v>EPA
                        United States
                        Environmental Protection
                        Agency
                       Office of Water
                       Washington, D.C.
EPA832-F-99-016
September 1999
Storm Water
Management Fact Sheet
Minimizing Effects  from  Highway  Deicing
DESCRIPTION

The United States is critically dependent on its road
system to support the rapid, reliable movement of
people, goods, and services. Even in the face of
winter storms, we expect roads and highways to be
maintained to provide  safe travel  conditions.  In
many  states, this requires substantial planning,
training,  manpower,  equipment,  and  material
resources to clear roads and streets throughout the
winter.

The dependency on deicing chemicals has increased
since  the  1940s  and  1950s to  provide "bare
pavement"   for  safe  and  efficient  winter
transportation.  Sodium chloride (common table
salt) is one of the most commonly used deicing
chemicals.  Concern about the effects of sodium
chloride on the nation's  environment and water
quality has  increased with this chemical's usage.
Automobile and highway bridge deck corrosion has
also become a concern. However, in most cases
sodium chloride is the  most cost effective deicing
chemical. Such concerns have led to maj or research
efforts by the Strategic Highway Research Program
(SHRP),  the  highway   community,  industry,
government, and academia. This ongoing research
is exploring many  different areas  in an effort to
maintain  the safest roads  possible in the most
economical way while protecting the environment.

This fact sheet summarizes research addressing
water pollution and associated effects from deicing
chemicals, and  describes the methods used to
control snow and ice on roadways while minimizing
impacts on the environment. Because of this topic's
breadth,  sources  for  research  and  alternative
methods are listed and  can be referenced for more
detail. This fact sheet emphasizes methods and
practices for snow removal that are feasible and cost
                      effective for local governments to implement and
                      that are also consistent with sound environmental
                      quality goals.

                      APPLICABILITY

                      Beginning in the late 1940s and 1950s, the "bare
                      pavement" policy was gradually adopted by highway
                      agencies as the standard for pavement condition
                      during inclement weather.  The policy provided
                      safer travel conditions on roadways and became a
                      useful concept for roadway maintenance because it
                      was a simple and self-evident guideline for highway
                      crews. Dispersion of city populations into suburbs,
                      higher travel speeds, and growing dependence upon
                      automobiles  for  commuting  and  commerce
                      increased the need for snow and ice removal for
                      safer roadways (Lord, 1988). Salt was first used on
                      roads in the United States for snow and ice control
                      in the 193Os (Salt Institute, 1994). In the 1960s, the
                      use of salt as a deicing chemical became widespread
                      in  the United  States because salt was readily
                      available, effective on ice and snow, and the lowest
                      cost alternative (Salt Institute,  1994).

                      A common perception that "more is better" led to
                      practices of high application rates of salt. By the
                      late 1950s, however, damage  to roadside sugar
                      maples (a salt- intolerant species) in New England
                      had given rise to concern about the widespread use
                      of salt.   Shortly  thereafter,  contamination to
                      drinking water from wells located near unprotected
                      salt storage areas heightened this concern (Lord,
                      1988).  Other adverse effects from  the runoff of
                      road salts, including the pitting and "rust out" of
                      automobiles and corrosion of highway structures,
                      especially bridge decks (Lord, 1988) were also
                      becoming apparent.

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These  environmental  concerns have  spawned  a
number of research programs.  The goal  of this
research has been to minimize the environmental
effects  of  deicing  while  still  providing  a cost
effective means of clearing roadways for safe travel.
Early in the 1960s,  research began on alternative
deicing chemicals, reduced chemical use, improved
operational practices, pavement heating, pavement
modification, and mechanical approaches (Lord,
1988).  More recently, a "Snow and Ice Control"
study was conducted by the SHRP, a unit of the
National Research Council that was authorized by
Section 128  of the Surface Transportation and
Uniform Relocation Assistance Act of 1987 (SHRP,
1994b). The snow and ice control research included
five   major  initiatives:  improved  operational
procedures;  road weather information  systems;
alternative  deicing  chemicals; pretreatment; and
mechanical approaches. These are discussed further
in the Implementation section below.

