment.  These
discharges are of environmental concern because the biodegradation of
deicing chemicals results in oxygen depletion in the receiving water
body.   The oxygen demand of compounds can be measured as five-day
Biochemical Oxygen Demand (BOD5) and Chemical Oxygen Demand (COD), or
calculated as Theoretical Oxygen Demand (ThOD).  

Pollutant loadings from airport deicing operations are challenging to
estimate because they are highly variable and airport-specific.  Because
the use of deicing and anti-icing chemicals is weather dependent, the
pollutant loadings at each airport vary based on weather conditions; the
pollutant loadings also vary from airport to airport based on each
airport’s climate.  In addition, the amount of applied chemical that
is discharged to surface water is airport specific, based on the
existing stormwater separation, collection, and/or containment present
at each airport.    

Due to the variations of the pollutant discharges, EPA and ERG
determined that it would not be appropriate to develop baseline
pollutant loadings using end-of-pipe monitoring data.  Monitoring data
on an airport’s deicing stormwater outfall(s) provide only a “snap
shot” of a single point in time, during a monthly monitoring event or
in some cases, a single event storm event.  In addition, these data are
available only for a select number of airports and are airport-specific.
 Although these data provide information on the types of pollutants
present in airport deicing stormwater and the range of concentrations
that may reach outfall points, there is insufficient basis for
extrapolating or transferring the data across large timeframes (e.g., an
entire winter season) or to other airports.

Therefore, ERG developed a pollutant loading estimation methodology
based on the usage of ADF and airfield chemicals at the airports
surveyed by EPA.  The methodology takes into account EPA’s existing
data sources and should provide a better estimate of the loadings than
those based on sporadic monitoring data alone.

2.0	Data Sources

ERG considered the available data when developing a pollutant loadings
estimation methodology for airport deicing operations.  The existing
data that had the potential to contribute to the loads analysis included
(see Section 4 for more information about the data sources):

Pavement deicing chemical usage/purchase information for the 2002/2003,
2003/2004, and 2004/2005 deicing seasons, as reported by airport
personnel in the Airport Deicing Operations Questionnaire;

ADF purchase information for the 2002/2003, 2003/2004, and 2004/2005
deicing seasons, as reported by airline personnel in the Airline Deicing
Questionnaire;

Standard airport information available from the Federal Aviation
Administration (FAA), including the number of operations and departures
by airport;

Weather information for each airport from National Oceanic and
Atmospheric Administration (NOAA), including temperature, freezing
precipitation, and snowfall data;

Existing airport stormwater collection and containment systems, as
reported by airport personnel in the Airport Deicing Operations
Questionnaire;

Standard chemical information about ADF and pavement deicing chemicals,
including molecular formulas and densities; 

Analytical data from EPA sampling episodes of airport deicing
operations.

3.0	Pollutant Loadings Methodology

 

	ERG developed a methodology to estimate pollutant loadings based on the
available data listed above.  The pollutant loading estimation
methodology is as follows:

Step 1:	Estimate the amount of ADF and pavement deicing chemicals
applied at each airport during a typical winter season;

Step 2:	Calculate the amount of pollutant load associated with the
applied chemicals, based on the chemical properties of the chemicals;

Step 3:	Estimate the amount of the applied chemical’s pollutant load
that is discharged directly, based on the airport’s existing
stormwater separation, collection, and/or containment system.

Step 4: Estimate pollutant loading removals for each EPA regulatory
option.

Step 5: Scale the loading removal estimates up to represent the entire
industry.

The sections below describe each step in detail. 

3.1	Step 1:	Estimate the amount of applied ADF and pavement deicing
chemicals 

To estimate pollutant loadings from airport deicing operations, ERG
first estimated the amount of applied pavement deicing chemicals and ADF
based on data collected in EPA’s Airport and Airline Deicing
Questionnaires.  In the airport questionnaire, EPA requested usage data
for pavement deicing chemicals.  In the airline questionnaires, EPA
requested ADF purchase data instead of usage data because airport and
airline personnel reported to EPA during the questionnaire development
process that purchase data are documented and tracked more frequently
than usage data.  The reported amount of chemical purchased was used as
a surrogate for the amount of chemical applied.  EPA requested data for
the past three winter seasons (2002/2003, 2003/2004, and 2004/2005);
these data were averaged for each airport to capture any variability in
the severity of the winter weather over the past three years.  

The EPA Airport Deicing Detailed Questionnaire was sent to 153 airports.
 EPA selected the airports using a stratified random sample of airports
based on airport type (i.e., hub, non-hub), the number of snow or other
freezing precipitation (SOFP) days, and the number of departures.

The Airline Deicing Detailed Questionnaire collected information from 58
airlines that completed plane deicing based on the Airline Screener
Questionnaire responses.  These 58 airlines represented 448
airline/airport combinations.  

Pavement Deicing and Pavement Anti-icing Chemical Usage Estimate

In the EPA Airport Deicing Detailed Questionnaire, EPA requested that
airport personnel report the purchase/usage amount, concentration, and
brand name of the following pavement deicing materials for the
2002/2003, 2003/2004, and 2004/2005 deicing seasons:

Airside Urea;

Potassium Acetate;

Calcium Magnesium Acetate (CMA);

Sodium Acetate; 

Sand; 

Sodium Formate; 

Ethylene Glycol-Based Fluids; 

Propylene Glycol-Based Fluids; and 

Other: (Specify).

ERG evaluated each reported chemical to determine the most appropriate
way to estimate the average amount used over the past three winter
seasons.  In addition, ERG read the comments provided by the airport
personnel to determine any extenuating circumstances that impact
chemical use.  For example, airport personnel may have reported that
urea was replaced with potassium acetate at the airport over the past
three years.  In this case, ERG used the potassium acetate average in
the loadings estimate and did not use any of the urea data in order to
better represent the airport.  

