CONTRACTOR REPORT GUIDANCE FOR ISSUING NPOES STORM WATER PERMITS FOR AIRPORTS SEPTEMBER 28, 1990 Prepared for: Permits Division U.S. Environmental Protection Agency 401 M Street, S.W. Washington, D.C. 20460 Prepared by: ERC Environmental and Energy Services Co, 11260 Roger Bacon Drive Reston, VA 22090 ------- FOREWORD This Contractor Report was prepared for the U.S. Environmental Protection Agency under Contract No. 68-03-3410. The primary authors are John P. Whitescarver and Kenneth M. Mackenthun. This report does not necessarily represent the views and opinions of the U.S. Environmental Protection Agency. This report results from a review of selected literature, reports, and FAA Advisory Circulars; telephone interviews with many people, including persons in Canada, France, Norway, and Sweden; personal visitations with several persons; and the experience of the authors. The mention of corporate or proprietary names or products does not constitute endorsement by the U.S. Environmental Protection Agency or the contractor. ii ------- ACKNOWLEDGMENTS There were many who gave willingly of their time, talents, and knowledge in providing information and other services to make this report possible. Space allows mention of only a few of those deserving to be mentioned here. For information generously supplied, the authors gratefully acknowledge Bill McCracken, State of Michigan; Richard Laux, State of Missouri; Dan Halton, State of New York; Rob Sulski, State of Illinois; Ken Wiesner, State of Wisconsin; Jim Grier, State of Connecticut; Dave Nelson, State of Minnesota; Horacio Tablada, State of Maryland; Dennis Dobyns, Reno, Nevada; Roberta Ellis, Massport, Boston, Massachusetts; Heather Stockart, Anchorage, Alaska; Miles Carter, Stapleton Airport, Denver, Colorado; Dan Salvano and George Legaretta, Federal Aviation Administration; Art Kosatka, Airport Operations Council International; Don Collier and Colleen Quinn, Air Transport Association of America; Karl Hoenke and Dean Anderson, Chevron Chemical Company; Bill Foshee, Dow Chemical Company; and Bernt Lidstrom, Deicing Systems. No report is complete without sound editorial services and for these our thanks to Margaret Laughlin, ERC Environmental and Energy Services Company. iii ------- TABLE OF CONTENTS Page FOREWORD ii ACKNOWLEDGMENTS iii SECTION 1. INTRODUCTION 1-1 BACKGROUND 1-1 AIRPORT OPERATIONS 1-1 Airplane Maintenance 1-2 Airplane Cleaning 1-3 Vehicle Maintenance 1-3 Vehicle Washing 1-3 Fire Training Facilities 1-4 Storage and Transfer Areas 1-4 Airplane Servicing 1-4 Airplane Deicing 1-5 Runway and Ramp Deicing 1-6 RESPONSIBLE PARTIES 1-6 SECTION 2. STATEMENT OF THE PROBLEM 2-1 NEED FOR DEICERS 2-1 DEICERS USED 2-2 Airplanes 2-2 Runways and Taxiways 2-3 DEICER QUANTITIES USED 2-4 ENVIRONMENTAL EFFECTS 2-6 CASE HISTORIES 2-8 REFERENCES CITED 2-13 iv ------- TABLE OF CONTENTS (Cont'd) Page SECTION 3. AIRSIDE DEICING AND ANTI-ICING MATERIALS . . 3-1 AIRPLANES 3-1 Airplane Deicing 3-1 Freezing Point Depressant Fluids 3-1 Ethylene Glycol 3-2 Propylene Glycol 3-4 Type I and Type II Fluids 3-5 RUNWAYS AND TAXIWAYS 3-6 Runway Deicing 3-6 Chemicals Used 3-6 Urea 3-7 Ethylene Glycol 3-8 Calcium Magnesium Acetate Product (CMA/MCA) 3-8 Chemicals Under Investigation 3-9 REFERENCES CITED 3-10 SECTION 4. CONTROL OPTIONS 4-1 FUTURE TRENDS 4-1 MANAGEMENT PRACTICES . .' 4-2 TREATMENT AND DISPOSAL 4-3 Disposal to Sanitary Sewage Facility 4-3 Treatment in a Biological Oxidation Facility . 4-3 Lagoons, Detention, and Retention Ponds . . . 4-4 Land Disposal 4-5 Recycling 4-5 Reduction in Chemical Usage 4-6 CANADIAN EXPERIENCE 4-6 REFERENCES CITED 4-9 ------- TABLE OF CONTENTS (Cont'd) Page SECTION 5. NPDES PERMIT 5-1 PERMIT APPLICATION 5-2 PERMIT ISSUANCE 5-3 PERMIT CONDITIONS 5-4 STORM WATER MANAGEMENT (SWM) PLAN 5-5 PROHIBITIONS 5-9 vi ------- SECTION 1 INTRODUCTION BACKGROUND Section 402(p) of the Clean Water Act (CWA) requires EPA to develop permit application requirements and issue permits for storm water discharges associated with industrial activity. On December 1, 1988, EPA published a notice of proposed rulemaking that defined the term "storm wa'ter discharge associated with industrial activity" to include storm water discharges from airports which have "vehicle maintenance shops, material handling facilities, equipment cleaning operations, or airport deicing operations." Reports from various sources tend to show that major sources of pollutants in storm water discharges from airports result from airplane and ground vehicle maintenance, airplane and ground vehicle cleaning, transport and storage of fuels and other petroleum products, and deicing of airplanes and runways. AIRPORT OPERATIONS Airport operations are usually divided into airside and ground- side operations, which frequently are separate but operate under the same airport "authority" at large airports. This report addresses only the airside operation and will focus on airplane deicing and runway deicing. Groundside operations may have contaminated storm water runoff that is subject to NPDES regulations; however, this is typical of other commercial facilities and similar to shopping centers. Groundside operations subject to storm water regulatory requirements include parking lots; construction operations and 1-1 ------- support facilities, including gasoline service stations, automobile rental facilities, and vehicle repair facilities (groundside vehicles); hotels; and restaurants. Each of these may have parking lots, fuel, lubricant, and solvent storage and maintenance.facilities subject to the storm water regulations. Airside operations are more specialized and therefore are subject to categorization. Several operations may have process wastewater that is treated and/or discharged directly to a publicly owned treatment works (POTW). This guidance addresses storm water discharges only which may be contaminated by industrial activities. These activities may include: 1. Airplane maintenance 2. Airplane cleaning 3. Vehicle maintenance 4. Vehicle washing 5. Fire training facilities 6. Storage areas Tank farm spillage Deicing fluids spillage 7. Airplane servicing Engine oil Hydraulic fluid Lavatory fluids Fuel Potable water 8. Airplane deicing 9. Runway and ramp deicing Airplane Maintenance Airplane maintenance takes place at two locations: the airline maintenance facility, or the ramp area adjacent to the passenger 1-2 ------- terminal. The ramp area normally drains to storm sewers. Ramp maintenance can result in minor spills of fuel oil and hydraulic fluids. If not cleaned up, the fluids are washed into the storm sewer system by rain or snow melt. These spills frequently are cleaned up using absorptive material such as sawdust. Where the ramp area has unsealed cracks, spillage can contaminate the underlying soil and may result in ground water contamination. Airplane Cleaning Airplanes normally are washed at major maintenance facilities, where washing is scheduled along with routine maintenance checks. The spent wash water is contaminated with surface dirt, metals from the airplane skin, and airplane fluids (fuel, hydraulic fluid, oil, lavatory waste). Vehicle Maintenance Airport vehicles are maintained by each tenant, and are frequently repaired and serviced on airport property. As a result, there is a potential for illicit discharges of oils, solvents, lubricants, fuel and antifreeze. Inspection of the facility may indicate the need to close the floor drain and to establish procedures to prevent improper disposal of fluids. Vehicle Washing t EPA regulations prohibit the discharge of wash water from car and truck cleaning facilities without a permit. The discharge requires treatment' for the removal of solvents, soaps and solids prior to discharge. 1-3 ------- Fire Training Facilities These facilities are frequently found at large airports and should be designed to retain fire fighting fluids. These facilities should be regulated separately for storm water permits; however, a storm event may wash the area and cause the discharge of retained fire fighting fluids. Storage and Transfer Areas Outdoor storage of petroleum substances are a major environmental problem at airports. Underground storage tanks (UST) are sources of leaks and are being monitored and replaced as appropriate. Storm water discharges have a potential for being contaminated during the remediation process, during normal transfer and during maintenance. Above ground storage tanks are even more likely to contaminate storm water. One airport in New York was required to cover the tanks with a roof to prevent storm water contamination. Most airports have plans to minimize the potential for contamination. These are spill prevention and countermeasure plan, (SPCC Plan), hazardous materials control plan and UST management plan. These documents can be useful in evaluating the need for a storm water management plan for the tank storage areas or the entire airport. Airplane Servicing A potential for storm water contamination is on the apron (ramp) adjacent to the passenger terminal where the airplane is serviced. The following fluids have a potential to enter the storm water system from spillage: 1-4 ------- - Engine oil - Hydraulic fluid - Lavatory fluids - Fuel - Potable water All spillage other than potable water should be prevented from entering the storm drain. Engine oil and hydraulic fluid are serviced in small containers and a large spill is unlikely. Larger spills occur when lines are replaced during maintenance activities. These spills are removed by absorbent material to prevent a discharge to the storm drainage system. Lavatory and fuel spills are usually washed into the storm drainage system by fire and safety personnel. It is necessary that spilled fuel be removed quickly from the vicinity of the airplane. Many airports are taking preventive measures to the release of spilled fluids by cleaning the ramp using vacuum trucks and by sealing cracks in the paved areas. A few airports have constructed an industrial waste interceptor to collect dry- weather flows for treatment. Airplane Deicing This includes both deicing to remove frost, snow or ice but also anti-icing to prevent the accumulation of frost, snow or ice before take off. This involves spraying the airplane with a mixture of hot water and a glycol-based fluid. The spray drains from the aircraft to the apron (ramp) and into the storm drainage system. 