ADVANTAGES AND DISADVANTAGES

Highway ice and snow removal is essential both to
public safety and to  local and interstate commerce.
However, the traditional method of deicing roads
through the use of salt has several drawbacks. First,
the use of salt has led to degraded habitats in areas
where salt accumulates in runoff.   Second, the
storage and use of salt can be expensive. In a 1988
paper, Lord estimates  that 400,000 tons  of salt,
approximately 5 percent of the 8 million tons used
annually in the United States is lost from uncovered
stockpiles.   An  estimate of $30  per ton  of salt
equates to a monetary loss of $12  million dollars
each winter (Lord,  1988).   A well planned and
operated snow and ice removal program is essential
to  ensure  public   safety   and  to  minimize
environmental effects and costs.

IMPLEMENTATION

Many initiatives have been taken to control  ice and
snow on roadways while minimizing any associated
environmental effects.  Several of these initiatives
are discussed below
Improved Operational Practices

Clearing roadways after winter storms accounts for
a large portion of the highway maintenance budget
for many northern states.  According to the Salt
Institute's  1991  Snowfighter's  Handbook, snow
removal in 33 snow belt states accounted for 16.2
percent of total highway maintenance costs and 3.6
percent of all highway expenditures (Salt Institute,
1991).

To aid highway management personnel in improving
operational practices, the Salt Institute initiated a
"sensible salting" program in 1967  (Lord, 1988).
These guidelines have evolved with  technology to
include the following: planning; personnel training;
equipment maintenance; spreader calibration; proper
storage;  proper  maintenance  around  chemical
storage areas; and environmental awareness (Salt
Institute,  1994).    Further  information on  the
"sensible salting" program can be obtained from the
Salt Institute, located in Alexandria, Virginia.

While all of these guidelines reflect  key concerns,
proper storage is considered one  of the most
effective in  source  control of deicing chemicals
(U.S. EPA,  1974a).   Guidelines for siting and
designing  deicing chemical  storage facilities  are
provided in  the Manual  for  Deicing Chemicals:
Storage and Handling (U. S. EPA, 1974b).

In addition to reducing the amount of salt lost due
to runoff, the  actual amount of salt used  on the
roads can be reduced. The Regional Groundwater
Center (1995), estimated that 10 million tons of salt
are used each winter in the United States to melt
snow and ice on roads and surface streets (Regional
Groundwater Center, 1995; Salt Institute,  1994).
Salt application rates range from 300 to 800 pounds
per two-lane mile, depending on road, storm, and
temperature conditions (Salt Institute, 1994).

One of the most effective measures for reducing
chemical application has been the use  of a calibrated
spreader using  the   optimal  application rate.
Automatic controls on spreaders are recommended
to ensure a consistent and correct application rate.
The spreader should be  calibrated  prior  to and
periodically during the  snow season, regardless of
whether automatic or  manual controls are used.

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Uncalibrated  controls and poor maintenance  are
often responsible  for excessive  salt  use  (Salt
Institute, 1994).  Guidelines for the calibration of
spreaders and determination of application rates are
given in the Salt Institute's Snowfighter's Handbook
(1991) and in the EPA document Manual for
Deicing Chemicals: Application Practices (U. S.
EPA, 1974a).

Road Weather Information Systems

In an effort to maximize the effectiveness of control
efforts  and  to  reduce  costs, the  SHRP  has
sponsored research using road weather information
systems (RWIS) for highway snow and ice control.
Components of the RWIS include meteorological
sensors, pavement sensors,  site-specific forecasts,
temperature  profiles  of  roadways,  a weather
advisor, communications, and  planning  (SHRP,
1993b, 1993c).

