United States
Environmental Protection
Agency
Risk Reduction
Engineering Laboratory
Cincinnati, OH 45268
Research and Development
EPA/600/SR-93/172 September 1993
&EPA Project Summary
The Use of Alternative Materials
for Daily Cover at Municipal Solid
Waste Landfills
Frederick G Pohland and Johannes T. Graven
This investigation was conducted to
assess the applicability of currently
available (ca. 1992) alternative materi-
als for use as daily cover at landfills.
Information on characteristics, material
and equipment requirements, methods
of preparation and application, climatic
and operational considerations, effec-
tiveness, and costs were evaluated with
respect to present status and potential
for use.
Results indicated that alternative
daily cover materials (ADCMs) can aug-
ment management practices at munici-
pal solid waste landfills while enhancing
environmental control. Although appli-
cability of ADCMs varied depending on
site specificity and the particular mate-
rial used, most were easily applied, sat-
isfied operational and regulatory
requirements, saved landfill capacity,
decreased soil requirements, and fa-
cilitated leachate and gas management
and control. Although most materials
met established criteria for daily cover,
differences exist that warrant develop-
ment of consensus performance stan-
dards for use and application. Further
development and integration into over-
all landfill management practices are
also justified.
This Project Summary was developed
by EPA's Risk Reduction Engineering
Laboratory, Cincinnati, OH, to announce
key findings of the research project
that is fully documented In a separate
report of the same title (see Project
Report ordering information at back).
Introduction
The diminishing availability of landfill
sites and associated solid waste manage-
ment challenges are major issues nation-
wide. In addition, landfilling costs are
increasing as more stringent regulatory
requirements make design and operation
more complex and attentive to health and
environmental safeguards. This has
prompted recent changes in landfill man-
agement and operational practices to con-
serve space, improve efficiency, and
enhance public acceptance. One such
change is the emphasis being given to
options for meeting daily cover require-
ments. These options include using alter-
native daily cover materials (ADCMs) that
help conserve landfill space and reduce
cover soil requirements without diminish-
ing health, environmental aesthetics, and
other site management and use standards.
Daily cover functions to control disease
vectors, blowing litter, odors, scavenging,
and fires. It should also be effective under
various operating conditions, permit con-
trolled management of leachates and
gases, and improve aesthetics. Because
of its usual availability and traditional use
at landfills, soil remains the most com-
monly employed material for daily cover.
However, soil tends to consume landfill
capacity, is not always readily and eco-
nomically available or suitable under vari-
ous operational conditions, and requires
allocation of equipment and personnel.
Therefore, consideration of commercially
available products and various indigenous
0 Printed on Recycled Paper
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materials as alternatives for daily cover is
warranted.
This investigation addresses the feasi-
bility, benefits, and limitations of currently
available ADCMs from operational, perfor-
mance, environmental, and economic per-
spectives and identifies issues deserving
further consideration and development.
Methods and Procedures
Consistent with project objectives, vari-
ous types of ADCMs were identified and
characterized with respect to use and per-
formance by evaluating the technical lit-
erature, interviewing landfill owners/
operators, and visiting landfills where
ADCMs were being applied. Supplemented
by a questionnaire sent to state regulatory
agencies, U.S. Environmental Protection
Agency's (EPA) regional offices, known
manufacturers and suppliers of ADCMs,
solid waste management associations, and
owners/operators with ADCM experience,
we identified 16 commercially available
and 8 indigenous ADCMs.
Results and Discussion
Types of ADCMs
Commercially Available Products
There has been a significant recent
growth in developing, marketing, and us-
ing commercially available ADCMs at solid
waste landfills. Based on composition,
method of application, and general perfor-
mance, the 16 identified ADCMs were:
four foam, three spray-on, and nine
geosynthetic products; their general char-
acteristics and costs are presented in
Tables 1 through 3. Although it is recog-
nized that individual products will vary with
respect to performance under varying op-
erational conditions (Table 4), key fea-
tures of each of the principal groups are
described below.