1-5 ------- Most airports accomplish this in the passenger terminal area but several airports are using remote sites. Runway and Ramp Deicing Runway deicing materials are normally ethylene glycol, UCAR (by Union Carbide} and pelletized urea. Liquid or solid devices are used depending on runway conditions. These deicers are usually used only after snow removal and sanding. Alternative materials including calcium magnesium acetate (CMA), are under investigation and used at several airports. RESPONSIBLE PARTIES EPA Regulation 40 CFR 122.21 covers the duty to apply for a discharge permit and 40 CFR 122.22 relates to signatures to the permit application. Airports which do not have a currently effective storm water permit must make application. The applicant is the operator of the facility. If the applicant is a public agency, the principal executive officer or ranking elected official must sign the application. Airlines and service businesses are tenants on the property and have contracts with the public agency to do business on the airport property. While a case can be made that each tenant is responsible for effluent discharges from their operations, it is the operator of the facility who is responsible for the discharge. The facility operator is required to apply for the NPDES permit and is held responsible for compliance with the permit conditions. 1-6 ------- It may be possible to identify tenants who operate specific facilities which cause discharges. For example, a tank farm may operate separately from other facilities and that tenant would be the operator responsible for a permit application. However, for the terminal facility and the runway environment, the airport authority is the operator. 1-7 ------- SECTION 2 STATEMENT OF THE PROBLEM NEED FOR DBICERS In the last 20 years, surface ice contamination was determined to be a contributing factor in at least 13 U.S. fatal airline airplane accidents. The memorable Air Florida B-737 that crashed into the Potomac River in January 1982, shortly after takeoff from Washington, DC's National Airport, sparked renewed worldwide airline interest in airplane deicing and anti-icing fluids and application procedures. The most recent tragedy involved a DC-9 that crashed at Denver's Stapleton Airport in November 1987 in moderate snow and fog. These accidents have unified efforts to standardize methods and equipment to apply ice-controlling fluids. Improper procedures or inadequate chemical applications may be life threatening mistakes in a variety of cold-temperature climatic situations. The Federal Aviation Administration, U.S. Department of Transportation, does not approve deicing fluids. It reviews a carrier's deicing procedures and training and determines if the fluids and methods being used are acceptable to the airplane manufacturer for use on their particular airplane. It promulgates regulations and develops and publishes Advisory Circulars related to deicing and ground operation safety procedures. The regulation at 14 CFR 91.209(a) states that no pilot may take off an airplane that has snow or ice adhering to the wings, or stabilizing or control surfaces or any frost adhering to the wings or stabilizing or control surfaces, unless that frost has been polished to make it smooth. The regulation at 14 CFR 121.629(b) specifies that no person may take off an airplane when frost, snow, or ice is adhering to the wings, control surfaces, or propellers of the airplane. These 2-1 ------- regulations are based on the "clean aircraft concept." Frost, ice, or snow deposits can seriously affect the aerodynamic performance and controllability of an airplane. DBICERS USED Airplanes Various devices such as brooms, brushes, ropes, squeegees, and fire hoses have been and are being used in deicing and snow removal activities associated with airplanes. Various methods of applying freezing point depressant fluids are used such as mopping of the fluid on the surface from a bucket, use of hand pumps and spreading the solution with a mop or brush, or fixed base operations where the equipment, capability, and operator experience to clean the airplane provides brief protection to allow safe takeoff to be performed. The basic philosophy of using freezing point depressant fluids for airplane deicing is to decrease the freezing point of water whether in the liquid or ice phase. All surfaces of an airplane should be coated with a solution of deicing fluids to ensure that the freezing point of remaining films will be no greater than 20°F below ambient or surface temperature, whichever is lower (Federal Aviation Administration (FAA) Advisory Circular No. 20- 117). With ethylene glycol, the most common airplane deicing chemical currently used, the minimum freeze point occurs when the freeze point depressant fluid mixture consists of approximately 60 percent glycol and 40 percent water. This is commonly referred to as the- eutectic point. Pure ethylene glycol will freeze at warmer temperatures than aqueous solutions of ethylene glycol. All currently available commercial deicing fluids contain small quantities of water. 2-2 ------- Airplane deicing generally is done with a 50/50 mix of ethylene glycol and hot water. A propylene glycol and hot water mix is used by some airlines. Alcohols receive minor use, and one airline operating out of Casper, Wyoming uses a mix of 33 percent methyl alcohol and 67 percent water for deicing. Where modern ground equipment is available, common practice is to use water heated to approximately 180°F and glycol heated to approximately 150°F. Some manufacturers recommend that hot water alone by used to melt and remove snow, frost, or ice formations from airplanes, especially at ambient temperatures above 26°F. Runways and Taxiways Only noncorrosive chemicals are acceptable for airport airside use. Common deicing agents used on runways and taxiways. include pelletized urea, ethylene glycol, mixtures of glycol and urea, potassium acetate, and CMA, which is a mixture of calcium acetate and magnesium acetate. Some airports such as at Pittsburgh, Pennsylvania; Detroit, Michigan; and Providence, Rhode Island use liquid deicers only after snow removal and sanding. Providence uses heated sand almost exclusively. In 1988-89, Logan Airport in Boston used 108,000 gallons of liquid deicer consisting of 50 percent ethylene glycol, 25 percent urea, and 25 percent water. FAA Advisory Circular No. 150/5200-30, Change 1 issued October 25, 1989, contains the warning that urea produced for agricultural use is not acceptable for airport airside use. Abrasives or friction improving materials applied to airport movement surfaces shall consist of washed granular particles free of stones, clay, debris, and chloride salts or other corrosive substances. The pH of the water solution containing the material shall be approximately neutral and certain size gradations are mandated. Sharp, hard silica sand provides the greatest increase in traction, and remains effective the longest because of its 2-3 ------- resistance to fracturing and rounding compared to softer materials, but it is also very abrasive. Limestone is softer and may be used where available if abrasion must be reduced. The application of sand at 0.1 to 0.2 pound per square foot will -i substantially increase friction coefficient. Granular particles are treated with chemicals to make them adhere to cold ice to prevent loss. At temperatures above 18°F a solution of urea is used; below this temperature glycol is effective. Approximately 8 to 10 gallons of liquid are needed to coat 1 ton of sand. Below 0°F heated sand can be more effective because of more rapid adhesion of the granules to ice (FAA Advisory Circular No. 150/5200-30). DEICER QUANTITIES USED The quantity of deicer fluid necessary to provide a clean airplane for takeoff depends upon a number of variables, including ambient temperature; airplane surface temperature; relative humidity; solar radiation; wind velocity and direction; presence of deicing fluid; type of deicing fluid and its strength; the deicing procedure used; proximity to other airplanes, equipment, and buildings; and the airplane component inclination, angle, contour, and surface roughness (Glines, 1990). Of course, the amount of snow or ice on an airplane to be deiced is a significant factor. Depending upon the weather, 60 to 120 gallons of deicing fluid may be used on a 757 airplane. If the airplane is coated with 2 inches of snow, as much as 400 gallons of deicing solution may be necessary (Lidstro'm, 1990). At the Salt Lake City airport, former usages of 175 to 600 gallons of deicing solution per airplane were reported. A change in procedure to pretreatment of an airplane with hot water reduced the glycol use. In the winter of 1989-90, 75 to 140 gallons of solution