ADF Usage Estimate 

EPA requested the purchase amount, concentration, and brand name in
EPA’s Airline Deicing Questionnaire for the 2002/2003, 2003/2004, and
2004/2005 deicing seasons for the following ADF chemicals:

Type I Ethylene Glycol-Based Fluid (EG Type I);

Type II Ethylene Glycol-Based Fluid (EG Type II);

Type IV Ethylene Glycol-Based Fluid (EG Type IV);

Type I Propylene Glycol-Based Fluid (PG Type I);

Type II Propylene Glycol-Based Fluid (PG Type II);

Type III Propylene Glycol-Based Fluid (PG Type III);

Type IV Propylene Glycol-Based Fluid (PG Type IV); and

Isopropyl Alcohol-Based Fluid.

Airline Detailed Questionnaire responses provided sufficient data to
estimate ADF usage at 56 airports.  In some cases, data were not
available for every airline operating at an airport.  In these
instances, ERG extrapolated the amount of ADF used at the reporting
airlines to estimate the total amount of ADF used by the entire airport.
This was done based on the number of airport operations (departures) at
the reporting airlines and the total amount of airport operations. 
Table 1 presents the estimates of ADF usage based on airline
questionnaire responses

Table 1.  ADF Estimates Based on Airline Questionnaire Responses

Airport ID	Airport Name	Estimated PG/EG Gallons per Year	Percent PG Type
I	Percent PG Type IV	Percent EG Type 1	Percent EG Type IV

1003	Ketchikan Intl	18,182	0%	0%	100%	0%

1006	Chicago O'Hare Intl	1,516,626	80%	20%	0%	0%

1010	Fairbanks Intl	83,335	0%	0%	100%	0%

1011	Lambert - St Louis Intl	325,122	23%	1%	70%	6%

1012	Ted Stevens Anchorage Intl	420,735	0%	0%	100%	0%

1013	Wiley Post-Will Rogers Mem	3,056	9%	0%	91%	0%

1021	Buffalo Niagara Intl	281,836	92%	9%	0%	0%

1022	Fort Wayne Intl	50,412	92%	8%	0%	0%

1024	Indianapolis Intl	452,155	91%	9%	0%	0%

1026	Dallas/Fort Worth Intl	166,790	43%	12%	38%	7%

1028	Denver Intl	1,043,138	87%	10%	4%	0%

1029	La Guardia	485,157	75%	22%	2%	1%

1036	Baltimore - Washington Intl	323,623	90%	10%	0%	0%

1037	George Bush Intercontinental	10,242	82%	18%	0%	0%

1043	Ralph Wien Memorial	2,500	27%	0%	73%	0%

1047	Sacramento Mather	1,282	100%	0%	0%	0%

1053	General Edward Lawrence Logan Intl	995,249	82%	17%	0%	0%

1058	Gerald R Ford Intl	98,156	86%	13%	0%	0%

1059	Greater Rochester Intl	229,158	91%	9%	0%	0%

1065	Albany Intl	125,775	93%	7%	0%	0%

1066	Salt Lake City Intl	570,540	22%	6%	52%	20%

1069	Cleveland - Hopkins Intl	582,321	90%	10%	0%	0%

1074	South Bend Regional	29,586	75%	25%	0%	0%

1079	Manchester	177,307	87%	13%	0%	0%

1080	Syracuse Hancock Intl	186,351	97%	3%	0%	0%

1089	John F Kennedy Intl	560,031	82%	18%	0%	0%

1095	Chicago Midway Intl	293,834	88%	12%	0%	0%

1100	Toledo Express	46,449	64%	5%	29%	2%

1103	Juneau Intl	48,014	0%	0%	100%	0%

1104	Nome	3,047	15%	0%	85%	0%

1105	Spokane Intl	67,984	92%	8%	0%	0%

1107	Pittsburgh Intl	943,982	88%	12%	0%	0%

1109	Airborne Airpark	432,416	74%	26%	0%	0%

1110	Aniak	476	100%	0%	0%	0%

1111	Port Columbus Intl	288,374	92%	8%	0%	0%

1113	Cincinnati/Northern Kentucky Intl	715,836	24%	5%	61%	11%

1117	Cherry Capital	11,524	75%	0%	0%	25%

1118	Bethel	4,897	40%	0%	60%	0%

1123	James M Cox Dayton Intl	90,580	89%	11%	0%	0%

1124	Des Moines Intl	79,658	84%	14%	3%	0%

1126	Minneapolis - St Paul Intl/Wold - Chamberlain	1,456,537	93%	7%	0%
0%

1128	Charlotte/Douglas Intl	143,572	81%	19%	0%	0%

1129	Bradley Intl	427,068	88%	12%	0%	0%

1136	General Mitchell Intl	152,944	90%	9%	0%	1%

1138	Detroit Metropolitan Wayne County	2,152,292	93%	7%	0%	0%

1139	Philadelphia Intl	979,983	88%	12%	0%	0%

1140	Memphis Intl	199,174	88%	12%	0%	0%

1141	Ronald Reagan Washington National	219,533	81%	16%	3%	0%

1142	Washington Dulles Intl	1,076,083	77%	22%	1%	0%

1145	Newark Liberty Intl	1,123,057	86%	14%	0%	0%

1148	Kansas City Intl	203,726	75%	8%	17%	0%

1149	Fort Worth Alliance	1,522	97%	3%	0%	0%

1150	Greater Rockford	146,856	79%	21%	0%	0%

1151	Kalamazoo/Battle Creek Intl	22,002	84%	16%	0%	0%

1152	Duluth Intl	68,168	96%	4%	0%	0%

1153	Akron - Canton Regional	60,246	90%	10%	0%	0%

In addition to the ADF data reported in the Airline Detailed Deicing
Questionnaire, 10 airports reported total gallons of ADF usage to EPA in
their comment section of the Airport Deicing Questionnaire (see Table
2).  These ADF data were combined with the ADF data reported in the
Airline Deicing Questionnaires, resulting in 66 airports with total
PG/EG (gallons) usage estimates.

