United States
Environmental Protection
Agency
Office of Water (4303)
Washington, DC 20460
EPA-821-R-00-016
August 2000
Preliminary Data Summary
Airport Deicing Operations
(Revised)
39 Printed on paper containing at least 30% postconsumer recovered fiber.
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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.
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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
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TABLE OF CONTENTS (Continued)
Page
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
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TABLE OF CONTENTS (Continued)
Page
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 AircraftDeicingFacilities 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
in
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TABLE OF CONTENTS (Continued)
Page
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 IMPACT s FROM THE DISCHARGE OF DEICING/ANTI-ICING AGENT-
CONTAMINATED STORM WATER 10-1
10.1 Degradability and Environmental Fate of Dei cing/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
IV
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TABLE OF CONTENTS (Continued)
Page
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 EPAPOTW Questionnaires 10-18
10.3.1.1 Chemicals Typically Found in Discharges ... 10-18
10.3.1.2 Contribution of Wastewater Containing
Dei cing/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 Dei cing/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 Dei cing/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 Mtigation 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
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TABLE OF CONTENTS (Continued)
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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/Anti-
Icing 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
VI
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TABLE OF CONTENTS (Continued)
Page
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
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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
Vlll
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LIST OF TABLES (Continued)
Page
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
IX
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LIST OF TABLES (Continued)
Page
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
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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
XI
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Section 1.0 - Executive Summary
i.o 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
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Section 1.0 - Executive Summary
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 take-
offs or landings) annually, excluding general aviation1 operations. These airports are very diverse
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
1 General Aviation (GA) operations are the portion of civil (i.e., non-military) aviation which encompasses all facets of
aviation except air carriers (e.g., passenger and cargo airlines).
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Section 1.0 - Executive Summary
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:
Increased use of propylene glycol-based aircraft deicing fluids over use of
ethylene glycol-based fluids;
Increased use of anti-icing fluids as a means of reducing the volumes of
deicing fluid needed;
Increased efforts by the industry to procure fluids with additives that are
less toxic to aquatic life;
Increased use of alternative airfield pavement deicing chemicals, such as
potassium acetate, as a replacement for urea or ethylene glycol-based
pavement deicers;
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;
Increased use of systems for glycol recycling/recovery from spent aircraft
deicing fluid; and
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Section 1.0 - Executive Summary
• 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 BOD5.
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
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Section 1.0 - Executive Summary
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
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Section 1.0 - Executive Summary
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.
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Section 2.0 - Introduction
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:
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Section 2.0 - Introduction
"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 decrei
document describes data-collection activities (Section 3.0), a technical profile of the industi
(Section 4.0), climatic influences and deicing/anti-icing agent- contaminated storm water
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Section 2.0 - Introduction
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).
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Section 3.0 - Data-Collection Activities
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 data-
editing 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 mini-
questionnaires, 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 TECI-
Aircraft 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
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Section 3.0 - Data-Collection Activities
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
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Section 3.0 - Data-Collection Activities
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.
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Section 3.0 - Data-Collection Activities
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 Dei cing/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
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Section 3.0 - Data-Collection Activities
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:
Section 1: General Information;
Section 2: Information on Specific Equipment and Services;
Section 3: Rates and Charges;
Section 4: Future Operations;
Section 5: Wastewater Treatment and Recycling/Recovery;
Section 6: Process Influent and Effluent;
Section 7: Residuals and Solid Waste; and
Section 8: Additional Information.
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Section 3.0 - Data-Collection Activities
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:
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Section 3.0 - Data-Collection Activities
• Section 1: General/Background Information; and
• 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.
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Section 3.0 - Data-Collection Activities
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:
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;
A general description of deicing/anti-icing operations, including equipment
used, location(s) of deicing operations, chemicals used, and pollution
prevention techniques employed;
Volumes, specific procedures, and type of fluid used for aircraft and
pavement deicing/anti-icing;
Wastewater characterization information, including the typical volume of
ADF-contaminated storm water generated, collection methods used, and
pollutant concentrations;
On-site wastewater treatment data, including the treatment technologies
used, treatment costs, monitoring, discharge, and permit information; and
Airport financial information.
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Section 3.0 - Data-Collection Activities
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:
• Storm water outfall which drains aircraft deicing/anti-icing areas (sample
collected during the deicing season, but not concurrent with a deicing
event);
• Wastewater discharge to a POTW from an airport retention basin used to
collect ADF-contaminated wastewater;
• Influent to and effluent from an anaerobic biological treatment system used
to treat ADF-contaminated wastewater at an airport;
• 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;
• Influent to and effluent from an aerobic biological treatment system used to
treat ADF-contaminated wastewater;
• Undiluted propylene glycol-based aircraft deicing fluid;
• Undiluted ethylene glycol-based aircraft deicing fluid;
• Trip blank(s);
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Section 3.0 - Data-Collection Activities
• Equipment blank(s); and
• Duplicate wastewater samples.
In general, the following classes of pollutants were analyzed:
• Whole effluent acute toxicity (WET)
- Pimephales Promelas (Fathead Minnow),
- Ceriodaphnia Dubia;
• Volatile organics (at only two sampling episodes);
• Semivolatile organics (including tolyltriazoles);
• Metals;
• Glycols;
• Biochemical oxygen demand, 5-day (BOD5);
• Total organic carbon (TOC);
• Hexane extractable material (HEM) and non-polar material (SGT-HEM);
and
• 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, FIEM, 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.
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Section 3.0 - Data-Collection Activities
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 BAD
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.
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Section 3.0 - Data-Collection Activities
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:
• Federal Aviation Administration;
• 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
• 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
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Section 3.0 - Data-Collection Activities
- Union Carbide.
In addition to meetings, EPA also attended the following industry conferences:
• The Seventh Annual Aircraft and Airfield Deicing Conference and
Exposition held in Washington, DC in August 1998;
• Society of Automotive Engineers (SAE) G-12 Deicing Facilities
Subcommittee Meeting in Orlando, FL in October 1998;
• National Aviation Environmental Management Conference in Columbus,
OH in March 1999;
• Airport Deicing Summit (hosted by the Albany International Airport
Authority) in March 1999;
• The Clean Airport Summit held in Chicago, IL in April 1999;
• SAE G-12 Committee Meeting in Toronto, Canada in May 1999;
• The Eighth Annual Aircraft and Airfield Deicing Conference and
Exposition held in Washington, DC in August 1999; and
• 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-to-
date 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
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Section 3.0 - Data-Collection Activities
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
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Section 3.0 - Data-Collection Activities
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
Eastern Research Group, Inc. Development of Survey Weights for the U.S.
Environmental Protection Agency Aircraft and Pavement Screener Questionnaire
(DCN T10343).
Eastern Research Group, Inc. Methodology for Selection of Mini-Questionnaire
Recipients. (DCN T10545).
Eastern Research Group, Inc. Quality Assurance Project Plan for Field Sampling
and Analysis at Airports. February 10, 1999 (DCN T10233).
Viar and Company. BAD Sampling Guide. June 1991 (DCN T10218).
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Section 3.0 - Data-Collection Activities
Table 3-1
Summary of Data Submitted by Airports
Airport
Airborne Air Park
Albany International
Anchorage International
Baltimore-Washington International
Billings Logan International
Bradley International
Buffalo International
Chicago O'Hare International
Cleveland Hopkins International
Dallas-Ft. Worth International
Denver International
Des Moines International
Duluth International
General Mitchell International
Greater Rockford
Kansas City International
Key Field (Meridian)
Logan International
Minneapolis-St. Paul International
Newark International
Portland International
Richmond International
Ronald Reagan Washington National
Seattle-Tacoma International
Salt Lake City International
Tri- State (Huntington)
Washington Dulles International
Permit
Information (a)
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
N/A
•
•
•
•
•
Analytical
Monitoring Data
•
•
•
•
•
•
•
•
•
•
•
ADF Usage Volumes
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
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.
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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 areas1 in the U.S., which include airports
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
'Note that civil landing areas do not include stand-alone military landing areas (i.e., military landing areas that are not
located at a public airport).
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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
Commercial
Primary
Non-
primary
Large hub
Medium hub
Small hub
Nonhub
Other
Relievers
General aviation
Number of Airports
29
42
70
272
125
334
2,472
Percentage of U.S. Enplanements
67%
22%
7%
3%
<1%
0%
0%
Source: Reference (1).
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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
Air carrier
Air taxi
General aviation
Military
Definition
A certified aircraft with a seating capacity of more than 60 seats or a
maximum pay load 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.
An aircraft designed to have a maximum seating capacity of 60 seats or
less or a maximum pay load 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.
Takeoffs and landings of all civil aircraft, except those classified as air
carriers or air taxis.
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).
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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
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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 build-
up on runways, taxiways, roadways, gate areas, and aircraft. Two basic types of deicing/anti-
icing 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 anti-
icing 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.
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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 l/32nd of an inch of ice accumulation along the leading edge of a large jet or
l/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
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formation at lower altitudes and after landing. Dry-weather deicing may occur at temperatures up
to 55 ° 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 anti-
icing 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
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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 20° F
below the ambient air or aircraft surface temperature, whichever is lower (FAA Advisory Circular
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No. 20-117). All ADFs must lower the freezing point of water to -18° 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 -40° F and -
50° 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 -58° F) occurs when the
fluid consists of approximately 60% ethylene glycol and 40% water. The minimum freeze point
for propylene glycol-based ADFs (-75 ° 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 anti-
icing 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
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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 150° F to 180° 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 26° F, the FAA allows the use of
hot water (heated to 140° F) to melt and remove snow and ice followed by application of anti-
icing 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.
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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.
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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.
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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 FAA-
mandated 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 55° 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.
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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 forced-
air 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
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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.
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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.
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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
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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
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Section 4.0 - Technical Profile
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
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Section 4.0 - Technical Profile
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/anti-
icing, 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).
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Section 4.0 - Technical Profile
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).
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Section 4.0 - Technical Profile
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
Type I ethylene gly col-based
Type II/IV ethylene gly col-based
Type I propylene gly col-based
Type II/IV propylene gly col-based
Range of Volumes Used Per Airport (Gallons/Year)
3,500 - 700,000(a)
600- 180,000
257 - 833,000(a)
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
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Section 4.0 - Technical Profile
propylene gly col-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 fNPIAS^ 1998 - 2002. Washington, D.C., 1999 (DCN Tl 1096).
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).
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Section 4.0 - Technical Profile
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 Tl 1073).
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Section 4.0 - Technical Profile
Figure 4-1
Geographic Distribution of Airports with Annual Operations Greater than 10,000 and
Mean Annual Snowfall Greater than 1 Inch
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Section 5.0 - Climactic Influences and Deicing/Anti-Icing
Agent-Contaminated Wastewater Generation and Discharge
5.0 CLIMATIC INFLUENCES AND DEICING/ANTI-ICING AGENT-
CONTAMINATED 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 agent-
contaminated 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/anti-
icing 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
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Section 5.0 - Climactic Influences and Deicing/Anti-Icing
Agent-Contaminated Wastewater Generation and Discharge
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
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Section 5.0 - Climactic Influences and Deicing/Anti-Icing
Agent-Contaminated Wastewater Generation and Discharge
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.
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Section 5.0 - Climactic Influences and Deicing/Anti-Icing
Agent-Contaminated Wastewater Generation and Discharge
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 32° 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 32° 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 65° F. For example, if the mean temperature for a given day is 40° F, then
there are 25 heating degree days associated with that calendar day. If the daily mean temperature
is 65° 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
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Section 5.0 - Climactic Influences and Deicing/Anti-Icing
Agent-Contaminated Wastewater Generation and Discharge
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.
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Section 5.0 - Climactic Influences and Deicing/Anti-Icing
Agent-Contaminated Wastewater Generation and Discharge
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 agent-
contaminated 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.
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Section 5.0 - Climactic Influences and Deicing/Anti-Icing
Agent-Contaminated Wastewater Generation and Discharge
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 co-
permittees 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. (DCNT10694).
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 Tl 1073).
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Section 6.0 - Pollution Prevention
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 technology-
specific 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 gly col-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 gly col 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
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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
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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-King 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-
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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 gly col-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 gly col-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).
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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
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(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
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from aircraft surfaces using a high-pressure air stream combined with a fine spray of gly col-based
aircraft deicing fluid. The system is known as the AirFirst Deicing System™ and can be used in
an air-only mode for removing light snow and ice. The system consists of a self-contained, truck-
mounted 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 System™. The Premier
system, known as the Hybrid Deicing System™ (FIDS), was developed in collaboration with
Allied Signal and consists of a centrifugal compressor, an ADF storage tank with heater, a high-
pressure 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. FIDS 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 AirPlus™, 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
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in the enclosed cab attached to the articulated boom. AirPlus™ 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 AirPlus™ 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 AirPlus™ 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, forced-
air 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
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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 MAI A 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).
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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 computer-
controlled, 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 Wash™, has been developed by
Catalyst and Chemical Service, Inc. The Whisper Wash™ 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 low-
pressure deicing fluid. The nozzles used to deliver the deicing fluid are specially designed low-
shear nozzles, which can be used to apply Type IV fluids as well as Type I fluids. The Whisper
Wash™ system can also be operated in an air-only mode to remove light snow. According to the
manufacturers, Whisper Wash™ 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
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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 Wash™ 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 InfraTek™, while Infra-
Red Technologies markets a mobile system known as Ice Cat™. Both systems have the potential
to greatly reduce the amount of gly col-based fluids used for aircraft deicing. Neither system is
widely used by airlines or airports, although the InfraTek™ system is currently in commercial use
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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.
InfraTek™
InfraTek™ 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 InfraTek™ 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 94° F. Based on these results, the FAA approved deicing/anti-
icing procedures that use the InfraTek™ system for commercial aircraft in 1997 (18).
The InfraTek™ 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.
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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 InfraTek™ 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 InfraTek™ 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). InfraTek™ 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 InfraTek™ 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 InfraTek™ 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 InfraTek™ 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 InfraTek™ 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,
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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 InfraTek™ system reportedly
costs less than traditional deicing with deicing agents. InfraTek™ reportedly deices a Boeing 727
for under $350, compared with the cost of approximately $5,000 for deicing the same aircraft
with gly col-based fluids (2).
Radiant Energy markets several different hangar sizes for the InfraTek™ 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 InfraTek™ system depends on
the size of the hangar and ranges from $1 million to $4 million (5).
The principle disadvantages of the InfraTek™ system are its physical size and
aircraft processing capacity. Land-locked airports located in urban areas may have difficulty
finding sites for the InfraTek™ 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 InfraTek™ 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).
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Ice Cat™
The Ice Cat™ 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 Cat™ 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 Cat™ 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 140° F (23).
Infra-Red Technologies sponsored a demonstration of the Ice Cat™ 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 Cat™ was used to deice a
Boeing 727 and at the Pittsburgh National Guard Base where it was used to deice a military KC-
135 supertanker. Ice Cat™ 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 Cat™
and recently added a spray system designed to apply a light coating of Type IV (anti-icing) fluid.
Ice Cat™ is reportedly a cost-effective alternative to deicing with traditional
glycol-based aircraft deicing agents. According to the manufacturer, Ice-Cat™ 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 Cat™
system is currently known. Although Ice-Cat™ is equipped with temperature sensors, many U.S.
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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-Cat™ difficult to maneuver in the confined space
of the gate area. Airlines are concerned about the potential for collisions between Ice-Cat™ 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/cm2. For safety, the laser beam will be
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 27° 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.
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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
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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.
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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.
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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.
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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 System™ (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 System™. 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 IceHawk™ Wide Area Ice Detector, which uses an infrared light
beam to detect ice, snow, and frost on aircraft surfaces. The IceHawk™ is designed to detect
frozen contamination up to 60 feet from the aircraft and has been approved by the FAA to replace
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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 IceHawk™ 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%
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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
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experienced delcing/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.
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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
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pounds of super-cooled fuel stored in its tanks. Polaris introduced 1,000 pounds of heated fuel
(heated to approximately 85° 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
10° F. Additional heated fuel was added at 2:20 a.m. and 3:00 a.m., raising the average wing
surface temperature to 79° F. Although the ambient temperature was about 18° 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 glycol-
vacuum 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.
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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, Minneapolis-
St. 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
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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
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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.
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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.
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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
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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.
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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/anti-
icing 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
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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.
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Ro-Mat™
Ro-Mat™ is manufactured by the Danish company A/S Roulunds Fabriker and
consists of a thick rubber mat that can tolerate temperatures ranging from -50° C to 50° 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-Mat™ costs approximately $22 per square foot (5, 38).
The Ro-Mat™ 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-Mat™, 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).
Latimat™
Environmental Cleaning Systems, Inc. has developed a containment pad system
called Latimat™, 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 Latimat™ available can accommodate a Boeing 747 aircraft (39).
Pure Mat™
Recovery Systems, Inc. manufactures a containment system similar to Latimat™
called Pure Mat™. The Pure Mat™ 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).
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Remote Aircraft Wash Platform and Portable Evacuation System™
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 gly col-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
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$1,800 and have a life expectancy of approximately 7 years. AR Plus also manufacture custom-
made 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
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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 (GRV™). The GRV™ consists
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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). GRVs™ cost approximately $262,000.
Three GRVs™ 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 GRVs™ are owned by the glycol recycler Inland Technologies, Ltd, but are
leased, operated, and maintained by Northwest Airlines. Other airports using GRVs™ 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
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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
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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 VOuip
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 Ranger™ and larger trailer-mounted units. Both types are currently in use at Bradley
International Airport in Hartford, Connecticut. The truck-mounted Ramp Ranger™ uses a high-
pressure 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 Ranger™ 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 Rangers™
can clean residual ADF from airfield pavements. Tests conducted by VQuip showed that the first
pass of the Ramp Ranger™ 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 trailer-
mounted Ramp Rangers™ were equipped with an 1,800-gallon wastewater storage tank. The
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Ramp Ranger™ 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 high-
capacity 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 Ranger™ 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
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Interceptor™, is currently in use at Bradley International Airport in Connecticut and Washington
Dulles International Airport in Virginia. The Interceptor™ is particularly useful for airports
engaging in glycol recovery/recycling programs.
The Interceptor™ 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 Interceptor™ 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.
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The Interceptor™ can be used for ethylene glycol- or propylene glycol-
contaminated 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.
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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
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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 ADF-
contaminated 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. ADF-
contaminated 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
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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 on-
site 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
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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 ADSL
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
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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 ethyl ene 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.
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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).
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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 (Montreal-
Mirabel 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,
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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.
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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
Propylene Glycol (mg/L)
Ethylene Glycol (mg/L)
Tolyltriazole (mg/L)
Phenol (ug/L)
Total Organic Carbon (mg/L)
Ammonia as Nitrogen (mg/L)
Hexane Extractable Material (mg/L)
Influent
to First RO Unit
160,000
3,010
90
277
35,300
22.7
173
Effluent from
First RO Unit
8,720
27.0
5.9
45.9
1,320
4.7
ND(6)
Effluent to
POTW
62.7
ND(10)
0.13
ND(10)
11.3
0.29
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
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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).
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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.
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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 cost-
effective method of disposal even when the revenues from the sale of recovered glycol do not
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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.
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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.
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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 acetate-
based deicers/anti-icers. The U.S. Air Force, which banned the use of ethylene glycol-based
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aircraft and pavement delcing/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 SNOWFREE™ 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
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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 SNOWFREE™ 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 truck-
mounted pavement heating system called the Heat Master™. 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 Master™ 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
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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:
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;
Using mechanical methods to remove dry snow from airfield pavements,
rather than applying deicing/anti-icing chemicals;
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;
Applying pavement deicing/anti-icing chemicals at rates recommended by
the manufacturer;
Frequently recalibrating chemical and abrasive spreading equipment to
ensure an optimal application rate;
Monitoring weather conditions and obtaining accurate weather forecasts
from the National Weather Service or a private contractor;
Preventing snow from drifting across runways and taxiways by installing
snow fences or constructing snow trenches;
Avoiding heavy applications of sand, which can insulate ice and snow from
solar radiation and deicing chemicals;
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• Storing solid pavement deicing/anti-icing chemicals in enclosed buildings to
prevent product degradation and leaching by storm water; and
• 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,
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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).
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Section 6.0 - Pollution Prevention
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 (RWIS™) for use by highway maintenance agencies and airport authorities. RWIS™
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 ICELERT™, 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. ICELERT™ is a surface condition
monitoring system that uses information from pavement surface sensors, ground temperature
probes, and atmospheric sensors to predict icing conditions. ICELERT™'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
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Section 6.0 - Pollution Prevention
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 infrared-
based 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
Bremer, Karl. The Double Deicing Dilema.
http://www.airportnet.org/depts/publicat/airmags/am91093/deicing.htm (accessed
November 1997) (DCN T4678).
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).
Noble, Denise L. "Controlling Glycol Runoff," Environmental Technology. 1997,
7(5), pp 46-48 (DCN T4677).
Dennis, Ron. Aircraft Deicing/Anti-icing: Howgozit?
http://www.ftsbn.com/~gsetoday/697_4.htm (accessed November 1997) (DCN
T4675).
U.S. Air Force Air Combat Command. Literature and Technology Review Report
for Aircraft and Airfield Deicing. September 1997 (DCN T10450).
U.S.A. Today. New Help for Deicing Decisions Being Tested.
http://www.usatoday.com/weather/wpilga.htm (accessed November 1997) (DCN
T4682).
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Section 6.0 - Pollution Prevention
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. Berts, 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-l.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 Tl 1044).
17. Canada News Wire. http://www.newswire.ca/releases/Januaryl997/16/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).
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Section 6.0 - Pollution Prevention
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 T103 79).
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 (DCNT10427).
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).
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Section 6.0 - Pollution Prevention
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, PJ. 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, DCNT10594).
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 Tl 1082).
47. AR Plus Equipment Rentals (USA), Inc. promotional literature (DCN T10396).
48. Trecan Combustion Limited, promotional literature (DCN Tl 1020).
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 Tl 1047).
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Section 6.0 - Pollution Prevention
52. Inland Technologies, Ltd. promotional literature (DCN T10363, DCN T10370).
53. Superior Graphite Company, promotional literature (DCN Tl 1011).
54. Small Business Innovation Research Program.
http://sbir.gsfc.nasa.gov/95abstracts/06.01/950901 .html (accessed September
1999) (DCN Til012).
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 Tl 1016).
57. Findlay, Irvine Ltd., promotional literature (DCN Tl 1017).
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Section 7.0 - Wastewater Containment and Treatment
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/anti-
icing 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
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Section 7.0 - Wastewater Containment and Treatment
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-Aiianda 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
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Section 7.0 - Wastewater Containment and Treatment
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 gly col-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.
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Section 7.0 - Wastewater Containment and Treatment
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 (DFW1
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
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Section 7.0 - Wastewater Containment and Treatment
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).
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Section 7.0 - Wastewater Containment and Treatment
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 (SLO
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.
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Section 7.0 - Wastewater Containment and Treatment
Buffalo-Niagara International Airport. Buffalo. NY (BUFt
In areas where aircraft deicing/anti-icing operations are performed, Buffalo-
Niagara 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 (ADF-
contaminated 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 BOD5 loading.
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.
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Section 7.0 - Wastewater Containment and Treatment
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.
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Section 7.0 - Wastewater Containment and Treatment
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.
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Section 7.0 - Wastewater Containment and Treatment
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
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Section 7.0 - Wastewater Containment and Treatment
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 off-
site 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 pond-
based 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 (RFD1
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
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Section 7.0 - Wastewater Containment and Treatment
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-million-
gallon 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
70°F 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).
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Section 7.0 - Wastewater Containment and Treatment
Pollutant
Propylene Glycol (mg/L)
Ethylene Glycol (mg/L)
Tolyltriazole (mg/L)
Phenol (ug/L)
Total Organic Carbon (mg/L)
Ammonia as Nitrogen (mg/L)
Hexane Extractable Material (mg/L)
Influent Concentration
ND(5)
ND(10)
0.12
ND(10)
12
46
100
Effluent Concentration
ND(5)
ND(10)
0.013
ND(10)
9.0
0.27
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
Biochemical Oxygen Demand, 5-Day
(mg/L)
Ammonia as Nitrogen (mg/L)
Total Suspended Solids (mg/L)
Detention Pond Concentration
Average
37
24
38
Range
ND(10)-98
ND (0.5) - 82
ND (5) - 325
Discharge Concentration
Average
5.3
0.5
7.1
Range
3-10
0.5-0.55
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.
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Section 7.0 - Wastewater Containment and Treatment
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.
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Section 7.0 - Wastewater Containment and Treatment
Pollutant
Propylene Glycol (mg/L)
Ethylene Glycol (mg/L)
Tolyltriazole (mg/L)
Phenol (ug/L)
Total Organic Carbon (mg/L)
Ammonia as Nitrogen (mg/L) (a)
Hexane Extractable Material (mg/L)
Influent Concentration
2,700
ND(10)
>2.00
109
2,420
88.1
ND(6)
Effluent Concentration
ND(5)
ND(10)
0.107
ND(10)
ND(10)
87.2
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
Propylene Glycol (mg/L)
Biochemical Oxygen Demand, 5-Day
(mg/L)
Chemical Oxygen Demand (mg/L)
Influent Concentration
Average
4,400
NA
8,600
Range
3,400 - 5,500
NA
420 - 9,300
Effluent Concentration
Average
0.28
57
110
Range
ND (0.05) - 0.85
39-75
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 full-
scale system is currently under construction for use beginning in the 2000-2001 deicing season to
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Section 7.0 - Wastewater Containment and Treatment
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
Treatment
System Type
Conventional
Reciprocating
Removal Rate
(Ib COD per
mgal per ft3 of
substrate)
0.6
7.5
Average
Influent COD
(mg/L)
959
1960
Average
Effluent COD
(mg/L)
783
383
Range of
Influent COD
Treated
(mg/L)
100 to 500
260 to 12,000
Range of
Effluent COD
(mg/L)
24 to 3 80
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
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Section 7.0 - Wastewater Containment and Treatment
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 50° 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).
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Section 7.0 - Wastewater Containment and Treatment
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).
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Section 7.0 - Wastewater Containment and Treatment
Table 7-1
Summary of Wastewater Containment and Treatment at Airports
Airport
Portland International Airport (PDX)
Billings Logan International Airport (BIL)
Chicago O'Hare International Airport (ORD)
Minneapolis-St. Paul International Airport (MSP)
Dallas/Ft. Worth International Airport (DFW)
Denver International Airport (DIA)
Salt Lake City International Airport (SLC)
Buffalo-Niagara International Airport (BUF)
Kansas City International Airport (MCI)
Baltimore/Washington International Airport (BWI)
Des Moines International Airport (DSM)
Hopkins International Airport (CLE)
Washington Dulles International Airport (IAD)
Munich Airport (MUG)
Stockholm-Arlanda Airport (ARN)
Greater Rockford Airport (RFD)
Duluth International Airport (DLH)
Albany International Airport (ALB)
Airborne Air Park (ILN)
ADF-Contaminated
Wastewater Collection/Treatment
High strength to POTW
Low strength to pond and direct discharge
Retained in a series of ponds; direct discharge in spring
Retained in ponds; discharge to POTW
High strength to glycol recycling
Low strength to ponds; discharge to POTW
Retained in detention basins; discharge to POTW
Deicing pad runoff to glycol recycling. Gate runoff to
detention ponds; discharge to POTW
High strength to glycol recycling
Low strength to detention pond; discharge to POTW
Retained in underground storage basins; discharge to
POTW
Retained in storage basins; discharge to POTW
Retained in storage tanks; discharge to POTW
Runway and taxiway runoff to infiltration system
Retained in storage tank; discharge to POTW
High strength to glycol recycling
Low strength to storage tanks; discharge to POTW
High strength to glycol recycling
Low strength to storage tank; discharge to POTW
Runway runoff to basins; discharge to POTW
Taxiway runoff to on-site biodegradation treatment system
Runway runoff drainage system to direct discharge
Retained in aerated detention pond; direct discharge in
summer
Retained in aerated retention pond; direct discharge
Retention ponds and storage tank to on-site anaerobic
fluidized bed reactor; discharge to POTW or land
application
Drainage to on-site reciprocating aerobic/anaerobic
treatment system; direct discharge
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Section 8.0 - Wastewater Characterization
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
8-1
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Section 8.0 - Wastewater Characterization
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/anti-
icing 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
8-2
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Section 8.0 - Wastewater Characterization
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.