were being used on 2-4 ------- large airplanes and 50 to 60 gallons of deicing solution were being used on small airplanes. The cost of the deicing fluid is reported to be between $5 and $10 per gallon. Whitbeck (1990) in discussing deicing at Detroit Metropolitan Airport stated that depending on weather conditions, deicing requires 1,000 to 3,000 gallons of the deicing fluid for a commercial plane the size of a DC-8. At a cost of approximately $8.50 per gallon for ethylene glycol, this translates roughly to $5,000 per application for bad weather and $12,000 per application for extreme weather. When applied to aircraft, about 10 percent of the deicing fluid remains on aircraft surfaces to form a film which resists further accumulation of snow, ice, and frost. Another source (Huddleston, 1990) confirmed the high "worst case" usage of deicing fluid at Detroit Metropolitan Airport with a comment that although use of 600 to 700 gallons of Type I deicing fluid on a large airplane may be typical during severe winter weather, as much as 4,000 gallons of a 50-50 mixture of glycol water fluid has been used on a large airplane when it was coated with 1/2 inch of ice. Carter (1990) reports that up to 1,000 gallons of a 50-50 glycol and water mixture often may be used under severe weather conditions at Stapleton International Airport, Denver, Colorado. The individual airlines are responsible for the proper deicing of their own airplanes. The airport officials, without special investigation, do not know the quantities of deicing solution used for a-given p'eriod. The airlines purchase and store their products separately. However, information is available as examples that provide an indication of quantities being used. 2-5 ------- Information filed with NPDES Permit No. IL0002283 for Chicago O'Hare International Airport indicates that from July 1975 to June 1981 the average annual use of airplane deicers was 348,500 gallons. This solution was composed of 89 percent ethylene glycol, 5 percent high glycol, 0.5 percent inhibitor, and 5.5 percent deionized water. During the same time, the average annual deicer quantity applied to runways amounted to 6,800,000 pounds, which was composed of 60 percent ethylene glycol, 15 percent urea, 1 percent inhibitors, and 24 parent water. This information was contained in a petition for Variance from Effluent Standards filed by the City of Chicago on December 9, 1982. The Detroit Metropolitan, Wayne County airport used 90,000 gallons of airplane deicing solution in the winter of 1989-90; Theodore Francis Green Airport, Providence, uses 150,000 to 200,000 gallons annually; Lambert Field, St. Louis uses 50,000 to 60,000 gallons annually; Stapleton International Airport at Denver uses 700,000 gallons annually; and Sea/Tac at Seattle uses 40,000 to 60,000 gallons of airplane deicing solution annually (COM, 1990). Hartford International Airport at Windsor Locks, Connecticut, uses approximately 150,000 gallons of ethylene glycol for airplane deicing plus 20,000 gallons1of ethylene glycol with urea for runway clearance annually. Truax Field at Madison, Wisconsin used 35,000 gallons of airplane deicing fluid in 1989-90. ENVIRONMENTAL EFFECTS Environmental impacts that have been documented and attributed to deicer concentration in storm water runoff are situation dependent. Like organic wastes and wastes high in nutrients, the receiving water effects depend in large measure on the amount of dilution they afford. Ethylene glycol is toxic to aquatic life 2-6 ------- but not until substantial concentrations are present in receiving waters. Ethylene and propylene glycol both have high biochemical oxygen demands. Urea is high in nitrogen .content and with biological degradation could result in ammonia concentrations toxic to aquatic life. Receiving water environmental impacts that have been documented include fish kills, diminished dissolved oxygen, impaired benthos communities, glycol odors, algal nuisances, and glycol contaminated surface water and ground water drinking water systems. A fish kill occurred downstream from the storm water discharge at Lambert Field, St. Louis, that was linked to ethylene glycol. A characterization study will be performed in 1990-91. A domestic water supply 1 mile downstream from the Albany, New York airport was temporarily shut down when total glycol at the drinking water intake exceeded the New York drinking water standards that prohibit unspecified organic compounds in concentrations greater than 100 ug/1. Fish kills, low dissolved oxygen, and high ammonia nitrogen concentrations have occurred in the receiving water from Chicago O'Hare airport. The waste deicing fluid was discharged to a lake from Eppley Airfield in Omaha, Nebraska, which caused winter dissolved'oxygen reduction in the lake. Complaints of glycol odors from and color in the receiving stream of the Manchester, New Hampshire airport have been received. Ethylene glycol was reported to have eliminated aquatic life and impaired the operation of a sewage treatment plant in connection with storm water discharges from the Pittsburgh airport. The streams near Nashville airport in Tennessee are very small; increased biochemical oxygen demand, decreased dissolved oxygen, *. r and depressed benthos communities have been observed. A substantial portion of the airport at Anchorage, Alaska drains to Lake Hood, which is the world's largest float plane basin and a part of the 7-square-mile airport. Complaints of odors, corrosion of plane floats, and algae have been received. 2-7 ------- In February 1989, the State of Connecticut measured ethylene glycol and biochemical oxygen demand each at 400 to 500 mg/1 in runoff entering streams at the Hartford International airport at Windsor Locks. Lake O'Hare receives storm water runoff from Chicago O'Hare airport. In February 1990, the biochemical oxygen demand of Lake O'Hare's water was 1,400 to 1,800 mg/1 and the ammonia nitrogen was 90 to 110 mg/1. During eight wintertime storm water discharge events at Denver's Stapleton airport, ethylene glycol concentrations ranged from zero to 5,050 mg/1, with some later concentrations exceeding 100,000 mg/1 (COM, 1990). In early 1990, water samples from the stream receiving storm water runoff from the Madison, Wisconsin, Truax Field had a biochemical oxygen demand of 8,000 mg/1. At Cleveland's Hopkins International Airport, runoff from airplane deicing operations drains from the tarmac to storm drains. EPA Region V and Ohio EPA personnel, in February and March, 1987, found maximum concentrations of nitrate and nitrite nitrogen at 40.2 mg/1 and ammonia nitrogen at 109 mg/1 in samples collected from outfall 015, and ethylene glycol at 670 mg/1 from outfall 017. CASE HISTORIES Anchorage International Airport, Alaska: Large amounts of ethylene glycol are used on airplanes and 50/50 urea and ethylene glycol on runways. Half of the airport drains to Lake Hood, a large float plane basin. Complaints of corrosion of plane floats, odors, and algae are associated with Lake Hood. Airport authorities will hire a consultant to conduct a drainage study and prepare a feasibility study for the management of deicing fluids. Stapleton International Airport, Denver, Colorado: Airplane deicing takes place at boarding gates via boom trucks. The 2-8 ------- excess fluids and storm water drain to a detention pond where there is a controlled release to a POTW for treatment. Sand, pelletized urea, and a liquid mix of ethylene glycol and urea are used on runways. There is an NFDES permit. Continental Airlines has a centralized deicing facility. Wastewater from this facility is collected by a bypass system from the storm drain and processed off-site with a vacuum distillation tower. About 25 percent of the ethylene glycol is recovered, which is sold to off-airport clients. It is estimated that 95 percent of the wastewater from the Continental deicing facility is collected for reprocessing. Hartford International Airport, Windsor Locks, Connecticut: The airport drains to two small streams that flow through a residential area to the Farmington River, just downstream from a fish hatchery and fish ladder where attempts are being made to establish a salmon run. A consultant will collect samples in 1990-91 and develop alternative solutions for management of the deicing fluids. The existing sewage treatment plant has a capacity of only 2.5 MGD, which limits potential options. O'Hare International Airport, Chicago, Illinois: The fueling and deicing of airplanes takes place primarily in the terminal and cargo areas of the airport. Large sponges on rollers pulled with tractors, "super soppers," are used to gather up the deicing fluids, but these are not especially effective because of the congestion of traffic in the areas. The storm water runoff from the deicing areas, as well as most of the south half of the airfield, goes directly to a detention basin, Lake O'Hare, through a system of storm drains, open ditches, and an oil-water separator. The discharge from Lake O'Hare is to the Metropolitan Sanitary District sewer except when the water quality meets NPDES permit requirements or if the lake level is such that it threatens to flood O'Hare facilities. Under these conditions, 2-9 ------- water is'released from Lake O'Hare to Crystal Creek by means of a gate structure or a force main from the pumping station to Crystal Creek. Flow to the sanitary sewer is restricted to a maximum rate of 10 cfs. The amount of runoff passing through Lake O'Hare per year as measured from July 1975 to June 1981 averaged 1,250 million gallons. NPDES Permit No. IL0002283 for outfall 001 to Crystal Creek provides limits and monitoring for pH, TSS, TDS, oil and grease, BOD, ammonia nitrogen, and temperature. Louisville Airport, Kentucky: The deicing facility operated by UPS drains to two 8,000-gallon collection tanks, which discharge to the municipal sewage treatment system. Other airlines have separate deicing programs. The airport NPDES permit contains specifications for ethylene glycol of 22 mg/1 as a monthly average and 35 mg/1 as a daily maximum. Baltimore-Washington International Airport, Maryland: the NPDES permit requires monitoring for BOD, pH, ethylene glycol, and the volatile fraction of the 6C/MS scan by EPA Method 624. The permittee shall sample once every 2 weeks for the first year from December through February. Relatively mild winters have been experienced since the permit was written. Results show that, for the period January through March 1989, the BOD averaged 41 mg/1, with a maximum of 96 mg/1, and the ethylene glycol concentration averaged 41 mg/1, with a maximum of 110 mg/1. For ice control on runways in the winter of 1987-88, 800 gallons of UCAR were used with ingredients of 50-55 percent ethylene glycol, 22-27 percent urea, and 23-25 percent water. In addition, 28 tons of urea were used on runways an'd roads with ingredients of 46 percent nitrogen, 5 percent water, 0.015 percent free ammonia, and 0.8 percent burret. 