The RWIS can maximize the effectiveness of icing
and plowing efforts by pinpointing and prioritizing
roadways that need attention. It can also eliminate
unnecessary call-outs  and improve scheduling of
crews based on estimates of the extent and severity
of the storm. Research indicates that the use of the
RWIS  technologies can  improve efficiency and
effectiveness  as  well as reducing the  costs of
highway winter maintenance (SHRP, 1993b). Thus,
RWIS may improve snow and ice removal service.
This report concludes that road weather information
system technology may improve service. The report
recommends  that  every   agency that  regularly
engages in snow and ice control consider acquiring
some form of road weather information systems; at
a minimum, forecast services should be used.

The  SHRP has also pointed out that  additional
research beyond the  scope of the original RWIS
project  would  be   helpful  (SHRP,   1993b).
Additional information about RWIS and  intelligent
and localized weather prediction is provided in the
following   SHRP  manuals:     Road   Weather
Information Systems, Volumes 1 and 2  (SHRP,
1993b,  1993c);  and  Intelligent  and  Localized
Weather Prediction (SHRP, 1993a).
Alternative Deicing Chemicals

The  most commonly  used salts for deicing  are
sodium chloride (NaCl) and calcium chloride (CaCl)
(Salt Institute, 1994). The eastern and north-central
sectors of the country use more than 90 percent of
the approximately  10  tons of salt used each year
(Lord, 1988).    However,  sodium  chloride has
several   drawbacks,   including  its   harmful
environmental  effects.  Therefore,  due to both
environmental concerns and the importance of snow
and ice removal programs in terms of public safety
and economic factors, there has been an abundance
of research on alternative deicing chemicals.

An acceptable alternative deicer must  have an
effective melting  range similar to salt's, and must be
cost-comparable  or less  expensive.   One such
chemical  is calcium magnesium acetate (CMA).
CMA is made from delometric limestone treated
with acetic acid. While CMA does not overcome all
the undesirable characteristics of salt, it is still an
effective deicer. CMA is frequently used because it
has less potential to affect  the environment and is
not as corrosive  as salt.  However, to achieve the
same deicing effectiveness  as salt,  CMA materials
need to be applied in larger quantities. In addition,
CMA's cost exceeds salt's  by  a factor of 10 to 20
(Lord, 1988). Continual efforts are being made to
find  a more effective production technology to
lower the cost of CMA, but these efforts have had
limited success (Lord,  1988).

Because  of  the  growing  interest  in  deicing
technology, the  SHRP published a handbook to
standardize testing procedures  used  to  evaluate
deicing chemicals (SHRP, 1992). Deicing chemicals
are evaluated based on their fundamental properties
(e.g., ice melting potential, thermodynamic factors),
physicochemical  characteristics,   deicing
performance (e.g., ice  melting, ice penetration, ice
undercutting),   materials  compatibility,   and
additional engineering parameters.    Additional
information on these testing procedures is provided
in the Handbook of Test Methods for Evaluating
Chemical Deicers(SHKP,  1992).

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Pretreatment

Limited experience  (mainly in Scandinavian and
other European countries) has shown that applying
a chemical freezing-point depressant on a highway
pavement prior to, or very shortly after, the start of
accumulation of frozen precipitation minimizes the
formation of an ice-pavement bond (SHRP, 1994a).
A liquid salt  solution has been applied  prior to a
snowfall in Scandinavia and has proven successful
for pretreatment (SHRP,  1994a).  This anti-icing or
pretreatment practice reduces the task of clearing
the highways and decreases the amount of chemical
applied from that required when deicing  chemicals
are  applied after snow  and ice  have  begun to
accumulate.

When properly implemented, pretreatment practices
may reduce  costs and  be more  effective than
conventional  practices.    However,  most  state
highway agencies have not adopted pretreatment
because  they  are uncertain how  and  when to
implement it.  Other concerns with pretreatment
practices include the imprecision with which icing
events can be predicted,  the uncertainty about the
condition of the pavement surface, and the public's
perception  of wasted  chemicals.   Some  early
attempts to utilize pretreatment practices in  the
United States have failed because of these problems
(SHRP, 1994a).