Table 2. ADF Data Reported in the Airport Questionnaire

Airport ID	Airport Name	PG/EG Gallons

1115	Jacksonville Intl	1,000

1062	Birmingham Intl	5,000

1072	Gillette-Campbell County	880

1060	Williamson County Regional	150

1096	Santa Fe Municipal	1,108

1097	Lovell Field	4,148

1025	Tupelo Regional	820

1143	San Francisco International	105

1001	Montgomery Rgnl (Dannelly Field)	232

1019	Ontario Intl	35

Using the airline and airport questionnaire ADF purchase data, airport
departure data, and climate data, ERG developed a relationship between
the estimate of amount of ADF used versus the climate and size of each
airport.    ERG created an “ADF factor” to estimate the relative
amount of deicing occurring at each airport based on the airport’s
climate and number of departures.  ERG calculated the ADF factor by
multiplying the 30 year annual average number of snow and freezing
precipitation (SOFP) days by the average number of annual departures at
each airport during 2004-2006 (see DCN AD00856).  ERG graphed the total
gallons of PG/EG with the ADF factor and determined the equation of the
line.  During this analysis, EPA noted a difference in the relationship
of ADF Factor and ADF usage for Alaskan airports compared to other
airports. Due to this difference, EPA developed a separate graph and
equation for Alaskan airports. The graph for non-Alaskan airports is
presented in Figure 1; the graph for Alaskan airports is presented in
Figure 2.  ERG used the equations to estimate the total gallons of ADF
used at airports that did not have available ADF data in the airport or
airline questionnaires.  

Figure 1.  ADF Factor vs. PG/EG Gallons for U.S. Airports (excluding
Alaska)

Figure 2. ADF Factor vs. PG/EG Gallons for Alaskan Airports

	Based on the total gallons of ADF used at an airport, ERG estimated the
distribution of different types of ADF (PG/EG, Type I/Type IV) based on
the average percent distribution of the reported ADF amounts.  The final
estimates of ADF for all airports that received the airport
questionnaire are shown in Table 3.

Table 3. ADF Estimates for All Airports that Received the Airport
Deicing Questionnaire

Airport ID	Airport Name	PG/EG Gallons per Year	Percent PG Type I	Percent
PG TypeIV	Percent EG Type 1	Percent EG Type IV