Propylene Glycol
Ethylene Glycol
Average Concentration (mg/L)
<61.1
<5.52
Range (mg/L)
ND (5) - 986
ND (5) - 34
Number of Data Points
124
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.
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Section 8.0 - Wastewater Characterization
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
3/15/91
1/23/92
3/19/92
Avg.
North Outfall (mg/L)
PG
120
ND(1)
<141
<87.3
EG
110
1,100
<641
<617
BOD5
8,320
592
N/A
4,456
Ammonia
2.3
5.3
N/A
3.8
West Outfall (mg/L)
PG
240
130
<218
<196
EG
95
280
481
285
BOD5
5,500
531
N/A
3,016
Ammonia
2.9
3.8
N/A
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.
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Section 8.0 - Wastewater Characterization
1997-1998 Season
Average glycol concentration
(mg/L)
Range of glycol concentrations
(mg/L)
Range of COD concentrations
Range of ammonia concentrations
(mg/L)
Number of Data Points
Kitten Branch Watershed
<10
ND (6) - 630
ND(10)-400
ND(1)
159
Muddy Bridge Branch Watershed
<8.7
ND (6) - 30
ND(10)-690
ND(1)-1.3
159
< - Maximum concentration
ND - Not detected (followed by detection limit).
General Mitchell International Airport
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.
Average EG Concentration (mg/L)
Average PG Concentration (mg/L)
Average BOD5 Concentration (mg/L)
Number of Data Points
Outfall #1
170
5,080
3,510
4
Outfall #7
123
1,460
917
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.
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Section 8.0 - Wastewater Characterization
Data from this event were used to establish acute and chronic toxic criteria for the fathead
minnow and Ceriodaphnia dubia as follows:
Species
Fathead minnow
Ceriodaphnia dubia
Duration
96-hour LC50
7-day IC25
48-hour LC50
7-day IC25
Aircraft Deicing/ Anti-icing Fluid Concentration (mg/L)
1,650
90
3,150
1,015
LC50 - Lethal concentration at which 50% of the test population dies.
IC25 - Concentration at which 25% of the test organisms had inhibited growth, reproduction, or survival of the young.
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
St. John's
Quebec City (A)
Quebec City (B)
Thunder Bay
Victoria (A)
Victoria (B)
Halifax
Range of Total Glycol
Concentration
(mg/L)
ND(1)-120
ND (1) - 30,200
ND(l)-2
ND(l)-437
ND(l)-7
ND(l)-77
ND (5) -130,000
% of Samples
that Exceeded
100 mg/L
1
17.2
0
5.9
0
0
28
Range of Ammonia
Concentration
(mg/L)
ND(1)-1.85
ND(0.03)- 197
ND (0.02) - 4.63
ND (0.03) - 106
ND (0.03) - 27
ND(0.03)- 11
ND (0.05) - 55
Range of BOD5
Concentration
(mg/L)
ND(l)-89
ND(1)- 3,900
3-47
ND(1)-703
ND(l)-29
ND(l)-28
1 -31
ND - Not detected (followed by detection limit).
8-6
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Section 8.0 - Wastewater Characterization
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:
• Facility NPDES permit number;
• Facility name;
• Pipe number and description (i.e., code and description of each NPDES-
permitted discharge point);
• Name and description of analyzed parameters;
• Average quantity and/or concentration limit (and maximum and minimum
limits, if applicable);
• Units of measurement for limits;
• Average quantity and/or concentration of parameter during monitoring
period (and maximum and minimum measurements, if applicable); and
• Units of measurement for monitoring parameters.
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Section 8.0 - Wastewater Characterization
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:
Chicago O'Hare International (ORD);
Louisville International - Standiford Field (SDF);
Baltimore/Washington International (BWI);
Minneapolis-St. Paul International (MSP);
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Section 8.0 - Wastewater Characterization
Newark International (EWR);
Westchester County (HPN);
Tompkins County (ITH);
Syracuse Hancock International (SYR);
Nashville International (BNA); and
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:
• Ethylene glycol-based aircraft deicing fluid (i.e., a Type I fluid);
• Propylene glycol-based aircraft deicing fluid (i.e., a Type I fluid);
8-9
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Section 8.0 - Wastewater Characterization
Influent to and effluent from an anaerobic biological treatment system used
to treat ADF-contaminated wastewater at Albany International Airport;
Wastewater discharge to a POTW from a retention basin used to collect
ADF-contaminated wastewater at Kansas City International Airport;
Influent to and effluent from a reverse osmosis system at Bradley
International Airport used to recover glycol from low-strength ADF-
contaminated wastewater for further processing;
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
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.
8-10
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Section 8.0 - Wastewater Characterization
There are currently three principle manufacturers/femulators 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 ethyl ene 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 ethyl ene glycol-based products, and, at a few U.S. airports, the volume of
ethyl ene glycol-based fluid applied to aircraft exceeds that of propylene gly col-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
fluid (trade name Octaflo™ Concentrate, Octagon Process).
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 4° 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 gly cols, 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.
8-11
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Section 8.0 - Wastewater Characterization
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, BOD5, hexane extractable material (HEM),
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
8-12
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Section 8.0 - Wastewater Characterization
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-million-
gallon 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.
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Section 8.0 - Wastewater Characterization
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 (RFD1
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
gly col-based fluids, most of the fluid used at the airport is ethylene gly col-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
8-14
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Section 8.0 - Wastewater Characterization
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 40° 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 70° 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-lH-benzotriazole, arsenic, barium, calcium, copper, iron, lead, tin,
zinc, and ammonia. Pollutant concentrations that differed by more than an order of magnitude
8-15
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Section 8.0 - Wastewater Characterization
include those for bis(ethylhexyl) phthalate, 5-methyl-lH-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, n-
tetradecane, 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
8-16
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Section 8.0 - Wastewater Characterization
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 //g/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.
8-17
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Section 8.0 - Wastewater Characterization
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, BOD5, COD, total suspended solids
(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.
8-18
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Section 8.0 - Wastewater Characterization
Table 8-1
Summary of Storm Water Monitoring Data from
Bradley International Airport
Group
Southeast
drainage
Terminal
drainage
(South)
Location
Outfall 1A
Outfall IB
Outfall 14
Outfall 2
Outfall
3-1
Outfall
3-2
Date
2/14/91
2/27/91
3/13/91
3/4/97
3/14/98
2/2/99
3/15/99
2/14/91
2/27/91
3/13/91
3/14/98
3/14/98
2/14/91
2/27/91
3/13/91
1/28/94
3/9/94
3/4/97
3/14/98
2/2/99
3/15/99
2/14/91
2/27/91
3/13/91
1/28/94
3/9/94
3/4/97
3/14/98
2/2/99
3/15/99
3/14/98
2/2/99
3/15/99
Average BOD
Concentration
(mg/L)
28
560
11
30
NA
76
>190
31
520
3
NA
NA
8,300
6,700
32
NA
NA
69
NA
>87
50
22,000
3,200
2
NA
NA
>304
NA
>94
>190
NA
>94
>190
Average
Ammonia
Concentration
(mg/L)
2.6
6.1
0.33
0.36
NA
2.7
0.87
2.5
6.1
0.11
NA
NA
2.3
1.9
0.24
<1.8
3.1
0.61
NA
21
2.2
4.6
3.7
0.32
<0.7
3.2
1.13
NA
12
1.6
NA
29
3.8
Average
Ethylene
Glycol
Concentration
(mg/L)
11.2
43.8
0.12
ND(10)
ND(50)
ND(10)
ND(10)
10.4
20.8
ND(O.l)
ND(50)
ND(50)
11,700
6,600
10.5
<150
<103
40
ND(50)
ND(10)
ND(10)
22,500
24,000
0.29
ND(IOO)
<99
ND(10)
ND(IOO)
ND(10)
<1,700
ND( 1,000)
ND(10)
ND(10)
Average
Propylene Glycol
Concentration
(mg/L)
NA
NA
NA
ND(10)
ND(50)
ND(10)
ND(10)
NA
NA
NA
ND(50)
ND(50)
ND (500)
ND(50)
ND(10)
17,000
370
9.1
ND(50)
<280
<29
13,000
12,000
ND(10)
17,000
11,000
700
250
1,400
<340
3,600
1,200
180
8-19
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Section 8.0 - Wastewater Characterization
Table 8-1 (Continued)
Group
West
drainage
Northeast
drainage
Location
Outfall 5
Outfall 7
Outfall 8
Outfall 9
Outfall 10
Outfall
13-1
Outfall
13-2
Date
3/14/91
2/27/91
3/13/91
3/4/97
2/2/99
3/15/99
2/2/99
3/15/99
3/4/97
3/14/98
2/2/99
3/15/99
2/14/91
2/27/91
3/13/91
3/14/98
2/2/99
3/15/99
2/14/91
2/27/91
3/13/91
3/4/97
3/14/98
2/2/99
3/15/99
2/14/91
2/27/91
3/13/91
3/14/98
Average BOD
Concentration
(mg/L)
6
ND(2)
ND(2)
5.6
ND(2)
ND(15)
10
ND(15)
1.2
NA
ND(2)
ND(15)
ND(2)
ND(2)
2
NA
ND(2)
ND(15)
8
ND(2)
ND(2)
7.8
NA
7.6
>190
2
ND(2)
2
NA
Average
Ammonia
Concentration
(mg/L)
1.2
0.18
0.22
0.76
0.22
0.14
7.7
0.71
0.16
NA
1.5
0.33
1.2
0.92
0.75
NA
0.65
0.53
0.54
0.23
0.2
19.6
NA
0.46
1.1
0.47
0.13
0.51
NA
Average
Ethylene
Glycol
Concentration
(mg/L)
1.9
ND(O.l)
ND(O.l)
ND(10)
ND(10)
ND(10)
ND(10)
ND(10)
ND(10)
ND(50)
ND(10)
ND(10)
ND(O.l)
ND(O.l)
ND(O.l)
ND(50)
ND(10)
ND(10)
1.7
ND(O.l)
ND(O.l)
ND(10)
ND(50)
ND(10)
ND(10)
ND(O.l)
ND(O.l)
0.17
ND(50)
Average
Propylene Glycol
Concentration
(mg/L)
NA
NA
NA
ND(10)
ND(10)
ND(10)
ND(10)
ND(10)
ND(10)
ND(50)
ND(10)
ND(10)
NA
NA
NA
ND(50)
ND(10)
ND(10)
NA
NA
NA
ND(10)
ND(50)
ND(10)
2,100
NA
NA
NA
ND(50)
> - Minimum concentration.
< - Maximum concentration.
NA - Not available.
ND - Not detected (followed by detection limit).
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Section 8.0 - Wastewater Characterization
Table 8-2
Summary of PCS Data for Airports with EPA-Estimated Potentially
Significant Deicing/Anti-Icing Operations
Airport
Chicago
O'Hare
International
(ORD)
Louisville
International -
Standiford
Field
(SDF)
Discharge Point(s)
0110,0210,0310,
0410,0610,0810,
081 A -Storm water
(NW drainage)
0910, 1010, 1110,
1120, 1130, 1140-
Storm water (N
drainage)
1210 - Storm water
(NE drainage)
1410 - Storm water
(SE drainage)
3720,3730,4710-
Storm water (SW
drainage)
091A,091B-
drainage from
deicing activities
011,021,031,041,
06 1 - Storm water/
deicing fluid runoff
Parameter
BOD5 (mg/L)
pH (S.U.)
NH3 - N (mg/L)
IDS (mg/L)
BOD5 (mg/L)
pH(S.U.)
NH3 - N (mg/L)
IDS (mg/L)
BOD5 (mg/L)
pH(S.U.)
NH3 - N (mg/L)
IDS (mg/L)
BOD5 (mg/L)
pH(S.U.)
NH3 - N (mg/L)
IDS (mg/L)
BOD5 (mg/L)
pH(S.U.)
NH3 - N (mg/L)
IDS (mg/L)
BOD5 (mg/L)
pH(S.U.)
NH3 - N (mg/L)
IDS (mg/L)
Benzene (ug/L)
BOD5 (mg/L)
Ethylbenzene (ug/L)
Naphthalene (ug/L)
NH3 - N (mg/L)
Oil and grease (mg/L)
DO (mg/L)
pH(S.U.)
TSS (mg/L)
Toluene (ug/L)
Xylene (ug/L)
Average
Effluent(a)
111
NA
10.8
1,080
134
NA
11.2
645
40.2
NA
3.4
1,200
117
NA
35.1
1,050
291
NA
8.28
1,740
381
NA
50
727
<7.62
77.7
<8.48
<15.2
<17.2
<1.27
7.9
NA
473
<5
<5
Range of Data
Points
1.1 - 1,650
6.9 -7.6
0.2 - 50
232 - 3,370
1 -2,150
6.0-7.6
0.2 - 50
227-1,620
2.5- 141
6.9-7.5
0.6- 10
105-2,080
9.2 - 342
6.7-7.6
2.6 - 85
624-1,340
0.9-3,100
6.8-7.6
0.7-37.5
211 -8,470
264 - 497
7.3
50
616-837
<5-97
3 - 1,250
<5 - 127
<5 - 361
O.03 - 171
<1 -3.5
0.270- 13.0
7.0-9.1
2.00-3,530
<5
<5
# of Data
Points
36
36
36
36
34
34
34
34
6
6
6
6
6
6
6
6
17
17
17
17
2
2
2
2
27
27
27
27
27
27
27
27
27
27
27
8-21
-------
Section 8.0 - Wastewater Characterization
Table 8-2 (Continued)
Airport
Baltimore/
Washington
International
(BWI)
Minneapolis-
St. Paul
International
(MSP)
Discharge Point(s)
306A and 307A -
Outfall 003 (runway,
terminal, and deicing
pad drainage)
007A and 703A -
Storm water runoff
(from taxiway,
terminal, and ramps)
010M and 01AM-
MotherLake and
Duck Lake drainage
(runways and
taxiway s)
020M, 030M,
03AM - Minnesota
River North and
Snelling Lake
drainage (terminal,
runway, and taxiway
drainage)
Parameter
BOD5 (mg/L)
EG (mg/L)
TKN (mg/L)
pH (S.U.)
BOD5 (mg/L)
EG (mg/L)
Petroleum
Hydrocarbons (mg/L)
TKN (mg/L)
pH(S.U.)
BOD5 (tons/mo)
BOD5 (mg/L)
BOD40 (mg/L)
PG (mg/L)
EG (mg/L)
COD (mg/L)
NH3 - N (mg/L)
NH3 (mg/L)
TKN (mg/L)
Oil and grease (mg/L)
DO (mg/L)
pH(S.U.)
P (mg/L)
TSS (mg/L)
Toluene (mg/L)
BOD5 (tons/mo)
BOD5 (mg/L)
BOD40 (mg/L)
PG (mg/L)
EG (mg/L)
COD (mg/L)
NH3 - N (mg/L)
NH3 (mg/L)
TKN (mg/L)
Oil and grease (mg/L)
DO (mg/L)
pH(S.U.)
P (mg/L)
TSS (mg/L)
Benzene (ug/L)
Ethylbenzene (ug/L)
Toluene (ug/L)
Xylene (ug/L)
Average
Effluent(a)
1,010
<10
12.8
NA
412
<10
1
2.25
NA
0.1
90.9
5.50
137
14.4
243
11.5
0.638
20.2
2.28
7.02
NA
0.329
15.3
0.002
14
497
319
313
95.8
763
19.4
0.671
48.4
3.90
4.82
NA
0.114
15.6
4.7
2.7
6.2
16.3
Range of Data
Points
23-2,510
<10
2-27
6.7-7.5
197-769
<10
1
2-3
6.7-7.1
0.001 -0.5
1 -694
2-10.0
9.4 - 596
4.1 -32.6
6- 1,880
0.09 - 50.6
0.002 - 5.27
0.3-75
0.8-7.7
1.8-9.7
7.1 -8.5
0.07-0.83
2-76
0.002
0.1 -83
5-2,140
8-676
3.2-1,660
2.6-561
2.9-4,320
0.48- 124
0.02-10.7
1.3-290
1.2-9.6
0.9-9.6
6.8-8.1
0.01 -0.41
5-54
0.1 - 12
0.2-5
0.2-23
3-30
# of Data
Points
4
4
4
4
4
4
1
4
4
10
10
4
5
3
10
10
10
9
7
10
10
8
10
1
18
18
12
14
10
18
18
18
18
17
18
18
16
18
4
4
6
4
8-22
-------
Section 8.0 - Wastewater Characterization
Table 8-2 (Continued)
Airport
Minneapolis-
St. Paul
International
(cont.)
Newark
International
(EWR)
Westchester
County
(HPN)
Tompkins
County
(ITH)
Discharge Point(s)
040M - Minnesota
River South drainage
area (terminal and
cargo areas)
006A - Storm water
from terminal
008A, 009A, 013A,
014A, 0146, 015A-
Storm water from
runway
001 A and 003 A -
Storm water from
ponds
004A, 008A, 009A -
Storm water from
buildings and
hangars
005 A, 006A, 007A -
Storm water from
taxiways and ditch
drainage
00 1M, 004M, 005M
- Storm water runoff
002M - Storm water
from deicing/fueling
pad
Parameter
BOD5 (tons/mo)
BOD5 (mg/L)
BOD40 (mg/L)
PG (mg/L)
EG (mg/L)
COD (mg/L)
NH3 - N (mg/L)
NH3 (mg/L)
TKN (mg/L)
Oil and grease (mg/L)
DO (mg/L)
pH(S.U.)
P (mg/L)
TSS (mg/L)
Benzene (ug/L)
Ethylbenzene (ug/L)
Toluene(ug/L)
Xylene (ug/L)
TOC (mg/L)
Hydrocarbons (mg/L)
pH(S.U.)
TSS (mg/L)
TOC (mg/L)
COD (mg/L)
Hydrocarbons (mg/L)
pH(S.U.)
TSS (mg/L)
BOD5 (mg/L)
PG (mg/L)
Oil and grease (mg/L)
pH(S.U.)
BOD5 (mg/L)
PG (mg/L)
Oil and grease (mg/L)
pH(S.U.)
BOD5 (mg/L)
PG (mg/L)
Oil and grease (mg/L)
pH(S.U.)
BOD5 (mg/L)
Oil and grease (mg/L)
pH(S.U.)
Average
Effluent(a)
10
641
26.0
853
27.9
1,250
44.2
8.18
77.5
15.8
4.72
NA
0.378
32.8
0.45
1.7
18
1.2
16
2.45
NA
11.3
83.5
189
<1.98
NA
<12.5
2.82
32.8
5
NA
4.92
0.134
5
NA
2.53
0.213
5
NA
<3
<0.5
NA
Range of Data
Points
0.001 -41
5- 1,210
18-34
137- 1,830
1.7-54.2
37-3,170
0.04-172
0.003 - 42.7
1 -235
2.8-67
1.9-7.6
8.2-8.7
0.18-0.73
10-67
0.3-0.6
1.7
1.8-34.6
1.2
9-23
1 -3.9
6.1 -7.0
3-38
7-1,120
49-338
0.4-8.8
5.1 -7.5
<2-64
2-7.2
0.05 - 220
5
6.9-8.6
2-37
0.05-0.82
5
6.3-8.8
2-8.4
0.05-1.3
5
6.0-8.0
<3-3
O.5-0.5
6.8-7.5
# of Data
Points
6
6
2
4
4
6
6
6
6
6
6
6
6
6
2
1
2
1
7
7
7
7
32
7
39
39
39
14
12
14
14
21
18
21
21
19
17
19
19
18
7
7
8-23
-------
Section 8.0 - Wastewater Characterization
Table 8-2 (Continued)
Airport
Syracuse
Hancock
International
(SYR)
Nashville
International
(BNA)
Salt Lake City
International
(SLC)
Discharge Point(s)
001M, 003M,
004M, 005M,
006M, 007M -
Storm water runoff
002G - Effluent from
treatment basin
001 A, 002A, 003 A -
Storm water
discharge from
terminal, runway,
apron, and cargo
areas
Parameter
BOD5 (mg/L)
Oil and grease (mg/L)
pH (S.U.)
TSS (mg/L)
NH3 - N (mg/L)
Benzene (ug/L)
BOD5 (mg/L)
HEM (mg/L)
COD (mg/L)
DO (mg/L)
pH(S.U.)
TSS (mg/L)
BOD5 (mg/L)
Nitrate/Nitrite (mg/L)
Oil and grease (mg/L)
COD (mg/L)
pH(S.U.)
Average
Effluent(a)
<334
<6.18
NA
<11.5
7.3
<2.5
38.1
<6.71
<69.6
8.64
NA
32.7
332
4.73
9
835
NA
Range of Data
Points
<4 - 3,500
<4-26
6.8-8.2
<4- 19
0.17-24.3
<1 -<5
3-98
<1 - 14
<20-130
6.4- 11.9
7.2-8.6
18-55
11 -1,050
0.9-9
8-10
104 - 3,880
6.6-9.5
# of Data
Points
30
36
36
6
14
12
7
7
7
7
7
7
11
5
2
12
21
(a) Data represent only the 1997-1998 Deicing Season.
Key:
BOD5 - 5-day biochemical oxygen demand.
BOD40 - 40-day biochemical oxygen demand.
COD - Chemical oxygen demand.
DO - Dissolved oxygen.
EG - Ethylene glycol.
HEM - Hexane extractable material (i.e., oil and grease).
NA - Not applicable.
NH3 - Ammonia - un-ionized.
NH3-N - Ammonia as Nitrogen.
P - Phosphorus.
PG - Propylene glycol.
IDS - Total dissolved solids.
TKN - Total kjeldahl nitrogen.
TSS - Total suspended solids.
< - Not detected or maximum concentration.
8-24
-------
Section 8.0 - Wastewater Characterization
Table 8-3
Standard Analytical Methods for Parameters Included in EPA's
Airport Deicing Sampling Program
Parameter
Ammonia as nitrogen
Biochemical oxygen demand (5-day)
Total organic carbon
Glycols
Metals (including potassium)
Volatile organic compounds
Semivolatile organic compounds (including
tolyltriazoles)
Hexane extractable material
Silica-gel treated hexane extractable material
Whole effluent toxicitv:
Fathead Minnow (Pimephales promelas)
Cladoceran (Ceriodaphnia dubid)
Method Number
350.2
405.1
415.1
624
1620
1624C
1625C
1664
1664
NA
NA - Method number not applicable. Analytical methods per Methods for Measuring the Acute Toxicitv of Effluents
and Receiving Water to Fresh Water and Marine Organisms. U.S. EPA, August 1993.
8-25
-------
Section 8.0 - Wastewater Characterization
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
Pollutant
Code
P038
P086
P066
P068
P065
Analyte
VOLATILE ORGANICS Og/L)
ETHYLBENZENE
TOLUENE
M- + P-XYLENE
SEMIVOLATILE ORGANICS Og/L)
N-HEXADECANE
BIS(2-ETHYLHEXYL) PHTHALATE
DI-N-BUTYL PHTHALATE
N-DODECANE
5-METHYL- 1 H-BENZOTRIAZOLE
PHENOL
N-TETRADECANE
GLYCOLS (mg/L)
ETHYLENE GLYCOL
DIETHYLENE GLYCOL
PROPYLENE GLYCOL
Type I Deicing Fluids
(50% Solution)
Ethylene
Glycol-
Based Fluid
ND(IOO)
ND(IOO)
ND(IOO)
ND(500)
7,200
100
3,000
2,000
ND(500)
ND(500)
NA
NA
NA
Propylene
Glycol-
Based Fluid
580
620
2,800
ND(IOO)
350
ND(IOO)
ND(IOO)
2,200,000
ND(IOO)
ND(IOO)
NA
NA
NA
Albany International Airport
Small
Lagoon
ND(10)
ND(10)
ND(10)
ND(10)
>200
ND(10)
ND(10)
>2,000
110
ND(10)
ND(10)
ND(5.0)
2,700
Composite of
Large Lagoon
and Tank
NA
NA
NA
ND(10)
ND(10)
ND(10)
ND(10)
2,200
64
ND(10)
ND(10)
ND(5.0)
1,200
Raw Wastewater Samples
Kansas City
International
Airport
NA
NA
NA
ND(10)
ND(10)
ND(10)
ND(10)
17,000
93
ND(10)
3,200
>20,000
16,000
Bradley
International
Airport
NA
NA
NA
110
ND(IOO)
ND(IOO)
ND(1,000)
90,000
280
140
3,000
15,000
160,000
Greater
Rockford
Airport
NA
NA
NA
ND(10)
ND(10)
ND(10)
ND(10)
120
ND(10)
ND(10)
ND(10)
ND(5.0)
ND(5.0)
Storm Water
Outfall
Samples
Bradley
International
Airport
NA
NA
NA
ND(10)
ND(10)
ND(10)
ND(10)
200
ND(10)
ND(10)
ND(10)
ND(5.0)
180
oo
to
ND - Analyte not detected (followed by detection limit).
NA - Not analyzed.
> - Minimum concentration.
-------
Section 8.0 - Wastewater Characterization
Table 8-4 (Continued)
Priority
Pollutant
Code
P114
P115
P118
P119
P120
P122
P123
P125
P126
P127
Analyte
METALS Og/L)
ALUMINUM
ANTIMONY
ARSENIC
BARIUM
BORON
CADMIUM
CALCIUM
CHROMIUM
COPPER
IRON
LEAD
MAGNESIUM
MANGANESE
MERCURY
POTASSIUM
SELENIUM
SILVER
SODIUM
THALLIUM
TIN
TITANIUM
VANADIUM
Type I Deicing Fluids
(50% Solution)
Ethylene
Glycol-
Based Fluid
230
ND(20)
24
3.0
1,400
240
1,100
3.5
20
230
53
ND(89)
ND(l.O)
NQ
20,000
NQ
ND(5.0)
36,000
ND(l.O)
1,100
ND(3.0)
ND(ll)
Propylene
Glycol-
Based Fluid
120
91
360
24
36
6.7
2,000
ND(1)
44
670
110
ND(70)
40
NQ
NA
890
ND(4.0)
24,000
330
1,300
ND(4.0)
ND(10)
Albany International Airport
Small
Lagoon
530
ND(2.0)
ND(l.O)
89
ND(26)
1.0
38,000
2.7
ND(9.0)
3,500
6.6
7,100
1,100
ND(0.2)
64,000
ND(2.0)
ND(5.0)
62,000
ND(l.O)
12
6.4
ND(10)
Composite of
Large Lagoon
and Tank
1,100
ND(2.0)
ND(l.O)
86
ND(26)
1.4
36,000
3.6
14
9,200
9.5
7,400
1,000
ND(0.2)
57,000
ND(2.0)
ND(5.0)
63,000
ND(l.O)
12
11
ND(10)
Raw Wastewater Samples
Kansas City
International
Airport
860
ND(2.0)
2.8
60
ND(26)
3.4
34,000
5.0
14
1,200
15
2,500
170
ND(0.2)
13,000
ND(20)
ND(5.0)
11,000
ND(l.O)
20
68
ND(10)
Bradley
International
Airport
1,100
ND(20)
ND(l.O)
36
ND(26)
11
33,000
7.2
44
3,400
50
2,000
140
0.29
ND(900)
ND(20)
6.6
10,000
ND(10)
180
44
16
Greater
Rockford
Airport
270
ND(2.0)
3.4
31
ND(26)
ND(l.O)
14,000
3.7
9.2
810
4.3
3,000
360
ND(0.2)
64,000
ND(2.0)
ND(5.0)
7,900
ND(l.O)
ND(5.0)
9.1
ND(10)
Storm Water
Outfall
Samples
Bradley
International
Airport
69
2.3
ND(l.O)
91
220
ND(l.O)
41,000
ND(l.O)
ND (9.0)
7,100
ND (2.0)
12,000
1,600
ND (0.2)
ND (900)
ND (20)
ND(5.0)
75,000
ND(l.O)
ND (4.0)
ND(5.0)
ND(10)
oo
I
to
ND - Analyte not detected (followed by detection limit).
NQ - Analyte not quantified due to matrix interference.
