United States
Environmental Protection
Agency
Municipal Environmental
Research Laboratory
Cincinnati OH 45268
Research and Development
EPA-600/S2-84-084 June 1984
Project Summary
Capture-and-Containment
Systems for Hazardous Material
Spills on Land
Men/in D. Marshall
Methods were investigated for seal-
ing the surface of soils and thereby
preventing the intrusion of spilled
hazardous materials into the underlying
ground water. Such techniques were
sought to provide immediate, short-
duration protection of spill sites (such
as transportation accidents) until more
permanent cleanup could be initiated.
The goal was to develop a portable, self-
contained, universal sealing system
that could be operated by one person,
retain the spilled materials for 24 hr,
and create no hazards for the user orthe
environment.
The initial plan was to study sprayable
sealants, but laboratory and pilot
testing soon showed this approach to
be impractical since leak-free coatings
could not be achieved. Three classes of
sealants were evaluated, including non-
reactive, reactive, and repellent or
surface-modifying coatings. Several
different commercially available film-
forming materials in each category
were tested, but none of the resulting
films were free of defects. Even poly-
urethane foams, which were the most
encouraging, required a thicker coating
than was practical. The effectiveness of
all spray sealant systems also depended
heavily on weather and soil conditions.
Tests with polyethylene waxes and
films suggested that the latter would be
a useful barrier for a wide spectrum of
hazardous waste spills. Thus evolved
the use of polyethylene tubes, which
appeared to meet the project's require-
ments of capacity, portability, ease of
deployment, and safe operation. Based
on several iterations, a preliminary
design was generated that consisted of
a double-walled polyethylene bag or
one-end-closed tube about 6 ft (1.8 m)
in diameter and 20 ft (6 m) long. An
apron at the open end can be positioned
beneath the leak, and a smaller tube
attached at the opposite end allows
liquid to be drained or transferred to
secondary containment. The package is
less than 2 ft3 (0.05 m3) in volume and
weighs less than 16 Ib (7.5 kg). Such
systems could easily be carried by bulk
transporters and deployed by a single
operator.
This Project Summary was developed
by EPA's Municipal Environmental
Research Laboratory, Cincinnati, OH,
to announce key findings of the research
project that is fully documented in a
separates report of the same title (see
Project Report ordering information at
back).
Introduction
The incidence of accidental land spills
of chemicals has increased with the
growing use and transport of chemicals.
Concern over such spills and the possible
contamination of the soil and ultimately
of ground water has been accompanied by
only limited development of methods
for preventing such contamination, par-
ticularly during the critical hours immedi-
ately after an incident. This project was
undertaken to develop methods that
would seal the surface of soils at a spill
site and prevent the seepage of hazardous
wastes into the groundwater. Application
of such soil sealants immediately after a
spill would confine the spilled material to
the minimum area until more permanent
containment and cleanup procedures
could be implemented.
The design criteria outlined for such an
emergency containment system are quite
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severe. Since site preparation would be
minimal, the sealant must be suitable for
different soils and terrains and must have
resistance to punctures by rocks, twigs,
and other debris. Since accidents fre-
quently occur during inclement weather,
any universal system must also be
unaffected by rain, snow, cold, frozen
ground, etc. Even under such conditions,
the system should be capable of reducing
soil penetration by 95% over a 1 200-ft
(100 m2) area under a 1 -ft (30 cm) head of
liquid for a 24-hr period (based on a
hypothetical 10,000-gal (37900-L) spill)).
Spilled material should not be able to
seep around or under the edge of the
sealed area. Such a system should not
create any permanent environmental
damage or be a danger to the operator.
For prompt implementation, the system
should be portable and self-contained so
that it can either be carried by the
transport vehicle or be brought to the site
by the first emergency response unit. The
system also should be deployable by one
person, even under adverse weather
conditions. Once the emergency is over, it
should be possible to remove or deactivate
the system. And last (if possible), the
system should be fabricated from com-
mercially available components.
The planned program called for using
these criteria to evaluate various in-situ
film-forming systems rather than manu-
factured films. Laboratory tests soon
demonstrated that no candidate sealant
would be able to assure an effective seal
under the expected adverse field condi-
tions and also meet the other criteria.
