X-/EPA
United States
Environmental Protection
Agency
Municipal Environmental Research
Laboratory
Cincinnati OH 45268
Research and Development
EPA-600/S2-81-207 Oct. 1981
Project Summary
Techniques for Handling
Landborne Spills of Volatile
Hazardous Substances
D. Brown, R. Craig, M. Edwards, N. Henderson, and T. J. Thomas
This study was concerned with the
response needs of teams charged with
handling spills of hazardous volatile
materials on land. Items of hardware
were suggested that could be adapted
or developed to improve spill response
capabilities.
The project examined the available
technology (and the lack thereof)
employed in current spill responses.
The phenomena that accompany spill
volatilization were assessed to deter-
mine and justify physical/chemical
mechanisms that could potentially be
used to control the hazards arising
from volatility. As a result, approxi-
mately 60 items of hardware, which
either exist or could be developed to
improve hazardous volatile spill con-
trol responses, were evaluated.
A set of spill scenarios was devel-
oped to compare the new suggested
technology items with current spill
response procedures.
This Project Summary was devel-
oped by EPA's MunicipalEnvironmen-
tal Research Laboratory. Cincinnati.
OH, to announce key findings of the
research project that is fully docu-
mented in a separate report of the
same title (see Project Report ordering
information at back).
Introduction
Controlling air pollution from ac-
cidental releases of hazardous sub-
stances is an acute problem. The
response time required to prevent air
pollution following a spill can be mea-
sured in minutes or even seconds. This
hazardous situation is further compli-
cated by the dispersed locations at
which accidental spills occur and by the
need for mobilizing an appropriate
control effort in accordance with
geographical and pollution-type de-
mand.
This study was conducted to: (1)
examine the state-of-the-art techniques
presently in use to control or mitigate air
pollution generated by the accidental
release, of hazardous gases or readily
volatile hazardous substances that
represent a potentially serious threat to
human life and the environment and (2)
identify effective, practical, and eco-
nomical technology that can be devel-
oped to eliminate or reduce the incidence
of serious human health problems and
environmental effects resulting from
such air pollution.
The geographic scope included only
spills occurring on land and specifically
excluded accidents where hazardous
materials are spilled in harbors, the
innercontinental shelf, commercial
inland waterways, or other inland water
bodies. Spills covered in this study
included those resulting from railroad,
pipeline, and truck modes of material
transport, as well as accidental releases
during inplant and fixed facility storage.
The hazardous gaseous and volatile
. materials covered in the study included
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only those in the U.S. EPA's "Designation
of Hazardous Substances" list (pub-
lished in the December 30, 1975,
Federal Register) and the U.S. Coast
Guard's "Chemical Hazard Response
Information System (CHRIS)" hazardous
chemical list. A special list, "Hazardous
Chemicals That Produce Vapor," devel-
oped by the U.S. Coast Guard from the
CHRIS 400 list, was extensively used as
a guide for materials included in this
study. The 103 chemicals on this list
produce a significant amount of vapor in
a normal situation; included are chemi-
cals shipped as gases and as liquids that
have relatively high vapor pressures at
ambient temperatures. Radioactive
materials were considered outside the
scope of this study.
A review of state-of-the-art tech-
nology for air pollution control or for
removal of an air pollution source
included currently used, commercially
available, as well as final prototype (or
nearly commercial) technology.
Spill Causes and Current
Responses
Interviews with spill control officials
determined that less than 10% of the
transportation-related spills involve
fires of the spilled material. The
incidents involving fire may reduce the
hazards from the spilled materials but
increase the likelihood of spillage from
adjacent unruptured containers. Be-
cause the control of fire, per se, is
manageable by currently used, com-
monly available technology (water and
foam), and because the control of
vapors, once released, is the subject of
other ongoing research, this study did
not examine vapor control concepts for
spills involving fire.
Spill reports and records were ex-
amined to determine the causes and
relative frequencies of spills of volatile
hazardous materials on land. Reflecting
only reported incidents, the data indicate
that roughly 82% of spills occur during
loading, shipping, and unloading of
materials. A summary of current field
response technologies for controlling
hazardous material vaporization during
such spill incidents was compiled from
staff field experience and from spill
response literature (Table 1). The review
of response technologies indicated that
water flooding is used on approximately
70% of chemical spills, whereas 20%
are treated'with foams and 10% are
treated w^th organic sorbents.
Table 1. Rating of Efficiency of Current Response Techniques to Control Evaporatior
Technique
Reloading to enclosed vessels
Sumping and trenching
Wet foaming
Deep soil burial
Sorbents (straw, mulch, etc.)