1001	Montgomery Rgnl (Dannelly Field)	232	72%	10%	18%	1%

1002	Bert Mooney	13,587	72%	10%	18%	1%

1003	Ketchikan Intl	18,182	0%	0%	100%	0%

1004	Norfolk Intl	30,864	72%	10%	18%	1%

1005	Roberts Field	14,981	72%	10%	18%	1%

1006	Chicago O'Hare Intl	1,516,626	80%	20%	0%	0%

1007	Yeager	49,543	72%	10%	18%	1%

1008	Tucson Intl	2,341	72%	10%	18%	1%

1009	Cold Bay	61,155	72%	10%	18%	1%

1010	Fairbanks Intl	83,335	0%	0%	100%	0%

1011	Lambert-St Louis Intl	325,122	23%	1%	70%	6%

1012	Ted Stevens Anchorage Intl	420,735	0%	0%	100%	0%

1013	Wiley Post-Will Rogers Mem	3,056	9%	0%	91%	0%

1014	Albuquerque Intl Sunport	64,437	72%	10%	18%	1%

1015	Gulfport-Biloxi Intl	1,550	72%	10%	18%	1%

1016	Tri-State/Milton J. Ferguson Field	12,940	72%	10%	18%	1%

1017	Austin Straubel International	62,110	72%	10%	18%	1%

1018	Piedmont Triad International	68,716	72%	10%	18%	1%

1019	Ontario Intl	35	72%	10%	18%	1%

1020	Hartsfield - Jackson Atlanta Intl	362,106	72%	10%	18%	1%

1021	Buffalo Niagara Intl	281,836	92%	9%	0%	0%

1022	Fort Wayne International	50,412	92%	8%	0%	0%

1023	Seattle-Tacoma Intl	157,408	72%	10%	18%	1%

1024	Indianapolis Intl	452,155	91%	9%	0%	0%

1025	Tupelo Regional	820	72%	10%	18%	1%

1026	Dallas/Fort Worth International	166,790	43%	12%	38%	7%

1027	Craven County Regional	878	72%	10%	18%	1%

1028	Denver Intl	1,043,138	87%	10%	4%	0%

1029	La Guardia	485,157	75%	22%	2%	1%

1030	Williamsport Regional	10,068	72%	10%	18%	1%

1031	Richmond Intl	59,316	72%	10%	18%	1%

1032	Austin-Bergstrom Intl	24,036	72%	10%	18%	1%

1033	Mc Carran Intl	10,640	72%	10%	18%	1%

1034	Metropolitan Oakland Intl	0	72%	10%	18%	1%

1035	San Diego Intl	0	72%	10%	18%	1%

1036	Baltimore-Washington Intl	323,623	90%	10%	0%	0%

1037	George Bush Intercontinental Arpt/Houston	10,242	82%	18%	0%	0%

1038	Luis Munoz Marin Intl	0	72%	10%	18%	1%

1039	Kahului	0	72%	10%	18%	1%

1040	Louis Armstrong New Orleans Intl	0	72%	10%	18%	1%

1041	Glacier Park Intl	38,541	72%	10%	18%	1%

1042	Orlando Intl	0	72%	10%	18%	1%

1043	Ralph Wien Memorial	2,500	27%	0%	73%	0%

1044	Roanoke Regional/Woodrum Field	32,915	72%	10%	18%	1%

1045	Norman Y. Mineta San Jose International	0	72%	10%	18%	1%

1046	Long Island Mac Arthur	43,512	72%	10%	18%	1%

1047	Sacramento Mather	1,282	100%	0%	0%	0%

1048	Redding Municipal	692	72%	10%	18%	1%

1049	Lanai	0	72%	10%	18%	1%

1050	Aspen-Pitkin Co/Sardy Field	15,013	72%	10%	18%	1%

1051	Barnstable Muni-Boardman/Polando Field	46,130	72%	10%	18%	1%

1052	Wilmington Intl	2,175	72%	10%	18%	1%

1053	General Edward Lawrence Logan Intl	995,249	82%	17%	0%	0%

1054	Jackson Hole	34,119	72%	10%	18%	1%

1055	Miami Intl	0	72%	10%	18%	1%

1056	Santa Maria Pub/Capt G Allan Hancock Fld	0	72%	10%	18%	1%

1057	Will Rogers World	49,486	72%	10%	18%	1%

1058	Gerald R. Ford International	98,156	86%	13%	0%	0%

1059	Greater Rochester International	229,158	91%	9%	0%	0%

1060	Williamson County Regional	150	72%	10%	18%	1%

1061	William P Hobby	14,163	72%	10%	18%	1%

1062	Birmingham Intl	5,000	72%	10%	18%	1%

1063	Evansville Regional	20,141	72%	10%	18%	1%

1064	Falls Intl	11,372	72%	10%	18%	1%

1065	Albany Intl	125,775	93%	7%	0%	0%

1066	Salt Lake City Intl	570,540	22%	6%	52%	20%

1067	Helena Regional	18,373	72%	10%	18%	1%

1068	Eppley Airfield	110,946	72%	10%	18%	1%

1069	Cleveland-Hopkins Intl	582,321	90%	10%	0%	0%

1070	City of Colorado Springs Municipal	75,789	72%	10%	18%	1%

1071	Tweed-New Haven	4,924	72%	10%	18%	1%

1072	Gillette-Campbell County	880	72%	10%	18%	1%

1073	Honolulu Intl	0	72%	10%	18%	1%

1074	South Bend Regional	29,586	75%	25%	0%	0%

1075	Pensacola Regional	827	72%	10%	18%	1%

1077	Kona Intl at Keahole	0	72%	10%	18%	1%

1078	Nashville Intl	91,511	72%	10%	18%	1%

1079	Manchester	177,307	87%	13%	0%	0%

1080	Syracuse Hancock Intl	186,351	97%	3%	0%	0%

1081	Bob Hope	0	72%	10%	18%	1%

1082	Trenton Mercer	5,392	72%	10%	18%	1%

1083	Tampa Intl	0	72%	10%	18%	1%

1084	Bismarck Municipal	20,989	72%	10%	18%	1%

1085	Waterloo Municipal	7,818	72%	10%	18%	1%

1086	Palm Beach Intl	1,023	72%	10%	18%	1%

1087	El Paso Intl	16,222	72%	10%	18%	1%

1088	Outagamie County Regional	57,824	72%	10%	18%	1%

1089	John F Kennedy Intl	560,031	82%	18%	0%	0%

1090	Boise Air Terminal/Gowen Fld	71,396	72%	10%	18%	1%

1091	Rochester International	34,544	72%	10%	18%	1%

1092	Lewiston-Nez Perce County	24,850	72%	10%	18%	1%

1093	Los Angeles Intl	0	72%	10%	18%	1%

1094	Boeing Field/King County Intl	5,154	72%	10%	18%	1%

1095	Chicago Midway Intl	293,834	88%	12%	0%	0%

1096	Santa Fe Municipal	1,108	72%	10%	18%	1%

1097	Lovell Field	4,148	72%	10%	18%	1%

1098	Aberdeen Regional	13,972	72%	10%	18%	1%

1099	Sacramento International	0	72%	10%	18%	1%

1100	Toledo Express	46,449	64%	5%	29%	2%

1101	Portland Intl	112,046	72%	10%	18%	1%

1102	John Wayne Airport-Orange County	0	72%	10%	18%	1%

1103	Juneau Intl	48,014	0%	0%	100%	0%

1104	Nome	3,047	15%	0%	85%	0%

1105	Spokane Intl	67,984	92%	8%	0%	0%

1106	Fort Lauderdale/Hollywood Intl	0	72%	10%	18%	1%

1107	Pittsburgh International	943,982	88%	12%	0%	0%

1108	Louisville Intl-Standiford Field	128,363	72%	10%	18%	1%

1109	Airborne Airpark	432,416	74%	26%	0%	0%

1110	Aniak	476	100%	0%	0%	0%

1111	Port Columbus Intl	288,374	92%	8%	0%	0%

1112	Deadhorse	78,931	72%	10%	18%	1%

1113	Cincinnati/Northern Kentucky International	715,836	24%	5%	61%	11%

1114	Stewart Intl	32,264	72%	10%	18%	1%

1115	Jacksonville Intl	1,000	72%	10%	18%	1%

1116	Reno/Tahoe International	74,604	72%	10%	18%	1%

1117	Cherry Capital	11,524	75%	0%	0%	25%

1118	Bethel	4,897	40%	0%	60%	0%

1119	Rickenbacker International	10,707	72%	10%	18%	1%

1120	Rapid City Regional	25,414	72%	10%	18%	1%

1121	Theodore Francis Green State	150,074	72%	10%	18%	1%

