2 Printed on paper containing at least 30% postconsumer recovered fiber.
ACKNOWLEDGMENTS AND DISCLAIMER

The Agency would like to acknowledge the contributions of Shari Barash, James Covington III,

and Charles Tamulonis to the development of this Preliminary Data Summary. In addition, EPA

acknowledges the contribution of Eastern Research Group, Inc.

This report on deicing fluids does not set forth any regulatory requirements under the Clean

Water Act. It is intended solely as a presentation of information of which EPA is currently aware

concerning the use of deicing fluids at airports. Thus, it does not impose any requirements on any

party, including EPA, states, permitting authorities, POTWs, or the regulated community. This

report was prepared using information from the following sources: review of selected literature,

reports, and advisories; meetings with several interested parties; personal visitation with several

persons and airport personnel; the experience of the authors; and other information solicited from

stakeholders.

References made in this document to any specific method, product or process, vendor, or

corporation do not constitute or imply an endorsement, recommendation, or warranty by the U.S.

Environmental Protection Agency. The Agency does not assume any legal liability or

responsibility for any third party’s use of, or the results of such use of, any information discussed

in this report, or represents that its use by such a third party would not infringe on privately

owned rights.
i

TABLE OF CONTENTS

Page

1.0 EXECUTIVE SUMMARY .......................................... 1-1

2.0 INTRODUCTION ................................................ 2-1

3.0 DATA-COLLECTION ACTIVITIES .................................... 3-1

3.1 1993 Screener Questionnaire ................................ 3-1

3.2 Mini-Questionnaires ...................................... 3-2

3.2.1 Airport Questionnaire ............................... 3-3

3.2.1.1 Airport Questionnaire Development ......... 3-4

3.2.1.2 Airport Questionnaire Administration ........ 3-4

3.2.2 Vendor Questionnaire ............................... 3-5

3.2.2.1 Vendor Questionnaire Development ......... 3-5

3.2.2.2 Vendor Questionnaire Administration ........ 3-6

3.2.3 POTW Questionnaire ............................... 3-6

3.2.3.1 POTW Questionnaire Development ......... 3-6

3.2.3.2 POTW Questionnaire Administration ........ 3-7

3.3 EPA Site Visits .......................................... 3-7

3.4 EPA Sampling .......................................... 3-9

3.5 Data Submitted by Airports ................................ 3-11

3.6 Meetings with Federal Agencies, Industry Representatives, Trade

Associations, and Technology Vendors ....................... 3-12

3.7 Literature ............................................. 3-13

3.8 Other Data Sources ...................................... 3-14

3.9 References ............................................ 3-15

4.0 TECHNICAL PROFILE ............................................ 4-1

4.1 Air Transportation Industry Overview ......................... 4-1

4.1.1 Airport Types and Sizes ............................. 4-1

4.1.2 Geographic Location of Airports ....................... 4-3

4.1.3 Types of Airlines ................................... 4-4

4.2 Deicing/Anti-Icing Operations ............................... 4-5

4.2.1 Aircraft Deicing/Anti-icing ........................... 4-5

4.2.1.1 Fluid Types ........................... 4-7

4.2.1.2 Fluid Uses ............................ 4-8

4.2.1.3 Fluid Application ...................... 4-10

4.2.1.4 Variables That Affect Fluid Use ........... 4-12

4.2.1.5 Dry-Weather Deicing ................... 4-13

4.2.1.6 Nonchemical Deicing Methods ............ 4-14

4.2.2 Pavement Deicing/Anti-icing ......................... 4-15

4.2.2.1 Mechanical Methods ................... 4-16

4.2.2.2 Chemical Methods ..................... 4-16

4.3 Airports with Deicing/Anti-Icing Operations ................... 4-17
TABLE OF CONTENTS (Continued)

Page

ii

4.3.1 Number of Airports Performing Aircraft and Runway 

Deicing ......................................... 4-17

4.3.1.1 Number of Airports Potentially Performing

Significant Deicing/Anti-Icing Operations .... 4-17

4.3.1.2 Other Estimates of Number of Airports ..... 4-18

4.3.2 Annual ADF and Pavement Deicer Usage ............... 4-19

4.4 References ............................................ 4-23

5.0 CLIMATIC INFLUENCES AND DEICING/ANTI-ICING AGENT-CONTAMINATED STORM

WATER GENERATION AND DISCHARGE .............................. 5-1

5.1 How Climatic Conditions Affect Deicing/Anti-icing Chemical Usage . . 5-1

5.2 Correlating Climatic Conditions to Deicing/Anti-icing Agent Usage . . 5-2

5.2.1 Mean Annual Snowfall .............................. 5-2

5.2.2 Snowfall Duration .................................. 5-3

5.2.3 Mean Annual Days Below Freezing ..................... 5-4

5.2.4 Heating Degree Days ................................ 5-4

5.3 Volume of Contaminated Storm Water Generated ................ 5-4

5.4 Method of Contaminated Storm Water Discharge ................ 5-6

5.5 References ............................................. 5-7

6.0 POLLUTION PREVENTION ......................................... 6-1

6.1 Alternative Aircraft Deicing/Anti-Icing Agents .................. 6-2

6.2 Aircraft Deicing Fluid Minimization Methods ................... 6-3

6.2.1 Type IV Anti-icing Fluids ............................ 6-3

6.2.2 Preventive Anti-icing ................................ 6-4

6.2.3 Forced-Air Aircraft Deicing Systems .................... 6-6

6.2.4 Computer-Controlled Fixed-Gantry Aircraft Deicing Systems . 6-9

6.2.5 Infrared Aircraft Deicing Technology .................. 6-11

6.2.6 Hot Water Aircraft Deicing .......................... 6-16

6.2.7 Varying Glycol Content to Ambient Air Temperature ...... 6-17

6.2.8 Enclosed-Basket Deicing Trucks ...................... 6-18

6.2.9 Mechanical Methods ............................... 6-18

6.2.10 Aircraft Deicing Using Solar Radiation ................. 6-19

6.2.11 Hangar Storage ................................... 6-19

6.2.12 Aircraft Covers ................................... 6-19

6.2.13 Thermal Blankets for MD-80s and DC-9s ............... 6-20

6.2.14 Ice-Detection Systems .............................. 6-21

6.2.15 Airport Traffic Flow Strategies and Departure Slot Allocation

Systems ......................................... 6-22

6.2.16 Personnel Training and Experience .................... 6-23

6.2.17 Other ADF Minimization Practices .................... 6-24
TABLE OF CONTENTS (Continued)

Page

iii

6.2.18 Glycol Minimization Methods Currently Under 

Development ..................................... 6-25

6.3 Aircraft Deicer/Anti-icer Collection and Containment Methods ..... 6-26

6.3.1 Aircraft Deicing Facilities ........................... 6-27

6.3.2 ADF Collection Systems for Ramps and Passenger Terminal Gate

Areas ........................................... 6-31

6.3.3 Temporary Aircraft Deicing Pads ...................... 6-34

6.3.4 Storm Drain Inserts ................................ 6-36

6.3.5 Glycol Vacuum Vehicles ............................ 6-37

6.3.6 Mobile Pumping Station with Fluid Concentration Sensor ... 6-42

6.3.7 Containment and Collection Practices for Snow Contaminated with

Aircraft Deicing/Anti-icing Fluids ..................... 6-44

6.4 Glycol Recycling ........................................ 6-45

6.4.1 Glycol Recyclers .................................. 6-47

6.4.2 Current Uses for Recovered Glycol .................... 6-55

6.4.3 Operational and Economic Issues ..................... 6-56

6.5 Pollution Prevention Practices for Airfield Pavement Deicing/Anti-icing

Operations ............................................ 6-59

6.5.1 Alternative Airfield Pavement Deicing/Anti-icing Agents .... 6-59

6.5.2 Alternative Airfield Pavement Deicing/Anti-icing Methods . . 6-60

6.5.3 Airfield Pavement Deicing/Anti-icing Minimization Practices . 6-61

6.5.3.1 Good Winter Maintenance Practices ........ 6-62

6.5.3.2 Preventive Anti-Icing ................... 6-63

6.5.3.3 Runway Surface Condition Monitoring 

Systems ............................. 6-63

6.6 References ............................................ 6-66

7.0 WASTEWATER CONTAINMENT AND TREATMENT ....................... 7-1

7.1 Wastewater Containment .................................. 7-1

7.2 Wastewater Treatment ................................... 7-10

7.2.1 Biological Treatment ............................... 7-10

7.2.2 Oil/Water Separation ............................... 7-16

7.2.3 Land Application .................................. 7-17

7.3 References ............................................ 7-18

8.0 WASTEWATER CHARACTERIZATION ................................ 8-1

8.1 Industry Self-Monitoring Data .............................. 8-1

8.2 Permit Compliance System (PCS) ............................ 8-7

8.3 EPA Sampling Data ...................................... 8-9

8.3.1 Type I Aircraft Deicing Fluids ........................ 8-10

8.3.2 Characterization of Wastewater from Aircraft Deicing/Anti-icing

Operations ....................................... 8-12
TABLE OF CONTENTS (Continued)

Page

iv

8.3.3 Discussion of Sampling Results ....................... 8-15

8.4 Multi-Sector General Permit Application Data ................. 8-18

9.0 TOXICITY OF DEICING/ANTI-ICING AGENTS ........................... 9-1

9.1 Comparison of Pure Ethylene Glycol to Pure Propylene Glycol ...... 9-2

9.1.1 Aquatic Toxicity ................................... 9-2

9.1.2 Mammalian Toxicity ................................ 9-4

9.1.2.1 Inhalation Exposure ..................... 9-5

9.1.2.2 Oral Exposure ......................... 9-6

9.1.2.3 Dermal Exposure ....................... 9-7

9.2 Toxicity of Additives and Formulated Aircraft Deicing/Anti-Icing Fluids

(ADF) ................................................. 9-9

9.2.1 Aircraft Deicing Fluid Components .................... 9-10

9.2.1.1 Glycol .............................. 9-11

9.2.1.2 Surfactants ........................... 9-11

9.2.1.3 Corrosion Inhibitors and Flame Retardants ... 9-12

9.2.1.4 pH Buffers ........................... 9-13

9.2.1.5 Colorants or Dyes ..................... 9-14

9.2.1.6 1,4-Dioxane .......................... 9-14

9.2.2 Aquatic Toxicity Data for ADF ....................... 9-14

9.2.3 Mammalian Toxicity Data for Aircraft Deicing Fluids ...... 9-18

9.3 Toxicity of Other Freezing-Point Depressants .................. 9-18

9.3.1 Diethylene Glycol ................................. 9-19

9.3.2 Isopropyl Alcohol (Isopropanol) ...................... 9-20

9.4 Toxicity of Pavement Deicers .............................. 9-22

9.4.1 Urea ........................................... 9-22

9.4.2 Ethylene Glycol ................................... 9-25

9.4.3 Potassium Acetate ................................. 9-25

9.4.4 Calcium Magnesium Acetate (CMA) ................... 9-26

9.4.5 Sodium Acetate ................................... 9-27

9.4.6 Sodium Formate .................................. 9-28

9.4.7 Alternative Pavement Deicers ........................ 9-29

9.4.8 Chlorides ........................................ 9-29

9.4.9 Sand ........................................... 9-29

9.5 References ............................................ 9-30

10.0 ENVIRONMENTAL IMPACTS FROM THE DISCHARGE OF DEICING/ANTI-ICING AGENTCONTAMINATED STORM WATER .................................. 10-1

10.1 Degradability and Environmental Fate of Deicing/Anti-icing Agents . 10-2

10.1.1 Ethylene Glycol and Propylene Glycol .................. 10-2

10.1.2 Formulated Aircraft Deicing/Anti-icing Fluids ............ 10-6

10.1.3 Alternative Freezing-Point Depressants ................ 10-10
TABLE OF CONTENTS (Continued)

Page

v

10.1.4 Pavement Deicers ................................ 10-13

10.2 Reports of Environmental Impacts from Airport Deicing Operations 10-15

10.3 Effect on POTWs ...................................... 10-17

10.3.1 EPA POTW Questionnaires ......................... 10-18

10.3.1.1 Chemicals Typically Found in Discharges ... 10-18

10.3.1.2 Contribution of Wastewater Containing

Deicing/Anti-Icing Chemicals to POTWs ... 10-18

10.3.1.3 Documented Negative Impacts at POTWs . . 10-19

10.3.1.4 Documented Positive Impacts ............ 10-21

10.3.2 Evidence of POTW Pass-Through .................... 10-21

10.4 References ........................................... 10-23

11.0 POLLUTANT LOADINGS AND COSTS TO MANAGE WASTEWATER FROM AIRPORT

DEICING OPERATIONS .......................................... 11-1

11.1 Pollutant Loading Estimates ............................... 11-2

11.1.1 Airport Groups (Step 1) ............................ 11-3

11.1.2 Fluid Use Estimates (Step 2) ......................... 11-3

11.1.3 Estimated Annual Volume of Fluid That Has the Potential to

Impact U.S. Surface Waters and POTWs (Step 3) ........ 11-6

11.1.4 Estimated Annual Volume of Aircraft Deicing/Anti-icing Fluid

Discharged Prior to the Implementation of EPA’s Phase I Storm

Water Permit Application Regulations (Step 4) ........... 11-6

11.1.5 Estimated Annual Volume of Aircraft Deicing/Anti-icing Fluid

Currently Discharged (Step 5) ........................ 11-7

11.1.6 Estimated Annual Volume of Aircraft Deicing/Anti-icing Fluid

Discharged to U.S. Surface Waters After Implementation of an

Effluent Guideline (Step 6) .......................... 11-9

11.1.7 Pollutant Loading Estimates ........................ 11-10

11.2 Costs to Manage Wastewater from Airport Deicing Operations .... 11-11

11.3 References ........................................... 11-12

12.0 TRENDS IN THE INDUSTRY ....................................... 12-1

12.1 Trends in the Use of Aircraft Deicing/Anti-icing Fluids ........... 12-1

12.2 Trends in the Use of Airport Pavement Deicing/Anti-icing Agents ... 12-6

12.3 Trends in Deicing/Anti-icing Equipment and Operations .......... 12-7

12.4 Trends in Spent Deicing/Anti-icing Chemical Mitigation ......... 12-8 

12.5 References ........................................... 12-10

13.0 RELATIONSHIP TO OTHER REGULATIONS ............................ 13-1

13.1 EPA Storm Water Program ................................ 13-1

13.1.1 Storm Water Permit Application Regulations ............. 13-2

13.1.2 General Permit (Baseline Industrial General Permit) ........ 13-4
TABLE OF CONTENTS (Continued)

Page

vi

13.1.3 Multi-Sector General Permit ......................... 13-6

13.1.4 Individual Permit ................................. 13-9 

13.2 National, State, and Local Limitations ....................... 13-11

13.2.1 National Regulations .............................. 13-11

13.2.2 State and Local Regulations ........................ 13-12

13.3 Canadian Management Measures .......................... 13-15

13.3.1 Canadian Environmental Protection Act (CEPA) ......... 13-16

13.3.2 Canadian Water Quality Guidelines ................... 13-18

13.4 Federal Aviation Administration Regulations .................. 13-20

13.4.1 FAA Winter Operating Regulations for Aircraft .......... 13-20

13.4.2 FAA Winter Operating Regulations for Airports ......... 13-22

13.5 Society of Automotive Engineers (SAE) Standards for Aircraft

Deicing/Anti-Icing Operations ............................. 13-24

13.5.1 SAE G-12 Committee ............................. 13-24

13.5.2 SAE Standards and Certification for Aircraft Deicing/Anti-icing

Fluids ......................................... 13-25

13.5.3 SAE Environmental Information Requirements .......... 13-26

13.6 References ........................................... 13-28

14.0 ECONOMIC PROFILE ........................................... 14-1

14.1 Airports .............................................. 14-1

14.1.1 Determining the Number, Sizes, and Locations of Airports . . 14-1

14.1.1.1 FAA Airport Size Classifications .......... 14-1

14.1.1.2 Airports with Potentially Significant Deicing/AntiIcing Operations ....................... 14-6

14.1.1.3 Analytic Issues and Evaluation of Data 

Availability .......................... 14-9 

14.1.2 Airport Financial Management and Accounting .......... 14-10

14.1.2.1 Overview ........................... 14-10

14.1.2.2 Airport Financial Data ................. 14-13

14.1.2.3 Analytic Issues and Evaluation of Data 

Availability .......................... 14-15

14.1.3 Airport Ownership and Management .................. 14-18

14.1.3.1 Overview ........................... 14-18

14.1.3.2 Analytic Issues and Evaluation of Data 

Availability .......................... 14-20

14.1.4 Financing Capital Improvements ..................... 14-20

14.1.4.1 Overview ........................... 14-20

14.1.4.2 Analytic Issues and Evaluation of Data 

Availability .......................... 14-24

14.2 Airlines .............................................. 14-25

14.2.1 Types of Air Carriers .............................. 14-25
TABLE OF CONTENTS (Continued)

Page

vii

14.2.1.1 Overview ........................... 14-25

14.2.1.2 Data Availability ...................... 14-28

14.2.2 Air Carrier Finances .............................. 14-29

14.2.2.1 Overview ........................... 14-29

14.2.2.2 Data Availability ...................... 14-33

14.2.3 Airline Deicing Costs .............................. 14-34

14.2.4 Air Transportation Industry Trends ................... 14-37

14.2.4.1 Projected Industry Growth .............. 14-37

14.2.4.2 Regional Jets ........................ 14-38

14.2.4.3 Free Flight .......................... 14-39

14.2.4.4 Competitive Issues .................... 14-40

14.2.5 Analytic Issues .................................. 14-43

14.2.5.1 Assessing Potential Regulatory Impacts .... 14-43

14.2.5.2 Airline-to-Passenger Cost Pass-Through .... 14-47

14.2.5.3 Incentives ........................... 14-49

14.3 References ........................................... 14-50

15.0 GLOSSARY .................................................. 15-1

Appendix A: SELECT U.S. AIRPORT LOCATIONS

Appendix B: MEAN ANNUAL SNOWFALL (THROUGH 1995) FOR SELECT U.S. CITIES

Appendix C: CLIMATE CONTOUR MAP OF THE U.S.

Appendix D: SELECTED FINANCIAL AND SCHEDULED SERVICE TRAFFIC

STATISTICS
viii

LIST OF TABLES

Page

3-1 Summary of Data Submitted by Airports ........................... 3-16

7-1 Summary of Wastewater Containment and Treatment at Airports ......... 7-19

8-1 Summary of Storm Water Monitoring Data from Bradley International 

Airport ..................................................... 8-19

8-2 Summary of PCS Data for Airports with EPA-Estimated Potentially Significant

Deicing/Anti-Icing Operations ................................... 8-21

8-3 Standard Analytical Methods for Parameters Included in EPA’s Airport Deicing

Sampling Program ............................................ 8-25

8-4 Analytical Results for Analytes Detected in Type I Aircraft Deicing Fluids (50%

Solution), Raw Wastewater from Airport Deicing/Anti-Icing Operations, and a

Stormwater Outfall EPA Sampling Data ............................ 8-26

8-5 Analytical and Toxicity Data Provided by Fluid Formulators for Type I Aircraft

Deicing Fluids ............................................... 8-29

9-1 Acute and Chronic Toxicity Data for Pure Glycols for Aquatic Species ..... 9-37

9-2 Additional Acute and Chronic Toxicity Data Sources for Pure Glycols ..... 9-40

9-3 Human Toxicity Data for Pure Ethylene Glycol and Propylene Glycol ...... 9-42

9-4 Acute Toxicity Data for Type I and II Formulated Fluids ............... 9-45

9-5 Additional Aquatic Toxicity Data Sources for Formulated Fluids ......... 9-47

9-6 Aquatic Toxicity Results for Formulated Fluids and Their Components .... 9-48

9-7 Aquatic Toxicity Data for Diethylene Glycol ........................ 9-50

9-8 Mammalian Toxicity Data for Diethylene Glycol ...................... 9-52

9-9 Aquatic Toxicity Data for Isopropanol ............................. 9-53

9-10 Mammalian Toxicity Data for Isopropanol .......................... 9-54
LIST OF TABLES (Continued)

Page

ix

10-1 Ultimate BOD Values for Pure Ethylene Glycol and Propylene Glycol Acclimated

Sludge Seeds ............................................... 10-25

10-2 Biological Degradation Results for Diethylene Glycol ................. 10-27

10-3 Reported Environmental Impacts from Airport Deicing Operations ....... 10-28

11-1 Capital Costs Incurred by Airports for Management of Wastewater from Airport

Deicing Operations ........................................... 11-13

11-2 Annual Costs Incurred by Airports for Management of Wastewater from Airport

Deicing Operations ........................................... 11-16

13-1 Airport Permit Data for ADF-Contaminated Wastewater .............. 13-29

13-2 Summary of Available Permit Data ............................... 13-35

14-1 Passenger and Cargo Activity by FAA Airport Definition, 1997 ......... 14-55

14-2 Growth of Total and Average Enplanements at Commercial Service Airports by

FAA Definition, 1993 - 1997 ................................... 14-56

14-3 Airport Flight Operations by FAA Airport Definition, 1997 ............ 14-57

14-4 Airports of Concern, by Operations, Snowfall, and FAA Size 

Definitions (a) .............................................. 14-58

14-5 Airports with Potentially Significant Deicing Operations, by Operations and

Enplanements (a) ............................................ 14-59

14-6 Airport Operating Agreements by Airport Type AAAE Survey Respondents, 

1997 - 1998 ................................................ 14-60

14-7 Airport Revenues by Airport Type for AAAE Survey Respondents, 

1997 - 1998 ................................................ 14-61

14-8 Airport Expenditures for EPA Airport Mini-Questionnaire Recipients, 

1997 ...................................................... 14-62

14-9 Airport Ownership by Airport Type AAAE Survey Respondents, 

1997 - 1998 ................................................ 14-63
LIST OF TABLES (Continued)

Page

x

14-10 Airport Capital Expenditures for EPA Airport Minisurvey Recipients, 

1997 ...................................................... 14-64

14-11 Aircraft in Operation, Hours Flown, and Hours per Aircraft, Selected Aircraft

Type, U.S. Air Carriers, and General Aviation, 1996 ................. 14-65

14-12 Air-Carrier Traffic Statistics by Carrier Type, June 1997 - June 1998 ..... 14-66

14-13 Air-Carrier Financial Statistics by Carrier Type, June 1997 - June 1998 ... 14-67

14-14 Passenger and Cargo Revenues for ATA Member Airlines, 1997 

(x $1,000,000) .............................................. 14-68

14-15 Operating Revenues, Expenses, and Profits, 1982 - 1997 (in millions of 

dollars) .................................................... 14-69

14-16 Airline Operating Costs, Selected Components, 1982 - 1997 ........... 14-70

14-17 Estimated Deicing Costs and Weather Conditions at 5 Selected Airports . . 14-72

14-18 National Estimate of Total Deicing Costs at US Airports, 1997 - 1998 .... 14-73
xi

LIST OF FIGURES

Page

4-1 Geographic Distribution of Airports with Annual Operations Greater than 

10,000 and Mean Annual Snowfall Greater than 1 Inch ................. 4-25
Section 1.0 - Executive Summary

1-1

1.0 EXECUTIVE SUMMARY

The deicing and anti-icing of aircraft and airfield surfaces is required by the Federal

Aviation Administration (FAA) to ensure the safety of passengers; however, when performed

without discharge controls in place, airport deicing operations can result in environmental

impacts. In addition to potential aquatic life and human health impacts from the toxicity of

deicing and anti-icing chemicals, the biodegradation of propylene or ethylene glycol (i.e., the base

chemical of deicing fluid) in surface waters (i.e., lakes, rivers) can greatly impact water quality,

including significant reduction in dissolved oxygen (DO) levels. Reduced DO levels can

ultimately lead to fish kills.

This Preliminary Data Summary provides information about the air transportation

industry and the best practices being employed for aircraft and airfield deicing operations, as well

as for the collection, containment, recovery, and treatment of wastewaters containing deicing

agents. This study was conducted to meet the obligations of the EPA under Section 304(m) of

the Clean Water Act, in accordance with the consent decree in Natural Resources Defense

Council and Public Citizen, Inc. v. Browner (D.D.C. 89-2980, as modified February 4, 1997). 

EPA hopes that this study will serve as an objective source of information that can be used by

airports, airlines, state and local regulators, and citizen groups. 

Deicing involves the removal of frost, snow, or ice from aircraft surfaces or from

paved areas including runways, taxiways, and gate areas. Anti-icing refers to the prevention of

the accumulation of frost, snow, or ice on these same surfaces. Deicing and anti-icing operations

can be performed by using mechanical means (e.g., brooms, brushes, plows) and through the

application of chemical agents. Typically, airlines and fixed-base operators (i.e., contract service

providers) are responsible for aircraft deicing/anti-icing operations, while airports are responsible

for the deicing/anti-icing of airfield pavement. Although compliance with environmental

regulations and requirements associated with deicing/anti-icing operations may be shared between

the airlines/fixed-base operators and the airports (e.g., airport authority) as co-permittees, the
Section 1.0 - Executive Summary

 General Aviation (GA) operations are the portion of civil (i.e., non-military) aviation which encompasses all facets of 1

aviation except air carriers (e.g., passenger and cargo airlines). 

1-2

airport is ultimately responsible for the management of the wastewater that is generated. This

responsibility is typically outlined in the airport’s discharge permit.

Deicing/anti-icing operations are typically performed from October through May at

many of the nation’s airports. Although low DO levels are less likely to occur during the coldest

period of the deicing season, as the season ends and temperatures rise, airports are still

conducting deicing operations. In addition, the snow dump piles containing deicing agents melt, 

releasing chemicals into receiving streams. EPA believes that more information is necessary to

fully determine the effect of temperature on the reduction of DO in receiving streams caused by

the biodegradation of deicing chemicals. However, EPA believes that there has been evidence

that impacts could occur in some regions throughout much of the deicing season. For example,

during past deicing seasons, airports experienced fish kills caused by their discharges. This may

be due to reduced DO levels or the aquatic toxicity of the deicing chemicals.

For the purposes of this study, EPA focused on approximately 200 U.S. airports

with potentially significant deicing/anti-icing operations. Such airports receive a minimum of one

inch, on average, of snowfall annually and conduct at least 10,000 operations (i.e., aircraft takeoffs or landings) annually, excluding general aviation operations. These airports are very diverse 1

in terms of climate, location, existing infrastructure, size, type and mix of tenants, resources, and

ownership structure. EPA collected technical and economic information on these airports from a

variety of sources including: industry questionnaires, site and sampling visits, meetings with

industry and regulatory agencies, and literature. In addition, the study includes information that

may be applicable to airport deicing operations and the management of associated wastewaters

from the U.S. military and from airports in Canada and Europe.

The Phase I Storm Water Discharge Permit regulations specifically cover the direct

discharge of deicing agent contaminated storm water from airports into the nation’s surface
Section 1.0 - Executive Summary

1-3

waters. Although these regulations were developed by EPA, they are implemented, in most cases,

by individual states. When developing individual airport storm water discharge permits, states

may take into account local water quality issues. This leads to a large disparity in permit

requirements from airport to airport. EPA found that the airports that have accomplished the

most in terms of wastewater collection, containment, and recycling/treatment programs were most

likely to be striving to comply with stringent storm water discharge permits. EPA finds that, on

average, these airports have achieved 70% collection efficiency of the aircraft deicing/anti-icing

fluids applied. They have also spent an average of nearly $20 million, over a period of several

years, to finance the necessary equipment and infrastructure changes. EPA notes that since the

implementation of EPA’s Storm Water Discharge Permit regulations and the resulting increase in

the use of best management practices, fewer severe environmental incidents have been reported. 

Specific pollutant control practices and technologies implemented at a specific

airport are dependent on a variety of factors such as climate, existing infrastructure, cost, and

state and local environmental regulations. However, in general, EPA found the following trends

among U.S. airports:

C Increased use of propylene glycol-based aircraft deicing fluids over use of

ethylene glycol-based fluids;

C Increased use of anti-icing fluids as a means of reducing the volumes of

deicing fluid needed;

C Increased efforts by the industry to procure fluids with additives that are

less toxic to aquatic life;

C Increased use of alternative airfield pavement deicing chemicals, such as

potassium acetate, as a replacement for urea or ethylene glycol-based

pavement deicers;

C Increased acceptance and commercial use of source reduction technologies

(e.g., forced air and infra-red deicing equipment) used in combination with

traditional methods for aircraft deicing;

C Increased use of systems for glycol recycling/recovery from spent aircraft

deicing fluid; and
Section 1.0 - Executive Summary

1-4

C Increased use of collection, containment, and treatment (on-site or off-site

at the Publicly Owned Treatment Works (POTW)).

In addition, more technology vendors are supplying the industry with the equipment and contract

management services for containment, collection, recycling/recovery, and treatment technologies. 

This healthy competition has reduced the costs of these technologies and contract services and

made them feasible at some small to medium-size airports.

As part of this study EPA has developed estimates of pollutant loadings to the

environment from airport deicing operations. EPA estimates that prior to the implementation of

the Phase I Storm Water Discharge Permit regulations (pre-1990) the industry discharged

approximately 28 million gallons (50% concentration) of aircraft deicing fluid (ADF) annually to

surface waters. This equates to annual discharges of approximately: 14 million gallons of ADF

concentrate (prior to dilution with water for application); 12.6 million gallons of pure glycols; or

approximately 100 million pounds of BOD .5

EPA estimates that, due to the best management practices put into place under the

storm water permit regulations, current discharges are 21 million gallons of ADF (50%

concentration) per year to surface waters with an additional 2 million gallons discharged to

POTWs. EPA estimates that this will be further reduced to less than 17 million gallons of ADF

(50% concentration) per year discharged to surface waters when the requirements of all airport

storm water permits are fully implemented. The volume discharged to POTWs is expected to

steadily increase. 

Finally, EPA estimated possible reductions in discharges of ADF if effluent

limitations guidelines and standards were implemented for airport deicing operations. Assuming

that all airports with potentially significant deicing operations could achieve a 70% collection

efficiency of ADF applied, EPA estimates that discharges to surface waters from airport deicing

operations could be reduced to approximately 4 million gallons ADF (50% concentration) per

year (approximately 12.5 million pounds BOD5 per year). This would likely result in greatly
Section 1.0 - Executive Summary

1-5

increased volumes discharged to POTWs, as well as an increase in the use of source reduction

technologies, recycling/recovery and treatment systems. In addition, FAA projects that the

demand for air transportation services will continue to grow. This may result in increased airport

deicing and anti-icing operations. However, with the implementation of pollution control 

practices and technologies, industry growth may not result in an increase in deicing/anti-icing

chemicals discharged to the environment.

EPA believes that most POTWs are equipped to handle discharges from airport

deicing/anti-icing operations. However, based on a survey of POTWs that currently accept such

discharges, airports must control the flow and the BOD loading discharged to the POTW. Most

airports use a combination of wastewater storage and controlled discharge to avoid discharging a

“slug-dose” of deicing agent contaminated wastewater to the POTW. In addition, because

deicing discharges are seasonal, the airports must slowly “ramp-up” (or acclimate) the POTW at

the beginning of each deicing season to avoid an upset.

The economic conditions of the air transportation industry are complex in nature. 

For the purposes of the study, EPA collected information on airport financial management and

ownership structures as well as air carrier (i.e., airline) finances to provide an economic overview

of the industry. Airport ownership structures are varied (e.g., public v. private, city council v.

independent authority) and lead to the use of different financial accounting practices between

airports. In many cases, much of the cost of capital improvements are likely to be passed-through

to the airlines as higher fees or to the passenger in the form of passenger facility charges (PFCs). 

Airlines, generally, operate with low profit margin and may also pass costs through to the

passenger in the form of higher ticket prices for certain routes. EPA found that the largest cost to

the airlines associated with aircraft deicing was the cost of delaying departure of the aircraft. 

Therefore, the airlines have a great interest in providing input on the various approaches that an

airport may consider when trying to control discharges from airport deicing operations. For

instance, depending on an airport’s runway and taxiway configuration, the use of centralized

deicing pads may potentially create or reduce departure delays. However, the greatest potential

economic impact to the industry from implementing capital improvements to reduce discharges
Section 1.0 - Executive Summary

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from airport deicing operations may be a reduction of quality or frequency of service to airports

that do not serve large cities (i.e., smaller airports). For example, an airline may choose to

operate less flights per day into a particular airport or to operate smaller aircraft on that route. 

For this reason, EPA believes the collection of airline route-specific data may be necessary to

perform a full analysis of the industry’s economic and financial condition.
Section 2.0 - Introduction

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2.0 INTRODUCTION

The U.S. Environmental Protection Agency (EPA) is required by Section 301(d)

of the Federal Water Pollution Control Act Amendments of 1972 and 1977 (the “Act”) to review

and revise every five years, if appropriate, effluent limitations promulgated pursuant to Sections

301, 304, and 306. Effluent limitations guidelines and standards (or “effluent guidelines”) are

technology-based national standards that are developed by EPA on an industry-by-industry basis,

and are intended to represent the greatest pollutant reductions that are economically achievable

for an industry. These limits are applied uniformly to facilities within the industry scope defined

by the regulations regardless of the condition of the water body receiving the discharge. To

address variations inherent in certain industries, different numeric limitations may be set for

groups of facilities (i.e., subcategories) within the industry based on their fundamental differences,

such as manufacturing processes, products, water use, or wastewater pollutant loadings. The

limits and standards that are developed are used by permit writers and control authorities (e.g.,

Publicly Owned Treatment Works or “POTW”) to write wastewater discharge permits. The

permits may be more stringent due to water quality considerations but may not be less stringent

than the national effluent guidelines. EPA has issued national technology-based effluent

guidelines for over 50 industries. 

EPA conducted a study of airport deicing operations (the Study) to collect

engineering, economic, and environmental data for use in determining whether national

categorical effluent limitations guidelines and standards should be developed for this category of

dischargers. A secondary purpose of the Study was to provide information to permit writers,

control authorities, airports, and airlines in developing pollutant control strategies for discharges

from airport deicing operations. EPA was required to conduct the Study under Section 304(m) of

the Clean Water Act (CWA), in accordance with a consent decree in Natural Resources Defense

Council and Public Citizen, Inc. v. Browner (D.D.C. 89-2980, as modified February 4, 1997). 

The consent decree required that EPA, at a minimum, address the following:
Section 2.0 - Introduction

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“a. The effectiveness of the current storm water permitting system and the

comparative effectiveness of an effluent guideline approach;

b. A characterization of wastewater from deicing operations in terms of

pollutant concentrations, volumes, and environmental impacts; 

c. The feasibility and effectiveness (in different geographic regions) of various

deicing material management technology including complete capture or

recycling, product substitution (e.g., propylene glycol for ethylene glycol),

and alternative deicing methods (e.g., infrared heating);

d. For each technology, management measure or maintenance activity

examined, the types of appropriate numeric or otherwise objective

measurable goals, surrogate indicators, performance measures, or

operation or design criteria (including zero discharge) that have been or

could be effectively employed;

e. The cost and cost minimization opportunities of deicing material

management; and

f. The status and trends of deicing chemical use in the airport industry and in

the development and use of prevention and treatment technologies.”

EPA collected and reviewed data from numerous sources to fulfill the

requirements of the consent decree and to increase its understanding of technical, economic, and

environmental issues related to airport deicing operations. Technical issues include: aircraft,

runway, and taxiway deicing processes; deicing equipment; wastewater generation; wastewater

collection, and handling; and pollution prevention/treatment technologies. Economic issues

include significant economic and financial aspects of the air transportation industry (i.e., airports

and airlines). Environmental issues include impacts from discharges of storm water contaminated

with deicing/anti-icing chemicals. 

This document discusses the Agency’s findings about whether regulatory

development of national categorical effluent limitations guidelines and standards should be

undertaken for this category of dischargers and to meet the objectives of the consent decree. The

document describes data-collection activities (Section 3.0), a technical profile of the industry

(Section 4.0), climatic influences and deicing/anti-icing agent- contaminated storm water
Section 2.0 - Introduction

2-3

generation and discharge (Section 5.0), pollution prevention opportunities (Section 6.0),

wastewater collection, treatment, and disposal (Section 7.0), and wastewater characterization

(Section 8.0). This document also discusses the toxicity of deicing/anti-icing fluids (Section 9.0),

provides an environmental assessment of the impacts associated with airport deicing/anti-icing

(Section 10.0), and provides estimated pollutant load removals and costs to manage wastewater

from deicing operations (Section 11.0). Trends in the industry (Section 12.0), the relationship a

national effluent guideline would have to other regulations (Section 13.0), and an economic

profile of the industry and facility economic data (Section 14.0) are also included. A glossary of

frequently used terms and acronyms is also included (Section 15.0). 
Section 3.0 - Data-Collection Activities

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3.0 DATA-COLLECTION ACTIVITIES

EPA collected data from a variety of sources, including existing data from

previous EPA and other governmental data-collection efforts, industry-provided information, data

collected from questionnaire surveys, and site visit and sampling data. Each of these data sources

is discussed below, as well as the quality assurance/quality control (QA/QC) and other dataediting procedures. Summaries and analyses of the data collected by EPA are presented in the

remainder of this document.

Sections 3.1 and 3.2 describe EPA’s 1993 screen questionnaire and EPA’s miniquestionnaires, respectively. Section 3.3 discusses EPA site visits and Section 3.4 discusses EPA

sampling. Data submitted by airports is presented in Section 3.5, and Section 3.6 discusses

meetings with various interested parties. Finally, Section 3.7 discusses technical literature,

Section 3.8 discusses other data sources, and Section 3.9 presents the references for the section. 

Appendix A contains information regarding the location of airports referenced in this section.

3.1 1993 Screener Questionnaire

In 1992, EPA began developing effluent limitations guidelines and standards for

the Transportation Equipment Cleaning Industry (TECI). The scope of the TECI regulation at

that time included: facilities that clean the interiors of tank trucks, rail tank cars, and tank barges;

facilities that clean aircraft exteriors; and facilities that deice/anti-ice aircraft and/or pavement. 

Initial data-collection efforts for this program related to airport deicing operations included

development and administration of a screener questionnaire, the U.S. Environmental Protection

Agency Aircraft and Pavement Screener Questionnaire administered in 1993. The screener

questionnaire was developed, in part, to enable EPA to: (1) identify facilities that perform TECIAircraft operations; (2) evaluate facilities based on wastewater, economic, and operational

characteristics; and (3) develop technical and economic profiles of the industry. Subsequent to

distribution of the screener questionnaire, EPA decided not to include the aircraft segment as part

of the TECI effluent guideline as a result of a revision to the EPA’s storm water program that
Section 3.0 - Data-Collection Activities

3-2

required storm water permits to address wastewater discharges from these practices (EPA’s storm

water program is discussed in Section 13.1) and an assessment that this segment’s activities were

significantly different than other TECI segments’ activities.

Facilities chosen to receive a screener questionnaire were selected from the

Aircraft Site Identification Database (a subset of the TECI Site Identification Database). This

database contained information for 3,957 facilities that potentially perform aircraft exterior

cleaning and/or aircraft or pavement deicing/anti-icing operations (e.g., airlines and fixed based

operators (FBOs)). Facilities listed in the database were a stratified random sample of the 4,778

facilities that compose the total potential industry population. EPA mailed the screener

questionnaire to a statistical random sample of 760 facilities that potentially perform aircraft

exterior cleaning and/or aircraft or pavement deicing/anti-icing operations (TECI-Aircraft

operations). 

Following the screener questionnaire mailout and analyses of responses, EPA

estimated that, in 1993, there were 588 facilities (i.e., airlines and FBOs) that perform

deicing/anti-icing operations. For the purposes of this Study, EPA used responses from facilities

that perform deicing/anti-icing operations to develop a technical profile of the industry and to

identify trends in the industry. Additional details concerning the 1993 screener questionnaire are

presented in a report entitled Development of Survey Weights for the U.S. Environmental

Protection Agency Aircraft and Pavement Screener Questionnaire (1). 

3.2 Mini-Questionnaires

To collect more detailed and current information, albeit from fewer facilities, EPA

mailed mini-questionnaires to various industry representatives and other interested parties. Due

to Paperwork Reduction Act concerns, EPA selected only a small portion of the industry (major

and regional airports and airlines, technology vendors, and POTWs) to receive a questionnaire. 

Airlines were asked to submit only financial data, while airports were asked to submit financial

and technical information. Technology vendors and POTWs were asked to provide only technical
Section 3.0 - Data-Collection Activities

3-3

information. The Air Transport Association (ATA) provided one collective questionnaire

response for the 12 major carriers while eight regional airlines were each sent questionnaires. See

Section 14.0 for additional information on the airline questionnaires.

EPA selected a technically representative group of recipients based on a set of

selection criteria for each questionnaire type. EPA requested data through the 1998-1999 deicing

season to obtain the most up-to-date data available from the industry. The data are used to

describe and characterize the industry, and estimate current and projected pollutant discharge

loadings from the industry. Unlike the 1993 screener questionnaire, the mini- questionnaires are

not considered a statistical survey of the industry. The report entitled Methodology for Selection

of Mini-Questionnaire Recipients (2) describes EPA’s selection methodology and presents

questionnaire recipients. These mini-questionnaires are discussed in more detail in Sections 3.2.1

through 3.2.3.

3.2.1 Airport Questionnaire

The airport questionnaire requests information from airports regarding aircraft and

airfield pavement deicing and anti-icing activities performed at an airport and associated

wastewater handling and treatment, in addition to airport structure, finances, and operations. 

EPA used two primary criteria to select airport mini-questionnaire recipients: airport size and

mean annual snowfall. Airport size groupings and mean annual snowfall groupings were defined

independently, and then combined to form airport categories. EPA identified data gaps by first

identifying categories for which data are already available via EPA-sponsored site visits (see

Section 3.3), and then determining which categories require data, or additional data, through

questionnaires. EPA selected nine airports that represent airport categories for which little or no

data were available to complete a questionnaire.
Section 3.0 - Data-Collection Activities

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3.2.1.1 Airport Questionnaire Development

EPA sent a draft version of the questionnaire to representatives from two industry

trade associations (American Association of Airport Executives (AAAE) and the Airport Council

International - North America (ACI-NA)) for review and comment. Comments from AAAE and

ACI-NA were incorporated into the final version of the questionnaire.

The questionnaire included two parts:

1. Part A: Technical Information

- Section 1: General Information,

- Section 2: Airfield Pavement Deicing/Anti-icing Operations,

- Section 3: Aircraft Deicing/Anti-icing Operations,

- Section 4: Aircraft and Pavement Deicing/Anti-icing Fluid

Collection, Treatment, and Disposal; and

2. Part B: Airport Structure, Finances, and Operations.

Part A requested technical information concerning deicing operations at airports. 

Information was used to develop an industry profile and estimate pollutant discharge loadings

from airfield pavement and aircraft deicers/anti-icers. Part A also requested information regarding

deicing chemical collection, disposal, and treatment practices, which was used to identify and

evaluate applicable pollution prevention and wastewater collection and treatment techniques

available to the industry. Part B requested information necessary to develop a general industry

economic profile (see Section 14.0 for additional information).

3.2.1.2 Airport Questionnaire Administration

EPA mailed the airport questionnaire in June 1999 to nine selected airports. One

airport voluntarily submitted a questionnaire. The Agency completed a detailed engineering

review of the questionnaires and contacted by telephone respondents who provided incomplete or

contradictory technical information. The information gathered from the questionnaires was
Section 3.0 - Data-Collection Activities

3-5

entered into EPA’s Airport Matrix, a database that contains information on all aspects of airfield

pavement and aircraft deicing for the airports for which detailed information is available (via EPA

site visits or the questionnaires). The Airport Matrix was used to characterize the industry,

validate EPA’s snowfall and operations groups, and estimate baseline pollutant loadings

discharged to U.S. surface waters and to POTWs.

3.2.2 Vendor Questionnaire

Vendors that received a questionnaire included manufacturers, businesses, and

operators of equipment used to collect, control, recycle/recover, treat, or reduce the generation of

glycol-contaminated wastewater from aircraft and airfield pavement deicing and anti-icing. EPA

identified nine vendors that specialize in certain aspects of these areas based on information

obtained during engineering site visits to airports and meetings with industry representatives. In

general, EPA selected vendors for which little or no data were previously available.

3.2.2.1 Vendor Questionnaire Development

A draft version of the questionnaire was sent to one treatment technology vendor, 

Inland Technologies, Inc. (Inland), for review and comment. Comments from Inland were

incorporated into the final version of the questionnaire. The questionnaire was divided into the

following sections:

C Section 1: General Information;

C Section 2: Information on Specific Equipment and Services;

C Section 3: Rates and Charges;

C Section 4: Future Operations;

C Section 5: Wastewater Treatment and Recycling/Recovery;

C Section 6: Process Influent and Effluent;

C Section 7: Residuals and Solid Waste; and

C Section 8: Additional Information.
Section 3.0 - Data-Collection Activities

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The questionnaire requested information necessary to identify and characterize the

types of equipment manufactured, leased, or operated by the vendor. The questionnaire also

requested information necessary to assess costs to the industry for operating the equipment and to

further characterize wastewater treatment and recycling/recovery operations. 

3.2.2.2 Vendor Questionnaire Administration

The vendor questionnaire was mailed in June 1999 to nine selected vendors and

one Canadian vendor. The Agency completed a detailed engineering review of the questionnaires

and contacted by telephone respondents who provided incomplete or contradictory technical

information. The information gathered from the questionnaires was summarized in a report and

was used to provide costs for managing wastewater from airport deicing operations. 

3.2.3 POTW Questionnaire

EPA developed the POTW questionnaire to obtain information from POTWs that

accept or have accepted wastewaters containing airport deicing chemicals. EPA selected POTW

questionnaire recipients based on the general characteristics of the discharges they receive or once

received (e.g., receive discharges of all aircraft deicing/anti-icing agent-contaminated wastewater,

receive discharges of only low-strength agent-contaminated wastewater). EPA obtained

information regarding POTWs from EPA site visits, discussions with airport, airline, and POTW

trade association members, discussions with treatment technology vendors, and literature and

newspaper searches. 

3.2.3.1 POTW Questionnaire Development

A draft version of the questionnaire was sent to a representative for the

Metropolitan Water Reclamation District of Greater Chicago (MWRDGC) for review and

comment. Comments from MWRDGC were incorporated into the final version of the

questionnaire. The questionnaire was divided into the following two sections:
Section 3.0 - Data-Collection Activities

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C Section 1: General/Background Information; and

C Section 2: Information Regarding the Acceptance or Rejection of

Wastewater Containing Deicing Chemicals.

The questionnaire requested information regarding potential pollutants in

wastewater discharges to POTWs from airports, data to characterize the types of discharges the

POTW receives, and potential environmental impacts from accepting deicing wastewater

containing deicing agents. These data were used to assess the potential impacts that wastewater

discharges from airport deicing operations may have on POTW operations.

3.2.3.2 POTW Questionnaire Administration

The POTW questionnaire was mailed in August 1999 to nine selected POTWs. 

The Agency completed a detailed engineering review of the questionnaires and contacted by

telephone respondents who provided incomplete or contradictory technical information. The

information gathered from the questionnaires was summarized in a report and was used to provide

additional information on environmental impacts from the discharge of wastewater containing

deicing agents.

3.3 EPA Site Visits

The Agency conducted 16 engineering site visits at airports to collect information

about aircraft, runway, and taxiway deicing processes; deicing equipment; and deicing wastewater

generation, collection, handling, and treatment technologies. During these site visits, EPA also

evaluated potential sampling locations (as described in Section 3.4). One visit was conducted in

April 1997, prior to the formal commencement of this Study, and was used to gather preliminary

information about the industry. EPA site visits to the remaining airports examined a range of

deicing activities and management practices and took place from September 1997 through March

1999. 
Section 3.0 - Data-Collection Activities

3-8

EPA used information collected from literature searches and contact with trade

association members to identify representative airports for site visits. In general, the Agency

considered the following three criteria to select facilities that encompassed the range of

deicing/anti-icing operations, wastewater characteristics, and wastewater treatment practices: 

1. Size of airport;

2. Geographic location of airport (i.e., typical winter climate); and

3. Technologies in place (e.g., pollution prevention practices, collection

techniques, and on-site wastewater treatment facilities).

Airport-specific selection criteria are contained in site visit reports (SVRs) prepared for each

airport visited by EPA. Unfortunately, EPA was unable to visit all airports that represent the

broad range of size, location, and technologies and, therefore, used questionnaire data (see

Section 3.2.1) to augment EPA’s site visit program. 

During the site visits, EPA collected the following information: 

C General airport and deicing operations information, including size and age

of the airport, the party(ies) responsible for aircraft and pavement deicing,

and current airline tenants;

C A general description of deicing/anti-icing operations, including equipment

used, location(s) of deicing operations, chemicals used, and pollution

prevention techniques employed;

C Volumes, specific procedures, and type of fluid used for aircraft and

pavement deicing/anti-icing;

C Wastewater characterization information, including the typical volume of

ADF-contaminated storm water generated, collection methods used, and

pollutant concentrations;

C On-site wastewater treatment data, including the treatment technologies

used, treatment costs, monitoring, discharge, and permit information; and

C Airport financial information.
Section 3.0 - Data-Collection Activities

3-9

This information is documented in the SVR for each airport visited.

3.4 EPA Sampling

During the Study, the Agency conducted six sampling episodes. Two of these

were conducted to obtain data on ADFs. EPA conducted one episode to analyze Type I

undiluted ethylene glycol-based ADF and conducted another to analyze Type I undiluted

propylene glycol-based ADF. The four remaining episodes were conducted to obtain untreated

glycol-contaminated wastewater characterization data and treated final effluent data from airports

performing a variety of collection and treatment techniques. 

To obtain representative sampling data for the industry, EPA collected the

following samples:

C Storm water outfall which drains aircraft deicing/anti-icing areas (sample

collected during the deicing season, but not concurrent with a deicing

event);

C Wastewater discharge to a POTW from an airport retention basin used to

collect ADF-contaminated wastewater;

C Influent to and effluent from an anaerobic biological treatment system used

to treat ADF-contaminated wastewater at an airport;

C Influent to and effluent from a reverse osmosis treatment system used to

treat low-strength ADF-contaminated wastewater and to recover glycol for

further processing;

C Influent to and effluent from an aerobic biological treatment system used to

treat ADF-contaminated wastewater;

C Undiluted propylene glycol-based aircraft deicing fluid;

C Undiluted ethylene glycol-based aircraft deicing fluid;

C Trip blank(s);
Section 3.0 - Data-Collection Activities

3-10

C Equipment blank(s); and

C Duplicate wastewater samples. 

In general, the following classes of pollutants were analyzed:

C Whole effluent acute toxicity (WET)

– Pimephales Promelas (Fathead Minnow),

– Ceriodaphnia Dubia;

C Volatile organics (at only two sampling episodes);

C Semivolatile organics (including tolyltriazoles);

C Metals;

C Glycols;

C Biochemical oxygen demand, 5-day (BOD ); 5

C Total organic carbon (TOC);

C Hexane extractable material (HEM) and non-polar material (SGT-HEM);

and

C Ammonia as nitrogen.

The undiluted ADFs were diluted to 50% solutions with reagent grade water and analyzed for all

pollutant classes except BOD5, glycols, WET, HEM, and SGT-HEM. Section 8.3 discusses the

results of EPA’s sampling effort.

During the sampling period, field measurements of temperature, pH, nitrate/nitrite,

ammonia, and glycol concentration were collected for each sample point. Wastestream flow,

production data (i.e., number and type of aircraft deiced/anti-iced), and any information on

nondeicing/non-anti-icing operations that generate wastewater that is commingled with

deicing/anti-icing wastewater were also collected when available. 
Section 3.0 - Data-Collection Activities

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During the sampling episode, EPA and EPA contractor personnel collected and

preserved samples and shipped them to EPA contract laboratories for analysis. Sample collection

and preservation were performed according to EPA protocols as specified in the Quality

Assurance Project Plan for Field Sampling and Analysis at Airports (QAPP) (3) and the EAD

Sampling Guide (4).

In general, grab samples were collected from all sample streams. These streams

are not expected to significantly vary over time (i.e, samples were collected subsequent to

extended equalization). EPA collected the required types of quality control samples as specified

in the QAPP, such as trip blanks and duplicate samples, to verify the precision and accuracy of

sample analyses. The list of analytes for each episode, analytical methods used, and the analytical

results, including quality control samples, are included in the Sampling Episode Report (SER)

prepared for each sampling episode. 

3.5 Data Submitted by Airports

Facilities that discharge wastewater or storm water directly to surface waters of

the United States must have a National Pollutant Discharge Elimination System (NPDES) permit,

which can establish effluent limitations for various pollutants and require that facilities monitor the

levels of these pollutants in their effluent. POTWs may also require facilities to monitor pollutant

levels in their wastewater prior to discharge. EPA requested permit and self-monitoring data

from airports at which EPA conducted site visits as well as from those that responded to the

airport questionnaire. Self-monitoring data were submitted in various formats, including daily and

monthly summaries. The monitored pollutants varied among airports; however, most airports

monitor for BOD5 and/or glycols. These data were used to support EPA’s operations and

snowfall groupings and were used in combination with EPA’s sampling data to estimate pollutant

loadings discharged to U.S. surface waters (see Section 11.1). Table 3-1 at the end of this section

summarizes the specific types of data collected from individual airports.
Section 3.0 - Data-Collection Activities

3-12

3.6 Meetings with Federal Agencies, Industry Representatives, Trade

Associations, and Technology Vendors

Between 1997 and 1999, EPA participated in several meetings with the Federal

Aviation Administration (FAA), fluid formulators, airlines, industry associations, technology

vendors, and other interested parties to discuss environmental and operational issues related to

aircraft deicing and anti-icing operations. The purpose of the meetings was to gather current

detailed information about the industry. These meetings served as a forum for the transfer of

information between EPA and industry representatives on all aspects of airport deicing

operations, including wastewater collection and treatment technologies. EPA participated in

meetings with the following groups:

C Federal Aviation Administration;

C Airport, airline, and fixed based operator (FBO) representatives:

– American Association Airline Executives (AAAE),

– Airport Council International - North America (ACI-NA),

– Air Transport Association (ATA),

– Regional Airlines Association (RAA),

– Dames and Moore (a consultant to airlines and airports), and

– Air Canada; and

C Deicing/anti-icing fluid and treatment technology vendors:

– AR Plus and VQuip,

– Council for Environmentally Sound Deicing (CESD)/Lyondell

Chemical Company (formerly ARCO),

– EFX Systems,

– Inland Technologies, and
Section 3.0 - Data-Collection Activities

3-13

– Union Carbide.

In addition to meetings, EPA also attended the following industry conferences:

C The Seventh Annual Aircraft and Airfield Deicing Conference and 

Exposition held in Washington, DC in August 1998;

C Society of Automotive Engineers (SAE) G-12 Deicing Facilities

Subcommittee Meeting in Orlando, FL in October 1998;

C National Aviation Environmental Management Conference in Columbus,

OH in March 1999;

C Airport Deicing Summit (hosted by the Albany International Airport

Authority) in March 1999;

C The Clean Airport Summit held in Chicago, IL in April 1999;

C SAE G-12 Committee Meeting in Toronto, Canada in May 1999;

C The Eighth Annual Aircraft and Airfield Deicing Conference and

Exposition held in Washington, DC in August 1999; and

C SAE G-12 Deicing Facilities Subcommittee Meeting in Washington, DC in

November 1999.

By participating in these meetings and conferences, EPA was able to obtain up-todate information about aircraft and airfield deicing/anti-icing methods, wastewater collection and

treatment practices, and economic and financial aspects of the industry. EPA used this

information throughout its analyses and incorporated it into this report.

3.7 Literature

EPA performed several Internet and literature searches to identify papers,

presentations, and other applicable materials for use in the Study. Literature sources were

identified using the Dialog® service. Literature collected by EPA covers such topics as the
Section 3.0 - Data-Collection Activities

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toxicity of ADFs and their components, estimates of the volume of ADF used by the industry,

glycol mitigation techniques, alternative fluid types, pollution prevention practices, economic and

financial data, and environmental impacts. EPA also collected information from the U.S. Air

Force, which conducted its own study of deicing and anti-icing operations at Air Force bases.

EPA used data from these literature sources to estimate pollutant loadings to the

industry and to identify and describe deicing operations and practices, available treatment

technologies and their performance, toxicity data, environmental impacts, and trends in the

industry. 

3.8 Other Data Sources

In addition to the sources listed above, EPA collected data from the Permit

Compliance System and Toxics Release Inventory databases. These databases classify facilities

that discharge wastewater using four-digit Standard Industrial Classification (SIC) codes. EPA

used SIC code 4581 (Airports, Flying Fields, and Services) to identify facilities in the Permit

Compliance System and Toxics Release Inventory databases that potentially discharge aircraft

and/or pavement deicing/anti-icing wastewater. The Agency also used these databases to

calculate and/or validate pollutant loading estimates to the industry.

EPA also collected data from state, local, and other federal agencies. EPA spoke

with some state permitting agencies (e.g., NY, CT, WI) and local permit or pretreatment agencies

(e.g., Albany, Windsor Locks ) during site visits to gain a better understanding of local issues. 

EPA also collected data from the United States Geological Survey (USGS), which has been

performing a study at General Mitchell International Airport in Milwaukee, Wisconsin. The

USGS collected glycol samples from the airport’s outfalls and downstream of the receiving

waters. In addition, although EPA does not use a similar toxicity scale, the Agency acquired an

acute toxicity scale from the U.S. Fish and Wildlife Service that compares concentration to

toxicity. EPA Region 3 provided permit and sampling data for two airports in its jurisdiction,

Ronald Reagan Washington National Airport and Dulles International Airport. EPA also
Section 3.0 - Data-Collection Activities

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acquired, from FAA, operations and enplanement data for one full year, which were used in the

airport questionnaire development, and several advisory circulars, which were used to better

understand the industry and its current regulations. EPA also obtained extensive economic and

financial information from published reports by FAA, the Department of Transportation (DOT),

the Bureau of Transportation Statistics (part of DOT), and the General Accounting Office.

EPA also collected data from Environment Canada, the Canadian federal agency

responsible for environmental protection and conservation, and Transport Canada, the Canadian

federal agency responsible for transportation issues. Specifically, EPA collected information

about the Canadian Glycol Guidelines and the Canadian Water Quality Guidelines for Glycols

developed in the 1990s. Environment Canada and Transport Canada provided EPA with several

final, and in some cases draft, reports describing studies they have conducted to evaluate the

effect and fate of ADFs in the environment. These reports included results from several aquatic

toxicity studies performed using formulated ADFs. See Section 13.3 for more information

regarding the Canadian guidelines. 

3.9 References

1. Eastern Research Group, Inc. Development of Survey Weights for the U.S.

Environmental Protection Agency Aircraft and Pavement Screener Questionnaire

(DCN T10343). 

2. Eastern Research Group, Inc. Methodology for Selection of Mini-Questionnaire

Recipients. (DCN T10545).

3. Eastern Research Group, Inc. Quality Assurance Project Plan for Field Sampling

and Analysis at Airports. February 10, 1999 (DCN T10233).

4. Viar and Company. EAD Sampling Guide. June 1991 (DCN T10218).
Section 3.0 - Data-Collection Activities

3-16

Table 3-1

Summary of Data Submitted by Airports

Airport Information (a) Monitoring Data ADF Usage Volumes

Permit Analytical

Airborne Air Park U U

Albany International U U U

Anchorage International U U

Baltimore-Washington International U U U

Billings Logan International U U

Bradley International U U U

Buffalo International U U

Chicago O’Hare International U U U

Cleveland Hopkins International U U

Dallas-Ft. Worth International U U U

Denver International U U

Des Moines International U U

Duluth International U U

General Mitchell International U U U

Greater Rockford U U U

Kansas City International U U U

Key Field (Meridian) U U

Logan International U U U

Minneapolis-St. Paul International U U

Newark International U U

Portland International U

Richmond International N/A

Ronald Reagan Washington National U U U

Seattle-Tacoma International U U

Salt Lake City International U U

Tri-State (Huntington) U U

Washington Dulles International U U U

N/A - Not applicable (i.e., no current storm water permit in place).

(a) Although general permit information were available, specific permit information (e.g., monitored parameters and

frequency) was not always provided.
Section 4.0 - Technical Profile

Note that civil landing areas do not include stand-alone military landing areas (i.e., military landing areas that are not 1

located at a public airport).

4-1

4.0 TECHNICAL PROFILE

This section presents an overview of the air transportation industry (Section 4.1), a

description of airport deicing/anti-icing operations (Section 4.2), and a profile of the airport

deicing operations “industry” (i.e., airports that have deicing/anti-icing operations) (Section 4.3). 

Information presented in this section is based on data provided by facilities in response to screener

questionnaires, mini-questionnaires, EPA site visits and sampling episodes, and data collected

from other non-EPA sources (see Section 3.0).

4.1 Air Transportation Industry Overview

EPA is mainly concerned with deicing/anti-icing activities at facilities classified

within Standard Industrial Classification (SIC) code 4581 (Airports, Flying Fields, and Airport

Terminal Services). There are different types and sizes of airports, as well as aircraft serving

these airports, depending on the airport and its location. For example, some airports that serve

only cargo carriers generally service only large jets. The Federal Aviation Administration (FAA)

has created several different classification codes for airports and aircraft. These classifications are

mainly used for FAA funding purposes. 

4.1.1 Airport Types and Sizes

There are currently 18,345 civil landing areas in the U.S., which include airports 1

as well as landing areas developed specifically for helicopters and seaplanes (1). Although the

FAA is responsible for controlling all airspace, it does not control all airports. The FAA has

identified 3,344 airports that are currently important to national transportation (1). Most of these

airports are owned by the cities or counties they serve and only a few airports are privately

owned. Of the approximately 15,000 civil landing areas that are not considered important to
Section 4.0 - Technical Profile

4-2

national transportation, 1,000 do not meet the minimum criteria to be considered important; 1,000

are located at inadequate sites, are redundant to publicly owned airports, or have too little activity

to qualify for inclusion; and the remaining 13,000 are not open to the general public (1). 

Airport size can be measured either by enplanements or operations. The FAA

defines airport size based on enplanements. Commercial service airports are those that are

publicly owned, receive passenger service, and have 2,500 or more annual enplanements. Primary

commercial airports are those with more than 10,000 annual enplanements; nonprimary

commercial service airports are those with annual enplanements ranging from 2,500 to 10,000. 

According to the FAA, in January 1998 there were 413 primary commercial airports and 125

nonprimary commercial service airports (1). The FAA further classifies primary commercial

airports by hubs. Large hub airports are defined as those airports with 1% or more of all U.S.

enplanements, medium hubs are those with 0.25% to 0.9999% of enplanements, small hubs are

those with 0.05% to 0.2499% of enplanements, and nonhubs are those with 10,001 to 0.0499%

of enplanements. In addition to commercial service, there are classifications for general aviation

(GA) and reliever airports. Most civil aircraft operations occur at GA airports, which comprise

95% of all airports and service 98% of all registered civil aircraft. Reliever airports are typically

general aviation airports that are located near a commercial service airport and serve as a reliever

to congested airports. The number of airports in each category is listed below.

Category Number of Airports Percentage of U.S. Enplanements

Commercial Primary Large hub 29 67%

Medium hub 42 22%

Small hub 70 7%

Nonhub 272 3%

Non- Other 125 <1%

primary

Relievers 334 0%

General aviation 2,472 0%

Source: Reference (1).
Section 4.0 - Technical Profile

4-3

The FAA also maintains records of airport operations (number of arrivals and

departures) for FAA-towered or contractor-towered airports. EPA is not aware of any FAA

airport size categories defined by airport operations. Operations are divided into the following

aviation categories that are described below: air carrier, air taxi, general aviation, and military

operations. 

Aviation Category Definition

Air carrier A certified aircraft with a seating capacity of more than 60 seats or a

maximum payload capacity of more than 18,000 pounds carrying

passengers or cargo for hire or compensation; includes U.S. and foreign

flag carriers. The four types of air carriers are: majors, nationals, large

regionals, and medium regionals.

Air taxi An aircraft designed to have a maximum seating capacity of 60 seats or

less or a maximum payload capacity of 18,000 pounds or less carrying

passengers or cargo for hire or compensation; may also be referred to as

a commuter aircraft if noncertified.

General aviation Takeoffs and landings of all civil aircraft, except those classified as air

carriers or air taxis.

Military All classes of military operations (e.g., Air Force, Army, Navy, U.S.

Coast Guard, Air National Guard) at FAA air traffic facilities.

Source: Reference (2).

Section 14.1 provides a detailed profile of significant economic and financial

aspects of U.S. airports.

4.1.2 Geographic Location of Airports

Airports are distributed throughout the entire U.S., and more likely to be located

near population centers. According to the FAA, 70% of the U.S. population resides within 20

miles of at least one of the 538 commercial airports (1). A large percentage of primary hub

commercial airports (97% in 1996) are located adjacent to environmentally sensitive areas (i.e.,

water bodies) such as wetlands, rivers, coastal areas, creeks, and lakes (3). 
Section 4.0 - Technical Profile

4-4

4.1.3 Types of Airlines

Airlines are classified by the services they offer and their annual revenues. The

four classifications for airlines are: major, national, regional, and cargo. They all operate under

federal regulations; however, the regulations to which a particular airline is subject depends on

their aircraft fleet. Section 14.2 provides a detailed profile of significant economic and financial

aspects of U.S. airlines.

Major airlines earn annual revenues of $1 billion or more in scheduled service. 

There were 12 major airlines in the U.S. in 1996 (4). These carriers generally can provide

scheduled service with large aircraft (i.e., aircraft with 61 or more seats and a payload of more

than 18,000 pounds) (4). 

National airlines earn annual revenues of between $100 million and $1 billion in

scheduled service (4). Many of the airlines in this category serve particular regions of the

country, although this is not required. These carriers mostly operate medium and large size jets

(4).

Regional carriers are airlines whose services are generally limited to a single region

of the country. These carriers are divided into three groups: large, medium, and small. Large

regional carriers earn annual revenues of between $20 million and $100 million and operate

aircraft with more than 60 seats. Medium regional carriers earn annual revenues of less than $20

million, but operate aircraft similar to large regional carriers. Small regional carriers, often called

commuters, are the largest segment of the regional airline business and mostly operate planes that

have less than 30 seats. There is no revenue cut-off for this group (4).

Regional airlines may be private business carriers, commercial airlines, charter

airlines, or airlines that provide a combination of these services. Private business carriers

represent about 60% of the flights of regional airlines. Regional airlines serve all airports served

by the major airlines as well as 300 smaller airports that are not served by any major airline. At
Section 4.0 - Technical Profile

4-5

larger airports, all of the regional airlines typically operate out of one gate area. However, some

regional airlines that are affiliated with major airlines (e.g., American Eagle, which is affiliated

with American Airlines) may have their own gate areas or use the same gate areas as their larger

affiliate. Although regional airlines carry about 10% of all airline passengers, they represent about

40% of all flight operations. Regional airlines conduct a disproportionately large number of flight

operations per passenger because their aircraft are smaller, and, therefore, carry fewer passengers

per operation. In addition, their aircraft have a higher utilization rate, shorter flights, and spend

less time on the ground between flights.

Cargo carriers are airlines that primarily carry cargo using aircraft called

“freighters” (4). Freighters are essentially passenger aircraft with all or nearly all of the passenger

seats removed. There is no revenue cut-off for this group.

4.2 Deicing/Anti-Icing Operations

A major concern for the safety of passengers is the clearing of ice and snow buildup on runways, taxiways, roadways, gate areas, and aircraft. Two basic types of deicing/antiicing operations are generally performed at an airport: the deicing/anti-icing of aircraft, and the

deicing/anti-icing of paved areas, including runways, taxiways, roadways, and gate areas. The

most common technique for the deicing/anti-icing of aircraft is the application of chemical

deicing/anti-icing agents. Deicing of runways, taxiways, and roadways is most commonly

performed using mechanical means but may also be performed using chemical agents. The antiicing of paved areas is typically conducted with anti-icing chemicals. The following subsections

describe the methods and materials used to deice and anti-ice aircraft and paved areas at airports.

4.2.1 Aircraft Deicing/Anti-icing

Aircraft deicing involves the removal of frost, snow, or ice from an aircraft. 

Aircraft anti-icing generally refers to the prevention of the accumulation of frost, snow, or ice. 

Both are typically discussed as one operation throughout this section.
Section 4.0 - Technical Profile

4-6

The responsibility for performing deicing/anti-icing varies between airports, but it

is usually performed by a combination of individual airlines and fixed-based operators (FBOs). 

Airlines typically select procedures for deicing/anti-icing their aircraft, which are then approved by

the FAA. EPA is aware of only one airport authority, Westchester, New York, that performs

aircraft deicing. Even in this case, the airport authority functions as an FBO when performing

deicing operations. 

In the deicing/anti-icing process, aircraft are usually sprayed with deicing/anti-icing

fluids (ADF) that contain chemical deicing agents; however, nonchemical methods are also

performed. Deicing/anti-icing occurs when the weather conditions are such that ice or snow

accumulates on an aircraft. During snowstorms, freezing rain, or cold weather that causes frost to

accumulate on aircraft surfaces including the wings, deicing is necessary to ensure the safe

operation of aircraft. Studies have concluded that even very little icing, if located on critical

aircraft surfaces (e.g., leading edge of the wing), can cause significant decreases in lift. Typical

tests show that 1/32nd of an inch of ice accumulation along the leading edge of a large jet or

1/64th of an inch on a smaller aircraft can decrease lift on takeoff from 12% to 24%, depending

on the size of the aircraft (5). 

The typical deicing season runs from October through April. In colder areas the

deicing season may extend over a longer period, and in warmer climates the deicing season may

be shorter, with the exception of frost removal, which may rarely be done.

ADF works by adhering to aircraft surfaces to remove and/or prevent snow and ice

accumulation. Nonchemical methods use mechanical or thermal forces to prevent, remove, or

melt ice and snow. Two types of deicing are performed: wet-weather and dry-weather deicing,

depending on a number of climatic and operational factors. Wet-weather deicing is performed

during storm events that include precipitation such as snow, sleet, or freezing rain. Dry-weather

deicing is performed when changes in the ambient temperature cause frost or ice to form on

aircraft but no precipitation is present. Dry-weather deicing may also be performed on some

types of aircraft whose fuel tanks become super-cooled during high-altitude flight, resulting in ice
Section 4.0 - Technical Profile

4-7

formation at lower altitudes and after landing. Dry-weather deicing may occur at temperatures up

to 55E Fahrenheit (F), but generally requires a significantly smaller volume of deicing fluid than

wet-weather deicing.

During typical wet-weather conditions, 150 to 1,000 gallons of ADF may be used

on a single commercial jet, while a much smaller volume, as little as 10 gallons, may be used on a

small corporate jet (6, 7, 8). An estimated 1,000 to 4,000 gallons may be needed to deice a

commercial jet during severe weather conditions (9). Aircraft anti-icing fluids are applied in much

smaller volumes than their deicing counterparts. A commercial jet requires approximately 35

gallons of fluid for anti-icing after deicing (7). Generally, dry-weather deicing requires 20 to 50

gallons of deicing fluid, depending on the size of the aircraft (7, 10). 

4.2.1.1 Fluid Types

Aircraft deicers are categorized into four classes: Type I, Type II, Type III, and

Type IV. Not all types are currently used. Fluid types vary by composition and allowed holdover

times (i.e., the amount of time the residual fluid will protect an aircraft from ice formation). Type

I is the most commonly used fluid and is used primarily for aircraft deicing. These types of fluids,

which contain either ethylene glycol or propylene glycol, water, and additives, remove

accumulated ice and snow from aircraft surfaces. Types II, III, and IV were developed for antiicing and form a protective anti-icing film on aircraft surfaces to prevent the accumulation of ice

and snow. Anti-icing fluids are composed of either ethylene glycol or propylene glycol, a small

amount of thickener, water, and additives. The additives in aircraft deicing and anti-icing fluids

may include corrosion inhibitors, flame retardants, wetting agents, identifying dyes, and foam

suppressors. 

Type II and Type IV fluids were designed for use on all types of aircraft while

Type III fluids were designed for use on smaller, commuter aircraft. Most of the larger U.S.

airlines use Type IV fluids exclusively for aircraft anti-icing because of its increased holdover

time, but many smaller and regional airlines use Type II fluids due to cost considerations (Type IV
Section 4.0 - Technical Profile

4-8

fluids require specialized application equipment). According to a representative from the

Regional Airlines Association (RAA), Type III fluids are not currently used, and are not available

for purchase. 

FAA regulations do not stipulate which fluid should be used but recommend that

commercial carriers and owners of private aircraft use fluids that meet the standards set by the

Society of Automotive Engineers (SAE) (see Section 13.5). All current formulations in the U.S.

use either ethylene glycol or propylene glycol as a freezing point depressant. Diethylene glycol is

also an approved freezing point depressant; however, no diethylene glycol-based deicing fluids are

currently used in the U.S. 

Temperature and weather conditions dictate the required concentration of glycol in

any type of fluid. Some entities that perform deicing vary the glycol concentration based on

weather conditions (concentrations may range from 30% to 70% glycol). This is referred to as

“blending to temperature.” Others use the same concentration regardless of weather conditions. 

Those who use the same concentration throughout a deicing season typically use a concentration

applicable to worst-case cold weather conditions (usually around 50% glycol). This conservative

practice may result in fewer operator mistakes and is particularly suited to smaller airports that

lack storage for preparing multistrength solutions. 

Type I fluids are commonly purchased as concentrated glycol solutions (8% water,

90% glycol, and <2% additives) and diluted as needed prior to application. Type II and IV fluids

are sold preformulated to the appropriate concentration (33% water, 65% glycol, and 2%

additives) and do not require dilution prior to application. 

4.2.1.2 Fluid Uses

All ADFs work by lowering the freezing point of water. ADF is applied to ensure

that the freezing point of any water on aircraft remains at a temperature not greater than 20E F

below the ambient air or aircraft surface temperature, whichever is lower (FAA Advisory Circular
Section 4.0 - Technical Profile

4-9

No. 20-117). All ADFs must lower the freezing point of water to -18E F or lower when applied. 

A typical Type I deicing fluid contains approximately 50% to 60% glycol after being diluted for

application. This concentration will depress the freezing point of water to between -40E F and -

50E F. Current formulations of propylene glycol-based ADFs require a greater concentration of

glycol than ethylene glycol-based ADFs to attain the same freezing point depression. The

minimum freeze point for ethylene glycol-based ADFs (approximately -58E F) occurs when the

fluid consists of approximately 60% ethylene glycol and 40% water. The minimum freeze point

for propylene glycol-based ADFs (-75E F) is lower than that for ethylene glycol-based ADFs, but

occurs at a higher glycol concentration. 

The main difference in capability among all of the different fluid types is the

holdover time. Holdover time is the period of time when ice or snow is prevented from adhering

to the surface of an aircraft (i.e., the amount of time between application and takeoff). Type I

fluids have between a 6- and 15-minute holdover time in a light snow. Because of this brief time

span, Type I fluids are used for deicing and for only short-term anti-icing protection. Although

rarely used, Type II fluids provide approximately a 45-minute holdover time in a light snow. 

Type IV fluids can provide up to a 70-minute holdover time, depending on atmospheric

conditions. Because anti-icing fluids are more expensive than deicing fluids, larger amounts of

Type I fluids are commonly used to remove snow and ice and then much smaller amounts of antiicing fluid are applied if necessary. 

Most larger airlines use both Type I and Type IV fluids, while smaller commercial

airlines may use both Type I and Type II fluids or no anti-icing fluids at all. Smaller airlines have

been generally unable to afford the specialized equipment required to apply Type IV fluids, 

although some small airlines may be deiced by FBOs that use Type IV fluids. Also, some small

airlines have recently purchased used Type IV application trucks from larger airlines who have

upgraded to trucks that can apply both Type I and Type IV fluids. Airlines that can afford to

invest in specialized equipment first evaluate if Type IV fluids are necessary at each of their

stations by analyzing historical weather data, airline operations figures, airport infrastructure, and
Section 4.0 - Technical Profile

4-10

airport congestion. For example, increased holdover times provided by Type IV fluids may not be

necessary at small airports with short taxiing times and no congestion. 

Although Type IV fluids are more effective at preventing ice formation than Type I

fluids, they are not as effective at depressing the freezing point of water. Therefore, airports

located in colder regions may use Type I fluids for both deicing and anti-icing.

4.2.1.3 Fluid Application

Deicing fluids are generally heated to 150E F to 180E F prior to application, while

anti-icing fluids are typically applied at ambient temperatures. All fluid types are usually applied

under pressure using a nozzle. The pressure of the liquid hitting the surface of the aircraft

physically removes some of the snow and ice, while the high temperature and chemical properties

of the fluid melts the remaining snow and ice. The solution that remains on the aircraft helps

prevent further snow and ice build-up. Special nozzles are necessary to apply anti-icing fluids due

to their high viscosity. When ambient temperatures are above 26E F, the FAA allows the use of

hot water (heated to 140E F) to melt and remove snow and ice followed by application of antiicing fluid. Most airlines do not currently use this method because it is considered to be too

dangerous and could compromise passenger safety. A major concern with hot water deicing is

flash freezing (i.e., freezing on contact with aircraft) and the potential to build thick layers of ice

both on the aircraft and on the ground.

ADF is generally stored in either above-ground storage tanks, underground

storage tanks, tank trucks, or mini-bulk (450-gallon) containers. Type I fluids are either diluted in

mixing vessels, or mixed as they are pumped into deicing trucks or tank trucks using a

proportioner. This device pumps both concentrated deicing fluid and water simultaneously at

predetermined flow rates to achieve a desired solution concentration. If the fluid requires heating

prior to application, it is heated in mixing vessels or in trucks. 
Section 4.0 - Technical Profile

4-11

ADF is typically applied using deicing trucks or fixed booms. Some deicer trucks

contain multiple storage compartments to carry deicing fluids of varying strengths or types. 

Storage tanks may be equipped with thermal blankets to heat the fluids. Deicing trucks typically

have a movable boom with a cherry picker equipped with a nozzle at the end of the boom. An

operator in the cherry picker basket directs the high-pressure spray at aircraft surfaces, while a

driver moves the truck. Specially designed deicing trucks may be used to deice areas of the

aircraft that are low to the ground or hard to reach, such as landing gear.

Some airports are equipped with fixed-boom deicing equipment, which typically

includes a permanently mounted boom with a nozzle, or a cherry picker with a nozzle, that moves

along the boom. Pumps supply ADF from mixing tanks to the boom. Because fixed booms are

less mobile than deicing trucks, deicing trucks may be needed to deice hard-to-reach areas not

serviced by the booms. 

Prior to application, many operators test their ADF to determine its glycol

concentration. Densitometers and refractometers are two types of equipment often used to

measure glycol concentrations in the field. After deicing operations are complete, some fluid may

remain in deicing trucks and mixing vessels. This fluid is typically stored in the trucks or pumped

into a storage tank until the next deicing event. The fluid (including Type I fluid diluted to

application strength) may be stored at the end of the deicing season for use the following season. 

Aircraft deicing and anti-icing operations usually occur at terminal gates, gate

aprons, taxiways, or pads. Aircraft deicing/anti-icing pads may be located near terminals and

gates, along taxiways serving departure runways, or near the departure end of runways. Each

airport may use only one or a combination of all of these locations for deicing/anti-icing. The

amount and type of deicing performed at each location may vary. For example, an airport with

aircraft deicing/anti-icing pads may allow only minimal deicing (i.e., engines and wheel base) at

gates, the minimum amount of deicing necessary to move the aircraft safely, and require all other

deicing to be conducted at the pad. 
Section 4.0 - Technical Profile

4-12

If deicing is not conducted at the gate, then, prior to takeoff, an aircraft will taxi to

airport-approved deicing/anti-icing locations. Depending on the deicing location design, several

aircraft may be deiced simultaneously on a single deicing pad. Deicing trucks and/or fixed booms

apply the appropriate ADF. From one to four deicer trucks may be used for deicing a single

aircraft, depending on its size and weather conditions. Estimates based on EPA site visits to

airports indicate that deicing application time may range from 5 to 20 minutes, while anti-icing

application time ranges from 4 to 6 minutes. When holdover times are exceeded prior to takeoff,

secondary deicing/anti-icing is necessary. Secondary deicing/anti-icing is typically conducted at a

remote deicing/anti-icing pad adjacent to the runway, if available. However, many airports are

not equipped with remote deicing/anti-icing pads, and aircraft must return to the gate or other

designated deicing/anti-icing locations for secondary deicing/anti-icing, which can substantially

delay their departure. The need for secondary deicing will likely decrease as more airlines use

Type IV fluids to extend the allowable holdover time.

4.2.1.4 Variables That Affect Fluid Use

The variables that affect the volume of deicing fluid used and the time needed to

deice aircraft include: ambient temperature; amount of snow and ice build-up on aircraft; aircraft

type and size; type/severity of current precipitation; deicing fluid glycol concentration; aircraft

surface temperature; relative humidity; solar radiation; wind velocity and direction; deicing

procedure used; proximity to other aircraft, equipment, and buildings; aircraft component

geometry and surface roughness; and the deicing personnel. Climatic- and weather-related

influences are the predominant variables that affect fluid usage and are described in Section 5.0. 

The FAA has issued regulations on when and how to conduct deicing/anti-icing

operations to ensure safe air travel. They have also published advisories and guidance for

designing aircraft deicing facilities and for conducting aircraft deicing/anti-icing under various

weather conditions and aircraft types. However, the aircraft pilot is ultimately responsible for

determining whether the deicing performed is adequate. The pilot may inspect the aircraft after

deicing and order additional deicing or anti-icing. 
Section 4.0 - Technical Profile

4-13

EPA learned from data-collection efforts that one of the most significant

operational factors affecting fluid usage is personnel. A large portion of aircraft deicing staff,

particularly at larger airports, is newly hired and trained each year. High employee turnover

results from low pay and poor work conditions (e.g., exposure to storm events and fluid). In

addition, airlines at hub airports tend to use temporary employees for aircraft deicing. Although

the cost of fluid can prevent wasting fluid, many of these new hires are initially taught that “a little

is good, but more is better,” and spray more fluid than is necessary due to the potential liability

associated with improperly deicing an aircraft. Although new hires receive eight hours of FAAmandated training, industry sources tell EPA that three years of experience is required to become

adept at aircraft deicing. Personnel turnover is generally much lower at smaller airports because

aircraft deicing staff at these airports tend to have other responsibilities, such as baggage handling

or maintenance. See Section 6.2.16 for additional information on personnel training and recent

industry efforts to improve this factor.

4.2.1.5 Dry-Weather Deicing

Dry-weather deicing, also referred to as clear ice deicing, may be performed

whenever ambient temperatures are cold enough to form ice on aircraft wings (below 55E F). 

Dry-weather deicing is also used to defrost windshields and wingtips on commuter planes and is

usually conducted throughout the entire deicing/anti-icing season.

Airplane models MD-80s and DC-9s are more likely to require dry-weather

deicing than other aircraft because their fuel tanks are located under their wings. The tanks may

become super-cooled during flight, causing frost or ice to form on the wings when the aircraft

lands. Generally, only a small volume of aircraft deicing fluid is needed to remove this ice,

approximately 20 to 50 gallons per aircraft. Some airlines are attempting to eliminate the need for

dry-weather deicing by retrofitting these aircraft with specially designed thermal blankets;

however, these blankets have caused corrosion problems in electric systems.
Section 4.0 - Technical Profile

4-14

4.2.1.6 Nonchemical Deicing Methods

Nonchemical deicing methods use mechanical or thermal means to remove ice and

snow from aircraft. Dry, powdery snow can be swept from aircraft using brooms or brushes. Hot

air blowers can also be used to remove snow mechanically with forced air and also to melt ice and

snow. In addition, some smaller aircraft are equipped with inflatable pneumatic or hydraulic boots

that can expand to break ice off of the leading edges of wings and elevators.

Mechanical snow removal methods (e.g., using nylon brooms and ropes to remove

snow from parked aircraft) are typically only used in the early morning because they are time- and

labor-intensive and would be too disruptive to airline schedules during the day. Mechanical

methods are typically also used in conjunction with fluid application and are dependent on climate

and operational variables. Personnel must be properly trained and provided with appropriate

equipment so as not to damage navigational equipment mounted on aircraft. Airlines typically use

brooms to remove as much snow and ice as possible before applying conventional aircraft deicing

fluids. 

Forced-air/hot-air deicing systems are currently in operation at a few U.S. airports

and are being assessed by several airlines (see Section 6.2.3 for more detailed information). These

systems use forced air to blow snow and ice from aircraft surfaces. Some systems allow deicing

fluids to be added to the forced air stream at different flow settings (e.g., 9 and 20 gpm), while

other systems require separate application of deicing fluid. Several vendors are currently

developing self-contained, truck-mounted versions of these forced-air systems, and most systems

can be retrofitted onto existing deicing trucks. 

A similar method to truck-mounted forced-air systems is the double gantry forcedair spray system. The gantries support a set of high- and low-pressure nozzles, which blast the

aircraft surfaces with heated air at 40 to 500 pounds per square inch. When weather conditions

are severe, a small volume of water and glycol may be added to the air stream to remove dense
Section 4.0 - Technical Profile

4-15

coverings of snow and ice. Use of the gantry system is limited because it is a permanently

mounted system and has been known to cause bottlenecks and delay aircraft departure. 

Another alternative to chemical deicing/anti-icing methods is infrared (IR) heating

of aircraft. One IR system consists of an open-ended hangar-type structure with natural gas

powered IR generators suspended from the ceiling. The IR wavelengths are targeted to heat ice

and snow, and minimize heating of aircraft components. The IR energy and wavelength may be

adjusted to suit the type of aircraft. Although the system can deice an aircraft, it cannot provide

aircraft with anti-icing protection. Consequently, when the ambient temperature is below

freezing, anti-icing fluid is typically applied to the aircraft after it leaves the hangar. Testing is

being planned to determine if it is possible that melted snow and ice can refreeze prior to Type IV

application following IR deicing. Since the aircraft surfaces are dry, the volume of anti-icing fluid

required is less than for typical anti-icing operations. In addition, a small amount of deicing fluid

may be required for deicing areas of the aircraft not reached by the IR radiation, such as the flap

tracks and elevators. The system, therefore, does not completely replace glycol-based fluids, but

greatly reduces the volume required. See Section 6.2.5 for additional information on IR deicing.

4.2.2 Pavement Deicing/Anti-icing

Pavement deicing/anti-icing removes or prevents the accumulation of frost, snow,

or ice on runways, taxiways, aprons, gates, and ramps. A combination of mechanical methods

and chemical deicing/anti-icing agents are used for pavement deicing at airports. Runway

deicing/anti-icing is typically performed by the airport’s operating authority or a contractor hired

by the authority. Some ramp, apron, gate, and taxiway deicing/anti-icing may be performed by

other entities, such as airlines and FBOs that operate on those areas. Pavement deicing typically

occurs during the same season as aircraft deicing, but may be shorter than the aircraft deicing

season.
Section 4.0 - Technical Profile

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4.2.2.1 Mechanical Methods

Mechanical methods, such as plows, brushes, blowers, and shovels for snow

removal, are the most common form of runway deicing, and may be used in combination with

chemical methods. Airports generally own multiple pieces of snow removal equipment and have

employees trained to operate them. Because winter storm events can be unpredictable, personnel

trained in pavement deicing/anti-icing may be available at an airport 24 hours a day during the

winter season. 

4.2.2.2 Chemical Methods

Because ice, sleet, and snow may be difficult to remove by mechanical methods

alone, most airports use a combination of mechanical methods and chemical deicing agents. 

Common pavement deicing and anti-icing agents include ethylene glycol, propylene glycol, urea,

an ethylene glycol-based fluid known as UCAR (containing approximately 50% ethylene glycol,

25% urea, and 25% water by weight), potassium acetate, sodium acetate, sodium formate, and

calcium magnesium acetate (CMA). Sand may be used to increase the friction of icy paved areas,

but it may be detrimental to the mechanical workings of aircraft. Salt (i.e., sodium chloride or

potassium chloride) may be used to deice/anti-ice paved areas that are not used by aircraft (e.g.,

automobile roadways and parking areas) but are not considered suitable for deicing/anti-icing

taxiways, runways, aprons, and ramps because of their corrosive effects. Potassium acetate has

also been reported as potentially degrading insulation in electrical systems (e.g., runway lights). 

An industry workgroup is currently investigating this issue.

Many airports perform deicing of heavy accumulations of snow and ice using

mechanical equipment followed by chemical applications. Pavement anti-icing may be performed

based on predicted weather conditions and pavement temperature. Deicing and anti-icing

solutions are applied using either truck-mounted spray equipment or manual methods. Section

6.5 further discusses pavement deicing/anti-icing operations.
Section 4.0 - Technical Profile

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4.3 Airports with Deicing/Anti-Icing Operations

The number of airports performing deicing/anti-icing operations in the U.S. is

unknown. In addition, the amount of deicing/anti-icing fluids or agents used varies greatly among

airports, as does the amount of wastewater generated. Factors affecting the amount of

deicing/anti-icing fluids used and the volume of wastewater generated include airport size, airport

location and weather, and airlines using the airport. These and other industry characteristics are

described in the following subsections. 

4.3.1 Number of Airports Performing Aircraft and Runway Deicing

EPA is not aware of any sources estimating the number of airports performing

aircraft and pavement deicing operations. EPA also recognizes that not all airports that perform

deicing/anti-icing operations contribute significant pollutant loadings to the environment from

these activities. For example, a large airport in Florida may deice aircraft only approximately 10

days per year for defrosting purposes. These operations are not likely to significantly impact the

surrounding environment (or publicly owned treatment works (POTW)) because only a small

amount, if any, of spent deicing fluid enters the environment, and pollutant loadings from these

airports would be negligible. Therefore, for purposes of this study, EPA focused on airports that

potentially perform significant deicing/anti-icing operations. 

4.3.1.1 Number of Airports Potentially Performing Significant Deicing/Anti-Icing

Operations

EPA determined potentially significant deicing/anti-icing operations based on

airport size and weather. In general, deicing/anti-icing operations include aircraft deicing, which

is typically performed by airlines or a FBO, and pavement deicing, which is typically performed by

airports. EPA received aircraft operations and total enplanement data from the FAA for over 400

airports, and used aircraft operations data as a measure of airport size for the following reasons. 

First, aircraft deicing is performed on a per-aircraft basis, which is more closely related to airport
Section 4.0 - Technical Profile

4-18

operations than enplanements. Second, the volume of aircraft deicing fluid (ADF) required for

deicing is not impacted by whether or not the aircraft is fully loaded with passengers. For the

purposes of this study, EPA selected a benchmark of 10,000 operations per year (excluding

general aviation) to represent significant operations; therefore, the Agency excluded airports with

less than 10,000 annual operations from further analyses. EPA did not include general aviation in

its operation measurement because EPA believes that most general aviation aircraft do not

operate during deicing conditions. 

EPA also used weather information to identify airports that are likely to perform

potentially significant deicing/anti-icing operations. For the purposes of this study, EPA

determined that mean annual snowfall (including ice pellets and sleet) of less than 1 inch would

not result in significant deicing operations; therefore, EPA excluded airports in regions with

annual snowfall less than 1 inch from further analyses. 

As a result, EPA focused on wastewater generated and the impact associated with

deicing events at airports with annual operations greater than 10,000 (excluding general aviation)

and an average of 1 inch or greater of snowfall per year. Figure 4-1, located at the end of this

section, shows a geographic representation of the estimated 212 airports that meet these criteria. 

As expected, these airports are highly concentrated in the eastern part of the U.S. where the

population is more dense. Few airports are located in the far South, where there is little or no

snowfall. EPA is aware that other airports (e.g., private, military, or non-FAA-towered) may

exist that meet the criteria defined above; however, EPA was limited by the data provided by the

FAA. 

4.3.1.2 Other Estimates of Number of Airports

In a survey of the top 125 busiest airports in the U.S. (including territories)

conducted by the National Resources Defense Council (NRDC) in 1996, 61 airports supplied data

concerning deicing activities at the airport. Out of the 61 airports that responded, 51 answered

that they perform deicing, eight answered that they do not perform deicing, and two answered
Section 4.0 - Technical Profile

4-19

that they only rarely deice (6). The eight airports that do not deice are located outside the

continental U.S. (e.g., Puerto Rico, Virgin Islands), or are located in very warm climates (e.g.,

Fort Lauderdale, FL, Phoenix, AZ). Both Los Angeles International and San Francisco

International responded that they did not deice in the timeframe for which data were requested,

which suggests that there are several airports along the coast of California which may perform no

deicing. Overall, the majority of large airports do deice (6). 

Air Transport Association members have indicated that the deicing industry

primarily comprises 40 airports and 25 airlines, while American Association of Airport Executives

(AAAE) members have stated that approximately 90% of deicing operations are performed at

10% of airports (11). AAAE distributed a questionnaire in 1993 to 340 airports to collect

information about deicer usage and aircraft operations. Of the 59 airports that responded to the

questionnaire, approximately one-half reported using glycol-based ADFs (11). 

EPA did not use the results of the NRDC study to estimate the total number of

airports that perform deicing operations because the survey was limited only to the 125 busiest

airports, which does not cover all airports that EPA believes perform significant deicing

operations. Similarly, EPA did not rely on ATA and AAAE members’ assessments of the number

of airports performing significant deicing/anti-icing operations because they are not based on

statistically valid surveys. 

4.3.2 Annual ADF and Pavement Deicer Usage

The volumes of aircraft and pavement deicing/anti-icing fluids or agents used has

varied greatly over the past decade. EPA has identified several sources that estimate the amount

of aircraft and/or pavement deicer usage. EPA did not consider any one source as correct or

absolute. The data presented in this section are informative only and are not necessarily directly

comparable. In general, the data show that deicer usage has increased, probably due to the

combination of the following factors: 1) deicer usage is highly dependent on weather conditions,

which can vary greatly from year to year; 2) deicer users report volumes in different fluid
Section 4.0 - Technical Profile

4-20

concentrations, which are sometimes incorrectly compared to one another; 3) an airline crash in

1992 heightened awareness of the potential danger associated with ice, which resulted in

increased fluid usages for the next several years; and 4) increased usage of anti-icing (i.e., Type II

and IV) fluids may have decreased the volume of deicing (i.e., Type I) fluids required. 

1992 FAA Survey

In 1992, the FAA conducted a survey of airport deicing/anti-icing operations at

U.S. airports to address operational practices and storm water controls at that time. Results of

the survey were used to assist airports in complying with the EPA’s recently promulgated storm

water program (see Section 12.1). Ninety-six airports, representing a wide range of airport sizes

and locations, responded to the questionnaire. However, several major airports did not submit a

questionnaire and several respondents did not fully answer all questions. Therefore, the data

collected from the survey should be considered anecdotal information and not a statistical

representation of the industry at that time.

According to the FAA survey, the predominate aircraft ADF used at that time was

ethylene glycol; only 24 airports reported using any propylene glycol. Only four airports in the

survey reported using anti-icing fluids (Type II) (12). 

According to the FAA survey, most airports used urea and/or ethylene glycol for

pavement deicing. For airports that reported using ethylene glycol for pavement deicing/antiicing, volumes ranged from 200 gallons to 187,000 gallons per airport. Twenty-nine airports

combined reported using over a total of 800,000 gallons of ethylene glycol as a pavement deicer

between 1989 and 1991. For airports that reported the use of urea as a pavement deicer, volumes

ranged from 100 pounds to 715 tons per airport. Twenty-seven airports reported a combined

total use of over 4,000 tons of urea as a pavement deicer between 1989 and 1991. One airport

reported using calcium magnesium acetate (CMA) and another reported using potassium acetate. 

Several airports noted using UCAR, a pre-mixed solution of ethylene glycol, urea, and water. 

Propylene glycol was allowed as a runway deicer subsequent to the FAA survey (12).
Section 4.0 - Technical Profile

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According to the FAA survey, the average annual volume of ethylene glycol used

for aircraft deicing by all respondents between 1989 and 1991 was approximately 2.16 million

gallons. Individual airports reported ethylene glycol use for aircraft deicing ranging from 0.6 to

520,000 gallons per year. As expected, the largest volumes were generally associated with the

FAA large hubs. For the same time period, only 650,000 gallons of propylene glycol were used

with individual airports reporting propylene glycol use ranging from 75 gallons to 250,000 gallons

per year. Only a few airports reported using Type II fluids, from 300 to 10,000 gallons per year

(12).

1993 AAAE Survey

According the AAAE survey discussed above, most deicer usage reported

involved glycol-based ADFs. ADF usage for the 59 airports that responded to the survey ranged

from 0 to 1,200,000 gallons per year (Note: AAAE’s report did not specify the basis year for

glycol usage data). The median glycol usage was 3,650 gallons per year, and the mean was

44,600 gallons per year. AAAE found that seven airports (12% of the respondents) used more

than 50,000 gallons of glycol per year; these respondents accounted for 85% of the total glycol

used by all respondents. AAAE also found that 44 airports (75% of the respondents) used less

than 20,000 gallons of glycol per year; these respondents accounted for only 6% of the total

glycol used by all respondents (11).

Other Non-EPA Estimates

Researchers estimate that at least 11 million gallons of concentrated ADF were

used at the 20 largest airports in North America during the winter of 1992-1993 (8). 

Environment Canada has estimated that an average of 14 million gallons of concentrated ADF are

used in North America in a typical year (13). 
Section 4.0 - Technical Profile

4-22

1992 EPA Screener Questionnaire

Based on an analysis of results from EPA’s screener questionnaire (see Section

3.1), the Agency estimates that 5.3 million gallons of ADF were used in 1992. Note that the

screener questionnaire did not specify whether the reported volume is as concentrated or applied

volumes; therefore, these data likely represent multiple dilutions. ADF volumes ranged from 1

gallon per year to 672,393 gallons per year per facility (note that multiple “facilities” (i.e., airlines

and FBOs) may operate at a given airport). Ethylene glycol, urea, and sand were the most

common pavement deicing agents in 1992. The estimated total volume of liquid pavement deicers

used in 1992 was 12,300 gallons, with volumes ranging from 10 to 5,500 gallons per facility. The

estimated total volume of solid pavement deicers used in 1992 was 950,000 pounds, with

amounts ranging from 20 to 234,544 pounds per facility. Other pavement deicers reported as

being used in 1992 include propylene glycol, potassium acetate, CMA, and sodium formate (14).