Consequently, efforts were shifted to
other methods based on the use of
manufactured film barriers. Polyethylene
was selected as the most economical,
widely compatible, and widely available
film for field purchase and installation as
a pond liner.
From this barrier-film approach evolved
the concept of a capture-and-contain-
ment-bag in which a spill, such as that
from a leaking tankcar, could be collected
and held until a temporary holding pond
was prepared. The obvious extension of
this idea was to use the bags instead of a
holding pond if strength and capacity
criteria could be met. The scope of the
project was then redirected to evaluate
various bag designs and constructions
with this goal in mind.
Evaluation Program and
Results
Spray Films
This program initially sought to evaluate
film-forming sealant systems that could
2
be field-applied at a spill to prevent
leaking of materials into the soil in the
vicinity of the spill. When pilot-scale
testing made it clear that leak-free films
were unlikely to be obtained under field
conditions, this phase of the program was
terminated. The following is an abbreviated
description of the experimental work that
led to that conclusion.
Candidate film-forming materials had
been selected using criteria as follows:
able to form a continuous film;
sprayable by a portable system;
able to form a protective skin in a
relatively short time; and
pose no serious threat to operator or
environment.
Initial testing consisted of applying
each material to a cardboard backing and
observing the time for film formation and
the nature of the film. Resistance to
chemicals under a pressure head of 1 ft
(30.5 cm) was then screened using the
film-on-cardboard as the sample. Water,
sulfuric acid, sodium hydroxide, trichloro-
ethylene, methanol, naphtha, and methyl
ethyl ketone were the screening chemi-
cals used. This techniquequickly reduced
the number of promising candidates to
the following five:
'Mention of trade names or commercial products
does not constitute endorsement or recommenda-
tion for use
Polyco 2607,* an adhesive from the
Borden Chemical Co.
Resin 115, a urethane from the Gallery
Chemical Co.
EP 65-86/88, a urethane from the
Ashland Chemical Co.
Zonyl RP, a surfactant from the duPont
Chemical Co.
Clindrol 100CG, a superamide from
the Clintwood Chemical Co.
These candidate systems were subjec-
ted to more extensive laboratory evalua-
tion in a specially designed spray
chamber, which is described in the
original report. Compatibility with and
resistance to a wide range of organic and
inorganic chemicals likely to be encoun-
tered in spill situations were then
determined by exposing a 6-in. (15.2-cm)
disk of the coated and cured asbestos
paper to a liquid head of about 1 ft (30.5
cm) of the challenge chemical and
observing the loss of head with time. This
apparatus also is described in the original
report. Selected results for the promising
candidates appear in Table 1.
Some evaluations were also carried out
after low temperature cures, as might be
experienced in an actual spill situation.
Though cure times were necessarily
longer, the chemical resistances measured
by the liquid transmissions were not
significantly different. Results of these
tests are included in Table 1.
Table 1. Compatibility and Permeation Test Results on Asbestos
Film Material
Challenge Liquid
Liquid Transmission
(ml/24 hr)
at at
20°-22°C* 3°-5°C*
Borden' s 2607
Clintwood's Clindrol
roocc
duPont's Zonyl RP
Gallery's Resin 115
Ashland's EP 65-86/88
Gasoline
Cresol
Naphtha
Water
Sodium hydroxide
Sulfuric acid
Naphtha
Trichloroethylene
Gasoline
Cresol
Naphtha
Water
Trichloroethylene
Gasoline
Cresol
Trichloroethylene
Sodium hydroxide
Sulfuric acid
Gasoline
Cresol
Trichloroethylene
Naphtha
Water
Sodium hydroxide
Sulfuric acid
13.4
1.3
3.9
3.4
2.1
2880-576Cr\
5760-7 200^
5-7
13
9-225
19-380
8-140
0
11.3
2.4
12.7
4.2
7.7
2.8
2.0
3.5
6.9
377
153
15.5
1.8
6.0
56.8
66.2
37.1
5.5
2.3
4.8
3.6
14.5
30.3
2.5
100
1
"Cure temperatures
^Breakthrough occurred within a few minutes.