-------
Section 8.0 - Wastewater Characterization
Table 8-4 (Continued)
Priority
Pollutant
Code
P128
Analyte
ZINC
CLASSICAL WET CHEMISTRY (mg/L)
AMMONIA AS NITROGEN
BIOCHEMICAL OXYGEN DEMAND (5-DAY)
TOTAL ORGANIC CARBON (TOC)
SILICA-GEL TREATED HEXANE EXTRACTABLE
MATERIAL
HEXANE EXTRACTABLE MATERIAL
WHOLE EFFLUENT TOXICITY (LC 50, endpoint
(%))
CERIODAPHNIA DUBIA (48-HOUR ACUTE)
PIMEPHALES PROMELAS (96-HOUR ACUTE)
Type I Deicing Fluids
(50% Solution)
Ethylene
Glycol-
Based Fluid
190
3.0
NA
410,000
NA
NA
NA
NA
Propylene
Glycol-
Based Fluid
440
5.4
NA
210,000
NA
NA
NA
NA
Albany International Airport
Small
Lagoon
110
88
12,000
2,400
ND(5.0)
ND(6.0)
NA1
NA1
Composite of
Large Lagoon
and Tank
130
84
9,800
2,500
ND(5.0)
ND(6.0)
NA1
NA1
Raw Wastewater Samples
Kansas City
International
Airport
140
3.9
5,100
3,000
6.0
10
58
40
Bradley
International
Airport
340
23
39,000
35,000
65
170
1.2
3.1
Greater
Rockford
Airport
45
46
>7.3
12
ND(6.0)
100
NA1
NA1
Storm Water
Outfall
Samples
Bradley
International
Airport
ND(10)
1.1
61
26
ND(5.0)
ND(5.0)
>100
>100
oo
I
to
oo
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
Table 8-5
Analytical and Toxicity Data Provided by Fluid Formulators
for Type I Aircraft Deicing Fluids
Parameter
Ethylene glycol (% weight)
Propylene glycol (% weight)
Chemical oxygen demand (mg O2/mg of fluid)
Percentage biodegradation
Rainbow trout (LC50, 96-hour)(mg/L)
Fathead minnows (LC50, 96-hour)(mg/L)
Daphnia magna (LCW, 48-hour)(mg/L)
TJCAR™ Aircraft Deicing Fluid
Concentrate
92
N/A
1.14
69 (5-day)
85 (1 0-day s)
96 (20-days)
17,100
22,000
NA
Octaflo Concentrate
N/A
88
NA
61 (7-days)
84 (1 4-day s)
93 (21 -days)
NA
1,250
750
N/A - Not applicable.
NA - Data not available.
8-29
-------
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents
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,
9-1
-------
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents
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
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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 LC50 for ethylene glycol and propylene glycol occurred at
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.
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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).
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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.
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.
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.
Immunological and lymphoreticular - No evidence is currently available
that links immunological effects to inhalation of either ethylene glycol or
propylene glycol.
Neurological - No evidence is currently available that links neurological
effects to inhalation of either ethylene glycol or propylene glycol.
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.
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.
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.
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• 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.
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.
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.
Immunological and lymphoreticular - No evidence is currently available
that links immunological effects to ingestion of either ethylene glycol or
propylene glycol.
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
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propylene glycol may also result in neurological effects in allergic
individuals, including stupor and repetitive convulsions.
• 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.
• 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.
• 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.
• 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.
Death - No evidence is currently available that links death to dermal
exposure of either ethylene glycol or propylene glycol.
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
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infant's problem could not be determined, propylene glycol cannot be ruled
out as the potential harmful agent.
• 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."
• Neurological - No evidence is currently available that links neurological
effects in humans or animals to dermal exposure to ethylene glycol or
propylene glycol.
• 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.
• 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.
• Genotoxic - No evidence is currently available that links genotoxic effects
in humans or animals to dermal exposure to ethylene glycol or propylene
glycol.
• 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
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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
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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:
• Ethylene glycol or propylene glycol;
• Water;
• Surfactants (wetting agents);
• Corrosion inhibitors (including flame retardants);
• pH buffers;
• Dyes;
• 1,4-Dioxane; and
• 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
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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).
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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-lH-benzotriazole (common name: tolyltriazole or
TTZ), although IH-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
Bluegill sunfish
(Lepomis macrochirus)
Water flea (Daphnia
magna)
Duration
96-hLC50
48-h LC50
LC50 for TTZ
(mg/L)
31
74
LC50 for Ethylene
Glycol (mg/L)
27,540
46,300 - 54,700
LC50 for Propylene
Glycol (mg/L)
Not available
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.
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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
Benzotriazole
Tolyltriazole
5-min. EC50 (mg/L)
41
6
15-min. EC50 (mg/L)
42
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 LD50 of 1,230 mg/kg for rats (14).
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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
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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
Fathead Minnow
(Pimephales promelas)
Rainbow Trout
(Oncorhynchus mykiss)
Water Flea (Daphnia
magna)
Water Flea (Daphnia
magna)
Duration and
Endpoint
96-hLC50
96-h LC50
48-h EC50
48-hLC50
Type I EG-Based Deicing Fluid
Concentration (mg/L)
22,000
17,100
44,000
NA
Type I PG-Based Deicing
Fluid Concentration (mg/L)
1,250
NA
NA
750
Reference: (19,20).
NA - Not available.
LC50 - Median lethal concentration that kills 50% of the test organisms.
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
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were collected under laboratory conditions in compliance with SAE specifications and not under
actual field conditions.
Species
Fathead Minnow
(Pimephales promelas)
Rainbow Trout
(Oncorhynchus mykiss)
Water Flea (Daphnia
magna)
Duration and
Endpoint
96-h LC50
96-hLC50
48-h LC50
Type IV EG-Based
Deicing/Anti-icing Fluid
Concentration (mg/L)
370
380
630
Type IV PG-Based
Deicing/Anti-icing Fluid
Concentration (mg/L)
NA
NA
975
Reference: (19,20).
NA - Not available.
LC50 - Median lethal concentration that kills 50% of the test organisms.
In general, Type I ADFs, regardless of chemical basis, may be considered
"relatively harmless" per the U.S. Fish and Wildlife Service Classification System1. In contrast,
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.,
'Although EPA does not use such a system, the U.S. Fish and Wildlife Classification System for Acute Exposures
defines "relatively harmless" as any chemical with an LC50 above 1,000 mg/L (3).
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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., LC50 > 1,000 mg/L).
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.
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n
PG - Propylene Glycol
PGonly
Fully Formulated
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
Toxicitv 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).
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Section 9.0 - Toxicity of Deicing/Anti-Icing Agents
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 anti-
freeze, 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 -10° C (23). The freezing point of a
40% diethylene glycol and 60% water mixture is -18° C, while that of a 50/50 mixture is -28° C
(the freezing point of a 50/50 mixture of ethylene glycol and water is -35° 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).
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Section 9.0 - Toxicity of Deicing/Anti-Icing Agents
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 effect-
level 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
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Section 9.0 - Toxicity of Deicing/Anti-Icing Agents
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 -88.5° 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.
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Section 9.0 - Toxicity of Deicing/Anti-Icing Agents
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:
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Section 9.0 - Toxicity of Deicing/Anti-Icing Agents
NH2CONH2 (urea) + 1H,O => NH^ + NH^ + HCO3 (1)
NH4+ + l.5O2 => NO2 + H2O + 2H+ (2)
NO2 + 0.5O2 => NO3 (3)
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
Barilius barna
Tilapia mossambica
Leuciscus idus melanotus
Water Flea (Daphnia magna)
Mosquito (Aedes aegypti)
Freshwater snail (Helisoma
trivolvis)
Rat
Mouse
Duration
96-h LC50
96-h LC50
48-h LC50
24-h EC50
4-h LC50
24-hLC50
24-h LC50
24-hLC50
LD50 (oral)
LD50 (subcutaneous)
LD50 (intravenous)
Concentration/Dose
>9, 100 mg/L
22,500 mg/L
> 10,000 mg/L
> 10,000 mg/L
60,000 mg/L
30,060 mg/L (adults)
18,255 mg/L (juvenile)
14,241 mg/L (egg)
14,300 mg/kg
8,200 mg/kg
4,600 mg/kg
Sources: References (30, 31).
LC50 - Median lethal concentration that kills 50% of the test organisms.
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.
LD50 - Median lethal dose that kills 50% of the test organisms.
> - Minimum concentration.
Ammonia in its un-ionized form is one of the urea byproducts that may have
significant adverse aquatic effects and reported LC50 values in the range of 1 to 10 mg/L (31).
Aquatic toxicity data for ammonia in its un-ionized form are summarized below.
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Section 9.0 - Toxicity of Deicing/Anti-Icing Agents
Species
Fathead minnow (Pimephales
promelas)
Goldfish (Carassius auratus)
Rainbow trout (Oncorhynchus
mykiss)
Water flea (Daphnia magna)
Water flea (Daphnia pulex)
Duration
96-h LC50
24-96-h LC50
24-h LC50 (fertilized egg)
24-h LC50 (0-50 days old)
24-h LC50 (85 days old)
24-h LC50 (adults)
48-h LC50(static test)
48-h LC50 (static test)
Concentration (mg/L)
0.73-3.4;
8.2 (hard water)
2-2.5
>3.58
>3.58
0.068
0.097
189
187
Source: Reference (23).
LC50 - Median lethal concentration that kills 50% of the test organisms.
> - 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.
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Section 9.0 - Toxicity of Deicing/Anti-Icing Agents
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
Rat
Duration
LD50 (oral)
LD50 (intraperitoneal)
LD50 (subcutaneous)
LD50 (intravenous)
LD50 (intramuscular)
Dose (mg/kg)
4,700
5,010
2,800
3,260
3,300
Source: Reference (30).
LD50 - Median lethal dose that kills 50% of the test organisms.
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.
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Section 9.0 - Toxicity of Deicing/Anti-Icing Agents
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
Fathead minnow (Pimephales
promelas)
Rainbow trout (Oncorhynchus
mykiss)
Water flea (Daphnia magna)
Rat
Duration
LC50 (duration unknown)
7-dLC50
96-hLC50
48-h LC50
LD50
Concentration/Dose
>500 mg/L
>l,500mg/L
>2, 100 mg/L
>3,000 mg/L
>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).
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Section 9.0 - Toxicity of Deicing/Anti-Icing Agents
Species
Rainbow trout (Oncorhynchus mykiss)
Water flea (Daphnia magna)
Rat
Duration
96-h LC50
48-h LC50
LD50 (oral)
LD50 (dermal)
4-h LCTO (inhalation)
Concentration/Dose
> 1,000 mg/L
> 1,000 mg/L
>5,000 mg/L
>5,000 mg/kg
4.6 mg/L
Source: Reference (31).
LC50 - Median lethal concentration that kills 50% of the test organisms.
LD50 - Median lethal dose that kills 50% of the test organisms.
> - 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
Water flea (Daphnia magna)
Fathead minnow (Pimephales promelas)
Rat
Mouse
Mouse
Duration
48-h LC50
24-hLC50
LD50 (oral)
LD50 (subcutaneous)
LDW (intravenous)
Concentration/Dose
2,400 mg/L
2,750 mg/L
3,530 mg/kg
8,000 mg/kg
335 mg/kg
Source: Reference (31).
LC50 - Median lethal concentration that kills 50% of the test organisms.
LD50 - Median lethal dose that kills 50% of the test organisms.
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Section 9.0 - Toxicity of Deicing/Anti-Icing Agents
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):
LD50 (oral) = 1 1,200 mg/kg; and
(intraperitoneal) = 807 mg/kg.
Toxicity data obtained from a sodium formate deicer manufacturer are summarized below.
Species
Water flea (Daphnia magna)
Zebra fish
Rat
Duration
24-hEC50
48-h EC50
24-hEC0
48-h EC0
96-hLC50
LD50(oral)
4-h LC50 (inhalation)
Concentration/Dose
4,800 mg/L
4,400 mg/L
3,300 mg/L
3,200 mg/L
100 mg/L
>2,000 mg/L
>670 mg/L
Source: Reference (31).
LC50 - Median lethal concentration that kills 50% of the test organisms.
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.
LD50 - Median lethal dose that kills 50% of the test organisms.
> - 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).
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Section 9.0 - Toxicity of Deicing/Anti-Icing Agents
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.
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Section 9.0 - Toxicity of Deicing/Anti-Icing Agents
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 TDCN T105681
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.
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Section 9.0 - Toxicity of Deicing/Anti-Icing Agents
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-I Mice (Abstract).
(DCN T10569).
27. Aldrich Catalog Handbook of Fine Chemicals. 1996-1997.
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Section 9.0 - Toxicity of Deicing/Anti-Icing Agents
28. U.S. Environmental Protection Agency. Draft Cleaner Technologies Substitutes
Assessment TCTSAV 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 (SIPS). 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.
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Section 9.0 - Toxicity of Deicing/Anti-Icing Agents
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, P.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, TJ. 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.
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Section 9.0 - Toxicity of Deicing/Anti-Icing Agents
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 3 04, 1981.
65. Spillane, L. et al. "Multiple Cranial Nerve Deficits after Ethylene Glycol
Poisoning." Annals of Emergency Medicine. Volume 20(2). 1991.
9-34
-------
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents
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, RJ. 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.
9-35
-------
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents
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.
9-36
-------
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents
Table 9-1
Acute and Chronic Toxicity Data for Pure Glycols for Aquatic Species
Species
Rainbow Trout
(Oncorhynchus
mykiss)
Fathead
Minnow
(Pimephales
promelas)
Goldfish
(Carassius
auratus)
Clawed Frog
(Xenopus
laevis)
Water Flea
(Daphnia
magnet)
Duration and
Endpoint
24-hLC50
48-h LC50
72-hLC50
96-h LC50
24-hLC50
48-h LC50
48-hLC50
72-h LC50
96-hLC50
96-hLC50
96-h NOEC
(mortality)
7-d NOEC
(mortality)
7-d NOEC
(growth)
24-h LC50
48-hLC50
24-h LC50
24-h EC50
(immobilization)
48-h LC50
Life
Stage
0.64 g
0.64 g
0.64 g
0.3 -5g
0.3 g
0.3 g
7dold
0.3 g
0.3- 0.4 g
7dold
7dold
7dold
7dold
6.2cm
3.3 g
3-4 weeks
old
<24 h old
(0.19mg)
<24 h old
<24 h old
(0.19mg)
Temp.
(°C)
12
12
12
12-15
22
22
25
22
21 -23
25
25
25
25
20
20.0-
20.5
20
20
20
Concentration of
Pure Ethylene
Glycol (mg/L)
65,100(12)
54,500 (12)
54,500 (12)
50,800 (12)
45,600 (34)
17,800 (34)
22,810(35)
24,591 (35)
41,000(36)
83,400 (12)
52,300 (12)
81,950(37)
52,300 (12)
50,400 (12)
57,000 (38)
72,860 (37)
39,140(37)
32,000 (37)
15,380(37)
>5,000 (39)
19,350(35)
15,667(35)
80,600 (12)
48,582 (40)
54,700 (12)
46,300(13)
51,100(13)
Concentration of
Pure Propylene
Glycol (mg/L)
79,700 (12)
79,700 (12)
51,600(12)
51,600(12)
45,600 (34)
42,380 (35)
37,067 (35)
77,800 (12)
54,000 (12)
> 62,000 (37)
51,400(12)
51,400(12)
55,770 (37)
52,930 (37)
< 11,530 (37)
< 11,530 (37)
>5,000 (39)
18,700(35)
24,285 (35)
70,700 (12)
> 10,000 (41)
43,500 (12)
Reference
Wardetal. 1992(12)
Wardetal. 1992(12)
Wardetal. 1992(12)
Wardetal. 1992(12)
Mayer and Ellersieck
1986(34)
Beak Consultants 1995
(35)
Johnson and Finley
1980(36)
Wardetal. 1992(12)
Wardetal. 1992(12)
Pillardl995(37)
Wardetal. 1992(12)
Wardetal. 1992(12)
Mayesetal. 1983(38)
Pillardl995(37)
Pillardl995(37)
Pillardl995(37)
Pillardl995(37)
Bridie et all 979 (39)
Beak Consultants 1995
(35)
Wardetal. 1992(12)
Lilmsetall995(40)
Kuhnetall989(41)
Wardetal. 1992(12)
Cowgilletall985(13)
9-37
-------
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents
Table 9-1 (Continued)
Species
Ceriodaphnia
dubia
Green Algae
(Selenastrum
capricornutum)
Duckweed
(Lemna minor)
Duration and
Endpoint
48-h LC50
48-h NOEC
7-d NOEC
(mortality)
7-d NOEC
(reproduction)
24-h EC50
48-h EC50
72-h EC50
96-h EC50
14-dEC50
96-h IC50
96-h IC25
96-h LOEC
96-h NOEC
96-h IC25
96-h IC25 (frond
growth)
96-h LOEC
(frond growth)
96-h IC25
(chlorophyll)
96-h LOEC
(chlorophyll)
96-h IC25
(pheophytin)
Life
Stage
<24 h old
<24 h old
<24 h old
<24 h old
1,000
cells/mL
1,000
cells/mL
1,000
cells/mL
1,000
cells/mL
1,000
cells/mL
NR
NR
NR
NR
NR
5 plants/
beaker
5 plants/
beaker
5 plants/
beaker
5 plants/
beaker
5 plants/
beaker
Temp.
(°C)
25
25
25
25
24
24
24
24
24
25
25
25
25
25
25
25
25
25
25
Concentration of
Pure Ethylene
Glycol (mg/L)
34,440 (37)
24,000 (37)
24,000 (37)
8,590 (37)
3,469 (35)
<6,400(12)
13,100(12)
<6,400(12)
7,900 (12)
18,200(12)
13,067(35)
8,828 (35)
13,925(35)
6,963 (35)
5,336 (42)
17,115(42)
10,000 (42)
19,848(42)
20,000 (42)
16,470 (42)
Concentration of
Pure Propylene
Glycol (mg/L)
18,340(37)
13,020(37)
29,000 (37)
13,020(37)
5,200 (12)
34,100(12)
24,200 (12)
19,000(12)
18,100(12)
20,690 (35)
1,516(35)
126 (35)
37 (35)
20,800 (42)
12,000 (42)
5,000 (42)
21,882(42)
20,000 (42)
12,000 (42)
Reference
Pillardl995(37)
Pillardl995(37)
Pillardl995(37)
Pillardl995(37)
Beak Consultants 1995
(35)
Wardetal. 1992(12)
Wardetal. 1992(12)
Wardetal. 1992(12)
Wardetal. 1992(12)
Wardetal. 1992(12)
Beak Consultants 1995
(35)
Beak Consultants 1995
(35)
Beak Consultants 1995
(35)
Beak Consultants 1995
(35)
DuFresne and Pillard
1995(42)
DuFresne and Pillard
1995(42)
DuFresne and Pillard
1995(42)
DuFresne and Pillard
1995(42)
DuFresne and Pillard
1995(42)
DuFresne and Pillard
1995(42)
9-38
-------
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents
Table 9-1 (Continued)
Species
Duckweed
(cont.)
Sheepshead
minnow
(Cyprinodon
variegatus)
Mysid
(Mysidopsis
bahia)
Marine algae
(Skeletonema
costatum)
Duration and
Endpoint
96-h LOEC
(pheophytin)
24-h LC50
48-h LC50
72-h LC50
96-h LC50
24-h LC50
48-h LC50
72-h LC50
96-h LC50
24-h EC50
48-h EC50
72-h EC50
96-h EC50
14-dEC50
Life
Stage
5 plants/
beaker
0.74 g
0.74 g
0.74 g
0.74 g
2.4 mg
2.4 mg
2.4 mg
2.4 mg
1,000
cells/mL
1,000
cells/mL
1,000
cells/mL
1,000
cells/mL
1,000
cells/mL
Temp.
(°C)
25
22
22
22
22
22
22
22
22
20
20
20
20
20
Concentration of
Pure Ethylene
Glycol (mg/L)
40,000 (42)
81,700(12)
74,800 (12)
39,100(12)
27,600 (12)
73,900 (12)
52,600 (12)
43,600 (12)
34,200 (12)
<6,900(12)
23,900 (12)
29,900 (12)
44,200 (12)
<5,300(12)
Concentration of
Pure Propylene
Glycol (mg/L)
20,000 (42)
63,500 (12)
52,500 (12)
35,900 (12)
23,800 (12)
31,000(12)
27,300 (12)
23,400 (12)
18,800(12)
31,500(12)
19,000(12)
19,300(12)
19,100(12)
<5,300(12)
Reference
DuFresne and Pillard
1995(42)
Wardetal. 1992(12)
Wardetal. 1992(12)
Wardetal. 1992(12)
Wardetal. 1992(12)
Wardetal. 1992(12)
Wardetal. 1992(12)
Wardetal. 1992(12)
Wardetal. 1992(12)
Wardetal. 1992(12)
Wardetal. 1992(12)
Wardetal. 1992(12)
Wardetal. 1992(12)
Wardetal. 1992(12)
LC50 - Median lethal concentration that kills 50% of the test organisms.
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.
IC25 - Concentration that inhibits growth and reproduction in 25% of the test organisms.
LOEC - Lowest concentration at which effects were observed.
( ) - Reference for the data provided.
9-39
-------
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents
Table 9-2
Additional Acute and Chronic Toxicity Data Sources for Pure Glycols
Pure Glycol Type
Ethylene Glycol
Species
Rainbow trout
(Oncorhynchus mykiss)
Fathead minnow (Pimephales
promelas)
Bluegill sunfish (Lepomis
macrochirus)
Guppy (Poecillia reticulatd)
Clawed frog (Xenopus laevis)
Water flea (Daphnia magna)
Water flea (Daphnia pulex)
Ceriodaphnia dubia
Streptocephalus probscideus
Chironomus tentans
Crayfish (Procambarus sp.)
Rotifer (Brachionus
calciflorus)
Ciliated protozoan
(Colpidium campylum)
Reference
Beak Consultants 1995 (35)
Mayesetal. 1983(38)
Beak Consultants 1995 (35)
Mayer and Ellersieck 1986
(34)
Abdelgham et al. 1990(12)
Konemannl981 (43)
deZwart and Slooff 1987 (44)
Gersichetal. 1986(45)
Hermensetal. 1984(46)
Callejaetal. 1994(47)
Bringmann and Kuhn 1 977
(48)
Lilmsetal. 1995(40)
Cowgilletal. 1985(13)
Pillardl995(37)
Beak Consultants 1995 (35)
Callejaetal. 1994(47)
Aeroports de Montreal 1 995
(49)
Abdelgham et al. 1990(12)
Beak Consultants 1995 (35)
Callejaetal. 1994(47)
Beak Consultants 1995 (35)
9-40
-------
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents
Table 9-2 (Continued)
Pure Glycol Type
Ethylene Glycol (con't.)
Propylene Glycol
Species
Green algae (Selenastrum
capricornutum)
Criptomonad (Chilomonas
paramecium)
Brine shrimp (Artemia salina)
Shrimp (Crangon crangon)
Polychaeta (Ophrytrocha
labronica)
Rainbow trout
(Oncorhynchus mykiss)
Fathead minnow (Pimephales
promelas)
Water flea (Daphnia magna)
Ceriodaphnia dubia
Green algae (Selenastrum
capicornutum)
Duckweed (Lemna minor)
Harpaticoid copepod (Nitocra
spinipes)
Reference
Aeroports de Montreal and
Analexlnc. 1994(50)
Ward and Boen 1993(51)
Price etal. 1974(52)
Blackmanl974(53)
Akesson 1970(54)
Majewski et al. 1978(55)
Pillardl995(37)
Kuhnetal. 1989(41)
Pillardl995(37)
Dufresne andPillard 1995 (42)
Dufresne andPillard 1995 (42)
Tarkpeaetal. 1986(56)
( ) - Reference for the data provided.
9-41
-------
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents
Table 9-3
Human Toxicity Data for Pure Ethylene Glycol and Propylene Glycol
Exposure
Type
Inhalation
Oral
(ingestion)
Health Effect
Exposure/
Duration/
Frequency
NOAEL
LOAEL and
Seriousness
Reference
Ethylene Glycol
Systemic -
Respiratory
Systemic -
Hematological
Systemic - Renal
Neurological
1 5 min.
30 days (20-
22 hrs/day)
30 days (20-
22 hrs/day)
30 days (20-
22 hrs/day)
19mg/L
19mg/L
55 mg/L (less
serious)
1 9 mg/L (less
serious)
Wills etal. 1974(57)
Wills etal. 1974(57)
Wills etal. 1974(57)
Wills etal. 1974(57)
Ethylene Glycol
Death
Systemic -
Metabolism
Systemic -
Respiratory
Once
Once
Once
Once
Once
Once
Once
Once
Once
Once
Once
Once
7,070 mg/kg/d
(serious)
4,071 mg/kg/d
(serious)
2,379 mg/kg/d
(serious)
1,559 mg/kg/d
(serious)
4,3 32 mg/kg/d
(serious)
7,070 mg/kg/d
(serious)
11, 23 8 mg/kg/d
(serious)
3,171 mg/kg/d
(serious)
7,600 mg/kg/d
(serious)
4,071 mg/kg/d
(serious)
12,83 9 mg/kg/d
(serious)
7,070 mg/kg/d
(less serious)
Gordon and Hunter
1982(58)
Slew etal. 1975(59)
Walton 1978 (60)
Verschueren 1983 (23)
Cheng etal. 1987(61)
Gordon and Hunter
1982(58)
Heckerlmgl987(62)
Parry and Wallach
1974(63)
Peterson et al. 1981
(64)
Slew etal. 1975(59)
Spillane et al. 1991
(65)
Gordon and Hunter
1982(58)
9-42
-------
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents
Table 9-3 (Continued)
Exposure
Type
Oral (cont.)
Health Effect
Systemic -
Cardiovascular
Systemic - Renal
Systemic -
Gastrointestinal
Neurological
Exposure/
Duration/
Frequency
Once
Once
Once
Once
Once
Once
Once
Once
Once
Once
Once
Once
Once
Once
Once
Once
Once
Once
Once
NOAEL
LOAEL and
Seriousness
7,070 mg/kg/d
(serious)
3,171 mg/kg/d
(serious)
4,071 mg/kg/d
(serious)
7,070 mg/kg/d
(serious)
11, 23 8 mg/kg/d
(serious)
2,7 14 mg/kg/d
(serious)
3,171 mg/kg/d
(serious)
7,600 mg/kg/d
(serious)
4,071 mg/kg/d
(serious)
12,83 9 mg/kg/d
(serious)
12,83 9 mg/kg/d
(serious)
9,771 mg/kg/d
(serious)
4,3 32 mg/kg/d
(serious)
7,070 mg/kg/d
(less serious)
11, 23 8 mg/kg/d
(serious)
2,7 14 mg/kg/d
(serious)
3,171 mg/kg/d
(serious)
4,071 mg/kg/d
(serious)
12,83 9 mg/kg/d
(serious)
Reference
Gordon and Hunter
1982(58)
Parry and Wallach
1974(58)
Slewetal. 1975(59)
Gordon and Hunter
1982(58)
Heckerlmgl987(62)
Mallyaetal. 1986(66)
Parry and Wallach
1974(63)
Peterson et al. 1981
(64)
Slewetal. 1975(59)
Spillane et al. 1991
(65)
Spillane et al. 1991
(65)
Blakeley et al. 1993
(67)
Cheng etal. 1987(61)
Gordon and Hunter
1982(58)
Heckerlmgl987(62)
Mallyaetal. 1986(66)
Parry and Wallach
1974(63)
Slewetal. 1975(59)
Spillane et al. 1991
(65)
9-43
-------
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents
Table 9-3 (Continued)
Exposure
Type
Dermal
Health Effect
Exposure/
Duration/
Frequency
NOAEL
LOAEL and
Seriousness
Reference
Propylene Glycol
Systemic -
Hematological
Systemic -
Respiratory
Systemic -
Cardiovascular
Systemic -
Metabolism
Systemic -
Dermal
Systemic -
Dermal
Immunological/
Lymphoreticular
Neurological
5 days
(Ix/day)
70 hr
(>lx/d)
70 hr
(>lx/d)
70 hr
(>lx/d)
20-24 hours
48 hours
once
48 hours
once
7 days
(2x/day)
48 hours
once
48 hours
once
48 hours
once
2 1-22 days
20-24 hours
70 hours
(>lx/day)
6,100 mg/kg
104mg
15 mg
9,000 mg/kg
(serious)
9,000 mg/kg
(serious)
9,000 mg/kg
(serious)
3.2% (less
serious)
10 mg (less
serious)
0.2mg (less
serious)
2.5% (less
serious)
3 1 mg (less
serious)
16 mg (less
serious)
207 mg (less
serious)
3.2% (less
serious)
9,000 mg/kg
(serious)
Commensl990(68)
Fhgneretal. 1985(69)
Fhgneretal. 1985(69)
Fhgneretal. 1985(69)
Hannuksela et al. 1975
(70)
Kinnunen and
Hannuksela 1989 (71)
Kinnunen and
Hannuksela 1989 (71)
Trancik and Malbach
1982(72)
Warshaw and
Herrmann 1952 (73)
Willis etal. 1988(74)
Willis etal. 1989(75)
Trancik and Maibach
1982(72)
Hannuksela et al. 1975
(70)
Fhgneretal. 1985(69)
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.