1122	Southwest Florida Intl	951	72%	10%	18%	1%

1123	James M Cox Dayton Intl	90,580	89%	11%	0%	0%

1124	Des Moines Intl	79,658	84%	14%	3%	0%

1125	Sarasota/Bradenton Intl	0	72%	10%	18%	1%

1126	Minneapolis-St Paul Intl/Wold-Chamberlain	1,456,537	93%	7%	0%	0%

1127	Willow Run	10,220	72%	10%	18%	1%

1128	Charlotte/Douglas Intl	143,572	81%	19%	0%	0%

1129	Bradley Intl	427,068	88%	12%	0%	0%

1130	San Antonio Intl	12,745	72%	10%	18%	1%

1131	Wilkes-Barre/Scranton Intl	42,522	72%	10%	18%	1%

1132	Chippewa Valley Regional	13,257	72%	10%	18%	1%

1133	Phoenix Sky Harbor Intl	0	72%	10%	18%	1%

1134	St George Municipal	13,944	72%	10%	18%	1%

1135	Lafayette Regional	1,488	72%	10%	18%	1%

1136	General Mitchell International	152,944	90%	9%	0%	1%

1137	Dallas Love Field	37,205	72%	10%	18%	1%

1138	Detroit Metropolitan Wayne County	2,152,292	93%	7%	0%	0%

1139	Philadelphia Intl	979,983	88%	12%	0%	0%

1140	Memphis Intl	199,174	88%	12%	0%	0%

1141	Ronald Reagan Washington National	219,533	81%	16%	3%	0%

1142	Washington Dulles International	1,076,083	77%	22%	1%	0%

1143	San Francisco International	105	72%	10%	18%	1%

1144	Central Wisconsin	43,608	72%	10%	18%	1%

1145	Newark Liberty Intl	1,123,057	86%	14%	0%	0%

1146	Northwest Arkansas Regional	30,764	72%	10%	18%	1%

1147	Raleigh-Durham Intl	102,415	72%	10%	18%	1%

1148	Kansas City Intl	203,726	75%	8%	17%	0%

1149	Fort Worth Alliance	1,522	97%	3%	0%	0%

1150	Greater Rockford	146,856	79%	21%	0%	0%

1151	Kalamazoo/Battle Creek Intl	22,002	84%	16%	0%	0%

1152	Duluth Intl	68,168	96%	4%	0%	0%

1153	Akron - Canton Regional	60,246	90%	10%	0%	0%

3.2	Step 2:	Calculate the amount of pollutant load associated with the
applied chemicals

	ERG calculated the amount of COD loading associated with the
degradation of the applied deicing/anti-icing chemicals.  ERG considered
two approaches to estimate loadings: using empirical data, or using
standard chemical information and stoichiometric equations.

ERG determined it would not be suitable to use empirical data to
estimate loadings because of three main reasons.  First, empirical data
were not readily available for all deicing/anti-icing chemicals. 
Secondly, the available empirical data were outdated and brand-specific.
 Finally, chemical formulations vary significantly over time and by
brand, so it is inappropriate to apply any given set of empirical data
to all airports and chemicals.  

As an alternative to using empirical data, ERG calculated loadings based
on standard chemical information and stoichiometric equations.  This
methodology is advantageous to using empirical data because it can be
used for on all deicing chemicals.  In addition, this methodology allows
for a clear presentation of the calculations and assumptions used.  ERG
checked the validity of the calculated COD and BOD5 concentrations for
propylene glycol and ethylene glycol calculated using this methodology
against the available empirical data and found a good match.    

3.2.1	Step 2, Part 1: Calculate the Total Mass of Each Pollutant 

First, ERG estimated the total mass of each pollutant based on the
Airline and Airport Detailed Questionnaire responses (which specified
varying formulations of ADF and deicing products).  To calculate the
total mass of applied chemical, ERG multiplied the reported mass of each
chemical by the reported concentration of the chemical.  Alternatively,
if airport personnel reported a volume of chemical in the Airport or
Airline Detailed Questionnaire, ERG multiplied the reported volume by
the reported concentration and the chemical density. 

  

3.2.2	Step 2, Part 2: Determine the Theoretical Oxygen Demand of Each
Chemical

Next, ERG determined the theoretical oxygen demand (ThOD) associated
with the degradation of each of the deicing chemicals.  The ThOD
estimate was based on the molecular formula of the chemical and the
stoichiometric equation of the breakdown of the chemical with the end
products of carbon dioxide and water.  The calculated ThOD for each
chemical is presented in Table 4.

Table 4.  Deicing Chemical Information

Deicing Compound	Molecular Formula	Stoichiometric Formula	Moles of O2
per mole of Deicing Compound

Propylene glycol 	C3H8O2	C3H8O2 + 4 O2 (  3 CO2  + 4 H2O

	4.0

Ethylene glycol	C2H6O2	2[C2H6O2] + 5 O2 ( 4 CO2 + 6 H2O

	2.5

Urea	N2H4CO

	N2H4CO + 4 O2 ( 2 HNO3 + CO2 + H2O

	4.0

Potassium acetate	KC2H3O2	[C2H3O2] -  + 1.75 O2 ( 2 CO2 + 1.5 H2O	1.75

Sodium acetate	NaC2H3O2	[C2H3O2] -  + 1.75 O2 ( 2 CO2 + 1.5 H2O	1.75

Calcium magnesium acetate	C8H12CaMgO8

	[C8H12O8]4-  + 7 O2 ( 8 CO2 + 6 H2O	7.0

Sodium formate	NaHCO2

	2[HCO2]-  + 0.5 O2 ( 2 CO2 + H2O	0.25

3.2.3	Step 2, Part 3: Determine the Chemical Oxygen Demand of Each
Chemical

ERG determined the COD produced by the degradation of the chemical.  ERG
assumed that the chemical would completely degrade in the environment
over time and therefore the calculated ThOD would be equivalent to the
COD.  ERG estimated the COD associated with each reported chemical based
on the calculated mass of the chemical, the molecular weight of the
chemical, the ThOD, and the molecular weight of oxygen.   

3.2.4 	Step 2, Part 4: Determine the Biochemical Oxygen Demand of Each
Chemical

ERG calculated the BOD5 loading based on the estimated COD loading.  ERG
developed an industry-specific relationship between COD and BOD5 using
analytical data for untreated deicing stormwater from the EPA sampling
episodes at Albany International Airport, Pittsburgh International
Airport, and Denver International Airport.  The average COD/BOD5 ratio
was 1.67.  This relationship was used to calculate the BOD5 associated
with the degradation of the deicing chemical.  .