Foams
Foam ADCMs are usually applied to
the landfill working face in 2- to 6-in.- (5-
to 15-cm) thick layers by using self-pro-
pelled or towed foam generation and ap-
plication equipment specifically designed
for a particular foam. Both hardening and
nonhardening foams are available, and
they retain their structural integrity from
15 hr to 7 days depending on the specific
product and the effect of climatic condi-
tions (particularly rainfall). Effectiveness
as a daily cover depends on the thickness
of application and sufficiency of coverage,
which may be stipulated by permit re-
quirements. Foam ADCMs are effectively
destroyed placing additional wastes on
them on the next operating day.
Spray-ons
Slurry or emulsion spray-on ADCMs are
applied to the working face using towed
or skid-mounted application equipment,
similar to hydroseeders but specifically
designed for use with a particular product.
These products are applied in a 1/16- to
1/2-in.- (0.16 to 1.27-cm) thick layer and
allowed to dry to a crust or shell. Spray-
ons can retain their matted structure from
1 wk to 3 mo depending on product and
thickness and continuity of coverage.
Working face preparation and operator pro-
ficiency during application are important
factors in determining the effectiveness of
cover. Spray-on ADCMs are also mechani-
cally destroyed by placing additional
wastes on them on the next operating
day.
Geosynthetics
Geosynthetic ADCMs consist of various
types of geosynthetic materials that have
either been developed or adapted for use
as daily landfill cover. Panels fabricated
from these materials are placed over the
working face at the end of the day and
retrieved before the start of the next oper-
ating day. Panel placement and retrieval
is done manually or with available landfill
equipment. At some landfills, specially de-
signed and fabricated ancillary equipment
such as tow bars, lifting bars, reels, or
rollers is used to facilitate panel place-
ment and retrieval. Most panels are re-
used until they no longer provide an
effective cover because of their physical
deterioration resulting from tears and punc-
tures during placement and retrieval from
climatic stresses from wind, rain, and freez-
ing temperatures. Effective life of panels
is 1 to 3 mo, although some panels have
been used for 12 to 18 mo.
Indigenous Materials
Indigenous ADCMs may consist of vari-
ous types of locally available waste prod-
ucts, including ash-based materials,
shredded automobile components and
tires, sludges and sludge-derived prod-
ucts, dredged materials, foundry sand, pe-
troleum-contaminated soils, and shredded
green wastes. Many of these same mate-
rials are routinely disposed of at landfills.
Demonstrating their acceptability may re-
quire physical modification, chemical con-
ditioning, or special analysis, since each
can vary significantly with respect to physi-
cal and chemical characteristics and ef-
fectiveness under various operational and
climatic conditions. Moreover, although in-
digenous materials are usually applied with
available landfill equipment at the same
(or greater) thickness as soil cover, addi-
tional equipment/facilities may be required
for processing and on-stte storage. Indig-
enous materials are generally able to meet
established criteria for daily landfill cover;
however, some materials such as dredged
material, sludges, and sludge-derived prod-
ucts can intensify odors when first ap-
plied, and other materials such as green
wastes and shredded tires are combus-
tible.
Site Operation and
Management Implications for
ADCMs
The merit of using of ADCMs at landfills
is often determined by operational, perfor-
mance, and economic comparisons with
soil. These comparisons may include in-
spection of the effect on landfill capacity,
soil requirements, application and perfor-
mance considerations, climatic conditions,
leachate and gas management, opera-
tional costs, and other site-specific require-
ments.
Effect on Landfill Capacity
Landfill owners/operators identify the
potential savings in landfill capacity as the
most important reason for using ADCMs,
primarily because of extended landfill life
and additional revenues from the space
otherwise occupied by soil. Such savings
are generally independent of the type of
alternative cover material used but directly
depend on how often the ADCM is actu-
ally used in lieu of soil. The latter is largely
determined by climatic conditions, but
availability of materials or constituents, the
condition and/or age of the material, and
the efficiency and reliability of the applica-
tion equipment or methods are also im-
portant.
Effect on Soil Requirements
Use of ADCMs decreases the need and
relative costs for soil as daily cover, so
that on-site soils are conserved or offsrte
acquisition is reduced. Equipment and per-
sonnel costs for moving and placing soil
cover also decreases, as does vehicular
traffic, road maintenance (both offsrte and
onsite), and noise and dust generation.