9-44
-------
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents
Table 9-4
Acute Toxicity Data for Type I and II Formulated Fluids
Species
Fathead
Minnow
(Pimephales
promelas)
Rainbow Trout
(Oncorhynchus
mykiss)
Duration
and
Endpoint
96-hLC50
7-d NOEC
(mortality)
7-d NOEC
(growth)
7-d IC25
(growth)
48-h LC50
48-h LC50
96-hLC50
7-dLC50
96-hLC50
96-hLC50
48-h LC50
7-d LC50
96-hLC50
96-hLC50
96-hLC50
Fluid
Type
I
I
I
I
I
I
I
I
I
II
II
II
I
I
II
Life
Stage
14 d
7d
7d
7d
7d
60 d
60 d
60 d
7d
7d
7d
7d
0.3-
5.0 g
juvenile
juvenile
Temp.
(°C)
20-25
25
25
25
25
21
21
21
25
21-25
22-25
22
15
12
11-12
Concentration of
Ethylene Glycol
Formulated Fluid
(mg/L)
12,000 (76)
10,635 (35)
6,090 (37)
<3,330(37)
3,660 (37)
8,540 (37)
10,940 (77)
10,940 (77)
10,940 (77)
8,050 (37)
210 (76)
10,635 (35)
3,700 (76)
200 (76)
Concentration of
Propylene Glycol
Formulated Fluid
(mg/L)
4,900(76)
1,588(35)
270 (37)
98 (37)
110(37)
790 (37)
710(37)
100 (76)
18(77)
42 (77)
18(77)
2,096 (35)
3,200 (76)
38 (76)
Reference
Ward 1994 (76)
Beak Consultants 1995
(35)
Pillardl995(37)
Pillardl995(37)
Pillardl995(37)
Pillardl995(37)
Hartwell et al.
1993,1995(77)
Hartwell et al.
1993,1995(77)
Hartwell et al.
1993,1995(77)
Pillardl995(37)
Ward 1994 (76)
Hartwell et al. 1993,
1994(77)
Hartwell et al.
1993,1995(77)
Hartwell et al.
1993,1995(77)
Beak Consultants 1995
(35)
Ward 1994 (76)
Ward 1994 (76)
9-45
-------
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents
Table 9-4 (Continued)
Species
Ceriodaphnia
dubia
Water Flea
(Daphnia
magnet)
Sheepshead
Minnow
(Cyprinodon
variegatus)
Mysid
(Mysidopsis
bahia)
Marine algae
(Skeletonema
costatum)
Duration
and
Endpoint
7-d NOEC
(mortality)
7-d NOEC
(reprod.)
7-d IC25
48-hLC50
48-h EC50
96-h EC50
7-dEC50
(reprod.)
48-h LC50
48-h EC50
48-hEC50
96-h LC50
96-hLC50
96-h LC50
96-h LC50
96-hLC50
96-h LC50
Fluid
Type
I
I
I
I
I
I
I
I
I
II
I
II
I
II
I
II
Life
Stage
<24h
<24h
<24h
<24h
<24h
<24h
<24h
<24h
<24h
<24h
juvenile
juvenile
<24h
<24h
10,000
cells/m
L
10,000
cells/m
L
Temp.
(°C)
25
25
25
25
21
21
21
20
20-21
19-21
22
21-23
23-26
24-25
20-24
19-21
Concentration of
Ethylene Glycol
Formulated Fluid
(mg/L)
8,400 (37)
<3,330(37)
3,960 (37)
13,140(37)
7,730 (77)
5,384 (77)
1,817(77)
26,185(35)
7,100(76)
120 (76)
19,000(76)
270 (76)
1,100(76)
29 (76)
1,200(76)
7(76)
Concentration of
Propylene Glycol
Formulated Fluid
(mg/L)
660 (37)
600 (37)
640 (37)
1,020(37)
4,192(35)
6,000 (76)
280 (76)
7,000 (76)
290 (76)
1,800(76)
390 (76)
510(76)
29 (76)
Reference
Pillardl995(37)
Pillardl995(37)
Pillardl995(37)
Pillardl995(37)
Hartwell et al.
1993,1995(77)
Hartwell et al.
1993,1995(77)
Hartwell et al.
1993,1995(77)
Beak Consultants 1995
(35)
Ward 1994 (76)
Ward 1994 (76)
Ward 1994 (76)
Ward 1994 (76)
Ward 1994 (76)
Ward 1994 (76)
Ward 1994 (76)
Ward 1994 (76)
LC50 - Median lethal concentration that kills 50% of the test organisms.
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.
( ) - Reference for the data provided.
9-46
-------
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents
Table 9-5
Additional Aquatic Toxicity Data Sources for
Formulated Fluids
Glycol and Fluid Type
Ethylene Glycol Type I
Ethylene Glycol Type II
Propylene Glycol Type I
Propylene Glycol Type II
Species
Daphnia pulex
Water flea (Daphnia magna)
Chironamus tentans
Green algae (Selenastrum
capricornutum)
Chironamus tentans
Green algae (Selenastrum
capricornutum)
Green algae (Selenastrum
capicornutum)
Daphnia magna
Daphnia pulex
Green algae (Selenastrum
capicornutum)
Reference
Hartwell et al. 1993; 1995 (77)
HydroQual Laboratories 1994 (78)
Hartwell et al. 1993; 1995 (77)
Aeroports de Montreal & Analex
1995(49)
Ward 1994 (76)
Aeroports de Montreal & Analex
1995(49)
Aeroports de Montreal & Analex
1995(49)
Aeroports de Montreal & Analex
1994(50)
Ward 1994 (76)
Ward 1994 (76)
Hartwell et al. 1993; 1995 (77)
Hartwell et al. 1993; 1995 (77)
Ward 1994 (76)
( ) - Reference for the data provided.
9-47
-------
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents
Table 9-6
Aquatic Toxicity Results for Formulated Fluids and Their Components
Species
Ceriodaphnia
dubia
Fathead
minnow
(Pimephales
promelas)
Microtox®
Solution
PG + TTZ
TTZ only
PG only
Fully
formulated
fluid
PG +
additive
pack
PG + TTZ
TTZ only
PG only
Fully
formulated
flurd
PG +
additive
pack
PG + TTZ
TTZ only
PG only
Concentrations of
Solution Tested
PG/TTZ/Adpack
(mg/L)
10,000/600/0
10,000/120/0
20,000/110/0
0/150/0
0/180/0
31,000/0/0
5,000/3 l/Pa
9,400/52/Pb
10,000/0/PC
ll,000/0/Pd
10,000/120/0
20,000/110/0
0/150/0
0/190/0
99,000/0/0
5,000/28/Pa
9,000/52/Pb
10,000/0/PC
ll,000/0/Pd
10,000/58/0
10,000/600/0
0/48/0
10,000/0/0
Duration
48-h LC50
48-hLC50
48-h LC50
48-h LC50
48-h LC50
48-h LC50
48-h LC50
48-h LC50
48-h LC50
48-h LC50
96-h LC50
96-hLC50
96-h LC50
96-hLC50
96-h LC50
96-hLC50
96-h LC50
96-h LC50
96-hLC50
15-minEC50
15-minEC50
15-minEC50
15-minEC50
Concentration
measured as
PG
(mg/L)
1,647
8,770
11,842
NA
NA
15,052
3,829
3,224
5,122
4,919
3,566
6,742
NA
NA
34,060
1,716
1,525
1,434
1,866
1,127
153
NA
5,650
Concentration
measured as
TTZ
(mg/L)
98
109
68
108
102
NA
24
18
NA
NA
43
39
38
65
NA
10
8
NA
NA
6
9
7
NA
9-48
-------
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents
Table 9-6 (Continued)
Species
Microtox®
(cont.)
Solution
Fully
formulated
fluid
PG +
additive
pack
Concentrations of
Solution Tested
PG/TTZ/Adpack
(mg/L)
1 0,000/6 l/Pa
9,400/52/Pb
10,000/0/PC
Duration
15-minEC50
15-minEC50
15-minEC50
Concentration
measured as
PG
(mg/L)
950
1,497
5,247
Concentration
measured as
TTZ
(mg/L)
6
8
NA
Source: Reference (15).
PG - propylene glycol.
TTZ - 4-methyl-benzotriazole and 5-methyl-benzotriazole (common name: tolyltriazole).
NA - Not applicable.
LC50 - Lethal concentration that kills 50% of the test organisms.
EC50 - The median effective concentration. The concentration of a substance that causes a specified effect (generally
Pa - Present at an unknown concentration (proprietary information) from Manufacturer 1 (TTZ present).
Pb - Present at an unknown concentration (proprietary information) from Manufacturer 2 (TTZ present).
P° - Present at an unknown concentration (proprietary information) from Manufacturer 1 (without TTZ).
Pd - Present at an unknown concentration (proprietary information) from Manufacturer 2 (without TTZ).
9-49
-------
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents
Table 9-7
Aquatic Toxicity Data for Diethylene Glycol
Species
Rainbow trout
(Oncorhynchus
mykiss)
Fathead minnow
(Pimephales
promelas)
Guppy (Poecillia
reticulata)
Goldfish
(Carassius
auratus)
Clawed toad
(Xenopus laevis)
Water flea
(Daphnia magna)
Green algae
(Selenastrum
capricornutum)
Sheepshead
minnow
(Cyprinodon
variegatus)
Duration &
Endpoint
24-hLC50
48-h LC50
72-hLC50
96-hLC50
24-h LC50
48-h LC50
72-hLC50
96-h LC50
96-hLC50
168-hLC50
24-hLC50
48-h LC50
24-hLC50
48-h LC50
24-hEC50
48-h EC50
72-hEC50
96-h EC50
14-dEC50
24-hLC50
48-h LC50
72-hLC50
96-hLC50
Life Stage
4.1 cm & 0.64 g
4.1cm&0.64g
4.1 cm & 0.64 g
3. 5 - 4.1 cm & 0.42
- 0.64 g
3.1cm&0.3g
3.1 cm & 0.3 g
3.1cm&0.3g
3.1 cm & 0.3 g
19.1 mm & 0.102 g
2-3 cm
6.2cm& 3.3 g
3-4 weeks old
< 24 h old
< 24 h old
l,OOOcells/mL
l,OOOcells/mL
l,OOOcells/mL
l,OOOcells/mL
l,OOOcells/mL
0.74 g
0.74 g
0.74 g
0.74 g
Temp.
(°C)
12
12
12
12-15
22
22
22
22
24.9
22
20
20
20-22
20
24
24
24
24
24
20
20
20
20
Concentration of
Diethylene Glycol
(mg/L)
87,100(12)
79,800 (12)
55,400 (12)
52,800 (12)
62,934 (35)
86,800 (12)
86,800 (12)
86,800 (12)
84,100(12)
75,200 (79)
61,000(43)
>5,000 (39)
20,358 (35)
20,496 (35)
3,065 (44)
>10,000 (48)
78,500 (12)
47,200 (12)
6,400 (12)
24,000 (12)
6,400 (12)
19,900(12)
37,000 (12)
90,700 (12)
87,900 (12)
79,600 (12)
62,100(12)
Reference
Wardetal. 1992(12)
Wardetal. 1992(12)
Wardetal. 1992(12)
Wardetal. 1992(12)
Beak Consultants 1995 (35)
Wardetal. 1992(12)
Wardetal. 1992(12)
Wardetal. 1992(12)
Wardetal. 1992(12)
Geigeretal. 1990(79)
Konemannl981 (43)
Bridie et al. 1979(39)
Beak Consultants 1995 (35)
deZwart and Zloof 1987 (44)
Bringmann and Kuhn 1977 (48)
Wardetal. 1992(12)
Wardetal. 1992(12)
Wardetal. 1992(12)
Wardetal. 1992(12)
Wardetal. 1992(12)
Wardetal. 1992(12)
Wardetal. 1992(12)
Wardetal. 1992(12)
Wardetal. 1992(12)
Wardetal. 1992(12)
Wardetal. 1992(12)
9-50
-------
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents
Table 9-7 (Continued)
Species
Mysid (Mysidopsis
bahia)
Brine shrimp
(Artemia salina)
Marine algae
(Skeletonema
costatum)
Duration &
Endpoint
24-h LC50
48-h LC50
72-hLC50
96-h LC50
24-h LC50
24-h EC50
48-hEC50
72-h EC50
96-hEC50
14-dEC50
Life Stage
2.4 mg
2.4 mg
2.4 mg
2.4 mg
nauplii
l,OOOcells/mL
l,OOOcells/mL
l,OOOcells/mL
l,OOOcells/mL
l,OOOcells/mL
Temp.
(°C)
22
22
22
22
24.5
20
20
20
20
20
Concentration of
Diethylene Glycol
(mg/L)
54,900 (12)
43,800 (12)
42,900 (12)
36,900 (12)
>10,000 (52)
8,900 (12)
26,900 (12)
27,300 (12)
40,800 (12)
22,600 (12)
Reference
Wardetal. 1992(12)
Wardetal. 1992(12)
Wardetal. 1992(12)
Wardetal. 1992(12)
Price etal. 1974(52)
Wardetal. 1992(12)
Wardetal. 1992(12)
Wardetal. 1992(12)
Wardetal. 1992(12)
Wardetal. 1992(12)
LC50 - Median lethal concentration that kills 50% of the test organisms.
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.
( ) - Reference for the data provided.
9-51
-------
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents
Table 9-8
Mammalian Toxicity Data for Diethylene Glycol
Exposure Type
Inhalation
Oral
Dermal
Species
Mouse
Human
Dog
Guinea pig
Cat
Mouse
Rabbit
Rat
Rabbit
(intravenous)
Mouse
(subcutaneous)
Rabbit (skin)
Mouse
(intraperitoneal)
Rat (intravenous)
Rat (subcutaneous)
Rat
(intraperitoneal)
Typical Dose
Lowest published lethal
concentration
Lowest published lethal
dose
LD50
LD50
LD50
LD50
LD50
LD50
Lowest published lethal
dose
Lowest published lethal
dose
LD50
LD50
LD50
LD50
LD50
Amount
130
1,000
9,000
7,800
3,300
23,700
4,400
12,565
2,236
5,000
11,890
9,719
6,565
18,800
7,700
Units
mg/m3/2 hours
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
Source: Reference (23).
LD50 - Median lethal dose that kills 50% of the test organisms.
9-52
-------
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents
Table 9-9
Aquatic Toxicity Data for Isopropanol
Species
Fathead minnow
(Pimephales
promelas)
Water flea (Daphnia
magnet)
Goldfish (Carassius
auratus)
Brown shrimp
(Crangon crangon)
Guppy (Poecilia
reticulatd)
Green algae
(Scenedesmus
quadricauada)
Microtox™
(Photobacterium) test
Duration & Endpoint
l-hLC50
24-hLC50
48-h LC50
72-hLC50
96-h LC50
EC50 (reproduction)
NOEC (reproduction)
NOEC (growth)
24-hLC50
24-hLC50
48-h LC50
98-h LC50
7-dLC50
7-dEC0
5-min EC50
Life
Stage
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
Temperature
(°C)
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
Concentration of
Isopropanol (mg/L)
11,830
11,160
11,130
11,130
11,130
3,010
2,100
757
9,500
>500
1,400
1,150
7,060
1,800
22,800
Source: Reference (20).
LC50 - Median lethal concentration that kills 50% of the test organisms.
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.
9-53
-------
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents
Table 9-10
Mammalian Toxicity Data for Isopropanol
Exposure Type
Inhalation
Oral
Dermal
Species
Rat
Mouse
Human
Rat
Dog
Rabbit
Mouse
Rat
Dog
Cat
Rabbit
Mouse
Guinea
Pig
Hamster
Frog
Typical Concentration/Dose
Lowest published lethal concentration
Lowest published lethal concentration
Lowest published toxic dose
Lowest published lethal dose
LD50
LD50
LD50
LD50
LD50 (intraperitoneal)
LD50 (intravenous)
Lowest published lethal dose (intravenous)
Lowest published lethal dose (intravenous)
LD50 (skin)
LD50 (intravenous)
LD50 (intraperitoneal)
LD50 (intraperitoneal)
Lowest published lethal dose (subcutaneous)
LD50 (intravenous)
LD50 (intraperitoneal)
LD50 (intraperitoneal)
Lowest published lethal dose (par)
Amount
16,000
12,800
223 - 14,432
3,570 - 5,272
5,045
4,797
6,410
3,600
2,735
1,088
5,120
1,963
12,800
1,184
667
4,477
6,000
1,509
2,560
3,444
20,000
Units
mg/m3/4 hours
mg/m3/3 hours
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
Source: Reference (28).
LD50 - Median lethal dose that kills 50% of the test organisms.
9-54
-------
Section 10.0 - Environmental Impacts
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
10-1
-------
Section 10.0 - Environmental Impacts
discusses reports of environmental impacts from the discharge of deicing/anti-icing agent-
contaminated 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
10-2
-------
Section 10.0 - Environmental Impacts
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
Ethylene Glycol
Propylene Glycol
Half-Life
Aquatic
Aerobic Conditions
2 to 12 days
1 to 4 days
Anaerobic Conditions
4 to 48 days
3 to 5 days
Soil
0.2 to 0.9 days (5 -22 hours)
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
Literature values for BOD5 (at 20 °C), mg O2/L glycol
Literature values for BOD5 (at 20 °C), g O2/g glycol
Ethylene glycol manufacturer values for theoretical oxygen
demand (i.e., ultimate BOD), g O2/g glycol
Propylene glycol manufacturer values for average
COD:BOD ratio
Ethylene Glycol
400,000 - 800,000
0.4-0.7
1.3
2.08
Propylene Glycol
1,000,000
1
1.7
2.23
BOD5 - 5-day biochemical oxygen demand.
COD - Chemical oxygen demand.
Source: References: (3, 4, 7).
10-3
-------
Section 10.0 - Environmental Impacts
In comparison, the BOD5 of raw domestic sewage is approximately 200 mg of oxygen per liter of
sewage while the BOD5 of treated effluent (discharged to receiving streams) is about 20 mg of
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 4°C). 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 BOD5 at
20 °C 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 5 at 20 °C may be a more accurate indicator of what is occurring in the environment.
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
10-4
-------
Section 10.0 - Environmental Impacts
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 25 °C) for ethylene
glycol and propylene glycol are 2.3xlO"10 atm-m3/mol and 1.2-1.7xlO~8 atm-m3/mol, respectively
(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
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Section 10.0 - Environmental Impacts
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
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Section 10.0 - Environmental Impacts
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
Type I - EG based
(concentrate)
Type I - PG based
(concentrate)
Type II - PG based
Type IV - EG
based
Type IV - PG based
COD
(mg/L)
1,260,000
1,400,000
NA
945,000
794,000
BOD, Day 5
(mg/L)
873,000
840,000
730,000
463,000
520,000
BOD, Day 10
(mg/L)
1,070,000
NA
NA
576,000
NA
BOD, Day 15
(mg/L)
NA
NA
NA
775,000
NA
BOD, Day 20
(mg/L)
1,210,000
NA
NA
935,000
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
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Section 10.0 - Environmental Impacts
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.
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Section 10.0 - Environmental Impacts
Fluid Type
Type I - EG based
Type IV - EG based
IC50 (mg/L)
64,000 (or 6.4% concentration)
9,100 (or 0.91% concentration)
NOEC (mg/L)
NA
2,500 (or 0.25% concentration)
Source: Reference (13).
NOEC - No-observed-effect concentration.
IC50 - Concentration that inhibits growth in 50% of the test organisms.
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
Ethylene
Glycol
Propylene
Glycol
Product Name
Deicing Fluid Concentrate
Deicmg Fluid XL 54
Deicing Fluid "50/50"
Deicing/Anti-icing Fluid ULTRA+
Typical Deicing Fluid "45/55"
Fluid
Type
I
I
I
IV
I
Glycol
Content
(% wt.)
92
54
48.4
64
55
Glycol
Content
(Ib/gal)
8.52
4.84
4.3
5.79
4.78
Glycol Air
Emissions
(Ib glycol per 10,000
gal applied)
9.37
5.32
4.73
6.37
8.87
Source: Reference (2).
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Section 10.0 - Environmental Impacts
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.
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Section 10.0 - Environmental Impacts
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 BOD5 of
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).
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Section 10.0 - Environmental Impacts
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 BOD5 (at 20 °C) of isopropanol, with results ranging from 60 -
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 (k^) is very high (4.89E-06) for isopropanol (23). A high
k^x 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.
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Section 10.0 - Environmental Impacts
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
25 °C), 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 20°C and negligible degradation occurs at temperatures of less than 8°C (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 20 °C)
was reported as 94% (26).
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Section 10.0 - Environmental Impacts
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 BOD5 values are in the range of
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 BOD5 values for CMA.
Sodium Acetate
Sodium acetate is readily biodegradable even at low temperatures. One
manufacturer's sodium acetate-based deicer has a BOD5 of 0.58 grams of oxygen per gram of
anhydrous sodium acetate at 20 °C. 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
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Section 10.0 - Environmental Impacts
show that the newer chemicals are "relatively benign" compared to urea and glycols, and are
summarized as follows:
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.
CMA - had little or no impact on water chemistry, and calcium,
magnesium, and acetate were all readily detected.
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,
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Section 10.0 - Environmental Impacts
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 anti-
icing 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
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Section 10.0 - Environmental Impacts
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.
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Section 10.0 - Environmental Impacts
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
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Section 10.0 - Environmental Impacts
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
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Section 10.0 - Environmental Impacts
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.
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Section 10.0 - Environmental Impacts
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.
10-21
-------
Section 10.0 - Environmental Impacts
Date
4/12/93
4/13/93
4/14/93
4/15/93
4/20/93
Influent Ethylene
Glycol Concentration
(mg/L)
36
20
2.7
14
16
Effluent Ethylene
Glycol Concentration
(mg/L)
13
11
3.5
7.9
4.1
Percent Removal
64
45
NR
44
74
NR - Not removed.
Data based on a discharge of 1,500 Ibs/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.
10-22
-------
Section 10.0 - Environmental Impacts
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 (DCNT10481).
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).
10-23
-------
Section 10.0 - Environmental Impacts
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 Tl 1097).
16. Calculation Sheets for COD and BOD Concentrations for an Ethylene Glycol-
Based Type I Formulation (DCN Tl 1098).
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 TCTSAV 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 (SIPS). 1997.
25. Aldrich Catalog Handbook of Fine Chemicals. 1996-1997.
26. Material Safety Data Sheets and Product Specifications for Runway Deicers (DCN
T10586).
10-24
-------
Section 10.0 - Environmental Impacts
Table 10-1
Ultimate BOD Values for Pure Ethylene Glycol and
Propylene Glycol Acclimated Sludge Seeds
Day
Ethylene Glycol
BOD Value (in mg O2/L)
Propylene Glycol
BOD Value (in mg O2/L)
4° C -1.3 or 3.3 mg/L test substance
0
5
10
17
27
35
0
150,000
150,000
300,000
525,000
825,000
0
75,000
150,000
225,000
375,000
675,000
4°C - 6.7 or 10.0 mg/L test substance
0
5
10
17
27
35
0
30,000
45,000
90,000
165,000
495,000
0
0
60,000
120,000
510,000
900,000
4°C - 20.0 mg/L test substance
0
5
10
17
27
0
10,000
20,000
30,000
65,000
0
0
15,000
40,000
Discarded
10 °C - 1.3 or 3.3 mg/L test substance
0
5
10
16
20
27
35
0
-75,000
300,000
600,000
825,000
1,350,000
1,800,000
0
-75,000
675,000
1,050,000
1,200,000
1,575,000
2,100,000
10-25
-------
Section 10.0 - Environmental Impacts
Table 10-1 (Continued)
Day
Ethylene Glycol
BOD Value (in mg O2/L)
Propylene Glycol
BOD Value (in mg O2/L)
10 °C - 6.7 or 10.0 mg/L test substance
0
5
10
16
20
27
35
0
0
105,000
360,000
870,000
1,005,000
1,155,000
0
30,000
615,000
960,000
1,005,000
1,140,000
1,290,000
10 °C - 20.0 mg/L test substance
0
5
10
16
0
0
40,000
350,000
0
35,000
Discarded
Not Tested
Source: Reference (11).
10-26
-------
Section 10.0 - Environmental Impacts
Table 10-2
Biological Degradation Results for Diethylene Glycol
Parameter
Diethylene glycol
concentration (mg/L)
Biomass
Temp. °C
pH
Detention time (hours)
Initial COD
concentration (mg/L)
Effluent COD
concentration (mg/L)
Removal rate (I/day)
Percent removal
Run
1
2,100
acclimated
19.3
unbuffered
27
3,100
2,300
0.31
25.8
2
1,700
acclimated
9.8
unbuffered
60
5,600
3,900
0.17
30.4
3
1,000
acclimated
19.2
buffered
48
3,200
1,040
1.1
67.5
4
160
acclimated
19.4
unbuffered
33
250
30
5.3
88
Source: Reference (3).
10-27
-------
Section 10.0 - Environmental Impacts
Table 10-3
Reported Environmental Impacts from Airport Deicing Operations
Airport
Site/Study
Exposure
Environment
Biota/Effect
Impacts (a)
Seattle-Tacoma
International
Seattle, WA
(SEA)
Miller Creek, Des
Moines Creek, Puget
Sound
Ethylene glycol in receiving
streams due to runoff
Toxic effects on fish
to
oo
1993 - Tacoma News Tribune reports "death"
of Miller Creek due to runoff from airport.
Salmon no longer present in creek. Airport to
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
County
White Plains, NY
(HPN)
Kensico Reservoir
Propylene glycol in reservoir
Population exposure
Rye Lake, Blind
Brook; Blind Brook
WWTP
Deicers in receiving streams
due to runoff and in discharges
to WWTP
1999 - New York Times reports propylene
glycol found in Kensico Reservoir at levels high
enough to set off warning system. Reservoir
serves New York City and most of southern
Westchester.
1997 - Journal article summarizes program to
improve storm water management at airport
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.
(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 (Continued)
Section 10.0 - Environmental Impacts
Airport
Site/Study
Exposure
Environment
Biota/Effect
Impacts (a)
General
Environmental
Impact of Deicers in
Airport Stormwater
Runoff
Deicers in receiving streams
and groundwater due to runoff
Toxic effects on aquatic life •
fish kills
1990 - Michigan DNR conducted investigation
into aircraft and runway deicing. Concerns
with aquatic toxicity of ammonia, oxygen
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.
to
VO
Lambert-St. Louis
International
St. Louis, MO
(STL)
Coldwater Creek
Ethylene glycol in receiving
stream due to runoff
Population exposure
1995 - St. Louis Post Dispatch reports
thousands of gallons of ethylene glycol entering
Coldwater Creek. Residents along creek report
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
International
Airport
Cleveland, OH
(CLE)
Rocky River
Toxic chemicals in receiving
stream
1991 - Columbus Dispatch reports state is in
litigation with airport over flow of chemicals
into Rocky River. Chemicals detected more
than decade ago, but no fish kills attributed.
Detroit
Metropolitan
Romulus, MI
(DTW)
Detroit River
Ethylene glycol in receiving
stream
1990 - Detroit Free Press reports state officials
investigating allegations of airport runoff
polluting Detroit River. Ethylene glycol
flowing untreated from ponds into storm drains.