Technological improvements in forecasting weather
and in  assessing pavement surface  conditions, as
previously  mentioned,  offer the  potential  for
successful   implementation  of   pretreatment.
Research  during the  winters of  1991-92  and
1992-93 by the SHRP indicated that a 40 percent
and 62 percent reduction, respectively, in chemical
usage was possible using pretreatment (SHRP,
1994a).  Pretreatment's success depends on accurate
RWIS,  a  technology  that  is  still   evolving.
Development of spreaders specifically designed or
retrofitted to distribute prewetted solid material or
liquid chemicals, calibration  and  evaluation of
spreaders, training of maintenance personnel, and
effective communication  also need further attention
to ensure the success  of a pretreatment program
(SHRP,  1994a).    Additional  information  on
pretreament is available in the SHRP manual entitled
Development of Anti-Icing  Technology (SHRP,
1994a).

Mechanical and Structural Approaches

Many mechanical and design approaches have been
and are being evaluated  in an effort to improve
snow and ice control practices.   Some of these
attempts have been very  successful, while others
have  had  limited  success  or  need additional
research. This section examines several mechanical
and design approaches, including pavement heating,
pavement  coatings,  mobile  thermal   deicing
equipment, snow fences, and  snowplows. This list
is not comprehensive.

Because of cost or feasibility, pavement heating and
pavement coatings have had limited success in snow
and ice removal.  Pavement heating systems are
costly to install, and operational costs exceed those
of salt on the order of 15 to 30 times (Lord, 1988).
Pavement coatings involve using hydrophobic or
icephobic coatings to reduce the adhesion of ice and
snow to the roadway.   Pavement coatings are
required to weaken  or prevent bonding, while not
decreasing vehicle traction in no-snow conditions.
They are also required to persist in extremely harsh
conditions.  Pavement coatings were  generally
unsuccessful because  they were  unable to meet
these goals (Lord, 1988 andU. S. EPA, 1976b). A
1976 EPA Manual, Development of a Hydrophobic
Substance to Mitigate Pavement Ice Adhesion (U.
S. EPA, 1976b), describes this research. Mobile
thermal deicing equipment has also been evaluated
and determined to be impractical.

Snow fences are used to keep snow from being
blown into drifts. Studies show that snow fences
minimize  costs associated  with  snow  clearing,
reduce  the  formation of compacted snow,  and
reduce the need for chemicals. Mechanical snow
removal costs approximately 100 times more  than
trapping snow with fences (SHRP, 1991).

One concern regarding snow fences focuses on their
position and design. About  20 years ago, it was
very common to find that 4 foot picket snow fences
had buckled under the weight of accumulated snow
(SHRP,  1991).   When  properly  designed  and
positioned, a taller snow fence is more effective than

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the traditional low picket snow fence. Not only is
size relevant to the fence's performance, but so is its
weight.  A lightweight plastic, for example, allows
for the construction of a portable fence up to 8 feet
tall (SHRP, 1991). A 15-foot-tall snow fence used
in Wyoming is  shown in Figure  1.  To minimize
improper positioning and design of snow fences, the
SHRP has  provided publications such as Design
Guidelines for the Control of Blow ing and Drifting
Snow (SHRP, 1994b), Snow Fence Guide (SHRP,
1991), and a 21-minute video entitled "Effective
Snow Fences."

Snowplow  designs  in the  United  States  have
evolved empirically.  These designs, however, have
neglected to incorporate the effects of  the physical
properties of the materials handled by the plow and
the   aerodynamic and hydrodynamic principles
involved  in   the   flow   of  fluidizing  snow.
Consequently,  more  energy  is  expended   in
displacing snow than is necessary, and the short cast
distance necessitates rehandling of the snow (Lord,
1988).  The  SHRP has funded  research at two
universities to improve development of plow blade
design and  cutting  edges  for the  plow blades
(SHRP,  1991).   The first  research  project,
conducted  by  the  University  of  Wyoming
Department of Mechanical Engineering, focused on
developing an  improved  snowplow  blade  that
minimizes energy needed to throw snow clear of the
roadway.   The plow design, based on analytical
methods and laboratory scale experiments, showed
a  20-percent  improvement in  efficiency over
conventional plows.  The plow underwent testing in
West Yellowstone, Montana during the winter of
1990-1991  (SHRP, 1991).  Research for additional
technological advances in plow design is ongoing.