Post-1993 EPA Deicing Study Data-Collection Activities

EPA used data collected from site visits and mini-questionnaires to estimate ADF

usage. The following table summarizes the range of ADF volumes used by fluid type for these

airports. Note that there are wide ranges due to differences in climate and severity of weather

conditions in the years for which data were requested. 

Fluid Type Range of Volumes Used Per Airport (Gallons/Year)

Type I ethylene glycol-based 3,500 - 700,000(a)

Type II/IV ethylene glycol-based 600 - 180,000

Type I propylene glycol-based 257 - 833,000(a)

Type II/IV propylene glycol-based 2,500 - 143,000

Source: Reference (14).

(a) These volumes are expressed as “concentrated” volumes (i.e., they do not account for water addition).

In general, most U.S. airports reported that both ethylene glycol- and propylene

glycol-based fluids are used at their airport; however, several airports reported that only
Section 4.0 - Technical Profile

4-23

propylene glycol-based fluids are used. The range of applied ADF volumes (after accounting for

dilution of Type I fluids) per airport is 514 to 2,134,000 gallons per year (15). 

EPA estimates a current annual national ADF applied usage volume of 35 million

gallons at 212 facilities based on information collected from EPA’s 1999 mini-questionnaires (see

Section 3.2) and site visits conducted between 1997 and 1999 (see Section 3.3) and the

extrapolation methodology described in Section 11.0. Note that as discussed in Section 11.0, not

all ADF applied is discharged.

According to EPA site visits and the mini-questionnaire, the most common

pavement deicer is potassium acetate, although several facilities still use urea. Most airports also

use sand to help increase friction between aircraft and pavement surfaces. Several airports noted

that they recently discontinued the use of urea and/or ethylene glycol due to environmental

concerns, such as high biochemical oxygen demand (BOD).

4.4 References

1. Federal Aviation Administration. Report to Congress: National Plan of Integrated

Airport Systems (NPIAS) 1998 - 2002. Washington, D.C., 1999 (DCN T11096).

2. Federal Aviation Administration. FAA Statistical Handbook of Aviation. Chapter

2, National Airspace System. Washington, D.C., 1997.

3. Federal Aviation Administration. Report to House Committee on Transportation

and Infrastructure and Senate Committee on Commerce, Science, and

Transportation: Airports Located Adjacent to Environmentally Sensitive Areas. 

Washington, D.C., March 1996 (DCN T10349, Attachment F).

4. Air Transport Association. Airline Handbook. www.air-transport.org.

5. Valentine, Barry. What’s the Problem We’re Trying to Solve. The Airport

Deicing Advisor, November 1999 (DCN T11071).

6. Natural Resources Defense Council. Flying Off Course. 1996 (DCN T10267).
Section 4.0 - Technical Profile

4-24

7. U.S. Environmental Protection Agency. Site Visit Report. Buffalo Niagra

International Airport (DCN T10352).

8. Mericas, D. and B. Wagoner. “Managing Deicing Fluid’s Impact on Airport

Stormwater.” Water Environment and Technology. December 1994 (DCN

T09971).

9. Noble, Denise. “Controlling Glycol in Runoff.” Environmental Technology,

Sept/Oct 1997 (DCN T04677).

10. U.S. Environmental Protection Agency. Site Visit Report. Dallas/Ft. Worth

International Airport (DCN T10364).

11. Stormwater Permitting of Airports, Comments from Mr. David Jeffrey, AAAE to

Mr. William Swietlik, U.S. EPA. February 17, 1994 (DCN T10532).

12. Federal Aviation Administration. FAA Survey Final Report Stormwater

Questionnaire Project. Washington, D.C., June 1, 1992 (DCN T00215).

13. Cancilla, D. et al. Detection of Aircraft De-icing/Anti-icing Fluid Additives in a

Perched Monitoring Well at an International Airport. 1998 (DCN T10466).

14. Memorandum from A. Baynham, ERG to S. Zuskin, U.S. EPA. Summary

Statistics for Responses to Aircraft and Pavement Deicing/Anti-icing Questions

Contained in the U.S. Environmental Protection Agency Aircraft and Pavement

Screener Questionnaire. July 30, 1998 (DCN T10346).

15. U.S. Environmental Protection Agency. Summary Matrix of Airport

Questionnaires and EPA Site Visits. 1999. (DCN T11073).
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Section 4.0 - Technical Profile

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Figure 4-1

Geographic Distribution of Airports with Annual Operations Greater than 10,000 and

Mean Annual Snowfall Greater than 1 Inch
Section 5.0 - Climactic Influences and Deicing/Anti-Icing

Agent-Contaminated Wastewater Generation and Discharge

5-1

5.0 CLIMATIC INFLUENCES AND DEICING/ANTI-ICING AGENTCONTAMINATED STORM WATER GENERATION AND DISCHARGE

This section discusses the impact that climatic factors such as temperature,

precipitation, and humidity (i.e., atmospheric moisture) have on deicing/anti-icing agent usage,

which subsequently impacts the amount of contaminated storm water generated and pollutant

concentrations discharged. Section 5.1 discusses various types of climatic conditions that result in

the need for airport deicing operations. Section 5.2 discusses methods to measure these

conditions, and examines each method as a possible indicator of the amount of deicing/anti-icing

agents used. Section 5.3 describes EPA’s estimate of the total deicing/anti-icing agentcontaminated storm water volume generated, and Section 5.4 discusses discharge of contaminated

storm water. Appendix A contains information regarding the location of airports referenced in

this section.

5.1 How Climatic Conditions Affect Deicing/Anti-icing Chemical Usage

 Most airport deicing/anti-icing operations typically occur due to low temperatures

and/or precipitation. Without these environmental factors, significant airport deicing/anti-icing

operations would probably not exist. Airports generally use significant volumes of deicing/antiicing agents because of some form of precipitation (i.e., storm event). While it is true that several

airports use deicing/anti-icing agents when there is no precipitation, the volumes of agents used

under these conditions are typically very small compared to the volumes used during storm

events. In most cases, deicing/anti-icing agents used during nonstorm (i.e., dry-weather deicing)

events are retained on or evaporate from the pavement, and do not enter an airport’s storm water

collection system. Because fluid used during dry-weather deicing is relatively small compared to

that during storm events and does not generally generate contaminated storm water, EPA believes

the vast majority of contaminated storm water is generated during precipitation events.

Precipitation includes snowfall, rainfall, sleet (including freezing rain), and ice. 

Each of these conditions affect the volume and type of deicing/anti-icing agents required to
Section 5.0 - Climactic Influences and Deicing/Anti-Icing

Agent-Contaminated Wastewater Generation and Discharge

5-2

adequately prevent ice from forming on aircraft and pavement surfaces. Although there are no

specific guidelines for the volume of deicing/anti-icing agents required based on precipitation

type, deicing/anti-icing agents are generally used in greatest quantities when the ambient

temperature is near or below freezing and there is heavy (or wet) accumulating snow or ice falling

or forming on surfaces. In contrast, relatively small volumes of deicing/anti-icing agents are

required for dry, powdery snow conditions, which can be removed easily using mostly mechanical

methods.

Rain at or near freezing temperatures may also require significant deicing/anti-icing

agent usage as a precaution because a slight temperature decrease would result in significant ice

or snow formation. Unlike snow, ice strongly adheres to aircraft and pavement surfaces, making

it more difficult to remove. Freezing rain is said to require the most deicing/anti-icing agent usage

because the rain freezes on contact with the aircraft or pavement surface and coats to form a

solid layer of ice.

5.2 Correlating Climatic Conditions to Deicing/Anti-icing Agent Usage

When considering the impact of climatic conditions on deicing operations, EPA

evaluated the following four different climatic measures: 1) mean annual snowfall, 2) snowfall

duration, 3) mean annual days below freezing, and 4) heating degree days. Each of these

measures is described in more detail below, including the advantages and disadvantages of

correlating each measure to deicing/anti-icing agent usage.

5.2.1 Mean Annual Snowfall

Mean annual snowfall can be measured in terms of depth of snow or liquid

equivalence of snowfall. Depth of snow is a measure of the snow height relative to a ground

point that is considered zero depth; it is commonly measured by the National Oceanic and

Atmospheric Administration (NOAA) in inches. Liquid equivalence measures snow density and

can be used to compare snowfall density in two different regions. Liquid equivalence converts
Section 5.0 - Climactic Influences and Deicing/Anti-Icing

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5-3

the depth of snowfall in a given region to a liquid volume. For example, if Denver received 12

inches of snow and New York received 4 inches of snow, the amount of snowfall, in terms of

liquid equivalence, may be the same if the snowfall in New York were significantly “wetter.” 

Mean annual snowfall is a good measure of the intensity of precipitation over a

deicing season; however, it does not differentiate between an area with 10 5-inch storms and an

area with two 25-inch storms. Although both areas have a total of 50 inches of snow per year,

the deicing/anti-icing chemical usage at airports in these areas would differ greatly (assuming all

other operational factors are equivalent).

EPA believes that mean annual snowfall, in terms of snowfall depth, is the best

measure to use when correlating deicing/anti-icing agent usage to weather because these data are

readily available for most airports and measure the total amount of precipitation received over a

deicing season. Appendix B contains mean annual snowfall data for select U.S. cities and

Appendix C contains a contour map of the U.S. in terms of snowfall depth. EPA is aware that

there are several other site-specific factors, such as the type of precipitation (e.g., freezing rain

versus dry snow), number of operations, aircraft size, and applicator training, that dictate the

amount of deicing fluid used. 

5.2.2 Snowfall Duration

Duration of snowfall is another potential measure of deicing/anti-icing agent usage. 

This measure records the time duration of snowfall and may indicate the amount of time for which

deicing/anti-icing agents are applied; however, it does not measure snowfall intensity. Atlases

typically include snowfall durations.
Section 5.0 - Climactic Influences and Deicing/Anti-Icing

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5-4

5.2.3 Mean Annual Days Below Freezing

Another potential measure of deicing/anti-icing agent usage is the mean number of

days in a year during which the temperature falls below 32E F. While this measure is a good

indicator of how cold the ambient temperature is and the potential for deicing, it does not actually

measure precipitation. Therefore, an airport may be in a very cold location with a high number of

days below 32E F, but may be in a dry climate and experience very little precipitation. This

airport would probably use less deicing/anti-icing agents compared to another airport in a warmer

location (on average) with more snow or ice. 

5.2.4 Heating Degree Days

The final measure considered by EPA is number of heating degree days per year

(an engineering index of heating fuel requirements), calculated by finding a daily mean

temperature (calculated from the maximum and minimum temperatures recorded for the day), and

subtracting it from 65E F. For example, if the mean temperature for a given day is 40E F, then

there are 25 heating degree days associated with that calendar day. If the daily mean temperature

is 65E F or greater, then there are zero heating degree days. These data are kept by the National

Weather Service, a division of NOAA. However, heating degree days are a measure of

temperature, not precipitation, and therefore, may not correlate to deicing/anti-icing agent usage. 

According to a NOAA representative, the colder the temperature, the less precipitation is likely to

occur, such as in Northern Canada, which receives little snowfall even though it is extremely cold

(1). Thus, deicing/anti-icing agent usage would be less in very cold, dry areas than in cold, moist

areas.

5.3 Volume of Contaminated Storm Water Generated

EPA is not aware of any estimates of the annual volume of storm water

contaminated with deicing chemicals that is generated by airports. In fact, the amount of storm

water generated by deicing/anti-icing operations can be highly variable from year to year and is
Section 5.0 - Climactic Influences and Deicing/Anti-Icing

Agent-Contaminated Wastewater Generation and Discharge

5-5

difficult to quantify because it is very site- and storm-specific. The volume of storm water

generated from deicing operations is a function of precipitation, deicing/anti-icing agent usage,

and airport wastewater containment and collection techniques. Even during particular

precipitation events, many airports do not know how much deicing/anti-icing agent-contaminated

storm water is generated because they are not able to contain all of it. For these airports,

contaminated storm water either runs off to grassy areas where it is retained or percolates into the

ground. EPA is aware that, to make a more accurate conclusion regarding total storm water

generation, more site-specific information including the size and runoff coefficient(s) of the

drainage areas and storm water drainage and control structures would be required.

EPA also recognizes that site-specific airport deicing/anti-icing procedures will

affect the volume of contaminated wastewater generated. If an airport performs deicing/anti-icing

operations only in designated areas, lesser volumes of contaminated wastewater will be generated

than at an airport that does not limit deicing/anti-icing operations to a designated area (all other

factors being equal). Specifically, the unconstrained airport would generate a greater volume of

contaminated wastewater with lower pollutant concentrations. Therefore, EPA recognizes that

each airport generates a unique volume of contaminated wastewater.

Other storm water discharges associated with industrial activities at airports

include discharges from aircraft fueling, cleaning, and maintenance areas, car rental services, and

washing areas. The volume of storm water generated from these other sources is site-specific and

may not be commingled with deicing/anti-icing contaminated storm water. For the purposes of

this study, EPA did not specifically consider storm water other than that from aircraft and airfield

pavement deicing areas. 

EPA obtained estimates of collected contaminated wastewater volumes from

airports that the Agency visited. Albany International Airport collects between 15 and 25 million

gallons of contaminated wastewater per year. Bradley International Airport collected 350,000

gallons of contaminated wastewater in January 1999. Minneapolis-St. Paul International Airport

collects approximately 9 million gallons of contaminated wastewater per year. 
Section 5.0 - Climactic Influences and Deicing/Anti-Icing

Agent-Contaminated Wastewater Generation and Discharge

5-6

While EPA recognizes that the volume of contaminated wastewater is unique to

each airport and deicing season, estimating a general range of volume of deicing/anti-icing agentcontaminated wastewater generated in the U.S. is important to evaluating past, present, and

future pollutant concentrations discharged from deicing/anti-icing operations. For the purposes of

this study, EPA estimated the volume of contaminated wastewater using the estimated aircraft

deicing/anti-icing fluid (ADF) usage volume (provided in Section 11.1) and the range of glycol

concentrations (i.e., ethylene glycol and propylene glycol) in contaminated storm water. Using

sampling data provided by the industry and from EPA’s data-collection efforts, EPA determined

that a nondetect glycol concentration is a reasonable lower bound of expected glycol

concentrations. Because airports use different analytical methods with different analytical

detection limits, EPA used a common detection limit of 10 mg/L. For the upper bound, EPA

used the highest detected glycol concentration from the sampling data, 47,000 mg/L (2). Using

this range of glycol concentrations and EPA’s estimate of the total annual volume of ADF applied

(based on EPA’s estimate of the 212 airports with potentially significant deicing operations), EPA

estimates that the annual volume of ADF-contaminated storm water generated in any specific year

ranges between 300 million and 1.4 trillion gallons per year. Based on a visual inspection of the

arrayed sampling data, EPA believes that an average of approximately 7 billion gallons of

contaminated storm water is generated per year. (See Section 11.1 for a discussion of pollutant

loadings discharged to surface waters.) 

5.4 Method of Contaminated Storm Water Discharge

Based on EPA’s data-collection activities for this study, airports discharge storm

water contaminated with deicing agents either directly to surface waters or both directly to

surface waters and indirectly to a POTW. Specifically, EPA identified 11 airports that hold both

direct and indirect discharge permits versus 13 airports that hold only direct discharge permits (3). 

In addition, one airport did not hold a discharge permit (the airport uses evaporation), and one

airport holds only an indirect discharge permit. Section 13.2 describes permit conditions.
Section 5.0 - Climactic Influences and Deicing/Anti-Icing

Agent-Contaminated Wastewater Generation and Discharge

5-7

The choice of utilizing direct, indirect, or a combination of wastewater discharge

results largely from airport infrastructure; the choice of best management practices employed at

the airport; the stringency of the state NPDES permit; and whether the POTW will accept

wastewater from airport deicing operations. Although the discharge of wastewater generated

from deicing/anti-icing activities is typically the responsibility of the airport where these activities

take place, there are often several other entities involved (e.g., airlines, fixed-based operators

(FBOs)). In some cases, airlines and/or FBOs are co-permittees on airport discharge permits. 

For example, Des Moines International Airport has an NPDES permit with co-permittees. The

City of Des Moines is the owner and operator of the airport and acts as the airport’s

representative and coordinates co-permittee efforts to achieve permit compliance. The copermittees are tenants of the airport facility, including airline companies, FBOs, military or other

government establishments, and other parties that have contracts with the airport authority to

conduct business operations on airport property that result in storm water discharges associated

with industrial activities (including deicing areas). 

5.5 References

1. Personal communication between Melissa Cantor, ERG, and Roy Rasmussen,

National Center for Atmospheric Research. August, 1999. (DCN T10694).

2. Stormwater Monitoring Results (1990-1999). Bradley International Airport (DCN

T10522).

3. U.S. Environmental Protection Agency. Summary Matrix of Airport

Questionnaires and EPA Site Visits. 1999. (DCN T11073).
Section 6.0 - Pollution Prevention

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6.0 POLLUTION PREVENTION

EPA’s storm water program combined with local environmental issues such as fish

kills and odor problems have prompted airports and airlines to investigate a wide range of

pollution prevention practices designed to eliminate or minimize the environmental impact of

aircraft deicing/anti-icing fluids (ADFs) and airfield pavement deicing/anti-icing chemicals without

compromising safety. This section summarizes the pollution prevention practices used by U.S.

airports, military bases, and foreign commercial airports, and provides information about pollution

prevention methods and technologies currently under development. Practice- or technologyspecific costs are provided where available. Additional cost information provided by technology

vendors and airports is included in Section 11.2

To date, there are four basic approaches to pollution prevention for aircraft

deicing/anti-icing operations: (1) elimination of glycol-based fluids through the development of an

environmentally benign alternative fluid; (2) minimization of the volume of fluid applied to aircraft

through the development of better fluids, improved application methods, and innovative aircraft

deicing technologies; (3) development of collection and disposal strategies that prevent the release

of ADF-contaminated wastewater to the environment; and (4) development of glycol recycling

methods. Approaches to pollution prevention for airfield pavement deicing/anti-icing operations

include: (1) adoption of alternative pavement deicing/anti-icing chemicals that are less harmful to

the environment; (2) reduction or elimination of pavement deicing/anti-icing chemicals through

the implementation of alternative deicing/anti-icing technologies; and (3) minimization of the

amount of agents applied through the use of good maintenance practices, preventive anti-icing

techniques, and runway condition monitoring systems. Although each approach is discussed

separately, a combination of pollution prevention practices are typically used at U.S. airports. 

The pollution prevention practices selected by an airport or airline for use at a particular airport

often depend on a variety of airport-specific factors, including climate; total amount of chemical

deicing and anti-icing agents applied; number of airlines; aircraft fleet mix; number of aircraft

operations; costs; presence of existing infrastructure; availability of land; and impact on aircraft
Section 6.0 - Pollution Prevention

6-2

departures. EPA recognizes that some of the pollution prevention practices discussed in this

section may not be practical or economically feasible for all U.S. airports. 

Section 6.1 discusses alternative aircraft deicing/anti-icing agents, and section 6.2

describes aircraft deicing fluid minimization methods. Section 6.3 presents aircraft deicer/anti-icer

collection and containment methods. Section 6.4 discusses glycol recycling and Section 6.5

presents pollution prevention practices for airfield parent deicing/anti-icing operations. Appendix

A contains information regarding the location of airports referenced in this section.

6.1 Alternative Aircraft Deicing/Anti-Icing Agents

One plausible solution to the environmental problems associated with glycol-based

ADFs is their replacement with more environmentally benign products. Despite considerable

interest in developing substitute ADFs, little progress has been made. Most of the current

research is thought to be in a preliminary stage and it will likely be some time before a suitable

replacement is found. Substitute products need to be biodegradable and less toxic than current

products, but must also contain compounds that are noncorrosive to aircraft parts. To be

economically viable, substitute chemicals must be inexpensive and at least as effective in

maintaining air safety as the glycol-based fluids they replace.

The National Aeronautics and Space Administration’s Ames Laboratory in

California is attempting to develop effective, non-glycol-based aircraft deicing and anti-icing

agents (1). The current status of the project is unknown, but the research is believed to be

progressing slowly. 

The U.S. Air Force has also expressed interest in finding an environmentally

benign substitute for glycol-based ADFs (2). The Air Force Office of Scientific Research is

currently funding a number of research projects designed to discover a nontoxic, biodegradable

ADF. Many of these projects focus on discovering how naturally occurring antifreeze molecules

inhibit ice crystal growth. For example, Professor John Duman at the University of Notre Dame
Section 6.0 - Pollution Prevention

6-3

is exploring the structure of antifreeze molecules found in overwintering larvae of the beetle

Dendroides canadensis to determine how these molecules inhibit ice crystal growth. A similar

project directed by Professor Chi-Hing Cheng-DeVries of the University of Illinois is investigating

antifreeze molecules found in polar fish. The goal of these projects is to synthesize a naturally

occurring compound that can be formulated into an effective, nontoxic, anti-icing agent. 

6.2 Aircraft Deicing Fluid Minimization Methods

Since it is unlikely that any new products will be available in the near future, the

U.S. Air Force and some domestic carriers have been investigating ways to reduce the volume of

ADF used, without compromising safety. The ADF minimization methods described in this

section enable pollution to be reduced through source reduction.

6.2.1 Type IV Anti-icing Fluids

Aircraft anti-icing fluids are designed to adhere to aircraft surfaces and prevent ice

and snow build-up for set periods of time, known as holdover times. Currently, two types of

aircraft anti-icing fluids are used in the United States, Type II and Type IV fluids. Although Type

I fluids can provide limited anti-icing protection, they are primarily used for deicing aircraft, are

generally applied in much larger volumes, and typically provide less than 15 minutes holdover

time. Type II and Type IV fluids are similar to Type I fluids, but contain thickening agents,

usually polymers, that provide improved anti-icing properties. The viscosity of anti-icer fluids

decreases with wind shear, which enables the fluids to be shed from aircraft surfaces during

takeoff. Type IV fluids represent the most recent advances in aircraft anti-icing agents and

provide longer holdover times than Type II fluids. Although holdover times vary with weather

conditions, the typical holdover time for a Type II fluid is approximately 45 minutes in a light

snow. Type IV fluids, however, may provide protection for as long as 70 minutes under the same

weather conditions (3). Due to their improved anti-icing capabilities, Type IV fluids have been

credited with reducing the amount of deicing fluid used by eliminating repeated deicing and anti-
Section 6.0 - Pollution Prevention

6-4

icing of aircraft prior to takeoff (4). Most of the larger U.S. carriers now use Type IV fluids

exclusively for anti-icing. 

One potential disadvantage of using Type IV fluids is the possibility for increased

airfield contamination. Because Type IV fluids adhere to aircraft surfaces, greater use of Type IV

fluids may increase the volume of fluid deposited on runways and adjacent grassy areas. Since

runways rarely have contaminated storm water collection systems, anti-icing fluids shed from

aircraft during takeoff enter the environment and may contaminate soils, groundwater, and nearby

streams. Although some components of anti-icing fluids, such as glycols, are easily degraded by

microorganisms present in soils, other components, such as tolyltriazoles, are believed to persist

in the environment (see Section 10.1.2).

6.2.2 Preventive Anti-icing

Preventive anti-icing is the application of glycol-based anti-icing fluid prior to the

start of icing conditions or a storm event to limit ice and snow build-up and facilitate its removal. 

The principal advantage of this method is an overall reduction in the volume of glycol-based fluids

applied to aircraft. Anti-icing fluids are applied in much smaller volumes than their deicing Type I

counterparts. A Boeing 727, for example, can be anti-iced using approximately 35 gallons of

fluid, whereas deicing requires at least 150 gallons of Type I fluid and may be as much as 2,000

gallons during a severe storm event. To be effective as a preventative, anti-icing fluids must be

applied to aircraft prior to the advent of icing conditions or a storm event.

The U.S. Air Force has also experimented with preventive anti-icing techniques

and has concluded they can be effective in reducing the volume of fluid applied to aircraft,

provided operations personnel carefully coordinate their activities with local weather reports (2). 

The U.S. Air Force has not implemented widespread use of preventive anti-icing practices due to

concerns that anti-icing fluids may degrade aircraft parts, particularly those made from composite

materials, when the fluids are left on for extended periods (5).
Section 6.0 - Pollution Prevention

6-5

One drawback to preventive anti-icing is the problem of obtaining accurate

weather forecasts containing enough information for operations personnel to make informed

decisions. Inaccurate forecasts may result in unnecessary anti-icing. Operations personnel

typically rely on local weather stations to provide accurate and timely weather forecasts; however, 

several U.S. airlines have established meteorological groups, which provide weather forecasts for

major destinations. The National Center for Atmospheric Research in Boulder, Colorado, has

developed a new weather forecasting system specifically designed for use at airports that provides

snowfall forecasts thirty minutes in advance of precipitation. The system is known as Weather

Support to Deicing Decision Making (WSDDM) and its development was funded by the Federal

Aviation Administration (FAA) (6). Forecasts are based on information collected from surface

weather stations, snow-weighing gauges, and Doppler radars located at or near the airport. The

information is processed by computers and displayed graphically on video monitors at the airport. 

During the 1997-1998 winter season, the system was tested by Delta and U.S. Airways at La

Guardia airport in New York and by United and American at O’Hare airport in Chicago. In July

1998, the WSDDM system became available commercially from ARINC, a company specializing

in aviation communication and air traffic management systems. The system costs approximately

$100,000 to install. It is currently in operation at La Guardia airport, where it is used by Delta for

managing aircraft deicing/anti-icing and by the New York Port Authority for managing airfield

snow removal. Airlines hope this system will provide sufficient storm warning information to

perform preventive anti-icing of aircraft prior to the arrival of a storm, enabling airlines to

continue to operate safely with less deicing fluid.

Anti-icing fluids are sometimes applied to aircraft to provide overnight protection

from frost and storm events. This practice is purported to greatly reduce the volume of Type I

fluid needed to remove ice and snow from aircraft surfaces the following morning. For example,

a fixed-base operator at one airport reported applying Type IV fluid for overnight protection to

one of two aircraft parked side by side. A major snow storm occurred during the night and both

aircraft were deiced the next morning using Type I fluid. The aircraft treated with Type IV fluid

required 860 gallons of Type I fluid to deice, while the untreated aircraft required 1,820 gallons
Section 6.0 - Pollution Prevention

6-6

(7). Several airlines, however, have expressed concern that anti-icing fluids may dry out and

damage aircraft if left on for extended periods (8).

Several U.S. airlines (United, Delta, American, and Midwest Express) have

experimented with anti-icing aircraft immediately after landing (1). The intent is to prevent ice

and snow build-up while the aircraft is at the gate, and consequently reduce the amount of deicing

and anti-icing required before departure. For aircraft with short turn-around times, the protection

afforded by preventive anti-icing may even eliminate the need for further deicing prior to

departure. Study results indicate this practice saves time and reduces the amount of Type I fluid

used during a storm event (1). 

6.2.3 Forced-Air Aircraft Deicing Systems

Forced-air aircraft deicing systems have been available for many years, but have

not seen widespread application in the United States primarily due to their high cost over

conventional deicing systems. The first systems used a high-pressure air jet to blast ice and snow

from aircraft surfaces, which has proven to be very effective for removing dry, powdery snow

from cold, dry aircraft surfaces. All Nippon Airways, for example, has used forced-air systems

for over 20 years to remove overnight accumulations of snow at several northern airports in Japan

and believe it removes dry snow faster than using deicing fluids. All Nippon Airways personnel

can reportedly remove 5 cm of snow from a passenger jet in about 15 minutes using a forced-air

deicing system. 

In the past, U.S. carriers were less enthusiastic about forced-air systems because

they were not very effective for removing ice and wet snow; conditions that are typical for most

U.S. airports. In recent years, however, the development of new hybrid systems, which combine

forced-air with fine sprays of heated Type I fluids, have rekindled interest in this technology. 

In the early 1990s, FMC Corporation (formerly Aviation Environmental

Compliance Inc.) developed a forced-air aircraft deicing system designed to remove snow and ice
Section 6.0 - Pollution Prevention

6-7

from aircraft surfaces using a high-pressure air stream combined with a fine spray of glycol-based

aircraft deicing fluid. The system is known as the AirFirst Deicing SystemTM and can be used in

an air-only mode for removing light snow and ice. The system consists of a self-contained, truckmounted unit fitted with a turbine engine and a dual source nozzle. The dual source nozzle allows

deicing fluid to be added to the air stream to help remove ice and protect against freezing

precipitation (2, 5). 

 Today, forced-air aircraft deicing systems are also manufactured by Premier,

Global, and Vestergaard and are similar to the FMC AirFirst Deicing SystemTM. The Premier

system, known as the Hybrid Deicing SystemTM (HDS), was developed in collaboration with

Allied Signal and consists of a centrifugal compressor, an ADF storage tank with heater, a highpressure fluid pump, and a coaxial nozzle. The coaxial nozzle is designed to emit a high-velocity

stream of heated ADF surrounded by a high-velocity air jet. The compressed air exits the nozzle

at approximately 750 miles per hour. ADF can be applied at either 9 gpm (7,500 psi) or 20 gpm

(3,300 psi), depending on the weather conditions. The unit can also be operated in an air-only

mode for removing dry snow. HDS units are currently used by Delta Airlines at General Mitchell

International Airport in Milwaukee, Wisconsin, and by the U.S. Navy at the Brunswick Naval Air

Station in Maine. For the 1998-1999 deicing season, Delta estimates the HDS unit enabled the

airline to reduce the volume of ADF used in Milwaukee by about 85% (9, 10). 

The Vestergaard system is mounted on Vestergaard’s Elephant Gamma Deicer

truck and uses forced air combined with an ADF spray to deice aircraft. The unit supplies forced

air at a pressure of 56 psi and can be operated with or without ADF injection. The first

Vestergaard forced-air system was purchased by All Nippon Airways last year and is currently

used at the Nagano Airport in Japan to remove snow from aircraft parked at the airport overnight. 

The Global system, known as AirPlusTM, is a self-contained unit weighing

approximately 85 pounds that consists of a compressor and two articulated nozzles (one for ADF

and the other for forced air). Unlike the other forced-air systems where the compressor is

mounted on the truck, the compressor on the Global system is mounted under the operator’s seat
Section 6.0 - Pollution Prevention

6-8

in the enclosed cab attached to the articulated boom. AirPlusTM can be operated in four different

modes: (1) forced air only; (2) forced air with ADF injection; (3) ADF and forced air (supplied by

separate nozzles); and (4) ADF only. The forced air exits the forced air nozzle at 725 miles per

hour (about 1,350 cfm) with a pressure of 11 psi. ADF can be injected into the air stream at

approximately 10 gallons per minute. The second nozzle can provide either heated Type I fluid at

60 gallons per minute or Type IV fluid at 20 gallons per minute. The cargo carrier, Emery

Worldwide, tested the unit at Dayton International Airport in Ohio during the 1998-1999 deicing

season. For the 1999-2000 deicing season, five AirPlusTM systems will be used by American

Airlines at Chicago O’Hare International Airport and two will be used by Skyway Airlines (a

division of Midwest Express) at General Mitchell International Airport in Milwaukee. According

to Global representatives, the AirPlusTM system can reduce the volume of ADF used by an airline

by at least 30 percent. 

The forced-air systems cost approximately $250,000. FMC and Global also

market retrofit kits for use on existing deicing trucks that cost between $80,000 and $100,000

(2). To date, only a limited number of hybrid forced-air deicing systems have been purchased by

U.S. carriers (e.g., Delta, United, American, Northwest, Emery Worldwide, Skyway, and Federal

Express). Airlines have been cautious about investing in this new technology for a variety of

reasons, the most important being concern the high-velocity air jet will damage aircraft surfaces. 

When a forced-air system is used to remove ice, airlines are concerned that ice chunks blasted

from aircraft surfaces at high velocity will injure ramp personnel or damage aircraft. Many

airlines are also worried the forced-air systems will be more expensive to maintain and less reliable

than traditional deicer trucks. Some airlines believe that widespread use of forced-air systems will

result in higher purchase prices for ADF due to reduced demand. Despite these problems, forcedair deicing systems offer several benefits to the airline industry, including reductions in the volume

of fluid purchased, less frequent refilling of deicer trucks, and reduced costs for wastewater

disposal. 

The principle environmental benefit of the hybrid forced-air deicing systems is their

ability to minimize the volume of fluid required to deice aircraft; however, glycol-based anti-icing
Section 6.0 - Pollution Prevention

6-9

fluids may still need to be applied in certain weather conditions. While conventional deicing with

large volumes of hot Type I fluids provide temporary anti-icing protection by heating the aircraft

surface, forced-air deicing systems provide little anti-icing protection. Consequently, the time

between completion of deicing and application of anti-icing fluids may be less than with

conventional deicer trucks. 

The U.S. Air Force has also experimented with forced-air deicing and has

developed a system that uses forced hot air to remove snow and ice from aircraft surfaces. The

forced hot air is supplied by MA1A compressors, which have been fitted to existing deicer trucks. 

The forced hot air system does not eliminate glycol-based ADFs, which are typically applied to

aircraft after treatment with forced hot air. Nevertheless, it greatly reduces the volume of fluid

required to effectively deice aircraft. The forced hot air system is currently in use at several

northern Air Force bases (5, 11, 12, 13). 

6.2.4 Computer-Controlled Fixed-Gantry Aircraft Deicing Systems

An alternative approach to aircraft deicing are the fixed-gantry systems, which are

self-contained “car wash style” aircraft deicing systems. Fixed-gantry systems have been installed

at only a few airports worldwide, and, although purported to deice aircraft quickly and efficiently,

they have failed to receive widespread approval from the industry. EPA knows of no U.S.

airports at which fixed-gantry systems are in use today. 

In the typical fixed-gantry system, aircraft taxi onto the gantry pad and nozzles

mounted on the gantry frame spray the aircraft with hot deicing fluid. The nozzles are controlled

by computers that are programmed to deliver the appropriate amount of fluid uniformly over the

entire aircraft for a variety of aircraft types and sizes. The deicing process takes approximately 8

to 12 minutes (5). Runoff is collected either in gutters or trench drains and pumped to storage

tanks for treatment, recycling, or disposal (14). Gantry systems are typically located on taxiways

near the end of the principal departure runway, reducing the time between aircraft deicing and

take-off (3). 
Section 6.0 - Pollution Prevention

6-10

Deicing Systems AB (DSAB), based in Kiruna, Sweden, is a leading manufacturer

of fixed-gantry deicing systems. DSAB installed its gantry system at the Munich Airport in

Germany in 1992 at a cost of approximately $5 million. The system consists of a computercontrolled, movable steel frame fitted with nozzles. The frame passes over the parked aircraft

while the computer controls the operation of the nozzles, starting and stopping the flow from each

nozzle as appropriate, depending of the type of aircraft. The speed of the gantry can be adjusted

to suit prevailing weather conditions. The gantry is 70 meters wide and 21 meters high and can

deice aircraft ranging in size from the Fokker 100 to the Boeing 747-400. The Munich system

also includes a collection system for spent aircraft deicing fluid. The collected runoff is sent to an

on-site glycol recycling facility also operated by DSAB (5). 

In addition to Munich, DSAB has installed its gantry system at the Kallax Airport

in Lulea, Sweden and the Standford Field Airport in Louisville, Kentucky. United Parcel Service

(UPS) purchased the DSAB gantry for its hub operations at Stanford Field Airport in 1988 at a

cost of approximately $6 million. The system purchased by UPS was designed to deice Boeing

727s, Boeing 757s and McDonnell Douglas DC-8s (15).

An alternative gantry system, called the Whisper WashTM, has been developed by

Catalyst and Chemical Service, Inc. The Whisper WashTM is a portable deicing system that uses

both deicing fluid and high-pressure hot air to deice/anti-ice aircraft. The system consists of

adjustable, cantilevered arms mounted on two modified flat-bed trailers. To accommodate

different types of aircraft, the height of the arms is adjusted using hydraulic jacks. Each arm

supports two sets of nozzles; one set delivers high-pressure hot air while the other delivers lowpressure deicing fluid. The nozzles used to deliver the deicing fluid are specially designed lowshear nozzles, which can be used to apply Type IV fluids as well as Type I fluids. The Whisper

WashTM system can also be operated in an air-only mode to remove light snow. According to the

manufacturers, Whisper WashTM can reduce ADF usage by up to 70% and can deice an aircraft in

less time than is required for convention deicing using deicing trucks. Two versions of the system

are currently available: a large system capable of handling wide-bodied aircraft and a small system

capable of deicing general aviation aircraft and commercial narrow-bodied aircraft. The system
Section 6.0 - Pollution Prevention

6-11

costs $1.2 million, with annual maintenance and labor costs of approximately $209,000. The

manufacturer also offers an optional ADF-containment system consisting of a perforated pipe

installed around the perimeter of the deicing area, which drain to sumps. Currently, no

commercial application of the Whisper WashTM system is known (5,6).

Proponents of the computer-controlled gantry systems assert that these systems:

(1) quickly and efficiently deice aircraft using the minimum volume of aircraft deicing fluid, (2)

can be operated by personnel with minimum training and experience, and (3) can collect as much

as 80% of the deicing fluid sprayed (5). Despite these purported advantages, fixed-gantry

systems are not popular with airlines or airport authorities. Airports are reluctant to invest in

fixed-gantry systems because they require a relatively large capital investment and require

considerable space that cannot be converted to other uses during good weather conditions. 

Airlines dislike fixed gantries because they can cause bottlenecks and delay aircraft departure. 

Some users argue that gantry systems actually apply more deicing fluid than necessary because

they deice aircraft indiscriminately, including areas that may not require deicing. In addition,

gantry systems cannot deice engine inlets, the undercarriage, or the underside of aircraft wings,

making it necessary for airlines to perform additional deicing using traditional deicer trucks (5). 

According to recent reports, dissatisfaction with the performance of their fixed-gantry systems

prompted UPS and some European airports to dismantle them. 

6.2.5 Infrared Aircraft Deicing Technology 

In recent years, a new method of aircraft deicing has been developed that relies on

infrared radiation. The leading manufacturers of infrared-based aircraft deicing systems are

Radiant Energy Corporation (formerly Process Technologies, Inc.) and Infra-Red Technologies,

Inc. Radiant Energy markets a fixed-hangar deicing system known as InfraTekTM, while InfraRed Technologies markets a mobile system known as Ice CatTM. Both systems have the potential

to greatly reduce the amount of glycol-based fluids used for aircraft deicing. Neither system is

widely used by airlines or airports, although the InfraTekTM system is currently in commercial use
Section 6.0 - Pollution Prevention

6-12

at three U.S. airports. A third system, under development by Sun Lase Inc., is designed to use

computer-controlled infrared lasers to deice aircraft. Each system is described in detail below.

InfraTekTM

InfraTekTM was developed under a Cooperative Research and Development

Agreement between Radiant Energy and the FAA. Under the agreement, Radiant Energy

developed the system and FAA provided expertise, advice, and test aircraft. A prototype was

tested at Rochester International Airport in February 1996. Tests conducted by the FAA in

March 1996 demonstrated that the InfraTekTM system could deice a Boeing 727 in six minutes,

the approximate time required to deice an aircraft using conventional fluids (17). Additional

testing conducted by the FAA and Radiant Energy showed that the infrared radiation did not

damage aircraft components. The FAA measured aircraft surface temperatures during deicing and

found that they never exceeded 94E F. Based on these results, the FAA approved deicing/antiicing procedures that use the InfraTekTM system for commercial aircraft in 1997 (18). 

The InfraTekTM system consists of an open-ended, hangar-type structure with

infrared generators suspended from the ceiling. The infrared generators, called Energy Processing

Units (EPUs), are fueled by natural gas. The infrared wavelengths are targeted to heat ice and

snow, while minimizing the heating of aircraft components. The energy and wavelength

generated by the EPUs can be adjusted to suit aircraft type. The system, operated similarly to a

car wash, is controlled by computer and is designed to be operated by one person. Prior to

deicing, the hangar floor is heated for 30 minutes to facilitate the melting of ice from aircraft

landing gear and the underparts of the wings and fuselage. Once the floor is heated, the system is

ready to receive aircraft. Aircraft taxi or are towed into the open-ended hangar immediately

before takeoff. Typically, a six-minute cycle is used, which includes two minutes at full EPU

power followed by four minutes at half power. The cycle time can be shortened for aircraft

covered with a light frost. 
Section 6.0 - Pollution Prevention

6-13

Although the system can deice aircraft, it cannot provide anti-icing protection.

When the ambient temperature is below freezing, precipitation can rapidly freeze on aircraft

surfaces after it leaves the InfraTekTM hangar. Consequently, anti-icing fluid is applied to the

aircraft when necessary to protect the aircraft during taxiing and takeoff. In addition, a small

volume of deicing fluid may be required to deice areas of the aircraft not reached by the infrared

radiation, including the flap tracks and elevators. While the InfraTekTM system does not

completely eliminate glycol-based fluids, it greatly reduces the volume required. Radiant Energy

estimates that the system reduces the volume of glycol-based deicing fluids applied to aircraft by

approximately 90% (19). InfraTekTM is reportedly less effective with snow (as compared to ice),

where the crystal structure of the flakes is thought to diffuse and reflect the infrared radiation

rather than absorbing it (3). Radiant Energy is, therefore, considering adding blowers to remove

loose snow from aircraft surfaces and improve efficiency. 

The first commercial InfraTekTM system was installed at Buffalo-Niagara

International Airport in March 1997 and is used for deicing general aviation and commuter

aircraft. The hangar installed at Buffalo is 42 feet high, 111 feet wide, and 126 feet long and is

capable of deicing aircraft as large as the ATR 72. In bad weather, it can deice four or five

aircraft per hour (20). Customers are charged a fixed fee based on the size of their aircraft (i.e.,

wing span and fuselage length), as opposed to conventional deicing using Type I fluids, where

charges are based on the volume of fluid applied. Customers prefer the fixed-fee payment

structure because it enables them to budget for winter operations more accurately. Due to the

success of the InfraTekTM system, Buffalo-Niagara International Airport is considering installing a

larger system capable of handling commercial jets and cargo aircraft. 

Radiant Energy installed its second commercial InfraTekTM system at the Oneida

County Airport in Rhinelander, Wisconsin in February 1998. This system is similar in size to the

one installed at Buffalo-Niagara International Airport, but is slightly taller, allowing British

Aerospace 146 commuter aircraft to be deiced (21). A third InfraTekTM system has been installed

at Newark International Airport by Continental Airlines for use during the 1999-2000 winter. 

This system is capable of deicing narrow-bodied commercial aircraft as large as the Boeing 737,
Section 6.0 - Pollution Prevention

6-14

and will be used primarily by Continental Airlines, although general aviation and other commercial

airlines have also expressed interest.

In addition to reducing fluid use, deicing using the InfraTekTM system reportedly

costs less than traditional deicing with deicing agents. InfraTekTM reportedly deices a Boeing 727

for under $350, compared with the cost of approximately $5,000 for deicing the same aircraft

with glycol-based fluids (2). 

Radiant Energy markets several different hangar sizes for the InfraTekTM system. 

The smallest system is designed to handle small general aviation and corporate aircraft, while the

largest system is designed to handle large passenger jets and cargo aircraft. The largest system

currently available is 95 feet high, 275 feet wide, and 320 feet long, which can accommodate

aircraft as large as the Boeing 747 (19). The capital cost of the InfraTekTM system depends on

the size of the hangar and ranges from $1 million to $4 million (5). 

The principle disadvantages of the InfraTekTM system are its physical size and

aircraft processing capacity. Land-locked airports located in urban areas may have difficulty

finding sites for the InfraTekTM system, particularly since the selected site must both comply with

FAA regulations and be convenient for aircraft taxiing to active runways. Airlines worry that the

system’s limited processing capacity will cause bottlenecks, resulting in unnecessary delays. 

While airport-wide implementation of the InfraTekTM system may be impractical at large airports

with heavy traffic volumes, implementation may be practical at smaller airports that do not have

congestion problems or by some tenants at larger airports (e.g., commuter airlines, general

aviation). Airlines are also concerned about the potential for melted precipitation to refreeze in

aerodynamically quiet areas, possibly resulting in the wing flaps and elevators malfunctioning. 

Although Radiant Energy reports that it has not seen any evidence that refreezing occurs in these

areas, the company plans to undertake a test program with APS Aviation, Inc. to study the issue

(22). 
Section 6.0 - Pollution Prevention

6-15

Ice CatTM

The Ice CatTM system is a mobile, truck-mounted system that uses infrared

radiation to remove frost, ice, and snow from aircraft surfaces. Infrared radiation is provided by

an array of flameless infrared emitters (i.e., catalytic heaters) fueled by natural gas, propane, or

butane. The infrared emitters are mounted on an articulated boom fitted to a specially designed

truck. The boom lifts and positions the infrared emitters approximately 2 to 5 feet above the

aircraft surface. Each unit is computer controlled. Depending on the size of the aircraft, one or

two Ice CatTM trucks may be used to deice an aircraft. According to the manufacturer, the

deicing process requires approximately 6 to 10 minutes to complete, during which infrared

radiation melts ice and snow accumulated on the aircraft and raises the temperature of the aircraft

skin. By raising the temperature of the aircraft skin, Ice CatTM temporarily prevents residual

surface water and/or precipitation from freezing on aircraft surfaces. Sensors mounted on the

boom monitor the surface temperature of the aircraft to ensure it never exceeds 140E F (23). 

Infra-Red Technologies sponsored a demonstration of the Ice CatTM in November

1997 at Kansas City International Airport where it was used to deice a Beechcraft Queen Air. 

Further tests were conducted in March 1998 at Kansas City where Ice CatTM was used to deice a

Boeing 727 and at the Pittsburgh National Guard Base where it was used to deice a military KC135 supertanker. Ice CatTM has also been tested by Transport Canada using an Air Canada

Boeing 737 and Fokker F-428 (23). Infra-Red Technologies has continued to improve Ice CatTM

and recently added a spray system designed to apply a light coating of Type IV (anti-icing) fluid. 

Ice CatTM is reportedly a cost-effective alternative to deicing with traditional

glycol-based aircraft deicing agents. According to the manufacturer, Ice-CatTM can deice a

Boeing 737 for as little as $5 (23). The cost of the system is unknown, but is believed to be

comparable to that of traditional deicer trucks. 

Despite its purported advantages, no commercial application of the Ice CatTM

system is currently known. Although Ice-CatTM is equipped with temperature sensors, many U.S.
Section 6.0 - Pollution Prevention

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airlines are worried that it may damage aircraft by overheating the aircraft’s skin. In addition, the

large size of the infrared panels may make Ice-CatTM difficult to maneuver in the confined space

of the gate area. Airlines are concerned about the potential for collisions between Ice-CatTM and

parked aircraft.

Sun Lase Inc.

Sun Lase Inc. is currently developing an infrared laser-based system designed to

quickly and efficiently deice aircraft. The system will use a high-power, infrared (i.e., 10-micron

wavelength) laser beam to melt ice on aircraft surfaces. The laser beam will be generated by CO2

lasers and directed at the aircraft surface using mirrors. The mirrors will be controlled by

computer, allowing the laser beam to be moved across the aircraft in a predetermined manner. 

The computer will control the laser alignment and simultaneously monitor the thermal

temperature of the aircraft skin. The laser beam will cover a surface area of approximately 1

square meter and deliver an intensity of 2.5 Watts/cm . For safety, the laser beam will be 2

combined with red light to enable operators to observe the position of the beam. The lasers can

be mounted on a truck or on telescopic poles. The system is designed to be operated by one

person. Sun Lase has applied for a U.S. patent and is currently constructing a prototype (24).

6.2.6 Hot Water Aircraft Deicing

The FAA permits aircraft to be deiced using hot water followed by the application

of an anti-icing fluid when ambient air temperatures are above 27E F (3). None of the major U.S.

airlines currently use this method because they believe it would compromise the safety of

passengers and ground operations staff. Airlines are concerned about flash freezing and the

potential to build up thick layers of ice both on the aircraft and on the pavement. The water may

also enter and freeze on flap tracks, elevators, and other aircraft parts, potentially affecting

aircraft handling and performance. Water freezing in hoses, nozzles, and tanks when deicer trucks

are not in use is also a concern.
Section 6.0 - Pollution Prevention

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6.2.7 Varying Glycol Content to Ambient Air Temperature

Although Type I fluid can be purchased in a prediluted ready-to-use form, many

airlines and fixed-base operators prefer to purchase their Type I fluid in concentrated form

(approximately 90% glycol) and dilute to a glycol concentration appropriate to the local weather

conditions (13, 25). Some airlines mix Type I fluids specific to each deicing event based on

prevailing weather conditions, thereby minimizing the amount of deicing fluid sprayed. For

example, Delta Airlines uses a “Local Area Expert,” a person well trained in deicing operations,

to determine the glycol concentration appropriate for the prevailing temperature. This practice

enables Delta to use Type I fluids containing as little as 30% glycol, rather than the typical 50/50

glycol and water mixture, when weather conditions are mild. 

A similar practice is used at Denver International Airport where the airport’s FBO

supplies airlines with Type I fluids containing glycol concentrations that are appropriate for the 

ambient air temperature. The FBO purchases Type I fluid in a concentrated form, stores it in

20,000-gallon storage tanks at the airport’s glycol recycling facility, and mixes it with water in a

10,000-gallon tank equipped with a mixer. The concentrated fluid and water are metered into the

mixing tank in the appropriate proportions and a built-in densitometer is used to verify the glycol

concentration. 

Due to storage problems and concerns about human error, some airlines prefer to

mix Type I fluids to meet historical temperature minimums. Northwest Airlines, for example,

analyzes historical temperature data for a given airport and selects a glycol content to match the

lowest temperature the airport is likely to experience. This practice may result in fewer mistakes

and is particularly suited to some smaller airports that lack storage for preparing multiple-strength

solutions. 

Where possible, the U.S. Air Force also adjusts the glycol concentration of its

aircraft deicing fluids based on ambient air temperatures. At some bases, the Air Force uses

deicer trucks with two-chamber tanks: one for concentrated aircraft deicing fluid and the other for
Section 6.0 - Pollution Prevention

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heated water. The flow rate from each tank can be adjusted to alter the glycol concentration of

the fluid as it is applied to aircraft. One disadvantage of the two-chamber deicer trucks is that the

water may freeze when the trucks are not in use. This problem caused personnel at some

northern bases to remove the baffles and create a single tank in which the deicing fluid can be

mixed to meet prevailing or anticipated weather conditions prior to application (13).

6.2.8 Enclosed-Basket Deicing Trucks

Airlines typically use open-basket configurations, called “cherry pickers,” to apply

ADF. The open baskets provide little protection for personnel, who are frequently sprayed by

aircraft deicing and anti-icing fluids. An enclosed-basket design is now available that improves

operator working conditions (2). By enabling operators to get closer to the aircraft, the enclosed

basket reportedly reduces over-spray and helps to minimize the volume of fluid used to deice

aircraft. As a result, some airlines have reported 30% reductions in aircraft deicing fluid usage. 

As a result of these benefits, many U.S. airlines now employ a fleet of enclosed-basket deicing

trucks at their hubs and larger stations. Several companies manufacture the enclosed-basket

deicing trucks, including Simon Aviation Ground Equipment, Elberta Industries, Premeir, and

FMC (5).

6.2.9 Mechanical Methods

The volume of ADF applied to aircraft can be minimized by mechanically deicing

the aircraft prior to chemical deicing (2). The U.S. Air Force, for example, uses brooms,

squeegees, and ropes to remove ice and snow from aircraft surfaces (26, 27). These methods are

more effective at removing snow rather than ice. When performed incorrectly, they can damage

aircraft antennas and sensors. Mechanical methods are generally only practical for smaller

aircraft; for large aircraft, they can be prohibitively time-consuming and labor intensive. Despite

these drawbacks, Northwest Airlines uses brooms fitted with long handles to remove snow from

large passenger aircraft. This method is used only in the early mornings, when it is least

disruptive to Northwest’s departure schedule. 
Section 6.0 - Pollution Prevention

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6.2.10 Aircraft Deicing Using Solar Radiation

At several U.S. Air Force bases, aircraft parked on ramps are oriented to maximize

the melting of accumulated snow and ice by sunlight. This method reduces the volume of aircraft

deicing fluid used during the winter season, but is practical only for general aviation and certain

military flights that can be delayed without negative economic or operational impacts (13, 26).

6.2.11 Hangar Storage

Many general aviation aircraft and some commuter and military aircraft are stored

in hangars overnight and during storm events, eliminating the need for aircraft deicing. In

addition, heated aircraft hangars are sometimes used to deice aircraft. In either case, anti-icing

may be necessary in certain weather conditions to prevent ice and snow from accumulating on

aircraft surfaces during taxiing and takeoff. After leaving the hangar, aircraft are anti-iced by

spraying with a small volume of glycol-based anti-icing fluid (typically 2 gallons for very small

aircraft). Because of the small volumes applied, the volume of ADF-contaminated wastewater

generated is much less than would have been generated had aircraft been stored outdoors. The

Tri-State Airport in Huntington, West Virginia, for example, estimates that their 84-foot-by-120-

foot heated aircraft hangar saved approximately 1,500 gallons of Type I fluid last year and

estimates that a new 70-foot-by-100-foot heated hangar will save an additional 1,000 gallons of

Type I fluid during the 1999-2000 deicing season. Tri-State Airport handles approximately

46,000 operations each year of which approximately 70% are conducted by general aviation

aircraft that are easily stored in aircraft hangars. 

6.2.12 Aircraft Covers

Where hangar space is not available, aircraft covers or blankets are sometimes

used as an alternative method to minimize frost, ice, and snow accumulation on aircraft surfaces

(28). Aircraft covers are typically used for small general aviation aircraft to protect the wings,

tail, and engine inlets. There are currently two types of covers available: solid and mesh covers. 
Section 6.0 - Pollution Prevention

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Solid covers are made from nylon or canvas and should not be used in strong winds. In cold

weather, they tend to become hard and freeze to the wings, making them difficult to remove. 

Mesh covers are made from a very fine mesh fabric and are designed for use in windy conditions. 

They are easier to remove in cold weather but provide less protection, tending to leave residual

ice on wing surfaces (29). 

Northwest Airlines experimented with aircraft covers for large passenger aircraft,

but was dissatisfied with their performance. Northwest found them to be relatively easy to install,

but difficult and time-consuming to remove as they become hard and inflexible when cold. In

some instances, condensation trapped between the wing and the cover froze, binding the cover

tightly to the wing surface. In addition, covers that came in contact with the pavement picked up

grit, which damaged aircraft surfaces as the covers were pulled into place. Based on this

experience and the high cost of the covers (approximately $10,000), Northwest concluded that

aircraft covers are impractical for use on large passenger aircraft. 

6.2.13 Thermal Blankets for MD-80s and DC-9s

The MD-80 and DC-9 aircraft are particularly prone to icing. Fuel stored in tanks

located below the aircraft’s wings becomes super-cooled during flight. Ice forms on wing

surfaces as the aircraft descends and lands, and may form on days when the ambient air

temperature is well above freezing. This ice is removed prior to takeoff by applying a small

volume of ADF, typically 25 to 50 gallons, in a process known as “clear ice” deicing. Although

the volume of fluid used is small, “clear ice” deicing is regularly performed on these aircraft

throughout the winter months. Consequently, many airlines operating large fleets of MD-80s and

DC-9s are attempting to eliminate the need for “clear ice” deicing by retrofitting these aircraft

with specially designed thermal blankets. The blankets are bonded to the wing surface and consist

of nickel-plated carbon fibers sandwiched between fiberglass layers. The blankets are

manufactured by Allied-Signal Aerospace and cost approximately $35,000 (2). The airlines are

pleased with the overall performance of the blankets and believe they significantly reduce the

volume of aircraft deicing fluid used for “clear ice” deicing of MD-80s and DC-9s.
Section 6.0 - Pollution Prevention

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6.2.14 Ice-Detection Systems

Pilots and aircraft deicing crews often have difficulty detecting ice on aircraft

wings, particularly at night when visibility is poor. Consequently, aircraft are deiced whenever ice

is suspected to be present. This conservative approach is appropriate from a safety standpoint,

but may lead to unnecessary application of ADFs. One solution is the use of ice-detection

systems. Although some ice-detection systems are known to have difficulty detecting ice on

painted surfaces and composite materials, most systems improve safety while increasing the

efficiency of aircraft deicing/anti-icing operations. 

There are currently two types of ice-detection systems available: a remote system

and a wing-mounted system. SPAR Aerospace markets a remote detection system developed by

Cox and Company. The system is known as the Contamination Detection SystemTM (CSD-1) and

uses an infrared camera to detect ice and evaluate the integrity of anti-icing fluids on aircraft

surfaces (4). The camera can be used at distances of 58 feet from the aircraft. The CSD-1 is

reported to be capable of detecting clear ice films as thin as 0.01 inches and can detect ice crystals

forming in Type IV fluids (25). The system costs approximately $60,000 (5).

Allied-Signal Aerospace has developed a wing-mounted system known as the

Clean Wing Detection SystemTM. This system uses sensors mounted in the upper surface of the

wing to detect surface contamination. The sensors can identify the type of contamination (e.g.,

frost, ice, snow, and deicing/anti-icing fluid) and measure its thickness (4). The system is also

designed to measure the performance of anti-icing fluids and can determine when additional

deicing/anti-icing is warranted. The cost of this system depends on the number of sensors

installed and ranges from $50,000 for four sensors to $75,000 for eight sensors (2). 

BF Goodrich, a leading manufacturer of in-flight ice detectors, markets a remote

detection system, called the IceHawkTM Wide Area Ice Detector, which uses an infrared light

beam to detect ice, snow, and frost on aircraft surfaces. The IceHawkTM is designed to detect

frozen contamination up to 60 feet from the aircraft and has been approved by the FAA to replace
Section 6.0 - Pollution Prevention

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the tactile inspection. The system works by scanning the aircraft surface with a polarized infrared

beam. The system analyzes the polarization of the reflected signal and generates an image on a

color, LCD monitor. Infrared signals reflected from surfaces contaminated with ice, frost or snow

are unpolarized. These areas are displayed on the monitor in red. The system can detect ice

covered by deicing and anti-icing fluids and can be used in any lighting or weather conditions

without recalibration. The units are portable and may be either handheld or mounted on deicer

trucks and are currently being used by Delta Airlines, Federal Express, and the U.S. Air Force. 

BF Goodrich is also developing an onboard version of the IceHawkTM in which the sensor is

installed above a passenger window in the fuselage at a position behind the wing. The company

has tested a prototype of the new system on an FAA Boeing 727 last winter and plans to conduct

additional testing during the 1999-2000 winter (30).

6.2.15 Airport Traffic Flow Strategies and Departure Slot Allocation Systems

More effective airport management plans and better communication during storm

events can help avoid unnecessary repeated application of ADF, particularly at the busier and

more congested airports. The FAA recommends that airport management collaborate with the

airlines, FBOs, air traffic control, and other interested parties to develop communication

procedures and traffic flow strategies for winter operations. Winter traffic flow strategies can

identify the shortest taxiing routes and minimize holdover times for deiced aircraft, thereby

reducing or eliminating the need for repeated deicing/anti-icing and reducing the amount of fluid

used for secondary deicing (31). 

Some airports have instituted a departure slot allocation system to reduce delays

caused by runway congestion and enable aircraft to depart immediately after being deiced. Using

this system, air traffic control estimates the number of departures possible based on the particular

weather conditions and assigns departure times (slots) to aircraft before they are deiced. Since

the number of departures is normally reduced during snow and ice conditions, the available

departure slots are usually allocated to airlines based on their percentage of the total flights

scheduled that day. For example, on a typical day, the schedule may have 200 flights, with 70%
Section 6.0 - Pollution Prevention

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of the departures by airline A, 25% by airline B, and 5% by airline C. If the departure rate is

reduced to 20 aircraft every hour due to bad weather, then air traffic control will assign 70% of

available departure slots (14 slots) to airline A, 25% (5 slots) to airline B, and 5% (1 slot) to

airline C. This practice is particularly beneficial at large, congested airports where it enables

airline operations personnel to coordinate the deicing of an aircraft with its allocated takeoff time. 

One problem encountered by airports using the slot allocation system is the

difficulty of enforcing compliance. While most airlines voluntarily comply with the slot allocation

system, aircraft from some airlines start taxiing even though they have not been allocated a

departure slot. For the slot allocation system to work effectively, air traffic control must police

the system by denying errant aircraft takeoff clearance. 

Several airlines cancel inbound flights prior to or during severe weather conditions. 

This traffic flow strategy reduces the volume of fluid used by reducing the number of aircraft

requiring deicing. For example, at General Mitchell International Airport in Milwaukee,

Wisconsin, some airlines cancel flights and transport passengers by bus to nearby Chicago O’Hare

International Airport. 

6.2.16 Personnel Training and Experience

An important factor affecting the efficiency of aircraft deicing/anti-icing operations

is the training and experience of personnel involved in aircraft deicing/anti-icing. Most airlines

and FBOs do not have employees dedicated to aircraft deicing/anti-icing and use ground

operations personnel (e.g., baggage handlers, mechanics) or hire temporary staff. Due to low pay

and poor working conditions, employee turnover is typically high. Consequently, a large portion

of aircraft deicing/anti-icing staff, particularly at larger airports, is newly hired and trained each

year. Due to inexperience and concerns about the consequences of inadequate deicing/anti-icing,

new hires often spray more fluid than necessary. While the eight hours of FAA-mandated training

received by new hires ensures the safe operation of aircraft, several years of experience may be

necessary for an employee to become efficient at aircraft deicing/anti-icing. Well-trained and
Section 6.0 - Pollution Prevention

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experienced deicing/anti-icing personnel improve the efficiency of aircraft deicing/anti-icing

operations and minimize the volume of fluid used, while ensuring passenger safety.

The training and experience of airport personnel may also affect the efficiency of

aircraft deicing/anti-icing operations. Airport personnel are typically responsible for clearing

taxiways, gate areas, ramps, aprons, and deicing pads. When these areas are not adequately

cleared, snow and ice accumulate on the undercarriage and the underside of aircraft during taxing

and must be removed prior to takeoff. As a result, poor winter maintenance of airfields tends to

increase the volume of aircraft deicing fluids applied by making it necessary to perform secondary

aircraft deicing at departure runways.

6.2.17 Other ADF Minimization Practices

Additional sources of ADF discharges to the environment include spills from

overfilling deicer truck tanks and leaks from worn or defective fittings on deicer trucks and other

application equipment. These sources of ADF can be greatly reduced by equipping deicer trucks

with dripless fittings and automatic filling shutoff valves. At Albany International Airport, all

deicer trucks are required to be fitted with sight gauges and automatic filling shutoff valves that

prevent tanks from being filled above 80% of their capacity. The cost of retrofitting existing

deicer trucks was approximately $250 per truck (32).

Unnecessary releases of ADF to the environment can also be reduced by locating

ADF storage tanks within the boundaries of the designated aircraft deicing/anti-icing collection

and containment areas. At Denver International Airport, for example, deicer trucks are refilled

from ADF storage tanks located on the aircraft deicing/anti-icing pads. Since the deicer trucks do

not leave the containment area, any spills or leaks from defective fittings or overfilled tanks are

collected along with the other ADF-contaminated storm water.
Section 6.0 - Pollution Prevention

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6.2.18 Glycol Minimization Methods Currently Under Development

Foster-Miller, Inc. is developing a surface treatment or coating that would provide

anti-icing protection by preventing ice and snow from adhering to aircraft surfaces. Theoretically,

this technology combined with the forced-air deicing system discussed in Section 6.2.3 could

greatly reduce the need for glycol-based ADFs by enabling snow and ice to be easily blown from

aircraft surfaces. Foster-Miller is currently evaluating possible aircraft surface coatings. The

project is funded by the Department of Transportation’s National Center for Environmental

Research and Quality Assurance (33). 

Professor Victor Petrenko of Dartmouth’s Thayer School of Engineering is

developing an alternative deicing technique that uses electricity to loosen ice from aircraft

surfaces. The electricity disrupts the orientation of surface water molecules, breaking bonds

between the ice crystals and the metal substrate. Similar to the surface coatings discussed above,

this method would rely on forced-air to blow snow and ice from aircraft surfaces. To date, the

method has only been demonstrated in the laboratory using steel and other solid materials. 

Additional research will be necessary to determine whether the electrical current used to loosen

the ice will interfere with sophisticated aircraft navigational equipment and electrical systems.

Polaris Thermal Energy Systems, Inc., in association with Transport Canada and

Continental Airlines, is investigating the possibility of introducing heated fuel in wing fuel tanks to

prevent frost, ice, and snow from forming on wing surfaces when the aircraft is on the ground. 

Polaris believes this method will be especially advantageous for MD-80s and DC-9s, where fuel

stored under the wings tends to become super-cooled during flight, causing clear ice to form on

the surface of the wings after the aircraft has landed. In preliminary tests conducted by Polaris

and Transport Canada, the method has proven effective in minimizing the volume of deicing fluids

required. One test, conducted by Polaris in March 1997, demonstrated that the method could,

under certain weather conditions, eliminate the use of conventional glycol-based deicing fluids. 

The test was conducted at Cleveland’s Hopkins International Airport using an MD-80 owned by

Continental Airlines. The aircraft arrived at the airport at 1:08 a.m. with approximately 8,000
Section 6.0 - Pollution Prevention

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pounds of super-cooled fuel stored in its tanks. Polaris introduced 1,000 pounds of heated fuel

(heated to approximately 85E F) into the aircraft’s fuel tanks at 2 a.m. Polaris monitored the wing

temperature using infrared photography and found the surface temperature rapidly increased by

10E F. Additional heated fuel was added at 2:20 a.m. and 3:00 a.m., raising the average wing

surface temperature to 79E F. Although the ambient temperature was about 18E F and a light to

heavy snow fell during the early morning hours, the aircraft did not need deicing with

conventional fluids prior to its scheduled 7:40 a.m. departure. Polaris estimates the cost of

heating the fuel was approximately $40 (34). While this method may reduce discharges of ADF

to U.S. surface waters by reducing the overall volume of ADF applied to aircraft, it may result in

additional cross-media impacts (e.g., increased air emissions).

6.3 Aircraft Deicer/Anti-icer Collection and Containment Methods

In response to EPA’s 1990 storm water program and state and local requirements,

many U.S. airports are collecting wastewater from aircraft deicing/anti-icing operations to prevent

or minimize discharges at storm water outfalls. Airports use a variety of collection methods,

including gate and ramp area drainage collection systems, storm sewer plugs, designated aircraft

deicing pads, temporary aircraft deicing pads, storm drain valves, and specially designed glycolvacuum vehicles. Individual airports often rely on a combination of these collection strategies,

varying the collection method to suit tenant requirements, utilize existing infrastructure, or adapt

to site-specific constraints. Collected wastewater may then be processed to recycle/recover

glycol, treated on site, discharged to a publicly owned treatment works (POTW), or a

combination of these methods. The following subsections describe in detail the various

wastewater collection methods used by the industry. Federal aid from the FAA-administered

Airport Improvement Program may be used to finance construction of wastewater collection

systems and storage facilities (35). Funding for this program, however, is limited and

deicing/anti-icing wastewater collection projects must compete with other important airport

improvement projects, such as resurfacing airport runways, upgrading runway lighting systems,

and constructing new taxiways.
Section 6.0 - Pollution Prevention

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6.3.1 Aircraft Deicing Facilities

As airport authorities began to grapple with the problems of collecting wastewater

from aircraft deicing operations and meeting NPDES permit limits, they soon realized that

wastewater could be collected more efficiently by confining aircraft deicing operations to small,

designated areas where provisions for containment and collection could be installed. As a result,

several U.S. airports constructed specially designed aircraft deicing facilities called aircraft deicing

pads. Denver International Airport, Salt Lake City International Airport, Pittsburgh International

Airport, Baltimore Washington International Airport, Dayton International Airport, MinneapolisSt. Paul International Airport, and Detroit Metropolitan Wayne County Airport are currently

using deicing pads. In Canada, Toronto’s L.B. Pearson International Airport and Montreal’s

Dorval International Airport have constructed large deicing facilities consisting of multiple deicing

pads.

In general, aircraft deicing pads consist of a concrete or asphalt platform, a

drainage collection system, and a wastewater storage facility. The platform is graded and

sometimes grooved to channel wastewater to the drainage collection system. The collection

system typically consists of trench or square drains connected to underground storm water pipes,

which are usually fitted with diversion boxes to allow ADF-contaminated wastewater to be

diverted to a wastewater storage facility during the deicing season. The wastewater is stored in

detention ponds, tanks, or underground concrete basins. The pads are typically designed to

accommodate more than one aircraft at a time and are usually divided into individual aircraft

deicing bays. Some pads also include snow melters (discussed in Section 6.3.7) for disposal of

ADF-contaminated snow collected on and around the deicing pad. The resultant wastewater is

collected by the pad’s drainage collection system and diverted to the wastewater storage facility.

Aircraft are deiced on the pads using conventional deicer trucks or fixed-boom

applicators. To avoid collisions, deicer trucks are parked in designated areas when aircraft are

entering or exiting the pad. Fixed-boom applicators are less popular with airlines and are known

to be installed at only three aircraft deicing pads in the U.S. (one pad at Denver International
Section 6.0 - Pollution Prevention

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Airport and two pads at Pittsburgh International Airport (20)). When not being used for deicing,

the pads often serve as aircraft parking aprons or holding pads.

Since most commercial aircraft are able to taxi prior to deicing and can be deiced

with their engines running, aircraft deicing pads may, upon approval by FAA, be located on

taxiways, on cargo or general aviation ramps, near departure runways, or adjacent to passenger

terminals. The FAA recommends that pads should be constructed to accommodate the largest

aircraft the airport serves (i.e., widest wingspan and longest fuselage) and should have sufficient

capacity to handle peak periods of aircraft departures without causing departure delays (35).

Deicing pads may also require additional personnel for monitoring aircraft movements on the pad

and managing wastewater collection. The number, location, and size of aircraft deicing pads

required for a particular airport depends on the number of operations, the types of aircraft using

the airport, the meteorological conditions typically experienced, the availability of land, and the

physical layout of the airport. For some airports, deicing pads may be unnecessary due to

efficient ADF-collection systems installed at the passenger terminals and cargo ramps (see Section

6.3.2). 

The largest and most technologically advanced aircraft deicing pads are located in

Canada at Montreal’s Dorval International Airport and Toronto’s L.B. Pearson International

Airport. These airports have constructed centralized aircraft deicing facilities that include storage

tanks and filling stations for aircraft deicing/anti-icing agents and control towers for monitoring

deicing operations and controlling traffic flow. The Montreal pad accommodates up to seven

aircraft at a time and has a laser guidance system to assist pilots in maneuvering and parking

aircraft on the deicing pad (36). 

The Toronto pad consists of four deicing bays, but is currently being expanded to

six bays. Once the expansion is completed, the deicing facility will be able to accommodate up to

six Boeing 747s and will cover an area of 65 acres. Each deicing bay is approximately 328 feet

wide and 780 feet long. A high-density polyethylene liner, installed underneath the deicing bays,

collects any fluid that seeps through the concrete pad. Inset lighting assists pilots in positioning
Section 6.0 - Pollution Prevention

6-29

aircraft on the pad, while surveillance cameras are used to record activities on the pad. An

electronic sign board system provides pilots with deicing operational information, minimizing

verbal communication requirements. Wastewater from aircraft deicing/anti-icing operations is

collected in 14 diversion vaults, which are equipped with automated diversion valves. A pump

located in the bottom of each diversion vault pumps samples of the wastewater to a small, on-site

laboratory, where the glycol concentration is measured. If the glycol concentration is less than

the Canadian voluntary guideline of 100 mg/L (see Section 13.3.1), the wastewater is discharged

through the storm water drainage system. If the glycol concentration is greater than 100 mg/L,

the operator diverts the wastewater to one of three underground storage tanks. The storage tanks

have a combined capacity of approximately 3.5 million gallons. The stored wastewater is either

trucked to a glycol recycling plant or discharged to a local POTW (37). 

Although the principal environmental advantage of deicing pads is their ability to

collect a high percentage of the aircraft deicing fluid sprayed, the wastewater they collect has a

high glycol content, an important advantage for airports considering glycol recovery/recycling. 

For example, at Denver International Airport, aircraft deicing pads collect wastewater with glycol

concentrations of approximately 20 percent (20). By collecting wastewater with high glycol

concentrations, Denver’s aircraft deicing pads make its on-site glycol recycling economically

viable.

 

Aside from their environmental benefits, deicing pads provide several operational

and safety advantages. First, they allow aircraft to move away from the gate area so that arriving

flights have access to gates. Second, they allow for much more efficient spraying of aircraft,

especially for aircraft with wide wing spans, such as the new Boeing 777. Third, they ease ramp

and gate area vehicle congestion. Fourth, they improve safety and working conditions for

baggage handlers, maintenance engineers, and other airline personnel working in the gate area. 

Finally, they improve passenger safety by enabling aircraft to be deiced closer to the departure

runway, decreasing the time between deicing and takeoff and reducing the potential for an aircraft

to exceed its holdover time. 
Section 6.0 - Pollution Prevention

6-30

Despite these advantages, some airlines have been reluctant to use aircraft deicing

pads. Airlines are primarily concerned that aircraft deicing pads may create a bottleneck, resulting

in departure delays. To prevent unnecessary delays, the FAA recommends deicing pads be

constructed with bypass taxiways that allow aircraft not requiring deicing to proceed without

hindrance to active runways. Airports serving a wide range of aircraft types can often reduce

congestion by constructing separate aircraft deicing pads for general aviation, cargo, commuter

aircraft, and large passenger jets. For example, Pittsburgh International Airport has constructed

five aircraft deicing pads: two for large passenger jets, one for cargo carriers, and two smaller

pads for commuter aircraft (20). 

Airlines also complain of congestion on aircraft deicing pads caused by the

presence of deicer trucks from several different airlines. Currently, most passenger airlines deice

their aircraft using their own deicer equipment. The presence of multiple deicer trucks increases

the potential for collisions with aircraft or other airport vehicles. This problem can be solved by

air carriers allowing their aircraft to be deiced by a single carrier or a fixed-based operator. At

Dorval International Airport in Montreal, for example, aircraft deicing/anti-icing is performed

exclusively by the airport’s FBO, Aeromag 2000. Similarly, aircraft deicing/anti-icing at the L.B.

Pearson International Airport’s new central deicing facility is conducted by Hudson General

Aviation Services, Inc. However, due to liability issues and concerns over equitable access to

deicing pads, airlines often have difficulty agreeing on who should provide aircraft deicing

services at deicing pads and which fluid formulations should be used. These issues are particularly

difficult to resolve at airports that have no dominant carrier and a large number of competing

airlines. 

Although not limited to aircraft deicing pads, one environmental problem

encountered by airports is the tracking of aircraft deicing and anti-icing fluids from the pad onto

nearby taxiways and runways. This problem is caused primarily by fluids dripping from aircraft

after they have left the deicing pad, but may also be caused by jet blast, drippage from aircraft

undercarriages, and the wheels of airport vehicles carrying fluid across the pad’s threshold.
Section 6.0 - Pollution Prevention

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For some airports, deicing pads may be impractical due to their physical size and

capital and operational costs. The construction costs for aircraft deicing pads vary with the size

and complexity of the system. For example, Denver International Airport constructed three

deicing pads with drainage collection systems for approximately $2 million per pad (1). Dorval

International Airport’s pad, complete with storage facilities, new deicer equipment, laser guidance

system and control tower, cost approximately $22 million. 

6.3.2 ADF Collection Systems for Ramps and Passenger Terminal Gate Areas

At most airports, aircraft deicing operations are performed on aircraft parking

ramps or at the passenger terminal gates. To collect wastewater generated at these locations,

some airports have installed new collection systems or modified existing storm water drainage

systems. The typical collection system consists of graded concrete pavement with trench or

square drains connected to a wastewater storage facility via a diversion box. The storage facility

may consist of detention ponds (covered or uncovered), tanks, or underground concrete basins. 

The diversion box allows uncontaminated storm water to be diverted to storm water outfalls.

The construction or modification of drainage collection systems with their

associated underground piping, diversion boxes, and storage facilities can be extremely expensive,

especially for larger airports that have several passenger terminals and a large number of gates. In

addition to the expense, these projects are often disruptive to airline operations. Many U.S.

airports already experience delays due to congestion, and temporary gate closures would

exacerbate the situation. Similar to deicing pads, ADF may be tracked outside the containment

area onto nearby runways and taxiways. 

Because of the large drainage area typical of passenger terminals and aircraft

parking ramps, large volumes of very dilute wastewater are collected. Airports located in urban

areas may not have sufficient land available to construct storage facilities large enough to

accommodate the volume of wastewater generated. The relatively low glycol concentrations

typical of wastewater collected by these systems make glycol recycling/recovery difficult and
Section 6.0 - Pollution Prevention

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expensive; however, low glycol concentrations can be an advantage to airports that discharge 

their wastewater to a POTW.

The principal advantage of installing ADF collection systems at aircraft parking

ramps and passenger terminals is that they enable airports to collect wastewater from aircraft

deicing and anti-icing without requiring airlines to alter their winter operating practices. Many

airlines believe that deicing and anti-icing aircraft at these locations is an unavoidable part of

winter operations, because aircraft can be damaged by taxiing prior to being deiced. For example,

aircraft engines may be damaged by ingesting ice shed from aircraft surfaces during taxiing. 

Aircraft with engines mounted on the rear fuselage, such as the MD-80, are particularly at risk. 

Consequently, most airports with deicing pads (discussed in Section 6.3.1) allow airlines to

conduct some limited gate and ramp deicing. Several U.S. airports, such as Kansas City

International, Greater Rockford, Bradley International, Minneapolis-St. Paul International, and

Albany International, have installed new collection systems or modified existing storm water

drainage systems to enable them to collect ADF-contaminated storm water from these areas. 

Several example systems are described below. Additional information about ADF collection

systems, including the systems used at Dallas-Ft. Worth International and Albany Interntional

Airports, is provided in Section 7.1. 

Kansas City International Airport, Kansas City, MO (KCI)

Kansas City International Airport is currently constructing a new collection system

at its passenger terminals. The new system consists of trench drains strategically located 240 feet

from the face of the terminal buildings. Wastewater from aircraft deicing/anti-icing operations

combines with small amounts of storm water runoff, enters the trench drains, and is conveyed

through underground pipes to a two-celled, concrete storage basin. Due to the large size of the

drainage area, the storage basin was constructed with a capacity of 2 million gallons. The

collected wastewater is discharged at a controlled rate to a POTW. 
Section 6.0 - Pollution Prevention

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Greater Rockford Airport, Rockford, IL (RFD)

At the Greater Rockford Airport in Rockford, Illinois, UPS has constructed an

aircraft parking ramp with two separate drainage areas, each with its own collection system. Both

drainage collection systems are connected through diversion boxes to the airport’s treatment

facility and to the airport’s storm water outfall on the Rock River. The drainage system on the

southern part of the ramp drains approximately 33% of the UPS ramp. During the winter, aircraft

deicing/anti-icing operations are typically restricted to the southern part of the ramp. At peak

traffic times, such as the Christmas season, UPS can expand the area used for aircraft deicing/antiicing to the northern part of the ramp by diverting the wastewater from that area to the airport’s

treatment system (discussed in Section 7.2.1). The treatment system has a combined storage

capacity of 21 million gallons. 

The separate drainage areas provide UPS with maximum operational flexibility,

while also providing the airport with the flexibility needed to efficiently manage the wastewater

generated. The principal advantage of this design is that it enables the airport to minimize the

dilution of the wastewater during precipitation events by reducing the drainage collection area. 

Storm water that is not contaminated with ADF is discharged directly to the Rock River.

Bradley International Airport, Windsor Locks, CT (BDL)

Construction plans for a new passenger terminal at Bradley International Airport

near Hartford, Connecticut, include two independent drainage collection systems, one for clean

storm water and one for ADF-contaminated storm water. Rectangular drains (one for each

drainage system) will be installed side by side in the gate areas. During aircraft deicing

operations, the clean storm water drains will be closed using drain inserts (discussed in Section

6.3.4) to prevent ADF-contaminated storm water from entering the clean storm water drainage

system. Drains for the ADF-contaminated storm water drainage system will be opened, allowing

the wastewater to be collected in underground storage tanks. Although the dual drainage system

is expensive, airport personnel believe it will be more efficient and require less monitoring than
Section 6.0 - Pollution Prevention

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single drainage systems where contaminated storm water tends to remain in storm water pipes

long after deicing/anti-icing operations have ceased and be washed out during periods of heavy

rainfall.

Minneapolis-St. Paul International Airport, Minneapolis-St. Paul, MN 

(MSP)

Minneapolis-St. Paul International Airport has avoided the large capital

expenditures associated with construction of a new collection system by using existing

infrastructure to collect ADF-contaminated storm water. At this airport, storm water pipes

located at the passenger terminal are turned into temporary retention systems by inserting

specially designed compression plugs. The plugs are installed prior to the beginning of the deicing

season and removed in late spring. The contaminated storm water is pumped out periodically and

transferred by truck to the airport’s detention ponds. Careful management of the retention

systems enables the airport to collect enough wastewater with high glycol concentrations to make

glycol recycling/recovery economically viable. Inland Technologies, Inc., under a contract with

Northwest Airlines, currently operates an on-site glycol recycling/recovery system, which is

described in detail in Section 6.4. 

6.3.3 Temporary Aircraft Deicing Pads

Temporary aircraft deicing pads are specially designed platforms used to collect

contaminated wastewater generated during aircraft deicing and anti-icing operations. They are

constructed from reinforced rubber or polypropylene mats and sometimes use inflatable air or

foam berms to contain contaminated wastewater. The temporary pads cost less than permanent

structures, are portable, and can be assembled on taxiways close to departure runways. Although

EPA does not know of any U.S. airports using this collection method, four types of temporary

aircraft deicing pads are currently available and are discussed in detail below. 
Section 6.0 - Pollution Prevention

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Ro-MatTM

Ro-MatTM is manufactured by the Danish company A/S Roulunds Fabriker and

consists of a thick rubber mat that can tolerate temperatures ranging from -50E C to 50E C. The

mat is grooved and reinforced with steel cables. The grooves are designed to channel wastewater

to existing drainage systems, such as open trenches or trench drains, located at the sides of the

mat. The mat can be placed on an asphalt or concrete taxiway and can be moved if necessary. 

The Ro-MatTM costs approximately $22 per square foot (5, 38).

The Ro-MatTM is currently in use at Copenhagen International Airport in

Denmark, where it is located on a taxiway close to the departure runway. The system was

installed in 1992 at a cost of approximately $1.6 million, and consists of the Ro-MatTM, a drainage

collection system, and wastewater storage tanks. The system is reportedly capable of collecting

up to 75% of sprayed aircraft deicing fluid. The glycol concentration of the collected wastewater

is relatively high, typically ranging from 25.8% to 32.5% (5, 38).

LatimatTM

Environmental Cleaning Systems, Inc. has developed a containment pad system

called LatimatTM, which consists of a pad with inflatable air or foam berms. The containment pad

is portable and can be manufactured in a variety of sizes to meet customer requirements. The

largest LatimatTM available can accommodate a Boeing 747 aircraft (39).

Pure MatTM

Recovery Systems, Inc. manufactures a containment system similar to LatimatTM

called Pure MatTM. The Pure MatTM consists of a pump and a chemically resistant mat attached to

a flexible berm. The pump transfers wastewater from the containment area to a storage tank for

future treatment, recycling, or disposal. The system can be used for either aircraft deicing or

washing (5). 
Section 6.0 - Pollution Prevention

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Remote Aircraft Wash Platform and Portable Evacuation SystemTM

Aviation Environmental, Inc. manufactures a containment system designed for use

as an aircraft deicing pad and wash rack. The system consists of a chemical and sun-resistant

polypropylene liner, a foam berm, and an 18-horsepower pump. It can be situated on either 

concrete or asphalt and is attached to the surface using a batten-bar fastening system made from

aluminum. Aircraft enter the containment area by compressing the berm. Collected wastewater is

pumped from the containment area to storage tanks. The system is custom-made to meet

individual customer requirements (5, 40).

6.3.4 Storm Drain Inserts

Storm drain inserts or plugs are used by some airports to close storm drains and

prevent glycol-contaminated wastewater from entering storm water drainage systems. Some

airports, such as Minneapolis-St. Paul International Airport, have designed their own inserts,

while other airports use manufactured inserts. 

One company that manufactures storm drain inserts is AR Plus. This company

manufactures inserts that consist of a steel plate with a gate valve, a mounting bracket with

sealing mastic, and a detachable valve driver. The inserts are mounted directly beneath the storm

drain grate with the steel plate bolted to the mounting bracket. During periods of aircraft

deicing/anti-icing, the valves are closed manually using the detachable valve driver, thereby

preventing ADF-contaminated storm water from entering the storm water drainage system. The

valves can be opened when deicing/anti-icing activities cease, allowing uncontaminated storm

water to pass through the drain. The steel plate containing the valve is removed for maintenance

by removing the bolts that attach the plate to the mounting bracket (41). 

AR Plus manufactures the inserts in standard valve diameters of 6, 8, and 10

inches. The 6-inch valve is the most commonly used. The inserts cost between $1,200 and
Section 6.0 - Pollution Prevention

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$1,800 and have a life expectancy of approximately 7 years. AR Plus also manufacture custommade inserts for drains of unusual shape or size or to meet individual customer specifications. 

Drain inserts are often used in conjunction with glycol vacuum vehicles (discussed

in Section 6.3.5) to collect contaminated storm water. To enable the vacuum trucks to efficiently

collect fluid retained above the insert, the drain inserts are typically mounted approximately 2

inches below the storm drain grate. Although the inserts may be mounted lower to allow the

storm drains to be used as sumps, AR Plus does not recommend this practice because the valves

are more difficult to inspect and maintain. In addition, residual ADF retained in the drain after

evacuation may be washed into the storm water drainage system when the valve is opened. 

The inserts may also be used in an emergency to prevent fuel and other spills from

entering storm water drainage systems. The sealant used in the inserts was specially selected for

its chemical resistance to both glycol and aviation fuel. 

In response to customer comments, AR Plus is currently developing a new system

that will automate the valves so that an operator could close or open several valves by pushing a

single button. 

6.3.5 Glycol Vacuum Vehicles

Specially designed vacuum vehicles provide an alternative approach to the

collection of wastewater generated by aircraft deicing/anti-icing operations. Vacuum vehicles

offer a number of advantages over traditional collection systems: (1) they are versatile, enabling

wastewater to be collected at gate areas, ramps, aircraft parking aprons, taxiways, and aircraft

holding pads; (2) they are cost-effective, enabling airports to avoid the high capital costs of

installing traditional drainage collection systems or deicing pads; and (3) they can collect spent

aircraft deicing fluid in high concentrations, making glycol recovery/recycling economically

feasible. Critics of vacuum vehicles state that they are slow moving, have insufficient collection

capacity, require regular maintenance by trained personnel, and cause ramp and gate area
Section 6.0 - Pollution Prevention

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congestion. Some airports also believe that the airport-wide use of vacuum vehicles is impractical

and prohibitively expensive for airports with high traffic volumes because a large number of units 

would be necessary to efficiently collect the wastewater generated. 

Vacuum vehicles are typically used in conjunction with storm drain inserts or

valves that prevent ADF-contaminated storm water from entering storm water drainage collection

systems. The contaminated storm water ponds around the closed drain grates or surface

depressions and vacuum vehicles collect the ponded fluid. Aircraft parking ramps and gate areas

must be cleared of snow prior to vacuum vehicle use, since collecting large quantities of clean

snow along with contaminated storm water significantly lowers the efficiency of vacuum vehicles.

Several U.S. airports currently use vacuum vehicles, including Minneapolis-St.

Paul International Airport, Baltimore Washington International Airport, Indianapolis International

Airport, Bradley International Airport, Portland International Airport, Washington Dulles

International Airport, Ronald Reagan Washington National Airport, and General Mitchell

International Airport. The U.S. Air Force has also experimented with glycol vacuum vehicles and

currently uses them at several bases. During deicing operations most military aircraft must be

deiced prior to starting their engines; therefore, military aircraft are typically deiced where they

are parked. For the military, glycol vacuum vehicles represent a low-cost collection alternative to

the installation of expensive underground drainage collection systems for large aircraft parking

ramps (5, 42). 

Suppliers of specialized glycol vacuum vehicles for the collection of aircraft

deicing fluids include Vactor Manufacturing, Tennant, Tymco, and VQuip/AR Plus. Products

manufactured by these companies are discussed in detail below. 

Vactor Manufacturing

Vactor Manufacturing of Streator, Illinois, has developed a vacuum truck specially

designed for glycol collection called the Glycol Recovery Vehicle (GRVTM). The GRVTM consists
Section 6.0 - Pollution Prevention

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of a front-mounted spray bar and a rear-mounted vacuum pick-up nozzle. A preheated

emulsifying agent is applied to pavement surfaces using the spray bar. The emulsifying agent

helps to break the cohesion between the deicing fluid and the pavement. The fluid is then

vacuumed from the pavement surface by the 8-foot-wide vacuum pick-up nozzle. Once inside the

collection chamber, changes in air pressure and differences in density cause the deicing fluid

droplets and other debris to fall to the bottom of the chamber. The air stream is passed through a

cyclonic separator to remove any fine droplets remaining in the air stream before it is released to

the atmosphere (3). GRVsTM cost approximately $262,000. 

Three GRVsTM are currently used at Minneapolis-St. Paul International Airport,

primarily to collect wastewater from aircraft deicing operations performed at remote locations on

the airfield. The GRVsTM are owned by the glycol recycler Inland Technologies, Ltd, but are

leased, operated, and maintained by Northwest Airlines. Other airports using GRVsTM include

Cincinnati-Northern Kentucky International Airport, Baltimore Washington International Airport,

Milwaukee’s General Mitchell International Airport, Toronto’s L.B. Pearson International

Airport, Washington Dulles International Airport, Portland International Airport, Detroit

International Airport, Des Moines International Airport, and Ronald Reagan Washington National

Airport (beginning winter 1999).

Tennant

Tennant, based in Minneapolis, Minnesota, manufactures pavement scrubbers and

street sweepers. The company currently offers two models that are specially adapted for

collecting ADF-contaminated wastewater from aircraft deicing operations. Both models are

similar in design; however, the smaller model has a collection capacity of 120 gallons, while the

larger model has a collection capacity of 510 gallons. Dual high-speed brushes scrub off stains,

spills, and dirt, while picking up other debris at the same time. The debris hopper is made of

heavy-duty stainless steel. The optional Solution Recovery System on each model allows the

operator to scrub for longer periods of time. An optional squeegee attachment is also available

for picking up spills. Both units have a cleaning path width of 50 inches. The smaller model
Section 6.0 - Pollution Prevention

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costs approximately $57,000, depending on the specifications of the unit, while the larger model

costs approximately $89,000. These scrubbers are also used to collect debris and spills during the

nondeicing season (43). 

Tennant’s scrubbers are effective in small- to medium-sized airports. Both Niagara

Falls Air Reserve Station in New York and the Groton-New London Airport in Connecticut

currently use Tennant scrubbers (5). The Connecticut Department of Transportation first used

Tennant scrubbers at Bradley International Airport but found their limited capacity was better

suited to the smaller Groton-New London Airport.

Tymco, Inc.

Tymco, based in Waco, Texas, manufactures regenerative air street sweepers that

use a high-velocity air jet to blast debris from pavement surfaces. The air is then drawn into a

hopper where the air stream loses velocity and the heavier pieces of debris are collected. The top

of the hopper is fitted with a screen to prevent light-weight materials, such as paper, from

escaping from the hopper. The air stream then enters a centrifugal dust separator before being

returned to the compressor. The centrifugal separator removes small particles from the air stream

(44). 

Tymco manufactures its sweepers in a variety of sizes, the smallest being Model

210, which is designed for use in parking lots. Tymco’s largest and most powerful sweeper is

Model 600, which is used by airports and the U.S. Air Force to collect debris on runways, aprons,

and ramps. Tymco also sells a modified version of this sweeper, equipped with the company’s

Liquid Recovery System (LRS). The LRS system enables the sweeper to collect fluids from

pavement surfaces, including wastewater from aircraft deicing operations. The modified sweeper

has a 700-gallon storage capacity and costs approximately $75,000. Tymco also sells retrofit kits

that allow existing models to be equipped with an LRS. The kit costs approximately $8,500. 

Tymco sweepers equipped with the LRS have been used at Indianapolis International Airport and

at the Niagara Falls Air Reserve Station in New York. Personnel at Indianapolis International
Section 6.0 - Pollution Prevention

6-41

Airport have reportedly expressed dissatisfaction with the efficiency of the LRS-equipped

sweeper, which in their opinion tends to leave a large amount of residual fluid on pavement

surfaces. In contrast, personnel at the Niagara Falls Air Reserve Station are reportedly pleased

with the performance of their LRS-modified sweepers (5, 44).

AR Plus and VQuip

In the early 1990s, VQuip, in association with AR Plus, developed a vacuum truck

specially designed to collect glycol-contaminated wastewater from aircraft deicing/anti-icing

activities. A prototype unit was tested at Toronto’s L.B. Pearson International Airport in 1992

(45). Unfortunately, this prototype tended to leave behind a residue and had difficulty picking up

Type II fluids because of their thickening agents. Based on this experience, VQuip added a higher

volume vacuum fan and a spray boom designed to remove residual fluid from pavement surfaces

(1).

Today, AR Plus markets two types of VQuip vacuum units: the truck-mounted

Ramp RangerTM and larger trailer-mounted units. Both types are currently in use at Bradley

International Airport in Hartford, Connecticut. The truck-mounted Ramp RangerTM uses a highpressure water spray, rotating brooms, and a rear-mounted, 8-foot, vacuum nozzle with squeegee

to collect contaminated wastewater and other debris. Wastewater is collected in a 875-gallon

storage tank mounted on the rear of the truck. Debris is swept into a hopper that has a capacity

of 5 cubic yards of material. The Ramp RangerTM travels at between 2 and 3 miles per hour and

has a cleaning width of 120 inches. By using the high-pressure water spray, the Ramp RangersTM

can clean residual ADF from airfield pavements. Tests conducted by VQuip showed that the first

pass of the Ramp RangerTM reduced residual glycol on pavement surfaces to less than 100 mg/L

(46). 

The trailer-mounted units are towed by closed-cab tractors. These units do not

have brooms or a debris hopper, but have a large-capacity collection tank. The original trailermounted Ramp RangersTM were equipped with an 1,800-gallon wastewater storage tank. The
Section 6.0 - Pollution Prevention

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Ramp RangerTM costs approximately $250,000. AR Plus also rents the units to airports and

airlines for approximately $100 to $110 per hour of operation (47).

 

In response to customer comments, AR Plus and VQuip developed a new highcapacity vacuum unit with a 1,000-gallon-per-minute collection rate and a larger storage tank. 

The new unit is similar to the trailer-mounted unit described above, but has a 4,000-gallon

wastewater storage tank and two self-priming hydraulic pumps located in front of a 12.5-foot

vacuum nozzle. To remove residual ADF from pavement surfaces, the new unit is equipped with

three independent rotary jets supplied with water from a storage tank mounted on the rear of the

tractor. The new unit operates at 2 to 3 miles per hour when water blasting and 5 miles per hour

when collecting fluid. 

In addition to ADF, the Ramp RangerTM collects slush and debris from airfield

pavements. In previous models, collected slush tended to form a separate layer in the storage

tank. To help mix the tank contents and hasten melting of the slush, the new model is equipped

with a built-in 100-gallon-per-minute recirculation pump. Debris from airfield pavements is

collected in the wastewater storage tank rather than in a separate debris collection hopper. The

storage tank is equipped with a discharge pump specially designed for handling fluids containing

solids. A rotating blade mounted in front of the pump intake protects the pump from any large

pieces of debris. 

AR Plus and VQuip successfully completed field trials using a prototype of the

high-capacity vacuum unit during the 1998-1999 winter season and began marketing the new

model in June 1999. The unit price is approximately $250,000.

6.3.6 Mobile Pumping Station with Fluid Concentration Sensor

AR Plus and VQuip have developed a trailer-mounted, computer-controlled

pumping unit capable of measuring the glycol concentration of the wastewater and diverting it,

based on glycol content, to one of three designated storage tanks. The unit, called the
Section 6.0 - Pollution Prevention

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InterceptorTM, is currently in use at Bradley International Airport in Connecticut and Washington

Dulles International Airport in Virginia. The InterceptorTM is particularly useful for airports

engaging in glycol recovery/recycling programs. 

The InterceptorTM consists of a diesel engine, two pumps, a microprocessor, two

refractometers, two temperature probes, three flow meters, and three fluid discharge ports with

automated valves. The wastewater enters the unit through two flexible hoses attached to ports at

the rear of the unit. The hoses are connected to two submersible, self-priming, hydraulic pumps. 

The pumps may be used to pump ADF-contaminated wastewater from sumps, tanks, or dammed

storm water drainage pipes. Each pump has a capacity of 400 gallons per minute and can be

operated independently (47). 

After entering the unit, the wastewater passes through a refractometer and

temperature probe. The refractometer measurements are used to calculate the glycol

concentration of the wastewater. Measurements are made once per second and recorded by the

microprocessor. Wastewater temperature is measured continuously by the temperature probe,

recorded by the microprocessor, and used for making temperature compensations in calculations

of glycol concentration. The microprocessor analyzes the data once every 15 seconds and opens

and closes valves to the discharge ports based on the glycol concentration. The unit has three

discharge ports, two of which have diameters of 4 inches, while the third has a diameter of 3

inches. The 4-inch discharge ports are used for discharging wastewater with low and medium

glycol concentrations. The 3-inch discharge port is used for discharging wastewater with high

glycol concentration (typically greater than 15 percent). The glycol concentration ranges for the

discharge ports are set by the manufacturer, but can be adjusted to meet customer requirements. 

Flow meters are used to measure the volume of wastewater discharged through each port. 

The InterceptorTM is designed to be operated with minimum operator supervision

and has a self-diagnosis system for identifying problems. When problems are encountered, the 

unit automatically closes all discharge ports, shuts off the unit, and activates a flashing blue

beacon located on the top of the unit. 
Section 6.0 - Pollution Prevention

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The InterceptorTM can be used for ethylene glycol- or propylene glycolcontaminated wastewater and can measure glycol concentrations between 10,000 ppm and

500,000 ppm with an accuracy of 10,000 ppm. AR Plus and VQuip hope to improve the

refractometer so that glycol concentrations of 500 ppm can be detected. 