(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 (Continued)
Section 10.0 - Environmental Impacts
Airport
Site/Study
Exposure
Environment
Biota/Effect
Impacts (a)
Dayton Municipal
Airport
Dayton, OH
(DAY)
Mill Creek
Ethylene glycol in receiving
stream and groundwater
Fish kills; population exposure
1991 - Columbus Dispatch reports fish kill in
Mill Creek in 1987.
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.
o
I
o
Chicago O'Hare
International
Chicago, IL
(ORD)
NRDC Lawsuit
Ethylene glycol releases
1998 - Chicago Tribune reports NRDC
contends O'Hare has violated federal reporting
requirements (time, place, quantity)
approximately 180 times since Nov. 1996 in its
use of ethylene glycol. Airport reports average
use of 241,689 Ibs/day. NRDC estimates
84,591 Ibs/day being released to environment.
EPA investigating allegations.
Cincinnati/
Northern
Kentucky
International
Erlanger, KY
(CVG)
Elijah Creek
Deicing chemicals in receiving
stream
Effects on aquatic life
population exposure; aesthetic
effects
1992 - Associated Press reports state has cited
airport for discharge of deicing chemicals.
Major impact on Elijah Creek. Discharges
harmed aquatic life, caused unpleasant odors
and discoloration of creek.
(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 (Continued)
Section 10.0 - Environmental Impacts
Airport
Site/Study
Exposure
Environment
Biota/Effect
Impacts (a)
Airborne Express
(ABXAir, Inc.)
Wilmington, OH
(ILN)
Lytle Creek
Deicers in receiving stream
Effects on aquatic life - fish
kills; population exposure;
effects on wildlife
1998 - Associated Press reports disappearance
of aquatic life in Lytle Creek and subsequent
disappearance of birds. Foul odors reported.
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
International
Portland, OR
(PDX)
Columbia Slough
Glycols in receiving water due
to runoff; urea in land area
Effects on aquatic life (glycols);
severe oxygen shortages but no
fish kills. Urea increased grass
growth, which attracted wildlife
and posed a hazard to jets.
1999 - Oregonian reports a Portland Legislator
(Randy Leonard) is drafting legislation (the
Columbia Slough bill) that would order the
airport to stop discharging glycol into any body
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.
(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 (Continued)
Section 10.0 - Environmental Impacts
Airport
Site/Study
Exposure
Environment
Biota/Effect
Impacts (a)
Minneapolis-St.
Paul International
Woodland, MN
(MSP)
Minnesota River
Glycols in receiving stream due
to runoff
Effects on aquatic life - low
oxygen levels but no
documented fish kills
1993 - Star Tribune reports state issued new
permit for airport requiring reduced discharges
and extensive monitoring. Glycol is adding
stress to Minnesota River and ability to recover
from other pollutants, particularly agricultural
chemicals.
Greater Buffalo
International
Cheektowaga, NY
(BUF)
Ellicott Creek
Ethylene glycol and propylene
glycol in receiving stream
1994 - Buffalo News reports on concerns for
Ellicott Creek. Residents report seeing foaming
material in stream.
o
I
to
Pittsburgh
International,
Pittsburgh, PA
(PIT)
McClarens Run,
Enlow Run, and
Montour Run
Propylene glycol and urea in
receiving water
Fish kills; population exposure
1998 - Pittsburgh Post-Gazette reports
Pennsylvania DEP ordered airport to correct
long-standing water pollution problems caused
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.
(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 (Continued)
Section 10.0 - Environmental Impacts
Airport
Site/Study
Exposure
Environment
Biota/Effect
Impacts (a)
PIT (cont.)
Montour Run and
Tributaries
Deicing fluids in receiving
streams due to runoff
Effects on aquatic life
1998 - Journal article presents results of 1996
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
International
Airport
Anchorage, AK
(ANC)
Lake Hood
Ethylene glycol in receiving
stream due to runoff
Toxic effects on wildlife
1991 - Anchorage Daily News reports concerns
for wildlife that use Lake Hood. Also concerned
with oil/grease and aviation fuel.
Baltimore/
Washington
International
Baltimore, MD
(BWI)
Sawmill Creek,
Stony Run, Cabin
Branch, Kitten
Branch, Muddy
Bridge Branch
Ethylene glycol in receiving
streams due to runoff
Toxic effects on aquatic life;
population exposure; aesthetic
effects
1998 - Washington Post/Baltimore Sun report
lawsuit filed by NRDC against airport for
violating CWA over past 3 years. Residents
complain of odor and foaming. Concern for
Chesapeake Bay. Problems with $16 million
dollar deicing collection system. Concentration
of glycol in Sawmill Creek more than 6X level
to kill aquatic life.
(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 (Continued)
Section 10.0 - Environmental Impacts
Airport
Site/Study
Exposure
Environment
Biota/Effect
Impacts (a)
BWI (cont.)
Toxicity of
Stormwater
Deicing chemicals in receiving
streams due to runoff
Potential acute toxicity to
aquatic life
1995 - Journal article on study designed to
investigate the acute toxicity of storm water
from BWI. Samples from winter storm events
caused acute toxicity to both fathead minnow
and daphnid with LC50 values as low as 1.0-
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
International
Airport
Denver, CO
(DIA)
Third Creek, Barr
Lake
Propylene glycol in receiving
stream
Effects on aquatic life - all life
killed due to low oxygen levels;
population exposure; aesthetic
effects
1997/1998 - Denver Post/Rocky Mountain
News report spills of propylene glycol into
Third Creek. All aquatic life for 2 miles in
Third Creek killed due to depletion of oxygen.
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.
(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 (Continued)
Section 10.0 - Environmental Impacts
Airport
Site/Study
Exposure
Environment
Biota/Effect
Impacts (a)
General
Management of
Aircraft Deicing
Fluids
Deicing chemicals in receiving
streams due to runoff and in
discharges to WWTPs
Toxic effects on aquatic life;
POTW operations effects
1994 - Journal article states principal
environmental impact of deicing activities is
oxygen demand. CBOD5 of ethylene glycol
ranges from 400,000-800,000 mg/L and
propylene glycol > 1 x 106 mg/L (untreated
domestic wastewaters is 200-300 mg/L). One-
half 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
Deicing Constituents
Deicers in receiving streams
and groundwater due to storm
water discharges
Toxic effects on aquatic life;
aesthetic effects
1992 - Master thesis research identifies use and
management practices of deicing constituents
(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.
(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 (Continued)
Section 10.0 - Environmental Impacts
Airport
Site/Study
Exposure
Environment
Biota/Effect
Impacts (a)
Major
International
North America
Detection of Aircraft
Deicing/Anti-icing
Fluid Additives
(ADFs) in Water
Monitoring Well
Tolytriazoles present in
subsurface water samples from
airport deicing activities
Toxic effects on microorganisms
1998 - Journal article presents results of
research that describes first evidence that
constituents within ADFs, other than glycols,
are present in subsurface water samples from a
major North American airport at
environmentally significant concentrations.
Tolytriazoles concentrations approximately 25
times higher than reported EC 50 values in
Microtox assays. Previous glycol levels from
well were 24,410 mg/L.
General
Environmental
Impacts of
America's Airports
Deicing fluids in receiving
streams due to runoff
1995 - NRDC study of most important
environmental issues and best management
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
safely 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.
(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.
-------
Section 10.0 - Environmental Impacts
Table 10-3 (Continued)
Airport
Site/Study
Exposure
Environment
Biota/Effect
Impacts (a)
General
Petition to Require
SIC 45,
Transportation by
Air, To Report
Releases of Toxic
Chemicals
1997 - NRDC, Defenders of Wildlife, National
Audubon Society, and Humane Society petition
EPA to initiate rulemaking requiring airports,
airline terminals, and aircraft maintenance
facilities to report releases of toxic 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.
(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.
-------
Section 11.0 - Pollutant Loadings and Costs
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.
11-1
-------
Section 11.0 - Pollutant Loadings and Costs
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.
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Section 11.0 - Pollutant Loadings and Costs
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
11-3
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Section 11.0 - Pollutant Loadings and Costs
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 Mini-
Questionnaire 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 glycol-
based 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.
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Section 11.0 - Pollutant Loadings and Costs
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
11-5
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Section 11.0 - Pollutant Loadings and Costs
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.
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Section 11.0 - Pollutant Loadings and Costs
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:
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Section 11.0 - Pollutant Loadings and Costs
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).
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.
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.
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
11-8
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Section 11.0 - Pollutant Loadings and Costs
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.
11-9
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Section 11.0 - Pollutant Loadings and Costs
Case
Discharges prior to implementation
of EPA' s Storm Water Program
Current discharges
Discharges following full
implementation of storm water
permit regulations
Discharges following
implementation of an effluent
guideline
Estimated Volume of ADF
Discharged to U.S. Surface Waters
(million gallons/yr)
28
21
17
3.6
Estimated Volume of ADF
Discharged to POTWs
(million gallons/yr)
0
2.1
>2.1
>2.1
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 BOD5. Since the biochemical
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 gly col-based and ethyl ene glycol-based
Type I fluids. The following table summarizes the pollutant loadings to U.S. surface waters and
POTWs.
Case
Discharges prior to
implementation of EPA' s
Storm Water Program
Current discharges
Discharges following full
implementation of storm water
permit regulations
Discharges following
implementation of an effluent
guideline
Estimated Loadings Discharged to
U.S. Surface Waters
ADF Concentrate
(million Ibs/yr)
126
95
75
16
BOD5 Range
(million Ibs/yr)
98 - 102
74-77
58-61
12-13
Estimated Loadings Discharged to
POTWs
ADF Concentrate
(million Ibs/yr)
0
9.6
>9.6
>9.6
BOD5 Range
(million Ibs/yr)
0
7.4-7.8
>7.4
>7.4
11-10
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Section 11.0 - Pollutant Loadings and Costs
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 ADF-
capture efficiency.
Airport
Group
Al
A2
A4
B2
C2
C3
Dl
E2
Management
Category
1
2
2
2
2
1
2
2
3
1
1
1
Airport
Denver International (DIA)
Minneapolis-St. Paul International (MSP)
Chicago O'Hare International (ORD)
Dallas/Ft. Worth International (DFW)
Salt Lake City International (SLC)
Baltimore /Washington International (BWI)
Bradley International (BDL)
General Mitchell International (MKE)
Kansas City International
Albany International
Greater Buffalo International
Greater Rockford
Capital Cost
(Year Installed)
$36 million (1995)
$1.75 million (1993)
$98 million (1996)
$1.7 million (1997)
$27. 8 million (1998)
$22 million (1997)
$17.7 million (1999)
Not available
$8.5 million (1999)
$30.25 million (1989-
1998)
$5.6 million (1996)
$1.8 million (1994)
Annual
Operating Cost
$550,000
$1.4 million
$1 million
Not available
$760,000
Not available
Not available
$1 million
Not available
$325,000
$100,000
$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
11-11
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Section 11.0 - Pollutant Loadings and Costs
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).
11-12
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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
Dallas/Ft. Worth International
Arrport (DFW)
Minneapolis-St. Paul
International Airport (MSP)
Kansas City International Airport
(MCI)
Denver International Airport
(DIA)
Albany International Airport
(ALB)
Description of Management Project
Two 3-million-gallon detention ponds with liners and covers; pumping
station; diversion box; and grit chamber with oil skimmer
Three 1 -million-gallon storage ponds with liner, leak detection system, and
monitoring wells; an operations center with boiler and recirculation pump
for preventing wastewater freezing
Elgin vacuum trucks
Trench drains around passenger terminals; a diversion box; two 1 -million-
gallon concrete wastewater storage basins; modifications to the Todd Creek
Wastewater Treatment Plant
Wastewater collection system for nine aircraft deicing pads and United
Airlines gates; three 420,000-gallon wastewater storage tanks; two
detention ponds (total capacity 12 million gallons; ADSI glycol recycling
plant; glycol storage tanks
Elgin vacuum truck
Retrofitting 16 deicer trucks with dripless fittings and automatic filling
shut-off valves
Construction of a wastewater collection system at passenger terminals and
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
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
Year Construction
Completed or
Equipment Acquired
1997
1993
Unknown
Under construction
1995
Unknown
Unknown
1989
1989 to Present
Capital Costs
$1.7 million
$1 million
$275,000 each
$8.5 million
(estimated)
$36 million
$248,000
$4,000
$10 million
$20 million
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Section 11.0 - Pollutant Loadings and Costs
Table 11-1 (Continued)
Airport/Source
Greater Rockford Airport (RFD)
Bradley International Airport
(BDL)
Buffalo-Niagara International
Airport (BUF)
Chicago O'Hare International
Airport (ORD)
Description of Management Project
Wastewater treatment facility (includes a 16-million-gallon lined detention
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)
Two Tennant™ vacuum trucks
One truck-mounted Ramp Ranger™
One trailer-mounted Ramp Ranger™
One AR Plus Interceptor™
Construction of deicing pad including three aircraft deicing stations, a
deicing pad control tower, ADF storage area with five 20,000-gallon ADF
storage tanks, a Siamese drainage collection system with automated drain
valves, and two 1 -million-gallon underground storage tanks
Installation of storm drain valves and coating pavement surface with a
sealant (cargo and GA facilities only)
Construction of an underground storm water pipe for conveying
wastewater from the cargo area to a contaminated wastewater storage
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
Snow dump improvements including concrete pad, drainage collection
system, and piping to existing detention ponds
Construction of hold pad with drainage collection system and a lined
detention pond
Expansion of wastewater storage facility at North Detention Pond including
two additional detention ponds and junction control chambers; installation
of a drainage collection system for north airfield and aircraft maintenance
hangars
Four aboveground storage tanks for ADF with containment structures and
deicer truck filling stations
Year Construction
Completed or
Equipment Acquired
1994
1990
Unknown
Unknown
Unknown
Summer 1999
1995
November 1999
Planned
1996
Planned
1996
Capital Costs
$1.8 million
$140,000
$211,000
$180,000
$200,000
$17 million
(estimated)
$1.2 million
$4.2 million
(estimated)
$435,000
(estimated)
$10 million
$80 million
(estimated)
$3.3 million
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Section 11.0 - Pollutant Loadings and Costs
Table 11-1 (Continued)
Airport/Source
Salt Lake City International
Airport (SLC)
G. Frigon/Dames & Moore
EFX
ATA member
AR Plus/VQmp
Air Canada
ARPlus
Description of Management Project
Six primary aircraft deicing pads; five secondary deicing pads; three 3-
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)
Glycol recycling plant
Pinch valves
Butterfly valves
EFX anaerobic biological treatment system (not including storm water
collection and equalization) at Albany International Airport (ALB)
Ice detection system
Large blankets (for wings)
Storm drain inserts
High-capacity vacuum unit
Wetland for storm water management at Edmonton airport, Alberta,
Canada
6" valve Interceptor™
3300G Ramp Ranger™
Year Construction
Completed or
Equipment Acquired
1998
Unknown
1998
Unknown
Unknown
1998
Unknown
Unknown
Unknown
Unknown
Under construction
Unknown
Unknown
Capital Costs
$23 million
$362,000
$4.5 million
$8,000 -
$16,000/each
$l,200/each
$1.6 million
$60,000
$10,000/aircraft
$1,200 -$1,800
$240,000 -
$250,000
$1 million
$600 - $800
$250,000
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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
General Mitchell
International Airport
(MKE)
Minneapolis-St. Paul
International Airport
(MSP)
Denver International
Airport (DIA)
Buffalo-Niagara
International Airport
(BUF)
Albany International
Airport (ALB)
Description of Management Project
Annual operating costs for vacuum truck and drain valves
Detention pond cleaning and sludge removal (cost per pond)
Annual operating and maintenance costs for holding ponds, boiler, and associated
equipment. Also includes monitoring costs, including biannual sampling from
monitoring wells
Annual costs for storm water monitoring and analytical analysis
Annual POTW charges for wastewater treatment
Annual wastewater transportation costs (including trucks and labor),
installation/removal of sewer plugs, and maintenance of sewer plugs
Annual POTW surcharges for BOD, TKN, and hydraulic load
Per hour energy costs for operation of InfraTek®
Annual BOD surcharge from POTW
Annual costs of storm water monitoring at three sites including: (1) quarterly
monitoring for volatile organics (benzene, toluene, and xylene) and semivolatile
organics; and (2) daily monitoring for glycol from October to May
Year
1998-1999
Unknown
Unknown
Unknown
Unknown
Unknown
Unknown
Unknown
Unknown
Unknown
Operating Costs
$1 million
(estimated)
$2,600
$270,000
$650,000
$150,000 -$200,000
$350,000
$550,000
(estimated)
$100
$1,800- $2,400
$50,000
(estimate)
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Section 11.0 - Pollutant Loadings and Costs
Table 11-2 (Continued)
Airport/Source
Albany International
Airport (ALB) (cont.)
Greater Rockford Airport
(RFD)
Chicago O'Hare
International Airport
(ORD)
Description of Management Project
Annual electricity for aeration of lagoons
Albany County Sewer District glycol/BOD annual disposal charges
Village of Colonie annual conveyance fees
Annual operating costs (e.g. electricity, chemicals) for operation of the airport's
wastewater treatment facility
Annual labor costs for operation of the airport's wastewater treatment facility
Per hour cost of leasing and operating Aero Snow™ portable snow melters (per
unit)
Annual POTW disposal costs
Year
1996
1995
1994
1993
1992
1991
1997
1996
1995
1994
1993
1992
1991
1996
1995
1994
1993
1992
1991
1998
1998
1998-1999
Unknown
Operating Costs
$80,633
$76,187
$79,823
$100,959
$122,557
$61,561
$15,756
$289,545
$220,381
$299,341
$277,369
$132,815
$121,044
$180,620
$143,665
$166,946
$173,318
$109,791
$93,217
$108,000
$60,000 - $75,000
$6,000
$800,000- $1 million
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Section 11.0 - Pollutant Loadings and Costs
Table 11-2 (Continued)
Airport/Source
Salt Lake City
International Airport
(SLC)
Dallas/Ft. Worth
International Airport
(DFW)
FAA
ARPlus
Description of Management Project
Operating expenses for recycling plant
POTW surcharge for discharges that exceed BOD limit
POTW charges
Operating the InfraTek® system at Rochester International Airport
3300G Ramp Ranger™ hourly operation
2800 Interceptor™ rental
3300 Ramp Ranger™ rental
T4000 Ramp Ranger™ rental
Catch basin inserts
Year
1998-1999
Unknown
Unknown
Unknown
Unknown
Unknown
Unknown
Unknown
Unknown
Unknown
Unknown
Unknown
Unknown
Unknown
Unknown
Unknown
Operating Costs
$760,000
$0.08/lb BOD
$1.07/1, 000 gallons
$200 - $500/aircraft
$1 00 -$110/hr of operation
$3,500/mo (1 -year rental
agreement)
$l,850/mo (3 -year rental
agreement)
$l,200/mo (5-year rental
agreement)
$19,500/mo
(1 -year rental agreement)
$10,320/mo
(3 -year rental agreement)
$6,770/mo
(5 -year rental agreement)
$5,215/mo
(1 -year rental agreement)
$2,765/mo
(3 -year rental agreement)
$l,815/mo
(5 -year rental agreement)
$27.30/mo
(3 -year rental agreement)
$18.75/mo
(5 -year rental agreement)
oo
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Section 11.0 - Pollutant Loadings and Costs
Table 11-2 (Continued)
Airport/Source
AR Plus (cont.)
Air Canada
EFX
Description of Management Project
Wastewater treatment costs based on concentration of glycol in collected
wastewater
Personnel costs
Wastewater treatment costs for Vancouver Int'l at Seattle POTW
EFX anaerobic biological treatment system @ 200 GPM and influent of 2,000
mg/L of COD (includes amortized capital and annual operating costs)
Year
Unknown
Unknown
Unknown
Unknown
Unknown
Unknown
Unknown
Unknown
Unknown
1999
Unknown
Operating Costs
No charge (>20% glycol)
$0.07/gal(16-20%)
$0.09/gal(ll -15%)
$0.12/gal(6-10%)
$0.15/gal(3-5%)
$0.18/gal(<3%)
$45/hour (project supervisor)
$35/hour (equipment operator)
$30/hour (field technician)
$0.1 5/L of wastewater
<$3. 00/1 ,000 gallons (annualized)
-------
Section 12.0 - Trends in the Industry
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).
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Section 12.0 - Trends in the Industry
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 glycol-
based 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 l/32nd of an inch of ice accumulation along the leading edge of
the wing of a large jet or l/64th of an inch on a smaller aircraft can decrease lift on takeoff from
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Section 12.0 - Trends in the Industry
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
Use of Propylene Gly col-Based ADFs (data from 21
airports)
Use of Type II/IV ADFs (data from 18 airports)
Percentage of Airport ADF Applied
1990
<50%
Assumed <1%
1996 to Present (a)
Average
Percentage
78
6.1
Range of
Percentages
11 to 100
OtolS
(a) Most data are for the 1996-1997 through the 1998-1999 deicing seasons, although some data include earlier years.
12-3
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Section 12.0 - Trends in the Industry
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.
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Section 12.0 - Trends in the Industry
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 5° C and 20° 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/anti-
icing 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:
• The variety of replacement chemical additives is small.
• Some possible chemical additives interact and therefore cannot be
combined.
• 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.
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Section 12.0 - Trends in the Industry
• Carcinogenic chemical additives are unacceptable.
• 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.
• 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
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Section 12.0 - Trends in the Industry
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).
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Section 12.0 - Trends in the Industry
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:
• Direct discharge at a controlled rate;
• Indirect discharge at a controlled rate;
• On-site wastewater treatment followed by direct or indirect discharge; and
• On-site or off-site glycol recycling/recovery followed by indirect discharge
of residual wastewater.
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Section 12.0 - Trends in the Industry
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
12-9
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Section 12.0 - Trends in the Industry
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 gly col-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 Tl 1046).
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).
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Section 13.0 - Relationship to Other Regulations
is.o 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
13-1
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Section 13.0 - Relationship to Other Regulations
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
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Section 13.0 - Relationship to Other Regulations
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 area-
specific 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.
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Section 13.0 - Relationship to Other Regulations
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 (NOT) to be covered by a general permit to
authorize storm water discharges (the deadline for submitting a NOT for existing facilities was
October 1, 1992). The NOT contains basic information such as the name and address of the
facility, the Standard Industrial Classification codes that best represent the principal products
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 NOT in accordance with the terms of the permit.
or
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Section 13.0 - Relationship to Other Regulations
General permit conditions and requirements are summarized below:
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.
Annual monitoring of storm water discharges from aircraft or airport
deicing areas for oil and grease, 5-day biochemical oxygen demand
(BOD5), chemical oxygen demand (COD), total suspended solids (TSS),
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.
Facilities are subject to record-keeping requirements, but generally do not
have reporting requirements. (NOT 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.
Estimation of the size of the drainage area and runoff coefficient of the
drainage area.
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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Section 13.0 - Relationship to Other Regulations
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:
Identification of the participants in the group application by precipitation
zone (Appendix E to §122);
Description of the industrial activities of participants and why they are
significantly similar to be covered by a general permit;
List of significant stored materials exposed to precipitation and materials
management practices used to diminish contact; and
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/anti-
icing operations are described in 60 FR 50998 (September 25, 1995) and include the following:
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.
Airports that use more than 100,000 gallons of gly col-based deicing/anti-
icing 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 BOD5, COD, ammonia,
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.
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Record precipitation event data.
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/anti-
icing 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
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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:
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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.
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.
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.
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.
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, BOD5,
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.
Flow measurements or estimates, and the total amount of discharge for the
storm event(s) sampled.
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.
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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 BOD5, TSS, and pH for
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
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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 quarter-
century, 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 water-
quality 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
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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
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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:
BOD5;
COD;
TSS;
• Ethylene and/or propylene glycol;
• Copper, lead, and zinc;
• Ammonia as nitrogen; and
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
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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 glycol-
based 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
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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)
CEP A, 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-of-
pipe" 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
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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
Chilomonasparamecium. Data gathered from Bringmann et al. (1980) determined that the 48-
hour lowest concentration at which effects were observed (LOEC) for growth inhibition in
Chilomonasparamecium is 112 mg/L of ethylene glycol. Following standard practices, a safely
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.
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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
Anal ex 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
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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-glycol-
contaminated 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
Freshwater
Marine
Warm-water biota
Cold-water biota
All
Life stage
Early
Other
Early
Other
All
Minimum Dissolved Oxygen
Concentration (mg/L)
6
5
9.5
6.5
>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.
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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.
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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 glycol-
based 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 FAA-
approved 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
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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 FAA-
approved 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
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Section 13.0 - Relationship to Other Regulations
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
1431 A. 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
13-23
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Section 13.0 - Relationship to Other Regulations
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/Anti-
Icing 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:
Fluids Subcommittee;
Deicing Facilities Subcommittee;
Holdover Time Subcommittee;
Training Subcommittee;
Ice Detection Subcommittee;
Methods Subcommittee;
Future Deicing Technology Subcommittee; and
Aircraft Ground Deicing Equipment Subcommittee.
13-24
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Section 13.0 - Relationship to Other Regulations
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 143 IB 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
13-25
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Section 13.0 - Relationship to Other Regulations
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
13-26
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Section 13.0 - Relationship to Other Regulations
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
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
13-27
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Section 13.0 - Relationship to Other Regulations
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 TDCN T10568).
2. U.S. Department of Health and Human Services. Toxicological Profile for
Ethylene Glycol and Propylene Glycol. September 1997 (DCN Tl 1084).
3. Meeting Summary for Albany Aircraft Deicing Summit. March 1999 (DCN
T10542).
4. Portland International Airport, Portland, OR. NPDES Permit (DCN Tl 1049).
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 Anti-
Icing and Deicing Fluids. May 1999 (DCN T11079).
13-28
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Table 13-1
Airport Permit Data for ADF-Contaminated Wastewater
Airport
Cleveland
Hopkins
International
(CLE)
Tri-State
(Huntington,
HTS)
Des Moines
International
(DSM)
Duluth
International
(DLH)
Anchorage
International
(ANC)
Type of
Permit
POTW
NPDES
Storm Water
(General)
NPDES
Storm Water
(Individual)
POTW
NPDES
Storm Water
NPDES
Storm Water
(General)
Parameters
Monitored
COD
NH3-N
Flow
TSS
pH
pH, TSS, O&G,
TOC, BOD5,
TKN, COD,
Nitrate-Nitrite,
Total P
BOD5
NH3-N
EG
pH
DO
BETX
O&G
pH
Flow
COD
BOD5, COD,
TSS, N, TKN,
NH3-N, P, EG,
PG, DEG, O&G,
pH
BOD5 COD,
TSS, O&G, EG,
PG, urea,
potassium,
acetate, NH3-N,
pH, flow
Effluent Limitation (mg/L unless
otherwise noted)
1,500 and 1 2,500 Ibs/day
72 and 600 Ibs/day
700 gpm and 1 MGD
Monitor
Monitor
Monitor
Outfall A Outfall B
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
5.0-10.5
1 50,000 gpd
10,000 Ibs/day
NPDES permit does not require
monitoring; however, it is considered
a BMP.
Monitor
Frequency
Once/week
Once/week
Once/month
Once/week
Once/month
Once/year for all parameters
Twice/week
Twice/week
Twice/week
Twice/week
Twice/week
Once/month
Once/month
Once/week
Continuously
Daily or as necessary to
control discharge
Sampling schedule varies
yearly
Once/year (during spring
snow melt) for all parameters
13-29
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Table 13-1 (Cont.)
Section 13.0 - Relationship to Other Regulations
Airport
Seattle-Tacoma
International
(SEA)
Billings Logan
International
(BIL)
Newark
International
(EWR)
Logan
International
(BOS)
General Mitchell
International
(MKE)
Type of
Permit
NPDES
Storm Water
(Individual)
NPDES
Industrial
(Interim)
NPDES
Storm Water
(Individual)
NPDES
Industrial
(Expecting
storm water
permit
approval)
NPDES
Storm Water
(Interim)
NPDES
Storm Water
(General)
Parameters
Monitored
TPH, TSS,
Turbidity, Fecal
coliform, BOD5,
EG, PG, Cu, Pb,
Zn, LC50
Flow
pH
O&G
TSS
BOD5
Total glycols
TPH
Fecal coliform
VOAs
Semivoas
Cu
Pb
Zn
LC50
pH, O&G,
BOD5, COD,
TSS, total glycol
Flow
pH
TPH
COD
TSS
O&G
TSS
pH
DO, BOD5,
COD, TSS,
O&G, pH, TKN,
NH3-N,
Total P,
Total Glycol,
Cu, Pb, Zn, Flow
Effluent Limitation (mg/L unless
otherwise noted)
Monitor
4,800 gpm
6-9
8 (monthly avg.); 15 (daily max.)