2-10 ------- Logan Airport, Boston, Massachusetts: Plans are underway to assess all storm water outfalls from the airport and to study the relative effects of using ethylene glycol versus propylene glycol as a deicing fluid. An information-gathering phase of the study has been completed. Detroit Airport, Michigan: Storm water containing ethylene glycol goes to holding ponds. Liquid is held in ponds over winter and discharged at a metered rate in the spring. The biochemical oxygen demand of the ponds is monitored. Minneapolis/St. Paul International Airport, Minnesota: The airport has only 2 to 3 hours' detention time for storm water runoff, and then storm water goes directly to the Minnesota River. Lambert Field, St. Louis, Missouri: The airport was notified by the State to apply for an NPDES permit, along with Kansas City International Airport. Characterization studies will be done in the winter of 1990-91. Eppley Airfield, Omaha, Nebraska: Through an administrative order, the airport was placed on a schedule to divert storm water runoff from the lake where deicing fluids were causing a winter dissolved oxygen problem to the Missouri River where there would be no impact. Reno Airport, Nevada: The city has prohibited the discharge of deicing fluids from the airport. Following deicing operations, ' / the area is vacuumed, and wastewater is collected and taken to an oil-water separator, where it then is discharged to the sanitary sewer. The airport uses propylene glycol because they believe it to be less toxic and less quantity needs to be used. 2-11 ------- Albany County Airport, New Tork: In reviewing the literature, the New York State Department of Environmental Conservation made the determination that propylene glycol appeared to be significantly less toxic than ethylene glycol. Thus, the discharge permit for the airport was written to allow only the discharge of propylene glycol to Shaker Creek, which enters the Mohawk River - a public water supply. Salt Lake City Airport, Utah: Most airlines use a centralized deicing facility operated by Delta Airlines. Both propylene glycol and ethylene glycol are used in deicing operations. Pretreatment of an airplane with hot water has reduced the use of deicer fluids. The airport plans to capture deicing fluids where they will go to an aerated detention pond with a metered release to the sanitary sewer. 2-12 ------- REFERENCES CITED COM. 1990. Logan airport stormwater investigation final report. Camp Dresser & McKee, Cambridge, MA 021412 (May). AC 20-117. 1982. Hazards following ground deicing and ground operations in conditions conducive to aircraft icing. Advisory Circular No. 20-117. Federal Aviation Administration, U.S. Department of Transportation, Washington, DC. Carter, Miles. 1990. Personal communication. Stapleton International Airport, Denver, Colorado. FAA. 1988. Airport winter safety and operation. Advisory Circular No. 150/5200-30. Federal Aviation Administration, U.S. Department of Transportation, Washington, DC. Glines, C. V. 1990. The Icing Menace, Part II. Air Line Pilot, pp. 9-12 (January). Huddleston, Jessie. 1990. Personal communication. Page Aviation, Detroit, Michigan. Lidstrom, Bernt. 1990. Personal communication. Deicing System, Louisville, Kentucky 40220. Whitbeck, Neil. 1990. Memorandum on airplane deicers from Science and Technology Division, Legislative Service Bureau to the Honorable James A. Kosteva, State Representative (Michigan). 2-13 ------- SECTION 3 AIRSIDE DEICING AND ANTI-ICING MATERIALS AIRPLANES Airplane Deicing An airplane may be cleaned of ice formations (deiced) by any suitable manual method, by use of water, by use of freezing point depressant (FPD) fluids, or mixtures of FPD fluids and water. Heated water, FPD fluids, or aqueous solutions of FPD fluids are more effective in the deicing process. The freeze point of residual fluids (water, FPD fluids, or mixtures) should not be greater than 20°F below ambient or surface temperature, whichever is less. Unheated fluids or aqueous solutions are more effective in the anti-icing process than heated fluids (AC 20-117). Freezing Point Depressant Fluids Commercially available FPD fluids for aircraft deicing use are of the ethylene glycol or propylene glycol family. The exact formula of .various manufacturers' fluids are proprietary. Some commercially available FPD fluids contain either ethylene glycol or derivatives of ethylene glycol such as diethylene glycol with small quantities of additives and water. FPD fluids are very soluble in water. The addition of glycol to water will lower the freezing point of the water mixture (AC 20-117). The Society of Automotive Engineers (SAE) through Aerospace Material Specifications (AMS) and the military (MIL) provide specifications for airside chemicals. These specifications are for chemicals applied to aircraft and chemicals and sand applied to runways and taxiways. SAE AMS 1425A and SAE AMS 1427 are for ethylene glycol base and propylene glycol base aircraft 3-1 ------- deicing/anti-icing fluids, respectively. They provide technical requirements of the concentrated liquids including flash point; specific gravity; pH; pour point; viscosity; several tests for corrosion; effects on transparent plastics, painted surfaces, and •i unpainted surfaces; performance; and quality. Both of these standards were issued in 1981. Ethylene Glycol The Air Transport Association in a March 1989 letter writes, "Ethylene glycol is the dominant deicer in use by airlines in the U.S. today. It is not strongly offensive to the environment but does create excessive biological oxygen demand in some discharges. 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. Propylene glycol is less toxic than ethylene glycol, but has a higher biological oxygen demand. The propylene compound being a long-polymer formulation, would be more difficult to recycle because the necessary handling breaks up the polymer." (ATI, 1989). The U.S. Environmental Protection Agency has issued a health advisory for ethylene glycol (EPA, 1987). The 1-day health advisory for a 10 kg child exposed to ethylene glycol in drinking water was calculated to be 18.86 mg/1. The longer-term or approximately 7-year health advisory for a 10 kg child was calculated to be 5.5 mg/1 and for a 70 kg adult to be 19.25 mg/1. The lifetime health advisory is 7 mg/1 in drinking water with 70 kg as the assumed body weight of an adult and 2 liters per day as the assumed daily.,water consumption. The health advisory cited a controlled study of human exposure to ethylene glycol by Reif (1950) in which the investigator drank 5.5, 11.0, and 13.2 grains of ethylene glycol with 100 ml of water on separate occasions and collected his urine for about 14 days after each trial to quantify ethylene glycol and oxalic acid levels. Assuming a body 3-2 ------- weight of 70 kg, doses consumed would be 78.5, 157.0, and 188.6 mg/kg. Reif found that 24 to 31 percent of the ethylene glycol was excreted in the urine in an unchanged form within 24 to 36 hours. The approximate human single oral lethal dose has been recorded as-1.4 ml/kg, which is equivalent to ingesting about 3.3 fluid ounces of ethylene glycol for the average sized individual (Clayton and Clayton, 1982). For a rat, the lethal dose has been recorded at 5.89 g/kg (COM, 1990). Ethylene glycol is an animal teratogen but is negative for mutagenicity and carcinogenicity. Sills (1990) reviewed seven pieces of literature on the aquatic toxicity of ethylene glycol. These data indicate that the 96- hour LC50 for the fathead minnow ranged from 10,000 mg/1 to 57,000 mg/1 in four tests, for the rainbow trout the range was from 16,000 mg/1 to 41,000 mg/1 in three tests, and for the bluegill the range was 40,000 mg/1 to greater than 100,000 mg/1 in two tests. The 48-hour LC50 for Ceriodaphnia dubia/affinis in two tests was 10,500 and 22,600 mg/1, and for Daphnia magna the range was 10,000 mg/1 to 51,000 mg/1 in six tests. From these data, Sills calculated draft water quality criteria with acute value of 3.08 g/1 and aquatic chronic value of 68.5 mg/1 for ethylene glycol. In an aqueous environment, ethylene glycol, which contains carbon, hydrogen, and oxygen, ultimately