Application and Performance
Considerations
Ease of application with less equipment,
personnel, and time than that required for
soil cover is an important operational and
economic consideration. This can be par-
ticularly significant for sites where adverse
weather conditions such as rain or freez-
ing temperatures can curtail use of soil
cover to a greater degree than would oc-
cur with certain ADCMs. Moreover, since
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less time may be needed to apply ADCMs,
larger quantities of wastes can be received
at the landfill for longer periods of time
than would otherwise be possible, thereby
extending service and increasing associ-
ated revenues.
Although most ADCMs are able to meet
established criteria for daily cover from
both operational and regulatory perspec-
tives, distinctions exist among the various
ADCMs with regard to their effectiveness
for odor and fire control and for minimiz-
ing moisture infiltration under various cli-
matic and operational conditions. In
addition, site-specific circumstances will
often dictate the approach to satisfy cover
criteria. With few exceptions, performance-
based standards for evaluating the effec-
tiveness of ADCMs have not been
established, and subjective judgement
comparing the ADCM to a standard 6 in.
(15 cm) of compacted soil is often used.
Effect of Climatic Conditions
Various conditions of rainfall, tempera-
ture, and wind affect ADCM use—the ease
and frequency of application and retrieval
and the effectiveness. Moderate to heavy
rains can wash out nonhardening foams,
and hardening foams and spray-ons can-
not be applied under such conditions. Rain
can also increase the weight of nonwoven
geosynthetics and make them more diffi-
cult to handle. Under windy conditions,
panel placement may not only require ad-
ditional time and personnel but may also
be unsafe or impractical. Geosynthetic
panels can also freeze to the working
face or be covered with snow, both of
which increase the risk of loss or damage
on retrieval.
Leachate and Gas Management
The use of ADCMs can enhance con-
trolled leachate and gas management by
limiting the development of intervening
cover layers. Eliminating such layers fa-
cilitates unimpeded movement and collec-
tion of leachates and gases within and
between the landfill cells and when
leachate recycle for accelerated stabiliza-
tion is practiced. Therefore, commercially
available products may be preferred over
some of the indigenous materials.
Although foam and spray-on covers are
mechanically destroyed when additional
wastes are placed over them on subse-
quent operating days, these and some
indigenous materials remain within the
landfill and may affect leachate composi-
tion and its subsequent disposition or oth-
erwise affect the progress of landfill
stabilization. Because stabilization pro-
cesses within a landfill normally occur over
extended periods, and many ADCMs have
been available and used for only a rela-
tively short time, potential long-term ef-
fects of constituents leached from
alternative cover materials, although gen-
erally considered to be minimal, may need
to be established.
Operational Costs and Site
Requirements
Operational costs and other site-spe-
cific requirements may also affect the fea-
sibility of using a particular ADCM.
Although the determination of potential cost
savings associated with ADCMs is usually
made by comparing them with soil as a
daily cover, additional factors such as avail-
ability of storage facilities for some ADCM
constituents and application equipment,
utility requirements, landfill working-face
preparation needs, and operator skills and
safety implications must also be evalu-
ated.
Conclusions
Based on the results of these investiga-
tions, the following conclusions can be
drawn:
Use of alternative materials for
daily cover in lieu of soil can re-
sult in operational, performance,
environ-mental, and economic
benefits at municipal solid waste
landfills. These benefits include
ease of application, improved ef-
fectiveness in meeting site opera-
tional and regulatory requirements,
savings in landfill capacity, de-
creased requirements for soil, and
more effective management of
leachates and gases.
Most alternative daily cover materi-
als are able to meet established
criteria for daily cover under vari-
ous operational and climatic condi-
tions. Certain materials are more
effective than soil as a daily cover,
especially with respect to control of
vector access, blowing litter, and
odor generation and to the minimi-
zation of moisture infiltration.
The effectiveness of ADCMs de-
pends on properly preparing the
landfill working face preparation
and on equipment-operator profi-
ciency. Climatic conditions and
other site-specific considerations
will also influence the choice of
ADCM, its method of application,
and effectiveness as daily cover.