21 (monthly avg.); 33 (daily max.)
Monitor
Monitor
Monitor
Monitor
Monitor
Monitor
Monitor
Monitor
Monitor
Monitor
Monitor
Monitor
6-9
15
100
100
15
10
5-7
Monitor
Frequency
Eight times/year for all
parameters
Once/day
Once/week
Once/week
Once/week
Once/month
Once/month
Once/month
Once/month
Once/year
Once/year
Once/year
Once/year
Once/year
Once/year (based on previous
results)
Monitoring waived until 2000
Once/month
Once/month
Once/month
Once/month
Once/month
Three times/month
Three times/month
Three times/month
Four times/year for all
parameters
13-30
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Table 13-1 (Cont.)
Section 13.0 - Relationship to Other Regulations
Airport
Buffalo Niagara
International
(BUF)
Bradley
International
(BDL)
Salt Lake City
International
(SLC)
Greater Rockford
(RFD)
Airborne Air Park
(ABX)
Type of
Permit
POTW
NPDES
Storm Water
POTW
Storm Water
Industrial
NPDES
Storm Water
NPDES
Storm Water
(Individual)
Parameters
Monitored
Flow
EG + PG
BOD5
O&G
pH
TSS
VGA
Semivolatile
organics
Flow
O&G
pH
TKN
NH3-N
BOD5
EG
Surfactants
Benzene
Toluene
Max. daily flow
Max. flow rate
Flow per batch
PG
TSS
BOD5
COD
pH
Flow
O&G
BOD5
COD
Nitrate-Nitrite
pH
EG
PG
BOD5,pH, TSS,
N
COD, TSS, pH,
NH3-N, DO,
TDS, O&G
Effluent Limitation (mg/L unless
otherwise noted)
27,000 gallons/day
10,000 Ibs/day
250
100
5- 12
250
Monitor
Monitor
Monitor
1 5 (daily max)
6-9
Monitor
2.4 (daily avg.); 16 (daily max.)
30 (daily avg.)
500 (daily max.)
Monitor
Monitor
Monitor
288,000 gpd
200 gpm
20,000 gal
125
125
200
600
5.5- 10
Apr.-Sept. Oct. -Mar.
Monitor Monitor
10 daily max. 10 daily max.
Monitor 25(a)/35(b)
Monitor Monitor
Monitor Monitor
Monitor Monitor
N/A 70
N/A 70
Monitor
Monitor
Frequency
Once/month for all
parameters
Once/month
Once/month
Once/month
Once/month
Once/month
Once/month
Once/month
Once/month
Four times/year
Four times/year
Weekly for all parameters
during discharge to POTW
Once/month
Once/month
Twice/yr. (Oct-Mr once/yr.)
Twice/yr. (Oct-Mr once/yr.)
Twice/yr. (Oct-Mr once/yr.)
Once/month
Once/month
Once/month
Unknown
Four times/month for all
paramters (in winter)
Once/month for all
parameters (in summer)
13-31
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Table 13-1 (Cont.)
Section 13.0 - Relationship to Other Regulations
Airport
Denver
International
(DIA)
Albany
International
Airport (ALB)
Type of
Permit
POTW
NPDES
Storm Water
General
POTW
NPDES
Storm Water
General
Parameters
Monitored
Flow
BOD
As
Cd
Cr
Cu
Pb
Hg,
Mo
Ni
Se
Ag
PERC
Zn
COD
O&G
pH
TSS
PG
EG
BOD
TPH
Total P
Nitrate-Nitrite
TKN
Flow
Chloride
DO
BOD5
TSS
COD
Total glycols
BOD5
Benzene
o-xylene
m+p-xylene
Toluene
Lead
PG
Effluent Limitation (mg/L unless
otherwise noted)
Monitor
9 tons/day (daily max.); 7 tons/day
(monthly avg)
0.33
3.4
3.6
6.1
2.2
0.13
0.71
5.6
0.66
2.9
1.5
15.6
Wet Weather
Monitor
Monitor
Monitor
Monitor
Monitor
Monitor
Monitor
Monitor
Monitor
Monitor
Monitor
Monitor
Monitor
Monitor if COD
>75
Dry Weather/
Summer
Monitor
Monitor
Monitor
N/A
Monitor
N/A
N/A
Monitor
N/A
N/A
N/A
N/A
N/A
N/A
240
25
Monitor
Monitor
500 Ibs/acre (land applied)
0.008
0.005
0.01
0.005
0.05
1
Frequency
Continuously
Once/hour
Unspecified but
representative of discharge
Wet Weather
Once/day
Once/mo.
Once/mo.
Once/mo.
Once/mo.
Four times/yr.
Four times/yr.
Four times/yr.
Four times/yr.
Four times/yr.
Four times/yr.
Four times/yr.
Four times/yr.
Once/week
Dry
Weather/
Summer
Monitoring
is required
whenever
the DIA
staff,
during the
inspection
of outfalls,
observes or
suspects an
illicit
discharge.
Once/day for all parameters
Once/month for all
parameters (except PG)
Once/day during deicing
season
13-32
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Table 13-1 (Cont.)
Section 13.0 - Relationship to Other Regulations
Airport
Minneapolis-St.
Paul International
(MSP)
Kansas City
International
(MCI)
Chicago O'Hare
International
(ORD)
Type of
Permit
NPDES
Storm Water
(Interim)
NPDES
Storm Water
(Interim)
NPDES
Storm Water
POTW
POTW
NPDES
Storm Water
Parameters
Monitored
CBOD5
pH
Flow, TSS, NH3-
N,
O&G, TKN,
Total P, DO
COD, EG, PG,
BETX
Total Phenols,
As, Cd, Cr, Cu,
Pb, Hg, Ni, Si,
Zn, Cn
pH
EG
Flow
TPH
BOD5
COD
TSS
O&G
Flow
BOD5
BOD5
TSS
Flow
Flow
pH
BOD5
NH3-N
April-Oct.
Nov. -March
O&G
TDS
Effluent Limitation (mg/L unless
otherwise noted)
900 tons/year
6-9
Monitor
Monitor
Monitor
Monitor
6-9
Monitor
Monitor
10 (monthly avg.); 15 (daily max.)
30 (monthly avg.); 45 (daily max.)
90 (monthly avg.); 120 (daily max.)
50 (monthly avg.); 100 (daily max.)
10 (monthly avg.); 15 (daily max.)
75gpm
400 Ibs/day
Monitor
Monitor
Monitor
Outfall A Outfall B
Monitor Monitor
Monitor Monitor
Monthly Daily Monthly Daily
Avg. Max. Avg. Max.
10 20 20 40
1.5 3.0 1.5 3.0
3.6 7.2 3.6 7.2
15 30
1,000 1,000
Frequency
Once/day
Once/day
Once/day for all parameters
Three times/week for all
parameters
Once/week for all parameters
Four times/year
Once/month
Once/year
Once/month
Once/month
Once/month
Once/month
Once/month
Once/month
Once/day
Once/day
Every 6 million gallons
discharged
Once/month
Once/month
Once/month
Once/month
Once/month
Once/month
Once/month
13-33
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Table 13-1 (Cont.)
Section 13.0 - Relationship to Other Regulations
Airport
Portland
International
Airport (PDX)
Baltimore/
Washington
International
(BWI)
Type of
Permit
NPDES
Storm Water
POTW
Parameters
Monitored
Flow
COD
BOD5
DO
Bioassay
Methanol
Ethanol
Propanol
pH
BOD5
TSS
Phosphorus
TPH
Flow
Cadmium
Chromium
Copper
Lead
Nickel
Zinc
Effluent Limitation (mg/L unless
otherwise noted)
Outfall A
Monitor
Monitor
Monitor
Monitor
Monitor
N/A
N/A
N/A
Outfall B
Monitor
Monitor
Monitor
Monitor
N/A
Monitor
Monitor
Monitor
6-10
7,000 Ibs/day
300 mg/L
12 mg/L
100 mg/L
Monitor
0.21 mg/L
6. 89 mg/L
6. 59 mg/L
6.81 mg/L
2. 82 mg/L
17.85 mg/L
Frequency
During and one day following
deicing events between Nov.
1 and Apr. 30
Outfall A
Once/hour
Once/3 hours
Once/6 hours
Once/6 hours
Twice/year
N/A
N/A
N/A
Outfall B
Once/hour
Once/3hrs
Once/6hrs
Once/day
N/A
Once/day
Once/day
Once/day
During each batch discharge
from 600,000 gallon storage
tank
Once/year
Key: (a) Monthly average.
(b) 7-day average.
As - Arsenic
BOD5 - 5-day Biochemical Oxygen Demand
BETX - benzene, ethylbenzene, toluene, and xylene
Cd - Cadmium
COD - Chemical oxygen demand
Cu - Copper
DEG - Diethylene glycol
DO - Dissolved oxygen
EG - Ethylene glycol
Hg - Mercury
LC50 - Lethal concentration where 50% of test
organisms die
Mo - Molybdenum
N/A - Not applicable
N - Nitrogen
NH3-N - Ammonia as nitrogen
Ni - Nickel
O&G - Oil and grease
P - Phosphorus
PERC - Tetrachoroethylene
PG - Propylene glycol
IDS - Total dissolved solids
TKN - Total kjedahl nitrogen
TPH - Total petroleum hydrocarbons
TSS - Total suspended solids
VOA - Volatile organics
Zn - Zinc
13-34
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Section 13.0 - Relationship to Other Regulations
Table 13-2
Summary of Available Permit Data
Parameters Frequently
Monitored
Chemical Oxygen Demand
(COD)
Ammonia
pH
Total Suspended Solids
(TSS)
Oil and Grease (O&G)
5-day Biochemical Oxygen
Demand (BOD5)
Ethylene Glycol
Propylene Glycol
Total Glycols
Copper
Lead
Zinc
Range of NPDES
Limitations
90-120 mg/L
1-55 mg/L
5-9
10- 100 mg/L
8-30 mg/L
10- 150 mg/L
7-9 tons/day
900 tons/year
70-500 mg/L
I mg/L
NA
NA
NA
NA
Range of POTW
Limitations
600- 1,500 mg/L
400-12,500 Ibs/day
72 mg/L
600 Ibs/day
5-12
25-300 mg/L
100 mg/L
200-250 mg/L
7,000 Ibs/day
NA
10- 125 mg/L
10,000 Ibs/day
6.1 -6.59 mg/L
0.05-6.81 mg/L
15.6 -17.85 mg/L
Range of Sampling Frequency
I/day - I/year
I/day - I/year
I/day - I/ year
I/day - I/year
3/week - I/year
I/hour - I/year
2/week - I/year
I/day - I/year
I/day - 4/year
4/year - I/year
1 /month - I/year
4/year - I/year
NA - Not available.
13-35
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Section 14.0 - Economic Profile
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
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(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
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Section 14.0 - Economic Profile
commerce per year. Commercial service airports cannot be privately owned.1 The number of
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 thirty-
first 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
1 Boardings at private airports or airports without scheduled commercial service are included in the ACAIS. For
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).
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Section 14.0 - Economic Profile
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.2 The 30 large hubs in CY 1997
(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.3 In 1997, 106 airports "qualified" as having significant cargo-only service; activity at
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
2 FAA defines passenger enplanements as the number of revenue passenger boardings on aircraft engaged in air
commerce at airports that receive scheduled passenger service.
3 Gross landed weight of cargo refers to the rated maximum gross landing weight of each cargo-only aircraft type (i.e.,
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.
4 This includes airports such as Rickenbacker Airport in Columbus, OH, which reported zero boardings in 1997, but
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.
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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
5 GA airports excluded from the NPIAS include more than: 1,000 publicly owned-public use landing strips, 1,200
privately owned-public use landing strips, and 12,000 privately owned- private use landing strips.
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Section 14.0 - Economic Profile
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).
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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):
• Category A: 425,000 < operations < 850,000 per year
• Category B: 210,000 < operations < 425,000 per year
Category C: 100,000 < operations < 210,000 per year
• Category D: 50,000 < operations < 100,000 per year
• Category E: 10,000 < operations < 50,000 per year.
EPA divided snowfall data into four subcategories (8):
• Category 1: 60 inches < snowfall < 120 inches per year
• Category 2:30 inches < snowfall < 60 inches per year
• Category 3:15 inches < snowfall < 30 inches per year
• Category 4: 1 inch < snowfall < 15 inches per year.
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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.
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Section 14.0 - Economic Profile
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.
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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.6 Therefore, airport financial
6 Except in specific legal agreements signed prior to the 1982 law prohibiting such practices. Therefore, a few airport
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
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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):
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.
Nonoperating revenues (e.g., grants-in-aid (AIP), interest on investments,
subsidies by government, leasing of properties not related to operations);
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;
Nonoperating expenses (e.g., interest on outstanding debt, contributions to
government); and
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
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).
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higher fees the following year. Both terminal and landing fees, or landing fees only, may be
adjusted by the airport7.
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):
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.
7 Wells (9) claims that airports such as Los Angeles and Honolulu have approached "negative" landing fees in recent
years due to overall operating surpluses.
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• Greater use of the compensatory approach instead of the residual-cost
approach with modification or elimination of majority-in-interest clauses.
• 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 self-
sustaining 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
! In addition, EPA could not ensure the consistency or accuracy of the data contained in the survey.
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Section 14.0 - Economic Profile
agreement, the number of airports currently using compensatory or hybrid residual-
cost/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.9 Finally, operating expenses exceed operating revenues for
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 mini-
questionnaires; 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.10 To minimize burden to the respondent, airports were
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
9 For the large, medium, and small hubs as a group that responded to the AAAE survey, parking fees comprised almost
41% of parking and concession revenues, exceeding airline landing fees as a source of revenue.
10 The FAA utilized AAAE data from 1992 to characterize capital expenditures in its most recent NPIAS (6). As noted
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).
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Section 14.0 - Economic Profile
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.11 For large and medium hubs terminal expenditures are higher
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.12 These financial statements are the best source of publicly available
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
11 Airport #1 is a new airport, which may account for some of the apparent anomalies in its responses. For example,
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.
12 These financial statements are available at http://www.faa.gov/arp/arphome; choose "Browse by Topic" from the
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).
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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
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Section 14.0 - Economic Profile
$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,"
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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:
• 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).
• 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).
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• 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).
• 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).
• 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.
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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:
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
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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).
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.13 Airports must
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).
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).
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).
13 The FAA has proposed raising the maximum PFC charge. While endorsed by airports, this measure is opposed by
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).
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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:
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-in-
interest 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:
• 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).
• 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).
• 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
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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.
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.
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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.
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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
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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):
• 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.
• 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
• 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):
14 Part 121 operating certificates are required for aircraft carrying more than nine passengers, more than 7,500 pounds
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.
15 For EPA's purposes, small certificated and commuter airlines are essentially identical. They offer the same type of
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).
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• Major airlines: annual revenues greater than $1 billion;
• National airlines: annual revenues greater than $100 million, but less than
$1 billion;
• Large regional airlines: annual revenues greater than $20 million, but less
than $100 million; and
• 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-
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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.
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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).
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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.16 Moreover, in only one year did the airlines rate of return
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.
16 Figures for 1992 include a one-time-only accounting loss due to changes in accounting procedures that affected all
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).
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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.17 Economists typically measure industry
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 Herfmdahl 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
17 Some financial problems can be attributed to airlines learning to operate in an entirely new, highly competitive market
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)).
18 This view is not shared by all economists; see Shepherd & Brock (37), for example, for a less optimistic view of the
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.
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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.19 The existence of a second airline, or more, in a market provides the
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.20 Airlines are concerned with any cost component exhibiting
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).
19 Crandall argues that in addition to low barriers to entry for existing airlines to enter a market, there are few barriers to
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).
20 Robert Crandall, the legendary CEO of American Airlines, has been quoted as saying that one of his proudest
achievements at AA was saving the company $50,000 per year by reducing the number of cherry tomatoes in the in-
flight salads from three to two.
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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 Book21
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 Book22
21 Although the Airline Quarterly Financial Review does contain financial ratios for major carriers not contained in the
Yellow Book, the Yellow Book contains data that can be used to calculate important financial ratios.
22 BTS did indicate that this small certificated/commuter airline income data may be available to other government
agencies under certain circumstances (28).
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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.23 By using the same
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
23 ATA used heating degree days (an engineering index of heating fuel requirements), the number of days with
temperatures below 32° F, and inches of snow.
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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.24 Two points are apparent from this table: (1) the wide range of
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
24 In addition to key operational characteristics, ATA described important features of each airport's glycol collection
system.
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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.26 With that qualification, EPA considers the regional airline estimates similar to those
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
25 Cargo aircraft spend significantly longer periods of time on the ground, typically only "cycling once" per day
(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).
26 Regional airline respondents to the EPA minisurvey estimated a range of 35 to 50 deicing episodes in the 1997-98
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."
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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 glycol-
based 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
32° 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%
27 ATA argued that estimates based on snowfall underestimate the true national costs of deicing because zero snowfall
implies zero deicing costs, yet airlines do incur deicing costs even with zero or minimal snow, as can be seen in Table
14-17.
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respectively (44).28 Boeing projects somewhat slower growth for North American air
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).29 To the extent that increased passenger demand is accommodated through more
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
28 Air transportation growth projections are largely dependent on GDP growth projections; the FAA based its projections
on an average of DRI/McGraw-Hill's and The WEFA Group's forecasts.
29 Although Boeing sees little growth in average aircraft capacity, the FAA expects average aircraft capacity to grow by
approximately two seats per year, from 142.6 seats to 166.6 seats in 2009.
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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).
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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-to-
head 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 F AA-
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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).
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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 high-
profile, potentially volatile issues. It is possible that government agencies could respond to these
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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,
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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)).30 There is a wide range of publicly
30 Clarification by ATA of airline pricing policy is necessary to fill out the details of this analysis. At an EPA meeting
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
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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 route-
specific 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
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.
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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
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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 origin-
destination 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.
31 An opinion article by Robert Bork in the Wall Street Journal, and the subsequent rejoinders by Gerald Smith and
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).
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Section 14.0 - Economic Profile
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.32 Airports can also increase revenues through charges on concessions, parking, and other
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.
32 As of calender year 1996, 54 of 71 large and medium hubs had already imposed PFCs (ACAIS, 1997); however, there
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.
33 Compliance costs incurred by airports and not passed through to airlines in the form of higher landing fees may still
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
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Section 14.0 - Economic Profile
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.34 There should be no incentive for airlines to change their deicing decisions under such a
34 Note that at least one airport in Canada has implemented a deicing surcharge on all flights.
14-49
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Section 14.0 - Economic Profile
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
Telephone conversation between Sharon Glasgow, F AA Office of Airports,
Airport Capacity Branch, and Calvin Franz, ERG. September 15, 1998.
Federal Aviation Administration. National Plan of Integrated Airport Systems
1993-1997. Washington, DC. April 1995.
3. Federal Aviation Administration. National Plan of Integrated Airport Systems
fNPIAS;) 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/4 1 Ohome .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
rNPIAS;) 1998-2002. Washington, DC. 1999.
http ://www. faa. gov/arp/4 1 Ohome .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.
14-50
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Section 14.0 - Economic Profile
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/partl/chapterl/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-98-71Y 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.
14-51
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Section 14.0 - Economic Profile
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/fmalcom/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.
14-52
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Section 14.0 - Economic Profile
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 Long-
Range 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.
14-53
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Section 14.0 - Economic Profile
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.
14-54
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Section 14.0 - Economic Profile
Table 14-1
Passenger and Cargo Activity by FAA Airport Definition, 1997
Airport Type
Primary, Large Hub
% of total
Primary, Medium Hub
% of total
Primary, Small Hub
% of total
Primary, Nonhub
% of total
Nonprimary Commercial
Service (c)
% of total
Noncommercial Service
% of total
Total
FAA Airport
Definitions Based on
Percentage of National
Boardings (Brd)
l%<=Brd
0.25% <= Brd <1%
0.05% <= Brd < 0.25%
10,000 < Brd < 0.05%
2,500 <=Brd<= 10,000
NA
Number of
Airports
by Type
30
40
71
276
112
1,186
1,715
Passenger Activity
Total
Boardings
by Type
439,556,180
68.6%
132,472,093
20.7%
46,968,440
7.3%
21,191,850
3.3%
550,755
0.1%
824,388
0.1%
641,563,706
Average
Boardings
by Type
14,651,873
3,311,802
661,527
76,782
4,917
695
Maximum
Boardings
by Type
33,249,963
6,318,523
1,553,700
317,199
9,724
81,416
Minimum
Boardings
by Type
6,467,195
1,634,578
324,521
10,019
2,509
0
Cargo-Only Activity (a)
Number of
Airports (b)
28
29
34
9
2
4
106
Total Gross
Landed Weight of
Cargo
53,580,799,092
53,966,253,749
19,371,974,805
3,119,938,255
1,593,027,497
1,588,610,350
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).
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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
Year
Total Boardings (a)
Total Enplanements
# of Airports
1993
528,920,496
527,984,216
566
1994
573,575,959
572,608,645
575
1995
586,326,851
585,347,291
566
1996
621,613,161
620,410,923
540
1997
641,563,706
640,739,318
529
Total Enplanements by Airport Type
Large Hub Primary
# of Airports
Medium Hub
Primary
# of Airports
Small Hub Primary
# of Airports
Nonhub Primary
# of Airports
Nonprimary
# of Airports
341,729,124
27
118,290,399
38
49,045,057
83
18,193,093
269
726,543
149
380,292,229
29
126,220,983
40
44,941,969
71
20,396,930
281
756,534
154
393,110,251
29
129,792,590
42
41,489,614
67
20,197,540
273
757,296
155
418,425,819
29
137,813,925
42
43,807,189
70
19,748,437
272
615,553
127
439,556,180
30
132,472,093
40
46,968,440
71
21,191,850
276
550,755
112
Average Enplanements by Airport Type
Large Hub Primary
Medium Hub
Primary
Small Hub Primary
Nonhub Primary
Nonprimary
12,656,634
3,112,905
590,904
67,632
4,876
13,113,525
3.155,525
632,985
72,587
4,913
13,555,526
3,090,300
619,248
73,984
4,886
14,428,477
3,281,284
625,817
72,605
4,847
14,651,873
3,311,802
661,527
76,782
4,917
Enplanement Growth Rates
1993
NA
NA
1994
8.4%
8.5%
1995
2.2%
2.2%
1996
6.0%
6.0%
1997
3.2%
3.3%
Average
5.3%
5.3%
Growth Rates, Total Enplanements
NA
NA
NA
NA
NA
11.3%
6.7%
-8.4%
12.1%
4.1%
3.4%
2.8%
-7.7%
-1.0%
0.1%
6.4%
6.2%
5.6%
-2.2%
-18.7%
5.0%
-3.9%
7.2%
7.3%
-10.5%
7.2%
3.0%
-1.1%
4.1%
-6.0%
Growth rates, Average Enplanements
NA
NA
NA
NA
NA
3.6%
1.4%
7.1%
7.3%
0.7%
3.4%
-2.1%
-2.2%
1.9%
-0.5%
6.4%
6.2%
1.1%
-1.9%
-0.8%
1.5%
0.9%
5.7%
5.8%
1.5%
3.9%
1.6%
3.0%
3.4%
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).
-------
Section 14.0 - Economic Profile
Table 14-3
Airport Flight Operations by FAA Airport Definition, 1997
Airport Type
Primary, Large Hub
% of total
Primary, Medium Hub
% of total
Primary, Small Hub
% of total
Primary, Nonhub
% of total
Nonprimary, Commercial
Service
% of total
Noncommercial Service
% of total
Total
Number of
Airports by
FAA
Definition
30
40
71
276
112
NA
Number of
Airports
Reporting
Operations
30
40
70
157
11
110
418
Non-GA Operations Activity by Airport Definition
Total
Operations
12,920,538
48.0%
5,592,685
20.8%
3,967,527
14.7%
3,423,075
12.7%
171,669
0.6%
830,379
3.1%
26,905,873
Average
Operations
430,685
139,817
56,679
21,803
15,606
7,549
Maximum
Operations
847,901
311,088
170,446
107,481
59,783
105,774
Minimum
Operations
209,827
33,863
5,248
3,160
3,289
23
Average Operations by Aircraft Type and
Airport Definition
Carrier
306,706
86,740
18,501
2,139
2,055
185
Air Taxi
119,661
45,926
27,871
13,925
7,822
3,690
Military
4,317
7,152
10,307
5,739
5,729
3,674
GA
44,424
82,126
76,084
54,319
104,108
125,831
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).
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Section 14.0 - Economic Profile
Table 14-4
Airports of Concern, by Operations, Snowfall, and FAA Size Definitions (a)
Snowfall
Categorization
60" <= snow < 120"
30" <= snow < 60"
15" <= snow < 30"
l"<=snow<15"
Subtotal by Ops
FAA Definition
Large Hub
Medium Hub
Small Hub
Nonhub
Nonprimary
Noncomm. Svc.
Subtotal
Large Hub
Medium Hub
Small Hub
Nonhub
Nonprimary
Noncomm. Svc.
Subtotal
Large Hub
Medium Hub
Small Hub
Nonhub
Nonprimary
Noncomm. Svc.
Subtotal
Large Hub
Medium Hub
Small Hub
Nonhub
Nonprimary
Noncomm. Svc.
Subtotal
Large Hub
Medium Hub
Small Hub
Nonhub
Nonprimary
Noncomm. Svc.
Subtotal
Operations Categorization (b)
Ops "A"
1
0
0
0
0
0
1
5
0
0
0
0
0
5
2
0
0
0
0
0
2
2
0
0
0
0
0
2
10
0
0
0
0
0
10
Ops "B"
0
1
0
0
0
0
1
1
1
0
0
0
0
2
7
0
0
0
0
0
7
3
2
0
0
0
0
5
11
4
0
0
0
0
15
Ops "C"
0
0
2
0
0
0
2
0
3
0
0
0
0
3
0
5
0
1
0
1
7
0
5
0
0
0
0
5
0
13
2
1
0
1
17
Ops "D"
0
0
8
0
0
0
8
0
2
4
1
0
0
7
0
1
3
1
0
0
5
0
3
7
3
1
0
14
0
6
22
5
1
0
34
Ops "E"
0
0
3
14
0
3
20
0
0
8
31
1
5
45
0
0
7
22
1
4
34
0
0
7
25
2
2
36
0
0
25
92
4
14
135
Subtotal by
Snowfall
1
1
13
14
0
3
32
6
6
12
32
1
5
62
9
6
10
24
1
5
55
5
10
14
28
3
2
62
21
23
49
98
5
15
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).
14-58
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Section 14.0 - Economic Profile
Table 14-5
Airports with Potentially Significant Deicing Operations, by Operations and Enplanements (a)
Operations (Ops)
Categorization
425,000 <= Ops < 850,000
210,000 <= Ops < 425,000
100,000 <= Ops < 210,000
50,000 <= Ops < 100,000
1 0,000 <= Ops < 50,000
Total Airports of Concern
Number of
Airports
10
15
17
34
135
211
Average Operations within Airport Ops Class
Non-GA
Operations
567,680
320,679
144,138
74,236
24,685
Carrier
Operations
417,349
204,549
71,601
28,037
4,749
Air Taxi
Operations
147,917
111,314
59,534
33,253
14,037
GA
Operations
43,510
49,822
54,223
76,477
65,254
Average Enplanements within Airport Class
All
19,296,737
8,991,676
2,574,169
962,463
168,282
Large
Carrier
18,303,408
7,896,227
2,431,328
854,836
131,397
Commuter
438,088
564,009
124,987
92,478
36,679
Air Taxi
98
2,812
11,571
5,330
189
(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).