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Three types of commercially available
equipment were considered for further
testing of these systems: (1) hand-pump
pressurized; (2) propellant pressurized;
and (3) auxilliary-powered, pump pres-
surized. Laboratory tests indicated that
80 to 160 Ib (35 to 70 kg) of material
would be required to seal a containment
area of 1200 ft2 (100 m2). To accomplish
this in a reasonable time (15 to 30 min)
would require spray equipment capable
of dispensing 2.7 to 10.7 Ib/min (1 to 5
kg/min) of chemical. Hand-pumped
systems, while small enough to meet the
project's criteria, would not be expected
to give consistent pressures. Portable
propellant pressurized systems, such as
those used for the application of urethane
foams (e.g. MSA's Rigi-Pak 180) came
closest to meeting the criteria of light
weight and adequate capacity. An auxil-
liary-power system could also be developed
using an external power source estimated
at about 2.75 kW or 2 hp, but there would
be a serious weight penalty (275 to 350
Ib) (125 to 160 kg) and a significant
increase in cost.
Pilot scale tests on 10-ft2 (1-m2) areas
using primarily the Gallery urethane
Resin 115, the MSA Rigi-Pak portable
unit, and a Binks Model 18 spray gun
demonstrated that operator experience
was a major factor in obtaining uniform
coverage at the desired 0.2 Ib/ft2 (0.1
g/cm2) application rate. Surface and
weather conditions, presence of debris,
rocks, water, ice, etc. also appeared to
play a role. Nevertheless, grassy soil (a
relatively ideal substrate) could not be
sealed even at a rate of 1.3 Ib/ft2 (6
kg/m2), apparently because of a "shadow"
effect during spraying. The sealant would
have to be applied from all directions to
obtain complete coverage and adequate
sealing. In view of these considerations,
this phase of the program was discontin-
ued.
Bags
Experiments during the spray sealant
study indicated that polyethylene film
was an acceptable barrier film. From this
conclusion evolved the concept of using a
polyethylene tube to direct bulk transport
leaks and spills of hazardous liquids to
an emergency containment pond. And
because there is a need for temporary
storage of such chemicals until a pond
can be prepared, a larger capacity tube or
bag became the next logical configuration.
This design, incorporating an apron at
one end to capture the leak and a
narrower tube at the opposite end for
controlled discharge or transfer of the
Figure 1. Capture-and-contalnment device in use at a simulated site.
contained liquid (Figure 1), became the
subject of further study.
Such bags could temporarily replace
polyethylene-lined containment ponds
at the site of a spill if they were capable of
retaining spilled material for a reasonable
length of time and in significant volume.
An added advantage would be a reduction
in vapor problems that often accompany a
spill.
The design finally developed was a
polyethylene, pillow-shaped bag about 6
ft (1.8 m) wide and 20 ft (6 m) long, with
an apron at one end and rope lines for use
in positioning the apron capture section
beneath the leak. A polyethylene tube
approximately 4 in. (10 cm) in diameter and
30 ft (9 m) long at the opposite end of the
bag served as an overflow or transfer
tube.
Evaluation of several evolutionary
versions of these bags consisted of
introducing water (simulated spill materi-
al) at 5 gpm (20 L/min) into the apron of a
bag, either fully deployed or rolled-up,
and observing how well the bag unrolled
or retained its shape and position on
sloping ground and how much water
could be contained before the bag failed.
In this manner, it was demonstrated that
the seals or seams of the bag and the
junction with the overflow tube were the
primary sites of failure when subjected to
the internal pressure of liquid. Air
pressure tests on small (6 in. x 9 in. (15.2
cm x 22.8 cm)), 4-mil-thick C\00-/j) bags
suggested that though the film and heat-
sealed seams can be strong enough to
withstand more than 30 in. (75 cm) of
head pressure, quality control in mass
fabrication was not adequate to assure a
reliable seal for this application.
Two prototype bags constructed of
clear (unreinforced), 4-mil-thick (100-/u)
polyethylene tubes 6 ft (2 m) wide and
heat-sealed at one end were found
capable of collecting and holding several
hundred gallons of water (simulated spill
material) and withstanding a maximum
headpressureof24in. (60.9 cm or 0.6m).