• Evaluation of the effectiveness of
ADCMs in meeting operational and
regulatory criteria for daily cover is
generally based on subjective com-
parisons with soil cover. Lack of
consensus, performance-based
standards for various operational
and climatic conditions limits the
selection and regulation of ADCMs
for landfill applications.
Recommendations
Recommendations regarding the future
development and use of ADCMs include:
integration of ADCMs as alterna-
tive cover options into the design,
construction, and operation of land-
fills for solid waste management;
• establishment of performance-based
standards to permit more objective
evaluations of the short- and long-
term effectiveness and suitability of
ADCMs; and
• coordination between manufacturers
of ADCMs and the regulatory and
user communities to ensure appro-
priate use of ADCMs and to estab-
lish training and certification
programs.
The report was submitted in fulfillment
of Contract No. 68-C1-0018 by Eastern
Research Group, Inc., under the sponsor-
ship of the U.S. Environmental Protection
Agency.
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Table 1. Foam Cover Products
Product/
Manufacturer
RUSMARP
RUSMAR, Inc.
West Chester, PA
Product
Description
Nonhardening foam
(consistency of
shaving cream)
Material
Cost**
$0.06-0.07/tf
($0.65-0.75/rrf)
Application
Equipment Cost*
Self-propelled
(includes BSD)-
$250,000-$300,000
Towed- from $85,000
Comments
BSD Bulk Storage and Dilution Unit for
foam concentrate. Self-propelled and
large-capacity towed equipment
are freeze protected. Average
cover duration: 15-20 hr*
San/Foam™
3M Industrial
Chemical
Products Div.
St. Paul, MN
TerraFoam™
National Foam, Inc.,
Environmental
Products Div.
Exton, PA
Polyamino hardening
foam (resembles
Styrofoam® when cured)
Nonhardening foam
(consistency of mousse)
$0.08-0.10/ff
($0.86-1.08/m2)
$0.05-0.06/f?
($0.54-0.65/1^)
Self-propelled-
$130,000
Towed-
$40,000-$70,000
Self-propelled-
$300,000
Truck-mounted-
$70,000
Average cover duration:
3-6 days*
Average cover duration:
3-7 days*
TopCoaf™
Central Fiber
Corp.
Wellsville, KS
Polymer-based
hardening foam
$0.10-0.12/ff
($1.08-1.29/rr?)
Towed-
$25,000
Cost information is based on limited
field tests. Insufficient information is
available on cover duration.
' 1992 cost information obtained from manufacturer's representative. Personnel costs associated with the application of the foam and application equipment maintenance costs
are not included.
t Material cost is based on application of3-in.-( 7.5-cm) thick layer, except for San/Foam™ which is based on a 2-in.-( 5cm) thick layer.
* Duration of cover depends on climatic conditions, particularly rain.
Table 2. Spray-on Cover Products
Product/
Manufacturer
Product
Description
ConCover®
New Waste
Concepts, Inc.
(formerly
Newastecon, Inc.)
Perryburg, OH
Land-Cover Formula
440
Enviro Group, Inc.
Indianapolis, ID
Bay Hill Marketing, Inc.
Altamonte Springs, FL
Posi-Shell™
Landfill Services Corp.
Apalachin, NY
Aqueous slurry of recycled
newspaper/wood fibers
and binding agent; hardens to
form 1/8- to 1/4-in.-
(0.32- to 0.64-cm) thick cover.
Aqueous clay/polymer-based
emulsion; hardens to form
1/16- to 1/8-in- (0.16- to
0.32-cm) thick cover.
Aqueous slurry of recycled
newspaper/plastic fibers
and cement kiln dust binder;
hardens to form 1/4- to 1/2-in.-
(0.64- to 1.27-cm) thick cover.
Material
Cost1
Application
Equipment Cost*
Comments
$0.07-0.09/ff
($0.75-0.97/nrf)
$0.03-0.06/f?
($0.32-0.65/171*)
$18,000-$40,000
$4,200-$ 12,500
($0.32-0.54/m2)
Equipment is leased
for$4,700/mo.
