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
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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.
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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.
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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
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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
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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
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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
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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
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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
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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.
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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:
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- 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.
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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.
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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.
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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
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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.
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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
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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
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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
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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.
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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
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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,
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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.
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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
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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,
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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.
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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,
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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.
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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.
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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).
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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
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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
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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
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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
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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
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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
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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
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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
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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.
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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.
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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.
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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).
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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.
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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
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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.
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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
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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
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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
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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.
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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.
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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.
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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
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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
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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
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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
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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.
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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,
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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.
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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.
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c) Tank bottoms from gasoline, aviation fuel, oil, or deicing
storage tanks are prohibited from discharge through the
storm water system.
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