Flow into the bag and the development of
the head pressure depended on the slope
of the land on which the bag was
deployed. The one failure occurred at a
fold line in the bag at a head pressure of
about 20 in. (50 cm).
Several full-scale versions were then
constructed of fiber-reinforced polyethy-
lene film to improve tear and puncture
resistance in anticipated field situations.
As these units were filled with water,
leaks developed at or near the point
where the transfer tube was attached,
but not at the double-stitched seams
covered with a polyethylene mastic tape.
When the leaks were repaired and the
bag was retested, some seepage was
observed at the sewn seams, but only
when the bag contained about 900 gal
(3500 L) of water and was under a head of
about 22 in. (55 cm). In a later test, a leak
again developed at the junction of the bag
and transfer tube. This bag, about 20 ft (6
m) long and 8 ft (2.5 m) wide (flat),
weighed only 16 Ib (7 kg) and was readily
deployed in freezing conditions by a
single operator.
Three manufacturers fabricated bags
using both heat-sealed and sewn seams
and fiber-reinforced film. These bags
-------
were tested under field conditions (Table
2).
To reduce the strain on the seams
further, the next design consisted of
double-walled bags, with the outer bag
intended to supply support. Two units
were purchased and tested. The first,
manufactured by the Sheldahl Corp.,
consisted of an innner, 6-mil (150-/u)
polyethylene bag and an outer bag of
fiber-reinforced polyethylene. Though
leakage was minor with this unit, even
when filled to a maximum of 42 in. (105
cm) of liquid head, post-test examination
showed that the inner bag had failed at
some earlier time near the transfer tube
in a manner typical of poorly heat-sealed
seams.
The second double-walled bag, fabri-
cated by Silco Industries, was a quarter-
scale unit. The inner bag was 4-mil (100-
fj) polyethylene with a continuous, heat-
sealed seam. The outer bag was con-
structed of polyethylene mesh with a
double-stitched seam. This double-
walled bag successfully contained a
water pressure head of 46.5 in. (115 cm).
A full-scale version of similar construc-
tion used a fiber-reinforced polyethylene
film outer bag (9-mil (226-u) total
thickness) with a double-stitched seam.
Unfortunately, the outer bag was slightly
larger than the inner bag and did not
provide the expected support. The inner
bag seam failed near the transfer tube
connection after only 150 gal (600 L) of
water had been introduced.
A field demonstration was carried out
at the contractor's facilities using two
prototype bags: a Silco double-walled bag
and a single-ply Katz Co. bag. The
simulated accident was a railroad tanker
laid on its side with leakage around the
top hatch (see Figure 1). Water was the
simulated spill liquid at a leak rate of 5
gpm (20 L/min). The Silco bag had an
inner bag of 6-mil (150-/u) polyethylene
with continuous, heat-sealed seams and
an outer bag of fiber-reinforced polyethy-
ene film with double-sewn seams. The
Katz Co. bag was constructed of a single-
ply (9-mil (225-fj)), fiber-reinforced
polyethylene film with seams heat-
sealed by a proprietary process. The site
had only a gentle slope, which limited
both the potential head buildup and the
total capacity of the bags. The tests did,
however, demonstrate the ease with
which the bags could be deployed and
positioned to capture a spill, even by an
operator in full safety gear, and the use of
the bags in a modular or tandem scheme
to increase capacity. Water (the simulated
spill liquid) was easily transferred from
Table 2. Tests on Fiber-Reinforced Bags
Supplier
Griff olyn Co.
Griff olyn Co.
Griffolyn Co.
Griffolyn Co.
Silco Ind.
Katz Bag Co.
Katz Bag Co.
Fabrication
Heat-sealed
Double-stitched
and silicone taped
Double-stitched and
polyethylene taped
Heat-sealed with
hot air
Heat-sealed
Extrusion process
Mechanical seal
at transfer tube
Pressure
(in.)*
ofHzO
12
12
29.5
5
5
48
12
Observations
Failed near seams
Small leaks at corners
Filled to capacity;
seams seeped
Zipper-like failure
Zipper-like failure
No failure; 1/4 scale;
some seepage
Leakage around seal
* 1 in. = 2.5 cm.
the first, or capturing bag, to a second
downhill bag without the operator having
to re-enter the immediate area of the
spill.