Water flooding
Dispersants (on thin water layers)
Air curtain ignition systems
Water shroud lines
High-pressure water fog
Slightly
Effective
X
X
X
X
Moderately
Effective
X
X
Highly
Effective
X
X
X
X
In general, the current state-of-the-
art for control of air pollution from spills
of hazardous materials occurring on
land is simplistic; the response depends
on available local materials (sorbents
such as sand, straw, and flour) and
equipment (such as fire trucks with
water hoses, pumps, and protein-based
foams; bulldozers, etc.). Although a
complete evaluation was not within the
scope of this program, apparently
current response techniques and equip-
ment leave much to be desired in terms
of personal safety. The techniques now
used require close proximity to the spill,
and the personal protective gear provides
inadequate protection for the hazards
encountered.
Local fire departments are most
frequently the first emergency units to
arrive at the spill site. Because of
training, fire department response to
spills often includes water flooding and,
where immediately possible, vapor
source removal. Fire departments
frequently initiate precautionary evacu-
ation .of the population.
Where the local fire department is
more sophisticated and the equipment
is available, foam blankets are some-
times applied to reduce evaporation and
flammability hazards. Final cleanup
activities, however, are generally not
begun until emergency spill* response
teams arrive. Cleanup activities may
then include a variety of separation,
concentration, or disposal procedures.
Combinations may also be practical.
The most effective response pro-
cedures involve vapor source removal
(reloading to enclosed vehicles), deep
soil burial, water flooding, and air
curtain ignition systems (Table 1). Each
of these techniques, however, has
limited applicability. Vapor source
removal implies that the spilled material
can be collected and placed in safe
containers. Water flooding, in essence,
is simple dilution and may cause
undesirable secondary effects. Con-
trolled ignition, although effective, may
not be feasible unless the spill site is
relatively remote. Deep soil burial is
costly, time-consuming, and labor and
land intensive. Therefore, there is
significant room for improving cleanup
technology for spills of hazardous
volatile materials on land.
Hazardous Materials
Volatilization
The phenomena of hazardous mate-
rials volatilization was investigated
during this project. Understanding the
physical properties at work during a spill
and, in particular, knowledge of the
relative importance of the factors
contributing to vaporization were needed
to develop new, improved vaporization
control technologies. Once the material
is spilled, the rate of vaporization and
dispersion depends on a number of
factors including:
• vapor pressure,
• meteorological factors, such as
wind speed, wind direction, atmo-
spheric stability, and (to a lesser
extent) temperature, humidity, and
precipitation,
• atmospheric dilution and diffusion,
• rate of heat transfer to the ground
or atmosphere.
Solar heating of spills was found to be
the predominant source of energy for
vaporization. The effect of rain storms
was not evaluated.
From the CHRIS hazardous chemical
list, 200 materials were selected as
representing substances that may
present a hazard from volatilization
during a spill. Their physical/chemical
properties (boiling point, vapor pressure,
relative vapor density, flash point, water
solubility, and functional groups) weraj
reviewed and tabulated. Relative hazards^
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(in terms of flammability, vapor ir-
ritability, and human toxicity) were
evaluated and control.procedures
(containment, temperature reduction,
and adsorption) were assessed for each
of the 200 chemicals.
Vapor Control Concepts
and Technology
The control approaches investigated
in this study can be categorized into
mechanical, chemical, and physical.
•. Mechanical—By placing a barrier
between the hazardous material
and the environment, the release
of evaporant to the air can be
slowed or stopped. Mechanical
approaches include loading to
closed containers or using diffusion
barriers; the later can slow the net
evaporation rate by hindering or
retarding the passage of molecules
to the vapor phase or by reducing
the spill area available for evapora-
tion. Diffusion barriers include
impermeable covers (such as tar-
paulins), floating objects (such as
"ping-pong" balls), immiscible
liquid layers that can be spread
over the spill, surfactants, and
foams.
• Chemical—By adding selected
chemicals to the spill, the chemical
or physical form of the spill material
can be altered and volatility con-
trolled. Chemical approaches in-
clude adsorption, chemical neu-
tralization, water flushing, and
controlled ignition (adding oxygen).