will be decomposed into carbon dioxide and water. Small amounts of mineral supplements are required for this activity. Phosphate, for example, plays an important role in the metabolism of any organism, with the resultant release of energy; the phosphate acts as a catalyst so only a trace is required. A nitrogen supplement such as an ammonium salt also is required. The amount of oxygen used in the oxidation of organic matter by aerobic bacteria is the biochemical oxygen demand (BOD). The amount of oxygen required to completely oxidize an organic material to carbon dioxide.and 3-3 ------- water is known as the chemical oxygen demand (COD). BOD is considered to be the quantity of oxygen required for biological stabilization of water-borne substances under a specific set of test conditions (UC, 1984). The measured 5-day BOD of ethylene glycol is 0.465 mg 02/mg of ethylene glycol. This is 36 percent of the theoretical oxygen demand of 1.29 mg 02/mg ethylene glycol. Similarly, the- measured 20-day BOD is 1.39 mg 02/mg ethylene glycol which is 100 percent of the theoretical oxygen demand. Because ethylene glycol is rapidly biodegradable, large quantities could represent a significant oxygen demand in receiving waters (UC, 1984). As noted under Section 2, "Environmental Effects," of this document, a BOD as high as 8,000 mg/1 has been measured in receiving waters from airplane deicing operations. This BOD may be compared to raw sewage with a corresponding BOD of 300 mg/1. Propylene Glycol Propylene glycol appears to be less toxic than ethylene glycol. The LD50 to the rat is 21 grams per kilogram of body weight. Propylene glycol was first used in foods in the United States during 1920. It was recertified in 1978 as "Generally Regarded as Safe" when used in food as an emulsifying agent, and general purpose food additive, as well as in paper and paperboard products used in food packaging. Undiluted propylene glycol was tested on 1S56 persons in a 24-hour patch test; 12.5 percent of those tested had reactions. Seventy percent of the reactions were of a toxic type and 30 percent were allergic in nature. Reactions'to propylene glycol were seasonal, ranging from 17.8 percent in the winter to 9.2 percent in other seasons. The inhalation of substantially saturated atmospheres of propylene glycol presents no health hazards. Aerosols and fogs of propylene glycol have not been well-studied. Propylene glycol 3-4 ------- does not appear to be carcinogenic or teratogenic and does not affect, maternal or embryo toxicity in several test species (WEEL, 1984). A lethal dose for humans of 15 g/kg or about 35 fluid ounces for the average sized person has been reported but the original source of the information has not be verified (COM, 1990). The 96-hour LC50 for fish has been reported at 54,760 mg/1 (UC, 1984). The theoretical oxygen demand has been listed as 1.685 g/02/g or propylene glycol. This compares to 1.26 g/02/g for ethylene glycol on the same basis by the same author (COM, 1990). Type I and Type II Fluids 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. Type I fluids are usually water and ethylene glycol and/or propylene glycol mixtures with a minimum glycol content of 80 percent. They are diluted 1:1 with water prior to application. Type 1 fluids have been in worldwide use for many years to remove ice, snow, and frost. They offer limited protection against re-icing during continued precipitation (Foshee, 1990). Type II fluids have a glycol content of at least 50 percent and a thickener system composed of polymers that forms a pseudoplastic film that protects the aircraft from rapid re-icing and increases its holdover time. During takeoff, the shearing force of the airstream causes the fluid viscosity to rapidly decrease at speeds above (30) knots. The thinning fluid flows off the wing and tail surfaces. This tends to deposit on the runway at the takeoff location and cause some slickening on the runway (Foshee, 1990). A fluid applied for anti-icing of an aircraft should be 3-5 ------- applied within three minutes of the start of the deicing' operation. Under very bad weather conditions of freezing rain with the outside temperature at 0°C (32°F) and above the Type I fluid may protect an aircraft for 5 minutes. Under similar conditions, the Type II fluids, if applied full strength, would be expected to protect the aircraft for 20 minutes. Under conditions of frost only, the relative aircraft protection would be 45 minutes for the Type I fluid and several hours for. the Type II fluid (ATA, 1990). RUNWAYS AND TAZIWATS Runway Deicing Deicing chemicals should be applied on ice 1/16 inch or less in thickness. Thicker layers of ice require an extended period of time to obtain ice-free pavement. However, solar radiation from even a cloudy sky enhances melting action to such an extent that elimination of ice thicknesses greater than 1/16 inch is possible. The recommended chemical form-for anti-icing is liquid, which includes solid chemicals in solution. A dry chemical applied to a cold dry surface may not adhere and may be blown off or scattered by either surface winds or aircraft movements. Wetting a dry anti-icing chemical, either during distribution or before or after loading into the application vehicle, improves the ability to achieve uniform distribution and improved adhesion (AC 150/5200-30 CHG 1). Chemicals Used Airside chemicals approved for non-airplane applications are urea, ethylene glycol, calcium magnesium acetate (CMA), and 3-6 ------- magnesium calcium acetate (MCA). The Society of Automotive Engineers (SAE) through Aerospace Material Specifications (AMS) and the military (MIL) provide specifications for airside chemicals and sand (AC 150/5200-30 CH6 1). Urea The applicable specifications for urea, also called carbamide, are SAE AMS 1730A, Urea Compound-Shotted, SAE AMS 1731A, Urea Compound-Powder, and MIL SPEC DOD-U-10866D, Urea-Technical. Urea produced for agricultural use is not acceptable for airside use (AC 150/5200-30 CH6 1). Powdered urea frequently is mixed with sand. Hot mixtures of powder or shotted urea and sand serve two purposes: (1) immediate increase in braking action and (2) retention of chemical over the pavement area until it initially dissolves some of the ice and then melts the remainder. The urea deicing function is practical only at temperatures above approximately -9.4°C (15°F) because of the decreasing melting rates below this temperature. Urea's eutectic temperature is approximately 11.3°F. However, the presence of solar radiation assists urea in the melting action. Pavement surface temperature and ice thickness determine the urea application rate. Application rates may vary between 0.16 pounds per square foot at a temperature of 30°F (-1.1°C) and an ice thickness of less than 1/32 inch to 0.275 pound per square foot at a temperature of 21°F (-6.1°C) and an ice thickness of 1/8 to 1/4 inch. Urea in water degrades to carbon dioxide and ammonia. The ammonia formed can either remain in solution as NH3 and NH« species, convert biologically to other forms of nitrogen such as N03 or N2, or volatilize into the air. The theoretical oxygen demand for the biodegradation of urea to the end products of carbon dioxide and ammonia is 0.27 mg of oxygen per mg of urea. If the ammonia further decomposed to nitrate the theoretical 3-7 ------- oxygen demand increased to 1.87 mg 02/mg of urea. Urea may degrade in river water in four to six days at 20°C (68°F); at temperatures less than 8°C (96.4°F), negligible degradation occurs (Chev.r 1990). Unionized ammonia (NH3) can be toxic to aquatic life at very low concentrations depending upon the temperature and pH of the receiving water. To prevent toxicity, for example, if the runoff temperature is 0°C (32°F) with a pH of 7.5, the maximum allowable urea content is 30 ppm. Typical urea concentrations in runoff can exceed 1,000 ppm (Chev., 1990). Also, urea supplies abundant nitrogen to the receiving water, which may lead to algal blooms and nuisances along with the environmental problems that these produce. Bthylene Glycol Ethylene glycol was under Section 3 of this document. The use for airport runways is under different SAE MAS specifications than the use for aircraft application; the specifications are less restrictive for runway use. Application rates of glycol- based liquids range from one to two gallons per 1,000 square feet of surface to be covered for deicing, and 0.2 to 0.5 gallon per 1,000 square feet for anti-icing. Calcium Magnesium Acetate Product (CMA/MCA) Interim specifications for CMA/MCA are in Appendix 4 of AC 150/5200-30 CH6 1. Various investigations referenced by Chevron indicate that CMA'vill have very little negative impact on the environment when used for deicing (Chev., 1990a). Toxicological studies have shown that CMA is at least as safe as common table salt. It is not phytotoxic to herbaceous or woody plants. It is readily absorbed and degraded in soil and will not reach ground 3-8 ------- water. The acute LD50 of CMA for rainbow trout and fathead minnow has been recorded at 18,700 and 21,000 mg/1, respectively. Animal tests indicated no toxicity at an oral dose of 1,000 milligrams CMA per kilogram of body weight per day. The acute oral LD50 was approximately 3,150 milligrams per kilogram of body weight. The 5-day biochemical oxygen demand is 0.54 grams of oxygen per gram of CMA. Investigations into the effects of CMA on the activated sludge process concluded that CMA shows no detrimental effects on sewage treatment. This material currently is under investigation for use in non- airside highway bridge treatment. The monetary cost of such use is about 18 times the cost of road salt. The savings expressed in reduced vehicular corrosion may equalize the relative costs of applying the two chemicals. In addition, the environmental costs of using CMA would be substantially less than those associated with the use of road salt. Chemicals Under Investigation 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. Presently, this product cannot be used because SAE AMS specifications have not been developed and approved. If potassium acetate were to be used for airside purposed, the expected environmental impact of its use would be low. 3-9 ------- REFERENCES CITED AC 20-117. 