6.3.7 Containment and Collection Practices for Snow Contaminated with Aircraft

Deicing/Anti-icing Fluids

U.S. airports that experience heavy snowfalls typically collect snow from aircraft

parking ramps and aprons, and transport it to designated collection areas referred to as snow

dumps. Because most aircraft deicing/anti-icing operations are conducted at passenger terminals

and aircraft parking ramps, snow collected from these locations may be contaminated with ADF,

as well as small amounts of pavement deicing/anti-icing agents. Consequently, snow dumps that

are used for disposal of contaminated snow should include provisions for collecting or containing

the contaminated melt water. At Albany International Airport, for example, two concrete pads,

each with its own drainage collection system, are used to store snow contaminated with

deicing/anti-icing chemicals. As the snow melts, the melt water flows into the drains and is

conveyed to the airport’s wastewater storage units (32). A similar system is currently under

construction at Buffalo-Niagara International Airport (7). EPA believes that collection of melt

water at snow dumps used for ADF-contaminated snow has not yet become common practice. 

An alternative approach taken by several North American airports is the use of

specially designed, high-performance snow melters. The units may be stationary or portable, and

typically consist of a tank which is equipped with a heating system and filled with water. Snow is

dumped into the tank using a front-end loader. At Chicago O’Hare International Airport, for

example, portable snow melters are strategically positioned at the passenger terminals and cargo

aprons so that the snow melt generated drains to the airport’s storm water collection system. The

snow melters are manufactured by Aero Snow and are powered by jet fuel. Each unit is capable

of melting 600 tons of snow per hour. The snow melters cost approximately $14 million each,

but can be leased for $6,000 per hour per unit. 
Section 6.0 - Pollution Prevention

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A similar system is used at Toronto’s L.B. Pearson International Airport, where

snow melters manufactured by Trecan Combustion Limited are used to melt ADF-contaminated

snow collected from the passenger terminals. Discharge from the snow melters is collected in

underground storage tanks (also used for storing wastewater from aircraft deicing/anti-icing

operations) and discharged to a local POTW (5, 48). The principal disadvantages associated with

snow melters are the air emissions and the operating costs.

6.4 Glycol Recycling

Due to the high biochemical oxygen demand exerted by glycol-based ADFs, many

POTWs either refuse to accept ADF-contaminated wastewater from airports or charge high fees

for its treatment. To alleviate this problem and meet NPDES permit requirements, several U.S.

airports now recover glycol from ADF-contaminated wastewater. Although a variety of on-site

treatment systems are available (see Section 7.2), glycol recycling offers airports the additional

benefit of offsetting some of their treatment costs by generating revenue from the sale of the

recovered glycol. 

Recycling systems rely on a series of standard separation techniques to remove

water and suspended solids and, in some cases, surfactants, corrosion inhibitors, and other

additives from ADF-contaminated wastewater. The typical glycol recycling system is operated as

a batch process due to the variation in influent composition. The glycol recycling process

generally consists of several steps, which may include filtration, ion exchange, nanofiltration,

flocculation, reverse osmosis, evaporation, and distillation. Filtration is the first step in all glycol

recycling systems because it removes suspended solids and prevents plugging of subsequent

processing units. Once filtered, the wastewater may be passed through a series of ion-exchange

columns to remove dissolved solids such as chlorides and sulfates. Nanofiltration and/or

flocculation may be used to remove polymer-based additives, such as thickening agents, corrosion

inhibitors, and surfactants. Water may be removed using distillation, evaporation, or reverse

osmosis. Recycling systems that use distillation to remove water can produce products with

glycol concentrations as high as 98 percent. However, because distillation is an energy-intensive
Section 6.0 - Pollution Prevention

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separation method, distillation-based recycling systems have relatively high annual operating costs

(49). Consequently, several recycling companies have developed less energy-intensive recycling

systems that remove water using evaporation, vapor recompression, or reverse osmosis. Typical

products from evaporation-based systems contain between 50 and 60% glycol, whereas those

from reverse osmosis-based systems contain only about 10% glycol. 

Glycol recovery systems also generate process wastewater containing small

amounts of glycol and, in some cases, ADF additives. All glycol recovery systems currently in

operation in the U.S. discharge their process wastewater to a POTW via a storage tank or

detention pond.

Although most recycling systems can successfully recover glycol from ADFcontaminated storm water with glycol concentrations as low as 2.5% (50), airports involved in

glycol recycling strive to collect wastewater with the highest possible glycol concentration. ADFcontaminated wastewater with low glycol concentration is segregated from that with high glycol

concentration and stored in tanks or ponds. Ponds are sometimes equipped with covers to reduce

glycol degradation by sunlight. In situations where the glycol concentration of the collected

wastewater is very low, preconcentration techniques, such as reverse osmosis, can be used to

increase the glycol concentration. Preconcentration methods, however, must be followed by

additional steps and generally have higher capital and operating costs. In addition, reverse

osmosis systems are easily fouled and may require considerable maintenance (20). 

The first U.S. airport to experiment with glycol recycling was Stapleton Airport in

Denver, Colorado. Prior to Stapleton’s closure in 1995, Continental Airlines operated an aircraft

deicing pad where storm water runoff consistently contained glycol concentrations of more than

20 percent. The runoff from this pad was collected and the glycol recovered for profit, thereby

demonstrating the financial feasibility of glycol recycling from aircraft deicing/anti-icing

operations. Since that time, interest in glycol recovery has increased, and today on-site recycling

of ADF-contaminated wastewater is successfully performed at several U.S. airports, including

Denver International Airport, Bradley International Airport, and Minneapolis-St. Paul
Section 6.0 - Pollution Prevention

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International Airport. Some U.S. airports collect a portion of their wastewater from aircraft

deicing/anti-icing operations for off-site glycol recycling, including Newark International Airport,

Des Moines International Airport, Cleveland Hopkins International Airport, Pittsburgh

International Airport, Detroit Wayne County Metropolitan, and Albany International Airport. 

Salt Lake City International Airport and Washington Dulles International Airport will begin onsite recycling during the 1999-2000 deicing season, while T.F. Green State Airport in Providence,

Rhode Island, and General Mitchell International Airport in Milwaukee, Wisconsin, are planning

pilot recycling programs for the 1999-2000 deicing season. Buffalo Niagara International Airport

in Buffalo, New York, plans to begin an ADF recycling program during the 2000-2001 deicing

season. 

6.4.1 Glycol Recyclers

There are currently five principal companies providing glycol recycling services for

airports and airlines. These include Aircraft Deicing Services, Inc., The Environmental Quality

Company, Inland Technologies, Ltd., AR Plus, and Deicing Systems AB. Each company’s

recycling system is discussed in detail below.

Aircraft Deicing Services, Inc.

Aircraft Deicing Services, Inc. (ADSI) designed and constructed the on-site glycol

recycling facility currently in operation at Denver International Airport. The ADSI recycling

system uses distillation to remove water from the fluid, but cannot separate mixtures of ethylene

glycol and propylene glycol. Consequently, the airport allows airlines to use only propylene

glycol-based ADFs. 

Denver International Airport collects ADF-contaminated storm water with high

glycol concentrations (up to 25%) from aircraft deicing pads. The contaminated wastewater is

stored in detention ponds and tanks prior to treatment at the on-site glycol recycling facility. The

fluid is preheated using a heat exchanger prior to entering an 8,000-gallon flocculation tank. The
Section 6.0 - Pollution Prevention

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fluid is treated with chemicals designed to speed the flocculation of surfactants, wetting agents,

corrosion inhibitors, and thickening agents. The flocculation tank is cleaned annually and only

trace amounts of residual solids accumulate in the tank. After flocculation, the fluid passes

through two additional heat exchangers before entering a series of three packed vacuum

distillation towers. Vapor from the distillation towers is condensed in an air-cooled chiller. The

condensate, which typically contains about 15 to 40 ppm glycol, is discharged to a holding pond

prior to discharge to a POTW. The product, which typically contains approximately 98%

propylene glycol, is sold to various secondary markets. The glycol concentration of the product

can be varied to meet customer needs. The profits from the sale of the recovered propylene

glycol are shared between the City of Denver (who owns and operates the airport) and ADSI.

 The facility can process wastewater at a rate of between 7 to 24.5 gpm for

influent glycol concentrations above 10 percent. Although wastewater with glycol concentrations

above 10% is preferable, this system is capable of treating wastewater with glycol concentrations

as low as 2.5 percent. ADSI is also considering investing in additional equipment that would

allow treatment of storm water with glycol concentrations as low as 20 ppm. The facility is

capable of processing 12 to 15 million gallons of wastewater each year, and recovered 245,000

gallons of recovered propylene glycol during the 1997/1998 deicing season (50). 

The Environmental Quality Company

The Environmental Quality Company (EQ) is an environmental management

company based in Wayne, Michigan, that assists airports in managing wastewater from aircraft

deicing operations. The company currently recycles wastewater collected at Pittsburgh

International Airport and the Detroit Wayne County Metropolitan Airport. Wastewater collected

at these airports is trucked to Michigan Recovery Systems, Inc., a subsidiary of EQ based in

Romulus, Michigan. The plant can produce a 99% pure glycol product, but cannot separate

mixtures of propylene glycol and ethylene glycol. The recycling system is operated as a batch

process and can process wastewater with glycol concentrations as low as 1 percent. The water is

removed using a high-efficiency evaporator followed by distillation. The product is treated with a
Section 6.0 - Pollution Prevention

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proprietary polishing process prior to sale. Process wastewater is discharged to a POTW, while

solid wastes are disposed of off site as a RCRA nonhazardous waste. The facility processes

approximately 5 million gallons of wastewater per year (51). 

EQ has also developed a glycol recycling system capable of separating mixtures of

ethylene glycol and propylene glycol. In 1997, the company was approached by Salt Lake City

Airport Authority to design, construct, and operate a glycol recycling facility at Salt Lake City

International Airport. The recycling system was constructed in 1998-1999 and is scheduled to 

begin operating in January 2000. 

The recycling system installed at Salt Lake City International Airport is a two-step

process. In the first step, a high-efficiency evaporator will concentrate the glycol to a

concentration of approximately 80 percent. In the second step, vacuum distillation will remove

additional water and separate ethylene glycol from propylene glycol. The glycol concentration of

the influent will be approximately 2%, while the purity of the recovered glycol will be

approximately 99 percent. The plant is designed to handle 72,000 gallons of wastewater per day

and is expected, based on fluid usage logs and anticipated wastewater capture rates, to operate for

about 280 days each year. EQ is responsible for marketing the product, which will be sold to

secondary markets. Process wastewater generated by the plant will be held in storage tanks and

discharged to the local POTW. 

The capital costs for construction of the recycling facility were approximately $4.5

million, of which approximately $1 million was the cost of the distillation column required to

separate ethylene glycol and propylene glycol mixtures. In addition to capital costs, the Airport

Authority also incurs the plant’s annual operating expenses, which are projected to be $760,000. 

The revenues from sale of ethylene glycol and propylene glycol are estimated to be $460,000 per

year, leaving a shortfall of $300,000, which will be covered by an increase in landing fees. The

airport’s tenants were consulted during the planning and decision-making process and agreed to

pay higher landing fees, provided the Airport Authority continued to allow airlines to use both

ethylene glycol- and propylene glycol-based ADFs.
Section 6.0 - Pollution Prevention

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Inland Technologies, Ltd.

Inland Technologies, Ltd. (Inland) is a waste management company based in

Truro, Nova Scotia, specializing in the disposal and treatment of a wide range of liquid and solid

wastes. In 1992, following Environment Canada’s introduction of its 100 mg/L voluntary glycol

guideline (discussed in Section 13.3.1), Inland was approached by a number of Canadian airports

to dispose of glycol-contaminated wastewater generated during aircraft deicing/anti-icing

operations. After considering the available disposal options and evaluating the secondary

markets, Inland concluded that glycol recycling could provide a cost-effective means by which

Canadian airports could meet the new guideline. 

The recycling system developed by Inland removes water from ADF-contaminated

wastewater using mechanical vapor recompression. The principal components of the system are a

heat exchanger, an evaporation tank, a cyclone, and a steam compressor. The recovery process is

monitored and controlled by computer. To conserve energy and improve efficiency, the influent is

preheated in a heat exchanger using heat from the hot distillate and recovered product. The

influent is then evaporated in the evaporation tank. Following evaporation, the glycol/steam

mixture enters the cyclone where steam is separated from the recovered glycol product. The

steam is then compressed and used as a heat source for the evaporation tank and heat exchanger. 

The recovered glycol passes through the heat exchanger before being further purified by

proprietary polishing filters. The distillate is typically discharged to a POTW, while the recovered

glycol may be sold to secondary markets or reformulated into a Type I fluid (52). 

Inland has designed its recycling system to be self-contained and portable. The

units are mounted on trailers and are capable of processing 264 gallons of wastewater per hour. 

The typical influent contains at least 5% glycol, which may be either ethylene glycol or propylene

glycol. Because the boiling points of ethylene glycol and propylene glycol are very close, the

system cannot separate mixtures of these glycols. The typical recovered product is approximately

a 50% glycol and 50% water solution, although the process can achieve concentrations as high as

60% glycol. The distillate (i.e., process wastewater) typically contains 0.5% glycol (25, 52). 
Section 6.0 - Pollution Prevention

6-51

Inland’s first recycling unit was installed at Montreal’s Dorval International

Airport in Quebec, Canada in 1996. Inland does not currently recover glycol from spent aircraft

deicing fluids collected at Dorval International Airport because the airport is able to inexpensively

dispose of wastewater at a nearby wastewater treatment plant. The facility instead recovers

glycol from spent aircraft deicing fluids collected at several other Canadian airports (MontrealMirabel International Airport, Quebec City Airport, Ottawa International Airport, Thunder Bay

Airport, and Winnipeg International Airport) and trucks it to the Dorval facility for recycling. 

Inland currently operates four skid-mounted processing units at Dorval. 

Inland’s first U.S.-based glycol recycling facility was installed in the spring of 1997

at the Minneapolis-St. Paul International Airport in Minnesota. At this airport, Inland processes

glycol-contaminated storm water from aircraft deicing/anti-icing operations under a contract with

Northwest Airlines. Inland charges Northwest a fixed fee for use of the glycol recycling system,

while Northwest receives a portion of the revenues from the sale of the recovered product. The

fee charged by Inland is based in part on the unit operating costs for the glycol recycling system,

which are approximately $0.10 to $0.20 per gallon of recovered product. For the three years that

the facility has been operational, the sale of the recovered product has always covered the

operating costs. The Minneapolis-St. Paul facility also recovers glycol from spent deicing fluid

collected at Des Moines International Airport in Iowa. Approximately 4,000 to 5,000 gallons of

ADF-contaminated wastewater is trucked from the Des Moines airport to the recycling facility at

the Minneapolis-St. Paul International Airport each winter.

Currently, Inland has glycol recycling facilities at four North American airports

(Dorval International Airport in Montreal, L.B. Pearson International Airport in Toronto,

Minneapolis-St. Paul International Airport in Minnesota, and Washington Dulles International

Airport in Virginia). Inland’s Canadian facilities typically recover ethylene glycol, while its

facilities at Minneapolis-St. Paul International Airport and Washington Dulles International

Airport recover the more profitable propylene glycol. In all cases, Inland personnel operate the

glycol recycling system and market the recovered product. Because the demand for pure,

concentrated glycol product is generally greater than the demand for its 50% glycol solutions,
Section 6.0 - Pollution Prevention

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Inland sells most of its product to Consolidated Recycling based in Troy, Indiana, where it is

concentrated and purified using distillation. Inland has also developed a method for producing a

reformulated Type I fluid by blending their 50% glycol product with additives such as wetting

agents, corrosion inhibitors, and flame retardants. Inland expects to begin marketing its

reformulated Type I fluid in the near future.

AR Plus

AR Plus is an aviation focused environmental firm based in Ontario, Canada that

collects and recycles aircraft deicing fluid for airlines, and provides assistance to airports in

managing wastewater from aircraft deicing operations. AR Plus manages a glycol collection and

recycling process at Bradley International Airport in Windsor Locks, Connecticut, as well as

several other North American locations. 

The recycling system developed by AR Plus uses reverse osmosis to remove water

from ADF-contaminated storm water. The system consists of three processing steps: (1)

flocculation to remove additives and suspended solids; (2) reverse osmosis to remove water; and

(3) microfiltration as a final polishing step. The system installed at Bradley International Airport

is capable of processing 20,000 gallons of wastewater per day and is operated as a batch process. 

The glycol concentration of all wastewater received by the recycling facility is measured using a

digital refractometer. This initial analysis enables AR Plus to segregate wastewater based on

glycol content. Wastewater with glycol concentrations of less than 10% is processed by the

system’s two reverse osmosis units, which increase the glycol concentration to between 8 and 10

percent. The type of membrane used in the reverse osmosis units was selected by AR Plus for its

ability to resist fouling by polymeric additives and other contaminants found in ADF-contaminated

storm water. The membranes are cleaned periodically to enhance operational efficiency.

Concentrate from the reverse osmosis units and collected streams with glycol concentrations

above 10% are processed through a proprietary process, which removes additional contaminants. 

The process wastewater from the reverse osmosis units contains less than 100 ppm glycol and is

discharged to a POTW. 
Section 6.0 - Pollution Prevention

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As part of the sampling program for this study, EPA collected grab samples of the

influent to wastewater treatment, effluent from the first reverse osmosis unit, and the process

wastewater discharged to the POTW. As shown in the following table, the reverse osmosis

treatment system was able to remove most of the pollutants detected in the influent sample,

including tolyltriazole. Data provided by AR Plus show that the glycol concentration in the

effluent discharged to the POTW ranges from <2 mg/L to 120 mg/L, while the chemical oxygen

demand ranges from 30 mg/L to 180 mg/L. The average glycol concentration is approximately 70

mg/L, while the average chemical oxygen demand is approximately 112 mg/L. 

Pollutant to First RO Unit First RO Unit POTW

Influent Effluent from Effluent to

Propylene Glycol (mg/L) 160,000 8,720 62.7

Ethylene Glycol (mg/L) 3,010 27.0 ND(10)

Tolyltriazole (mg/L) 90 5.9 0.13

Phenol (ug/L) 277 45.9 ND(10)

Total Organic Carbon (mg/L) 35,300 1,320 11.3

Ammonia as Nitrogen (mg/L) 22.7 4.7 0.29

Hexane Extractable Material (mg/L) 173 ND(6) ND(5)

ND - Not detected (followed by the detection limit).

Although the AR Plus glycol recycling system can process either propylene glycol

or ethylene glycol, it cannot separate mixtures of these chemicals. Due to the higher value and

greater demand for recovered propylene glycol, AR Plus processes propylene glycol-based ADF

at Bradley International Airport. At other locations, however, AR Plus handles storm water

contaminated with ethylene glycol-based fluids. The recovered glycol may be sold to secondary

markets or reformulated into ADF. AR Plus in association with Octagon Process, Inc. (Octagon),

has developed a method for producing a reformulated Type I fluid by blending their glycol

product with concentrated propylene glycol and additives (e.g., wetting agents, flame retardants,

corrosion inhibitors). AR Plus and Octagon have begun marketing their reformulated fluid to

domestic airlines and FBOs. AR Plus charges Bradley International Airport a fee for processing
Section 6.0 - Pollution Prevention

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wastewater with glycol concentrations less than 10%, but shares the revenue from the sale of the

recovered glycol.

Deicing Systems AB

Deicing Systems AB (DSAB) is a leading European glycol recycler based in

Kiruna, Sweden. The company markets a closed aircraft deicing system in which spent ADF is

collected from aircraft deicing pads, reprocessed into Type I fluid at an on-site plant, and

reapplied to aircraft. DSAB currently operates glycol recycling facilities at the Munich Airport in

Germany, the Oslo Airport in Norway, and the Lulea Airport in Sweden (14). 

The DSAB system was designed to collect wastewater from aircraft deicing and

anti-icing operations with the highest possible glycol concentration by minimizing dilution from

precipitation. The system installed at the Munich Airport, for example, collects runoff with an

average glycol concentration of 18.6 percent. Once collected, the fluid is passed through filters

and cationic and anionic ion exchange columns to remove suspended solids and dissolved salts,

respectively. The fluid is then preheated by heat exchangers before entering the facility’s two

distillation towers. The distillation towers are operated in series, with the resulting process

wastewater containing less than 1.5% (15,000 ppm) glycol. The glycol concentration of the

product is monitored using a densitometer and typically contains approximately 55% glycol. The

product is reformulated on site into a Type I fluid by adding additives such as wetting agents and

corrosion inhibitors. The recycling process is controlled and monitored by computer, and DSAB

conducts an extensive quality control program to ensure that the reformulated fluids meet the

European standards for Type I fluids established by the International Organization for

Standardization (i.e., ISO 11075, Aircraft Deicing/Anti-icing Newtonian Fluids ISO Type I) (5,

14). One disadvantage of DSAB’s recycling/reformulation process is that it can successfully

recycle only Type I fluids. DSAB reportedly experienced problems processing anti-icing fluids,

whose polymer-based thickening agents tend to clog filters (5, 14). 
Section 6.0 - Pollution Prevention

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DSAB’s largest recycling/reformulation facility is located at the Munich Airport

and can process 1,320 gallons/hour. The systems installed at the Lulea and Oslo airports are

smaller than the Munich system and have capacities of 80 gallons/hour and 530 gallons/hour,

respectively. Currently, no North American application of the DSAB recycling/reformulation

system is known (49).

6.4.2 Current Uses for Recovered Glycol

Most glycol recovered from aircraft deicing/anti-icing operations is sold to

chemical manufacturers for use in other glycol-based products. Recovered propylene glycol is

used in several industries, including coatings, paints, and plastics. Recovered ethylene glycol is

used primarily as anti-freeze in the automobile and coal industries and as a feedstock in the

manufacture of polyester fibers for the garment industry. At some European airports, recovered

glycol is reused as an aircraft deicing fluid after the addition of wetting agents and corrosion

inhibitors.

In contrast to European practices, recovered glycol is not currently reused for

aircraft deicing/anti-icing in the U.S. or Canada. North American airlines have been reluctant to

use fluids made from recycled ADF due to safety issues and liability concerns. Despite this

reluctance, two Canadian recyclers, Inland and AR Plus, have developed methods that enable

recovered glycol to be reformulated at on-site facilities and reused as Type I fluids.

Before the reformulated fluids can be used on aircraft, recyclers must demonstrate

that their fluids meet the same aerodynamic, corrosion, and performance standards required for

new fluids. These standards are set by The Society for Automotive Engineers (SAE) (see Section

13.5) and, for Type I fluids, can be found in Aerospace Material Specification (AMS) 1424. The

certification process involves independent laboratory testing, which is conducted at the Scientific

Material International (SMI) laboratory in Miami and the Anti-Icing Materials Laboratory

(AMIL) of the University of Quebec in Chicoutimi, Canada. The testing consists of material

comparability tests, aerodynamic performance tests, and stability tests. 
Section 6.0 - Pollution Prevention

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To date, Inland’s reformulated fluid has been independently tested by the AMIL

and SMI laboratories. According to Inland, the results show that the reformulated fluid conforms

to SAE specifications. Inland plans to conduct trials to ensure that their fluid meets SAE fluid

quality standards under field conditions. The company hopes to receive SAE certification for its

recycling/reformulation process, which will allow Inland to sell its reformulated fluid without

having each batch of fluid independently certified (25, 52). 

As mentioned earlier, the AR Plus recycling/reformulation process is a

collaborative effort with Octagon, an ADF formulator. AR Plus processes spent ADF in batches

and sends a sample of each batch of recovered glycol to Octagon for analysis. Based on the

results, Octagon calculates the correct amount of each additive needed to reformulate the fluid to

meet SAE Type I specifications. AR Plus blends the recycled glycol with additives and

concentrated propylene glycol provided by Octagon to produce a reformulated Type I fluid, a

sample of which is sent to Octagon for analysis and certification. The blending process is

conducted at the AR Plus on-site recycling facility at Bradley International Airport. 

 Both Inland and AR Plus expect the reformulation of the recovered glycol into a

Type I fluid to greatly improve the profitability of the recycling process, particularly in Canada

where use of ethylene glycol-based ADF predominates. 

6.4.3 Operational and Economic Issues

Several factors affect the profitability of glycol recycling, including: (1) volume of

fluid used; (2) glycol concentration of collected wastewater; (3) frequency of wastewater

generation; (4) transportation costs for the wastewater and/or recovered glycol; (5) processing

costs; and (6) commercial value of the recovered product. For the recycling process to be

profitable, the revenues generated from the sale of the recovered glycol must equal or exceed the

costs of collection and recovery. However, because glycol recycling reduces the amount and

strength of wastewater, which reduces wastewater disposal costs, recycling may represent a costeffective method of disposal even when the revenues from the sale of recovered glycol do not
Section 6.0 - Pollution Prevention

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offset the costs of collection and recovery. For example, airports with very high POTW discharge

costs may benefit from reduced BOD and hydraulic loading surcharges.

One of the most important factors affecting the cost-effectiveness of glycol

recycling is the amount of glycol in the wastewater. In general, the higher the glycol

concentration of the wastewater, the easier and more cost-effective it is to process. The

concentration of glycol in aircraft deicing/anti-icing runoff varies widely and is dependent on the

method of collection and prevailing weather conditions. Currently, airports collect wastewater

with 5% to 20% glycol concentrations using glycol vacuum vehicles (described in Section 6.3.5), 

storm drain inserts (described in Section 6.3.4), and/or aircraft deicing pads with drainage

collection systems (described in Section 6.3.1). In the early 1990s, wastewater with glycol

concentrations above 15% were thought necessary to make glycol recycling economically viable

(49). Over the last two to three years, ADF recyclers have improved their processing capabilities,

so that today wastewater with glycol concentrations of greater than 5% are generally considered

economically feasible to recycle (20).

The value of the recovered glycol depends on the type of glycol and its

concentration and purity. The market demand for ethylene glycol is generally lower and more

volatile than the demand for propylene glycol. A 50% solution of propylene glycol sells for

between $0.75 and $1.10 per gallon, while a 50% solution of ethylene glycol sells for between

$0.38 and $0.68 per gallon. This difference is most likely because the range of industrial uses for

ethylene glycol is narrower than that for propylene glycol. Consequently, most recyclers prefer to

process propylene glycol-based ADF. 

Although 50% glycol solutions can be sold for use as antifreeze in the automotive

industry, most other industries require concentrated glycol feedstocks with high purity. As a

result, the concentrated product produced by distillation-based recycling systems has a higher

value than the 50% glycol solutions produced by reverse osmosis, vapor recompression, and

evaporation-based systems. A highly purified propylene glycol product currently sells for between

$2.00 and $2.50 per gallon. 
Section 6.0 - Pollution Prevention

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As mentioned previously, mixtures of ethylene glycol and propylene glycol are

difficult and expensive to separate due to the similarity of their boiling points. Recovered product

that contains a mixture of propylene glycol and ethylene glycol may be difficult to sell. Mixtures

of glycols are typically sold for the same price as recovered ethylene glycol products, even when

the percentage of ethylene glycol is low. As a result, most airports and airlines currently recycling

ADF either allow only one type of fluid to be used (Denver International Airport and Bradley

International Airport) or segregate the waste streams (Minneapolis-St. Paul International

Airport). The only exception is Salt Lake City International Airport, where the on-site recycling

facility was designed to separate mixtures of ethylene glycol and propylene glycol. 

In the past, glycol recycling was considered applicable only for major airports

where large volumes of aircraft deicing and anti-icing fluids are sprayed throughout the winter

season and which had the capital to invest in large on-site distillation-based systems. Recent

developments have shown that on-site recycling can be successful at smaller airports, such as

Bradley International Airport. In addition, some small airports have been be able to transport

their wastewater to nearby recycling facilities, often with the transportation costs paid for by the

recycler. As a result, several U.S. airports are reported to be considering incorporating glycol

recycling into their wastewater management plans, including Ronald Reagan Washington National

Airport, Dallas-Ft. Worth International Airport, Buffalo Niagara International Airport, and

Dayton International Airport. Nevertheless, glycol recycling may not be feasible at all U.S.

airports. The volume of fluid used at very small commercial airports and U.S. Air Force bases,

for example, may still be insufficient to make recycling economically viable for these facilities

(42). Glycol recycling may also be uneconomical for airports located far from secondary glycol

markets (e.g., Anchorage International Airport); however, recent developments in the

reformulation of recovered product into Type I fluids may make on-site reuse possible. 
Section 6.0 - Pollution Prevention

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6.5 Pollution Prevention Practices for Airfield Pavement Deicing/Anti-icing

Operations

This section discusses the pollution prevention practices currently in use or under

development for airfield pavement deicing/anti-icing operations. These practices include: (1) use

of alternative pavement deicing/anti-icing agents; (2) implementation of alternative pavement

deicing/anti-icing methods; and (3) adoption of pavement deicing/anti-icing agent minimization

practices.

6.5.1 Alternative Airfield Pavement Deicing/Anti-icing Agents

Historically, urea, ethylene glycol, or a combination of the two were the pavement

deicing/anti-icing agents most commonly used by U.S. airports for deicing/anti-icing airfield

pavements. Propylene glycol was approved by the FAA for runway deicing/anti-icing in October

1990. Although these chemicals are very effective deicing/anti-icing agents, they have long been

recognized as having an impact on the environment. This concern led to the development of

several alternative pavement deicing/anti-icing products that have low aquatic and mammalian

toxicities, biodegrade readily in the environment, and exert lower biochemical oxygen demand

than glycol-based products. New products include solid and liquid pavement deicers/anti-icers

that contain potassium acetate, sodium acetate, sodium formate, potassium formate, or calcium

magnesium acetate (CMA) as the freezing point depressant. The solid pavement deicers/anti-icers

are applied using the same mechanical spreaders used for urea, while the liquid deicers/anti-icers

are applied using the same spray booms used for glycol-based products.

U.S. airports were initially apprehensive about replacing traditional pavement

deicers/anti-icers with the new products because of higher purchase costs and concern that some

of these products may contribute to the corrosion of airfield electrical systems (e.g., runway

lights). An industry workgroup is currently investigating this issue. Today, many U.S. airports

have phased out urea and glycol-based products, most replacing them with potassium acetatebased deicers/anti-icers. The U.S. Air Force, which banned the use of ethylene glycol-based
Section 6.0 - Pollution Prevention

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aircraft and pavement deicing/anti-icing products in 1992, now uses potassium acetate, sodium

acetate, and sodium formate on runways and taxiways at its bases. Although urea is still widely

used both by commercial airports and the U.S. Air Force, several major U.S. airports have

recently discontinued its use, including Dayton International Airport, Minneapolis-St. Paul

International Airport, Bradley International Airport, Newark International Airport, and Duluth

International Airport.

6.5.2 Alternative Airfield Pavement Deicing/Anti-icing Methods

One method for eliminating pavement deicing and anti-icing chemicals is heating

the pavement to maintain its temperature above the freezing point of water, thereby preventing ice

formation. In addition to the environmental benefits associated with eliminating discharges of

potentially harmful chemicals to the environment, heated pavement systems have the potential to

improve passenger safety. 

The leading manufacturer of heated pavement systems is Superior Graphite

Company, a Chicago-based manufacturer of graphite and carbon products. In the early 1990s,

this company developed the SNOWFREETM Heated Pavement System, which uses an electrical

current as the heat source. The system includes a base layer consisting of copper cables, installed

perpendicular to the runway surface, embedded in a 2-inch thick conductive material composed of

a mixture of synthetic graphite and asphalt. The pavement surface consists of a 2-inch layer of

asphalt. Electricity passing through the conductive layer generates enough heat to maintain the

temperature of the pavement surface slightly above freezing, preventing ice from forming and

melting any snow that may accumulate. The system may be used on runways, taxiways, highway

bridges, and ramps. 

Superior Graphite Company believes the system will be effective at aircraft

touchdown points and high-speed turnoffs. The system was tested at the Chicago O’Hare

International Airport during the 1994 and 1995 winter seasons, where a prototype was installed

on one of the airport’s taxiways. The system reportedly performed well with little maintenance
Section 6.0 - Pollution Prevention

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required, but was expensive to operate. The cost to heat a 10,000-foot runway is estimated at

approximately $3,000 per hour. Installation costs are approximately $15 per square foot. 

Although the system is expensive to operate, the company believes that these costs are largely

offset by savings in deicing/anti-icing chemicals, application equipment, and labor costs. The New

Jersey Department of Transportation plans additional tests of the system during the 1999/2000

winter, with an evaluation report published the following summer. No commercial application of

the SNOWFREETM system is currently known (5, 53). 

A similar heated pavement system is reportedly being developed by Thermacore,

Inc., based in Lancaster, Pennsylvania. The Thermacore system would use heated pipes to

maintain the pavement temperature above the freezing point of water. The heating system would

be activated automatically by pavement temperature sensors (discussed in Section 6.5.3) installed

on the runway. The current status of this project is unknown (54).

Thermal Power Corporation, based in Almont, Michigan, manufactures a truckmounted pavement heating system called the Heat MasterTM. The system was initially developed

for preheating asphalt pavements for repair work, and consists of a heating panel capable of

emitting 120,000 BTUs. The Heat MasterTM was tested in 1994 on a runway at a general aviation

airport located near Pontiac, Michigan. The test results reportedly show that the unit can melt ice

layers as thick as 1.5 inches without damaging the runway surface, painted lines, or in-pavement

lights. EPA currently knows of no commercial application of the Heat Master at a U.S. airport

(5). 

6.5.3 Airfield Pavement Deicing/Anti-icing Minimization Practices

Applying deicing/anti-icing agents in conditions where ice and snow adheres to

pavement surfaces is extremely important for the safe operation of aircraft and ultimately for

passenger safety. Unnecessary or over-application of pavement deicing/anti-icing agents,

however, is not only harmful to the environment but also wasteful of airport resources. This

section describes the methods used by U.S. airports to minimize the amount of agents applied to
Section 6.0 - Pollution Prevention

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airfield pavements, including: (1) adopting good winter maintenance practices; (2) using

preventative anti-icing when icing conditions are forecast; and (3) using runway surface

monitoring systems to provide detailed information about runway conditions. 

6.5.3.1 Good Winter Maintenance Practices

Airport managers that follow good winter maintenance practices can prevent

unnecessary or over-application of pavement deicing/anti-icing chemicals. Good winter

maintenance practices for airports are outlined in the FAA Advisory Circular, AC 150/5200-30A,

Airport Winter Safety and Operations (31). These practices include:

C Prompt treating of airfield pavements using either mechanical methods (i.e.,

sweepers, displacement plows, rotary plows) or anti-icing chemicals to

prevent strong bonds from forming between the frozen precipitation and

the pavement surface;

C Using mechanical methods to remove dry snow from airfield pavements,

rather than applying deicing/anti-icing chemicals; 

C Applying pavement anti-icing chemicals prior to a storm event or icing

conditions, when weather forecasts indicate that ice or snow will bond to

pavement surfaces; 

C Applying pavement deicing/anti-icing chemicals at rates recommended by

the manufacturer;

C Frequently recalibrating chemical and abrasive spreading equipment to

ensure an optimal application rate;

C Monitoring weather conditions and obtaining accurate weather forecasts

from the National Weather Service or a private contractor;

C Preventing snow from drifting across runways and taxiways by installing

snow fences or constructing snow trenches;

C Avoiding heavy applications of sand, which can insulate ice and snow from

solar radiation and deicing chemicals;

 
Section 6.0 - Pollution Prevention

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C Storing solid pavement deicing/anti-icing chemicals in enclosed buildings to

prevent product degradation and leaching by storm water; and

C Wetting solid deicing/anti-icing chemicals prior to application to increase

their effectiveness and reduce the potential for light-weight particles to be

blown off the pavement by strong winds and/or jet blast.

These practices also improve airport safety and minimize delays for airport tenants.

6.5.3.2 Preventive Anti-Icing

By applying pavement anti-icing chemicals, such as aqueous potassium acetate, 

prior to the onset of freezing conditions or a storm event, airport managers can prevent strong

bonds from forming between the pavement surface and ice molecules, enabling snow and ice

accumulations to be removed easily using sweepers and plows. The FAA estimates that the

correct application of pavement anti-icing chemicals can reduce the overall quantity of pavement

deicing and anti-icing agents used at an airport by between 30 and 75 percent (55). 

Correctly timing the application of anti-icing chemicals is extremely important. To

be effective, anti-icing chemicals should be applied to a clean pavement while the pavement

surface temperature is still above freezing. Accurate weather forecasts, combined with pavement

surface temperature data, are essential for airport managers to correctly time the application of

pavement anti-icing chemicals. Advanced weather forecast systems, such as the Weather Support

to Deicing Decision Making system (discussed in Section 6.2.2) and runway surface condition

monitoring systems (discussed in Section 6.5.3.3) are particularly useful tools for assisting airport

managers with these decisions. 

6.5.3.3 Runway Surface Condition Monitoring Systems

One of the best means of preventing unnecessary application of pavement

deicing/anti-icing agents is using runway surface condition monitoring systems. These devices

measure the pavement temperature and detect surface contamination, such as water, ice, snow,
Section 6.0 - Pollution Prevention

6-64

and residual deicing/anti-icing chemicals. The typical system consists of several remote sensors

embedded in the runway pavement that collect and transmit data to a control center where the

data are processed by computer and displayed on monitors (55). 

By enabling airport maintenance staff to continuously monitor runway surface

conditions, sensors improve passenger safety and prevent unnecessary application of pavement

deicing/anti-icing agents. Maintenance staff can predict freezing conditions by tracking changes in

pavement temperature and can apply pavement anti-icing chemicals in a timely manner. At

Dallas/Ft. Worth International Airport, for example, runways and taxiway bridges are equipped

with temperature sensors, which let airport personnel monitor pavement conditions and apply

anti-icing agents before pavement temperatures dip below the freezing point. 

Although air temperature can be used to predict the onset of freezing conditions, it

is far less reliable than pavement condition sensors. Changes in pavement temperature generally

lag behind changes in air temperature and can be affected by other factors, such as humidity, wind

velocity, and traffic intensity. Consequently, airports that rely solely on air temperature to decide

when and how anti-icing chemicals should be applied may not be using these chemicals effectively

and may apply chemicals when they are not needed (31, 55). 

The FAA provides guidance to airports considering installing or updating runway

monitoring systems in Advisory Circular 150/5220-13B, Runway Surface Condition Sensor

Specification Guide (55). In this document, FAA recommends installing remote sensors at three

locations on runways: (1) the aircraft touchdown area; (2) the midpoint; and (3) runways exits. 

Runways that are 3,000 feet in length need at least three sensors; longer runways need additional

sensors. The FAA also recommends that sensors be installed on taxiways and aprons (55). In

general, the remote sensors are expensive to install and require frequent maintenance by specially

trained personnel. The cost of installation depends on the number of sensors and the complexity

of the system required. For commercial airports, installing these systems typically costs more than

$100,000 (5). 
Section 6.0 - Pollution Prevention

6-65

One of the leading manufacturers of pavement condition monitoring systems in the

U.S. is Surface Systems, Inc. (SSI), which developed the Road/Runway Weather Information

System (RWISTM) for use by highway maintenance agencies and airport authorities. RWISTM

consists of surface condition sensors, atmospheric sensors, subsurface temperature probes, a data

processing unit, and display software. Data on current pavement conditions is provided by SSI’s

FP2000 sensors, which are installed flush with, and colored to match, the pavement surface. The

FP2000 sensor measures the pavement temperature and can detect surface water and measure its

freezing point, depth, and deicing/anti-icing chemical concentration. Subsurface probes, installed

approximately 17 inches below the FP2000 sensors, are used to measure the ground temperature;

these data are used to predict future pavement surface temperatures. Atmospheric sensors are

installed at the side of the runway and measure air temperature, relative humidity, wind velocity

and direction, and the type and rate of precipitation. Data collected by the atmospheric and

FP2000 sensors are transmitted to a data processing unit, which evaluates and stores the data at

1-minute intervals. The processed data are displayed graphically on monitors with pavement

conditions color-coded. The system can also provide weather forecasts that predict pavement

conditions up to 24 hours in advance. These forecasts are derived by evaluating data provided by

the National Weather Service and SSI’s remote sensors. SSI sensors are currently used at St.

Louis’ Lambert International Airport in Missouri, Springfield’s Capital Airport in Illinois,

Albuquerque International Airport in New Mexico, Ft. Wayne Airport in Indiana, Akron/Canton

Regional Airport in Ohio, and Cincinnati/Northern Kentucky International Airport in Kentucky

(56). 

A similar system, called ICELERTTM, has been developed by Findlay Irvine and is

currently used at commercial airports, military bases, and on highways in Finland, Austria,

Canada, Spain, Italy, Hungary, Britain, and Ireland. ICELERTTM is a surface condition

monitoring system that uses information from pavement surface sensors, ground temperature

probes, and atmospheric sensors to predict icing conditions. ICELERTTM’s sensors measure

pavement surface temperature, concentration of deicing/anti-icing chemicals in surface water,

ambient air temperature, barometric pressure, dew point, wind velocity and direction, and
Section 6.0 - Pollution Prevention

6-66

precipitation. The system uses these data together with information from local meteorological

agencies to provide 24-hour forecasts of pavement conditions (57). 

The principal disadvantage of these systems is the high capital and operating costs

associated with installing and maintaining the remote sensors. These costs can be avoided by

using portable sensors, mounted on airport maintenance vehicles. These devices use infraredbased technology to measure the pavement temperature and display the results on a monitor or

gauge mounted on the vehicle dashboard. Companies currently manufacturing portable pavement

temperature sensors include Sprague Heavy Duty Technology Group and Control Products, Inc. 

The portable sensors cost between $2,500 and $2,700, and are used at some U.S. Air Force bases

(5).

6.6 References

1. Bremer, Karl. The Double Deicing Dilema.

http://www.airportnet.org/depts/publicat/airmags/am91093/deicing.htm (accessed

November 1997) (DCN T4678).

2. U.S. Air Force. Human Systems Center Development Planning Directorate.

Technology Assessment Requirements Analysis for Deicing.

http://xre22.brooks.af.mil/RAsTAs/detoc.htm (accessed November 1997) (DCN

T4679).

3. Noble, Denise L. “Controlling Glycol Runoff,” Environmental Technology. 1997,

7(5), pp 46-48 (DCN T4677).

4. Dennis, Ron. Aircraft Deicing/Anti-icing: Howgozit?

http://www.ftsbn.com/~gsetoday/697_4.htm (accessed November 1997) (DCN

T4675).

5. U.S. Air Force Air Combat Command. Literature and Technology Review Report

for Aircraft and Airfield Deicing. September 1997 (DCN T10450).

6. U.S.A. Today. New Help for Deicing Decisions Being Tested.

http://www.usatoday.com/weather/wpilga.htm (accessed November 1997) (DCN

T4682).
Section 6.0 - Pollution Prevention

6-67

7. U.S. Environmental Protection Agency. Engineering Site Visit Report for

Buffalo-Niagara International Airport, April 15, 1999 (DCN T10352).

8. U.S. Environmental Protection Agency. Meeting Summary: Air Transport

Association of America (Engineering Section). November 1998 (DCN T10464).

9. Betts, Kellyn S. “Airport Pollution Prevention Takes Off,” Environmental Science

and Technology. May, 1999, pp 210-212 (DCN T10558).

10. Premier/Allied Signal promotional literature (DCN T10556).

11. U.S. Air Force Air Combat Command. Installation Management and

Recommendations Report Deicing/Anti-icing Compliance and Requirements

Identification Ellsworth Air Force Base, South Dakota. December 1997 (DCN

T10446).

12. U.S. Air Force Air Combat Command. Installation Management and

Recommendations Report Deicing/Anti-icing Compliance and Requirements

Identification Minot Air Force Base, North Dakota. December 1997 (DCN

T10448).

13. U.S. Air Force Air Combat Command. Final Current Practices Summary Report

for ACC Bases Deicing/Anti-icing Compliance and Requirements Identification.

April 1998 (DCN T10449).

14. Holmgren, Allan and Willis Forsling. A Prestudy of the Recycling Properties of

Aircraft De-/Anti-icing Fluids. http://www.lath.se/depts/lib/coldtech/ct95-1.html

(accessed October 1998) (DCN T10478).

15. Lopez, Ramon. U.S. Acts to Tighten Deicing Controls. (DCN T218).

16. Catalyst and Chemical Services, Inc., product literature (DCN T11044).

17. Canada News Wire. http://www.newswire.ca/releases/January1997/16/c2465.html

(accessed Nov. 1997) (DCN T4680).

18. Federal Aviation Administration. http://www.dot.gov/affairs/apa5197.htm

(accessed Nov. 1997) (DCN T4681).

19. Radiant Energy Corporation promotional literature (DCN T10445).

20. Bremer, K. “The Three Rs: Reduce, Recover and Recycle,” Airport Magazine.

March/April 1998, pp 42-49 (DCN T10361).
Section 6.0 - Pollution Prevention

6-68

21. Rhinelander/Oneida County Airport. Taxi Thru Infrared Pre-flight Deicing System.

http://www.rhiairport.com/deicer/deicer.htm (accessed October 1998) (DCN

T10470).

22. Letter from John Giannone, Radiant Aviation Services, Inc., to Shari H. Zuskin,

U.S. EPA. November 22, 1999 (DCN T11075).

23. Infra-Red Technologies, Inc. promotional literature (DCN T10354).

24. Sun Lase, Inc. promotional literature (DCN T10480).

25. Dennis, Ron. Deicing/Anti-icing Update. http://gsetoday.com/back-is/June98/

DeicingUp.htm (accessed October 1998) (DCN T10476).

26. U.S.A.F. Pro-Act Fact Sheet: Air Force Aircraft and Airfield Deicing/Anti-icing.

http://www.afcee.brooks.af.mil/pro_act/fact/May98.htm (accessed October 1998)

(DCN T10472).

27. Combs, J., et al. Deicing P2/Best Management Practices. Proceedings of the Air

Combat Command Environmental Training, Houston, TX, 1997 (DCN T10379).

28. Mericas, D. and B. Wagoner. “Balancing Safety and the Environment,” Water

Environment and Technology. December 1994, pp 38-43 (DCN T9971).

29. BF Goodrich Aerospace, promotional literature (DCN T10557).

30. Kennon Sun Shields. http://www.avweb.com/sponsors/kennon/ieycover.html

(accessed December 1998) (DCN T10479).

31. Federal Aviation Administration. Airport Winter Safety and Operations. Advisory

Circular No. 150/5200-30A. Washington, DC. 1991 (DCN T10427).

32. U.S. Environmental Protection Agency. Engineering Site Visit Report for Albany

International Airport. November 5, 1999 (DCN T10534).

33. National Center for Environmental Research and Quality Assurance.

http://es.epa.gov/ncerqa_abstracts/sbir/other/pp/westmark.html (accessed February

1998) (DCN T9973).

34. Wilson, Richard. Polaris Vienna Presentation. Presented at the SAE G-12 Future

Deicing Technology Development Adhoc Subcommittee, Vienna, Austria, May

1998 (DCN T10561).
Section 6.0 - Pollution Prevention

6-69

35. Federal Aviation Administration. Design of Aircraft Deicing Facilities. Advisory

Circular 150/5300-14. Washington, DC. 1993 (DCN T10473).

36. Decelles, Richard. New Facility Approaches: Montreal International Airport.

Presented at The Seventh Annual Aircraft and Airfield Deicing Conference and

Exposition, Washington, DC. August 1998 (DCN T10395).

37. Greater Toronto Airports Authority promotional literature (DCN T10550).

38. A/S Roulunds Fabriker promotional literature (DCN T9974).

39. Environmental Cleaning Systems, Inc. promotional literature (DCN T4671).

40. Aviation Environmental, Inc. promotional literature (DCN T10477).

41. AR Plus Equipment Rentals (USA), Inc. promotional literature (DCN T10394).

42. Fronapfel, P.J. and P.A. Malinowski. “Deicing,” The Military Engineer. October

1997, pp 53-54 (DCN T9972).

43. Tennant promotional literature and private correspondence (DCN T10486, DCN

T10593, DCN T10594).

44. Tymco, Inc. promotional literature (DCN T10499).

45. AR Plus Equipment Rentals (USA), Inc. promotional literature (DCN T10397).

46. Letter from James H. Eldert, AR Plus Site Services (Canada) Inc. To Shari

Zuskin-Barash, U.S. EPA. December 20, 1999 (DCN T11082).

47. AR Plus Equipment Rentals (USA), Inc. promotional literature (DCN T10396).

48. Trecan Combustion Limited, promotional literature (DCN T11020).

49. U.S. Environmental Protection Agency. Emerging Technology Report: Preliminary

Status of Airplane Deicing Fluid Recovery Systems. EPA 832-B-95-005. 1995

(DCN T4674). 

50. U.S. Environmental Protection Agency. Engineering Site Visit Report for Denver

International Airport. September 2, 1998 (DCN T10295).

51. U.S. Environmental Protection Agency. EPA Deicing Study Technology

Questionnaire: The Environmental Quality Company (DCN T11047).
Section 6.0 - Pollution Prevention

6-70

52. Inland Technologies, Ltd. promotional literature (DCN T10363, DCN T10370).

53. Superior Graphite Company, promotional literature (DCN T11011).

54. Small Business Innovation Research Program. 

http://sbir.gsfc.nasa.gov/95abstracts/06.01/950901.html (accessed September

1999) (DCN T11012).

55. Federal Aviation Administration. Runway Surface Condition Sensor Specification

Guide. Advisory Circular No. 150/5220-13B. Washington, DC. 1991 (DCN

T10696).

56. Surface Systems, Inc., promotional literature (DCN T11016).

57. Findlay, Irvine Ltd., promotional literature (DCN T11017).
Section 7.0 - Wastewater Containment and Treatment

7-1

7.0 WASTEWATER CONTAINMENT AND TREATMENT

Many airports have installed wastewater containment and treatment systems, often

in combination with pollution prevention controls described in Section 6.0, to comply with

discharge requirements for storm water contaminated with deicing agents. This section describes

the types of containment and treatment technologies used by airports and available treatment

performance data for these technologies. Table 7-1, at the end of this section, summarizes the

airport systems described in this section; costs for these systems are included in Section 11.0.

Note that the glycol recycling systems described in Section 6.4 also serve as “wastewater

treatment” in that they remove glycol and other pollutants of concern from airport deicing/antiicing fluids (ADF)-contaminated wastewater. Appendix A contains information regarding the

location of airports referenced in this section.

7.1 Wastewater Containment

Of significant concern for contaminated storm water discharges, both directly to

surface waters and indirectly to publicly owned treatment works (POTWs), is the high variability

and unpredictability in hydraulic and pollutant loading. Airports have large impervious areas for

gates, aprons, ramps, taxiways, runways, roads, and parking lots, which contribute to hydraulic

loading. Major winter storms can require application of large amounts of aircraft and pavement

deicing chemicals within a short period of time that can result in a “slug” loading of these

chemicals in storm water discharges. To help mitigate storm water flow variability and slug

discharges, many airports have constructed storm water containment systems either as part of the

original airport design or in response to more recent storm water discharge requirements. 

Common types of storm water containment at airports are retention ponds, underground storage

basins, and storage tanks.

The cost of these structures and their associated drainage systems is directly

proportional to the size of the area serviced by the system and the volume of precipitation

expected. As a result, at most airports, these systems service only those areas where aircraft
Section 7.0 - Wastewater Containment and Treatment

7-2

deicing operations are performed. Furthermore, many airports also incorporate diversion devices

(e.g., valves and gates) such that deicing operation areas are only serviced when glycol or a

surrogate parameter is detected in storm water, which further reduces the size and cost of the

containment system. EPA identified several airports that use containment systems to control

discharges of ADF-contaminated wastewater to surface waters and POTWs (described below),

and believes other airports may have constructed containment systems.

Runoff from runways and other large paved areas are generally discharged without

treatment because of the high cost of controls. However, discharges from these areas may

contain high pollutant loadings. For example, during a 1998 conference and exposition sponsored

by the American Association of Airline Executives and the Airport Council International - North

America, a consultant working for Portland International Airport indicated that runway deicing

operations contributed one-third of total deicing-derived biochemical oxygen demand (BOD)

discharges to surface waters. Although many airports have stopped using glycol-based chemicals

for pavement deicing, their increased use of Type IV deicing fluids, designed to shear from

aircraft surfaces during takeoff, may contribute to pollutant loadings discharged from runway

areas. EPA currently knows of only one U.S. airport, Chicago’s O’Hare International Airport,

and two European airports, Munich Airport in Germany and Stockholm-Arlanda Airport in

Sweden, that collect a portion or all of the contaminated storm water from runways and taxiways. 

Airport wastewater containment systems are also described below.

Portland International Airport, Portland, OR (PDX)

Currently, ADF-contaminated wastewater from the gate areas is discharged

directly to the Columbia Slough via nine major outfalls. The Columbia Slough flows to the

Willamette River (1).

A long-term plan being developed jointly between the airport and the airlines, in

accordance with a NPDES permit issued by the Oregon DEQ, includes an airport-wide deicing

runoff containment system. The system will use in-line BOD meters to monitor glycol
Section 7.0 - Wastewater Containment and Treatment

7-3

concentrations in runoff. Higher-strength ADF-contaminated wastewater collected near the

terminal areas will be conveyed to storage tanks followed by controlled discharge to a POTW. 

Lower strength wastewater will be diverted to a 13-million-gallon, aerated retention pond for

biological pretreatment prior to controlled discharged to the Columbia Slough in compliance with

the waste load allocations for BOD5 specified in the Columbia Slough TMDL. See Section 13.2.2

for a description of Portland’s TMDL-based permit (1, 2).

Billings Logan International Airport, Billings, MT (BIL)

Storm water contaminated with ADF enters the storm drain system that flows to

four detention ponds operated in series. Storm water enters the first pond, which overflows to

the second pond, and so forth. Overflow from the fourth pond is discharged to a nearby creek. 

In general, the first pond is large enough to contain all glycol-contaminated wastewater generated

during the winter. Spring precipitation then usually fills all four ponds, resulting in the eventual

discharge of the collected glycol-contaminated wastewater. Airport personnel indicated that most

of the glycol has biodegraded in the ponds prior to discharge.

Chicago O’Hare International Airport, Chicago, IL (ORD)

Deicing/anti-icing fluids from all of the aircraft deicing/anti-icing areas and 50% to

70% of the pavement enter Chicago O’Hare International Airport’s storm water drainage systems

and are collected and retained in one of the airport’s two storm water detention ponds, the South

Detention Pond and the North Airfield Detention Pond. The South Detention Pond has a capacity

of approximately 1,120 acre-feet and services the southern part of the airfield, which includes

wastewater from aircraft deicing/anti-icing operations conducted at the airport’s passenger

terminals and cargo ramps. The Northern Detention Pond has a capacity of 45 acre-feet and

services an aircraft deicing pad storm water drainage system. Both ponds discharge at a

controlled rate to local POTWs. Total wastewater discharge fees range from $800,000 to $1

million per year and are based on the volume of wastewater treated, BOD5, and suspended solid

loadings.
Section 7.0 - Wastewater Containment and Treatment

7-4

Contaminated storm water from the northern part of the airfield, including portions

of two runways and their associated taxiways, drains into nearby creeks. Airport managers are

working on plans to construct a storm drainage system around these runways and taxiways, which

will collect the contaminated storm water and convey it through underground pipes to a detention

pond for eventual discharge to a POTW.

Minneapolis-St. Paul International Airport, Minneapolis, MN (MSP)

Minneapolis-St. Paul International Airport uses compression plugs in their storm

water system (discussed in Section 6.3.2) to collect ADF-contaminated wastewater for

subsequent glycol recycling/recovery. The airport estimates that more than 40% of all fluid

applied is collected in the storm water retention system. However, some collected wastewater is

too dilute for economically viable glycol recycling/recovery. Dilute wastewater is evacuated as

needed using pump trucks and transported to one of two 1-million-gallon, nonaerated storage

ponds dedicated for lower strength wastewater. (Three ponds and associated equipment,

including a boiler and recirculation system to protect against pond freezing, were constructed in

1993 at a cost of $1 million.) The ponds are alternately filled and then slowly discharged to the

POTW. On average, the low-strength ponds contain wastewater with propylene glycol

concentrations of 2 percent. Wastewater discharge fees include $0.056 per pound of chemical

oxygen demand (COD) for concentrations greater than 500 mg/L, as well as sewerage fees

assessed by wastewater volume, for a total annual cost ranging from $150,000 to $200,000.

Dallas/Ft. Worth International Airport, Dallas, TX (DFW)

In 1999, the Dallas/Ft. Worth International Airport constructed nine deicing pads

at a cost of over $16 million for deicing/anti-icing operations with a total of 53 aircraft positions. 

The airport is now able to collect and contain all ADF runoff generated on these pads. The

deicing pads are strategically located around the airport near both runway thresholds and terminal

egress taxiways. All pads are common use facilities, and each airline is free to select the pad that
Section 7.0 - Wastewater Containment and Treatment

7-5

best suits its needs. Operational experience has shown that the airlines primarily use the threshold

pads during intense periods of deicing.

When deicing/anti-icing activities are occurring, the runoff from the pads is

directed to collection tanks located at each deicing pad. The collection tanks have a combined

volume of over 1.5 million gallons and can be emptied by tank trucks within 24 hours. 

Precipitation and runoff from the pads immediately after deicing is also collected to ensure that no

residual deicing fluid remains.

The airport has contracted the collection of deicing runoff to Inland Technologies. 

Inland is obligated to pick up by tank truck all fluid collected in the collection tanks. Depending

on the concentration of the runoff, or their system capacity, Inland may either recycle, biologically

treat on site, or ship off site the fluid they collect. For biological treatment, Inland will use the

airport’s detention ponds which were constructed in 1997 at a cost of $1.7 million. The ponds

are covered and lined with membranes. The combined capacity of the detection ponds is 6 million

gallons. Following biological treatment, the fluid may be discharged to the POTW, which

requires the wastewater to have a BOD5 of less than 250 mg/L. The POTW charges a hydraulic

loading fee of $1.07/1,000 gallons.

Following completion of deicing/anti-icing operations, the airport ensures that any

ADF runoff remaining on the pads is removed prior to directing runoff to the airport’s 

pretreatment system. This system is specially designed to collect “first flush” precipitation

contaminated with oil and grease from spills on ramps and gate areas. Specifically, storm water

enters drains and flows to diversion boxes that each contain an inflow pipe and two outflow pipes

positioned one above the other. The lower outfall pipes drain to the airport’s pretreatment plant. 

The upper outfall pipes discharge to the airport’s general storm water collection system and

ultimately to U.S. surface waters during periods of high storm flow (3).
Section 7.0 - Wastewater Containment and Treatment

7-6

Denver International Airport, Denver, CO (DIA)

At Denver International Airport, aircraft deicing operations are performed

primarily at specially designed deicing pads (discussed in Section 6.3.1) where large volumes of

high concentration ADF-contaminated wastewater are collected for glycol recycling/recovery. In

addition, limited aircraft deicing is performed in the gate areas. Airport personnel estimate that

approximately 70% of all ADF applied at the deicing pads and gate areas is subsequently

collected. Runoff from the gates flows by gravity to the east and west detention ponds, which

have a combined capacity of 12 million gallons. The ponds are a component of a large

wastewater collection system project constructed in 1995 at a total cost of $36 million. (Airport

construction was completed in 1994, and airfield operations began in 1995.) One of the ponds is

separated into two cells. When the first cell is full, the wastewater is pumped to the second cell,

where it is mixed for 12 hours to homogenize the wastewater prior to discharge. Since the other

pond has only one cell, this pond is not mixed prior to discharge. The wastewater from each pond

is tested to determine its characteristics and discharged at a controlled rate to the POTW. The

POTW places surcharges on excess BOD, total Kjeldahl nitrogen, and hydraulic flow. Airport

personnel stated that these surcharges total approximately $550,000 per year.

Salt Lake City International Airport, Salt Lake City, UT (SLC)

Salt Lake City International Airport has constructed specially designed aircraft

deicing areas where runoff is collected for subsequent glycol recycling/recovery (see Section

6.4.1, Environmental Quality Company (EQ)). However, some collected wastewater is too dilute

for economically viable glycol recycling/recovery. EQ dedicated one of three, newly constructed,

3-million-gallon detention ponds for lower-strength wastewater, which is discharged to a POTW. 

The ponds are part of a large wastewater collection system and glycol recycling/recovery project

constructed in 1998 at a total cost of $28 million. Each detention pond is lined with clay and a

membrane liner, and covered with a floating membrane to reduce degradation of glycol by

ultraviolet light and bacterial action. Currently, wastewater with BOD concentrations greater than

200 mg/L are subject to a POTW surcharge of $0.05/lb BOD.
Section 7.0 - Wastewater Containment and Treatment

7-7

Buffalo-Niagara International Airport, Buffalo, NY (BUF)

In areas where aircraft deicing/anti-icing operations are performed, BuffaloNiagara International Airport installed storm water collection systems equipped with diversion

valves to direct storm water to either an underground storage basin (ADF-contaminated

wastewater) or an underground storm water detention basin (non-ADF-contaminated

wastewater). The ADF-contaminated wastewater storage basin is lined with a membrane and has

four chambers, each with a capacity of 50,000 gallons. Wastewater from the storage basin is

discharged to a POTW, which requires the airport to meter their discharge based on glycol

loading. Wastewater with BOD concentrations greater than 250 mg/L is subject to an additional

surcharge of between $0.10 and $0.105 per gallon. The annual BOD surcharge ranges from

$1,800 to $2,400.

Kansas City International Airport, Kansas City, MO (MCI)

In the main gate and terminal areas where aircraft deicing/anti-icing operations are

performed, Kansas City International Airport is upgrading their existing storm water collection

systems to include diversion valves to direct storm water to either a concrete storage basin (ADFcontaminated wastewater) or a series of storm water retention ponds (non-ADF-contaminated

wastewater). The storage basin consists of two, 1-million-gallon chambers operated in parallel

with one filling while the second is discharging to the POTW. Wastewater is discharged at a

controlled rate based on flow and BOD loading. 5

The Federal Aviation Administration (FAA) and Kansas City International Airport

funded modifications to the POTW to handle the ADF-contaminated wastewater discharged from

the airport. The total capital cost of upgrading the storm water collection system, installing the

storage basin, and upgrading the POTW is estimated to be $8.5 million, of which 75% will be

funded by the FAA and the remainder by the airport.
Section 7.0 - Wastewater Containment and Treatment

7-8

Baltimore/Washington International Airport, Baltimore, MD (BWI)

Baltimore/Washington International Airport has invested approximately $22

million on deicing control facilities including three deicing pads, each equipped with runoff

drainage and collection systems, storm water diversion trenches at multiple locations at the

passenger terminal gates, and glycol vacuum trucks. Under nondeicing conditions, storm water is

directed to the airport storm water drainage system. During deicing events, diversion valves are

actuated to direct ADF-contaminated wastewater to collection vaults for transfer to temporary

storage tanks. Two of the three deicing pads each include two 20,000-gallon, above-ground

temporary storage tanks. Wastewater from these tanks is transported to the third deicing pad via

tank truck. The third deicing pad includes a lift station to transfer wastewater from all three

deicing pads to a central wastewater storage area, which includes a 600,000-gallon, above-ground

storage tank surrounded by a 5- to 6-foot concrete containment wall. From the central storage

area, wastewater is discharged at a controlled rate to the POTW based on BOD loading. 

Wastewater discharge fees are $0.0024 per gallon (4).

Des Moines International Airport, Des Moines, IA (DSM)

All aircraft deicing operations are performed on an apron rebuilt in 1995 to allow

collection of all runoff from this area. The airport collects approximately 30% of all ADF applied.

The airport is currently constructing a 4-million-gallon storage tank (cost: $8 million) to contain

runoff from the apron beginning in the 1999/2000 deicing season (2). During the winter months,

when deicing events are likely to occur, wastewater from the tank will be discharged at a

controlled rate to the POTW. For the remainder of the year, the tank contents will be discharged

directly to surface waters. The tank will be equipped with a TOC analyzer to indicate the

presence of glycol.
Section 7.0 - Wastewater Containment and Treatment

7-9

Hopkins International Airport, Cleveland, OH (CLE)

Hopkins International Airport uses compression plugs (discussed in Section 6.3.2)

in their storm water system to collect ADF-contaminated wastewater for subsequent glycol

recycling/recovery. However, they consider some of the collected wastewater to be too dilute

(i.e., less than 11% glycol content) for economically viable glycol recycling/recovery. Dilute

wastewater is evacuated as needed using pump trucks and transported to one of eight 21,000-

gallon storage tanks dedicated for lower-strength wastewater. Dilute wastewater from the

storage tanks is then discharged at a controlled rate to the POTW. Wastewater discharge fees are

$0.04 per gallon.

Washington Dulles International Airport, Herndon, VA (IAD)

Washington Dulles International Airport is implementing an ADF-contaminated

wastewater collection and storage system for use beginning in the 1999/2000 deicing system. 

Wastewater will be collected from deicing operation areas using glycol vacuum vehicles (see

Section 6.3.5) and transferred to storage tanks. Wastewater with high glycol content (7% or

greater) will be stored in a 500,000-gallon storage tank and in twenty 20,000-gallon storage tanks

for eventual transport for on-site glycol recycling/recovery. Dilute wastewater (<7%) will be

stored in a 300,000-gallon storage tank for discharge at a controlled rate to a POTW. The airport

plans to begin discharging to the POTW in January 2000.

Prior to implementing this system, most storm water runoff at Washington Dulles

International Airport, including that from the primary and two of the three secondary deicing

areas, drained into Horsepen Lake, a man-made impoundment, either by overland flow or through

storm drains after traveling three to four miles. The total drainage area for the lake is 23 square

miles. Water from the lake is discharged to Broad Run, a tributary to the Potomac River.
Section 7.0 - Wastewater Containment and Treatment

7-10

Munich Airport, Germany (MUC)

At Munich Airport, a system of drainage channels connected to underground pipes

is used to collect contaminated storm water from the runways and convey it to a wastewater

storage complex. The storage complex consists of an underground concrete storage basin with a

capacity of 16 million gallons and a lined detention basin with a capacity of 21 million gallons. 

Wastewater from the storage complex is discharged at a controlled rate to a local wastewater

treatment plant. Contaminated storm water from the airport’s taxiways is also collected and

treated on site as described in Section 7.2.3 (5).

Stockholm-Arlanda Airport, Sweden (ARN)

Stockholm-Arlanda Airport installed a high-density polyethylene membrane with a

bentonite and sand lining beneath the airport’s new runway to prevent seepage of aircraft and

pavement deicing/anti-icing chemicals into an aquifer that lies directly beneath the runway. The

membrane collects storm water from the runway and diverts it to a storm water drainage system. 

The membrane is monitored using leak detection equipment and groundwater monitoring wells

(5).

7.2 Wastewater Treatment

This section describes on-site wastewater treatment used by airports to control

deicing chemical discharges to surface waters and POTWs.

7.2.1 Biological Treatment

Because of the high oxygen demand of ADF-contaminated wastewater, many

airports rely on biological treatment as a cost-effective and efficient treatment technology. The

principle advantages of biological treatment specific to airport deicing operations include: (1)

capability to treat both high-strength and dilute wastewaters, (2) capability to treat wastewater
Section 7.0 - Wastewater Containment and Treatment

7-11

containing ethylene glycol, propylene glycol, or a mixture of both, (3) capability for use with any

wastewater collection system (systems described in Sections 6.3 and 7.1), and (4) competitive

treatment costs as compared to glycol recycling. Where feasible, airports generally choose offsite biological treatment via discharge to a POTW. Table 13-1, at the end of this section, lists

facilities known to discharge to a POTW and their discharge requirements. However, several

airports choose on-site biological treatment for a variety of reasons including: (1) limited

hydraulic or loading capacity at the POTW, (2) high POTW wastewater treatment and/or

conveyance fees, (3) inability of local POTW to handle highly variable pollutant loadings, and (4)

airport infrastructure constraints. Wastewater treatment at these airports is described below.

Airport biological treatment systems generally include a means of wastewater

equalization to avoid system upset by flow variability and slug loadings. Airports using pondbased biological treatment systems generally use their ponds for both wastewater equalization and

wastewater treatment (see discussion of Greater Rockford Airport below). Other airports use

ponds solely for wastewater equalization. For example, Albany International Airport, discussed

below, operates extensive wastewater equalization in ponds prior to biological treatment.

Note that any airport operating contaminated storm water containment systems,

where wastewater is retained through warmer spring months, likely achieves some degree of

natural biological degradation of glycol prior to discharge. One example is Billings Logan

International Airport discussed earlier in this section.

Greater Rockford Airport, Rockford, IL (RFD)

Greater Rockford Airport operates an aerobic biological treatment system

consisting of a 16-million-gallon aerated detention pond, a settling pond, a recycling pump, and a

chemical addition building. The system was constructed in 1994 at a capital cost of $1.8 million. 

Estimated annual operating costs (i.e., electricity, chemicals) are $108,000 and estimated annual

labor costs are $60,000 to $75,000. Contaminated storm water enters a detention pond, which is

lined and fitted with four mechanical and 12 aspirating aerators. Wastewater is retained in the
Section 7.0 - Wastewater Containment and Treatment

7-12

detention pond during the deicing season, and released in spring or early summer. During this

time, microorganisms present in the pond biodegrade ethylene and propylene glycols. The

biodegradation of glycol is temperature-dependent and mainly occurs during the spring and early

summer months when ambient temperatures are higher. Airport personnel estimate that the BOD5

of contaminated storm water entering the detention pond during the deicing season may reach a

high of 2,000 mg/L. By midsummer, biodegradation has reduced the BOD5 to less than 30 mg/L

(typically 10 mg/L). Prior to discharge, the treated wastewater is transferred to the 5-milliongallon settling pond and then slowly discharged to the Rock River over a two- to three-week

period. 

The pond system has operated for five years with minor sludge buildup that has

not required removal. Airport personnel anticipate that any sludge removed from the ponds in the

future would be land-applied on site.

The table below presents EPA’s sampling data for Greater Rockford Airport’s

wastewater treatment system. Note that during the 1998-1999 deicing season (when EPA

collected samples at Greater Rockford Airport), BOD5 concentrations in the pond did not exceed

100 mg/L. In addition, during the three-week period immediately preceding collection of the

influent sample, ambient temperatures were unseasonably warm with daily highs reaching above

70EF on five separate days. Consequently, EPA believes that some treatment had already

occurred prior to collection of the influent sample. This conclusion is further supported by the

analytical data, which shows that glycols, known to biodegrade rapidly, were not detected in the

influent sample. Note that the treatment system removed toxic additives (e.g., tolyltriazole).
Section 7.0 - Wastewater Containment and Treatment

7-13

Pollutant Influent Concentration Effluent Concentration

Propylene Glycol (mg/L) ND (5) ND (5)

Ethylene Glycol (mg/L) ND (10) ND (10)

Tolyltriazole (mg/L) 0.12 0.013

Phenol (ug/L) ND (10) ND (10)

Total Organic Carbon (mg/L) 12 9.0

Ammonia as Nitrogen (mg/L) 46 0.27

Hexane Extractable Material (mg/L) 100 ND (6)

ND - Not detected (followed by the detection limit).

The airport submitted weekly monitoring data for the wastewater treatment facility

detention pond for September 28, 1998 through July 7, 1999. The airport also submitted daily

discharge monitoring data for July 20, 1999 through August 26, 1999. These data are

summarized below. 

Pollutant Average Range Average Range

Detention Pond Concentration Discharge Concentration

Biochemical Oxygen Demand, 5-Day 37 ND (10) - 98 5.3 3 - 10

(mg/L)

Ammonia as Nitrogen (mg/L) 24 ND (0.5) - 82 0.5 0.5 - 0.55

Total Suspended Solids (mg/L) 38 ND (5) - 325 7.1 ND (5) - 12

Duluth International Airport, Duluth, MN (DLH)

Duluth International Airport operates storm water retention ponds equipped with

aeration systems to biologically degrade glycol and improve water quality prior to discharge to

surface waters. The airport plans to upgrade the aeration system to include filtration and

chlorination.
Section 7.0 - Wastewater Containment and Treatment

7-14

Albany International Airport, Albany, NY (ALB)

Albany International Airport operates an anaerobic biological treatment system

consisting of two fluidized bed biological reactors currently operated in parallel with the capability

of operating in series when required. Each unit is 14 feet in diameter, 35 feet in height (including

a 4-foot freeboard), and packed with 10 tons of granular activated carbon. The treatment system

was constructed in 1998 at a capital cost of $3.2 million and is preceded by a total of 11 million

gallons of deicing storm water retention and equalization (retention ponds and a storage tank). 

The airport collects and treats approximately 70% of all ADF applied.

The treatment system was designed and constructed by EFX Systems, Inc. and

Clough-Harbour Technical Services, LLC to meet the Airport Authority’s design-build

performance specifications. These requirements included: (1) a minimum influent flow rate of

100 gallons per minute (an annual total of 31 million gallons), (2) reduction of the propylene

glycol concentration from an average of between 4,800 and 7,500 mg/L to below the detection

limit of 1 mg/L, and (3) reduction of COD by greater than 90 percent.

Deicing storm water is recirculated through the unit to increase the residence time

and equalize influent characteristics. Under anaerobic operating conditions, glycol is converted

primarily to methane gas, carbon dioxide, and biomass. Some glycol is also converted to

propionic acid. The system is self-sustaining by reusing methane for process and space heating. 

Final effluent is stored prior to either commercial spray irrigation to the airfield or discharge to the

POTW during winter months. The system includes separators to capture and return carryover

bed carbon. Excess biomass, which is too fine to be removed by the separators, exits with

effluent for discharge through airfield spray irrigation.

EPA’s sampling data for Albany International Airport are presented below. Note

that the treatment system removed toxic additives (e.g., tolyltriazole) as well as glycol. This

analysis was conducted prior to establishment of aerobic polishing filtration units, which

reportedly reduce effluent to below threshold limits for all permit parameters.
Section 7.0 - Wastewater Containment and Treatment

7-15

Pollutant Influent Concentration Effluent Concentration

Propylene Glycol (mg/L) 2,700 ND (5)

Ethylene Glycol (mg/L) ND (10) ND (10)

Tolyltriazole (mg/L) >2.00 0.107

Phenol (ug/L) 109 ND (10)

Total Organic Carbon (mg/L) 2,420 ND (10)

Ammonia as Nitrogen (mg/L) (a) 88.1 87.2

Hexane Extractable Material (mg/L) ND (6) ND (5.5)

ND - Not detected (followed by the detection limit).

(a) According to airport personnel, the ammonia concentration indicates an anomaly condition not representative of

typical deicing wastewater at Albany International Airport. Subsequent ammonia analysis conducted by the airport

established maximum effluent concentrations of less than 45 mg/L. Subsequent to EPA’s sampling episode, the airport

installed an aerobic polishing filtration unit, which reportedly reduces ammonia concentrations to less than 5 mg/L.

The airport installed and began operating the EFX biological treatment system

during the 1998-1999 deicing season. The system was required to undergo an acceptance period

where the system was operated 30 consecutive days at an average daily applied loading rate of

3,500 kg COD/day (10% above the design maximum loading rate). The results from this

acceptance period are presented below.

Pollutant Average Range Average Range

Influent Concentration Effluent Concentration

Propylene Glycol (mg/L) 4,400 3,400 - 5,500 0.28 ND (0.05) - 0.85

Biochemical Oxygen Demand, 5-Day NA NA 57 39 - 75

(mg/L)

Chemical Oxygen Demand (mg/L) 8,600 420 - 9,300 110 70 - 610

NA - Not available.

Airborne Air Park, Wilmington, OH (ILN)

Airborne Air Park operates a pilot-scale reciprocating subsurface aerobic/

anaerobic biological treatment system in which glycol-contaminated wastewater flows through

beds of gravel that is planted with wetland plants. The reciprocating design, whereby wastewater

is alternately transferred between pairs of partner cells, enhances biological degradation. The fullscale system is currently under construction for use beginning in the 2000-2001 deicing season to
Section 7.0 - Wastewater Containment and Treatment

7-16

treat all dry-weather flows and nonpeak wet-weather flows from areas where aircraft deicing is

performed. Airport personnel estimate that 90% of ADF-contaminated wastewater will be treated

by the system. The cost of the treatment system is not known.

Biological degradation occurs primarily via bacteria attached to the gravel and

secondarily by the wetland plants. Bacteria populations are both aerobic and anaerobic, with

aerobic bacteria degrading glycols and anaerobic bacteria degrading excess biological solids. 

Performance data for the pilot-scale treatment system are presented below.

Subsurface (lb COD per Average Average Influent COD Range of

Treatment mgal per ft of Influent COD Effluent COD Treated Effluent COD

System Type substrate) (mg/L) (mg/L) (mg/L) (mg/L)

Removal Rate Range of

3

Conventional 0.6 959 783 100 to 500 24 to 380

Reciprocating 7.5 1960 383 260 to 12,000 42 to 2,990

7.2.2 Oil/Water Separation

Some airports operate oil/water separators to mitigate any potential petroleum

spill. Chicago O’Hare International Airport operates an oil/water separator consisting of a

skimmer and underflow weir at each inlet to its storm water retention pond. Greater Rockford

Airport operates a static inclined plate oil/water separator prior to the inlet to its aerated detention

pond. Seattle/Tacoma International Airport in Washington State separately conveys

contaminated storm water collected from areas where aircraft deicing operations are performed

and industrial wastewater generated at the airport to an on-site industrial waste treatment system. 

The system consists of storage/equalization, settling, and dissolved air flotation prior to its

discharge to the Puget Sound. (Note that the airport plans to discharge to a POTW in the future.) 

Dallas/Ft. Worth International Airport incorporates baffles in storm water diversion boxes to

separate any oil and grease. In addition, ADF-contaminated wastewater is routed through a grit

chamber and oil skimmer prior to entering the airport’s new detention basins. Anchorage

International Airport in Alaska operates watershed protection stations which include (in addition

to other controls described in Section 7.2.3) oil/water separators to skim and remove petroleum
Section 7.0 - Wastewater Containment and Treatment

7-17

products from drainage ditches flowing to nearby lakes. Oil/water separation is not useful in

removing glycol and other dissolved pollutants in ADF-contaminated wastewater.

7.2.3 Land Application

Albany International Airport disposes of some of its effluent from their on-site

anaerobic biological treatment system via airfield spray irrigation as a cost-effective alternative to

discharging to the POTW. Installation of the irrigation pipe gallery array covering approximately

40 acres cost less than $110,000 plus airfield maintenance labor. Spray irrigation is performed at

a rate of 150 gallons per minute and BOD loading of less than 10 pounds of BOD per acre per

day. Their New York State discharge permit allows irrigation discharge of up to 500 pounds of

BOD per acre per day when soil temperatures are above 50E F. Biological treatment plant

effluent is continuously monitored via a 24-hour composite sampler to ensure adherence to permit

requirements.

Almost all U. S. airports maintain vegetative swales between impervious areas to

help mitigate storm water runoff and allow deicing chemicals to degrade naturally. For example,

Anchorage International Airport maintains oversized open drainage swales to allow natural

biodegradation, filtration, settling, and evaporation of storm water runoff. To a limited extent,

existing wetland receive some of the ADF-contaminated storm water for natural degradation. 

Duluth International Airport conveys some ADF-contaminated storm water to retention areas that

do not drain to surface waters, where the storm water is allowed to evaporate and infiltrate the

ground.

Baltimore/Washington International Airport has constructed infiltration facilities

throughout its airfield designed to temporarily store and infiltrate runoff from the first one-half

inch of each rain event into the underlying soils. The infiltration facilities consist of gravel-filled

trenches installed parallel to runways and taxiways. Excess water overflows the trenches and is

directed either to storm water retention areas or to specially designed overland flow through grass

meadow strips and a shrub bed prior to discharge (6).
Section 7.0 - Wastewater Containment and Treatment

7-18

At the Munich Airport, contaminated storm water from the airport’s taxiways is

collected and treated by a specially designed biodegradation system installed approximately 1 foot

beneath the taxiway surface. This system consists of two layers of impervious fabric enclosing a

1-mm thick layer of bentonite powder. The top fabric layer is overlain with a layer of loosely

packed sand, which is seeded with bacteria to biodegrade aircraft and pavement deicing/anti-icing

chemicals (4).

7.3 References

1. Letter from Cheryl R. Koshuta, Port of Portland, to Shari H. Zuskin, U.S. EPA. 

November 1, 1999 (DCN T11067).

2. Letter from Scott F. Belcher, Air Transport Association, to Shari Zuskin Barash,

U.S. EPA. November 4, 1999 (DCN T11063).

3. Letter from Darcy Zarubiak, Dallas/Ft. Worth International Airport, to Shari

Zuskin, U.S. EPA. December 22, 1999 (DCN T11085).

4. Maryland Aviation Administration. Aircraft Deicing Plan Update,

Baltimore/Washington International Airport. August 1998 (DCN T10697).

5. U.S.A.F. Air Combat Command. Literature and Technology Review Report for

Aircraft and Airfield Deicing. September 1997 (DCN T10450).

6. Maryland Aviation Administration. Interim Report, Mass Balance Study Aircraft

Glycol Deicers, Baltimore/Washington International Airport. September 1998

(DCN T10698).
Section 7.0 - Wastewater Containment and Treatment

7-19

Table 7-1

Summary of Wastewater Containment and Treatment at Airports

Airport Wastewater Collection/Treatment

ADF-Contaminated

Portland International Airport (PDX) High strength to POTW

Low strength to pond and direct discharge

Billings Logan International Airport (BIL) Retained in a series of ponds; direct discharge in spring

Chicago O’Hare International Airport (ORD) Retained in ponds; discharge to POTW

Minneapolis-St. Paul International Airport (MSP) High strength to glycol recycling

Low strength to ponds; discharge to POTW

Dallas/Ft. Worth International Airport (DFW) Retained in detention basins; discharge to POTW

Denver International Airport (DIA) Deicing pad runoff to glycol recycling. Gate runoff to

detention ponds; discharge to POTW

Salt Lake City International Airport (SLC) High strength to glycol recycling

Low strength to detention pond; discharge to POTW

Buffalo-Niagara International Airport (BUF) Retained in underground storage basins; discharge to

POTW

Kansas City International Airport (MCI) Retained in storage basins; discharge to POTW

Baltimore/Washington International Airport (BWI) Retained in storage tanks; discharge to POTW

Runway and taxiway runoff to infiltration system

Des Moines International Airport (DSM) Retained in storage tank; discharge to POTW

Hopkins International Airport (CLE) High strength to glycol recycling

Low strength to storage tanks; discharge to POTW

Washington Dulles International Airport (IAD) High strength to glycol recycling

Low strength to storage tank; discharge to POTW

Munich Airport (MUC) Runway runoff to basins; discharge to POTW

Taxiway runoff to on-site biodegradation treatment system

Stockholm-Arlanda Airport (ARN) Runway runoff drainage system to direct discharge

Greater Rockford Airport (RFD) Retained in aerated detention pond; direct discharge in

summer

Duluth International Airport (DLH) Retained in aerated retention pond; direct discharge

Albany International Airport (ALB) Retention ponds and storage tank to on-site anaerobic

fluidized bed reactor; discharge to POTW or land

application

Airborne Air Park (ILN) Drainage to on-site reciprocating aerobic/anaerobic

treatment system; direct discharge
Section 8.0 - Wastewater Characterization

8-1

8.0 WASTEWATER CHARACTERIZATION

As part of the characterization of airport deicing operations, EPA assessed what

constituents may be present in airport deicing/anti-icing fluid (ADF)-contaminated wastewater. 

Information presented in this section is based on data provided by the industry, EPA’s compliance

data, and EPA’s site visit and sampling programs. Section 8.1 presents industry self-monitoring

data; Section 8.2 presents data from EPA’s permit compliance system (PCS) database; Section

8.3 presents wastewater characterization data collected during EPA’s sampling program; and

Section 8.4 discusses multi-sector general permit application data. All tables appear at the end of

this section. Appendix A contains information regarding the location of airports referenced in this

section.

8.1 Industry Self-Monitoring Data

During the course of the study, EPA obtained storm water sampling data from five

airports. In general, these data represent discharges of ADF-contaminated wastewater; however,

some airports submitted data for nondeicing season discharges. Although the length of the

deicing season may vary among airports and also from year to year at a given airport, EPA

analyzed only data collected during the airport’s reported deicing season (e.g., October through

March). These data are described and summarized in this section.

EPA also received storm water monitoring data from Transport Canada and

Environment Canada for five Canadian airports. These data were collected as part of a study

designed to assess the effectiveness of the Canadian voluntary glycol guideline (discussed in

Section 13.3.1), to identify problems in wastewater management, and to develop better storm

water monitoring programs. These data are also described and summarized in this section.

In general, each airport monitored a unique set of parameters, which were

generally dictated by state and local permit requirements. In addition, some parameters can be

analyzed by multiple analytical methods, making it difficult to directly compare data submitted by
Section 8.0 - Wastewater Characterization

8-2

different airports. For example, glycols are analyzed by several different methods, the detection

limits of which vary from 1,000 mg/L to less than 1 mg/L. Therefore, a nondetect value at an

airport using an analytical method with a high detection limit may in fact have a higher glycol

concentration than a detected value at an airport using an analytical method with a low detection

limit. 

The data presented in this section generally represent discharges from the winter of

1997-1998 and/or the winter of 1998-1999, with some exceptions. EPA recognizes that some of

the pollutant discharge concentrations presented in this section may not represent current

pollutant discharges from the airports because several of the airports discussed in this section have

recently implemented pollutant control technologies (e.g., Milwaukee’s General Mitchell

International Airport). 

EPA recognizes that the data presented in this section may have several limitations. 

First, the data represent only a small subset of wastewater discharges from airport deicing/antiicing operations. Second, the data submitted by some airports were collected during only one

deicing season. Third, some of the data submitted by airports include samples collected on days

when no deicing/anti-icing operations were conducted. However, like the PCS data presented in

Section 8.2, EPA considers the effluent monitoring data a “snapshot” of pollutant discharges to

surface waters that may occur at airports. The data submitted by each airport are summarized

below.

Bradley International Airport, Windsor Locks, CT (BDL)

Bradley International Airport submitted analytical data for storm water outfall and

in-stream samples for the winters of 1990-1991, 1993-1994, 1996-1997, 1997-1998, and 1998-

1999. The outfall samples were collected from 13 different outfalls. The in-stream data were not

included in this summary because they do not represent ADF-contaminated wastewater

discharges. The discharge data summarized in Table 8-1 are presented by general location and

outfall. Some outfalls were sampled hourly for eight consecutive hours while a single grab sample
Section 8.0 - Wastewater Characterization

8-3

was collected at other outfalls. Outfall data are presented as either an average of hourly sampling

data or as the single grab sample result as applicable. As shown by the data in Table 8-1, most

ADF-contaminated wastewater discharges at BDL occur at Outfalls 2 and 3, which service the

passenger terminal and aircraft deicing pad areas.

Washington Dulles International Airport, Herndon, VA (IAD)

Washington Dulles International Airport submitted analytical data for samples

collected at the outfall from Horsepen Lake, a man-made impoundment located at the airport’s

northern property boundary. In general, the airport collected samples twice per day for 90 days

between December 1998 and April 1999. Sampling generally coincided with deicing operations;

however, EPA assumes, based on nondetect glycol values, that minimal deicing/anti-icing

occurred in April. The following data summarize the Horsepen Lake outfall data, excluding the

April 1999 data. 

Average Concentration (mg/L) Range (mg/L) Number of Data Points

Propylene Glycol <61.1 ND (5) - 986 124

Ethylene Glycol <5.52 ND (5) - 34 124

< - Maximum concentration.

ND - Not detected (followed by detection limit).

Logan International Airport, Boston, MA (BOS)

Logan International Airport submitted analytical data for storm water sampling

performed as part of its National Pollutant Discharge Elimination System (NPDES) storm water

permit application. The airport collected samples in March 1991, January 1992, and March 1992. 

The airport also collected samples in June 1991; however, these data are not included in this

summary because they do not represent storm water discharges during deicing operations. 

Although the data were collected from several years ago, EPA believes they represent current

deicing operation conditions at Logan.
Section 8.0 - Wastewater Characterization

8-4

Storm water runoff samples were collected and analyzed for several parameters,

including BOD5, ammonia, metals, ethylene glycol, and propylene glycol. Samples were collected

at the north and west outfalls, which directly drain to the adjacent harbor. The following data

summarize the results of storm water sampling during deicing events.

Date

North Outfall (mg/L) West Outfall (mg/L)

PG EG BOD5 Ammonia PG EG BOD5 Ammonia

3/15/91 120 110 8,320 2.3 240 95 5,500 2.9

1/23/92 ND (1) 1,100 592 5.3 130 280 531 3.8

3/19/92 <141 <641 N/A N/A <218 481 N/A N/A

Avg. <87.3 <617 4,456 3.8 <196 285 3,016 3.35

< - Maximum concentration.

PG - Propylene glycol.

EG - Ethylene glycol.

ND - Not detected (followed by the detection limit). 

N/A - Not available.

Baltimore/Washington International Airport, Baltimore, MD (BWI)

Baltimore/Washington International Airport performed a glycol mass balance study

using data collected during the 1997-1998 deicing season. The goal of the study was to

determine the percentage of glycol discharged relative to the volume of glycol sprayed on aircraft. 

The airport collected daily grab samples between October 24, 1997 and April 30, 1998 from two

watersheds that receive storm water discharges from the airport. The following table summarizes

the glycol and COD results for the Kitten Branch Watershed and Muddy Bridge Branch

Watershed.
Section 8.0 - Wastewater Characterization

8-5

1997-1998 Season Kitten Branch Watershed Muddy Bridge Branch Watershed

Average glycol concentration <10 <8.7

(mg/L)

Range of glycol concentrations ND (6) - 630 ND (6) - 30

(mg/L)

Range of COD concentrations ND (10) - 400 ND (10) - 690

Range of ammonia concentrations ND (1) ND (1) - 1.3

(mg/L)

Number of Data Points 159 159

< - Maximum concentration

ND - Not detected (followed by detection limit).

General Mitchell International Airport (MKE)

General Mitchell International Airport submitted analytical data from a study

conducted during the winter of 1996-1997. The purpose of the study was to assess the water

quality impacts that aircraft deicing fluids have on receiving streams. From November 1996

through April 1997, the airport conducted a monitoring program for flow, water quality

parameters (e.g., BOD5, glycols), and toxicity from 10 sampling stations, including two sampling

stations that directly measured runoff from the airport. The remaining sampling stations were

located in receiving streams both upstream or downstream of the airport. Because the other

sampling stations may not represent contaminated storm water discharges, only data for the two

airport sampling stations are summarized below. 

Outfall #1 Outfall #7

Average EG Concentration (mg/L) 170 123

Average PG Concentration (mg/L) 5,080 1,460

Average BOD5 Concentration (mg/L) 3,510 917

Number of Data Points 4 4

EG - Ethylene glycol.

PG - Propylene glycol.

The airport also conducted acute and chronic whole effluent toxicity (WET) tests

for both fathead minnows and Ceriodaphnia dubia for one sampling event on April 11, 1997. 
Section 8.0 - Wastewater Characterization

8-6

Data from this event were used to establish acute and chronic toxic criteria for the fathead

minnow and Ceriodaphnia dubia as follows:

Species Duration Aircraft Deicing/Anti-icing Fluid Concentration (mg/L)

Fathead minnow 96-hour LC50 1,650

7-day IC25 90

Ceriodaphnia dubia 48-hour LC50 3,150

7-day IC25 1,015

LC - Lethal concentration at which 50% of the test population dies. 50 

IC - Concentration at which 25% of the test organisms had inhibited growth, reproduction, or survival of the young. 25

Transport Canada/Environment Canada

Five Canadian airports were studied as part of the Transport Canada/Environment

Canada joint study of storm water monitoring at airports. For two of the airports, Quebec City

and Victoria, samples were collected at two outfalls. EPA believes the Canadian data are relevant

since some U.S. airports experience weather conditions that are similar to those experienced by

the Canadian airports. Note that Canada has a voluntary glycol guideline of 100 mg/L. The

following table summarizes the analytical data.

Airport (mg/L) 100 mg/L (mg/L) (mg/L)

Range of Total Glycol % of Samples Range of Ammonia Range of BOD

Concentration that Exceeded Concentration Concentration

5

St. John’s ND (1) - 120 1 ND (1) - 1.85 ND (1) - 89

Quebec City (A) ND (1) - 30,200 17.2 ND (0.03) - 197 ND (1) - 3,900

Quebec City (B) ND (1) - 2 0 ND (0.02) - 4.63 3 - 47

Thunder Bay ND (1) - 437 5.9 ND (0.03) - 106 ND (1) - 703

Victoria (A) ND (1) - 7 0 ND (0.03) - 27 ND (1) - 29

Victoria (B) ND (1) - 77 0 ND (0.03) - 11 ND (1) - 28

Halifax ND (5) - 130,000 28 ND (0.05) - 55 1 - 31

ND - Not detected (followed by detection limit).
Section 8.0 - Wastewater Characterization

8-7

Based on the data available to EPA, the range of glycol concentrations at these

Canadian airports is generally lower than those at U.S. airports presented in this section. This is

most likely a result of Canada’s voluntary guideline. The ammonia concentrations at Canadian

airports are significantly higher than those at the U.S. airports presented in this section. This is

most likely because the Canadian airports use urea as a pavement deicer, which many U.S.

airports are eliminating in favor of alternate pavement deicing agents.

8.2 Permit Compliance System (PCS)

EPA’s PCS database contains compliance, enforcement, and permitting

information for facilities that hold an NPDES permit. NPDES, which is authorized under Section

402 of the CWA, requires permits for the discharge of pollutants from any point source into

waters of the United States. 

The PCS database includes the following information for each facility included in

the database:

C Facility NPDES permit number;

C Facility name;

C Pipe number and description (i.e., code and description of each NPDESpermitted discharge point);

C Name and description of analyzed parameters;

C Average quantity and/or concentration limit (and maximum and minimum

limits, if applicable);

C Units of measurement for limits;

C Average quantity and/or concentration of parameter during monitoring

period (and maximum and minimum measurements, if applicable); and

C Units of measurement for monitoring parameters.
Section 8.0 - Wastewater Characterization

8-8

In 1998, EPA’s Office of Compliance extracted PCS records for Standard

Industrial Classification (SIC) code 4185 (Airports, Flying Fields, and Airport Terminal Services)

for the 1997-1998 deicing season (i.e., September through March) for EPA’s Office of Water. 

EPA recognizes that the pollutant discharge concentrations from this period may not represent

current industry pollutant discharges because several airports have recently implemented

contaminated storm water collection and/or treatment techniques and/or POTW discharge that

would not be reflected in the 1997-1998 data. 

The PCS database excerpt for SIC code 4185 contained information for 42

different airports from across the U.S. However, some of these airports are small or general

aviation airports or are in southern locations, where few deicing operations are expected to occur. 

EPA compared the airports in the PCS database to the list of airports thought to have potentially

significant deicing/anti-icing activities (see discussion in Section 4.3.1) and determined that 14 of

the airports in the PCS database were on this list. 

Using information in the PCS database for the 14 airports, EPA evaluated each

permitted outfall and types of parameters to determine whether the outfall discharges wastewater

containing deicing/anti-icing chemicals. For example, if an airport is required to collect and

analyze storm water for glycol at a particular outfall, then EPA considered the outfall as

discharging wastewater containing deicing/anti-icing chemicals. In contrast, if an airport is

required to analyze only for oil and grease and volatile organic pollutants at a particular outfall,

then EPA considered the outfall as not discharging wastewater containing deicing/anti-icing

chemicals and eliminated it from further analyses. 

After EPA edited the database using the above criteria, information from 10

airports remained in the database. These airports include:

C Chicago O’Hare International (ORD);

C Louisville International - Standiford Field (SDF);

C Baltimore/Washington International (BWI);

C Minneapolis-St. Paul International (MSP);
Section 8.0 - Wastewater Characterization

8-9

C Newark International (EWR);

C Westchester County (HPN);

C Tompkins County (ITH);

C Syracuse Hancock International (SYR);

C Nashville International (BNA); and

C Salt Lake City International (SLC).

Table 8-2 summarizes effluent monitoring data for direct discharges for these airports, grouped by

discharge location and/or similar discharge characteristics (e.g., runway or terminal outfalls).

It is important to recognize that the data presented in Table 8-2 have certain

limitations, such as: 1) EPA was not able to verify for all airports that the outfalls presented in

Table 8-2 are representative of wastewater discharges containing deicing/anti-icing chemicals, 2)

the data represent only a small subset of wastewater discharges from airport deicing/anti-icing

operations, 3) the data were collected during only one deicing season (the winter of 1997-1998),

and 4) the data may not represent current deicing/anti-icing operations at these airports. 

However, EPA considers the effluent monitoring data a “snapshot” of pollutant discharges to

surface waters that may occur at airports.

8.3 EPA Sampling Data

To supplement the analytical data available from the industry, EPA undertook a

sampling program consisting of six sampling episodes. The goals of the sampling program were

to: (1) identify pollutants present in wastewater from aircraft deicing and anti-icing operations; (2)

determine the possible range of concentrations for each pollutant identified; and (3) assess the

effectiveness of different wastewater treatment methods currently used at U.S. airports. To

achieve these goals, EPA collected the following samples:

C Ethylene glycol-based aircraft deicing fluid (i.e., a Type I fluid);

C Propylene glycol-based aircraft deicing fluid (i.e., a Type I fluid); 
Section 8.0 - Wastewater Characterization

8-10

C Influent to and effluent from an anaerobic biological treatment system used

to treat ADF-contaminated wastewater at Albany International Airport;

C Wastewater discharge to a POTW from a retention basin used to collect

ADF-contaminated wastewater at Kansas City International Airport;

C Influent to and effluent from a reverse osmosis system at Bradley

International Airport used to recover glycol from low-strength ADFcontaminated wastewater for further processing; 

C Storm water outfall which drains aircraft deicing/anti-icing areas at Bradley

International Airport (sample collected during the deicing season, but not

concurrent with a deicing event); and

C Influent to and effluent from an aerobic biological treatment system used to

treat ADF-contaminated wastewater at Greater Rockford Airport.

These samples were analyzed for a large number of conventional and nonconventional pollutants

and, in a few cases, for whole effluent toxicity. Table 8-3 lists the classes of pollutants analyzed

as well as the analytical methods used. 