3.3	Step 3: Estimate the amount of baseline pollutant load that is
discharged directly

	The amount of applied chemical that is discharged directly is airport
specific and dependant upon the existing stormwater separation,
collection, and/or containment present at each airport.  Typically, ADF
is applied at a number of specific locations including gate, deicing
pads, or aprons.  Pavement deicing chemicals are applied on a larger
area and variety of locations including runways, taxiways, aprons, and
gates.  Based on EPA site visits, and questionnaire responses, ERG
assumes that pavement deicing chemicals could be present in almost every
airport outfall, whereas ADF is usually present at a small number of
outfalls that drain only aircraft deicing areas. 

3.3.1	Direct Discharge Pavement Deicers

	ERG estimated the direct discharge amount of pavement deicers.  Because
pavement deicing chemicals are applied at a large variety of areas at an
airport, the amount of pavement deicers being directly discharged could
range from close to 100 percent, on pavement areas near outfall drains,
to approximately 0 percent, for chemicals that may fall onto grassy
areas and infiltrate into the ground during a thaw.  Estimating a
percentage of direct discharge release of pavement deicers at a
particular airport is difficult without performing a detailed study of
each airport.  Therefore, a range of direct discharge pavement deicing
chemical loads were estimated for each airport; the maximum load assumes
100 percent direct discharge of pavement deicers and the minimum load
assumes 0 percent direct discharge.  

3.2.2	Direct Discharge ADF

ERG estimated the direct discharge amount of ADF by first estimating the
amount of applied ADF that would be available for discharge.  ERG
assumes that 80 percent of applied Type I and Type II ADF falls onto the
pavement at the deicing area and is available for discharge; the
remaining 20 percent is lost to evaporation, wind or tire tracking, or
adheres to the plane and is later sheared off during taxiing and
takeoff.  ERG assumes that 10 percent of Type III and Type IV ADF falls
to the pavement in the deicing area and is available for discharge; the
remaining 90 percent adheres to the plane.  The total amount of applied
ADF was multiplied by the appropriate percent available for discharge to
determine the amount of ADF that is available for discharge.   

Next, ERG determined the percentage of available ADF that would be
direct discharged at each airport, depending on the airport’s current
capture and control systems (See DCN AD00854).  ERG estimated capture
and control percentages of spent ADF for each airport based on
information provided during EPA site visits and in the Airport Detailed
Questionnaire.  If the airport did not provide an ADF percent capture
and control estimate, ERG personnel reviewed the airport’s
questionnaire responses and the reported percent capture and control of
similar systems to determine an estimate for the airport.  These
estimates are presented in Table 5.

The available amount of COD for each ADF chemical applied at an airport
was reduced by the airport’s percent capture and control to estimate
the amount of ADF direct discharged.  Table 5 presents ERG’s estimate
of the amount of ADF load direct discharged by airport, as measured by
pounds of COD,.

Step 4: Estimate pollutant loading removals for each EPA regulatory
option

EPA is developing regulatory options that may require a specific percent
capture and control of available (spent) ADF.  EPA is focusing on ADF
because pavement deicing chemicals are commingled with large quantities
of stormwater and are present at low concentrations.  Also, the capture
and control of pavement deicers would require capturing and controlling
all of an airport’s deicing stormwater which would not be cost
effective.  

EPA’s possible regulatory options include these three scenarios:

Scenario 1: capture and control of 20 percent of spent ADF 

Scenario 2: capture and control of 40 percent of spent ADF 

Scenario 3: capture and control of 60 percent of spent ADF 

ERG estimated the COD loading removals for each airport based on the
existing capture and control present at the airport (as shown in Table 8
in Section 3.2.2) versus that required by the capture and control
scenario.  For Scenario 1, if an airport currently has capture and
control of 20 percent or more, no load removals were estimated for the
airport.   For Scenario 2, if an airport currently has capture and
control of 40 percent or more, no load removals were estimated for the
airport.  For Scenario 3, if an airport currently has capture and
control of 60 percent or more, no load removals were estimated for the
airport.  The pollutant loading removals for each scenario are presented
by airport in Table 5.

Table 5. ADF COD Baseline Loads and Loading Reductions for Each Control
and Treatment Scenario, by Airport

Airport	Current ADF Collection	Baseline COD Load (pounds)	COD Load
Reduction for 20% Collection and Control Scenario (pounds)	COD Load
Reduction for 40% Collection and Control Scenario (pounds)	COD Load
Reduction for 60% Collection and Control Scenario (pounds)