1982 (Re-distributed 1988). Hazards following ground deicing and ground operations in conditions conducive to aircraft icing. U.S. Department of Transportation, Federal Aviation Administration, Washington, DC. AC 150/5200-30 CHG 1. 1989. Advisory Circular 150/5200-30 with pages revised 10/25/89 by Change 1. U.S. Department of Transportation, Federal Aviation Administration, Washington, DC. AC 150/5320-XX Draft. 1990. Management of airport industrial waste, Advisory Circular,'Draft. U.S. Department of Transportation, Federal Aviation Administration, Washington, DC. ATA. 1989. Letter from Clyde R. Kizer, Air Transport Association of America, Washington, DC, to Tom Seaton, U.S. Environmental Protection Agency, dated March 17, 1989. ATA. 1990. Aircraft de-icing/anti-icing methods with fluids (5th draft, 4.90) Air Transport Association of America, Washington, DC. CDM. 1990. Memorandum to Roberta F. Ellis, Chief of Environmental Management, Massport from Bryon Clemence and Brent McCarthy, Camp Dresser & McKee, Comparison of ethylene and propylene glycol, January 5, 1990. Chev. 1990. Chevron ICE-B-60N runway deicer, urea's fate in the aquatic environment, Chevron Chemical Company, San Ramon, CA. Chev. 1990a. Chevron ICE-B-GON runway deicer, environmental impact, Chevron Chemical Company, San Ramon, CA. Clayton, G. G. and F. E. Clayton. 1982. Patty's Industrial Hygiene and Toxicology, Third Revised Edition, VOL. 2C P. 3821. . EPA. 1987. Ethylene glycol health advisory. Office of Drinking Water, U.S. Environmental Protection Agency, Washington, DC. / Foshee, William C. 1990. Dow Chemical Company, Midland Michigan, Flightgard 2000 brochure. Reif, G. 1950. Self-experiments with ethylene glycol. Pharmazie, 5:276-278. Sills, Robert. 1990. Michigan Department of Natural Resources, Personal Communication. 3-10 ------- UC. 1984. Ecological aspects of UCAR aircraft deicing fluids and ethylene glycol for Hazardous Materials Technical Center, Rockville, MO. Union Carbide Corporation, South Charleston, W.VA. WEEL. 1984. Workplace environmental exposure level (WEEL) for propylene glycol, prepared by Scott D. Herzog, October 1, 1984, copy supplied by Dennis Dobyns, City of Reno, NV. 3-11 ------- SECTION 4 CONTROL OPTIONS FUTURE TRENDS In a questionnaire survey of U.S. airlines conducted by the Air Transport Association of America, there was an expressed belief that trends are toward use of Type II fluids in deicing;. expansion of end-of-runway deicing; and deicing fluids collection and discharge to holding tank or detention basin with controlled flow to a municipal treatment system where-possible. The opinion was expressed by some that centralized deicing may be 5 years away at best (ATA, 1990). In this same survey, the airlines were asked to describe the desired features of a central or remote deicing facility. Those features included: a. Drive-through gantry operation in taxiway vicinity enroute to departure b. Deicing fluid retention and recycling c. Capability of deicing several aircraft at one time rapidly d. Fully computerized deicing system with automatic adjustment for different aircraft types The fear was expressed by several respondents that it would be difficult to control the quality of reclaimed deicing fluids (ATA, 1990). 4-1 ------- MANAGEMENT PRACTICES During efforts to reduce the glycol contamination of storm water at Stapleton International Airport, the advantages and disadvantages of alternative management practices were considered (COM, 1987). These alternative management practices were grouped into three broad topics that are discussed below. Under the topic of changing operations at existing deicing locations, the substitution of propylene glycol for ethylene glycol was considered. The health risk to humans would be somewhat reduced by this action but disadvantages include a higher oxygen demand in wastewaters, increased costs, and the creation of slippery conditions on the ground. The reduction in the quantity of deicers through use of hot water deicing was considered. This should reduce the amount of ethylene glycol used, although the remaining ethylene glycol would be sufficient to cause significant environmental concern. This would require operator retraining and probably equipment changes. This concept has been implemented at the Salt Lake City airport as discussed in Section 2 of this document. The collection of waste glycol on the ramp by scrubbers, absorbents or super soppers was considered. These are labor intensive operations with material and equipment costs that tend to disrupt ramp operations. The operation is difficult under bad weather conditions in a highly congested traffic area. The elimination of contamination is uncertain. A centralized facility for deicing with operation by one entity would provide better control over deicing operations. The airlines are apparently concerned about time delays and deicing procedures associated with a centralized facility. 4-2 ------- Another management practice involved collecting all or part of runoff to include the aircraft deicing operation. TREATMENT AND DISPOSAL The treatment and disposal of glycol wastes was considered by the FAA in AC 150-5320-XX (1990). Much of the following information was taken from that Advisory Circular. The location of deicing and anti-icing operations generally prescribe the method or applicable alternative methods for managing glycol waste. The most common location for deicing/anti-icing at U.S. airports is along the apron areas where specially designed, mobile deicing vehicles operate from gate to gate. A few airports operate away from the gate areas at centralized locations where a stationary dispensing system may be used. Disposal to Sanitary Sewage Facility Because glycols are readily biodegradable, their runoff could feasibly be treated with sanitary sewage. A treatment plant would have to have the capacity to handle the hydraulic load and the additional biochemical oxygen demand associated with the glycols. Measurements have shown that the average oxygen demand for glycols is between 400,000 and 600,000 mg 02/1 even if diluted per fluid manufacturer's specifications (AC 150/5320-XX). To lessen the load effects of glycols on treatment plants, on- site retention ponds may be used not only to better control the rate of flow during peak flight hours but also to stabilize the waste. Treatment in a Biological Oxidation Facility An on-site biological oxidation facility using extended aeration, contact stabilization, or trickling filters would not be 4-3 ------- practical for only glycol-based deicing fluids because of the seasonal nature of their usage. In addition, glycols cannot provide nutrients, such as nitrogen and phosphorus, for microbial growth other than an organic carbon source. Nutrient addition can be achieved by channelling sanitary sewage from airplane lavatory cleaning and airport restroom facilities to the treatment system. Lagoons, Detention, and Retention Ponds Conversion of suitable unused airport land into lagoons, detention, or retention ponds allows collection of large volumes of glycol waste from pavement surface runoff. The design capacity for such basins should at least handle surface runoffs for winter months noting the decreased microbial activity needed for biodegradation during the winter season, plus additional capacity for the thawing periods. Continuous aeration would supply required oxygen and allow for faster biodegradation and release of glycol waste, which may reduce capacity requirements. Birds and airports are incompatible. The configuration of any retention basin should be easily defensible from a wildlife standpoint. Square or circular retention basins should be avoided as they provide an attraction to birds. Waterfowl will seek the safety of a pond's center to escape harassment activities. The retention basin should be linear in configuration thereby facilitating wildlife harassment or covering, if necessary. As glycol has an attractive sweet taste but is toxic to wildlife, covering may be necessary to prohibit any wildlife use.., Fencing should be a consideration whenever potentially hazardous compounds are stored in open areas. 