Another  research  project,  conducted  by  the
University of Iowa Institute of Hydraulic Research,
sought  to  improve  snowplow  efficiency  by
improving  cutting edges of plow blades (SHRP,
1993e). Laboratory tests were performed  with a
hydraulic ice-cutting ram to determine the effects of
the geometry of the cutting edge of a  snow plow
blade on the force required to remove ice from a
highway pavement surface. Results of this research
indicate that changes in the cutting edge geometry
result in  substantial improvements in ice cutting;
cutting edge performance  may  still  benefit from
further  studies   (SHRP,  1993e).    An   Iowa


 Source: Reprinted with permission, Tabler and Associates, 1972.

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Department  of Transportation  "plowing truck"
cutting ice is shown in Figure 2.  Additional
information can be obtained in the SHRP manual
entitled "Improved Cutting Edges for Ice Removal"
(SHRP,  1993e).

COSTS

The United States and Canada spend over $2 billion
dollars each year on snow and ice control (SHRP,
1993b).   However, very little cost data has been
generated to show the direct costs of, or the cost
reductions due to,  the specific  snow  removal
alternatives and process improvements discussed in
this fact  sheet.  Some cost information has been
generated for alternative deicing chemicals. NaCl is
both the most common and the most cost-effective
deicing agent, with costs per ton ranging from $17
to $30   (Lord  1988;  Jesperson,  1995).   The
Michigan Department of Transportation drew this
conclusion in a recent evaluation. The evaluation
examined the  costs of sodium chloride (road salt),
CMA, CMS-B  (also known as  Motech), CG-90
Surface Saver (a patented corrosion-inhibiting salt),
Verglimit  (patented concrete  surface  containing
calcium chloride pellets), and  calcium chloride
(MOOT, 1993).  Most of the alternative  deicers
ranged in cost from $200 to $700 a ton (Jesperson,
1995), and were thus significantly more expensive
than sodium chloride.

REFERENCES

1.      Jesperson, K.,  1995.   "Road  Salt  and
       Groundwater, Is It a Healthy Combination?"
       On Tap, Volume 4, Issue 2.

2.      Lord,  B.N.,  1988.  Program  to Reduce
       Deicing Chemical Usage, Design of Urban
       Runoff Quality Controls.

3.      Michigan Department  of Transportation
       (MOOT).   1993.  The Use of Selected
       Deicing Materials on  Michigan Roads:
       Environmental and Economic Impacts.
       Lansing, MI.
  Source: Iowa Institute of Hydraulic Research, 1993.
                           FIGURE 2 A PLOWING TRUCK CUTTING ICE

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4.     Regional Groundwater Center, University of    15.
      Michigan, 1995.  Water Fact listed in On
      Tap, Spring 1995, Volume 4, Issue 2.

5.     Salt Institute, 1991.  "The SnowFighter's    16.
      Handbook. Alexandria, Virginia, 1991.

6.     Salt Institute,  1994. Deicing Salt Facts: A
      Quick Reference. Alexandria Virginia.
                                               17.
                                               18.
                                               19.
                                               20.
7.      Strategic  Highway  Research  Program
       (SHRP), 1991. Snow Fence Guide.  SHRP
       - National Research Council, Washington,
       D.C., SHRP-W/FR-91-106.

8.      SHRP,  1992. Handbook of Test Methods
      for Evaluating Chemicals Deicers.  SHRP
       - National Research Council, Washington,
       D.C., SHRP-H-332.

9.      SHRP,  1993a.  Intelligent and Localized
       Weather Prediction.  SHRP  - National
       Research  Council,  Washington,   D.C.,
       SHRP-H-333.