Small capacity application
equipment is towed; large
capacity units are skid-
mounted. Average cover
duration: 7-30 day si
Application equipment is
skid-mounted. Average
cover duration: 1-3 mo.f
Application equipment is
towed. Storage silo required
for cement kiln dust is also
provided. Average cover
duration: 1-3 mo J
'1992 cost information obtained from manufacturer's representative. Personnel costs associated with spray-on application and
application equipment maintenance costs are not included.
1Duration of cover depends on the thickness and continuity of application.
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Table 3. Geosynthetic Cover Products
Product/ Product
Manufacturer Description
Airspace Saver®
Wire Rope Specialist
Baton Rouge, LA
Aqua-Shed™
Aqua-Shed
Manufacturing Corp.
Florence, SC
CORMIER
Cormier Textile
Products
Sanford, ME
COVERTECH C-440
COVERTECH
Fabrication, Inc.
Rexdale, Ontario
FabriSoiP
Phillips Fibers Corp.
Greenville, SC
GriffolyrP
Reef Industries, Inc.
Houston, TX
Poly felt XO0 10
Polyfelt, Inc.
Evergreen, AL
Sani Cover™
Fluid Systems, Inc.
Cincinnati, OH
Typai®
Exxon Chemical
Company
Old Hickory, TN
* 1992 cost intormatinn nhtaii
Woven, high-density polyethylene,
coated with low-density
polyethylene; 9 oz/yd2
(305 g/m2); reinforced with
nylon strapping (one side)
Polyvinyl chloride coated
on one side with adhesive;
7ozfyd2(237g/m2)
Woven, high-density polyethylene,
coated with low-density
polyethylene; WP-640 -
4.3 oz/yd2 (146 g/m2); WP-1440
-5.2ozfyd2(176g/m2)
Woven, high-density polyethylene,
coated with low-density
polyethylene; 9 oz/yd2 (305 g/m2);
reinforced with nylon strapping
on both sides.
Nonwoven, needle-punched
polypropylene; 6 oz/yd 2
(203 g/m2)
Low-density polyethylene-
coated co-polymer and
nylon yarn laminate;
4.9ozfyd2(166g/m2)
Nonwoven, spun-bonded,
needle-punched polypro-
pylene; 8 oz/yd2 (271 g/m2)
Polypropylene;
6 oz/yd 2 (203 g/m2)
(See comments)
Nonwoven, spun-bonded,
needle-punched polypro-
pylene; 5.8 oz/yd2 (197 g/m2)
Material
Cost*
$0.40/1?
($4.3 1/m2)
$0. 12-0. 14/tf
($1.29-1. 51/rrf)
$0.085-0. 12/ft2
($0.01 5-0. 032/m2)
$0.55/ff
($5.92/m2)
$0. 16-0. 19/ft2
($1.72-2.05^)
$0.1 3-0.1 5/tf
($1.40-1.61^)
$0.22-0.25/ff
($2.36-2.69^)
$0.13-0.15/1?
($1.40-1.61/trf)
$0. 15/tf
($0.6 1/m2)
Effective
Cost*
$0.001 7-0.0020/ff
($0.018-0.022/m2)
$0. 12-0. 14/ff
($1.29-1.51/m2)
$0.001 4-0.0030/ff
($0.91-1. 29/m2)
$0.0023-0.0028/ff
($0.025-0.030/m2)
$0.0053-0.0095/ff
($0.057-0. 102/m2)
$0.0005-0.0008/ff
($0.005-0.009/m2)
$0. 0037-0. 0125/ff
($0.040-0. 135/m2)
$0. 004-0. 008/ff
($0.043-0.086^)
$0.0025-0.0038/ft2
($0.027-0.041/m2)
Comments*
Average duration of panels is
10- 12 mo (200-240 reuses);
some last 18 mo.
Panels are only placed manually
and adhere to the working face.
They are not subsequently
removed or reused. Average
cover duration is 2-3 mo.
Average duration of panels
is 2-3 mo (40-60 reused);
some last 6 mo.
Average duration of panels
is 10- 12 mo (200-240 reuses);
some last 14 mo.
Average duration of panels
is 20-30 days (20-30 reuses).
Average duration of panel is
10-1 2 mo (200-240 reuses).
Average duration of panel is
1-3 mo (20-60 reuses).