4-4 ------- Land Disposal Where glycol use is small, runoff glycol wastes can be collected with absorbent material and/ where permissible, disposed of in a landfill. However, since glycols are readily biodegradable, this method of disposal would be highly inefficient because of absorbent material and transportation costs. An alternative to this would be land treatment, if permitted, in which the waste is applied to the soil to allow native microorganisms the opportunity to degrade the glycols. At some locations, some runway and apron waste glycol fluids are discharged directly to the soil. This type of disposal can become a concern as ground water supplies may be affected. In addition frozen ground may not readily absorb viscous wastes. Recycling Methods of physical separation might be applied in order to recover a relatively reusable glycol product. In this case, the primary sewer discharge would be water with very little glycol waste. Recycling provides the airport operator a chemical cost savings since the recaptured glycol could be sold or reused for other non-airside applications (AC 150-5320-XX). The unresolved issue related to use of recycled solution on aircraft is the quality of the fluid to be used. There is concern related to flash point and corrosivity, and the testing required to demonstrate that fluid applied to an aircraft meets SAE AMS specifications. Some required fluid tests take seven days to complete. In discussing this matter with airport personnel in Paris, France, and Oslo, Norway, where glycol recycling takes place, it is apparent that the recycled glycol is used to deice aircraft 4-5 ------- after it is blended with unused fluid. Testing of the fluid, prior to aircraft application, however, is an infrequent event. Recycling of glycol is planned for the new airport in Munich, Germany. The airport and centralized deicing facility is scheduled to be in operation in 1993. Reduction in Chemical Usage Computerized spraying systems for aircraft deicing/anti-icing operations are in use today. The basic system consists of a dedicated pad for the deicing operation, equipment with computerized spray nozzles, a recovery system for spilled waste, and other support items unique to the system. Because it is more efficient, this type of system reduces the quantities of glycol- based fluids applied to aircraft surfaces and thereby minimizes the waste management task. CANADIAN EXPERIENCE Eedy and Salenicks (1990) evaluated six glycol-based deicer runoff alternatives for eight Canadian international airports. Their report considered the following: Alternative 1: Centralized deicing pad with glycol recovery and recycling. This included a drainage collection pad with filtration and distillation facilities to recover the glycol. This could either be operated with or without an automatic deicing gantry - sort of airplane car wash to replace manual spraying. This facility can save money and prevent pollution through glycol recovery. It does not require a large space for storage or treatment of volumes of runoff. At the same time it has not been a widely proven technology and there were debates 4-6 ------- over its ability to process large volumes of airplanes without delays. It also has relatively large capital costs. Alternative 2s Collection and treatment at municipal sewage treatment plant. If collection and treatment facilities are available at a reasonable cost/ this could provide a proven technology at minimal cost and requiring minimal space. Transportation could be by truck or by pipe, if distances were minor or sewer capacity available. Seasonal high BOD3 loading could upset a sewage plant. Some pretreatment and storage might thus be necessary. Municipalities might find it difficult to make long term commitments to such large treatment volumes that might limit their own capacity to meet effluent regulations or allow expansions to accommodate other users. Alternative 3s Treatment with on-site aeration lagoon. This is a proven technology well suited to BOD5removal at a reasonably low cost. A large land area is required and lagoons can attract birds. If inadequately aerated, odors can result. \ Alternative 4s On-site treatment with rotating biological contactor. Pilot tests have indicated .this alternative works well with glycol and it has the lowest capital costs with one exception. Costs could escalate if a building has to be erected to house the RBC facility. RBC does not work well with high fluctuations in flow or concentration. It was thus felt that an equalizing storage facility would be required to maintain equivalent flows throughout the year. This would cause potential space, odor and bird attraction problems similar to a lagoon. / Alternative 5s On-site treatment using wet air oxidation. This facility would require little space and have no storage lagoon. It could also be used to treat airline solid wastes as well. It was the most costly alternative. It also requires a centralized 4-7 ------- deicing or storage facility. Post oxidation biological treatment might be required. This is unproven technology. Alternatives not Considered Feasible! The no action alternative was not considered feasible as all of the airports studied exceed federal water quality guidelines significantly. Alternative to glycol use, such as warm water or other antifreezes were not considered feasible since airport managers felt they were unproven and could result in safety risks. Vacuum sweeping to collect runoff for treatment has been tested at several airports and has proven unsatisfactory. Other alternative were given preliminary evaluation but not recommended because of unproven technical feasibility with glycol or preliminary nature of such tests. These included on-site high-rate aerobic treatment such as extended aeration, contact stabilization, trickle filters, peat, activated carbon, an aerobic digestion, reverse osmosis/ultrafiltration, and ultraviolet oxidation. 4-8 ------- REFERENCES CITED AC 150/5320-XX Draft. 1990. Management of airport industrial waste, Advisory Circular, Draft. U.S. Department of Transportation, Federal Aviation Administration, Washington, DC. ATA. 1990. Questionnaire survey of airlines, preliminary information. Air Transport Association of America, Washington, DC. CDM. 1987. Control of Industrial waste and ethylene glycol contamination of stormwater at Stapleton International Airport. Camp Dresser & McKee, Cambridge, MA 021412. Eedy, Wilson and Sandra Salenicks. 1990. Environmental impacts and control of glycol-based deicer runoff at eight Canadian international airports. Beak Consultants Limited, 14 Abacus Road, Brampton, Ontario L6T 5B7. 4-9 ------- SECTION 5 NPDES PERMIT Section 402(a) of the CWA provides for the issuance of a permit for the discharge of any pollutant, after the opportunity for a public hearing. The permit must comply with national effluent standards and water quality standards. In the absence of national effluent standards, the permit will be issued based on the best professional judgment of the issuing authority. The U.S. EPA has delegated permit issuance authority to most States. These States operate the permit program under their State laws. The Federal program and most State programs are called the National Pollutant Discharge Elimination System (NPDES). NPDES permits are issued after the discharger has made application, and are for a fixed term not exceeding 5 years. Many airports have NPDES permits for discharges of wastewater and/or storm water. In 1987, the Congress amended Section 402 to phase-in storm water permittees. Section 402(p) provides that a permit shall not be issued prior to October 1, 1991 for discharges composed entirely of storm water except for municipalities of a specific population, discharges associated with industrial activity, and discharges that contribute to the violation of a water quality standard or are a significant contributor of pollutants to the waters of the United States. The storm water regulations were proposed in the Federal Register on December 7, 1988, and have listed transportation facilities as having storm water discharges associated with industrial activities. These'transportation facilities are under SIC 40 through 45 and 47, which have vehicle maintenance shops (including vehicle rehabilitation, mechanical repairs, painting, fueling, and lubrication), material handling facilities, equipment cleaning operations, or airport deicing operations. 5-1 ------- Most airports are included by this definition, but only those portions of the airport involved in these operations are subject to a storm water permit. PERMIT APPLICATION Applications for a permit were required to have been filed by February 4, 1990, three years after the amendment to Section 402 of the CWA. The law further requires the EPA Administrator or the State to issue or deny each permit by February 4, 1991. However, EPA is not expected to establish regulations setting forth the permit application requirements until November 1990. These regulations will have specific application requirements. The regulations will provide for both individual or group applications. Individual applications must be filed within 12 months of the effective date of the regulations, and Part 1 of the group application must be filed within 120 days of the effective date of the regulations. An individual application must be filed by the airport operator. Applicants for discharges composed entirely of storm water must' submit Form 1 and Form 2F. If non-storm water is also discharged, the applicant must also submit Form 2C. The following information is required with the application: Site map Estimate of the impervious area Certification of absence of non-storm water discharges History of spills Data on storm events A group application may be filed by an entity representing a group of applicants, such as a trade association. A general permit may be issued when the group operations and discharges are 5-2 ------- sufficiently similar to be appropriate for a general permit. Part 1 of a group applicant must include the following: Identification of participants Description of industrial activities List of significant materials stored outside and materials management practices Identification of dischargers to participate in Part 2 For participants, information required for individual applicants Part 2 