• Physical—By changing the condi-
tions affecting the spill, vaporization
can be controlled. Physical
approaches include lowering the
spill temperature by adding coolants
(to decrease vapor pressure) and by
using insulation to reduce the rate
of heat transfer to the spilled
chemical (and lower the tempera-
ture of. the spill). The dependence
of vaporization on temperature can
be reduced by increasing the
viscosity and thereby containing
the spill and restricting thermal
transfer by convection. Although
numerous coolants are available to
reduce the temperature of a spill,
only two—dry ice and liquid nitro-
gen (LN2)—were considered. These
coolants were chosen because
they are readily available, provide
low temperature, are nontoxic, and
do not support combustion.
Analysis of these vapor control
techniques indicates that the concept of
reducing the temperature of the spill
will reduce the human hazard associated
with the widest variety of possible spill
materials. This control technique can
immobilize a spill and retard vaporiza-
tion of the spilled material during
removal and disposal. The potential for
dry ice and liquid nitrogen application
was evaluated for the 200 representative
hazardous materials. Nearly all of the
chemicals freeze at liquid nitrogen
temperatures and, in most cases, the
vapor pressure is reduced to insignificant
values. At dry ice temperatures, the
vapor pressure is lowered sufficiently so
that the vapor hazards are significantly
reduced. In addition, in none of the
examples would applying the tempera-
ture reduction concept have worsened
the environmental impact of the spill.
Vapor containment, either with foam,
a polymer layer, or water is also a viable
concept for many materials. Because it
is not universally applicable, however,
and may, in some cases, be counter-
productive, it is considered less useful
than temperature reduction.
Adsorption is also not considered to
be a useful approach. Some materials
are physically adsorbed extremely well,
and adsorption could be an effective
control procedure for these substances.
For the majority of materials, however,
physical adsorption would be a mar-
ginally effective vapor suppression
technique and, therefore, of still less
potential use.
Finally, chemical neutralization is of
quite limited use because only a small
fraction of compounds can be treated in
this manner and would require a
number of different neutralization
agents. In individual cases, neutraliza-
tion might be the treatment of preference,
but generally, this approach is con-
sidered to be of low potential.
A state-of-the-art review was con-
ducted to identify commercially available
or prototype technology that could be
used for applying the promising vapor
control techniques, particularly temper-
ature reduction. These technologies
included:
• diking/earthmoving equipment
• deployment of preformed covers
• large and small object delivery
equipment
• slurry and liquid transfer apparatus
• heat transfer devices
More than 60 techniques were
reviewed for delivery and deployment of
coolants, tarpaulins, plastic sheets, and
foams by plane, helicopter, parachute,
agricultural devices, skiploaders, can-
nons, mortars, catapults, line-guns, and
cranes. No effort was made to select
those delivery and deployment tech-
niques deemed most promising; how-
ever, based on this review, recommen-
dations can be made for further
investigation.
Using cryogenic media to reduce or
eliminate volatile emissions appears to
be most promising, notwithstanding the
potential hazards from the applied
cryogen and from explosive boiling.
Remotely operated systems to deliver
the cryogens are needed, however.
Applying dry ice to reduce spill volatility
has been used sporadically (but with
considerable success) in vapor suppres-
sion. Systems that can project solid-
slurries of granulated dry ice need
considerable attention from researchers.
For example, air-driven seed-blower
guns could be used to deliver sufficient
quantities of granulated dry ice to
blanket a spill in a few minutes.
Further, because of its very low
boiling point, systems using liquid
nitrogen (LN2) could also be used
effectively to suppress vaporization of a
very broad range of hazardous sub-
stances. Transfer hoses could be
designed for the delivery of a solid/liquid
nitrogen slurry. Considerable attention,
however, must be paid to the potential
problems of explosive boiling of LNa and
the possible problem of condensation of
free liquid oxygen.
The full report was submitted in
fulfillment of Contract No. 68-02-1323
by Battelle Columbus Laboratories
under the sponsorship of the U.S.
Environmental Protection Agency.
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D. Brown, R. Craig, M. Edwards, N. Henderson, and T. J. Thomas are with
Battelle Columbus Laboratories, Columbus, OH 43201.
John E. Brugger is the EPA Project Officer (see below).
The complete report, entitled "Techniques for Hand/ing Landborne Spills of
Volatile Hazardous Substances." (Order No. PB 82-105 230; Cost: $11.00.
subject to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Oil and Hazardous Materials Spills Branch
Municipal Environmental Research Laboratory—Cincinnati
U.S. Environmental Protection Agency
Edison, NJ 08837
•tt US. GOVERNMENT PRINTING OFFICE, 1981 — 559-017/7388
United States
Environmental Protection
Agency
Center for Environmental Research
Information
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