The analytical data for the wastewater recovery and treatment systems, including

an assessment of their efficiency, is presented in Section 6.4.1 for Bradley International Airport

and Section 7.2.1. for Albany International Airport and Greater Rockford Airport. This section

presents the analytical results for the two Type I fluids (Section 8.3.1) and for several raw

wastewater samples and one storm water outfall sample (Section 8.3.2). Section 8.3.3 discusses

the analytical results.

8.3.1 Type I Aircraft Deicing Fluids

Based on data provided by the industry, EPA estimates that more than 90% by

volume of all ADF fluids sprayed in a given deicing season are Type I, with Type IV fluids

comprising most of the remaining 5% to 10% and Type II fluids being largely obsolete. Since

Type I fluids are used in much greater quantities than Type II and Type IV fluids, EPA analyzed

samples of two Type I formulations as control or background samples for the sampling program. 
Section 8.0 - Wastewater Characterization

8-11

There are currently three principle manufacturers/formulators of Type I fluids in

the U.S.: Union Carbide, Lyondell (formerly ARCO), and Octagon Process. Union Carbide’s

Type I fluids contain ethylene glycol as the freezing point depressant, while those of Lyondell and

Octagon contain propylene glycol. In recent years, the mammalian toxicity of ethylene glycol,

combined with the Comprehensive Environmental Response, Compensation, and Liability Act

(CERCLA) reporting requirements (see Section 13.2.1) and the proliferation of propylene glycol

recovery, have made propylene glycol-based fluids dominant in the U.S. However, some carriers

continue to use ethylene glycol-based products, and, at a few U.S. airports, the volume of

ethylene glycol-based fluid applied to aircraft exceeds that of propylene glycol-based fluid. 

Consequently, EPA decided to analyze both an ethylene glycol-based Type I fluid (trade name

UCAR Aircraft Deicing Fluid Concentrate, Union Carbide) and a propylene glycol-based Type I TM 

fluid (trade name Octaflo Concentrate, Octagon Process). TM

The samples were collected directly into sample containers and shipped to EPA

contract laboratories for analysis. Chemical preservation was not required for these samples,

although they were shipped on ice to maintain a sample temperature of 4E C. The samples were

diluted with reagent grade water to a 50% solution prior to analysis to represent fluid as applied

to aircraft. EPA recognizes that airlines sometimes dilute Type I fluid concentrate to solutions

containing less than 50% ADF, but believes the 50% dilution is most typical of industry practices. 

 The samples were analyzed for volatile organics, semivolatile organics (including

tolyltriazoles), metals, total organic carbon (TOC), and ammonia as nitrogen. Table 8-4 lists

analytes detected in the diluted samples as well as their concentrations. EPA did not analyze the

ADF samples for glycols, biochemical oxygen demand, or acute toxicity. Some of this

information is available from fluid formulators, who collect environmental data both to comply

with Society of Automotive Engineers’ fluid certification reporting requirements (see Section

13.5) and to assist customers with waste management issues. Table 8-5 summarizes the data

provided by the fluid manufacturers/formulators.
Section 8.0 - Wastewater Characterization

8-12

Table 8-4 should not be viewed as a comprehensive list of all pollutants present in

wastewater from aircraft deicing/anti-icing operations. The fluids are known to contain a variety

of additives, including wetting agents, fire suppressants, and potentially toxic corrosion inhibitors,

many of which could not be included on the list of analytes because their identity was unknown

and is considered proprietary by the fluid manufacturers.

8.3.2 Characterization of Wastewater from Aircraft Deicing/Anti-icing Operations

To characterize raw wastewater from aircraft deicing/anti-icing operations, EPA

collected samples from a variety of airport wastewater storage facilities. These samples included

wastewater from a portable storage tank at Bradley International Airport, an uncovered concrete

basin at Kansas City International Airport, a storage tank and two detention ponds at Albany

International Airport, and an aerated detention pond at Greater Rockford Airport. EPA also

collected one storm water outfall sample at Bradley International Airport to characterize direct

discharge of ADF-contaminated storm water. Sample fractions were preserved as specified by the

analytical methods, packed in ice, and shipped overnight to EPA contract laboratories for analysis. 

All samples were analyzed for semivolatile organics (including tolyltriazoles), glycols, metals

(including potassium), TOC, ammonia as nitrogen, BOD , hexane extractable material (HEM), 5

and silica-gel hexane extractable material (SGT-HEM). Whole effluent toxicity (WET) tests were

performed on samples collected at Kansas City International Airport and Bradley International

Airport. The sample from Albany International Airport was also analyzed for volatile organic

compounds. 

Each sampling point and the sample collection method are briefly described below. 

Table 8-4 lists the analytes detected in the wastewater samples as well as their concentrations.

Albany International Airport, Albany, NY (ALB)

Aircraft deicing/anti-icing at Albany International Airport is performed using only

propylene glycol-based fluids, and is permitted only in designated areas where a drainage
Section 8.0 - Wastewater Characterization

8-13

collection system consisting of graded pavement surfaces, catch basins, trench drains, and wet

wells are installed. Wastewater collected in the wet wells is pumped through force mains to the

airport’s wastewater storage area, which consists of a 6-million-gallon lagoon, a 2.3-milliongallon lagoon, and a 2.5-million-gallon above-ground tank. The lagoons are equipped with piping

systems and blowers to provide gross diffusion aeration and a recirculation pump to move

wastewater from the pond center to the edge. The primary purpose of the aeration and

recirculation systems is to reduce glycol stratification within the lagoons. On March 24, 1999, 

EPA collected a grab sample of wastewater from the small lagoon and a composite sample from

the storage tank and large lagoon. Grab samples were also collected from the large lagoon and

the storage tank for analysis of HEM and SGT/HEM. EPA also analyzed a sample of effluent

from the treatment system. The analytical data for the effluent sample of is provided in Section

7.2.1.

Kansas City International Airport, Kansas City, KS (KCI)

At Kansas City International Airport, airlines and fixed-base operators use either

ethylene glycol- or propylene glycol-based fluids for aircraft deicing/anti-icing. Wastewater from

aircraft deicing and anti-icing operations are collected at the passenger terminal using a trench

drain system specifically designed for this purpose. The wastewater, combined with any storm

water runoff, enters the trench drains and is conveyed by underground pipes to a concrete storage

basin. The storage basin consists of two 1-million-gallon cells: the west cell and the east cell. 

The storage cells are operated in parallel, with one filling while the other is discharging to a local

POTW. Because the storage cells are uncovered, rain water dilutes the wastewater and sunlight

helps to degrade the glycols present. EPA collected a grab sample of wastewater from the west

cell on February 25, 1999. The cell was approximately half-full at the time of sampling and had

received wastewater from aircraft deicing/anti-icing operations since February 15, 1999. 
Section 8.0 - Wastewater Characterization

8-14

Bradley International Airport, Windsor Locks, CT (BDL)

At Bradley International Airport, aircraft deicing and anti-icing operations are

performed using propylene glycol-based fluids and are conducted on the airport’s aircraft deicing

pad, at the passenger terminal, and on the cargo ramps. Wastewater is collected at the passenger

terminal and cargo ramps using vacuum trucks, while wastewater generated at the deicing pad

drains into a sump. The collected wastewater is transferred to several 20,000-gallon temporary

storage tanks located at the airport’s glycol recycling facility (discussed in Section 6.4.1). The

wastewater is segregated based on the glycol concentration, which typically varies between 1%

and 30% (i.e., between 10,000 mg/L and 300,000 mg/L), depending on the volume of fluid used

and the type of precipitation. EPA collected a wastewater grab sample from one of the temporary

storage tanks on March 9, 1999. EPA also analyzed a sample of effluent from the treatment

system. The analytical data for the effluent sample are provided in Section 6.4.1.

Storm water from the southern areas of the airfield, including the passenger

terminal areas and the remote deicing pad (with the exception of that collected as described

above), flows to Outfalls 3-1 and 3-2. On March 9, 1999, EPA collected a grab sample of the

combined outfalls from an above-ground channel at a point down stream from the outfalls where

the two streams combine. Although the sample was collected during the deicing season, it was

not collected concurrent with a deicing event.

Greater Rockford Airport, Rockford, IL (RFD)

Aircraft deicing/anti-icing operations are performed at the airport’s deicing pad

and on a ramp at the cargo facility, where wastewater collection systems have been installed. 

Although the airport authority allows its tenants to use either propylene glycol- or ethylene

glycol-based fluids, most of the fluid used at the airport is ethylene glycol-based. The wastewater

collected at the airport’s deicing pad and the cargo facility is conveyed via underground pipes and

a diversion box to a 16-million-gallon aerated detention pond, where aerobic biological treatment

takes place. Wastewater collected during the deicing season is retained in the detention pond
Section 8.0 - Wastewater Characterization

8-15

until midsummer, when the treated fluid is discharged to a nearby river. The rate of

biodegradation is dependent on temperature; biodegradation occurs primarily in spring and

summer months when ambient temperatures are above 40E F. 

EPA collected a grab sample of wastewater from the detention pond on April 14,

1999, following the close of the deicing season. During the three weeks immediately preceding

the sampling episode, ambient temperatures were unseasonably warm, with daily highs reaching

above 70E F on five separate days. A review of analytical data provided by the airport indicates

that some treatment had already occurred prior to the sampling episode. This conclusion is

further supported by EPA’s data, which show that glycols, known to biodegrade rapidly, were not

detected in the wastewater sample. Consequently, the sample is not representative of raw

wastewater from airport deicing/anti-icing operations, at least with respect to glycol levels. EPA

also analyzed a sample of effluent from the treatment system. The analytical data for the effluent

sample of is provided in Section 7.2.1.

8.3.3 Discussion of Sampling Results

Analytical results for the Type I fluids show that the composition of Type I fluids

varies considerably. For example, three volatile organic compounds (ethylbenzene, toluene, and

m- + p-xylene) and three metals (antimony, manganese, and thallium) were detected in the

propylene glycol-based fluid, but were not detected in the ethylene glycol-based fluid. Similarly,

two semivolatile compounds (di-n-butyl phthalate and n-dodecane) and one metal (chromium)

were detected in the ethylene glycol-based fluid, but not in the propylene glycol-based fluid. 

The concentrations of the analytes that were detected in both fluids also differed. 

The ethylene glycol-based fluid contained higher concentrations of bis(2-ethylhexyl) phthalate,

aluminum, boron, cadmium, and sodium, while the propylene glycol-based fluid contained higher

concentrations of 5-methyl-1H-benzotriazole, arsenic, barium, calcium, copper, iron, lead, tin,

zinc, and ammonia. Pollutant concentrations that differed by more than an order of magnitude
Section 8.0 - Wastewater Characterization

8-16

include those for bis(ethylhexyl) phthalate, 5-methyl-1H-benzotriazole, arsenic, boron, cadmium,

and thallium.

In general, pollutants detected in the Type I fluids were also detected in the raw

wastewater samples. However, a number of analytes were detected in at least one of the Type I

fluids, but were not detected in any of the raw wastewater samples. These analytes include

ethylbenzene, toluene, m- + p-xylene, di-n-butyl phthalate, n-dodecane, antimony, boron,

selenium, and thallium. There are several possible reasons for these results. First, wastewater

from aircraft deicing/anti-icing operations is typically diluted by storm water, which may mask the

presence of these pollutants. Second, the Type I fluids analyzed for this study may not have been

used at the airports that were sampled. Third, biological activity in the storage units may have

degraded some pollutants.

Several analytes were detected in at least one of the raw wastewater samples but

not in either of the Type I fluids analyzed. These analytes include n-hexadecane, phenol, ntetradecane, magnesium, silver, titanium, and vanadium. Other analytes were detected in both

Type I fluids and in all raw wastewater samples; however, the concentration of the analyte was

generally greater in the raw wastewater samples. These analytes include aluminum, barium,

calcium, iron, sodium, and ammonia as nitrogen. There are several possible sources of these

pollutants. First, they may be constituents of anti-icing fluids (i.e., Type II and Type IV fluids) or

other Type I formulations. Second, they may be present in the water used at the airport to dilute

the Type I fluid concentrate. Third, they may be present in precipitation. Fourth, they may be

constituents present in pavement deicing/anti-icing agents. Fifth, they may be pollutants rinsed

from aircraft or pavement surfaces during aircraft deicing operations. Pollutants were generally

detected in higher concentrations in the raw wastewater sample collected at Bradley International

Airport because the airport purposely attempts to collect wastewater with the highest possible

ADF concentration for processing through its on-site glycol recycling system.

Although pavement deicing/anti-icing was not the primary focus of the sampling

program, EPA included ammonia as nitrogen, potassium, magnesium, sodium, and calcium on the
Section 8.0 - Wastewater Characterization

8-17

list of analytes measured in raw wastewater samples. Ammonia is a common degradation product

of urea (a solid pavement deicer), while potassium acetate, calcium magnesium acetate, sodium

acetate, and sodium formate (common pavement deicer/anti-icers) are potential significant

sources of the remaining pollutants. 

Ammonia concentrations in the raw wastewater samples ranged from 3.9 mg/L to

88 mg/L. Ammonia concentrations greater than 5 mg/L are known to be toxic to aquatic

organisms, including the test species used in the whole effluent toxicity tests. The highest

ammonia concentrations were found in wastewater samples collected at Albany International

Airport, which reported using urea for deicing a newly constructed apron near the passenger

terminal. Urea was used on this apron during the 1998-1999 winter, because application of

potassium acetate (i.e., the pavement deicing/anti-icing typically used at Albany) would have

voided the manufacturer’s one-year warranty on the apron construction. Bradley International

Airport and Greater Rockford Airport both reported using urea for runway and taxiway deicing. 

Note that the ammonia concentration in the storm water outfall from Bradley International

Airport, 1.1 mg/L, was significantly less than 5 mg/L.

Concentrations of potassium in the raw wastewater samples varied considerably. 

The highest concentrations were detected in wastewater samples collected at Albany International

Airport and Greater Rockford Airport, where potassium levels were approximately 60,000 Fg/L.

All of the airports sampled reported using potassium acetate on airfield pavements, mostly applied

to runways and taxiways. None of the airports sampled reported using sodium acetate, calcium

magnesium acetate, or sodium formate for airfield deicing/anti-icing.

In general, pollutants detected in the raw wastewater sample from Bradley

International Airport were also detected in the storm water outfall. However, many pollutants

detected in the outfall were not detected in the raw wastewater sample, likely because the outfall

is diluted by storm water from non-deicing areas. Two pollutants, antimony and boron, were

detected in the outfall but not in the raw wastewater. These pollutants may be contributed by

natural sources.
Section 8.0 - Wastewater Characterization

8-18

8.4 Multi-Sector General Permit Application Data

As described in Section 13.1.3, Part 2 of the Multi-Sector General Permit

application includes quantitative data based on samples collected during storm events from

outfalls containing storm water discharges associated with industrial activity. The American

Association of Airport Executives submitted a group permit application on behalf of 700 airports. 

Part 2 of the application included sampling data for 59 airports considered to be representative of

the group. Sampling parameters included oil and grease, pH, BOD , COD, total suspended solids 5

(TSS), total phosphorus, total Kjeldahl nitrogen, and nitrate plus nitrite nitrogen. Data from only

one airport are relevant to airport deicing operations. The remaining data were collected during

summer rain events when potential sources of pollutants consisted of aircraft fueling, cleaning,

and maintenance. 
Section 8.0 - Wastewater Characterization

8-19

Table 8-1

Summary of Storm Water Monitoring Data from 

Bradley International Airport

Group Location Date (mg/L) (mg/L) (mg/L) (mg/L)

Average BOD Ammonia Glycol Propylene Glycol

Concentration Concentration Concentration Concentration

Average Ethylene Average

Average

Southeast Outfall 1A 2/14/91 28 2.6 11.2 NA

drainage 2/27/91 560 6.1 43.8 NA

3/13/91 11 0.33 0.12 NA

3/4/97 30 0.36 ND (10) ND (10) 

3/14/98 NA NA ND (50) ND (50)

2/2/99 76 2.7 ND (10) ND (10)

3/15/99 >190 0.87 ND (10) ND (10)

Outfall 1B 2/14/91 31 2.5 10.4 NA

2/27/91 520 6.1 20.8 NA

3/13/91 3 0.11 ND (0.1) NA

3/14/98 NA NA ND (50) ND (50)

Outfall 14 3/14/98 NA NA ND (50) ND (50)

Terminal Outfall 2 2/14/91 8,300 2.3 11,700 ND (500)

drainage 2/27/91 6,700 1.9 6,600 ND (50)

(South) 3/13/91 32 0.24 10.5 ND (10)

1/28/94 NA <1.8 <150 17,000

3/9/94 NA 3.1 <103 370

3/4/97 69 0.61 40 9.1

3/14/98 NA NA ND (50) ND (50)

2/2/99 >87 21 ND (10) <280

3/15/99 50 2.2 ND (10) <29

Outfall 2/14/91 22,000 4.6 22,500 13,000

3-1 2/27/91 3,200 3.7 24,000 12,000

3/13/91 2 0.32 0.29 ND (10)

1/28/94 NA <0.7 ND (100) 17,000

3/9/94 NA 3.2 <99 11,000

3/4/97 >304 1.13 ND (10) 700

3/14/98 NA NA ND (100) 250

2/2/99 >94 12 ND (10) 1,400

3/15/99 >190 1.6 <1,700 <340

Outfall 3/14/98 NA NA ND (1,000) 3,600

3-2 2/2/99 >94 29 ND (10) 1,200

3/15/99 >190 3.8 ND (10) 180
Table 8-1 (Continued)

Section 8.0 - Wastewater Characterization

Group Location Date (mg/L) (mg/L) (mg/L) (mg/L)

Average BOD Ammonia Glycol Propylene Glycol

Concentration Concentration Concentration Concentration

Average Ethylene Average

Average

8-20

West Outfall 5 3/14/91 6 1.2 1.9 NA

drainage 2/27/91 ND (2) 0.18 ND (0.1) NA

3/13/91 ND (2) 0.22 ND (0.1) NA

3/4/97 5.6 0.76 ND (10) ND (10)

Outfall 7 2/2/99 ND (2) 0.22 ND (10) ND (10)

3/15/99 ND (15) 0.14 ND (10) ND (10)

Outfall 8 2/2/99 10 7.7 ND (10) ND (10)

3/15/99 ND (15) 0.71 ND (10) ND (10)

Outfall 9 3/4/97 1.2 0.16 ND (10) ND (10)

3/14/98 NA NA ND (50) ND (50)

2/2/99 ND (2) 1.5 ND (10) ND (10)

3/15/99 ND (15) 0.33 ND (10) ND (10)

Outfall 10 2/14/91 ND (2) 1.2 ND (0.1) NA

2/27/91 ND (2) 0.92 ND (0.1) NA

3/13/91 2 0.75 ND (0.1) NA

3/14/98 NA NA ND (50) ND (50)

2/2/99 ND (2) 0.65 ND (10) ND (10)

3/15/99 ND (15) 0.53 ND (10) ND (10)

Northeast Outfall 2/14/91 8 0.54 1.7 NA

drainage 13-1 2/27/91 ND (2) 0.23 ND (0.1) NA

3/13/91 ND (2) 0.2 ND (0.1) NA

3/4/97 7.8 19.6 ND (10) ND (10)

3/14/98 NA NA ND (50) ND (50)

2/2/99 7.6 0.46 ND (10) ND (10)

3/15/99 >190 1.1 ND (10) 2,100

Outfall 2/14/91 2 0.47 ND (0.1) NA

13-2 2/27/91 ND (2) 0.13 ND (0.1) NA

3/13/91 2 0.51 0.17 NA

3/14/98 NA NA ND (50) ND (50)

> - Minimum concentration.

< - Maximum concentration.

NA - Not available.

ND - Not detected (followed by detection limit).
Section 8.0 - Wastewater Characterization

8-21

Table 8-2

Summary of PCS Data for Airports with EPA-Estimated Potentially

Significant Deicing/Anti-Icing Operations

Airport Discharge Point(s) Parameter Effluent(a) Points Points

Average Range of Data # of Data

Chicago 0110, 0210, 0310, BOD (mg/L) 111 1.1 - 1,650 36

O’Hare 0410, 0610, 0810, pH (S.U.) NA 6.9 - 7.6 36

International 081A - Storm water NH - N (mg/L) 10.8 0.2 - 50 36

(ORD) (NW drainage) TDS (mg/L) 1,080 232 - 3,370 36

5

3

0910, 1010, 1110, BOD (mg/L) 134 1 - 2,150 34

1120, 1130, 1140 - pH (S.U.) NA 6.0 - 7.6 34

Storm water (N NH - N (mg/L) 11.2 0.2 - 50 34

drainage) TDS (mg/L) 645 227 - 1,620 34

5

3

1210 - Storm water BOD (mg/L) 40.2 2.5 - 141 6

(NE drainage) pH (S.U.) NA 6.9 - 7.5 6

5

NH3 - N (mg/L) 3.4 0.6 - 10 6

TDS (mg/L) 1,200 105 - 2,080 6

1410 - Storm water BOD (mg/L) 117 9.2 - 342 6

(SE drainage) pH (S.U.) NA 6.7 - 7.6 6

5

NH3 - N (mg/L) 35.1 2.6 - 85 6

TDS (mg/L) 1,050 624 - 1,340 6

3720, 3730, 4710 - BOD (mg/L) 291 0.9 - 3,100 17

Storm water (SW pH (S.U.) NA 6.8 - 7.6 17

drainage) NH - N (mg/L) 8.28 0.7 - 37.5 17

5

3

TDS (mg/L) 1,740 211 - 8,470 17

091A, 091B - BOD (mg/L) 381 264 - 497 2

drainage from pH (S.U.) NA 7.3 2

deicing activities NH - N (mg/L) 50 50 2

5

3

TDS (mg/L) 727 616 - 837 2

Louisville 011, 021, 031, 041, Benzene (ug/L) <7.62 <5 - 97 27

International - 061 - Storm water/ BOD (mg/L) 77.7 3 - 1,250 27

Standiford deicing fluid runoff Ethylbenzene (ug/L) <8.48 <5 - 127 27

Field Naphthalene (ug/L) <15.2 <5 - 361 27

(SDF) NH - N (mg/L) <17.2 <0.03 - 171 27

5

3

Oil and grease (mg/L) <1.27 <1 - 3.5 27

DO (mg/L) 7.9 0.270 - 13.0 27

pH (S.U.) NA 7.0 - 9.1 27

TSS (mg/L) 473 2.00 - 3,530 27

Toluene (ug/L) <5 <5 27

Xylene (ug/L) <5 <5 27
Table 8-2 (Continued)

Section 8.0 - Wastewater Characterization

Airport Discharge Point(s) Parameter Effluent(a) Points Points

Average Range of Data # of Data

8-22

Baltimore/ 306A and 307A - BOD (mg/L) 1,010 23 - 2,510 4

Washington Outfall 003 (runway, EG (mg/L) <10 <10 4

International terminal, and deicing TKN (mg/L) 12.8 2 - 27 4

(BWI) pad drainage) pH (S.U.) NA 6.7 - 7.5 4

5

007A and 703A - BOD (mg/L) 412 197 - 769 4

Storm water runoff EG (mg/L) <10 <10 4

(from taxiway, Petroleum

terminal, and ramps) Hydrocarbons (mg/L) 1 1 1

5

TKN (mg/L) 2.25 2 - 3 4

pH (S.U.) NA 6.7 - 7.1 4

Minneapolis- 010M and 01AM - BOD (tons/mo) 0.1 <0.001 - 0.5 10

St. Paul Mother Lake and BOD (mg/L) 90.9 1 - 694 10

International Duck Lake drainage BOD (mg/L) 5.50 2 -10.0 4

(MSP) (runways and PG (mg/L) 137 9.4 - 596 5

taxiways) EG (mg/L) 14.4 4.1 - 32.6 3

5

5

40

COD (mg/L) 243 6 - 1,880 10

NH3 - N (mg/L) 11.5 0.09 - 50.6 10

NH3 (mg/L) 0.638 0.002 - 5.27 10

TKN (mg/L) 20.2 0.3 - 75 9

Oil and grease (mg/L) 2.28 0.8 - 7.7 7

DO (mg/L) 7.02 1.8 - 9.7 10

pH (S.U.) NA 7.1 - 8.5 10

P (mg/L) 0.329 0.07 - 0.83 8

TSS (mg/L) 15.3 2 - 76 10

Toluene (mg/L) 0.002 0.002 1

020M, 030M, BOD (tons/mo) 14 0.1 - 83 18

03AM - Minnesota BOD (mg/L) 497 5 - 2,140 18

River North and BOD (mg/L) 319 8 - 676 12

Snelling Lake PG (mg/L) 313 3.2 - 1,660 14

drainage (terminal, EG (mg/L) 95.8 2.6 - 561 10

runway, and taxiway COD (mg/L) 763 2.9 - 4,320 18

drainage) NH - N (mg/L) 19.4 0.48 - 124 18

5

5

40

3

NH3 (mg/L) 0.671 0.02 - 10.7 18

TKN (mg/L) 48.4 1.3 - 290 18

Oil and grease (mg/L) 3.90 1.2 - 9.6 17

DO (mg/L) 4.82 0.9 - 9.6 18

pH (S.U.) NA 6.8 - 8.1 18

P (mg/L) 0.114 0.01 - 0.41 16

TSS (mg/L) 15.6 5 - 54 18

Benzene (ug/L) 4.7 0.1 - 12 4

Ethylbenzene (ug/L) 2.7 0.2 - 5 4

Toluene (ug/L) 6.2 0.2 - 23 6

Xylene (ug/L) 16.3 3 - 30 4
Table 8-2 (Continued)

Section 8.0 - Wastewater Characterization

Airport Discharge Point(s) Parameter Effluent(a) Points Points

Average Range of Data # of Data

8-23

Minneapolis- 040M - Minnesota BOD (tons/mo) 10 0.001 - 41 6

St. Paul River South drainage BOD (mg/L) 641 5 - 1,210 6

International area (terminal and BOD (mg/L) 26.0 18 - 34 2

(cont.) cargo areas) PG (mg/L) 853 137 - 1,830 4

5

5

40

EG (mg/L) 27.9 1.7 - 54.2 4

COD (mg/L) 1,250 37 - 3,170 6

NH3 - N (mg/L) 44.2 0.04 - 172 6

NH3 (mg/L) 8.18 0.003 - 42.7 6

TKN (mg/L) 77.5 1 - 235 6

Oil and grease (mg/L) 15.8 2.8 - 67 6

DO (mg/L) 4.72 1.9 - 7.6 6

pH (S.U.) NA 8.2 - 8.7 6

P (mg/L) 0.378 0.18 - 0.73 6

TSS (mg/L) 32.8 10 - 67 6

Benzene (ug/L) 0.45 0.3 - 0.6 2

Ethylbenzene (ug/L) 1.7 1.7 1

Toluene(ug/L) 18 1.8 - 34.6 2

Xylene (ug/L) 1.2 1.2 1

Newark 006A - Storm water TOC (mg/L) 16 9 - 23 7

International from terminal Hydrocarbons (mg/L) 2.45 1 - 3.9 7

(EWR) pH (S.U.) NA 6.1 - 7.0 7

TSS (mg/L) 11.3 3 - 38 7

008A, 009A, 013A, TOC (mg/L) 83.5 7 - 1,120 32

014A, 014B, 015A - COD (mg/L) 189 49 - 338 7

Storm water from Hydrocarbons (mg/L) <1.98 <0.4 - 8.8 39

runway pH (S.U.) NA 5.1 - 7.5 39

TSS (mg/L) <12.5 <2 - 64 39

Westchester 001A and 003A - BOD (mg/L) 2.82 2 - 7.2 14

County Storm water from PG (mg/L) 32.8 0.05 - 220 12

(HPN) ponds Oil and grease (mg/L) 5 5 14

5

pH (S.U.) NA 6.9 - 8.6 14

004A, 008A, 009A - BOD (mg/L) 4.92 2 - 37 21

Storm water from PG (mg/L) 0.134 0.05 - 0.82 18

buildings and Oil and grease (mg/L) 5 5 21

hangars pH (S.U.) NA 6.3 - 8.8 21

5

005A, 006A, 007A - BOD (mg/L) 2.53 2 - 8.4 19

Storm water from PG (mg/L) 0.213 0.05 - 1.3 17

taxiways and ditch Oil and grease (mg/L) 5 5 19

drainage pH (S.U.) NA 6.0 - 8.0 19

5

Tompkins 001M, 004M, 005M BOD (mg/L) <3 <3 - 3 18

County - Storm water runoff

(ITH)

5

002M - Storm water Oil and grease (mg/L) <0.5 <0.5 - 0.5 7

from deicing/fueling pH (S.U.) NA 6.8 - 7.5 7

pad
Table 8-2 (Continued)

Section 8.0 - Wastewater Characterization

Airport Discharge Point(s) Parameter Effluent(a) Points Points

Average Range of Data # of Data

8-24

Syracuse 001M, 003M, BOD (mg/L) <334 <4 - 3,500 30

Hancock 004M, 005M, Oil and grease (mg/L) <6.18 <4 - 26 36

International 006M, 007M - pH (S.U.) NA 6.8 - 8.2 36

(SYR) Storm water runoff TSS (mg/L) <11.5 <4 - 19 6

5

NH3 - N (mg/L) 7.3 0.17 - 24.3 14

Benzene (ug/L) <2.5 <1 - <5 12

Nashville 002G - Effluent from BOD (mg/L) 38.1 3 - 98 7

International treatment basin HEM (mg/L) <6.71 <1 - 14 7

(BNA) COD (mg/L) <69.6 <20 - 130 7

5

DO (mg/L) 8.64 6.4 - 11.9 7

pH (S.U.) NA 7.2 - 8.6 7

TSS (mg/L) 32.7 18 - 55 7

Salt Lake City 001A, 002A, 003A - BOD (mg/L) 332 11 - 1,050 11

International Storm water Nitrate/Nitrite (mg/L) 4.73 0.9 - 9 5

(SLC) discharge from Oil and grease (mg/L) 9 8 - 10 2

terminal, runway, COD (mg/L) 835 104 - 3,880 12

apron, and cargo pH (S.U.) NA 6.6 - 9.5 21

areas

5

(a) Data represent only the 1997-1998 Deicing Season.

Key: BOD - 5-day biochemical oxygen demand. 5

BOD - 40-day biochemical oxygen demand. 40

COD - Chemical oxygen demand.

DO - Dissolved oxygen.

EG - Ethylene glycol.

HEM - Hexane extractable material (i.e., oil and grease).

NA - Not applicable.

NH - Ammonia - un-ionized. 3

NH -N - Ammonia as Nitrogen. 3

P - Phosphorus.

PG - Propylene glycol.

TDS - Total dissolved solids.

TKN - Total kjeldahl nitrogen.

TSS - Total suspended solids.

< - Not detected or maximum concentration.
Section 8.0 - Wastewater Characterization

8-25

Table 8-3

Standard Analytical Methods for Parameters Included in EPA’s 

Airport Deicing Sampling Program

Parameter Method Number

Ammonia as nitrogen 350.2

Biochemical oxygen demand (5-day) 405.1

Total organic carbon 415.1

Glycols 624

Metals (including potassium) 1620

Volatile organic compounds 1624C

Semivolatile organic compounds (including 1625C

tolyltriazoles)

Hexane extractable material 1664

Silica-gel treated hexane extractable material 1664

Whole effluent toxicity: NA

 Fathead Minnow (Pimephales promelas)

 Cladoceran (Ceriodaphnia dubia)

NA - Method number not applicable. Analytical methods per Methods for Measuring the Acute Toxicity of Effluents

and Receiving Water to Fresh Water and Marine Organisms, U.S. EPA, August 1993.
Section 8.0 - Wastewater Characterization

ND - Analyte not detected (followed by detection limit).

NA - Not analyzed.

> - Minimum concentration.

8-26

Table 8-4

Analytical Results for Analytes Detected in Type I Aircraft Deicing Fluids (50% Solution), Raw Wastewater

from Airport Deicing/Anti-Icing Operations, and a Stormwater Outfall

EPA Sampling Data

Priority Ethylene Propylene Composite of Kansas City Bradley Greater Bradley

Pollutant Glycol- Glycol- Small Large Lagoon International International Rockford International

Code Analyte Based Fluid Based Fluid Lagoon and Tank Airport Airport Airport Airport

Type I Deicing Fluids

(50% Solution) Albany International Airport

Raw Wastewater Samples Samples

Storm Water

Outfall

VOLATILE ORGANICS (Fg/L)

P038 ETHYLBENZENE ND(100) 580 ND(10) NA NA NA NA NA

P086 TOLUENE ND(100) 620 ND(10) NA NA NA NA NA

M- + P-XYLENE ND(100) 2,800 ND(10) NA NA NA NA NA

SEMIVOLATILE ORGANICS (Fg/L)

N-HEXADECANE ND(500) ND(100) ND(10) ND(10) ND(10) 110 ND(10) ND (10)

P066 BIS(2-ETHYLHEXYL) PHTHALATE 7,200 350 >200 ND(10) ND(10) ND(100) ND(10) ND (10)

P068 DI-N-BUTYL PHTHALATE 100 ND(100) ND(10) ND(10) ND(10) ND(100) ND(10) ND (10)

N-DODECANE 3,000 ND(100) ND(10) ND(10) ND(10) ND(1,000) ND(10) ND (10)

5-METHYL-1H-BENZOTRIAZOLE 2,000 2,200,000 >2,000 2,200 17,000 90,000 120 200

P065 PHENOL ND(500) ND(100) 110 64 93 280 ND(10) ND (10)

N-TETRADECANE ND(500) ND(100) ND(10) ND(10) ND(10) 140 ND(10) ND (10)

GLYCOLS (mg/L)

ETHYLENE GLYCOL NA NA ND(10) ND(10) 3,200 3,000 ND(10) ND (10)

DIETHYLENE GLYCOL NA NA ND(5.0) ND(5.0) >20,000 15,000 ND(5.0) ND (5.0)

PROPYLENE GLYCOL NA NA 2,700 1,200 16,000 160,000 ND(5.0) 180
Table 8-4 (Continued)

Section 8.0 - Wastewater Characterization

Priority Ethylene Propylene Composite of Kansas City Bradley Greater Bradley

Pollutant Glycol- Glycol- Small Large Lagoon International International Rockford International

Code Analyte Based Fluid Based Fluid Lagoon and Tank Airport Airport Airport Airport

Type I Deicing Fluids

(50% Solution) Albany International Airport

Raw Wastewater Samples Samples

Storm Water

Outfall

ND - Analyte not detected (followed by detection limit).

NQ - Analyte not quantified due to matrix interference.

8-27

METALS (Fg/L)

ALUMINUM 230 120 530 1,100 860 1,100 270 69

P114 ANTIMONY ND(20) 91 ND(2.0) ND(2.0) ND(2.0) ND(20) ND(2.0) 2.3

P115 ARSENIC 24 360 ND(1.0) ND(1.0) 2.8 ND(1.0) 3.4 ND (1.0)

BARIUM 3.0 24 89 86 60 36 31 91

BORON 1,400 36 ND(26) ND(26) ND(26) ND(26) ND(26) 220

P118 CADMIUM 240 6.7 1.0 1.4 3.4 11 ND(1.0) ND (1.0)

CALCIUM 1,100 2,000 38,000 36,000 34,000 33,000 14,000 41,000

P119 CHROMIUM 3.5 ND(1) 2.7 3.6 5.0 7.2 3.7 ND (1.0)

P120 COPPER 20 44 ND(9.0) 14 14 44 9.2 ND (9.0)

IRON 230 670 3,500 9,200 1,200 3,400 810 7,100

P122 LEAD 53 110 6.6 9.5 15 50 4.3 ND (2.0)

MAGNESIUM ND(89) ND(70) 7,100 7,400 2,500 2,000 3,000 12,000

MANGANESE ND(1.0) 40 1,100 1,000 170 140 360 1,600

P123 MERCURY NQ NQ ND(0.2) ND(0.2) ND(0.2) 0.29 ND(0.2) ND (0.2)

POTASSIUM 20,000 NA 64,000 57,000 13,000 ND(900) 64,000 ND (900)

P125 SELENIUM NQ 890 ND(2.0) ND(2.0) ND(20) ND(20) ND(2.0) ND (20)

P126 SILVER ND(5.0) ND(4.0) ND(5.0) ND(5.0) ND(5.0) 6.6 ND(5.0) ND (5.0)

SODIUM 36,000 24,000 62,000 63,000 11,000 10,000 7,900 75,000

P127 THALLIUM ND(1.0) 330 ND(1.0) ND(1.0) ND(1.0) ND(10) ND(1.0) ND (1.0)

TIN 1,100 1,300 12 12 20 180 ND(5.0) ND (4.0)

TITANIUM ND(3.0) ND(4.0) 6.4 11 68 44 9.1 ND (5.0)

VANADIUM ND(11) ND(10) ND(10) ND(10) ND(10) 16 ND(10) ND (10)
Table 8-4 (Continued)

Section 8.0 - Wastewater Characterization

Priority Ethylene Propylene Composite of Kansas City Bradley Greater Bradley

Pollutant Glycol- Glycol- Small Large Lagoon International International Rockford International

Code Analyte Based Fluid Based Fluid Lagoon and Tank Airport Airport Airport Airport

Type I Deicing Fluids

(50% Solution) Albany International Airport

Raw Wastewater Samples Samples

Storm Water

Outfall

8-28

P128 ZINC 190 440 110 130 140 340 45 ND (10)

CLASSICAL WET CHEMISTRY (mg/L)

AMMONIA AS NITROGEN 3.0 5.4 88 84 3.9 23 46 1.1

BIOCHEMICAL OXYGEN DEMAND (5-DAY) NA NA 12,000 9,800 5,100 39,000 >7.3 61

TOTAL ORGANIC CARBON (TOC) 410,000 210,000 2,400 2,500 3,000 35,000 12 26

SILICA-GEL TREATED HEXANE EXTRACTABLE

MATERIAL NA NA ND(5.0) ND(5.0) 6.0 65 ND(6.0) ND (5.0)

HEXANE EXTRACTABLE MATERIAL NA NA ND(6.0) ND(6.0) 10 170 100 ND (5.0)

WHOLE EFFLUENT TOXICITY (LC 50, endpoint

(%))

CERIODAPHNIA DUBIA (48-HOUR ACUTE) NA NA NA NA 58 1.2 NA >100 1 1 1

PIMEPHALES PROMELAS (96-HOUR ACUTE) NA NA NA NA 40 3.1 NA >100 1 1 1

ND - Analyte not detected (followed by the detection limit).

NA - Analyte not analyzed.

> - Minimum concentration.

1 - Wastewater expected to be toxic to aquatic life due to high ammonia concentration.

LC 50, endpoint (%) - Percentage of raw wastewater that kills 50% of the aquatic test population (i.e., the lower the percentage, the greater the aquatic toxicity). When less

than 50% of the test populations dies in all sample concentrations tested up to and including the 100% raw wastewater, the results are reported as >100%.
Section 8.0 - Wastewater Characterization

8-29

Table 8-5

Analytical and Toxicity Data Provided by Fluid Formulators

for Type I Aircraft Deicing Fluids

Parameter Concentrate Octaflo Concentrate

UCAR Aircraft Deicing Fluid TM 

Ethylene glycol (% weight) 92 N/A

Propylene glycol (% weight) N/A 88

Chemical oxygen demand (mg O2/mg of fluid) 1.14 NA

Percentage biodegradation 69 (5-day) 61 (7-days)

85 (10-days) 84 (14-days)

96 (20-days) 93 (21-days)

Rainbow trout (LC50, 96-hour)(mg/L) 17,100 NA

Fathead minnows (LC50, 96-hour)(mg/L) 22,000 1,250

Daphnia magna (LC , 48-hour)(mg/L) 50 NA 750

N/A - Not applicable.

NA - Data not available.
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents

9-1

9.0 TOXICITY OF DEICING/ANTI-ICING AGENTS

During aircraft and airfield deicing operations, deicing agents are released to the

land, air, and surface waters. Release of these agents may adversely affect the environment,

aquatic wildlife, and human health. Aircraft deicing/anti-icing fluids (ADFs) typically contain

water, glycols, and additives. The toxicity exhibited by ADFs is due in part to the presence of

glycols (which typically make up approximately 45% to 65% of the total fluid by weight when

applied), but is also due to the additives contained in the fluids. Although additives comprise a

small percentage of ADFs (e.g., less than 2%), they may be responsible for a disproportionate

share of the toxicity of ADFs. The toxicity of pavement deicing agents is mainly due to the

application of glycols and urea; however, there are other more benign pavement deicing agents

currently used. 

Several toxicity studies have been performed using pure ethylene glycol and

propylene glycol but few studies have been performed using formulated ADFs. The formulations

are considered trade secrets, and only limited information is currently available on the actual

chemical compositions of formulated ADFs. Some information is available on the types of

compounds that may be included as additives in ADFs. The fluid manufacturers indicate that their

formulas change often, potentially as often as every year. In general, toxicity studies are available

for pavement deicers either from literature sources or from the manufacturers. 

Sections 9.1 and 9.2 discuss toxicity tests performed to determine the aquatic and

mammalian (including human) health effects of pure ethylene glycol and propylene glycol and of

formulated ADFs containing ethylene or propylene glycol, respectively. Section 9.3 discusses

tests performed using pure diethylene glycol and formulated deicing/anti-icing fluid containing

diethylene glycol, a freezing-point depressant that is commonly used in deicing/anti-icing fluids in

Europe. Diethylene glycol is also a byproduct in the manufacturing of ethylene glycol. This

section also discusses the toxicity of isopropanol, another possible freezing point depressant

alternative. Section 9.4 discusses the toxicity of runway deicing chemicals which include urea,
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents

9-2

potassium acetate, sodium formate, calcium magnesium acetate, and others. All tables are

presented at the end of this section.

9.1 Comparison of Pure Ethylene Glycol to Pure Propylene Glycol

Ethylene glycol and propylene glycol are synthetic clear liquid substances that

absorb water. Ethylene glycol is classified as a hazardous air pollutant (HAP) by Congress, and is

required to be reported by users under the Comprehensive Environmental Response,

Compensation and Liability Act (CERCLA) if 5,000 pounds or more in a 24-hour period are

released to the environment (see Section 13.2.1 for more information on CERCLA reporting). 

Propylene glycol is similar in chemical and physical properties to ethylene glycol, but is not

classified as a HAP and is not required to be reported if released. In addition to its use as a

deicing/anti-icing agent, propylene glycol is commonly used in small amounts as a food additive

and in cosmetics and certain medicines to absorb moisture. 

Several toxicity studies have been performed using pure ethylene glycol and

propylene glycol. The results of these studies generally show that both ethylene glycol and

propylene glycol are similar in aquatic toxicity and are fairly nontoxic to the aquatic environment. 

Ethylene glycol has been proven to be toxic to mammals, especially humans, when

directly ingested (1). It is also classified as a teratogen (likely to cause birth defects) if ingested in

large doses (1). When propylene glycol is ingested in regulated amounts as a food additive, it

does not have the same toxic effects as ethylene glycol (2). Neither ethylene glycol nor propylene

glycol is believed to be toxic by adsorption through the skin or by breathing air containing mists

or vapors of either compound.

9.1.1 Aquatic Toxicity

Both ethylene glycol and propylene glycol exhibit similar aquatic toxicity

characteristics. Acute and chronic tests have been performed for both glycols. Data were
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents

9-3

acquired from several sources, particularly individual studies that performed similar tests on both

ethylene glycol and propylene glycol. Tests were performed on both freshwater and marine

aquatic life. Acute tests were performed to determine the lethal concentration for 50% of the

sample population (LC50) over a short period of time (48 to 96 hours). Chronic tests were

performed over a longer period of time (7 to 14 days). 

Table 9-1 summarizes aquatic toxicity data from studies that directly compare

ethylene glycol and propylene glycol under the same or similar experimental conditions. In

general, the data show that ethylene glycol and propylene glycol exhibit aquatic toxicological

effects at concentrations within the same order of magnitude. Although EPA does not use such a

system, the U.S. Fish and Wildlife Service Classification System for Acute Exposures defines

“relatively harmless” as any chemical with an LC50 above 1,000 mg/L (3). The test results shown

in Table 9-1 indicate that ethylene glycol and propylene glycol may be classified as “relatively

harmless,” as defined by the U.S. Fish and Wildlife Service.

The results show that both ethylene glycol and propylene glycol exhibit acute

toxicity (LC50) at a concentration above 10,000 milligrams per liter (mg/L). Toxicity values vary

based on the species tested. The lowest LC for ethylene glycol and propylene glycol occurred at 50

a concentration of 27,600 mg/L and 23,800 mg/L, respectively, among sheepshead minnow

during a 96-hour test (4). 

Table 9-2 lists additional aquatic toxicity studies performed using either ethylene

glycol or propylene glycol. The data from these studies may not be directly comparable to other

available data due to differences in experimental conditions (e.g., dissolved oxygen concentration,

life stage, temperature). The results of these additional studies generally agree with the data

presented in Table 9-1. Table 9-2 presents the additional data sources and their references.
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents

9-4

9.1.2 Mammalian Toxicity

There are three main exposure routes for ethylene glycol and propylene glycol:

inhalation, oral, and dermal (through skin adsorption). Inhalation and dermal exposure to

ethylene glycol are not expected to exhibit toxic effects (2). Data based on human oral exposure

(accidental or intentional) of ethylene glycol are available, and several animal studies have been

used to corroborate the findings (2). When ingested, ethylene glycol quickly breaks down in the

body. As it breaks down, it forms chemicals that crystallize and affect kidney functions, and

forms acidic chemicals that alter the body’s normal chemical balance (2). Inhalation, oral, and

dermal exposure to propylene glycol are not expected to lead to toxic effects, although some data

suggest oral exposure to propylene glycol may cause allergic reactions with minor side effects (2). 

Although propylene glycol is approved for use in small amounts as a food additive for human

consumption, the Food and Drug Administration (FDA) recently excluded propylene glycol from

its generally recognized as safe (GRAS) status in or on cat food (61 FR 19542). The FDA

concluded that there are significant questions about the safety of propylene glycol in cat food

based on scientific literature (5). Propylene glycol also quickly breaks down in the body but does

not form crystals or acidic chemicals in the body (2).

For both ethylene glycol and propylene glycol, information on several different

health effects over varying periods of time (acute and chronic) were collected. These health

effects include: lethal effects, systemic effects, immunological and lymphoreticular effects,

neurological effects, reproductive effects, developmental effects, genotoxic effects, and

carcinogenic effects. Levels of effects are divided into two categories: no-observed-adverse-effect

levels (NOAELs) and lowest-observed-adverse-effect-levels (LOAELs). LOAELs are classified

into “less serious” (i.e., effects not expected to cause significant dysfunction or death) or

“serious” (i.e., effects that evoke failure in a biological system and can lead to morbidity or

mortality). Below is a summary of the results of several studies (e.g., inhalation, oral, and dermal)

compiled by the U.S. Department of Health and Human Services on these different health effects

of ethylene glycol and propylene glycol (2). 
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents

9-5

9.1.2.1 Inhalation Exposure

There are limited data available for ethylene glycol and propylene glycol that

describe the human health effects associated with breathing air containing either glycol.

C Lethal - No evidence is currently available in which humans or animals died

after inhalation exposure to either glycol. Clinical studies indicate that

inhalation of ethylene glycol and propylene glycol is not likely to result in

death.

C Systemic - Systemic effects on humans included irritation and reports of

headache following inhalation exposure to ethylene glycol; no data are

currently available for systemic effects on humans following propylene

glycol exposure. Animals exposed to propylene glycol did not experience

serious systemic effects. 

C Immunological and lymphoreticular - No evidence is currently available

that links immunological effects to inhalation of either ethylene glycol or

propylene glycol.

C Neurological - No evidence is currently available that links neurological

effects to inhalation of either ethylene glycol or propylene glycol.

C Reproductive - No evidence is currently available that links reproductive

effects in humans to inhalation of ethylene glycol and propylene glycol;

however, in one study, mice exposed to ethylene glycol exhibited increased

postimplantation loss (i.e., exhibited increased occurrence of miscarriage). 

No evidence is currently available that links reproductive effects in animals

to inhalation of propylene glycol.

C Developmental - No evidence is currently available that links

developmental effects in humans to inhalation of ethylene glycol and

propylene glycol; however, mice exposed to ethylene glycol exhibited

skeletal malformations and reduced fetal body weight. No evidence is

currently available that links developmental effects in animals to inhalation

of propylene glycol.

C Genotoxic - No evidence is currently available that links in vivo genotoxic

effects in humans or animals to inhalation of either ethylene glycol or

propylene glycol.
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents

9-6

C Carcinogenic - One study that examined health histories of workers in a

chemical plant that were exposed to ethylene glycol concluded that

inhalation of ethylene glycol poses negligible cancer risks. No evidence is

currently available that links inhalation of propylene glycol to cancer.

9.1.2.2 Oral Exposure

Significant data exist that show the adverse effects associated with oral exposure

to ethylene glycol. The main exposure route is direct ingestion. The results show that, when

ingested, ethylene glycol can be considered acutely toxic because, even after one ingestion, it can

significantly adversely impact human health and may even lead to death. Propylene glycol is a

common additive in foods, and is not associated with serious adverse effects following ingestion

at low levels.

C Lethal - In cases where humans directly ingested ethylene glycol and died,

the lethal amount ranged from 2,379 to 23,786 mg/kg, although some

cases exist where the amount ingested is not known. One study concluded

that a dose of 1,559 mg/kg of ethylene glycol is lethal (1). Rats and dogs

fed similar doses to each other resulted in at least 10% and, in some cases,

100% mortality. No cases were found in which humans died after

ingesting propylene glycol. One case did report a horse dying of

respiratory failure after ingesting propylene glycol. Studies of oral

exposure of propylene glycol to rats resulted in no deaths.

C Systemic - Serious systemic effects in humans and animals occurred

following ingestion of ethylene glycol, including cardiovascular,

gastrointestinal, renal, and metabolic effects. Less serious effects in

animals, including gastrointestinal, hematological, and endocrine effects,

resulted after ingestion of propylene glycol.

C Immunological and lymphoreticular - No evidence is currently available

that links immunological effects to ingestion of either ethylene glycol or

propylene glycol. 

C Neurological - Neurological effects were reported in humans, and are

among the first symptoms in humans following ethylene glycol ingestion.

Such effects include ataxia, slurred speech, irritation, restlessness, and

disorientation and may be followed by convulsions and coma. Ingestion of
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents

9-7

propylene glycol may also result in neurological effects in allergic

individuals, including stupor and repetitive convulsions.

C Reproductive - No evidence is currently available that links reproductive

effects in humans to ingestion of either ethylene glycol or propylene glycol. 

Reproductive studies on mice and rats following ingestion of ethylene

glycol are inconclusive, and no adverse reproductive effects were found in

mice after ingesting propylene glycol.

C Developmental - No evidence is currently available that links

developmental effects in humans to ingestion of either ethylene glycol or

propylene glycol. Ingestion of ethylene glycol caused harmful

developmental effects in mice, including reduced litter sizes, reduced fetal

body weight, and malformations. No evidence is currently available that

links development effects in mice to ingestion of propylene glycol.

C Genotoxic - No evidence is currently available that links in vivo genotoxic

effects in humans to ingestion of ethylene glycol or propylene glycol. Rats

receiving oral doses of ethylene glycol exhibited no lethal mutations. 

C Carcinogenic - No evidence is currently available that links cancer in

humans to ingestion of ethylene glycol. In two different studies performed

on mice and rats, ingesting ethylene glycol over a two-year period did not

produce carcinogenic results. No information is currently available that

links ingestion of propylene glycol to cancer.

9.1.2.3 Dermal Exposure

Dermal exposure of ethylene glycol and propylene glycol is not likely to cause

adverse human or animal impacts. 

C Death - No evidence is currently available that links death to dermal

exposure of either ethylene glycol or propylene glycol.

C Systemic - No serious systemic effects in humans or animals were found

following dermal exposure to ethylene glycol or propylene glycol, with one

exception. Serious systemic effects were found in an infant with serious

burns who was treated with a dermal dressing that included high levels of

propylene glycol. The infant suffered acute respiratory acidosis and

cardiorespiratory arrest. After being resuscitated, the baby was discovered

to have serious neurological damage. Although the actual source of the
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents

9-8

infant’s problem could not be determined, propylene glycol cannot be ruled

out as the potential harmful agent.

C Immunological and lymphoreticular - No evidence is currently available

that links immunological effects in humans or animals to dermal exposure

to ethylene glycol or propylene glycol. However, since propylene glycol is

widely used in the pharmaceutical industry for dermally applied

medications, several studies were performed to investigate its potential to

irritate the skin. The results of the studies show that propylene glycol has

“marginal irritant properties.”

C Neurological - No evidence is currently available that links neurological

effects in humans or animals to dermal exposure to ethylene glycol or

propylene glycol.

C Reproductive - No evidence is currently available that links reproductive

effects in humans to dermal exposure to ethylene glycol. Pregnant mice

dermally exposed to ethylene glycol exhibited no adverse reproductive

effects. No evidence is currently available that links reproductive effects in

humans or animals to dermal exposure to propylene glycol.

C Developmental - No evidence is currently available that links

developmental effects in humans to dermal exposure to ethylene glycol. 

Pregnant mice exposed to ethylene glycol exhibited no adverse

developmental effects. No evidence is currently available that links

developmental effects in humans or animals to dermal exposure to

propylene glycol.

C Genotoxic - No evidence is currently available that links genotoxic effects

in humans or animals to dermal exposure to ethylene glycol or propylene

glycol.

C Carcinogenic - No evidence is currently available that links carcinogenic

effects in humans or animals to dermal exposure to ethylene glycol. No

evidence is currently available that links carcinogenic effects in humans to

dermal exposure to propylene glycol. No increase in tumors was found in

one study on mice after twice weekly applications of propylene glycol to

skin.

Table 9-3 presents toxicity data for humans following dermal, oral, and inhalation

exposure to ethylene glycol and propylene glycol. Unlike aquatic toxicity tests, tests performed

on humans and animals using ethylene glycol and propylene glycol almost always focused on
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents

9-9

either ethylene or propylene glycol, but not both, and hence were performed under various

conditions. Therefore, the toxicity results are not directly comparable. Accordingly, the data in

Table 9-3 show ethylene glycol results followed by propylene glycol results, and not side by side. 

In addition, no human toxicity data are currently available for inhalation and oral exposure to

propylene glycol and dermal exposure to ethylene glycol. It is important to recognize that more

studies have been performed using ethylene glycol than for propylene glycol.

9.2 Toxicity of Additives and Formulated Aircraft Deicing/Anti-Icing Fluids

(ADF)

ADFs typically consist of a formulation of ethylene glycol or propylene glycol,

water, and chemical additives such as flame retardants and corrosion inhibitors. The additives

contribute significantly to the overall toxicity of ADFs. For example, available data demonstrate

that the additives in ADFs may cause adverse aquatic toxic effects (6). For these reasons, it is

important to examine the toxicity of formulated fluids in addition to that of pure ethylene glycol

and propylene glycol to determine the toxicological effects of ADFs released to the environment

from airport deicing/anti-icing operations. The identity of the actual chemicals used as additives is

not known because the ADF manufacturers claim this information confidential; however, general

information is known about the types of additives and their possible role in the toxicity of ADFs. 

Section 9.2.1 discusses this general information. Sections 9.2.2 and 9.2.3 provide available

toxicity data for ADFs and compare toxicity among various types of ADFs. 

Based on available data, the toxicity exhibited by pure ethylene glycol and

propylene glycol is significantly lower, and therefore less toxic, than the corresponding formulated

fluids. The reason for this difference is the toxicity of the chemicals that are added, albeit in small

amounts, to formulated fluids. Test results indicate that formulated fluids are more toxic than

pure glycol substances (1). For example, in a study conducted at Stapleton Airport in Denver,

Colorado, a propylene glycol-based ADF exhibited significantly more acute aquatic toxicity than

pure propylene glycol. In chronic studies performed at the airport, the concentration that inhibits

growth and reproduction in 25% of the test organisms (IC25) of pure propylene glycol for fathead
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents

9-10

minnows was 6,941 mg/L, whereas the IC25 of propylene glycol-based deicing ADF (type

unknown) was 112 mg/L (1). The lower the toxic concentration value, the more toxic the

substance. Note, however, that both of these studies were performed several years ago, and more

recent ADF formulations would likely exhibit less toxicity. 

9.2.1 Aircraft Deicing Fluid Components

As stated previously, the identity of many of the chemical compounds that are

added to deicing fluids is unknown; however, general information about the types of additives that

may be included in fluid packages is known. For example, the Air Transport Association (ATA)

prepared a list of deicing fluid constituents in 1994 (7). According to this list, typical ADF

components include or have included: 

C Ethylene glycol or propylene glycol;

C Water;

C Surfactants (wetting agents);

C Corrosion inhibitors (including flame retardants);

C pH buffers;

C Dyes;

C 1,4-Dioxane; and

C Complex polymers (thickening agents in Type II and Type IV ADFs).

Other common additives (or manufacturing byproducts) include diethylene glycol, ethylene oxide,

and acetaldehyde (1). 

Deicing fluids are composed mostly of glycol and water. The remaining

components comprise approximately 1% or less of Type I fluids and 2% or less of Type II and

Type IV fluids (8). ADFs are required to meet performance-based standards that are established

by the Society for Automotive Engineers (SAE). SAE standards for deicing fluids can be found

in Aerospace Material Specification (AMS) 1424, and for anti-icing fluids in AMS 1428. ADFs

would be unable to meet SAE standards without additives. Manufacturers and formulators have

attempted to reduce the toxicity of additives present in their aircraft deicing/anti-icing fluid

formulations and, when possible, to use environmentally benign chemicals. For example, one
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents

9-11

manufacturer uses a food-grade dye in its deicing fluids that is photoreactive and readily degrades

in the environment. Manufacturers and formulators also stress that some additives perform

multiple functions. They claim that they could replace these additives with several less toxic

additives, but the combined toxicity may be greater than the toxicity of the original additive (9). 

As discussed in Section 13.5.3, the SAE fluids subcommittee is currently working to set an ADF

toxicity standard in the near future.

The potential adverse environmental and health effects of each of the ADF

components are discussed below. 

9.2.1.1 Glycol

Fluid formulations contain varying amounts of glycol. Typical Type I ADFs

contain approximately 90% glycol (by weight) in concentrated form. As applied, they contain

between 30% and 60% glycol (typically approximately 50%), whereas Type II and Type IV ADFs

contain higher percentages of glycol, closer to 65 percent. In general, by themselves, both

ethylene glycol and propylene glycol are relatively nontoxic to the aquatic environment. Ethylene

glycol is fairly nontoxic to mammals, except when ingested. Several documented cases show that

ethylene glycol, when ingested, may be lethal. Available data indicate that propylene glycol is

nontoxic to mammals. See Section 9.1 for a more detailed discussion on the toxicity of pure

ethylene glycol and pure propylene glycol.

9.2.1.2 Surfactants

Surfactants, or wetting agents, are substances that reduce the surface tension of

fluids and aid fluids in spreading or adhering to aircraft surfaces. They may comprise

approximately 0.4% to 0.5% by volume of deicing fluids (7). Surfactants can be very toxic to

aquatic organisms (1). At acutely toxic concentrations (concentration unknown), the primary

effect on fish would be damage to gill tissue, although it is not known if these tests were

conducted using the same surfactants that are used in deicing fluids (1).
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents

9-12

9.2.1.3 Corrosion Inhibitors and Flame Retardants

Corrosion inhibitors act to prevent aircraft components that have been covered

with deicing/anti-icing fluids from corroding, and flame retardants act to reduce the flammability

hazard created when fluids are applied to metal aircraft surfaces that carry electric currents (6). 

Corrosion inhibitors may comprise up to 0.5% by volume of ADFs and are present at

approximately 100 to 300 mg/L (6, 10). The corrosion inhibitor and flame retardant most

commonly used in deicing fluids is 5-methyl-1H-benzotriazole (common name: tolyltriazole or

TTZ), although 1H-benzotriazole (common name: benzotriazole or BTZ) may also be used. 

Aquatic toxicity data available for TTZ (summarized below) indicate that it is significantly more

toxic than glycols. 

Species Duration (mg/L) Glycol (mg/L) Glycol (mg/L)

LC50 for TTZ LC50 for Ethylene LC50 for Propylene

Bluegill sunfish 96-h LC 31 27,540 Not available

(Lepomis macrochirus)

50

Water flea (Daphnia

magna)

48-h LC50 74 46,300 - 54,700 43,500

Sources: References (6, 11, 12, 13).

Little mammalian toxicity data are available for TTZ, although it is considered

harmful if swallowed and may cause irritation on contact (14). According to the Merck Index, it

has a lethal dose at which 50% of the test organisms die (LD50) of 720 mg/kg for rats (14). BTZ

was identified by Environment Canada’s National Water Research Institute as a potentially toxic

additive in ADFs (10).

Scientists and researchers are currently studying the toxic effects of tolyltriazoles. 

In a study performed by D. Cancilla et al. in 1996, results verified the presence of TTZ and BTZ

in deicing and anti-icing fluids (15). The results also showed that both TTZ and BTZ have

significant Microtox® activity, although TTZ was more acutely toxic than BTZ. Microtox®

testing was conducted using the standard method for various exposure times and temperatures. 
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents

9-13

The median effective toxicity concentration (EC50 ) was measured as the concentration at which

light lost in the sample equals the light remaining in a sample of bioluminescent bacteria. Results

for TTZ and BTZ are presented below.

Compound 5-min. EC (mg/L) 15-min. EC (mg/L) 50 50

Benzotriazole 41 42

Tolyltriazole 6 6

Source: Reference (15).

Another common corrosion inhibitor includes phosphate esters, which may

comprise up to 0.125% by volume of deicing fluids (7). Phosphate esters ((RO)3PO) are

derivatives formed by phosphoric acids and alkyl or aryl alcohols. The degree of toxicity of

phosphate esters varies. Some phosphate esters can be highly toxic and even carcinogenic (17). 

Other common corrosion inhibitors include sodium nitrite, sodium benzoate, and

borax (17). Corrosion inhibitors are highly reactive with each other and with glycols, which can

result in high biological toxicity (1). In general, corrosion inhibitors are considered toxic

chemicals because of their high reactivity potential (1).

9.2.1.4 pH Buffers

pH buffers are solutions that maintain the fluid at a constant pH. The addition of

alkali or acid would result in only minimal changes to fluid pH. pH buffers are thought to

comprise less than 0.25% by volume of deicing fluids (7). A common pH buffer is potassium

hydroxide (7), which on its own is highly caustic upon contact, may be lethal upon ingestion, and

is extremely corrosive (14). It has an oral LD of 1,230 mg/kg for rats (14). 50
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents

9-14

9.2.1.5 Colorants or Dyes

Colorants or dyes (organic based) are chemicals used to color deicing fluids. They

are thought to comprise less than 0.25% by volume of deicing fluids (7). Deicing fluids are

colored to make them visible so that deicing personnel can see where fluids have been applied and

where they have fallen to the ground. In general, Type I fluids are dyed orange and Type II and

IV fluids are dyed green. Due to the wide range of potential colorants used in ADFs, no useful

information could be collected on the toxicity of colorants or dyes.

9.2.1.6 1,4-Dioxane

1,4-Dioxane is used as a wetting and dispersing agent and is thought to comprise

less than 0.5 mg/L of deicing fluids (7). Dioxane is a suspected carcinogen and/or teratogen (1). 

EPA has reason to believe that some fluid manufacturers have removed 1,4-dioxane from their

formulations. However, it is present in at least one ADF, although, according to the fluid’s

manufacturer, its source is as an impurity that occurs at extremely low levels (18). 1,4-dioxane

has low acute aquatic and mammalian toxicity and may be irritating to humans on contact;

however, it can exhibit significant chronic toxicity (14). Prolonged exposure to 1,4-dioxane has

resulted in several human deaths (14). The oral LD50 in mice and rats is 5,700 mg/kg and 5,200

mg/kg, respectively (14). 

9.2.2 Aquatic Toxicity Data for ADF

Few aquatic toxicity experiments have been performed using formulated ADFs. 

Those that have been performed used a variety of experimental conditions, making it difficult to

directly compare data. Table 9-4 summarizes toxicity data from studies that directly compare

ethylene glycol-based and propylene glycol-based ADFs by fluid type under the same

experimental conditions. Table 9-4 also summarizes all available data for the fathead minnow and

Ceriodaphnia dubia because EPA selected these species for its aquatic toxicity tests (see Section

8.1). It is important to note that the formulation of these fluids frequently changes. Deicing fluid
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents

9-15

manufacturers state that any toxicity data collected using a specific ADF are quickly outdated as

they develop less toxic additives. Information provided by an ethylene glycol-based ADF

manufacturer shows toxicity in current formulations to be as much as an order of magnitude less

than older formulations (8). Aquatic toxicity data from two deicing fluid formulators for

concentrated deicing fluid (i.e., Type I) are summarized below. Both of these formulations are

currently used in the U.S.

Species Endpoint Concentration (mg/L) Fluid Concentration (mg/L)

Duration and Type I EG-Based Deicing Fluid Type I PG-Based Deicing

Fathead Minnow 96-h LC 22,000 1,250

(Pimephales promelas)

50

Rainbow Trout 96-h LC 17,100 NA

(Oncorhynchus mykiss)

50

Water Flea (Daphnia

magna)

48-h EC50 44,000 NA

Water Flea (Daphnia

magna)

48-h LC50 NA 750

Reference: (19, 20).

NA - Not available.

LC - Median lethal concentration that kills 50% of the test organisms. 50

EC50 - The median effective concentration. The concentration of a substance that causes a specified effect (generally

sublethal rather than acutely lethal) in 50% of the test organisms.

The results above and in Table 9-4 show that, for most aquatic species, the current

ethylene glycol-based Type I ADFs exhibit acute aquatic toxicological effects at higher

concentrations (i.e., are less acutely toxic) than the current propylene glycol-based Type I ADFs. 

Note that these data were collected under laboratory conditions in compliance with SAE

specifications and not under actual field conditions. 

Few sources of toxicity data that directly compare Type IV ethylene glycol-based

and propylene glycol-based ADFs are available. Toxicity data for Type IV ADF provided by two

fluid manufacturers are presented below. Both of these formulations are currently used in the

U.S. Note that these data show toxicity results similar to those for Type II ADFs and that data
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents

Although EPA does not use such a system, the U.S. Fish and Wildlife Classification System for Acute Exposures 1

defines “relatively harmless” as any chemical with an LC above 1,000 mg/L (3). 50

9-16

were collected under laboratory conditions in compliance with SAE specifications and not under

actual field conditions. 

Species Endpoint Concentration (mg/L) Concentration (mg/L)

Duration and Deicing/Anti-icing Fluid Deicing/Anti-icing Fluid

Type IV EG-Based Type IV PG-Based

Fathead Minnow 96-h LC 370 NA

(Pimephales promelas)

50

Rainbow Trout 96-h LC 380 NA

(Oncorhynchus mykiss)

50

Water Flea (Daphnia

magna)

48-h LC50 630 975

Reference: (19, 20).

NA - Not available.

LC - Median lethal concentration that kills 50% of the test organisms. 50

In general, Type I ADFs, regardless of chemical basis, may be considered

“relatively harmless” per the U.S. Fish and Wildlife Service Classification System . In contrast, 1

Type II/IV ADFs, with an LC50 in the range of 10 to greater than 1,000 mg/L are considered in

the range of “slightly toxic” to “relatively harmless” (3). 

Based on the available data, the current propylene glycol-based Type IV fluid

exhibits toxicity at similar concentrations to the same manufacturer’s current Type I fluid. These

results suggest that additives in propylene glycol-based Type IV fluid may not significantly impact

aquatic toxicity. However, the ethylene glycol-based Type IV fluid is significantly more toxic to

aquatic life than the same manufacturer’s Type I fluid. 

Table 9-5 lists additional toxicity studies performed using either only ethylene

glycol-based or propylene glycol-based ADFs on only Type I or Type II fluids. The data from

these studies may not be directly comparable due to differences in experimental conditions (e.g.,
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents

9-17

temperature, pH). The results of these studies generally agree with the data provided in Table

9-4. 

As discussed in Section 8.1, General Mitchell International Airport (GMIA)

performed aquatic toxicity tests under actual field conditions (i.e., in-stream sample collection

during a storm event). The results show an acute toxic ADF in-stream concentration to fathead

minnows and Ceriodaphnia dubia above 1,000 mg/L (i.e., LC > 1,000 mg/L). 50

Aquatic toxicity tests performed by Cornell, Pillard, and Hernandez show different

test organisms to be affected by different ADF components (6, 21). Tests were performed using

pure propylene glycol, propylene glycol and TTZ, propylene glycol and the additives package

excluding TTZ (e.g., only surfactants, dyes, buffers), and two propylene glycol-based fully

formulated fluids (from different manufacturers). The Ceriodaphnia dubia (C. dubia) and fathead

minnow were only highly affected by the propylene glycol and additives package (i.e., excluding

TTZ) while Microtox® organisms were only highly affected by the propylene glycol and TTZ

(i.e., excluding the additives package). In general, the two formulated fluids (shown below as an

average), which yielded similar results, were the most toxic combination to all test species. 

However, the effects of the fully formulated fluids on each test organism were similar (within an

order of magnitude) to the effects of the most highly affected component alone, indicating that the

most highly affected component controls the toxicological response as shown in the chart below. 

These results also suggest very different toxicity mechanisms for macroorganisms (e.g., C. dubia

and fathead minnow) and microorganisms (e.g., Microtox® organisms) (6, 21). Table 9-6

presents the results of the toxicity tests.
0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

PG only PG + TTZ PG + AdPack Fully Formulated

LC50 (as mg/L of PG)

C. dubia

Fathead minnow

Microtox

PG - Propylene Glycol

Section 9.0 - Toxicity of Deicing/Anti-Icing Agents

9-18

9.2.3 Mammalian Toxicity Data for Aircraft Deicing Fluids

No mammalian toxicity data are currently available for ADFs. However, available

aquatic toxicity data for ADFs as compared to pure ethylene glycol and propylene glycol, as well

as data indicating the potential for ADF additives to cause adverse health effects in mammals,

indicate that ADFs will exhibit mammalian toxicity at lower concentrations than pure glycols. As

discussed in Section 9.2.1, some additives are known or suspected carcinogens or teratogens.

9.3 Toxicity of Other Freezing-Point Depressants

Ethylene glycol and propylene glycol are the most commonly used freezing point

depressants in ADFs, although other freezing point depressants may be used or are currently

being researched for approved use by the industry. Diethylene glycol is an SAE-approved

freezing point suppressant for use in ADFs; however, no ADFs that are primarily diethylene

glycol are currently approved for use in the U.S. Diethylene glycol-based deicing fluids are more

commonly found in Europe, although some formulations used in the United States may contain a

small portion of diethylene glycol (17). 
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents

9-19

Isopropyl alcohol (isopropanol) is currently used by the U.S. Air Force as a

pavement deicer, but is not currently an SAE- or FAA-approved freezing point depressant for

aircraft deicing (17). Although isopropanol is highly flammable and cannot meet the SAE

specifications without the addition of fire suppressants, it may be a viable alternative due to its

low cost and effectiveness as a freezing point depressant. EPA believes that research is currently

being performed on the use of isopropanol for aircraft deicing. 

Sections 9.3.1 and 9.3.2 discuss the toxicity of diethylene glycol and isopropanol,

respectively.

9.3.1 Diethylene Glycol

Diethylene glycol exhibits similar toxicity characteristics to ethylene glycol but it

has a higher eutectic temperature (i.e., minimum freezing point depression temperature) (22). 

EPA believes that diethylene glycol is not considered a favorable alternative at this time because

of these factors. However, trace amounts of diethylene glycol may be commonly found in

ethylene glycol-based ADFs (17). 

Diethylene glycol is a clear, colorless, syrupy liquid that may be used as an antifreeze, but is more commonly used in the petroleum refining industry as a solvent extractor (23). 

In its pure form, it has a freezing point of approximately -10E C (23). The freezing point of a

40% diethylene glycol and 60% water mixture is -18E C, while that of a 50/50 mixture is -28E C

(the freezing point of a 50/50 mixture of ethylene glycol and water is -35E C) (14). 

Fewer sources of aquatic toxicity data are available for diethylene glycol as

compared to ethylene glycol and propylene glycol. Available data are summarized in Table 9-7

and show that diethylene glycol exhibits aquatic toxicity characteristics similar to ethylene glycol

and propylene glycol. Based on these data, diethylene glycol may be considered “relatively

harmless,” as classified by the U.S. Fish and Wildlife Service (3). 
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents

9-20

Diethylene glycol, like ethylene glycol, can be fatal if ingested, but it is not as toxic

to mammals or humans via other exposure routes (e.g., inhalation, dermal). Table 9-8

summarizes mammalian toxicity data for diethylene glycol. 

Diethylene glycol is an eye and human skin irritant (24). Exposure to diethylene

glycol may result in nausea, vomiting, headaches, unconsciousness, convulsions, and even death

(24). It can also cause degenerative changes in the kidneys and liver, respiratory failure,

cardiovascular collapse, acute renal failure, and brain damage, among others (24). 

In one documented case, children were accidentally given oral medication that was

contaminated with diethylene glycol (at a median concentration of 14.4%). The median estimated

toxic dose of diethylene glycol was estimated at 1.34 mL/kg and caused renal failure, hepatitis,

pancreatitis, central nervous system impairment, coma, and death (25). 

In a study performed to document clinical signs of toxicity in time-pregnant mice,

researchers found that 1,250 mg/kg/day of diethylene glycol was a no-observed-adverse effectlevel for maternal and developmental toxicity. Mice fed 5,000 mg/kg/day of diethylene glycol

produced significant maternal toxicity (e.g., increased water intake, increased kidney weights) but

no developmental toxicity. Mice fed 10,000 mg/kg/day of diethylene glycol produced significant

maternal toxicity (e.g., increased water intake, decreased food consumption, increased kidney

weights and renal lesions), significant developmental toxicity (e.g., decrease in fetal body weight),

and resulted in one death during the study. Researchers found that diethylene glycol was not

teratogenic in mice at the doses tested in the study (26).

9.3.2 Isopropyl Alcohol (Isopropanol)

Isopropanol is a commonly used chemical, although it is not commonly used for

aircraft deicing. Based on responses to EPA’s 1993 screener questionnaire, 14 airports were

identified as using isopropanol for aircraft deicing; however, EPA was not able to identify any

airports that currently use isopropanol-based ADFs. Reportedly, the National Aeronautics and
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents

9-21

Space Administration (NASA) is researching the use of an alcohol-based ADF. A main drawback

to an isopropanol-based ADF is that it would be corrosive and highly flammable and would,

therefore, need to contain significant amounts of flame retardants, corrosion inhibitors, and other

potentially toxic additives. On the other hand, from a cost perspective, isopropanol is significantly

less expensive than glycols (27).

Isopropanol is a colorless, flammable liquid, that has a slight odor resembling

ethanol and acetone (28). It is used in many industries, including chemical manufacturing and

pharmaceutical manufacturing for solvent applications (23). It is commonly used as a deicing

agent in liquid fuels. In its pure form, it has a freezing point of approximately -88.5E C (23). 

Exposure to isopropanol can irritate the eyes, nose, mouth, and throat, and overexposure can

even cause death (29). It is regulated under Toxic Substances Control Act (TSCA) and Federal

Insecticide, Fungicide, and Rodenticide Act (FIFRA), and must be reported under TRI only if is

being manufactured by a strong acid process, which is not applicable to this industry. 

Available aquatic toxicity data show that isopropanol exhibits aquatic toxicity at

concentrations similar to but slightly less than glycols. The available data are summarized in

Table 9-9. The data also show that isopropanol may be considered “relatively harmless,” as

classified by the U.S. Fish and Wildlife Service (3). 

Isopropanol is considered toxic if ingested in large enough doses, or through the

subcutaneous route. It is considered moderately toxic by intravenous and intraperitoneal routes,

and mildly toxic by dermal contact. Human systemic effects can be the result of ingestion or

inhalation. Experimentally, it has been shown to be teratogenic and cause negative reproductive

effects. It is also considered an eye and skin irritant. Based on inadequate evidence, it is not

classified as a carcinogen; however, there is an increased incidence of nasal sinus cancer in

workers involved in the manufacture of isopropanol by the strong acid process. Exposure to

isopropanol can lead to skin irritation, dizziness, nausea, lowered blood pressure, abdominal pain,

and can even lead to coma and death (29). Table 9-10 summarizes mammalian toxicity data for

isopropanol.
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents

9-22

9.4 Toxicity of Pavement Deicers

Pavement deicing agents may cause significant adverse environmental impacts,

although many airports are beginning to use less harmful agents. Pavement and runway deicing

and anti-icing agents approved by the FAA include urea, ethylene glycol (including an ethylene

glycol-based fluid known as UCAR, containing approximately 50% ethylene glycol, 25% urea,

and 25% water by weight), potassium acetate, calcium magnesium acetate (CMA), sodium

acetate, and sodium formate. Alternative agents that may be used for runway deicing include

isopropanol and propylene glycol. Salts including magnesium chloride, sodium chloride, and

potassium chloride are not approved for use in aircraft operational areas because they are

corrosive to aircraft. Sand is used on some airfields to increase friction and improve aircraft

braking performance. Pavement and runway deicers must meet specifications set by the SAE or

the United States military (MIL-SPEC). Until recently, most commercial airports used urea

and/or glycols to deice pavement areas. Due to negative environmental impacts from these

agents, several airports currently use more environmentally benign agents, such as potassium

acetate, sodium formate, and CMA. Corrosion inhibitors are often added to runway deicers to

meet the SAE and MIL-SPEC specifications. As discussed in Section 9.2.1.3, corrosion

inhibitors may exhibit high mammalian and aquatic toxicity. Each of the approved agents and

resulting adverse aquatic and health effects is discussed below. Available information on the

biochemical oxygen demand of deicing agents can be found in Section 10.1.2.

9.4.1 Urea

Urea is typically applied to pavement and runway areas in granular form. Urea is a

common nutrient for algae and other water plants as a nitrogen source and is not considered

toxic. However, urea degrades by hydrolysis to carbon dioxide and ammonia, which can be very

toxic to aquatic organisms even at very low concentrations. Once ammonia is formed, it either

remains in solution as ammonia or its ionized form (NH4), biologically converts to other nitrogen +

forms (e.g., NO3 or N2), or volatilizes to the air. The following equations show the degradation

of urea:
NH2CONH2

(urea) % 2H2O '> NH %

4 % NH3

% HCO &

3

(1)

NO &

2 % 0.5O2

'> NO &

3

(3)

NH %

4 % 1.5O2

'> NO &

2 % H2O % 2H

%

(2)

Section 9.0 - Toxicity of Deicing/Anti-Icing Agents

9-23

Urea is considered to be nontoxic to aquatic organisms but it can irritate the nose

and throat, causing a sore throat, sneezing or coughing, and shortness of breath in humans (30).

Chronic exposure and acute exposure in high concentrations may cause eye damage, skin redness

or rash (dermatitis), or emphysema (31). Toxicity data for urea are summarized below.

Species Duration Concentration/Dose

Barilius barna 96-h LC50 >9,100 mg/L

Tilapia mossambica 96-h LC50 22,500 mg/L

Leuciscus idus melanotus 48-h LC50 >10,000 mg/L

Water Flea (Daphnia magna) 24-h EC50 >10,000 mg/L

Mosquito (Aedes aegypti) 4-h LC50 60,000 mg/L

Freshwater snail (Helisoma

trivolvis)

24-h LC 30,060 mg/L (adults) 50

24-h LC 18,255 mg/L (juvenile) 50

24-h LC 14,241 mg/L (egg) 50

Rat LD50 (oral) 14,300 mg/kg

LD50 (subcutaneous) 8,200 mg/kg

Mouse LD50 (intravenous) 4,600 mg/kg

Sources: References (30, 31).

LC - Median lethal concentration that kills 50% of the test organisms. 50

EC - The median effective concentration. The concentration of a substance that causes a specified effect (generally 50

 sublethal rather than acutely lethal) in 50% of the test organisms.

LD - Median lethal dose that kills 50% of the test organisms. 50

> - Minimum concentration.

Ammonia in its un-ionized form is one of the urea byproducts that may have

significant adverse aquatic effects and reported LC values in the range of 1 to 10 mg/L (31). 50

Aquatic toxicity data for ammonia in its un-ionized form are summarized below.
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents

9-24

Species Duration Concentration (mg/L)

Fathead minnow (Pimephales

promelas)

96-h LC 0.73 - 3.4; 50

8.2 (hard water)

Goldfish (Carassius auratus) 24-96-h LC50 2 - 2.5

Rainbow trout (Oncorhynchus

mykiss)

24-h LC50 (fertilized egg) >3.58

24-h LC50 (0-50 days old) >3.58

24-h LC50 (85 days old) 0.068

24-h LC50 (adults) 0.097

Water flea (Daphnia magna) 48-h LC50(static test) 189

Water flea (Daphnia pulex) 48-h LC50 (static test) 187

Source: Reference (23).

LC - Median lethal concentration that kills 50% of the test organisms. 50

> - Minimum concentration.

The formation of ammonia is highly dependent on the pH and temperature of a

given stream. The higher the pH and temperature, the more ammonia is formed (Equation 1). 

Another potentially toxic byproduct of urea degradation is nitrous acid (formed from nitrite in an

acidic solution), which reacts with secondary amines to form nitrosamines, many of which are

known carcinogens (33).

The current ammonia criterion (i.e., allowable concentration) established by EPA

for use by permit writers is based on toxicity of ammonia to fish and varies with the temperature

and pH of the receiving stream. The warmer the stream and the higher its pH, the more likely

ammonia will exist in its un-ionized form (i.e., toxic form), and, therefore, the lower EPA’s

maximum allowable concentration of ammonia should be set. The colder the stream and lower

the pH, the higher EPA’s maximum allowable concentration may be set. One factor affecting the

maximum allowable concentration during cold seasons (i.e., deicing seasons) is that, for the most

sensitive invertebrates, the toxicity of ammonia appears to decrease with decreasing temperature. 

Therefore, it is believed that the maximum allowable concentration of ammonia during cold

seasons may be higher than other times of the year. 
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents

9-25

9.4.2 Ethylene Glycol

The use of ethylene glycol as a runway and pavement deicer is becoming less

popular, due to its reporting requirements and adverse environmental impacts. However, it is an

effective freezing point depressant and may still be used at airports subject to extreme

temperatures. The toxicity of ethylene glycol and its potential impacts are discussed in Section

9.1. 

Urea is often combined with ethylene glycol for use as a liquid runway deicer. The

mixture is irritating to the eyes and skin (31). Ingestion can lead to mental sluggishness, difficulty

in breathing, heart failure, kidney and brain damage, and death (31). Mammalian toxicity data for

an ethylene glycol/urea mixture are presented below.

Species Duration Dose (mg/kg)

Rat LD50 (oral) 4,700

LD50 (intraperitoneal) 5,010

LD50 (subcutaneous) 2,800

LD50 (intravenous) 3,260

LD50 (intramuscular) 3,300

Source: Reference (30).

LD - Median lethal dose that kills 50% of the test organisms. 50

9.4.3 Potassium Acetate

Based on EPA-sponsored site visits, potassium acetate is currently the most

commonly used runway and pavement deicer, although airports have expressed concern that it

may degrade insulation in electric systems (e.g., runway lights). An industry workgroup is

currently investigating this issue. Potassium acetate alone is corrosive, so it is mixed with

corrosion inhibitors, and is also slightly flammable. It is typically applied in its liquid form and

may be combined with urea prior to application. 
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents

9-26

Potassium acetate is a common food additive and is relatively nontoxic to

mammals in small doses, although it may cause eye irritation (31). The oral LD50 of potassium

acetate (without additives) is 3,250 mg/kg for rats (14). Data for potassium acetate-based deicers

are presented below. 

Species Duration Concentration/Dose

Fathead minnow (Pimephales

promelas)

 LC50 (duration unknown) >500 mg/L

7-d LC50 >1,500 mg/L

Rainbow trout (Oncorhynchus

mykiss)

96-h LC50 >2,100 mg/L

Water flea (Daphnia magna) 48-h LC50 >3,000 mg/L

Rat LD50 >5,000 mg/kg

Source: Reference (31).

> - Minimum concentration/dose.

The identity and toxicity of corrosion inhibitors typically added to potassium

acetate runway deicers is not currently known. Most airports are pleased with the performance of

potassium acetate deicer, despite its suspected degradation of electric system insulation and higher

cost than other deicers. 

9.4.4 Calcium Magnesium Acetate (CMA)

CMA is typically applied in a solid granular form. It is an effective anti-icer that is

relatively nontoxic to the environment, though it can be cost-prohibitive. Unlike magnesium

chloride and other salts, CMA is not corrosive and, therefore, does not contain corrosion

inhibitors. Aquatic and mammalian toxicity for CMA are summarized below. In addition, the

results of a 28-day oral toxicity study performed on rats showed no observable effects at daily

doses of 1,000 mg/kg (31).
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents

9-27

Species Duration Concentration/Dose 

Rainbow trout (Oncorhynchus mykiss) 96-h LC50 >1,000 mg/L

Water flea (Daphnia magna) 48-h LC50 >1,000 mg/L

Rat LD50 (oral) >5,000 mg/L

LD50 (dermal) >5,000 mg/kg

4-h LC50 (inhalation) 4.6 mg/L

Source: Reference (31).

LC - Median lethal concentration that kills 50% of the test organisms. 50

LD - Median lethal dose that kills 50% of the test organisms. 50

> - Minimum concentration.

9.4.5 Sodium Acetate

Sodium acetate is typically applied in its solid form and is “relatively harmless,”

according to the U.S. Fish and Wildlife standards (31). Sodium acetate is not considered

hazardous, but may irritate the skin on contact or irritate the respiratory tract following inhalation

of dust. Acute aquatic and mammalian toxicity data are summarized below.

Species Duration Concentration/Dose

Water flea (Daphnia magna) 48-h LC50 2,400 mg/L

Fathead minnow (Pimephales promelas) 24-h LC50 2,750 mg/L

Rat LD50 (oral) 3,530 mg/kg

Mouse LD50 (subcutaneous) 8,000 mg/kg

Mouse LD50 (intravenous) 335 mg/kg

Source: Reference (31).

LC - Median lethal concentration that kills 50% of the test organisms. 50

LD - Median lethal dose that kills 50% of the test organisms. 50
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents

9-28

9.4.6 Sodium Formate

Sodium formate is typically applied in a pellet form and is mixed with corrosion

inhibitors to meet the required specifications. Mammalian toxicity data for pure sodium formate

(based on mice) are as follows (31): 

C LD50 (oral) = 11,200 mg/kg; and

C LD (intraperitoneal) = 807 mg/kg. 50

Toxicity data obtained from a sodium formate deicer manufacturer are summarized below. 

Species Duration Concentration/Dose

Water flea (Daphnia magna) 24-h EC50 4,800 mg/L

48-h EC50 4,400 mg/L

24-h EC0 3,300 mg/L

48-h EC0 3,200 mg/L

Zebra fish 96-h LC50 100 mg/L

Rat LD50 (oral) >2,000 mg/L

4-h LC50 (inhalation) >670 mg/L

Source: Reference (31).

LC - Median lethal concentration that kills 50% of the test organisms. 50

EC - The median effective concentration. The concentration of a substance that causes a specified effect (generally 50

 sublethal rather than acutely lethal) in 50% of the test organisms.

LD - Median lethal dose that kills 50% of the test organisms. 50

> - Minimum concentration.

Significant exposure to sodium formate deicer may adversely affect people

suffering from chronic disease of the respiratory system, skin, and/or eyes. In addition, less

sodium formate needs to be applied as compared to several other pavement deicers (e.g., urea)

(17). 
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents

9-29

9.4.7 Alternative Pavement Deicers

Although they are available for use, isopropanol and propylene glycol are not

typically used as runway or pavement deicers at commercial airports. EPA is aware of only one

airport that mixes propylene glycol with hot sand; the average volume of propylene glycol used is

less than 100 gallons per year at this airport. As discussed in Section 9.3.2, isopropanol is a

highly flammable liquid that is also highly volatile. It requires special handling requirements and

provides minimal anti-icing protection because of its high rate of evaporation. See Section 9.3.2

for a more detailed discussion on the toxicity of isopropanol. However, it is significantly less

expensive than other runway deicers on a per gallon basis (27). Propylene glycol’s high cost may

deter airports from using it as a runway deicer alternative. The toxicological effects of propylene

glycol are discussed in Section 9.1. 

9.4.8 Chlorides

Magnesium chloride, sodium chloride, and potassium chloride are all used landside

(i.e., roadway) but not as runway deicers due to their corrosive effects on aircraft and aircraft

components. Salts are commonly used as nutrients and/or dietary supplement food additives in

small doses. Large doses may cause adverse human health effects (e.g., gastrointestinal irritation

or weakness) (14). 

9.4.9 Sand

Sand is nontoxic to the environment and is effective for increasing friction between

aircraft and pavement, but may interfere with the mechanical working of aircraft (e.g., engine

stalls due to ingestion of sand). Sand is often mixed with other deicing agents (e.g., urea) prior to

application. 
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents

9-30

9.5 References

1. U.S. Environmental Protection Agency. Emerging Technology Report: Preliminary

Status of Airplane Deicing Fluid Recovery Systems. September 1995 (DCN

T04674).

2. U.S. Department of Health and Human Services. Toxicological Profile for

Ethylene Glycol and Propylene Glycol. September 1997 (DCN T11084). 

3. U.S. Fish and Wildlife Service. Research Information Bulletin: Acute-Toxicity

Rating Scales. August 1984 (DCN T10500).

4. Ward, T. et al. Comparative Acute Toxicity of Diethylene Glycol, Ethylene

Glycol, and Propylene Glycol to Freshwater and Marine Fish, Invertebrates, and

Algae. ARCO Chemical Company, 1992.

5. 61 Federal Register 19542-19544 (DCN T10568).

6. Cornell, J. et. al. Chemical Components of Aircraft Deicer Fluid: How They

Affect Propylene Glycol Degradation Rates and Deicing Waste Stream Toxicity.

1998 (DCN T10484). 

7. ATA Workshop on Environmental Implications of Aircraft Deicing. February 1994

(DCN T4668).

8. U.S. Environmental Protection Agency. Meeting Summary Union Carbide

Corporation. May 1998 (DCN T10298).

9. Meeting Summary for Albany Aircraft Deicing Summit. March 1999 (DCN

T10542).

10. Environment Canada. Scientific Considerations in the Development of a Revised

CEPA Glycol Guideline Value. November 1996 (DCN T10376).

11. Abdelghani, A.A., A.C. Andersion, G.A. Khoury, and S.N. Chang. Fate of

Ethylene Glycol in the Environment. 1990.

12. Ward, T. et al. Comparative Acute Toxicity of Diethylene Glycol, Ethylene

Glycol, and Propylene Glycol to Freshwater and Marine Fish, Invertebrates, and

Algae. ARCO Chemical Company, 1992.
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents

9-31

13. Cowgill, U.M. et al. A Comparison of the Effect of Four Benchmark Chemicals

on Daphnia Magna and Ceriodaphnia Dubia Affinis Tested at Two Different

Temperatures. Environmental Toxicology and Chemistry, Volume 4(3), 1985.

14. Budavari, S., ed. The Merck Index., Twelfth Edition. Merck & Co., Inc.

Whithouse Station, NJ., 1996.

15. Cancilla, D. et al. Isolation and Characterization of Microtox®-Active

Components from Aircraft De-Icing/Anti-Icing Fluids. Environmental Toxicology

and Chemistry, Volume 16(3), 1997 (DCN T10467).

16. D.W.A. Sharp Dictionary of Chemistry. 1990. 

17. U.S.A.F. Air Combat Command. Literature and Technology Review Report for

Aircraft and Airfield Deicing. September 1997 (DCN T10450).

18. Material Safety Data Sheets for Aircraft Deicing/Anti-icing Fluids. (DCN

T10515).

19. Letter from Nancy Diebler Wesselman, Union Carbide Corporation to David

Hoadley, U.S. EPA. May 6, 1999 (DCN T10548).

20. Letter from Stephen Kramer, Octagon Process Inc., to Shari Zuskin, U.S. EPA. 

April 26, 1999 (DCN T10543).

21. Cornell, J. et al. Comparative Measures of the Toxicity of Deicing Fluid

Components. 1999 (DCN T10607). 

22. Arco Chemical Company. Summary Report for Glycol Biodegradability Testing

Program. April 1990 (DCN T10383).

23. Verschueren, K. Handbook of Environmental Data on Organic Chemicals., Third

Edition. 1996. 

24. NTP Chemical Repository for Diethylene Glycol (DCN T10571).

25. “Epidemic of Pediatric Deaths from Acute Renal Failure Caused by Diethylene

Glycol Poisoning,” The Journal of the American Medical Association. April 15,

1998 (DCN T10570).

26. National Heath Institute. Teratology: Diethylene Glycol in CD-1 Mice (Abstract).

(DCN T10569). 

27. Aldrich Catalog Handbook of Fine Chemicals. 1996-1997.
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents

9-32

28. U.S. Environmental Protection Agency. Draft Cleaner Technologies Substitutes

Assessment (CTSA): Screen Reclamation (EPA 744R-94-005a). September 1994.

29. NTP Chemical Repository for Isopropanol (DCN T10572).

30. U.S. Environmental Protection Agency. International Screening Information Data

Sets (SIDS). 1997.

31. Material Safety Data Sheets and Product Specifications for Runway Deicers (DCN

T10586).

32. Sills, R.D., and P.A. Blakeslee. Environmental Impact of Deicers in Airport

Stormwater Runoff. 1992.

33. Clersceri, L.S., A.E. Greenberg, and R.R. Trussell. Standard Methods for the

Examination of Water and Wastewater. 1989.

34. Mayer, F.L. and M.R. Ellersieck. Manual of Acute Toxicity: Interpretation and

Database for 410 Chemicals and 66 Species of Freshwater Animals. U.S. Fish and

Wildlife Service, 1986.

35. Beak Consultants. Chemical Substance Testing Final Study Reports. Prepared for

Miller Thomson, Barristers & Solicitors, 1995a-h.

36. Johnson, W.W. and M.T. Finley. Handbook of Acute Toxicity of Chemicals to

Fish and Aquatic Invertebrates. U.S. Fish and Wildlife Service, 1980.

37. Pillard, D. A. “Comparative Toxicity of Formulated Glycol Deicers and Pure

Ethylene and Propylene Glycol to Ceriodaphnia Dubia and Pimephales Promelas.” 

Environmental Toxicology and Chemistry, Volume 14, 1995.

38. Mayes, M.A. et al. “A Study to Assess the Influent of Age on the Response of

Fathead Minnows in Static Acute Toxicity Tests.” Bulletin of Environmental

Contamination and Toxicology, Volume 31, 1983.

39. Bridie, A.L. et al. “The Acute Toxicity of Some Petrochemicals to Goldfish.” 

Water Resources, Volume 13, 1979.

40. Lilius, H. et al. “A Comparison of the Toxicity of the Toxicity of 30 Reference

Chemicals to Daphnia Magna and Daphnia Pulex.” Environmental Toxicology and

Chemistry. Volume 14, 1995.
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents

9-33

41. Kuhn, R. et al. “Results of the harmful Effects of Selected Water Pollutants

(Anilines, Phenols, Aliphatic Compounds) to Daphnia Magna.” Water Resources,

Volume 23, 1989.

42. DuFresne, D. And D. Pillard. Relative Toxicities of Formulated Aircraft Deicers

and Pure Glycol Products to Duckweed (Lemna Minor). SETAC World

Congress, 1995.

43. Konemann, H. “Quantitative Structure-Activity Relationships in Fish Toxicity

Studies. Part 1: Relationship for 50 Industrial Pollutants.” Toxicology, Volume

19, 1981.

44. DeZwart, D. And W. Sloof. “Toxicity of Mixtures of Heavy Metals and

Petrochemicals to Xenopus laevis.” Bulletin of Environmental Contamination and

Toxicology, Volume 38, 1987.

45. Gersich, F.M. et al. “The Precision of Daphnid (Daphnia Magna Straus, 1820)

Static Acute Toxicity Tests.” Archives of Environmental Contamination and

Toxicology, Volume 15, 1986.

46. Hermens, J.H. et al. “Quantitative Structure-Activity Relationships and Toxicity

Studies of Mixtures of Chemicals with Anaesthetic Potency: Acute Lethal and

Sublethal Toxicity to Daphnia Magna.” Aquatic Toxicology (AMST), Volume 5,

1984. 

47. Calleja, M.C. et al. “Comparative Acute Toxicity of the First 50 Multicentre

Evaluation of In Vitro Cytoxicity Chemicals to Aquatic Non-Vertebrates.” 

Archives of Environmental Contamination and Toxicology, Volume 26, 1994.

48. Bringmann, G. and R. Kuhn. “Results of Damaging Effect of Water Pollutants on

Daphnia Magna.” Z. Wasser Abwasser Forsch, Volume 10(5), 1977.

49. Aeroports de Montreal and Analex Inc. Evaluation des Operations de Degivrage

et Impacts Environmentaux. 1995.

50. Aeroports de Montreal and Analex Inc. Characterization Ecotoxicologique de

Liquides Degivrants et Antigivrants pour Avions Utilises aux Aeroports de

Montreal. 1994.

51. Ward, T.J. and R.L. Boeri. “Toxicity of Ethylene Glycol to the Saprozoic

Flagellate, Chilomonas Paramecium.” Study Number 188-AD for Air Canada. 

1993.

52. Price K.S. et al. “Brine Shrimp Bioassay and Seawater BOD of Petrochemicals.” 

Journal of the Water Pollution Control Federation, Volume 46, 1974.
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents

9-34

53. Blackman, R.A. “Toxicity of Oil-Sinking Agents.” Marine Pollution Bulletin,

Volume 5, 1974.

54. Akesson, B. Phryotrocha Labronica as Test Animal for the Study of Marine

Pollution. 1970.

55. Majewski, H.S. et al. “Acute Lethality, and Sub-Lethal Effects of Acetone,

Ethanol, and Propylene Glycol on the Cardiovascular and Respiratory Systems of

Rainbow Trout (Salmo Gairdneri).” Water Resources, Volume 13, 1978.