10.     SHRP, 1993b. Road Weather Information
       Systems, Volume  1:  Research Report.
       SHRP  -  National  Research  Council,
       Washington, D.C., SHRP-H-350.

11.     SHRP, 1993c. Road Weather Information
       Systems, Volume 2:  Implementation Guide.
       SHRP  -National   Research   Council,
       Washington, D.C., SHRP-H-351.
12.     SHRP,  1993d.  SHRP Innovations - Snow    22.
       and Ice Control. H-200 Series Contracts,
       No.20.   Video - 12:41  minutes, SHRP-
       National Research Council, Washington,
       D.C.
                                               21.
SHRP, 1994b.  Development of Anti-Icing
Technology.   SHRP - National Research
Council, Washington, D.C., SHRP-H-385.

Tabler, R., 1972. Evaluation of the First
Year Performance of the Interstate 80 Snow
Fence  System.  Prepared for   Wyoming
Department of Transportation.

U. S. EPA, 1971.  Environmental Impact of
Highway Deicing.  Water Quality Office,
Edison, New Jersey, 11040 GKK 06/71.

U.  S.  EPA,  1972.   A Search:   New
Technology for Pavement Snow and Ice
Control.     Office  of  Research  and
Development,  Washington,   D.C.,
EPA-R2-72-125.

U. S. EPA,  1974a.  Manual for Deicing
Chemicals:  Application Practices.  Office
of Research and Development,  Cincinnati,
Ohio, EPA-670/2-74-045.

U. S. EPA,  1974b.  Manual for Deicing
Chemicals:  Storage and Handling.  Office
of Research and Development,  Cincinnati,
Ohio, EPA-670/2-74-033.

U. S. EPA, 1976a.  An Economic Analysis
of the Environmental Impact of Highway
Deicing.     Office  of  Research  and
Technology,   Cincinnati,   Ohio,
EPA-600/2-76-105.

U.  S.  EPA, 1976b.   Development  of
Hydrophobic  Substance  to  Mitigate
Pavement Ice Adhesion.  Office of Research
and  Development,  Cincinnati,   Ohio,
EPA-600/2-76-242.
13.     SHRP, 1993e. Improved Cutting Edges for
       Ice Removal.  SHRP - National Research
       Council, Washington, D.C., SHRP-H-346.

14.     SHRP,  1994a.  Design Guidelines for the
       Control of Blowing  and Drifting Snow.
       SHRP  -   National  Research  Council,
       Washington, D.C., SHRP-H-381.
                                               23.    U.S. EPA, 1978. Optimization and Testing
                                                     of Highway  Materials  to  Mitigate Ice
                                                     Adhesion  (Interim Report).    Office of
                                                     Research  and  Development,  Cincinnati,
                                                     Ohio, EPA-600/2-78-035.

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ADDITIONAL INFORMATION

Center for Watershed Protection
Tom Schueler
8391 Main Street
Ellicott City, MD21043

City of Hartford, Connecticut
Denise Horan
Metropolitan District Commission, Engineering and
Planning Department
555 Main Street, P.O. Box 800
Hartford, CT 06142-0800

Massachusetts Highway Department
Clem Fung
Research and Materials Group
400 D Street
Boston, MA 02210

State of Minnesota
Lou Flynn
Minnesota Pollution Control Agency
520 Lafayette Road North
St. Paul, MN 55155

Southeastern   Wisconsin  Regional  Planning
Commission
Bob Biebel
916 N. East Avenue, P.O. Box 1607
Waukesha, WI53187

The mention of trade names or commercial products
does not constitute endorsement or recommendation
for the use by the U.S. Environmental Protection
Agency.
                                                                 For more information contact:

                                                                 Municipal Technology Branch
                                                                 U.S. EPA
                                                                 Mail Code 4204
                                                                 401 M St., S.W.
                                                                 Washington, D.C., 20460
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                                                                  Excdence Ih compliance through optltaal technfcal sokrtfons
                                                                  MUNICIPAL TECHNOLOGY BRANCH^

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