will include quantitative data from selected dischargers. This is the same information as is required under NPDES Form 2F for individual airport applicants. The Part 2 participants must be representative of the group, and may be 10 percent of the^k ^T group with at least one discharger from each precipitation zone. AT least ten airports must provide quantitative data. PERMIT ISSUANCE The NPDES application is a public document. Applicants for an NPDES permit and other interested parties have the opportunity to participate in a public hearing and to provide comments to the issuing authority. Permit writers may request additional information and consider -all information brought to their attention. Therefore, permit writers are encouraged to require an airport storm water management plan to be submitted as part of the application. Permitting priorities are established by the issuing authority, either the EPA or the State. The potential impact of the discharge to the water body may be dependent upon the location of the discharge relative to the water body, the magnitude of the discharge, and the industrial pollutants in the discharge. For 5-3 ------- example, airports adjacent to public drinking water supplies or impaired water bodies should have a high priority for permitting. Also, general aviation, reliever, air taxi, and military airports which have more than 100,000 operations a year or air carrier airports with runways over 5,000 feet should have a high priority. Airport operations which have a history of spills and those with extensive deicing operations should have a high priority. PERMIT CONDITIONS The permit issued to an airport may include effluent limitations, monitoring requirements, standard and special conditions, and a schedule of compliance. The special conditions may include a plan to control the discharge of pollutants. Effluent limitations for discharges composed entirely of storm water may be unnecessary except during winter operations, when frost and snow result in the use of deicing fluids on airplanes and runways. These fluids, containing glycols, frequently result in a discharge that consumes large amounts of oxygen in the receiving body of water. The permit writer may then include effluent limitations on BOD3, TSS, pH, oil and grease, and other pollutants based on a review of additional information. A water quality assessment may be necessary. Water quality assessments may result in effluent limitations on glycols and nitrogen. When treatment of glycols is necessary, a permit writer may consider the level of effluent quality attainable through the application of secondary treatment (40 CFR 133). A BOD5 and TSS of 30 mg/1 for the monthly average and 45 mg/1 for the maximum level would be essentially consistent with secondary treatment 5-4 ------- information. These limitations would be appropriate only if sanitary wastewater and storm water receive secondary treatment. Monitoring requirements will be dependent upon the type of storm water controls the airport intends to use. The minimum requirement is annual sampling and analysis for each discharge point. Monthly monitoring is necessary when the potential for a toxic discharge exists, when there is a history of improper discharges, or when water quality is an important consideration. The discharger must sample the effluent when deicing fluids are being discharged so that the sample is representative of the discharge. As part of the application process, an airport should be required to develop a storm water management plan to control storm water discharge. A storm water management plan must address the conditions at the airport that it is designed to serve. It should consider all options for control of storm water discharges, including non-structural controls that prevent the discharge of pollutants. STORM WATER MANAGEMENT (SWM) PLAN This section applies to discharges contaminated with deicing fluids. It may be difficult for the permit.writer to establish numerical effluent limitations, because storm water contaminated with deicing fluid is seasonal and subject to a variety of control options. Where numerical effluent limitations are impractical, the permit writer should require the airport applicant to submit a storm water management (SWM) plan as part of the application. The SWM plan should be a document prepared by the airport authority in cooperation with all interested tenants and airport 5-5 ------- contractors. It is different from the other application> information in that it reviews all possible control options and selects those to be implemented during the period the NPDES permit is in effect. A schedule for implementation of each option must be included. The SWM plan is not applicable to group permits because it is site specific. This may limit group permits to those airports without a need to consider controls on used deicing fluids. The SWM plan will be reviewed by the permit writer and will be subject to public review and comment. A satisfactory SWM plan will be incorporated as part of the NPDES permit and will be subject to compliance requirements. The applicant should be asked to develop and submit the SWM plan with the NPDES application. If necessary, it can be requested under Section 308 of the CWA. Applicants should be clearly instructed to consider each element of the following SWM guidance and to document the conclusion and rationale for each element. The SWM plan should be designed to prevent or minimize the potential for release of deicing agents to the waters of the United States through airport site runoff, spillage or leaks, waste disposal, or drainage from raw material storage. In all cases, the applicant must consider the FAA Advisory Circular (AC 150/5320-XX - Draft), Management of Airport Industrial Waste. Chapter 9, Management of De/anti-icing. Chemical Waste will be necessary to develop this plan. The SWM plan should include the required information in I below, and should consider each of the additional elements, and document the conclusion and rationale for each element. Additional control options may be considered. 5-6 ------- I. Required Information a) Maps - Document with any necessary plot plans, drawings, or maps identifying all deicing areas and points of discharge. Other documents already prepared for the facility such as a safety manual or a Spill Prevention, Control and Countermeasure (SPCC) plan may be used as part of the plan and may be incorporated by reference. b) Evaluation - A review of all facility components, systems, or operations (including material storage areas; in-plant transfer, process, and material handling areas; loading and unloading operations; snow removal operations; and waste storage/disposal areas) where deicing agents are used, stored, or handled to evaluate the potential for the. release of pollutants to the waters of the United States. In performing such evaluation, the permittee shall consider such factors as the possibility of equipment failure or improper operation, the effects of natural phenomena such as freezing temperatures and precipitation, and the facility's history of spills and leaks. c) Current Controls - Identify measures or controls that have been established to minimize the potential for a release of deicing agents to U.S. waters. II. Treatment and Control / d) Non-structural Controls - Consider typical industry practices such as spill reporting procedures, risk identification and assessment, employee training, 5-7 ------- inspections and records, preventive maintenance, good housekeeping, materials compatibility, and security. e) Structural Controls - Consider structural controls, such as secondary containment devices, where they are appropriate to prevent improper discharge. £) Central Collection - Evaluate the advantages and disadvantages of a spent deicing. fluid central collection and disposal system. Consideration should be given to one or more centralized collection areas to include: Capital and annual maintenance cost Treatment and disposal cost Monitoring cost compared to monitoring existing discharge Labor cost savings Increase or reduction in take-off delays after deicing Deicing efficiency and safety Reduction of glycol usage g) Deicing Application - Consider modification of procedures and equipment to reduce pollution. h) Alternative Materials - Use of alternative deicers with reduced environmental impact. Consider airplane deicers/anti-deicers and runway deicing. \ i) Storage - Accumulation of spent deicers for disposal when discharge quality would not violate water quality standards. 5-8 ------- j) Treatment - Consider biological, physical, and chemical treatment, and incineration. k) POTW - Consider the oxygen demand on the municipal treatment facility and the need for pretreatment. 1) Recycle - Consider recycle of deicing fluid. m) Lagoons - Use of lagoons, detention, and retention with or without aeration. PROHIBITIONS The following prohibitions should be included in the permit to prevent elicit discharges. a) No industrial process wastewater discharges are permitted to be discharged into or through a storm water system, including wastewater from the following operations: Airplane maintenance Airplane cleaning Vehicle maintenance Vehicle washing Fire training b) Spills resulting from servicing the airplane, including engine oil, hydraulic fluid, lavatory fluids, and fueling, are prohibited from discharge through the storm water system. 5-9 ------- c) Tank bottoms from gasoline, aviation fuel, oil, or deicing storage tanks are prohibited from discharge through the storm water system. 5-10 ------- |