56. Tarkpea, M. et al. “Comparison of the Microtox Test with the 96-hour LC50 Test

for the Harpacticoid Nitocra Spinies.” Ecotoxicology and Environmental Safety,

Volume 11, 1986.

57. Wills, J.H. et al. “Inhalation of Aerosolized Ethylene Glycol by Man.” Clinical

Toxicology, Volume 7(5), 1974.

58. Gordon, H.L. and J.M. Hunter. “Ethylene Glycol Poisoning: A Case Report.” 

Anaesthesia, Volume 17, 1982.

59. Siew, S. et al. “Investigation of “Crystallosis” in Ethylene Glycol Toxicity.” 

Scanning Electron Microscopy, Volume 8, 1975.

60. Walton, E.W. “An Epidemic of Antifreeze Poisoning.” Medicine, Science, and

Law. Volume 18(4), 1978.

61. Cheng, J.T. et al. “Clearance of Ethylene Glycol by Kidneys and Hemodialysis.” 

Journal of Toxicology and Clinical Toxicology, Volume 25(1-2), 1987.

62. Heckerling , P.S. “Ethylene Glycol Poisoning with a Normal Anion Gap due to

Occult Bromide Intoxication.” Annals of Emergency Medicine, Volume 16(12),

1987.

63. Parry, M.F. and R. Wallach. “Ethylene Glycol Poisoning.” American Journal of

Medicine, Volume 57(1), 1974.

64. Peterson, C.D. et al. “Ethylene Glycol Poisoning: Pharmacokinetics During

Therapy with Ethanol and Hemodialysis.” New England Journal of Medicine,

Volume 304, 1981.

65. Spillane, L. et al. “Multiple Cranial Nerve Deficits after Ethylene Glycol

Poisoning.” Annals of Emergency Medicine, Volume 20(2), 1991.
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents

9-35

66. Mallya, K.B. et al. “Bilateral Facial Paralysis Following Ethylene Glycol

Ingestion.” Canadian Journal of Neurological Science, Volume 13(4), 1986.

67. Blakeley, K.R. et al. “Survival of Ethylene Glycol Poisoning with Profound

Acidemia.” New England Journal of Medicine, Volume 328(7), 1993.

68. Commens, C.A. “Topical Propylene Glycol and Hyperosmolarity.” British

Journal of Dermatology, Volume 122(1), 1990.

69. Fligner, C.L. et al. “Hyperosmolality Induced by Propylene Glycol: A

Complication of Silver Sulfadiazine Therapy.” Journal of the American Medical

Association, Volume 253(11), 1985.

70. Hunnuksela, M. et al. “Skin Reactions to Propylene Glycol.” Contact Dermatitis,

Volume 1, 1975. 

71. Kinnunen, T. and M. Hannuksela. “Skin Reactions to Hexylene Glycol.” Contact

Dermatitis, Volume 21(3), 1989.

72. Trancik, R.J. and H.I. Maiback. “Propylene Glycol Irritation or Sensitization?” 

Contact Dermatitis, Volume 8, 1982.

73. Warshaw, T.G. and F. Herrmann. “Studies of Skin Reactions to Propylene

Glycol.” Journal of Investigative Dermatology, Volume 19, 1952.

74. Willis, C.M. et al. “Experimentally-Induced Irritant Contact Dermatitis:

Determination of Optimum Irritant Concentrations.” Contact Dermatitis, Volume

18(1), 1988.

75. Willis, C.M. et al. “Epidermal Damage Induced by Irritants in Man: A Light and

Electron Microscopic Study.” Journal of Investigative Dermatology, Volume

93(5), 1989.

76. Ward, T. Comparative Acute Toxicity of Type I and Type II Deicing and

Antiicing Fluids to Freshwater and Marine Fish, Invertebrates, and Algae.

Prepared for ARCO Chemical Company, 1994.

77. Hartwell, S.I. et al. Toxicity of Aircraft De-Icer and Anti-Icer Solutions to

Aquatic Organisms. Maryland Department of Natural Resources, 1993 and

Environmental Toxicology and Chemistry, Volume 14, 1995.

78. HydroQual Laboratories. Daphnia Magna (Waterflea) 48h Static Acute Lethality

Test. Project#: 94030-1 for AGRA Earth and Environmental Sciences. 1994.
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents

9-36

79. Geiger, D.L. et al. Acute Toxicities of Organic Chemicals to Fathead Minnows

(Pimephales Promelas). Center for Lake Superior Environmental Studies. 

Volume 5, 1990.
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents

9-37

Table 9-1

Acute and Chronic Toxicity Data for Pure Glycols for Aquatic Species

Species Endpoint Stage (E C) Glycol (mg/L) Glycol (mg/L) Reference

Duration and Life Temp. Pure Ethylene Pure Propylene

Concentration of Concentration of

Rainbow Trout 24-h LC 0.64 g 12 65,100 (12) 79,700 (12) Ward et al. 1992 (12)

(Oncorhynchus

mykiss)

50

48-h LC 0.64 g 12 54,500 (12) 79,700 (12) Ward et al. 1992 (12) 50

72-h LC 0.64 g 12 54,500 (12) 51,600 (12) Ward et al. 1992 (12) 50

96-h LC 0.3 - 5 g 12 - 15 50,800 (12) 51,600 (12) Ward et al. 1992 (12) 50

45,600 (34) 45,600 (34) Mayer and Ellersieck

17,800 (34) 1986 (34)

22,810 (35) 42,380 (35) Beak Consultants 1995

24,591 (35) 37,067 (35) (35)

41,000 (36) Johnson and Finley

1980 (36)

Fathead 24-h LC 0.3 g 22 83,400 (12) 77,800 (12) Ward et al. 1992 (12)

Minnow

(Pimephales

promelas)

50

48-h LC 0.3 g 22 52,300 (12) 54,000 (12) Ward et al. 1992 (12) 50

48-h LC #7 d old 25 81,950 (37) > 62,000 (37) Pillard 1995 (37) 50

72-h LC 0.3 g 22 52,300 (12) 51,400 (12) Ward et al. 1992 (12) 50

96-h LC 0.3 - 0.4 g 21 -23 50,400 (12) 51,400 (12) Ward et al. 1992 (12) 50

57,000 (38) Mayes et al. 1983 (38)

96-h LC #7 d old 25 72,860 (37) 55,770 (37) Pillard 1995 (37) 50

96-h NOEC #7 d old 25 39,140 (37) 52,930 (37) Pillard 1995 (37)

(mortality)

7-d NOEC #7 d old 25 32,000 (37) < 11,530 (37) Pillard 1995 (37)

(mortality)

7-d NOEC #7 d old 25 15,380 (37) < 11,530 (37) Pillard 1995 (37)

(growth)

Goldfish 24-h LC 6.2 cm 20 >5,000 (39) >5,000 (39) Bridie et al 1979 (39)

(Carassius

auratus)

50

3.3 g

Clawed Frog 48-h LC 3-4 weeks 20.0- 19,350 (35) 18,700 (35) Beak Consultants 1995

(Xenopus

laevis)

50

old 20.5 15,667 (35) 24,285 (35) (35)

Water Flea 24-h LC <24 h old 20 80,600 (12) 70,700 (12) Ward et al. 1992 (12)

(Daphnia

magna)

50

(0.19 mg)

24-h EC <24 h old 20 48,582 (40) Lilius et al 1995 (40) 50

(immobilization) >10,000 (41) Kuhn et al 1989 (41)

48-h LC <24 h old 20 54,700 (12) 43,500 (12) Ward et al. 1992 (12) 50

(0.19 mg) 46,300 (13) Cowgill et al 1985 (13)

51,100 (13)
Table 9-1 (Continued)

Section 9.0 - Toxicity of Deicing/Anti-Icing Agents

Species Endpoint Stage (E C) Glycol (mg/L) Glycol (mg/L) Reference

Duration and Life Temp. Pure Ethylene Pure Propylene

Concentration of Concentration of

9-38

Ceriodaphnia

dubia

48-h LC <24 h old 25 34,440 (37) 18,340 (37) Pillard 1995 (37) 50

48-h NOEC <24 h old 25 24,000 (37) 13,020 (37) Pillard 1995 (37)

7-d NOEC <24 h old 25 24,000 (37) 29,000 (37) Pillard 1995 (37)

(mortality)

7-d NOEC <24 h old 25 8,590 (37) 13,020 (37) Pillard 1995 (37)

(reproduction) 3,469 (35) Beak Consultants 1995

(35)

Green Algae 24-h EC 1,000 24 <6,400 (12) 5,200 (12) Ward et al. 1992 (12)

(Selenastrum

capricornutum)

50

cells/mL

48-h EC 1,000 24 13,100 (12) 34,100 (12) Ward et al. 1992 (12) 50

cells/mL

72-h EC 1,000 24 <6,400 (12) 24,200 (12) Ward et al. 1992 (12) 50

cells/mL

96-h EC 1,000 24 7,900 (12) 19,000 (12) Ward et al. 1992 (12) 50

cells/mL

14-d EC 1,000 24 18,200 (12) 18,100 (12) Ward et al. 1992 (12) 50

cells/mL

96-h IC50 NR 25 13,067 (35) 20,690 (35) Beak Consultants 1995

(35)

96-h IC25 NR 25 8,828 (35) 1,516 (35) Beak Consultants 1995

(35)

96-h LOEC NR 25 13,925 (35) 126 (35) Beak Consultants 1995

(35)

96-h NOEC NR 25 6,963 (35) 37 (35) Beak Consultants 1995

(35)

96-h IC NR 25 5,336 (42) 20,800 (42) DuFresne and Pillard 25

1995 (42)

Duckweed 96-h IC (frond 5 plants/ 25 17,115 (42) 12,000 (42) DuFresne and Pillard

(Lemna minor)

25 

growth) beaker 1995 (42)

96-h LOEC 5 plants/ 25 10,000 (42) 5,000 (42) DuFresne and Pillard

(frond growth) beaker 1995 (42)

 96-h IC25 5 plants/ 25 19,848 (42) 21,882 (42) DuFresne and Pillard

(chlorophyll) beaker 1995 (42)

 96-h LOEC 5 plants/ 25 20,000 (42) 20,000 (42) DuFresne and Pillard

(chlorophyll) beaker 1995 (42)

 96-h IC25 5 plants/ 25 16,470 (42) 12,000 (42) DuFresne and Pillard

(pheophytin) beaker 1995 (42)
Table 9-1 (Continued)

Section 9.0 - Toxicity of Deicing/Anti-Icing Agents

Species Endpoint Stage (E C) Glycol (mg/L) Glycol (mg/L) Reference

Duration and Life Temp. Pure Ethylene Pure Propylene

Concentration of Concentration of

9-39

Duckweed 96-h LOEC 5 plants/ 25 40,000 (42) 20,000 (42) DuFresne and Pillard

(pheophytin) beaker 1995 (42) (cont.)

Sheepshead 24-h LC 0.74 g 22 81,700 (12) 63,500 (12) Ward et al. 1992 (12)

minnow

(Cyprinodon

variegatus)

50

48-h LC 0.74 g 22 74,800 (12) 52,500 (12) Ward et al. 1992 (12) 50

72-h LC 0.74 g 22 39,100 (12) 35,900 (12) Ward et al. 1992 (12) 50

96-h LC 0.74 g 22 27,600 (12) 23,800 (12) Ward et al. 1992 (12) 50

Mysid 24-h LC 2.4 mg 22 73,900 (12) 31,000 (12) Ward et al. 1992 (12)

(Mysidopsis

bahia)

50

48-h LC 2.4 mg 22 52,600 (12) 27,300 (12) Ward et al. 1992 (12) 50

72-h LC 2.4 mg 22 43,600 (12) 23,400 (12) Ward et al. 1992 (12) 50

96-h LC 2.4 mg 22 34,200 (12) 18,800 (12) Ward et al. 1992 (12) 50

Marine algae 24-h EC 1,000 20 <6,900 (12) 31,500 (12) Ward et al. 1992 (12)

(Skeletonema

costatum)

50

cells/mL

48-h EC 1,000 20 23,900 (12) 19,000 (12) Ward et al. 1992 (12) 50

cells/mL

72-h EC 1,000 20 29,900 (12) 19,300 (12) Ward et al. 1992 (12) 50

cells/mL

96-h EC 1,000 20 44,200 (12) 19,100 (12) Ward et al. 1992 (12) 50

cells/mL

14-d EC 1,000 20 <5,300 (12) <5,300 (12) Ward et al. 1992 (12) 50

cells/mL

LC - Median lethal concentration that kills 50% of the test organisms. 50

NOEC - No-observed-effect concentration. 

EC - The median effective concentration. The concentration of a substance that causes a specified effect (generally sublethal 50

rather than acutely lethal) in 50% of the test organisms.

IC - Concentration that inhibits growth and reproduction in 25% of the test organisms. 25 

LOEC - Lowest concentration at which effects were observed.

( ) - Reference for the data provided.
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents

9-40

Table 9-2

Additional Acute and Chronic Toxicity Data Sources for Pure Glycols

Pure Glycol Type Species Reference

Ethylene Glycol Rainbow trout Beak Consultants 1995 (35)

(Oncorhynchus mykiss)

Fathead minnow (Pimephales

promelas)

Mayes et al. 1983 (38)

Beak Consultants 1995 (35)

Bluegill sunfish (Lepomis

macrochirus)

Mayer and Ellersieck 1986

(34)

Abdelghani et al. 1990 (12)

Guppy (Poecillia reticulata) Konemann 1981 (43)

Clawed frog (Xenopus laevis) deZwart and Slooff 1987 (44)

Water flea (Daphnia magna) Gersich et al. 1986 (45)

Hermens et al. 1984 (46)

Calleja et al. 1994 (47)

Bringmann and Kuhn 1977

(48)

Water flea (Daphnia pulex) Lilius et al. 1995 (40)

Ceriodaphnia dubia Cowgill et al. 1985 (13)

Pillard 1995 (37)

Beak Consultants 1995 (35)

Streptocephalus probscideus Calleja et al. 1994 (47)

Chironomus tentans Aeroports de Montreal 1995

(49)

Crayfish (Procambarus sp.) Abdelghani et al. 1990 (12)

Rotifer (Brachionus

calciflorus)

Beak Consultants 1995 (35)

Calleja et al. 1994 (47)

Ciliated protozoan Beak Consultants 1995 (35)

(Colpidium campylum)
Table 9-2 (Continued)

Section 9.0 - Toxicity of Deicing/Anti-Icing Agents

Pure Glycol Type Species Reference

9-41

Ethylene Glycol (con’t.) Green algae (Selenastrum Aeroports de Montreal and

capricornutum) Analex Inc. 1994 (50)

Criptomonad (Chilomonas

paramecium)

Ward and Boeri 1993 (51)

Brine shrimp (Artemia salina) Price et al. 1974 (52)

Shrimp (Crangon crangon) Blackman 1974 (53)

Polychaeta (Ophrytrocha

labronica)

Akesson 1970 (54)

Propylene Glycol Rainbow trout Majewski et al. 1978 (55)

(Oncorhynchus mykiss)

Fathead minnow (Pimephales

promelas)

Pillard 1995 (37)

Water flea (Daphnia magna) Kuhn et al. 1989 (41)

Ceriodaphnia dubia Pillard 1995 (37)

Green algae (Selenastrum

capicornutum)

Dufresne and Pillard 1995 (42)

Duckweed (Lemna minor) Dufresne and Pillard 1995 (42)

Harpaticoid copepod (Nitocra

spinipes)

Tarkpea et al. 1986 (56)

 ( ) - Reference for the data provided.
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents

9-42

Table 9-3

Human Toxicity Data for Pure Ethylene Glycol and Propylene Glycol

Exposure Duration/ LOAEL and

Type Health Effect Frequency NOAEL Seriousness Reference

Exposure/

Inhalation Ethylene Glycol

Systemic - 15 min. 55 mg/L (less Wills et al. 1974 (57)

Respiratory serious)

Systemic - 30 days (20- 19 mg/L Wills et al. 1974 (57)

Hematological 22 hrs/day)

Systemic - Renal 30 days (20- 19 mg/L Wills et al. 1974 (57)

22 hrs/day)

Neurological 30 days (20- 19 mg/L (less Wills et al. 1974 (57)

22 hrs/day) serious)

Oral Ethylene Glycol

(ingestion)

Death Once 7,070 mg/kg/d Gordon and Hunter

(serious) 1982 (58)

Once 4,071 mg/kg/d Siew et al. 1975 (59)

(serious)

Once 2,379 mg/kg/d Walton 1978 (60)

(serious)

Once 1,559 mg/kg/d Verschueren 1983 (23)

(serious)

Systemic - Once 4,332 mg/kg/d Cheng et al. 1987 (61)

Metabolism (serious)

Once 7,070 mg/kg/d Gordon and Hunter 

(serious) 1982 (58)

Once 11,238 mg/kg/d Heckerling 1987 (62)

(serious)

Once 3,171 mg/kg/d Parry and Wallach 

(serious) 1974 (63)

Once 7,600 mg/kg/d Peterson et al. 1981

(serious) (64)

Once 4,071 mg/kg/d Siew et al. 1975 (59)

(serious)

Once 12,839 mg/kg/d Spillane et al. 1991

(serious) (65)

Systemic - Once 7,070 mg/kg/d Gordon and Hunter

Respiratory (less serious) 1982 (58)
Table 9-3 (Continued)

Section 9.0 - Toxicity of Deicing/Anti-Icing Agents

Exposure Duration/ LOAEL and

Type Health Effect Frequency NOAEL Seriousness Reference

Exposure/

9-43

Oral (cont.) Systemic - Once 7,070 mg/kg/d Gordon and Hunter

Cardiovascular (serious) 1982 (58)

Once 3,171 mg/kg/d Parry and Wallach

(serious) 1974 (58)

Once 4,071 mg/kg/d Slew et al. 1975 (59)

(serious)

Systemic - Renal Once 7,070 mg/kg/d Gordon and Hunter

(serious) 1982 (58)

Once 11,238 mg/kg/d Heckerling 1987 (62)

(serious)

Once 2,714 mg/kg/d Mallya et al. 1986 (66)

(serious)

Once 3,171 mg/kg/d Parry and Wallach

(serious) 1974 (63)

Once 7,600 mg/kg/d Peterson et al. 1981

(serious) (64)

Once 4,071 mg/kg/d Slew et al. 1975 (59)

(serious)

Once 12,839 mg/kg/d Spillane et al. 1991

(serious) (65)

Systemic - Once 12,839 mg/kg/d Spillane et al. 1991

Gastrointestinal (serious) (65)

Neurological Once 9,771 mg/kg/d Blakeley et al. 1993

(serious) (67)

Once 4,332 mg/kg/d Cheng et al. 1987 (61)

(serious)

Once 7,070 mg/kg/d Gordon and Hunter

(less serious) 1982 (58)

Once 11,238 mg/kg/d Heckerling 1987 (62)

(serious)

Once 2,714 mg/kg/d Mallya et al. 1986 (66)

(serious)

Once 3,171 mg/kg/d Parry and Wallach

(serious) 1974 (63)

Once 4,071 mg/kg/d Slew et al. 1975 (59)

(serious)

Once 12,839 mg/kg/d Spillane et al. 1991

(serious) (65)
Table 9-3 (Continued)

Section 9.0 - Toxicity of Deicing/Anti-Icing Agents

Exposure Duration/ LOAEL and

Type Health Effect Frequency NOAEL Seriousness Reference

Exposure/

9-44

Dermal Propylene Glycol

Systemic - 5 days 6,100 mg/kg Commens 1990 (68)

Hematological (1x/day)

Systemic - 70 hr 9,000 mg/kg Fligner et al. 1985 (69)

Respiratory (>1x/d) (serious)

Systemic - 70 hr 9,000 mg/kg Fligner et al. 1985 (69)

Cardiovascular (>1x/d) (serious)

Systemic - 70 hr 9,000 mg/kg Fligner et al. 1985 (69)

Metabolism (>1x/d) (serious)

Systemic - 20-24 hours 3.2% (less Hannuksela et al. 1975

Dermal serious) (70)

48 hours 10 mg (less Kinnunen and

once serious) Hannuksela 1989 (71)

48 hours 0.2 mg (less Kinnunen and

once serious) Hannuksela 1989 (71)

7 days 104 mg Trancik and Malbach

(2x/day) 1982 (72)

48 hours 2.5% (less Warshaw and

once serious) Herrmann 1952 (73)

48 hours 15 mg 31 mg (less Willis et al. 1988 (74)

once serious)

48 hours 16 mg (less Willis et al. 1989 (75)

once serious)

Systemic - 21-22 days 207 mg (less Trancik and Maibach

Dermal serious) 1982 (72)

Immunological/ 20-24 hours 3.2% (less Hannuksela et al. 1975

Lymphoreticular serious) (70)

Neurological 70 hours 9,000 mg/kg Fligner et al. 1985 (69)

(>1x/day) (serious)

Note: No human toxicological data are available for inhalation and oral exposure to propylene glycol and dermal

exposure to ethylene glycol.

NOAEL - No-observable-adverse-effect-level.

LOAEL - Lowest-observable-adverse-effect-level.

Serious - Effects that evoke failure in a biological system and can lead to morbidity or mortality.

Less Serious - Effects not expected to cause significant dysfunction or death.

( ) - Reference for the data provided.
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents

9-45

Table 9-4

Acute Toxicity Data for Type I and II Formulated Fluids

Species Endpoint Type Stage (E C) (mg/L) (mg/L) Reference

Duration Ethylene Glycol Propylene Glycol

and Fluid Life Temp. Formulated Fluid Formulated Fluid

Concentration of Concentration of

Fathead 96-h LC I #14 d 20-25 12,000 (76) 4,900(76) Ward 1994 (76)

Minnow 10,635 (35) 1,588(35) Beak Consultants 1995

(Pimephales

promelas)

50

(35)

7-d NOEC I #7 d 25 6,090 (37) 270 (37) Pillard 1995 (37)

(mortality)

7-d NOEC I #7 d 25 <3,330 (37) 98 (37) Pillard 1995 (37)

(growth)

7-d IC I #7 d 25 3,660 (37) 110 (37) Pillard 1995 (37) 25

(growth)

48-h LC I #7 d 25 8,540 (37) 790 (37) Pillard 1995 (37) 50

48-h LC I #60 d 21 10,940 (77) Hartwell et al. 50

1993,1995 (77)

96-h LC I #60 d 21 10,940 (77) Hartwell et al. 50

1993,1995 (77)

7-d LC I #60 d 21 10,940 (77) Hartwell et al. 50

1993,1995 (77)

96-h LC I #7 d 25 8,050 (37) 710 (37) Pillard 1995 (37) 50

96-h LC II #7 d 21-25 210 (76) 100 (76) Ward 1994 (76) 50

18 (77) Hartwell et al. 1993,

1994 (77)

48-h LC II #7 d 22 - 25 42 (77) Hartwell et al. 50

1993,1995 (77)

7-d LC II #7 d 22 18 (77) Hartwell et al. 50

1993,1995 (77)

Rainbow Trout 96-h LC I 0.3- 15 10,635 (35) 2,096 (35) Beak Consultants 1995

(Oncorhynchus

mykiss)

50

5.0 g (35)

96-h LC I juvenile 12 3,700 (76) 3,200 (76) Ward 1994 (76) 50

96-h LC II juvenile 11-12 200 (76) 38 (76) Ward 1994 (76) 50
Table 9-4 (Continued)

Section 9.0 - Toxicity of Deicing/Anti-Icing Agents

Species Endpoint Type Stage (E C) (mg/L) (mg/L) Reference

Duration Ethylene Glycol Propylene Glycol

and Fluid Life Temp. Formulated Fluid Formulated Fluid

Concentration of Concentration of

9-46

Ceriodaphnia

dubia

7-d NOEC I <24 h 25 8,400 (37) 660 (37) Pillard 1995 (37)

(mortality)

7-d NOEC I <24 h 25 <3,330 (37) 600 (37) Pillard 1995 (37)

(reprod.)

7-d IC I <24 h 25 3,960 (37) 640 (37) Pillard 1995 (37) 25

48-h LC I <24 h 25 13,140 (37) 1,020 (37) Pillard 1995 (37) 50

48-h EC I <24 h 21 7,730 (77) Hartwell et al. 50

1993,1995 (77)

96-h EC I <24 h 21 5,384 (77) Hartwell et al. 50

1993,1995 (77)

7-d EC I <24 h 21 1,817 (77) Hartwell et al. 50

(reprod.) 1993,1995 (77)

Water Flea 48-h LC I <24h 20 26,185 (35) 4,192 (35) Beak Consultants 1995

(Daphnia

magna)

50

(35)

48-h EC I <24h 20-21 7,100 (76) 6,000 (76) Ward 1994 (76) 50

48-h EC II <24h 19-21 120 (76) 280 (76) Ward 1994 (76) 50

Sheepshead 96-h LC I juvenile 22 19,000 (76) 7,000 (76) Ward 1994 (76)

Minnow

(Cyprinodon

variegatus)

50

96-h LC II juvenile 21-23 270 (76) 290 (76) Ward 1994 (76) 50

Mysid 96-h LC I <24h 23-26 1,100 (76) 1,800 (76) Ward 1994 (76)

(Mysidopsis

bahia)

50

96-h LC II <24h 24-25 29 (76) 390 (76) Ward 1994 (76) 50

Marine algae 96-h LC I 10,000 20-24 1,200 (76) 510 (76) Ward 1994 (76)

(Skeletonema

costatum)

50

cells/m

L

96-h LC II 10,000 19-21 7 (76) 29 (76) Ward 1994 (76) 50

cells/m

L

LC - Median lethal concentration that kills 50% of the test organisms. 50

EC - The median effective concentration. The concentration of a substance that causes a specified effect (generally sublethal 50

rather than acutely lethal) in 50% of the test organisms.

( ) - Reference for the data provided.
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents

9-47

Table 9-5

Additional Aquatic Toxicity Data Sources for 

Formulated Fluids

Glycol and Fluid Type Species Reference

Ethylene Glycol Type I Daphnia pulex Hartwell et al. 1993; 1995 (77)

Water flea (Daphnia magna) HydroQual Laboratories 1994 (78)

Hartwell et al. 1993; 1995 (77)

Chironamus tentans Aeroports de Montreal & Analex

1995 (49)

Green algae (Selenastrum

capricornutum)

Ward 1994 (76)

Aeroports de Montreal & Analex

1995 (49)

Ethylene Glycol Type II Chironamus tentans Aeroports de Montreal & Analex

1995 (49)

Green algae (Selenastrum

capricornutum)

Aeroports de Montreal & Analex

1994 (50)

Ward 1994 (76)

Propylene Glycol Type I Green algae (Selenastrum Ward 1994 (76)

capicornutum)

Propylene Glycol Type II Daphnia magna Hartwell et al. 1993; 1995 (77)

Daphnia pulex Hartwell et al. 1993; 1995 (77)

Green algae (Selenastrum

capicornutum)

Ward 1994 (76)

 ( ) - Reference for the data provided.
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents

9-48

Table 9-6

Aquatic Toxicity Results for Formulated Fluids and Their Components

Species Solution (mg/L) Duration (mg/L) (mg/L)

Concentrations of Concentration Concentration

Solution Tested measured as measured as 

PG/TTZ/Adpack PG TTZ

Ceriodaphnia

dubia

PG + TTZ 10,000/600/0 48-h LC50 1,647 98

10,000/120/0 48-h LC50 8,770 109

20,000/110/0 48-h LC50 11,842 68

TTZ only 0/150/0 48-h LC50 NA 108

0/180/0 48-h LC50 NA 102

PG only 31,000/0/0 48-h LC50 15,052 NA

Fully 5,000/31/P 48-h LC 3,829 24

formulated

fluid

a

50

9,400/52/P 48-h LC 3,224 18 b

50

PG + 10,000/0/P 48-h LC 5,122 NA

additive

pack

c

50

11,000/0/P 48-h LC 4,919 NA d

50

Fathead PG + TTZ 10,000/120/0 96-h LC 3,566 43

minnow

(Pimephales

promelas)

50

20,000/110/0 96-h LC50 6,742 39

TTZ only 0/150/0 96-h LC50 NA 38

0/190/0 96-h LC50 NA 65

PG only 99,000/0/0 96-h LC50 34,060 NA

Fully 5,000/28/P 96-h LC 1,716 10

formulated

fluid

a

50

9,000/52/P 96-h LC 1,525 8

b

50

PG + 10,000/0/P 96-h LC 1,434 NA

additive

pack

c

50

11,000/0/P 96-h LC 1,866 NA d

50

Microtox® PG + TTZ 10,000/58/0 15-min EC50 1,127 6

10,000/600/0 15-min EC50 153 9

TTZ only 0/48/0 15-min EC50 NA 7

PG only 10,000/0/0 15-min EC50 5,650 NA
Table 9-6 (Continued)

Section 9.0 - Toxicity of Deicing/Anti-Icing Agents

Species Solution (mg/L) Duration (mg/L) (mg/L)

Concentrations of Concentration Concentration

Solution Tested measured as measured as 

PG/TTZ/Adpack PG TTZ

9-49

Microtox® Fully 10,000/61/P 15-min EC 950 6

(cont.) formulated

fluid

a

50

9,400/52/P 15-min EC 1,497 8

b

50

PG + 10,000/0/P 15-min EC 5,247 NA

additive

pack

c

50

Source: Reference (15).

PG - propylene glycol.

TTZ - 4-methyl-benzotriazole and 5-methyl-benzotriazole (common name: tolyltriazole).

NA - Not applicable.

LC - Lethal concentration that kills 50% of the test organisms. 50

EC50 - The median effective concentration. The concentration of a substance that causes a specified effect (generally

P - Present at an unknown concentration (proprietary information) from Manufacturer 1 (TTZ present). a 

P - Present at an unknown concentration (proprietary information) from Manufacturer 2 (TTZ present). b 

P - Present at an unknown concentration (proprietary information) from Manufacturer 1 (without TTZ). c

P - Present at an unknown concentration (proprietary information) from Manufacturer 2 (without TTZ). d 
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents

9-50

Table 9-7

Aquatic Toxicity Data for Diethylene Glycol 

Species Endpoint Life Stage (E C) (mg/L) Reference

Duration & Temp. Diethylene Glycol

Concentration of

Rainbow trout 24-h LC 4.1 cm & 0.64 g 12 87,100 (12) Ward et al. 1992 (12)

(Oncorhynchus

mykiss)

50

48-h LC 4.1 cm & 0.64 g 12 79,800 (12) Ward et al. 1992 (12) 50

72-h LC 4.1 cm & 0.64 g 12 55,400 (12) Ward et al. 1992 (12) 50

96-h LC 3.5 - 4.1 cm & 0.42 12 - 15 52,800 (12) Ward et al. 1992 (12) 50

- 0.64 g 62,934 (35) Beak Consultants 1995 (35)

Fathead minnow 24-h LC 3.1 cm & 0.3 g 22 86,800 (12) Ward et al. 1992 (12)

(Pimephales

promelas)

50

48-h LC 3.1 cm & 0.3 g 22 86,800 (12) Ward et al. 1992 (12) 50

72-h LC 3.1 cm & 0.3 g 22 86,800 (12) Ward et al. 1992 (12) 50

96-h LC 3.1 cm & 0.3 g 22 84,100 (12) Ward et al. 1992 (12) 50

96-h LC 19.1 mm & 0.102 g 24.9 75,200 (79) Geiger et al. 1990 (79) 50

Guppy (Poecillia

reticulata)

168-h LC 2-3 cm 22 61,000 (43) Konemann 1981 (43) 50

Goldfish 24-h LC 6.2 cm & 3.3 g 20 >5,000 (39) Bridie et al. 1979 (39)

(Carassius

auratus)

50

Clawed toad 48-h LC 3-4 weeks old 20 20,358 (35) Beak Consultants 1995 (35)

(Xenopus laevis)

50

20,496 (35)

3,065 (44) deZwart and Zloof 1987 (44)

Water flea 24-h LC < 24 h old 20 - 22 >10,000 (48) Bringmann and Kuhn 1977 (48)

(Daphnia magna)

50

78,500 (12) Ward et al. 1992 (12)

48-h LC < 24 h old 20 47,200 (12) Ward et al. 1992 (12) 50

Green algae 24-h EC 1,000 cells/mL 24 6,400 (12) Ward et al. 1992 (12)

(Selenastrum

capricornutum)

50

48-h EC 1,000 cells/mL 24 24,000 (12) Ward et al. 1992 (12) 50

72-h EC 1,000 cells/mL 24 6,400 (12) Ward et al. 1992 (12) 50

96-h EC 1,000 cells/mL 24 19,900 (12) Ward et al. 1992 (12) 50

14-d EC 1,000 cells/mL 24 37,000 (12) Ward et al. 1992 (12) 50

Sheepshead 24-h LC 0.74 g 20 90,700 (12) Ward et al. 1992 (12)

minnow

(Cyprinodon

variegatus)

50

48-h LC 0.74 g 20 87,900 (12) Ward et al. 1992 (12) 50

72-h LC 0.74 g 20 79,600 (12) Ward et al. 1992 (12) 50

96-h LC 0.74 g 20 62,100 (12) Ward et al. 1992 (12) 50
Table 9-7 (Continued)

Section 9.0 - Toxicity of Deicing/Anti-Icing Agents

Species Endpoint Life Stage (E C) (mg/L) Reference

Duration & Temp. Diethylene Glycol

Concentration of

9-51

Mysid (Mysidopsis

bahia)

24-h LC 2.4 mg 22 54,900 (12) Ward et al. 1992 (12) 50

48-h LC 2.4 mg 22 43,800 (12) Ward et al. 1992 (12) 50

72-h LC 2.4 mg 22 42,900 (12) Ward et al. 1992 (12) 50

96-h LC 2.4 mg 22 36,900 (12) Ward et al. 1992 (12) 50

Brine shrimp 24-h LC nauplii 24.5 >10,000 (52) Price et al. 1974 (52)

(Artemia salina)

50

Marine algae 24-h EC 1,000 cells/mL 20 8,900 (12) Ward et al. 1992 (12)

(Skeletonema

costatum)

50

48-h EC 1,000 cells/mL 20 26,900 (12) Ward et al. 1992 (12) 50

72-h EC 1,000 cells/mL 20 27,300 (12) Ward et al. 1992 (12) 50

96-h EC 1,000 cells/mL 20 40,800 (12) Ward et al. 1992 (12) 50

14-d EC 1,000 cells/mL 20 22,600 (12) Ward et al. 1992 (12) 50

LC - Median lethal concentration that kills 50% of the test organisms. 50

EC - The median effective concentration. The concentration of a substance that causes a specified effect (generally sublethal 50

rather than acutely lethal) in 50% of the test organisms.

( ) - Reference for the data provided.
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents

9-52

Table 9-8

Mammalian Toxicity Data for Diethylene Glycol

Exposure Type Species Typical Dose Amount Units

Inhalation Mouse Lowest published lethal 130 mg/m /2 hours

concentration

3

Oral Human Lowest published lethal 1,000 mg/kg

dose

Dog LD50 9,000 mg/kg

Guinea pig LD50 7,800 mg/kg

Cat LD50 3,300 mg/kg

Mouse LD50 23,700 mg/kg

Rabbit LD50 4,400 mg/kg

Rat LD50 12,565 mg/kg

Dermal Rabbit Lowest published lethal 2,236 mg/kg

(intravenous) dose

Mouse Lowest published lethal 5,000 mg/kg

(subcutaneous) dose

Rabbit (skin) LD50 11,890 mg/kg

Mouse LD 9,719 mg/kg

(intraperitoneal)

50

Rat (intravenous) LD50 6,565 mg/kg

Rat (subcutaneous) LD50 18,800 mg/kg

Rat LD 7,700 mg/kg

(intraperitoneal)

50

Source: Reference (23).

LD - Median lethal dose that kills 50% of the test organisms. 50
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents

9-53

Table 9-9

Aquatic Toxicity Data for Isopropanol

Species Duration & Endpoint Stage (E C) Isopropanol (mg/L)

Life Temperature Concentration of

Fathead minnow 1-h LC NA NA 11,830

(Pimephales

promelas)

50

24-h LC50 NA NA 11,160

48-h LC50 NA NA 11,130

72-h LC50 NA NA 11,130

96-h LC50 NA NA 11,130

Water flea (Daphnia

magna)

EC50 (reproduction) NA NA 3,010

NOEC (reproduction) NA NA 2,100

NOEC (growth) NA NA 757

24-h LC50 NA NA 9,500

Goldfish (Carassius

auratus)

24-h LC50 NA NA >500

Brown shrimp 48-h LC NA NA 1,400

(Crangon crangon)

50

98-h LC50 NA NA 1,150

Guppy (Poecilia

reticulata)

7-d LC50 NA NA 7,060

Green algae 7-d EC NA NA 1,800

(Scenedesmus

quadricauada)

0

Microtox 5-min EC NA NA 22,800 TM

(Photobacterium) test

50

Source: Reference (20).

LC - Median lethal concentration that kills 50% of the test organisms. 50

NOEC - No-observed-effect concentration. 

EC50 - The median effective concentration. The concentration of a substance that causes a specified effect (generally

sublethal rather than acutely lethal) in 50% of the test organisms.

NA - Not available.
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents

9-54

Table 9-10

Mammalian Toxicity Data for Isopropanol

Exposure Type Species Typical Concentration/Dose Amount Units

Inhalation Rat Lowest published lethal concentration 16,000 mg/m /4 hours 3

Mouse Lowest published lethal concentration 12,800 mg/m /3 hours 3

Oral Human Lowest published toxic dose 223 - 14,432 mg/kg

Lowest published lethal dose 3,570 - 5,272 mg/kg

Rat LD50 5,045 mg/kg

Dog LD50 4,797 mg/kg

Rabbit LD50 6,410 mg/kg

Mouse LD50 3,600 mg/kg

Dermal Rat LD50 (intraperitoneal) 2,735 mg/kg

LD50 (intravenous) 1,088 mg/kg

Dog Lowest published lethal dose (intravenous) 5,120 mg/kg

Cat Lowest published lethal dose (intravenous) 1,963 mg/kg

Rabbit LD50 (skin) 12,800 mg/kg

LD50 (intravenous) 1,184 mg/kg

LD50 (intraperitoneal) 667 mg/kg

Mouse LD50 (intraperitoneal) 4,477 mg/kg

Lowest published lethal dose (subcutaneous) 6,000 mg/kg

LD50 (intravenous) 1,509 mg/kg

Guinea LD (intraperitoneal) 2,560 mg/kg

pig

50 

Hamster LD50 (intraperitoneal) 3,444 mg/kg

Frog Lowest published lethal dose (par) 20,000 mg/kg

Source: Reference (28).

LD - Median lethal dose that kills 50% of the test organisms. 50
Section 10.0 - Environmental Impacts

10-1

10.0 ENVIRONMENTAL IMPACTS FROM THE DISCHARGE OF

DEICING/ANTI-ICING AGENT-CONTAMINATED STORM WATER

Deicing/anti-icing agents enter the environment after they are applied to aircraft

and paved areas, including runways, taxiways, roadways, and gate areas. It is estimated that

approximately 80% of the Type I deicing fluids that are applied to aircraft fall to the pavement

(1). Unless they are captured for recycling, recovery, or treatment (either on site or at a publicly

owned treatment works (POTW)), deicing agents will flow away to be diluted with other runoff

sources or evaporate. If runoff containing deicing agents is not contained or treated, substantial

amounts of deicing/anti-icing chemicals may be released to the ground or discharged, where some

constituents may degrade but others may ultimately contaminate ground or surface waters. Of the

remaining 20% that does not fall to the pavement, an estimated 15% is dispersed to the air while

only 5% remains on the aircraft until it shears off during takeoff.

Anti-icing agents make up a smaller percentage of the contaminated storm water

runoff than deicing agents. This is because the polymers and thickeners that comprise anti-icing

agents make anti-icers more likely to adhere to surfaces and because less volume of fluid is used

as compared to deicing agents. Because of these two factors, anti-icing solutions may also result

in less air emissions (2). However, anti-icing fluids are more likely to be “carried out” on the

plane to runways, which are generally not connected to the airport’s glycol-contaminated

wastewater collection system. Some anti-icing fluid drips off the wings during taxiing, while the

majority shears off the wing during take-off. 

In addition to aquatic and health impacts (discussed in Section 9.0), the

biodegradation of glycols released into the aquatic environment can greatly impact water quality

in receiving streams, including significant reduced oxygen levels. Section 10.1 discusses, where

known, degradability and environmental fate of ethylene glycol and propylene glycol, formulated

aircraft deicing/anti-icing fluids (ADFs), alternate freezing-point depressants, and pavement

deicing agents. This section also describes the potential effects of direct and indirect releases of

aircraft deicing fluids and pavement deicing agents to surface waters and to air. Section 10.2
Section 10.0 - Environmental Impacts

10-2

discusses reports of environmental impacts from the discharge of deicing/anti-icing agentcontaminated storm water. Section 10.3 discusses the effects that the indirect discharge of

deicing/anti-icing agent-contaminated wastewater has on POTWs. All tables are located at the

end of this section.

10.1 Degradability and Environmental Fate of Deicing/Anti-icing Agents

When released to the environment, ADFs and pavement deicers are generally

biodegradable; however, some components require significantly more oxygen to biodegrade than

others. Significant oxygen requirements can reduce oxygen levels in receiving streams to the

point where the streams do not have enough oxygen to support aquatic life. Sections 10.1.1

through 10.1.4 discuss degradability and oxygen demand as well as environmental fate and

bioaccumulation of deicing/anti-icing agents.

10.1.1 Ethylene Glycol and Propylene Glycol

Several environmental effects studies have been performed using pure ethylene

glycol and propylene glycol. Both exert a large oxygen demand when biodegrading, which can

affect aquatic life by depleting available oxygen in a receiving stream. Propylene glycol requires

more oxygen than ethylene glycol to biodegrade (3, 4, 5). 

Propylene glycol is more likely to volatilize to the air following aircraft deicing. 

Both chemicals easily break down in the environment and are not expected to be retained in the

tissue of organisms or increase with continued exposure (i.e., bioaccumulate) (4, 5).

Biodegradation

When released into the environment, both ethylene glycol and propylene glycol are

expected to partition to surface or groundwater. They are expected to rapidly biodegrade and not

to persist in the environment. Biodegradation rates depend on temperature and oxygen conditions
Section 10.0 - Environmental Impacts

10-3

and glycols biodegrade more slowly under anaerobic conditions. The half-life of ethylene glycol

and propylene glycol in water under aerobic and anaerobic conditions, and in soil are shown

below. Note that these data were not conducted under the same laboratory conditions and may

not be directly comparable (5).

Glycol Type Aerobic Conditions Anaerobic Conditions Soil

Half-Life

Aquatic

Ethylene Glycol 2 to 12 days 4 to 48 days 0.2 to 0.9 days (5 - 22 hours)

Propylene Glycol 1 to 4 days 3 to 5 days Equal to or slightly less than in water

Based on data presented in Sections 9.1.1 and 9.1.2, both ethylene glycol and

propylene glycol have a low toxic potential for aquatic and other animal life; however, aquatic life

may be indirectly impacted by the glycol’s rapid biodegradation. The biodegradation of glycols

consumes oxygen and can lead to low oxygen levels in aquatic systems. Anaerobic

biodegradation may also release relatively toxic byproducts such as acetaldehyde, ethanol, acetate,

and methane (6).

While ethylene glycol and propylene glycol are both highly biodegradable, ethylene

glycol requires less oxygen to degrade than propylene glycol, as shown in the following table.

Oxygen Measure Ethylene Glycol Propylene Glycol

Literature values for BOD5 (at 20EC), mg O2/L glycol 400,000 - 800,000 1,000,000

Literature values for BOD5 (at 20EC), g O2/g glycol 0.4 - 0.7 1

Ethylene glycol manufacturer values for theoretical oxygen 1.3 1.7 

demand (i.e., ultimate BOD), g O /g glycol 2

Propylene glycol manufacturer values for average 2.08 2.23

COD:BOD ratio

BOD - 5-day biochemical oxygen demand. 5

COD - Chemical oxygen demand.

Source: References: (3, 4, 7).
Section 10.0 - Environmental Impacts

10-4

In comparison, the BOD of raw domestic sewage is approximately 200 mg of oxygen per liter of 5

sewage while the BOD of treated effluent (discharged to receiving streams) is about 20 mg of 5

oxygen per liter of effluent (8).

Several variables can greatly affect biodegradation rates, such as the quantity of

glycols released, the water temperature, and the chemical and biological quality of the receiving

stream. Glycol biodegradation reduces the normal dissolved oxygen content in the receiving

stream and may cause the oxygen level to fall below the acceptable level for aquatic survival. 

When all of the dissolved oxygen in a stream is used, the stream becomes anaerobic and aquatic

life is threatened. The amount of dissolved oxygen in water decreases with increasing

temperature, and streams are more likely to be threatened by naturally occurring low oxygen

levels in the summer.

In tests performed by a propylene glycol manufacturer, the ultimate BOD was

determined for varying glycol concentrations, temperature, and time using activated sludge

samples that were acclimated to glycols (9). Table 10-1 presents the results of these studies. The

results show that, in general, propylene glycol exerts a higher BOD value (in mg of oxygen per

liter of glycol) than ethylene glycol, except at the lowest concentrations and lowest temperature

tested (1.3 or 3.3 mg/L and 4EC). The results also show that for either glycol, in general, a lower

BOD value is expected at lower temperatures. 

Since most deicing operations occur when temperatures are low, the BOD at 5

20EC test (the typical laboratory test temperature) is an overly conservative estimate of the actual

oxygen demand that would be measured in the receiving stream. However, in early spring when

temperatures may rise and when glycols may be released from melting snow dump piles, the

BOD at 20EC may be a more accurate indicator of what is occurring in the environment. 5

The Streeter-Phelps Model estimates dissolved oxygen (DO) concentrations in a

given stream as a function of time. It may be used to determine a DO deficit following a large

discharge of pollutants that exert a high oxygen demand when biodegrading, such as ethylene
Section 10.0 - Environmental Impacts

10-5

glycol or propylene glycol. The model accounts for temperature, pollutant loading, and rate of

stream flow, but not for other oxygen consumption factors such as additional pollutant loadings

that use oxygen to biodegrade. In one experiment that used the Streeter-Phelps Model, assuming

a 10:1 dilution factor in receiving streams, several iterations and different downstream DO levels

and time periods were used to estimate a maximum ethylene glycol loading upstream to ensure

safe DO levels. The downstream oxygen levels, or “oxygen targets,” are based on guidelines for

protection of cold-water and warm-water species. The results showed that to achieve a final DO

concentration of at least 6.0 mg/L (assumed minimum concentration for warm-water fish), over a

4-hour retention time, less than 800 mg/L of pure ethylene glycol must be in the discharged

effluent. To achieve a final DO concentration of at least 9.5 mg/L (assumed concentration for

cold-water fish), over a 4-hour retention time, less than 300 mg/L of pure ethylene glycol must be

in the discharged effluent. The longer the discharge retention time, the smaller the amount of

glycol that can be discharged without resulting in a DO concentration below the target level. For

example, to achieve a final DO concentration of 9.5 mg/L over a 24-hour retention time, less than

48 mg/L of pure ethylene glycol would be encountered downstream. Therefore, according to the

Streeter-Phelps model, assuming a 10:1 dilution factor in receiving streams, a wastestream

containing 480 mg/L of ethylene glycol could be discharged to a receiving stream with a 24-hour

retention time without resulting in a DO concentration of less than 9.5 mg/L (10).

Environmental Fate and Bioaccumulation

Ethylene glycol and propylene glycol are highly soluble in water; therefore,

volatilization is not likely to be a significant pathway for removal of ethylene and propylene glycol

from water under typical natural conditions. The Henry’s Law Constants (at 25EC) for ethylene

glycol and propylene glycol are 2.3x10 atm-m /mol and 1.2-1.7x10 atm-m /mol, respectively -10 3 -8 3

(5). Propylene glycol will more readily volatilize than ethylene glycol due to its higher Henry’s

Law Constant; both are considered volatile organic compounds (VOCs) by EPA. If released to

the air, both glycols are likely to remain in the vapor phase and are expected to undergo rapid

photochemical oxidation via reaction with hydroxyl radicals (5). Several studies confirm that

neither ethylene glycol nor propylene glycol significantly volatilize to the air. In a study
Section 10.0 - Environmental Impacts

10-6

performed by a propylene glycol manufacturer, a negligible amount of propylene glycol volatilized

from a biological treatment reactor, even under favorable conditions (3). 

Because both glycols are very soluble in water, biodegradation is the most

important process that breaks down ethylene glycol and propylene glycol. Both glycols have a low

octanol/water partition coefficient (KOW), which suggests that bioaccumulation is not likely to

occur (5). Ethylene glycol and propylene glycol break down very quickly in humans and animals.

Studies have found that ethylene glycol was no longer present in body tissues just 48 hours after

exposure (5). Crayfish exposed to high concentrations of ethylene glycol (50 to 1,000 mg/L)

over a 2-month period did not bioaccumulate significant amounts of ethylene glycol (11). (See

Section 9.1 for information on the toxicity of ethylene glycol and propylene glycol.)

10.1.2 Formulated Aircraft Deicing/Anti-icing Fluids

As discussed in Section 10.1.1, both pure ethylene glycol and propylene glycol

exert a high oxygen demand on receiving streams, which may significantly affect dissolved oxygen

concentrations in these streams. ADFs will exert a lower oxygen demand than pure glycol,

primarily because ADFs are diluted with water. Because the additive package is only a small

portion of ADFs (typically less than 2%), the chemical additives should not cause a significant

increase in the oxygen demand of ADFs. However, some additives may be toxic to the

microorganisms that biodegrade them, inhibiting the biodegradation of ADFs, and therefore

reducing the BOD measured during laboratory analyses. 

Like pure ethylene glycol and propylene glycol, the glycol portion of ADFs is not

expected to bioaccumulate and will rapidly biodegrade. Propylene glycol-based ADFs would be

expected to biodegrade slightly faster than ethylene glycol-based ADFs, because pure propylene

glycol degrades faster than pure ethylene glycol. 

A summary of BOD5 and COD results for Type I, II, and IV ADFs is shown

below. The results indicate that ADFs are readily and rapidly biodegraded. Note that the Type I
Section 10.0 - Environmental Impacts

10-7

data presented are for concentrated fluid and not as applied fluid. EPA recognizes that the

propylene glycol-based Type I fluid has a lower BOD5 than the ethylene glycol-based Type I fluid

which conflicts with BOD data presented in Section 10.1.1. This occurrence may be due to the

different volume of glycol used in each formulation or varying testing conditions. In general,

Type II and Type IV solutions should have a higher BOD concentration than Type I solutions (as

applied) because they contain a higher concentration of glycol. Note that the source for the

propylene glycol and ethylene glycol fluid tests are different; data are provided by their

corresponding fluid manufacturers. Because the sources are different, test conditions (e.g.,

temperature, fluid concentration) may have varied, which could yield incomparable results.

Although the ultimate BOD values for ADFs are less than that of their corresponding pure glycol,

formulated fluids may still pose an oxygen depletion threat on receiving streams.

Fluid Type (mg/L) (mg/L) (mg/L) (mg/L) (mg/L)

COD BOD, Day 5 BOD, Day 10 BOD, Day 15 BOD, Day 20

Type I - EG based 1,260,000 873,000 1,070,000 NA 1,210,000

(concentrate)

Type I - PG based 1,400,000 840,000 NA NA NA

(concentrate)

Type II - PG based NA 730,000 NA NA NA

Type IV - EG 945,000 463,000 576,000 775,000 935,000

based

Type IV - PG based 794,000 520,000 NA NA 785,000

Source: References (12, 13, 14, 15, 16).

NA - Not available.

EG - Ethylene glycol.

PG - Propylene glycol.

COD - Chemical oxygen demand.

Although present in small amounts, fluid additives may impact the biodegradability

of ADFs. Limited data are available to assess the impact of ADF additives on the fate of ADFs;

however, tolyltriazole (TTZ) can significantly impact the degradability of ADFs. Cornell et al.

performed tests on the degradation rate of formulated fluids to assess the effects of the additive

pack without TTZ (e.g., surfactants, buffers) and where TTZ was the only additive. It was found

that TTZ has a significant impact on the degradation rate. With TTZ present at concentrations
Section 10.0 - Environmental Impacts

10-8

that might be found in airport soils, the pseudo-first order biodegradation rate constant for a

propylene glycol-based ADF (containing TTZ) was approximately three times smaller than that of

pure propylene glycol. The degradation rate also decreased as the TTZ concentration increased. 

While the additives package (without TTZ) reduced the degradation constant, the presence of

TTZ (with and without the additives package) caused a much greater decrease in the degradation

rate (17, 18). 

TTZ is composed of two isomers, 4-methyl-benzotriazole (4-MEBT) and 5-

methyl-benzotriazole (5-MEBT). U.S. Patent 5,503,775 claims that under aerobic conditions, 5-

MEBT is biodegradable while 4-MEBT is recalcitrant (17). While current work is being

performed to study the effects of TTZ on the biodegradation of ADFs and glycol, EPA believes

that no current research is being performed to study the effects of each isomer on biodegradation

rates. 

Another main concern of ADF additives is their decomposition products. The

degradation of several potential fluid additives may result in more toxic compounds than the

primary compounds. For example, TTZ is an azo compound. Azo compounds are known to

biotransform under anaerobic conditions into more toxic compounds such as aromatic amines and

nitro compounds (12). As mentioned above, TTZ may not be very degradable and may

bioaccumulate (17). Anaerobic conditions, caused by the high oxygen demand during glycol

degradation, may catalyze the formation of more toxic byproducts when additives decompose

(12). Environmental fate and bioaccumulation data are currently not available for other ADF

additives.

Inhibition testing may be used to measure a compound’s toxic potential on

biological systems (e.g., biological wastewater treatment systems). An ethylene glycol ADF

manufacturer performed bacteria inhibition testing using Type IV fluid and found the following

results.
Section 10.0 - Environmental Impacts

10-9

Fluid Type IC (mg/L) NOEC (mg/L) 50

Type I - EG based 64,000 (or 6.4% concentration) NA

Type IV - EG based 9,100 (or 0.91% concentration) 2,500 (or 0.25% concentration)

Source: Reference (13).

NOEC - No-observed-effect concentration.

IC - Concentration that inhibits growth in 50% of the test organisms. 50

NA - Not available.

These results show that ethylene glycol-based Type IV ADFs are significantly more toxic to

bacteria than Type I fluids. However, Type IV ADFs are not likely to reach POTWs in large

concentrations because these fluids are typically carried out beyond collection areas.

The same ADF manufacturer developed air emission rates in 1998. The rates are

based on fundamental chemical engineering calculations of mass transport across a boundary layer

(i.e., the glycol concentration in a given sample). These rates, shown below, indicate that the use

of propylene glycol-based ADFs results in higher air emissions than that of ethylene glycol-based

ADFs (2). However, it is important to note that wind and turbulence during storms would

disperse the vapor emissions to very low ambient concentrations. These results agree with results

predicted based solely on Henry’s Law Constant for pure ethylene glycol and propylene glycol

(see Section 10.1.1). 

Glycol Product Name Type (% wt.) (lb/gal) gal applied)

Fluid Content Content (lb glycol per 10,000

Glycol Glycol Emissions 

Glycol Air

Ethylene Deicing Fluid Concentrate I 92 8.52 9.37

Glycol Deicing Fluid XL 54 I 54 4.84 5.32

Deicing Fluid “50/50" I 48.4 4.3 4.73

Deicing/Anti-icing Fluid ULTRA+ IV 64 5.79 6.37

Propylene Typical Deicing Fluid “45/55" I 55 4.78 8.87

Glycol

Source: Reference (2).
Section 10.0 - Environmental Impacts

10-10

As discussed in Section 4.2.1, up to 4,000 gallons of Type I fluid may be used to

deice one aircraft during a severe storm event. Although air emissions factors are relatively low,

extensive use of deicing fluids during storm events may result in significant air emissions. Based

on the above information, propylene glycol-based ADFs are estimated to result in more than twice

the air emissions than ethylene glycol-based ADFs. In addition, the results show that the higher

the glycol concentration, the more air emissions are expected to occur. Therefore, it would be

expected that Type II and IV fluids would result in greater air emissions than Type I fluids. 

However, it is important to note that, while Type II and IV fluids would cause higher air emission

rates, these fluids are typically applied in much smaller volumes than Type I fluids and are

designed to stick to aircraft, which may ultimately reduce net air emissions.

10.1.3 Alternative Freezing-Point Depressants

As discussed in Section 9.3, diethylene glycol and isopropanol are both other

freezing-point depressants, although neither is currently used in for deicing/anti-icing aircraft in

the U.S. However, diethylene glycol is believed to be used currently in Europe. 

Diethylene Glycol

Diethylene glycol, though not used as the main freezing-point depressant in U.S.

ADFs, may be found in ethylene glycol-based formulations as a byproduct of the ethylene glycol

manufacturing process. Diethylene glycol is biodegradable, though not as easily as ethylene

glycol or propylene glycol, is not likely to volatilize to the air, and is not likely to bioaccumulate

(based on its low octanol water coefficient) (3, 18, 19). It has an aerobic half life of 3.5 to greater

than 20 days, depending on temperature (6). In addition to temperature, degradation rates may

also be affected by acclimation. For example, in one study, acclimated bacteria completely

degraded a sample of diethylene glycol in 5 days, while unacclimated bacteria degraded only 21%

of a diethylene glycol sample (18). Unlike ethylene glycol and propylene glycol, hydrolysis may

be an important fate process for diethylene glycol in water because it is easily hydrolyzed. 
Section 10.0 - Environmental Impacts

10-11

However, like ethylene glycol, there is potential for more toxic compounds to be formed from

anaerobic diethylene glycol degradation (e.g., acetaldehyde, ethanol, and acetate) (6).

Diethylene glycol has a theoretical oxygen demand of 1.51 grams of oxygen per

gram of diethylene glycol (18). This theoretical oxygen demand is greater than that for ethylene

glycol but less than that for propylene glycol. Several sources have studied the BOD of 5

diethylene glycol, with results ranging from 1.3% to 10% of the theoretical oxygen demand (18). 

These results are significantly lower than those for ethylene glycol and propylene glycol,

indicating that it takes a greater amount of time to completely degrade diethylene glycol.

One propylene glycol manufacturer has conducted studies comparing the 

biodegradability of diethylene glycol, ethylene glycol, and propylene glycol. BOD5 data collected

during the study were inconsistent and erratic for diethylene glycol, indicating that diethylene

glycol is not as readily biodegradable as ethylene glycol and propylene glycol (3). The COD:BOD

ratio for diethylene glycol is an order of magnitude higher than that of the other glycols, also

indicating that it is not as degradable. The lower biodegradability of diethylene glycol is most

likely due to the ether structure of the compound. The data also show that diethylene glycol takes

a longer amount of time to biodegrade than ethylene glycol and propylene glycol. A main concern

of diethylene glycol degradation is the potential for significant oxygen depletion in receiving

streams. Although diethylene glycol requires a similar amount of oxygen to degrade as other

glycols, the fact that it takes longer to degrade means that it places a strain, although lesser, on

oxygen levels in receiving streams for a longer period of time. 

Table 10-2 summarizes diethylene glycol degradation data for four different test

conditions. These data show that diethylene glycol is more easily degraded at lower

concentrations, in buffered solutions, and at higher temperatures. The removal rates and percent

removals for ethylene glycol and propylene glycol are significantly higher than those for diethylene

glycol given the same input parameters (3). 
Section 10.0 - Environmental Impacts

10-12

In summary, diethylene glycol may be a viable substitute for ethylene glycol and

propylene glycol; however, it does not offer any environmental benefits over the glycols currently

in use in the U.S. Aquatic and mammalian toxicity values are similar to those of ethylene glycol. 

Diethylene glycol requires approximately the same amount of oxygen to degrade as ethylene

glycol and propylene glycol, but it degrades more slowly. This results in a smaller daily oxygen

demand over a longer period of time. This characteristic does not strain oxygen levels as much as

the other glycols because the oxygen demand is more gradual; however, diethylene glycol is

present in a receiving stream for a longer period of time, which may potentially result in other

toxicological effects if present in high concentrations. 

Isopropanol

Isopropanol is biodegradable in water, with a half-life of between 2 and 20 days

(20). Based on its Henry’s Law Constant, it is slightly volatile (21). Upon discharge to water,

approximately 77.5% of isopropanol will stay in the water while the remainder volatilizes to the

air (20). It is highly soluble in water and is not likely to bioaccumulate; the isopropanol

concentration found in fish tissues is expected to be the same as the average isopropanol

concentration in the water from which the fish was sampled (20). When released into soil, it is

expected to biodegrade, evaporate, or seep into groundwater (22).

Isopropanol has a theoretical oxygen demand of 2.40 grams of oxygen per gram of

isopropanol (18). This theoretical oxygen demand is significantly higher than that of glycols. 

Several sources have studied the BOD (at 20EC) of isopropanol, with results ranging from 60 - 5

70% of the theoretical oxygen demand for acclimated sludge, indicating that isopropanol is highly

biodegradable (18). In addition, based on Monod-type kinetics, the maximum rate of substrate

utilization per unit mass of biomass (kmax) is very high (4.89E-06) for isopropanol (23). A high

kmax value also indicates that the pollutant is highly biodegradable. These results show rapid

biodegradation of isopropanol which, combined with a high theoretical oxygen demand, can

greatly reduce oxygen levels in receiving streams and would result in greater oxygen depletion

than either ethylene glycol or propylene glycol.
Section 10.0 - Environmental Impacts

10-13

10.1.4 Pavement Deicers

There are several pavement deicers that are available and in use by airports. As

described in Section 9.4, these deicers have varying toxicity. Like toxicity, these agents have

vastly different degradability and environmental fate characteristics. 

Urea

Excessive urea in receiving streams often accelerates algal blooms in warmer

months, due to the additional nitrogen available. Algal blooms consume large amounts of oxygen,

resulting in even greater reduced dissolved oxygen concentrations in streams, and may cause

eutrophication in lakes. Due to urea’s low octanol/water partition coefficient (-1.52 at 20 to

25EC), urea is not likely to bioaccumulate. It is also not likely to volatilize to the air because of

its low Henry’s Law Constant. It readily leaches from soil into surface and groundwater (24). 

Another factor to consider is the effect of temperature on the degradation of urea

to ammonia. Studies have shown that urea completely degrades to ammonia in 4 to 6 days in

water at 20EC and negligible degradation occurs at temperatures of less than 8EC (likely

temperatures of water bodies during deicing events) (25). Therefore, while the use of urea may

cause potential toxic effects to the aquatic environment because of ammonia formation, it may not

be as large a concern during winter months as it would during spring or summer months. 

Urea/Ethylene Glycol Mix

In a biodegradability test performed using a formulated urea and ethylene glycol

fluid, the COD was reported as 1.45 pounds of oxygen per pound of fluid and the BOD as 0.94

pounds of oxygen per pound of fluid. The percent of fluid biodegraded after 21 days (at 20EC)

was reported as 94% (26). 
Section 10.0 - Environmental Impacts

10-14

Potassium Acetate

All forms of potassium acetate are readily biodegradable. It exerts a BOD that is

much lower than other runway deicers (e.g., urea). Reported BOD values are in the range of 5

0.14 to 0.30 grams of oxygen per gram of potassium acetate (12). 

Calcium Magnesium Acetate (CMA)

CMA is also readily biodegradable, which makes it a favorable alternative runway

anti-icer (26). EPA was not able to locate any information regarding BOD values for CMA. 5

Sodium Acetate

Sodium acetate is readily biodegradable even at low temperatures. One

manufacturer’s sodium acetate-based deicer has a BOD of 0.58 grams of oxygen per gram of 5

anhydrous sodium acetate at 20EC. The chemical oxygen demand is 0.78 grams of oxygen per

gram of anhydrous sodium acetate (26). 

Sodium Formate

Sodium formate is also highly biodegradable; one specific sodium formate-based

deicer has a BOD5 of 0.23 grams of oxygen per gram of sodium formate, but this rate is highly

dependent on temperature (26). 

Alternative Pavement Deicers

Transport Canada and ADI Nolan Davis, Inc. conducted a three-year evaluation to

compare the performance and impacts of urea and glycols in storm water runoff to that of the

newer pavement deicing agents (e.g., sodium formate, potassium acetate, CMA) (12). The results
Section 10.0 - Environmental Impacts

10-15

show that the newer chemicals are “relatively benign” compared to urea and glycols, and are

summarized as follows:

C Sodium formate - had little or no impact on water chemistry. It also was

difficult to detect, which indicates rapid degradation. Sodium was more

frequently detected than formate, although it was difficult to solely

attribute detected sodium concentrations to the application of sodium

formate. The fact that formate was difficult to detect indicates that it is not

persistent in the environment.

C CMA - had little or no impact on water chemistry, and calcium,

magnesium, and acetate were all readily detected.

C Potassium acetate - had little impact on surface water, except that BOD5

levels significantly increased, which was attributed to increased acetate

levels. Potassium acetate was more easily detected than sodium formate

and had no discernable impact on groundwater, vegetation, and other soil

and stream life.

Sand

Sand, while not degradable, can clog storm drains and contaminate water bodies

through increased erosion and sediment buildup. 

Salts

Salts are not applied to airside pavements, but runoff from roadside pavements can

cause water quality in receiving streams to deteriorate. 

10.2 Reports of Environmental Impacts from Airport Deicing Operations

The deicing or anti-icing of aircraft and runways is a necessary operation at many

airports during the winter months. The release of deicing/anti-icing agents can negatively impact

the environment or local POTWs that receive discharges from airports. As part of this study,
Section 10.0 - Environmental Impacts

10-16

EPA reviewed published literature for evidence of environmental impacts on aquatic life, human

health, POTW operations, and the quality of receiving waters due to the discharge of deicing antiicing chemicals. 

Literature abstracts were obtained through the computerized information system,

DIALOG (Knight-Ridder Information, February 1999), which provides access to scientific journal

abstracts such as Pollution Abstracts, Aquatic Science and Fish Abstracts, and Water Resource

Abstracts. Newspaper articles were also obtained through DIALOG from 25 randomly selected

newspapers serving major northern metropolitan areas. EPA acknowledges that the information

in these newspaper articles may not be scientifically accurate or technically representative of

actual environmental impacts; however, EPA believed it was important to recognize additional

sources of information regarding potential environmental impacts. 

In the review of literature abstracts and newspaper articles, environmental impacts

were noted from 17 airports and in six general studies. Impacts included: (1) aquatic life effects

such as fish kills, growth of biological slimes, elimination of aquatic life, stressed invertebrate

communities, and impaired fisheries; (2) effects on wildlife, birds and cattle; (3) human health

problems (worker and population exposure - headaches, nausea); (4) aesthetic effects (odor,

color, foaming); and (5) effects on the quality of receiving waters (low DO, high BOD, organic

enrichment), groundwater, water supplies, and soils. Impacts were mainly due to presence of

ethylene and propylene glycol in the receiving streams from storm water runoff. New concerns

with the aquatic toxicity of ADF additives were also noted, as well as concerns with the release of

other toxic organic chemicals, oil and grease, and metals from airport operations. Table 10-3

summarizes the information collected from the literature.

Specifically, past and current environmental impacts due to the direct discharge of

ADF included: (1) aquatic life effects, such as fish kills (four airports), elimination of all aquatic

life (two airports), bacterial growth (one airport), concerns with shrimp farming (one airport); (2)

aesthetic effects, such as odors and foaming (four airports); (3) effects on the quality of receiving
Section 10.0 - Environmental Impacts

10-17

waters, such as exceeding water quality standards (three airports); and (4) effects on water

supplies (1 airport). 

It is important to note that many of the airports discussed have made

improvements in the collection and treatment of deicing fluids over the past 5 years. Contained

deicing areas, increased recycling, and newly built storm water retention basins are all examples of

recent improvements. Consequently, the information presented in Table 10-3 may not represent

current airport deicing operations.

10.3 Effect on POTWs

Pretreatment standards are designed to prevent the discharge of pollutants that

pass through, interfere with, or are otherwise incompatible with the operation of POTWs. 

Section 307(b) of the Clean Water Act authorizes EPA to establish pretreatment standards for

pollutants that pass through POTWs or interfere with treatment processes or sludge disposal

methods at POTWs. To assess pass-through, EPA generally compares the POTW secondary

treatment performance for each pollutant under consideration for regulation to the treatment

performance achieved by direct dischargers using best available technologies economically

achievable (BAT). This ensures that 1) the wastewater treatment performance for indirect

dischargers is equivalent to that for direct dischargers, and 2) the treatment capability and

performance of the POTW are considered when regulating the discharge of pollutants from

indirect dischargers. Because, at this time, EPA is conducting a study rather than developing

effluent limitations for airport deicing operations, a formal POTW pass-through analysis was not

performed. However, EPA collected information from POTWs to better understand the impacts

wastewater containing deicing/anti-icing chemicals have on POTWs. Appendix A contains

information regarding the location of airports referenced in this section.
Section 10.0 - Environmental Impacts

10-18

10.3.1 EPA POTW Questionnaires

As discussed in Section 3.2.3, EPA mailed questionnaires to nine POTWs that

accept or have accepted wastewater discharges containing deicing/anti-icing chemicals. EPA

received responses to eight of the nine POTW questionnaires. The information collected from

these questionnaires, in addition to information collected during site visits, from literature and

newspaper searches, and from discussions with airport, airline, and POTW trade association

members, was used to assess whether wastewater discharges from airport deicing operations pass

through or interfere with POTW operations. Responses to the POTW questionnaires are

discussed in the following subsections.

10.3.1.1 Chemicals Typically Found in Discharges

All POTWs surveyed indicated accepting wastewater containing ethylene glycol,

propylene glycol, or both. Other chemicals reported in wastewater discharges accepted by the

POTWs include potassium acetate, sodium formate, potassium formate, and urea, which are all

used as pavement deicers. The Patapsco Wastewater Treatment Plant, which receives discharges

from the Baltimore/Washington International Airport, indicated that they accept discharges

containing diethylene glycol in addition to ethylene glycol and propylene glycol. See Sections 9.3

and 10.1.3 for more information regarding diethylene glycol.

10.3.1.2 Contribution of Wastewater Containing Deicing/Anti-Icing Chemicals to

POTWs

Based on information from the questionnaires, discharges of wastewater

containing deicing/anti-icing chemicals do not significantly contribute flow and organic loading to

POTW operations. The daily average hydraulic loading for the questionnaire recipients ranges

from 1 to 250 million gallons. The percentage of flow from accepted airports relative to total

POTW flow ranges from less than 0.01% to 3%, with a mean contribution of approximately one

percent. The percentage of BOD accepted from airports relative to total POTW BOD loading
Section 10.0 - Environmental Impacts

10-19

ranges from 0% to 41%, with a mean contribution of approximately four percent. Therefore,

airports discharging wastewater containing deicing/anti-icing chemicals to POTWs contribute

relatively more BOD loading than hydraulic loading.

10.3.1.3 Documented Negative Impacts at POTWs

Several POTWs reported increased secondary sludge generation and operating

costs after accepting wastewater containing aircraft and airfield pavement deicing/anti-icing

chemicals. Additional sludge is generated as a result of accepting high loads of glycol and other

organic materials that are easily digested by biological treatment microorganisms. Based on

biological treatment operating principles, if a plant were to receive a sudden load of highly

concentrated organic matter, then more waste sludge would be generated. The extra sludge

would need to be wasted (i.e., disposed of) in order for the POTW to meet its discharge

limitations. Most POTWs have sludge dewatering on site to handle current sludge generation and

any excess sludge. However, additional sludge dewatering incurs energy, chemical, and labor

costs, in addition to disposal costs. The addition of glycols and other organic matter in POTW

influents may also require additional aeration and microorganisms to degrade these pollutants. 

The Wyandotte Wastewater Treatment Plant, to which the Detroit Metropolitan Airport

discharges its wastewater, has experienced significant oxygen depletion in its secondary biological

treatment system as a result of accepting wastewater containing glycols from deicing/anti-icing

operations. When this occurs, the POTW either increases the oxygen supplied to the treatment

system or asks the airport to reduce its discharge flow. Additional aeration also incurs increased

operation and maintenance costs due to associated additional energy and labor.

Although all POTW questionnaire recipients currently accept wastewater from

airport deicing/anti-icing operations, two POTWs indicated that they have previously rejected

wastewater containing airport deicing/anti-icing chemicals. The Moon Township Municipal

Authority, which accepts wastewater from the Pittsburgh International Airport, was forced to

reject discharges in 1993. Problems began shortly after the airport first began discharging

wastewater containing deicing/anti-icing chemicals. The POTW experienced a drop in dissolved
Section 10.0 - Environmental Impacts

10-20

oxygen concentrations and a problem with maintaining residual chlorine. The POTW solved these

initial problems after working with the airport’s contractor to adjust discharge pollutant loads and

flow rates. However, even after an agreement was reached, the POTW received several large

accidental discharges of wastewater containing deicing/anti-icing chemicals; the most recent

accidental discharge caused the plant to completely lose all dissolved oxygen and killed all of the

biomass in the treatment system. After this incident, the POTW refused to accept further

discharges from the airport. The airport responded by hiring a different contractor to manage

discharges of wastewater from deicing/anti-icing operations, and the POTW now accepts the

airport’s discharges.

The Trinity River Authority Central Regional Wastewater System, which accepts

wastewater containing deicing/anti-icing chemicals from the Dallas/Ft. Worth International

Airport, experienced a similar situation to that described in Pittsburgh. The POTW received a

discharge containing an excessively high glycol concentration, which upset the treatment plant. 

The POTW then refused to accept discharges until the airport installed holding ponds to control

discharges to the POTW. Even with controlled discharge, the POTW must maintain a higher

concentration of microorganisms in its treatment system during the winter to better accommodate

wastewater discharges containing deicing/anti-icing chemicals. 

The Salt Lake City Water Reclamation POTW also experienced a treatment plant

upset resulting from the acceptance of airport deicing/anti-icing wastewater from the Salt Lake

City International Airport. In this case, the POTW did not require that the airport stop

discharging. The problem was solved when the POTW required the airport to control its rate of

discharge. 

The Columbia Boulevard Wastewater Treatment Plant, which accepts wastewater

from the Portland International Airport, requests that the airport avoid discharging during periods

of high hydraulic loading. The POTW is forced to bypass its secondary treatment when the

hydraulic capacity of the system is exceeded. The POTW’s secondary treatment is where

treatment of deicing/anti-icing chemicals typically occurs.
Section 10.0 - Environmental Impacts

10-21

Although no documentation was provided, POTWs are also concerned with

potential byproducts from the degradation of deicing/anti-icing chemicals (e.g., acetaldehyde). 

POTWs expressed concern over the fact that byproducts may potentially interfere with or pass

through a POTW.

10.3.1.4 Documented Positive Impacts

One POTW has benefitted from accepting wastewater containing deicing/anti-icing

chemicals. After implementing a batch discharge system, the Kansas City Todd Creek

Wastewater Treatment Plant has experienced a reduction in its final effluent BOD by an average

of 3 to 4 mg/L. 

10.3.2 Evidence of POTW Pass-Through

Although EPA did not perform a thorough POTW pass-through analysis for this

study, EPA compared the ethylene glycol and propylene glycol percent removal achieved by a

POTW with that achieved by direct dischargers that have implemented collection and on-site

treatment technologies. EPA was not able to find a published source that provides a POTW

percent removal (based on activated sludge or an equivalent technology) for ethylene glycol or

propylene glycol. However, the Moon Township POTW performed sampling in 1993 to study

the effectiveness of ethylene glycol treatment and submitted these data to EPA. The sampling

data are summarized below.
Section 10.0 - Environmental Impacts

10-22

Date (mg/L) (mg/L) Percent Removal

Influent Ethylene Effluent Ethylene

Glycol Concentration Glycol Concentration

4/12/93 36 13 64

4/13/93 20 11 45

4/14/93 2.7 3.5 NR

4/15/93 14 7.9 44

4/20/93 16 4.1 74

NR - Not removed.

Data based on a discharge of 1,500 lbs/day of ethylene glycol from the airport.

The data show that the POTW generally experienced low influent concentrations of ethylene

glycol and that the average effluent concentration was approximately 10 mg/L. The POTW was

generally able to treat the influent ethylene glycol when the influent concentration was already

very low. The average POTW percent removal in the data provided was 57%, as compared to

>99% at an EPA sampled airport with on-site biological treatment. 

As shown in Section 13.2, most airports with indirect discharge permits have limits

or monitoring requirements for glycols and/or BOD. Based on responses to the POTW

questionnaire, several POTWs reported that they are able to accommodate wastewater containing

deicing/anti-icing chemicals, but these discharges must be monitored with controlled discharge

into the sewer system, including a period of acclimation at the beginning of each deicing season. 

As more airports begin discharging their wastewater containing deicing/anti-icing chemicals, more

POTWs will need to control the amount of glycols or BOD that are discharged on a daily basis. 

These limits will be based on the design requirements and effluent limits achievable at the POTW. 

Although few adverse effects have resulted from controlled wastewater discharges, POTWs

remained concerned about accidental discharges and the potential for deicing/anti-icing chemical

byproducts to upset the treatment plant. Additional monitoring is needed to better understand the

overall impacts that wastewater from deicing/anti-icing operations have on POTW operations.
Section 10.0 - Environmental Impacts

10-23

10.4 References

1. University of Massachusetts. Workshop: Best Management Practices for Airport

Deicing. July 1999 (DCN T10661).

2. McCready, D., PhD., P.E. Estimation of Glycol Air Emissions from Aircraft

Deicing. January 1998 (DCN T10481).

3. Arco Chemical Company. Summary Report for Glycol Biodegradability Testing

Program. April 1990 (DCN T10383).

4. U.S. Environmental Protection Agency. Emerging Technology Report: Preliminary

Status of Airplane Deicing Fluid Recovery Systems. September 1995 (DCN

T04674).

5. U.S. Department of Health and Human Services. Toxicological Profile for

Ethylene Glycol and Propylene Glycol. September 1997 (DCN T11084). 

6. Environment Canada. Canada Water Quality Guidelines for the Protection of

Aquatic Life (DCN T10378).

7. U.S. Environmental Protection Agency. Meeting Summary Union Carbide

Corporation. May 1998 (DCN T10298).

8. Sills, R.D., and P.A. Blakeslee. Environmental Impact of Deicers in Airport

Stormwater Runoff. 1992.

9. Arco Chemical Company. Ultimate Biochemical Oxygen Demand Test. February

1996 (DCN T10384).

10. Environment Canada. Scientific Considerations in the Development of a Revised

CEPA Glycol Guideline Value. November 1996 (DCN T10376).

11. Abdelghani, A.A., A.C. Andersion, G.A. Khoury, and S.N. Chang. Fate of

Ethylene Glycol in the Environment. 1990.

12. Air Combat Command. Literature and Technology Review Report for Aircraft and

Airfield Deicing. September 1997.

13. Letter from Nancy Diebler Wesselman, Union Carbide Corporation to David

Hoadley, U.S. EPA. May 6, 1999 (DCN T10548).
Section 10.0 - Environmental Impacts

10-24

14. Letter from Stephen Kramer, Octagon Process Inc. to Shari Zuskin, U.S. EPA. 

April 26, 1999 (DCN T10543).

15. Lyondell Chemical Company. ARCO Plus® Propylene Glycol Aircraft Deicer

Qualification Data Summary (DCN T11097).

16. Calculation Sheets for COD and BOD Concentrations for an Ethylene GlycolBased Type I Formulation (DCN T11098).

17. Cornell, J.S., D.A. Pillard, M.T. Hernandez. Chemical Components of Aircraft

Deicer Fluid: How They Affect Propylene Glycol Degradation Rates and Deicing

Waste Stream Toxicity. 1998 (DCN T10484). 

18. Verschueren, K. Handbook of Environmental Data on Organic Chemicals., Third

Edition. 1996. 

19. NTP Chemical Repository for Diethylene Glycol (DCN T10571).

20. U.S. Environmental Protection Agency. Toxic Release Inventory Fact Sheet for

Isopropanol. (DCN T10573).

21. U.S. Environmental Protection Agency. Draft Cleaner Technologies Substitutes

Assessment (CTSA): Screen Reclamation. EPA 744R-94-005a. September 1994.

22. Material Safety Data Sheet for Isopropanol (DCN T10574).

23. U.S. Environmental Protection Agency. Technical Support Document for the

Final Effluent Limitations Guidelines and Standards for the Pharmaceutical

Manufacturing Point Source Category. EPA-821-B-98-005, Washington, D.C.,

1998.

24. U.S. Environmental Protection Agency. International Screening Information Data

Sets (SIDS). 1997.

25. Aldrich Catalog Handbook of Fine Chemicals. 1996-1997.

26. Material Safety Data Sheets and Product Specifications for Runway Deicers (DCN

T10586).
Section 10.0 - Environmental Impacts

10-25

Table 10-1

Ultimate BOD Values for Pure Ethylene Glycol and

Propylene Glycol Acclimated Sludge Seeds

Day BOD Value (in mg O /L) BOD Value (in mg O /L)

Ethylene Glycol Propylene Glycol

2 2

4EC - 1.3 or 3.3 mg/L test substance

0 0 0

5 150,000 75,000

10 150,000 150,000

17 300,000 225,000

27 525,000 375,000

35 825,000 675,000

4EC - 6.7 or 10.0 mg/L test substance

0 0 0

5 30,000 0

10 45,000 60,000

17 90,000 120,000

27 165,000 510,000

35 495,000 900,000

4EC - 20.0 mg/L test substance

0 0 0

5 10,000 0

10 20,000 15,000

17 30,000 40,000

27 65,000 Discarded

10EC - 1.3 or 3.3 mg/L test substance

0 0 0

5 -75,000 -75,000

10 300,000 675,000

16 600,000 1,050,000

20 825,000 1,200,000

27 1,350,000 1,575,000

35 1,800,000 2,100,000
Table 10-1 (Continued)

Section 10.0 - Environmental Impacts

Day BOD Value (in mg O /L) BOD Value (in mg O /L)

Ethylene Glycol Propylene Glycol

2 2

10-26

10EC - 6.7 or 10.0 mg/L test substance

0 0 0

5 0 30,000

10 105,000 615,000

16 360,000 960,000

20 870,000 1,005,000

27 1,005,000 1,140,000

35 1,155,000 1,290,000

10EC - 20.0 mg/L test substance

0 0 0

5 0 35,000

10 40,000 Discarded

16 350,000 Not Tested

Source: Reference (11).
Section 10.0 - Environmental Impacts

10-27

Table 10-2

Biological Degradation Results for Diethylene Glycol

Parameter

Run

1 2 3 4

Diethylene glycol 2,100 1,700 1,000 160

concentration (mg/L)

Biomass acclimated acclimated acclimated acclimated

Temp. EC 19.3 9.8 19.2 19.4

pH unbuffered unbuffered buffered unbuffered

Detention time (hours) 27 60 48 33

Initial COD 3,100 5,600 3,200 250

concentration (mg/L)

Effluent COD 2,300 3,900 1,040 30

concentration (mg/L)

Removal rate (1/day) 0.31 0.17 1.1 5.3

Percent removal 25.8 30.4 67.5 88

Source: Reference (3).
10-28

Section 10.0 - Environmental Impacts

(a) EPA recognizes that not all impacts presented in this table are scientifically based and the Agency takes no position on the accuracy of any conclusion derived from

the cited materials. Due to recent improvements in the collection and treatment of deicing fluids at airports, the information presented in this table may not represent

current airport deicing conditions.

Table 10-3

Reported Environmental Impacts from Airport Deicing Operations

Airport Site/Study Environment Biota/Effect Impacts (a)

Exposure

Seattle-Tacoma Miller Creek, Des Ethylene glycol in receiving Toxic effects on fish 1993 - Tacoma News Tribune reports “death”

International Moines Creek, Puget streams due to runoff of Miller Creek due to runoff from airport. 

Seattle, WA Sound Salmon no longer present in creek. Airport to

(SEA) conduct water-quality study.

1995 - Seattle Post-Intelligencer reports

environmental group filed lawsuit against

airport charging regularly fouling nearby

salmon-bearing streams in violation of water

pollution laws and permit. Excessive amounts

of oil, grease, metals, toxic petrochemicals and

ethylene glycol entering Des Moines Creek,

Miller Creek and eventually Puget Sound.

Westchester Kensico Reservoir Propylene glycol in reservoir Population exposure 1999 - New York Times reports propylene

County glycol found in Kensico Reservoir at levels high

White Plains, NY enough to set off warning system. Reservoir

(HPN) serves New York City and most of southern

Westchester.

Rye Lake, Blind Deicers in receiving streams --- 1997 - Journal article summarizes program to

Brook; Blind Brook due to runoff and in discharges improve storm water management at airport

WWTP to WWTP including construction of detention ponds to

lessen impact on receiving waters, separation of

deicing runoff, and discharging limited amount

of deicing runoff to local WWTP. Concern

with protecting NYC water supply and impact

of BOD loading on WWTP.
10-29

Section 10.0 - Environmental Impacts

Table 10-3 (Continued)

Airport Site/Study Environment Biota/Effect Impacts (a)

Exposure

(a) EPA recognizes that not all impacts presented in this table are scientifically based and the Agency takes no position on the accuracy of any conclusion derived from

the cited materials. Due to recent improvements in the collection and treatment of deicing fluids at airports, the information presented in this table may not represent

current airport deicing conditions.

General Environmental Deicers in receiving streams Toxic effects on aquatic life - 1990 - Michigan DNR conducted investigation

Impact of Deicers in and groundwater due to runoff fish kills into aircraft and runway deicing. Concerns

Airport Stormwater with aquatic toxicity of ammonia, oxygen

Runoff depletion, organic enrichment of receiving

streams and obnoxious odors during

biodegradation process. Article notes fish kills

from Lambert Field discharge and impairment

to aquatic communities at Pittsburgh,

Nashville, and Anchorage. Groundwater

contamination at Michigan airports may be

occurring. Regulatory action necessary to

control indiscriminate releases.

Lambert-St. Louis Coldwater Creek Ethylene glycol in receiving Population exposure 1995 - St. Louis Post Dispatch reports

International stream due to runoff thousands of gallons of ethylene glycol entering

St. Louis, MO Coldwater Creek. Residents along creek report

(STL) foul odors. Airport ordered by EPA and State

Department of Natural Resources to make

improvements. Airport says cannot meet

ordered deadline and faces fines of up to

$10,000/day.

Cleveland Rocky River Toxic chemicals in receiving --- 1991 - Columbus Dispatch reports state is in

International stream litigation with airport over flow of chemicals

Airport into Rocky River. Chemicals detected more

Cleveland, OH than decade ago, but no fish kills attributed.

(CLE)

Detroit Detroit River Ethylene glycol in receiving --- 1990 - Detroit Free Press reports state officials

Metropolitan stream investigating allegations of airport runoff

Romulus, MI polluting Detroit River. Ethylene glycol

(DTW) flowing untreated from ponds into storm drains.
10-30

Section 10.0 - Environmental Impacts

Table 10-3 (Continued)

Airport Site/Study Environment Biota/Effect Impacts (a)

Exposure

(a) EPA recognizes that not all impacts presented in this table are scientifically based and the Agency takes no position on the accuracy of any conclusion derived from

the cited materials. Due to recent improvements in the collection and treatment of deicing fluids at airports, the information presented in this table may not represent

current airport deicing conditions.

Dayton Municipal Mill Creek Ethylene glycol in receiving Fish kills; population exposure 1991 - Columbus Dispatch reports fish kill in

Airport stream and groundwater Mill Creek in 1987. 

Dayton, OH

(DAY) Associated Press reports 1998 - Ohio EPA

cites at least seven times since 1978 spills have

affected the quality of receiving streams. In

1996, airport paid $2.6 million to settle lawsuit

by homeowners for contaminated well water.

Chicago O’Hare NRDC Lawsuit Ethylene glycol releases --- 1998 - Chicago Tribune reports NRDC

International contends O’Hare has violated federal reporting

Chicago, IL requirements (time, place, quantity)

(ORD) approximately 180 times since Nov. 1996 in its

use of ethylene glycol. Airport reports average

use of 241,689 lbs/day. NRDC estimates

84,591 lbs/day being released to environment. 

EPA investigating allegations.

Cincinnati/ Elijah Creek Deicing chemicals in receiving Effects on aquatic life 1992 - Associated Press reports state has cited

Northern stream population exposure; aesthetic airport for discharge of deicing chemicals. 

Kentucky effects Major impact on Elijah Creek. Discharges

International harmed aquatic life, caused unpleasant odors

Erlanger, KY and discoloration of creek.

(CVG)
10-31

Section 10.0 - Environmental Impacts

Table 10-3 (Continued)

Airport Site/Study Environment Biota/Effect Impacts (a)

Exposure

(a) EPA recognizes that not all impacts presented in this table are scientifically based and the Agency takes no position on the accuracy of any conclusion derived from

the cited materials. Due to recent improvements in the collection and treatment of deicing fluids at airports, the information presented in this table may not represent

current airport deicing conditions.

Airborne Express Lytle Creek Deicers in receiving stream Effects on aquatic life - fish 1998 - Associated Press reports disappearance

(ABX Air, Inc.) kills; population exposure; of aquatic life in Lytle Creek and subsequent

Wilmington, OH effects on wildlife disappearance of birds. Foul odors reported. 

(ILN) Residents complaining of illness. Thousands of

fish killed (bass, blue gill). State EPA issued

airport a notice of violation for exceeding limit

for deicing runoff. Airport has established a

manmade wetland to breakdown deicers before

discharge.

Portland Columbia Slough Glycols in receiving water due Effects on aquatic life (glycols); 1999 - Oregonian reports a Portland Legislator

International to runoff; urea in land area severe oxygen shortages but no (Randy Leonard) is drafting legislation (the

Portland, OR fish kills. Urea increased grass Columbia Slough bill) that would order the

(PDX) growth, which attracted wildlife airport to stop discharging glycol into any body

and posed a hazard to jets. of water. (Note that the legislation did not

pass.) Columbia Slough already badly polluted

and very sluggish and cannot handle load of

glycol. Airport trying to minimize discharges,

but says ban difficult to achieve. In 1998,

Oregon DEQ began preparing permit to limit

discharge of glycol - some to Columbia Slough,

Portland sewers, Columbia River and off-site

disposal. Discharges to be corrected by year

2005. Airport stopped using the runway deicer

urea and started using potassium formate. Note

that Oregon DEQ issued an NPDES permit to

the airport to implement BMPs to reduce

deicing storm water runoff to the Columbia

Slough.
10-32

Section 10.0 - Environmental Impacts

Table 10-3 (Continued)

Airport Site/Study Environment Biota/Effect Impacts (a)

Exposure

(a) EPA recognizes that not all impacts presented in this table are scientifically based and the Agency takes no position on the accuracy of any conclusion derived from

the cited materials. Due to recent improvements in the collection and treatment of deicing fluids at airports, the information presented in this table may not represent

current airport deicing conditions.

Minneapolis-St. Minnesota River Glycols in receiving stream due Effects on aquatic life - low 1993 - Star Tribune reports state issued new

Paul International to runoff oxygen levels but no permit for airport requiring reduced discharges

Woodland, MN documented fish kills and extensive monitoring. Glycol is adding

(MSP) stress to Minnesota River and ability to recover

from other pollutants, particularly agricultural

chemicals.

Greater Buffalo Ellicott Creek Ethylene glycol and propylene --- 1994 - Buffalo News reports on concerns for

International glycol in receiving stream Ellicott Creek. Residents report seeing foaming

Cheektowaga, NY material in stream.

(BUF)

Pittsburgh McClarens Run, Propylene glycol and urea in Fish kills; population exposure 1998 - Pittsburgh Post-Gazette reports

International, Enlow Run, and receiving water Pennsylvania DEP ordered airport to correct

Pittsburgh, PA Montour Run long-standing water pollution problems caused

(PIT) by glycol deicers, as well as other groundwater

and discharge problems. Strong antifreeze odor

also noted. In 1994, airport had agreed to stop

harmful deicing practices and paid $60,268 to

state’s Clean Water Fund. In 1996, skiers, and

fishermen complained of headaches and nausea

and strong odors. PA DEP filed lawsuit

because of permit violations. Violations

include urea, glycols, phenol, xylene, ethyl

benzene, and oil/grease. Fines up to

$25,000/day for past violations. Fish kills

occurred in winter of 1992-93 and 1993-94.
10-33

Section 10.0 - Environmental Impacts

Table 10-3 (Continued)

Airport Site/Study Environment Biota/Effect Impacts (a)

Exposure

(a) EPA recognizes that not all impacts presented in this table are scientifically based and the Agency takes no position on the accuracy of any conclusion derived from

the cited materials. Due to recent improvements in the collection and treatment of deicing fluids at airports, the information presented in this table may not represent

current airport deicing conditions.

PIT (cont.) Montour Run and Deicing fluids in receiving Effects on aquatic life 1998 - Journal article presents results of 1996

Tributaries streams due to runoff study on impacts of airport runoff on water

quality and aquatic life. Principal effects

related to runway deicing operations. High

BOD due to glycols and urea. High

concentrations of ammonia. Organic load

stimulated growth of dense biological slimes on

streambeds. Invertebrate communities severely

stressed and dominated by pollution tolerant

species. Fishery of watershed impaired.

Anchorage Lake Hood Ethylene glycol in receiving Toxic effects on wildlife 1991 - Anchorage Daily News reports concerns

International stream due to runoff for wildlife that use Lake Hood. Also concerned

Airport with oil/grease and aviation fuel.

Anchorage, AK

(ANC)

Baltimore/ Sawmill Creek, Ethylene glycol in receiving Toxic effects on aquatic life; 1998 - Washington Post/Baltimore Sun report

Washington Stony Run, Cabin streams due to runoff population exposure; aesthetic lawsuit filed by NRDC against airport for

International Branch, Kitten effects violating CWA over past 3 years. Residents

Baltimore, MD Branch, Muddy complain of odor and foaming. Concern for

(BWI) Bridge Branch Chesapeake Bay. Problems with $16 million

dollar deicing collection system. Concentration

of glycol in Sawmill Creek more than 6X level

to kill aquatic life.
10-34

Section 10.0 - Environmental Impacts

Table 10-3 (Continued)

Airport Site/Study Environment Biota/Effect Impacts (a)

Exposure

(a) EPA recognizes that not all impacts presented in this table are scientifically based and the Agency takes no position on the accuracy of any conclusion derived from

the cited materials. Due to recent improvements in the collection and treatment of deicing fluids at airports, the information presented in this table may not represent

current airport deicing conditions.

BWI (cont.) Toxicity of Deicing chemicals in receiving Potential acute toxicity to 1995 - Journal article on study designed to

Stormwater streams due to runoff aquatic life investigate the acute toxicity of storm water

from BWI. Samples from winter storm events

caused acute toxicity to both fathead minnow

and daphnid with LC values as low as 1.0- 50

2.0% effluent due to glycol-based deicers. 

High oxygen demand and elevated nitrogen

levels also potential problems. Samples from

rain events during nonwinter months did not

cause acute-toxicity unless associated with fuel

spills.

Denver Third Creek, Barr Propylene glycol in receiving Effects on aquatic life - all life 1997/1998 - Denver Post/Rocky Mountain

International Lake stream killed due to low oxygen levels; News report spills of propylene glycol into

Airport population exposure; aesthetic Third Creek. All aquatic life for 2 miles in

Denver, CO effects Third Creek killed due to depletion of oxygen. 

(DIA) Concern for bird sanctuary at Lake Barr.

Farmers concerned for cattle. Complaints

about odor and color. In 1998 dam built to

protect Third Creek from runoff broke.
10-35

Section 10.0 - Environmental Impacts

Table 10-3 (Continued)

Airport Site/Study Environment Biota/Effect Impacts (a)

Exposure

(a) EPA recognizes that not all impacts presented in this table are scientifically based and the Agency takes no position on the accuracy of any conclusion derived from

the cited materials. Due to recent improvements in the collection and treatment of deicing fluids at airports, the information presented in this table may not represent

current airport deicing conditions.

General Management of Deicing chemicals in receiving Toxic effects on aquatic life; 1994 - Journal article states principal

Aircraft Deicing streams due to runoff and in POTW operations effects environmental impact of deicing activities is

Fluids discharges to WWTPs oxygen demand. CBOD of ethylene glycol 5

ranges from 400,000-800,000 mg/L and

propylene glycol > 1 x 10 mg/L (untreated 6

domestic wastewaters is 200-300 mg/L). Onehalf of deicing fluids ends up in storm water. 

Ammonia released from urea potentially toxic

to aquatic life and contributes to nitrogenous

oxygen demand. Various alternative

technologies and strategies exist depending

upon airport and are discussed in article. 

Disposal at municipal wastewater treatment

plants dependent on plant location, capacity,

and charges for treating high-BOD wastes.

General Management of Deicers in receiving streams Toxic effects on aquatic life; 1992 - Master thesis research identifies use and

Deicing Constituents and groundwater due to storm aesthetic effects management practices of deicing constituents

water discharges (glycol, urea, CMA, and sodium formate). 

Concerns of discharges include high BOD,

nitrate and nitrite enrichment of surface and

groundwaters, impaired aesthetic water quality,

ammonia formation, and overall toxicity to

aquatic life. 
10-36

Section 10.0 - Environmental Impacts

Table 10-3 (Continued)

Airport Site/Study Environment Biota/Effect Impacts (a)

Exposure

(a) EPA recognizes that not all impacts presented in this table are scientifically based and the Agency takes no position on the accuracy of any conclusion derived from

the cited materials. Due to recent improvements in the collection and treatment of deicing fluids at airports, the information presented in this table may not represent

current airport deicing conditions.

Major Detection of Aircraft Tolytriazoles present in Toxic effects on microorganisms 1998 - Journal article presents results of

International Deicing/Anti-icing subsurface water samples from research that describes first evidence that

North America Fluid Additives airport deicing activities constituents within ADFs, other than glycols,

(ADFs) in Water are present in subsurface water samples from a

Monitoring Well major North American airport at

environmentally significant concentrations. 

Tolytriazoles concentrations approximately 25

times higher than reported EC50 values in

Microtox assays. Previous glycol levels from

well were 24,410 mg/L.

General Environmental Deicing fluids in receiving --- 1995 - NRDC study of most important

Impacts of streams due to runoff environmental issues and best management

America’s Airports techniques to mitigate them. Surveyed 125

busiest airports (46 responded) and in-depth

research at government agencies on 50 busiest. 