Montgomery Regional (Dannelly Field)	0	2,359	460	920	1,380

Bert Mooney	100	0	0	0	0

Ketchikan International 1	NA	0	0	0	0

Norfolk International	20	251,092	0	61,204	122,408

Roberts Field	100	0	0	0	0

Chicago O'Hare International	40	8,733,878	0	0	2,838,510

Yeager	40	302,292	0	0	98,245

Tucson International	20	19,045	0	4,642	9,285

Cold Bay	0	621,909	121,272	242,545	363,817

Fairbanks International	60	319,152	0	0	0

Lambert-St Louis International	60	1,230,807	0	0	0

Ted Stevens Anchorage International	40	2,416,962	0	0	785,513

Wiley Post-Will Rogers Mem	0	29,821	5,815	11,630	17,445

Albuquerque International Sunport	20	524,227	0	127,780	255,561

Gulfport-Biloxi International	100	0	0	0	0

Tri-State/Milton J. Ferguson Field	0	131,595	25,661	51,322	76,983

Austin Straubel International	40	378,973	0	0	123,166

Piedmont Triad International	0	698,801	136,266	272,532	408,799

Ontario International	0	356	214	214	214

Hartsfield - Jackson Atlanta International	60	1,472,952	0	0	0

Buffalo Niagara International	40	1,832,048	0	0	595,416

Fort Wayne International	0	545,428	109,086	218,171	327,257

Seattle-Tacoma International	0	1,600,739	312,144	624,288	936,432

Indianapolis International	40	2,907,633	0	0	944,981

Tupelo Regional	0	8,339	1,626	3,252	4,878

Dallas/Fort Worth International	60	593,712	0	0	0

Craven County Regional	0	8,928	5,357	5,357	5,357

Denver International	93	777,648	0	0	0

La Guardia	0	4,487,109	874,986	1,749,972	2,624,959

Williamsport Regional	60	40,953	0	0	0

Richmond International	40	361,921	0	0	117,624

Austin-Bergstrom International	40	146,656	0	0	47,663

Mc Carran International	40	64,919	0	0	21,099

Metropolitan Oakland International	100	0	0	0	0

San Diego International	100	0	0	0	0

Baltimore-Washington International	60	1,374,218	0	0	0

George Bush Intercontinental Airport/Houston	40	60,235	0	0	20,078

Luis Munoz Marin International	NA	0	0	0	0

Kahului	NA	0	0	0	0

Louis Armstrong New Orleans International	100	0	0	0	0

Glacier Park International	0	391,940	76,428	152,857	229,285

Orlando International	NA	0	0	0	0

Ralph Wien Memorial	0	25,326	4,939	9,877	14,816

Roanoke Regional/Woodrum Field	0	334,727	65,272	130,544	195,815

Norman Y. Mineta San Jose International	10	0	0	0	0

Long Island Mac Arthur	60	176,997	0	0	0

Sacramento Mather	20	11,932	0	5,966	5,966

Redding Municipal	0	7,035	1,372	2,744	4,116

Lanai	NA	0	0	0	0

Aspen-Pitkin Co/Sardy Field	40	91,601	0	0	30,534

Barnstable Muni-Boardman/Polando Field	0	469,111	91,477	182,953	274,430

Wilmington International	0	22,118	4,313	8,626	12,939

General Edward Lawrence Logan International	0	9,740,474	1,899,392
3,798,785	5,698,177