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Section 14.0 - Economic Profile
Table 14-6
Airport Operating Agreements by Airport Type
AAAE Survey Respondents, 1997 -1998
Airport Type
Large Hub
Medium Hub
Small Hub
Nonhub
General Aviation
Total
Number of
Respondents by Type
18
28
53
96
195
Type of Agreement
Residual
4
14
17
11
46
Compensatory
5
5
16
48
74
Hybrid
6
8
16
20
50
Other
3
2
4
17
26
Source: Reference (12).
14-60
-------
Section 14.0 - Economic Profile
Table 14-7
Airport Revenues by Airport Type for AAAE Survey Respondents, 1997 - 1998
Airport Type
Large Hub
% of total revenues
Medium Hub
% of total revenues
Small Hub
% of total revenues
Nonhub
% of total revenues
General Aviation
% of total revenues
Total
Number of
Respondent
s by Type
15
27
49
91
92
274
Average Airline
and Air Cargo
Revenues
$100,295,007
50%
$14,969,744
39%
$3,295,032
41%
$418,198
27%
$37,554
4%
$119,015,535
Average
FBO/GA
Revenues
$5,160,219
3%
$1,840,125
5%
$842,245
10%
$358,565
23%
$506,232
58%
$8,707,385
Average
Total Other
Revenues
$94,381,574
47%
$19,497,502
51%
$4,304,924
53%
$735,206
47%
$264,471
31%
$119,183,677
Average Total
Operating
Revenues
$200,090,311
$38,039,780
$8,117,894
$1,551,172
$865,988
$248,665,145
Average Total
Operating
Expenses
$106,506,742
$22,145,663
$5,916,717
$1,463,673
$938,491
$136,971,286
Average Total
Government
Subsidy
$0
$177,642
$338,164
$221,324
$218,829
$955,959
Average Total
Operating
Income
$93,583,569
$16,071,759
$2,539,341
$308,823
$146,327
$112,649,818
Source: Reference (12).
-------
Section 14.0 - Economic Profile
Table 14-8
Airport Expenditures for EPA Airport Mini-Questionnaire Recipients, 1997
Enplanements
Non-GA Operations
Airfield Areas
Terminal Areas
Hangars, cargo
facilities, and other
areas
General and
Administrative
Other Agencies (b)
Debt Service
Depreciation
Total
Large Hubs
Airport #1
16,600,000
476,000
4.0%
16.0%
1.0%
9.0%
3.0%
46.0%
21.0%
100.0%
Airport # 2
15,400,000
445,000
30.0%
30.0%
(a)
20.0%
0.0%
20.0%
(a)
100.0%
Airport # 3
12,100,000
381,000
13.0%
32.0%
1.0%
6.0%
0.0%
29.0%
18.0%
99.0%
Medium Hubs
Airport # 4
5,710,000
278,000
10.0%
20.0%
5.0%
24.0%
6.0%
35.0%
NA
100.0%
Airport # 5
2,640,000
214,000
22.6%
24.8%
3.2%
8.4%
1.7%
11.6%
27.7%
100.0%
Small Hubs
Airport # 6
818,000
67,000
21.1%
17.0%
7.1%
12.6%
10.5%
13.0%
18.7%
100.0%
Primary Commercial Service Nonhubs
Airport # 7
303,000
41,800
32.0%
20.0%
7.0%
16.0%
2.0%
23.0%
0.0%
100.0%
Airport # 8
120,000
21,500
16.0%
9.0%
6.0%
20.0%
0.0%
0.0%
49.0%
100.0%
Airport # 9
64,500
13,400
3.2%
5.9%
1.2%
8.3%
8.7%
2.0%
6.6%
35.9%
Airport #10
26,700
44,400
20.0%
13.0%
9.0%
20.0%
0.0%
0.0%
38.0%
100.0%
J^.
I
to
(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
Table 14-9
Airport Ownership by Airport Type
AAAE Survey Respondents, 1997 -1998
Airport Type
Large Hub
Medium Hub
Small Hub
Nonhub
General Aviation
Total
Number of
Respondents by
Type
18
31
53
108
130
340
Type of Ownership
Municipal
10
17
34
56
92
209
Multi-
government
4
2
1
8
4
19
Independent
Authority
2
8
17
37
23
87
Other
2
3
1
7
11
24
Source: Reference (12)
14-63
-------
Section 14.0 - Economic Profile
Table 14-10
Airport Capital Expenditures for EPA Airport Minisurvey Recipients, 1997
Enplanements
Non-GA Operations
Capital Expenditures
Airport Improvement
Grants
Passenger Facility
Charges
Other Government
Grants
Bonds
Rates and Charges
Other Revenue
Total
Majority-in-Interest
Clause
Large Hubs
Airport #1
16,600,000
476,000
$55,423
25.7%
33.7%
0.0%
33.1%
7.5%
0.0%
100.0%
No
Airport #2
15,400,000
445,000
$537,000
9.0%
40.0%
0.0%
51.0%
(c)
(c)
100.0%
No
Airport #3
12,100,000
381,000
$109,153
19.5%
18.8%
0.0%
40.9%
12.9%
8.0%
100.1%
Yes
Medium Hubs
Airport #4
5,710,000
278,000
$69,600,000
4.0%
13.0%
0.0%
80.0%
3.0%
0.0%
100.0%
Yes
Airport #5
2,640,000
214,000
$28,125
14.4%
0.0%
7.7%
60.1%
17.7%
0.0%
99.9%
Yes
Small Hubs
Airport #6
818,000
67,000
$12,000
28.0%
15.0%
0.0%
23.0%
28.0%
6.0%
100.0%
No
Primary Commercial Service Nonhubs
Airport #7
303,000
41,800
$2,756
67.0%
18.0%
0.0%
0.0%
15.0%
0.0%
100.0%
No(b)
Airport #8
120,000
21,500
$1,418
75.0%
10.0%
10.0%
0.0%
5.0%
0.0%
100.0%
No
Airport #9
64,500
13,400
$1,452,196
89.3%
8.3%
2.4%
0.0%
0.0%
0.0%
100.0%
No
Airport #10
26,700
44,400
$341
90.0%
5.0%
0.0%
0.0%
5.0%
0.0%
100.0%
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
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
4-Engine Turbojet
% of Total
3-Engine Turbojet
% of Total
2-Engine Turbojet (a)
% of Total
2-Engine Turboprop
% of Total
7,478
440
5.9%
1,212
16.2%
3,270
43.7%
1,639
21.9%
14,784,409
934,572
6.3%
2,378,145
16.1%
8,715,239
58.9%
2,602,374
17.6%
1,977
2,124
1,962
2,665
1,588
General Aviation (b)
Total (Fixed-wing)
2-Engine Turbojet
% of Total
2-Engine Turboprop
% of Total
1-Engine Piston
% of Total
160,577
3,971
2.5%
4,551
2.8%
150,980
94.0%
22,719,550
1,355,034
6.0%
1,243,572
5.5%
17,156,396
75.5%
141
341
273
114
(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).
14-65
-------
Section 14.0 - Economic Profile
Table 14-12
Air-Carrier Traffic Statistics by Carrier Type, June 1997 - June 1998
Carrier
Major
% of Total
National
% of Total
Large Regional
% of Total
Medium Regional
(a)
% of Total
Total
Number
13
9.0%
28
19.4%
15
10.4%
88
61.1%
144
100%
Passenger
Enplanements
(x 1,000)
534,040
83.4%
62,605
9.8%
7,768
1.2%
36,288
5.7%
640,701
100%
Cargo
Ton-miles
(x 1,000)
18,491,148
87.7%
2,390,465
11.3%
199,559
0.9%
13,937
0.1%
21,095,109
100%
Revenue
Passenger-miles
(x 1,000)
573,632,137
92.2%
35,052,261
5.6%
4,066,632
0.7%
9,238,469
1.5%
621,989,499
100%
Available
Seat-miles
(x 1,000)
807,270,192
91.2%
53,843,361
6.1%
6,490,996
0.7%
17,886,124
2.0%
885,490,673
100%
Load Factor
(%)
71.1%
65.1%
62.7%
51.7%
70.2%
Passengers
per
Aircraft-mile
112.6
63.2
46.0
16.4
98.7
Miles per
Passenger
1,074.1
559.9
523.5
254.6
970.8
Oi
Oi
(a) Including small certificated carriers.
Source: Reference (31).
-------
Section 14.0 - Economic Profile
Table 14-13
Air-Carrier Financial Statistics by Carrier Type, June 1997 - June 1998
Carrier
Major
% of Total
National
% of Total
Large Regional
% of Total
Medium Regional
% of Total
Small Certificated
% of Total
Commuter
% of Total
Total
Total
Passenger
Revenues
(x $1,000,000)
$74,336.4
88.6%
$5,756.0
6.9%
$636.7
0.8%
$62.5
0.1%
$2,123.2
2.5%
$1,029.8
1.2%
$83,944.6
100.0%
Total
Operating
Revenues
(x $1,000,000)
$100,506.2
86.6%
$9,837.7
8.5%
$1,706.3
1.5%
$286.5
0.2%
$2,417.8
2.1%
$1,267.3
1.1%
$116,021.8
100.0%
Total
Operating
Expenses
(x $1,000,000)
$91,436.0
85.9%
$9,454.8
8.9%
$1,686.7
1.6%
$317.8
0.3%
$2,276.1
2.1%
$1,278.4
1.2%
$106,449.8
100.0%
Operating
Profit (Loss)
(x $1,000,000)
$9,070.2
94.8%
$382.9
4.0%
$19.6
0.2%
($31.3)
-0.3%
$141.7
1.5%
($11.1)
-0.1%
$9,572.0
100.0%
Operating
Profit
Margin
(%)
9.0%
3.9%
1.1%
-10.9%
5.9%
-0.9%
8.3%
Net
Income(a)
(x $1,000,000)
$5,821.6
101.5%
($16.7)
-0.3%
($56.5)
-1.0%
($36.0)
-0.6%
$41.5
0.7%
($18.5)
-0.3%
$5,735.4
100.0%
Net Profit
Margin
(%)
5.8%
-0.2%
-3.3%
-12.6%
1.7%
-1.5%
4.9%
(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
Table 14-14
Passenger and Cargo Revenues for ATA Member Airlines, 1997
(x $1,000,000)
Airline
Number of
Aircraft
Employees
(FTEs)
Passenger
Revenues
Cargo
Revenues
Total
Operating
Revenues
%
Passenger
Revenues
Majors with Passenger Service
Alaska
America West
American
Continental
Delta
Northwest
Southwest
Trans World
United
U.S. Airways
78
103
641
388
559
405
261
184
571
376
8,016
10,195
80,321
31,705
62,934
46,753
23,749
22,930
83,324
39,734
$1,256
$1,753
$14,284
$5,686
$12,773
$8,722
$3,639
$2,924
$15,069
$7,112
$82
$51
$678
$205
$588
$788
$95
$119
$891
$177
$1,457
$1,887
$15,856
$6,361
$14,204
$9,984
$3,817
$3.328
$17,335
$8,501
86.2%
92.9%
90.1%
89.4%
89.9%
87.4%
95.3%
87.9%
86.9%
83.7%
Majors with Cargo-only Service
DHL
Federal Express
United Parcel Service (a)
27
581
214
8,564
105,649
4,349
—
—
—
$664
$5,360
$404
$1,226
$12,730
$1,863
0.0%
0.0%
0.0%
Nationals with Passenger Service
Aloha
Hawaiian
Midwest Express
17
22
24
1,901
2,357
1,689
$195
$332
$273
$30
$20
$11
$233
$404
$310
83.7%
82.2%
88.0%
Nationals with Cargo-only Service
Airborne Express
Atlas (a)
Emery (a)
Evergreen (a)
Polar Air Cargo
105
19
77
20
16
4,626
592
967
429
481
—
—
—
—
—
$890
$80
$256
$208
$288
$894
$401
$262
$256
$344
0.0%
0.0%
0.0%
0.0%
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).
14-68
-------
Table 14-15
Section 14.0 - Economic Profile
Operating Revenues, Expenses, and Profits, 1982 -1997
(in millions of dollars)
Year
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
Revenue
Passenger Miles
(x 1,000,000)
259,644
281,829
305,116
336,403
366,546
404,471
423,302
432,714
457,926
447,955
478,554
489,684
519,382
540,656
578,663
605,434
Total Op.
Revenues
$36,408
$38,954
$43,825
$46,664
$50,525
$56,986
$63,749
$69,316
$76,142
$75,158
$78,140
$84,559
$88,313
$94,578
$101,938
$109,535
Total Op.
Expenses
$37,141
$38,643
$41,674
$45,238
$49,202
$54,517
$60,312
$67,505
$78,054
$76,943
$80,585
$83,121
$85,600
$88,718
$95,729
$100,924
Total Op.
Profits
($733)
$310
$2,152
$1,426
$1,323
$2,469
$3,437
$1,811
($1,912)
($1,785)
($2,444)
$1,438
$2,713
$5,860
$6,209
$8,611
Interest
Expense
$1,384
$1,482
$1,540
$1,588
$1,693
$1,695
$1,846
$1,944
$1,978
$1,777
$1,743
$2,027
$2,347
$2,424
$1,981
$1,749
Net Profit
($916)
($188)
$825
$863
($235)
$593
$1,686
$128
($3,921)
($1,940)
($4,791)
($2,136)
($344)
$2,314
$2,804
$5,195
Operating
Profit Margin
-2.0%
0.8%
4.9%
3.1%
2.6%
4.3%
5.4%
2.6%
-2.5%
-2.4%
-3.1%
1.7%
3.1%
6.2%
6.1%
7.9%
Net Profit
Margin
-2.5%
-0.5%
1.9%
1.8%
-0.5%
1.0%
2.6%
0.2%
-5.1%
-2.6%
-6.1%
-2.5%
-0.4%
2.4%
2.8%
4.7%
Rate of
Return on
Investment
2.1%
6.0%
9.9%
9.6%
4.9%
7.2%
10.8%
6.3%
-6.0%
-0.5%
-9.3%
-0.4%
5.2%
11.9%
11.5%
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).
-------
Section 14.0 - Economic Profile
Table 14-16
Airline Operating Costs, Selected Components, 1982 - 1997
Year
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
Labor
Cost
Index
(1982=
100)
100.0
107.7
108.4
110.6
108.1
110.8
113.9
117.4
123.0
130.1
136.5
143.4
148.5
155.5
159.5
162.4
Growth
Rate
—
7.7%
0.6%
2.0%
-2.3%
2.5%
2.8%
3.1%
4.8%
5.8%
4.9%
5.1%
3.6%
4.7%
2.6%
1.8%
% Op.
Expenses
34.6%
35.5%
33.9%
33.8%
35.8%
34.7%
34.2%
33.9%
31.5%
32.4%
32.8%
33.3%
34.1%
34.4%
33.6%
33.9%
Fuel
Cost
Index
(1982=
100)
100.0
88.3
84.6
79.6
55.5
55.4
53.0
59.7
77.2
69.4
65.0
59.7
54.4
55.3
64.6
62.7
Growth
Rate
—
-11.7%
-4.2%
-5.9%
-30.3%
-0.2%
-4.3%
12.6%
29.3%
-10.1%
-6.3%
-8.2%
-8.9%
1.7%
16.8%
-2.9%
% Op.
Expenses
27.5%
24.7%
24.0%
22.3%
15.5%
15.0%
13.5%
13.9%
17.3%
14.5%
13.5%
12.4%
10.7%
11.5%
13.0%
12.5%
Aircraft Fleet (a)
Cost
Index
(1982=
100)
100.0
107.5
114.9
123.7
127.8
135.1
146.9
162.2
177.0
187.1
202.6
208.0
217.5
222.8
230.0
224.1
Growth
Rate
—
7.5%
6.9%
7.7%
3.3%
5.7%
8.7%
10.4%
9.1%
5.7%
8.3%
2.7%
4.6%
2.4%
3.2%
-2.6%
% Op.
Expenses
5.6%
6.1%
6.4%
6.8%
7.4%
7.4%
7.9%
8.0%
7.9%
8.5%
9.0%
9.2%
9.5%
9.5%
9.6%
9.0%
Interest
Cost
Index
(1982=
100)
100.0
99.0
106.3
98.0
91.8
88.7
91.9
99.4
96.0
81.4
97.3
81.2
87.6
93.5
86.9
72.1
Growth
Rate
—
-1.0%
7.4%
-7.8%
-6.3%
-3.4%
3.6%
8.2%
-3.4%
-15.2%
19.5%
-16.5%
7.9%
6.7%
-7.1%
-17.0%
% Op.
Expenses
4.0%
4.1%
3.9%
3.5%
3.5%
3.2%
3.1%
2.7%
2.6%
2.4%
2.2%
2.6%
2.8%
3.0%
2.2%
1.8%
Insurance
Cost
Index
(1982=
100)
100.0
95.7
109.3
155.3
212.0
201.8
151.7
114.5
68.2
81.3
109.3
139.4
110.8
111.6
111.5
95.4
Growth
Rate
—
-4.3%
14.2%
42.1%
36.5%
-4.8%
-24.8%
-24.5%
-40.4%
19.2%
34.4%
27.5%
-20.5%
0.7%
-0.1%
-14.4%
% Op.
Expenses
0.4%
0.4%
0.5%
0.6%
0.9%
0.8%
0.6%
0.4%
0.3%
0.3%
0.4%
0.5%
0.7%
0.7%
0.7%
0.6%
Maintenance Material
Cost
Index
(1982=
100)
100.0
101.7
108.2
119.9
147.7
153.1
166.4
176.8
190.5
193.2
177.1
166.2
157.2
153.4
169.4
191.2
Growth
Rate
—
1.7%
6.4%
10.8%
23.2%
3.7%
8.7%
6.3%
7.7%
1.4%
-8.3%
-6.2%
-5.4%
-2.4%
10.4%
12.9%
% Op.
Expenses
2.0%
2.1%
2.3%
2.5%
3.2%
3.2%
3.3%
3.2%
3.4%
3.3%
3.0%
2.9%
2.6%
2.7%
2.9%
3.2%
J^.
I
o
(a) Passenger airlines only; includes lease, aircraft, and engine rentals, depreciation, and amortization.
-------
Table 14-16 (Continued)
Section 14.0 - Economic Profile
Year
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
Landing Fees
Cost
Index
(1982=
100)
100.0
99.6
101.0
99.9
108.8
117.7
124.8
130.5
139.0
153.4
168.4
170.1
171.6
176.6
178.3
183.2
Growth
Rate
—
-0.4%
1.4%
-1.1%
8.9%
8.2%
6.0%
4.6%
6.5%
10.4%
9.8%
1.0%
0.9%
2.9%
1.0%
2.7%
% Op.
Expenses
1.7%
1.7%
1.7%
1.6%
1.8%
1.9%
1.9%
1.8%
1.8%
1.9%
2.1%
2.1%
2.0%
2.2%
2.1%
2.0%
Traffic Commission
Cost
Index
(1982=
100)
100.0
104.4
113.9
112.9
117.7
126.3
145.4
157.7
169.2
188.1
184.9
193.0
163.3
139.4
130.8
127.0
Growth
Rate
—
4.4%
9.1%
-0.9%
4.3%
7.3%
15.1%
8.5%
7.3%
11.2%
-1.7%
4.4%
-15.4%
-14.6%
-6.2%
-2.9%
% Op.
Expenses
5.9%
6.5%
7.1%
7.3%
8.1%
8.6%
9.5%
9.5%
9.4%
10.4%
10.4%
10.9%
9.6%
8.5%
7.9%
7.7%
Communications
Cost
Index
(1982=
100)
100.0
98.7
98.4
96.6
105.2
98.2
109.0
111.8
111.2
116.6
124.5
120.0
118.2
116.0
114.8
110.4
Growth
Rate
—
-1.3%
-0.3%
-1.8%
8.9%
-6.7%
11.0%
2.6%
-0.5%
4.9%
6.8%
-3.6%
-1.5%
-1.9%
-1.0%
-3.8%
% Op.
Expenses
1.5%
1.5%
1.5%
1.6%
1.8%
1.6%
1.7%
1.6%
1.4%
1.4%
1.5%
1.5%
1.5%
1.5%
1.5%
1.4%
Advertising & Promotion
Cost
Index
(1982=
100)
100.0
99.6
97.9
96.2
103.6
91.0
97.1
103.2
97.8
89.9
81.1
72.4
69.7
63.6
58.4
54.6
Growth
Rate
—
-0.4%
-1.7%
-1.7%
7.7%
-12.2%
6.7%
6.3%
-5.2%
-8.1%
-9.8%
-10.7%
-3.7%
-8.8%
-8.2%
-6.5%
% Op.
Expenses
2.2%
2.3%
2.3%
2.3%
2.5%
2.2%
2.2%
2.2%
2.0%
1.8%
1.7%
1.5%
1.5%
1.5%
1.3%
1.3%
Passenger Meals
Cost
Index
(1982=
100)
100.0
101.4
104.7
98.9
99.4
102.5
108.6
118.8
128.4
139.0
140.5
128.5
120.6
110.9
104.0
102.9
Growth
Rate
—
1.4%
3.3%
-5.5%
0.5%
3.1%
6.0%
9.4%
8.1%
8.3%
1.1%
-8.5%
-6.1%
-8.0%
-6.2%
-1.1%
% Op.
Expenses
2.9%
3.1%
3.2%
3.2%
3.4%
3.4%
3.5%
3.5%
3.5%
3.8%
3.9%
3.6%
3.5%
3.3%
3.1%
3.1%
Composite Cost
Index
Cost
Index
(1982 =
100)
100.0
101.1
102.5
102.8
99.6
101.9
105.9
112.3
122.6
126.2
128.7
130.5
129.9
131.4
136.8
137.7
Growth
Rate
—
1.1%
1.4%
0.3%
-3.1%
2.3%
3.9%
6.0%
9.2%
2.9%
2.0%
1.4%
-0.5%
1.2%
4.1%
0.7%
Source: Reference (39).
-------
Section 14.0 - Economic Profile
Table 14-17
Estimated Deicing Costs and Weather Conditions at 5 Selected Airports
Airport and Airport Characteristics
Airport A
Northern Tier
241, 436 departures, 1998
11 Major Carriers
Operational Hub
Airport B
Northeastern Tier
234,732 departures, 1998
7 Major Carriers
Operational Hub
Airport C
Semi-desert Climate
136,673 departures, 1998
9 Major Carriers
Not an Operational Hub
Airport D
Southeastern Tier
86,002 departures, 1998
8 Passenger/2 Cargo Airline
Cargo Operational Hub
Airport E
Western Arid Climate
182,667 departures, 1998
8 Passenger Airlines
Operational Hub
Deicing
Season
1996-97
1997-98
1998-99
1996-97
1997-98
1998-99
1996-97
1997-98
1998-99
1996-97
1997-98
1998-99
1996-97
1997-98
1998-99
Heating
Degree Days
7,966
6,536
6,599
4,468
3,989
4,110
1,545
1,527
1,162
4,109
3,850
3,580
4,798
5,060
5,027
Days < 32° F
165
105
91
28
7
25
5
0
2
27
19
27
34
37
36
Snowfall
(inches)
73.6
50.3
56.5
12.9
0.8
12.5
0
0
0
5.3
22.8
13.3
63.3
65.2
31.2
Deicing
Season
Departures
88,964
90,334
60,670
69,253
76,410
81,037
25,518
23,272
22,979
30,111
26,424
21,202
56,575
54,949
52,855
Reported
Deicing Cost
$26,304,455
$27,047,433
$21,507,999
$5,843,691
$7,986,294
$18,871,331
$166,211
$148,712
$182,253
$16,597,728
$14,319,099
$13,590,916
NA
$14,876,599
$7,086,810
Reported
Deicing Cost
per Departure
$296
$299
$355
$84
$105
$233
$7
$6
$8
$551
$542
$641
NA
$271
$134
J^.
I
to
Source: Reference (41).
-------
Section 14.0 - Economic Profile
Table 14-18
National Estimate of Total Deicing Costs at US Airports, 1997 -1998
Deicing Season
1996-97
1997-98
1998-99
Deicing Cost Based on:
HDD
$548,974,570
$522,624,773
$506,479,210
Days<32° F
$537,591,582
$437,407,901
$482,485,870
Snowfall
$411,725,552
$390,349,428
$415,862,888
Deicing Cost Characteristics
Average (a)
$543,283,076
$480,016,337
$494,482,540
Total Op. Costs
$95,729,000,000
$100,982,000,000
$104,034,000,000
Deicing as %
of Op. Costs
0.57%
0.48%
0.48%
Net Profits
$2,804,000,000
$5,170,000,000
$4,894,000,000
Deicing as % of
Net Profits
19.38%
9.28%
10.10%
(a)Average for HDD and Days < 32° 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
is.o 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 20°F 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 -18°F 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.
15-1
-------
Section 15.0 - Glossary
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 (BOD5) - Five-day biochemical oxygen demand. A measure of
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 20°C (see Method 405.1). BOD5 is
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.
15-2
-------
Section 15.0 - Glossary
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/anti-
icing 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).
15-3
-------
Section 15.0 - Glossary
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 55 °F).
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.
15-4
-------
Section 15.0 - Glossary
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/anti-
icing 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.
15-5
-------
Section 15.0 - Glossary
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.
MEET - 5-methyl-lH-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.
15-6
-------
Section 15.0 - Glossary
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 (K,,w) - 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.
15-7
-------
Section 15.0 - Glossary
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 cut-
off 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.
15-8
-------
Section 15.0 - Glossary
TOC - Total organic carbon. A measure of total organic content of wastewater. Unlike five-day
biochemical oxygen demand (BOD5) or chemical oxygen demand (COD), TOC is independent of
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 BOD5 and COD. TOC methods utilize heat and oxygen, ultraviolet irradiation,
chemical oxidants, or combinations of these oxidants to convert organic carbon to carbon dioxide
(CO2). The CO2 is then measured by various methods.
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 paniculate matter that is suspended in
a water sample. The measure is obtained by filtering a water sample of known volume. The
paniculate material retained on the filter is then dried and weighed, see Method 160.2.
TTZ - Tolyltriazole or 5-methyl-lH-benzotriazole. A common additive in aircraft deicing/anti-
icing 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.
15-9
-------
Section 15.0 - Glossary
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.
15-10
-------
Appendix A
SELECT U.S. AIRPORT LOCATIONS
-------
Appendix A
Select U.S. Airport Locations
Airport
Code
ILN
ALB
ANC
BWI
BIL
BDL
BUF
ORD
CVG
CLE
DFW
DAY
DIA
DSM
DTW
DLH
MKE
RFD
MCI
MEI
LGA
STL
BOS
SDF
MSP
BNA
EWR
PIT
PDX
RIC
DCA
Airport Name
Airborne Air Park
Albany International
Anchorage International
Baltimore /Washington International
Billings Logan International
Bradley International
Buffalo International
Chicago O'Hare International
Cincinnati/Northern Kentucky International
Cleveland Hopkins International
Dallas/Ft. Worth International
Dayton International
Denver International
Des Moines International
Detroit Metropolitan Wayne Country
Duluth International
General Mitchell International
Greater Rockford
Kansas City International
Key Field (Meridian)
LaGuardia
Lambert-St. Louis International
Logan International
Louisville International- Standiford Field
Minneapolis-St. Paul International
Nashville International
Newark International
Pittsburgh International
Portland International
Richmond International
Ronald Reagan Washington National
Location
Wilmington, OH
Albany, NY
Anchorage, AK
Baltimore, MD
Billings, MT
Windsor Locks, CT (services Hartford, CT/
Springfield, MA
Buffalo, NY
Chicago, IL
Covington/Cincinnati, KY/OH
Cleveland, OH
Dallas-Ft. Worth, TX
Dayton, OH
Denver, CO
Des Moines, IA
Detroit, MI
Duluth, MN
Milwaukee, WI
Rockford, IL
Kansas City, MO
Meridian, MS
New York, NY
St. Louis, MO
Boston, MA
Louisville, KY
Minneapolis-St. Paul, MN
Nashville, TN
Newark, NJ
Pittsburgh, PA
Portland, OR
Richmond, VA
Arlington, VA (services Washington, DC)
A-l
-------
Appendix A (Continued)
Airport
Code
SEA
SLC
SYR
PVD
ITH
HTS
HPN
IAD
Airport Name
Seattle-Tacoma International
Salt Lake City International
Syracuse Hancock International
T.F. Green
Tomkins County
Tri- State (Huntington)
Westchester County
Washington Dulles International
Location
Seattle, WA
Salt Lake City, UT
Syracuse, NY
Providence, RI
Ithaca, NY
Huntington, WV
Whrte Plarns, NY
Chantilly, VA (services Washington DC)
A-2
-------
Appendix B
MEAN ANNUAL SNOWFALL (THROUGH 1995)
FOR SELECT U.S. CITIES
-------
Appendix B
Mean Annual Snowfall (Through 1995) for Select U.S. Cities
City, State
VALDEZ, AK
MT. WASHINGTON, NH
YAKUTAT, AK
MARQUETTE, MI
SAULT STE. MARIE, MI
TALKEETNA, AK
SYRACUSE, NY
CARIBOU, ME
LANDER, WY
JUNEAU, AK
FLAGSTAFF, AZ
MUSKEGON, MI
MCGRATH, AK
BUFFALO, NY
ROCHESTER, NY
ERIE, PA.