Significant environmental impacts common at

most airports and regulatory framework

currently in place inadequate. Deicing and

water quality one of the significant impacts. 

Study recommends: (1) developing effluent

guidelines; (2) addressing worker health and

safety from ethylene glycol exposure; (3)

lowering threshold of national storm water

program to include smaller airports; (4)

conducting research on deicing alternatives; (5)

requiring airports to report releases in TRI; (6)

making storm water pollution prevention plans

public.
10-37

Section 10.0 - Environmental Impacts

Table 10-3 (Continued)

Airport Site/Study Environment Biota/Effect Impacts (a)

Exposure

(a) EPA recognizes that not all impacts presented in this table are scientifically based and the Agency takes no position on the accuracy of any conclusion derived from

the cited materials. Due to recent improvements in the collection and treatment of deicing fluids at airports, the information presented in this table may not represent

current airport deicing conditions.

General Petition to Require --- --- 1997 - NRDC, Defenders of Wildlife, National

SIC 45, Audubon Society, and Humane Society petition

Transportation by EPA to initiate rulemaking requiring airports,

Air, To Report airline terminals, and aircraft maintenance

Releases of Toxic facilities to report releases of toxic chemicals

Chemicals listed on TRI.

Basis of petition is ranking (3rd) as industry for

inclusion in TRI. 58 million pounds of ethylene

glycol released/year. Use increasing and

cheaper than alternatives. Other toxics include

trichloeothylene, methylene chloride, acetone,

chloroform, methyl ethyl ketone, isopropyl

alcohol, glycol ethers, toluene, xylene and other

petroleum distillates. Petition cites examples of

ethylene glycol toxicity to humans and wildlife,

health effects of other toxics, and significant

human and wildlife exposures from deicing

operations. Petition published in the Federal

Register and awaiting further action.

Sources: DIALOG database (Journals and Newspaper Articles) - February, 1999 Retrieval, Internet and States.
Section 11.0 - Pollutant Loadings and Costs

11-1

11.0 POLLUTANT LOADINGS AND COSTS TO MANAGE WASTEWATER

FROM AIRPORT DEICING OPERATIONS

EPA evaluated the effectiveness of implementing an effluent guideline to control

discharges of wastewater from aircraft deicing/anti-icing operations. EPA developed estimates of

pollutant loadings in wastewater discharges from aircraft deicing/anti-icing operations and

loadings in storm water discharges from these operations using the current storm water permit

regulations as a basis of comparison.

EPA did not consider pollutant loadings in storm water discharges from pavement

deicing/anti-icing because EPA believes that, as a result of the implementation of the storm water

permit regulations, increased use of alternate agents that contain no glycol and minimal

biochemical oxygen demand (BOD) load will continue. Consequently, EPA did not account for

loadings from pavement deicers in this analysis. 

Estimates of pollutant loadings were developed for the following four cases:

1. Estimated pollutant loadings prior to implementation of the EPA Phase I

Storm Water Permit Application Regulations;

2. Estimated current pollutant loadings;

3. Estimated pollutant loadings when storm water permits have been fully

implemented; and

4. Estimated pollutant loadings assuming implementation of an effluent

guideline.

Section 11.1 describes the methodology used to develop pollutant loadings and

presents the results. Section 11.2 provides costing information for managing wastewater from

airport deicing operations.
Section 11.0 - Pollutant Loadings and Costs

11-2

11.1 Pollutant Loading Estimates

Aircraft deicing and anti-icing operations are conducted at passenger terminal

gates and aircraft parking ramps where aircraft deicing/anti-icing fluid (ADF) applied to aircraft

falls on the pavement, commingles with storm water, and discharges to U.S. surface waters via

storm water drainage systems. Some airports collect wastewater from aircraft deicing/anti-icing

areas for discharge to publicly owned treatment works (POTWs). Other sources of ADF

discharges include leaks from worn or defective fittings on deicer trucks and other application

equipment; spills such as overfilling deicer truck tanks, leaks from fluid storage tanks; drips from

aircraft during taxiing and takeoff; leaks from containment and collection structures; and leaks

from wastewater storage facilities. While these other sources undoubtedly contribute to pollutant

loadings, EPA believes their combined contribution is minor compared to that from the spray

application of the fluids. EPA, therefore, developed pollutant loading estimates for the industry

based solely on estimates of the average volume of fluid sprayed and considered all other sources

of ADF discharges to be negligible. 

EPA developed pollutant loading estimates using the following six-step method. 

1. Compiled a list of U.S. airports that potentially perform a significant

number of deicing/anti-icing operations and grouped these airports based

on their size and climate. 

2. Estimated the total annual volume of fluid used at each airport identified in

Step 1 using fluid use data collected from the industry. 

3. Estimated the percentage of the fluid sprayed that has the potential to

impact U.S. surface waters and calculated the volume of ADF discharged

annually to U.S. surface waters for each airport identified in Step 1. 

4. Used the estimated volumes calculated in Step 3 combined with

information collected from the industry to estimate the pollutant loadings

discharged to U.S. surface waters prior to the implementation of EPA’s

Phase I Storm Water Permit Application Regulations.
Section 11.0 - Pollutant Loadings and Costs

11-3

5. Used the estimated volumes calculated in Step 3 combined with

information collected from the industry to estimate the current pollutant

loadings and the loadings remaining after full implementation of the Phase I

Storm Water Permit Application Regulations.

6. Estimated the pollutant loadings assuming implementation of an effluent

guideline.

The following subsections describe Steps 1 through 6. The report entitled Development of

Estimated Loadings in Wastewater Discharges From Aircraft Deicing/Anti-icing Operations

describes EPA’s methodology in greater detail and presents airport-specific estimates (1).

11.1.1 Airport Groups (Step 1)

As described in Section 4.3.1.1, EPA identified 212 airports that potentially

perform significant airport deicing/anti-icing operations and arranged them into 20 Airport

Groups based on operations and snowfall characteristics. EPA used the 20 Airport Groups to

estimate fluid use for airports for which fluid use data were not available (as described in Section

11.1.2).

11.1.2 Fluid Use Estimates (Step 2)

Although EPA would have preferred to use actual ADF use data for all airports

identified as potentially performing significant deicing/anti-icing operations, EPA was unable to

do so because it would have required a large number of airports to submit detailed ADF use data. 

Under the Paper Work Reduction Act, this type of request would require U.S. Office of

Management and Budget approval, a process that could not have been completed within the study

schedule. Also, EPA realized that many U.S. airports have not collected ADF use data from their

tenants for previous seasons. 

EPA was able to collect a limited amount of ADF use data directly from airports. 

To supplement these data, EPA requested national estimates of fluid use data from industry
Section 11.0 - Pollutant Loadings and Costs

11-4

airport and airline trade associations. Unfortunately, EPA did not receive any fluid use data from

these organizations; thus, the national estimated fluid use for airports was estimated based on the

airport data collected by EPA under this study.

These data were provided by respondents to EPA’s 1999 Airport MiniQuestionnaire and by airport authorities during site visits, and consisted of data from 23 U.S.

airports. The airports submitted fluid use data in a variety of formats. Several airports provided

fluid use data by glycol base (i.e., ethylene glycol and propylene glycol) and fluid type (i.e., Type

I, Type II (if applicable) and Type IV). For Type I fluids, some airports reported the volume as a

Type I concentrate, while others reported the volume as diluted (i.e., ready-to-use) Type I fluid.

A few airports provided fluid use data by glycol base, but not by fluid type. To simplify this

analysis, EPA converted available ADF use data for each airport to a single common basis,

expressed as Type I fluid at 50% dilution (i.e., as applied). EPA’s data conversion methodology

is illustrated below using data from the following airports as examples.

Des Moines International Airport, Des Moines, IA (DSM)

This airport provided fluid use data for three consecutive deicing seasons for Type

I propylene glycol-based fluid, Type I ethylene glycol-based fluid, Type IV propylene glycolbased fluid, and Type IV ethylene glycol-based fluid. The volumes reported for Type I fluids

were for 50% ADF solutions. For each year, EPA calculated the total volume used by adding the

volumes of each fluid type and glycol base. EPA then averaged the annual totals to determine the

average total annual ADF use.

EPA recognizes that Type II/IV fluids are greater than 50% ADF solutions. 

Therefore, EPA’s simplification to sum Type II/IV fluid volumes into the total as though it were a

50% ADF solution results in a low ADF use bias. EPA believes this bias is not significant because

typically less than 10% of ADF use is Type II/IV fluids.
Section 11.0 - Pollutant Loadings and Costs

11-5

Anchorage International Airport, Anchorage, AK (ANC)

Anchorage International Airport submitted fluid use data for two deicing seasons

by glycol base, but not by fluid type. The fluid volumes were reported as concentrated ADF

solutions. For each deicing season, EPA calculated the total volume of concentrated fluid used by

adding the volumes reported for ethylene glycol-based fluid and propylene glycol-based fluid.

EPA then averaged the annual totals to determine the average total annual ADF use. Finally,

EPA multiplied the average ADF use by two to convert to a 50% ADF solution basis.

To estimate fluid use for airports for which no data were available, EPA developed

fluid use factors. EPA divided the total ADF volume calculated for each airport for which data

were available by the total number of aircraft operations performed at the airport and used the

result to calculate fluid use factors. For some Airport Groups, fluid use data were available for

two or more of the airports in the group. For airports in these groups, EPA calculated an average

fluid use factor to represent the group. Fluid use factors could not be calculated for some Airport

Groups because no fluid use data were available for airports in these groups. In these cases, EPA

estimated fluid use factors based on an engineering assessment of the fluid use factors calculated

for other Airport Groups. 

Note that the fluid use factors described in this section do not represent fluid use

per aircraft deicing/anti-icing operation. For example, the number of annual operations used to

calculate the fluid use factors include operations outside of the deicing season, and not all

operations during the deicing season correspond to deicing/anti-icing operations. Instead, the

fluid use factors are solely for the purpose of normalizing fluid use data among airports of similar

size and climate. 

Fluid use factors for each Airport Group were then used to estimate fluid use at

airports for which fluid use data were not available. For example, the volume of fluid used at 
Section 11.0 - Pollutant Loadings and Costs

11-6

airports assigned to a given Airport Group was estimated by multiplying the total annual aircraft

operations for each airport by the fluid use factor (in gallons of ADF per operation) for the group. 

11.1.3 Estimated Annual Volume of Fluid That Has the Potential to Impact U.S.

Surface Waters and POTWs (Step 3) 

Not all the fluid sprayed has the potential to impact U.S. surface waters and

POTWs since some of the fluid will be lost to the air during spray application, some will remain

on the aircraft, and some will be retained in adjacent grassy areas. EPA assumes that only the

volume of fluid falling on paved deicing/anti-icing areas has the potential to impact U.S. surface

waters and POTWs. Estimates developed by Environment Canada in the early 1980s suggested

that the percentage of fluid falling on paved deicing/anti-icing areas could be as low as 50 percent

(2). More recent research conducted by Limno-Tech, Inc., an environmental consulting company

assisting airports with ADF-contaminated storm water management, indicates that for Type I

fluids, approximately 80% of the fluid sprayed falls on paved deicing/anti-icing areas (3). Based

on fluid use and fluid collection data provided by several U.S. airports, EPA believes that the

more recent estimate made by Limno-Tech is more accurate than the estimate developed by

Environment Canada. 

For each airport, EPA calculated the estimated annual volume of fluid that has the

potential to impact U.S. surface waters and POTWs by multiplying the estimated annual ADF

volume used at the airport by 0.8.

11.1.4 Estimated Annual Volume of Aircraft Deicing/Anti-icing Fluid Discharged

Prior to the Implementation of EPA’s Phase I Storm Water Permit

Application Regulations (Step 4)

EPA does not have sufficient fluid use data to directly calculate pollutant loadings

discharged prior to implementing the Phase I storm water permit application regulations. As a

result, EPA instead estimated these loadings using current ADF use data and other available

information. 
Section 11.0 - Pollutant Loadings and Costs

11-7

EPA knows of no airport or airport tenant that implemented wastewater

containment and collection practices specifically for wastewater generated from aircraft deicing/

anti-icing operations prior to EPA’s publication of the storm water permit application regulations

on November 16, 1990. Consequently, EPA assumed that no U.S. airports managed wastewater

specifically from aircraft deicing/anti-icing operations prior to 1990 (i.e., all U.S. airports were

direct dischargers) and that all U.S. airports would have continued to be direct dischargers if

EPA’s storm water program had not been promulgated. 

EPA estimated the pollutant loadings for the 212 airports that potentially perform

significant deicing operations by summing the estimated volume of fluid that has the potential to

impact U.S. surface waters and POTWs (discussed in Section 11.1.3) and converting the result to

pounds of ADF as applied. The results indicate that an estimated 28 million gallons of ADF (50%

concentration) were discharged annually to surface waters (with zero gallons discharged to

POTWs) prior to the implementation of EPA’s Phase I Storm Water Permit Application

Regulations. EPA believes that this estimate has a high bias because it reflects increased ADF use

since 1990 caused by FAA’s 1992 amendments to the aircraft deicing regulations and by industry

growth. EPA believes it is appropriate to include this bias to enable comparison to the pollutant

loadings estimates developed in Section 11.1.5 (for current loadings) and 11.1.6 (for loadings

after implementation of an effluent guideline), which also reflect increased ADF use since 1990.

11.1.5 Estimated Annual Volume of Aircraft Deicing/Anti-icing Fluid Currently

Discharged (Step 5)

EPA reviewed all currently available information, including that collected from site

visits, industry conferences, questionnaires, and literature sources, to identify airports currently

collecting or otherwise managing wastewater from aircraft deicing/anti-icing operations. EPA

evaluated the efficiency of ADF wastewater management systems currently used at U.S. airports

and used this information to develop four categories of wastewater management performance as

shown below:
Section 11.0 - Pollutant Loadings and Costs

11-8

C Category 1 - Airports with exemplary collection systems capable of

collecting an average of 87.5% of the ADF that would potentially impact

U.S. surface waters (i.e., 70% of fluid applied).

C Category 2 - Airports with collection systems capable of collecting an

average of 51.25% of the ADF that would potentially impact U.S. surface

waters.

C Category 3 - Airports that have implemented some type of wastewater

collection system, but the system is either incomplete or limited in area. 

These airports are capable of collecting an average of 25% of the ADF that

would potentially impact U.S. surface waters.

C Category 4 - Airports that have no provisions for collecting and treating

wastewater from ADF operations (i.e., 0% collection).

All of the airports identified as potentially performing significant aircraft

deicing/anti-icing operations were assigned to one of the four wastewater management

performance categories based on a review of their ADF wastewater management systems. In this

context, management includes wastewater collection systems with either on-site treatment

(including glycol recycling) or controlled discharge to a POTW. 

EPA estimated the total volume of ADF discharged to U.S. surface waters and

POTWs for the 212 airports that potentially perform significant deicing operations by summing

the estimated volume of fluid that is not collected for each airport. The results indicate that an

estimated 21 million gallons of ADF (50% concentration) are currently discharged directly to

surface waters. This represents a 25% reduction from pre-storm-water program estimates. EPA

estimates an additional 2.1 million gallons of ADF (50% concentration) are currently discharged

to POTWs.

EPA estimates that ADF discharges will be further reduced to an estimated 17

million gallons of ADF (50% concentration) discharged directly to surface waters when the

requirements of all storm water permits are fully implemented. EPA also expects the volume of

ADF discharges to POTWs to steadily increase. EPA’s estimate of the discharges associated with
Section 11.0 - Pollutant Loadings and Costs

11-9

full implementation of storm water permit regulations are based on the assumptions that Category

3 airports will implement Category 2 levels of control and that Category 4 airports will implement

Category 3 levels of control.

11.1.6 Estimated Annual Volume of Aircraft Deicing/Anti-icing Fluid Discharged to

U.S. Surface Waters After Implementation of an Effluent Guideline (Step 6)

To estimate the impact of an effluent guideline, EPA assumed that all U.S. airports

identified as potentially performing significant aircraft deicing/anti-icing operations would

implement wastewater management programs that have collection efficiencies comparable to the

Category 1 airports. EPA calculated the total volume of ADF that would be discharged by the

212 airports that potentially perform significant deicing operations (assuming 100%

implementation) by summing the estimated volume of fluid that would not be collected at each

airport. The results indicate that an estimated 3.6 million gallons of ADF (50% concentration)

would be discharged directly to surface waters following the implementation of an effluent

guideline. This represents an 87% reduction from the pre-storm-water permit regulation

estimates and a 62% reduction from current estimates.

An unknown portion of the additional 62% reduction in direct discharges to U.S.

surface waters from current estimates would be discharged to POTWs. This portion would be

dependent on the specific ADF collection and mitigation systems implemented by individual

airports. 

EPA’s estimates of the annual ADF volume discharged by airports that potentially

perform significant deicing/anti-icing operations for each of the three regulatory scenarios are

summarized below. 
Section 11.0 - Pollutant Loadings and Costs

11-10

Case (million gallons/yr) (million gallons/yr)

Estimated Volume of ADF Estimated Volume of ADF

Discharged to U.S. Surface Waters Discharged to POTWs 

Discharges prior to implementation 28 0

of EPA’s Storm Water Program

Current discharges 21 2.1

Discharges following full 17 >2.1

implementation of storm water

permit regulations

Discharges following 3.6 >2.1

implementation of an effluent

guideline

11.1.7 Pollutant Loading Estimates

EPA calculated pollutant loadings using the estimated total ADF volumes

discharged and converting to pounds of ADF and to pounds of BOD . Since the biochemical 5

oxygen demand for Type I fluids differs depending on the glycol-base, EPA calculated a range the

for the pounds of BOD5 using BOD5 data for propylene glycol-based and ethylene glycol-based

Type I fluids. The following table summarizes the pollutant loadings to U.S. surface waters and

POTWs.

Case (million lbs/yr) (million lbs/yr) (million lbs/yr) (million lbs/yr)

Estimated Loadings Discharged to Estimated Loadings Discharged to

U.S. Surface Waters POTWs

ADF Concentrate BOD5 Range ADF Concentrate BOD5 Range

Discharges prior to 126 98 - 102 0 0

implementation of EPA’s

Storm Water Program

Current discharges 95 74 - 77 9.6 7.4 - 7.8

Discharges following full 75 58 - 61 >9.6 >7.4

implementation of storm water

permit regulations

Discharges following 16 12 - 13 >9.6 >7.4

implementation of an effluent

guideline
Section 11.0 - Pollutant Loadings and Costs

11-11

11.2 Costs to Manage Wastewater from Airport Deicing Operations

This section provides costing information for airports that have upgraded their

management systems to control wastewater from airport deicing operations. The available cost

data from airports is summarized below. The Airport Group for each airport is listed as a means

for comparison among airports that would be expected to have similar ADF use, and the

Wastewater Management Category is listed to compare airport costs by current estimated ADFcapture efficiency. 

Airport Management Capital Cost Annual

Group Category Airport (Year Installed) Operating Cost

A1 1 Denver International (DIA) $36 million (1995) $550,000

A2 2 Minneapolis-St. Paul International (MSP) $1.75 million (1993) $1.4 million

2 Chicago O’Hare International (ORD) $98 million (1996) $1 million

A4 2 Dallas/Ft. Worth International (DFW) $1.7 million (1997) Not available

B2 2 Salt Lake City International (SLC) $27.8 million (1998) $760,000

1 Baltimore/Washington International (BWI) $22 million (1997) Not available

C2 2 Bradley International (BDL) $17.7 million (1999) Not available

2 General Mitchell International (MKE) Not available $1 million

C3 3 Kansas City International $8.5 million (1999) Not available

D1 1 Albany International $30.25 million (1989- $325,000

1998)

1 Greater Buffalo International $5.6 million (1996) $100,000

E2 1 Greater Rockford $1.8 million (1994) $176,000

Tables 11-1 and 11-2 at the end of this section list specific capital and annual

operating costs, respectively, provided by airports, vendors, and other contacts. EPA obtained

these costs through EPA-sponsored meetings, industry conferences, EPA mini-questionnaires,

EPA site visits, and other data submittals provided at EPA’s request. These tables provide capital

costs for specific components of storm water management systems and annual costs for specific

types of operating costs (e.g., labor and electricity). These tables may not represent the full range
Section 11.0 - Pollutant Loadings and Costs

11-12

of costs that airports may incur when designing, installing, and operating a comprehensive

management system for wastewater from airport deicing operations.

Section 14.2.3 describes airline deicing costs by major component, including costs

of delay, labor and operating costs, materials, and capital costs.

11.3 References

1. Eastern Research Group, Inc. Development of Estimated Loadings in Wastewater

Discharges From Aircraft Deicing/Anti-icing Operations. December 1999 (DCN

T11074).

2. Transport Canada. State of the Art Report on Aircraft Deicing/Anti-icing.

November 1985 (DCN T10669).

3. University of Massachusetts. Workshop: Best Management Practices for Airport

Deicing. July 1999 (DCN 10661).
11-13

Section 11.0 - Pollutant Loadings and Costs

Table 11-1

Capital Costs Incurred by Airports for Management of Wastewater from Airport Deicing Operations

Airport/Source Description of Management Project Equipment Acquired Capital Costs

Year Construction

Completed or

Dallas/Ft. Worth International Two 3-million-gallon detention ponds with liners and covers; pumping 1997 $1.7 million

Airport (DFW) station; diversion box; and grit chamber with oil skimmer 

Minneapolis-St. Paul Three 1-million-gallon storage ponds with liner, leak detection system, and 1993 $1 million

International Airport (MSP) monitoring wells; an operations center with boiler and recirculation pump

for preventing wastewater freezing 

Elgin vacuum trucks Unknown $275,000 each

Kansas City International Airport Trench drains around passenger terminals; a diversion box; two 1-million- Under construction $8.5 million

(MCI) gallon concrete wastewater storage basins; modifications to the Todd Creek (estimated)

Wastewater Treatment Plant 

Denver International Airport Wastewater collection system for nine aircraft deicing pads and United 1995 $36 million

(DIA) Airlines gates; three 420,000-gallon wastewater storage tanks; two

detention ponds (total capacity 12 million gallons; ADSI glycol recycling

plant; glycol storage tanks 

Albany International Airport Elgin vacuum truck Unknown $248,000

(ALB)

Retrofitting 16 deicer trucks with dripless fittings and automatic filling Unknown $4,000

shut-off valves 

Construction of a wastewater collection system at passenger terminals and 1989 $10 million

two lined lagoons (one 6-million-gallon lagoon and one 2.3-million-gallon

lagoon)

Improvements to the wastewater collection system and construction of a 1989 to Present $20 million

wastewater treatment facility (designed and operated by EFX; see EFX

entry later in this table) Improvements to the collection system included:

blowers and a recirculation pump for the lagoons; a 2.5-million-gallon tank

for wastewater storage; two wet wells (60,000 gallon and 80,000 gallon)

with float activated pumps; and four 4,000-gallon portable tanks for storage

of wastewater with high glycol content 
11-14

Section 11.0 - Pollutant Loadings and Costs

Table 11-1 (Continued)

Airport/Source Description of Management Project Equipment Acquired Capital Costs

Year Construction

Completed or

Greater Rockford Airport (RFD) Wastewater treatment facility (includes a 16-million-gallon lined detention 1994 $1.8 million

pond aerated with four mechanical and 12 aspirating aerators, a

recirculation pump, a 5-million-gallon lined settling pond, two 50,000-

gallon static inclined plate, oil/water separators, and storage building) 

Bradley International Airport Two TennantTM vacuum trucks 1990 $140,000

(BDL) One truck-mounted Ramp RangerTM Unknown $211,000

One trailer-mounted Ramp RangerTM Unknown $180,000

One AR Plus InterceptorTM Unknown $200,000

Construction of deicing pad including three aircraft deicing stations, a Summer 1999 $17 million

deicing pad control tower, ADF storage area with five 20,000-gallon ADF (estimated)

storage tanks, a siamese drainage collection system with automated drain

valves, and two 1-million-gallon underground storage tanks 

Buffalo-Niagara International Installation of storm drain valves and coating pavement surface with a 1995 $1.2 million

Airport (BUF) sealant (cargo and GA facilities only) 

Construction of an underground storm water pipe for conveying November 1999 $4.2 million

wastewater from the cargo area to a contaminated wastewater storage (estimated)

basin. Also includes the enlargement of the underground wastewater

storage basin from its current capacity of 200,000 gallons to a capacity of

approximately 1 million gallons 

Chicago O’Hare International Snow dump improvements including concrete pad, drainage collection Planned $435,000

Airport (ORD) system, and piping to existing detention ponds (estimated)

Construction of hold pad with drainage collection system and a lined 1996 $10 million

detention pond 

Expansion of wastewater storage facility at North Detention Pond including Planned $80 million

two additional detention ponds and junction control chambers; installation (estimated)

of a drainage collection system for north airfield and aircraft maintenance

hangars

Four aboveground storage tanks for ADF with containment structures and 1996 $3.3 million

deicer truck filling stations 
11-15

Section 11.0 - Pollutant Loadings and Costs

Table 11-1 (Continued)

Airport/Source Description of Management Project Equipment Acquired Capital Costs

Year Construction

Completed or

Salt Lake City International Six primary aircraft deicing pads; five secondary deicing pads; three 3- 1998 $23 million

Airport (SLC) million-gallon detention ponds with membrane liner and cover; drainage

collection system for deicing pads and passenger terminals (including

piping, diversion boxes, and pumps) 

Wastewater storage tank and deicing pad (GA facility) Unknown $362,000

Glycol recycling plant 1998 $4.5 million

G. Frigon/Dames & Moore Pinch valves Unknown $8,000 -

$16,000/each

Butterfly valves Unknown $1,200/each

EFX EFX anaerobic biological treatment system (not including storm water 1998 $1.6 million

collection and equalization) at Albany International Airport (ALB)

ATA member Ice detection system Unknown $60,000

Large blankets (for wings) Unknown $10,000/aircraft

AR Plus/VQuip Storm drain inserts Unknown $1,200 - $1,800 

High-capacity vacuum unit Unknown $240,000 -

$250,000

Air Canada Wetland for storm water management at Edmonton airport, Alberta, Under construction $1 million

Canada

AR Plus 6" valve InterceptorTM Unknown $600 - $800

3300G Ramp RangerTM Unknown $250,000
11-16

Section 11.0 - Pollutant Loadings and Costs

Table 11-2 

Annual Costs Incurred by Airports for Management of Wastewater from Airport Deicing Operations

Airport/Source Description of Management Project Year Operating Costs

General Mitchell Annual operating costs for vacuum truck and drain valves 1998-1999 $1 million

International Airport (estimated)

(MKE)

Minneapolis-St. Paul Detention pond cleaning and sludge removal (cost per pond) Unknown $2,600

International Airport

(MSP) Annual operating and maintenance costs for holding ponds, boiler, and associated Unknown $270,000

equipment. Also includes monitoring costs, including biannual sampling from

monitoring wells 

Annual costs for storm water monitoring and analytical analysis Unknown $650,000

Annual POTW charges for wastewater treatment Unknown $150,000 - $200,000

Annual wastewater transportation costs (including trucks and labor), Unknown $350,000

installation/removal of sewer plugs, and maintenance of sewer plugs 

Denver International Annual POTW surcharges for BOD, TKN, and hydraulic load Unknown $550,000

Airport (DIA) (estimated)

Buffalo-Niagara Per hour energy costs for operation of InfraTek® Unknown $100

International Airport

(BUF) Annual BOD surcharge from POTW Unknown $1,800 - $2,400

Albany International Annual costs of storm water monitoring at three sites including: (1) quarterly Unknown $50,000

Airport (ALB) monitoring for volatile organics (benzene, toluene, and xylene) and semivolatile (estimate)

organics; and (2) daily monitoring for glycol from October to May 
11-17

Section 11.0 - Pollutant Loadings and Costs

Table 11-2 (Continued)

Airport/Source Description of Management Project Year Operating Costs

Albany International Annual electricity for aeration of lagoons 1996 $80,633

Airport (ALB) (cont.) 1995 $76,187

1994 $79,823

1993 $100,959

1992 $122,557

1991 $61,561

Albany County Sewer District glycol/BOD annual disposal charges 1997 $15,756

1996 $289,545

1995 $220,381

1994 $299,341

1993 $277,369

1992 $132,815

1991 $121,044

Village of Colonie annual conveyance fees 1996 $180,620

1995 $143,665

1994 $166,946

1993 $173,318

1992 $109,791

1991 $93,217

Greater Rockford Airport Annual operating costs (e.g. electricity, chemicals) for operation of the airport’s 1998 $108,000

(RFD) wastewater treatment facility 

Annual labor costs for operation of the airport’s wastewater treatment facility 1998 $60,000 - $75,000

Chicago O’Hare Per hour cost of leasing and operating Aero SnowTM portable snow melters (per 1998-1999 $6,000

International Airport unit) 

(ORD) Annual POTW disposal costs Unknown $800,000 - $1 million
11-18

Section 11.0 - Pollutant Loadings and Costs

Table 11-2 (Continued)

Airport/Source Description of Management Project Year Operating Costs

Salt Lake City Operating expenses for recycling plant 1998-1999 $760,000

International Airport

(SLC)

Dallas/Ft. Worth POTW surcharge for discharges that exceed BOD limit Unknown $0.08/lb BOD

International Airport

(DFW) POTW charges Unknown $1.07/1,000 gallons

FAA Operating the InfraTek® system at Rochester International Airport Unknown $200 - $500/aircraft

AR Plus 3300G Ramp RangerTM hourly operation Unknown $100 - $110/hr of operation

2800 InterceptorTM rental Unknown $3,500/mo (1-year rental

agreement)

Unknown $1,850/mo (3-year rental

agreement)

Unknown $1,200/mo (5-year rental

agreement)

3300 Ramp RangerTM rental Unknown $19,500/mo 

(1-year rental agreement)

Unknown $10,320/mo 

(3-year rental agreement)

Unknown $6,770/mo 

(5-year rental agreement)

T4000 Ramp RangerTM rental Unknown $5,215/mo 

(1-year rental agreement)

Unknown $2,765/mo 

(3-year rental agreement)

Unknown $1,815/mo 

(5-year rental agreement)

Catch basin inserts Unknown $27.30/mo 

(3-year rental agreement)

Unknown $18.75/mo 

(5-year rental agreement)
11-19

Section 11.0 - Pollutant Loadings and Costs

Table 11-2 (Continued)

Airport/Source Description of Management Project Year Operating Costs

AR Plus (cont.) Wastewater treatment costs based on concentration of glycol in collected Unknown No charge (>20% glycol)

wastewater Unknown $0.07/gal (16 - 20%)

Unknown $0.09/gal (11 - 15%)

Unknown $0.12/gal (6 - 10%)

Unknown $0.15/gal (3 - 5%)

Unknown $0.18/gal (<3%)

Personnel costs Unknown $45/hour (project supervisor)

Unknown $35/hour (equipment operator)

Unknown $30/hour (field technician)

Air Canada Wastewater treatment costs for Vancouver Int’l at Seattle POTW 1999 $0.15/L of wastewater

EFX EFX anaerobic biological treatment system @ 200 GPM and influent of 2,000 Unknown <$3.00/1,000 gallons (annualized)

mg/L of COD (includes amortized capital and annual operating costs)
Section 12.0 - Trends in the Industry

12-1

12.0 TRENDS IN THE INDUSTRY

This section describes trends in the aircraft and pavement deicing industry,

including types and amounts of aircraft deicing/anti-icing fluids (ADFs) used (Section 12.1), types

and amounts of pavement deicing/anti-icing agents used (Section 12.2), deicing/anti-icing

equipment and operations (Section 12.3), and mitigation of wastewater containing spent

deicing/anti-icing agents (Section 12.4). (Economic trends within the air transportation industry,

including airports and airlines, are described throughout Section 14.0 and specifically within

Section 14.2.4.) These trends demonstrate a greatly increased awareness within the past decade

of deicing issues and their potential impacts on the environment by airlines, airports, the EPA and

other regulatory agencies, and the public.

All of the apparent trends discussed in this section are based on information

obtained during EPA’s data-collection activities and subsequent analyses, which are described

throughout this report. Note, however, that the vast majority of these sources are not statistically

reliable. Accordingly, the trends described in this section should be considered qualitative or

anecdotal because available data are insufficient to validate trends statistically. Appendix A

contains information regarding the location of airports referenced in this section.

12.1 Trends in the Use of Aircraft Deicing/Anti-icing Fluids

Based on the limited quantitative data available to EPA, propylene glycol-based

rather than ethylene glycol-based ADFs are now predominantly used in the U.S. This is a large

shift from the status of the industry 10 years prior. This is demonstrated by a letter from the Air

Transport Association (ATA) dated March 1989, “Ethylene glycol is the dominant deicer in use

by airlines in the U.S. today.... Propylene glycol is an anti-icer that is receiving increasing use

because it protects aircraft surfaces for a longer period after application, and because a market

shortage of ethylene has introduced supply and cost problems for ethylene glycol” (1). 
Section 12.0 - Trends in the Industry

12-2

The shift toward using anti-icing fluids in combination with Type I fluids is

demonstrated by an EPA report dated September 28, 1990, “Presently there are two types of

fluids available to commercial airlines and airport authorities. Type I fluids are used for deicing

only and Type II fluids are used for deicing and anti-icing” (1). Since 1990, fluid manufacturers

have developed two anti-icing fluid types, Types III and IV, and have developed ethylene glycolbased anti-icing chemicals (fluid types are described in Section 4.2.1.1). In fact, Union Carbide,

an ethylene glycol-based ADF manufacturer, first developed Type IV fluids. (Note that Type II

and Type III fluids have since become largely obsolete.)

Three primary factors have influenced changes in the types and quantities of ADFs

used by the industry. First, ethylene glycol is listed as a hazardous air pollutant under the Clean

Air Act and is therefore subject to Comprehensive Environmental Response, Compensation, and

Liability Act (CERCLA) reporting requirements when released in a quantity of more than 5,000

pounds in a 24-hour period. Propylene glycol is not listed as a hazardous air pollutant and is not

reportable under CERCLA. Although airports may qualify for eliminated or reduced reporting

requirements via the federally permitted release exemption (2), many airports have moved from

dominant use of ethylene glycol-based fluids to increased use of propylene glycol-based fluids in

part to avoid the burden associated with recordkeeping and reporting. Note that available toxicity

data presented in Section 9.0 indicate that the base glycols exhibit acute aquatic toxicological

effects at concentrations within the same order of magnitude; however, the formulated fluids vary

by manufacturer. Due to propylene glycol’s lower mammalian toxicity, some airports have

switched to propylene glycol in part to meet demands of consent decrees or local citizen’s groups. 

Second, the use of deicing agents increased dramatically in 1992 and 1993 because

of new Federal Aviation Administration (FAA)-mandated deicing rules developed following a

crash caused by improper deicing at LaGuardia Airport. These regulations prohibit takeoff when

snow, ice, or frost is adhering to wings, propellers, control surfaces, engine inlets, and other

critical surfaces of an aircraft and are referred to as the “clean aircraft concept” (see Section

13.4.1). Typical tests show that 1/32nd of an inch of ice accumulation along the leading edge of

the wing of a large jet or 1/64th of an inch on a smaller aircraft can decrease lift on takeoff from
Section 12.0 - Trends in the Industry

12-3

12% to 24%, depending on the size of the aircraft (3). Several airport operators reported at the

American Association of Airport Executives Conference on Aircraft Deicing, August 23, 1993,

that the annual volume of aircraft deicing fluids used by U.S. airlines increased threefold since the

crash (4). Airlines also increased use of aircraft anti-icing chemicals to extend holding times and

reduce secondary aircraft deicing requirements. Total use of ADFs in the future is likely to

increase due to continued growth of the air transportation industry.

Third, on November 16, 1990, EPA published the National Pollutant Discharge

Elimination System Permit Application Regulations for Storm Water Discharges (see Section

13.1). These regulations require airports with deicing and other industrial activities to obtain a

storm water discharge permit. Although there are several permitting alternatives, all permits

require the development and implementation of a Storm Water Pollution Prevention Plan

specifying pollution prevention and best management practices to control pollutant discharges. 

Consequently, many airlines have further increased use of anti-icing fluids (Type II/IV fluids) to

reduce the overall amount of aircraft deicing chemicals used (see Section 6.2.1). In addition,

glycol recycling to mitigate glycol-contaminated wastewater has proliferated (see Section 6.4). 

As a result, some airports have completely substituted propylene glycol-based fluids for ethylene

glycol-based fluids because most recycling systems cannot separate the two glycols and because

of current strength of the secondary markets for propylene glycol.

EPA obtained recent glycol usage data (of varying quality) from 26 airports. An

analysis of these data substantiates trends since 1990 for increased used of propylene glycol-based

ADFs and of Type II/IV ADFs, as shown in the table below.

Trend 1990 Percentage Percentages

Percentage of Airport ADF Applied

1996 to Present (a)

Average Range of

Use of Propylene Glycol-Based ADFs (data from 21 <50% 78 11 to 100

airports)

Use of Type II/IV ADFs (data from 18 airports) Assumed <1% 6.1 0 to 15

(a) Most data are for the 1996-1997 through the 1998-1999 deicing seasons, although some data include earlier years.
Section 12.0 - Trends in the Industry

12-4

Recent trends in ADF usage are more difficult to characterize. EPA obtained ADF

usage data for multiple years (generally for the 1996-1997, 1997-1998, and 1998-1999 deicing

seasons) for 15 of the 26 airports. The following summarize EPA’s findings regarding trends in

propylene glycol-based fluid use during this period: eight airports reported either no change

(generally because the airports use only propylene glycol-based fluids) or varying usage (i.e., both

increases and decreases) on a percentage basis; three airports reported increasing usage on a

percentage basis; one airport reported decreasing usage on a percentage basis; and three airports

did not provide sufficient data for this analysis. These data suggest that the industry may be

reaching equilibrium in glycol usage in this regard. EPA is aware that airlines are very concerned

that increased substitution of propylene glycol-based ADFs for ethylene glycol-based ADFs could

result in the loss of a diverse, competitive market of formulated fluids.

The following summarize EPA’s findings regarding recent trends in Type II/IV

fluid use: three airports reported either no change (i.e., no use of Type II/IV fluids) or varying

usage (i.e., both increases and decreases) on a percentage basis; eight airports reported increasing

usage on a percentage basis; two airports reported decreasing usage on a percentage basis; and

two airports did not provide sufficient data for this analysis. These data suggest that the industry

is increasing its usage of Type II/IV fluids.

While use of Type II/IV fluids may reduce the total volume of ADF applied at an

airport, spent Type II/IV fluids are more difficult to collect because the fluids are widely dispersed

through dripping and sloughing during the taxi and takeoff of aircraft. “Glycol dripping off

aircraft once it leaves the deicing pads is our biggest challenge,” according to Dan Smith,

environmental scientist at Dayton International Airport (5). Because of this, it may be more

environmentally beneficial for airports with highly efficient spent ADF collection and mitigation

practices to use Type I fluids instead of Type II/IV fluids because Type I fluids are easier to

collect then Type II/IV fluids. However, the increased safety that comes with the extended

protection of the anti-icers may outweigh benefits related to ease of collection.
Section 12.0 - Trends in the Industry

12-5

In an effort to lessen the environmental impacts of spent ADFs, airlines are

pressuring manufacturers to develop more environmentally benign ADFs. ATA is working with

the Society of Automotive Engineers (SAE) to require standardized reporting of environmental

information for all fluid types. (SAE standards for ADFs are described in detail in Section 13.5.)

The proposed revised reporting requirements include data for biochemical oxygen demand

(specifically 5 days and 28 days at 5E C and 20E C), chemical oxygen demand (rather than total

oxygen demand), additional aquatic toxicity testing (specifically Ceriodaphnia dubia as test

organism), and 10 trace metals (rather than four) for which water quality criteria exist. The

ATA/SAE Environmental Workgroup is also considering imposing an aquatic toxicity protocol or

goal that would apply to new fluid formulations. Fluid manufacturers have agreed to continue

working on reducing the aquatic toxicity of their products and to work with SAE to consider

developing an SAE aquatic toxicity protocol (6).

At the Airport Deicing Summit for New York State on March 25, 1999, two

representatives of ADF formulators/manufacturers, one from Octagon Process and one from

Lyondell (formerly ARCO), discussed the status of work toward and impediments to developing

less toxic aircraft deicing/anti-icing fluids. The Octagon representative stated that deicing/antiicing additives now comprise only 0.5% of formulated fluids and that manufacturers and

formulators continue efforts to make their products more environmentally friendly. However, the

representative anticipates only minor incremental improvements in products because of the

following factors:

C The variety of replacement chemical additives is small.

C Some possible chemical additives interact and therefore cannot be

combined.

C Performance standards are complex. For example, a variety of metals and

alloys must be protected from corrosion under a variety of conditions. In

addition, the armed forces wish to use commercial rather than military

deicing fluids, resulting in an even greater variety of exotic alloys and

coatings requiring protection.
Section 12.0 - Trends in the Industry

12-6

C Carcinogenic chemical additives are unacceptable.

C Fluid costs are paramount. Potentially promising alternative freezing point

depressants, such as fish fatty acids, would be prohibitively expensive at an

estimated $100 per gallon.

C Many individual fluid additives perform multiple functions but may be

relatively toxic. These additives could be replaced by multiple, less toxic

additives; however, the combined toxicity of the replacement additives can

be greater than the toxicity of the original additive (7).

12.2 Trends in the Use of Airport Pavement Deicing/Anti-icing Agents

Based on the limited quantitative data available to EPA, potassium acetate is now

predominantly used for pavement deicing/anti-icing in the U.S. This is a change that has occurred

over the past two to three years. The change is demonstrated in an EPA report dated September

28, 1990, “Runway deicing materials are normally ethylene glycol, UCAR (by Union Carbide),

and pelletized urea.... Alternative materials including calcium magnesium acetate (CMA) are

under investigation and used at several airports.” Also in this report, “A solution of potassium

acetate with corrosion inhibitors is under investigation as an alternative to glycol-based

compounds for airside use, especially for runway deicing and anti-icing” (1).

EPA obtained pavement deicer usage data (of varying quality) from 26 airports. 

An analysis of these data substantiate trends since 1990 of decreased use of glycols and urea as

airport deicing/anti-icing agents and increased use of alternative airfield deicers/anti-icers. Only

three airports reported using runway deicing material composed of a mixture of ethylene glycol

(50% to 60%), urea (25% to 40%), water (0% to 25%), and dipotassium phosphate (0% to 3%)

(e.g., UCAR). One airport reported using small amounts of propylene glycol (75 gallons per

year) as a wetting agent for sand.

Fourteen airports reported using urea for pavement deicing within the last three

deicing seasons. Of these, six airports have now either discontinued or are phasing out use of

urea in favor of sodium acetate, sodium formate, or potassium acetate. The remaining eight
Section 12.0 - Trends in the Industry

12-7

airports have not reported plans to discontinue or reduce use of urea. Factors preventing or

inhibiting use of alternative pavement deicing/anti-icing agents at these eight airports include: (1)

concerns about the possible impact of potassium acetate on electrical systems, (2) increased cost

of alternate agents, and (3) greater efficiency of urea.

EPA anticipates that trends toward decreased use of ethylene glycol and urea for

pavement deicing/anti-icing will continue because of concerns of the resulting high pollutant

loadings in runoff, high potential for aquatic toxicity from the degradation of urea, and the high

cost of collecting and mitigating contaminated runoff from paved areas.

12.3 Trends in Deicing/Anti-icing Equipment and Operations

Section 6.2 describes a variety of ADF minimization methods that airports and

airlines may implement. Of these methods, only the use of Type IV anti-icing fluids has gained

apparent wide-spread use throughout the industry, as described in Section 12.1. However,

information available to EPA suggests a trend toward increased use of infrared and forced-air

aircraft deicing systems. Both technologies appear to be moving from the experimental or testing

phase to permanent, commercial use. EPA also anticipates increased use of ice detection systems

for both aircraft and pavement.

Trends among the remaining ADF pollution prevention practices are difficult to

evaluate. Airports and airlines have not yet identified an optimum combination of pollution

prevention and spent fluid mitigation methods. Changes in fluid price, recycled/recovered fluid

secondary markets, and fluid toxicity are also expected to influence the selection of pollutant

control practices and technologies. EPA anticipates that future trends within the industry will

stratify by small versus large airports and by the specific preferences (based on economic

considerations and experience) of major carriers operating at each airport. For example, many

airlines, particularly at their hubs and large stations, blend ADFs to temperature and use a fleet of

enclosed-basket deicing trucks (8, 9).
Section 12.0 - Trends in the Industry

12-8

EPA has limited information on trends in pavement deicing/anti-icing equipment

and operations, other than the increased use of alternative agents described in Section 12.2. EPA

believes that the majority of minimization methods described in Section 6.5.3 are standard

operating procedures at U.S. airports because they save airport resources. EPA is not aware of

any trends in the use of alternative pavement deicing/anti-icing methods described in Section 6.5.2

(e.g., heated pavements).

12.4 Trends in Spent Deicing/Anti-icing Chemical Mitigation

Available data demonstrate an increasing trend toward collecting wastewater

contaminated with ADFs using a combination of the practices described in Section 6.3. EPA is 

aware of several airports that are studying options for collecting contaminated wastewater (e.g.,

General Mitchell International Airport, Washington Dulles International Airport, Ronald Reagan

Washington National Airport, and Portland International Airport). With few exceptions, large

airports that perform significant deicing operations have implemented one or more collection

systems for wastewater contaminated with ADFs (10). Specific collection controls are

determined based largely on cost-effectiveness, which is greatly influenced by airport-specific

considerations such as climate, airport layout, airport operations, existing infrastructure, feasibility

of glycol recovery/recycling (on site or off site), availability and accessibility of land, and the

feasibility of discharging contaminated wastewater to a publicly owned treatment works (POTW).

Collection of ADF-contaminated wastewater has resulted in increased use of the

following wastewater management techniques, including:

C Direct discharge at a controlled rate;

C Indirect discharge at a controlled rate;

C On-site wastewater treatment followed by direct or indirect discharge; and

C On-site or off-site glycol recycling/recovery followed by indirect discharge

of residual wastewater.
Section 12.0 - Trends in the Industry

12-9

Recent trends appear to favor use of glycol recycling/recovery. Prior to 1995,

only Denver’s Stapleton Airport performed glycol recycling/recovery. Today, at least 15 airports

use on-site or off-site glycol recycling/recovery (see Section 6.4). EPA anticipates a growing use

of glycol recycling/recovery as part of a total mitigation strategy as more airports implement

wastewater collection systems and while secondary glycol markets remain strong. Several

vendors offer wastewater collection and recycling/recovery services via leasing agreements that

can be implemented relatively quickly with minimal capital expenditure. However, because

recycling/recovery is generally prohibitively expensive for relatively dilute wastewaters, most

airports must also use alternative discharge or disposal practices for these dilute wastewaters.

Available information also demonstrates a significant increase in indirect discharge

of ADF-contaminated wastewater to a POTW. These include discharges with and without

pretreatment. For example, systems used to recycle/recover glycol from spent ADF currently

operating in the U.S. discharge residual wastewater to a POTW. EPA is also aware of several

more airports that are considering or negotiating discharge of ADF-contaminated wastewater to a

POTW.

EPA is not aware of any airports that operated on-site treatment designed to

control glycol discharges prior to 1994. Today, EPA is aware of at least four airports that

operate or are constructing on-site treatment systems for ADF-contaminated wastewater (see

Section 7.0); however, EPA is not aware of any additional airports considering on-site

wastewater treatment. In general, airports prefer indirect discharge of wastewater to on-site

treatment. Unique instances of high conveyance and discharge fees, the inability of the POTW to

accept ADF-contaminated wastewater, or other site-specific considerations cause airports to

consider on-site treatment. EPA also recognizes that uncertain future regulatory requirements

discourage airports from implementing such capital improvements as on-site wastewater

treatment that may be difficult and expensive to retrofit to new requirements.

In contrast to trends in mitigating ADF-contaminated wastewater, EPA is aware of

only one airport, Chicago O’Hare International Airport, that collects wastewater contaminated
Section 12.0 - Trends in the Industry

12-10

with pavement deicing/anti-icing chemicals from runways and taxiways. EPA is not aware of any

additional airports considering collection of these wastewaters, presumably because of

prohibitively high collection costs. Substitution of glycol-based and urea-based deicing/anti-icing

agents with more environmentally benign agents have greatly reduced environmental incentives to

collect and mitigate these wastewaters.

12.5 References

1. U.S. Environmental Protection Agency. Contractor Report - Guidance for Issuing

NPDES Storm Water Permits for Airports. September 28, 1990 (DCN T00226).

2. Letter from Robert I. Van Heuvelen, U.S. EPA to Robert Van Voorhees and

Carol Lynn Green, Bryan Cave LLP. (DCN T11045).

3. Barry Valentine. What’s the Problem We’re Trying to Solve. The Airport Deicing

Advisor. November 1999 (DCN T11071).

4. U.S. Environmental Protection Agency. Emerging Technology Report: Preliminary

Status of Airplane Deicing Fluid Recovery Systems. September 1995 (DCN

T04674).

5. Bremer, K. “The Three Rs - Reduce, Recover, and Recycle,” Airport Magazine.

March/April 1998 (DCN T10361).

6. Stormwater Subcommittee Presentation to SAE G-12 Fluids Subcommittee.

October 20, 1999 (DCN T11046).

7. Meeting Summary for Albany Aircraft Deicing Summit. March 1999 (DCN

T10542).

8. Meeting Summary between U.S. EPA and Air Transport Association, November

1998 (DCN T10464).

9. Letter from Scott F. Belcher, Air Transport Association to Shari Zuskin Barash,

U.S. EPA. November 4, 1999 (DCN T11063).

10. Eastern Research Group, Inc. Development of Estimated Loadings to the

Environment from Aircraft Deicing/Anti-icing Study. December 1999 (DCN

T11074).
Section 13.0 - Relationship to Other Regulations

13-1

13.0 RELATIONSHIP TO OTHER REGULATIONS

This section discusses other regulations pertaining to deicing/anti-icing operations

at airports. Section 13.1 presents an overview of the EPA Storm Water Program; Section 13.2

discusses other national, state, and local permitting issues; Section 13.3 discusses the Canadian

guidelines for the discharge of aircraft deicing/anti-icing fluids (ADF)-contaminated wastewater;

Section 13.4 discusses Federal Aviation Administration (FAA) regulations for airport and aircraft

deicing/anti-icing operations; and Section 13.5 discusses the SAE standards and the role of

Society of Automotive Engineers (SAE) in establishing safe and effective ADFs. Appendix A

contains information regarding the location of airports referenced in this section.

13.1 EPA Storm Water Program

The 1972 amendments to the Federal Water Pollution Control Act (referred to as

the Clean Water Act or CWA), prohibit the discharge of any pollutant to navigable waters from a

point source unless the discharge is authorized by a National Pollutant Discharge Elimination

System (NPDES) permit. Efforts to improve water quality under the NPDES program have

traditionally and primarily focused on reducing pollutants in industrial process wastewater and

municipal sewage discharges because these sources have represented pressing environmental

problems. However, as pollution control measures were initially developed for these discharges,

it became evident that more diffuse sources (occurring over a wide area) of water pollution, such

as agricultural and urban runoff, were also major causes of water quality problems.

EPA performed several assessments to estimate the impact of diffuse and other

sources on water quality. These included the National Water Quality Inventory Report to

Congress (prepared biennially), America’s Clean Water - The States’ Nonpoint Source

Assessment (performed biennially), and the Nationwide Urban Runoff Program. These studies

determined background levels of pollutants from urban runoff, as well as other sources including

illicit connections, construction site runoff, industrial site runoff, and illegal dumping. The studies
Section 13.0 - Relationship to Other Regulations

13-2

noted that elimination of these other sources could dramatically improve the quality of urban

storm water discharges.

In part, in response to these studies, Congress passed the Water Quality Act of

1987 (WQA), which contains three provisions specifically addressing storm water discharges. 

The central WQA provision governing storm water discharges is WQA Section 405, which alters

the regulatory approach to control pollutants in storm water discharges by adopting a phased and

tiered approach. The new provisions phase in permit application requirements, permit issuance

deadlines, and compliance with permit conditions for different categories of storm water

discharges. WQA Section 405 adds Section 402(p) to the CWA, which imposed a time limited

“moratorium” on permitting of storm water discharges. The legislation also identified five types

of storm water discharges that were subject to the moratorium and required a NPDES permit. 

One type is “discharge associated with industrial activity.”

13.1.1 Storm Water Permit Application Regulations

On November 16, 1990, EPA published the National Pollutant Discharge

Elimination System Permit Application Regulations for Storm Water Discharges (55 FR 47989;

codified in 40 CFR 122). The rule presents a preliminary permitting strategy and permit

application requirements for 11 major industrial classifications, and specifically identified “airport

deicing operations” as industrial activities, the discharge from which require a permit. The rule

also defines storm water to mean storm water runoff, snow-melt runoff, and surface runoff and

drainage (§122.26(b)(13)).

The NPDES rule provided three major options for obtaining permits for storm

water discharges associated with industrial activity: (1) a notice of intent to be covered by a

general permit that provides baseline storm water management practices, (2) group permit

applications, and (3) individual permit applications. EPA envisioned implementing these three

permitting options over time to reflect priorities within given states. EPA intended that issuance

of baseline permits (i.e., issuing one permit to authorize a group of discharges) would be the initial
Section 13.0 - Relationship to Other Regulations

13-3

starting point. As priorities and risks within a state are evaluated, classes of storm water

discharges would be identified for watershed permitting (typically accomplished via general areaspecific permits), industry-specific (group) permitting, or facility-specific (individual) permitting.

On August 16, 1991, September 9, 1992, and September 25, 1992, EPA published

“General Permits for Storm Water Discharges Associated With Industrial Activity” (56 FR 40948

and 57 FR 44438). This general permit included the baseline permit requirements intended to

initially cover most storm water discharges associated with industrial activities in states without

authorized NPDES programs. This permit also served as a model for states with authorized

NPDES programs. Section 13.1.2 describes the general permit requirements in detail. Note that

EPA did not reissue general permits for storm water discharges at facilities located in areas where

EPA is the NPDES permitting authority. Therefore, airports located in these areas that were

covered by general permits are now covered by either group or individual permits. General

permits for airports located in areas with approved state NPDES programs remain in effect.

On November 19, 1993 and September 29, 1995, EPA published requirements for

the “Multi-Sector General Permit” for storm water discharges associated with industry activity

based on group permit applications submitted by storm water dischargers in similarly situated

industries (58 FR 61146 and 60 FR 50804). This permit includes requirements that are specific to

individual industrial sectors. Section 13.1.3 describes in detail the requirements specific to airport

deicing/anti-icing operations.

Group permit applications were filed by entities representing groups of applicants

that were part of the same subcategory or are otherwise sufficiently similar. The applications

identified the participants, and described the industrial activities of participants and why they were

sufficiently similar to be covered by a general permit. The American Association of Airport

Executives (AAAE) prepared and submitted a group permit application including over 700

airports.
Section 13.0 - Relationship to Other Regulations

13-4

EPA received group permit applications from over 1,200 groups representing over

60,000 facilities from most of the major industrial classifications, except construction activities. 

The large number of facilities addressed by the regulatory definition of “storm water discharge

associated with industrial activity” would have placed a tremendous administrative burden on

EPA and states with authorized NPDES programs to issue and administer separate permits for

each of these industrial group applicants. To facilitate the process of developing permits for each

of the 1,200 group applications submitted, EPA classified the groups into 29 industrial sectors, in

which the nature of industrial activity, type of materials handled, and material management

practices used were sufficiently similar for the purposes of developing permits. Each industrial

sector was represented by one or more groups that participated in the group application process. 

Airport deicing operations are included in Industrial Sector S (Vehicle Maintenance Areas,

Equipment Cleaning Areas, or Deicing Area located at Air Transportation Facilities).

NPDES authorities issue individual permits (or modify existing individual permits

to incorporate storm water discharge-related conditions) when warranted by the need for

individual control mechanisms, their potential for pollution prevention, and where reduced

administrative burdens exist. Section 13.1.4 describes in detail the requirements for individual

permit applications.

13.1.2 General Permit (Baseline Industrial General Permit)

Facilities submit a notice of intent (NOI) to be covered by a general permit to

authorize storm water discharges (the deadline for submitting a NOI for existing facilities was

October 1, 1992). The NOI contains basic information such as the name and address of the

facility, the Standard Industrial Classification codes that best represent the principal products or

activities provided by the facility, the facility latitude and longitude, a brief description of the

discharge and receiving water, and an indication of whether they have sampling data available for

storm water discharges. Permits may require additional information where appropriate. Unless

otherwise specified, dischargers are automatically authorized to discharge under the general

permit by submitting an NOI in accordance with the terms of the permit.
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General permit conditions and requirements are summarized below:

C Prohibition of non-storm-water discharges (with some specific exceptions)

and discharges that contain a hazardous substance in excess of reporting

quantities at 40 CFR 117.3 or 40 CFR 302.4.

C Annual monitoring of storm water discharges from aircraft or airport

deicing areas for oil and grease, 5-day biochemical oxygen demand

(BOD ), chemical oxygen demand (COD), total suspended solids (TSS), 5

pH, and the primary ingredient used in the deicing materials (e.g., ethylene

glycol, propylene glycol, ammonia) for airports with over 50,000 flight

operations per year. Other airports are not required to conduct discharge

monitoring unless required by the permitting authority.

C Facilities are subject to record-keeping requirements, but generally do not

have reporting requirements. (NOI provisions for reissued permits require

dischargers to summarize the quantitative data collected during the

previous permit term.) Facilities may collect a minimum of one grab

sample from holding ponds or impoundments with a retention period

greater than 24 hours. For all other discharges, both a grab and a

composite sample are required.

C Estimation of the size of the drainage area and runoff coefficient of the

drainage area.

C Preparation, retention, and implementation of a site-specific storm water

pollution prevention plan to minimize and control pollutants. Plan

requirements are based on traditional storm water management, pollution

prevention, and best management practice concepts tailored to storm water

discharges associated with industrial activities, and are imposed in lieu of

numeric effluent limitations. Specific plan requirements are discussed

below.

- Identification of a team responsible for developing the plan and

assisting the plant manager with implementing, maintaining, and

revising the plan.

- Description of activities, materials, and physical features of the

facility that may contribute significant amounts of pollutants to

storm water runoff. The plan must contain a site map showing

storm water drainage, control structures, and areas of potential

pollution sources (e.g., material storage and processing and waste

disposal). It must also include an inventory of exposed materials, a
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list of significant spills and leaks that occurred three years prior to

the effective date of the permit, an evaluation of the presence of

non-storm-water discharges, a description of existing data on the

quality or quantity of storm water discharges, and a risk

identification and summary of potential pollutant sources.

- Evaluation, selection, and description of the pollution prevention

measures, best management practices, and other controls that the

facility will implement. At a minimum, the plan must address good

housekeeping practices, preventive maintenance, spill prevention

and response, inspections, employee training, record-keeping and

internal reporting procedures, sediment and erosion control, and

management of runoff.

- Description of annual comprehensive site compliance evaluations to

confirm the accuracy of the evaluations and descriptions in the plan,

determine the effectiveness of the plan, and assess compliance with

the terms and conditions of the permit.

13.1.3 Multi-Sector General Permit

Group permit applications could have been filed by an entity representing a group

of applicants that were part of the same subcategory or, if such a grouping was not applicable,

were sufficiently similar as to be appropriate for general permit coverage under §122.28. The

permit application consisted of two parts, Part 1, which was due on September 30, 1991, and Part

2, which was due on October 1, 1992. Part 1 included the following:

C Identification of the participants in the group application by precipitation

zone (Appendix E to §122);

C Description of the industrial activities of participants and why they are

significantly similar to be covered by a general permit;

C List of significant stored materials exposed to precipitation and materials

management practices used to diminish contact; and

C Identification of group members who will submit quantitative data and

description of why these selected facilities are representative of the group.
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Part 2 of the permit application included submission of information for each representative facility

equivalent to information that facilities applying for individual permits are required to submit.

AAAE’s group permit application included Part 1 and Part 2 information for 59

airports considered to be representative of the 700 airports comprising the group permit

application. Part 2 of the group application did not specify that facilities must sample storm water

discharges from areas where deicing/anti-icing activities occurred and/or during times when such

operations were conducted. As a result, only one facility indicated that the sampling data

submitted were collected from areas where deicing activities were conducted.

EPA reviewed the group permit application to develop permit requirements

contained in the Multi-Sector General Permit - Section S. Requirements specific to deicing/antiicing operations are described in 60 FR 50998 (September 25, 1995) and include the following:

C Dry weather discharges of deicing/anti-icing chemicals are not authorized

by this permit. There is no limit, however, on the time between a snowfall

and snow-melt for the purpose of including a snow-melt discharge in the

definition of storm water.

C Airports that use more than 100,000 gallons of glycol-based deicing/antiicing chemicals and/or 100 tons of urea on an average annual basis will:

- Prepare estimates for annual pollutant loadings discharged to storm

sewer systems or surface waters, prior to and after implementation

of the facility’s storm water pollution prevention plan.

- Monitor outfalls from the airport that collect runoff from areas

where deicing/anti-icing activities occur for BOD , COD, ammonia, 5

and pH. The airport should monitor these outfalls four times per

year, from December through February when deicing/anti-icing

activities occur, within the second and fourth years after permit

issuance. A minimum of one grab sample and one flow-weighted

composite sample should be collected from each outfall. Sampling

within the fourth year may be waived if sampling data collected

within the second year are less than monitoring cut-off

concentrations of 30 mg/L for BOD5, 120 mg/L for COD, 19 mg/L

for ammonia, and between of 6 and 9 standard units for pH.
Section 13.0 - Relationship to Other Regulations

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- Record precipitation event data.

C The airport will prepare a comprehensive storm water pollution prevention

plan that integrates areas of the facility occupied by airport tenants (i.e.,

co-located industrial activities), regardless of whether or not tenants are

co-permittees. The operator(s)/owner(s) (the airport authority) of the

airport storm water outfalls is (are) ultimately responsible for compliance

with all terms and conditions of this or other NPDES permits applicable to

storm water outfalls. Plan requirements specific to deicing/anti-icing

operations are described below.

- Identification of a team responsible for developing the plan and

assisting facility management in its implementation, maintenance,

and revision.

- Description of potential pollutant sources and a site map indicating

the locations of aircraft and runway deicing/anti-icing operations.

- Description of the potential pollutant sources from aircraft and

runway deicing/anti-icing operations (including apron and

centralized aircraft deicing/anti-icing stations, runways, taxiways,

and ramps) and identification of any pollutant or pollutant

parameter of concern.

- Requirements for facilities that conduct deicing/anti-icing

operations to maintain a record of the types (including the Material

Safety Data Sheets) and monthly quantities of deicing/anti-icing

chemicals used. Tenants and fixed-base operators who conduct

deicing/anti-icing operations will provide records to the airport

authority to include in the comprehensive plan.

- Description of storm water discharge management controls

appropriate for each area of operation and a schedule for

implementing such controls. Specifically, operators who conduct

aircraft and/or runway (including taxiways and ramps) deicing/antiicing operations will consider alternative practices to reduce the

overall amount of deicing/anti-icing chemicals used and/or lessen

environmental impacts.

For runway deicing operations, operators will evaluate: present

application rates to ensure against excessive overapplication;

metered application of deicing chemical; prewetting dry chemical

constituents prior to application; installation of runway ice

detection systems; implementation of anti-icing operations as a
Section 13.0 - Relationship to Other Regulations

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preventive measure against ice buildup; the use of substitute deicing

compounds, such as potassium acetate, in lieu of ethylene glycol,

propylene glycol, and/or urea.

For aircraft deicing operations, operators will evaluate current

application rates and practices to ensure against excessive

overapplication, and consider pretreating aircraft with hot water

before applying a deicing chemical, thus reducing the overall

amount of chemical used per application. Operators will implement

measures determined to be reasonable and appropriate.

- Description of management practices to control or manage

contaminated runoff from areas where deicing/anti-icing operations

occur to reduce the amount of pollutants being discharged from the

site. The airport should consider structural controls such as

establishing a centralized aircraft deicing facility, and/or collection

of contaminated runoff for treatment or recycling. The plan should

consider recovering deicing/anti-icing materials when these

materials are applied during nonprecipitation events to prevent

these materials from later becoming a source of storm water

contamination. The airport will implement and maintain controls

determined to be reasonable and appropriate.

- Inspections of areas where deicing/anti-icing operations are

conducted at least once per week during deicing/anti-icing

application periods.

- Pollution prevention training to inform management and personnel

responsible for implementing activities identified in the storm water

pollution prevention plan of the components and goals of the plan.

- Comprehensive site compliance evaluations at least annually during

periods of deicing/anti-icing operations to ensure that measures to

reduce pollutant loadings are adequately and properly implemented

in accordance with the terms of the permit, and to determine

whether additional control measures are needed.

13.1.4 Individual Permit

Application requirements for individual permits include submitting the appropriate

permit application forms and the following supplemental information:
Section 13.0 - Relationship to Other Regulations

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C A site map of the facility including details of drainage and discharge

structures, drainage areas, and pertinent features of drainage areas of all

storm water outfalls, including paved areas and buildings, significant

material storage and disposal areas, structural control measures, materials

loading and access areas, chemical application areas, and areas associated

with hazardous waste.

C An estimate of the area of impervious surfaces and the total area drained by

each outfall and a description of the pertinent features listed above.

C A certification that all outfalls that should contain storm water discharges

associated with industrial activity have been evaluated for the presence of

non-storm-water discharges.

C Existing information regarding significant leaks or spills of toxic or

hazardous pollutants at the facility that have taken place within three years

of application submittal.

C Quantitative data based on samples collected during storm events from all

outfalls containing storm water discharges associated with industrial

activity. Required sampled parameters include oil and grease, pH, BOD ,5

COD, TSS, total phosphorus, total Kjeldahl nitrogen, nitrate plus nitrite

nitrogen, any pollutant limited in an effluent guideline to which the facility

is subject, any pollutant listed in the facility’s NPDES permit for its process

wastewater (if applicable), and other pollutants as required under

§122.21(g)(7)(iii) and (iv). Samples must be collected in accordance with

§122.21.

C Flow measurements or estimates, and the total amount of discharge for the

storm event(s) sampled.

C The date and duration of the storm event(s) sampled and other related

information.

Based on a review of the permit application, the regulatory authority issues a

facility-specific permit (or modifies an existing permit) to incorporate unique permit requirements. 

Requirements typically include discharge monitoring, implementation of best management

practices, and an assessment of the impacts of these practices.
Section 13.0 - Relationship to Other Regulations

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13.2 National, State, and Local Limitations

This section discusses current national, state, and local regulations pertaining to

the discharge of storm water contaminated with deicing/anti-icing agents.

13.2.1 National Regulations

One of the purposes of this study is to evaluate whether national effluent

limitations guidelines and standards are warranted for deicing/anti-icing operations. The only

national regulations currently applicable to discharges of airport deicing operations wastewater

are EPA’s storm water program (see Section 13.1). Ethylene glycol and propylene glycol,

however, are regulated by EPA and the Food and Drug Administration (FDA) under several

regulations. Ethylene glycol is listed as a Hazardous Air Pollutant (HAP) under the Clean Air Act

Amendments of 1990 (propylene glycol is not). Because ethylene glycol is a HAP, it is

automatically subject to the Comprehensive Environmental Response, Compensation and Liability

Act (CERCLA) and thus reporting requirements. The reportable quantity is 5,000 pounds of

ethylene glycol in a 24-hour period, which converts to approximately 1,200 gallons of Type I

deicing fluid applied as a 50/50 mixture in a 24-hour period. 

Wastewater associated with manufacturing ethylene glycol and propylene glycol is

regulated under different subparts of the effluent limitations guideline for organic chemicals,

plastics, and synthetic fibers (OCPSF). Although the OCPSF guidelines do not apply to ADF

discharges from an airport, effluent limitations have been promulgated for BOD , TSS, and pH for 5

both subparts. The monthly average BOD5 limitations for the manufacture of ethylene glycol and

propylene glycol are 30 mg/L and 34 mg/L, respectively. Manufacturers of ethylene glycol and

propylene glycol are also both regulated under the Clean Air Act under New Source Performance

Standards for the Synthetic Organic Chemical Manufacturing Industry (SOCMI). 

The FDA has established regulations for both glycols. The FDA established that

propylene glycol is “generally recognized as safe” (GRAS) for human consumption; however, it
Section 13.0 - Relationship to Other Regulations

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recently withdrew the GRAS status for the use of propylene glycol in cat food (1). According to

FDA guidelines, ethylene glycol can only be used as an indirect food additive for use in adhesives. 

On an international level, the World Health Organization has set an acceptable daily intake level of

propylene glycol at 0 to 25 mg/kg. 

13.2.2 State and Local Regulations

The CWA includes a number of programs implemented at the state and local levels

aimed at restoring and maintaining water quality. These include state, territorial and authorized

tribal water quality standards; state, territorial and authorized tribal nonpoint source management

programs; state, territorial and authorized tribal water quality monitoring programs; and the

NPDES permit program for point sources. These programs combined with national regulations

have produced significant and widespread improvements in water quality over the last quartercentury, but many water bodies remain impaired by one or more pollutants. For example, the

National Water Quality Inventory Report to Congress for 1996 indicates that of the nation’s

water bodies that have been assessed, approximately 40% of these do not fully support water

quality standards or uses. The major causes of impairments in water bodies include sediments,

nutrients, and pathogens. Other causes include dissolved oxygen, habitat and flow alterations,

pH, metals, mercury, and pesticides. Recent EPA regulatory revisions provide increasing

emphasis on restoring impaired and threatened waters.

Discharge of deicing agent-contaminated storm water from airports is increasingly

controlled by state and local regulations. For example, several states have implemented waterquality guidelines for ethylene glycol; the guidelines vary greatly between states (2). Due to local

limitations and considerations given to receiving streams, airport-specific discharge limits can vary

widely within a given state. For example, two airports, both in New York, comply with vastly

different propylene glycol levels because one airport discharges to a water body that serves as a

drinking water intake and, therefore, has more stringent limits than the other airport, which does

not. Total maximum daily loads (TMDLs), which are water quality-based maximum loadings for

individual streams, can also dictate discharge limits for airports. (TMDLs are described in greater
Section 13.0 - Relationship to Other Regulations

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detail below.) Table 13-1 at the end of this section summarizes airport permit data collected by

EPA for wastewater from airport deicing operations. EPA collected permit data from site visits

and mini questionnaires. EPA also requested permit data from certain airports.

At least nine states have implemented drinking water guidelines and standards for

ethylene glycol. The acceptable ethylene glycol concentration in effluent discharges from these

states ranges from 100 ppb to 14,000 ppb (or 14 mg/L) (2). At least five states have implemented

water quality standards to protect human health or aquatic life, and the acceptable ethylene glycol

concentration from these states ranges from 7 ppb to 19,000 ppb (2). EPA was able to identify

only one state, New York, that has implemented a drinking water standard for propylene glycol. 

The state Health Department establishes maximum concentration levels (MCLs) that are

protective of public water supplies in New York State. The MCL for propylene glycol was

recently revised from 50 ppb to 10,000 ppb (or 10 mg/L) (3). 

Although not specifically developed to control the discharges from airport deicing

operations, water quality standards for BOD or dissolved oxygen have been widely implemented

throughout many states. As a result, permit writers may be indirectly controlling the discharge of

ADF-contaminated wastewater by considering the acceptable oxygen levels in the receiving

stream. 

Airports that discharge to impaired water bodies may be required to meet NPDES

permit limits designed to achieve total maximum daily loads (TMDLs). A TMDL specifies the

maximum amount of a pollutant that a water body can receive and still meet water quality

standards (including a margin of safety and consideration of seasonal variations), and allocates

pollutant loadings among point and nonpoint pollutant sources. Section 303(d) of the CWA

requires states, territories, and authorized tribes to identify and establish a priority ranking for

waters for which existing pollution controls are not stringent enough to attain and maintain water

quality standards. EPA intends that TMDLs be established over a 15-year timeframe with

TMDLs for the most impaired water bodies established earlier in this timeframe. Priorities must

take into consideration the severity of the pollution and uses of the water bodies (e.g., drinking
Section 13.0 - Relationship to Other Regulations

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water sources). Although the future impact of TMDLs on airport deicing operations is unknown,

airports discharging to receiving streams with dissolved oxygen or nutrient criteria are most likely

to be affected.

EPA is aware of only one airport, Portland International Airport in Portland,

Oregon, whose NPDES storm water discharge permit incorporates limits based on a TMDL to

attain water quality standards in the Columbia Slough. The permit contains limits reflecting BOD5

waste load allocations to achieve the receiving stream dissolved oxygen criterion. The waste load

allocation increases with increased flow in the Columbia Slough. Discharge monitoring is

required throughout the deicing season (November 1 through April 30) with more frequent

monitoring requirements during and following deicing/anti-icing events. Monitoring is not

required from May 1 through October 31 (4).

Based on EPA’s data-gathering activities, pollutants that airports typically monitor

for in discharges from airport deicing operations to surface waters and/or to POTWs include:

C BOD ;5

C COD;

C TSS;

C Ethylene and/or propylene glycol;

C Copper, lead, and zinc;

C Ammonia as nitrogen; and

C pH.

Many airports are required to monitor only for these pollutants and are not subject to specific

concentration limits or action levels. Many of those airports may only be required to monitor for

some of these pollutants (i.e., not the entire list). However, at airports that have specific

numerical requirements in their permits, limitations are typically placed on BOD5, TSS, ammonia

as nitrogen, glycols, and metals (e.g., copper, lead, zinc). EPA did not identify any airport

currently monitoring specifically for pollutants that may be a component of the ADF additive pack

(e.g., tolyltriazoles). As discussed in Section 9.2, EPA and current ADF researchers believe the

additive pack may be the greatest contributor to the aquatic toxicity exhibited by ADFs. Table
Section 13.0 - Relationship to Other Regulations

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13-2 at the end of this section summarizes the range of limitations for pollutants for which many

airports typically monitor and their associated monitoring frequency. This table does not include

additional permit provisions such as BMPs and structural controls. 

13.3 Canadian Management Measures

In Canada, as in the United States, deicing and anti-icing activities using glycolbased fluids are an important part of winter operations at airports. Unlike the Unites States where

propylene glycol-based fluids dominate, airlines in Canada primarily use ethylene glycol-based

deicing/anti-icing fluids. Based on conversations with Canadian industry and government

representatives, the main reason for using ethylene glycol-based fluids is that ethylene glycol is a

more effective freezing point depressant than propylene glycol at low tempertatures.

In the early 1990's, concern about the detrimental effects of glycols on aquatic

ecosystems led to the development and promulgation of two different glycol guidelines: (1) the

1994 Canadian Environmental Protection Act (CEPA) Part IV Glycol Guidelines, which

established a voluntary guideline recommending discharge limitations for glycol at federal

airports; and (2) the 1997 Canadian Water Quality Guidelines for Glycols, which established a

voluntary guideline recommending safe ambient concentrations from the discharge of glycols into

the environment. These guidelines are described in detail in Sections 13.3.1 and 13.3.2.

In addition to providing environmental protection-based performance targets, the

guidelines are designed to assist facilities in promoting compliance with the general pollution

prohibitions of the [Canadian] Fisheries Act. The Fisheries Act Section 36(3) (the Act) requires

that “no person shall deposit or permit the deposit of a deleterious substance of any type in water

frequented by fish or in any place under any conditions where the deleterious substance or any

other deleterious substance that results from the deposit of the deleterious substance may enter

such water.” A deleterious substance is defined as “any substance that, if added to any water

would degrade or alter...the quality of that water so that it is rendered deleterious to fish or fish

habitat...” Ethylene glycol and propylene glycol as well as formulated ADFs may be considered
Section 13.0 - Relationship to Other Regulations

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deleterious substances according to its definition in the Act. Individual air carriers are responsible

for deicing their aircraft and ensuring that they are not in violation with local, provincial, or

federal legislation. The Fisheries Act allows individuals to be held responsible for pollution and

imposes criminal penalties such as fines and jail time. Therefore, an air carrier may be in violation

of the Fisheries Act unless a “due diligence” defense (i.e., a reasonable degree of care and

attention was given to avoid harming the environment or humans) is established. Due diligence

may include compliance with the glycol guidelines through glycol pollution prevention and

mitigation efforts, environmental monitoring, audits, etc.

13.3.1 Canadian Environmental Protection Act (CEPA)

CEPA, originally passed in June 1988, is the principle federal legislation aimed at

protecting the environment and the health of Canadians from toxic substances and other

pollutants. Part IV of CEPA gives the Minister of the Environment the authority to regulate

waste handling and disposal practices and emissions and effluents from federal activities. It also

gives the Minister the authority to establish regulations and guidelines that apply to federal lands

where regulatory authority would not otherwise exist. 

In February 1994, EC promulgated voluntary glycol guidelines for deicing

practices at federal airports under Section 53 of CEPA. The guidelines recommend an “end-ofpipe” discharge limit at federal airports and requires that annual reports of the results from

monitoring glycol be prepared after each deicing season. 

Under the National Airports Policy (NAP), announced in 1994, the Canadian

government is commercializing its airports. The largest and busiest airports are being transferred

to Canadian Airport Authorities, while the smaller airports are being offered for sale to local

community interests. There will be 26 airports that will form part of the NAP. The airports will

remain federal property but be operated by an airport authority. Transport Canada will remain the

owner/landlord of these airports. Thus, these airports will be subject to federal regulations and

guidelines, including the CEPA Glycol Guideline. NAP airports include such facilities as
Section 13.0 - Relationship to Other Regulations

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Vancouver, Victoria, Calgary, Edmonton, Winnipeg, Thunder Bay, Toronto, Ottawa, Dorval, and

Montreal-Mirabel.

The glycol guideline established under CEPA sets a 100-mg/L limit for total glycol

allowed at the point of discharge. It is based on the prevention of all impacts to aquatic life as

determined by an assessment of the available information (pre-1994) on the impacts of glycols and

their associated deicing/anti-icing fluids and a review by a multistakeholder working group. The

Minister of the Environment decided upon the final CEPA Glycol Guidelines based on this expert

scientific assessment and the recommendations of the government-industry working group which

included considerations of technological feasibility and socioeconomic factors (5).

Based on the scientific knowledge at that time (pre-1994), the most sensitive effect

level reported in scientific literature was based on a study with the common ciliated protozoan

Chilomonas paramecium. Data gathered from Bringmann et al. (1980) determined that the 48-

hour lowest concentration at which effects were observed (LOEC) for growth inhibition in

Chilomonas paramecium is 112 mg/L of ethylene glycol. Following standard practices, a safety

factor of 0.1 was applied to this lowest effect concentration to derive an acceptable concentration

of approximately 10 mg/L. A safety factor is applied to account for the uncertainties associated

with species-to-species and laboratory-to-field extrapolations. This concentration was then

converted to a discharge concentration assuming an “end-of-pipe” dilution ratio of 1:10, resulting

in the guideline of 100 mg/L. The sampling point for compliance is the airport’s effluent

discharge point to a receiving stream (5).

In 1997, industry requested a review of the CEPA glycol guideline. Following the

review, the 100 mg/L voluntary guideline remains in place. 
Section 13.0 - Relationship to Other Regulations

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13.3.2 Canadian Water Quality Guidelines

The national Canadian Water Quality Guidelines for surface water limits for

glycols are developed and promulgated nationally under the auspices of the Canadian Council of

Ministers for the Environment (CCME). The CCME comprises 14 intergovernmental (i.e.,

federal, territorial, and provincial) ministers and is a forum for discussion and joint action on

environmental issues of national and international concern. Canadian Water Quality Guidelines

are used to protect ecosystems, assess environmental quality problems, and manage competing

uses of water resources. These guidelines do not constitute values for uniform national water

quality and their use requires local water quality considerations. They are updated as new data

become available. Environment Canada serves as the federal member and scientific and technical

secretariat for the CCME guidelines task groups, providing the leadership in science assessments

and drafting proposed guidelines for national review and approval.

Development of the Canadian Water Quality Guidelines program began in 1984. 

In 1987, the Water Quality Guidelines Task Group of the CCME published the Canadian Water

Quality Guidelines for over 100 substances. Since that time, the Group has published revised

guidelines for specific parameters. The guidelines are voluntary, scientifically based, and apply

to all situations where glycols may enter the environment (e.g., releases from aircraft deicing,

automotive coolants, pipeline dehydrators). They provide recommended ambient environmental

concentrations for the protection of aquatic life both for freshwater and marine species. The

current freshwater guideline is set at 192 mg/L for ethylene glycol, and at an interim limit of 500

mg/L for propylene glycol. There is currently no recommended freshwater guideline for

diethylene glycol due to insufficient data, and no recommended marine guideline for ethylene

glycol, propylene glycol, or diethylene glycol due to insufficient data (6).

The current CCME guidelines were derived from acceptable studies from the most

sensitive species exposed to each glycol. Data gathered from the Aeroports de Montreal and

Analex Inc. in 1994 determined that the LOEC for growth inhibition in green algae to be 1,923.5

mg/L for ethylene glycol. A safety factor of 0.1 is applied to the LOEC to establish a water
Section 13.0 - Relationship to Other Regulations

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quality guideline for the protection of freshwater species, which results in the guideline of 192

mg/L. Data gathered from Dufresne and Pillard (1995) determined the 96-h LOEC for frond

growth inhibition in duckweed to be 5,000 mg/L for propylene glycol. Applying the safety factor

of 0.1 results in the guideline of 500 mg/L. The guideline is considered interim due to limited

available data. Additional chronic studies are required to attain full guideline status (6). 

The main difference between the CEPA Glycol Guidelines and the water quality

guideline is how they were derived and where they are applied. The CEPA guidelines apply at the

“end-of-pipe” discharge point at airports, and assume that glycol is combined with non-glycolcontaminated storm water. The limit derivation accounts for dilution. The CCME water quality

guidelines apply to much more than airports, and, as a conservative estimate, do not factor other

non-glycol-contaminated storm water sources into the limit because they were not specifically

derived for airports.

Water quality guidelines for dissolved oxygen were developed as part of the

original guidelines established in 1987 and are summarized below.

Species Life stage Concentration (mg/L)

Minimum Dissolved Oxygen

Freshwater Warm-water biota Early 6

Other 5

Cold-water biota Early 9.5

Other 6.5

Marine All All >8

Source: Reference (6).

However, even at glycol concentrations below the revised CCME guidelines, the ambient oxygen

level may fall below the recommended dissolved oxygen guideline. All CCME jurisdictions

recommend that the dissolved oxygen guidelines be used in conjunction with the glycol guidelines. 
Section 13.0 - Relationship to Other Regulations

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13.4 Federal Aviation Administration Regulations

The FAA is part of the Department of Transportation and is responsible for

regulating and promoting civil aviation. To ensure the safety of air transportation, FAA issues

Federal Aviation Regulations (FARs) and advisory circulars. FARs are published in Title 14 of

the Code of Federal Regulations and are designed to ensure the safe operation of aircraft,

including operation during snow and ice conditions. Advisory circulars provide standards,

specifications, and guidance on a wide range of safety issues including winter operations at

airports. Under the current regulations, carriers (e.g. airlines) and pilots are responsible for

conducting adequate aircraft deicing, while airports are responsible for ensuring that runways,

taxiways, and other aircraft operational areas are properly cleared of snow and ice.

13.4.1 FAA Winter Operating Regulations for Aircraft

Snow, ice, and frost on aircraft surfaces can drastically reduce lift, alter handling

characteristics, and make the aircraft difficult to control. Because of the safety hazard this poses,

FAA has developed regulations that prohibit takeoff when snow, ice, or frost is adhering to wings,

propellers, control surfaces, engine inlets and other critical surfaces of an aircraft. This approach

is referred to as the “clean aircraft concept.” Although FAA regulations for winter operations

differ depending on the size of aircraft and type of operations, all require that snow, ice and frost

be removed from aircraft surfaces prior to takeoff and make the pilot ultimately responsible for

determining the airworthiness of his/her aircraft.

FAA regulations do not stipulate which methods or materials should be used to

remove snow, frost, or ice but recommend that commercial carriers and owners of private aircraft

use methods and materials approved by the Society of Automotive Engineers (SAE) (see Section

13.5). However, the FAA requires that the deicing and anti-icing method selected for a particular

aircraft be approved for use on that aircraft by the aircraft manufacturer. This approach gives the

industry the flexibility to select aircraft deicing and anti-icing methods best suited to their

individual operation. 
Section 13.0 - Relationship to Other Regulations

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The FAA publishes advisory circulars to assist aircraft operators in developing safe

winter operating practices and selecting appropriate aircraft deicing methods. The advisory

circulars provide standards, guidelines, and advice designed to help aircraft operators comply with

aircraft deicing regulations and operate safely in winter weather conditions. Current FAA

advisory circulars recommend that aircraft operators use ethylene glycol- or propylene glycolbased aircraft deicing and anti-icing fluids that meet the standards set by SAE (i.e., SAE-certified

fluids). SAE standards for deicing fluids (i.e., Type I fluids) can be found in Aerospace Material

Specification (AMS) 1424 and for anti-icing fluids (i.e., Types II, III and IV fluids) in AMS 1428. 

SAE provides recommended methods for applying deicing and anti-icing fluids in Aerospace

Recommended Practice (ARP) 4737. 

FAA regulations for winter operations differ depending on the size of the aircraft

and type of operations. The most stringent regulations for aircraft deicing/anti-icing are those for

carriers conducting scheduled commercial operations of passenger and cargo aircraft. Carriers

operating passenger aircraft with more than nine seats, passenger aircraft with turbojet engines,

and cargo aircraft with payload capacities of more than 7,500 pounds must comply with

regulations contained in FAR Part 121, and are commonly referred to as Part 121 carriers. 

Aircraft deicing/anti-icing regulations for these carriers are contained in FAR Part 121.629,

“Operation in Icing Conditions.” This regulation requires Part 121 carriers to follow an FAAapproved aircraft deicing and anti-icing program. Carriers may follow the FAA-approved

procedure or develop their own aircraft deicing plan. The FAA-approved procedure requires

carrier personnel to conduct a pretakeoff contamination check from outside the aircraft within five

minutes of takeoff during conditions in which ice, frost, or snow may adhere to aircraft surfaces. 

Aircraft deicing plans developed by carriers must be approved by the FAA and are reviewed and

revised annually to ensure they incorporate any new information, practices, or procedures. Many

carriers have developed their own aircraft deicing plans because this approach allows them more

flexibility. 

The FAA provides guidance to Part 121 carriers on developing an acceptable

deicing plan in Advisory Circular 120-60, “Ground Deicing and Anti-icing Program.” Aircraft
Section 13.0 - Relationship to Other Regulations

13-22

deicing plans include: (1) a management plan describing operational responsibilities and

communication procedures; (2) a description of the aircraft deicing and anti-icing methods used

by the carrier; (3) flight and ground crew training procedures including annual reviews and

testing; (4) procedures for preflight contamination checks; and (5) holdover tables for estimating

snow and ice protection provided by ADFs and procedures for using the tables. Holdover tables

included in a deicing plan must be approved by the FAA and must be used whenever deicing

and/or anti-icing is performed. When takeoff occurs within the holdover time, carrier personnel

are required to conduct a pretakeoff contamination check for frozen contamination within five

minutes of takeoff. The pretakeoff contamination check may be made from inside the aircraft

provided it is performed by trained personnel and takeoff occurs before the holdover time expires. 

If the holdover time is exceeded, carrier personnel must either repeat the aircraft deicing process,

inspect the aircraft from the outside within five minutes of takeoff, or use an alternate FAAapproved procedure (e.g., wing-mounted ice sensors).

13.4.2 FAA Winter Operating Regulations for Airports

FAA regulates only airports that serve air carriers that operate aircraft with seating

capacities of more than 30 passengers. The operations may be either a scheduled or unscheduled

service. FAA regulations applicable to airports are published in Part 139 of the Federal Aviation

Regulations and stipulate that these airports must be certified by the FAA and hold an operating

certificate. For certification purposes, airports are required to compile a manual describing the

airport’s operating procedures, lines of succession for airport operational responsibilities, and the

airport’s facilities and equipment. The manual must be approved by the FAA, implemented by the

airport, and revised when necessary. 

The operating procedures described in the manual must comply with all

operational specifications outlined in Subpart D of Part 139. Specifically, Section 313 of Subpart

D includes provisions for a snow and ice control plan for airports located in regions where snow

and icing conditions regularly occur. The snow plan must include: (1) operational requirements

and procedures for the removal of snow, ice, and slush from runways, taxiways, and aircraft
Section 13.0 - Relationship to Other Regulations

13-23

parking ramps; (2) a description of the priorities assigned to individual taxiways and runways; (3)

names of personnel responsible for implementation of the snow plan and their areas of

responsibility; (4) the location of a snow removal coordination center (usually referred to as a

snow control center); (5) a list of materials used for snow and ice control and procedures for their

application; and (6) procedures for the prompt notification of all aircraft operators using the

airport when any portion of the runways or taxiways is not safe for the operation of aircraft. 

The FAA allows airports to use chemicals and mechanical methods, such as

brooms and snow plows, to keep airfield pavements free of snow and ice. Chemicals used for

deicing/anti-icing airfield pavements may be liquids (e.g., potassium acetate or glycol-based fluids)

or solids (e.g., airside urea (also called carbamide), calcium magnesium acetate (CMA), sodium

formate, and sodium acetate). The FAA requires that airports use only products that meet or

exceed SAE specifications. SAE standards for liquid pavement deicers/anti-icers are provided in

SAE AMS 1435, while those for solid pavement deicers/anti-icers are provided in SAE AMS

1431A. Airports may also use airside urea meeting the U.S. military specifications provided in

MIL SPEC DOD-U-10866D. Vendors of chemical pavement deicers/anti-icers are required to

provide the airport with a Material Safety Data Sheet and certification that their product conforms

to SAE or U.S. military specifications. Granular materials, such as sand, may be used to improve

aircraft braking. 

Although there are currently no regulations concerning aircraft deicing with which

airports must comply, the FAA recommends in their Advisory Circular 150/5200-30A, “Airport

Winter Safety and Operations,” that airports develop local aircraft deicing plans. The plan should

include the locations of designated aircraft deicing areas, communication procedures, and traffic

flow strategies. The FAA also recommends that airports establish a committee responsible for

aircraft deicing issues. The committee members should include representatives from airport

management, airline operations staff, fixed-base operators, air traffic control personnel, and other

interested parties such as corporate tenants or the military. FAA recommends that the committee

meet prior to the beginning of the deicing season to discuss and review the following issues: (1)

Part 121 carrier aircraft deicing programs and their effects on airport operations; (2) ground flow
Section 13.0 - Relationship to Other Regulations

13-24

strategies to shorten taxiing routes and minimize holdover time for deiced aircraft; (3) takeoff

clearances and departure slot allocation procedures; (4) locations for aircraft deicing/anti-icing,

including locations for secondary deicing/anti-icing; (5) communication procedures between air

traffic control and aircraft waiting to be deiced/anti-iced; and (6) airport collection practices for

containment of wastewater generated during aircraft deicing/anti-icing activities, including the

responsibilities of individual tenants.

13.5 Society of Automotive Engineers (SAE) Standards for Aircraft Deicing/AntiIcing Operations

SAE is a professional organization dedicated to improving safety and promoting

new technologies in all sectors of the transportation industry through the development of

engineering standards. The SAE Aerospace Council is responsible for developing standards for

the aircraft industry and is organized into technical committees, each with its own area of

specialization. The committee responsible for aircraft deicing and anti-icing issues is the G-12

Committee. 

13.5.1 SAE G-12 Committee

The G-12 Committee is a voluntary consensus body responsible for developing

standards, material specifications, and recommended practices for all aspects of aircraft deicing

and anti-icing. The following subcommittees perform the work of the G-12 Committee:

C Fluids Subcommittee;

C Deicing Facilities Subcommittee;

C Holdover Time Subcommittee;

C Training Subcommittee;

C Ice Detection Subcommittee;

C Methods Subcommittee;

C Future Deicing Technology Subcommittee; and 

C Aircraft Ground Deicing Equipment Subcommittee.
Section 13.0 - Relationship to Other Regulations

13-25

Members serve on the G-12 Committee and its subcommittees on a voluntary

basis. Members include representatives from the airlines, the FAA, Transport Canada, fixed-base

operators (FBOs), airports, fluid manufacturers, equipment manufacturers, airframe

manufacturers, and the Airline Pilots Association. 

The standards developed by the G-12 Committee are published in a series of 

documents. SAE standards for aircraft deicing fluids (i.e., Type I fluids) are published in

Aerospace Material Specification (AMS) 1424B, while those for aircraft anti-icing fluids (i.e.,

Types II, III, and IV) are published in AMS 1428C. SAE-recommended practices for the storage,

transfer, and application of aircraft deicing and anti-icing fluids are published in Aerospace

Recommended Practice (ARP) 4737C. This document also includes SAE-approved holdover

tables for use with Type I, II, and IV fluids. SAE specifications for aircraft deicing vehicles are

published in ARP 1971 for large-capacity trucks and ARP 4047 for small-capacity trucks. SAE

ARP 4902 contains design standards and recommended operation practices for aircraft deicing

facilities. Standards for airfield pavement deicing/anti-icing agents can be found in AMS 1435 for

liquids and AMS 1431B for solids. Glycol-based airfield pavement deicers/anti-icers must

conform to standards contained in AMS 1426C.

The G-12 Committee meets several times each year to review and revise these

documents and often participates in joint meetings with the International Organization for

Standardization (ISO), SAE’s European counterpart. The SAE/ISO joint meetings provide a

forum to exchange technical information and promote international cooperation for the

development of uniform standards in Europe and North America.

13.5.2 SAE Standards and Certification for Aircraft Deicing/Anti-icing Fluids

SAE does not dictate the composition of ADFs, but requires that they contain a

freezing point depressant and any additives that enable the fluid to meet SAE performance-based

standards. To receive SAE certification, fluid formulators are required to submit a sample of the

fluid to an independent laboratory for testing. The tests are conducted by the Scientific Material
Section 13.0 - Relationship to Other Regulations

13-26

International (SMI) laboratory in Miami and the Anti-Icing Materials Laboratory (AMIL) of the

University of Quebec in Chicoutimi, Canada. The tests are designed to measure the physical

properties, material compatibility, aerodynamic performance, anti-icing performance, and stability

of the fluid. Physical properties measured include the flash point, specific gravity, pH, refractive

index, freezing point, surface tension, and viscosity. SAE material compatibility tests include tests

designed to measure the fluid’s effect on aircraft parts, including metals, transparent plastics, and

painted surfaces. Aerodynamic performance tests are used to ensure that the fluids flow off 

aircraft surfaces during take-off. Anti-icing performance tests measure the fluid’s ability to

prevent ice formation on test plates exposed to freezing conditions. Fluid stability tests are used

to measure thermal and storage stability, and the effect of hard water and shearing on fluid

performance. The fluid sample submitted must be representative of the fluid offered

commercially. A new sample must be submitted for testing whenever changes in ingredients or

manufacturing processes are made.

Although SAE standards do not specify which freezing point depressants should be

used in aircraft deicing/anti-icing fluid formulations, all such fluids currently used in the U.S.

contain propylene glycol or ethylene glycol as the freezing point depressant. Since industry

specialists believe that glycol has the potential to cause fires in some aircraft electrical systems,

SAE requires glycol-based fluids to contain a fire suppressant. Although SAE does not specify

which fire suppressant should be used, fluid formulators state there are only two effective fire

suppressants currently available for this application, tolyltriazoles and benzotriazoles, both of

which are considered to be toxic to aquatic organisms (see Sections 9.2.1.3 and 9.2.2). 

13.5.3 SAE Environmental Information Requirements

In addition to meeting performance-based specifications, formulators are required

by SAE to provide the following environmental data for their fluids: (1) BOD; (2) total oxygen

demand (TOD) or COD; (3) biodegradability; (4) aquatic toxicity; and (5) trace contaminants. To

comply with SAE standards, BOD tests should be performed at an incubation temperature of

20 C for a period of 5, 15, 20 or 28 days. The TOD or COD for the fluid should be reported in o
Section 13.0 - Relationship to Other Regulations

13-27

kilograms of oxygen per kilogram of fluid, while biodegradability should be reported as the ratio

of BOD and TOD (or COD). 

Aquatic toxicity data should be reported as an LC50 concentration in units of

milligrams per liter. SAE requires the aquatic toxicity tests to be performed in accordance with

EPA (40 CFR 797.1300 and 797.1400, revised July 1, 1989) or OECD (Organization for

Economic Cooperation and Development Guidelines for Testing of Chemicals, Methods 202 and

203) protocols. SAE does not specify which species should be used for the toxicity tests, but

requires formulators to use species that have been selected by regulatory agencies for inclusion in

discharge permits. 

SAE also requires fluid formulators to report the presence of trace contaminants of

sulfur, halogens, phosphate, nitrate, and heavy metals (lead, chromium, cadmium, and mercury). 

Fluid formulators must report the concentration of trace contaminants either as percentage weight

or parts per million, and indicate the analysis method used and the detection limits.

Because SAE does not specify the concentration of the fluid to be tested, airlines

and FBOs are often unable to directly compare the environmental data provided by different

formulators. To remedy this situation, the Air Transport Association (ATA), a trade association

representing the principal U.S. passenger and air cargo carriers, asked SAE during the May 1999

meeting to consider incorporating standardized environmental testing and reporting protocols into

the SAE fluid specifications for both aircraft and pavement deicing/anti-icing agents. Specifically,

ATA recommended that SAE: (1) require that aquatic toxicity tests be performed in accordance

with the EPA method for whole effluent toxicity (WET) tests using fluid concentrate as the test

sample; (2) specify the test species to be used for WET tests; (3) require that toxicity data be

reported in a standardized manner for the fluid concentrate and 50/50 mixture; (4) specify a

standard BOD test (e.g., 5-day BOD at 20 C); (5) establish a May 1 reporting date requiring that o

formulators provide toxicity data for new and reformulated fluids or certification that their fluids

have not changed; and (5) consider setting toxicity standards for aircraft deicing/anti-icing fluids

using the toxicity of current formulations as the baseline. ATA believes these changes, if adopted
Section 13.0 - Relationship to Other Regulations

13-28

by SAE, will enable fluid purchasers to compare the environmental impact of competing fluid

formulations and encourage formulators to develop fluids with lower aquatic toxicity. In

response, the Fluids Subcommittee created an Environmental Workgroup, comprising

representatives from SAE and ATA, which will review the current SAE requirements and assess

ATA’s recommendations.