Conclusions
Polyethylene film is a suitable barrier
film for the rapid fabrication of emergency
holding ponds. Polyethylene film (6-mil
(150-/u)) can contain water (simulated
spill material) with more than a foot (30
cm) of liquid head over natural terrain
containing rocks, twigs, and other debris.
This material is readily and widely
available, inexpensive, chemically resis-
tant, and amenable to handling under the
adverse weather conditions (except
strong wind) frequently encountered at
bulk transport spill sites.
Properly fabricated bags or tubes
constructed from 6-mil (150-ya) polyethy-
lene can capture and hold materials
spilled during bulk transport accidents.
These bags are attractive candidates for
onboard spill containment equipment,
since they can be deployed readily by a
single operator immediately after an
incident. The seams of such bags are the
major weak point and the primary source
of leaks. The best strength and resistance
to leakage caused by internal pressure
(liquid head) is obtained with a double-
walled bag consisting of an inner bag
with heat-sealed seams and an outer bag
with sewn seams.
A prototype design includes an apron at
one end of a 20-ft-long (6 m), 6-ft-wide
(2 m) pillow-type bag. Through the
manipulation of ropes, the apron can be
positioned to capture leaking material. A
transfer tube at the opposite end of the
bag (about 4 to 6 in. (10-15 cm) in
diameter and 30 ft (9 m) long) allows for
transfer of the contained liquid to a
second, downhill bag or to a prepared
containment area without the operator
having to re-enter the immediate area of
the spill.
Such bags can contain more than 1000
gal (3785 L) of liquid on a reasonably
sloping terrain, weigh less than 16 Ib (7
kg), occupy a volume of less than 2 ft3
(0.0566 m ), and are readily deployable
by a single person encumbered with full
safety gear and facing adverse weather
conditions. Such bags could probably be
purchased in volume for $50 to $200.
The use of film-forming materials for
onsite sealing of soils is not practical. The
terrain frequently encountered is not
likely to permit achievement of a continu-
ous, leak-free film, even when using
relatively high application rates. Adverse
weather conditions would also contribute
to an expected high frequency of failure for
such sealant films.
More specific conclusions can be
drawn for the three types of film-forming
systems evaluated. Nonreactive sealants
dispensed as solutions or dispersions are
slow to form films under inclement
weather conditions and could create fire or
air-emission problems if used with an
organic solvent. The films produced often
have pinholes. Reactive sealant systems,
though capable of forming films under
adverse weather conditions, exhibit poor
adhesion to the soil and form films with
frequent holes or voids where vegetation
or debris protrudes. Surface modifying
chemicals such as repellents fail to
provide a sealing effect when sprayed on
soil, even under ideal conditions.
Recommendations
The capture-and-containment concept
should be vigorously pursued as a first
response to bulk transport spills. Poly-
ethylene bags are attractive candidates for
an onboard spill containment system for
transport vehicles.
Though polyethylene film has adequate
strength to contain such spills, particular-
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ly when fiber-reinforced, additional work
is needed to fabricate bags with leak-free
seams and junctions (at the transfer tube,
for example).
Before manufacturers will undertake
full-scale development of such units,
evidence is needed of a potential market.
Further design evolution should be
explored with both manufacturers and
spill response personnel.
The full report was submitted in fulfill-
ment of Contract No. 68-03-2507 by
MSA Research Corporation under the
sponsorship of the U.S. Environmental
Protection Agency.
Mervin D. Marshall is with MSA Research Corporation. Evans City, PA 16033.
John E. Brugger is the EPA Project Officer (see below).
The complete report, entitled "Capture-and-Containment Systems for Hazardous
Material Spills on Land," (Order No. PB 84-186 089; Cost: $11.50, 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:
Municipal Environmental Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
-------
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Official Business
Penalty for Private Use $300
CrilC«ii.j 1L
U.S. GOVERNMENT PRINTING OFFICE: 1984-759-102/0979
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