ALPENA, MI
BINGHAMTON, NY
BETTLES,AK
CASPER, WY
DULUTH, MN
BURLINGTON, VT
KODIAK, AK
ELKINS, WV
HOUGHTONLAKE,MI
GRAND RAPIDS, MI
SHERIDAN, WY
SOUTH BEND, IN
PORTLAND, ME
ANCHORAGE, AK
FAIRBANKS, AK
WORCESTER, MA
Mean Annual Snowfall (in.)
325.8
253.9
197.6
130.6
117.1
115.0
114.7
110.7
102.2
100.7
100.3
97.9
94.2
91.8
90.3
86.5
85.7
82.8
82.5
79.1
78.9
78.0
77.4
76.7
75.0
71.8
71.7
70.9
70.8
70.0
69.5
67.6
B-l
-------
Appendix B (Continued)
City, State
INTERNATIONAL FALLS, MN
KALISPELL, MT
ALBANY, NY
CONCORD, NH
COLD BAY,AK
DENVER, CO
BECKLEY, WV
BLUE HILL, MA
NOME, AK
GREAT FALLS, MT
HOMER, AK
SALT LAKE CITY, UT
ST. PAUL ISLAND, AK
BILLINGS, MT
YOUNGSTOWN, OH
CLEVELAND, OH
CHEYENNE, WY
GULKANA,AK
MINNEAPOLIS-ST.PAUL, MN
SPOKANE, WA
BETHEL, AK
LANSING, MI
ANNETTE, AK
ELY, NV
ROCHESTER, MN
AVOCA, PA
HARTFORD, CT
KOTZEBUE, AK
AKRON, OH
MILWAUKEE, WI
HELENA, MT
GREEN BAY, WI
KING SALMON, AK
MISSOULA, MT
Mean Annual Snowfall (in.)
64.6
63.9
63.8
63.5
60.8
60.3
60.0
59.5
58.8
58.4
57.7
57.7
56.7
56.3
56.1
55.7
55.4
50.7
49.5
49.5
49.4
49.0
48.9
48.9
48.6
48.1
47.9
47.6
47.4
47.2
47.0
46.7
46.1
45.5
B-2
-------
Appendix B (Continued)
City, State
FLINT, MI
SAINT CLOUD, MN
MADISON, WI
BIGDELTA,AK
DUBUQUE,IA
PITTSBURGH, PA
POCATELLO, ID
BISMARCK, ND
LA CROSSE, WI
COLORADO SPRINGS, CO
MANSFIELD, OH
WILLIAMSPORT, PA
BOSTON, MA
SCOTTSBLUFF, NE
DETROIT, MI
BURNS,OR
HURON, SD
SIOUX FALL S, SD
WILLISTON, ND
RAPID CITY, SD
FARGO, ND
CHICAGOJL
GOODLAND, KS
UNALAKLEET, AK
ELKO, NV
TOLEDO, OH
ABERDEEN, SD
ROCKFORD, IL
PROVIDENCE, RI
MIDDLETOWN/HARRISBURG INTL APT
ALAMOSA, CO
PUEBLO, CO
VALENTINE, NE
DBS MOINES, IA
Mean Annual Snowfall (in.)
45.2
44.9
43.9
43.8
43.6
43.5
42.7
42.7
42.5
42.3
42.1
41.9
41.7
41.5
41.3
41.3
40.1
40.1
39.5
39.4
38.9
38.2
38.2
38.0
37.6
37.0
36.5
35.9
35.9
35.0
33.9
33.5
33.5
33.3
B-3
-------
Appendix B (Continued)
City, State
CHARLESTON, WV
FORT WAYNE, IN
WATERLOO, IA
ALLENTOWN, PA
SIOUX CITY, IA
OMAHA (NORTH), NE
GRAND ISLAND, NE
NORFOLK, NE
MOLINE, IL
NORTH PLATTE, NE
OMAHA EPPLEY AP, NE
NEW YORK C.PARK, NY
BARROW, AK
COLUMBUS, OH
GLASGOW, MT
DAYTON, OH
NEWARK, NJ
LINCOLN, NE
HUNTINGTON, WV
NEW YORK (LAGUARDIA AP), NY
BRIDGEPORT, CT
PEORIA, IL
GRAND JUNCTION, CO
RENO, NV
YAKIMA, WA
WINNEMUCCA, NV
GREATER CINCINNATI AP
SPRINGFIELD, IL
COLUMBIA, MO
INDIANAPOLIS, IN
NEW YORK (JFK AP), NY
JACKSON, KY
ROANOKE, VA
WASHINGTON DULLES AP, D.C.
Mean Annual Snowfall (in.)
33.1
32.8
32.3
32.1
31.7
31.2
30.5
30.5
30.4
30.4
29.8
28.3
28.2
27.9
27.7
27.7
27.5
26.8
26.0
25.8
25.5
24.8
24.7
24.4
23.6
23.5
23.4
23.1
23.1
22.9
22.9
22.8
22.5
22.3
B-4
-------
Appendix B (Continued)
City, State
CLAYTON, NM
CONCORDIA, KS
TOPEKA, KS
PHILADELPHIA, PA
BOISE, ID
ISLIP, NY
BALTIMORE, MD
WILMINGTON, DE
DODGE CITY, KS
KANSAS CITY, MO
ST. LOUIS, MO
PENDLETON, OR
LYNCHBURG, VA
SPRINGFIELD, MO
OLYMPIA, WA
WASHINGTON NAT'L AP, D.C.
LOUISVILLE, KY
LEWISTON, ID
LEXINGTON, KY
WICHITA, KS
ATLANTIC CITY AP, NJ
BRISTOL -JHNSN CTY-KNGSPRTJN
AMARILLO, TX
ASHEVILLE, NC
RICHMOND, VA
EVANSVILLE, IN
QUILLAYUTE, WA
KNOXVILLE, TN
SEATTLE SEA-TAC AP, WA
ROSWELL, NM
ALBUQUERQUE, NM
PADUCAHKY
WINSLOW, AZ
NASHVILLE, TN
Mean Annual Snowfall (in.)
22.0
21.6
20.8
20.8
20.7
20.5
20.4
20.3
19.9
19.9
19.5
17.7
17.7
17.2
16.8
16.4
16.1
15.8
15.8
15.7
15.7
15.4
15.0
14.9
13.7
13.6
13.0
11.6
11.3
11.1
10.8
10.6
10.5
9.9
B-5
-------
Appendix B (Continued)
City, State
LUBBOCK, TX
OAK RIDGEJN
TULSA, OK
OKLAHOMA CITY, OK
GREENSBORO- WNSTN-SALM-HGHPT,NC
WALLOPS ISLAND, VA
BISHOP, CA
NORFOLK, VA
MEDFORD, OR
RALEIGH, NC
SEATTLE C.O., WA
SALEM, OR
PORTLAND, OR
NORTH LITTLE ROCK, AR
EUGENE, OR
FORT SMITH, AR
GREENVILLE-SPARTANBURG AP, SC
WICHITA F ALL S, TX
CHARLOTTE, NC
EL PASO, TX
LITTLE ROCK, AR
MEMPHIS, TN
ABILENE, TX
ASTORIA, OR
CHATTANOOGA, TN
MIDLAND-ODESSA, TX
REDDING, CA
TUPELO, MS
SANANGELO, TX
HUNTSVILLE, AL
DALLAS-FORT WORTH, TX
ATHENS, GA
ATLANTA, GA
CAPE HATTERAS, NC
Mean Annual Snowfall (in.)
9.9
9.5
9.4
9.2
8.5
8.4
8.2
7.4
7.2
6.9
6.8
6.6
6.5
6.3
6.3
6.2
5.9
5.7
5.4
5.3
5.1
5.1
4.6
4.3
4.3
4.2
2.9
2.9
2.9
2.7
2.5
2.4
2.0
1.9
B-6
-------
Appendix B (Continued)
City, State
WILMINGTON, NC
COLUMBIA, SC
BIRMINGHAM AP,AL
SHREVEPORT, LA
WACO, TX
TUCSON, AZ
MERIDIAN, MS
LAS VEGAS, NV
AUGUSTA,GA
MACON, GA
JACKSON, MS
AUSTIN, TX
DEL RIO, TX
CHARLESTON AP,SC
SAN ANTONIO, TX
COLUMBUS, GA
MOBILE, AL
MONTGOMERY, AL
SAVANNAH, GA
HOUSTON, TX
LAKE CHARLES, LA
PORT ARTHUR, TX
EUREKA, CA.
PENSACOLA, FL
BATON ROUGE, LA
NEW ORLEANS, LA
FRESNO, CA
VICTORIA, TX
SANTA BARBARA, CA
FORT MYERS, FL
KEY WEST, FL
MIAMI, FL
HILO, HI
HONOLULU,HI
Mean Annual Snowfall (in.)
1.9
1.7
1.5
1.5
1.4
1.2
1.2
1.2
1.1
0.9
0.9
0.9
0.9
0.7
0.7
0.5
0.4
0.4
0.4
0.4
0.3
0.3
0.2
0.2
0.2
0.2
0.1
0.1
0
0
0
0
0
0
B-7
-------
Appendix B (Continued)
City, State
KAHULUI, HI
LIHUE, HI
GUAM, PC
KOROR, PC
KWAJALEIN, MARSHALL IS., PC
MAJURO, MARSHALL IS, PC
PAGO PAGO, AMER SAMOA, PC
POHNPEI, CAROLINE IS., PC
CHUUK, E. CAROLINE IS., PC
WAKE ISLAND, PC
YAP, W CAROLINE IS., PC
Mean Annual Snowfall (in.)
0
0
0
0
0
0
0
0
0
0
0
Source: National Oceanic Atmospheric Administration.
B-8
-------
Appendix C
CLIMATE CONTOUR MAP OF THE U.S.
-------
U. S. DEPARTMENT OF COMMERCE
ENVIRONMENTAL SCIENCE SERVICES ADMINISTRATION
MEAN ANNUAL TOTAL SNOWFALL (Inches)
CLIMATIC MAPS
OF THE
UNITED STATES-
MEAN SNOWFALL Cinches) - Cont'd
(Selected Stations)
MICH. - HOUGHTON 178
N. Y. - BOONVILLE 207
PA. - KANE 107
W. VA.- KUMBRABOW STATE FOREST 126
X. C. . MT. MITCHELL 60
PARKER 47
MAINE- GREENVILLE 111
N. H. - HT. WASHINGTON 198
FIRST CONNECTICUT LAKE 172
VT. .- SOMERSET 114
/^HASS. - WEST CUMMINGTON 85
NORFOLK 93
MEAN SNOWFALL (inches)
fSelected Stations)
CAUTION SHOULD BE USED IK
INTERPOLATING ON THESE GEN-
ERALIZED MAPS, PARTICULARLY
IN MOUNTAINOUS AREAS.
DATA BASED ON PERIOD OF
RECORD THROUGH 1960.
IDAHO
NEV.
UTAH
ARIZ.
MONT.
-------
Appendix D
SELECTED FINANCIAL AND SCHEDULED SERVICE TRAFFIC STATISTICS
-------
U.S. Large Certificated Air Carriers, 1997 - 1998
Air Carrier
12 month period ending 6/30/98
Operating
Revenues
Net
Income
Passenger
Enplane-
ments
(x 1,000)
Revenue
Passenger
Miles
(x 1,000)
Available
Seat Miles
(x 1,000)
Passenger
Ton-miles
(x 1,000)
Cargo
Ton-miles
(x 1,000)
HQ
State
Notes [3]
Majors
Alaska
America West
American
Continental
Delta
DHL Airways
Federal Express
Northwest
Southwest
Trans World
United
United Parcel
US Airways
$1,527,189
$1,938,366
$16,229,821
$6,870,111
$14,328,259
$1,284,853
$13,414,818
$9,881,713
$3,994,409
$3,370,128
$17,329,571
$1,842,455
$8,494,535
$105,841
$102,971
$1,017,980
$427,490
$1,000,505
($32,962)
$441,887
$536,386
$376,467
($60,897)
$924,935
($22,203)
$1,003,208
12,548
17,826
81,192
40,150
104,050
0
0
54,506
57,286
24,112
84,500
0
57,869
9,900,889
15,969,799
107,640,234
47,639,667
101,056,563
0
0
72,408,489
29,935,657
25,510,913
121,683,332
0
41,051,381
14,743,618
23,772,818
154,188,327
66,422,995
139,995,366
0
0
97,219,704
45,978,282
36,025,463
170,943,723
0
56,773,242
1,073,610
1,596,980
10,764,023
4,763,967
10,105,656
0
0
7,240,849
2,993,566
2,551,092
12,168,333
0
4,105,139
77,693
113,748
2,053,551
737,402
1,744,996
358,264
6,518,002
2,226,434
131,828
310,055
2,972,682
895,094
349,414
Nationals
Air Transport Int'l
Air Wisconsin
Air Trans [2]
Valuejet
Aloha
American Eagle [3, 4]
Flagship
Simmons
Wings West
American Int'l.
American Trans Air
Arrow
Atlantic Southwest
Atlas
Carnival
Challenge Air Cargo
Continental Express [4]
Continental Micronesia
Emery
Evergreen
Executive [4]
Frontier
Hawaiian
$117,749
$155,265
$197,217
$183,424
$235,350
$645,073
$437,568
$824,896
$89,363
$396,451
$392,674
$63,299
$134,928
$516,630
$670,352
$556,661
$274,871
$96,138
$155,474
$409,838
$8,911
$3,917
($3,407)
($70,179)
$6,526
$33,198
($17,166)
$28,663
($19,941)
$57,804
$30,782
($28,063)
$2,713
$50,918
($28,163)
($7,389)
($4,172)
$4,142
($15,226)
$2,008
0
2,045
2,261
2,339
5,312
6,829
0
3,776
0
3,876
0
971
0
5,261
2,432
0
0
1,446
1,348
4,934
0
645,827
1,494,612
1,203,597
734,974
1,477,972
0
5,259,538
0
976,055
0
1,052,291
0
1,358,487
4,206,328
0
0
276,806
1,104,154
3,152,308
0
1,025,905
2,487,706
2,392,198
1,112,337
2,423,606
0
7,163,577
0
1,818,538
0
1,554,150
0
2,355,329
6,178,542
0
0
463,382
1,945,860
4,357,865
0
64,583
149,461
120,396
73,498
147,797
0
525,954
0
97,605
0
105,229
0
135,849
420,633
0
0
27,681
110,415
315,231
0
521
947
2,153
9,416
606
82,314
0
96,540
611
0
1,525
215,969
536
134,949
0
538,171
10
5,262
56,782
AR
WI
FL
HI
TX
MI
IN
FL
GA
NY
FL
FL
TX
HI
CA
OR
PR
CO
HI
NSS
NSS
NSS
D-l
-------
U.S. Large Certificated Air Carriers, 1997 - 1998 (Continued)
Air Carrier
Horizon Air [4]
Midway
Midwest Express
Polar Air Cargo
Reno
Southern Air
Sun Country
lower
Trans States
US Air Shuttle
World
12 month period ending 6/30/98
Operating
Revenues
$322,395
$197,415
$333,483
$337,239
$392,027
$124,336
$245,899
$487,212
$211,165
$173,664
$289,588
Net
Income
$10,688
$13,471
$30,046
($30,155)
($12,791)
($31,641)
($4,772)
($8,876)
$24,990
$5,987
($4,359)
Passenger
Enplane-
ments
(x 1,000)
3,930
1,538
1,747
0
5,248
0
0
1,459
2,370
1,516
0
Revenue
Passenger
Miles
(x 1,000)
980,848
842,662
1,498,079
0
2,830,249
0
0
3,920,610
480,040
302,491
0
Available
Seat Miles
(x 1,000)
1,590,185
1,300,572
2,323,706
0
4,428,320
0
0
5,162,146
935,877
685,793
0
Passenger
Ton-miles
(x 1,000)
98,085
84,266
149,808
0
283,025
0
0
392,061
48,004
30,249
0
Cargo
Ton-miles
(x 1,000)
3,469
763
18,442
1,113,913
5,412
0
0
97,895
0
294
0
HQ
State
WA
NC
WI
CA
NV
OH
MN
NY
MO
NY
VA
Notes [3]
NSS
NSS
NSS
Large Regionals
Amerijet
Champion
Express One
Fine
Florida West
Gemini Air Cargo
Kitty Hawk
Kiwi
Mesaba
Miami Air
Morth American
Northern Air
Pan American
Reeve
Ryan Int'l.
Spirit
Sun Pacific
FransMeridian
UFS
USA Jet
Vanguard
^antop
$71,817
$53,565
$111,552
$87,610
$64,267
$95,472
$117,667
$73,447
$303,270
$78,399
$60,665
$40,918
$38,264
$29,827
$110,568
$102,661
$11,785
$29,682
$57,689
$76,188
$84,907
$12,138
$4,033
($26,456)
($1,910)
($6,575)
$2,724
$11,488
$7,701
($22,084)
$21,862
$1,278
$1,467
$4,112
($20,119)
($2,230)
$4,547
$3,909
$287
($2,337)
$1,063
$4,700
($17,411)
($1,892)
0
0
0
0
0
0
0
609
3,749
0
0
0
333
57
0
1,088
0
0
670
0
1,078
0
0
0
0
0
0
0
0
558,891
926,228
0
0
0
538,284
35,607
0
871,324
0
0
106,306
0
674,740
0
0
0
0
0
0
0
0
988,784
1,708,509
0
0
0
795,823
83,619
0
1,109,572
0
0
211,065
0
1,088,814
0
0
0
0
0
0
0
0
55,889
92,623
0
0
0
53,828
3,561
0
87,132
0
0
10,631
0
67,474
0
97,520
0
0
0
65,263
0
0
914
279
0
0
17,890
9,615
4,002
0
0
0
0
0
0
846
0
FL
MN
TX
FL
FL
DC
TX
NJ
MN
FL
NY
AK
FL
AK
KS
MI
AZ
GA
MO
MI
MO
MI
NSS
NSS
NSS
NSS
NSS
Chap. 11
NSS
NSS
NSS
NSS
NSS
NSS
NSS
Small Regionals
Capital Cargo
Casino Express
Custom Air
$16,920
$15,692
$10,388
$375
($2,676)
($146)
0
205
0
0
201,846
0
0
239,369
0
0
20,184
0
0
0
0
FL
NV
FL
NSS
D-2
-------
U.S. Large Certificated Air Carriers, 1997 - 1998 (Continued)
Air Carrier
Eastwind
Falcon
Lynden Air Cargo
Nations Air
Omni
Pace
Panagra
Pro Air
Renown
Sierra Pacific
Sunworld
Tatonduk
Trade winds
Trans Continental
Trans-Air-Link
Winair
12 month period ending 6/30/98
Operating
Revenues
$22,641
$13,955
$20,395
$6,724
$24,955
$4,914
$3,610
$11,247
$8,599
$6,650
$7,696
$7,248
$14,965
$22,719
$1,930
$4,939
Net
Income
($8,684)
$1,265
($5,761)
$299
$1,141
$256
($1,071)
($18,849)
($1,033)
$631
($914)
$1,127
($665)
$1,172
($220)
($1,150)
Passenger
Enplane-
ments
(x 1,000)
240
0
0
0
0
0
161
0
0
19
NA
0
0
0
0
Revenue
Passenger
Miles
(x 1,000)
102,118
0
0
0
0
0
73,399
0
0
27,234
453
0
0
0
0
Available
Seat Miles
(x 1,000)
308,701
0
0
0
0
0
308,727
0
0
57,486
1,784
0
0
0
0
Passenger
Ton-miles
(x 1,000)
10,212
0
0
0
0
0
7,340
0
0
2,723
45
0
0
0
0
Cargo
Ton-miles
(x 1,000)
0
0
6,527
0
0
0
0
0
0
0
0
39
0
0
0
0
HQ
State
NC
FL
AK
GA
OK
NC
FL
WA
CA
AZ
KY
AK
NC
MI
FL
UT
Notes [3]
NSS
NSS
NSS
NSS
NSS
NSS
PNSS
6mos.
NSS
NSS
6mos.
[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-3
-------
U.S. Small Certificated and Commuter Airlines, 1997 -1998
Air Carrier
12 month period ending 6/30/98
Passenger
Enplane-
ments
(x 1,000)
Revenue
Passenger
Miles
(x 1,000)
Available Seat
Miles
(x 1,000)
Passenger
Ton-miles
(x 1,000
Cargo
Ton-miles
(x 1,000)
Code-
Sharing [1]
HQ
State
Fourth Quartile
Comair
Mesa
5,005,338
4,151,202
1,883,205
1,044,158
3,048,664
1,856,093
188,320,481
104,415,813
Y
Y
OH
NM
Third Quartile
Allegheny [3]
Piedmont [3]
Sky West
2,029,870
2,906,282
3,212,231
377,435
585,507
772,072
749,700
1,026,577
1,484,829
37,743,527
58,550,692
77,207,248
200,897
285,102
Y
Y
Y
PA
NC
UT
Second Quartile
Atlantic Coast
Business Express
CCAir
Express Airlines I [3]
PSA [3]
Westair
1,854,888
1,290,122
776,663
1,291,814
1,190,126
1,467,951
584,279
283,542
141,304
369,664
393,392
231,378
1,085,484
741,247
254,142
618,605
611,206
391,277
58,427,900
28,340,677
14,130,398
36,966,354
39,239,146
23,137,785
2,587
1
Y
Y
Y
Y
Y
VA
NH
NC
TX
CA
First Quartile
Action
Air Midwest
Air Nevada
Air St. Thomas
Air Sunshine
Air Vegas
Alaska Seaplane Service
Aloha Island
Alpine Air
Astral Aviation
Austin Express [2]
Baker Aviation
Bemidji
Bering Air
Big Sky
Cape Air
Cape Smythe Air
Casino [2]
Chautauqua
Coastal Air Transport
Colgan Air
Commutair
Corporate Flight Management
1,670
474,024
41,536
11,071
26,860
117,528
2,513
470,637
6,129
291,822
3,322
17,840
25
45,699
43,118
388,348
43,712
2,632
704,775
2,409
97,225
630,827
160,177
103
91,841
7,488
1,032
3,278
21,425
152
31,407
1,056
71,791
701
1,352
5
6,178
9,163
21,212
5,704
190,299
157,891
361
16,506
117,374
37,189
156
199,493
9,665
1,877
7,449
29,581
680
53,727
4,744
161,175
3,671
5,256
102
15,602
29,637
41,717
14,826
1,199,470
317,604
520
51,620
271,088
86,824
10,281
9,184,096
748,751
103,189
327,750
2,142,549
14,510
3,140,677
105,640
7,179,148
70,120
135,229
500
617,784
43,118
2,121,183
570,416
19,029,892
15,789,078
36,135
1,461,525
11,737,425
3,718,930
5,865
3
100,167
42
97,590
24,119
243,102
10,209
8,464
299,202
56,232
723
133,493
1,322
Y
Y
Y
Y
KS
HI
AK
WI
AK
AK
MT
AK
D-4
-------
U.S. Small Certificated and Commuter Airlines, 1997 - 1998 (Continued)
Air Carrier
lagle Canyon
illis Air Taxi
ira Aviation
ixec Express II
'lying Boat
?orty-Mile Air
"reedom Air
"rentier Flying Service
7.S. Air Service
Grand Canyon Helicopters
Grant Aviation
Great Lakes Aviation
Gulf Air Taxi
Gulfstream Int'l.
rlageland Aviation
rlaines
rlarbor
liamna Air Taxi
island Express
lim Air
iatmai Air [2]
ienmore Air Harbor
Carry's Flying Service
^as Vegas
^.A.B. Flying Service
VIerlin Express
••Jew England
Olson Air Service
Dacific Island
Daradise Island
Deninsula
Pine State
Dro Air
Dromech
Redwing
Samoa Aviation
Scenic
Seaborne Aviation
12 month period ending 6/30/98
Passenger
Enplane-
ments
(x 1,000)
199,079
400
418,640
227,333
35,413
2,367
77,201
37,548
1,203
1,156
20,692
668,149
242
583,118
54,098
22,874
63,956
450
15,164
860
8,348
51,974
7,569
8,340
32,966
52,216
25,031
4,883
89,895
242,066
179,334
1,545
160,602
18,667
2,566
71,675
286,418
63,275
Revenue
Passenger
Miles
(x 1,000)
35,834
52
51,950
99,198
3,180
176
2,557
9,471
152
70
3,288
195,734
23
111,145
5,171
762
4,499
10
2,888
144
275
4,155
990
749
2,215
15,423
426
423
5,455
42,612
45,976
390
73,399
661
331
6,972
49,861
2,385
Available Seat
Miles
(x 1,000)
50,227
200
104,071
249,878
5,213
1,031
12,438
26,572
772
113
10,858
395,072
108
205,692
15,364
1,607
13,908
261
6,417
629
511
7,730
5,353
1,077
3,477
42,272
958
2,736
10,613
75,957
99,724
1,319
308,727
2,166
1,598
10,244
67,382
3,637
Passenger
Ton-miles
(x 1,000
3,583,422
4,175
5,195,049
9,919,828
318,004
17,650
255,721
947,058
15,168
6,960
328,834
19,573,445
1,644
11,114,522
517,134
76,212
449,920
1,041
288,756
14,425
27,549
415,515
98,956
74,944
221,480
1,542,263
25,031
42,229
545,524
4,261,205
4,597,570
39,013
7,339,767
66,082
33,101
696,949
4,986,054
238,547
Cargo
Ton-miles
(x 1,000)
1,441
385,973
116,142
20,927
35,783
476,619
10,253
77
112,466
1,198
1,023,024
285,006
38,680
3,837
12,941
17,266
27,635
1,334
99,270
2,191
99,285
116,986
559
40,192
545,524
320,674
2
17,697
8,576
Code-
Sharing [1]
Y
Y
Y
Y
Y
Y
HQ
State
NV
AK
TX
AK
AK
AK
AK
AK
AK
AK
AK
AK
AK
AK
AK
AK
WA
AK
AK
D-5
-------
U.S. Small Certificated and Commuter Airlines, 1997 - 1998 (Continued)
Air Carrier
Skagway Air Service
Southcentral Air
Springdale Air
Sunrise [2]
Fanana Air Service
Faquan Air Service
Viesques Air Link
Village Aviation
Warbelow's Air Ventures
Ward Air
West Isle Air
Wings of Alaska
Wright Air Service
Yute Air Alaska
12 month period ending 6/30/98
Passenger
Enplane-
ments
(x 1,000)
10,099
42,158
1,065
448
4,329
113,304
76,815
196
32,418
43
26,436
29,234
10,755
74,223
Revenue
Passenger
Miles
(x 1,000)
803
2,873
154
59
369
3,375
2,434
1
6,855
1
1,029
1,414
1,729
5,804
Available Seat
Miles
(x 1,000)
1,711
10,258
456
226
2,612
17,500
3,934
22
17,724
9
2,602
4,454
5,139
17,410
Passenger
Ton-miles
(x 1,000
80,292
287,285
15,443
5,869
36,912
312,398
243,366
112
685,543
96
102,925
141,358
172,850
580,351
Cargo
Ton-miles
(x 1,000)
15,849
65,777
2,668
70,118
147,036
251
584,609
25
976
35,725
81,796
237,778
Code-
Sharing [1]
HQ
State
AK
AK
AK
AK
AK
AK
AK
AK
AK
[1] Carrier has code-sharing arrangements with one or more major airlines;
source: RAA website: httpVwww.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)
D-6
------- |