13.6 References

1. 61 Federal Register 19542 - 19544 (DCN T10568).

2. U.S. Department of Health and Human Services. Toxicological Profile for

Ethylene Glycol and Propylene Glycol. September 1997 (DCN T11084).

3. Meeting Summary for Albany Aircraft Deicing Summit. March 1999 (DCN

T10542).

4. Portland International Airport, Portland, OR. NPDES Permit (DCN T11049).

5. Environmental Canada. Scientific Considerations in the Development of a Revised

CEPA Glycol Guideline Value. November 1996 (DCN T10376).

6. Environment Canada/Transport Canada. Canadian Water Quality Guidelines for

Glycols - An Ecotoxicological Review of Glycols and Associated Aircraft AntiIcing and Deicing Fluids. May 1999 (DCN T11079).
13-29

Table 13-1

Airport Permit Data for ADF-Contaminated Wastewater 

Airport Permit Monitored otherwise noted) Frequency

Type of Parameters Effluent Limitation (mg/L unless

Cleveland POTW COD 1,500 and 12,500 lbs/day Once/week

Hopkins NH -N 72 and 600 lbs/day Once/week

International Flow 700 gpm and 1 MGD Once/month

(CLE) TSS Monitor Once/week

3

pH Monitor Once/month

Tri-State NPDES pH, TSS, O&G, Monitor Once/year for all parameters

(Huntington, Storm Water TOC, BOD ,

HTS) (General) TKN, COD,

5

Nitrate-Nitrite,

Total P

Des Moines NPDES Outfall A Outfall B

International Storm Water

(DSM) (Individual) 

BOD5 Twice/week

NH3-N Twice/week

EG Twice/week

pH Twice/week

DO Twice/week

BETX Once/month

O&G Once/month

Monthly Daily Monthly Daily

Avg. Max. Avg. Max.

100 150 100 150

1.0 1.6 37 55

125 190 125 190

6 - 9 6 - 9

> 1.0 > 1.0

Monitor Monitor

Monitor Monitor

POTW pH 5.0 - 10.5 Once/week

Flow 150,000 gpd Continuously

COD 10,000 lbs/day Daily or as necessary to

control discharge

Duluth NPDES BOD , COD, NPDES permit does not require Sampling schedule varies

International Storm Water TSS, N, TKN, monitoring; however, it is considered yearly

(DLH) NH -N, P, EG, a BMP.

5

3

PG, DEG, O&G,

pH

Anchorage NPDES BOD COD, Monitor Once/year (during spring

International Storm Water TSS, O&G, EG, snow melt) for all parameters

(ANC) (General) PG, urea,

5, 

potassium,

acetate, NH -N, 3

pH, flow
Table 13-1 (Cont.) Section 13.0 - Relationship to Other Regulations

Airport Permit Monitored otherwise noted) Frequency

Type of Parameters Effluent Limitation (mg/L unless

13-30

Seattle-Tacoma NPDES TPH, TSS, Monitor Eight times/year for all

International Storm Water Turbidity, Fecal parameters

(SEA) (Individual) coliform, BOD ,5

EG, PG, Cu, Pb,

Zn, LC50

NPDES Flow 4,800 gpm Once/day

Industrial pH 6 - 9 Once/week

(Interim) O&G 8 (monthly avg.); 15 (daily max.) Once/week

TSS 21 (monthly avg.); 33 (daily max.) Once/week

BOD5 Monitor Once/month

Total glycols Monitor Once/month

TPH Monitor Once/month

Fecal coliform Monitor Once/month

VOAs Monitor Once/year

Semivoas Monitor Once/year

Cu Monitor Once/year

Pb Monitor Once/year

Zn Monitor Once/year

LC Monitor Once/year (based on previous 50

results)

Billings Logan NPDES pH, O&G, Monitor Monitoring waived until 2000

International Storm Water BOD , COD,

(BIL) (Individual) TSS, total glycol

5

Newark NPDES Flow Monitor Once/month

International Industrial pH 6 - 9 Once/month

(EWR) (Expecting TPH 15 Once/month

storm water COD 100 Once/month

permit TSS 100 Once/month

approval)

Logan NPDES O&G 15 Three times/month

International Storm Water TSS 10 Three times/month

(BOS) (Interim) pH 5 - 7 Three times/month

General Mitchell NPDES DO, BOD , Monitor Four times/year for all

International Storm Water COD, TSS, parameters

(MKE) (General) O&G, pH, TKN,

5

NH -N, 3

Total P, 

Total Glycol,

Cu, Pb, Zn, Flow
Table 13-1 (Cont.) Section 13.0 - Relationship to Other Regulations

Airport Permit Monitored otherwise noted) Frequency

Type of Parameters Effluent Limitation (mg/L unless

13-31

Buffalo Niagara POTW Flow 27,000 gallons/day Once/month for all

International EG + PG 10,000 lbs/day parameters

(BUF) BOD5 250

O&G 100

pH 5 - 12

TSS 250

VOA Monitor

Semivolatile Monitor

organics

NPDES Flow Monitor Once/month

Storm Water O&G 15 (daily max) Once/month

pH 6 - 9 Once/month

TKN Monitor Once/month

NH3-N 2.4 (daily avg.); 16 (daily max.) Once/month

BOD5 30 (daily avg.) Once/month

EG 500 (daily max.) Once/month

Surfactants Monitor Once/month

Benzene Monitor Four times/year

Toluene Monitor Four times/year

Bradley POTW Max. daily flow 288,000 gpd Weekly for all parameters

International Max. flow rate 200 gpm during discharge to POTW

(BDL) Flow per batch 20,000 gal

PG 125

TSS 125

BOD5 200

COD 600

pH 5.5 - 10

Salt Lake City Storm Water Apr.-Sept. Oct.-Mar.

International Industrial Flow Monitor Monitor Once/month

(SLC) O&G 10 daily max. 10 daily max. Once/month

BOD Monitor 25(a)/35(b) Twice/yr. (Oct-Mr once/yr.) 5

COD Monitor Monitor Twice/yr. (Oct-Mr once/yr.)

Nitrate-Nitrite Monitor Monitor Twice/yr. (Oct-Mr once/yr.)

pH Monitor Monitor Once/month

EG N/A 70 Once/month

PG N/A 70 Once/month

Greater Rockford NPDES BOD , pH, TSS, Monitor Unknown

(RFD) Storm Water N

5 

Airborne Air Park NPDES COD, TSS, pH, Monitor Four times/month for all

(ABX) Storm Water NH -N, DO, paramters (in winter)

(Individual) TDS, O&G Once/month for all

3

parameters (in summer)
Table 13-1 (Cont.) Section 13.0 - Relationship to Other Regulations

Airport Permit Monitored otherwise noted) Frequency

Type of Parameters Effluent Limitation (mg/L unless

13-32

Denver POTW Flow Monitor Continuously

International

(DIA) BOD 9 tons/day (daily max.); 7 tons/day Once/hour

(monthly avg)

As 0.33 Unspecified but

Cd 3.4 representative of discharge

Cr 3.6

Cu 6.1

Pb 2.2

Hg, 0.13

Mo 0.71

Ni 5.6

Se 0.66

Ag 2.9

PERC 1.5

Zn 15.6

NPDES Dry

Storm Water Dry Weather/ Wet Weather Weather/

General Wet Weather Summer Summer

COD Monitor Monitor Once/day Monitoring

O&G Monitor Monitor Once/mo. is required

pH Monitor Monitor Once/mo. whenever

TSS Monitor N/A Once/mo. the DIA

PG Monitor Monitor Once/mo. staff,

EG Monitor N/A Four times/yr. during the

BOD Monitor N/A Four times/yr. inspection

TPH Monitor Monitor Four times/yr. of outfalls,

Total P Monitor N/A Four times/yr. observes or

Nitrate-Nitrite Monitor N/A Four times/yr. suspects an

TKN Monitor N/A Four times/yr. illicit

Flow Monitor N/A Four times/yr. discharge.

Chloride Monitor N/A Four times/yr.

DO Monitor if COD N/A Once/week

> 75

Albany POTW BOD 240 Once/day for all parameters

International TSS 25

Airport (ALB) COD Monitor

5

Total glycols Monitor

NPDES BOD 500 lbs/acre (land applied) Once/month for all

Storm Water Benzene 0.008 parameters (except PG)

General o-xylene 0.005

5

m+p-xylene 0.01

Toluene 0.005

Lead 0.05

PG 1 Once/day during deicing

season
Table 13-1 (Cont.) Section 13.0 - Relationship to Other Regulations

Airport Permit Monitored otherwise noted) Frequency

Type of Parameters Effluent Limitation (mg/L unless

13-33

Minneapolis-St. NPDES CBOD 900 tons/year Once/day

Paul International Storm Water

(MSP) (Interim)

5

pH 6 - 9 Once/day

Flow, TSS, NH - Monitor Once/day for all parameters 3

N,

O&G, TKN, Monitor Three times/week for all

Total P, DO parameters

COD, EG, PG, Monitor Once/week for all parameters

BETX

NPDES Total Phenols, Monitor Four times/year

Storm Water As, Cd, Cr, Cu,

(Interim) Pb, Hg, Ni, Si,

Zn, Cn

Kansas City NPDES pH 6 - 9 Once/month

International Storm Water EG Monitor Once/year

(MCI) Flow Monitor Once/month

TPH 10 (monthly avg.); 15 (daily max.) Once/month

BOD5 30 (monthly avg.); 45 (daily max.) Once/month

COD 90 (monthly avg.); 120 (daily max.) Once/month

TSS 50 (monthly avg.); 100 (daily max.) Once/month

O&G 10 (monthly avg.); 15 (daily max.) Once/month

POTW Flow 75 gpm Once/day

BOD5 400 lbs/day Once/day

Chicago O’Hare POTW BOD Monitor Every 6 million gallons

TSS Monitor discharged

(ORD) Flow Monitor

5

International 

NPDES Outfall A Outfall B

Storm Water Flow Monitor Monitor Once/month

pH Monitor Monitor Once/month

BOD5 10 20 20 40 Once/month

NH3-N

 April-Oct. 1.5 3.0 1.5 3.0 Once/month

 Nov.-March 3.6 7.2 3.6 7.2 Once/month

O&G 15 30 Once/month

TDS 1,000 1,000 Once/month

Monthly Daily Monthly Daily

Avg. Max. Avg. Max.
Table 13-1 (Cont.) Section 13.0 - Relationship to Other Regulations

Airport Permit Monitored otherwise noted) Frequency

Type of Parameters Effluent Limitation (mg/L unless

13-34

Portland NPDES During and one day following

International Storm Water deicing events between Nov.

Airport (PDX) 1 and Apr. 30

Outfall A Outfall B Outfall A Outfall B

Flow Monitor Monitor Once/hour Once/hour

COD Monitor Monitor Once/3 hours Once/3hrs

BOD Monitor Monitor Once/6 hours Once/6hrs 5

DO Monitor Monitor Once/6 hours Once/day

Bioassay Monitor N/A Twice/year N/A

Methanol N/A Monitor N/A Once/day

Ethanol N/A Monitor N/A Once/day

Propanol N/A Monitor N/A Once/day

Baltimore/ POTW pH 6 - 10 During each batch discharge

Washington BOD 7,000 lbs/day from 600,000 gallon storage

International TSS 300 mg/L tank

(BWI) Phosphorus 12 mg/L

5

TPH 100 mg/L

Flow Monitor

Cadmium 0.21 mg/L Once/year

Chromium 6.89 mg/L

Copper 6.59 mg/L

Lead 6.81 mg/L

Nickel 2.82 mg/L

Zinc 17.85 mg/L

Key: (a) Monthly average.

(b) 7-day average.

As - Arsenic NH3-N - Ammonia as nitrogen

BOD - 5-day Biochemical Oxygen Demand Ni - Nickel 5

BETX - benzene, ethylbenzene, toluene, and xylene O&G - Oil and grease

Cd - Cadmium P - Phosphorus

COD - Chemical oxygen demand PERC - Tetrachoroethylene

Cu - Copper PG - Propylene glycol

DEG - Diethylene glycol TDS - Total dissolved solids

DO - Dissolved oxygen TKN - Total kjedahl nitrogen

EG - Ethylene glycol TPH - Total petroleum hydrocarbons

Hg - Mercury TSS - Total suspended solids

LC - Lethal concentration where 50% of test VOA - Volatile organics 50

organisms die Zn - Zinc

Mo - Molybdenum

N/A - Not applicable

N - Nitrogen
Section 13.0 - Relationship to Other Regulations

13-35

Table 13-2

Summary of Available Permit Data

Parameters Frequently Range of NPDES Range of POTW

Monitored Limitations Limitations Range of Sampling Frequency

Chemical Oxygen Demand 90-120 mg/L 600-1,500 mg/L 1/day - 1/year

(COD) 400-12,500 lbs/day

Ammonia 1-55 mg/L 72 mg/L 1/day - 1/year

600 lbs/day

pH 5 - 9 5 - 12 1/day - 1/ year

Total Suspended Solids 10-100 mg/L 25-300 mg/L 1/day - 1/year

(TSS)

Oil and Grease (O&G) 8-30 mg/L 100 mg/L 3/week - 1/year

5-day Biochemical Oxygen 10-150 mg/L 200-250 mg/L 1/hour - 1/year

Demand (BOD5) 7-9 tons/day 7,000 lbs/day

900 tons/year

Ethylene Glycol 70-500 mg/L NA 2/week - 1/year

Propylene Glycol 1 mg/L 10-125 mg/L 1/day - 1/year

Total Glycols NA 10,000 lbs/day 1/day - 4/year

Copper NA 6.1 - 6.59 mg/L 4/year - 1/year

Lead NA 0.05-6.81 mg/L 1/month - 1/year

Zinc NA 15.6 - 17.85 mg/L 4/year - 1/year

NA - Not available.
Section 14.0 - Economic Profile

14-1

14.0 ECONOMIC PROFILE

This section presents a profile of significant economic and financial aspects of the

air transportation industry as it relates to airport deicing operations. The demand for airport

deicing operations is a derived demand; that is, deicing operations are performed solely to provide

the service of transporting passengers and cargo by air. Thus, the economic conditions underlying

airport deicing operations are those of the air transportation industry itself. This profile examines

airports in Section 14.1, and airlines in Section 14.2. All tables appear at the end of this section.

14.1 Airports

Section 14.1 is divided into four major sections. Section 14.1.1 discusses Federal

Aviation Administration (FAA) airport classification and the number of airports, their sizes, and

their locations. Section 14.1.2 presents an overview of airport financial management, while

Section 14.1.3 describes ownership and management patterns among airports. Finally, Section

14.1.4 discusses issues concerning airport capital financing.

14.1.1 Determining the Number, Sizes, and Locations of Airports

A number of classification systems are used to describe airport size and

significance; Section 14.1.1.1 discusses the most important classification systems, and profiles the

distribution of airports by level of activity. Section 14.1.1.2 then relates airport activity and

snowfall, both likely determinants in the probability of an airport potentially performing significant

deicing operations, to the profile developed in Section 4.1.1.1.

14.1.1.1 FAA Airport Size Classifications

The primary source of data on the locations and sizes of U.S. airports is the FAA’s

Air Carrier Activity Information System (ACAIS) databank. ACAIS contains revenue passenger

enplanement and all-cargo data. The database supports the FAA’s Airport Improvement Program
Section 14.0 - Economic Profile

14-2

(AIP) entitlement activities. AIP funding is largely based on airport activity as determined by

annual passenger boardings (by FAA definition, boardings include only revenue-earning

customers on aircraft engaged in air commerce), although other criteria apply as well. The

ACAIS database contains data for all airports reporting any passenger boarding activity (1).

Another data source is the FAA’s congressionally mandated National Plan of

Integrated Airport Systems (NPIAS). The NPIAS database identifies 3,344 existing airports that

are significant to national air transportation and, therefore, eligible to receive grants under the

AIP. Activity and geographical location largely determine inclusion in the NPIAS (2). NPIAS

airports account for virtually all commercial airline activity and approximately 92% of general

aviation (GA) with complete geographic coverage of the U.S. (3). Although there is some

overlap in the airports included in both the ACAIS and NPIAS databases, the NPIAS includes a

total of 3,344 existing airports, while the calender year (CY) 1997 ACAIS database contains

1,715 airports.

EPA may find other airport classification systems more suited to its purposes

should it choose to undertake an effluent guideline. However, in this report, EPA utilizes the

FAA airport definitions because they are frequently used in the industry. The FAA defines

airports in the ACAIS database according to passenger boardings. The FAA’s definition of

revenue passenger boardings is broad and includes enplanements for activities such as sightseeing

flights. Although these activities are generally not large, at certain airports (e.g., Grand Canyon,

AZ, Juneau, AK), they can form a significant share of aircraft boardings. Below are the

descriptions of the different airport classifications.

The first distinction lies between commercial service airports and noncommercial

service airports. Commercial service airports are defined as airports with both scheduled

passenger service and a minimum of 2,500 revenue passenger boardings on aircraft engaged in air
Section 14.0 - Economic Profile

 Boardings at private airports or airports without scheduled commercial service are included in the ACAIS. For 1

example, in CY 1996, Orlando Sanford boarded almost 280,000 passengers (ranked 144 in passenger service); because

these were unscheduled commercial flights, Sanford could not be designated a nonhub primary airport. Sanford’s

boardings were, however, included in total U.S. boardings used to determine the hub status of other airports (1).

14-3

commerce per year. Commercial service airports cannot be privately owned. The number of 1

commercial service airports declined from 568 in 1988 to 529 in 1997, a decrease of roughly 7

percent (3, 4). 

Commercial service airports are further subdivided into primary airports, those

commercial service airports with more than 10,000 enplanements per year, and nonprimary

commercial service airports having between 2,500 and 10,000 annual enplanements. The number

of commercial service airports classified as primary airports increased from 396 in 1988 to 417 in

1997. Thus, while the total number of commercial service airports fell between 1988 and 1997,

the percentage of airports rated as “primary” increased from 70% of commercial service airports

in 1988 to 79% in 1997 (3, 4).

Primary commercial service airports are further classified as hubs (large, medium,

small and nonhubs). The designation of hub depends on the percentage of total passenger

boardings occurring at that airport, and again, is used primarily for distributing AIP funds. 

Because definitions of airport size are determined by annual enplanements, the number of hubs

and the designation of airports can change from year to year. For example, in CY 1993, FAA

classified 65 airports as large and medium hubs. Washington Dulles International was ranked

twenty-eighth, Tampa International twenty-ninth, and Baltimore-Washington International thirtyfirst in passenger boardings; all were medium hubs (5). In CY 1996, there were 71 large and

medium hubs; Baltimore-Washington International was ranked twenty-eighth and Tampa

International was ranked twenty-ninth in passenger boardings, but both were large hubs while

Washington Dulles International was ranked thirty-first, and was still a medium hub. 

Airlines also individually designate airports as hubs; these designations should not

be confused with FAA hub designations. An airline will define an airport as a hub if that airport is
Section 14.0 - Economic Profile

 FAA defines passenger enplanements as the number of revenue passenger boardings on aircraft engaged in air 2

commerce at airports that receive scheduled passenger service.

 Gross landed weight of cargo refers to the rated maximum gross landing weight of each cargo-only aircraft type (i.e., 3

the maximum allowable weight of the plane and its potential cargo), and does not measure the actual weight of the cargo

carried in those planes.

 This includes airports such as Rickenbacker Airport in Columbus, OH, which reported zero boardings in 1997, but 4

landed over 725 million pounds of cargo-only aircraft. Rickenbacker acts as an operational hub for Federal Express,

and therefore operates large jet aircraft in poor weather conditions.

14-4

used to facilitate connections between airline routes; airline hubs may also be large or small. Los

Angeles International, for example, is a large hub by FAA definition, but a nonhub by airline

definition because it is not used by any major airline to facilitate connecting service. Conversely,

Cleveland Hopkins International is a large hub for Continental Airlines, because it facilitates

connections for Continental’s route structure, but is a medium hub by FAA definition. Unless

otherwise noted, EPA uses FAA’s definition of hub throughout this section.

Table 14-1 presents total passenger boardings and the number of airports by FAA

definition for CY 1997. This table emphasizes the dominance of large hubs (those with more than

1% of total U.S. enplanements) in the air transportation network. The 30 large hubs in CY 1997 2

(5.7% of commercial service airports) accounted for 68.6% of the 640.7 million total U.S.

passenger boardings. As a group, large hub airports averaged over four times as many annual

boardings as medium hubs (3.3 million average annual boardings), and 21 times as many

boardings as small hubs (660,000 average annual boardings). Large and medium hubs combined

accounted for almost 90% of total U.S. passenger boardings in 1997.

FAA also tracks data on cargo-only service at airports. Statistics are published for

those airports where the total annual weight of arriving cargo-only aircraft is at least 100 million

pounds. In 1997, 106 airports “qualified” as having significant cargo-only service; activity at 3

qualifying cargo-only airports is also included in Table 14-1. Although qualifying airports

generally correspond to large, medium, and small FAA hubs (e.g., 66% of large, medium and

small hubs are also qualifying cargo-only airports), two nonprimary commercial service and four

noncommercial service airports have a significant amount of cargo-only service.4
Section 14.0 - Economic Profile

 GA airports excluded from the NPIAS include more than: 1,000 publicly owned-public use landing strips, 1,200 5

privately owned-public use landing strips, and 12,000 privately owned- private use landing strips.

14-5

Although insufficient data are available to determine this statistically, there may be

a trend towards the development of specialized airports with significant cargo service but

relatively little passenger service. Airports that fit this pattern tend to be near large cities (e.g.,

Hulman Regional – Indianapolis, IN; Pease International – Boston, MA; Rickenbacker

International – Columbus, OH; Greater Rockford – Chicago, IL; Willow Run – Detroit, MI). 

Much of the traffic at these airports is express package delivery that is time-sensitive. By utilizing

smaller airports, the cargo service airlines avoid the delays common at large passenger airports,

yet these smaller airports are convenient to major business sources. Also, from the airports’ point

of view, investment in cargo service infrastructure may be less costly than passenger service. 

Less information is available about GA airports. Some GA airports may have

scheduled commercial service, but because they have less than 2,500 annual enplanements, they

are not ranked as commercial airports. The 1997 ACAIS database contains some information on

1,186 noncommercial service airports; however, the most current NPIAS contains data on 2,806

GA and reliever airports, and indicates that the U.S. has an additional 15,000 GA airports

currently in existence (6).5

GA airports are subdivided into reliever airports (334 in 1998), and other GA

airports. Airports are designated as relievers if they maintain a certain level of operations per year

(50 based aircraft, 25,000 itinerant, or 35,000 local operations per year) or FAA has determined

its location desirable for instrument training, and if they are located in a metropolitan statistical

area with a population of 250,000. In essence, relievers reduce congestion at major airports in the

area by providing an alternate airport for GA aircraft to operate from. Business/executive jets

frequently operate out of relievers, and they may be more likely to fly in bad weather than other

GA aircraft. Large cargo-only jet aircraft may also use relievers; for example, some qualifying

cargo-only airports, such as Rickenbacker, OH and Willow Run, MI are relievers. Nonreliever

GA airports are probably a relatively insignificant source of aircraft deicing fluid runoff due to the
Section 14.0 - Economic Profile

14-6

level of activity at the airport and the types of aircraft flown at the airport; most GA aircraft

apparently do not fly in weather poor enough to require any significant deicing. 

Table 14-2 uses ACAIS data from 1993-1997 to track growth in overall air traffic

and growth by airport definition. First, commercial service airports account for roughly 99% of

all passenger boardings, based on the small difference between figures for total passenger

boardings and total passenger enplanements. Overall, both enplanements and boardings grew at

an average annual rate of 5.3 percent. Total enplanements at large hubs grew more quickly than

total enplanements (an average annual rate of 7.2 percent). Some of this growth is due to 

increasing the average size of large hub airports, and some due to the increasing number of large

hub airports; the average number of enplanements at large hub airports grew at a more moderate

3.9% per year. Nonprimary commercial service airports grew most slowly, both in terms of total

enplanements (average annual growth rate of -6%) and average enplanements per airport (average

annual growth rate of 0.2 percent). 

14.1.1.2 Airports with Potentially Significant Deicing/Anti-Icing Operations

EPA has determined that aircraft operations are likely to be a better predictor of

the level of deicing activity than enplanements. The FAA supplied EPA with aircraft operations

data by airport; Table 14-3 characterizes airports by non-GA flight operations and FAA airport

hub status. GA activities were excluded from the operations classification because GA aircraft

either do not fly in weather requiring deicing, or require minimal use of aircraft deicing/anti-icing

fluids (ADFs). While large hubs account for almost 70% of passenger enplanement activity (see

Table 14-1), they account for less than 50% of non-GA aircraft operations. This reflects the

larger size of aircraft operating from large hubs, a result of the large demand for passenger service

to those hubs. Also, operations cannot be neatly correlated with hub status and enplanement

activity. Within each hub definition, some airports have more operations than airports in the next

higher hub grouping (e.g., the largest medium hub had over 311,000 non-GA operations, while

the smallest large hub had 210,000 non-GA operations).
Section 14.0 - Economic Profile

14-7

EPA cross-classified airports by operations data and snowfall data to estimate the

number of airports with the potential for significant deicing/anti-icing operations. For the

purposes of this study, EPA selected a benchmark of 10,000 operations per year (excluding

general aviation) to represent significant operations, and excluded airports with less than 10,000

annual operations from further analyses. EPA did not include general aviation in its operation

measurement because the Agency believes that most GA aircraft do not operate during deicing

conditions. Also for the purposes of this study, EPA assumed that mean annual snowfall

(including ice pellets and sleet) of less than 1 inch would not result in significant deicing

operations; therefore, EPA excluded airports in regions with annual snowfall of less than 1 inch

from further analyses. A total of 212 airports met the criteria for operations and average snowfall

(see Section 4.3.1.1 for details concerning the criteria to determine these airports). 

EPA divided operations data into five subcategories (7):

C Category A: 425,000 # operations < 850,000 per year

C Category B: 210,000 # operations < 425,000 per year

C Category C: 100,000 # operations < 210,000 per year

C Category D: 50,000 # operations < 100,000 per year

C Category E: 10,000 # operations < 50,000 per year.

EPA divided snowfall data into four subcategories (8):

C Category 1: 60 inches # snowfall < 120 inches per year

C Category 2: 30 inches # snowfall < 60 inches per year

C Category 3: 15 inches # snowfall < 30 inches per year

C Category 4: 1 inch # snowfall < 15 inches per year.
Section 14.0 - Economic Profile

14-8

Table 14-4 presents airports with the potential for significant deicing/anti-icing

operations classified by operations, snowfall, and FAA size definition. Of the 212 airports that

meet the operations and snowfall criteria, data for only 211 of these airports are contained in the

ACAIS database. Therefore, Tables 14-4 and 14-5 are based on the 211 airports that meet both

of EPA’s criteria and are also in the ACAIS database. 

Table 14-4 is organized so that the uppermost left cell contains the largest airports

by operations classification and the largest average annual snowfall, while the lowermost right cell

(excluding the subtotal row and column) contains the smallest airports with the least average

annual snowfall. The classification by hub status is included because of the importance of large

and medium hubs in the U.S. air transportation system. For example, based on the averages

presented in Tables 14-1 and 14-2, the single large hub with “A” level operations and a minimum

of 60 inches of snow probably accounts for more operations and passenger enplanements than the

combined operations and enplanements of the 17 nonhub and noncommercial service airports that

also average at least 60 inches of snow. A total of 21 large hubs (of 30 total) and 23 medium

hubs (of 40 total) meet the snowfall and operations criteria.

Table 14-5 compares EPA’s classification system with FAA’s size classification for

the 211 airports contained in both the ACAIS and NPIAS databases. Air carrier operations

decline from 74% of non-GA operations in the highest operations category to 19% in the lowest

operations category. As carriers fly the largest aircraft and are less likely to cancel flights due to

weather, these operations may generate the most ADF use. While airplane operations decrease

dramatically with airport size, carrier enplanements decrease much less dramatically since carriers

use larger aircraft than air taxis. In the highest operations category, carrier enplanements account

for 95% of average enplanements, while in the lowest operations category, they account for 78

percent. Finally, the number of GA operations increases as airport size decreases; in the largest

category, GA operations are a fraction of non-GA operations (less than 8%), while at the smallest

airports, GA operations are 264% of non-GA operations.
Section 14.0 - Economic Profile

14-9

14.1.1.3 Analytic Issues and Evaluation of Data Availability

ACAIS data (enplanements and gross landed weight of cargo) are made available

to the public approximately one year after the CY for which they are collected (e.g., the FAA

finished compiling ACAIS data for CY 1997 by the end of October 1998, and reports based on

that data were available on the Internet in December 1998). Components of the ACAIS database

have also recently been made available in electronic format (Excel spreadsheet) at the FAA web

site. Operations data are not currently available at the FAA web site and must be requested

directly from the FAA. The FAA can provide data in electronic format to other government

agencies if requested to do so, and in greater detail than is posted on the Internet (1). 

The primary issues for airport activity data are data consistency and coverage. 

Databases used for this industry profile were generated by the FAA for its own internal purposes;

therefore, not all databases contain data for all airports. For example, the 1997 ACAIS

enplanement database contains data for 1,715 airports, while the operations database contains

data for 449. Data for almost 1,300 airports in the enplanements database are not in the

operations database while 31 airports in the operations database are not in the enplanements

database. Furthermore, the number of airports with data in the enplanements database ranges

from 1,703 to 1,909 between 1993 and 1997. It is not apparent why these inconsistencies exist. 

Presumably, a single request to the FAA for all necessary data will result in a single database

containing all relevant information. If such a database cannot be obtained, care will be required

not to overlook airports with potentially significant deicing/anti-icing operations not contained in

the operations database. For example, by using regression analysis on available operations,

enplanement and cargo-only service, EPA identified a handful of airports having a high probability

of more than 10,000 non-GA operations per year that were not contained in the operations

database. Such an analysis may be necessary to ensure that no airports are overlooked.
Section 14.0 - Economic Profile

 Except in specific legal agreements signed prior to the 1982 law prohibiting such practices. Therefore, a few airport 6

owners, such as the Port Authority of New York, still legally use airport revenues to subsidize nonairport activities. 

Periodic questions of “revenue diversion” do arise, the most notorious being the claim by the City of Los Angeles that it

14-10

14.1.2 Airport Financial Management and Accounting

Section 14.1.2.1 presents an overview of the major features of airport financial

management, followed by a discussion of data availability for airport financial analysis in Section

14.1.2.2 with a profile of airport finances based on the limited information that is available. 

Finally, Section 14.1.2.3 presents issues identified during the analysis of airport financial data,

including the ability of an airport to pass costs through to airlines. 

14.1.2.1 Overview

Airport financial management is fundamentally different from most other business

enterprises, because many airports (including most large commercial airports) have traditionally

used a residual-cost approach to finances. Under this approach, the airlines as a group assume

the financial risk of running the airport by agreeing to pay any costs of running the airport not

paid by other nonairline users. Under the alternative compensatory approach, the airport assumes

the financial risk; airlines pay rates set equal to their estimated cost of using the facility. Using the

compensatory approach, there is no guarantee the airport will cover costs; however, the airport

can keep any surplus of revenues over cost and accumulate capital for future development. Many

airports may combine the two approaches (9). 

Airport financial statements are difficult to compare between airports and with

other businesses due to differences in the size and objective of different airports, the type of

airport ownership (e.g., private or public), financial approaches to operations, and legal

restrictions on airport finances. For example, because most airports use a residual-cost approach,

they receive sufficient revenues from airlines to pay the cost of capital investment and are unlikely

to account for depreciation on assets the way most businesses do. Also, airports are legally

prevented from using their revenues for nonairport purposes. Therefore, airport financial 6
Section 14.0 - Economic Profile

was owed almost $90 million by the Los Angeles Department of Airports for alleged unreimbursed capital and operating

expenses relating to the sale of airport property (11).

14-11

statements do not meet the standards of Generally Accepted Accounting Principals (GAAP), and

an airport’s revenue surplus or loss is not equivalent to profit or loss (10). 

Typical airport operating statements include the following categories (9):

C Operating revenues and operating expenditures on key “cost centers”: 

-- Airfield area (e.g., runways, taxiways, aprons),

-- Terminal area concessions (e.g., food and beverage services, travel

services such as car rentals, specialty shops, personal services,

amusements, advertising, outside concessions such as terminal

parking, ground transportation, hotels),

-- Airline leased areas (e.g., ground equipment rentals, offices, ticket

counters, cargo terminals, hangers, operations and maintenance

areas),

-- Other leased areas (e.g., fixed-based operators (FBOs), freight

forwarders, government offices, businesses in airport industrial

parks, equipment and cargo Terminals rented by nonairline users),

and

-- other operating revenues and expenditures.

C Nonoperating revenues (e.g., grants-in-aid (AIP), interest on investments,

subsidies by government, leasing of properties not related to operations);

C General and administrative expenses (e.g., expenses of overhead services:

accounting, legal, planning, public relations); at some airports (such as

small municipal airports), these expenses, including policing and firefighting

expenses, may appear in the governing authority’s budget, not the airport

budget;

C Nonoperating expenses (e.g., interest on outstanding debt, contributions to

government); and

C Depreciation.

Under a residual-cost approach, the airport determines costs and revenues from each general

operational area above, and airlines’ fees are set by the anticipated revenue shortfall. Any surplus

is returned to airlines in the form of lower fees the following year; any loss would be made up in
Section 14.0 - Economic Profile

 Wells (9) claims that airports such as Los Angeles and Honolulu have approached “negative” landing fees in recent 7

years due to overall operating surpluses. 

14-12

higher fees the following year. Both terminal and landing fees, or landing fees only, may be

adjusted by the airport .

7

The compensatory approach may determine fees according to the actual cost of

running the airport, or by market value. The latter is especially common for terminal concessions. 

A growing trend has been for airports to use a mix of the residual-cost and compensatory

approaches. For example, an airport may operate terminal concessions using a compensatory

approach that permits the airport to keep surpluses from concession rents and fees, while it runs

air-side operations using the residual-cost approach.

The financial and operational relationship between airlines and airport is defined in

the airport-use agreement. This document specifies how the risks and responsibilities of running

the airport will be shared, how rates for using facilities and services are calculated, and how

frequently these rates and fees may be adjusted. 

One consequence of the residual-cost approach is that tenants at such airports tend

to have very long-term leases (20 to 30 years) to assure the airport of revenue to finance capital

expenditures. In this case, airlines typically have a majority-in-interest clause in the airport-use

agreement. This clause gives airlines that represent most traffic at the airport the right to review

and veto or defer any capital projects that would significantly increase the fees they pay. Airports

using a compensatory approach to finance are not legally required to allow airlines to review

capital improvement projects, but most do.

The post-deregulation trend in airport financial management has been towards (9):

C Shorter-term contracts of 5 years or less to new tenants or renewal of

existing leases when they expire to permit greater flexibility in adjusting

pricing, investment policy, and space allocation.
Section 14.0 - Economic Profile

 In addition, EPA could not ensure the consistency or accuracy of the data contained in the survey. 8

14-13

C Greater use of the compensatory approach instead of the residual-cost

approach with modification or elimination of majority-in-interest clauses.

C Maximization of revenues through more frequent adjustment of fees,

competitive bidding for concessionaires’ contracts, and greater emphasis

on marketing and developing properties (e.g., airport industrial parks). 

Perhaps the most important new source of revenues at large airports is the

collection of passenger facility charges (PFCs).

In the rapidly changing environment of the air transportation industry since deregulation and the

burgeoning growth of air travel, airports seem more confident of their ability to be financially selfsustaining without residual-cost agreements by more aggressively pursuing all forms of revenues. 

For example, revenues from concession operations at hub airports (of all sizes) may account for

one-third of total airport revenues; at some airports, concession revenues exceed airline revenues

(9). On the other hand, deregulation has made airport finances somewhat more risky because

airlines can reduce or discontinue service to an airport with little warning.

14.1.2.2 Airport Financial Data

Consistent data on airport financial conditions are not readily available. One

source of data on airport operating revenues is the American Association of Airport Executives’

(AAAE) Survey of Airport Rates and Charges, 1997-1998 (12). Because of the way this survey

was administered, EPA cannot draw statistically reliable inferences from the survey results. 

However, more than 50% of large, medium, and small hubs (by FAA definition) responded to the

survey, as well as over 220 nonhub and GA airports. Tables 14-6 and 14-7 summarize the results

of this survey. Because the survey was voluntary, not all respondents answered all questions;

EPA summarized the data for only those airports that provided complete operating revenue and

expense data.8

Table 14-6 indicates the type of operating agreements used by responding airports. 

Although residual-cost agreements have historically been the most common type of operating
Section 14.0 - Economic Profile

 For the large, medium, and small hubs as a group that responded to the AAAE survey, parking fees comprised almost 9

41% of parking and concession revenues, exceeding airline landing fees as a source of revenue.

 The FAA utilized AAAE data from 1992 to characterize capital expenditures in its most recent NPIAS (6). As noted 10

below, the FAA recently started systematically collecting airport financial statements. This information is not publicly

available in electronic format suitable for data analysis, and airport expenses are not characterized by cost center (e.g.,

airside, terminals), but by cost type (e.g., labor, utilities, insurance).

14-14

agreement, the number of airports currently using compensatory or hybrid residualcost/compensatory agreements exceeds the number of residual-cost agreement airports in all

airport categories except medium hubs.

Table 14-7 summarizes operating revenues by major source, operating expenses,

and government subsidies, by FAA airport definition. Average operating revenues for large hubs

are five times those of the next largest airport type – medium hubs – while average large hub

enplanements are approximately three times the average medium hub enplanements (see Table 14-

1). Airline and air cargo revenues as a percentage of operating revenues diminish with airport

size, while FBO and GA revenues as a percentage of operating revenues are inversely related to

airport size. Parking and concessions are extremely important sources of airport operating

revenues for all except GA airports. Finally, operating expenses exceed operating revenues for 9

GA airports, making them more reliant on government subsidies than any other class of airport. 

The AAAE survey provides data on overall operating expenses, but not the source

of those expenses. Nor does the AAAE survey provide information on capital expenditures. EPA

used its airport mini-questionnaires to focus on these issues. Nine airports were sent miniquestionnaires; in addition, one airport voluntarily responded. Because of the small sample size,

these results cannot be considered statistically significant; however, it is the only current source of

information on expenses available to EPA. To minimize burden to the respondent, airports were 10

allowed to use “best professional judgement,” and therefore all answers should be considered

approximate (13).

Table 14-8 characterizes airport expenditures by three key cost centers (airfield,

terminal, and hanger areas), general and administrative (G&A) costs, debt service, and
Section 14.0 - Economic Profile

 Airport #1 is a new airport, which may account for some of the apparent anomalies in its responses. For example, 11

new facilities presumably require less maintenance, hence the low expenditures on the airfield and terminals relative to

other airports, but may have relatively high debt to pay for them. 

 These financial statements are available at http://www.faa.gov/arp/arphome; choose “Browse by Topic” from the 12

menu and select “Financial Reports.” Each year’s reports are contained in a single PDF file that can be searched by the

airport’s location ID. Further detail is available for the “other” category, but only in hard copy at the FAA (10). 

14-15

depreciation; enplanement and operations data are also included to indicate relative airport size. 

With the exception of Airport #1, airfield operating and maintenance accounts for a range of 13%

to 32% of all airport expenditure. For large and medium hubs terminal expenditures are higher 11

than airfield expenditures. This is presumably due to the passenger service at large and medium

hubs. With one notable exception, larger airports are willing to incur more debt than smaller

airports. 

14.1.2.3 Analytic Issues and Evaluation of Data Availability

Little systematic analysis has apparently been done on airport finances. The

AAAE Survey of Rates and Charges contains the largest readily available source of airport

financial data. However, the AAAE Survey does not provide sufficient data for economic and

financial impact analysis. First, coverage is incomplete. Second, because of the way the survey

was administered, statistical estimates based on the responses are not reliable. Third, the

responses do not deal with airport operating expenses or capital expenditures. AAAE has

apparently performed some survey work of capital expenditures. The data cited by the FAA in

the NPIAS are dated (1992).

Commercial service airports have recently been legally required to submit annual

financial statements to the FAA. These financial statements are available for 1996 and 1997 on

the Internet; in addition, the FAA will make an electronic version of these statements available to

other federal agencies. These financial statements are the best source of publicly available 12

information to systematically analyze and summarize (e.g., for the industry profile) airport

financial information. However, there are a few drawbacks to using this data source. It does not

contain non-commercial service airports, and therefore does not include airports such as
Section 14.0 - Economic Profile

14-16

Rickenbacker, OH or Willow Run, MI that may have significant cargo-only operations. While

these files contain detailed information on airport revenue sources, airport expense information is

much less detailed, and probably not adequate for economic and financial impact modeling. 

Finally, because airports are not required to submit audited data, and because different airports

may use different accounting bases (e.g., cash vs. accrual) for their reports, these summary

financial statements may not be directly comparable between airports (14). 

Airport to Airline Cost Pass-Through

A significant question concerning airport finances also cannot be answered by the

information provided in the FAA files: what percentage of cost increases are typically passed

through to airlines in the form of higher fees? At residual-cost airports, the airlines are legally

responsible to cover the costs of the airport; this suggests that airports pass 100% of costs

through to airlines. Airline representatives have stated that costs on airports, FBOs, and the FAA

are all passed through to the airlines. Furthermore, according to the industry, landing fees – the

most likely vehicle for passing through airport costs – are a significant factor in determining the

level of airline service provided to cities; an increase in landing fees can cause an airline to reduce

or halt service to the airport (15). 

Landing fees account for roughly 2% to 3% of overall airline operating costs (9). 

ATA comments that although landing fees are a relatively small percentage of airline operating

costs, airport costs, including landing fees, are one of the most rapidly rising components of costs. 

According to ATA, any cost component is of great concern to the industry if it is increasing,

regardless of the level of the cost (15). Furthermore, many airline operating costs are difficult for

airlines to directly control in the short run. For example, jet fuel prices are determined by market

forces. Similarly, labor costs are generally determined through multiyear union contracts. 

Airlines therefore have incentive to control any component of operating cost over which they

have leverage, including landing fees (16). Although landing fees comprise a relatively small

percentage of overall operating costs, a substantial increase in landing fees can significantly affect

airline operating costs. If, for example, Boston’s Logan Airport increased its landing fees by
Section 14.0 - Economic Profile

14-17

$0.50 per 1,000 pounds (a 22% increase), the landing fees paid by U.S. Airways, Logan’s most

frequent user, would increase by approximately $1.6 million per year (12, 17, 18).

The small sample of airports visited or surveyed by EPA provide mixed evidence

on the issue of cost pass-through. Five of 10 respondents to the EPA airport minisurvey indicated

that they would anticipate passing through to commercial air carriers at least 90% of any cost

increase caused by improving wastewater treatment systems. One airport indicated that 100% of

such costs would be passed through on a special assessment to commercial carriers, and two

other airports anticipated other fee increases that would significantly impact commercial carriers. 

A ninth airport stated that it would pass through 100% of these costs, but would not specify on

whom it would raise fees. One of these nine airports indicated that although it was likely to pass

through 100% of hypothetical compliance costs to airlines, in practice its ability to do so may be

limited by fixed escalator clauses in its airport-use agreements (13). 

However, airports do not uniformly believe that all costs can be passed through to

commercial air carriers. Of the airports EPA visited, Chicago O’Hare expressed a strong

preference for increasing revenues through concessions and other sources rather than increasing

landing fees (16). Nearby General Mitchell International stated that the proximity of Chicago

O’Hare places makes it difficult to increase revenues through increased landing fees; if General

Mitchell increases its landing fees, it risks losing a significant portion of its passenger service to

Chicago O’Hare (19). Airports that use a compensatory approach to financial management may

consult airlines before undertaking capital improvements, even though they are not required to

and the airline is not legally responsible for project costs. Salt Lake City International, for

example, negotiated an increase in landing fees of $0.01 per 1,000 pounds with airlines that offset

the costs of recycling aircraft deicing fluid; a $0.01 increase in landing fees increased the cost of

landing a Boeing 747F by less than $7.00 (20). Finally, the tenth surveyed airport indicated it

would not pass through any proposed wastewater treatment costs. 

Perhaps the most important long-run determinant of the financial health of an

airport is the demand to visit the city or region served by the airport. If the airport is a “terminal,”
Section 14.0 - Economic Profile

14-18

people are going to that city. If an airport is a “hub,” people are only going there to get

somewhere else. Thus, terminal (“origin-destination demand”) airports fare better than airline

operational hub-and-spoke (“connecting demand”) airports in the bond market. Passenger

enplanements are an indicator of demand for service to an airport (and therefore revenues). If an

airline using an airport as an operational hub pulls out at short notice (which it can since

deregulation), passenger enplanements will probably drop significantly. In such cases, airports

may risk significant losses in revenues and financial stability by increasing landing fees. Smaller

airports face the same problem; if the costs of serving the airport rise too much, the airport risks

losing its airline service. Thus, cost pass-through may vary according to the specific

circumstances of individual airports.

14.1.3 Airport Ownership and Management

Section 14.1.3.1 presents an overview of major patterns of airport ownership and

management, followed by a discussion of data availability and analytical issues in Section 14.1.3.2.

14.1.3.1 Overview

Different types of airport ownership affect decision-making at the airport, and the

airport’s access to funds for financing capital improvements. Typical ownership structures

include:

C Municipal/county government: airport is owned by city/county and run as a

department of that entity and managed by that entity’s board of directors

(e.g., city council); sometimes there may be a separate airport commission

or advisory board. Policy decisions are made in the context of the wider

city plan and the airport has no independent authority to issue bonds (9).

C Multipurpose port authority: legally chartered institutions operating a

variety of publicly owned facilities such as airports, harbors, toll roads, and

bridges. The authority typically has considerable decision-making

autonomy from city/state government including the authority to issue debt

in the form of revenue bonds (9).
Section 14.0 - Economic Profile

14-19

C Single-purpose airport authority: similar to a port authority but only runs

airport (or airports); like a port authority, it can issue debt, but typically has

a narrower revenue base to operate from (9).

C State-operated airports: typically run by the state’s Department of

Transportation that can issue general obligation or revenue bonds. The

state may also raise revenues through aviation fuel taxes. Only a handful of

large-/medium-sized commercial airports are run by states: Alaska,

Connecticut, Hawaii, Maryland, Rhode Island. The federal government

owns one airport: Pomona Airport, Atlantic City, NJ (9).

C Private ownership: privately owned and operated, these airports are

typically, but not exclusively, small GA airports (9); ABX, for example, is

privately owned and operated by Airborne Express, which uses it as their

operational cargo hub.

The recent trend for airports is to use independent authorities. Airports often

outgrow political jurisdictions and impact surrounding communities both negatively and

positively. Independent authorities allow the airport to spread the tax burden to other

communities that benefit from that airport. (Note that government subsidies are much more

important for smaller airports, especially as a percentage of operating costs; no large hubs, for

example, are subsidized – see Table 14-7). Such authorities also allow smaller, more specialized,

on-the-scene decision-making organizations somewhat insulated from politics. In addition to

delegating management to an independent authority, that authority may further delegate airport

management to a private contractor (21).

Table 14-9 summarizes ownership patterns found among airports responding to

the AAAE Survey of Rates and Charges. The majority of respondents are municipally owned, a

pattern that holds for all airport hub classes. Furthermore, “multigovernment” airports are

typically airports with joint ownership by multiple municipalities. Thus, airport ownership by

cities is dominant among AAAE survey respondents.
Section 14.0 - Economic Profile

14-20

14.1.3.2 Analytic Issues and Evaluation of Data Availability

Two issues arise out of differences in airport ownership. The first is related to

financial accounting. A municipal airport run by a department of the municipal government may

account for costs in a significantly different way than other airports. Specifically, many costs of

the airport such as accounting, legal, public relations, even policing and firefighting may be

attributed to other city departments, not the airport. Thus, its financial position may be more

difficult to analyze than an airport run by an independent authority.

The second issue is based on the lack of information available concerning privately

owned airports. They are not required to submit financial summary statements to the FAA. Also,

private ownership may affect airport access to funds for capital improvement; a significant portion

of capital for publicly owned airports is raised through the municipal bond market. However,

most, but not all, privately owned airports are relatively small GA airports (3) and are unlikely to

perform many deicing operations. 

14.1.4 Financing Capital Improvements

Section 14.1.4.1 profiles major sources of capital funding for airports and their

relative importance in the system. Section 14.1.4.2 discusses data availability and analytic issues

concerning airport capital financing.

14.1.4.1 Overview

In general, airports rely on the following sources of funds to finance capital

improvements:

C Federal funding through the FAA AIP: funding comes from the Airport and

Airway Trust Fund with revenues raised from taxes on airfares and

airfreight waybills, surcharges on international flights originating in U.S.,

taxes on aviation gas and jet fuel, and registration fees on aircraft. Almost
Section 14.0 - Economic Profile

 The FAA has proposed raising the maximum PFC charge. While endorsed by airports, this measure is opposed by 13

airlines on the grounds that: (1) it helps most those airports that least need help (i.e., large airports with large levels of

enplanements), (2) because projects funded with PFCs do not have to meet airline approval, they believe many

unnecessary projects are funded, and (3) PFCs increase the cost of air travel and therefore decrease the quantity of air

travel demanded (24, 15). Airports argue that incumbent airlines frequently oppose airport expansion in order to restrict

airline competition (25). 

14-21

50% of AIP funds are “apportioned” to airports by formula for use on any

project meeting the guidelines for AIP-funded projects. The remaining

funds are distributed at the FAA’s discretion for specifically approved

projects. Most AIP funding goes for runways, taxiways, aprons, runway

lighting and navigational aids; it may be used for building deicing pads and

purchasing snow removal equipment (22). AIP funding may not be used to

build hangers, parking facilities, or most terminal development (3). All

NPIAS airports are eligible for AIP funds (2). AIP grants accounted for

20% of airport capital expenditures in 1996 (23).

C FAA-authorized Passenger Facility Charges (PFCs): the FAA authorizes

commercial airports to impose PFCs for funding certain types of capital

improvements similar to those eligible for AIP funds. Airports may charge

$1, $2, or $3 per enplaned passenger and passengers may be charged PFCs

no more than twice on each leg of a round-trip journey. Airports must 13

notify airlines of intention to charge the PFC and present to them its capital

plan and financing strategy. Large and medium-sized hubs that use PFCs

must give up AIP funds ($0.50 of AIP funds for every $1.00 of PFCs

collected up to a maximum of 50% of their AIP apportionment); half of the

relinquished AIP funds go into a discretionary fund earmarked for small

airports (22). PFCs accounted for 16% of 1996 airport capital funding

(23).

C State funding: this varies widely by state; Alaska and Hawaii provide

considerable assistance while other states (e.g., New Hampshire) provide

minimal assistance. Funding comes from state fuel taxes, aircraft, airport,

and pilot registration fees, and general funds. State funding accounted for

4% of airport capital expenditure in 1996 (23).

C Bond market: although some city and states may fund airport expansion

with general obligation bonds, or self-liquidating general obligation bonds,

more typically airports use tax-exempt general revenue bonds. Typically

airport revenue bonds have 25 to 30 year terms. Tax-exempt bonds are by

far the single most important source of airport capital, accounting for 58%

of 1996 funding (23).
Section 14.0 - Economic Profile

14-22

C Airport revenues: capital improvements funded directly from airport

revenue streams, whether airside or landside. Airport revenues accounted

for 2% of capital funding in 1996 (23).

In addition:

C Airport may lease airport-owned land to a private individual or company

who finances improvements (e.g., airlines that build their own terminal on

airport property out of airline funds (9)).

Table 14-10 characterizes airport capital expenditure, and the sources of funding

for that capital expenditure, for recipients of EPA’s airport minisurvey. Small and nonhub capital

expenditure is significantly smaller than large and medium hubs. Furthermore, while capital

spending at small and nonhubs is primarily funded through AIP grants and PFCs, a large

percentage of large and medium hub capital expenditures is financed through bonds. With one

exception, all airports surveyed charge the maximum PFC ($3 per passenger), and that single

exception has applied for permission to charge PFCs starting in the year 2000. Finally, most of

these airports do not have a majority-in-interest clause in the airport-use agreement; a majority-ininterest clause requires airline approval of capital improvement projects.

An FAA study released in 1996 evaluated the airport access to funding for capital

improvements and the effectiveness of the AIP program (26). Some key points of this evaluation

are:

C From 1985 through 1995, AIP funded 14% capital spending at large

commercial airports, 28% at medium-sized commercial airports, and 41%

at small airports (including relievers and GA). 

C PFCs are generating roughly $1 billion per year, 50% of which is

concentrated at the 10 largest enplaning airports. PFCs are an important

source of revenue for funding bond issues. Airports may be obligating the

revenue stream from PFCs 10 to 15 years into the future (15).

C Airports tend to perform at least as well as any other borrowers in the

municipal bond market. Of the 995 airport bond issued between 1985 and
Section 14.0 - Economic Profile

14-23

1995, all but one were rated “investment grade” (48% of large airport bond

issues and over 65% of medium and small airport bond issues by volume

were rated AAA). The airport industry has never defaulted on a bond

issue.

C The tax exempt status of municipal bonds saves airports approximately 2%

in interest costs (estimated at $1 billion per year).

The report concluded:

“The nation’s commercial airports today do not face systemic or widespread

obstacles to finding willing investors, financing debt-service reserve funds,

obtaining bond insurance and other debt guarantees, and generally exercising

leveraging strategies that foster airport development.”

Although the report found no systemic problems: 

“At large and medium-sized airports, where major airlines exert significant

influence over the scope and timing of investment, near-term financial realities

facing airline management can create divergent airport-airline perspectives on the

appropriate timing and scope of capital improvements due to their immediate

implications for landing fees and other airline costs. . . . At small airports there is

evidence of financial barriers to the desired level of development of terminal and

land-side facilities.” 

These financial barriers were deemed to be caused by insufficient revenues to cover bond issues or

a lack of state or local aid.

While a General Accounting Office (GAO) analysis of airport capital funding

generally concurred with FAA’s conclusions, it was not as confident as FAA about the overall

availability of capital funding for airports (23). GAO projected a $4 billion per year shortfall of

capital funds for airport improvements, although this conclusion must be qualified because the $4

billion figure was based on planned capital expenditure and was not prioritized by need. GAO

noted that on a percentage basis, the shortfall was more significant for small airports rather than

large and medium hubs. GAO also found that small airports are most dependent on government

funding for capital projects.
Section 14.0 - Economic Profile

14-24

14.1.4.2 Analytic Issues and Evaluation of Data Availability

The issue of capital availability will be important if EPA decides to proceed with

development of an effluent guideline regulation for airport deicing operations. Due to the size of

airports, and the level of construction necessary to withstand heavy usage, airside capital projects

are potentially quite expensive, and the availability of capital funding could be of concern. FAA

airport financial statements provide substantial data for characterizing sources of capital funding

of the industry. However, the problem of local financial barriers to raising capital may become an

important component of any impact analysis necessary to develop an effluent guideline. 

In addition, airports, especially smaller airports, tend to rely heavily of government

funds, such as AIP grants, to pay for capital improvements. The availability of AIP and PFC

funds for use in meeting an effluent guideline may be difficult to determine. AIP funding is

determined each year and Congress generally limits distribution of AIP funds to a lower level than

authorized (26). Discretionary AIP funds are granted for specific projects only. Although PFCs

may be a more predictable long-run source of revenues for capital improvements, airports may be

“earmarking” projects to be funded by PFCs well into the future (15). Also, note that PFC funds

provide little capital for airports with relatively small enplanements. 

Should EPA move forward with a deicing effluent guidelines regulation, it is

unlikely that airports could reasonably anticipate financing much capital expenditure to meet those

regulations through AIP or PFC sources. This is due to both the limited availability of AIP funds

and the tendency for AIP and PFC funds to be earmarked for specific projects. Combined with

the perceived shortfall of capital funds for airport improvements, airports might only be able to

meet such a regulation by postponing other capital projects. Thus, availability of capital may be a

crucial issue in analyzing potential impacts of an effluent guideline regulation on airport deicing

operations.
Section 14.0 - Economic Profile

14-25

14.2 Airlines

Civil aviation can be divided into two groups: air carriers, and GA. Air carriers are

defined as a company or other organization that carries passengers or cargo for hire or

compensation by air; GA constitutes all other civil aviation (27). 

Aircraft utilized by air carriers are distinguished from GA aircraft by the size,

frequency and intensity of use. Table 14-11 displays some comparisons between selected types of

GA and air carrier aircraft. Although there exist 21 times as many fixed-wing GA aircraft as air

carrier aircraft, 75% of GA aircraft are single-engine piston aircraft, and each GA aircraft

operates less than one-fifth as many hours per year as the average air carrier aircraft. Although

the number of GA twin-engine turbojets outnumbers air carrier twin-engine turbojets, the latter

are typically much larger (i.e., Boeing 737s and Douglas DC-9s/McDonnell Douglas MD-80s and

MD-90s, carrying a minimum of 100 passengers). GA twin-engine turbojets tend to be much

smaller aircrafts such as Learjets, carrying less than 20 passengers, flying as corporate/executive

aircraft. Because GA aircraft are unlikely to fly in weather bad enough to require deicing – or if

they do deice, they are likely to need relatively small quantities of deicing fluids – the remainder of

this section will focus on air carriers.

14.2.1 Types of Air Carriers

Section 14.2.1.1 presents an overview of U.S. air carriers, major definitions, and a

profile based on traffic statistics. Section 14.2.2.2 discusses data availability.

14.2.1.1 Overview

Air carriers can be divided into separate categories using two classification

systems. The first classification system is primarily based on aircraft size. Air carriers must, in

general, obtain a “fitness” certificate (covering economic and financial criteria) from the U.S.

Department of Transportation (DOT) and an “operating” certificate (covering safety, training and
Section 14.0 - Economic Profile

Part 121 operating certificates are required for aircraft carrying more than nine passengers, more than 7,500 pounds 14

payload, or for turbojet aircraft regardless of passenger capacity. Part 135 operating certificates are required for aircraft

carrying nine or fewer passengers, or less than 7,500 pounds payload. Prior to 1996, Part 135 certificates were required

for aircraft carrying 30 or fewer passengers.

 For EPA’s purposes, small certificated and commuter airlines are essentially identical. They offer the same type of 15

service and operate the same type of aircraft. Small certificated air carriers are basically commuter airlines that chose to

get certificated rather than registered because: (1) certificated airlines have a better chance of obtaining lucrative mail

contracts in Alaska than do registered air carriers, or (2) bankruptcy laws – no longer in effect – made it easier for banks

to recover capital from bankrupt certificated carriers compared to registered carriers (28).

14-26

other operating issues) from the FAA. Aircraft size is a primary determinant of the type of

certificate airlines require from each agency. Air carriers may be classified as (28):

C Large certificated carriers: fly aircraft capable of carrying a minimum of 61

passengers, or payload capacity of 18,000 pounds, or conduct international

operations. Large certificated carriers require a Section 401 fitness

certificate from DOT, and a Part 121 operating certificate from FAA.

C Small certificated carriers: fly aircraft that carry less than 61 passengers,

have a payload capacity of less than 18,000 pounds, and do not conduct

international operations. Small certificated carriers also require a Section

401 fitness certificate from DOT, and a Part 121 or a Part 135 operating

certificate from the FAA.14

C Commuter carriers: defined as air taxis that have a published service

schedule of at least five round trips per week between at least two places. 

Commuters register with DOT under Section 298, but do not require a

fitness certificate. They also need a Part 121 or a Part 135 operating

certificate from the FAA.15

One significant factor about the definitions above is that DOT reporting requirements vary

according to the above definitions. Large certificated carriers must report monthly traffic

statistics and quarterly financial statistics to DOT’s Bureau of Transportation Statistics (BTS);

these statistics are regularly published. Small certificated carriers and commuters report

scheduled service only on a quarterly basis, and, although they do report financial statistics, those

are not published due to a confidentiality agreement.

Large certificated air carriers are also characterized by annual revenues. Airline

classification by revenues include (29):
Section 14.0 - Economic Profile

14-27

C Major airlines: annual revenues greater than $1 billion;

C National airlines: annual revenues greater than $100 million, but less than

$1 billion;

C Large regional airlines: annual revenues greater than $20 million, but less

than $100 million; and

C Medium regional airlines: annual revenues greater than zero, but less than

$20 million.

Although DOT does not report small certificated/commuter airline data according to revenue

classification, some private publications might.

National and regional airlines tend to focus their service in particular regions of the

country – a market “niche” strategy where the niche is defined by the geographic region served. 

Major airlines generally provide nationwide and often worldwide service. The primary difference

between national and regional large certificated carriers is the scale of service as indicated by the

level of revenues earned. Small certificated carriers/commuter airlines generally follow the same

regional marketing strategy, and are distinguished from large certificated regionals more by the

size of the aircraft flown than the type of service provided (30). Appendix D presents a list, by

revenue classification, of EPA’s estimate of U.S. airlines in operation as of June 1998, along with

their key financial and traffic statistics, where available.

National and regional airlines often provide “feeder” services to major airlines by

carrying passengers from smaller airports not served by major airlines to the major airlines’

operational hubs. Through “code-sharing” agreements, the regional airlines can schedule such

feeder flights under the major airline’s scheduling code. The flight appears to be a “through”

flight rather than a “connecting” flight, thus gaining a higher ranking in travel agents’ computer

reservation systems and therefore having a greater probability of being booked (30). The major

airline gains by appearing to schedule service to more cities, while the regional airline gains by

having its service appear to the traveler as being provided by a major airline. Through code-
Section 14.0 - Economic Profile

14-28

sharing agreements and non-code-shared feeder flights, major airlines and national/regional

airlines often have more of a complementary relationship rather than a competitive relationship.

Table 14-12 presents summary traffic statistics by carrier type. A revenue

passenger-mile (RPM) is defined as one revenue passenger transported one mile in revenue

service and is a commonly used measure of the quantity of passenger service provided; an airline

transporting one passenger 1,000 miles provides more service than an airline transporting one

passenger 500 miles. Available seat-miles (ASM) is a commonly used measure of airline capacity:

the number of seats available for revenue service multiplied by the number of miles those seats are

flown. Load factor is a measure of the proportion of capacity actually used in revenue service,

and is derived by dividing revenue passenger miles by available seat-miles (31). 

As is the case for airports, the airline industry is dominated by a handful of very

large entities. Thirteen major airlines (three of which provide only cargo service) account for

83% of passenger enplanements and 88% of cargo ton-miles. Flying larger aircraft over longer

distances, as indicated by passengers per aircraft-mile and miles per passenger, major airlines

account for over 90% of RPMs and ASMs.

14.2.1.2 Data Availability

BTS tracks a wide range of traffic and activity statistics on airlines at the level of

the business entity (32). The BTS Green Book is published monthly and contains traffic statistics

for all large certificated carriers. These data include key measures of airline capacity and capacity

utilization, such as available seat-miles, revenue passenger-miles, passenger enplanements,

passenger and cargo ton miles, aircraft departures and hours flown. Data are provided for both

scheduled and unscheduled service, for each airline’s entire route system, and domestic and

international routes separately. Comparisons are provided between the latest month, the same

month in the previous year, the latest 12 months in aggregate, and the previous 12 months.
Section 14.0 - Economic Profile

14-29

The BTS Blue Book tracks activity for small certificated and commuter airlines

(31). The Blue Book is published quarterly, and only scheduled service statistics are presented. 

Basic measures of airline capacity and capacity utilization, such as available seat-miles, revenue

passenger-miles, passenger enplanements, passenger and cargo ton miles, aircraft departures and

hours flown, are included; however, less detail is provided than in the Green Book. Comparisons

are provided between the latest quarter, the same quarter in the previous year, the latest 12

months in aggregate, and the previous 12 months. 

To determine airline service to individual airports, BTS also publishes Airport

Activity Statistics for each calender year (18). BTS provides passenger, freight, mail, and cargo

(cargo equals the sum of freight and mail) enplaned at each airport by each large certificated

carrier. BTS also publishes scheduled and unscheduled aircraft departures for each airline at

individual airports by aircraft type. BTS does not publish the destinations of passenger and cargo

enplanements or aircraft departures, nor does it publish data for small certificated/commuter

airlines, intrastate traffic, or foreign airlines. 

14.2.2 Air Carrier Finances

Section 14.2.2.1 profiles the air transportation industry based on financial

characteristics. Section 14.2.2.2 summarizes availability of key data necessary for analyzing

airline finances.

14.2.2.1 Overview

Table 14-13 presents air carrier financial statistics by carrier type for the 12-month

period ending June 30, 1998 (29). Major carriers account for over 85% of total air carrier

passenger revenues, operating revenues, and operating expenses, and almost 95% of operating

profit. As a group, only major carriers and small certificated carriers earned positive net income

in this period (operating profits minus tax and interest payments). 
Section 14.0 - Economic Profile

Figures for 1992 include a one-time-only accounting loss due to changes in accounting procedures that affected all 16

industries. However, these losses account for less than 50% of the operating loss for that year; hence, significant losses

were still incurred in 1992 (35).

14-30

Although in the aggregate, approximately 72% of total operating revenues are

earned from passenger service, for specific airlines this average figure is deceptive. Table 14-14

presents 1997 passenger revenues, cargo revenues, and total operating revenues for selected ATA

members. Table 14-14 also includes the number of aircraft owned and full-time-equivalent

employees to provide nonrevenue size comparisons. Airlines are clearly divided among those

providing both passenger and cargo service, but earning the majority of their revenues from

passenger service (a minimum of 82% among the nonrandom sample displayed in this table), and

cargo-only airlines that earn zero revenues from passenger service.

Operating profits presented in Table 14-13 for the airline industry are misleadingly

high in the 12-month period ending in June 1998. Since deregulation in 1978, the airline industry

has been notable for its low profit rate. Between 1978 and 1997, the industry’s average net profit

margin has been -0.1 percent (-1/10 of 1 percent). The record profits earned the last three years

have been well below U.S. industry’s average (15). Roughly 40% of the record profits earned in

the last three years (approximately $2 billion out of 1997 net profits of $5 billion) have been

directly attributable to low interest rates (resulting in significant savings on the cost of purchasing

or leasing jet aircraft) and low jet fuel prices (which account for approximately 10% of industry

operating costs).

Table 14-15 presents scheduled airlines’ operating revenues, expenses, profits, net

profits and profit margin for the period from 1982 to 1997 (33, 34). In only four of the 16 years

did operating profit exceed 5 percent. Moreover, in only one year did the airlines rate of return 16

on investment exceed 12%; a 12% return on investment (pretax) is often considered a benchmark

for the “normal” rate of return – that rate of return necessary to meet the opportunity cost of

capital (35). If the opportunity cost of capital is not met, then in the long run, capital will flow

out of the industry and the industry will contract.
Section 14.0 - Economic Profile

 Some financial problems can be attributed to airlines learning to operate in an entirely new, highly competitive market 17

environment, such as dealings with labor unions in an environment where costs cannot simply be passed on to customers

through regulated fares, the startup of many low-cost airlines (e.g. People’s Express), a wave of mergers (e.g., Frank

Lorenzo and Texas Air), and a shake-out of weaker airlines exposed to competition (e.g., Eastern, Pan Am, (36)).

This view is not shared by all economists; see Shepherd & Brock (37), for example, for a less optimistic view of the 18

degree of airline competitiveness. Also, competition may be restricted on certain routes due to “slot” restrictions at

airports or the dominating presence of a single airline at an airport (“fortress hubs”); this issue is discussed in more

detail in Section 14.2.4.4.

14-31

Although some of the low profit margin in the airline industry can be attributed to

growing pains associated with relatively recent deregulation, the problem of low profits is most

likely systemic in an industry like air transportation. Economists typically measure industry 17

competitiveness by the market share accounted for by the four or eight largest companies (4- or

8-firm concentration ratios) or an index such as the Herfindahl that measures the number of

“effective competitors.” Using such measures, the competitiveness of the airline industry has

declined since deregulation due to mergers. However, air carriers do not really compete at the

national level, but at the route level. As Morrison & Winston pointed out:

“Four effective competitors at the national level can operate in two very different

ways: with each having a monopoly share on one-quarter of the routes or with

each having a one-quarter share on all routes. Although the number of airlines is

the same either way, the second situation is obviously more competitive because

more airlines serve each route. Thus fewer effective competitors at the national

level does not necessarily mean that the industry is less competitive.”

Although lower than its peak in 1985, competition has clearly increased at the route level since

deregulation, leading to a decline in average air fares, and an increase in air travel (35).18

Two features of the airline industry are the key contributors to low profit margins:

low marginal costs on established service, and few barriers to entry. On an already scheduled

flight, the cost of flying one additional passenger is very low (e.g., the cost of flying 121

passengers, instead of 120 passengers, on an already scheduled flight): incremental fuel costs,

food costs, travel agents’ commissions, and similar costs. Because marginal costs are so low, and

because the opportunity cost of flying with empty seats is high (i.e., an empty seat on a flight

represents an opportunity foregone to earn revenue from that seat on that flight), there is a lot of
Section 14.0 - Economic Profile

Crandall argues that in addition to low barriers to entry for existing airlines to enter a market, there are few barriers to 19

entry to the air transportation industry as a whole. New airlines can be started relatively cheaply to compete with

existing airlines (e.g., without having to hire unionized labor, new airlines can start business with a significant cost

advantage over existing airlines because labor costs comprise up to 45% of operating costs). Crandall argues further

that there are barriers to exit: the high cost of leaving the airline industry causes airlines to stay in business even when

they are consistently losing money. Such airlines become some of the most aggressive price cutters in order to generate

any kind of positive cash flow (38).

Robert Crandall, the legendary CEO of American Airlines, has been quoted as saying that one of his proudest 20

achievements at AA was saving the company $50,000 per year by reducing the number of cherry tomatoes in the inflight salads from three to two.

14-32

pressure in the air transportation industry to keep air fares low. Essentially, if an airline can sell a

seat above marginal cost, the airline will earn more net revenue than if it flew with an empty seat,

even if that price does not cover average cost of providing that seat (i.e., total cost of the flight

divided by the number of seats on the flight (38)). 

Low marginal cost is not, by itself, sufficient to keep profits low. If barriers exist

that prevent other airlines from entering a market, the incumbent airline is not necessarily driven

to offer fares as low as marginal cost. However, in many – but not all – airline markets, few

barriers to entry exist; it is relatively easy and inexpensive for existing airlines to switch aircraft

from one route to another. The existence of a second airline, or more, in a market provides the 19

competitive impetus to drive air fares down towards marginal cost (38). Fare wars have been

common in the airline industry since deregulation, often driven by airlines struggling to stay afloat

financially, and willing to fly below average total cost if it will generate some positive cash flow

(i.e., revenues exceed operating costs, but not full costs (36)).

One result of this downward pressure on prices has been that airlines have become

extremely aggressive cost cutters. Airlines are concerned with any cost component exhibiting 20

rapid growth, regardless of the relative size of that cost component (15). Much investment in

new aircraft, for example, is geared towards cost reductions: a Boeing 757 provides 40 more

seats, uses 20% less fuel, and requires a two-person cockpit crew instead of three compared to a

Boeing 727 (15).
Section 14.0 - Economic Profile

 Although the Airline Quarterly Financial Review does contain financial ratios for major carriers not contained in the 21

Yellow Book, the Yellow Book contains data that can be used to calculate important financial ratios.

BTS did indicate that this small certificated/commuter airline income data may be available to other government 22

agencies under certain circumstances (28).

14-33

Table 14-16 presents cost indices and cost components as a percentage of total

operating costs (39). Labor, fuel, and aircraft costs are the three largest cost components,

accounting for over 55% of airline operating costs. Landing fees comprised 2% of operating

costs in 1997. However, note that landing fees did grow 68% between 1985 and 1992 –

approximately 8% per year; this period of rapid growth probably accounts for the attention

airlines have paid to landing fees in recent years.

14.2.2.2 Data Availability

A wealth of financial data is available at the business entity level for large

certificated carriers in the Bureau of Transportation Statistics (BTS) Yellow Book (29). The

Yellow Book is published quarterly and contains detailed income statements and balance sheets for

each large certificated carrier. Income statements are presented system-wide as well as separately

for domestic and international service. Comparisons are provided between the latest quarter, the

same quarter in the previous year, the latest 12 months in aggregate, and the previous 12 months. 

DOT also publishes the Airline Quarterly Financial Review for major airlines (40); however, this

information is available in the Yellow Book and Green Book.

21

BTS does not publish financial data for small certificated/commuter airlines. BTS

does collect income data on passenger service revenues, operating revenues, operating expenses,

and net income for each airline in this category biannually. However, individual airline data are

kept confidential for three years, and only group data are presented in the Yellow Book.

22
Section 14.0 - Economic Profile

 ATA used heating degree days (an engineering index of heating fuel requirements), the number of days with 23

temperatures below 32E F, and inches of snow.

14-34

14.2.3 Airline Deicing Costs

Airlines do not, in general, track deicing costs at the corporate level. In addition,

while deicing costs may be tracked by the airline at individual airports, not all costs are directly

attributed to deicing operations. Thus, for example, labor used for deicing aircraft may not be

tracked as such, as labor may be tracked simply by hours, not by task. Similarly, while a certain

percentage of airport landing fees and other charges are properly attributable to both the direct

operating costs (e.g., vacuum trucks, wastewater treatment operations), and capital costs (e.g.,

deicing pads, drains, retention ponds) of ADF collection and disposal, the exact percentage of

those fees attributable to deicing may be difficult to infer. All deicing costs cited in this section

have been estimated by airlines, some with the assistance of ATA (41).

The methodology used for estimating deicing costs followed the following

procedure. Five major airlines each provided ATA estimates of their deicing costs at a single

airport for the three most recent deicing seasons (October to May of the following year). 

Airports were selected to provide a spectrum of weather and operational conditions. ATA used

these airline specific costs to provide a breakdown of deicing costs into major components. Using

figures on aircraft operations by the airline reporting for a specific airport, and total operations at

that airport during each deicing season, costs were extrapolated from the individual airline to the

entire airport. Finally, each airport’s deicing cost per departure was regressed on three different

measures of weather severity at each airport during the deicing season. By using the same 23

measures of weather conditions, the regression equations were used to estimate the deicing cost

per departure at 236 other airports at which air carriers maintain air service. These costs were

then aggregated using scheduled aircraft departures at each airport to estimate total airline deicing

costs for the three deicing seasons (41).

The largest cost of airline deicing operations is the delays caused to each carrier’s

schedule. Costs of delay measure the direct operational costs of delay to the airlines, but not the
Section 14.0 - Economic Profile

In addition to key operational characteristics, ATA described important features of each airport’s glycol collection 24

system.

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opportunity cost of passengers’ time on the delayed aircraft (42). Labor and operating costs

comprise the second largest component, accounting for 28.5% of deicing costs. The third largest

component of deicing costs is materials, primarily ADF. Finally, capital costs comprise 5.7% of

deicing costs; these only include capital costs incurred by airlines, but not those incurred by

airports. Therefore, ATA believes that the capital costs of deicing operations incurred by airlines

are most likely understated in its study. Furthermore, ATA-member airlines estimate that deicing

costs per aircraft have increased by 20% to 25% over the last five years due to rising ADF prices,

increased use of more expensive anti-icing fluids, regulatory compliance costs, and increased

wages and equipment costs (41).

The importance of the cost of delays to the airline industry can be observed in the

fact that many operational decisions concerning deicing are made on the basis of how they will

impact on-time performance. For example, a carrier’s operational preference for gate/apron

deicing as opposed to central deicing pad deicing, where both types of deicing are available, will

depend on which is less likely to cause delays; it may be more difficult to coordinate activities of

several carriers at a common-use centralized deicing pad without causing delays. Similarly, the

decision by a carrier to provide its own deicing services at an airport as opposed to using another

airline’s or an FBO’s services may hinge on how it will affect on-time performance (41).

Table 14-17 presents the measures of weather severity and deicing costs for the

five airports selected by ATA. Two points are apparent from this table: (1) the wide range of 24

deicing costs per departure at different airports, and (2) the difficulty of easily characterizing

those costs. Excluding Airport C with its semi-desert climate and relatively minimal deicing costs,

deicing costs per departure at the remaining airports range from $84 to $640. With relatively

basic measures of weather severity, costs differ substantially between deicing seasons at one

airport, and between airports. For example, by all three measures of weather, the deicing season

was more severe at Airport E in the 1998-99 season than airport B, yet per departure deicing

costs were 73% higher at Airport B than Airport E. Similarly, at Airport A, the 1996-97 deicing
Section 14.0 - Economic Profile

 Cargo aircraft spend significantly longer periods of time on the ground, typically only “cycling once” per day 25

(compared to a passenger aircraft that might have several take-off/landing cycles per day. Thus, a cargo-only aircraft

may land in the morning, be deiced and anti-iced, then need deicing again before departing that night (42).

 Regional airline respondents to the EPA minisurvey estimated a range of 35 to 50 deicing episodes in the 1997-98 26

deicing season; assuming a 150-day deicing season (e.g., from mid-October through mid-April), these airlines were

undertaking deicing operations of varying intensity every three to four days (note that some episodes may have lasted

more than one day). Presumably deicing operations were less frequent in October and April, and more frequent in

January and February. Northwest Airlines indicates that it deices aircraft almost daily at its Minneapolis hub during the

October to April “deicing season.”

14-36

season was more severe than the 1998-99 season, yet per departure costs were 20% higher in the

1998-99 season. Finally, the deicing costs of cargo-only operations at Airport D are significantly

higher than the other airports.25

EPA also received separate estimates of deicing costs from regional airlines. 

Minisurveys to regional airlines provided estimates of cost per aircraft deiced ranging from $320

to $360 at Northeastern, Midatlantic, and Midwestern regional airports. Although these costs

appear somewhat higher than the estimates provided by ATA (with the exception of Airport D

with cargo-only service), ATA’s estimates include aircraft departures that did not receive

deicing. With that qualification, EPA considers the regional airline estimates similar to those 26

provided by ATA for similar region airports (43).

Regional airline estimates of the percentage of costs accounted for by different

components of deicing operations are not directly comparable to ATA estimates. Regional

airlines provided estimates of the direct cost of deicing operations that excluded such items as the

cost of delays, and the estimated increase in landing fees attributable to deicing operations. 

However, it can be noted that whereas ATA estimated that the percentage of costs attributable to

labor (28.5%) were of roughly the same magnitude as costs attributable to materials (24.7%),

regional airlines attributed a significantly larger percentage of direct deicing costs to materials

(43). The reason for these differences are not immediately apparent. 

Regional airlines also provided estimates for the price of some ethylene and

propylene glycol-based deicing fluids. For Type I ethylene glycol-based fluids, the price was
Section 14.0 - Economic Profile

 ATA argued that estimates based on snowfall underestimate the true national costs of deicing because zero snowfall 27

implies zero deicing costs, yet airlines do incur deicing costs even with zero or minimal snow, as can be seen in Table

14-17.

14-37

estimated in the $4.70 to $5.00 per gallon range; propylene glycol-based Type I fluids were

somewhat more expensive in the $5.00 to $5.30 per gallon range. For Type II ethylene glycolbased anti-icing fluids, the price was estimated in the $6.15 to $6.30 range. For Type IV

propylene-glycol based anti-icing fluids, the price was estimated in the $7.45 to $7.60 range (43).

As discussed in detail above, ATA extrapolated deicing costs at 236 other U.S.

airports at which air carriers maintain operations using the airport-specific deicing costs per

deicing season operation and the three measures of weather severity. Table 14-18 summarizes

ATA’s estimates of U.S. national air carrier deicing costs. Estimates of national deicing costs

range from a low of $437 million in the 1997-98 deicing season (measured using days less than

32E F), to a high of $549 million in the 1996-97 deicing season (measured using HDD).27

National deicing costs averaged well under 1% of total national operating costs for these three

deicing seasons. However, because of the small profit margins in the air transportation industry,

deicing costs ranged from 9% to almost 20% of net industry profits in the same time period.

14.2.4 Air Transportation Industry Trends

Following is a brief discussion of some trends that may significantly impact the air

transportation industry, and its deicing operations, over the next few years.

14.2.4.1 Projected Industry Growth

Between 1998 and 2009, the FAA projects that the demand for air transportation

services, as measured by domestic passenger enplanements, will grow faster than that projected

for U.S. Gross Domestic Product (GDP), 3.5% compared to 2.3% for GDP. For the 2010 to

2020 period, both air travel demand and GDP growth is projected to slow, to 2.9% and 1.9%
Section 14.0 - Economic Profile

 Air transportation growth projections are largely dependent on GDP growth projections; the FAA based its projections 28

on an average of DRI/McGraw-Hill’s and The WEFA Group’s forecasts.

 Although Boeing sees little growth in average aircraft capacity, the FAA expects average aircraft capacity to grow by 29

approximately two seats per year, from 142.6 seats to 166.6 seats in 2009.

14-38

respectively (44). Boeing projects somewhat slower growth for North American air 28

transportation (approximately 2.9%) while Airbus forecasts significantly slower growth

(approximately 2.2%) than the FAA between 1998 and 2017 (45, 46).

Of particular interest is that regional and commuter airline growth is forecast to

exceed large commercial airline growth, approximately 5.5% compared to 3.5% for large airlines,

between 1998 and 2009. Also, because the demand for air travel is expected to grow faster than

air carrier fleets during the forecast period, air carriers are expected to accommodate some of the

increased demand through higher load factors and more intensive utilization of existing aircraft

(44, 45). To the extent that increased passenger demand is accommodated through more 29

intensive utilization of existing aircraft, rather than using fewer aircraft with larger passenger

capacity, more flight operations will be required to meet the increased demand for air

transportation. Total operations and deicing operations would then be expected to grow more

quickly with projected passenger demand, rather than more slowly with projected aircraft fleet

size. ATA notes, however, that historically operations have grown more slowly than passenger

demand.

14.2.4.2 Regional Jets

Regional jets (RJs) are smaller jet aircraft with seating capacities ranging from 32

seats to approximately 100 seats. RJs are largely being ordered by regional and commuter

airlines, both to replace existing turboprop aircraft in their fleets, and to expand their fleets. RJs

should result in increased service on smaller routes now generally served by turboprops. RJs offer

lower operating costs per ASM than turboprops, resulting in lower cost service on smaller routes

(15, 45). RJs are especially competitive on “long thin” routes. Comair, for example, estimates

that it can break even operating an RJ on such a route with 21 passengers; if its affiliate Delta
Section 14.0 - Economic Profile

14-39

operates a Boeing 737 on the same route, the larger aircraft would require 81 passengers to break

even (47). Perhaps as importantly, RJs are more popular with the public because they are

perceived as safer and more comfortable than turboprops; one commuter airline’s research

suggested demand on some of their routes would grow by perhaps 20% simply due to the

“turboprop avoidance factor” (47).

The importance of RJs is reflected in the faster growth for regional and commuter

airlines projected by FAA. The combination of lower operating costs (an increase in supply), and

increased demand on routes serviced with RJs could result in significantly increased air

transportation service to smaller airports. This could have two implications for aircraft deicing. 

First, due to the increasing demand for service by small aircraft, the number of deicing operations

will grow more quickly than overall passenger demand because smaller aircraft will carry fewer

passengers per flight. (Note that because smaller aircraft require less deicing fluid than larger

aircraft, the total volume of ADF-contaminated wastewater generated may not increase

significantly.) Second, because the comparative advantage of RJ aircraft is in serving smaller

airports with insufficient traffic to justify larger aircraft, more deicing operations will be

undertaken at these smaller airports than is currently performed.

14.2.4.3 Free Flight

Free Flight is a concept that will reduce pilots’ reliance on air traffic controllers

under most conditions, allowing them to choose the most efficient and economical route for their

flight. Potentially this is an important development because delays due to inefficiency in the

current Air Traffic Control system imposes significant costs on airlines (48). By decentralizing

decision-making, and devolving that responsibility, in most circumstances, from the air traffic

controller to the pilot, Free Flight should result in lower operating costs through reduction in

delays and reduced fuel usage. For example, American Airlines was able to reduce fuel costs by

$2.2 million in one year through the use of “negotiated wind routes;” other limited tests of the

concept show substantial fuel savings for participants (49). 
Section 14.0 - Economic Profile

14-40

Due to decreased reliance on air traffic controllers, Free Flight may also allow air

traffic capacity to expand more quickly than the air traffic control system, also saving the air

transportation system significant infrastructure costs. Note that Free Flight will not increase

capacity at airports; airport constraints and slot controls may cause bottlenecks in the system,

decreasing the potential benefit of Free Flight. Free Flight is being implemented slowly, and in

discrete steps; not all technology needed for full implementation of Free Flight has yet been

developed (49). However, to the extent that Free Flight is able to lower airlines’ operating costs,

the resulting increase in air transportation supply could cause air traffic to grow more quickly than

projected over the next 20 years.

14.2.4.4 Competitive Issues

A major issue in the air transportation industry is the degree of competition

existing in the industry and the role of the government in fostering competition. Although

economists may disagree over how competitive the industry is at the present time, most

economists do agree that deregulation has, in general, caused air fares to fall and the quantity

demanded of air transportation to increase (35, 37, 50, 51, 52, 53). In general, this has been

caused by increased competition, both between existing airlines now able to compete head-tohead on routes of their choice, as well as through the entrance of new airlines into the industry

undercutting the fares of existing airlines.

Although the benefits to consumers of deregulation have been large, and to most

economists, indisputable, on a handful of routes competition has remained restricted. Fares on

such routes have found to be significantly higher than comparable routes between other cities (52,

53). Airlines argue that these fare differentials are a result of traveler preferences on those routes,

especially due to business travelers’ willingness to pay a premium for frequent and nonstop

service (53). Industry critics argue that the fare differentials are a result of factors minimizing

competition at these airports including: (1) the dominant market position of a major airline at one

of the airports, usually an operational hub (so-called “fortress hubs”), and (2) restricted access to

an airport because of a lack of available gates at the airport (“gate-constrained”) or FAA-
Section 14.0 - Economic Profile

14-41

mandated limitations on landing slots (“slot-constrained” (34, 53, 54)). GAO has identified six

airports as gate-constrained: Charlotte, Cincinnati, Detroit, Minneapolis, Newark, and Pittsburgh,

and four more as slot-constrained: Chicago O’Hare, LaGuardia, Kennedy, and Ronald Reagan

Washington National (52). The FAA is examining ways of reducing gate and slot constraints at

airports. 

Evidence concerning a potential “hub premium” at such airports is mixed. Large

hub premiums have been found in highly publicized studies by Borenstein and by the GAO;

however, these studies appear to be badly flawed (35, 55). Morrison and Winston found a small

but significant hub premium, and confirmed this result after adjusting GAO’s study for

methodological errors. On the other hand, a recent study by Gordon and Jenkins found a small

but significant “hub discount” (55). 

Other explanations of high fares have focused on allegations of anticompetitive

behavior of incumbent airlines. Incumbent airlines have engaged in a variety of business practices,

such as the use of frequent flier miles, bias in computer reservation systems, special bonus

commissions to travel agents reaching certain goals for bookings on a specific airline, and

codesharing alliances that can potentially provide them with a competitive advantage, especially

against startup airlines. It should be noted that many of these business practices, including the

previously discussed hub-and-spoke route systems, frequent flier programs, and computer

reservation systems have benefited consumers as well as served as tools of inter-airline

competition (53). 

Of particular concern to some industry observers are allegations that incumbent

airlines have engaged in predatory pricing behavior to drive new entrants out of markets. In

short, incumbents have been accused of drastically cutting fares, perhaps even below costs, and

dramatically increasing service on certain routes to a level with which new entrants cannot

compete. After the new entrants are forced from the market, incumbents quickly revert to

previous fare and service levels (52, 56). The U.S. Justice Department recently sued American

Airlines for such antitrust violations, and is probing Delta and Northwest Airlines as well (57).
Section 14.0 - Economic Profile

14-42

Concerns of anticompetitive behavior have been particularly prevalent in some

quarters due to the failure rate of low-fare startups – point-to-point low-cost airlines, such as

People’s Express that try to emulate Southwest Airline’s operating philosophy (36). The DOT

believes that the success of airline deregulation has largely been due to low-fare startups (50). 

Incumbent airlines argue that the failure of low-fare airlines has been due to mismanagement

(noting that the failure rate for new air carriers is virtually identical to the failure rate for new

businesses of all types) and consumer preference for traditional airlines (15). Furthermore,

incumbent airlines believe the decrease in new entrants is attributable to the slowdown in DOT

approval of new airlines after the 1996 ValuJet crash (15, 48). Clearly, many of the low-fare

airline failures – including People’s Express – have been caused by their business shortcomings

(53). However, there is concern among industry observers that anticompetitive behavior has also

been responsible for a lack of competition in certain markets (53, 56).

The DOT has proposed guidelines indicating practices that it will consider

potential anticompetitive behavior. Under these proposed guidelines, which it continues to study,

DOT would investigate such practices and take action against the airline if necessary (56). ATA

argues that the DOT’s guidelines are vague and contradictory to established U.S. antitrust law; it

perceives DOT’s guidelines as a move towards re-regulating the airline industry (15). Other

observers, while also concerned with anticompetitive behavior in the industry, share ATA’s

concern that DOT’s guidelines are too vague and will result in unnecessary increased regulation;

these observers agree with ATA that allegations of illegal anticompetitive behavior should remain

within the purview of the U.S. Department of Justice (53). 

There is little or no support among economists for significant re-regulation by

DOT of airline competition, although they do express concern about a relatively limited number of

issues (35, 53). Indeed, many economists would argue that the historically low rate of return

earned in the airline industry is inconsistent with allegations of market power that can

systematically generate substantial price markups over cost. However, the key point for the

purpose of this study is that the airline industry is facing intense scrutiny on a number of highprofile, potentially volatile issues. It is possible that government agencies could respond to these
Section 14.0 - Economic Profile

14-43

issues by dramatically increasing regulatory oversight of airline competition. A fundamental

change in the government’s relationship with the air transportation industry could cause such

significant changes to the structure and conduct of the industry that the state of the industry may

appear, after a period of adjustment, quite different than reported in this profile. 

14.2.5 Analytic Issues

Section 14.2.5 discusses three analytic issues EPA will face should it choose to go

forward with an effluent guideline regulation for airport deicing operations. The impacts of a

potential regulation are unlikely to be measurable in terms of facility closures; Section 14.2.5.1

describes how impacts are likely to be incurred in the airline industry, and how they might be

analyzed. Section 14.5.2.2 revisits the issue of cost pass-through, this time, however, focusing on

the pass-through of costs from airlines to their passengers. Finally, Section 14.2.5.3 briefly

discusses how the compliance costs of a potential regulation may affect the decision to deice.

14.2.5.1 Assessing Potential Regulatory Impacts 

In previous effluent guidelines efforts, EPA has typically relied on facility-level

cash flow analysis to project regulatory impacts; this is not likely to be appropriate for the airport

deicing operations industry. In manufacturing and many service industries, the cost of regulatory

compliance is incurred by the facility, which may be able to recover some of its costs through

increased price to customers. Facility-level impacts can be projected by analyzing the net impact

on facility costs and revenues and comparing the result with some well-defined benchmark (e.g., is

estimated post-regulatory cash flow greater than the facility’s salvage value). In the airport

deicing operations industry, the facility is the airport, but the product – air transportation services

– is provided by intermediaries, the different airlines that use the airport. 

The financial arrangements between airports and airlines mean that facility closures

(e.g., airport closures) are unlikely to be an impact of effluent guidelines on the industry. Most

commercial service airports, those most likely to be impacted by an effluent guideline regulation,
Section 14.0 - Economic Profile

Clarification by ATA of airline pricing policy is necessary to fill out the details of this analysis. At an EPA meeting 30

with ATA, for example, airline representatives stated that airlines compare yield with cost per available seat mile. 

However, these cost and revenue measures, while closely related, do not share a common denominator and are therefore

14-44

charge rents and fees on a residual cost basis. Airlines are bound by contract with the airport to

pay any airport operating costs in excess of revenues, typically in the form of higher landing fees. 

Because of this financial structure, airports do not earn a profit or loss in the traditional

accounting definitions of those terms, nor are they likely to go bankrupt (Section 14.1.2). 

Airports may incur other impacts from such a regulation, as discussed below, but facility closure

is unlikely to be one of them. 

Effluent guidelines regulating the airport deicing operations industry would likely

result in increased operating costs to airlines, whether indirectly in the form of increased landing

fees at airports or directly as increased costs of deicing. Such increased operational costs are

likely to be at least partially passed on to the ultimate customer – the airline passengers – in the

form of higher ticket prices. ATA estimates that the overall price elasticity of demand for air

transportation is approximately unit elastic (i.e., -1.0), thus a 1% increase in ticket prices will on

average cause a 1% decrease in the quantity of air transportation demanded (15). However, this

will vary on individual routes; on some routes where the typical passenger is flying for vacation

purposes (i.e., relatively elastic demand), the impact may be larger, while on routes flown by

business travelers (i.e., relatively inelastic demand), the impact may be much smaller, but

measurable. In the airline industry, however, a 1% decrease in passenger demand translates into

empty seats and lost revenues on existing flights – with little decrease in operating costs – not a

1% reduction in flights and operating costs (38). Because empty seats reduce revenues more than

costs, airlines may respond to decreased demand by reducing service (e.g., providing less frequent

service, or using a turboprop instead of a jet) or terminating service on certain routes. 

The complexities of airline pricing policies are one aspect of the difficulty in

assessing potential regulatory impacts. Airlines calculate the viability of a route by comparing per

unit revenues (i.e., yield, equal to revenue per revenue passenger mile) with the per unit cost of

providing that service (i.e., cost per available seat mile (15)). There is a wide range of publicly 30
Section 14.0 - Economic Profile

not directly comparable. In addition, while the discussion above is in the context of passenger airline service, even

airlines offering primarily passenger service generate significant revenues from cargo service (15). Impacts on cargo

service should be included in the economic analysis. 

14-45

available information that would enable EPA to estimate per unit revenues and costs for individual

airlines. However, such overall system-wide data would not enable EPA to estimate routespecific impacts. Unit costs, for example, are largely a function of the type of service offered on

that route, especially flight length and aircraft type (the choice of aircraft type is not completely

independent of flight length). For example, one analyst estimates that United Airlines’ unit costs

on routes of 500 miles or less are 23% greater than its overall system-wide average (58). 

With the exception of low-cost single-fare airlines such as Southwest, unit

revenues are determined by the complex procedure known as yield management. An aircraft seat

is a perishable good just like fresh produce – once an aircraft leaves the gate, that seat’s earning

potential is lost for good. The marginal cost of filling an aircraft seat is very low, comprised of

incremental fuel burn, baggage handling, ticketing and other incremental costs (assuming the

flight’s departure is not dependent on whether that passenger is on it). Therefore, an airline has

incentive to offer very low fares rather than fly with empty seats that represent a forgone

opportunity to earn revenue. However, filling an entire aircraft with passengers paying such a low

fare to avoid empty seats is neither desirable, nor will it cover the operating costs of the aircraft

(38). Filling a seat with a low-fare passenger when it could have been filled by a passenger willing

to pay a higher fare also represents a lost opportunity to earn revenue. “Yield management” is the

complex way in which airlines determine how many blocks of seating on each flight to offer at

each fare in order avoid the twin pitfalls of lost revenue-earning opportunities (i.e., in economic

terms, airlines practice “price discrimination” (59)). Because of yield management, it would be

difficult to reliably determine the “average fare” on a specific route without obtaining airline and

route specific data on realized per unit revenues. 

Other factors contribute to the complexity of yield management. Two routes of

similar length (and presumably similar unit costs) may realize dramatically different average fares

due to characteristics of the routes. As discussed above, perhaps the most important factor is the
Section 14.0 - Economic Profile

14-46

existence of or lack of competition on a route. It has been documented in numerous studies that

average fares on routes without competition between major passenger airlines are substantially

higher than average fares on routes with competition (15, 35, 50, 60). Second, the type of traffic

on a route will affect average fares; the demand for vacation travel is much more price-elastic than

business travel, which limits the ability of airlines to increase fares on routes dominated by

vacationers (35, 59). Finally, airlines judge the viability of routes based on how they fit in their

overall route structure. What is considered an acceptable spread between unit costs and revenues

on one route may not be acceptable on another depending on the importance of the route within

the overall scheme of the airline’s system (39).

Other things constant, increased deicing costs, regardless of whether they are

incurred indirectly through increased landing fees or directly through increased deicing costs, will

decrease the airlines’ margin between per unit cost and revenue. If a route is already operated on

a slim margin, then the increased costs of deicing may be sufficient for an airline to reduce or

terminate service (15); these are potentially the major impacts of an effluent guideline on the

industry. In addition, passengers will most likely have to pay higher fares, in some cases for lower

quality service (i.e., less frequent service, or a downgrade from jet to turboprop service). Finally,

reduced or terminated service will indirectly affect airport revenues and employment even if the

airport is unlikely to close. All these impacts would have to be evaluated.

To properly assess potential regulatory impacts, EPA would need airline-specific

data concerning unit costs and revenues of routes using each airport, for each airline using that

airport. To perform a systematic airport-specific modeling effort would likely require a very large

data-collection effort. EPA identified 212 airports with potentially significant deicing/anti-icing

operations. There are 13 major airlines, plus approximately another 85 national, regional, and

small certificated/commuter airlines with thousands of routes. 

One potential solution to this data problem would be to focus analysis on a small

number of representative airports using the classification system based on operations and weather

developed for this study. By focusing on a small number of airports, EPA could hopefully obtain
Section 14.0 - Economic Profile

An opinion article by Robert Bork in the Wall Street Journal, and the subsequent rejoinders by Gerald Smith and 31

Alfred Kahn concerning the U.S. Justice Department’s antitrust case against American Airlines illustrate the difficulty of

accurately allocating costs among airline’s routes (54, 61, 62).

14-47

more detailed information on airline routes using that airport (e.g., number of flights with yield

and per unit cost figures and type of aircraft used – the larger the aircraft the higher the landing

fee) to model impacts on airline service to that airport. Under this modeling strategy, EPA may

also have to estimate incremental compliance costs at other airports on that route (i.e., some

routes may incur increased compliance costs at both airports on a route, Boston-to-Chicago for

example, while other routes would likely incur costs only at one end, Chicago-to-Orlando for

example).31

An alternate approach to analyzing route costs and revenues may also be viable. 