San/Cover™ 150 is a nonwoven,
needle-punched material while
SaniCover™ 250 is a woven
material. Average duration of
panel is 20-30 days (20-30 reuses).
Average duration of panel
is 2-3 mo (40-60 reuses).
placement/retrieval of panels are not included, '-™ «^,,w,,u«,dno personnel costs assorted w,th
Effective cost = material cost/number of reuses. (For panels with effective life > 1 mo, 20 uses/mo were assumed)
^f ,!2y f °therwise' geosynthetic panels are placed manually or with available landfill equipment. Specially designed and
fabncated ancillary equipment (e.g., tow bar, lifting bar, reel, or roller) is used at some sites to facilitate panel
placement/retrieval and reduce wear and tear.
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Table 4. Operational Considerations - Commercial Products
Foams Spray-ons
Operational
Feature
Geo-
synthetics
Comments
Access control
(insects, birds and
animals
Fire retardation
- Noncombustible
Yes*
Yes*
Yes
See comments
See comments
No
- Limits air intrusion
- Provides barrier
within landfill
Blowing liner control
Odor and other air
emission control
Dust control
Yes*
No
Yes*
Yes*
Yes
Yes*
No
Yes*
Yes*
Yes
Yes*
No
Yes
Yes*
Yes
Water infiltration
control
See comments
Yes*
Yes*
Leachate and
gas migration
Control
See comments See comments
See comments
Aesthetically pleasing Yes*
appearance
Yes*
Yes*
The sticky consistency of nonhardening foams
and hardening foam and spray-ons discourages
insects and birds from landing and animals from
digging. Hardening foams and spray-on
subsequently form a resilient barrier.
Geosynthetics completely cover wastes,
denying access to insects, birds, and animals.
Nonhardening foams are noncombustible,
and SaniFoam™, a hardening foam, is rated
nonflammable and self-extinguishing.
(Insufficient information is available regarding the
combustibility of TopCoaf™ foam.)
Constituents of spray-ons may be
combustible, but they are applied as an
aqueous slurry/emulsion. Spray-ons are
generally considered nonflammable when
dry/hardened. Some geosynthetics are also
rated nonflammable and self-extinguishing,
while moisture absorbed by nonwoven
materials can reduce their combustibility.
Foams, spray-ons, and geosynthetics
provide a barrier that can reduce/prevent
the transfer of atmospheric oxygen to the
working face.
Foams and spray-ons are destroyed and
geosynthetics are removed before placement
of wastes on subsequent days.
Foams and spray-ons adhere to and contain
wastes, and geosynthetics completely cover the
wastes, preventing blowing litter.
Foams and spray-ons provide a barrier against
odor and other emissions. Geosynthetics trap
odors and emissions while in place; they
may be released when panels are retrieved.
Foams, spray-ons, and geosynthetics adhere to
and/or contain materials prone to dusting. In
addition, since the use of these materials
eliminates the need to transport and place soil
cover, that element of dust generation is also
reduced.
Hardening foams and spray-ons form a cover that
can shed rain-water when hardened whereas
nonhardening foams are generally not as
effective during moderate to heavy rain.
Many geosynthetic materials effectively shed
rainwater, particularly those that are water
repellant. Although nonwoven geotextiles initially
absorb some moisture, they are also able to
subsequently shed rainwater.
Leachate and gas movement are not curtailed,
since foams and spray-ons are destroyed and
geosynthetics are removed on subsequent days.
* Effectiveness depends on complete and continuous application onto the wastes.
f Effectiveness depends on the permeability of the particular material to air and water.
-&U.S. GOVERNMENT PRINTING OFFICE: 1993 • 7SO-O7I/80066
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F.G. Pohland and Johannes T. Graven are with the Department of Civil
Engineering, University of Pittsburgh, Pittsburgh, PA 15261-2294.
Robert E. Landreth is the EPA Project Officer (see below).
The complete report, entitled "The Use of Alternative Materials for Daily Cover
at Municipal Solid Waste Landfills," (Order No. PB93-227197; Cost:
$27.00, 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:
Risk Reduction Engineering 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
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
EPA/600/SR-93/172
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