Jackson Hole	100	0	0	0	0

Miami International

0	0	0	0

Santa Maria Pub/Capt G Allan Hancock Fld	100	0	0	0	0

Will Rogers World	0	503,236	98,131	196,262	294,393

Gerald R. Ford International	40	600,371	0	0	200,124

Greater Rochester International	50	1,228,022	0	0	239,464

Williamson County Regional	100	0	0	0	0

William P Hobby	100	0	0	0	0

Birmingham International	0	50,847	9,915	19,830	29,745

Evansville Regional	0	204,825	39,941	79,882	119,823

Falls International 2	NE	0	0	0	0

Albany International	92	109,890	0	0	0

Salt Lake City International	60	1,794,858	0	0	0

Helena Regional	100	0	0	0	0

Eppley Airfield	0	1,128,249	220,009	440,017	660,026

Cleveland-Hopkins International	40	3,709,111	0	0	1,236,370

City of Colorado Springs Municipal	40	462,436	0	0	150,292

Tweed-New Haven	0	50,074	9,764	19,529	29,293

Gillette-Campbell County	100	0	0	0	0

Honolulu International	NA	0	0	0	0

South Bend Regional	100	0	0	0	0

Pensacola Regional	100	0	0	0	0

Kona International at Keahole	NA	0	0	0	0

Nashville International	60	372,242	0	0	0

Manchester	0	1,828,125	356,484	712,969	1,069,453

Syracuse Hancock International	60	844,427	0	0	0

Bob Hope	100	0	0	0	0

Trenton Mercer	0	54,836	10,693	21,386	32,079

Tampa International	100	0	0	0	0

Bismarck Municipal	0	213,443	41,621	83,243	124,864

Waterloo Municipal	0	79,504	15,503	31,006	46,510

Palm Beach International	100	0	0	0	0

El Paso International	100	0	0	0	0

Outagamie County Regional	0	588,037	114,667	229,335	344,002

John F Kennedy International	0	5,489,149	1,070,384	2,140,768	3,211,152

Boise Air Terminal/Gowen Fld	60	290,420	0	0	0

Rochester International	40	210,773	0	0	68,501

Lewiston-Nez Perce County	100	0	0	0	0

Los Angeles International	NA	0	0	0	0

Boeing Field/King County International	40	31,446	0	0	10,220

Chicago Midway International	100	0	0	0	0

Santa Fe Municipal	100	0	0	0	0

Lovell Field	0	42,182	25,309	25,309	25,309

Aberdeen Regional	100	0	0	0	0

Sacramento International	20	0	0	0	0

Toledo Express	20	383,445	0	93,465	186,929

Portland International	20	911,546	0	222,189	444,379

John Wayne Airport-Orange County	100	0	0	0	0

Juneau International	0	459,700	89,641	179,283	268,924

Nome	0	30,113	5,872	11,744	17,616

Spokane International	100	0	0	0	0

Fort Lauderdale/Hollywood International	NA	0	0	0	0

Pittsburgh International	60	3,931,605	0	0	0

Louisville International-Standiford Field	60	522,149	0	0	0

Airborne Airpark	40	2,331,713	0	0	757,807

Aniak	0	5,540	1,080	2,161	3,241

Port Columbus International	0	3,120,055	608,411	1,216,822	1,825,232

Deadhorse	100	0	0	0	0

Cincinnati/Northern Kentucky International	87	822,345	0	0	0

Stewart International	40	196,863	0	0	63,980

Jacksonville International	100	0	0	0	0

Reno/Tahoe International	20	606,939	0	147,941	295,883

Cherry Capital	100	0	0	0	0

Bethel	0	50,915	9,928	19,857	29,785

Rickenbacker International	0	108,882	21,232	42,464	63,696

Rapid City Regional	0	258,448	50,397	100,795	151,192

Theodore Francis Green State	60	610,460	0	0	0

Southwest Florida International	100	0	0	0	0

James M Cox Dayton International	60	380,946	0	0	0

Des Moines International	40	490,533	0	0	159,423

Sarasota/Bradenton International	NA	0	0	0	0

Minneapolis-St Paul International/Wold-Chamberlain	60	6,362,897	0	0	0

Willow Run	40	62,356	0	0	20,785

Charlotte/Douglas International	0	1,392,605	271,558	543,116	814,674

Bradley International	60	1,778,704	0	0	0

San Antonio International	0	129,604	25,273	50,545	75,818

Wilkes-Barre/Scranton International	0	432,418	84,322	168,643	252,965

Chippewa Valley Regional	100	0	0	0	0

Phoenix Sky Harbor International	20	0	0	0	0

St George Municipal	100	0	0	0	0

Lafayette Regional	0	15,133	9,080	9,080	9,080

General Mitchell International	41	957,716	0	0	308,417

Dallas Love Field	40	227,012	0	0	73,779

Detroit Metropolitan Wayne County	100	0	0	0	0

Philadelphia International	85	1,530,580	0	0	0

Memphis International	0	2,073,854	404,401	808,803	1,213,204

Ronald Reagan Washington National	40	1,309,731	0	0	436,577

Washington Dulles International	40	6,052,151	0	0	1,966,949

San Francisco International	100	0	0	0	0

Central Wisconsin	0	443,467	86,476	172,952	259,428

Newark Liberty Intl	0	11,464,956	2,235,666	4,471,333	6,706,999

Northwest Arkansas Regional	0	312,852	61,006	122,012	183,018

Raleigh-Durham Intl	0	1,041,489	203,090	406,181	609,271

Kansas City Intl	40	1,279,726	0	0	415,911

Fort Worth Alliance	60	6,898	0	0	0

Greater Rockford	60	557,825	0	0	0

Kalamazoo/Battle Creek Intl	60	88,053	0	0	0

Duluth Intl	0	765,304	149,234	298,468	447,703

Akron - Canton Regional	60	255,826	0	0	0

Step 5: Estimate COD reductions associated with discontinued use of urea

	As described above, ERG calculated the COD load associated with urea
use at the surveyed airports. ERG then evaluated the amount of potassium
acetate that would be required to replace the current average urea use
using a comparison of application rates under varying winter conditions
(DCN 00843). Based on the COD load associated with the equivalent
potassium acetate use, ERG determined the potential reductions in COD
load. Table 6 presents the baseline COD load associated with urea, the
estimated equivalent COD load if industry converted from urea to
potassium acetate, and the load reduction.

Table 6. Baseline COD Load and Potential Load Reduction Associated with
the Discontinued Use of Urea as an Airfield Deicing Chemical

Airport ID	Airport	Urea Load

(lbs of COD)	Equivalent Potassium Acetate Load

(lbs of COD)	Potential Load Reduction

(lbs of COD)

1007	Yeager	56,797	15,663	41,133

1010	Fairbanks International	816,961	225,297	591,664

1012	Ted Stevens Anchorage International	3,560,670	981,943	2,578,727

1013	Wiley Post-Will Rogers Mem	42,624	11,755	30,869

1016	Tri - State/Milton J Ferguson Field	133,555	36,831	96,724

1017	Austin Straubel International	88,530	24,414	64,116

1018	Piedmont Triad International	210,279	57,990	152,289

1022	Fort Wayne International	571,082	157,490	413,592

1041	Glacier Park International	710	196	514

1043	Ralph Wien Memorial	21,312	5,877	15,435

1053	General Edward Lawrence Logan International	12,148	3,350	8,798

1066	Salt Lake City International	3,127,198	862,402	2,264,796

1074	South Bend Regional	69,136	19,066	50,070

1079	Manchester	47,952	13,224	34,728

1090	Boise Air Terminal/Gowen Field	864,579	238,429	626,150

1103	Juneau International	1,082,651	298,568	784,083

1105	Spokane International	1,361,128	375,365	985,763

1110	Aniak	5,115	1,411	3,704

1112	Deadhorse	42,624	11,755	30,869

1114	Stewart International	323,516	89,218	234,299

1116	Reno/Tahoe International	15,426	4,254	11,172

1118	Bethel	140,659	38,790	101,869

1128	Charlotte/Douglas International	496,464	136,912	359,551

1129	Bradley International	35,692	9,843	25,849

1141	Ronald Reagan Washington National	133,555	36,831	96,724

1144	Central Wisconsin	179,859	49,601	130,259

1146	Northwest Arkansas Regional	57,542	15,869	41,674

1147	Raleigh - Durham International	190,387	52,504	137,883

1150	Greater Rockford	1,396,079	385,004	1,011,076

1153	Akron - Canton Regional	45,466	12,538	32,927

Step 6: Scale the loading removal estimates up to represent the entire
industry

The EPA Airport Deicing Detailed Questionnaire was sent to a stratified
random sample of airports based on:

Airport type (i.e., hub, non-hub), 

The number of snow or other freezing precipitation (SOFP) days, and 

The number of departures.  

EPA developed weighting factors for each airport that received an
Airport Detailed Questionnaire.  The weighting factor indicates the
number of similar airports that each questionnaire represents.  For
example, if an airport’s weighting factor is five, that airport
represents five other airports that are of a similar size and climate. 
ERG multiplied the direct discharge loads or load removals by the
airport weighting factors to determine National loads for the entire
industry for baseline and each regulatory scenario.  

 Switzenbaum, et al.  1999.  Workshop: Best Practices for Airport
Deicing Stormwater 

Memorandum

April 2008

Page   PAGE  2  of   NUMPAGES  22