DOT maintains databases containing data on passengers fares and distances by city origindestination pairs that may be usable for determining airline route revenues. DOT does not

maintain similar information for operating costs between city pairs; however, one article has been

identified that estimates airline unit costs by length of flight based on DOT’s Domestic Fare

Structure Costing Program (Version 6) using publicly available information (58). This may

provide EPA with a template for performing similar calculations. Note that neither the accuracy

of this methodology nor the availability of DOT’s cost model have yet been determined. 

14.2.5.2 Airline-to-Passenger Cost Pass-Through

Cost pass-through (CPT) from airports to airlines is discussed in Section 14.1.2.3. 

However, a second form of CPT needs to be considered: CPT to airline passengers. This can

take three forms: passengers may incur direct CPT from airports (e.g., increased parking fees or

passenger facility charges), indirect CPT from airports through airlines (i.e., higher landing fees

due to ADF collection, containment, or treatment leading to increased ticket prices), and airlines

may directly incur higher deicing operation costs (e.g., higher ADF costs) that are also passed

through to passengers in the form of higher ticket prices. The second and third types of CPT are

analytically similar. 
Section 14.0 - Economic Profile

As of calender year 1996, 54 of 71 large and medium hubs had already imposed PFCs (ACAIS, 1997); however, there 32

has been discussion of increasing the maximum PFC to $4 or even $6 (63). Should this happen, incremental increases

in PFCs – if they can be attributed to deicing operation costs, and not other capital programs – would be part of the

regulatory impact on consumers.

Compliance costs incurred by airports and not passed through to airlines in the form of higher landing fees may still 33

have impacts, although they may be more difficult to assess. In general, many airports do not have sufficient access to

capital to pay for existing improvement and expansion plans; by not passing compliance costs through to airlines, an

airport probably is paying for improvements by postponing other capital improvements. The impact of postponed or

displaced capital improvements may be difficult to assess, but nonetheless could still potentially result from airport

deicing operations effluent guidelines. For example, a number of airports are facing capacity constraints; the potential

impact of postponed airport expansion plans, such as slower growth and higher fares, could be substantial, even though

they may be difficult to quantify.

14-48

Airports directly pass through capital costs to passengers in the form of passenger

facility charges (PFCs). Because the PFC is collected as part of the ticket cost, the passenger

probably does not distinguish between an increase in travel price caused by the PFC and an

increase in travel price caused by an airline fare increase. However, if an airport incurs

compliance costs that are not passed on to airlines in the form of higher landing fees, but instead

pays for improvements through imposing or increasing PFCs, passengers still pay higher ticket

prices. Airports can also increase revenues through charges on concessions, parking, and other 32

fees. Because passengers are better able to avoid paying these higher fees by choosing not to

park at the airport or not buying items at airport concession stands, CPT from this source may be

small. The link between these increased costs of air travel and demand for air travel has not been

examined.33

CPT from the airlines to their passengers is conceptually easier to estimate. In a

simple market transaction, CPT is determined by the relative price elasticity of supply and

demand. However, airlines are able to charge different prices to different types of passengers

precisely because different types of travelers have different price elasticities of demand. As

previously mentioned, business travelers have fairly inelastic demand, which enables airlines to

increase their fares more with little loss in travel. CPT for business travelers should therefore be

larger than for vacation travelers with much more elastic demand. The difficulty in applying this

to specific airline routes is that different routes are likely to carry different mixes of passengers

thus affecting the CPT for that route.
Section 14.0 - Economic Profile

 Note that at least one airport in Canada has implemented a deicing surcharge on all flights. 34

14-49

An assumption of 100% CPT from airports to airlines and zero CPT from airlines

to passengers would be the most tractable to model, and would probably be the most conservative

assumption as well. The maximum PFC at one airport probably represents a small percentage of

the average airfare, and the majority of significant airports have already imposed PFCs. Thus, any

incremental CPT from airports directly to passengers due to compliance with deicing operations

effluent guidelines is likely to be small. The calculation of CPT from airlines to passengers is

highly problematic because the relevant price elasticity of demand to determine CPT is route

specific; the overall price elasticity of demand estimated by ATA provides little guidance in this

case. The drawback of assuming 100% CPT from airports to airlines and zero CPT from airlines

to passengers is that almost all projected impacts would be incurred by airlines. Even if the total

dollar value of projected regulatory impacts is no higher under alternative assumptions about

CPT, the distribution of impacts among airports, airlines, and passengers would differ. 

14.2.5.3 Incentives

Both the airlines and the FAA have expressed their opinion that any proposed EPA

effluent guidelines regulating discharges from airport deicing operations must not affect aircraft

safety (i.e., the decision to deice aircraft and how much fluid to use). They are concerned that

effluent guidelines potentially limiting the discharges of wastewater containing deicing agents may

increase the cost of deicing operations and create an incentive for airlines to find ways to decrease

the quantity of deicing agents used and deicing operations performed. However, this is unlikely

due to the large liability surrounding air safety. The liability lies with the airline to ensure that an

increase in the cost of deicing does not affect a pilot’s decision to deice and judgement as to

whether sufficient deicing has been performed. 

However, a likely scenario may be that any compliance costs would be passed on

to the airlines in the form of higher landing fees on all flights, not just those flights requiring

deicing. There should be no incentive for airlines to change their deicing decisions under such a 34
Section 14.0 - Economic Profile

14-50

scenario. It is the cost of using the airport regardless of whether deicing is performed or not that

would increase. This could lead to a reduction or termination of service at the airport (although

the extent to which costs are spread over all landings at the airport may help to mitigate those

impacts), but should not affect the deicing decision.

14.3 References

1. Telephone conversation between Sharon Glasgow, FAA Office of Airports,

Airport Capacity Branch, and Calvin Franz, ERG. September 15, 1998.

2. Federal Aviation Administration. National Plan of Integrated Airport Systems

(NPIAS) 1993-1997. Washington, DC. April 1995.

3. Federal Aviation Administration. National Plan of Integrated Airport Systems

(NPIAS) 1990-1999. Washington, DC. 1992.

4. Federal Aviation Administration. Air Carrier Activity Information System

Database (ACAIS.XLS). Washington, DC. 1999.

http://www.faa.gov/arp/410home.htm.

5. Federal Aviation Administration. Fourteenth Annual Report of Accomplishments

Under the Airport Improvement Program: Fiscal Year 1995. Washington, DC. 

December 1996. http://www.faa.gov/arp/500home.htm.

6. Federal Aviation Administration. National Plan of Integrated Airport Systems

(NPIAS) 1998-2002. Washington, DC. 1999.

http://www.faa.gov/arp/410home.htm.

7. Federal Aviation Administration. Operations data for 449 airports from 4/1/97 to

3/30/98. File provided by FAA to EPA. 1998. 

8. National Oceanic and Atmospheric Administration. Mean Annual Snowfall Data. 

1998. http://www.noaa.gov/.

9. Wells, Alexander T. Airport Planning and Management. Third Ed., New York:

McGraw-Hill. 1996.

10. Telephone conversation between Wayne Heibeck, FAA Office of Airports, and

Calvin Franz, ERG. September 15, 1998.
Section 14.0 - Economic Profile

14-51

11. Office of Inspector General. Management Advisory Memorandum on City of Los

Angeles’ Department of Airports Revenue Retention (Report Number: R9-FA-7-

005). Washington, DC. March 7, 1997.

12. American Association of Airport Executives. AAAE Survey of Airport Rates and

Charges, 1997-1998. Alexandria, VA. 1999.

13. Airport Surveys. Responses to EPA Airport Surveys. Various Airports. 1999.

14. Anchorage International Airport. Comments on the U.S. EPA Effluent Guidelines

Airport Deicing Operations Study. November 2, 1999.

15. Air Transport Association of America. Meeting Summary, Air Transport

Association of America, Economics Session. December 16, 1998.

16. U.S. Environmental Protection Agency. Economic Site Visit Report for Chicago

O’Hare International Airport. Draft Final. November 24 , 1998.

17. Federal Aviation Administration. 1998 List of Cargo Aircraft: CY1998 ACAIS

database. Washington, DC. 1998. http://www.faa.gov/arp/A&D-stat.htm.

18. Bureau of Transportation Statistics, Office of Airline Information. Airport

Activity Statistics: 1997. Washington, DC. 1998.

19. U.S. Environmental Protection Agency. Economic Site Visit Report for General

Mitchell International Airport. Draft Final. October 7, 1998.

20. U.S. Environmental Protection Agency. Engineering Site Visit Report for Salt

Lake City International Airport. Draft Final. July 10, 1998.

21. Indianapolis. The Indianapolis Experience: A Small Government Prescription for

Big City Problems. Part 1, Chapter 1, Case Study #12: Airport. 1998. 

http://www.IndyGov.org/mayor/comp/indyexp/part1/chapter1/airport.html.

22. Federal Aviation Administration. Fifteenth Annual Report of Accomplishments

Under the Airport Improvement Program: Fiscal Year 1996. Washington, DC. 

December 1997. http://www.faa.gov/arp/500home.htm.

23. U.S. General Accounting Office. Airport Financing: Funding Sources for Airport

Development (Report GAO/RCED-98-71). Washington, DC. March 1998.

24. Engineering News & Record. “Why Enable Head-tax Addicts?” Viewpoint by E.

Merlis, Air Transport Association of America. October 5, 1998.
Section 14.0 - Economic Profile

14-52

25. American Association of Airport Executives. Airline Competition: A Statement of

AAAE Principles. Alexandria, VA. 1999.

26. Federal Aviation Administration. An Assessment of Innovative Financing Options

for the Airport Improvement Program. Washington, DC. March 1996. 

http://www.faa.gov/arp/app500/finalcom/index.htm.

27. Federal Aviation Administration. FAA Statistical Handbook of Aviation. 

Washington, DC. 1996. http://api.hq.faa.gov/handbook/1996.

28. Telephone conversation between Bernie Stankus, DOT, Office of Airline

Information, and Calvin Franz, ERG. September 17, 1999.

29. Bureau of Transportation Statistics, Office of Airline Information. Air Carrier

Financial Statistics: Quarterly (Yellow Book). Washington, DC. June 1998.

30. Air Transport Association of America. Airline Handbook. Washington, DC. 

1999. http://www.air-transport.org/public/handbook.

31. Bureau of Transportation Statistics, Office of Airline Information. Air Carrier

Industry Scheduled Service Traffic Statistics: Quarterly (Blue Book). Washington,

DC. June 1998.

32. Bureau of Transportation Statistics, Office of Airline Information. Air Carrier

Traffic Statistics: Monthly (Green Book). Washington, DC. June 1998.

33. Air Transport Association of America. ATA Annual Report, 1994. Washington,

DC. 1994. http://www.air-transport.org/public/industry.

34. Air Transport Association of America. ATA Annual Report, 1998. Washington,

DC. 1998. http://www.air-transport.org/public/industry.

35. Morrison, S. A., and C. Winston. The Evolution of the Airline Industry. 

Washington, DC: The Brookings Institute. 1995.

36. Petzinger, T. Hard Landing. New York: Times Business. 1996.

37. Shepherd, W. G. & J. W. Brock. “Airlines” in The Structure of American

Industry. Ninth Ed. W. Adams and J. W. Brock, eds. Englewood Cliffs, NJ:

Prentice Hall. 1995.

38. Crandall, R.L. “The Unique U.S. Airline Industry” in Handbook of Airline

Economics. First Ed. D. Jenkins, ed. New York: Aviation Week Group of The

McGraw-Hill Companies. 1995.
Section 14.0 - Economic Profile

14-53

39. Air Transport Association of America. Data & Statistics. Washington, DC. 

1998. http://www.air-transport.org/data/.

40. Office of Aviation Analysis. Airline Quarterly Financial Review. U.S. Department

of Transportation. Quarterly. 

41. Air Transport Association of America. Response by Air Transport Association

and Selected Major Airlines to EPA Revised Questionnaire. July 21, 1999.

42. Air Transport Association of America. Conference Call: Follow-up on Questions

Concerning ATA’s Response to the EPA’s Aircraft Deicing Operations

Questionnaire. October 15, 1999.

43. Regional Airline Surveys. Responses to EPA Regional Airline Surveys. Various

Regional Airlines. 1999.

44. Federal Aviation Administration, Office of Aviation Policy and Plans. FAA LongRange Aviation Forecasts, Fiscal Years 2010, 2015, and 2020. FAA-APO-98-9. 

Washington, DC. June 1998.

45. Boeing. Current Market Outlook. Seattle: Boeing Commercial Airplane Group. 

1998. http://www.boeing.com/cmo.

46. Airbus. Global Market Forecast 1998-2017. France: Airbus Industrie. April

1998. http://www.airbus.com.

47. Office of the Assistant Secretary for Aviation and International Affairs. Profile:

Regional Jets and Their Emerging Roles in the U.S. Aviation Market. 

Washington, DC. June 1998.

48. Air Transport Association of America. Comments on the Draft Effluent

Guidelines Airport Deicing Operations Study. November 4, 1999.

49. Federal Aviation Administration. Free Flight. Washington, DC. 1998. 

http://www.faa.gov/freeflight.

50. Federal Aviation Administration. The Low-Cost Airline Service Revolution. 

Washington, DC. April 1996.

51. U.S. General Accounting Office. Airline Deregulation: Changes in Airfares,

Service, and Safety at Small, Medium-Sized, and Large Communities. 

(GAO/RCED-96-79). Washington, DC. April 1996.
Section 14.0 - Economic Profile

14-54

52. U.S. General Accounting Office. Airline Deregulation: Changes in Airfares,

Service Quality, and Barriers to Entry. (GAO/RCED-99-92). Washington, DC. 

March 1999.

53. Transportation Research Board. Entry and Competition in the U.S. Airline

Industry: Issues and Opportunities. Special Report 255 (Prepublication Copy). 

Washington, DC: National Academy of Sciences, National Research Council. 

1999.

54. Wall Street Journal. “This Antitrust Theory Won’t Fly.” May 17, 1999. 

55. Gordon and D. Jenkins. Untitled Study of Hub Premiums. Ashburn, VA: The

Aviation Institute, The George Washington University. 1998. 

http://gwuva.baweb.com/academics/aviation-institute/article_study.html.

56. U.S. Department of Transportation. Competition in the U.S. Domestic Airline

Industry: The need for a policy to prevent unfair practices. Washington, DC. 

1998.

57. Wall Street Journal. “U.S. Sues American Air in Antitrust Case.” May 14, 1999.

58. Roberts, P. and M. Roach. “Low Costs – The Key to Airline Success as Pricing

Becomes Increasingly Market Driven,” in Handbook of Airline Economics. First

Ed. D. Jenkins, ed. New York: Aviation Week Group of The McGraw-Hill

Companies. 1995.

59. Cross, R. G. “An Introduction to Revenue Management,” in Handbook of Airline

Economics. First Ed. D. Jenkins, ed. New York: Aviation Week Group of The

McGraw-Hill Companies. 1995.

60. U.S. General Accounting Office. Airline Deregulation: Barriers to Entry Continue

to Limit Competition in Several Key Domestic Markets (GAO/RCED-97-4). 

Washington, DC. October 1996.

61. Wall Street Journal. “Opportunity Costs in American’s Move.” May 28, 1999. 

62. Wall Street Journal. “American and Predatory Pricing.” June 16, 1999. 

63. Wall Street Journal. “Airports, Airlines Rev Up for Duel Over Funding Plans.” 

August 31, 1999.
14-55

Section 14.0 - Economic Profile

Table 14-1

Passenger and Cargo Activity by FAA Airport Definition, 1997

Airport Type Boardings (Brd) by Type by Type by Type by Type by Type Airports (b) Cargo

FAA Airport

Definitions Based on Number of Total Average Maximum Minimum Total Gross

Percentage of National Airports Boardings Boardings Boardings Boardings Number of Landed Weight of

Passenger Activity Cargo-Only Activity (a)

Primary, Large Hub

 % of total

1% <= Brd 30 439,556,180 14,651,873 33,249,963 6,467,195 28 53,580,799,092

 68.6%

Primary, Medium Hub

 % of total

0.25% <= Brd <1% 40 132,472,093 3,311,802 6,318,523 1,634,578 29 53,966,253,749

 20.7%

Primary, Small Hub

 % of total 

0.05% <= Brd < 0.25% 71 46,968,440 661,527 1,553,700 324,521 34 19,371,974,805

 7.3%

Primary, Nonhub

 % of total

10,000 < Brd < 0.05% 276 21,191,850 76,782 317,199 10,019 9 3,119,938,255

 3.3%

Nonprimary Commercial

Service (c)

 % of total

2,500 <= Brd<= 10,000 112 550,755 4,917 9,724 2,509 2 1,593,027,497

 0.1%

Noncommercial Service

 % of total

NA 1,186 824,388 695 81,416 0 4 1,588,610,350

 0.1%

Total 1,715 641,563,706 106 133,220,603,748

(a) Data for “qualifying” airports only-those airports that land a minimum of 100 million pounds of cargo-only aircraft; other airports may land cargo-only aircraft. Gross landed weight

cargo refers to the rated landing weight of the aircraft, not the weight of the cargo carried in the aircraft.

(b) Number of airports within FAA type landing at least 100 million pounds of cargo-only aircraft in addition to their passenger activities (e.g., there are 30 large hubs based on passenger

activity; 28 of these large hubs also qualified as significant cargo-only airports).

(c) Noncommercial service airports reporting boarding activity in the ACAIS database; the NPIAS contains over 2,800 noncommercial service airports.

Source: Reference (4).
14-56

Section 14.0 - Economic Profile

Table 14-2

Growth of Total and Average Enplanements at Commercial Service Airports by FAA Definition, 1993 - 1997

Passenger Enplanements Enplanement Growth Rates

Year 1993 1994 1995 1996 1997 1993 1994 1995 1996 1997 Average

Total Boardings (a) 528,920,496 573,575,959 586,326,851 621,613,161 641,563,706 NA 8.4% 2.2% 6.0% 3.2% 5.3%

Total Enplanements

 # of Airports

527,984,216 572,608,645 585,347,291 620,410,923 640,739,318 NA 8.5% 2.2% 6.0% 3.3% 5.3%

566 575 566 540 529

Total Enplanements by Airport Type Growth Rates, Total Enplanements

Large Hub Primary

 # of Airports

341,729,124 380,292,229 393,110,251 418,425,819 439,556,180 NA 11.3% 3.4% 6.4% 5.0% 7.2%

27 29 29 29 30

Medium Hub

Primary

 # of Airports

118,290,399 126,220,983 129,792,590 137,813,925 132,472,093 NA 6.7% 2.8% 6.2% -3.9% 3.0%

38 40 42 42 40

Small Hub Primary

 # of Airports

49,045,057 44,941,969 41,489,614 43,807,189 46,968,440 NA -8.4% -7.7% 5.6% 7.2% -1.1%

83 71 67 70 71

Nonhub Primary

 # of Airports

18,193,093 20,396,930 20,197,540 19,748,437 21,191,850 NA 12.1% -1.0% -2.2% 7.3% 4.1%

269 281 273 272 276

Nonprimary

 # of Airports

726,543 756,534 757,296 615,553 550,755 NA 4.1% 0.1% -18.7% -10.5% -6.0%

149 154 155 127 112

Average Enplanements by Airport Type Growth rates, Average Enplanements

Large Hub Primary 12,656,634 13,113,525 13,555,526 14,428,477 14,651,873 NA 3.6% 3.4% 6.4% 1.5% 3.9%

Medium Hub

Primary

3,112,905 3.155,525 3,090,300 3,281,284 3,311,802 NA 1.4% -2.1% 6.2% 0.9% 1.6%

Small Hub Primary 590,904 632,985 619,248 625,817 661,527 NA 7.1% -2.2% 1.1% 5.7% 3.0%

Nonhub Primary 67,632 72,587 73,984 72,605 76,782 NA 7.3% 1.9% -1.9% 5.8% 3.4%

Nonprimary 4,876 4,913 4,886 4,847 4,917 NA 0.7% -0.5% -0.8% 1.5% 0.2%

(a) Total boardings include revenue passenger boardings at noncommercial service airports; the difference between total boardings and total emplanements is small.

Average emplanements for all commercial service airports are not included because in this case; when both the numerator and denominator change, the estimate of growth is both

deceptive and irrelevant.

Source: Reference (4).
14-57

Section 14.0 - Economic Profile

Table 14-3

Airport Flight Operations by FAA Airport Definition, 1997

Airport Type Definition Operations Operations Operations Operations Operations Carrier Air Taxi Military GA

Number of Number of

Airports by Airports

FAA Reporting Total Average Maximum Minimum

Non-GA Operations Activity by Airport Definition Airport Definition

Average Operations by Aircraft Type and

Primary, Large Hub

 % of total

30 30 12,920,538 430,685 847,901 209,827 306,706 119,661 4,317 44,424

48.0%

Primary, Medium Hub

 % of total

40 40 5,592,685 139,817 311,088 33,863 86,740 45,926 7,152 82,126

20.8%

Primary, Small Hub

 % of total

71 70 3,967,527 56,679 170,446 5,248 18,501 27,871 10,307 76,084

14.7%

Primary, Nonhub

 % of total

276 157 3,423,075 21,803 107,481 3,160 2,139 13,925 5,739 54,319

12.7%

Nonprimary, Commercial

Service

 % of total

112 11 171,669 15,606 59,783 3,289 2,055 7,822 5,729 104,108

0.6%

Noncommercial Service

 % of total

NA 110 830,379 7,549 105,774 23 185 3,690 3,674 125,831

3.1%

Total 418 26,905,873

Based on 418 airports reporting operations data and contained in ACAIS database; operations data for the 4/1/97 - 3/31/98 time period, enplanements data for CY 1997.

Non-GA operations equals the sum of carrier, air taxi, and military operations.

Source: Reference (4, 7).
Section 14.0 - Economic Profile

14-58

Table 14-4

Airports of Concern, by Operations, Snowfall, and FAA Size Definitions (a)

Snowfall Subtotal by

Categorization FAA Definition Ops “A” Ops “B” Ops “C” Ops “D” Ops “E” Snowfall

Operations Categorization (b)

60" <= snow < 120" Large Hub 1 0 0 0 0 1

Medium Hub 0 1 0 0 0 1

Small Hub 0 0 2 8 3 13

Nonhub 0 0 0 0 14 14

Nonprimary 0 0 0 0 0 0

Noncomm. Svc. 0 0 0 0 3 3

Subtotal 1 1 2 8 20 32

30" <= snow < 60" Large Hub 5 1 0 0 0 6

Medium Hub 0 1 3 2 0 6

Small Hub 0 0 0 4 8 12

Nonhub 0 0 0 1 31 32

Nonprimary 0 0 0 0 1 1

Noncomm. Svc. 0 0 0 0 5 5

Subtotal 5 2 3 7 45 62

15" <= snow < 30" Large Hub 2 7 0 0 0 9

Medium Hub 0 0 5 1 0 6

Small Hub 0 0 0 3 7 10

Nonhub 0 0 1 1 22 24

Nonprimary 0 0 0 0 1 1

Noncomm. Svc. 0 0 1 0 4 5

Subtotal 2 7 7 5 34 55

1" <= snow < 15" Large Hub 2 3 0 0 0 5

Medium Hub 0 2 5 3 0 10

Small Hub 0 0 0 7 7 14

Nonhub 0 0 0 3 25 28

Nonprimary 0 0 0 1 2 3

Noncomm. Svc. 0 0 0 0 2 2

Subtotal 2 5 5 14 36 62

Subtotal by Ops Large Hub 10 11 0 0 0 21

Medium Hub 0 4 13 6 0 23

Small Hub 0 0 2 22 25 49

Nonhub 0 0 1 5 92 98

Nonprimary 0 0 0 1 4 5

Noncomm. Svc. 0 0 1 0 14 15

Subtotal 10 15 17 34 135 211

(a) EPA identified 212 airports of concern based on snowfall and aircraft operations criteria; this analysis is based on 211 airports for

which operations, snowfall, and 1997 ACAIS enplanement data could be matched.

(b) Ops “A”: 425,000 <= Ops < 850,000; Ops “B”: 210,000 <= Ops < 425,000; Ops “C”: 100,000 <= Ops < 210,000; 

Ops “D”: 50,000 <= Ops < 100,000; Ops “E”: 10,000 <= Ops< 50,000.

Source: Reference (4, 7, 8). 
14-59

Section 14.0 - Economic Profile

Table 14-5

Airports with Potentially Significant Deicing Operations, by Operations and Enplanements (a)

Operations (Ops) Number of Non-GA Carrier Air Taxi GA Large

Categorization Airports Operations Operations Operations Operations All Carrier Commuter Air Taxi

Average Operations within Airport Ops Class Average Enplanements within Airport Class

425,000 <= Ops < 850,000 10 567,680 417,349 147,917 43,510 19,296,737 18,303,408 438,088 98

210,000 <= Ops < 425,000 15 320,679 204,549 111,314 49,822 8,991,676 7,896,227 564,009 2,812

100,000 <= Ops < 210,000 17 144,138 71,601 59,534 54,223 2,574,169 2,431,328 124,987 11,571

50,000 <= Ops < 100,000 34 74,236 28,037 33,253 76,477 962,463 854,836 92,478 5,330

10,000 <= Ops < 50,000 135 24,685 4,749 14,037 65,254 168,282 131,397 36,679 189

Total Airports of Concern 211

(a) EPA identified 212 airports with potentially significant deicing operations based on snowfall and aircraft operations criteria; this analysis is based on 211 airports for which operations,

snowfall, and 1997 ACAIS enplanement data could be matched.

Source: Reference (4, 7).
Section 14.0 - Economic Profile

14-60

Table 14-6

Airport Operating Agreements by Airport Type

AAAE Survey Respondents, 1997 - 1998

Airport Type Respondents by Type Residual Compensatory Hybrid Other

Number of Type of Agreement

Large Hub 18 4 5 6 3

Medium Hub 28 14 5 8 2

Small Hub 53 17 16 16 4

Nonhub 96 11 48 20 17

General Aviation

Total 195 46 74 50 26

Source: Reference (12).
14-61

Section 14.0 - Economic Profile

Table 14-7

Airport Revenues by Airport Type for AAAE Survey Respondents, 1997 - 1998

Airport Type s by Type Revenues Revenues Revenues Revenues Expenses Subsidy Income

Number of Average Airline Average Average Average Total Average Total Average Total Average Total

Respondent and Air Cargo FBO/GA Total Other Operating Operating Government Operating

Large Hub

% of total revenues

15 $100,295,007 $5,160,219 $94,381,574 $200,090,311 $106,506,742 $0 $93,583,569

50% 3% 47%

Medium Hub

% of total revenues

27 $14,969,744 $1,840,125 $19,497,502 $38,039,780 $22,145,663 $177,642 $16,071,759

39% 5% 51%

Small Hub

% of total revenues

49 $3,295,032 $842,245 $4,304,924 $8,117,894 $5,916,717 $338,164 $2,539,341

41% 10% 53%

Nonhub

% of total revenues

91 $418,198 $358,565 $735,206 $1,551,172 $1,463,673 $221,324 $308,823

27% 23% 47%

General Aviation

% of total revenues

92 $37,554 $506,232 $264,471 $865,988 $938,491 $218,829 $146,327

4% 58% 31%

Total 274 $119,015,535 $8,707,385 $119,183,677 $248,665,145 $136,971,286 $955,959 $112,649,818

Source: Reference (12).
14-62

Section 14.0 - Economic Profile

Table 14-8

Airport Expenditures for EPA Airport Mini-Questionnaire Recipients, 1997

Large Hubs Medium Hubs Small Hubs Primary Commercial Service Nonhubs

Airport #1 Airport # 2 Airport # 3 Airport # 4 Airport # 5 Airport # 6 Airport # 7 Airport # 8 Airport # 9 Airport #10

Enplanements 16,600,000 15,400,000 12,100,000 5,710,000 2,640,000 818,000 303,000 120,000 64,500 26,700

Non-GA Operations 476,000 445,000 381,000 278,000 214,000 67,000 41,800 21,500 13,400 44,400

Airfield Areas 4.0% 30.0% 13.0% 10.0% 22.6% 21.1% 32.0% 16.0% 3.2% 20.0%

Terminal Areas 16.0% 30.0% 32.0% 20.0% 24.8% 17.0% 20.0% 9.0% 5.9% 13.0%

Hangars, cargo

facilities, and other

areas

1.0% (a) 1.0% 5.0% 3.2% 7.1% 7.0% 6.0% 1.2% 9.0%

General and 

Administrative

9.0% 20.0% 6.0% 24.0% 8.4% 12.6% 16.0% 20.0% 8.3% 20.0%

Other Agencies (b) 3.0% 0.0% 0.0% 6.0% 1.7% 10.5% 2.0% 0.0% 8.7% 0.0%

Debt Service 46.0% 20.0% 29.0% 35.0% 11.6% 13.0% 23.0% 0.0% 2.0% 0.0%

Depreciation 21.0% (a) 18.0% NA 27.7% 18.7% 0.0% 49.0% 6.6% 38.0%

Total 100.0% 100.0% 99.0% 100.0% 100.0% 100.0% 100.0% 100.0% 35.9% 100.0%

(a) Combined with previous answer.

(b) Payments to other agencies for services performed at airport (e.g., police, fire, accounting, legal).

Source: Reference (13).
Section 14.0 - Economic Profile

14-63

Table 14-9

Airport Ownership by Airport Type

AAAE Survey Respondents, 1997 - 1998

Airport Type Type Municipal government Authority Other

Number of

Respondents by Multi- Independent

Type of Ownership

Large Hub 18 10 4 2 2

Medium Hub 31 17 2 8 3

Small Hub 53 34 1 17 1

Nonhub 108 56 8 37 7

General Aviation 130 92 4 23 11

Total 340 209 19 87 24

Source: Reference (12)
14-64

Section 14.0 - Economic Profile

Table 14-10

Airport Capital Expenditures for EPA Airport Minisurvey Recipients, 1997

Large Hubs Medium Hubs Small Hubs Primary Commercial Service Nonhubs

Airport #1 Airport #2 Airport #3 Airport #4 Airport #5 Airport #6 Airport #7 Airport #8 Airport #9 Airport #10

Enplanements 16,600,000 15,400,000 12,100,000 5,710,000 2,640,000 818,000 303,000 120,000 64,500 26,700

Non-GA Operations 476,000 445,000 381,000 278,000 214,000 67,000 41,800 21,500 13,400 44,400

Capital Expenditures $55,423 $537,000 $109,153 $69,600,000 $28,125 $12,000 $2,756 $1,418 $1,452,196 $341

Airport Improvement

Grants

25.7% 9.0% 19.5% 4.0% 14.4% 28.0% 67.0% 75.0% 89.3% 90.0%

Passenger Facility

Charges

33.7% 40.0% 18.8% 13.0% 0.0% 15.0% 18.0% 10.0% 8.3% 5.0%

Other Government

Grants

0.0% 0.0% 0.0% 0.0% 7.7% 0.0% 0.0% 10.0% 2.4% 0.0%

Bonds 33.1% 51.0% 40.9% 80.0% 60.1% 23.0% 0.0% 0.0% 0.0% 0.0%

Rates and Charges 7.5% (c) 12.9% 3.0% 17.7% 28.0% 15.0% 5.0% 0.0% 5.0%

Other Revenue 0.0% (c) 8.0% 0.0% 0.0% 6.0% 0.0% 0.0% 0.0% 0.0%

Total 100.0% 100.0% 100.1% 100.0% 99.9% 100.0% 100.0% 100.0% 100.0% 100.0%

Majority-in-Interest

Clause No No Yes Yes Yes No No (b) No No No

(a) Only airport in sample not charging a PFC, but has applied to start charging a PFC in 2000; all other airports in sample charge maximum PFC ($3).

(b) No majority-in-interest clause, but does have a contractual ceiling on capital expenditures.

(c) Combined with previous answer.

Source: Reference (13).
Section 14.0 - Economic Profile

14-65

Table 14-11

Aircraft in Operation, Hours Flown, and Hours per Aircraft,

Selected Aircraft Type, U.S. Air Carriers, and General Aviation, 1996

Aircraft Type Number of Aircraft Total Flight Hours Hours per Aircraft

Air Carriers

Total 7,478 14,784,409 1,977

4-Engine Turbojet 440 934,572 2,124

% of Total 5.9% 6.3%

3-Engine Turbojet 1,212 2,378,145 1,962

% of Total 16.2% 16.1%

2-Engine Turbojet (a) 3,270 8,715,239 2,665

% of Total 43.7% 58.9%

2-Engine Turboprop 1,639 2,602,374 1,588

% of Total 21.9% 17.6%

General Aviation (b)

Total (Fixed-wing) 160,577 22,719,550 141

2-Engine Turbojet 3,971 1,355,034 341

% of Total 2.5% 6.0%

2-Engine Turboprop 4,551 1,243,572 273

% of Total 2.8% 5.5%

1-Engine Piston 150,980 17,156,396 114

% of Total 94.0% 75.5%

(a)All but 216 air carrier twin engine turbojets carry a minimum of 100 passengers. 

(b) Includes “on demand” air taxis, but excludes commuter aircraft; see text for further details.

Source: Reference (27).
14-66

Section 14.0 - Economic Profile

Table 14-12

Air-Carrier Traffic Statistics by Carrier Type, June 1997 - June 1998

Carrier Number (x 1,000) (x 1,000) (x 1,000) (x 1,000) (%) Aircraft-mile Passenger

Passenger Cargo Revenue Available Passengers 

Enplanements Ton-miles Passenger-miles Seat-miles Load Factor per Miles per

Major 13 534,040 18,491,148 573,632,137 807,270,192 71.1% 112.6 1,074.1

% of Total 9.0% 83.4% 87.7% 92.2% 91.2%

National 28 62,605 2,390,465 35,052,261 53,843,361 65.1% 63.2 559.9

% of Total 19.4% 9.8% 11.3% 5.6% 6.1%

Large Regional 15 7,768 199,559 4,066,632 6,490,996 62.7% 46.0 523.5

% of Total 10.4% 1.2% 0.9% 0.7% 0.7%

Medium Regional 88 36,288 13,937 9,238,469 17,886,124 51.7% 16.4 254.6

(a) 61.1% 5.7% 0.1% 1.5% 2.0%

% of Total

Total 144 640,701 21,095,109 621,989,499 885,490,673 70.2% 98.7 970.8

100% 100% 100% 100% 100%

(a) Including small certificated carriers.

Source: Reference (31).
14-67

Section 14.0 - Economic Profile

Table 14-13

Air-Carrier Financial Statistics by Carrier Type, June 1997 - June 1998

Carrier (x $1,000,000) (x $1,000,000) (x $1,000,000) (x $1,000,000) (%) (x $1,000,000) (%)

Total Total Total Operating

Passenger Operating Operating Operating Profit Net Net Profit

Revenues Revenues Expenses Profit (Loss) Margin Income(a) Margin

Major $74,336.4 $100,506.2 $91,436.0 $9,070.2 9.0% $5,821.6 5.8%

% of Total 88.6% 86.6% 85.9% 94.8% 101.5%

National $5,756.0 $9,837.7 $9,454.8 $382.9 3.9% ($16.7) -0.2%

% of Total 6.9% 8.5% 8.9% 4.0% -0.3%

Large Regional $636.7 $1,706.3 $1,686.7 $19.6 1.1% ($56.5) -3.3%

% of Total 0.8% 1.5% 1.6% 0.2% -1.0%

Medium Regional $62.5 $286.5 $317.8 ($31.3) -10.9% ($36.0) -12.6%

% of Total 0.1% 0.2% 0.3% -0.3% -0.6%

Small Certificated $2,123.2 $2,417.8 $2,276.1 $141.7 5.9% $41.5 1.7%

% of Total 2.5% 2.1% 2.1% 1.5% 0.7%

Commuter $1,029.8 $1,267.3 $1,278.4 ($11.1) -0.9% ($18.5) -1.5%

% of Total 1.2% 1.1% 1.2% -0.1% -0.3%

Total $83,944.6 $116,021.8 $106,449.8 $9,572.0 $5,735.4 4.9%

100.0% 100.0% 100.0% 100.0% 8.3% 100.0%

(a) Operating profit calculates profit before tax and interest payments; net profits are calculated after taxes and interest.

Source: Reference (29).
Section 14.0 - Economic Profile

14-68

Table 14-14

Passenger and Cargo Revenues for ATA Member Airlines, 1997 

(x $1,000,000)

Airline Aircraft (FTEs) Revenues Revenues Revenues Revenues

 Number of Employees Passenger Cargo Operating Passenger

Total %

Majors with Passenger Service

Alaska 78 8,016 $1,256 $82 $1,457 86.2%

America West 103 10,195 $1,753 $51 $1,887 92.9%

American 641 80,321 $14,284 $678 $15,856 90.1%

Continental 388 31,705 $5,686 $205 $6,361 89.4%

Delta 559 62,934 $12,773 $588 $14,204 89.9%

Northwest 405 46,753 $8,722 $788 $9,984 87.4%

Southwest 261 23,749 $3,639 $95 $3,817 95.3%

Trans World 184 22,930 $2,924 $119 $3.328 87.9%

United 571 83,324 $15,069 $891 $17,335 86.9%

U.S. Airways 376 39,734 $7,112 $177 $8,501 83.7%

Majors with Cargo-only Service

DHL 27 8,564 — $664 $1,226 0.0%

Federal Express 581 105,649 — $5,360 $12,730 0.0%

United Parcel Service (a) 214 4,349 — $404 $1,863 0.0%

Nationals with Passenger Service

Aloha 17 1,901 $195 $30 $233 83.7%

Hawaiian 22 2,357 $332 $20 $404 82.2%

Midwest Express 24 1,689 $273 $11 $310 88.0%

Nationals with Cargo-only Service

Airborne Express 105 4,626 — $890 $894 0.0%

Atlas (a) 19 592 — $80 $401 0.0%

Emery (a) 77 967 — $256 $262 0.0%

Evergreen (a) 20 429 — $208 $256 0.0%

Polar Air Cargo 16 481 — $288 $344 0.0%

Excludes members: American Trans Air and Reeve, due to data questions, and 3 non-U.S.-owned associate members.

(a) Includes nonscheduled service.

Source: Reference (34).
14-69

Section 14.0 - Economic Profile

Table 14-15

Operating Revenues, Expenses, and Profits, 1982 - 1997 

(in millions of dollars)

Year (x 1,000,000) Revenues Expenses Profits Expense Net Profit Profit Margin Margin Investment

Revenue Rate of

Passenger Miles Total Op. Total Op. Total Op. Interest Operating Net Profit Return on

1982 259,644 $36,408 $37,141 ($733) $1,384 ($916) -2.0% -2.5% 2.1%

1983 281,829 $38,954 $38,643 $310 $1,482 ($188) 0.8% -0.5% 6.0%

1984 305,116 $43,825 $41,674 $2,152 $1,540 $825 4.9% 1.9% 9.9%

1985 336,403 $46,664 $45,238 $1,426 $1,588 $863 3.1% 1.8% 9.6%

1986 366,546 $50,525 $49,202 $1,323 $1,693 ($235) 2.6% -0.5% 4.9%

1987 404,471 $56,986 $54,517 $2,469 $1,695 $593 4.3% 1.0% 7.2%

1988 423,302 $63,749 $60,312 $3,437 $1,846 $1,686 5.4% 2.6% 10.8%

1989 432,714 $69,316 $67,505 $1,811 $1,944 $128 2.6% 0.2% 6.3%

1990 457,926 $76,142 $78,054 ($1,912) $1,978 ($3,921) -2.5% -5.1% -6.0%

1991 447,955 $75,158 $76,943 ($1,785) $1,777 ($1,940) -2.4% -2.6% -0.5%

1992 478,554 $78,140 $80,585 ($2,444) $1,743 ($4,791) -3.1% -6.1% -9.3%

1993 489,684 $84,559 $83,121 $1,438 $2,027 ($2,136) 1.7% -2.5% -0.4%

1994 519,382 $88,313 $85,600 $2,713 $2,347 ($344) 3.1% -0.4% 5.2%

1995 540,656 $94,578 $88,718 $5,860 $2,424 $2,314 6.2% 2.4% 11.9%

1996 578,663 $101,938 $95,729 $6,209 $1,981 $2,804 6.1% 2.8% 11.5%

1997 605,434 $109,535 $100,924 $8,611 $1,749 $5,195 7.9% 4.7% 14.9%

Notes: Federal Express began reporting as a section 401 carrier in 1986 and is included in 1986 and later years.

Excludes fresh start accounting extraordinary gains of Continental and Trans World in 1993.

Source: References (33,34).
14-70

Section 14.0 - Economic Profile

Table 14-16

Airline Operating Costs, Selected Components, 1982 - 1997

Year 100) Rate Expenses 100) Rate Expenses 100) Rate Expenses 100) Rate Expenses 100) Rate Expenses 100) Rate Expenses

Labor Fuel Aircraft Fleet (a) Interest Insurance Maintenance Material

Cost Cost Cost Cost Cost Cost

Index Index Index Index Index Index

(1982= Growth % Op. (1982= Growth % Op. (1982= Growth % Op. (1982= Growth % Op. (1982= Growth % Op. (1982= Growth % Op.

1982 100.0 — 34.6% 100.0 — 27.5% 100.0 — 5.6% 100.0 — 4.0% 100.0 — 0.4% 100.0 — 2.0%

1983 107.7 7.7% 35.5% 88.3 -11.7% 24.7% 107.5 7.5% 6.1% 99.0 -1.0% 4.1% 95.7 -4.3% 0.4% 101.7 1.7% 2.1%

1984 108.4 0.6% 33.9% 84.6 -4.2% 24.0% 114.9 6.9% 6.4% 106.3 7.4% 3.9% 109.3 14.2% 0.5% 108.2 6.4% 2.3%

1985 110.6 2.0% 33.8% 79.6 -5.9% 22.3% 123.7 7.7% 6.8% 98.0 -7.8% 3.5% 155.3 42.1% 0.6% 119.9 10.8% 2.5%

1986 108.1 -2.3% 35.8% 55.5 -30.3% 15.5% 127.8 3.3% 7.4% 91.8 -6.3% 3.5% 212.0 36.5% 0.9% 147.7 23.2% 3.2%

1987 110.8 2.5% 34.7% 55.4 -0.2% 15.0% 135.1 5.7% 7.4% 88.7 -3.4% 3.2% 201.8 -4.8% 0.8% 153.1 3.7% 3.2%

1988 113.9 2.8% 34.2% 53.0 -4.3% 13.5% 146.9 8.7% 7.9% 91.9 3.6% 3.1% 151.7 -24.8% 0.6% 166.4 8.7% 3.3%

1989 117.4 3.1% 33.9% 59.7 12.6% 13.9% 162.2 10.4% 8.0% 99.4 8.2% 2.7% 114.5 -24.5% 0.4% 176.8 6.3% 3.2%

1990 123.0 4.8% 31.5% 77.2 29.3% 17.3% 177.0 9.1% 7.9% 96.0 -3.4% 2.6% 68.2 -40.4% 0.3% 190.5 7.7% 3.4%

1991 130.1 5.8% 32.4% 69.4 -10.1% 14.5% 187.1 5.7% 8.5% 81.4 -15.2% 2.4% 81.3 19.2% 0.3% 193.2 1.4% 3.3%

1992 136.5 4.9% 32.8% 65.0 -6.3% 13.5% 202.6 8.3% 9.0% 97.3 19.5% 2.2% 109.3 34.4% 0.4% 177.1 -8.3% 3.0%

1993 143.4 5.1% 33.3% 59.7 -8.2% 12.4% 208.0 2.7% 9.2% 81.2 -16.5% 2.6% 139.4 27.5% 0.5% 166.2 -6.2% 2.9%

1994 148.5 3.6% 34.1% 54.4 -8.9% 10.7% 217.5 4.6% 9.5% 87.6 7.9% 2.8% 110.8 -20.5% 0.7% 157.2 -5.4% 2.6%

1995 155.5 4.7% 34.4% 55.3 1.7% 11.5% 222.8 2.4% 9.5% 93.5 6.7% 3.0% 111.6 0.7% 0.7% 153.4 -2.4% 2.7%

1996 159.5 2.6% 33.6% 64.6 16.8% 13.0% 230.0 3.2% 9.6% 86.9 -7.1% 2.2% 111.5 -0.1% 0.7% 169.4 10.4% 2.9%

1997 162.4 1.8% 33.9% 62.7 -2.9% 12.5% 224.1 -2.6% 9.0% 72.1 -17.0% 1.8% 95.4 -14.4% 0.6% 191.2 12.9% 3.2%

(a) Passenger airlines only; includes lease, aircraft, and engine rentals, depreciation, and amortization.
14-71

Section 14.0 - Economic Profile

Table 14-16 (Continued) 

Year 100) Rate Expenses 100) Rate Expenses 100) Rate Expenses 100) Rate Expenses 100) Rate Expenses 100) Rate

Landing Fees Traffic Commission Communications Advertising & Promotion Passenger Meals Index

Composite Cost

Cost Cost Cost Cost Cost Cost 

Index Index Index Index Index Index 

(1982= Growth % Op. (1982= Growth % Op. (1982= Growth % Op. (1982= Growth % Op. (1982= Growth % Op. (1982 = Growth

1982 100.0 — 1.7% 100.0 — 5.9% 100.0 — 1.5% 100.0 — 2.2% 100.0 — 2.9% 100.0 —

1983 99.6 -0.4% 1.7% 104.4 4.4% 6.5% 98.7 -1.3% 1.5% 99.6 -0.4% 2.3% 101.4 1.4% 3.1% 101.1 1.1%

1984 101.0 1.4% 1.7% 113.9 9.1% 7.1% 98.4 -0.3% 1.5% 97.9 -1.7% 2.3% 104.7 3.3% 3.2% 102.5 1.4%

1985 99.9 -1.1% 1.6% 112.9 -0.9% 7.3% 96.6 -1.8% 1.6% 96.2 -1.7% 2.3% 98.9 -5.5% 3.2% 102.8 0.3%

1986 108.8 8.9% 1.8% 117.7 4.3% 8.1% 105.2 8.9% 1.8% 103.6 7.7% 2.5% 99.4 0.5% 3.4% 99.6 -3.1%

1987 117.7 8.2% 1.9% 126.3 7.3% 8.6% 98.2 -6.7% 1.6% 91.0 -12.2% 2.2% 102.5 3.1% 3.4% 101.9 2.3%

1988 124.8 6.0% 1.9% 145.4 15.1% 9.5% 109.0 11.0% 1.7% 97.1 6.7% 2.2% 108.6 6.0% 3.5% 105.9 3.9%

1989 130.5 4.6% 1.8% 157.7 8.5% 9.5% 111.8 2.6% 1.6% 103.2 6.3% 2.2% 118.8 9.4% 3.5% 112.3 6.0%

1990 139.0 6.5% 1.8% 169.2 7.3% 9.4% 111.2 -0.5% 1.4% 97.8 -5.2% 2.0% 128.4 8.1% 3.5% 122.6 9.2%

1991 153.4 10.4% 1.9% 188.1 11.2% 10.4% 116.6 4.9% 1.4% 89.9 -8.1% 1.8% 139.0 8.3% 3.8% 126.2 2.9%

1992 168.4 9.8% 2.1% 184.9 -1.7% 10.4% 124.5 6.8% 1.5% 81.1 -9.8% 1.7% 140.5 1.1% 3.9% 128.7 2.0%

1993 170.1 1.0% 2.1% 193.0 4.4% 10.9% 120.0 -3.6% 1.5% 72.4 -10.7% 1.5% 128.5 -8.5% 3.6% 130.5 1.4%

1994 171.6 0.9% 2.0% 163.3 -15.4% 9.6% 118.2 -1.5% 1.5% 69.7 -3.7% 1.5% 120.6 -6.1% 3.5% 129.9 -0.5%

1995 176.6 2.9% 2.2% 139.4 -14.6% 8.5% 116.0 -1.9% 1.5% 63.6 -8.8% 1.5% 110.9 -8.0% 3.3% 131.4 1.2%

1996 178.3 1.0% 2.1% 130.8 -6.2% 7.9% 114.8 -1.0% 1.5% 58.4 -8.2% 1.3% 104.0 -6.2% 3.1% 136.8 4.1%

1997 183.2 2.7% 2.0% 127.0 -2.9% 7.7% 110.4 -3.8% 1.4% 54.6 -6.5% 1.3% 102.9 -1.1% 3.1% 137.7 0.7%

Source: Reference (39).
14-72

Section 14.0 - Economic Profile

Table 14-17

Estimated Deicing Costs and Weather Conditions at 5 Selected Airports

Airport and Airport Characteristics Season Degree Days Days < 32E F (inches) Departures Deicing Cost per Departure

Deicing Heating Snowfall Season Reported Deicing Cost

Deicing Reported

Airport A

Northern Tier 1996-97 7,966 165 73.6 88,964 $26,304,455 $296

241,436 departures, 1998 1997-98 6,536 105 50.3 90,334 $27,047,433 $299

11 Major Carriers 1998-99 6,599 91 56.5 60,670 $21,507,999 $355

Operational Hub

Airport B

Northeastern Tier 1996-97 4,468 28 12.9 69,253 $5,843,691 $84

234,732 departures, 1998 1997-98 3,989 7 0.8 76,410 $7,986,294 $105

7 Major Carriers 1998-99 4,110 25 12.5 81,037 $18,871,331 $233

Operational Hub

Airport C

Semi-desert Climate 1996-97 1,545 5 0 25,518 $166,211 $7

136,673 departures, 1998 1997-98 1,527 0 0 23,272 $148,712 $6

9 Major Carriers 1998-99 1,162 2 0 22,979 $182,253 $8

Not an Operational Hub

Airport D

Southeastern Tier 1996-97 4,109 27 5.3 30,111 $16,597,728 $551

86,002 departures, 1998 1997-98 3,850 19 22.8 26,424 $14,319,099 $542

8 Passenger/2 Cargo Airline 1998-99 3,580 27 13.3 21,202 $13,590,916 $641

Cargo Operational Hub

Airport E

Western Arid Climate 1996-97 4,798 34 63.3 56,575 NA NA

182,667 departures, 1998 1997-98 5,060 37 65.2 54,949 $14,876,599 $271

8 Passenger Airlines 1998-99 5,027 36 31.2 52,855 $7,086,810 $134

Operational Hub

Source: Reference (41).
14-73

Section 14.0 - Economic Profile

Table 14-18

National Estimate of Total Deicing Costs at US Airports, 1997 - 1998

Deicing Season HDD Days <32E F Snowfall Average (a) Total Op. Costs of Op. Costs Net Profits Net Profits

Deicing Cost Based on: Deicing Cost Characteristics 

Deicing as % Deicing as % of

1996-97 $548,974,570 $537,591,582 $411,725,552 $543,283,076 $95,729,000,000 0.57% $2,804,000,000 19.38%

1997-98 $522,624,773 $437,407,901 $390,349,428 $480,016,337 $100,982,000,000 0.48% $5,170,000,000 9.28%

1998-99 $506,479,210 $482,485,870 $415,862,888 $494,482,540 $104,034,000,000 0.48% $4,894,000,000 10.10%

(a)Average for HDD and Days < 32E F; snowfall excluded from the estimate because zero snowfall implies zero deicing costs,

yet airlines do incur deicing costs even with zero snowfall.

Source: Reference (41).
Section 15.0 - Glossary

15-1

15.0 GLOSSARY

AAAE - American Association of Airport Executives.

ACAIS - Air Carrier Activity Information System database.

ACI - NA - Airports Council International - North America.

Acute Exposure - Exposure to a chemical for short amount of time relative to the test species

lifespan. It is often contrasted with chronic exposure.

Additive - A component of aircraft deicing/anti-icing fluids. Chemical additives along with

ethylene glycol or propylene glycol are necessary to meet various performance standards. 

Additives can include flame retardants and corrosion inhibitors, surfactants, dyes, pH buffers, and

1,4-dioxane.

ADF-Contaminated Wastewater -Wastewater, runoff, or storm water that has come in contact

with or contains propylene and/or ethylene glycol-based deicing/anti-icing fluids.

Air Carrier - Airlines holding a certificate issued under section 401 of the Federal Aviation Act

of 1958 that operate aircraft designed to have a maximum seating capacity of more than 60 seats

or a maximum payload capacity of more than 18,000 pounds, or conduct international operations. 

The four types of air carriers are: majors, nationals, large regionals, and medium regionals.

Aircraft Deicing/Anti-icing Fluid (ADF) - Fluids that are applied to aircraft surfaces to remove

and/or prevent snow and ice accumulation. They must be approved by the Society of Automotive

Engineers (SAE) and typically contain either ethylene glycol or propylene glycol, together with a

suite of chemical additives to meet various performance standards. There are three types of ADFs

currently in use in the U.S.: Type I, Type II, and Type IV. Type I is a deicing fluid and Types II

and IV are anti-icing fluids. ADFs are applied to ensure that the freezing point of any water on

aircraft remains at a temperature not greater than 20EF below the ambient air or aircraft surface

temperature, whichever is lower (FAA Advisory Circular No. 20-117). All deicing fluids must

lower the freezing point of water to -18EF or lower when applied. 

Aircraft Site Identification Database - A database that contains information for 3,957 facilities

that potentially perform aircraft exterior cleaning and/or aircraft or pavement deicing/anti-icing

operations. 

Airline - A business defined by the type of service it offers, annual revenues, and the type of

aircraft used. All federal safety requirements are pegged to aircraft size.

Airport Improvement Program (AIP) - A program administered by the FAA whereby federal

funds are dispersed for projects that will maintain current airport infrastructure and increase the

capacity of facilities in order to commodate growing passenger and cargo traffic. 
Section 15.0 - Glossary

15-2

Airport Matrix - An EPA database designed for this study containing current information on all

aspects of airfield pavement and aircraft deicing for the airports for which detailed information

were obtained from EPA site visits or questionnaires.

Air Taxi - An aircraft designed to have a maximum seating capacity of 60 seats or less or a

maximum payload capacity of 18,000 pounds or less carrying passengers or cargo for hire or

compensation. (See Air Carrier.)

AMIL - Anti-Icing Materials Laboratory located at the University of Quebec, Chicoutimi,

Canada.

AMS - Aerospace Material Specification.

Anti-icing Operations - The prevention of the accumulation of frost, snow, or ice on aircraft or

pavement. These operations are typically discussed with deicing operations. There are two types

of deicing/anti-icing operations: dry-weather and wet-weather.

ARP - Aerospace Recommended Practice.

ATA - Air Transport Association.

Biochemical Oxygen Demand (BOD ) - Five-day biochemical oxygen demand. A measure of 5

biochemical decomposition of organic matter in a water sample. It is determined by measuring

the dissolved oxygen consumed by microorganisms to oxidize the organic matter in a water

sample under standard laboratory conditions of five days and 20EC (see Method 405.1). BOD is 5

not related to the oxygen requirements in chemical combustion.

BTS - Bureau of Transportation Safety.

Calcium Magnesium Acetate (CMA) - A solid runway deicer/anti-icer.

Canadian Environmental Protection Act (CEPA) - A Canadian federal statute that provides

the authority for the establishment of the Part IV Glycol Guidelines in 1994 which included a

voluntary guideline recommending discharge limitations for glycol at Canadian federal airports.

Canadian Water Quality Guidelines for Glycol - Established a voluntary guideline in 1997

recommending safe environmental levels from the discharge of glycols into the environment. 

Carcinogen - A chemical capable of inducing cancer.

Cargo - Anything other than passengers, carried for hire, including both mail and freight.

Cargo Carrier - Airlines that primarily carry cargo using aircraft called “freighters.” Freighters

are essentially passenger aircraft with all or nearly all of the passenger seats removed.
Section 15.0 - Glossary

15-3

CFR - Code of Federal Regulations, published by the U.S. Government Printing Office. A

codification of the general and permanent rules published by the Federal Register by the Executive

departments and agencies of the federal government.

Chemical Oxygen Demand (COD) - A nonconventional, bulk parameter that measures the

oxygen-consuming capacity of refractory organic and inorganic matter present in water or

wastewater. COD is expressed as the amount of oxygen consumed from a chemical oxidant in a

specific test (see Methods 410.1 through 401.4).

Chronic Exposure - Exposure to a chemical for a long duration, relative to the test species

lifespan. It is often contrasted with acute exposure.

Civil Landing Area - FAA-approved landing site for aircraft, helicopters, or seaplanes. Civil

landing areas are not associated with miliary areas.

Commercial Service Airports - Public airports receiving scheduled passenger service and having

2,500 or more enplaned passengers per year. There are 538 commercial service airports in the

U.S.

CERCLA - Comprehensive Environmental Response, Compensation and Liability Act.

CWA - Clean Water Act. The Federal Water Pollution Control Act Amendments of 1972 (33

U.S.C. 1251 et seq.), as amended, inter alia, by the Clean Water Act of 1977 (Public Law 95-217)

and the Water Quality Act of 1987 (Public Law 100-4).

Deicing Operations - The removal of frost, snow, or ice from aircraft or pavement. These

operations are typically discussed with anti-icing operations. There are two types of deicing/antiicing operations: dry-weather and wet-weather.

Developmental Toxicity - The occurrence of adverse effects on the developing organism that

may result from exposure to a chemical prior to conception, during prenatal development, or

postnatally to the time of sexual maturation. Adverse developmental effects may be detected at a

point in the lifespan of the organism.

Direct Discharger - A facility that conveys or may convey untreated or facility-treated process

wastewater or nonprocess wastewater directly into surface waters of the United States, such as

rivers, lakes, or oceans. (See Surface Waters definition.)

Discharge - The conveyance of wastewater to: (1) United States surface waters such as rivers,

lakes, and oceans, or (2) a publicly owned, federally owned, or other treatment works.

DO - Dissolved oxygen. The oxygen freely available in water, vital to fish and other aquatic life

and for the prevention of odors. DO levels are considered a most important indicator of a water

body's ability to support desirable aquatic life (see Methods 350.1 and 350.2).
Section 15.0 - Glossary

15-4

Dry-Weather Deicing/Anti-icing - Also referred to as clear-ice deicing, may be performed

whenever ambient temperatures are cold enough to form ice on aircraft wings (below 55EF). 

Dry-weather deicing/anti-icing is also used to defrost windshields and wingtips on commuter

planes. May also be performed as necessary on some types of aircraft whose fuel tanks become

super-cooled during high altitude flight, resulting in ice formation at lower altitudes and after

landing. Dry-weather deicing is usually conducted throughout the entire deicing/anti-icing season.

EC - Environment Canada.

EC50 - The median effective concentration. The concentration of a substance that causes a

specified effect (generally sublethal rather than acutely lethal) in 50% of the test organisms.

Effluent - Wastewater discharges. 

Effluent Limitation - Any restriction, including schedules of compliance, established by a state

or the Administrator on quantities, rates, and concentrations of chemical, physical, biological, and

other constituents that are discharged from point sources into navigable waters, the waters of the

contiguous zone, or the ocean. (CWA Sections 301(b) and 304(b).)

Enplanements - The number of passengers boarding a flight.

EPA - The U.S. Environmental Protection Agency.

Ethylene Glycol - A commonly used freezing point depressant in aircraft deicing/anti-icing fluids

and pavement deicers. 

FAA - Federal Aviation Administration.

FDA - Food and Drug Administration.

FIFRA - Federal Insecticide, Fungicide, Rodenticide Act.

Fixed-Based Operators (FBOs) - Companies that have contracts with the airport

authority/airlines to conduct business operations on airport property.

FR - Federal Register, published by the U.S. Government Printing Office, Washington, D.C. A

publication making available to the public regulations and legal notices issued by federal agencies.

Freight - All air cargo excluding mail.

GAO - General Accounting Office.

General Aviation (GA) Airports - Airports that do not receive commercial service, have at least

10 locally owned aircraft, and are at least 20 miles from the nearest NPIAS airport.
Section 15.0 - Glossary

15-5

General Aviation Operations - Takeoffs and landings of all civil aircraft, except those classified

as air carriers or air taxis. 

Glycol-Contaminated Wastewater - Wastewater, runoff, or storm water that has come in

contact with or contains propylene and/or ethylene glycol-based deicing/anti-icing fluids.

GRAS - Generally Recognized as Safe.

HAP - Hazardous Air Pollutant.

Hexane Extractable Material (HEM) - A method-defined parameter that measures the presence

of relatively nonvolatile hydrocarbons, vegetable oils, animal fats, waxes, soaps, greases, and

related materials that are extractable in the solvent n-hexane (see Method 1664). HEM has

replaced the freon-based oil and grease method.

Holdover Time - The period of time when ice or snow is prevented from adhering to the surface

of an aircraft (i.e., the amount of time between application and takeoff). 

Hubs - A term used by the FAA to identify very busy commercial service airports.

Immunological Toxicity - The occurrence of adverse health effects on the immune system that

may result from exposure to chemicals.

Indirect Discharger - A facility that discharges or may discharge pollutants into a publicly owned

treatment works (POTW).

ISO - International Standards Organization.

Isopropanol - A freezing point depressant that may be used in aircraft or pavement deicing/antiicing fluids.

Large Regional Carrier - A type of air carrier with annual operating revenues between $20

million and $100 million.

LC50 - Concentration at which exposure for specific length of time is expected to cause death in

50% of a defined experimental population.

LD50 - The dose of a chemical that has been calculated to cause death in 50% of a defined

experimental population.

Lethal Dose - The lowest does of a chemical introduced by a route other than inhalation that is

expected to have caused death in humans or animals. 
Section 15.0 - Glossary

15-6

Lowest-Observed-Adverse-Effect Level (LOAEL) - The lowest dose of chemical in a study, or

a group of studies, that produces statistically or biologically significant increases in frequency or

severity of adverse effects between the exposed population and its appropriate control.

Major Carrier - A type of air carrier with annual operating revenues greater than $1 billion.

MCL - Maximum Concentration Level.

MEBT - 5-methyl-1H-benzotriazole or TTZ or tolyltriazole.

Medium Regional Carrier - A type of air carrier with annual operating revenues between $0 and

$20 million.

Miliary Operations - All classes of military operations at FAA air traffic facilities.

MIL-SPEC - Military performance specifications for aircraft and pavement deicers/anti-icers. 

Similar to SAE performance specifications.

Mutagen - A substance that causes mutations (i.e., a change in the genetic material in a body

cell). 

NASA - National Aeronautics and Space Administration.

National Carrier - A type of air carrier with annual operating revenues between $100 million and

$1 billion.

National Plan of Integrated Airport Systems (NPIAS) - A plan submitted to Congress in

accordance with Section 47103 of Title 49 of the United States Code. Identifies airports that are

important to national transportation, and, therefore, eligible to receive grants under the Airport

Improvement Program (AIP). Does not apply to stand-alone military airports.

NOI - Notice of Intent.

Nondetect Value - A concentration-based measurement reported below the sample-specific

detection limit that can reliably be measured by the analytical method for the pollutant.

No-Observed-Adverse-Effect Level (NOAEL) - The dose of chemical at which there were no

statistically or biologically significant increases in frequency or severity of adverse effects seen

between the exposed population and its appropriate control. Effects may be produced at this

dose, but they are not considered adverse.

Nonprimary Commercial Service Airports - Commercial service airports with less than 10,000

annual enplanements. There are 125 nonprimary commercial airports in the U.S.
Section 15.0 - Glossary

15-7

NPDES - The National Pollutant Discharge Elimination System authorized under Sec. 402 of the

CWA. NPDES requires permits for discharge of pollutants from any point source into waters of

the United States.

NRDC - Natural Resources Defense Council.

Octanol-Water Partition Coefficient (Kow) - The equilibrium ratio of the concentrations of a

chemical in n-octanol and water, in dilute solution.

OECD - Organization for Economic Cooperation and Development.

Operational Hub - See Section 14.0 - but used to describe airlines main airport for connections

in the hub & spoke system.

Pollution Prevention - The use of materials, processes, or practices that reduce or eliminate the

creation of pollutants or wastes. It includes practices that reduce the use of hazardous and

nonhazardous materials, energy, water, or other resources, as well as those practices that protect

natural resources through conservation or more efficient use. Pollution prevention consists of

source reduction, in-process recycle and reuse, and water conservation practices.

Potassium Acetate - A liquid runway deicer. 

POTW - Publicly owned treatment works, as defined at 40 CFR 403.3(o).

Primary Commercial Airports - Commercial service airports with more than 10,000 annual

enplanements. There are 413 primary commercial airports in the U.S.

Propylene Glycol - A commonly used freezing point depressant in aircraft deicing/anti-icing

fluids.

RAA - Regional Airline Association.

Regional Carriers - Airlines whose services are generally limited to a single region of the country

and have annual revenues of less than $100 million. These carriers are divided into three groups:

large, medium, and small.

Reliever Airports - Included in the NPIAS. High-capacity general aviation airports in major

metropolitan areas. There are 334 reliever airports in the U.S.

Reproductive Toxicity - The occurrence of adverse effects on the reproductive system that may

result from exposure to a chemical.

RWIS - Road/Runway Weather Information System.
Section 15.0 - Glossary

15-8

Screener Questionnaire - The EPA 1993 Screener Questionnaire for the Transportation

Equipment Cleaning Industry.

SIC - Standard industrial classification. A numerical categorization system used by the U.S.

Department of Commerce to catalogue economic activity. SIC codes refer to the products, or

group of products, produced or distributed, or to services rendered by an operating establishment. 

SIC codes are used to group establishments by the economic activities in which they are engaged. 

SIC codes often denote a facility's primary, secondary, tertiary, etc. economic activities.

Silica Gel-Treated Hexane Extractable Material (SGT-HEM) - A method-defined parameter

that measures the presence of mineral oils that are extractable in the solvent n-hexane and not

adsorbed by silica gel (see Method 1664). SGT-HEM is also referred to as nonpolar material.

Small Regional Carrier - The largest segment of the regional airline business and mostly operate

planes that have less than 30 seats. They are often called “commuters.” There is no revenue cutoff for this group.

SMI - Scientific Material International.

Society of Automotive Engineers (SAE) - A professional organization dedicated to improving

safety and promoting new technologies in all sectors of the transportation industry through the

development of engineering standards. The SAE Aerospace Council is responsible for developing

standards for the aircraft industry and is organized into technical committees, each with its own

area of specialization. The committee responsible for aircraft deicing and anti-icing issues is the

G-12 Committee. 

Sodium Acetate - A solid runway deicer.

Sodium Formate - A runway deicer typically applied in a pellet form and mixed with corrosion

inhibitors to meet performance standards.

Storm Water - Storm water runoff, snow-melt runoff, and surface runoff and drainage.

Surface Waters - Waters including, but not limited to, oceans and all interstate and intrastate

lakes, rivers, streams, mudflats, sand flats, wetlands, sloughs, prairie potholes, wet meadows,

playa lakes, and natural ponds.

TECI - Transportation Equipment Cleaning Industry.

Teratogen - A chemical that causes structural defects that affect the development of an organism.

TMDL - Total Maximum Daily Load.
Section 15.0 - Glossary

15-9

TOC - Total organic carbon. A measure of total organic content of wastewater. Unlike five-day

biochemical oxygen demand (BOD ) or chemical oxygen demand (COD), TOC is independent of 5

the oxidation state of the organic matter and does not measure other organically bound elements,

such as nitrogen and hydrogen, and inorganics that can contribute to the oxygen demand

measured by BOD and COD. TOC methods utilize heat and oxygen, ultraviolet irradiation, 5

chemical oxidants, or combinations of these oxidants to convert organic carbon to carbon dioxide

(CO ). The CO is then measured by various methods. 2 2

TOD - Total oxygen demand. A theoretical measure of the amount of oxygen required to break

down a substance to its simplest parts. The COD of a substance may be used as a surrogate for

the TOD.

TRI - Toxics Release Inventory.

TSCA - Toxic Substances Control Act.

TSS - Total suspended solids. A measure of the amount of particulate matter that is suspended in

a water sample. The measure is obtained by filtering a water sample of known volume. The

particulate material retained on the filter is then dried and weighed, see Method 160.2.

TTZ - Tolyltriazole or 5-methyl-1H-benzotriazole. A common additive in aircraft deicing/antiicing fluids that is used as a corrosion inhibitor and flame retardant.

Type I ADFs - The most commonly used fluid. They are primarily used for aircraft deicing. 

They have the shortest holdover time of any type of fluid. Type I ADFs typically contain either

ethylene glycol or propylene glycol, water, and additives.

Type II ADFs - Primarily used for aircraft anti-icing. They have a holdover time between Type I

and Type IV fluids. They are typically composed of either ethylene glycol or propylene glycol, a

small amount of thickener, water, and additives. 

Type III ADFs - Designed for aircraft anti-icing for smaller, commuter aircraft. They have a

holdover time between Type I and Type II fluids; however, they are believed to be obsolete.

Type IV ADFs - Primarily used for aircraft anti-icing. They have the longest holdover time of

any type of fluid. They are typically composed of either ethylene glycol or propylene glycol, a

small amount of thickener, water, and additives. 

UCAR - A runway deicer manufactured by Union Carbide that contains urea, ethylene glycol, and

water.

Urea - A runway deicer that is typically applied to pavement and runway areas in granular form. 

U.S.C. - The United States Code.
Section 15.0 - Glossary

15-10

USGS - United States Geological Survey.

VOCs - Volatile organic compounds. Any organic compound that participates in atmospheric

photochemical reactions except those designated by EPA as having negligible photochemical

reactivity.

Wet-Weather Deicing/Anti-icing - Occurs during storm events that include precipitation such as

snow, sleet, or freezing rain.

WSDDM - Weather Support to Deicing Decision Making.
Appendix A

SELECT U.S. AIRPORT LOCATIONS
A-1

Appendix A

Select U.S. Airport Locations

Airport

Code Airport Name Location 

ILN Airborne Air Park Wilmington, OH

ALB Albany International Albany, NY

ANC Anchorage International Anchorage, AK

BWI Baltimore/Washington International Baltimore, MD

BIL Billings Logan International Billings, MT

BDL Bradley International Windsor Locks, CT (services Hartford, CT/

Springfield, MA

BUF Buffalo International Buffalo, NY

ORD Chicago O’Hare International Chicago, IL

CVG Cincinnati/Northern Kentucky International Covington/Cincinnati, KY/OH

CLE Cleveland Hopkins International Cleveland, OH

DFW Dallas/Ft. Worth International Dallas-Ft. Worth, TX

DAY Dayton International Dayton, OH

DIA Denver International Denver, CO

DSM Des Moines International Des Moines, IA

DTW Detroit Metropolitan Wayne Country Detroit, MI

DLH Duluth International Duluth, MN

MKE General Mitchell International Milwaukee, WI

RFD Greater Rockford Rockford, IL

MCI Kansas City International Kansas City, MO

MEI Key Field (Meridian) Meridian, MS

LGA LaGuardia New York, NY

STL Lambert-St. Louis International St. Louis, MO

BOS Logan International Boston, MA

SDF Louisville International-Standiford Field Louisville, KY

MSP Minneapolis-St. Paul International Minneapolis-St. Paul, MN

BNA Nashville International Nashville, TN

EWR Newark International Newark, NJ

PIT Pittsburgh International Pittsburgh, PA

PDX Portland International Portland, OR

RIC Richmond International Richmond, VA

DCA Ronald Reagan Washington National Arlington, VA (services Washington, DC)
Appendix A (Continued)

Airport

Code Airport Name Location 

A-2

SEA Seattle-Tacoma International Seattle, WA

SLC Salt Lake City International Salt Lake City, UT

SYR Syracuse Hancock International Syracuse, NY

PVD T.F. Green Providence, RI

ITH Tomkins County Ithaca, NY

HTS Tri-State (Huntington) Huntington, WV

HPN Westchester County White Plains, NY

IAD Washington Dulles International Chantilly, VA (services Washington DC)
Appendix B

MEAN ANNUAL SNOWFALL (THROUGH 1995)

FOR SELECT U.S. CITIES
B-1

Appendix B

Mean Annual Snowfall (Through 1995) for Select U.S. Cities

City, State Mean Annual Snowfall (in.)

VALDEZ, AK 325.8

MT. WASHINGTON, NH 253.9

YAKUTAT, AK 197.6

MARQUETTE, MI 130.6

SAULT STE. MARIE, MI 117.1

TALKEETNA, AK 115.0

SYRACUSE, NY 114.7

CARIBOU, ME 110.7

LANDER, WY 102.2

JUNEAU, AK 100.7

FLAGSTAFF, AZ 100.3

MUSKEGON, MI 97.9

MCGRATH, AK 94.2

BUFFALO, NY 91.8

ROCHESTER, NY 90.3

ERIE, PA. 86.5

ALPENA, MI 85.7

BINGHAMTON, NY 82.8

BETTLES,AK 82.5

CASPER, WY 79.1

DULUTH, MN 78.9

BURLINGTON, VT 78.0

KODIAK, AK 77.4

ELKINS, WV 76.7

HOUGHTON LAKE, MI 75.0

GRAND RAPIDS, MI 71.8

SHERIDAN, WY 71.7

SOUTH BEND, IN 70.9

PORTLAND, ME 70.8

ANCHORAGE, AK 70.0

FAIRBANKS, AK 69.5

WORCESTER, MA 67.6
Appendix B (Continued)

City, State Mean Annual Snowfall (in.)

B-2

INTERNATIONAL FALLS, MN 64.6

KALISPELL, MT 63.9

ALBANY, NY 63.8

CONCORD, NH 63.5

COLD BAY,AK 60.8

DENVER, CO 60.3

BECKLEY, WV 60.0

BLUE HILL, MA 59.5

NOME, AK 58.8

GREAT FALLS, MT 58.4

HOMER, AK 57.7

SALT LAKE CITY, UT 57.7

ST. PAUL ISLAND, AK 56.7

BILLINGS, MT 56.3

YOUNGSTOWN, OH 56.1

CLEVELAND, OH 55.7

CHEYENNE, WY 55.4

GULKANA,AK 50.7

MINNEAPOLIS-ST.PAUL, MN 49.5

SPOKANE, WA 49.5

BETHEL, AK 49.4

LANSING, MI 49.0

ANNETTE, AK 48.9

ELY, NV 48.9

ROCHESTER, MN 48.6

AVOCA, PA 48.1

HARTFORD, CT 47.9

KOTZEBUE, AK 47.6

AKRON, OH 47.4

MILWAUKEE, WI 47.2

HELENA, MT 47.0

GREEN BAY, WI 46.7

KING SALMON, AK 46.1

MISSOULA, MT 45.5
Appendix B (Continued)

City, State Mean Annual Snowfall (in.)

B-3

FLINT, MI 45.2

SAINT CLOUD, MN 44.9

MADISON, WI 43.9

BIG DELTA,AK 43.8

DUBUQUE,IA 43.6

PITTSBURGH, PA 43.5

POCATELLO, ID 42.7

BISMARCK, ND 42.7

LA CROSSE, WI 42.5

COLORADO SPRINGS, CO 42.3

MANSFIELD, OH 42.1

WILLIAMSPORT, PA 41.9

BOSTON, MA 41.7

SCOTTSBLUFF, NE 41.5

DETROIT, MI 41.3

BURNS,OR 41.3

HURON, SD 40.1

SIOUX FALLS, SD 40.1

WILLISTON, ND 39.5

RAPID CITY, SD 39.4

FARGO, ND 38.9

CHICAGO,IL 38.2

GOODLAND, KS 38.2

UNALAKLEET, AK 38.0

ELKO, NV 37.6

TOLEDO, OH 37.0

ABERDEEN, SD 36.5

ROCKFORD, IL 35.9

PROVIDENCE, RI 35.9

MIDDLETOWN/HARRISBURG INTL APT 35.0

ALAMOSA, CO 33.9

PUEBLO, CO 33.5

VALENTINE, NE 33.5

DES MOINES, IA 33.3
Appendix B (Continued)

City, State Mean Annual Snowfall (in.)

B-4

CHARLESTON, WV 33.1

FORT WAYNE, IN 32.8

WATERLOO, IA 32.3

ALLENTOWN, PA 32.1

SIOUX CITY, IA 31.7

OMAHA (NORTH), NE 31.2

GRAND ISLAND, NE 30.5

NORFOLK, NE 30.5

MOLINE, IL 30.4

NORTH PLATTE, NE 30.4

OMAHA EPPLEY AP, NE 29.8

NEW YORK C.PARK, NY 28.3

BARROW, AK 28.2

COLUMBUS, OH 27.9

GLASGOW, MT 27.7

DAYTON, OH 27.7

NEWARK, NJ 27.5

LINCOLN, NE 26.8

HUNTINGTON, WV 26.0

NEW YORK (LAGUARDIA AP), NY 25.8

BRIDGEPORT, CT 25.5

PEORIA, IL 24.8

GRAND JUNCTION, CO 24.7

RENO, NV 24.4

YAKIMA, WA 23.6

WINNEMUCCA, NV 23.5

GREATER CINCINNATI AP 23.4

SPRINGFIELD, IL 23.1

COLUMBIA, MO 23.1

INDIANAPOLIS, IN 22.9

NEW YORK (JFK AP), NY 22.9

JACKSON, KY 22.8

ROANOKE, VA 22.5

WASHINGTON DULLES AP, D.C. 22.3
Appendix B (Continued)

City, State Mean Annual Snowfall (in.)

B-5

CLAYTON, NM 22.0

CONCORDIA, KS 21.6

TOPEKA, KS 20.8

PHILADELPHIA, PA 20.8

BOISE, ID 20.7

ISLIP, NY 20.5

BALTIMORE, MD 20.4

WILMINGTON, DE 20.3

DODGE CITY, KS 19.9

KANSAS CITY, MO 19.9

ST. LOUIS, MO 19.5

PENDLETON, OR 17.7

LYNCHBURG, VA 17.7

SPRINGFIELD, MO 17.2

OLYMPIA, WA 16.8

WASHINGTON NAT'L AP, D.C. 16.4

LOUISVILLE, KY 16.1

LEWISTON, ID 15.8

LEXINGTON, KY 15.8

WICHITA, KS 15.7

ATLANTIC CITY AP, NJ 15.7

BRISTOL-JHNSN CTY-KNGSPRT,TN 15.4

AMARILLO, TX 15.0

ASHEVILLE, NC 14.9

RICHMOND, VA 13.7

EVANSVILLE, IN 13.6

QUILLAYUTE, WA 13.0

KNOXVILLE, TN 11.6

SEATTLE SEA-TAC AP, WA 11.3

ROSWELL, NM 11.1

ALBUQUERQUE, NM 10.8

PADUCAH KY 10.6

WINSLOW, AZ 10.5

NASHVILLE, TN 9.9
Appendix B (Continued)

City, State Mean Annual Snowfall (in.)

B-6

LUBBOCK, TX 9.9

OAK RIDGE,TN 9.5

TULSA, OK 9.4

OKLAHOMA CITY, OK 9.2

GREENSBORO-WNSTN-SALM-HGHPT,NC 8.5

WALLOPS ISLAND, VA 8.4

BISHOP, CA 8.2

NORFOLK, VA 7.4

MEDFORD, OR 7.2

RALEIGH, NC 6.9

SEATTLE C.O., WA 6.8

SALEM, OR 6.6

PORTLAND, OR 6.5

NORTH LITTLE ROCK, AR 6.3

EUGENE, OR 6.3

FORT SMITH, AR 6.2

GREENVILLE-SPARTANBURG AP, SC 5.9

WICHITA FALLS, TX 5.7

CHARLOTTE, NC 5.4

EL PASO, TX 5.3

LITTLE ROCK, AR 5.1

MEMPHIS, TN 5.1

ABILENE, TX 4.6

ASTORIA, OR 4.3

CHATTANOOGA, TN 4.3

MIDLAND-ODESSA, TX 4.2

REDDING, CA 2.9

TUPELO, MS 2.9

SAN ANGELO, TX 2.9

HUNTSVILLE, AL 2.7

DALLAS-FORT WORTH, TX 2.5

ATHENS, GA 2.4

ATLANTA, GA 2.0

CAPE HATTERAS, NC 1.9
Appendix B (Continued)

City, State Mean Annual Snowfall (in.)

B-7

WILMINGTON, NC 1.9

COLUMBIA, SC 1.7

BIRMINGHAM AP,AL 1.5

SHREVEPORT, LA 1.5

WACO, TX 1.4

TUCSON, AZ 1.2

MERIDIAN, MS 1.2

LAS VEGAS, NV 1.2

AUGUSTA,GA 1.1

MACON, GA 0.9

JACKSON, MS 0.9

AUSTIN, TX 0.9

DEL RIO, TX 0.9

CHARLESTON AP,SC 0.7

SAN ANTONIO, TX 0.7

COLUMBUS, GA 0.5

MOBILE, AL 0.4

MONTGOMERY, AL 0.4

SAVANNAH, GA 0.4

HOUSTON, TX 0.4

LAKE CHARLES, LA 0.3

PORT ARTHUR, TX 0.3

EUREKA, CA. 0.2

PENSACOLA, FL 0.2

BATON ROUGE, LA 0.2

NEW ORLEANS, LA 0.2

FRESNO, CA 0.1

VICTORIA, TX 0.1

SANTA BARBARA, CA 0

FORT MYERS, FL 0

KEY WEST, FL 0

MIAMI, FL 0

HILO, HI 0

HONOLULU,HI 0
Appendix B (Continued)

City, State Mean Annual Snowfall (in.)

B-8

KAHULUI, HI 0

LIHUE, HI 0

GUAM, PC 0

KOROR, PC 0

KWAJALEIN, MARSHALL IS., PC 0

MAJURO, MARSHALL IS, PC 0

PAGO PAGO, AMER SAMOA, PC 0

POHNPEI, CAROLINE IS., PC 0

CHUUK, E. CAROLINE IS., PC 0

WAKE ISLAND, PC 0

YAP, W CAROLINE IS., PC 0

Source: National Oceanic Atmospheric Administration.
Appendix C

CLIMATE CONTOUR MAP OF THE U.S.
C-1
Appendix D

SELECTED FINANCIAL AND SCHEDULED SERVICE TRAFFIC STATISTICS
D-1

U.S. Large Certificated Air Carriers, 1997 - 1998

12 month period ending 6/30/98

Air Carrier Revenues Income (x 1,000) (x 1,000) (x 1,000) (x 1,000) (x 1,000) State Notes [3]

Operating Net ments Miles Seat Miles Ton-miles Ton-miles HQ

Passenger Revenue

Enplane- Passenger Available Passenger Cargo

Majors

Alaska $1,527,189 $105,841 12,548 9,900,889 14,743,618 1,073,610 77,693

America West $1,938,366 $102,971 17,826 15,969,799 23,772,818 1,596,980 113,748

American $16,229,821 $1,017,980 81,192 107,640,234 154,188,327 10,764,023 2,053,551

Continental $6,870,111 $427,490 40,150 47,639,667 66,422,995 4,763,967 737,402

Delta $14,328,259 $1,000,505 104,050 101,056,563 139,995,366 10,105,656 1,744,996

DHL Airways $1,284,853 ($32,962) 0 0 0 0 358,264

Federal Express $13,414,818 $441,887 0 0 0 0 6,518,002

Northwest $9,881,713 $536,386 54,506 72,408,489 97,219,704 7,240,849 2,226,434

Southwest $3,994,409 $376,467 57,286 29,935,657 45,978,282 2,993,566 131,828

Trans World $3,370,128 ($60,897) 24,112 25,510,913 36,025,463 2,551,092 310,055

United $17,329,571 $924,935 84,500 121,683,332 170,943,723 12,168,333 2,972,682

United Parcel $1,842,455 ($22,203) 0 0 0 0 895,094

US Airways $8,494,535 $1,003,208 57,869 41,051,381 56,773,242 4,105,139 349,414

Nationals

Air Transport Int’l $117,749 $8,911 0 0 0 0 0 AR NSS

Air Wisconsin $155,265 $3,917 2,045 645,827 1,025,905 64,583 521 WI

Air Trans [2] $197,217 ($3,407) 2,261 1,494,612 2,487,706 149,461 947 FL

Valuejet $183,424 ($70,179) 2,339 1,203,597 2,392,198 120,396 2,153

Aloha $235,350 $6,526 5,312 734,974 1,112,337 73,498 9,416 HI

American Eagle[3,4] $645,073 $33,198 6,829 1,477,972 2,423,606 147,797 606 TX

Flagship

Simmons

Wings West

American Int’l. $437,568 ($17,166) 0 0 0 0 82,314 MI

American Trans Air $824,896 $28,663 3,776 5,259,538 7,163,577 525,954 0 IN

Arrow $89,363 ($19,941) 0 0 0 0 96,540 FL

Atlantic Southwest $396,451 $57,804 3,876 976,055 1,818,538 97,605 611 GA

Atlas $392,674 $30,782 0 0 0 0 0 NY NSS

Carnival $63,299 ($28,063) 971 1,052,291 1,554,150 105,229 1,525 FL

Challenge Air Cargo $134,928 $2,713 0 0 0 0 215,969 FL

Continental Express [4] $516,630 $50,918 5,261 1,358,487 2,355,329 135,849 536 TX

Continental Micronesia $670,352 ($28,163) 2,432 4,206,328 6,178,542 420,633 134,949 HI

Emery $556,661 ($7,389) 0 0 0 0 0 CA NSS

Evergreen $274,871 ($4,172) 0 0 0 0 538,171 OR

Executive [4] $96,138 $4,142 1,446 276,806 463,382 27,681 10 PR

Frontier $155,474 ($15,226) 1,348 1,104,154 1,945,860 110,415 5,262 CO

Hawaiian $409,838 $2,008 4,934 3,152,308 4,357,865 315,231 56,782 HI
U.S. Large Certificated Air Carriers, 1997 - 1998 (Continued)

12 month period ending 6/30/98

Air Carrier Revenues Income (x 1,000) (x 1,000) (x 1,000) (x 1,000) (x 1,000) State Notes [3]

Operating Net ments Miles Seat Miles Ton-miles Ton-miles HQ

Passenger Revenue

Enplane- Passenger Available Passenger Cargo

D-2

Horizon Air [4] $322,395 $10,688 3,930 980,848 1,590,185 98,085 3,469 WA

Midway $197,415 $13,471 1,538 842,662 1,300,572 84,266 763 NC

Midwest Express $333,483 $30,046 1,747 1,498,079 2,323,706 149,808 18,442 WI

Polar Air Cargo $337,239 ($30,155) 0 0 0 0 1,113,913 CA

Reno $392,027 ($12,791) 5,248 2,830,249 4,428,320 283,025 5,412 NV

Southern Air $124,336 ($31,641) 0 0 0 0 0 OH NSS

Sun Country $245,899 ($4,772) 0 0 0 0 0 MN NSS

Tower $487,212 ($8,876) 1,459 3,920,610 5,162,146 392,061 97,895 NY

Trans States $211,165 $24,990 2,370 480,040 935,877 48,004 0 MO

US Air Shuttle $173,664 $5,987 1,516 302,491 685,793 30,249 294 NY

World $289,588 ($4,359) 0 0 0 0 0 VA NSS

Large Regionals

Amerijet $71,817 $4,033 0 0 0 0 97,520 FL

Champion $53,565 ($26,456) 0 0 0 0 0 MN NSS

Express One $111,552 ($1,910) 0 0 0 0 0 TX NSS

Fine $87,610 ($6,575) 0 0 0 0 0 FL NSS

Florida West $64,267 $2,724 0 0 0 0 65,263 FL

Gemini Air Cargo $95,472 $11,488 0 0 0 0 0 DC NSS

Kitty Hawk $117,667 $7,701 0 0 0 0 0 TX NSS

Kiwi $73,447 ($22,084) 609 558,891 988,784 55,889 914 NJ Chap. 11

Mesaba $303,270 $21,862 3,749 926,228 1,708,509 92,623 279 MN

Miami Air $78,399 $1,278 0 0 0 0 0 FL NSS

North American $60,665 $1,467 0 0 0 0 0 NY NSS

Northern Air $40,918 $4,112 0 0 0 0 17,890 AK

Pan American $38,264 ($20,119) 333 538,284 795,823 53,828 9,615 FL

Reeve $29,827 ($2,230) 57 35,607 83,619 3,561 4,002 AK

Ryan Int’l. $110,568 $4,547 0 0 0 0 0 KS NSS

Spirit $102,661 $3,909 1,088 871,324 1,109,572 87,132 0 MI

Sun Pacific $11,785 $287 0 0 0 0 0 AZ NSS

TransMeridian $29,682 ($2,337) 0 0 0 0 0 GA NSS

UFS $57,689 $1,063 670 106,306 211,065 10,631 0 MO

USA Jet $76,188 $4,700 0 0 0 0 0 MI NSS

Vanguard $84,907 ($17,411) 1,078 674,740 1,088,814 67,474 846 MO

Zantop $12,138 ($1,892) 0 0 0 0 0 MI NSS

Small Regionals

Capital Cargo $16,920 $375 0 0 0 0 0 FL NSS

Casino Express $15,692 ($2,676) 205 201,846 239,369 20,184 0 NV

Custom Air $10,388 ($146) 0 0 0 0 0 FL
U.S. Large Certificated Air Carriers, 1997 - 1998 (Continued)

12 month period ending 6/30/98

Air Carrier Revenues Income (x 1,000) (x 1,000) (x 1,000) (x 1,000) (x 1,000) State Notes [3]

Operating Net ments Miles Seat Miles Ton-miles Ton-miles HQ

Passenger Revenue

Enplane- Passenger Available Passenger Cargo

D-3

Eastwind $22,641 ($8,684) 240 102,118 308,701 10,212 0 NC

Falcon $13,955 $1,265 0 0 0 0 0 FL NSS

Lynden Air Cargo $20,395 ($5,761) 0 0 0 0 6,527 AK

Nations Air $6,724 $299 0 0 0 0 0 GA NSS

Omni $24,955 $1,141 0 OK

Pace $4,914 $256 0 0 0 0 0 NC NSS

Panagra $3,610 ($1,071) 0 0 0 0 0 FL NSS

Pro Air $11,247 ($18,849) 161 73,399 308,727 7,340 0 WA

Renown $8,599 ($1,033) 0 0 0 0 0 CA NSS

Sierra Pacific $6,650 $631 0 0 0 0 0 AZ NSS

Sunworld $7,696 ($914) 19 27,234 57,486 2,723 0 KY PNSS

Tatonduk $7,248 $1,127 NA 453 1,784 45 39 AK

Tradewinds $14,965 ($665) 0 0 0 0 0 NC 6 mos.

Trans Continental $22,719 $1,172 0 0 0 0 0 MI NSS

Trans-Air-Link $1,930 ($220) 0 0 0 0 0 FL NSS

Winair $4,939 ($1,150) 0 0 0 0 0 UT 6 mos.

[1] Notes: NSS: provided unscheduled services only.

Chap. 11: Kiwi Airlines filed for Chapter 11 bankruptcy protection 3/16/99.

6 mos.:financial data for 6 month period ending 6/30/98.

[2] Valujet merged with AirTran 3/98.

[3] Flagship, Simmons, and Wings West merged to become American Eagle, 6/1/98.

[4] Wholly owned subsidiary of a major air carrier.

Source: References (29, 32)
D-4

U.S. Small Certificated and Commuter Airlines, 1997 - 1998

12 month period ending 6/30/98

Air Carrier (x 1,000) (x 1,000) (x 1,000) (x 1,000 (x 1,000) Sharing [1] State

Passenger Revenue

Enplane- Passenger Available Seat Passenger Cargo

ments Miles Miles Ton-miles Ton-miles Code- HQ

Fourth Quartile

Comair 5,005,338 1,883,205 3,048,664 188,320,481 Y OH

Mesa 4,151,202 1,044,158 1,856,093 104,415,813 Y NM

Third Quartile

Allegheny [3] 2,029,870 377,435 749,700 37,743,527 200,897 Y PA

Piedmont [3] 2,906,282 585,507 1,026,577 58,550,692 285,102 Y NC

Sky West 3,212,231 772,072 1,484,829 77,207,248 Y UT

Second Quartile

Atlantic Coast 1,854,888 584,279 1,085,484 58,427,900 Y VA

Business Express 1,290,122 283,542 741,247 28,340,677 2,587 Y NH

CC Air 776,663 141,304 254,142 14,130,398 1 Y NC

Express Airlines I [3] 1,291,814 369,664 618,605 36,966,354 Y TX

PSA [3] 1,190,126 393,392 611,206 39,239,146 Y

Westair 1,467,951 231,378 391,277 23,137,785 CA

First Quartile

Action 1,670 103 156 10,281

Air Midwest 474,024 91,841 199,493 9,184,096 KS

Air Nevada 41,536 7,488 9,665 748,751 HI

Air St. Thomas 11,071 1,032 1,877 103,189

Air Sunshine 26,860 3,278 7,449 327,750

Air Vegas 117,528 21,425 29,581 2,142,549

Alaska Seaplane Service 2,513 152 680 14,510 5,865 AK

Aloha Island 470,637 31,407 53,727 3,140,677 Y

Alpine Air 6,129 1,056 4,744 105,640 3

Astral Aviation 291,822 71,791 161,175 7,179,148 100,167 WI

Austin Express [2] 3,322 701 3,671 70,120 42

Baker Aviation 17,840 1,352 5,256 135,229 97,590 AK

Bemidji 25 5 102 500 24,119

Bering Air 45,699 6,178 15,602 617,784 243,102 AK

Big Sky 43,118 9,163 29,637 43,118 10,209 MT

Cape Air 388,348 21,212 41,717 2,121,183 8,464

Cape Smythe Air 43,712 5,704 14,826 570,416 299,202 AK

Casino [2] 2,632 190,299 1,199,470 19,029,892

Chautauqua 704,775 157,891 317,604 15,789,078 56,232 Y

Coastal Air Transport 2,409 361 520 36,135 723

Colgan Air 97,225 16,506 51,620 1,461,525 133,493 Y

Commutair 630,827 117,374 271,088 11,737,425 Y

Corporate Flight Management 160,177 37,189 86,824 3,718,930 1,322
U.S. Small Certificated and Commuter Airlines, 1997 - 1998 (Continued)

12 month period ending 6/30/98

Air Carrier (x 1,000) (x 1,000) (x 1,000) (x 1,000 (x 1,000) Sharing [1] State

Passenger Revenue

Enplane- Passenger Available Seat Passenger Cargo

ments Miles Miles Ton-miles Ton-miles Code- HQ

D-5

Eagle Canyon 199,079 35,834 50,227 3,583,422 NV

Ellis Air Taxi 400 52 200 4,175 1,441

Era Aviation 418,640 51,950 104,071 5,195,049 385,973 Y AK

Exec Express II 227,333 99,198 249,878 9,919,828 116,142 Y TX

Flying Boat 35,413 3,180 5,213 318,004

Forty-Mile Air 2,367 176 1,031 17,650 20,927 AK

Freedom Air 77,201 2,557 12,438 255,721 35,783

Frontier Flying Service 37,548 9,471 26,572 947,058 476,619 AK

F.S. Air Service 1,203 152 772 15,168 10,253 AK

Grand Canyon Helicopters 1,156 70 113 6,960 77

Grant Aviation 20,692 3,288 10,858 328,834 112,466 AK

Great Lakes Aviation 668,149 195,734 395,072 19,573,445 Y

Gulf Air Taxi 242 23 108 1,644 1,198

Gulfstream Int’l. 583,118 111,145 205,692 11,114,522 1,023,024 Y

Hageland Aviation 54,098 5,171 15,364 517,134 285,006 AK

Haines 22,874 762 1,607 76,212 38,680 AK

Harbor 63,956 4,499 13,908 449,920 3,837 Y

Iliamna Air Taxi 450 10 261 1,041 12,941 AK

Island Express 15,164 2,888 6,417 288,756 17,266

Jim Air 860 144 629 14,425 27,635 AK

Katmai Air [2] 8,348 275 511 27,549 1,334 AK

Kenmore Air Harbor 51,974 4,155 7,730 415,515

Larry’s Flying Service 7,569 990 5,353 98,956 99,270 AK

Las Vegas 8,340 749 1,077 74,944 2,191

L.A.B. Flying Service 32,966 2,215 3,477 221,480 99,285 AK

Merlin Express 52,216 15,423 42,272 1,542,263 116,986

New England 25,031 426 958 25,031 559

Olson Air Service 4,883 423 2,736 42,229 40,192 AK

Pacific Island 89,895 5,455 10,613 545,524 545,524

Paradise Island 242,066 42,612 75,957 4,261,205

Peninsula 179,334 45,976 99,724 4,597,570 320,674 Y AK

Pine State 1,545 390 1,319 39,013 2

Pro Air 160,602 73,399 308,727 7,339,767 WA

Promech 18,667 661 2,166 66,082 17,697 AK

Redwing 2,566 331 1,598 33,101

Samoa Aviation 71,675 6,972 10,244 696,949 8,576

Scenic 286,418 49,861 67,382 4,986,054

Seaborne Aviation 63,275 2,385 3,637 238,547 AK
U.S. Small Certificated and Commuter Airlines, 1997 - 1998 (Continued)

12 month period ending 6/30/98

Air Carrier (x 1,000) (x 1,000) (x 1,000) (x 1,000 (x 1,000) Sharing [1] State

Passenger Revenue

Enplane- Passenger Available Seat Passenger Cargo

ments Miles Miles Ton-miles Ton-miles Code- HQ

D-6

Skagway Air Service 10,099 803 1,711 80,292 15,849 AK

Southcentral Air 42,158 2,873 10,258 287,285 65,777 AK

Springdale Air 1,065 154 456 15,443 2,668

Sunrise [2] 448 59 226 5,869

Tanana Air Service 4,329 369 2,612 36,912 70,118 AK

Taquan Air Service 113,304 3,375 17,500 312,398 147,036 AK

Viesques Air Link 76,815 2,434 3,934 243,366

Village Aviation 196 1 22 112 251 AK

Warbelow’s Air Ventures 32,418 6,855 17,724 685,543 584,609 AK

Ward Air 43 1 9 96 25

West Isle Air 26,436 1,029 2,602 102,925 976

Wings of Alaska 29,234 1,414 4,454 141,358 35,725 AK

Wright Air Service 10,755 1,729 5,139 172,850 81,796 AK

Yute Air Alaska 74,223 5,804 17,410 580,351 237,778 AK

[1] Carrier has code-sharing arrangements with one or more major airlines;

source: RAA website: http:/www.raa.org/newsdesk/archive/Codeshare.htm.

[2] Carrier started service within 12 month period; less than full year’s data provided.

[3] Wholly-owned subsidiary of a major air carrier.

Source: Reference (31)